JP2008029063A - Piezoelectric actuator, and transfer device and camera shake correction device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric actuator driving an object to be driven efficiently and smoothly while achieving the miniaturization of a device. <P>SOLUTION: The piezoelectric actuator 1 is provided with a metal plate 2 of a square shape having flexibility. On the top surface 2a side of this metal plate 2, a plurality of quadrangular prism-shaped protruding portions 3 is provided. On the bottom surface 2b side of the metal plate 2, a first piezoelectric element A arranged at one side of its center part and a second piezoelectric element B arranged at the other side are provided on a straight line. Furthermore, on the bottom surface 2b side of the metal plate 2, a third piezoelectric element C arranged at one side in the direction orthogonal to the first and second piezoelectric elements A, B at the center part and a fourth piezoelectric element D arranged at the other side are provided on a straight line. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a piezoelectric actuator, a conveyance device using the piezoelectric actuator, and a camera shake correction device.

Conventionally, piezoelectric actuators configured using piezoelectric elements have been proposed. This piezoelectric actuator is attached to a columnar elastic body, a single protrusion protruding from the center of the elastic body, and both sides of the protrusion on the front and back surfaces of the elastic body. Each is composed of a pair of piezoelectric elements. When a voltage is applied to each piezoelectric element, the piezoelectric element expands or contracts, and the elastic body is deformed accordingly. Due to the deformation of the elastic body, the single protrusion is displaced in the vertical direction and in the horizontal direction intersecting with this, and the displacement of the single protrusion drives the drive target in the vertical direction and the horizontal direction. (For example, refer to Patent Document 1).
JP 7-274556 A

  However, in the conventional piezoelectric actuator described above, a single protrusion is provided, and the single object is displaced to drive the drive target. Therefore, since the drive target is unstable only by being supported by a single protrusion, a separate support member for stably supporting the drive target is required, and the apparatus becomes large. In addition, since driving is performed by a single protrusion, driving becomes inefficient and the target to be driven cannot be driven smoothly.

  The present invention has been made in view of such conventional problems, and a piezoelectric actuator capable of efficiently and smoothly driving an object to be driven while reducing the size of the apparatus, a conveying apparatus using the same, and camera shake correction. An object is to provide an apparatus.

  In order to solve the above-mentioned problem, in the piezoelectric actuator according to the first aspect of the present invention, a flexible plate-like member, a plurality of protrusions provided on one surface of the plate-like member, and the plate-like member are provided. A plurality of piezoelectric elements provided on at least one of the one surface and the other surface of the member, and by applying a driving voltage to the plurality of piezoelectric elements, the plate-shaped member is bent and deformed, and the plurality of the plurality of piezoelectric elements are provided. A feature is that the projection is displaced.

  In the piezoelectric actuator according to a second aspect of the present invention, the plurality of protrusions are provided over substantially the entire surface of the one surface excluding the peripheral portion.

  The piezoelectric actuator according to a third aspect of the invention is characterized in that the plurality of protrusions are provided at equal intervals.

  In the piezoelectric actuator according to a fourth aspect of the present invention, the plurality of piezoelectric elements includes first and second piezoelectric elements arranged linearly at a central portion of the plate-like member, and these It consists of the 3rd and 4th piezoelectric element arrange | positioned in the direction orthogonal to the arrangement direction of the 1st and 2nd piezoelectric element.

  In the piezoelectric actuator according to the invention described in claim 5, the plate member is a metal plate.

  According to a sixth aspect of the present invention, the piezoelectric actuator is characterized in that the plurality of protrusions are integrally formed on the metal plate.

  The piezoelectric actuator according to claim 7 further includes control means for controlling a drive voltage applied to the plurality of piezoelectric elements, and the control means moves the plate-like member to the plurality of protrusions. The driving voltage is controlled so that the deformation operation time when bending and deforming in the protruding direction of the part is longer than the deformation operation time when bending and deforming in the non-projecting direction opposite to the protruding direction. And

  In addition, the transport device according to the invention of claim 8 includes the piezoelectric actuator according to any one of claims 1 to 7 and a transport member that is transported in accordance with the displacement of the plurality of protrusions. It is characterized by.

