Backlight Diffusion Plate with Variable Transmissivity Light Blocking Regions
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Solution Overview
Problem
Large-sized liquid crystal display modules face challenges in achieving uniform brightness with high brightness light sources like HCFL, as conventional light curtains are insufficient due to limitations in printing density and light blocking efficiency, leading to brightness irregularities.
Innovation Solution
A liquid crystal display device with a backlight unit that includes a housing, light sources, a diffusion plate with light blocking regions of varying transmissivity, and an intermediate plate, where the light blocking regions are formed by crest-like prisms or reflection patterns to optimize light distribution and uniformity, especially for high brightness HCFL sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If HCFL is used as light source to achieve high brightness, then brightness is improved, but brightness uniformity deteriorates due to insufficient light blocking by conventional dot patterns
Solution Approach 1:
The patent applies local quality by varying the transmissivity of light blocking regions across different areas of the diffusion plate. Specifically, the diffusion plate includes light blocking regions with different transmissivities arranged at different positions, allowing selective control of light transmission in high brightness areas versus low brightness areas. This enables precise local adjustment of brightness distribution to achieve overall uniformity while maintaining high overall brightness from HCFL sources.
Solution Approach 2:
The patent changes the transmissivity parameter of light blocking regions to control light distribution. By adjusting the transmissivity values of different light blocking regions (with at least two different transmissivity values), the system optimizes light blocking efficiency without requiring complete light blockage, thereby maintaining high brightness while achieving uniformity. This parameter variation allows adaptation to the specific characteristics of HCFL light sources.
2Manufacturing precision
If dot pattern light curtain is used to control brightness distribution, then brightness uniformity is improved, but light blocking efficiency deteriorates due to limited printing density
Solution Approach 1:
The patent changes the transmissivity parameter of light blocking regions to optimize light blocking efficiency. By using light blocking regions with at least two different transmissivity values, the system achieves effective light distribution control without requiring complete light blockage. This reduces the stringency of printing density requirements while maintaining brightness uniformity, thereby improving ease of manufacture.
Solution Approach 2:
The patent applies local quality by positioning light blocking regions with different transmissivities at different locations on the diffusion plate. High transmissivity regions are placed where additional light is needed, while low transmissivity regions are placed where light blocking is more effective. This localized optimization achieves brightness uniformity with relaxed printing density constraints.
3Device complexity
If number of fluorescent lamps is reduced for large screen, then device complexity is reduced, but brightness uniformity deteriorates
Solution Approach 1:
The patent applies local quality by implementing light blocking regions with different transmissivities at different positions on the diffusion plate. This allows precise local control of light distribution to compensate for the reduced number of light sources, achieving brightness uniformity even with fewer fluorescent lamps and thus reduced device complexity.
Solution Approach 2:
The diffusion plate acts as an intermediary element between the fluorescent lamps and the display screen. By incorporating light blocking regions with varying transmissivities in the diffusion plate, the system mediates the light distribution from fewer light sources to achieve uniform brightness across the large screen, effectively decoupling the number of lamps from the uniformity requirement.
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 high brightness uniformity across the screen, even with high brightness light sources like HCFL, by strategically arranging light blocking regions and intermediate plates to control transmissivity and illumination distribution, effectively addressing the issue of brightness irregularities.
Implementation Method 1
a diffusion plate which is arranged between the plurality of light sources and the liquid crystal panel, the diffusion plate includes a plurality of light blocking regions at positions corresponding to the plurality of respective light sources
Implementation Method 2
the light blocking region at a center portion of the housing and the light blocking region at an edge portion of the housing exhibit transmissivities different from each other
Data Source
AI summary
A liquid crystal display device having a direct backlight which uses a high-bright light source achieves both of a high efficiency and thin uniformity. In a liquid crystal display device which includes a liquid crystal panel, and a backlight unit which is arranged on a side of the liquid crystal panel opposite to a display screen of the liquid crystal panel, the backlight unit includes a housing, a plurality of light sources arranged in the inside of the housing, and a diffusion plate which is arranged between the plurality of light sources and the liquid crystal panel, the diffusion plate includes a plurality of light blocking regions at positions corresponding to the plurality of respective light sources, and the light blocking region at a center portion of the housing and the light blocking region at an edge portion of the housing exhibits transmissivities different from each other.