JP5574292B2 - Lens drive device, autofocus camera and mobile terminal with camera - Google Patents

Description

  The present invention relates to a lens driving device that moves a lens support by energizing a coil, an autofocus camera equipped with the lens driving device, and a camera-equipped mobile terminal.

In Patent Document 1, a coil body is provided on the outer periphery of the lens support, a magnet disposed on the outer periphery of the lens support is provided opposite the coil body, the lens support is elastically supported by a spring, and the coil body is energized. It is disclosed that the lens support is moved to a predetermined position by balancing the electromagnetic force generated with respect to the magnetic field of the magnet and the elastic force of the spring.
In Patent Document 2, a coil body is provided on the outer periphery of the lens support, a magnet disposed on the outer periphery of the lens support is provided opposite the coil body, and the lens support is braked by frictional engagement with the lens support. And guiding the movement of the lens support.

JP 2009-271204 A JP-A-2005-352102

However, in the technique of Patent Document 1, as shown in FIG. 6, due to the bias of the elastic force of the spring and the bias of the magnetic field strength of the magnet acting on the coil body during and after the movement of the lens support. The body 101 may be tilted (tilt) θ. In FIG. 6, reference numeral 103 is a coil body, and 105 is a magnet.
When the lens support is tilted in this way, there is a disadvantage that a clear image cannot be obtained. Particularly, in recent years, there is a high demand for accuracy with respect to the tilt of the lens support.

  Further, the technique of Patent Document 2 can prevent the lens support from being tilted by the guide shaft, but there is a problem that it is difficult to hold the position of the lens support after the movement because no spring is provided.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a lens driving device, an autofocus camera, and a camera-equipped mobile terminal that can maintain the position of the lens support after movement and prevent the lens support from tilting.

The invention according to claim 1 is a lens support for supporting the lens, a coil body fixed to the outer periphery of the lens support, a spring for movably supporting the lens support, and an outer peripheral side of the lens support The magnet is disposed opposite to the coil body and the guide shaft is provided in the optical axis direction of the lens, and the balance between the electromagnetic force generated against the magnetic field of the magnet and the elastic force of the spring when the coil body is energized. The lens driving device moves the lens support to a predetermined position by the lens support, and the lens support has an engaging portion that engages with the guide shaft on the outer peripheral side, and the engaging portion has an inner peripheral side of the lens support. Yes and recessed dents formed lens characterized by recessed engagement portion of the lens support is engaged from an inner circumferential side of the lens support the guide shaft in the movement and stop position of the lens support Is a driving device

  According to a second aspect of the present invention, in the first aspect of the invention, an annular yoke having a lens support disposed on the inner periphery thereof is provided, and the spring is disposed at least one of the front and rear in the optical axis direction of the yoke. The yoke has a polygonal shape in plan view when viewed from the optical axis direction, the magnet is disposed at each corner of the yoke, and the guide shaft is disposed between the corners of the yoke. And

  The invention according to claim 3 is the invention according to claim 2, wherein the yoke has an outer peripheral wall and an inner extending portion extending from one end of the outer peripheral wall in the optical axis direction to the inner peripheral side, One end is held in the fitting hole of the inner extending portion.

  A fourth aspect of the invention includes the lens driving device according to any one of the first to third aspects, an image sensor provided on the image forming side of the lens of the lens support, and a control unit. The autofocus camera is characterized in that a current is passed so as to move the lens support 7 to the in-focus position with the highest contrast while comparing the peaks of the high-frequency component of the contrast of the image sensor.

  The invention described in claim 5 is a mobile terminal device with a camera, in which the autofocus camera according to claim 4 is mounted.

According to the first aspect of the present invention, when a current is passed through the coil body, the lens support moves in the optical axis direction of the lens due to the electromagnetic force generated with respect to the magnetic field of the magnet, and the electromagnetic force acting on the coil body. And stops at a position where the elastic force of the spring balances.
Since the engaging portion provided on the lens support is engaged with the guide shaft even when the lens support is moved and stopped, the posture of the lens support is maintained during the movement and after stop. It is possible to prevent the tilt from occurring.

  According to the second aspect of the present invention, the same effect as the first aspect of the invention can be obtained, the magnet is disposed at the corner of the yoke, and the guide shaft is disposed between the corners of the yoke. Therefore, when the guide shaft is provided, the magnet can be disposed without obstructing the guide shaft, and the guide shaft can be provided without increasing the outer shape of the yoke in plan view.

  According to the invention of the third aspect, the same effect as that of the invention of the second aspect is obtained, and the guide shaft is easily fixed and assembled by fitting the guide shaft into the fitting hole of the yoke. it can.

  According to the invention described in claim 4, it is possible to provide an autofocus camera having the same effects as the invention described in any one of claims 1 to 3.

  According to the invention described in claim 5, it is possible to provide a camera-equipped mobile terminal device having the same operational effects as the invention described in claim 4.

