US2825777A - Burglar alarm or the like - Google Patents

Description

BURGLAR ALARM OR THE LIKE Filed March 7, 1957 2 Sheets-Sheet 1 INVENTOR.

ATTORNEY March 4, 1958 w. P. GOULD 2,825,777

. BURGLAR ALARM OR THE LIKE Filed March 7', 195'? 2 Sheets-Sheet 2 FIG. 4

' INVENTOR. WAX/ une flfi BY 9 i Q! i s I ATTORNEY United States Patent BURGLAR ALARM 0R THE LIKE Wallace P. Gould, Forest Hills, N. Y., assignor to Merlite Industries, Inc., New York, N. Y., a corporation of New York Application March 7, 1957, Serial No. 644,544

8 Claims. (Cl. 200-45152) This invention relates to burglar alarms and, more particularly, to a novel detector switch unit for closing the circuit of a battery powered electric alarm when a window sash is moved vertically more than a pre-set amount.

While many commercial buildings and institutions are equipped with electric burglar alarm systems, the expense of installing such systems in homes and small business places has prevented their use in the latter. A common form of such an alarm system involves a normally closed electric circuit which is broken if a window or door is opened or window or door glass is broken, the open circuit causing dropping of a relay to energize an alarm circuit. The relatively extensive and specialized wiring and equipment is the principal factor making the cost of installing such a system too large to appeal to owners or tenants of private residences and owners of small businesses.

In accordance with the present invention, an inexpensive and simply installed burglar alarm is provided including a battery-powered electric alarm in circuit with an inexpensive detector switch unit adapted for mounting on a window frame and including a toggle-pivoted and preferably dielectric detector element engaged with a window sash. The unit includes a two-arm spring switch, with one arm being longer than the other and having the detector element pivotally mounted on its free end.

The unit is mounted substantially flush with the sash. The detector element is then engaged with the sash. Normally, the two-arms of the switch are engaged. However, the detector element, if pivoted to a position perpendicular to its mounting arm, projects outside the unit when the arms are engaged. Hence, when the detector element is moved to a horizontal position and engaged with the sash, its mounting arm is sprung away from the other switch arm to open the switch unit.

The detector element includes a cross-piece or pivot extending through a curled end of its mounting arm and having substantial lateral play therein. Thus, if the sash is moved only a slight amount, the detector element is not swung sufliciently to kick out of the horizontal position due to the spring pressure of its mounting arm. Should further sash movement occur, the detector arm snaps out of its substantially horizontal position and its mounting arm springs into engagement with the other switch arm to close the alarm circuit. A second and manually operated switch is included in the alarm unit to set the alarm or turn it oil.

For an understanding of the invention principles, reference is made to the following description of a typical embodiment thereof as illustrated in the accompanying drawing.

In the drawing:

Fig. 1 is a part elevation and part sectional view of the invention alarm arrangement as mounted in operative relation with a double hung window;

Fig. 2 is a partial sectional view of the detector unit as tripped by movement of the window sash;

2,825,777 Patented Mar. 4, 1958 Fig. 3 is an elevation view of the alarm with the front cover open;

Fig. 4 is an enlarged plan view of the detector with parts broken away;

Figs. 5 and 6 are views on the correspondingly numbered lines of Fig. 4;

Fig. 7 is a sectional view on the line 7-7 of Fig. 6; and

Fig. 8 is a schematic wiring diagram of the invention alarm.

Referring to Figs. 1 and 2, the alarm system of the invention comprises a detector switch unit 20 connected by a two-wire cable 60 to an audible alarm unit 40 described more fully hereinafter. While detector unit 20 must be mounted in a particular relation to the window or other opening to be protected, alarm unit 40 may be placed at any convenient or desired location by proper selection of the length of the connecting cable or cord.

