US3868531A

US3868531A - Electric incandescent lamp and method of manufacturing same

Info

Publication number: US3868531A
Application number: US390166A
Authority: US
Inventors: Fraeye Dirk Jules Remi De; Jan Alfons Catharina Mewissen
Original assignee: US Philips Corp
Current assignee: US Philips Corp
Priority date: 1972-09-13
Filing date: 1973-08-20
Publication date: 1975-02-25
Anticipated expiration: 1992-02-25
Also published as: FR2199196B3; BE804738A; FR2199196A1; DE2342739A1; NL7212382A; JPS4965681A; GB1436139A; IT995312B; CA995732A

Abstract

The invention relates to an electric incandescent lamp which comprises a lamp cap having hollow contact pins, in which current conductors emerging from the lamp envelope are soldered in the cavity of the contact pins. On the free end of the contact pin the cavity is open and shows a narrowing in which the current conductor projects with a small amount of play. The part of the cavity present near the free end of the contact pin and a part of the narrowing are filled with soldering material. The invention furthermore relates to a method of manufacturing such an incandescent lamp in which during the soldering operation the contact pins assume a position in which their free end is uppermost. The invention finally relates to an incandescent lamp manufactured by said method.

Description

Unite tates Patent [191 De Fraeye et al.

[4 1 Feb. 25, 1975 1 ELECTRIC INCANDESCENT LAMP AND METHOD OF MANUFACTURING SAME [75] Inventors: Dirk Jules Remi De Fraeye; Jan

Alfons Catharina Mewissen, both of Emmasingel, Eindhoven, Netherlands [73] Assignee: U.S. Philips Corporation, New

York, NY.

[22] Filed: Aug. 20, 1973 211 Appl. N04 390,166

[30] Foreign Application Priority Data Sept. 13, 1972 Netherlands 7212382 [52] US. Cl 313/318, 313/222, 339/144, 339/275 B [51] Int. Cl 1101] 5/48, I-IOlj 5/50 [58] Field of Search 313/222, 318,113,; 339/244, 245, 246, 144, 145, 146, 275 B,

[56] References Cited UNITED STATES PATENTS 2,745,982 5/1956 Breadner et al. 313/318 X Primary ExaminerAlfred E. Smith mhmatfiaeemiaes fie Chatmom Attorney, Agent, or Firm-Frank: Trifari [57] ABSTRACT The invention relates to an electric incandescent lamp which comprises a lamp cap having hollow contact pins, in which current conductors emerging from the lamp envelope are soldered in the cavity of the contact pins. On the free end of the contact pin the cavity is open and shows a narrowing in which the current conductor projects with a small amount of play. The part of the cavity present near the free end of the contact pin and a part of the narrowing are filled with soldering material. The invention furthermore relates to a method of manufacturing such an incandescent lamp in which during the soldering operation the contact pins assume a position in which their free end is uppermost. The invention finally relates to an incandescent lamp manufactured by said method.

4 Claims, 4 Drawing Figures ELECTRIC INCANDESCENT LAMP AND METHOD OF MANUFACTURING SAME The invention relates to an electric incandescent lamp which comprises a lamp cap of an insulating material which has hollow contact pins, in which a current conductor emerging from the lamp envelope is soldered in the cavity of each pin. Such an electric incandescent lamp is known.

In manufacturing said known incandescent lamps which are usually constructed as projection lamps, the soldering operation consists in that a member of a solid soldering material which is inserted into the cavity of the pin together with the current conductor is melted by heating after which the current conductor is secured in the contact pin upon cooling and solidification. The member of solid soldering material is inserted into the cavity of the pin via an aperture in the pin, said aperture being present at the area where the pin is secured to the insulating material of the lamp cap. As long as the soldering material has not yet solidified, the lamp envelope can be aligned relative to the lamp cap for example, by optical means. After termination of the soldering operation, the lamp cap is filled with cement to reinforce the connection of the lamp envelope to the lamp cap.

