Edge Light Backlight Device Prism Sheet Brightness
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Solution Overview
Problem
Conventional edge light-type backlight devices fail to achieve sufficient front side brightness and diffusing property when combined with high refractive index prism sheets due to mismatched emitting angle characteristics between the prism sheet and conventional light diffusion sheets.
Innovation Solution
An edge light-type backlight device is designed with a light diffusion sheet that has a peak emitted light distribution within specific angular ranges (30 to 45° and −30 to −45°) in combination with a high refractive index prism sheet (greater than 1.60), and includes a diffusion layer on a transparent resin film with particles and a back coat layer to optimize light distribution and prevent scratches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a high refractive index prism sheet is used to increase front side brightness, then the front side brightness is improved, but the emitting angle characteristics become mismatched with conventional light diffusion sheets, resulting in insufficient diffusing property
Solution Approach 1:
The patent changes the emitting angle parameters of the light diffusion sheet to match the high refractive index prism sheet. Specifically, the light diffusion sheet is designed to have a peak emitted light distribution in angular ranges of 30 to 45° and −30 to −45° with respect to the normal direction, which corresponds to the emitting angle characteristics of the high refractive index prism sheet. This parameter matching resolves the compatibility issue between the prism sheet and light diffusion sheet.
Solution Approach 2:
The patent creates a composite optical system by combining the high refractive index prism sheet with a specially designed light diffusion sheet. The light diffusion sheet contains a diffusion layer with particles and a back coat layer, forming a composite structure that works synergistically with the prism sheet to achieve both high front side brightness and sufficient diffusing property.
2Device complexity
If conventional light diffusion sheet is used with high refractive index prism sheet, then the device structure remains simple, but the front side brightness and diffusing property are insufficient
Solution Approach 1:
The patent modifies the parameters of the light diffusion sheet, specifically the emitting angle distribution and the diffusion layer composition. The light diffusion sheet is designed with a peak emitted light distribution in 30 to 45° and −30 to −45° angular ranges, and the diffusion layer contains particles with specific size and concentration to achieve the desired optical performance while maintaining structural simplicity.
3Adaptability or versatility
If the light diffusion sheet emits light uniformly in all directions, then the diffusing property is improved, but the front side brightness decreases due to light loss
Solution Approach 1:
The patent applies local quality by designing the light diffusion sheet with directionally controlled emission characteristics. The diffusion layer and back coat layer are configured to emit light preferentially in specific angular ranges (30 to 45° and −30 to −45°) rather than uniformly in all directions. This localized emission optimization ensures that light is directed toward the front side while maintaining sufficient diffusion, thereby preserving front side brightness.
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 enhances front side brightness and diffusing property, reducing electric power consumption and maintaining a balance between brightness and uniformity in liquid crystal display devices.
Implementation Method 1
a light diffusion sheet and a prism sheet successively disposed on a light-emitting surface of the light guide plate
Implementation Method 2
the prism sheet has a refractive index of more than 1.60
Data Source
AI summary
This edge light-type backlight device comprises a light guide plate, a light source disposed at one end part of the light guide plate, a light diffusion sheet and a prism sheet on a light emission face of the light guide plate. The refractive index of the prism sheet exceeds 1.60, a peak of emitted light distribution of the light emission face in a plane parallel to the one end part of the light guide plate and orthogonal to the light emission face is within an angle ranges of 30°˜45° and −30°˜−45° with respect to a normal direction of the light emission face. The emitted light of the light emission face diminishes toward an emission angle −90° or 90° with respect to the normal line from the angle ranges of the peak of the emitted light distribution. High frontal brightness and diffusion are realized.