Linearized thermal feedback circuit and temperature controller circuit utilizing the same
US5023431A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 11, 1989 |
| Grant date | Jun 11, 1991 |
| Priority date | — |
| Expiry date | Aug 11, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05D23/24
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A temperature controller for a thermal system comprises a linearized feedback loop. A linearized thermistor and heating element are disclosed. A current source adjusts the bias current of the thermistor so that the thermistor voltage is equal to a given voltage when the thermistor is at the desired temperature. When the thermistor is biased in this way, the incremental gain from temperature errors to thermistor voltage errors becomes independent of set point. The heating element includes a power regulator and a power resistor. Because temperature is a linearly related to the power dissipated in the power resistor, square-law circuitry keeps the voltage output of the power regulator linearly related to the square root of the error in the controlled temperature. In other embodiments of the invention, a voltage source adjusts the bias voltage of the thermistor so that the incremental gain from temperature errors to thermistor current errors is independent of set point.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.