Year: 1885

page_text: I, CHARLES ELMER ALLEN, Electrician, of Adams, County of Berkshire, State of
Massachusetts, United States of America, 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 invention relates to that class of telephone transmitters in which the
variations of the current, flowing through the primary circuit, are effected by
varying the resistance of a mass of conducting or semi-conducting material,
included in said circuit; and has for its object the provision of an automatic
adjusting device for maintaining a constant, uniform normal pressure in said mass.
In an invention secured to me by British Letters Patent No 6689, and dated
June 2nd, 1885, I have shown and described a device upon which the present
invention is an improvement. In the present invention; I availed myself of some
of the features shown in that patent. To such features as I may use in common
in that invention and in this, I have added elements which render the transmitter
self-adjusting and capable of maintaining its proper adjustment for a great length
of time.
In addition to rendering the apparatus automatic in its adjustment, I have also
made the adjusting devices themselves adjustable to give greater or less pressure
upon the electrode or mass.
The pressure upon the mass is an upward gravity pressure possessing a con-
siderable degree of inertia.
By virtue of my construction I have overcome objections hitherto found in
gravity adjustments for granulated or pulverized carbon machines.
In all such machines two objects are desirable and necessary for producing loud
effects, or for long distance transmission.
One of these is that the pressure upon the mass shall be slight, and the other is
that one electrode (the mass) or the movable part connected therewith shall
possess considerable inertia.
The normal compression of the mass is maintained by force of the gravity
pressure and it continues sensative to and permits the ready vibrations of the
diaphragm; while by reason of the considerable amount of inertia offered by the
mass and its supporting mechanism, the variations in resistance are insured,

page_text: My invention embodies features which attain the objects above nained in a most
satisfactory manner, and render it capable of use with either granulated or
pulverized, or solid carbon, or any of the semi-conducting materials used as
electrodes for such purposes.
Another good effect which I attain is due to the fact that the electrode holder
or chamber is moved bodily in the adjustments, so that the mass of carbon whether
loose or solid, shall not be disturbed relatively to its support by the adjustment of
the latter, but shall be moved in mass therewith.
I also provide for automatically adjusting the contact plate or hard electrode
upon the carbon electrode without affecting the action of the post upon the
diaphragm, to which it is preferably rigidly secured, and render the movements of
the post entirely harmonious with those of the diaphragm and free from all undue
frictional and lateral influence of the retracting spring.
I also guard against undue friction between the edge of the contact plate and the
walls of the chamber.
By having the diaphragm and post rigidly connected, I avoid a slight rattle
which results from the separation of the diaphragm and post in loose connections,
when spoken to loudly. It also insures the faithful reproduction upon the carbon,
through the medium of the contact plate, of every movement of the diaphragm.
I have accomplished these objects and secured the good results due thereto, by
means of the construction and combination of parts hereinafter described and
claimed.
The accompanying drawings illustrate what I consider the best means for
carrying my invention into practice.
Figure 1 is an inverted view of the diaphram and support showing the
trunnioned shaft.
Figure 2 is a partial section and side elevation of the device.
Figure 3 shows a modification, and figure 4 is an enlarged view of the contact
plate and post showing the ball joint connections.
Similar letters of reference indicate corresponding parts in all the figures where
they occur.
Z is the body or frame of the device. A is the diaphragm mounted in it in any
suitable manner, preferably horizontal as shown. B is a post or connection which
rests under the diaphragm at one end and is connected to a contact piece, or hard
electrode B¹ at the other. A spring, C for causing the post B B¹ to promptly
follow the retraction of the diaphragm is mounted in the frame and adjusted by a
screw if desired as in my previous patent. The parts thus far described may be
the same as those shown in my patent already referred to.
Changes may, if desired, be introduced in the construction of the contact piece
or plate B¹, the manner of connecting the post B to it, and to the diaphragm, and
in the joint or connection between retracting spring and the post.
I have in this invention provided a packing of glove leather or kid, or some
other suitable material as shown at b*, figure 4, around the edge of the disc or
part B¹ which for this purpose is made thick or wide either by having a rim or
Alange set upon the disc as shown or in any other suitable manner. This packing
prevents friction between disc B¹ and walls of the carbon chamber.
I also provide a ball and socket joint as shown at b, same figure, between the
post B and disc B¹ to permit the latter to adjust itself upon the mass of carbon,
without affecting the position of the post.
A second joint of similar character is provided about midheight of the post as
shown at 6¹ figure 4, by forming a globular enlargement upon the post and setting
a seat or rest correspondingly channelled under said enlargement, in such position
as that the retracting spring C shall bear under it. This construction prevents
strains upon the position of the post by the action of the spring.
The post B is shouldered near its outer end and the extension beyond the shoulder
is screw threaded and projects through the diaphragm, where, as shown, it receives

