Fujitsu Corporation

Mituo Saeki

Hidekiyo Ozawa

Hidetoshi Yano

Masafumi Okumura

Tsutomu Suzui

Takeshi Kubo

Hisafumi Mitsui

A charging-and-discharging device in an electronic apparatus includes a rechargeable battery and a charging device for charging the battery. The charging-and-discharging device includes a switching circuit electrically isolating one terminal side of the battery from a ground side of the electronic apparatus. The charging-and-discharging device further includes a charge control section controlling the isolating of the one terminal side of the battery from the ground side of the electronic apparatus by turning off the switching circuit during charging of the battery. In the charging-and-discharging device, the one terminal side of the battery is isolated from the ground side of the electronic apparatus by the switching circuit during charging of the battery and a closed loop including the charging device and the battery is established to charge the battery.

Charging-and-discharging device for an electronic apparatus, and an

Charging-and-discharging device, constant-voltage and constant-current

A power supply device includes a secondary battery and a charger, and can further utilize an external D.C. power supply. A switch is interposed between a negative electrode of the secondary battery and the ground. This switch is turned OFF when the external D.C. power supply is connected to the power supply device, and is turned ON when the external D.C. power supply is removed from the power supply device. The charger controls the charge of the secondary battery from the external D.C. power supply by regulating the potential of the negative electrode of the battery. A contact remains OFF while the external D.C. power supply is connected to the power supply device. In consequence, a current does not directly flow from the external D.C. power supply to the secondary battery. Therefore, a back-flow prevention diode, which otherwise results in power consumption, need not be disposed between the secondary battery and the load.

Power supply device having low internal power consumption and electronic

Charging-and-discharging device, battery pack and electronic apparatus

Charging-and-discharging control device, a battery pack, and an

A power supply apparatus includes a battery, a voltage converter for converting the output of the battery to a different D.C. voltage by ON/OFF action of a main voltage converter control switch circuit, and a device for estimating a remaining capacity of the battery. The remaining battery capacity estimation device detects a non-load voltage of the battery when the main voltage converter control switch circuit is OFF, and estimates the remaining capacity of the battery.

Power supply apparatus and electronic appliance equipped with the power

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.

Remove power source device having improved capacity indication

A booster type DC-DC conversion circuit and a voltage reduction type DC-DC conversion circuit are connected in series with a battery. When battery voltage is high, the booster type DC-DC conversion circuit does not operate, and the voltage reduction type DC-DC conversion circuit outputs a constant voltage lower than the battery voltage. When the battery voltage drops, the booster type DC-DC conversion circuit operates, and converts the battery voltage to a constant voltage higher than the operation voltage of the voltage reduction type DC-DC conversion circuit. The voltage reduction type DC-DC conversion circuit outputs a constant voltage. The power supply apparatus can continuously output a constant voltage from when the battery voltage is high until it becomes low, and can efficiently utilize the battery capacity.

Power supply apparatus for efficiently utilizing battery and electronic

A heating element, such as a switching transistor, a choke coil, or the like, contained in a power supply apparatus, is arranged in such a manner as to be thermally coupled to a diode inserted in series with a power supply line. The heating element heats up in operation, causing the diode temperature to rise and thereby reducing the diode forward voltage drop.

Growing community of inventors

Kawasaki, Japan

Mituo Saeki