Improvements in and relating to Microphonic or Telephonic Transmitters.
Year: 1891

page_text: Date of Application, 11th June, 1891
Complete Specification Left, 26th Mar., 1892-Accepted, 30th Apr., 1892
PROVISIONAL SPECIFICATION.
Improvements in and relating to Microphonic or Telephonic
Transmitters.
I. ARTHUR THOMAS COLLIER, of Bondi, Caterham Valley, in the County of
Surrey, Gentleman, do hereby declare the nature of this invention to be as
follows:-
My invention relates to microphonic or telephonic transmitters, and is designed
to improve the construction and increase the efficiency of the same.
An important feature of my said invention is the suspension or support of one of
the carbon or other contacts, or of one set of such contacts in such a manner that
the said contact or set of contacts is self-adjusting, that is to say, the said contact
or set of contacts is capable of angular movement so that it can freely alter its
position relatively to the other contact or set of contacts, and thus ensure uniformity
of pressure between the contacts throughout the entire operative surfaces thereof,
and, at the same time, avoid jarring by separation of the said contacts while the
transmitter is in use.
For this purpose, I find it advantageous to connect one of the contacts or sets of
contacts. with a suitable support by means of a gimbal or a universal-joint of any
suitable description. Or I otherwise so arrange the said contact or set of contacts
that, if the other contact or set of contacts should bear against it more heavily at
one point than at another, it will alter its position so that the whole of the operative
surfaces of the contacts will be held together with uniform pressure, that is to say,
the force exerted to press together the contact surfaces at any one point will not
be greater than the force exerted to press them together at any other point. I can
thus provide for ensuring the contact of as great a number as practicable of the
molecules of the carbon or other material of which the contacts are composed,"
thereby greatly augmenting the efficiency of the transmitter. By these means,
moreover, I provide an unyielding back contact or inner contact or set of contacts,
which is nevertheless capable of angular movement for the purpose above
specified.
The said back contact or set of contacts, being capable of change of position
as above mentioned, will follow the return or outward movements of the diaphragm
by reason of the attraction exerted between the electrodes under the action of the
current, thus avoiding separation of the contacts or electrodes and the jarring
consequent thereon.
Hitherto it has been usual to employ contacts the operative surfaces of which,
are of small area, but, by my improvements, am enabled to employ contacts of
comparatively large area, or to employ two sets of contacts each comprising two
or more contacts, whilst ensuring uniformity of pressure between the contacts
throughout the whole of their operative surfaces, or between all the contacts of the
two sets thereof.
Instead of employing a gimbal or a universal-joint, I sometimes mount the said
contact or contacts upon a flexible or elastic diaphragm.
My present invention is advantageously applicable to microphonic or telephonic
transmitters, such as are described in the Provisional Specification filed with my
Application No. 8386 dated 15th May 1891, wherein the diaphragm is suspended
or supported in such a manner that, when the support is adjusted about a horizontal
axis, the said diaphragm will be moved by gravity so as to bring the contacts
together or to vary the pressure between the said contacts. My present invention
is, moreover, also applicable to other forms of transmitters.
I find it advantageous to place cushions of india-rubber, or other suitable material

page_text: between the support for the self-adjusting contact or set of contacts and the case
of the instrument to which it is secured.
When I employ a gimbal in combination with the said contact or set of contacts,
the current may be conducted through the screws which form the pivots for the
rings of the gimbal.
Dated this 10th day of June 1891.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.
Improvements in and relating to Microphonic or Telephonic
Transmitters.
1, ARTHUR THOMAS COLLIER of "Netria" Brickett Road St. Albans in the
County of Hertford, Gentleman, 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 :-
My present invention is designed to increase the efficiency of microphonic or
telephonic transmitters, and for this purpose I suspend or support one of the carbon
or other contacts or one set of such contacts in such a manner that the said contact
or set of contacts is self adjusting, that is to say, the said contact or set of contacts
is capable of angular movement so that it may freely alter its position with any
alteration in the position of the other contact or set of contacts, and thus ensure
uniformity of pressure between the two contacts or sets of contacts and avoid the
jarring sounds which are produced in the receiver by the separation of the contacts
whilst the instrument is in use.
The means for such suspension or support may be gimbals or a universal joint of
any suitable description, or, I may mount the said contact or contacts upon a flexible
or elastic support.
The contact or set of contacts mounted as herein before described may be advan-
tageously employed in combination with a diaphragm suspended or supported in
such a manner that, when the support is adjusted upon a horizontal pivot, the
diaphragm will be controlled by gravity so as to bring the opposite contact or
contacts mounted thereon into uniform pressure with the aforesaid contacts, this
pressure being capable of variation. My improvements may also be applied to
other forms of instruments.
The accompanying drawings illustrate in what manner my invention may be
carried into practical effect and I will proceed to fully describe my improvements
with reference to the various figures thereof, in each of which similar parts or
details of construction are indicated by similar letters of reference.
and
Figure 1 is a sectional side view of the instrument;
Figure 2 is a back view of the suspended diaphragm ;
Figure 3 is an elevation of one method of mounting the back electrode ;
Figure 4 is an alternative form of the arrangement represented by Figure 1;
Figure 5 is a back view of the diaphragm and electrode represented by Figure 4;
Figure 6 is an elevation of the back electrode shewn in Figure 4.
In Figures 1, 2, and 3 a part of the apparatus is represented as being broken
away in order to bring the drawings within reasonable limits.
A and B are the front and back portions respectively of the casing of the
telephonic transmitter, the mouthpiece C being formed through the front portion A
of the casing.
In the arrangement illustrated by Figures 1, 2, and 3, the back contact or
electrode P, is mounted upon a tubular stud Q, which is fixed upon the cross bar
of the inner ring of the gimbals R, the outer ring of which is supported by the