It is a cross-sectional view of the lens driving device according to the first embodiment. It is a disassembled perspective view of the lens drive device concerning a 1st embodiment. It is sectional drawing which cut | disconnects and shows the lens drive device which concerns on 1st Embodiment in the AA position shown in FIG. It is a perspective view which shows the external appearance of the lens drive device which concerns on 1st Embodiment. It is a figure explaining the effect | action by the lens drive device which concerns on 1st Embodiment, and is a schematic block diagram of a lens drive device. It is a figure explaining the effect | action of the conventional lens drive device, and is a schematic block diagram of the conventional lens drive device.

  Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS. The lens driving device 1 according to the first embodiment is a lens driving device for an autofocus camera incorporated in a mobile phone.

  As shown in FIG. 2, the lens driving device 1 includes an annular yoke 3, a lens support 7, a frame 8 and a front spring 9 disposed on the front side of the yoke 3 in the optical axis direction, and a rear side of the yoke 3. A base 5 and a rear spring 11 are provided, and a spacer (insulating material) 17 is disposed between the rear spring 11 and the yoke 3. A guide shaft 41 is provided on the yoke 3.

The yoke 3 has a quadrilateral outer periphery when viewed from the front side and a circular inner surface when viewed from the front, and extends from the front end of the outer peripheral wall 3a, the inner peripheral wall 3b, and the outer peripheral wall 3a to the inner peripheral side. The inner extending wall 3c connects the inner peripheral wall 3b and the outer peripheral wall 3a. The outer peripheral wall 3a, the inner peripheral wall 3b, and the inner extending wall 3c have a substantially U-shaped cross section.
The inner peripheral wall 3b of the yoke 3 is provided at a position corresponding to the four corners 14, and a space 12 is formed between the adjacent inner peripheral walls 3b and 3b.

Moreover, as shown in FIG. 1, the magnet 13 is provided in the four corner | angular parts 14 of the yoke 3 on the inner peripheral side surface of the outer peripheral wall 3a.
A fitting hole 42 for the guide shaft 41 is formed between the corner portions 14 and 14 in the inner extending wall 3 c of the yoke 3. Two fitting holes 42 are provided at positions facing each other.

  Each of the magnets 13 has a substantially quadrangular shape when viewed from the front side, and an inner peripheral side of the magnet 13 has an arc shape along the outer periphery of the lens support 7. The magnetic poles are different between the inner peripheral side and the outer peripheral side. For example, the inner peripheral surface is an N pole and the outer peripheral surface is an S pole.

The lens support 7 has a substantially cylindrical shape, and is provided so as to be movable in the optical axis direction (front-rear direction) X of the lens on the inner peripheral side of the yoke 3 as shown in FIG. An annular coil body 15 is fixed to the outer periphery of the lens support 7.
As shown in FIGS. 1 and 2, the lens support 7 has an engaging portion 43 that protrudes on the outer peripheral side and engages with the guide shaft 41 at two positions with an interval of 180 degrees in the circumferential direction. They are provided parallel to each other.

The guide shaft 41 is a cylinder, and the two guide shafts 41 are provided at positions corresponding to the engaging portions 43. Each engaging portion 43 is formed with a substantially semicircular recess 45, and the edge of the recess 45 abuts against the side surface of the guide shaft 41.
As shown in FIG. 3, the guide shaft 41 has a front end fitted in a fitting hole 42 formed in the yoke 3, and a rear end abutted on the base and fixedly bonded.

  As shown in FIG. 2, the front spring 9 has a flat plate shape in a natural state before assembly, and is arranged on the outer peripheral side portion 9b having a rectangular shape in plan view and the circular shape in plan view arranged on the inner periphery of the outer peripheral side portion 9b. The inner peripheral side portion 9a and the four arm portions 9c connecting the outer peripheral side portion 9b and the inner peripheral side portion 9a.

The rear spring 11 has a flat plate-like natural state before assembly, and is arranged on the outer periphery side portion 11b having a rectangular shape in plan view, and on the inner periphery of the outer periphery side portion 11b, and has a circular shape in plan view. And the four arm portions 11c that connect the outer peripheral side portion 11b and the inner peripheral side portion 11a, but unlike the front spring 9, the outer peripheral side portion 11b and the inner peripheral side portion 11a are on one side portion. 30 and the other side 32 are separated into two parts.
An insertion portion 46 for the vibration shaft 41 is formed in the rear spring 11.

  The outer peripheral side portion 9 b of the front spring 9 is sandwiched between the frame 8 and the yoke 3, and the inner peripheral side portion 9 a is fixed to the front end of the lens support 7. The outer peripheral side portion 11 b of the rear spring 11 is sandwiched between the base 5 and the rear spacer 17, and the inner peripheral side portion 11 a is fixed to the rear end of the lens support 7. Thus, the lens support 7 is supported by the front spring 9 and the rear spring 11 so as to be movable in the front-rear direction.

  When the lens support body 7 moves forward, the lens support body 7 has a resultant force of elastic forces in the front-rear direction of the front spring 9 and the rear spring 11 and an electromagnetic force generated between the coil body 15 and the magnet 13. Stops at the position where they hang.

