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. 25, 1997
Filed:
Apr. 06, 1994
James A Kriewall, Saratoga, CA (US);
Edwin F Johnson, Sunnyvale, CA (US);
Alan R Selfridge, Los Gatos, CA (US);
John P Fairbanks, Sunnyvale, CA (US);
Verne H Wilson, Belmont, CA (US);
Robert W Parry, Santa Cruz, CA (US);
James D Cummins, Union City, CA (US);
Fujitsu, Ltd., Tokyo, JP;
Abstract
A digitizer uses acoustic waves originating from a stylus to determine the position of the stylus on a plate. The acoustic waves are introduced into the plate from the tip of the stylus and are detected by a plurality of detectors positioned at various points along the periphery of the plate. By sensing differences in the arrival times of the acoustic waves at the detectors, a microprocessor calculates the position of the stylus. In a preferred embodiment using a non-tethered stylus, four detectors are positioned at the corners of a rectangle, and the time differences are used as addresses in a lookup table, which is programmed to contain x and y coordinates corresponding to the time differences, Different embodiments may detect only the 'fast' symmetrical waves or only the 'slow' antisymmetrical waves generated in the plate, or may use the arrival times of both types of waves to determine the stylus position.