MULTI-CHANNEL STRAIN MEASURING CIRCUIT

PROBLEM TO BE SOLVED: To use in common a bridge constitutional resistance in all channels, and to use a switching element of a high ON-state resistance value of a semiconductor relay or the like as a switching element in a bridge. SOLUTION: In the case of one gage method, a constant current is sent in a route: an amplifier AMP2→a switch element Sa for selective scanning→a connection terminal Ta→a strain gage Ga→a connection terminal Tc→a switch element Sc'→a switch element SW2→a resistance Rb. A potential of the connection terminal Ta to which one end of the strain gage Ga is connected is extracted by an amplifier AMP4, and an error voltage portion in the ON-state resistance of the switch element Sc' and the switch element SW2 is extracted by an amplifier AMP5. A series circuit of the bridge constitutional resistances Rd, Rc is inserted between output terminals of the amplifiers AMP4, AMP5, and the output potential on one side is acquired from a connection point between resistances Rd, Rc. The output potential on the other side is acquired from a connection terminal Tb connected to the other end of the strain gage Ga. The voltage between the output potentials is extracted by a differential amplifier AMP1. COPYRIGHT: (C)2005,JPO&NCIPI