| 摘要 |
PROBLEM TO BE SOLVED: To comprehensively detect failure relating to paper conveyance, prevent information for detecting failure unnecessary for a user from remaining on a paper surface in a visible state, and automatically detect a print position by a printer. SOLUTION: An invisible mark 50 for detecting abnormality relating to the paper conveyance is previously printed on a paper 12 by using transparent ink, which is transparent in visible light and is visually discolored by specific wavelength light except for visible light. A transparent ink reading part 30A is arranged on a halfway of a conveying path 18 of the printer 10, and the invisible mark 50 is visually discolored and is read by irradiating the specific wavelength light except for the visible light on the conveyed paper 12 by the transparent ink reading part 30A. It is determined whether abnormality occurs in a conveying state of the paper 12 by an operation processing part 30B by using a read result by the transparent ink reading part 30A. |
