Lamp capsule support base

A support for a filament or lamp capsule in a lamp having a base and a light-transmissive envelope includes a support ring that is inserted into the base. The ring can be pressed or otherwise secured into the base. The support ring includes at least one pair of tabs that extend radially inwardly. The tabs include mounting holes aligned generally in a direction extending upwardly from the base toward the envelope for receiving and supporting an electrical lead of the filament or lamp capsule. The tabs can be resilient to forcibly engage the lead of the filament or lamp capsule. Two pairs of tabs can be provided to support two leads of the filament or lamp capsule.

FIELD OF INVENTION 
This invention relates to electric lamps and, more particularly, to a 
support ring for a lamp capsule. 
BACKGROUND OF INVENTION 
It is common in the structure of high intensity lamps to utilize a 
pressurized inert gas filled capsule having a long filament and a pair of 
leads connected from the filament to the lamp base. A prior art lamp 20 is 
depicted in partially exposed perspective view in FIG. 1. The depicted 
lamp is used generally in commercial and retail settings to brightly 
illuminate a particular area such as store windows. A filament capsule 22 
is enclosed within a second larger translucent tubular outer envelope 24 
that is sealed to the base. The base 26 is a bayonet style cylindrical 
enclosure. The lamp 20 is common in European applications and is known as 
the T or BT style lamp. This lamp operates in the 220-250 range. The base 
is typically constructed of conductive metal, that electrically connects 
each of the capsule s conductive leads 28 to corresponding contacts in a 
light fixture socket (not shown). The leads 28 in this example comprise a 
pair of filament leads 29 that are electrically connected to a pair of 
base leads 31, which extend upwardly from the base 26 to a point just 
below the capsule. This configuration provides for easy attachment of the 
capsule to the base. 
It is important to position the capsule 22 appropriately within the light 
transmissive portion of the outer envelope 24. It is sometimes also 
important to position the capsule 22 with respect to base 26. In so 
positioning the capsule, it may be necessary to extend the leads 28. Since 
the leads are somewhat smaller in diameter relative to their lengths they 
may not have sufficient strength to support the weight of the capsule. 
Prior art capsule leads have been supported by surrounding them with a 
ceramic insert 30 (shown also individually in FIG. 2) that extends from 
the bottom of the lamp base 26 up to the lower end 32 of the capsule 22. 
The leads extend along inner, axially-disposed channels 34 in the insert 
30. The capsule 22 may be partially seated within preformed indents 36 at 
the top of the ceramic insert 30. These indents 36 may include recesses 
for receiving adhesive or cement to permanently seat the capsule in the 
insert. While the insert 30 satisfactorily isolates the leads 28 and 
supports the capsule 22, thus preventing bending and twisting of the 
capsule/lead structure within the lamp, the insert 30 adds substantial 
weight to the lamp and is prone to chipping from applied shock and 
vibration. The ceramic insert is also somewhat expensive due to high 
material and construction costs and, therefore, contributes to higher lamp 
construction costs. 
It is a general object of the present invention to provide improved capsule 
supports for lamps that utilize filament capsules. 
It is a further object of the present invention to provide a capsule 
support base, particularly adapted for use with sealed filament capsules, 
that is lower in weight and cost than conventional ceramic inserts and 
that exhibits durability equal to or greater than ceramic inserts. 
It is another object of this invention to provide a capsule support base 
that can be utilized with existing lamp components with minimal 
modification thereof. 
SUMMARY OF INVENTION 
A support for a filament or capsule in a lamp that includes a substantially 
cylindrical base and a light-transmissive envelope comprises a ring that 
is mountable within the base. The ring includes a outer diameter that is 
substantially equal to or slightly greater than a inner diameter of the 
base so that the ring may be installed in the base with its outer 
perimeter engaging an inner wall of the base. The ring includes at least 
one pair of supporting tabs that are directed radially inwardly from the 
outer perimeter of the ring. The pair of tabs can extend from opposing 
edges of the ring and can be positioned so that they are aligned with each 
other. Each tab includes a mounting hole for receiving an electrical lead 
of a filament or filament capsule. In particular, the tabs are positioned 
so that the filament lead extends from the lamp capsule through the holes 
in the tabs to the base. In this manner, the lead is supported along its 
length and is spaced from the sides of the base and the lamp envelope. 
The support ring can include two pairs of tabs for supporting two separate 
filament leads. These tabs can be positioned on opposite sides of the 
ring. The tabs can be spring loaded so that they bear with a spring force 
on the lead when it is positioned through the tab mounting holes.

