US2747177A - Burglar alarm system for a movable closure - Google Patents

Description

ay 22, 1956 A. G. KELLER BURGLAR ALARM SYSTEM FOR A MOVABLE CLOSURE 2 Sheets-Sheet 1 Filed Aug. 2, 1952 I l 1- L INVENTOR. ALBERT G. KELLER W ATTORNEY May 22, 1956 A. G. KELLER BURGLAR ALARM SYSTEM FOR A MOVABLE CLOSURE 2 Sheets-Sheet 2 Filed Aug. 2, 1952 BURGLAR ALARM SYSTEM FOR A MOVABLE CLOSURE Albert G. Keller, Forest Hills, N. Y., assignor to Holmes Electric Protective Company, New York, N. Y., a corporation of New York Application August 2, 1952, Serial No. 302,390

7 Claims. (Cl. 340-276) My novel jack and plug may be arranged in combination with all types of movable closures, but they are especially Well suited for use with corrugated or sectional overhead doors. In the past attempts to furnish a satisfactory burglar alarm device which could be readily installed on such a door and which would be responsive to a slight opening thereof have been unsuccessful.

It is an object of the present invention to provide a shorting jack and plug which form a portion of an electrical burglar alarm circuit and which can be arranged in combination with any movable closure so as to short that portion of the circuit when it is attempted to open the closure.

Another object of the invention is to provide a shorting jack and plug of the above mentioned type which are easily installed in combination with a movable closure, which can be easily disconnected from one another so as not to interfere with the authorized normal use of the closure and which can be readily connected or set when the closure is closed.

Still another object is to provide a shorting jack and plug therefor which are rugged, though small and light in weight, which are installable where they cannot be tempered with or rendered inoperative by a person outside the building, and which nevertheless can be readily seen from the inside to determine whether or not they are set.

The best mode in which it has been contemplated to apply the principles of my improvements is shown in the accompanying drawings but these are to be deemed primarily illustrative because it is intended that the patent shall cover by suitable expression in the appended claims whatever features of patentable movelty exist in the invention disclosed.

In the accompanying drawings:

Fig. 1 shows in full lines a pair of shorting jacks and plugs installed in combination with a corrugated or seetional overhead door, the door being closed and the plugs inserted in their respective jacks completing the circuit. The dotted lines show the positions of the jacks and plugs when the door is opened slightly, or when the plugs have been withdrawn for authorized use of the door.

Fig. 2 is a medial cross sectional view of a shorting jack;

Fig. 2a is a side view of a portion of a plug, partly in medial cross section;

Fig. 3 is another medial cross sectional view of a shorting jack showing a plug inserted therein, the plug also being shown in medial cross section;

Fig. 4 is a cross sectional view of the jack taken as on line 44 of Fig. 2;

Fig. 5 is a cross sectional view of the plug taken as on line 55 of Fig. 2a;

Fig. 6 is a diagram showing the burglar alarm system of which the shorting jacks and plugs are parts and illustrating the circuit condition when the plugs are inserted in the jacks;

Fig. 7 is a diagram similar to Fig. 6, but illustrating nited States Patent 0 2,747,177 Patented May 22, 1956 'ice the circuit condition when the plugs are separated from the jacks; i

Fig. 8 is another diagram similar to Fig. 6, but illustrating the circuit condition when the cable across the closure has been cut or broken; and

Fig. 9 is still another diagram which shows only that portion of the circuit associated with the closure, illustrating what happens in this portion when one of the plugs is pulled only partway out of its jack.

