| 摘要 |
PURPOSE:To improve an S-N ratio by constituting an image pickup means so as to receive light irregularly reflected by the finger print pattern of a finger coming into contact with a prescribed position. CONSTITUTION:When a finger 41 is pressed to a finger print sampling part 40a on the upper surface of a conductive plate 40, the irregular reflection of light is generated on the part where the finger comes into contact with the upper surface of the conductive plate 30 in accordance with the rugged surface of the finger print pattern. Thereby, light L3 having an angle less than the critical angle of total reflection is projected from the lower face of the plate 40 to the outside and impressed to an image pickup device 43. The device 43 concentrates the light L3 as an image and converts the image into an electric signal to obtain an electric signal indicating the finger print pattern. |
