Quantum Dot Display Backlight Using UV and Blue Light Segmentation
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Solution Overview
Problem
Current display devices face a trade-off between achieving desired brightness and color gamut coverage, with significant loss in brightness required to achieve wide color gamut coverage, and suffer from leakage of unconverted light that affects color gamut and image quality.
Innovation Solution
Incorporating a backlight unit with a combination of UV and blue light sources and using quantum dot films with filter elements to convert light and block unconverted portions, optimizing the emission and absorption spectra to enhance color gamut coverage and quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a color down conversion layer with high density of nanostructures is used to achieve wide color gamut coverage, then color gamut coverage is improved, but brightness is significantly reduced due to light energy loss from filtering and quenching effects
Solution Approach 1:
The invention segments the color down conversion function by using separate conversion layers for different wavelength ranges. Specifically, it divides the conversion into multiple stages: first converting blue light to green light, then converting remaining blue light to red light. This segmentation allows each layer to operate at lower nanostructure densities, reducing quenching effects while maintaining overall color gamut coverage.
Solution Approach 2:
The invention introduces an intermediary green light conversion step between blue light and red light conversion. The green light acts as an intermediary that absorbs portion of the blue light spectrum, reducing the burden on the red conversion layer and improving overall conversion efficiency. This intermediary step prevents direct competition for blue light absorption between green and red converters.
2Loss of energy
If the density of nanostructures in the color down conversion layer is increased to improve conversion efficiency, then quantum yield is improved, but quenching of optical properties occurs due to close packing of nanostructures
Solution Approach 1:
The invention divides the high-density nanostructure requirement into multiple lower-density layers. Each layer handles a specific portion of the spectrum conversion, allowing nanostructures to be spaced further apart within each layer, thereby reducing quenching effects while collectively achieving high overall conversion efficiency.
3Illumination intensity
If blue light sources with high radiance are used to achieve desired brightness, then brightness is improved, but leakage of unconverted blue light increases affecting color gamut coverage
Solution Approach 1:
The invention segments the blue light absorption function across multiple conversion layers with different spectral responses. The green conversion layer absorbs a portion of blue light, while the red conversion layer absorbs the remaining blue light. This segmentation ensures thorough absorption of blue light across the entire spectrum, preventing leakage while maintaining brightness.
Solution Approach 2:
The invention creates a continuous absorption spectrum for blue light by combining multiple conversion layers that collectively cover the entire blue light range. The green conversion layer handles the longer wavelength blue light, while the red conversion layer handles the shorter wavelength blue light, ensuring continuous and complete absorption without gaps.
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 approach improves color gamut coverage and reduces unwanted light leakage, allowing for better image quality and color balancing while maintaining brightness levels, particularly in achieving wide color gamut standards like Rec. 2020.
Implementation Method 1
The first phosphor film receives light from the plurality of light sources and converts a portion of the received light to emit a secondary light having a third peak emission wavelength
Data Source
AI summary
Embodiments of a display device are described. The display device includes a first sub-pixel with a first quantum dot (QD) film and a first filter element. The QD film receives both UV light and blue light and converts a portion of the received light to emit a secondary light different from the UV and blue light. The filter element is disposed on the quantum dot film and allows the secondary light to pass through the filter element, and the filter element blocks an unconverted portion of the received light from passing through the filter element. The second sub-pixel has a second filter element that allows blue light to pass through the second filter element, and the second filter element blocks the UV light from passing through the second filter element.