| 摘要 |
PROBLEM TO BE SOLVED: To provide an emergency lighting system which charges a secondary battery at normal times and lights a lamp with the secondary battery as a power source in case of emergency, wherein the battery is prevented from being over discharged when a power failure occurs for a long period of time after and electric current is once applied from the commercial power supply. SOLUTION: The emergency lighting system is provided with the secondary battery EB to be charged through a step-down output of the commercial power supply Vs, and lights the lamp La with the secondary battery EB as a power source when the commercial power supply Vs fails. The emergency lighting system further has an electrification detecting circuit for detecting an electric current applied from the commercial power supply Vs. When the current is detected, the secondary battery EB is put in a discharge state. When the predetermined time passes after the power failure, or the battery voltage after the power failure fails below the predetermined voltage level, the secondary battery EB is put in a state where the discharge is prohibited. COPYRIGHT: (C)2003,JPO |