page_text: bars S S upon the studs T T fixed to the back of the casing. For the purpose of
preventing the transmission of extraneous vibrations to the back contact P, the
gimbals may be mounted upon indiarubber plugs, equivalent to the studs T.
In the modification illustrated by Figures 4, 5, and 6, the back electrode consists
of a series of points U mounted upon a carbon or metallic base V which is secured
upon the back part of the casing by means of three or more spiral springs W. In
this case the gimbals are omitted, and the essential amount of yielding motion.
without bodily displacement, is ensured by the springs. In substitution for these
springs, an indiarubber ball, or soft indiarubber plugs, or any other similar suitably
flexible and yielding support for the back electrodes may be employed.
In each of the modifications represented by the drawings the front contacts or
electrodes are shewn as being upon a suspended diaphragm D, which may be of thin
metal or of wood or of any other suitable material, secured upon the annular
framing E, which is suspended by the rod F from the pivot H by the arm G. The
front contact M is secured upon the diaphragm by means of the short tubular
stud N, which is secured upon the dome shaped flanged-metallic base O, which
in turn is secured upon the inner face of the diaphragm by cement rivets or other
suitable means.
The rod F by means of which the diaphragm is suspended as well as the annular
framing E of the diaphragm, are preferably metallic for the purpose of obtaining
a desirable amount of inertia, and the diaphragm may in some cases be damped by
means of a spring or springs secured upon the framing E and pressing upon the
central part of the diaphragm. The rod may also be protected by an indiarubber
tube drawn over it as indicated in Figures 1 and 4.
The electric eircuit is completed through the gimbals, the front and back
contacts, the framing E, the rod F, and the arm G, or otherwise so that the two
contacts are included in the circuit.
The contacts in all cases should be constructed of close grained hard homogeneous
carbon, and they preferably consist of two tablets as indicated by Figure 1, or of
one tablet and a set of carbon points, as shewn by Figure 4, the tablet being
attached to the diaphragm as shewn or alternatively being the back contact.
The two contacts are normally pressed together slightly by placing the point of
suspension of the diaphragm slightly behind a vertical plane passing through the
point of contact, and it will be obvious that the amount of this pressure may be
varied by altering the position of the point of suspension relatively to the vertical
plane. For this purpose I may employ a fixed screw and wing nut I, and an inclined
plane J formed on the inner upper surface of the hollow arm G, in combination
with a perforated wedge piece J capable of sliding on the fixed screw. When the
wing nut is turned in one direction or the other, the arm G will be lifted or lowered
around its pivot H, and by this angular movement of the point of suspension, it is
caused to recede from or approach the before mentioned vertical plane and thus
effect the adjustment of the pressure between the contacts. A spiral spring
may be placed on the fixed screw behind the wedge to force it into constant
proximity with the nut.
A sheet of indiarubber K may be secured upon the diaphragm by the elastic
ring L for the purpose of preventing the condensation of moisture from the breath
thereon.
may
The diaphragm instead of being suspended as hereinbefore described, be
carried on the front of the casing as in the well known Blake transmitter.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is :-
:-
1. In a telephonic transmitter, a back contact or electrode mounted on gimbals ;
substantially as and for the purpose described and as illustrated by the accompanying
drawings.
2. In a telephonic transmitter, a back electrode mounted upon a support capable

page_text: of angular displacement without yielding bodily; substantially as herein before
described and as illustrated by the accompanying drawings.
3. In a telephonic transmitter, the combination and arrangement with a back
electrode mounted on a support constructed to render the electrode capable of
angular movement without bodily displacement, of a front electrode or electrodes
mounted upon a suitable diaphragm; substantially as herein before described and
as illustrated by the accompanying drawings.
Dated this 25th day of March A.D. 1892.
WILLIAM E. HEYS,
Agent for the Applicant.