Optical Element Alignment Film Structure for High Diffraction, Low Haze
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Solution Overview
Problem
Existing optical elements, particularly Pancharatnam-Berry phase optical elements (PBOEs), face issues with low diffraction efficiency and haze due to misalignment during mask exposure, which affects display quality and productivity.
Innovation Solution
The optical element employs a protruded and recessed alignment film structure with non-parallel alignment treatment regions and continuous molecular alignment using a die transfer method, eliminating the need for multiple masks and reducing haze.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mask exposure method is used to produce PBOE, then the optical element can be manufactured, but mask misalignment occurs causing low diffraction efficiency
Solution Approach 1:
The alignment film is divided into multiple alignment treatment regions (first to N-th regions) arranged from the central portion to the end portion. Each region contains protrusions extending in different directions (first direction to N-th direction), where the N-th direction is parallel to the first direction and intermediate directions are not parallel. This segmentation allows independent alignment control in each region, eliminating the need for multiple masks and ensuring precise molecular alignment without misalignment issues.
Solution Approach 2:
The protruded and recessed structure is pre-formed on the alignment film before the optically anisotropic layer is applied. This preliminary structuring of the alignment film with controlled protrusions in different directions establishes the molecular alignment pattern in advance, so that when the optically anisotropic layer is formed, the molecules naturally align along the protrusion directions without requiring subsequent mask exposure steps.
2Manufacturing precision
If multiple masks are used for alignment treatment, then molecular alignment can be achieved, but productivity decreases due to multiple steps
Solution Approach 1:
Multiple alignment treatment regions with different protrusion directions are merged into a single alignment film structure. Instead of using multiple separate masks for different alignment directions, all alignment patterns are integrated into one alignment film with protrusions extending in first direction to N-th direction, allowing simultaneous formation of all alignment regions in a single step, thereby improving productivity.
3Manufacturing precision
If alignment film is exposed to orthogonal polarized UV light rays, then alignment treatment is performed, but haze is generated lowering display quality
Solution Approach 1:
The alignment pattern is pre-established through the protruded and recessed structure of the alignment film itself, rather than through subsequent UV exposure of a flat alignment film. The protrusions physically guide molecular alignment during the formation of the optically anisotropic layer, eliminating the need for orthogonal polarized UV exposure that causes haze, while still achieving the required alignment treatment.
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 approach achieves high diffraction efficiency and reduces haze, enhancing productivity by stabilizing molecular alignment and avoiding orthogonal UV irradiation.
Implementation Method 1
the anisotropic molecules are aligned with their long axes lying along the first direction to the N-th direction
Implementation Method 2
A PBOE includes, for example, an optically anisotropic layer formed from a liquid crystal composition containing liquid crystal molecules
Data Source
AI summary
Provided are an optical element that has a high diffraction efficiency and can reduce or prevent haze, and a method for producing the optical element. The optical element of the present invention includes an alignment film and an optically anisotropic layer provided on the alignment film and containing anisotropic molecules. The alignment film includes first to N-th alignment treatment regions arranged in order from a central portion to an end portion of the alignment film in a plan view. The first to N-th alignment treatment regions respectively include first to N-th protrusions which protrude toward the optically anisotropic layer and respectively extend in first to N-th directions. The first to (N−1)th directions are not parallel to one another. The N-th direction is parallel to the first direction. N is an integer of 3 or greater.