JP6525640B2 - Vibration type actuator, ultrasonic motor and lens barrel - Google Patents

Description

The present invention relates to a vibration type actuator , an ultrasonic motor and a lens barrel .

  Conventionally, an ultrasonic motor has been adopted as a driving source of a camera or a lens, taking advantage of features such as silent operation, high torque output, and low speed to high speed driving. The ultrasonic motor secures the piezoelectric element and the diaphragm with an adhesive to form a vibrator, and applies a high frequency voltage to the piezoelectric element to excite ultrasonic vibration in the vibrator. In Patent Document 1, a primary bending vibration mode in which the frictional contact portion of the vibrator vibrates in the pressing direction and a secondary bending vibration mode vibrating in the driving direction are combined to generate an elliptical vibration in the frictional contact portion. An ultrasonic motor is disclosed.

JP, 2014-72986, A

  However, in the ultrasonic motor disclosed in Patent Document 1, since the primary bending vibration mode is more easily deformed, the vibration amplitude becomes larger than necessary, and the driving efficiency is lowered.

The present invention is made in view of the above-mentioned subject, and an object of the present invention is to provide a vibration type actuator which reduced a fall of driving efficiency.

A vibration-type actuator according to an embodiment of the present invention includes a vibrator in which a piezoelectric element is attached to a diaphragm having a sliding portion, and the sliding portion is elliptical due to a plurality of orthogonal vibrations excited by the piezoelectric element. A member in frictional contact with the sliding portion by vibrating, and a vibration-type actuator in which the vibrator moves relative to each other, wherein the vibrating plate is in a longitudinal direction and a lateral direction with respect to the piezoelectric element. protruding portions have a, the protruding portion, the longitudinal direction of the protrusion amount is larger than the protruding amount of the lateral direction, the said piezoelectric element, a flexible substrate such withdrawal direction is parallel to the lateral direction have attached, a copper foil provided on the flexible substrate conducting with the electrodes of the piezoelectric element, the longitudinal direction is divided into a plurality, that are connected above the transverse direction And features.

According to the present invention, it is possible to provide a vibration-type actuator in which the lowering of the driving efficiency is reduced by configuring the vibrating plate to have the protruding portion in the longitudinal direction and the short direction with respect to the piezoelectric element.

It is an exploded perspective view of a vibration type actuator of this embodiment. It is a figure which shows the state which unitized and each member was integrated. It is an expansion perspective view showing the joined state of a vibrator and a support member. It is an expanded sectional view which shows the state which unitized and each member was integrated. It is a figure which shows the shape of the vibrator | oscillator of this embodiment. It is a figure which shows the node and antinode position of the vibration of two bending vibration modes. It is a graph which shows the size of distortion of two bending vibration modes. It is a figure which shows the relationship between the frequency of voltage, and the amplitude of an elliptical vibration. It is a figure which shows the shape of the flexible substrate of this embodiment. It is a figure which shows the state which the flexible substrate stuck to the vibrator | oscillator. It is a figure which shows the relationship between the frequency of the conventional voltage, and the amplitude of an elliptical vibration.

  Hereinafter, embodiments of the present invention will be described using the drawings. In addition, although the ultrasonic motor of this embodiment demonstrates the linear-motion drive type motor unitized as a drive actuator, such as a lens-barrel for digital cameras, to an example, a use application is not limited to this.

  First, FIG. 1 is an exploded perspective view of a vibration-type actuator according to the present embodiment. The vibration-type actuator shown in FIG. 1 is an ultrasonic motor. Here, in the present embodiment, the direction in which the vibrator 109 moves due to the elliptical motion generated in the vibrator 109 is defined as the X direction. Further, the pressure direction by the spring member 107 is defined as the Z direction. Then, in the Z direction, the direction in which the vibrator 109 moves away from the driven portion 101 is defined as + Z direction, and the direction in which the vibrator 109 approaches the driven portion 101 is defined as −Z direction. Furthermore, a direction perpendicular to the X direction and the Z direction is defined as a Y direction. The same members are illustrated with the same symbols.