  According to a ninth aspect of the present invention, there is provided a camera shake correction apparatus comprising the piezoelectric actuator according to any one of the first to seventh aspects, and an image sensor that is driven in accordance with the displacement of the protrusion. Features.

  According to the piezoelectric actuator according to the present invention, since the drive target can be supported by the plurality of protrusions, it is not necessary to separately provide a support member for supporting the drive target, thereby reducing the size of the apparatus. Can do. In addition, since the driving target can be continuously driven by the plurality of protrusions, efficient and smooth driving is possible.

  Further, according to the transport apparatus according to the present invention, since the transport target can be supported by the plurality of protrusions, it is not necessary to provide a support member for supporting the transport target separately, thereby reducing the size of the apparatus. Can be planned. Moreover, since a conveyance object can be continuously conveyed by a plurality of protrusions, efficient and smooth conveyance is possible.

  Further, according to the camera shake correction device according to the present invention, since the imaging element can be supported by the plurality of protrusions, it is not necessary to separately provide a support member for supporting the imaging element, thereby reducing the size of the apparatus. Can be achieved. In addition, since the imaging element can be continuously driven by the plurality of protrusions, efficient and smooth driving is possible.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
(First embodiment)

  FIG. 1A is a plan view of the piezoelectric actuator 1 according to the first embodiment of the present invention, and FIG. 1B is a front view thereof. The piezoelectric actuator 1 includes a metal plate 2 that is square and has flexibility. On the upper surface 2 a side of the metal plate 2, a plurality of quadrangular columnar projections 3 are provided over the front surface excluding the peripheral portion 6. As shown in FIG. 2B, the protrusions 3 are formed by engraving the metal plate 2 with longitudinal grooves 4 and transverse grooves 5 that are equally spaced. It is provided at equal intervals.

  On the lower surface 2b side of the metal plate 2, a first piezoelectric element A disposed on one side of the central portion and a second piezoelectric element B disposed on the other side are provided on a straight line. Further, on the lower surface 2b side of the metal plate 2, a third piezoelectric element C disposed on one side in a direction orthogonal to the first and second piezoelectric elements A and B is disposed on the other side of the central portion. The fourth piezoelectric element D is provided on a straight line. These first to fourth piezoelectric elements A to D have a gap between opposing end portions and have a length that reaches the end portions of the projections 3 located at both end portions, and the lower surface 2b is formed by a conductive adhesive. It is affixed to. Wiring is connected to the surface of each of the piezoelectric elements A to D so that electric charges can be applied, and the metal plate 2 is connected to ground. Further, the metal plate 2 is fixed at the four peripheral edges by the fixing member 7. The first to fourth piezoelectric elements A to D have a characteristic that contracts when a positive charge is applied and expands when a negative charge is applied.

  FIG. 2 is a block diagram showing a circuit configuration of the present embodiment. The memory 8 stores programs and the like. The CPU 9 executes processing according to the program stored in the memory 8 to control the transistors 10a to 10d and to control the voltages applied to the first to fourth piezoelectric elements A to D via the FETs 11a to 11d. . In addition to the program, the memory 8 stores a first second piezoelectric element control table 8a shown in FIG. 3A and a third fourth piezoelectric element control table 8b shown in FIG. Each table 8a, 8b stores, for example, positive / negative of the voltage applied to each piezoelectric element A-D corresponding to the patterns (1)-(4), (11)-(14).

  In the following description, as shown in FIG. 1, the first piezoelectric element A side is “left”, the second piezoelectric element B side is “right”, the third piezoelectric element C side is “front”, the first The 4th piezoelectric element D side is referred to as “rear”.

