JP2016036233A - Vibration type actuator, optical device and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration type actuator which is hard to cause the delamination between a piezoelectric element and an elastic member.SOLUTION: A vibration type actuator comprises: a vibrator 11 having a piezoelectric element 111 and an elastic member 112, which are glued to each other; a driven member 12 which is driven relatively to the vibrator 11; and a pressure-applying member 13 which applies a pressure for pressing the vibrator 11 against the driven member 12. The elastic member 112 has pressed parts 112c each extending along a predetermined direction, to which the pressure is applied by the pressure-applying member 13. The pressure-applying member 13 has: applied pressure-transmit parts 13a connected with the corresponding pressed parts 112c respectively; and pressure-application holding parts 13b. Supposing that in a region of a boundary portion of the elastic member 112 and piezoelectric element 111 glued to each other, an end point close to each pressed part 112c is defined as a point P, a D3 direction in which the pressed part 112c extends when viewed from the point P is defined as a first direction, and a D4 direction opposite to the D3 direction is defined as a second direction, each pressure-application holding part 13b is disposed at a position spaced apart from the point P in the second direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vibration type actuator used for a lens barrel or the like of an image pickup apparatus.

  An ultrasonic motor using the ultrasonic vibration of a piezoelectric element is characterized by being small and capable of obtaining a high output, capable of supporting a wide speed range, low vibration and low noise. Ultrasonic motors having such characteristics are known in various principles and shapes depending on the application. In a system in which a plurality of resonance modes are simultaneously excited in a chip-type vibrator provided with a contact portion with a driven member, elliptical motion is generated in the contact portion by the excited resonance mode. By transmitting this elliptical motion to the driven member, the driven member is driven.

  Patent Document 1 discloses an ultrasonic motor using a chip-type vibrator. The features of this method are that the vibrator is relatively small among ultrasonic motors, and that it can be easily applied to both the rotational drive and the straight drive. Therefore, an ultrasonic motor using a chip-type vibrator is suitable as an actuator for linearly driving a lens in a lens barrel or the like of a camera that requires a small and high driving force motor.

JP 2011-2554587 A

  The apparatus disclosed in Patent Document 1 uses a vibrator on which a piezoelectric element and an elastic member are attached. By applying an appropriate voltage signal to the piezoelectric element on the vibrator, vibration is excited in the vibrator, and the driven member is driven relative to the vibrator in a predetermined direction. In this apparatus, the vibrator needs to be pressurized against the driven member. In this case, when the vibrator is directly pressurized, the vibration of the vibrator is hindered. Therefore, as a method for applying pressure while preventing the inhibition of vibration, there is a method in which an elastic member is provided with a pressurized portion extending in a predetermined direction, and only the pressurized portion is pressurized. However, by applying pressure to the pressurized portion, a moment is generated to bend the elastic member to the side opposite to the side where the piezoelectric element is bonded at the boundary between the piezoelectric element and the elastic member. . This moment may cause the piezoelectric element and the elastic member to peel off. Accordingly, an object of the present invention is to provide a vibration type actuator in which peeling between the piezoelectric element and the elastic member does not easily occur.

  The vibration type actuator according to the present invention includes a vibrator in which a piezoelectric element and an elastic member are bonded, a driven member that moves relative to the vibrator by vibration of the vibrator, and the vibration by pressure. A pressing member that presses a child against the driven member and a holding member that holds the vibrator are provided. The elastic member has a pressurized part connected to the pressurized member, and the pressurized member is a pressurized transmission part connected to the pressurized part, and the driven member is driven. A pressure holding unit configured to receive a holding force from the holding member to hold the member at a position separated from the member; When the direction in which the pressurized portion extends in the elastic member is a first direction and the direction opposite to the first direction is a second direction, the first direction, the second direction, and the applied pressure When viewed from a direction orthogonal to the direction, the pressure holding portion is located on the second direction side with respect to an end point of a boundary portion between the elastic member and the piezoelectric element.

  ADVANTAGE OF THE INVENTION According to this invention, the vibration type actuator with which peeling with a piezoelectric element and an elastic member does not occur easily can be provided.

