| 摘要 |
PURPOSE:To make it possible to display the life of a battery by calculating the residual time of the battery at every mode of a portable television, by generating the code corresponding to the voltage of a power source from a voltage detection circuit when the power source is closed. CONSTITUTION:In a portable television having a plurality of modes and equipped with CPU, when a power source switch 27 is turned ON, a one-shot pulse signal PO1 is outputted to a voltage detection circuit 30 and CPU22 from a power source circuit 29. A power source is supplied to each circuit from the power source circuit 29 and the potentials of the anode and cathode of a battery 28 are outputted to a voltage detection circuit 30 which in turn outputs the code signal corresponding to the voltage of the battery 28 to CPU22. In CPU22, the lives of the battery 28, when the portable television is used as a TV mode, an AM mode, an FM mode and a computer mode, are calculated on the basis of the voltage code signal and transmitted to a display memory 24 to be displayed 20 on a liquid crystal panel 21 through a display change-over circuit 19.
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