Single-Layer Optical-Diffusion Film for Reflective Displays
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Solution Overview
Problem
Existing reflective display devices face challenges in efficiently diffusing external light from a wide range of angles due to the complexity and economic disadvantages of multi-layered optical-diffusion films, leading to issues like blurring and physical problems such as delamination and warpage.
Innovation Solution
A single-layered optical-diffusion film formed by photocuring a composition of polymerizable compounds with different refractive indices, having a film thickness of 60 to 700 μm, and varying incident angles from -70° to 70°, which efficiently diffuses external light with a haze value of 70% or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-layered optical-diffusion films are used to control emission angle, then optical-diffusion performance is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines multiple optical-diffusion film layers into a single integrated film with a specific internal structure. The film contains a transparent resin matrix with dispersed transparent particles having different refractive indices, creating multiple scattering interfaces within one layer rather than requiring multiple separate layers. This merging approach maintains the optical-diffusion performance of multi-layered structures while eliminating the complexity of layering and bonding processes.
Solution Approach 2:
The patent implements a nested structure where transparent particles are dispersed within the transparent resin matrix. The particles are embedded throughout the film thickness, creating internal scattering centers nested within the continuous resin phase. This nested arrangement allows light to interact with multiple refractive index interfaces within a single film layer, achieving the optical effects of multi-layered structures without the physical layering complexity.
2Reliability
If multi-layered optical-diffusion films are used to control emission angle, then optical-diffusion performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines multiple optical-diffusion film layers into a single integrated film with a specific internal structure. The film contains a transparent resin matrix with dispersed transparent particles having different refractive indices, creating multiple scattering interfaces within one layer rather than requiring multiple separate layers. This merging approach maintains the optical-diffusion performance of multi-layered structures while eliminating the complexity of layering and bonding processes.
Solution Approach 2:
The patent changes the fundamental parameter of film structure from multi-layered to single-layered with internal heterogeneity. By dispersing particles with different refractive indices throughout the resin matrix, the patent achieves optical-diffusion performance previously requiring multiple layers, thereby simplifying manufacturing and reducing costs while maintaining emission angle control capabilities.
3Ease of manufacture
If conventional optical-diffusion films are used, then manufacturing is simpler, but emission angle control efficiency deteriorates
Solution Approach 1:
The patent applies local quality by creating regions with different refractive indices within the single film layer. The transparent particles are dispersed throughout the resin matrix, creating localized scattering centers that selectively interact with light at different angles. This local heterogeneity enables precise control of emission angles while maintaining the manufacturing simplicity of a single-layer structure.
Solution Approach 2:
The patent uses a composite material structure consisting of transparent resin and transparent particles with different refractive indices. This composite approach within a single layer creates multiple optical interfaces that control light emission angles, achieving the precision previously requiring multi-layered structures while maintaining manufacturing simplicity.
4Reliability
If internal light source is used in display device, then image display is enabled, but electric power consumption increases
Solution Approach 1:
The patent enables the display device to utilize external light (such as sunlight or ambient light) as its light source through the optical-diffusion film's angle control capabilities. The film redirects incident external light into the display panel at optimal angles, allowing the display to function using environmental light rather than requiring an internal backlight, thereby significantly reducing power consumption while maintaining image display capability.
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 reduces the number of bonding processes, enhances economic viability, and effectively suppresses blurring and delamination, allowing for efficient diffusion and emission of external light as image display light while maintaining stable optical-diffusion characteristics.
Implementation Method 1
a film that is formed by photocuring two or more kinds of polymerizable compounds having different refractive indices while phase-separating the polymerizable compounds, the film having a predetermined internal structure in which regions having a relatively high refractive index and regions having a relatively low refractive index are formed in a predetermined pattern within the film
Implementation Method 2
Known examples of such an optical-diffusion film include a film provided with surface unevenness on the film surface, and a film having fine particles dispersed in the film
Implementation Method 3
a film that is formed by photocuring two or more kinds of polymerizable compounds having different refractive indices while phase-separating the polymerizable compounds
Data Source
AI summary
Provided are an optical-diffusion film for display which, particularly when applied to a reflective display device, can efficiently diffuse and emit an external light incident from a wide range of angles toward the front of the display device as image display light, and a reflective display device using the optical-diffusion film.Disclosed is an optical-diffusion film for display, which is a single-layered optical-diffusion film obtained by photocuring a composition for optical-diffusion film including two or more kinds of polymerizable compounds having different refractive indices, and in which the film thickness of the optical-diffusion film has a value within the range of 60 to 700 μm, and when a coating layer formed by applying a composition for optical-diffusion film in a film form is photocured, and the incident angle of incident light with respect to the normal line of the film plane is varied in the range of −70° to 70° along the travel direction of the coating layer at the time of photocuring, the haze value at each incident angle has a value of 70% or more.