US3594770A

US3594770A - Printed-circuit type security apparatus for protecting areas

Info

Publication number: US3594770A
Application number: US780931*A
Authority: US
Inventors: Conrad S Ham; Elwood R Horwinski
Original assignee: Lewis Engineering Co
Current assignee: Lewis Engineering Co
Priority date: 1968-10-28
Filing date: 1968-10-28
Publication date: 1971-07-20
Anticipated expiration: 1988-07-20

Abstract

A guarding apparatus responsive to violation of the security of an area or space, comprising a printed or similar gridlike circuit configuration of conductors, preferably of resistance characteristic, connected to form one or several continuous trigger circuits. The configuration may be in the nature of printed circuit panels arranged to enclose, preferably completely, the desired area of security, as by constituting part of the walls, floor, junction or connector boxes and the like. The circuitry is connected, as by a cable, to an energized electrical detector which may comprise an instrument movement and a bridge, whereby any shorting or breaking of one or more of the printed or similar conductors will result in a response by the instrument movement.

Description

United States Patent 1 1 3,594,770 {72] lnventors Conrad S. Ham [56| References Cited gr ga i Ch M h f UNITED STATES PATENTS S 3,|33,773 S/l964 Ecker 339/17 [21] Appl. No 780,931 Primary ExaminerJohn W. Caldwell [22] Filed 06.28.1968 Assistant Examiner-J. Michael Bobbitt (45] Patented July 20, I971 [73] Assignee Lewis Engineering Company Naugatuck, Conn.

[54] PRINTED-CIRCUIT TYPE SECURITY APPARATUS Attorney H. Gibner Lehmann ABSTRACT: A guarding apparatus responsive to violation of the security of an area or space, comprising a printed or similar gridlike circuit configuration of conductors, preferably of resistance characteristic, connected to form one or several continuous trigger circuits. The configuration may be in the nature of printed circuit panels arranged to enclose, preferably completely, the desired area of security, as by constituting part of the walls, floor, junction or connector boxes and the like. The circuitry is connected, as by a cable, to an energized electrical detector which may comprise an instrument movement and a bridge, whereby any shorting or breaking of one or more of the printed or similar conductors will result in a response by the instrument movement.

PATENTED JUL20 197i SHEET 2 OF 3 INVENTOR. Ham

on/ 4d wood P. Horn 0 A,

INVENT 5.

SHEET 3 [1F 3 {ax/Z PATENTEU JUL20 I975 PRINTED-CIRUIT TYPE SECURHTY APPARATUS FOR PROTECTING AREAS CROSS-REFERENCES TO RELATED APPLICATIONS l. Copending application of Elwood R. l-lorwinslti, Ser. Nov 755,203, filed Aug. 26, 1968, and having common ownership with the present invention.

2. Copending application of Elwood R. Horwinski, Ser. No. 761,725 filed Sept. 23, 1968, and having common ownership with the present invention.

BACKGROUND This invention relates to electrical security measures for guarding restricted areas or spaces, and more particularly to electrical equipment intended to signal or indicate unauthorized violations or trespassing of such areas.

Heretofore various systems such as light or infrared beams, electric eyes, high or lethal voltage guards and the like have been utilized to safeguard restricted areas, where unauthorized personnel were not desired. These systems have proved to be satisfactory in a number of instances, but drawbacks invariably existed. The high voltage installations constituted a hazard and danger to workers and other authorized personnel in the area. Some prior systems were vulnerable to power failure, others could be defeated too easily by the use of more or less sophisticated equipment in the hands of an unscrupulous person.

SUMMARY The above disadvantages and drawbacks of prior devices in tended to guard restricted areas are obviated by the present invention, and one object is to provide an improved area or space security apparatus adapted to guard both small and large areas, including electrical junction boxes for guardtype cables, which is readily fabricated by existing processes and especially effective and resistant to efforts intended to defeat its purpose. This is accomplished by the provision of a combination of interconnected printed or similar gridlike circuit configurations constituted of crossing insulated conductors which are connected so as to form at least one continuous trigger circuit or preferably a plurality of such circuits, said circuit or circuits being in turn connected to an electrical detection device which will indicate any alteration of the circuit characteristics. The conductor grid is arranged to enclose the space being protected or guarded, as by applying it to wall, ceiling and floor surfaces and the like, or incorporating it in wall and other panelling construction. For such purposes, the conductor grid is fabricated to be essentially flat or planar. Other grid configurations may be utilized, however, to suit particular situations.

