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

• US 10,437,974 B2
• Filed: 01/04/2018
• Issued: 10/08/2019
• Est. Priority Date: 06/18/2015
• Status: Active Grant

• Current Assignee: Shenzhen Goodix Technology Co., Ltd.
• Original Assignee: Shenzhen Goodix Technology Co., Ltd.
• Inventors: He, Yi, Pi, Bo
• Primary Examiner(s): Strege, John B
• Application Number:
  US15/862,590
• Publication Number:
  US 20180129798A1
• Time in Patent Office: 642 Days
• CPC Class Codes: G06F 21/32 using biometric data, e.g. fingerprints, iris scans or voiceprints
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G06V 10/141 Control of illumination
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: G06V 40/1318 using electro-optical elements or layers, e.g. electroluminescent sensing
• CPC Class Codes: G06V 40/1324 by using geometrical optics, e.g. using prisms G06V40/1312 takes precedence
• CPC Class Codes: G06V 40/1365 Matching; Classification
• CPC Class Codes: G06V 40/1382 Detecting the live character of the finger, i.e. distinguishing from a fake or cadaver finger

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.

Claims

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.

21. The device as in claim 12, 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.

22. 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 collimators are elongated channels in a direction perpendicular to the display panel and the optical layer between the optical collimators and the display is structured to direct the angled probe light from the display panel to be substantially perpendicular to the display panel to enter the optical collimators while directing a portion of the probe light from the display panel that is perpendicular to the display panel to be away from the direction of the optical collimators.

23. The device as in claim 22, 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.

24. The device as in claim 22, wherein the one or more optical filters are designed to filter out IR light.

25. The device as in claim 22, wherein the one or more optical filters are designed to filter out UV light.

26. The device as in claim 22, 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.

27. The device as in claim 22, wherein:

the array of optical collimators includes a substrate having an array of through holes formed in the substrate as the optical collimators.

28. The device as in claim 22, wherein:

the array of optical collimators includes an array of optical waveguides or optical fibers.

29. The device as in claim 22, 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.

30. The device as in claim 22, 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.

31. The device as in claim 22, 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.

32. 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 captures different fingerprint patterns at different times to monitor time-domain evolution of the fingerprint ridge pattern deformation that indicates time-domain evolution of a press force from the contact input.

33. The device as in claim 32, 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.

34. The device as in claim 32, wherein the one or more optical filters are designed to filter out IR light.

35. The device as in claim 32, wherein the one or more optical filters are designed to filter out UV light.

36. The device as in claim 32, 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.

37. The device as in claim 32, wherein:

the array of optical collimators includes a substrate having an array of through holes formed in the substrate as the optical collimators.

38. The device as in claim 32, wherein:

the array of optical collimators includes an array of optical waveguides or optical fibers.

39. The device as in claim 32, 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.

40. The device as in claim 32, 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.

41. The device as in claim 32, 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.

42. The device as in claim 32, 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.