| 摘要 |
PROBLEM TO BE SOLVED: To provide a fluorescent thread detector of paper sheets capable of detecting a fluorescent thread simply and surely. SOLUTION: The fluorescent thread detector of paper sheets 10 irradiates the fluorescent threads S provided at a paper money 2 with ultraviolet rays by an ultraviolet LED 12 to detect the fluorescence emitted from the thread S by a photo sensor 16. In front of the sensor 16 within a casing 11, an infrared cut filter 17 and a condenser 18 with a long wavelength transmission filter function are provided. In cooperation with these filter 17 and the condenser 18, a fluorescent transmission wavelength band including only the fluorescent wavelength peak of the red fluorescent thread of the smallest fluorescent quantity among respective fluorescent wavelength peaks of red, yellow green and blue fluorescent thread being the object of detection is formed.
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