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WO2024106146A1 - Vibration wave motor, optical device, and electronic device - Google Patents

Vibration wave motor, optical device, and electronic device Download PDF

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Publication number
WO2024106146A1
WO2024106146A1 PCT/JP2023/038236 JP2023038236W WO2024106146A1 WO 2024106146 A1 WO2024106146 A1 WO 2024106146A1 JP 2023038236 W JP2023038236 W JP 2023038236W WO 2024106146 A1 WO2024106146 A1 WO 2024106146A1
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layers
elastic body
wave motor
vibration wave
energy conversion
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PCT/JP2023/038236
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French (fr)
Japanese (ja)
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亮 島田
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キヤノン株式会社
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    • 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
    • H02N2/02—Electric machines in general using piezoelectric effect, electrostriction or magnetostriction producing linear motion, e.g. actuators; Linear positioners ; Linear motors
    • H02N2/04—Constructional details

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  • the present invention relates to vibration wave motors, optical devices, and electronic devices.
  • a vibration wave motor is known that is driven by pressurizing a rotor, which is a contact body, against a Langevin type vibrator consisting of a piezoelectric element sandwiched between an elastic body such as stainless steel.
  • the driving principle of this type is that by applying a predetermined AC voltage (hereinafter also referred to as "driving voltage") to the piezoelectric element, two bending vibrations perpendicular to the vibrator are generated, causing elliptical or circular motion on the surface of the elastic body, and frictional force causes the rotor to rotate.
  • the electrode layers of this integrally fired multilayer piezoelectric element must be made of an alloy of silver and palladium or platinum in order to withstand the firing temperature of the piezoelectric body.
  • palladium and platinum are precious metals, this increases the cost of the multilayer piezoelectric element.
  • the present invention provides a vibration wave motor equipped with an electromechanical energy conversion element that has low circuit loss and a small number of layers relative to the output mechanical energy.
  • FIG. 1 is an exploded view of a vibration wave motor according to a first embodiment of the present invention
  • 1 is a cross-sectional view of a vibration wave motor according to a first embodiment of the present invention
  • Vibration mode shape of a vibration wave motor according to a first embodiment of the present invention Vibration mode shape of a vibration wave motor according to a first embodiment of the present invention
  • FIG. 2 is an enlarged cross-sectional view of the vicinity of a laminated piezoelectric element of the vibration wave motor according to the first embodiment of the present invention
  • a multilayer piezoelectric element according to a first embodiment of the present invention 1 is an exploded view of a multilayer piezoelectric element according to a first embodiment of the present invention; Graph showing the relationship between the number of active layers and the required applied voltage according to the first embodiment of the present invention. Graph showing the relationship between the number of active layers and the capacitance according to the first embodiment of the present invention. Graph showing the relationship between the number of active layers and heat loss of a circuit according to the first embodiment of the present invention. Graph showing the relationship between the appropriate number of active layers and the active layer thickness according to the first embodiment of the present invention.
  • the "contact body” described below refers to a member that comes into contact with the vibrating body and moves relative to the vibrating body due to vibrations generated in the vibrating body.
  • the contact between the contact body and the vibrating body is not limited to direct contact with no other member interposed between the contact body and the vibrating body.
  • the contact between the contact body and the vibrating body may be indirect contact with another member interposed between the contact body and the vibrating body, as long as the contact body moves relative to the vibrating body due to vibrations generated in the vibrating body.
  • the “other member” is not limited to a member independent of the contact body and the vibrating body (for example, a high-friction material made of a sintered body).
  • the “other member” may be a surface-treated portion formed on the contact body or the vibrating body by plating, nitriding, or the like.
  • the laminated piezoelectric element 3 includes electrode groups (phase A and phase B), each of which consists of two electrodes. AC voltages of different phases are applied to each electrode group from a power source (not shown) via the flexible printed circuit board 4. As a result, two bending vibrations with different spatial phases that displace the vibrator 15 in a direction perpendicular to the central axis of the first elastic body are excited. These vibration modes are shown in Figures 3A to 3C.
  • Figure 3A shows the state when no voltage is applied
  • Figure 3B shows a vibration mode in which the vibrator bends in the X direction (left to right on the paper)
  • Figure 3C shows a vibration mode in which the vibrator bends in the Y direction (vertical on the paper).
  • the rotor ring 8 has a gear 11 on the upper surface in the Z direction in the figure, which transmits output to the outside.
  • a recess is formed on the upper surface of the rotor ring 8, which engages with a protrusion formed on the gear 11.
  • the contact portion 7 rotates around the Z axis (central axis) due to the elliptical motion and frictional force on the first elastic body 1. Therefore, the rotor ring 8 fixed to the contact portion 7, the gear 11 engaged with the rotor ring 8, and the pressure spring 10 and rubber 9 sandwiched between them rotate together around the Z axis (central axis), and the gear 11 transmits output to the outside. Since the gear 11 slides against the flange cap 12 while being subjected to pressure, a material that satisfies strength and wear resistance is preferable, and when cost and noise reduction are taken into account, a resin containing reinforced fibers is most preferable.
  • the vibrating body 15 is fixed to the flange 13, which is a fixed member, by the shaft 5 and nut 14. Between the gear 11 and the flange 13, a flange cap 12, which is a pressure receiving member, is provided.
  • the flange cap 12 may be fixed to the flange 13 with an adhesive or the like.
  • a material that is wear-resistant is preferable for the flange cap 12.
  • Stainless steel press processing is preferable because it has good dimensional accuracy and good productivity.
  • the flange 13 has a complex shape, it is made by resin molding, zinc die casting, aluminum die casting, or metal sintering. In this embodiment, zinc die casting is used, which has a good balance between dimensional accuracy and cost.
  • the gear 11 and flange cap 12 slide in the axial direction, and the gear 11 and flange 13 slide in the radial direction, acting as a sliding bearing.
  • FIG. 4 is an enlarged view of the portion indicated by (DT B) in FIG. 2.
  • the laminated piezoelectric element 3 is formed by alternately laminating active layers 3-1 and electrode layers 3-3, which are polarized piezoelectric bodies, with inactive layers 3-2, which are unpolarized piezoelectric bodies, on the bottom and top layers.
  • the active layer 3-1 is polarized by applying a DC voltage to the electrode layer 3-3 during manufacturing, and expands and contracts in the Z direction due to the inverse piezoelectric effect by applying an AC voltage to the electrode layer 3-3, exciting the vibration described above.
  • the unpolarized inactive layer 3-2 which is also made of a piezoelectric body, serves as a lapping margin for double-sided lapping during manufacturing, and as an insulating layer between the first elastic body 1.
  • the electrode layer 3-3 polarizes the active layer 3-1 during manufacturing, and applies a voltage to the active layer 3-1 during operation.
  • the electrode layers formed on the same layer are not conductive to each other, but every other electrode layer is conductive by a through-hole electrode 3-6 extending in the Z direction.
  • the A+ electrode of the first layer and the A+ electrode of the third layer are conductive.
  • the through-hole electrode 3-6 is exposed on the surface of the laminated piezoelectric element 3, and a voltage is applied to each electrode by pressing the flexible printed circuit board 5 into contact with it.
  • the polarization process is carried out by applying a DC voltage to A+ (+), A- (-), B+ (+) and B- (-) to A+, A-, B+ and B- via the through-hole electrodes 3-6 to the A+, A-, B+ and B- of each electrode layer 3, and to the grounds AG+, AG-, BG+ and BG-.
  • A+ has a polarity of (+)
  • A- has a polarity of (-)
  • B+ has a polarity of (+)
  • B- has a polarity of (-).
  • the laminated piezoelectric element 3 is manufactured by first creating a green sheet that will become the piezoelectric layer from piezoelectric material and an organic binder using the doctor blade method, and then forming the electrode layer 3-3 and the connection electrode 3-6, which are made of a paste of electrode material, at predetermined positions on this green sheet by screen printing. A predetermined number of these green sheets are then stacked on a flat surface and laminated under pressure. The piezoelectric layer and electrode layer are integrated and fired, then a polarization process is performed, and the product is finished by double-sided lapping.
  • the electrode material In order to sinter the piezoelectric layer and electrode layer together in this way, the electrode material must be an expensive precious metal with a high heat resistance, such as platinum or a palladium-silver alloy, so that it can withstand the sintering temperature. In other words, the more layers there are, the more electrode layers 3-3 are used, and the higher the manufacturing costs of the multilayer piezoelectric element 3.
  • the number of layers in the active layer 3-1 is set to five.
  • the force generated also decreases proportionately, so it is necessary to compensate for the decrease in force by increasing the voltage.
  • Figure 6 shows the relationship between the number of active layers and the required applied voltage when generating the same force. It can be seen that the number of active layers and the applied voltage are inversely proportional.
  • ⁇ (white circle) is a plot when the number of active layers is changed while the thickness of the active layers remains constant
  • ⁇ white diamond is a plot when the number of active layers is changed while changing the thickness of the active layers so that the overall length of the laminated piezoelectric element 3 remains constant.
