JP5153185B2 - Vibration wave driving device and vibrator - Google Patents

Description

  The present invention is driven by utilizing the frictional force generated between the vibrating body and the vibration body such as an ultrasonic motor used as a driving source in a camera lens or an electrophotographic apparatus. The present invention relates to a vibration wave driving device for driving a body and a vibrator used in the vibration wave driving device.

  As an example of an ultrasonic motor that is one of vibration wave driving devices, for example, there is a configuration disclosed in Patent Document 1. The vibrating body disclosed here is composed of a cylindrical electro-mechanical energy conversion element provided with electrodes and an elastic member such as a cylindrical metal, and the electro-mechanical energy conversion element is sandwiched by elastic members from both sides. It is fixed by doing.

  A shaft rod, which is a shaft for fixing the vibrating body, is disposed in the through hole at the center of the vibrating body. The shaft rod also has a function of determining a rotation center position of a contact body that is a rotor driven by a traveling wave generated on the surface of the vibrating body.

  In addition, a screw is formed on the outer peripheral portion of the shaft rod, and the vibrating body is fixed by engaging with a screw formed on the inner peripheral portion of one elastic body sandwiching the electro-mechanical energy conversion element. To do.

Further, Patent Document 2 discloses a configuration in which only an electro-mechanical energy conversion element provided with an electrode is used without using an elastic member for a vibrating body. Here, an attempt is made to stabilize the vibrator performance and reduce the cost by eliminating the presence of the interface between the electromechanical energy conversion element and the elastic member.
Japanese Patent Laid-Open No. 11-235058 JP 2001-37270 A

  As described above, when the vibrating body is constituted by an electro-mechanical energy conversion element without using an elastic member, there has been proposed a method of supporting the inner peripheral portion of the electro-mechanical energy conversion element and the shaft rod in combination. ing.

  However, the diameter (inner diameter) of the inner periphery of the electro-mechanical energy conversion element made by sintering varies considerably, and post-processing is required to achieve dimensional accuracy in order to connect by fitting or the like. This leads to an increase in cost.

  In addition, if the shaft rod is forcibly pressed into the electromechanical energy conversion element, the electromechanical energy conversion element is broken. Furthermore, when an electromechanical energy conversion element that does not have a dimensional accuracy of the inner diameter and an axial rod are to be adhesively bonded, the variation in the gap leads to the variation in the amount of adhesive, and the vibration transmission loss is large to small. Will occur, leading to instability of the vibrator performance.

  An object of the present invention is to provide a vibration wave driving device and a vibrator that are inexpensive and have small individual differences.

In order to achieve the above object, a vibration wave driving device of the present invention includes a vibrator having a cylindrical electro-mechanical energy conversion element and a shaft rod disposed inside the electro-mechanical energy conversion element, The electro-mechanical energy conversion element is supported by the shaft rod via a connecting portion, and an AC signal is supplied to the electro-mechanical energy conversion element, whereby the vibration in the vibration wave driving apparatus which child drives the front SL contact body, the electric - by the AC signal is supplied to the mechanical energy conversion element, the electrical - the mechanical energy conversion element, around the axle bending vibration occurs, the coupling portion, the electrical - than mechanical energy conversion element and shaft rod, the amount of elastic deformation for the same amount of force is large shape or material Formed of an elastic member, and the electric in the direction of the shaft rod in a state of being elastically deformed - characterized in that it supports the position other than the end portion of the mechanical energy conversion element in the axle.

In order to achieve the above object, a vibrator according to the present invention includes a cylindrical electro-mechanical energy conversion element, a shaft rod disposed inside the electro-mechanical energy conversion element, and the electro-mechanical energy conversion element. In the vibrator having a connecting portion that supports the shaft rod, an AC signal is supplied to the electro-mechanical energy conversion element so that the electro-mechanical energy conversion element is centered on the shaft rod. Bending vibration is generated, and the connecting portion is made of an elastic member having a shape or material in which the amount of elastic deformation with respect to the same magnitude of force is larger than that of the electromechanical energy conversion element and the shaft rod, and is elastic. The shaft rod is fixed to a position other than the end of the electro-mechanical energy conversion element in the direction of the shaft rod in a deformed state.

