U.S. patent number 3,665,448 [Application Number 05/060,593] was granted by the patent office on 1972-05-23 for electronic shoplifting prevention system.
Invention is credited to Hugh A. McGlinchey, Robert L. Nathans.
United States Patent |
3,665,448 |
McGlinchey , et al. |
May 23, 1972 |
ELECTRONIC SHOPLIFTING PREVENTION SYSTEM
Abstract
A system for preventing shoplifting of articles through a first
exit area having an article removal detector positioned therein. A
small capsule bearing the designation DON'T REMOVE ELECTRONIC ALARM
is attached to an article to be protected, such as a dress, by
means of a safety pin. The capsule includes a wristwatch battery
which powers a single-stage, solid state oscillator which generates
an RF signal having a frequency F.sub.1 when the safety pin is
closed. A shoplifter who passes through the exit area with the
dress having the capsule fastened thereto will actuate an article
removal detector which will in turn actuate a pair of flash cameras
which are positioned to effectively photograph the entire exit
area. If the shoplifter unfastens the safety pin in the process of
discarding the radiating capsule within the store in an attempt to
thwart the system, a capsule removal detector will immediately
actuate a flash camera or annunciator to indicate unauthorized
removal of the capsule. Upon payment of the dress, the cashier
removes the capsule and very briefly causes an inhibit signal to be
transmitted to the capsule removal detector to prevent activation
of the capsule removal alarm devices during authorized removal of
the capsule. Another detector may be utilized at the cashier's
counter to detect secreted items bearing the capsule.
Inventors: |
McGlinchey; Hugh A. (Waltham,
MA), Nathans; Robert L. (Billerica, MA) |
Family
ID: |
22030500 |
Appl.
No.: |
05/060,593 |
Filed: |
August 3, 1970 |
Current U.S.
Class: |
340/568.1;
334/39; 331/65; 307/652; 340/572.1 |
Current CPC
Class: |
G08B
13/2434 (20130101); G08B 13/2414 (20130101); G08B
13/2448 (20130101); G08B 13/2431 (20130101); G08B
13/248 (20130101) |
Current International
Class: |
G08B
13/24 (20060101); G08b 021/00 () |
Field of
Search: |
;340/280,258R,258A,258B,258C,258D,307,276,283,224 ;328/5
;325/361 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Caldwell; John W.
Assistant Examiner: Wannisky; William M.
Claims
We claim:
1. A method of preventing the unauthorized removal through a first
area of articles contained within a second area comprising the
steps of:
providing within said first area an article removal detector having
an alarm indicator coupled thereto for producing an alarm
indication in response to the generation of RF signals within said
first area;
attaching RF transmission units to at least some of said articles
to be protected, which transmission units generate article removal
RF signals within said second area containing said articles which
are incapable of triggering said alarm indicator unless said
transmission units are positioned within said first area associated
with said detector to provide for containment of said articles
within said second area without triggering said alarm
indication;
producing a radiated transmission unit removal signal, in response
to the unauthorized removal of said transmission units from said
articles by an unauthorized individual; and
detecting said transmission unit removal signal and producing an
alarm indication in response to the detection of said transmission
unit removal signal to indicate unauthorized removal of said
transmission unit from a protected article.
2. The method of claim 1 wherein the step of producing said alarm
indication indicative of unauthorized removal of a transmission
unit from a protected article includes taking a picture of the area
containing the protected article.
3. The method of claim 1 wherein the step of producing said alarm
indication indicative of unauthorized removal of a transmission
unit from a protected article includes actuating an annunciator
which broadcasts the unauthorized removal.
4. The method as set forth in claim 1 wherein the step of producing
said transmission unit removal signal comprises altering a
characteristic of said article removal RF signal.
5. The method as set forth in claim 4 wherein said transmission
unit removal signal is produced by changing the frequency of said
article removal signal.
6. The method as set forth in claim 1 including the step of
detecting said transmission unit removal signal within said second
area and in the vicinity of a storage area within which said
articles to be protected are stored.
7. The method as set forth in claim 1 wherein said transmission
unit removal signal has a particular characteristic indicative of
the particular type of articles from which said transmission units
were removed to facilitate the location of an unauthorized removal
of a transmission unit from a protected article.
8. The method as set forth in claim 1 including the step of
inhibiting the production of a transmission unit removal alarm
indication, which would otherwise be produced by detecting said
transmission unit removal signal, during a period within which an
authorized individual removes a transmission unit from a protected
article.
