Improvements in Electric Lamp Holders.
Year: 1899

page_text: Date of Application, 23rd Mar., 1899-Accepted, 29th Apr., 1899
Improvements in Electric Lamp Holders.
I, ROBERT FREDERICK HALL, of Ferndale, Church Road, Moseley, near the City
of Birmingham, 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:-
Hitherto the electrical connections of the flexible circuit wires to incandescent
electric lamps have been defective from such causes as insufficient contact and
liability to short circuiting through strands of wire of opposite poles coming in
contact and through the brass or outside metal casing coming in contact with
the poles through the medium of projecting screw heads, loose strands of wire and
the like, and from similar causes.
The object of this invention is to overcome such defects and make an improved
and effective contact between the lead or circuit wire and the lamp terminals or
contact pieces by the employment of a joint or connection in the form of a nipple
of suitable shape, of which a pair are employed respectively secured to the positive
and negative lead or circuit wires and inserted into separate holes or sinkings
formed within a block of porcelain or other suitable non-conducting material in
such a manner that each nipple or connection is completely enveloped in non-
conducting material and is thus perfectly insulated from the other. This porce-
lain body part is inserted within the metallic body part of a lamp holder and
secured there and prevented from rotating by suitable means.
Figure 1 of the accompanying drawings represents an elevation of an electric
lamp holder embodying my improvements.
Figure 2 is a topside plan of the same and Figure 3 an underside plan.
Figure 4 is a complete vertical section of the said lamp holder, showing the
internal arrangements.
Figure 5 is a cross section of Figure upon the dotted line and clearly
represents how the pairs of nipples, to which the lead wires are connected and
which are fitted with the contacts for the lamp terminals, are embedded or located
within separate holes in a block of non-conducting material and are thereby
insulated one from the other.
Figure 6 represents the pair of nipples and contact pieces, with their circuit
wires attached, separately and in elevation.
Figures 7 and 8 represent in section, the two screwed together parts of the
casing separated. By the screwing together of these parts when the whole of
the elements of the holder have been assembled, the conical cord grip (shown in
section and top plan separately in Figures 9 and 10) is drawn down upon the
insulating body part (shown separately but with the nipples in position in
Figures 11 and 12) and the lead wires are gripped between the inside of the former
and a conical projection on the top of the latter, thereby at the same time securing
the said nipples and their contact pieces in position.
Figure 13 is a topside plan of the principal part of the outer casing.

page_text: Figures 14 and 15 show a section and a plan of the lamp-shape locking ring,
which screws onto the casing and clamps the shade to the holder.
The same letters of reference indicate corresponding parts in the several
figures of the drawings.
a is the open ended outer casing of the lamp holder, having bayonet gaps a¹,
formed in the edges of the lower open end with which the usual projections on
the lamp engage, whilst fitting within the upper part of the said casing (which
is preferably made of brass or other metal) and resting upon the inside shoulder a²,
thereof, is a block b, made of porcelain or other non-conducting material, having
formed within it, a pair of separated sinkings 61, 62, which are of a depth nearly
equal to the thickness of their blocks and have holes 63, 64, through their bottom's
whilst they are separated from one another by an intervening wall b'.
Located within the said sinkings are a pair of nipples c, connected respectively
with the flexible positive and negative lead wires d, and carrying also the spring
contact pieces e, which comes against the terminals of the lamp filament when
the said lamp is in position. Each nipple may be formed from round metal rod
and has a flat c³, machined at the upper part, which is thus made of a D-shape
in cross section, and into it is drilled a small hole ³, proceeding from a circular
recess ³, in the face of the flat and forming a receptacle for the end of the lead
wire which is preferably bent into a loop or eye, for a binding screw pin c
to take through and when tightened up. to bury the said wire within the said
recess and clamp it against the face of the nipple, thereby forming a perfect
electrical connection between the said parts, not liable to corrosion or other fault.
By making the upper part of the nipple with a flat face or D-sectioned room is
provided for the location of the head of the screw within the circle of which the
D-part forms a half, thereby admitting of the said nipples with their contact
pieces, being respectively inserted within the separated sinkings 1, 2, in such
a manner that each is completely enveloped in non-conducting material and
perfect insulation of the one from the other and of the nipples from the walls of
the outer casing. The lower end of each nipple is outside screwed at c³ and bored
out at co, to receive the upper end of a sliding and hollow contact piece e, which
works within the said recess c, and has in conjunction with it, an internally
located spring e¹, whilst the said contract piece is connected with the said nipple
by a union rings, screwing upon the part c and having a flange e", against which
the slightly enlarged inner end e, of the contact piece comes and is thereby
confined to the nipple. The contact pieces extend through the holes b', 6', in
the bottoms of the sinkings 61, 62, into suitable positions below the insulation
block for coming against the terminal plates of the lamp filament.
66
Upon the top of the insulation block is a conical extension f, located between
the nipple sinkings b', 63, and channelled upon the opposite sides at fl, f, to
receive the lead wires or cords," which are gripped (and thereby held against
twisting or displacement) between the said extension and an inside coned cap g,
made of insulating material and placed onto the said projection. with gaps or
notches at 93, 9³, opposite to the channels f, f, for the cords to lie within and
a hole g, at the top end through which the said cords pass away from the holder.
This cord-gripping cap is drawn down onto and around the cords, and the parts
of the holder incidentally retained in their assigned positions, by a union a³,
the lower mouth end of which is inside wormed to screw upon the metal casing a,
whilst its upper and flanged or contracted end at, bears upon the edges of the said
cap and exerts an equal downward pressure upon it when screwed home. The
rotation of the insulation block b, within the holder may be prevented by impress-
ing inwards portions as of the metallic walls of the former to take within vertical
grooves 6', in the opposite sides of the latter.
h is the shade securing ring adapted to also screw onto the outer casing of the
holder and clamp the shape of the lamp between it and the lower edge of the
union a³.
By constructing and arranging the parts of a lamp holder in manner 29

page_text: described, perfect insulation is obtained and the grip upon the cords or lead
wires is so firm that the weight of the lamp with its holder and shape may be
entrusted to them with safety.
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:-
First In electric lamp holders, the employment of metallic nipples or
equivalent end fittings, to which the ends of the circuit or lead wires are secured
and which carry attached spring plungers adapted to contact with the filament
terminals of the lamp, substantially as described and set forth.
Secondly: A nipple or lead wire end attachment for electric lamp holders,
having a flat face at the upper part recessed to receive the naked wire end which
is affixed by a screw, and with the casing of a spring plunger or contact piece
connected to the body part of the said nipple by a union ring or screw, sub-
stantially as described and set forth.
Thirdly: In electric lamp holders the combination with a block of insulating
material located within the casing and provided with a pair of separated sinkings
or holes, of a pair of lead wire nipples with attached contact pieces or plungers,
the upper parts of each nipple being of a D section or having a flat face to provide
for the location of the head of the lead wire binding screw within the circum-
ference of the nipple, substantially as and for the purpose described and set forth.
Fourthly: In electric lamp holders, the employment in conjunction with an
internal block of non-conducting material having a conical projection upon its
top side, of an inside-coned cord-grip cap, also made of non-conducting material
and arranged and secured substantially as described and set forth.
Dated this 22nd dow of March 1000
ROBERT FREDERICK HALL,
By Henry Skerrett,
24, Temple Row, Birmingham, Agent for Applicant.