Light Diffusion Plate with Variable Density Layers for Uniform Brightness
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Solution Overview
Problem
The challenge is to achieve uniform brightness across the entire surface of a liquid crystal display panel while maintaining a slim design, as reducing the thickness of the backlight unit leads to non-uniform brightness due to decreased distance between the light source and the light diffusion plate, causing 'mura' issues.
Innovation Solution
A light diffusion plate with multiple light diffusion layers is introduced, featuring a pattern with higher density of light transmitting portions at the edge portion and light reflecting portions at the central portion, which increases the ratio of light transmitting to reflecting portions as distance from the central portion increases, ensuring uniform light distribution and recycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the thickness of the backlight unit is decreased to achieve a slim design, then the display apparatus thickness is reduced, but the distance between the light source and the light diffusion plate is decreased, leading to non-uniform brightness and mura on the display panel
Solution Approach 1:
The patent applies local quality by creating different patterns of light transmitting portions and light reflecting portions at different locations on the light diffusion plate. Specifically, the edge portion has a higher density of light transmitting portions to increase light transmission at the edges, while the central portion has more light reflecting portions to control central light distribution. This spatial variation in optical properties compensates for the non-uniform light distribution caused by the reduced distance between light source and diffusion plate, thereby resolving the mura problem while maintaining slim design.
2Illumination intensity
If the distance between the light source and the light diffusion plate is increased to ensure uniform brightness, then brightness uniformity is improved, but the backlight unit thickness increases, compromising the slim design
Solution Approach 1:
The patent changes the optical parameters of the light diffusion plate by varying the density and distribution of light transmitting portions and light reflecting portions across different regions. By adjusting these structural parameters - specifically making light transmitting portions denser at the edges and light reflecting portions more prevalent in the center - the patent achieves uniform light distribution without needing to increase the distance between light source and diffusion plate, thus maintaining slim design while improving brightness uniformity.
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 ensures uniform brightness and a slim design by effectively diffusing light across the display panel, preventing 'mura' and allowing for a reduced distance between the light source and the light diffusion plate without increasing manufacturing costs or complexity.
Implementation Method 1
The light diffusion plate may be disposed between the display panel and the light source such that light emitted from the light source is diffused and guided to the display panel
Implementation Method 2
The at least one light diffusion layer may further include a plurality of light reflecting portions that may be formed between the plurality of light transmitting portions and filled with white ink
Data Source
AI summary
Provided is a display apparatus includes a display panel, a light source configured to emit light toward the display panel, a light diffusion plate disposed between the display panel and the light source such that light emitted from the light source is diffused and guided to the display panel, and at least one light diffusion layer provided on the light diffusion plate, having a light source corresponding portion corresponding to the light source, and including a plurality of light transmitting portions provided with a higher density at an edge portion of the light source corresponding portion than at a central portion of the light source corresponding portion.