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:
Aug. 10, 1993
Filed:
Sep. 16, 1991
Waldo L Landmeier, Phoenix, AZ (US);
James S Watson, Phoenix, AZ (US);
CalComp, Inc., Anahiem, CA (US);
Abstract
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.