US2420831A - Electric lamp and bulb - Google Patents

Description

May 20, 1947. MCGOWAN 2,420,831

ELECTRIC LAMP AND BULB Filed Sept. 3, 1943 INVENTOR ME MG'OWfl/V.

WWM

ATTORNEY Patented May 20, 1 947 ELECTRIC LAMP'AND BULB Michael E. McGowan, Bloomfield, 1., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 3, 1943, Serial No. 501,075

'8 Claims. 1

This application is a continuation-in-part of my copending application, Serial No. 345.310, filed July 13, 1940, for Method of sealing-in and molding lamp bulbs, which is a division of what is now Patent No. 2,212,842, dated October 27,

This invention relates to bulbs, such as those for incandescent electric lamps and similar devices, and more particularly to such having their necks shaped to form an annular abutment to provide a seat for the edge of the lamp base.

The manufacture of devices for lamps of the above character, such as incandescent electric lamps, includes the operation of uniting what is termed a stem or mount, including a glass flare tube, to the neck portion of a bulb. In addition to the sealing-in operation, it is desirable to shape the united parts, while still plastic, so that when completing the lamp another part termed the base may more readily be applied and held in fixed relation to the bulb.

The present invention includes a bulb with its neck formed or shaped to receive a base. The formation of the bulb neck is important and has been accomplished heretofore by molding members, such as shown in Patent No. 2,006,231, dated June 25, 1935. This patent shows a bulb'neck formed to receive a base but, as will be noted, the contour of the neck in cross section involves rounded surfaces. This follows the ractice of avoiding sharp corners although it is of great advantage to provide a flat shoulder to hold the base, particularly when used with what is termed a mechanical base, when the latter is held by tabs or the like instead of cement.

The present invention provides the bulb neck with a. sharp or substantially right angular shoulder or annulus to form a flat face or contact surface which cooperates with other means to hold the base against relative movement when attached to a bulb neck. Although a sharp cornered shoulder is contrary to previous teachings and practice, bulbs shaped in accordance with the present invention have been subjected to the usual tests, including the storage of lamps over a period of months for the determination of developed cracks, and it was found that they were A further object of my invention is a lamp bulb with a neck portion specially formed for the reception of a base.

Other objects and advantages of the invention willbecome apparent as the description proceeds.

Referring to the drawings:

Fig. 1 is an elevational view of a lamp embodying my invention.

Fig. 2 is an enlarged fragmentary view of the neck portion of the lamp bulb shown in Fig. 1, before application of the base.

Fig. 3 is a bottom plan of the bulb shown in Fig. 2.

Fig. 4 is a view corresponding to Fig. 2, but showing a bulb neck and applied base partly in section. v

Fig. 5 is a fragmentary view corresponding t Fig. 4 but showing a prior lamp bulb and base connection.

Although the present application relates only to a lamp and bulb portion thereof, yet such a bulb is desirably constructed with the use of a machine as described and claimed in Patent No. 2,212,842, dated August 27, 1940, the method desirably employed being described and claimed in my copending application, Serial No. 345,310, filed July 13, 1940, so it is not necessary in the present case to describe said machine and method.

Referring to the drawings in detail, there is shown a lamp l0 comprising a bulb portion l I and a metal base portion I2. The bulb portion of the present embodiment comprises a main or generally spherical portion 13 and a neck or generally cylindrical portion II which connects with the generally spherical portionby an approximately frusto-conical ,portion l5. The frusto-conical portion [5 is united with an intermediate cylindrical band l8 by an annular portion II, forming an external shoulder l8 lying in a plane disposed at right angles to the axis of the bulb or neck thereof. The outer surfaces of the portions l6 and I! makea fairly sharp external right angle l9, as indicated most clearly in Figs. 2 and 4.

Enclosed in the neck portion of the bulb is the lamp mount 2| comprising a flare tube 22 having a press 23 through which lead-in conductors 24 and 25 extend to a filament 2B. The filament may be supported from an arbor 21 extending from the press 23, as by means of wire 20, in a conventional manner as will be understood. The flare tube 22 also includes an exhaust tube 29 communicating with the interior of the bulb by means of aperture 3| adjacent the press 23. The bottom, or external portion 32 of the flare tube, is generally annular and perpendicular to the axis it corresponds closely with-the internal diameter of the edge portion of the associated threaded base I! so that said base, when applied as shown in Fig. '4, is centered closely thereby with said edge portion, preferably corresponding in diameter with the maximum or crest diameter of the threads 36, in tight engagementv with the shoulder I 8 in the angle l3, except for the tight clamping-of the lead-in conductor 25 therebetween. The other lead-in conductor 24 extends through and is soldered to the center contact 35 of the base.

The diameter of the smaller cylindrical portion 33 desirably corresponds approximately with the internal or root diameter of the threads 36 on the base, although it may be enough smaller to allow for a desired amount of cement 31 to be disposed therebetween, as shown in Fig. 4. If desired, indentations or grooves 38 may be provided in the cylindrical portion 33 to increase the bond between the bulb neck and the securing cement.

Heretofore in the molding of a bulb neck it has been the practice to carefully avoid any sharp comers, as illustrated for example in Fig. 5, where neck portion ll of the bulb I which may have conventional indentations 38 is shown connected to the base I! by cement 31, but with no right angular shoulder and without any cylindrical portion embraced by the unthreaded edge of the base, as in Fig. 4. The reason for this prior construction is that it was believed that sharp bends or angular shoulders would subsequently cause cracks by reason of strains set up in the glass. In lamp making, however, it is of great advantage to provide a sharply defined shoulder, especially in cases where it is necessary or desirable to have a close fit between a base and a bulb neck, as illustrated in Fig. 4.

