OLED Display Panel Optical Filtering for Fingerprint Sensors
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Solution Overview
Problem
The integration of a fingerprint recognition function in OLED display screens results in high transmittance of ambient light to the photosensitive element, leading to stray light saturation and increased leakage current, which affects the performance of the fingerprint sensor.
Innovation Solution
Incorporation of a light-blocking element on the optical path of ambient light to reduce transmission to the thin film transistor channel, combined with a filter layer to block specific wavelengths of light, and a photosensitive element positioned to avoid overlap with anode layers to enhance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the photosensitive element is positioned above the OLED backplane for fingerprint recognition, then the fingerprint sensor can be integrated into the display, but ambient light transmits highly to the photosensitive element causing stray light saturation and increased leakage current
Solution Approach 1:
A light-blocking element is introduced as an intermediary component between the ambient light source and the photosensitive element. This element selectively blocks harmful ambient light while allowing the display function to operate normally, thereby resolving the contradiction between fingerprint sensor integration and ambient light interference
Solution Approach 2:
The light-blocking element is positioned specifically at the location where ambient light interferes with the photosensitive element, providing localized light blocking only where needed. This allows the rest of the display to maintain its transparency and display quality while protecting the fingerprint sensor area
2Reliability
If a light-blocking element is added to block ambient light, then stray light saturation is reduced, but the device structure becomes more complex
Solution Approach 1:
The light-blocking element is merged with existing display panel structures or manufactured using the same fabrication processes, combining the light blocking function with the display panel manufacturing without requiring completely separate assembly steps, thus reducing the increase in 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
Reduces stray light saturation and leakage current, improving the sensitivity and accuracy of the fingerprint sensor by blocking ambient light and filtering out unwanted wavelengths.
Implementation Method 1
a light-blocking element located on an optical path of ambient light from outside the display panel transmitted to a thin film transistor channel of the second thin film transistor within the display panel, so as to reduce ambient light transmitted to the thin film transistor channel
Implementation Method 2
the photosensitive element as a fingerprint sensor is located above the OLED backplane and between a plurality of OLED light-emitting pixels
Data Source
AI summary
A display panel and a display device are provided. The display panel includes: a substrate; a driving circuit layer including a plurality of first thin film transistors and a second thin film transistor located on the substrate, wherein the second thin film transistor is located between adjacent first thin film transistors; a plurality of light-emitting elements located on one side of the driving circuit layer away from the substrate, and electrically connected to the plurality of first thin film transistors respectively; a photosensitive element located between adjacent light-emitting elements and electrically connected to the second thin film transistor; and a photoresist element located on an optical path of ambient light transmitted to a thin film transistor channel of the second thin film transistor within the display panel, so as to reduce ambient light transmitted to a thin film transistor channel of the second thin film transistor.