Abstract:
An anti-theft system for a shopping cart comprises a collapsible front suspension mounted between the front side members of a base frame of the shopping cart, the front suspension including a support, a first set of casters mounted to the support, retractable pin means carried by the support and engagable with the side members of the base frame for maintaining the front suspension in an operative mode in which the first set of casters engage a supporting surface, a sensor for detecting a first external signal, apparatus functionally coupled to the sensor for transmitting an activation signal to the retractable pin means to cause retraction of the pin means and render the front suspension inoperative, and a second set of casters fixed to the base frame for preventing the cart from moving in a linear direction, when the front suspension is rendered inoperative.

Description:
This application is a continuation-in-part of application Ser. No. 09/083,476, filed on May 22, 1998, now U.S. Pat. No. 6,054,923, and claims priority from, and also incorporates by reference, the entire disclosures of, Provisional Patent Application Ser. No. 60/154,705 filed Sep. 18, 1999, and entitled CAPTIVE WHEEL TUBES (FOR FRONT WHEELS) AND ROTATING REAR CASTER WITH FORWARD FACING STOP DOG, and Provisional Patent Application Ser. No. 60/153,483 filed Sep. 11, 1999, and entitled FIXED DIRECTIONAL CASTERS. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to theft-thwarting devices to help prevent the loss of shopping carts from shopping stores. The invention disables operation of the front wheels of the cart as well as the rear wheels, and keeps the cart from being pushed out of the parking lot once the front wheels of the cart are disabled. 
     2. Description of Related Art 
     Millions of dollars are lost each year by grocery stores and shopping marts as a result of shopping cart theft. The expenses associated with shopping cart theft include cart replacement (with typical costs ranging from $55 to $85 per cart) and costs for retrieval of carts taken off the premises. 
     In applicants&#39; co-pending application, a shopping cart having novel anti-theft features was disclosed and claimed. In particular, the invention in that application addressed the problem of improper removal of shopping carts from the store&#39;s premises, and proposed as a solution a disabling apparatus comprising a combination of structural features borne by the basket supporting frame of the cart to render the cart&#39;s wheels inoperative upon actuation of the disabling apparatus. The object of the invention was to make it extremely difficult for a person having the intent to remove the cart from the store&#39;s premises by rolling it away. 
     The present invention is drawn to improvements over the previously presented subject matter, and incorporates additional shopping cart theft thwarting features. One major objective of the present invention is to defeat shopping cart theft attempts where the wheels of the shopping cart have been disabled but the thief still tries to remove the cart from the premises by tipping the cart so that the disabled wheels are removed from contact with the ground. In this way, the thief can then wheel the cart away on two wheels. 
     In response to the obvious need for a theft proof cart, several types of anti-theft devices for shopping carts have previously been developed. For example, U.S. Pat. No. 3,717,225 to Rashbaum (1973) discloses a piston rod and wheel lock device. This device includes a frame mounted actuator that locks one of the wheels of the cart. It does not eliminate the potential for the use of one bank of cart wheels rotating by lifting the disabled wheel from the contact with the ground. U.S. Pat. No. 5,315,290 to Moreno (1994) discloses an electronic wheel lock device. This device also fails to eliminate the possibility of leaning the cart to the side of the still active wheels. U.S. Pat. No. 4,2422,668 to Herzog (1980) discloses a collapsible sub frame causing the wheels to swing out of operative position. This device immobilizes the front wheels of the cart, but does not eliminate the possibility the cart can be leaned back, and rolled away using the rear wheels of the cart. U.S. Pat. No. 5,357,182 to Wolfe et al. (1994) discloses a braked wheel device. This device also fails to eliminate the possibility of leaning the cart to the side of the still active wheels once the cart has left the boundary of the parking lot. U.S. Pat. No. 4,524,985 to Drake (1985) discloses an arrest device for a wheeled cart, which relies on a hooking device in the parking lot, but does not appear to eliminate the possibility that the cart could be leaned to one side to avoid the hooking device. Similarly, U.S. Pat. No. 5,576,691 to Coaklet et al. (1996) discloses another form of a wheel locking device that also fails to prevent the removal of the cart by a user who can simply tip the cart onto its back wheels and roll the cart away. U.S. Pat. No. 4,577.880 to Bianco (1986) discloses still another form of a wheel locking device that fails to eliminate the removal of the cart by simply tipping the cart on to the back wheels and rolling the cart away. U.S. Pat. No. 4,772,880 to Goldstein (1988) discloses another form of the wheel locking device, disabling only one of the front wheels. U.S. Pat. No. 5,194,844 to Zelda (1993) discloses a proximity wheel locking mechanism. This device also fails to eliminate the removal of the cart by simply tipping the cart on to the back wheels and rolling the cart away. U.S. Pat. No. 4,591,175 to Upton (1986) discloses a magnetic wheel locking mechanism. This device also fails to eliminate the removal of the cart by simply tipping the cart on to the back wheels and rolling the cart away. 
