WO2010140619A1 - 振動アクチュエータ、レンズ鏡筒及びカメラ - Google Patents
振動アクチュエータ、レンズ鏡筒及びカメラ Download PDFInfo
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- WO2010140619A1 WO2010140619A1 PCT/JP2010/059348 JP2010059348W WO2010140619A1 WO 2010140619 A1 WO2010140619 A1 WO 2010140619A1 JP 2010059348 W JP2010059348 W JP 2010059348W WO 2010140619 A1 WO2010140619 A1 WO 2010140619A1
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- Prior art keywords
- vibration actuator
- piezoelectric body
- actuator according
- vibration
- vibrator
- Prior art date
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- 230000005284 excitation Effects 0.000 claims abstract description 3
- 230000002093 peripheral effect Effects 0.000 claims description 16
- 244000126211 Hericium coralloides Species 0.000 description 7
- 229920001971 elastomer Polymers 0.000 description 6
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- 238000003384 imaging method Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- OFNHPGDEEMZPFG-UHFFFAOYSA-N phosphanylidynenickel Chemical compound [P].[Ni] OFNHPGDEEMZPFG-UHFFFAOYSA-N 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
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- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229920005549 butyl rubber Polymers 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
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- 238000007906 compression Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000007772 electroless plating Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
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Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- H02N2/00—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction
- H02N2/10—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors
- H02N2/16—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing rotary motion, e.g. rotary motors using travelling waves, i.e. Rayleigh surface waves
- H02N2/163—Motors with ring stator
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/02—Mountings, adjusting means, or light-tight connections, for optical elements for lenses
- G02B7/04—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification
- G02B7/08—Mountings, adjusting means, or light-tight connections, for optical elements for lenses with mechanism for focusing or varying magnification adapted to co-operate with a remote control mechanism
Definitions
- the present invention relates to a vibration actuator, a lens barrel including the vibration actuator, and a camera.
- the vibration actuator generates a progressive vibration wave on the driving surface of the elastic body by utilizing the expansion and contraction of the piezoelectric body.
- This traveling wave causes an elliptical motion on the driving surface and adds to the wavefront of the elliptical motion.
- the moving element in pressure contact is driven (see Patent Document 1).
- Such a vibration actuator is characterized by having a high torque even at a low rotation. For this reason, when mounted on the drive device, there is an advantage that the gear of the drive device can be omitted, gear noise can be eliminated, and positioning accuracy can be improved.
- the space for placing vibration actuators has also been limited.
- the vibration actuator is reduced in size as a whole in accordance with the space, the diameter of the vibrator is shortened, so that the generated torque tends to decrease.
- An object of the present invention is to provide a vibration actuator that can be arranged in a limited space and has good driving performance, and a lens barrel and a camera including the vibration actuator.
- the present invention solves the above problems by the following means.
- the invention according to claim 1 includes a piezoelectric body having a first surface and excited by an electric signal, and a second surface bonded to the first surface and generating a vibration wave by the excitation. And a moving body that is in pressure contact with the second surface and moves relative to the vibrating body, and the thickness of the piezoelectric body is different along the relative movement direction of the moving body.
- This is a vibration actuator characterized by the above.
- a second aspect of the present invention is the vibration actuator according to the first aspect, wherein the piezoelectric body is divided into a third surface opposite to the first surface along the relative movement direction.
- the piezoelectric actuator has a plurality of electrode portions, and the piezoelectric body has a constant thickness in a region where the same electrode portions are formed.
- a third aspect of the present invention is the vibration actuator according to the first or second aspect, wherein the piezoelectric body includes an inner peripheral portion provided with a circular opening, an elliptical shape, The vibration actuator has an outer peripheral portion, and the piezoelectric body is thicker on the major axis side of the ellipse than on the minor axis side.
- a fourth aspect of the present invention is the vibration actuator according to the third aspect, wherein the circumferential lengths of the plurality of electrode portions on the inner peripheral side are equal to each other. It is.
- the invention according to claim 5 is the vibration actuator according to claim 3 or 4, wherein the relative movement direction of the movable body is a direction along a circumferential direction of the inner circumferential portion of the piezoelectric body.
- a sixth aspect of the present invention is the vibration actuator according to any one of the third to fifth aspects, wherein the movable body has an annular shape, and the inner surface of the piezoelectric body on the second surface. It is a vibration actuator characterized by being provided in contact with a position along the circumferential direction of the peripheral portion.
