| 摘要 |
PURPOSE:To realize a compact input device for fingerprint image data and to obtain a fingerprint image free from distortion, by using a glass plate having a ground finger touch surface and a photodetector which receives light from the finger touch surface on the side opposite to the finger touch surface of said glass plate. CONSTITUTION:A 2-dimensional image sensor 15 contains a flat glass plate having a ground finger touch surface 12 and a photodetector, e.g., a charge coupled device CCD which is set on the side opposite to the surface 12 and receives the beams from a light source 14 which radiates the light on the surface 12 of the plate 11 and from the surface 12. Then the sensor 15 images the light reflected from the surface 12 on the photodetecting surface of the sensor 15 and applies photoelectric conversion to this image for acquisition of the picture element data. In such a way, the total reflection of the light is not utilized and therefore a mirror, etc. can be omitted. Furthermore, the photodetector is set so that a fingerprint image is viewed approximately straight and therefore the image distortion is decreased. |
