EP0261810A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Drive method for ultrasonic motor providing enhanced stability of rotation
Assignee: Panasonic Holdings Corp
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Filing: 1987-08-26
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Granted: —
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Expires: 2007-08-26
Abstract
Abstract A method of driving an ultrasonic motor having a rotation body (6) which is rotated by travelling waves generated in a vibrator body (3), whereby the drive frequency of the motor is controlled in accordance with the value of an operating parameter such as phase difference between drive current and voltage, such as to maintain the drive frequency at a value which is lower than the antiresonance frequency of the vibrator body (3) and higher than a highest resonance frequency of the vibrator body (3) in a hysteresis loop exhibited by a resonance frequency characteristic of the vibrator body (3). Continuous stable operation is attained, irrespective of the effects of temperature and load changes upon the motor operating characteristics.
Inventors
- 👤 Osamu Kawasaki
- 👤 Katsu Takeda
- 👤 Ritsuo Inaba
- 👤 Tetsuji Fukada
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 05:26
CPC Classifications
H; H02; H02P; H02P1/00; H02N; H02N2/00; H02N2/10; H02N2/14; H02N2/142; H02N2/16; H02N2/163
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
106 words
A method of driving an ultrasonic motor comprising a vibration body formed of a piezoelectric body and an elastic body and a rotary body which is disposed in contact with said vibration body, the vibration body being driven to vibrate by an alternating drive voltage which is applied to said piezoelectric body for thereby rotating the rotary body by a frictional force, the method being characterized in detecting a value of a specific operating parameter of said motor, and controlling a drive frequency of said alternating drive voltage based upon results of said detection such as to maintain said parameter within a specific range of values.
Claim 2
Independent Claim
106 words
A method of driving an ultrasonic motor comprising a vibration body formed of a piezoelectric body and an elastic body and a rotary body which is disposed in contact with said vibration body, the vibration body being driven to vibrate by an alternating drive voltage which is applied to said piezoelectric body for thereby rotating the rotary body by a frictional force, the method being characterized in detecting a value of a specific operating parameter of said motor, and controlling a drive frequency of said alternating drive voltage based upon results of said detection such as to maintain said parameter within a specific range of values.
Claim 3
Dependent Claim
62 words
A method of driving an ultrasonic motor according to claim 1, in which said operating parameter is selected from a group of operating parameters which include a phase difference between said alternating drive voltage and a resultant current which flows in said piezoelectric body, a level of a predetermined component of said current, and a speed of rotation of said rotary body.
Claim 4
Dependent Claim
106 words
A method of driving an ultrasonic motor according to claim 1, in which said vibration body exhibits non-linearity of operation, resulting in a hysteresis loop being formed in a relationship between said drive frequency and values of resonance frequency of said vibration body, and in which said specific range of values of said operating parameter corresponds to a frequency range of said drive frequency that extends from a value of said drive frequency which is higher than a highest value of said resonance frequency in said hysteresis loop to a value of said drive frequency which is lower than an antiresonance frequency of said vibration body.
Claim 5
Dependent Claim
58 words
A method of driving an ultrasonic motor according to claim 3, in which said frequency control is executed by determining a set value for said operating parameter which is within said specific range of values, and controlling said drive frequency such as to minimize a difference between said set value and an actual value of said operating parameter.
Claim 6
Dependent Claim
65 words
A method of driving an ultrasonic motor according to claim 3, in which said frequency control is executed by sweeping said drive frequency within a predetermined frequency sweep range which includes said frequency range corresponding to said range of operating parameter values, and halting said frequency sweeping when said operating parameter is detected to have reached a specific value within said range of values thereof.
Claim 7
Dependent Claim
44 words
A method of driving an ultrasonic motor according to claim 5, in which said operating parameter is said phase difference between drive voltage and current, and in which said frequency sweeping is executed downward from a high end of said range of frequency variation.
Claim 8
Dependent Claim
94 words
A method of driving an ultrasonic motor according to claim 3, in which said frequency control is executed by sweeping said drive frequency within a range of frequency variation which includes said frequency range corresponding to said predetermined range of values of the operating parameter, halting said frequency sweeping when said operating parameter is detected to have reached a predetermined limit value of said range of values, and fixing said drive frequency at a value which differs by a predetermined amount from the value thereof at the point of halting of said frequency sweeping.
