IMPROVEMENTS IN AND CONNECTED WITH TELEPHONES
Year: 1885

page_text: ROLAND HARRY RIDOUT 5 Napier Terrace Battersea Surrey Surveyor do hereby
declare the nature of my invention for IMPROVEMENTS IN AND CONNECTED WITH
TELEPHONES, to be as follows:-
According to the first part of my invention which has for its object the variation
in strength of an electric current in a manner corresponding with the intensity and
frequency of acoustic impulses I so construct a transmitter that the incidence of
such impulses properly directed upon it occasions friction between loose contact
surfaces included in some part or parts of an electric circuit and from the nature of
the contact surfaces employed consequent variation in the resistance of such circuit
and the strength of the current flowing therein and this result I effect in a variety
of ways by causing a part of the transmitter which vibrates in response to such
impulses to (a) move a lever connected to a hinge or joint constituting the necessary
contact surfaces (b) move a lever or rod terminating in and resting upon or
against one or more of the necessary contact surfaces (c) move a rod or lever with
suitable termination in a mass of powdered or granulated conducting material as
carbon the particles of which provide the necessary contact surfaces (d) move a
block having contact surfaces in proximity to another block fixed and having
contact surfaces also the said blocks being electrically connected by intermediate
conducting pieces suitably disposed and in some cases the said blocks are held in
suitable relative position to each other by enclosing in and attaching the same to
an elastic tube or by other equivalent means (e) move upon their axes rods or bars
in sockets each having the necessary contact surfaces.
According to the second part of my invention having a like object I so construct
a transmitter that acoustic impulses properly directed vary the resistance of a mass
of powdered granulated laminated or fibrous material contained in elastic tubes and
included in the circuit and this result I effect by causing a part of the transmitter
which vibrates in response to such impulses to vary the shape of the tubes as
by elongation compression or torsion. In some cases the incidence upon the tubes
themselves of such impulses effects the desired object.
According to the third part of my invention having a like object I attach to a
sounding board or diaphragm or equivalent part of a transmitter which by the
incidence of acoustic impulses is capable of vibration a stretched wire or wire under
torsional strain included in an electric cireuit & passing into or through a mass of

page_text: powdered granulated laminated or fibrous material also included in such circuit.
The effect of vibrations so communicated to such wire is to vary the strength of a
current flowing in such circuit in the manner sought.
According to the fourth part of my invention having a like object I so construct
a transmitter that the incidence upon it of acoustic impulses either occasions
friction in or alters or varies the relative position of loose contact surfaces enclosed
in elastic tubes and from the nature of the contact surfaces employed consequent
variation in the resistance of the electric circuit in which such contact surfaces are
included.
According to the fifth part of my invention having for its object the acoustic
insulation of the telephone or telephonic relay from its stand or case or the parts of
the telephone or telephonic relay from each other I employ in a state of tension or
compression cords bands rings or tubes or equivalent appliances of elastic material
of which india rubber is a good example to form supports for the instrument or
the parts of the same so to be insulated.
According to the sixth part of my invention I dispense with the diaphragm or
tympan which forms. an essential part of many transmitters as at present con-
structed and I establish with better results for the transmission of articulate speech
the necessary mechanical relationship between vocal utterances and the electric
circuit in which such utterances are destined to vary the resistance as follows.
A plate disc or cup is provided with an axial rod attached thereto the combination
being hereinafter referred to as a "piston and rod" and supported from the rod
and acoustically insulated from the case in the manner indicated in the fifth part
of my invention. The piston forms the surface upon which vocal utterances or
other acoustic impulses are directed and the rod communicates with the resistance-
varying part of the electric circuit.
According to the seventh part of my invention having for its object the better
reproduction of sounds in a telephonic receiver or relay whether otherwise improved
by my invention or not I construct the diaphragm or tympan which forms a part
of many such instruments as follows (a) by forming it of two discs of membranous
or other material having like qualities for the object in view superposed with an
intervening space filled with powdered or granulated material of which amongst
others hard carbon and pumice stone are useful examples. The two discs are held
together at their center or at intervals over their surface. The diaphragm thus
constructed is provided with an armature or not according to the form of instry-
ment in which it is used and the whole secured in any suitable manner. Such a
diaphragm in vibrating causes a motion among the contained particles which much
improves and augments the resulting sounds (b) by forming it of hard steel or
other suitable material and supporting at intervals along the edge in a ring or cage
of hard material of which amongst others steel and glass are useful examples, The
diaphragm so formed and supported. is held in tension by the use of a spring
magnet or other equivalent device.
According to the eighth part of my invention having for its object the better
transmission and reproduction of vocal utterances or other sounds by instruments
whether otherwise improved by my invention or not I improve the magnet which
forms an essential part of many such instruments by making its polar terminations
of less than half the cubical contents of an equal length of its body. Amongst
other shapes for such polar terminations I find the following useful (a) a solid
cylinder with conical rounded flat or cupped end (b) a cone truncated or otherwise
(c) a hollow cylinder.
According to the ninth part of my invention having a like object I employ with
the magnet which forms an essential part of many such instruments a fixed
armature of iron or steel preferably perforated at one part for the insertion of the
polar termination of but free of contact with such magnet-the other part of
armature may be in contact with magnet or not. The diaphragm or disc con-
stituting the vibrating armature is placed in front of the magnet as usual and the
improvement results from the diaphragm vibrating in a magnetic field restricted
v.

