Potentiometer setting detection by measuring the ratio of RC time constants
US4864513A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 7, 1987 |
| Grant date | Sep 5, 1989 |
| Priority date | — |
| Expiry date | Jul 7, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R27/02
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The present invention is a technique for forming a signal representing the operator adjustment of a potentiometer. This technique consists of measuring the reference time constant of the resistance between the fixed terminals of the potentiometer and a capacitor, measuring the variable time constant of the resistance of potentiometer between a fixed terminal and the terminal variable by an operator setting and this same capacitor, and again measuring the reference time constant of the resistance between the fixed terminals of the potentiometer and the capacitor. These time constant measurements are made by discharging the capacitor, charging the capacitor through the appropriate terminal of the potentiometer and measuring the time required for the voltage across the capacitor to reach a predetermined threshold level. This measurement sequence is repeated if the two measures of the reference time constant differ by more than a predetermined amount. The digital ratio of the variable time constant and the reference time constant is then calculated. This digital ratio is the representation of the operator adjustment of said potentiometer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.