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:
Feb. 17, 1981
Filed:
Dec. 13, 1978
Dieter Holzmann, Freiburg-Munzingen, DE;
Joachim Grosse, Breisach-Guendlingen, DE;
ITT Industries, Inc., New York, NY (US);
Abstract
A keyboard switch matrix has a plurality of column and row wires and switches having only two poles and no interconnecting diodes for selectively connecting one of said columns to one of said rows. Associated with each column and row wire is a flip-flop having a set input connected to the wire and an electronic switch for each flip-flop connecting a flip-flop output to the set input. The outputs of the row flip-flops are connected to a NOR-gate, the output of which is connected to a control input of the electronic switches associated with the column flip-flops and also to a second set input of the column flip-flops. The output of the NOR-gate is further connected to a control input of the electronic switches associated with the row flip-flops through an inverter. Reset inputs of the column flip-flops are connected to the NOR-gate output through a differentiation circuit which is triggered by a negative pulse edge. A second NOR-gate has its inputs connected to the column wires and provides an output to a differentiation circuit which is triggered by a positive pulse edge. The output of the differentiation circuit is connected to reset inputs of the row flip-flops. Thus, the geometric position of the actuated keyboard switch is stored in the respective row and column flip-flops, and code signals corresponding to said position are provided at the outputs of said flip-flops.