Optical sensor for integration over a display backplane

Patent metadata

Field	Value
Publication number	US-10169630-B2
Application number	US-201615087971-A
Country	US
Kind code	B2
Filing date	Mar 31, 2016
Priority date	Dec 3, 2015
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

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.

First claim

The invention claimed is:

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.

Assignees

• Synaptics Inc

Inventors

• Fomani Arash Akhavan
• Smith Patrick
• Mienko Marek
• Wickboldt Paul

Classifications

• G01J1/0214 Primary

  Constructional arrangements for removing stray light · CPC title

• G06K9/0008

  Physics · mapped topic

• G02F1/133512

  Light shielding layers, e.g. black matrix (G02F1/136209 takes precedence) · CPC title

• G06K2009/0006

  Physics · mapped topic

• G01J1/0429

  using polarisation elements · CPC title