OLED Light-Absorption Filter Valleys for BT.2020 Color Reproduction
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Solution Overview
Problem
OLEDs using color filters suffer from a low color reproduction range due to differences in peak positions and band widths of red, green, and blue lights between OLEDs and LCDs, which reduces the effectiveness of color filters optimized for LCD backlight whites.
Innovation Solution
Incorporating a light-absorption filter layer with specific absorption valleys between 470 nm to 550 nm and 570 nm to 620 nm in OLEDs, allowing for improved light transmission and reducing color mixing regions, thereby enhancing color reproduction and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If color filters optimized for LCD backlight white light are used in OLED, then the device complexity is reduced and manufacturing is simplified, but the color reproduction range deteriorates
Solution Approach 1:
The patent modifies the optical parameters of the filter layer by introducing specific absorption valleys at 470-550nm and 570-620nm wavelength ranges. This parameter change allows the filter to work effectively with OLED's white light spectrum, achieving 80% or more of BT.2020 color reproduction range while maintaining manufacturing simplicity
Solution Approach 2:
The patent creates a composite optical filter structure combining multiple functional layers with different spectral characteristics. The filter layer integrates light absorption properties at specific wavelengths while maintaining overall light transmission, achieving both color accuracy and manufacturing feasibility
2Manufacturing precision
If a light-absorption filter layer with specific absorption valleys is added to improve color reproduction, then the color reproduction range improves, but the device complexity increases
Solution Approach 1:
The patent segments the filter layer into distinct functional regions with different absorption characteristics. By dividing the filter into sections with specific absorption valleys at different wavelength ranges, it achieves complex color reproduction functionality while maintaining a relatively simple overall structure that can be manufactured in one layer
3Device complexity
If color filters are used to produce red, green, and blue lights from white light, then the device structure is simplified, but light efficiency deteriorates due to light absorption
Solution Approach 1:
The patent applies local quality by making the filter layer selectively absorb light only at specific wavelength ranges (470-550nm and 570-620nm) while transmitting other wavelengths. This localized absorption approach removes color mixing regions and improves color purity without significantly reducing overall light efficiency or brightness
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 the color reproduction range of OLEDs, achieving 80% or more of the BT. 2020 standard, maintaining high brightness without significant loss, and reducing moire phenomena and screen distortion.
Implementation Method 1
a first portion of light-absorption filter layer between the OLED and the emission surface in a subset of sub-pixels, where the first portion has a first valley covering at least a wavelength range of 470 nm to 550 nm, and a second valley covering at least a wavelength range of 570 nm to 620 nm
Data Source
AI summary
An organic light emitting diode (OLED) display device includes an OLED with a plurality of sub-pixels. A first portion of light-absorption filter layer is between the OLED and an emission surface at locations corresponding to selected sub-pixel locations. The first portion of light-absorption filter layer includes a first light-absorption dye and a second light-absorption dye such that the first portion has a light transmittance curve that has a first valley between 470 nm and 550 nm and has a second valley between 570 nm and 620 nm. At the selected sub-pixel locations, there is a color filter between the OLED and the light-absorption filter.