| 摘要 |
PURPOSE:To discriminate the time when two input signals take the same code, by subtracting the output from a circuit, which performs output, only when a high potential signal in two input signals is negative, from the output from a circuit which performs output only when the low potential signal in said input signals is positive. CONSTITUTION:A thermal detection type burglar apparatus 1 has thermal detection sensors 2a, 2b and 3a, 3b and differential amplifiers 2c, 3c and connected to a signal circuit 10 and an alarm circuit 9. The signal circuit 10 includes a positive direction diode 5, which performs output only when the low potential signal selected by a selection circuit 4 is positive and a negative direction diode circuit 7 which performs output only when the high potential signal selected by a selection circuit 6 is negative. A differential amplifier 8 subtracts the output of the circuit 7 from that of the circuit 5 to apply output to an alarm circuit 9. When a person invades, the outputs of the differential amplifiers 2a, 3c and the amplifier 8 are shown by (a), (b), (c) of the drawing and the alarm circuit operates but is not operated by a small animal because said animal is detected only by one of the thermal detection sensors. |
