Backlight Unit Integrated Pattern Sheet Hot Spot Reduction
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Solution Overview
Problem
Direct type backlight units in LCD devices suffer from display quality issues due to hot spots and mura caused by direct light emission from sources, which affects brightness uniformity and power consumption.
Innovation Solution
A backlight unit design featuring light emitting diode (LED) packages on a circuit board with an encapsulation layer and an integrated pattern sheet that includes a base layer with lens patterns and hollow cavity particles, which reduces vertical light emission and prevents hot spots by distributing light laterally, thereby improving display quality and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If direct type backlight unit is used with light sources arranged directly below the liquid crystal panel, then brightness uniformity and local dimming capability are improved, but hot spots and mura occur causing reduced display quality
Solution Approach 1:
The patent introduces an integrated pattern sheet as an intermediary component between the LED light sources and the liquid crystal panel. This sheet includes lens patterns that redirect vertically emitted light at specific angles and hollow cavity particles that diffuse light, thereby mediating the direct light path and preventing hot spots while maintaining brightness uniformity
Solution Approach 2:
The integrated pattern sheet applies different optical structures at different locations: lens patterns are positioned corresponding to each LED package to control vertical light emission, while hollow cavity particles are positioned in regions between LED packages to fill in light gaps. This localized differentiation resolves the contradiction by addressing hot spots and uniformity issues specific to different areas
2Ease of manufacture
If side edge type backlight unit is used with light sources at the side, then manufacturing is simplified, but local dimming cannot be realized and brightness uniformity deteriorates
Solution Approach 1:
The patent segments the backlight unit into multiple independently controllable LED packages arranged in a matrix below the liquid crystal panel. Each LED package can be individually driven, enabling local dimming functionality while maintaining a simplified manufacturing process compared to traditional direct type configurations
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 prevents hot spots and enhances display quality by reducing vertical light emission and optimizing light distribution, allowing for a thinner profile and improved contrast ratio while maintaining uniform brightness.
Implementation Method 1
a plurality of lens patterns at a top surface of the base layer and respectively corresponding to the plurality of LED packages
Implementation Method 2
hollow cavity particles at a bottom surface of the base layer and at a region between the plurality of LED packages
Data Source
AI summary
A backlight unit includes: a plurality of light emitting diode (LED) packages on a top surface of a circuit board; an encapsulation layer located on the circuit board and covering the plurality of LED packages; and an integrated pattern sheet on the encapsulation layer, the integrated pattern sheet including: a base layer; a plurality of lens patterns at a top surface of the base layer and respectively corresponding to the plurality of LED packages; and hollow cavity particles at a bottom surface of the base layer and at a region between the plurality of LED packages.