Abstract:
A checkpoint system, wheeled bins for a checkpoint system, and methods for conveying articles in wheeled bins through a checkpoint system. Each bin has four wheels that do not extend below the bin&#39;s flat bottom. In this way, the bin can be slid on its bottom along a shallow, troughed divesting table while it is being filled and conveyed on its bottom through a checkpoint and rolled on its wheels along a deeper troughed discharge lane. A bin return beneath the discharge lane returns bins to a bin storage queue beneath the divesting table. A sorter at the output of the checkpoint selectively diverts bins to one or more discharge lanes, such as individual lanes for cleared and for suspect bin contents.

Description:
BACKGROUND 
     The invention relates generally to checkpoint systems, such as airport security systems, and more particularly to checkpoint systems conveying articles to be checked in bins and methods for operating those systems. 
     Every airline passenger is familiar with airport security checkpoints. The passenger empties his pockets into a plastic bin, drops in his belt and shoes, and adds other items he is carrying. He pushes the loaded bin along a gravity-roller conveyor until the bin reaches a flat conveyor belt, which eventually conveys the bin into an x-ray scanner. After passing successfully through the personnel scanner, the passenger unloads his bin, which has been discharged from the scanner along a declining gravity-roller conveyor. An airport-security worker then collects the unloaded bins, carries them back to a table near the starting point, and stacks them there. If the scanned image of a bin shows suspicious or unidentifiable items, that bin is manually removed from the line of cleared bins and inspected. These manual methods of handling bins are not a productive use of a security worker&#39;s time. 
     SUMMARY 
     These shortcomings and others are overcome by a checkpoint system embodying features of the invention. In one version of such a checkpoint system, articles to be checked are loaded in bins, each of which has a front panel, a rear panel, a left panel, and a right panel upstanding from a bottom panel. The left, right, front, and rear panels form four side walls that extend from the bottom panel upward to a top rim. At least two wheels extend outward of each of the left and right panels. The peripheries of the wheels do not extend below the bottom side of the bin. The bins, loaded with the articles to be checked, are slid on their bottom panels along a divesting table toward a checkpoint. A checkpoint conveyor conveys the bins received from the divesting table through the checkpoint in a conveying direction. At least one discharge lane receives checked bins from the checkpoint conveyor. A discharge lane comprises a pair of parallel rails along which the wheels on the left and right panels of the bins ride. Another aspect of the invention comprises the bin already described. 
     Yet another aspect of the invention provides a method for conveying flat-bottomed, wheeled bins to a checkpoint. The method comprises: (a) sliding bins holding article to be checked on the flat bottoms of the bins along a table toward a checkpoint; (b) conveying the bins received from the table through the checkpoint; and (c) rolling the checked bins along a discharge lane formed by rails along which the wheels of the bins ride. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These features and aspects of the invention, as well as its advantages, are further described in the following description, appended claims, and accompanying drawings, in which: 
         FIG. 1  is a perspective view of a wheeled bin embodying features of the invention; 
         FIG. 2  is a side elevation view of the bin of  FIG. 1 ; 
         FIG. 3  is a perspective view of a security checkpoint system embodying features of the invention, such as the bin of  FIG. 1 ; 
         FIG. 4  is a perspective view of a divesting area of the checkpoint system of  FIG. 3 ; 
         FIG. 5  is a perspective view of a sorter in the checkpoint system of  FIG. 3 ; 
         FIG. 6  is a perspective view of a visioning system for detecting loaded scanned bins and of a bin inverter in the checkpoint system of  FIG. 3 ; and 
         FIG. 7  is a perspective view of the entrance to a vertical bin storage queue in the checkpoint system of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     A bin embodying features of the invention making it useful in a checkpoint system embodying further features of the invention is shown in  FIGS. 1 and 2 . The bin  10  is an open, generally rectangular parallelepipedic container formed by five panels: a front panel  12 , a rear panel  13 , a right panel  14 , a left panel  15 , and a bottom panel  16 , which preferably has a flat bottom  18 . The front, rear, right, and left panels form side walls upstanding from the bottom panel of the bin out to distal ends defining the bin&#39;s top rim  20 . The front and rear panels are preferably shorter in length than the right and left panels. Wheels  22  extend outward from the right and left panels  14 ,  15 . The wheels rotate on axes  24 ,  25  parallel to the bottom panel and generally perpendicular to the right and left panels. The left and right wheels are preferably aligned with each other and closer to the bottom panel  16  than to the top rim  20 . More important, the radius R of the wheels does not exceed the distance D of the wheels&#39; axes from the bottom  18  of the bottom panel  16 . Handles  26  extend outward from the top rim  20  along the front and rear panels  12 ,  13 . Besides serving their conventional purpose, the handles also act as spacers ensuring a gap between bins accumulated in line. The bins are preferably symmetrical about both their major and minor axes so that that the bins are identical when rotated 180°. 
