JPH099656A - Ultrasonic vibrator and ultrasonic motor - Google Patents

Abstract

PURPOSE: To provide an ultrasonic vibrator having a simple configuration, permitting low voltage drive and a node position for longitudinal vibration aligned with the node position of torsional vibration. CONSTITUTION: An ultrasonic vibrator is provided with a columnar elastic body 11 having a plurality of grooves 12 and 13 at predetermined positions on the outer periphery, a plurality of laminated type piezoelectric elements 14 arranged in a slanted state on at least two facing sides of the columnar elastic body 11, and a sliding friction element 18 bonded to the end face of the columnar elastic body 11; and by applying alternating voltages with different phases respectively to a plurality of laminated type piezoelectric elements 14, a resonant longitudinal vibration and a resonant torsional vibration can be excited at the same time, thereby generating an ultrasonic elliptical vibration on the surface of the sliding friction element 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic vibrator using an electromechanical conversion element as a drive source and an ultrasonic motor using the ultrasonic vibrator.

[0002]

2. Description of the Related Art In recent years, an ultrasonic motor has attracted attention as a new motor replacing an electromagnetic motor. This ultrasonic motor has the following advantages over a conventional electromagnetic motor. (1) Low rotation and high torque can be obtained without gears. (2) Large holding force. (3) High resolution. (4) It is extremely quiet. (5) Magnetic noise is not generated, and the influence of noise is not exerted.

As one of conventional ultrasonic motors, there is an ultrasonic motor utilizing longitudinal torsional vibration disclosed in "New Actuator Handbook for Precision Control p897 (Fuji Techno System)". This conventional ultrasonic motor will be described with reference to FIGS. 14 and 15. FIG. 9 is a front view of a longitudinal torsion ultrasonic motor, and FIG. 10 is an explanatory view of the principle of exciting ultrasonic elliptical vibration in an ultrasonic vibrator.

In FIG. 14, the longitudinal torsion ultrasonic motor is
A cylindrical vibrator 10 mainly having a diameter of 20 mm and a length of 43 mm
1, and a rotor 102 having a diameter of 20 mm and a length of 12 mm,
It is composed of a pressing member 103 such as a spring. Vibrator 1
Reference numeral 01 denotes an elastic body 104 having a groove 104a provided at a predetermined position on the outer periphery thereof, an annular piezoelectric ceramics 105 for longitudinal vibration excitation, and a piezoelectric ceramics 106 for torsional vibration excitation.
It is composed of an elastic body 107 that holds them.
By applying an alternating voltage having a resonance frequency with a phase difference to the piezoelectric ceramics 105 for exciting longitudinal vibration and the piezoelectric ceramics 106 for exciting torsional vibration, the vibrator 1
The ultrasonic elliptical vibration for rotating the rotor 102 in the clockwise or counterclockwise direction is excited in the portion of No. 01 in contact with the rotor 102.

Next, the principle that ultrasonic elliptical vibration is excited in the vibrator will be described. As shown in FIGS. 15 (a) and 15 (b), the longitudinal vibration mode and the torsional vibration mode are degenerated, both modes are excited at substantially the same frequency, and ultrasonic elliptical vibration is to be generated on the end surface. for that purpose,
Since a simple cylindrical vibrator cannot degenerate the longitudinal vibration mode and the torsional vibration mode, a groove is provided at a predetermined position on the outer circumference of the elastic body. By providing this groove with an appropriate depth and width at an appropriate position, the longitudinal vibration mode and the torsional vibration mode can be degenerated.

[0006]

However, the above-mentioned conventional ultrasonic motor has the following problems. (1) Since two types of piezoelectric vibrators, that is, an annular piezoelectric ceramic for longitudinal vibration excitation and an annular piezoelectric ceramic for torsional vibration are required, the configuration becomes complicated. (2) Since the node position of longitudinal vibration and the node position of torsional vibration are different, the annular piezoelectric ceramics for longitudinal vibration excitation and the annular piezoelectric ceramics for torsional vibration excitation are arranged at the respective node positions. There must be.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the invention according to claim 1 or 2 is that the structure is simple, low voltage driving is possible, and a node of longitudinal vibration is present. An object is to provide an ultrasonic transducer in which the position and the node position of torsional vibration are the same. An object of the invention according to claim 3 is to provide an ultrasonic motor having a simple structure and capable of being driven at a low voltage. An object of the invention according to claim 4 or 5 is to provide an ultrasonic transducer having a simple structure, in which the node position of longitudinal vibration and the node position of torsional vibration are the same. An object of the invention according to claim 6 is to provide an ultrasonic motor having a simple structure.

