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. 21, 1978
Filed:
Feb. 26, 1976
Takuji Mukaemachi, Yokohama, JA;
Tetsuo Takeshita, Yokohama, JA;
Tatsuru Miyoshi, Fujisawa, JA;
Takafumi Kojima, Yokohama, JA;
Hitachi, Ltd., , JA;
Abstract
A speech path system for a telephone exchange having crosspoint switches of a speech path network comprising semiconductor switching devices of four or more layers, including a memory circuit for storing the operating conditions of said switching devices, a drive circuit of a high A.C. impedance for actuating said switching devices in response to output signals from said memory circuit, a subscriber D.C. loop detection circuit of a high impedance provided at a subscriber terminal of said speech path network, and a speech current supply circuit with speech current switching means and a supply current detection circuit provided at a trunk terminal of said speech path network.