| 摘要 |
PURPOSE:To perform high-precision measurement by selectively switching plural temperature-measuring resistors and a standard resistor, and thus correcting the contact resistances of switches and connectors, the offset voltage of a lead wire resistance and amplfier, and the output current of a constant current source. CONSTITUTION:A scanner card A is connected to an amplifier card B by selectively switching plural temperature-measuring resistors Rt and a standard resistor Rs. The output of an operational amplifier U2 when the resistor Rt of each channel or the standard resistor Rs is connected to the amplifier card B is stored temporarily in an arithmetic circuit PRC such as a microcomputer, and the influence of the value of the output current of a constant current source Is, the offset voltage and bias current of the amplifier, the contact resistances of connectors C1-C6 and switches S1-SC, lead-wire resistance (r), etc., is eliminated to calculate the value of the resistor Rt. |
