Electric lamp and discharge devices – With temperature modifier – Double wall – jacket or casing for envelope
Reexamination Certificate
1999-06-02
2001-12-11
Day, Michael H. (Department: 2879)
Electric lamp and discharge devices
With temperature modifier
Double wall, jacket or casing for envelope
C313S026000, C313S036000, C313S634000
Reexamination Certificate
active
06329742
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a lamp of the type having a protective sleeve of quartz surrounding a light source, in particular a metal halide arc tube having a pair of opposed leads. The sleeve is supported by a metal frame comprising a pair of metal frame members which also supply current to the leads.
Protective sleeves of quartz or other transparent material able to withstand operating temperatures are commonly utilized around metal halide arc tubes, also known as high intensity discharge or HID arc tubes, in order to provide protection against non-passive failure during lamp operation. These sleeves act to slow or stop fast moving arc tube fragments and prevent the rupture of the outer lamp envelope. These sleeves may also provide other functions including, but not limited to, reduction of the UV output of the lamp.
Protective sleeves are typically mounted around the arc tube using additional straps or clips around the outside or in the ends of the sleeve. In the case of quartz metal halide arc tube, any metal supports used in the mounting must be kept away from the arc tube or be electrically floating to reduce the rate of sodium loss. An arrangement of this type, having a metal frame member outside of the sleeve, is disclosed in EP 0 784 334.
A known floodlamp having a parabolic aluminized reflector (PAR) utilizes a metal halide arc tube and a protective sleeve supported by straps attached to current carrying wire frame members outside the sleeve. The frame members are brazed into metal ferrules at the base of the reflector, and therefore must have good alignment.
U.S. Pat. No. 5,719,463 discloses a metal halide discharge lamp having a quartz metal halide arc tube with a quartz protective sleeve. A first lead wire for the arc tube passes through the inside of the sleeve and is provided with insulation to prevent sodium loss from the arc tube. This lead wire engages a dimple in the top of the ellipsoidal outer envelope to provide stability. The protective sleeve is supported by insulated stop members fitted in opposed ends of the sleeve and around the first lead wire. One of the stop members is held in place by a bend in the first lead wire, while the other is held in place by a bend in the second lead wire.
U.S. application Ser. No. 09/135,863 discloses a metal halide discharge lamp having a ceramic metal halide arc tube with a quartz protective sleeve. A first lead wire passes through the sleeve and engages a dimple in the outer envelope, but no insulation is necessary because there is no problem of sodium loss with a ceramic arc tube (such as alumina). The sleeve is held in place between a tab on the first lead wire and a terminal on the second lead wire; both lead wires are embedded in the glass stem. According to another embodiment, the sleeve is held in place by bends in the lead wires, which are welded to leads embedded in the stem.
Protected mount designs are typically quite expensive and difficult to mechanize. In addition, most mounts are insufficiently rigid and may come apart with rough lamp handling (as during transportation).
SUMMARY OF THE INVENTION
It is an object of the invention to provide a support frame for a protective sleeve around a light source, in particular a ceramic metal halide arc tube, in a lamp having an outer envelope which does not offer any means of support such as a dimple.
It is a further object, to provide a support frame which can be pre-assembled to the light source and the sleeve, so that the assembly can be fixed in the lamp as a unit.
According to the invention, a pair of frame members extend through the sleeve, and each frame member is a wire which is formed to engage the lower end of the sleeve, preferably by means of an S-shaped bend.
According to a preferred embodiment, the sleeve is held in place axially by a tab such as a getter adjacent to the upper end of the sleeve, and the upper ends of the frame members are held apart by an insulating spacer.
Each frame member is provided with a terminal to which the opposed leads of the arc tube are brazed prior to fitting the sleeve. The tab and spacer are then fixed to form a rigid self-supporting assembly wherein the lower ends of the frame members have a predetermined spacing. This permits insertion into the ferrules of a PAR-type lamp, where they are brazed in place. The lens is then fitted to the reflector without any further assembly steps being necessary.
The lamp according to the invention is therefore especially suited to applications where a pre-assembled light source and sleeve is desirable from a manufacturing standpoint, and good stability is necessary without any support by the outer envelope.
While the invention is particularly suited to lamps having ceramic metal halide arc tubes, it may also find applicability with incandescent light sources such as the IR coated tungsten-halogen lamp disclosed in U.S. Pat. No. 5,670,840.
REFERENCES:
patent: 4866342 (1989-09-01), Ramaiah et al.
patent: 5128106 (1992-07-01), Buschmann et al.
patent: 5327042 (1994-07-01), Bazin et al.
patent: 5576592 (1996-11-01), Koenigsberg et al.
patent: 5719463 (1998-02-01), Hassink et al.
patent: 784334 (1997-07-01), None
patent: 737913 (1955-10-01), None
patent: WO0011704 (2000-03-01), None
Bailey John S.
Nelson Gregory J.
Van Lierop Franciscus H.
Day Michael H.
Halajian Dicran
Philips Electronics North America Corp.
Quarterman Kevin
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