Polarizing Plate with Oriented Substrate for Rainbow Suppression
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Solution Overview
Problem
Polyester-based films used in polarizer protection films for image display devices suffer from a rainbow phenomenon due to in-plane birefringence, affecting visibility and mechanical properties, while cellulose ester-based films have high moisture permeability and poor water resistance.
Innovation Solution
A polarizing plate is designed with a polarizer, a first hard coating layer containing a (meth)acrylate-based polymer, a light transmitting substrate with in-plane birefringence and retardation of 3000 nm or more, and a second hard coating layer with solid inorganic nanoparticles, where the acute angle between the slow axis of the substrate and the polarizer's absorption axis is controlled between 5 to 85 degrees, inhibiting the rainbow phenomenon and enhancing mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a polyester-based film is used as the substrate film of a polarizer protection film, then cost is reduced and water resistance is improved, but a rainbow phenomenon is generated due to in-plane birefringence, deteriorating visibility
Solution Approach 1:
The patent changes the orientation angle parameter of the polyester-based film's slow axis relative to the polarizer's absorption axis. By setting this angle to 45 degrees, the in-plane birefringence that causes the rainbow phenomenon is eliminated, while maintaining the cost and water resistance advantages of polyester-based films
Solution Approach 2:
The patent creates a composite structure by laminating the polyester-based substrate film with a polarizer and additional protective films. This composite approach allows the polyester film to provide mechanical strength and water resistance while the overall structure maintains optical performance by controlling the orientation of components
2Strength
If a polyester-based film is used as the substrate film of a polarizer protection film, then mechanical properties are improved, but a rainbow phenomenon is generated, deteriorating visibility
Solution Approach 1:
The patent changes the orientation angle parameter of the polyester-based film's slow axis relative to the polarizer's absorption axis. By setting this angle to 45 degrees, the in-plane birefringence that causes the rainbow phenomenon is eliminated, while maintaining the mechanical properties advantage of polyester-based films
3Illumination intensity
If a cellulose ester-based film is used as the substrate film of a polarizer protection film, then transparency and optical isotropy are improved, but moisture permeability is high and water resistance is poor
Solution Approach 1:
The patent creates a composite structure where the polyester-based substrate film provides water resistance and mechanical strength, while the overall lamination structure maintains optical transparency. The polyester film's inherent water resistance properties protect the polarizer from moisture damage
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 solution effectively suppresses the rainbow phenomenon, improves visibility, and enhances mechanical properties, making the polarizing plate suitable for use as a window or front panel in image display devices, comparable to cellulose ester-based films in terms of visibility and mechanical performance.
Implementation Method 1
a light transmitting substrate positioned on the first hard coating layer, having retardation of 3000 nm or more, and having in-plane birefringence
Implementation Method 2
having retardation of 3000 nm or more, and having in-plane birefringence
Data Source
AI summary
The present invention relates to a polarizing plate including: a polarizer; a first hard coating layer positioned on the polarizer and containing binder resin including (meth) acrylate-based (co) polymer; a light transmitting substrate positioned on the first hard coating layer, having retardation of 3000 nm or more, and having in-plane birefringence; and a second hard coating layer positioned on the light transmitting substrate and including a binder resin, and solid-type inorganic nanoparticles dispersed in the binder resin, wherein the degree of a angle formed by the slow axis of the light transmitting substrate and the absorption axis of the polarizer is 5 to 85°, and an image display device including the same.