CONTROL OF LIQUID TEMPERATURE

摘要

PURPOSE:To maintain desired temperature quickly even against any sharp change in the temperature by controlling the energization of a heater with the output of an integral control circuit following a proportional control circuit and a differentiation control circuit to which outputs are fed from a sensor for detecting the temperature of a liquid. CONSTITUTION:Outputs of an auxiliary temperature sensor 22 mounted on a thermostat frame are fed to a Peltier element controlling circuit 31 and according to outputs thereof, the output voltage of a power source 32 connected to the Peltier element 15 is controlled so that the frame 13 always attains a specified temperature 6. A temperature sensor 20 provided on the frame 13 is connected to one side of a d.c. bridge 33 to feed output signals thereof to a proportional control circuit 34, which controls the heating level from a heater 18 in proportion to a deviation between the set temperature and a flow cell temperature. Output signals are fed to a differentiation circuit 35 from the circuit 34, which controls the heating level by the heater 18 according to the rate of any sharp change in the flow cell temperature. The outputs of the circuit 35 is also fed to an integral control circuit 36 to remove the offset. The output thereof is fed to a heater driving circuit 37.