LIGHTING DEVICE FOR EMERGENCY LIGHT

PROBLEM TO BE SOLVED: To make a relay circuit simpler and cheaper by connecting a thyristor, a thermistor, and the like in series with the relay circuit, and causing a lamp to turn on when an earthquake sensor is operating and to turn off automatically after a certain time. SOLUTION: While a vibration sensor 4 is operating, a thyristor 3 carries a current, a current is supplied to a relay coil 7, and a relay contact 8 is closed to turn on a lamp 5. With the lamp turned on, the thyristor 3 is short-circuited via the contact 8 and a thermistor(Th)9 and restored to an open state, but the coil 7 is kept operating by a current flowing therethrough via the Th9. The Th9, having a positive temperature coefficient, is increased in internal resistance with rise of temperature, and is heated to high temperatures while the lamp 5 is on, so that the coil 7 is decreased in current and starts opening action. Therefore the lamp 5 is turned off and the Th9, with its current becoming zero, is cooled by natural heat dissipation and automatically restored to its first state after a certain time. Thus a device can be constructed at low cost using a simple circuit.