Apparatus for reducing ambient light into an optical print scanner
View Patent ↗A light shroud reduces or eliminates the effects of ambient light on an optical fingerprint scanner. Because of the geometry of a prism used in the scanner, ambient light from only certain incidence angles can interfere with an image produced by the scanner. The light shroud blocks this ambient light entering the system at angles which allow the light to interfere with the illumination system or camera. In an embodiment, the light shroud can be closed to act as a cover, protecting the platen surface.
1. An optical print scanning system, comprising:
a live print scanner having a platen for receiving an object having a print pattern, wherein the platen is the surface of a prism; and
a light shroud,
wherein the light shroud allows access to the live print scanner by a user while blocking ambient light from entering the live print scanner at angles which may adversely interfere with an image produced by the live print scanner.
2. The optical print scanning system of claim 1 , wherein the live print scanner comprises:
an illumination system for illuminating the platen;
an optical system for conditioning and focusing light reflected from the platen; and
a camera for imaging the light reflected from the platen.
3. The optical print scanning system of claim 2 , wherein the illumination system comprises:
a light source; and
a light wedge, wherein the light wedge directs light from the light source to the platen.
4. The optical print scanning system of claim 2 , wherein the light shroud blocks ambient light incident from a camera-side direction at incidence angles in the range of about 0 to 84.3 degrees.
5. The optical print scanning system of claim 4 , wherein the light shroud blocks ambient light incident from an illumination-side direction at incidence angles in the range of about 15 to 84.3 degrees.
6. The optical print scanning system of claim 1 , wherein the light shroud has an open and closed position, such that the light shroud blocks the ambient light when in the open position and protects the live print scanner when in the closed position.
7. An optical fingerprint system, comprising:
a platen that receives a fingerprint, wherein the platen is a surface of a prism;
an illumination system that illuminates the platen;
a camera that images the fingerprint; and
a light shroud, wherein the light shroud allows access to the platen while blocking ambient light from entering at all angles which may adversely interfere with the illumination system or the camera.
8. The fingerprint system of claim 7 , wherein the angles range from about 0 to 84.3 degrees.
9. The fingerprint system of claim 8 , wherein the angles range from about 15 to 84.3 degrees.
10. The fingerprint system of claim 7 , wherein the light shroud has an open and closed position, such that the light shroud blocks said ambient light when in the open position, and the light shroud protects the platen when in the closed position.
11. The fingerprint system of claim 7 , wherein the light shroud is curved.
12. The fingerprint system of claim 7 , wherein the light shroud is angled.
13. The fingerprint system of claim 7 , wherein the illumination system comprises a diffuser.
14. A cover for an optical scanning system, comprising:
a light-blocking shield in close proximity to a platen of the optical scanning system, wherein the platen is a surface of a prism,
wherein the light-blocking shield has an open position in which the light-blocking shield blocks ambient light from entering the platen from angles that adversely interfere with the optical scanning system when in the open position, and
wherein the light-blocking shield has a closed position in which the light-blocking shield fully covers the platen.
15. The cover of claim 14 , wherein the light-blocking shield blocks ambient light from entering the platen at angles less than about 84.3 degrees.
16. The cover of claim 15 , wherein the light blocking-shield blocks ambient light from entering the platen at angles between about 15 and 84.3 degrees.
17. The cover of claim 14 , wherein the light-blocking shield blocks ambient light from entering the platen from a camera-side direction.
18. The cover of claim 17 , wherein the light-blocking shield blocks ambient light from entering the platen from a camera-side direction at angles between about 15 and 84.3 degrees.
19. The cover of claim 14 , wherein the light-blocking shield is curved.
20. The cover of claim 14 , wherein the light-blocking shield is angled.
21. The cover of claim 14 , wherein the light-blocking shield is straight.