Spaced Phosphor Layer for Display Light Source Color Uniformity
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Solution Overview
Problem
Direct-under type light source devices for liquid crystal display devices face issues with color unevenness due to nonuniform phosphor layer application and environmental deterioration, leading to inconsistent light output.
Innovation Solution
A light source device with a color conversion layer spaced apart from the light emitting section, converting part of the light into a different wavelength region, ensuring uniform light path lengths and reducing intensity fluctuations, thereby suppressing color unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a phosphor layer is applied directly on the LED chip surface, then the light output area is compact, but color unevenness occurs due to nonuniform application and environmental deterioration
Solution Approach 1:
The phosphor layer is segmented into multiple separate layers, each applied at different positions and heights above the LED chip. This segmentation allows each phosphor layer to be applied uniformly without the constraints of direct contact with the chip surface, eliminating the nonuniform application problem while maintaining compact overall structure.
Solution Approach 2:
The phosphor layers are positioned at different vertical heights above the LED chip rather than being applied directly on the chip surface. This dimensional separation in the vertical direction allows for uniform phosphor application while maintaining compact horizontal footprint, resolving the contradiction between compactness and uniformity.
2Length of moving object
If the phosphor layer is applied directly on the LED chip, then the light path length is short, but intensity fluctuation occurs due to nonuniform application
Solution Approach 1:
The light conversion function is segmented across multiple phosphor layers at different heights. Each layer contributes to the overall light output, and by distributing the conversion process across multiple levels, the system achieves uniform intensity distribution while maintaining short effective light path lengths through optimized layer positioning.
Solution Approach 2:
Each phosphor layer is positioned at specific local heights above the LED chip where it can uniformly convert light. The local positioning of each phosphor layer ensures consistent light path lengths for all photons passing through the layers, achieving uniform intensity output while maintaining short overall path lengths.
3Device complexity
If a single phosphor layer is used close to the LED chip, then the device structure is simple, but color unevenness occurs due to environmental deterioration
Solution Approach 1:
The single phosphor layer is segmented into multiple separate phosphor layers positioned at different heights. This segmentation provides environmental separation, protecting each phosphor layer from direct exposure to deteriorating conditions while maintaining a relatively simple overall structure. The distributed arrangement reduces stress concentration and improves reliability.
Solution Approach 2:
The spaced arrangement of phosphor layers creates an intermediary space between the LED chip and the phosphor materials. This intermediary positioning protects the phosphor layers from direct environmental deterioration while maintaining effective light conversion, improving reliability without significantly increasing structural complexity.
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 effectively minimizes color unevenness by maintaining uniform intensity across different exit angles, improving the reliability and quality of light output for liquid crystal display devices.
Implementation Method 1
converting part of color light in one wavelength region incident from the light emitting section into color light in another wavelength region, wavelength thereof being longer than that of the one wavelength region
Data Source
AI summary
A light source device capable of suppressing generation of color unevenness, and a display device using the same are provided. The light source device 1 is provided with a plurality of excitation light sources 11 which are arranged at prescribed intervals D on a substrate 10 and emit blue light, and a phosphor layer 12 which converts part of the blue light emitted from the excitation light sources into red light and green light and arranged at a distance from the excitation light sources 11 to oppose the substrate 10. Fluctuation of intensity of each color light due to nonuniform application of the phosphor layer is difficult to occur as compared with a configuration in the past where the phosphor layer is formed adjacent to each excitation light source.