Digitizer system with passive pointer
US5045645A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 22, 1990 |
| Grant date | Sep 3, 1991 |
| Priority date | — |
| Expiry date | May 22, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/046
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A driving grid is driven by an ac signal comprising a carrier frequency modulated by a lower frequency. An untethered, batteryless pointer includes a pick-up coil in a first tuned circuit tuned to the carrier frequency, connected by diodes to a driving coil in a second tuned circuit tuned to the lower modulating frequency. Energy picked up by the first tuned circuit from the driving grid at the carrier frequency drives the second tuned circuit at the modulating frequency. Modulating frequency signals induced in the receiving grid conductors are used to locate the pointer in the usual manner. Because the carrier signal contains no frequency component of the modulating signal, the driving grid and receiving grid are sufficiently decoupled.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.