Improvements in or relating to Electric Bells or Signals.
Year: 1896

page_text: Date of Application, 27th July, 1896
Complete Specification Left, 27th Apr., 1897-Accepted, 19th June, 1897
PROVISIONAL SPECIFICATION.
Improvements in or relating to Electric Bells or Signals.
JOHN RENDELL 16 Long Street Devizes Wilts Whitesmith do hereby declare the
nature of this invention to be as follows:-
This invention relates to certain improvements in or relating to electric bell door
triggers, burglar alarms &c., and the object of my invention is to make them inore
certain in action than those at present in use. I make a trigger with a loose or hinged
rocker, having projecting lugs to rest on frame or support, the said lugs when in use
making contact with a metal spring, in position to ensure good rubbing contact.
I make a burglar alarm with a rocker movement similar to the above, or with a
hinged lever or spring, with projections to make contact with another spring fixed at
right angles.
Improvements in or relating to Electric Bells or Signals.
I, JOHN RENDELL of 16 Long Street, Devizes, in the County of Wilts, Whitesmith,
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 relates to improvements in the construction of electric contact
devices controlled by the opening and shutting of doors, windows and the like, for
use in connection with electric bells or signals especially such as are commonly
known as burglar alarms.
The accompanying drawings show two forms of a contact device constructed in
accordance with this invention.
Figures 1 and 2 are perspective views,
Figure 3 a plan, and
Figure 4 a section on the line 4-4 of Figure 3 of a door trigger.
Figure 5 is a perspective view and
Figure 6 a side elevation of a contact device specially applicable in connection with
burglar alarms.
Like letters indicate like parts throughout the drawings.
Referring to Figures 1, 2, 3 and 4, A is a plate for affixing the device, say to
the frame of a door, as shown in Figs. 1 and 2. The bed plate A carries a bracket B
with parallel sides B1 B³, provided with upwardly extending semi-circular ears B.
C is a Y shaped rocker comprising a single leg, extending a convenient length
below the bracket, and two curved arms CC placed between the sides B B of
the bracket B. These arms have lugs C, which bear on the top edge of the bracket
sides, at the points where the semi-circular ears B' commence to rise. A slot or