     An airport-security scanning system  28  shown in  FIGS. 3-7  exemplifies a checkpoint system that uses the bins  10  of  FIGS. 1 and 2  and embodies other features of the invention. A passenger first removes a bin  10  from a vertical bin storage queue  30  and places it on a divesting table  32  bottom side down. Then the passenger puts his belongings into the bin. The elongated divesting table  32  has parallel side walls  34  running the length of the table and forming a trough with the table top  36 . The side walls are spaced apart across the table top a distance just greater than the length of the front and rear panels  12 ,  13  of the bins. This ensures that the bins are oriented with the front (or rear) panel leading. The bottoms  18  of the bins rest on the table top  36 . The table&#39;s side walls  34  are short enough in height that the shallow trough they form with the table top is not deep enough for the bins&#39; wheels  22 , elevated as they are slightly above the bottom panel  16 , to contact the tops  35  of the side walls, as illustrated in  FIG. 2 . The passenger pushes the bin, guided by the side walls, along the divesting table to a metering conveyor  38 . 
     The metering conveyor  38 , which may be a belt conveyor with a small-pitch, friction-top belt, such as an Intralox® Series 1100 FFT belt manufactured and sold by Intralox, L.L.C. of Harahan, La., U.S.A., receives one bin at a time from the divesting table  32 . The metering conveyor feeds the bins to a checkpoint conveyor  40  that conveys the bins in a conveying direction  41  through the checkpoint, in this example, an x-ray scanning system  42 . The metering conveyor and the checkpoint conveyor operate at different speeds. The speed of the metering conveyor belt sets the throughput rate. The higher speed of the checkpoint conveyor sets the gap between consecutive bins required by the scanning system. 
     After the loaded bins are scanned in the scanner  42 , the checkpoint conveyor feeds them to a sorter  44  over its near side. The sorter selectively diverts the bins to one of two discharge lanes  46 ,  47  over its opposite side. Although only two discharge lanes are shown, a longer sorter could accommodate any number of lanes. If only one discharge lane is used, the sorter may be eliminated. 
     The sorter in this example uses an Intralox® Series 400 DARB belt  48  with Activated Roller Belt™ actuating rollers as described in U.S. Pat. No. 7,588,137, “Conveyor Belt Having Rollers that Displace Objects,” Matthew L. Fourney, Sep. 15, 2009, incorporated into this description by reference. The sorter conveyor belt  48  advances in a travel direction  50  perpendicular to the main conveying direction  41 . The sorter belt has pairs of stacked rollers  52  arranged to rotate on axes  54  oblique to the sorter belt&#39;s travel direction  50  and to the main conveying direction  41 . When the belt rollers are actuated, the top, article-supporting rollers in each stack rotate in a direction  56  perpendicular to their axes of rotation. Then tangential velocity of the rotating belt roller in contact with the bottoms of the bins has a component equal and opposite to the speed of the sorter in the travel direction. The net velocity of the bins pushed by the activated rollers is directed laterally across the sorter. The net result is that the bins supported on actuated belt rollers move in the main conveying direction  41  to a selected discharge lane perpendicular to the belt&#39;s travel direction  50 . When the belt rollers are not actuated, a bin is transported in the belt&#39;s travel direction  50  until the bin reaches the selected discharge lane. At that time, the roller-actuation system for that lane contacts the bottom rollers of the stack in the sorter belt in front of that lane to translate the bin onto the selected lane. 
     In the example system, two discharge lanes are shown: a cleared lane  46  and a suspect lane  47 . Each lane comprises a bed  56  from which side rails  58  extend upward. The rails are spaced apart across the width of the bed a distance equal to the spacing between the corresponding wheels on the right and left sides of the bin. The rails have a flat top surface  60  on which the wheels  22  ride. The trough formed in each discharge lane is deep enough that the bottom panels of the bins do not contact the bed. The lanes are preferably tilted down but away from the scanner. In this way, the bins roll down the rails on the wheels aided by gravity. Except that the rails on the discharge lanes are taller and are tilted off horizontal, the discharge lanes are identical to the divesting table. The troughs may be made in modular sections  60  that can be cascaded to make longer discharge lanes or divesting tables. 
