Graded Index Birefringent Component for Autostereoscopic Displays
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Solution Overview
Problem
Existing surface relief birefringent elements face challenges such as non-uniform filling, increased thickness, high costs, and reduced optical quality due to substrate thickness, delamination issues, and limited optical power, especially in autostereoscopic displays.
Innovation Solution
A graded index birefringent component is created with a liquid crystal layer having self-aligned lens segments, achieved through a manufacturing process involving a surface relief element with sags and a spatially varying electric field applied to the curable liquid crystal material, allowing for intimate contact with the surface relief element and increased optical power without additional mechanical alignment or substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a liquid crystal cell filling method is used with alignment layers and substrates, then birefringent elements can be formed, but the overall thickness increases and substrate removal risks cracking
Solution Approach 1:
The invention extracts and removes the substrate from the final device structure. The liquid crystal layer is cured while supported by the substrate, then the substrate is removed, leaving only the thin liquid crystal layer with the required birefringent properties. This eliminates the thickness contribution of substrates (typically 0.4mm or greater) while maintaining structural integrity during the curing process through proper adhesion design.
Solution Approach 2:
The invention performs preliminary actions by forming the liquid crystal layer and curing it while supported by the substrate before final assembly. The substrate provides mechanical support during the vulnerable curing stage, and preliminary adhesion treatments ensure the liquid crystal layer remains intact. After curing, the substrate can be safely removed since the liquid crystal layer has already gained structural strength.
2Ease of manufacture
If capillary filling is used along the length of cylindrical lenses, then filling can occur, but blockage creates bubbles that degrade optical performance
Solution Approach 1:
The invention replaces the capillary filling mechanism with a coating process. Instead of relying on capillary action to draw liquid crystal material through lens structures (which is prone to blockage and bubble formation), the material is applied as a coating that is then cured. This substitution eliminates the filling uniformity issues while maintaining ease of manufacture, as coating processes are well-controlled and less susceptible to blockage.
Solution Approach 2:
The invention changes the physical state and application method of the liquid crystal material. Rather than attempting to fill pre-formed lens structures through capillary action, the liquid crystal material is applied in a coating state and then cured in place. This parameter change from filling to coating fundamentally avoids the bubble formation problem while achieving the same functional result.
3Ease of manufacture
If a larger spacer gap is incorporated to achieve filling, then filling can be achieved, but more material is used increasing cost and thickness uniformity becomes difficult to maintain
Solution Approach 1:
The invention replaces the spacer-gap-based filling approach with a direct coating process. Instead of incorporating larger spacers to enable filling (which increases material usage and cost), the liquid crystal material is applied directly as a coating and cured. This eliminates the need for additional spacer material while maintaining ease of manufacture, as the coating process naturally achieves uniform coverage without requiring excessive material or complex spacer structures.
4Reliability
If alignment layers are added to both substrates, then liquid crystal alignment is improved, but cost increases and delamination reliability decreases
Solution Approach 1:
The invention extracts and eliminates one of the alignment layers from the traditional structure. Instead of having alignment layers on both substrates, the design uses the surface relief structure itself to provide alignment functionality, or uses a single alignment layer in combination with the cured liquid crystal layer's inherent properties. This reduction in the number of layers decreases device complexity and potential delamination interfaces while maintaining adequate alignment performance.
Solution Approach 2:
The invention makes the surface relief structure multi-functional, serving both as the optical element and as the alignment guide for the liquid crystal molecules. The surface relief pattern inherently directs liquid crystal orientation during curing, eliminating the need for a separate alignment layer in some cases. This universal approach reduces the number of components while maintaining alignment 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
This approach minimizes off-axis vignetting, reduces material costs, and enhances optical power while maintaining image quality, allowing for thinner, more cost-effective production of surface relief birefringent elements with improved alignment and reduced risk of premature cure.
Implementation Method 1
applying an electric field across the curable liquid crystal material, wherein the curable liquid crystal material has a plurality of lens segments self aligned with the sags of the surface relief element, and the electric field varies across each lens segment of the curable liquid crystal material
Implementation Method 2
Graded index birefringent component and manufacturing method thereof
Implementation Method 3
curing the curable liquid crystal material to form a liquid crystal layer
Data Source
AI summary
A graded index birefringent component is described and shown with at least one liquid crystal layer having a plurality of lens segments, wherein the orientation of the liquid crystal molecules varies across each lens segment of the liquid crystal layer.