| 摘要 |
PURPOSE:To improve the accuracy with a simple construction by reducing the effect of temperature variation with a one-chip type composite resistance employed for the dummy resistance of a bridge for converting changes in the resistance of strain gauges into an electrical signal. CONSTITUTION:Strain gauges 12a and 12b are connected to two arms of a bridge circuit D of a strain gauge for detecting a load while dummy resistances R3 and R4 to other two arms thereof. One chip type thick film composite resistances are used for the dummy resistances R3 and R4 to hold the temperature coefficient within about + or -5ppm/ deg.C. Strain gauges 12a and 12b cause changes in the resistance according to the load and a coresponding deviated voltage of the bridge circuit D is converted into a DC signal with a phase discriminator F via an amplifier E. The signal is applied to an arithemetic processing circuit H via an A/D converter G to calculate the weight value, which is indicated on a display element J through a display circuit I. This reduces errors due temperature variation thereby enabling a highly accurate measurement of the load with a simple construction. |
