JP2009186650A - Camera module and mobile terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camera module capable of shortening a time required in a period until a mirror frame is stabilized in a prescribed position after electrifying a coil, and thereby capable of preventing a shooting chance from being missed, and to provide a mobile terminal of excellent use feeling. <P>SOLUTION: The camera module has the mirror frame for holding an imaging optical system for guiding a subject light, a lens driving part having the coil and a magnet, and for moving the mirror frame along an optical axis direction of the imaging optical system, with an electromagnetic force generated by electrifying the coil, and plate-like spring members attached in two portions of optical-axis-directional front and rear sides of the imaging optical system in the mirror frame, wherein at least one of the spring members attached to the two portions in the mirror frame is constituted of a plurality of spring members. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a small camera module suitable for being incorporated in a portable terminal.

  Conventionally, a small and thin camera module is mounted on a portable terminal such as a cellular phone, and it is possible to transmit not only shooting but also audio information as well as image information to a remote place. . Some of these camera modules include a lens driving unit for moving the photographing lens group along the optical axis so as to enable autofocus photographing.

As such a lens driving device for a camera module, a device in which plate-like spring members are attached at two locations on the front and rear of a lens frame is known (for example, see Patent Document 1).
JP 2006-201525 A

  As a lens driving unit of a camera module built in a cellular phone or the like, a so-called voice coil motor having a coil and a magnet and moving a lens frame using electromagnetic force generated by energizing the coil is used. In many cases, it is held and urged by leaf springs arranged before and after the lens frame.

  FIG. 8 is a cross-sectional view showing a configuration of a conventional camera module.

  As shown in the drawing, a coil 33 is wound around a lens frame 22 that holds the imaging optical system 10, and a magnet 32 is disposed opposite to the coil 33. The magnet 32 is held by a U-shaped yoke 31.

  The lens frame 22 is movable in the direction of the optical axis O, and a plate spring 23 is disposed on the subject side of the lens frame 22 and a plate spring 24 is disposed on the image pickup device side. 22 is urged toward the image sensor side. The inner part of the leaf spring 23 is fixed to the end of the lens frame 22 on the subject side, and the outer part is fixed to the upper housing 11. The inner side of the leaf spring 24 is fixed to the end of the lens frame 22 on the image sensor side, and the outer side is fixed to the lower housing 12.

  When the coil 33 is not energized, the lens frame 22 is brought into contact with the lower housing 12 by this urging force and stopped. When the coil 33 is energized, the lens frame 22 moves to the subject side in the optical axis direction by electromagnetic force.

  FIG. 9 is a diagram showing the behavior of the lens frame when the lens of the conventional camera module shown in FIG. 8 is driven. The figure (a) is a figure which shows the state of electricity supply to a coil, and the figure (b) is a schematic diagram which shows the behavior of the lens frame at the time of supplying electricity to a coil.

  As shown in FIG. 6A, when a predetermined amount of current is applied to the coil, the lens frame starts moving in the optical axis direction, but is shown in FIG. It takes a lot of time to vibrate and stop at the target position. Shooting must be performed in a stable state so that the lens frame, that is, the imaging optical system is within a predetermined range of the target position. After the photographer operates the button corresponding to the release button, exposure is actually performed. It will cause a big time lag before it is released. For this reason, when shooting a moving object or the like, a shooting opportunity is missed, and a desired image cannot be obtained.

  In view of the above problems, the present invention can shorten the time from when the coil is energized until the lens frame stabilizes at a predetermined position, thereby obtaining a camera module that does not miss a shooting opportunity, The object is to obtain an excellent portable terminal.

  The above object is achieved by the invention described below.

  1) A lens frame that holds an imaging optical system that guides subject light, and a lens driving unit that has a coil and a magnet and moves the lens frame in the optical axis direction of the imaging optical system by electromagnetic force generated by energizing the coil. A camera module having plate-like spring members attached at two positions in the optical axis direction of the imaging optical system of the lens frame, and at least one of the spring members attached at two positions of the lens frame. Is a camera module comprising a plurality of spring members.

  2) The camera module according to 1), wherein the plurality of spring members are formed of the same material.

  3) The camera module according to 1), wherein the plurality of spring members are formed of different materials.

  4) A mobile terminal comprising the camera module according to any one of 1) to 3).

  That is, the invention of the present application has been made based on the finding that the transitional vibration during the movement of the lens frame has a damping effect when at least one of the springs attached to the front and rear of the lens frame is composed of a plurality of spring members. . When the leaf springs are stacked and assembled, the springs rub against each other when the lens frame moves, and it is assumed that the frictional force at the time of rubbing acts as a damper.

