Electromagnetic position transducer having active transmitting stylus
US5420379A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 27, 1993 |
| Grant date | May 30, 1995 |
| Priority date | — |
| Expiry date | Apr 27, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/047
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Disclosed is electromagnetic transducer (10) that does not require complex analog to digital, digital to analog converters, microprocessors or large memory circuitry. The transducer has a helical tablet coil (22) with tap nodes (24) spaced between its end extremities (26). In one configuration, an oscillator (42) drives the tablet coil for simultaneously producing oppositely directed currents on opposite sides of selected taps, creating a moving fringing field (34) that is compatible with modern graphic display tablet technology. A control circuit (40) of the transducer has a closed-loop integrator (82, 106) for detecting the centroid of a received stylus signal (AC) from a stylus coil (36). Analog and digital versions of the integrator are disclosed. In another configuration, the oscillator (174, 175, 176, 177) drives the stylus coil (162) for variably coupling magnetic flux to the tablet coil, a receiver signal (190) that is coupled from the end extremities being responsive to the position of the stylus coil and the taps selected. A preferred configuration of the tablet coil has separate oppositely wound coil components ( 22a, 22b).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.