EP0147112A2
Expired / Lapsed
EP
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Piezoelectric actuator using bimorph element
Assignee: NTT Inc
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Filing: 1984-12-06
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Granted: —
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Expires: 2004-12-06
Abstract
Abstract A piezoelectric actuator using a bimorph element, comprises: a bimorph element having at least one pair of piezo elements respectively on two surfaces of a central electrode and an electrode formed on a surface of each piezo element which is opposite to a surface contacting the central electrode, the piezo elements formed on the two surfaces of the central electrode being polarized in the same direction with respect to a direction of thickness of the bimorph element; a drive input circuit arranged such that a cathode of a first directional voltage limiting circuit is connected to one electrode contacting a positively polarized surface of the piezo element whose negatively polarized surface contacts the central electrode, that an anode of a second directional voltage limiting circuit is connected to the other electrode contacting a negatively polarized surface of the piezo element whose positively polarized surface contacts the central electrode, that an anode of the first directional voltage limiting circuit and a cathode of the second directional voltage limiting circuit are commonly connected to constitute one drive input terminal, and that the central electrode serves as the other drive input terminal; a constant voltage source for applying a constant voltage to the drive input circuit; and a polarity switching circuit, arranged between the constant voltage source and the drive input circuit, for switching a polarity of the constant voltage source with respect to the one and the other drive input terminals of the drive input circuit.
Inventors
- 👤 Tomono Akira
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 06:25
CPC Classifications
H; H10; H10N; H10N30/00; H10N30/80; H10N30/802; H10N30/20; H10N30/204; H10N30/2041; H10N30/2042; H10N30/87
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
242 words
A piezoelectric actuator using a bimorph element, comprising: a bimorph element having at least one pair of piezo elements respectively on two surfaces of a central electrode and an electrode formed on a surface of each piezo element which is opposite to a surface contacting said central electrode, said piezo elements formed on the two surfaces of said central electrode being polarized in the same direction with respect to a direction of thickness of said bimorph element; a drive input circuit arranged such that a cathode of a first directional voltage limiting circuit is connected to one electrode contacting a positively polarized surface of the piezo element whose negatively polarized surface contacts said central electrode, that.an anode of a second directional voltage limiting circuit is connected to the other electrode contacting a negatively polarized surface of the piezo element whose positively polarized surface contacts said central electrode, that an anode of said first directional voltage limiting circuit and a cathode of said second directional voltage limiting circuit are commonly connected to constitute one drive input terminal, and that said central electrode serves as the other drive input.terminal; a constant voltage source for applying a constant voltage to said drive input circuit; and a polarity switching circuit, arranged between said constant voltage source and said drive input circuit, for switching a polarity of said constant voltage source with respect to said one and the other drive input terminals of said drive input circuit.
Claim 2
Dependent Claim
242 words
A piezoelectric actuator using a bimorph element, comprising: a bimorph element having at least one pair of piezo elements respectively on two surfaces of a central electrode and an electrode formed on a surface of each piezo element which is opposite to a surface contacting said central electrode, said piezo elements formed on the two surfaces of said central electrode being polarized in the same direction with respect to a direction of thickness of said bimorph element; a drive input circuit arranged such that a cathode of a first directional voltage limiting circuit is connected to one electrode contacting a positively polarized surface of the piezo element whose negatively polarized surface contacts said central electrode, that.an anode of a second directional voltage limiting circuit is connected to the other electrode contacting a negatively polarized surface of the piezo element whose positively polarized surface contacts said central electrode, that an anode of said first directional voltage limiting circuit and a cathode of said second directional voltage limiting circuit are commonly connected to constitute one drive input terminal, and that said central electrode serves as the other drive input.terminal; a constant voltage source for applying a constant voltage to said drive input circuit; and a polarity switching circuit, arranged between said constant voltage source and said drive input circuit, for switching a polarity of said constant voltage source with respect to said one and the other drive input terminals of said drive input circuit.
Claim 3
Dependent Claim
104 words
An actuator according to claim 1, wherein a plurality of piezo elements are formed on two surfaces of said central electrode, the number of piezo elements formed on one surface of said central electrode being the same as that on the other surface thereof, and the piezo elements formed on each surface of said central electrode being polarized in the same direction and being arranged such that every two adjacent piezo elements have opposing polarization directions, and electrodes of said plurality of piezo elements which are not connected to said directional voltage limiting circuits being commonly connected to constitute the other drive input terminal.
