Note: Descriptions are shown in the official language in which they were submitted.
LD 6045
~06008Z
The invention relates to metal base terminals for
electric lamps and devices having sealed envelopes of vitre-
ous material provided with an externally extending flat pinch
seal at an end. It is particularly useful with tubular double-
ended incandescent lamps and heat lamps of the tungsten
halogen cycle kind utilizing fused silica envelopes. In such
lamps the inleads generally include extremely thin 1attened
ribbon or foil portions which are embedded in and sealed
through the wall of the fused silica envelope by collapsing
and fusing the silica firmly around the foil in a so-called
flat pinch seal. In use/ the lamp is generally supported by
accommodating the pinch seals at each end in spring metal
support clips ~ich may also serve as current connectors to
the inleads.
It has been the general practice up to now to pro-
vide a base terminal comprising a thin-walled metal sleeve
wrapped and clamped around the pinch seal to facilitate ~
accommodating the pinch seal in the spring support clip. In ~ -
one construction the base is connected to the externally
projecting portion of the inlead which then serves as a terminal.
In another construction a flexible pigtail is connected
to the inlead and the function o the base then is primarily
mechanical and decorative. Such base terminals are described
in United States patent 2,705,310 issued March 29, 1955 to
William F. ~odge, and comprise a flattened metal sleeve which
is stretched tightly around the pinch seal by folding or
welding together a seam along one side.
The mounting of bases of the foregoing kind on
the lamp ends is rather laborious and there is inevitably
some shrinkage by cracking of seal during assembly. The
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LD-6045
1061008Z
object of the invention is to provide an improved base struc-
ture serviceable also as a terminal, which is low in cost,
easily assembled, and reliable in service.
SU~MARY OF THE INVENTION
The invention provides a one-piece sheet metal base
for a tubular lamp having a pinch-sealed end which is adapted
to be simply pushed onto the lamp end by hand and frictional-
ly retained. It comprises a flat portion corresponding ap-
proximately in size to the flat side of the pinch seal, lon-
gitudinally extending upstanding wall portions on opposite
sides exceeding slightly in height the thickness of the pinch
seal and having inwardly turned underbeveled extensions which
resiliently grip the pinch seal for frictional retention. A
distal end wall portion has a forwardly turned extension or
lip adapted to overlie an externally projecting portion of
the inlead.
If the function of the base is simply mechanical
and decorative, a flexible pigtail is welded to the end of
the inlead and the distal end wall then covers up the weld
junction. The corners of the underbeveled extensions next
the end wall and those of the forwardly turned extension of
the end wall are preferably mitered to provide a passage for
threading the pigtail through the base. If the base is to
serve as a terminal in addition to its mechanical function,
the inlead is welded to the distal end wall.
DESCRIPTION OF DRAWING .
~ - -
In the drawing wherein like symbols denote cor-
responding parts in the several views: ;
FIG. 1 is an exploded perspective view of the ~ -
base and the end of the lamp on which it is to be accommo-
dated.
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106008Z LD 6045
FIG. 2 is a perspective view of a similar base
mounted on the opposite end of the lamp.
FIG. 3 illustrates a variant wherein the base
serves as electrical terminal
DETAILED DESCRIPTION
Referring to the drawing, there are shown the
ends of an electric liamp comprising a tubular elongated
vitreous envelope 1 through which extends a tungsten fila~
~ ment 2 connected at opposite ends to inlead conductors 3
having intermediate foil sections 4 hermetically sealed
through the vitreous material of the envelope in flattened ;
pinch seals 5. In an incandescent lamp for illumination
purposes, the envelope is generally made of clear, fused
sllica. For heat Lamps or sealed in~rared heatersj cheap-
~15 er translucent fused silica is commonly used. Quartz-like
glasses and other high temperature glasses may be substituted
for fused silica in applications of low~r heat stress.
The base 6 (or 6') according to the invention, -
- comprise~ a single piece of thin sheet material, suitably
stainless steel~ of which the main part is a flat portion
7 corresponding in size to the substantially flat pinch
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sea1. Ex~endin~g longitudinally along opposite sides of
the flat portion are upstanding wall portions 8 exceeding
slightly in height the thickness of the pinch seal and
~25 - having inwardly turned extensions 9 which are bent down or
downwardly inclined in order to resiliently grip the pinch `-
seal. In the preferred embodiment illustrated, the t~rned
over portions 9 form under~eveled rails angled down toward
j
~- the flat portion 7 of the base and adapted to frictionally
engage the pinch seal. An end wall portion 10 of less
.
height than the thickness of the pinch seal is provided at
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106008Z l.D (~ 0~15
the distal or outer end of the base. It includes a forward-
ly turned portion or lip ll adapted to abut the end of the
pinch seal and overlie the externally projecting portion 12
of the înlead conductor 3.
The end wall lO does not extend the full width of
the base whereby a gap or opening is left in each corner
which allows the egress of a flexible wire or pigtail 13
welded to inlead portion 12 to serve as a circuit connector.
The rear corners of rails 9 are mitered at 14 as are also
0 the corners of end wall lip ll at 15. The gap between the
mitered edges serves as a passage through which pigtail 13,
turned up as shown in FIG. l, may be threaded when the base
is pushed onto the end of the lamp.
Pinch se~ls may vary s,lightly in si e due to such -
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variables as tolerance~ in wall thickness of the original
fused silica tubing, the intensity setting of the sealing
fires, and th:e adjustment of the pinching jaws on the pinch
sealing machi~e. It is desirable to pinch the lamp end be- -
1 tween confined jaws so that the width of the pinch is in-
-~ variant. Accordingly the flat portion of the base is di-
~i~ mensioned to accommodate the width of the pinch between the
: wall8 8. Since the pinch width is a constant, tolerances in
silica wall thickness become variations in pinch thickness.
! ~- ` To accommodate such variations, wall portions 8 have a ~-
height exceeding the thicXest pinch seal which the toler-
~; ances permit. ~The underbeveled rails 9 are made wide enough
,~ and angled down so as to frictionally engage the thinnest
pinch seal which the tolerances permit. The partial miter
or rounding of the front corners of the rails at 16 is de-
sirable to facilitate the initial upward flexing of the
rails when pushing the base onto the pinch seal.
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LD 6045
1060082
The functions of base 6 illustrated in FIGS. 1
and 2 are primarily mechanical and decorative. It facili-
tates engage~ent of the lamp ends in the metal support clips
of the fixture~ The manufacturer's name or trademark may be
embossed or printed on the outside of flat portion 7 along -
with the lamp designation or rating, and the base gives a
finished appearance to the lamp. The distal end wall portion
10 serves as a shield over any sharp ends and covers the un-
sightly weld ~Jhere pigtail 13 is joined to inlead portion 12
FIG. 3 illustrates a variant o the invention where-
in base 6' serves as electrical terminal in addition to its
other functions. A central aperture is provided wi~hin end
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wall 10 and external portion 12 of the inlead is cut slight- . -: :
ly longer s~ as to project through the aparture. After-the
i 15 base is slipped over the pinch seal, the projecting portion
of the inlead is welded to the distal end wall at-17 so as
to make a low resistance connection. In this arrangement
base 6' serves as tha electrical terminal and the pigtail
, is eliminated.
20 ~ The im~roved base according to the invention is
readily pushed onto the pinch seal of electric lamps by
hand, and manufacturing experience shows that shrinkage
from the mounting operation is substantially eliminated.
The foregoing description of preferred species
is intended as illustrative of the invention only~ and -
the base and terminal structure may be modified within
.
, the spirit of the invention. I
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