Other objects and advantages reside in an improved area security apparatus as above indicated, which lends itself well to both existing and new constructions of buildings, rooms, vaults, safe boxes, junction boxes and the like; a security apparatus which is relatively simple and inexpensive, reliable and foolproof in operation, easily serviced, not subject to malfunctioning because of commercial power failure, wholly safe from the standpoint of fire and explosion hazard, damage to its environment or danger to personnel; and a highly effective security apparatus which is especially flexible in being adapted to a large variety of conditions and applications.

Other features and advantages will hereinafter appear.

In the drawings:

FIG. 1 is a diagrammatic representation of one form of area security device as provided by the invention.

FIG. 2 is a fragmentary section taken on line 2-2 of FIG. 1.

FIG. 3 is a fragmentary section taken on line 3-3 of FIG. 1.

FIG. 4 is a section through a rolled wallpaper having a printed-circuit grid, in accordance with the invention.

FIG. 5 is an edge elevation of a segment of plywood panelling having on one side a printed-circuit grid.

FIG. 6 is a fragmentary section of plaster or wallboard having on one side a printed circuit grid.

FIG. 7 is a schematic circuit diagram ofa sensitive detector circuit and control constituting part of another form of the invention.

FIG. 8 is a diagrammatic representation somewhat like that of FIG. l, but of another embodiment of the invention.

FIG. 9 is a perspective view ofa vault or small building lined with printed circuit grids and adapted to be guarded by the apparatus of the invention.

FlG. I0 is a perspective view of a strong box or safe lined with a printed-circuit grid according to the invention.

FIG. II shows a junction box lined with the printed circuit grids which are connected to two cable ends.

FIG. i2 is a fragmentary section on the line 1242 of FIG. I l.

FIG. I3 is a side elevational view of a simple cable construction having inner and outer braids, which is usable with the junction box ofFIGS. ill and E2.

FlG. M is an elevation showing a bag or tarpaulin which is lined with printed-circuit elements and connected by a cable to a detector station.

FIG. K5 is a circuit diagram of a simplified electrical detector as provided by the invention.

Referring first to FIG. i, there is illustrated a bridge circuit designated generally by the numeral 20, having

variable resistors

22, 24, 26 and 28 respectively in its four legs, the cornerjunctions ofthc bridge being designated 30, 32, 34 and 36. A source of energy or battery 33 is connected between the

corner junctions

32, 36 and a galvanometer or equivalent indicating instrument 40 is connected between the

corner junctions

30, 34.

In conjunction with the bridge 20, according to the present invention there is provided a novel, space enclosure having trigger circuits, said enclosure comprising an electrical grid formation 42 constituted of sets of parallel, printed-circuit conductors, preferably although not necessarily having high resistance, said conductors crossing each other in a close-knit configuration. The conductors are printed" on opposite sides of an insulating sheet 43 whereby they do not touch at the crossing points. The parallel conductors are connected at their ends so as to constitute at least one continuous trigger circuit.

In FIG. I there is shown a total of four continuous trigger circuits formed by the crisscross conductors of the grid 42. To effect this, the grid is formed to have on one side of the sheet 43 a zigzag configuration comprising a pair of spaced-

apart conductors

44, 46 and to have the other side of the sheet 43 a similar zigzag configuration comprising a pair of spaced-

apart conductors

48, 50. Preferably, as shown, the

conductors

44, 46 extend at right angles to the

conductors

48, 50.

A pair of leads is brought from each of these continuous trigger circuits. As shown,

lead wires

52, 54 constitute one such pair of leads; lead wires 56, 58 constitute a second pair of such leads;

lead wires

60, 62 constitute a third pair of leads; and lead wires 64, 66 constitute the fourth pair of leads. The pairs of lead wires are preferably brought from the grid configuration 42 in cable, this latter being indicated by the numeral 68 designating a broken outline.

Each pair of lead wires is connected to a different leg of the bridge 20, in series with the leg. Thus, the

wires

52, 54 are connected respectively to terminals A, B in the bridge leg having the resistor 22. The lead wires 56, 58 are connected respectively to terminals C, D in the leg containing the resistor 24 of the bridge; the

lead wires

60, 62 are connected respectively to the terminals E, F in the leg containing the resistor 26 of the bridge; and the lead wires 64, 66 are connected to the terminals G and H in the leg containing the resistor 28 of the bridge.