  The fixed base 110 holds the entire unit of the linear drive motor. The driven unit 101 includes a contact surface 101 a with which the vibrator 109 is in pressure contact. The driven unit 101 is fixed to the fixing base 110 by two fixing screws 111. The diaphragm 102 contacts the contact surface 101 a in a pressure contact state accompanied by a pressure. The piezoelectric element 103 is fixed to the diaphragm 102 by an adhesive or the like. Then, by applying a voltage to the piezoelectric element 103 in a state in which the piezoelectric element 103 is fixed to the diaphragm 102, ultrasonic vibration can be generated, and an elliptical motion can be generated in the diaphragm 102. In the ultrasonic motor of the present embodiment, the vibrator 109 is configured by the diaphragm 102 and the piezoelectric element 103.

  The blocking member 115 blocks the ultrasonic vibration of the piezoelectric element 103 so as not to be transmitted to other parts, and prevents the propagation of the ultrasonic vibration to the small base 104 without attenuating the ultrasonic vibration of the piezoelectric element 103. . The material of the blocking member 115 is preferably felt cloth. The small base 104 is in surface contact with the piezoelectric element 103 via the blocking member 115, and transmits the pressing force of the spring member 107 to the piezoelectric element 103.

  The holding member 105 holds components around the vibrator 109. The pressure member 106 is fitted in the through hole portion 108 a of the pressure receiving member 108, and is held movably only in a direction substantially perpendicular to the contact surface 101 a of the driven portion 101. Then, the pressing force from the spring member 107 is transmitted to the vibrator 109 via the blocking member 115 and the small base 104, and the vibrator 109 is brought into pressure contact with the driven portion 101.

  The spring member 107 is formed of a compression coil spring, one end of which is fixed by the pressure receiving member 108, and the other end of which transmits a pressing force to the pressure member 106, the vibrator 109 and the driven portion 101. Make pressure contact. The pressure member 106 and the spring member 107 are pressure means in the present embodiment. The pressure receiving member 108 is in the form of a circular plate with a circular hole at the center, and is screwed and fixed to the screw portion 105 b of the holding member 105 by the screw portion formed on the outer peripheral side surface. Further, the pressing member 106 is fitted and held by the fitting hole portion 108 a which is a round hole opened at the center.

  The support member 114 is formed in a thin plate shape, and has rigidity weaker in the Z direction than in the X direction. The diaphragm 102 is interposed between the diaphragm 102 and the holding member 105, and the diaphragm 102 can freely move in the Z direction with respect to the holding member 105, but the position can be fixed in the X direction without rattling. The support member 114 is fastened together with the holding plate 113 to the holding member 105 by two fixing screws 112. Further, since the pressing plate 113 is disposed with a predetermined amount of clearance from the vibrator 109, the vibrator 109 abuts on the pressing plate 113 when the vibrator 109 moves in the -Z direction by a predetermined amount or more. It can not be moved further. With this configuration, the pressing plate 113 regulates the movement of the vibrator 109 in the -Z direction by a predetermined amount or more.

  The rolling balls 116 intervene between the groove formed in the holding member 105 and the groove formed in the top plate 117, thereby supporting the holding member 105 on the top plate 117 by rolling. The top plate 117 holds the holding member 105 by rolling by holding the holding member 105 holding the vibrator 109 between the driven portion 101 and the top plate member 117. Further, the top plate 117 is fixed to the fixing base 110 by four fixing screws 118. As described above, each member is incorporated and unitized as an ultrasonic motor.

  Next, FIG. 2 is a figure which shows the state which integrated each member unitized as an ultrasonic motor. FIG. 2A is a view of a state where each member is incorporated as viewed from the + Z direction, and FIG. 2B is a view as viewed from the -Y direction. The driven unit 101 is fixed to the fixing base 110 by two fixing screws 111. Further, the top plate 117 is fixed to the fixing base 110 at the four corners by four fixing screws 118. At the center of the top plate 117, a rectangular opening 117a is open, and a protrusion 105c of the holding member 105 protrudes from the rectangular opening 117a.

  The diaphragm 102 is in contact with the driven portion 101. The diaphragm 102 is fixed to the holding member 105 via a thin plate-shaped support member 114. Therefore, the diaphragm 102 can freely move in the Z direction with respect to the holding member 105 by the deformation of the support member 114, but can be fixed in position without displacement in the X direction.