In Figs. 1 and 2 unit 20 is shown in operative relation with the lower sash 11 of a double hung window 10 so as to be operated if sash 11 is raised more than a predetermined amount. The unit is mounted on the traming 12 of window 10 substantially flush with the sash 11 so that, if detector element 25 of the unit is moved to a horizontal position, it is spring-pressed against the window sash to open a normally closed switch 33. If on-oil switch 45 of alarm unit 40 is closed, and sash 11 is moved vertically a predetermined amount, element 25 will he pivoted counter-clockwise, switch 30 will snap to the closed position, and the alarm circuit will be closed. To cut out the alarm, switch 45 is opened.

Referring to Fig. 3, unit 40 comprises a channel shape metal base 41. suitably apertured for hanging on a wall or the like. A much deeper channel shape cover 42 is pivotally connected to base 41 at the upper end of unit 40 for swinging outwardly to permit access to the interior of the unit. Cover 42 has a grill 43 formed therein for sound transmission. An electrical sounder 50, which may be an electric buzzer or hell, is secured to the upper portion of base 41 by a metal screw or other metal fastener in such manner that one terminal of sounder 50 is grounded to base 41.

An angle bracket 44 is spot welded or brazed to base 41 below sounder 5i and carries, in electrically insulated relation, a bridging conductor 46 having spring contacts 4-7 at either end. Near the lower end of base 41, a second and much wider angle bracket 48 is welded or brazed thereto. A pair of contacts 51, 52 extend in insulated relation through either end of bracket 41. An insulated conductor 53 has one end electrically connected to contact 52 and its other end connected to one terminal of single-pole switch 45 mounted through a side wall of cover S2. An insulated conductor 54 connects the other terminal of switch 45 to the ungrounded terminal of sounder 59.

A wire clip 55 is electrically and mechanically connected to contact 51, and a second wire clip 57 is similarly connected to bracket 48 and thus grounded. Wires 61, 62 of two-wire cable 60 have bared ends engaged in clips 56, 57. Power for unit 40 is provided by a pair of unit dry cells 55 each inserted between a spring contact 47 and one of the contacts 51 or 52. Cells 55 are arranged in reverse relation so as to be connected in series by bridging conductor 46.

Referring to Figs. 4-7, detector unit 20 comprises two metal pieces 21, 22 formed to conjointly provide a mounting base 23 and a housing 24 for switch 30. Spring switch 30 includes a dielectric base 31 secured in the housing 24 by suit-able means such as rivets 32. Spring 0 contacts 34, 35 extend through base 31 and the bared Contact 34 is shorter than contact 35 and has an angular end 33 with a curved contact edge engaging contact 35 under pressure. The curved contact edge provides substantially point contact of end 33 with contact 35 facilitating free opening and closing of switch 30.

Contact 35 extends beyond contact 34 and has a free end 36 curled around a cross-bar 26 of dielectric detector element 25, bar 26 extending across an elongated opening midway of the ends of element 25. It will be noted from Fig. 7 that cross-bar 26 has considerable play in curled end 36.

After unit is secured in position as shown in Fig. 1, it is set by lifting end 27 of detector element to turn element 25 at right angles to contact 35. As detector end 28 of element 25 moves downwardly along sash 11, contact 35 is sprung away from end 33 of contact 34 to open switch 30. Switch 45 is then closed and the system is ready for automatic operation.

Referring to Fig. 8, the energizing circuit for sounder 50, when switch 45 is closed, is complete except for switch 3 being held open by detector element 25. When element 25 is tripped, as in Fig. 2, the alarm circuit is closed as follows: base 41, sounder 50, conductor 54, switch 45, conductor 53, contact 52, righth-and cell 55, contacts 47 and bridge 46, lefthand cell 55, contact 51, conductor 61, switch 30, conductor 62, and base 41.

