JP2004153999A - Piezoelectric actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the piezoelectric actuator so as to obtain accurate drive control, by attaining stabilization of frictional force between a stationary fixed member and a moving body. <P>SOLUTION: In the piezoelectric actuator provided with a piezoelectric element 2, a moving body 3 driven by this piezoelectric element 2, and a stationary fixed member 4 friction engaged with this moving body 3, the moving body 3 is constituted in a cylindrical shape covering the piezoelectric element 2, this cylindrical outer surface is constituted so as to be fitted to the stationary fixed member 4, friction force between the fixed member 4 and the cylindrical outer surface shape of the moving body 3 is stabilized so as to attain stabilization of operatioin. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a piezoelectric actuator that drives a driven part using a deformation operation of a piezoelectric element.

  In general, a piezoelectric actuator includes a piezoelectric element, a stationary body and a movable body that slides, and has a structure in which the movable body is connected to a driven part. For example, in Japanese Unexamined Patent Publication No. 6-315282, a moving body is connected to an optical element provided on a lens portion, and the moving body is slidably held with a predetermined frictional force against a fixed member. A beam-like leg is provided.

  When manufacturing such a conventional piezoelectric actuator, the frictional force when the tip of the leg portion slides on the fixed member does not always have a constant value due to a manufacturing error, and variation occurs for each product. In addition, the difference in the frictional force between the fixed member and the moving body for each product causes a difference in the amount of movement of the moving body with respect to the distal end body provided with the fixed member during driving, thereby enabling accurate drive control. The problem that it became difficult had arisen.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a piezoelectric actuator which stabilizes a frictional force between a stationary fixing member and a moving body and enables accurate drive control. It is in.

  The present invention provides a piezoelectric element, a moving body fixed to an end of the piezoelectric element, a stationary fixing member that frictionally engages with the moving body, and abruptly deforms the piezoelectric element. A piezoelectric actuator comprising: a driving unit configured to apply a shock to the moving body and overcome the frictional engagement between the moving body and the stationary fixed member to move the moving body with respect to the stationary fixed member. Is configured to have a cylindrical shape covering the piezoelectric element, and the cylindrical outer surface is configured to fit with the stationary fixing member. The frictional force between the fixing member and the cylindrical outer surface shape of the moving body is To stabilize the operation.

  According to the present invention, since the movable body has a cylindrical shape, the frictional force between the stationary member and the movable body can be stabilized without the center of the actuator being displaced, and accurate drive control can be performed.

<First embodiment>
A first embodiment of the present invention will be described with reference to FIG. FIG. 1A is a vertical cross-sectional view of the piezoelectric actuator, and FIG. 1B is a perspective view in which members before the assembly of the piezoelectric actuator are arranged.

(Constitution)
The piezoelectric actuator 1 according to this embodiment includes a piezoelectric element 2, a moving body 3 adhesively fixed to one end of the piezoelectric element 2, and a stationary fixed member 4 slidably engaged with the moving body 3. Consists of

  The piezoelectric element 2 is a laminated piezoelectric element formed by laminating a plurality of piezoelectric bodies and electrodes. The piezoelectric element 2 constitutes an impact force generating section that applies a driving voltage to its electrode to cause the piezoelectric body to mechanically expand and contract in the longitudinal direction of the lamination to give an instantaneous impact to the moving body 3. are doing. Lead wires 5 are connected to the electrodes of the piezoelectric element 2 by soldering. Then, as described later, when a voltage is applied to the piezoelectric element 2 through the lead wire 5, the piezoelectric element 2 is rapidly deformed, and the piezoelectric element applies an impact to the moving body 3, thereby causing the moving body 3 to impact with the moving body 3. Drive means for moving the movable body 3 with respect to the fixed member 4 by overcoming frictional engagement with the fixed member 4 is provided. The lead wire 5 is connected to a control device (not shown) of the driving means.

  The moving body 3 is provided with a band-shaped leaf spring 7 and an annular centering member 8. The leaf spring 7 is formed by bending a band-shaped leaf spring material into two in the center, and the folded middle portion is used as a mounting portion 9, and the bent both end pieces are pressed against the inner surface of the fixing member 4 respectively. A leg 10 made of a beam is formed. Each leg 10 is biased by spring elasticity so as to expand outward. The distal end of each leg 10 presses against the inner surface of the fixing member 4 to form a sliding portion 11 that frictionally engages.

  The centering member 8 is fitted into both of the base ends of the legs 10. The centering member 8 is formed with a rectangular fitting hole 12 into which both the base end portions of the legs 10 are fitted. The outer diameter of the centering member 8 is loosely fitted and slidable to such a degree as to lightly contact the inner surface of the cylindrical fixing member 4. The sliding resistance of the centering member 8 with respect to the fixed member 4 is set to a value sufficiently smaller than the frictional force between the sliding portion 11 of the moving body 3 and the fixed member 4. The fitting hole 12 of the centering member 8 is formed coaxially with the center of the inner hole of the fixing member 4. The centering member 8 constitutes a centering mechanism for limiting the centering of the piezoelectric actuator 1 by slidingly contacting the inner surface of the fixed member 4 during its movement.

  Further, the centering member 8 constitutes a frictional force adjusting means for adjusting a frictional force between the moving body 3 and the fixed member 4 by changing a position where the centering member 8 is fitted to the leg 10 as described later. It also serves as an adjusting member.

  The base width of each leg 10 fitted into the fitting hole 12 of the centering member 8 is such that the facing width before the centering member 8 is assembled to the base 10 is larger at the distal end side than at the base side. The frictional force adjusting portion 13 is formed by this region. As shown in FIG. 1B, the dimensional relationship between the width A at the most proximal position of the frictional force adjusting unit 13 and the width B at the most extreme position is such that A <B.

  That is, each leg 9 has a linear gradient in the area of the frictional force adjusting portion 13, and further bends and extends outward from the most distal end position of the frictional force adjusting portion 13 at the most distal end. A sliding portion 11 is formed. The sliding surface of the sliding portion 11 of each leg 9 is formed to have substantially the same shape as the sliding surface of the inner surface of the cylindrical fixing member 4 sliding on the sliding portion 11.

  An insulating member 16 is provided on each side surface of the piezoelectric element 2 located on each leg 10 side of the moving body 3. The insulating member 16 is preferably made of an electrically insulating material such as ceramics or plastic. As the plastic, those formed in a sheet shape such as polyimide or tetrafluoroethylene are preferable. It may be formed by coating with an electrically insulating coating material. In the present embodiment, nothing is provided on the other end of the piezoelectric element 2 on the side opposite to the fixed portion side of the moving body 3, but a weight called an inertial body may be provided.

  A mounting portion 9 of the leaf spring 7 of the moving body 3 is fixed to one end of the piezoelectric element 2 so as to be fitted therein, and a connecting arm portion of a driven body is mounted on an outer portion of the mounting portion 9. It is fitted and fixed by being fitted and elastically coupled in a state of being inserted into a connection hole 18 formed in 17. For this reason, installation and removal are easy.

  As described above, the connection between the connection arm 17 of the driven body and the piezoelectric actuator 1 is performed in a state where the mounting portion 9 of the leaf spring 7 having a leg structure is inserted into the connection hole 18 formed in the connection arm 17. Although they are elastically fitted, the elastic coupling force is set to be larger than the force generated by the piezoelectric actuator 1.

  Of course, the connection arm 17 of the driven body and the piezoelectric actuator 1 may be connected by other fixing means such as adhesion.

  The driven body driven by the piezoelectric actuator 1 is, for example, a lens or a mirror of an optical device. Further, an XY stage or the like that requires a minute operation may be used. Examples of the lens of the optical device include a zoom lens, a focus lens, and the like such as a microscope, a camera, and an endoscope.

(Action)
The operation of the piezoelectric actuator 1 will be described. Since the moving body 3 is inserted into the fixed member 4 and the sliding portion 11 of the leg 10 of the moving body 3 hits against the inner surface of the fixed member 4 and each leg 10 is elastic. As a result, a static friction force is generated between the inner surface of the fixing member 4 and the sliding portion 11 of the leg 10.

  The centering member 8 is slidably fitted into the fixed member 4, moves integrally with the moving body 3, and slides on the inner surface of the fixed member 4 at the time of the movement, whereby the piezoelectric actuator 1 Prevent run-out.

  Next, a method of adjusting the frictional force will be described. The centering member 8 is positioned so that the fitting hole 12 is fitted to the frictional force adjusting portion 13 of the leg 10 of the moving body 3, and the centering member 8 is positioned at the base of the frictional force adjusting portion 13. If it is fixed to the end side (the A side in FIG. 1B), the opening of the leg 10 of the moving body 3 is increased, and the deflection of the leg 10 is also increased. The frictional force of the sliding portion 11 that contacts the inner surface of the fixed member 4 increases.

  Conversely, if the centering member 8 is moved toward and fixed to the distal end side (the side B in FIG. 1B) of the frictional force adjusting portion 13 of the moving body 3, the opening of the leg 10 becomes small, 10 also reduces the frictional force of the sliding portion 11 that comes into contact with the inner surface of the fixed member 4. In this manner, the deflection of the leg 10 is reduced by the centering member 8 provided on the moving body 3. The frictional force of the sliding portion 11 that comes into contact with the inner surface of the fixed member 4 is adjusted with restriction.

  Next, the operation of the piezoelectric actuator 1 will be described. First, when a voltage having a waveform that rapidly expands is applied to the piezoelectric element 2 from the control device of the driving means through the lead wire 5, an inertial force is generated in the piezoelectric element 2, and an impact force is applied to the moving body 3. Greatly increases. Since this inertial force is larger than the static friction force generated in the sliding portion 11 of the moving body 3, the moving body 3 slightly moves to the left in FIG. Then, when the piezoelectric element 2 is slowly contracted, the moving body 3 stops at that position because the inertial force generated at this time is smaller than the static friction force.

