Improvements in Micro-telephones.
Year: 1893

page_text: Date of Application, 4th Dec., 1893
Complete Specification Left, 4th Sept., 1894-Accepted, 24th Nov., 1894
GEORGE LEE ANDERS, Electrician, and WALTHER KOTTGEN, Merchant, both
of 5 Great Tower Street E.C. do hereby declare the nature of this invention to be
as follows:-
The object of this invention consists in the simplification and improvement of
the various parts of the telephonic apparatus shewn in Patents No. 1637 dated
January 27th 1892 and No. 5712 dated March 23rd 1892.
This object is accomplished by making the parts, such as diaphragm, diaphragın
ring, bell contact, automatic switch, with the respective insulating rings, all of
which being of a circular concentric shape, capable of being placed the one above
the other, so that they may be all of them simultaneously clamped into position by
the face-plate which carries the receiver. In some instruments there may be
additional contacts for the local battery of an induction coil-these we propose
preferably to place in the cylindrical recess in the shape of two semicircles which
are clamped as above, the contacts being within the circle of these pieces.
Dated this Second day of December 1893.
GEORGE LEE ANDERS.
WALTHER KOTTGEN.
Improvements in Micro-telephones.
We, GEORGE LEE ANDERS and WALTHER KOTTGEN late of No. 5 Great
Tower Street, but now of No. 31 Queen Victoria Street, in the City of London,
Electrical Engineers, 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 :-
Our invention relates to improvements in the construction of telephones and
consists in making the automatic switch as well as the bell and other contacts in
the shape of rings or annuli or of portions of rings or half annuli insulated from
each other by respectively similarly shaped insulators. The object in making the
said organs of a telephone of either of the shapes described is that they may be
received and held in working position within a circular (or other shaped) recess in
front of and concentric with the recess which contains the microphone and its
diaphragm, the said organs being retained in position in the said circular recess by
means of the front plate on which the receiver is supported concentrically with the
microphone or of some other equivalent clamping ring or plate. The diaphragm is
also held in working position in the same way.
Referring to the accompanying drawings:
Figure 1 is a front elevation of our improved telephone (omitting the receiver).
Figure 2 is a vertical section taken on the line 2-2 of Figure 1.
Figure 3 is a front elevation after the removal of the front plate.
Figure 4 is a rear elevation.
Figure 5 is a plan of the bell contact.
Figure 6 is a plan of the automatic switch.

page_text: Figure 8 is a plan of the diaphragm.
Figures 9 and 10 are plans of the insulating rings.
Figure 11 is a front elevation of a modified form of telephone.
Figure 12 is a vertical section taken on the line 12-12 of Figure 11.
Figure 13 is a rear elevation.
Figure 14 is a side elevation of the automatic switch detached.
Figures 15 and 16 are plans of insulating rings.
a is the base of the instrument. The front plate above mentioned is shewn as
consisting of a ring & and a perforated plate made fast together concentrically
with each other. c is the semi-circular yoke adapted to hold the receiver and its
case when they are not in use. Both receiver and case are omitted from the
drawings because they are not affected by the present invention.
The front plate is held to the base a by screws 63, 63 which are passed through
the base a into the ring b.
On the back of the base the following terminals present themselves :-d, to the
line wire d'e, to the battery and ringing key: f, to the bell: f1 to the secondary:
g, h, to the receiver and i to the local battery. The microphone consists of a
carbon block; having a hemispherical cavity in its front face. This is filled with
carbonised fibre j'. The block itself is held to the base a by a tubular screw
device through which the cavity may he replenished. is a metal strip from the
microphone to the receiver terminal g. is the diaphragm. It stands within the
circular recess above mentioned, resting up against the face of a brass ring 11
which is held to the base a by screws and connected to the battery and key
terminal e by screws 12. m is a wad of cotton fast to a ring m'. The latter fits
over the edge of the cavity in the carbon block j and the former up to the
diaphragm for the purpose of preventing the carbonised fibre getting between
the edge of the cavity in the block j and the diaphragm . The above described
microphone and diaphragın, do not form a part of the present invention, being
substantially identical with those described in Letters Patent No. 12528,
July 7th 1892.
The diaphragm 1, the rim a' of the base a and the front plate b, b¹ form the
circular recess which receives, according to the present invention, the automatic
switch as well as the bell and other contacts.
n is the bell contact. It is a metal ring of the same diameter as the diaphragm !
from which it is insulated by a ring n¹ of the same diameter and area as itself.
The contact n is connected to the terminalf by means of a flexible thin metal
tab n² and screw n³. n is a metal finger projecting inwardly from the ring n in
the same plane and as far as the centre of it where its tip n is bent outwards to
the front so as to stand within reach of the automatic switch. The latter is a
second metal ring o of the same size as the ring (from which it is insulated by a
ring o of the same diameter and area as itself) and a finger described further on.
The ring o carries two tabs o², 03 on its outer. edge. With the former the arin p
of the ringing key is normally in contact, while the function of the latter is to fit
in a correspondingly shaped recess a² in the rim a¹ of the base so as to keep the
switch in working position. The said arm p is connected by the screws to the line
terminal do is the finger above mentioned and is the switch proper.
It is a
metal finger projecting from one side of the ring o to very nearly the other side.
It occupies a diametrical position so as to contact with either the nose n or with
the tips p of the contacts of the induction coil and the local battery described
further on. When a message is being sent through the telephone, the .finger o
stands in contact with the last mentioned contacts-compare Figures 2 and 7-
thereby projecting the nose piece o into the cavity of the yoke c, so that when the
receiver is hung up in the latter, it shall disconnect the contact of from the said two
contacts (p) and make it contact with the tip n' of the bell contact.
p', p² are two metal half rings of the same radius as the rings n and o. They
are sufficiently less than half rings to stand away, from each other when they are
made fast to an insulating ring p³-sec Figures 3 and 7. p*, p are two fingers

