Improvements in Electric Incandescent Lamps.
Year: 1899

page_text: Improvements in Electric Incandescent Lamps.
I, CHARLES HOWARD, of 11, Charing Cross Road, London, in the County of
Middlesex, Electrical Engineer, do hereby declare the nature of this invention and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:-
This invention relates to improvements in electric incandescent lamps and has for
its chief object to provide a lamp which can be repaired in a very simple and
inexpensive manner after the filament has become broken or worn out, and one of the
main features of my invention consists in the improved fastening of the metallic cap
or base on the lamp bulb.
According to my present invention the lamp bulb is formed with an elongated
tubular neck which is blown in one with the bulb. In a lamp of this class it is
essential that an easily removable cap or base should be provided on the lamp bulb,
as if the ordinary cemented caps were used there would be great danger of the
connections or joints being destroyed, and the cement also being injured, by the
heat employed in rejoining the neck and bulb. With my invention I provide for a
very simple and effective fastening of the cap or base on the lamp bulb without the
use of the ordinary cement as now usually employed, and without the use of a wire
or the like.
In the construction of the lamp the ordinary filament is attached (in any convenient
or well known manner) to elongated terminal wires connected to the usual insulated
terminal strips or plates fitted in the cap (or to the cap itself), such elongated wires
being necessary owing to the length of the tubular neck on the lamp bulb. When
the lamp is required to be renewed the elongated neck is cut or divided (by means of
a red hot wire or otherwise), the broken filament is removed and a new filament
attached direct on to the above mentioned elongated terminal wires by means of any
suitable or well known cement, the bulb being then fused on to the neck and
exhausted in the usual manner when the lamp will again be ready for use.
In order that my invention may be more clearly understood and readily carried
into effect I will now describe it with reference to the accompanying drawings, in
which:-
Figure 1 is an elevation of a lamp according to my present invention, the cap in
this figure being adapted to fit in the lampholder or socket by means of the usual
bayonet joint.
Figure 2 is a plan of same shewing the insulated terminal plates and terminal
wires.
Figure 3 is a sectional elevation on an enlarged scale shewing my special means for
attaching the cap to the lamp bulb.
Figure 4 is a sectional plan of Figure 3 on line A A.
Figures 5 and 6 illustrate the metal discs or plates hereinafter referred to.
The same letters refer to the same narts in the several figures

page_text: a is the lamp bulb provided with the elongated tubular neck a¹. The main
object in making the lamp bulb in this way is that owing to the length of the
neck a¹ and its comparatively small diameter it can be readily separated or
cracked (as herein before described) and readily refused to the bulb, after the new
filament has been inserted, without injuring the terminal wires where they pass
through the glass. 6 b₁ are the elongated terminal wires and c is the filament
attached to said wires by means of suitable cement. The top or end of the
elongated neck a¹ is formed with circular recesses or indentations & d¹ on opposite
sides thereof, also a bead or shoulder e. Holes f f¹ are provided in the cap g at opposite
sides, which holes correspond with but are preferably smaller than the recesses d d¹
in the neck a¹. h h¹ are plates or discs of suitable metal which fit in the recesses or
pockets d d said plates being for the purpose of protecting the glass from
solder (or other suitable molten material) which is dropped through the holes ƒ ƒ¹
in cap g (after the latter has been placed in position on neck a¹) so as to fill the
recesses à d¹ in the neck a¹ and protrude slightly through the holes f f¹ in cap g
so as to form small knobs or projections on the outside of the cap when the
solder sets. The solder in recesses d d¹ in the neck a! and projecting through
holes ffin cap g forms a plug or key which securely holds said cap on the
bulb neck a¹ by cutting off or removing the knobs of solder (j j¹ Figs. 1 and 2) the
cap g can be readily removed from the neck a¹ and it can of course be easily fastened
on again by means of solder as herein before described.
Figure 4, are the terminal plates in the cap g and k¹ is the insulating material
in which said terminal plates are set. *
Assuming that the filament of the lamp broken and that it is desired to replace
it by a new one, it is only necessary to crack the glass around the tubular part or
neck of the lamp at a suitable point such as a² (Fig. 1) then withdraw the
damaged filament and reinsert a new filament joining said new filament direct to
the elongated terminal wires b b¹ by means of a suitable cement and then refuse the
bulb on to the neck a¹. The lamp can be exhausted in any convenient manner and
will then be ready for use again.
If any damage has occurred to the connections at the closed end of the neck a¹
the cap g can be readily removed, as herein before described, the connections made
good and the cap replaced again and fastened on the neck a¹ by refilling recesses d d¹
in said neck and holes ff' in the cap with solder or the like.
Although I have described the recesses d d¹ in the neck of the bulb as circular
recesses yet they might be square or of other suitable shape, but they are such that
the plug or key of solder or the like will be securely retained therein and will firmly
hold the cap g on the neck of the bulb, thus providing a simpler and better fastening
than that wherein a wire is employed for holding on such caps.
Although I have illustrated a cap on the lamp bulb adapted to fit in the socket by
means of the usual bayonet joint yet my improvements are applicable in connection
with screwed or other forms of caps.
Having now particularly described and ascertained the nature of my said inven.
tion and in what manner the same is to be performed I declare that what I
claim is
1. In an electric incandescent lamp the combination of a bulb having an elongated
tubular neck, recesses or indentations (as d d¹) in said neck, elongated circuit
terminal wires fused in said neck, a filament cemented on said elongated terminal
wires, a cap provided with holes (as ff¹), plugs or keys of solder or the like engaging
the recesses in the neck of the bulb and holes in the cap, and means for preventing
injury to the glass on the insertion of said plugs, all substantially as and for the
purposes set forth.
2. The herein described means for fastening the cap on an electric incandescent
lamp by plugs formed of solder or other material engaging recesses in the neck of the
lamp and corresponding holes in said cap, substantially as herein set forth.

page_text: 3. In electric incandescent lamps the method of renewing the filaments by
cutting or opening the lamps at the elongated tubular neck, inserting a new filament
and cementing same to the existing terminal wires, refusing the bulb to the elongated
tubular neck and exhausting same: substantially as described.
1000
JOHN P. O'DONNELL, Fel. Chart. Inst. P. A.,
Agent for Applicant, 70 & 71, Palace Chambers, Westminster, S.W.