| 摘要 |
A color image sensor sequentially acquires a plurality of fingerprint images when a finger is pressed against the detector surface. A color information extraction unit detects the finger color in synchronization with the input of the plurality of fingerprint images. An areal information extraction unit detects a physical quantity representing the pressure applied by the finger to the color image sensor when the plurality of fingerprint images are acquired, particularly, the quantity related with the area of the finger in contact with the detector surface. A living body identification unit determines whether the finger is a live or dead one by the analysis of correlation between the physical quantity and the finger color. According to this configuration, even if the finger color does not change much, it is possible to distinguish living bodies from dead ones if there is a sufficient correlation with information such as the area of the fingerprint that reflects the finger pressure. The thickness of the fingerprint input unit is approximately 1-2 mm, determined by the sum of the thickness of the planar light source and that of the color image sensor.
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