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Publication numberUS2236689 A
Publication typeGrant
Publication dateApr 1, 1941
Filing dateMay 26, 1938
Priority dateMay 26, 1938
Publication numberUS 2236689 A, US 2236689A, US-A-2236689, US2236689 A, US2236689A
InventorsHenri Lemire, Joseph Lemire, Rodolphe Lemire
Original AssigneeNorbert Boisvert
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Control device for electric alarms
US 2236689 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Apri 1941. J. LEMIRE TAL 2,236,689

CONTROL DEVICE FOR ELECTRIC ALARMS Filed May 26, 1938 JOSEPH LEN/EE, HENB/LErv/RE 4I/V0 Foo oz. PHE LEM/EE Patented Apr. 1, 1941 CONTROL DEVICE FOR ELECTRIC ALARMS Joseph Lemire, Henri Lemire, and Rodolphe Lemire, Drummondville, Quebec, Canada, assignors of one-half to Norbert Boisvert, Drummondville, Quebec, Canada applicati@ May ze, 193s, serial No. 210,218

1 Claim.

The present invention pertains to a novel device for controlling and governing the operation of an electric alarm.

The principal object of the invention is to provide such a device adapted to be mounted on a structural member that Vibrates when a forcible entry is attempted. Such a member may be, for example, a window sash, window or door, or the frame or surrounding structure associated with a window or door. invention embodies a pair of contacts carried by the vibratory member and governing the circuit to the alarm. One of these contacts is adapted to vibrate relatively to the other when the structural member vibrates. The vibratory Contact is made relatively movable by suitable means such as a vibratory support, a weight or both. Where a resilient support is used, the invention also employs means for adjusting the tension of the support.

In one form of the invention, the control device is enclosed in a casing carried by the vibratory member and carrying one of the contacts. The other contact is carried on a spring arm attached to but insulated from the casing. The arm is also weighted to introduce a difference of inertia between the contacts, so that movement of the structural member introduces relative Vibration between the contacts, with the result that the alarm circuit is rapidly made and broken.

Ordinarily, the contacts are normally in engagement with each other, and the alarm so constructed that it is idle in this condition but operates when the contacts separate. Obviously,

these conditions may be reversed, but in either case the alarm operates when one of the contacts vibrates relatively to the other.

The invention is fully disclosed by way of example in the following description and in the accompanying drawing, in which Figure 1 is a horizontal section, partly in elevation, of the device as applied to solid window frames or walls;

Figure 2 is a vertical elevation thereof;

Figure 3 is a vertical section of a window sash,

i showing in elevation a modied form of the invention applied thereto;

Figure 4 is a section on the line 4-5 of Figure 3;

Figure 5 is an elevation of the upper end of the device shown in Figure 3, and

Figure 6 is a detail, partly in section, of the lower end.

Reference to these views will now be made by In general, the device of the use of like characters that are employed to designate corresponding parts throughout.

In Figure l, the numeral l designates a structural member which may be a portion of a wall or window frame. In any case, it is a member that is likely to be subjected to vibration if a forcible entry is attempted.

The device includes a suitable bracket 2, conductive of an electric current, to which is secured one end of a Very light piece of sheet metal 3. The free end oi the member 3 is secured to the center of a weight 4 as shown more clearly at the numeral 5 in Figure 2. The assembly is enclosed in a suitable casing 6 which is also conductive of electricity. The adjacent face of the weight 4 carries a contact I normally engaging a pointed contact B on the inner wall of the casing.

'Ihe bracket 2 is insulated from the casing 6 by an insulating insert 9. This member and the metal piece 3 are secured to the bracket 2 by rivets IU. The same rivets hold one end of a soft metal sheet II adapted to engage the member I. By adjusting the bend of this sheet, the displacement of the weight 4 can be regulated.

A conductor I2 is connected to the bracket 2 by a screw I3. Similarly, another conductor I4 is fastened to the casing 6 by a screw I5. Both screws extend into the member I and may serve to support other parts of the assembly as clearly illustrated in Figure 1.

A circuit is thus ma-de through the contacts I and 8 to an alarm. The contacts are normally in engagement with each other, and the alarm is one that is inoperative when these contacts are in engagement.

When a forcible entry is attempted at or near the member I, the latter will be caused to vibrate. The weight 4 will also be set in vibration but at a slower rate because of its inertia. Consequently a separation, or repeated separations, of the contacts I and 8, will occur, opening the circuit and operating the alarm.

The modification shown in Figures 3, 4, 5 and 6 is designed for application to a movable window frame or sash. The frame member 2! carries a screw 2l which, in turn, preferably carries a bushing 22. Wire conductors 23 and 24 are suspended from the screw, the member 23 carries a weight 25 at its lower end, while the member 24 has its lower end bent and pointed at 26 and engaging in a socket 2T formed in the adjacent face of the weight 25. The upper ends of members 23 and 24 are wound around an insulating sleeve 28 tted on the bushing 22, as shown more clearly in Figure 4. Plates 29 and 30 are mounted on the sleeve 28 in engagement with the conductors 23 and 24 respectively and are held apart by an insulating disc 3l. coiled end of conductor 23, and suitable washers 33 are mounted on the bushing 22 to take up the slack.

Conductors 33 and 35 are fastened to the plates 29 and 3l) respectively, whereby a circuit is made through the lower ends of the members 25 and 26. When an attempt is made to force the Window open, the vibration separates the contacts 25 and 25 and thereby causes the alarm to operate.

Bent plate 40 placed close to window frame 20 permits to regulate the contacts by turning screw 2l. Plate Il@ engaging frame 20 at a point offset of the screw 2l causes the tilting of contacts 23 and 2li towards the glass forming part of member 2).

Although specific embodiments of the inven- A similar disc 32 engages the tion have been illustrated and described, it will be understood that various alterations in the details of construction ,may be made without departing from the scope of the invention, as indicated by the appended claim.

What we claim ist l A control device for an electric alarm comprising-a pair of contacts suspended from a relatively vibratory structure, one of saidcontacts being weighted and in contact with the other of said contacts whereby vibration of said structure breaks the circuit, a bent plate at the suspension ends of said contacts and adapted to engage said structure, and a screw passed through said suspension ends and adapted to press said bent plate against the said structure in order to adjust thc tension of said contacts.


Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2909614 *Sep 27, 1954Oct 20, 1959Goyette Louis EAutomatic resetting apparatus
US3671690 *Mar 16, 1971Jun 20, 1972Alarm Products Int IncVibrating switch
US4496809 *Oct 17, 1983Jan 29, 1985A B C Auto Alarms, Inc.Vibration sensitive trip switch for vehicle alarm system of the like
U.S. Classification200/61.49
International ClassificationH01H35/14
Cooperative ClassificationH01H35/144
European ClassificationH01H35/14C