| 摘要 |
PURPOSE:To expand the detectable range to the combination of the reflection factor and color of a sheet and mark with a wider range by providing a priority circuit on one side even if the sheet reflection factor and the mark reflection factor are in the preset relationship for the first and second luminescent elements. CONSTITUTION:The relationship between sheet and mark reflection factors is (sheet reflection factor) < (mark reflection factor) for the first luminescent element 1, and (sheet reflection factor) > (mark reflection factor) for the second luminescent element 2, for example. The output of one side, e.g., the first luminescent element 1, has priority via a priority circuit 41 even if the light receiving levels of wavelengths of both luminescent elements 1, 2 in the first and second light receiving regions 11a, 11b are reversed, thus a latch circuit 41 is set or reset by two pulses related to this first luminescent element 1, and the output pulse signal with the width corresponding to the mark width is outputted. The mark detection is thereby allowed even if the relationship between the sheet and mark reflection factors for the two luminescent elements 1, 2 is reversed.
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