Area Light Source Device Refractive Index Matching for Contrast
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Solution Overview
Problem
Existing reflective and transmissive liquid crystal display devices suffer from low contrast due to high reflection rates at air gaps in front light sources, leading to decreased brightness and compromised viewing experience in dark environments.
Innovation Solution
An area light source device with a light guide body, structural layers, and second medium layers with specific refractive indices is designed to reduce interface reflection by refractive index matching, improving contrast and brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a front light source with air gap structure is used, then light transparency is improved, but interface reflection increases causing low contrast
Solution Approach 1:
The patent introduces a refractive index matching layer as an intermediary substance between the light guide plate and the trapezoidal structure. This layer has a refractive index that gradually transitions from the light guide plate material to air, reducing the abrupt refractive index difference at interfaces. The matching layer acts as a mediator that allows light to pass through while minimizing reflection at each interface, thereby maintaining high transparency while reducing harmful interface reflections to improve contrast.
Solution Approach 2:
The patent changes the refractive index parameter of the material in the light guide structure by introducing a matching layer with intermediate refractive index properties. Instead of using a single material with fixed refractive index, the system uses multiple layers with progressively changing refractive indices to match the transition from the light guide plate to air. This parameter change approach reduces the abrupt optical property changes that cause reflection, thereby improving contrast while maintaining transparency.
2Ease of operation
If multiple layers of interfaces are created in light guide film, then light guidance function is achieved, but reflection rate increases reducing contrast
Solution Approach 1:
The patent applies refractive index matching layers at each interface between different optical components. These intermediary layers are positioned at the boundaries where light guidance occurs, such as between the light guide plate and the trapezoidal structure. By providing a gradual refractive index transition at each interface, the matching layers enable the light guidance function to work effectively while minimizing reflection losses at each interface, thus maintaining high contrast despite the presence of multiple layers.
3Object-generated harmful factors
If refractive index matching is implemented, then contrast is improved, but device structure becomes more complex
Solution Approach 1:
The patent implements refractive index matching locally only at the critical interfaces where reflection problems occur, rather than throughout the entire device. The matching layers are strategically positioned at specific boundaries between optical components (light guide plate, trapezoidal structure, and air interface) where refractive index transitions cause reflection. This localized approach achieves contrast improvement at the problem areas while keeping the rest of the device structure simple and manageable.
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 significantly enhances the contrast and visual effect of front light sources by minimizing light leakage through refractive index matching, resulting in improved brightness and viewing experience.
Implementation Method 1
the refractive index of a material of the structural layer being greater than the refractive index of a material of the second medium layers
Implementation Method 2
when emitted to the side face of the inverted trapezoidal structure, light will be diverged and totally reflected out from the bottom surface of the trapezoidal structure
Data Source
AI summary
The invention discloses an area light source device comprises: a light guide body comprising an incidence plane, a front exit plane and a rear exit plane which extend along two opposite sides of the incidence plane; a light emitting body disposed along a side of the incidence plane of the light guide body; a structural layer disposed on one side of the rear exit plane, and used for changing the direction of light from the light guide body to the structural layer and emitting the light in a direction away from the rear exit plane; and second medium layers wrapped in the structural layer, wherein the refractive index of a material of the second medium layers is less than the refractive index of a material of the structural layer. The invention further discloses a flat panel display device.