Year: 1887

page_text: I, HENRY HARRIS LAKE, of the firm of Haseltine, Lake & Co., Patent Agents,
Southampton Buildings, London in the County of Middlesex, 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 consists in an apparatus for transmitting vocal or other sounds
including articulate speech by means of a pulsatory current of electricity traversing a
conductor between distant stations. The term "pulsatory current" is here used in
contradistinction to the terms "undulatory current" and "intermittent current."
A pulsatory current is caused by suddenly increasing or suddenly diminishing the
intensity of the existing or normal current. An intermittent current is caused by
alternately breaking and establishing an existing current. An undulatory current is
produced by gradually increasing and diminishing the intensity of a normal current.
The distinction between the pulsatory and the undulatory current is fully set out in the
specification of Letters Patent to William Morgan Brown No. 4765, sealed the
15th May, 1877, and dated the 9th December, 1876.
It has been frequently maintained that articulate speech cannot be transmitted by
any electrical apparatus save through and by virtue of the undulatory current of.
electricity. The present invention is based upon the discovery that speech can be
transmitted by a pulsatory current of electricity, but is limited herein to the apparatus
for the purpose set forth. In another specification simultaneously filed herewith the
method and art of telephony through the employment of the pulsatory current is
separately claimed.
In the accompanying drawings Fig. 1 is a vertical longitudinal section on the
line of Fig. 3. Fig. 2 is a front view of the instrument. Fig. 3 is a horizontal
longitudinal section on the line zx of Fig. 1. Fig. 4 is a section similar to Fig. 1
showing certain modification in the construction.
Similar letters of reference indicate like parts.

page_text: A is a frame preferably of brass or other non inductive material. Said frame
consists of a circular portion B and an arm (extending therefrom. The part B has
a flange D in which is seated a diaphragm E which is made preferably of glass. Said
diaphragm is clamped in place by the mouth piece tube F. In the part B is an
elongated opening which exposes a portion of the rear side of the diaphragm.
The arm (supports the electro magnet G. H and I are the cores of said magnet and
J the yoke or connecting piece to which said cores are affixed and which is attached
to the arm C.
.
Upon the ends of the cores H and I are disposed the coils K and L. M is an
armature, pivoted in the forked end of the core I and provided with a downwardly
extending arm N which stands in proximity and parallel to the diaphragm E. Through
the arm N, and at a point opposite to the center of the diaphragm E, passes a screw 8,
the point of which may be disposed to make contact with said diaphragm.
1 and 2 are binding posts which are supported upon the arm C.
insulating material P are interposed between said posts and the metal of the support.
The circuit in the instrument proceeds from the binding post 1 through the coils K
and L and thence to the binding post 2, or vice versa.
Sleeves of
Attached to the rear side of the arm N is a coiled spring Q which extends rearwardly
through an opening in the core I and is connected to the end of an adjusting screw R
which passes through the core H. By suitable movement of the screw R, the arm N
and point of the screw O can be adjusted with reference to the diaphragm, and
simultaneously the armature M is set nearer to, or further from the pole of
the magnet.
When no current is passing through the coils, the effect of the spring Q is to move
the armature away from the pole, but when the current is established, and the electro
magnet so energized the attraction of the magnet balances the pull of the spring and
the armature is thus held in magnetic equilibrium. When this occurs, the armature
stands close to the pole, without touching and the point of the screw O is in light
contact with the center of the diaphragm.
Now when speech is uttered in front of the mouth-piece, the sound wave on its
inward swing moves the diaphragm inwardly, this in turn acting upon the screw O
moves inwardly the arm N and hence the armature M is carried away from the pole of
the electro magnet. When the sound wave starts on its outward swing the diaphragm
tends to leave the point of the screw O and the arm is free to move outwardly as the
armature is drawn downward by the attraction of the magnet.
So that if, for example, a wave of rarefaction moves the armature away from the
pole, the immediately recurring condensation will leave the armature wholly controlled
by the magnet.
The armature M is of course polarized by contact with the pole I to which it is
pivoted and it is thus rendered more sensitive to the attraction of the magnet.
In order to prevent the arm N from being thrown too far from the diaphragm, a fixed
stop or limiter S is provided.
In the modification of the instrument as shown in Fig. 4, 0¹ is an adjustable stop
or limiter supported by the diaphragm at its center, passing through the same and
making contact with the arm N. S₁ is a bracket supported on the rear side of the
diaphragm and carrying an adjustable screw stop S". The range of movement of the
arm N is therefore limited by the points of the stop O¹ and the stop S¹¹.
T is a metal case which is pivoted to the frame arm C at U and which may be
turned back as indicated by dotted lines, Fig. 1 to expose the interior mechanism.
It will be evident from the foregoing that the armature is under the control of the
diaphragm during but one phase of the vibration of the latter. That is to say, the
energy of the sound waves produced by the voice acts only to carry the armature away
from the pole of the magnet, and moves it against the magnetic attraction. During
the second or return phase the diaphragm moving away from the armature no longer
controls it. Hence the armature is brought back to its original position solely by the
energy of the magnet which energy is derived from the normal current, and
consequently to the extent that energy is so expended the current is then weakened.

