Improvements in Electric Burglar Alarms.
Year: 1891

page_text: te of Application, 27th Nov., 1891-Accepted, 2nd Jan., 1892
COMPLETE SPECIFICATION.
Improvements in Electric Burglar Alarms.
I, FRANZ POHL, Junior, Merchant of Tetschen on the Elbe, Bohemia 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 improved apparatus intended to be used in
connection with roller blinds or shutters or all kinds and with window sashes and
doors and in general with matters or things by the removal or displacement of
which unauthorized persons may enter or obtain access to places which they are not
intended to enter or obtain access to. The improved apparatus is intended to cause
an electric current to sound an alarm when such shutters, window sashes, doors etc.
are so moved.
The drawing illustrates the invention
Fig. 1 being a sectional view of the improved attachment.
Fig. 2' a plan view thercof.
Fig. 3 a sectional view of a modified form.
Fig. 4 a plan view of part thereof.
Fig. 5 illustrates the apparatus as applied to a roller shutter.
A is a tube of metal, glass, or any suitable material which may have the metal
cap B. This tube is built into or suitably fixed in or on the masonry or fixed
construction of the house, room or place near the roller shutter C or other object
as aforesaid. The lower end of the tube A issues in a cavity or closed receptacle D
in which are the two insulated contact blocks E E severally connected by wires to
the battery F and electric bell or other alarm G.
Through the tube A passes the thread H fastened at the upper end to the hook J
which is intended to be hooked into an eye on the roller shutter or the like when
closed; at the lower end of the thread H is suspended a metallic or electrically
conductive plate or contact piece K.. When the hook is fastened in the eye
aforesaid the said contact piece is suspended above the contact blocks E E, should
the shutter be raised without unfastening the hook J, the hook will pull the
thread H until the picce K is stopped by the end of the pipe A. A further pull
on the thread will break the latter and the contact piece K will fall onto the
plates EE and connect these plates electrically so that the circuit is closed and the
alarm is sounded.
In Figs. 3 and 4 the contact blocks are made in the form of sections of a hollow
inverted cone as E' E' while the contact piece is made in the form of a sphere
as K
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 ;-
In an electrical alarm apparatus to be attached to any closing device, a thread
connected by hook or otherwise to said device, the said thread extending through
a tube A and carrying a contact making plate or body adapted on the breaking of
the thread in the manner described to fall upon or between contact blocks and thus
close the electric circuit including the alarm.
Dated this 14th day of November 1891.
HERBERT & Co.,
18, Buckingham Street, Strand, London, W.C., Agents to Applicant.