Improvements in Electric Lamp Holders.
Year: 1897

page_text: Date of Application, 9th Dec., 1897-Accepted, 15th Jan., 1898
Improvements in Electric Lamp Holders.
"
I, EDWARD LIONEL JOSEPH, of 92 Queen Victoria Street, in the City of London,
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, and accompanying drawing, that is to say:--
My present invention relates to the holders used for incandescent electric lamps,
in which the neck of the lamp is provided with a bayonet" joint by which it
can be easily and quickly attached to, or removed from the holder by which it is
carried, which is provided with the corresponding part of the bayonet joint. In
such holders provision is made by which, when the lamp is fixed in its place, the
terminals connected with the filament which is to be made incandescent are
brought automatically, by the action of attaching the lamp to the holder, into
secure electric contact with the insulated poles of the conducting wires in the
latter. For this purpose, it is usual to fit in the lower end of the holder a disc
of suitable insulating material to the lower side of which are screwed two metal
sockets containing spring plungers or contact pieces, which project downward and
are arranged in such a position that by the action of fixing the lamp in its place
the terminals in its neck press against and make perfect metallic electric contact
with the spring plunger.
Each of the metal sockets is connected with one of the insulated conducting wires,
which are passed down through the upper part of the holder.
It is essential that the two sockets, with the metal parts connected with them,
and the conducting wires, should be absolutely insulated from each other and from
the metallic chamber in which they are fitted, without the possibility of their
coming in contact, and different methods of ensuring this absolute insulation may
he employed.
My present invention has for its object a novel method of construction and
arrangment, by which not only perfect and constant insulation is effected, but the
entire device is exceedingly simple, cheap, durable, and very easily put together
and taken apart when necessary.
For this purpose I use a plate, cylinder, or block, of porcelain or other suitable
insulating material, of such diameter as to fit. freely within the inside of the lamp-
holder, a short distance above the angular notches which form part of the bayonet
joint by which the lamp is attached. The upper end of the insulating porcelain
cylinder or block is provided with a flange of somewhat larger diameter which fits
freely in a corresponding recess at the upper part of the holder, and above the
flange is a hollow, bell-shaped tube, the lower expanded edge of which rests upon
the flange of the insulating cylinder, and is held against it by a hollow nut which
is passed up from below and is screwed upon the outer edge of the bell-shaped tube
described.
The metallic spring plungers or contact-pieces are fitted in spaces made for them
in the insulating cylinder or block, and the insulated conducting wires are screwed
to their upper ends and led away through the bell-shaped top. "The lower ends of

page_text: the spring contact pieces are protruded for a sufficient distance below the lower end
of the insulating cylinder.
In order that the spring contact pieces may be automatically arranged and held
in their proper places in the insulating cylinder, I make this cylinder in two parts,
separated by a vertical plane passing through the centre of the cylinder, and in
each such half, I make a recess fitted to receive freely half of the spring plunger or
contact piece, the other half of which is contained in a corresponding recess in
the other or alternate half of the insulating cylinder. The lower ends of the
recesses are of a diameter only sufficient to allow the spring contact plunger to
protrude, and their upper ends are only large enough to allow the insulated wire
which is connected to the contact piece to pass up into the hell-mouthed top. The
ends of these insulated wires are fixed in the contact pieces by means of screws,
the heads of which lie in recesses in the insulating cylinder or block, one of such
recesses being preferably in each half of the cylinder.
The accompanying drawing is in illustration of my invention.
Figure 1 is a side view of the entire holder. Figure 2 is a vertical section
through Figure 1, Figure 3 is a view of Figure 1 from above, and Figure 6 a view
from below. Figure 4 is a view from above of the two halves of the insulating
cylinder fitted together, Figure 5 is a horizontal section through the two separated
halves of the insulating cylinder. Figure 7 shows side views of the spring contact
pieces.
a is the insulating cylinder or block, fitting freely in a recess in the lower part
of the cylindrical holder b, which is provided with notches c, c¹ to form the bayonet
joint for attaching an incandescent lamp. The insulating cylinder a is shown
with a flange d near its upper end, which is screwed up against the lower end of
the bell-mouthed top e, by means of the hollow nut f. The insulating cylinder a
is made in two halves (as shown in Figures 4 and 5), each of which contains half
of the recesses g to contain the spring contact pieces h, h (shown separately in
Figure 7), into which the ends of the insulated conducting wires are fixed by
screws,, the heads of which lie in recesses in the halves of the insulating block a.
The insulated conducting wires (which are not shown in the drawing) pass up
through small holes k, k, in the upper end of the block a, and then pass out through
the bell-mouthed top c
The two halves of the insulating block, are kept in their proper place by a
notch at fitting over a projection m (Figure 8) on the holder b. Instead of the
two halves being flat where they are in contact, one of them may have a projection
(between the recesses) fitting into a corresponding notch in the other half."
When the spring contact pieces h. h. with the insulated conducting wires
attached to them have been fitted in the recesses g, q in the block a, the two halves
of the latter are held together and inserted from above into the upper end of the
holder b, and all the parts are securely and firmly held together by screwing the
nut upon the top e.
This can be very easily and quickly effected, and the lamp holder can be equally
Pasily taken apart when desired.
The whole device is very simple, cheap, durable, and effective, and metallic
contact between the conducting wires and the parts connected with them is
impossible.
I do not confine myself to the precise details of shape and proportion, and of
construction, which may be varied to suit varying circumstances, but
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is;-
In electric lamp-holders, the separate insulating cylinder a, made in two halves.
and fitting in the holder, recesses being made in the two halves of the insulating
cylinder to receivo and enclose the spring contacts h.h, the holding screws of

page_text: which i, i, fit in supplementary recesses in the insulator a, the insulated con-
ducting wires passing out through smaller holes k, k, in the insulator a, and the
spring plungers of the contact pieces h, h, passing down through holes in the
lower side of the insulator a, substantially as and for the purposes described and
illustrated.
Dated this 9th day of December 10.
EDWARDS & Co.,
65 and 66, Chancery Lane, London, Agents for the Applicant.