1 is an exploded perspective view illustrating an ultrasonic motor according to a first embodiment of the present invention. It is a side view showing the ultrasonic motor concerning a 1st embodiment of the present invention. It is a perspective view showing the vibrator | oscillator of the ultrasonic motor of FIG. It is a figure showing a vibration state about the vibrator | oscillator of the ultrasonic motor of FIG. It is a figure explaining the effect of a 1st embodiment. It is a perspective view showing an imaging device. It is a figure showing the lens drive device using the ultrasonic motor of FIG. It is a disassembled perspective view showing the ultrasonic motor concerning a 2nd embodiment of the present invention. It is a side view showing the ultrasonic motor concerning a 2nd embodiment of the present invention. It is a disassembled perspective view showing the ultrasonic motor which concerns on 3rd Embodiment of this invention. It is a side view showing the ultrasonic motor concerning a 3rd embodiment of the present invention. It is a disassembled perspective view showing the ultrasonic motor of a comparative example. It is a side view showing the ultrasonic motor of a comparative example.

  Hereinafter, the vibration type actuator according to each embodiment of the present invention will be described. The vibration type actuator according to each embodiment can be applied to an electronic device that is required to be small and light and have a wide driving speed range. For example, the vibration-type actuator can be applied to lens driving or the like in a lens barrel of an imaging apparatus that requires a small and high-output motor. The technical scope of the present invention includes a drive device for an optical element such as a lens or a prism, an optical device such as a lens barrel or a lens unit, and an imaging device as a device using a vibration actuator.

[First Embodiment]
An ultrasonic motor 1 according to a first embodiment of the present invention will be described. FIG. 1 is an exploded perspective view showing a configuration example of the ultrasonic motor 1. The ultrasonic motor 1 includes a vibrator 11, a driven member 12, a pressure member 13, a vibrator holder 14, and a fastening member 15.

  The vibrator 11 will be described with reference to FIG. FIG. 3 is a perspective view of the vibrator 11. The vibrator 11 has a structure in which a piezoelectric element 111 and an elastic member 112 are attached with an adhesive. The long side direction of the vibrator 11 is defined as the D1 direction, and the thickness direction of the vibrator 11 orthogonal to this direction is defined as the D2 direction.

  The piezoelectric element 111 is, for example, rectangular plate-shaped PZT (lead zirconate titanate). The elastic member 112 is, for example, a press-molded stainless steel flat plate. The vibrator 11 is driven in a predetermined direction by being excited by an appropriate vibration while being pressed against a drive target (the driven member 12 of FIG. 1 in the ultrasonic motor 1). The elastic member 112 has an elastic vibration part 112a, a plurality of contact parts 112b, and at least one pressed part 112c, and each part is molded. The elastic vibration part 112 a vibrates together with the piezoelectric element 111 due to expansion and contraction of the piezoelectric element 111. The plurality of contact portions 112b are protrusions (leg portions) provided on the elastic vibration portion 112a, and are in pressure contact with the drive target. The pressurized portion 112c extends from the elastic vibration portion 112a in a predetermined direction, and is a portion that receives a pressing force for being pressed against the driving target. In the present embodiment, two pressed parts 112c are formed at the end of the elastic vibration part 112a in the D1 direction. The elastic vibration part 112a, the contact part 112b, and the pressurized part 112c are formed by, for example, pressing a single stainless steel plate.

  When driving the driving target with the ultrasonic motor 1, the driving unit applies an appropriate electrical signal to the piezoelectric element 111. Two different vibrations are excited in the vibrator 11 by the expansion and contraction of the piezoelectric element 111. The first vibration is referred to as “feed vibration” and the second vibration is referred to as “push-up vibration”. FIG. 4A is a schematic diagram showing the vibrator 11 in a state where the feed vibration is excited. FIG. 4B is a schematic diagram showing the vibrator 11 in a state where the push-up vibration is excited.

  As shown in FIG. 4A, the vibrator 11 uses a bending secondary vibration mode as a feed vibration. In the bending secondary vibration mode, the locus R2 drawn by the tip of the contact portion 112b is substantially parallel to the drive direction (D1 direction in the drawing) of the drive target. Further, as shown in FIG. 4B, the bending primary resonance vibration mode is used as the push-up vibration in the vibrator 11. In the bending primary resonance vibration mode, the trajectory R3 drawn by the tip of the contact portion 112b is substantially parallel to the pressurizing direction (D2 direction in the figure) to the drive target. By exciting the vibrator 11 with an appropriate phase difference between the feed vibration shown in FIG. 4 (A) and the push-up vibration shown in FIG. 4 (B), as shown by the locus R1 in FIG. The part 112b draws an elliptical orbit. The elliptical motion indicated by the locus R1 is performed in a state where the contact portion 112b is in pressure contact with the drive target. Thereby, a drive object can be sent out repeatedly and can be driven relatively in the D1 direction. Note that the ultrasonic motor 1 uses a bending secondary vibration mode that is a feed vibration and a bending primary vibration mode that is a push-up vibration in order to relatively drive the drive target. As long as the driven member 12 can be relatively driven, the vibration mode is not limited to the above, and the two vibration modes may not necessarily be used.

