Optical Assembly Microstructure Bonding for Backlight Uniformity
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Solution Overview
Problem
Current adhesive methods for backlight modules in liquid crystal displays result in poor light uniformity, adhesive force, and thickness issues, along with flaws like curling, waving, and deformation due to heat, which are not effectively addressed by existing technologies.
Innovation Solution
The optical assembly features a diffusing sheet with periodic microstructures bonded to an adhesive layer on a prism sheet, enhancing adhesive force and light diffusion while reducing thickness and heat-related deformations by using microstructures with varying heights and spacings to improve bonding and light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the diffusing sheet is bonded to the prism sheet using conventional adhesive methods, then the total thickness of optical films is reduced, but light uniformity deteriorates
Solution Approach 1:
The diffusing sheet is designed with microstructures having different heights (first microstructures and second microstructures), where each region performs different functions: lower microstructures for light diffusion and higher microstructures for adhesive bonding. This local differentiation resolves the contradiction by maintaining thickness reduction while improving light uniformity through optimized bonding areas.
2Ease of manufacture
If irregular elevating portions are point-bonded to the adhesive layer, then the adhesive process is simplified, but adhesive force deteriorates
Solution Approach 1:
The bonding surface is segmented into multiple discrete microstructures with heights greater than 10 μm, distributed across the diffusing sheet. This segmentation provides numerous localized bonding points that collectively enhance adhesive force while maintaining manufacturing simplicity through the regular periodic pattern of segmented structures.
3Ease of manufacture
If irregular elevating portions are point-bonded to the adhesive layer, then the adhesive process is simplified, but adhesive uniformity deteriorates
Solution Approach 1:
The microstructures exhibit asymmetric height distribution with two distinct levels (first and second microstructures of different heights), creating varied bonding interfaces that improve adhesive uniformity. The asymmetric design ensures consistent bonding performance across the entire adhesive layer while maintaining manufacturing simplicity through periodic patterning.
4Device complexity
If a single optical film is used, then the structure is simplified, but heat resistance deteriorates
Solution Approach 1:
The optical assembly combines multiple optical films (prism sheet and diffusing sheet with microstructures) into a composite structure. This composite design improves heat resistance and prevents deformation while maintaining structural simplicity through the integrated bonding of functional layers with complementary thermal and optical properties.
5Illumination intensity
If the structured surface of the diffusing sheet is bonded to the adhesive layer, then light diffusion is improved, but Moiré pattern is generated
Solution Approach 1:
The diffusing sheet employs local quality differentiation with microstructures of varying heights arranged in specific patterns. This local variation in structure optimizes light diffusion in certain regions while controlling the bonding interface in other regions, thereby reducing Moiré pattern generation while maintaining effective light diffusion performance.
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 solution significantly enhances light uniformity, adhesive force, and heat resistance, reducing the overall thickness of the optical films and minimizing deformation, thereby improving the performance and reliability of the backlight module.
Implementation Method 1
an adhesive layer having a second surface and a third surface opposite to the second surface, wherein the second surface of the adhesive layer is disposed on the first surface of the first optical film
Implementation Method 2
the maximum height of the plurality of second microstructures is greater than that of the plurality of first microstructures so as to bond the plurality of second microstructures to the third surface of the adhesive layer
Data Source
AI summary
The present invention discloses an optical assembly used in the backlight module. The optical assembly comprises: a first optical film having a first surface; an adhesive layer having a second surface and a third surface opposite to the second surface, wherein the second surface of the adhesive layer is disposed on the first surface of the first optical film; and a diffusing sheet having a fourth surface comprising a plurality of first microstructures and a plurality of second microstructures, wherein each of the plurality of second microstructures extends along a first direction, wherein the maximum height of the plurality of second microstructures is greater than that of the plurality of first microstructures so as to bond the plurality of second microstructures to the third surface of the adhesive layer.