  In the present embodiment having the above configuration, as shown in FIG. 4 (0), a pedestal 13 is disposed on the protrusion 3 of the piezoelectric actuator 1 and is urged by an urging means (not shown). It is pressed against the protrusion 3. A CCD 12 as a conveyance target connected to the wiring 14 is fixed at the center of the pedestal 13. In FIG. 4, the third and fourth piezoelectric elements C and D are omitted, and only the first and second piezoelectric elements A and B are shown. In FIG. 6, the first and second piezoelectric elements are reversed. The elements A and B are omitted, and only the third and fourth piezoelectric elements C and D are shown. Further, the protrusion 3 is 3a to 3f in order from the left in FIG. 4, and 3g to 3l in order from the front in FIG.

  If the applied voltages to the first and second piezoelectric elements A and B are both “0”, the first and second piezoelectric elements A and B maintain a straight shape as shown in FIG. To do. Therefore, the metal plate 2 also maintains a straight shape, and the projecting portions 3 a to 3 f are in contact with the lower surface of the base 13 and are stationary.

  Subsequently, when the applied voltages to the first and second piezoelectric elements A and B are both set to “−” corresponding to the pattern (1) shown in FIG. 5, as shown in FIG. The second piezoelectric elements A and B extend together. Therefore, the metal plate 2 bulges downward. Therefore, on the first piezoelectric element A side, the protrusion 3a is displaced upward while rotating in the right direction, and the protrusions 3b and 3c are displaced downward while rotating in the right direction. On the second piezoelectric element A side, the protrusions 3d and 3e are displaced downward while rotating leftward, and the protrusion 3f is displaced upward while rotating leftward.

  Subsequently, when the voltage applied to the first piezoelectric element A is set to “+” and the voltage applied to the second piezoelectric element B is set to “−” corresponding to the pattern (2) shown in FIG. ), The first piezoelectric element A contracts and the second piezoelectric element B expands. Therefore, the first piezoelectric element A side of the metal plate 2 bulges upward, the second piezoelectric element B side bulges downward, and the metal plate 2 is deformed into a waveform. Therefore, on the first piezoelectric element A side, the protrusion 3a is displaced downward while rotating leftward, and the protrusions 3b and 3c are displaced upward while rotating leftward. On the second piezoelectric element B side, the protrusions 3d and 3e are displaced upward while rotating in the right direction, and the protrusion 3f maintains a state substantially similar to (1).

  Subsequently, when the voltage applied to the first and second piezoelectric elements A and B is both set to “+” corresponding to the pattern (3) shown in FIG. The second piezoelectric elements A and B extend together. Therefore, the metal plate 2 bulges upward. Therefore, on the first piezoelectric element A side, the protrusions 3a and 3b are displaced downward while rotating leftward, and the protrusion 3c is displaced upward while rotating leftward. On the second piezoelectric element B side, the protrusions 3d and 3e are displaced upward while rotating in the left direction, and the protrusion 3f is displaced downward in the right direction.

  Subsequently, when the voltage applied to the first piezoelectric element A is set to “−” and the voltage applied to the second piezoelectric element B is set to “+” corresponding to the pattern (4) shown in FIG. ), The first piezoelectric element A expands and the second piezoelectric element B contracts. Therefore, the first piezoelectric element A side of the metal plate 2 bulges downward, the second piezoelectric element B side bulges upward, and the metal plate 2 is deformed into a waveform. Therefore, on the first piezoelectric element A side, the protrusion 3a is displaced upward while rotating rightward, 3b is displaced downward while rotating rightward, and the protrusion 3c is rotated leftward. While moving downward. On the second piezoelectric element B side, the protrusion 3d is displaced upward while rotating leftward, the protrusion 3e is displaced upward while rotating leftward, and the protrusion 3f is (3) And maintain almost the same state.

