JP2007093818A - Lens driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily adjust misalignment of an optical axis of a lens frame (lens) in a lens driving device. <P>SOLUTION: The lens driving device comprises: a lens frame 50 holding a lens G; a guide shaft 30 for freely movably guiding the lens frame 50 in directions of an optical axis L; a coil spring 60 for urging the lens frame 50 in a position off the optical axis L in one direction of the optical axis L; driving mechanisms 70 and 80 for driving the lens frame 50 in directions of the optical axis L; and cases 10 and 20 for holding both end parts 31 and 32 of the guide shaft 30, wherein an adjustment mechanism (an eccentric shaft part 32 of the guide shaft 30) capable of adjusting inclination of the lens frame 50 is adopted, thereby the inclination of the lens frame 50 can be properly adjusted to easily correct misalignment of the optical axis of the lens. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens driving device that moves a lens in the optical axis direction, and more particularly to a lens driving device that includes a guide shaft that guides a lens frame in the optical axis direction.

Conventional lens driving devices include a guide shaft and a detent shaft arranged in parallel with the optical axis, a lens frame supported by the guide shaft and the detent shaft so as to be movable in the optical axis direction, and a lens frame in the vicinity of the guide shaft. Are provided with a compression coil spring or the like that urges the lens in the optical axis direction (see, for example, Patent Document 1).
However, in this lens driving device, since the biasing force of the compression coil spring acts at a position deviated from the optical axis, a biasing force that tilts the lens frame acts, and the optical axis of the lens is the guide shaft. May deviate from the direction guided by (i.e., the set original optical axis direction).

Further, as other lens driving devices, a guide shaft and a detent shaft arranged parallel to the optical axis, a lens frame supported by the guide shaft and the detent shaft so as to be movable in the optical axis direction, and around the guide shaft Coil springs that are arranged to urge the lens frame in the optical axis direction, lead screws that are directly connected to the motor, nuts that are tilted and held on the lens frame and screwed into the lead screws, etc. One that drives the frame in the optical axis direction is known (see, for example, Patent Document 2).
However, in this lens driving device, although the squeak and rattle can be prevented, the urging force of the coil spring acts at a position deviated from the optical axis as in the above-described device, so that the lens frame is tilted. An urging force is applied, and there is a possibility that the optical axis of the lens is deviated from the direction guided by the guide shaft (that is, the set original optical axis direction).

Japanese Patent Laid-Open No. 05-241059 Japanese Patent Laid-Open No. 05-107438

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide lens light from the original direction to be set while simplifying the structure and reducing the size. It is an object of the present invention to provide a lens driving device that can easily correct a shaft misalignment, easily perform assembly work, improve productivity, improve yield, and the like.

  The lens driving device according to the present invention includes a lens frame that holds a lens, a guide shaft that guides the lens frame so as to be movable in the optical axis direction, and biases the lens frame in one direction in the optical axis direction at a position deviated from the optical axis. A lens driving device including an urging member, a driving mechanism for driving the lens frame in the optical axis direction, a case for holding both ends of the guide shaft, and an adjustment mechanism capable of adjusting the inclination of the lens frame, wherein the case includes: One end of the guide shaft and a base that holds the image sensor, and a cover that is coupled to the base and holds the other end of the guide shaft, the adjusting mechanism is located at the other end of the guide shaft from its axis. It includes an eccentric shaft portion formed at a position where the eccentricity is fixed, and a fitting hole formed in the cover for fitting the eccentric shaft portion.

According to this configuration, in a state where the lens frame is assembled to the guide shaft so as to reciprocate and is urged in one direction by the urging member, the optical axis of the lens held by the lens frame is at a predetermined position ( For example, when an axis deviation occurs from an axial direction set so as to be perpendicular to the imaging plane of the image sensor, the lens frame can be adjusted by appropriately adjusting the tilt of the lens frame by the adjustment mechanism. The inclination of the lens held in the lens is adjusted, and the deviation of the optical axis of the lens is easily corrected.
That is, by appropriately rotating the guide shaft, the direction of the eccentric shaft portion supported by the cover changes, so that the mounting angle of the guide shaft with respect to the base is finely adjusted. As a result, the inclination of the lens frame (lens) supported movably on the guide shaft is also adjusted, and the axial deviation of the lens optical axis is corrected. In particular, the structure is simplified by adopting an eccentric shaft portion integrally formed with the guide shaft as the adjustment mechanism.

