Patent Publication Number: US-2016246029-A1

Title: Actuator and camera module including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims the benefit under 35 USC 119(a) of Korean Patent Application No. 10-2015-0025962 filed on Feb. 24, 2015, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference for all purposes. 
     BACKGROUND 
     1. Field 
     The present disclosure relates to an actuator and a camera module including the same. 
     2. Description of Related Art 
     In general, a digital camera captures an image using an image sensor such as a charge coupled device (CCD) and a complementary metal-oxide semiconductor (CMOS) instead of film. A camera module for image capture has been used in various fields such as cameras for mobile devices with photographing functions, tablet personal computers (PC), and monitors or surveillance cameras installed in vehicles due to compact size and excellent performance. In particular, a camera module used in mobile devices has been gradually multi-functionalized, miniaturized, and lightened, in accordance with current trends. 
     A recent camera module used in mobile devices has auto focus and optical image stabilization (OIS), and devices included in a camera module are also required to meet miniaturization requirements by virtue of miniaturization of a lens and an increase in optical performance. Various examples of an actuator driving a camera module include voice coil motors (VCMs), step motors, piezoelectric actuators, micro electro mechanical systems (MEMS), and so on. 
     A voice coil motor (VCM) actuator used as an actuator of a camera module uses Lorentz force, that is, electromagnetic force generated between an electric field and a magnetic field. 
     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 an actuator with a simplified structure in which a terminal portion of a flexible printed circuit board (PCB) may be prevented from being damaged by having a simple structure, without a structural change of the flexible PCB. 
     In another general aspect, an actuator and camera module having a carrier accommodating a lens portion; a magnet disposed on an outer circumferential surface of the carrier; a housing comprising an opening formed in an upper surface of the housing wherein lateral surfaces of the carrier and the magnet are disposed within the housing; a coil portion disposed on a lateral surface of the housing configured to face the magnet; a flexible printed circuit board comprising a terminal portion, formed on one surface of the flexible printed circuit board, configured to supply power to the coil portion, wherein the flexible printed circuit board is coupled to the housing; and a reinforcing portion protruding from a lower surface of the housing to support a rear surface of the terminal portion. 
     In another general aspect, an actuator includes a flexible printed circuit board on which a terminal portion for supplying power to a coil portion is formed, and a reinforcing portion for limiting deformation of the terminal portion of the flexible printed circuit board, and a camera module may include the actuator described above. 
     Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an exploded perspective view of an example of an actuator; 
         FIG. 2  is a perspective view of the actuator illustrated in  FIG. 1 ; 
         FIG. 3  is a perspective view illustrating a lower surface of the actuator illustrated in  FIG. 2 ; 
         FIG. 4  is a diagram illustrating an example of a detailed structure of a flexible printed circuit board illustrated in  FIG. 1 ; and 
         FIG. 5  is an exploded perspective view of an example of a camera module. 
     
    
    
     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 to one of ordinary skill in the art. 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 to one of ordinary skill in the art, with the exception of operations necessarily occurring in a certain order. Also, descriptions of functions and constructions that are well known to one of ordinary skill 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 so that this disclosure will be thorough and complete, and will convey the full scope of the disclosure to one of ordinary skill in the art. 
