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:
Mar. 09, 1993
Filed:
Dec. 05, 1989
Robert R Asprey, Harvest, AL (US);
Remigius G Shatas, Huntsville, AL (US);
Cybex Corporation, Huntsville, AL (US);
Abstract
A communications extension link for use between a computer and display unit (K.D.U.) has at the computer site a first interface circuit connected to it and adjacent to the keyboard and display unit a second interface circuit connected to it. The two interface circuits may then be spaced up to 300 feet for a monochrome K.D.U. and up to 150 feet for a color K.D.U. by an extension cable. The first interface circuit includes capacitors connected between keyboard data and clock lines and a positive supply terminal, and TTL buffer amplifiers coupled in single ended configuration are placed in the signal lines relating to video information transmission. The video signals (VS, HS, primary RGB and second rgb) are then each attenuated prior to being passed over the longest cable run, after which they are received by a second interface circuit. The second interface circuit employs discrete resistors between clock and data lines and the positive supply terminal with the attenuated video signals received by discrete buffer amplifiers which amplify the signal and make it compatible with TTL inputs of the monitor. In addition, capacitance is added between the positive supply terminal and logic ground.