U.S. patent number 3,596,265 [Application Number 04/737,567] was granted by the patent office on 1971-07-27 for tamper-proof shoplifting alarm.
Invention is credited to Percy A. Garland.
United States Patent |
3,596,265 |
Garland |
July 27, 1971 |
TAMPER-PROOF SHOPLIFTING ALARM
Abstract
I disclose a shoplifting alarm comprising a housing, a plurality
of circuit jacks mounted on a wall of said housing, a number of
loop segments attachable to said jacks for completing an alarm
circuit including alarm means and being contained within said
housing, means at the other end of each of said loops for securing
said loops to articles of displayed merchandise, and means for
preventing substantial separation of said loop segments from said
housing.
Inventors: |
Garland; Percy A. (McKeesport,
PA) |
Family
ID: |
24964411 |
Appl.
No.: |
04/737,567 |
Filed: |
June 17, 1968 |
Current U.S.
Class: |
340/568.2;
340/652; 340/568.4 |
Current CPC
Class: |
G08B
13/149 (20130101) |
Current International
Class: |
G08B
13/14 (20060101); G08b 021/00 () |
Field of
Search: |
;340/280,283,256,253
;339/36,147 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Caldwell; John W.
Assistant Examiner: Partridge; Scott F.
Claims
I claim:
1. A shoplifting alarm comprising a housing, a plurality of circuit
jacks mounted on a wall of said housing, a number of continuity
loop segments attachable to said jacks for completing a continuity
loop, an alarm circuit including alarm means and relay means, said
alarm circuit being contained within said housing, means at the
other end of said loops for securing said loops to articles of
displayed merchandise, means for preventing substantial separation
of said loop segments from said housing, said continuity loop and
said relay means being so coupled to said alarm means as to delay
energization thereof until a break occurs in one of said loop
segments, said relay means including a controlled semiconductor
having a triggering electrode, circuit means for connecting said
semiconductor in series with said alarm means and a source of
electric potential so that said alarm means are energized in the
conductive state of said semiconductor, a triggering circuit for
connecting said triggering electrode to said source, and a shunting
continuity circuit including said continuity loop segments
connected across at least a portion of said triggering circuit to
prevent the application of source potential to said electrode.
2. The combination according to claim 1 wherein said triggering
circuit includes opposing resistance means coupled to said source
and to said triggering electrode, and one of said resistance means
being coupled in series with said continuity circuit.
3. The combination according to claim 2 wherein each of said loop
segments includes electrical shield means extending along the
length thereof, and the other of said resistance means are
connected between said shield means and a loop conductor of each
loop segment so that severing or removing one of said loop
conductors or shorting said shield means thereto will trigger said
controlled semiconductor.
4. The combination according to claim 1 wherein a normally open
lock switch is coupled to said alarm circuit in parallel with said
controlled semiconductor such that momentary closure of said
normally open switch means resets said semiconductor to its
nonconductive condition to deenergize said alarm means after said
semiconductor has been triggered to energize said alarm means.
5. A shoplifting alarm circuit including a controlled rectifier
having a gating electrode, circuit means for connecting said
rectifier in series with alarm means and a source of electric
potential so that said alarm means are energized in the conductive
state of said rectifier, a triggering circuit for connecting said
gating electrode to said source, and a shunting continuity circuit
connected across at least a portion of said triggering circuit to
prevent the application of source potential to said gating
electrode, said continuity circuit including a plurality of
conductive loop segments shaped for securance to respective
articles of merchandise, said alarm means being connected to the
anode-cathode of said rectifier so that a break in one of said
segments causes said rectifier and said source to energize said
alarm means, said alarm means continuing to be energized through
said anode-cathode although a circuit is reestablished through said
one segment.
6. The combination according to claim 5 wherein said alarm circuit
includes resettable circuit means for actuating said alarm means
upon interrupting the continuity of one of said continuity loop
segments, electrically latchable means forming part of said relay
means for continuing the energization of said alarm means upon
restoration of said continuity, and resetting means for unlatching
said latchable means.
7. The combination according to claim 5 wherein said triggering
circuit includes opposing resistance means coupled to said source
and to said triggering electrode, and one of said resistance means
being coupled in series with said continuity circuit.
8. The combination according to claim 7 wherein said loop segment
includes electrical shield means extending along the length
thereof, and the other of said resistance means are connected
between said shield means and a loop conductor of each loop segment
so that severing or removing said loop conductor or shorting said
shield means thereto will trigger said controlled
semiconductor.
