Hitachi, Ltd.

Tagasangyo, Ltd.

Yasuhiro Tsukamoto

Kozo Tamura

Akira Iida

Syoichi Nihira

Toshiharu Kodato

A charging circuit comprises a main circuit for charging a battery and a power unit connected to an electric power source. The main circuit and the power unit are connected through a connector to each other. The power source transformed by a transformer located at the power unit is supplied to the connector through a contact of a direct current relay. After alternating current is introduced to the main circuit from the power unit, the alternating current is rectified by a diode bridge. The direct current from the diode bridge is supplied to the battery through a control circuit. When the battery is charged sufficiently, the control circuit outputs an instruction signal to a diode portion of a photo-triac connected between an output terminal of the diode bridge and the control relay. When the instruction signal is transmitted to the diode portion, a triac portion of the photo-triac, which is connected between one of an input terminal of the diode bridge and the connector, outputs another instruction signal to the relay located at the power unit for opening the contact through the connector.

Charging circuit

There is provided a power supply apparatus for charging-type device including a transformer disposed in a main body of the power supply apparatus, current supply connection terminals connected to a secondary winding of the transformer, current receiving connection terminals so disposed in a charging-type device as to be capable of being coupled to and detached from the current supplying connection terminals, a storage battery so disposed in the charging-type device as to be charged from the current receiving connection terminals, and a load connected to the storage battery, the power supply apparatus for charging-type device comprising relay contacts of a relay connected to a primary side of a primary winding of the transformer, short-circuit contacts for the relay contacts, a relay coil for opering and closing the relay contacts, a first connection control terminal connected to the relay coil, and a second connection control terminal capable of being coupled and detached from the first connection control terminal, the relay coil being connected to a secondary side of secondary winding of the transformer via the first and second control terminals to interrupt a current flowing through the transformer upon completion of battery charging and upon detachment of the charging-type device from the main body of the power supply apparatus.

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Hitachi, Japan

Yasuhiro Tsukamoto