  • the active layer thickness is constant, the number of active layers is proportional to the capacitance, whereas when the overall length is constant, in addition to the effect of the number of layers, the thickness of the active layers is also proportional to the capacitance, so the square of the number of active layers is proportional to the capacitance.
  • the current and heat loss P on the primary side are calculated as follows: I1 ⁇ (C ⁇ n ⁇ V/n ⁇ N/n) P ⁇ (C ⁇ n ⁇ V / n ⁇ N / n) 2 P ⁇ (C ⁇ V ⁇ N/n) 2
  • the heat loss P is calculated as follows: I1 ⁇ (C ⁇ n2 ⁇ V/n ⁇ N/n) P ⁇ (C ⁇ n 2 ⁇ V / n ⁇ N / n) 2 P ⁇ (C V N) 2
  • the heat loss will be a constant value regardless of the number of active layers.
  • FIG. 9 The relationship between the number of active layers and thickness suitable for achieving the effects of the present invention is shown in FIG. 9. If the thickness of the active layer 3-1 is thin, as mentioned above, the capacitance increases and the circuit loss increases, so it is preferable that it is 0.26 mm or more (dashed line A in FIG. 9). On the other hand, if it is too thick, polarization becomes difficult, so it is preferable that it is 1.00 mm or less (dashed line B in FIG. 9). Furthermore, when the thickness of the active layer 3-1 of the laminated piezoelectric element 3 is t1 and the number of layers is n, it is preferable that n ⁇ t1 is 1.07 mm or more (dashed line C in FIG.
  • the number of active layers is two or more and four or less.
  • the configuration of a laminated piezoelectric element 3 with two layers is shown in Figures 10A and 10B.
  • the number of active layers is two and the thickness is 0.9 mm. This makes it possible to minimize the amount of electrodes used.
  • T ⁇ 30 x t2 and t1 ⁇ 2 x t2 be satisfied, where t2 is the thickness of the inactive layer 3-2 and T is the overall length (total thickness) of the laminated piezoelectric element 3. This is because if the inactive layer 3-2 is thick, it will increase the axial size of the vibration wave motor and cause vibration inhibition.
  • the appropriate range of capacitance in this embodiment will be described with reference to Fig. 11.
  • the configuration of the vibration wave motor is the same as that in the first embodiment, so the description will be omitted. If the capacitance is C and the unit of C is nF, and the number of layers of the active layer is n, it is preferable that 0.05n2nF (dashed line G in Fig. 11) ⁇ C ⁇ 0.14n2nF (dashed line F in Fig. 11) is satisfied.
  • the number of active layers should be 2 or more, as in Example 2 (Dotted line E in Figure 11), and 14 layers or less is desirable from the viewpoint of reducing the amount of electrodes used (Dotted line H in Figure 11).
  • the vibration wave driving device can be used, for example, for driving lenses in imaging devices (optical devices, electronic devices).
  • imaging devices optical devices, electronic devices.
  • FIG. 12A is a top view showing the schematic configuration of the imaging device 700.
  • the imaging device 700 includes a camera body 730 equipped with an imaging element 710 and a power button 720.
  • the imaging device 700 also includes a lens barrel 740 having a first lens group (not shown), a second lens group 320, a third lens group (not shown), a fourth lens group 340, and vibration type drive devices 620 and 640.
  • the lens barrel 740 is replaceable as an interchangeable lens, and a lens barrel 740 suitable for the subject to be photographed can be attached to the camera body 730.
  • the second lens group 320 and the fourth lens group 340 are driven by the two vibration type drive devices 620 and 640, respectively.
  • the detailed configuration of the vibration type driving device 620 is not shown, but the vibration type driving device 620 has a vibration wave driving device and a driving circuit for the vibration wave driving device.
  • the rotor 211 which is composed of the contact portion 7 and the rotor main ring 8, is arranged inside the lens barrel 740 so that the radial direction is approximately perpendicular to the optical axis.
  • the vibration type driving device 620 the rotor 211 is rotated around the optical axis, and the rotational output of the contact body is converted into linear motion in the optical axis direction via gears (not shown), thereby moving the second lens group 320 in the optical axis direction.
  • the vibration type driving device 640 has a configuration similar to that of the vibration type driving device 620, and moves the fourth lens group 340 in the optical axis direction.
  • FIG. 12B is a block diagram showing the schematic configuration of the imaging device 700.
  • the first lens group 3a0, the second lens group 320, the third lens group 330, the fourth lens group 340, and the light amount adjustment unit 350 are arranged at predetermined positions on the optical axis inside the lens barrel 740.
  • Light that passes through the first lens group 3a0 to the fourth lens group 340 and the light amount adjustment unit 350 forms an image on the imaging element 710.
  • the imaging element 710 converts the optical image into an electrical signal and outputs it, and the output is sent to the camera processing circuit 750.
  • the camera processing circuit 750 performs amplification, gamma correction, etc. on the output signal from the image sensor 710.
  • the camera processing circuit 750 is connected to the CPU 790 via an AE gate 755, and is also connected to the CPU 790 via an AF gate 760 and an AF signal processing circuit 765.
  • the video signal that has been subjected to a predetermined process in the camera processing circuit 750 is sent to the CPU 790 via the AE gate 755, AF gate 760, and AF signal processing circuit 765.
  • the AF signal processing circuit 765 extracts high frequency components from the video signal to generate an evaluation value signal for autofocus (AF), and supplies the generated evaluation value to the CPU 790.
  • the CPU 790 is a control circuit that controls the overall operation of the imaging device 700, and generates control signals for determining exposure and adjusting focus from the acquired video signal.
  • the CPU 790 adjusts the optical axis positions of the second lens group 320, the fourth lens group 340, and the light amount adjustment unit 350 by controlling the driving of the vibration type driving devices 620, 640 and the meter 630 so as to obtain the determined exposure and appropriate focus state.
  • the vibration type driving device 620 moves the second lens group 320 in the optical axis direction
  • the vibration type driving device 640 moves the fourth lens group 340 in the optical axis direction
  • the light amount adjustment unit 350 is driven and controlled by the meter 630.
  • the optical axis direction position of the second lens group 320 driven by the vibration type driving device 620 is detected by a first linear encoder 770, and the detection result is notified to the CPU 790, which feeds back the drive of the vibration type driving device 620.
  • the optical axis direction position of the fourth lens group 340 driven by the vibration type driving device 640 is detected by a second linear encoder 775, and the detection result is notified to the CPU 790, which feeds back the drive of the vibration type driving device 640.
  • the optical axis direction position of the light amount adjustment unit 350 is detected by an aperture encoder 780, and the detection result is notified to the CPU 790, which feeds back the drive of the meter 630.

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  • General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)

Abstract

This vibration wave motor rotates a contact body about the central axis of a first elastic body by exciting a vibration body through two bending vibration modes for displacement in directions orthogonal to the central axis. The vibration wave motor is characterized in that: an electrical-mechanical energy conversion element is formed by alternately laminating active layers, which are polarized piezoelectric bodies, and electrode layers; the number of the active layers is two or more and the number of the electrode layers is three or more; and, when t1 represents the thickness of each of the active layers, 0.26 mm≤t1≤1.00 mm is satisfied.

Description

振動波モータ、光学機器及び電子機器Vibration wave motors, optical devices and electronic devices
　本発明は、振動波モータ、光学機器及び電子機器に関する。 The present invention relates to vibration wave motors, optical devices, and electronic devices.
　圧電素子などの電気－機械エネルギー変換素子を用いた振動波モータには種々の構成のものが知られている。例えば、圧電素子をステンレス等の弾性体で挟持して構成するランジュバン型振動体に接触体であるロータを加圧接触させて駆動する振動波モータが知られている。この駆動原理は、圧電素子に所定の交流電圧（以下、「駆動電圧」ともいう）を印加することによって、振動体に直交する２つの曲げ振動を発生させことで、弾性体表面に楕円運動又は円運動を起こし、摩擦力によりロータを回転運動させるというものである。 Various configurations of vibration wave motors using electromechanical energy conversion elements such as piezoelectric elements are known. For example, a vibration wave motor is known that is driven by pressurizing a rotor, which is a contact body, against a Langevin type vibrator consisting of a piezoelectric element sandwiched between an elastic body such as stainless steel. The driving principle of this type is that by applying a predetermined AC voltage (hereinafter also referred to as "driving voltage") to the piezoelectric element, two bending vibrations perpendicular to the vibrator are generated, causing elliptical or circular motion on the surface of the elastic body, and frictional force causes the rotor to rotate.
　圧電素子は、電気的エネルギーを機械的エネルギーに変換する電気－機械エネルギー変換機能を有する代表的な材料である圧電材料から構成され、振動波モータや圧電アクチュエータなどを始めとして、多種多様な圧電素子を使った圧電アクチュエータに使われている。 Piezoelectric elements are made from piezoelectric material, a representative material with electro-mechanical energy conversion function that converts electrical energy into mechanical energy, and are used in a wide variety of piezoelectric actuators, including vibration wave motors and piezoelectric actuators.