page_text: hole is formed in the centre of the upper edge of each arm of the rocker C, to receive
a rod or pin C, furnished with a spiral spring (5, the onds of which are fastened
to the bracket ears B³. One of the lugs of the rocker arm C is extended outwards
and downwards forming an arm C which acts as the contact maker. D is a flat
spring fastened by the screws, D', to the insulating block E, and with its free end
resting on the insulating peg E'. The block E and peg E' may be made of
vulcanite or any suitable non-conducting material, and are affixed on the outside
of B¹.
The device operates as follows:-When at rest, as when the door is shut or open
sufficiently wide to clear the device as shown in Fig. 1, the four lugs (3 of the
rocker arms bear on the top of the bracket sides B B2, whilst the contact arın C
does not touch the flat spring D. The rocker leg langs vertically below the bracket,
so as to engage with the top of the opening door, which forces it into the position
shown in Fig. 2, the rocker arm C² being raised, and drawing the contact arm (6
across the free end of the spring D, thus making electric connection between the
spring D and the bracket frame and operating the bell or alarm. When the door
has cleared the device the rocker is returned to the position of rest by the tension
of the spiral spring C, and contact is broken. Whilst the door is being shut the
rocker leg is again engaged and the rocker raised but in the reverse direction, the
arm keeping its bearing on the top of the bracket sides whilst the rocker arm
is raised, as shown in dotted lines in Figure 4. On the closing of the door, the
rocker leg is disengaged and the rocker again returned to the position of rest.
As shown in the drawings the spring D is arranged to make contact with the
arm C at its free end only, when the arm is raised by the opening of the door, but
it is evident that by setting in the spring as soon as clear of the insulating block E
or by lessening the thickness of the block and giving no set in to the spring, contact
would be made in both motions of the rocker, and warning given both of the opening
and shutting of the door.
Instead of the rod C bearing on the rocker arins and the ends of the spiral
spring C being fastened to the bracket cars B³, the arrangement may be reversed,
the rod being placed through holes in the cars and the spring ends fastened to or
bearing on the rocker arms. Or the rocker may be weighted so as to tend to maintain
always its mean or central position.
Referring to Figures 5 and 6, A is a flat plate for affixing the burglar-alarm, say to
the sash frame of a window and is provided with ears or lugs A and a slot A
A flat bar F is connected by a hinge joint to the plate A. As shown in the drawings
this joint is formed by passing a pin G through holes in the lugs A' and through
corresponding holes in turned down lugs provided on the bar F but any convenient
form of hinge may be used. The body of the bar is normally parallel with the
plate A its free end is turned down so as to rest on the plate over the slot A², and
is provided with a curved knob F¹ projecting through the slot. The turned down
end is held against the plate by the tension of a spring or other equivalent control
device which may be applied in any convenient manner, preferably in the form of a
spiral spring G placed on the pin G as shown in Fig. 5. The bar is provided near
its free end and preferably at the commencement of the bend with a lug F, placed
at right angles to it in the direction of the frame A. This lug forms the contact
maker with the flat spring D which is placed between the bar F and the place A,
being fastened by screws D₁ to the insulating block E fixed on the frame A. The
hinged end of the bar may be turned down, as shown at F3 to form a stop.
As long as pressure is applied to the knob F', as for instance by the sash of a
window when shut, to hold the arm F in the position shown in Figure 5, the contact
maker F2 is held above and out of contact with the flat spring D. On the pressure
being removed from the knob F¹, as for instance by the raising of the window sash,
the tension of the spring G forces the bar F down, until its end rests on the plate A,
as shown in Fig. 6, the contact maker F being thereby drawn across the free end
of the spring D and placed in contact with it, thus forming an electrical contact
between the spring D and the plate A, and operating the bell or alarmı.

page_text: In both devices means are provided in the usual way for connection with the
battery and alarm, such as the screws D' on the spring and A' on the frame.
In both the devices herein described contact is made by drawing or rubbing the
contact maker across a spring, arranged to yield in a direction at right angles to
the plane of the path of the contact maker. By this arrangement a good electrical
contact is ensured with but a slight deflection of the spring as the action tends to
remove any foreign matter, such as dust or the products of oxidation, which may be
accidentally placed or formed on the contact surfaces.
Although the devices according to this invention are hereinbefore described as
applied to a door and window respectively it must be understood that I do not confine
myself to that particular application of either device, nor do I confine myself to the
details of form and construction described herein.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:-
1. In a door-controlled electric contact-device, or the like, a rocker such as C
constructed to oscillate in two paths, and to make rubbing contact in both for the
purpose described.
2. In a door-controlled electric contact-device, or the like, a rocker such as C
constructed to oscillate in two paths and to make rubbing contact in one path but not
in the other for the purpose described.
3. In a door-controlled electric contact-device, or the like, the combination of a
support such as B, rocker such as C, means to keep the rocker in position and a
contact spring to rub the rocker, substantially as and for the purpose described.
4. In a door-controlled electric contact-device, or the like, the employment of a
contact spring arranged to yield in a direction at right angles to the plane of the path
of the moving contact which rubs against it.
5. In a door-controlled electric contact-device, or the like, the combination with a
bar such as F of a contact spring to rub against it substantially as and for the purpose
described and illustrated in Figures 5 and 6 of the accompanying drawings.
6. The combination and arrangement of parts constituting the complete door or
the like controlled electric contact-device substantially as and for the purpose described
and illustrated in Figures 1, 2, 3 and 4, or in Figures 5 and 6 of the accompanying
drawings.
Dated this 27th day of April 1897.
BOULT & WADE,
Agents for the Applicant.