| 摘要 |
<p>PURPOSE:To generate a warning when a predetermined time is reached by computing time at which a power source voltage lowers to a reference voltage from a drop in voltage of a battery power source after a fixed time measured passes and a difference between a power source voltage and the reference voltage after the passage of a fixed time. CONSTITUTION:System control circuit controls the measuring, computing and warning of a power source voltage. First, the counting of time is started after the passage of a fixed time is checked and a battery voltage is inputted to measure a voltage by A/D conversion thereof. The power source voltage at this moment is compared with a reference voltage and when it is larger, a power reduction flag is checked. When the flag is H, a returning is made or when it is L, the present voltage drop is calculated from the preceding voltage and a difference between the present voltage and a power source OFF voltage is calculated as remaining voltage. Then, a remaining time is calculated from the remaining voltage and the voltage drop and when the remaining time is smaller than a scheduled alarm time, an alarm display demand and a battery voltage reduction flag are set to complete a processing. Thus, time is determined accurately until the operation of a battery is disabled thereby enabling the keeping of usable time constant after a warning.</p> |
