Method and apparatus for detecting switch closures

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United States of America Patent

PATENT NO 6970752
SERIAL NO

09573987

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ATTORNEY / AGENT: (SPONSORED)

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Abstract

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An apparatus and method for detecting the closure of one of several switches using a single input line of a detector is disclosed. The input line is also used to carry an audio-frequency signal when a recording switch is closed. The switches are connected to a network of resistors that cooperate with a pull-up resistor to form a voltage divider. The pull-up resistor is connected to the input line. The switches are closed to selectively switch resistors in the network out of the voltage divider to change the voltage on the input line. A detector reads the voltage on the input line and compares it with a set of predetermined values to determine which switch is closed. If a recording switch is closed, a microphone connected to the network of resistors converts sound to an audio-frequency signal onto the input line.

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Patent Owner(s)

Patent OwnerAddress
HEWLETT-PACKARD DEVELOPMENT COMPANY L P10300 ENERGY DRIVE SPRING TX 77389

International Classification(s)

Inventor(s)

Inventor Name Address # of filed Patents Total Citations
Lim, Teck Chye Allen Singapore, SG 3 52
Tan, Khiam Yong Singapore, SG 4 58

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