Claim 9
Dependent Claim
79 words
A method of driving an ultrasonic motor according to claim 7, in which said frequency sweeping is executed upward from a low end of said range of frequency variation, and in which said limit value substantially corresponds to a resonance frequency of said vibrator body, in which said operating parameter is said phase difference between drive voltage and current, said resonance frequency being detected as a minimum value of said phase difference which is attained during said frequency sweeping.
Claim 10
Independent Claim
51 words
A method of driving an ultrasonic motor according to claims 5 or 7, and further comprising detecting a condition, following termination of said drive frequency sweeping, in which said operating parameter has deviated outside said predetermined range of values, and restarting said drive frequency sweeping operation when said condition is detected.
Claim 11
Independent Claim
134 words
A method of driving an ultrasonic motor comprising a vibration body formed of a piezoelectric body and an elastic body and a rotary body which is disposed in contact with the vibration body, the vibration body being driven to vibrate by an alternating drive voltage which is applied to said piezoelectric body for thereby rotating the rotary body by a frictional force, said vibration body exhibiting non-linearity of operation whereby a hysteresis loop is formed in a relationship between said drive frequency and values of resonance frequency of said vibration body, the method being characterized in controlling the drive frequency of said alternating drive voltage to an arbitrary value which is higher than a highest value of resonance frequency of said hysteresis loop and is lower than an antiresonance frequency of said vibration body.
Claim 12
Independent Claim
134 words
A method of driving an ultrasonic motor comprising a vibration body formed of a piezoelectric body and an elastic body and a rotary body which is disposed in contact with the vibration body, the vibration body being driven to vibrate by an alternating drive voltage which is applied to said piezoelectric body for thereby rotating the rotary body by a frictional force, said vibration body exhibiting non-linearity of operation whereby a hysteresis loop is formed in a relationship between said drive frequency and values of resonance frequency of said vibration body, the method being characterized in controlling the drive frequency of said alternating drive voltage to an arbitrary value which is higher than a highest value of resonance frequency of said hysteresis loop and is lower than an antiresonance frequency of said vibration body.
Claim 13
Independent Claim
240 words
A method of driving an ultrasonic motor comprising a vibration body formed of a piezoelectric body and an elastic body and a rotary body which is disposed in contact with said vibration body, the vibration body being driven to vibrate by an alternating drive voltage which is applied to said piezoelectric body for thereby rotating the rotary body by a frictional force, the method comprising successive steps of: (a) sweeping a drive frequency of said vibration body downward from a high end of a predetermined frequency sweep range, said sweep range including at least a frequency range extending between an antiresonance frequency of said vibration body and a highest resonance frequency of said vibration body with respect to a hysteresis loop exhibited by a resonance frequency characteristic of said vibration body; (b) detecting when a predetermined operating parameter of said vibration body reaches a specific value thereof which corresponds to a value of said drive frequency that is higher than said highest resonance frequency and lower than said antiresonance frequency (c) when said specific value is detected, halting said frequency sweeping to thereby fix the value of said drive frequency; (d) monitoring said operating parameter to detect whether the value thereof, subsequently deviates from said predetermined value by more than a predetermined permissible range of variation and; (e) if deviation of said operating parameter value outside said permissible range of variation is detected, successively repeating said steps (a) through (d).
Claim 14
Independent Claim
240 words
A method of driving an ultrasonic motor comprising a vibration body formed of a piezoelectric body and an elastic body and a rotary body which is disposed in contact with said vibration body, the vibration body being driven to vibrate by an alternating drive voltage which is applied to said piezoelectric body for thereby rotating the rotary body by a frictional force, the method comprising successive steps of: (a) sweeping a drive frequency of said vibration body downward from a high end of a predetermined frequency sweep range, said sweep range including at least a frequency range extending between an antiresonance frequency of said vibration body and a highest resonance frequency of said vibration body with respect to a hysteresis loop exhibited by a resonance frequency characteristic of said vibration body; (b) detecting when a predetermined operating parameter of said vibration body reaches a specific value thereof which corresponds to a value of said drive frequency that is higher than said highest resonance frequency and lower than said antiresonance frequency (c) when said specific value is detected, halting said frequency sweeping to thereby fix the value of said drive frequency; (d) monitoring said operating parameter to detect whether the value thereof, subsequently deviates from said predetermined value by more than a predetermined permissible range of variation and; (e) if deviation of said operating parameter value outside said permissible range of variation is detected, successively repeating said steps (a) through (d).
