JPH02237478A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To simplify the structure by employing piezoelectric ceramic poles for piezoelectric longitudinal vibrator and piezoelectric torsional vibrator then printing electrodes on the outer circumferential faces thereof. CONSTITUTION:An ultrasonic motor comprises a piezoelectric torsional vibrator 1 and a piezoelectric longitudinal vibrator 103, where metallic poles 5, 6 are jointed to the opposite sides thereof in order to provide a Langevin longitudinal- torsional vibrator and a rotor 9 is supported rotatably on the shaft 7 at one end face through a bearing 8. Composite longitudinal-torsional vibration at the other end of the metallic pole 5 is converted into rotary motion of the rotor 9.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a so-called ultrasonic motor that uses ultrasonic vibration of a piezoelectric vibrator used in OA equipment, etc., and particularly relates to a so-called ultrasonic motor that uses ultrasonic vibration of a piezoelectric vibrator used in OA equipment, etc. Regarding ultrasonic motors.

[Conventional technology]

FIG. 9 is a perspective view of a structural example of a vertical single-torsion composite vibrator 101 used in a conventional vertical single-torsion vibrator type ultrasonic motor. Piezoelectric torsional vibrator 102 and piezoelectric longitudinal vibrator 103
are joined via a metal cylinder 4, and metal cylinders 5 and 6 are further joined to both sides of these. In this case, a metal cylinder can be used instead of the metal cylinder. FIG. 10 is a perspective view of a structural example of an ultrasonic motor configured using the vertical single-twist composite vibrator 101 shown in FIG. A hole reaching at least the vibration node is formed, and a shaft 7 smaller than the diameter of the hole is inserted into the hole and fixed to the composite vibrator 101 at the contact point. Further, a rotor 9 rotatably supported by a bearing 8 is pressed against the end face of the longitudinal single-torsion composite vibrator 101 by a coil spring 10 and a nut 11. FIG. 11 shows an example of the structure of the piezoelectric torsional vibrator shown in FIG. 9, and the disc-shaped piezoelectric torsional vibrator 102 is constructed by joining four fan-shaped piezoelectric ceramic plates 112. Each fan-shaped piezoelectric ceramic plate 112 is polarized in the direction of the chord of the fan, as shown in FIG. When applied, a sliding strain parallel to the plate thickness occurs in the fan-shaped piezoelectric ceramic plate.

When four sector-shaped piezoelectric ceramic plates 112 are joined in a disc shape, the sliding strain generated in each sector-shaped piezoelectric ceramic board is combined, resulting in torsional distortion that twists the top and bottom surfaces of the disc. Become.

In the conventional piezoelectric torsional vibrator shown in FIG. 11, as shown in FIG. A fan-shaped piezoelectric ceramic plate 112 polarized in the direction of the chord of the fan as shown in the figure.
, and then glue 4 pieces together to form a disk shape, or
As shown in Figure 4, regular square prisms 115 are cut out from a piezoelectric ceramic block 114 polarized in the thickness direction so that the polarization direction is in the diagonal direction, and four regular square prisms 115 are formed into a loop with the polarization direction closed. They are stacked and glued together so that the outer periphery is polished into a vibrator shape, and then cut into disc shapes.

Figure 15 shows an example of the structure of a conventional piezoelectric vertical vibrator, in which a voltage is applied to a piezoelectric ceramic disc 103 that has electrodes on both sides and is polarized in the thickness direction to obtain vibration in the thickness direction. . In order to obtain a large vibration amplitude with a low applied voltage, a plurality of thin piezoelectric ceramic discs 116 are laminated to form the 16th
It may also be configured as shown in 103' in the figure.

[Problems to be Solved by the Invention] Since the conventional piezoelectric torsional vibrator 102 shown in FIG. 11 is configured by bonding a plurality of piezoelectric ceramics, there are large variations in characteristics due to bonding. Also,
As shown in FIGS. 12, 13, and 14, the processing to obtain the piezoelectric torsional vibrator 102 is complicated and extremely expensive.

The technical problem of the present invention is to eliminate the drawbacks of the conventional ultrasonic motor using a piezoelectric torsional vibrator as described above, and to use a piezoelectric torsional vibrator that is easy to process, does not require a bonding process, and has little variation. Our purpose is to provide ultrasonic motors.

Another technical problem of the present invention is that by using a hollow piezoelectric longitudinal-torsional composite vibrator, two rotors are pressed against both ends of the piezoelectric vertical-torsional composite vibrator by means of a shaft penetrating the hollow part. An object of the present invention is to provide a two-rotor type ultrasonic motor.

