Scanning system for touch screen keyboards
US5355149A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 27, 1992 |
| Grant date | Oct 11, 1994 |
| Priority date | — |
| Expiry date | May 27, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/0421
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A touch screen control system having a plurality of light emitter and detector pairs positioned on opposite sides of a touch screen display. The emitters and detectors are controlled by a microprocessor-based control system that energizes each of the light emitters in a pseudorandom manner. Before each light emitter is energized, the intensity of ambient light is measured by its associated light detector, and the ambient temperature is also measured by a temperature sensor. The intensity at which the light emitter is then energized is controlled as a function of ambient light and temperature. The control system generates a bitmap identifying beams from each light emitter to its associated detector that are obscured during each of several scans of the light emitter/detector pairs. In order to reject false receptions of light from an obscured light emitter beam, the control system processes the bitmap through a predetermined voting procedure. The control system is thus able to minimize the effect of interfering light sources on the performance of the touch screen.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.