IMPROVEMENTS IN ELECTRIC TELEPHONIC TRANSMITTERS
Year: 1884

page_text: COMPLETE SPECIFICATION.
I WILLIAM BEALE HALE of Washington in the District of Columbia and
United States of America, Patent Solicitor, do hereby declare the nature of my
" and in
invention for IMPROVEMENTS IN ELECTRIC TELEPHONIC TRANSMITTERS
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:-
My invention relates to improved means for varying the contact between the
current varying electrodes in that class of electric telephonic transmitters commonly
known as "variable contact" telephones or microphones.
The main object of the improvement is to cause electrical currents having an
extended range of variation to traverse a main line as the effect of sounds and to
cause the reproduction of such sounds loudly and clearly in one or moro receiving
telephones in such main lines.
This object is accomplished primarily by causing the variations of the diaphragm
of such a transmitter to act mechanically upon the opposite contacting electrodes
through intermediate levers in such manner as to intermittingly press said
electrodes against each other with a movement corresponding to the vibrations of
the diaphragm but of greater amplitude whereby is effected an extended range of
variation of contact between said electrodes and a consequent and corresponding
extended range of variation in the current on the circuit in which said electrodes
are included.
A further object is to cause the vibrations of the diaphragm, amplified in
transmission to act through mechanical connections upon the opposite contacting
current varying electrodes in such manner as to alternately and positively increase
and relax their pressure toward each other in contradistinction to the hitherto
practiced mode of increasing the pressure positively and allowing the relaxation to
occur by the recession of one electrode.
Another object of the invention is to cause the diaphragm to act upon the
opposite contacting electrodes in such manner through intermediate mechanisin as
to vary the area of their contacting surfaces in direct proportion to their variations
of pressure.
The invention consists in certain novel combinations of devices and modes of
operation which will be hereinafter particularly described with reference to the
accompanying drawing in which

page_text: Fig 1 is a vertical section of the case, mouthpiece and diaphragm of a trans-
mitter constructed according to my invention the interior parts being shown in
full lines.
Fig, 2 is a top view of the contacting current varying electrodes.
The letter X indicates the enclosing casing having in its front wall a circular
aperture x in front of which a diaphragm A and mouthpiece a are secured in the
usual manner.
Within and upon the bottom or floor of the casing stand two metallic
standards E and E¹ the former having its upper end curved slightly toward the
diaphragın To the top of this standard is pivoted a lever C having a long arm
extending upward and a short arm downward from its pivot while to the top of
standard E is pivoted the lower extremity of an upwardly projecting lever C.
These levers have fastened to their tops respectively the electrodes K and K¹ which
have their facing surfaces beveled wedgelike and in lapping contact with each other
These electrodes are preferably made of carbon such as is used for battery plates
and other electrical purposes and aro held in yielding contact with each other by
the elasticity of the metallic levers CC when they are lapped and the levers
upright as shown. These levers are held upright by being pivotally connected
with the prongs b and b¹ respectively of a forked arm B projecting from and
secured to the center of the diaphragın A.
The prong b is the longer of the two and is pivoted to the lower end of the short
arm of lever C while the prong b' is pivoted to a non-conducting lug n rigidly
fastened to the lever C between its pivot, and its upper or electrode bearing end.
The arm B is split horizontally for a portion of its length from its forked end as
shown at s in order that the forks band b' may be sprung slightly away from
each other under strain and resume their normal positions when the strain is
removed.
Power for moving the levers C and C₁ is applied through the prongs b and b
and as the lovers are connected or linked together by tho prongs and arm B thoy
must move simultaneously In the present instance the lever C is of the first class
and the lever C¹ of the third class and when the arm B is moved in the direction
of the arrow the prongs will swing the lovers C and C¹ so that their electrodes
at their upper ends will be passed toward each other end wise and their wedgeliko
shape causes increase of pressure between them as they are thus moved as well as
an increase of their lapping surfaces When the arm B moves in the opposito
direction, a reverse movement of the electrodes takes place with a corresponding
decrease in their pressure and lapping surfaces.
Now it will be readily understood that when these electrodes are included in an
electric circuit and are pressed toward and from each other as described the variation
of their contact due to both variations of pressure and of lapping surfaces will so vary
the resistance of the circuit as to cause great variations in the quantity of electric
current passing thereover and if these variations of current correspond to vibrations
of a diaphragm under the influence of sounds similar sounds will be produced by
receiving telephones in circuit with the electrodes. Any of the known forms of
magnetic telephones may be operated in such a circuit.
The letter D designates an induction coil such as commonly used in transmitters
of this class. One terminal of the primary circuit of this induction coil is connected
with the metallic standard E¹ by a wire w and the other terminal is connected by
a wire w¹ with one pole of a local battery Y having its other pole connected with
the standard E by a wire w². The terminals of the secondary circuit of the
induction coil are respectively connected to binding posts p and p¹ to the former of
which may be connected a line wire as shown at L, and to the latter a ground wire
Any other known mode of connecting a transmitter for use may be employed.
Now when words are spoken or other sounds produced in the vicinity of the
diaphragm A said diaphragm will be set in vibration thereby and such vibrations
causing longitudinal vibrations of arm B will be transmitted through said arm its
prongs and the levers C and C to the electrodes K and K' causing alternate increase

