Extended communications link for keyboard and display units remotely located from a computer
US4885718A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 11, 1987 |
| Grant date | Dec 5, 1989 |
| Priority date | — |
| Expiry date | Sep 11, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/08
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A communications extension link for use between a computer and a keyboard and display unit 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 serveral hundred feet by an extension cable. The first interface circuit includes capacitors connected between keyboard data and clock lines and a positive supply terminal, and buffer amplifiers are placed in the signal lines relating to the display unit. The second interface circuit employs discrete resistors between clock and data lines and the positive supply terminal, and between the vertical sync line and logic ground. In addition, capacitance is added between the positive supply terminal and logic ground.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.