JP2006261141A - Piezoelectric actuator and image input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric actuator which can be operated in a multidimensional direction and can obtain a large operation amount, and has a simple structure and low cost.
A piezoelectric actuator according to an embodiment includes piezoelectric ceramics A, B, and C that function as electrostrictive elements, electrodes A-1, A-2, and A-3 that drive the piezoelectric ceramic A, and piezoelectric ceramics. Electrodes B-1, B-2, B-3 for driving B, electrodes C-1, C-2, C-3 for driving piezoelectric ceramic C, and a connecting member D are provided. Each of the piezoelectric ceramics A, B, and C has a rectangular plate shape having a thickness, and is arranged radially so as to form an angle of 120 degrees. In addition, one side end surface of each piezoelectric ceramic is fixed to one of the sides of the triangular prism-shaped connecting member D.
[Selection] Figure 1

Description

  The present invention relates to a piezoelectric actuator and an image input device, and more particularly to a piezoelectric actuator suitable for use in a camera shake correction mechanism and an image input device including the piezoelectric actuator.

Conventionally, various types of piezoelectric actuators have been provided, and a camera shake correction mechanism using the piezoelectric actuators has been developed.
Furthermore, these piezoelectric actuators are used in image input devices.
For example, as a piezoelectric device for moving a movable body such as a piezoelectric device, particularly a positioning device such as a three-dimensional table or an ultrasonic motor, Japanese Patent Application Laid-Open No. 2000-22231 discloses three columnar shapes. The actuator of 3 is coupled in a triangular shape by three coupling members, and the actuator located on the base of the triangle is disposed on the support base and couples the two actuators located on the hypotenuse of the triangle A piezoelectric device is described in which a movable body is disposed on the movable body, and the movable body is variously displaced by applying a driving voltage to an arbitrary actuator.
Further, Patent Document 2 (Japanese Patent Laid-Open No. 9-267278) includes a triangular columnar metal columnar member and two piezoelectric elements bonded to each side surface, and controls the applied voltage. There is described a piezoelectric actuator that can be bent and torsionally deformed so that it can be finely moved and can also be coarsely moved by impact driving.
In FIGS. 12 and 13 of Patent Document 3 (Japanese Patent Laid-Open No. 7-184382), an X-shaped actuator is arranged so that a two-dimensional operation is possible with the intersection of the X characters as an operating point. An improved piezoelectric device is described.
Patent Document 4 (Japanese Patent Application Laid-Open No. 2004-77712) describes a camera shake correction device provided with two piezoelectric devices that are driven in the X direction and the Y direction.

"JP 2000-22231 A" "Japanese Patent Laid-Open No. 9-267278" "JP-A-7-184382" "Japanese Patent Laid-Open No. 2004-77712"

  However, in the conventional piezoelectric actuator described in the above background art, for example, in the case of the technique disclosed in Patent Document 1, since three columnar actuators are assembled in a triangular shape, However, there is a problem in that it cannot be driven in a direction perpendicular to this direction, and the joint portion connecting the two sides of the triangle becomes structurally unstable.

  In the case of the technique disclosed in Patent Document 2, the operation point that vibrates by receiving the vibration of the piezoelectric material in the three planes arranged in a delta shape (the drive point that is driven in contact with the driven object) is formed. It is costly, and it is necessary to increase the strength of the material for reliably transmitting the vibration of the piezoelectric material in the three planes to the operating point. Further, the vibration of the piezoelectric material in the three planes affects each other. There is a problem that the vibration of the synthesized operating point has mechanical stress and cannot drive.

  In the case of the technique disclosed in Patent Document 3, a piezoelectric element that expands and contracts is brought into contact with a driven object, and the driven object can be continuously moved in a predetermined direction. Although the drive amount can be larger than in the case of using it, only one-dimensional driving is possible, and when two-dimensional operation such as camera shake correction is required, two actuators are required, and the cost is doubled. In addition, since the two actuators interact with each other, accurate operation cannot be performed, and two operation points by the two actuators are located at an ideal position (for example, the rear surface of the CCD (Charge Coupled Device) of the image input device). In addition, there is a problem that it cannot be arranged on the optical axis).

