Abstract:
Provided is a headlamp of a vehicle, and more particularly, an automotive headlamp which is structured in a simple manner to secure a sufficient amount of light, emit light in different beam patterns, and improve heat dissipation efficiency thereof. The automotive headlamp includes: a plurality of lamp modules disposed in different directions from an optical axis of the automotive headlamp; and a projection lens projecting light emitted from one or more of the lamp modules. Each of the lamp modules includes a light source unit emitting light downward, and a reflector disposed under the light source unit and reflecting light emitted from the light source unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from Korean Patent Application No. 10-2011-0112376 filed on Oct. 31, 2011 and 10-2012-0106615 filed on Sep. 25, 2012, which applications are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a headlamp of a vehicle, and more particularly, to an automotive headlamp which is structured in a simple manner to secure a sufficient amount of light, emit light in different/various beam patterns, and improve heat dissipation efficiency. 
     2. Description of the Related Art 
     Vehicles are typically equipped with various automotive lamps having a lighting function and a signaling function, among others. That is, automotive lamps enable the driver of the vehicle to easily detect objects around and ahead of the vehicle while driving at night or in a dark area. They also inform other vehicles and road users of the vehicle&#39;s driving state. For example, a headlamp and a fog lamp are designed for providing light, and a direction indicator, a taillight, a brake light, and a side marker are designed for signaling. 
     Recently, many automotive lamp manufactures have begun to use halogen lamps or high-intensity discharge (HID) lamps as light sources. Additionally, light-emitting diodes (LEDs) have been used as light sources as well. LEDs have a color temperature of approximately 5500 K which is close to that of sunlight. Thus, LEDs cause the least eye fatigue. In addition, LEDs increase the freedom of lamp design due to their small size and are economical due to their semi-permanent lifespan. 
     LEDs, in particular, are being introduced to reduce lamp configuration complications and decrease the number of manufacturing processes required to produce a headlamp. In particular, attempts are being made to extend lamp life using characteristics of LEDs. Furthermore, since limited space is not an issue due to the small size of the LEDs, they may be utilized in a plethora of applications. 
     Of the various types of automotive lamps, a headlamps use more than one beam pattern unlike other types of lamps which typically use only one. For example, the headlamp may emit light in a beam pattern optimum for driving conditions of the vehicle such as travelling speed, travelling direction, road surface conditions, and ambient brightness. In so doing, the headlamp may ensure driver visibility without blinding other vehicle drivers on the road. Generally, one or more LEDs are used to emit light in each beam pattern while securing a sufficient amount of light. However, to emit light in different beam patterns, elements corresponding to each beam pattern are required. Accordingly, this increases the number of parts, costs and space required. In addition, when LEDs are used as light sources of automotive lamps, the light emission efficiency of the LEDs rapidly deteriorate as the temperature rises. 
     Therefore, a solution that can emit light in various beam patterns, secure a sufficient amount of light, and prevent a temperature rise due to heat emitted from LEDs while reducing the number of parts, costs and space required to emit light in different beam patterns is required. 
     SUMMARY OF THE INVENTION 
     Aspects of the present invention provide an automotive headlamp in which a plurality of lamp modules, which use light-emitting diodes (LEDs) for emitting light in different beam patterns as light sources, are placed in different directions from an optical axis of the automotive headlamp to minimize the space required and emit light in various beam patterns and in which a lamp module for emitting light in a predetermined beam pattern consists of a plurality of lamp modules to secure a sufficient amount of light. 
     Aspects of the present invention also provide an automotive headlamp in which heat sinks are installed to efficiently prevent a temperature rise due to heat emitted from LEDs. 
     However, aspects of the present invention are not restricted to the one set forth herein. The above and other aspects of the present invention will become more apparent to one of ordinary skill in the art to which the present invention pertains by referencing the detailed description of the present invention given below. 