  Then, when relative movement in the X direction occurs between the vibrator 109 and the driven unit 101 due to the elliptical motion generated in the vibrator 109, the fixing base 110, the driven unit 101, the fixing screw 111, and the ceiling The plate 117 and the fixing screw 118 serve as a fixing portion. On the other hand, the blocking member 115 including the vibrator 109, the small base 104, the fixing screw 112, the pressing plate 113, the supporting member 114, the pressing member 106, the spring member 107, the pressing member 108, and the like. The holding member 105 is a movable portion. That is, the ultrasonic motor of the present embodiment is a self-propelled motor unit in which the vibrator 109 serving as the drive source is movable. When actually incorporated into a lens barrel or the like, the holding member 105 is connected to a focusing mechanism or a zoom mechanism and driven.

  Next, details of the components of the ultrasonic motor will be described. FIG. 3 is an enlarged perspective view showing a bonded state of the vibrator and the support member, as viewed from the -Z direction. At the central bonding portion 102 a of the diaphragm 102, two protrusions are formed. The contact portion (sliding portion) 102 b is a surface that is formed on the upper end surface of the protrusion and is in frictional contact with the contact surface 101 a of the driven portion 101. Further, the two contact portions 102b are formed on the same plane, and in order to improve the contact state with the contact surface 101a of the driven portion 101, they are finished to a uniform surface by polishing or the like in the manufacturing process.

  On the other hand, the piezoelectric element 103 is fixed by an adhesive or the like on the back surface side (the surface opposite to the surface on which the two protruding portions are formed) of the bonding portion 102a shown in FIG. The method of fixing the back surface of the bonding portion 102 a to the piezoelectric element 103 is not limited as long as the bonding is performed. The piezoelectric element 103 is formed by laminating and integrating a plurality of piezoelectric element films. Then, a desired AC voltage is applied to the stacked piezoelectric elements 103 to excite them, and two bending vibration modes are excited on the diaphragm 102 to which the piezoelectric elements 103 are fixed. At this time, by setting the vibration phases of the two bending vibration modes to be a desired phase difference, an elliptical motion as shown by an arrow occurs in the contact portion 102b. Then, the above-mentioned elliptical motion is generated by the vibrator 109 shown in FIGS. 1 and 2 and transmitted to the contact surface 101a of the driven part 101, whereby the vibrator 109 itself is driven in linear motion with respect to the driven part 101. can do.

  Next, at both ends of the diaphragm 102, two bonding portions 102c are formed for bonding to the lower stepped portion 114a formed on both sides of the support member 114. The diaphragm 102 is joined to the support member 114 by welding or adhesion at the joint portion 102c, but the method is not limited as long as the diaphragm 102 and the support member 114 are joined.

  Two arm portions 102d are formed between the two joint portions 102c and the joint portion 102a, and the joint portion 102a to which the piezoelectric element 103 is fixed is fixed to the support member 114 via the arm portions 102d. Be done. The arm portion 102d has a thin shape with respect to the bonding portion 102a and the bonding portion 102c in order to make it difficult to transmit the vibration generated in the bonding portion 102a to the bonding portion 102c. In other words, the support member 114 realizes a connection configuration that does not inhibit the vibration generated in the joint portion 102 a by the arm portion 102 d. The diaphragm 102 is fixed to the holding member 105 via the thin plate-shaped support member 114. Thus, the diaphragm 102 can freely move relative to the holding member 105 in the Z direction, which is the pressing direction, but is fixed to the holding member 105 without displacement in the X direction, which is the driving direction.

  Next, FIG. 4 is an enlarged sectional view showing a state in which each member of the ultrasonic motor is incorporated. In FIG. 4, the driven portion 101 is a lower side. FIG. 4A is a cross-sectional view in a plane perpendicular to the Y-axis shown in FIG. 2 and passing through the center of the pressure member 106. FIG. 4B is a cross-sectional view taken along a plane perpendicular to the X-axis shown in FIG. 2 and passing through the center of the pressure member 106. Further, dotted lines 201 shown in FIGS. 4A and 4B are center lines that pass through the center of gravity of the contact portion 102b in contact with the contact surface 101a of the diaphragm 102 and include the normal to the contact surface 101a.

  The contact portion 102 b abuts on the contact surface 101 a of the driven portion 101 and is in a pressure contact state. Further, in the diaphragm 102, the bonding portions 102c at both ends are bonded to the support member 114 at two step portions 114a. The piezoelectric element 103 is in surface contact with the small base 104 via the blocking member 115.

