Backlight Apparatus Yellow Phosphor Edge Layer Color Uniformity
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Solution Overview
Problem
Existing backlight apparatuses for liquid crystal display devices using blue LEDs and phosphors suffer from color unevenness and thickness issues, leading to suboptimal display quality and difficulty in making the devices sufficiently thin.
Innovation Solution
A backlight apparatus design featuring a light source emitting blue light, a light guide layer with quantum dot phosphor layers on the emitting surface and a reflective layer, and a yellow phosphor layer between the light guide layer and the reflective layer, strategically positioned to address color unevenness and thickness constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a blue LED and green/red phosphors are combined in a remote phosphor type white LED device, then the backlight apparatus can be made thinner, but color unevenness occurs in the display region
Solution Approach 1:
The patent applies local quality by placing a yellow phosphor layer specifically at the outer peripheral portion of the wavelength conversion layer, rather than uniformly distributing phosphors throughout. This localized placement compensates for the blue color dominance at the edges while maintaining the overall thin structure. The yellow phosphor layer has a thickness of 1-10 μm, which is significantly thinner than conventional uniform phosphor layers, yet effectively addresses the color unevenness issue in the peripheral display region.
Solution Approach 2:
The patent utilizes color changes by introducing a yellow phosphor layer that converts blue light to yellow light. This yellow light then mixes with the blue light from the LED and the green/red light from quantum dot phosphors, creating a more balanced white light output. The yellow phosphor's emission spectrum complements the blue LED's spectrum, reducing the blue color dominance and achieving better color uniformity across the display region.
2Manufacturing precision
If a colored layer containing yellow pigment or dye is provided at the outer edge portion of the wavelength conversion layer, then color unevenness is suppressed, but the display device thickness increases
Solution Approach 1:
The patent applies parameter changes by controlling the yellow phosphor layer thickness to be 1-10 μm, which is optimized to provide sufficient yellow light conversion while maintaining thin overall structure. This thickness parameter is significantly reduced compared to conventional colored layers containing pigments or dyes, yet achieves the same color uniformity effect. The thin thickness is made possible by using phosphor materials with high quantum efficiency that can convert blue light to yellow light effectively in a thin layer.
Solution Approach 2:
The patent uses composite materials by combining yellow phosphor particles with a transparent resin to form the yellow phosphor layer. This composite structure allows the layer to be both thin and effective - the phosphor particles provide the color conversion function while the transparent resin matrix maintains optical clarity and structural integrity. The composite material approach enables achieving color uniformity without increasing thickness, as the phosphor-resin composite can be applied in a thin 1-10 μm layer.
3Manufacturing precision
If quantum dot phosphors are used to improve display quality, then color accuracy is enhanced, but the structure becomes more complex
Solution Approach 1:
The patent applies merging by combining multiple phosphor types (yellow phosphor and quantum dot phosphors) into a single integrated wavelength conversion layer structure. The yellow phosphor layer and quantum dot phosphor layer work together in concert, with the yellow phosphor addressing edge color unevenness and the quantum dot phosphors providing accurate color emission in the central display region. This merged structure achieves high color accuracy without requiring separate complex systems for different regions, simplifying the overall device architecture while maintaining performance.
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 suppresses color unevenness and reduces the thickness of the display device while improving display quality by utilizing quantum dot phosphors and a yellow phosphor layer to enhance light emission and distribution.
Implementation Method 1
a blue LED that emits blue light is combined with a green phosphor and a red phosphor... the blue light emitted from the blue LED toward a light guide plate and incident on the light guide plate propagates through the light guide plate, and the blue light emitted from a light emitting surface of the light guide plate is incident on a wavelength conversion layer containing the green phosphor and the red phosphor
Implementation Method 2
a yellow phosphor layer provided between the second main surface of the light guide layer and the reflective layer and in a region along the at least one non-light-receiving side surface... the yellow phosphor layer including a yellow phosphor receiving the blue light and emitting yellow light
Implementation Method 3
a reflective layer disposed on the second main surface side of the light guide layer
Data Source
AI summary
A backlight apparatus includes a light source emitting blue light, a light guide layer, a quantum dot phosphor layer, a reflective layer, and a yellow phosphor layer. The light guide layer includes a first main surface, a second main surface, at least one light-receiving side surface, and at least one non-light-receiving side surface. The quantum dot phosphor layer is provided on the first main surface side of the light guide layer and includes a red quantum dot phosphor and a green quantum dot phosphor. The reflective layer is disposed on the second main surface side of the light guide layer. The yellow phosphor layer is provided between the second main surface and the reflective layer and in a region along the at least one non-light-receiving side surface, and includes a yellow phosphor. The quantum dot phosphor layer is in contact with the first main surface.