- a seventh aspect of the present invention is the vibration actuator according to any one of the first to fifth aspects, wherein the second surface side of the vibration body has a plurality of grooves so as to be comb-shaped. Is formed, and the depth of the groove in the direction intersecting the relative movement direction of the moving body is different along the relative movement direction of the moving body.
- the invention according to claim 8 is a lens barrel including the vibration actuator according to any one of claims 1 to 7.
- a ninth aspect of the present invention is a camera comprising the vibration actuator according to any one of the first to seventh aspects.
- a vibration actuator that can be arranged in a limited space and has good driving performance, and a lens barrel and a camera including the vibration actuator.
- FIG. 1 is a diagram illustrating a camera 1 according to a first embodiment of the present invention.
- FIG. 2 is a view of the inside of the lens barrel 3 in the camera 1 as viewed from the subject side.
- the camera 1 includes a camera body 2 having an image sensor 8 and a lens barrel 3 having a lens 7.
- the lens barrel 3 is an interchangeable lens that can be attached to and detached from the camera body 2.
- the lens barrel 3 is an interchangeable lens.
- the present invention is not limited to this.
- the lens barrel 3 may be a lens barrel integrated with the camera body.
- the lens barrel 3 includes a lens 7, a cam barrel 6, gears 4 and 5, an ultrasonic motor 10, and a housing 9 that surrounds them.
- the ultrasonic motor 10 is disposed in an annular gap between the cam cylinder 6 and the housing 9 as shown in FIG.
- the ultrasonic motor 10 is used as a drive source that drives the lens 7 during the focusing operation of the camera 1.
- the driving force obtained from the ultrasonic motor 10 is transmitted to the cam cylinder 6 through the gears 4 and 5.
- the lens 7 is held by the cam barrel 6 and is moved substantially parallel to the optical axis direction (in the direction of arrow L shown in FIG. 1) by the driving force of the ultrasonic motor 10 to adjust the focus. It is.
- a subject image is formed on the imaging surface of the imaging device 8 by a lens group (including the lens 7) (not shown) provided in the lens barrel 3.
- the imaged subject image is converted into an electrical signal by the image sensor 8, and image data is obtained by A / D converting the signal.
- FIG. 3 is a cross-sectional view of the ultrasonic motor 10 of the first embodiment.
- an XYZ orthogonal coordinate system is provided in FIG. 3 and FIGS. 4 to 6 described later.
- the direction parallel to the axial direction of the output shaft 18 was defined as the Z-axis direction, and the direction toward the moving element 15 in the Z-axis direction was defined as the Z-axis plus direction.
- the direction parallel to the major axis (major axis, see FIG. 4) of the outer shape of the vibrator 11 viewed from the Z axis plus direction (moving element 15 side) is the X axis direction and minor axis (minor axis, FIG. 4).
- the direction parallel to the reference) is taken as the Y-axis direction.
- the ultrasonic motor 10 includes a vibrator 11, a mover 15, an output shaft 18, a pressure member 19, and the like, the vibrator 11 side is fixed, and the mover 15 is rotationally driven. Yes.
- the vibrator 11 is a hollow member having an elastic body 12 and a piezoelectric body 13 joined to the elastic body 12.
- the elastic body 12 is a member formed of a metal material having a high resonance sharpness.
- the elastic body 12 has a hollow shape (see FIG. 3A) whose outer shape is substantially elliptical.
- the elastic body 12 includes a comb tooth portion 12a, a base portion 12b, a flange portion 12c, and the like.
- the comb tooth portion 12 a is formed by cutting a plurality of grooves 30 (shown in FIG. 4) on the surface that contacts the moving element 15, and the tip surface of the comb tooth portion 12 a is pressed against the moving element 15.
- the contact surface is a drive surface 12d for driving the moving element 15.
- This drive surface is subjected to a lubricious surface treatment such as Ni-P (nickel-phosphorus) plating.
- Ni-P nickel-phosphorus
- the base portion 12b is a portion that is continuous in the circumferential direction of the elastic body 12, and the piezoelectric body 13 is joined to the surface 12e of the base portion 12b opposite to the comb teeth portion 12a.
- the flange portion 12c is a bowl-shaped portion protruding in the inner diameter direction of the elastic body 12, and is disposed at the center in the thickness direction of the base portion 12b.
- the vibrator 11 is fixed to the fixing member 16 by the flange portion 12c.
