Improvements in Electric Telephones.
Year: 1892

page_text: COMPLETE SPECIFICATION.
[Communicated from abroad by ELWOOD ARISTIDES GRISSINGER, Electrical
Engineer, and THEODORE GRISSINGER, Manufacturer's Agent, both of
82, South Market Street, Mechanicsburg, in the County of Cumberland and
State of Pennsylvania, United States of America.]
Improvements in Electric Telephones.
I, HENRY HARRIS LAKE, of the firm of Haseltine Lake & Co., Patent Agents,
45 Southampton Buildings, 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 :-
This invention relates to improvements in electrical telephones, and the purpose
thereof is to provide a receiver wherein the vibrations of the metallic disc, or
diaphragm produced by the variations in intensity of the magnetizations of the
permanent magnet, shall produce sound-waves which traverse the receiver in
parallelism with its axis and are constantly amplified, as they approach the ear,
thereby causing an increase in intensity and a marked improvement in the distinct-
ness of the reproduced vibrations. The invention also has for its purpose the
provision of certain novel features in the construction of the permanent magnet,
whereby molecular vibration is largely increased and concentrated, together with
other improvements in construction and arrangement of parts.
Another object of the said invention is to provide a transmitter which shall be
extremely sensitive and susceptible to phonetic vibrations of very low intensity.
A further object is to provide a transmitter having a diaphragm of novel con-
struction, connected electrically with the line-wire, the construction of said
diaphragm being such that it obtains a larger body, or mass, under pressure and
an increased field of electrical saturation in the resistance-offering conductor.
A still further object is to employ either a carbon diaphragm, or, preferably, one
formed of a perforated or foraminous substance, plated or otherwise coated with
carbon, whereby it is rendered more sensitive than a diaphragm of the ordinary
construction.
To enable others skilled in the art to make, construct and use said invention, the
same will be described in detail with reference to the accompanying drawings in
which,
Figure 1 is a central longitudinal section of a telephonic receiver constructe
substantially in accordance with said invention.
Figure 2 is a similar section, showing a slight change in the construction of the
exterior shell, or handle.
Figure 3 is a detail view of the diaphragm.
Figure 4 is a similar view showing a further modification of the diaphragm.
Figure 5 is a vertical section taken from the front to rear of a transmitter for a
contact telephone, embodying my invention.
Figure 6 is a similar section, showing a substitute construction of the pressure-
regulating devices.
Figure 7 is a rear elevation of the pivoted pressure-lever, shown in the side-
elevation in Figure 6.
Figure 8 is rear elevation of the diaphragm and its mounting, showing, also,
one manner of making the line-connection, and
Figure 9 is a sectional detail on an enlarged scale of the diaphragm.
1 denotes the outer shell, or handle of the receiver, which is usually of
cylindrical form, and constructed from any suitable material, such for example, as
hard rubber. At one end of this shell is formed a collar 2, having a male thread,
upon which is screwed a cap 3, having an interior concave face 4, concentric with

page_text: the axis of the shell 1. Between this cap and the end of said shell is arranged the
metallic diaphragm 5, its margin being clamped between the two contacting
surfaces formed by the face of the collar 2 and a narrow shoulder 6, lying between
the concave face of the cap and its threaded flange 7.
Within the shell, or handle, and nearly coincident with the length thereof, is
arranged a permanent magnet 8, composed of a substantially cone-shaped, or
conoidal shell of steel, permanently magnetized, having its axis substantially
coinciding with that of the exterior shell 1. The enlarged end of the metallic
shell lies at the open end 9 of the receiver, which is provided with an annular
piece 10, forming an ear-piece and providing an internal collar for the end of the
magnet. At a little distance from its other and smaller end, the metallic shell, or
magnet, assumes an exterior, cylindrical form, while retaining the conical shape of
its interior face. By this construction, the end 12 of the magnet, adjacent to the
diaphragm is gradually thickened and mounted thereon is the spool 13, containing
the fine wire of the induction coil, the terminals of which pass to binding posts 14,
beyond which they are insulated, united, and connected with the line and with
earth in the usual manner.
The flanges of the spool 13 are of such diameter as to fit the interior of the
shell, or handle, and provide a support for the end 12 of the permanent magnet.
The construction described is capable of modifications by making the exterior
shell, or handle, conform more or less closely to the form of the permanent magnet,
as shown in Figure 2. In this modification the induction coil and the end 12 of
the magnet on which it is mounted, are enclosed by a spherical segment 15, formed,
or mounted, on the smaller end of the cone-shaped handle. As the end of the
permanent magnet is thus deprived of its support by the flanges of the spool of
the induction coil, its enlarged end is attached to a movable ear-piece 16, which is
provided with an interiorly threaded flange 17, screwing upon a collar 18 on the
end of the handle. The end of the magnet is provided with a collar 19, resting
against the inner face of the ear-piece to which it is fastened by screws 20. The
magnet is adjusted toward and from the diaphragm by the screw adjustment of the
ear-piece 16 upon the handle. In other respects the construction is not materially
different from that already described. A hook 21 is usually attached to the cap 3,
whereby the receiver is connected to the cut-out on the telephone.
It will be seen that by means of said invention increased efficiency is given
to the receiver, as all the undulations set up by the vibrations reproduced by
the diaphragm are rendered effective by reflection from the concave inner face of the
cap, and by a concentration, or focussing, of the same upon the diaphragm. The
conical inner surface of the permanent magnet, also, forms a reflecting and
amplifying surface by which the undulations are caused to travel in parallelism
with the axis of the shell. Moreover, if the theory of molecular vibrations is
accepted, it would seem that this form imparts a greatly increased surface and, in
a measure, directs, or concentrates, the lines of molecular movement toward the
external auditory meatus.
By the construction of the permanent magnet shown, a largely increased surface
is secured for the magnetization of the induction-coil, as well as a greater mass for
saturation, and a simple and accurate adjustment is provided for the permanent
magnet, relatively to the diaphragm. As a result of these features a greater
volume, or reproduction of sound is obtained, which is clear and well defined, while
the phases of articulate speech are reproduced with increased accuracy.
It should be noted that in some cases a diaphragm 5 is used, provided with a
group of perforations, or openings 22, as shown in Figure 3, whereby the
vibrations reflected from the concave face 4 of the cap may have free passage.
The ear-piece 10, in Figure 1, is provided with small bolts, or screws 20,
engaging an internal collar 19 on the large end of the permanent magnet, whereby
the latter is rigidly connected to the ear-piece. By screwing the latter further on
or off, the permanent magnet may be adjusted relatively to the diaphragm 5,
which, in this figure and in Figure 2, is shown as solid, or imperforate. In order

