Improvements in Telephonic Transmitters.
Year: 1891

page_text: Date of Application, 20th Aug., 1891
Complete Specification Left, 20th May, 1892-Accepted, 25th June, 1892
PROVISIONAL SPECIFICATION.
Improvements in Telephonic Transmitters.
I, ALEXANDER MARR of Repton Street Chorlton-upon-Medlock Manchester
in the County of Lancaster, Electrical Engineer, do hereby declare the nature of
this invention to be as follows:-
This invention relates to telephonic transmitters and its object is to increase
the sensitiveness of these instruments to vocal sound waves without at the same
time increasing their sensitiveness to extraneous sounds and vibrations.
According to these improvements I mount the diaphragm of the instrument in
any suitable frame or carrier and I suspend this frame or carrier in a suitable
box or casing by means of indiarubber cords or bands or by means of spiral
springs or other equivalent means which will act as buffers to any shocks which
would otherwise be transmitted from the box or casing to the diaphragm.
I prefer to employ two sets of indiarubber rings cords or bands, one of which
secures the diaphragm frame to the lower part of the instrument while the other,
by means of an adjusting screw, secures the frame to the upper part of the
instrument.
In order to provide for the adjustment of the amount of pressure between the
carbon or other contacts or electrodes, I may connect the diaphragm or its frame
by means of a diagonal link or spring with the back of the box or casing or I
may so connect it with two or more of such links or springs. When the
diaphragm is raised or lowered by means of the adjusting screw, the diagonal
position of the spring or link causes it at the same time to approach or recede
and consequently also to increase or diminish the pressure between the carbon
clectrodes or contacts.
One of the carbon electrodes or one set of such electrodes is mounted upon
the diaphragm, and the other in contact therewith upon a fixed or yielding
support. One or both of the electrodes or sets of electrodes and particularly
the back electrode may advantageously be mounted upon a disc or sheet of india-
rubber larger than the electrode, and this disc is cemented or secured to the
diaphragm or support as the case may be, by the edges alone, so that that part of
the indiarubber disc on which the electrode is mounted may be free to move
away from the diaphragm or support, and that all vibrations shall thus be trans-
mitted through a free part of the disc before reaching the electrode.
DAL of Aumunt A D 1801
WILLIAM E. HEYS,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Telephonic Transmitters.
I, ALEXANDER MARR of 9 Repton Street Chorlton-upon-Medlock Manchester
in the County of Lancaster, Electrical 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 :-
This invention relates to telephonic transmitters and its object is to increase the
sensitiveness of these instruments to vocal sound waves without at the same time
increasing their sensitiveness to extraneous sounds and vibrations.
According to these improvements I mount the diaphragm of the instrument in
any suitable frame or carrier and I suspend this frame or carrier in a suitable box