9. The method as set forth in claim 8 wherein said inhibiting step
is performed by generating a radiating inhibit signal having an
inhibit characteristic which blocks the generation of said alarm
indication indicating unauthorized transmission unit removal which
would otherwise be produced in the absence of the generation of
said radiating inhibit signal.
10. The method of claim 1 further including the step of detecting
radiant energy produced by a secreted transmission unit located
only in the vicinity of a checkout station.
11. A method of preventing unauthorized removal through a first
area of articles retained with a second article containing area
comprising the steps of:
providing an article removal detector at said first area having an
alarm device coupled thereto for producing an alarm indication upon
the receipt of a first radiating signal by said detector which
exceeds a given threshold level;
attaching radiating transmission units to at least some of said
articles to be protected, which transmission units generate said
first radiating signal which is insufficient to trigger said alarm
indication produced by the alarm device coupled to said article
removal detector unless said transmission units are positioned
within said first area, so that the presence of said transmission
units in areas other than said first area will not trigger the
alarm device coupled to said article removal detector;
providing a transmission unit removal detector for detecting the
presence of a second radiating signal;
providing an alarm indication in response to the receipt of said
second radiating signal by said transmission unit removal
detector;
generating a second radiating signal in response to unauthorized
removal of a transmission unit from a protected article to trigger
the alarm device coupled to said transmission unit removal
detector;
generating a third inhibit signal during the period within which an
authorized individual removes a transmission unit from an article
to be protected; and
inhibiting the production of an alarm indication by the alarm
device coupled to said transmission unit removal detector in
response to the production of said third signal during the period
when authorized removal of a transmission unit from an article
occurs.
12. The combination set forth in claim 11 wherein the second
radiating signal is produced by removing an electrical component
from an oscillator positioned within the transmission unit.
13. The method set forth in claim 12 wherein said component is
removed by unfastening a fastening device which couples the
transmission unit to the article being protected.
14. An RF transmission unit for preventing the unauthorized removal
of an article from a given area and which may be readily attached
and removed from such an article to be protected comprising:
an RF oscillator for generating an RF signal over a prolonged time
period during which said RF transmission unit is attached to said
protected article;
a power source for operating said RF oscillator;
a housing for supporting said oscillator and said power source;
a fastening device coupled to said housing for fastening said
transmission unit to said article to be protected; and
control means for altering a characteristic of said RF signal
radiated by said oscillator upon the actuation of said fastening
device.
15. The combination set forth in claim 14 wherein a switch is
provided for coupling said power source to said oscillator,
together with means for preventing the opening of said switch once
said switch is closed.
16. The combination set forth in claim 15 wherein said housing
includes a flexible wall portion adjacent said switch to provide
for the closure of said switch by applying pressure to said
flexible wall portion.
17. The combination as set forth in claim 15 further including an
insulating member coacting with said power source for preventing
application of power to said oscillator; and
an actuating member connected to said insulating member for
enabling removal of said insulating member from said power source
upon the actuation of said actuating member.
18. The combination set forth in claim 17 wherein said oscillator
includes a frequency shifting component together with means coupled
to said fastener for connecting said frequency shifting component
to said oscillator when said fastening device assumes a first state
and for decoupling said frequency shifting component from said
oscillator when said fastener assumes a second state so that said
oscillator shifts in frequency upon the unauthorized removal of
said transmission unit from said article to be protected.
19. The combination set forth in claim 18 wherein said fastener is
electrically conductive and means are provided for coupling said
frequency shifting component to said oscillator when said fastener
is closed and for decoupling said frequency shifting component from
said oscillator when said fastener is opened.
20. The combination set forth in claim 18 further including an
electrical contact member positioned within said housing for
coupling said frequency shifting component to said oscillator when
said fastener is opened.
21. The combination set forth in claim 18 wherein said fastener is
a safety pin.
22. A method of preventing unauthorized removal through a first
exit area of articles contained within a second area comprising the
steps of:
attaching radiating transmission units to said articles to be
protected;
producing an article removal alarm indication in response to
radiation produced by the presence of said transmission units in
said first area but not in said second area;
producing a transmission unit removal signal upon the unauthorized
removal of a transmission unit from a protected article;
detecting said transmission unit removal signal; and
producing a transmission unit removal alarm indication in response
to the receipt of said transmission unit removal signal.
23. The method as set forth in claim 22 further including the step
of inhibiting the production of said transmission unit removal
alarm indication upon the authorized removal of a transmission unit
from a protected article.
