Tablet stacked on LCD read after display line pulse signal in order to avoid impulse noise superposed on the tablet coordinate signal to improve measuring accuracy
US6229528A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 10, 1998 |
| Grant date | May 8, 2001 |
| Priority date | — |
| Expiry date | Nov 10, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F1/3262
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A liquid crystal tablet equipment which allows improvement in accuracy of coordinate measurements by removing undesirable influence of noise caused by line pulse signals applied to a liquid crystal display and allows coordinate measurement in shorter time period includes a liquid crystal display, a liquid crystal display control circuit for applying the line pulse signals at a prescribed interval to each of an array of pixels constituting the liquid crystal display, a tablet stacked on the liquid crystal display, an A/D converter receiving a coordinate signal output from the tablet, a tablet control circuit for calculating coordinate data from a digital signal output from the A/D converter, and a CPU for letting A/D converter output the digital signal after a prescribed time period from a timing of activation of the line pulse signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.