Referring now more particularly to Fig. 1 of the drawings, the closure being protected is a corrugated or sectional overhead door 10. The portion of the burglar alarm circuit protecting this door comprises a cable 12 leading from other parts of the circuit and entering one end of a jack A flexibly secured to a frame 14 at the side of the door 10 by a short length of chain 16 substantially as shown. When the door 10 is closed this portion of the alarm system is put in readiness by inserting a plug B into the other end of the jack A. This plug is located on the end of another length of cable 18 extending across the door and secured thereto by a series of fasteners 20. At the other end of cable 18 is a second plug B identical to plug B. This second plug is inserted in a second jack A identical to jack A and secured to the frame 14 on the other side of the door with a chain 16' in the same manner as the first mentioned jack. From this last mentioned jack a cable 12' leads to the next attachment on the premises in the overall circuit. The jacks B and B are fastened to the door frames 14 and 14' respectively'in such relation to the cable 18 secured to the door that when the latter is entirely closed the jacks must be tipped upward and extended toward the plugs as far as the chains 16 and 16 will allow before the plugs can be inserted. Spring detents within the jacks which will presently be described in more detail provide enough holding force to prevent the weight of the jacks from pulling away from the plugs.

When the door begins to open, as for instance when an unauthorized person attempts to enter the building, the cable 18 and plugs B and B on the ends thereof move upward with the door, and since the jacks cannot be so moved due to their chain connections with the fixed door frames, the plugs are pulled out of their jacks after the door has been opened a slight amount, the amount of opening required for this separation depending on the slack between the points where the chains 16 and 16 are fastened to the door frames and the two cable fasteners 20 on the door which are nearest the plugs. After being separated from the plugs by such an opening of the door, or when purposely disconnected to permit authorized use of the door, the jacks hang down from their chains as shown by the dotted lines in Fig. 1.

Referring now to Fig. 2 each jack A (or A) comprises an outer cylindrical casing 22 having at the end thereof a plug 24 provided with a suitable central hole 24a through which the cable 12 (or 12) enters the jack. A portion of this plug 24 is reduced in diameter at 24b to fit within the cylindrical casing 22 and to provide a shoulder 240 against which the end of the casing seats. One end of the short chain 16 (or 16) has secured thereto a ring 25 which passes through the head 26a of a bolt 26 screwed into plug 24. A lock washer 28 prevents bolt 26 from working loose in the plug. At the other end of the cylindrical casing 22 there is a somewhat similar plug 30 which is appropriately reduced in diameter at 30b to fit part way into the casing 22 and to provide a shoulder 3:00 to engage the end of the casing. These two end plugs are held in place by a rod 32 located within the casing and having one end threaded at 32a to screw into the plug 30. The other end of this rod 32 has an enlarged portion 32b with an axial hole 32c tapped therein to receive a bolt 34 passing through the plug 24. Tightening this bolt holds the ends of the casing 22 firmly against the shoulders 24c and 300 on the plugs 24 and 30, respectively. The central hole 30a in the end plug 30 is lined with a bushing 36 having an axial hole 36a, the outer end of which is flared to facilitate insertion and removal of the plug B (or B). The inner end 3617 of the bushing extends somewhat beyond the plug 30 and is reduced externally to receive an end plate 38a of a frame member 38. When the end plate has been slipped over this reduced end of the bushing the latter is peened over to secure this end plate to the bushing. A part of this end plate 38a "extends sideways from the bushing and has a hole through which the rod 32 extends. A shoulder 32d on the rod clamps the end plate to the plug 30. Thus the frame 38 and the bushing are held firmly in place.

The frame 38 is disposed at the center of the casing 22 and serves to'support the various electrical conductors and their insulating spacers. Adjacent the top side 3815 of the frame 38 is located a rectangular strip of insulating material 40. Next to this insulation strip 40 is a conductor strip 42, having a contact point 42a near the end thereof toward the plug 30. Adjacent to this conductor strip 42 is another shorter rectangular insulation strip 44. Next to this insulation strip 44 is another conductor strip 46, longer than the first mentioned conductor strip 42, having a small plate 46a welded thereon which can bear against the contact point 42a and having a ripple 46b at the end thereof which is located about opposite the side of the hole 36a in the bushing 36. Adjacent to this conductor strip 46 is still another insulation strip 48 of the same size as insulation strip 44, and next to this insulation strip 48 is another conductor strip 50 of the same size as conductor strip 42. The conductor strip 50 has disposed near its end a contact point 50a similar to contact point 42a on conductor strip 42. Another insulation strip 52 of the same size as insulation strips 44 and 48 separates conductor strip 50 from another conductor strip 54 which is longer than conductor strip 46 and extends to close by the inner end of bushing 36. This conductor strip 54 is bent at 54a as shown to bring its end 54b between theend 46b of the strip 46 and the edge of the hole 36a of the bushing 36. This conductor strip 54 also has welded to it a plate 540 which can bear against the contact point 50a on the conductor strip 50. Adjacent this conductor strip 54 is another insulation strip 56 of the same size as strips 44, 48 and 52. Adjacent this insulation strip 56 is a small plate 58 against which bear the heads of two bolts 60, these bolts passing through appropriate holes in this plate and all of the above mentioned strips, having suitable insulation tubes 62 around their stems and being threaded to screw into tapped holes 380 in the side 38b of the frame 38 to hold all these strips tightly together and to this frame.

