JP2004294759A - Lens driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens driving device constituted so that a piezoelectric actuator may be hardly damaged. <P>SOLUTION: The actuator 18 is constituted by including a piezoelectric element. The actuator 18 is formed to have a long-sized sheet shape, one end part 18A is attached to the board surface of an elastic member 20, and the other end part 18B is fixed to a fixing member 22, and the actuator 18 is helically wound around a lens unit 12. The one end part 18A of the actuator 18 can be displaced in an optical axis direction L, that is, in an X direction or a Y direction shown in Fig. when a voltage is applied. Then, a driving force in the optical axis direction L is applied on the lens unit 12 by the actuator 18 through the elastic member 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lens driving device, and more particularly to a lens driving device capable of moving a lens in an optical axis direction.
[0002]
[Prior art]
A piezoelectric actuator using a piezoelectric element may be used as an actuator for moving the lens in the optical axis direction (see Patent Document 1). In general, piezoelectric actuators are vulnerable to impacts and are easily damaged. However, since the piezoelectric actuator described in Patent Document 1 is directly attached to the lens unit, there is a problem that an impact on the lens unit due to dropping or the like is directly transmitted to the piezoelectric actuator.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 10-301013
[Problems to be solved by the invention]
The present invention has been made in consideration of the above facts, and an object of the present invention is to provide a lens driving device capable of making a piezoelectric actuator difficult to break.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a lens driving device according to claim 1 includes a lens unit including one or a plurality of lenses capable of forming an image of light at a predetermined position, and the lens unit in an optical axis direction of the lens. A holding member that is movably held to the lens unit, and is fixed to a fixing position of the lens unit or the holding member, and includes a piezoelectric element that applies a force in the optical axis direction of the lens to the lens unit. The piezoelectric actuator includes an elastic member disposed between the piezoelectric actuator and the fixed position.
[0006]
In the lens driving device of the present invention, the lens unit is provided with one or a plurality of lenses capable of forming an image of light at a predetermined position, and the lens unit is held by a holding member so as to be movable in the optical axis direction of the lens. . Then, a force in the optical axis direction of the lens is applied to the lens unit by the piezoelectric actuator, whereby the lens unit moves in the optical axis direction. As described above, this piezoelectric actuator is vulnerable to impact, but an elastic member is interposed between the piezoelectric actuator and the lens unit or holding member to which the piezoelectric actuator is fixed. Therefore, even when an impact is applied to the lens unit, a part of the impact is absorbed by the elastic member. Therefore, the impact transmitted to the piezoelectric actuator can be reduced as compared with the case where one end of the piezoelectric actuator is directly attached to the lens unit, and the piezoelectric actuator can be hardly damaged.
[0007]
The lens driving device according to the present invention is characterized in that, as described in claim 2, the piezoelectric actuator is arranged at a position wound around the outer periphery of the lens unit. .
[0008]
By disposing the piezoelectric actuator in this way, the length of the piezoelectric actuator can be increased, and the displacement amount of the entire piezoelectric actuator can be increased.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
Hereinafter, a first embodiment of a lens driving device according to the present invention will be described with reference to the drawings. The lens driving device of the present invention is applicable, for example, when moving the lens for lens focus adjustment and zooming.
[0010]
As shown in FIGS. 1 and 2, the lens driving device 10 according to the present embodiment includes a lens unit 12, a holding member 14, an outer member 16, and an actuator 18.
[0011]
The lens unit 12 includes one or a plurality of lenses 12B and a cylindrical lens barrel 12A that covers a side surface of the lens 12B.
[0012]
A plate-like elastic member 20 having elastic force is attached to the side surface of the lens barrel 12A in a direction perpendicular to the optical axis L of the lens 12B.
[0013]
The outer member 16 is disposed at a position spaced apart from the lens unit 12 on the side surface of the lens unit 12 by a predetermined distance. The outer member 16 is composed of, for example, a casing in which the lens unit 12 is incorporated, a member fixed to the casing, and the like. The outer member 16 is fixed at a predetermined position, and the lens unit 12 can be moved relative to the outer member 16.
[0014]
The holding member 14 is constituted by two rectangular plate-like elastic plates 14A and 14B which are elastic and have a predetermined distance apart in parallel in the optical axis L direction. One end of each of the elastic plates 14A and 14B is fixed to the fixing position P of the outer member 16 in a direction in which the plate surface is orthogonal to the optical axis L of the lens 12B. The other ends of the elastic plates 14A and 14B are attached to the side surface of the lens unit 12. The elastic plates 14A and 14B function as parallel links to the lens unit 12, hold the lens unit 12, and suppress the inclination of the optical axis L when the lens unit 12 moves in the optical axis L direction.
