Display Pixel Patterned Illumination for Fingerprint Sensing
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Solution Overview
Problem
Conventional optical fingerprint sensors are too bulky for mobile devices and struggle to detect fine ridge and valley features through thick layers like cover glass, requiring cutouts and mechanical buttons, which complicates device design and user experience.
Innovation Solution
An electronic device with a display that acts as a sensing surface, using patterned illumination to selectively illuminate display pixels and acquire image data from detector pixels, allowing for optical imaging of fingerprints without the need for a cutout or mechanical buttons, by leveraging the display pixels and detector pixels to reflect light and process images effectively through the cover layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical fingerprint sensors are used, then fingerprint imaging capability is achieved, but device size becomes too bulky for mobile devices
Solution Approach 1:
The display screen serves dual functions: as a visual display and as an optical fingerprint sensor. The display pixels can be configured to illuminate the fingerprint and the same or adjacent pixels detect reflected light, eliminating the need for a separate optical sensor module and reducing overall device volume.
Solution Approach 2:
The patent combines the fingerprint sensing function with the display function by integrating both illumination and detection capabilities into the display pixel array, merging two separate components (display and optical sensor) into a single multi-functional element.
2Device complexity
If capacitive fingerprint sensors are used to detect through thick cover glass, then sensing capability is reduced, but device design becomes simpler
Solution Approach 1:
The patent introduces patterned illumination through specific display pixels as an intermediary to enhance the optical contrast of fingerprint features. By selectively illuminating certain pixel patterns and detecting the reflected light, the system improves the ability to distinguish ridge and valley features through the cover glass while maintaining device design simplicity.
3Measurement precision
If cutouts are formed in cover glass for discrete capacitive sensors, then fingerprint sensing is improved, but device surface becomes non-flush and manufacturing is complicated
Solution Approach 1:
The display screen serves dual functions: as a visual display and as an optical fingerprint sensor. The display pixels can be configured to illuminate the fingerprint and the same or adjacent pixels detect reflected light, eliminating the need for a separate optical sensor module and reducing overall device volume.
4Reliability
If conventional optical sensors are used, then fingerprint detection is achieved, but the sensor cannot be integrated into mobile devices due to size constraints
Solution Approach 1:
The display screen serves dual functions: as a visual display and as an optical fingerprint sensor. The display pixels can be configured to illuminate the fingerprint and the same or adjacent pixels detect reflected light, eliminating the need for a separate optical sensor module and reducing overall device volume.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the detection of fingerprints through thick cover glass without the need for cutouts or mechanical buttons, providing a flush device surface and improved user experience by using the display as both an imaging and sensing component.
Implementation Method 1
selectively illuminate one or more of the display pixels according to a pattern
Implementation Method 2
acquire image data, from one or more detector pixels of the display, of the input object in contact with the sensing surface, wherein the image data corresponds to light from the illuminated display pixels that is reflected at the sensing surface of the display
Data Source
AI summary
Systems and methods for optical imaging are disclosed. The systems and methods include a display for imaging an input object. The display includes a sensing surface; a plurality of display pixels; a plurality of detector pixels; and a processing system. The processing system is configured to determine a location of the input object relative to the sensing surface; illuminate one or more display pixels of the plurality of display pixels according to a pattern depending on the location of the input object; and acquire image data of the input object from one or more detector pixels of the plurality of detector pixels, wherein the image data corresponds to light from the one or more display pixels that is reflected at the sensing surface.