Next, the overall configuration of the ultrasonic motor 1 will be described.
The driven member 12 shown in FIG. 1 is, for example, a stainless steel square, and is driven relative to the vibrator 11 in a predetermined direction by the vibration of the vibrator 11. The plurality of pressure members 13 are, for example, stainless plate springs. Due to the elastic deformation of the pressing member 13, a pressing force for pressing the vibrator 11 against the driven member 12 is generated. A part of the pressing member 13 and the pressed part 112c of the vibrator 11 are connected, for example, by welding. A portion of the pressurizing member 13 that is connected to the pressurized portion 112c and transmits the pressure to the vibrator 11 is referred to as a pressurizing transmission portion 13a. A portion different from the pressure transmission unit 13 a and the vibrator holder 14 are held by a fastening member 15. The vibrator holder 14 is, for example, a resin member. The vibrator holder 14 is a holding member that is connected to the vibrator 11 via the pressure member 13 and holds the vibrator 11. An annular portion of the pressure member 13 that is held by the vibrator holder 14 is referred to as a pressure holding portion 13b.

  The vibrator holder 14 is held at a position away from the driven member 12 by a predetermined distance so that an appropriate pressure is generated by elastic force by elastically deforming the pressing member 13. FIG. 2A is a side view showing the ultrasonic motor 1 in a state where the vibrator holder 14 is held at a position separated from the driven member 12 by a predetermined distance (a part is shown in cross section). . In this state, the pressurizing member 13 is elastically deformed and bent in a convex shape downward in FIG. At this time, the pressurizing force F1 is applied to the pressurized portion 112c from the pressure transmitting portion 13a. Further, when the vibrator holder 14 is held at a position separated from the driven member 12 by a predetermined distance, the pressurization holding portion 13b is restricted from moving in a direction substantially parallel to the pressing force F1. A holding force F2 in a direction substantially parallel to the applied pressure F1 is applied from the vibrator holder 14 to the pressure holding portion 13b. Since the holding force F2 works, the pressurizing member 13 does not move due to the reaction force of the pressurizing force F1, and is held at a predetermined distance when viewed from the driven member 12 side. The contact portions 112b of the vibrator 11 are brought into pressure contact with the driven member 12 by the applied pressure F1 acting on the pressurized portion 112c.

Next, the conditions which each to-be-pressurized part 112c satisfy | fills with the ultrasonic motor 1 are demonstrated.
As shown in an enlarged view in FIG. 2B, in the region where the elastic member 112 and the piezoelectric element 111 are attached, the portion to be pressed 112c is closest to the adjacent portion in the elastic vibration portion 112a. The point is described as a point P (FIG. 2B shows only the point P on one side). Further, when viewed from the point P, the first direction in which the corresponding pressurized part 112c extends from the elastic vibration part 112a is defined as a D3 direction. The pressure holding portion 13b of the pressure member 13 is disposed on the side opposite to the first direction (the side in the D4 direction) when viewed from the point P. Hereinafter, the D4 direction is the second direction.

  As shown in FIG. 2A, each of the contact portions 112b is in pressure contact with the driven member 12, and when the vibrator 11 is excited in this state, the driven member 12 relatively moves. In the ultrasonic motor 1, a leaf spring is used as the pressure member 13. Further, the pressure member 13 is used to hold the vibrator holder 14 and the vibrator 11, but the pressure member 13 is applied with pressure to press the vibrator 11 against the driven member 12. As long as it can be generated. Therefore, another mechanism may be used for holding the vibrator 11 and the vibrator holder 14.

  When viewed from the point P located in the vicinity of each pressurized portion 112c, the pressure holding portion 13b of the pressure member 13 is disposed on the second direction (D4 direction) side. In order to explain the action, a comparative example is given. The comparative example shown in FIGS. 12 and 13 has a structure in which the pressure holding unit is disposed on the first direction side when viewed from the point P. After explaining this structure, it will be compared with the ultrasonic motor 1.

  FIG. 12 is an exploded perspective view showing the configuration of the ultrasonic motor 5 of the comparative example. The ultrasonic motor 5 includes a vibrator 51, a driven member 52, a pressure member 53, a vibrator holder 54, and a fastening member 55.