[Means for Solving the Problems] According to the present invention, there is provided a piezoelectric torsional vibrator having a first cross-sectional shape orthogonal to a central axis and torsionally vibrating around the central axis, and one end of the torsional vibrator. a piezoelectric longitudinal vibrator disposed such that one end thereof is opposite to the piezoelectric longitudinal vibrator, the piezoelectric longitudinal vibrator having a second cross-sectional shape substantially equal to the first cross-sectional shape and performing stretching vibration in the direction of the central axis; and the piezoelectric torsional vibrator. a third one having one end joined to the other end and having a cross-sectional shape substantially equal to the first cross-sectional shape;
a first metal material having a cross-sectional shape of , and a second metal material having one end joined to the other end of the piezoelectric longitudinal vibrator and having a fourth cross-sectional shape substantially equal to the first cross-sectional shape. the piezoelectric torsional vibrator has a piezoelectric torsional vibrator having an outer circumferential surface; An ultrasonic wave device comprising a ceramic, and a plurality of first diagonal electrodes and a plurality of second diagonal electrodes arranged alternately on the outer peripheral surface in a direction intersecting the central axis of the piezoelectric ceramic. A motor is obtained.

[Function] The piezoelectric vertical single-torsion composite vibrator used in the ultrasonic motor of the present invention first includes a first and a first torsion composite vibrator on the outer periphery of a piezoelectric ceramic cylinder, preferably in a direction of 45@ with respect to the longitudinal direction of the piezoelectric ceramic. When the piezoelectric ceramic cylindrical vibrator is polarized using the two terminals, the direction of polarization is in the direction of the length force of the first and second interdigital electrodes. The direction is perpendicular to .

When a voltage is applied to the two terminals in this state, if the polarity of the voltage is the same as the polarity of the voltage during polarization, an elongation strain will occur in the direction of polarization, and if the polarity of the voltage is opposite to the polarity of the voltage during polarization. In this case, shrinkage distortion occurs in the direction of polarization. When an elongation or contraction strain occurs in the polarization direction, a contraction or expansion strain occurs in the direction perpendicular to the polarization direction, respectively.

As a result of the above, torsional displacement occurs in the piezoelectric ceramic cylinder. Similar torsional displacement occurs in this piezoelectric ceramic cylinder having a hollow portion.

By aligning one end of such a piezoelectric torsional vibrator and a conventional piezoelectric vertical vibrator that expands and contracts in the vertical direction, and joining one end of a metal material to the other end, the other end of the metal material undergoes torsional vibration. and longitudinal vibration are combined to form a longitudinal single-torsion composite vibration, that is, one end performs elliptical vibration in a plane along the axis to form a Urangevin-type longitudinal single-torsion composite vibrator. When a rotor is pressed against at least one end of this composite vibrator, the vertical torsional composite vibration of the other end of the pressed metal material is converted into a rogue rotational motion.

[Example] The present invention will be explained in detail below with reference to the drawings.

Embodiment 1 FIG. 1 is a perspective view showing the structure of an ultrasonic motor according to a first embodiment of the present invention, in which the piezoelectric torsional vibrator 1 shown in FIG. 4 and the piezoelectric longitudinal vibration shown in FIG. Further, metal cylinders 5 and 6 are bonded to both sides of these to form a Langevin-type vertical single-torsion oscillator, and one end face of this Langevin-type vertical single-torsion oscillator is injected in the same manner as in the case of Fig. 10. The shaft 7 is fixed at the vibration node of the Langevin type oscillator,
A rotor 9 rotatably supported by a bearing 8 is pressed through a spring 10 and a nut 11 to one end surface of a Langevin type longitudinal single-torsion vibrator.

FIG. 2 is an explanatory diagram of the operating principle of piezoelectric torsional vibration used in the ultrasonic motor according to the first embodiment of the present invention. In FIG. 2(a), a plurality of electrodes 18 and 19 are formed on one surface of the piezoelectric ceramic plate 17 and intersect with each other.
Every other electrode is connected to common electrodes 18' and 19' to form first and second interdigital electrodes. Figure 2 (
In b), the dashed arrows indicate the direction of polarization when polarization is performed using such first and second interdigital electrodes, and FIGS. As shown in Figure (b), the figure shows the state of distortion that occurs when a DC voltage is applied to the polarized piezoelectric ceramic plate 17, and the solid arrows indicate the direction of the electric field.

As can be seen from Figures 2(e) and (d), when the polarity of the voltage is the same as the polarity of the voltage during polarization, stretching distortion occurs in the direction of polarization, and the polarity of the voltage is the same as the polarity of the voltage during polarization. In the opposite case, shrinkage distortion occurs in the direction of polarization.

Figure 3 shows the state of distortion that occurs on the outer peripheral surface of the cylinder 20 when both end faces of the cylinder 20 are twisted as shown by the arrows in the figure, and shows the state of distortion that occurs on the outer peripheral surface of the cylinder 20 at an angle of 45° with respect to the axial direction of the cylinder 20. Stretching and contraction occurs in the direction of the torsional broken line arrow, and shrinkage distortion occurs in the direction of the dashed-dotted line perpendicular to this direction.

