Short Arc Discharge Lamp Electrode Groove Design
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Solution Overview
Problem
The transition time from glow discharge to arc discharge in short arc type discharge lamps is not sufficiently short, leading to blackening of the arc tube base portion due to electrode material evaporation, which is exacerbated by the miniaturization of projector apparatus and the close proximity of electrodes to the arc tube wall.
Innovation Solution
The design incorporates electrodes with a main body portion, an axis portion, and a taper portion, where the axis portion has a smaller outer diameter than the main body portion, and grooves are formed along the axis or taper portions to facilitate the movement of electric discharge to the tip portion, reducing the time spent in the glow discharge phase and preventing base portion blackening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the transition time from glow discharge to arc discharge is shortened, then electrode material evaporation is reduced, but the electrode structure must be modified to achieve faster heating
Solution Approach 1:
The electrode is divided into three distinct portions: a base portion, a main body portion with grooves, and a tip portion. This segmentation allows each portion to serve a specific function - the grooves in the main body portion facilitate faster heating during glow discharge while maintaining structural integrity through the base portion
Solution Approach 2:
The main body portion of the electrode is equipped with grooves that create localized heating zones during glow discharge. This local quality modification enables preferential heating of specific regions to accelerate the transition to arc discharge without requiring complete structural redesign
2Volume of moving object
If electrodes are positioned close to the arc tube wall for miniaturization, then device size is reduced, but electrode material evaporation causes blackening of the arc tube base portion
Solution Approach 1:
The electrode structure is designed in advance with grooves in the main body portion that promote faster and more uniform heating during the glow discharge phase. This preliminary structural arrangement ensures that the transition to arc discharge occurs more quickly, preventing excessive heating and material evaporation before the arc discharge begins
Solution Approach 2:
The grooves in the electrode main body portion, which could be seen as structural complexity, actually serve to convert the harmful effect of prolonged glow discharge (which causes heating and material evaporation) into a beneficial faster transition to arc discharge, thereby reducing overall material evaporation
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 design effectively shortens the transition time from glow to arc discharge, suppresses electric discharge at the base portion, and prevents arc tube blackening, while also aiding in the movement of mercury into the arc tube and reducing the risk of sealing portion breakage due to internal pressure.
Implementation Method 1
the groove is heated at time of glow discharge due to the hollow effect produced by the groove provided in the main body portion of the electrode
Implementation Method 2
the base portions of the electrodes are heated with arc, so that electrode structure material which is evaporated from the electrode base portions adheres to a wall of the arc tube
Implementation Method 3
During this glow discharge, these electrodes are heated by collisions of cations of rare gas and those of mercury
Implementation Method 4
When these electrodes are heated to the temperature at which thermionic emission becomes possible by the glow discharge, the electric discharge shifts from the glow discharge to arc discharge
Data Source
AI summary
A short arc type discharge lamp comprises a pair of electrodes, at least one of which has an electrode main body portion and an axis portion and/or a taper portion formed between the electrode main body portion and the axis portion, wherein in the at least one of the electrodes, the axis portion has an outer diameter smaller than that of the electrode main body portion, and at least one groove extending in an axis line direction of the electrode is formed in the electrode main body portion, the axis portion or the taper portion.