Improvements in Microphones.
Year: 1899

page_text: Date of Application, 15th Nov., 1899-Accepted, 30th Dec., 1899
COMPLETE SPECIFICATION.
Improvements in Microphones.
We, JULIUS EGGER, of 7, Huszar utca, No. 7, and ANTON POLLAK, of 7, Elisa-
bethring, 45, Hotel Royal, both of Budapesth, in the Kingdom of Hungary,
Director and Electrician respectively, do hereby declare the nature of this in-
vention 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 a granular carbon microphone in which the piece of
carbon or the like employed as the electrode, which is influenced in the ordinary
manner by means of a stud or pin from the centre point of the diaphragm assumes
the form of a horizontally elongated and vertically narrowed strip. This strip
is embedded in the upper layers of the grains of a box or chamber not entirely
filled with grains in such a way that only the, most sensitive layers of grains are
influenced when speaking.
In the accompanying drawings:-
:―
Figure 1 is a horizontal section, and
Figure 2 a vertical section of a microphone made in accordance with the
present invention.
a is the diaphragm, 6 the pin attached thereto, ca strip of carbon attached to
the other end of the pin. This strip is imbedded in carbon powder e located in
a casing d, whilst f is a carbon plate provided with recesses and excrescencies
which preferably have a horizontal direction, g is a washer of felt or like material
preventing the escape of the carbon dust from the box or casing d.
As may be seen in the drawing the oscillations or vibrations of the pin h
of the diaphragm a are transmitted to the strip c which in turn acts on the carbon
powder.
Any crumbling carbon or dust locates itself in the lower part of the casing d
without covering the carbon strip c or the carbon plate f.
The electrical connections are arranged as usual, that is to say one pole is con-
nected with the diaphragm and the other with the carbon plate f.
It may be seen from the drawing without further explanation that in this
microphone only a vertically thin and in fact the most susceptible layer of the
carbon powder is acted on, which circumstance is of the greatest importance
as the lower parts of the column of carbon powder being subject to the pressure
of the layers lying above them, the susceptibility of the under layers is reduced.
By the carbon strips c having in a vertical direction a small dimension, but in
a horizontal direction a somewhat large one, the result is attained that only the
upper layer of the carbon powder is exposed to the influence of the diaphragm
oscillations. This layer remains however permanently easily movable, as a
jamming and balling or caking together of the separate particles of carbon
cannot take place as they are not exposed to the pressure. The result of this
is not only an extremely great susceptibility in this microphone, but also that
the said great susceptibility is permanently maintained.

page_text: Having now particularly described and ascertained the nature of our said in-
vention and in what manner the same is to be performed, we declare that what
we claim is--
A granular microphone in which the piece of carbon (e) or the like which is
used as one electrode, is connected by means of a pin (b) with the centre point
of the diaphragm (a) characterised by the said piece of carbon (c) or the like
having the form of a strip elongated in a horizontal direction, but narrower in
a vertical direction, which, is imbedded in the upper layers of the grain in a not
completely filled box or chamber of grains with the object of causing the oscilla-
tions or vibrations of the diaphragm to influence the most susceptible layers,
substantially as hereinbefore set forth.
Dated this 14th November 1899
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicants.