| 摘要 |
Equipment for determining the surface uniformity of film or sheet material, in which the material is arranged to pass over a rotating measuring shaft, a light source being arranged to illuminate the horizon formed by the outer surface of the material exactly where it is in contact with the periphery of the measuring shaft, and also a light detector for detecting light transmitted from the light source and emitting corresponding electric signals to subsequent signal-processing apparatus in order to determine the dimensions, number and locations of the irregularities from the shadows produced by the surface irregularities. In a method for calibrating equipment of this type, at least one calibration shaft (10, 12) is produced with a diameter corresponding to the diameter of the measuring shaft and the thickness of the material being calibrated, after which a number of elevations (No.1, No.2, No.3) are produced on the peripheral surface of the shaft and the actual dimensions of the elevations are determined. The calibration shaft is thereafter rotated in said measuring position and the dimensions of the elevations are determined from transmitted light detected by the light detector. Dimensions thus determined are compared with the actual dimensions of the elevations in order to calibrate the equipment. A device for calibrating such equipment comprises a calibration unit arranged to rotate a calibration shaft provided with elevations of predetermined size on its peripheral surface, in said measuring position, in order to determine the dimensions of the elevations from the light transmission detected and compare them with the actual size of the elevations for calibration of the equipment. |