DETAILED DESCRIPTION 
A lamp having a support base according to one embodiment of the invention 
is depicted in FIG. 3. A lamp 40 comprises a metallic base 42, a 
light-transmissive lamp envelope 44, typically constructed of glass, and 
an inner gas-filled capsule 46, typically of high temperature resistant 
glass or quartz, that encloses a high voltage filament 48. The capsule is 
supported in the envelope 44 by a pair of electrically conductive capsule 
leads 50 exiting its bottom end 52. The capsule leads 50 are connected to 
base leads 54, which are supported along their lengths by a supporting 
ring structure 53, positioned within a narrowed diameter portion 55 of the 
base 42. 
Unlike the prior art design of FIGS. 1 and 2, the bottom end 52 of the 
capsule 46 is not supported by a ceramic insert. Instead, each of the 
capsule leads 50 is electrically and mechanically interconnected with 
associated base lead 54 that provides full mechanical support for the 
capsule 46. Note that it is possible according to an alternative 
embodiment to provide a set of capsule leads that extend directly 
downwardly to the base 42 without an interconnecting set of base leads. 
The base leads 54 extend downwardly into the base 42 where they join with 
base-mounted electrical contacts 56, 58. As defined herein, "upwardly" and 
"downwardly" shall mean a direction that is coaxial with the lamp base and 
either extends "upwardly" from the base to the envelope or "downwardly" 
from the envelope to the base. 
Further details of the base are shown in FIG. 4. Each of the base leads 5 
is approximately 0.040-0.060 inches in diameter and is encased in an outer 
insulating tube 60 that adds rigidity to the structure and insulates the 
base lead wire 54 from the ring 53. The leads 54 are positioned 
substantially parallel and spaced from each other within the base 42. The 
ring 53 comprises a strip 62 of flat material that includes pairs of 
opposing tabs 64 that extend radially inwardly from upper and lower edges 
of the strip 62. The tabs 64 include holes 66 that are adapted to receive 
the base leads 54. The holes 66 are aligned axially to enable the base 
leads 54 to extend axially from the base to the capsule leads 50. 
The insulating tubes 60 in this embodiment can comprise rigid glass or 
ceramic material through which metallic conducting wire base lead 54 
passes. A tube outer diameter of approximately 0.060-0.080 inch is 
sufficient to provide good capsule support. Since the ring 53 according to 
this embodiment is metallic, the absence of the insulating tubes 60 would 
cause the wire base leads 54 to short circuit through the ring. The leads 
54 might also lack sufficient rigidity to prevent unacceptable sway and 
rotation of the capsule without the additional reinforcement provided by 
the tubes 60. The insulating tubes provide sufficient support to maintain 
the capsule 46 in an essentially fixed position relative to the lamp base 
42 and outer envelope 44. 
Note that it is contemplated according to this invention to incorporate an 
insulator directly into the ring 53, thus eliminating the need for an 
insulator such as the tubes 60 around the leads 54. Such insulation could 
include a nonconductive coating on all or part of the ring where it 
contacts current carrying conductive elements. 
The ring 53 according to this embodiment is constructed of a somewhat 
flexible metal that is elastically deformable under predetermined loading. 
A beryllium copper alloy can be utilized for the ring 53 according to this 
embodiment. The ring can be formed from a flat piece of sheet material 
that is stamped to include the supporting tabs as opposing projections 
from the upper and lower edges of an otherwise rectangular strip. The 
strip of sheet material is then formed into a ring and joined at its ends 
to provide the ring structure. Joining can be accomplished by a variety of 
methods, including soldering, swaging or other conventional metal joining 
techniques. The tabs are then folded along a line with the ring edges 57 
to project radially inwardly, thereby providing the ring support 
structure. 
A somewhat resilient ring 53 material is used to maintain pressure against 
the insulating tubes 60 for retention of insulating tubes 60. As the tubes 
60 are inserted into the ring tabs, the tabs are deformed into positions 
in which they are essentially parallel to each other and as depicted in 
FIG. 5. This allows resistance free sliding of the tubes 60 into the holes 
66. The tabs expand outwardly from each other when they are released. The 
holes 66 are closely matched in diameter to the outer diameters of the 
tubes 60. Thus, as the tabs 64 spread out, they engage the tubes 60. In 
this configuration, the tabs 64 bear against the sides of each tube 60 and 
frictionally prevent it from moving out of position relative to the ring 
53. Thus, no adhesives or other supplemental attachment means are required 
to maintain the tubes 60 in position relative to the tabs or the ring. The 
tubes should be sized slightly less in outer diameter than the inner 
diameter of the tab holes. In this manner, a strong retention force is 
exerted by the tabs. After leads 54 are attached to the base contact 56, 
58, such as by soldering, the assembly is better able to resist axial 
forces, because the attached leads 54 cooperate with the tabs 64. 
