Alarm switch having resilient gripping structure for sensing unauthorized movement of a door

An alarm switch is mounted by means of a support for actuation by relative movement between the support and a member such as a door or window. Switches are carried by the support and an operating arm for the switches extends from the support and is adapted to be pulled a limited distance relative to the support for actuating the switches to complete an alarm circuit. Interengageable gripping members on the arm and the member pull the arm the limited distance relative to the support to actuate the switches when there is relative movement between the member and the support, and automatically disengage to free the member from the arm when the relative movement is greater than the limited distance. The gripping members are selectively disengageable to permit relative movement between the support and the member without actuating the alarm switch.

BACKGROUND OF THE INVENTION 
This invention relates to an alarm switch, and particularly to a burgular 
alarm switch with mounting means for actuation by relative movement 
between the mounting means and a member such as a door or window. 
SUMMARY OF THE INVENTION 
Among the several objects of this invention may be noted the provision of a 
simple, inexpensive and efficient burglar alarm switch for actuation by 
relative movement between the mounting means for the alarm switch and a 
member such as a door or window; and the provision of such a switch which 
is readily adapted to be mounted and set to detect relative movement 
between the alarm switch mounting means and a member, and quickly and 
easily deactivated for moving the member relative to the mounting means 
without signalling an alarm. 
Briefly, the alarm switch of this invention has mounting means comprising a 
support and is actuated by relative movement between the support and a 
member, especially a door or window. Switches are carried by the support 
and an operating arm for the switches extends from the support and is 
adapted to be pulled a limited distance relative thereto for actuating the 
switches to complete an alarm circuit. Interengageable gripping members on 
the arm and the member pull the arm said limited distance relative to the 
support to actuate the switches when there is relative movement between 
the member and the support, and automatically disengage to free the member 
from the arm when the relative movement is greater than said limited 
distance. The gripping members are initially disengageable to permit 
relative movement between the member and mounting means without actuating 
the alarm switch. Other objects and features will be in part apparent and 
in part pointed out hereinafter.

Corresponding reference characters indicate corresponding parts throughout 
the several views of the drawings. 
Description of the Preferred Embodiments 
Referring first to FIG. 1 of the drawings, there is indicated at 1 an alarm 
switch of this invention mounted in position above a door opening 3 in a 
wall 5. At 7 is indicated a door in the door opening 3, hinged as 
indicated at 9 with the door swinging open away from the viewer. As shown 
in FIG. 2, the switch 1 has mounting means comprising a support, generally 
designated 11, for mounting switch 1 on the trim 13 of a door frame 15 at 
the top of the door, but it is to be understood that the support 11 may be 
similarly mounted on either side of door 7. Switch 1 may also be utilized 
in conjunction with double doors with support 11 mounted between the two 
doors and activated by opening the outside door. 
Referring now to FIG. 6, support 11 is comprised of any suitable material 
(e.g., plastic) and is generally rectangular in form having sides 17, a 
bottom 19 and a top 21. Flanges designated 23 extend outwardly from 
support top 21 and have openings 24 therein to receive fasteners 25 (such 
as conventional wood screws) for securing support 11 to trim 13 of door 
frame 15. It may be desirable to make support top 21 removable from 
support sides 17 thereby providing access to the interior of support 11 
but it is to be understood that such an arrangement is not necessary for 
the proper functioning of this invention. 
Housed within support 11 is a pair of switches 27 and 29 constituting 
switching means. Although two switches are shown, it is to be understood 
that a single switch or more than two switches could be used without 
departing from the scope of this invention. An operating arm 31 for 
engaging switches 27 and 29 is slidable between the switches in slots each 
designated 33 in support sides 17. Arm 31 extends from support 11 in the 
direction toward the door and is movable forward in slots 33 a limited 
distance in that direction for simultaneously activating switches 27 and 
29 to complete an alarm circuit thereby triggering an alarm. 
There are interengageable gripping members comprising a spring clip 35 on 
the end of operating arm 31 away from the support 11 and a hook 37 
swivelly attached to a screw eye 39 adapted to be threaded into door 7. 
Spring clip 35 and hook 37 are interengageable for having the door 7 pull 
the arm 31 forward to actuate switches 27 and 29 when the door swings open 
a limited amount and are automatically disengageable to free the door from 
the arm when the door swings farther open. It is to be understood that the 
spring clip 35 may be fastened to the door and hook 37 may be on the end 
of operating arm 31. 
FIGS. 3-6 show switches 27 and 29 to be mounted side-by-side in the support 
11 with a space therebetween for operating arm 31. Switches 27 and 29 each 
have an operating member (e.g., a pushbutton) 41 and 43, respectively, 
adapted to be pushed in successively to first close and then open the 
switches. The two switches are mounted in support 11 in any suitable 
manner (e.g., machine screws securing switches 27 and 29 to support bottom 
19) with operating members 41 and 43 on the side of the switch away from 
the door. Arm 31 is slidable forward and rearward and has a crossbar 45 
thereon constituting means for simultaneously engaging operating member 41 
of switch 27 on one side of arm 31 and operating member 43 of switch 29 on 
the other side of arm 31 as door 7 is opened and the arm is pulled 
forward. 
In operation, the support 11 is mounted on door frame 15 in such a position 
that the operating arm 33 extends from the support in the direction toward 
the door with the screw eye 39 threaded into the door generally opposite 
the arm as illustrated in FIG. 3. Hook 37 is swivelly attached to screw 
eye 39 and is interengaged with spring clip 35 on the forward end of 
operating arm 31 for actuation of the alarm switch by the opening of the 
door. 
Now referring to FIG. 4, it can be seen that operating arm 31 is pulled 
forward when the door is opened causing crossbar 45 to engage with 
operating members (e.g., pushbuttons) 41 and 43. The operating members are 
simultaneously pushed forward by the crossbar and switches 27 and 29 are 
closed to complete alarm circuits thereby signalling an alarm. As the door 
is farther opened (FIG. 5), hook 37 automatically disengages from spring 
clip 35 to allow the door to be completely opened without harming the 
alarm switch. After disengagement of arm 31 and door 7, operating members 
41 and 43 automatically return to a retracted position with switches 27 
and 29 remaining closed and the alarm continuing to signal. The alarm 
signal may be stopped by manually pulling arm 31 forward causing crossbar 
45 to push operating members 41 and 43 forward to open the switches. Upon 
release of the arm, the operating members automatically return to a 
retracted position and the entire process can be repeated. 
The alarm switch of this invention is also adapted to be selectively 
deactivated in a quick and easy manner such that the opening of the door 
will not actuate the alarm switch and trigger an alarm. Spring clip 35 and 
hook 37 need only be disengaged thereby preventing door 7 from pulling 
operating arm 31 forward to close switches 27 and 29. 
Alternatively, FIG. 7 shows an alarm switch 1a similar to that previously 
described except that the switches 27a and 29a are mounted in support 11a 
spaced in a forward-to-rearward direction. Arm 31a extends alongside both 
switches and has lateral fingers 47 and 49 for engaging the operating 
members 41a and 43a respectively, as the door is pulled away from the 
support. 
Although the alarm switch of this invention has been described above as 
being used in conjunction with a door, it is to be understood that it may 
be similarly utilized for detecting the movement of any object relative to 
support 11 or 11a. 
In view of the above, it will be seen that the several objects of the 
invention are achieved and other advantageous results attained. 
As various changes could be made in the above constructions without 
departing from the scope of the invention, it is intended that all matter 
contained in the above description or shown in the accompanying drawings 
shall be interpreted as illustrative and not in a limiting sense.