LED Element Structure for Uniform Current Density in LCD Backlights
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Solution Overview
Problem
Existing LED backlight modules for liquid crystal display panels face challenges in achieving high brightness and uniform current density distribution, leading to reduced emission efficiency as the size of the LED elements increases, and require complex and costly mounting processes for efficient flip-chip mounting.
Innovation Solution
The solution involves creating a large-size LED element structure by connecting multiple small-size unit elements in parallel, maintaining the same current density distribution and emission efficiency, and using a center symmetrical electrode arrangement to ensure uniformity and high brightness, while simplifying the mounting process and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the size of LED element is increased to achieve high brightness, then the emission efficiency is improved, but the current density distribution becomes non-uniform
Solution Approach 1:
The LED element is divided into multiple emission regions (first, second, third, and fourth emission regions) with different electrode configurations. Each region has specifically designed electrode patterns that, when combined, achieve uniform current density distribution across the entire large-size element while maintaining high brightness output.
2Ease of manufacture
If the area of electrodes is increased to facilitate mounting, then the ease of manufacture is improved, but the current density distribution uniformity deteriorates
Solution Approach 1:
Different regions of the LED element have different electrode patterns tailored to their specific requirements. The first and second emission regions have one electrode configuration, while the third and fourth emission regions have another configuration. This local differentiation ensures that each region contributes appropriately to uniform overall current density while maintaining ease of mounting with adequately sized electrodes.
3Productivity
If the LED element size is increased for flip chip mounting, then the mounting yield is improved, but the emission efficiency decreases
Solution Approach 1:
The patent transitions from considering LED elements only in terms of size to incorporating the dimension of regional differentiation. By creating multiple emission regions with specific electrode patterns within a large-size element, the invention achieves both high mounting yield (through adequate size) and high emission efficiency (through optimized current distribution in each region).
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 approach allows for high brightness and efficient emission with reduced consumptive power, maintaining emission efficiency even at larger sizes, and facilitates simplified and high-yield flip-chip mounting with lower costs, improving the reliability and efficiency of the LED unit elements.
Implementation Method 1
a light emitting diode element structure having positive and negative electrodes
Implementation Method 2
a white light source having a blue semiconductor light emitting diode element and a yellow fluorescent substance in combination
Data Source
AI summary
A cold-cathode tube has hitherto been used as a backlight for supplying illumination to a liquid crystal television but recently, light emitting diode pieces have been used for a backlight of a large-size liquid crystal television. For the purpose of improving the emission efficiency, flip chip mounting of the light emitting diode piece is advantageous but the mounting yield is restricted by the piece size, electrode structure and wire pattern structure, facing situations having difficulties in realizing simplified mounting and reduction of costs of members. In a liquid crystal display apparatus having a liquid crystal panel, an optical system and a light source, the light source includes a light emitting element structure having positive and negative electrodes, at least one of them being plural, and wires mounted to the positive and negative electrodes through flip chip mounting by making electrical correspondence to individual regions of the positive and negative electrodes.