Patent Publication Number: US-2022236513-A1

Title: Camera module

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. § 119(a) of Korean Patent Application No. 10-2021-0012364 filed on Jan. 28, 2021 in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference for all purposes. 
     BACKGROUND 
     1. Field 
     The following description relates to a camera module. For example, the following description relates to a camera module configured to reduce resolution degradation caused by foreign matter. 
     2. Description of Related Art 
     The resolution and field of view of a camera module may depend on a condition of a forwardmost lens. For example, foreign matter (e.g., dust, frost or water droplets) adhering to the forwardmost lens may reduce the resolution of the camera module or make an angle of view and the field of view actually narrow. In particular, frost, dew or the like may easily adhere to the forwardmost lens of the camera module, which is exposed outwardly, and the camera module may thus have a reduced resolution and a blocked field of view, due to this foreign matter. 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     In one general aspect, a camera module includes: a lens barrel accommodating a lens; a forwardmost lens disposed closer to an object side than the lens; an energy generation device configured to supply energy to the forwardmost lens; and an energy transfer member disposed in contact with the forwardmost lens and the energy generation device, and configured to transfer the supplied energy to the forwardmost lens. 
     The lens barrel may include: a first accommodating portion accommodating the lens, and a second accommodation portion accommodating the energy transfer member. 
     The energy generation device may be disposed in the second accommodation portion. 
     The camera module may further include an insulation member disposed in the second accommodation portion, and configured to block the supplied energy from being transferred to the lens barrel. 
     The energy generation device may be further configured to generate either one or both of thermal energy and vibration energy. 
     The energy generation device may be disposed between the lens barrel and the energy transfer member. 
     The energy transfer member may be made of a material having a thermal conductivity higher than a thermal conductivity of the lens barrel. 
     The energy transfer member may be in contact with a flange portion of the forwardmost lens. 
     The forwardmost lens and the energy transfer member may include respective inclined surfaces coupled to each other such that the forwardmost lens and the energy transfer member are aligned with each other, or the forwardmost lens may include protrusions and the energy transfer member may include grooves, and the protrusions and the grooves may be coupled to each other such that the forwardmost lens and the energy transfer member are aligned with each other. 
     The energy transfer member may be disposed between the forwardmost lens and the lens. 
     The camera module may further include a cover member coupled to the lens barrel, and configured to secure the forwardmost lens to the lens barrel. 
     In another general aspect, a camera module includes: a first lens barrel accommodating a lens; a second lens barrel coupled to the first lens barrel, and coupled to or in contact with a forwardmost lens disposed in front of the lens; an energy generation device disposed in contact with the second lens barrel, and configured to transfer energy to the forwardmost lens through the second lens barrel; and a cover member coupled to the first lens barrel or the second lens barrel, and configured to prevent the forwardmost lens from being separated from the lens barrel. 
     The second lens barrel may be made of a material having a thermal conductivity higher than a thermal conductivity of the first lens barrel. 
     The second lens barrel may be in contact with a flange portion of the forwardmost lens. 
     The second lens barrel may include an extension in contact with an inner circumferential surface of the energy generation device. 
     The first lens barrel may include a space or a hole, and the extension may be inserted into the space or the hole. 
     In another general aspect, a camera module includes: a first lens barrel accommodating one or more lenses; a second lens barrel coupled to the first lens barrel; an additional lens disposed closer to an object side of the camera module than the one or more lenses, and in contact with the second lens barrel; and an energy generation device disposed between the first lens barrel and the second lens barrel, and configured to transfer either one of thermal energy and vibration energy to the additional lens through the second lens barrel. 
     The energy generation device may not in contact with the first lens barrel. 
     The camera module may further include an insulation member disposed between the energy generation device and the first lens barrel. 
     The camera module may further include a buffer member disposed between the energy generation device and the first lens barrel, and configured to press the energy generation device against the second lens barrel. 
     A material of the second lens barrel may have a thermal conductivity higher than a thermal conductivity of a material of the first lens barrel. 
     Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross-sectional view of a camera module, according to an embodiment. 
         FIGS. 2 through 4  are views each illustrating other types of a second lens barrel and an energy generation unit shown in  FIG. 1 . 
         FIGS. 5A through 6B  are cross-sectional views showing other types of a forwardmost lens and the second lens barrel, shown in  FIG. 1 , that are coupled to each other. 
         FIGS. 7 through 8C  are cross-sectional views of a camera module, according to another embodiment. 
         FIG. 9  is a cross-sectional view of a camera module, according to another embodiment. 
         FIG. 10  is a cross-sectional view of a camera module, according to another embodiment. 
         FIGS. 11 and 12  are an exploded perspective view and a combined cross-sectional view of a modified example of the second lens barrel and heat generation device shown in  FIG. 10 . 
         FIGS. 13 through 15  illustrate modified examples of the camera module shown in  FIG. 10 . 
         FIG. 16  is a cross-sectional view of a camera module, according to another embodiment. 
         FIGS. 17 through 19  illustrate other types of a barrel holder and an energy generation unit shown in  FIG. 16 . 
         FIG. 20  shows a modified example of the camera module shown in  FIG. 16 . 
         FIGS. 21A through 22B  are exploded perspective views and combined cross-sectional views of modified examples of the second barrel holder and the energy generation unit shown in  FIG. 16 . 
         FIG. 23  is a cross-sectional view of a camera module, according to another embodiment. 
         FIG. 24  is a cross-sectional view of a modified example of the camera module shown in  FIG. 23 . 
         FIG. 25  is a cross-sectional view of a camera module, according to another embodiment. 
         FIGS. 26A through 27B  are exploded perspective views of other types of a lens barrel and an energy generation unit. 
         FIG. 28  is a cross-sectional view of a camera module, according to another embodiment. 
         FIGS. 29A and 29B  are cross-sectional views each illustrating modified examples of a first lens and a barrel holder that are coupled to each other. 
         FIGS. 30A and 30B  are perspective views of modified examples of an energy generation unit. 
         FIG. 31  is a cross-sectional view of a modified example of the camera module shown in  FIG. 28 . 
         FIGS. 32 through 34  are cross-sectional views of a camera module, according to another embodiment. 
         FIG. 35  is an exploded perspective view of a camera module, according to another embodiment. 
         FIG. 36  is an assembled perspective view of the camera module shown in  FIG. 35 . 
         FIG. 37  is a cross-sectional view of the camera module shown in  FIG. 36 . 
         FIG. 38  is an exploded perspective view of a camera module, according to another embodiment; 
         FIGS. 39A and 39B  are perspective views each illustrating a lens barrel and the heat generation device shown in  FIG. 38 , partially coupled to each other. 
         FIG. 40  is an assembled perspective view of the camera module shown in  FIG. 38 . 
         FIG. 41  is a cross-sectional view of the camera module shown in  FIG. 38 . 
         FIG. 42  is a cross-sectional view of a camera module, according to another embodiment. 
     
    
    
     Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience. 
     DETAILED DESCRIPTION 
     The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be apparent after an understanding of the disclosure of this application. For example, the sequences of operations described herein are merely examples, and are not limited to those set forth herein, but may be changed as will be apparent after an understanding of the disclosure of this application, with the exception of operations necessarily occurring in a certain order. Also, descriptions of features that are known in the art may be omitted for increased clarity and conciseness. 
     The features described herein may be embodied in different forms, and are not to be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many possible ways of implementing the methods, apparatuses, and/or systems described herein that will be apparent after an understanding of the disclosure of this application. 
     Herein, it is to be noted that use of the term “may” with respect to an embodiment or example, e.g., as to what an embodiment or example may include or implement, means that at least one embodiment or example exists in which such a feature is included or implemented while all examples and examples are not limited thereto. 
     Throughout the specification, when an element, such as a layer, region, or substrate, is described as being “on,” “connected to,” or “coupled to” another element, it may be directly “on,” “connected to,” or “coupled to” the other element, or there may be one or more other elements intervening therebetween. In contrast, when an element is described as being “directly on,” “directly connected to,” or “directly coupled to” another element, there can be no other elements intervening therebetween. 
     As used herein, the term “and/or” includes any one and any combination of any two or more of the associated listed items. 
     Although terms such as “first,” “second,” and “third” may be used herein to describe various members, components, regions, layers, or sections, these members, components, regions, layers, or sections are not to be limited by these terms. Rather, these terms are only used to distinguish one member, component, region, layer, or section from another member, component, region, layer, or section. Thus, a first member, component, region, layer, or section referred to in examples described herein may also be referred to as a second member, component, region, layer, or section without departing from the teachings of the examples. 
     Spatially relative terms such as “above,” “upper,” “below,” and “lower” may be used herein for ease of description to describe one element&#39;s relationship to another element as shown in the figures. Such spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, an element described as being “above” or “upper” relative to another element will then be “below” or “lower” relative to the other element. Thus, the term “above” encompasses both the above and below orientations depending on the spatial orientation of the device. The device may also be oriented in other ways (for example, rotated 90 degrees or at other orientations), and the spatially relative terms used herein are to be interpreted accordingly. 
     The terminology used herein is for describing various examples only, and is not to be used to limit the disclosure. The articles “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “includes,” and “has” specify the presence of stated features, numbers, operations, members, elements, and/or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, members, elements, and/or combinations thereof. 
     Due to manufacturing techniques and/or tolerances, variations of the shapes shown in the drawings may occur. Thus, the examples described herein are not limited to the specific shapes shown in the drawings, but include changes in shape that occur during manufacturing. 
     The features of the examples described herein may be combined in various ways as will be apparent after an understanding of the disclosure of this application. Further, although the examples described herein have a variety of configurations, other configurations are possible as will be apparent after an understanding of the disclosure of this application. 
     A camera module according to the disclosure herein may be mounted on a device that is easily exposed to an external environment. For example, the camera module may be mounted on a vehicle or a security monitoring device. However, a scope of use of a camera module according to this disclosure is not limited to the above-described devices. For example, a camera module according to this disclosure may be mounted on a communication device at a common entrance of an apartment complex, a communication device at a building entrance, etc. 
     The camera module may convert an optical signal reflected from a subject into an electrical signal. For example, the camera module may convert an optical signal incident through one or more lenses into an electrical signal through an image sensor. A resolution of the camera module may depend on an amount of light incident on the camera module. For example, the amount of light incident on the camera module may be decreased or increased due to foreign matter adhering to a glass cover panel or a forwardmost lens of the camera module. In this case, an image may not be smoothly converted through the image sensor. 
     A camera module according to the disclosure herein may remove the foreign matter adhering to the glass cover panel or the forwardmost lens of the camera module by using various energy shapes. For example, a camera module according to an embodiment may use thermal energy to remove water droplet, frost, moisture, ice or the like adhering to, condensed on, or aggregated on the glass cover panel or the forwardmost lens thereof. A camera module according to another embodiment may use vibration energy to remove the foreign matter adhering to the glass cover panel or the forwardmost lens thereof. A camera module according to yet another embodiment may use magnetic energy to remove the foreign matter adhering to the glass cover panel or the forwardmost lens thereof. 
     Hereinafter, example embodiments will be described in detail with reference to the accompanying drawings. 
       FIG. 1  illustrates a camera module, according to an embodiment. 
     Referring to  FIG. 1 , a camera module  1001  may include an optical system  100 , a lens barrel  200  and an energy generation unit (or energy generation device)  400 . 
     The optical system  100  may form an image at a predetermined position by using light reflected from a subject. For example, the optical system  100  may have refractive power to form the image at the predetermined position by using light incident thereon. The optical system  100  may include the plurality of lenses. For example, the optical system  100  may include five or more lenses, including a first lens  110 , a second lens  120 , a third lens  130 , a fourth lens  140 , and a fifth lens  150 . However, the number of lenses included in the optical system  100  is not limited to five. For example, the optical system  100  may include four or fewer lenses or include six or more lenses. 
     The first to fifth lenses  110 ,  120 ,  130 ,  140  and  150  may be sequentially arranged from an object side. For example, the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140  and the fifth lens  150  may be arranged sequentially from the object side in an optical axis direction. The first lens  110  to the fifth lens  150  may each be made of a plastic or glass material. For example, the first lens  110  to the fifth lens  150  may be all made of the glass material or all made of the plastic material. However, the first lens  110  to the fifth lens  150  may not all be made of the same material. For example, at least one of the first lens  110  to the fifth lens  150  may be made of the glass material and the remainder of the first lens  110  to the fifth lens  150  may be made of the plastic material. As a specific example, the first lens  110 , which is exposed outward, may be made of the glass material. As another example, a lens of the optical system  100 , having strong refractive power, may be made of the glass material. The former example may reduce lens breakage due to external impact, and the latter example may reduce a change rate of a focal length of the camera module  1001  due to a temperature change. 
     A forwardmost lens (i.e., first lens  110 ) of the optical system  100 , disposed closest to the object side, may have a larger diameter than that of the other lenses. For example, the first lens  110  may be sized to be in contact with an end of the lens barrel  200 . Therefore, the first lens  110  may be aligned with an optical axis by careful adjustment or another process in a state in which the first lens  110  is disposed at the end of the lens barrel  200 . The first lens  110  may be formed for the camera module  1001  to capture an image with a wide angle. As an example, an object-side surface of the first lens  110  may generally have a convex shape. As another example, the first lens  110  may generally have negative refractive power. As yet another example, the first lens  110  may have the convex object-side surface and the negative refractive power. 
     The optical system  100  may further include another component in addition to the first to fifth lenses  110 ,  120 ,  130 ,  140  and  150 . For example, the optical system  100  may further include a filter member configured to block infrared light. However, the additional component of the optical system  100  is not limited to the filter member. For example, the optical system  100  may further include a stop disposed between the lens and the lens to control the amount of light, a spacer maintaining a constant distance between the lens and the lens, etc. 
     The optical system  100  may have a predetermined angle of view. For example, the optical system  100  may have an angle of view of 120 degrees or more to simultaneously capture an image over a wide area. However, the angle of view of the optical system  100  is not limited to 120 degrees or more. For example, the optical system  100  may have an angle of view of less than 120 degrees. 
     The lens barrel  200  may accommodate an optical system  100 . For example, the lens barrel  200  may include an accommodation space accommodating the optical system  100 . The lens barrel  200  may accommodate one or more of the first lens  110  to the fifth lens  150  included in the optical system  100 . For example, the lens barrel  200  may accommodate the second to fifth lenses  120  to  150 . 
     The lens barrel  200  may generally have a cylindrical shape. However, the lens barrel  200  is not limited to the cylindrical shape. For example, the lens barrel  200  may have a shape of a quadrangular prism, a rectangular prism, or the like based on a cross-sectional shape of the first to fifth lenses  110  to  150 . 
     There may be a plurality of lens barrels  200 . For example, the lens barrel  200  may include a first lens barrel  210  and a second lens barrel  220 . The first lens barrel  210  and the second lens barrel  220  may be made of materials that are different from each other. As an example, the first lens barrel  210  may be made of a material having low thermal conductivity or a material having low electrical conductivity, and the second lens barrel  220  may be made of a material having high thermal conductivity or a material having high electrical conductivity. As another example, the first lens barrel  210  may be made of the plastic material, and the second lens barrel  220  may be made of a metal material. 
     The first lens barrel  210  may accommodate the optical system  100  and the second lens barrel  220 . For example, the first lens barrel  210  may include a first accommodation portion  212  accommodating the optical system  100  and a second accommodation portion  214  accommodating the second lens barrel  220 . The first accommodation portion  212  and the second accommodation portion  214  may be formed as spaces independent of each other. For example, the first accommodation portion  212  may be formed in a center of the first lens barrel  210 , and the second accommodation portion  214  may be formed at a predetermined distance outward from the first accommodation portion  212 . The first accommodation portion  212  and the second accommodation portion  214  may each be formed to be elongated in a longitudinal direction of the first lens barrel  210 . The first accommodation portion  212  and the second accommodation portion  214  may be formed to have sizes or lengths that are different from each other. For example, the first accommodation portion  212  may be formed to completely penetrate through the first lens barrel  210 , and the second accommodation portion  214  may be formed to have a predetermined length from one end of the first lens barrel  210 . 
     The second lens barrel  220  may be disposed in the second accommodation portion  214  of the first lens barrel  210 . The second lens barrel  220  may be in contact with the first lens  110  which is the forwardmost lens. For example, the second lens barrel  220  may be in contact with a flange portion  112  of the first lens  110  in a state of being mounted on the second accommodation portion  214  of the first lens barrel  210 . A width B 2 W of one end of the second lens barrel  220  may have substantially the same size as that of a width LFW of the flange portion  112 . The second lens barrel  220  satisfying the above-mentioned condition may be in contact with the flange portion  112  through a sufficient area, and may thus deliver energy supplied from an external source to the first lens  110  rapidly and effectively. However, the width B 2 W of the one end of the second lens barrel  220  may not necessarily have the same size as that of the width LFW of the flange portion  112 . For example, the width B 2 W of the one end of the second lens barrel  220  may have a smaller size than the width LFW of the flange portion  112 . 
     The second lens barrel  220  may have a predetermined space in a state of being mounted in the first lens barrel  210 . For example, a concave portion  222  may be formed inside the second lens barrel  220 , and a space of a significant size may be formed between the first lens barrel  210  and the second lens barrel  220 . The concave portion  222  may be elongated upwardly from a distal end of the second lens barrel  220 . 
     The second lens barrel  220  may function as an energy transfer member. For example, the second lens barrel  220  may transfer energy generated from the energy generation unit  400  to an adjacent member. As an example, the second lens barrel  220  may be made of the material having high thermal conductivity to easily transfer thermal energy of the energy generation unit  400 . As an example, the second lens barrel  220  may be made of a material having a high vibration frequency to easily transfer vibration energy of the energy generation unit  400 . The second lens barrel  220  according to this embodiment may be made of the metal material described above. However, the material of the second lens barrel  220  is not limited to the metal. For example, the second lens barrel  220  may be made of a material having a high specific heat to maintain the absorbed thermal energy for a long time. 
     The energy generation unit  400  may generate a predetermined amount of energy. For example, the energy generation unit  400  may be a heat generation device generating the thermal energy. As a specific example, the energy generation unit  400  may be a positive temperature coefficient (PTC) heater. However, the energy generation unit  400  is not limited to the heat generation device. For example, the energy generation unit  400  may be an excitation device or piezoelectric body generating the vibration energy. 
     The energy generation unit  400  may be disposed between the first lens barrel  210  and the second lens barrel  220 . For example, the energy generation unit  400  may be disposed in the concave portion  222  of the second lens barrel  220 . The energy generation unit  400  may be in close contact with the second lens barrel  220 . For example, the energy generation unit  400  may have a shape substantially the same as that of a circular space formed by the concave portion  222  and the second accommodation portion  214 . However, the energy generation unit  400  is not limited to the shape of the space formed by the concave portion  222  and the second accommodation portion  214 . 
     The energy generation unit  400  may transfer the energy to the second lens barrel  220 . For example, the energy generation unit  400  may be in contact with the concave portion  222  of the second lens barrel  220  to transfer the thermal energy, the vibration energy and the like, generated from the energy generation unit  400 , to the second lens barrel  220 . The energy generated from the energy generation unit  400  may be transferred more effectively to the second lens barrel  220  than to the first lens barrel  210 . For example, the second lens barrel  220  may be made of a material that may receive thermal energy and the vibration energy more easily than that of the first lens barrel  210 , and most of the energy generated from the energy generation unit  400  may thus be transferred to the second lens barrel  220  or absorbed into the second lens barrel  220 . 
     The camera module  1001  may further include a component other than the components described above. For example, the camera module  1001  may further include a housing  500 , a substrate  600 , a cover member  700 , and additional components. 
     The housing  500  may accommodate or support the lens barrel  200  and the substrate  600 . For example, the housing  500  may accommodate the substrate  600  while supporting the lens barrel  200  and the substrate  600 . The housing  500  may include an upper housing  510  and a lower housing  520 . The upper housing  510  may support the lens barrel  200  and the substrate  600 , and the lower housing  520  may seal an open space of the upper housing  510 . The upper housing  510  may include a support portion  512 . The support portion  512  may be elongated downward from a top end of the upper housing  510 . The support portion  512  may be coupled to the lens barrel  200  and the substrate  600 . For example, an inner surface of the support portion  512  may be coupled to the lens barrel  200 , and a distal end of the support portion  512  may be coupled to the substrate  600 . The support portion  512  and the lens barrel  200  may be fastened to each other by press-fitting, and the support portion  512  and the substrate  600  may be coupled to each other by a fastening element such as a bolt. 
     The substrate  600  may include an electronic component required to drive the camera module  1001 . For example, the substrate  600  may be equipped with an image sensor  610 , a passive element  620 , and the like. The electronic components mounted on or embedded in the substrate  600  may be electrically connected to each other. For example, an electric circuit electrically connecting the electronic components to each other may be formed on one surface of, or within, the substrate  600 . The substrate  600  may provide power and a control signal that are necessary to drive the camera module  1001 . For example, a connection terminal  630  connected to an external power source and an external device may be formed on a rear surface of the substrate  600 . The substrate  600  may be connected to the energy generation unit  400 . For example, a power supply terminal  640  connected to power terminals  402  and  404  of the energy generation unit  400  may be formed on the one surface of the substrate  600 . The energy generation unit  400  and the power supply terminal  640  may be electrically connected to each other by a power line  642 , a flexible substrate, or the like. 
     The cover member  700  may secure the forwardmost lens to the lens barrel  200 . For example, the cover member  700  may be coupled to the lens barrel  200  while pressing an edge of the first lens  110 . The cover member  700  may be adhered or coupled to the lens barrel  200 . As an example, the cover member  700  may be adhered to the lens barrel  200  by an adhesive member. As another example, the cover member  700  may be fastened to the lens barrel  200  by screw coupling. The adhering or coupling of the cover member  700  to the lens barrel  200  may improve airtightness between the cover member  700  and the lens barrel  200 , and the fastening of the cover member  700  to the lens barrel by the screw coupling may increase adhesion between the first lens  110  and the lens barrel  200  by the cover member  700  to the lens barrel  200 . 
     The cover member  700  may be generally made of a material that is the same as or similar to that of the first lens barrel  210 . For example, the cover member  700  may be made of the plastic material. The cover member  700 , made of the material that is the same as or similar to that of the first lens barrel  210 , may be excellently coupled, adhered or fastened to the first lens barrel  210 , and may thus significantly reduce a possibility that the forwardmost lens (i.e., first lens  110 ) becomes separated from the lens barrel  200 . However, the cover member  700  is not limited to the plastic material. For example, the cover member  700  may be made of the metal material to protect the first lens  110  from the external impact. 
     An airtight member  800  may be disposed between the first lens  110  and the cover member  700 . For example, the airtight member  800  may be disposed between a step portion  117 , formed on the edge of the first lens  110 , and the cover member  700 . The airtight member  800  may be made of a material that may be elastically deformed or compressively deformed. For example, the airtight member  800  may be made of rubber, synthetic rubber, elastomer, or the like. However, the airtight member  800  is not limited to the above-mentioned materials. The airtight member  800  may block a gap between the first lens  110  and the cover member  700 . For example, the airtight member  800  may be elastically deformed when the cover member  700  and the lens barrel  200  are coupled to each other to block the gap between the first lens  110  and the cover member  700 . 
     The camera module  1001  configured as above may remove foreign matter adhering to the forwardmost lens (i.e., first lens  110 ). For example, the camera module  1001  may remove frost, moisture, dew, raindrops, or the like, adhering to the surface of the first lens  110  by using vibrations, heat, static electricity, etc. 
     The following description describes a method of removing the foreign matter from the camera module  1001 , according to an embodiment. 
     The camera module  1001  may remove the foreign matter adhering to or occurring on the surface of the forwardmost lens (i.e., first lens  110 ) by using the energy generation unit  400 . 
     As an example, the camera module  1001  may remove the foreign matter adhering to or occurring on the surface of the forwardmost lens (i.e., first lens  110 ) by always operating the energy generation unit  400  regardless of an external environment. As another example, the camera module  1001  may heat the first lens  110  by operating the energy generation unit  400  when it is recognized that a resolution value obtained by the image sensor  610  is a reference value or less. 
     In the case in which the energy generation unit  400  is operated regardless of the external environment, the energy generation unit  400  may be operated continuously or constantly to generate the thermal energy. For example, the energy generation unit  400  may generate the thermal energy at a predetermined time interval or may generate the thermal energy for its adjacent component (e.g., the second lens barrel  220 ) to maintain a constant temperature. In the case in which the energy generation unit  400  is operated when it is recognized that a resolution value obtained by the image sensor  610  is a reference value or less, the energy generation unit  400  may generate the thermal energy by being operated by an external signal. 