  Therefore, as shown in FIG. 5, the first and second piezoelectric elements A and B are cycled in the cycle of (1) → (2) → (3) → (4) → (1) →. By applying a voltage, each protrusion 3 can be elliptically moved counterclockwise within the vertical plane, and as a result, the CCD 12 can be conveyed integrally with the pedestal 13 in the left direction. On the contrary, by applying a voltage to the first and second piezoelectric elements A and B in a cycle of (4) → (3) → (2) → (1) → (4). The protrusions 3 can be elliptically moved clockwise in the vertical plane, and as a result, the CCD 12 can be conveyed integrally with the pedestal 13 in the right direction.

  On the other hand, if the voltage applied to the third and fourth piezoelectric elements C and D is both “0”, the third and fourth piezoelectric elements C and D maintain a straight shape as shown in FIG. To do. Therefore, the metal plate 2 also maintains a straight shape, and the protrusions 3g to 3l are in contact with the lower surface of the base 13 and are stationary.

  Subsequently, in response to the pattern (11) shown in FIG. 7, when the applied voltages to the third and fourth piezoelectric elements C and D are both set to “−”, the third and fourth piezoelectric elements C and D, as shown in FIG. The fourth piezoelectric elements C and D extend together. Therefore, the metal plate 2 bulges downward. Therefore, on the third piezoelectric element C side, the protrusion 3g is displaced upward while rotating backward, and the protrusions 3h and 3i are displaced downward while rotating backward. On the fourth piezoelectric element D side, the protrusions 3j and 3k are displaced downward while rotating forward, and the protrusion 3l is displaced upward while rotating forward.

  Subsequently, when the voltage applied to the third piezoelectric element C is set to “+” and the voltage applied to the second piezoelectric element B is set to “−” corresponding to the pattern (12) shown in FIG. ), The third piezoelectric element C contracts and the fourth piezoelectric element D expands. Accordingly, the third piezoelectric element C side of the metal plate 2 bulges upward, the fourth piezoelectric element D side bulges downward, and the metal plate 2 is deformed into a waveform. Therefore, on the third piezoelectric element C side, the protrusion 3g is displaced downward while rotating forward, and the protrusions 3h and 3i are displaced upward while rotating forward. On the fourth piezoelectric element D side, the projecting portions 3j and 3k are displaced upward while rotating backward, and the projecting portion 31 is maintained in a state substantially similar to (11).

  Subsequently, when the applied voltages to the third and fourth piezoelectric elements C and D are both set to “+” corresponding to the pattern (13) shown in FIG. The fourth piezoelectric elements C and D extend together. Therefore, the metal plate 2 bulges upward. Therefore, on the third piezoelectric element C side, the protrusions 3g and 3h are displaced downward while rotating forward, and the protrusion 3i is displaced upward while rotating forward. On the fourth piezoelectric element D side, the protrusions 3j and 3k are displaced upward while rotating forward, and the protrusion 31 is displaced downward in the rear direction.

  Subsequently, when the voltage applied to the third piezoelectric element C is set to “−” and the voltage applied to the fourth piezoelectric element D is set to “+” corresponding to the pattern (14) shown in FIG. ), The third piezoelectric element C expands and the fourth piezoelectric element D contracts. Accordingly, the third piezoelectric element C side of the metal plate 2 bulges downward, the fourth piezoelectric element D side bulges upward, and the metal plate 2 is deformed into a waveform. Therefore, on the third piezoelectric element C side, the protrusion 3g is displaced upward while rotating backward, 3h is displaced downward while rotating backward, and the protrusion 3i is rotated forward. While moving downward. On the fourth piezoelectric element D side, the protrusion 3j is displaced upward while rotating forward, the protrusion 3k is displaced upward while rotating forward, and the protrusion 3l is (13) And maintain almost the same state.

