UV Flame Detector Structure for Low-Noise Outdoor Sensing
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Solution Overview
Problem
Current ultraviolet (UV) sensitive flame detectors face limitations in sensitivity due to background radiation from daylight and cosmic radiation, which affects their ability to detect flames effectively both indoors and outdoors.
Innovation Solution
The design of an ultraviolet flame detector with a cylindrical housing, a photocathode, and an anode wire, filled with a gas mixture of argon, isobutane, and hydrogen, and coated with metals having a work function of at least 5 eV, along with a window structure made of transparent materials like fused silica, to enhance sensitivity and reduce background noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the flame detector uses UV sensitive photocathode to detect flames, then the detection capability for UV radiation is improved, but the sensitivity is limited by background radiation from daylight and cosmic radiation
Solution Approach 1:
The patent applies local quality by coating specific surfaces (inner housing surfaces and wire mesh) with metal having high work function (at least 5 eV) to selectively block daylight radiation while maintaining UV transmission capability. This localized treatment addresses the background radiation problem without compromising the overall detection function.
Solution Approach 2:
The patent introduces a wire mesh structure coated with high work function metal as an intermediary element between the window structure and photocathode. This intermediary blocks harmful electromagnetic interferences and background radiation while allowing UV radiation from flames to reach the photocathode for detection.
2Measurement precision
If the detector is filled with gas mixture to enhance sensitivity, then the detection sensitivity is improved, but the device complexity increases
Solution Approach 1:
The patent changes the physical-chemical parameters of the detection medium by using a specific gas mixture (argon, isobutane, and hydrogen in particular ratios) to optimize the detector's sensitivity. This parameter optimization enhances detection capability while managing the complexity through defined composition specifications.
3Illumination intensity
If the window structure is made of transparent materials to allow UV radiation, then the UV transmission is improved, but the detector is affected by electromagnetic interferences
Solution Approach 1:
The patent introduces a wire mesh structure coated with high work function metal as an intermediary element between the window structure and photocathode. This intermediary blocks harmful electromagnetic interferences while allowing UV radiation from flames to reach the photocathode for detection.
Solution Approach 2:
The patent uses composite material approach by combining transparent window material (for UV transmission) with metal-coated wire mesh (for electromagnetic shielding). This composite structure achieves both UV transparency and electromagnetic interference protection simultaneously.
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 significantly improves the detector's sensitivity to UV radiation while minimizing interference from longer wavelengths, allowing for effective flame detection both indoors and outdoors with reduced background noise and prolonged detector lifespan.
Implementation Method 1
a photocathode (106) arranged at a bottom end (101b) of the housing (102) so that the photocathode (106) is facing inside the housing (102)
Implementation Method 2
The UV flame detector 100 is filled with a gas
Implementation Method 3
which may be a mixture of the following gases: argon (Ar), isobutane (iC 4 H 10 ), and hydrogen gas (H 2 )
Implementation Method 4
the inner surfaces of the housing may be coated with a metal having a work function of at least 5 eV
Implementation Method 5
The material of the window structure may be one of fused silica, sapphire, calcium fluoride, or magnesium fluoride
Data Source
Figure 1A~1C
Figure 2A~4
AI summary
The invention relates to an ultraviolet flame detector (100). The ultraviolet flame detector comprises: a housing (102) having an opening (103) at a first end (101a) of the housing (102), a window structure (104) arranged to cover the opening (103) of the housing (102), a photocathode (106) arranged to a second end (101b) of the housing (102) so that the photocathode (106) is facing inside the housing (102), and an anode wire (108) arranged between the window structure (104) and the photocathode (106). The anode wire (108) is configured to travel transversally across the housing (102). The ultraviolet flame detector (102) is filled with a gas.