     The thermal energy of the energy generation unit  400  may be transferred to its adjacent components. For example, the thermal energy of the energy generation unit  400  may be transferred to the first lens barrel  210  and the second lens barrel  220  surrounding the energy generation unit  400  in the form of convection, conduction, radiation, etc. The thermal energy of the energy generation unit  400  may be transferred to the second lens barrel  220 . For example, the second lens barrel  220  may be made of the material having higher thermal conductivity than that of the first lens barrel  210 , and most of the thermal energy of the energy generation unit  400  may be transferred to the second lens barrel  220 . The thermal energy transferred to the second lens barrel  220  may be transferred to the first lens  110 , which is in contact with or adjacent to the second lens barrel  220 , while simultaneously heating the second lens barrel  220 . The thermal energy transferred to the first lens  110  may heat the first lens  110  to a predetermined temperature to evaporate raindrop, water droplet, frost or the like adhering to the surface of the first lens  110 . In addition, the first lens  110  being heated to the predetermined temperature may cause a convection phenomenon in the vicinity of the first lens  110  to induce removal of dust attached to the surface of the first lens  110  or to prevent the dust from adhering to the surface of the first lens  110  in advance. 
     As described above, the camera module  1001  may use the energy generation unit  400  to remove raindrop, water droplet, frost, moisture, dust or the like adhering to the surface of the forwardmost lens, thereby preventing resolution degradation, distortion of a field of view of an image being captured or the like, due to the foreign matter. 
       FIGS. 2 to 4  illustrate modified examples in which a second lens barrel and an energy generation unit are coupled to each other for effectively transferring the energy of the energy generation unit. 
     Referring to  FIGS. 2 to 4 , a second lens barrel and an energy generation unit may be formed to increase energy transfer efficiency. For example, the second lens barrel and the energy generation unit may increase an area in which the second lens barrel and the energy generation unit are in contact with or face each other. 
     Referring to  FIG. 2 , as an example, a second lens barrel  220 - 1  and an energy generation unit  400 - 1  may have a plurality of steps  226  and  416 , respectively, as shown in  FIG. 2 . Referring to  FIG. 3 , as another example, a second lens barrel  220 - 2  and an energy generation unit  400 - 2  may have a plurality of grooves  227  and protrusions  417 , respectively. Referring to  FIG. 4 , as another example, a second lens barrel  220 - 3  may have the steps  226  and the grooves  227  and an energy generation unit  400 - 3  may have the steps  416  and the protrusions  417 . 
     In the embodiment illustrated in  FIG. 2 , the second lens barrel  220 - 1  and the energy generation unit  400 - 1  may each have a step difference. For example, the second lens barrel  220 - 1  may have the plurality of steps  226  formed on an inner circumferential surface  225 , and the energy generation unit  400 - 1  may have the plurality of steps  416  formed on an outer circumferential surface  415 . In general, the inner circumferential surfaces  225  and steps  226  of the second lens barrel  220 - 1  may be in contact with the outer circumferential surfaces  415  and steps  416  of the energy generation unit  400 - 1 . As an example, the inner circumferential surfaces  225  of the second lens barrel  220 - 1  may be in contact with the outer circumferential surfaces  415  of the energy generation unit  400 - 1 , and the steps  226  of the second lens barrel  220 - 1  may be in contact with the steps  416  of the energy generation unit  400 - 1 , respectively. As another example, the inner circumferential surface  225  of the second lens barrel  220 - 1  may have substantially the same size (or diameter) as that of the outer circumferential surface  415  of the energy generation unit  400 - 1 , and the step  226  of the second lens barrel  220 - 1  may have substantially the same size as that of the step  416  of the energy generation unit  400 - 1 . 
     The second lens barrel  220 - 1  may have a cross-sectional area that is increased in an upward direction (i.e., toward the first lens  110 ). For example, thicknesses BT 1 , BT 2 , BT 3  and BT 4  of the second lens barrel  220  may be increased in the upward direction. The energy generation unit  400 - 1  may have a cross-sectional area that is decreased in the upward direction. For example, thicknesses WH 1 , WH 2  and WH 3  of the energy generation unit  400 - 1  may be decreased in the upward direction. 
     The second lens barrel  220 - 1  and the energy generation unit  400 - 1  may easily transfer the energy generated by the heat generation unit  400 - 1  upward. For example, the second lens barrel  220 - 1  may have the cross-sectional area that is increased in the upward direction, and the lower the portion of the second lens barrel  220 - 1 , the faster the energy of the energy generation unit  400  may be absorbed or transferred. In contrast, the energy generation unit  400 - 1  may have the cross-sectional area that is increased in the downward direction, and the lower the portion of the energy generation unit  400 - 1 , the greater the energy that may be generated. 
     In consideration of the description above, the energy generated from the energy generation unit  400 - 1  may not only be rapidly transferred, but may also be increased toward the lower portion of the second lens barrel  220 - 1 . Meanwhile, the energy has a tendency to be moved from a place having a high displacement to a place having a low displacement, and the energy transferred to the second lens barrel  220 - 1  may thus be moved from its lower portion to its upper portion. Therefore, the energy of the energy generation unit  400 - 1  may be rapidly transferred or supplied to the first lens  110 , which is the forwardmost lens. 
     Referring to  FIG. 3 , the second lens barrel  220 - 2  and the energy generation unit  400 - 2  may each have the grooves  227  and the protrusions  417 . For example, the second lens barrel  220 - 2  may have the plurality of grooves  227  formed in the inner circumferential surface  225 , and the energy generation unit  400 - 2  may have the plurality of protrusions  417  formed on the outer circumferential surface  415 . The second lens barrel  220 - 2  may generally be mesh-coupled to the energy generation unit  400 - 2 . As an example, the inner circumferential surfaces  225  of the second lens barrel  220 - 2  may be in contact with the outer circumferential surfaces  415  of the energy generation unit  400 - 2 , and the grooves  227  of the second lens barrel  220 - 2  may be in mesh contact with the protrusions  417  of the energy generation unit  400 . 
     The second lens barrel  220 - 2  and the energy generation unit  400 - 2  may have an increased area in which the second lens barrel  220 - 2  and the energy generation unit  400 - 2  are in contact with or face each other by the grooves  227  and the protrusions  417 , thus improving the energy transfer efficiency through the conduction or the convection. 
     Referring to  FIG. 4 , the second lens barrel  220 - 3  and the energy generation unit  400 - 3  may have all the features shown in  FIGS. 2 and 3 . For example, the second lens barrel  220 - 3  may have the steps  226  and the grooves  227 , and the energy generation unit  400 - 3  may have the steps  416  and the protrusions  417 . Therefore, the second lens barrel  220 - 3  and energy generation unit  400 - 3  may have all the advantages of the lens barrels  220 - 1  and  220 - 2 , and the energy generation units  400 - 1  and  400 - 2 , shown in  FIGS. 2 and 3 . 
       FIGS. 5A through 6B  illustrate modified examples in which a forwardmost lens and a second lens barrel are coupled to each other. 
     A first lens  110 , which is the forwardmost lens, and a second lens barrel may be self-aligned with each other. As an example, a first lens  110 - 1  and a second lens barrel  220 - 4  may be aligned with each other by allowing their inclined surfaces to be in line contact with each other as shown in  FIGS. 5A and 5B . As another example, a first lens  110 - 2  and a second lens barrel  220 - 5  may be aligned with each other by coupling a protrusion  118  and a groove  228  to each other, as shown in  FIGS. 6A and 6B . 
     Referring to  FIGS. 5A and 5B , the first lens  110 - 1  and the second lens barrel  220 - 4  may include inclined surfaces  114  and  224 , respectively, having a predetermined inclination with respect to bonding surfaces  112   a  and  112   b  of the first lens  110 - 1 , and bonding surfaces  221   a  and  221   b  of the second lens barrel  220 - 4 , respectively. For example, the first lens  110 - 1  may include the inclined surface  114  having a first inclination angle θ 1  with respect to the bonding surface  112   b , and the second lens barrel  220 - 4  may include the inclined surface  224  having a second inclination angle θ 2  with respect to the bonding surface  221   a . The inclined surface  114  of the first lens  110 - 1  and the inclined surface  224  of the second lens barrel  220 - 4  may be generally parallel to each other. However, the inclined surface  114  of the first lens  110 - 1  and the inclined surface  224  of the second lens barrel  220 - 4  may not be necessarily parallel to each other. 
     The inclined surface  114  of the first lens  110 - 1  and the inclined surface  224  of the second lens barrel  220 - 4  may each have a predetermined height. For example, the inclined surface  114  of the first lens  110 - 1  may have a first height h 1 , and the inclined surface  224  of the second lens barrel  220 - 4  may have a second height h 2 . The inclined surface  114  of the first lens  110  and the inclined surface  224  of the second lens barrel  220  may have substantially the same height. For example, the first height h 1  of the inclined surface  114  and the second height h 2  of the inclined surface  224  may have the same size. However, the inclined surface  114  of the first lens  110 - 1  and the inclined surface  224  of the second lens barrel  220 - 4  may not necessarily have the same height. 
     The first lens  110 - 1  and the second lens barrel  220 - 4  may be aligned with each other by coupling the inclined surface  114  and the inclined surface  224  to each other. For example, a rotation center (or optical axis C) of the first lens  110 - 1  and a rotation center of the second lens barrel  220 - 4  may be aligned with each other by arranging the inclined surface  114  and the inclined surface  224  to be in line contact or surface contact with each other. 
     Therefore, the first lens  110 - 1  and the second lens barrel  220 - 4  may solve a problem in which the resolution of a camera module is degraded because a first lens is not aligned with the optical axis. 
     The first lens  110 - 1  and the second lens barrel  220 - 4  may be coupled to each other by the bonding surfaces  112   a ,  112   b ,  221   a  and  221   b . For example, the first lens  110 - 1  and the second lens barrel  220 - 4  may be aligned with each other by arranging the inclined surfaces  114  and  224  to be in contact with each other, while being closely adhered to each other by simultaneously arranging the bonding surfaces  112   a ,  112   b ,  221   a  and  221   b  to be in surface contact with each other. The first lens  110 - 1  and the second lens barrel  220 - 4  may be bonded to each in a configuration in which the bonding surfaces  112   a  and  221   a  are bonded to each other and/or the bonding surfaces  112   b  and  221   b  are bonded to each other. As an example, in a case in which the inclined surface  114  and the inclined surface  224  have the same height (i.e., when h 1 =h 2 ), the bonding surfaces  112   a  and  221   a  may be closely bonded to each other and the bonding surfaces  112   b  and  221   b  may be closely bonded to each other. As another example, in a case in which the inclined surface  114  and the inclined surface  224  have heights different from each other (i.e., when h 1 &gt;h 2  or h 1 &lt;h 2 ), either the bonding surfaces  112   a  and  221   a  may be closely bonded to each other or the bonding surfaces  112   b  and  221   b  may be closely bonded to each. 
     Accordingly, the first lens  110 - 1  and the second lens barrel  220 - 4  may be configured such that the first lens  110 - 1  and the second lens barrel  220 - 4  are be self-aligned with each other, while simultaneously allowing energy of an energy generation unit to be transferred by arranging the first lens  110 - 1  and the second lens barrel  220 - 4  be in close contact with each other. 
     Referring to  FIGS. 6A and 6B , the first lens  110 - 2  and the second lens barrel  220 - 5  may respectively include protrusions  118  and grooves  228 . For example, the first lens  110 - 2  may include the protrusion  118  protruding downwardly from the bonding surface  112 , and the second lens barrel  220 - 5  may include the groove  228  formed in the bonding surface  221 . 
     The protrusion  118  and the groove  228  each may generally have a hemispherical shape. For example, the protrusion  118  may have an embossed hemispherical shape having a radius of R 1 , and the groove  228  may have an engraved hemispherical shape having a radius of R 2 . The radius R 1  of the protrusion  118  and the radius R 2  of the groove  228  may substantially have the same size. However, the radius R 1  of the protrusion  118  and the radius R 2  of the groove  228  may not necessarily have the same size. For example, the radius R 1  of the protrusion  118  may be smaller than the radius R 2  of the groove  228 . In a case in which the radius R 1  of the protrusion  118  and the radius R 2  of the groove  228  do not have the same size, a height of the protrusion  118  may be greater than a depth of the groove  228 . The protrusion  118  and the groove  228  may each have a predetermined height and depth. For example, Ph may indicate the height of the protrusion  118 , and Dp may indicate the depth of the groove  228 . The height Ph of the protrusion  118  and the depth Dp of the groove  228  may have substantially the same size. However, the height Ph of the protrusion  118  and the depth Dp of the groove  228  may not necessarily have the same size. For example, the height Ph of the protrusion  118  may be less than the depth Dp of the groove  228 . In the former case, the radius R 1  of the protrusion  118  may be greater than the radius R 2  of the groove  228 . 
     The first lens  110 - 2  and the second lens barrel  220 - 5  may be aligned with each other by coupling the protrusion  118  and the groove  228  to each other. For example, the rotation center (or optical axis C) of the first lens  110 - 2  and the rotation center of the second lens barrel  220 - 5  may be aligned with each other by arranging the protrusion  118  and the groove  228  to be in line contact or surface contact with each other. Therefore, the first lens  110 - 2  and the second lens barrel  220 - 5  may solve a problem in which the resolution of a camera module is degraded because the first lens  110  is not aligned with the optical axis. In addition, the first lens  110 - 2  and the second lens barrel  220 - 5  may have improved reliability of bonding the first lens  110 - 2  and the second lens barrel  220 - 5  to each other by fastening the protrusion  118  and the groove  228  to each other. 
     For reference, although not described or shown in the present specification or the drawings, the second lens barrels  220 - 4  and  220 - 5  shown in  FIGS. 5A through 6B  may be modified to include one or more of the features shown in  FIGS. 2 through 4 . As an example, the second lens barrel  220 - 4  shown in  FIGS. 5A and 5B  may further include the feature of the second lens barrel  220 - 1  shown in  FIG. 2 . As another example, the second lens barrel  220 - 5  shown in  FIGS. 6A and 6B  may further include the feature of the second lens barrel  220 - 2  shown in  FIG. 3 . As yet another example, the second lens barrel  220 - 4  shown in  FIGS. 5A and 5B  may further include the feature of the second lens barrel  220 - 2  shown in  FIG. 3  or the feature of the second lens barrel  220 - 3  shown in  4 . 
       FIG. 7  shows another camera module, according to an embodiment. 
     Referring to  FIG. 7 , a camera module  1002  may include the optical system  100 , the lens barrel  200 , the energy generation unit  400 , and a buffer member  230 . 
     The optical system  100  may form an image at the predetermined position by using the light reflected from a subject. For example, the optical system  100  may have the refractive power to form the image at the predetermined position by using the light incident thereon. The optical system  100  may include the plurality of lenses. For example, the optical system  100  may include the five or more lenses including the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , and the fifth lens  150 . However, the number of lenses included in the optical system  100  is not limited to five. For example, the optical system  100  may include four or fewer lenses or include six or more lenses. 
     The forwardmost lens (i.e., the first lens  110 ) of the optical system  100 , which is disposed closest to the object side, may have a diameter larger than that of the other lenses. For example, the first lens  110  may be sized to be in contact with the end of the lens barrel  200 . Therefore, the first lens  110  may be aligned with the optical axis by the careful adjustment or another process in the state in which the first lens  110  is disposed at the end of the lens barrel  200 . The first lens  110  may be formed for the camera module  1002  to capture the image with a wide angle. As an example, the object-side surface of the first lens  110  may generally have a convex shape. As another example, the first lens  110  may generally have a negative refractive power. 
     The optical system  100  may further include another component in addition to the first to fifth lenses  110 ,  120 ,  130 ,  140 , and  150 . For example, the optical system  100  may further include the filter member configured to block the infrared light. However, the additional component of the optical system  100  is not limited to the filter member. For example, the optical system  100  may further include the stop disposed between the lens and the lens to control the amount of light, and the spacer maintaining a constant distance between the lens and the lens, etc. 
     The optical system  100  may have a predetermined angle of view. For example, the optical system  100  may have an angle of view of 120 degrees or more to simultaneously capture an image over a wide area. However, the angle of view of the optical system  100  is not limited to 120 degrees or more. For example, the optical system  100  may have an angle of view of less than 120 degrees. 
     The lens barrel  200  may accommodate the optical system  100 . For example, the lens barrel  200  may include the accommodation space accommodating the optical system  100 . The lens barrel  200  may accommodate one or more of the first to fifth lenses  110 ,  120 ,  130 ,  140 , and  150  included in the optical system  100 . For example, the lens barrel  200  may accommodate the second to fifth lenses  120  to  150 . 
     The lens barrel  200  may generally have a cylindrical shape. However, the lens barrel  200  is not limited to the cylindrical shape. For example, the lens barrel  200  may have the shape of a quadrangular prism, a rectangular prism, or the like, based on a cross-sectional shape of the lenses. 
     There may be a plurality of lens barrels  200 . For example, the lens barrel  200  may include the first lens barrel  210  and the second lens barrel  220 . The first lens barrel  210  and the second lens barrel  220  may be made of materials different from each other. As an example, the first lens barrel  210  may be made of a material having low thermal conductivity or the material having low electrical conductivity, and the second lens barrel  220  may be made of the material having high thermal conductivity or the material having high electrical conductivity. As another example, the first lens barrel  210  may be made of the plastic material, and the second lens barrel  220  may be made of the metal material. 
     The first lens barrel  210  may accommodate the optical system  100  and the second lens barrel  220 . For example, the first lens barrel  210  may include the first accommodation portion  212  accommodating the optical system  100  and the second accommodation portion  214  accommodating the second lens barrel  220 . The first accommodation portion  212  and the second accommodation portion  214  may be formed as the spaces independent of each other. For example, the first accommodation portion  212  may be formed in the center of the first lens barrel  210 , and the second accommodation portion  214  may be formed at the predetermined distance outward from the first accommodation portion  212 . The first accommodation portion  212  and the second accommodation portion  214  may each be formed to be elongated in the longitudinal direction of the first lens barrel  210 . The first accommodation portion  212  and the second accommodation portion  214  may be formed to have the sizes or lengths different from each other. For example, the first accommodation portion  212  may be formed to completely penetrate through the first lens barrel  210 , and the second accommodation portion  214  may be formed to have the predetermined length from one end of the first lens barrel  210 . 
     The second lens barrel  220  may be disposed in the second accommodation portion  214  of the first lens barrel  210 . The second lens barrel  220  may be in contact with the first lens  110 , which is the forwardmost lens. For example, one end  221  of the second lens barrel  220  may be in contact with the flange portion  112  of the first lens  110 . 
     The second lens barrel  220  may have the predetermined space in the state of being mounted in the first lens barrel  210 . For example, the concave portion  222  may be formed inside the second lens barrel  220 , and the space of a significant size may be formed between the first lens barrel  210  and the second lens barrel  220 . The concave portion  222  may be elongated upwardly from the distal end of the second lens barrel  220 . 
     The second lens barrel  220  may function as the energy transfer member. In more detail, the second lens barrel  220  may transfer the energy generated by the energy generation unit  400  to the adjacent member. As an example, the second lens barrel  220  may be made of the material having high thermal conductivity to easily transfer the thermal energy of the energy generation unit  400 . As an example, the second lens barrel  220  may be made of the material having a high vibration frequency to easily transfer the vibration energy of the energy generation unit  400 . The second lens barrel  220  according to this embodiment may be made of the metal material described above. However, the material of the second lens barrel  220  is not limited to the metal. For example, the second lens barrel  220  may be made of the material having a high specific heat to maintain the absorbed thermal energy for a long time. 
     The energy generation unit  400  may generate a predetermined amount of energy. For example, the energy generation unit  400  may be the heat generation device configured to generate the thermal energy. As an example, the energy generation unit  400  may be the positive temperature coefficient (PTC) heater. However, the energy generation unit  400  is not limited to the heat generation device. For example, the energy generation unit  400  may be the excitation device or the piezoelectric body configured to generate the vibration energy. 
     The energy generation unit  400  may be disposed between the first lens barrel  210  and the second lens barrel  220 . For example, the energy generation unit  400  may be disposed in the concave portion  222  of the second lens barrel  220 . The energy generation unit  400  may be in close contact with the second lens barrel  220 . For example, the energy generation unit  400  may have the shape substantially the same as that of the circular space formed by the concave portion  222  and the second accommodation portion  214 . However, the energy generation unit  400  is not limited to the shape of the space formed by the concave portion  222  and the second accommodation portion  214 . 
     The energy generation unit  400  may transfer the energy to the second lens barrel  220 . For example, the energy generation unit  400  may be in contact with the concave portion  222  of the second lens barrel  220  to transfer the thermal energy, the vibration energy, and the like, generated by the energy generation unit  400 , to the second lens barrel  220 . The energy generated by the energy generation unit  400  may be transferred more effectively to the second lens barrel  220  than to the first lens barrel  210 . For example, the second lens barrel  220  may be made of the material that may receive the thermal energy, the vibration energy, and the like more easily than that of the first lens barrel  210 , and most of the energy generated from the energy generation unit  400  may thus be transferred to the second lens barrel  220  or absorbed into the second lens barrel  220 . 
     The buffer member  230  may be disposed between the first lens barrel  210  and the second lens barrel  220 . For example, the buffer member  230  may be disposed in the concave portion  222  of the second lens barrel  220 . The buffer member  230  may be made of the material that may be elastically deformed or compressively deformed. In addition, the buffer member  230  may be made of a material having strong restoring force. For example, the buffer member  230  may be made of rubber, synthetic rubber, elastomer or the like. 
     The buffer member  230  may allow the second lens barrel  220  and the energy generation unit  400  to be in close contact with each other. As an example, the buffer member  230  may be disposed between the first lens barrel  210  and the energy generation unit  400  to provide elastic force pressing the energy generation unit  400  toward the concave portion  222 . As another example, the buffer member  230  may be disposed between the first lens barrel  210  and the second lens barrel  220  to provide elastic force pressing the second lens barrel  220  toward the flange portion  112  of the first lens  110 . 
     A volume of the buffer member  230  may be larger than a volume of a space formed between the lens barrels  210  and  220  and the energy generation unit  400  to achieve the above-described effect. For example, as shown in  FIGS. 8A through 8C , the widths Ew 1  and Ew 2  and heights Eh 1  and Eh 2  of the buffer member  230  may be greater than the widths Sw 1  and Sw 2  and heights Sh 1  and Sh 2  of an arrangement space  216  formed between the lens barrels  210  and  220  and the energy generation unit  400 . For example, the widths Ew 1  and Ew 2  of the buffer member  230  may be greater than the widths Sw 1  and Sw 2  of the arrangement space  216 , and the heights Eh 1  and Eh 2  of the buffer member  230  may be greater than the heights Sh 1  and Sh 2  of the arrangement space  216 . Accordingly, the buffer member  230 , when inserted into the arrangement space  216 , may be compressed or elastically deformed by a deviation between the volume of the buffer member  230  and that of the arrangement space  216 . In addition, the restoring force accumulated by compressing or elastically deforming the buffer member  230  may act as force applied to the energy generation unit  400  to be in close contact with the second lens barrel  220  or the second lens barrel  220  to be in close contact with the first lens  110 , as shown in  FIG. 8C . Therefore, the camera module  1002  may transfer most of the energy generated by the energy generation unit  400  to the first lens  110  without loss due to a space between the energy generation unit  400  and the second lens barrel  220  or a space between the second lens barrel  220  and the first lens  110 . 
     The camera module  1002  may further include a component other than the components described above. For example, the camera module  1001  may further include the housing  500 , the substrate  600 , the cover member  700 , etc. 
     The housing  500  may accommodate or support the lens barrel  200  and the substrate  600 . For example, the housing  500  may accommodate the substrate  600  while supporting the lens barrel  200  and the substrate  600 . The housing  500  may include the upper housing  510  and the lower housing  520 . The upper housing  510  may support the lens barrel  200  and the substrate  600 , and the lower housing  520  may seal the open space of the upper housing  510 . The upper housing  510  may include the support portion  512 . The support portion  512  may be elongated downward from the top end of the upper housing  510 . The support portion  512  may be coupled to the lens barrel  200  and the substrate  600 . For example, the inner surface of the support portion  512  may be coupled to the lens barrel  200 , and the distal end of the support portion  512  may be coupled to the substrate  600 . The support portion  512  and the lens barrel  200  may be fastened to each other by the press-fit, and the support portion  512  and the substrate  600  may be coupled to each other by using the fastening element such as a bolt. 
     The substrate  600  may include an electronic component required to drive the camera module  1002 . For example, the substrate  600  may be equipped with the image sensor  610 , the passive element  620 , and the like. The electronic components mounted on or embedded in the substrate  600  may be electrically connected to each other. For example, the electric circuit electrically connecting the electronic components to each other may be formed on the one surface of or in the substrate  600 . The substrate  600  may provide power and a control signal, necessary to drive the camera module  1002 . For example, the connection terminal  630  connected to the external power source and the external device may be formed on the rear surface of the substrate  600 . The substrate  600  may be connected to the energy generation unit  400 . For example, the power supply terminal  640 , which is connected to the power terminals  402  and  404  of the energy generation unit  400 , may be formed on the one surface of the substrate  600 . The energy generation unit  400  and the power supply terminal  640  may be electrically connected to each other by the power line  642 , the flexible substrate, or the like. 
