Phase reference system for cordless looping digitizer

Number of patents in Portfolio can not be more than 2000

United States of America Patent

PATENT NO 5235142
SERIAL NO

07760563

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ATTORNEY / AGENT: (SPONSORED)

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Abstract

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In a cordless, electro-magnetic digitizing system having a drive circuit outputting a square wave drive signal of known initial polarity to a transducer coil in a cursor to oscillate the transducer coil and cause a magnetic field output therefrom which is detected in an associated tablet, a method of operation and associated apparatus for determining the phase of a response signal induced by the magnetic field from the response signal itself. The method comprises the steps of, outputting bursts of a square wave drive signal of known initial polarity to the transducer coil; outputting a signal indicating the start of each burst to the transducer coil; additively outputting a single large current square wave signal pulse to the transducer coil of the same polarity and in phase with a first square wave pulse of the square wave drive signal when initially outputting a burst of the square wave drive signal to the transducer coil whereby additive initial drive currents cause the transducer coil to oscillate immediately and produce a detectable first half-wave in a response signal in the tablet; and, employing the first half-wave of the response signal of known polarity to determine the phase.

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Patent Owner(s)

Patent OwnerAddress
GTCO CORPORATION7125 RIVERWOOD DRIVE COLUMBIA MD 21406

International Classification(s)

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Inventor(s)

Inventor Name Address # of filed Patents Total Citations
Landmeier, Waldo L Phoenix, AZ 16 634
Watson, James S Phoenix, AZ 13 330

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