     Many of the devices disclosed by these patents demonstrate that disabling only one wheel of a shopping cart is insufficient to completely immobilize the cart, for even if one wheel is disabled, the person removing the cart can continue to push the cart with sufficient force to override the traction of the locked wheel. Moreover, a shopping cart of the Herzog design, in which the two wheels of the front wheel assembly were disabled by allowing the sub frame of the cart to collapse around the front wheel assembly, failed to prevent the leaning of the cart backwards over, and rolling it away on, its rear wheels. 
     None of these previously known devices totally disables the cart. If one wheel is locked, a person intent on removing the cart from the premises can exert enough force to overcome the friction of the locked wheel. None of the devices heretofore known can prevent all the wheels of the cart from being disabled. If two wheels are disabled, as is taught by the Herzog patent, the cart can still be maneuvered by tilting the cart so that it can still be rolled away. 
     OBJECTS OF THE INVENTION 
     Accordingly, it is a principal object of the present invention to provide for a shopping cart disabling assembly which will thwart the removal of the cart from the shopping market&#39;s premises by preventing the cart from being rolled away from the premises. 
     Another object of the present invention is to provide a pair of redundant wheels on the shopping cart that work, in conjunction with the disabling assembly when it is actuated, to limit the range of motion in a forward pushing direction to purely circular motion. 
     Another object is to provide a shopping cart disabling assembly which can conveniently and easily be reset by any employee of the shopping market. 
     Still another object is to provide a set of non-swiveling casters fixed to the front of the frame of the cart that, when the forward wheels of the cart are disabled and the cart collapses, support the weight of the cart when the non-swiveling casters engage the ground, and thus prevent the cart from being pushed forward, the non-swiveling casters being oriented parallel to one another and at an angle to the sides of the cart frame, thereby causing the cart to roll around in a circle. 
     Yet another object of the invention is to provide stop dogs affixed on rear casters which will prevent rotation of the rear casters and stop forward motion of the cart when the front of the cart is elevated off the ground in an attempt to defeat the front wheel disabling device of the invention. 
     Yet another object of the invention is to provide a collapsible front wheel assemby for a shopping cart in which disablement of the front wheel assembly is triggered by a radio frequency signal emitted from an underground cable. 
     Still another object is to provide as great a deterrent to a would be thief whose object it is to remove the shopping cart, so that the only way the thief could remove the cart from the parking lot would be to physically carry the cart away. 
     Still another object of the invention is to provide a front wheel assembly on a shopping cart that includes fixed-direction casters attached to the frame of the cart and swiveling casters attached to a collapsible suspension, wherein when the collapsible suspension becomes disabled and non-functional, the wheels of the fixed casters absorb the weight of the cart and redirect the momentum of the cart to purely circular motion. 
     These and other objectives are accomplished by the present invention which includes a first, collapsible, front suspension assembly for use with a shopping cart and a second, forward motion defeating, suspension assembly mounted to the cart forwardly of the collapsible front suspension assembly. The cart&#39;s collapsible front suspension assembly comprises (1) a support having two opposing sides with surfaces, (2) a sensor comprising means for transmitting an activation signal when a trigger signal (such as a magnetic, audio, rf, infrared or optical signal) is detected, (3) two release pins moveably mounted to the support, the release pins comprising an outer end being extendible beyond the side surfaces, respectively, (4) activation means for retracting the release pins upon receipt of the activation signal such that the release pins outer ends are not extending beyond the respective side surfaces, and (5) two linearly aligned hinge pins extending past the side surfaces, respectively. 
     The invention may further comprise a release pin movement assembly comprising a pivoting member rotatably mounted to the support; and rigid linking members extending from the pivoting member to an inner end of the release pins, respectively, the release pin movement assembly arranged such that the release pins are retracted and not extending beyond the side surfaces, respectively. The release pin movement assembly may further comprise holding means for locking the pivoting member in a first position such that the release pins extend beyond the side surfaces of the support; and the activation means may further comprise springs disposed about the release pins and between the linking member and the support sides such that the springs urge the release pins to retract, thereby resulting in the pivoting member rotating to a second position, and a trigger wire comprising a metal that contracts when heated through electrical resistance from a battery. In a preferred embodiment of the invention, the trigger wire is comprised of titanium nickel. 