A small pin 63 of insulation material is fastened to the conductor strip 42 and extends through a suitable hole 46c in the conductor strip 46. This pin serves to support the conductor strip 50 which might otherwise be bent permanently by the force of the plate 54c bearing against the contact'point 50a as will be understood.

The cable 12 which enters the jack at hole 24a contains two wires 12a and 12b. Wire 12a is electrically connected to the end 46d of the conductor strip 46 which end extends beyond the insulation strips 44 and 48 on 'the sides thereof, and wire 12b is electrically connected to the end 54d of the conductor strip 54. The conductor strips 42 and 50 are electrically connected together by a short piece of wire 64. A twine 66 tied to the cable 12 and to the rod 32 prevents the cable from being pulled out of the jack and thus insures that no strain will be put on the electrical connections.

Referring now to Fig. 3 this shows the plug B (or B) inserted in the above described jack. This plug comprises a metal jacket 68 filled with a plastic insulating material 70in which'there are embedded in separated relation two conductors 72 and 74. Conductor 72 is located at the center of the plug and extends out to the end thereof where it emerges from the plastic and forms a necked nipple 72a. From the neck of this nipple the surface tapers outward to form a cam-surface 72b (see Fig. 2a) beyond which and separated therefrom by an extended portion 78a of the plastic 70 is a metal ring 73 embedded in the said plastic 70. This ring provides a hard bearing surface for the end of the plug as it slides in the bushing 36 to save wear of the plastic 70a. Behind the ring 73 is a sleeve portion 74a formed at the end of the conductor 74 which is in turn insulated from the bearing ring 73 and from the conductor 72. The sleeve 74a is separated from the plug jacket 68 by another portion 7012 of the plastic 70. The outer end of the plug which is inserted in the jack is smaller in diameter than the end which the cable 18 enters, and this reduction in diameter results in a shoulder 68a on the jacket 68. This shoulder bears against the rim of the hole 36a in the bushing 36 when the plug has been fully inserted. A cover 76 of insulation material fits around the metal jacket 68, as shown, and is held in place by a set screw 6812. A spring 79, having a large diameter portion 79a which fits snugly around the end of casing 76 and having a small diameter portion 79!; which fits snugly around cable 18, prevents cable 18 from being sharply bent where it'enters the plug.

As the plug enters the jack the rounded nipple 72a first strikes the end 54b of the conductor strip 54 to the other end 54d of which the wire 12b of cable 12 is connected. This end 5411 being bent as shown further movement of the plug pushes it in a direction away from the axis of the jack, and as a consequence the plate 54c on the conductor strip 54 is separated from the contact point 50a on the conductor strip 50. As the plug continues into the jack this end 54b rides along the plugs cam-surface 72b, past the plastic 70a and the ring 73 and comes to rest on the sleeve 74a when the plug is fully inserted. Meanwhile as the plug is moving in to this fully inserted position the nipple 72a strikes the end 46b of the conductor strip 46 to the other end 46d of which the conductor 12a is connected. This end 46b having an indent therein as shown, further movement of the nipple pushes it away from the axis of the jack, and as a consequence the plate 46a on the conductor strip 46 is separated from the contact point'42a on the conductor strip 42. When the plug is in its fully inserted position the end 4612 of the conductor strip 46 rests in the neck of the nipple and this engagement serves to prevent the weight of the jack from separating it from the plug.

