Variable Light Shielding Black Matrix for OLED Displays
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Solution Overview
Problem
Organic light emitting display devices face challenges with contrast ratio deterioration due to external light reflection, which is not adequately addressed by traditional polarizing plates, leading to limitations in thickness reduction, power consumption, and luminance issues.
Innovation Solution
A display device incorporating a black matrix layer with a variable light shielding unit that changes transmittance based on incident light wavelength, switching between shielding and transmission modes to minimize luminance deterioration and maintain high reflective visibility, while reducing power consumption and thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a polarizing plate is used to reduce external light reflection, then the contrast ratio is improved, but the device thickness increases and power consumption increases
Solution Approach 1:
The patent extracts and removes the polarizing plate from the display device structure, replacing it with a black matrix layer that has light-absorbing properties. This eliminates the need for the thick polarizing plate while still achieving the goal of reducing external light reflection and improving contrast ratio.
Solution Approach 2:
The patent changes the optical parameters of the black matrix layer by controlling its light transmittance to be 40% or less. By adjusting this parameter, the black matrix layer achieves effective light absorption comparable to the polarizing plate, while being much thinner and causing less power consumption increase.
2Object-affected harmful factors
If a polarizing plate is used to reduce external light reflection, then the contrast ratio is improved, but the power consumption increases
Solution Approach 1:
The patent removes the polarizing plate which causes significant power consumption, and replaces it with a black matrix layer that achieves similar or better light absorption with minimal impact on power consumption.
Solution Approach 2:
The black matrix layer serves as a thin, lightweight alternative to the expensive and power-consuming polarizing plate. Although the black matrix layer has limited light transmittance, it achieves the desired light absorption function with much lower energy cost.
3Object-affected harmful factors
If the opening width of the black matrix layer is reduced to improve reflective visibility, then the reflection area is reduced, but the emission area is shielded causing luminance deterioration
Solution Approach 1:
The patent optimizes the light transmittance parameter of the black matrix layer to be 40% or less, which allows for an optimal opening width that balances light absorption and emission. This parameter control ensures that the opening area is sufficient to maintain luminance while the shielding area effectively reduces reflection.
Solution Approach 2:
The patent applies different properties to different areas: the opening area allows light transmission for emission, while the shielding area with controlled light transmittance absorbs external light. This local differentiation optimizes both reflective visibility and 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 effectively reduces external light reflectance and maintains high luminance and color accuracy across various viewing angles, enabling lower voltage operation and extended lifespan without the need for a polarizing plate.
Implementation Method 1
a variable light shielding unit which is adjacent to the opening area and has a light transmittance varying in accordance with a wavelength of incident light
Data Source
AI summary
A display device includes a substrate, a thin film transistor, a first electrode, an organic light emitting layer, a second electrode and a black matrix layer which is includes a shielding area and an opening area. The opening area is formed in a position corresponding to an emission area where light is emitted from the organic light emitting layer and the shielding area includes a variable light shielding unit which is adjacent to the opening area and has a light transmittance varying in accordance with a wavelength of incident light and a light shielding unit with a constant light transmittance.