As a consequence, the four legs of the bridge respectively contain the four continuous trigger circuits of the grid formation 42. The formation 42 may be substantially fiat or planar, whereby it can constitute part (one side, for example) of a restricted or security enclosure. The grid 42 may, for instance,

comprise the single otherwise vulnerable wall of an enclosure whose other walls are especially impregnable. Or, the grid 42 may be considered symbolic, representing all six walls of an enclosure such as a vault, strongbox or the like, this being depicted in FIGS. 9 and 10. FIG. 9 depicts a walk-in vault, whereas the showing of FIG. 10 is that of a strongbox or safe. In each of these instances, the six confining surfaces or formations may be each constituted of a flat grid configuration similar to that indicated at 42 in FIG. 1. Four of the grid formations may be paired whereby there are two pairs, with the trigger circuits in each pair being series connected. The remaining two individual grid formations may be independent of each other, whereby the result is a total of four separate trigger circuits for connection to the four legs of the bridge 20. Appropriate selection of grid conductor resistances can be made, to provide for approximate equalization of the resistances of the four trigger circuits.

In the grid configuration 42 of FIG. I the conductor 44 forms one continuous trigger circuit, the conductor 46 forms a second continuous trigger circuit, the conductor 48 forms the third continuous trigger circuit and the conductor 50 forms the fourth continuous trigger circuit.

It will be understood that the grid configuration 42 may constitute, for example the front door panel 70 of the strongbox 72 shown in FIG. 10, or it may constitute the top or ceiling panel 74 of the vault 76 illustrated in FIG. 9. Or, the grid configuration 42 in FIG. I may be representative of an enclosure for all six sides of the strongbox 72 or vault 76. In FIG. 9 the detector station is indicated at 78, and in FIG. 10 it is indicated at 80. Such detector stations may contain the bridge circuit shown in FIG. 1. The cable 68 of FIG. I is given a similar character in FIGS. 9 and I0.

With the above circuit organization the bridge is placed in balance by appropriate adjustment of the

variable resistors

22, 24, 26 and 28. When the bridge is in adjustment, a null indication will be given on the instrument or galvanometer 40. Upon the system being thus balanced, any change in the characteristics of the printedconductor trigger circuits of the grid 42 will cause an unbalance of the bridge whereupon the instrument 40 will immediately indicate such unbalance signifying that some alteration of the grid protective system has occurred, presumably as a result of tampering or efforts to penetrate the restricted space.

From the foregoing it can be seen that we have provided a novel and improved area security apparatus wherein any tampering whatsoever with the conductors of the grid configuration, causing a severance of such conductors or a shorting of one conductor to another will result in the tampering being made known.

A more sophisticated detection circuit for connection to the printed-conductor trigger circuits of the grid 42, is illustrated in FIG. 7. In this figure, the tenninals A, B, C, D, E, F, G and H may be connected respectively to the

lead wires

52, 54, 56, 58, 60, 62, 64 and 66 which are shown in FIG. I as being connected to the terminals of the bridge 20 having the above lctters A through H. In other words, the circuitry shown in FIG. 7 is to be substituted for the bridge circuit 20 of FIG. I, in its entirety.

In FIG. 7, the variable resistors of the four legs are designated respectively 22a, 24a, 26a and 28a. The corner junctions of the bridge are designated respectively 30a, 32a, 34a, and 36a. The junctures 30a, 34a are connected to the terminals of a galvanometer 40a, and the

junctures

32a, 36a are connected respectively by

wires

82, 84 to a battery 38a, the wire 84 including an on-off switch 86. Accordingly, the bridge is energized from the battery 38a and may be placed in balance by suitable adjustment of the adjustable resistors, as with the case of the bridge 20 of FIG. I.

The galvanometer-type instrument 400 controls a movable shutter 88 having an aperture 90 in it. Adjacent the movable shutter 88 is an incandescent electric lamp 92 connected by

wires

94 and 96 and a resistor 98 to the battery 38a. Closing of the switch 86 will accordingly effect illumination of the lamp 104. a

In conjunction with the galvanometer 40a, lamp 92 and movable shutter 88 there is provided a phototransistor or light sensitive cell of the transistor-type, having a base 100, collector I02 and an emitter 104. The base I00 is connected through a resistor I06 and wire 108 with the positive supply wire 96 from the battery 38a. The emitter 104 is connected by a wire 110 to the bridge juncture 36a which has a connection with the positive supply wire 84 of the battery 38a. The en itter 104 is also connected by a wire 114 to a relay coil I16 which is in turn connected to an emitter 118 of a power transistor I20 whose base I22 is connected by wire I24 to the collector I02 of the light sensitive cell I05. A resistor 126 connects the base 122 of the power transistor I20 to the wire I14, said base being also connected through a resistor I28 and wire 130 to the collector 132 of the transistor I20. The wire I30 is also connected to the bridgejuncture 32a which goes to the negative supply line from the battery 38a. The relay coil I16 controls movable contacts 134 and I36, the latter being a holding contact engageable with a stationary contact 138 connected to the transistor emitter 118. The movable contact 136 is connected through a switch I40 to the collector I32.