　特に最近は、単一の板状の圧電素子だけでなく、複数の圧電層と電極層とを交互に重ねて積層化し、一体焼成した積層圧電素子や単一板状に焼成した圧電素子を積み重ねて接着した素子が使われている。これは積層化によって、単一の板状の圧電素子と比べて低電圧で大きな変位や大きな力が得られるためである。とりわけ、小型化や薄層化には一体焼成した積層圧電素子が適している。 In particular, in recent years, in addition to single plate-shaped piezoelectric elements, multi-layer piezoelectric elements in which multiple piezoelectric layers and electrode layers are alternately stacked and laminated and fired as a single unit, and elements in which piezoelectric elements fired as single plates are stacked and glued together, are being used. This is because stacking allows for greater displacement and force to be obtained at a lower voltage than with single plate-shaped piezoelectric elements. In particular, multi-layer piezoelectric elements fired as a single unit are well suited for making them smaller and thinner.
　ところでこの一体で焼成した積層圧電素子の電極層には圧電体の焼成温度に耐えられるように、銀にパラジウムを混合した合金や白金を使用する必要があるが、これらパラジウムや白金は貴金属のため、積層圧電素子のコストを上昇させる要因となっていた。 The electrode layers of this integrally fired multilayer piezoelectric element must be made of an alloy of silver and palladium or platinum in order to withstand the firing temperature of the piezoelectric body. However, because palladium and platinum are precious metals, this increases the cost of the multilayer piezoelectric element.
　これに対し特許文献１では圧電体に焼結助剤を添加し、焼成温度を低下させることでパラジウム比率を下げる手法が提案されている。しかしながら焼結助剤は圧電特性に寄与しないため、この手法だと圧電体の圧電定数が１割程度低下する問題があった。 In response to this, Patent Document 1 proposes a method of lowering the palladium ratio by adding a sintering aid to the piezoelectric body and lowering the firing temperature. However, because the sintering aid does not contribute to the piezoelectric properties, this method has the problem of lowering the piezoelectric constant of the piezoelectric body by about 10%.
　この問題に対し、焼結温度を変えずに積層数を減らせば、圧電定数を保ったままパラジウムだけでなく銀の使用量も減らすことができるが、単純に積層数を減らし、それを補う電圧を与えてしまうと、電流が増加し、回路損失が大きくなってしまう。 　To address this issue, if the number of layers is reduced without changing the sintering temperature, it is possible to reduce the amount of silver used as well as palladium while maintaining the piezoelectric constant. However, simply reducing the number of layers and applying a voltage to compensate for this will increase the current and lead to greater circuit loss.
特開２０１２－１９１７３３Patent Publication 2012-191733
　本願発明は回路損失が小さく、出力される機械的エネルギーに対して積層数が少ない電気－機械エネルギー変換素子を備えた振動波モータを提供する。 The present invention provides a vibration wave motor equipped with an electromechanical energy conversion element that has low circuit loss and a small number of layers relative to the output mechanical energy.
　上記課題を解決する振動波モータは、
　第１の弾性体と、第２の弾性体と、前記第１の弾性体と前期第２の弾性体に挟持された電気－機械エネルギー変換素子とを有する振動体と、
　前記第１の弾性体に接触する接触体と、を備え、
　前記電気－機械エネルギー変換素子に電圧を印加することで、前記振動体に前記第１の弾性体の中心軸と直交する方向に変位する空間的位相が異なる２つの曲げ振動モードを励振することで、前記接触体を前記中心軸周りに回転させる振動波モータにおいて、
　前記前記電気－機械エネルギー変換素子は、分極された圧電体である活性層と、電極層が交互に積層されており、
　前記活性層は２層以上、前記電極層は３層以上であり、
　前記活性層の厚みをｔ１としたとき、０．２６ｍｍ≦ｔ１≦１．００ｍｍを満たすことを特徴とする。 The oscillatory wave motor that solves the above problems is as follows:
a vibrator having a first elastic body, a second elastic body, and an electromechanical energy conversion element sandwiched between the first elastic body and the second elastic body;
a contact body that contacts the first elastic body,
a vibration wave motor for rotating the contact body around the central axis by exciting two bending vibration modes having different spatial phases in which the vibration body is displaced in a direction perpendicular to the central axis of the first elastic body by applying a voltage to the electromechanical energy conversion element,
The electromechanical energy conversion element is formed by alternately stacking active layers, which are polarized piezoelectric bodies, and electrode layers,
The active layer has two or more layers, and the electrode layer has three or more layers,
When the thickness of the active layer is taken as t1, it is characterized in that 0.26 mm≦t1≦1.00 mm is satisfied.
　本発明によれば、回路損失が小さく、出力される機械的エネルギーに対して積層数が少ない電気－機械エネルギー変換素子を備えた振動波モータを提供することができる。 The present invention provides a vibration wave motor equipped with an electromechanical energy conversion element that has low circuit loss and a small number of layers relative to the output mechanical energy.
本発明の第１の実施の形態に係る振動波モータの分解図1 is an exploded view of a vibration wave motor according to a first embodiment of the present invention; 本発明の第１の実施の形態に係る振動波モータの断面図1 is a cross-sectional view of a vibration wave motor according to a first embodiment of the present invention; 本発明の第１の実施の形態に係る振動波モータの振動モード形状Vibration mode shape of a vibration wave motor according to a first embodiment of the present invention 本発明の第１の実施の形態に係る振動波モータの振動モード形状Vibration mode shape of a vibration wave motor according to a first embodiment of the present invention 本発明の第１の実施の形態に係る振動波モータの振動モード形状Vibration mode shape of a vibration wave motor according to a first embodiment of the present invention 本発明の第１の実施の形態に係る振動波モータの積層圧電素子周辺の拡大断面図FIG. 2 is an enlarged cross-sectional view of the vicinity of a laminated piezoelectric element of the vibration wave motor according to the first embodiment of the present invention; 本発明の第１の実施の形態に係る積層圧電素子1. A multilayer piezoelectric element according to a first embodiment of the present invention 本発明の第１の実施の形態に係る積層圧電素子の分解図1 is an exploded view of a multilayer piezoelectric element according to a first embodiment of the present invention; 本発明の第１の実施の形態に係る活性層数と必要な印加電圧の関係を表すグラフGraph showing the relationship between the number of active layers and the required applied voltage according to the first embodiment of the present invention. 本発明の第１の実施の形態に係る活性層数と静電容量の関係を表すグラフGraph showing the relationship between the number of active layers and the capacitance according to the first embodiment of the present invention. 本発明の第１の実施の形態に係る活性層数と回路の熱損失の関係を表すグラフGraph showing the relationship between the number of active layers and heat loss of a circuit according to the first embodiment of the present invention. 本発明の第１の実施の形態に係る適切な活性層数と活性層厚みの関係を表すグラフGraph showing the relationship between the appropriate number of active layers and the active layer thickness according to the first embodiment of the present invention. 本発明の第１の実施の形態に係る活性層数が２の場合の積層圧電素子A laminated piezoelectric element having two active layers according to a first embodiment of the present invention 本発明の第１の実施の形態に係る活性層数が２の場合の積層圧電素子の分解図1 is an exploded view of a multilayer piezoelectric element having two active layers according to a first embodiment of the present invention; 本発明の第２の実施の形態に係る適切な活性層数と静電容量の関係を表すグラフGraph showing the relationship between the appropriate number of active layers and capacitance according to the second embodiment of the present invention. 本発明の実施例７における振動波駆動装置を用いた撮像装置の概略構成を示す上面図であるFIG. 13 is a top view showing a schematic configuration of an imaging device using a vibration wave driving device according to a seventh embodiment of the present invention. 本発明の実施例７における振動波駆動装置を用いた撮像装置の概略構成を示すブロック図であるA block diagram showing a schematic configuration of an imaging device using a vibration wave driving device according to a seventh embodiment of the present invention.
　本発明を実施するための振動波モータの一例は以下の通りである。 An example of a vibration wave motor for implementing the present invention is as follows:
　振動波モータは、第１の弾性体と、第２の弾性体と、第１の弾性体と第２の弾性体に挟持された電気－機械エネルギー変換素子とを有する振動体と、第１の弾性体に接触する接触体と、を備えている。また、この振動波モータは、電気－機械エネルギー変換素子に電圧を印加することで、振動体に第１の弾性体の中心軸と直交する方向に変位する２つの曲げ振動モードを励振することで、接触体を中心軸周りに回転させる振動波モータである。 The vibration wave motor includes a vibrator having a first elastic body, a second elastic body, and an electromechanical energy conversion element sandwiched between the first elastic body and the second elastic body, and a contact body that contacts the first elastic body. This vibration wave motor is a vibration wave motor that rotates the contact body around the central axis by applying a voltage to the electromechanical energy conversion element to excite the vibrator into two bending vibration modes that displace in a direction perpendicular to the central axis of the first elastic body.