24. The method of claim 23 wherein the step of inhibiting the
production of said transmission unit removal alarm indication
includes the transmission of an inhibit signal which inhibits the
production of said removal alarm indication.
25. The method of claim 22 further including the additional step of
detecting radiant energy produced by a secreted transmission unit
located only in the vicinity of a checkout station; and
producing a checkout station alarm indication in response to the
detection of said secreted transmission unit.
26. The method of claim 22 further including the step of
photographing said first area in response to the production of said
article removal alarm indication.
27. The method of claim 22 further including the step of
photographing said second area in response to the production of
said transmission unit removal alarm indication.
28. A method for preventing unauthorized removal through a first
exit area of a plurality of discrete articles contained within a
second storage area distinct from said first exit area, which
plurality of articles may be moved about within said storage area
without producing an alarm indication, said method comprising the
steps of:
attaching protective capsules to each of said articles to be
protected for enabling said protective capsules to move with said
articles as said articles are moved about within said storage
area;
producing an article removal alarm indication in response to the
presence of said protective capsules within said first exit area
but not within said second storage area due to unauthorized removal
of said articles from said second storage area;
producing a protective capsule removal signal upon the unauthorized
removal of a protective capsule from a protected article within
said second storage area;
detecting said protective capsule removal signal; and
producing a protective capsule removal alarm indication in response
to the receipt of said protective capsule removal signal.
29. The method as set forth in claim 28 wherein said article
removal alarm indication is generated in response to the receipt of
a predetermined minimum level of energy produced by the presence of
said protective capsules within said exit area but not within said
storage area.
30. The method of claim 28 wherein said protective capsule removal
signal is produced in response to the opening of a safety pin used
to readily attach said capsules to said articles to be protected.
Description
BACKGROUND OF THE INVENTION
This invention relates to the field of theft alarms and more
particularly to systems which inhibit the unauthorized carrying
away of articles from a given article storage area, such as the
interior of a store, museum or industrial warehouse.
It has been estimated that losses due to shoplifting in the United
States alone have exceeded 2 billion dollars per year, and it is
widely appreciated that the problem of shoplifting is an extremely
serious one. At present, floor-walkers are utilized to observe the
behavior of customers together with, in some cases, hidden video
cameras which are coupled to a display console which simultaneously
displays a number of scenes throughout the store, which scenes are
monitored by an observer. These procedures are quite expensive and
in the case of closed circuit television systems, a considerable
time lag occurs between the observation of suspicious behavior on
the tv receiver screen and action taken by a floor walker to
apprehend the shoplifter. In smaller stores TV systems and
floorwalkers are not utilized at all.
In the past, systems have been proposed for automatically detecting
the carrying out of shoplifted articles through an exit area. One
of the earliest approaches is to insert magnets or highly permeable
metallic members in articles to be protected and to provide a
magnetic flux change detector at an exit area which produces an
alarm as the article containing the magnetic material passes
therethrough. One problem with this approach is that an honest
customer triggers the alarm if a metallic object is being carried
on his person which, in manner similar to the magnetic material,
affects the flux detector. Another serious drawback to this
approach is that the shoplifter can remove the magnetic material
before passing through the exit area. Likewise with radioactive
tags which also might be dangerous to use in any quantity.
In U.S. Pat. No. 2,774,060 No. of Thompson, issued Dec. 11, 1956,
an oscillator is provided at the exit area and tags are fixed to
the articles to be protected, which tags include tuned circuits
having a resonant frequency which is equal to the radiating
frequency of the oscillator. If a tag which has not been removed by
the cashier is present in the vicinity of the oscillator, the
oscillator is loaded and such loading is detected by a threshold
device to sound an alarm. One disadvantage of this system is that
metallic objects carried by an honest customer could have a similar
effect on the oscillator, and, thus, the alarm would be sounded
erroneously. However, again as in the case of a magnetic detector,
a shoplifter may thwart the system by merely removing the tag
before secreting the article.
