CN112987223A

CN112987223A - Lens driving device

Info

Publication number: CN112987223A
Application number: CN202110296113.0A
Authority: CN
Inventors: 陆圣
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-03-19
Filing date: 2021-03-19
Publication date: 2021-06-18
Also published as: CN115113359A; CN218917760U; CN115016092A

Abstract

The invention provides a lens driving device for adjusting focus by driving a lens through expansion and contraction of an electromechanical conversion element. The electromechanical conversion driver comprises a friction driving shaft, an electromechanical conversion element and a heavy hammer. The friction driving shaft is coupled to one end of the electromechanical transducer, and the weight for fixing is coupled to the other end of the electromechanical transducer. The configuration mode of the electromechanical conversion driver is a mode that the telescopic direction of the electromechanical conversion driver is not parallel to the optical axis of the lens; the conversion of the movement of the electromechanical conversion element in the expansion and contraction direction into the movement in the optical axis direction of the lens is realized by a conversion mechanism.

Description

Lens driving device

Technical Field

The present invention relates to a lens driving device, and more particularly to a lens driving device using an actuator of an electromechanical transducer such as a piezoelectric element.

Background

At present, cameras mounted on portable smart devices such as smartphones and smartwatches are becoming higher and higher in functionality and performance. Specifically, the present invention is directed to high-performance of a high-pixel photosensitive chip and a corresponding lens. Although the pixel size of the photo sensor chip can be reduced to some extent by the manufacturing process to reduce the camera size, the reduction of the camera size has been approaching a limit due to the limitations of the photo sensor chip and lens manufacturing process. As a lens driver or a motor occupying a certain volume of the camera for driving the lens, a voice coil motor VCM and a piezoelectric ceramic driver motor are mainly used at present. Voice Coil Motors (VCM) are widely used because they are inexpensive and mature in mass production. However, with the high pixelation of the mobile phone lens, the number of lenses of the optical lens matched with the mobile phone lens is already developed to 6 to 9 or more, and the quality of the lens is heavier; and the stroke requirements for the drive are also increasing due to the need for closer range photography. Due to structural constraints, VCM has become increasingly unable to meet market growth requirements in terms of drive force and stroke. The piezoelectric ceramic driver has the characteristics of high thrust, large stroke, small volume and the like. Therefore, it is a trend that piezoelectric ceramic drivers are adopted in portable smart devices such as smart phones and smart watches in the future. The driving principle of the piezoelectric ceramic actuator and the conventional product structure technology will be specifically described below.

The piezoelectric driving device is composed of a piezoelectric element, a weight block (also called a weight) bonded and fixed at one end of the piezoelectric element, and a friction rod (friction driving shaft) bonded at the other end. The drive principle is illustrated in fig. 1 as follows:

when a voltage having a sawtooth waveform such as a slow rise (between a-B) and a sharp fall (between B-C) shown in fig. 1 is applied to the piezoelectric element of the piezoelectric driving device, the piezoelectric element extends in the axial direction against the slow rise (between a-B) and the driving shaft fixed to the piezoelectric element moves together in the advancing direction thereof. The moving body frictionally coupled to the driving shaft moves together with the driving shaft by a frictional force.

When the voltage is in a sharp drop portion (between B and C), the piezoelectric element rapidly contracts and retreats along the axis, and the friction axis is also rapidly displaced backward. At this time, as shown in fig. 1(a3), since the inertial force of the moving body is greater than the frictional force with the drive shaft and sliding occurs, the moving body is substantially held at the position and does not move. As a result, the amount of movement of the moving body in the forward direction is a difference in the amount of movement at the time of forward and backward movements, compared to the initial state shown in fig. 1(a 1). By repeating such expansion and contraction by applying the sawtooth voltage to the piezoelectric element, the movable body can be driven in the forward direction. If a reverse sawtooth voltage is applied, a reverse drive can be achieved.

The technical scheme of the structure of the piezoelectric lens driver for the existing intelligent equipment such as mobile phones comprises the following published documents:

reference 1: japanese patent (japanese patent No. 5252260);

reference 2: japanese patent (Japanese patent No. 6024798).

