Improvements in or relating to Incandescent Electric Lamps.
Year: 1894

page_text: PROVISIONAL SPECIFICATION..
Improvements in or relating to Incandescent Electric Lamps.
1, WALTER THOMAS KERR of 67 Mere Road, Leicester, Electrical Engineer,
do hereby declare the nature of this invention to be as follows:-
The object of the present invention is to effect improvements in incandescent
electric lamps by means of which the illuminating power of the lamp. may be
decreased or lowered when for any reason it is desired to turn down the light
without extinguishing it.
For this purpose I employ in connection with an incandescent electric lamp two
filaments, the light of one of which is capable of being extinguished while the
current supplied to the other filament remains undisturbed.
Where the two filaments are of equal candle power the consumption of current
is reduced to one-half by. turning out the light of one filament, but in the event of
two filaments of unequal candle. power being employed the greater of the two may
be extinguished while only a very small power filament may have the current
supplied to it.
For this purpose I may connect to the holder, a tap or switch moving in.contact
with an inclined plane, cum surface or its equivalent so that when the said tap is
turned or slightly rotated it moves a contact block or piece into contact with one
of the leading in wires or contact wires connected thereto thus completing the
circuit.and causing one filement to impart light.
A further movement or partial rotation of the tap or switch will push, the contact
block or piece into contact with a second leading in wire or its connection:aud thus
complete the circuit of the second filament.
Upon the tap or switch being turbed in the opposite direction the current
becomes disconnected from one of the filaments--preferably. the larger candle power
where two unequal candle power filaments are employed-and the current is then
only supplied to the smaller candle power filament which alone gives light.
Dated this 29th day of September 1894.
improvements in or relating to incandesc
1, WALTER THOMAS KERR of 67 Mere Road, Leicester, 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 has for its object to provide an incandescent electric lamp with
more than one filament of equal or different illuminating power any one or more of
which may be used according to the illuminating power required.
The invention will be best understood by reference to the accompanying
drawings, in which
Figure 1 is a view partly in elevation and partly in vertical (section of a lamp

page_text: and fittings constructed according to this invention, the leads and branch connections
being shown diagrammatically and
Figures 2 and 3 are diagrams illustrating the operation of a convenient form of
switch (also shown in Figure 1) for controlling the lamp.
Like letters indicate like parts throughout the drawings.
A is the lamp bulb within which are provided two filaments BC of, either equal
or different illuminating power; for enabling the full scope of adjustability of the
illuminating power of the lamp to be properly appreciated it is herein assumed that
the filaments B Care of different illuminating power, for example B of say eight
and C of 'say sixteen candle power. These filaments are sealed into bulb A in the
ordinary manner and their terminals are connected with the line wires D E in the
following manner viz. the lamp-terminals B and C are both connected together
and, by the branch lend D' directly, that is to say without necessarily the inter-
vention of a switch or key to the line wire D and the lanip terminals B2 and C
each through branch leads B B and C C respectively and a key or switch F
to the line wire E. In actual practice the two branch leads B C may be replaced
by a single one which would be connected to the two contact blocks B.C
hereinaiter described, as will be well understood.
The switch, which, as a whole is herein referred to by the letter (which letter
is also berein used for referring to the switch spindle as an individual part) as
shown in Figure 1 comprises a plate F of non-conducting material suitably.
supported in the mount or lamp holder G and having secured upon it the previously
mentioned contact blocks B and C to which the leads B and C are respectively
permanently connected, and two spring contacts B and C to which the leads B
and Care respectively permanently connected. Beneath the spring contacts Be C
is arranged the before mentioned spindle F suitably pivotted in the lamp holder Gi
and provided with a knob or handle F at the outside of the mount to enable it to
be readily turned on its axis. On the spindle F are provided two cams B'C'
located respectively adjacent to the spring contacts Be C. For convenience of
more clearly illustrating the different positions of tlie cams B'C' under different
conditions of operation of the lamp they are shown detached from one another in
the diagrams Figures 2 and 3, but it is to lie noted that these are connected
together as in Figure 1 and cannot be operated independently of each other. The
cain B is formed with two operative projections B B and a gap B' which
separates B and B°; the cam C is in the form of a continuous segment its edge C
corresponding as regards its circumferential position about the axis of the spindle F
with the edge B" of the cam B².
:
When the lamp is switched out of circuit the key F occupies such a position that
neither of the cams,B7 C7.bears against its contact spring Be or C, this position is
not indicated in the drawings. When it is desired to obtain say an eight-candle-
power light the key F is turned from the last named position partly round in the
direction indicated by the arrows so that the projection B of the cam Bis caused
to bear against the spring contact B and press it into contact with the block B° as
shown in Figure 1, the cam C7 not yet having reached the spring contact C. The
circuit will then be completed through the filament B the course of the current
being from the source of electrical energy through say the line wire D and
successively through the lead D', lamp-terminal B' filament 1, lamp terminal B²,
branch lead B, spring contact B, contact block B, branch lead B, line wire E
and thence back to the electrical source all as indicated by the arrows a in
Figure 1.
When it is desired to obtain say a sixteen candle power light the key is turned
further round in the direction indicated by the arrows f until the gap 1° of cam 137
is presented to the spring contact Be (which immediately flies away from the
block 13) and simultaneously therewith the cam C7 bears against the spring-
contact which is consequently pressed into contact with C as shown in Figure 2,
the circuit then being broken through the filament A and completed through the
tilament B. The course of the current is then from the source of electricity