The outer diameter of the ring 53 is sized to closely match the inner 
diameter of the lamp base 42. The ring 53 is securely inserted into the 
lower, narrowed diameter, portion 55 of the base 46. Following insertion 
of the ring 53 into the base 42, the ring 53 can be permanently joined to 
the base 42 by a variety of methods. In this embodiment, the ring 53 
includes a pair of radially inwardly directed folds 68 positioned at 
90.degree. angles along the ring 53 from the tabs 64. The outer diameter 
of the ring 53 including the folds 68 is, as stated, sized to securely 
enrage the inner diameter of the lower portion 55 of the lamp base 42. 
When the ring 53 is properly positioned within the base 42, one or both of 
the folds 68 can be crimped radially outwardly toward the inner wall of 
the lamp base 42. This crimping can be accomplished by means of jaws that 
engage the fold 68 and outer wall of the base or, alternatively, by means 
of expanding jaws positioned within the base 42 that extend outwardly 
toward the opposing folds 68. The "flattening" of the folds against the 
base 42 walls causes an increase in the ring s free diameter which results 
in a corresponding radially outward force in the ring 53 as it bears upon 
the inner wall of the base 42. This force significantly increases the 
contact pressure between the ring and the base, resulting in a strong 
interfering frictional fit (press fit) between the ring 53 and the lamp 
base 42. 
While a press fit between the ring 53 and base 42 is achieved according to 
this embodiment by utilizing crimped folds 68, it is equally possible to 
secure the ring 53 to the base 42, using an unfolded press fit ring of 
slightly larger fixed outer diameter than the base inner diameter that is 
forcibly driven vertically into the base 42 causing an interference fit 
therebetween. Alternatively, a ring having little or no interference fit 
can be attached to the base by inserting it into the base 42 and 
subsequently spot welding or soldering the components together. 
While the embodiment of the invention shown in FIGS. 3-6 employs two pairs 
of tabs 64 for mounting two base leads 54, it may be preferred for certain 
applications to provide a support ring with only one pair of lead support 
tabs. A support base structure and ring 70 having only one pair of 
supporting tabs 64 is depicted generally in FIGS. 7-9. This single 
lead-type construction might find application for lamps known as "double 
end" types, which have one lead at each end. For standard size filament 
capsules having, for example, an 11 mm outer diameter and for capsules 
having short leads that do not extend substantially into the base 42, it 
has been found that a single support lead 72 is sufficient to provide 
adequate support for the lamp capsule. Lamps with longer leads and larger 
capsules may still require two pairs of supporting tabs, but most 
conventionally-sized lamps of the type contemplated herein require only 
one lead to be supported, while the second lead (not shown, but which may 
comprise separate capsule and base lead portions) extends to the base 
contact without additional support thereof. 
The support ring 70, having only one pair of tabs 64 according to this 
embodiment, is firmly attached to the base 42 by a variety of fastening 
methods, which may include crimpable folds 68. The support tabs 64 are 
deformed toward each other but have sufficient resilience to firmly engage 
the insulator tube 76. In the single tab pair embodiment, the unsupported 
lead and its connections (not shown) must have sufficient tensile strength 
to resist stretching and breakage. Otherwise, the filament capsule may 
tend to rotate about the supported lead in absence of an anchoring force 
exerted by the unsupported lead. 
The preferred single tab pair embodiment shown in FIGS. 7-9 is even less 
expensive and simpler to manufacture than the double tab pair embodiment 
of FIGS. 3-6. Additionally, the complete lamp utilizing a ring according 
to this embodiment is more quickly and less expensively manufactured than 
prior art lamps, since only a single support tube lead assembly must be 
constructed. 
It should be understood that the preceding is merely a detailed description 
of possible embodiments. It should be apparent to those skilled in the art 
that various modifications and equivalents may be made without departing 
from the spirit or scope of the invention. The preceding description is 
meant, therefore, to be taken only by way of example and not to otherwise 
limit the scope of the invention.