  By repeatedly performing this step, the moving body 3 of the piezoelectric actuator 1 moves together with the piezoelectric element 2. Since the actual driving frequency of the driving voltage here is as high as several tens of kHz, the piezoelectric actuator 1 can operate smoothly in total. In order to move the piezoelectric actuator 1 in the opposite direction, a voltage having a waveform that reverses the direction in which the above-described inertial force is generated may be applied.

  If an inertia body (not shown) is provided at the end of the piezoelectric element 2 opposite to the moving body 3, the inertia increases the inertia force and the driving force.

(effect)
By selecting the installation position of the centering member 8, the frictional force of the moving body 3 on the fixed member 4 can be easily adjusted. For this reason, it is possible to provide a piezoelectric actuator that can stabilize performance without causing variation in frictional force between the individual piezoelectric actuators 1 and that can perform accurate drive control. Further, the frictional force between the moving body 3 and the fixed member 4 can be easily adjusted, and readjustment can be easily performed.

  In addition, since the centering member 8 prevents the center of the piezoelectric actuator 1 from falling down, the operation of the piezoelectric actuator 1 is stabilized without the moving body 3 of the piezoelectric actuator 1 getting stuck on the fixed member 4 or the like. A reliable piezoelectric actuator 1 can be provided.

  In this embodiment, since the frictional force adjusting mechanism and the centering mechanism by the centering member 8 are also used, the number of parts is reduced, the assembly is easy, and the manufacturing cost of the piezoelectric actuator 1 can be reduced. it can.

  Further, since the attachment portion 9 of the piezoelectric actuator 1 can be elastically connected only by being pushed into the connection hole 18 formed in the connection arm portion 17 of the driven body, the connection and assembly thereof are easy.

  Since the insulating member 16 is provided between the frictional force adjusting portion 13 of the moving body 3 and the piezoelectric element 2, the moving body 3 does not directly contact the portion of the piezoelectric element 2 and the Be safe.

Since the frictional force adjusting unit 13 of the moving body 3 suppresses the piezoelectric element 2 via the insulating member 16, the piezoelectric element 2 is less likely to be broken by an impact, and the durability of the piezoelectric actuator 1 is improved.
In the case where another inertia member is provided, the inertia force generated when the piezoelectric element 2 is rapidly deformed increases, and the driving force increases.

<Second embodiment>
A second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a longitudinal sectional view of the piezoelectric actuator.

(Constitution)
The piezoelectric actuator 20 according to this embodiment includes a piezoelectric element 21, a moving body 22 provided at one end of the piezoelectric element 21, and a cylindrical fixing member 23 slidably and frictionally engaged with the moving body 22. , And a connecting member 24 for elastically connecting the moving body 22 and the piezoelectric element 21. An output shaft (not shown) is attached to the moving body 22, and the output shaft is fixed to a driven body (not shown). The driven body is, for example, a lens or a mirror of an optical device, but may be an XY stage or the like that requires a minute operation. The lens of the optical device is, for example, a zoom lens, a focus lens, a lens for illumination, or the like, such as a microscope, a camera, or an endoscope.

  The piezoelectric element 21 is a laminated piezoelectric element, and a lead wire 25 is connected to its electrode. The lead wire 25 is connected to a control device (not shown) of the driving means.

  Further, a connecting member (not shown) made of an elastic member may be provided between the moving body 22 and the lead wire 25 to elastically connect the both.

  The moving body 22 includes a piezoelectric element fixing portion 26 adhered and fixed to one end of the piezoelectric element 21, at least two legs 27 extending from the piezoelectric element fixing portion 26 in a cantilever shape, And a sliding portion 28 provided at each of the extending ends. The leg portion 27 has a cantilever shape with respect to the piezoelectric element fixing portion 26, and the sliding portion 28 is formed at the tip thereof. The sliding portion 28 is formed in a shape that can smoothly slide on the inner surface of the fixed member 23.

  The inner surface of the fixing member 23 is formed smoothly so that it can slide on the moving body 22 smoothly. In addition, the outer shape of the fixing member 23 may be any shape, and any shape may be used as long as it is easy to assemble when driving the driven body (not shown).

  The coupling member 24 is provided between the leg 27 of the moving body 22 and the piezoelectric element 21. As a material of the coupling member 24, an elastic body is preferable. For example, a silicone adhesive or rubber is preferable. The coupling member 24 is configured to have better thermal conductivity than air. Further, the coupling member 24 is preferably made of an electrically insulating material.

  The elastic force of the coupling member 24 is set to be sufficiently smaller than the force generated by the piezoelectric element 21. The connecting member 24 may be connected to the entire leg 27 as shown in FIG. 2, or may be a part thereof. In particular, if it is a part, it is preferable that the leg 27 is on the sliding portion 28 side. Further, the coupling member 24 may be fixed to the moving body 22 so as to elastically contact the piezoelectric element 21.

  Although nothing is provided at the other end of the piezoelectric element 21 in this embodiment, a weight called an inertial body may be provided.

(Action)
The piezoelectric element 21 is elastically coupled and pressed by the coupling member 24 provided on the moving body 22, and is in a state of covering and protecting the piezoelectric element 21. The operation of the piezoelectric actuator 20 is the same as that described in the first embodiment, and a description thereof will be omitted. When an inertial body is provided in the piezoelectric element 21, the inertial force at the time of its operation increases, and the driving force increases.

(effect)
Since the piezoelectric element 21 is elastically pressed by the coupling member 24, the piezoelectric element 20 does not break when an impact is applied to the piezoelectric actuator 20, so that the shock resistance is improved and the quality of the piezoelectric actuator 20 is improved. .

  Since a material having good thermal conductivity is used for the coupling member 24, the heat generated in the piezoelectric element is quickly dissipated, and the performance of the piezoelectric actuator 20 is not deteriorated by the heat, thereby maintaining the quality.

  Since an electrically insulating material is used for the coupling member 24, the piezoelectric element 21 and the leg 27 do not come into electrical contact with each other, thereby enhancing safety.

<Third embodiment>
A third embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a longitudinal sectional view of the piezoelectric actuator, and FIG. 4 is a sectional view taken along line AA in FIG.
(Constitution)
The piezoelectric actuator 30 according to this embodiment includes a piezoelectric element 31, a moving body 32 fixed to one end of the piezoelectric element 31, a base 33 as a stationary base for fixing the other end of the piezoelectric element 31, It comprises a locking member 34 slidably frictionally engaged with the body 32.

  The piezoelectric element 31 is a laminated piezoelectric element, and a lead wire 35 is soldered to its electrode. The lead wire 35 is connected to a piezoelectric actuator control device (not shown). As shown in FIG. 4, the piezoelectric element 31 is chamfered at four ridges in the longitudinal direction.

  The moving body 32 is provided so as to cover the piezoelectric element 31. The moving body 32 includes a sliding portion 36 that slides on the locking member 34 and a piezoelectric element fixing member 37 for fixing the piezoelectric element 31. The piezoelectric element fixing member 37 is made of an electrically insulating material, for example, ceramics, plastic, or the like. Further, a coupling member 38 is provided between the moving body 32 and the piezoelectric element 31. The coupling member 38 is preferably made of an elastic material, for example, a silicone adhesive. The coupling member 38 preferably has better thermal conductivity than air. Further, the coupling member 38 is also an electrical insulating material.

  The base (stationary base) 33 includes a piezoelectric element fixing section 39 for fixing one end of the piezoelectric element 31 and a supporting section 40 for slidably supporting the moving body 32. The sliding resistance between the moving body 32 and the supporting portion 40 supporting the moving body 32 is configured to be much smaller than the frictional force between the locking member 34 and the moving body 32. I have.

  On the other hand, the locking member 34 is provided with a guide hole 41 for guiding the moving body 32 through the moving body 32, and the moving body 32 moves by sliding the sliding portion 36 on the inner peripheral surface of the guide hole 41. The locking member 34 is provided with a spring, for example, a leaf spring 42, as urging means pressed against the moving body 32. The moving body 32 is pressed against the leaf spring 42 and the inner peripheral surface of the guide hole 41 of the locking member 34 by the leaf spring 42 to generate frictional resistance. The frictional resistance can be adjusted by the degree of fastening of the leaf spring 42.

  The locking member 34 is provided with an optical component such as a camera, a microscope, or an endoscope, such as a lens or a mirror, or an XY fine movement stage. For example, as a lens, a focus lens, a zoom lens, and the like are preferable.

(Action)
When a voltage for rapidly expanding the piezoelectric element 31 is applied from the piezoelectric actuator control device to the piezoelectric element 31 through the lead wire 35, the piezoelectric element 31 rapidly expands to the other end while one end is fixed to the base 33. When the inertial force generated at this time overcomes the frictional force between the locking member 34 and the moving body 32, the moving body 32 moves while leaving the locking member 34. Next, when the piezoelectric element 31 applies a voltage that contracts slowly, the inertial force generated at that time does not overcome the frictional force between the locking member 34 and the moving body 32, and the moving body 32 shrinks without moving relative to the locking member 34. By repeating these operations, the piezoelectric actuator 30 is driven.

(effect)
Since the coupling member 38 elastically supports the piezoelectric element 31 and the coupling member 38 fills the space between the moving body 32 and the piezoelectric element 31, an impact applied to the piezoelectric element 31 It is soft at 38, and the impact resistance is improved.
Since a material having high thermal conductivity is used for the coupling member 38, heat generated by the piezoelectric element 31 can be quickly radiated, and the performance of the piezoelectric element 31 does not deteriorate.

  Further, a piezoelectric element fixing member 37 and a coupling member 38 formed of an electrically insulating material electrically insulate the piezoelectric element 31 from the moving body 32, the locking member 34, and the base 33. Further, since the piezoelectric element 31 is covered with the electrically insulating connecting member 38, the electrical insulation between the piezoelectric element 31 and the moving body 32 is improved.