In the above configuration, the urging member may be a coil spring that is compressed and disposed between the lens frame and the cover, and the coil spring may be disposed near the guide shaft.
According to this configuration, an unnecessary force relationship is generated because the guide shaft having the eccentric shaft portion as the adjusting mechanism is disposed in the vicinity of the coil spring that generates the biasing force that causes the inclination of the lens optical axis. As much as possible, it is possible to efficiently correct the axis deviation.

The said structure WHEREIN: The structure by which the connection part which connects the tool for performing rotation adjustment is formed in the end surface of an eccentric shaft part is employable.
According to this configuration, a tool (for example, a plus-shaped screw driver or a minus-shaped screw driver if the connecting portion is a groove formed in a + or-shape) is connected to the connecting portion and rotated. The angular position of the eccentric shaft portion, that is, the guide shaft can be easily adjusted.

  According to the lens driving device of the present invention having the above-described configuration, it is possible to easily correct the axial deviation of the lens optical axis from the original direction to be set while achieving simplification and downsizing of the structure, and assembling work Thus, it is possible to provide a lens driving device that can easily improve the productivity and the yield.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
1 to 5 show an embodiment of a lens driving device according to the present invention. FIG. 1 is a front view, and FIGS. 2 and 3 are cross-sectional views showing the inside of the lens in a state where the optical axis of the lens is deviated. 4, 4 and 5 are sectional views showing the inside of the lens with the optical axes aligned.

  As shown in FIGS. 1 to 4, the lens driving device includes a base 10 and a cover 20 as a case for defining an outer contour, a guide shaft 30 and a detent shaft 40 connected to the base 10 and the cover 20, and a guide shaft. 30 and a lens frame 50 supported movably in the optical axis direction L by the detent shaft 40, a coil spring 60 as a biasing member for biasing the lens frame 50 toward the rear in the optical axis direction L, and the lens frame 50. Are provided with a cam ring 70, a motor 80, and the like as drive mechanisms for driving the motor in the optical axis direction L.

  As shown in FIG. 3, the base 10 is formed by fitting a glass filter 11, a recess 10 a for attaching a CCD 12 as an imaging device, a joint 10 b for joining the cover 20, and one end 31 of the guide shaft 30. A fitting hole 10c for holding, a fitting hole 10d for fitting and holding one end portion 41 of the rotation prevention shaft 40, a support portion 10e for rotatably supporting the cam ring 70, and the like are provided.

  As shown in FIGS. 1 to 4, the cover 20 is fitted with a joint 20 a joined to the base 10, a circular opening 20 b allowing the lens frame 50 to protrude and project, and the other end 32 of the guide shaft 30. A fitting hole 20c, a fitting hole 20d for fitting the other end portion 42 of the rotation preventing shaft 40, a protrusion 20e for receiving the end portion 61 of the coil spring 60 on the inner side, and the like are provided.

The guide shaft 30 has one end portion 31 and the other end portion 32, has a circular cross section and is elongated in the optical axis direction L, and slides on a connecting portion 52 of a lens frame 50 described later. They are freely connected and guided in the optical axis direction L.
The one end 31 is fitted in the fitting hole 10c of the base 10 and is attached with a fitting that rotates relative to the fitting hole 10c when a force of a predetermined level or more is applied.
The other end portion 32 is formed as an eccentric shaft portion having a cylindrical shape at a position eccentric from the axis of the guide shaft 30 by a predetermined amount. Further, a linear groove 32a as a connecting portion for connecting the tool is formed in the other end portion 32 as the eccentric shaft portion.

That is, the guide shaft 30 has one end 31 fitted in the fitting hole 10 c of the base 10 and the other end 32 fitted in the fitting hole 20 c of the cover 20. And held in a state of extending in the optical axis direction L.
Here, since the end surface of the other end portion 32 is exposed from the cover 20, the guide shaft 30 can be rotated by connecting and turning a tool such as a minus screw driver to the groove 32a. It can be done.

The detent shaft 40 has one end portion 41 and the other end portion 42, has a circular cross section and is elongated in the optical axis direction L, and slides a connecting portion 53 of a lens frame 50 described later. It is connected movably to restrict rotation about the optical axis L.
That is, the non-rotating shaft 40 has one end 41 fitted in the fitting hole 10d of the base 10 and the other end 42 fitted in the fitting hole 20d of the cover 20, whereby the base 10 and the cover 20 are fitted. On the other hand, it is held in an extended state in the optical axis direction L.