The movable relay contact 134 connects through a wire I42 with a battery I44 which is connected to a switch 146 for controlling a signal or bell 148. The bell 148 is connected by a wire 150 to the stationary contact 152 which is cooperable with the relay contact 134.

As distinguished from the signal 148, a circuit control may be affected by connecting the wires I42 and 150 to a relay coil 154 and battery I56. Circuit-opening contacts 158 are actuated by the coil I54, and may be used to open any desired circuit.

Operation of the circuit of FIG. 7 is as follows: With the bridge balanced by suitable adjustment of the

resistors

22a, 24a, 26a, and 28a, the shutter 88 will be centralized, and light from the lamp 92 will strike the light sensitive cell 105. This effects a conductive path between the collector and emitter I02, 104 of the cell I05, thereby effecting a clamping action between the base 122 and emitter 118 of the transistor 120. In other words, the effect of light striking the cell is such that no appreciable voltage or potential difference exists between the base 122 and emitter 118 of the power transistor 120. In other words, the effect oflight striking the cell 105 issuch that no appreciable voltage or potential difference exists between the base 122 and emitter 118 of the power transistor 120. However, when the shutter I00 deflects to one side or the other, light will be shut off from the phototransistor I05, terminating the conductive path between the collector and emitter 102, I04. The clamping action thus ceases, and voltage can now exist across the resistor I26, meaning that a potential will exist between the base 122 and the collector 118 of the power transistor I20. Such voltage will render the transistor conducting whereby the relay coil 116 will be energized by current flowing through the collector and emitter. The result of this is that the relay coil 116, being energized, will actuate the

relay contacts

134, 136. The relay contact 136 is in the nature of a holding contact, and will maintain the relay energized regardless of shutting off of the transistor 120. The

relay contacts

134, 152 will effect c iergization of the bell 148 and actuation of the control i. 4, sounding an alarm and indicating that the bridge has been unbalanced, as by alteration of the printed conductors, ostensibly from tampering with the grid 42.

Another embodiment of the invention is illustrated in FIG. 8. Here there is shown a bridge 20!) having variable resistors 22b, 24b, 26b and 28b in its four legs. The opposite corner junctures 30b, 34b of the bridge are connected with an indicating instrument 40b, and the corner junctures 32h, 36!) are connected with a battery 3811. One leg of the bridge is broken and connected to terminals G, H which are connected by a cable 68b with terminals I, J of a grid configuration 42b. The grid configuration 42b comprises but a single continuous trigger circuit comprising the conductors on both sides of the insulating sheet 43!), said circuit having its two ends connected with the terminals I, J as shown. Thus, the grid 42!) is in only I plywood panel I64 as shown in FIG.

one leg ofthe bridge b. When the bridge has been balanced, any alteration of the characteristic or resistance of the grid configuration 42b will result in an unbalance, shifting the galvanometer 40b from its null position and indicating the abnormal condition. Such abnormal condition could be either a break in the conductor of the grid 421:, or else a short circuit condition between any two or more conductors of the grid.

The grid configuration 42 of FIG. I or 42b of FIG. 8 is as already stated, preferably in the nature of printed circuitry, shown in cross section in FIGS. 2 and 3. The grid configuration may be applied to wall paper or to wall panels. For example, in FIG. 4 the grid configuration 42 is applied to one side of wall paper 162. Or, the grid 42 may be applied to one side ofa 5, or to one side of a plasterboard panel 166, as shown in FIG. 6.

In place of the detector bridge circuits of FIGS. 1, 7 and 8, a simpler detector circuit may be utilized for connection to the grid configuration, as indicated in FIG. 15. In this figure, the terminals I and J correspond to the like lettered terminals of the grid-configuration 42b shown in FIG. 8. These terminals are connected by means of a cable 680 to terminals K and L of a detector circuit comprising a microammeter or current indicating device 168 connected in series with a variable resistor I70 and battery 172. This series circuit is connected to the terminals K and L, and the resistor 170 is adjusted to give a normal reading on the instrument 168. Any alteration of the characteristics of the grid 42b connected to the terminals 1 and .I will result in deflection of the instrument 168 away from its norm, whereby an indication will be had of tampering or other unusual condition involving the grid and'the restricted area which it surrounds.