The cable 18 is comprised of two wires 18a and 18b identical to the wires 12a and 12b of the cable 12. Wire 18a is electrically connected to the conductor 72. Thus when the plug is fully inserted in the jack current in wire 12a flows through the conductor strip 46 to the nipple 72a from whence it flows along the conductor 72 and into the wire 18a of the cable 18. Likewise current in the wire 18b flows along the conductor 74 to the sleeve 74a from which it passes to the conductor strip 54 and leaves the jack through wire 12b. The direction of the flow may, of course, be opposite to'this, and if alternating current is used the direction changes with each cycle.

If theplug is'removed from the jack the current flowing in wires 12:: and 12b is short circuited. Current can then only How from wire 12a to conductor strip 46 and into conductor strip 42 because the removal of the plug allows the plate 46a on conductor strip-46 to-movc against contact point 42a on conductor strip 42. Also removal of the plug allows the plate 540 on conductor strip 54 to come in contact with point'50a on conductor strip50,'and conductor strip 42 'is connected to conductor strip 50 by wire 64. The other parts of the circuit shown in Figs. 6, 7'and 8 are arranged to be responsive to such and the plugs B and B are shown diagrammatically, the plugs are shown inserted in their respective jacks so that conductor 12a entering jack A is elfectively connected across the closure by conductor 18a to a corresponding conductor 12a leading from jack A, and conductor 12b likewise entering jack A is effectively connected across the closure by conductor 18b to a corresponding conductor .12b leading from jack A. In practice conductors 12a and 12b may enter another jack associated with another protected closure and so on for a number of such closures in series on the circuit, but after the last such closure the conductors are joined through a variable resistor 78 as conductors 12a and 12'b are shown to be joined in the drawings. Conductor 12b is grounded at ground point 80, and conductor 12a is connected through a galvanometer 82 to one side of a battery or other source of energy 84 the other side of which is grounded at a ground point 86. When the closure is closed and the plugs B and B are fully inserted in their respective jacks A and A battery 84 drives a current through the circuit comprising galvanometer 82, conductor 12a, conductor 18a, conductor 12a, variable resistor 78, conductor 12b, conductor 18b, and conductor 12b. The variable resistor 78 is then adjusted until this current is just suilicient to keep the grounded galvanometer pointer 82a half way between two galvanometer contact points 8222 and 820. Both these galvanometer contact points are connected through the windings of a relay 88 to one side 90:: of a second battery 90 the other side 90b of which is grounded. Relay 88 is arranged so that when it is energized its armature 88a releases and permits the closing of a switch 92 which completes an alarm circuit comprising the battery 90, switch 92, signal light 94 and bell 96.

Turning to Fig. 7, if the closure is opened and the plugs pulled out of the jacks conductor 12a is effectively connected to conductor 12b in jack A and current continues to flow through galvanometer 82, but because the resistance provided by those parts of the circuit beyond jack A have been removed this current is increased to the extent that the galvanometer pointer 82a moves until it touches galvanometer contact point 82c. This energizes relay 88 which in turn closes switch 92 and a signal is produced.

Likewise, considering Fig. 8, if there is an accidental break in the circuit supplied by battery 84, as at 94, or if an unauthorized intruder is able to cut the circuit in an effort to enter the premises or render the system inoperative, (for instance by cutting through the closure) this stops all current in galvanometer 82, whereupon galvanometer pointer 82a falls back against galvanometer contact point 82b. This also energizes relay 88 which in turn closes switch 92 and again visible and audible signals are produced.

Finally, if in an effort to enter the premises without disturbing the circuit, an intruder only partly dislodges a plug from one of the jacks an alarm will nevertheless be given. Thus in Fig. 9 the nipple 72a, illustrated diagrammatically, is shown to be in contact with the end 54b of conductor strip 54 after the plub B has been partly removed from its jack A, but it is clear that the circuit across the closure is broken despite this contact. Consequently current stops flowing in the galvanometer 82 and an alarm results as previously described.

