Electric lamp and discharge devices – Having heating means to control gas/vapor – gas or vapor...
Reexamination Certificate
1998-09-25
2001-03-13
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
Having heating means to control gas/vapor, gas or vapor...
C313S550000
Reexamination Certificate
active
06201347
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a low-pressure discharge lamp provided with a light-transmitting discharge vessel which encloses a discharge space in a gastight manner and which contains an ionizable filling comprising an evaporable component, and further provided with a holder having an opening and with a resilient body which fastens the holder in a tube which is in communication with the discharge space, which low-pressure discharge lamp is further provided with means for maintaining a discharge in the discharge space.
Such a low-pressure discharge lamp, containing mercury as the evaporable component, is known from DE 25 11 417 AS. The holder is designed here for dispensing the mercury during lamp manufacture. The tube in which the holder is accommodated serves as an exhaust tube through which the discharge vessel is evacuated and filled during lamp manufacture. The resilient body is fused at one end in an end portion of the discharge vessel and at its opposite end clamps the holder against the wall of the exhaust tube. To counteract a loss of mercury, the holder is not opened until after evacuation and filling of the discharge vessel and after closing of the exhaust tube by fusion, for example in that the holder is heated through high-frequency induction. It is a disadvantage that the holder requires many operations in the manufacture of the known lamp, such as closing of the holder, fastening of the resilient body in the tube, positioning of the holder, and opening of the holder.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a low-pressure discharge lamp of the kind mentioned in the opening paragraph which is simpler to manufacture. The lowpressure discharge lamp according to the invention is for this purpose characterized in that the resilient body has a first portion which is clamped in the opening of the metal holder, and a second, folded portion which is clamped in the tube. In the manufacture of the lamp according to the invention, the first portion of the resilient body is provided in the opening of the holder and the holder is subsequently pinched together in that location, after a material such as mercury, an amalgam, an amalgam-forming metal, or an amalgam-forming alloy has been provided in the holder. The holder is fastened to the resilient body thereby and the opening in the holder is reduced at the same time. Then the holder can be passed into the tube. The second, folded portion of the resilient body keeps the holder fastened in the tube then. It was found that on the one hand mercury vapor is capable of passing through the resulting opening in a sufficient quantity for rendering possible lamp operation. On the other hand, the resulting opening of the holder is sufficiently small for preventing a loss of material in liquid or solid form from the holder. If so desired, the tube which is in communication with the discharge space may be cooled during manufacture until it is closed so as to counteract also the evaporation of any material from the holder.
The resilient body is constructed, for example, as a metal tape. In a practical embodiment, the resilient body is a wire, for example having a thickness of a few tenths of a millimetre up to approximately one millimetre. The resilient body can then be readily fastened to the holder.
The holder of the lamp according to the invention may be subject to comparatively strong mechanical loads during manufacture. It may happen then that the wire works itself loose from the opening of the holder under the influence of vibrations. In a favorable embodiment, the first portion of the wire has a thickened end. This counteracts a detachment of the wire caused by vibrations.
In a yet more favorable embodiment, the first portion of the wire is bent into a U-shape. This measure, too, contributes to the fastening of the first end portion of the wire in the holder. In addition, the dimensions of the remaining opening of the holder may then be readily chosen through a choice of the thickness of the wire and the width of the U-shape, i.e. the distance between the centre lines of the legs of the U-shape.
If mercury is used as the evaporable component in the ionizable filling, the holder and the resilient body may be manufactured from metals which do not form amalgams and which are usual for low-pressure mercury discharge lamps, such as niobium, tantalum, iron, nickel, chromium, or alloys thereof.
In an attractive embodiment, the resilient body supports an auxiliary amalgam. A separate fastening of the auxiliary amalgam is not necessary then. The auxiliary amalgam may be directly applied to the resilient body, but alternatively it may be provided on a carrier, for example made of gauze.
It is favorable for a good operation of the auxiliary amalgam if the resilient body extends into the discharge space.
It is self-evident that the nature of the means for maintaining the discharge is immaterial to the invention. Said means may be constructed, for example, as a pair of electrodes, which may or may not be positioned in the discharge vessel. Alternatively, the means may be constructed as a coil by means of which an alternating magnetic field is generated in the discharge space during operation. Preferably, the coil is positioned outside the discharge space because electrical lead-throughs into the discharge vessel are thus avoided.
REFERENCES:
patent: 4924145 (1990-05-01), Buschmann
patent: 5841229 (1998-11-01), Borowiec et al.
patent: 5912536 (1999-06-01), Michiels et al.
patent: 2511417 (1976-11-01), None
patent: 2306765 (1997-07-01), None
patent: 2306765A (1997-07-01), None
Patent Abstract of Japan 60-10551 A, Toshiba, Jan. 1985, Claims 1-6, Manufacture of Low Pressure Mercury Vapor Discharge Lamp.
Patent Abstract of Japan: 610551; Publication Date.
Faller F. Brice
Hopper Todd Reed
Patel Nimeshkumar D.
U.S. Philips Corporation
LandOfFree
Low-pressure discharge lamp does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Low-pressure discharge lamp, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Low-pressure discharge lamp will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2525016