Display integrated optical fingerprint sensor with angle limiting reflector

Patent metadata

Field	Value
Publication number	US-10303919-B2
Application number	US-201815944591-A
Country	US
Kind code	B2
Filing date	Apr 3, 2018
Priority date	Dec 3, 2015
Publication date	May 28, 2019
Grant date	May 28, 2019

Abstract

An optical sensor for imaging an input object, such as a fingerprint, on a sensing region of a display is disclosed. The sensor includes a transparent substrate having a first side and a second side opposite the first side. An array of detector elements is positioned above the first side of the transparent substrate and an angle limiting reflector is positioned below the second side of the transparent substrate. The angle limiting reflector is configured to reflect light incident on the angle limiting reflector within a limited acceptance angle towards the array detector elements.

First claim

The invention claimed is:

1. An optical sensor for imaging a biometric input object in a sensing region, comprising:
a set of display elements and an array of detector elements positioned below the sensing region, wherein the array of detector elements is positioned to detect light incident from below the array of detector elements;
a baffle arrangement positioned below the set of display elements and the array of detector elements, wherein the baffle arrangement includes an array of openings positioned to collimate light incident from below the baffle arrangement; and
a reflective layer positioned below the baffle arrangement, the reflective layer positioned to reflect light towards the array of detector elements.

2. The optical sensor of claim 1 , wherein the baffle arrangement comprises a light absorbing material.

3. The optical sensor of claim 2 , wherein the array of openings comprises a transparent material.

4. The optical sensor of claim 2 , wherein the array of openings comprises a semitransparent material.

5. The optical sensor of claim 1 , wherein the array of openings have a rectangular cross section.

6. The optical sensor of claim 1 , wherein the array of openings have an elliptical or circular cross section.

7. The optical sensor of claim 1 , wherein the reflective layer comprises a plurality of reflectors arranged to direct light to the detector elements.

8. The optical sensor of claim 7 , wherein the plurality of reflectors are one of parabolic, spherical, aspherical or elliptical.

9. The optical sensor of claim 1 , wherein the reflective layer comprises a dichroic reflector configured to reflect first light of a first range of wavelengths and pass second light of a second range of wavelengths.

10. The optical sensor of claim 1 , wherein the set of display elements and the array of detector elements are positioned in the same plane.

11. The optical sensor of claim 1 , further comprising:
a light shield positioned between the sensing region and the array of detector elements.

12. The optical sensor of claim 1 , wherein the baffle arrangement comprises:
a substrate;
a first set of sidewalls positioned on the substrate and formed from a light absorbing material; and
a second set of sidewalls positioned above the substrate and formed from the light absorbing material; the first set of sidewalls and the second set of sidewalls forming the array of openings.

13. The optical sensor of claim 12 , wherein the reflective layer is formed on the substrate.

14. The optical sensor of claim 12 , wherein the first set of sidewalls are positioned in a first layer and the second set of sidewalls are positioned in a second layer, the second layer being above the first layer.

15. The optical sensor of claim 12 , wherein the array of openings comprise a transparent material.

16. A display for imaging a biometric input object in a sensing region, comprising:
a transparent substrate having a first side and a second side opposite the first side, wherein the transparent substrate is positioned below the sensing region;
a set of display elements positioned above the first side of the transparent substrate, the set of display elements providing illumination for the imaging the biometric input object;
an array of detector elements positioned above the first side of the transparent substrate, wherein the array of detector elements is positioned to detect light incident from below the array of detector elements;
a baffle arrangement positioned below the set of display element, wherein the baffle arrangement is formed of light absorbing material and wherein the light absorbing material includes gaps defining an array of apertures positioned to collimate light incident from below the baffle arrangement; and
a reflective layer positioned below the baffle arrangement, the reflective layer positioned to reflect light towards the array of detector elements.

17. The display of claim 16 , wherein the baffle arrangement comprises sidewalls forming the array of apertures and wherein the sidewalls are straight.

18. The display of claim 16 , wherein the baffle arrangement comprises sidewalls forming the array of apertures and wherein the sidewalls are angular.

19. The display of claim 16 , wherein the baffle arrangement comprises:
a first layer, the first layer comprising first sidewalls made of the light absorbing material orientated in a first direction; and
a second layer, the second layer comprising second sidewalls made of the light absorbing material orientated in a second direction, wherein the second layer is positioned above the first layer and wherein the second direction is different from the first direction.

20. The display of claim 16 , wherein the set of display elements and the array of detector elements are positioned in the same plane.

Assignees

• Synaptics Inc

Inventors

• Mienko Marek
• Smith Patrick
• Fomani Arash Akhavan
• Small Jeffrey A

Classifications

• H01L27/14685

  Electricity · mapped topic

• G06K9/00073

  Physics · mapped topic

• H01L27/14629

  Electricity · mapped topic

• H01L27/3234

  Electricity · mapped topic

• H01L31/0236

  Electricity · mapped topic