page_text: or casing by means of indiarubber bands or cords or by means of spiral springs or
by other equivalent means, which will act similarly, in preventing the transmission
of shocks and extraneous vibrations to the diaphragm. prefer to employ two sets
of the springs or rubber bands, one of which sets secures the diaphragm frame to
the lower part of the casing, while the other, by means of an adjusting screw,
secures the frame to the upper part of the casing.
In order to provide for the adjustment of the amount of pressure between the
carbon or other electrodes, I may connect the diaphragm or its frame by means of
a diagonal link or spring, with the back of the casing, or I may so connect it with
two or more of such links or springs. When the diaphragm is raised or lowered
by means of the adjusting screw, the diagonal position of the spring or link causes
it at the same time to approach or recede, and consequently also to increase or
diminish the pressure between the electrodes or contacts. If however the adjusting
screw be arranged horizontally, as hereinafter fully described, the same result may
be obtained without the diagonal links or springs, and, this arrangement being
simpler, I prefer to adopt it in all cases.
One of the carbon electrodes, or one set of such electrodes is mounted upon the
diaphragm, and the other, in contact therewith, upon a fixed or yielding support.
One or both of the electrodes or sets of electrodes, and particularly the back
electrode, may advantageously be mounted upon a disc or sheet of indiarubber
which may have a larger area than the contact area of the electrode, and this disc
is cemented or secured to the diaphragm or support as the case may be, by its
edges alone, so that that part of the indiarubber disc on which the electrode is
mounted may be free to move away from the diaphragm or support, and so that all
vibrations in the diaphragm or casing must be transmitted through a free part of
the disc before reaching the electrode.
The accompanying drawings illustrate in what manner I at present prefer to
carry my invention into practical effect.
In these drawings
Figure 1 is a vertical section through the instrument; and
Figure 2 a front elevation with the door removed.
Figure 3 is a sectional view of a modified arrangement of the electrodes drawn
to a larger scale.
In each of the figures in which the parts are represented, A is the casing of the
instrument; B the door in which the mouthpiece C is formed; D the diaphragm ;
EE the electrodes; F the diaphragm adjusting screw; G an adjusting screw for
the back electrode; and S S the rubber springs.
The diaphragm may be of sheet steel as in the well known Blake transmitter, or
of thin wood or other suitable material and may or may not be damped in the usual
way, as may be required. It is mounted in the frame H, to the upper and lower
ends of which the bars I I are connected. Below the frame, there is secured to
the casing a similar bar J, and the lower diaphragm bar I and the bar J are
connected by the elastic bands S or by equivalent springs, which should be
symmetrically arranged so that each of them bears as nearly as possible its exact
share of the total tension.
At the upper part of the casing there is a metallic bar or loop K which is
connected with the adjusting screw F in such a manner that the loop or bar must
partake of the longitudinal motion of the screw without its rotary motion. This is
most readily effected by mounting a free ring in a groove L formed just below the
head of the screw, and brazing the loop or bar to the ring. The loop or bar K is
connected with the upper bar I by means of the rubber bands S or by equivalent
springs, which should resemble the lower springs in strength number and arrange-
ment.
The adjusting screw F works in a nut M secured to the upper part of the casing
at the back of the diaphragm. It will be obvious that by rotating the screw in one
direction, the diaphragm will be caused to approach, and by rotating it in the other
direction it will be caused to recede from the back electrode.

page_text: If it be thought desirable to provide means for adjusting the tension of the
springs S S, the nut M, instead of being secured directly to the top of the casing,
may be adjustably secured upon a vertical slide. In like manner, the bottom bar J,
instead of being secured to the bottom of the casing, may be similarly secured upon
a vertically adjustable slide. It is preferred however to employ the arrangement
illustrated by the drawings, and to change the springs, if this should be found
necessary, for the purposes of correcting the tension.
The back electrode may be independently adjusted by means of the screw G, or
this screw may be omitted as represented by the partial view Figure 3. In this
case the back electrode may consist of three carbon points fixed in the brass or
metallic base N, which is cemented upon the rubber disc O. The rubber disc is
cemented by its edges or by one of its edges to the ring or carrier in which it is
mounted.
The front electrode preferably consists of a carbon disc having a central hole,
mounted upon a short light flanged tube as indicated by the drawings, the tube
being in turn mounted upon the diaphragm.
The electrodes are connected in the usual way with the instrument circuit or
circuits.
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. A telephonic transmitter constructed and arranged substantially as and for
the purpose hereinbefore described and as illustrated by the accompanying
drawings.
2. In a telephonic transmitter, a diaphragm suspended by indiarubber bands or
by equivalent springs, substantially as and for the purpose hereinbefore described
and as illustrated by the accompanying drawings.
3. In a telephone transmitter, a spring suspended diaphragm in combination with
means for adjusting the diaphragm relatively to the back electrode, substantially as
hereinbefore described and as illustrated by the accompanying drawings.
4. In a telephonic transmitter, an electrode mounted upon a disc of indiarubber,
the indiarubber being secured to the support by one or more of its edges only,
substantially as and for the purpose hereinbefore described and as illustrated by the
accompanying drawings.
Dated this 19th day of May A D 1892
WILLIAM E. HEYS,
Agent for the Applicant.