IMPROVEMENTS IN TELEPHONE RECEIVERS
Year: 1882

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of “IMPROVEMENTS IN
TELEPHONE RECEIVERS." A communication from abroad by George Milton
Hopkins, of Brooklyn, in the County of Kings and State of New York,
United States of America.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 11th February 1882.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
Patent Agent. IMPROVEMENTS IN TELEPHONE RECEIVERS. [A communication
from abroad by George Milton Hopkins, of Brooklyn, in the County of Kings and
State of New York, United States of America.]
The object of this Invention is to obtain increased efficiency compactness and
lightness in receiving telephones.
According to one modification of receiving telephone a series of right angled
permanent magnets are arranged radially with their poles of like sign converging
to and touching the soft iron core of a central magnet or helix and their other
poles in contact with the underside of the iron diaphragm near the circumference
thereof.
The soft iron magnet core is in the centre of the case and in close proximity to
but not touching the diaphragmn and at its other end it has a broad thin flange
against which the poles of the magnets are pressed by an elastic rubber ring
confined between them and the back of the case to which the core is attached by
a screw.
Perfect contact of the other poles of the magnets with the diaphragm is ensured
by the pressure of an elastic rubber ring placed between the magnets and the back
of the case near the anglo of the former. The soft iron core is surrounded by a
fine wire helix whose terminals are connected to binding posts.
With this arrangement of permanent magnets, soft iron core and iron diaphragm
the core and diaphragm are magnetic by induction and there is a consequent point

page_text: in the centre of each the two points being of opposite names, there is a constant
attraction between the diaphragm and magnet core which is varied by the passage
of a primary or secondary current over the wire of the helix.
According to another modification a non-metallic diaphragm is vibrated by a
polarized armature. The diaphragm case is attached to one limb of a permanent
U magnet and the diaphragm is made of non-metallic material preferably of the
kind of paper known as Bristol board which is soaked in paraffin.-To the other
limb of the permanent magnet is attached a soft iron core which projects towards
the other limb and is surrounded by a helix of fine wire whose terminals are
connected to the line and ground wires as usual. A cylindrical armature of soft
iron is attached to the centre of the diaphragm and extends through the back of
the case and through an opening in the adjacent limb of the permanent magnet
into close proximity to the face of the core.-Ono end of a spring fixed to the
case is interposed between the diaphragm and armature and its pressure against
the diaphragm and in opposition to the attractive force of the magnet is capable of
adjustment.
The armature is polarized by proximity to the fixed pole of the magnet and
electrical impulses sent over the line with which the receiver is connected and
through the helix vary the attractive force of the magnet and produce movements
or vibrations in the diaphragm.
In another modification two curved permanent magnets have like poles over
lapping and attached to a central core are placed within the case a short distance
below the diaphragm with the core facing the diaphragm which is non metallic.
Between the outer ends of the permanent magnets and the internal flange of the
case to which they are attached are clamped soft iron springs one of which extends
over and slightly beyond the end of the core, very near but not touching it. The
other spring extends over the end of the first spring but does not touch it. The
first spring is connected by a threaded stud with the centre of the diaphragm by a
nut at each side of the diaphragm.
A helix of fine magnet wire is placed upon the core and connected with the
binding posts to which the line and ground wires are respectively attachod.
With this construction there are consequent points one in the core the other in
the springs. Whenever an electrical impulse is sent over the lino wire the
attractive force of the magnet is varied and the spring and the diaphragmn attached
thereto are moved accordingly.
In another modification the diaphragm armature and electro magnet are so
arranged relatively with respect to each other that the armature will be vibrated
by the electro-magnet in a plane at right angles to the plane of the diaphragm.
