JP2009053331A - Cam structure for camera module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure a stable operation of an end face cam and facilitate initial positioning. <P>SOLUTION: The cam structure is for a camera module which includes: a drive motor; a gear unit which transmits power in linkage with the output shaft of the motor; an end face cam attached to the final gear of the gear unit; a lens frame holding a lens moved in the direction of an optical axis in contact with the end face cam; and a light receiving element which receives light through the lens, wherein the end face cam 5 has a projection part 5c formed so as to project from the periphery and disposed opposite from a cam slope part 5a to a rotation shaft, wherein the gravity center of the end face cam 5 is disposed on the axial center, and wherein an annular groove 5d is formed on the back of the cam 5 and weight reduction is achieved. The position and size of the projection part 5c is set so that the gravity center of the cam 5 is disposed on the axial center. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a camera module mounted on a small portable device such as a mobile phone or a small camera, and more particularly to a cam structure of the camera module.

  In recent years, camera modules are frequently used in small portable devices such as mobile phones. Such a camera module has been developed that is compact, lightweight, and firmly configured while incorporating an autofocus (AF) function and a zoom function (see, for example, Patent Document 1). FIG. 5 is a diagram showing a basic configuration of a conventional camera module. As shown in FIG. 5, the camera module 50 includes a lens frame 52a holding a lens (G1) 51a, a lens frame 52b holding a lens (G2) 51b and a lens (G3) 51c, and lens frames 52a and 52b. A stepping motor 53 that is a driving motor, a gear unit 54 that transmits power in conjunction with the output shaft of the motor 53, an end face cam 55 that is attached to the final stage of the gear unit 54, and a CCD or CMOS type receiver The image element 56 is incorporated in a housing (not shown).

  Cam contact bodies 52c are integrally formed on the lens frames 52a and 52b so as to protrude radially outward from the outer periphery of the lens frame, and the cam contact bodies 52c are cam inclined portions of the end face cam 55 by a tension coil spring 58. Since the end surface cam 55 is rotated by driving the stepping motor 53, the lens frames 52a and 52b guided by the shafts 57a and 57b parallel to the optical axis are moved in the optical axis direction. The focus adjustment function such as auto focus (AF) and zoom is activated.

In order to detect the initial position of the end face cam 55, a reflective tape such as aluminum attached to the end face cam 55 is detected by a sensor such as a photo reflector. Or it was based on the method of detecting by making the protrusion provided extending from the outer periphery of lens frame 52a and 52b pass a photo interrupter.
JP 2005-215539 A

  However, the cam surface 55a is formed on the end face cam 55, but when the cam shape is set to 180 ° or less, the meat for the cam surface 55a is biased to one side with respect to the rotation shaft. As a result, it becomes a single weight state, and the balance of the center of gravity is lost. When the end face cam 55 has a single weight, the moment of inertia increases, and a problem arises that the drive torque must be increased. If there is a single weight, the end face cam 55 is likely to vibrate due to the principle of the vibration motor. In addition, when a sensor is used to detect the initial position of rotation of the end face cam 55, there is a problem that space / cost / man-hour increases, which is disadvantageous.

  An object of the present invention is to solve the above problems and provide a cam structure of a camera module in which an end face cam has a stable cam track and the initial position of the cam can be easily detected.

  The means of the present invention for achieving the above-described object includes a drive motor, a gear unit that transmits power in conjunction with the output shaft of the motor, an end face cam attached to the final stage of the gear unit, In a cam structure of a camera module comprising a lens frame that holds a lens that moves in the optical axis direction in contact with the end face cam, and an image receiving element that receives light through the lens, the end face cam has a cam slope with respect to the rotation axis. A protruding portion is provided on the opposite side of the portion so as to protrude from the outer periphery, and the center of gravity of the end face cam is located at the axial center.

  Further, the projecting portion also serves as a detecting portion for detecting the initial position of the end face cam.

  According to the present invention, in the camera module, a driving motor, a gear unit that transmits power in conjunction with the output shaft of the motor, an end face cam attached to the final stage of the gear unit, and the end face cam are in contact with each other. In the cam structure of the camera module comprising a lens frame that holds a lens that moves in the optical axis direction and an image receiving element that receives light through the lens, the end cam is opposite to the cam inclined surface with respect to the rotation axis. Since the projecting portion is provided so as to protrude from the outer periphery so that the position of the center of gravity of the end face cam is at the axial center, the track of the end face cam can operate stably. Further, since the projection serves also as a detection unit when the initial position of the end face cam is performed, the initial position of the end face cam can be easily detected.

  Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. 1 is a perspective view of an end face cam of a camera module according to an embodiment of the present invention, FIG. 2 is a plan view of the same end face cam, FIG. 3 is a cross-sectional view showing the AA cross section of FIG. It is a bottom view.

  First, since the basic configuration of the camera module 10 according to the embodiment of the present invention is the same as that described in the prior art, the description thereof is omitted. As shown in FIG. 1, the end face cam 5 of the camera module 10 has a cam slope portion 5 a formed in a range of 180 °, and protrudes to the outer periphery opposite to the cam slope portion 5 a with respect to the rotation shaft 9. Thus, the protrusion 5c is integrally formed. A concentric annular groove 5d is formed on the back side. The position and size of the protruding portion 5c are set so that the center of gravity of the end face cam 5 comes to the axial center.

  Next, a method for detecting the initial position of the end face cam 5 of the camera module 10 will be described. During the initial reset operation, the stepping motor 53 is rotated to hit the protrusion 5c against the stopper provided in the housing. The hit position is recognized as the origin, and thereafter, the lens position is grasped by the number of pulses of the stepping motor 53.

  Next, effects of the embodiment of the present invention will be described. The weight is reduced by the concave groove 5d provided on the back surface of the end face cam 5, and a protruding portion 5c protruding from the outer peripheral portion on the opposite side of the cam slope portion 5a is provided so that the center of gravity of the end face cam 5 is centered. As a result, the end cam 5 operates with a stable trajectory even if it turns at a high speed, and the positions of the lenses 51a, 51b and 51c are accurately determined. Further, when the initial position of the end face cam 5 is detected, the origin can be easily recognized by applying the projection 5c to the stopper of the casing outside the end face cam 5, which is advantageous from the viewpoint of space / cost / man-hour. became.

  The camera module of the present invention can be widely applied to mobile phones, small cameras, PDAs and the like.

It is a perspective view of the end face cam which is an embodiment of the present invention. It is a top view of the end face cam which is an embodiment of the present invention. It is sectional drawing which shows the AA cross section of FIG. It is a bottom view of the end face cam which is an embodiment of the present invention. It is explanatory drawing which shows the basic composition of the conventional camera module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 5 End surface cam 5a Cam slope part 5c Projection part 6 Image receiving element 9 Rotating shaft 10 Camera module 51a, 51b, 51c Lens 52a, 52b Lens frame 53 Stepping motor 54 Gear unit

Claims (2)

  A drive motor, a gear unit that transmits power in conjunction with the output shaft of the motor, an end face cam attached to the final stage of the gear unit, and a lens that moves in the optical axis direction in contact with the end face cam are held. In the cam structure of a camera module comprising a lens frame and an image receiving element that receives light through the lens, the end face cam is provided with a protrusion so as to protrude from the outer periphery on the opposite side of the cam inclined surface with respect to the rotation shaft. A cam structure for a camera module, characterized in that the center of gravity of the end face cam is located at the axial center.   2. The cam structure of a camera module according to claim 1, wherein the protrusion serves also as a detection unit for detecting an initial position of the end face cam.

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