  Therefore, as shown in FIG. 7, the third and fourth piezoelectric elements C and D are cycled in the above cycle (11) → (12) → (13) → (14) → (11) →. By applying a voltage, each projection 3 can be elliptically moved forward in the vertical plane, and as a result, the CCD 12 can be transported integrally with the base 13 in the forward direction. On the contrary, by applying a voltage to the third and fourth piezoelectric elements C and D in a cycle of (14) → (13) → (12) → (11) → (14). Each projection 3 can be elliptically moved backward in the vertical plane, and as a result, the CCD 12 can be transported integrally with the base 13 in the rearward direction.

That is, according to the piezoelectric actuator 1 according to the present embodiment, when the applied voltage at the time of contraction is 30 V and the applied voltage at the time of expansion is −30 V, as shown in FIGS. .338 (μm), vertical displacement 1.250 (μm), displacement ratio (horizontal direction) 1.64, displacement ratio (vertical direction) 3.60, and these vertical and horizontal displacements can be obtained. In addition, it is possible to carry in the respective directions shown in the following (A) to (D).
(A) Transport in the left direction: (1) → (2) → (3) → (4) → (1).
(B) Transport in the right direction: (4) → (3) → (2) → (1) → (4).
(C) Forward transport: (11) → (12) → (13) → (14) → (11).
(D) Transport in the backward direction: (14) → (13) → (12) → (11) → (14).

  Therefore, the CCD 12 can be driven from the center to all directions on the plane by controlling the applied voltage and combining the conveyances (a) to (d) in each direction. Therefore, a camera shake correction mechanism in a digital camera can be achieved by applying a voltage to the piezoelectric elements A to D of the piezoelectric actuator 1 and driving the CCD 12 according to the detected camera shake amount and camera shake direction.

(Second Embodiment)
FIG. 10 is a diagram showing a first second piezoelectric element control table 8a and a third fourth piezoelectric element control table 8b stored in the memory 8 in the second embodiment of the present invention. In the present embodiment, the respective tables 8a and 8b store the positive and negative voltages applied to the piezoelectric elements A to D corresponding to the patterns (1) to (4) and (11) to (14), respectively. In addition, the energization time is stored. This energization time is set to 2t, which is twice that of patterns (1), (2), (11), and (12), while patterns (3), (4), (13), and (14) are t. ing.

  Therefore, when the CPU 9 controls the voltage applied to the first and second piezoelectric elements A and B according to the information stored in the first second piezoelectric element control table 8a, as shown in FIG. Switching from 2) and (2) to (3) is performed at the timing of time 2t, and switching from (3) to (4) and from (4) to (1) is performed at the timing of time t. It becomes. Therefore, in FIG. 4, the time required to change from (1) to (2) and (2) to (3) is changed to the time required to change from (3) to (4) and from (4) to (1). Can be longer. Therefore, it is possible to reduce an impact when the protrusion 3 is displaced upward and comes into contact with the pedestal 13, and it is possible to prevent the inconvenience of the pedestal 13 jumping up due to the impact.

  When the CPU 9 controls the applied voltages of the first and second piezoelectric elements A and B according to the information stored in the third and fourth piezoelectric element control table 8b, as shown in FIG. The switching from 12) and (12) to (13) is performed at the timing of time 2t, and the switching from (3) to (4) and (4) to (1) is performed at the timing of time t. It becomes. Therefore, in FIG. 6, the time required to transform from (11) to (12) and (12) to (13) is the time required to transform from (13) to (14) and from (14) to (11). Can be longer. Therefore, it is possible to reduce an impact when the protrusion 3 is displaced upward and comes into contact with the pedestal 13, and it is possible to prevent the inconvenience of the pedestal 13 jumping up due to the impact.