A curved permanent magnet extends round the inner circumference of the case
to which it is fixed.-Its ends are bent slightly inwards and are provided with soft
iron cores and fine wire helixes connected in the usual way of connecting the coils
of an electro magnet and with the line and ground in the usual way. The cores
face a cylindrical soft iron armature supported by a stud attached to the centre of
the diaphragm. Any electrical impulse sent over the telephone line and through
the helixes affect the attractive power of the magnet and cause a movement of the
armature in a plane at right angles to the plane of the diaphragm which is
communicated to the armature through the stud.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Great Seal Patent Office on the
11th August 1882.
ALEXANDER MELVILLE CLARK of 53 Chancery Lane in the County of Middlesex
Patent Agent.
"IMPROVEMENTS IN TELEPHONE RECEIVERS." A communication
from abroad by George Milton Hopkins of Brooklyn in the County of Kings and
State of New York, United States of America.
The object of this Invention is to secure in receiving telephones compactness
lightness, and increased efficiency.
Figure 1 in the Drawings is a diametrical section of the improved receiver
shewing the arrangement of angled magnets, iron core, and helix. Figure 2 is a
plan view of the telephone receiver shewn in Figure 1, the diaphragm being
removed to shew internal parts. Figure 3 is a side elevation partly in section of a
modified form of receiver in which a non-metallic diaphragm is vibrated by a
polarized armature. Figure 4 is a diametrical section of a modification of Figure 3
and Figures 5 and 6 are respectively horizontal and transverse sections of a form
of receiver in which the telephone effects are secured by the vibration of an
armature in a plane at right angles with the plane of the diaphragm.
Referring to Figures 1 and 2 of the Drawing the cylindrical case A, is closed at
one side and is provided on the other side with an annular cap B, which screws on
the case and clamps the iron diaphragm C at the edge tightly between it and the
top of the case. In the centre of the case, and in close proximity to the diaphragm C,
though not touching it, there is a soft iron magnet core D, having a broad thin
flange E, formed on or attached to its inner end. This magnet core D is held in its
place by a screw F passing loosely through the back of the receiver case A and into
the end of the soft iron magnet core. Between the magnet core D, and the back
of the case A, and surrounding the screw F there is an elastic rubber ring G of
smaller diameter than the flange E, of the core D.
Between the elastic rubber ring G and the flange E of the core D, are placed the
ends of several right angled permanent magnets H with their opposite ends in con-
tact with the iron diaphragm C; poles of like name being placed in contact with the
diaphragm. Perfect contact of the ends of the magnets with the diaphragm, is
secured by the pressure of an elastic rubber ring I placed between the magnets H
and the back of the case A as near as possible to the angle of the magnets.
The soft iron magnet core D is surrounded by a fine wire helix L whose
terminals are connected with the binding posts K screwed into the back of the
case A.
With this arrangement of permanent magnets, soft iron magnet core, and iron
diaphragm, the magnet core and iron diaphragm are magnetic by induction and
there is a consequent point in the centre of each; the two points being of opposite
names there is a constant attraction between the diaphragm and magnet core
which is varied by the passage of a primary or secondary current over the wire of
the helix L.
Referring to Figure 3 A¹ is a diaphragm case attached to one of the arms of the
permanent magnet B¹ and supporting the diaphragm C', which is clamped
between the two parts a, b, of the case A¹. This diaphragm C² is made of non-
metallic material preferably of the kind of paper known as Bristol board which is
soaked in paraffine. To the outer arm of the permanent U magnet, near the end,
is secured a soft iron magnet core D' which projects toward the opposite arm of
the magnet and is surrounded by a helix E¹ of fine insulated copper wire.. The
terminals of the helix E' are connected with binding posts F1 which receive the

page_text: line and ground wires in the usual way. A cylindrical armature G₁ of soft iron is
attached to the centre of the diaphragm C, and extends through the back of the
case A¹ and through an opening in the fixed arm of the U magnet B¹ into close
proximity to the face of the core D¹.
One end of a spring c, is interposed between the diaphragm C¹, and armature G¹.
The other end of the spring is secured to the inner side of the back of the case A'.
