US 3857056 A
A wedge base light bulb comprises an inner glass filament support and exhaust tube and an outer glass envelope and base. The bulb filaments are mounted by fusion retention of the filament support legs in slots formed in a flared end of the tube. The outer envelope encircles the filaments. The base is fusion sealed about the filament support legs and the exhaust tube. The base has a plurality of longitudinal ribs adapted to be frictionally received in a wedge base bulb socket. The ends of the support legs are formed along the ribs for making electrical contact with the socket terminals.
Description (OCR text may contain errors)
United States Patent Miller et al.
[ 3,857,056 [451 Dec. 24, 1974 WEDGE BASE LIGHT BULB Inventors: John S. Miller, Anderson; Lloyd T.
Fuqua, Portville, both of 1nd.
Assignee: General Motors Corporation,
Filed: Oct. 26, 1973 Appl. No.: 410,016
U.S. Cl 313/318, 313/272, 313/275, 313/315, 29/2513 Int. Cl H0lj 5/48, HOlj 5/50 Field of Search 313/318, 275, 276, 272, 313/273, 315; 29/25.13
References Cited UNITED STATES PATENTS 5/1933 Severin 313/272 10/1944 Flaws, Jr 313/275 X S/1960 Howles et al. 313/315 2,999,180 9/1961 Howles et al. 313/318 3,265,922 8/1966 Verbeek 313/318 3,345,526 10/1967 Wright 313/275 X Primary Examiner-James W. Lawrence Assistant Examinen-Saxfield Chatmon, Jr.
Attorney, Agent, or Firm-Peter D. Sachtjen  ABSTRACT A wedge base light bulb comprises an inner glass filament support and exhaust tube and an outer glass envelope and base. The bulb filaments are mounted by fusion retention of the filament support legs in slots formed in a flared end of the tube. The outer envelope 2 Claims, 5 Drawing Figures Patented Dec. 24, 1974 3,857,056
unnnnnnnenv WEDGE BASE LIGHT BULB The present invention relates to lighting devices and, in particular, an all glass wedge base light bulb formed from two pieces of glass tubing.
It is becoming increasingly desirable to provide automatic assembly of bulbs and sockets into motor vehicle wiring harnesses. The present invention provides an all glass wedge base bulb which is axially inserted into indexed, locked relationship with a wedge base bulb socket in a manner that facilitates automation. More particularly, the bulb is formed of two pieces of glass tubing. An outer piece of tubing constitutes the lamp envelope and a self indexing and locking base. An inner piece of tubing functions dually as the filament support post and the exhaust tube. The inner tube is flared at one end and the outer periphery thereof is indented to receive the filament support legs. The legs are anchored to the tube by melting the adjacent glass around them. The exhaust tube then becomes the support assembly for the legs to which the filaments are then attached. The outer tube is first closed at one end to a spherical shape. The inner exhaust tube assembly is psitioned within the outer tube and the opposite end is heated and pressed into the configuration for the base. The base includes a plurality of longitudinal ribs interconnected by arcuate locking tabs. During the press sealing operation, the support legs are entrapped in the pressed glass and the free ends are reversely bent along the outer surfaces of the ribs to provide the electrical contacts. The ribs and tabs cooperate with the bulb socket to accurately and yieldably axially and circumferentially position the bulb. The interior bulb cavity is exhausted through the exhaust tube which is then pinched off to complete the assembly.
These and other features of the present invention will be apparent to one skilled in the art upon reading the following detailed description, reference being made to the accompanying drawings illustrating a preferred embodiment in which: 7
FIG. 1 is a partially sectioned side elevational view of a wedge base light bulb made in accordance with the present invention;
' FIG. 2 is a cross sectional view taken along line 2-2 of FIG. 1 showing the exhaust tube with the filament support legs captured in the indented periphery of the exhaust tube flange;
FIG. 3 is a view taken along line 33 of FIG. 1 showing the lead wires captured in the base;
FIG. 4 is a cross sectional view taken along line 4-4 of FIG. 1; and
FIG. 5 is a perspective view showing the two tubing assemblies for the bulb of FIGS. 1 through 4.
Referring to FIG. 1 there is shown an all glass wedge base light bulb made in accordance with the present invention comprising a filament support and exhaust tube 12 and an outer enclosure 14 comprising an upper envelope 16 and a lower base 18. The base 18 includes three circumferentially spaced external terminals 20.
