Backlight Unit Integrated Pattern Sheet Hot Spot Reduction
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Solution Overview
Problem
Direct type backlight units in LCD devices suffer from issues like hot spots and reduced display quality due to direct light emission from sources, which affects uniformity and power consumption.
Innovation Solution
A backlight unit design featuring light emitting diode (LED) packages on a circuit board covered by an encapsulation member with an integrated pattern sheet that includes reflective and diffusion patterns, configured to reduce vertical light emission and enhance side reflection, thereby preventing hot spots and improving display quality.
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 uniformity and brightness of light supplied to the liquid crystal panel is improved and local dimming is realized, but mura such as hot spot happens over the light sources and display quality is reduced
Solution Approach 1:
A light shielding member is introduced as an intermediary component positioned between the light sources and the liquid crystal panel. This member includes light shielding patterns that block direct light paths from specific regions of light sources to the panel, preventing hot spot formation while allowing uniform light distribution through reflected and diffused paths.
Solution Approach 2:
The light shielding member implements local quality by having spatially varying light shielding patterns. Different regions of the member have different shielding characteristics - some areas block light completely while others allow partial transmission - to create uniform overall illumination despite the direct positioning of light sources below the panel.
2Device complexity
If side edge type backlight unit is used with light sources located at a side of the light guide plate, then device complexity is reduced, but local dimming cannot be realized and power consumption increases
Solution Approach 1:
The backlight unit is segmented into multiple independently controllable light source regions arranged in a matrix below the liquid crystal panel. This segmentation enables local dimming by allowing individual or grouped control of different LED regions, improving power consumption efficiency while maintaining a relatively simple direct-type structural layout.
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 reduces hot spots and enhances display quality by ensuring uniform light distribution, allowing for local dimming and reducing power consumption while maintaining a thin profile for the LCD device.
Implementation Method 1
a plurality of reflective patterns at a bottom surface of the base layer and respectively corresponding to the plurality of LED packages
Implementation Method 2
a plurality of diffusion patterns at a top surface of the base layer
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 member located on the circuit board and covering the plurality of LED packages, and an integrated pattern sheet on the encapsulation member. The integrated pattern sheet includes a base layer, a plurality of reflective patterns at a bottom surface of the base layer and respectively corresponding to the plurality of LED packages, and a plurality of diffusion patterns at a top surface of the base layer, wherein the reflective patterns are configured with a relational expression of c+(t2−t1)*tan {(sin−1(1/n)}>d<1.8p, where c, t1 and p are a width, a height and a pitch of the LED package, respectively, t2 and n are a height and a refractive index of the encapsulation member, respectively, and d is a width of the reflective pattern.