Planar Light-Emitting Layout for Uniform White Emission
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Solution Overview
Problem
Planar light-emitting devices often exhibit unevenness in emission color due to differences in peak wavelengths of light-emitting elements, leading to chromaticity variations across the device.
Innovation Solution
A planar light-emitting device configuration with light-emitting elements arranged in a specific pattern, where a first light-emitting element with a lower peak wavelength is positioned in the outer perimeter region and a second light-emitting element with a higher peak wavelength is in the central region, both emitting blue light, and a wavelength conversion member containing phosphors to produce white light, reducing chromaticity differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light-emitting elements with the same peak wavelength are used throughout the device, then manufacturing is simplified, but emission color uniformity deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the peak wavelengths of light-emitting elements based on their spatial location. Elements in the central region use a first peak wavelength (e.g., 445nm) while elements in the peripheral region use a second peak wavelength (e.g., 450nm). This localized differentiation compensates for the non-uniform light distribution pattern, achieving uniform emission color across the entire device while maintaining standardized manufacturing processes.
2Device complexity
If a single type of phosphor is used in the wavelength conversion member, then device complexity is reduced, but emission color uniformity deteriorates
Solution Approach 1:
The patent implements local quality in the phosphor composition by using different phosphor materials or ratios in different regions of the wavelength conversion member. The central region receives phosphor optimized for the first peak wavelength (445nm) while the peripheral region receives phosphor optimized for the second peak wavelength (450nm). This spatially differentiated phosphor distribution ensures uniform color output despite the complexity of managing multiple phosphor types.
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 configuration reduces unevenness in emission color by adjusting the peak wavelengths and using phosphors to achieve consistent white light emission, minimizing the bluish white appearance and enhancing color uniformity.
Implementation Method 1
a wavelength conversion member located above the plurality of light-emitting elements, the wavelength conversion member containing a phosphor that emits light when being excited by light emitted from the plurality of light-emitting elements
Data Source
AI summary
A planar light-emitting device includes a plurality of light-emitting elements arranged at same intervals in a planar configuration, and a wavelength conversion member located above the plurality of light-emitting elements. The plurality of light-emitting elements is configured to emit blue light. The wavelength conversion member contains a phosphor that emits light when being excited by light emitted from the light-emitting elements. The plurality of light-emitting elements includes a first light-emitting element located in an outer perimeter region in a plan view, and a second light-emitting element located in a central region in the plan view. The central region is positioned inward of the outer perimeter region in the plan view. A peak wavelength of light emitted from the first light-emitting element is less than a peak wavelength of light emitted from the second light-emitting element.