Garbling the identification of a key of a non-coded keyboard, and circuit for performing the method
US5254989A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 8, 1991 |
| Grant date | Oct 19, 1993 |
| Priority date | — |
| Expiry date | Jul 8, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F21/83
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A garbling method for 9 non-coded matrix keyboard, and the circuit for performing the method. includes PA1 a) connecting at the output each row and column of the keyboard to the outputs of a first register (160) of a parallel to the outputs of a first register (160) of a parallel input-output interface (16), via a circuit (163, 166, 164); PA1 b) connecting each row and column of the keyboard to the individual inputs of a second register 162 of the input-output interface. PA1 c) randomly setting the order in which the outputs of the first register will be scanned; PA1 d) setting at least one of the outputs of the first register at "1" and checking whether one of the corresponding inputs of the second register is at "1"; PA1 e) if not, scanning the remaining lines one by one by placing them each at "1" until the associated input is at the value "1"; PA1 f) repeating steps d) and e) to determine the column or row respectively, corresponding to the key of the keyboard that has been depressed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.