Abstract: A control circuit includes: a temperature 30; a temperature sensing section 32; a memory 36, an amplifying section 31 to which the memory and the temperature sensor are electrically connected; a first D/A converting section 38 electrically interposed between the memory and the temperature sensing section; a second D/A converting section electrically interposed between the memory and the amplifying section 31, The amplifying section 31 includes: a polarity inverting circuit 33 connected to the temperature sensor; and a variable attenuator 34, an offset adjusting circuit 100, and an amplifying circuit 35 that are connected sequentially to the polarity inverting circuit. The amplifying section 31 is connected to a sample hold circuit 41 through a displacement buffering means 101. The memory has 8 or less working control voltage setting groups.