Self-tuning digitizer control circuit and method
US5191175A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 29, 1991 |
| Grant date | Mar 2, 1993 |
| Priority date | — |
| Expiry date | Jul 29, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/0442
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A self-tuning digitizer control circuit and method which employs a tunable excitation source instead of a tunable front end. In addition, the digitizer control circuit includes a stylus for sensing the excitation signal, and a circuit for processing the information signal from the stylus, including a narrow bandpass filter for passing the frequency of the excitation signal and minimizing the passage of extraneous noise. A controller determines the location of the stylus on the active surface of the digitizer and control operation of the circuit. The excitation source includes, in the preferred embodiment, a tunable divide-by-n circuit employing an 8-bit latch, an 8-bit counter, and a state machine. A nonvolatile memory stores the most recent value for the divisor value n. Provision is also made for a tuning method for the divide-by-n circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.