     The cover member  700  may secure the forwardmost lens to the lens barrel  200 . For example, the cover member  700  may be coupled to the lens barrel  200  while pressing the edge of the first lens  110 . The cover member  700  may be adhered or coupled to the lens barrel  200 . As an example, the cover member  700  may be adhered to the lens barrel  200  by the adhesive member. As another example, the cover member  700  may be fastened to the lens barrel  200  by a screw coupling. The example in which the cover member  700  is adhered to the lens barrel  200  by the adhesive member may improve the airtightness between the cover member  700  and the lens barrel  200 , and the example in which the cover member  700  is fastened to the lens barrel  200  by the screw coupling may increase the adhesion between the first lens  110  and the lens barrel  200  by the cover member  700 . 
     The cover member  700  may be generally made of the material that is the same as or similar to that of the first lens barrel  210 . For example, the cover member  700  may be made of the plastic material. The cover member  700 , when made of the material that is the same as or similar to that of the first lens barrel  210 , may be excellently coupled, adhered, or fastened to the first lens barrel  210 , and may thus significantly reduce the possibility that the forwardmost lens (i.e., first lens  110 ) becomes separated from the lens barrel  200 . However, the cover member  700  is not limited to the plastic material. For example, the cover member  700  may be made of the metal material to protect the first lens  110  from the external impact. 
     The airtight member  800  may be disposed between the first lens  110  and the cover member  700 . For example, the airtight member  800  may be disposed between the step portion  117 , formed on the edge of the first lens  110 , and the cover member  700 . The airtight member  800  may be made of the material that may be elastically deformed or compressively deformed. For example, the airtight member  800  may be made of rubber, synthetic rubber, elastomer or the like. However, the airtight member  800  is not limited to the above-mentioned material. The airtight member  800  may block the gap between the first lens  110  and the cover member  700 . For example, the airtight member  800  may be elastically deformed when the cover member  700  and the lens barrel  200  are coupled to each other to block the gap between the first lens  110  and the cover member  700 . 
     The camera module  1002  may remove the foreign matter adhering to the forwardmost lens (i.e., first lens  110 ). For example, the camera module  1002  may remove raindrop on the first lens  110  in rain, frost, or dew occurring on the surface of the first lens  110  due to a difference between day and night temperatures, dust adhering to the surface of the first lens  110 , etc. 
     In addition, the camera module  1002  may strengthen the adhesion between the second lens barrel  220  and the energy generation unit  400  and the second lens barrel  220  and the first lens  110  by including the buffer member  230 . Therefore, the camera module  1002  may rapidly transfer the energy of the energy generation unit  400  to the second lens barrel  220  and the first lens  110 . 
     For reference, although not described or shown in the present specification or the drawings, the first lens  110 , the second lens barrel  220  and the energy generation unit  400  may be deformed into the shapes shown in  FIGS. 2 through 6B . As an example, the second lens barrel  220  and the energy generation unit  400 , shown in  FIG. 7 , may be deformed into the shapes shown in  FIGS. 2 through 4 . As another example, the first lens  110  and the second lens barrel  220 , shown in  FIG. 7 , may be deformed into the shapes shown in FIGS.  5 A through  6 B. As yet another example, the second lens barrel  220  shown in  FIG. 7  may be coupled to the first lens  110  having the shape shown in  FIGS. 5A through 6B  while being coupled to the energy generation unit  400  having the shape shown in  FIGS. 2 through 4 . 
       FIG. 9  illustrates a camera module, according to another embodiment. 
     Referring to  FIG. 9 , a camera module  1003  may include the optical system  100 , the lens barrel  200 , the energy generation unit  400 , and an insulation member  240 . 
     The optical system  100  may form an image at the predetermined position by using the light reflected from a subject. For example, the optical system  100  may have the refractive power to form the image at the predetermined position by using the light incident thereon. The optical system  100  may include the plurality of lenses. For example, the optical system  100  may include five or more lenses including the first to fifth lenses  110 ,  120 ,  130 ,  140 , and  150 . However, the number of lenses included in the optical system  100  is not limited to five. For example, the optical system  100  may include four or fewer lenses or include six or more lenses. 
     The forwardmost lens (i.e., first lens  110 ) of the optical system  100 , disposed closest to the object side, may have a larger diameter than the other lenses. For example, the first lens  110  may be sized to be in contact with the end of the lens barrel  200 . Therefore, the first lens  110  may be aligned with the optical axis by the careful adjustment or another process in the state in which the first lens  110  is disposed at the end of the lens barrel  200 . The first lens  110  may be formed for the camera module  1003  to capture the image with a wide angle. As an example, the object-side surface of the first lens  110  may generally have a convex shape. As another example, the first lens  110  may generally have a negative refractive power. 
     The optical system  100  may further include another component in addition to the first to fifth lenses  110 ,  120 ,  130 ,  140 , and  150 . For example, the optical system  100  may further include the filter member configured to block the infrared light. However, the additional component of the optical system  100  is not limited to the filter member. For example, the optical system  100  may further include the stop disposed between the lens and the lens to control the amount of light, the spacer maintaining a constant distance between the lens and the lens, etc. 
     The optical system  100  may have a predetermined angle of view. For example, the optical system  100  may have an angle of view of 120 degrees or more to simultaneously capture the image over a wide area. However, the angle of view of the optical system  100  is not limited to 120 degrees or more. For example, the optical system  100  may have an angle of view of less than 120 degrees. 
     The lens barrel  200  may accommodate the optical system  100 . For example, the lens barrel  200  may include the accommodation space accommodating the optical system  100 . The lens barrel  200  may accommodate one or more of the first to fifth lenses  110  to  150  included in the optical system  100 . For example, the lens barrel  200  may accommodate the second to fifth lenses  120  to  150 . 
     The lens barrel  200  may generally have a cylindrical shape. However, the lens barrel  200  is not limited to the cylindrical shape. For example, the lens barrel  200  may have the shape of a quadrangular prism, a rectangular prism, or the like, based on a cross-sectional shape of the lenses. 
     There may be the plurality of lens barrels  200 . For example, the lens barrel  200  may include the first lens barrel  210  and the second lens barrel  220 . The first lens barrel  210  and the second lens barrel  220  may be made of materials different from each other. As an example, the first lens barrel  210  may be made of the material having low thermal conductivity or the material having low electrical conductivity, and the second lens barrel  220  may be made of the material having high thermal conductivity or the material having high electrical conductivity. As another example, the first lens barrel  210  may be made of the plastic material, and the second lens barrel  220  may be made of the metal material. 
     The first lens barrel  210  may accommodate the optical system  100  and the second lens barrel  220 . For example, the first lens barrel  210  may include the first accommodation portion  212  accommodating the optical system  100  and the second accommodation portion  214  accommodating the second lens barrel  220 . The first accommodation portion  212  and the second accommodation portion  214  may be formed as the spaces independent of each other. For example, the first accommodation portion  212  may be formed in the center of the first lens barrel  210 , and the second accommodation portion  214  may be formed at the predetermined distance outward from the first accommodation portion  212 . The first accommodation portion  212  and the second accommodation portion  214  may each be formed to be elongated in the longitudinal direction of the first lens barrel  210 . The first accommodation portion  212  and the second accommodation portion  214  may be formed to have the sizes or lengths different from each other. For example, the first accommodation portion  212  may be formed to completely penetrate through the first lens barrel  210 , and the second accommodation portion  214  may be formed to have the predetermined length from one end of the first lens barrel  210 . 
     The second lens barrel  220  may be disposed in the second accommodation portion  214  of the first lens barrel  210 . The second lens barrel  220  may be in contact with the first lens  110 , which is the forwardmost lens. For example, the one end  221  of the second lens barrel  220  may be in contact with the flange portion  112  of the first lens  110 . 
     The second lens barrel  220  may have the predetermined space in the state of being mounted in the first lens barrel  210 . For example, the concave portion  222  may be formed inside the second lens barrel  220 , and the space of a significant size may be formed between the first lens barrel  210  and the second lens barrel  220 . The concave portion  222  may be elongated upwardly from the distal end of the second lens barrel  220 . 
     The second lens barrel  220  may function as the energy transfer member. In more detail, the second lens barrel  220  may transfer the energy generated by the energy generation unit  400  to the adjacent member. As an example, the second lens barrel  220  may be made of the material having high thermal conductivity to easily transfer the thermal energy of the energy generation unit  400 . As an example, the second lens barrel  220  may be made of the material having a high vibration frequency to easily transfer the vibration energy of the energy generation unit  400 . The second lens barrel  220  may be made of the metal material described above. However, the material of the second lens barrel  220  is not limited to the metal. For example, the second lens barrel  220  may be made of the material having a high specific heat to maintain the absorbed thermal energy for a long time. 
     The energy generation unit  400  may generate a predetermined amount of energy. For example, the energy generation unit  400  may be the heat generation device configured to generate the thermal energy. For example, the energy generation unit  400  may be the positive temperature coefficient (PTC) heater. However, the energy generation unit  400  is not limited to the heat generation device. For example, the energy generation unit  400  may be the excitation device or piezoelectric body configured to generate the vibration energy. 
     The energy generation unit  400  may be disposed between the first lens barrel  210  and the second lens barrel  220 . For example, the energy generation unit  400  may be disposed in the concave portion  222  of the second lens barrel  220 . The energy generation unit  400  may be in close contact with the second lens barrel  220 . For example, the energy generation unit  400  may have a shape substantially the same as that of the circular space formed by the concave portion  222  and the second accommodation portion  214 . However, the energy generation unit  400  is not limited to the shape of the space formed by the concave portion  222  and the second accommodation portion  214 . 
     The energy generation unit  400  may transfer energy to the second lens barrel  220 . For example, the energy generation unit  400  may be in contact with the concave portion  222  of the second lens barrel  220  to transfer the thermal energy, the vibration energy, and the like, generated by the energy generation unit  400 , to the second lens barrel  220 . The energy generated by the energy generation unit  400  may be transferred more effectively to the second lens barrel  220  than to the first lens barrel  210 . For example, the second lens barrel  220  may be made of the material which may receive the thermal energy, the vibration energy, and the like more easily than that of the first lens barrel  210 , and most of the energy generated by the energy generation unit  400  may thus be transferred to the second lens barrel  220  or absorbed into the second lens barrel  220 . 
     The insulation member  240  may be disposed between the first lens barrel  210  and the second lens barrel  220 . For example, the insulation member  240  may be disposed in the concave portion  222  of the second lens barrel  220 . The insulation member  240  may be made of a material having low thermal conductivity. For example, the insulation member  240  may be made of glass, ceramic, expanded polystyrene, expanded polyurethane, polyethylene, or the like, or may be made of a synthetic material including one or more of the materials described above. 
     The insulation member  240  may improve heating efficiency of the second lens barrel  220 . For example, the insulation member  240  may block the thermal energy of the energy generation unit  400  from being transferred toward the first lens barrel  210 , thereby allowing most of the thermal energy generated by the energy generation unit  400  to be transferred to the second lens barrel  220 . 
     Therefore, the camera module  1003  may improve the heating efficiency of the second lens barrel  220  by including the insulation member  240  and a heating rate of the first lens  110  by including the second lens barrel  220 . 
     The camera module  1003  may further include a component other than the components described above. For example, the camera module  1001  may further include the housing  500 , the substrate  600 , the cover member  700 , etc. 
     The housing  500  may accommodate or support the lens barrel  200  and the substrate  600 . For example, the housing  500  may accommodate the substrate  600  while supporting the lens barrel  200  and the substrate  600 . The housing  500  may include the upper housing  510  and the lower housing  520 . The upper housing  510  may support the lens barrel  200  and the substrate  600 , and the lower housing  520  may seal the open space of the upper housing  510 . The upper housing  510  may include the support portion  512 . The support portion  512  may be elongated downward from the top end of the upper housing  510 . The support portion  512  may be coupled to the lens barrel  200  and the substrate  600 . For example, the inner surface of the support portion  512  may be coupled to the lens barrel  200 , and the distal end of the support portion  512  may be coupled to the substrate  600 . The support portion  512  and the lens barrel  200  may be fastened to each other by the press-fit, and the support portion  512  and the substrate  600  may be coupled to each other by using the fastening element such as a bolt. 
     The substrate  600  may include an electronic component required to drive the camera module  1003 . For example, the substrate  600  may be equipped with the image sensor  610 , the passive element  620 , and the like. The electronic components mounted on or embedded in the substrate  600  may be electrically connected to each other. For example, the electric circuit electrically connecting the electronic components to each other may be formed on the one surface of or in the substrate  600 . The substrate  600  may provide power and a control signal that are necessary to drive the camera module  1003 . For example, the connection terminal  630  connected to the external power source and the external device may be formed on the rear surface of the substrate  600 . The substrate  600  may be connected to the energy generation unit  400 . For example, the power supply terminal  640  connected to the power terminals  402  and  404  of the energy generation unit  400  may be formed on the one surface of the substrate  600 . The energy generation unit  400  and the power supply terminal  640  may be electrically connected to each other by the power line  642 , the flexible substrate or the like. 
     The cover member  700  may secure the forwardmost lens to the lens barrel  200 . For example, the cover member  700  may be coupled to the lens barrel  200  while pressing the edge of the first lens  110 . The cover member  700  may be adhered or coupled to the lens barrel  200 . As an example, the cover member  700  may be adhered to the lens barrel  200  by the adhesive member. As another example, the cover member  700  may be fastened to the lens barrel  200  by a screw coupling. The former adhering or coupling of the cover member  700  to the lens barrel  200  may improve the airtightness between the cover member  700  and the lens barrel  200 , and the fastening of the cover member  700  to the lens barrel by the screw coupling may increase the adhesion between the first lens  110  and the lens barrel  200  by the cover member  700 . 
     The cover member  700  may be generally made of the material that is the same as or similar to that of the first lens barrel  210 . For example, the cover member  700  may be made of the plastic material. The cover member  700 , being made of the material which is the same as or similar to that of the first lens barrel  210 , may be excellently coupled, adhered, or fastened to the first lens barrel  210 , and may thus significantly reduce the possibility that the forwardmost lens (i.e., first lens  110 ) becomes separated from the lens barrel  200 . However, the cover member  700  is not limited to the plastic material. For example, the cover member  700  may be made of the metal material to protect the first lens  110  from an external impact. 
     The airtight member  800  may be disposed between the first lens  110  and the cover member  700 . For example, the airtight member  800  may be disposed between the step portion  117 , which is formed on the edge of the first lens  110 , and the cover member  700 . The airtight member  800  may be made of the material which may be elastically deformed or compressively deformed. For example, the airtight member  800  may be made of rubber, synthetic rubber, elastomer or the like. However, the airtight member  800  is not limited to the above-mentioned material. The airtight member  800  may block the gap between the first lens  110  and the cover member  700 . For example, the airtight member  800  may be elastically deformed when the cover member  700  and the lens barrel  200  are coupled to each other to block the gap between the first lens  110  and the cover member  700 . 
     The camera module  1003  may remove the foreign matter adhering to the forwardmost lens (i.e., first lens  110 ). For example, the camera module  1003  may remove a raindrop on the first lens  110  in rain, frost or dew occurring on the surface of the first lens  110  due to the difference between day and night temperatures, dust adhering to the surface of the first lens  110 , etc. In addition, the camera module  1003  may improve the heating efficiency of the second lens barrel  220  and first lens  110  by using the insulation member  240 . 
     For example, the first lens  110 , the second lens barrel  220 , and the energy generation unit  400  according to the embodiment of  FIG. 9  may be formed in the shapes shown in  FIGS. 2 through 6B . As an example, the second lens barrel  220  and the energy generation unit  400  shown in  FIG. 9  may be formed in the shapes shown in  FIGS. 2 through 4 . As another example, the first lens  110  and the second lens barrel  220 , shown in  FIG. 9 , may be deformed into the shapes shown in  FIGS. 5A through 6B . As yet another example, the second lens barrel  220  shown in  FIG. 9  may be coupled to the first lens  110  having a shape shown in  FIGS. 5A through 6B  while being coupled to the energy generation unit  400  having a shape shown in  FIGS. 2 through 4 . 
       FIG. 10  illustrates a camera module, according to another embodiment. 
     Referring to  FIG. 10 , a camera module  1004  may include the optical system  100 , the lens barrel  200 , and a heat generation device  410 . 
     The optical system  100  may form the image at a predetermined position by using the light reflected from a subject. For example, the optical system  100  may have the refractive power to form the image at a predetermined position by using the light incident thereon. The optical system  100  may include the plurality of lenses. For example, the optical system  100  may include the five or more lenses including the first to fifth lenses  110 ,  120 ,  130 ,  140  and  150 . However, the number of lenses included in the optical system  100  is not limited to five. For example, the optical system  100  may include four or fewer lenses or include six or more lenses. 
     The forwardmost lens (i.e., first lens  110 ) of the optical system  100 , disposed closest to the object side, may have a diameter larger than that of the other lenses. For example, the first lens  110  may be sized to be in contact with the end of the lens barrel  200 - 1 . Therefore, the first lens  110  may be aligned with the optical axis by the careful adjustment or another process in the state where the first lens  110  is disposed at the end of the lens barrel  200 - 1 . The first lens  110  may be formed for the camera module  1004  to capture the image with a wide angle. As an example, the object-side surface of the first lens  110  may generally have a convex shape. As another example, the first lens  110  may generally have a negative refractive power. 
     The optical system  100  may further include another component in addition to the first to fifth lenses  110  to  150 . For example, the optical system  100  may further include the filter member configured to block infrared light. However, the additional component of the optical system  100  is not limited to the filter member. For example, the optical system  100  may further include a stop disposed between the lens and the lens to control the amount of light, the spacer maintaining a constant distance between the lens and the lens, etc. 
     The optical system  100  may have a predetermined angle of view. For example, the optical system  100  may have an angle of view of 120 degrees or more to simultaneously capture the image over a wide area. However, the angle of view of the optical system  100  is not limited to 120 degrees or more. For example, the optical system  100  may have an angle of view of less than 120 degrees. 
     The lens barrel  200  may accommodate the optical system  100 . For example, the lens barrel  200  may include the accommodation space accommodating the optical system  100 . The lens barrel  200  may accommodate one or more of the first lens  110  to the fifth lens  150  included in the optical system  100 . For example, the lens barrel  200  may accommodate the second to fifth lenses  120  to  150 . 
     The lens barrel  200  may generally have the cylindrical shape. However, the lens barrel  200  is not limited to the cylindrical shape. For example, the lens barrel  200  may have the shape of a quadrangular prism, a rectangular prism, or the like based on a cross-sectional shape of the lenses. 
     There may be the plurality of lens barrels  200 . For example, the lens barrel  200  may include the first lens barrel  210  and the second lens barrel  220 . The first lens barrel  210  and the second lens barrel  220  may be made of materials that are different from each other. As an example, the first lens barrel  210  may be made of the material having low thermal conductivity or the material having low electrical conductivity, and the second lens barrel  220  may be made of the material having high thermal conductivity or the material having high electrical conductivity. As another example, the first lens barrel  210  may be made of the plastic material, and the second lens barrel  220  may be made of the metal material. 
     The first lens barrel  210  may accommodate the optical system  100  and the second lens barrel  220 . For example, the first lens barrel  210  may include the first accommodation portion  212  accommodating the optical system  100  and the second accommodation portion  214  accommodating the second lens barrel  220 . The first accommodation portion  212  and the second accommodation portion  214  may be formed as the spaces independent of each other. For example, the first accommodation portion  212  may be formed in the center of the first lens barrel  210 , and the second accommodation portion  214  may be formed at the predetermined distance outward from the first accommodation portion  212 . The first accommodation portion  212  and the second accommodation portion  214  may each be formed to be elongated in the longitudinal direction of the first lens barrel  210 . The first accommodation portion  212  and the second accommodation portion  214  may be formed to have the sizes or lengths different from each other. For example, the first accommodation portion  212  may be formed to completely penetrate through the first lens barrel  210 , and the second accommodation portion  214  may be formed to have the predetermined length from one end of the first lens barrel  210 . 
     The second lens barrel  220  may be disposed in the second accommodation portion  214  of the first lens barrel  210 . The second lens barrel  220  may be in contact with the first lens  110  which is the forwardmost lens. For example, the one end  221  of the second lens barrel  220  may be in contact with the flange portion  112  of the first lens  110 . 
     The second lens barrel  220  may have the predetermined space in the state of being mounted in the first lens barrel  210 . For example, the concave portion  222  may be formed inside the second lens barrel  220 , and the space of a significant size may be formed between the first lens barrel  210  and the second lens barrel  220 . The concave portion  222  may be elongated upwardly from the distal end of the second lens barrel  220 . 
     The second lens barrel  220  may function as the energy transfer member. In more detail, the second lens barrel  220  may transfer the energy generated by the heat generation device  410  to the adjacent member. As an example, the second lens barrel  220  may be made of the material having high thermal conductivity to easily transfer thermal energy of the heat generation device  410 . The second lens barrel  220  may be made of the metal material described above. However, the material of the second lens barrel  220  is not limited to the metal. For example, the second lens barrel  220  may be made of the material having a high specific heat to maintain the absorbed thermal energy for a long time. 
     The heat generation device  410  may generate the thermal energy. For example, the heat generation device  410  may be the positive temperature coefficient (PTC) heater. The heat generation device  410  may make the camera module  1004  thin. For example, the heat generation device  410  may be the PTC heater in a film shape to minimize the space formed between the first lens barrel  210  and the second lens barrel  220 . 
     The heat generation device  410  may be disposed between the first lens barrel  210  and the second lens barrel  220 . For example, the heat generation device  410  may be disposed in the concave portion  222  of the second lens barrel  220 . The heat generation device  410  may be in close contact with the second lens barrel  220 . For example, the heat generation device  410  may have a shape substantially the same as that of the circular space formed by the concave portion  222  and the second accommodation portion  214 . 
     Most of the thermal energy generated by the heat generation device  410  may be transferred to the second lens barrel  220 . For example, the second lens barrel  220  may be made of the material having a thermal conductivity higher than that of the first lens barrel  210 , and most of the thermal energy generated from the heat generation device  410  may be transferred to the second lens barrel  220 . 
     Referring to  FIGS. 11 and 12 , a second lens barrel  220 - 6  and a heat generation device  410 - 1  may be configured to rapidly heat the second lens barrel  220 - 6  by using the heat generation device  410 - 1 . A deformed shape of the second lens barrel  220 - 6  and the heat generation device  410 - 1  is described below. 
     Referring to  FIGS. 11 and 12 , a plurality of concave portions  222   a  and  222   b  may be formed in a second lens barrel  220 - 6 . For example, the two concave portions  222   a  and  222   b  may be formed in the second lens barrel  220 - 6 . However, the number of the concave portions formed in the second lens barrel  220 - 6  is not limited to two. For example, three or more concave portions may be formed in the second lens barrel  220 - 6 . The concave portions  222   a  and  222   b  may each have a predetermined size. For example, the concave portions  222   a  and  222   b  may have predetermined heights Bh 1  and Bh 2  and widths Bw 1  and Bw 2 . 
     The heat generation device  410 - 1  (including portions  412  and  414 ) may have a thin shape. For example, the heat generation device  410 - 1  may be a positive temperature coefficient (PTC) heater in the shape of a film. The heat generation device  410 - 1  (including  412  and  414 ) may be inserted into the concave portions  222   a  and  222   b  of the second lens barrel  220 - 6 . For example, the heights Hh 1  and Hh 2  and thicknesses Hw 1  and Hw 2  of the heat generation device  410 - 1  (including the portions  412  and  414 ) may each be substantially equal to or less than the heights Bh 1  and Bh 2  and widths Bw 1  and Bw 2  of the concave portions  222   a  and  222   b.    
     The heat generation device  4101 -(including  412  and  414 ) may be generally formed in a rectangular film shape, and may be elastically deformed. Accordingly, the heat generation device  410 - 1  may be elastically deformed and inserted into the circular concave portions  222   a  and  222   b . The heat generation device  410 - 1  may have a predetermined length. For example, the lengths of the heat generation devices  412  and  414  may each be substantially equal to or smaller than arc lengths 2*π*BR 1 , 2*π*BR 2  of the concave portions  222   a  and  222   b . BR 1  and BR 2  may respectively indicate distances (radii) from the concave portions  222   a  and  222   b  to a side closest to the optical axis. 
     The heat generation device  410 - 1  (including  412  and  414 ) according to this embodiment may rapidly heat the second lens barrel  220 - 6 . For example, the thermal energy generated by the heat generation devices  412  and  414  may be transferred to the second lens barrel  220 - 6  through both sides of each of the concave portions  222   a  and  222   b  of the second lens barrel  220 - 6 . Therefore, the second lens barrel  220 - 6  and the heat generation device  410 - 1  may have an increased contact area therebetween, thereby rapidly heating the second lens barrel  220 - 6 . 
