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:
Oct. 05, 1976
Filed:
Jan. 20, 1975
Ted W Berwin, Playa Del Rey, CA (US);
Hughes Aircraft Company, Culver City, CA (US);
Abstract
A system is disclosed for generating a circle on a television raster display utilizing digital techniques. An x coordinate counter, a y coordinate counter, a radius number, and a radius +.delta. number, in parallel to each other, are connected to the input terminals of a multiplex switch. The multiplex switch selectively provides an output signal of the above number generators to a programmable read only memory (PROM). The memory in turn sequentially provides an output signal representing the square of the input number, i.e., x.sup.2, y.sup.2, r.sup.2 and (r + .delta.).sup.2. The numbers x.sup.2 and y.sup.2 are added by an adder and the number x.sup.2 + y.sup.2 is compared by a first comparator, with the number r.sup.2 and an output is provided if x.sup.2 + y.sup.2 .gtoreq. r.sup.2. The numbers x.sup.2 + y.sup.2 is also compared by a second comparator, with the number (r+.delta.).sup. 2 and an output signal is provided if x.sup.2 + y.sup.2 < (r+.delta.).sup.2. An output signal is provided to a television display whenever the above equations are true. Thus, each point on a television raster display is tested and a video signal is provided when the equations are both true.