Improvements in Moderating Electric Incandescent Lamps, and Apparatus for that Purpose.
Year: 1896

page_text: Date of Application, 18th Mar., 1896
Complete Specification Left, 18th ec., 1896-Accepted, 30th Jan., 1397
PROVISIONAL SPECIFICATION.
Improvements in Moderating Electric Incandescent Lamps, and
Apparatus for that Purpose.
GODFREY BAMBERG Chemist 33 Barcombe Avenue Streatham Hill S.W.
do hereby declare the nature of this invention to be as follows:-
The object of this invention is to provide in the electric incandescent lamp and
current leading apparatus an improved means of reducing the normal intensity of
the light with a corresponding reduction in the flow of current, the same voltage
being maintained and only one filament suitably arranged being used.
The intensity of the light can be reduced by known method of inserting a
resistance or choking coil in the leads but the reduction in the flow of current is
not proportionate to the reduction in the light given and is therefore of little
practical use, and though arrangement of two filaments of different resistances with
a bar in the collar of the lamp sending current through one or other of the filaments
can be made, the great difficulty of getting at the collar of the lamp, when the
lamp is in the customary shades renders this method objectionable and only one
lamp at a time can be moderated.
But by this invention the lamp can be lowered at a proportionate reduction of
current and using only one filament and by a key holder having the customary
external arrangement and outside of the shade, or a series of lights can be reduced
by a switch at a distance from the lamps.
In carrying out my invention, I provide a third external terminal, by preference
in the centre of the base of the brass collar, which together with the usual two side
terminal plates will connect, when the lamp is in the socket, to three spring contacts
placed at equal distances across the diameter of the socket and insulated from each
other. The filament, while flexible, previously to being carbonised is bent double
and at about half of the doubled length reckoning from the bend it is twisted
either as a double helix or as a twist and a loop and the two free ends bent back
so that the twisted or looped part is in the centre of the two ends, and the filament
is then carbonised. If current be sent from one end to the other, the twisted part
would be short circuited and would not glow but if current be sent from the bent
end through the twist the two ends being joined to the opposite lead both the
central twist and the outer ends will glow requiring double the current and giving
double the light.
To effect this, the two ends are connected by the usual platinum wires in the
vacuum globe with the two usual side terminal plates in the base of the lamp
collar, while the central lower end of the twisted part of the filament, or the
middle of the loop is connected to the third or central terminal plate by another
platinum wire, thus affording a way of sending the current in at the central and
out at the two side terminal plates, or sending a current from one side terminal
plate to the other, and the centre not being connected to the leads the twist or
loop is short circuited, the change of direction of current being effected by a com-
mutating key switch hereinafter described. By arranging the filament so that the
outer part consists of two or more twists and the outer ends have the bends, while
the inner part is a free untwisted end, lamps with various desired degrees of
difference in light when turned down can be made.

page_text: The socket into which the lamp fits has the three spring contacts which go
through the insulating base, and each may terminate in a bifurcated engaging
piece into which when in certain positions, pieces of brass on the commutating key
switch will fit. Below the key are two screw contact plates for connecting with
the two leads, from each of which plates rise two engaging bifurcated pieces
suitably placed so as to connect through the brass pieces on the key and thence
through the spring contacts into the lamp.
-
The brass pieces inserted into the key, which key is of insulating material, are
two of them in the shape of a quarter of a circle the third being about a semicircle.
When the key is upright, one quarter circle connects one outer terminal with
the lead, and one quarter circle connects the centre terminal with the + lead,
and the semicircle connects the other outer terminal to lead, thus sending the
current in at the central terminal and out at the side terminals and causing the
whole of the filament to glow, while if the key is in horizontal position, the first
quarter circle becomes connected to + lead, the second quarter circle disconnected
and the semicircle connected to lead, thus sending the current in at one outer
terminal and out at the other outer terminal short circuiting the central twist or
loop so that only the outer part of the filament glows, while if the key is placed
perpendicular to first position all spring contacts are disconnected.