　上記の電気－機械エネルギー変換素子は、分極された圧電体である活性層と、電極層が交互に積層された構成であり、活性層は２層以上、前記電極層は３層以上である。この活性層の厚みをｔ１としたとき、０．２６ｍｍ≦ｔ１≦１．００ｍｍを満たす。 The electromechanical energy conversion element is configured such that active layers, which are polarized piezoelectric bodies, and electrode layers are alternately laminated, with the active layers being two or more layers and the electrode layers being three or more layers. When the thickness of this active layer is t1, it satisfies 0.26 mm≦t1≦1.00 mm.
　以下、発明を実施するための形態の例を図面を用いて詳細に説明する。なお以下で説明する「接触体」とは、振動体と接触し、振動体に発生した振動によって、振動体に対して相対移動する部材のことをいう。接触体と振動体の接触は、接触体と振動体の間に他の部材が介在しない直接接触に限られない。接触体と振動体の接触は、振動体に発生した振動によって、接触体が振動体に対して相対移動するならば、接触体と振動体の間に他の部材が介在する間接接触であってもよい。「他の部材」は、接触体及び振動体とは独立した部材（例えば焼結体よりなる高摩擦材）に限られない。「他の部材」は、接触体又は振動体に、メッキや窒化処理などによって形成された表面処理部分であってもよい。 Below, examples of embodiments of the invention will be described in detail with reference to the drawings. Note that the "contact body" described below refers to a member that comes into contact with the vibrating body and moves relative to the vibrating body due to vibrations generated in the vibrating body. The contact between the contact body and the vibrating body is not limited to direct contact with no other member interposed between the contact body and the vibrating body. The contact between the contact body and the vibrating body may be indirect contact with another member interposed between the contact body and the vibrating body, as long as the contact body moves relative to the vibrating body due to vibrations generated in the vibrating body. The "other member" is not limited to a member independent of the contact body and the vibrating body (for example, a high-friction material made of a sintered body). The "other member" may be a surface-treated portion formed on the contact body or the vibrating body by plating, nitriding, or the like.
　［発明の実施の形態］
　図１は、本発明の第１の実施の形態に係る振動波モータの分解図、図２は本発明の第１の実施の形態に係る振動波モータの断面図である。図１と図２を用いて、本実施例の振動波モータの基本原理について説明する。 [Embodiments of the invention]
Fig. 1 is an exploded view of a vibration wave motor according to a first embodiment of the present invention, and Fig. 2 is a cross-sectional view of the vibration wave motor according to the first embodiment of the present invention. The basic principle of the vibration wave motor of this embodiment will be described with reference to Figs. 1 and 2.
　１は第１の弾性体、２は第２の弾性体、３は積層圧電素子（電気－機械エネルギー変換素子）、４はフレキシブルプリント基板、５シャフト、６はナットである。第１の弾性体１、第２の弾性体２、積層圧電素子３、及びフレキシブルプリント基板４は、シャフト５及びナット６によって、所定の挟持力が付与されるように締め付けられ、シャフト５が延在する方向を中心軸とする棒状の振動体１５を構成している。 1 is the first elastic body, 2 is the second elastic body, 3 is a laminated piezoelectric element (electro-mechanical energy conversion element), 4 is a flexible printed circuit board, 5 is a shaft, and 6 is a nut. The first elastic body 1, the second elastic body 2, the laminated piezoelectric element 3, and the flexible printed circuit board 4 are fastened by the shaft 5 and the nut 6 so that a predetermined clamping force is applied, forming a rod-shaped vibrating body 15 whose central axis is in the direction in which the shaft 5 extends.
　積層圧電素子３には、それぞれが２つの電極からなる電極群（Ａ相とＢ相）が含まれる。不図示の電源から、フレキシブルプリント基板４を介して、それぞれの電極群に位相の異なる交流電圧が印加される。その結果、振動体１５に、振動体に前記第１の弾性体の中心軸と直交する方向に変位する空間的位相が異なる２つの曲げ振動が励振される。その振動モードを表したのが図３Ａ～図３Ｃである。図３Ａは電圧を印可していない状態で、図３ＢはＸ方向（紙面左右方向）に曲がる振動モード、図３ＣはＹ方向（紙面鉛直方向）に曲がる振動モードである。 The laminated piezoelectric element 3 includes electrode groups (phase A and phase B), each of which consists of two electrodes. AC voltages of different phases are applied to each electrode group from a power source (not shown) via the flexible printed circuit board 4. As a result, two bending vibrations with different spatial phases that displace the vibrator 15 in a direction perpendicular to the central axis of the first elastic body are excited. These vibration modes are shown in Figures 3A to 3C. Figure 3A shows the state when no voltage is applied, Figure 3B shows a vibration mode in which the vibrator bends in the X direction (left to right on the paper), and Figure 3C shows a vibration mode in which the vibrator bends in the Y direction (vertical on the paper).
　さらに印加交流電界の位相を調整することにより、上述した振動体の中心軸まわりの空間的な位相が９０度ずれたこれら２つの振動モードに、９０度の時間的な位相差を与えることができる。その結果、振動体１５の曲げ振動が中心軸の周りに回転し、第１の弾性体１上には楕円運動が発生する。そして第１の弾性体１に後述する接触体の接触部７を加圧接触させることにより、摩擦力で接触部７がＺ軸（中心軸）周りに回転する。 Furthermore, by adjusting the phase of the applied AC electric field, it is possible to give a temporal phase difference of 90 degrees to these two vibration modes, which have a spatial phase difference of 90 degrees around the central axis of the vibrating body described above. As a result, the bending vibration of the vibrating body 15 rotates around the central axis, and elliptical motion is generated on the first elastic body 1. Then, by pressing the contact part 7 of the contact body described later into contact with the first elastic body 1, the frictional force causes the contact part 7 to rotate around the Z axis (central axis).
　接触体は接触部７およびロータ本環８を備えている。接触部７は第１の弾性体１との接触面積が小さく、かつ適度なバネ性を有する構造となっている。接触部７の材料は耐摩耗性や強度、耐食性を兼ね備えたステンレス鋼が好ましく、より好ましくはＳＵＳ４２０Ｊ２である。旋盤加工や３Ｄプリンター等で加工可能であるが、プレス加工が加工精度、コストの点で好ましい。接触部７は樹脂接着剤による接着や、半田などの金属ろう付け、レーザー溶接、抵抗溶接などの溶接、圧入や、かしめ等の機械的接合で、ロータ本環８に固定される。 The contact body includes a contact portion 7 and a rotor ring 8. The contact portion 7 has a small contact area with the first elastic body 1 and is structured to have moderate springiness. The material of the contact portion 7 is preferably stainless steel, which combines abrasion resistance, strength, and corrosion resistance, and more preferably SUS420J2. It can be processed using a lathe or a 3D printer, but press processing is preferred in terms of processing accuracy and cost. The contact portion 7 is fixed to the rotor ring 8 by adhesion using a resin adhesive, metal brazing such as solder, welding such as laser welding or resistance welding, or mechanical joining such as pressing or crimping.
　ロータ本環８はゴム９を介して加圧バネ１０で加圧されている。このように加圧されることで接触体の接触部７と第１の弾性体１の間に摩擦力が生まれ、前述した楕円運動によって接触体を駆動させることができる。なおゴム９は加圧力を均一化しつつ、ばね９及びロータ本環８の不要な振動を低減する働きをしている。 The rotor ring 8 is pressurized by a pressure spring 10 via rubber 9. This pressure creates friction between the contact portion 7 of the contact body and the first elastic body 1, allowing the contact body to be driven by the elliptical motion described above. The rubber 9 also works to equalize the pressure while reducing unnecessary vibrations of the spring 9 and rotor ring 8.
　ロータ本環８の図中のＺ方向の上部の面には外部への出力伝達を担うギア１１が設けられ、またロータ本環８の上面には凹部が形成され、ギア１１に形成された凸部と係合している。上述のように第１の弾性体１上の楕円運動と摩擦力により、接触部７がＺ軸（中心軸）周りに回転する。そのため、接触部７に固定されたロータ本環８、ロータ本環８と係合しているギア１１、およびそれらに挟まれた加圧ばね１０、ゴム９が一体となってＺ軸（中心軸）周りに回転し、ギア１１が外部に出力を伝達する。なおギア１１は加圧を受けつつフランジキャップ１２と摺動するため、強度と耐摩耗性を満たす材料が好ましく、コストと静音性を加味すると強化繊維入りの樹脂が最も好ましい。 The rotor ring 8 has a gear 11 on the upper surface in the Z direction in the figure, which transmits output to the outside. A recess is formed on the upper surface of the rotor ring 8, which engages with a protrusion formed on the gear 11. As described above, the contact portion 7 rotates around the Z axis (central axis) due to the elliptical motion and frictional force on the first elastic body 1. Therefore, the rotor ring 8 fixed to the contact portion 7, the gear 11 engaged with the rotor ring 8, and the pressure spring 10 and rubber 9 sandwiched between them rotate together around the Z axis (central axis), and the gear 11 transmits output to the outside. Since the gear 11 slides against the flange cap 12 while being subjected to pressure, a material that satisfies strength and wear resistance is preferable, and when cost and noise reduction are taken into account, a resin containing reinforced fibers is most preferable.