     Words describing relative spatial relationships, such as “below”, “beneath”, “under”, “lower”, “bottom”, “above”, “over”, “upper”, “top”, “left”, and “right”, may be used to conveniently describe spatial relationships of one device or elements with other devices or elements. Such words are to be interpreted as encompassing a device oriented as illustrated in the drawings, and in other orientations in use or operation. For example, an example in which a device includes a second element disposed above a first element based on the orientation of the device illustrated in the drawings also encompasses the device when the device is flipped upside down in use or operation, 
     Referring to  FIG. 1 , the actuator  100  includes a carrier  110 , a magnet  120 , a housing  130 , a coil portion  140 , a flexible printed circuit board  150 , and a reinforcing portion  160 . The carrier  110  includes a hollow portion  112  to accommodate a lens portion  210  (see  FIG. 5 ). The carrier  110  and the lens portion  210  move together along an optical-axis of the lens portion. Corresponding screw threads may be formed on an inner circumferential surface of the carrier  110  and an outer circumferential surface of the lens portion  210 , respectively, and thus the lens portion may be screwed to the carrier  110 . Alternatively, the lens portion may be inserted into and otherwise fixed to the hollow portion  112  formed in the carrier  110 . In addition, the outer circumferential surface of the lens portion may be formed with a step, and the inner circumferential surface of the carrier  110  may be formed with a step corresponding to the outer circumferential surface of the lens portion so that the lens portion may be fixedly assembled with the carrier  110 . As illustrated in  FIG. 1 , the inner circumferential surface of the carrier  110  may have a cylindrical shape, and an outer circumferential surface of the carrier  110  may have a cylindrical shape. However, the inner circumferential surface of the carrier  110  and the outer circumferential surface of the carrier  110  are not limited to this shape, and thus the outer circumferential surface of the carrier  110  may have a rectangular shape or may have a rectangular shape with four edges inclined with respect to two adjacent sides. 
     The magnet  120  is disposed on and fixed to the outer circumferential surface of the carrier  110 . The magnet  120  generates a magnetic field to provide a driving force to drive the lens portion  210 . The magnet  120  is configured to move in the optical-axis direction of the lens portion together with the carrier  110 . 
     Although  FIG. 1  illustrates the a single magnet  120  disposed on the outer circumferential surface of the carrier  110 , a plurality of magnets  120  may be arranged at a plurality of outer circumferential surface areas of the carrier  110 , respectively. In addition, an area of the outer circumferential surface on which the magnet  120  is disposed may be flat to increase a contact area with the magnet  120  to enhance coupling force. For instance, the carrier  110  includes a reinforcing member  114  formed on a portion of the outer circumferential surface of the carrier  110 . The reinforcing member has a flat surface for receiving the magnet  120 . 
     The housing  130  may include an open portion, or cavity,  131  to insert and accommodate the carrier  110 , which holds the lens portion  210  and magnet, from an upper surface of the housing  130 . For instance, the housing  130  has an inner space configured to accommodate the carrier  110  and the magnet  120 . In addition, the open portion  131  corresponding to the carrier  110  formed in the upper surface of the housing  130  so that light is incident on the lens portion  210  within the carrier, and a lower open portion  132  is formed in a lower surface of the housing  130  so that light passing through the lens portion  210  reaches an image sensor  291  (refer to  FIG. 5 ) to be described later. 
     The housing  130  is configured to allow the carrier  110 , lens portion  210  and magnet  120  to move along the optical axis O, while lateral surfaces of the housing  130  support a partial lower surface of the carrier  110  and magnet  120 . 
     For instance, the lower open portion  132  corresponding to the hollow portion  112  of the carrier  110  is formed in a portion of the lower surface of the housing  130 , and a lower support surface extending toward an internal side of the housing  130  from an external side may be formed on the remaining region to support the carrier  110  and the magnet  120 . 
     The coil portion  140  is disposed on a lateral surface of the housing  130  to face the magnet  120  accommodated in the inner space of the housing  130 . For instance, the coil portion  140  may face the magnet  120  across the lateral surface of the housing  130 . The magnet  120  may be disposed on an inner lateral surface of the housing  130 , and the coil portion  140  may be disposed on an outer lateral surface of the housing  130 . By disposing the magnet  120  adjacent to the coil portion  140 , the coil portion  140  may be positioned along a magnetic field formed by the magnet  120 . When power is supplied to the coil portion  140 , the coil portion  140  generates a magnetic field that interacts with a magnetic field of the magnet  120  to generate a driving force for driving the carrier  110  and lens portion  210 . Although  FIG. 1  illustrates a single coil portion  140  disposed adjacent to a single magnet  120 , a plurality of magnets  120  may be disposed on the outer circumferential surface areas of the carrier  110 , respectively. A plurality of coil portions  140  may be arranged at the lateral surface of the housing  130  to respectively face each of the plurality magnets  120 . 
