| 摘要 |
Strain of an object is measured by a bridge having, in one arm thereof, a strain gage for producing a resistance change depending on the strain developed in the object, and having resistors in the respective remaining three arms thereof. The resistors have respective resistances independent of the strain developed in the object. A pair of power corners are disposed at one pair of diagonally opposite joints, and a pair of signal corners are disposed at another pair of diagonally opposite joints of the strain gage. Strain is measured by detecting an output voltage between the signal corners of the bridge as an initial unbalanced output voltage e0 while no strain is being detecting by the strain gage, applying a power supply voltage between the power corners of the bridge, and detecting an output voltage e between the signal corners to detect strain of the object. Strain developed in the object is measured based on a value epsilon a determined using the detected output voltage e and the initial unbalanced output voltage e0 according to a predetermined relationship between variables e and e0, a voltage value V of the power supply voltage applied between the power corners of the bridge, a gage factor K of the strain gage, and resistances R3 and R4 of the resistors in arms of the bridge which are positioned opposite to the arm holding the strain gage and adjacent to the arm holding the strain gage, respectively.
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