In the vibration wave driving device of the present invention, the connecting portion for supporting the electro-mechanical energy conversion element on the shaft rod has a larger amount of elastic deformation with respect to the same magnitude of force than the electro-mechanical energy conversion element and the shaft rod. It is comprised with the elastic member of the shape or material which becomes. Then, the electromechanical energy conversion element is supported on the shaft rod in an elastically deformed state.

  With this structure, it is possible to provide a vibration wave driving device and a vibrator that are inexpensive and have small individual differences.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a configuration diagram of a vibration wave driving device according to a first embodiment of the present invention.

  In the vibration wave driving device of FIG. 1, the cylindrical piezoelectric element 101 functions as an electro-mechanical energy conversion element. A shaft rod 102 is disposed inside a through hole at the center of the cylindrical piezoelectric element 101.

  The shaft rod 102 is coupled to the inner peripheral portion of the cylindrical piezoelectric element 101 via a connecting portion 103 made of an elastic member. A vibrator 104 is formed by the cylindrical piezoelectric element 101, the shaft rod 102, and the connecting portion 103. The connecting portion 103 is constituted by a projecting member having a spring property formed integrally with the shaft rod 102.

  The connecting portion 103 is formed of a shape or material that increases the amount of elastic deformation with respect to the same magnitude of force in the radial direction of the cylindrical piezoelectric element 101 as compared to the cylindrical piezoelectric element 101 and the shaft rod 102. Yes.

  By inserting the shaft rod 102 integrally formed with the connecting portion 103 into the through hole of the cylindrical piezoelectric element 101, the connecting portion 103 is elastically deformed by being pushed by the inner peripheral portion of the cylindrical piezoelectric element 101. To do.

  When the restoring force against the elastic deformation of the connecting portion 103 also acts in the radial direction of the cylindrical piezoelectric element 101, the shaft rod 102 is held inside the through hole of the cylindrical piezoelectric element 101, and the cylindrical piezoelectric element 101 and The relative position with respect to the shaft rod 102 is fixed.

  The shaft rod 102 is fixed to a pedestal 105 that fixes the vibration wave driving device itself, and the shaft 104 supports the vibrator 104 so that the vibrator 104 is fixed to the pedestal 105.

  In this manner, the shaft rod 102 can be easily coupled to the inner peripheral portion of the sintered cylindrical piezoelectric element 101 having a variation in dimensional accuracy through the connecting portion 103 that is elastically deformed.

  Furthermore, since the vibration excited by the cylindrical piezoelectric element 101 can be absorbed by the elastically deforming connecting portion 103, the shaft rod 102 is coupled to the cylindrical piezoelectric element 101 at a location away from the vibration node. Nevertheless, the overall support loss of the vibrator 104 can be reduced.

  FIG. 2 is a diagram showing various shapes of the connecting portion in FIG.

  The connecting portion 103 in FIG. 3A is constituted by a plurality of leaf springs extending radially outward around the shaft rod 102.

  The connecting portion 103 in FIG. 5B is configured by a disc spring extending outward around the shaft rod 102.

  The connecting portion 103 in FIG. 5C is formed by forming a slit 102a at the end of the hollow shaft 102 and expanding the portion sandwiched between the two slits 102a outward.

  The connecting portion 103 may have a bellows shape or the like as long as it has a spring property. In addition, use of a shape memory alloy, a heat shrinkable tube, a resin, a sponge, or the like as a material having a spring property may be considered, and these may be used.

  When the shaft rod 102 and the connecting portion 103 are integrally manufactured, in the case of resin or the like, a highly accurate part can be manufactured by manufacturing by injection molding.

  Returning to FIG. 1, the flexible substrate 106 is used to supply electric energy to the vibrator 104 to generate vibrations or to extract charges to the outside for detection of vibrations generated by the vibrator 104.

  The contact body 107 is in contact with the upper end portion of the vibrator 104 via a contact spring 108 and is rotationally driven by the combined vibration of the vibrator 104. The contact spring 108 is in direct contact with the vibrator 104. The output gear 109 supports the contact body 107 so as to be rotatable with respect to the shaft rod 102.

  The coil spring 110 is a spring member that urges the contact body 107 downward and presses it against the vibrator 104, and enables frictional contact between the vibrator 104 and the contact body 107. By adjusting the applied pressure between the vibrator 104 and the contact body 107 by the coil spring 110, the output torque of the vibration wave driving device can be adjusted.