  Furthermore, since the ridge portion of the piezoelectric element 31 is chamfered, the ratio of the cross-sectional area of the piezoelectric element 31 to the cross-sectional shape area of the moving body 32 can be increased, so that the driving force generated by the piezoelectric element 31 is reduced. Therefore, the performance of the piezoelectric actuator 30 can be improved.

<Fourth embodiment>
The fourth embodiment of the present invention will be described with reference to FIG. FIG. 5 is a longitudinal sectional view of the piezoelectric actuator.

(Constitution)
The piezoelectric actuator 45 according to this embodiment includes a piezoelectric element 46, a coupling member 47 having one end connected to one end of the piezoelectric element 46, and a moving body 48 provided at the other end of the coupling member 47. The piezoelectric element 46 includes a base 49 as a stationary base for fixedly supporting the other end of the piezoelectric element 46 with an adhesive or the like, and a locking member 50 slidably and frictionally engaged with the moving body 48.

  The piezoelectric element 46 is a piezoelectric (electrostrictive) element. In this embodiment, a laminated piezoelectric element is used. Although a lead wire is fixed to the piezoelectric element 46, it is not shown in the present embodiment.

  The moving body 48 is slidably supported by being penetrated by the supporting portion 51 of the base 49. The sliding resistance between the moving body 48 and the support 51 is set to be much smaller than the frictional force between the locking member 50 and the moving body 48. A surface treatment or a sliding material is used for the sliding contact portion to reduce sliding resistance.

  The engagement member 52 is provided with a fitting hole 52 that penetrates the moving body 48, and the moving body 48 is fitted into the fitting hole 52 so as to slide. Further, an urging means such as a leaf spring in the above-described embodiment may be provided to press the moving body 48 against the locking member 50.

  Although not shown, the locking member 50 is fixed with an optical element such as a lens, a mirror, and a solid-state imaging device used for an endoscope, a microscope, a camera, and the like, but is not particularly limited. For example, an XY stage is fixed. Or it can be used as a positioning device.

  The coupling member 47 is configured by incorporating a displacement enlarging mechanism using elastic deformation. Although not shown, the displacement enlarging mechanism in this case enlarges the vibration of the piezoelectric element 46, that is, the amount of displacement, using the leverage principle. By using the principle of leverage, it is possible to arbitrarily set the relationship between the point of force, the fulcrum, and the point of action, thereby setting the displacement magnification rate arbitrarily. The portion of the displacement enlarging mechanism that is elastically deformed may be, for example, a fulcrum or the lever itself. Specifically, the lever may be configured by a leaf spring, or the lever and the fulcrum may be integrally formed, and the fulcrum portion may be elastically deformed to move the lever.

(Action)
The operation of the piezoelectric actuator 45 according to the fourth embodiment is the same as that of the third embodiment, and a description thereof will be omitted. The displacement enlarging mechanism increases the moving amount of the moving body 48.

(effect)
Since the piezoelectric element 46 and the moving body 48 are coupled by a displacement enlarging mechanism using elastic deformation, a large displacement can be obtained by a single expansion and contraction of the piezoelectric element 46, and Can be increased.

<Fifth embodiment>
The fifth embodiment of the present invention will be described with reference to FIG. FIG. 6 is a longitudinal sectional view of the piezoelectric actuator.

(Constitution)
The piezoelectric actuator 54 according to this embodiment includes a piezoelectric element 55, a moving body 56 provided at one end of the piezoelectric element 55, and a fixed member 57 as a stationary member slidably and frictionally engaged with the moving body 56. And a frictional force generating mechanism 58 for generating a frictional force between the moving body 56 and the fixed member 57.

  The piezoelectric element 55 is a piezoelectric (electrostrictive) element, and in this embodiment, a laminated piezoelectric element is used. A lead wire 59 for transmitting a drive signal to its electrode is soldered to the piezoelectric element 55. The lead wire 59 is connected to a piezoelectric actuator driving control device (not shown).

  The moving body 56 includes a piezoelectric element fixing member 61 attached to one end of a piezoelectric element 55, a sliding member 62 attached to the piezoelectric element fixing member 61 and sliding on an inner surface of the fixing member 57, It comprises a coupling member 63 attached to the other end of the element fixing member 61. The sliding member 62 has a cylindrical shape and is configured to cover the piezoelectric element 55. The moving body 56 has a structure in which a piezoelectric element fixing member 61 is attached to one end of the sliding member 62 and a coupling member 63 is attached to the other end of the sliding member 62 to make the inside airtight. The outer surface of the sliding member 62 that slides on the stationary member fixing member 57 is very smooth. The piezoelectric element fixing member 61 is formed of an electrical insulator. As the electric insulating material, for example, a hard ceramic or a hard plastic is preferable. Further, an insulating film may be applied to a metal material, for example, aluminum or the like before use.

  The coupling member 63 is for elastically coupling to the lead wire 59. For this purpose, the coupling member 63 may be a rear lid 64 attached to one end opening of the sliding member 62, or may be the rear lid 64. An adhesive 65 or the like that elastically connects the lead 64 and the lead wire 59 may be used, and at least one having a lower elastic modulus (softer) may be used as the connecting member 63. As the adhesive, a silicone adhesive or an epoxy adhesive having a small Young's modulus is preferable.

  The moving body 56 is provided with a shaft 66 through which the output of the piezoelectric actuator 54 can be taken out. For example, an optical element (not shown) of a driven body is fixed to the shaft 66. As the optical element, for example, there are a lens, a mirror, a solid-state imaging element, and the like used for an endoscope, a microscope, a camera, and the like.

  The inner surface of the fixing member 57 is cylindrical in shape so that it can slidably and frictionally engage with the moving body 56, and the sliding contact surface is very smooth. The outer shape of the fixing member 57 may be a shape required when the piezoelectric actuator 54 is incorporated.

The frictional force generating mechanism 58 is attached to the fixing member 57. As the frictional force generating mechanism 58, an urging member, for example, a leaf spring 67 is provided. One end of the leaf spring 67 is screwed and fixed to the fixing member 57 by a screw 68. This fixing method may be a method other than screwing, for example, using fusion or an adhesive. The fixing member 57 is formed with a slit or hole 69 into which the other end of the leaf spring 67 enters, and through this hole 69, comes into pressure contact with the outer surface of the sliding member 62 of the moving body 56 to frictionally engage. It has become. The slit or hole 69 and the leaf spring 67 are provided so that a frictional force can be generated even when the fitting length between the moving body 56 and the fixing member 57 is minimized.
Further, the frictional force generating mechanism 58 can adjust the frictional force by adjusting the biasing force of the leaf spring 67, for example.

(Action)
The operation will be described based on the above configuration. First, the frictional force generating mechanism 58 that generates a frictional force will be described. The free end of the leaf spring 67 presses against the outer surface of the sliding member 62 of the moving body 56, and presses the sliding member 62 of the moving body 56 against the fixed member 57 to obtain a frictional force therebetween. The frictional force between the sliding member 62 and the leaf spring 67 is obtained. The assembly can be performed by adjusting the frictional force.

  Next, the operation of the piezoelectric actuator 54 will be described. When a driving voltage at which the piezoelectric element 55 rapidly extends is applied to the piezoelectric element 55, if an inertial force generated in the moving body 56 at that time is larger than a frictional force between the moving body 56 and the fixed member 57 side. The moving body 56 moves minutely toward the shaft 66 side. Thereafter, if the piezoelectric element 55 is slowly contracted and a driving voltage is applied so that the generated inertial force is smaller than the frictional force, the moving body 56 stays in place and does not move. By repeating this cycle, the piezoelectric actuator 54 can be intermittently moved in the left direction in FIG. When the piezoelectric actuator 54 is driven in the reverse direction, a cycle of rapidly contracting the piezoelectric element 55 and extending it slowly may be repeated. The coupling member 63 elastically supports the lead wire 59.

(effect)
Since the frictional force is obtained by the leaf spring 67, the frictional force can be easily adjusted to an arbitrary value by adjusting the spring elastic force of the leaf spring 67. That is, it is possible to provide the piezoelectric actuator 54 in which the frictional force between the stationary member 57 as the stationary member and the moving body 56 can be easily adjusted.

  Since the moving body 56 has a cylindrical shape and is fitted with the fixing member 57, the center of the piezoelectric actuator 54 does not shift, and precise driving is possible.

  Since the sliding surfaces of the fixed member 57 and the moving body 56 are polished smoothly, the wear resistance is improved, and the quality of the piezoelectric actuator 54 is improved.

  Since the position of the leaf spring 67 and the like is determined so that the moving body 56 and the fixed member 57 can be fitted and frictionally engaged even if the shaft 66 extends to the maximum, there is no wasted space and stable. The frictional force can be provided, and the performance of the piezoelectric actuator 54 is stabilized.

  Since the piezoelectric element 55 is covered with the moving body 56, foreign matter does not adhere to the piezoelectric element 55, and the piezoelectric element 55 is not degraded or destroyed, which is reliable. In addition, since the piezoelectric element 55 is hermetically sealed, it is possible to prevent moisture, gas, and the like that deteriorate the piezoelectric element 55 from entering, and to improve resistance to moisture, gas, and the like. Further, there is no need to apply a moisture-proof coating or the like to the piezoelectric element 55 itself, and thus cost reduction can be achieved.

  Since the piezoelectric element fixing member 61 is made of the electrical insulator, the piezoelectric element 55 is electrically insulated, and the electrical safety is improved. Since the piezoelectric element 55 is covered with the electrical insulator, design and manufacture can be facilitated and cost reduction can be achieved, for example, the restriction on the mounting height of the lead wire 59 is relaxed.

  Since the lead wire 59 is supported by the coupling member 63, stress concentration at the time of expansion and contraction of the lead wire 59 due to advance and retreat of the piezoelectric actuator 54 can be dispersed, and durability against repeated driving of the piezoelectric actuator 54 can be improved. Is improved.

<Sixth embodiment>
A sixth embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a longitudinal sectional view of the piezoelectric actuator, and FIG. 8 is a longitudinal sectional view of the vicinity of a frictional force generating mechanism of the piezoelectric actuator.

