| 摘要 |
A printed state detecting mark, made up of a printed area and a non-printed area, is printed on an object and illuminated with light. Light, which is reflected from or transmitted through the printed state detecting mark, is detected by a first sensor and a second sensor. A first detected amount of light detected by the first sensor is compared with a predetermined first threshold level to produce a first comparison result, and a second detected amount of light detected by the second sensor is compared with a predetermined second threshold level to produce a second comparison result. A printed state of printed marks on the object is determined based on the first comparison result and the second comparison result.
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