  The holding member 105 is provided with two hole portions 105 a, and the two shaft portions 104 c formed in the small base 104 are fitted. The two hole portions 105 a provided in the holding portion 105 have an elongated hole shape extending in the X direction, and the small base 104 can be inclined to some extent. A contact portion 104 b is provided at the upper center of the small base 104. The contact portion 104b has an arc shape in the cross section of FIG. 4A, and has a shape of a part of a cylinder extending in the depth direction of the sheet (in the left and right direction in FIG. 4B). The lower end surface 106a of the pressure member 106 is in line contact with the contact portion 104b.

  Since the lower end surface 106a of the pressing member 106 is formed flat, the line contact portion with the contact portion 104b is long in the paper surface depth direction of FIG. 4A (left and right direction in FIG. 4B). Line contact. Therefore, in the cross section in FIG. 4A, the small base 104 is configured to be able to tilt. As a result, even if a dimensional error or an assembly error at the time of manufacture or an inclination of a member occurs due to a disturbance, the small base 104 so that the contact portion 102b of the diaphragm 102 follows the contact surface 101a of the driven portion 101. Can be maintained in a good pressure contact state.

  A screw hole 105 b is formed in the holding member 105, and a screw portion 108 b provided on the outer diameter side surface of the pressure receiving member 108 is screwed. Adjustment of the pressure is performed by changing the screwed amount according to the part variation. A structure in which the pressing member 106 can move only in the Z direction by the fitting shaft portion 106 b of the pressing member 106 being fitted and held in the fitting hole 108 a formed at the center of the pressure receiving member 108. It has become.

  The top plate 117 is fixed to the fixed base 110 and plays a role of receiving a reaction force when the contact portion 102b of the diaphragm 102 is brought into pressure contact with the contact surface 101a of the driven portion 101 by the spring force of the spring member 107. ing. At that time, the rolling ball 116 is sandwiched between the groove portion 117a formed in the top plate 117 and the groove portion 105d formed in the holding member 105, so that the holding member 105 and the top plate 117 are supported by rolling. ing. Thereby, while receiving the reaction force of the pressure contact in the Z direction, the frictional resistance when moving in the X direction is minimized.

  Further, the rolling ball is sandwiched between the groove portion 117a of the top plate 117 and the groove portion 105d of the holding member 105, whereby the position in the Y direction is determined. In the ultrasonic motor according to the present embodiment, the holding member 105 is supported in rolling without being inclined with respect to the top plate 117 by receiving the spring force of the spring member 107 by the four rolling balls 116. A blocking member 115 is sandwiched between the piezoelectric element 103 and the small base 104. The blocking member 115 uses a material having a function of blocking the propagation of vibration without inhibiting the vibration, so that the propagation of the vibration to the small base 104 is not inhibited without inhibiting the ultrasonic vibration of the piezoelectric element 103. suppress. Moreover, as a material suitable for the blocking member 115, a felt cloth etc. may be mentioned.

  In order to transmit the pressing force for bringing the contact portion 102 b into pressure contact with the contact surface 101 a of the driven portion 101, the vibrator 109 needs to be able to move freely in the Z direction. In addition, in order to drive the holding member 105 coupled to the focusing mechanism and the zoom mechanism with high accuracy, the vibrator 109 needs to be held by the holding member 105 without rattling. Therefore, the vibrator 109 is fixed to the holding member 105 via the support member 114 formed in a thin plate shape. As a result, it can move freely in the Z direction and can be driven in the X direction without backlash.

  FIG. 5 is a view showing a transducer of the ultrasonic motor of the present embodiment. FIG. 5 is a view of the vibrator 109 as seen from the + Z direction. The diaphragm 102 and the piezoelectric element 103 constitute a vibrator 109, and the diaphragm 102 and the piezoelectric element 103 have a shape longer in the X direction than in the Y direction. Here, the X direction is defined as a longitudinal direction, and a Y direction and a lateral direction. Next, an electrode formed on the flexible substrate bonding surface of the piezoelectric element 103 will be described with reference to FIG. A GND electrode region 103c is disposed at the + Y end between the first electrode region 103a and the second electrode region 103b. Further, the vibrating plate 102 protrudes in the longitudinal direction and the short direction with respect to the piezoelectric element 103 in the direction in which the vibrating plate 102 and the piezoelectric element 103 are fixed to each other.