9. The combination according to claim 5 wherein output terminal
means are coupled to said circuit and are mounted in a wall of said
housing for external access, said output terminal being connected
to said circuit generally in parallel with said alarm means for the
actuation of auxiliary external alarm means or recording apparatus
connected to said terminal means upon energization of said alarm
means.
10. The combination according to claim 5 wherein a plurality of
shorting jacks each including a shorting continuity segment are
secured to said housing respectively adjacent each of said circuit
jacks and engageable therewith for bypassing unused ones of said
circuit jacks.
Description
The present invention relates to a shoplifting alarm system and
more particularly to an alarm system which is capable of indicating
a specific criminal intent relative to a specific article of
merchandise and which cannot be reset by the criminal or tampered
with by an insider for purposes of extinguishing or deactivating
the alarm.
It is well known that shoplifting, along with other types of crime,
is increasing at geometric rates and many businesses have suffered
tremendous losses from shoplifting. The total amount of merchandise
stolen by shoplifters amounts to an estimated one to three billion
dollars annually in this country. There may be as many as 150,000
shoplifting acts per week, with total business losses equal to 2--3
percent of nationwide gross sales.
Detection of shoplifting activities involves several serious legal
as well as technical problems. The laws of many states require that
the shoplifter be apprehended before he leaves the store and in
many cases at the precise location of the crime, i.e., at the sales
counter from which the merchandise was lifted. The use of an
adequate alarm system at the sales or display counter would apply a
substantial deterent to this type of criminal. For these reasons it
is extremely urgent that a suitable alarm or detection system be
provided at each display or sales counter and be arranged that the
tripping of the alarm shall indicate a specific intent on the part
of the shoplifter to steal a specific item of merchandise, rather
than a mere indication of removal of merchandise from some
indefinite location on the display counter. Known alarm systems
have not been capable of the requisite specific indication of
criminal intent.
Shoplifting alarm systems of many varieties have been developed in
the past. Many of these systems such as typified by U.S. Pat. Nos.
1,765,223 to C. C. Ferris and 1,105,504 to Gargon have found rather
little demand for their use as the merchandise could not be handled
by prospective customers of the store without setting off the
burglar alarm. These systems involved the use of normally closed
switches and the like which were held open by the weight of the
merchandise on a display rack or the like. In addition to the
obvious difficulties involved in prohibiting handling of the
protected merchandise, these alarm systems obviously could not
distinguish between inadvertent bumping or handling of the
merchandise and a specific criminal intent to lift or steal
specific items of merchandise.
Other known alarm systems involve the use of the electric leads or
cords of electrical appliances. The cords are inserted into plug
receptacles to maintain the alarm system in its preset condition.
Removal of the electric cord activates the alarm. This type of
shoplifting alarm is illustrated by patents to Cremer 3,090,948;
Lewin 3,127,597; Trayner 3,045,226 and Sliman 3,114,904 and
3,114,905. Although these alarm systems permit a limited customer
inspection of the merchandise, there is no way to differentiate
between inadvertent removal of the appliance plug from the alarm
receptacle and an intent to steal a given article. Thus, it is
virtually impossible to apprehend the criminal at the display
counter or elsewhere within the store. A further drawback is the
obvious fact that this type of alarm system is only useful for
electrical appliances.
The alarm systems typified by Lee 2,913,712 and O'Conner 883,335
are somewhat more sophisticated in that a closed loop or continuity
conductor is connected to an alarm circuit and is threaded through
or looped around various types of merchandise. In the Lee alarm for
example a number of single pole switches are connected in the loop
at locations respectively adjacent the items of merchandise. These
switches are frictionally maintained in their connected position,
with the result that under normal inspection of the goods, it is
likely that one or more of the switches may be inadvertently
disconnected to actuate the alarm. Again, it is extremely difficult
to distinguish between an inadvertent tripping of the alarm system
and an actual criminal intent.
