The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 03, 1992
Filed:
Sep. 27, 1991
James S Watson, Phoenix, AZ (US);
Calcomp Inc., Anaheim, CA (US);
Abstract
In an electro-magnetic, cordless digitizer system wherein a transducer emits an AC magnetic field which is detected by a first grid of scanned parallel first wires in a tablet to provide positional data for the transducer in a first axis of a coordinate system and which are detected by a second grid of scanned second wires in the tablet to provide positional data for the transducer in a second perpendicular axis of the coordinate system, a method and associated apparatus for obtaining a phase reference signal; to be used in a demodulator demodulating data signals from the first and second grids of scanned first and second wires. The method comprises the steps of, scanning the first wires to determine ones of the first wires close to a present location of the transducer; connecting to a one of the first wires displaced from the ones of the first wires close to a present location of the transducer a sufficient distance to provide a valid and usable voltage for use in generating a phase reference signal; and, using a voltage from the one of the first wires to generate a phase reference signal to the demodulator when processing data signals from both the first grid of scanned parallel wires and the second grid of scanned wires.