     Referring back to  FIG. 10 , the camera module  1004  may further include a component other than the components described above. For example, the camera module  1004  may further include the housing  500 , the substrate  600 , the cover member  700 , etc. 
     The housing  500  may accommodate or support the lens barrel  200  and the substrate  600 . For example, the housing  500  may accommodate the substrate  600  while supporting the lens barrel  200  and the substrate  600 . The housing  500  may include the upper housing  510  and the lower housing  520 . The upper housing  510  may support the lens barrel  200  and the substrate  600 , and the lower housing  520  may seal the open space of the upper housing  510 . The upper housing  510  may include the support portion  512 . The support portion  512  may be elongated downward from the top end of the upper housing  510 . The support portion  512  may be coupled to the lens barrel  200  and the substrate  600 . For example, the inner surface of the support portion  512  may be coupled to the lens barrel  200 , and the distal end of the support portion  512  may be coupled to the substrate  600 . The support portion  512  and the lens barrel  200  may be fastened to each other by the press-fit, and the support portion  512  and the substrate  600  may be coupled to each other by using the fastening element, such as a bolt. 
     The substrate  600  may include an electronic component required to drive the camera module  1004 . For example, the substrate  600  may be equipped with the image sensor  610 , the passive element  620 , and the like. The electronic components mounted on or embedded in the substrate  600  may be electrically connected to each other. For example, the electric circuit electrically connecting the electronic components to each other may be formed on the one surface of or in the substrate  600 . The substrate  600  may provide power and a control signal necessary to drive the camera module  1004 . For example, the connection terminal  630  connected to the external power source and the external device may be formed on the rear surface of the substrate  600 . The substrate  600  may be connected to the heat generation device  410 . For example, the power supply terminal  640  connected to the heat generation device  410  may be formed on the one surface of the substrate  600 . The heat generation device  410  and the power supply terminal  640  may be electrically connected to each other by the power line  642 , the flexible substrate, or the like. 
     The cover member  700  may secure the forwardmost lens to the lens barrel  200 . For example, the cover member  700  may be coupled to the lens barrel  200  while pressing the edge of the first lens  110 . The cover member  700  may be adhered or coupled to the lens barrel  200 . As an example, the cover member  700  may be adhered to the lens barrel  200  by the adhesive member. As another example, the cover member  700  may be fastened to the lens barrel  200  by a screw coupling. The cover member  700  being adhered to the lens barrel  200  by the adhesive member may improve the airtightness between the cover member  700  and the lens barrel  200 , and the cover member  700  being fastened to the lens barrel  200  by the screw coupling may increase the adhesion between the first lens  110  and the lens barrel  200  by the cover member  700 . 
     The cover member  700  may be generally made of a material that is the same as or similar to that of the first lens barrel  210 . For example, the cover member  700  may be made of the plastic material. The cover member  700 , being made of the material that is the same as or similar to that of the first lens barrel  210 , may be excellently coupled, adhered, or fastened to the first lens barrel  210 , and may thus significantly reduce the possibility that the forwardmost lens (i.e., first lens  110 ) becomes separated from the lens barrel  200 . However, the cover member  700  is not limited to the plastic material. For example, the cover member  700  may be made of the metal material to protect the first lens  110  from an external impact. 
     The airtight member  800  may be disposed between the first lens  110  and the cover member  700 . For example, the airtight member  800  may be disposed between the step portion  117 , formed on the edge of the first lens  110 , and the cover member  700 . The airtight member  800  may be made of the material which may be elastically deformed or compressively deformed. For example, the airtight member  800  may be made of rubber, synthetic rubber, elastomer, or the like. However, the airtight member  800  is not limited to the above-mentioned material. The airtight member  800  may block the gap between the first lens  110  and the cover member  700 . For example, the airtight member  800  may be elastically deformed when the cover member  700  and the lens barrel  200  are coupled to each other to block the gap between the first lens  110  and the cover member  700 . 
     The camera module  1004  may remove the foreign matter adhering to the forwardmost lens (i.e., first lens  110 ). For example, the camera module  1004  may use the thermal energy of the heat generating device  410  either to remove a raindrop on the first lens  110  in rain, frost or dew occurring on the surface of the first lens  110  due to a difference between day and night temperatures, or the like, or to block the frost or the dew from occurring therefrom. 
       FIGS. 13 through 14C  illustrate a camera module, according to another embodiment. 
     Referring to  FIGS. 13 through 14C , a camera module  1004   a  may further include the buffer member  230  in addition to the features of the camera module  1004 . 
     The buffer member  230  may be disposed between the first lens barrel  210  and the second lens barrel  220 . For example, the buffer member  230  may be disposed in the concave portion  222  of the second lens barrel  220 . The buffer member  230  may be made of a material which may be elastically deformed or compressively deformed. In addition, the buffer member  230  may be made of a material having strong restoring force. For example, the buffer member  230  may be made of rubber, synthetic rubber, elastomer, or the like. 
     The buffer member  230  may allow the second lens barrel  220  and the heat generation device  410  to be in close contact with each other. As an example, the buffer member  230  may be disposed between the first lens barrel  210  and the heat generation device  410  to provide elastic force for pressing the heat generation device  410  toward the concave portion  222 . As another example, the buffer member  230  may be disposed between the first lens barrel  210  and the second lens barrel  220  to provide elastic force pressing the second lens barrel  220  toward the flange portion  112  of the first lens  110 . 
     The volume of the buffer member  230  may be larger than a volume of a space formed between the lens barrels  210  and  220  and the heat generation device  410  to achieve the above-described effect. For example, as shown in  FIGS. 14A through 14C , the widths Ew 1  and Ew 2  and heights Eh 1  and Eh 2  of the buffer member  230  may be greater than the widths Sw 1  and Sw 2  and heights Sh 1  and Sh 2  of the arrangement space  216  formed between the lens barrels  210  and  220  and the heat generation device  410 . In more detail, the widths Ew 1  and Ew 2  of the buffer member  230  may be greater than the widths Sw 1  and Sw 2  of the arrangement space  216 , and the heights Eh 1  and Eh 2  of the buffer member  230  may be greater than the heights Sh 1  and Sh 2  of the arrangement space  216 . Accordingly, the buffer member  230 , when inserted in the arrangement space  216 , may be compressed or elastically deformed by the deviation between the volume of the buffer member  230  and that of the arrangement space  216 . In addition, the restoring force accumulated by compressing or elastically deforming the buffer member  230  may act as force applied to the heat generation device  410  to cause the heat generation device  410  to be in close contact with the second lens barrel  220  or cause the second lens barrel  220  to be in close contact with the first lens  110 , as shown in  FIG. 14C . Therefore, the camera module  1004   a  may transfer most of the energy generated by the heat generation device  410  to the first lens  110  without loss due to a space between the heat generation device  410  and the second lens barrel  220  or the space between the second lens barrel  220  and the first lens  110 . 
       FIG. 15  illustrates a camera module, according to another embodiment. 
     Referring to  FIG. 15 , a camera module  1004   b  may further include the insulation member  240 . 
     The insulation member  240  may be disposed between the first lens barrel  210  and the second lens barrel  220 . For example, the insulation member  240  may be disposed in the concave portion  222  of the second lens barrel  220 . The insulation member  240  may be made of the material having low thermal conductivity. For example, the insulation member  240  may be made of glass, ceramic, expanded polystyrene, expanded polyurethane, polyethylene, or the like, or may be made of the synthetic material including one or more of the materials described above. 
     The insulation member  240  may improve the heating efficiency of the second lens barrel  220 . For example, the insulation member  240  may block the thermal energy of the heat generation device  410  from being transferred to a member other than the second lens barrel  220 . In order to achieve the above-described effect, the insulation member  240  may enclose every region of the heat generation device  410  that is not in contact with the second lens barrel  220 . 
     Therefore, the camera module  1004   b  may improve the heating efficiency of the second lens barrel  220  by including the insulation member  240 , and may improve the heating rate of the first lens  110  by including the second lens barrel  220 . 
     For reference, the first lens  110  and the second lens barrel  220  may be deformed into the shapes shown in  FIGS. 5A through 6B . For example, the first lens  110  and the second lens barrel  220  shown in  FIGS. 10 and 13 through 14C  may be deformed into the shapes shown in  FIGS. 5A through 6B . 
       FIG. 16  illustrates a camera module, according to another embodiment. 
     Referring to  FIG. 16 , a camera module  1005  may include the optical system  100 , the lens barrel  200 , a barrel holder  300  and the energy generation unit  400 . 
     The optical system  100  may form an image at the predetermined position by using the light reflected from a subject. For example, the optical system  100  may have the refractive power to form the image at a predetermined position by using the light incident thereon. The optical system  100  may include the plurality of lenses. For example, the optical system  100  may include six or more lenses including the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the fifth lens  150 , and a sixth lens  160 . However, the number of lenses included in the optical system  100  is not limited to six. For example, the optical system  100  may include five or fewer lenses or include seven or more lenses. 
     The first to sixth lenses  110 ,  120 ,  130 ,  140 ,  150 , and  160  may be sequentially arranged from the object side. For example, the first lens  110 , the second lens  120 , the third lens  130 , the fourth lens  140 , the fifth lens  150 , and the sixth lens  160  may be sequentially arranged along the optical axis from the object side. The first to sixth lenses  110  to  160  may each be made of a plastic or glass material. For example, the first to sixth lenses  110  to  160  may be all made of the glass material or all made of the plastic material. However, the first to sixth lenses  110  to  160  may not all be made of the same material. For example, at least one of the first to sixth lenses  110  to  160  may be made of the glass material and the rest of the first to sixth lenses  110  to  160  may be made of the plastic material. As an example, the first lens  110  may be made of the glass material. As another specific example, a lens of the optical system  100  having a strong refractive power may be made of the glass material. 
     The optical system  100  may have a predetermined angle of view. For example, the optical system  100  may have an angle of view of 120 degrees or more. However, the angle of view of the optical system  100  is not limited to 120 degrees or more. For example, the optical system  100  may have an angle of view of less than 120 degrees. 
     The optical system  100  may be accommodated in the lens barrel  200 . For example, the first to sixth lenses  110  to  160  may be sequentially accommodated in the lens barrel  200 . However, not all the components of the optical system  100  may be arranged inside the lens barrel  200 . For example, some components of the optical system  100  may be disposed outward from the lens barrel  200 . 
     The optical system  100  may further include a component protecting the first lens  110  from an external impact. For example, the optical system  100  may further include a glass cover panel  102  disposed in front (or on the object side) of the first lens  110 . 
     The glass cover panel  102  may not affect performance of the optical system  100 . For example, the glass cover panel  102  may transfer light incident thereon as it is, without refracting the light. The glass cover panel  102  may be resistant to an external impact. For example, the glass cover panel  102  may be made of a glass material that is resistant to an external impact. However, the material of the glass cover panel  102  is not limited to the glass. For example, the glass cover panel  102  may be made of the plastic material having sufficient strength. The glass cover panel  102  may be coupled to the barrel holder  300 . For example, an edge of the glass cover panel  102  may be in contact with or coupled to one end of the barrel holder  300 . The glass cover panel  102  may be convex to the object side. For example, a curvature radius Gr of an inner surface of the glass cover panel  102  may be substantially equal to or greater than a curvature radius LR 1  of the object-side surface of the first lens  110 . However, the glass cover panel  102  may not be necessarily convex. For example, the glass cover panel  102  may be flat as shown in  FIG. 20 . A predetermined space ES 1  may be formed between an inner surface GS 2  of the glass cover panel  102  and the object-side surface L 1 S 1  of the first lens  110 . The space ES 1  may prevent the inner surface GS 2  of the glass cover panel  102  and the object-side surface L 1 S 1  of the first lens  110  from being in direct contact with each other. In addition, the space ES 1  may reduce or block the external heat or cold air of the glass cover panel  102  from being transferred to the first lens  110 . Therefore, the camera module  1005  may minimize change in an optical feature (e.g., refractive index) of the optical system  100 , due to change in a temperature of the external environment. 
     The optical system  100  may further include the filter member configured to block the infrared light. In addition, the optical system  100  may further include the stop disposed between the lens and the lens to control the amount of light, the spacer maintaining a constant distance between the lens and the lens, etc. However, the optical system  100  may not necessarily include the filter member, the spacer, the stop and the like, described above. As an example, the optical system  100  may omit the filter member. 
     The lens barrel  200  may accommodate the optical system  100 . For example, the lens barrel  200  may include the accommodation space accommodating the optical system  100 . The lens barrel  200  may accommodate one or more of the first lens  110  to the sixth lens  160  included in the optical system  100 . For example, the lens barrel  200  may accommodate all of the first lens  110  to the sixth lens  160 . The lens barrel  200  may generally have the cylindrical shape. However, the lens barrel  200  is not limited to the cylindrical shape. For example, the lens barrel  200  may have the shape of a quadrangular prism, a rectangular prism, or the like based on a cross-sectional shape of the lenses. 
     For example, the barrel holder  300  may accommodate the lens barrel  200 . The barrel holder  300  may secure the lens barrel  200  to the housing  500 . For example, the barrel holder  300  may be firmly coupled to the housing  500  while accommodating the lens barrel  200 . 
     The barrel holder  300  may include a plurality of members. For example, the barrel holder  300  may include a first barrel holder  310  and a second barrel holder  320 . The first barrel holder  310  and the second barrel holder  320  may be made of materials different from each other. As an example, the first barrel holder  310  may be made of the material having low thermal conductivity or the material having low electrical conductivity, and the second barrel holder  320  may be made of the material having high thermal conductivity or the material having high electrical conductivity. As another example, the first barrel holder  310  may be made of the plastic material, and the second barrel holder  320  may be made of the metal material. 
     The first barrel holder  310  may accommodate the lens barrel  200  and the second barrel holder  320 . For example, the first barrel holder  310  may include a first accommodation portion  312  accommodating the lens barrel  200  and a second accommodation portion  314  accommodating the second barrel holder  320 . The first accommodation portion  312  and the second accommodation portion  314  may be formed as the spaces independent of each other. For example, the first accommodation portion  312  may be formed in a center of the first barrel holder  310 , and the second accommodation portion  314  may be formed along an edge of the first barrel holder  310  at a predetermined distance from the first accommodation portion  312 . The first accommodation portion  312  and the second accommodation portion  314  may each be formed to be elongated in the longitudinal direction of the first barrel holder  310 . The first accommodation portion  312  and the second accommodation portion  314  may be formed to have sizes or lengths that are different from each other. For example, the first accommodation portion  312  may be formed to completely penetrate through the first barrel holder  310 , and the second accommodation portion  314  may be formed to have a predetermined length from one end of the first barrel holder  310 . 
     The second barrel holder  320  may be disposed in the second accommodation portion  314  of the first barrel holder  310 . The second barrel holder  320  may be in contact with the glass cover panel  102 . For example, the second barrel holder  320  may be in contact with the edge of the glass cover panel  102  while being mounted in the second accommodation portion  314  of the first barrel holder  310 . 
     A predetermined space may be formed between the first barrel holder  310  and the second barrel holder  320 . For example, a concave portion  322  may be formed inside the second barrel holder  320 , and a space of a significant size may be formed between the first barrel holder  310  and the second barrel holder  320 . The concave portion  322  may be elongated upwardly from a distal end of the second barrel holder  320 . 
     The second barrel holder  320  may function as the energy transfer member. In more detail, the second barrel holder  320  may transfer the energy generated from the energy generation unit  400 . As an example, the second barrel holder  320  may be made of a material having high thermal conductivity to easily transfer the thermal energy of the energy generation unit  400 . As another example, the second barrel holder  320  may be made of a material having a high vibration frequency to easily transfer the vibration energy of the energy generation unit  400 . The second barrel holder  320  may be made of the metal material to easily transfer the thermal energy or the vibration energy. However, the material of the second barrel holder  320  is not limited to the metal. For example, the second barrel holder  320  may be made of the material having a high specific heat to maintain the absorbed thermal energy for a long time. 
     The energy generation unit  400  may generate the predetermined amount of energy. For example, the energy generation unit  400  may be the heat generation device configured to generate thermal energy. As an example, the energy generation unit  400  may be the positive temperature coefficient (PTC) heater. However, the energy generation unit  400  is not limited to the heat generation device. For example, the energy generation unit  400  may be the excitation device or piezoelectric body configured to generate vibration energy. 
     The energy generation unit  400  may be disposed between the first barrel holder  310  and the second barrel holder  320 . For example, the energy generation unit  400  may be disposed in the concave portion  322  of the second barrel holder  320 . The energy generation unit  400  may be in close contact with the second barrel holder  320 . For example, the energy generation unit  400  may have a shape substantially the same as that of a circular space formed by the concave portion  322  and the second accommodation portion  314 . However, the energy generation unit  400  is not limited to the shape of the space formed by the concave portion  322  and the second accommodation portion  314 . 
     The energy generation unit  400  may transfer energy to the second barrel holder  320 . For example, the energy generation unit  400  may be in contact with the concave portion  322  of the second barrel holder  320  to transfer the thermal energy, the vibration energy, and the like, generated by the energy generation unit  400 , to the second barrel holder  320 . The energy generated by the energy generation unit  400  may be transferred effectively to the second barrel holder  320  than to the first barrel holder  310 . For example, the second barrel holder  320  may be made of a material which may receive the thermal energy, the vibration energy, and the like more easily than that of the first barrel holder  310 , and most of the energy generated from the energy generation unit  400  may thus be transferred to the second barrel holder  320  or absorbed into the second barrel holder  320 . 
     The camera module  1005  may further include a component other than the components described above. For example, the camera module  1005  may further include the housing  500 , the substrate  600 , the cover member  700 , etc. 
     The housing  500  may accommodate or support the first barrel holder  310  and the substrate  600 . For example, the housing  500  may accommodate the substrate  600  while supporting the first barrel holder  310  and the substrate  600 . The housing  500  may include the upper housing  510  and the lower housing  520 . The upper housing  510  may support the first barrel holder  310  and the substrate  600 , and the lower housing  520  may seal the open space of the upper housing  510 . The upper housing  510  may include the support portion  512 . The support portion  512  may be elongated downward from the top end of the upper housing  510 . The support portion  512  may be coupled to the first barrel holder  310  and the substrate  600 . For example, the inner surface of the support portion  512  may be coupled to the first barrel holder  310 , and the distal end of the support portion  512  may be coupled to the substrate  600 . The support portion  512  and the first barrel holder  310  may be fastened to each other by the press-fit, and the support portion  512  and the substrate  600  may be coupled to each other by using the fastening element such as a bolt. 
     The substrate  600  may include an electronic component required to drive the camera module  1005 . For example, the substrate  600  may be equipped with the image sensor  610 , the passive element  620  and the like. The electronic components mounted on or embedded in the substrate  600  may be electrically connected to each other. For example, the electric circuit electrically connecting the electronic components to each other may be formed on the one surface of or in the substrate  600 . The substrate  600  may provide power and a control signal necessary to drive the camera module  1005 . For example, the connection terminal  630 , which is connected to the external power source and the external device, may be formed on the rear surface of the substrate  600 . The substrate  600  may be connected to the energy generation unit  400 . For example, the power supply terminal  640  connected to the power terminals  402  and  404  of the energy generation unit  400  may be formed on the one surface of the substrate  600 . The energy generation unit  400  and the power supply terminal  640  may be electrically connected to each other by the power line  642 , the flexible substrate or the like. 
     The cover member  700  may secure the glass cover panel  102  to the barrel holder  300 . For example, the cover member  700  may be coupled to the barrel holder  300  while pressing the edge of the glass cover panel  102 . The cover member  700  may be adhered or coupled to the barrel holder  300 . As an example, the cover member  700  may be adhered to the barrel holder  300  by the adhesive member. As another example, the cover member  700  may be fastened to the barrel holder  300  by screw coupling. The cover member  700  being adhered or coupled to the barrel holder  300  may improve airtightness between the cover member  700  and the barrel holder  300 , and the cover member  700  being fastened to the barrel holder  300  by screw coupling may increase adhesion between the glass cover panel  102  and the barrel holder  300  by the cover member  700 . 
     The cover member  700  may be generally made of a material which is the same as or similar to that of the first barrel holder  310 . For example, the cover member  700  may be made of the plastic material. The cover member  700 , when made of the material that is the same as or similar to that of the first barrel holder  310 , may be excellently coupled, adhered, or fastened to the first barrel holder  310 , and may thus significantly reduce a possibility that the glass cover panel  102  becomes separated from the first barrel holder  310 . However, the cover member  700  is not limited to the plastic material. 
     The airtight member  800  may be disposed between the glass cover panel  102  and the first barrel holder  310 . The airtight member  800  may be made of the material which may be elastically deformed or compressively deformed. For example, the airtight member  800  may be made of rubber, synthetic rubber, elastomer or the like. However, the airtight member  800  is not limited to the above-mentioned material. The airtight member  800  may block a gap between the glass cover panel  102  and the first barrel holder  310 . For example, the airtight member  800  may be elastically deformed when the cover member  700  and the first barrel holder  310  are coupled to each other to block the gap between the glass cover panel  102  and the first barrel holder  310 . 
     The camera module  1005  may remove the foreign matter adhering to the glass cover panel  102 . For example, the camera module  1005  may remove frost, moisture, dew, a raindrop, or the like adhering to a surface of the glass cover panel  102  by using vibration, heat, static electricity, etc. 
       FIGS. 17 through 19  illustrate modified examples in which a second barrel holder and an energy generation unit are coupled to each other for effectively transferring the energy of the energy generation unit, according to an embodiment. 
     The second barrel holder and the energy generation unit may be formed to increase energy transfer efficiency. For example, the second barrel holder and the energy generation unit may have an increased area in which the second barrel holder and the energy generation unit are in contact with or face each other. 
     Referring to  FIG. 17 , as an example, a second barrel holder  320 - 1  and the energy generation unit  400 - 1  may have a plurality of steps  326  and  416 , respectively. Referring to  FIG. 18 , as another example, a second barrel holder  320 - 2  and the energy generation unit  400 - 2  may have a plurality of grooves  327  and protrusions  417 , respectively. Referring to  FIG. 19 , as another example, a second barrel holder  320 - 3  may have the steps  326  and the grooves  327  and the energy generation unit  400 - 3  may have the steps  416  and the protrusions  417 . 
     Referring to  FIG. 17 , the second barrel holder  320 - 1  and the energy generation unit  400 - 1  may each have a step difference. For example, the second barrel holder  320 - 1  may have the plurality of steps  326  formed in an inner circumferential surface  325 , and the energy generation unit  400 - 1  may have the plurality steps  416  formed on the outer circumferential surface  415 . The inner circumferential surfaces  325  and steps  326  of the second barrel holder  320 - 1  may generally be in contact with the outer circumferential surfaces  415  and steps  416  of the energy generation unit  400 - 1 . As an example, the inner circumferential surfaces  325  of the second barrel holder  320 - 1  may be in contact with the outer circumferential surfaces  415  of the energy generation unit  400 - 1 , and the steps  326  of the second barrel holder  320 - 1  may be in contact with the steps  416  of the energy generation unit  400 - 1 . As another example, the inner circumferential surface  325  of the second barrel holder  320 - 1  may have substantially the same size (or diameter) as the outer circumferential surface  415  of the energy generation unit  400 - 1 , and the step  326  of the second barrel holder  320 - 1  may have substantially the same size as the step  416  of the energy generation unit  400 - 1 . 
     The second barrel holder  320 - 1  may have a cross-sectional area which is increased in the upward direction (i.e., toward the glass cover panel  102 ). For example, thicknesses BHT 1 , BHT 2 , BHT 3  and BHT 4  of the second barrel holder  320 - 1  may be increased in the upward direction. The energy generation unit  400 - 1  may have the cross-sectional area which is decreased in the upward direction. For example, the thicknesses WH 1 , WH 2  and WH 3  of the energy generation unit  400 - 1  may be decreased in the upward direction. 
     The second barrel holder  320 - 1  and the energy generation unit  400 - 1  may easily transfer energy upward. For example, the second barrel holder  320 - 1  may have the cross-sectional area that is increased in the upward direction, and the lower the portion of the second barrel holder  320 - 1 , the faster the energy of the energy generation unit  400  may be absorbed or transferred. In contrast, the energy generation unit  400 - 1  may have the cross-sectional area that is increased in the downward direction, and the lower the portion of the energy generation unit  400 - 1 , the greater the energy that may be generated. 
     In consideration of the description above, the energy generated from the energy generation unit  400 - 1  not only be rapidly transferred but also be increased, toward the lower portion of the second barrel holder  320 - 1 . Meanwhile, the energy has a tendency to be moved from a place having a high displacement to a place having a low displacement, and the energy transferred to the second barrel holder  320 - 1  may thus be moved from its lower portion to its upper portion. Therefore, according to the second barrel holder  320 - 1  and the energy generation unit  400 - 1 , the energy of the energy generation unit  400 - 1  may be rapidly transferred or supplied to the glass cover panel  102  positioned at a forwardmost of camera module  1005 . 
