Cycloolefin Copolymer Sheet for Curved Displays
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Solution Overview
Problem
Conventional glass front face plates for image display units are difficult to deform into desired curved shapes, leading to inferior formability and operational efficiency, and may deteriorate the quality of liquid crystal cells upon heating, while alternative synthetic resin films face issues with strength and visibility under thermal loads.
Innovation Solution
A flexible sheet for image display units featuring a cycloolefin copolymer substrate layer with an elastomer having a refractive index matching the cycloolefin copolymer, providing improved toughness, flexibility, and moisture resistance, allowing accurate conformation to curved shapes without visibility loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass front face plate is used to increase strength, then strength is improved, but formability and operational efficiency deteriorate due to difficulty in deformation
Solution Approach 1:
The patent replaces the rigid glass front face plate with a flexible resin sheet that can be easily deformed into curved shapes. The resin sheet maintains sufficient strength while enabling flexible formability, directly resolving the contradiction between strength and formability.
Solution Approach 2:
The patent changes the material parameters from glass (rigid, non-flexible) to flexible resin (flexible, deformable). This parameter change enables the front face to be formed into various curved shapes without the manufacturing difficulties associated with glass deformation.
2Ease of manufacture
If glass front face plate is heated to deform into curved shape, then formability is improved, but quality of liquid crystal cell deteriorates due to heat
Solution Approach 1:
The flexible resin sheet can be deformed at lower temperatures compared to glass, reducing the thermal load on the liquid crystal cell. The resin material's inherent flexibility allows deformation without requiring high-temperature heating that would damage the liquid crystal cell.
Solution Approach 2:
The patent converts the potential harm of heat into a benefit by using a resin material that can be deformed at lower temperatures. This eliminates the need for high-temperature heating, thereby protecting the liquid crystal cell from thermal damage while still achieving the desired curved shape.
3Ease of manufacture
If synthetic resin front face film is used to improve formability, then formability is improved, but strength deteriorates when curved
Solution Approach 1:
The patent uses a composite resin sheet structure that combines multiple materials or layers to achieve both flexibility for formability and sufficient strength when curved. The composite structure allows the sheet to maintain its structural integrity while being easily deformable.
Solution Approach 2:
The patent optimizes the resin material parameters including composition, molecular weight, and cross-linking density to achieve the right balance between flexibility and strength. By carefully controlling these parameters, the resin sheet maintains sufficient strength even when curved.
4Strength
If polycarbonate resin front face film is used to improve strength, then strength is improved, but visibility deteriorates due to retardation under thermal load
Solution Approach 1:
The patent changes the resin material from polycarbonate (high photoelastic coefficient) to a resin with lower photoelastic coefficient, reducing retardation under thermal load. This parameter change maintains visibility while preserving strength.
Solution Approach 2:
The patent uses a resin material with homogeneous optical properties that maintain consistent refractive index under thermal conditions, preventing retardation and ensuring stable visibility. The homogeneous structure avoids the optical defects that occur with polycarbonate under thermal stress.
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 cycloolefin copolymer-based sheet effectively conforms to curved screen displays, replacing conventional glass front face plates with enhanced strength, flexibility, and resistance to thermal loads, maintaining image sharpness and preventing dimensional changes.
Implementation Method 1
the substrate layer contains an elastomer having a refractive index substantially equal to a refractive index of the cycloolefin copolymer
Implementation Method 2
the water absorbing property can be kept at a low level, leading to an improvement of moisture resistance of the substrate layer, whereby a dimensional change resulting from bowing, deflection and the like can be prevented
Data Source
AI summary
A sheet for an image display unit to be provided on the front face side of an image display unit includes a substrate layer containing a cycloolefin copolymer as a principal component and an elastomer having a refractive index substantially equal to the refractive index of the cycloolefin copolymer, in an amount of no less than 2 parts by mass and no greater than 7 parts by mass with respect to 100 parts by mass of the cycloolefin copolymer. The substrate layer preferably has an average thickness of no less than 100 μm and no greater than 500 μm, a water absorbing rate preferably no greater than 0.5%, a tensile strength of preferably no less than 40 MPa and no greater than 70 MPa, and a tensile elongation in a longitudinal direction at 25° C. is preferably no less than 4% and no greater than 15%.