Therefore, first and second interdigital electrodes as shown in Fig. 2 are placed on the outer peripheral surface of the piezoelectric ceramic cylinder so that the direction of the interdigital fingers is at an angle of 45° with respect to the longitudinal direction of the piezoelectric ceramic cylinder. When the polarization process is performed using the first and second interdigital electrodes, and a DC voltage is applied to the same interdigital electrodes, the piezoelectric ceramic cylinder will It is twisted in one direction, and when the polarity of the voltage is opposite to the polarity of the voltage during polarization, it is twisted in the opposite direction.

Furthermore, when the piezoelectric ceramic is cylindrical, similar torsional vibrations occur.

FIG. 4 is a perspective view showing the structure of an embodiment of the piezoelectric torsional vibrator used in the ultrasonic motor according to the first embodiment of the present invention, and shows the outer periphery of approximately half of the ring-shaped piezoelectric ceramic 20'. A plurality of first and second oblique electrodes 22 intersect with each other so as to form an angle of 45'' with respect to the longitudinal direction.
and 23 are formed and connected to the first and second common electrodes 22' and 23', respectively. In FIG. 4, a ring-shaped piezoelectric ceramic 2 ' resonates as if both ends are twisted.

Embodiment 2 FIG. 5 is a perspective view of a structural example of an ultrasonic motor according to a second embodiment of the present invention. and axis 2
A locou 9.9' rotatably supported by bearings 8 and 8' at both ends of the oscillator 6 is pressed against the end of the Langevin type longitudinal single-torsion vibrator by nuts 11 and 11' via springs 10 and 10'. It is composed of

FIG. 6 is a perspective view showing the structure of a vibrator-shaped Langevin type piezoelectric longitudinal-torsion composite vibrator 2 used in an ultrasonic motor according to a second embodiment of the present invention.

The piezoelectric torsional vibrator 1 shown in FIG. 4 and the conventional piezoelectric longitudinal vibrator 103 shown in FIG. It is constructed by joining materials. As shown in the figure, the piezoelectric torsional vibrator 1 is located at a position where the center of the torsional vibrator portion is approximately 1/4 of the total length g of the Langevin type vibrator 2. In this case, the vibration state of the Langevin type vibrator 2 is as shown in FIG. In other words, with respect to torsional vibration, since the center of the torsional oscillator is located at approximately 1/4 of the total length g of the Langevin type oscillator, It resonates in a vibration mode where the position of is the node of vibration. As can be seen from FIG. 7, both ends of the Langevin type vibrator 2 are twisted in the same direction around the central axis of the vibrator. Regarding longitudinal vibration, if the frequency of the applied voltage is the same as the torsional resonance frequency, both ends of the Langevin type vibrator 2 will undergo stretching vibration in the direction of the central axis of this vibrator in synchronization with the torsional resonance. do. Therefore, the extensional vibration reaches its maximum at the timing when the amplitude of the torsional vibration increases.If the phases of the two applied voltages are adjusted in step 5, both sides of the Langevin type vertical torsional oscillator become elliptical along the central axis. Vibrate. In this case, if the phase of one of the applied voltages is changed by 180'', the direction of the elliptical vibration is reversed.

FIG. 8 is a perspective view showing another structural example of a vibrator-like Langevin type piezoelectric vertical single-torsion composite vibrator used in the ultrasonic motor according to the second embodiment of the present invention, Torsional vibrator 1 and piezoelectric longitudinal vibrator 103 shown in FIG.
A pipe-shaped bolt 28 with a threaded end on the outer periphery is passed through the hollow part, and metal pipes 5 and 6- with threaded inner periphery threaded to engage with the bolt are tightened on both sides of the pipe-shaped bolt 28. It is configured. Also in FIG. 8, when the torsional oscillator is placed at a position approximately 1/4 of the total length g of the Langevin type oscillator 3, it vibrates on the same principle as the Langevin oscillator shown in FIG.

As described above, in the ultrasonic motor shown in FIG. 5, the end faces of the Langevin-type vertical single-torsion composite vibrator are twisted in the same direction, so the two rotors 9 and 9' rotate in the same direction.

In addition, the Langevin-type longitudinal single-torsion compound vibrator can be supported and fixed at a 1/4 position from both ends, which is the position of the resonance node of torsional vibration, with ring-shaped support frames 27 and 27', providing stable support. It becomes possible.

[Effects of the Invention] As shown above, according to the present invention, piezoelectric ceramics can be easily manufactured by press molding technology that is generally applied as piezoelectric longitudinal vibrators and torsional vibrators for ultrasonic motors. By using cylinders and printing electrodes on their outer peripheral surfaces, which is also a common technique, piezoelectric torsional oscillators and piezoelectric longitudinal oscillators can be obtained as a single piece, making manufacturing easy and eliminating the need for bonding processes and complex An ultrasonic motor with less variation in characteristics due to processing steps can be obtained.

