Improvements in Combined Telephonic Jacks and Call Indicators.
Year: 1899

page_text: COMPLETE SPECIFICATION.
Improvements in Combined Telephonic Jacks and Call Indicators.
We, SIEMENS BROTHERS AND CO. LIMITED, of 12, Queen Anne's Gate, West-
minster, S.W., Electrical Engineers, do hereby declare the nature of this invention
(as communicated to us from abroad by Siemens & Halske, Actien Gesellschaft,
of Markgrafen Strasse 94, Berlin, S.W., Electrical Engineers) and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement:—
This invention relates to improved constructions of combined jacks and call
indicators for telephone exchange switchboards.
As is known, a telephonic call jack consists of the combination of a call, that
is to say an indicator drop or other visible or audible indicating device, and a
jack and stopper for establishing the communications.
According to the present invention the call is effected by causing an electro-
magnet to actuate an axially arranged indicator which is caused to be protruded
by spring power.
By this arrangement the device is made to occupy only very little room, and
all the parts are arranged centrally one behind the other.
A farther advantage consists in that the appliance can be arranged in any
position, both vertically and horizontally, so that it is of considerable value in
particular with horizontal switchboards, where the provision of indicator drops
on the table is inconvenient on account of their necessary horizontal position.
The invention can be carried out in various ways, we will describe, by way
of example, two modifications in connection with the accompanying drawings.
In the arrangement shewn in longitudinal section at Fig. 1 the indicator device
consists of a coloured cap & situated within the jack casing 6, and urged upward
by a spring within the same, the cap being held in the withdrawn position
by the catch h which is protected from dust.
Below the cap, in the same axial line therewith, is a solenoid which, on the
passage of a call current acts magnetically on the fixed iron core and on the
moveable one. In the fixed core is_contained a light sliding rod B against
which on the passage of a current, the moveable core strikes, causing the
rod to actuate the catch h so as to liberate the cap, whereupon the spring f
pushes the latter upward.
If the operator now inserts the stopper shewn over the call jack, the cap will
be pressed down again, causing the angular locking piece at the lower end of
the cap stem to engage with the catch again.
The contact springs for effecting the required telephonic connections can be
arranged in any required manner between the cap and the casing.
It will be evident that the cap k might be arranged to fit partly or wholly over
the outside of the jack casing 6, so as to be guided thereby.
The arrangement shewn at Figs. 2 and 3 is of a somewhat simpler construction.
In this case the mechanical locking of the cap stem is replaced by a magnetio

page_text: locking device; a permanent magnet B arranged within a tube A, has coils C
provided on its limbs.
D is an armature of soft iron which when in the position of rest, as at Fig. 2,
is held by the poles of the magnet B. To this armature is attached the indicator E
which is to be made visible by means of a stem F, sliding in a guide. The
spring G acting upon the stem and indicator is under compression when at rest.
His the stopper: on the insertion of this into the jack casing it depresses the
indicator again and makes the necessary connections.
The action is as follows:-
The indicator having been depressed and the stopper H removed, the armature D
remains attracted by the poles of the magnet B, the spring G, being compressed.
If a current be now passed through the coils C, the magnetism of B is altered,
the coils C being so wound as to weaken the magnet.
The compressed spring G can now draw the armature away from the magnet
and thereby raises the indicator E into the visible position at Fig. 3. The
stopper being then inserted, the indicator is again depressed and the necessary
connections are made between the usual contact springs of the jack and the leads
of the stopper.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:---
1. A combined telephonic call indicator and jack wherein the indicator con-
tained within the jack casing is acted upon by a spring for bringing it into the
protruded position and is held in the withdrawn position by a catch which is
released by a disengaging device on the transmission of a call current, the
indicator being moved back into its withdrawn position by the insertion of the
stopper into the jack for making the required telephonic connections, substantially
as described.
2. In a combined telephonic call indicator and jack such as is referred to in
the first claim, the arrangement whereby the indicator is held in the withdrawn
position by means of a permanent magnet whose armature is connected to the
indicator the strength of the magnet being decreased on sending a call current
through coils thereon, so that the indicator can then be protruded by means of
a spring, substantially as described.
Dated this 24th day of March 1899.