Apparatus for reading fingerprint

• US 6,310,683 B1
• Filed: 08/03/1998
• Issued: 10/30/2001
• Est. Priority Date: 08/05/1997
• Status: Expired due to Fees

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Sasaki, Makoto, Ishii, Hiromitsu, Fujiwara, Minoru, Muto, Tetsuo
• Primary Examiner(s): Evans, F. L.
• Assistant Examiner(s): Smith, Zandra V.
• Application Number:
  US09/128,237
• Time in Patent Office: 1,184 Days
• Field of Search: 356/71, 382/115, 382/116, 382/124, 257/432, 257/436, 250/556
• US Class Current: 356/71
• CPC Class Codes: G06V 40/1318 using electro-optical elements or layers, e.g. electroluminescent sensing

Abstract

A light beam emitted by a surface illuminant reaches the surface of a transparent base layer of a recess/projection detection optical element. A light beam emitted almost vertically is emitted to an air layer. A light beam incident on the transparent base layer at an angle larger than a total reflection angle returns to a two-dimensional photosensor at a portion contacting the air layer, but scatters in a transparent particle at a portion contacting the transparent particle. When a finger is brought into contact with a scattering reflection layer, the scattering reflection state 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. In an area corresponding to a ridge of the fingertip, the light beam scattered by the transparent particle is absorbed. The amount of reflected light beam is small, as indicated by an arrow. An image having bright and dark portions optically emphasized in correspondence with the valley and ridge of the fingertip of the finger can be obtained.

Claims

1. An apparatus for reading a fingerprint comprising:

a light source;

a photosensor having a transparent substrate opposing said light source, said photosensor having a plurality of photosensor portions formed on said substrate and a transparent resin layer covering said photosensor portions; and

a scattering reflection layer formed on said photosensor on a side opposing said light source;

wherein light emitted by said light source and scattered and reflected by said scattering reflection layer is incident on each photosensor portion; and

wherein said scattering reflection layer includes a large number of fine transparent particles.

2. An apparatus according to claim 1, wherein each of said photosensor portions comprises a photoelectric transducer transistor having a first gate electrode having light-shielding properties and located on a light source side and a second gate electrode having light-transmitting properties and located on a scattering reflection layer side.

3. An apparatus according to claim 1, wherein the transparent particles are adhered to said photosensor.

4. An apparatus according to claim 1, wherein the transparent particles are substantially spherical particles each having a diameter of 1 to 30 μ

m.

5. An apparatus according to claim 1, wherein said photosensor portions are arranged at a pitch of 30 to 100 μ

m.

6. An apparatus for reading a fingerprint comprising:

a light source;

a photosensor having a transparent substrate opposing said light source, said photosensor having a plurality of photosensor portions formed on said substrate and a transparent resin layer covering said photosensor portions;

a scattering reflection layer formed on said photosensor on a side opposing said light source; and

an antistatic transparent conductive film formed between said photosensor and said scattering reflection layer;

wherein light emitted by said light source and scattered and reflected by said scattering reflection layer is incident on each photosensor portion.

7. An apparatus according to claim 6, wherein said scattering reflection layer includes a sheet-like member having a plurality of protrusions arranged at a small pitch.

8. An apparatus according to claim 7, wherein each of said protrusions has a columnar shape.

9. An apparatus according to claim 7, wherein each of said protrusions has a substantially hemispherical shape.

10. An apparatus according to claim 7, wherein each of said protrusions has a pyramidal shape.

11. An apparatus according to claim 6, wherein said scattering reflection layer includes a plurality of optical fibers arranged parallel to each other.

12. An apparatus according to claim 11, wherein each of said optical fibers is adhered to said photosensor.

13. An apparatus according to claim 11, wherein said optical fibers are arranged parallel to each other to constitute a plate-like member.

14. An apparatus according to claim 6, wherein each of said photosensor portions comprises a photoelectric transducer transistor having a first gate electrode having light-shielding properties and located on a light source side and a second gate electrode having light-transmitting properties and located on a scattering reflection layer side.