The bulb 10 as hereinafter described in greater detail is fabricated from two pieces of cylindrical glass tubing. Referring to FIG. 5, the exhaust tube 12 is initially a hollow piece of cylindrical glass tubing 22 having an outwardly flared upper end or flange 24 and a downwardly depending lower stem 26. The upper flange 24 is initially indented with three evenly circumferentially spaced slots 27 which slidably receive three filament support legs 28. A minor support leg 30 is welded to one. of the major support legs 28. The upper ends of the legs are flattened and reversely bent to clinch thereon the ends of a pair of filaments 32. The lower ends of the support legs 28 depend downwardly along'the exterior of the tubing and extend a sufficient distance therebeyond to form the terminals 20 as hereinafter described. The subassembly thus formed constitutes a group of components including the major and minor legs 28 and 30 with filaments 32 clinched thereto and embedded in the flange of the tubing 22.
The other piece of glass tubing 40 includes a cylindrical sleeve 42 and a closed spherical upper end 44. the exhaust tube subassembly is then positioned within the sleeve 42 in the desired spacial relationship with respect thereto. By means of suitably shaped jaws, the lower end 26 is heated to an elevated temperature and the jaws closed to impress the desired base configuration upon the lower end. In final assembly, as shown in FIG. 3, the base 18 comprises three evenly spaced longitudinal ribs 50. The ribs 50 are interconnected at the lower ends thereof by arcuate wedge shaped locking tabs 52. The outer longitudinal surface of each rib 50 is provided with a groove 54. One of the ribs 50 is wider than the others to provide circumferential indexing of the filaments in assembly. The pressed base melts around the legs 28 to fixedly capture them and to effect a fusion seal with the lower exterior surface of the tubing 22. In final assembly, free ends of the legs 28 are reversly bent upwardly along the groove 54 to form the terminals 20. The interior volume of the bulb is then evacuated by suitable means through the interior passageway 60 of the exhaust tube 26. The lower end of the stem 22 is then pinched sealed at 62 to maintain the evacuated condition of the interior bulb cavity.
A completed bulb 10 as shown in FIG. 4 is adapted to be received in a suitably shaped wedge base bulb socket connected to a wiring harness, not shown. The socket 70 includes slots for the ribs and associated terminals 72 adapted to engage the terminals 20 to thereby connect the filaments 30 to a suitable electrical supply for illumination in the desired lighting mode. The socket 70 also includes spring fingers 74 which are engaged with the tabs 52 to yieldably lock and axially position the bulb 10 in the socket 70. Accordingly, with this design which is assembled by axial insertion, automation of the socket and bulb assembly is facilitated. Although only one form of this invention has been shown and described, other forms will be readily apparent to those skilled in the art. Therefore, it is not intended to limit the scope of this invention by the em- 7 bodiment selected for the purpose of this disclosure but only by the claims which follow.
What is claimed is:
l. A wedge base light bulb formed from onlytwo pieces of cylindrical glass tubing, comprising: an exhaust tube formed of one piece of glass tubing having a flange at one end including a plurality of axial slots therein; filament support legs axially positioned along the exhaust tube and projecting therebeyond, said support legs being retained at said slots by melting the ad jacent material therearound; filament means connected between the upper ends of said support legs; an outer glass enclosure formed of said other piece of glass tubing including a closed upper end encircling said filament means, said support legs'and said flange of said exhaust tube, and a lower base fusion sealed about the lower portions of the support legs and the exhaust tube;
a plurality of ribs formed on the outer surface of the base adapted to be frictionally received in a wedge base bulb socket, the lower ends of the support legs being formed along the base of the ribs for making electrical contact with the socket terminals; and a pinch seal at the lower end of said exhaust tube for maintaining an evacuated environment in the interior of the bulb as evacuated through said central passage.
2. A wedge base light bulb formed from only two pieces of cylindrical glass tubing, comprising: an exhaust tube formed of one piece of said glass tubing, said exhaust tube having a central passage therein terminat- .ing at one end in a radially flared flange having a plurality of axial slots therein; filament support legs retained outer glass enclosure formed of said other piece of glass tubing including a closed upper end encircling said filament means, said support legs and said flange of said exhaust tube, and a lower base fusion sealed about the lower portions of the support legs and the exhaust tube; a plurality of axial ribs formed on the outer surface of the base adapted to be frictionally received in a wedge base bulb socket, one of said ribs being larger than the others provide circumferential indexing of the bulb; ar cuate locking tabs formed between said ribs of said base, said locking tabs adapted to be frictionally engaged by the socket for axially positioning the bulb, the
free ends of the support legs being formed along the base of the ribs and upwardly along the outer radial sur faces of the ribs toward said closed upper end, said free ends making electrical contact with the socket terminals; and a pinch sea] at the lower end of said exhaust tube for maintaining an evacuated environment in the interior of the bulb as evacuated through said central passage.