Such a driver drives a moving body using a laminated piezoelectric ceramic element as an electromechanical conversion element. For example, in an image pickup device built in a mobile apparatus such as a mobile phone, this type of electromechanical conversion driver is used as a driving device for moving an optical lens in an optical axis direction to achieve miniaturization. A fixed body is bonded to one end of the piezoelectric ceramic element, a friction drive shaft body is fixed to the other end thereof, and the movable body and the friction drive shaft body are frictionally coupled to each other.

In the drive device disclosed in the above-mentioned publication, the actuator is disposed parallel to the optical axis of the optical lens, and the optical lens is moved by frictionally coupling a housing as a moving body that supports the optical lens to the friction drive shaft. In addition, in order to ensure frictional engagement with the friction bar, the movable body is pressed against the friction bar by the elastic force of the elastic body.

For example, as described in reference 1 to 2, there is proposed a lens driving device in which a piezoelectric actuator is disposed in parallel with a lens optical axis at one corner (a) of a lens frame (or holder), and a frictional coupling is formed by sandwiching a driving shaft body (or rod) of the piezoelectric actuator between a V-shaped groove formed in the lens frame and a pressing rod supported by the lens frame and pressed by a cylindrical helical pressing spring. FIGS. 2 to 4 are illustrations shown in reference 1. As shown in fig. 2-4, the piezoelectric actuators are disposed in parallel at an angle a along the same direction of the optical axis of the lens. As shown in the bottom side views of fig. 2 to 4, the thickness of the piezoelectric lens actuator in the optical axis direction corresponds to the length of the piezoelectric actuator.

In addition, reference 2 proposes a lens driving device in which a piezoelectric actuator is disposed parallel to an optical axis at one corner of a lens frame, and as shown in fig. 5 to 6, friction coupling is formed by sandwiching a driving shaft body of the piezoelectric actuator between a V-shaped planar groove formed in a lens housing and a plate spring supported by the lens housing and disposed along an outer periphery of the lens housing. The length of the piezoelectric actuator is equivalent to the thickness of the lens driving device in the optical axis direction.

Since the drive shaft of the piezoelectric actuator, the piezoelectric element, and the weight member are fixed in series, the thickness of the actuator is not less than the series length of the piezoelectric actuator, as limited by the series length of the piezoelectric actuator, in the case where the piezoelectric actuator is disposed in parallel with the optical axis as described in references 1 and 2. This is disadvantageous in the development of camera modules that require further miniaturization and thinning, such as smart phones and smart watches.

Disclosure of Invention

In order to solve the above problems, the present invention provides a lens driving device for driving a lens to adjust a focus by expansion and contraction of an electromechanical conversion element, wherein the lens driving device is characterized in that an expansion and contraction direction of the electromechanical conversion element intersects with a lens optical axis. The object of the present invention is to further miniaturize a lens driving device using an electromechanical conversion element such as a piezoelectric element with a simple structure.

The object of the present invention is to realize further miniaturization of a lens driving device driven by a piezoelectric element having a fixed structure in series by a driving shaft-piezoelectric element-weight at low cost and with a simple structure.

In order to achieve the above object, an embodiment of the present invention provides a lens driving device that performs focus adjustment by driving a lens with expansion and contraction of an electromechanical conversion element, wherein the expansion and contraction direction of the electromechanical conversion element is disposed in a non-parallel or orthogonal manner with respect to an optical axis of the lens. In the lens driving device, a friction driving shaft is fixed at one end of the electromechanical conversion element, and a fixed object is fixed at the other end.

Another embodiment of the present invention provides a lens driving device for driving a lens to adjust a focal point by expansion and contraction of an electromechanical conversion element, wherein the electromechanical conversion element is disposed in such a manner that an expansion and contraction direction thereof is non-parallel to an optical axis of the lens, preferably in such a manner that the expansion and contraction direction thereof is orthogonal to the optical axis of the lens; the orthogonal arrangement is most advantageous in reducing the thickness direction, and the non-parallel non-orthogonal arrangement is slightly less effective than the orthogonal arrangement. Compared with the prior art, when the electromechanical conversion element is configured in a mode that the stretching direction of the electromechanical conversion element is not parallel to the optical axis of the lens, the influence of the length size of the electromechanical conversion element on the thickness of the lens in the optical axis direction can be completely avoided or reduced, and the thickness of the lens module is further reduced.