     According to an aspect of the present invention, there is provided an automotive headlamp including: a plurality of lamp modules disposed in different directions from an optical axis of the automotive headlamp; and a projection lens projecting light emitted from one or more of the lamp modules, wherein each of the lamp modules includes: a light source unit emitting light downward; and a reflector disposed under the light source unit and reflecting light emitted from the light source unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects and features of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which: 
         FIG. 1  is a perspective view of an automotive headlamp according to a first exemplary embodiment of the present invention; 
         FIG. 2  is a schematic front view of a first lamp module and a second lamp module according to the first exemplary embodiment of the present invention; 
         FIG. 3  is a perspective view of an automotive headlamp according to a second exemplary embodiment of the present invention; 
         FIG. 4  is a schematic front view of a first lamp module and a second lamp module according to the second exemplary embodiment of the present invention; 
         FIG. 5  is a schematic diagram illustrating the direction in which light travels in the automotive headlamp of  FIGS. 1 and 2 ; 
         FIGS. 6 and 7  are schematic views of heat sinks according to the first exemplary embodiment of the present invention; 
         FIG. 8  is a schematic view of heat pads according to an exemplary embodiment of the present invention; 
         FIG. 9  is a schematic view of heat sinks according to the second exemplary embodiment of the present invention; 
         FIGS. 10 and 11  are perspective views of an assembled automotive headlamp according to an exemplary embodiment of the present invention; 
         FIG. 12  is a plan view of the assembled automotive headlamp shown in  FIGS. 10 and 11 ; and 
         FIG. 13  is a base view of the assembled automotive headlamp shown in  FIGS. 10 and 11 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Advantages and features of the present invention and methods of accomplishing the same may be understood more readily by reference to the following detailed description of exemplary embodiments and the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the invention to those skilled in the art, and the present invention will only be defined by the appended claims. Like reference numerals refer to like elements throughout the specification. 
     In some embodiments, well-known manufacturing processes, well-known structures and well-known technologies will not be specifically described in order to avoid ambiguous interpretation of the present invention. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated elements, steps, and/or operations, but do not preclude the presence or addition of one or more other elements, steps, operations, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Embodiments of the invention are described herein with reference to perspective, cross-sectional, side, and/or schematic illustrations that are illustrations of idealized embodiments of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the invention should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. In the drawings, each element may be exaggerated or reduced for clarity. 
     Automotive headlamps according to embodiments of the present invention will now be described with reference to the attached drawings. 
       FIG. 1  is a perspective view of an automotive headlamp  1  according to a first exemplary embodiment of the present invention.  FIG. 2  is a schematic front view of a first lamp module  100  and a second lamp module  200  according to the first exemplary embodiment of the present invention. 
     Referring to  FIGS. 1 and 2 , the automotive headlamp  1  according to the first exemplary embodiment may include the first lamp module  100 , the second lamp module  200 , a shield  300 , and a projection lens  400 . In the first embodiment of the present invention, the first lamp module  100  and the second lamp module  200  are disposed in different directions from an optical axis C of the projection lens  400  and used/configured to emit light in different beam patterns. In the first embodiment of the present invention, the first lamp module  100  may be disposed above the optical axis C and used to emit light in a low-beam pattern, and the second lamp module  200  may be disposed below the optical axis C and used to emit light in a high-beam pattern. 
     In addition, the first lamp module  100  and the second lamp module  200  are used in the first embodiment of the present invention. However, the present invention is not limited thereto, and a lamp module can be added or removed according to beam patterns used. 
     The first lamp module  100  may include a first light source unit  110  which emits light downward and a first reflector  120  which reflects light emitted from the first light source unit  110  so that the light is directed toward a lower part of the projection lens  400 . The first light source unit  110  may include a light source  111  and a substrate  112  on which the light source  111  is installed. The light source  111  may be installed on a bottom surface of the substrate  112  to emit light downward. The first reflector  120  may be disposed under the first light source unit  110  to reflect light emitted from the first light source unit  110  and may be shaped in the form of an oval or free curved surface having an open surface. 
     The second lamp module  200  may include a second light source  201  which emits light downward and a second reflector  202  which reflects light emitted from the second light source  201  such that the light travels toward an upper part of the projection lens  400 . Like the first light source unit  110 , the second light source unit  201  may include a light source  201   a  and a substrate  201   b  on which the light source  201   a  is installed. The light source  201   a  may be installed on a bottom surface of the substrate  201   b  to emit light downward. Also like the first reflector  120 , the second reflector  202  may be disposed under the second light source unit  201  to reflect light emitted from the second light source unit  201  and may be shaped like an oval or free curved surface having an open surface. 
