OPTICAL COLLIMATORS FOR UNDER-SCREEN OPTICAL SENSOR MODULE FOR ON-SCREEN FINGERPRINT SENSING

• US 20170270342A1
• Filed: 06/07/2017
• Published: 09/21/2017
• 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
• Granted Patent: US 10,410,037 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 21/32 using biometric data, e.g. fingerprints, iris scans or voiceprints
• CPC Class Codes: G06F 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 2221/2133 Verifying human interaction, e.g., Captcha
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G06F 3/044 by capacitive 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 40/1341 Sensing with light passing through the finger
• CPC Class Codes: G06V 40/1365 Matching; Classification
• CPC Class Codes: G06V 40/1394 using acquisition arrangements

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.

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; and

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.

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 optical sensor module includes one or more optical filters in an optical path to the optical sensor module to reduce light at wavelengths different from the light emitted by the light emitting display pixels.

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

each optical collimator in the array of optical collimators is structured to transmit light in directions along or close an axis of the optical collimator while blocking light in other directions and to have a small transmission numerical aperture to achieve a high spatial resolution by the array of optical collimators.

10. 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.

11. The device as in claim 10, 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.

12. The device as in claim 10, 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.

13. The device as in claim 1, 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 ratios 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.

14. The device as in claim 1, 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.

15. 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.

16. 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; and

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, 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, and 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.

17. The device as in claim 16, 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.

18. The device as in claim 16, 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.

19. The device as in claim 16, further comprising:

a device electronic control module coupled to the display panel structure to supply power to the light emitting display pixels and to turn off power to the light emitting display pixels in a sleep mode, and

wherein the device electronic control module is configured to wake up the display panel structure from the sleep mode when the optical sensor module detects the presence of a person'"'"'s skin.

20. The device as in claim 16, wherein:

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

21. The device as in claim 16, wherein:

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

22. The device as in claim 16, 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.

23. The device as in claim 16, wherein:

the optical sensor module is configured to, in addition to detecting fingerprints, also detect a biometric parameter different form a fingerprint by optical sensing to indicate whether a touch at the top transparent layer associated with a detected fingerprint is from a live person; and

the device further includes a device electronic control module configured to grant a user'"'"'s access to the device if both (1) a detected fingerprint matches a fingerprint an authorized user and (2) the detected biometric parameter indicates the detected fingerprint is from a live person.