Electricity: battery or capacitor charging or discharging – Battery or cell discharging – With charging
Reexamination Certificate
1999-04-22
2001-05-01
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
With charging
Reexamination Certificate
active
06225783
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a battery pack used as a power source for video cameras, portable telephones or personal computers, a battery charging device for charging the battery pack and a method for charging the battery pack.
Hitherto, there are known battery packs constituted by secondary batteries such as lithium-ion batteries, nickel-cadmium batteries, nickel-hydrogen batteries or the like.
These known battery packs incorporate, for example, a microcomputer for calculating a residual capacity thereof and conducting communications with electronic apparatuses using the battery pack as a power source, peripheral devices, a detection circuit for detecting conditions of a battery cell which are required for the microcomputer to calculate the residual battery capacity, or the like.
In conventional battery charging devices for these battery packs, for example, constituted by lithium-ion batteries, there has been used a constant-voltage charging system in which a predetermined constant voltage is continuously applied when the battery is charged. In addition, the respective battery packs have often been different in charging voltage (which means a maximum charging voltage which can be applied to the battery pack to be charged, and is hereinafter referred to merely as “maximum charging voltage”) per one battery cell depending upon kinds of electrodes used in the respective battery cells. For this reason, many of the conventional battery charging devices have been used only for charging limited kinds of battery packs compatible thereto.
However, from the standpoint of costs, it have been inconvenient to prepare many battery charging devices compatible to various types of battery packs. Accordingly, many of recent battery charging devices are obliged to have such a function by which various types of battery packs having different maximum charging voltages can be charged.
However, such battery charging devices capable of charging plural kinds of battery packs have been so designed, from the viewpoint of safety, as to operate in conditions for charging the battery packs having the lowermost maximum charging voltage among those of all the compatible battery packs. Similarly, the battery charging devices have been so designed as to provide such a charging current (which means a maximum charging current which can flow through the battery pack, and is hereinafter referred to merely as “maximum charging current”) identical to the lowermost maximum charging current among those of all the compatible battery packs.
Thus, in these conventional battery charging devices, it is impossible to equally supply an optimum charging energy to all the compatible battery packs intended, so that there arise inconveniences that 100% charging cannot be attained or it takes a considerably long time to attain 100% charging.
SUMMARY OF THE INVENTION
The present invention has been achieved in view of the afore-mentioned problems. Accordingly, it is an object of the present invention to provide a battery charging device capable of supplying an optimum charging energy to all of a plurality of battery packs intended and a method for charging the battery pack, and the battery pack which can be charged by such a battery charging device and method.
The battery charging device and method according to the present invention are such device and method for charging the battery pack which can store at least an information indicative of the maximum charging current and an information indicative of the maximum charging voltage and communicate the information. In accordance with the present invention, the afore-mentioned problems can be overcome by receiving the information indicative of the maximum charging current and the information indicative of the maximum charging voltage from the battery pack, detecting a current voltage of the battery pack upon charging, changing over a charging condition of the battery pack between a constant-current charge and a constant-voltage charge depending upon the detected current voltage, and controlling the charging of the battery pack so as not to exceed the maximum charging current and the maximum charging voltage.
In addition, the battery pack according to the present invention comprises a battery cell, a memory means for storing an information indicative of a maximum charging current and an information indicative of a maximum charging voltage of the battery cell and a communication means for transmitting the information indicative of the maximum charging current and the information indicative of the maximum charging voltage, thereby overcoming the afore-mentioned problems.
That is, in accordance with the present invention, it is possible to equally supply an optimum charging energy to all of a plurality of battery packs having different maximum charging currents and maximum charging voltages by storing the information indicative of the maximum charging current and the information indicative of the maximum charging voltage on the battery pack, changing over a charging condition of the battery pack between a constant-current charge and a constant-voltage charge depending upon a current voltage of the battery pack when the battery pack is charged, and further controlling the charging of the battery pack so as not to exceed the maximum charging current and the maximum charging voltage.
REFERENCES:
patent: 3617850 (1971-11-01), Domshy
patent: 4387334 (1983-06-01), Loper
patent: 4849682 (1989-07-01), Bauer et al.
patent: 5541496 (1996-07-01), Simmonds
patent: 5633573 (1997-05-01), van Phuoc et al.
patent: 6008620 (1999-12-01), Nagano et al.
Koyama Toshio
Nagano Naoki
Frommer William S.
Frommer Lawrence & Haug LLP.
Sony Corporation
Tso Edward H.
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