Display Panel Sub-Pixel Overlap for Accurate Fingerprint Sensing
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Solution Overview
Problem
The integration of photosensitive units in display panels, such as OLED display panels, results in reduced light receiving areas and recognition accuracy due to the influence of sub-pixels emitting different colors, leading to distorted photoelectric signals and decreased fingerprint recognition accuracy.
Innovation Solution
The display panel design incorporates a sub-pixel array with a delta shape arrangement, where photosensitive units are positioned under gaps between sub-pixels, ensuring equal overlapping areas with each sub-pixel, and employs a Y-shaped structure for photosensitive units to maximize light reception, reducing the variation in light filtering and enhancing signal strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple planar pixel structure is used, then the manufacturing process is simple, but the viewing angle is narrow and image quality deteriorates at oblique angles
Solution Approach 1:
The patent transitions from a two-dimensional planar pixel structure to a three-dimensional microlens array structure. Each pixel includes a light-emitting element positioned at the bottom and a hemispherical or dome-shaped microlens positioned above it, creating a vertical dimension that enables light to be emitted in multiple directions simultaneously, thereby expanding the viewing angle while maintaining manufacturing feasibility through established semiconductor fabrication processes.
Solution Approach 2:
The patent employs composite material structures where transparent refractive materials (such as resin or glass) are combined with light-emitting elements (LEDs, OLEDs, or micro-discharge lamps). The microlens is made of transparent material with a specific refractive index to refract and redirect light, creating a composite structure that optimizes both light extraction efficiency and viewing angle characteristics.
2Device complexity
If a simple planar pixel structure is used, then the device structure is simple, but light extraction efficiency is low due to total internal reflection
Solution Approach 1:
The introduction of a vertical dimension through the microlens structure allows light to be extracted in multiple directions rather than being constrained to a planar interface. The curved surface of the microlens creates varying angles of incidence for light rays, enabling those that would normally undergo total internal reflection at the planar interface to be refracted outward, thereby significantly improving light extraction efficiency.
Solution Approach 2:
The patent changes the geometric parameters of the light extraction interface by introducing curved surfaces with specific radii of curvature. The microlens is designed with optimized curvature parameters to control the refraction of light, transforming the light extraction mechanism from planar total internal reflection to curved surface refraction, thereby enhancing extraction efficiency.
3Ease of manufacture
If a simple planar pixel structure is used, then the manufacturing process is simple, but brightness uniformity is poor with dark corners
Solution Approach 1:
The microlens structure introduces a vertical dimension that redirects light from the bottom-emitting elements toward the front surface in a controlled manner. The curved geometry of the microlens ensures that light is distributed more uniformly across the viewing area, eliminating the dark corner effect characteristic of planar structures while maintaining compatibility with standard semiconductor manufacturing processes.
Solution Approach 2:
The patent optimizes geometric parameters such as the radius of curvature, height, and diameter of the microlens to control light distribution patterns. By carefully selecting these parameters, the design achieves uniform brightness across the display area, transforming the non-uniform light distribution of planar structures into a uniformly illuminated output.
4Device complexity
If a simple planar pixel structure is used, then the device is simple, but light is emitted in only one direction limiting viewing angle
Solution Approach 1:
The patent adds a vertical dimension to the light emission path by positioning microlenses above the light-emitting elements. This three-dimensional configuration enables light to be emitted simultaneously in multiple directions (upward through the microlens and sideways), transforming the single-direction emission of planar structures into multi-directional emission without significantly increasing device complexity.
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 design improves fingerprint recognition accuracy by minimizing signal distortion and maximizing light reception, allowing for full-screen fingerprint recognition without the need for correction algorithms.
Implementation Method 1
a light emitting element and a microlens positioned above the light emitting element, in each pixel of the display panel
Data Source
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AI summary
A display panel is provided. The display panel includes: a sub-pixel array and a plurality of photosensitive units. The sub-pixel array includes a first sub-pixel, a second sub-pixel and a third sub-pixel that are capable of emitting light of different colors. The plurality of photosensitive units are disposed under a light-emitting surface of the sub-pixel array; each of the plurality of photosensitive unit includes a photosensitive device, and the photosensitive device includes a photosensitive layer. An orthographic projection of the photosensitive layer in the photosensitive device on a panel surface of the display panel has overlapping regions with orthographic projections of the first sub-pixel, the second sub-pixel and the third sub-pixel on the panel surface of the display panel.