| 摘要 |
PROBLEM TO BE SOLVED: To measure moving amount of a paper-like object real time by calculating frequency peak interval of frequency spectrum extracted by an extracting means. SOLUTION: A light irradiation means 20 emits a coherent light 21 on either a front or a rear surface of a bill 2, and an optical system 23 condenses a reflection light 22 for it to be imaged at a position of focal length f, and an imaging device 24 is provided at the imaging position. In the first memory 25, the output of a device 24 at a time point Tαk is stored, and in the second memory 26, the output of the device 24 at a time point Tα+βis stored. (αandβare time variables set by a processing program) Then, an extracting part 27a of a picture processing part 27 takes in a stored image in the memory 26, and extracts a frequency spectrum out of the picture, and a detecting part 27b detects a frequency peak of the frequency spectrum, and then, a calculation part 27c calculates a moving amount based on the interval of adjoining frequency peaks.
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