page_text: the nut 6ª which binds the diaphragm and post together and causes every move-
ment of the former to be reproduced by the latter upon the mass of carbon, and
prevents the slight clatter that sometimes occurs in machines with loose connection
at this point when spoken to in a loud tone of voice. But the post may if desired
be applied against the diaphragm as in my previous patent.
The electrode chamber is formed in a holder D of metal or other heavy substance
and is of sufficient size to give it a considerable amount of inertia when suspended
in equilibrium or slightly overbalanced by a counterpoise. The mass of carbon. or
electrode lies in the chamber with the contact price B¹ upon it.
The holder D may be attached rigidly to a lever E and sustained and guided by
the movements of said lever, or may have guides as shown at e in figure 3, in
which case it is preferable to make the connection between lever E and block or
holder D loose as shown.
When constructed according to the plan shown in figure 3, I find it desirable to
make a deep seat in the bottom of the part D into which projects the pin d which
is fitted with knife edges on its ends to rest in the bottom of the seat at one end,
and in a step in the lever E at the other. The deep seat enables me to avoid
undue friction in the joint between the part D and guide e, as it allows the
pressure or power for adjusting the block to be applied so high up in the body of
said block or part D, as to avoid side strains, due to the necessarily curved path
taken by the end of the lever in its vertical movement, and the consequent
tendency to throw the block or holder D out of a true vertical path of motion
which arises when the lever is connected to the bottom of said chamber. The
loose form of connection afforded by the pin with knife edges on each end
contributes to this result also.
The lever E may be fulcrummed on knife edges or trunnions in any suitable
manner to avoid friction and secure easy firm movement as shown in Figure 3. As
shown in Figure 1, it is secured to the trunnion G which is supported at each end
in adjustable bearing g, g, let through brackets on the frame.
The lever E is provided with the adjustable counterpoise F, on its outer or free
end which is provided with a pinching or set screw as shown, to hold it at any
point on the lever and render the pressure or compression upon the mass of carbon
more or less, as may be desired.
When the connection between the part D and lever E are rigidly connected, they
are preferably made in a single piece as shown.
In both forms the side walls of the chamber in holder D are formed of insulating
material so that the circuit will be through the carbon.
The holder or block in both forms shown is moved bodily in making the
adjustments, the advantage of which has already been stated.
It is obvious that modifications may be made in the manner of applying the
gravity pressure, as well as in affecting the attachment near the top of the
holder.
The gravity lever may be supported in various ways, and I may use a ribbon
or spring secured at both ends supporting the lever with a torsional effect.
A considerable portion of the lever and carbon chamber may be detachable so as
to render it possible to lighten the parts for shipment.
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 telephone transmitter the combination with the diaphragm and an
electrode in contact therewith, of a mass of semi-conducting material held under
the electrode with a slight upward gravity pressure possessing considerable
inertia.
2. In a telephone transmitter the combination with the electrodes as described,
of a holder for one of them constructed and applied to give a slight upward
gravity pressure, and to possess considerable inertia.

page_text: 3. A gravity adjusting device having slight gravity pressure under the electrodes
and possessing considerable inertia.
4. A carbon or electrode holder for telephones having a gravity device, for
adjusting it bodily in a substantially vertical path as set forth.
5. A vertically movable carbon or electrode chamber or holder provided with a
pivoted and weighted lever as set forth.
6. The combination with the diaphragm, connecting electrode or contact piece,
and spring for accelerating their action, of a carbon electrode and a cavity adjusted
support therefor.
7. A gravity adjusting device for electrodes of telephone transmitters having the
point of attachment to the adjustable electrode near the same level with the point
of contact between the electrodes.
8. In a telephone transmitter the combination with the diaphragm and mass of
carbon of a post for contact with the diaphragm, and a contact plate for resting
upon the carbon having a universal joint between said post and plate.
9. In telephone transmitter the combination with the diaphragm, carbon and
chamber therefor of a connecting device working in said chamber having a
cushioned periphery, as and for the purpose set forth.
10. In a telephone transmitter the combination with the diaphragm and carbon
electrode of the electrode B¹, post B and spring C with a self adjusting joint
between the spring C and post B.
11. In a telephone transmitter the combination with the carbon electrode and
diaphragm of the connecting electrode or post and plate rigidly connected to the
diaphragm.
12. In a telephone transmitter the combination with the diaphragm and electrode
of semi-conducting material, of a post as B rigidly connected to the diaphragm and
a plate as B¹ having a universal joint between it and the post.