Electronic thermometer

Abstract

Abstract An electronic thermometer comprises a temperature sensitive resistance element to be placed in contact with the area of which the temperature is to be measured. A first relaxation oscillator to which the resistance element belongs, provides a frequency depending on the temperature to be measured. A reference oscillator provides a reference frequency. The first frequency is counted in a counter during a period provided from the reference frequency by a divider. If a temperature or power supply drift affects the reference frequency, the same drift affects in the same direction the counted frequency, so that during the counting the effect of the drift is substantially cancelled. A memory and a comparator record the result of the counting only if it is higher than the preceding result, so that the thermometer operates as a maximum thermometer. The recorded result is provided to a decoder which controls a display device.

Inventors

• 👤 Jean-Marie Bellet

Bibliographic Details