Although the closure as illustrated in the drawing is a relatively vertically slidable window, it is within the province of this invention to apply the switch unit in association with an angularly movable closure, such as a swinging door or window. In such case the dielectric element 26 is weighted at end 28, so that once the swinging door or window is angularly displaced thereby releasing the pressure on end 27 of the dielectric element, said element oscillates by gravity so that end 27 thereof is displaced angularly upwardly and end 28 thereof is displaced angularly downwardly, thus releasing the pressure against spring 35, permitting the return of said spring to its circuit closing position by contacting with contact 34.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the invention principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. A detector unit for closing the circuit of a burglar alarm, said unit comprising in combination, a relatively elongated switch mounting arranged to be mounted in substantially flush relation to a movable closure to extend parallel to the direction of opening movement of said closure: normally closed switch supported in said mounting and including a dielectric base and a pair of relatively elongated normally spring engaged switch arms extending from said base substantially parallel to such direction of movement, one contact extending beyond the other contact; and a relatively elongated detector element pivoted to the free end of said one contact for swinging movement in a plane perpendicular to the direction of movement of said closure and having a detector end engageable with the closure; the distance of said detector end from the pivot axis of said element being greater than the normal switch-closed distance of the free end of said one contact from the closure; whereby, when said element is moved to extend toward the closure substantially normal to said one contact, the latter will be sprung away from the other contact to open said switch; movement of the closure causing the swinging of said element out of such normal relation to said one confact to provide for closing of said switch.

2. A detector unit in accordance with claim 1, wherein the closure is slidably movable, and the movement of the closure swings the element about its pivot.

3. A detector unit for closing the circuit of a burglar alarm, said unit comprising in combination, a relatively elongated switch mounting arranged to be mounted in substantially flush relation to a slidably movable closure to extend parallel to the direction of opening movement of said closure; a normally closed switch supported in said mounting and including a dielectric base and a pair of relatively elongated normally spring engaged switch arms extending from said base substantially parallel to such direction of movement, one contact extending beyond the other contact; and a relatively elongated dielectric detector element pivoted to the free end of said one contact for swinging movement in a plane perpendicular to the direction of movement of said closure and having a detector end engageable with the closure; the distance of said detector end from the pivot axis of said element being greater than the normal switch-closed distance of the free end of said one contact from the closure; whereby, when said element is moved to extend toward the closure substantially normal to said one contact, the latter will be sprung away from the other contact to open said switch; movement of the closure swinging said element out of such normal relation to said one contact to provide for closing of said switch.

4. A detector unit for closing the circuit of a burglar alarm, said unit comprising in combination a relatively elongated switch mounting arranged to be mounted in substantially flush relation to a slidably movable closure to extend parallel to the direction of opening movement of said closure; a normally closed switch supported in said mounting and including a dielectric base and a pair of relatively elongated normally spring engaged switch arms extending from said base substantially parallel to such direction of movement, one contact extending beyond the other contact; and a relatively elongated dielectric detector element pivoted intermediate its ends to the free end of said one contact for swinging movement in a plane perpendicular to the direction of movement of said closure and having a detector end engageable with the closure; the distance of said detector end from the pivot axis of said element being greater than the normal switch-closed distance of the free end of said one contact from the closure; whereby, when said element is moved to extend toward the closure substantially normal to said one contact, the latter will be sprung away from the other contact to open said switch; movement of the closure swinging said element out of such normal relation to said one contact to provide for closing of said switch.

5. A detector unit as claimed in claim 4 in which said element is a substantially fiat piece of dielectric material having an aperture intermediate its ends and a cross bar extending across said aperture; the free end of said one contact being curled about said cross bar.

6. A detector unit as claimed in claim 4 in which said cross bar has lateral clearance in such curled end to provide for toggle snapping of said element upon movement of the closure.

7. A detector unit as claimed in claim 1 in which said other contact has a free end bent toward said one contact and formed with a curved contacting edge for substantially point contact with said one contact.

8. A detector unit as claimed in claim 1 in combination with an alarm unit including an electric sounder, a pair of series connected dry cells and an on-off switch in series with said sounder, and a two-wire conductor connecting said alarm unit in series with the detector switch.

No references cited.

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