Abstract:
A locking system for stopping a shopping cart includes a caster that can be selectively disabled when the cart encounters an electronic barrier. The caster includes a brake that is mounted on the frame of the caster. Also mounted on the frame are two receivers for separately receiving different signals from an electronic barrier. Respective decoders on the frame decipher lock commands in the signals, and a controller selectively activates the brake to prevent further movement of the cart in response to the lock commands. The electronic barrier can include an underground loop antenna and an above-ground RF beacon.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention pertains generally to electronic security and theft prevention systems. More particularly, the present invention pertains to alarm systems that detect when a vehicle encounters an electronic barrier. The present invention is particularly, but not exclusively, useful as an electronic security and theft prevention system that incorporates above-ground RF beacons, together with underground antennas, to establish an electronic barrier that will selectively disable a vehicle and thereby prevent its removal from a defined area. 
       BACKGROUND OF THE INVENTION 
       [0002]    For any of several reasons it may be desirable to control the movement of a vehicle as it is being used. For instance, it may be desirable to confine or limit the movement of the vehicle to within a specifically defined area. It may also be desirable to selectively disable the vehicle and thereby prevent its further movement within the defined area. This capability can be particularly important when the vehicle (e.g. a shopping cart) is temporarily loaned or provided to an individual (e.g. a customer) for movement through a defined area (e.g. a shopping center and its contiguous parking lot). Obviously, in such situations, a primary objective is theft prevention. 
         [0003]    To prevent the movement of vehicles from a defined area that is relatively large (e.g. several acres), practical considerations tend to dictate that the most cost effective way to control the situation is through the employment of electronic means. This then requires the generation of a signal, and an appropriate response to the signal. For theft prevention purposes, the activating signal needs to be generated at known locations (i.e. at the perimeter of a defined area, or at predetermined locations within the defined area). As is well known, such signals can be transmitted as electromagnetic waves between a transmitter and a receiver. 
         [0004]    Depending on how they are to be used, electronic barriers can be established in several different ways. For example, U.S. application Ser. No. 11/386,877, assigned to the same assignee as the present invention, considers activation signals that are transmitted from either above-ground RF beacons or from underground loop antennas (i.e. buried cables). When complex or extended perimeters are involved, however, using only one type transmitter may be less than completely effective. Instead, such situations may be best served using different kinds of antennas. For instance, along extended portions of a perimeter, an underground loop antenna (i.e. buried cable) may be preferable. On the other hand, RF beacons that can direct their beams to locations and areas around structures that would otherwise be difficult to cover by a buried cable may be more cost effective in specific situations. Other aspects also need to be considered. For example, unlike buried cable which is effectively stationary, RF beacons are more easily moved and can be used intermittently at several different locations. In any event, as is well known, underground loop antennas, and above-ground RF beacons, present different installation and different operational considerations. Importantly, different systems require different transmitters and different receivers. 
         [0005]    In light of the above, it is an object of the present invention to provide a locking system for disabling a vehicle that interacts with electronic barriers having either above-ground or underground transmitters. Another object of the present invention is to provide a vehicle locking (disabling) system that effectively prevents the removal of a vehicle from within a defined area whenever it encounters an electronic barrier. Yet another object of the present invention is to provide a vehicle locking (disabling) system that can be easily incorporated for use with other electronic inventory assessment and surveillance systems. Another object of the present invention is to provide a vehicle locking system that is easy to use, simple to manufacture, and comparatively cost effective. 
       SUMMARY OF THE INVENTION 
       [0006]    In accordance with the present invention, a locking system is provided for disabling a vehicle (e.g. a shopping cart) in a manner that causes little, if any, damage to the vehicle. The purpose is to prevent removal of the cart from a defined area or stop further movement of the vehicle in the area. Preferably the locking (disabling) system is affixed to the swivel frame of a caster on the vehicle (shopping cart), and it is activated whenever the cart encounters a pre-established electronic barrier. As envisioned for the present invention, this electronic barrier will be established by the combination of an underground loop antenna and an array of above-the-ground RF beacons. More specifically, the electronic barrier will be established along all, or part, of the perimeter of a defined area, and can include specific barriers at selected locations within the defined area. 
         [0007]    In detail, the locking system of the present invention includes a braking mechanism that is affixed to the caster yoke (frame). Additionally, a first receiver is mounted on the yoke (frame) for receiving a first signal, and a second receiver is mounted on the yoke (frame) for receiving a second signal. Each receiver is connected to a respective antenna, and to a respective signal decoder. The system further includes a controller that is connected to the first and second receivers, via their respective decoders, and to the braking mechanism. 
