On-LCD screen optical fingerprint sensing based on optical imaging with lens-pinhole module and other optical designs

• US 10,303,921 B1
• Filed: 07/10/2018
• Issued: 05/28/2019
• Est. Priority Date: 02/26/2018
• 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): Shah, Utpal D
• Application Number:
  US16/032,048
• Time in Patent Office: 322 Days
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02F 1/13318 Circuits comprising a photodetector
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133526 Lenses, e.g. microlenses or Fresnel lenses
• CPC Class Codes: G06V 10/147 Details of sensors, e.g. sensor lenses fingerprint or palmprint sensors G06V40/13; vascular sensors G06V40/145; eye sensors G06V40/19
• 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 40/1329 Protecting the fingerprint sensor against damage caused by the finger
• CPC Class Codes: G06V 40/45 Detection of the body part being alive

Abstract

Devices and optical sensor modules are provided for provide on-screen optical sensing of fingerprints by using an under-screen optical sensor module that captures and detects light from a fiber on top of the screen. Various implementations of the under-LCD optical sensor modules are provided, including different optical imaging module designs for under-LCD optical sensing, invisible under-LCD optical sensor modules based on concealing optical transmissive features or regions under the LCD opaque borders and optical sensing of topographical features associated with inner tissues of a finger.

Claims

1. A device capable of detecting a fingerprint by optical sensing, comprising:

a liquid crystal display (LCD) screen that provides touch sensing operations and includes a LCD display panel structure to display images, wherein the LCD display panel includes a backlighting module to produce backlight for displaying the images;

a top transparent layer formed over the LCD screen as an interface for being touched by a user for the touch sensing operations and for transmitting the light from the LCD display panel structure to display images to a user and for transmitting the probe light for optical sensing;

an illumination probe light source that produces probe light to illuminate a sensing area of the top transparent layer for optical sensing; and

an optical sensor module located below the LCD display panel structure to receive returned probe light that passes through the LCD screen for optical sensing, wherein the optical sensor module includes;

an optical sensor array of optical detectors to convert the received probe light from the LCD screen that carries a fingerprint pattern of the user into detector signals representing the fingerprint pattern,

a pinhole layer located between the LCD screen and the optical sensor array and structured to include a pinhole that is structured to produce a large optical field of view in collecting the returned probe light and to transmit the collected probe light towards the optical sensor array, and

a lens located between the pinhole layer and the optical sensor array to receive the transmitted probe light from the pinhole and to focus the received probe light onto the optical sensor array for optical imaging at an enhanced spatial imaging resolution at the optical sensor array when compared to a lower spatial imaging resolution when using the pinhole to project light onto the optical sensor array without the lens.

2. The device as in claim 1, wherein the optical sensor module includes:

an optically transparent structure located between the lens and the optical sensor array to direct light from the lens to the optical sensor array and structured to have a refractive property and a thickness to reduce an optical distortion at the optical sensor array.

3. The device as in claim 2, wherein:

the optically transparent structure between the lens and the optical sensor array includes an optically transparent spacer layer and an optically transparent protection layer formed over the optical detectors of the optical sensor array.

4. The device as in claim 3, wherein:

the optically transparent protection layer includes an optical bandpass filter that transmits the probe light while blocking light at other wavelengths.

5. The device as in claim 1, wherein the optical sensor module includes:

first optically transparent layers located between the display panel and the pinhole layer; and

second optically transparent layers located below the pinhole layer and the lens and above the optical sensor array,

wherein refractive indices and thickness values of the second optically transparent layers are selected based on both (1) refractive indices and thickness values of the first optically transparent layers and (2) an optical power of the lens so as to reduce an optical distortion in an optical image captured at the optical sensor array.

6. The device as in claim 5, wherein:

the first optically transparent layers located between the display panel and the pinhole layer and the second optically transparent layers located below the pinhole layer and the lens and above the optical sensor array are arranged symmetrically with respect to the pinhole layer.

7. The device as in claim 1, wherein the optical sensor module includes:

an optically transparent layer located between the display panel and the pinhole layer and being in contact with the pinhole layer, wherein the pinhole layer has a refractive index higher than a refractive index of the optically transparent layer in contact with the pinhole layer.