     In an additional aspect of the invention, a shopping cart may be retrofitted with an anti-theft device in a process comprising the steps of removing a front wheel assembly from a U-shaped base frame having a front member and two side members extending from the front member and terminating in first and second back ends; and providing a front suspension system comprising a collapsible front suspension assembly comprising two opposing side surfaces of a support; sensor comprising means for transmitting a trigger signal when a magnetic field or audio frequency is detected; two release pins moveably mounted to the support, the release pins comprising an outer end being extendible beyond the side surfaces, respectively; activation means for retracting the release pins upon receipt of the trigger signal such that the release pin outer ends are not extending beyond the respective surfaces; two linearly aligned hinge pins extending past the side surfaces, respectively, two front wheels mounted to an underside of the support; and two casters supported on the cart frame forwardly of the support, the two casters being disposed parallel to one another and arranged at an acute angle to the longitudinal axis of the shopping cart base frame. 
     In another aspect of the invention, a process of preventing shopping cart theft comprising the steps of providing the shopping cart with a disabling device such as that described above, and generating a radio frequency along a perimeter of an area. 
     Further, objects and advantages are to provide a shopping cart that can be used easily and conveniently without damage to the shopping cart, or injury to a person using the cart, which is simple to use and inexpensive to manufacture, which can be supplied in great quantities, not require separate manufacturing facilities, which can be used repeatedly and is easy to maintain. Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows an anti-theft shopping cart  10  according to the present invention in which the front wheel suspension asembly  24  of the cart is in a functional, operative, positions; 
     FIG. 2 shows the shopping cart base frame  12  (without the basket) with the front wheel suspension assembly  24  of the cart in a disabled, non-functional, “triggered” state and the fixed directional casters in an enabled, functional, state; 
     FIG. 3 shows details of the collapsible front suspension assembly  24  mounted to the base frame  12  of the shopping cart  10 ; 
     FIG. 4 shows the collapsible front suspension asembly  24  in operative and disabled states, and its functional relationship relative to the fixed directional casters; 
     FIG. 5 shows a tool used to reset the disabled collapsible front suspension of the shopping cart  10 ; and 
     FIG. 6 is a plan view of a parking lot showing marking patterns that can be used to delineate boundaries past which the front suspension assemblies of the carts will be triggered, as well as buried conduits which are used to generate a triggering signal according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings in which like reference numerals refer to like elements throughout the figures, a shopping cart  10  according to the present invention has a U-shaped base frame  12  comprising a front member  14  and two side member  16  and  18  extending rearwardly therefrom. The side members  16  and  18  have back ends  20  and  22  respectively. 
     A collapsible front suspension assembly  24 , shown in an untriggered, functional, state in FIG. 1 and a triggered, disabled, state in FIG. 2, extends between the two side members  16  and  18 . The details of the suspension assembly  24  are shown in FIG.  3  and will be described below. The front wheels  26  of the cart are supported on the underside of the suspension assembly  24 . A cover  25  sits atop the suspension assembly  24  and includes an opening  125  for external access to the “reset” component of the suspension assembly. A protective guard or shield  130  is mounted to the side members  16 ,  18  of the cart base frame to prevent undesired access to the suspension assembly  24 . An opening  135  is provided in the shield  130  at a position corresponding to the opening  125  in the cover  25  (the purpose of this opening is to be described below). 
     Also supported by the side members  16  and  18  at a more forward position (see FIGS. 2 and 3 in particular) is a fixed direction caster assembly  60  comprising a pair of wheels  62 ,  64  that are arranged at an acute angle to the longitudinal axis A—A of the base frame  12  and respective support members  66 ,  68  that mount the casters to the base frame  12  of the shopping cart  10 . Preferably, the support members  66 ,  68  are welded or bolted to the base frame of the cart such that they each are positioned adjacent the intersection of one side member and the front member  14  of the base frame. Preferably, the wheels  62 ,  64  are of the same or smaller diameter as the wheels of casters  26  attached to the suspension assembly  24 , and are arranged parallel to one another and at an acute angle to the longitudinal axis A—A of the base frame. 
