Keyboard encoding
US5450080A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 22, 1992 |
| Grant date | Sep 12, 1995 |
| Priority date | — |
| Expiry date | Apr 22, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/96
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A keyboard interface controller in the nature of a state machine is placed in a stop mode or an idle mode after initialization. In stop or idle mode, all the keyboard conductors associated with the X-axis are activated, while all keyboard conductors associated with the Y-axis are sensed. Upon being awakened by an interrupt upon key closure from which the Y-axis location of the closed key is determined, the controller sequences through the steps of (a) determining the X-axis of the keyboard by activating the determined Y-axis conductor and sensing the X-axis conductors; (b) converting the crosspoint to a unique code; (c) transmitting the crosspoint code to the host; and (d) checking for either another closure or the release of the closure detected. When all keys are released, the controller returns to stop or idle mode.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.