[0008]

In order to solve the above-mentioned problems, the invention according to claim 1 or 2 is, in an ultrasonic transducer, a columnar elastic body having a plurality of grooves at predetermined positions on the outer periphery, A plurality of laminated piezoelectric elements provided inclined to at least two opposing side surfaces of the columnar elastic body, and a sliding friction element joined to an end surface of the columnar elastic body are provided. By applying alternating voltages having different phases, resonant longitudinal vibration and resonant torsional vibration are simultaneously excited, and ultrasonic elliptical vibration is generated on the surface of the sliding friction element. According to a third aspect of the present invention, in the ultrasonic motor, a shaft is provided upright in the center of the surface of the sliding friction element of the ultrasonic vibrator according to the first or second aspect, and a rotor is fitted on the shaft, The rotor is pressed and held by the sliding friction element. The invention according to claim 4 or 5 is characterized in that a columnar elastic body having a plurality of grooves at predetermined positions on the outer periphery thereof, and a plurality of interdigitated electrode piezoelectric elements provided obliquely on at least two opposing side surfaces of the columnar elastic body. A plate and a sliding friction member joined to the end face of the columnar elastic body,
By applying alternating voltages having different phases to the plurality of interdigital electrode piezoelectric plates, resonance longitudinal vibration and resonance torsional vibration are excited at the same time, and ultrasonic elliptical vibration is generated on the surface of the sliding friction element. It is characterized in that it is configured in.
According to a sixth aspect of the present invention, in an ultrasonic motor, a shaft is erected at the center of the surface of the sliding friction element of the ultrasonic vibrator according to the fourth or fifth aspect, and a rotor is fitted on the shaft, The rotor is pressed and held by the sliding friction element.

[0009]

In the operation of the invention according to claim 1 or 2, resonance longitudinal vibration can be excited by applying voltages of the same phase to the pair of laminated piezoelectric elements. Further, when a voltage of opposite phase is applied to the pair of laminated piezoelectric elements, resonance torsional vibration can be excited. Further, when voltages having a phase difference of π / 2 are applied to the pair of laminated piezoelectric elements, resonance longitudinal vibration and resonance torsional vibration are simultaneously excited, and ultrasonic elliptical vibration is synthesized at the position of the sliding friction element. In the operation of the invention according to claim 3,
Alternatively, when the rotor is pressed against the portion where the ultrasonic elliptical vibration is excited by the action of the invention according to the second aspect, the rotor is rotationally driven clockwise or counterclockwise according to the vibration direction of the ultrasonic elliptical vibration.

In the operation of the invention according to claim 4 or 5,
When the same phase voltage is applied to the pair of cross finger electrode piezoelectric plates,
Resonant longitudinal vibration can be excited. In addition, when a voltage of opposite phase is applied to the pair of interdigital transducer piezoelectric plates, resonance torsional vibration can be excited. Furthermore, the phase is π / 2 on the pair of interdigitated electrode piezoelectric plates.
When different voltages are applied, resonance longitudinal vibration and resonance torsional vibration are simultaneously excited, and ultrasonic elliptical vibration is synthesized at the position of the sliding friction element. In the operation of the invention according to claim 6, when the rotor is pressed against the portion where the ultrasonic elliptical vibration is excited by the operation of the invention according to claim 4 or 5, the rotor is moved in accordance with the vibration direction of the ultrasonic elliptical vibration. It is driven to rotate clockwise or counterclockwise.

[0011]

Embodiment 1 FIGS. 1 to 8 show Embodiment 1, FIG. 1 is a front view of an ultrasonic vibrator, FIG. 2 is a rear view of the ultrasonic vibrator, and FIG.
Is a left side view of the ultrasonic oscillator, FIG. 4 is a right side view of the ultrasonic oscillator, FIG. 5 is a top view of the ultrasonic oscillator, and FIG. 6 is an explanatory diagram showing displacement between resonant longitudinal vibration and resonant torsional vibration. 7 is a front view of the ultrasonic motor, and FIG. 8 is an exploded view of the ultrasonic motor.