I overcome these disadvantages of the prior art by providing a
shoplifting alarm system which is capable for use with all types of
merchandise. Although a continuity circuit is employed the circuit
is separated into discreet loop segments with each segment being
secured individually to an article of merchandise. The loop
segments are plugged into series-connected outlet jacks or other
suitable terminal means, mounted on a housing or casing for the
alarm circuit. A number of these outlet jacks desirably are
provided together with means for short-circuiting or bypassing
those which may be unused at any given time. Each loop segment is
secured to the associated article of merchandise and to the alarm
system such that considerable force is required to detach or remove
the loop segment. Thus, a specific criminal intent is denoted by an
easily recognizable act of violence such as breaking the loop
segment, cutting the segment or pulling the same with such force to
remove it from the alarm circuit casing. Thus, a would-be
shoplifter is in a very poor position to claim inadvertence in
setting off or tripping the shoplifting alarm.
The loop segments can be made in virtually any required length to
permit handling of the merchandise for normal customer inspection
without danger of inadvertently tripping the alarm system. In
addition, the loop segments can be easily disguised either for
aesthetic purposes or to conceal their function in an electrical
alarm circuit.
I accomplish these desirable results by providing a shoplifting
alarm comprising a housing, a plurality of circuit jacks mounted on
a wall of said housing, a number of loop segments attachable to
said jacks for completing an alarm circuit including alarm means
and being contained within said housing, means at the other end of
each of said loops for securing said loops to articles of displayed
merchandise, and means for preventing substantial separation of
said loop segments from said housing.
I also desirably provide a similar alarm system wherein said
circuit includes alarm means mounted within said casing, and output
terminal means coupled to said circuit and mounted in a wall of
said casing for external access, said output terminal means being
connected to said circuit generally in parallel with said alarm
means for the actuation of external recording means upon
energization of said alarm means.
I also desirably provide a similar alarm system wherein a shorting
jack is secured to said casing adjacent each of said circuit jacks
and engageable therewith for bypassing unused ones of said circuit
jacks.
I also desirably provide a similar alarm system wherein at least
one of said loop segments is connected to an auxiliary housing, an
additional number of said circuit jacks are mounted on said housing
and electrically connected to said one loop segment, and additional
loop segments are provided for said auxiliary housing.
I also desirably provide a similar alarm system wherein said alarm
circuit includes resettable circuit means for actuating said alarm
means upon interrupting the continuity of one of said loop
segments, electrically latchable means forming part of said circuit
means for continuing the energization of said alarm means upon
restoration of said continuity, and resetting means for unlatching
said latchable means.
I also desirably provide a shoplifting alarm circuit including a
controlled semiconductor having a triggering electrode, circuit
means for connecting said semiconductor in series with alarm means
and a source of electric potential so that said alarm means are
energized in the conductive state of said semiconductor, a
triggering circuit for connecting said triggering electrode to said
source, and a shunting continuity circuit connected across at least
a portion of said triggering circuit to prevent the application of
source potential to said electrode, said continuity including at
least one conductive loop segment shape for securance to an article
of merchandise.
During the foregoing discussion, various objects, features and
advantages of the invention have been set forth. These and other
objects, features and advantages of the invention together with
structural details thereof will be elaborated upon during the
forthcoming description of certain presently preferred embodiments
of the invention and presently preferred methods of practicing the
same.
In the accompanying drawings I have shown certain presently
preferred embodiments of the invention and have illustrated certain
presently preferred methods of practicing the same, wherein:
FIG. 1 is a perspective and circuit schematic view of one form of
shoplifting alarm system arranged in accordance with my
invention;
FIG. 2 is a partial isometric view partly in section of a display
counter illustrating one arrangement for mounting my novel
shoplifting alarm thereon;
FIG. 3 is a partial, similar view showing another form of the
system similar to that shown in FIG. 1;
FIG. 4 is a schematic diagram of one form of operating circuit for
my shoplifting alarm system;
FIG. 5 is a schematic view of another form of operating circuit;
and
FIG. 6 is a circuit schematic of still another form of my novel
alarm circuit.
Referring now to FIGS. 1 and 2 of the drawings, my novel
shoplifting alarm 20 includes a housing or casing 22 in which is
mounted a suitable alarm circuit such as that shown in FIG. 4 or
FIG. 5 and described in detail hereinafter. The housing 22 includes
at least one panel 24 having a number of circuit or output
terminals or jacks 26 mounted thereon. The jacks 26 are wired
internally of the casing 22. In this arrangement the terminals 26
can be in the form of female jacks each of which is provided with a
male bypassing or shorting plug or jack 28 conveniently chained or
otherwise secured to the panel 24 as denoted by reference
characters 30. Each bypassing plug 28 is internally wired to short
circuit the associated jack 26 when the latter is not in use, as
denoted by jack 26a.
