JP2009254058A - Actuator, actuator device, and variable lens unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actuator having a fixing structure which can produce a displacement and a generating force efficiently in an arcuate actuator with one end fixed and to provide an actuator device and a variable lens unit using the actuator. <P>SOLUTION: An actuator 1 includes an arcuate piezoelectric element P having a fixed end 2 and a free end 6, and a fixing member 20 for fixing the piezoelectric element so that a relation θA<θB is satisfied, assuming the central angle of the free length on the outer circumferential side of the piezoelectric element P to be θA and the central angle of the free length on the inner circumferential side of the piezoelectric element P to be θB. Consequently, a displacement at the free end 6 can be increased as compared with a case where θA=θB. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an actuator provided with an arc-shaped piezoelectric element, an actuator device including a plurality of the actuators, and a variable lens device.

  As a distance variable means for changing the distance between two lenses and a tilt variable means for changing the tilt of the lens, an annular actuator composed of an arc-shaped divided ceramic body or a divided bimorph body divided into a plurality of circumferential directions has been proposed. (See Patent Document 1). In these actuators, the center part of the divided ceramic body and the divided bimorph body is fixed.

JP 2000-48382 A (paragraphs [0038] to [0051], FIGS. 6 and 8)

  The above-mentioned patent document describes a structure in which the central part of the arc-shaped divided ceramic body and the divided bimorph body is fixed, but does not describe the case of fixing one end. When one end of the arc-shaped divided actuator is fixed and used, it is conceivable to simply fix it along the radial direction.

  However, in such a configuration, there is a difference between the free length on the inner diameter side and the free length on the outer diameter side, and the actuator plane is curved from one end to the other end in the actuator plane. However, there is a problem that bending in an oblique direction occurs, and a desired amount of displacement cannot be obtained at the tip of the other end.

  In view of the circumstances as described above, an object of the present invention is to provide an actuator, an actuator device, and a variable lens device having a fixing structure capable of obtaining an efficient displacement amount and generating force when one end of an arcuate actuator is fixed. It is to provide.

In solving the above problems, the actuator according to the present invention is:
An arc-shaped piezoelectric element having a first end that is a fixed end and a second end that is a free end;
A fixing member that fixes the first end so that θA <θB, where θA is the center angle of the outer peripheral free length of the piezoelectric element and θB is the center angle of the inner free length of the piezoelectric element It comprises.

  In the present invention, the first end of the piezoelectric element is fixed by the fixing member so that θA <θB. As a result, the outer circumferential side free length and the inner circumferential side free length of the piezoelectric element approximate to each other, so that the bending force that bends in an oblique direction with respect to the main surface of the piezoelectric element can be reduced. The amount of displacement can be obtained efficiently.

  In the actuator according to the present invention, the θB can be 160 degrees or more and 190 degrees or less, and the θA can be 110 degrees or more.

  Thereby, the amount of displacement of the free end can be made larger than when the fixed end of the piezoelectric element is fixed so that θA = θB.

  Further, by setting θB to 170 degrees and θA to 120 degrees, it is possible to obtain an actuator that has a higher displacement and generated force than the fixed structure in which θA = θB.

An actuator device according to another aspect of the present invention is
Arc-shaped first and second piezoelectric elements each having a first end that is a fixed end and a second end that is a free end;
When the central angle of the outer peripheral free length of the first and second piezoelectric elements is θA, and the central angle of the inner peripheral free length of the first and second piezoelectric elements is θB, θA <θB is satisfied. And first and second fixing members for fixing the first end portions of the first and second piezoelectric elements, respectively.

  As a result, the outer circumferential side free length and the inner circumferential side free length of the piezoelectric element approximate to each other, so that the bending force that bends in an oblique direction with respect to the main surface of the piezoelectric element can be reduced. The amount of displacement can be obtained efficiently.

  In the actuator device according to the present invention, the second end portion of the first piezoelectric element faces the first end portion of the second piezoelectric element, and the second end portion of the second piezoelectric element. The end portion of the first piezoelectric element can be configured to face the first end portion of the first piezoelectric element.