     In the first embodiment of the present invention, the light source  111  of the first light source unit  110  and the light source  201   a  of the second light source unit  201  may be, but are not limited to, light-emitting diodes (LEDs). In addition, the first reflector  120  and the second reflector  202  may be physically connected to each other or separated from each other. When the first reflector  120  and the second reflector  202  are disposed under the first light source unit  110  and the second light source unit  201 , respectively, the entire first reflector  120  and the entire second reflector  202  may be disposed under the first light source unit  110  and the second light source unit  201 , respectively, or part of the first reflector  120  and part of the second reflector  202  may be disposed under the first light source unit  110  and the second light source unit  201 , respectively. 
     In the first embodiment of the present invention, light emitted from the first lamp module  100  may travel toward the lower part of the projection lens  400 , and light emitted from the second lamp module  200  may travel toward the upper part of the projection lens  400 . To this end, the first reflector  120  may reflect the light emitted from the first lamp module  100  toward the lower part of the projection lens  400 , and the second reflector  202  may reflect the light emitted from the second lamp module  200  toward the upper part of the projection lens  400 . In addition, each of the first lamp module  100  and the second lamp module  200  may be placed at a predetermined angle to the optical axis C. 
     The shield  300  may be disposed in front of the first lamp module  100  and the second lamp module  200 . The shield  300  may form a predetermined cut-off line by blocking part of light emitted from one or more of the first lamp module  100  and the second lamp module  200 . The shield  300  may be shaped like a plate having a semicircular groove  310  at a side thereof. The shape of the groove  310  can vary, however, and is not limited to the illustrative embodiment of the present invention. 
     In the first exemplary embodiment of the present invention, the shield  300  may block or reflect part of light emitted from the first lamp module  100  in order to project the light in the low-beam pattern. To reflect part of light, a surface of the shield  300  may be coated with a reflective layer. 
     In  FIGS. 1 and 2  described above, one lamp module is disposed above and below the optical axis C. However, this is merely an example used to help understand the present invention, and the present invention is not limited to this example. One or more of the first lamp module  100  and the second lamp module  200  may also consist of a plurality of lamp modules arranged in a particular direction. 
       FIG. 3  is a perspective view of an automotive headlamp  1  according to a second exemplary embodiment of the present invention.  FIG. 4  is a schematic front view of a first lamp module  100  and a second lamp module  200  according to the second embodiment of the present invention. In  FIGS. 3 and 4 , the second lamp module  200  consists of a plurality of lamp modules. Referring to  FIGS. 3 and 4 , unlike the above-described automotive headlamp  1  of  FIGS. 1 and 2 , the automotive headlamp  1  according to the second embodiment of the present invention may include the second lamp module  200  which consists of a lamp module  210  and a lamp module  220  respectively disposed on both sides of an optical axis C. In the second embodiment of the present invention, the second lamp module  200  consists of two lamp modules. However, the number of lamp modules that constitute the second lamp module  200  can vary, and thus should not be limited hereto. 
     The first lamp module  100 , a shield  300 , and a projection lens  400  of  FIGS. 3 and 4  are identical to those described above with reference to  FIGS. 1 and 2 , and thus a detailed description thereof will be omitted. 
     In the second embodiment of the present invention, the lamp module  210  and the lamp module  220  are respectively disposed on both sides of the optical axis C in an orientation which is horizontal to each other. However, the present invention is not limited thereto. 
     The lamp module  210  may include a light source unit  211  and a reflector  212 , and the lamp module  220  may include a light source unit  221  and a reflector  222 . The light source unit  211  and the light source unit  221  may include light sources  211   a  and  221   a  and substrates  211   b  and  221   b  on which the light sources  211   a  and  221   a  are installed, respectively. The light sources  211   a  and  221   a  may be disposed on bottom surfaces of the substrates  211   b  and  221   b  to emit light downward. 
