Digitizer system with loopback conductor grid
US4734546A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 16, 1987 |
| Grant date | Mar 29, 1988 |
| Priority date | — |
| Expiry date | Mar 16, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/046
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In a digitizer system, adjacent conductors in pairs are looped through four quarter sections of a grid active area in such a way that the unexcited polarities of the pair are different in each quarter section. A coil in a pen tip is moveable relative to the grid, and used to inductively couple signals in the conductors of the grid. The number of conductors required to span a given grid active area, and the number of multiplexers required to handle such conductors, are reduced by a factor of four. The polarities of signals induced in the conductors by the coil are selectively changed depending upon the quarter section in which the coil is located and sampled to coarsely locate the coil as being between two particular adjacent conductors. In the disclosed embodiment, a ratio of the magnitudes of the signals induced in the two particular conductors is then used to precisely locate the coil between these two adjacent conductors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.