JP2010233404A - Bending displacement element, driving device having the bending displacement element, and use of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bending displacement element which combines a high drive speed and a mechanical strength. <P>SOLUTION: The bending displacement element 7 is induced to cause a bending displacement when applied with voltage. The bending displacement element 7 includes a piezoelectric element 5 formed by laminating piezoelectric materials 5a via electrodes thinner than the piezoelectric materials 5a, a frictional member 3, and an intermediate member 4. The intermediate member 4 is composed of a fixed area 4a fixed to a free end not containing a fixed end of the piezoelectric element 5, and a functional area 4b provided with the frictional member 3. The intermediate member 4 is not electrically connected to the piezoelectric materials 5a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a bending displacement element, a driving device including the bending displacement element, and use thereof.

  Conventionally, a driving device for driving a driven body using an electromechanical conversion element (piezoelectric element) has been proposed. Such a driving device is used for driving a lens in an optical device such as a photographing lens of a camera, for example.

  For example, in Patent Document 1 and Patent Document 2, a piezoelectric element that bends when a voltage is applied, a holding member that holds one end of the piezoelectric element, a driven body that is in frictional contact with the free end of the piezoelectric element, and the piezoelectric element and the driven An invention relating to a driving device that includes a pressurizing mechanism for pressing a body with a constant force and moves a driven body that is in frictional contact with a bending displacement of a piezoelectric element is disclosed.

  The piezoelectric element has a structure in which piezoelectric bodies such as piezoelectric ceramics are attached to both main surfaces of a metal reinforcing plate (hereinafter referred to as “shim material”). The piezoelectric element is bent and displaced by changing the contraction direction of the piezoelectric body attached to each main surface. Further, in such a driving device, a stable operation of the driven body can be realized by adhering and fixing a friction member to the tip of the piezoelectric element and bringing the friction member and the driven body into frictional contact.

JP 2007-252103 A (published September 27, 2007) JP 2007-274790 A (published on October 18, 2007)

  However, since the piezoelectric element provided in the driving device described in Patent Document 1 or Patent Document 2 has a structure in which a piezoelectric body is bonded to both main surfaces of the shim material, the rigidity of the piezoelectric element depends on the rigidity of the shim material. Bending displacement is hindered. As a result, there arises a problem that the displacement amount of the piezoelectric element is reduced and the driving speed of the piezoelectric element is also reduced.

  Further, in order to manufacture the piezoelectric element, a step of attaching a piezoelectric body to the shim material is required, resulting in a problem that the cost of the piezoelectric element increases.

  Furthermore, since the piezoelectric element is manufactured by bonding a piezoelectric body to a shim material, the thickness of the piezoelectric element is increased. As a result, there arises a problem that it is difficult to reduce the size of the driving device including the piezoelectric element.

  On the other hand, in the driving device described in Patent Document 1 or Patent Document 2, it is inferred that these problems can be solved by using a piezoelectric element that does not use a shim material (hereinafter referred to as “shimless piezoelectric element”). . However, the piezoelectric element that is not reinforced by the shim material has low strength. For this reason, there is a problem that the productivity is easily lowered in the manufacturing process of the driving device. Moreover, the problem that it is easy to break by the impact by the fall etc. at the time of use arises.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a small and inexpensive bending displacement element that has both high driving speed and mechanical strength, and a driving device including the bending displacement element. As well as providing its use.

  In order to solve the above-described problems, a bending displacement element according to the present invention is a bending displacement element in which bending displacement is excited by applying a voltage, and the piezoelectric body is laminated via an electrode thinner than the piezoelectric body. A piezoelectric element, a friction member, and an intermediate member, wherein the intermediate member includes a fixed region and a functional region, and the fixed region is fixed to a free end that does not include a fixed end of the piezoelectric element, The functional region is provided with the friction member, and the intermediate member and the piezoelectric body are not electrically connected.