     Referring now to FIG. 3, the collapsible front suspension  24  is depicted in it&#39;s collapsed state, and includes a U-shaped tray-like support  100  having two opposing sides  102  and  104  with exterior side surfaces  106  (only one side surface is shown in FIG.  3 ). The front wheels  26  are preferably pivotably attached to the underside of the support  100 . 
     The support  100  has two release pins  110  and  112  on opposing sides of the support  100  extending beyond the outer surfaces of the support  100  in the proximity of the rear end  50  of the support  100 . The two release pins are movably mounted relative to the support  100  (described below in greater detail) such that the outer ends of the pins are extendable beyond the exterior side surfaces  106 . This is to permit the outer ends of the pins to extend into holes formed in respective side members of the base frame  12  of the cart. The support  100  also has a pair of hinge pins  114 ,  116  extending along a front edge  51  of the support. Each hinge pin has an outer end extending beyond the exterior side surfaces  106  of the support  100 . The pin outer ends are linearly aligned and engage in corresponding openings in respectively adjacent side members  16 ,  18  of the shopping cart base frame  12 . Other embodiments of the invention may have a single hinge rod having opposing ends that perform a similar function as the two hinge pins. The support  100  can be secured directly to the U-shaped cart base frame  12  as for example by welding or bolts, or it can be secured to the cart frame using an intermediate member disposed between the outer surface of the support and inner surface of the side member, as was disclosed in applicants&#39; prior co-pending patent application. 
     Referring to FIG. 4, it can be seen that the non-collapsed, functional, suspension assembly is designated with the reference numeral  24 , and the collapsed, non-functional, suspension assembly is designated with reference numeral  24 ′ and is shown in phantom, dotted, lines. When the suspension assembly  24  becomes disabled and collapses, the fixed casters (only caster  64  is shown since FIG. 4 is a view of the forward region of one longitudinal half of the base frame) drop downwardly toward the surface  28 , placing the wheels  62 ,  64  of the fixed directional caster assembly  60  in contact with the surface  28 , and thereby inhibiting the shopping cart  10  from being pushed forward for any substantial distance. In fact, once the wheels  62 ,  64  make contact with the surface  28 , motion of the shopping cart is constrained to circular motion only, in the direction in which the two wheels  62 ,  64  are directed, as long as the collapsible suspension assembly remains disabled or collapsed. 
     It is to be understood that when the collapsible suspension becomes disabled, the weight of the shopping cart is absorbed by the wheels  62 ,  64 , and the momentum of the cart is redirected circular motion only. Furthermore, the combination of the collapsible suspension assembly with the fixed directional caster assembly prevents destruction of cart caster components when the collapsible suspension assembly becomes disabled, as is the case with various devices taught by the prior art, and also prevents injury to customers by absorbing the weight of the cart and smoothly redirecting motion instead of abruptly ceasing motion. 
     The suspension assembly of the cart is disabled by a triggering signal, such as an audio, magnetic or radio frequency signal, which is detected when the cart is pushed past a signal emitting member, such as an underground cable or a line-of-sight emitter. A sensor  130 , mounted on the support  100 , detects the triggering signal. The sensor transmits a disabling signal via a conduit  135  (eg, a wire) when a triggering signal is detected. Designs for sensors of the type needed to detect a triggering signal are well know in the art. Preferably, the sensor  130  and disabling signal produced thereby is powered by batteries carried by the suspension assembly. 
     The two release pins  110  and  112  in the suspension assembly  24  are moveably mounted to the support  100  such that outer ends of the pins are extendible beyond the exterior side surfaces  106 . This permits the outer ends to extend into the holes formed in side members  16 ,  18 . When a triggering signal is sensed, the sensor  130  transmits a disabling signal to activate the mechanism for retracing the pin ends. The disabling signal preferably is an electrical current from the batteries to a titanium nickel wire  142 . This alloy has the property of contracting when heated. Thus, the current heats the wire and causes it to contract. The invention also contemplates the use of other resistive materials that contract upon heating. The contracting of the wire  142  moves a member  144  about a pivot point  146 . As the member  144  pivots, a protrusion  148  on the member  144  disengages from a pivoting member  150 . As a result, the member  150  pivots, thereby moving a notch  152  from engagement with the side of a second pivoting member  154 , which, in turn, is rotatably mounted to the support  100 . 
