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:
Apr. 28, 1992
Filed:
Dec. 12, 1989
Takashi Sone, Tokyo, JP;
Jun Sato, Musashino, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A color graphic display system is disclosed including a drawing process for displaying video data on a display device wherein the data is particularly intended to include superposed pictures. The processor includes an arithmetical operation unit which will allow addition/subtraction of video data items representative of the picture elements to be superposed. Further included is a condition setting circuit for selectively inhibiting carrys or borrows during the arithmetical operations between selected bits of a data word representative of an element such as a pixel of the picture being displayed. More particularly, where a video data item is comprised of sets of bits each set of which is representative of a main color of the pixel, and when two video data items are added or subtracted, the carrys that may normally occur between the different sets are inhibited to avoid interference between the sets that may affect the color of the resulting video data item. A carry look-ahead circuit is also provided for improved processing speed of the system. An overflow prevention circuit is disclosed for forcibly switching selected bits of the video data item to a preselected value upon determining that an operated result has given rise to an overflow.