The friction driving shaft body is combined with one end of the electromechanical conversion element, and the heavy hammer is combined with the other end of the electromechanical conversion element;

the lens driving device converts the movement of the electromechanical conversion element in the expansion and contraction direction into the movement of the lens in the optical axis direction through the conversion structure. The transformation structure includes:

a friction part which is composed of a spiral torsion friction spring in friction combination with the friction driving shaft and a moving body covering the spiral torsion friction spring and moving integrally with the spiral torsion friction spring; the spiral torsion friction spring is fixed with the moving body covered on the spiral torsion friction spring into a whole, and the spiral torsion friction spring is combined with the friction driving shaft through friction; compared with the prior art, the arrangement scheme of the spiral torsion friction spring can reduce the circumferential size of the lens module;

a conversion section that converts the movement in the expansion and contraction direction of the electromechanical conversion element into the movement in the optical axis direction of the lens by using an inclined surface that moves (preferably integrally formed) in synchronization with the movable body or the lens frame as a cam driving portion or a cam follower portion (as a cam driving portion when the inclined surface moves in synchronization with the movable body, and as a cam follower portion when the inclined surface moves in synchronization with the lens frame);

and an energizing spring part for always energizing the driven part and the driving part to be in pressure contact with each other by a spring force of the coil torsion energizing spring.

Wherein, when the inclined surface moves synchronously with the moving body as the cam driving part, the inclined surface forms a certain angle with respect to the telescopic direction of the electromechanical conversion element or the optical axis direction of the lens, and the lens or the lens frame is driven by the inclined surface acting on the driven part which moves synchronously (preferably integrally) with the lens or the frame thereof;

when the inclined surface and the lens frame move synchronously to serve as a cam driven part, a driving part on the moving body and the cam driven part are contacted with each other, and the driving part pushes the cam driven part to drive the lens or the lens frame;

the cam driven part and the driving part are mutually pushed by the accumulated force of an energizing spring or the driven part and the cam driving part are mutually pushed by the accumulated force of the energizing spring; preferably, the energizing part of the energizing spring is substantially parallel to the inclined surface part of the driven part of the converting structure.

Preferably, the electromechanical conversion element is a laminated piezoelectric element.

Another embodiment of the present invention provides a lens driving device in which a movable body having a cam portion is frictionally coupled to the friction drive shaft, and the movement of the movable body with the cam portion in the expansion/contraction direction of the electromechanical conversion element is converted into the movement in the lens optical axis direction. In particular, the cam portion is an inclined surface forming a certain angle with respect to the expansion and contraction direction of the electromechanical conversion element and the optical axis direction of the lens, and the optical axis direction of the lens is driven by the thrust force of the cam inclined surface as the driving portion against a driven portion integrally formed with a lens frame housing the lens. In particular, the driven portion forms an interaction force with the cam portion as the driving portion by an urging force of an energizing spring of a wound torsion spring type, and a straight arm of the energizing spring is substantially parallel to the cam slope.

Another embodiment of the present invention provides a lens driving device in which a movable body having an active portion for converting a movement of an electromechanical conversion element in an expansion/contraction direction into a movement of a lens in an optical axis direction is frictionally coupled to the friction drive shaft body. In particular, the conversion structure includes a slope portion formed integrally with the lens frame and forming a predetermined angle with respect to the expansion/contraction direction of the electromechanical conversion element or the optical axis direction of the lens as a driven portion, and the driving portion and the driven portion of the movable body are in contact with each other. The lens is driven by the driving section pressing the driven body. In particular, the driven part and the driving part are mutually energized and pressed by an energizing spring, and the energizing part of the energizing spring is approximately parallel to the inclined surface part of the driven part of the transformation structure.

