Calcomp Inc.

Brian L Abernethy

Jason J Hoendervoogt

A cordless transducer/cursor having a transmitter for use in conjunction with the receiver of a digitizer tablet. The transmitter receives parallel binary signals representing the status of non-positional functions such as command button status and the pressure applied to a stylus of the transducer/cursor and converts these into a serial stream of binary data for electrostatic or electromagnetic transmission to the receiver which, in turn, converts the serial stream into a plurality of parallel binary signals consistent with those received and converted by the transmitter.

Cordless digitizer transducer/cursor status transmission apparatus and

An integrated voltage controlled oscillator (VCO) circuit which utilizes the relative capacitance ratio between capacitors and the relative resistance ratio between resistors in an integrated circuit (IC) to output a signal having a predictable frequency for a given control signal voltage. The VCO output frequency will not vary more than 3.0% from one IC chip implementing the VCO circuit, to the next. This low variance between IC chips is derived from the phenomenon whereby the respective ratios of capacitance and resistance between capacitors and resistors in the IC will not vary more than .+-.1.5% from the ratios of like capacitors and resistors on other IC chips. The integrated VCO circuit includes a control signal subcircuit, integrator subcircuit, filter subcircuit, and comparator unit subcircuit.

Voltage controlled oscillator circuit employing integrated circuit

A driving grid is driven by an ac signal comprising a carrier frequency modulated by a lower frequency. An untethered, batteryless pointer includes a pick-up coil in a first tuned circuit tuned to the carrier frequency, connected by diodes to a driving coil in a second tuned circuit tuned to the lower modulating frequency. Energy picked up by the first tuned circuit from the driving grid at the carrier frequency drives the second tuned circuit at the modulating frequency. Modulating frequency signals induced in the receiving grid conductors are used to locate the pointer in the usual manner. Because the carrier signal contains no frequency component of the modulating signal, the driving grid and receiving grid are sufficiently decoupled.

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Pheonix, AZ, United States of America

Brian L Abernethy