PURPOSE: To prevent the occurrence of the malfunction due to a disturbance impact by adding an impact detecting sensor with a temporal signal processing mechanism or a mechanism for processing the sum or difference of or between two or more kinds of signals.

CONSTITUTION: Signals from a vibration pickup element mark composed of piezoelectric ceramic are amplified and selected in a filter mechanism with a amplifier. A detective processing in applied to the signals selected by a selecting mechanism D and detected signals thus obtained are converted to transmitter signals by a transmitter signal converting mechanism S. By providing above-described circuit structure with a temporal signal processing mechanism T, the rupture of glass due to an impact by a hammer or the like produces an instantaneous rupture signal and the rupture of glass in grinding and cutting produces signals for a long time period. The occurrence of a malfunction is prevented by utilizing the above-described temporal phenomena.