(Constitution)
The piezoelectric actuator 70 according to this embodiment includes a piezoelectric element 71, a moving body 72 provided at one end of the piezoelectric element 71, and a fixed member as a stationary member slidably and frictionally engaged with the moving body 72. 73, and a frictional force generating mechanism 74 for generating a frictional force between the moving body 72 and the fixed member 73.

  The piezoelectric element 71 is a piezoelectric (electrostrictive) element, and in this embodiment, a laminated piezoelectric element is used. A lead wire 75 is soldered to the end of the piezoelectric element 71 closer to the moving body fixed side. The means for connecting the lead wires 75 is not limited to soldering, but may be fixed using a conductive adhesive. The lead wire 75 is connected to a piezoelectric actuator control device (not shown).

  The moving body 72 is provided so as to cover the piezoelectric element 71, and the piezoelectric element 71 is installed inside the sealed moving body 72. The moving body 72 is slidably installed in a guide hole 76 of a fixed member 73 as a stationary member. The moving body 72 includes a cylindrical sliding member 77, a front cover 78 adhesively fixed to a front end of the sliding member 77, and a piezoelectric element fixing member 79 adhesively fixed to a rear end of the sliding member 77. It is composed of The surface of the sliding member 77 is made very smooth so that it can slide smoothly into the guide hole 76 of the fixing member 73.

  The shaft 80 protrudes from a front cover 78 of the sliding member 77. The material of the front cover 78 and the shaft 80 is preferably a light material such as aluminum or plastic. The optical element (not shown) and the fine movement table (not shown) as described in the fifth embodiment are connected to the shaft 80.

  The piezoelectric element fixing member 79 attached to the other end of the sliding member 77 has a hole 81 through which the lead wire 75 passes. The lead wire 75 and the hole 81 are elastically fixed via a connecting member 82. The coupling member 82 may be an elastic body such as a silicone or rubber filler or an adhesive. An epoxy adhesive having a low Young's modulus may be used.

  The piezoelectric element fixing member 79 is made of an electrical insulator. For example, plastic, ceramic, or the like, or metal whose surface is insulated is preferable.

  A tubular electrical insulator 84 is provided between the inner surface of the sliding member 77 and the outer periphery of the piezoelectric element 71. In the present embodiment, a tube made of polyimide is used for the electrical insulator 84. The tubular electrical insulator 84 does not have to be fixedly adhered to the moving body 72.

  The inner surface of the guide hole 76 of the fixing member 73 is configured so that the sliding member 77 of the moving body 72 can slide smoothly, and the inner surface for sliding is very smooth. The external shape of the fixing member 73 may be any shape suitable for incorporating the piezoelectric actuator 70 into a camera, a microscope, or an endoscope as described in the fifth embodiment.

  Further, the frictional force generating mechanism 74 is provided on a wall of the fixing member 73. The frictional force generating mechanism 74 adjusts a pressing member 85 pressed against the outer peripheral surface of the sliding member 77 of the moving body 72, a spring 86 for pressing the pressing member 85 in a pressing direction, and a pressing force of the spring 86. The adjusting screw 87 is provided. The adjusting screw 87 is screwed into the wall of the fixing member 73, and constitutes a frictional force adjusting means for adjusting the frictional force between the fixing member 73 and the moving body 72 according to the amount of screwing of the adjusting screw 87. . The distal end of the pressing member 85 is a sliding surface 88 that is smoothly formed so as to slide smoothly on the outer peripheral surface of the sliding member 77.

  The biasing spring 86 may be an elastic body, and for example, a rubber member 89 may be used instead of the spring 86 as shown in FIG. FIG. 8 shows only the frictional force generating mechanism in this case.

(Action)
The operation will be described based on the above configuration. First, a method of generating a frictional force by the frictional force generating mechanism 74 will be described. When the adjusting screw 87 is turned and the adjusting screw 87 is screwed into the fixing member 73 to press the spring 86, the pressing force acts on the pressing member 85 and the outer peripheral surface of the sliding member 77 of the moving body 72. Press As a result, a vertical drag is generated, and a frictional force is generated between the moving body 72 and the moving body 72. Further, by selecting the screwing amount of the adjusting screw 87, the frictional force is changed and adjusted to a predetermined frictional force.

  The driving operation of the piezoelectric actuator 70 is the same as that of the above-described fifth embodiment, and a description thereof will be omitted. However, since the fixing position of the piezoelectric element 71 is different, the traveling direction in FIG. 7 is opposite to that in the above-described fifth embodiment.

(effect)
By selecting the screwing amount of the adjusting screw 87, the frictional force between the moving body 72 and the fixed member 73 can be easily adjusted to a constant value, so that the performance of the piezoelectric actuator 70 is stabilized. That is, it is possible to provide a piezoelectric actuator that can easily adjust the frictional force.

  Since the piezoelectric element 71 is covered with the moving body 72 and sealed inside the moving body 72, the performance of the piezoelectric element 71 is not deteriorated by humidity, and the piezoelectric element 71 is not affected by an external environment such as liquid or gas. Stable performance can be maintained.

  Since the lead wire 75 is soldered near the piezoelectric element fixing member 79, the piezoelectric element 71 is inclined and adhered due to variation in adhesion between the piezoelectric element 71 and the piezoelectric element fixing member 79. Also, the possibility that the soldered portion of the lead wire 75 comes into contact with the sliding member 77 of the moving body 72 is reduced, and the electrical safety is improved.

  Since the lead wire 75 is elastically fixed to the piezoelectric element fixing member 79 via the coupling member 82, stress concentrates on the fixing portion of the lead wire 75 when the piezoelectric actuator 70 advances and retreats. Therefore, the resistance of the lead wire 75 to the stretching force can be improved.

  Since the tubular electrical insulator 84 is provided between the piezoelectric element 71 and the moving body 72, the tolerance of the electrode height of the piezoelectric element 71 and the height of the soldering portion of the lead wire 75 are set. Even if there is such a variation, the electrodes and the lead wires 75 do not contact the moving body 72. As a result, the dimensional tolerance of the piezoelectric element 71 and the restriction on the mounting height of the lead wire 75 can be relaxed, so that the piezoelectric actuator 70 can be manufactured at low cost. Further, electrical safety is improved.

<Seventh embodiment>
The seventh embodiment of the present invention will be described with reference to FIG. FIG. 9 is a longitudinal sectional view of the vicinity of the frictional force generating mechanism of the piezoelectric actuator.

(Constitution)
The seventh embodiment is an example in which the frictional force generating mechanism in the above-described sixth embodiment is modified. Only the deformed frictional force generating mechanism 74 will be described, and the other parts will not be described because they are the same as in the above-described sixth embodiment.

  The frictional force generating mechanism 74 includes a pressing member 85 pressed against the outer peripheral surface of the sliding member 77 of the moving body 72, and a balloon 92 for urging the pressing member 85 in the pressing direction. These members are disposed in a hole 93 formed in the wall of the fixing member 73. The contact surface of the pressing member 85 is configured to be smoothly slidable with the sliding member 77.

  The balloon 92 is provided with an inlet 94 for liquid or gas, and a syringe or the like is inserted into the inlet 94 to fill the inside of the balloon 92 with liquid or gas so that the balloon 92 can be inflated. It has become. The fixing member 73 is provided with an injection hole 95 used for inserting an injection device when injecting a liquid or gas into the injection port 94 of the balloon 92.

(Action)
The operation of the frictional force generating mechanism 74 will be described. By injecting a liquid or a gas into the balloon 92, the balloon 92 expands, and the pressing member 85 is pushed toward the sliding member 77 of the moving body 72. As a result, the pressing member 85 presses against the sliding member 77 of the moving body 72 and presses the sliding member 77 against the inner surface of the guide hole 76 of the fixed member 73. Then, these pressing forces become normal drag and generate frictional force.

  The driving operation of the piezoelectric actuator 70 is the same as that of the above-described sixth embodiment, and the description thereof is omitted.

(effect)
In this embodiment, the balloon 92 is used as the urging means in the frictional force generating mechanism 74, and the pressure of gas or liquid in the balloon 92 can be easily changed, and the frictional force can be easily adjusted. That is, a frictional force adjusting mechanism is configured.

  The effects other than the frictional force generating mechanism 74 are the same as in the above-described sixth embodiment, and will not be described.

<Eighth embodiment>
An eighth embodiment of the present invention will be described with reference to FIG. FIG. 10 is a longitudinal sectional view of the vicinity of the frictional force generating mechanism of the piezoelectric actuator.

(Constitution)
This embodiment is also a modification of the above-described sixth embodiment, and differs from the sixth embodiment only in the configuration of the frictional force generating mechanism 74. The description of the other components is omitted.

  The frictional force generating mechanism 74 includes a pressing member 85, a second piezoelectric element 96, and a fixing plate 97 in a hole 93 formed in a wall of the fixing member 73. The piezoelectric element 96 is interposed between the pressing member 85 and the fixing plate 97. The pressing member 85 may be adhesively fixed to the tip of the second piezoelectric element 96, or may be in elastic contact with the pressing member 85. Further, the other end of the second piezoelectric element 96 and the fixing plate 97 may be bonded and fixed, or may be in elastic contact with each other.

  The fixing plate 97 is adhesively fixed to the fixing member 73. The fixing plate 97 is a holding member that receives the second piezoelectric element 96. As the holding member, a screw member may be used instead of the fixing plate 97, and the fixing member 97 may be screwed into the fixing member 73 and fixed. Further, a preload may be applied to the pressing member 85 and the second piezoelectric element 96 by screwing.

  A lead wire 98 is soldered to the second piezoelectric element 96, and the lead wire 98 is guided to the outside of the fixing member 97 through a hole 99 of the fixing plate 97.

(Action)
The operation of only the frictional force generating mechanism 74 will be described, and other operations will not be described because they are the same as in the sixth embodiment.