  As shown in FIGS. 2 to 4, the lens frame 50 includes a cylindrical portion 51 that holds the lens G, a connecting portion 52 that protrudes from the cylindrical portion 51 and is slidably fitted to the guide shaft 30, and a cylindrical portion. 51, a U-shaped connecting portion 53 that is formed so as to protrude from 51 and is slidably connected to the detent shaft 40, an aperture stop portion 54, a follower portion 55 that receives a cam action by a cam ring 70, and an end portion 62 of the coil spring 60. The projection 56 etc. which receive are provided.

  That is, the guide shaft 30 is passed through the connecting portion 52, the detent shaft 40 is passed through the connecting portion 53, the cam ring 70 is brought into contact with the follower portion 55, and the end portion 62 of the coil spring 60 is brought into contact with the protrusion 56. As a result, the lens frame 50 is biased toward the rear in the optical axis direction L by the coil spring 60, and the rotation of the lens shaft 50 around the optical axis L is restricted by the anti-rotation shaft 40, while the axis of the guide shaft 30. It is supported so as to be slidable in the direction, and is moved in the optical axis direction L by receiving a cam action by the rotation of the cam ring 70.

As shown in FIGS. 1 to 5, the coil spring 60 is attached in a compressed state with the end 61 fitted into the projection 20 e of the cover 20 and the end 62 fitted into the projection 56 of the lens frame 50. It has been. Further, the coil spring 60 is disposed at a position deviated from the optical axis L and in the vicinity of the guide shaft 30.
That is, the coil spring 60 exerts an urging force for urging the lens frame 50 toward the rear in the optical axis direction L at a position deviated from the optical axis L, and as shown in FIG. An urging force is applied so as to be inclined with respect to the axis L.

As shown in FIGS. 3 and 5, the cam ring 70 is formed integrally with the cylindrical portion 71 and the cylindrical portion 71 that are rotatably supported by the support portion 10 e of the base 10, and performs a cam action in the optical axis direction L. A cam surface 72 formed, a gear 73 formed on the outer periphery of the cylindrical portion 71 and meshed with a drive gear 81 of a motor 80 described later are provided.
That is, the cam ring 70 is rotatably supported by the support portion 10e of the base 10, and rotates around the optical axis when the drive gear 81 rotates, so that the optical axis with respect to the lens frame 50 (the follower portion 55) is rotated. The cam action is exerted in the direction L.

The motor 80 is a DC motor or the like, and integrally has a drive gear 81 that meshes with the gear 73 of the cam ring 70 on its rotating shaft, and is fixed to the base 10.
That is, when the motor 80 rotates, a rotational force is transmitted from the drive gear 81 to the cam ring 70 so that the lens frame 50 is driven in the optical axis direction L.

Next, the assembling work and optical axis alignment of this apparatus will be described.
First, the end portions 31 and 41 of the guide shaft 30 and the detent shaft 40 are connected to the base 10 to which the glass filter 11 and the CCD 12 are fixed.
Subsequently, the cam ring 70 is rotatably attached to the base 10, and the lens frame 50 is slidably attached to the guide shaft 30 and the detent shaft 40 from the front thereof.

  Subsequently, in a state where the end portion 62 of the coil spring 60 is fitted in the projection 56 of the lens frame 50, the joining portion 20a is brought into contact with the joining portion 10b, and the other end portions 32 and 42 are fitted into the fitting holes 20c and 20d. The cover 20 is attached to the base 10 so that the protrusion 20e is fitted into the end 61 of the coil spring 60, and is fastened with screws (not shown) or the like.

  In this state, the coil spring 60 biases the lens frame 50 toward the rear in the optical axis direction L at a position deviated from the optical axis L, so that the coil spring 60 should be set as shown in FIGS. The position L ′ where the optical axis of the lens G is deviated from the state (the optical axis L of the lens G coincides with the axis extending in the direction perpendicular to the imaging plane of the CCD 12 fixed to the base 10). May come in.

Therefore, in order to adjust the optical axis L of the lens G to a position to be originally set (the optical axis L ′ in FIG. 3 coincides with the optical axis L), the lens G is provided at the other end 32 of the guide shaft 30. A tool (minus screwdriver) is connected to the groove 32a and rotated appropriately.
Then, since the other end portion 32 is an eccentric shaft portion that is deviated with respect to the axis of the guide shaft 30, the inclination of the guide shaft 30 slightly changes as shown in FIGS. 4 and 5. The slope of 50 also changes.
Therefore, the inclination of the lens frame 50 is adjusted so that the optical axis L ′ coincides with the optical axis L. In this adjustment, for example, the optical axis may be adjusted while viewing an image photographed by the CCD 12.