  The vibrator 51 has a structure in which a piezoelectric element 511 and an elastic member 512 are attached. The elastic member 512 includes an elastic vibration part 512a and a plurality of contact parts 512b, and two pressed parts 512c are formed. The driven member 52 is relatively driven in a predetermined direction by the vibration of the vibrator 51. The plurality of pressure members 53 press the vibrator 51 against the driven member 52 by elastic deformation thereof. Each pressurizing member 53 has a pressurizing transmission portion 53 a connected to the pressed portion 512 c and a pressurizing holding portion 53 b held by the vibrator holder 54. The fastening member 55 is used to hold the pressure holding portion 53 b and the vibrator holder 54. The vibrator holder 54 holds the vibrator 51 via the pressure member 53. As shown in FIG. 13B, an end point P is set at the boundary between the piezoelectric element 511 and the elastic member 512 in the vicinity of each pressed part 512c, and the D3 direction approaching the pressing member 53 is the first. Defined as direction. The second direction is the D4 direction and is defined as the direction opposite to the D3 direction.

  The vibrator holder 54 is held at a position away from the driven member 52 by a predetermined distance so that an appropriate pressure is generated by elastic force by elastically deforming the pressing member 53. FIG. 13A is a side view showing the ultrasonic motor 5 in a state where the vibrator holder 54 is held at a position separated from the driven member 52 by a predetermined distance. In this state, the pressurizing force F1 is applied from the pressurizing transmission portion 53a to the pressurized portion 512c. Further, when the vibrator holder 54 is held at a position separated from the driven member 52 by a predetermined distance, the pressurization holding portion 53b is restricted from moving in a direction substantially parallel to the pressing force F1. A holding force F2 in a direction substantially parallel to the applied pressure F1 is applied from the vibrator holder 54 to the pressure holding portion 53b. By this holding force F2, the pressing member 53 does not move due to the reaction force of the pressing force F1, but is held at a position separated by a predetermined distance when viewed from the driven member 53. As described above, the ultrasonic motor 5 of the comparative example is different from the ultrasonic motor 1 in that the pressure holding portion 53b of the pressure member 53 is arranged in the first direction (D3 direction) when viewed from the point P. That is.

  The ultrasonic motor 1 and the ultrasonic motor 5 are compared by comparing FIG. 2 (B) and FIG. 13 (B). FIG. 2B is an enlarged view showing the vicinity of the point P of the ultrasonic motor 1. FIG. 13B is an enlarged view showing the vicinity of the point P of the ultrasonic motor 5.

First, the force F2 and the moment M1 act on the pressure holding parts 13b and 53b. The directions of the force F2 and the moment M1 are as shown in FIGS. 2B and 13B, respectively. A moment M2 is generated at the point P by the force F2 and the moment M1. Assuming that the distance between the point P and the pressure holding portions 13b and 53b is L, the magnitude of the moment M2 is expressed by Expression (1).
M2 = F2 × L-M1 Formula (1)
The magnitude of the moment M1 depends on the connection method between the pressure holding portions 13b and 53b and the vibrator holders 14 and 54, and the shape and rigidity of the pressure members 13 and 53. When the pressure members 13 and 53 are members that are easily deformed in a direction substantially parallel to the applied pressure, such as leaf springs, the moment M1 is small. In this case, the relationship between the force F2, the moment M1, and the distance L often satisfies the expression (2).
M1 <F2 × L Formula (2)
Therefore, in the ultrasonic motor 1, the direction of the moment M2 is the direction indicated by the clockwise arrow in FIG. 2B, and in the ultrasonic motor 5, the direction of the moment M2 is opposite to that in FIG. 13B. The direction is indicated by a clockwise arrow.

  In the ultrasonic motor 5 of the comparative example, the moment M2 shown in FIG. 13B tries to bend the elastic member 512 to the side opposite to the side where the piezoelectric element 511 is attached, and the stress P in the peeling direction is applied to the point P. Concentrate. For this reason, the piezoelectric element 511 and the elastic member 512 may be peeled off from the point P.

  On the other hand, in the ultrasonic motor 1, the moment M2 shown in FIG. In this case, since the elastic member 112 is bent to the side where the piezoelectric element 111 is attached, the stress σ in the compression direction concentrates on the point P. Therefore, compared with the ultrasonic motor 5, the ultrasonic motor 1 has an effect that the vibrator 111 and the elastic member 112 are less likely to be peeled off. Here, with reference to FIG. 5, the operation | movement which the structure of the ultrasonic motor 1 has is demonstrated concretely. The calculation result by the FEM (Finite Element Method) simulation will be described below.