  According to the above configuration, the bending displacement element includes the piezoelectric element in which the piezoelectric body is laminated via the electrode thinner than the piezoelectric body, the intermediate member, and the friction member, and is provided in the functional region of the intermediate member. Is provided with the friction member, and the fixed region of the intermediate member is fixed to a region (free end) that does not hinder the displacement of the piezoelectric element. Therefore, a decrease in the amount of displacement of the bending displacement element can be suppressed. Further, since the fixed region of the intermediate member is fixed to the outer peripheral portion of the free end of the piezoelectric element, the mechanical strength of the piezoelectric element can be maintained without using a shim material as a reinforcing material. Therefore, it is not necessary to attach a piezoelectric body to the shim material when manufacturing the bending displacement element, the thickness of the bending displacement element can be reduced, and the manufacturing cost of the bending displacement element can be reduced. Further, since the intermediate member and the piezoelectric body are not electrically connected, the intermediate member can be easily assembled, and the manufacturing cost can be further reduced. As a result, a small and inexpensive bending displacement element having both high driving speed and mechanical strength can be provided.

  In the bending displacement element according to the present invention, the intermediate member may be bent in a direction different from the bending displacement direction of the bending displacement element.

  According to the above configuration, for example, when the bending displacement element according to the present invention is provided in the driving device, the driven body can be driven in a direction different from the bending displacement direction of the bending displacement element. Therefore, the position where the driven body is provided is not limited to the longitudinal direction of the bending displacement element. As a result, the drive device can be downsized.

  In the bending displacement element according to the present invention, the intermediate member extends in the longitudinal direction of the free end of the piezoelectric element, and the amount of displacement of the bending displacement element can be increased.

  According to the said structure, the displacement amount of a bending displacement element can further be expanded. Further, for example, when the bending displacement element according to the present invention is provided in the driving device, the contact position between the friction member and the driven body can be separated from the piezoelectric element, and therefore the position where the driven body is provided is the piezoelectric element. It is not limited to the vicinity of. As a result, the drive device can be downsized.

  In the bending displacement element according to the present invention, it is preferable that the intermediate member has a natural frequency having a frequency different from the natural frequency of the piezoelectric element.

  According to the above configuration, since the intermediate member is easy to process and has a high degree of freedom of shape as compared with the piezoelectric element, the natural frequency of the intermediate member can be arbitrarily changed. As a result, for example, when the bending displacement element according to the present invention is provided in the driving device, the driving frequency of the driving device can be arbitrarily changed.

  In the bending displacement element according to the present invention, the intermediate member may extend in the longitudinal direction of the free end of the piezoelectric element, and the position where the friction member is provided may be separated from the piezoelectric element.

  According to the above configuration, for example, when the bending displacement element according to the present invention is provided in the driving device, the contact position between the friction member and the driven body can be separated from the piezoelectric element, and thus the driven body is provided. The position is not limited to the vicinity of the piezoelectric element. As a result, the position where the driven body is provided can be freely selected according to the purpose.

  A driving apparatus according to the present invention includes the bending displacement element according to the present invention and a driven body that is driven in conjunction with the bending displacement of the bending displacement element.

  The drive device according to the present invention includes the bending displacement element according to the present invention. As a result, it is possible to provide a small and inexpensive driving device having both high driving speed and mechanical strength.

  An image pickup apparatus according to the present invention includes the drive device according to the present invention, an optical system that forms an image of an object to be imaged, and an image pickup element that converts an image formed by the optical system into an electrical signal. And the to-be-driven body with which the said drive device is equipped has the said optical system, It is characterized by the above-mentioned.

  An imaging apparatus according to the present invention includes a drive device according to the present invention. As a result, it is possible to provide a small and inexpensive imaging device that has both high driving speed and mechanical strength.

  An electronic apparatus according to the present invention includes the drive device according to the present invention or the imaging device according to the present invention.

  An electronic apparatus according to the present invention includes the drive device or the imaging device according to the present invention. As a result, a small and inexpensive electronic device having both high driving speed and mechanical strength can be provided.

  A bending displacement element according to the present invention is a bending displacement element in which bending displacement is excited by applying a voltage, and a piezoelectric element in which a piezoelectric body is laminated via an electrode thinner than the piezoelectric body, and a friction member And an intermediate member, and the intermediate member includes a fixed region and a functional region, and the fixed region is fixed to a free end that does not include a fixed end of the piezoelectric element, and the friction member is provided in the functional region. The intermediate member and the piezoelectric body are not electrically connected.

  Therefore, it has a sufficient amount of displacement and can maintain sufficient mechanical strength without using shim as a reinforcing material, so it is a small and inexpensive bending displacement that combines high driving speed and mechanical strength. There is an effect that it is possible to provide an element and a driving apparatus including the bending displacement element, and an imaging apparatus and electronic apparatus including the driving apparatus.