         [0008]    As envisioned for the present invention, an electronic barrier is erected to interact with vehicles (shopping carts) whenever the vehicle encounters the barrier. The result of this encounter is an immediate activation of the braking mechanism on the vehicle. This is accomplished by signals that are transmitted from the electronic barrier to the vehicle. In variations of this feature, rather than initiating a braking action, the signals that are transmitted from the barrier can be used to electrically cut off the power being used to move the vehicle (e.g. an electric cart). In still another aspect of the present invention, the transmitted signals can be used to activate audio-enunciators on the vehicle. For example, the operator of a wheelchair, or a person carrying a shopping basket, can be somehow informed of their proximity to the barrier and instructed what to do or where to go. 
         [0009]    For extended lengths of the electronic barrier, it is envisioned that a buried, underground cable will serve as a loop antenna for transmitting a lock signal to the vehicle. On the other hand, for isolated locations, complex constructions, or temporary uses, an above-ground RF antenna may be more appropriate. The present invention works well with either antenna. 
         [0010]    In operation, a vehicle (shopping cart) with a system of the present invention mounted on one of its casters is able to move freely through a defined area. For example, the defined area may be a shopping mall and its contiguous parking lot. Within this environment, when the vehicle encounters an electronic barrier that has been erected along the perimeter of the defined area, a signal from the barrier is received by one of the receivers in the caster. By way of example, a first antenna that is connected to the first receiver can be set to receive signals from an underground loop antenna. In this case, the signal (i.e. a first signal) will preferably have a frequency of approximately 10 kHz. This first signal is then passed from the first receiver to a first decoder where it is deciphered to identify a lock signal. If received, the lock signal can then be transmitted to the braking mechanism to stop the cart. Similarly, a second antenna that is connected to the second receiver can be set to receive signals from an above-ground RF beacon. In this case the signal (i.e. a second signal) will preferably have a frequency of approximately 2.4 GHz and a range of ten to fifty feet. This second signal is then passed from the second receiver to a second decoder where it is deciphered to identify a lock signal. As is done with lock signals received by the first receiver, the second lock signal will also be transmitted to the braking mechanism to stop the cart. 
         [0011]    Operationally, the signals that are transmitted from the electronic barrier can have selected signal strengths. For instance, the underground loop antenna can transmit its first signals for receipt by the locking system whenever the first antenna is within a predetermined distance (e.g. ten-fifty feet) from the underground antenna. Similarly, signals transmitted from above-ground RF beacons can be directed into specific locations for receipt by the locking system whenever the locking system is within approximately ten to fifty feet from the RF beacon. 
         [0012]    Additional aspects of the present invention that may be important for the operation of the locking system include the capability of establishing a time delay for a response to the lock signal. For instance, within the defined area, the vehicle may pass a location where it is not desirable to actually stop the vehicle, but rather limit its further use to a time certain (e.g. five minutes). Most likely, this time delay feature would be employed with the more mobile, above-ground RF beacons. In another aspect of the present invention, due to signal radiation considerations, it may be desirable to install the second receiver as a transceiver. If used in this capacity, the transceiver can be commanded to transmit identification, location, and time information about the vehicle to a central location. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which: 
           [0014]      FIG. 1  is a schematic diagram of a defined area in accordance with the present invention; 
           [0015]      FIG. 2A  is an elevation view of a caster for a shopping cart incorporating the present invention; 
           [0016]      FIG. 2B  is a view of the caster shown in  FIG. 2A  with the braking mechanism activated; and 
           [0017]      FIG. 3  is a schematic diagram of the component elements of an electrical circuit in accordance with the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    Referring initially to  FIG. 1 , an area for protection by the present invention is shown and generally designated  10 . As shown, the area  10  may include a shopping mall  12  and a parking lot  14 . The mall  12  and parking lot  14 , however, are only exemplary and are not limiting in their configuration. As will be easily appreciated, the area  10  can have many different configurations. 
         [0019]    As shown in  FIG. 1 , the area  10  is defined by an extended perimeter  16  that surrounds both the mall  12  and the parking lot  14 . An underground loop antenna  18  can be positioned along all, or along selected portions, of this perimeter  16 . For purposes of disclosure, the underground loop antenna  18  and the perimeter  16  are coincident and are represented together in  FIG. 1  by a dashed line.  FIG. 1  also indicates that a plurality, but at least one, above-the-ground RF beacon  20  can be positioned at selected locations within the area  10  (the RF beacons  20   a - c  are exemplary). As envisioned by the present invention, the underground loop antenna  18  is used to transmit a signal with a relatively low frequency (e.g. 10 kHz). On the other hand, the above-the-ground RF beacons  20  are used to transmit a signal having a relatively high frequency (e.g. 2.4 GHz). Together, the loop antenna  18  and the RF beacon(s)  20  create an electronic barrier for the area  10 . 
         [0020]    Still referring to  FIG. 1 , it will be appreciated that the present invention envisions a plurality of vehicles  22  (e.g. shopping carts) that can be moved around, within the area  10 . In accordance with the present invention, however, the carts  22  will become disabled whenever they contact the electronic barrier (i.e. loop antenna  18  and RF beacons  20 ). Thus, the carts  22  are not free to be taken away from the area  10 , or to be moved into prohibited locations within the area  10 . In accordance with the present invention, this objective is accomplished by providing each cart  22  with a wheel  24  that incorporates a locking system  26 . 
