| 摘要 |
PURPOSE:To enable the yellow portion of a color ink ribbon or the like to be easily detected by using a light emitting element with an emission wavelength selected in the neighborhood of values 560-580nm and receiving the light emitted from the element and transmitted through the yellow portion. CONSTITUTION:A sensor 8 is formed in a casing 81 with a groove 82 through which a color ink ribbon passes. A light emitting element 83 and a photosensitive element 84 are housed both in the manner to oppose the groove 82. A light emitting diode with a peak emission wavelength selected in the neighborhood of values 560-580nm is used as the element 83 and a general photodiode is used as the element 84. The color ink ribbon has spectral characteristics that, when the emission wavelength is selected in the neighborhood of values 560-580nm, the light from the element 83 is transmitted only through yellow and not through cyan, magenta and black. Accordingly, the element 84 can detect the light transmitted only through the yellow.
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