     The flexible printed circuit board  150  includes a terminal portion  152  formed on one surface thereof to supply power to the coil portion  140 . The coil portion  140  receives power to generate a driving force via a magnetic field interaction with the magnet  120 . The flexible printed circuit board  150  may be connected to the coil portion  140  to supply power to and control the coil portion  140 . 
     The flexible printed circuit board  150  may receive external power and transmit power to the coil portion  140  through the terminal portion  152  formed on a portion of one surface of the flexible printed circuit board  150 . The coil portion  140  includes an electrode connection portion, extending from two ends of the coil portion  140 , electrically connected to the flexible printed circuit board  150 . In addition, the flexible printed circuit board  150  is coupled to the lateral surface of the housing  130  to expose the terminal portion  152  formed on one surface of the flexible printed circuit board  150  outwardly. As illustrated in  FIG. 1 , the coil portion  140  is disposed on and/or coupled to an external lateral surface of the housing  130 , and the flexible printed circuit board  150  is coupled to the external lateral surface of the housing  130  to cover the coil portion  140  and to face the coil portion  140 . 
     In this case, the flexible printed circuit board  150  is coupled to the housing  130  so that the terminal portion  152  is directed outwardly. The flexible printed circuit board  150  may be a two-sided flexible printed circuit board, the terminal portion  152  may be formed one surface of the flexible printed circuit board  150 , and an electronic device may be mounted on the other surface. The flexible printed circuit board  150  is coupled to the housing  130  so that the other surface on which the electronic device is installed faces the external lateral surface of the housing  130 . 
     As described above, by disposing the terminal portion  152 , formed on the flexible printed circuit board  150 , on an outer surface of the flexible printed circuit board, an external power supply and the terminal portion  152  may be easily coupled. In addition, a flexible printed circuit board is manufactured to be slim, in comparison to a rigid board, to reduce an overall size of an actuator, thereby achieving a more compact structure. 
     The reinforcing portion  160  protrudes from a lower surface of the housing  130  to support a rear surface of the terminal portion  152  to limit deformation of the terminal portion  152 . 
     A region of the flexible printed circuit board  150 , to which the housing  130  contacts and/or is coupled, is supported by the external lateral surface of the housing  130 , however, a portion of the flexible printed circuit board  150 , on which the terminal portion  152  is formed, does not contact the housing  130 , and thus is not supported by the external lateral surface of the housing  130 . Accordingly, the terminal portion  152  of the flexible printed circuit board  150  may be deformed by external force, and when such deformation stress is continuously applied or external force exceeding deformation resistance is applied, a circuit pattern disposed in the flexible printed circuit board  150  may be short-circuited. 
     In particular, when an image sensor to be described later and a printed circuit board  290  on which the image sensor is mounted (refer to  FIG. 5 ) are not integrally assembled and are moved, the terminal portion  152  of the flexible printed circuit board  150  is always exposed, and thus may be easily damaged. Accordingly, the actuator  100  includes the reinforcing portion  160  disposed on the rear surface of the terminal portion  152  to limit deformation of the terminal portion  152 . The reinforcing portion  160  contacts the rear surface of the terminal portion  152  or is spaced apart from the rear surface of the terminal portion  152  at a predetermined interval. 
     When the reinforcing portion  160  is spaced apart from the rear surface of the terminal portion  152 , an interval at which the reinforcing portion  160  is spaced apart from the rear surface of the terminal portion  152  is within a range in which deformation of the terminal portion  152  is allowed. For instance, the flexible printed circuit board  150  allows for some degree of bending, and thus is formed in such a manner that the reinforcing portion  160  is disposed within a range in which such deformation is elastic. 
     The reinforcing portion  160  protrudes from a lower surface of the housing  130  and may be integrally formed with the housing  130 , but the reinforcing portion  160  may alternatively be adhered to a lower surface of the housing  130  after being separately manufactured and formed from the housing  130 . 