page_text: and decrease of their pressure against each other and alternate increase and accicas
of their lapping surfaces with the result that a receiving telephone in the main
line as shown, for instance at T, will promptly and clearly reproduce the sounds
made at the transmitter as already explained.
The levers move simultaneously in opposite directions at their upper ends under
control of arm B and therefore both increase and relaxation of the pressure and
increase and decrease of lapping surfaces of the electrodes are the result of positive
actions and the variations of current resulting from both halves of each vibration
of the diaphragm are as nearly equal as are said half vibrations themselves, a
greater variation being thus produced than when one electrode follows another on
its return half-vibration,
It will be understood that the tips of prongs b and b¹ move in small arcs, and
it is to allow them to follow these ares that the arm B is split. The prongs might
of course be made slightly elastic and the split omitted.
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 an electric telephonic transmitter the combination with a diaphragm of
levers carrying contacting electrodes, and mechanical connections by which the
vibrations of the diaphragm aro made to cause the levers to press said electrodes
against each other with varying force substantially as described.
2. In an electric telephonic transmitter the combination with a diaphragm of
levers carrying contacting electrodes at their free ends and mechanical connections
through which the vibrations of the diaphragm are made to cause the levers to
press said electrodes against each other with varying force substantially as
described.
3. In an electric telephonic transmitter the combination with a vibratory
diaphragm and two lovers carrying contacting carbon electrodes at their free ends
said electrodes being in the primary circuit of an induction coil, of intermediato
mechanical connections through which the vibrations of the diaphragm cause
the levers to press said electrodes against each other with varying force
substantially as described.
4. In a transmitting telephone and in combination with the diaphragın thereof,
two resistanco varying electrodes mounted upon swinging arins and mechanical
means for causing the simultaneous approach and simultaneous recession of said
levers by the movement of the diaphragm substantially as described.
5. In combination with resistance varying electrodes supported upon levers and
maintained in constant electrical contact with each other, a diaphragm and
intermediate mechanism so arranged and combined that the movement of the
diaphragm in a given direction shall cause the simultaneous approach of the
electrodes in proportion to the amplitude of the motion of the diaphragm
substantially as described.
C. In an electric telephonic transmitter the combination with a vibratory
diaphragm and two pivoted levers having free ends provided with electrodes
inaintained in elastic contact with each other of an intermediate link connecting
said levers and arranged to cause the pressure of either electrode in one direction
to produce an opposite pressure of the other electrode and suitable mechanical
means for transmitting the vibrations of the diaphragm to said levers substantially
as described.
7. In an electric telophonic transmitter the combination with a diaphragm and
two electrodes in the piimary circuit of an induction coil having its secondary
circuit arranged for connection in a main line of two countermoving lovers arranged
to press said electrodes against each other simultaneously with varying force in
response to the vibrations of the diaphragm substantially as described.
8. In an electric telephonic transmitter the combination with a diaphragm and
two contacting electrodes in the primary circuit of an induction coil having its
secondary circuit arranged for connection in a main line, of two levers connected

page_text: to move simultaneously in opposite directions at their free ends which support said
electrodes respectively and means for mechanically transmitting rocking motion to
said levers from the diaphragmn when the latter vibrates essentially as set forth.
9. In an electric telephonic transmitter the combination with a vibrator arranged
to vibrate in response to sound vibrations of the air and two contacting electrodes
of two lovers of different classes supporting said electrodes respectively, and
mechanism connecting said levers and vibrator whereby said levers are caused to
press the electrodes against each other with varying force in response to the
movements of the vibrator substantially as described.
10. In an electric telephonic transmitter the combination with a vibrator
arranged to vibrate in response to sounds produced in its vicinity and two contacting
electrodes lapping each other in the direction of their motion and included in an
electric circuit of two levers having mechanical connection with said vibrator and
arranged to be operated thereby for alternately pressing said electrodes toward
each other and causing their pressure and contacting surfaces to be increased
simultaneously substantially as described.
11. The combination with the wedge-like electrodes and means for pressing their
beveled surfaces together with elastic force of means for transmitting motion from
the diaphragm of a telephonic transmitter to both of said electrodes for sliding
them alternately in opposite directions substantially as described.
12. The combination with the pivoted elastic levers having at their free ends
respectively the lapping wedge contact electrodes of the diaphragm and intermediate
mechanical connections whereby amplified vibration is communicated therefrom
through the levers to the electrodes substantially as described.
13. In an electric telephonic transmitter the combination with a diaphragm and
two resistance varying electrodes of two re-actionary levers operated by the
diaphragm for pressing said electrodes against each other substantially as described.
14. In a telephone re-actionary levers arranged to press resistance varying
olectrodes against each other, in combination with a diaphragm and suitable
intermediate devices whereby motion is transmitted from the diaphragm to the said
levers for varying the pressure of said electrodes substantially as described.
15. In a telephonic transmitter the combination of the diaphragm with two
electrode carrying re-action levers and mechanical connections between the same
and with the diaphragm substantially as set forth.