15. An apparatus for reading a fingerprint comprising:

a light source;

a photosensor having a transparent substrate opposing said light source, said photosensor having a plurality of photosensor portions formed on said substrate and a transparent resin layer covering said photosensor portions; and

a scattering reflection layer formed on said photosensor on a side opposing said light source;

wherein light emitted by said light source and scattered and reflected by said scattering reflection layer is incident on each photosensor portion; and

wherein said scattering reflection layer includes a plurality of transparent sheets having different refractive indices.

16. An apparatus for reading a fingerprint comprising:

a light source;

a photosensor having a transparent substrate opposing said light source, said photosensor having a plurality of photosensor portions formed on said substrate and a transparent resin layer covering said photosensor portions;

a scattering reflection layer formed on said photosensor on a side opposing said light source; and

a transparent conductive film for preventing static electricity formed on one surface of said scattering reflection layer;

wherein light emitted by said light source and scattered and reflected by said scattering reflection layer is incident on each photosensor portion.

17. An apparatus according to claim 16, wherein each of said photosensor portions comprises a photoelectric transducer transistor having a first gate electrode having light-shielding properties and located on a light source side and a second gate electrode having light-transmitting properties and located on a scattering reflection layer side.

18. An apparatus according to claim 16, wherein said scattering reflection layer includes a sheet-like member having a plurality of protrusions arranged at a small pitch.

19. An apparatus according to claim 16, wherein said scattering reflection layer includes a plurality of optical fibers arranged parallel to each other.

20. An apparatus according to claim 18, wherein each of said protrusions has a columnar shape.

21. An apparatus according to claim 18, wherein each of said protrusions has a substantially hemispherical shape.

22. An apparatus according to claim 18, wherein each of said protrusions has a pyramidal shape.

23. An apparatus according to claim 19, wherein each of said optical fibers is adhered to said photosensor.

24. An apparatus according to claim 19, wherein said optical fibers are arranged parallel to each other to constitute a plate-like member.

25. An apparatus for reading a fingerprint comprising:

a light source;

a photosensor arranged on said light source and having a large number of photosensor portions; and

a large number of transparent particles attached to said photosensor and spaced apart from each other.

26. An apparatus for reading a fingerprint comprising:

a light source;

a photosensor arranged on said light source and having a large number of photosensor portions; and

a scattering reflection layer including a transparent base layer mounted on the photosensor and having a plurality of hollow portions in which at least one of a gas and a liquid is filled.

27. An apparatus for reading a fingerprint comprising:

a light source;

a photosensor arranged on said light source and having a large number of photosensor portions;

a scattering reflection layer formed on said photosensor; and

a transparent conductive film for preventing static electricity formed on said scattering reflection layer,

wherein light emitted by said light source and scattered and reflected by said scattering reflection layer is incident on each photosensor portion.

28. An apparatus according to claim 27, wherein said transparent conductive film is formed between said photosensor and said scattering reflection layer.

29. An apparatus for reading a fingerprint comprising:

a light source;

a photosensor arranged on or over said light source, said photosensor comprising a plurality of photosensor portions each of which includes a semiconductor layer, source and drain electrodes, and a gate electrode, wherein each of said photosensor portions outputs a drain current in accordance with an amount of incident light to said semiconductor layer thereof;

a recess/projection detection optical element layer disposed on said photosensor, said recess/projection detection optical element having an upper surface to be contacted with a finger thereon and a lower surface opposing said upper surface; and

a transparent conductive film for preventing static electricity formed on one of said upper and lower surfaces of said recess/projection detection optical element layer.

30. An apparatus for reading a fingerprint comprising:

a light source;

a photosensor arranged on or over said light source, said photosensor comprising a plurality of photosensor portions each of which includes a semiconductor layer, source and drain electrodes, and a transparent gate electrode, wherein an overcoat film is deposited on an entire surface of said photosensor portions, and wherein each of said photosensor portions outputs a drain current in accordance with an amount of incident light to said semiconductor layer thereof; and

a transparent conductive film for preventing static electricity formed on said overcoat film of said photosensor.