8. The device as in claim 1, further including:

a gradient transmission filter located between the display panel and the optical sensor array to modify a spatial optical intensity distribution of light received at the optical sensor array after passing through the pinhole and the lens,

wherein the gradient transmission filter is structured to exhibit a high optical attenuation at or near a center of the pinhole and a decreasing optical attenuation from the center of the pinhole radially outward to counter a spatial variation of an optical intensity distribution of light caused by the pinhole.

9. The device as in claim 1, further comprising:

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.

10. The device as in claim 1, wherein:

the LCD display panel structure includes a light diffuser layer that diffuses light and the light diffuser includes holes at a selected area above the optical sensor module to allow light to be transmitted to reach the optical sensor module.

11. The device as in claim 1, comprising:

a LCD illumination light module coupled to the LCD display panel structure to provide backlighting light to the LCD display panel structure for displaying images;

wherein the LCD display panel structure includes a backlighting waveguide layer that coupled to receive the backlighting light from the LCD illumination light module to guide the received backlighting light to illuminate the LCD display structure an optical reflector layer formed on a bottom region of the LCD display panel structure to reflect light back to the LCD display panel structure; and

holes formed in a selected area above the optical sensor module to allow light to be transmitted to reach the optical sensor module.

12. The device as in claim 1, comprising:

an optical reflector layer formed on a bottom region of the LCD display panel structure to reflect light back to the LCD display panel structure, wherein the optical reflector layer includes a selected area above the optical sensor module to allow light to be transmitted to reach the optical sensor module.

13. The device as in claim 1, comprising:

one or more probe light sources formed under the LCD display panel structure to project the probe light to pass through the LCD display panel structure to illuminate an object or finger on top of or in touch with a top surface of the LCD display panel structure to direct reflected probe light towards the optical sensor module; and

a device electronic control module coupled to the display panel structure to supply power to the one or more probe light sources to turn off power to the one or more probe light sources in a sleep mode, and

wherein the device electronic control module is configured to wake up the LCD display panel structure from the sleep mode when the optical sensor module detects the presence of a person'"'"'s skin at the designated fingerprint sensing region of the top transparent layer.

14. The device as in claim 13, wherein:

the device electronic control module is configured to operate one or more probe light sources to intermittently emit the probe light, while turning off power to the LCD display panel structure, when the LCD display panel structure is in the sleep mode, to direct the intermittently probe light to the designated fingerprint sensing region of the top transparent layer for monitoring whether there is a person'"'"'s skin in contact with the designated fingerprint sensing region for waking up the device from the sleep mode.

15. The device as in claim 1, further comprising:

a device electronic control module that grants a user'"'"'s access to the device if a detected fingerprint matches a fingerprint an authorized user,

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 electronic control module is 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 liver person.

16. The device as in claim 1, comprising:

a device electronic control module coupled to the optical sensor module to receive information on multiple detected fingerprints obtained from sensing a touch of a finger, wherein the device electronic control module measures a change in the multiple detected fingerprints and determines a touch force that causes the measured change.

17. The device as in claim 1, wherein:

the LCD screen includes a peripheral opaque border surrounding a central area of the LCD display panel structure and covering a narrow peripheral border of the LCD display panel structure such that the central area of the LCD display panel structure within the peripheral opaque border displays images under illumination by the backlight from the backlighting module;

the optical sensor module is located below the LCD screen and positioned underneath the peripheral opaque border to be spatially offset from central area of the LCD display panel structure to receive returned probe light that passes through the LCD screen for optical sensing; and

the LCD display panel structure includes one or more extra transmission holes or regions within an area that is at least partially covered by the peripheral border and is positioned above the optical sensor module to allow probe light to pass through the LCD display panel structure to reach the optical sensor module for optical sensing.

18. The device as in claim 17, wherein:

the LCD display panel structure includes a light diffuser layer that diffuses light and the light diffuser includes holes to form part of the extra transmission holes or regions within the area that is covered by the peripheral border and is positioned above the optical sensor module to allow probe light to pass through the LCD display panel structure to reach the optical sensor module for optical sensing.

19. The device as in claim 17, wherein:

the LCD display panel structure includes a backlighting waveguide layer that coupled to receive the backlighting light from the LCD illumination light module to guide the received backlighting light to illuminate the LCD display structure and an optical reflector layer formed on a bottom region of the LCD display panel structure to reflect light back to the LCD display panel structure; and

the optical reflector layer includes holes to form part of the extra transmission holes or regions within the area that is covered by the peripheral border and is positioned above the optical sensor module to allow probe light to pass through the LCD display panel structure to reach the optical sensor module for optical sensing.

