Crystallizable Polymer Phase Difference Film for Curved OLED Displays
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Solution Overview
Problem
The challenge is to create a multilayer film for organic electroluminescent display devices that prevents surface deformation, curling, and ensures favorable adhesion between the barrier layer and phase difference film while maintaining optical properties, especially for curved display surfaces.
Innovation Solution
A multilayer film comprising a phase difference film with a crystallizable polymer A, having a melting point of 250°C or higher, and specific optical properties, where the barrier layer is directly disposed on the phase difference film, and includes a ¼ wave plate and a ½ wave plate with oblique slow axes, and an inorganic barrier layer for enhanced adhesion and optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If a resin substrate film is used instead of glass substrate to reduce weight and thickness, then the display device becomes lighter and thinner, but the barrier layer may deform or curl during formation
Solution Approach 1:
The patent applies parameter changes by carefully controlling the heating temperature during barrier layer formation to remain below the glass transition temperature of the resin substrate. This temperature parameter control prevents the resin from softening and deforming, thereby maintaining surface flatness while still enabling barrier layer deposition on the lightweight resin substrate
Solution Approach 2:
The patent employs beforehand cushioning by pre-heating the resin substrate to a controlled temperature before barrier layer formation, and by designing the barrier layer formation process to occur at temperatures that prevent excessive thermal expansion or deformation of the resin substrate, thus cushioning against potential deformation issues
2Strength
If the barrier layer is formed at high temperature to ensure adhesion, then adhesion improves, but the resin substrate may deform or curl
Solution Approach 1:
The patent changes the temperature parameter of barrier layer formation to occur below the glass transition temperature of the resin substrate. This parameter modification allows adhesion to be achieved through chemical bonding mechanisms at lower temperatures, preventing thermal deformation while maintaining strong adhesion between the barrier layer and resin substrate
Solution Approach 2:
The patent replaces thermal-mechanical adhesion (which would require high temperature and pressure) with chemical adhesion mechanisms that operate at lower temperatures. The barrier layer forms strong chemical bonds with the resin substrate through surface chemistry interactions, substituting mechanical compression-based adhesion with chemical bonding
3Ease of manufacture
If a planar display surface is used, then manufacturing is easier, but curved display surfaces require flexible components that maintain optical properties
Solution Approach 1:
The patent employs flexible thin films by using a resin substrate that can be manufactured in flexible forms. The barrier layer and phase difference film are deposited as thin flexible layers on this substrate, creating a multilayer structure that can bend and conform to curved surfaces while maintaining its optical properties and structural integrity
Solution Approach 2:
The patent applies universality by designing a multilayer film structure that serves multiple functions: it provides barrier protection, maintains optical properties for display, and enables both planar and curved display surface configurations. The same structure adapts to different form factors without requiring separate component designs
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 prevents surface deformation and curling, ensures favorable adhesion, and maintains excellent optical and barrier properties, making it suitable for thin, flexible organic electroluminescent display devices with curved surfaces.
Implementation Method 1
the polymer A has a melting point of 250° C. or higher
Implementation Method 2
the layer of the resin A has an in-plane retardation Re of 108 nm or more and 168 nm or less measured with light having a wavelength of 590 nm at 23° C., and an absolute value of a photoelastic coefficient of 2.0×10−11 Pa−1 or less
Implementation Method 3
a barrier layer for interfering with the transmission of moisture, oxygen, and the like is further disposed thereon
Data Source
AI summary
A multilayer film for an organic electroluminescent display device, the multilayer film including: a phase difference film; and a barrier layer directly disposed on a surface of the phase difference film, wherein the phase difference film includes one or more layers of a resin A as a layer in direct contact with the barrier layer, the resin A includes a crystallizable polymer A having a melting point of 250° C. or higher, and the layer of the resin A has a specific value of in-plane retardation Re measured with light having a wavelength of 590 nm at 23° C., and an absolute value of a photoelastic coefficient of 2.0×10−11 Pa−1 or less; a production method therefor; and use thereof.