It is a figure which shows typically the structure of the bending displacement element which is embodiment of this invention. It is sectional drawing which shows typically the structure of the piezoelectric element with which the bending displacement element which is embodiment of this invention is provided. It is a figure which shows typically the structure of the bending displacement element provided with the intermediate member which combines the function which expands the displacement amount of a bending displacement element, and the function which separates the position in which a friction member is provided from a piezoelectric element. It is a figure which shows typically the structure of the drive device which is embodiment of this invention. (A) is a side view which shows typically the structure of the drive device which is embodiment of this invention, (b) is the front view.

  An embodiment of the present invention will be described as follows, but the present invention is not limited to this.

  In the present specification, “A to B” indicating a range indicates “A or more and B or less”.

[1. Bending displacement element
In the bending displacement element according to the present invention, bending displacement is excited by applying a voltage. An example of the configuration of the bending displacement element 7 according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram schematically showing a configuration of a bending displacement element 7 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the configuration of the piezoelectric element provided in the bending displacement element according to the embodiment of the present invention.

  The bending displacement element 7 includes a piezoelectric element 5 in which a piezoelectric body 5 a is laminated via an electrode thinner than the piezoelectric body, a friction member 3, and an intermediate member 4. The intermediate member 4 includes a fixed area 4a and a functional area 4b. The fixed region 4 a of the intermediate member 4 is fixed to a free end that does not include the fixed end of the piezoelectric element 5. Further, the friction member 3 is provided in the functional region 4 b of the intermediate member 4.

  The “fixed end” of the piezoelectric element 5 refers to a portion that is fixed to the housing or the like of the driving device and that does not cause bending displacement when a voltage is applied. On the other hand, the “free end” of the piezoelectric element 5 refers to all portions where bending displacement occurs, that is, all portions other than the “fixed end”.

  When a voltage is applied to the piezoelectric element 5, the free end of the piezoelectric element 5 is bent and displaced in a direction substantially parallel to the XY plane with the fixed end as an axis, as indicated by an arrow (direction 1) in FIG. In this specification, the direction in which the free end is bent and displaced as indicated by the arrow (direction 1) in FIG. 1 is referred to as a “bending displacement direction”.

  The intermediate member 4 includes a fixed region 4a that is fixed to the piezoelectric element 5 and a functional region 4b that is not in direct contact with the piezoelectric element 5 but to which the friction member 3 is fixed. Further, the intermediate member 4 and the piezoelectric element 5 are not electrically connected, and the fixing region 4a of the intermediate member 4 is bonded and fixed to the main surface of the piezoelectric element 5 with an adhesive or the like.

  The fixed region 4a of the intermediate member 4 is not attached to substantially the entire surface of the piezoelectric element 5 like the shim material in the conventional piezoelectric element, but is fixed to a part of the free end excluding the fixed end of the piezoelectric element 5, It is preferable that the element 5 is disposed so as not to hinder bending displacement. As will be described later, the piezoelectric element 5 is a brittle material including a piezoelectric body 5a made of piezoelectric ceramic, and the corners and sides of the piezoelectric element 5 are easily broken and damaged when a physical impact is applied. Therefore, the intermediate member 4 in the bending displacement element 7 not only connects the friction member 3 and the piezoelectric element 5 but also protects a region including the corners and sides of the piezoelectric element 5 (hereinafter referred to as “outer peripheral portion”). From the viewpoint of improving the mechanical strength of the piezoelectric element 5, it is more preferable to have a shape that is attached to only a part of the outer peripheral portion of the free end of the piezoelectric element 5.

  Specifically, the outer peripheral portion of the piezoelectric element 5 is 0 to 30% from the side parallel to the X direction of the free end when the length of the free end of the main surface of the piezoelectric element 5 is 100%. And the range of 0 to 15% from the side parallel to the Y direction of the free end when the length in the width direction of the free end of the main surface of the piezoelectric element 5 is 100%, and the piezoelectric parallel to the XY plane When the length in the longitudinal direction of the free end of the side surface of the element 5 is 100%, the range of 0 to 30% from the side parallel to the X direction of the free end and the thickness direction of the piezoelectric element 5 parallel to the XZ plane. Refers to the entire side.