[0015]
The actuator 18 includes a piezoelectric element. The actuator 18 has a long plate shape, one end 18 </ b> A is attached to the plate surface of the elastic member 20, and the other end 18 </ b> B is fixed to the fixing member 22 and spirally wound around the lens unit 12. It is made into a shape. The fixing member 22 is disposed outside the lens unit 12 like the outer member 16, and the lens unit 12 is movable relative to the fixing member 22. The outer member 16 may be configured integrally. The actuator 18 is configured such that one end portion 18A can be displaced in the optical axis L direction, that is, the X direction or the Y direction shown in FIG. As a result, the actuator 18 applies a driving force in the direction of the optical axis L to the lens unit 12 via the elastic member 20.
[0016]
Note that the elastic member 20 is capable of absorbing this impact when an impact (impact force enough to damage the actuator 18) is applied to the lens unit 12. On the other hand, the force applied to the elastic member 20 by the displacement of the actuator 18 in the direction of the optical axis L is transmitted to the lens unit 12 with almost no absorption of this force. Is set.
[0017]
Next, the operation of this embodiment will be described.
[0018]
When driving the lens driving device 10, a predetermined voltage is applied to the actuator 18 to displace the actuator 18. Accordingly, the one end 18A moves in the X direction, and the lens unit 12 to which the one end 18A is fixed can be moved in the optical axis L direction.
[0019]
When an impact is applied to the lens unit 12 due to the drop of the lens driving device 10 or the like, the impact is first directly transmitted to the elastic member 20. The elastic member 20 has an elastic force and absorbs a part of the transmitted impact. Since the impact on the actuator 18 is transmitted through the elastic member 20, this impact is smaller than the impact transmitted directly from the lens unit 12.
[0020]
Therefore, according to the lens driving device 10 of the present embodiment, the actuator 18 can be made less likely to be damaged than when the one end 18A of the actuator 18 is directly attached to the lens unit 12.
[0021]
The actuator 18 is not limited to the above. For example, as shown in FIG. 3 (A), a multilayer piezoelectric element is used as the actuator 18, or as shown in FIG. 3 (B), a spiral-shaped piezoelectric element formed by winding a band-shaped piezoelectric element around a coil spring. An element can also be used. By using a piezoelectric element as in the present embodiment, a simple structure can be achieved as compared with the case of using a driving force such as a motor.
[0022]
Moreover, although this embodiment demonstrated the example which comprised the holding member 14 by elastic board 14A, 14B, the holding member 14 can also be comprised by one elastic member. In particular, by constituting the two elastic plates 14A and 14B, these function as parallel links, and the inclination of the optical axis L can be prevented.
[0023]
Further, in the present embodiment, an example in which the holding member 14 is configured with a member having elasticity is described, but the holding member 14 is not necessarily configured with a member having elasticity. In particular, by configuring with a member having elasticity, it is not necessary to provide a movable structure by providing a joint or the like at the attachment portion of the holding member 14 to the outer member 16 or the elastic member 20, and a simple configuration can be obtained. it can.
[0024]
In the present embodiment, the example in which the elastic member 20 is attached to the lens unit 12 has been described. However, the elastic member 20 may be configured integrally with the holding member 14 as shown in FIG. Thus, by constituting the elastic member 20 integrally with the holding member 14, the number of parts can be reduced.
[0025]
Further, the one end portion 18 </ b> A of the actuator 18 can be directly attached to the holding member 14. In this case, the holding member 14 having an elastic force also serves as the elastic member 20.
[0026]
In this embodiment, the elastic member 20 is provided only on the one end portion 18A side of the actuator 18 on the lens unit 12 side. However, a similar elastic member is disposed on the other end portion 18B side, and the other end portion 18B is provided. It can also be fixed to the fixing member 22 via this elastic member. Thus, by fixing the other end portion 18B to the fixing member 22 via the elastic member, the impact from the fixing member 22 can also be absorbed, and the actuator 18 can be made more difficult to break.
[Second Embodiment]
Next, a second embodiment will be described. About this embodiment, the same code | symbol is attached | subjected about the part similar to 1st Embodiment, and detailed description is abbreviate | omitted.
[0027]
As shown in FIG. 5, the lens driving device 30 of this embodiment includes a lens unit 12, an elastic member 20, guide poles 26 </ b> A and 26 </ b> B, and an actuator 28.
[0028]
The guide poles 26A and 26B are cylindrical rods, and are arranged at symmetrical positions on both sides of the lens unit 12 along the optical axis L of the lens 12B.
[0029]
Holding members 24 and 25 and ribs 40 are provided on the side surface of the lens unit 12. The holding member 24 is configured integrally with the lens barrel 12A and protrudes from the side surface of the lens unit 12, and has a cylindrical shape with a guide pole 26A inserted through the center, and moves along the guide pole 26A. The cylinder portion 24B is made possible. The holding member 25 is provided on the side opposite to the holding member 24 on the side surface of the lens unit 12. The holding member 25 is formed with a notch 25A capable of sandwiching a part of the side surface of the guide pole 26B, and the lens unit 12 is attached to the guide pole 26B so as to be movable along the guide pole 26B. The elastic member 20 is attached to the lower surface of the rib 40.
