Humidity sensing circuit
US5757195A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 19, 1996 |
| Grant date | May 26, 1998 |
| Priority date | — |
| Expiry date | Jul 19, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/225
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A humidity sensing circuit uses a humidity sensitive capacitor as a circuit element in an RC control network for a timer/multivibrator circuit. As the voltage on one plate of the capacitor swings between charge and discharge voltage limits and corresponding triggering voltage values for the timer/multivibrator, the other plate of the capacitor is held at a voltage substantially midway between the charge/discharge voltage limits to thereby cancel out any time averaged net DC component on the capacitor, to reduce stress thereon and extend its life. A power-down feature is disclosed for removing all voltage across the capacitor between sensing intervals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.