In U.S. Pat. No. 3,493,955 of Minasy, issued Feb. 3, 1970, a
transmitter is positioned in the exit area together with a receiver
which senses the presence of an RF signal having a different
frequency than the frequency of the signal produced by the
transmitter. An electronic circuit is attached to the article to be
protected, and, in the case of a shoplifter, is carried by him
through the exit area. This circuit includes a tuned detector which
activates an RF transmitter coupled thereto, so that the exit area
transmitter having a first frequency causes the energization of the
transmitter attached to the article which in turn produces an RF
signal having a second frequency which in turn is detected by the
receiver at the exit area to sound the alarm. One disadvantage of
this system is that the circuit attached to the article includes
both a receiver and a transmitter which increases the cost of the
units attached to each article. This factor is significant since
the store owner often has to purchase thousands of these units to
protect his merchandise. However, what is perhaps the most
important disadvantage of this arrangement, is that, again, the
shoplifter can merely thwart the system by removing the electronic
receiver-broadcaster unit attached to the article being protected
before stealing the article.
Thus, it is desirable to provide numerous capsules, which may be
attached to the articles being protected, which capsules include a
minimum of components so that mass production of such capsules may
be carried out economically. It is also important to provide
capsules which may be transported about within the store while
being attached to the articles and which cooperate with an exit
detector having a carefully controlled threshold sensitivity so
that radiating capsules transported within the store will not
inadvertently trigger the exit alarm. What is perhaps most
important is that the capsules be designed to be quickly and easily
removable from the articles to be protected by the cashier and in
the event that they are removed by a shoplifter, a capsule removal
alarm indication is immediately produced upon such removal, to
trigger a "Land" flash camera and/or actuate a tape recorder which
could broadcast a message such as "Security Problem in Dress
Department." However, it is also important to provide a system
which inhibits the aforementioned capsule removal alarm indication
during the brief period when a cashier removes the capsule from the
article. It is also advantageous to provide capsules which can be
rapidly and conspicuously affixed to dresses, for example, by means
of a safety pin and which bear a designation such as DON'T REMOVE
ELECTRONIC ALARM. Such an arrangement is necessary to cause an
honest customer not to remove the capsule and also serves as a
powerful deterent to keep shoplifters who are often perplexed about
electronics, from shoplifting the article.
SUMMARY OF THE PREFERRED EMBODIMENT
In accordance with a preferred embodiment of the invention, an
article removal detector triggers an alarm indication within the
exit area if a capsule, having an RF oscillator, which continuously
produces a first RF signal, is positioned within the exit area but
which will not trigger the alarm if such a capsule is positioned
anywhere within the article storage area. This alarm indication
actuates a pair of "Land" flash cameras which photograph the exit
area. The radiating capsule is affixed to an article to be
protected and is designed to immediately produce a second RF signal
upon being removed from the article by an unauthorized individual,
which second RF signal immediately triggers an unauthorized capsule
removal alarm. When an honest customer pays for the article, the
cashier momentarily generates an inhibit signal before removing the
radiating capsule from the article to be protected, which inhibit
signal briefly blocks the production of the capsule removal alarm
indication which would otherwise be produced by an unauthorized
removal of the capsule.
Other objects, features, and advantages of the present invention
will become apparent upon perusal of the following detailed
description taken in conjunction with the drawings in which:
FIG. 1 illustrates an overall schematic of the system; and
FIG. 2 schematically illustrates one of the capsules which is
attached to an article to be protected;
FIGS. 2a and 2b illustrate alternative detailed structure for FIG.
2.
DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION
In FIG. 1, a store area 1 is illustrated, and is defined by wall
members 2, 3, 4, 6, and 7. The store area contains article storage
subareas, one of which is illustrated by dress rack 8, having a
dress 9 hanging thereon. A radiating transmission unit or capsule
11 is affixed to the dress preferably by means of safety pin 12.
Details of the capsule are illustrated in FIG. 2. The capsule would
typically have a unitary, plastic housing portion 13 with a
flexible wall portion 14. The housing would contain a solid state
oscillator 16 which preferably would be of the simplest type and
would have a single stage and typically would radiate within the
Citizens Band, (e.g., 5.1 - 5.9 Mc. and at a power level of a few
milliwatts). Attached to the oscillator would be a frequency
determination circuit 17 which comprises inductor 18 and capacitors
19 and 21. A tiny battery 22, such as those utilized in
wristwatches, would be connected to oscillator 16 through a
"one-way" switch 23. Plastic housing 13 has a safety pin 24
embedded therein so that the capsule may be readily attached and
removed from the article to be protected. Upon receipt of the dress
at the store, a clerk would attach the capsule to the dress and
would thereafter squeeze the capsule to deflect flexible wall
portion 14 which would in turn close "one-way" switch 23 which
could not thereafter be opened without destroying the capsule.