page_text: to lock the parts after the adjustment is effected, a set screw 23 is tapped through
the external collar 18, its end abutting against the ear-piece and holding it fast.
Any form of perforation in the diaphragm, and any number of such perforations
may be used. In Figure 4, is shown a modified form of these openings.
Referring to Figures 5 to 8, both inclusive, the reference numeral 1 indicates
the case, or transmitter-box, in one vertical wall of which is formed the usual
sound opening 2.
In the rear face of this wall is formed a recess 3, in which is
placed the diaphragm 4, which is constructed preferably as follows:-
A sheet, film, or disc of any suitable material, metallic, or non-metallic substance,
is either perforated, or otherwise so formed that it shall have numerous openings,
at substantially equal intervals, or nearly so. A good material for this purpose
is wire gauze, or wire-netting of suitable fineness, though a perforated metal film
gives good results, and any non-metallic material capable of receiving a carbon
coating or plating, and giving the proper responsive vibrations, may be used, if
preferred.
The disc, sheet, or film, is coated, or plated, with carbon 6, in such manner that
the latter fills the interstices of the perforated or foraminous sheet, or disc, and
provides a diaphragm which is practically a homogeneous imperforate mass of
carbon, but possessing also, the resilience of the metal, or other foundation
forming part thereof. The diaphragm thus formed is placed, in the recess 3,
behind the sound-opening 2, which is concentric with said recess. The marginal
portion of the diaphragm is enclosed in a cushion 7, formed of any suitable substance
and in any way preferred, this being a feature too well understood to require
specific description. The diaphragm is retained in place by clasps 8, usually of an
elastic material, their ends being provided with cushions 9, which rest against the
rear face of the diaphragm in close proximity to the cushion 7. The line connec-
tion with the diaphragm is made by means of an elastic contact plate 10 mounted
by one end upon the transmitter-box, and having its free end resting upon the
diaphragm near the marginal cushion, between two of the clamps 8. Upon the
rear face of the diaphragm, at its centre, or in axial line of the sound opening 2,
is formed, or mounted, a carbon button 12.
Hanging from the top of the casing, or transmitter-box is a bracket 13, to which
is secured a spring strip, or elastic plate 4, which extends downward and is curved
toward the centre of the diaphragm 4, its extremity being provided with a
secondary electrode 15, which may be either carbon, or metal, pressed by the
spring 14 against the carbon button 12. From the spring strip 14, below the
supporting bracket 13, diverges an auxiliary, or secondary, pressure-adjusting
strip 16 which is extended downward far enough to permit the engagement with
its end of a set screw 17, tapped through a post 18 rising from the floor of the box.
By manipulating this set screw the elastic pressure of the secondary electrode 15
upon the carbon button 12 may be adjusted with much delicacy and accuracy.
The elastic pressure-device may be used as shown in Figure 6, in which the
numeral 19 denotes a pivotal support depending from the ceiling or top, of the box,
from which hangs a lever 20, bifurcated, or having two parallel arms, between which
is arranged a spiral spring 21, its inner end made fast to a shaft 22, journalled in
the parallel arms of the lever, and provided with a ratchet 23, which is engaged by
a holding pawl 24, pivoted to the lever.
The shaft 22 is provided with a milled head, or button 25, lying outside the
lever, to enable the shaft to be turned. When these parts are used, the outer end
of the spiral spring is made fast to a stud 26 lying between the lever-arms and
rigid with one, or both, thereof.
The lever 20 is so placed that the back, or surface of the outer coil of the spiral
spring 21 is turned toward the diaphragm. Upon this portion of the spring is
mounted the secondary electrode of metal, or carbon, and having any preferred
form. As for example, a strip of carbon placed upon the spring coil, or a metal
diaphragm and a carbon button, mounted thereon, instead of the carbon strip.
To one arm of the lever 20 is attached a secondary, or.. auxiliary spring 27,

page_text: which diverges somewhat from the lever, and extends downward to make engage-
ment with the point of the set screw 17. It should be noted, however, that the
ratchet 23 and holding pawl 24 may be dispensed with, or omitted and the outer
end of the spring will, in such case, be cast loose, instead of being made fast to the
stud 26. When the said parts are present, however, it will be seen that, by
manipulating the milled head 25, the spiral spring 21 may be placed under greater
or less tension, thereby increasing, or decreasing, its power of elastic resistance.
This adjustment in combination with the regulation of the set screw 17, gives a
compound regulation of pressure and, when properly arranged, materially increases
the delicacy and accuracy of the transmitted pulsations.
The secondary electrode is connected to the primary of an induction coil, and
thence to the second pole of the battery, as usual, the secondary of the induction
coil being in the line, but this matter, as well as the method of making the line-
connection with the diaphragm, is subject to very considerable variation. The
wires enter the box and leave the same by the way of binding posts 28.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondents, I declare that what I claim is :-
First. A receiver for an electric telephone, having a permanent magnet of
substantially conical, or conoidal shape, substantially as described.
Second. A receiver for an electric telephone having a permanent magnet
consisting of a substantially cone-shaped, metallic shell, the smaller end thereof
having an exterior cylindrical form, while the conical shape is preserved, interiorly,
throughout substantially as described.
Third. In a receiver for an electric telephone, the combination with an outer
shell or bandle, of a cap having an interior, concave surface, a permanent magnet
composed of a metallic shell having an interior conical face its smaller end being
thickened gradually by making a portion of the exterior face cylindrical, an induc-
tion coil mounted thereon and a diaphragm between the thickened end of said
magnet and the concave face of the cap, substantially as described.
Fourth. In a receiver for an electric telephone, the combination with a handle of
a cap closing one end and having an inner, concave face, a perforated diaphragın
between the cap and the end of the handle, a permanent magnet consisting of a cone-
shaped metallic shell, open at both ends and having its smaller end next the
diaphragm gradually thickened and an induction coil mounted thereon, substantially
as described.
Fifth. In a receiver for an electric telephone, the combination with a shell, or
handle, having a cap closing one end and a diaphragm between the two, of a
permanent magnet consisting of a cone-shaped shell, the large open end having a
collar receiving screws, or bolts and an ear-piece screwed upon the open end
of the handle through which screws or bolts are inserted, substantially as
described.
Sixth. In a receiver for an electric telephone, the combination with a shell or
handle having a diaphragm at one end, of a permanent magnet consisting of a cone-
shaped metallic shell having a collar on its larger end, an ear-piece, screwing upon
the said end of the handle, screws or bolts passing through the said ear-piece and
tapped through the collar on the magnet, and a set-screw tapped through an
external collar on the handle and abutting against the ear-piece, substantially as
described.
Seventh. In a telephone transmitter, a diaphragm consisting of a perforated
sheet, film or disc of suitable material coated or plated, with carbon substantially
as described.
Eighth In a telephone transmitter, a diaphragm composed of a sheet, film or
disc of suitable material, having openings and coated, or plated with carbon,
substantially as described.
Ninth. In a telephone transmitter, a diaphragm composed of a reticulated, or

page_text: foraminous sheet, disc or film, such as wire netting or gauze having a coating
or plating of carbon and provided with a carbon button, substantially as
described.
Tenth. In a telephone transmitter, the combination with a diaphragm of a
secondary electrode, a spiral spring on the outer coil of which said electrode is
mounted, a lever having a shaft to which the inner end of the spring is made fast
and a stud holding the outer end of the same, said shaft having a ratchet and a
stop pawl engaged with it, a secondary or auxiliary spring having one end attached
to the pivoted lever, and a set-screw, adapted to bear against the free end of said
secondary spring, substantially as described.
Eleventh. In a telephone transmitter, a diaphragm consisting of a film of suitable
material, enclosed by a substantially homogeneous strongly coherent body of carbon,
substantially as described.
Twelfth. In a telephone transmitter, the combination with a diaphragm having
a central carbon electrode, of a pivotally suspended frame behind the diaphragm,
composed of vertical, parallel arms, a spiral spring having one end mounted on a
revolvable shaft supported by said arm, and an adjustable support having a set
screw bearing on a spring rigidly mounted on the pivotally mounted frame,
substantially as described.
Dated this 2nd dow of Fabr 1902
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.