Under-screen optical sensor module for on-screen fingerprint sensing

Patent metadata

Field	Value
Publication number	US-10410036-B2
Application number	US-201715421249-A
Country	US
Kind code	B2
Filing date	Jan 31, 2017
Priority date	Jun 18, 2015
Publication date	Sep 10, 2019
Grant date	Sep 10, 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.

First claim

What is claimed is:

1. An electronic device capable of detecting a fingerprint by optical sensing, comprising:
a device screen that provides touch sensing operations and includes a display panel structure having 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 device screen as an interface for being touched by a user for the touch sensing operations and for transmitting the light from the display structure to display images to a user;
an optical sensor module located below the display panel structure to receive light that is emitted by at least a portion of the light emitting display pixels of the display structure and is returned from the top transparent layer to detect a fingerprint;
one or more extra illumination light sources placed below the display panel and near the optical sensor module to provide illumination probe light to illuminate a sensing area on the top transparent layer to cause returned probe light from the sensing area to the optical sensor module for optically sensing a touch by the optical sensor module without turning on the light emitting display pixels of the display panel to save power, and to provide additional illumination to the sensing area when the light emitting display pixels of the display panel are turned on to enhance optical sensing sensitivity of optical sensing at the optical sensor module; and
a device electronic control module coupled to control the one or more extra illumination light sources to produce the illumination probe light as pulsed probe light at a pulse duty cycle, and further coupled to the optical sensor module to detect light at the pulse duty cycle to determine whether there is a touch on the top transparent layer before turning on the light emitting display pixels of the display panel structure.

2. The device as in claim 1 , wherein:
the display structure includes a display panel substrate that interfaces with the optical sensor module and supports the light emitting display pixels; and
the optical sensor module includes a transparent block in contact with the display panel substrate to receive the light from the display panel structure, an optical sensor array that receives the light and an optical imaging module that images the received light in the transparent block onto the optical sensor array, wherein the transparent block has a refractive index lower than a refractive index of the display panel substrate.

3. The device as in claim 1 , wherein:
the device electronic control module is 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
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 at the designated fingerprint sensing region of the top transparent layer.

4. The device as in claim 3 , wherein:
the device electronic control module is configured to operate one or more selected light emitting display pixels to intermittently emit light, while turning off power to other light emitting display pixels, when the display panel structure is in the sleep mode, to direct the intermittently emitted 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.

5. The device as in claim 3 , wherein:
the display panel structure includes one or more light emitting diode (LED) lights in addition to the light emitting display pixels; and
the device electronic control module is configured to operate the one or more LED lights to intermittently emit light, while turning off power to light emitting display pixels when the display panel structure is in the sleep mode, to direct the intermittently emitted 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.

6. The device as in claim 1 , 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 live person.

7. The device as in claim 1 , wherein:
in a fingerprint sensing operation, the device electronic control module operates to turn off the light emitting display pixels in one frame to and turn on the light emitting display pixels in a next frame to allow the optical sensor array to capture two fingerprint images with and without the illumination by the light emitting display pixels to reduce background light in fingerprint sensing.

8. The device as in claim 1 , wherein:
the device electronic control module is 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.

9. The device as in claim 8 , wherein:
the change includes a change in the fingerprint image due to the touch force, a change in the touch area due to the touch force, or a change in spacing of fingerprint ridges.

10. The device as in claim 1 , further comprising 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 of the display panel structure.

11. The device as in claim 10 , wherein the one or more optical filters are designed to filter out IR light.

12. An electronic device capable of detecting a fingerprint by optical sensing, comprising:
a device screen that provides touch sensing operations and includes a display panel structure having 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 device screen as an interface for being touched by a user for the touch sensing operations and for transmitting the light from the display structure to display images to a user;
an optical sensor module located below the display panel structure to receive light that is emitted by at least a portion of the light emitting display pixels of the display structure and is returned from the top transparent layer to detect a fingerprint; and
one or more extra illumination light sources placed below the display panel and near the optical sensor module to provide illumination probe light to illuminate a sensing area on the top transparent layer to cause returned probe light from the sensing area to the optical sensor module for optically sensing a touch by the optical sensor module without turning on the light emitting display pixels of the display panel to save power, and to provide additional illumination to the sensing area when the light emitting display pixels of the display panel are turned on to enhance optical sensing sensitivity of optical sensing at the optical sensor module,
wherein:
the displa

Assignees

• Shenzhen Goodix Tech Co Ltd

Inventors

• He Yi
• Pi Bo

Classifications

• G06F3/042

  by opto-electronic means · CPC title

• G06V40/1394

  using acquisition arrangements · CPC title

• G06V10/141

  Control of illumination · CPC title

• G06F3/0412

  Digitisers structurally integrated in a display · CPC title

• G06F2203/04106

  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 title