| 摘要 |
PURPOSE:To provide fingerprint input with less noise due to light interference by furnishing a film having light control function, which allows passing of only the light incoming at a certain angle on at least one of the light, which is incoming to the incident surface of a prism, and the lighttaken out of the takeout surface. CONSTITUTION:A beam of light 6 cast down from a light source 2 passes through a vertical beam penetrative highpolymer film 22, and only the beam 16 consisting of component vertical to the cast-down surface 20 of a prism reaches the reflex surface 14 of the prism. The all-reflex conditions are met in a recess 13 of the fingerprint to generate an all-reflex light 17. The light incoming to a protrusion 12 of the fingerprint, on the other hand, misses complete all-reflex-conditions to cause drop of the reflexion ratio, and the light incoming to a water layer 15 also reflects in different directions to become a beam 18 with light quantity and reaches the above-mentioned vertical beam penetrative highpolymer film 22. This light 18 with the direction disturbed will further weaken after passing through the highpolymer film 22, and the light intensity of an all-reflex light can be sensed by a reflex light sensing part without generating interference. |