  FIG. 5A is a top view of the ultrasonic motor 1 and shows the vibrator 11 and the pressure member 13. The definition of the point P and the first direction (D3 direction) and the second direction (D4 direction) are as described above. FIG. 5B is an enlarged side view showing the vicinity of the point P of the ultrasonic motor 1. FIG. 5C is a graph showing the result of simulation. The horizontal axis represents the coordinates X of the connecting portion with respect to the point P. The connection part is a connection part between the pressure holding part 13 b and the vibrator holder 14. The vertical axis represents the stress σ acting on the point P. The graph which calculated the stress (sigma) which arises in the point P when the point P is made into the origin and the pressurization holding part 13b exists in the position X of the 2nd direction side is illustrated. The sign of the stress σ is positive in the compression direction. However, in order to observe only the action related to the structure of the present embodiment, the calculation was performed with the value of the moment M1 acting on the pressure holding unit 13b set to zero. Note that a method of changing the moment acting on the pressurizing and holding unit 13b will be described in an embodiment described later.

  As shown in a dotted frame S1 in FIG. 5C, when the coordinate X is a negative value, the stress σ is a negative value. This represents the stress σ when the pressure holding portion 53b is on the first direction side when viewed from the point P in the ultrasonic motor 5. That is, the stress σ acts in the direction in which the piezoelectric element 511 and the elastic member 512 are peeled off by the moment M2 generated at the point P. On the other hand, as shown in the dotted frame S2 in FIG. 5C, when the coordinate X is a positive value, the stress σ is a positive value. This represents the stress σ when the pressure holding portion 13b is on the second direction side when viewed from the point P in the ultrasonic motor 1. That is, the stress M is acting on the piezoelectric element 111 and the elastic member 112 in the compression direction by the moment M2 generated at the point P. From this simulation result, the action of the structure of the ultrasonic motor 1 is concretely supported.

  In the present embodiment, when the point P and the first direction and the second direction are defined for each pressurized portion 112c, the pressure holding portion 13b is disposed on the second direction side when viewed from the point P. Yes. As a result, a moment M2 is generated which tends to bend the elastic member 112 to the side where the piezoelectric element 111 is attached. That is, the stress in the compression direction acts on the point P due to the moment M2 (the stress in the compression direction is generated between the piezoelectric element 111 and the elastic member 112), so that the piezoelectric element 111 and the elastic member 112 are hardly separated. Can be obtained.

  The ultrasonic motor 1 described in the present embodiment uses a leaf spring as the pressure member 13 and can hold the vibrator 11 and the vibrator holder 14 via the pressure member 13. In this case, there is no need to separately provide a mechanism for holding the vibrator 11 and the vibrator holder 14, which contributes to a reduction in the number of parts, cost reduction, and size reduction.

[Application example]
Hereinafter, as an example of application to a drive device for an optical element, a lens barrel that drives a lens straightly using an ultrasonic motor 1 will be described.

  FIG. 6 is a perspective view of the camera 9 provided with the lens barrel 91. Inside the lens barrel 91, the focus lens is driven in the optical axis (a-axis) direction by the ultrasonic motor 1. FIG. 7A is a cross-sectional view of the focus lens driving unit at a cutting plane C passing through the optical axis of the lens barrel 91. FIG. 7B is a cross-sectional view of the focus lens driving unit at a cross section perpendicular to the optical axis (cross section DD in FIG. 7A).

  A focus lens 911 is supported in the lens barrel 91 so as to be movable along the optical axis. The focus lens 911 is fixed to the lens holder 912. The lens holder 912 is provided with a round hole portion 912a and a long hole portion 912b, and a rod-shaped guide member 913 is inserted into each hole portion. Accordingly, the focus lens 911 and the lens holder 912 are supported so as to be movable only in the optical axis direction.

  The ultrasonic motor 1 is disposed adjacent to the lens holder 912. The ultrasonic motor 1 includes a vibrator 11, a driven member 12, a pressure member 13, and a vibrator holder 14. Since the driven member 12 is fixed to the lens barrel exterior member 918, the vibrator 11 can move relative to the driven member 12. The lens barrel exterior member 918 is a fixing member for the driven member 12. On the other hand, the vibrator holder 14 is supported so as to be movable only in the optical axis direction with respect to the lens barrel exterior member 918 via a plurality of rolling members 915. The rolling member 915 has a spherical shape, and is sandwiched between the groove formed in the inner portion of the lens barrel exterior member 918 and the vibrator holder 14.

