Phase Difference Plate Manufacturing via Sequential Stretching
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Solution Overview
Problem
Existing methods for manufacturing phase difference plates are complex and difficult to scale for broad widths, particularly in liquid crystal display devices, leading to issues with light leakage when viewed from oblique angles.
Innovation Solution
A method involving the formation of a layered body with resin layers having positive and negative intrinsic birefringence, subjected to sequential stretching in different directions at specific temperatures to achieve the required refractive index relationships, allowing for the production of a phase difference plate that compensates for light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a shrink film is adhered to one side or both sides of the resin film and the layered body is stretched under heating, then a phase difference plate with specific refractive index relationship (Nx>Nz>Ny) can be obtained, but the manufacturing process becomes complicated and difficult to scale for broad widths
Solution Approach 1:
The invention extracts and removes the shrink film from the manufacturing process entirely. Instead of using a shrink film to apply constraining force during stretching, the patent directly stretches the resin film between two substrates without any intermediate shrink film layer, thereby simplifying the manufacturing process while maintaining the ability to achieve the desired refractive index relationship.
Solution Approach 2:
The invention segments the manufacturing process into distinct stages: first forming a layered body with specific resin layers, then stretching it between substrates mounted on a stretching device. This segmentation allows for precise control of the stretching process and facilitates production of broad-width phase difference plates without the complexity of shrink film handling.
2Manufacturing precision
If a shrink film method is used to manufacture the phase difference plate, then the refractive index relationship can be achieved, but the phase difference plate cannot be manufactured with broad width
Solution Approach 1:
By removing the shrink film constraint, the invention enables manufacturing of phase difference plates with broad widths. The direct stretching method between substrates eliminates the width limitations imposed by shrink film handling and application, allowing production of large-area display panels.
Solution Approach 2:
The invention transitions from a method constrained by two-dimensional shrink film application to a three-dimensional stretching process between substrates. This dimensional change allows the resin film to be stretched uniformly across broad areas, enabling production of phase difference plates with widths suitable for large displays.
3Manufacturing precision
If a complex manufacturing process with shrink film is used, then the phase difference plate can be produced, but the production cost increases and productivity decreases
Solution Approach 1:
By eliminating the shrink film step, the invention reduces the number of manufacturing steps, decreases production time, and lowers material costs. The direct stretching process requires fewer materials and less handling, thereby improving productivity and reducing production costs while maintaining phase difference plate quality.
Solution Approach 2:
The invention merges the substrate mounting and stretching operations into a single integrated process. The substrates are mounted directly onto the stretching device, and the stretching is performed in one continuous operation, eliminating the separate shrink film application and heating steps, thereby improving production efficiency.
Data Source
AI summary
A step of forming a layered body including a resin layer (a) containing a resin A having positive intrinsic birefringence and a resin layer (b) containing a resin B having negative intrinsic birefringence, the resin layer (b) being provided on one side of the resin layer (a); a first stretching step of stretching the layered body in one direction at a temperature T1; and a second stretching step of, after the first stretching step, stretching the layered body in another direction that is approximately orthogonal to the previous stretching direction at a temperature T2 which is lower than the temperature T1 to obtain a phase difference plate are performed. By these steps, a phase difference plate wherein a slow axis of the resin layer (a) after the stretching treatment and a slow axis of the resin layer (b) after the stretching treatment are approximately parallel to each other, and in-plane retardation Rea and NZ coefficient NZa in the resin layer (a) after the stretching treatment, and in-plane retardation Reb and NZ coefficient NZb in the resin layer (b) after the stretching treatment satisfy specific relationship is obtained.