     Referring to  FIG. 18 , the second barrel holder  320 - 2  and the energy generation unit  400 - 2  may have the grooves  327  and the protrusions  417 , respectively. For example, the second barrel holder  320 - 2  may have the plurality of grooves  327  formed in the inner circumferential surface  325 , and the energy generation unit  400 - 2  may have the plurality of protrusions  417  formed on the outer circumferential surface  415 . The second barrel holder  320 - 2  may generally be mesh-coupled to the energy generation unit  400 - 2 . As an example, the inner circumferential surfaces  325  of the second barrel holder  320 - 2  may be in contact with the outer circumferential surfaces  415  of the energy generation unit  400 - 2 , and the grooves  327  of the second barrel holder  320 - 2  may be in mesh contact with the protrusions  417  of the energy generation unit  400 - 2   
     The second barrel holder  320 - 2  and the energy generation unit  400 - 2  may have an increased area in which the second barrel holder  320 - 2  and the energy generation unit  400 - 2  are in contact with or face each other by the grooves  327  and the protrusions  417 , thus improving the energy transfer efficiency through the conduction or the convection. 
     Referring to  FIG. 19 , the second barrel holder  320 - 3  and the energy generation unit  400 - 3  may include all the features shown in  FIGS. 17 and 18 . For example, the second barrel holder  320 - 3  may have the steps  326  and the grooves  327 , and the energy generation unit  400 - 3  may have the steps  416  and the protrusions  417 . Therefore, the second barrel holder  320 - 3  and the energy generation unit  400 - 3  may have all the advantages of the barrel holder  320 - 1  and the energy generation unit  400 - 1  shown in  FIG. 17 , and the barrel holder  320 - 2  and the energy generation unit  400 - 2  shown in  FIG. 18 . 
     Referring to  FIGS. 21A through 22B , a second barrel holder and an energy generation unit may be in close contact with each other. For example, a groove accommodating an energy generation unit may be formed in the second barrel holder and the energy generation unit may have a shape allowing the groove of the second barrel holder to be inserted thereinto. 
     Referring to  FIGS. 21A and 21B , an energy generation unit  410 - 2  may be a heat generation device. For example, the energy generation unit  410 - 2  may be a heat generation device of a film shape. The heat generation device  410 - 2  may prevent overheating of a heating object. For example, the heat generation device  410 - 2  may be a positive temperature coefficient (PTC) heater that is always maintained at a constant temperature. However, the heat generation device  410 - 2  is not limited to the PTC heater. The heat generation device  410 - 2  may be coupled to the groove  324  of a second barrel holder  320 - 4 . For example, the heat generation device  410 - 2  may have the shape of a film which may be easily deformed, and may be inserted into the groove  324  of the second barrel holder  320 - 4 . The heat generation device  410 - 2  may heat the second barrel holder  320 - 4 . For example, the heat generation device  410 - 2  may dissipate heat while being mounted in the groove  324  to heat the second barrel holder  320 - 4 . 
     The number of the grooves and the number of heat generation devices formed in the second barrel holder may be increased or decreased as needed. For example, as shown in  FIGS. 22A and 22B , three grooves  324   a ,  324   b  and  324   c  may be formed in a second barrel holder  320 - 5 . In addition, the same number of heat generation devices  410 - 2   a ,  410 - 2   b  and  410 - 2   c  may be formed in the grooves  324   a ,  324   b  and  324   c.    
     In the modified examples of  FIGS. 21A to 22B  described above, the second barrel holder and the heat generation device(s) may not only be easily coupled to each other, but also have an increased area in which the second barrel holder and the heat generation device(s) transfer heat to each other, thereby rapidly heating the second barrel holder by using the heat generation device(s). 
       FIG. 23  illustrates a camera module, according to another embodiment. 
     Referring to  FIG. 23 , a camera module  1006  may include the optical system  100 , a lens barrel  200 - 6 , a barrel holder  300 - 6 , and an energy generation unit  400 - 6 . 
     The optical system  100  may form an image at a predetermined position by using the light reflected from a subject. For example, the optical system  100  may have the refractive power to form the image at the predetermined position by using the light incident thereon. The optical system  100  may include the five or more lenses, including the first to fifth lenses  110 ,  120 ,  130 ,  140 , and  150 . However, the number of lenses included in the optical system  100  is not limited to five. For example, the optical system  100  may include four or fewer lenses or include six or more lenses. 
     The front lens (i.e., first lens  110 ) of the optical system  100 , which is disposed closest to the object side, may have a larger diameter than the other lenses. For example, the first lens  110  may be sized to be in contact with the end of the lens barrel  200 - 6 . Therefore, the first lens  110  may be aligned with the optical axis by the careful adjustment or another process in the state where the first lens  110  is disposed at the end of the lens barrel  200 - 6 . 
     The optical system  100  may further include another component in addition to the first to fifth lenses  110 ,  120 ,  130 ,  140 , and  150 . For example, the optical system  100  may further include a filter member configured to block infrared light. However, the additional component of the optical system  100  is not limited to the filter member. For example, the optical system  100  may further include a stop disposed between the lens and the lens to control the amount of light, the spacer maintaining a constant distance between the lens and the lens, etc. However, the optical system  100  may not necessarily include the filter member, the stop, the spacer, and the like. For example, the optical system  100  may optionally omit the filter member, the stop, or the spacer. The optical system  100  may be formed for the camera module  1006  to capture the image with a wide angle. For example, the first lens  110  may have the convex object-side surface and the negative refractive power. 
     The lens barrel  200 - 6  may accommodate the optical system  100 . For example, the lens barrel  200  may include an accommodation space  202  accommodating the optical system  100 . The lens barrel  200 - 6  may accommodate one or more of the first to fifth lenses  110  to  150  included in the optical system  100 . For example, the lens barrel  200 - 6  may accommodate the second to fifth lenses  120  to  150 . The lens barrel  200 - 6  may generally have the cylindrical shape. However, the lens barrel  200 - 6  is not limited to the cylindrical shape. For example, the lens barrel  200 - 6  may have the shape of a quadrangular prism, a rectangular prism, or the like based on a cross-sectional shape of the lenses. 
     The lens barrel  200 - 6  may accommodate the energy generation unit  400 - 6 . For example, a seating portion  204  accommodating the energy generation unit  400 - 6  may be formed on one side of the lens barrel  200 - 6 . The seating portion  204  may have a predetermined depth from a top portion of the lens barrel  200 - 6 . In addition, the seating portion  204  may be open toward the accommodation space  202  of the lens barrel  200 - 6 . Accordingly, a member disposed on the seating portion  204  may be in contact with both the first lens  110  disposed on the top portion of the lens barrel  200 - 6  and the second lens  120  disposed in the accommodation space  202 . 
     The lens barrel - 6  may absorb the deformation of the optical system  100  caused by a temperature change. For example, the lens barrel  200 - 6  may be made of a material having a thermal expansion coefficient similar to that of the optical system  100 . For example, the lens barrel  200 - 6  may be made of a plastic material. However, the lens barrel  200  is not limited to the plastic material. 
     The barrel holder  300 - 6  may be coupled to the lens barrel  200 - 6 . For example, the barrel holder  300 - 6  may be coupled with the lens barrel  200 - 6  by screw a coupling, a press-fit, etc. The barrel holder  300 - 6  may be coupled with the substrate  600 . For example, the barrel holder  300 - 6  may be coupled with the substrate  600  by a fastening element such as a bolt, a screw, or the like. 
     The barrel holder  300 - 6  may maintain a constant back focal length (BFL, that is, a distance from a rearmost lens to a top surface of the image sensor  610 ) of the optical system  100 . As an example, the barrel holder  300 - 6  may maintain the constant back focal length (BFL) of the optical system  100  by adjusting the amount of force applied to fasten the barrel holder  300 - 6  and the lens barrel  200 - 6  to each other. 
     The barrel holder  300 - 6  may minimize an amount of change in the back focal length (BFL) based on the temperature change. For example, the barrel holder  300 - 6  may be made of a material having a thermal expansion coefficient substantially the same as or similar to the amount of change in the back focal length (BFL) based on the temperature change. For example, the barrel holder  300 - 6  may be made of the plastic material which may be easily stretched and contracted based on the temperature change. However, the barrel holder  300 - 6  is not limited to the plastic material. 
     The energy generation unit  400 - 6  may generate a predetermined amount of energy. For example, the energy generation unit  400 - 6  may be a heat generation device configured to generate the thermal energy. As a specific example, the energy generation unit  400 - 6  may be the positive temperature coefficient (PTC) heater. However, the energy generation unit  400 - 6  is not limited to the heat generation device. For example, the energy generation unit  400 - 6  may be an excitation device or a piezoelectric body configured to generate vibration energy. 
     The energy generation unit  400 - 6  may be disposed in the seating portion  204  of the lens barrel  200 - 6 . The energy generation unit  400 - 6  may have a size substantially the same as or similar to a volume of the seating portion  204 . For example, the energy generation unit  400  may have the same disc shape as the seating portion  204 . However, the energy generation unit  400 - 6  is not limited to the disc shape. 
     The energy generation unit  400 - 6  may provide energy to the forwardmost lens. For example, the energy generation unit  400 - 6  may supply the energy to the first lens  110  positioned at the forwardmost of the optical system  100 . The energy generation unit  400 - 6  may be in direct or indirect contact with the first lens  110  to supply the energy to the first lens  110 . For example, the energy generation unit  400 - 6  may be in contact with the flange portion  112  of the first lens  110 , and transfer the energy through the flange portion  112 . 
     The energy generation unit  400 - 6  may remove the foreign matter adhering to the forwardmost lens. As an example, the energy generation unit  400  may remove frost, moisture and water droplet, adhering to the surface of the first lens  110  by heating the first lens  110 . As another example, the energy generation unit  400  may vibrate the first lens  110  to remove the foreign matter such as dust or the like, adhering to the surface of the first lens  110 . 
     The energy generation unit  400 - 6  may provide the energy to the plurality of lenses. For example, the energy generation unit  400  may provide the energy to the second lens  120  in addition to the first lens  110 . For example, the energy generation unit  400 - 6  may be in contact with the second lens  120  disposed in the accommodation space  202 , and may transfer the thermal energy and the vibration energy to the second lens  120  as well. 
     The energy generation unit  400 - 6  may serve to maintain a constant performance of the optical system  100 . For example, the energy generation unit  400  may maintain the first lens  110  and the second lens  120  at the constant temperature, and may thus reduce a possibility that the refractive indices of the first lens  110  and second lens  120  are changed by the external temperature change. 
     Therefore, the camera module  1006  may remove the foreign matter adhering to the forwardmost lens by using the energy generation unit  400 - 6 , and may simultaneously maintain the constant performance of the optical system  100 . 
     The camera module  1006  may further include a component other than the components described above. For example, the camera module  1006  may further include the housing  500 , the substrate  600 , the cover member  700 , etc. 
     The housing  500  may accommodate or support the lens barrel  200 - 6  and the substrate  600 . For example, the housing  500  may accommodate the substrate  600  while supporting the lens barrel  200 - 6  and the substrate  600 . 
     The substrate  600  may include an electronic component required to drive the camera module  1006 . For example, the substrate  600  may be equipped with the image sensor  610 , the passive element  620 , and the like. The electronic components mounted on or embedded in the substrate  600  may be electrically connected to each other. For example, the electric circuit electrically connecting the electronic components to each other may be formed on the one surface of or in the substrate  600 . The substrate  600  may provide power and a control signal, necessary to drive the camera module  1006 . For example, the connection terminal  630 , which is connected to the external power source and the external device, may be formed on the rear surface of the substrate  600 . The substrate  600  may be connected to the energy generation unit  400 - 6 . For example, the power supply terminal  640  connected to a power terminal of the energy generation unit  400 - 6  may be formed on the one surface of the substrate  600 . The energy generation unit  400 - 6  and the power supply terminal  640  may be electrically connected to each other by the power line  642 , the flexible substrate, or the like. 
     The cover member  700  may secure the forwardmost lens to the lens barrel  200 - 6 . For example, the cover member  700  may be coupled to the lens barrel  200 - 6  while pressing the edge of the first lens  110 . The cover member  700  may be adhered or coupled to the lens barrel  200 - 6 . As an example, the cover member  700  may be adhered to the lens barrel  200 - 6  by the adhesive member. As another example, the cover member  700  may be fastened to the lens barrel  200 - 6  by a screw coupling. The cover member  700  being adhered to the lens barrel  200 - 6  by the adhesive member may improve the airtightness between the cover member  700  and the lens barrel  200 - 6 , and the cover member  700  being fastened to the lens barrel  200 - 6  by the screw coupling may increase the adhesion between the first lens  110  and the lens barrel  200 - 6  by the cover member  700 . 
     The cover member  700  may be generally made of a material which is the same as or similar to that of the lens barrel  200 - 6 . For example, the cover member  700  may be made of the plastic material. The cover member  700 , made of the material which is the same as or similar to that of the lens barrel  200 - 6 , may be excellently coupled, adhered or fastened to the lens barrel  200 - 6 , and may thus significantly reduce the possibility that the front lens (i.e., first lens  110 ) is separated from the lens barrel  200 - 6 . However, the cover member  700  is not limited to the plastic material. For example, the cover member  700  may be made of the metal material to protect the first lens  110  from an external impact. 
     The airtight member  800  may be disposed between the first lens  110  and the cover member  700 . For example, the airtight member  800  may be disposed between the step portion  117 , formed on the edge of the first lens  110 , and the cover member  700 . The airtight member  800  may be made of the material which may be elastically deformed or compressively deformed. For example, the airtight member  800  may be made of rubber, synthetic rubber, elastomer, or the like. However, the airtight member  800  is not limited to the above-mentioned material. The airtight member  800  may block the gap between the first lens  110  and the cover member  700 . For example, the airtight member  800  may be elastically deformed when the cover member  700  and the lens barrel  200  are coupled to each other to block the gap between the first lens  110  and the cover member  700 . 
       FIG. 24  illustrates a camera module, according to another embodiment. 
     Referring to  FIG. 24 , a camera module  1006   a  may include the elements of the camera module  1006  of  FIG. 23 , and may further include a component that may allow the first lens  110  and the energy generation unit  400 - 6  to be in close contact with each other, or a component that may minimize energy loss occurring between the first lens  110  and the energy generation unit  400 - 6 . For example, the camera module  1006   a  may further include a buffer member  230 - 1  or an insulation member  240 - 1 . 
     In an example in which the camera module  1006   a  includes the buffer member  230 - 1 , the buffer member  230 - 1  may be disposed in the seating portion  204  of the lens barrel  200 - 6 . For example, the buffer member  230 - 1  may be disposed between the seating portion  204  and the energy generation unit  400 - 6 . The buffer member  230 - 1  may be made of a material that may be elastically deformed or compressively deformed. In addition, the buffer member  230 - 1  may be made of a material having strong restoring force. For example, the buffer member  230 - 1  may be made of rubber, synthetic rubber, elastomer, or the like. 
     The buffer member  230 - 1  may allow the first lens  110  and the energy generation unit  400 - 6  to be in close contact with each other. For example, the buffer member  230 - 1  may press the energy generation unit  400 - 6  upward for the energy generation unit  400 - 6  to be in close contact with the flange portion  112  of the first lens  110 . 
     In an example in which the camera module  1006   a  includes the insulation member  240 - 1 , the insulation member  240 - 1  may be disposed in the seating portion  204  of the lens barrel  200 - 6 . For example, the insulation member  240 - 1  may be disposed between the seating portion  204  and the energy generation unit  400 - 6 . The insulation member  240 - 1  may minimize energy loss. As an example, the insulation member  240 - 1  may surround an outer surface of the energy generation unit  400 - 6  except for a portion where the energy generation unit  400  and the first lens  110  are in contact with each other. As another example, the insulation member  240  may surround the outer surface of the energy generation unit - 6  except for the portion where the energy generation unit  400 - 6  and the first lens  110  are in contact with each other and a portion where the energy generation unit  400 - 6  and the second lens  120  are in contact with each other. 
     The insulation member  240 - 1  may be made of a material having low thermal conductivity or a material having low energy transfer rate. For example, the insulation member  240 - 1  may be made of glass, ceramic, expanded polystyrene, expanded polyurethane, polyethylene, or the like, or may be made of the synthetic material including one or more of the materials described above. However, the insulation member  240 - 1  is not limited to the above-mentioned materials. 
     In the camera module  1006   a  including the insulation member  240 - 1 , most of the energy generated by the energy generation unit  400 - 6  may be transferred only to the first lens  110  or the first lens  110  and the second lens  120 , and may thus have improved efficiency of removing the foreign matter by using the energy generation unit  400 - 6 . 
       FIG. 25  illustrates a camera module, according to another embodiment. 
     Referring to  FIG. 25 , a camera module  1007  may include the optical system  100 , a lens barrel  200 - 7 , a barrel holder  300 - 7  and an energy generation unit  400 - 7 . 
     The optical system  100  may form an image at a predetermined position by using the light reflected from a subject. For example, the optical system  100  may have a refractive power to form the image at the predetermined position by using the light incident thereon. The optical system  100  may include the five or more lenses including the first to fifth lenses  110 ,  120 ,  130 ,  140  and  150 . However, the number of lenses included in the optical system  100  is not limited to five. For example, the optical system  100  may include four or fewer lenses or include six or more lenses. 
     The forwardmost lens (i.e., first lens  110 ) of the optical system  100 , which is disposed closest to the object side, may have a diameter larger than that of the other lenses. For example, the first lens  110  may be sized to be in contact with the end of the lens barrel  200 - 7 . Therefore, the first lens  110  may be aligned with the optical axis by the careful adjustment or another process in the state where the first lens  110  is disposed at the end of the lens barrel  200 - 7 . 
     The lens barrel  200 - 7  may accommodate the optical system  100 . For example, the lens barrel  200 - 7  may include the accommodation space  202  accommodating the optical system  100 . The lens barrel  200  may accommodate one or more of the second to fifth lenses  120  to  150  included in the optical system  100 . The lens barrel  200 - 7  may be made of a material which may easily transfer energy. For example, the lens barrel  200 - 7  may be made of a metal material. However, the lens barrel - 7  is not limited to the metal material. 
     The lens barrel  200 - 7  may be in contact with the flange portion  112  of the first lens  110 . For example, the lens barrel  200 - 7  may include a flange portion  206  in contact with the flange portion  112  of the first lens  110 . The flange portion  206  of the lens barrel  200  may have substantially the same size as the flange portion  112  of the first lens  110 . The flange portion  206  of the lens barrel  200 - 7  may not necessarily have the same size as the flange portion  112  of the first lens  110 . For example, the flange portion  206  of the lens barrel  200 - 7  may have a larger size or a smaller size than the flange portion  112  of the first lens  110 . 
     The barrel holder  300 - 7  may be coupled to the lens barrel  200 - 7 . For example, the barrel holder  300 - 7  may be coupled with the lens barrel  200 - 7  by a screw coupling, a press-fit, etc. The barrel holder  300 - 7  may include a space in which the flange portion  206  of the lens barrel  200 - 7  and the energy generation unit  400 - 7  are disposed. For example, a seating portion  304  may be formed in the barrel holder  300 - 7 . The seating portion  304  may be sized to accommodate the flange portion  206  of the lens barrel  200 - 7 . For example, the seating portion  304  may have substantially the same size as the flange portion  206 . 
     The energy generation unit  400 - 7  may generate a predetermined amount of energy. For example, the energy generation unit  400 - 7  may be a heat generation device configured to generate thermal energy. As a specific example, the energy generation unit  400 - 7  may be a positive temperature coefficient (PTC) heater. However, the energy generation unit  400 - 7  is not limited to the heat generation device. For example, the energy generation unit  400 - 7  may be an excitation device or a piezoelectric body configured to generate vibration energy. 
     The energy generation unit  400 - 7  may be disposed in the seating portion  304  of the barrel holder  300 - 7 . In more detail, the energy generation unit  400 - 7  may be disposed between the seating portion  304  and the flange portion  206 . The energy generation unit  400 - 7  may substantially have a disc shape. However, the energy generation unit  400 - 7  is not limited to the disc shape. 
     The energy generation unit  400 - 7  may provide energy to the forwardmost lens. For example, the energy generation unit  400 - 7  may supply the energy to the first lens  110  positioned at the forwardmost of the optical system  100 . The energy generation unit  400 - 7  may be in indirect contact with the first lens  110  to supply the energy to the first lens  110 . For example, the energy generation unit  400 - 7  may transfer the energy to the first lens  110  through the lens barrel  200 - 7 . 
     The energy generation unit  400 - 7  may remove foreign matter adhering to the forwardmost lens. As an example, the energy generation unit  400 - 7  may remove frost, moisture and water droplets adhering to the surface of the first lens  110  by providing the thermal energy to the first lens  110 . As another example, the energy generation unit  400 - 7  may provide the vibration energy to the first lens  110  to remove the foreign matter such as dust, adhering to the surface of the first lens  110 . 
     The energy generation unit  400 - 7  may provide the energy to the plurality of lenses. For example, the energy generation unit  400 - 7  may provide the energy to the second to fifth lenses  120  to  150  through the lens barrel  200 - 7 . In more detail, the energy generation unit  400 - 7  may directly heat the lens barrel  200 - 7  to indirectly heat the second to fifth lenses  120  to  150 . 
     The energy generation unit  400 - 7  may function to maintain the constant performance of the optical system  100 . For example, the energy generation unit  400 - 7  may heat the lens barrel  200 - 7  and thus maintain the constant temperature of the second to fifth lenses  120  to  150 , as described above. Therefore, the camera module  1007  may remove foreign matter adhering to the forwardmost lens by using the energy generation unit  400 - 7 , and may simultaneously maintain constant performance of the optical system  100 . 
     The camera module  1007  may further include a component other than the components described above. For example, the camera module  1007  may further include the housing  500 , the substrate  600 , the cover member  700 , etc. 
     The housing  500  (including the upper and lower housings  510  and  520 ) may accommodate or support the lens barrel  200 - 7  and the substrate  600 . For example, the housing  500  may accommodate the substrate  600  while supporting the lens barrel  200 - 7  and the substrate  600 . 
     The substrate  600  may include an electronic component required to drive the camera module  1007 . For example, the substrate  600  may be equipped with the image sensor  610 , the passive element  620  and the like. The electronic components mounted on or embedded in the substrate  600  may be electrically connected to each other. For example, the electric circuit electrically connecting the electronic components to each other may be formed on the one surface of or in the substrate  600 . The substrate  600  may provide power and a control signal that are necessary to drive the camera module  1007 . For example, the connection terminal  630  connected to the external power source and the external device may be formed on the rear surface of the substrate  600 . The substrate  600  may be connected to the energy generation unit  400 - 7 . For example, the power supply terminal  640  connected to the power terminal of the energy generation unit  400 - 7  may be formed on the one surface of the substrate  600 . The energy generation unit  400 - 7  and the power supply terminal  640  may be electrically connected to each other by the power line  642 , the flexible substrate or the like. 
     The cover member  700  may secure the forwardmost lens to the lens barrel  200 - 7 . For example, the cover member  700  may be coupled to the lens barrel  200 - 7  while pressing the edge of the first lens  110 . The cover member  700  may be adhered or coupled to the lens barrel  200 - 7 . As an example, the cover member  700  may be adhered to the lens barrel  200 - 7  by the adhesive member. As another example, the cover member  700  may be fastened to the lens barrel  200 - 7  by screw coupling. The cover member  700  being adhered to the lens barrel  200 - 7  by the adhesive member may improve the airtightness between the cover member  700  and the lens barrel  200 - 7 , and the latter example may increase the adhesion between the first lens  110  and the lens barrel  200 - 7  by the cover member  700 . 
     The cover member  700  may be generally made of the material that is the same as or similar to that of the lens barrel  200 - 7 . For example, the cover member  700  may be made of a plastic material. The cover member  700 , which is made of the material which is the same as or similar to that of the lens barrel  200 - 7 , may be excellently coupled, adhered or fastened to the lens barrel  200 - 7 , and may thus significantly reduce the possibility that the front lens (i.e., first lens  110 ) is separated from the lens barrel  200 - 7 . However, the cover member  700  is not limited to the plastic material. For example, the cover member  700  may be made of a metal material to protect the first lens  110  from the external impact. 
     The airtight member  800  may be disposed between the first lens  110  and the cover member  700 . For example, the airtight member  800  may be disposed between the step portion  117 , formed on the edge of the first lens  110 , and the cover member  700 . The airtight member  800  may be made of the material that may be elastically deformed or compressively deformed. For example, the airtight member  800  may be made of rubber, synthetic rubber, elastomer, or the like. However, the airtight member  800  is not limited to the above-mentioned material. The airtight member  800  may block the gap between the first lens  110  and the cover member  700 . For example, the airtight member  800  may be elastically deformed when the cover member  700  and the lens barrel  200 - 7  are coupled to each other to block the gap between the first lens  110  and the cover member  700 . 