A number of loop or continuity segments 32 are provided for
securance to various articles of merchandise 34 respectively by
means, for example, of cats paws 36 or other suitable mechanical
connection means adjacent one end thereof. The loop segments 32 do
not depend upon any internal electrical circuit or electrical leads
characteristic of certain types of merchandise. The other ends of
the loop segments 32 are connected to complementary jacks, for
example, male jacks 38, which are engageable with the panel jacks
26. When each of the panel jacks 26 is engaged either with a loop
segment 32 or a shorting jack 28 the load or continuity circuit for
the alarm system 20 is completed. Irrespective of the number of
loop segments 32 in actual use (whether equal to the total number
of panel jacks 26 or to some lesser number) a continuous circuit is
established by means of the loop segments 32, panel jacks 26,
bypassing jacks 28 (if used) and the internal circuit of housing 20
as described more fully hereinafter. As each loop segment 32 is
secured to only one item of merchandise, when a given loop segment
32 is broken or cut it is indisputable as to which article was
attempted to be shoplifted.
Each loop segment 32 in this example includes an insulated
conductor 40 the loop end or eyelet 42 of which can serve in
preparing the cats paw 36 mentioned above. A plastic covering or
insulation desirably is applied to the conductor 40 and simulates
the appearance of a string or cord to disguise the function of the
loop segment 32. In addition, an outer covering or sheath 44 can be
provided for the insulated conductor 40 for protective purposes or
to further disguise the function of the loop segment 32.
In the installation of the alarm system, as better shown in FIG. 2
the casing 22 can be mounted in an inobvious location such as on
shelf 46 underneath display counter 48. The loop segments 32
desirably are passed through aperture means such as one or more
openings 50 in the display counter 48 and thence to respective
items of merchandise as shown. To provide a maximum indication of
specific criminal intent, the casing 22 desirably is mounted with
respect to the one or more counter openings or apertures 50 such
that an application of pulling forces to any one of the loop
segments 32 straightens the intervening portion 52 of the loop
segments so that it is disposed at substantially a right angle to
the withdrawal direction of its jack 38. Thus, it is virtually
impossible to dislodge the jack 38 from its associated panel jack
36, as the casing 22 is rigidly secured to shelf 46 for example by
means of mounting brackets 54. The cable segment 32, then, together
with the specific item of merchandise secured thereto can only be
removed from the display counter 48 by breaking or cutting the loop
segment 32 which of course trips the alarm circuit as detailed
below. After the alarm circuit is tripped, it becomes electrically
latched so that the alarm cannot be extinguished by any attempt of
the shoplifter to reestablish the continuity of the loop segment,
for example by twisting together the broken or cut ends of the loop
segment 32.
In order to minimize tampering with the alarm system 20 by an
insider, the electrical supply for the casing 22 is provided by
means of a BX cable 56 or other suitably armored cable which is
wired directly to the entrance or junction box (not shown) through
the building structure for example wall 58.
Alternatively or in conjunction with the aforementioned angular
disposition of the casing 22 relative to the apertures 50, the
apertures can be sized to permit passage of the looped end 42 of
the associated loop segment 32 but to retain the larger diameter
loop segment jack 38 in the event that the latter does become
dislodged from the casing panel 24.
Depending upon size limitations, the jack panel 24 of casing 22
obviously can be enlarged to allow space for additional panel jacks
26 and additional loop segments 32. However, for use with a given
casing 22' as shown in FIG. 3, auxiliary housing means can be
provided for increasing the number of loop segments 32 which can be
electrically connected to a specified casing 22'. The auxiliary
housing means can afford shoplifting protection for adjacent
display counter or for additional merchandise on the counter 48.
One form of such auxiliary housing means includes a trough or
wire-mold structure denoted generally by reference character 60
connectable by means of loop segment 62 and jack 64 to any one of
the panel jacks 26'. The loop segment 62 and jack 64 thus can be
inserted in place of one of the loop segments 32 or one of the
bypassing jacks 28 of FIG. 1.
The loop segment 62 includes a pair of conductors 66 which extend
substantially the length of the trough 60 and are wired in parallel
to a number of trough jacks 68 each of which desirably is similar
to the panel jacks 26 or 26'. At each trough jack 68 a shorting
plug 70 is secured to the trough structure 60. The bypassing or
shorting jack 70 can be used in the same manner as that described
in connection with the bypassing jacks 28 of FIG. 1. The trough
structure 60 therefore supplies additional connection points for
additional loop segments 32' including their jacks 38'. The alarm
circuit, then, can be extended to include additional items of
protected merchandise.
