Frequency shifting digitizer for reducing AC fields interference
US4794208A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 8, 1988 |
| Grant date | Dec 27, 1988 |
| Priority date | — |
| Expiry date | Feb 8, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/0383
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A digitizer wherein the transduction frequency is controlled (automatically or manually) to minimize the interference effect of sources of external AC fields, such as CRT monitors. The digitizer implements the method of operation comprising the steps of, connecting a source of a frequency higher than the frequency to be employed as the transduction frequency of the digitizer to the first input of a counter; receiving input pulses from the source at the first input of the counter; outputting output pulses which are employed to generate the transduction frequency in the digitizer at an output of the counter; selectively setting an initial count value at a second input of the counter; and, repeatedly counting from the initial count value at the second input to a terminal value, outputting an output pulse upon reaching the terminal value, and resetting to the initial count value after outputting each output pulse. The preferred automated method includes reading and saving the induced position voltages being employed by the digitizer, testing the saved voltages for any flutter, and setting the initial count value to an optimum level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.