Light Guide Plate Anisotropic Refraction for Uniform Luminance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing edge-light type surface light source devices experience luminance unevenness due to light leakage through the light entrance surface, leading to emission lines on the light exit surface.
Innovation Solution
A light guide plate is designed with a refractive index Nx perpendicular to the light entrance surface higher than Ny parallel to the light exit surface, and a manufacturing method using an extrusion process forms projections and recesses to guide light uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the light guide plate is manufactured by an extrusion method with conventional isotropic refractive index, then the manufacturing process is simple, but luminance unevenness and emission lines occur due to light leakage
Solution Approach 1:
The patent applies parameter changes by transitioning from an isotropic refractive index to an anisotropic refractive index distribution. Specifically, the light guide plate is designed with different refractive indices in different directions: a higher refractive index in the thickness direction (perpendicular to the light entrance surface) and a lower refractive index in the plane direction (parallel to the light exit surface). This parameter change resolves the technical contradiction by maintaining the simplicity of the extrusion manufacturing method while eliminating luminance unevenness and emission lines through the controlled anisotropic optical properties of the resin material.
2Manufacturing precision
If the refractive index in the thickness direction is increased to suppress light leakage, then luminance uniformity is improved, but the device complexity increases
Solution Approach 1:
The patent resolves this contradiction by changing the optical parameter of the resin material itself rather than modifying the structural complexity. By selecting a resin with anisotropic refractive index properties where the refractive index in the thickness direction (nx) is higher than in the plane direction (ny), the patent achieves improved luminance uniformity without increasing device complexity. The single-layer light guide plate structure maintains simplicity while the material's inherent anisotropic optical parameters provide the necessary light control.
Solution Approach 2:
The patent employs composite material principles by utilizing resin materials with specific anisotropic optical properties. The light guide plate is made from a resin that exhibits different refractive indices in different directions, effectively creating a functionally composite optical material. This approach achieves the desired luminance uniformity through material selection rather than structural complexity, as the anisotropic resin inherently provides the necessary light guidance and emission control.
3Ease of manufacture
If conventional extrusion method is used without orientation control, then the manufacturing process is simple, but projection and recess shapes are not properly formed leading to light guidance issues
Solution Approach 1:
The patent applies preliminary action by preparing the resin material with pre-oriented molecular alignment before the extrusion process. The resin is supplied in a state where its molecular chains are already oriented in a specific direction, which ensures that the projection and recess shapes are properly formed during extrusion. This preliminary orientation of the resin material allows the conventional extrusion method to produce light guide plates with accurate projection and recess structures, resolving the contradiction between manufacturing simplicity and shape accuracy.
Solution Approach 2:
The patent changes the physical state parameters of the resin material during the extrusion process. By controlling the temperature, pressure, and cooling rate parameters during extrusion, the patent ensures that the resin properly forms the projection and recess shapes while maintaining the anisotropic refractive index distribution. The parameter control during extrusion allows the resin to transition from a molten state to a solidified state with the desired optical and structural properties, achieving both manufacturing simplicity and shape accuracy.
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 luminance unevenness by ensuring uniform light emission from the light exit surface, reducing the visibility of emission lines and enhancing display quality.
Implementation Method 1
a refractive index Nx in a direction perpendicular to the light entrance surface is higher than a refractive index Ny in a direction parallel to the light exit surface and parallel to the light entrance surface
Implementation Method 2
the light emitted from the light source enters the light guide plate through the light entrance surface, and travels in a direction (light guide direction) orthogonal to the light entrance surface from the light entrance surface toward the facing surface facing the light entrance surface while repeating the reflection by the light exit surface and the back surface facing the light exit surface
Data Source
AI summary
Provided are a light guide plate, an area light source device, a display device, and manufacturing method for the light guide plate such that the occurrence of uneven luminance is suppressed. The light guide plate is characterized in that the light guide plate has a light entrance surface through which light enters, a light exit surface intersecting with the light entrance surface and through which light is output, and an opposite surface facing the light entrance surface, wherein the light entering through the light entrance surface is guided to the opposite surface side and output from the light exit surface, and the refractive index Nx in a direction perpendicular to the light entrance surface is higher than the refractive index Ny in a direction parallel to the light exit surface and parallel to the light entrance surface.