Display integrated optical fingerprint sensor with angle limiting reflector

• US 10,303,919 B2
• Filed: 04/03/2018
• Issued: 05/28/2019
• Est. Priority Date: 12/03/2015
• Status: Active Grant

• Current Assignee: Fingerprint Cards AB
• Original Assignee: Synaptics Incorporated
• Inventors: Mienko, Marek, Smith, Patrick, Fomani, Arash Akhavan, Small, Jeffrey A.
• Primary Examiner(s): Bradford, Peter
• Application Number:
  US15/944,591
• Publication Number:
  US 20180225501A1
• Time in Patent Office: 420 Days
• CPC Class Codes: G06F 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06V 40/1318 using electro-optical elements or layers, e.g. electroluminescent sensing
• CPC Class Codes: G06V 40/1353 Extracting features related to minutiae or pores
• CPC Class Codes: G06V 40/1359 Extracting features related to ridge properties; Determining the fingerprint type, e.g. whorl or loop
• CPC Class Codes: H01L 27/14623 Optical shielding
• CPC Class Codes: H01L 27/14629 Reflectors
• CPC Class Codes: H01L 27/14685 Process for coatings or optical elements
• CPC Class Codes: H01L 31/02325 the optical elements not being integrated nor being directly associated with the device
• CPC Class Codes: H01L 31/0236 Special surface textures
• CPC Class Codes: H10K 59/65 OLEDs integrated with inorganic image sensors
• CPC Class Codes: H10K 71/00 Manufacture or treatment specially adapted for the organic devices covered by this subclass

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.

Claims

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.