Black Matrix Design for Display Devices to Suppress Diffuse Reflection
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Solution Overview
Problem
Flexible display devices face issues with optical performance deterioration and thickness limitations due to the inclusion of polarizing plates, and the use of color filters to replace them leads to diffuse reflection and rainbow-shaped mura defects.
Innovation Solution
A display device design where the black matrix is entirely exposed without being covered by the color filter, with a thickness greater than the color filter, positioned above it, to suppress diffuse reflection and prevent rainbow-shaped mura by ensuring the color filter does not have a reverse tapered shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a polarizing plate is used to improve display quality and reduce external light reflection, then visibility is improved, but the device thickness increases and flexibility is limited
Solution Approach 1:
The patent removes the polarizing plate from the display device structure and replaces its function with a color filter layer that has light-absorbing properties. This extraction eliminates the thickness constraint while maintaining the light control function, allowing the device to achieve both thinness and flexibility.
2Length of stationary object
If a color filter is used to replace the polarizing plate to reduce device thickness, then device thickness is reduced, but diffuse reflection occurs and rainbow-shaped mura defects appear
Solution Approach 1:
The patent applies different structural characteristics to different regions of the color filter layer. The color filter layer has a tapered structure where the thickness varies from the center to the edges, with the central region having greater thickness than the peripheral regions. This local variation in thickness prevents diffuse reflection and eliminates rainbow-shaped mura while maintaining the overall thin profile of the device.
3Ease of manufacture
If the color filter is formed in a reverse tapered shape to improve manufacturing, then manufacturing is simplified, but diffuse reflection occurs and voids form in the lower portion
Solution Approach 1:
The patent inverts the conventional reverse tapered structure of the color filter layer. Instead of having the peripheral regions thicker than the center, the color filter layer is designed with the central region thicker than the peripheral regions. This inverted tapered structure prevents the formation of voids in the lower portion and eliminates diffuse reflection, while still maintaining manufacturing feasibility.
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 enhances display quality by reducing external light reflection, preventing process defects, and maintaining visibility without the need for a polarizing plate, while allowing for thinner device profiles.
Implementation Method 1
Research is being conducted to improve visibility by omitting the polarizing plate and using a color filter to reduce the reflectance of external light
Implementation Method 2
the black matrix blocks light diffusely reflected from the color filter to prevent rainbow-shaped mura from occurring
Data Source
AI summary
A display device includes a black matrix that is substantially entirely exposed by openings in a color filter in an active area, making it possible to suppress occurrence of diffuse reflection in the color filter.