Electronic thermohygrometer with square-wave pulse signal generator
US4816748A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jul 30, 1987 |
| Grant date | Mar 28, 1989 |
| Priority date | — |
| Expiry date | Jul 30, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/122
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An electronic hygrometer and an electronic thermohygrometer both comprising oscillation means and digital operation processing means. The oscillation means of the hygrometer includes a square-wave pulse signal generator, a humidity sensor connected to the generator and which exhibits characteristics variable with the humidity change of the atmosphere, and a passive element connected to the generator and which forms a time constant circuit with the characteristics of the humidity sensor, the passive element being of a type different from the humidity sensor. The oscillation means produces square-wave pulse signals corresponding to changes in the characteristics of the sensor. The digital operation processing means of the hygrometer counts the frequency of the square-wave pulse signals output from the oscillation means and determines the humidity of the atmosphere on the basis of the counted value. The thermohygrometer further comprises a reference resistance element connected in parallel with the humidity sensor, a temperature sensor connected in parallel with the humidity sensor and the resistance element and which exhibits electric resistance variable with the temperature change o…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.