| 摘要 |
PROBLEM TO BE SOLVED: To provide a lighting device for emergency reduced in size without raising cost. SOLUTION: When commercial alternating-current power (e) is off, neither of zener diodes ZD1, ZD2 are turned on, thereby turning off a transistor Q1. A transistor Q4 is turned off, no exciting current flows through a relay coil RyL1 of a direct-current relay Ry, relay contacts RyS1, RyS2, RyS3, RyS4 electrically separate an inverter circuit 11 from a fluorescent lamp FL, while they connect an inverter circuit 15 to the fluorescent lamp FL. A base current is supplied to a transistor Q3, and the transistor Q3 is turned on, thereby actuating the inverter circuit 15. The inverter circuit 15 can be prevented from operating before the relay makes contact with RyS1, RyS2, RyS3, RyS4 separate the inverter circuit 11 from the fluorescent lamp FL, and a high voltage from the in verter circuit 15 can be prevented from being impressed on the relay contacts RyS1, RyS2, RyS3, RyS4. There is no necessity for making the relay contacts RyS1, RyS2, RyS3, RyS4 resistant to high voltages, and their size and cost can be reduced. |