The trough structures or auxiliary housings 60, for example, can be
mounted upon or beneath nearby display counters so that a number of
such counters can be controlled with my novel shoplifting alarm
system using a single casing 22 or 22'. Desirably, the trough
structure 60 is installed, in accordance with the teachings set
forth in connection with FIG. 2, so that the loop segments 32 must
be pulled substantially at right angles to their connection jacks
38'.
Referring now to FIG. 4 of the drawings, an exemplary alarm circuit
72 is controlled by the circuit continuity through loop segments
32' and, in this example, is generally supported within the casing
22. As explained previously the loop segments are electrically
secured to a number of series connected jacks 26' coupled to relay
74. The continuity circuit 76 thus formed is connected in series
with normally open relay contacts 77 and relay coil 80. This series
circuit is connected to transformer secondary 82 through conductors
84 and 86. A pilot lamp 90 is connected to the other normally
closed, stationary relay contact 78. While the relay coil 80 is
energized the movable relay contacts 87, 88 are held against a
first pair of stationary relay contacts 77, 78. The pilot lamp 90
and the relay coil 80 therefore are electrically latched in the set
or untripped condition of the relay 74 as denoted by the solid
outlines of the movable contacts 87, 88 in FIG. 4.
When a break occurs in one of the loop segments 32' the electric
circuit through the conductors 84, 86, the continuity circuit 76
and the relay coil 80 is interrupted. This trips the relay 74 and
allows the movable contacts 87, 88 to contact the other normally
closed pair of stationary contacts 91, 92. An attempt to
reestablish the continuity of the broken loop segments 32' fails to
reset the alarm circuit 72, as it is now impossible to establish a
circuit through the normally open relay contacts 77--87. Upon
deenergization of the relay coil 80 and the closure of relay
contacts a buzzer or other suitable alarm 94 is energized through
conductors 96 and 86 and relay contacts 88--92. At the same time
separation of relay contacts 96 and 86 extinguishes the pilot lamp
90. Separation of relay contacts 77 and 87 on the other hand
prevents relay coil 80 from being reenergized if the shoplifter
attempts to reestablish the broken connection in loop 32'.
In order to reset the alarm circuit 72 when desired, a normally
open lock switch 100 is coupled in bypassing relation to conductor
86 and continuity circuit 76 directly to the relay coil 80 through
conductor 102. After the broken loop segment or segments 32' have
been repaired momentary closure of the lock switch 100 resets the
relay 74, as the coil 80 closes contacts 77--87 and 78--88 to
reestablish a preset circuit path through the relay coil 80 and
continuity loop 76. The pilot lamp 90 and the lock switch 100 can
be mounted on the casing, as shown in FIG. 1 of the drawings.
When the alarm circuit 72 is tripped a shunting switch circuit 103
including a pair of plug receptacles 104, relay contacts 87, 91,
and conductors 105, 107, are shunted by relay contacts 87, 91 and
conductor 109 when relay coil 80 is open-circuited by a break in
the continuity circuit 76. For convenient access, the receptacles
104 can be mounted on the casing 22 as better shown in FIG. 1 and
can be used to connect a recorder surveillance camera, or both to
suitable power sources, when relay contacts 87, 91 are thus
closed.
A static alarm circuit, likewise arranged in accordance with my
invention, is illustrated in FIG. 5 of the drawings. In this
arrangement, a source of electrical potential such as battery 110
is connected in electrical series with a buzzer or other suitable
alarm 112 and a controlled semiconductor such as SCR (silicon
controlled rectifier) 114. In this example, the SCR cathode 116 is
connected to buzzer 112 through conductor 118 while the SCR anode
120 is connected to the negative terminal of source 110 through
conductor 122. With the arrangement thus far described the alarm
112 obviously will be energized when the controlled semiconductor
114 is in its conductive state. The conductive state or tripping of
the circuit 108 can further be indicated by pilot lamp 124
connected in parallel with the anode-cathode circuit of the
conductor 114. The lamp 124 is effectively removed from the circuit
when the SCR becomes conductive.
