Improvements in Microphones.
Year: 1896

page_text: Date of Application, 30th June, 1896-Accepted, 8th Aug., 1896
COMPLETE SPECIFICATION.
Improvements in Microphones.
I FRANZ STOCK, Engineer, of Zeughofstrasse 6 and 7, Berlin, S.O. in the
Empire of Germany, 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 :-
This invention is intended to unite the advantages of the carbon roller micro-
phones (constancy in sound effect) with those of the carbon powder microphones
(great sound strength) whereby the inconveniences which are characteristic to
these two kinds of microphones are nearly completely avoided.
The nature of this new construction of the microphone is as follows:-
If circular carbon discs of the microphone are provided with bores and a round
carbon stick is put through the latter to carry the discs, there is obtained a series
of contacts by placing a vertical carbon vibrating membrane or diaphragm against
the periphery of the carbon discs; the density of these contacts depends from the
manner in which the discs are pressed downwards. On speaking against the
membrane the discs begin to vibrate and simultaneously begin a slow but regular
rotation round their suspension point. This circumstance distinguishes the present
microphone in an advantageous manner from the roller microphones in which the
rolling of the rollers must be hindered by a damping means. With the slow but
regular revolution of the discs is connected the essential advantage that the
touching places remain free from dust, which circumstance also effects favourably
the clearness of the language.
The before mentioned objects can be executed in different ways according to the
number of the single carbon discs as well as of the carbon sticks provided with
carbon discs.
One method of performing this invention is represented in the annexed
drawing:-
Two carbon sticks a, a' reposing in a frame R of ebonite or a similar material
carry each six carbon discs b, b, b and b, b, b', the edges of which are cylindrical.
The discs are kept separated by projections upon the carbon sticks or by interposed
discs or by any other convenient means.
In Fig. 2 is represented the combination of the discs with the membrane M.
The ebonite framing R which carries the carbon sticks a, a with the discs b, b' is
solidly connected with the microphone casing, whilst the membrane M. fixed in the
rings can be pressed more or less against the carbon discs by means of an
appropriate arrangement whereby the pressure between the discs and the membrane
can be charged at pleasure within certain limits.
The rings are fixed by means of the screws s in the cover D. The latter is
screw threaded in order to be screwed into the casing G, until the membrane M
has obtained the desired contact position. By setting up the screw t the latter is
then fixed.
The communication of the microphone with the primary current is effected in
such a manner that the current enters at one, for instance, the upper carbon
stick a, passes through the (for instance six) carbon discs 6 lying in parallel com-
munication to the membrane M and from here on the under discs and passes out
finally through the lower carbon rod a'.

page_text: Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1. A microphone the contact bodies of which are formed by carbon rings b, b¹
suspended loosely upon carbon sticks a, a' and placed against the conductive
adjustable sound plate M and adapted on vibration to make a rotatory movement
so that always new contact places are brought into touch.
2. A microphone as described in Claim I in combination with a device regulating
the position of the sound plate M and consisting of the rings r which fix the sound
plate M and which are fixed by means of screws s on the screw threaded cover D
and the screw t fixing the latter.
Dated this 30th day of June 1896.
HERBERT HADDAN & Co.,
18 Buckingham Street, Strand, London, W.C.,
Agents to Applicant.