Miniature silicon based thermal vacuum sensor and method of measuring vacuum pressures
US5557972A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 13, 1994 |
| Grant date | Sep 24, 1996 |
| Priority date | — |
| Expiry date | Sep 13, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L21/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A miniaturized silicon based thermally controlled vacuum sensor uses thin film resistors on a membrane in a minute measuring chamber to accurately detect vacuum pressures in the range of 760 Torr to 1.times.10.sup.-5 Torr. The configurations of the measuring chamber and gas diffusion port of the sensor structure insure that heat transfer from the membrane is predominately conductive over the pressure detection range to provide linear output up to 0.1 Torr. A microprocessor is used to control and measure power required to maintain a predetermined temperature differential between a sensing resistive element on the membrane and an ambient temperature sensing element of the sensor base from analog voltage and current values. Pressure detection errors introduced by ambient temperature variations are minimized by measuring power dissipated into the gas. Analog and digital converters for both current and voltage signals use a .SIGMA.-.DELTA. conversion method to reject electrical noise by an averaging technique to produce stable signal detection of pressure down to 1.times.10.sup.-5 Torr. The sensor is thermally stable over an ambient temperature range of 0.degree.-50.degree. C. at pressu…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.