  In addition, the functional region 4b of the intermediate member 4 has a function of transmitting the bending displacement of the piezoelectric element 5 to the friction member 3, but other functions can be given by changing the shape thereof. For example, as shown in FIG. 1, the intermediate member 4 has a plate shape in which a “cut” is formed on one side of the functional region 4 b, and the “cut” is parallel to the Z-direction side on the free end side of the piezoelectric element 5. When the intermediate member 4 is arranged so that the intermediate member 4 moves in a seesaw manner as the piezoelectric element 5 bends, the piezoelectric element 5 is bent and displaced in a direction substantially parallel to the XY plane. On the other hand, the friction member 3 provided in the functional region 4b of the intermediate member 4 and the functional region 4b of the intermediate member 4 is bent and displaced in a direction substantially parallel to the XZ plane as shown by an arrow (direction 2) in FIG.

  That is, the intermediate member 4 having a shape as shown in FIG. 1 has a function (displacement direction conversion function) that can displace the friction member 3 in a direction different from the bending displacement direction of the bending displacement element 7. . By using the intermediate member 4 provided with such a displacement direction conversion function, the thickness direction (X direction) of the bending displacement element 7 in the driving device 10 shown in FIGS. The bending displacement element 7 can be arranged so as to be perpendicular to the movement direction (Z direction). As a result, the drive device 10 can be downsized in the width direction (X direction).

  Another configuration of the intermediate member 4 will be further described with reference to FIG. FIG. 3 is a diagram schematically illustrating a configuration of a bending displacement element including an intermediate member that has a function of expanding the displacement amount of the bending displacement element and a function of separating the position where the friction member is provided from the piezoelectric element. . In the intermediate member 4 shown in FIG. 3A, the functional region 4 b of the intermediate member 4 is formed so that the friction member 3 can be arranged at a position extending in the longitudinal direction of the free end of the piezoelectric element 5.

  If the intermediate member 4 is shaped as shown in FIG. 3A, for example, in the driving device 10 shown in FIGS. 4 and 5 described later, the arrangement of the driven body contact portion 2a of the driven body 2 is piezoelectric. It is not limited to the vicinity of the element 5. For example, when the driven body contact portion 2a of the driven body 2 and the piezoelectric element 5 cannot be disposed close to each other due to the thickness of the piezoelectric element 5, the piezoelectric element 5 is formed of a plate-like member thinner than the piezoelectric element 5. The functional region 4b of the intermediate member 4 may be extended. By using the bending displacement element 7 provided with the intermediate member 4 having the functional region 4b having a shape as shown in FIG. 3A, the driving device 10 can be reduced in the width direction (X direction). .

  Further, in the functional region 4 b of the intermediate member 4 shown in FIG. 3A, the surface where the driven member contact portion 2 a of the driven member 2 and the friction member 3 come into contact with the main surface of the bending displacement element 7. The friction member 3 is provided so as to be parallel to each other. On the other hand, in the functional region 4 b of the intermediate member 4 shown in FIG. 3B, the surface where the driven member contact portion 2 a of the driven member 2 and the friction member 3 come into contact with the main surface of the bending displacement element 7. The friction member 3 is provided so as to be vertical (thickness direction of the bending displacement element 7). The intermediate member 4 having such a shape can be suitably used when the driven body 2 is driven in the thickness direction of the bending displacement element 7.

  Usually, the piezoelectric element 5 used in the driving device has a thickness of 1 mm or less. In particular, in a camera module or the like for a mobile phone, a very thin piezoelectric element 5 having a thickness of about 0.5 mm is used from the viewpoint of downsizing the driving device. In such a thin piezoelectric element 5, the friction member 3 is accurately placed so that the surface of the driven body 2 where the driven member contact portion 2 a contacts the friction member 3 is parallel to the thickness direction of the piezoelectric element 5. It is difficult to install. In such a case, if a surface parallel to the thickness direction of the piezoelectric element 5 is formed in the functional region 4 b of the intermediate member 4, the size of this surface can be made larger than the thickness of the piezoelectric element 5. The friction member 3 can be easily attached and the productivity is improved.

  3A and 3B, the functional region 4b of the intermediate member 4 extends in the longitudinal direction of the free end of the piezoelectric element 5, so that the friction member 3 is the end of the free end of the piezoelectric element 5. To the functional region 4b. In this case, if the length of the functional region 4b in the longitudinal direction is a, the displacement amount of the friction member 3 is larger asin θ compared to the case where the functional region 4b is not extended. Therefore, if the intermediate member 4 shown in FIGS. 3A and 3B is used, the bending displacement amount of the bending displacement element 7 can be easily increased.

