Noncontacting Surface Thermometer for Rollers with Ambient-Temperature Compensation

The noncontacting thermometer for surface temperature measurement of rollers utilizing the radio frequency eddy current effect is described. A type of bridge is employed in this thermometer. The bridge detects a change in the resistivity of a roller material through the radio-frequency measuring coil. This thermometer has considerably improved accuracy with no time lag. The ambient-temperature influence is also compensated for. For example, the sensitivity of this thermometer is in most cases about 10 ¿A per °C, and the error in temperature was kept to less than 1 °C. Control of any arbitrarily desired temperature is possible through the use of this device.