Short-Arc Discharge Lamp Electrode Scale-Like Structure
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Solution Overview
Problem
Short-arc discharge lamps face issues with heat radiation layer peeling due to thermal expansion differences between electrode materials and the heat radiation layer, leading to reduced light transmittance and short lamp life.
Innovation Solution
A scale-like structure with flaky protrusions is formed on the electrode surface, covered by a coating film containing metal oxides, carbides, borides, silicides, or nitrides, which provides enhanced thermal emission and an anchor effect to prevent peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat radiation layer containing metal oxide is formed on the electrode surface, then the heat radiation ability is improved, but the layer is likely to be peeled off due to thermal expansion difference
Solution Approach 1:
The patent applies different surface treatments to different regions of the electrode. The tip portion (emission surface) is kept smooth to maintain electron emission performance, while the non-tip portion receives the scale-like structure treatment to enhance adhesion. This local differentiation resolves the contradiction by applying the heat radiation layer only where adhesion enhancement is needed, not where emission performance would be compromised.
Solution Approach 2:
The scale-like structure is formed on the electrode surface before applying the heat radiation layer. This preliminary action creates an anchor effect that prevents peeling during subsequent thermal cycling, while the smooth tip portion maintains its emission capability. The sequence of operations ensures both adhesion strength and emission performance are achieved.
2Reliability
If the electrode surface is made uneven by blast treatment to increase anchor effect, then peeling resistance is improved, but the emission surface quality deteriorates
Solution Approach 1:
The patent selectively applies the scale-like structure only to the non-tip portion of the electrode, leaving the tip portion (emission surface) smooth. This local differentiation ensures that the anchor effect is provided where needed for adhesion, while the emission surface maintains its high quality for optimal electron emission performance.
3Temperature
If a heat radiation layer is formed on the electrode, then electrode temperature is reduced, but light transmittance decreases due to blackening
Solution Approach 1:
The patent extracts the heat radiation layer from the tip portion (emission surface) and applies it only to the non-tip portion. This separation ensures that the electrode temperature is reduced in the body where heat generation occurs, while the emission surface remains free of the coating to maintain high light transmittance and avoid blackening.
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 a short-arc discharge lamp with improved heat radiation ability and extended lifespan by maintaining the integrity of the heat radiation layer.
Implementation Method 1
forming a heat radiation layer on an electrode surface... excellent heat radiation ability
Implementation Method 2
A part of the coating film enters a space sandwiched between the back surface and the outer surface... anchor effect
Data Source
AI summary
A short-arc discharge lamp includes a pair of electrodes disposed facing each other inside a light-emitting tube, a scale-like structure being formed on an outer surface of at least one electrode of the pair of electrodes, and a coating film covering the outer surface on which the scale-like structure is formed. The scale-like structure includes a plurality of flaky protrusions protruding from the outer surface in a direction inclined with respect to a normal direction of the outer surface, each flaky protrusion having a front surface whose angle formed with the outer surface is an obtuse angle and a back surface whose angle formed with the outer surface is an acute angle. The coating film contains at least one of metal oxides, metal carbides, metal borides, metal silicides, and metal nitrides. A part of the coating film enters a space sandwiched between the back surface and the outer surface.