  In addition, by setting the shape and material of the intermediate member 4 so that the natural frequency of the functional region 4 b is different from the natural frequency of the piezoelectric element 5 in the functional region 4 b of the intermediate member 4, the driving device 10. The drive frequency is near the natural frequency of the intermediate member 4. Therefore, the drive frequency of the drive device 10 can be arbitrarily changed.

  In order to change the driving frequency of the driving device 10 by changing the natural frequency of the piezoelectric element 5, it is necessary to change the shape and material of the piezoelectric element 5. However, there are limitations on the arrangement space and thrust of the piezoelectric element 5, and it is not easy to change the natural frequency of the piezoelectric element 5. On the other hand, since the intermediate member 4 is formed from a material that can be easily processed (for example, stainless steel, aluminum, etc.), the intermediate member 4 has a higher degree of freedom in shape and material than the piezoelectric element 5. Therefore, it is easy to change the natural frequency of the intermediate member 4. Therefore, the drive frequency of the drive device 10 can be easily changed by changing the shape of the intermediate member 4.

  Specifically, the natural frequency of the intermediate member 4 is set to a desired value by changing the thickness of the intermediate member 4, changing the length of the functional region 4 b in the longitudinal direction, or changing the material of the intermediate member 4. Can be set.

  The intermediate member 4 is preferably made of a metal having elasticity because it absorbs a drop impact and hardly causes damage such as plastic deformation and peeling of the intermediate member 4. The “elastic metal” is not particularly limited, and examples thereof include stainless steel (SUS), aluminum, and phosphor bronze.

  Next, the piezoelectric element 5 used in this embodiment will be described based on the cross-sectional view of FIG. FIG. 2 is a cross-sectional view schematically showing the configuration of the piezoelectric element provided in the bending displacement element according to the embodiment of the present invention. The piezoelectric element 5 has a structure in which piezoelectric bodies 5a made of a piezoelectric ceramic such as lead zirconate titanate (PZT) are stacked via electrodes. The electrodes have three types of shapes, that is, an electrode 5c, an electrode 5d, and a central electrode 5b. The electrodes having the same shape use through electrodes 5e in the stacking direction indicated by arrows in FIG. Are electrically connected.

  Furthermore, the piezoelectric body 5a is subjected to polarization processing at the electrode 5c and the electrode 5d using the central electrode 5b as a ground electrode. Specifically, by applying voltages between the central electrode 5b and the electrode 5c and between the central electrode 5b and the electrode 5c, displacements having different bending directions can be obtained.

  As the number of stacked piezoelectric bodies 5a, for example, a stack of about 4 to 20 piezoelectric bodies 5a can be used. However, the number of stacked piezoelectric bodies 5a is appropriately determined depending on the thickness and thrust required for the bending displacement element 7, and the present invention is not limited to the above-described configuration.

  The thickness of the piezoelectric body 5a is preferably in the range of 10 to 40 μm. Further, as the electrode 5c, the electrode 5d, and the center electrode 5b, it is preferable to use thin films such as copper, aluminum, and silver that are thinner than the piezoelectric body 5a. Specifically, the thickness of each of the electrode 5c, the electrode 5d, and the center electrode 5b is preferably 5 μm or less.

  In such a piezoelectric element 5, the piezoelectric body 5a is not bonded using a shim material unlike the conventional piezoelectric element. Therefore, in the bending displacement element 7 having such a piezoelectric element 5, the driving displacement amount of the bending displacement element 7 due to the rigidity of the shim material does not occur. Further, since the step of bonding the piezoelectric body 5a and the shim material is not required when manufacturing the piezoelectric element 5, the production cost of the bending displacement element 7 can be suppressed.

  The bending displacement element according to the present invention is not limited to being provided in a driving device, and can be suitably used for, for example, an ink jet recording head, a fuel cell, a medical small pump, and the like.

[2. (Driver)
An example of the configuration of the drive device 10 according to the embodiment of the present invention will be described based on a perspective view shown in FIG. 4, a side view shown in FIG. 5A, and a front view shown in FIG. The bending displacement element according to the present invention is the same as that described in “1. Bending displacement element”, and is omitted here. In the following description, as shown in the figure, the direction of movement of the driven body 2 is the Z direction, the longitudinal direction of the bending displacement element 7 in a stationary state, and the direction perpendicular to the Z direction. Is a thickness direction of the bending displacement element 7 in a stationary state, and a direction perpendicular to the Y direction and the Z direction is an X direction.