Furthermore, Patent Document 3 discloses an actuator of a type in which an X-type piezoelectric plate is arranged and two-dimensional operation is possible at one operating point. However, in terms of cost, two actuators are used. In addition, there is a concern that the rigidity of the Y-direction operation actuator that is not operated during the X-direction operation affects the accuracy, and there are many problems in practical use.
Furthermore, in the case of the technique disclosed in Patent Document 4, as described above, a camera shake correction mechanism using a piezoelectric actuator is disclosed, but this is a driving method in which expansion and contraction of a piezoelectric element is used as it is for the operation of the shake correction mechanism. Therefore, there is a problem that the driving amount is insufficient.

The present invention has been made in view of the above-described circumstances, and a first object is to increase the number of electrostrictive elements despite the fact that the number of electrostrictive elements can be reduced as compared with the prior art, and thus the manufacturing cost can be kept lower than before. Another object of the present invention is to provide a piezoelectric actuator device capable of obtaining a driving amount and capable of two-dimensional driving.
In addition, a second object of the present invention is to enable a camera shake correction operation without causing mechanical stress in the vibration of the operating point for correction, and for two-dimensional driving for correction. An object of the present invention is to provide an image input apparatus capable of securing a sufficient amount.

In order to achieve the first object described above, a piezoelectric actuator device according to the present invention described in claim 1 includes one coupling member,
Three electrostrictive elements that are arranged radially with the coupling member as a central axis and whose side end surfaces are fixed to each other via the coupling member;
Electrode plates disposed on the front and back surfaces of the electrostrictive element;
It is characterized by comprising.

According to a second aspect of the present invention, there is provided the piezoelectric actuator device according to the present invention, wherein the three electrostrictive elements are arranged radially so as to have substantially equal angles.
According to a third aspect of the present invention, there is provided a piezoelectric actuator device according to the present invention, comprising: at least two electrode plates disposed on one surface of each of the electrostrictive elements; and the other surface of the electrostrictive element. And one electrode plate provided.
According to a fourth aspect of the present invention, there is provided a piezoelectric actuator device according to the present invention that is independent of each of a total of six electrode plates, two of which are arranged on one surface of each of the three electrostrictive elements. And a drive circuit for applying a voltage.
According to a fifth aspect of the present invention, there is provided a piezoelectric actuator device according to the present invention comprising a total of six electrode plates in which the drive circuit is disposed two on each side of each of the three electrostrictive elements. It is characterized in that different levels of voltages can be applied to each.

Furthermore, the piezoelectric actuator device according to the present invention described in claim 6 is provided with an operating projection for driving the driven body by contacting or fixing to the driven body to be driven at one end of the coupling member. It is characterized by being.
In order to achieve the above-described object, an image input device according to a seventh aspect of the present invention provides a photographing optical system that forms a subject image at a predetermined position, and converts the subject image into electronic data by a photoelectric conversion function. And an image pickup means and a piezoelectric actuator device according to any one of claims 1 to 6, wherein the image pickup means is driven in the direction perpendicular to the optical axis of the imaging optical system by driving the piezoelectric actuator device. The camera shake correction operation is performed by operating the switch.

The image input device according to the present invention described in claim 8 is characterized in that the piezoelectric actuator device directly drives a back surface portion of the imaging means.
Furthermore, the image input device according to the present invention described in claim 9 is the image input device according to claim 7 or 8, wherein the piezoelectric actuator device is on the optical axis or the optical axis. It is arranged in the vicinity of the top.

According to the present invention as set forth in claim 1, one coupling member;
Three electrostrictive elements that are arranged radially with the coupling member as a central axis and whose side end surfaces are fixed to each other via the coupling member;
Since the electrostrictive element is provided with electrode plates disposed on the front and back surfaces, the number of electrostrictive elements can be reduced as compared with the prior art, so that the manufacturing cost can be reduced and the two-dimensional operation can be suppressed. It is possible to provide a piezoelectric actuator device capable of satisfying the requirements.
Further, according to the invention described in claim 2, since the three electrostrictive elements are arranged radially so as to be substantially equiangular, the basic control of the operation in each of the two-dimensional directions is equivalent. Therefore, it is easy to control the piezoelectric to be applied to each electrode, and the circuit configuration for driving is simplified. Also in this aspect, a low-cost piezoelectric actuator device can be provided.

