Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
2008-04-08
2008-04-08
San Martin, J. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S314000, C310S317000, C310S319000
Reexamination Certificate
active
07355321
ABSTRACT:
A mechanical quantity sensor includes a current-to-voltage converter/signal adder circuit that converts electric current signals flowing through two piezoelectric vibrators into voltage signals. The piezoelectric vibrators receive stresses generated by a mechanical quantity, such as acceleration, in opposite directions. A voltage amplifier/amplitude limiter circuit amplifies an added signal obtained from the two voltage signals and limits its amplitude. A phase-difference-to-voltage converter circuit detects a difference in the phases of the added signal and a feedback voltage signal applied to an acceleration detection element. A phase shifter circuit controls the phase of the feedback voltage signal so that the phase is a predetermined phase. A filter circuit minimizes frequency components higher than an oscillation frequency in an unwanted frequency band. By increasing the resistance of resistors so as to increase the damping ratio, temperature stability is increased. Accordingly, abnormal oscillation is prevented by the filter circuit, and fluctuation in the characteristics is minimized by the phase control circuit.
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Official communication issued in the counterpart German Application No. 11 2004 000 934.0, mailed on Aug. 8, 2007.
Keating & Bennett LLP
Martin J. San
Murata Manufacturing Co. Ltd.
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