| 摘要 |
PURPOSE:To always satisfy the startability of a discharge lamp when a power supply mode is changed over from a normal supply mode to a power failure mode, and to prevent the discharge lamp from being blackened and from lowering its service life. CONSTITUTION:A discharge lamp 25 is connected to an a. c. power source 21 through a stabilizer 22 and change-over switches 23a, 23b, 24a, 24b. An inverter circuit 27 is connected to a battery 26, and further is connected to two ends of a secondary winding of a transformer 30 in the inverter circuit through the normally closed side of relay contacts 33a, 33b and the change-over switches 23a, 24a while is connected between intermediate taps t1, t3 of the secondary winding through the normally open side of the relay contacts and the change- over switch, 23a, 24a. Further, the discharge lamp is connected between intermediate taps t2, t4 of the secondary winding through the intermediary of the change-over switch 23b, 24b. A relay 33 is connected to the battery through a phototransistor 32 for detecting whether the discharge lamp is turned on or not. |
