Light Emitting Device Chromaticity Uniformity via Phosphor Segmentation
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Solution Overview
Problem
Light emitting devices with recessed configurations exhibit uneven chromaticity distribution due to phosphor settling and large lateral surface distances, leading to yellowish light emission from lateral surfaces compared to the center.
Innovation Solution
A method involving a light emitting element interposed between light-transmissive members and a sealing member containing phosphor, where the light-transmissive members are strategically positioned to adjust the light path length and chromaticity distribution by cutting along specific paths, allowing for even light emission across the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If phosphor is disposed around the light emitting element to convert original light, then wavelength conversion is achieved, but chromaticity distribution becomes uneven due to phosphor settling
Solution Approach 1:
The phosphor is divided into multiple discrete particles dispersed within the sealing member material rather than forming a continuous layer. This segmentation prevents phosphor settling and maintains uniform chromaticity distribution throughout the sealing member, resolving the contradiction between achieving wavelength conversion and maintaining chromaticity uniformity.
Solution Approach 2:
The sealing member is formulated as a composite material comprising the sealing matrix and dispersed phosphor particles. This composite structure allows the phosphor to remain uniformly distributed within the sealing member while still performing wavelength conversion, eliminating the chromaticity unevenness caused by phosphor settling.
2Area of stationary object
If lateral surface distance is increased in recessed configuration, then light emission area is expanded, but chromaticity uniformity deteriorates due to large distance between light emitting element and lateral surfaces
Solution Approach 1:
The sealing member is designed with non-uniform phosphor distribution characteristics - the phosphor particles are dispersed throughout the entire sealing member volume, creating different local optical properties. This allows the lateral surfaces to emit uniformly chromatic light despite being at large distances from the light emitting element, as each region of the sealing member contributes appropriately to the overall chromaticity.
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
This method adjusts chromaticity distribution, ensuring consistent light emission by optimizing the light path length and phosphor placement, thereby reducing unevenness in light color across the device's surface.
Implementation Method 1
a fluorescent material disposed around the light emitting element so as to convert a part of original light emitted from the light emitting element to light having a different wavelength than that of the original light
Data Source
AI summary
A method for manufacturing a light emitting device includes the steps of: disposing a light emitting element on a base; disposing a single or plurality of light-transmissive members on the base so that the light emitting element is interposed between and spaced apart from at least one pair of opposing portions of the single or plurality of light-transmissive members; covering the base, the at least one pair of opposing portions of the single or plurality of light-transmissive members, and the light emitting element with a sealing member containing a phosphor; and cutting the base, the at least one pair of opposing portions of the single or plurality of light-transmissive members, and the sealing member, along paths on which the at least one pair of opposing portions are disposed.