- the piezoelectric body 13 is a piezoelectric body that converts electrical energy into mechanical energy.
- a piezoelectric element is used as the piezoelectric body 13, but an electrostrictive element or the like may be used.
- the piezoelectric body 13 will be described in detail later.
- the piezoelectric body 13 is bonded to the elastic body 12 using an adhesive.
- the wiring of the flexible printed circuit board 14 is connected to the electrode portion of the piezoelectric body 13.
- the flexible printed circuit board 14 has a function of supplying a drive signal to the piezoelectric body 13.
- the piezoelectric body 13 is expanded and contracted by the drive signal supplied from the flexible printed circuit board 14 to excite the elastic body 12 and a traveling wave is generated on the drive surface of the elastic body 12. In the present embodiment, four traveling waves are generated.
- the moving element 15 is a member that is rotationally driven by a traveling wave generated on the driving surface of the elastic body 12.
- the mover 15 is a substantially disk-shaped member made of a light metal such as aluminum, and has a contact surface 15a that contacts the vibrator 11 (the drive surface 12d of the elastic body 12).
- the contact surface 15a has a substantially annular shape, and the surface of the contact surface 15a is subjected to a surface treatment such as alumite for improving wear resistance.
- the output shaft 18 is a substantially cylindrical member. One end of the output shaft 18 is in contact with the moving element 15 via the rubber member 23, and is provided so as to rotate integrally with the moving element 15.
- the rubber member 23 is a substantially ring-shaped member made of rubber.
- the rubber member 23 has a function of allowing the mover 15 and the output shaft 18 to rotate integrally with rubber viscoelasticity, and a function of absorbing vibration so as not to transmit vibration from the mover 15 to the output shaft 18.
- butyl rubber, silicon rubber, propylene rubber and the like are used.
- the pressurizing member 19 is a member that generates a pressing force that pressurizes the vibrator 11 and the moving element 15.
- the pressure member 19 is provided between the gear 4 and the bearing receiving member 21.
- the pressure member 19 uses a compression coil spring, but is not limited thereto.
- the gear 4 is inserted so as to fit in the D cut of the output shaft 18, is fixed by a stopper 22 such as an E ring, and is provided so as to be integrated with the output shaft 18 in the rotation direction and the axial direction.
- the gear 4 transmits driving force to the gear 5 (see FIG. 1) by rotating with the rotation of the output shaft 18.
- the bearing receiving member 21 is arranged on the inner diameter side of the bearing 17, and the bearing 17 is arranged on the inner diameter side of the fixed member 16.
- the pressurizing member 19 pressurizes the vibrator 11 toward the moving element 15 in the axial direction of the output shaft 18. With this applied pressure, the moving element 15 comes into pressure contact with the drive surface of the vibrator 11, Driven by rotation.
- a pressure adjusting washer may be provided between the pressure member 19 and the bearing receiving member 21 so that an appropriate pressure for driving the ultrasonic motor 10 can be obtained.
- FIG. 4 is a diagram illustrating the vibrator 11.
- 4A is a view of the vibrator 11 as viewed from the movable element 15 side
- FIG. 4B is a cross-sectional view of the vibrator 11 along an arrow S1-S2 cross section parallel to the XZ plane
- FIG. 4C is a cross-sectional view of the vibrator 11 taken along a cross section indicated by arrows S3-S4 parallel to the YZ plane.
- the shape indicated by the broken line in FIG. 4A is the shape of the contact surface 15a of the moving element 15 in contact with the drive surface 12d, and the contact surface 15a is in contact with the drive surface 12d in the region indicated by the broken line. Touch.
- FIG. 5 is a diagram showing the piezoelectric body 13 of the present embodiment.
- FIG. 5A is a view of the bonding surface 13a of the piezoelectric body 13 with respect to the elastic body 12 as viewed from the elastic body 12 side.
- FIG. 5B is a view of the surface 13b of the piezoelectric body 13 opposite to the bonding surface 13a as viewed from the gear member 20 side.
- the piezoelectric body 13 has an opening 13d at the center and has a substantially flat plate shape having an inner peripheral portion 13r on the opening 13d side and an outer peripheral portion 13R.
- the bonding surface 13 a of the piezoelectric body 13 is a surface bonded to the elastic body 12. As shown in FIG. 5A, an electrode portion D1 is formed on the substantially entire surface of the bonding surface 13a.
