Prism Sheet Cavities Reduce Light Loss and Stress
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Solution Overview
Problem
In liquid crystal display (LCD) backlight modules, the solid prism substrate causes significant light loss, resulting in low brightness due to its thickness, and there is a need to enhance the reliability and reduce stress within the module.
Innovation Solution
A prism sheet with a prism substrate featuring cavities and prism microstructures on its light exit surface is introduced, where the cavities can be blind holes, through holes, or hollow structures, designed to reduce light loss and internal stress, improving the module's brightness and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a solid prism substrate is used to converge light and enhance brightness, then the light convergence effect is achieved, but light loss increases and brightness decreases due to the thickness of the substrate
Solution Approach 1:
The patent introduces a porous structure by forming cavities within the prism substrate. These cavities reduce the overall material density and thickness of the substrate while maintaining the light convergence function through the remaining prism microstructures. The porous design allows light to pass through with reduced absorption and scattering losses compared to a solid substrate of equivalent structural complexity.
Solution Approach 2:
The prism substrate is segmented by introducing multiple cavities that divide the continuous solid structure into separated regions. This segmentation reduces the total path length light must travel through the substrate material, thereby reducing cumulative light loss while still providing sufficient prism microstructures to achieve the required light convergence and brightness enhancement.
2Reliability
If a solid prism substrate is used to provide structural support, then mechanical strength is maintained, but internal stress accumulates and reliability decreases under thermal conditions
Solution Approach 1:
The cavity structure creates a porous substrate that can accommodate thermal expansion and contraction more effectively than a solid substrate. The void spaces allow for stress redistribution and relaxation under thermal conditions, preventing crack propagation and maintaining structural integrity at high temperatures, thereby improving reliability.
Solution Approach 2:
The segmented structure with cavities divides the continuous material into separate regions that can independently respond to thermal stress. This segmentation prevents stress concentration in any single location and allows for more uniform stress distribution throughout the substrate, enhancing reliability under thermal loading conditions.
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 design enhances the optical gain of the prism sheet by 8.86%, reducing light loss and improving the module's brightness, while also increasing its high-temperature reliability by dispersing stress through the cavities.
Implementation Method 1
the area light diffused in various directions is converged by prism sheets (including the upper prism sheet and the lower prism sheet), thereby achieving an effect of enhancing brightness
Data Source
AI summary
A prism sheet includes a prism substrate having at least one cavity therein and a plurality of prism microstructures arranged on a light exit surface of the prism substrate.