The printed circuit grid 42 may be extremely flexible and rugged whereby it could be applied to one side of fabric. Thus, a bag or canvas such as that indicated at 176 in FIG. 14 could be provided with the grid, which is connected through a separable connector fitting I78 and cable 68 to a detector circuit unit 180 containing a bridgelike 20. The bag 176 could be anchored to the floor surface by a suitable clamp 182. Any

disturbance of the trigger circuitry will cause an indication to be given at the remote station 180.

The cable 68 may be constituted generally as shown in FIG. 13, comprising a signal wire core 184 and inner and outer insulated resistance-

wire braids

186 and 188 respectively. The

- braid wires may be connected so as to be included in the trigger circuits of the guard equipment, in series with the conductors of the grid 42. Details of the cable 68 are given in the above-identified copending application, Ser. No. 755,203.

FIGS. 11 and I2 illustrate an electrical junction box 190 which is guarded by a grid 42 lining its walls and cover. The box 190 has cables 68 connected to it. The braids of the cables are connected to the conductors of the grid 42 by plug-andsocket fittings I92 whereby continuity of the trigger circuits is had. One of the cables 68 in FIGS. II and 12 has its braid wires connected to a detector bridge such as the bridge 20 shown in FIG. 1. Thus, any disturbance of the grid 42 in the junction box 190 will be immediately detected in the manner already described above.

It will now be understood from the foregoing that we have provided a novel and improved guard apparatus which is responsive to violation of a security space or area, as occasioned by any alteration in the characteristics of the printed circuit grid placed around such area. The possibility of penetration of the grid being effected without altering its electrical characteristics and indicating such condition is extremely remote and unlikely. The guard apparatus as above set forth is seen to be relatively simple, sensitive in response and foolproof in operation, Relatively low voltages and currents are involved, which may be readily supplied by batteries, thereby eliminating hazard to authorized personnel in the area, and also eliminating dependence on commercial power sources. The apparatus is of relatively low tions readily adapt themselves to various constructional requirements, being easily incorporated in building panels, or being applied to existin building structures.

Variations and modr icat|ons are possible, and portions of the improvement may be used without others.

We claim:

I An area security apparatus comprising, in combination:

a. a grid constituted of conductors insulated from and crossing each other in a close-knit configuration,

b. said conductors being connected at their ends to constitute at least one continuous trigger circuit,

c. at least one pair of leads connected with said continuous circuit,

d. said grid being shaped to constitute at least part of an enclosure in which objects which are to be protected are disposed,

e. an electrical detection circuit having at least two terminals connected to said pair ofleads,

f. means providing electrical energy in said detection circuit,

g. said detection circuit including an electroresponsive device responding to the characteristics of the trigger circuit, thereby to register any alteration of said characteristics,

b. said grid comprising a planar printed-circuit configuration having a rigid insulating sheet and sets of conductors printed on both sides of said sheet, extending in different directions.

2. An apparatus as in claim 1 wherein:

a. the grid comprises four independent circuits,

b. said detection circuit comprising an electrical bridge,

c. said four independent circuits of the wire mesh being connected respectively in the four legs of the bridge.

3. An apparatus as in claim 2, wherein:

a. two of the independent circuits of the grid comprise conductors on one side of the sheet,

b. the remaining two of the independent circuits of the grid comprising conductors on the other side of the sheet.

4. An apparatus as in claim 1, wherein:

a. the grid comprises a single continuous circuit constituted of insulated sets of conductors disposed on opposite sides of the insulating sheet.

cost, and the grid configura-'

Claims

2. An apparatus as in claim 1 wherein: a. the grid comprises four independent circuits, b. said detection circuit comprising an electrical bridGe, c. said four independent circuits of the wire mesh being connected respectively in the four legs of the bridge.
3. An apparatus as in claim 2, wherein: a. two of the independent circuits of the grid comprise conductors on one side of the sheet, b. the remaining two of the independent circuits of the grid comprising conductors on the other side of the sheet.
4. An apparatus as in claim 1, wherein: a. the grid comprises a single continuous circuit constituted of insulated sets of conductors disposed on opposite sides of the insulating sheet.