- the electrode part D1 is formed using electroless plating. In the present embodiment, the electrode part D1 is a coating layer of electroless nickel phosphorus (Ni—P) plating.
- electrode portions D2 to D5, D6 to D9 to which A-phase and B-phase electrical signals are input As shown in FIG. 5 (b), on the surface 13b of the piezoelectric body 13 opposite to the bonding surface 13a, electrode portions D2 to D5, D6 to D9 to which A-phase and B-phase electrical signals are input, The electrode part D10 which becomes the ground is formed at a predetermined interval in the circumferential direction. Further, a base portion 13c where the base of the piezoelectric body 13 is exposed is formed between the inner and outer peripheral ends of the surface 13b and between the electrode portions D2 to D10.
- the electrode portions D2 to D5 and D6 to D9 are electrode portions for inputting A-phase and B-phase drive signals, respectively, and are arranged so that polarization is alternated in each phase.
- the electrode part D10 is formed between the electrode part D2 and the electrode part D6 so as to be between the A phase (electrode parts D2 to D5) and the B phase (electrode parts D6 to D9).
- the electrode portions D2 to D10 are formed by applying a silver paste by screen printing.
- the vibrator 11 includes an elastic body 12 and a piezoelectric body 13 and has an elliptical outer shape.
- the reason why the outer shape of the vibrator 11 is thus elliptical is as follows.
- the ultrasonic motor 10 is disposed in an annular gap between the cam cylinder 6 and the housing 9.
- the diameter is limited to the width between the cam cylinder 6 and the housing 9, so that the capacitance of the piezoelectric body is also limited. .
- the capacitance increases as the major axis increases. That is, when the conditions such as thickness and dielectric constant are constant, the capacitance of the piezoelectric body is proportional to the area of the region where the piezoelectric body is polarized. This is because the area to be covered can be widened. That is, if the area of the joint surface between the piezoelectric body and the elastic body is increased, a region where the piezoelectric body is polarized can be increased, and the capacitance of the piezoelectric body can be increased. This is because a larger driving force can be obtained.
- the vibrator 11 (piezoelectric body 13) has an elliptical shape, so that a sufficient space cannot be taken in one direction (the Y direction in the present embodiment).
- the cam cylinder 6 It can arrange
- the width l (for example, l8 and l9 in the electrode portions D8 and D9) is constant in order to make the period of the traveling wave constant. If the circumferential width l of the inner peripheral portion 13r of the electrode is constant, the piezoelectric body 13 is elliptical, and the shape and area of each of the electrode portions D2 to D9 are different.
- ⁇ L d 31 ⁇ V ⁇ L / t (1)
- L length
- ⁇ L displacement in the length direction
- V applied voltage
- d 31 d constant of piezoelectric body
- t thickness
- the length in the circumferential direction at the center of each electrode part D2 to D9 (intermediate part between the inner peripheral part 13r and the outer peripheral part 13R) is L
- the length of L depends on whether the ellipse has a major axis a side or minor axis b side. It is different.
- the circumferential length L8 of the electrode portion D8 on the long diameter a side is longer than the length L9 of the electrode portion D9 on the short diameter b side.
- elongation (DELTA) L in the circumferential length L will differ.
- the traveling wave generated by the elastic body 12 causes the relative movement direction ⁇ of the moving element 15 (the direction along the circumferential direction of the inner peripheral portion of the piezoelectric body 13). Does not occur evenly. For this reason, the height of the traveling wave generated on the drive surface 12d of the elastic body 12 is not constant. Then, the moving element 15 comes into contact with the elastic body 12 only where the wave in the traveling wave is high, the contact becomes unstable, and the driving force is not sufficiently transmitted.
- the circumferential length L of each of the electrode portions D2 to D9 varies along the relative movement direction ⁇ of the movable element 15 (depending on the circumferential position). For this reason, the thickness t is changed in proportion to the circumferential length L, and the elliptical shape in which the thickness t is increased and the length L is shortened on the major axis a side of the elliptical shape in which the circumferential length L is increased. On the side of the minor axis b, the thickness t is reduced so that L / t is constant. In the region where the same electrode portion is formed, the thickness is constant.
