PURPOSE: To eliminate malfunction of a logical operation processing device even when battery voltage is dropped during electrically energizing an intercepting valve by supplying the logical operation processing device with an electric source through a backup circuit.
CONSTITUTION: An interception judging unit 9 is equipped with the backup circuit 10 and the electric source is supplied from a battery 8 to a micro-computer 6 through the backup circuit 10. The backup circuit 10 consists of a series circuit of a resistor 11 and a capacitor 12. In said constitution, the battery voltage drops to a voltage VB2 during conducting the intercepting valve 4 while the electric source voltage VM of the micro- computer 6 drops from the voltage VB1 at a time before conducting the intercepting valve 4. When the voltage VM1 is higher than a micro-computer operable minimum voltage VDMin, the micro-computer can be operated. This condition may be realized easily by selecting the time constant of CR properly. Here, C is the electrostatic capacity of the capacitor 12 and R is the value of resistance of the resistor 11. The malfunction of the micro-computer due to the electric source voltage drop, which can be caused during conducting the intercepting valve, may be prevented by only adding the backup circuit or a CR time constant circuit having such very simple constitution.
SAKA TATSUO
UNO TAKASHI
KOUNO HIROYUKI
FUJIMOTO TATSUO
KITAJIMA SATORU
HONMA ISAO
TOKYO GAS CO LTD
| JPS57140981A | 1982-08-31 |
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