LED Backlight Uniform Brightness via Asymmetric Emission
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Solution Overview
Problem
Liquid crystal display devices using LED backlights face challenges in achieving uniform brightness and managing heat generation, with existing solutions requiring complex optical designs and inadequate heat dissipation.
Innovation Solution
A liquid crystal display device configuration featuring a light guide panel with concave portions for alternating LEDs emitting light in opposite directions, combined with a thermal conductive sheet and simplified current supply, allowing for efficient heat dissipation and uniform brightness without complex optical designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If LEDs are arranged in a line emitting light in one direction, then the optical design is simplified, but uneven brightness occurs in the display
Solution Approach 1:
The patent applies asymmetry by arranging LEDs in alternating directions (some emitting leftward, some rightward) rather than uniform single-direction emission. This asymmetric arrangement pattern compensates for the directional nature of LED light emission, ensuring uniform light distribution across the light guide panel while maintaining a simple linear LED configuration without complex optical components.
2Loss of energy
If a reflective sheet with diffuse and mirror reflection areas is used, then light efficiency is improved, but the optical design becomes complicated
Solution Approach 1:
The patent extracts and removes the complex reflective sheet with its diffuse and mirror reflection areas from the optical system. Instead, it relies on the inherent light-emitting properties of alternately directed LEDs combined with a simple light guide panel, achieving effective light distribution without requiring the complicated reflective sheet structure.
3Volume of moving object
If LEDs are placed close together to reduce device size, then heat dissipation becomes more difficult
Solution Approach 1:
The patent segments the LED arrangement into alternating directional groups (left-emitting and right-emitting LEDs) positioned at different locations along the light guide panel. This segmentation allows heat to be distributed to multiple heat sink positions rather than concentrated in one area, improving heat dissipation efficiency while maintaining a compact overall device structure.
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 configuration achieves uniform brightness and effective heat dissipation, reducing the overall size of the device and enabling area brightness control, while simplifying the optical design and heat management.
Implementation Method 1
The plurality of LEDs emit light parallel to a main surface of the light guide panel. First LEDs of the plurality of LEDs emit light in a first direction. Second LEDs of the plurality of LEDs emit light in a direction opposite to the first direction.
Implementation Method 2
WO 2008/029540 A1 discloses a liquid crystal display device with the features in the preamble of present claim 1.
Implementation Method 3
A reflective sheet part of the optical component includes a diffuse reflection area 41DR having a diffuse reflection function, and a mirror reflection area 41R having a mirror reflection function.
Data Source
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AI summary
The present invention enables a liquid crystal display device using LEDs as a light source to reduce uneven brightness, increase efficiency of heat discharged from the LEDs, and provide area brightness control. The liquid crystal display device includes a liquid crystal display panel and a backlight. The backlight includes a light guide panel and a plurality of LEDs arranged on a line. The light guide panel includes a concave portion extending in a longitudinal direction of the light guide panel. A large number of LEDs are placed in the concave portion of the light guide panel. The plurality of LEDs arranged on a line emit light alternately in opposite directions. This configuration allows for uniform brightness distribution without forming a large number of concave portions in the light guide panel. Further, this configuration also allows for area brightness control by controlling a large number of LEDs by group.