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. 01, 1990
Filed:
Nov. 23, 1988
Applicant:
Inventor:
Sadakazu Shiga, Iwaki, JP;
Assignee:
Alps Electric Co., Ltd., Tokyo, JP;
Attorneys:
Primary Examiner:
Int. Cl.
CPC ...
G06F / ;
U.S. Cl.
CPC ...
341 25 ; 341 24 ; 341 26 ;
Abstract
A keyboard with N-key rollover has a matrix of key columns and lines for successively issuing key codes for depressed keys. When first and second keys on the same column are detected as being depressed and then a third key on the same line as one of the first and second keys is detected as being depressed, or when first and second keys on the same line are detected as being depressed and then a third key on the same column as one of the first and second keys is detected as being depressed, a key code for the third key or a key code for a fourth key detected in error upon depression of the third key are prevented from being issued.