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:
May. 16, 1989
Filed:
Mar. 20, 1987
Henry G Matthews, Haddam, CT (US);
Thomas Zalenski, Killingworth, CT (US);
Jamie L Barbetti, Milford, CT (US);
Al Mletzko, Woodbury, CT (US);
Summagraphics Corporation, Fairfield, CT (US);
Abstract
A conventional three-electrode wedge-and-strip pattern in a digitizer tablet surface is used with a conventional cursor or stylus. A phantom cursor electrode is located at predetermined coordinates of the active area of the digitizer tablet beneath the X, Y and balance (B) electrodes and separated therefrom by a layer of dielectric material, preferably an air gap. Prior to use of the digitizer apparatus, the phantom cursor electrode is electrostatically coupled to the X, Y and B electrodes in order to obtain data signals representing the phantom cursor's measured coordinates without compensation for resolution distortion. A microprocessor produces a correction factor using the data signals and the predefined coordinates of the phantom cursor electrode, which correction factor is applied in normal use to compensate for resolution distortion resulting from the unavoidable gaps between the X, Y and B electrodes. Also raw measured data obtained from the electrostatically coupled electrodes is adjusted to compensate for environmental and inherent noise and an offset corresponding to the difference in the reference potentials of the integrator and comparator.