UV Enhancer Ignition Aid for High-Pressure Discharge Lamps
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Solution Overview
Problem
High-pressure discharge lamps, particularly metal halide lamps, face challenges in reliable ignition due to the need for UV radiation below 280 nm, which is not effectively transmitted through ceramic or quartz discharge vessels, and existing mercury-based UV enhancers are costly and environmentally undesirable.
Innovation Solution
The use of mercury-free UV enhancers with radiation-emitting materials and a molybdenum foil or wire electrode within a UV-transparent quartz or ceramic discharge vessel, where the foil is bent or deformed to minimize distance to the vessel wall, enhancing electric field strengths and reducing ignition voltage, and the use of doped molybdenum foils and specific gas fillings to generate UV radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a ceramic or quartz discharge vessel is used, then the lamp structure is stable and durable, but UV radiation below 280 nm is not effectively transmitted
Solution Approach 1:
The discharge vessel is segmented into an inner vessel (ceramic or quartz for structural stability) and an outer UV-transparent envelope (quartz or glass for UV transmission). This segmentation allows each component to fulfill its specific function: the inner vessel provides structural support and contains the arc, while the outer envelope transmits UV radiation effectively.
Solution Approach 2:
A UV-transparent intermediate layer or outer envelope is introduced between the ceramic/quartz discharge vessel and the external environment. This intermediary component allows UV radiation below 280 nm to pass through while the inner ceramic/quartz vessel maintains its structural integrity and contains the discharge.
2Reliability
If a foil electrode is placed close to the discharge vessel wall, then ignition voltage is reduced, but the distance control becomes difficult
Solution Approach 1:
The foil electrode is designed with elastic properties, allowing it to dynamically adapt its position. The foil can be elastically deformed during assembly to achieve the optimal small distance to the discharge vessel wall, ensuring reliable ignition. The elasticity also provides tolerance for manufacturing variations.
Solution Approach 2:
A flexible foil electrode is used instead of a rigid electrode. The thin film structure allows it to be easily positioned close to the discharge vessel wall and maintains contact through its flexibility. The foil can be bent and shaped to fit the required geometry while maintaining electrical conductivity.
3Reliability
If another metallic component is introduced into the UV enhancer to promote charge transport, then ignition is improved, but cost increases
Solution Approach 1:
The electrical parameters of the foil electrode itself are optimized to improve charge transport. By adjusting the foil's thickness, material composition, and surface properties, the electrical conductivity and charge transport capability are enhanced without introducing additional metallic components. This maintains simplicity while achieving improved ignition performance.
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 configuration ensures reliable ignition with reduced mercury content, lower ignition voltage, and increased UV intensity, making the lamps more efficient and environmentally friendly.
Implementation Method 1
UV radiation is used to reliably ignite Krypton85-free high-pressure discharge lamps. This is often provided by UV enhancers.
Implementation Method 2
UV radiation in the wavelength range
Implementation Method 3
The ignition voltage of the UV enhancer is directly dependent on the distance between the inner electrode and the inner wall of the discharge vessel. The part of the molybdenum foil that is arranged inside the discharge vessel can be partially or fully bent. This keeps the distance to the inner wall small.
Implementation Method 4
The vessel of the UV enhancer can be made of quartz or other UV-transmitting glass, especially tempered glass. In the case of a quartz glass discharge vessel, a molybdenum foil is provided, which ensures gas-tight passage through the quartz glass
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 2c~2f
AI summary
The invention relates to a high-pressure discharge lamp having an ignition aid and comprising a discharge vessel, which is accommodated in an outer bulb. The ignition aid is a UV enhancer having a can-like container (12), which has an inner electrode (18). At least part of the end-face edge of the inner electrode at least comes close to the end face (24) of the container (12). An external electrode is attached to the outside of the container.