     Referring to  FIGS. 2 and 3 , the reinforcing portion  160  further includes lateral protrusion portions  162  that respectively protrude from two ends of the reinforcing portion  160  to cover lateral surfaces of the terminal portion  152  as well as a rear surface of the terminal portion  152 . As such, the reinforcing portion  160  covers the lateral surfaces of the terminal portion  152  to more stably support the terminal portion  152 , and structural strength of each of the terminal portion  152  and the reinforcing portion  160  is further enhanced. 
     As illustrated in  FIGS. 2 and 3 , the terminal portion  152  of the flexible printed circuit board  150  is exposed to supply power to the coil portion. The reinforcing portion  160  may be formed on a rear surface of the terminal portion  152 , thereby reinforcing structural strength of the terminal portion  152  without restriction of power supply of the terminal portion  152 . 
     Referring to  FIG. 3 , the housing  130  may be coupled to the carrier  110  to cover an entire portion of a lower surface of the carrier  110  except for the hollow portion  112  of the carrier  110 , for accommodation of the lens portion, thereby preventing impurities from being introduced to the actuator  100 . 
     Referring back to  FIG. 1 , the housing  130  may include a lateral open portion  134  formed in a lateral surface of the housing  130 , on which the magnet  120  is disposed, in order to expose the magnet  120  to the coil portion  140 . For instance, the lateral open portion  134  corresponding to a shape of the magnet  120  may be formed in a lateral surface of the housing  130  which faces the magnet  120 , among lateral surfaces of the housing  130 . 
     The lateral open portion  134  is formed in one lateral surface of the housing  130  to more effectively generate driving force generated via interaction between the magnetic fields of the magnet  120  and the coil portion  140 . In addition, an accommodation portion  135  is formed at one lateral surface of the housing  130  to stably accommodate and couple the flexible printed circuit board  150  to the housing  130 . 
     In addition, guide balls, or bearings,  125  are disposed between the housing  130  and the carrier  110  to smoothly guide the carrier  110  with respect to the housing  130 . The guide balls  125  are disposed between the housing  130  and the carrier  110 , thereby preventing restriction of movement of the carrier  110  due friction between the housing  130  and the carrier  110 . 
     As illustrated in  FIG. 1 , the actuator  100  further includes a shielding member  190 , a stopper  170 , and a yoke  180 . 
     The shielding member  190  is coupled to the housing  130  to shield external electromagnetic influence and to cover lateral and upper surfaces of the housing  130  and the flexible printed circuit board  150 . The shielding member  190  shields electromagnetic waves. The shielding member  190  may have a shape and size corresponding to the shape and size of the housing  130  and the flexible printed circuit board  150  and may be formed of a material, such as iron, that advantageously shields electromagnetic waves. 
     A coupling portion, or protrusion,  136  protrudes from a lateral portion of the housing  130  and a coupling groove  191  is disposed on the lateral side of the shielding member  190  to couple the shielding member  190  to the housing  130 . The coupling groove  191  corresponds to the coupling portion  136  of the housing  130  so that the coupling portion  136  may be inserted into the coupling groove  191  to fix the shielding member  190  to the housing  130 . 
     The flexible printed circuit board  150  may be coupled to a shielding member by coating an adhesive on one surface of the flexible printed circuit board  150  which faces the shielding member  190 . When the shielding member  190  and the housing  130  are coupled to each other, one surface of the flexible printed circuit board  150 , for instance, the surface on which the terminal portion  152  is formed is disposed to face the shielding member  190 , and the other surface of the flexible printed circuit board  150  may be disposed to face the housing  130 . In this case, the flexible printed circuit board  150  and the shielding member  190  are fixedly coupled to each other by coating an adhesive on one surface of the flexible printed circuit board  150  which faces the shielding member  190 , and the adhesive surface between the flexible printed circuit board  150  and the shielding member  190  may be formed on a region above the terminal portion  152 . 