  When a voltage is applied to the second piezoelectric element 96, the second piezoelectric element 96 expands and presses the pressing member 85. The pressing force differs depending on the applied voltage. Thereby, the sliding member 77 of the moving body 72 is pressed against the fixed member 73. Then, the moving body 72 and the fixed member 73 are frictionally engaged.

(effect)
Since the pressing force of the pressing member 85 can be easily changed by the voltage applied to the second piezoelectric element 96, the adjustment of the frictional force becomes easy. Since the frictional force can be electrically controlled, complicated control of the piezoelectric actuator 70 is possible. That is, a frictional force adjusting mechanism is configured.

  When a screw is used instead of the fixing plate 97, the pressing member 85 can be pressed before applying a voltage to the second piezoelectric element 96 to apply a preload, so that a voltage is applied to the piezoelectric element 96. Then, it becomes easier to adjust to the desired frictional force.

  Other effects are the same as those of the above-described sixth embodiment, and a description thereof will not be repeated.

<Ninth embodiment>
A ninth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a longitudinal sectional view of the vicinity of the frictional force generating mechanism of the piezoelectric actuator.

(Constitution)
This embodiment is a modification of the frictional force generating mechanism 74 shown in the eighth embodiment. The description of the other components is omitted. In the frictional force generating mechanism 74 of the present embodiment, the second piezoelectric element 96 of the above-described frictional force generating mechanism 74 is replaced with a chemo mechanism 101. Chemomechanism 101 functions in substantially the same way as a piezoelectric element.

(Action)
When a voltage is applied to the chemo mechanism 101, the chemo mechanism 101 extends, presses the pressing member 85, and presses the sliding member 77 of the moving body 72 to the fixed member 73 via the pressing member 85. Thereby, the moving body 72 and the fixed member 73 are frictionally engaged. The other operations are the same as those of the above-described eighth embodiment, and the description is omitted.

(effect)
The effects of the present embodiment are the same as those of the eighth embodiment, and a description thereof will be omitted.

<Tenth embodiment>
The tenth embodiment of the present invention will be described with reference to FIG. FIG. 12 is a longitudinal sectional view of the vicinity of the frictional force generating mechanism of the piezoelectric actuator.

(Constitution)
This embodiment is also a modification of the above-described eighth embodiment, and differs from the eighth embodiment only in the configuration of the frictional force generating mechanism 74. Therefore, the description of the other components is omitted.

  The frictional force generating mechanism 74 according to the present embodiment includes a pressing member 85, a coil 102, and an ultra-pressurizing member for pressing and pressing the pressing member 85 into a hole 93 formed in the wall of the fixing member 73. The magnetostrictive element 103 is provided with a fixture 104 for receiving a rear end of the giant magnetostrictive element 103. The giant magnetostrictive element 103 is coaxially arranged in the winding core of the coil 102. The giant magnetostrictive element 103 is an element having a property of extending when a magnetic field is applied, and has a property functionally similar to that of a piezoelectric element.

  The pressing member 85 is elastically fixed to the tip of the giant magnetostrictive element 103, and the fixture 104 is fixed to the other end of the giant magnetostrictive element 103. The fixing tool 104 is adhesively fixed to the fixing member 73. The coil 102 provided around the giant magnetostrictive element 103 is bonded and fixed to the inner wall of the hole 93 of the fixing member 73. A lead wire 105 is connected to the coil 102. The lead wire 105 passes through the fixture 104 and is led out.

  Before applying a voltage to the coil 102, the giant magnetostrictive element 103 and the pressing member 85 are pressed against the sliding portion 77 of the moving body 72 using the fixing tool 104, so that a preload is applied to the giant magnetostrictive element 103. May be given.

(Action)
The operation of the frictional force generating mechanism 74 will be described. When a voltage is applied to the coil 102, a magnetic field is generated. Then, the giant magnetostrictive element 103 extends, and at this time, the pressing member 85 fixed to the giant magnetostrictive element 103 is pressed. Then, the pressing member 85 presses the moving body 72 against the fixed member 73, and the moving body 72 and the fixed member 73 are frictionally engaged. The operation of the piezoelectric actuator 70 is the same as that of the above-described eighth embodiment, and a description thereof will be omitted.

(effect)
The magnitude of the frictional force with which the moving body 72 and the fixed member 73 are frictionally engaged can be easily adjusted by the value of the voltage applied to the coil 102.

  When a preload is applied to the giant magnetostrictive element 103, the frictional force generated by the frictional engagement can be adjusted with a certain width, so that it is easy to adjust to the target frictional force. The other effects of the piezoelectric actuator 70 are the same as those of the above-described eighth embodiment, and will not be described.

<Eleventh embodiment>
An eleventh embodiment of the present invention will be described with reference to FIG. FIG. 13 is a longitudinal sectional view of the vicinity of the frictional force generating mechanism of the piezoelectric actuator.

(Constitution)
This embodiment is also a modification of the above-described eighth embodiment, and differs from the eighth embodiment only in the configuration of the frictional force generating mechanism 74. Therefore, the description of the other components is omitted.

  The frictional force generating mechanism 74 in this embodiment is configured by disposing a pressing member 85, a solenoid 108, and a fixing tool 109 similar to the above in a hole 93 formed in a wall of the fixing member 73. The solenoid 108 includes a coil 110 and a shaft (plunger) 111. The coil 110 is adhesively fixed to the fixture 109, and the shaft 111 is adhesively fixed to the pressing member 85. The shaft 111 is formed of a magnetic material such as a magnet so as to have magnetism. The fixing tool 109 is bonded and fixed to the fixing member 73 of the piezoelectric actuator 70. The coil 110 is adhesively fixed to the inner wall of the hole 93 of the fixing member 109. A lead wire 112 is connected to the coil 110. The lead wire 112 passes through the fixture 109 and is led out.

(Action)
The function of the frictional force generating mechanism 74 will be described. When a voltage is applied to the coil 110, the shaft 111 is urged to be pushed out of the coil 110 by repelling a magnetic field generated in the coil 110. . Then, the pressing member 85 fixed to the shaft 111 presses the sliding member 77 of the moving body 72 against the fixed member 73, so that the moving body 72 and the fixed member 73 are slidably frictionally engaged. By changing the voltage applied to the coil 110, the force pressing the pressing member 85 changes. That is, it constitutes a frictional force adjusting mechanism for adjusting the frictional force. The operation of the piezoelectric actuator 70 is the same as that of the above-described eighth embodiment, and the description is omitted.

(effect)
The other effects of the piezoelectric actuator 70 are the same as those of the above-described eighth embodiment, and will not be described.

  Since the solenoid 108 is used for the frictional force generating mechanism 74, the force for pressing the pressing member 85 can be adjusted by changing the voltage applied to the coil 110, and the frictional force can be easily set to a desired value.

<Twelfth embodiment>
A twelfth embodiment of the present invention will be described with reference to FIG. FIG. 14A is a vertical cross-sectional view of the vicinity of a frictional force generating mechanism of the piezoelectric actuator, and FIG. 14B is a cross-sectional view taken along line AA in FIG.

(Constitution)
The piezoelectric actuator according to the present embodiment includes a piezoelectric element 113, a moving body 114 fixed to one end of the piezoelectric element 113, a fixed member 115 as a stationary member slidably frictionally engaged with the moving body 114. It is configured with.
As the piezoelectric element 113, a laminated piezoelectric element is used, but another electrostrictive element may be used.

  A lead wire 116 is connected to the piezoelectric element 113 by soldering. As shown in FIG. 14B, the piezoelectric element 113 is chamfered at four ridges in the longitudinal direction.

  The moving body 114 includes a piezoelectric element fixing member 117, a cylindrical sliding member 118 having one end connected and fixed to the piezoelectric element fixing member 117, and a rear lid 119 attached to the other end of the sliding member 118 by bonding. It is configured. One end of the piezoelectric element 113 is bonded and fixed to the piezoelectric element fixing member 117. The piezoelectric element 113 is hermetically disposed inside the moving body 114 and is surrounded by the moving body 114. The rear lid 119 is provided with a hole 119a through which the lead wire 116 passes, and the lead wire 116 is bonded and fixed in the hole 119a. The hole 119a is filled with an adhesive and closed.

  As shown in FIG. 14A, a coupling member 120 is provided between the moving body 114 and the piezoelectric element 113. The coupling member 120 is attached to the inner surface of the cylindrical sliding member 118 of the moving body 114, and is interposed between the moving body 114 and the piezoelectric element 113 to elastically couple them. In the present embodiment, in particular, the coupling member 120 is provided between the movable body 114 and the free end of the piezoelectric element 113 serving as the lead wire connection end.

  The outer surface of the sliding member 118 is formed so as to be slidable with the fixing member 115. The sliding surface of the fixing member 115 is also configured smoothly.

  The fixing member 115 is provided with a frictional force generating mechanism 121. The frictional force generating mechanism 121 includes at least one slit 122 provided at an end of the fixing member 115, a screw portion 123 provided at an end having the slit 122, and a nut 124 coupled to the screw portion 123. I do. The screw portion 123 is formed as a tapered screw portion. This configuration also serves as a frictional force adjusting mechanism that can adjust the frictional force according to the amount of tightening of the nut 124.

(Action)
The frictional force generating mechanism 121 will be described. When the nut 124 is tightened into the screw portion 123, a slit 122 is provided in the screw portion 123, and since the screw portion 123 is tapered, the inner diameter of the fixing member 115 becomes smaller, The moving body 114 is tightened. Then, the fixed member 115 and the moving body 114 are slidably frictionally engaged with each other. Since this frictional force changes according to the amount of tightening of the nut 124, the frictional force can be appropriately adjusted.

  The coupling member 120 is held by the moving body 114 and elastically supports a part of the piezoelectric element 113.

  Other operations of this piezoelectric actuator are the same as those described in the above-described eighth embodiment, and thus description thereof is omitted.