The drawback of this known method of manufacturing is that upon heating the soldering material in the pins, which heating may be a high-frequency heating and also a heating by means of gas flames, the material of the lamp cap is also heated in the proximity of the connection of the contact pins. This results in a nonuniform expansion of the material of the light cap, which, in particular with the frequently used ceramic material, may give rise to cracking of the lamp cap.

It is the object of the invention to provide an incandescent lamp the contact pins of which are constructed so that during the manufacture of said incandescent lamp the possibility of damage to the lamp cap is very small.

For that purpose, the electric incandescent lamp of the above-mentioned type according to the invention is characterized in that a space which opens into the free end of the contact pin remote from the lamp cap forms part of the cavity, said space being at least partly filled with soldering material and, viewed in the direction of the lamp cap, having a narrowing through which the current conductor projects with a small amount of play. This design of the contact pins makes it possible that during the soldering operation a member of a solid soldering material is introduced into the aperture of the said space. This member may even project beyond the contact pin: in this case the contact pin should be kept with its free end uppermost during melting of the soldering member so that the liquid solder flows into the aperture of the contact pin. Because in this case only the part of the contact pin which is farthest remote from the lamp cap is heated, the possibility of damage to the lamp cap is very small.

When the soldering operation is carried out with the free end of the contact pin uppermost, the possibility exists that the liquid solder lands in the lamp cap via the play between the inner wall of the narrowing and the current conductor, which is undesirable because the warm solder gives rise to a local rise in temperature. In order to prevent this, the amount of the play, the viscosity of the solder, the temperature of the contact pin and the length of the narrowing should be chosen to be so that the limit of the solidified mass of solder present on the side of the lamp cap lies within the narrowing.

The narrowing, viewed from the free end of the 5 contact pin, preferably has a portion which widens in the form of a funnel. This actually facilitates the insertion of the current conductor into the contact pin.

The invention furthermore relates to a method of manufacturing one of the above-described electric incandescent lamps in which a member of a solid soldering material inserted into the cavity of a contact pin together with a current conductor is melted by heating and upon solidification secures the current conductor in the contact pin, which method is characterized according to the invention in that the soldering material is inserted into the cavity of the pin via the aperture in the free end of the contact pin remote from the lamp cap, the contact pin during the soldering operation assuming a position in which said aperture is uppermost. As already stated above, the advantage of this method is that damage to the lamp cap does not occur. Actually, in this position of the lamp cap the material thereof is not heated by rising warm air, while it is possible to arrange the heating members in such manner that mainly the free end of the contact pin farthest remote from the lamp cap is heated.

A favourable embodiment of the method according to the invention is characterized in that the member of solid soldering material after its provision into the aperture of the contact pin and prior to melting said member projects partly outside the contact pin. Upon heating, liquid soldering material flows into the aperture of the contact pin. An advantage of this embodiment is that the heating of the soldering material occurs directly; in the known method on the contrary the heating of the solid member of soldering material is carried out by the heating of the contact pin.

A further favourable embodiment of the method according to the invention is characterized in that the member of solid soldering material is high-frequency heated while using a coil which surrounds the part of the member projecting beyond the contact pin and the free end of the contact pin. With this arrangement of the high-frequency coil, heating of the material of the lamp cap is substantially entirely prevented so that the possibility of damage to the lamp cap remains very small.

According to still another favourable embodiment of the method according to the invention the member of solid soldering material has the shape of a helically wound wire. This member of solid soldering material, however, may also be shaped as a hollow cylinder which is manufactured, for example, of bent sheet material.

The invention furthermore relates to an electric incandescent lamp manufactured by any of the abovedescribed methods.

The invention will be described in greater detail with reference to the drawing, in which:

FIG. 1 is a longitudinal sectional view of a contact pin during the manufacture of an electric incandescent lamp according to the invention, with the member of solid soldering material used,

FIG. 2 shows the contact pin shown in FIG. 1 after the soldering operation,

FIG. 3 shows diagrammatically a device for connecting the lamp cap to the lamp envelope by the method according to the invention, and

FIG. 4 shows another embodiment of the member of solid soldering material.