　振動体１５はシャフト５とナット１４によって固定部材であるフランジ１３に固定される。ギア１１とフランジ１３の間には加圧受け部材であるフランジキャップ１２が設けられている。フランジキャップ１２はフランジ１３に対して接着剤等で固定してもよい。フランジキャップ１２の材料は耐摩耗性がある材料が好ましい。ステンレスのプレス加工だと寸法精度も良く、生産性も良いのでより好ましい。またフランジ１３は複雑な形状のため、樹脂成型や亜鉛ダイキャスト、アルミダイキャスト、または金属焼結で構成する。本実施例では寸法精度・コストのバランスがいい亜鉛ダイキャストを用いている。軸方向にギア１１とフランジキャップ１２、径方向にギア１１とフランジ１３とが摺動して滑り軸受の役目を果たしている。 The vibrating body 15 is fixed to the flange 13, which is a fixed member, by the shaft 5 and nut 14. Between the gear 11 and the flange 13, a flange cap 12, which is a pressure receiving member, is provided. The flange cap 12 may be fixed to the flange 13 with an adhesive or the like. A material that is wear-resistant is preferable for the flange cap 12. Stainless steel press processing is preferable because it has good dimensional accuracy and good productivity. In addition, since the flange 13 has a complex shape, it is made by resin molding, zinc die casting, aluminum die casting, or metal sintering. In this embodiment, zinc die casting is used, which has a good balance between dimensional accuracy and cost. The gear 11 and flange cap 12 slide in the axial direction, and the gear 11 and flange 13 slide in the radial direction, acting as a sliding bearing.
　図４は図２において（ＤＴ　Ｂ）で示す拡大図である。積層圧電素子３は、分極された圧電体である活性層３－１と電極層３－３が交互に積層され、最下層、最上層には分極されていない圧電体である不活性層３－２が設けられている。活性層３－１は製造時に電極層３－３に直流電圧を印加することにより分極され、電極層３－３に交流電圧を印加することで逆圧電効果によりＺ方向に伸縮し、前述の振動を励振する。また圧電体が構成されているが、分極されていない不活性層３－２は、製造時の両面ラップ加工におけるラップしろと、第１の弾性体１との絶縁層としての役割を果たしている。電極層３－３は製造時に活性層３－１を分極し、駆動時には活性層３－１に電圧を印加する役割を担っている。 FIG. 4 is an enlarged view of the portion indicated by (DT B) in FIG. 2. The laminated piezoelectric element 3 is formed by alternately laminating active layers 3-1 and electrode layers 3-3, which are polarized piezoelectric bodies, with inactive layers 3-2, which are unpolarized piezoelectric bodies, on the bottom and top layers. The active layer 3-1 is polarized by applying a DC voltage to the electrode layer 3-3 during manufacturing, and expands and contracts in the Z direction due to the inverse piezoelectric effect by applying an AC voltage to the electrode layer 3-3, exciting the vibration described above. The unpolarized inactive layer 3-2, which is also made of a piezoelectric body, serves as a lapping margin for double-sided lapping during manufacturing, and as an insulating layer between the first elastic body 1. The electrode layer 3-3 polarizes the active layer 3-1 during manufacturing, and applies a voltage to the active layer 3-1 during operation.
　図５Ａは積層圧電素子３の斜視図、図５Ｂはそれを各層ごとに分解して示した図である。活性層３－１は電極層３－３が形成された電極部３－４と、形成されていない非電極層３－５で構成され、非電極層３－５については当然分極されていない。また各層の電極は９０度ごとに４つに分割されており、図中では、Ａ＋、Ａ－、Ｂ＋、Ｂ－が同一の層に形成され、またＡＧ＋、ＡＧ－、ＢＧ＋、ＢＧ－も隣の別の同一の層に形成され、それが交互に積層されている。同一の層に形成された各電極層は互いに非導通となっているが、各電極層は１層おきに、Ｚ方向に延びるスルーホール電極３－６によって導通している。例えば、１層目のＡ＋電極と３層目のＡ＋電極が導通している。そして、積層圧電素子３の表面にスルーホール電極３－６が露出し、フレキシブルプリント基板５を加圧接触させることによって各電極に電圧を印加する。 FIG. 5A is a perspective view of the laminated piezoelectric element 3, and FIG. 5B is a view showing it disassembled into each layer. The active layer 3-1 is composed of an electrode part 3-4 on which an electrode layer 3-3 is formed, and a non-electrode layer 3-5 on which no electrode layer 3-3 is formed, and the non-electrode layer 3-5 is naturally not polarized. The electrodes of each layer are divided into four parts at 90 degree intervals, and in the figure, A+, A-, B+, and B- are formed on the same layer, and AG+, AG-, BG+, and BG- are also formed on another adjacent same layer, and these are laminated alternately. The electrode layers formed on the same layer are not conductive to each other, but every other electrode layer is conductive by a through-hole electrode 3-6 extending in the Z direction. For example, the A+ electrode of the first layer and the A+ electrode of the third layer are conductive. The through-hole electrode 3-6 is exposed on the surface of the laminated piezoelectric element 3, and a voltage is applied to each electrode by pressing the flexible printed circuit board 5 into contact with it.
　分極処理はスルーホール電極３－６を介して各電極層３のＡ＋、Ａ－、Ｂ＋、Ｂ－に、グランドであるＡＧ＋、ＡＧ－、ＢＧ＋、ＢＧ－に対し、直流電圧をＡ＋に（＋）、Ａ－に（－）、Ｂ＋に（＋）、Ｂ－に（－）を印加する。すなわち、グランドであるＡＧ＋、ＡＧ－、ＢＧ＋、ＢＧ－に対し、Ａ＋は極性（＋）、Ａ－は極性（－）、Ｂ＋は極性（＋）、Ｂ－は極性（－）になるようにする。 The polarization process is carried out by applying a DC voltage to A+ (+), A- (-), B+ (+) and B- (-) to A+, A-, B+ and B- via the through-hole electrodes 3-6 to the A+, A-, B+ and B- of each electrode layer 3, and to the grounds AG+, AG-, BG+ and BG-. In other words, with respect to the grounds AG+, AG-, BG+ and BG-, A+ has a polarity of (+), A- has a polarity of (-), B+ has a polarity of (+) and B- has a polarity of (-).
　積層圧電素子３の製造は、まず圧電材料と有機バインダから、ドクターブレード法により圧電層となるグリーンシートを作り、このグリーンシート上の所定位置にスクリーン印刷によって電極材料のペーストからなる電極層３―３と接続電極３－６を形成する。そして、このグリーンシートを所定の枚数平面状に重ね、加圧して積層化し、圧電層と電極層を一体化焼成したのち分極処理を行い、両面ラップ加工により仕上げた。 The laminated piezoelectric element 3 is manufactured by first creating a green sheet that will become the piezoelectric layer from piezoelectric material and an organic binder using the doctor blade method, and then forming the electrode layer 3-3 and the connection electrode 3-6, which are made of a paste of electrode material, at predetermined positions on this green sheet by screen printing. A predetermined number of these green sheets are then stacked on a flat surface and laminated under pressure. The piezoelectric layer and electrode layer are integrated and fired, then a polarization process is performed, and the product is finished by double-sided lapping.
　このように圧電層と電極層を一体焼成するために、電極材料は焼成温度に耐えられるよう白金やパラジウム‐銀合金などの耐熱温度の高い高価な貴金属が必要となる。つまり積層数が増えるほど電極層３－３の使用量が増え、積層圧電素子３の製造コストが上昇することになる。 In order to sinter the piezoelectric layer and electrode layer together in this way, the electrode material must be an expensive precious metal with a high heat resistance, such as platinum or a palladium-silver alloy, so that it can withstand the sintering temperature. In other words, the more layers there are, the more electrode layers 3-3 are used, and the higher the manufacturing costs of the multilayer piezoelectric element 3.
　本実施例は、この点に考慮し、活性層３－１の積層数を５層にしている。ただし、積層数を低下させると、それに比例して発生する力も低下するため、電圧を大きくすることで力の低下を補う必要がある。図６に同一の力を発生する場合の活性層数と必要な印加電圧の関係を示す。活性層数と印加電圧は反比例の関係にあることが分かる。 In this embodiment, taking this into consideration, the number of layers in the active layer 3-1 is set to five. However, as the number of layers is reduced, the force generated also decreases proportionately, so it is necessary to compensate for the decrease in force by increasing the voltage. Figure 6 shows the relationship between the number of active layers and the required applied voltage when generating the same force. It can be seen that the number of active layers and the applied voltage are inversely proportional.