(effect)
The frictional force generating mechanism 121 can easily adjust the frictional force according to the degree of tightening of the nut 124, and can stabilize the performance of the piezoelectric actuator. Since the coupling member 120 is provided to elastically support the piezoelectric element 113, the piezoelectric element 113 does not lose its generated force and has a structure that is strong against impact, and the impact resistance of the piezoelectric actuator is improved. .

  Furthermore, since the ridge of the piezoelectric element 113 is chamfered, the ratio of the cross-sectional area of the piezoelectric element 113 to the cross section of the moving body 114 can be increased, so that the force generated by the piezoelectric element 113 can be increased, The performance of the actuator can be improved.

  The other effects of the piezoelectric actuator are the same as those described in the ninth embodiment, and a description thereof will be omitted.

<Thirteenth embodiment>
A thirteenth embodiment of the present invention will be described with reference to FIGS.

(Constitution)
In the present embodiment, as shown in FIG. 15, the above-described piezoelectric actuator is used as a driving unit of the focus adjustment mechanism 204 of the observation optical system incorporated in the distal end portion 203 of the insertion section 202 of the endoscope 201. Things.

  In the observation optical system of the endoscope 201, an observation window 205 is provided on the distal end surface of the distal end component 203. An observation optical system is mounted in the internal space of the distal end configuration portion 203, and the focus adjustment mechanism 204 is installed at a side portion of the mounting position.

  The observation optical system includes a front fixed lens 206 facing the observation window 205, a rear fixed lens 208 spaced apart from the front fixed lens 206, and a fixed lens 206. A focus adjustment lens 209 is provided between the lens unit and the rear-side fixed lens 208 and is movable along the optical axis direction of the observation optical system. These lenses 206, 208, and 209 constitute an objective lens group of the observation optical system.

  A lens frame 210 of a focus adjusting lens 209 is supported on a lens barrel 207 holding the front and rear fixed lenses 206 and 208 so as to be movable along the optical axis direction of the observation optical system. A rack gear 211 is provided on the lower surface of the lens frame 210, and the rack gear 211 meshes with a pinion gear 212 rotated by a piezoelectric actuator described later.

  Further, an actuator unit 213 having a piezoelectric actuator as described later is mounted in the distal end portion 203. The actuator unit 213 is provided with a rack gear 214 that meshes with the pinion gear 212. The pinion gear 212 meshes with the rack gear 211 of the lens frame 210, and moves the lens frame 210 of the focus adjustment lens 209 in the optical axis direction of the observation optical system.

  Behind the rear fixed lens 208, a solid-state image sensor 215 such as a CCD for converting an observation image formed by the objective lens group of the observation optical system into an electric signal is provided.

  The actuator unit 213 is configured as shown in FIG. That is, a cylindrical circular pipe 216 as a stationary member fixedly attached to the member of the distal end component 203, a moving body 217 slidably provided in the circular pipe 216, and one end of the moving body 217. And a piezoelectric element (electrostrictive element) 218 as an impact force generating section for applying an impact to the moving body 217 by applying an electric voltage.

  Here, for the piezoelectric element (electrostrictive element) 218, for example, an electrode is formed on ceramics such as barium titanate, zirconate titanate, and porcelain, and mechanical expansion deformation is performed by applying a direct current to the electrode. Is what happens. The piezoelectric element 218 is an element in which a distortion proportional to the electric field intensity is generated due to a reverse voltage effect, and the electrostrictive element is an element in which a distortion proportional to the square of the electric field intensity is generated when a driving voltage is applied. , Both are called piezoelectric elements.

  The moving body 217 has a piezoelectric element fixing member 221 for fixing one end of a piezoelectric element 218, a circular tube part 222 having one end fixed to the piezoelectric element fixing member 221 and covering the piezoelectric element 218, and a circular tube part 222. And a lid part 223 attached to the other end of the head. A lead wire 224 is connected to the piezoelectric element 218, and the lead wire 224 passes through the center of the lid 223 in an airtight manner and is led out. The moving body 217 hermetically contains the piezoelectric element 218.

  One end of a leaf spring 225 is attached to the circular tube 216 with a screw 226, and the free end of the leaf spring 225 passes through an opening 227 formed in the circular tube 216 and the circular tube portion 222 of the moving body 217. It is pressed against the outer circumference. This pressing load generates a frictional force between the circular tube 216 and the leaf spring 225 having a strength corresponding thereto. Further, the pressing load can be adjusted by adjusting the tightening and tightening of the screw 226, and constitutes a frictional force adjusting mechanism.

  A shaft 228 protrudes from the piezoelectric element fixing member 221 of the movable body 217, and a rack gear 214 that meshes with the pinion gear 212 is formed on the shaft 228. That is, power transmission between the lens frame 210 of the observation optical system and the moving body 217 is performed via the gear system. For this reason, compared with the conventional coupling using a connecting member, a moment generated in proportion to the distance between the moving body 217 and the lens frame 210 does not act, and therefore, at the time of each movement, twisting occurs. Less likely to occur.

  The lead wire 224 connected to the piezoelectric element 218 is disposed over the insertion section 202 of the endoscope 201, the operation section 231 shown in FIG. 17, and the universal cord 232, and is connected to the external control section 233. Has become. Here, the lead wire 224 attached to the piezoelectric element 218 is fixed to the piezoelectric element 218 at the following two points as shown in FIG. That is, one point is soldered to the electrode portion 218a of the piezoelectric element 218, and the other point is fixed to the dummy part 218b of the piezoelectric element 218 by an adhesive. The piezoelectric element 218 includes a vertically stacked, a horizontally stacked and a single layer.

  The inner surface of the circular tube 216 and the outer surface of the circular tube portion 222 are subjected to a surface treatment for improving abrasion resistance, for example, alumite oxalate and titanium coating. Further, the surface of the piezoelectric element 218 is provided with a parylene coat for improving heat and humidity resistance and chemical resistance.

  In addition, the control unit 233 outputs, for example, each voltage having each drive waveform of the first drive waveform of the piezoelectric element 218 shown in FIG. 19A and the second drive waveform of the piezoelectric element 218 shown in FIG. A voltage applying means for generating and applying the voltage to the piezoelectric element 218 as necessary is provided. Here, the first drive waveform includes a region a where the applied voltage is gradually reduced from the set voltage to the 0 potential within a predetermined set time T of one pulse, and a sharp increase from the 0 potential to the predetermined set voltage. b region is provided. Further, the second drive waveform includes a region c in which the applied voltage is gradually increased from 0 potential to a predetermined set voltage within a predetermined set time T of one pulse, and d in which the applied voltage is rapidly decreased from the set voltage to 0 potential. Region is provided.

(Action)
Next, the operation of the above configuration will be described. First, the operation of the actuator unit 213 driven by the first drive waveform in FIG. 19A will be described with reference to FIG. When the actuator unit 213 is stopped, the circular tube portion 222 is pressed against the inner surface of the circular tube 216 by the leaf spring 225 and held in a state of being frictionally engaged with an appropriate frictional force.

  When a voltage having a first drive waveform is applied to the piezoelectric element 218 of the actuator unit 213, the piezoelectric element 218 contracts slowly in the region a of the first drive waveform and rapidly expands in the region b. return. In other words, when the piezoelectric element 218 contracts slowly in the region a of the first drive waveform, the moving body 217 causes the friction of the contact surface with the leaf spring 225 and the inner surface of the circular tube 216 as shown in FIG. It is held stationary by force.

  Further, when the piezoelectric element 218 expands abruptly in the region b of the first drive waveform, the impact force pressing the moving body 217 leftward in FIG. appear. Therefore, the moving body 217 has a center of gravity determined by the own weight of the piezoelectric element 218 and the mass of the moving body 217 due to the impact force from the piezoelectric element 218 as a fixed point and moves leftward in the drawing as shown in FIG. Moving.

  When the actuator unit 213 is driven by the second drive waveform in FIG. 19B, the actuator unit 213 operates as shown in FIG.

  Here, when a voltage having the second drive waveform is applied to the piezoelectric element 218 of the actuator unit 213, the piezoelectric element 218 expands slowly in the region c of the second drive waveform, and abruptly contracts in the region d. Repeat. In other words, when the piezoelectric element 218 is slowly extended in the region c of the second drive waveform, the moving body 217 has friction between the leaf spring 225 and the inner surface of the circular tube 216 as shown in FIG. It is held stationary by force.

  Further, when the piezoelectric element 218 contracts rapidly in the d region of the second drive waveform, the impact force pulling the moving body 217 rightward in FIG. 20B by the sudden contraction of the piezoelectric element 218. appear. Therefore, the moving body 217 has the center of gravity determined by the own weight of the piezoelectric element 218 and the mass of the moving body 217 due to the impact force from the piezoelectric element 218 as a fixed point, and moves rightward in the drawing as shown in FIG. Moving.

  Therefore, when the first driving waveform is applied to the piezoelectric element 218 during the operation of the actuator unit 213, the moving body 217 moves forward in the left direction in FIG. 1 and the second driving waveform is applied to the piezoelectric element 218. In this case, the moving body 217 retreats leftward in FIG. As a result, the lens 210 of the focus adjustment lens 209 also moves back and forth in conjunction with the operation of the moving body 217, so that the position of the focus adjustment lens 209 is moved in the front and rear direction, and the focal position of the objective lens group of the observation optical system Can be adjusted.

  Therefore, in the above-described configuration, the moving body 217 connected to the rack gear 211 of the lens frame 210 via the pinion gear 212, and is fixed to the moving body 217, and expands and contracts by applying a voltage. Since the actuator unit 213 is composed of only the piezoelectric element 218 that applies an impact force to the moving body 217 by the expansion and contraction operation, the plate spring 225, and the circular tube 216, the inertial body can be omitted. Therefore, the number of components can be reduced as compared with a general piezoelectric actuator, the cost of assembly can be reduced, and the entire actuator unit 213 can be downsized.