  According to the present invention, it is possible to shorten the time from when the coil is energized to when the lens frame is stabilized at a predetermined position, thereby obtaining a camera module that does not miss a shooting opportunity, and excellent in usability. A portable terminal can be obtained.

  Hereinafter, the present invention will be described in detail by embodiments, but the present invention is not limited thereto.

  FIG. 1 is a cross-sectional view showing an example of a camera module 50 according to the present embodiment. FIG. 2 is an exploded perspective view of the camera module 50 shown in FIG.

  As shown in FIGS. 1 and 2, a coil 33 is wound in an annular shape outside the lens frame 22 that holds the imaging optical system 10, and a magnet 32 is disposed facing the coil 33. Yes. The magnet 32 is held by a yoke 31 having a U-shaped cross section.

  The lens frame 22 is movable in the direction of the optical axis O. Two leaf springs 23A and 23B are arranged on the subject side of the lens frame 22 so as to overlap each other, and one leaf spring 24 is arranged on the image sensor side. The lens frame 22 is disposed and holds the lens frame 22 and urges the lens frame 22 toward the image sensor.

  The inner portion 23Au of the leaf spring 23A is fixed to the end of the lens frame 22 on the subject side. Further, the outer portions 23As and 23Bs of the leaf springs 23A and 23B are fixed to the upper housing 11. The inner part 24u of the leaf spring 24 is fixed to the end of the lens frame 22 on the image sensor side, and the outer part 24s is fixed to the lower housing 12. Although not shown, the lower housing 12 is assembled with a substrate on which an image sensor is mounted.

  When the coil 33 is not energized, the lens frame 22 comes into contact with the lower housing 12 by the urging force of the leaf spring and stops. When the coil 33 is energized, the lens frame 22 is movable to the subject side in the optical axis direction by electromagnetic force.

  FIG. 3 is a cross-sectional view showing another example of the camera module 50 according to the present embodiment. Regarding the camera module shown in the figure, only the parts different from those shown in FIG. 1 will be described.

  The lens frame 22 of the camera module 50 shown in FIG. 1 has two leaf springs 24A and 24B overlapped on the image sensor side of the lens frame 22, and one leaf spring 23 is disposed on the subject side. While holding the frame 22, the lens frame 22 is urged toward the image sensor. The inner portions of the leaf springs 24A and 24B are fixed to the end of the lens frame 22 on the image sensor side, and the outer portions are fixed to the lower housing 12. The inner part of the leaf spring 23 is fixed to the end of the lens frame 22 on the subject side, and the outer part is fixed to the upper housing 11. Although not shown, the lower housing 12 is assembled with a substrate on which an image sensor is mounted.

  The camera module shown in FIG. 1 has a plurality of leaf springs attached to the subject side of the lens frame 22, and the camera module shown in FIG. 3 has a plurality of leaf springs attached to the imaging element side of the lens frame 22. It is. However, the present invention is not limited thereto, and a plurality of leaf springs may be attached to both the subject side and the image sensor side of the lens frame 22.

  As described above, at least one of the spring members attached to the front and rear in the optical axis direction of the imaging optical system of the lens frame is constituted by a plurality of spring members, so that a predetermined movement is performed after the coil is energized. The time until the lens frame is stabilized at a later position can be significantly reduced as compared with the conventional camera module.

  This is presumed that the leaf springs rub against each other when the lens frame is moved by overlapping the leaf springs, and the frictional force at the time of rubbing acts as a damper.

  FIG. 4 is an external view of a mobile phone 100 that is an example of a mobile terminal including the camera module 50 according to the present embodiment.

  In the mobile phone 100 shown in the figure, an upper casing 71 as a case having display screens D1 and D2 and a lower casing 72 having an operation button 60 as an input unit are connected via a hinge 73. Yes. The camera module 50 is built below the display screen D <b> 2 in the upper casing 71, and is arranged so that the camera module 50 can capture light from the outer surface side of the upper casing 71.

  Note that the position of the camera module may be disposed above or on the side of the display screen D2 in the upper casing 71. Of course, the mobile phone is not limited to a folding type.

  FIG. 5 is a control block diagram of the mobile phone 100.

  As shown in the figure, the camera module 50 is connected to the control unit 101 of the mobile phone 100 and outputs image signals such as luminance signals and color difference signals to the control unit 101.

