Optical sensing performance of under-screen optical sensor module for on-screen fingerprint sensing

Patent metadata

Field	Value
Publication number	US-10437974-B2
Application number	US-201815862590-A
Country	US
Kind code	B2
Filing date	Jan 4, 2018
Priority date	Jun 18, 2015
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

Abstract

Devices and optical sensor modules are provided for provide on-screen optical sensing of fingerprints by using a under-screen optical sensor module that captures and detects returned light that is emitted by the display screen for displaying images and that is reflected back by the top surface of the screen assembly. Optical collimators are provided in the under-screen optical sensor module to enhance the optical imaging performance. Techniques for reducing the environmental light in the optical sensing are provided.

First claim

What is claimed is:

1. An electronic device capable of detecting a fingerprint by optical sensing, comprising:
a display panel that includes light emitting display pixels, each pixel operable to emit light for forming a portion of a display image;
a top transparent layer formed over the display panel as an interface for being touched by a user and for transmitting the light from the display panel to display images;
an optical sensor module located below the display panel to receive light that is emitted by at least a portion of the light emitting display pixels and is returned from the top transparent layer to detect a fingerprint, the optical sensor module including an optical sensor array of optical detectors and an array of optical collimators located between the display panel and the optical sensor array to collect the returned light from the display panel and to separate light from different locations in the top transparent layer while directing the collected returned light to the optical sensor array, wherein the array of optical collimators is spaced from the optical sensor array to effectuate a pinhole camera effect that enhances an optical imaging resolution of the optical sensor array; and
one or more optical filters placed between a top surface of the top transparent layer and the optical sensor array of the optical sensor module to block or reduce an amount of environmental light from entering the optical sensor array,
wherein the optical sensor module is structured to measure returned probe light at two or more different wavelengths emitted by light emitting display pixels in the display panel to compare an extinction ratio of the probe light at the two or more different wavelengths as the second signal indicative of whether the received contact is from a live person.

2. The device as in claim 1 , wherein:
the array of optical collimators and spacing between the array of optical collimators and the optical sensor array are structured to cause images of a field of view of the optical collimators at the optical sensor array to be spatially separated.

3. The device as in claim 1 , wherein the one or more optical filters are designed to filter out IR light.

4. The device as in claim 1 , wherein the one or more optical filters are designed to filter out UV light.

5. The device as in claim 1 , wherein:
the optical sensor module includes an optically absorbing material between the optical collimators in the array of optical collimators to absorb light that are not collected by the optical collimators.

6. The device as in claim 1 , wherein:
the array of optical collimators includes a substrate having an array of through holes formed in the substrate as the optical collimators.

7. The device as in claim 1 , wherein:
the array of optical collimators includes an array of optical waveguides or optical fibers.

8. The device as in claim 1 , wherein:
the array of optical collimators includes a micro lens array of micro lenses and each micro lens focus received light without imaging the received light.

9. The device as in claim 1 , wherein the optical sensor module further includes an optical layer between the optical collimators and the display panel to select angled probe light returned from the display panel to enter the optical collimators while reducing an amount of the returned probe light that is perpendicular to the display panel and enters the optical collimators.

10. The device as in claim 1 , wherein the display panel operates in a flash mode to cause a portion of the light emitting display pixels in the display panel to flash at a light emission level higher than a light emission level in displaying images to detect a presence of a finger and to obtain a fingerprint of the finger.

11. The device as in claim 1 , further comprising sidewalls formed on sides of the optical sensor array to block environmental light from entering the optical sensor array at large incident angles.

12. An electronic device capable of detecting a fingerprint by optical sensing, comprising:
a display panel that includes light emitting display pixels, each pixel operable to emit light for forming a portion of a display image;
a top transparent layer formed over the display panel as an interface for being touched by a user and for transmitting the light from the display panel to display images;
an optical sensor module located below the display panel to receive light that is emitted by at least a portion of the light emitting display pixels and is returned from the top transparent layer to detect a fingerprint, the optical sensor module including an optical sensor array of optical detectors and an array of optical collimators located between the display panel and the optical sensor array to collect the returned light from the display panel and to separate light from different locations in the top transparent layer while directing the collected returned light to the optical sensor array, wherein the array of optical collimators is spaced from the optical sensor array to effectuate a pinhole camera effect that enhances an optical imaging resolution of the optical sensor array; and
one or more optical filters placed between a top surface of the top transparent layer and the optical sensor array of the optical sensor module to block or reduce an amount of environmental light from entering the optical sensor array,
wherein the optical sensor module further includes an optical layer between the optical collimators and the display panel to select angled probe light returned from the display panel to enter the optical collimators while reducing an amount of the returned probe light that is perpendicular to the display panel and enters the optical collimators, and
wherein the optical layer includes an optical diffraction pattern that diffracts the returned probe light to direct the angled probe light returned from the display panel to enter the optical collimators.

13. The device as in claim 12 , wherein:
the array of optical collimators and spacing between the array of optical collimators and the optical sensor array are structured to cause images of a field of view of the optical collimators at the optical sensor array to be spatially separated.

14. The device as in claim 12 , wherein the one or more optical filters are designed to filter out IR light.

15. The device as in claim 12 , wherein the one or more optical filters are designed to filter out UV light.

16. The device as in claim 12 , wherein:
the optical sensor module includes an optically absorbing material between the optical collimators in the array of optical collimators to absorb light that are not collected by the optical collimators.

17. The device as in claim 12 , wherein:
the array of optical collimators includes a substrate having an array of through holes formed in the substrate as the optical collimators.

18. The device as in claim 12 , wherein:
the array of optical collimators includes an array of optical waveguides or optical fibers.

19. The device as in claim 12 , wherein:
the array of optical collimators includes a micro lens array of micro lenses and each micro lens focus received light without imaging the received light.

20. The device as in claim 12 , wherein the display panel operates in a flash mode to cause a portion of the light emitting display pixels in the display panel to flash at a light emission level higher than a light emission level in displaying images to detect a presence of a finger and to obtain a fingerprint of the finger.

Assignees

• Shenzhen Goodix Tech Co Ltd

Inventors

• He Yi
• Pi Bo

Classifications

• G06V40/1324

  by using geometrical optics, e.g. using prisms (G06V40/1312 takes precedence) · CPC title

• G06V10/141

  Control of illumination · CPC title

• G06F21/32 Primary

  using biometric data, e.g. fingerprints, iris scans or voiceprints · CPC title

• G06F3/042

  by opto-electronic means · CPC title

• G06F3/0412

  Digitisers structurally integrated in a display · CPC title