Light-emitting module with refractive index isolation
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Solution Overview
Problem
Existing direct-lit light-emitting devices for liquid-crystal display devices face challenges in achieving high contrast ratios due to light leakage between illumination regions, which can result in unnatural variance in luminance and require complex drive circuits for image display.
Innovation Solution
A light-emitting module with a light guide plate featuring a grid-shaped groove portion and a first light transmission member with a lower refractive index than the plate, along with a reflective resin layer, to control light emission and reduce leakage between regions, allowing for effective local dimming and improved contrast ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If grooves with reflective layers are provided on the lower surface of the light guide plate to prevent light leakage between illumination regions, then contrast ratio is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the refractive index parameter of the material filling the groove portion to be lower than that of the light guide plate, creating optical isolation through refractive index mismatch rather than using reflective layers. This simplifies the structure while maintaining light leakage prevention functionality.
Solution Approach 2:
The patent extracts the reflective layer from the groove structure, removing the complex multi-layer reflective coating and replacing it with a simple low refractive index material filling. This reduces manufacturing steps and structural complexity while achieving the same optical isolation effect.
2Illumination intensity
If local dimming control is implemented by dividing the light emission surface into multiple illumination regions, then contrast ratio is improved, but drive circuit complexity increases
Solution Approach 1:
The patent segments the light guide plate into multiple independently controllable illumination regions by providing groove portions that optically isolate adjacent regions. This allows local dimming control where each region can be turned on or off independently, improving contrast ratio while the simple groove structure keeps manufacturing relatively straightforward.
3Loss of energy
If grooves are formed on the light guide plate to prevent light leakage, then light extraction efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses refractive index parameter change as the primary mechanism for light isolation. By filling the groove with material having lower refractive index than the light guide plate, optical isolation is achieved through a fundamental optical property difference rather than relying on precise geometric groove dimensions, thereby reducing manufacturing precision requirements.
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 enables natural image display with high contrast ratios by minimizing light leakage and maintaining a continuous luminance change, simplifying the drive circuit requirements and enhancing light extraction efficiency.
Implementation Method 1
a first light transmission member disposed inside the groove portion of the light guide plate, and having a refractive index lower than a refractive index of the light guide plate
Implementation Method 2
a portion of light that is emitted by the light source included in an illumination region and travels toward the inside of other illumination regions adjacent to that illumination region, is reflected at the groove
Data Source
AI summary
A light-emitting module includes: a light guide plate having a first surface on which a plurality of first recesses arranged in rows and columns and a grid-shaped groove portion surrounding each of the plurality of first recesses are provided, and a second surface located on the opposite side from the first surface; a plurality of light-emitting elements each disposed inside a corresponding one of the plurality of first recesses; a first light transmission member disposed inside the groove portion of the light guide plate, and having a refractive index lower than a refractive index of the light guide plate; and a reflective resin layer covering the first surface of the light guide plate and the first light transmission member.