Improvements in Electric Telephone Transmitters.
Year: 1898

page_text: Date of Application. 18th July, 1898-Accepted, 20th Aug., 1898
COMPLETE SPECIFICATION.
Improvements in Electric Telephone Transmitters.
I, ALFONSO MARIA MASSARI, of 163, Via Torino, Rome, in the Kingdom of Italy,
Commander of the Italian Naval Reserve, 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 electric telephone transmitters and has for its object an
efficient transmitting instrument of simple construction that can be readily
repaired when necessary and in which the transmission can be very delicately
regulated.
In order that my said invention may be clearly understood and readily carried into
effect I will proceed to fully describe the same with reference to the accompanying
drawings in which:
Figure 1 is a side elevation partly in section; and
Figure 2 is an end elevation of an instrument made according to my
invention.
A is a plate of insulating material, preferably of ebonite, having a central opening
therein and having the sleeves a and a¹ formed on or attached thereto. B is
the mouthpiece of the instrument, and is removably attached to the
insulating sleeve a preferably by means of the screws b. C is a hollow metal cylinder
which has an annular groove c on its outer periphery and has an internal recess
formed at one end thereof which fits over the insulating ring a¹ and is secured
thereto. D is a tube having its free end screw threaded, & is a plate having a central
opening therein into which one end of the tube D is fitted, and d¹ is a short hollow
cylinder attached to 'the edge of the plate d. The tube plate d and cylinder d¹
are of brass or other suitable conducting material. The tube D passes through the
plate A and cylinder C, and has its screw threaded end projecting beyond the latter.
S is a coiled spring, situated between the plate d and a shoulder formed by the afore-
said internal recess in the cylinder C, for a purpose hereinafter referred to. d2 is a
die screwed onto the free end of the tube D and d³ is a washer for securing the said
die in position.
The cylinder d¹ contains a carbon block E situated opposite the central opening in
the plate d and held in position and insulated by chalk F. f is a piece of cotton or
felt placed in a recess in the carbon block E. fl is a ring of cotton and e is granu-
lated carbon. H is the diaphragm and I is an elastic ring or tube of rubber or of
any other soft insulating material which separates and insulates the diaphragm from
the mouthpiece. a² is an insulating sleeve, preferably of ebonite which fits into
the tube D and has an annular flange at its outer end. g is a metal rod which passes
through the sleeve a² and rests upon the carbon block E, and g¹ is a nut for regulat-
ing the length of the rod g. R is a sliding piece of metal having a longitudinal
slot therein. 1 is a screw secured to the base A¹ and on which the piece R slides.
This sliding piece R has a knob or handle r² at one end thereof and has its opposite
end forked so as to slide into the groove c on the cylinder C and thus secure the
instrument to the base A¹. The ends of the fork are recessed and fit onto the
screws when in this position. One end T of the line wire is attached to
n
11

page_text: the sliding piece R, and the other end T¹ thereof is attached to a contact piece t
which bears on the metal rod g.
The electric current is thus connected through the sliding piece R, cylinder C,
and plated to the cylinder d', and through the rod g carbon block E and granulated
carbon e to the diaphragm H.
When not in use the diaphragm is supported between the cotton or felt pieces f,f
and the rubber ring I. When the instrument is in use the diaphragm vibrates, and in
so doing makes and breaks contact with the cylinder d¹. The spring S normally
tends to press the cylinder d', plate d, and tube D towards the diaphragm. The
die d² acts against the pressure of this spring and bears against the free end of the
cylinder C. The transmission is regulated by adjusting the pressure on the diaphragm,
and this is effected by means of screwing up or unscrewing the die d² and its
washer ds and thus respectively decreasing or increasing the pressure on the
diaphragm; by which means a very delicate adjustment. can be effected.
In telephone transmitters of the type in which granulated carbon is used as
described, it sometimes happens that from a sudden shock or other cause the
granulated carbon becomes displaced and a part of it finds its way between the
cotton wool and diaphragm to the cylinder d¹ thus making contact and rendering
the transmitter useless. Should this happen in the case of an instrument made
according to iny invention, the latter may be quickly and easily repaired by means
of removing the screws b, when the mouthpiece B and diaphragm H can also be
removed, the granulated carbon replaced, and these parts readjusted.
By means of attaching the mouthpiece to the insulating ring a and also insulating
it from the diaphragm by means of the rubber or like ring or tube I it is possible to
use a metal mouthpiece.
By means of drawing back the sliding piece R into the position shown in dotted
line in Figure 2 contact between the terminal wire T and the cylinder C is broken
and the instrument can then also be withdrawn from the base A¹.
0
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 telephone transmitter of the type herein referred to, means for
regulating the diaphragm thercof consisting in a spring which causes pressure to be
exerted or the back of the diaphragm, and means for regulating the tension of said
spring, substantially as described and for the purpose specified..
2. An electric telephone transmitter having the mouthpiece thereof removably
attached thereto and insulated therefrom, substantially as described and for the
purpose specified.
3. Means for connecting a telephone transmitter to its base consisting of a forked
sliding piece which carries one of the terminal wires and the fork of which takes
into a groove on the stem of the instrument, substantially as described.
4. An electric telephone transmitter having its parts arranged and operating
substantially as herein described and set forth in the accompanying drawings.
11
LOLL
1000
Dated this
day of July 1988.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.