     The camera module  1007  may further include another airtight member. For example, an airtight member  820  may be additionally disposed between the second lens barrel  200 - 7  and the barrel holder  300 - 7 . The airtight member  820  may block external air and moisture from penetrating through a gap between the lens barrel  200 - 7  and the barrel holder  300 - 7 . For example, the airtight member  820  may be disposed between a top end of the lens barrel  200 - 7  and a top end of the barrel holder  300 - 7 . The airtight member  820  may allow the lens barrel  200 - 7  to be aligned with the optical axis based on the barrel holder  300 - 7 . For example, the airtight member  820  may have predetermined elastic force and elastic deformation force, and may thus allow the lens barrel  200 - 7  to be aligned with the optical axis based on the barrel holder  300 . 
       FIGS. 26A through 27B  illustrate other types of a lens barrel and an energy generation unit, according to embodiments. 
     The lens barrel and the energy generation unit may have improved efficiency of supplying the energy transferred to the first lens  110 . As an example, the lens barrel and the energy generation unit may allow the energy generation unit and the first lens  110  to be in direct contact with each other. As another example, the lens barrel may further include a member having high energy transfer efficiency. 
     Referring to  FIGS. 26A and 26B , a lens barrel  200 - 8  and energy generation unit  400 - 8  may have grooves and protrusions, respectively. For example, a plurality of grooves  208  may be formed in the flange portion  206  of a lens barrel  200 - 8 , and a plurality of protrusions  408  may be formed in an energy generation unit  400 - 8 . The grooves  208  may penetrate through the flange portion  206  in a vertical direction, and may be spaced apart from each other in a circumferential direction of the flange portion  206 . The same number of protrusions  408  may be disposed in the grooves  208 , and the protrusion  408  may be inserted into the groove  208  to protrude at the same height as a top surface of the flange portion  206  or higher than the top surface of the flange portion  206 . 
     The lens barrel  200 - 8  and energy generation unit  400 - 8  may be coupled to each other by the grooves  208  and protrusions  408 . For example, the energy generation unit  400 - 8  may be coupled to the lens barrel  200  by the protrusion  408  inserted into the groove  208 . 
     The energy generation unit  400 - 8  may be in direct contact with the first lens  110 . For example, the energy generation unit  400 - 8  may be in direct contact with the first lens  110  by the protrusion  408  exposed or protruding from the surface of the flange portion  206 . Therefore, the energy of the energy generation unit  400 - 8  may be rapidly transferred to the first lens  110  through the protrusion  408 , thereby removing foreign matter adhering to the surface of the first lens  110 . 
       FIGS. 27A and 27B  illustrate another type of the lens barrel, according to an embodiment. 
     Referring to  FIGS. 27A and 27B , a lens barrel  200 - 9  may include a component configured to rapidly transfer the energy of the energy generation unit  400 - 6 . For example, a reinforcing member  205  may be formed on the flange portion  206  of the lens barrel  200 - 9 . The reinforcing member  205  may be made of a different material from that of the lens barrel  200 - 9 . For example, the lens barrel  200 - 9  may be made of a plastic material, and the reinforcing member  205  may be made of a metal material. However, the material of the reinforcing member  205  is not limited to the metal. For example, the reinforcing member  205  may be made of any other material as long as the reinforcing member  205  may transfer thermal energy and vibration energy. As an example, the reinforcing member  205  may be made of a ceramic material which may transfer vibration energy. The reinforcing member  205  may be integrally formed with the lens barrel  200 - 9 . For example, the reinforcing member  205  may be integrally formed with the flange portion  206  of the lens barrel  200 - 9  by insert injection. However, the reinforcing member  205  is not limited to being formed by the insert injection method. 
     The energy generated by the energy generation unit  400 - 6  may be transferred to the first lens  110  through the reinforcing member  205 . For example, the thermal energy of the energy generation unit  400 - 6  may be rapidly transferred to the first lens  110  through the reinforcing member  205  made of the metal material, and may hardly be transferred to the first lens  110  through the lens barrel  200 - 9  and the flange portion  206  made of the plastic material. Accordingly, the energy generated by the energy generation unit  400 - 6  may be transferred to none of the second to fifth lenses  120  to  150  accommodated in the lens barrel  200 - 9 . That is, the lens barrel  200 - 9  may transfer most of the energy generated by the energy generation unit  400 - 6  only to the first lens  110 . 
     Therefore, the lens barrel  200 - 9  and the energy generation unit  400 - 6  may be useful for rapidly removing foreign matter adhering to the first lens  110 . 
       FIG. 28  illustrates a camera module, according to another embodiment. 
     Referring to  FIG. 28 , a camera module  1008  may include the optical system  100 , a lens barrel  200 - 10 , a barrel holder  300 - 10 , an energy generation unit  400 - 10  and a heat dissipation member  900 . 
     The optical system  100  may form an image at a predetermined position by using the light reflected from a subject. For example, the optical system  100  may have a refractive power to form the image at the predetermined position by using the light incident thereon. The optical system  100  may include the plurality of lenses. For example, the optical system  100  may include the five or more lenses including the first to fifth lenses  110 ,  120 ,  130 ,  140  and  150 . However, the number of lenses included in the optical system  100  is not limited to five. For example, the optical system  100  may include four or fewer lenses or include six or more lenses. 
     The forwardmost lens (i.e., first lens  110 ) of the optical system  100 , which is disposed closest to the object side, may have a larger diameter than the other lenses. For example, the first lens  110  may be sized to be in contact with the end of the lens barrel  200 - 10 . 
     The optical system  100  may further include another component in addition to the lens. For example, the optical system  100  may further include a filter member configured to block the infrared light. However, the additional component of the optical system  100  is not limited to the filter member. For example, the optical system  100  may further include a stop disposed between the lens and the lens to control the amount of light, the spacer maintaining a constant distance between the lens and the lens, etc. However, the optical system  100  may not necessarily include the filter member, the stop, the spacer, and the like. For example, the optical system  100  may omit the filter member or the spacer as needed. 
     The optical system  100  may have a predetermined angle of view. For example, the optical system  100  may have an angle of view of 120 degrees or more to simultaneously capture the image over a wide area. However, the angle of view of the optical system  100  is not limited to 120 degrees or more. For example, the optical system  100  may have an angle of view of less than 120 degrees. 
     The lens barrel  200  may accommodate the optical system  100 . For example, the lens barrel  200 - 10  may include the accommodation space accommodating the optical system  100 . The lens barrel  200 - 10  may accommodate one or more of the first to fifth lenses  110  to  150  included in the optical system  100 . For example, the lens barrel  200 - 10  may accommodate the second to fifth lenses  120  to  150 . 
     The lens barrel  200 - 10  may generally have a cylindrical shape. However, the lens barrel  200 - 10  is not limited to the cylindrical shape. For example, the lens barrel  200  may have the shape of a quadrangular prism, a rectangular prism, or the like based on a cross-sectional shape of the lenses. 
     The lens barrel  200 - 10  may minimize change in the performance of the optical system  100  based on the change in the temperature of the external environment. For example, the lens barrel  200 - 10  may be made of a material having low thermal conductivity to minimize the external heat or cold air from being transferred to the first to fifth lenses  120 ,  130 ,  140  and  150  in the accommodation space. For example, the lens barrel  200 - 10  may be made of a plastic material. However, the lens barrel  200 - 10  is not limited to the plastic material. 
     The barrel holder  300 - 10  may be coupled to the lens barrel  200 - 10 . For example, the barrel holder  300 - 10  may be coupled with the lens barrel  200 - 10  by a screw coupling, a press-fit, adhesive fixation, etc. The barrel holder  300  may secure the lens barrel  200 - 10  to a body of the camera module  1008 . For example, the barrel holder  300 - 10  may be fixed to the housing  500  while being coupled with the lens barrel  200 . The barrel holder  300 - 10  may be coupled with the substrate  600 . For example, the barrel holder  300 - 10  may be coupled with the substrate  600  by using the bolt, the screw, an adhesive, or the like. The barrel holder  300 - 10  may adjust a distance between the lens barrel  200 - 10  and the substrate  600 . For example, the barrel holder  300 - 10  may change a position where the barrel holder  300 - 10  is coupled with the lens barrel  200 - 10  to adjust a distance (LP) from an end of the lens barrel  200 - 10  to the substrate  600  and the back focal length (BLF, that is, the distance from the image side of the rearmost lens  150  to the top surface of the image sensor  610 ) of the optical system  100 . 
     The barrel holder  300 - 10  may be in contact with the forwardmost lens. For example, the barrel holder  300 - 10  may be in contact with an outer circumferential surface of the first lens  110 . In modified examples, a barrel holder and the first lens  110  may maximize an area in which the barrel holder and the first lens  110  are in contact with each other. As an example, a barrel holder  300 - 11  and the first lens  110  may increase the contact area therebetween by using an inclined surface  307  and the inclined surface  114  in contact with each other, as shown in  FIG. 29A . As another example, a barrel holder  300 - 12  and the first lens  110  may increase the contact area therebetween by using a stair  308  and a stair  116  meshing with each other, as shown in  FIG. 29B . The barrel holder  300 - 11 / 300 - 12  and the first lens  110  as described above may allow the barrel holder  300 - 11 / 300 - 12  and the first lens  110  to have improved coupling force therebetween, and allow energy to be easily transferred between the barrel holder  300 - 11 / 300 - 12  and the first lens  110 . It is to be understood that the following description of the barrel holder  300 - 10  of  FIG. 28  also applies to the barrel holders  300 - 1  and  300 - 12  of  FIGS. 29A and 29B . 
     The barrel holder  300 - 10  may be made of a material that may easily transfer the energy generated from the energy generation unit  400 . For example, the barrel holder  300 - 10  may be made of a metal material having high thermal conductivity. However, the barrel holder  300 - 10  is not limited to the metal material. 
     The barrel holder  300 - 10  may be coupled with the housing  500 . For example, the barrel holder  300 - 10  may be coupled with the housing  500  by a screw coupling, a press-fit, the adhesive, etc. The barrel holder  300 - 10  may include a component determining a portion where the barrel holder  300 - 10  is fixed to the housing  500 . For example, the barrel holder  300 - 10  may include a flange portion  306  in contact with an end of the housing  500 . The flange portion  306  may be fixed to the housing  500  by the adhesive. 
     The energy generation unit  400 - 10  may be disposed in the barrel holder  300 - 10 . For example, the energy generation unit  400 - 10  may be disposed on an outer circumferential surface of the barrel holder  300 - 10 . The energy generation unit  400 - 10  may provide the energy to the first lens  110 . For example, the energy generation unit  400 - 10  may indirectly provide the energy to the first lens  110  through the barrel holder  300 - 10 . The energy generation unit  400 - 10  may easily provide the energy to the first lens  110 . For example, the energy generation unit  400 - 10  may be disposed adjacent to the first lens  110  on the outer circumferential surface of the barrel holder  300 - 10 . However, the position at which the energy generation unit  400 - 10  is disposed is not limited to the above-described position. 
     The energy generation unit  400 - 10  may generate a predetermined amount of energy. As an example, the energy generation unit  400 - 10  may provide the thermal energy. As an example, the energy generation unit  400 - 10  may be a PTC heater  420 , as shown in  FIG. 30A . The PTC heater  420  may have a film shape. The film-shaped PTC heater  420  may be freely bent to be deformed, and may thus be easily attached or disposed on the outer circumferential surface of the barrel holder  300 - 10 . However, the shape of heat generation device  410 - 10  is not limited to the PTC heater. In addition, a PTC heater is not limited to the film shape. For example, a PTC heater  420  may have the disk shape, similar to the shape of a vibration device  430  shown in  FIG. 30B . 
     As another example, the energy generation unit  400 - 10  may provide the vibration energy. As a specific example, the energy generation unit  400 - 10  may be the vibration device  430 . The vibration device may generally have a disk shape similar to that shown for the PTC heater  430  in  FIG. 30B . However, the vibration device is not limited to the disk shape. 
     The heat dissipation member  900  may be disposed on the barrel holder  300 - 10 . For example, the heat dissipation member  900  may be disposed on the outer circumferential surface of the barrel holder  300 - 10 . However, the position at which the heat dissipation member  900  is disposed is not limited to the outer circumferential surface of the barrel holder  300 . The heat dissipation member  900  may easily dissipate heat. As an example, the heat dissipation member  900  may be made of copper, aluminum, or an alloy of copper and aluminum, having high thermal conductivity. However, the heat dissipation member  900  is not limited to the material of copper or aluminum. As another example, the heat dissipation member  900  may include a plurality of heat dissipation fins  910  to increase a contact area between the heat dissipation member  900  and the external air. The heat dissipation fin  910  may be formed on a surface of the heat dissipation member  900  to outwardly dissipate heat transferred to the heat dissipation member  900 . 
     The heat dissipation member  900  may prevent overheating of the camera module  1008 . As an example, the heat dissipation member  900  may prevent overheating of the optical system  100 . As a specific example, the heat dissipation member  900  may absorb heat from the first lens  110  overheated by the incident light thereon, and dissipate the heat outward. Alternatively, the heat dissipation member  900  may absorb heat from the first lens  110  overheated by the energy generation unit  400 - 10 , and dissipate the heat outward. The heat of the first lens  110  may be transferred to the heat dissipation member  900  through the metal barrel holder  300 - 10 . As another example, the heat dissipation member  900  may prevent overheating of a control device of the camera module  1008 . As a specific example, the heat dissipation member  900  may absorb heat from the substrate  600  and the image sensor  610  through the metal barrel holder  300 - 10  to dissipate the heat outward. As yet another example, the heat dissipation member  900  may prevent overheating of the energy generation unit  400 - 10 . For example, the heat dissipation member  900  may be in direct contact with the energy generation unit  400 - 10 , thereby dissipating outward, some of the heat generated during an operation of the energy generation unit  400 - 10 . 
     The camera module  1008  may further include a component other than the components described above. For example, the camera module  1008  may further include the housing  500 , the substrate  600 , the cover member  700 , etc. 
     The housing  500  may accommodate or support the lens barrel  200 - 10 , barrel holder  300 - 10 , and the substrate  600 . For example, the housing  500  may accommodate the lens barrel  200 - 10 , the barrel holder  300 - 10 , and the substrate  600 , and may be coupled with the barrel holder  300 - 10  to firmly support the lens barrel  200 - 10  and the substrate  600  for the lens barrel  200  and the substrate  600  not to be shaken by the external impact. 
     The substrate  600  may include an electronic component required to drive the camera module  1008 . For example, the substrate  600  may be equipped with the image sensor  610 , the passive element  620 , and the like. The electronic components mounted on or embedded in the substrate  600  may be electrically connected to each other. For example, the electric circuit electrically connecting the electronic components to each other may be formed on the one surface of or in the substrate  600 . The substrate  600  may provide power and a control signal that are necessary to drive the camera module  1008 . For example, the connection terminal  630  connected to the external power source and the external device may be formed on the rear surface of the substrate  600 . The substrate  600  may be connected to the energy generation unit  400 - 10 . For example, the power supply terminal  640  connected to the power terminals  402  and  404  of the energy generation unit  400 - 10  may be formed on the one surface of the substrate  600 . The energy generation unit  400 - 10  and the power supply terminal  640  may be electrically connected to each other by the power line  642 , the flexible substrate, or the like. 
     The airtight member  800  may maintain the airtightness of the energy generation unit  400 - 10 . For example, the airtight member  800  may be disposed between the barrel holder  300 - 10  and the heat dissipation member  900 . However, the position where the airtight member  800  is disposed is not limited to the position between the barrel holder  300 - 10  and the heat dissipation member  900 . For example, the airtight member  800  may also be disposed between the first lens  110  and the barrel holder  300 - 10 , between the lens barrel  200 - 10  and the barrel holder  300 - 10 , etc. The airtight member  800  may be made of a material that may be elastically deformed or compressively deformed. For example, the airtight member  800  may be made of rubber, synthetic rubber, elastomer or the like. However, the airtight member  800  is not limited to the above-mentioned material. The airtight member  800  may block the gap between the first lens  110  and the cover member  700 . For example, the airtight member  800  may be elastically deformed when the cover member  700  and the lens barrel  200 - 10  are coupled to each other to block the gap between the first lens  110  and the cover member  700 . 
     The camera module  1008  configured may remove foreign matter adhering to the front lens (i.e., first lens  110 ). For example, the camera module  1008  may evaporate a liquid foreign material such as a raindrop, frost, dew and moisture adhering to the surface of the first lens  110 , thereby removing the same. In addition, the camera module  1008  may absorb the heat of the first lens  110  and substrate  600  through the heat dissipation member  900  to prevent the overheating of the first lens  110  and substrate  600 . 
       FIG. 31  illustrates a camera module, according to another embodiment. 
     Referring to  FIG. 31 , a camera module  1008   a  may further include the glass cover panel  102 , in addition to the elements included in the camera module  1008  in  FIG. 28 . The glass cover panel  102  may be disposed in front of the first lens  110 . The glass cover panel  102  may not affect the performance of the optical system  100 . For example, the glass cover panel  102  may transmit the light incident thereon as it is, without refracting the light. The glass cover panel  102  may be resistant to an external impact. For example, the glass cover panel  102  may be made of the glass material resistant to an external impact. However, the material of the glass cover panel  102  is not limited to the glass. 
     The glass cover panel  102  may be coupled with the barrel holder  300 - 10 . For example, the glass cover panel  102  may be coupled to the barrel holder  300 - 10  by a separate fixation member  700 . However, the coupling between the glass cover panel  102  and the barrel holder  300 - 10  is not limited to the coupling therebetween by the fixation member  700 . As an example, the glass cover panel  102  may be adhered to the barrel holder  300 - 10  by an adhesive. 
     The energy generation unit  400 - 10  may provide the energy to the first lens  110 . In addition, the energy generation unit  400 - 10  may provide additional energy to the glass cover panel  102 . For example, energy generated from the energy generation unit  400 - 10  may be transferred to the first lens  110  through the barrel holder  300 - 10  to heat the first lens  110 , and heat radiant from the heated first lens  110  may be transferred to the glass cover panel  102 . The energy provided to the glass cover panel  102  may remove the foreign matter adhering to the glass cover panel  102 . As an example, the thermal energy provided to the glass cover panel  102  may evaporate frost, moisture, a water droplet, or the like, adhering to the surface of the glass cover panel  102 . As another example, vibration energy provided to the glass cover panel  102  may separate dust adhering to the surface of the glass cover panel  102  therefrom. 
     The energy generation unit  400 - 10  may be selected from the heat generation device, the vibration device, etc. As an example, the energy generation unit  400 - 10  may be the PTC heater  420  in the film shape shown in  FIGS. 29A and 29B . As another example, the energy generation unit  400 - 10  may be the vibration device  430  shown in  FIGS. 30A and 30B . As yet another example, the energy generation unit  400 - 10  may have a shape in which the PTC heater  420  and the vibration device  430  are integrated with each other. However, the energy generation unit  400 - 10  is not limited to the above-mentioned devices. 
     In the camera module  1008   a , the glass cover panel  102  may be disposed in front of the first lens  110 , and it is thus possible to reduce a possibility that the first lens  110  is damaged by an external impact. In addition, the camera module  1008   a  may remove foreign matter adhering to the glass cover panel  102  as well as the first lens  110  by using the energy generation unit  400 - 10 , thereby reducing resolution degradation and a blocked field of view caused by the foreign matter. 
     A camera module, according to other embodiments, may provide energy to an optical member positioned at a forwardmost position of the camera module. For example, the camera module may provide the energy to a forwardmost lens or a forwardmost glass cover panel to remove the foreign matter adhering to the forwardmost lens or forwardmost glass cover panel. 
       FIG. 32  illustrates a camera module configured to provide energy to an optical member positioned at the forwardmost position of a camera module, according to an embodiment. 
     Referring to  FIG. 32 , a camera module  1009  may include the optical system  100 , a lens barrel  200 - 13 , a barrel holder  300 - 13 , an energy generation unit  400 - 13 , the housing  500 , the substrate  600 , and the cover member  700 . 
     The optical system  100  may form an image at a predetermined position by using the light reflected from a subject. For example, the optical system  100  may have a refractive power to form the image at the predetermined position by using the light incident thereon. The optical system  100  may include three or more lenses including the first to third lenses  110 ,  120  and  130 . However, the number of lenses included in the optical system  100  is not limited to three. For example, the optical system  100  may include four or more lenses. 
     The optical system  100  may further include another component in addition to the first to third lenses  110 ,  120  and  130 . For example, the optical system  100  may further include a filter member (IF) configured to block infrared light. However, the additional component of the optical system  100  is not limited to the filter member (IF). For example, the optical system  100  may further include a stop disposed between the lens and the lens to control the amount of light, a spacer maintaining a constant distance between the lens and the lens, etc. However, the optical system  100  may not necessarily include the filter member, the stop, and the spacer. For example, the optical system  100  may omit the filter member or the spacer as needed. 
     The optical system  100  may have a predetermined angle of view. For example, the optical system  100  may have an angle of view of 120 degrees or more to simultaneously capture the image over a wide area. However, the angle of view of the optical system  100  is not limited to 120 degrees or more. For example, the optical system  100  may have an angle of view of less than 120 degrees. 
     The optical system  100  may further include the glass cover panel  102 . The glass cover panel  102  may be disposed in front of the first lens  110 . The glass cover panel  102  may not affect the performance of the optical system  100 . For example, the glass cover panel  102  may transmit the light incident thereon as it is, without refracting the light. The glass cover panel  102  may be resistant to an external impact. For example, the glass cover panel  102  may be made of the glass material resistant to an external impact. However, the material of the glass cover panel  102  is not limited to the glass. 
     The lens barrel  200 - 13  may accommodate the optical system  100 . For example, the lens barrel  200  may include the accommodation space accommodating the optical system  100 . The lens barrel  200 - 13  may generally have the cylindrical shape. However, the lens barrel  200 - 13  is not limited to the cylindrical shape. For example, the lens barrel  200 - 13  may have the shape of a quadrangular prism, a rectangular prism, or the like, based on a cross-sectional shape of the lenses. 
     The lens barrel  200 - 13  may minimize the change in the performance of the optical system  100  based on the change in the temperature of the external environment. For example, the lens barrel  200 - 13  may be made of a material having low thermal conductivity to minimize the external heat or cold air from being transferred to the first to third lenses  110 ,  120  and  130  in the accommodation space. For example, the lens barrel  200 - 13  may be made of a plastic material. However, the lens barrel  200 - 13  is not limited to the plastic material. 
     The barrel holder  300 - 13  may be coupled to the lens barrel  200 - 13  and the substrate  600 . For example, one end of the barrel holder  300 - 13  may be coupled to the lens barrel  200 - 13 , and the other end thereof may be coupled to the substrate  600 . The barrel holder  300 - 13  may adjust the distance between the lens barrel  200  and the substrate  600 . For example, the barrel holder  300 - 13  may change a position at which the barrel holder  300 - 13  is coupled with the lens barrel  200 - 13  to adjust the distance from an end of the lens barrel  200 - 13  to the substrate  600 . 
     The barrel holder  300 - 13  may be made of a material that is substantially the same as or similar to that of the lens barrel  200 - 13 . For example, the barrel holder  300 - 13  may be made of a plastic material. However, the barrel holder  300 - 13  is not limited to a plastic material. For example, the barrel holder  300 - 13  may be made of any other material as long as the barrel holder  300 - 13  may be adhered or fastened to the lens barrel  200 - 13 . 
     The energy generation unit  400 - 13  may remove foreign matter adhering to the glass cover panel  102 . For example, the energy generation unit  400 - 13  may be disposed between the glass cover panel  102  and the first lens  110  to directly provide energy required to remove the foreign matter adhering to the glass cover panel  102  from the glass cover panel  102 . However, the energy generation unit  400 - 13  is not limited to the above-described shape. 
     The energy generation unit  400 - 13  may generate thermal energy. For example, the energy generation unit  400 - 13  may be a heat generation device  410 - 13  including power terminals  411  and  413  and a heating member  418 . The power terminals  412 - 13  and  414  may be electrically connected to the substrate  600 . For example, the power terminals  411  and  413  may be connected to the power supply terminal of the substrate  600  by the flexible substrate or a wire. However, the electrical connection between the power terminals  411  and  413  and the substrate  600  is not limited to the flexible substrate and the wire. For example, the power terminals  411  and  413  may be electrically connected to the substrate  600  by a molded interconnected device MID (e.g., printed circuit) formed on the lens barrel  200 - 13  and the barrel holder  300 - 13 . 