While obviously numerous types of "one-way" switches may be
employed, an inexpensive switch would comprise a stiff metallic
strip 26 and a flexible metallic strip 27 having an end portion
which slightly overlays the terminal portion of the stiff strip 26.
A small block 28 would be affixed to the flexible strip 27 so that
when the capsule is squeezed, the flexible wall portion 14 deflects
flexible strip 27 against the stiff strip 26 and passes under the
stiff strip and is thereafter spring biased against the lower
terminal portion of strip 26. A segment of the lower right hand
portion of the safety pin is cut out at 29 and capacitor 21 is
soldered to the right hand portion of the safety pin, while the
lower left hand portion of the safety pin at 31 is electrically
coupled to a second capacitor 19 so that when the pin is closed,
the frequency determining circuit 17 comprises inductor 18 and
capacitors 19 and 21, and thus, the oscillator oscillates at a
first frequency F.sub.1. Details of the oscillator have not been
included since numerous types of solid state circuits could be
utilized which employ transistors, tunnel diodes, etc.
It is conceivable that on occasion a shoplifter would attempt to
destroy the capsule while it is still on the dress so that it might
not be able to trigger the various alarms within the system.
Although it is dubious that this could be done effectively, it
might be desirable to provide a capsule having a housing made of
rigid, virtually unbreakable material. A high impact plastic may be
considered. However, the store clerks must still close the
"one-way" switch in order to activate the capsule, and thus, a
variation in the previously discussed "one-way" switch may be
considered. In FIG. 2a batteries 22' and 22" are coupled in series
and are spring biased by spring 20 against contact member 20'. An
insulating member or tab 25a may be positioned between the positive
terminal of battery 22' and the negative side portion of battery
22". Obviously, other locations may be considered so long as the
tab initially breaks the power supply circuit. A wire or highly
tensile strength string 25b is attached to tab 25a and passes
through a bore hole 25c. This variant of the previously discussed
"one-way" switch is closed by pulling string 25c away from the wall
of the capsule, which in turn removes insulating tab 25a from the
interface of the battery terminals, thereby to complete the power
supply circuit.
In the aforementioned oscillator configuration the opening of the
safety pin removes capacitor 21 from the tank circuit. It is
conceivable that a clever shoplifter could place an additional
shunt wire between the left hand portion 31 of the safety pin and
the right hand portion 24 and thereafter open the pin. In this
instance, capacitor 21 would still be in shunt with capacitor 19
and thus the capsule removal detector might not be actuated. FIG.
2b illustrates a variant in the arrangement of FIG. 2 which would
thwart the possible effect of the shunting of the safety pin by a
clever shoplifter. In this arrangement, the upper wire portion of
the safety pin would be slanted as shown in FIG. 2b and would pass
through a narrow elongated slot formed in the housing of the
capsule. Capacitor 21' which corresponds to capacitor 21 of FIG. 2
would be disconnected from the tank circuit when the pin is closed,
because contact member 30 is positioned away from the heel or right
hand portion of the upper wire safety pin member as illustrated. In
contrast with the arrangement of FIG. 2, the lower left hand
portion of the safety pin is not coupled to the oscillator tank
circuit. Upon the unauthorized unclasping of the safety pin, the
aforementioned heel portion of the safety pin presses against
flexible contact member 30 so that capacitor 21' is now coupled in
parallel with capacitor 19' of the tank circuit. In this instance,
frequency F.sub.2 is lower than frequency F.sub.1 rather than the
reverse as explained in connection with the operation of FIG. 2.
With this variation in the tank circuit arrangement, the shunting
of the safety pin by a jumper wire would have no effect and the
capsule removal detector would be actuated upon unauthorized
unclasping of the pin.
An article removal detector 31 having a directional antenna 32 is
positioned within exit area 33. The article removal detector
typically comprises a resonant circuit tuned to frequency F.sub.1
which is generated by the capsule when the safety pin is closed.