　一方で、活性層数と静電容量の関係を図７に示す。図７において〇（白マル）は活性層の厚みが一定のまま活性層数を変更した場合のプロットで、◇（白ひし形）は積層圧電素子３の全長が一定になるように活性層の厚みを変えながら活性層数を変更した場合のプロットである。活性層厚み一定の場合、活性層数と静電容量は比例する、一方、全長一定の場合は積層数の効果に加えて活性層の厚みも静電容量に比例するので、活性層数の２乗が静電容量に比例することになる。 On the other hand, the relationship between the number of active layers and capacitance is shown in Figure 7. In Figure 7, ◯ (white circle) is a plot when the number of active layers is changed while the thickness of the active layers remains constant, and ◇ (white diamond) is a plot when the number of active layers is changed while changing the thickness of the active layers so that the overall length of the laminated piezoelectric element 3 remains constant. When the active layer thickness is constant, the number of active layers is proportional to the capacitance, whereas when the overall length is constant, in addition to the effect of the number of layers, the thickness of the active layers is also proportional to the capacitance, so the square of the number of active layers is proportional to the capacitance.
　図８は活性層数と回路の熱損失の関係を示したグラフである。ここでトランス回路の１次側の熱損失は１次側の電流の２乗に比例し、以下の式で表すことができる。
Ｐ∝（Ｉ１）２ 8 is a graph showing the relationship between the number of active layers and the heat loss of the circuit. Here, the heat loss on the primary side of the transformer circuit is proportional to the square of the current on the primary side and can be expressed by the following formula.
P ∝ (I 1 ) 2
　ここで活性層厚み一定の場合、活性層が１層時に必要な印加電圧をＶ、静電容量をＣ、トランスの巻き線比をＮとしたとき、活性層数ｎの場合の電圧はＶ／ｎ、静電容量はＣ×ｎ、巻き線比はＮ／ｎ倍となる。以上から１次側の電流及び熱損失Ｐは以下のようになる。
Ｉ１∝（Ｃ×ｎ×Ｖ／ｎ×Ｎ／ｎ）
Ｐ∝（Ｃ×ｎ×Ｖ／ｎ×Ｎ／ｎ）２
Ｐ∝（Ｃ・Ｖ・Ｎ／ｎ）２ In the case where the active layer thickness is constant, the voltage required for one active layer is V, the capacitance is C, and the winding ratio of the transformer is N. In the case where the number of active layers is n, the voltage is V/n, the capacitance is C×n, and the winding ratio is N/n. From the above, the current and heat loss P on the primary side are calculated as follows:
I1 ∝(C×n×V/n×N/n)
P ∝ (C × n × V / n × N / n) 2
P ∝ (C × V × N/n) 2
　つまり活性層厚み一定の場合、活性層数が減るほど、図８のように熱損失が増大してしまうことになる。なお２次側の熱損失も同じく活性層数の２乗に反比例し、グラフでは１次側と２次側の熱損失の合計をプロットしている。 In other words, if the active layer thickness is constant, the fewer the number of active layers, the greater the heat loss, as shown in Figure 8. The heat loss on the secondary side is also inversely proportional to the square of the number of active layers, and the graph plots the sum of the heat losses on the primary and secondary sides.
　一方、全長一定の場合、活性層数ｎの場合の電圧はＶ／ｎ、静電容量はＣ×ｎ２、巻き線比はＮ／ｎ倍となる。以上から熱損失Ｐは以下のようになる。
Ｉ１∝（Ｃ×ｎ２×Ｖ／ｎ×Ｎ／ｎ）
Ｐ∝（Ｃ×ｎ２×Ｖ／ｎ×Ｎ／ｎ）２
Ｐ∝（Ｃ・Ｖ・Ｎ）２ On the other hand, when the total length is constant, and the number of active layers is n, the voltage is V/n, the capacitance is C×n 2 , and the winding ratio is N/n. From the above, the heat loss P is calculated as follows:
I1 ∝(C× n2 ×V/n×N/n)
P ∝ (C × n 2 × V / n × N / n) 2
P ∝ (C V N) 2
　つまり全長一定の場合、活性層数に関係なく、熱損失は一定と値となる。これは２次側の熱損失も同様である。よって積層圧電素子３の全長を一定にすることで振動波モータの効率を保ったまま積層数を低減することが可能となり、内部電極の使用量低減により製造コストに低減が可能となる。 In other words, if the overall length is constant, the heat loss will be a constant value regardless of the number of active layers. The same applies to the heat loss on the secondary side. Therefore, by keeping the overall length of the laminated piezoelectric element 3 constant, it is possible to reduce the number of layers while maintaining the efficiency of the vibration wave motor, and by reducing the amount of internal electrodes used, it is possible to reduce manufacturing costs.
　ここで本発明の効果を発揮するのに適切な活性層数と厚みの関係を図９に示す。活性層３－１の厚みが薄いと前述のとおり静電容量が大きくなり回路損失が増大するので０．２６ｍｍ以上が好ましい（図９破線Ａ）。一方で厚すぎると分極が困難になるので１．００ｍｍ以下であることが好ましい（図９破線Ｂ）。また積層圧電素子３の活性層３－１の厚みをｔ１、層数をｎとした時、ｎ×ｔ１は１．０７ｍｍ以上（図９破線Ｃ）、３．０３ｍｍ以下（図９破線Ｄ）が好ましい。これは積層圧電素子３の全長が小さすぎても大きすぎて振動体の振動形状が所望のものと乖離していき、モータの駆動効率が低下するためである。また活性層数は２層よりも小さいと印可電圧が昇圧できる限界を超えるので２以上が好ましい（図９破線Ｅ）。このように活性層数と静電容量の関係を破線Ａ～Ｅで囲まれた領域（図９斜線部）に設定することで、内部電極の使用量低減により製造コストに低減と良好なモータ効率の両立を図ることが可能となる。 The relationship between the number of active layers and thickness suitable for achieving the effects of the present invention is shown in FIG. 9. If the thickness of the active layer 3-1 is thin, as mentioned above, the capacitance increases and the circuit loss increases, so it is preferable that it is 0.26 mm or more (dashed line A in FIG. 9). On the other hand, if it is too thick, polarization becomes difficult, so it is preferable that it is 1.00 mm or less (dashed line B in FIG. 9). Furthermore, when the thickness of the active layer 3-1 of the laminated piezoelectric element 3 is t1 and the number of layers is n, it is preferable that n×t1 is 1.07 mm or more (dashed line C in FIG. 9) and 3.03 mm or less (dashed line D in FIG. 9). This is because the total length of the laminated piezoelectric element 3 is too small or too large, and the vibration shape of the vibrating body deviates from the desired one, and the driving efficiency of the motor decreases. Furthermore, if the number of active layers is less than two layers, it exceeds the limit that the applied voltage can be increased, so it is preferable that it is 2 or more (dashed line E in FIG. 9). In this way, by setting the relationship between the number of active layers and the capacitance in the area enclosed by dashed lines A to E (shaded area in Figure 9), it is possible to achieve both reduced manufacturing costs and good motor efficiency by reducing the amount of internal electrodes used.
　活性層数について電極使用量の観点で２層以上、４層以下がより好ましく、２層場合の積層圧電素子３の構成を図１０Ａ、図１０Ｂに示す。ここでは活性層数が２、厚みが０．９ｍｍとしている。これにより、電極使用量を最小化することが可能となる。 From the viewpoint of electrode usage, it is preferable that the number of active layers is two or more and four or less. The configuration of a laminated piezoelectric element 3 with two layers is shown in Figures 10A and 10B. Here, the number of active layers is two and the thickness is 0.9 mm. This makes it possible to minimize the amount of electrodes used.
　なお、どの例においても不活性層３－２の厚みをｔ２、積層圧電素子３の全長（総厚み）をＴとするとＴ≧３０×ｔ２また、ｔ１≧２×ｔ２を満たすことが好ましい。これは不活性層３－２が厚いと振動波モータの軸方向のサイズの増大と、振動の阻害を引き起こすためである。 In any example, it is preferable that T ≥ 30 x t2 and t1 ≥ 2 x t2 be satisfied, where t2 is the thickness of the inactive layer 3-2 and T is the overall length (total thickness) of the laminated piezoelectric element 3. This is because if the inactive layer 3-2 is thick, it will increase the axial size of the vibration wave motor and cause vibration inhibition.