  Since the piezoelectric element 103 is easily broken by a brittle material, there is a problem that when the piezoelectric element 103 protrudes from the vibrating plate 102, the protruding portion is easily broken. Therefore, the vibration plate 102 is configured to protrude beyond the piezoelectric element 103 by a larger amount than the bonding error amount between the piezoelectric element 103 and the vibration plate 102. As a result, the piezoelectric element 103 is always stuck to the metal-made diaphragm 102 with high ductility, so cracking of the piezoelectric element 103 can be reduced.

  The amount of protrusion of the diaphragm 102 with respect to the piezoelectric element 103 is configured such that the amount of protrusion 123 in the longitudinal direction is larger than the amount of protrusion 124 in the short direction. The longitudinal direction protruding portion 102 e is a portion where the diaphragm 102 protrudes in the longitudinal direction (X direction) with respect to the piezoelectric element 103. The longitudinal protruding portions 102 e are located on both sides of the longitudinal end of the diaphragm 102.

  FIGS. 6A and 6B are diagrams showing the positions of the nodes and antinodes of the two bending vibration modes and the free end. FIG. 6A shows the positions of nodes and antinodes in the second order bending vibration mode in the X direction. The vibrating plate 102 and the piezoelectric element 103 are fixed and integrated to form a vibrator 109. By applying a high frequency AC voltage to the piezoelectric element 103, the piezoelectric element 103 expands and contracts, but the diaphragm 102 does not expand and contract. Therefore, the expansion difference between the piezoelectric element 103 and the diaphragm 102 causes the vibrator 109 to move in the X direction. Excite the second order bending vibration mode of. 121a, 121b, and 121c shown in FIG. 6A are node positions of the secondary bending vibration mode. Reference numerals 122a and 122b shown in FIG. 6A denote antinode positions of the second-order bending vibration mode.

  Further, at the node position 121a, the node position 121b, and the node position 121c of the diaphragm 102, the vibration in the Z direction due to the secondary bending vibration mode is very small. Since the contact portion 102b of the diaphragm 102 described above is provided at the node position 121a and the node position 121b, it does not vibrate in the Z direction due to the secondary bending vibration mode, but vibrates in the X direction. By providing the contact portion 102b at such a position, the contact portion 102b is caused to vibrate in the X direction by the secondary bending vibration mode in the X direction. The secondary bending vibration is a feed vibration that vibrates in the driving direction.

  FIG. 6 (B) is a view showing the positions of nodes and antinodes of the primary bending vibration mode in the Y direction. Reference numerals 121 d and 121 e shown in FIG. 6B denote node positions of the primary bending vibration mode. Reference numeral 122 c shown in FIG. 6B is an antinode position of the primary bending vibration mode. In the node position 121d and the node position 121e, the vibration in the Z direction due to the primary bending vibration mode is very small. On the other hand, at the antinode position 122c, the vibration largely in the Z direction by the primary bending vibration mode. Since the contact portion 102b described above is provided at the antinode position 122c, it does not vibrate in the X direction by the primary bending vibration mode, but vibrates in the Z direction. By providing the contact portion 102b at such a position, vibration in the Z direction is generated in the contact portion 102b by the primary bending vibration mode in the Y direction. The primary bending vibration is a push-up vibration in which the contact portion of the vibrator vibrates in the pressing direction.

  The vibrator 109 of the ultrasonic motor according to the present embodiment generates elliptical vibration in the contact portion 102b of the diaphragm 102 by combining the two orthogonal bending vibration modes described above.

  Next, the magnitudes of strain in two bending vibration modes will be described with reference to FIGS. 7 (A) and 7 (B). FIG. 7A is a graph showing strain in the X direction at each position in the X direction in the second-order bending vibration mode. The horizontal axis of the graph shown in FIG. 7A is the position in the X direction, and the vertical axis is the distortion in the X direction. The strain in the X direction reaches the maximum value Str1 at the belly position 122a in the bending vibration mode at the position in the X direction of the second order, and at the belly position 122b in the bending vibration mode at the position in the X direction is the second value in the bending direction The value is -Str1. Since the midpoint 121b between the antinode position 122a and the antinode position 122b is a node position, the distortion is zero. Further, since the longitudinal protruding portion 102e is also a free end, the distortion is zero.

