| 摘要 |
PROBLEM TO BE SOLVED: To obtain a method and an apparatus in which a strain is measured by excluding the influence of an initial unbalanced output voltage, by a method wherein the output voltage of a bridge circuit in a state that the strain is not generated in a strain gage is detected in advance as the intial unbalanced output voltage, and the strain of an object is computed by a prescribed expression by using the value of output voltage and by using an output voltage detected in the measurement of the strain. SOLUTION: In a state that a strain gage 1 is not pasted on an object and that it is connected to connecting terminals 21, 22 of a strain measuring apparatus 20, a control unit 24 is operated. A control circuit 35 starts a bridge power-supply circuit 32, and a power-supply voltage V is given via respective input terminals 25, 26. The value of an output voltage (e) generated by a circuit 7 is regarded as an initial unbalanced output voltage e0 so as to be stored and retained in a storage circuit 36. Than, the strain gage 1 is pasted on the object, and value of the output voltage (e) is then stored and retained in the storage circuit 36 in the same manner as a case in which the initial unbalanced output voltage e0 is detected. Strainεis determined by the given expression using the gage factor K, reference resistance value Ro , the sum (r) of resistances ra1 , ra2 and voltage values V, e0 , V3 , (e).
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