Another embodiment of the present invention provides a lens driving device, wherein a friction driving rod is adhesively fixed to one end of the electromechanical transducing element, and a fixing body is fixed to the other end. The moving body having a cam is frictionally coupled to the friction drive rod, and converts the movement of the electromechanical conversion element in the expansion/contraction direction into the movement of the lens in the optical axis direction. The cam is an inclined surface forming a certain angle with respect to the expansion and contraction direction of the electromechanical conversion element and the optical axis direction of the lens, and is characterized in that the lens is driven by pressing a driven portion formed integrally with a lens housing that houses the lens. In the lens driving device, the follower portion is pressed against the cam surface by the spring member, and the pressing portion of the spring is substantially parallel to the cam surface.

The electromechanical transducer according to the present invention may be a piezoelectric element, preferably a multilayer piezoelectric element, for example, a multilayer accumulation type piezoelectric ceramic is preferable as the piezoelectric element.

The embodiment of the invention has the advantages that:

1. compared with the prior art, when the electromechanical conversion element is configured in a mode that the telescopic direction of the electromechanical conversion element is not parallel to the optical axis of the lens, the influence of the length size of the electromechanical conversion element on the thickness of the optical axis of the lens can be completely avoided or reduced, the thickness of the lens module is further reduced, and the miniaturization and thinning of the camera module are realized;

2. the friction fit of the wire spring (friction torsion spring/spiral torsion friction spring) and the contact area of the driving shaft are larger than the friction contact area of the flat spring used in the prior art, so that the abrasion caused by sliding friction is reduced, and the durability is improved;

3. the laminated piezoelectric element is used for driving, and the linear spring (friction torsion spring/spiral torsion friction spring) is used for driving the moving body under the condition that the driving direction is not parallel to the optical axis direction, particularly under the condition of orthogonality, so that the circumferential size of the lens module can be reduced compared with the prior art;

4. the pressing portion of the spring is substantially parallel to the cam surface, and the accuracy of lens drive control can be improved.

The advantages and spirit of the present invention can be further understood by the following detailed description of the invention and the accompanying drawings.

Drawings

FIG. 1 is a schematic diagram of a piezoelectric ceramic actuator in the prior art;

FIG. 2 is a front view of a prior art piezoelectric actuator;

FIG. 3 is a perspective view of a piezoelectric actuator according to the prior art;

FIG. 4 is a bottom/side view of a prior art piezoelectric actuator;

FIG. 5 is an exploded view of a prior art piezoelectric actuator;

FIG. 6 is a two-dimensional view of a prior art piezoelectric actuator;

fig. 7 is a perspective view of the configuration of a lens driving device according to an embodiment of the present invention;

fig. 8 is an exploded view (exploded view of fig. 7) of the configuration of a lens driving device according to an embodiment of the present invention;

fig. 9 is a side view (left side view in fig. 11) of the configuration of a lens driving device according to an embodiment of the present invention;

fig. 10 is a sectional view of a piezoelectric actuator unit (sectional view D-D in fig. 11) relating to the configuration of a lens driving device according to an embodiment of the present invention;

fig. 11 is a front view of the configuration of a lens driving device relating to an embodiment of the present invention;

fig. 12 is a cam portion operation diagram (a cross-sectional view C-C in fig. 11) relating to the configuration of the lens driving device according to the embodiment of the present invention; wherein the content of the first and second substances,

(A) indicating a start position that has not yet been driven (tele-photography),

(B) a drive position indicating that the image has been driven (close-up imaging);

fig. 13 is a perspective view of a moving body 501 having a cam driving part 55 according to an embodiment of the present invention;

fig. 14 is a drive voltage waveform of a lens driving device according to an embodiment of the present invention;

fig. 15 is a perspective view showing the configuration of a lens driving device according to another embodiment of the present invention;

fig. 16 is an exploded view (exploded view of fig. 15) showing the configuration of a lens driving device according to another embodiment of the present invention;

FIG. 17 is a side view (left side view in FIG. 19) showing the configuration of a lens driving device according to another embodiment of the present invention;

FIG. 18 is a sectional view of a piezoelectric actuator unit showing the configuration of a lens driving device according to another embodiment of the present invention (sectional view taken along line D-D in FIG. 19);

fig. 19 is a front view showing the configuration of a lens driving device according to another embodiment of the present invention;

FIG. 20 is a cam portion operation view (a sectional view C-C in FIG. 19) showing the configuration of a lens driving device according to another embodiment of the present invention; wherein the content of the first and second substances,

fig. 21 is a perspective view showing a movable body 502 having a driving part 155 according to another embodiment of the present invention;

fig. 22 is an enlarged perspective view of the cam follower portion 134 (cam slope) of embodiment 2;

fig. 23 shows drive voltage waveforms of a lens drive device according to another embodiment of the present invention.

