To provide a pressure sensitive sensor hardly influenced by disturbance with excellent detection performance and manufacturing efficiency.
A piezoelectric sensor 8 deforms with an elastic body 14 and a voltage signal generates from the piezoelectric sensor 8 according to an applied acceleration. The signal is signal-processed at a filter, a magnification and a comparator circuit of a signal processing part 9, and the determination signal is transmitted to a controlling means 10. When a short circuit or a disconnection between a central electrode 8a and an outside electrode 8c of the piezoelectric sensor 8 occurs, the combined impedance of the piezoelectric sensor 8 and a resistance 11 from view of the signal processing part changes, the trouble of the disconnection or the short circuit of the electrodes is detected by detecting this change by the signal processing part 9 thereof. With the constitution of the piezoelectric sensor 8 whereby the both terminal parts of the piezoelectric sensor 8 are folded into a radio wave shielding body 12 covering the signal processing part 9, to perform radio wave shielding constitution individually is not necessary, the constitution is simplified thereof to reduce cost and improve manufacturing efficiency.
ETO MITSUHIRO
Hiroki Naito
Daisuke Nagano
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