Sub-Pixel Display Layout for Low-Gray Luminance and Red Emission
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Solution Overview
Problem
Existing light emitting display devices face challenges in precisely controlling luminance of low gray levels and suffer from reliability issues with red light emitting elements, particularly those based on AIGaInP, and inefficiencies with InGaN-based elements limiting high-resolution and increasing power consumption.
Innovation Solution
A display device design incorporating sub-pixels with different types of light emitting elements, including a third-type light emitting element with a lower threshold voltage and a wavelength conversion layer to convert light, combined with color filters to enhance red light emission, thereby improving brightness and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If high-efficiency light emitting elements are used, then power consumption is reduced, but luminance control of low gray levels becomes difficult
Solution Approach 1:
The pixel is divided into multiple sub-pixels with different light emitting elements (first, second, and third types). Each sub-pixel has different luminous efficiency characteristics, allowing the system to segment the luminance control range. By selectively activating different sub-pixels, the patent achieves both low power consumption (using high-efficiency elements) and precise luminance control (using combinations of sub-pixels with different efficiencies).
Solution Approach 2:
Different sub-pixels are assigned different light emitting element types with specific luminous efficiency characteristics. The first sub-pixel uses a first-type element, the second sub-pixel uses a second-type element, and the third sub-pixel uses a third-type element. This local differentiation of quality allows the system to optimize both power consumption and luminance control precision by selecting appropriate sub-pixels for different gray levels.
2Illumination intensity
If AIGaInP-based red light emitting elements are used, then red light emission is achieved, but reliability decreases due to wavelength shifting
Solution Approach 1:
The patent introduces a wavelength conversion layer as an intermediary between the light emitting element and the final red light output. The light emitting element emits light at a stable wavelength (avoiding the reliability issues of AIGaInP), and the wavelength conversion layer converts this light to the desired red wavelength. This intermediary approach decouples the reliability requirement from the emission wavelength requirement.
Solution Approach 2:
Instead of changing the material composition of the light emitting element (which would affect reliability), the patent changes the wavelength parameter through a conversion layer. The light emitting element operates at a stable, fixed wavelength, and the wavelength conversion layer adjusts the output wavelength to achieve red light emission without compromising the stability of the light emitting element.
3Manufacturing precision
If InGaN-based light emitting elements are used, then high resolution is achieved, but luminous efficiency decreases and power consumption increases
Solution Approach 1:
The patent segments the pixel into multiple sub-pixels with different light emitting element types. The first sub-pixel uses a first-type element with high luminous efficiency, the second sub-pixel uses a second-type element, and the third sub-pixel uses a third-type element. This segmentation allows the system to achieve high resolution (through the InGaN-based elements) while maintaining good luminous efficiency (through the combination of different element types with complementary characteristics).
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 design achieves high brightness and improved image quality while reducing power consumption by precisely controlling luminance across various gray levels, addressing the limitations of traditional light emitting elements.
Implementation Method 1
a first wavelength conversion layer, the third sub-pixel being configured to emit light in the red wavelength band
Implementation Method 2
a first sub-pixel including a first first-type light emitting element configured to emit light in a blue wavelength band
Implementation Method 3
a red color filter corresponding to the third sub-pixel and configured to transmit only red light
Data Source
AI summary
A display device includes: a first sub-pixel including a first first-type light emitting element configured to emit light in a blue wavelength band, the first sub-pixel being configured to emit light in the blue wavelength band; a second sub-pixel configured to emit light in a green wavelength band; and a third sub-pixel including a second first-type light emitting element configured to emit light in the blue wavelength band, a third-type light emitting element configured to emit light in a red wavelength band, and a first wavelength conversion layer, the third sub-pixel being configured to emit light in the red wavelength band. A threshold voltage of the third-type light emitting element is lower than a threshold voltage of the second first-type light emitting element.