The contact pin shown in FIG. 1 comprises a cavity which is mainly constructed from three parts: the upper space 2 which opens into the atmosphere, the narrowing 3 which changes into a widening 4. A current conductor 5 is inserted into the contact pin 1, while a helically wound member 6 of soldering material is arranged above the contact pin and partly in the space 2. The transition from the widening 4 to the narrowing 3 is in the form of a funnel so that when inserting the current conductor into the contact pin it easily finds its way in the cavity of the pin. Only a very small amount of play exists between the current conductor and the narrowing 3. FIG. 1 furthermore shows diagrammatically a high-frequency coil 7. By heating the member 6 by means of the coil 7, the solder melts and flows into the space 2 in the liquid condition. Because as a result of the arrangement of the high-frequency coil only the free end 8 of the contact pin is mainly heated and the remaining part of the contact pin remains cold, the liquid solder which flows into the space between the current conductor and the narrowing will cool before the flow of liquid has reached the widening 4. As shown in FIG. 2, the lower limit of the solidified solder is in the proximity of the edge 9 which marks the transition of the narrowing to the widening. The space 2 is filled substantially entirely by the solidified solder 9.

Instead of a body which is formed from a helically wound wire, a cylindrical member of solder may also be used. Such a member is shown in FIG. 4.

As shown in FIG. 3, the lamp cap 10 during the manufacture of the lamp is secured in a stand 11. The

contact pins

12 and 13 project through the bottom portion 14 of the stand 11. The lamp envelope 15 of the incandescent lamp to be manufactured with the filament 16 arranged therein is supported by a holder (not shown) which is movable relative to the stand. The movements of the holder are controlled by an adjusting device comprising optical auxiliary means. The free ends of the

contact pins

12 and 13 are each surrounded by high-frequency coils l7 and 18, respectively. The

bottom portion 14 is further covered by a hood 19 below which a reducing gas is present during the soldering operation.

When the filament has been aligned relative to the lamp cap and the soldering operation has been carried out, the incandescent lamp is removed from the stand after which the space between the lamp cap 10 and the lamp envelope 15 is filled with a cement to reinforce the mutual connection.

It will be obvious that instead of a high-frequency coil, flames may also serve as heating members.

If desired, the free ends of the contact pins may be ground after the soldering and cementing operation.

What is claimed is:

1. An electric incandescent lamp having an envelope which comprises a lamp cap manufactured from an insulating material a pair of elongated contact pins each having an axial passageway therein, said pins being carried by said lamp cap, and a current conductor extending from the lamp envelope through each passageway, each of said conductors being soldered in said passageway in which said conductor is disposed, each of said passageways comprising first, second and third axial sections, said second axial section having a crosssectional area smaller than said first and third sections, said third section being disposed distal to the lamp envelope and being the axial extremity of said pin, said third axial section being at least partly filled with solder each of said axial sections being dimensional in closely spaced engagement with the circumference of said conductor carried therein, said closely spaced relationship permitting the flow of molten solder therebetween and substantially limiting radial play therebetween.

2. An electric incandescent lamp as claimed in claim 1 wherein said solder extends axially in each of said contact pins into said second axial section.

3. An electric incandescent lamp as claimed in claim 2, wherein said third axial section forms a truncated cone in the axial portion thereof proximate said second axial section.

4. The apparatus as described in claim 1 wherein said first and third axial sections taper smoothly into said second axial section.

Claims

1. An electric incandescent lamp having an envelope which comprises a lamp cap manufactured from an insulating material a pair of elongated contact pins each having an axial passageway therein, said pins being carried by said lamp cap, and a current conductor extending from the lamp envelope through each passageway, each of said conductors being soldered in said passageway in which said conductor is disposed, each of said passageways comprising first, second and third axial sections, said second axial section having a cross-sectional area smaller than said first and third sections, said third section being disposed distal to the lamp envelope and being the axial extremity of said pin, said third axial section being at least partly filled with solder each of said axial sections being dimensional in closely spaced engagement with the circumFerence of said conductor carried therein, said closely spaced relationship permitting the flow of molten solder therebetween and substantially limiting radial play therebetween.