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:
Aug. 15, 1978
Filed:
Jul. 21, 1976
Applicant:
Inventors:
Assignee:
Hitachi, Ltd., , JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04Q / ; H04K / ;
U.S. Cl.
CPC ...
179 / ; 3072 / ; 3072 / ; 3072 / ; 3401 / ;
Abstract
A plurality of PNPN switches, each permitting current flow in either, i.e., positive or negative, direction, are arranged at the cross points between the rows and the columns of the speech paths so as to form a matrix. The gate trigger terminal of each PNPN switch is connected with a gating current circuit having a high impedance, which circuit is adapted to control ON and OFF operations of the switch. A plurality of means are provided to selectively turn the gate current circuits on and off so that gate current is supplied continuously for the gate terminal of any desired PNPN switch at least for the time during which the corresponding cross point of the matrix is to be electrically bridged.