When the drive unit excites the vibrator 11 in this state, the vibrator 11 moves relative to the driven member 12. That is, since the driven member 12 is fixed to the lens barrel exterior member 918, the vibrator 11, the pressure member 13, and the vibrator holder 14 move in the optical axis direction. The vibrator holder 14 is provided with a projecting connection portion 14a. The connecting portion 14 a is connected by being fitted into a hole formed in the lens holder 912. Therefore, the lens holder 912 and the focus lens 911 can move in the optical axis direction in synchronization with the movement of the vibrator 11.
The lens barrel 91 that drives the lens using the ultrasonic motor 1 has a structure in which the piezoelectric element and the elastic member are unlikely to peel off in the vibrator 11. Therefore, highly reliable lens driving can be realized with an optical apparatus or an imaging apparatus.

[Second Embodiment]
Next, the ultrasonic motor 2 according to the second embodiment will be described with reference to FIG. FIG. 8 is an exploded perspective view showing the configuration of the ultrasonic motor 2. The ultrasonic motor 2 includes a vibrator 21, a driven member 22, a pressure member 23, a vibrator holder 24, and a fastening member 25.

  The vibrator 21 has a structure in which a piezoelectric element 211 and an elastic member 212 are attached with an adhesive. The elastic member 212 is formed with an elastic vibration part 212a, a contact part 212b, and two pressed parts 212c. The driven member 22 is relatively driven in a predetermined direction by the vibration of the vibrator 21. The pressing member 23 presses the vibrator 21 against the driven member 22 by elastic deformation. The pressure member 23 includes a pressure transmission part 23a and a pressure holding part 23b. The pressure transmission part 23a is formed as a bent shape part and is connected to the pressurized part 212c. The pressure holding part 23 b and the vicinity thereof are formed in an S-shaped crank shape and are held by the vibrator holder 24. The fastening member 25 is inserted into the annular part of the pressure holding part 23 b and fastened to the vibrator holder 24 to be used for holding. The vibrator holder 24 holds the vibrator 21 via the pressure member 23. As shown in FIG. 9B, as in the case of the first embodiment, an end point P is set at the boundary between the piezoelectric element 211 and the elastic member 212 in the vicinity of each pressed part 212c, and the direction D3 is set. Is defined as the first direction, and the D4 direction is defined as the second direction.

  The vibrator holder 24 is held at a position spaced apart from the driven member 22 by a predetermined distance so that the pressing member 23 is elastically deformed and an appropriate pressure is generated by the elastic force. FIG. 9A is a side view showing the ultrasonic motor 2 in a state where the vibrator holder 24 is held at a position separated from the driven member 22 by a predetermined distance. In this state, the pressurizing force F1 is applied from the pressurizing transmission portion 23a to the pressurized portion 212c. By holding the vibrator holder 24 at a position separated from the driven member 22 by a predetermined distance, the pressurization holding portion 23b is restricted from moving in a direction substantially parallel to the applied pressure F1. A holding force F2 in a direction substantially parallel to the pressing force F1 is applied from the vibrator holder 24 to the pressure holding portion 23b. By this holding force F2, the pressing member 23 does not move due to the reaction force of the pressing force F1, but is held at a position separated by a predetermined distance when viewed from the driven member 23. In the ultrasonic motor 2, the pressurization holding portion 23 b of the pressurizing member 23 is arranged on the second direction (D4 direction) side when viewed from the point P in the positional relationship between each pressed portion 212 c and the point P. ing. Further, after passing through the part 23c extending in the second direction from the pressure holding part 23b on the path when the pressure member 23 is traced from the pressure holding part 23b to the pressure transmission part 23a, the pressure transmission part The shape reaches 23a. In other words, the pressure member 23 has a first portion extending in the D4 direction from the annular portion of the pressure holding portion 23b (insertion portion of the fastening member 25), and the direction reversed from this portion in the D3 direction. A second portion is provided that extends to. A crank-shaped portion is further continuously connected to the pressurizing transmission portion 23a from the second portion.

As shown in an enlarged view in FIG. 9B, in the vicinity of the point P, as in the case of the first embodiment, the force F2 and the moment M1 act on the pressure holding portion 23b. However, the directions of the force F2 and the moment M1 are as shown in FIG. 9B, and the direction of the moment M1 is opposite to that of the ultrasonic motor 1 shown in FIG. The reason is that a portion 23c extending in the D4 direction is formed on a path that follows the pressure member 23 from the pressure holding portion 23b to the pressure transmission portion 23a. At this time, the moment M2 is generated at the point P by the force F2 and the moment M1. The magnitude of the moment M2 is expressed by Expression (3). L represents the distance between the point P and the pressure holding part 23b.
M2 = F2 × L + M1 Formula (3)
In this embodiment, as can be seen by comparing with “M2 = F2 × L−M1” in Expression (1), the elastic member 212 is bent in the direction to which the piezoelectric element 211 is attached. A larger moment acts.

