Improvements in Microphones.
Year: 1896

page_text: Date of Application, 25th Mar., 1896-Accepted, 16th May, 1896
COMPLETE SPECIFICATION.
Improvements in Microphones.
I, PAUL HARDEGEN of 49 Ritterstrasse, Berlin, in the Empire of Germany,
Manufacturer, do hereby declare the nature of this invention and in what
manner the same is to be perforined, to be particularly described and ascertained
in and by the following statement :-
This improvement relates to microphones and consists essentially in the insertion
of an elastic or soft and non-conducting body between the microphone diaphragm
and an electrode in such a way that without preventing the vibration of the
diaphragm an automatic vibration of the electrode elastically attached to or
pendent from the diaphragm takes place in a vertical and horizontal direction, and
a free mobility of the carbon powder, grains or the like contained between the
diaphragm and the electrode is obtained, and thereby any setting or caking of the
carbon powder, or the like, is prevented, with the object of obtaining, as far as
possible, an exact reproduction of the tones or sounds.
This invention is shown in the accompanying drawings, in which,
Figure 1 is a longitudinal section;
Figure 2, a diagram showing by arrows the various capabilities of vibration of
the diaphragm and the electrode elastically connected therewith, and
Figure 3, a view of the electrode employed in this apparatus, which is shown as
an example in longitudinal section.
The arrangement of the diaphragm and the electrode and of the carbon powder
or the like employed with them, does not form any part of this invention as such
may be of any ordinary kind.
The diaphragm m, Figure 1, carries at its centre an electrode k of such materials
(for instance, carbon, metal or the like) as conduct electricity which is connected
to said diaphragm by means of a non-conducting elastic or soft substance f (such
as, for instance, soft felt, woollen material, wadding or the like). This body fis
attached to the diaphragm m and to the body k at the points c and d by means of
a suitable adhesive substance, for instance, shellac, gum, isinglass, fish glue, or
the like.
An opening o, Figure 3, is arranged in the electrode k, through which opening
the ordinary fine or disintegrated particles e (for instance, grains, fibres, dust, balls,
or the like, of carbon, metal or metallic substances), are inserted, the quantity
necessary for good working being so regulated that the capability of vibration of
the diaphragm m and the electrode k is not affected. The opening o may be closed
by means of a screw s, for instance, which simultaneously serves for connection of
the wire b for conducting the electric current.
The diaphragm m is connected in the ordinary manner, for instance, by means of
a wire a with a source of electricity.
The hereinbefore described elastic attachment of the electrode k to the
diaphragm m, renders it possible to obtain a peculiar and hitherto unattainable
capability of many sided vibration of the electrode (Figure 2) as the latter does
not merely follow the vibrations of the diaphragm (which take place in a horizontal
direction) simultaneously, and to an equal extent, but vibrates in a vertical and also
in a diagonal direction, as shown by the arrows in Figure 2. By this elastic
attachment of the electrode k to the diaphragm m, as great or varied a capability
of oscillation as possible of the two above mentioned parts m and k, and also of the
soft or flexible part 1, placed between them, is attained, and any compression,
caking, or packing of the carbon grains, metallic particles, or the like e, Figure 1,

page_text: contained between the diaphragm and the electrode, is prevented. Whilst this
adjustable packing e can freely move, it is also so constantly shaken up that it can
never set fast but must constantly circulate.
Apart from the two advantages of manufacture arising from this arrangement, a
reproduction as exact as possible of the tone not only in strength but also in quality,
is attained by the hereiubefore described arrangement.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
:claim is :-
1. The improvement in microphones which cousists in the insertion between a
Euitable clectrode (k) and the diaphragm (m) of an elastic or soft non-conducting
body (f) (made for instance of felt, woollen material, wadding, or the like), said
elastic or soft body (f) being attached to the diaphragm (m) and to the electrode (k)
by means of a suitable adhesive substance (such for instance as shellac, gum,
isinglass, fish glue, or the like) whereby a great capability of vibration, in several
directions, of the diaphragm and the electrode connected therewith is obtained, as
well as a free mobility and circulation or constant alteration of position of the
ordinary granular or like material (e) (such for instance as carbon, metal, metallic
bodies or the like) contained between the electrode and the diaphragm substantially
as described.
2. In a microphone such as described, an electrode (k) having an opening (o),
(capable of being closed) for regulating the quantity of the ordinary granular or
like substance (e) (carbon or metallic particles or the like) inserted between
the diaphragm (m) and the said electrode or parts (f and k) attached to said
diaphragm, by which means the various capabilities of vibration of the
diaphragm (m) and the electrode (k) may be assisted or diminished substantially as
described.
Dated this 24th day of March 1896
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.