     As in  FIGS. 1 and 2 , in  FIGS. 3 and 4 , the light source  211   a  of the light source unit  211  and the light source  221   a  of the light source unit  221  may be LEDs. The reflector  212  may be disposed under the light source unit  211  to reflect light emitted from the light source unit  211 , and the reflector  222  may be disposed under the light source unit  221  to reflect light emitted from the light source unit  221 . If the reflector  212  and the reflector  222  are disposed under the light source unit  211  and the light source unit  221 , respectively, the whole of the reflector  212  and the whole of the reflector  222  may be disposed under the light source unit  211  and the light source unit  221 , respectively, or part of the reflector  212  and part of the reflector  222  may be disposed under the light source unit  211  and the light source unit  221 , respectively. 
     The reflector  212  and the reflector  222  may be physically connected to each other or independently attached. The light source unit  211  and the light source unit  221  may be situated at first focal points of the reflector  212  and the reflector  222 , respectively. The reflector  212  and the reflector  222  may have identical or different second focal points behind the projection lens  400 . If the second lamp module  200  consists of a plurality of lamp modules arranged in a particular direction as described above, a sufficient amount of light can be secured with relatively low power consumption. 
       FIG. 5  is a schematic diagram illustrating the direction in which light travels in the automotive headlamp  1  of  FIGS. 1 and 2 . The principle illustrated in  FIG. 5  can also apply to the automotive headlamp  1  of  FIGS. 3 and 4 . Referring to  FIG. 5 , the first lamp module  100  may be disposed above the optical axis C, and the second lamp module  200  may be disposed below the optical axis C. The shield  300  may be disposed in front of the first lamp module  100  and the second lamp module  200 . 
     The first light source unit  110  of the first lamp module  100  and the second light source unit  201  of the second lamp module  200  emit light downward. The light emitted from the first light source unit  110  and the light emitted from the second light source unit  201  may be reflected respectively by the first reflector  120  and the second reflector  202  to reach the projection lens  400  via the shield  300 , as indicated by arrows in  FIG. 5 . 
     In  FIG. 5 , light is passing through the groove  310  of the shield  300  to reach the projection lens  400  is illustrated as an example. However, the present invention is not limited to this case. Part of the light can also be blocked or reflected by a surface of the shield  300  which does not have the groove  310 . 
     In the above-described embodiments of the present invention, LEDs are used as light sources. However, since LEDs are vulnerable to heat, their performance may deteriorate when the LEDs are exposed to heat. Therefore, heat sinks may be used to prevent a temperature increase due to heat emitted from the LEDs. 
       FIGS. 6 and 7  are schematic views of heat sinks  500  installed on lamp modules according to the first exemplary embodiment of the present invention. In  FIGS. 6 and 7 , an example heat sink  500  installed on each lamp module of the automotive headlamp  1  of  FIGS. 1 and 2  is illustrated. Referring to  FIGS. 6 and 7 , the first lamp module  100  and the second lamp module  200  may be disposed above and below the optical axis C of the projection lens  400 . In this case, the heat sinks  500  may be installed on the first lamp module  100  and the second lamp module  200 , respectively. 
     Specifically, in the first embodiment of the present invention, the first reflector  120  is disposed under the first light source unit  110  in the first lamp module  100 , and the second reflector  202  is disposed under the second light source unit  201  in the second lamp module  200 . Therefore, the heat sinks  500  may be installed on the first light source unit  110  and the second light source unit  201 , respectively. That is, the heat sinks  500  may be installed on a top surface of the substrate  112  of the first light source unit  110  and a top surface of the substrate  201   b  of the second light source unit  201 , respectively. 
     Each substrate  112  of the first light source unit  110  and substrate  201   b  of the second light source unit  201  may extend in one direction along the length of a corresponding heat sink  500 . For this reason, a relatively large-sized heat sink  500  can be installed. In addition, the shape of the substrate  112  of the first light source unit  110  and the shape of the substrate  201   b  of the second light source unit  201  can vary according to the shape of a corresponding heat sink  500 . 