  As shown in FIG. 3, the lens driving device 1 is attached to a substrate 21 on which an image sensor 19 is mounted. The image sensor 19 is, for example, a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor).

Next, assembly, operation, and effects of the lens driving device 1 according to the embodiment of the present invention will be described.
As shown in FIG. 2, the guide shaft 41, the rear spring 11, the spacer 17, the lens support 7 that fixes the coil body 15 to the outer periphery, the yoke 3 that fixes the four magnets 13 to the corners 14, The front spring 9 and the frame 8 are assembled and fixed in this order.

  The guide shaft 41 is erected and fixed to the base 5, the guide shaft 41 is disposed in the recess 45 in the engaging portion 43 of the lens support 7, and the front end of the guide shaft 41 is connected to the fitting hole 42 of the yoke 3. Fit into and assemble.

When the lens support 7 is driven by autofocus, a current is passed from the controller 23 to the coil body 15 as shown in FIG. Thereby, the coil body 15 moves together with the lens support 7 forward in the optical axis direction against the elastic force of the springs 9 and 11 by the electromagnetic force generated between the coil body 15 and the magnet 13.
The control unit 23 causes a current to flow through the coil body 15 so as to move the lens support 7 to the in-focus position with the highest contrast while comparing the peaks of the high-frequency component of the contrast at the center position of the image sensor 19. As described above, since the current flowing through the coil body 15 is controlled by feeding back the contrast signal from the image sensor 19, it occurs when the drive control is performed based on the correlation between the conventional movement amount and the current value. There is no so-called hysteresis error. The systematic error is an error caused by a frictional change between the guide shaft 41 and the engaging portion 43.

  When the lens support body 7 moves forward, the lens support body 7 has a resultant force of elastic forces in the front-rear direction of the front spring 9 and the rear spring 11 and an electromagnetic force generated between the coil body 15 and the magnet 13. Stops at the position where they hang.

  Accordingly, the lens support 7 can be moved only by the electromagnetic force generated between it and the magnet 13 when the coil body 15 is energized. As shown in FIG. 5, when the lens support 7 moves, the movement of the lens support 7 is guided by engagement with two guide shafts 41.

Even after the lens support 7 is moved to the in-focus position, the engaging portion 43 is engaged with the guide shaft 41, so that the posture of the lens support 7 can be maintained and tilting can be prevented.
That is, according to the present embodiment, since the lens support 7 is moved and stopped by the guide shaft 41, the tilt of the lens support 7 that occurs when the lens support member 7 is moved and after the stop can be prevented.
According to the present embodiment, since the guide shaft 41 is fitted and held in the fitting hole 42 of the yoke 3, the assembly is easy.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention. For example, the guide shaft 41 is not limited to being provided at two locations on the outer periphery of the lens support 7, but is provided at three locations and four locations at equal intervals, and the lens support 7 has an engaging portion at a position corresponding to the guide shaft 41. 43 may be provided .
The guide shaft 41 may be arranged to penetrate the front spring 9 and fix the front end to the frame 8.
Further, the shape of the guide shaft 41 is not limited to a cylinder, and may be a prism.

DESCRIPTION OF SYMBOLS 1 Lens drive device 3 Yoke 7 Lens support body 9 Front side spring 11 Rear side spring 13 Magnet 15 Coil body 41 Guide shaft 43 Engagement part

Claims (5)

A lens support for supporting the lens, a coil body fixed to the outer periphery of the lens support, a spring for movably supporting the lens support, and an outer peripheral side of the lens support and disposed opposite the coil body A magnet and a guide shaft provided in the direction of the optical axis of the lens. When the coil body is energized, the lens support is moved to a predetermined position by balancing the electromagnetic force generated against the magnetic field of the magnet and the elastic force of the spring. A lens driving device,
The lens support has an engaging portion that engages with the guide shaft on the outer peripheral side, and the engaging portion is formed with a recess recessed on the inner peripheral side of the lens support , and the lens support is moved and stopped. The lens driving device according to claim 1, wherein the recess of the engaging portion of the lens support is engaged with the guide shaft from the inner peripheral side of the lens support .   An annular yoke having a lens support disposed on the inner periphery is provided, and springs are disposed at least one of the front and rear in the optical axis direction of the yoke, and the yoke has a polygonal shape in plan view when viewed from the optical axis direction. 2. The lens driving device according to claim 1, wherein the magnet is disposed at each corner of the yoke, and the guide shaft is disposed between the corners of the yoke.   The yoke has an inner wall extending from the outer circumferential wall and one end in the optical axis direction of the outer circumferential wall to the inner circumferential side, and one end of the guide shaft is held in the fitting hole of the inner extending portion. The lens driving device according to claim 2, wherein   A lens driving device according to any one of claims 1 to 3, an image sensor provided on the image forming side of the lens of the lens support, and a control unit, wherein the control unit has a high contrast of the image sensor. An autofocus camera characterized in that a current is passed so as to move the lens support 7 to a focus position with the highest contrast while comparing the peak of the region component.   A camera-equipped mobile terminal device, comprising the autofocus camera according to claim 4.

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