Ultrasonic motor and method of fabricating
First Claim
1. An ultrasonic motor comprising an annular piezoelectric device, a transducer arranged on the piezoelectric device, a rotary member in pressure contact with the transducer, and means for applying two different types of high frequency AC voltages about 90 degrees apart in phase from each other to the piezoelectric device thereby to generate a traveling wave in the transducer and thus to frictionally drive the rotary member,wherein the product of the piezoelectric constant d31 constituting the piezoelectric characteristic obtained by the resonance-antiresonance method for a drive source including the piezoelectric device and the transducer in close contact with each other, the admittance Ym and the mechanical quality factor Qm, i.e. d31×
- Ym×
Qm≧
63×
10−
10 m·
S/V.
1 Assignment
0 Petitions
Accused Products
Abstract
An ultrasonic motor capable of producing a high output and a method of fabricating the same are disclosed. The ultrasonic motor has a drive source 100 including a piezoelectric device 1 and a transducer 21, in close contact with each other, in which the product of the piezoelectric constant d31, the admittance Ym and the mechanical quality factor Qm measured under the conditions of the drive source 100 is not less than 63×1031 10 m·S/V.
8 Citations
6 Claims
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1. An ultrasonic motor comprising an annular piezoelectric device, a transducer arranged on the piezoelectric device, a rotary member in pressure contact with the transducer, and means for applying two different types of high frequency AC voltages about 90 degrees apart in phase from each other to the piezoelectric device thereby to generate a traveling wave in the transducer and thus to frictionally drive the rotary member,
wherein the product of the piezoelectric constant d31 constituting the piezoelectric characteristic obtained by the resonance-antiresonance method for a drive source including the piezoelectric device and the transducer in close contact with each other, the admittance Ym and the mechanical quality factor Qm, i.e. d31× - Ym×
Qm≧
63×
10−
10 m·
S/V. - View Dependent Claims (2, 3)
- Ym×
-
4. An ultrasonic motor comprising an annular piezoelectric device, a transducer arranged on the piezoelectric device, a rotary member in pressure contact with the transducer, and means for applying two types of high frequency AC voltages about 90 degrees apart in phase from each other to the piezoelectric device thereby to generate a traveling wave in the transducer and thus to frictionally drive the rotary member,
wherein the composition of the piezoelectric device is given by a general formula
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5. A method of fabricating an ultrasonic motor comprising an annular piezoelectric device, a transducer arranged on the piezoelectric device, a rotary member in pressure contact with the transducer, and means for applying two types of high frequency AC voltages about 90 degrees apart in phase from each other to the piezoelectric device thereby to generate a traveling wave in the transducer and thus to frictionally drive the rotary member, comprising the steps of:
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measuring the resonance-antiresonance characteristic of the impedance by applying the sine wave of ±
1 V to a drive source including the piezoelectric device and the transducer in close contact with each other in the frequency range containing the resonance-antiresonance frequency of the motor in one of the two phases of the applied high-frequency AC voltage,measuring the piezoelectric constant d31, the admittance Ym and the mechanical quality factor Qm obtained from he resonance-antiresonance characteristic, and selecting the drive source in such a manner that the product of the piezoelectric constant d31, the admittance Ym and the mechanical quality factor Qm is given as d31×
Ym×
Qm≧
63×
10−
10 m·
S/V.- View Dependent Claims (6)
-
Specification