     In  FIGS. 6 and 7 , the heat sinks  500  are installed on the first light source unit  110  and the second light source unit  201  in order to efficiently dissipate heat. That is, since heat is concentrated in upper parts of the first lamp module  100  and the second lamp module  200  due to natural convection, the heat sinks  500  may be installed on the first light source unit  110  and the second light source unit  201 , respectively. Heat pads  510  may also be formed between the substrates  112  and  201   b  and the heat sinks  500  as shown in  FIG. 8  to make contact surfaces between the substrates  112  and  201   b  and the heat sinks  500  level and increase heat transfer efficiency accordingly. 
     In the first exemplary embodiment of the present invention, each of the heat sinks  500  includes a plurality of heat dissipating pins which extend upward from above a corresponding light source unit  110  or  201 . However, this is merely an example used to help understand the present invention, and the present invention is not limited to this example. Each of the heat sinks  500  may also be a heat pipe or a heat spreader. For example, a side of the heat spreader may be bent in order to increase heat transfer area. 
       FIG. 9  is a schematic view of heat sinks  500  installed on lamp modules according to the second embodiment of the present invention. In  FIG. 9 , an example heat sink  500  installed on each lamp module of the automotive headlamp  1  of  FIGS. 3 and 4  is illustrated. Referring to  FIG. 9 , the first lamp module  100  may be installed above the optical axis C of the projection lens  400 , and the lamp module  210  and the lamp module  220  that constitute the second lamp module  200  may be disposed below the optical axis C to be horizontal to each other. In this case, the heat sinks  500  may be disposed on the lamp modules  100 ,  210 , and  220 , respectively. 
     Specifically, in the second embodiment of the present invention, the first reflector  120  is disposed under the first light source unit  110  in the first lamp module  100 , and the reflector  212  and the reflector  222  are disposed under the light source unit  211  and the light source unit  221  in the lamp module  210  and the lamp module  220 , respectively. Therefore, the heat sinks  500  may be disposed on the first light source unit  110 , the light source unit  211  and the light source unit  221 , respectively. That is, the heat sinks  500  may be installed on a top surface of the substrate  112  of the first light source unit  110  and top surfaces of the substrates  211   b  and  221   b  of the light source unit  211  and the light source unit  221 , respectively. 
     In the second exemplary embodiment of the present invention, a single heat sink  500  may extend over the top surfaces of the light source unit  211  and the light source unit  221 . However, the present invention is not limited thereto. Separate heat sinks  500  can also be installed on the top surfaces of the substrates  211   b  and  221   b  of the light source unit  211  and the light source unit  221 , respectively. 
     The substrate  112  of the first light source unit  110  and the substrates  211   b  and  221   b  of the light source unit  211  and the light source unit  221  may extend in one direction along the length of a corresponding heat sink  500 . For this reason, a relatively large-sized heat sink  500  can be installed. In addition, the shape of the substrate  112  of the first light source unit  110  and the shapes of the substrates  211   b  and  221   b  of the light source unit  211  and the light source unit  221  can vary according to the shape of a corresponding heat sink  500 . 
     In  FIG. 9 , the heat sink  500  is installed on each light source unit  110 ,  211  or  221  to provide efficient heat dissipation. That is, since heat is concentrated in an upper part of each lamp module  100 ,  210  or  220  due to natural convection, the heat sink  500  may be installed on each light source unit  110 ,  211  or  221  accordingly to dissipate this heat. Although not shown in  FIG. 9 , heat pads may also be formed between the substrates  112 ,  211   b  and  221   b  and the heat sinks  500  as shown in  FIG. 8  to make contact surfaces between the substrates  112 ,  211   b  and  221   b  and the heat sinks  500  level and increase heat transfer efficiency. 
       FIGS. 10 and 11  are perspective views of an assembled automotive headlamp  1  according to an embodiment of the present invention.  FIG. 12  is a plan view of the assembled automotive headlamp  1  shown in  FIGS. 10 and 11 .  FIG. 13  is a base view of the assembled automotive headlamp  1  shown in  FIGS. 10 and 11 . In  FIGS. 10 through 13 , the assembled structure of the automotive headlamp  1  of  FIGS. 3 ,  4  and  9  is illustrated as an example. The same structure may also apply to the automotive headlamp  1  of  FIGS. 1 and 2 . For simplicity, reference numerals for some elements are omitted. However, elements substantially identical to those of  FIGS. 3 ,  4  and  9  are indicated by like reference numerals. 
