Backlight Edge Blue Light Absorber for LCD Color Uniformity
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Solution Overview
Problem
Backlight systems with downconversion film elements suffer from color non-uniformity at the edges of the viewable area due to insufficient red and green light, primarily caused by the difference in angular distribution of red and green light versus blue light, leading to a blue glow.
Innovation Solution
Incorporating a blue light absorber/red and green light reflector at the edges of the backlight system, such as on the support structure, light guide, or light redirecting film, to balance blue light with red and green light, ensuring a uniform white point across the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a downconversion film element is used to increase color gamut, then color gamut is improved, but color uniformity at the edges deteriorates due to blue light leakage and insufficient red and green light
Solution Approach 1:
The patent applies local quality by implementing a blue light absorber/red and green light reflector specifically at the edge regions of the backlight system, rather than uniformly across the entire system. This localized application addresses the specific problem of color non-uniformity at edges while preserving the color gamut enhancement benefits of the downconversion film in the central viewing area.
Solution Approach 2:
The patent converts the harmful blue light leakage at edges into a beneficial effect by using a blue light absorber that selectively absorbs the excess blue light while reflecting red and green light. This transforms the problematic blue glow into a balanced white light output, improving color uniformity without compromising the overall color gamut.
2Quantity of substance
If blue LEDs are used with downconversion film, then color gamut is enhanced, but blue light dominates at edges causing color non-uniformity
Solution Approach 1:
The patent changes the optical parameters at the edge regions by introducing a blue light absorber/red and green light reflector that modifies the spectral composition of light at edges. This selective absorption and reflection changes the intensity distribution of different wavelengths, reducing blue light dominance while enhancing red and green light components at the edges.
Solution Approach 2:
The patent applies different optical properties to different regions: the central area maintains the downconversion film's color conversion properties for enhanced color gamut, while the edge regions incorporate blue light absorbers to specifically address the blue light dominance problem, creating locally optimized optical characteristics.
3Illumination intensity
If red and green light is insufficient at edges, then color balance is achieved in center, but color uniformity across the display deteriorates
Solution Approach 1:
The patent uses a blue light absorber/red and green light reflector that converts the harmful effect of insufficient red and green light at edges into a beneficial outcome. By reflecting red and green light wavelengths while absorbing blue light, the device creates a balanced spectral composition at edges, effectively generating the missing red and green light components through reflection of light from the downconversion film.
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 improves color uniformity by increasing blue light absorption and reflecting red and green light, reducing blue glow and enhancing the display's color gamut by maintaining a uniform mixture of red, green, and blue light across the viewable area.
Implementation Method 1
using a material that reflects red and green light but that absorbs blue light at the edge of the viewable area of the display
Implementation Method 2
using a material that reflects red and green light but that absorbs blue light at the edge of the viewable area of the display
Implementation Method 3
a downconversion film element that actively converts color. The downconversion sheet may comprise, for example, red and green quantum dots, phosphors, fluorescing dyes
Data Source
AI summary
Methods for improving color uniformity across an LCD backlight unit having a viewable area, a downconversion film element and blue LEDS comprise increasing blue light absorption while reflecting red and green light in at least one edge of the viewable area.