Improvements in Telephones.
Year: 1894

page_text: Date of Application, 9th Nov., 1>94
Complete Specification Left, 8th Aug., 1895-Accepted, 14th Sept.,
1895
I, EDGAR CHARLES PARKER of 66 Glyn Road, Homerton, in the County of
London, Electrical Engineer do hereby declare the nature of this invention to be
as follows:-
In those telephones in which granulated carbon is employed the carbon granules
are liable to become packed or compacted, chiefly by reason of the vibrations of
the diaphragm and the result is that the vibrations cease to act upon them to the
same extent and the efficiency of the instrument is thereby impaired. One object
of my invention is to obviate this packing of the granules and for this purpose
I place them in a holder which is capable of being turned or moved by means of a
button or other suitable device so as to reverse or alter the relative positions of
the granules. Thus by turning or moving the holder from time to time or
whenever the tendency to pack becomes apparent the granules are at once loosened
from each other. The preferable form of the holder is polygonal.
Another object of my invention is to ensure the necessary contact of the spring
switch for ringing or speaking when the receiver is attached to the front of the
instrument. For this purpose I fix to the back of the receiver a tongue-like piece
of metal inclined at a suitable angle and I form an opening in the front of the
instrument to receive the said tongue-like piece. When the tongue-like piece is
introduced into the said opening and pushed or moved downwards it comes against
the spring switch and, owing to the inclination of the tongue, gradually forces it
against the part with which it has to make contact.
Dated this 9th day of November 1894.
J. C. MEWBURN & ELLIS,
55 and 56 Chancery Lane, London, Patent Agents.
Improvements in Telephones.
I, EDGAR CHARLES PARKER, of 66 Glyn Road, Homerton, in the County of
London, Electrical Engineer, 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 improvements in telephones.
"
or
It has been found that in those telephone transmitters in which granulated
carbon is employed there is a tendency for the carbon granules to "pack
settle down close together after the telephone has been in use for some time.
This packing is chiefly caused by the vibrations of the diaphragm of the
transmitter. In consequence of such packing the vibrations cease to act on the
carbon granules to the same extent as they did before the packing and con-
sequently the loud speaking capabilities of the telephone are seriously impaired.
When such a condition of the carbon is arrived at it has hitherto been usual to
take down the telephone and shake it in order to loosen the carbon granules and
thus restore the loud speaking qualities of the telephone.

page_text: One part of my invention relates to the provision of simple means for restoring
the loose condition of the carbon whenever required without necessitating the
removal of the instrument from its position. For this purpose I enclose the
carbon in a holder which is capable of being rotated by means of a button or
the like so as to loosen and alter the relative position of the granules when
required. By turning the holder from time to time, or whenever the tendency of
the carbon to pack becomes apparent the granules are at once loosened.
Another part of my invention relates to a reliable method of making the
necessary contacts in the ringing circuit, when the receiver is "hung up," so that
on the bell circuit being completed at the distant station the call bell at the near
station is operated.
In order that my invention may be clearly understood I will now more fully
describe the same with reference to the accompanying drawings, in which,
Figure 1 is a front elevation of a telephone transmitter constructed according to
my invention, the front plate being removed.
Figure 2 is a rear elevation thereof.
Figure 3 is a vertical central section of the transmitter and of the case of the
receiver showing the latter "hung up" on the front plate of the transmitter.
Figure 4 is a view of the front plate detached.
Figures 5 and 6 are detail views of the carbon holder to be hereinafter
described.
Like letters denote corresponding parts throughout the drawings.
A is the transmitter, B is the case of the receiver; C is a vibrating diaphragm
which is preferably constructed of mica. On the diaphragm C is mounted a
rotatable carbon holder which consists preferably of a polygonal tube of metal
constructed in two halves D and D2 (shown separated in Figure 6) that are
mechanically connected by some suitable insulating material such as gold-beater's
skin E Figure 5. The skin E is wrapped round the two parts D1 and D2 to form
a complete tube but at the same time leaving a short space between the inner ends
of the two parts D' D². The tube or holder after being nearly filled with carbon
is mounted in bearings F F attached to the back of the mica diaphragm and is
rotatable in the bearings just out of contact with the diaphragm. The spindle D
of the holder extends through the side of the transmitter case and is furnished
with a button G by which the holder can be rotated. The two parts D1 and D2 of
the carbon holder constitute the two electrodes of the transinitter A and are
connected by metal strips H H to the contact screws of the instrument.
When the action of the insrument becomes impaired by reason of the packing
of the carbon all that need be done to loosen the same is to give a turn or two to
the holder by means of the button G. This will shake up and loosen the granules
and render the operation of the telephone as perfect as before.
I find it advantageous to employ carbon fibres instead of granules in the holder
as they have less tendency to pack together.
The bell circuit of my improved telephone has two breaks in it, one at the near
station and one at the distant station. When the receiver is hang up on the front
plate I of the transmitter one of these breaks is automatically bridged over and the
operator at the other end can then ring the bell by pushing his bell contact.
when the receiver is not hung up on the plate I the operator at the other end
cannot ring the bell at the near station.
"
But
In carrying out this part of my invention I provide the back of the receiver B
with an inclined hook or tongue B¹ by means of which when the receiver is "hung
up' the bell contact spring or switch J is pressed against the contact pin K
(Figure 3) thereby bridging the break in the bell circuit at the near station. The
peculiar shape of the hook B' in combination with the bevelled bottom edge I'
(Figure 3) of the opening 1' in the plate I ensures that the spring switch J shall
make proper contact with the pin K by the mere gravity action due to the weight
of the receiver B.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what [
claim is :-
1. A telephone transmitter, provided with a rotatable holder for the carbon for
the purpose specified.
2. The rotatable carbon-holder constructed of two parts connected by insulating
material and mounted in bearings carried by the diaphragm, substantially as
described.
3. In a telephone transmitter the means substantially as described by which the
receiver, when hung on the front plate of the transmitter, causes a contact to be
made in the bell-circuit so that the bell can be rung from the distant station.
4. A telephone transmitter constructed substantially as described with reference
to the accompanying drawings.
Dated this 8th day of August 1895.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.