     The sorter  44  directs bins that pass the screening process to the cleared discharge lane  46  where the passenger may retrieve his belongings. Bins containing suspect articles are diverted off the sorter to the suspect discharge lane  47  where security personnel can scrutinize the contents more carefully. In the event of a system failure, the sorter could divert all bins to the suspect lane  47 . 
     At the end of the cleared discharge lane, the bins are individually visioned by a visioning system  62 . Two laser line projectors  64  mounted on a framework  66  above the end of the cleared discharge lane each shine a line  67  across the lane at the intersection of their beams  69  as a camera  68  mounted on the framework monitors the lane from above. Any articles remaining in the bins disrupt the laser beams and cause the line to fragment. The disruption is then detected by the cameras, and a stop  70 , such as a pivoting or vertical stop, is actuated to block the non-empty bin from entering a bin inverter  72  at the start of a bin return  74 . 
     The bin inverter  72  automatically guides empty bins  10  from the cleared discharge lane  46  through a 180° turn along a semicircular path from the end of the discharge lane to a horizontal conveyor  76  directly below the cleared lane  46 . The bin inverter uses a pair of parallel curved tracks  78  that lead from the pair of parallel side rails  58  of the cleared discharge lane to a pair of parallel narrow conveyor belts  80  constituting the horizontal conveyor  76 . The curved tracks, which may be made of U-shaped channel bent to form generally semicircular guides, receive the wheels of the bin from the cleared lane and guide the bin to the horizontal conveyor upside down. Any articles missed by the visioning system and remaining in the bin fall out as the bin is inverted and land on a pad  82  below the bin inverter to be retrieved by airport personnel. 
     A fixed stop  84  at the downstream end of the suspect discharge lane  47  blocks bins from falling off the end of the lane. If a visioning system is not used, the stop at the end of the cleared lane may be a fixed stop like the stop  84  at the end of the suspect lane or a slight bump to prevent the cleared bins from automatically entering the bin inverter. The slight bump is preferably as short as possible to make it easy to remove a bin from the lane but tall enough to stop the bin. The passenger or security personnel can manually load the bins into the bin inverter through flared, open distal ends  88  on a branch  86  of the guide tracks that receive the wheels  22  of bins  10  manually inserted into the bin inverter. In an all-manual bin inverter, the upper portion  89  of the guide tracks leading from the cleared discharge lane may be eliminated. 
     In the bin return, the bin wheels  22  sit atop the two conveyor belts  80 , which advance below the cleared discharge lane  46  and the checkpoint  42  opposite the conveying direction  41  of the checkpoint conveyor  40 . Thus, on the horizontal conveyor, the bins, supported on their wheels, are conveyed upside down back toward the divesting table. 
     An incline conveyor  90 , such as a friction-top belt conveyor, lifts the bins from the level of the horizontal conveyor  76  up to the level of a pair of narrow conveyor belts  92  forming the vertical bin storage queue  30 . Two rotating flappers  94  at the upper ends of side rails  96 , when rotated clockwise to close the gap  98  between the incline conveyor and the bin storage belts, guide the leading portion of each bin onto the vertical bin storage queue. When the trailing end of the bin has cleared the incline conveyor, the flappers drop to the position shown in  FIG. 7  to allow the trailing end of the bin to fall into a vertical position suspended by one pair of wheels from the parallel belts  92 . The belts convey the vertically suspended bins directly below the divesting table  32  back to just in front of the start of the table where the bins may be removed by the passengers. Barriers  98  at end of the vertical bin storage conveyor block the bins from falling off the end. The bins accumulate in the queue with low back pressure because the wheels of the accumulated bins merely roll in place on the continuously running storage belts. 
     The automated portions of the checkpoint system, such as the visioning system, the automated stop, the flappers, the sorter, and the metering and checkpoint conveyors are controlled by a conventional controller, such as a programmable-logic controller, personal computer, work station computer, or other logic device. 
     Although the invention has been described with reference to a preferred version, one skilled in the art will recognize that many alternative versions may be made without departing from the invention as defined in the following claims.