Line switching circuit for cordless telephone

Number of patents in Portfolio can not be more than 2000

United States of America Patent

PATENT NO 4691338
SERIAL NO

06908573

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ATTORNEY / AGENT: (SPONSORED)

Importance

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Abstract

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A line switching circuit for a communications system which includes a cordless telephone and gives priority of use to an ordinary telephone associated with the cordless one is disclosed. The circuit includes a current detector for detecting a current which flows through the telephone, a circuit having a time constant on only one of positive going edges and negative going edges of an output of the current detector, a relay interposed between the cordless telephone and a subscriber's telephone line, and a driver for driving the relay. The relay is closed immediately upon change of the telephone from an off-hook state to an on-hook state and opened with a predetermined time constant upon change of the same from an on-hook state to an off-hook state, whereby a hand-over of conversation between the telephones may be effected without any malfunction even if a ringing signal from a central office is received.

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Patent Owner(s)

  • NEC CORPORATION

International Classification(s)

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Inventor(s)

Inventor Name Address # of filed Patents Total Citations
Makino, Masayuki Tokyo, JP 14 286

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