- this embodiment has the following effects. (1) As described above, the thickness t is increased on the major axis a side of the elliptical shape where the circumferential length L is increased, and the thickness t is decreased on the minor axis b side of the elliptical shape where L is shortened. , L / t is made constant. Thereby, the elongation ⁇ L of the circumferential length L of the piezoelectric body 13 becomes constant. Therefore, the traveling wave in the moving element 15 is uniformly generated in the relative movement direction ⁇ of the moving element 15 (the direction along the circumferential direction of the inner peripheral portion of the piezoelectric body 13), and the traveling wave generated in the driving surface 12d is high. Is constant. Therefore, the contact between the moving element 15 and the vibrator 15 becomes uniform, and a stable and sufficient driving force can be obtained.
- the vibrator 11 (piezoelectric body 13) has an elliptical shape
- the vibrator 11 can be disposed in a limited place where sufficient space cannot be taken in one direction (Y direction in the present embodiment). Can be used to obtain the maximum torque.
- FIG. 6 is a diagram illustrating the vibrator according to the second embodiment.
- the thickness t is increased on the elliptical major axis a side where the circumferential length L is increased, and the elliptical minor axis b side where L is shortened.
- the thickness t is reduced and L / t is constant.
- the difference between the second embodiment and the first embodiment is that the depth of the groove 130 of the comb tooth portion 112a differs depending on whether the elastic body 112 has the major axis a side or the minor axis b side.
- the other points are the same as those in the first embodiment, and the same parts are denoted by the same reference numerals and the description thereof is omitted.
- the outer shape of the vibrator 11 is an elliptical shape.
- the shape of the vibrator 11 pieoelectric body 13 and elastic body 112
- the radial direction of the elastic body 112 is wider on the major axis a side, so that it is smaller than the minor axis b side. Bending rigidity increases. That is, there is a possibility that the bending stiffness differs in the moving direction ⁇ of the moving body, and the vibration amplitude does not occur evenly in the moving direction ⁇ of the moving element 15.
- FIGS. 6B and 6C the depths of the grooves 130 of the comb teeth 112a are made non-uniform. That is, the groove 130 is deep on the long diameter a side, and the groove 130 is shallow on the short diameter b side.
- the solid line indicates the case of the second embodiment, and the dotted line indicates the case where the depth of the groove 130 of the comb tooth portion 112a is constant.
- the solid line in the figure indicates the second embodiment, and the dotted line indicates the case where the depth of the groove 130 of the comb tooth portion 112a is constant.
- the long diameter a side is wide in the radial direction but the groove 130 is deep, and the short diameter b side is narrow in the radial direction but the groove 130 is shallow, and the radial width and the depth of the groove 130 are
- the influences on the rigidity are offset each other, and the difference in rigidity between the major axis a side and the minor axis b side becomes smaller as compared with the comparative example as shown by the solid line in FIG.
- FIG. 8 is a view showing a modified form of the elastic body 32.
- FIG. 8A is a view of the vibrator 31 viewed from the side of the moving element 15 as in FIG. 4A
- FIG. 8B is a vibration in the cross section of the arrow S1-S2 parallel to the XZ plane.
- FIG. 8C is a cross-sectional view of the vibrator 31 taken along an arrow S3-S4 cross section parallel to the YZ plane.
- the outer shape of the elastic body 32 may be a shape obtained by cutting out the upper part of an elliptical cone shape. Also in this case, the thickness t is increased on the elliptical major axis a side where the circumferential length L becomes longer, and the thickness t of the piezoelectric body 33 is changed on the elliptical minor axis b side where L becomes shorter. It is thinned so that L / t is constant. As described above, even when the elastic body 32 has an elliptical cone shape, the amplitude of the traveling wave generated in the elastic body 32 is constant by changing the thickness of the piezoelectric body 33 between the major axis side and the minor axis side of the ellipse. Can be. Contact between the moving element 15 and the vibrator 31 (elastic body 32) becomes uniform, and a stable and sufficient driving force can be obtained.
- the ultrasonic motor using the vibration in the ultrasonic region has been described as an example.
- the present invention is not limited to this.
- the present invention may be applied to a vibration actuator that uses vibration outside the ultrasonic region. .
