| 摘要 |
PURPOSE:To make possible compensation of non-linearity in the relations between duty factors and the arrive temperature of a thermoelectric element by making the relations of the duty factors of the pulse train driving the thermoelectric element having Peltier effect and control DC voltage non-linear. CONSTITUTION:The temperature of a thermoelectric element 1 is converted to an electric signal by a detecting element 2 and this signal is applied to a differential type DC amplifier 3. The DC voltage from a DC power source 5 via potentiometer 4 is also applied to the amplifier 3, by whith the temperature of the element 1 is set. The output voltage of the amplifier 3 determines the slice level of a compara tor 6. Hence, the output of a saw tooth wave generating circuit 7 is subjected to waveform shaping 8 and the waveform signal in which the leading edge is linear and the first portion of the trailing edge becomes a sublinear curve is obtained as square pulse train from the comparator 6. The pulse width thereof is changed by the slice level, by which the duty factor of the output pulse train is determined and the control signal of a large power switching circuit 9 driving the element 1 is created, thus the compensation at the small set value may be obtained. |