1 to 5, reference numeral 10 denotes an ultrasonic transducer. The basic elastic body 11 is a brass material (O of C2801P).
Material) in the shape of a prism, almost 9 mm x 9 mm x 4
It has a size of 0 mm, and is located at almost the same position 2 from both end faces.
Grooves 12 and 13 each having a depth of about 2 mm are recessed at the points along the entire circumference. The laminated piezoelectric element 14 is sandwiched between the front surface and the back surface of the basic elastic body 11 at a constant inclination angle, and a projection portion 15 having an inclined surface formed integrally with the basic elastic body 15 is formed.
In addition, the elastic body 16 for holding is held and fixed while a compressive force of about 100 N is applied. The elastic body 16 for holding is
It is screwed onto the basic elastic body 11 with screws 17. Further, the laminated piezoelectric element 14 and the holding elastic body 16 are more firmly fixed to the basic elastic body 11 by using an epoxy adhesive.

The laminated piezoelectric element 14 has a size of 2 mm ×
It has a size of 3.1 mm × 9 mm, and the front surface (FIG. 1) and the back surface (FIG. 2) form an acute angle in the opposite direction when facing each other, and are attached so as to be inclined. Therefore, as shown in FIGS. 3 and 4, the side surface of the laminated piezoelectric element 13 is projected at the same position in the vertical direction on both the front and back surfaces. Further, the electric terminals output from the respective laminated piezoelectric elements 14 are respectively A
A terminal, a GND terminal, a B terminal, and a GND terminal.

At the tip of the basic elastic body 11, there is joined a sliding friction element 18 made of a grindstone in which abrasive grains of alumina ceramic are dispersed in an annular phenol resin. A through hole 19 is bored on the central axis of the basic elastic body 11, and a female screw (not shown) is screwed at approximately the center of the central axis.

Next, the operation of the ultrasonic transducer 10 will be described. The ultrasonic transducer 10 has dimensions such that resonance longitudinal vibration (a vibration displacement is shown in FIG. 6A) and resonance torsional vibration (a vibration displacement is shown in FIG. 2B) having a node portion at one place. It can be excited at almost the same frequency Fr (40 kHz). However, in the resonance torsional vibration, the central axis portion in the longitudinal direction of the basic elastic body 11 is all fixed points or nodes.

First, the terminal A has an amplitude of 30 Vp at a frequency Fr.
When an alternating voltage of −p was applied and an alternating voltage of the same frequency, the same amplitude and the same phase was applied to the B terminal, resonance longitudinal vibration was excited. Next, when an alternating voltage with an amplitude of 30 Vp-p with a frequency Fr is applied to the A terminal and an alternating voltage with the same frequency and the same amplitude and an opposite phase is applied to the B terminal, resonance torsional vibration is excited.
Further, an alternating voltage having an amplitude of 30 Vp-p with a frequency Fr is applied to the A terminal, and the same frequency with the same amplitude and a phase of 9 is applied to the B terminal.
When alternating voltages different from each other by 0 degree were applied, the resonance longitudinal vibration and the resonance torsional vibration were combined, and the elliptical vibration was excited at the position of the sliding friction element 16.

Next, the ultrasonic motor 50 of this embodiment using the ultrasonic vibrator 10 will be described with reference to FIGS. In FIGS. 7 and 8, a shaft 51 is fitted in the through hole 19 (see FIG. 5) of the ultrasonic transducer 10.
As shown in FIG. 8, the shaft 51 has a male thread 58 threaded on the central portion and both end portions thereof. The male thread 58 at the central portion is screwed onto a female thread (not shown) of the ultrasonic transducer 10 and then adhesively fixed. Has been done. At the upper end of the ultrasonic transducer 10, the rotor 53 is provided with the thrust bearing 54 and the spring holding member 5.
It is pressed and fixed by a spring 56 through 5. The pressing force is adjusted by the nut 57. Annular rotor 53
A sliding plate 52 made of an annular zirconia ceramic is attached to the lower surface of the. When fixing the ultrasonic motor 50, the male screw 58 of the shaft 51 protruding below the ultrasonic motor 50 is fixed.
Is screwed and fixed to a base (not shown).

As indicated above, the A of the ultrasonic transducer 10
A frequency of 40 kHz and an amplitude of 30 Vp-
Alternating voltage of p, phase difference +90 degrees or -90 degrees is applied. Then, the rotor 53 rotates clockwise or counterclockwise.