  4 and 5 includes a bending displacement element 7 in which bending displacement is excited by applying a voltage, a fixing member 6a that fixes one end of the bending displacement element 7, and bending. A driven body 2 that is in frictional contact with the friction member 3 provided in the displacement element 7, a pressurizing member 1 that biases the driven body contact portion 2 a of the driven body 2 toward the friction member 3, and a driven body 2. Is provided with a guide shaft 8 and a housing 6.

  In the driving device 10, when a voltage is applied to the bending displacement element 7, the bending displacement element 7 is displaced in a direction substantially parallel to the XY plane. A friction member 3 is provided at the free end of the bending displacement element 7 via an intermediate member 4. With the displacement of the friction member 3, the contact member 2 d provided on the driven body contact portion 2 a formed in a protruding shape from the driven body 2 and the friction member 3 are in frictional contact. As a result, the driven body 2 is driven by sliding in the Z direction along the guide shaft 8.

  In the embodiment shown in FIGS. 4 and 5, the bending displacement element 7 is bonded and fixed to the YZ plane of the fixing member 6 a provided on the housing 6, and a part of the principal surface of the bending displacement element 7 is fixed. It arrange | positions so that a moving direction (Z direction) and the main surface of the bending displacement element 7 may become parallel.

  When the voltage is applied to the bending displacement element 7, the bending displacement is excited. Here, the “voltage” applied to the bending displacement element 7 is not particularly limited, and may be appropriately selected according to the purpose, but is normally 1.5V to 30V. As a method for controlling the voltage applied to the bending displacement element 7, a conventionally used method may be used.

  Both end portions of the pressurizing member 1 are fixed to the driven body pressurizing portion 2 b of the driven body 2 and the casing pressurizing portion 6 b of the housing 6. The pressurizing member 1 may be a member having elasticity such as a coil spring. Between the pressurizing member 1 and the friction member 3, a driven body contact portion 2a of the driven body 2 and a contact member 2d bonded and fixed to the driven body contact portion 2a are sandwiched and arranged. The pressurizing member 1 is configured to constantly urge the driven body contact portion 2a of the driven body 2 toward the friction member 3 (contact member 2d). With such a configuration, the driven body 2 can maintain a stable position.

  The driven body 2 is a member that moves in conjunction with the bending displacement of the bending displacement element 7, and the driven body contact portion 2a formed in a protruding shape from the driven body 2 and the friction at the driven body contact portion 2a. And a contact member 2d formed on the member 3 side. The driven body contact portion 2a and the contact member 2d may be provided so as to move integrally with the driven body 2. For example, it may be bonded and fixed to the driven body 2 or may be formed integrally with the driven body 2, but the present invention is not limited to this.

  The guide shaft 8 may be a guide for smoothly moving the driven body 2 along the Z direction. In the present embodiment, the guide shaft 8 is a shaft provided perpendicular to the XY plane of the housing 6 in the Z direction, and the guide shaft 8 is passed through a shaft hole provided in the driven body 2. The guide shaft 8 is not limited to a shaft as long as it holds the driven body 2, and may be, for example, a linear guide or a leaf spring.

  Although not shown in FIG. 4, the driving device 10 may have a drive mechanism that controls the voltage applied to the bending displacement element 7 so that the reciprocating bending speed of the bending displacement element 7 is different. In this drive mechanism, the frictional force acting between the driven body 2 and the friction member 3 is changed by the difference in the reciprocating bending speed of the bending displacement element 7, and the frictional movement difference between the driven body 2 and the friction member 3 is changed. By causing the displacement, the displacement amount (movement amount) in the Z direction of the driven body 2 can be changed.

  Specifically, the voltage applied to the bending displacement element 7 has a rectangular wave shape with different duty ratios, and a speed difference is provided by the reciprocation of the bending displacement element 7. On the slow speed side, the driven body 2 is moved and displaced by the frictional force acting between the driven body 2 and the friction member 3. On the other hand, on the higher speed side, slippage occurs between the driven body 2 and the friction member 3, and the displacement is reduced. Due to this phenomenon, the driven body 2 can be moved in one direction. In addition, the driven body 2 can be moved in the reverse direction by reversing the duty ratio, and the driven body 2 can be moved in any direction in the Z direction by controlling the applied voltage. A drive frequency for reciprocally bending the bending displacement element 7 is usually several kHz or higher, but preferably an inaudible ultrasonic frequency (20 kHz or higher) is used.

