Electronic identification assemblies of capacitive keyboards
US4737768A · kind A · utility
Inventors
Key dates
| Filing date | Apr 29, 1986 |
| Grant date | Apr 12, 1988 |
| Priority date | — |
| Expiry date | Apr 29, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K2017/9613
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An electronic assembly is provided associated with a capacitive keyboard for identifying the depressed keys of this keyboard, which keys are disposed at the intersection points of a checkerboard pattern formed of m lines and n columns, comprising means for successively applying to the inputs of the m lines trains of n successive identical pulses, means for successively collecting at the outputs of the n columns the signals created by these pulses and means for detecting and identifying, among the signals collected, the echoes which exceed a predetermined threshold and which correspond to depressed keys, which means comprise a comparator for comparing the amplitude of said signals with that of a reference voltage. At all times, the comparison reference is related to the average in time of the mean of the amplitudes of the signals received at least two of the column outputs.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.