Burglar alarm for door knob

A burglar alarm apparatus is provided with a housing adapted to slide over a door knob for actuation upon rotation or attempted rotation of the door knob. An insert is provided for insertion into the housing which has a protruding suction cup so that the door knob burglar alarm can be converted for use on windows or sliding glass doors or the like. The burglar alarm has a sensor switch of the platform and ball type, which is resettable and may be turned off by a single switch knob.

BACKGROUND OF THE INVENTION 
The present invention relates generally to alarm devices and is more 
specifically directed to devices that can be temporarily placed on 
conventional door knobs to act as burglar alarms, but which can be 
converted to an alarm for a window or sliding glass door, or the like. 
Alarm devices for attachment to door knobs for sounding alarms when anyone 
attempts to enter a door have been suggested in a variety of forms. 
Typically, these alarms slide over and engage a door knob in a 
sufficiently secure manner and has to be rotated when the door knob is 
rotated, thereby actuating a switch such as a mercury switch, located in 
the burglar alarm housing. Other such alarms may be held to the door knob 
with a latching or spring-loaded device, or may be bolted to the door knob 
for actuating a separate alarm. Typical prior art door knob alarms may be 
seen in U.S. Pat. No. 3,488,651, to Brenner, for a portable alarm which 
has a bracket which clips over a door knob, and includes a mercury switch, 
which is actuated by the rotation of the alarm housing. The U.S. Pat. No. 
3,725,892, to Faltico, teaches a door knob burglar alarm using mercury 
switches which has a receptacle in the housing for slipping over the door 
knob, while the Birrenkott U.S. Pat. No. 3,327,300, provides a door knob 
burglar alarm for suspension from a door knob which is actuated by an 
off-center, over balance, when the door knob is turned in either 
direction. A patent to Fontaine, U.S. Pat. No. 3,623,063, has an alarm 
which is attached to a door and has a handle which extends up over the 
door knob and is actuated by a change in the frequency of an oscillator by 
the rotation of the door knob, while the Seely U.S. Pat. No. 2,791,763, 
suspends a burglar alarm to a door knob with a switch which incorporates 
the knob so that rotating the knob shifts the housing and a support for 
the housing to complete a circuit through the door knob. The Kreuger U.S. 
Pat. No. 2,640,894, teaches a burglar alarm suspended from a door knob 
which includes an extension for a close-by window. Other door knob burglar 
alarms include the Miller U.S. Pat. No. 2,423,610, which includes an 
extension connection for attaching a suction cup to a nearby window pane 
or door, and the Fruehauf U.S. Pat. No. 704,247, having an extension 
attached to the door knob for actuating an alarm circuit, and the Getto 
U.S. Pat. No. 775,723, for an electric burglar alarm, and the Hausser U.S. 
Pat. No. 1,534,589, for an electric door knob alarm. 
In contrast with these prior door knob burglar alarms, the present 
invention provides for a door knob alarm which is easily connected to a 
door and which may be quickly removed and carried along when staying in 
motels, hotels, and other accomodations when away from home, and which may 
be quickly converted for use as a window or sliding glass door alarm; and 
which has a simplified alarm sensor which may be quickly reset or disabled 
through a single cam-actuated switch. 
