| 摘要 |
PURPOSE:To measure lengths of materials to be measured from a short size to a long size quickly with a high precision by attaching plural detectors to a truck extending in the lengthwise direction and moving the truck in accordance with the material to be measured and measuring the extent of movement of the truck. CONSTITUTION:Photoelectric sensors 18 (consisting of light projectors 18a and photodetectors 18b) are attached to a beam 13 of the truck at intervals of an equal length (l). When a material W to be measured is measured, rays of light of the n1-th - the nx-th photoelectric sensors 18 from the right are intercepted by the material W and are not outputted to photodetectors 18b. When the beam 13 is moved for the length (l) in the direction of an arrow Y, the light of the n0-th photoelectric sensor 18 is intercepted and is not outputted, and the nx-th photodetector 18b issues the output. At this time, the extent of movement of the beam of the truck is controlled by a pulse generator 10. If the length from the n0-th photoelectric sensor to the right end of the material W is denoted as (a) and the length from the nx-th photoelectric sensor to the left end of the material W is denoted as (b), a length L of the material is given by L=(lXnx)+(b-a). Consequently, the length is measured quickly because the truck is moved only for a short length. |
