| 摘要 |
PROBLEM TO BE SOLVED: To realize fail-safe operation for stabilizing a cutoff valve drive, even if the characteristics of the lithium cell vary in the last stage of battery life. SOLUTION: A gas safety circuit of a gas meter is equipped with a secondary power backup element 2 in parallel with a battery 1, and a primary power backup element 6 through a backflow prevention element 5 in the power supplying part of a microcomputer 7. As a result, the system instability caused by the increase of internal resistance at the time of lithium cell end of life can be canceled, enabling to realize the system safety by detecting these excessive characteristics. COPYRIGHT: (C)2005,JPO&NCIPI
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