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Abstract
Description
請求項2に記載の発明は、請求項1に記載の振動アクチュエータであって、前記圧電体は、前記第1の面と反対側の第3の面に、前記相対移動方向に沿って分割されて形成された複数の電極部を有し、前記圧電体は、同一の電極部が形成されている領域では一定の厚さであること、を特徴とする振動アクチュエータである。
請求項3に記載の発明は、請求項1または請求項2のいずれか1項に記載の振動アクチュエータであって、前記圧電体は、円形の開口が設けられた内周部と、楕円形状の外周部を有し、前記圧電体の厚さは、前記楕円形状の長径側の方が短径側より厚いこと、を特徴とする振動アクチュエータである。
請求項4に記載の発明は、請求項3に記載の振動アクチュエータであって、前記複数の電極部の前記内周部側の周方向の長さが、互いに等しいこと、を特徴とする振動アクチュエータである。
請求項5に記載の発明は、請求項3または4に記載の振動アクチュエータであって、前記移動体の前記相対移動方向は、前記圧電体の前記内周部の周方向に沿った方向であること、を特徴とする振動アクチュエータである。
請求項6に記載の発明は、請求項3~5のいずれか1項に記載の振動アクチュエータであって、前記移動体は円環形状であり、前記第2の面の前記圧電体の前記内周部の周方向に沿った位置に接触されて設けられること、を特徴とする振動アクチュエータである。
請求項7に記載の発明は、請求項1~5のいずれか1項に記載の振動アクチュエータであって、前記振動体の前記第2の面側は、櫛歯状となるように複数の溝が形成され、前記移動体の相対移動方向と交差する方向における前記溝の深さは、前記移動体の相対移動方向に沿って異なっていること、を特徴とする振動アクチュエータである。
請求項8に記載の発明は、請求項1から7のいずれか1項に記載の振動アクチュエータを備えるレンズ鏡筒である。
請求項9に記載の発明は、請求項1から7のいずれか1項に記載の振動アクチュエータを備えるカメラである。
以下、図面等を参照して、本発明の第1実施形態について説明する。なお、以下の実施形態は、振動アクチュエータとして、超音波モータを例に説明する。
電極部D1は、無電解めっきを用いて形成される。本実施形態では、電極部D1は、無電解ニッケルリン(Ni-P)めっきの皮膜層である。
電極部D2~D5、D6~D9は、それぞれ、A相、B相の駆動信号を入力する電極部であり、各相において分極が交互となるように配置されている。電極部D10は、A相(電極部D2~D5)とB相(電極部D6~D9)との間となるように、電極部D2と電極部D6との間に形成されている。
電極部D2~D10は、本実施形態では、銀ペーストをスクリーン印刷によって塗布することにより形成されている。
ΔL=d31×V×L/t …式(1)
ここで、L:長さ、ΔL:長さ方向の変位、V:印加電圧、d31:圧電体のd常数、t:厚さ、である。
(1)このように、周方向の長さLが長くなる楕円形状の長径a側において、厚さtを厚くし、Lが短くなる楕円形状の短径b側において、厚さtを薄くし、L/tが一定になるようする。これにより、圧電体13における周方向の長さLの伸びΔLが一定になる。したがって、移動子15における進行波が、移動子15の相対移動方向θ(圧電体13の内周部の周方向に沿った方向)で均等に発生し、駆動面12dにおいて発生する進行波の高さが一定になる。ゆえに、移動子15と振動子15との接触が均等になり、安定し、且つ十分な駆動力を得ることができる。
次に、本発明の第2実施形態について説明する。図6は、第2実施形態の振動子を示す図である。第2実施形態は、第1実施形態と同様に、周方向の長さLが長くなる楕円形状の長径a側において、厚さtを厚くし、Lが短くなる楕円形状の短径b側において、厚さtを薄くし、L/tが一定となるようになっている。第2実施形態と第1実施形態とが異なる点は、櫛歯部112aの溝130の深さが、弾性体112における長径a側か短径b側かによって異なっている点である。それ以外の点については第1実施形態と同様であり、同様の部分には同一の符号を付し、その説明を省略する。
長径a側では径方向に幅が広いが溝130が深く、短径b側は径方向に幅が狭いが溝130が浅くなっている。したがって、径方向の幅と溝130の深さとの、剛性への影響が互いに相殺されて、長径a側と短径b側における剛性の差が小さくなる。
以上、説明した実施形態に限定されることなく、種々の変形や変更が可能である。
(1)上述の実施形態で弾性体12の外形を楕円柱形状としたが、本発明はこれに限定されない。図8は、弾性体32の変形形態を示す図である。なお、上述の実施形態と同様の部分は同一の符号を付す。図8(a)は図4(a)と同様に、振動子31を移動子15側から見た図であり、図8(b)は、XZ平面に平行な矢印S1-S2断面での振動子31の断面図であり、図8(c)は、YZ平面に平行な矢印S3-S4断面での振動子31の断面図である。
なお、上述の実施形態及び変形形態は、適宜組み合わせて用いることもできるが、詳細な説明は省略する。また、本発明は以上説明した各実施形態によって限定されることはない。
Claims (9)