Claim 4
Dependent Claim
29 words
An actuator according to claim 1, wherein one end of said bimorph element is fixed, and an actuator mechanism is connected to a free end of said bimorph element.
Claim 5
Dependent Claim
16 words
An actuator according to claim 1, wherein said directional voltage limiting circuits comprise Zener diodes, respectively.
Claim 6
Dependent Claim
115 words
An actuator according to claim 1, wherein a power source voltage V c is set to be higher than the polarization degradation voltage Vd of the piezo element, the power source voltage V c or a voltage close to the power source voltage V C is applied to one piezo element in the same direction as the polarization direction through said central electrode, and a voltage is applied to the other piezo element to cause a depolarization effect in a direction opposite to the.polarization direction, the depolarization effect being cancelled by the polarization effect caused by the power source voltage V or the voltage close to the power source voltage V c upon polarity inversion.
Claim 7
Dependent Claim
41 words
An actuator according to claim 1, wherein the voltage applied in the direction opposite to the polarization direction comprises a voltage obtained by subtracting at least 1/10 of the polarization breakdown voltage Vp from the power source voltage V C .
Claim 8
Dependent Claim
59 words
An actuator according to claim 1, wherein said directional voltage limiting circuits comprise PNPN element circuits each of which is turned on at a predetermined voltage, the anodes of said directional voltage limiting circuits corresponding to cathodes of said PNPN element circuits, and the cathodes of said directional voltage limiting circuits corresponding to anodes of said PNPN element circuits.
Claim 9
Dependent Claim
22 words
An actuator according to claim 6, wherein each of said PNPN elements is turned on by a voltage applied upon polarity inversion.
Claim 10
Dependent Claim
84 words
An actuator according to claim 1, wherein said constant voltage source comprises a circuit for boosting a power source voltage E to the constant voltage V C , and said polarity switching circuit receives a ground level and the constant voltage V c and controls switching elements at the power source voltage or a voltage lower than the constant voltage V c so as to switch a polarity of the constant voltage V and to apply the constant voltage to said drive input circuit.
Claim 11
Dependent Claim
54 words
An actuator according to claim 1, wherein said polarity switching circuit comprises a switching circuit obtained by bridging four transistors including two Darlington transistor pairs, one of two transistor pairs of said four transistors connected in parallel with each other or connected diagonally being held in an ON state.in response to a control signal.
Claim 12
Dependent Claim
57 words
An actuator according to claim 1, wherein said polarity switching circuit comprises a switching circuit constituted by four bridge-connected thyristors operated in response to a pulse, one of two thyristor pairs of said four bridge-connected thyristors connected in parallel with each other or connected diagonally being held in an ON state in response to a control signal.
Claim 13
Dependent Claim
23 words
An actuator according to claim 1, wherein said constant current circuit is arranged between said constant voltage source and said drive input circuit.
Claim 14
Dependent Claim
14 words
An actuator according to claim 3,.wherein said actuator mechanism comprises a pivot arm mechanism.
Claim 15
Dependent Claim
22 words
An actuator according to claim 3, further comprising a stopper for regulating swinging movement of said actuator mechanism within an allowable range.
Claim 16
Dependent Claim
48 words
An actuator according to claim 3, wherein a magnet mechanism comprises magnetic members which are respectively disposed in a vicinity of an operating end of said actuator mechanism and at a fixed portion in a vicinity of a displacement near-end position thereof, said magnetic members attracting each other.
Claim 17
Dependent Claim
23 words
An actuator according to claim 3, wherein said actuator mechanism controls a coin rolling along a coin guide of a coin processing apparatus.
Claim 18
Dependent Claim
22 words
An actuator according to claim 1, further comprising a stopper for regulating swinging movement of said bimorph element within an allowable range.
Claim 19
Dependent Claim
50 words
An actuator according to claim 1, wherein said central electrode comprises a magnetic material, and a magnet is arranged in a vicinity of a displacement near-end position of the free end of said bimorph element, said magnet being attracted to the free end when the free end comes closer thereto.
Claim 20
Dependent Claim
19 words
An actuator according to claim 1, wherein a surface of said bimorph element is coated with an insulating resin.
Claim 21
Dependent Claim
22 words
An actuator according to claim 19, wherein the insulating resin comprises a soft resin material and a hard resin material coated thereon.
Claim 22
Dependent Claim
29 words
An actuator according to claim 1, wherein said polarity switching circuit performs switching after said bimorph element is displaced in a predetermined direction and a predetermined operation is performed.
References Cited (Backward Citations)
No citation records indexed.
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