  The connecting portion 103 may be formed as a male screw on the surface of the shaft rod 102, and the connecting portion 103, which is the male screw, may be used as a self-tap to couple the shaft rod 102 and the vibrator 104. Since coupling is performed as a self-tap, variation in accuracy of the inner diameter dimension of the cylindrical piezoelectric element 101 can be allowed, and both can be easily coupled.

  3A and 3B are configuration diagrams of the cylindrical piezoelectric element in FIG. 1, where FIG. 3A is an external view, and FIG. 3B is a cross-sectional view taken along line AA ′ of FIG.

  An inner peripheral electrode 301 is formed on the entire inner peripheral portion of the cylindrical piezoelectric element 101, and outer peripheral electrodes 302, 303, 304, and 305 that are divided into four in the circumferential direction are parallel to the axial direction on the outer peripheral portion. Is formed.

  All of the electrodes extend to the inside of the bottom surface of the cylindrical piezoelectric element 101, and an electric signal (AC signal) for driving is supplied from the flexible substrate 106 therefrom. Note that the arrow in (b) indicates the polarization direction of the cylindrical piezoelectric element 101.

  At the time of driving, the inner peripheral electrode 301 is dropped to the ground, a two-phase AC electric field is applied to the outer peripheral electrodes 302 to 305, and two sets of bending vibrations having different time phases are excited.

  Specifically, the cylindrical piezoelectric element 101 includes a bending vibration that occurs in the direction of the outer peripheral electrode 302 and the outer peripheral electrode 305 around the shaft rod 102, and an outer peripheral electrode 303 and an outer peripheral electrode 304 that are 90 degrees different in spatial phase. The bending vibration generated in the direction of is generated by shifting the time phase.

  As a result, a synthetic vibration is generated in the cylindrical piezoelectric element 101 (vibrator 104), and the cylindrical piezoelectric element 101 moves in a circle or an ellipse around the shaft rod 102.

  Here, sin (ωt) and cos (ωt) in FIG. 3B indicate the temporal phase relationship of the AC electric field to be applied. When an alternating electric field of Va · sin (ωt) is applied to the outer peripheral electrodes 302 and 305, the direction of polarization is reversed. Therefore, when the outer peripheral electrode 32 portion extends in the axial direction due to the piezoelectric lateral effect, the outer peripheral electrode 305 portion contracts and vibrates. The entire child undergoes bending vibration. The same bending vibration is also performed between the peripheral electrodes 303 and 304 at different time phases of the applied electric field by 90 degrees.

  FIG. 4 is a main part configuration diagram of the vibration wave driving device according to the second embodiment of the present invention.

  In FIG. 4, a shaft rod 102 penetrating the center hole of a cylindrical piezoelectric element 101 as a vibrating body is coupled to the cylindrical piezoelectric element 101 via connecting portions 103a and 103b. The vibrator 104 is formed by the cylindrical cylindrical piezoelectric element 101, the shaft rod 102, and the connecting portions 103a and 103b.

  The connecting portions 103a and 103b having a spring property formed integrally with the shaft rod 102 are directed in opposite directions, and the support of the shaft rod 102 can be stabilized. Needless to say, the connecting portions 103a and 103b may be provided at a plurality of positions in the axial direction. Needless to say, the projecting positions of the connecting portions 103a and 103b facing in opposite directions on the shaft rod 102 are not the same position and can be set to arbitrary positions.

  FIG. 5 is a main part configuration diagram of a vibration wave driving device according to a third embodiment of the present invention.

  In FIG. 5, a shaft rod 102 penetrating the center hole of a cylindrical piezoelectric element 101 as a vibrating body is coupled to the cylindrical piezoelectric element 101 via connecting portions 103a and 103c. The vibrator 104 is formed by the cylindrical cylindrical piezoelectric element 101, the shaft rod 102, and the connecting portions 103a and 103c.

  The connecting portions 103a and 103c having a spring property formed integrally with the shaft rod 102 are oriented in the same direction, so that the support of the shaft rod 102 can be stabilized and the vibrator 104 is connected to the contact body. It can also function as a spring member that presses against 107. Needless to say, the connecting portions 103a and 103b may be provided at a plurality of positions in the axial direction. Needless to say, the number of connecting portions 103a and 103c can also be set at an arbitrary position.

