Backlight Unit Light Diffusion Patterns for Uniform White Light
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Solution Overview
Problem
The challenge is to create a backlight unit that can uniformly supply white light without increasing the number of light sources, while also improving color conversion efficiency, which is hindered by the close proximity of color conversion phosphors in liquid crystal display devices, leading to reduced light emission and increased manufacturing costs.
Innovation Solution
A backlight unit design featuring a printed circuit substrate with light sources, a reflective layer, a color conversion light guide layer, a non-color conversion light guide layer, and light diffusion patterns on a transparent film, which allows for efficient light distribution and conversion, reducing the need for additional light sources and enhancing color conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the number of light sources is increased to uniformly emit white light, then the uniformity of light emission is improved, but the cost of parts increases
Solution Approach 1:
A light diffusion film is introduced as an intermediary component between the light sources and the color conversion phosphors. This diffusion film spreads the light from each individual source more widely, allowing fewer light sources to achieve uniform illumination across the backlight unit. The diffusion film acts as a mediator that transforms concentrated light from discrete sources into distributed uniform light.
Solution Approach 2:
The patent applies local quality by positioning light diffusion patterns at specific locations (on the light diffusion film or transparent film) corresponding to each light source. These localized diffusion patterns create targeted light spreading zones that optimize overall uniformity without requiring additional light sources throughout the entire backlight unit.
2Length of stationary object
If color conversion phosphors are placed close together to convert wavelengths, then the thickness is reduced, but some phosphors are obscured by other phosphors reducing color conversion efficiency
Solution Approach 1:
The light diffusion film serves as a mediator between the light sources and the closely-spaced color conversion phosphors. By diffusing the light before it reaches the phosphors, the film ensures that light from each source spreads out and illuminates multiple phosphors effectively, preventing obscuration effects and maintaining high color conversion efficiency even when phosphors are densely packed.
Solution Approach 2:
The patent addresses the phosphor obscuration problem by introducing a new dimension - the light diffusion film positioned in the optical path between light sources and phosphors. This additional layer in the vertical dimension enables light to spread horizontally across the phosphor array, ensuring that closely-spaced phosphors all receive adequate illumination without being obscured by neighboring phosphors.
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 configuration enables uniform white light emission and improved color conversion efficiency, reducing manufacturing costs by minimizing the number of light sources required and optimizing light distribution, resulting in a thinner and more efficient backlight unit.
Implementation Method 1
a plurality of light diffusion patterns disposed on at least one of the top or bottom of the transparent film and corresponding to each of the plurality of light sources
Implementation Method 2
a color conversion light guide layer disposed on the plurality of light sources
Implementation Method 3
a reflective layer disposed on at least a partial area of an area in which the plurality of light sources are not disposed on the printed circuit substrate
Data Source
AI summary
A backlight unit and a display device in which the amount of light emitted to the top surface of the backlight unit is increased, are provided. The backlight unit includes light sources disposed on a printed circuit substrate, a reflective layer disposed on at least a partial area of an area in which the plurality of light sources are not disposed on the printed circuit substrate, a color conversion light guide layer disposed on the light sources, a non-color conversion light guide layer disposed on a surface of the color conversion light guide layer, a transparent film disposed on the color conversion light guide layer and the non-color conversion light guide layer and spaced apart from the light sources and the reflective layer, and light diffusion patterns disposed on a surface of the transparent film and corresponding to each light source.