Electric lamp and discharge devices – With envelope – Having base and connector
Reexamination Certificate
2002-10-23
2004-09-14
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With envelope
Having base and connector
C313S318040, C429S472000
Reexamination Certificate
active
06791250
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to attaching a wire to the shell of a base on an electric lamp and, more particularly, to an assembly that enables the wire to be welded to the base in a way that prevents undesirable movement of the base relative to the lamp.
BACKGROUND OF THE INVENTION
The present invention relates generally to assembly of an electric lamp (i.e., a light bulb which is known in the art as a “lamp”—the “bulb” is only the outer glass envelope). In particular, the invention concerns both a means for attaching a wire to the shell of a base on the lamp, and also to a means of securing the base on the lamp. Typically, the base is attached to the neck of a “sealed lamp” wherein one of the electrical “lead wires” (a sidewire) is trapped between the bulb neck and the base, and then the sidewire is electrically connected to the side of the base. Historically, the electrical attachment is by means of soldering, but there is now a big push to avoid the use of lead (a primary component in most solders) for environmental reasons. Lamp makers have implemented various means for welding the sidewire instead of soldering, but there are many problems associated with sidewire welding. For example, heat generated in the welding process can cause damage to the glass bulb that may lead to premature lamp failure. Also, the average weld quality and amount of variation in the weld quality depend on the materials used in the welded parts, the dimensions of the welded parts, the positioning of the welded parts, and many other factors known in the welding arts.
A further set of problems is raised when sidewire welding is substituted for soldering in lamps that involve high temperature use, for example in lamps generally known as High Intensity Discharge (HID) lamps. Because of high lamp operating temperatures, basing cement is typically not used to secure the base onto the bulb; rather screw threads can be formed in the glass neck of the bulb (forming a “threaded seal”) upon which the base can be screwed onto the lamp. This is a well known process in the lamp making industry. Typically, a vertical groove is formed across the screw threads in the glass neck to provide a recess for the sidewire to lie in. Once the base is screwed on, the groove can be filled with molten solder to electrically attach the wire (in the groove) to the base shell where it passes over the groove. Once it hardens, the solder serves a desired additional purpose of locking the base in position so that it cannot be unscrewed off of the lamp. If the solder fills the groove properly, the base will not be able to move more than a degree or so relative to the bulb, and many lamp applications specify very tight limits on such movement. As a result, regulatory agencies such as ANSI (American National Standards Institute) and IEC (International Electrotechnical Commission) have published standards that require no more than a small number of degrees movement of the base relative to the bulb. When solder is replaced by welding for such lamps, new ways of securing the base to the bulb must be developed.
U.S. Pat. No. 6,346,767 (Swadel, et al.; 2002)—“Swadel”—discloses a lamp with a formed, cemented clip to secure base to lamp. The lamp's bottom portion (21) has threads (23) and a groove (25) ending in a deeper cavity (receiving port 25
a
). The side lead-in wire (34) is attached, as by welding, to a locking clip (10), and the wire-clip assembly lies in the groove such that a scyphate middle portion (16) of the clip is accepted by the receiving port. The base (32) is threaded onto the bottom threads (23) and an end portion (18) of the locking clip is welded to the base by bending the end portion over the top of the base in order to contact the outside surface of the base. An adhesive chemical attachment means (50) is located in the receiving port (25
a
) to chemically affix the locking clip (10) to the lamp end (21).
U.S. Pat. No. 5,032,759 (Thiry, et al.; 1991)—“Thiry”—discloses a lamp base (10) comprising a metal shell contact (14) containing a molded glass body (12) that has a cylindrical wall (18). The invention comprises thinning the wall (18) in an area behind the point (a weld zone 48) where a side lead (50) is to be welded to the exterior surface of the shell contact (14). The thinning is intended to deter slumping of the glass adjacent the weld zone. Thiry teaches (column 1, lines 34-49) that the existence of a gap between the glass and the shell causes welding problems due to allowed flexing of the shell when the lead is pressed against the shell by the welding tool. The welding problems are said to result in occurrences of weld failure in two to five percent of lamp production involving the subject type of base.
The Swadel patent avoids the use of solder, but does not address situations where high operating temperatures may negate the effectiveness of the adhesive used to secure the base to the lamp. The Thiry patent discloses problems that arise when resistance welding a wire to a base shell when there is a cavity with insufficient support for the shell. It is an objective of the present invention to solve these and other problems that arise when both electrically connecting a sidewire to a base and also securing the base to a lamp without using either solder or adhesive.
BRIEF SUMMARY OF THE INVENTION
According to the invention, a lamp assembly comprises a metal screw base having base screw threads; an outer jacket having a threaded seal wherein seal screw threads are formed in a neck portion of the outer jacket, such that the seal screw threads conform to the base screw threads to allow the base to be screwed onto the threaded seal; one or more lead wires extending out of a bottom of the threaded seal; a flag assembly comprising a wire in a close-fitted electrically nonconductive sleeve, the flag assembly having an outer end comprising a flag; a groove formed across the seal screw threads and dimensioned to closely fit around the flag assembly; and the flag assembly being positioned in the groove such that an inner end of the flag assembly is electrically connected to at least one of the one or more lead wires, and the flag of the flag assembly is bent over a lip of the screw base and welded to an outside surface of the screw base.
Further according to the invention, the lamp assembly is such that the wire of the flag assembly is at least one of the one or more lead wires.
Further according to the invention, the lamp assembly is such that the inner end of the flag assembly is electrically connected to at least one of the one or more lead wires by welding.
Further according to the invention, the lamp assembly is such that the flag comprises flat metal. Preferably, the flag is a separate piece of flat metal stock that is electrically and mechanically connected to the wire; and a shank portion of the flag assembly where the flat metal stock overlaps the wire is conformed to the shape of the wire and is covered by the sleeve. More preferably, the flag has a thickened portion that is positioned in the vicinity of a fold where the flag assembly is bent over the lip of the screw base; and the thickened portion traversingly extends to at least one of two lateral edges of the flag. Most preferably, the thickened portion comprises an extended end of the wire that is formed such that the extended end traverses a flat side of the flag. Further, the thickened portion extends under the sleeve enough to increase the magnitude of a sleeve covered flag thickness; and the thickened portion extends out to the fold such that the fold is able to bend around the outer end of the thickened portion.
Further according to the invention, the lamp assembly is such that the flag assembly is welded to the outside surface of the screw base by means of resistance welding.
Further according to the invention, the lamp assembly is such that the sleeve comprises a resilient, high temperature material.
According to the invention, a method for securing a base on a lamp comprises the steps of:
a) forming seal screw t
Jurkovic Paul J.
Myers, Jr. Harold D.
Westenfelder, II David A.
Cohn Howard M.
Eye Lighting International
Guharay Karabi
Patel Nimeshkumar D.
Stauffer Derry
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