     The stopper  170  is coupled to an upper surface of the housing  130  to support an upper surface of the carrier  110 . The stopper  170  may be coupled to the housing  130  to prevent the carrier  110  from being separated from the housing  130  and to control movement displacement with which the lens portion moves in a direction along an optical-axis. In order to enhance coupling force between the housing  130  and the stopper  170 , an insertion groove, or hole,  137  and an insertion portion  171  is formed between the housing  130  and the stopper  170 , respectively. For instance, the insertion groove  137  may be recessed in an upper surface of the housing  130 , and the insertion portion  171  may protrude from a lower surface of the stopper  170  at a location corresponding to the insertion groove  137  of the housing  130 . Alternatively, an insertion portion may be formed on the upper surface of the housing  130 , and an insertion groove may be formed in the lower surface of the stopper  170 . 
     In addition, the stopper  170  coupled to the upper surface of the housing  130  may be formed of an elastic, or flexible, material to elastically support the upper surface of the carrier  110 . In addition, the stopper  170  may apply a pressure to the carrier  110  to provide a downward force on the carrier  110 . 
     The yoke  180  is disposed on an external lateral surface of the flexible printed circuit board  150  to control the amplitude and direction of magnetic flux generated by the magnet  120 . The yoke  180  may be formed of a metallic material to enhance intensity of magnetic flux formed by the magnet  120  to effectively generate a driving force for driving the lens portion. 
     As illustrated in  FIG. 1 , the yoke  180  may be coupled to the housing  130 , and, a through hole  181  is formed in the yoke  180  to receive a protrusion portion  138 , formed on a lateral surface of the housing  130 . In this case, a through hole  154  is also formed in the flexible printed circuit board  150  at a location corresponding to the lateral protrusion portion  138 . 
     Referring to  FIG. 4 , the flexible printed circuit board  150  includes a drive integrated circuit (IC)  156  and a multilayer ceramic capacitor (MLCC)  158 . The drive IC  156  is installed on one surface of the flexible printed circuit board  150  to control driving of the lens portion, and the MLCC  158  is installed on one surface of the flexible printed circuit board  150  to control a current applied to the coil portion  140 . The drive IC  156  and the MLCC  158  are installed on a surface of the flexible printed circuit board  150  opposite the surface the terminal portion  152  is disposed on. The terminal portion  152  supplies power to the drive IC  156  and the MLCC  158 . As illustrated in  FIG. 4 , the coil portion  140  is coupled to and disposed on one surface of the flexible printed circuit board  150 , and as described above, the coil portion  140  is configured to electrically connect an electrode connection portion of the coil portion to the flexible printed circuit board  150  in order to receive power through a terminal portion  152  formed on the other surface of the flexible printed circuit board  150 . 
     The drive IC  156  may include a location sensor to detect a location of a magnet, and the location sensor may be a hall sensor. The location sensor detects the location of the magnet, for instance, to determine a displacement of the lens portion in order for the camera module to precisely and rapidly control movement of the lens portion. 
     Referring to  FIG. 5 , the camera module  200  includes a lens portion  210 , a carrier  220 , a magnet  230 , a housing  240 , a coil portion  250 , a flexible printed circuit board  260 , a reinforcing portion  270 , and a shielding member  280 . With reference to  FIGS. 1 through 4 , a description of the aforementioned actuator has been described above. 
     At least one lens and a lens barrel is installed in the lens portion  210  of the camera module  200 . The lens portion  210  includes a focus lens for auto focus and may include a single lens or a plurality of lenses. When the lens portion  210  includes a plurality of lenses, the plurality of lenses may be arranged to be stacked along an optical-axis direction. The lens portion  210  transmits light incident thereon. As illustrated in  FIG. 5 , a lens barrel for covering and accommodating a single lens or a plurality of lenses has a cylindrical shape. 