page_text: and intensified by the means indicated and also from the coil of wire upon the
polar termination of the magnet being in propinquity to such fixed armature. It
follows that a similar result will be attained if one polar termination of a magnet
is shaped to answer the purpose of the fixed armature to the other.
According to the tenth part of my invention having for its object the improve-
ments of instruments whether otherwise improved by my invention or not for the
reproduction of vocal utterances or other sounds in which a magnet and diaphragm
form essential parts I so construct and dispose the parts of such an instrument that
the polar terminations of a magnet carrying coils of wire as usual may approach an
iron or steel disc attached to a membranous diaphragm in such manner that either
but not both at the same time may be in contact therewith. In some cases I find
it convenient to employ two magnets with a like pole of each presented to the disc.
In any case the coils are so joined up that the passage through them of. an electric
current would either vary the attraction of the disc as a whole or tend to its
Oscillation about a point between the poles.
According to the eleventh part of my invention having for its object the improve-
ment of the induction coil which usually forms part of a transmitter whether
improved by my invention or not I construct the core of the same of discs of iron
or steel sometimes with radial slits or of a thin sheet of the same materials rolled
into a more or less solid cylinder or of filings of the same materials agglomerated
together preferably by nonconducting material or contained in a suitable case.
For all the purposes of my invention I find carbon a suitable material for the
construction of the contact surfaces herein referred to.