I have, therefore, ignored prior teachings in making the present invention and provided a bulb so formed that the neck is shaped with a right angular shoulder or abutment l8, and by reason of the method of sealing and shaping, as described in the copending application and parent patent referred to, the bulbs are found to be free from detrimental strains. Tests, including the manufacture and storage of bulbs so made, clearly shows that when produced in accordance with my invention they are free from cracks and resist the rough handling attending shipment as well as the lamps made heretofore, if not to a greater extent.

The bulb neck is formed so that it provides a cylindrical plug or extension 33 with a relatively sharp edge 39. Between said plug and adjacent to the abutment /|8 is formed the ring l6 which is desirably so proportioned that it snugly fits the inner surface of the unthreaded portion of the associated base l2, which is usually in the form of a metal shell. Thus when a base is positioned to surround the bulb neck it is fitted to the surface of the ring it and pressed a ainst the seat of abutment l8. The extension 33 'desirably corresponds generally with the minimum diameter of the base threads and flares outwardly on a concave surface 34 to unite with the rin or cylindrical portion l6.

The hereinbefore mentioned advantages atbeen used in connection with a baseto be secured by mechanical means, such as shown and described in 'my Patent No. 2,119,681, dated June 7, 1938. The abutment and sharp corner formation is of great importance, however, in connection with cement-secured bases, as illustrated in Fig. 4. With the construction shown in this figure, the base, whether of plain tubular or threaded form, desirably frictionally fits the bulb neck at the cylindrical po tion i6 and it has been found that when basing cement is employed, the quantity necessary is relatively small and that a fraction of the amount ordinarily used serves to hold the base in place. By making the abut- .ment and annular seat and by proportioning the lower end 33 of the extension of such diameter as to contact the inner surface of the threaded portion of the base, when a threaded base is used, such a base is held against lateral movement and the only duty of the cement is to prevent relative endwise movement.

The structural arrangement of the bulb neck and base is such that very little strain is imposed on the cement and the base is effectively prevented from rocking. A very thin layer of cement serves to hold the base against removal, resulting in economy which is an important factor in connection with articles such as incandescent electric lamps produced in great quantities.

Although a preferred embodiment of my invention has been disclosed, it will be understood that modifications may be made within the spirit and scope of the appended claims:

I claim:

1. A bulb comprising a neck portion in the form of a plug with a plain cylindrical portion for axial insertion into a base, an annular abutment extending from said neck portion, said abutment having a surface disposed in a plane substantially normal to the longitudinal axis of said bulb to seat the upper edge of said base.

2. A bulb comprising a neck portion in the form of a plug for axial insertion into a base, an annular abutment extending from said neck portion, said abutment having a surface disposed in a plane substantially normal to the longitudinal axis of said bulb to seat the upper edge of a base, and a cylindrical surface adjacent to said abutment and proportioned to firmly contact with the interior surface of said base adjacent to said edge.

3. A bulb comprising a neck portion in the form of a plug for axial insertion into a standard threaded base having the inner diameter of the threaded portion less than the upper portion adjacent to the edge thereof, an annular abutment integral with said bulb and having a surface lying in a plane normal to the longitudinal axis of said bulb ,to provide a seat for the edge of said base, said plug having a cylindrical surface proportioned to fit said upper portion of said base and a portion of less diameter to allow it to fit within said threaded portion. I

4. A bulb comprising a generally cylindrical neck portion extending below a shoulder integral with the bulb, and joined to said shoulder by a cylindrical ring portion having a diameter intermediate that of the shoulder and neck portion, and connected to the latter by a curved flaring portion, said shoulder having a surface disposed in a plane substantially normal to the iongitudinal axis of the bulb.

5. A lamp comprising a main generally spheridrical portion being united to said flaretube by an annular portion of the latter.

' 6. In combination, a bulb comprising a generally cylindrical neck portion extending below a shoulder integral therewith, said shoulder having a surface disposed in a plane substantially perpendicular to the longitudinal axis of the bulb, and a base cemeted to said neck portion and comprising a generally cylindrical edge portion fitting said generally cylindrical neck portion and abutting said shoulder.

'7. In combination, a bulb comprising a neck portion terminating in a generally cylindrical portion joined to a shoulder thereon, lying in a plane substantially normal to the bulb axis, by a flaring portion and cylindrical band of a diameter intermediate said neck and generally cylindrical portion. and a metal base member threaded to fit a socketand having an edge portion corresponding in diameter with the crests of said threads and fitting said cylindricalband, the root diameter of said threads corresponding with the generally cylindrical portion, and means disposed between said threads and generally cylindrical portion for securing said base to said bulb. 4

8. A bulb comprising a neck portion in the form of a plug, for insertion into a base formed as a hollow generally-cylindrical portion substantially closed at the bottom by an insulator portion carrying a center contact, threaded, and having a plain portion near its free edge, and a lateral extension integral with said bulb and forming a shoulder disposed in a plane substantially perpendicular to the longitudinal axis of the bulb to seat the upper edge of such a hollow base portion, said plug near the extension being proportioned to contact with the interior wall of the plain portion of said hollow base portion, to cooperate with said lateral extension and hold the base aligned with said bulb.

MICHAEL E. MCGOWAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,232,741 West July 10, 1917 1,957,708 Gustin et al May 8, 1934 2,028,884 Thomas Jan. 28, 1936 2,091,233 Zabel Aug. 24, 1937 2,077,199 Asmussen Apr. 13, 1937 620,640 Cazin Mar. 7, 1899 1,563,999 Kiriak Dec. 1, 1925 FOREIGN PATENTS Number Country Date 16,542 Switzerland July 20, 1898 112,190 Austria Sept. 15, 1928 461,455 Great Britain Feb. 17, 1937 4,174 Great Britain Feb. 25, 1896

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