One advantage of my improved invention lies in the fact that the jacks and plugs are easily installed on any movable closure. It is only necessary to have fixed frames which most closures have, to which the jacks may be secured. The cable 18 may be fastened to any closure.

Another advantage of my invention is that the jacks and plugs are small and hang out of the way so as not to interfere with the normal use of the door. At the same time, however, the jacks and plugs are rugged enough and the cable sturdy enough to withstand rough treatment without injury.

And still another advantage of my invention is that this portion of the alarm circuit is disposed where it can be easily set when the building is closed, and can be readily seen by one desiring to inspect it. For this reason it is also easily repaired. It cannot, however, be tampred with by one outside the building for when the jacks and plugs are properly installed the door cannot be opened far enough to enable any one outside the building to reach in and render them inoperative without first producing a signal.

I claim:

1. The combination with a sliding closure movable relative to a frame of an electrical burglar alarm circuit comprising electrical alarm signal means and a pair of elements adjacent each sliding edge of said closure, one element of each pair of elements being a jack and the other element being a plug, conductors connecting said signal means with the jack of one of said pairs of elements, the jack connected with said signal means being flexibly anchored to said frame, the plug of said one pair of elements being flexibly secured for movement with the closure, conductors extending across said closure and interconnecting said pairs of elements, the jack and plug of the other pair being flexibly linked with the closure and frame, a resistor, conductors connecting said resistor with said other pair of elements, the jack and plug of each pair being electrically separably connected so that upon predetermined movement of said closure the force of such movement effects separation of at least one pair of said elements so as to cause said signal means to give an alarm.

2. The combination with a movable closure having a frame at least partially surrounding the closure of a first conductor means stationarily attached to the frame and having at one end thereof electrical connecting means, a second conductor means fastened onto the closure for movement therewith and having a connecting means at one end thereof electrically separably connected with the first mentioned connecting means in such manner that movement of the closure separates the connector means and breaks the circuit, a signalling circuit including said first and second conductor means and connecting means whereby a signal is actuated upon movement of said closure.

3. The combination according to claim 2 wherein one of said connecting means is a plug and the other is a jack.

4. The combination according to claim 2 wherein the connecting means of said first conductor means is anchored to the frame by a chain whereby upon movement of the closure the chain is put in tension taking the strain off of the first conductor means.

5. The combination according to claim 3 wherein said first conductor means has a pair of conductor wires and said jack has a pair of spring contacts respectively connected to the terminals of said conductor wires, said plug having a pair of fixed insulated contact means respectively engaging said spring contact means when the jack and plug are coupled so as to complete the circuit through said first and second conductor means, said jack and said plug.

6. The combination according to claim 3 wherein said first conductor means has a pair of conductor wires and said jack has a pair of spring contacts respectively connected to the terminals of said conductor wires, said plug having a pair of fixed insulated contact means respectively engaging said spring contact means when the jack and plug are coupled so as to complete the circuit through said first and second conductor means, said jack and said plug, said jack having a pair of fixed contacts electrically connected together and so arranged as to be respectively contacted by said spring contacts when the jack and plug are separated so as to short the circuit from one of the wires of said first conductor means to the other of said wires upon such separation of the jack and plug.

7. The combination with a movable closure having a frame at least partially 'sourrounding the closure of a first conductor means stationarily attached to the frame and having atone end thereof electrical connecting means, a second conductor means fastened onto the closure for movement :therewith and having a connecting means at one end thereof electrically separably connected with the first mentioned connecting means in such manner that movement of the closure separates the connector means and breaks the circuit, a signalling circuit including said tfirst and second conductor means and connecting means whereby :a signal is actuated upon movement of said clo- .sure,.said first and second conductormeans each including a pair of Wires and said signalling .circuit 'being connected across said Wires of said first conductor means, a resistor connected across the wires of said second conductor means soas to complete and balance the circuit to the signalling m ans whereby no si l i g en whil the closure remains closed.

References Cited in the file of this patent UNITED STATES PATENTS

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