Adaptive frequency touchscreen controller employing digital signal processing
US6473075B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 29, 1999 |
| Grant date | Oct 29, 2002 |
| Priority date | — |
| Expiry date | Sep 29, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/0436
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for adapting an acoustic touchscreen controller to the operating frequency requirements of a specific touchscreen are provided. The adaptive controller can either utilize look-up tables to achieve the desired output frequency or the it can use a multi-step process in which it first determines the frequency requirements of the touchscreen, and then adjusts the burst frequency characteristics, the receiver circuit center frequency, or both in accordance with the touchscreen requirements. In one embodiment, the adaptive controller compensates for global frequency mismatch errors. In this embodiment a digital multiplier is used to modify the output of a crystal reference oscillator. The reference oscillator output is used to control the frequency of the signal from the receiving transducers and/or to generate the desired frequency of the tone burst sent to the transmitting transducers. In another embodiment that is intended to compensate for both global and local frequency variations, the adaptive controller uses a digital signal processor. The digital signal processor, based on correction values contained in memory, defines a specific center frequency which pref…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.