     The release pins  110  and  112  are connected to the pivoting member  154  via rigid linking members  156  such that when the pivoting member  154  pivots in one direction, the pins  110  and  112  are driven to extend beyond the exterior side surface  106 , and when the pivoting member  154  pivots in an opposite direction, the pins  110  and  112  are retracted behind the surface  106 . Springs  158  are disposed about the release pins  110  and  112  and between the respective linking member  156  and the support sides  104  such that the springs urge the release pins to retract. This arrangement permits the release pins to retract when the notch  152  is removed from the side of the second pivoting member  154 . 
     To reset the release pins  110  and  112  into their extended position, the pivoting member  154  is rotated or pivoted such that the release pins extend beyond the exterior side surfaces  102 ,  106  and the notch  152  is reengaged with the side of the pivoting member  154 . This is accomplished by engaging a tool with the tamper proof screw  160  and rotating the pivoting member. 
     The shopping cart  10  preferably also has theft-deterring wheels or casters at the rear end of the cart. These casters can be of two types—a pivotable caster  70  mounted for pivoting movement about its attachment to the base frame of the cart, or a fixed caster  80  fixedly mounted to, and at an attachment location on, the base frame of the cart (see FIGS.  1  and  2 ). Insofar as a pivotable caster typically can pivot freely about the attachment spindle with which it is attached to the base frame of the cart, preferably each caster  70  is provided with a forward facing stop dog that will face rearwardly when the cart is tilted backward onto its rear casters and the caster  70  pivots about it spindle 180°. 
     Preferably, each pivotable caster  70  (a cart may have two pivotable casters at the rear end) on the cart includes a U-shaped strap  72  which is positioned in a forward-facing manner, while each fixed caster  80  on the cart includes a U-shaped strap  82  facing rearwardly. The straps  72 ,  82  are provided as a means of preventing the cart from being moved in the direction in which the strap faces. Thus, the strap functions as a “stop dog” to further inhibit the shopping cart  10  from being pushed forwardly or rearwardly after the front suspension assembly has been disabled. Non-rotatable, fixed, wheels are prevented from rotating in a plane that is parallel to the surface  28 . 
     If the front member of the cart is tilted upwardly to facilitate the wheeling away of the cart on its rear wheels, the stop dogs on the rear wheels will assist in preventing this by the engagement of the bottom edge  72 ,  82  of the stop dogs with the surface  28 . As the bottom edge  38  is in contact with the surface  28 , the wheel  34  is inhibited from rolling. 
     It is to be understood that the pivotable caster  70 , as shown in FIGS. 1 and 2, is reversed, with the strap or stop dog facing forwardly. The purpose of this is to insure that motion of the cart would be thwarted if, when the front member  14  of the cart is tilted upwardly, a would-be thief instead tried to wheel the cart away in a direction. It is to be further understood that both rear casters on the cart  10  may be fixed casters or rotatable, and further that the rear casters may be one each of fixed and rotatable. 
     While the collapsible front suspension has been shown as collapsing toward the rear of the cart frame, another embodiment of the invention might also have the front suspension collapse toward the front of the cart frame  12 . 
     To reset the release pins  110  and  112  from their retracted positions to their extended positions, a T-shaped tool such as the tool shown in Figure would be used to engage the internally threaded or recessed tamper-proof screw  160  in order to rotate the pivoting member  156  an amount sufficient to cause the release pins to extend beyond the exterior side surfaces  106  and the notch  52  to be reengaged with the side of the pivoting member  156 . 
     The reset tool  200 , shown in FIG. 5, is used to rotate the pivoting member  156 , and comprises a handle  202 , an elongated shank  204  disposed substantially normal to the handle, and a projecting end  206  that is provided with an end portion complimentarily configured to engage in the recess of the screw  155 . For example, if the recess in the screw head is polygonal, the end  206  would bear an external polygonal configuration that complements that of the recess. The handle  202  facilitates turning of the tool  200  once it is engaged in the recess in the screw. 
     Referring now to FIG. 6, the invention contemplates surrounding the perimeter of the area of protection (eg, a parking lot) with a cable or wire  400  that emits a “triggering” signal. Once the shopping cart  10  is pushed past the signal-emitting boundary, the front suspension  24  collapses, thereby disabling the shopping cart. 
     The present invention may be embodied in other specific forms without departing from the spirit or essential attributes. For example, the collapsible front suspension may be retrofitted onto existing shopping carts according to an embodiment of the invention. Moreover, the rear casters on the shopping carts can be interchanged so that the carts can have different types of rear casters or the same type of rear casters. Accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.