Patent Number: 6,310,683

Title: Apparatus for reading fingerprint

Abstract: A light beam emitted by a surface illuminant reaches the surface of atransparent base layer of a recess/projection detection optical element. Alight beam emitted almost vertically is emitted to an air layer. A lightbeam incident on the transparent base layer at an angle larger than atotal reflection angle returns to a two-dimensional photosensor at aportion contacting the air layer, but scatters in a transparent particleat a portion contacting the transparent particle. When a finger is broughtinto contact with a scattering reflection layer, the scattering reflectionstate does not change in an area corresponding to a valley of a fingertip.As indicated by an arrow, an amount of reflected light beam is large. Inan area corresponding to a ridge of the fingertip, the light beamscattered by the transparent particle is absorbed. The amount of reflectedlight beam is small, as indicated by an arrow. An image having bright anddark portions optically emphasized in correspondence with the valley andridge of the fingertip of the finger can be obtained.

Inventors: Fujiwara; Minoru (Tokyo, JP), Sasaki; Makoto (Hachioji, JP), Ishii; Hiromitsu (Hamura, JP), Muto; Tetsuo (Hachioji, JP)


International Classification:

Expiration Date: 10/32013