LONGITUDINAL CRACK SENSING DEVICE FOR CONVEYOR BELT

PURPOSE:To prevent missensing and thereby enhance the reliability by installing aux. coupling electrodes adjacent to the coupling electrodes in parallel therewith, transmitting synchronous pulses upon its receiving signal, and by arranging so that the sensing signal is emitted only when synchronous pulse signals are fed. CONSTITUTION:During a conveyor 3 being in operation an electric conductor 4 faces coupling electrodes 5, 6 and aux. coupling electrodes 7, 8 periodically. Electric signals f1, f2 impressed on the coupling electrodes 5, 6 respectively Pf1, Pf2, Sf1, Sf2 are emitted from the electrodes 5-8 each time they face said electric conductor 4 to be fed into main pulse generator circuits 15, 17 and synchronous pulse circuits 16, 18 through amplifier circuits 11-14, respectively, so as to actuate emission of pulse signals P1, P2, S1, S2. If at this time only S1, S2 are fed, sensing signal generators 19, 20 emit longitudinal cracks sensing signals D1, D2. This may prevent missensing to lead to enhancement of reliability.