| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and a device for distinguishing a coin capable of obtaining a stable image signal by periodically obtaining image signals of plural test patterns arranged in a coin passing position and its periphery and thereby monitoring the optical aging effect due to contamination or the like. SOLUTION: The test patterns disposed on a coin passage wall 102 are irradiated with light from a light source part 104 at predetermined intervals while the coin C is not put into a coin passage 101 to obtain the images of the test patterns by an area sensor 105, the similarities of the obtained image signals of the test patterns are respectively calculated by a test pattern image feature abstracting part 110, a test pattern image determining part 111 determines them to be normal when the minimum value of the similarities is larger than a threshold value and to be abnormal when it is smaller, and determines them to be normal when the difference between the maximum value and the minimum value of the similarities is smaller than a threshold value and to be abnormal when it is larger, and when they are determined to be abnormal, a warning informing part 112 informs the outside of a warning.
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