page_text: extending inwardly from the half rings pl, p² in the same plane and almost to the
centre, where their respectively bent back tips p stand in the path of the finger of.
The two half rings p³, p³ are connected with the terminals, f1 and i, by the
screws p, p passing through flexible thin metal tabs pop projecting from the
respective half rings. 7 is an insulating ring between the half rings p¹, p and
the front plate b, b or its equivalent clamping ring or plate.
11
It
The telephone contacts above described are adapted for use in a telephone
working inductively. The modification illustrated in Figures 11 to 16 is adapted,
on the other hand, for use in a telephone working with a direct current.
consists in the omission of the connections for the. local battery and the secondary,
reducing the connections on the back of the base a to five, and the contact rings to
one. The contact ring in question consists of two half rings r, r, held symmetrically
about their centre upon a ring of insulating material to which they are rivetted..
3 is a finger projecting towards the centre from the top of the ring and carrying
the nose piece oº. is a second finger projecting towards the centre from the
bottom of the ring and standing in the path of the backwardly bent tip of of the
said nosepiece. 75 is a thin flexible metal tab and a screw by which the half
ring is connected to the bell terminal f.
It is to be distinctly understood that we have described and illustrated our
improved contacts together with their insulations as annuli and half annuli because
the recess which receives them is circular, that being the shape of recess which is
the cheapest to make. It must however be explained that our invention does not
limit us to making the recess circular in form and the contacts and insulations as
annuli and half annuli. The recess may be square or of any other shape, in
which case the contacts and insulations will be of a corresponding shape to fit
therein.
We have already explained that it is the front plate b, b' or an equivalent
clamping ring or plate that holds the contacts the automatic switch and the
diaphragm in working position, and it does this by pressing upon them all
simultaneously and evenly at all points of their circumference so that none of them
are distorted as they might be if they were fixed to the base by means of holding
screws through their edges. The tabs and screws described in connection with the
contacts (such as p, p, p, p, 7, 78,) are only for making electric connection:
they have nothing to do with holding the contacts and diaphragm in working
position. For the latter, a clamping ring or plate is solely depended on. As it is
screwed up to the base a, it presses evenly upon all the contacts and insulations
alike, the flexibility of the tabs preventing the latter from pulling on the respective
contacts as the clamping ring or plate.
Further it is obvious that as the function of the front plate b, b', is, for the
purpose of the present invention, only to clamp the contacts and insulations within
the circular recess in front of the diaphragm, it may be replaced by any suitable
clamping ring or plate.
With reference to the receiver terminals g, h, although they are shewn as similar
to the others, they may be dispensed with altogether, and the ends of the wires g¹, h',
connected directly to the front plate 6, 61 and the microphone.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is :-
1. The combination of recess between the diaphragm and front plate with
contacts and insulations of the same shape as the recess whereby the said contacts
and insulations may be clamped in working position within the said recess and in
front of the diaphragm by a clamping ring or plate.
2. The combination of recess between the diaphragm and front plate, contacts
and insulations of the same shape as the recess and adapted to fit therein and a
clamping ring or plate clamping or adapted to clamp the said contacts and
insulations in working position within the said recess.

page_text: 3. The combination of contact half rings inwardly projecting fingers and
insulations.as described with reference to Figures 7 and 14.
Dated this 4th day of September 1894.
PHILLIPS & LEIGH,
No. 22, Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicants.