Optical sensor for integration over a display backplane

• US 10,169,630 B2
• Filed: 03/31/2016
• Issued: 01/01/2019
• Est. Priority Date: 12/03/2015
• Status: Active Grant

• Current Assignee: Fingerprint Cards IP AB
• Original Assignee: Synaptics Incorporated
• Inventors: Fomani, Arash Akhavan, Smith, Patrick, Mienko, Marek, Wickboldt, Paul
• Primary Examiner(s): Tucker, Wesley J
• Application Number:
  US15/087,971
• Publication Number:
  US 20170161544A1
• Time in Patent Office: 1,006 Days
• CPC Class Codes: G01J 1/0214 Constructional arrangements for removing stray light
• CPC Class Codes: G01J 1/0233 Handheld
• CPC Class Codes: G01J 1/04 Optical or mechanical part supplementary adjustable parts
• CPC Class Codes: G01J 1/0407 Optical elements not provided otherwise, e.g. manifolds, windows, holograms, gratings
• CPC Class Codes: G01J 1/0411 using focussing or collimating elements, i.e. lenses or mirrors; Aberration correction
• CPC Class Codes: G01J 1/0414 using plane or convex mirrors, parallel phase plates, or plane beam-splitters
• CPC Class Codes: G01J 1/0422 using light concentrators, collectors or condensers
• CPC Class Codes: G01J 1/0429 using polarisation elements
• CPC Class Codes: G01J 1/0437 using masks, aperture plates, spatial light modulators, spatial filters, e.g. reflective filters
• CPC Class Codes: G01J 1/0488 with spectral filtering
• CPC Class Codes: G01J 1/0492 using at least two different filters
• CPC Class Codes: G01J 1/06 Restricting the angle of incident light
• CPC Class Codes: G01J 1/08 Arrangements of light sources specially adapted for photometry standard sources, also using luminescent or radioactive material
• CPC Class Codes: G02F 1/13318 Circuits comprising a photodetector
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/133512 Light shielding layers, e.g. black matrix G02F1/136209 takes precedence
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/1368 in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: G06F 3/0428 : by sensing at the edges of the touch surface the interruption of optical paths, e.g. an illumination plane, parallel to the touch surface which may be virtual sensing beam interruptions in a planar beam grid of an optical touch-screen G06F3/0421
• CPC Class Codes: G06V 40/1318 : using electro-optical elements or layers, e.g. electroluminescent sensing
• CPC Class Codes: G06V 40/1341 : Sensing with light passing through the finger
• CPC Class Codes: G06V 40/1359 : Extracting features related to ridge properties; Determining the fingerprint type, e.g. whorl or loop

Abstract

Systems and methods for optical imaging are disclosed. An optical sensor for imaging a biometric input object on a sensing region includes a transparent layer having a first side and a second side opposite the first side; a set of apertures disposed above the first side of the transparent layer; a first set of reflective surfaces disposed below the second side of the transparent layer configured to receive light transmitted through the first set of apertures and to reflect the received light; a second set of reflective surfaces disposed above the first side of the transparent layer configured to receive the light reflected from the first set of reflective surfaces and to further reflect the light; and a plurality of detector elements positioned to receive the further reflected light from the second set of reflective surfaces.

Claims

1. An optical sensor for imaging a biometric input object on a sensing region, comprising:

a transparent layer having a first side and a second side opposite the first side;

a set of apertures disposed above the first side of the transparent layer;

a first set of reflective surfaces disposed below the second side of the transparent layer configured to receive light transmitted through the set of apertures and to reflect the received light;

a second set of reflective surfaces disposed above the first side of the transparent layer configured to receive the light reflected from the first set of reflective surfaces and to further reflect the light; and

a plurality of detector elements positioned to receive the further reflected light from the second set of reflective surfaces.

2. The optical sensor of claim 1, wherein the detector elements have a top side facing the sensing region and an underside opposite to the sensing region, wherein the detector elements are configured to receive the further reflected light from the top side facing the sensing region.

3. The optical sensor of claim 1, wherein the set of apertures are defined by openings in a light blocking layer.

4. The optical sensor of claim 3, wherein the blocking layer comprises a light absorbing material.

5. The optical sensor of claim 3, wherein the light blocking layer includes first portions above and parallel to a plane of the detector elements and second portions in an area that at least partially surrounds the detector elements.

6. The optical sensor of claim 5, wherein the second portions are in a plane substantially perpendicular to the plane of the detector elements.

7. The optical sensor of claim 1, wherein the first set of reflective surfaces comprise mirrored surfaces, each of the mirrored surfaces being surrounded by a light absorbing material.

8. The optical sensor of claim 7, wherein the mirrored surfaces are recessed relative to the light absorbing material.

9. The optical sensor of claim 1, wherein the optical sensor is integrated with a display and one or more display pixels of the display form a light source configured to provide the light received by the detector elements.

10. The optical sensor of claim 1, further comprising:

a liquid crystal display (LCD) backlight which forms a light source configured to provide the light received by the detector elements.

11. The optical sensor of claim 1, wherein at least two of the following widths are adjusted to limit an acceptance angle of light for the detector elements:

(a) a width of the apertures in the set of apertures, (b) a width of the reflective surfaces in the first set of reflective surfaces, (c) a width of the reflective surfaces in the second set of reflective surfaces, and (d) a width of surfaces of the detector elements positioned to receive the further reflected light.

12. A display including a sensor for imaging a biometric input object, comprising:

a set of display pixels;

a first light blocking layer having a set of apertures and a first set of mirrors;

a transparent layer positioned below the first light blocking layer;

a reflective layer positioned below the transparent layer configured to receive light transmitted through the set of apertures and to reflect the received light towards the first set of mirrors, the first set of mirrors being configured to further reflect the reflected light from the reflective layer; and

a set of detector elements positioned below the transparent layer and configured to detect the further reflected light from the first set of mirrors.

13. The display of claim 12, wherein the detector elements are thin film photodetectors.

14. The display of claim 12, wherein at least two of the following widths are adjusted to limit an acceptance angle of light for the detector elements:

(a) a width of the apertures in the set of apertures, (b) a width of the first set of mirrors, (c) a width of reflective surfaces in the reflective layer, and (d) a width of surfaces of the detector elements positioned to receive the further reflected light.

15. The display of claim 12, wherein the reflective layer comprises a set of mirrored surfaces, each of the mirrored surfaces being surrounded by light absorbing material.

16. The display of claim 12, wherein the light blocking layer includes first portions above and parallel to a plane of the set of detector elements and second portions in an area that at least partially surrounds the set of detector elements, wherein the second portions are in a plane substantially perpendicular to the plane of the set of detector elements.

17. A method for making an optical fingerprint sensor, comprising:

forming a set of detector elements and a first set of mirrored surfaces above a substrate;

forming a transparent layer above the set of detector elements and the first set of mirrored surfaces; and

forming a light blocking layer above the transparent layer, the light blocking layer having a set of apertures and a second set of mirrored surfaces.

18. The method of claim 17, further comprising:

coating the substrate with a light absorbing layer having openings over the detector elements and at least portions of the first set of mirrored surfaces.

19. The method of claim 17, wherein forming the light blocking layer further comprises etching away portions of the transparent layer and forming a light absorbing layer in the etched portions of the transparent layer.

20. The method of claim 19, wherein the etched portions of the transparent layer form steps on which a portion of the light absorbing layer is formed.