Digitizer with overlapped loop pattern and peak phase recognizer

Claim 1

A digitizer for determining the position of a stylus or cursor, said digitizer comprising: a microprocessor for controlling the digitizer; a quartz oscillator responsive to said microprocessor; an overlapped loop assembly defining an induction area, said overlapped loop assembly comprising a plurality of overlapping loops for a horizontal axis and a plurality of overlapping loops for a vertical axis, each of said plurality of overlapping loops comprising a first turn in one direction and a second turn in an opposite direction, said first and second turns being distanced from one another by a distance equal to half the horizontal distance across the induction area in the case of said overlapping loops for the horizontal axis, and by a distance equal to half the vertical distance across the induction area in the case of said overlapping loops for the vertical axis; a decoder responsive to said microprocessor, for selectively scanning said induction area; an X-axis multiplexer responsive to said decoder, for selecting signals from said overlapped loop assembly; a Y-axis multiplexer also responsive to said decoder, for selecting signals from said overlapped loop assembly; signal amplification means for amplifying signals selected by said X-axis multiplexer and said Y-axis multiplexer; a peak phase recognizer responsive, through said signal amplification means, to said signals selected by said X-axis multiplexer and said Y-axis multiplexer; an analog-to-digital converter responsive, through said signal amplification means, to said signals selected by said X-axis multiplexer and said Y-axis multiplexer; said microprocessor being responsive to outputs from said analog-to-digital converter and from said peak phase recognizer.