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. 02, 1977
Filed:
Jun. 29, 1976
Youssef Alfred Geadah, Ottawa, CA;
Frank Joseph Vallo, Ottawa, CA;
Northern Telecom Limited, Montreal, CA;
Abstract
A telecommunications terminal apparatus, connected to a transmission facility which includes a source of energizing current and an earth connection, is protected from static discharge of the type typically originating with a user. The terminal apparatus includes an ABS housing with one or more apertures therein to facilitate user actuation of various control buttons or keys. The periphery of each aperture is rendered electrically conductive. A low impedance sink such as a remote power supply, earth or a transmission line is connected to the electrically conductive periphery via a variable impedance element, for example a pair of back to back zener diodes. The housing also includes a conductive foot for contact with a supporting surface. The conductive foot is also connected with the conductive periphery of the aperture. In the case where the electronic circuitry includes a CMOS integrated circuit, an anti-latch circuit is included to prevent destruction of the CMOS integrated circuit which could otherwise be induced by a nearby static electrical discharge.