In this arrangement of the invention of the output or panel jacks
26' are connected in electrical series between gate or triggering
electrode 126 of the SCR 114 and its anode 120. A gate bias
resistance 128 is coupled in series with the continuity circuit 76.
A gate locking resistance 130 is connected between the SCR gate
electrode 126 and cathode 116. The aforementioned loop segments 32'
are connected to the jacks 26' and to display merchandise in the
manner described above with reference to FIGS. 1--3 of the
drawings. The jacks 26' likewise can be mounted on a housing or
casing such as that shown in FIG. 1.
As long as circuit continuity exists through the series-connected
loops 32', the opposing voltage developed across resistances 128,
130 prevents the application of triggering a potential to SCR gate
126. The SCR 114 remains, therefore, in its nonconductive state.
However, when one of the loop segments 32' is cut, broken or
removed the resulting open circuit effectively disconnects gate
bias resistance 128 and permits a triggering potential, developed
across gate locking resistance 130, to be applied to the gate 126.
As a result the SCR 114 fires and energizes the buzzer or other
alarm 112. When the SCR thus becomes conductive the pilot lamp 124
coupled in parallel therewith is extinguished, as noted
previously.
As is well known, once an SCR is gated, it is maintained or
electrically latched in its conductive state by an adequate flow of
anode-cathode current. In consequence, the alarm 112 continues to
sound irrespective of any impromptu repairs attempted upon the
continuity circuit 76' by the shoplifter or an "insider." The
circuits of FIGS. 4--6 with the exception of the loop segments 32'
can be mounted in suitable casings such as that shown in FIGS. 1--3
of the drawings.
To reset the alarm circuit 108, lock switch 100' is connected
across conductors 118, 122 in electrical parallel with the
anode-cathode circuit of the SCR 114. By momentarily closing the
lock switch 100' (as with a key entrusted to a reliable employee)
the SCR anode-cathode circuit is shorted out and the SCR is
returned or reset to its nonconductive state. The lock switch 100',
of course, is actuated only after restoration of continuity through
the loop circuit 76'.
A similar static alarm circuit is shown in FIG. 6 of the drawings.
In this arrangement a number of loop segments 132 are connected in
electrical parallel to static alarm circuit 134. The loop segments
132 for example can be connected to three element male jacks 135
which in turn are insertable into panel female jacks 136. The jacks
136 can be mounted on a suitable casing or housing in the manner of
the panel jacks 26 of FIG. 1.
In this arrangement of my invention each loop segment 132 includes
a loop conductor 138 and a conductive shield wire 140 or the like
extending the length of the loop segment 132 and around cats paw
loop 142 formed at the outward end thereof. The loop segment can be
furnished with a suitable covering 143 to conceal the components
thereof. The panel jacks 136 are wired as shown so that the shields
140 of the loop segments are connected in electrical parallel by
jack contacts 141 to one side of the gate locking resistance 130'.
The remaining terminals 145 of the panel jacks 136 connect the loop
conductors 138 and the gate bias resistance 128' to the other side
of the gate lock resistance 130'.
With this arrangement the interaction of the gate biasing and
locking resistances 128', 130' prevents the application of
triggering voltage to SCR gate 126'. The gate locking resistance
130', however, is shunted when the shield 140 of any one of the
loop segments 132 is shorted to the loop conductor 138, as when an
attempt is made to cut the loop segment 132. At such time the
voltage drop across bias resistance 128 is no longer opposed by
that across locking resistance, and the SCR is triggered to its
conductive state to energize the alarm 112'. The circuit 134 on the
other hand functions in much the same manner as the circuit 108 of
FIG. 5 when one of the loop conductors 138 is broken to disconnect
or open-circuit the gate bias resistance 128'. The circuit of F6
can be reset by means of lock switch 100'. The circuit of F6 not
only actuates a burglar alarm when one of the loop segments is
completely severed or broken, but also when an unsuccessful attempt
is made to cut one of the loop segments 132 with a knife or the
like. To ensure detection of attempted cutting in every direction,
the shield wire 140 can be spiraled around the loop conductor 138
of each segment 132 or can be replaced by a braided shield, for
example.
From the foregoing it will be apparent that novel and efficient
forms of tamper-proof shoplifting alarm systems have been disclosed
herein. While I have shown and described presently preferred
embodiments of the invention and have illustrated presently
preferred methods of practicing the same it is to be distinctly
understood that the invention is not limited thereto but may be
variously embodied and practiced within the scope of the following
claims.
* * * * *