     The heating member  418  may be formed on one surface of the first lens  110 . For example, the heating member  418  may be formed on the object-side surface of the first lens  110 . However, the position at which the heating member  418  is formed is not limited to the surface of the first lens  110 . For example, the heating member  418  may be formed on one surface of the glass cover panel  102 . The heating member  418  may remove liquid foreign material adhering to the first lens  110  and glass cover panel  102 . For example, the heating member  418  may heat the first lens  110  or the glass cover panel  102 , thereby evaporating the liquid foreign material adhering to the first lens  110  or glass cover panel  102 . The heating member  418  may be a resistor that dissipates heat by electric current supplied from the power terminals  411  and  413 . The heating member  418  may be disposed between the glass cover panel  102  and the first lens  110 . For example, the heating member  418  may have the film shape to be disposed in a narrow space between the glass cover panel  102  and the first lens  110 . However, the heating member  418  may not necessarily have the film shape. The heating member  418  may have a shape allowing the light to pass therethrough. For example, the heating member  418  may be a transparent film on which an indium tin oxide (ITO) electrode is formed. 
     The housing  500  may accommodate or support the lens barrel  200 - 13 , the barrel holder  300 - 13  and the substrate  600 . For example, the housing  500  may accommodate the lens barrel  200 , the barrel holder  300  and the substrate  600 , and may firmly support the substrate  600  by interposing a support member  512  therebetween. The housing  500  may be made of the material resistant to the external impact. For example, the housing  500  may be made of the metal material. However, the housing  500  is not limited to the metal material. For example, the housing  500  may be made of the material which is the same as or similar to that of the barrel holder  300 - 13  to be easily bonded or fused to the barrel holder  300 - 13 . 
     The substrate  600  may include an electronic component required to drive the camera module  1009 . For example, the substrate  600  may be equipped with the image sensor  610 , the passive element  620 , and the like. The electronic components mounted on or embedded in the substrate  600  may be electrically connected to each other. For example, the electric circuit electrically connecting the electronic components to each other may be formed on the one surface of or in the substrate  600 . The substrate  600  may provide power and a control signal that are necessary to drive the camera module  1009 . 
     The cover member  700  may secure the glass cover panel  102  and the first lens  110  to the lens barrel  200 - 13 . The cover member  700  may be coupled to the lens barrel  200 - 13  or the housing  500 . As another example, the cover member  700  may be fastened to the lens barrel  200 - 13  by a screw coupling. As another example, the cover member  700  may be fixed to the housing  500  by adhesive. However, the coupling between the cover member  700 , the lens barrel  200 - 13  and the housing  500  is not limited to the above-described method. 
     The cover member  700  may improve the airtightness by using the airtight member  800 . For example, the cover member  700  may press the airtight member  800  while being coupled to the lens barrel  200 - 13  for the airtight member  800  to be elastically deformed or compressively deformed. The airtight member  800 , when elastically deformed or compressively deformed, may block a minute gap between the glass cover panel  102  and the lens barrel  200 - 13 . Therefore, the airtight member  800  pressed by the cover member  700  may block the gap between the glass cover panel  102  and the lens barrel  200 - 13  more firmly. 
     The airtight member  800  may block the gap between the glass cover panel  102  and the cover member  700 . For example, the airtight member  800  may be disposed between the glass cover panel  102  and the cover member  700  to block the external air or the foreign matter from intruding into the gap between the glass cover panel  102  and the cover member  700 . However, the position at which the airtight member  800  is disposed is not limited to the position between the glass cover panel  102  and the member  700 . The airtight member  800  may be made of a material which may be elastically deformed or compressively deformed. For example, the airtight member  800  may be made of rubber, synthetic rubber, elastomer or the like. However, the airtight member  800  is not limited to the above-mentioned material. 
     In the first-type camera module  1009 , the energy generation unit  400 - 13  may be disposed between the first lens  110  and the glass cover panel  102 , thereby protecting the energy generation unit  400 - 13  from the external impact and also removing foreign matter adhering to the glass cover panel  102 . 
       FIG. 33  illustrates a camera module configured to provide energy to an optical member positioned at the forwardmost position of a camera module, according to an embodiment. 
     Referring to  FIG. 33 , a camera module  1009   a , according to an embodiment, may include the optical system  100 , the lens barrel  200 - 13 , the barrel holder  300 - 13 , an energy generation unit  400 - 14 , the housing  500 , the substrate  600 , and the cover member  700 . 
     The optical system  100  may form an image at a predetermined position by using the light reflected from a subject. For example, the optical system  100  may have a refractive power to form the image at the predetermined position by using the light incident thereon. The optical system  100  may include four or more lenses, including first to fourth lenses  110 ,  120 ,  130  and  140 . However, the number of lenses included in the optical system  100  is not limited to four. For example, the optical system  100  may include five or more lenses. 
     The optical system  100  may further include another component in addition to the lens. For example, the optical system  100  may further include a filter member configured to block infrared light. However, the additional component of the optical system  100  is not limited to the filter member. For example, the optical system  100  may further include a stop disposed between the lens and the lens to control the amount of light, the spacer maintaining a constant distance between the lens and the lens, etc. However, the optical system  100  may not necessarily include the filter member, the stop, and the spacer. For example, the optical system  100  may omit the filter member or the spacer as needed. 
     The optical system  100  may have a predetermined angle of view. For example, the optical system  100  may have an angle of view of 120 degrees or more to simultaneously capture the image over a wide area. However, the angle of view of the optical system  100  is not limited to 120 degrees or more. For example, the optical system  100  may have the angle of view of less than 120 degrees. 
     The lens barrel  200 - 13  may accommodate the optical system  100 . For example, the lens barrel  200 - 13  may include the accommodation space accommodating the optical system  100 . The lens barrel  200 - 13  may generally have the cylindrical shape. However, the lens barrel  200 - 13  is not limited to the cylindrical shape. For example, the lens barrel  200 - 13  may have the shape of a quadrangular prism, a rectangular prism, or the like, based on a cross-sectional shape of the lenses. 
     The lens barrel  200 - 13  may minimize the change in the performance of the optical system  100  based on the change in the temperature of the external environment. For example, the lens barrel  200 - 13  may be made of a material having low thermal conductivity to minimize the external heat or cold air from being transferred to the second to third lenses  120 ,  130  and  140  in the accommodation space. For example, the lens barrel  200 - 13  may be made of the plastic material. However, the lens barrel  200 - 13  is not limited to the plastic material. 
     The barrel holder  300 - 13  may be coupled to the lens barrel  200 - 13  and the substrate  600 . For example, one end of the barrel holder  300 - 13  may be coupled to the lens barrel  200 - 13 , and the other end thereof may be coupled to the substrate  600 . The barrel holder  300 - 13  may adjust the distance between the lens barrel  200 - 13  and the substrate  600 . For example, the barrel holder  300 - 13  may change the position at which the barrel holder  300 - 13  is coupled with the lens barrel  200 - 13  to adjust the distance from an end of the lens barrel  200 - 13  to the substrate  600 . 
     The barrel holder  300 - 13  may be made of a material which is substantially the same as or similar to that of the lens barrel  200 - 13 . For example, the barrel holder  300 - 13  may be made of the plastic material. However, the barrel holder  300 - 13  is not limited to the plastic material. For example, the barrel holder  300 - 13  may be made of any other material as long as the barrel holder  300 - 13  may be adhered or fastened to the lens barrel  200 - 13 . 
     The energy generation unit  400 - 13  may use magnetic energy. For example, the energy generation unit  400 - 13  may be a magnetic induction device  450 . The magnetic induction device  450  may include an electrode terminal  452  and a magnetic induction film  456 . 
     The electrode terminal  452  may be formed on the first lens  110  or the lens barrel  200 . The electrode terminal  452  may be electrically connected to the magnetic induction film  456 . The electrode terminal  452  may be electrically connected to the substrate  600 . For example, the electrode terminal  452  may be connected to the power supply terminal  640  of the substrate  600  by the flexible substrate or the wire. However, the electrical connection between the electrode terminal  452  and the power supply terminal  640  is not limited to the flexible substrate and the wire. For example, the electrode terminal  452  may be electrically connected to the substrate  600  or the power supply terminal  640  by a molded interconnected device MID (e.g., printed circuit) formed on the lens barrel  200  and the barrel holder  300 . 
     The magnetic induction film  456  may be formed on the surface of the first lens  110 . The magnetic induction film  456  may not affect the feature of the optical system  100 . For example, the magnetic induction film  456  may be made of a light-transmitting material. The magnetic induction film  456  may form a predetermined magnetic field on the surface of the first lens  110 . For example, an electrode or an electric circuit, which may form the magnetic field, may be formed on the magnetic induction film  456 . The electrode and electric circuit of the magnetic induction film  456  may each be made of a transparent material. For example, the electrode and electrical circuit of the magnetic induction film  456  may each be formed of the ITO. 
     The magnetic induction device  450  may form the magnetic field on the surface of the first lens  110 . For example, the magnetic induction device  450  may generate a stronger electromotive force at a center of the first lens  110  than at the edge of the first lens  110 . The magnetic field and the electromotive force, generated by the magnetic induction device  450 , may remove foreign matter adhering to the surface of the first lens  110 . For example, the foreign matter adhering to the first lens  110  has a tendency to be moved from the center of the first lens  110  to the edge of the first lens  110  by the magnetic field caused by the magnetic induction device  450 . Accordingly, as time passes, the foreign matter may be collected on the edge of the first lens  110  or separated outward from the first lens  110 . Therefore, according to this embodiment, it is possible to remove foreign matter adhering to the first lens  110  without heating or vibrating the first lens  110 . 
     The housing  500  may accommodate one or more of the lens barrel  200 - 13 , the barrel holder  300 - 13  and the substrate  600 . For example, the substrate  600  may be disposed in the housing  500 . The housing  500  may be coupled with the barrel holder  300 - 13 . For example, the housing  500  may be coupled with the barrel holder  300 - 13  by using the adhesive, the bolt fastening, etc. The housing  500  may be made of the material that is resistant to an external impact. For example, the housing  500  may be made of the metal material. However, the housing  500  is not limited to the metal material. For example, the housing  500  may be made of the material which is the same as or similar to that of the barrel holder  300 - 13  to be easily bonded or fused to the barrel holder  300 - 13 . 
     The substrate  600  may include an electronic component required to drive the camera module  1009   a . For example, the substrate  600  may be equipped with the image sensor  610 , the passive element  620 , the power supply terminal  640  and the like. The electronic components mounted on or embedded in the substrate  600  may be electrically connected to each other. For example, the electric circuit electrically connecting the electronic components to each other may be formed on the one surface of or in the substrate  600 . The substrate  600  may provide power and a control signal, necessary to drive the camera module  1009   a.    
     The cover member  700  may secure the glass cover panel  102  and the first lens  110  to the lens barrel  200 - 13 . The cover member  700  may be coupled to the lens barrel  200 - 13  or the housing  500 . As another example, the cover member  700  may be coupled to the lens barrel  200 - 13  by a screw coupling. 
     The cover member  700  may improve the airtightness by using the airtight member  800 . For example, the cover member  700  may press the airtight member  800  while being coupled to the lens barrel  200  for the airtight member  800  to be elastically deformed or compressively deformed. The airtight member  800 , when elastically deformed or compressively deformed, may block the minute gap between the glass cover panel  102  and the lens barrel  200 . Therefore, the airtight member  800  pressed by the cover member  700  may block the gap between the glass cover panel  102  and the lens barrel  200  more firmly. 
     The airtight member  800  may block the gap between the first lens  110  and the cover member  700 . For example, the airtight member  800  may be disposed between the first lens  110  and the cover member  700  to block the external air or the foreign matter from intruding into the gap between the first lens  110  and the cover member  700 . The airtight member  800  may be made of the material which may be elastically deformed or compressively deformed. For example, the airtight member  800  may be made of rubber, synthetic rubber, elastomer, or the like. However, the airtight member  800  is not limited to the above-mentioned material. 
     The camera module  1009   a  co may remove foreign matter adhering to the surface of the first lens  110  by using the magnetic induction device  450  as described above. For example, the second-type camera module  1009   a  may use the magnetic field, thereby removing not only the liquid foreign material also a solid foreign material, adhering to the surface of the first lens  110 . In addition, the second-type camera module  1009   a  may use the magnetic field to disperse outward, foreign matter in the shape of a particle scattered in front of the first lens  110  from the field of view of the first lens  110 . Therefore, the camera module  1009   a  may reduce the resolution degradation caused by fine dust, dust particles, etc. 
     Referring to  FIG. 34 , a camera module  1009   a  may be modified to have a shape shown in  FIG. 34 . For example, a camera module  1009   b  may further include the glass cover panel  102  as shown in  FIG. 34 . In addition, the magnetic induction device  450  of the camera module  1009   b  may be formed on the glass cover panel  102 . 
       FIGS. 35 to 37  illustrate a camera module, according to another embodiment. 
     Referring to  FIGS. 35 to 37 , a camera module  1010  may include the optical system  100 , a lens barrel  200 - 15 , a barrel holder  300 - 15 , a heat generation device  460 , which is a type of the energy generation unit, a housing  500 - 15 , a substrate  600 - 15 , the cover member  700 , and first, second, and third airtight members  810 ,  820 , and  830 . However, the camera module  1010  is not limited to including the above-mentioned members. 
     The optical system  100  may include one or more lenses. For example, the optical system  100  may include the first lens  110  to the fifth lens (not shown) sequentially arranged from the object side. The optical system  100  may have a predetermined angle of view. For example, the optical system  100  may have an angle of view of 120 degrees or more to simultaneously capture the image over a wide area. However, the angle of view of the optical system  100  is not limited to 120 degrees or more. For example, the optical system  100  may have an angle of view of less than 120 degrees. 
     The first lens  110  may be disposed at the forwardmost of the optical system  100 . For example, the first lens  110  may be disposed for its (object-side) surface to be partially exposed outward. The first lens  110  may have a predetermined refractive power. For example, the first lens  110  may have positive or negative refractive power. One surface of the first lens  110  may have a convex shape. As an example, the object-side surface of the first lens  110  may have the convex shape. However, the object-side surface of the first lens  110  may not necessarily have the convex shape. 
     The first lens  110  may be easily fixed by the cover member  700 . For example, the flange portion  112  which may be coupled to the cover member  700  may be formed on the edge of the first lens  110 . 
     The lens barrel  200 - 1  may accommodate the optical system  100 . For example, the lens barrel  200 - 15  may include the accommodation space accommodating the optical system  100 . The lens barrel  200 - 15  may accommodate the plurality of lenses. For example, the lens barrel  200 - 15  may accommodate the lenses except for the first lens  110 . 
     There may be the plurality of lens barrels  200 - 15 . For example, the lens barrel  200 - 15  may include a first lens barrel  210 - 15  and a second lens barrel  220 - 15 . The first lens barrel  210  and the second lens barrel  220  may be made of materials that are different from each other. As an example, the first lens barrel  210  may be made of a material having low thermal conductivity or a material having low electrical conductivity, and the second lens barrel  220  may be made of a material having high thermal conductivity or a material having high electrical conductivity. As another example, the first lens barrel  210  may be made of a plastic material, and the second lens barrel  220  may be made of a metal material. 
     The first lens barrel  210 - 15  may accommodate the plurality of lenses. For example, the lens barrel  210 - 15  may accommodate all the lenses except for the first lens  110 . The first lens barrel  210 - 15  may be firmly coupled with another member. For example, a first screw portion  212  and a second screw portion  214  may be formed on the outer circumferential surface of the first lens barrel  210 - 15 . The first screw portion  212  may be formed on a lower portion of the first lens barrel  210 - 15 , and the second screw portion  214  may be formed on an upper portion of the first lens barrel  210 - 15 . However, the positions where the first screw portion  212  and the second screw portion  214  are formed are not limited to the lower and upper portions of the first lens barrel  210 - 15 . 
     The first screw portion  212  may allow the first lens barrel  210 - 15  and the barrel holder  300 - 15  to be coupled to each other. For example, the first screw portion  212  may be screwed with a screw portion  302  formed on an inner circumferential surface of the barrel holder  300 - 15 . However, the coupling between the first lens barrel  210 - 15  and the barrel holder  300 - 15  is not limited to a screw coupling. For example, the first lens barrel  210 - 15  and the barrel holder  300 - 15  may be coupled to each other by using the method such as a press-fit, adhesion, fusion, or the like. The second screw portion  214  may allow the first lens barrel  210 - 15  and the second lens barrel  220 - 15  to be coupled to each other. For example, the second screw portion  214  may be screwed with the first screw portion  212  formed on an inner circumferential surface of the second lens barrel  220 - 15 . However, the coupling between the first lens barrel  210 - 15  and the second lens barrel  220 - 15  is not limited to a screw coupling. For example, the first lens barrel  210 - 15  and the second lens barrel  220 - 15  may be coupled to each other by using the method such as a press-fit, adhesion, fusion, or the like. 
     The first lens barrel  210 - 15  may include a component restricting a position at which the first lens barrel  210 - 15  and the second lens barrel  220 - 15  are coupled to each other. For example, a step  216  may be formed on the outer circumferential surface of the second lens barrel  220 - 15  to restrict the movement range or coupling position of the second lens barrel  220 - 15 . The first lens barrel  210 - 15  may include a component fixing a position of the lens or supporting the lens. For example, a plurality of steps  218  may be formed on the inner circumferential surface of the first lens barrel  210 - 15 . 
     The second lens barrel  220 - 15  may accommodate the first lens  110 . For example, the first lens  110  may be seated inside the second lens barrel  220 - 15 . The second lens barrel  220 - 15  may be coupled with the first lens barrel  210 - 15 . For example, the second lens barrel  220 - 15  may be coupled to the first lens barrel  210 - 15  by the screw portions  214  and  224  being fastened to each other. The second lens barrel  220 - 15  may be coupled with the cover member  700 . For example, the second lens barrel  220 - 15  may be coupled to the cover member  700  by the screw portions  226  and  706  being fastened to each other. 
     The second lens barrel  220 - 15  may function as the energy transfer member. To this end, the second lens barrel  220 - 15  may be made of the material which may easily transfer the energy. For example, the second lens barrel  220 - 15  may be made of the material having high thermal conductivity to easily transfer the thermal energy. As a specific example, the second lens barrel  220 - 15  may be made of copper, aluminum, an alloy of copper and aluminum, or the like. However, the material of the second lens barrel  220 - 15  is not limited to copper or aluminum. For example, the second lens barrel  220 - 15  may be made of a material having high thermal conductivity, other than the metal material. 
     The second lens barrel  220 - 15  may be in contact with the heat generation device  460 , which is an energy generation unit. For example, the second lens barrel  220 - 15  may include an extension  229  in contact with an inner circumferential surface of the heat generation device  460 . The extension  229  may be extended downward from a body of the second lens barrel  220 - 15 . 
     The barrel holder  300 - 15  may be coupled with the first lens barrel  210 - 15 . For example, the barrel holder  300 - 15  may be firmly coupled to the first lens barrel  210 - 15  by the screw portions  302  and  212  being fastened to each other. The barrel holder  300 - 15  may be coupled with the substrate  600 - 15 . For example, the barrel holder  300 - 15  may be coupled with the substrate  600 - 15  by interposing a leg member  350  therebetween. The leg member  350  may be fixed to the substrate  600 - 15  by a bolt. An extraction hole  306  may be formed in the barrel holder  300 - 15 . The extraction hole  306  may be used as an outlet for the power line  642  that connects the power supply terminal  640  of the substrate  600 - 15  and the heat generation device  460  to each other. The barrel holder  300 - 15  may be made of a material having low energy transfer efficiency. For example, the barrel holder  300 - 15  may be made of a plastic material having low thermal conductivity. However, the barrel holder  300 - 15  is not limited to the plastic material. 
     The heat generation device  460  may be disposed between the first lens barrel  210 - 15  and the second lens barrel  220 - 15 . For example, the heat generation device  460  may be disposed between the seating portion  304  of the barrel holder  300 - 15  and the first lens barrel  210 - 15 . However, the position at which the heat generation device  460  is disposed is not limited to a position between the seating portion  304  of the barrel holder  300 - 15  and the first lens barrel  210 - 15 . For example, the position at which the heat generation device  460  is disposed may be changed as long as the heat generation device  460  is in contact with the second lens barrel  220 - 15 . 
     The heat generation device  460  may provide the thermal energy to an adjacent member. For example, the heat generation device  460  may provide the thermal energy to the second lens barrel  220 - 15  having high thermal conductivity. The heat generation device  460  may generate constant thermal energy regardless of time or amount of current. For example, the heat generation device  460  may be a PTC heater always maintained at a constant temperature. 
     The heat generation device  460  may include a heating element  462  and electrodes  464  and  466 . The heating element  462  may have a shape of a ring having one side open, and the electrodes  464  and  466  may each have a disk shape. However, the heating elements  462  and the electrodes  464  and  466  are not limited to the ring and disk shapes, respectively. The heating element  462  may be elastically deformed or its shape may be deformed. Therefore, the heating element  462  may be freely deformed to be inserted into a space where the heat generation device  460  is disposed, and may be in close contact with the second lens barrel  220 - 15 . The heating element  462  may include a component configured to convert electrical energy into the thermal energy. For example, the heating element  462  may be made of a material having high electrical resistance, or may be an electronic component including a plurality of resistance elements. The electrodes  464  and  466  may supply the current to the heating element  462 . The first electrode  464  may be disposed on a top potion of heating element  462 , and the second electrode  466  may be disposed on a bottom portion of the heating element  462 . 
     The heat generation device  460  may supply thermal energy to the first lens  110 . For example, the thermal energy generated from the heat generation device  460  may be transferred to the first lens  110  through the second lens barrel  220 - 15  having high thermal conductivity. The heat generation device  460  may allow foreign matter adhering to the first lens  110  to be removed. For example, the thermal energy generated from the heat generation device  460  may be used as an energy source to evaporate frost, dew, moisture and a water droplet, adhering to the surface of the first lens  110 . 
     The housing  500 - 15  may accommodate the lens barrel  200 - 15 , the barrel holder  300 - 15  and the substrate  600 - 15 . For example, the housing  500 - 15  may accommodate all of the lens barrel  200 - 15 , the barrel holder  300 - 15  and the substrate  600 - 15 . The housing  500 - 15  may include a component that supports the position of the substrate  600 - 15 . For example, a support member  540  which may be coupled to the substrate  600 - 15  while supporting the position of the substrate  600 - 15  may be formed in a lower portion of the housing  500 . The support member  540  may support four corners of the substrate  600 - 15  and may be coupled to the substrate  600 - 15  by a bolt. The housing  500 - 15  may include a component through which input and output cables are extracted. For example, a passage  530  through which the input and output cables are extracted may be formed on one side of the housing  500 - 15 . The housing  500 - 15  may be coupled with the cover member  700 . For example, the housing  500 - 15  may be coupled with the cover member  700  by the method such as adhesion, fitting, screwing, etc. The housing  500 - 15  may be made of a material resistant to impact. For example, the housing  500 - 15  may be made of a metal material. However, the housing  500  is not limited to the metal material. For example, the housing  500  may be made of a plastic material to reduce a weight of the camera module  1010 . 
     The substrate  600 - 15  may include an electronic component required to drive the camera module  1010 . For example, the substrate  600 - 15  may be equipped with the image sensor  610 , the passive element  640  and the like. The electronic components mounted on or embedded in the substrate  600 - 15  may be electrically connected to each other. For example, the electric circuit electrically connecting the electronic components to each other may be formed on the one surface of or in the substrate  600 - 15 . The substrate  600 - 15  may provide power and a control signal that are necessary to drive the camera module  1010 . The substrate  600 - 15  may include a first substrate  602  and a second substrate  604  to more efficiently dispose the electronic components thereon. The image sensor  610  may be disposed on the first substrate  602 , and the passive element, the connection terminal, or the like may be disposed on the second substrate  604 . However, the electronic components, disposed on the first substrate  602  and the second substrate  604 , are not limited to the above-described components. For example, the passive element may also be disposed on the first substrate  602 . The power supply terminal  640  may be connected to the heat generation device  460 . For example, the power supply device  640  may be electrically connected to the heat generation device  460  by the connection line  642 . 
     The cover member  700  may prevent separation of the first lens  110  from the lens barrel  200 - 15 . For example, the cover member  700  may secure the first lens  110  to the second lens barrel  220 - 15 . The cover member  700  may be coupled to the second lens barrel  220 - 15 . For example, the screw portion  706  which may be fastened to the second screw portion  226  of the second lens barrel  220 - 15  may be formed on an inner circumferential surface of the cover member  700 . 