According to the invention of claim 3, at least two electrode plates disposed on one surface of each electrostrictive element and one sheet disposed on the other surface of the electrostrictive element. Since the structure including the electrode plate is provided, it is possible to provide a piezoelectric actuator device in which the number of electrostrictive elements can be suppressed to 3/4 of the conventional one, and thus the manufacturing cost can be suppressed to at most 3/4 of the conventional one.
According to the invention of claim 4, a voltage is independently applied to each of a total of six electrode plates arranged two on each side of each of the three electrostrictive elements. Since the driving circuit is provided, the manufacturing cost can be suppressed to at most 3/4 of the conventional one, the driving displacement can be ensured greatly, and the piezoelectric actuator device capable of two-dimensional operation is provided. be able to.

According to the invention described in claim 5, different levels of voltage are applied to each of a total of six electrode plates arranged two on each side of each of the three electrostrictive elements. Therefore, the number of piezoelectric ceramics can be reduced to 3/4 of the conventional one, and thus the manufacturing cost can be reduced to at most 3/4, and two-dimensional operation is possible. It is possible to provide a piezoelectric actuator device that can provide different operation amounts for each dimension.
Furthermore, according to the sixth aspect of the present invention, since one end of the coupling member is provided with the operation projection for driving or driving the driven body while being in contact with or fixed to the driven body to be driven, It is possible to provide a piezoelectric actuator device in which a dimensional motion can be realized at one operating point.

  According to the seventh aspect of the present invention, any one of the first to sixth aspects can be provided, such as a photographing optical system that forms a subject image at a predetermined position, an imaging unit that converts the subject image into electronic data by photoelectric conversion, and Since the image pickup means is configured to move in a direction perpendicular to the optical axis of the photographic optical system by driving the piezoelectric actuator device, the image pickup means is highly accurate. An image input apparatus that can be driven two-dimensionally and has a highly reliable camera shake correction function can be provided.

According to the eighth aspect of the present invention, since the piezoelectric actuator device is configured to drive the back surface portion of the image pickup means, the action point for moving the image pickup means can be set to an ideal position. In addition, the presence of the piezoelectric actuator device does not interfere with the optical system, and an image input device having a more reliable camera shake correction function can be provided.
Furthermore, according to the ninth aspect of the invention, since the piezoelectric actuator device can be disposed on the optical axis or in the vicinity of the optical axis, the driving amount in the optical axis direction that is a dimension that particularly requires correction. It is possible to provide an image input device capable of accurately controlling the image.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a piezoelectric actuator and an image input device according to the present invention will be described in detail in the order of [First Embodiment] and [Second Embodiment] with reference to the drawings.
[First Embodiment]
FIG. 1 is a configuration diagram showing a basic configuration of a piezoelectric actuator according to a first embodiment of the present invention.
In the figure, the piezoelectric actuator of the present embodiment includes piezoelectric ceramics A, B, and C that function as electrostrictive elements, and electrodes A-1, A-2, and A-3 (rear surface side) that drive the piezoelectric ceramic A. And electrodes B-1, B-2, B-3 (rear surface side) for driving the piezoelectric ceramic B, electrodes C-1, C-2, C-3 (rear surface side) for driving the piezoelectric ceramic C, And a connecting member D.

Each of the piezoelectric ceramics A, B, and C has a shape of a rectangular plate (plane) having a thickness, and is arranged radially (star shape) so as to form an angle of 120 degrees around the virtual central axis. Has been. Further, in this arrangement, one side end face of each ceramic is fixed to either side of the connecting member D as a triangular prism-shaped connecting member.
Each of the piezoelectric ceramics A, B, and C has electrodes A-1, A-2, A-3 (or electrodes B-1, B-2, B-3) or (having at least one polarity on the front and back) or ( Electrodes C-1, C-2, C-3) are arranged.

FIG. 2 is a configuration diagram showing a configuration when the piezoelectric actuator according to the first embodiment of the present invention is used as a driving body.
As shown in the figure, when the piezoelectric actuator of the present embodiment is used as a driving body, an operating projection E that operates as an operating point is fixed to one end of a triangular prism-shaped connecting member D.
The connecting member D is joined (connected) or fixed to an external driven body.

Hereinafter, the operation of the piezoelectric actuator of the present embodiment will be described.
As described above, each of the piezoelectric ceramics A, B, C has electrodes A-1, A-2, A-3 (or electrodes B-1, B-2, B-) having at least one of positive and negative polarities on the front and back sides. 3) or (electrodes C-1, C-2, C-3) is arranged, and a positive voltage is applied to one of these electrodes and a negative voltage is applied to the other, for example. Then, the piezoelectric ceramic is stretched, and conversely, the piezoelectric ceramic is contracted when a voltage having the opposite polarity is applied between the electrodes.