  Furthermore, since the actuator unit 213 having the above configuration is used as an actuator of the focus adjustment mechanism 204 of the observation optical system of the endoscope 201, the rigid portion formed by the distal end configuration portion 203 of the insertion portion 202 of the endoscope 201 is used. Can be reduced, and the burden on the patient when inserting the insertion section 202 of the endoscope 201 can be reduced.

<Fourteenth embodiment>
A fourteenth embodiment of the present invention will be described with reference to FIG. FIG. 21 is a longitudinal sectional view of the piezoelectric actuator of the focus adjusting mechanism in the observation optical system of the endoscope.

(Constitution)
This embodiment is a modification of the actuator unit according to the thirteenth embodiment. In this actuator unit 213, a frictional force generating means for generating a frictional force between a circular tube 216 as a stationary member and a moving body 217 uses a magnetic fluid 241 instead of the leaf spring 225. That is, the groove 242 is provided in a part of the inner surface of the circular tube 216, and the magnetic fluid 241 is sealed in the space between the circular tube portion 222 and the groove 242 of the moving body 217. Here, the circular tube portion 222 of the moving body 217 is made of a magnetic material, and the magnetic fluid 241 does not flow out because it is attracted to the groove 242 by its magnetic force. Further, the magnetic fluid 241 generates a frictional force between the magnetic fluid 241 and the circular tube portion 222 when the moving body 217 moves with respect to the circular tube portion 222. Further, the adjustment of the frictional force can be changed by changing the contact state. For example, increasing or decreasing the amount of the magnetic fluid 241 also increases or decreases the frictional force. Also, the frictional force can be changed by changing the magnetic force of the groove 242. That is, this constitutes a frictional force adjusting mechanism.

<Fifteenth embodiment>
A fifteenth embodiment of the present invention will be described with reference to FIG. FIG. 22A is a longitudinal sectional view of a focus adjusting mechanism and an actuator thereof in an observation optical system of an endoscope, and FIG. 22B is a front view of a part thereof.

(Constitution)
This embodiment is also a modification of the above-described thirteenth embodiment. That is, the link 251 is used instead of the gear means for coupling the moving body 217 in the actuator unit 213 and the lens frame 210 of the focus adjustment mechanism. A pin 252 is provided on the lens frame 210, and a pin 253 is provided on the shaft 228 of the moving body 217. The link 251 is rotatably supported by a pin 255 attached to a fixed member in the distal end component, and the retaining ring 256 prevents the link 251 from coming off in the axial direction of the pin 255. The link 251 has U-shaped notches 257, 258 formed at both ends thereof, and the pins 252, 253 are fitted into and engaged with the notches 257, 258, respectively.

(Action)
When the actuator unit 213 operates, the moving body 217 moves and moves the lens frame 210 via the link 251. Since the transmission of power between the lens frame 210 and the moving body 217 is performed via the link 251, a moment generated in proportion to the distance between the lens frame 210 and the moving body 217 does not act. Less likely to be twisted when moving.

<Sixteenth embodiment>
A sixteenth embodiment of the present invention will be described with reference to FIG. FIG. 23 is a longitudinal sectional view of a focus adjusting mechanism and its actuator in the observation optical system.
This embodiment is also a modification of the above-described thirteenth embodiment, in which the shaft 228 of the moving body 217 is movably fitted in the hole 261 of the fixing member 260 in the distal end portion 203 of the endoscope. The leaf spring 262 is directly attached to the fixed member 260 as a stationary member, and a frictional force is generated between the leaf spring 262 and the shaft 228.

  One end of the leaf spring 262 is fixed to a fixing member 260 of the endoscope distal end portion by a fixing screw 263, and the other end is attached to the fixing member 260 by an adjusting screw 264 so as to be able to be pushed into the fixing member 260. The central part of the leaf spring 262 is in contact with the shaft 228 of the moving body 217 so as to press it. The moving body 217 generates a frictional force between the leaf spring 262 and the inner surface of the circular tube 216. Further, the pressing load on the shaft 228 is adjusted by the degree of tightening of the adjusting screw 264, and a mechanism for adjusting the frictional force is configured.

<Seventeenth embodiment>
A seventeenth embodiment of the present invention will be described with reference to FIGS. FIG. 24 is a longitudinal sectional view of an actuator part, FIG. 25 (a) is a longitudinal sectional view showing a state where the inner surface of the circular tube and the tip of the leg of the moving body are in contact with each other, and FIG. FIG. 4 is a front view of a state in which the tip of the leg of the moving body is in contact with the moving body.

  This embodiment is also a modification of the above-described thirteenth embodiment. The moving body 217 in the actuator unit 213 includes a shaft 271, a frictional force adjusting nut 272, and a leaf spring 273. The leaf spring 273 has two legs 274, and the tip 275 of each leg 274 is in contact with the inner surface of the circular tube 216. A pressing load is applied between the inner surface of the circular tube 216 and the tip 275 of the leg 274 by the leaf spring 273.

  The adjusting nut 272 is screwed and fixed to a male screw portion 276 formed at the base of the shaft 271. By rotating the adjusting nut 272, a frictional force generating mechanism for applying a tightening force to the fixing portion of the leaf spring 273 is configured. I do. Further, the configuration also serves as a mechanism for adjusting the pressing load by changing the opening angle of the leg 274 of the leaf spring 273.

  FIG. 25 shows a state in which the inner surface of the circular tube 216 is in contact with the tip 275 of the leg 274. As shown in FIG. 25, the distal end 275 of the leg 274 has an R in any of a cross section parallel to and perpendicular to the axis of the circular tube 216. R of the parallel section is smaller than r of the inner surface of the circular tube 216. Therefore, the tip portion is in point contact with the circular tube 216. Therefore, even if the axial center of the moving body 217 is slightly displaced from the axial center of the circular tube 216, the contact area is hardly changed due to the point contact, and as a result, the frictional force is hardly changed.

[Appendix]
1. A moving body, a piezoelectric vibrator fixed to the moving body, a stationary fixing member frictionally engaged with the moving body, abrupt deformation of the piezoelectric vibrator, and an impact on the moving body by the piezoelectric vibrator; Driving means for moving the movable body with respect to the stationary fixed member by overcoming frictional engagement between the movable body and the stationary fixed member. A piezoelectric actuator comprising a frictional force adjusting means for adjusting a frictional force.

1-1. 2. The piezoelectric actuator according to claim 1, wherein the moving body has at least two legs, and the frictional force adjusting means includes an adjusting member for limiting deflection of the legs.
1-2. 3. The piezoelectric actuator according to claim 1, wherein the adjustment member also serves as a centering mechanism for maintaining a posture of the piezoelectric actuator.

1-3. The piezoelectric actuator according to additional item 1-1, wherein an electrical insulating material is provided between the leg and the piezoelectric element.
1-4. The piezoelectric actuator according to Additional Items 1-3, wherein the insulator is made of ceramic.
1-5. 3. The piezoelectric actuator according to claim 1, wherein the insulator is made of a plastic such as polyimide or tetrafluoroethylene.

  1-6. 2. The piezoelectric actuator according to claim 1, wherein a moving body is provided at one end of the piezoelectric element, and an inertial body is provided at the other end of the piezoelectric element.

  1-7. An elastic member such as a leaf spring contacting the moving peripheral surface of the moving body or a leaf spring connected to a leg of the moving body; and a screw for adjusting the frictional force by tightening the elastic member plate. 2. The piezoelectric actuator according to claim 1, comprising an adjusting member such as a nut or a nut.

2. A piezoelectric actuator having a piezoelectric element, a moving body fixed to an end of the piezoelectric element, and a fixed member slidably and frictionally engaged with the moving body, wherein the moving body and the piezoelectric element are elastically connected. A piezoelectric actuator provided with coupling means for coupling to the piezoelectric actuator.
According to this, it is possible to prevent the piezoelectric element from breaking off from the moving body due to the impact force.
2-1. 3. The piezoelectric actuator according to claim 2, wherein the elastic force of the coupling means is sufficiently smaller than the force generated by the piezoelectric element.
2-2. 3. The piezoelectric actuator according to claim 2, wherein the coupling means is a silicon-based adhesive.
2-3. 3. The piezoelectric actuator according to claim 2, wherein the coupling means is an electrically insulating material.
2-4. 3. The piezoelectric actuator according to claim 2, wherein the coupling unit is fixed to the moving body and elastically contacts the piezoelectric element.

2-5. 3. The piezoelectric actuator according to claim 2, wherein a position of the coupling means is provided on the moving body and / or the piezoelectric element on a side opposite to a fixed portion of the moving body and the piezoelectric element.
2-6. The piezoelectric actuator according to claim 2, wherein the movable body has at least two legs, and the coupling member is provided between the legs and the piezoelectric element.
2-7. 3. The piezoelectric actuator according to claim 2, wherein the movable body is configured in a cylindrical shape, and a coupling member is provided between an inner surface of the movable body and the piezoelectric element.
2-8. 3. The piezoelectric actuator according to claim 2, wherein the coupling member is an elastic body having better heat conductivity than air.
2-9. 3. The piezoelectric actuator according to claim 2, wherein the moving body is provided at one end of the piezoelectric element, and an inertial body is provided at the other end.

3. A piezoelectric element, coupling means provided at an end of the piezoelectric element, a moving body fixed to the coupling means, a stationary member fixed to the other end of the piezoelectric element, and slidable with the moving body. A piezoelectric actuator comprising a fixed member that frictionally engages with the piezoelectric actuator, wherein the coupling means is a displacement magnifying mechanism using elastic deformation.
According to this, it is possible to prevent the piezoelectric element from breaking off from the moving body due to the impact force.

