| 摘要 |
<p>PURPOSE:To eliminate an influence on the design of an object and to improve the degree of freedom of the design by providing a polarizing filter on the photodetection surface of a photodetecting means transmitting only linear polarized light which is not rotated. CONSTITUTION:Light, which is transmitted through a light reflecting layer 10, of laser light which is made incident on a discrimination seal 3 passes through a polarization plane rotating layer 12 and is reflected by the surface 1a of a card 1 and passes through the polarization plane rotating surface 12 again, so that its plane of polarization is rotated by 90 deg.. In the case where the card 1 is actually discriminated, the card 1 is conveyed and when the discrimination seal 3 is confronted with the light emitting element 6 of a light projection and photodetection unit 5, the light emitting element 6 irradiates the discrimination seal 3 with illumination light of 780nm consisting of linear polarized light in a specific direction. Then, the light which is diffracted and reflected by the discrimination seal 3 is transmitted through a polarizing filter 7 and photodetected by any of respective parts of the light receiving element 8 to discriminate whether the card 1 is a regular card or not according to the photodetection intensity.</p> |