  FIG. 6 is a main part configuration diagram of a vibration wave driving device according to a fourth embodiment of the present invention.

  In FIG. 6, a shaft rod 102 that passes through the center hole of a cylindrical piezoelectric element 101 as a vibrating body is coupled to the cylindrical piezoelectric element 101 via a connecting portion 103. The cylindrical piezoelectric element 101, the shaft rod 102, and the connecting portion 103 form a vibrator 104.

  Here, the connecting portion 103 having a spring property formed integrally with the shaft rod 102 is set so that its rigidity is non-uniform in the XY direction on the paper surface.

  In FIG. 2A, the connecting portion 103 made of a leaf spring is arranged so as to have nonuniform rigidity in the XY direction. In FIG. 7B, the notch 103d is provided in the connecting part 103 made of a disc spring, so that the rigidity becomes nonuniform in the XY direction.

  In the present embodiment, since the two natural frequencies in the XY directions are positively different from each other, there is no solution of a frequency having a phase difference of 90 degrees and a large value for both amplitudes. Vibration that causes traveling waves, that is, squealing is less likely to occur, and stable driving is possible. Further, in order to make the shape non-uniform, a member such as an E ring may be applied to the shaft rod 102.

It is a block diagram of the vibration wave drive device which concerns on the 1st Embodiment of this invention. It is a figure which shows the various shapes of the connection part in FIG. It is a block diagram of the cylindrical piezoelectric element in FIG. It is a principal part block diagram of the vibration wave drive device which concerns on the 2nd Embodiment of this invention. It is a principal part block diagram of the vibration wave drive device which concerns on the 3rd Embodiment of this invention. It is a principal part block diagram of the vibration wave drive device which concerns on the 4th Embodiment of this invention.

Explanation of symbols

101 Cylindrical piezoelectric element (electro-mechanical energy conversion element)
102 Shaft rod 103 Connecting part (overhang member)
104 vibrator 105 pedestal 106 flexible substrate 107 contact body 108 contact spring 109 output gear 110 coil spring

Claims (4)

A vibrator having a cylindrical electro-mechanical energy conversion element and a shaft rod disposed inside the electro-mechanical energy conversion element, and a contact body in contact with the vibrator, the electro-mechanical energy conversion element is supported by the axle through a connecting portion, the electric - by AC signal into mechanical energy conversion element is supplied, in the vibration wave driving apparatus in which the vibrator drives the front SL contact body,
By supplying the AC signal to the electro-mechanical energy conversion element, the electro-mechanical energy conversion element is subjected to bending vibration about the shaft rod,
The connecting portion, the electric - than mechanical energy conversion element and shaft rod, formed of an elastic material having the same size of the shape or material in the amount of elastic deformation increases to a force, and said in an elastically deformed state A vibration wave driving device characterized in that a position other than the end of the electro-mechanical energy conversion element in the direction of the shaft rod is supported by the shaft rod. In a vibrator comprising a cylindrical electro-mechanical energy conversion element, a shaft rod disposed inside the electro-mechanical energy conversion device, and a connecting portion that supports the electro-mechanical energy conversion device on the shaft rod. ,
By supplying an AC signal to the electro-mechanical energy conversion element, the electro-mechanical energy conversion element undergoes bending vibration about the shaft rod,
The connecting portion, the electric - than mechanical energy conversion element and shaft rod, formed of an elastic material having the same size of the shape or material in the amount of elastic deformation increases to a force, and said in an elastically deformed state A vibrator characterized by fixing the shaft rod to a position other than the end of the electro-mechanical energy conversion element in the direction of the shaft rod.   The connecting portion is constituted by at least a plurality of leaf springs extending radially outward around the shaft rod, or is constituted by a disc spring extending outward around the shaft rod, or 2. A vibration wave driving device according to claim 1, wherein a slit is formed at an end of the hollow shaft rod, and a portion sandwiched between the two slits is expanded outward.   The connecting portion is constituted by at least a plurality of leaf springs extending radially outward around the shaft rod, or is constituted by a disc spring extending outward around the shaft rod, or 3. The vibrator according to claim 2, wherein a slit is formed at an end of the hollow shaft rod, and a portion sandwiched between the two slits is expanded outward.

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