Backlight Module Blue Phosphor Quantum Dot Film Viewing Angle
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Solution Overview
Problem
In quantum dot liquid crystal display panels, the difference in light patterns between red, green, and blue light sources leads to a large yellowish viewing angle due to the slow decay of red and green light and fast decay of blue light as the viewing angle increases, caused by the unique characteristics of quantum dots and light-emitting diodes.
Innovation Solution
A backlight module is developed with a quantum-dot-brightness enhancement film containing a resin system of blue phosphor and red-and-green quantum dots, stimulated by ultraviolet or near-ultraviolet LEDs, which emits red, green, and blue light with the same pattern, and includes a reflective sheet, diffusion plate, and long-wave transmission film to improve light efficiency and filter out harmful ultraviolet light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If blue LED is used as backlight source to stimulate quantum-dot-brightness enhancement film, then blue light pattern becomes small and concentrated, but blue light decays fastly at large viewing angles causing yellowish viewing angle
Solution Approach 1:
The patent introduces a blue phosphor layer as an intermediary between the blue LED and the quantum dot film. The blue phosphor converts part of the blue LED light to blue with a broader emission pattern, which then stimulates the quantum dots. This intermediary approach maintains the concentrated blue light pattern while reducing the decay at large viewing angles, preventing the yellowish viewing angle problem.
2Manufacturing precision
If red and green quantum dots are used with high fluorescence quantum yield, then color purity is improved, but light pattern differences between red, green, and blue become significant causing color deviation at large viewing angles
Solution Approach 1:
The patent applies local quality by making the blue phosphor particles have specific size distributions (0.1-10 micrometers) and placing them in specific locations within the brightness enhancement film. This localized control of phosphor properties creates a blue light component with optimized spatial distribution that compensates for the inherent light pattern differences of the quantum dots, maintaining color consistency across viewing angles while preserving high color purity.
3Manufacturing precision
If quantum dots are used as point light sources, then concentrated luminescence peaks and high color purity are achieved, but light pattern uniformity across different colors deteriorates
Solution Approach 1:
The patent creates a composite brightness enhancement film that combines quantum dots (for high color purity and concentrated luminescence) with blue phosphor particles (for light pattern uniformity). This composite material approach allows the system to simultaneously achieve the benefits of both components: the quantum dots provide high color purity while the blue phosphor provides a broader, more uniform light pattern that stabilizes the overall optical composition across different viewing angles.
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 solution addresses the color deviation issue by ensuring uniform light patterns across viewing angles, enhancing light efficiency through the blue phosphor's diffusion effect and preventing ultraviolet light from passing through the display panel.
Implementation Method 1
the blue phosphor and the red-and-green quantum dots are mixed to prepare a new quantum dot resin system... stimulate the blue phosphor and red-and-green quantum dots jointly emit red, green, and blue light
Implementation Method 2
quantum dot material field is mature and has high fluorescence quantum yield. Taking cadmium selenide (CdSe) quantum dot as an example, its fluorescence quantum yield can reach more than 90%
Implementation Method 3
the blue phosphor can act as diffusion particles to increase the ultraviolet optical path and prevent the agglomeration of the quantum dots
Data Source
AI summary
A backlight module, a display panel, and a display device are disclosed. The backlight module includes a light-emitting diode (LED) light source and a quantum-dot-brightness enhancement film disposed on one side of the LED light source, wherein the quantum-dot-brightness enhancement film contains a resin system of blue phosphor and red-and-green quantum dots.