Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Patent
1985-03-04
1987-09-01
DeMeo, Palmer C.
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
313623, 313634, 313632, 445 29, H01J 932, H01J 936, H01J 6136, H01J 6106
Patent
active
046906525
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wall-stabilized infrared flash tube having a lead fused inside a glass vacuum tube, and in particular to such a flash tube wherein the interior flash chamber of the tube has dimensions selected to minimize the influence of white light on the tube output.
2. Description of the Prior Art
Flash tubes are known in the art wherein, for a high light yield, the glass bulb has an inside diameter of, for example, only 1 mm and the filling pressure for the inert gas in the interior of the bulb is set to relatively high values of at least 1.3 Pa. Due to the pressure increase and the reduction of the cross-section, the component of visible light in the radiation emitted by the tube is increased and accordingly the specific frequency spectrum of the excited inert gas is marked and attenuated by a high component of white radiation.
SUMMARY OF THE INVENTION
It is an object of the present application to increase the efficiency of a wall-stabilized infrared flash tube by suitably selecting the interior dimensions of the flash chamber, and to provide a method for manufacturing such a flash tube.
The flash chamber in the flash tube disclosed herein has a length of approximately 20 mm and an interior dimension in the range of approximately 0.6 mm to approximately 1.3 mm.
Contary to expectations, no increase in the white radiation component occurs in infrared flash tubes due to such a reduction of the inside diameter of the glass bulb; to the contrary, the intensity of the spectral lines of the excited gas intensified, particularly in the infrared range. Xenon is preferably employed as the inert gas.
The infrared yield again noticeably decreases below the above lower limit for the inside diameter of the glass bulb. This effect is probably due to cooling of the gas by the glass bulb. At the same time, the glass bulb is heated to such degree by the discharge concentrated in a very tight space that, at least given the employment of the standard glass types for such glass bulbs, a considerable region of its inside surface is fused and decomposed, so that decomposition products precipitate on the cathode and render it ineffective ("poisoning"). In comparison thereto, a tube constructed in accord with the invention achieves an increase of from 30% to 50% in the yield of infrared radiation in comparison to commercially available tubes having an interior diameter of 1.9 mm when excitation pulses having the same energy are employed.
Given such tubes, the energy of the excitation pulses should lie between about 1J and 2J. The emission of visible light should be optimally low. This object is achieved in an especially advantageous fashion in an embodiment wherein the cathode lead has the largest possible outside diameter within the framework of allowable mechanical tolerances, wherein the outside diameter of an electrode member connected to the lead is not greater than that of the lead, and wherein the electrode member is secured to the lead by means of laser or electron welding. As a result of this embodiment, the dead space in the region next to and behind the electrode member is kept small. A further boost in the yield of infrared radiation and, thus, in the efficiency of the conversion of electrical energy into infrared radiation is thereby achieved.
An embodiment having an outer electrode as the trigger or control electrode is advantageous, whereby the wall thickness of the glass bulb is not greater than its inside diameter. Given this embodiment, the capacitive coupling of the standard trigger voltages of roughly 3 kV through 4 kV suffices in order to effect a sure ignition of the tube.
Such tubes are advantageously manufactured by a method wherein a cylindrical electrode member having a cylinder height of at least 1.2 mm which is coated and/or saturated with an activator is held at its generated surface and is welded to the cathode lead by means of a laser and the lead is then fused vacuum-tight into the glass bulb. The cylinder height of t
REFERENCES:
patent: 3105917 (1963-10-01), Van den Broek
patent: 3230028 (1966-01-01), Kayatt
patent: 3593056 (1971-07-01), Degawa et al.
patent: 4097762 (1978-06-01), Hilton et al.
DeMeo Palmer C.
Heimann GmbH
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