         [0021]    In  FIG. 2A  it will be seen that the wheel  24  of a cart  22  is mounted on a swivel frame  28 . More specifically, the swivel frame  28  is mounted as a caster on the cart  22  for rotation about an axis  30 . Further, the wheel  24  is mounted on the swivel frame  28  for rotation about an axis  32  that is substantially perpendicular to the axis  30 . The locking system  26  is then mounted on the swivel frame  28 . Functionally, the locking system  26  of the present invention is used to activate a braking mechanism  34  that will somehow disable the cart  22  from being moved. Although the braking mechanism  34  shown in  FIG. 2B  is a braking shell that will lift the wheel  24  from the ground, to thereby disable the cart  22  from further movement, other mechanisms can be used for this purpose. For example, a braking shell as disclosed in U.S. Pat. No. 6,125,972, which is assigned to the same assignee as the present invention, is suitable for use with the present invention. As will be appreciated by the skilled artisan, however, the braking mechanism  34  can be any device known in the pertinent art that will somehow prevent the wheel  24  from providing movement for the cart  22 . 
         [0022]    In  FIG. 3  the locking system  26  is shown to include an antenna  36  with an associated receiver  38 . Together, these components are provided to receive signals from the loop antenna  18  (approximate frequency 10 kHz). The received signals are then deciphered by a decoder  40  to determine whether the signal contains a “lock signal”  42 . If a signal, in fact, comes from the loop antenna  18 , it will have such a “lock signal”  42 . The “lock signal”  42  will then be sent to a controller  44 . Similarly, the locking system  26  also includes an antenna  46  with an associated receiver  48  for receiving signals from the RF beacons  20  (approximate frequency 2.4 GHz). These signals are then deciphered by a decoder  50  to determine whether they contain a “lock signal”  52 . If so, like “lock signal”  42 , the “lock signal”  52  is sent from the decoder  50  to the controller  44 . Whenever the controller  44  is in receipt of a “lock signal”  42 / 52 , a motor  54  is started by an activation signal  56  and a transmission  58  causes the braking mechanism  34  to disable the vehicle (cart)  22 . 
       Operation 
       [0023]    For the operation of the present invention,  FIG. 1  shows that the vehicles (carts)  22  are generally free to move about within the defined area  10  (i.e. within the space surrounded by the underground loop antenna  18 ). As specifically shown for the cart  22   a , however, whenever any cart  22  comes within a predetermined distance of the loop antenna  18  (e.g. ten-fifty feet), the antenna  36  and receiver  38  of the locking system  26  will receive a signal. In accordance with the above disclosure, the received “lock signal”  42  will then cause the controller  44  to activate the braking mechanism  34 . In turn, this activation will disable the cart  22   a  and cause it to stop at the perimeter of the area  10 , as shown. 
         [0024]    At selected locations inside the area  10 , it may be more advantageous to use RF beacons  20  than it would be to use a buried, underground cable, such as loop antenna  18 . This can be so for several different reasons, such as the cost and convenience considerations mentioned above. In any event, as illustrated by the plight of vehicle (cart)  22   b  in  FIG. 1 , if it is desirable to disable a cart  22   b  inside the area  10 , an RF beacon  20  may be employed for this purpose. In this case, whenever a cart  22  comes within a predetermined distance of an RF beacon  20  (e.g. ten-fifty feet), the antenna  46  and receiver  48  will receive a signal from the RF beacon  20 . Again, in accordance with the above disclosure, a received “lock signal”  52  will cause the controller  44  to activate the braking mechanism  34 . This will then disable and stop the cart  22   b  at any predetermined location within the area  10 . 
         [0025]    Although  FIG. 1  depicts separate carts  22   a  and  22   b , they may in fact be the same cart  22 . The point here is that all carts  22 , depending on where they may be within the area  10 , can be stopped either by the loop antenna  18  or by an RF beacon  20 . 
         [0026]    It is also to be appreciated by the skilled artisan that time delays can be programmed into the operation of the present invention. For example, the cart  22  may pass by an RF beacon  20   a  and receive an initial signal that includes a predetermined time delay (e.g. five minutes). Unless this signal is deactivated by passing near another predetermined RF beacon  20  (e.g. RF beacon  20   b ), the “lock signal”  52  will be passed to the controller  44  for activation of the braking mechanism  34 . On the other hand, if RF beacon  20   b  deactivates the signal, the cart  22  can continue moving within the area  10  without further incident. 
         [0027]    In an alternate embodiment of the present invention, the receiver  48  can be a transceiver. In this case, the transceiver  48  can be used to broadcast signals from a cart  22  over antenna  46 . These signals can provide information to a central control (not shown) as desired. For instance, the transmitted information may include identification data about the cart  22 , as well as its time and location within the area  10 . 
         [0028]    While the particular Caster-Lock With Dual Receivers as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.