  As described above, in the ultrasonic motor 2, in the positional relationship between each pressurized portion 112c and the point P, the pressure holding portion 23b is disposed on the second direction (D4 direction) side as viewed from the point P. ing. Further, a portion 23c extending in the second direction is formed at a portion bent from the pressure holding portion 23b into an S-shaped crank shape. As a result, a moment M2 is generated to bend the elastic member 212 to the side where the piezoelectric element 211 is attached, and the magnitude of M2 is larger than that of the first embodiment. A stress in the compression direction acts on the point P by the moment M2. When a stress in the compression direction is generated between the piezoelectric element 211 and the elastic member 212, an effect that the piezoelectric element 211 and the elastic member 212 are hardly peeled off can be obtained. Note that the configuration of the lens driving device using the ultrasonic motor 2 according to the present embodiment is the same as that of the first embodiment, and a description thereof will be omitted.

[Third Embodiment]
Next, the ultrasonic motor 3 according to the third embodiment will be described with reference to FIG. FIG. 10 is an exploded perspective view showing the configuration of the ultrasonic motor 3. The ultrasonic motor 3 includes a vibrator 31, a driven member 32, a pressure member 33, and a vibrator holder 34.

  The vibrator 31 has a structure in which a piezoelectric element 311 and an elastic member 312 are attached with an adhesive. The elastic member 312 is formed with an elastic vibration part 312a, a contact part 312b, and two pressed parts 312c. The driven member 32 is relatively driven in a predetermined direction by the vibration of the vibrator 31. The pressure member 33 presses the vibrator 31 against the driven member 32 by elastic deformation. The plurality of pressure members 33 include a pressure transmission part 33a and a pressure holding part 33b. The pressure transmission part 33a is formed as a bent shape part, and is connected to the pressurized part 312c. The pressure holding portion 33 b is formed in a V shape and is connected to the vibrator holder 34. The vibrator holder 34 is provided with a plurality of curved surface portions 34a for holding the pressure holding portion 33b. The pressurizing and holding part 33 b of the pressurizing member 33 is bent so as to be fitted to the curved surface part 34 of the vibrator holder 34. In a state where the vibrator 11 is in pressure contact with the driven member 12, the curved surface portion 34a and the pressure holding portion 33a are fitted and connected. The vibrator holder 34 holds the vibrator 31 via the pressure member 33. As shown in FIG. 11 (B), the end point P is set at the boundary between the piezoelectric element 311 and the elastic member 312 in the vicinity of each pressurized part 312c as in the case of the first embodiment, and the direction D3 is set. Is defined as the first direction, and the D4 direction is defined as the second direction.

  The vibrator holder 34 is held at a position away from the driven member 32 by a predetermined distance so that the pressing member 33 is elastically deformed and an appropriate pressure is generated by the elastic force. FIG. 11A is a side view of the ultrasonic motor 3 in a state where the transducer holder 34 is held at a position separated from the driven member 32 by a predetermined distance. In this state, the pressurizing force F1 is applied from the pressurizing transmission portion 33a to the pressurized portion 312c. When the vibrator holder 34 is held at a position separated from the driven member 32 by a predetermined distance, the pressurization holding portion 33b is restricted from moving in a direction substantially parallel to the applied pressure F1. A holding force F2 in a direction substantially parallel to the pressing force F1 is applied from the vibrator holder 34 to the pressure holding portion 33b. Due to the holding force F <b> 2, the pressing member 33 does not move due to the reaction force of the pressing force F <b> 1 but is held at a position separated by a predetermined distance when viewed from the driven member 33. In the ultrasonic motor 3, in the positional relationship between each pressurized portion 312 c and the point P, the pressure holding portion 33 b of the pressure member 33 is arranged on the second direction (D4 direction) side as viewed from the point P. ing. In addition, the curved surface portion 34a and the pressure holding portion 33b are rotatably held around an axis in a direction substantially parallel to the D5 direction perpendicular to the paper surface of FIGS. 11 (A) and 11 (B). The D5 direction is a direction orthogonal to the first direction (D3 direction) and the direction of applied pressure (D2 direction).

