Surface treatment for optical image capturing system

• US 6,154,285 A
• Filed: 12/21/1998
• Issued: 11/28/2000
• Est. Priority Date: 12/21/1998
• Status: Expired due to Fees

• Current Assignee: SecuGen Corporation (Pivotec Corp.)
• Original Assignee: SecuGen Corporation (Pivotec Corp.)
• Inventors: Jo, Sung-Chan, Teng, Harry H.
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): STAFIRA, MICHAEL PATRICK
• Application Number:
  US09/217,558
• Time in Patent Office: 708 Days
• Field of Search: 356/445, 356/71, 356/376, 382/108, 382/116, 382/124
• US Class Current: 356/445
• CPC Class Codes: A61B 5/1172 using fingerprinting
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence

Abstract

Disclosed is an image capturing system including a light refractor, a light source, and a light receptor. The light refractor can be a triangular prism and includes an imaging surface against which a fingerprint or other object to be imaged is placed. The imaging surface includes at least a first layer of material which has a first part which includes a polymer and a second part which includes a fluid retained within the polymer. The fluid of the first layer can fill irregularities in the ridges of a fingerprint placed on the imaging surface. This allows a higher contrast, sharper fingerprint image to be captured. The imaging surface can also includes a second layer of protective material interposed between the first layer of material and the surface of the prism to reduce breakdown or deterioration of the first layer of material due to adhesives used on the surface of the prism.

Claims

1. An apparatus for capturing the image of a patterned object comprising:

a transparent light refractor for reflecting and refracting light, the light refractor including at least a first surface, wherein a patterned object may be placed adjacent to the first surface;

a light source adjacent to the light refractor, wherein the light source transmits incident light into the transparent light refractor towards the first surface of the light refractor to generate an image of the patterned object;

a light receptor adjacent to the light refractor for capturing an image of the patterned object placed adjacent to the first surface, wherein at least a portion of the incident light transmitted into the light refractor toward the first surface of the light refractor may be reflected off of the first surface and received by the light receptor;

a first layer of material disposed on the first surface of the light refractor, the first layer of material being substantially transparent and having at least two parts, a first part comprising a polymer and a second part comprising a fluid retained by the polymer, such that the fluid is adapted to fill irregularities in surfaces of a patterned object substantially in contact with the first layer of material; and

a second layer of substantially transparent material interposed between the first layer of material and the first surface of the light refractor.

2. The apparatus of claim 1 wherein the light refractor comprises a triangular prism having three rectangular faces, wherein the first surface is disposed on a rectangular face of the triangular prism, and the light receptor and the light source are each positioned adjacent to a rectangular face of the triangular prism.

3. The apparatus of claim 2 wherein the polymer of the first layer of material comprises polyvinyl chloride and the fluid of the first layer of material comprises at least one plasticizers.

4. The apparatus of claim 3 wherein the at least one plasticizer is selected from the group consisting of dioctyl phtalate (DOP), di(2-ethylhexyl) phtalate (DEHP), and dibutyl phtalate.

5. An apparatus for capturing an image of a patterned object comprising:

a transparent light refractor for reflecting and refracting light, the light refractor including at least a first surface, wherein the patterned object to be imaged may be placed adjacent to the first surface;

a light source adjacent to the light refractor, wherein the light source transmits incident light into the transparent light refractor towards the first surface of the light refractor to generate an image of the patterned object;

a light receptor adjacent to the light refractor for receiving an image of the patterned object to be placed against the first surface, wherein at least a portion of the incident light transmitted through the refractor by the light source may be reflected off of the first surface and received by the light receptor;

a first layer of material provided on the first surface of the light refractor, the first layer of material being transparent and having at least two parts, a first part comprising a polymer and a second part comprising a fluid retained by the polymer, wherein the fluid is adapted to fill irregularities in surfaces of the patterned object that are substantially in contact with the first layer of material; and

a second layer of transparent material interposed between the first layer of material and the first surface of the light refractor.

6. The apparatus of claim 5 wherein:

the second layer is adhered to the first surface of the light refractor, wherein the second layer of material is resistant to deterioration by the acrylic adhesive; and

the first layer is adhered to the second layer of material using a heat bond and the first layer does not come into contact with the acrylic adhesive.

7. The apparatus of claim 6 wherein the second layer of material is selected from the group consisting of polyurethane, polyethylene, poly(ethylene terephthalate), hard coated poly(ethylene terephthalate), poly(ethylene naphthalate), polypropylene, and curable epoxy.

8. The apparatus of claim 7 wherein the patterned object to be imaged is a fingerprint.

9. An apparatus for capturing the image of a patterned object comprising:

a transparent light refractor for reflecting and refracting light, the light refractor including at least a first surface, wherein a patterned object to be imaged may be placed adjacent to the first surface;

a light detector adjacent to a second surface of the light refractor for detecting an image of the patterned object to be placed against the first surface;

a light source adjacent to a third surface of the light refractor which directs light towards the first surface of the light refractor to generate an image of the patterned object;

a first layer of material provided on the first surface of the light refractor, the first layer of material comprising a polymer formed by casting; and

a second layer of substantially transparent material interposed between the first layer of material and the first surface of the light refractor.

10. The apparatus of claim 9 wherein the first layer of material is selected from the group consisting of poly(ethylene terephthalate), hard coated poly(ethylene terephthalate), poly(ethylene naphthalate), polyurethane, polyethylene, polypropylene, curable epoxy, and melamine containing polyacrylic mixtures.

11. The apparatus of claim 9, wherein the first layer comprises a polymer that is substantially transparent and substantially non-pliable.

12. A system for creating an image of a patterned object comprising:

a transparent light refractor for reflecting and refracting light, the light refractor including at least a first surface, wherein a patterned object to be imaged may be placed adjacent to the first surface;

a light source adjacent to the light refractor, wherein the light source transmits incident light into the transparent light refractor towards the first surface of the light refractor to generate an image of the patterned object;

a light receptor adjacent to the light refractor for receiving an image of the patterned object to be placed against the first surface, wherein at least a portion of the incident light transmitted through the refractor by the light source may be reflected off of the first surface and received by the light receptor;

a first layer disposed on the first surface of the light refractor, the first layer comprising a polymer and a fluid retained by the polymer, wherein the fluid is adapted to fill irregularities in the surfaces of the patterned object that are substantially in contact with the first layer of material; and

a second layer interposed between the first layer of material and the first surface of the light refractor.

13. An apparatus for capturing the image of a patterned object comprising:

a transparent light refractor for reflecting and refracting light, the light refractor including at least a first surface adjacent to which a patterned object to be imaged is to be placed;

a light source adjacent to the light refractor that directs light toward the first surface to generate an image of the patterned object, wherein the light source transmits incident light into the transparent light refractor towards the first surface of the light refractor;

a light detector adjacent to the light refractor for detecting an image of the patterned object to be placed against the first surface, wherein at least a portion of the incident light transmitted into the light refractor toward the first surface of the light refractor may be reflected off of the first surface and received by the light detector;

a first layer of material provided on the first surface of the light refractor, the first layer of material being transparent and having at least two parts, a first part which is a polymer and a second part which is a fluid and which is retained by the polymer, such that the fluid can fill irregularities and gaps in a patterned object to be imaged which is placed on the first layer of material; and

a second layer of transparent material interposed between the first layer of material and the first surface of the light refractor.

14. The apparatus of claim 13 wherein:

the second layer of material is adhered to the surface of the light refractor by acrylic adhesive to which the second layer of material is resistant to deterioration; and

the first layer of material is adhered to the second layer of material using a heat bond, such that the first layer of material does not come into contact with the acrylic adhesive.

15. The apparatus of claim 14 wherein the second layer of material is selected from the group consisting of polyurethane, polyethylene, poly(ethylene terephthalate), hard coated poly(ethylene terepthalate), poly(ethylene napthalate), polypropylene, and curable epoxy.

16. The apparatus of claim 15 wherein the patterned object to be imaged is a fingerprint.