According to this embodiment, a common node for longitudinal vibration and torsional vibration can be formed in the substantially central portion of the basic elastic body, and since the laminated piezoelectric element is arranged at that position, longitudinal vibration and torsional vibration are eliminated. It can be excited efficiently. Further, since the laminated piezoelectric element is used as the drive source, the drive voltage can be lowered. Further, since the laminated piezoelectric element is assembled in a state in which a compressive force is applied, the piezoelectric element is not broken and the life can be greatly extended. Further, one type of piezoelectric element can be used to excite longitudinal vibration and torsional vibration, and the structure is simple, so that it can be manufactured at low cost. Further, since the ultrasonic motor using this ultrasonic oscillator holds the vibration at a common node position for longitudinal vibration and torsional vibration, there is little vibration leakage and high efficiency.

In this embodiment, a prismatic columnar body is used as the basic elastic body, but a cylindrical columnar body may be partially cut to fix the laminated piezoelectric element. Further, in this embodiment, two laminated piezoelectric elements are used, but a structure in which four piezoelectric elements are fixed to each of the four side surfaces may be used. Furthermore, in the present embodiment, the groove is provided at two places over the entire circumference, but it may be provided at three or more places without departing from the gist of the present invention.

[0021]

Second Embodiment FIGS. 9 to 13 show a second embodiment, FIG. 9 is a front view of an ultrasonic vibrator, FIG. 10 is a rear view of the ultrasonic vibrator,
11 is a right side view of the ultrasonic transducer, FIG. 12 is a left side view of the ultrasonic transducer, and FIG. 13 is a top view of the ultrasonic transducer.
The present embodiment is different from the first embodiment only in the configuration of the ultrasonic transducer, and the configuration of the ultrasonic motor is the same as that of the first embodiment, and therefore, illustration and description thereof are omitted.

9 to 13, an ultrasonic transducer 70
Uses a cross finger electrode piezoelectric plate 72 instead of the laminated piezoelectric element as the drive source in the first embodiment. The interdigital electrode piezoelectric plate 72 is polarized in a direction substantially perpendicular to the thickness direction of the plate, and operates by the piezoelectric vertical effect. The interdigital electrode piezoelectric plate 72 has an interdigital pattern bonded and fixed with a certain acute angle with respect to the longitudinal direction of the basic elastic body 72.
The cross finger electrode piezoelectric plate 72 has a size of 8 mm (width) x 12 m.
m (length) × 1 mm (thickness), and the front surface (FIG. 9) and the back surface (FIG. 10) are mounted in the opposite directions when facing each other. Therefore, as shown in FIG. 11 and FIG.
The side surface of the interdigital electrode piezoelectric plate 72 is projected at the same position in the vertical direction on both the front and back surfaces. Further, the electric terminals output from the respective cross finger electrode piezoelectric plates 72 are respectively A
A terminal, a GND terminal, a B terminal, and a GND terminal. The shape and dimensions of the basic elastic body 71, the positions and sizes of the grooves 12 and 13, the sliding friction element 18 and the like are the same as in the first embodiment.

The operation of the ultrasonic transducer 70 and the operation of the ultrasonic motor using the interdigital transducer piezoelectric plate 70 are the same as those in the first embodiment, and the description thereof will be omitted.

According to the present embodiment, a common node for longitudinal vibration and torsional vibration can be formed in the substantially central portion of the basic elastic body, and since the cross finger electrode piezoelectric plate is arranged at that position, longitudinal vibration and torsional vibration are formed. Can be efficiently excited. Further, one type of piezoelectric element can be used to excite longitudinal vibration and torsional vibration, and the structure is simple, so that it can be manufactured at low cost. Further, since the ultrasonic motor using this ultrasonic oscillator holds the vibration at a common node position for longitudinal vibration and torsional vibration, there is little vibration leakage and high efficiency.

In the present embodiment, a prismatic columnar body is used as the basic elastic body, but a cylindrical columnar body may be partially cut to fix the cross finger electrode piezoelectric plates. Further, in the present embodiment, two piezoelectric finger plates for the interdigital electrodes are used, but a structure may be used in which four piezoelectric plates are fixed to each of the four side surfaces. Furthermore, in the present embodiment, the groove is provided at two places over the entire circumference, but it may be provided at three or more places without departing from the gist of the present invention.

