| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of such a case that an on board battery carelessly becomes an over-discharging state by surely breaking a main power source circuit for a main control means when the operation of the main control means becomes unnecessary. SOLUTION: A main power source circuit 4 for a navigation control computer 9 is fed with electricity from an onboard battery 2 through a power switch circuit 5 and a backup power source circuit 6 is directly fed with electricity from the battery 2. An ACC switch signal detecting circuit 7 outputs a detect signal Sd when an accessory switch 3 is turned on. A power supply control circuit 12 which is fed with electricity from the backup power source circuit 6 outputs a power supply 'ON' command signal Son for turning on the power switch circuit 5 in a state where the detect signal Sd is outputted and a power supply 'OFF' command signal Soff when the output of the detect signal Sd is stopped. A safety circuit 13 validates the command signal Son in a state where the detect signal Sd is outputted, but invalidates the signal Son when the output of the detect signal Sd is stopped. |