     As described above, a screw structure may be formed on an outer circumferential surface of the lens portion  210 , and a screw structure may be formed on an inner circumferential surface of the carrier  220  to correspond to the screw structure formed on the outer circumferential surface of the lens portion  210 , and thus the lens portion  210  may be screwed to the carrier  220 . 
     The camera module  200  includes the housing  240 . The housing  240  includes open portions  241  and  242  that expose upper and lower surfaces of the lens portion  210 , respectively, allowing light to pass and to reach the lens portion  210 . For instance, the open portion  242  may be formed in the upper surface of the housing  240  as well as the lower surface. 
     As illustrated in  FIG. 5 , the camera module  200  further includes the image sensor  291  and the printed circuit board  290 . The image sensor  291  collects light transmitted through the lens portion  210  and convert the light into an electrical signal. The image sensor  291  is disposed below the housing  240  so that light transmitted through the lens portion  210  reaches the image sensor  291 . 
     The printed circuit board  290  is coupled to the lower surface of the image sensor  291  through a terminal portion  262  of the flexible printed circuit board  260  to supply a required power or current to the image sensor  291 . The terminal portion may output an electrical signal from the image sensor  291 . 
     The image sensor  291  is mounted on the printed circuit board  290 , the printed circuit board  290  is coupled to a lower surface of the housing  240  or the shielding member  280 , and in this case, the printed circuit board  290  is configured not to interfere with the reinforcing portion  270  formed on the lower surface of the housing  240 . The camera module  200  further includes an infrared filter disposed on an upper surface of the image sensor  291 . 
     The camera module  200  further includes a stopper  281  that is coupled to an upper surface of the housing  240  to support the upper surface of the carrier  220 , and a yoke  282  that is disposed on an external lateral surface of the flexible printed circuit board  260  to control the size and direction of magnetic flux formed by the magnet  230 . 
     As set forth above, an actuator includes a flexible printed circuit board to supply power to a coil portion as one component of a driver for generating driving force required to drive the lens portion, separate from a printed circuit board on which an image sensor is mounted. A reinforcing portion is formed on a lower surface of a housing to protect a terminal portion formed on the flexible printed circuit board, thereby preventing internal short circuits of the flexible printed circuit board. As a result, driving reliability of the actuator may be ensured, and structural strength may be enhanced. 
     The camera module includes a flexible printed circuit board including a terminal portion and a reinforcing portion for protecting the terminal portion of the flexible printed circuit board, thereby easily coupling the terminal portion of the flexible printed circuit board and a printed circuit board on which an image sensor is mounted and stably maintaining the coupling. 
     As set forth above, with a camera module according to exemplary embodiments in the present disclosure, a terminal portion of a flexible PCB may be prevented from being damaged by having a simple structure, without a structural change of the flexible PCB. 
     While this disclosure includes specific examples, it will be apparent to one of ordinary skill in the art 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. 
     As a non-exhaustive example only, a device as described herein may be a mobile device, such as a cellular phone, a smart phone, a wearable smart device (such as a ring, a watch, a pair of glasses, a bracelet, an ankle bracelet, a belt, a necklace, an earring, a headband, a helmet, or a device embedded in clothing), a portable personal computer (PC) (such as a laptop, a notebook, a subnotebook, a netbook, or an ultra-mobile PC (UMPC), a tablet PC (tablet), a phablet, a personal digital assistant (PDA), a digital camera, a portable game console, an MP3 player, a portable/personal multimedia player (PMP), a handheld e-book, a global positioning system (GPS) navigation device, or a sensor, or a stationary device, such as a desktop PC, a high-definition television (HDTV), a DVD player, a Blu-ray player, a set-top box, or a home appliance, or any other mobile or stationary device capable of wireless or network communication. In one example, a wearable device is a device that is designed to be mountable directly on the body of the user, such as a pair of glasses or a bracelet. In another example, a wearable device is any device that is mounted on the body of the user using an attaching device, such as a smart phone or a tablet attached to the arm of a user using an armband, or hung around the neck of the user using a lanyard.