Patent Publication Number: US-2016223777-A1

Title: Actuator and camera module

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit under 35 USC 119(a) of Korean Patent Application No. 10-2015-0016223 filed on Feb. 2, 2015, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference for all purposes. 
     BACKGROUND 
     1. Field 
     The following description relates to an actuator and a camera module. 
     2. Description of Related Art 
     In general, a digital camera captures images using an image sensor such as a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS) instead of a film. A camera module for capturing images has been used in various devices such as in mobile devices having a camera function, tablet personal computers (PC), and monitors or surveillance cameras installed in vehicles, due to having a relatively small volume and excellent performance. In particular, camera modules used in mobile devices have been gradually multifunctionalized, miniaturized, and lightened, in accordance with current trends. 
     Camera modules recently used in mobile devices commonly have an auto focusing function and an optical image stabilization (OIS) function, and devices included in a camera module also need to meet miniaturization requirements by virtue of the miniaturization of lenses and increases in levels of optical performance. Various types of actuator are commonly used to drive camera modules, such as voice coil motors (VCM), step motors, piezoelectric actuators, micro electro mechanical systems (MEMS), and so on. A voice coil motor (VCM)-type actuator, commonly used as an actuator in a camera module, uses Lorentz force, that is, electromagnetic force generated between an electrical 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 aspect, an actuator and a camera module is provided in which a terminal portion or a driver integrated circuit mounted on a printed circuit board prevents damage to the printed circuit board while having a simplified structure. The structure of the printed circuit board is simplified through various connection pads, a coil portion, and a driver IC being disposed on one surface of the printed circuit board. In addition, a single sided printed circuit board may be used so as to reduce manufacturing costs. 
     In another general aspect, an actuator and a camera module prevents damage to a coil portion or a driver IC, which may occur as a lens barrel disposed to face the other surface of the printed circuit board is driven, by disposing various connection pads, a coil portion, and a driver IC on one surface of the printed circuit board. 
     In another general aspect, an actuator includes a printed circuit board having an external connection pad formed on one surface of the printed circuit board; a magnet disposed to face another surface of the printed circuit board; a coil portion disposed on the one surface of the printed circuit board; and a driver integrated circuit (IC), installed on the one surface of the printed circuit board, configured to control a current applied to the coil portion. 
     In another general aspect, a camera module includes a lens barrel; a lens disposed in the lens barrel; a housing, wherein the lens barrel is disposed in the housing; and an actuator configured to move the lens barrel along an optical axis of the lens. The actuator includes a printed circuit board, coupled to the housing, having an external connection pad formed on one surface of the printed circuit board, a magnet coupled to an outer circumferential surface of the lens barrel to face another surface of the printed circuit board, a coil portion installed on the one surface of the printed circuit board, and a driver integrated circuit (IC), disposed on the one surface of the printed circuit board, configured to control a current applied to the coil portion. 
     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 schematic diagram illustrating an actuator; 
         FIG. 2  is a plan view illustrating a printed circuit board used in an actuator; 
         FIG. 3  is a perspective view of a camera module; and 
         FIG. 4  is an exploded perspective view 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. 
     Referring to  FIGS. 1 and 2 , an actuator  100  includes a printed circuit board  110 , a magnet  120 , a coil portion  130 , and a driver integrated circuit (IC)  140 . The printed circuit board  110  includes an external connection pad  111  formed on one surface thereof. The external connection pad  111  is formed on one surface of the printed circuit board  110  and connects the printed circuit board  110  to an external power source, an image sensor, or other external component. 
     The external connection pad  111  may be formed via various methods of coating, plating, or deposition a conductive material. The external connection pad  111  protrudes from one surface of the printed circuit board  110  or may be formed in such manner that one surface of the external connection pad  111  is concave from one surface of the printed circuit board  110 . 
     Although  FIG. 2  shows six external connection pads  111 , the number of external connection pads may vary according to design or process requirements. Similarly, a location of one surface of the printed circuit board  110 , on which the external connection pad  111  is formed, is not limited to a lower end of the printed circuit board  110  shown in  FIG. 2 . The external connection pad  111  connects the printed circuit board  110  to an external power source and other external components. 
     The printed circuit board  110  may be a flexible printed circuit board or a rigid printed circuit board. In the case of the flexible printed circuit board, the actuator  100  is slim, while a rigid printed circuit board provides rigidity to support the coil portion  130  and the driver IC  140 , and will be described later. 
     Formed on the surface of the printed circuit board  110  is a coil connection pad  113  electrically connected to the coil portion  130 . The coil connection pad  113  may be formed via various methods of coating conductive paste, plating, or deposition. The coil connection pad  113  protrudes from one surface of the printed circuit board  110  or may be formed in such way that a portion of the coil connection pad  113  is concave, or formed as a groove in one surface of the printed circuit board  110 . The position of the coil connection pad  113  may be changed in various manners, according to design or process requirements, as long as the coil connection pad  113  is electrically connected to the coil portion  130 . The connection between the coil connection pad  113  and the coil portion  130  will be described later. 
     The magnet  120  is disposed to face the other surface of the printed circuit board  110 . That is, the magnet  120  may face the coil portion  130  and the driver IC  140 , to be described later, with the printed circuit board  110  disposed therebetween. 
