| 摘要 |
PROBLEM TO BE SOLVED: To provide a digital hollow displacement gauge which can measure a site that is conventionally difficult to be measured, with relative ease.SOLUTION: The digital hollow displacement gauge that measures the length of an inner space such as tunnel, or the like, includes a comparatively compact main unit 2, a further compact sensor unit 4 connected to the main unit, and a digital display 6 for indicating measuring data from the sensor unit, and a rotary shaft 17 having a comparatively large diameter section 17w and a comparatively small diameter section 17n and a plurality of tension generators 19-1 to 19-4 for producing a plurality of constant tensile tensions are provided inside the main unit. A magnetic tape 8 wherein an N pole and an S pole are mutually magnetized at a specified period is wound around the large-diameter section of the rotary shaft, and a band-like spring from the respective tension generator is wound around the small-diameter section of the rotary shaft. When the length is measured, a fixed tensile torque from the plurality of tension generators is imparted to the comparatively small diameter section of the rotary shaft, so that the magnetic tape is pulled at a fixed tension. |