20. The device as in claim 17, wherein:

the LCD display panel structure includes;

a LCD assembly layer that includes a LCD layer and additional layers to form LCD pixels for displaying images;

a LCD illumination light module coupled to the LCD display panel structure to provide backlighting light to the LCD assembly layer for displaying images

a backlighting waveguide layer that coupled to receive the backlighting light from the LCD illumination light module to guide the received backlighting light to illuminate the LCD assembly layer;

a light diffusion layer between the backlighting waveguide layer and the LCD assembly layer to diffuse light and structured to include a void underneath the peripheral border at a location of the optical sensor module to facilitate light to pass through the LCD display panel structure to reach the optical sensor module for optical sensing; and

an optical reflector layer formed below the backlighting waveguide layer to reflect light back to the LCD display panel structure and structured to have a void underneath the peripheral border at a location of the optical sensor module so that the optical sensor module is placed underneath the backlighting waveguide layer to receive returned probe light above the LCD screen via transmitted light through the backlighting waveguide layer.

21. The device as in claim 20, further comprising:

a light coupler located below the LCD assembly layer and above the backlighting waveguide layer to facilitate light to pass through the LCD display panel structure to reach the optical sensor module for optical sensing.

22. A device capable of detecting a fingerprint by optical sensing, comprising an optical sensor module that receives incident light carrying fingerprint information and captures an image of the incident light for optical sensing, wherein the optical sensor module includes:

an optical sensor array of optical detectors to convert the received incident light that carries a fingerprint pattern of the user into detector signals representing the fingerprint pattern,

a pinhole layer located in an optical path of the incident light to the optical sensor array and structured to include a pinhole that is structured to produce a large optical field of view in collecting the incident light and to transmit the collected incident light towards the optical sensor array, and

a lens located between the pinhole layer and the optical sensor array to receive the transmitted incident light from the pinhole and to focus the received light onto the optical sensor array for optical imaging at an enhanced spatial imaging resolution at the optical sensor array.

23. The device as in claim 22, wherein the optical sensor module includes:

an optically transparent structure located between the lens and the optical sensor array to direct light from the lens to the optical sensor array and structured to have a refractive property and a thickness to reduce an optical distortion at the optical sensor array.

24. The device as in claim 23, wherein:

the optically transparent structure between the lens and the optical sensor array includes an optically transparent spacer layer and an optically transparent protection layer formed over the optical detectors of the optical sensor array.

25. The device as in claim 24, wherein:

the optically transparent protection layer includes an optical bandpass filter that transmits the incident light while blocking light at other wavelengths.

26. The device as in claim 22, wherein the optical sensor module includes:

first optically transparent layers located between the display panel and the pinhole layer; and

second optically transparent layers located below the pinhole layer and the lens and above the optical sensor array,

wherein refractive indices and thickness values of the second optically transparent layers are selected based on both (1) refractive indices and thickness values of the first optically transparent layers and (2) an optical power of the lens so as to reduce an optical distortion in an optical image captured at the optical sensor array.

27. The device as in claim 26, wherein:

the first optically transparent layers located between the display panel and the pinhole layer and the second optically transparent layers located below the pinhole layer and the lens and above the optical sensor array are arranged symmetrically with respect to the pinhole layer.

28. The device as in claim 22, wherein the optical sensor module includes:

an optically transparent layer located in an optical path of the incident light to the pinhole layer and being in contact with the pinhole layer, wherein the pinhole layer has a refractive index higher than a refractive index of the optically transparent layer in contact with the pinhole layer.

29. The device as in claim 22, further including:

a gradient transmission filter located in an optical path of the incident light to the optical sensor array to modify a spatial optical intensity distribution of light received at the optical sensor array after passing through the pinhole and the lens,

wherein the gradient transmission filter is structured to exhibit a high optical attenuation at or near a center of the pinhole and a decreasing optical attenuation from the center of the pinhole radially outward to counter a spatial variation of an optical intensity distribution of light caused by the pinhole.

30. The device as in claim 22, further comprising:

one or more optical filters placed in an optical path of the incident light to the optical sensor array of the optical sensor module to block or reduce an amount of environmental light from entering the optical sensor array.