Description of the symbols

10 lens holder, 11 imaging element substrate joint portion, 12 guide shaft holding portion, 13 lens rotation restricting portion, 14a, 14b drive shaft holding portion, 15 moving body rotation restricting portion, 16a, 16b piezoelectric driver holding plate mounting portion, 20 guide shaft, 30 lens frame, 31 lens housing portion, 32 guide portion, 33 rotation restricting portion, 34 follower portion, 134 cam follower portion (cam slope), 40 piezoelectric driver holding plate, 41a,41b mounting portion, 42 piezoelectric driver bonding portion, 501 moving body (with cam), 502 moving body (with driving member, without cam) 51 fitting portion, 52 friction spring housing portion, 53 rotation restricting portion, 54a, 54b friction spring contact portion, 155 driving portion, 55 cam driving portion, 56 energizing spring mounting portion, 60 friction spring, 61, 62 arm portion, 70 energizing spring, 71, 72 spring arm portion, 135 energized torsion spring mounting part, 136 energized torsion spring contact part, A lens optical axis, L lens group, IS image sensor, CB image pickup element substrate, PA piezoelectric actuator, P piezoelectric element, P1 drive shaft bonding part, P2 hammer bonding part, S friction drive shaft, W weight, W1 piezoelectric element bonding part, W2 piezoelectric actuator holding plate bonding part

Detailed Description

Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention should be understood not to be limited to such an embodiment described below, and the technical idea of the present invention may be implemented in combination with other known techniques or other techniques having the same functions as those of the known techniques.

In the following description of the embodiments, for purposes of clearly illustrating the structure and operation of the present invention, directional terms are used, but the terms "front", "rear", "left", "right", "outer", "inner", "outward", "inward", "axial", "radial", and the like are to be construed as words of convenience and are not to be construed as limiting terms.

Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

An embodiment of the lens driving device will be described below with reference to fig. 7 to 14.

The lens holder 10 includes an image pickup device substrate engagement portion 11 that engages with an image sensor substrate CB to which an image sensor IS attached, a support portion 12 of a guide post 20 that IS fixed and held in parallel with an optical axis (a), and a lens stopper portion 13 that prevents a lens frame 30 from rotating along the optical axis.

The lens frame 30 includes a lens barrel 31 for accommodating the lens group L, a guide portion 32 movably fitted to the guide post 20 in the optical axis direction, and a rotation restricting portion 33 which IS movable in the optical axis direction and engages with the lens stopper 13 to restrict rotation around the guide post 20 of the lens frame 30 and position the center of the image sensor IS in alignment with the optical axis of the lens group L.

In this way, the lens group L moves along the optical axis in a state where the center of the photosensitive chip IS aligned with the optical axis, and the distance from the photosensitive chip IS can be changed, so that the focal position of the lens group L can be aligned with the image plane of the photosensitive chip IS even if the photographing distance IS changed.

The piezoelectric actuator PA is composed of a piezoelectric element, a drive shaft S adhesively fixed to the front end face P1, a weight adhesively fixed to the rear end face, and the like.

A piezoelectric actuator holding plate 40 is fixed to a rear end face W2 of the weight W of the piezoelectric actuator PA, and holding portions 41a and 41b of the piezoelectric actuator holding plate 40 are fixed to the lens holder 10.

The piezoelectric element P expands and contracts by an amount corresponding to the amount of the applied voltage in the front-rear direction (P1-P2), and the drive shaft S is displaced in the axial direction in accordance with the expansion and contraction of the piezoelectric element S.