SUMMARY OF THE INVENTION 
A door knob burglar alarm apparatus has a housing with a receptacle formed 
therein sized to fit over a door knob, which receptacle is partially lined 
with a resilient material for frictionally engaging the door knob so as to 
move the housing upon the rotation of the door knob. The alarm housing has 
an electrical circuit disposed therein which includes batteries connected 
to an annunciator through a sensor switch which senses the movement of the 
housing to actuate the annunciator. The sensor switch has a conductive 
ball switching member, located on a conductive platform adjacent a 
conductive wall, so that movement of the housing will cause the ball to 
roll off the platform between the conductive platform and the conductive 
wall to complete a circuit from the battery to the annunciator for 
actuating the annunciator. The sensor switch is reset by a "reset and off" 
knob which rotates a cam to slide a reset platform located around the 
platform against the ball so that the ball can roll back upon the 
platform. The reset platform can be locked up to prevent contact between 
the ball and the conductor walls through the ball. An insert attachment 
may be shaped like a door knob and may be insertably mounted into the 
housing receptacle in place of the door knob, and has a suction cup 
fixedly attached thereto so that the burglar alarm can be attached with a 
suction cup to a window or sliding glass door to sound an alarm upon the 
opening or jarring of the window or sliding glass door.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, FIG. 1 illustrates a door 10 through an 
exterior or interior wall 11 of a building and having a door knob 12 with 
a burglar alarm 13 attached thereto which burglar alarm has a switch knob 
14 and a housing 15 which housing has a grille opening 16 therein. As more 
clearly seen in FIG. 2 and 3, the housing 15 has an electrical annunciator 
17 which sounds an alarm through the grille 16. The annunciator 17 is 
connected by a pair of conductor wires 18 to a conductor wall 20 which may 
be a hollow, cylindrical metal or a metal coated polymer wall. The 
annunciator is also connected by a wire conductor 22 to a battery contact 
23 which, in turn, makes contact with a battery 24, while the opposite 
pole of the battery makes contact with a battery contact 25 which is 
connected to an electrical conductor wire 26 which is connected to a 
support platform 27 supported on a base portion 30 of the battery 
compartment. A conducting metal sphere 31 normally rides on the conducting 
metal coated top 32 of the platform 27 until the housing 15 is rotated or 
jarred, at which time the metal ball 31 can roll off of the top 32 and 
lodge between the sides of a conducting portion of the platform 27 and the 
conducting portion of cylindrical wall 20, thereby making contact 
therebetween and completing the circuit from the annunciator 17 through 
the conducting wires 18 and the conducting wall 20 through the sphere 31 
and through the conducting platform 27 thereby through the conducting wire 
26 to the battery contact 25 to complete the circuit and actuate the 
annunciator 17. It will, of course, be clear the wall 20 and platform 27 
can be either made of a solid metal material or can have portions coated 
with an electrical conductive material without departing from the spirit 
and scope of the invention. Once the alarm has been actuated, it can be 
reset by the rotation of a pair of cams 33 mounted to a shaft 34 which, in 
turn, is connected to a rotating reset knob 35 located on the exterior of 
the housing 15. Rotation of the knob 35 rotates the shaft 34 and the cams 
33 located in the hollow portion 36 of a resetting sleeve 21 to drive the 
sleeve 21 upward to a position that the sphere 31 can roll back on top of 
the top 32 of platform 27. When the switch knob 35 is rotated in the 
opposite direction, the resetting sleeve 21 is lowered by the cam 33. The 
switch knob 35 can be rotated to lock the cams 33 either up to disable the 
alarm or down when the alarm is set. 
Thus, when the cams 33 are locked in their up position with the reset 
sleeve 21 up, the sphere 31 cannot make contact between support 27 and 
wall 20, thereby turning the alarm off and preventing the closing of the 
circuit when the alarm is being stored or transported. Platform 27 has a 
passageway therethrough for shaft 34, and sleeve 21 has openings 36 
therein as well as angled ledge 37, which assists the sphere 31 in rolling 
onto the top 32. 
A receptacle 40 is partially lined with a resilient plastic foam, or foam 
rubber 41, and is shaped to engage an average door knob frictionally, with 
the foam 31 to support the burglar alarm housing 15 on the door knob. 
However, under certain circumstances, the alarm owner might wish to use 
the alarm on windows or sliding glass doors in which event, an attachment 
insert 42 shaped like a standard door knob, to fit the receptacle 40 of 
the housing 15, which may be of a rigid foam plastic, such as a foamed 
polystyrene may be inserted in a receptacle 40 of the housing 15. The 
knob-shaped attachment 42 has a protruding portion 43 with a suction cup 
44 fixedly mounted thereto, so that upon the insertion of the ball 42 into 
a receptacle 40, the entire housing may be attached to a window, sliding 
glass door, or any other surface with the suction cup 44 to act as an 
alarm for the window or the sliding glass door, or the like. 
The present alarm advantageously may be disconnected with the switch 35 and 
packed in a bag, or the like, with the attachment 42, and taken on trips 
for use in motels or the like, on either windows or doors. A simple 
central switch actuates the alarm whether it is rotated or jolted, or 
moved in a lateral direction, thereby allowing the alarm to be used on 
different entryways. It should be clear at this point that a burglar alarm 
for doorknobs, windows, and the like, has been provided which provides for 
different types of attachments, but it should also be clear that other 
variations are contemplated as being within the spirit and scope of the 
invention, which is not to be construed as limited to the particular forms 
disclosed herein.