　本実施例の適切な静電容量の範囲について図１１を用いながら説明する。振動波モータの構成は実施例１と同様のため説明を省略する。静電容量をＣとして、このＣの単位はｎＦとすると、前記活性層の層数をｎとしたとき、０．０５ｎ２　ｎＦ（図１１破線Ｇ）≦Ｃ≦０．１４ｎ２　ｎＦ（図１１破線Ｆ）満たすことが好ましい。 The appropriate range of capacitance in this embodiment will be described with reference to Fig. 11. The configuration of the vibration wave motor is the same as that in the first embodiment, so the description will be omitted. If the capacitance is C and the unit of C is nF, and the number of layers of the active layer is n, it is preferable that 0.05n2nF (dashed line G in Fig. 11) ≦ C ≦ 0.14n2nF (dashed line F in Fig. 11) is satisfied.
　これは活性層数に対して容量が小さすぎると発生する力が小さくなってしまい、大きすぎると前述のように回路損失が大きくなってしまうからである。また活性層数は実施例２と同様に２以上（図１１破線Ｅ）、電極使用量削減の観点から１４層以下が望ましい（図１１破線Ｈ）。 This is because if the capacity is too small compared to the number of active layers, the generated force will be small, and if it is too large, the circuit loss will be large as mentioned above. The number of active layers should be 2 or more, as in Example 2 (Dotted line E in Figure 11), and 14 layers or less is desirable from the viewpoint of reducing the amount of electrodes used (Dotted line H in Figure 11).
　このように活性層数と静電容量の関係は破線Ｅ～Ｈに囲まれた斜線部内に設定することで、内部電極の使用量低減により製造コストに低減と良好なモータ効率の両立を図ることが可能となる。 In this way, by setting the relationship between the number of active layers and capacitance within the shaded area surrounded by dashed lines E to H, it is possible to achieve both reduced manufacturing costs and good motor efficiency by reducing the amount of internal electrodes used.
　振動波駆動装置は、例えば、撮像装置（光学機器、電子機器）のレンズ駆動用途等に用いることができる。そこで、一例として、レンズ鏡筒に配置されたレンズの駆動に振動波駆動装置を用いた撮像装置について説明する。 The vibration wave driving device can be used, for example, for driving lenses in imaging devices (optical devices, electronic devices). As an example, we will now explain an imaging device that uses a vibration wave driving device to drive a lens arranged in a lens barrel.
　図１２Ａは、撮像装置７００の概略構成を示す上面図である。撮像装置７００は、撮像素子７１０及び電源ボタン７２０を搭載したカメラ本体７３０を備える。また、撮像装置７００は、第１レンズ群（不図示）、第２レンズ群３２０、第３レンズ群（不図示）、第４レンズ群３４０、振動型駆動装置６２０，６４０を有するレンズ鏡筒７４０を備える。レンズ鏡筒７４０は、交換レンズとして取り換え可能であり、撮影対象に合わせて適したレンズ鏡筒７４０をカメラ本体７３０に取り付けることができる。撮像装置７００では、２つの振動型駆動装置６２０，６４０によってそれぞれ、第２レンズ群３２０，第４レンズ群３４０の駆動が行われる。 FIG. 12A is a top view showing the schematic configuration of the imaging device 700. The imaging device 700 includes a camera body 730 equipped with an imaging element 710 and a power button 720. The imaging device 700 also includes a lens barrel 740 having a first lens group (not shown), a second lens group 320, a third lens group (not shown), a fourth lens group 340, and vibration type drive devices 620 and 640. The lens barrel 740 is replaceable as an interchangeable lens, and a lens barrel 740 suitable for the subject to be photographed can be attached to the camera body 730. In the imaging device 700, the second lens group 320 and the fourth lens group 340 are driven by the two vibration type drive devices 620 and 640, respectively.
　振動型駆動装置６２０の詳細な構成は不図示であるが、振動型駆動装置６２０は、振動波駆動装置と、振動波駆動装置の駆動回路を有する。接触部７とロータ本環８で構成されるロータ２１１は、ラジアル方向が光軸と略直交するように、レンズ鏡筒７４０内に配置される。振動型駆動装置６２０では、ロータ２１１を光軸回りに回転させ、不図示のギア等を介して接触体の回転出力を光軸方向での直進運動に変換することによって、第２レンズ群３２０を光軸方向に移動させる。振動型駆動装置６４０は、振動型駆動装置６２０と同様の構成を有することにより、第４レンズ群３４０を光軸方向に移動させる。 The detailed configuration of the vibration type driving device 620 is not shown, but the vibration type driving device 620 has a vibration wave driving device and a driving circuit for the vibration wave driving device. The rotor 211, which is composed of the contact portion 7 and the rotor main ring 8, is arranged inside the lens barrel 740 so that the radial direction is approximately perpendicular to the optical axis. In the vibration type driving device 620, the rotor 211 is rotated around the optical axis, and the rotational output of the contact body is converted into linear motion in the optical axis direction via gears (not shown), thereby moving the second lens group 320 in the optical axis direction. The vibration type driving device 640 has a configuration similar to that of the vibration type driving device 620, and moves the fourth lens group 340 in the optical axis direction.
　図１２Ｂは、撮像装置７００の概略構成を示すブロック図である。第１レンズ群３ａ０、第２レンズ群３２０、第３レンズ群３３０、第４レンズ群３４０及び光量調節ユニット３５０が、レンズ鏡筒７４０内部の光軸上の所定位置に配置される。第１レンズ群３ａ０～第４レンズ群３４０と光量調節ユニット３５０とを通過した光は、撮像素子７１０に結像する。撮像素子７１０は、光学像を電気信号に変換して出力し、その出力は、カメラ処理回路７５０へ送られる。 FIG. 12B is a block diagram showing the schematic configuration of the imaging device 700. The first lens group 3a0, the second lens group 320, the third lens group 330, the fourth lens group 340, and the light amount adjustment unit 350 are arranged at predetermined positions on the optical axis inside the lens barrel 740. Light that passes through the first lens group 3a0 to the fourth lens group 340 and the light amount adjustment unit 350 forms an image on the imaging element 710. The imaging element 710 converts the optical image into an electrical signal and outputs it, and the output is sent to the camera processing circuit 750.
　カメラ処理回路７５０は、撮像素子７１０からの出力信号に対して増幅やガンマ補正等を施す。カメラ処理回路７５０は、ＡＥゲート７５５を介してＣＰＵ７９０に接続されると共に、ＡＦゲート７６０とＡＦ信号処理回路７６５とを介してＣＰＵ７９０に接続されている。カメラ処理回路７５０において所定の処理が施された映像信号は、ＡＥゲート７５５と、ＡＦゲート７６０及びＡＦ信号処理回路７６５を通じてＣＰＵ７９０へ送られる。なお、ＡＦ信号処理回路７６５は、映像信号の高周波成分を抽出して、オートフォーカス（ＡＦ）のための評価値信号を生成し、生成した評価値をＣＰＵ７９０へ供給する。 The camera processing circuit 750 performs amplification, gamma correction, etc. on the output signal from the image sensor 710. The camera processing circuit 750 is connected to the CPU 790 via an AE gate 755, and is also connected to the CPU 790 via an AF gate 760 and an AF signal processing circuit 765. The video signal that has been subjected to a predetermined process in the camera processing circuit 750 is sent to the CPU 790 via the AE gate 755, AF gate 760, and AF signal processing circuit 765. The AF signal processing circuit 765 extracts high frequency components from the video signal to generate an evaluation value signal for autofocus (AF), and supplies the generated evaluation value to the CPU 790.
　ＣＰＵ７９０は、撮像装置７００の全体的な動作を制御する制御回路であり、取得した映像信号から、露出決定やピント合わせのための制御信号を生成する。ＣＰＵ７９０は、決定した露出と適切なフォーカス状態が得られるように、振動型駆動装置６２０，６４０及びメータ６３０の駆動を制御することによって、第２レンズ群３２０、第４レンズ群３４０及び光量調節ユニット３５０の光軸方向位置を調整する。ＣＰＵ７９０による制御下において、振動型駆動装置６２０は第２レンズ群３２０を光軸方向に移動させ、振動型駆動装置６４０は第４レンズ群３４０を光軸方向に移動させ、光量調節ユニット３５０はメータ６３０により駆動制御される。 The CPU 790 is a control circuit that controls the overall operation of the imaging device 700, and generates control signals for determining exposure and adjusting focus from the acquired video signal. The CPU 790 adjusts the optical axis positions of the second lens group 320, the fourth lens group 340, and the light amount adjustment unit 350 by controlling the driving of the vibration type driving devices 620, 640 and the meter 630 so as to obtain the determined exposure and appropriate focus state. Under the control of the CPU 790, the vibration type driving device 620 moves the second lens group 320 in the optical axis direction, the vibration type driving device 640 moves the fourth lens group 340 in the optical axis direction, and the light amount adjustment unit 350 is driven and controlled by the meter 630.
