| 摘要 |
PURPOSE:To enable the temperature measurement with good accuracy by reducing the error due to the resistance value of wires connecting the temperature measuring resistor, through a given current flowing to the temperature measuring resister constituting the resistance bridge from the constant current source. CONSTITUTION:The apparatus is provided with the resistance bridge including the temperature measuring resistor as one side, power supply circuit 9 which inputs the voltage across the resistance 4 constituting one side of the bridge, in series connection with the temperature measuring resistor 5, and feeds a given current I to the resistor 5, and operational amplifier 6 inputting the output voltage of the bridge. For example, with the circuit shown in figure, the voltage V1 is fed from the power supply circuit 9 so that the voltage across the resistance 4 can be constant. Thus, when the voltage Vi across the resistor 5 is increased by rI, the voltage V1 of the power supply circuit 9 is increased by 2rI, and since the voltage V1 is equally divided at the resistances 2, 3, the common voltage COM is increased by rI. Accordingly, the effect of jumper of the resistor 5 can be eliminated from the voltage between the output terminal of the amplifier 6 and the output terminal to which the common voltage COM is fed. |