The pressure of the spring c, against the diaphragm and in opposition to the
attraction force of the magnet, is varied by the adjusting screw & passing through
the back of the case A¹ and bearing against the spring.
The armature G¹ is polarized by proximity to the fixed pole of the magnet B'.
Electrical impulses sent over the line with which the receiver is connected, and
through the helix E' vary the attractive force of the magnet and produce move-
ments or vibrations in the diaphragm.
In the receiver shewn in Figure 4 the diaphragm A³ is supported in the case B³,
in the usual way and two curved permanent magnets O³, D³, with like poles
attached to a magnet core E³, are placed in the case B, a short distance below the
diaphragm A, with the core E*, facing the diaphragm. Between the outer ends of
the magnets C, D, and the internal flange of the case B³, to which they are
attached, are clamped the soft iron springs C³, D³, one of which, C³, extends over
and slightly beyond the core E2, very near the core but not touching it. The
other spring D³, extends over the end of the spring Cs, but does not touch it. The
spring C, is connected by a threaded stud e with the diaphragm A², by two nuts
one on each side of the diaphragm.
A helix F3, of fine magnet wire is placed upon the core E³, and its terminals are
connected with the binding posts G³. One of the binding posts is connected with
the line wire the other with the ground.
With this construction there are consequent points one in the core E², the other
in the springs C³, D³. Whenever an electrical impulse is sent over the line wire
the attractive force of the magnet is varied and the spring C³, and diaphragm Aª
are moved accordingly.
A
Referring to Figures 5 and 6 the diaphragm A³ is mounted in the case B³ in the
usual manner, being clamped by the annular cap E³ upon the face of the case.
curved permanent magnet F³, with soft iron cores f, and fine wire helices G³ is
secured to the inner surface of the case by a screw g. The soft iron cores of face a
cylindrical soft iron armature H³, supported by a standard I³, attached to the centre
of the diaphragm A³. The helices G³ are connected together by one terminal of
each in the same manner as the spools of an electro magnet. The other terminals
are connected with the binding posts K³. The binding posts K³, are connected
with the line and with the ground in the usual way. Any electrical impulse sent
over the telephone line and through the helices G³ affect the attractive power of
the magnet, causing a movement of the armature H³ which is communicated to the
diaphragm A³, through the standards I³.
Having described the nature of the Invention and the manner of performing the
same I declare that what I claim as the Invention to be protected by the herein
before in part recited Letters Patent is :-
1st. In a receiving telephone, a series of bent permanent magnets arranged
radially, touching a soft iron magnet core near the point of convergence, and
contacting at their outer ends with an iron diaphragm, as herein specified.
2nd. In a receiving telephone the combination of the angled permanent
magnets H, soft iron core D, helix L, and iron diaphragm C, as specified.
3rd. In a receiving telephone, the elastic rubber rings G and I, and magnets E,
in combination, substantially as herein specified.
4th. In a receiving telephone, the combination of the non metallic diaphragm C¹,
permanent magnet B¹, polarized armature G', core D', and helix E¹, as herein
specified.
5th. In a receiving telephone, the combination of the adjustable spring c, and
armature C¹ as specified.

page_text: 6th. In a receiving telephone, the permanent magnets O³, D³, with like poles
overlapping on the core E³, helix F2, springs C³, D³, and non metallic diaphragm A²,
in combination substantially as specified.
7th. In a receiving telephone, the curved permanent magnet F provided with
pole extensions f, and helices Gs, the armature H³, and diaphragm A³, in combination,
as herein specified.
8th. In a receiving telephone, a diaphragm, an armature, and an electro magnet,
arranged relatively with respect to each other so that the armature will be vibrated,
by the electro magnet in a plane at right angles to the plane of the diaphragm,
substantially as specified.
In witness whereof I the said Alexander Melville Clark have hereunto set my
hand and seal this Tenth day of August in the year of our Lord One
thousand eight hundred and eighty two.
A. M. CLARK. (L.S.)