  Thereby, the area occupied by the piezoelectric actuator device can be reduced, and a thin and small piezoelectric actuator device with a large displacement can be provided.

A variable lens device according to another aspect of the present invention is:
Arc-shaped first and second piezoelectric elements each having a first end that is a fixed end and a second end that is a free end;
When the central angle of the outer peripheral free length of the first and second piezoelectric elements is θA, and the central angle of the inner peripheral free length of the first and second piezoelectric elements is θB, θA <θB is satisfied. First and second fixing members for fixing the first ends of the first and second piezoelectric elements, respectively,
A lens that is supported by the second end of the first piezoelectric element and the second end of the second piezoelectric element, and is deformed or displaced by driving the first and second piezoelectric elements; It comprises.

  Thereby, it is possible to provide a variable lens device having a large amount of displacement or deformation of the lens.

  As described above, according to the present invention, it is possible to increase the amount of displacement of an actuator including an arc-shaped piezoelectric element with one end fixed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  (Actuator and actuator device)

  An actuator and an actuator device according to an embodiment of the present invention will be described with reference to FIGS. The actuator in this embodiment is incorporated in a variable focus lens device using a liquid lens, for example, and used to adjust the focus of the liquid lens.

  FIG. 1 is a schematic plan view of the actuator device. FIG. 2 is a schematic sectional view taken along line AA ′ of FIG. FIG. 3 is a schematic plan view of the divided actuator constituting the actuator device shown in FIG.

  As shown in FIGS. 1 and 2, the actuator device 70 has a substantially annular shape having a through hole 10 at the center. The inner circumferential circle of the actuator device 70 that forms the substantially circular through-hole 10 and the outer circumferential circle that forms the outer circumference of the substantially circular actuator device 70 are concentric circles. For example, when the actuator device 70 is applied to the variable focus lens device, the liquid lens is located in a region corresponding to the through hole 10.

  The actuator device 70 is composed of two divided actuators 1 (first actuator and second actuator) divided in the circumferential direction. In this embodiment, each divided actuator 1 has the same configuration.

  Each divided actuator 1 includes an arc-shaped piezoelectric element P having a fixed end 2 (first end) and a free end 6 (second end), and a fixed that fixes the fixed end 2 of the piezoelectric element P. Member 20.

  The free end 6 of one divided actuator 1 (piezoelectric element P) faces the fixed end 2 of the other divided actuator 1 (piezoelectric element P), and the free end of the other divided actuator 1 (piezoelectric element P). 6 faces the fixed end 2 of the one split actuator (piezoelectric element P). In the present embodiment, the fixed ends 2 of the two divided actuators 1 (piezoelectric elements P) are arranged symmetrically with respect to the central portion of the actuator device 70.

  A through hole 10 (accommodating portion) for accommodating a lens as a movable member is formed between the two divided actuators 1 (piezoelectric element P).

  The fixing member 20 is for fixing the piezoelectric element P to another member, and is attached to the fixing region R1 indicated by hatching in FIGS. 1 and 3 of the piezoelectric element P by adhesion or the like. In the present embodiment, the fixed region R1 has a substantially triangular planar shape. The region R2 other than the fixed region R1 of the piezoelectric element P is a movable region that can be deformed or displaced when a voltage is applied to the piezoelectric element P. Details of the boundary 7 between the fixed region R1 and the movable region R2 will be described later.

  As shown in FIG. 3, the piezoelectric element P has a bimorph structure including a pair of piezoelectric bodies 3 and 5 having electrode surfaces formed on both surfaces, and a metal plate 4 interposed between the pair of piezoelectric bodies 3 and 5. have. As another bimorph structure, a structure such as a laminated piezoelectric bimorph or an integrally sintered laminated bimorph can be used.

  The laminated piezoelectric bimorph structure is composed of a pair of piezoelectric bodies having electrode surfaces formed inside and on both sides, and a metal plate interposed between the pair of piezoelectric bodies, and can drive the piezoelectric bimorph with a smaller voltage. . The integrally sintered laminated bimorph structure is one in which the piezoelectric sintered body itself generates bending displacement.

  As shown in FIGS. 1 and 3, the actuator device 70 includes an inner circumferential circle having a radius R <b> 1 (hereinafter referred to as an inner diameter R <b> 1) that forms a substantially circular through hole 10 and an outer circumference of the substantially circular actuator 70. An outer peripheral circle having a radius R2 (hereinafter referred to as an outer diameter R2) is formed. In the present embodiment, the outer diameter R2 is 13.8 mm, the inner diameter R1 is 7.2 mm, and the thickness is about 600 μm (micrometer). The outer diameter R2, the inner diameter R1, and the thickness are not limited to the above example.

  As shown in FIG. 3, the movable region R <b> 2 of the piezoelectric element P constituting the split actuator 1 has an outer peripheral side free length of the central angle θA and an inner peripheral side free length of the central angle θB. The fixed region R1 of the piezoelectric element P is set such that the central angle θB of the inner peripheral side free length is larger than the central angle θA of the outer peripheral side free length. The boundary 7 between the fixed region R1 and the movable region R2 is a straight line, but is not limited thereto.

  In the present embodiment, θB is not less than 160 degrees and not more than 190 degrees, and θA is not less than 110 degrees. Specifically, in this embodiment, θB is 170 degrees and θA is 120 degrees.

  In this way, by setting the movable region R2 of the piezoelectric element P so that the center angle θB of the inner circumferential free length is larger than the center angle θA of the outer circumferential free length, θA and θB can be obtained as described later. Compared with the case where it is the same, a high displacement amount can be obtained at the free end 6.

  Hereinafter, the relationship between the central angles θA and θB and the displacement amount and generated force of the piezoelectric element will be described with reference to FIGS. 5 to 9 and the effect obtained by setting θA <θB as in this embodiment will be described.

  FIG. 5 shows the central angle of the outer peripheral free length that fixes the central angle θB of the inner peripheral free length of the divided actuator in the present embodiment shown in FIG. This is a simulation result in which the displacement amount U1 and the generated force F1 at the operating point are calculated by changing the value of θA in the range of 110 degrees to 170 degrees. As shown in FIG. 3, the action point 30 is set at the outer peripheral end of the divided actuator 1 on the free end 6 side.

  FIG. 6 is a schematic plan view of a divided actuator 100 as a comparative example. The substantially annular actuator 100 includes a divided actuator 101 divided into two in the circumferential direction. The split actuator 101 has a fixed end 102 at one end and a free end 106 at the other end. The action point 130 is an outer peripheral end portion of each of the two divided actuators 101 on the free end 106 side. The boundary 107 between the fixed region R1 and the movable region R2 of the divided actuator 101 in the comparative example is a line connecting a point on the inner circle and a point on the outer circle at the central angle θC of the divided actuator 101. In other words, the boundary line 107 in the divided actuator 101 of the comparative example is that in the case of θC = θB = θA, and the boundary line 107 is along the radial direction of the actuator 100.

  FIG. 7 shows simulation results of the displacement U2 and the generated force F2 calculated by changing the angle θC in the range of 60 degrees to 270 degrees in the divided actuator 101 as the comparative example shown in FIG.

  8 shows the displacement amount U1 and the generated force F1 in the divided actuator 1 of the present embodiment shown in FIG. 5, and the displacement amount U2 and the generated force F2 in the divided actuator 101 of the comparative example shown in FIG. This is a graph plotted and compared. In FIG. 8, the displacement U2 and the generated force F2 in the divided actuator 101 of the comparative example are plotted when the angle θC is changed in the range of 90 degrees to 170 degrees.

  9 shows the product UF1 of the displacement U1 and the generated force F1 in the divided actuator 1 of the present embodiment shown in FIG. 5, and the product of the displacement U2 and the generated force F2 in the divided actuator 101 of the comparative example shown in FIG. It is the graph which compared UF2.

  Here, the configuration and characteristics of a general strip-shaped and trapezoidal-type bimorph actuator will be described with reference to FIGS.