  FIG. 7B is a graph showing strain in the Y direction at each position in the Y direction in the primary bending vibration mode. In FIG. 7B, the horizontal axis represents the position in the Y direction, and the vertical axis represents the distortion in the Y direction. The strain in the Y direction becomes the maximum value Str 2 at the antinode position 122 c in the first bending vibration mode at the position in the Y direction. In FIG. 7B, since the longitudinal protruding portion 102e extends over the entire region, it includes a portion where a strain occurs due to the primary bending vibration mode.

  Here, with reference to FIG. 6, a description will be given of suppressing the increase of the first bending vibration without affecting the second bending vibration. First, in FIG. 6A, since the piezoelectric element 103 is not joined to the protruding part 102e in the longitudinal direction, no bending force is generated due to the expansion / contraction difference with the piezoelectric element 103. However, since the longitudinal protrusion 102e is located at the free end of the secondary bending vibration mode, distortion due to the secondary bending vibration mode does not occur as described in FIG. 7A. Therefore, although the longitudinal protruding portion 102e is not joined to the piezoelectric element 103, the amplitude of the secondary bending vibration mode is not suppressed by the longitudinal protruding portion 102e.

  In FIG. 6B, since the piezoelectric element 103 is not joined to the protruding part 102e in the longitudinal direction, no bending force is generated due to the expansion / contraction difference with the piezoelectric element 103. Further, since the longitudinal protruding portion 102e extends over the entire area of the primary bending vibration mode, it includes a portion where a strain due to the primary bending vibration mode is generated as described in FIG. 7 (B). Therefore, the longitudinal protrusion 102e is not joined to the piezoelectric element 103, and the amplitude of the primary bending vibration mode is suppressed by the longitudinal protrusion 102e. As described above, the longitudinal protruding portion 102 e does not affect the amplitude of the secondary bending vibration mode, and can suppress the vibration amplitude only in the primary bending vibration mode.

  Next, referring to FIG. 11, the frequency of the AC voltage applied to the piezoelectric element 103 and the amplitude of the elliptical vibration generated in the contact portion 102b of the diaphragm 102 in the vibrator of the conventional ultrasonic motor and Z in the X direction. The relationship of the amplitude of direction is explained. FIG. 11A shows X-direction amplitude and Z-direction amplitude of elliptical vibration generated at the contact portion 102 b of the diaphragm 102 in accordance with the frequency of the AC voltage applied to the piezoelectric element 103 in the vibrator of the conventional ultrasonic motor. It is the graph which showed a mode that the amplitude of the direction was changing. FIG. 11 (B) is a diagram showing an elliptical vibration locus generated at each frequency of the conventional ultrasonic motor and an elliptical vibration locus at a minimum necessary amplitude in the Z direction.

In FIG. 11A, the horizontal axis represents the frequency f of the AC voltage applied to the piezoelectric element 103, and the vertical axis represents the vibration amplitude. H (f) is the amplitude in the X direction of the elliptical vibration generated at the contact portion 102b of the diaphragm 102, V ₂ (f) is the amplitude in the Z direction of the elliptical vibration generated at the contact portion 102b of the diaphragm 102, V ₀ (f) f) is the minimum necessary amplitude in the Z direction with respect to the amplitude H (f) in the X direction. As it sweeps from the frequency f high frequency f ₁ of the AC voltage applied to the piezoelectric element 103 to a lower frequency f _3, X-direction amplitude H (f) is also the Z-direction amplitude V ₂ (f) is also increased.

In particular, the amplitude V ₂ (f) in the Z direction is larger than the amplitude H (f) in the X direction. This is because the amplitude in the Z direction generated at the contact portion 102b of the diaphragm 102 is generated by the primary bending vibration mode of the vibrator 109, while the vibration in the X direction is the secondary bending vibration mode of the vibrator 109. It is caused by Therefore, the first order bending vibration mode having a smaller order is more likely to be deformed and to have a large amplitude.

On the other hand, since the vibration in the Z direction is the vibration for switching the contact state and the non-contact state of the contact portion 102b of the diaphragm 102, even if it vibrates with an amplitude larger than necessary, it does not lead to an increase in speed, wasting power. It only consumes Therefore, for the amplitude H (f) in the X direction, the minimum required amplitude V ₀ (f) in the Z direction is smaller than the amplitude H (f) in the X direction.