page_text: One form is shown in Fig. 1. A is a diaphragm or tympan. A cylinder or
prism Crests by one end in a fixed grooved block D and at the other is jointed
axially to A in such manner that when A vibrates its motion is transmitted along
the axis of C (One simple form of joint to connect A and C may be made as follows
but I do not regard such joint as a feature of my invention. A is composed of or
carries at its center a disc of material capable of magnetic induction perforated
with a small hole at its center. The proximate end of C consists of a small cylin-
drical magnet and. rests in the hole in A." The attraction between C and A. is
sufficient to cause C to partake of A's motion) In a modification of this part of
my invention the block D is fixed to the center of A and C is jointed at the destal
end to a fixed support E. In a further modification of this part of my invention
two grooved blocks are employed one being fixed to A and the other to E-C resting
upon D D.
And a yet further modification of this part of my invention is shown
in Fig. 2. Here the blocks D D are connected by the spiral springs S. S. and the
latter thrown into tension by the former being hooked on to A and E respectively.
By this arrangement the axial position of D Ď relatively to A is secured. C rests
by its ends upon D D as before. It will be obvious that without departing from
the spirit of my invention D may when desired consist of a hollow cylinder or
prism and C may consist of a simple rod wrought into a knob where it rests upon
and makes contact with such hollow cylinder or prism.
I find that the friction of C upon D effected as described very efficiently varies
the strength of a current flowing through C. D. Such variations of current strength
being utilized for the purposes of my invention by means well known and under-
stood by electricians.
According to the 2nd part of my invention I acoustically insulate a telephone
or telephone relay from its case or the parts of such instruments from each other
as follows. Fig. 3 shows one application to the horizontal modification of the
improved transmitter described in letters patent granted to me and numbered 9274
of 1885 and is intended to insulate the telephone from its case. Here T is the
telephone and K, K, K, are studs secured to the case. These studs carry an elastic
band G, preferably of india rubber and T is supported upon G in any suitable
manner. Referring again to my previous invention the vertical transmitter therein
described may be insulated from its case according to my present invention by
forming the straps H H of india rubber.
Fig. 4 shows the further application of acoustic insulation to the transmitter
described according to my present invention and shown in Fig. 1. Here I. I. and
I¹ I are two rings of india rubber tube and serve to insulate the diaphragm A
(which is contained between them) from the case. The block D is insulated from
the case by being supported in 3 or more cords (two only of which are shown) M. M.
It occurs in the use of many of the ordinary forms of transmitters that the voice
occasions vibrations in some part not intended to be affected by it. By the method
of acoutic insulation herein described the injurious effect upon articulate trans-
mission by such vibrations is lessened or entirely removed. It is obvious that
without departing from the spirit of it the details of this part of my invention
may be modified to meet other cases than those herein quoted-the one essential
condition being that when disturbed from rest the rate of vibration as a whole of
the part intended to be insulated shall be slow relatively to the vibrations which
are sought to be lessened or extinguished.
According to the 3rd part of my invention I support the diaphragm or tympan
of a telephone particularly of a telephone receiver at intervals along its edge
and not continuously between flanges according to the usual practice, In Fig. 5
✗ is a ring of hard material such as steel-its inner contour being coned. The
diaphragm F has 3 or more projections along its edges by which it rests in con-
tact with the cone, A fine wire or cord J is secured at one end to the center of F
and at the other to an adjustable support H. When in use F is held at intervals
along its edge in contact with X by the tension of J.

page_text: The 4th part of my invention relates to the construction of the diaphragm which
forms an essential part of many receivers. Here I take 2 discs of any suitable
material as horn iron or membrane and secure one on each side of a flat ring leaving
a small interval between the discs say between the limits of to inch and
tightly fill this space with some hard harsh material such as powdered pumice stone.
The discs are stitched or tied at intervals in their surface to keep the powder in
place. The effect of vibration upon such a diaphragm is to cause a disturbance
within the diaphragm itself & thereby augments the resulting sound.
In the accompanying drawings, Fig. 1 is a vertical section. Fig. 2 is a hori-
zontal section Fig. 3 is a plan. Fig. 4 is a horizontal section Fig. 5 is a section
and Fig. 6 is a plan.
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 A telephone transmitter operating with friction without change of pressure
upon contacts included in an electric circuit substantially as herein before described
and set forth with reference to Fig. 1 of the accompanying drawings,
2nd A telephone transmitter operating with friction without change of pressure
upon contacts included in an electric circuit substantially as hereinbefore described
and set forth with reference to Fig. 2 of the accompanying drawings,
3rd The combination of the parts A. C. D substantially as and for the purposes
herein before described & set forth with reference to Figs. 1 and 2 of the accom-
panying drawings.
4th In a telephone the method of acoustic insulation as and for the purpose
herein before described and set forth with reference to Figs. 3 and 4 of the accom-
panying drawings.
5th The method of constructing and supporting a telephone diaphragm substan-
tially as herein before described and set forth with reference to Fig. 5 of the
accompanying drawings,
6th A telephone diaphragm constructed and operating substantially as herein-
before described and set forth with reference to Fig. 6 of the accompanying
drawings.