Year: 1887

page_text: 1, WERNER GENEST of 14 Neuenburger Strasse Berlin Germany Engineer do
hereby declare the nature of this invention to be as follows:-
Microphones as heretofore constructed can only be used when the instrument is in a
certain position because the contact appliances generally are under the influence of
gravity and thus can only act properly when in a certain position. Such contact
appliances are also influenced by every vibration of the membrane or diaphragm so
that not only the vibrations produced by the words spoken and the like, but also those
produced from other causes produce variations in the contact appliance of the instru-
iment which often make themselves so strongly noticeable as disturbing noises in the
receiver that it is impossible to understand the telephonic communication.
According to my invention I obviate these defects by subjecting the contacts to a
certain braking action so that the pressure wherewith the movable part of the contact
is pressed against the one on the diaphragm is only dependent upon the adjustable
pressure or tension of a spring and the pressure of contact hence is inade more or less
independent of gravity. A microphone thus constructed may therefore be used in any
position and for instance be combined directly with a telephone which is placed against
the ear.
Experiments made with such a microphone have proved that by suitable
choice of induction rollers the spoken word may be clearly conveyed to a distance of
over a hundred miles.
One form of the instrument may be as follows. The contact appliance consists of a
carbon cylinder provided at each end with gudgeons which rest in carbon bearings in
the electrical circuit. These bearings or blocks are fixed to the diaphragm which is
held in a casing consisting of two parts. By means of a spring the carbon cylinder is
pressed against the diaphragm so that the gudgeons press against one side of their
bearings.
When a person speaks against the diaphragm it is vibrated in the direction of the
pressure of the spring and only the variations of the pressure between the gudgeons
and its bearing exert an influence on the electric current. A movement or shaking of
the diaphragm in other directions will not alter this contact pressure, whether the
diaphragm is placed vertically or horizontally in any other position.

page_text: The spring may in this arrangement be flat and fixed at one end to the inside back
of the casing and also fixed in its acting part to a strip of metal which by means of a
screw can be adjusted so as to give the spring the required power or pressure. In
this way the pressure of contact between the carbon cylinder and one side of its
bearings can be adjusted as required. The spring may where it is in contact with the
carbon cylinder be covered with felt india-rubber or other elastic or soft material in
order that it may not partake of the vibrations of the cylinder.
Although I have described one form of apparatus I do not limit myself to such, as
the apparatus may be made or constructed in many different ways. The spring need
for instance not act directly on the cylinder but on an intermediate stiff piece of metal,
wood or other suitable material. The means for setting up or adjusting the spring
may also vary greatly so long as its pressure is vertical to the diaphragm. Also
instead of one cylinder I may use two or more in conjunction with one common
spring or with a plate or bar acted upon by a spring. The form of the movable
contact piece may be a body of prismatic or other form instead of a cylinder.
Dated this 5th day of October 1887.

page_text: I, WERNER GENEST of 14 Neuenburger-Strasse, Berlin, Germany, Engineer 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:-
Microphones as heretofore constructed can only be used when the instrument is in a
certain position because the contact appliances generally are under the influence of
gravity and thus can only act properly when in a certain position. Such contact
appliances are also influenced by every vibration of the membrane or diaphragm so
that not only the vibrations produced by the words spoken and the like but also those
produced from other causes produce variations in the contact appliance of the
instrument which often make themselves so strongly noticeable as disturbing noises in
the receiver that it is impossible to understand the telephonic communication.
According to my invention I obviate these defects by subjecting the contacts to a
certain braking action so that the pressure wherewith the movable part of the contact
is pressed against the one on the diaphragm is only dependent upon the adjustable
pressure or teusion of a spring and the pressure of contact hence is made more or less
independent of gravity. A microphone thus constructed may therefore be used in
any position and for instance be combined directly with a telephone which is placed
against the ear. Experiments made with such a microphone .have proved that by
suitable choice of induction rollers the spoken word may be clearly conveyed to a
distance of over a hundred miles.
One form of the instrument is shewn in the accompanying drawing Figures 1 and 2
being vertical sections at right angles to each other, Figure 3 a plan and Figure 4 a
detail view. The contact appliance consists here of a carbon cylinder a provided at
each end with gudgeons o which rest in carbon bearings 6 in the electrical circuit.
These bearings or blocks are fixed to the diaphragm d which is held in a casing
consisting of two parts A and B. By means of a spring f the carbon cylinder a is
pressed against the diaphragm d so that the gudgeons o press against one side of their
bearings in the direction of the arrow on Figure 1, as shown more clearly in the
sectional detail view Figure 4, the two gudgeons o resting against definite parts of the
holes in the carbon blocks b.
When a person speaks against the diaphragm d it is vibrated in the directions of
the double arrow y Figure 4. As the cylinder a is influenced in the direction of the
arrow by the pressure of the spring fit follows that only the variations of the
pressure between the gudgeons o and the bearing blocks b caused by the vibrations of
the diaphragm d in the direction y exert an influence on the electric current flowing
through these parts. A movement or shaking of the diaphragm d in other directions
will not alter this contact pressure, whether the diaphragm is placed vertically or
horizontally or in any other position.

page_text: The spring preferably made of two parts fand f¹ may as shown at Figures 2 and 3
in this arrangement be flat and fixed at one end at 7 to the inside back of the casing B
and also fixed in its acting part to a strip of metal g which by means of a screw h can
be adjusted so as to give the spring the required power or pressure. In this way the
pressure of contact between the carbon cylinder a and one side of its bearings 6b can
be adjusted as required. The spring finay where it is in contact with the carbon
cylinder a be covered with felt india rubber or other clastic or soft material in order
that it may not partake of the vibrations of the cylinder.
Although I have described one form of apparatus I do not limit myself to such as
the apparatus may be made or constructed in many different ways. The spring need
for instance not act directly on the cylinder but on an intermediate stiff piece of metal,
wood or other suitable material. The means for setting up or adjusting the spring
may also vary greatly so long as its pressure is vertical to the diaphragm. Also
instead of one cylinder a I may use two or more in conjunction with one common
spring or with a plate or bar acted upon by a spring. The forin of the movable
contact piece may be a body of prismatic or other form instead of a cylinder. The
form of the diaphragm and casing is not of importance.
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
First Constructing microphones with a movable contact body or bodies provided
with gudgeons placed in bearings fixed to the back or under side of the diaphragm,
said body being influenced by adjustable elastic pressure vertically to the diaphragm
so that the gudgeons are pressed against one side of the bearings only for the purpose
of exerting a braking influence on the diaphragm and thus avoiding vibrations other
than those intended to be produced in the use of the instrument substantially as set
forth.
Second The carbon body a having gudgeons o mounted in holes i in the carbon
blocks which latter are fixed to the back or under side of the microphone diaphragm d,
the body a being elastically pressed against the diaphragm by an adjustable spring f,
substantially as described and shewn.