| 摘要 |
The present invention realizes accurate determination on marking without using an infrared sensor having high responsiveness and high precision. An infrared sensor is disposed such that a region of a predetermined range on the downstream side in the feed direction of an X-ray film with respect to a scan line, the region including the scan line as a laser beam irradiation position, becomes a detection region. Not only an infrared ray emitted from the laser beam irradiation position but also infrared rays emitted from a plurality of dots formed on the X-ray film irradiated with a laser beam can be also detected by the infrared sensor. Consequently, an output from the infrared sensor is stabilized and by comparing the output with a threshold, occurrence of erroneous printing, poor printing, and the like can be accurately detected.
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