[3. Imaging device]
An example of the configuration of the imaging apparatus according to the embodiment of the present invention will be described based on the front view shown in FIG. An image pickup apparatus according to an embodiment of the present invention includes a drive device according to the present invention, an optical system that forms an image of an object to be imaged, and an image sensor that converts an image formed by the optical system into an electrical signal. It has. The drive device according to the present invention is as described in “2. Drive device”, and is omitted here.

  When the driving device 10 shown in FIG. 4 is applied to a camera module (lens driving of an imaging device such as a camera), an annular lens mounting portion 2c is provided at the center of the driven body 2, thereby providing a lens barrel and a lens. The driven body 2 can function as a lens holding frame that directly holds an optical system such as the above. When the lens is attached to the lens mounting portion 2c of the driven body 2, the moving direction (Z direction) of the driven body 2 is the optical axis direction of the lens. Further, when the driven body 2 is driven in the optical axis direction (Z direction) by the driving mechanism of the driving device 10, an autofocus (AF) operation of the lens attached to the lens attaching portion 2 c can be realized, and the driving device 10. Can be suitably used as an AF driving device for the camera module.

[4. Electronics〕
An electronic apparatus according to the present invention includes the drive device or the imaging device described above. Such an electronic device is not particularly limited, and examples thereof include a mobile phone, a game machine, a PDA, and a personal computer.

  The drive device according to the present invention is as described in “2. Drive device”, and the image pickup device according to the present invention is as described in “3.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The bending displacement element according to the present invention can be suitably used for, for example, a mechanical shutter such as a camera module, an ink jet recording head, a fuel cell, a medical small pump, and the like. Therefore, the present invention can be widely used in all electronic equipment industries that manufacture electronic equipment having a bending displacement element.

  Moreover, the drive device provided with the bending displacement element concerning this invention can be utilized suitably for imaging devices or electronic devices, such as a camera module, for example. Therefore, it can be widely used in all electronic equipment industries that manufacture imaging devices or electronic equipment using a driving device.

DESCRIPTION OF SYMBOLS 1 Pressurization member 2 Driven body 2a Driven body contact part 3 Friction member 4 Intermediate member 4a Fixed area | region 4b Functional area | region 5 Piezoelectric element 5a Piezoelectric body 5b Center electrode 5c Electrode 5d Electrode 5e Through-electrode 6a Fixed member 7 Bending displacement element 8 Guide shaft 10 Drive device

Claims (8)

A bending displacement element in which bending displacement is excited by applying a voltage;
The bending displacement element includes a piezoelectric element in which a piezoelectric body is laminated via an electrode thinner than the piezoelectric body, a friction member, and an intermediate member,
The intermediate member is composed of a fixed region and a functional region,
The fixed region is fixed to a free end not including the fixed end of the piezoelectric element,
The functional region is provided with the friction member,
The bending displacement element, wherein the intermediate member and the piezoelectric body are not electrically connected.   The bending displacement element according to claim 1, wherein the intermediate member is bent in a direction different from a bending displacement direction of the bending displacement element.   2. The bending displacement element according to claim 1, wherein the intermediate member extends in a longitudinal direction of a free end of the piezoelectric element and can increase a displacement amount of the bending displacement element.   The bending displacement element according to claim 1, wherein the intermediate member has a natural frequency having a frequency different from a natural frequency of the piezoelectric element.   2. The bending displacement element according to claim 1, wherein the intermediate member extends in a longitudinal direction of a free end of the piezoelectric element and separates a position where the friction member is provided from the piezoelectric element. A bending displacement element according to any one of claims 1 to 5,
And a driven body that is driven in conjunction with the bending displacement of the bending displacement element. A drive device according to claim 6;
An optical system for imaging an object to be imaged;
An image sensor that converts an image formed by the optical system into an electrical signal;
An imaging apparatus, wherein a driven body provided in the driving apparatus holds the optical system.   An electronic apparatus comprising the drive device according to claim 6 or the imaging device according to claim 7.

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