Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
2006-11-28
2006-11-28
Budd, Mark (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S311000, C310S358000
Reexamination Certificate
active
07141911
ABSTRACT:
In a disclosed method, a piezoelectric element1has an asymmetrical hysteresis characteristic of polarization-electric field different in absolute values between a coercive field of positive electric side and a coercive field of negative electric field side, and is polarized in the film thickness direction of the piezoelectric element1and in a direction of smaller absolute value of the coercive field, and as a position control voltage Q1for position control by ditorting the piezoelectric element1in a direction orthogonal to the film thickness direction of the piezoelectric element1,a voltage equivalent to an electric field of 0.4 or less of the coercive field value is applied in the film thickness direction of the piezoelectric element1in a direction of larger absolute value of the coercive field. Further, a position control voltage Q2for recovering from deterioration of polarization of the piezoelectric element1is applied by superposing on the position control voltage Q1, or changing over with the position control voltage Q1, or while the position control voltage Q1is not applied, and therefore recovering from deterioration of polarization characteristic, the displacement characteristic is stabilized for a long period of time.
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Kita Hiroyuki
Kuwajima Hideki
Matsushita Electric - Industrial Co., Ltd.
McDermott Will & Emery LLP
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