The drive shaft S is made of a material having a low specific gravity (for example, carbon fiber resin), and the weight W is made of a material having a high specific gravity (for example, tungsten). Since the expansion and contraction of the piezoelectric element P are performed in a short time of several microseconds, the displacement of the front end surface P1 side of the drive shaft S having a small adhesive specific gravity and a small inertial mass is suppressed, and the displacement of the rear end surface P2 side of the weight W having a large specific gravity and a large inertial mass is fixed and bonded.

Since both ends of the drive shaft S are held on the drive

shaft mounting portions

14a, 14b of the lens holder 10 movably in the axial direction, the piezoelectric driver PA is positionally mounted in such a manner that the axis of the drive shaft is orthogonal to the optical axis.

Further, the inner diameter is smaller than the outer diameter of the drive shaft S, the frictional torsion springs 60 which are wire springs are press-fitted into the drive shaft S to be frictionally engaged with each other, and the engaging portion 51 of the moving body 501 having a cam portion is engaged with the drive shaft S to be movable in the axial direction.

The moving body 501 has a friction torsion spring housing portion 52 covering the friction torsion spring 60 and friction torsion

spring arm portions

61 and 62 of the friction torsion spring 60 pressed against friction torsion

spring contact portions

54a and 54b, respectively. The friction

spring contact portions

54a and 54b are inclined surfaces having a predetermined angle with respect to the axial direction, and the moving body 501 and the friction torsion spring 60 are integrally movable by receiving a predetermined frictional force on the drive shaft S due to the elastic force of the friction torsion spring 60 and the urging force of the friction torsion

spring arm portions

61 and 62.

Further, since the frictional engagement of the wire spring (friction torsion spring) and the drive shaft has a larger contact area than that of the flat spring used in the prior art, the wear due to the sliding friction is reduced, and the durability is improved.

The moving body 501 has a rotation restricting portion 53, and is fitted to the cam member rotation restricting portion 15 of the lens holder 10, whereby the moving body 501 can be moved in the axial direction of the drive shaft s while being prevented from rotating.

The moving body 501 includes a cam driving portion 55, and the follower portion 34 is urged by an urging spring arm portion 72 of an urging spring 70 attached to an urging spring attaching portion 56, so that the follower portion 34 is always in forced contact with the cam driving portion 55, and the lens frame 30 is movable in the optical axis direction (Z direction) in conjunction with the movement of the moving body 501 in the driving axis S direction (Y direction).

When the voltage shown in fig. 14 is applied to the piezoelectric actuator PA, and the piezoelectric element P rapidly expands (contracts) when the applied voltage rapidly changes, the drive shaft S is displaced at a large acceleration, and therefore the friction torsion spring 60 easily slides, and when the applied voltage slowly changes, the piezoelectric element P slowly extends (contracts), and thus the drive shaft S is displaced at a smaller acceleration than when the applied voltage slowly changes, and the friction torsion spring 60 becomes less likely to slide.

As shown in fig. 12 a and B, the cam driving portion 55 (inclined surface) is substantially parallel to the energizing spring arm portion 72, that is, the working angle of the energizing spring 70 is hardly changed during the driver driving operation, and therefore, the difference in driving force (reciprocating difference) in the driving direction of the lens frame 30 can be reduced.

The voltage shown in fig. 14 is applied to the piezoelectric driver PA. When the applied voltage changes rapidly, the driving shaft S is displaced at a large acceleration due to rapid extension (contraction) of the piezoelectric element P, and therefore the friction torsion spring 60 slides easily, and when the applied voltage changes slowly, the driving shaft S is displaced at a small acceleration due to slow extension (contraction) of the piezoelectric element P, and thus the friction torsion spring 60 becomes less likely to slide.

The moving body 501, which IS movable integrally with the friction torsion spring 60, IS moved in a predetermined direction by a reciprocating difference in displacement acceleration of the drive shaft S caused by the applied voltage waveform, and the lens frame 30, which IS interlocked with the moving body 501, IS moved so that the distance of the lens group L from the photosensitive chip IS can be changed.

For example, the lens group L is driven forward by repeating the rapid rise and the slow fall of the applied voltage as shown in fig. (a) and the rapid rise and the rapid fall as shown in fig. (b), whereby the lens group L is driven backward.

Another embodiment of the lens driving device will be described below with reference to fig. 15 to 23.

As shown in fig. 15, 16, and 20, the lens holder 10 includes an image pickup device substrate engagement portion 11 that engages with the image sensor substrate CB to which the image sensor IS attached, a support portion 12 of the guide post 20 that IS fixed and held in parallel with the optical axis (a), and a lens stopper portion 13 that prevents the lens frame 30 from rotating along the optical axis.

Since both ends of the drive shaft S are held on the drive

shaft mounting portions

Further, the inner diameter is smaller than the outer diameter of the drive shaft S, and the torsion spring type friction torsion springs 60, which are wire springs, are press-fitted into the drive shaft S to be frictionally engaged with each other, and the engaging portion 51 of the moving body 502 is engaged with the drive shaft S to be movable in the axial direction.

As shown in fig. 17, 18, 19, 20 and 21, the movable body 502 having the driving portion 155 has a friction torsion spring housing portion 52 covering the friction torsion spring 60 and friction torsion

spring arm portions

61 and 62 of the friction torsion spring 60 pressed against the friction torsion

spring contact portions

54a and 54b, respectively. The friction

spring contact portions

54a and 54b are inclined surfaces having a predetermined angle with respect to the axial direction, and the movable body 502 and the friction torsion spring 60 are urged by the friction torsion

spring arm portions

61 and 62 by the elastic force of the friction torsion spring 60 to be integrally movable while receiving a predetermined frictional force on the drive shaft S.

The movable body 502 has a rotation restricting portion 53, and is fitted to the movable body rotation restricting portion 15 of the lens holder 10, whereby the movable body 502 can be moved in the axial direction of the drive shaft s while being prevented from rotating.

The moving body 502 includes a driving portion 155, and contacts a cam follower portion (inclined surface) 134 integrally formed with the lens frame. The energizing spring 70 is attached to the energizing torsion spring mounting part 135, and

arms

72 and 71 of the energizing spring are respectively attached to and press-contacted with the driving part 155 and the energizing torsion spring contact part 136 integrally formed with the lens frame 30. The urging force of the energizing spring 70 against the torsion force applied to the driving portion 155 and the cam follower (inclined surface) 134 causes the cam follower (134) to be always in forced contact with the driving portion 155 of the movable body 502, and the lens frame 30 can be moved in the optical axis direction (Z direction) in conjunction with the movement of the movable body 502 in the driving axis S direction (Y direction).

When the voltage shown in fig. 22 is applied to the piezoelectric actuator PA, and the piezoelectric element P rapidly expands (contracts) when the applied voltage rapidly changes, the drive shaft S is displaced at a large acceleration, and therefore the friction torsion spring 60 easily slides, and when the applied voltage slowly changes, the piezoelectric element P slowly extends (contracts), and thus the drive shaft S is displaced at a smaller acceleration than when the applied voltage slowly changes, and the friction torsion spring 60 becomes less likely to slide.

As shown in fig. 20 a and B, the cam follower (ramp) 134 is substantially parallel to the arm 72 of the energizing torsion spring, that is, the working angle of the energizing spring 70 is hardly changed during the driver driving operation, and therefore, the difference in driving force (reciprocating difference) in the driving direction of the lens frame 30 can be reduced.

The voltage shown in fig. 22 is applied to the piezoelectric driver PA. When the applied voltage changes rapidly, the driving shaft S is displaced at a large acceleration due to rapid extension (contraction) of the piezoelectric element P, and therefore the friction torsion spring 60 slides easily, and when the applied voltage changes slowly, the driving shaft S is displaced at a small acceleration due to slow extension (contraction) of the piezoelectric element P, and thus the friction torsion spring 60 becomes less likely to slide.

The movable body 502, which IS movable integrally with the friction torsion spring 60, IS moved in a predetermined direction by a reciprocating difference in displacement acceleration of the drive shaft S caused by the applied voltage waveform, and the lens frame 30, which IS interlocked with the movable body 502, IS moved so that the distance of the lens group L from the photosensitive chip IS can be changed.

