초록 ▼

A power source device capable of using both an external DC power source and a battery contained therein, and an electronic device using this power source device. A circuit is provided to measure the battery voltage, to calculate the remaining capacity of the battery and to indicate the remaining cap

A power source device capable of using both an external DC power source and a battery contained therein, and an electronic device using this power source device. A circuit is provided to measure the battery voltage, to calculate the remaining capacity of the battery and to indicate the remaining capacity. Means is provided which detects the state where no battery is mounted in the power source device, and short-circuits the input side of the battery voltage-measuring circuit. When no battery is mounted, therefore, a voltage leaking from the external DC power source is not erroneously measured as the battery voltage, and the remaining amount of power of the battery is correctly calculated.

대표청구항 ▼

A power source device comprising: first input terminals for connection to an external DC power source; output terminals; second input terminals for connection to a battery; a blocking diode, connected between said output terminals and the second input terminals, said blocking diode preventing a flow

A power source device comprising: first input terminals for connection to an external DC power source; output terminals; second input terminals for connection to a battery; a blocking diode, connected between said output terminals and the second input terminals, said blocking diode preventing a flow of current from the external DC power source to the second input terminals via the first input terminals; a voltage-measuring circuit for measuring a voltage across the second input terminals; a battery mount detecting means for detecting that a battery is connected to the second input terminals; and control means for short-circuiting the second input terminals when it is detected by the battery mount detecting means that a battery has not been connected to the second input terminals.