page_text: through say the line-wire D, branch. lead D,,lamp terminal C, filament C, lamp.
terminal C, branch lead C³, spring contact C, contact, block C³, branch load, C,
line wire E and thence back to the electrical source, all as indicated by the
arrows a in Figure 2.
When it is desired to obtain say a twenty-four-candle-power light the key Fis.
turned still further in the 'direction indicated by the arrows so that while the
cam C' still bears against the spring contact Co the projection. Bº of cam B7 is
also brought to bear against the spring contact B the result of which-as shown by
the arrows a in Figure 3, is, that the current flowing through the lead D'is divided.
at B C passing partly in the direction indicated by the arrows a in Figure'l and
partly in that indicated by the arrows a in Figure 2 both the filaments BC being
thereby brought to and simultaneously maintained in a state of incandescence. ...
To cut the lamp entirely out of circuit the key F may be turned still further in
the direction indicated by the arrows so as to remove both of the cams B C out
of contact with the respective spring contacts B C; if desired however, the back:
end of the cam C' may be in advance of that of the cam B7 so that instead of the
filaments B and C being cut out of circuit simultaneously and the light thereby
suddenly extinguished, C will be cut out before B, the light being thereby reduced
before final extinction.
The current has been herein described as flowing in a particular direction; this
has been resorted to merely as a means of facilitating the understanding of the
invention for the current might equally well be supposed to flow in the opposite.
direction.
..
In the drawings I have diagrammatically represented the branch leads B³ C³
and D as connected directly with the lamp terminals B² and C² and `B'‍C' but in
actual practice, as the lamp would be detachably secured in the mount or holder G
it (the lamp) would have three terminal plates, to two of which the terminals BC:
would be respectively connected and to the third the two terminals 'B' C' would
be connected. These three terminal plates would be arranged to make contact
with three spring-controlled plungers or other contact devices, such as are ordinarily
provided for the purpose in the. holder G, the three branch leads B³'C³ D' being
connected each with one of these devices as will be readily understood by electricians.
and others skilled in the art.
Although I have herein described my improved lamp as provided with twɔ
filaments I wish it understood that I may employ more than that number in the
samo lamp the only essential requirements being that their terminals shall be so.
connected together and to the line wires D and E and a suitable switch provided
that the circuit may be completed through either all or any one or more of the
filaments. The terminal plates of each lamp constructed according to this invention
will preferably exceed by one the number of filaments to which they are connected,
one end of each filament being connected to its own particular terminal plate, and
the other end to a terminal plate common to all of the filaments, thus in a lamp
with two filaments as shown in the drawings, there would be three terminal plates,.
in a lamp with three filaments there would be four terminal plates and so on.
Provided however that the key or switch and contact devices be arranged so that
the circuit may be completed through all or any one or more of the filaments as
before described there may be as many as twice the number of terminal plates as.
filaments that is to say each end of each filament may have its own terminal plate,
the lamp terminals or the terminal plates must however, in a lamp in which each
filament is capable of independent operation, always be in excess of the number of
filaments and not less than or equal to it as is the case with lamps as ordinarily
constructed with multiple filaments wherein all the filaments must be simultaneously
in or out of circuit.
If desired, in a lamp provided with say three filaments any two of them may be
permanently connected together so that there would virtually be .ns regards this
invention only two separate filaments and in a lamp having say four or more
filaments any number thereof short of that of the actual number of the filaments

page_text: "may be permanently connected together to the exclusion of one or more of the
others these connected filaments constituting what are as regards this invention
"considered each such combination as a single filament, the permanently-connected
filaments all being included in or cut out of the circuit simultaneously.
i In a lamp provided according to this invention with three 'filaments 'which are
"each" capable of being illuminated independently of and variously combined' with
the others and wherein the filaments are all of different illuminating power 'there
may be lights of as many as seven different powers obtained by using "them
separately and in all their various possible combinations.
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 :-
i
1. The combination in an incandescent electric lamp of more than one filament.
so arranged or connected that they can be independently turned on or off.
2. An incandescent electric lamp provided with a plurality of filaments with
their terminals so arranged that the filaments may each be independently introduced
into or cut out of circuit.
3. The combination in an incandescent electric lamp of a plurality of filaments
whose terminals are combined to form three or more independent terminals so that
the electric current may be passed' through any one of the filaments or simultaneously
through any two or more of them.
1
4. An incandescent electric lamp provided with a plurality of filaments of which
any two or more are connected' in series and have terminals admitting of the
current passing through them independently of the other filament or filainents
whose terminals are so arranged that any one or more of these filaments may be
introduced into or cut out from the electric circuit independently of the other or
others..
5. The combination with an incandescent electric lamp having a plurality of
filaments each provided with 'terminals admitting of its being introduced into or
cut out of the electrical circuit independently of the other filament or filaments of
a key or switch for effecting the introduction or cutting out of any one or more of
the filaments from the circuit.
6. The combination with an incandescent electric lamp having a plurality
of filaments arranged so that they may independently or in any combination be
introduced into or cut out from the electric circuit of a switch comprising a spindle
such as Fa plurality of cams thereon and a plurality of contact devices such
as 'Bª Bª.and Cª˚C substantially as described and illustrated in the accompanying
drawings.
تيمم
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