-
Obviously the bifurcated pieces could be on the key and only projecting pieces
on the spring contacts and continuations of screw contact plates of the respective
leads, or bifurcated pieces on all. If three wire system be used as far as switch,
a whole series of lights may be lowered or raised at once, the switch of course being
commutating in manner hereinbefore described.
Dated this 18th day of March 1896.
GODFREY BAMBERG.
Improvements in Moderating Electric Incandescent Lamps, and
Apparatus for that Purpose.
1, GODFREY BAMBERG, of 33 Barcombe Avenue, Streatham Hill, London, 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 :-
The object of this invention is to provide in the electric incandescent lamp and
current leading apparatus an improved means of reducing the normal intensity of
the light with a corresponding reduction in the flow of current the same voltage
being maintained and only what may be termed one filament suitably arranged
being used.
The intensity of the light can be reduced by known method of inserting a
resistance or choking coil in the leads but the reduction in the flow of current is
not proportionate to the reduction in the light given and is therefore of little
practical use, and although an arrangement of two filaments of different resistances
with a bar in the collar of the lamp sending current through one or the other of
the filaments can be made, the great difficulty of getting at the collar of the lamp
when the lamp is in the customary shades renders this method objectionable, and
only one lamp at a time can be moderated.
Now by this invention the lamp can be lowered at a proportionate reduction of
current and using only one filament and by a key holder having the customary
external arrangement and outside of the shade, or a series of lamps can be reduced
at a distance from the lamps.

page_text: My invention will be understood by referring to the accompanying sheet of
drawings in which
Figure 1 is a part perspective view of the lamp with my improved form of
ilament suitably arranged in connection with three contacts in the collar of the
lamp.
Figure 2 is a side elevational view of the lamp socket into which the lamp is
fitted when in use, the, particular construction and arrangement of the parts of
said socket being shown in detail by Figures 3, 4, 5, 6, 7 and 8 respectively.
Figures 9, 10, 11, 12, 13, 14 are views illustrating some of the many forms of
filaments that may be adopted, all being arranged with three terminal ends.
Figures 15, 16, 17, and 18 are diagrams clearly illustrating the manner in which
the leading in current is commuted to either the centre, or one of the sides of the
filament as well as cutting said filament out of the circuit altogether.
Figure 19 is a sectional elevation of a commutator switch of similar construction
as required when it is desired to control a number of lamps from a single switch.
In carrying out my invention, I provide a third external terminal A by preference
in the centre of the base of the brass collar B which together with the usual two
side terminal plates C, D, will connect when the lamp is in the socket to three
spring contacts E, F, G, Figure 6, placed at equal distances across the diameter of
the socket and insulated from each other by the material H to which they are fixed.
The filament a while flexible previously to being carbonised is bent double and at
about half of the doubled length reckoning from the bend it is twisted either as a
double helix or as a twist and a loop and the two free ends bent back, so that the
twisted or looped part is in the centre J of the two ends K, L, as at Figures 1, 9,
and 15, and the filament is then carbonised.
If current be sent from one end, say K, to the other end I, the twisted or middle
part J would be short circuited and would not glow, but if current be sent from
the bent end J through the twist, the two outer ends K, L, being joined to opposite
lead, both the central twist and the outer ends will glow, requiring double the
current and giving double the light. To effect this, the two ends K, L, are
connected by the usual platinum wires K', L', in the vacuum globe with the two
usual side terminal plates C, D, in the base of the lamp collar, while the central
lower end of the twisted or looped part J of the filament is connected to the third
or central terminal plate A by another platinum wire A', thus affording a means of
sending the current in at the central, and out at the two side terminal plates, or
sending a current from one side terminal plate to the other, and the centre not
being connected to the leads, the twist or loop is short circuited, the change of
direction of current being effected by a commutating key switch hereinafter
described.
By arranging the filament so that the outer part consists of twisted parts and
the outer parts have bends, while the inner part is a free untwisted end, lamps
with various degrees of difference in light when turned down can be made. The
socket into which the lamp fits has the three spring contacts E, F, G, before-
mentioned, which go.through the insulating base H, and each is in connection with
the brushes E, F, and G', respectively, as can be plainly seen upon reference to
Figure 7 of the drawings. The leading in wires are connected to the holder by
the screws M, N.