  10A is a plan view and a cross-sectional view of a strip-shaped actuator and FIG. 10B is a trapezoidal bimorph actuator. FIG. 11 is a cross-sectional view showing driving of the bimorph actuator when no voltage is applied and when the voltage is applied. (A) shows no voltage application, and (b) and (c) show voltage application. FIG. 12 is a graph showing the relationship between the amount of displacement and the generated force at the point of action of the actuator having a strip or trapezoidal bimorph structure. Here, as shown in FIG. 4A, the displacement amount U0 (um) is the degree of displacement at the point of application when a voltage is applied when no external force is applied to the actuator 1 (201, 202). It is shown. The generated force F0 (gf) indicates the force generated at the point of action when the divided actuator 1 (201, 202) cannot be displaced during voltage application.

  As shown in FIGS. 10 (a) and 10 (b), the actuators 201 and 202 having a rectangular or trapezoidal bimorph structure, which are general shapes, are fixed at one end by a fixing member 220 and free at the other end. It is the end. The actuators 201 and 202 are configured by arranging a pair of piezoelectric bodies 203 and 205 so as to sandwich the metal member 204 between both sides, and have a free length L which is the length of a free end. The action point is located at the free ends of the actuators 201 and 202.

  As shown in FIG. 11, the piezoelectric body 203 has a piezoelectric layer 223 and an electrode layer 213, and the piezoelectric body 205 has a piezoelectric layer 215 and an electrode layer 225. Each of the two piezoelectric layers 223 and 215 is polarized in the thickness direction. In the parallel type in which the polarization directions are the same, as shown in FIG. 11B, by applying a positive voltage to the electrode layers 213 and 225 and a negative voltage to the metal plate 204, the upper piezoelectric layer 223 contracts due to the piezoelectric lateral effect, and the lower piezoelectric layer 215 extends, and as a result, as a whole bends upward. On the other hand, as shown in FIG. 11C, when a negative voltage is applied to the electrodes 213 and 225 and a positive voltage is applied to the metal plate 204, the lower piezoelectric layer 215 is contracted by the piezoelectric lateral effect, As a result, the piezoelectric layer 223 is bent downward as a whole.

  As shown in FIG. 12, in the straight bimorph actuator with the free length L not curved as described above, the relationship between the amount of displacement applied to the free end and the generated force and the generated force is large. There is a tendency that the generated force decreases as the generated force decreases, and the amount of displacement increases as the generated force decreases. When used as an actuator, it is desirable that both the displacement and the generated force be large.

  On the other hand, in an annular actuator composed of a plurality of divided actuators divided in the circumferential direction, a difference occurs between the inner peripheral side free length and the outer peripheral side free length in the split actuator, and further from one end to the other end. Has a curved shape in the actuator plane, the bending in the oblique direction occurs with respect to the actuator plane. For this reason, if the boundary line 107 between the fixed region R1 and the movable region R2 is simply set along the radial direction as in the divided actuator 101 of the comparative example shown in FIG. 6, a desired amount of displacement and generated force cannot be obtained. Will occur. As shown in FIG. 7, when the boundary line 107 is set along the radial direction as in the divided actuator 101 of the comparative example, the amount of displacement becomes maximum when the angle θC is around 170 degrees, and the angle θC is larger than that angle. It tends to decrease as it becomes larger or smaller. In addition, the generated force tends to decrease as the angle θC increases.

  Thus, in the arc-shaped split actuator 101 according to the comparative example, in the range where the angle θC is smaller than 170 degrees, the generated force tends to decrease as the displacement amount increases, and the angle θC is 170 degrees. In a larger range, both the displacement amount and the generated force tend to decrease, and the relationship between the displacement amount and the generated force varies depending on the angle θC.

  In the present embodiment, in the divided actuator 101 of the comparative example, the central angle θB of the inner circumferential free length is fixed at 170 degrees in consideration of the maximum displacement when the angle θC is 170 degrees, and the outer circumference The displacement U1 and the generated force F1 were calculated by changing the value of the central angle θA of the side free length in the range of 110 to 170 degrees.

