OLED Light Control Pattern for Reflective Polarizer Ghosting
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Solution Overview
Problem
OLED display devices face reduced light efficiency and image quality due to external light reflection, which is mitigated by attaching a polarizer but results in decreased contrast ratio and light emission efficiency.
Innovation Solution
An OLED display device with a substrate featuring sub-pixels, driving thin film transistors, light-emitting diodes, a polarizer, and a light control pattern inside the substrate to manage light reflection and extraction, including a reflective polarizer and light control patterns like spherical or donut-shaped designs to enhance light output and reduce ghosting phenomena.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a polarizer is attached to block external light reflection, then contrast ratio is improved, but light emission efficiency decreases to less than half
Solution Approach 1:
The patent converts the harmful reflected light into a beneficial resource by using a reflective polarizer to redirect the light that would otherwise be lost. The reflected light from the polarizer is redirected toward the light-emitting diode, allowing it to be re-emitted and contribute to the display output, thus transforming the energy loss into useful light output
Solution Approach 2:
The patent introduces a light control pattern as an intermediary element between the polarizer and the light-emitting diode. This light control pattern acts as a mediator to redirect and control the path of reflected light, ensuring it reaches the light-emitting diode at appropriate angles for effective re-emission
2Object-affected harmful factors
If a polarizer is attached to suppress external light reflection, then visibility is enhanced, but light efficiency of emitted image data is reduced
Solution Approach 1:
The reflective polarizer converts the energy that would be wasted as reflected light into useful light output by redirecting it back through the light-emitting diode, thereby improving overall light efficiency while maintaining the visibility enhancement benefits of the polarizer
Solution Approach 2:
The patent creates a continuous light path where light emitted by the OLED, reflected by the polarizer, and re-directed through the light control pattern back to the OLED, enabling continuous circulation and utilization of light energy rather than single-pass loss
3Illumination intensity
If reflected light is redirected to improve light extraction efficiency, then luminance increases, but light leakage to adjacent sub-pixels may occur causing blurring
Solution Approach 1:
The light control pattern is designed with specific local geometric features (such as microlens arrays or reflective structures) that are positioned and shaped to redirect light locally and precisely, ensuring that light is directed only to the intended sub-pixel areas and not to adjacent regions, thus preventing blurring while maintaining high luminance
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 solution significantly improves light extraction efficiency and image quality by redirecting and re-emitting reflected light, increasing luminance by up to 135% and minimizing light leakage to adjacent sub-pixels, thus preventing blurring and ghosting effects.
Implementation Method 1
a polarizer at an outer surface of the substrate and including a reflective polarizer
Implementation Method 2
improved light extraction efficiency
Implementation Method 3
a light control pattern inside the substrate and corresponding to the non-emission area
Data Source
AI summary
An organic light-emitting diode display device can include a substrate including first, second and third sub-pixels, each of the first, second and third sub-pixels including an emission area and a non-emission area; a driving thin film transistor in the non-emission area of each of the first, second and third sub-pixels; a light-emitting diode connected to the driving thin film transistor; a polarizer at an outer surface of the substrate, the polarizer including a reflective polarizer; and a light control pattern disposed inside of the substrate and corresponding to the non-emission area, the light control pattern being configured to change a direction of light incident on the light control pattern.