| 摘要 |
PURPOSE:To dispense with an adjusting operation due to the irregularity of each circuit, by comparing a battery use time with an initial value time being stored and outputting an alarm when the difference between both times reaches a value within a predetermined range. CONSTITUTION:A microcomputer MPU1 operates an output port 6 to set a control signal 32 to '1' at time t0 and operates a built-in counter. When an analogue signal 31 exceeds battery voltage Vb, the output 33 of a comparator comes t0 '1' and MPU1 stops a counter to read the time T thereof. The time T is the function of battery voltage 30 and said voltage 30 is measured on the basis of the amount of the time T. The time T0 when a battery 9 is set is stored in a memory 3 and, thereafter, when the power source of the apparatus turns ON, times T, T0 are compared if necessary and, at the time of T<T0, the lowering in the voltage 30 is detected to send out an alarm.
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