Planar Light Source Matrix Pitch Optimization for LCD Uniformity
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Solution Overview
Problem
Existing plane light sources for LCDs require a large number of light emitting devices to achieve uniform brightness, leading to inefficiencies and increased size, weight, and environmental concerns due to the use of CCFLs, while LED-based solutions face challenges in reducing the number of devices needed for uniform luminance.
Innovation Solution
A plane light source with light emitting devices arranged in a matrix configuration, where the pitch between devices is optimized using the equation S≤l2×tan(θ2+α) to ensure uniform luminance distribution, with a diffusion sheet and light collecting sheets to enhance light distribution, reducing the number of devices by 15-25% while maintaining uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a large number of light emitting devices are arranged in a matrix to cover the light emitting area, then uniform brightness is achieved, but the number of devices increases leading to increased size, weight, and complexity
Solution Approach 1:
The patent introduces a third dimension (vertical stacking) by placing a second matrix of light emitting devices above the first matrix, separated by a predetermined distance. This three-dimensional arrangement allows the system to achieve uniform brightness distribution with fewer total devices compared to a traditional two-dimensional planar arrangement, as the vertically stacked matrices create overlapping light fields that fill in brightness variations more efficiently.
Solution Approach 2:
The light emitting device array is segmented into two separate matrices positioned at different vertical levels. Each matrix can be independently designed and optimized, allowing the system to achieve uniform illumination by combining the light output from both segmented matrices rather than requiring a single large two-dimensional array.
2Productivity
If the number of light emitting devices is reduced to improve efficiency, then size and weight are reduced, but the distance between neighboring devices increases causing non-uniform brightness distribution
Solution Approach 1:
By transitioning from a two-dimensional to a three-dimensional arrangement with vertically stacked matrices, the patent maintains uniform brightness distribution even when the horizontal pitch between devices is increased. The vertical separation distance is optimized so that light from the upper matrix fills in the dark regions between devices in the lower matrix, achieving uniform illumination with fewer devices per matrix.
Solution Approach 2:
The patent optimizes the vertical distance parameter between the two matrices and the pitch parameter within each matrix to achieve the desired uniformity of luminance. By carefully selecting these geometric parameters, the system achieves efficient device spacing while maintaining uniform brightness distribution across the light emitting surface.
3Illumination intensity
If CCFLs are used as light sources, then backlight illumination is achieved, but environmental contamination occurs and response speed is slow
Solution Approach 1:
The patent replaces long-lived but environmentally harmful CCFLs with LEDs that have different environmental characteristics. While LEDs have a finite lifespan, they are environmentally friendly, energy-efficient, and can be easily replaced as individual components in the matrix array, making the system more sustainable despite the shorter individual device lifetime.
Solution Approach 2:
The patent substitutes the gas discharge mechanism of CCFLs with the electroluminescence mechanism of LEDs. This replacement eliminates mercury content and associated environmental contamination while providing faster response speeds and better energy efficiency, maintaining the backlight illumination function through a different physical mechanism.
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 achieves significant reductions in the number of light emitting devices, improving efficiency and reducing size and weight, while maintaining uniform luminance distribution across the LCD panel, enhancing environmental sustainability by using LEDs.
Implementation Method 1
a light emitting device matrix including a plurality of light emitting devices arranged in rows and columns at a substrate
Implementation Method 2
a diffusion sheet and light collecting sheets to enhance light distribution
Data Source
AI summary
A plane light source having a plurality of light emitting devices arranged in a light emitting device matrix having rows and columns at a substrate, the plane light source including: a first matrix having a plurality of light emitting devices arranged in rows and columns; and a second matrix having a plurality of light emitting devices arranged in rows and columns, each of the light emitting devices located within a quadrangle formed by four neighboring light emitting devices included in the first matrix, wherein the pitch of the light emitting devices of the first and second matrices is different from each other.