[0026]

According to the first or second aspect of the present invention,
Since the structure is simple and low voltage driving is possible, the node position of longitudinal vibration and the node position of torsional vibration are the same,
It is possible to obtain an ultrasonic transducer in which efficient vibration is excited. According to the invention of claim 3, since the ultrasonic oscillator of the invention of claim 1 or 2 is used, it is possible to obtain a highly efficient ultrasonic motor which can be driven at a low voltage with a simple configuration. it can. According to the invention of claim 4 or 5,
Since the structure is simple and the node position of the longitudinal vibration is the same as the node position of the torsional vibration, it is possible to obtain an ultrasonic transducer in which efficient vibration is excited. According to the invention of claim 6, since the ultrasonic oscillator of the invention of claim 4 or 5 is used, a highly efficient ultrasonic motor can be obtained with a simple configuration.

[Brief description of drawings]

FIG. 1 is a front view of an ultrasonic transducer of Example 1.

FIG. 2 is a back view of the ultrasonic transducer of the first embodiment.

FIG. 3 is a left side view of the ultrasonic transducer of the first embodiment.

FIG. 4 is a right side view of the ultrasonic transducer according to the first embodiment.

FIG. 5 is a top view of the ultrasonic transducer of the first embodiment.

FIG. 6 is an explanatory diagram showing the displacement between the resonant longitudinal vibration and the resonant torsional vibration of the first embodiment.

FIG. 7 is a front view of the ultrasonic motor according to the first embodiment.

FIG. 8 is an exploded view of the ultrasonic motor according to the first embodiment.

FIG. 9 is a front view of the ultrasonic transducer of the second embodiment.

FIG. 10 is a back view of the ultrasonic transducer of the second embodiment.

FIG. 11 is a right side view of the ultrasonic transducer according to the second embodiment.

FIG. 12 is a left side view of the ultrasonic transducer of the second embodiment.

FIG. 13 is a top view of the ultrasonic transducer of the second embodiment.

FIG. 14 is a front view of a conventional vertical-screw ultrasonic motor.

FIG. 15 is an explanatory diagram of a principle in which ultrasonic elliptical vibration is excited in a conventional ultrasonic transducer.

[Explanation of symbols]

 11 Basic Elastic Body 12 Groove 13 Groove 14 Multilayer Piezoelectric Element 16 Holding Elastic Body 18 Sliding Friction Element

Front page continued (72) Inventor Yoshihisa Taniguchi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd.

Claims (6)

[Claims] 1. A columnar elastic body having a plurality of grooves at predetermined positions on the outer periphery thereof, a plurality of laminated piezoelectric elements obliquely provided on at least two opposing side surfaces of the columnar elastic body, and the columnar elastic body. A sliding friction element bonded to the end face of the body, and by applying alternating voltages of different phases to the plurality of laminated piezoelectric elements, resonant longitudinal vibration and resonant torsional vibration are excited at the same time, and An ultrasonic transducer, characterized in that it is configured to generate ultrasonic elliptical vibrations on the surface of a friction element. 2. The plurality of grooves are provided one by one on both sides of the portion where the plurality of laminated piezoelectric elements are provided in the longitudinal direction of the columnar elastic body. Ultrasonic transducer. 3. An ultrasonic vibrator according to claim 1, wherein a shaft is provided upright in the center of the surface of the sliding friction element, and a rotor is fitted on the shaft, and the rotor is used as the sliding friction element. An ultrasonic motor characterized by being pressed and held. 4. A columnar elastic body having a plurality of grooves at predetermined positions on the outer periphery, a plurality of interdigitated electrode piezoelectric plates obliquely provided on at least two opposing side surfaces of the columnar elastic body, and the columnar body. A sliding friction element joined to the end surface of the elastic body, by applying alternating voltages having different phases to the plurality of interdigital electrode piezoelectric plates, the resonant longitudinal vibration and the resonant torsional vibration are excited at the same time, An ultrasonic transducer characterized in that it is configured to generate ultrasonic elliptical vibration on the surface of a sliding friction element. 5. The plurality of grooves are provided one by one on both sides of a portion of the columnar elastic body where the plurality of piezoelectric finger plates are provided in the longitudinal direction. Ultrasonic transducer. 6. An ultrasonic vibrator according to claim 4, wherein a shaft is provided upright in the center of the surface of the sliding friction element, a rotor is fitted on the shaft, and the rotor is used as the sliding friction element. An ultrasonic motor characterized by being pressed and held.