Touch sensing method and apparatus
US5790107A · kind A · utility
272Cited by
12References
18Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 7, 1995 |
| Grant date | Aug 4, 1998 |
| Priority date | — |
| Expiry date | Jun 7, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/0446
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Method and apparatus for determining small variations in capacitance, typically in a capacitive touch sensing device, includes a reference signal of a first frequency and a sample signal of a second frequency. The reference and sample signals are mixed and filtered to isolate the beat frequency therebetween, which is then measured to provide an indication of the variation in the sample frequency. The measurement can then be manipulated by a microprocessor or microcontroller to provide desired control signals. The apparatus is susceptible of digital implementation and single chip implementation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.