The tank circuit is coupled to an electronic control device such as
a transistor through a detecting diode and an integrating
capacitor. The output circuit of the electronic control device is
in turn coupled to a threshold device which may be readily
controlled to close an alarm actuation circuit only upon the
production of a predetermined voltage drop across a resistor
coupled to the control device or the production of a given current
passed through a relay. Details of the article removal detector
have not been disclosed since numerous types are available in the
prior art. For example, U.S. Pat. No. 2,844,762 to Duryee, issued
July 22 1958, discloses an RF detection circuit which will turn on
electric lights upon the receipt of a particular RF signal having a
frequency to which the detector is tuned. The threshold sensitivity
of the detector may be readily controlled by potentiometer R.sub.2
so that only received RF signals of the required frequency and of a
predetermined strength will fire the threshold devices T.sub.1 and
T.sub.2 controlling the power actuation circuit which turns on the
lights. Another example of an RF detector is disclosed on page 535
of the Radio Amateur Handbook, published by the American Radio
Relay League, 1960 Edition. This circuit is designated as a field
strength meter and as in the case of the Duryee patent, includes a
resonant circuit coupled to an electronic switching device through
a detector diode and a capacitor which is in shunt with the control
circuit of the electronic switching device. In both of these
references an RF signal having the requisite frequency causes the
input tank circuit to resonate. Each half cycle causes the detector
diode to conduct which causes the capacitor coupled thereto to
commence to charge. In these arrangements the capacitor is in
parallel with a discharge path so that if very weak RF signals are
detected, the voltage across the capacitor will never charge up to
the point where the threshold device, such as thyratron T.sub.1 in
the Duryee patent, is triggered. However, if a relatively strong RF
signal is detected, the voltage will continue to rise across the
shunt capacitor C.sub.3 since during each half cycle the capacitor
is being charged to a greater degree than it is being discharged
and a voltage will be reached across capacitor C.sub.3 to fire the
threshold device T.sub.1, which in turn indirectly energizes relay
CR to close the controlled lighting circuit. Fine adjustmentof the
threshold level is provided in the reference patent by
potentiometer R.sub.2. This circuit also provides a 1 1/2 minute
holding period by virtue of R.sub.4, C.sub.5, C.sub.6, and T.sub.2
because the discharge path of C.sub.5 is a high impedance. This
holding period may be controlled by varying the value of R.sub.4.
In a similar manner the field strength meter disclosed in the Radio
Amateur's Handbook could be utilized by employing a potentiometer
in series with a threshold relay in the collector circuit of the
transistor. In this example the collector current will be a
function of the strength of the RF signal being received and the
relay will be actuated only after a predetermined amplitude of
current passes through the collector. The threshold or actuation
level of the relay may be varied by merely increasing or decreasing
the current flowing through the relay for any given level of
collector current such being typically performed by adjusting a
potentiometer coupled to the relay.
The system is first calibrated by carrying the radiating capsule
within exit area 33. The threshold level of article removal
detector 31 is first adjusted so that an alarm indication is
produced. The capsule is thereafter carried back through doors 33
and is positioned within the store area at position 34. If the
alarm indication is still produced, the article removal detector is
too sensitive and the potentiometer is adjusted until the threshold
level is increased to the point where the alarm indication is no
longer produced. Obviously, this potentiometer control should be
positioned so that access is not readily available thereto except
by means of a key, for example. The directional antenna aids in
preventing actuation of the exit alarm by a capsule positioned just
inside the store area at point 34. Now let it be assumed that a
shoplifter, not withstanding the warning on the capsule which reads
DON'T REMOVE ELECTRONIC ALARM, secretes the dress carrying the
capsule on her person and enters the exit area 33. Article removal
detector 31 will receive via its directional antenna an RF signal
F.sub.1, to which its tank circuit is tuned, which has a sufficient
strength to actuate the aforementioned threshold device. This
action will in turn immediately actuate a pair of "Land" flash
cameras 36 and 36' which take pictures of the exit area from
diverse positions so that it is highly probable that at least one
good photo of the shoplifter's face is recorded since she is
heading out of the doors. Also, if a guard is present at guard
station 37, the shoplifter would be immediately detained.
Additionally, if desired, a tape recorder 41 could also be actuated
to cause loudspeaker 42 to make an announcement, such as "Security
Problem within exit area A". For certain configurations such as may
be found in industrial applications, museums and even in stores,
such an announcement could thwart the theft. If desired, the
message could be broadcast at a remote intercept point. In fact,
"exit area" is intended to include, for example, an area
surrounding a showcase in a museum, which is not the exit from a
room. For example, the aforesaid exit area could be the exit of a
room in a museum or factory rather than the museum exit itself. The
threshold control is an important feature of our system since
obviously articles being carried about within store area 1 bearing
radiating capsules must not trigger article removal detector 31. On
the other hand, an object carried a few feet from a rifled showcase
in a museum should sound an alarm. Ease of control of the threshold
level results in easy adaptation of the system for different
applications.