  That is, in order to increase the conveyance speed of the CCD 12 integrated with the base 13 on the protrusion 3, it is necessary to shorten the energization cycle. However, if the energization cycle is shortened, the pedestal 13 may jump up due to an impact when the protrusion 3 is displaced upward and comes into contact with the pedestal 13, and it may be difficult to drive the pedestal 13 properly. However, in this embodiment, since the energization timing of (1) → (2) → (3) and (11) → (12) → (13) is made longer than the other energization timings, the protrusion 3 Can be mitigated when it is displaced upward and comes into contact with the pedestal 13. Therefore, even if the conveyance speed is increased, it can be conveyed properly.

  In the present embodiment, the piezoelectric elements A to D are provided on the lower surface 2b side of the metal plate 2, but may be provided on the upper surface 2a side, and the upper surface 2a side and the lower surface 2b side. It may be provided on both sides. Further, the protrusion 3 is formed integrally with the metal plate 2, but both may be formed separately and the protrusion 3 may be bonded to the metal plate 2. Furthermore, the piezoelectric actuator according to the present invention can be used not only for driving the image pickup device (CCD) in the digital camera described above but also for conveying and driving various objects.

(A) is a top view of the piezoelectric actuator which concerns on the 1st Embodiment of this invention, (b) is a front view. It is a block diagram which shows the circuit structure of the embodiment. (A) is a figure which shows the 1st 2nd piezoelectric element control table, (b) is a figure which shows each 3rd, 4th piezoelectric element control table. (0)-(4) are operation | movement transition diagrams in 1st Embodiment. It is a voltage application transition diagram of the same embodiment. (0)-(4) are operation | movement transition diagrams in 1st Embodiment. It is a voltage application transition diagram of the same embodiment. It is a figure which shows the locus | trajectory of CCD center point. It is a figure which shows the amount of displacement. (A) is a figure which shows each 1st, 2nd piezoelectric element control table in the 2nd Embodiment of this invention, (b) is a figure which shows each 3rd, 4th piezoelectric element control table. It is a voltage application transition diagram of the same embodiment. It is a voltage application transition diagram of the same embodiment.

Explanation of symbols

A to D Piezoelectric element 2a Upper surface 2b Lower surface 3 Protruding portion 4 Vertical groove 5 Horizontal groove 8 Memory 8a First second piezoelectric element control table 8b Third fourth piezoelectric element control table 9 CPU
12 CCD

Claims (9)

A plate-like member having flexibility;
A plurality of protrusions provided on one surface of the plate member;
A plurality of piezoelectric elements provided on at least one surface of the plate-like member and the other surface;
A piezoelectric actuator configured to apply a driving voltage to the plurality of piezoelectric elements to bend and deform the plate-like member to displace the plurality of protrusions.   The piezoelectric actuator according to claim 1, wherein the plurality of protrusions are provided over substantially the entire surface of the one surface excluding the peripheral portion.   The piezoelectric actuator according to claim 1, wherein the plurality of protrusions are provided at equal intervals.   The plurality of piezoelectric elements are arranged in a central portion of the plate-like member in a direction orthogonal to the first and second piezoelectric elements arranged linearly and the arrangement direction of the first and second piezoelectric elements. The piezoelectric actuator according to claim 1, 2, or 3, comprising the third and fourth piezoelectric elements.   The piezoelectric actuator according to claim 1, wherein the plate member is a metal plate.   6. The piezoelectric actuator according to claim 5, wherein the plurality of protrusions are integrally formed on the metal plate.   The control unit further controls an energization cycle when a driving voltage is applied to the plurality of piezoelectric elements, and the control unit energizes the plate-like member in a bending direction in the protruding direction of the plurality of protrusions. 7. The piezoelectric actuator according to claim 1, wherein the energization cycle is controlled so as to be longer than an energization time when the electrode is bent and deformed in a non-projecting direction opposite to the projecting direction. .   A conveying apparatus comprising the piezoelectric actuator according to claim 1, further comprising a conveying member that is conveyed along with the displacement of the plurality of protrusions. 8. A camera shake correction apparatus comprising: the piezoelectric actuator according to claim 1; and an image sensor that is driven in accordance with displacement of the protrusion.

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