  In FIG. 1, the expansion / contraction direction of the piezoelectric ceramic A by the electrodes A-1, A-2, A-3 is indicated by a double-ended arrow A, and the expansion / contraction direction of the piezoelectric ceramic B by the electrodes B-1, B-2, B-3 is shown. A double-ended arrow B indicates the expansion / contraction direction of the piezoelectric ceramic C by the electrodes C-1, C-2, and C-3.

As described above, in the present invention, the three piezoelectric ceramic plates are arranged radially (star shape), and each of the three piezoelectric ceramic plates includes two or more electrodes. Compared with the X-type piezoelectric ceramic plate disclosed in No. 3, the number of piezoelectric ceramic plates is 3/4, and the manufacturing cost can be suppressed to 3/4 at most.
In addition, since the piezoelectric ceramics A, B, and C are arranged at equal angles (120 degrees), the basic operations in the A direction, the B direction, and the C direction can be controlled equally. Control of the voltage to be applied to is easy.
Furthermore, if a voltage application that combines the operations in the A direction, the B direction, and the C direction is applied to each electrode, it can be operated in any two-dimensional direction.

Further, as shown in FIG. 2, since one operation point (operation protrusion E) is provided at one end of a triangular prism-shaped connecting member D for fixing (bonding) the piezoelectric ceramics A, B, and C, the two-dimensional structure described above is used. Operation can be realized at this one operating point (operating protrusion E).
Note that the piezoelectric actuator according to the present embodiment may be configured to include a drive circuit (not shown) for driving the piezoelectric actuator. In this case, the drive circuit is independently applied with voltage to each of at least two (total of at least six) electrode plates disposed on one surface of each of the three electrostrictive elements. It is possible to make such a circuit configuration, or to apply a voltage of a different level.
Next, an example in which the piezoelectric actuator according to the present embodiment is used in a camera shake correction mechanism will be described.
The camera shake correction mechanism has a function of detecting the movement of the camera with a shake sensor and shifting or tilting the CCD or the optical system with respect to the optical axis so as to cancel the shake. It can be arranged on various lenses, and is a well-known technique as shown in Patent Document 4.

  In a shake correction mechanism of the type that moves the CCD horizontally, the required actuator is a highly accurate and highly responsive two-dimensional actuator, but conventionally there is no corresponding inexpensive two-dimensional actuator, so there is no X direction. The Y direction is driven by separate actuators. Therefore, the problem of the operating point for the CCD arises. In other words, unless the CCD is moved by applying a force to a well-balanced point in the vertical and horizontal directions, the CCD tends to tilt during horizontal shift (for example, if the right end is moved upward, the left end will follow the friction and weight balance). However, in the past, although it was difficult to move the CCD with high accuracy, it was necessary to use two actuators. The action point had to be placed at a position deviating from the above.

On the other hand, when the piezoelectric actuator according to the present embodiment is used, a correction mechanism can be realized in which the action point (operation point) of the two-dimensional actuator is only one point (operation protrusion E). It is possible to set the action point at an ideal position of the image input apparatus, and it is possible to obtain a more reliable camera shake correction mechanism.
In the actuator shown in Patent Document 3, it is possible to set the action point (operation point) to one point, but in the case of the piezoelectric actuator according to the present embodiment, the conventional 3/4 piezoelectric ceramics. By using the number of sheets, it is possible to configure a driving body whose cost is at most 3/4.

  Further, since the CCD can be moved up and down and left and right with only one point (the operating projection E), a complicated mechanism for configuring the action point is not required, and the CCD can be operated in a two-dimensional direction. It is also possible to transmit the driving force directly to the backside of the CCD held in a state, and it is possible to suppress excessive mechanism deflection and to minimize operation loss due to fixed play. At the same time, the mechanism is simpler than the conventional one, thereby realizing an inexpensive and highly reliable device.