The terms "first" and "second" as used herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, unless otherwise specified. Similarly, the appearances of the phrases "a" or "an" in various places herein are not necessarily all referring to the same quantity, but rather to the same quantity, and are intended to cover all technical features not previously described. Similarly, modifiers similar to "about", "approximately" or "approximately" that occur before a numerical term herein typically include the same number, and their specific meaning should be read in conjunction with the context. Similarly, unless a specific number of a claim recitation is intended to cover both the singular and the plural, and embodiments may include a single feature or a plurality of features.

The embodiments described in the specification are only preferred embodiments of the present invention, and the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the present invention. Those skilled in the art can obtain technical solutions through logical analysis, reasoning or limited experiments according to the concepts of the present invention, and all such technical solutions are within the scope of the present invention.

Claims

1. A lens driving device for adjusting a focus by driving a lens by expansion and contraction of an electromechanical conversion element, wherein the electromechanical conversion element is disposed in such a manner that an expansion and contraction direction thereof is not parallel to an optical axis of the lens.

2. The lens driving device according to claim 1, wherein the electromechanical transducing element is disposed in such a manner that a telescopic direction thereof is orthogonal to an optical axis of the lens.

3. The lens driving device according to claim 1 or 2, wherein a friction driving shaft body is coupled to one end of the electromechanical transducing element, and a weight is coupled to the other end of the electromechanical transducing element.

4. The lens driving device according to claim 3, characterized by having a conversion structure for converting a movement in a telescopic direction of the electromechanical conversion element into a movement in a lens optical axis direction: the lens driving device comprises a friction part for transmitting the movement of the electromechanical conversion element and a cam part for converting the movement direction of the friction part into the movement of the optical axis direction of the lens.

5. The lens driving device according to claim 4, wherein the friction portion includes a friction spring, a moving body, a friction driving shaft; wherein, the friction spring is fixed with the moving body into a whole, and the friction spring is combined with the friction driving shaft through friction.

6. The lens driving device according to claim 4 or 5, wherein the cam portion includes: the cam driven part and the corresponding driving part or the cam driving part and the corresponding driven part; wherein the cam driving part or the cam driven part is a slope that moves in synchronization with the moving body or the lens frame.

7. The lens driving device according to claim 6, wherein the cam follower and the driving portion are urged against each other by an energizing force of an energizing spring.

8. The lens driving device according to claim 6, wherein the driven portion and the cam driving portion are urged against each other by an energizing force of an energizing spring.

9. The lens driving device as claimed in claim 6, wherein said friction spring is selected from a helical torsion friction spring; the helical torsion friction spring is covered by a moving body fitted to the friction drive shaft, and arm portions at both ends of the helical torsion friction spring elastically contact with inclined surfaces of the moving body.

10. The lens driving device according to claim 6, wherein the cam driving portion has a slope forming a certain angle with respect to a direction of expansion and contraction of the electromechanical transducer element or a direction of the optical axis of the lens, and the cam slope acts on the driven portion formed integrally with the lens or a frame thereof to drive the lens or a lens frame.

11. The lens driving device according to claim 10, wherein the follower portion forms an interaction force with the cam driving portion by a force of an energizing spring, a straight arm of the energizing spring being substantially parallel to the inclined surface.

12. A lens driving device as claimed in claim 11, wherein the energizing spring is a torsion spring of a wound coil torsion spring type.

13. The lens driving device according to claim 6, wherein the movement of the electromechanical conversion element in the expansion/contraction direction is converted into the movement of the lens in the optical axis direction, and the movable body having the driving portion is frictionally coupled to the friction driving shaft body.

14. The lens driving device according to claim 13, wherein the conversion structure has the cam follower as a slope portion which is formed integrally with a lens frame and functions as a cam forming a certain angle with respect to a direction of extension and contraction of the electromechanical conversion element or a direction of an optical axis of the lens, and the driving portion and the cam follower on the movable body contact each other, and the driving portion pushes the cam follower to drive the lens.

15. The lens driving device according to claim 14, wherein the cam follower and the driving part are urged by being energized to each other by an energizing spring, and an energizing part of the energizing spring is substantially parallel to a slope of the cam follower.

16. The lens driving device according to claim 3, wherein the electromechanical transducing element is a laminated piezoelectric element.