Light-field Sensor Under-display Fingerprint Interference
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Solution Overview
Problem
Existing fingerprint sensing technologies under display panels face interference issues due to the structure of the display panel, which cannot be completely eliminated by existing methods, especially when the spatial frequency of the panel matches that of the target object, leading to Moire patterns and other distortions.
Innovation Solution
A fingerprint identification system utilizing a light-field image sensor with subarrays of sensing pixels that capture images from different directions, combined with a sensing circuit that generates and shifts sub-images to reconstruct an image data, reducing interference by emitting light from various directions and using micro-lenses with light shielding structures to avoid optical crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a sensor under a display panel is utilized to sense a fingerprint, then the fingerprint sensing function is integrated into the display structure, but interference from the display panel structure affects the sensed image quality
Solution Approach 1:
The patent transitions from conventional 2D fingerprint sensing to 3D light-field sensing by introducing angular dimension. The light-field image sensor captures not only spatial information but also directional information of light rays, enabling the system to sense fingerprints from multiple angles and depths, thereby overcoming the interference patterns caused by the display panel structure.
Solution Approach 2:
The patent changes the sensing parameters by using micro-lenses with different focal lengths and configurations to capture light fields from various directions. By varying the angular parameters of light capture and implementing multi-focus imaging, the system can reconstruct high-quality fingerprint images that are less susceptible to display panel interference patterns.
2Device complexity
If conventional sensing methods are used under the display panel, then the system structure is simple, but Moire patterns and distortions occur when spatial frequencies match
Solution Approach 1:
The patent divides the sensing system into multiple functional components: array of micro-lenses, light-field image sensor with multiple pixel arrays, and image reconstruction circuitry. Each component performs a specific function in capturing and processing light-field information, allowing the system to eliminate Moire patterns through computational reconstruction while maintaining manageable structural complexity.
Solution Approach 2:
The patent introduces micro-lenses as intermediary optical elements between the display panel and the image sensor. These micro-lenses focus light from different directions onto corresponding pixel arrays, acting as a mediator that transforms the complex light field into structured signals that can be reconstructed into accurate fingerprint images without Moire artifacts.
3Measurement precision
If light-field sensing with multiple subarrays is implemented, then interference from display panel structure is reduced, but device complexity increases
Solution Approach 1:
The patent designs the light-field image sensor to perform multiple functions: capturing spatial information, capturing angular information, and enabling both contact and floating touch sensing modes. The same multi-subarray structure serves both fingerprint identification and gesture recognition, reducing the need for separate sensing systems and justifying the increased complexity through functional consolidation.
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
This approach effectively reduces the impact of display panel structure on sensed images, enabling accurate fingerprint identification and allowing for floating touch functionality without direct contact, while also improving signal-to-noise ratio and reducing overall system height.
Implementation Method 1
The sensing pixels are to capture images of an object on or in proximity to the display panel by sensing lights from different directions
Implementation Method 2
using micro-lenses with light shielding structures to avoid optical crosstalk
Implementation Method 3
due to the structure of the display panel, interference will affect the sensed image(s)
Data Source
AI summary
A sensing device includes a light-field image sensor and a sensing circuit. The light-field image sensor includes a plurality of subarrays. One of the subarrays corresponds to sensing pixels. The sensing pixels are to capture images of an object on or in proximity to a display panel by sensing lights from different directions. The sensing circuit is to generate a plurality of sub-images of the object according to sensing signals of the sensing pixels and shift each of the sub-images of the object by an off-set to generate an image data.