page_text: Such being the fact it follows that the resulting current which traverses the conductor
does not copy the movement of the air particle set in motion by the voice during both
phases of its to and fro vibration but only during one phase, namely, that one during
which its movement is controlled by the sound wave and not during the phase when
its return is effected simply by the attractive energy of the magnet. The vibrations
of the current do not therefore gradually increase and diminish, and hence are not
undulatory in form. On the contrary, they diminish in intensity suddenly at each
return phase, and so are rendered pulsatory.
Having now fully described and ascertained the nature of the said invention and
in what manner the same is to be performed as communicated to me by my foreign
correspondent I declare that what I claim is :-
1. An apparatus for transmitting articulate speech electrically containing a plate
vibrated by sound waves, an electro magnet and an armature, the said parts being
combined and arranged substantially as hereinbefore set forth, so that the armature is
moved in one direction mechanically by contact therewith of the vibrating plate and
in the other direction by the attractive energy of the magnet.
2. In an apparatus for electrically transmitting speech, an electro magnet, an
armature hinged or pivoted to one pole of said magnet and extending in front of the
opposite pole, a sound receiving body and a means (such as an arm on said armature
in contact proximity to said body) for transmitting the motion from said body while
in vibration to said armature; the aforesaid elements being disposed so that the
inward movement of the said sound receiving body is transmitted to and so causes the
free end of the armature to recede from the pole of the magnet, substantially as
described.
3. In an apparatus for electrically transmitting speech, a sound receiving plate, an
electro magnet having the faces of its poles in a plane at an angle to said plate, an
armature in bell crank form pivoted to one of said poles and having an arm extending
in front of the other pole, and another arm extending substantially parallel and
in contact proximity to and receiving motion from said plate, substantially as
described.
4. In an apparatus for electrically transmitting speech a sound receiving plate, an
electro magnet having the face of its pole in a plane at an angle to said plate, an
armature having an arm extending in front of said pole and another arm extending
between said magnet and said plate, and substantially parallel to said plate, and an
adjustable contact stop extending between said plate and said armature, substantially
as described.
5. In a telephone, an apparatus for electrically transmitting speech, a sound
receiving plate, an electro magnet having the face of its pole at an angle to said plate, an
armature having an arm extending in front of said pole and another arm extending
substantially parallel to said plate and in contact proximity thereto, and an adjustable
spring tending to withdraw the armature from the pole of the magnet, substantially as
described.
6. The combination of the frame A, having a ring seat B D, sound receiving
plate E, electro magnet G, pivoted armature M, stop O, spring Q and fixed stop S,
substantially as described.
r 1887.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.