Light Emitting Device Recess Scattering Surface Color Uniformity
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Solution Overview
Problem
Conventional light emitting devices face challenges in simultaneously improving color unevenness and light emission output due to the trade-off between the amount of light scattering agent needed to reduce color unevenness and the impact on light absorption and emission efficiency.
Innovation Solution
A light emitting device design where the light emitting element and wavelength converting member are spaced apart from the side surface of the recess portion, allowing direct light extraction from the side surfaces of the light emitting element and incorporating a light scattering surface on the recess portion to scatter and mix light, thereby enhancing light extraction efficiency and suppressing color unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a large amount of light scattering agent is dispersed in the protective adhesive material to suppress color unevenness, then color uniformity is improved, but light emission output decreases due to increased light absorption
Solution Approach 1:
The patent extracts the light scattering function from the protective adhesive material by providing a separate light scattering member with a light scattering surface. This separation allows the protective adhesive material to focus on protection while the dedicated light scattering member handles color uniformity, reducing the amount of scattering agent needed and minimizing light absorption losses.
Solution Approach 2:
The light scattering member acts as an intermediary between the light emitting element and the external environment. It mediates the light extraction process by scattering light in a controlled manner, achieving color uniformity without requiring excessive scattering agents that would absorb light and reduce output.
2Productivity
If the back surface of the light emitting diode chip is directly adhered to the cup portion to increase light extraction, then light emission output is improved, but color unevenness increases due to insufficient light scattering
Solution Approach 1:
The patent segments the light extraction and color mixing functions into separate components: the direct adhesion structure handles light extraction efficiency while the separate light scattering member with light scattering surface handles color uniformity. This segmentation allows each component to optimize its specific function without compromise.
Solution Approach 2:
The light scattering surface is provided on the light scattering member at specific locations where light scattering is needed for color mixing, rather than uniformly throughout the entire protective adhesive material. This localized approach achieves color uniformity with minimal light absorption.
3Productivity
If the light emitting element is placed close to the side surface of the recess portion to maximize light extraction, then light emission output is improved, but color unevenness increases and light returns to the element causing absorption loss
Solution Approach 1:
The patent converts the potentially harmful effect of light traveling toward the side surface into a beneficial scattering opportunity. The light scattering member intercepts light that would otherwise return to the light emitting element or escape inefficiently, scattering it to contribute to color mixing while preventing absorption loss.
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 design improves light extraction efficiency while effectively reducing color unevenness by minimizing absorption loss and scattering of light, allowing for a balanced increase in both light output and color uniformity.
Implementation Method 1
a wavelength converting member disposed in the recess portion between the light emitting element and a top plane of the recess portion and configured to absorb part of light emitted from the light emitting element, convert the absorbed light into light of a different wavelength and emit the converted light
Implementation Method 2
a scattering surface provided on at least a portion of a side surface of the recess portion and configured to scatter the light emitted from the light emitting element and the light emitted from the wavelength converting member
Data Source
AI summary
A light emitting device includes a housing member having a recess open upward, a light emitting element arranged in the recess and having a light emitting layer of a semiconductor, and a wavelength converting member arranged in the recess and capable of absorbing a part of light emission from the light emitting element and emitting light of different wavelength. The light emitting device is capable of mixing the light emission from the light emitting element and the light emission from the wavelength converting member to emit light from the opening of the recess. A light scattering surface for scattering light emission from the light emitting element and wavelength converting member is formed on at least part of the side surface of the recess. The light emitting element and the wavelength converting member are spaced apart from the side and bottom surfaces of the recess, and the side surfaces of the light emitting element are exposed without being covered with the wavelength converting member.