IMPROVEMENTS IN ELECTRIC TELEPHONES
Year: 1885

page_text: I, CHARLES ELMER ALLEN, of Adams, in the County of Berkshire, in the State
of Massachusetts, United States of America, Electrician, do hereby declare the nature
of my said invention for "IMPROVEMENTS IN ELECTRIC TELEPHONES," 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 Electric Telephones and has for its object the provision
of a simple and effective transmitter which when used will produce upon an
ordinary receiver of the Bell or any other type a very decided and marked increase
in the volume, strength and intensity of tone thus enabling me to transmit speech
or other sounds over a long distance without increasing the battery power.
To produce this effect I employ as part of the electric circuit a body of con-
ducting material in a solid, or in a loose free state such as pulverized, powdered or
granulated carbon. I place this material in a chamber with non-conducting walls
and provide a platinum plate at bottom and another at top thereof. The bottom
plate is fixed when in use but is adjustable to increase or diminish the compactness
of the free carbon or to enlarge or lessen the capacity of the carbon chamber. The
plate on the opposite end of the body of carbon is free to vibrate thereupon and
has a post for connection with the diaphragm.
When the diaphragm is vibrated by the sound waves, the vibrating platinum
plate is moved correspondingly against the free carbon. This causes the con-
ductivity of the pulverized mass to vary and a consequent variance of the working
strength of the current passing through the instrument in agreement with the
sound waves.
•
The vibrating platinum plate or disc is held against the diaphragm by a
delicately adjusted spring so as to cause it to respond to the slightest vibrations of
the diaphragm and to quickly follow the outward movement thereof. The con->
nection between the spring and the post or part of the platinum plate with which▸
it makes contact is platinum covered so as to make it sensative to the electric
contact and although the pressure of the spring against the post is continuous yet
this pressure varies in unison with the vibrations of the diaphragm and aids in
varying the working strength of the current.
A modified form of mouth piece for collecting sound and intensifying it by:
resonance may be employed in lieu of the small mouth piece in ordinary use,
4+0

page_text: The accompanying drawings illustrate what I consider the
carrying my invention into practice.
Dest Шеаць
Figure 1 is a central longitudinal section of my improved device.
Figure 2 is a plan view with the mouth piece and diaphragm removed.
Figure 3 is a detail showing the connection to one of the line posts.
Figure 4 is a section of a mouth piece and diaphragm in which the ring used
upon the diaphragm in Figure 1 is omitted.
Figure 5 shows in detail a modified form of connection between the spring and
contact post.
Figure 6 represents a sectional view of the modified form of mouth piece.
Similar letters of reference indicate corresponding parts in all the figures where
they occur.
A is a cylindrical body formed of hard rubber or other insulating material. This
body is provided with a central longitudinal opening and a top recess in which the
diaphragm vibrates. The mouth piece A* is secured upon the top of the body A
and the diaphragm B is held in place between the mouth piece and the body, as
will be more fully explained hereinafter.
The longitudinal central opening in the body A forms a carbon chamber a and
also affords a means for securing the lower platinum plate or disc C. This plate
or layer C of platinum is secured upon the top of the metallic plug C¹ which fits
snugly in the central opening and with the platinum plate upon it forms the base
of the carbon chamber. An enlarged head C2 upon the bottom of the plug C¹ (by
means of which head the plug C₁ is operated by a screw driver or any suitable
tool) is screw threaded on its periphery and as shown engages with internal screw
threads in a metallic cylinder D which is also screw threaded exteriorly and
engaged with threads on the interior of the enlarged lower part of the central
opening in the body A. The insertion of this sleeve D enables me to make the
threads on the head of the adjusting plug very fine. Above the plate C in the
chamber a is placed the the conducting material Z which is powdered, pulverized
or granulated carbon or similar low conductor in a loose free state. By properly
adjusting the plug C₁ this chamber a may be made smaller or larger and the carbon
be more or less compressed.
Above the mass of powdered or granulated carbon Z is placed the disc E having
the platinum plate e fastened upon its under side for contact with the carbon.
The disc E is connected to a post which has a point on its top bearing against a
button b, loose or fixed on the under side of the diaphragm.
A spring F secured at the outer end directly or indirectly to the body, rests
under the shoulder f¹ on the post f and keeps it pressed against the diaphragm
and throws the plate E e away from the mass of granulated carbon. The opening
in the spring plate F through which the post f passes is large enough to allow free
motion.
In order to regulate the tension of spring F a set screw G let through the
body A and operated from below the same as the plug 02 01 bears under the plate
or spring E between its two ends. By means of this screw the tension of spring F
under shoulder ft is increased or diminished to produce the desired pressure of
post against the diaphragm, also to increase or diminish the promptness with
which the platinum plate E will follow the diaphragm in its outward movement,
and to aid in regulating the compression or tension of the powdered or granulated
carbon attendant upon the movement of the disc E in harmony with the vibrations
of the diaphragm.
In order to protect the parts and make the instrument less liable to disorder and
accidental change of adjustment I provide a cap A¹ of insulating material which
fits upon the lower end of body A and covers and protects the otherwise exposed
parts. This cap A¹ is held in place by being screwed upon the extended screw
threaded end of the sleeve D which projects beyond the body A for this purpose.
A diametrical opening a* is formed in the cap A¹ for the insertion of a bar or rod.
T

