Year: 1898

page_text: Date of Application, 1st June, 1898
Complete Specification Left. 25th Feb 1899 Accented 22nd Ann
1000
I, JOSEPH BERLINER, of No. 18, Kniestrasse, Hanover, in the Kingdom of
Prussia and Empire of Germany, Electrician and Manufacturer, do hereby
declare the nature of this invention to be as follows:-
The object of the present invention is to produce a microphone which is highly
sensitive and in a high degree capable of transmitting the received sounds.
One electrode is formed by a block of carbon, the other by the membrane
itself. The electrical connection between the two is effected by means of small
balls of carbon or any other suitable material. The circuits are made in the
usual manner, that is by means of a battery and induction coil, in normal state
the balls are slightly pressed against the membrane and against grooves cut in
the block of carbon. These grooves are of an elliptical section, such section
having been found to give the best effect. The distance between the block and
the membrane is about half the diameter of the balls.
For avoiding self-tuning the membrane is composed of three layers cemented
together, one of carbon, a second a paper and a third of mica, the layer of carbon
having the purpose of effecting the electrical connection. The advantage
obtained by the use of elliptical grooves as compared with others, of cylindrical
and semi-circular shape, was found by experiments. The probable reason is
that for elliptical sections the pressure is less than for circular ones, and that
in cylindrical grooves the pressure is too small to have any effect at all. Be-
sides this the elliptical section allows of placing a larger number of balls in the
grooves and consequently of increasing the number of conducting points. In
spite of the increased depth there is a conical action of the groove for every
ball, that is if the balls get nearer to the block the pressure is increased.
The membrane of carbon in combination with a stiffening material allows
an extremely light construction and avoids self-tuning such as is produced by
membranes of metal or membranes in which a block of carbon is cemented to
the membrane.
Any other suitable material-may be used instead of paper or mica, but these
materials are preferable.
The block may be made of several parts either connected electrically or in-
sulated, the electric connection in the latter case being produced by the mem-
brane itself. In this case the electric current coming from one block passes one
set of balls, the membrane and the other set of balls and returns to the other
block. The blocks may be secured to the casing independently of each other
or they may be connected with each other by means of an insulating material.
The number of grooves may be increased to increase the sensibility of the
instrument.
Dated this 1et dow of Im 1000
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the 'Applicant.

page_text: Improvements in Microphones.
1, JOSEPHI BERLINER, of No. 18, Kniestrasse, Hanover, in the Kingdom of
Prussia and Empire of Germany, Electrician and Manufacturer, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:
The object of the present invention is to produce a microphone which is highly
sensitive and in a high degree capable of transmitting the received sounds.
Referring to the accompanying drawing:-
Figure 1 is an elevation of the carbon electrode.
Figure 2 is a transverse central section thereof, and,
Figure 3 shows a section of my improved microphone with its electrical
connections.
One electrode is formed by a block of carbon (C), the other by the mem-
brane (M) itself being of conducting material. The electrical connection
between the two is effected by means of small balls of carbon (K) or any other
suitable material. The circuits are made in the usual manner, that is by means
of a battery (B) and induction coil (E), in normal state the balls are slightly
pressed against the membrane and against grooves cut in the block of carbon.
These grooves are of an elliptical section, such section having been found to
give the best effect. The distance between the block and the membrane is about
half the diameter of the balls.
For avoiding self-tuning the membrane may be composed of three layers cemented
together, one of carbon, a second of paper and a third of mica, the layer of carbon
having the purpose of effecting the electrical connection. The advantage
obtained by the use of elliptical grooves as compared with others, of cylindrical
and semi-circular shape, was found by experiments. The reason is
that for elliptical sections the pressure is less than for circular ones, and that
in cylindrical grooves the pressure is too small to have any effect at all. Be
sides this the elliptical section allows a larger number of balls to be placed in the
grooves and consequently to increase the number of conducting points. In spite
of the increased depth there is a conical action of the groove for every ball,
that is if the balls get nearer to the block the pressure is increased.
The membrane of carbon in combination with a stiffening material admits of
an extremely light construction and avoids self-tuning such as is produced by
membranes of metal or membranes in which a block of carbon is cemented to
the membrane.
Any other suitable material may be used instead of paper or mica, but these
materials are preferable.
The block may be made of several parts either connected electrically or in-
sulated, the electric connection in the latter case being produced by the mem-
brane itself. In this case the electric current coming from one block passes one
set of balls, the membrane and the other set of balls and returns to the other
block. The blocks may be secured to the casing independently of each other
or they may be connected with each other by means of an insulating material
The number of grooves may be increased to increase the sensibility of the
instrument.

page_text: Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what I
claim is:-
A microphone with one or more blocks of carbon, either insulated or connected
electrically, and provided with grooves of elliptical section for receiving balls
of carbon, substantially as described.
his 25th day of February 1899.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.