Backlight Light Source Arrangement for Display Mura Reduction
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Solution Overview
Problem
Direct type backlight units in LCDs suffer from brightness and color 'Mura' due to non-uniform brightness distribution and color contrast, and the connector configuration on the PCB can further exacerbate these issues.
Innovation Solution
The arrangement of light sources in the backlight unit, where light sources are organized in alternating rows with varying distances and offsets, transitioning from a square pattern along the edges to a triangle pattern in the intermediate region, and the strategic placement of connectors on the PCB to minimize their impact on 'Mura'.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light sources are arranged in a regular grid pattern on the PCB, then manufacturing is simple, but brightness uniformity deteriorates causing Mura effects
Solution Approach 1:
The patent applies asymmetry by arranging light sources in alternating rows where odd-numbered rows and even-numbered rows have different spacing patterns. Specifically, light sources in odd rows are spaced at a first pitch while light sources in even rows are spaced at a second pitch different from the first, creating an asymmetric overall distribution that eliminates regular interference patterns and improves brightness uniformity across the display panel.
Solution Approach 2:
The patent implements local quality by varying the spacing between light sources depending on their position and row number. Different regions of the PCB have different light source densities and arrangements, with intermediate regions having different characteristics compared to edge regions, thereby optimizing brightness distribution locally to prevent Mura effects in different areas of the display.
2Ease of operation
If connectors are placed on the PCB for cable connection, then electrical connection is achieved, but they create shadows affecting brightness uniformity
Solution Approach 1:
The patent extracts the connectors from the main light-emitting area by positioning them in specific regions where they do not interfere with the light path to the display panel. The connectors are placed on the PCB in locations that are either at the edges or in non-interference zones, effectively removing their harmful shadow effect from the critical illumination area while preserving their electrical connection function.
3Illumination intensity
If light sources are densely packed to increase brightness, then illumination intensity improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies dynamics by implementing a non-uniform, adaptive light source arrangement where the pitch between light sources varies by row and position. Rather than using a fixed uniform spacing that would require high precision throughout, the system dynamically adjusts spacing patterns - with larger pitches in certain rows and smaller pitches in others - thereby achieving adequate brightness with relaxed manufacturing tolerances.
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 configuration enhances brightness uniformity, reduces 'Mura' failures, and maintains manufacturing cost-effectiveness by optimizing light source placement and connector positioning.
Implementation Method 1
a direct type backlight unit including white or blue LEDs
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A display device having a structure capable of improving brightness "Mura" and color "Mura" that may be generated in a direct type backlight unit has a structure in which a plurality of light sources are arranged in a pattern similar to a square arrangement along the edges of the backlight unit, and in a pattern similar to a triangle arrangement within an intermediate region of the backlight unit, and a connector for connecting a cable disposed on a Printed Circuit Board (PCB) is disposed on the rear side of the PCB such that the connector does not influence "Mura" of the backlight unit.