Furthermore, a similar ultrasonic motor can be obtained by using a piezoelectric ceramic cylinder instead of the piezoelectric ceramic cylinder.

Furthermore, according to the present invention, an ultrasonic motor can be realized in which a shaft passes through the hollow part of a vibrator-shaped piezoelectric longitudinal single-torsion composite vibrator and rotates two rotors simultaneously, and can also drive objects wider than the space between the rotors. be able to. As described above, since the ultrasonic motor of the present invention uses this piezoelectric longitudinal-torsional composite vibrator, an ultrasonic motor with a simple structure and less variation in characteristics can be obtained, and has great practical effects.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the structure of an ultrasonic motor according to the first embodiment of the present invention, and FIG. 2 is an explanatory diagram of the state of distortion when polarization and voltage application are performed using interdigital electrodes. , 3rd
FIG. 4 is a perspective view showing a piezoelectric torsional compound vibrator of an ultrasonic motor according to the first embodiment of the present invention; FIG. The figure is a perspective view showing the structure of an ultrasonic motor according to a second embodiment of the present invention,
FIG. 6 is a perspective view showing the structure of a vibrator-shaped Langevin compound vibrator used in an ultrasonic motor according to a second embodiment of the present invention, and FIG. 7 is a perspective view showing the displacement of the pipe-shaped Langevin compound vibrator of FIG. FIG. 8 is an explanatory diagram showing the size, and FIG. 8 is a perspective view showing another structural example of the pipe-shaped Langevin type piezoelectric vertical single-torsion composite vibrator used in the ultrasonic motor according to the second embodiment of the present invention. The figure is a perspective view showing the structure of a conventional longitudinal single-twist Lilangevin type vibrator, FIG. 10 is a perspective view showing the structure of a conventional vertical single-twist ultrasonic motor, and FIG. A perspective view showing the structure, Figures 12 and 13 are illustrations of the manufacturing process of a conventional torsional oscillator, Figure 14 is an illustration of the manufacturing process of a conventional torsion oscillator, and Figure 15 is an illustration of the manufacturing process of a conventional torsional oscillator. A perspective view showing the structure of a vibrator. FIG. 16 is a perspective view showing another structure of a conventional vertical vibrator. In the figure, 1: piezoelectric vertical single-torsion composite vibrator, 2: piezoelectric torsional vibrator, 3: piezoelectric longitudinal vibrator, 4, 5.5'5", 6.6'
．． 6”: Metal cylinder, 7: Shaft, 8: Bearing, 9: Rotor
10 = Spring, 11: Nut, 17: Piezoelectric ceramic thin plate, 18, 19: Interdigital electrode, 18', 19'
: common electrode, 20: cylindrical elastic body, 20': ring-shaped piezoelectric ceramic, 22.23: interdigital electrode for torsional vibrator, 22'23': common electrode, 24.25: interdigital electrode for longitudinal vibrator , 26: shaft, 27.27': support frame, 28: pipe-shaped bolt, 101: piezoelectric vertical single-torsion composite vibrator, 102: piezoelectric torsional vibrator, 103: piezoelectric longitudinal vibrator, 112: fan-shaped piezoelectric ceramic plate , 113, 114
: Piezoelectric ceramic plate, 115: Piezoelectric ceramic plate prism, 116: Piezoelectric ceramic Fig. 2 Fig. 3 Fig. 4 Fig. 8 Fig. 9 Fig. 11 Fig. 12 Fig. 13 Fig. 10

Claims (1)

[Scope of Claims] A piezoelectric torsional vibrator having a first cross-sectional shape perpendicular to a central axis and torsionally vibrates around the central axis, and a piezoelectric torsional vibrator arranged with one end facing one end of the torsional vibrator. , a piezoelectric longitudinal vibrator having a second cross-sectional shape substantially equal to the first cross-sectional shape and performing stretching vibration in the direction of the central axis, one end of which is joined to the other end of the piezoelectric torsional vibrator; a first metal material having a third cross-sectional shape substantially equal to the first cross-sectional shape; and a fourth metal material having one end joined to the other end of the piezoelectric longitudinal vibrator and having a third cross-sectional shape substantially equal to the first cross-sectional shape. a Lanchevin type vertical-torsion composite vibrator having a second metal material having a cross-sectional shape; and a rotor press-welded to the other end of at least one of the first and second metal materials; The piezoelectric torsional vibrator includes a piezoelectric ceramic having an outer circumferential surface, and a plurality of first diagonal electrodes and a plurality of second diagonal electrodes arranged alternately on the outer circumferential surface in a direction crossing the central axis of the piezoelectric ceramic. An ultrasonic motor characterized by having oblique electrodes.