LED Light Source with Air-Gap Diffuser for Color Uniformity
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Solution Overview
Problem
Conventional white LED devices experience color splits due to insufficient light diffusion, leading to bluish white illumination at the center and yellowish white at the periphery, and combined lenses fail to improve color uniformity around the periphery while compromising light convergence.
Innovation Solution
A light source device featuring a light emitting diode (LED) with a fluorescent substance and a light diffusing layer separated by an air gap, where the diffusing layer has irregular surfaces to equalize color by altering light angles as they enter the focusing lens, improving both light diffusion and convergence efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a sufficient amount of fluorescent material is used to improve light diffusion and reduce color split, then color uniformity is improved, but the balance between blue light and yellow luminescence is disrupted and luminous efficiency decreases
Solution Approach 1:
The invention separates the light diffusion function from the wavelength conversion function by introducing a dedicated light diffusing layer distinct from the fluorescent material layer. This segmentation allows each component to be optimized independently: the fluorescent material converts blue light to yellow with appropriate quantity for efficiency, while the separate diffusing layer handles color uniformity without disrupting the blue-yellow balance.
Solution Approach 2:
The light diffusing layer acts as an intermediary component between the LED chip and the fluorescent material/output. It mediates the light path by diffusing light before it reaches the fluorescent material or exits the device, thereby equalizing color distribution without requiring excess fluorescent material that would upset the spectral balance.
2Stability of the object's composition
If a combined lens is used to improve color split around the center of illumination, then central color uniformity is improved, but color split around the periphery remains unresolved and light convergence is compromised
Solution Approach 1:
The invention divides the optical system into separate functional components: a regular lens for light convergence and a dedicated light diffusing layer for color uniformity across the entire illumination area including periphery. This segmentation allows the lens to maintain its convergence function while the diffusing layer independently addresses color uniformity without the compromises inherent in combined lenses.
Solution Approach 2:
The light diffusing layer provides localized diffusion properties that can be optimized for different regions of the illumination area. It creates uniform color distribution across the entire field including periphery, while allowing the lens to maintain optimal convergence characteristics for the central region without being constrained by uniform diffusion requirements.
3Device complexity
If the light diffusing layer is directly attached to the LED device or lens without an air gap, then structural simplicity is improved, but color equalization effectiveness is reduced due to lack of refractive index difference
Solution Approach 1:
The air gap acts as an intermediary optical element between the light diffusing layer and the LED device or lens. This thin layer of air with refractive index approximately 1.0 creates the necessary refractive index difference at the interfaces, enabling effective light diffusion and color equalization. The air gap is a simple structural addition that provides significant optical functionality.
Solution Approach 2:
The invention utilizes the refractive index parameter by introducing an air gap with refractive index ~1.0 between the light diffusing layer (refractive index >1.0) and the adjacent components. This parameter change at the interfaces creates the optical conditions necessary for effective light diffusion and color equalization, transforming the optical behavior at the boundaries.
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 achieves well-equalized illumination with high luminous efficiency by diffusing light in two steps through the diffusing layer, reducing color splits and enhancing light extraction and incident efficiency, while maintaining good transmittance.
Implementation Method 1
a light diffusing layer is located between the LED device and the lens... so that the air gap, in combination with the surface irregularities, provides the color equalization by changing angles of the entry of the light into the focusing lens
Implementation Method 2
provides the color equalization by changing angles of the entry of the light into the focusing lens in accordance with differences of indices of refraction due to the air gap
Implementation Method 3
a fluorescent substance, which converts a part of the light from the LED chip... The blue light, which is emitted from the blue LED chip, and the yellow luminescence, which is converted and emitted by the fluorescent substance
Data Source
AI summary
A light source device includes a light emitting diode (LED) device, a lens and a light diffusing layer. The LED device includes an LED chip, which emits light, and a fluorescent, which converts a part of the light from the LED chip. The lens is located on a side of a light emitting face of the LED device. The light diffusing layer is located between the LED device and the lens. An air layer exists between the light diffusing layer and the LED device or between the light diffusing layer and the lens.