Note that the piezoelectric actuator according to the present embodiment is not limited to the camera shake correction mechanism, and can also be used for pixel-shifted shooting.
As described above, the piezoelectric actuator of the present invention is not limited to this embodiment, and various configurations are possible without departing from the gist of the present invention.
[Second Embodiment]

FIG. 3 is a block diagram showing the configuration of the main part of the CCD drive unit of the image input apparatus according to the second embodiment of the present invention.
In the figure, a CCD drive unit 10 that is characteristic of the image input apparatus of the present embodiment includes a photographing optical system 1 that obtains an optical image of a subject by a lens and the like, and an optical image of the subject formed at a predetermined position. The CCD 2 for converting the signal, the optical axis 3 optically connecting the photographing optical system 1 and the CCD 2, the piezoelectric actuator 4 in which the back surface of the CCD 2 and the operating protrusion are bonded or fixed, the operating protrusion of the piezoelectric actuator 4 and the CCD 2 And a drive point 5 formed as a contact point with the back surface.

In addition, about the other component of the image input device of this Embodiment, the same thing as a well-known image input device as shown in patent document 4 can be used (it is not the characteristic component of this invention). Therefore, illustration and description are omitted).
The operation of the CCD drive unit according to this embodiment will be described below.
In one embodiment of this CCD drive mechanism, the voltage value of the voltage output from the shake detection device (not shown) corresponds to the shake amount of this device, and the voltage indicating this voltage value is a piezoelectric value. Input to the actuator 4. As a result, the piezoelectric actuator 4 takes a reverse displacement operation corresponding to the shake amount, and this reverse displacement operation is transmitted to the CCD 2 bonded or fixed to the piezoelectric actuator 4. The blur amount is corrected.

The amount of blur can be corrected by moving the CCD 2 along a plane orthogonal to the optical axis 3. However, the present invention is not necessarily limited to moving the CCD 2 along the optical axis 3, and can be moved close to the optical axis 3, and is not limited to the direction of the optical axis 3. It is also possible to perform correct correction.
In another embodiment of the CCD drive mechanism, in order to enable a predictive operation, the voltage value of the voltage input to the piezoelectric actuator 4 is set to a voltage corresponding to the amount of blurring during past shooting. It is also possible to use a voltage value stored as a value.
The shake detection device can employ shake detection means using a gyro sensor or the like.
As described above, the image input device of the present invention is not limited to the present embodiment, and various configurations can be made within the scope of the claims.

It is a block diagram which shows the basic composition of the piezoelectric actuator which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the structure in the case of using the piezoelectric actuator which concerns on the 1st Embodiment of this invention as a drive body. It is a block diagram which shows the structure of the principal part of the CCD drive unit of the image input device which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

1 Shooting optical system 2 CCD
3 Optical axis 4 Piezoelectric actuator 5 Drive point A, B, C Piezoelectric ceramics D Connecting member E Actuation protrusion (operation point)
A-1 to A-2 Electrode (Piezoelectric Ceramics A side)
B-1 to B-2 electrodes (piezoelectric ceramics B side)
C-1 to C-2 electrodes (piezoelectric ceramics C side)

Claims (9)

One coupling member;
Three electrostrictive elements that are arranged radially with the coupling member as a central axis and whose side end surfaces are fixed to each other via the coupling member;
Electrode plates disposed on the front and back surfaces of the electrostrictive element;
A piezoelectric actuator device comprising: 2. The piezoelectric actuator device according to claim 1, wherein the three electrostrictive elements are arranged radially so as to have substantially equal angles. And at least two electrode plates disposed on one surface of each of the electrostrictive elements, and one electrode plate disposed on the other surface of the electrostrictive elements. The piezoelectric actuator device according to claim 1 or 2. 2. A driving circuit for independently applying a voltage to each of a total of six electrode plates disposed two on one surface of each of the three electrostrictive elements. 3. The piezoelectric actuator device according to 3. The drive circuit is capable of simultaneously applying different levels of voltage to each of a total of six electrode plates arranged two on each side of each of the three electrostrictive elements. The piezoelectric actuator device according to claim 4. 6. An operating projection for driving the driven body by being brought into contact with or fixed to the driven body to be driven is provided at one end of the coupling member. The piezoelectric actuator device described in 1. A photographing optical system for forming a subject image at a predetermined position;
Imaging means for converting the subject image into electronic data by photoelectric conversion;
A piezoelectric actuator device according to any one of claims 1 to 6,
An image input device that performs a camera shake correction operation by operating the imaging unit in a direction perpendicular to the optical axis of the imaging optical system by driving the piezoelectric actuator device. The image input device according to claim 7, wherein the piezoelectric actuator device directly drives a back surface portion of the imaging unit. 9. The image input device according to claim 7, wherein the piezoelectric actuator device is disposed on the optical axis or in the vicinity of the optical axis.

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