Patent ID: 7360439
Filing Date: 2008-04-22
Classification: G01M,G01R,H05K

Abstract:
1. A sample resistance measurement device characterized by having a sample having a resistance component varied by an environmental condition including external force and a temperature; a fixed reference resistance having a predetermined resistance value of which variation caused by the environmental condition is suppressed; a Wheatstone bridge circuit connecting a first resistance, a second resistance, a third resistance, and a fourth resistance by bridge connection, and is a circuit connecting the first resistance with the fixed reference resistance and the sample in series, wherein resistance values of the second resistance to the fourth resistance are same as the fixed reference resistance; a constant-voltage power supply for applying a constant bridge input voltage between a first connection point connecting the first resistance with the fourth resistance and a third connection point connecting the second resistance and the third resistance of the Wheatstone bridge circuit; a dynamic distortion amplifier circuit for inputting a bridge output voltage from the part between a second connection point connecting the first resistance and the second resistance and a fourth connection point connecting the third resistance and the fourth resistance of the Wheatstone bridge circuit, and outputting a carrier wave signal of a predetermined frequency varied in accordance with the bridge output voltage; and a measured resistance computing unit for detecting the bridge output voltage by sampling a peak level of the carrier wave signal of the dynamic distortion amplifier circuit and calculating resistance of the sample based on the detected bridge output voltage.