  As a result, as shown in FIG. 5 and FIG. 8, compared with the divided actuator 101 of the comparative example, the divided actuator 1 in the present embodiment uses the central angle θA of the outer peripheral side free length as the central angle of the inner peripheral side free length. By setting it smaller than θB, a large displacement amount could always be obtained. Further, as can be seen from FIG. 8, in the comparative example and the present embodiment, the generated force is substantially the same, exactly the same at an angle of 150 degrees or more, and as the angle becomes smaller than 150 degrees, the generated force in the present embodiment is It tends to be slightly smaller than the comparative example.

  As shown in FIG. 9, even when the product of the displacement and the generated force is compared, the divided actuator 1 in this embodiment has a higher value than the divided actuator 101 in the comparative example. As shown in FIG. 9, the product of the amount of displacement and the generated force is maximized when θA is 120 degrees in both the comparative example and this embodiment.

  As described above, the amount of displacement depends on the setting of the central angle θA of the outer peripheral side free length and the central angle θB of the inner peripheral side free length of the piezoelectric element, in other words, the setting of the boundary line 7 between the fixed region R1 and the movable region R2. It can also be seen that the generated force, particularly the amount of displacement, changes greatly. As in this embodiment, when θB is 170 degrees, it is possible to obtain a larger amount of displacement than in the comparative example by setting θA to a value that is not less than 110 degrees and smaller than 170 degrees. Furthermore, by setting θA to 120 degrees, the product of the displacement amount and the generated force is maximized when θA is 120 degrees, so that both the displacement amount and the generated force can be increased.

  Further, the present invention is not limited to the case where θB is 170 degrees, and even when θB is 160 degrees or more and 190 degrees or less, θB is 170 degrees or less by setting θA to a value smaller than 110 B or more. The displacement amount and the generated force change have almost the same tendency, and a high displacement amount can be obtained as compared with the comparative example.

  In the above-described embodiment, the annular actuator is configured by two semicircular arc-shaped divided actuators. However, the annular actuator is formed by using three subarc-shaped divided actuators having a central angle larger than 90 degrees. It may be configured. In this case, three arcuate actuators can be arranged at equiangular intervals. Also in this case, as a fixing structure of the subarc-shaped split actuator, the central angle θB of the inner circumferential side free length is made larger than the central angle θA of the outer circumferential side free length, so that θA and θB are equal to each other. Thus, a high displacement amount can be obtained.

  As described above, in the present embodiment, when fixing the arc-shaped divided actuator, θA <θB, where θA is the central angle of the outer peripheral free length and θB is the central angle of the inner free length. Is set as follows. Thereby, the inner circumferential side free length and the outer circumferential side free length are approximated, and a larger displacement can be obtained as compared with the case of θA = θB.

  (Variable lens device)

  A variable focus lens device as a variable lens device using the actuator 1 will be described with reference to FIG.

  FIG. 13 is an exploded perspective view of the variable focus lens device.

  As shown in FIG. 13, the variable focus lens device 50 includes the actuator device 70 of the above-described embodiment and the variable focus lens 60. The fixing member 20 for fixing the divided actuator 1 is bonded and fixed to the container 45 of the variable focus lens 60.

  The varifocal lens 60 has a container 45 having an annular bottom surface 44 and a side wall on the outer periphery thereof, a circular transparent plate 42 and a transparent elastic member that are spaced apart from each other corresponding to the central space of the container 45. A film 41 and an annular elastic film 46 provided opposite to and spaced from the annular bottom surface 44 are provided. Furthermore, a fluid 43 made of transparent silicone oil is sealed in a space formed by the container 45, the transparent plate 42, the transparent elastic film 41, and the elastic film 46. A hollow portion formed at the center of the container 45 functions as a lens hole 340. The lens hole 340, the through hole 10 located in the center of the actuator device 70, the transparent plate 42, and the transparent elastic film 41 are arranged coaxially with each other. In addition, the liquid lens unit 40 is configured by the transparent plate 42, the transparent elastic film 41, and the fluid 43. The liquid lens portion 40 is supported or in contact with the free end 6 of each divided actuator 1 and is movable with the displacement of the free end 6.

