Battery pack charger having a fail-safe heat-sensitive switch for preventing overcharge
First Claim
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1. A battery pack charger comprising:
- an external frame provided with an insertion slot for inserting a battery pack, the battery pack including a battery having a first polarity and a second polarity opposite the first polarity;
a first charging terminal connected to the first polarity of the battery when the battery pack is inserted into the insertion slot;
a second charging terminal connected to the second polarity of the battery when the battery pack is inserted into the insertion slot;
a charging control circuit housed in said external frame, said charging control circuit charging the battery and stopping a charging operation when the battery is fully charged;
a heat-sensitive switch connected between said first charging terminal and said charging control circuit, said heat-sensitive switch disconnecting said charging control circuit from said first charging terminal when said heat-sensitive switch exceeds a predetermined temperature, thereby stopping the charging operation even if said charging control circuit fails to stop the charging operation;
a first lead wire connecting said first charging terminal and said heat-sensitive switch, said first lead wire having a length that does not substantially lose heat transferring from the battery pack to said heat-sensitive switch along said first lead wire; and
a second lead wire connecting said second charging terminal and said charging control circuit.
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Abstract
A battery pack charger has an external frame provided with an insertion slot for inserting a battery pack. A charging terminal and a charging control circuit are housed in the external frame. A heat-sensitive switch is provided between the charging terminal and the charging control circuit. A lead wire is provided between the charging terminal and the heat-sensitive switch. The lead wire has a length appropriate for not losing the effect of heat transferred along the lead wire. The battery pack charger is capable of reliably charging a battery pack without the occurrence of overcharge, even if the battery pack is not provided with a heat-sensitive switch.
14 Citations
13 Claims
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1. A battery pack charger comprising:
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an external frame provided with an insertion slot for inserting a battery pack, the battery pack including a battery having a first polarity and a second polarity opposite the first polarity; a first charging terminal connected to the first polarity of the battery when the battery pack is inserted into the insertion slot; a second charging terminal connected to the second polarity of the battery when the battery pack is inserted into the insertion slot; a charging control circuit housed in said external frame, said charging control circuit charging the battery and stopping a charging operation when the battery is fully charged; a heat-sensitive switch connected between said first charging terminal and said charging control circuit, said heat-sensitive switch disconnecting said charging control circuit from said first charging terminal when said heat-sensitive switch exceeds a predetermined temperature, thereby stopping the charging operation even if said charging control circuit fails to stop the charging operation; a first lead wire connecting said first charging terminal and said heat-sensitive switch, said first lead wire having a length that does not substantially lose heat transferring from the battery pack to said heat-sensitive switch along said first lead wire; and a second lead wire connecting said second charging terminal and said charging control circuit. - View Dependent Claims (2, 3, 4, 5)
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6. A battery pack charger comprising:
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an external frame provided with an insertion slot for inserting a battery pack, the battery pack including a battery having a first polarity and a second polarity opposite the first polarity; a first charging terminal connected to the first polarity of the battery when the battery pack is inserted into the insertion slot; a second charging terminal connected to the second polarity of the battery when the battery pack is inserted into the insertion slot; a charging control circuit housed in said external frame, said charging control circuit charging the battery and stopping a charging operation when the battery is fully charged; a heat-sensitive switch connected between said first charging terminal and said charging control circuit, said heat-sensitive switch disconnecting said charging control circuit from said first charging terminal when said heat-sensitive switch exceeds a predetermined temperature, thereby stopping the charging operation even if said charging control circuit fails to stop the charging operation; a first lead wire connecting said first charging terminal and said heat-sensitive switch; and a second lead wire connecting said second charging terminal and said charging control circuit, wherein heat channels are provided that minimize heat loss when heat generated from said battery and said charging control circuit is transferred to said heat-sensitive switch. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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Specification