The spring contacts E, F, G, and insulating base H, illustrated in Figure 6, are
adapted to fit in the socket H (Figure 3) and secured by cap H³ for the brushes
to embrace the commutator P, said commutator being fitted with contact
plates Q, Q', upon opposite sides thereof, as indicated in Figure 4, whereby the
inflowing current can be commuted to cause it to flow in the required direction
through the filament, as will be gathered upon reference to the diagrams
Figures 15, 16, 17, and 18, the terminals of which are lettered to correspond with
the brushes and contacts of Figures 5, 6, and 7, while the commutator is for the
purpose of illustration only shown of such form as will convey a clear idea of the
.operation.

page_text: In Figure 15, the commutator connects the positive terminal M with the
terminal or brush F, and the terminals or brushes E, G, with the - terminal N.
thus causing current to enter the middle loop and pass up the two sides causing
the whole filament to glow.
In Figure 16, by a quarter turn of the key P, the positive terminal M is
connected by the commutator P to the terminal or brush G¹ and the terminal N
with the terminal E, the central terminal F being disconnected altogether, con-
sequently the middle loop is short circuited, and the current flows only through
the outer limbs of the filament thus giving less light.
In Figures 17 and 18, the circuit is not complete in either instance, consequently
when the key is turned in either of these positions, the filament will not glow
at all.
Instead of the three spring plunger socket previously described, it is obvious the
ordinary two plunger socket can be used and the other lead connected to the
holder and collar of lamp but the before described method is preferred.
The filament while flexible may, previously to being carbonised, be bent double
and at about half of the doubled length reckoning from the bend it is twisted
either as a double helix, or as a simple twist to make a joint at J, Figure 9 and
the remainder until the bend as a loop, and the two free ends bent back, so that
the twisted or looped part is in the centre of the two ends and which centre at the
bend now forme a third end for the inlet or outlet of current and the filament is
carbonised, this amounts to a filament which is in the form of a T, the horizontal
part of which is bent back to form together with the vertical portion the three ends
and for convenience of manufacture in some cases I join two carbonised filaments
into one piece into the form of a T by usual carbon paste and flashing and then
bend them, back forming filaments as shown in Figures 10 and 11.
The horizontal part or two sides may be of different resistance and length
compared to the vertical part or central part according to the varied conditions
requiring different proportions of light when moderated or full on..
If the horizontal part, (that is the two sides) is four times the resistance of the
vertical (that is the central) part, as in Figure 10, the light may be moderated to
half, but the horizontal part may form the low resistance, and the vertical part the
high resistance, as in Figure 11, or the filament may be made of various
resistances for various other proportions of light.
If current in the first instance by the arrangement in the holder hereinbefore
described be sent from one outer end of filament to the other outer end and centre
disconnected only the high resistance outside filament glows while if current be
sent in at the centre and out at the two other ends, the whole of the filament glows,
and as in this case the joint resistance is only half that when sent from one outer
end to the other outer end, twice the current flows and the candle power is also
doubled.
In the second instance, the outer portion of the filament being of low resistance,
the full candle power and largest flow of current takes place when the current
enters one outer end and leaves by the other outer end, the centre being dis-
connected, while if current be sent in at centre and out at the two outer ends, the
centre being of high resistance, only the centre filament glows since only a small
current can be sent through this high resistance, the low resistance outer filament
acting as conductors only, without glowing.
