Proportional temperature controller
US3946200A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 24, 1975 |
| Grant date | Mar 23, 1976 |
| Priority date | — |
| Expiry date | Feb 24, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05D23/1913
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A temperature controller for use with an electrical heater for precisely maintaining the temperature within a system at a selected set point, and employing an improved bridge circuit. A temperature sensitive resistor forms one of the two variable arms of the bridge circuit. The resistor varies in value as a function of temperature exhibiting a temperature coefficient of resistance which is not constant but which varies, decreasing with increasing temperature. The other variable arm, the setting arm, is in the form of a network, including a linear setting resistor and a pair of fixed resistors arranged in a series-shunt circuit. The setting resistor is linearly calibrated in terms of temperature, the series-shunt arrangement providing a composite resistance-set point temperature characteristic which closely corresponds to that of the sensing arm. The temperature controller further includes an operational amplifier which provides an output signal dependent upon the degree of bridge imbalance and a zero voltage switch responsive to the operational amplifier for providing trigger pulses to a triac coupled in the load circuit of the heater. A ramp generator is preferably included as a s…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.