AN IMPROVED SWITCH FOR ELECTRIC CIRCUITS
Year: 1885

page_text: I, ERWIN ZELLER, of 2 Watt Place, Greenock, Renfrewshire, Civil Engineer, do
hereby declare the nature of my Invention for "AN IMPROVED SWITCH FOR
ELECTRIC CIRCUITS," to be as follows:-
My Invention consists in forming a spring switch for temporarily opening and
closing electric circuits, and more especially for use in connection with incandesence
lamps, by the use of a dished plate of metal suitably secured and provided with a
knob or handle, so that in one position of equilibrium it makes contact with the
terminal of the circuit, and in the other position of equilibrium it breaks the
circuit through it and such terminal. The knob is attached to the centre of
the dished plate which is secured at its edges, the convex surface or a projection
on it making contact with the terminal which may be a metal washer, a split tube,
a spring, or other usual connection. By withdrawing the knob the dished plate
assumes its other position of equilibrium in which the concave surface is presented
to the terminal but is out of contact with it. The spring plate and terminals are.
fitted in a suitable casing which may be hermetically closed.
W. R. M. THOMSON & Co.,
For the Applicant.

page_text: I ERWIN ZELLER now of 12 Finborough Road West Brompton in the County of
Middlesex 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:-
In forming a switch for opening and closing electric circuits more especially
for use in connection with incandescence lamps and for telegraphic and telephonic
circuits I use a metallic spring plate so curved and held that it will remain at rest
and in equilibrium in either one or other of two positions but not in any inter-
mediate position. When in one position I cause it to make contact between the
terminals of the circuit and in the other position to break the circuit through these
terminals I also provide it with a knob or handle by which it can be pulled or
pushed to shift it from one position to the other.
The plate may be circular and secured to rigid supports all around its circum-
ference and dished in cross section in whichever direction the section may be
taken or it may be a rectangular plate supported at two opposite ends and be
dished in cross section in one direction only viz; those taken across from one
support to the other, It is also evident that such a plate may be slit or cut away
in parts until it becomes a series of curved parallel wires or a single curved wire.
The plate also might be dished or curved somewhat into a spoon shape and be held
at one end only the contact making instrument being carried at its other end.
The drawings hereunto annexed show examples of electrical switches formed as
above described.
Figure 1 is a cross section of one form of the switch. A is the outer casing.
formed of wood or other non-conducting material. B the spring plate which may
be of brass, copper, steel or other suitable metal. C is a knob or handle secured to
the centre of the spring plate. D is the metallic head of a screw by which the
knob C is secured to the spring plate B. E is a metallic ring fixed by screws to
the bottom of a recess in the casing on the inner side of the plate B-F is an
elastic washer interposed between the ring E and the bottom of the recess. The
end of one of the wires of the circuit is as shown led in through the casing and
coupled to the metallic ring E so as to make contact therewith. The end of the
other wire is as shown put into metallic connection with the spring plate B.
When the spring plate B is in the position shown in the drawing the head of
the screw D is away from the metallic ring E and the circuit is broken but when
the knob C is pressed inwards the head of the screw comes into and remains in
contact with the ring and the circuit is completed between the terminals.
The spring plate may be in the form of a circular disc as shown in face view at
Figure 2 or as a rectangular strip as shown in face view at Figure 3-or as such a
strip divided into two or more parallel strips as shewn in face view at Figure 4 or
as a single narrow strip or wire as shewn in face view at Figure 5.

page_text: When the spring plate is formed as a circular disc it may be held around its
circumference within the casing A either by holding its edge between the lid and
body of the casing in which case the lid may be held down by screws or by being
made to screw on to the body of the casing. Or the edge of the disc might be
held down to the body of the casing by screws the stems of which are passed
through notches formed in its edge at intervals around its circumference or other
suitable means might be adopted for holding down the edge of the disc.
A face view of the switch with the spring plate so formed of a circular disc is
shown at Figure 6, in this figure the lid A¹ of the casing and part of the spring
plate with its knob or handle Ō are removed.
;
Figure 7 is a similar view of the switch where the spring plate is in the form of
a rectangular plate such as shown at Figure 3.
When the spring plate B is divided into a number of parallel strips as shewn at
Figure 4 these parallel strips may as shewn be all united together at the centre
by securing them all to a strip of metal placed across them. If a single narrow
strip or wire B such as shown at Figure 5 be used guides may be provided to
ensure that the knob or handle C secured to its centre shall only be able to move
in a direction directly towards or from the centre of the metallic contact piece E.
In Figure 5 this is shown to be effected by a spring blade C secured at one
end to the body of the casing and at the other end to the wire where the knob is
secured to it.
A face view of the switch complete is shewn at Figure 8.
Preferably I make the centre of the plate to bulge normally to one side or the
other by hammering stamping or bending but if a single narrow strip is used such
as shewn at Figure 5 or a series of narrow strips as shewn at Figure 4 straight
strips of metal might be used and the strips be made to assume the required dished
form by causing one end of each strip to be pressed endwise towards the other end
by a strong spring.
This may be effected in the way shown at Figure 5. In this figure the wire is
shown to have a metallic head secured to one of its ends and this metallic head is
made to rest against a small washer of vulcanized india rubber L contained in a
recess in the body of the casing.
It is not essential that the circuit should be carried through the spring plate B
and contact made by the head of the screw D being brought against the metallic
washer E. Any suitable means of completing a circuit when the spring plate is
pressed inwards may be adopted. For example it might be completed in the way
shewn in the cross section of a switch at Figure 9.
In this construction one of the wires of the circuit is secured to one terminal ·
bar H and the other wire of the circuit to another terminal bar I. The ends of the
bars are as shown made to overlap one another and a hole is bored through each
into which a metallic pin J can pass. When the knob C is pressed inwards the
pin J fits into the holes in both the terminals and the circuit is completed-but
when the knob is drawn outwards the pin is withdrawn from the hole in the
terminal I and the circuit is broken.
As before stated the spring plate instead of being held at two or more points
might be held at one point only.
A cross section of an electric switch formed in this way is shewn at Figure 10.
A face view of the switch with the cover removed is shown at Figure 11. In the
construction shown the spring plate is dished somewhat into the form of a
spoon and one of the wires of the circuit is coupled to the fixed end of the dished
plate and the other wire to a metallic plate K-When the knob or handle C is
pressed inwards the head of the metallic screw is brought into contact with the
metallic plate K as shewn in Figure 10 and the circuit is completed but when the
handle is drawn outwards the head of the screw is held away from the plate K
and the circuit is broken.

page_text: ! 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
1. An electric switch in which a curved metallic spring plate or its equivalent
which is capable of assuming and remaining at rest in either one or other of two
positions but which will not remain at rest in any intermediate position is
employed to hold one contact piece away from or up to a second contact piece so as
either to break or complete a circuit substantially as described.
2. The construction of electrical switches substantially as hereinbefore described
and illustrated in the drawings annexed.