  In the variable focus lens 60, when a voltage is applied to the actuator device 70, the transparent plate 42 moves in the optical axis direction as the actuator device 70 is displaced. Thereby, the pressure of the fluid 43 enclosed in the space formed by the transparent plate 42, the transparent elastic film 41, and the container 45 varies. Due to this pressure fluctuation, the transparent elastic film 41 is deformed, and the curvature of the irregular shape of the elastic film 41 changes. Using this change in curvature, the focal position of the liquid lens unit 40 varies, and the focus can be adjusted.

  Since the varifocal lens device 50 according to the present embodiment includes the actuator device 70 according to the present invention, the movable range of the liquid lens unit 40 is widened so that the focal length adjustment range can be expanded. Become.

  In the actuator device 70 according to the present embodiment, the free end 6 of one divided actuator 1 (piezoelectric element P) faces the fixed end 2 of the other divided actuator 1 (piezoelectric element P). The free end 6 of the divided actuator 1 (piezoelectric element P) faces the fixed end 2 of the one divided actuator (piezoelectric element P). Thereby, the area occupied by the piezoelectric actuator device can be reduced, and a thin and small piezoelectric actuator device with a large displacement can be provided.

  The actuator device 70 constituting the variable focus lens device 50 has a through-hole 10 for accommodating a lens (liquid lens portion 40) as a movable member between the two divided actuators 1 (piezoelectric elements P). (Accommodating part) is formed. Thereby, a lens can be arrange | positioned corresponding to the through-hole of a center part, and a through-hole is suitable for use as an optical path.

  In the above-described variable focus lens device, a liquid lens is used as a lens. However, as shown in FIG. 14A, the actuator of the present invention can be used even when a normal solid lens is used. it can. In this case, as shown in FIG. 14B, a voltage is applied to the two divided actuators 1 so that the two divided actuators 1 are displaced in the same direction, and the actuator 70 is moved in the axial direction (vertical direction in the drawing). ), And the position of the solid lens 140 is varied in accordance with the displacement, and the focus adjustment can be performed.

  14A is a schematic plan view showing the relationship between the solid lens and the actuator, and FIG. 14B is a cross-sectional view of FIG. 14A, in which the driving of the solid lens during voltage application is performed. FIG.

  In the above-described variable lens device, the actuator is used to adjust the lens focal position. For example, as shown in FIG. 16, the actuator 70 is applied to the optical pickup 120 as the variable lens device. The tilt angle α of the objective lens 122 can also be adjusted. Hereinafter, description will be made with reference to FIGS. 15 and 16.

  FIG. 15A is a schematic plan view showing the relationship between the objective lens and the actuator. FIG. 15B is a cross-sectional view of FIG. 15A and shows the driving of the objective lens when a voltage is applied. FIG. 16 is a schematic sectional view of the optical pickup.

  As shown in FIG. 16, the optical pickup 120 includes an objective lens 122 and an actuator 70, and irradiates the optical disc 121 with laser light condensed by the objective lens 122. As shown in FIG. 15B, a voltage is applied to the two divided actuators 1 so that the two divided actuators 1 are displaced in the opposite directions, and the actuator 70 is displaced. The tilt angle α can be adjusted by varying the tilt. Further, when an actuator is used for tilt angle adjustment in this way, it becomes easier to adjust to a desired tilt angle by using an actuator composed of three divided actuators.

  In the above-described embodiment, as the piezoelectric element, piezoelectric ceramics typified by PZT, organic materials having piezoelectricity such as PVDF (polyvinylidene fluoride), polymer materials such as conductive polymers and ion conduction actuators, and the like are used. be able to. In addition, the actuator has a structure in which piezoelectric elements are arranged on both surfaces of a metal plate, but a bimetal obtained by bonding two metal plates having different thermal expansion coefficients, a bimorph using a magnetostrictive element, or the like is used. Can do.