Claim 15
Independent Claim
272 words
A method of driving an ultrasonic motor comprising a vibration body formed of a piezoelectric body and an elastic body and a rotary body which is disposed in contact with said vibration body, the vibration body being driven to vibrate by an alternating drive voltage which is applied to said piezoelectric body for thereby rotating the rotary body by a frictional force, the method comprising successive steps of: (a) sweeping a drive frequency of said vibration body upward from a high end of a predetermined frequency sweep range, said sweep range including at least a frequency range extending between an antiresonance frequency of said vibration body and a highest resonance frequency of said vibration body with respect to a hysteresis loop exhibited by a resonance frequency characteristic of said vibration body; (b) detecting when a predetermined operating parameter of said vibration body reaches a specific value thereof which corresponds to said resonance frequency; (c) when said specific value is detected, halting said frequency sweeping and fixing of said drive frequency at a value which is equal to the drive frequency value at the point of halting said frequency sweeping, incremented by a predetermined amount, said amount being determined such as to set said drive frequency to a value which is higher than said highest resonance frequency and lower than said antiresonance frequency; (d) monitoring said operating parameter to detect whether the value thereof subsequently deviates from said predetermined value by more than a predetermined permissible range of variation and; (e) if deviation of said operating parameter value outside said permissible range of variation is detected, successively repeating said steps (a) through (d).
Claim 16
Independent Claim
272 words
A method of driving an ultrasonic motor comprising a vibration body formed of a piezoelectric body and an elastic body and a rotary body which is disposed in contact with said vibration body, the vibration body being driven to vibrate by an alternating drive voltage which is applied to said piezoelectric body for thereby rotating the rotary body by a frictional force, the method comprising successive steps of: (a) sweeping a drive frequency of said vibration body upward from a high end of a predetermined frequency sweep range, said sweep range including at least a frequency range extending between an antiresonance frequency of said vibration body and a highest resonance frequency of said vibration body with respect to a hysteresis loop exhibited by a resonance frequency characteristic of said vibration body; (b) detecting when a predetermined operating parameter of said vibration body reaches a specific value thereof which corresponds to said resonance frequency; (c) when said specific value is detected, halting said frequency sweeping and fixing of said drive frequency at a value which is equal to the drive frequency value at the point of halting said frequency sweeping, incremented by a predetermined amount, said amount being determined such as to set said drive frequency to a value which is higher than said highest resonance frequency and lower than said antiresonance frequency; (d) monitoring said operating parameter to detect whether the value thereof subsequently deviates from said predetermined value by more than a predetermined permissible range of variation and; (e) if deviation of said operating parameter value outside said permissible range of variation is detected, successively repeating said steps (a) through (d).
Claim 17
Independent Claim
64 words
A method of driving an ultrasonic motor according to claims 11 or 12, in which said operating parameter is selected from a group of operating parameters which include a phase difference between said alternating drive voltage and a resultant current which flows in said piezoelectric body, a level of a predetermined component of said current, and a speed of rotation of said rotary body.
Claim 18
Dependent Claim
106 words
Apparatus for driving an ultrasonic motor comprising a vibration body formed of a piezoelectric body and an elastic body and a rotary body which is disposed in contact with said vibration body, the vibration body being driven to vibrate by an alternating drive voltage which is applied to said piezoelectric body for thereby rotating the rotary body by a frictional force, characterised by means for detecting a value of a specific operating parameter of said motor, and means for controlling a drive frequency of said alternating drive voltage based upon results of said detection such as to maintain said parameter within a specific range of values.
Claim 19
Dependent Claim
106 words
Apparatus for driving an ultrasonic motor comprising a vibration body formed of a piezoelectric body and an elastic body and a rotary body which is disposed in contact with said vibration body, the vibration body being driven to vibrate by an alternating drive voltage which is applied to said piezoelectric body for thereby rotating the rotary body by a frictional force, characterised by means for detecting a value of a specific operating parameter of said motor, and means for controlling a drive frequency of said alternating drive voltage based upon results of said detection such as to maintain said parameter within a specific range of values.
Claim 20
Dependent Claim
9 words
An ultrasonic motor including apparatus according to claim 14.
References Cited (Backward Citations)
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