4. A piezoelectric element, a moving body provided at one end of the piezoelectric element, a stationary body fixedly connected to the other end of the piezoelectric element, and a latch slidably frictionally engaged with the moving body. A piezoelectric actuator comprising a member, wherein coupling means for elastically coupling the piezoelectric element and the moving body is provided.
According to this, it is possible to prevent the piezoelectric element from breaking off from the moving body due to the impact force.
4-1. The piezoelectric actuator according to claim 4, wherein the coupling means is a silicon-based adhesive.
4-2. The piezoelectric actuator according to claim 4, wherein the coupling unit is fixed to the moving body and is in contact with the piezoelectric element.
4-3. The piezoelectric actuator according to claim 4, wherein the moving body has a cylindrical shape, and coupling means is provided between the inner surface of the cylinder and the piezoelectric element.

4-4. The piezoelectric actuator according to claim 4, wherein the coupling means is provided on a fixed portion of the moving body and the piezoelectric element and on an end of the moving body and / or the piezoelectric element on the opposite side.
4-5. The piezoelectric actuator according to claim 4, wherein the coupling member is an elastic body having better heat conductivity than air.

5. A piezoelectric element, a moving body fixed to an end of the piezoelectric element, and a fixing member slidably and frictionally engaged with the moving body, wherein the moving body has a cylindrical shape covering the piezoelectric element, and A piezoelectric actuator, wherein a member is provided with a hole that fits with the outer surface of the cylinder.
According to this, the state of the frictional engagement between the moving body and the fixed member can be stabilized.
5-1. The piezoelectric actuator according to claim 5, wherein the moving body is provided so as to cover the entire surface of the piezoelectric element.
5-2. The piezoelectric actuator according to claim 5, wherein the piezoelectric element is sealed by the moving body.
5-3. The piezoelectric actuator according to claim 5, wherein a frictional force generating means for slidably engaging the movable body and the fixed member is provided on the fixed member.

5-4. 6. The piezoelectric actuator according to claim 5, wherein the frictional force generating means is configured to be capable of changing a frictional force.
5-5. The piezoelectric actuator according to claim 5, wherein the adjustment of the frictional force generating means is adjusted using a screw.
5-6. The piezoelectric actuator according to claim 5, wherein the adjustment of the frictional force generating means is electrically adjusted.
5-7. The piezoelectric actuator according to claim 5, wherein an elastic body is used for the frictional force generating means.
5-8. The piezoelectric actuator according to claim 5, wherein the elastic body is a spring.

5-9. The piezoelectric actuator according to claim 5, wherein the spring is a coil spring.
5-10. The piezoelectric actuator according to claim 5, wherein the spring is a leaf spring.
5-11. 6. The piezoelectric actuator according to claim 5, wherein the frictional force generating means and / or the adjusting means use a generating force of a piezoelectric element.
5-12. 6. The piezoelectric actuator according to claim 5, wherein a generating force of a giant magnetostrictive element is used for the frictional force generating means and / or the adjusting means.
5-13. 6. The piezoelectric actuator according to claim 5, wherein a chemo-mechanical force is used for the frictional force generating means and / or the adjusting means.
5-14. 6. The piezoelectric actuator according to claim 5, wherein a force generated by an electromagnet is used for the frictional force generating means and / or the adjusting means.
5-15. The piezoelectric actuator according to claim 5, wherein a solenoid mechanism is used for the force generated by the electromagnet.

5-16. The piezoelectric actuator according to claim 5, wherein the attraction force of the electromagnet is used as the force generated by the electromagnet.
5-17. A piezoelectric actuator, wherein a lead wire to be connected to the piezoelectric element is drawn out of the moving body from a fixed portion side of the piezoelectric element and the moving body.
5-18. The piezoelectric actuator according to claim 5, wherein the lead wire is for grasping a vibration state of the piezoelectric element and / or for driving the piezoelectric element.
5-19. The piezoelectric actuator according to claim 5, wherein a chamfer is applied to a ridge portion in a longitudinal direction of the piezoelectric element.
5-20. 20. The piezoelectric actuator according to additional item 5-19, wherein a shape of a cross section perpendicular to the longitudinal direction of the piezoelectric element is a polygon having an octagon or more.

6. A piezoelectric element, a moving body provided at an end of the piezoelectric element, a piezoelectric actuator including a fixed member slidably and frictionally engaged with the moving body, and a driven body driven by the piezoelectric actuator; A piezoelectric actuator, wherein the driven body and the moving body are elastically connected using elasticity of the moving body of the piezoelectric actuator.
According to this, it is possible to prevent the piezoelectric element from breaking off from the moving body due to the impact force.

7. In a piezoelectric actuator that drives an optical system of an endoscope,
A moving body, a piezoelectric vibrator fixed to the moving body, a fixed member frictionally engaged with the moving body, causing a sudden displacement of the piezoelectric vibrator, and causing an impact on the moving body by the piezoelectric vibrator. Driving means for moving the moving member with respect to the fixed member by overcoming frictional engagement between the moving body and the fixed member, and adjusting a frictional force between the moving body and the fixed member. A piezoelectric actuator, comprising: According to this, when driving the optical system of the endoscope, the moment due to the force of the actuator does not affect the operation of the optical system and the actuator.
7-1. 8. The piezoelectric actuator according to claim 7, wherein the optical system of the endoscope and the piezoelectric actuator are connected by a link.
7-2. 8. The piezoelectric actuator according to claim 7, wherein the optical system of the endoscope and the actuator are connected by a gear.

8. In a piezoelectric actuator having a piezoelectric element, a moving body fixed to an end of the piezoelectric element, and a fixed member slidably frictionally engaged with the moving body, it is preferable that the moving body and the piezoelectric element are insulated. Characteristic piezoelectric actuator.
8-1. Item 8. The moving body comprises a sliding member that slides on the fixing member, and a piezoelectric element fixing portion for fixing the piezoelectric element, and the piezoelectric element fixing portion is formed of an insulating material. 3. The piezoelectric actuator according to claim 1.

2A is a longitudinal sectional view of the piezoelectric actuator according to the first embodiment, and FIG. 2B is a perspective view in which members before assembly of the piezoelectric actuator are arranged. FIG. 6 is a longitudinal sectional view of a piezoelectric actuator according to a second embodiment. FIG. 9 is a vertical sectional view of a piezoelectric actuator according to a third embodiment. Sectional drawing which follows the AA line in FIG. FIG. 14 is a vertical sectional view of a piezoelectric actuator according to a fourth embodiment. FIG. 13 is a longitudinal sectional view of a piezoelectric actuator according to a fifth embodiment. FIG. 13 is a longitudinal sectional view of a piezoelectric actuator according to a sixth embodiment. FIG. 17 is a longitudinal sectional view of the vicinity of a frictional force generating mechanism of a piezoelectric actuator according to a sixth embodiment. FIG. 14 is a longitudinal sectional view of the vicinity of a frictional force generating mechanism of a piezoelectric actuator according to a seventh embodiment. FIG. 16 is a vertical cross-sectional view of the vicinity of a frictional force generating mechanism of a piezoelectric actuator according to an eighth embodiment. FIG. 14 is a longitudinal sectional view of the vicinity of a frictional force generating mechanism of a piezoelectric actuator according to a ninth embodiment. FIG. 16 is a vertical cross-sectional view of the vicinity of a frictional force generating mechanism of a piezoelectric actuator according to a tenth embodiment. FIG. 14 is a vertical cross-sectional view of the vicinity of a frictional force generating mechanism of a piezoelectric actuator according to an eleventh embodiment. FIG. 19 is a longitudinal sectional view of the vicinity of a frictional force generating mechanism of a piezoelectric actuator according to a twelfth embodiment. FIG. 21 is a cross-sectional view of an endoscope distal end portion including a focus adjustment mechanism to which a piezoelectric actuator according to a thirteenth embodiment is applied. FIG. 21 is a sectional view of a piezoelectric actuator according to a thirteenth embodiment. The side view of the operation part of the endoscope concerning a 13th embodiment. The perspective view of the lead wire connection part of the piezoelectric element in the piezoelectric actuator concerning a 13th embodiment. FIG. 19 is an explanatory diagram showing a drive waveform for driving the piezoelectric actuator according to the thirteenth embodiment. FIG. 22 is an explanatory diagram of the operation of the piezoelectric actuator according to the thirteenth embodiment. The longitudinal section of the piezoelectric actuator concerning a 14th embodiment. (A) is a longitudinal section of a focus adjustment mechanism in an observation optical system of an endoscope incorporating a piezoelectric actuator according to a fifteenth embodiment, and (b) is a front view of a part thereof. FIG. 39 is a longitudinal sectional view of a focus adjusting mechanism in an observation optical system of an endoscope incorporating a piezoelectric actuator according to a sixteenth embodiment. The longitudinal section of the portion of the piezoelectric actuator concerning a 17th embodiment. (A) is a longitudinal sectional view showing a state in which the inner surface of the circular tube of the piezoelectric actuator according to the seventeenth embodiment and the tip of the leg of the moving body are in contact with each other, and (b) is the same as the inner surface of the circular tube and the moving body. The front view in the state where the tip part of the leg was in contact.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric actuator, 2 ... Piezoelectric element, 3 ... Moving body, 4 ... Fixed member 7 ... Strip-shaped leaf spring, 8 ... Centering member, 9 ... Mounting part, 10 ... Leg part 11 ... Sliding part, 12 ... Fitting Hole 13; frictional force adjusting section.

Claims (3)

A piezoelectric element, a moving body fixed to an end of the piezoelectric element, a stationary fixing member frictionally engaged with the moving body, and a sudden deformation of the piezoelectric element, which causes the piezoelectric element to impact on the moving body. And driving means for moving the moving body with respect to the stationary fixed member by overcoming frictional engagement between the moving body and the stationary fixed member, wherein the moving body includes the piezoelectric element. A piezoelectric actuator having a cylindrical shape that covers an element, wherein the cylindrical outer surface is configured to fit with the stationary fixing member. The piezoelectric actuator according to claim 1, wherein the movable body is configured to cover the entire surface of the piezoelectric element. 3. The piezoelectric actuator according to claim 1, wherein the stationary fixing member is provided with frictional force generating means capable of changing a frictional force between the moving body and the stationary fixing member.

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