FIG. 11B shows an elliptical vibration locus (Generated Elliptic Oscillation) generated at the high frequency f ₁ , the intermediate frequency f ₂ and the low frequency f ₃ of the conventional ultrasonic motor and an ellipse at the minimum necessary amplitude in the Z direction. It is a figure showing a vibration locus. The Elliptic Vibration Trajectory (Minimal Elliptic Oscillation) at the minimum necessary amplitude in the Z direction does not become so long an ellipse even if the frequency f sweeps from the high frequency f ₁ to the low frequency f ₃ . On the other hand, when the frequency f sweeps from the high frequency f ₁ to the low frequency f ₃ , the elliptical vibration locus that is generated becomes a very long ellipse, and the amplitude in the Z direction becomes larger than necessary.

As described above, in the conventional ultrasonic motor, the amplitude in the Z direction may be smaller than the amplitude in the X direction, but the amplitude V ₂ (f) in the Z direction is larger than necessary and consumes unnecessary power. As a result, the driving efficiency of the ultrasonic motor is reduced.

  Next, FIG. 8A shows X of the elliptical vibration generated at the contact portion 102b of the diaphragm 102 in accordance with the frequency of the AC voltage applied to the piezoelectric element 103 in the vibrator of the ultrasonic motor according to the present embodiment. It is the graph in which the amplitude of the direction and the amplitude of the Z direction showed change. FIG. 8B is a diagram showing an elliptical vibration locus generated at each frequency of the ultrasonic motor of the present embodiment and an elliptical vibration locus at a minimum necessary amplitude in the Z direction.

In FIG. 8A, the horizontal axis represents the frequency f of the AC voltage applied to the piezoelectric element 103, and the vertical axis represents the vibration amplitude. H (f) is the amplitude in the X direction of the elliptical vibration generated at the contact portion 102b of the diaphragm 102, V (f) is the amplitude in the Z direction of the elliptical vibration generated at the contact portion 102b of the diaphragm 102, V ₀ (f ) Is the minimum necessary amplitude in the Z direction with respect to the amplitude H (f) in the X direction. In the ultrasonic motor according to the present embodiment, by providing the protruding portion 102e in the longitudinal direction as described with reference to FIG. 6, the amplitude of the secondary bending vibration mode is not affected, and only the primary bending vibration mode has an amplitude. The configuration is to suppress. Therefore, the amplitude V (f) in the Z direction can be suppressed to be smaller than the amplitude H (f) in the X direction. As a result, the amplitude V (f) in the Z direction can be made closer to the minimum required amplitude V ₀ (f) in the Z direction, and a reduction in drive efficiency can be reduced.

FIG. 8B shows the elliptical vibration locus generated at high frequency f ₁ , intermediate frequency f ₂ and low frequency f ₃ and the elliptical vibration locus at the minimum necessary Z-direction amplitude in the ultrasonic motor of this embodiment. FIG. Even if the frequency f sweeps from the high frequency f ₁ to the low frequency f ₃ , the amplitude V (f) of the generated elliptical vibration locus in the Y direction is the Z direction of the elliptic vibration locus at the minimum necessary Z amplitude. The shape is substantially the same as the amplitude V ₀ (f) of Therefore, unnecessary power is not consumed by oscillating in the Z direction more than necessary.

  As described above, in the ultrasonic motor of the present embodiment, by providing the protruding portion 102e in the longitudinal direction, the amplitude of the secondary bending vibration mode is not affected, and the vibration amplitude is suppressed only in the primary bending vibration mode. be able to. As a result, it is possible to reduce power consumption by oscillating in the Z direction more than necessary, and to reduce the driving efficiency of the ultrasonic motor.

  Next, FIG. 9 is a view of the flexible substrate 140 of the ultrasonic motor of the present embodiment as viewed from the + Z direction. 121 b is a node position of the second order bending vibration mode. 122c is an antinode position of the primary bending vibration mode. The first copper foil 140 a is electrically connected to the first electrode area 103 a of the piezoelectric element 103. The second copper foil 140 b is electrically connected to the second electrode region 103 b of the piezoelectric element 103. The GND copper foil 140 c is electrically connected to the GND electrode area 103 c of the piezoelectric element 103. Further, only the portion of the GND copper foil 140c is shaped so that the coverlay region 140e is cut out.