  As described above, a structure in which the other end portion 32 of the guide shaft 30 is formed as an eccentric shaft portion as an adjusting mechanism is adopted, and the optical axis can be aligned only by rotating the guide shaft 30 from the outside of the cover 20. Therefore, the number of parts is not increased, and the simplification of the structure, the ease of assembly work, the ease of adjustment work, and the like can be achieved.

Next, the operation of this apparatus will be briefly described. When the motor 80 rotates, the cam ring 70 rotates via the drive gear 81 and the gear 73.
When the cam ring 70 rotates, the cam surface 72 exerts a cam action on the follower portion 55 in the optical axis direction L.
Then, the lens frame 50 is guided with high accuracy by the guide shaft 30 in the optical axis direction L while being prevented from rattling by the coil spring 60 and being restricted from rotating around the optical axis L by the rotation prevention shaft 40. The CCD 12 is focused at a different position in the optical axis direction L, and a clear image is formed on the CCD 12.

  In the above-described embodiment, the configuration in which the other end portion 32 of the guide shaft 30 is formed as the eccentric shaft portion is shown as the adjustment mechanism. However, the configuration is not limited thereto, and the tilt of the lens frame 50 can be adjusted. If so, other mechanisms may be employed.

  In the above embodiment, the case where the adjustment mechanism of the present invention is adopted in the lens driving device including one lens frame 50 is shown, but the present invention is not limited to this, and two or more lens frames are used. In the lens driving device provided, the adjusting mechanism of the present invention may be employed.

  As described above, the lens driving device of the present invention can easily correct the axial deviation of the lens optical axis while achieving simplification of the structure, downsizing, etc., and can be easily assembled to improve productivity. Since the improvement of the yield is achieved, it can be applied to a portable digital camera or the like that is required to be reduced in size, and is also useful in a lens optical system that is not particularly required to be reduced in size.

It is a front view which shows one Embodiment of the lens drive device which concerns on this invention. It is sectional drawing in the direction perpendicular | vertical to the optical axis which shows the inside in the state in which the optical axis of the lens shifted | deviated. It is sectional drawing in the optical axis direction which shows the inside in the state in which the optical axis of the lens shifted | deviated. It is sectional drawing in the direction perpendicular | vertical to the optical axis which shows the inside in the state which match | combined the optical axis of the lens. It is sectional drawing in the optical axis direction which shows the inside in the state which match | combined the optical axis of the lens.

Explanation of symbols

10 Base (case)
10c, 10d fitting hole 12 CCD
20 Cover (case)
20b Openings 20c, 20d Fitting hole 20e Protrusion 30 Guide shaft (adjustment mechanism)
31 One end 32 The other end (eccentric shaft, adjustment mechanism)
32a Groove (connecting part)
40 Non-rotating shaft 41 One end portion 42 The other end portion 50 Lens frame G Lens 51 Cylindrical portion 52 Connecting portion 53 Connecting portion 54 Aperture restricting portion 55 Follower portion 56 Projection 60 Coil spring (biasing member)
61, 62 End 70 Cam ring (drive mechanism)
72 Cam surface 80 Motor (drive mechanism)
81 Drive gear

Claims (3)

A lens frame for holding the lens; a guide shaft for guiding the lens frame to be movable in the optical axis direction; a biasing member for biasing the lens frame in one direction in the optical axis direction at a position deviated from the optical axis; A lens driving device including a driving mechanism that drives the frame in the optical axis direction, a case that holds both ends of the guide shaft, and an adjustment mechanism that can adjust the inclination of the lens frame;
The case includes one end of the guide shaft and a base that holds the imaging device, and a cover that is coupled to the base and holds the other end of the guide shaft.
The adjustment mechanism includes an eccentric shaft portion formed at a position eccentric from the axis of the other end portion of the guide shaft by a predetermined amount, and a fitting formed on the cover so as to fit the eccentric shaft portion. Including a hole,
A lens driving device. The biasing member is a coil spring that is compressed and disposed between the precursor lens frame and the cover,
The coil spring is disposed in the vicinity of the guide shaft,
The lens driving device according to claim 1. On the end surface of the eccentric shaft portion, a connecting portion for connecting a tool for adjusting rotation is formed.
The lens driving device according to claim 1 or 2, wherein

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