An Improved Telephone.
Year: 1888

page_text: Date of Application, 7th Sept., 1888
Complete Specification Left, 7th June, 1889-Accepted, 13th July, 1889
An Improved Telephone.
I, JACQUES PAUL ZIGANG, Captain of Infantry, of 30 Boulevard St. Germain, Paris,
in the Republic of France, do liereby declare the nature of this invention to be as
follows:-
My invention relates to telephones ordinarily used for receiving and reproducing
audibly messages transmitted from a distance.
My improved telephone consists of a very small horse shoe electro magnet of
soft iron wound' with insulated wire of one tenth to two tenths of a millemêtre in
section according to the resistance of the outer circuit. The extremities of the two
poles are rivetted into a bar of copper by which the electro magnet is fixed into
the interior of the instrument, the bar of copper being sufficiently heavy to prevent
the molecular vibrations caused by the alternate partial magnetization and
demagnetization from being communicated to the wooden mount of the telephone.
The insulated wire coils are also coated with a thick covering of.shellac varnish, and
by their inertia prevent longitudinal vibrations which might interfere with the proper
action of the poles upon the armature.
The electro magnet is contained in a hollow case or handle of hardwood having at
one end a circular opening about 15 millimêtres in diameter, and at the other end
a small opening for the passage of the conducting wires from the coils.
A ring
or washer of wood is screwed against the larger end of the case and holds the edge of
the diaphragm firmly against the latter.
The diaphragm itself consists of a disc of copper about 3 of a millimêtre thick
and 18 millimetres in diameter having fixed to its centre a small rectangular piece of
soft iron of a millimêtre thick, and of a size large enough to cover the ends of the
two poles. The diameter of the vibrating part of the diaphragm is about 15 milli-
mêtres but it may be increased up to 22 millimêtres in instruments in which greater
resistances require the use of bobbins for the. coils.
The two ends of the insulated conducting wire are carried away to the required
distance in a flexible cord.
The electro-magnet is held firmly by the crossbar in a recess in the open end
of the case, so that when the diaphragm is in its proper position and the electrical
current passes through the coils the distance between the soft iron armature and
the poles is as small as possible without actual contact.
The improved telephone works in the primary circuit of an electric current in
which varying resistances are caused by means of a carbon microphone in the usual
way. If mounted in metal the result is even more satisfactory; the vibrations of the
diaphragın are effective to their full extent, the support remaining inert by reason of
its relative mass.
The telephone is particularly adapted for domestic purposes.
1004

page_text: manner the same is to he performed to be particularly described and ascertained in
and by the following statement and accompanying drawings, (that is to say)
:-
Telephones for domestic use have not come into general use, on account of the size
and cumbrousness of those ordinarily used, as well as their high price. The receiving
instruments are generally clumsy and inconvenient to hold often requiring the users
to rest on their elbows to avoid the fatigue caused by the weight of the masses
of metal contained in them. The instruments are still in fact of the primitive type
of those of Bell, having a permanent magnet, voluminous coils in order to act
effectively upon the heavy poles, and a diaphragm of large diameter and carried in a
heavy frame of similar dimensions.
By my present invention, I obtain a telephone, simple, light, cheap, and occupying
little space, which nevertheless gives a clearness of articulation, and a loudness equal
or superior to the instruments, ordinarily used.
I have found by numerous experiments that when an undulating electric current
acts upon a telephonic diaphragm by means of an electro magnet having poles of soft
iron, the sounds produced are, within certain limits, more intense and clear in proportion
as the elasticity of the diaphragm is greater and its diameter less.
This is attributable to the use of a resonator of small capacity giving a high pitch
to the fundamental tone proper to the instrument, a condition very favourable to the
propagation of the sounds produced in it.
In the accompanying drawing, which, is in illustration of my invention, and
represents a telephone constructed upon tho principle just explained, Figure 1 is a
longitudinal section through the apparatus; Figure 2 a front view of the diaphragm
and its armature; and figure 3 a front view of the instrument, with the diaphragm
and the cover or ring B₁ removed.
The improved telephone consists, first, of a small electromagnet A about one and a
half millimetres diameter, having two soft iron poles, round which are wound
insulated wires of from one to two tenths of a millimetre in section, according to the
resistance of the outer circuit.
The two ends of the poles are rivetted into a strip of copper or brass A¹ (figures 1
and 3) by which the electro magnet is fixed into the outer case. This strip is
sufficiently heavy to prevent any molecular vibrations caused in the poles by their
partial magnetization and demagnetization, from being conveyed to the wooden case.
The insulated wire coils are covered with a thick coating of lac varnish which gives
them such rigidity that by their inertia, together with that of the brass strip, any
longitudinal vibration which would prevent the poles from acting effectively upon the
armature is prevented. Second, of a hollow hard wood case B having at one end a
circular opening about fifteen millimetres diameter, and at the other end a small hole for
the passage of the cord containing the conducting wires. Third, of a flat ring B' of the
same hardwood, which holds the diaphragm in its place by means of three screws.
Fourth, of an armature plate or diaphragm C (figures 1 and 2) of brass about three
hundreths of a millimetre thick, and eighteen millimêtres diameter, having fixed at
its centre a small rectangular piece of soft iron about fifteen hundredths of a milli-
mêtre thick and sufficiently long to cover the ends of the two poles. The diameter
of the vibrating portion of the diaphragm is fifteen millimetres, but it may be
increased up to twenty two millimêtres in apparatus requiring longer coils by reason
of the length of the circuit.
The two ends of the insulated wires are connected to the conducting wires in a
flexible cord. The electromagnet is held by the strip in which its poles are carried
and which is fitted into a rebate or groove round the open mouth of the case, of
such depth that when the diaphragm is in its place and a current is passing through
the coils, the space between the armature and the poles is as small as possible without
their actually touching.
The parts of the improved telephone arc, on account of their small dimensions,
very well adapted to the successive magnetizations and demagnetizations produced by
the variations of resistance in the transinitting instrument; and speech is consequently

page_text: reproduced with greater purity and intensity than have yet been obtained in similar
instruments.
In my improved telephone the loudness of speech is sensibly proportioned to that
of the electric current, so that the greatest effect may be obtained by using coils of
suitable resistance.
The telephone forms part of a primary circuit, the variations of the electric
current passing through it being caused by a carbon microphone transmittor.
If mounted in metal it gives still better results, the vibrating movements of the
diaphragm being capable of full development, whilst the case romains inert on account
of its mass.
My improved receiving instrument possesses many advantages when used for
domestic purposes, and on circuits of some kilomêtres long. It is very light, its
weight not exceeding twelve to fifteen grammes; and consequently its manipulation
is very easy and entails no fatigue; the outer end is smooth and even and does
not, when applied to the car, produce the disagreeable sensation caused by metallic
receivers.
It may replace the magnetic telephone wherever the latter is used with a voltaic
current in a primary circuit, as is most frequently the case over moderate distances.
By its use light and easily handled micro telephonic apparatus can be applied in all
houses for connecting the door porter with the occupiers, or the servants with the
latter, or for other like purposes.
It is also well adapted for the exchange system used in towns between subscribers,
especially as it is not influenced (as in magnetic telephones) by induction from
neighbouring telegraphic or electric-light currents. Singing and music are so
perfectly reproduced by it, that it can be used with great advantage for hearing
theatrical or operatic performances. At the same time it is lighter and cheaper than
any other existing telephonic receiver:
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be perforined I declare that what I
I claim is :-
The domestic telephone constructed as described and shewn in the drawing.
2000
th day
of June 1889.
EDWARDS & Co.,
35, Southampton Buildings, London, Agents for the Patentee.