Canon Kabushiki Kaisha

Tsutomu Nishikawa

Isao Hayashi

Akira Fukushima

Takashi Narasawa

A charging device which is capable of preventing charging current from flowing even if a battery pack remains mounted thereon after charging of the battery pack is completed, thereby preventing deterioration of batteries of the battery pack. A circuit including a semiconductor switch generates a DC power for charging the battery pack. A backflow prevention diode is connected between the semiconductor switch and the battery pack. When charging of the battery pack has been completed, a secondary charge control circuit causes a DC voltage input to the backflow prevention diode to be made lower than the voltage of the battery pack.

Charging device with backflow prevention

A charging device includes a charging circuit for performing a charging action on a secondary battery, a power supplying circuit for supplying power to a load device connected to the charging device, a mode change-over circuit for selection from between a charge mode in which the charging action on the secondary battery is performed and a discharge mode in which power is supplied to the load device, and a control circuit for, when the charge mode is selected by the mode change-over circuit, causing the charging circuit to perform the charging action on the secondary battery and for, when the discharge mode is selected by the mode change-over circuit, causing the power supplying circuit to supply power from the secondary battery to the load device in a state in which the secondary battery is mounted on the charging device.

Combination battery charger and battery driven power supply

When charging current is switched, the output voltage from the solar cell, namely an input voltage to a charging apparatus, changes, and controlling the input voltage to the charging apparatus does not operate correctly. Furthermore, when charging current decreases in response to a drop of the output voltage from the solar cell, a fully-charged state of the secondary cell is erroneously detected. Still further, when the charging operation is completed in accordance with a timer after charging the secondary cell by a small charging current, the secondary cell is not fully charged. To correct these problems, the input voltage Vin is compared to a voltage value V1, and, if a state in which Vin is higher than V1 (Vin&gt;V1) is moved to a state in which Vin is equal or lower than the V1 (Vin.ltoreq.V1), a charge mode which supplies small charging current starts, thereafter, the charging current is increased for a short period of time at a predetermined time interval, and then, on the basis of a comparison result between Vin and V1 at this time, the subsequent charge mode is controlled. The charged amount of the secondary cell is obtained by measuring the charging current, and the fully-charged state of the secondary battery is determined on the basis of the obtained charged amount.

Charging apparatus and charging system for use with an unstable

In a charging method and apparatus according to the present invention, after a first charging operation is performed on a secondary battery, a second charging operation is performed subsequently to the first charging operation, whereby the secondary battery can be fully charged irrespective of the charge characteristic of the secondary battery.

Growing community of inventors

Chigasaki, Japan

Tsutomu Nishikawa