| 摘要 |
PURPOSE:To realize a temperature converter whose entire constitution is simple by constituting a microcomputer and its peripheral circuits as a hybrid IC, putting it in a thermocouple terminal box, and connecting the terminal box and a receiving terminal by a two-wire signal line. CONSTITUTION:A thermo-electromotive force from a thermocouple TC and a temperature signal generated by a diode D1 are amplified A1 and A2, selected alternately by an analog switch AS, and A/D-converted AD, and the conversion results is inputted to the microcomputer 2. The linearizing means 21 of the microcomputer 2 performs polygonal approximation arithmetic according to the kind of the thermocouple TC set by a switch means to obtain data linear to measured temperature. A signal obtained by the linearization 21 and cold contact compensation arithmetic 22 is D/A-converted DA and applied to a transistor (TR) Q through amplifiers A3 and A4. The TR Q controls a current which flows through the two-wire signal line l according to the measured temperature. Respective circuits operate with the lowest current value (<=4mA) of electricity which is supplied from a DC power source BT and into a constant voltage by a power circuit 5 through the signal line l.
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