page_text: to aid in unscrewing said cap in case it gets, stuck. The upper interior corner of
the cap A is cut away, or bevelled 'as shown at a² to admit of easy attachment of,
the connections to line without danger of breaking said connection by unscrewing:
or replacing the cap.
1 ¦
For security the outer end of spring F is secured upon an arc of metal. F which
is fastened to the rubber body, A.
The top of body A has an annular ridge or rim A² as shown in Figure 1 and the
diaphragm B is provided with a ring B¹ on its under edge which ring fits over the
rim A and centers the diaphragm upon the? instrument; insuring the proper
connection between the point of the post f and the button on the diaphragm.
T
7.
This rim A and ring B may however be dispensed with and the simple
construction shown in Figure 4 employed.
The form of and connection between the spring F and post of may be varied, as
shown in Figure 5 two pins f³ may be used in place of the collar f¹ and the hole
in plate or spring F may be opened entirely to the end making a slot as shown.
Stops 88 may be provided upon the spring to prevent the post from turning too
far around.
Whether formed with the collar and closed hole as shown in Figure 1 or with
the pins and open hole as shown in Figure 5 the points where the post and the
spring touch each other are covered with platinum for the purpose of aiding the
variance of the working strength of the current as before explained. I have used
solid carbon instead of pulverized with good results.
✗, Figure 6, is a concentrating attachment to be placed upon the instrument in
lieu of the mouth piece A*, and Y, is the collector and resonator which is employed
in connection with the part X. The flaring mouth piece y¹, collects the sound, the
rear wall y³, gives resonance by reflection and the tube y³, conveys it to the con-
centrating attachment X which delivers it upon a small central portion of the
diaphragm thereby producing a good effect and enabling the instrument to collect
and transmit sound when made at a distance from it.
The circuit through the instrument is as follows: From line post H, through
wire h, sleeve D, plug C², C¹, C, granulated carbon Z, disc e, E, post f, spring F,
arc F¹, connection i, screw I, to line post J. This circuit also includes the primary
of an induction coil, the secondary of which goes to line in the ordinary way.
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. The combination with the diaphragm and a body or mass of conducting
material in a loose, pulverized or granulated state of a connecting piece touching
the diaphragm and the mass or body and a spring to cause the connecting piece to
promptly follow the diaphragm and release its pressure upon the mass.
2. The combination with the diaphragm connecting or contact piece, and the
retracting spring provided with an adjusting screw of the mass or body of con-
ducting material in a loose, pulverized or granulated state.
3. The combination with the mass of pulverized or granulated conducting
material vibrating platinum plate provided with a post for connection with the
diaphragm and a spring for throwing the platinum plate away from the mass, said
post and spring being provided with platinum covered portions where they touch
each other to aid in varying the working strength of the current as set forth.
4. The combination with the diaphragm contact piece and retracting spring of
the mass of pulverized or granulated conducting material, the adjusting plug C² C¹
provided with the platinum top and the threaded metal sleeve D as set forth.
5. A case for transmitters consisting of the body A having the longitudinal
central opening with the screw threaded sleeve D extending beyond the end of the
body and the cap A' for screwing upon the sleeve and covering the parts in
combination with the diaphragm and electrodes as set forth.

page_text: <
6. The combination with the diaphragm of the transmitter of metallic electrode
contact pieces as those formed by the end of the spring and the pin on the post,
making electrical contact with each other independent of the diaphragm contact
and a carbon electrode as set forth.
7. The combination with the diaphragm and resistance devices of the collector
and resonator Y having the tube y³ and the concentrator X substantially as and for
the purpose set forth.