| 摘要 |
PURPOSE:To provide an image forming device capable of detecting the use of a non genuine OHP sheet when it is used as a paper sheet and performing warning action for urging the use of a genuine OHP sheet. CONSTITUTION:An OHP sheet 1 provided with a detection mark made transparent by heating is used as the genuine OHP sheet. The image forming device is provided with a heating means 4, optical characteristic measuring means 61 and 62 and a discriminating means 7 for discriminating based on the result of the measurement of the optical characteristic measuring means 61 and 62, the optical characteristic of the detection mark is measured before/after the paper sheet passes through the heating means to discriminate whether or not the paper with the detection mark made transparent is used. Moreover, the optical characteristic of a part except the detection mark is measured to discriminate the OHP sheet 1 from the paper, and the warning action is not performed with respect to a normal sheet, that is, the paper not changed in the optical characteristic before/after the paper passes through the heating means. |