     The first, second, and third airtight members  810 ,  820  and  830  may block the gap in the camera module  1010 . For example, the first airtight member  810 , the second airtight member  820 , and the third airtight member  830  may respectively be disposed between the first lens barrel  210 - 15  and the second lens barrel  220 - 15 , between the first lens  110  and the second lens barrel  220 - 15 , and between the second lens barrel  220 - 15  and the cover member  700 . In more detail, the first airtight member  810  may be disposed on an inner jaw  228  of the second lens barrel  220 - 15 , the second airtight member  820  may be disposed on the flange portion  112  of the first lens  110 , and the third airtight member  830  may be disposed on an outer jaw  229  of the second lens barrel  220 - 15 . However, the positions where the first, second, and third airtight members  810 ,  820  and  830  are disposed are not limited to the above-described portions. The airtight member  800  may be made of the material which may be elastically deformed or compressively deformed. For example, the airtight member  800  may be made of rubber, synthetic rubber, elastomer or the like. However, the airtight member  800  is not limited to the above-mentioned material. 
     The camera module  1010  may further include spacing members  250  and  252  and the filter member (IF). The spacing members  250  and  252  may respectively be disposed between the lenses and the lens barrel  200 - 15 , and between the lens barrel  200 - 15  and the energy generation unit. As an example, the first spacing member  250  may be disposed between the first lens  110  and the first lens barrel  210 - 15 . As another example, the second spacing member  252  may be disposed between the second lens barrel  220 - 15  and the first electrode  464 . The first spacing member  250  may be made of a material having low elastic deformation and low thermal conductivity. For example, the first spacing member  250  may be made of a material that may be elastically deformed or compressively deformed to be in close contact with the first lens  110  when pressed by the cover member  700 . In addition, the first spacing member  250  may be made of the material having low thermal conductivity to minimize loss of heat transferred to the first lens  110  through the first lens barrel  210 - 15 . The second spacing member  252  may be made of an insulating material. For example, the second spacing member  252  may be made of the insulating material to prevent the current supplied through the first electrode  464  from leaking through the second lens barrel  220 - 15 . 
     The camera module  1010  may capture a still image or a video by an external signal. For example, the camera module  1010  may capture the still image or video of a subject positioned in front thereof by an external driving signal of a device (e.g., vehicle) on which the camera module  1010  is mounted. However, the camera module  1010  may not be necessarily driven by the external signal. For example, the camera module  1010  may continuously or discontinuously capture the subject positioned in the front thereof by power constantly supplied from the external source. 
     The camera module  1010  may be operated to remove foreign matter adhering to the first lens  110  by the external signal or an internal signal. As an example, the camera module  1010  may selectively drive the heat generation device  460  by the external signal to remove the foreign matter adhering to the first lens  110 . As another example, when a resolution of an image obtained through the image sensor  610  has a value less than a predetermined value, the camera module  1010  may recognize that the foreign matter is adhered to the first lens  110  and then activate the heat generation device  460 . As yet another example, the camera module  1010  may always drive the heat generation device  460  to fundamentally prevent frost, moisture, a raindrop, or the like from adhering to the surface of the first lens  110 . 
     In the camera module  1010 , the thermal energy of the heat generation device  460  may not be transferred to the first lens barrel  210 , and may thus minimize the change in the performance of the optical system  100  caused by the thermal energy of the heat generation device  460 . In addition, in the camera module  1010 , the thermal energy generated by the heat generation device  460  may be rapidly transferred to the first lens  110  through the second lens barrel  220 - 15  made of the material having high thermal conductivity, and may thus rapidly remove frost, moisture, dew, a raindrop or the like, adhering to the first lens  110 . 
       FIGS. 38 through 41  illustrate a camera module, according to another embodiment. 
     Referring to  FIGS. 38 through 41 , a camera module  1011  may include the optical system  100 , a lens barrel  200 - 16 , a barrel holder  300 - 16 , the heat generation device  460 , the housing  500 - 15 , the substrate  600 - 15 , a cover member  700 - 1 , and the airtight members  810  and  820 . However, the camera module  1011  is not limited to including the above-mentioned members. 
     The optical system  100  may include one or more lenses. For example, the optical system  100  may include the first lens  110  to the fifth lens (not shown) sequentially arranged from the object side. The optical system  100  may have a predetermined angle of view. For example, the optical system  100  may have an angle of view of 120 degrees or more to simultaneously capture the image over a wide area. However, the angle of view of the optical system  100  is not limited to 120 degrees or more. For example, the optical system  100  may have an angle of view of less than 120 degrees. 
     The first lens  110  may be disposed at the forwardmost of the optical system  100 . For example, the first lens  110  may be disposed for its (object-side) surface to be partially exposed outward. The first lens  110  may have a predetermined refractive power. For example, the first lens  110  may have positive or negative refractive power. One surface of the first lens  110  may have a convex shape. As an example, the object-side surface of the first lens  110  may have a convex shape. However, the object-side surface of the first lens  110  may not necessarily have a convex shape. 
     The first lens  110  may be easily fixed by the cover member  700 - 1 . For example, the flange portion  112 , which may be coupled to the cover member  700 , may be formed on the edge of the first lens  110 . 
     The lens barrel  200 - 16  may accommodate the optical system  100 . For example, the lens barrel  200 - 16  may include the accommodation space accommodating the optical system  100 . The lens barrel  200 - 16  may accommodate the plurality of lenses. For example, the lens barrel  200 - 16  may accommodate the lenses except for the first lens  110 . 
     There may be the plurality of lens barrels  200 - 16 . For example, the lens barrel  200 - 16  may include a first lens barrel  210 - 16  and a second lens barrel  220 - 16 . The first lens barrel  210 - 16  and the second lens barrel  220 - 16  may be made of materials that are different from each other. As an example, the first lens barrel  210 - 16  may be made of a material having low thermal conductivity or a material having low electrical conductivity, and the second lens barrel  220 - 16  may be made of a material having high thermal conductivity or a material having high electrical conductivity. As another example, the first lens barrel  210 - 16  may be made of a plastic material, and the second lens barrel  220 - 16  may be made of a metal material. 
     The first lens barrel  210 - 16  may accommodate the plurality of lenses. For example, the lens barrel  210 - 16  may accommodate all the lenses including the first lens  110 . The first lens barrel  210 - 16  may be firmly coupled with another member. For example, a first screw portion  211  and the second screw portion  213  may be formed on the outer circumferential surface of the first lens barrel  210 - 16 . The first screw portion  211  may be formed on the lower portion of the first lens barrel  210 - 16 , and the second screw portion  213  may be formed on the upper portion of the first lens barrel  210 - 16 . However, the positions where the first screw portion  211  and the second screw portion  213  are formed are not limited to the lower and upper portions of the first lens barrel  210 - 16 . 
     The first screw portion  211  may allow the first lens barrel  210 - 16  and the barrel holder  300 - 16  to be coupled to each other. For example, the first screw portion  211  may be screwed with the screw portion  302  formed on the inner circumferential surface of the barrel holder  300 - 16 . However, the coupling between the first lens barrel  210 - 16  and the barrel holder  300 - 16  is not limited to a screw coupling. For example, the first lens barrel  210 - 16  and the barrel holder  300 - 16  may be coupled to each other by using the method such as the press-fit, the adhesion, the fusion or the like. The second screw portion  213  may allow the first lens barrel  210 - 16  and the cover member  700 - 1  to be coupled to each other. For example, the second screw portion  213  may be screwed with the screw portion  706  formed on the inner circumferential surface of the cover member  700 - 1 . However, the coupling between the first lens barrel  210  and the cover member  700 - 1  is not limited to screw coupling. For example, the first lens barrel  210 - 16  and the cover member  700 - 1  may be coupled to each other by using the method such as a press-fit, adhesion, fusion, or the like. 
     The first lens barrel  210  may include a component by which the first lens barrel  210 - 16  and the second lens barrel  220 - 16  are coupled to each other. For example, a coupling hole  219 , into which the extension  229  of the second lens barrel  220 - 16  is inserted, may be formed in the first lens barrel  210 - 16 . The coupling holes  219  may be spaced apart from each other in a circumferential direction of the first lens barrel  210 - 16 . The coupling hole  219  may be open outward from the inside of the first lens barrel  210 - 16 . Accordingly, the extension  229  of the second lens barrel  220 - 16 , inserted into the coupling hole  219 , may protrude or be exposed outward from the first lens barrel  210 - 16 . 
     The second lens barrel  220 - 16  may support one surface of the first lens  110 . For example, the second lens barrel  220 - 16  may support the first lens  110  for the first lens  110  to be maintained at a predetermined height from the first lens barrel  210 - 16 . The second lens barrel  220 - 16  may be in contact with the first lens  110 . For example, an upper portion  223  of the second lens barrel  220 - 16  may be in contact with a lower flange portion  112  of the first lens  110 . The second lens barrel  220  and the first lens  110  may maximize an area in which the second lens barrel  220 - 16  and the first lens  110  are in contact with each other in a range in which the contact area does not affect the optical feature of the first lens  110 . For example, a partial area of the lower portion of the first lens  110 , excluding an area EA through which effective light substantially transmits, may be in contact with the upper portion  223  of the second lens barrel  220 - 16 . Therefore, the camera module  1011  may secure a sufficient contact area between the first lens  110  and the second lens barrel  220 - 16 , and may thus rapidly and easily heat the first lens  110  or transfer energy to the first lens  110 , through the second lens barrel  220 - 16 . 
     The second lens barrel  220 - 16  may function as an energy transfer member. To this end, the second lens barrel  220 - 16  may be made of the material which may easily transfer the energy. For example, the second lens barrel  220 - 16  may be made of a material having high thermal conductivity to easily transfer the thermal energy. As a specific example, the second lens barrel  220 - 16  may be made of copper, aluminum, an alloy of copper and aluminum, or the like. However, the material of the second lens barrel  220 - 16  is not limited to copper or aluminum. For example, the second lens barrel  220 - 16  may be made of a material having high thermal conductivity, other than the metal material. 
     The second lens barrel  220 - 16  may be in contact with the heat generation device  460 , which is an energy generation unit. For example, the second lens barrel  220 - 16  may include the extension  229  in contact with the inner circumferential surface of the heat generation device  460 . The extensions  229  may each be extended downward from the body of the second lens barrel  220 - 16 , and may be spaced apart from each other in the circumferential direction of the second lens barrel  220 - 16 . The extension  229  may be inserted into the first lens barrel  210 - 16 . For example, the extension  229  may be inserted into coupling hole  219  of the first lens barrel  210 - 16 . The extension  229  may be exposed or protrude outward from the first lens barrel  210 - 16  to be in contact with another adjacent member. For example, the extension  229  may pass through the coupling hole  219  to protrude outward from the first lens barrel  210 - 16 . 
     The second lens barrel  220 - 16  may function as the spacing member. For example, the second lens barrel  220 - 16  may maintain a constant distance between the first lens  110  and the second lens (i.e., lens disposed on an image-side of the first lens). When using the second lens barrel  220 - 16  as the spacing member, the camera module  1011  may have a simple configuration. For example, when using the second lens barrel  220 - 16  as the spacing member, the camera module  1011  may omit the spacing member  250  shown in  FIG. 38 , and may transfer energy to the first lens  110  and the second lens through the second lens barrel  220 - 16 . 
     The barrel holder  300 - 16  may be coupled with the first lens barrel  210 - 16 . For example, the barrel holder  300 - 16  may be firmly coupled to the first lens barrel  210 - 16  by the screw portions  302  and  211  fastened to each other. The barrel holder  300  may be coupled with the substrate  600 - 15 . For example, the barrel holder  300 - 16  may be coupled with the substrate  600 - 15  by interposing the leg member  350  therebetween. The leg member  350  may be fixed to the substrate  600 - 15  by using a bolt  980 . The extraction hole  306  may be formed in the barrel holder  300 - 16 . The extraction hole  306  may be used as the outlet for the power line  642  that connects the power supply terminal  640  of the substrate  600 - 15  and the heat generation device  460  to each other. The barrel holder  300 - 16  may be made of a material having low energy transfer efficiency. For example, the barrel holder  300 - 16  may be made of a plastic material having low thermal conductivity. However, the barrel holder  300 - 16  is not limited to the plastic material. 
     The heat generation device  460  may be disposed on the outer circumferential surface of the first lens barrel  210 - 16 . For example, the heat generation device  460  may be disposed above the first screw portion  211  of the first lens barrel  210 - 16 . The heat generation device  460  may be in contact with the second lens barrel  220 - 16 . For example, the heat generation device  460  may be disposed to be in contact with the extension  229  of the second lens barrel  220 - 16 . The heat generation device  460  may generate thermal energy. For example, the heat generation device  460  may be a PTC heater always maintained at a constant temperature. 
     The heat generation device  460  may include the heating element  462  and the electrodes  464  and  466 . The heating element  462  may generally have the shape of a ring having one side open, and the electrodes  464  and  466  may each have a disk shape. However, the heating elements  462  and the electrodes  464  and  466  are not limited to the ring and disk shapes, respectively. The heating element  462  may be elastically deformed or its shape may be deformed. Therefore, the heating element  462  may be freely deformed to be inserted into a space where the heat generation device  460  is disposed, and may be in close contact with the second lens barrel  220 - 16 . The heating element  462  may include the component configured to convert electrical energy into the thermal energy. For example, the heating element  462  may be made of a material having high electrical resistance, or may be an electronic component including a plurality of resistance elements. The electrodes  464  and  466  may supply current to the heating element  462 . The first electrode  464  may be disposed on the top portion of the heating element  462 , and the second electrode  466  may be disposed on the bottom portion of the heating element  462 . 
     The heat generation device  460  may supply the thermal energy to the first lens  110 . For example, the thermal energy generated by the heat generation device  460  may be transferred to the first lens  110  through the second lens barrel  220 - 16  having high thermal conductivity. The heat generation device  460  may allow foreign matter adhering to the first lens  110  to be removed. For example, the thermal energy generated from the heat generation device  460  may be used as an energy source to evaporate frost, dew, moisture, and a water droplet adhering to the surface of the first lens  110 . 
     The housing  500 - 15  may accommodate the lens barrel  200 - 16 , the barrel holder  300 - 16  and the substrate  600 - 15 . For example, the housing  500 - 15  may accommodate all of the lens barrel  200 - 16 , the barrel holder  300 - 16  and the substrate  600 - 15 . The housing  500 - 15  may include the component that supports the position of the substrate  600 - 15 . For example, the support member  540 , which may be coupled to the substrate  600 - 15  while supporting the position of the substrate  600 - 15 , may be formed on the lower portion of the housing  500 - 15 . The support member  540  may support the four corners of the substrate  600 - 15  and may be coupled to the substrate  600 - 15  by the bolt  982 . The housing  500 - 15  may include the component through which the input and output cables are extracted. For example, the passage  530  through which the input and output cables are extracted may be formed on one side of the housing  500 - 15 . The housing  500 - 15  may be coupled with the cover member  700 - 1 . For example, the housing  500 - 15  may be coupled with the cover member  700 - 1  by the method such as adhesion, fitting, screwing, etc. The housing  500 - 15  may be made of a material resistant to impacts. For example, the housing  500 - 15  may be made of a metal material. However, the housing  500 - 15  is not limited to the metal material. For example, the housing  500 - 15  may be made of a plastic material to reduce the weight of the camera module  1011 . 
     The substrate  600 - 15  may include an electronic component required to drive the camera module  1011 . For example, the substrate  600 - 15  may be equipped with the image sensor  610 , the passive element  640 , and the like. The electronic components mounted on or embedded in the substrate  600 - 15  may be electrically connected to each other. For example, the electric circuit electrically connecting the electronic components to each other may be formed on the one surface of or in the substrate  600 - 15 . The substrate  600 - 15  may provide power and a control signal that are necessary to drive the camera module  1011 . The substrate  600 - 15  may include the first substrate  602  and the second substrate  604  to more efficiently dispose the electronic components thereon. The image sensor  610  may be disposed on the first substrate  602 , and the passive element, the connection terminal, or the like may be disposed on the second substrate  604 . However, the electronic components disposed on the first substrate  602  and the second substrate  604  are not limited to the above-described components. For example, the passive element may also be disposed on the first substrate  602 . The power supply terminal  640  may be connected to the heat generation device  460 . For example, the power supply device  640  may be electrically connected to the heat generation device  460  by the connection line  642 . 
     The cover member  700 - 1  may prevent the separation of the first lens  110  from the lens barrel  200 - 16 . For example, the cover member  700 - 1  may secure the first lens  110  to the first lens barrel  210 - 16 . The cover member  700 - 1  may be coupled to the first lens barrel  210 - 16 . For example, the screw portion  706 , which may be fastened to the second screw portion  213  of the first lens barrel  210 - 16 , may be formed on the inner circumferential surface of the cover member  700 - 1 . 
     The airtight members  810  and  820  may block the gap in the camera module  1011 . For example, the first airtight member  810  and the second airtight member  820  may respectively be disposed between the first lens  110  and the cover member  700 - 1 , and between barrel holder  300 - 16  and the cover member  700 - 1 . The first airtight member  810  may be disposed between the first lens  110  and the cover member  700 - 1 . The first airtight member  810  may be disposed on the edge of the first lens  110  to block foreign matter or external air from intruding into the space between the first lens  110  and the cover member  700 - 1 . The second airtight member  820  may be disposed between the barrel holder  300  and the cover member  700 - 1 . The second airtight member  820  may be disposed on the edge of the cover member  700 - 1  to block the foreign matter or the external air from intruding into the space between the barrel holder  300 - 16  and the cover member  700 - 1 . For reference, a groove  708  accommodating the second airtight member  820  may be formed on the outer circumferential surface of the cover member  700 - 1 . The airtight members  810  and  820  may each be made of the material which may be elastically deformed or compressively deformed. For example, the airtight members  810  and  820  may each be made of rubber, synthetic rubber, elastomer or the like. However, each of the airtight members  810  and  820  is not limited to the above-mentioned material. 
     The camera module  1011  according to this embodiment may further include an intermediate member  260 . For example, the camera module  1011  may further include the intermediate member  260  disposed between the extension  229  of the second lens barrel  220 - 16  and the heating element  462  of the heat generation device  460 . The intermediate member  260  may be elastically deformed or stretched and compressed. For example, intermediate member  260  may be partially expanded or partially deformed to be coupled with the extension  229 . The intermediate member  260  may be made of a material having high thermal conductivity. For example, the intermediate member  260  may be made of copper, aluminum, or an alloy of copper and aluminum. However, the material of the intermediate member  260  is not limited to the above-mentioned materials. The intermediate member  260  may increase an area in which the extension  229  and the heating element  462  are in contact with each other. For example, the intermediate member  260  may be in close contact with a surface of the extension  229 , while simultaneously being in close contact with an inner circumferential surface of the heating element  462 . Accordingly, the thermal energy generated from the heating element  462  may be transferred to the extension  229  of the second lens barrel  220  through the intermediate member  260 . 
     The camera module  1011  may increase the contact area and heat transfer area between the heat generation device  460  and the second lens barrel  220 - 16  by including the intermediate member  260 , and may thus rapidly heat the second lens barrel  220 - 16  through the heat generation device  460 . 
       FIG. 42  illustrates a camera module, according to another embodiment. 
     Referring to  FIG. 42 , a camera module  1012  may include a first lens barrel  210 - 17 , a second lens barrel  220 - 17 , an energy generation unit  400 - 17 , a first housing  510 - 1 , a second housing  520 - 1  and the cover member  700 - 2 . However, the camera module  1012  is not limited to including the above-mentioned members. 
     The first lens barrel  210 - 17  may accommodate the plurality of lenses. For example, two or more lenses  120  may be accommodated in the first accommodation portion  212  of the first lens barrel  210 - 17 . However, the number of lenses accommodated in the first lens barrel  210 - 17  is not limited to two. The first lens barrel  210 - 17  may be coupled with the second lens barrel  220 - 17  or accommodate the second lens barrel  220 - 17 . For example, the second accommodation portion  214  accommodating the second lens barrel  220 - 17  may be formed in the first lens barrel  210 - 17  separately from the first accommodation portion  212 . 
     The second lens barrel  220 - 17  may be coupled with the first lens barrel  210 - 17 . For example, the second lens barrel  220 - 17  may be disposed inside the first lens barrel  210 - 17 . The second lens barrel  220 - 17  may be easily coupled with the first lens barrel  210 - 17 . For example, the second lens barrel  220 - 17  may include the extension  229  inserted into the second accommodation portion  214 . The second lens barrel  220 - 17  may accommodate a forwardmost lens  110 - 1  or be in contact with the forwardmost lens  110 . The second lens barrel  220 - 17  may be significantly sized to be in contact with the forwardmost lens  110 - 1 . For example, one surface of the second lens barrel  220 - 17  may be in contact with a flange portion  113  of the forwardmost lens  110 - 1 . The second lens barrel  220 - 17  may maintain a constant distance between the forwardmost lens  110 - 1  and the lens  120 . For example, the second lens barrel  220 - 17  may include a protrusion  226   a  protruding toward the first accommodation portion  212  of the first lens barrel  210 - 17 . The protrusion  226   a  may be formed between the forwardmost lens  110 - 1  and the lens  120  to maintain the constant distance between the forwardmost lens  110 - 1  and the lens  120 . The second lens barrel  220 - 17  may be made of a material having higher thermal conductivity than that of the first lens barrel  210 - 17 . In more detail, the second lens barrel  220 - 17  may be made of a metal material which may easily transfer heat. However, the material of the second lens barrel  220 - 17  is not limited to the metal. 
     The energy generation unit  400 - 17  may generate a predetermined amount of energy. For example, the energy generation unit  400 - 17  may be a heat generation device configured to generate thermal energy. As an example, the energy generation unit  400 - 17  may be a positive temperature coefficient (PTC) heater. However, the energy generation unit  400 - 17  is not limited to the heat generation device. For example, the energy generation unit  400 - 17  may be the excitation device or piezoelectric body configured to generate vibration energy. The energy generation unit  400 - 17  may be in close contact with the second lens barrel  220 - 17 . For example, the energy generation unit  400 - 17  may be disposed in the second accommodation portion  214  of the first lens barrel  210  to be in contact with the extension  229  of the second lens barrel  220 - 17 . 
     The energy generation unit  400 - 17  may transfer energy to the second lens barrel  220 - 17  and the forwardmost lens  110 - 1  in contact with the second lens barrel  220 - 17 . For example, the energy generated by the energy generation unit  400 - 17  may be transferred to the body of the second lens barrel  220 - 17  and the forwardmost lens  110 - 1  through the extension  229 . The energy generated by the energy generation unit  400 - 17  may be generally transferred only to the second lens barrel  220 - 17 . For example, the second lens barrel  220 - 17  may be made of a material which may receive thermal energy, vibration energy and the like more easily than that of the first lens barrel  210 - 17 , and most of the energy generated by the energy generation unit  400 - 17  may thus be transferred to the second lens barrel  220 - 17  or absorbed into the second lens barrel  220 - 17 . 
     The energy generated by the energy generation unit  400 - 17  may be used to remove foreign matter adhering to the surface of the forwardmost lens  110 - 1 . As an example, frost, moisture, or the like adhered to the surface of the forwardmost lens  110 - 1  may be removed by the thermal energy transferred from the energy generation unit  400 - 17 . As another example, dust or the like adhered to the surface of the forwardmost lens  110 - 1  may be separated therefrom by vibration energy transferred from the energy generation unit  400 - 17 . 
     For reference, the power line  642  connecting the energy generation unit  400 - 17  and the external power source may be extracted outward from the first lens barrel  210 - 17  through a hole  217  formed in the second accommodation portion  214  of the first lens barrel  210 - 17 . 
     A housing  500 - 17  including the first housing  510 - 1  and the second housing  520 - 1  may accommodate some components of the camera module  1012 . For example, an electronic component required to drive the camera module  1012  may be disposed or accommodated in a space  502  formed by the coupling of the first housing  510 - 1  and the second housing  520 - 1 . The housing  500 - 17  may fix the position of the first lens barrel  210 - 17 . For example, the first housing  510 - 1  may be coupled to the first lens barrel  210 - 17  to fix the position of the first lens barrel  210 - 17 . 
     The cover member  700 - 2  may secure the forwardmost lens  110 - 1  to the first lens barrel  210 - 17 . For example, the cover member  700 - 2  may be coupled to the first lens barrel  210 - 17  while pressing the edge of the forwardmost lens  110 - 1 . The cover member  700 - 2  may be coupled to the first lens barrel  210 - 17  by a screw coupling. 
     As set forth above, according to embodiments disclosed herein, it is possible to resolve resolution degradation due to foreign matter. It is also possible to resolve the problem of a field of view being blocked due to the foreign matter. 
     While this disclosure includes specific examples, it will be apparent after an understanding of the disclosure of this application that various changes in form and details may be made in these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be considered in a descriptive sense only, and not for purposes of limitation. Descriptions of features or aspects in each example are to be considered as being applicable to similar features or aspects in other examples. Suitable results may be achieved if the described techniques are performed in a different order, and/or if components in a described system, architecture, device, or circuit are combined in a different manner, and/or replaced or supplemented by other components or their equivalents. Therefore, the scope of the disclosure is defined not by the detailed description, but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents are to be construed as being included in the disclosure.