Backlight Unit Light Guide Plate Uniform Brightness
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Solution Overview
Problem
Liquid crystal display devices using direct-type backlight units face issues with non-uniform brightness and appearance due to brightness differences between lamped and un-lamped regions, and the visibility of lamp shapes as 'bright lines', which affect the quality and longevity of the display.
Innovation Solution
A backlight unit design featuring light emitting lamps arranged at regular intervals, a diffusion plate with a transparent substrate and reflection/scattering patterns, and an optical film to ensure uniform light distribution and conceal lamp shapes, improving luminance efficiency and appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a direct-type backlight unit with multiple lamps is used to increase brightness for large-sized displays, then luminance efficiency is improved, but non-uniform brightness and visible bright lines appear due to lamp arrangement
Solution Approach 1:
A light guide plate is introduced as an intermediary component between the lamps and the display panel. The light guide plate receives light from multiple lamps and redistributes it uniformly across the display area, preventing direct visibility of lamps while maintaining high brightness. This mediator transforms concentrated lamp light into diffuse uniform illumination.
Solution Approach 2:
The light guide plate incorporates localized light extraction structures (such as prisms or diffusers) at different positions to control light distribution. These local variations in optical properties ensure that light from multiple lamps is evenly distributed across the entire display area, eliminating bright lines while preserving overall brightness.
2Illumination intensity
If multiple lamps are arranged in a direct-type backlight unit for large displays, then luminance efficiency increases, but the shapes of lamps become visible as bright lines affecting appearance quality
Solution Approach 1:
The light guide plate serves as a mediator that conceals the lamps. Instead of lamps directly illuminating the display panel, light travels through the light guide plate which scatters and redistributes it, making the lamp shapes invisible while maintaining their light output contribution.
Solution Approach 2:
The light guide plate utilizes optical scattering and refraction effects to change the apparent characteristics of light from discrete lamp sources into a continuous uniform illumination field, effectively transforming the visual appearance from distinct bright lines to homogeneous light distribution.
3Device complexity
If lamps are mounted directly at the bottom of the diffusion plate, then device structure is simplified, but brightness uniformity deteriorates due to lamped and un-lamped region differences
Solution Approach 1:
The light guide plate is positioned between the lamps and the diffusion plate, serving as an intermediary that pre-distributes light before it reaches the diffusion plate. This maintains the simple direct-mount structure while the light guide plate ensures uniform light arrival at the diffusion plate, preventing brightness non-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
The solution achieves uniform brightness and enhanced appearance quality by preventing lamp shape visibility, increasing the backlight unit's luminance efficiency and allowing for a slimmed display device structure.
Implementation Method 1
a light control part, having a reflection pattern or a scattering pattern, which is formed at the bottom of the substrate corresponding to the light emitting lamps
Implementation Method 2
a light control part, having a reflection pattern or a scattering pattern, which is formed at the bottom of the substrate corresponding to the light emitting lamps
Implementation Method 3
lens parts which are mounted at the top of the substrate
Implementation Method 4
an optical film which is disposed on the diffusion plate
Data Source
AI summary
A backlight unit for slimmed structure and exhibiting uniform brightness through the improvement of its luminance efficiency and the quality in appearance of which is improved by the removal of bright lines, and a liquid crystal display device having the same are disclosed. The backlight unit includes a plurality of light emitting lamps disposed above a cover bottom such that the light emitting lamps are arranged at regular intervals, a diffusion plate disposed above the light emitting lamps, the diffusion plate including a substrate, a light control part formed on the bottom surface of the substrate corresponding to the light emitting lamps, and lens parts mounted on the top surface of the substrate, and an optical film disposed above the diffusion plate.