     The magnet  120  generates a magnetic field to interact with the coil portion  130  to generate a Lorenz force, described below. Accordingly, in a situation in which the coil portion  130  is fixed, the magnet  120  may be displaced through the Lorenz force. Similarly, in a situation in which the magnet  120  is fixed, the coil portion  130  may be displaced through the Lorenz force. 
     The coil portion  130  is installed on one surface of the printed circuit board  110 . The coil portion  130  may be formed by winding consecutive unit coils several times or may be formed by connecting a plurality of discontinuous unit coils to each other. When current is applied to the coil portion  130 , an electrical field is generated and thus may generate a Lorentz force together with the magnet  120 . A unit coil includes a conductive material. In addition, the unit coil includes a material with ductility so the shape of the coil portion  130  may be easily formed. Since the coil portion  130  is installed on one surface of the printed circuit board  110 , and the magnet is disposed to face an opposite surface of the printed circuit board  110 , the coil portion  130  does not directly face the magnet  120 , thereby preventing problems such as damage due to contact between the coil portion  130  and the magnet  120 . 
     The driver IC  140  is installed on one surface of the printed circuit board  110  so as to control current applied to the coil portion  130 . That is, the driver IC  140  controls a current applied to the coil portion  130  so as to control the amplitude and direction of Lorentz force generated between the coil portion  130  and the magnet  120 . 
     An opening  131  in the coil portion  130  is formed to include a gap between the coil portion  130  and the driver IC  140  in order to control a current applied to the coil portion  130 . Since the driver IC  140  is installed on one surface of the printed circuit board  110 , the driver IC  140  does not directly face the magnet  120 , thereby preventing problems such as damage due to contact between the driver IC  140  and the magnet  120 . Accordingly, in the actuator  100 , the magnet  120  faces the coil portion  130  and the driver IC  140  across the printed circuit board  110 , thereby preventing damage to the magnet  120 , the coil portion  130 , or the driver IC  140 , which may occur as the magnet  120  or the printed circuit board  110  moves. Additionally, disposing the coil portion  130 , the driver IC  140 , and the external connection pad  111  and coil connection pad  113  on one surface of the printed circuit board  110 , reduces manufacturing costs. 
     The driver IC  140  includes a location sensor to detect a location of the magnet  120 . That is, the location sensor detects a location of the magnet  120 , and the driver IC  140  uses the detected location of the magnet  120  to control a current applied to the coil portion  130 . Here, the location sensor may be a hall sensor. The hall sensor may detect changes in magnetic force. Accordingly, the location of the magnet  120  may be more precisely detected. As such, the actuator  100  detects a location of the magnet  120  so as to precisely control displacement of the magnet  120  or the printed circuit board  110 . 
     As illustrated in  FIGS. 3 and 4 , the camera module  1000  includes a lens barrel  200 , a housing  300 , and the actuator  100 , and further includes a shield can  400 . The lens barrel  200  accommodates a lens. That is, the lens barrel  200  includes a cylindrical accommodation hole  210  accommodating a lens disposed along an optical-axis direction. The lens barrel  200  may accommodate a plurality of lenses in the accommodation hole  210  so as to focus an object image on an image sensor (not shown). The lens barrel  200  may include a spacer (not shown) so as to maintain a predetermined interval between a plurality of lenses disposed in the lens barrel  200 . 
     The housing  300  accommodates the lens barrel  200  therein. That is, the housing  300  covers an outer circumferential surface of the lens barrel  200  in order to protect the lens barrel  200  from external impacts. The housing  300  accommodates the lens barrel  200  so as to allow the lens barrel  200  to be movable along an optical axis by the actuator  100 . The housing  300  further includes a guide ball, or ball bearing, guiding movement of the lens barrel  200  along an optical-axis direction. 
     Here, the printed circuit board  110  is coupled to the housing  300 , and the magnet  120  is coupled to an outer circumferential surface of the lens barrel  200  so as to face the other surface of the printed circuit board  110 . Since the printed circuit board  110  is fixed to the housing  300 , restricting displacement of the coil portion  130 , and the magnet  120  is movable with the lens barrel  200  within the housing  300  along the optical axis, the lens barrel  200  is movable along an optical axis according to a Lorentz force generated between the coil portion  130  and the magnet  120 . 
     As illustrated in  FIG. 3 , the external connection pad  111  is exposed externally from the shield can  400  when the shield can  400  is coupled to the housing  300 . In this case, the external connection pad  111  may be easily coupled to an external power source and other external components. The shield can  400  covers the housing  300  to shield electromagnetic waves radiated from the actuator  1000 . That is, the shield can  400  is coupled to and surrounds an external portion of the housing  300  in which the lens barrel  200  and the actuator  100  are disposed. In addition, the shield can  400  protects the camera module  1000  from external impacts. 
     The shield can  400  may be formed of a dielectric material so as to shield electromagnetic waves. In addition, an opening  410  exposing the lens barrel  200  outward is formed in an upper surface of the shield can  400 . 
     As such, in the camera module  1000  the coil portion  130 , the driver IC  140 , and the external connection pad  111  and the coil connection pad  113  are installed on one surface of the printed circuit board  110  instead of the other surface facing the lens barrel  200 , thereby preventing damage to the coil portion  130  or the driver IC  140 , which may occur as the lens barrel  200  moves on an optical axis. In addition, since the coil portion  130  and the driver IC  140  may be exposed externally from the housing  300 , when the coil portion  130  or the driver IC  140  is damaged, the coil portion  130  or the driver IC  140  may be easily repaired. 
     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. 
     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.