| 摘要 |
PURPOSE:To enable stable use of a detector continuously for a long time with an accurate calibration thereof by a method wherein a passive reflector for calibration is provided to adjust the optical system and then, a simulation signal generation circuit and a comparator circuit are used to adjust the gain of a signal processor. CONSTITUTION:A passive reflector 7 for calibration provided near a pass line of a strip S is scanned with an electronic scan type photoelectric converter 1 while a scan image signal is obtained using a lamp 2. Here, any one or more of the illuminance and the angle of illumination of the lamp 2 and the aperture of the optical system of a converter 1 are adjusted so as to eliminate deviation in the brightness level between this signal and a fixed level of a reference signal uniform in the scanning direction of a camera 1. Then, a simulation signal generation circuit 63 which indicates a specified residual scale state across the width of the strip S and a comparator circuit 65 in which the output of a signal processor 40 normal with respect to a simulation signal is set as reference signal are used to adjust the gain of a unit 40 so that the output signal obtained when the simulation signal is inputted thereinto 40 according to the output of the circuit 65 may coincide with the reference signal corresponding to the simulation signal. |
