Discharge Lamp Cathode Grain Size Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cathode components for discharge lamps with high voltage applications face issues of short service life due to immediate thorium evaporation and uneven emission sites caused by fine thorium dispersion, and the production process is burdened by the need for homogeneous dispersion.
Innovation Solution
A cathode component with a tungsten alloy containing 0.5-3% thorium oxide, where tungsten crystals are regulated in size to 1-80 μm in the circumferential and 10-120 μm in the side cross-section, and thorium component grains are homogeneously dispersed within specific size ranges, enhancing emission characteristics and high-temperature strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If fine thorium dispersion with mean grain size of not more than 0.3 μm is used, then resistance to deformation is improved, but service life is reduced due to immediate evaporation of thorium under high voltage
Solution Approach 1:
The patent changes the grain size parameter of tungsten crystals from fine (≤0.3 μm) to a specific range (1-80 μm in circumferential cross-section, 10-120 μm in side cross-section). This parameter change prevents immediate thorium evaporation under high voltage while maintaining deformation resistance, thereby extending service life.
2Reliability
If fine thorium with mean grain size of not more than 0.3 μm is homogeneously dispersed, then emission characteristics are improved, but production process burden increases
Solution Approach 1:
The patent changes the grain size parameter to 1-80 μm (circumferential) and 10-120 μm (side), which are larger and easier to disperse homogeneously than the previous ≤0.3 μm fine grains. This reduces production process burden while maintaining reliable emission characteristics through controlled grain size distribution.
3Strength
If fine thorium with mean grain size of not more than 0.3 μm is used, then deformation resistance is improved, but heterogeneous dispersion occurs leading to uneven emission sites
Solution Approach 1:
The patent changes the grain size parameter from fine (≤0.3 μm) to a controlled range (1-80 μm circumferential, 10-120 μm side). This larger grain size enables more uniform dispersion throughout the cathode component, creating even emission sites while maintaining adequate deformation resistance through the specified grain size distribution.
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 results in cathode components with excellent emission characteristics and prolonged service life for discharge lamps, even under high voltage conditions, by regulating tungsten grain sizes and ensuring homogeneous thorium dispersion, thereby extending the lifespan while maintaining brightness.
Implementation Method 1
not less than 90% of tungsten crystals are accounted for by tungsten crystals having a grain size in the range of 1 to 80 μm, as observed in terms of an area ratio of 300 μm×300 μm in unit area in a circumferential cross section of the barrel, and not less than 90% of tungsten crystals are accounted for by tungsten crystals having a grain size in the range of 10 to 120 μm, as observed in terms of an area ratio of 300 μm×300 μm in unit area in a side cross section of the barrel
Implementation Method 2
the cathode component comprises a tungsten alloy containing 0.5 to 3% by weight, in terms of oxide (ThO2), of a thorium component
Data Source
AI summary
A highly durable cathode component for a discharge lamp is provided. A cathode component for a discharge lamp includes a barrel having a wire diameter of 2 to 35 mm and a tapered front end, wherein the cathode component comprises a tungsten alloy containing 0.5 to 3% by weight, in terms of oxide (ThO2), of a thorium component, not less than 90% of tungsten crystals are accounted for by tungsten crystals having a grain size in the range of 1 to 80 μm, as observed in terms of an area ratio of 300 μm×300 μm in unit area in a circumferential cross section of the barrel, and are accounted for by tungsten crystals having a grain size in the range of 10 to 120 μm, as observed in terms of an area ratio of 300 μm×300 μm in unit area in a side cross section of the barrel.