| 摘要 |
PROBLEM TO BE SOLVED: To provide a gas leakage alarm which supplies power to a gas sensor 2, an alarm buzzer 5, and an LED 6 from the same power source, and alternately drives the alarm buzzer 5 and LED 6 when an alarm is issued, and prevents malfunction by obtaining a stable sensor output when the alarm is issued. SOLUTION: An AC voltage stepped down by a transformer 4 is supplied to the gas sensor 2. A sensor output Vs generated between a connection point of a reference element Rr and a sensor element Rs, and a connection point of a resistor R1 and a resistor R2 of the gas sensor 2 is amplified at a differential amplifier A1, and is supplied to a control part 1. The AC voltage of the transformer 4 is rectified by a rectification circuit 8, and is supplied to the alarm buzzer 5 and the LED 6. Lighting of the LED 6 and ringing of the alarm buzzer 5 are repeated at predetermined cycles when an alarm is issued. A sensor output Vs is sampled while the LED 6 is on, to determine transition of an alarm state and whether to stop the alarm. COPYRIGHT: (C)2011,JPO&INPIT |