  In the flexible substrate 140, copper foil is more rigid than the base material. The copper foil 140a, the copper foil 140b, and the copper foil 140c of the flexible substrate 140 of the ultrasonic motor according to the present embodiment are divided into three in the longitudinal direction (X direction) and not in the lateral direction (Y direction) . As a result, the flexible substrate 140 is weak in rigidity in the longitudinal direction (X direction) and easily bent, and high in rigidity in the short direction (Y direction).

  Next, FIG. 10 is a view of a state in which the flexible substrate 140 is attached to the vibrator 109 of the ultrasonic motor of the present embodiment as viewed from the + Z direction. The flexible substrate 140 is disposed on the vibrator 109 so as to be centered in the X direction, and is disposed in the Y direction so that the GND electrode 103 c side of the piezoelectric element 103 is in the drawing direction of the flexible substrate 140. The first copper foil 140a is the first electrode region 103a of the piezoelectric element 103, the second copper foil 140b is the second electrode region 103b of the piezoelectric element 103, and the third copper foil 140c is the GND of the piezoelectric element 103. It bonds so that it may conduct | electrically_connect with the electrode area | region 103c.

  The copper foil 140a, the copper foil 140b, and the copper foil 140c of the flexible substrate 140 of the ultrasonic motor according to this embodiment are divided into three in the longitudinal direction (X direction), and are divided in the lateral direction (Y direction) Not. Therefore, the rigidity is weak and easy to bend for the secondary bending vibration in the longitudinal direction of the vibrator 109, and the rigidity is strong for the primary bending vibration in the short direction and hard to bend. As a result, the amplitude of the second-order bending vibration mode can be suppressed without affecting the amplitude of the second-order bending vibration mode. With the configuration as described above, it is possible to reduce unnecessary driving power by oscillating in the Y direction more than necessary and consuming unnecessary power.

  As described above, the vibration plate 102 protrudes over the entire circumference with respect to the piezoelectric element 103, and the amount of protrusion in the longitudinal direction (X direction) is larger than that in the short direction (Y direction). It is possible to realize an ultrasonic motor with reduced efficiency drop.

  As mentioned above, although the preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

101 Friction member 102 Diaphragm 102 e Longitudinal protruding portion 103 Piezoelectric element 109 Vibrator

Claims (7)

The vibrator is provided with a piezoelectric element attached to a vibrating plate having a sliding portion, and the sliding portion is frictionally contacted with the sliding portion by elliptical vibration due to a plurality of orthogonal vibrations excited by the piezoelectric element. A vibrating member in which the vibrator and the vibrator move relative to each other,
The diaphragm in the longitudinal direction and the transverse direction, have a protruding portion with respect to the piezoelectric element,
In the protruding portion, the amount of protruding in the longitudinal direction is larger than the amount of protruding in the lateral direction,
A flexible substrate is attached to the piezoelectric element such that the drawing direction is parallel to the short direction,
A copper foil provided on the flexible substrate electrically connected to an electrode of the piezoelectric element is divided into a plurality of parts in the longitudinal direction, and connected in the lateral direction . The vibration type actuator according to claim 1 , wherein the plurality of orthogonal vibrations are primary bending vibration in which the sliding portion vibrates in a pressing direction and secondary bending vibration in a driving direction. . The vibration type actuator according to claim 2 , wherein the longitudinal protruding portion is a free end in the second-order bending vibration. The vibration type actuator according to claim 2 or 3 , wherein the sliding portion is provided at a position of an antinode in the first bending vibration and a position of a node in the second bending vibration. The diaphragm includes a rectangular portion to which the piezoelectric element is attached, a support portion supported by a support member, and an arm portion connecting the rectangular portion and the support portion.
The vibration type actuator according to any one of claims 1 to 4 , wherein a protruding portion is provided in the rectangular portion. The said vibrator | oscillator ultrasonically vibrates by the application of a voltage, The ultrasonic motor which functions as a vibration-type actuator of any one of the Claims 1-5 characterized by the above-mentioned. A lens barrel using the vibration-type actuator according to any one of claims 1 to 5 as a drive actuator.

Images