Patent ID: 8689569

Claim:
A cooling control circuit for a Peltier element, the cooling control circuit comprising: a current detection resistor used to detect current flowing to the Peltier element and including a first terminal, which is connected to the Peltier element, and a second terminal; a first amplification circuit including: a first operational amplifier having a non-inverting input terminal, which is connected to the first terminal of the current detection resistor, an inverting input terminal, and an output terminal; a first resistor including a thermistor and connected between the inverting input terminal of the first operational amplifier and the output terminal of the first amplifier; and a second resistor connected between the second terminal of the current detection resistor and the inverting input terminal of the first operational amplifier; a second amplification circuit including: a second operational amplifier having a non-inverting input terminal, which is connected to the first terminal of the current detection resistor, an inverting input terminal, and an output terminal; a third resistor connected between the inverting input terminal of the second operational amplifier and the output terminal of the second amplifier; and a fourth resistor connected between the second terminal of the current detection resistor and the inverting input terminal of the second operational amplifier; and a current control circuit that receives output voltage of the second amplification circuit when the ambient temperature is greater than or equal to a predetermined temperature and controls the current flowing to the Peltier element so as to be constant based on the output voltage of the second amplification circuit, and receives output voltage of the first amplification circuit that is in accordance with the temperature characteristics of the thermistor when the ambient temperature is less than the predetermined temperature and controls the current flowing to the Peltier element based on the output voltage of the first amplification circuit.