Now let it be assumed that notwithstanding the warning on the
capsule, DON'T REMOVE ELECTRONIC ALARM, a shoplifter unfastens the
safety pin and discards the capsule within the store. As can be
seen from FIG. 2, unfastening of the safety pin removes capacitor
21 from the oscillator frequency determining circuit, which action
in turn reduces the product LC which in turn raises the oscillating
frequency of oscillator 16 to F.sub.2, as is obvious to those
skilled in the art. A capsule removal detector 43 preferably having
an omni-directional antenna 44 coupled thereto, is tuned to
frequency F.sub.2. The capsule removal detectors may be similar in
design to the article removal detectors positioned in the exit area
previously discussed. Immediately upon unclasping of the safety
pin, the threshold device coupled to capsule removal detector 43
triggers "Land" flash camera 46, which takes a picture of the area
in which the shoplifter is operating, and a tape recorder 47 again
causes a message such as "Security Problem in Dress Department" to
be broadcast over loudspeaker 48. Thus, an unauthorized capsule
removal alarm indication is produced immediately upon the removal
of the capsule and preferably right in the area in which the
shoplifter is operating. In the case of a large store, economical
considerations might preclude having the arrangement shown at
numerous article storage stations. A more centralized capsule
removal detector could be utilized at a remote station to trigger
an alarm which could alert a floorwalker via a portable paging
device. With this arrangement, the Dress Department capsules could
transmit an alarm signal of one frequency to the remote console and
the Men's Clothing Department could transmit another frequency to
the remote console so that a floorwalker is quickly advised as to
the location of the unauthorized removal. The capsules could be
color coded to indicate the goods to which they are to be attached.
Color coding may also be used to indicate battery expiration
dates.
Thus, when a shoplifter removes the transmission unit or capsule
from the protected article, a flash camera immediately takes a
picture of the shoplifter. The resulting flash alerts store
personnel along with an annunciator which includes the
aforementioned tape recorder 47 together with loudspeaker 48. The
resulting photograph which is developed on the spot would often
illustrate the shoplifter handling the goods suspiciously, and thus
might be valuable as means to secure an on-the-spot confession. It
is preferable that all of the cameras mentioned hereinbefore are
"Land" cameras so that a photograph can be developed rapidly for
"on-the-spot" use in the store. In the case of a museum
application, the photograph is itself powerful evidence of theft.
Likewise, if an employee is stealing a TV set from a warehouse.
Now let it be assumed that an honest customer carries the dress to
the cashier's counter 51 which normally consists of a desk bearing
a cash register 52. A problem is suggested with the aforementioned
system since the cashier must unfasten safety pin 24 in order to
remove the capsule from the dress. In the absence of further
circuitry, the aforementioned shift in the radiated signal from
frequency F.sub.1 to frequency F.sub.2 might trigger the capsule
removal alarm indication if capsule removal detector 43 is
positioned within range of the cashier's counter. Under certain
circumstances this might not be a problem because the threshold
level of capsule removal detector 33 might be set at a level which
would render the detector 43 out of range with respect to the
location of cashier's counter 51. However, often this would not be
the case; and, therefore, it may be necessary to take steps to
inhibit the production of a capsule removal alarm indication upon
authorized removal of the capsule by the cashier. One method of
performing this inhibiting step would be to provide a capsule
storage bin 53 having a pivotable lid 54 overlaying an entrance
slot 56. A cashier would be trained to raise pivotable lid 54 just
before removing the radiating capsule from the dress. Upon raising
lid 54 a limit switch 57 mechanically coupled to lid 54 would
activate an RF signal of frequency F.sub.3 immediately upon
actuation of the switch. An inhibit signal detector 58 having a
band pass filter or input circuit resonant to F.sub.3 would open a
switch somewhere within capsule removal detector 43 to prevent
actuation of the aforesaid capsule removal alarm indication by
detector 43. The inhibit signal detector, like the aforementioned
detectors, could comprise a tank circuit, a diode detector, an
integrating capacitor, and a control device such as a transistor
which in turn would be coupled to a relay which breaks the circuit
between the input circuit of capsule removal detector 43 and alarm
devices 46 and 48. As soon as the capsule is dropped into capsule
bin 53, lid 54 is closed, the RF signal F.sub.3 is no longer
generated and the inhibit condition is removed to thereby again
enable the capsule removal alarm device. The system might utilize
an RF shielded capsule bin to prevent a deposited capsule radiating
at frequency F.sub.2 from triggering the capsule removal detector
43. However, it is not necessary to utilize an RF shielded bin if
the width of the bin slot 53 is narrow enough to preclude allowing
the cashier to drop the capsule into the bin without closing the
safety pin. Normally, in the absence of an RF shielded bin, she
would close the safety pin to allow the capsule to be dropped
through the relatively narrow slot 53. Since the capsule dropped
into the bin is oscillating at frequency F.sub.1, and since the
cashier's counter 51 is not located in exit area 33, no alarm
indications would be produced.
