EP0258449A1
Expired / Lapsed
EP
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Ultrasonic motor
Assignee: Panasonic Holdings Corp
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Filing: 1987-02-17
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Granted: —
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Expires: 2007-02-17
Abstract
Abstract An ultrasonic motor in which elastic progressive waves are excited in a vibration member (4) which consists of a piezo-electric substance (1) and an elastic substance (2) and in which a rotary member placed on the vibration member (4) in contact therewith under the application of a pressure is driven by the frictional force. The vibration member (4) has a disc-like shape, and electrode groups (9, 10) provided for the piezo-electric substance (1) are arranged concentrically maintaining phases that are different in the circumferential direction in which the vibration proceeds. The electrode groups (9, 10) excite the vibration member (4) in a quadratic or higher flexural vibration mode in the radial direction and in a cubic or higher flexural vibration mode in the circumferential direction so as to produce an equal mechanical impedance as viewed from the electrode groups (9,10). Standing waves of flexural vibrations excited by the electrode groups (9, 10) are superposed, so that the flexural vibration proceeds in the circumferential direction to drive the motor.
Inventors
- 👤 Osamu 12-1 Matsuigaoka 3-Chome Kawasaki
- 👤 Ritsuo 19-7 Uzumasa Higashigaoka Inaba
- 👤 Akira 97-6 Daigo Ooji-Cho Tokushima
- 👤 Katsu 11-3 Ooimazato Nishi 2-Chome Takeda
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 02:24
CPC Classifications
H; H02; H02N; H02N2/00; H02N2/10; H02N2/16; H02N2/166
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
155 words
An ultrasonic motor wherein elastic travelling wave is excited in a vibrating stator comprising a piezoelectric element and an elastic element, to drives a rotor which is disposed to touch said vibrating stator with pressure by friction forces, characterized by being constituted that said vibrating element is substantially disk-shaped, and electrodes which are attached to said piezoelectric element are disposed in a form of two sets of concentric circles having each other different phases in position in a circumferential direction which is a travelling direction of vibration of said vibrating stator, to excite said vibrating stator in flexural vibration modes of second order or higher in radial direction and of third order or higher in circumferential direction, and that at least mechanical impedances seen from each electrode are equal, to make said flexural vibration travel in said circumferential direction by superimposition of standing waves of said flexural viration excited by the sets of said electrodes.
Claim 2
Dependent Claim
155 words
An ultrasonic motor wherein elastic travelling wave is excited in a vibrating stator comprising a piezoelectric element and an elastic element, to drives a rotor which is disposed to touch said vibrating stator with pressure by friction forces, characterized by being constituted that said vibrating element is substantially disk-shaped, and electrodes which are attached to said piezoelectric element are disposed in a form of two sets of concentric circles having each other different phases in position in a circumferential direction which is a travelling direction of vibration of said vibrating stator, to excite said vibrating stator in flexural vibration modes of second order or higher in radial direction and of third order or higher in circumferential direction, and that at least mechanical impedances seen from each electrode are equal, to make said flexural vibration travel in said circumferential direction by superimposition of standing waves of said flexural viration excited by the sets of said electrodes.
Claim 3
Dependent Claim
40 words
An ultrasonic motor in accordance with claim 1, characterized in that electrodes which are constituted in a form of two sets of said concentric circles are provided circle of said flexural vibration, as a driving electrode of said piezoelectric element.
Claim 4
Dependent Claim
37 words
An ultrasonic motor in accordance with claim 1, characterized in that each one set of driving electrode is provided concentrically inside and outside a nodal circle of said flexural vibration, as driving electrodes of said piezoelectric element.
Claim 5
Dependent Claim
79 words
An ultrasonic motor in accordance with claim 1, characterized in that two sets of a driving electrodes are provided inside a nodal circle and one set of driving electrode are provided outside said nodal circle of said flexural vibration in concentrical manner, as driving electrodes of said piezoelectric element, and a driving electrode outside an external nodal circle is combined with any of driving electrodes inside said nodal circle in use, to make another two sets of driving electrodes.
Claim 6
Dependent Claim
38 words
An ultrasonic motor in accordance with claim 1, characterized in that said vibrating eJement is fixed in position via a nodal circle part of.a travelling wave of said flexural vibration, or an internal circumference of said vibrating stator.
Claim 7
Dependent Claim
43 words
An ultrasonic motor in accordance with claim 1, characterized in that projections are provided so that tips thereof are made to contact with a loop of said vibration of said flexural vibration of a contacting surface with a rotor of said vibrating stator.
Claim 8
Dependent Claim
56 words
An ultrasonic motor in accordance with claim 6, characterized in that number of said projections is a multiple by an integer of four per one wavelength of said travelling wave, and said projections are disposed so that said projections are not on a position of said loops of two standing waves which constitute said travelling wave.
Claim 9
Dependent Claim
29 words
An ultrasonic motor in accordance with claim 6, characterized in that a lowest resonance frequency is higher than a resonance frequency of said flexural vibration of said vibrating stator.
References Cited (Backward Citations)
No citation records indexed.
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