It is a schematic plan view of the actuator device in one embodiment of the present invention. It is a schematic sectional drawing in line AA 'of FIG. FIG. 2 is a schematic plan view of a divided actuator constituting the actuator device of FIG. 1. It is a figure explaining displacement amount U0 and generated force F0. It is an example of the simulation result which shows the displacement amount and generated force of the division | segmentation actuator which are shown in FIG. It is a schematic plan view of the division actuator as a comparative example. It is an example of the simulation result which shows the displacement amount and generated force of the division | segmentation actuator as a comparative example shown in FIG. FIG. 8 is a graph in which the displacement amount and generated force in the divided actuator of the present embodiment shown in FIG. 5 are plotted on the same graph, and the displacement amount and generated force in the divided actuator of the comparative example shown in FIG. FIG. 8 is a graph obtained by plotting and comparing the product of the displacement and generated force in the divided actuator of the present embodiment shown in FIG. 5 and the product of the displacement and generated force in the divided actuator of the comparative example shown in FIG. 7. It is the top view and sectional drawing for demonstrating the structure of the actuator of a strip type and a trapezoid type bimorph structure. It is sectional drawing which shows the operating characteristic at the time of the voltage application of a bimorph type actuator. It is a graph which shows the relationship between the displacement amount and generated force of an actuator of a strip type or a trapezoid type bimorph structure. It is a disassembled perspective view of the variable focus lens apparatus using the actuator of one Embodiment. It is a figure explaining the drive of the lens at the time of the voltage application in the variable focus lens apparatus which has a solid lens using the actuator of one Embodiment. It is a figure explaining the drive at the time of the voltage application of the objective lens in the optical pick-up using the actuator of one Embodiment. It is a schematic sectional drawing of the optical pick-up using the actuator of one Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Split actuator 2 Fixed end 6 Free end 7 Boundary line 10 Through-hole 20 Fixed member 40 Liquid lens part 50 Variable focus lens apparatus 70 Actuator apparatus 120 Optical pick-up 122 Objective lens 140 Solid lens P Piezoelectric element R1 Fixed area | region R2 Movable area (theta) A outer periphery Center angle of side free length θB ... Center angle of inner circumference free length

Claims (7)

An arc-shaped piezoelectric element having a first end that is a fixed end and a second end that is a free end;
A fixing member that fixes the first end so that θA <θB, where θA is the center angle of the outer peripheral free length of the piezoelectric element and θB is the center angle of the inner free length of the piezoelectric element And an actuator. The actuator according to claim 1,
The θB is 160 degrees or more and 190 degrees or less, and the θA is 110 degrees or more. The actuator according to claim 2, wherein
The θB is 170 degrees, and the θA is 120 degrees. Arc-shaped first and second piezoelectric elements each having a first end that is a fixed end and a second end that is a free end;
When the central angle of the outer peripheral free length of the first and second piezoelectric elements is θA, and the central angle of the inner peripheral free length of the first and second piezoelectric elements is θB, θA <θB is satisfied. An actuator device comprising: a first fixing member and a second fixing member for fixing the first end portions of the first and second piezoelectric elements, respectively. The actuator device according to claim 4,
The second end of the first piezoelectric element faces the first end of the second piezoelectric element;
The actuator device, wherein the second end of the second piezoelectric element is opposed to the first end of the first piezoelectric element. The actuator device according to claim 5,
An actuator device comprising an accommodating portion for accommodating a movable member between the first piezoelectric element and the second piezoelectric element. Arc-shaped first and second piezoelectric elements each having a first end that is a fixed end and a second end that is a free end;
When the central angle of the outer peripheral free length of the first and second piezoelectric elements is θA, and the central angle of the inner peripheral free length of the first and second piezoelectric elements is θB, θA <θB is satisfied. First and second fixing members for fixing the first ends of the first and second piezoelectric elements, respectively,
A lens that is supported by the second end of the first piezoelectric element and the second end of the second piezoelectric element, and is deformed or displaced by driving the first and second piezoelectric elements; A variable lens apparatus comprising:

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