     Referring to  FIGS. 10 through 13 , in the automotive headlamp  1  according to the current embodiment, a first lamp module  100  may be installed above an optical axis C of a projection lens  400 , and a second lamp module  200  may be installed below the optical axis C. In addition, a lamp module  210  and a lamp module  220  of a second lamp module  200  may be disposed in a horizontal orientation to each other. 
     In the first lamp module  100 , a first light source unit  110  may be formed on a bottom surface of a heat sink  500 , and a first reflector  120  may be coupled to the heat sink  500  by first coupling members  710  (e.g., first set of screws). In addition, in the lamp module  210  and the lamp module  220 , a light source unit  211  and a light source unit  221  may be formed on a bottom surface of a heat sink  500 , and a reflector  212  and a reflector  222  may be coupled to the heat sink  500  by second coupling members  720  (e.g., a second set of screws). 
     In addition, at least one of the heat sinks  500  installed on the first lamp module  100 , the lamp module  210  and the lamp module  220  may be integrally connected to a lens holder  410  which supports the projection lens  400  by connecting portions  600 . In the current embodiment of the present invention, the heat sink  500  installed on the lamp module  210  and the lamp module  220  may be connected to the lens holder  410  by the connecting portions  600 . In the current embodiment of the present invention, the lens holder  410  is connected to at least one of the heat sinks  500  installed on the first lamp module  100 , the lamp module  210  and the lamp module  220 . However, the present invention is not limited thereto. The lens holder  410  can also be connected to any one of the elements included in each lamp module  100 ,  210  or  220 . 
     A shield  300  may include an extension portion  320  formed by extending a front end of the shield  300  located near a focus behind the projection lens  400  backward. In the exemplary embodiment of the present invention, the extension portion  320  may be mounted on the connecting portions  600 . In addition, the front end of the shield  300  may be curved so that it is gradually displaced toward both sides of the projection lens  400  along a focal plane behind the projection lens  400 . 
     Coupling portions  130  may be formed on one side of the heat sink  500  installed on the first lamp module  100  and may be coupled to a surface of the extension portion  320  which extends backward from the shield  300 . Coupling members  131  (e.g., a third set of screws) may be inserted into the coupling portions  130 , thereby coupling the coupling portions  130 , the extension portion  320  and the connecting portions  600  to each other. In the embodiment of the present invention, the extension portion  320  and the coupling portions  130  are flat plate-shaped portions, and a surface of the extension portion  320  is coupled to respective surfaces of the coupling portions  130  by the coupling members  131 . However, the present invention is not limited thereto, and the extension portion  320  and the coupling portions  130  can also be coupled to each other using various coupling methods such as hook coupling and sliding coupling. 
     In the current embodiment of the present invention, the heat sink  500  installed on the first lamp module  100  is coupled to a surface of the extension portion  320 . However, this is merely an example used to help understand the present invention, and the present invention is not limited to this example. At least one of the heat sinks  500  formed on the first lamp module  100  and the lamp module  210  and the lamp module  220  may be coupled to a surface of the extension portion  320  of the shield  300  according to the position or direction of the extension portion  320  which extends from the shield  300 . 
     Advantageously, the above described lamp modules which use LEDs as light sources are placed in different directions from an optical axis of the headlamp, and the other elements are placed so that they can be shared by the lamp modules. Therefore, the space required can be minimized while light can be emitted in various beam patterns. In addition, since a plurality of lamp modules are installed in a predetermined direction from the optical axis of the headlamp, a sufficient amount of light can be secured. Furthermore, heat sinks may be installed on light source units to efficiently prevent a temperature increases due to heat emitted from the LEDs. 
     However, the effects of the present invention are not restricted to the one set forth herein. The above and other effects of the present invention will become more apparent to one of daily skill in the art to which the present invention pertains by referencing the claims. 
     While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. The exemplary embodiments should be considered in a descriptive sense only and not for purposes of limitation. The scope of the present invention is defined by the following claims, rather than by the above-described detailed description. The meanings and scope of the claims, and all modifications or modified shapes, which are derived from equivalent concepts thereof, should be understood as being included in the scope of the present invention.