ZERO POINT VARIATION DETECTION DEVICE AND ZERO POINT VARIATION CORRECTION DEVICE FOR LOAD CELL

摘要

PURPOSE: To detect and correct the variation of zero point with temperature variation caused by the shift of attached position of strain gauges on a load cell. ;CONSTITUTION: For a load cell connecting in series a temperature sensing element R_c between a bridge circuit 8 having strain gauges G₁ to G₄ placed on a strain body and two driven power source E/2, the voltage of node (b) of the bridge circuit 8 is supplied to a CPU16 through change-over switches 10, 14, a differential amplification circuit 12, a filter circuit 18 and an A/D converter circuit 20, and judges whether the absolute value of both voltage are equal. If they are equal, it is judged that no temperature variation is present for the zero point, and if they are not equal, it is judged that a temperature variation is present for the zero point. When CPU 16 judged there was temperature variation of the zero point, it calculates the addition value of the voltage at the nodes (b) and (d) as the zero point variation and corrects the output voltage of the load cell as the difference of the voltage between (b) and (d) with the above zero point variation.;COPYRIGHT: (C)1995,JPO