| 摘要 |
PURPOSE:To change a reference value to a proper value according to the conditional change with the lapse of time by resetting the reference value to discriminate between galvanized sheet iron and common steel sheet for each time of performing predetermined number of discrimination. CONSTITUTION:A measured value group including a measured value of reflected light of the steel sheet is stored and a value not included in the limits of an error expected based on the stored measured value group is set as the reference value by a reference value setting means. Then, the discrimination between the galvanized sheet iron and the common steel sheet is performed by the result whether the measured value of the reflected light on the surface of the sheet iron to be discriminated is smaller or larger than the set reference value by a discriminating means. The reference value is changed to the proper value by resetting the new reference value based on the renewed measured value group by the reference value setting means for each time of performing predetermined number of discrimination. Thus, the accurate discrimination can be performed in using extending the long period. |