In my Provisional Specification, the commutator is described as cousisting of
three contact pieces say Q, Q, Q an are of a circle larger than 90° fixed on an
insulating piece fixed to the tap or key so as to revolve as the tap or key is turned,
and the three plungers E, F, G, have pieces of metal connected to them so as to
come in contact in certain positions with the contact pieces on the key or tap, and
which pieces make connection with the contacts one + and the other connected
to the leads, so that in oue position the two metal pieces on the outer ends are in
connection with the lead and the two outer plungers, while the centre metal
piece is connected to + lead and centre plunger in which case the current enters at

page_text: -
the centre and leaves by the two ends, the next turn of the key disconnects the
centre plunger from the centre metal piece on key and causes one of the other two
metal pieces to cross over from lead to + lead, and the current then flows from
one outer plunger through the lamp back through the other outer plunger to other
outer metal piece then to contact of the lea ls. In practice however it is equally
efficacious if one plunger is connected always to lead N as shown and previously
described, as it leaves more room inside holder for the key and customary spring R
for keeping contacts true.
The contact plates of the lends affixed to the continuation of the socket base
have engaging pieces for connecting to the metal pieces two on the + side and one
on the side, so placed as to connect with the metal pieces on key or tap when in
positions as above.
A good method of fixing the metal pieces is to place a disc of insulating
material P, as for instance vulcanised fibre, with square hole in centre on to the
tap Pl, which is also of square section but which need not be of insulating material,
by a side pin T and which disc works between the two brushes F1, G', in connection
with the centre F and one outer plunger G and the engaging pieces on the disc to
make contact with the brushes M, E in connection with the respective leads.
The metal pieces are fixed on to the flat surface of the disc on opposite sides in
such a manner that the commencement of the second piece begins at about the
end of the first, and these pieces will be insulated by and revolve with the disc and
key P, P, respectively.
For moderating. a large number of lamps, the holders have only the three
plungers and a screw connection to each plunger to which holder is affixed a triple
wire, one wire to ench plunger, and all holders are connected in parallel to the
switch shown in Figure 19, which is also a disc of insulating material having two
pieces of metal on opposite sides but to avoid projection from the wall the disc is
placed flat while working between the engaging pieces connecting the + and leads
with the three leads (two + and one -) from switch to lamps, it being otherwise
in all respects similar to the commutator before described. Of course only two
leads are required from mains to switch and the cover and base of which are of
insulating material.
This switch will also be available as a double pole switch besides effecting the
commutation as described above. A spring R is placed underneath in usual
manner to prevent the key remaining in intermediate positions.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1. A lamp having a three way filament made or joined together to form one
piece, the three ends of which are connected to a collar base having one central
and two side contacts, whereby an alteration in the intensity of light obtained
from within the lamp is regulated from outside by causing the whole or only a
portion of the filament to glow, and. effecting said alteration in the intensity of
light emitted by sending current from one outside contact plate to the other, or
by sending current in at the centre, and out at the two side contacts, as set forth.
2. The necessary switching apparatus either for wall or tap for commutating
the direction of the current in a lamp having a three way filament consisting of a
dise of insulating material provided with metal connecting pieces on the opposite
sides of said disc, and so arranged in combination with contact pieces or brushes
connected to the leads and to the plungers as to cause the current to enter by
central contact, and leave by two outer contacts, or to enter at one outer contact
and leave by other outer contact and simultaneously disconnecting or short
circuiting the central contact of switch or breaking the circuit. altogether by a
series of movements of a tap or key in either direction, as described and
illustrated.
3. The improved apparatus for moderating electric incandescent lamps consisting

page_text: of two contact pieces Q, Q¹, secured to a disc P of insulating material fitted upon
and revolvable by a tap or key P¹ externally projecting from the socket H', also
a base H of insulating material having three spring plunger contacts E, F, G, and
brushes E, F, G₁, respectively electrically connected thereto and an extra
terminal or brush M for the common return wire, all being arranged within the
socket H and secured in position by the cap H2 for use in combination with a
lamp having a three way slament J, K, L, and a central and two outer contact
pieces A, C, D, respectively in the collar base B of said lamp, adapted to fit into
and be received by the socket H' for electrical connection with and control by the
switch mecbanism in the manner and for the purpose herein described.
1900
H. GARDNER,
Patent Agent, 166 Fleet Street, London,
Agent for the said Godfrey Bamberg.
H. GARDNER,
Patent Agent, 166 Fleet Street, London,
Agent for the said Godfrey Bamberg.