  On the other hand, the mobile phone 100 controls each part in an integrated manner, and also executes a control part (CPU) 101 that executes a program corresponding to each process, an operation button 60 that is an input part for inputting a number and the like, Display screens D1 and D2 for displaying predetermined data and captured images, a wireless communication unit 80 for realizing various information communications with an external server, a system program for mobile phone 100, various processing programs, and a terminal A storage unit (ROM) 91 that stores necessary data such as an ID, and various processing programs and data executed by the control unit 101 or processing data, image data from the camera module 50, and the like are temporarily stored. Or a temporary storage unit (RAM) 92 used as a work area.

  Further, the image signal input from the camera module 50 is stored in the nonvolatile storage unit (flash memory) 93 by the control unit 101 of the mobile phone 100, or displayed on the display screens D1 and D2. The image information is transmitted to the outside via the wireless communication unit 80.

  For the camera module according to the present embodiment and the conventional camera module, the time from when the coil was energized until the lens frame was stabilized at the position after movement (predetermined target position) was measured.

  The experiment was conducted on a total of seven types, one type of conventional camera module and six types of examples according to the present invention as comparative examples.

  Hereinafter, experimental conditions will be described.

(Number of springs and materials)
The number of springs and materials used in the comparative examples and Examples 1 to 6 are combinations shown in the following (Table 1).

  In Table 1, beryllium copper was C1720, phosphor bronze was C5210, stainless steel was SUS304, and resin sheets were polyester films.

  FIG. 6 is a plan view showing the spring shape used. FIG. 4A shows the shape of a metal leaf spring arranged on the subject side of the lens frame, and FIG. 4B shows the shape of a metal leaf spring arranged on the image sensor side of the lens frame. Yes, FIG. 3C shows the shape of the resin sheet.

  The mass of the movable part, that is, the mass of the lens frame and the imaging optical system was 0.23 g.

(Measurement condition)
The time from when the coil is energized until the lens frame moves and stabilizes is the time until the vibration amplitude becomes ± 20% or less (± 0.016 mm) of the movement stroke with respect to the movement stroke (0.08 mm). It was.

  FIG. 7 is a diagram showing the measurement conditions for the time until the above stabilization. As shown in the figure, when the movement stroke to the target position is L, the time until the amplitude becomes ± 0.2 L or less was measured as the time until stabilization.

  (Table 2) shows the measured values of the time from when the coil is energized until it becomes stable in each of the comparative example and Examples 1 to 6.

  As shown in Table 2, Examples 1, 2, 3, 5 in which either one of the front and rear is constituted by two spring members as compared with the comparative example in which one leaf spring is arranged before and after the lens frame. , 6 and Example 4 constituted by two spring members on both sides, it can be seen that the time until stabilization is significantly shortened compared to the comparative example.

  That is, by configuring at least one of the spring members attached to the two positions of the lens frame with a plurality of spring members, it is possible to suppress transient vibration during the movement of the lens frame and until it is stable at a predetermined position. It becomes possible to shorten the time.

It is sectional drawing which shows an example of the camera module which concerns on this Embodiment. It is a disassembled perspective view of the camera module shown in FIG. It is sectional drawing which shows the other example of the camera module which concerns on this Embodiment. It is an external view of a mobile phone which is an example of a mobile terminal provided with the camera module according to the present embodiment. It is a control block diagram of a mobile phone. It is a top view which shows the used spring shape. It is a figure which shows the measurement conditions of the time until it stabilizes. It is sectional drawing which shows the structure of the conventional camera module. It is a figure which shows the behavior of the lens frame at the time of the lens drive of the conventional camera module shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Imaging optical system 11 Upper housing | casing 12 Lower housing | casing 22 Mirror frame 23, 23A, 23B, 24, 24A, 24B Leaf spring 31 Yoke 32 Magnet 33 Coil 50 Camera module 100 Mobile phone O Optical axis

Claims (4)

A lens frame that holds an imaging optical system that guides subject light; a lens driving unit that has a coil and a magnet and moves the lens frame in the optical axis direction of the imaging optical system by electromagnetic force generated by energizing the coil; In a camera module having plate-like spring members attached at two locations on the front and back in the optical axis direction of the imaging optical system of the lens frame,
At least one of the spring members attached to two positions of the lens frame is composed of a plurality of spring members. The camera module according to claim 1, wherein the plurality of spring members are formed of the same material. The camera module according to claim 1, wherein the plurality of spring members are formed of different materials. A portable terminal comprising the camera module according to claim 1.

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