Self-compensating thermocouple reading circuit
US4130019A · kind A · utility
Inventor
Key dates
| Filing date | Jun 9, 1977 |
| Grant date | Dec 19, 1978 |
| Priority date | — |
| Expiry date | Jun 9, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01K1/026
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A plurality of thermocouples are connected to reading circuit conductors at an isothermal junction block, for selective connection to the input of an operational amplifier. The resulting output signals from the operational amplifier are monitored and stored in a computer. A reference thermocouple is selectively connected to the operational amplifier through a reference junction compensator -- the reference junction compensator provides a compensated connection of the reference thermocouple with the reading circuit conductors. The signal at the output of the operational amplifier when the reference thermocouple is connected at the input is also monitored by the computer and stored for processing. In the computer, the signal sensed and stored when the reference thermocouple is connected to the operational amplifier is subtracted from the sensed, stored signals generated when the other thermocouples are connected to the operational amplifier. This subtraction nullifies the offset error of the operational amplifier (and the offset error of other reading circuit electronics such as the multiplexer selectively connecting the thermocouples to the operational amplifier), and it corrects th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.