Pattern detection system

• US 7,969,422 B2
• Filed: 07/15/2005
• Issued: 06/28/2011
• Est. Priority Date: 07/15/2005
• Status: Active Grant

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Gruhlke, Russell W.
• Primary Examiner(s): Nguyen; Kevin M
• Assistant Examiner(s): Lee, Jr.; Kenneth B
• Application Number:
  US11/182,306
• Publication Number:
  US 20070013679A1
• Time in Patent Office: 2,174 Days
• Field of Search: 345173-179, 178 1801- 1811, 178 1901- 1907, 200/512, 340/407.1
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/0338 Fingerprint track pad, i.e. fingerprint sensor used as pointing device tracking the fingertip image
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/042 by opto-electronic means

Abstract

A detection system. The detection system includes a transparent substrate, an image sensor array, and a reflective layer. The substrate has first surface located opposite second surface and third surface located opposite fourth surface. The array is adjacent to the fourth surface. The reflective layer is adjacent to the third surface; the substrate is configured to receive light through the first surface; the second surface is configured to reflect the received light onto the third surface at a pre-selected angle of incidence; the reflective layer is configured such that the light creates surface plasmons whenever a first dielectric having a first refractive index is adjacent to the reflective layer; the reflective layer is configured to reflect the light onto the array whenever a second dielectric having a second refractive index is adjacent to the reflective layer; and the first refractive index differs from the second refractive index.

Claims

1. A detection system, comprising:

a substrate having a first side surface located opposite a second side surface and an upper surface located opposite a lower surface, wherein the substrate is transparent,

an image sensor array adjacent to the lower surface, wherein the array comprises multiple photosensitive elements; and

a reflective layer over the upper surface, wherein the substrate is configured to receive light through the first side surface, wherein the light has a pre-selected wavelength, wherein the second side surface is configured to reflect the received light onto the upper surface at a pre-selected angle of incidence, wherein the second side surface is angled to be non-perpendicular with respect to the upper surface to reflect the received light onto the upper surface, wherein the reflective layer is configured such that the light creates surface plasmons whenever a first dielectric having a first refractive index is adjacent to the outer surface of the reflective layer, wherein the surface plasmons produce a pattern that is imaged by the image sensor array for detection, wherein the reflective layer is configured to reflect the light onto the image sensor array whenever a second dielectric having a second refractive index is adjacent to the outer surface of the reflective layer, and wherein the first refractive index differs from the second refractive index.

2. The detection system as recited in claim 1, further comprising:

a light source, wherein the light source is configured to emit the light.

3. The detection system as recited in claim 2, wherein the light source is a laser.

4. The detection system as recited in claim 2, further comprising:

a lens, wherein the lens is configured to collimate the light onto the first side surface.

5. The detection system as recited in claim 2, further comprising:

a polarizer located between the light source and the first side surface.

6. The detection system as recited in claim 1, wherein the second side surface is configured for total internal reflection of the light.

7. The detection system as recited in claim 1, wherein the second side surface is a mirrored surface.

8. The detection system as recited in claim 1, wherein the first dielectric comprises at least one ridge of a finger.

9. The detection system as recited in claim 1, wherein the first dielectric is selected from the group consisting of finger tissue and air.

10. The detection system as recited in claim 1, wherein the second dielectric is selected from the group consisting of finger tissue and air.

11. The detection system as recited in claim 1, wherein the reflective layer is positioned on the upper surface such that at least some of the upper surface is covered by the reflective layer, and wherein the reflective layer is made of metal or conductor.

12. A detection system, comprising:

a substrate having a first side surface located opposite a second side surface and an upper surface located opposite a lower surface, wherein the substrate is transparent,

an image sensor array adjacent to the lower surface, wherein the array comprises multiple photosensitive elements; and

a reflective layer over the upper surface; and

a protective layer over the reflective layer, wherein the reflective layer is interposed between the upper surface and the protective layer, wherein the substrate is configured to receive light through the first side surface, wherein the light has a pre-selected wavelength, wherein the second side surface is configured to reflect the received light onto the upper surface at a pre-selected angle of incidence, wherein the second side surface is angled to be non-perpendicular with respect to the upper surface to reflect the received light onto the upper surface, wherein the reflective layer is configured such that the light creates surface plasmons whenever a first dielectric having a first refractive index is adjacent to the surface of the protective layer located opposite the outer surface of the reflective layer, wherein the surface plasmons produce a pattern that is imaged by the image sensor array for detection, wherein the reflective layer is configured to reflect the light onto the image sensor array whenever a second dielectric having a second refractive index is adjacent to the surface of the protective layer located opposite the outer surface of the reflective layer, and wherein the first refractive index differs from the second refractive index.

13. The detection system as recited in claim 12, further comprising:

a light source, wherein the light source is configured to emit the light.

14. The detection system as recited in claim 13, wherein the light source is a laser.

15. The detection system as recited in claim 13, further comprising:

a lens, wherein the lens is configured to collimate the light onto the first side surface.

16. The detection system as recited in claim 13, further comprising:

a polarizer located between the light source and the first side surface.

17. The detection system as recited in claim 12, wherein the second side surface is configured for total internal reflection of the light.

18. The detection system as recited in claim 12, wherein the second side surface is a mirrored surface.

19. The detection system as recited in claim 12, wherein the first dielectric comprises at least one ridge of a finger.

20. The detection system as recited in claim 12, wherein the first dielectric is selected from the group consisting of finger tissue and air.

21. The detection system as recited in claim 12, wherein the second dielectric is selected from the group consisting of finger tissue and air.

22. The detection system as recited in claim 12, wherein the reflective layer the reflective layer is positioned on the upper surface such that at least some of the upper surface is covered by the reflective layer, and wherein the reflective layer is made of metal or conductor.