However, optional use of another article removal detector 61 may be
considered which is similar to the aforementioned article removal
detector 31 positioned in the exit area. The threshold control
discussed hereinbefore would be set so that an alarm indication is
produced by article removal detector 61 only if a radiating capsule
is situated in the immediate vicinity of the cashier's counter.
Detector 61 would typically utilize warning lamp 63 rather than the
aforementioned annunciators or flash cameras. It is commonplace for
a shoplifter to pay for one article and secrete another article on
her person. In the event that such a shoplifter should be present
at the cashier's counter, and in the event that no other customers
are in the immediate vicinity of the cashier's counter, such a
secreted article bearing a capsule would produce an alarm
indication by virtue of detector 61 after removal of the capsule by
the cashier, associated with the article being paid for. The
lighting of warning lamp 63 could be utilized by having the cashier
phone a guard at guard station 37 or otherwise alert a floorwalker
who could intercept the shoplifter in the exit area, even in the
absence of a guard at guard station 37. If the optional article
removal detector 61 is utilized at the cashier's counter, it would
be necessary to shield the discarded capsules radiating at
frequency F.sub.1 from article removal detector 61. However, if the
optional removal detector 61 is not utilized, an RF shield need not
be employed. Another inexpensive arrangement which may be utilized
to segregate the discarded capsules would be to provide a large
wire loop or "key ring" instead of the aforementioned capsule
storage bin. The "key ring" would be typically situated under the
cashier's counter and would normally be supported by a detent
mechanism which would normally position the "key ring" away from or
under the cashier's counter. Before removal of the capsule the
cashier would be trained to pull the "key ring" toward her which
would snap the ring into a second detent position and which would
render it accessible to the cashier. This action would trigger the
aforementioned limit switch 55 which would generate the inhibit
condition as before. The capsule is removed by the cashier from the
protected article, and the pin is positioned to encompass the wire
loop of the "key ring", and the safety pin is thereafter closed
about the wire loop. This action ensures that the capsule will
thereafter radiate at frequency F.sub.1 just as in the case where
the capsule is attached to a dress on the dress rack and no alarm
indications are thereafter triggered by the capsules hanging from
the "key ring". This arrangement is very economical and inherently
ensures that the capsules do not thereafter radiate at frequency
F.sub.2 after removal of the inhibit condition. Additionally,
unless the optional article removal detector 61 is utilized, no RF
shielding is required. The "key ring" is thereafter pushed into the
counter so that the inhibit condition is removed since the limit
switch coupled to the "key ring" detent mechanism is again opened
to remove the inhibit condition.
The inventor believes that this system is highly practical because
of the powerful deterent effect of the capsules bearing the
designation DON'T REMOVE ELECTRONIC ALARM together with the flash
cameras and annunciators which are made visible rather than
hidden.
In summary, the present invention discloses a system which is
highly economical and well within the state of the art and which,
for the first time, should result in sharp reduction in thefts of
articles to be protected. This system may be utilized to protect
articles other than those being sold in stores although shoplifting
losses in the United States alone have been estimated to exceed 2
billion dollars a year. Expensive inventory stored in industrial
environments could also be protected since the carrying away of an
item of inventory would trigger a pair of flash cameras at the exit
area which would produce photographs of the thief. Likewise, the
system could be utilized in museums for protecting paintings, etc.,
and such systems could greatly reduce payroll expenditures of
museum guards, industrial guards, or floorwalkers.
Obviously, many modifications and variations of the present
invention are possible in the light of the above teachings. It is
therefore to be understood that, within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described. For example, the term "alarm" encompasses
virtually any indication which is useful in stopping a theft.
Likewise, the term "exit area" includes any forbidden zone in which
the radiating capsule should not pass through. The RF signal
generated by the capsule over a prolonged time period may not
necessarily be continuous but could be intermittent, e.g., one
burst of radiated power every 3 seconds.
* * * * *