　振動型駆動装置６２０により駆動される第２レンズ群３２０の光軸方向位置は第１リニアエンコーダ７７０により検出され、検出結果がＣＰＵ７９０に通知されることで、振動型駆動装置６２０の駆動にフィードバックされる。同様に、振動型駆動装置６４０により駆動される第４レンズ群３４０の光軸方向位置は第２リニアエンコーダ７７５により検出され、検出結果がＣＰＵ７９０に通知されることで、振動型駆動装置６４０の駆動にフィードバックされる。光量調節ユニット３５０の光軸方向位置は、絞りエンコーダ７８０により検出され、検出結果がＣＰＵ７９０へ通知されることで、メータ６３０の駆動にフィードバックされる。 The optical axis direction position of the second lens group 320 driven by the vibration type driving device 620 is detected by a first linear encoder 770, and the detection result is notified to the CPU 790, which feeds back the drive of the vibration type driving device 620. Similarly, the optical axis direction position of the fourth lens group 340 driven by the vibration type driving device 640 is detected by a second linear encoder 775, and the detection result is notified to the CPU 790, which feeds back the drive of the vibration type driving device 640. The optical axis direction position of the light amount adjustment unit 350 is detected by an aperture encoder 780, and the detection result is notified to the CPU 790, which feeds back the drive of the meter 630.
　本発明は上記実施の形態に制限されるものではなく、本発明の精神及び範囲から離脱することなく、様々な変更及び変形が可能である。従って、本発明の範囲を公にするために、以下の請求項を添付する。 The present invention is not limited to the above-described embodiment, and various modifications and variations are possible without departing from the spirit and scope of the present invention. Therefore, in order to publicize the scope of the present invention, the following claims are appended.
　本願は、２０２２年１１月１４日提出の日本国特許出願特願２０２２－１８２０４６を基礎として優先権を主張するものであり、その記載内容の全てを、ここに援用する。 This application claims priority based on Japanese Patent Application No. 2022-182046, filed on November 14, 2022, the entire contents of which are incorporated herein by reference.
　１　第１の弾性体
　２　第２の弾性体
　３　積層圧電素子
　３－１　活性層
　３－２　不活性層
　３－３　電極層
　４　フレキシブルプリント基板
　５　シャフト
　６　ナット
　７　接触部
　８　ロータ本環
　９　ゴム
　１０　加圧バネ
　１１　ギア
　１２　フランジキャップ
　１３　フランジ
　１４　上ナット
　１５　振動体 REFERENCE SIGNS LIST 1 First elastic body 2 Second elastic body 3 Multilayer piezoelectric element 3-1 Active layer 3-2 Inactive layer 3-3 Electrode layer 4 Flexible printed circuit board 5 Shaft 6 Nut 7 Contact portion 8 Rotor main ring 9 Rubber 10 Pressure spring 11 Gear 12 Flange cap 13 Flange 14 Upper nut 15 Vibration body

Claims (8)

  1. 　第１の弾性体と、第２の弾性体と、前記第１の弾性体と前期第２の弾性体に挟持された電気－機械エネルギー変換素子とを有する振動体と、
    　前記第１の弾性体に接触する接触体と、を備え、
    　前記電気－機械エネルギー変換素子に電圧を印加することで、前記振動体に前記第１の弾性体の中心軸と直交する方向に変位する２つの曲げ振動モードを励振することで、前記接触体を前記中心軸周りに回転させる振動波モータにおいて、
    　前記電気－機械エネルギー変換素子は、分極された圧電体である活性層と、電極層が交互に積層された構成であり、
    　前記活性層は２層以上、前記電極層は３層以上であり、
    　前記活性層の厚みをｔ１としたとき、０．２６ｍｍ≦ｔ１≦１．００ｍｍを満たすことを特徴とする振動波モータ。     a vibrator having a first elastic body, a second elastic body, and an electromechanical energy conversion element sandwiched between the first elastic body and the second elastic body;
    a contact body that contacts the first elastic body,
    a vibration wave motor that rotates the contact body around the central axis by exciting the vibrator in two bending vibration modes that displace in a direction perpendicular to the central axis of the first elastic body by applying a voltage to the electromechanical energy conversion element,
    The electromechanical energy conversion element has a structure in which an active layer, which is a polarized piezoelectric body, and an electrode layer are alternately laminated,
    The active layer has two or more layers, and the electrode layer has three or more layers,
    A vibration wave motor, wherein when the thickness of the active layer is t1, 0.26 mm≦t1≦1.00 mm is satisfied.
  2. 　前記活性層の層数をｎとしたとき、１．０７ｍｍ≦ｎ×ｔ１≦３．０３ｍｍを満たすことを特徴とする請求項１に記載の振動波モータ。 The vibration wave motor according to claim 1, characterized in that, when the number of layers of the active layer is n, 1.07 mm≦n×t1≦3.03 mm is satisfied.
  3. 　前記電気－機械エネルギー変換素子の最上層と最下層には分極されていない圧電体である不活性層が配されており、前記不活性層の厚みをｔ２としたとき、ｔ１≧２×ｔ２を満たすことを特徴とする請求項１または２に記載の振動波モータ。 The vibration wave motor according to claim 1 or 2, characterized in that the uppermost and lowermost layers of the electromechanical energy conversion element are inactive layers that are non-polarized piezoelectric bodies, and when the thickness of the inactive layers is t2, t1 ≥ 2 × t2 is satisfied.
  4. 　前記電気－機械エネルギー変換素子の総厚みをＴとしたとき、Ｔ≧３０×ｔ２を満たすことを特徴とする請求項１または２に記載の振動波モータ。 The vibration wave motor according to claim 1 or 2, characterized in that, when the total thickness of the electromechanical energy conversion element is T, T≧30×t2 is satisfied.
  5. 　前記活性層の層数の２層以上であり４層以下であることを特徴とする請求項１または２に記載の振動波モータ。 The vibration wave motor according to claim 1 or 2, characterized in that the number of layers of the active layer is 2 or more and 4 or less.
  6. 　第１の弾性体と第２の弾性体と、前記第１の弾性体と前期第２の弾性体に挟持された電気－機械エネルギー変換素子とを有する振動体と、
    　前記第１の弾性体に接する接触体と、を備え、
    　前記電気－機械エネルギー変換素子に電圧を印可することで、前記振動体に前記第１の弾性体の中心軸と直交する方向に変位する２つの曲げ振動モードを励振することで、前記接触体を前記中心軸周りに回転させる振動波モータにおいて、
    　前記電気－機械エネルギー変換素子は分極された圧電体である活性層と、電極層が交互に積層された構成であり、
    　前記活性層は２層以上、前記電極層は３層以上であり、
    　前記電気－機械エネルギー変換素子の静電容量をＣ、前記活性層の層数をｎとしたとき、０．０５ｎ２　ｎＦ≦Ｃ≦０．１４ｎ２　ｎＦを満たすことを特徴とする振動波モータ。     a vibrating body having a first elastic body, a second elastic body, and an electromechanical energy conversion element sandwiched between the first elastic body and the second elastic body;
    a contact body that contacts the first elastic body,
    A vibration wave motor in which a voltage is applied to the electromechanical energy conversion element to excite the vibrator in two bending vibration modes in which the vibrator is displaced in a direction perpendicular to a central axis of the first elastic body, thereby rotating the contact body around the central axis,
    The electromechanical energy conversion element has a structure in which an active layer, which is a polarized piezoelectric body, and an electrode layer are alternately laminated,
    The active layer has two or more layers, and the electrode layer has three or more layers,
    A vibration wave motor, characterized in that, when the electrostatic capacitance of the electromechanical energy conversion element is C and the number of layers of the active layer is n, 0.05n 2 nF≦C≦0.14n 2 nF is satisfied.
  7. 　レンズと、
    　請求項１乃至６のいずれか１項記載の振動波モータを備えた光学機器。     Lenses and
    7. An optical device comprising the oscillatory wave motor according to claim 1.
  8. 　部材と、
    　前記部材を駆動する請求項１乃至７のいずれか１項記載の振動波モータを備えた電子機器。     The material,
    8. An electronic device comprising the vibration wave motor according to claim 1 for driving the member.
PCT/JP2023/038236 2022-11-14 2023-10-24 Vibration wave motor, optical device, and electronic device WO2024106146A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH078911A (en) * 1993-06-23 1995-01-13 Canon Inc Vibrator and ultrasonic motor
JPH07163163A (en) * 1993-12-01 1995-06-23 Canon Inc Ultrasonic oscillator
JP2004180416A (en) * 2002-11-27 2004-06-24 Canon Inc Vibrator and vibration wave driver
JP2012199570A (en) * 2012-05-28 2012-10-18 Canon Inc Manufacturing method of laminated piezoelectric element

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH078911A (en) * 1993-06-23 1995-01-13 Canon Inc Vibrator and ultrasonic motor
JPH07163163A (en) * 1993-12-01 1995-06-23 Canon Inc Ultrasonic oscillator
JP2004180416A (en) * 2002-11-27 2004-06-24 Canon Inc Vibrator and vibration wave driver
JP2012199570A (en) * 2012-05-28 2012-10-18 Canon Inc Manufacturing method of laminated piezoelectric element

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