In-Cell Fingerprint Sensor Light Path Structure for Crosstalk Reduction
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Solution Overview
Problem
In display panels with integrated photoelectric sensors for fingerprint identification, crosstalk of light from adjacent valleys or ridges occurs, leading to image blurring due to overlapping light paths, which existing technologies have not effectively addressed.
Innovation Solution
A display panel design featuring a light path structure between the photoelectric sensing structure and the light emitting structure, with a collimation effect achieved through a series of light shielding layers and transmission channels, ensuring that light emitted from one side only reaches the corresponding photoelectric sensor, thereby minimizing crosstalk and improving imaging definition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a photoelectric sensor is integrated inside the display panel for fingerprint identification, then the product thickness is reduced, but light crosstalk from adjacent valleys or ridges occurs causing image blurring
Solution Approach 1:
The patent divides the optical path into multiple independent channels using light shielding layers with light transmission holes. Each light transmission channel is spatially segmented to guide light from specific valleys or ridges to corresponding photoelectric sensors, preventing crosstalk between adjacent sensing regions. This segmentation maintains the in-cell integration benefit while solving the image blurring problem.
Solution Approach 2:
The patent introduces light shielding layers with light transmission holes as intermediary structures between the fingerprint surface and photoelectric sensors. These intermediary layers act as optical guides that selectively transmit light from specific fingerprint features while blocking light from adjacent features, thereby eliminating crosstalk without increasing overall panel thickness significantly.
2Illumination intensity
If light transmission channels are designed with larger aperture to improve light intensity, then more light reaches the sensor, but crosstalk from adjacent valleys or ridges increases
Solution Approach 1:
The patent applies local quality by designing light shielding layers with specifically positioned light transmission holes that have optimized aperture sizes. Each light transmission channel's aperture is locally tailored to allow sufficient light intensity from the corresponding valley or ridge while blocking light from adjacent regions. This local optimization ensures both adequate light intensity and minimal crosstalk.
Solution Approach 2:
The patent resolves the aperture-crosstalk trade-off by transitioning from a two-dimensional aperture size parameter to a three-dimensional spatial configuration. The light shielding layers create vertically stacked light transmission channels with controlled lateral dimensions, allowing the aperture to be small enough to prevent crosstalk while maintaining sufficient light intensity through optimized vertical alignment and spacing.
3Measurement precision
If light shielding layers are added to prevent crosstalk, then imaging definition is improved, but device structure becomes more complex
Solution Approach 1:
The patent merges the light shielding function with the structural layers already present in the display panel. The light shielding layers are integrated into the existing multi-layer structure of the display panel, combining fingerprint sensing functionality with the display stack. This merging approach reduces overall device complexity compared to adding separate light shielding components.
Solution Approach 2:
The light shielding layers serve multiple functions simultaneously: they shield light to prevent crosstalk, guide light through transmission holes to specific sensors, and maintain structural integrity of the display panel. This multi-functionality reduces the need for additional dedicated components, thereby simplifying the overall device structure while achieving precise fingerprint imaging.
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
The proposed solution effectively reduces or eliminates crosstalk of light reflected from adjacent valleys/ridges, enhancing imaging definition and clarity in fingerprint identification by ensuring that light is collimated and only reaches the intended sensor, suitable for ultrathin display panels.
Implementation Method 1
a light path structure between the photoelectric sensing structure and the second electrode, and configured to collimate light which is on a side of the photoelectric sensing structure distal to the substrate
Implementation Method 2
a photoelectric sensor receives light reflected by valleys or ridges of a fingerprint and generates corresponding electric signals
Data Source
AI summary
A display panel is provided to include a substrate; a photoelectric sensing structure on a side of the substrate; a light emitting structure on a side of the photoelectric sensing structure distal to the substrate, and light emitting elements, each of which includes: a first electrode, a light emitting layer, and a second electrode which are successively in a direction distal to the substrate; and a light path structure between the photoelectric sensing structure and the second electrode, and configured to collimate light on a side of the photoelectric sensing structure distal to the substrate and having a propagation direction towards the photoelectric sensing structure; the photoelectric sensing structure and the light emitting structure do not overlap or partially overlap in a direction perpendicular to the substrate; and the light path structure at least partially overlaps the photoelectric sensing structure in the direction. The embodiment also provides a display device.