Coordinate input apparatus with correction of detected signal level shift
US5805147A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 15, 1996 |
| Grant date | Sep 8, 1998 |
| Priority date | — |
| Expiry date | Apr 15, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/0433
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
With the use of transfer delay of supersonic wave, an apparatus for measuring a distance and inputting coordinates accurately is implement. When a distance is measured with the use of the transfer of supersonic wave, the transfer delay time is measured at the specified portion of a detected signal. The position of the specified portion to be measured may shift due to the level of the detected signal or noise. The signal obtained by delaying the specified time the envelope of the detected signal is generated. The signal obtained by attenuating the envelope at the specified rate and adding the specified offset is also generated. A gate signal is formed by obtaining the differential of these two generated signals. The delay time is measured during the gate period. With this configuration, the gate-period timing is immune to influences of the signal level and noise, providing highly precise coordinate inputs.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.