[0030]
The actuator 28 has a long plate shape, one end 28 </ b> A is attached to the plate surface of the elastic member 20, and the other end 18 </ b> B is fixed to the fixing member 22. The actuator 28 is configured such that one end portion 28A can be displaced in the optical axis L direction, that is, the X direction or the Y direction shown in FIG. As a result, the actuator 28 applies a driving force in the direction of the optical axis L to the lens unit 12 via the elastic member 20.
[0031]
Next, the operation of this embodiment will be described.
[0032]
Since the action when driving the lens driving device 30 is the same as that of the first embodiment, the description thereof is omitted.
[0033]
When an impact is applied to the lens unit 12 due to a drop of the lens driving device 30 or the like, the impact is first transmitted to the elastic member 20. The elastic member 20 has an elastic force and absorbs the transmitted impact. Since the impact on the actuator 18 is transmitted through the elastic member 20, this impact is smaller than the impact transmitted directly from the lens unit 12. Further, since the impact from the fixing member 22 is similarly absorbed by the elastic member 32, the impact transmitted to the actuator 28 is smaller than the impact directly transmitted from the fixing member 22. Therefore, the lens driving of this embodiment is performed. The device 30 can also prevent the actuator 28 from being damaged.
[0034]
The actuator 28 is not limited to the above. It is also possible to use a laminated piezoelectric element or a spiral-shaped piezoelectric element formed by winding a band-shaped piezoelectric element around a coil spring (see FIG. 3). By using a piezoelectric element as in the present embodiment, a simple structure can be achieved as compared with the case of using a driving force such as a motor.
[0035]
Alternatively, the elastic member 20 can be attached to the holding member 24, and the one end 28 </ b> A of the actuator 28 can be attached to the holding member 24 via the elastic member 20.
[0036]
In this embodiment, the elastic member 20 is provided only on the one end portion 28A side of the actuator 28 on the lens unit 12 side. However, a similar elastic member is disposed on the other end portion 18B side, and the other end portion 28B is provided. It can also be fixed to the fixing member 22 via this elastic member. Thus, by fixing the other end portion 28B to the fixing member 22 via the elastic member, the impact from the fixing member 22 can also be absorbed, and the actuator 28 can be made more difficult to break.
[0037]
The lens driving devices 10 and 30 of the first and second embodiments can be used for lens focus adjustment and zooming as shown in FIG. The digital camera 70 includes a lens barrel 72 that can be extended to the front, and a shutter button 74 on the upper surface. The lens driving devices 10 and 30 can drive the lens barrel 72 or a focus adjustment lens unit (not shown) incorporated in the lens barrel 72. FIG. 7 shows a schematic block diagram of the digital camera 70. The digital camera 70 includes an operation unit 82, an LCD 84, a CPU 86, a driver circuit 88, a media I / F 90 (accessible to the smart media 96), a built-in memory 92, a shutter button 74, and a communication I / F 94. The lens driving devices 10 and 30 are connected to the driver circuit 88 and are driven based on a signal from the driver circuit 88.
[0038]
The lens driving devices 10 and 30 of the first and second embodiments can also be applied to a camera-equipped mobile phone. In this case, an amplifier or AD converter can be included inside the camera phone.
[0039]
【The invention's effect】
As described above, according to the lens driving device of the present invention, the elastic member is interposed between the piezoelectric element and the lens unit, and the impact applied to the lens unit is absorbed by the elastic member. The impact transmitted to the element can be made smaller than the impact transmitted directly from the lens unit, and the piezoelectric element can be made less likely to be damaged than when the piezoelectric element is directly attached to the lens unit.
[Brief description of the drawings]
FIG. 1 is a perspective view of a lens driving device according to a first embodiment.
FIG. 2 is a top view of the lens driving device according to the first embodiment as viewed from the optical axis direction of the lens.
FIG. 3 is a side view showing a modification of the actuator used in the first embodiment.
FIG. 4 is a top view illustrating a modification of the lens driving device according to the first embodiment.
FIG. 5 is a perspective view showing a modification of the lens driving device according to the second embodiment.
FIG. 6 is a perspective view of a digital camera to which the present invention is applied.
FIG. 7 is a schematic block diagram of a digital camera to which the present invention is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10, 30 Lens drive device 12B Lens 12 Lens unit 12A Lens barrel 14, 24, 25 Holding member 18, 28 Actuator (piezoelectric element)
18A, 28A One end (one end)
20 Elastic member 25 Holding member 28A One end L Optical axis

Claims (2)

A lens unit including one or more lenses capable of focusing light on a predetermined position;
A holding member that holds the lens unit movably in the optical axis direction of the lens;
A piezoelectric actuator that is fixed at a fixed position of the lens unit or the holding member, and that acts on the lens unit in the optical axis direction of the lens, and includes a piezoelectric element;
An elastic member disposed between the piezoelectric actuator and the fixed position;
A lens driving device. The lens driving device according to claim 1, wherein the piezoelectric element is disposed at a position wound around an outer periphery of the lens unit.

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