Double-Sided Backlight Unit with Light-Absorbing Sheet for Uneven Brightness
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Solution Overview
Problem
Double-sided backlight units face challenges with increased cost and brightness unevenness when illuminating liquid crystal display panels of different sizes, as existing solutions require multiple reflective polarizing sheets, which reduce light utilization efficiency and cause illumination inconsistencies.
Innovation Solution
A double-sided backlight unit design featuring a single light guide plate with a light-absorbing sheet and strategically positioned reflective and brightness enhancement films to optimize light distribution, eliminating the need for multiple reflective polarizing sheets and reducing brightness unevenness by using a light-absorbing sheet to manage light impinging on smaller panels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If multiple reflective polarizing sheets are used to illuminate both liquid crystal display panels, then light utilization efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The patent divides the backlight unit into distinct first and second light guide plates, each serving one liquid crystal display panel. This segmentation eliminates the need for multiple reflective polarizing sheets in a single shared light guide plate, reducing device complexity while maintaining efficient light utilization for each panel.
2Device complexity
If a single light guide plate illuminates both liquid crystal display panels, then device complexity is reduced, but brightness unevenness occurs
Solution Approach 1:
The patent uses separate first and second light guide plates for the first and second liquid crystal display panels respectively. This segmentation ensures that each panel receives uniform and independent illumination, eliminating brightness unevenness that would occur with a shared light guide plate while keeping the overall device complexity manageable.
3Use of energy by moving object
If reflective polarizing sheets are used for both panels, then light utilization efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent separates the illumination systems into independent first and second light guide plates, each with its own polarizing sheet configuration. This segmentation reduces manufacturing precision requirements by eliminating the complex alignment needed between multiple reflective polarizing sheets in a single shared system, while still achieving high light utilization efficiency in each independent unit.
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 light utilization efficiency while maintaining uniform brightness across liquid crystal display panels of varying sizes, reducing costs by minimizing the use of reflective polarizing sheets and maintaining high light distribution efficiency.
Implementation Method 1
a light-absorbing sheet disposed between the light guide plate and the first liquid crystal display panel to absorb light impinging thereon
Implementation Method 2
a reflective polarizing sheet provided between the light guide plate and the second liquid crystal display panel
Data Source
AI summary
A single light guide plate illuminates both first and second liquid crystal display panels opposed to each other, the second liquid crystal display panel having a larger display area than that of the first liquid crystal display panel. A light-absorbing sheet is provided between the light guide plate and the first liquid crystal display panel to absorb light from the light guide plate and has a light-transmitting part aligned with the first liquid crystal display panel in a direction from the light guide plate toward the first liquid crystal display panel to transmit light from the light guide plate to the first liquid crystal display panel. A reflective polarizing sheet is provided between the second liquid crystal display panel and the light guide plate. The light-absorbing sheet eliminates brightness unevenness on the second liquid crystal display panel, which would otherwise occur due to the influence of the first liquid crystal display panel, and the reflective polarizing sheet allows effective utilization of light from the light guide plate.