Low-Pressure Discharge Lamp Phosphor Particle Size Optimization
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Solution Overview
Problem
Conventional low-pressure discharge lamps require larger amounts of expensive rare earth metals as activators to achieve specified optical properties, leading to higher costs due to the need for smaller phosphor particle sizes that increase the surface area and reduce efficiency.
Innovation Solution
The use of phosphor particles with specific size ranges (0.5 μm to 1.9 μm for red, 0.6 μm to 2.8 μm for green, and 1 μm to 4 μm for blue) allows for a thinner phosphor layer with a constant doping level, reducing the required amount of activators and maintaining specified optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If phosphor particles with smaller grain sizes are used, then the phosphor layer thickness can be reduced, but the quantum efficiency decreases due to increased surface area and shorter path length
Solution Approach 1:
The patent changes the particle size parameter of phosphor particles to a specific range (0.5-1.9 μm for red, 0.6-2.8 μm for green, 1-4 μm for blue) to optimize both layer thickness and quantum efficiency. This parameter optimization allows achieving specified optical properties with thinner layers while maintaining acceptable efficiency through precise control of particle dimensions.
2Length of stationary object
If phosphor particles with smaller grain sizes are used, then the phosphor layer can be made thinner, but the amount of activators (rare earth metals) must be increased to maintain optical properties
Solution Approach 1:
The patent optimizes the particle size parameter within specific ranges to reduce the required amount of activators. By controlling particle size distribution and maintaining constant doping levels, the invention achieves specified optical properties with thinner phosphor layers without increasing activator content, thereby reducing costs.
Solution Approach 2:
The patent uses composite phosphor particles consisting of a core shell structure with a core material and a shell material having different refractive indices. This composite structure enhances light absorption and emission efficiency, allowing reduced activator content while maintaining optical properties in thinner layers.
3Area of moving object
If phosphor particles with smaller grain sizes are used, then the surface area increases leading to more impurity accumulation, but this is generally considered detrimental to efficiency
Solution Approach 1:
The patent specifies precise particle size ranges (0.5-1.9 μm for red, 0.6-2.8 μm for green, 1-4 μm for blue) to balance surface area and impurity effects. By controlling particle size within these optimized ranges and maintaining constant doping levels, the invention minimizes impurity accumulation while preserving quantum efficiency and optical properties.
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 approach enables the production of low-pressure discharge lamps with efficient quantum efficiency and cost-effectiveness by minimizing the amount of rare earth metals needed while achieving desired color temperature, luminous flux, and luminous efficacy.
Implementation Method 1
The phosphor particles have phosphors or are formed by them. The phosphor particles or the phosphors can have, for example, crystalline host lattices, some of the lattice sites of which are occupied by activators. In other words, the host lattice can be doped with the activators. The activator, i.e. the doping element, determines the color of the light generated. The activators can include, for example, rare earth metals or be formed by these.
Implementation Method 2
The phosphors can generate visible light by excitation with short-wave light up to UV radiation, for example the UV radiation of mercury. The luminous phenomena are based, for example, on fluorescence or phosphorescence.
Implementation Method 3
If the discharge lamp is switched on, an electric current flows through the gas in the coated discharge vessel, so that the mercury is heated, becomes gaseous and in the gaseous state begins to emit electromagnetic radiation, in particular UV radiation
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
In different embodiments, a low-pressure discharge lamp (1) is provided. The low-pressure discharge lamp has a discharge vessel (2) and a coating structure (7). The coating structure is formed on an inner face of the discharge vessel (2). The coating structure (7) has first fluorescent particles (34) which have at least one fluorescent substance that emits red light and the average particle size of which ranges from 0.5 μm to 1.9 μm, second fluorescent particles (36) which have at least one fluorescent substance that emits green light and the average particle size of which ranges from 0.6 μm to 2.8 μm or from 1 μm to 4 μm, and third fluorescent particles (38) which have at least one fluorescent substance that emits blue light and the average particle size of which ranges from 1 μm to 4 μm.