As shown in an enlarged view in FIG. 11B, a force F2 is applied to the pressure holding portion 33b. The pressure holding portion 33b and the curved surface portion 34a are held rotatably around the axis in the direction D5, and the moment M1 does not act on the pressure holding portion 33b. At this time, a moment M2 is generated at the point P by the force F2. The magnitude of the moment M2 is expressed by equation (4). L represents the distance between the point P and the pressure holding part 33b.
M2 = F2 × L Formula (4)
In the present embodiment, as can be seen by comparing with “M2 = F2 × L−M1” in Expression (1), the elastic member 312 is more bent in the direction in which the piezoelectric element 311 is to be bent. A big moment acts.

  As described above, in the ultrasonic motor 3, in the positional relationship between each pressed part 312c and the point P, the pressure holding part 33b is disposed on the second direction (D4 direction) side as viewed from the point P. ing. Further, the pressurizing and holding unit 33b is held by the vibrator holder 34 so as to be rotatable about an axis in a direction substantially parallel to the direction orthogonal to the first direction (D3 direction) and the direction of the applied pressure (D2 direction). Yes. As a result, a moment M2 is generated to bend the elastic member 312 to the side where the piezoelectric element 311 is attached. A stress in the compression direction acts on the point P by the moment M2. When stress in the compression direction is generated between the piezoelectric element 311 and the elastic member 312, an effect is obtained in which the piezoelectric element 311 and the elastic member 312 are not easily separated. Note that the configuration of the lens driving device using the ultrasonic motor 3 according to the present embodiment is the same as that of the first embodiment, and a description thereof will be omitted.

1, 2, 3 Ultrasonic motor 11, 21, 31 Vibrator 111, 211, 311 Piezoelectric element 112, 212, 312 Elastic member 112a, 212a, 312a Elastic vibration part 112b, 212b, 312b Contact part 112c, 212c, 312c Covered Pressure member 12, 22, 32 Driven member 13, 23, 33 Pressure member 14, 24, 34 Vibrator holder

Claims (10)

A vibrator on which a piezoelectric element and an elastic member are attached;
A driven member that moves relative to the vibrator by vibration of the vibrator;
A pressure member that presses the vibrator against the driven member by an applied pressure; and
A vibration type actuator comprising a holding member for holding the vibrator,
The elastic member has a pressurized portion connected to the pressure member,
The pressurizing member includes a pressurizing transmission unit connected to the pressurized member, and a pressurizing holding unit that receives from the holding member a holding force for holding the pressurizing member at a position separated from the driven member. Have
When the direction in which the pressurized portion extends in the elastic member is a first direction and the direction opposite to the first direction is a second direction, the first direction, the second direction, and the applied pressure When viewed from a direction orthogonal to the direction, the vibration holding type is characterized in that the pressure holding part is located on the second direction side with respect to an end point of a boundary part between the elastic member and the piezoelectric element. Actuator.   2. The vibration type actuator according to claim 1, wherein the elastic member includes an elastic vibration part that vibrates together with the piezoelectric element, and a contact part that press-contacts the driven member.   The end point of the boundary between the elastic member and the piezoelectric element is located on the first direction side in the elastic vibration part in the region where the elastic member and the piezoelectric element are attached, and the end point The vibration type actuator according to claim 2, wherein the pressurizing and holding unit is disposed at a position separated from the first direction in the second direction.   4. The movement of the pressurizing and holding portion in a direction parallel to the pressurizing force is restricted by the holding member being positioned away from the driven member. The vibration type actuator according to claim 1.   The vibration type actuator according to any one of claims 1 to 4, wherein the pressure member is a leaf spring.   The pressure member includes a first portion extending from the pressure holding portion in the second direction, and a second portion extending from the first portion to the first direction and extending in the direction. 6. The vibration type actuator according to claim 1, wherein the vibration type actuator is connected to the pressurizing transmission portion from the second portion.   The pressurizing and holding portion is held by the holding member so as to be rotatable about an axis in a direction parallel to the first direction and a direction orthogonal to the direction of the applied pressure. 6. The vibration type actuator according to any one of 5 above. A vibration type actuator according to any one of claims 1 to 7,
An optical device, wherein an optical element is driven by the vibration actuator.   The optical apparatus according to claim 8, wherein the optical element is driven by the vibrator that moves relative to a driven member. A vibration type actuator according to any one of claims 1 to 7,
An imaging apparatus, wherein an optical element is driven by the vibration actuator.

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