- 第1の面を有し、電気信号により励振される圧電体と、
前記第1の面に接合され前記励振によって振動波を生じる第2の面を有する振動体と、
前記第2の面に加圧接触され、前記振動体に対して相対移動する移動体とを有し、
前記圧電体の厚さが、前記移動体の相対移動方向に沿って異なっていること、を特徴とする振動アクチュエータ。 - 請求項1に記載の振動アクチュエータであって、
前記圧電体は、前記第1の面と反対側の第3の面に、前記相対移動方向に沿って分割されて形成された複数の電極部を有し、
前記圧電体は、同一の電極部が形成されている領域では一定の厚さであること、を特徴とする振動アクチュエータ。 - 請求項1または請求項2のいずれか1項に記載の振動アクチュエータであって、
前記圧電体は、円形の開口が設けられた内周部と、楕円形状の外周部を有し、
前記圧電体の厚さは、前記楕円形状の長径側の方が短径側より厚いこと、
を特徴とする振動アクチュエータ。 - 請求項3に記載の振動アクチュエータであって、
前記複数の電極部の前記内周部側の周方向の長さが、互いに等しいこと、を特徴とする振動アクチュエータ。 - 請求項3または4に記載の振動アクチュエータであって、
前記移動体の前記相対移動方向は、前記圧電体の前記内周部の周方向に沿った方向であること、を特徴とする振動アクチュエータ。 - 請求項3~5のいずれか1項に記載の振動アクチュエータであって、
前記移動体は円環形状であり、前記第2の面の前記圧電体の前記内周部の周方向に沿った位置に接触されて設けられること、を特徴とする振動アクチュエータ。 - 請求項1~5のいずれか1項に記載の振動アクチュエータであって、
前記振動体の前記第2の面側は、櫛歯状となるように複数の溝が形成され、
前記移動体の相対移動方向と交差する方向における前記溝の深さは、前記移動体の相対移動方向に沿って異なっていること、を特徴とする振動アクチュエータ。 - 請求項1から7のいずれか1項に記載の振動アクチュエータを備えるレンズ鏡筒。
- 請求項1から7のいずれか1項に記載の振動アクチュエータを備えるカメラ。
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US13/375,981 US8908301B2 (en) | 2009-06-03 | 2010-06-02 | Vibration actuator, lens barrel, and camera |
JP2011518471A JP5541281B2 (ja) | 2009-06-03 | 2010-06-02 | 振動アクチュエータ、レンズ鏡筒及びカメラ |
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JPH04121071A (ja) * | 1990-09-11 | 1992-04-22 | Seiko Instr Inc | 超音波モータ |
JP2000209878A (ja) * | 1999-01-11 | 2000-07-28 | Canon Inc | 摺動部材、それを用いた振動波駆動装置及び機器 |
JP2005328582A (ja) * | 2004-05-12 | 2005-11-24 | Nikon Corp | 振動アクチュエータ |
JP2008259266A (ja) * | 2007-04-02 | 2008-10-23 | Nikon Corp | 振動アクチュエータ、レンズ鏡筒、カメラ |
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JPS59117473A (ja) * | 1982-12-21 | 1984-07-06 | Canon Inc | 振動波モ−タ |
JP4697929B2 (ja) | 2003-11-13 | 2011-06-08 | キヤノン株式会社 | 積層圧電素子及び振動波駆動装置 |
CN101159418B (zh) * | 2007-11-23 | 2011-05-11 | 清华大学 | 一种低压驱动的压电马达 |
JP5256762B2 (ja) * | 2008-02-08 | 2013-08-07 | 株式会社ニコン | レンズ鏡筒、カメラ |
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JPH04121071A (ja) * | 1990-09-11 | 1992-04-22 | Seiko Instr Inc | 超音波モータ |
JP2000209878A (ja) * | 1999-01-11 | 2000-07-28 | Canon Inc | 摺動部材、それを用いた振動波駆動装置及び機器 |
JP2005328582A (ja) * | 2004-05-12 | 2005-11-24 | Nikon Corp | 振動アクチュエータ |
JP2008259266A (ja) * | 2007-04-02 | 2008-10-23 | Nikon Corp | 振動アクチュエータ、レンズ鏡筒、カメラ |
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