Micro Lens Array Substrate Stress Distribution via Segmented Gaps
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Solution Overview
Problem
Micro lens array substrates in liquid crystal devices face issues with stress-induced cracking due to thermal expansion differences and light utilization efficiency, particularly when the lens layer is spaced between adjacent lenses, leading to decreased light gathering efficiency and potential lens layer cracks.
Innovation Solution
A micro lens array substrate design with a lens layer that is continuous between adjacent concave portions in certain directions and discontinuous in others, featuring through-holes or groove portions to distribute stress and improve light utilization, while maintaining lens layer integrity through the use of a transparent layer with higher heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the lens layer is made continuous between adjacent lenses to improve light gathering efficiency, then light utilization efficiency is improved, but stress concentration increases causing crack propagation
Solution Approach 1:
The lens layer is divided into multiple independent lens units separated by gaps. Each lens unit corresponds to a pixel region and is isolated from adjacent lens units by intentional gaps, preventing stress propagation while maintaining individual light gathering functionality. This segmentation resolves the contradiction by allowing each lens to efficiently gather light for its pixel while the gaps prevent crack propagation across the entire array.
Solution Approach 2:
The lens layer exhibits different properties in different regions: within each lens unit, the layer is continuous and thick to maximize light gathering efficiency, while between lens units, gaps are introduced to reduce stress concentration. This local variation in structure allows simultaneous optimization of light utilization in pixel regions and stress distribution in inter-pixel regions.
2Reliability
If the lens layer is separated between adjacent lenses to distribute stress and prevent cracking, then lens layer reliability is improved, but light gathering efficiency decreases
Solution Approach 1:
The lens layer is segmented into discrete lens units with controlled gaps between them. The gaps are positioned to align with pixel boundaries, ensuring that stress distribution is optimized while light gathering within each pixel region remains efficient. This segmentation strategy resolves the contradiction by making the gaps invisible to the optical path of each pixel's light.
Solution Approach 2:
The gap structure is designed in the lateral dimension to distribute stress, while the optical functionality is maintained in the vertical dimension through proper lens curvature and positioning. The gaps are positioned such that they do not interfere with the vertical light gathering path of each lens, effectively resolving the contradiction across different spatial dimensions.
3Ease of manufacture
If high temperature heating processing is applied to form TFT elements after micro lens array substrate formation, then device functionality is achieved, but thermal stress causes crack propagation in the lens layer
Solution Approach 1:
The lens layer is segmented into independent units separated by gaps, which act as stress relief zones during high temperature TFT processing. These gaps prevent thermal stress from propagating across the entire lens layer, allowing the TFT formation process to proceed without causing crack propagation in the lens structures.
Solution Approach 2:
The gaps in the lens layer are designed in advance to accommodate and cushion the thermal stress that will occur during subsequent TFT formation processing. This preemptive structural design allows the lens layer to withstand the high temperature heating process without cracking, resolving the contradiction between manufacturability and reliability.
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 effectively alleviates stress on the lens layer, enhances light utilization efficiency, and suppresses lens layer cracking, resulting in a high-quality, bright liquid crystal display with improved durability and performance.
Implementation Method 1
a lens layer having optical transparency and having a different refractive index from that of the substrate, which is formed on the one surface of the substrate in such a manner as to fill in the concave portion
Data Source
AI summary
A micro lens array substrate includes a substrate including a plurality of concave portions arranged in a first direction and a second direction intersecting the first direction on one surface of the substrate, and a lens layer having a different refractive index from the substrate. The lens layer is formed on the one surface of the substrate to fill in the plurality of concave portions. The plurality of concave portions is continuous in at least one of the first direction and the second direction and is arranged to have a discontinuous part in the lens layer between two adjacent concave portions in a third direction intersecting the first and second directions. A first depth of a center of one concave portion from the discontinuous part is greater than a second depth of the discontinuous part from a surface of the lens layer.