RELATED APPLICATIONS This application claims benefit under 35 U. S. C. § 119(e) to U.S. Provisional Application Serial No. 60/598,934, entitled "INCREASED THROUGHPUT INSPECTION STATION," filed on August 5, 2004, which is hereby incorporated by reference in its entirety.

BACKGROUND OF INVENTION 1. Field of Invention The invention relates generally to inspection stations such as those used at airports to screen luggage for explosives or other contraband. This invention relates more specifically to increasing the rate at which items may flow through inspection stations.

2. Discussion of Related Art Inspection stations are often used to screen baggage, such as carry-on baggage, at airports and secure facilities. In some inspection stations, carry-on baggage and other items may be placed on trays, and the trays may be placed on a conveyor belt to be moved through an inspection region. FIG. 1 illustrates an example of an existing inspection station such as may be used at an airport to screen carry-on baggage. Inspection station 100 includes an inspection region 110. In many cases, items in inspection region 110 may be scanned by x-rays using an x-ray line scanning approach. An x-ray line scanner may form an image of objects as they are moved through the inspection region. The image may typically be displayed at a work station 112 for a human operator 114 to observe. Human operator 114 may clear an item and allow it to pass through the inspection station if no suspicious areas appear in the image. If suspicious areas appear in the image, the item may be required to undergo other levels of inspection, e.g., a physical search of the item. Inspection station 100 may include a conveyor 120. Conveyor 120 may be a moving belt propelled by one or more motors, such as motor 302. Conveyor 120 may move items through inspection region 110 in such a way that images of the items can be formed. To contain and/or protect items being passed through inspection region 110, trays, such as 130A, 130B and 130C are often provided at the inspection station. For example, passengers passing through an airport security checkpoint will often place keys, coins and other metal objects in trays to be moved through inspection region 110. Passengers may place cell phones, PDA's and other portable electronic devices in trays, which may enable a more thorough inspection of the items. As a further example, passengers may be required to place coats, shoes, belts or other items of clothing in trays 130 for passing those items through inspection region 110. Typically, a stack of trays is provided at the entry region of the inspection station. Passengers may place their items in a tray 130 and set the tray on conveyor 120, which moves the tray and the items through the inspection region 110 to an exit region on the other end of the inspection station. The trays 130 may accumulate at the exit region until an operator carries them back to the entry point of the inspection station.

SUMMARY OF INVENTION In one aspect of the invention, items are inspected according to a method that includes mechanically conveying trays from an exit region to an entry region of the inspection station. In another aspect, the invention relates to a method of inspecting items. The method includes moving the items on trays from a first region to a second region through an inspection region. The method also includes inspecting the items to detect a presence of contraband. The method further includes mechanically conveying the trays from the second region to the first region. In yet another aspect, the invention relates to an inspection station for detecting a presence of contraband within items. The inspection station includes a first region, a second region, and an inspection region. The inspection station also includes a first conveyance system to convey the items on trays from the first region to the second region through the inspection region. The inspection station further includes a second conveyance system to convey the trays from the second region to the first region. In a further aspect, the invention relates to an inspection station for detecting a presence of contraband within items. The inspection station includes a first region, a second region, and an inspection region. The inspection station also includes a first conveyance system to convey the items on trays from the first region to the second region through the inspection region. The inspection station further includes means for mechanically conveying the trays from the second region to the first region.

BRIEF DESCRIPTION OF DRAWINGS The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

FIG. l is a sketch of a prior art inspection station; FIG. 2 is a side view of an inspection station according to one embodiment of the invention; FIG. 3 is a side view of an inspection station according to an alterative embodiment of the invention; FIG. 4A is a side view of an inspection station according to an alternative embodiment of the invention; and FIG. 4B is a side view of an inspection station according to an alterative embodiment of the invention.

DETAILED DESCRIPTION Inspection stations are often used with trays that may be used for moving items through the inspection station. The inventor has appreciated that it may undesirable for a human operator to carry trays from an exit region near the end of a conveyor back to the entry region of an inspection station. For example, passengers may be required to wait while the human operator carries the trays. It may be a source of frustration for passengers or others required to pass through the inspection station to have to wait for trays to be available at the entry region. As another example, requiring a human operator - A -

of the inspection station to move trays may distract the operator from providing security and ensuring the integrity of the inspection. In one aspect of the invention, the trays may be mechanically conveyed from an exit region to an entry region of an inspection station. The entry region may be the region near the beginning of conveyor 120 where items may be placed on trays 130, and where the trays may be placed on conveyor 120. The exit region may be the region near the end of conveyor 120 where items may be collected. Mechanically conveying the trays may increase the throughput of an inspection station. As used herein, the term mechanically conveying means imparting motion to an object by a mechanical system such that the object is moved from one position to another position. A first embodiment of the invention is illustrated in FIG. 2. Inspection station 200 incorporates a conveyor 220 that may move in the opposite direction of conveyor 120. As trays such as 130A and 130B reach the end of conveyor 120 and items are removed from the trays, the trays can be placed on conveyor 220 that may return the trays to the entry region of the inspection station. Conveyor 220 may be a belt type conveyor similar to conveyors currently used in x-ray inspection stations and may be propelled by one or more motors, such as motor 304. However, any convenient mechanical conveyance means may be used. For example, conveyor 220 may be implemented as a series of rollers placed at an incline such that a tray 130B on conveyor 220 in the exit region of inspection station 200 may slide down conveyor 220 without human interaction. Other possibilities include using a rubberized band, a chain or other system of linkages with a means, such as a hook, to engage a tray. Further it is not necessary that trays such as 130A and 130B rest on conveyor 220. Conveyor 220 may impart motion to a tray such as tray 130B by lifting the tray. For example, a motorized trolley may run on a track and the trolley may include a hook or other attachment mechanism to attach it to a tray 130. FIG. 3 shows an alternative embodiment. Conveyor 120 may be preceded by a non-motorized segment 310 and followed by a non-motorized segment 312. Such non- motorized segments may enable trays to be moved relatively easily to belt 120 or away from belt 120. These non-motorized segments 310 and 312 may include, for example, a series of rollers 314. Trays may easily slide on the rollers, but the speed of the trays on the non-motorized portions need not match the speed of conveyor 120. A similar arrangement may be used on conveyor 220. Conveyor 220 may be motorized, and may be followed by a non-motorized segment 322 that forms a holding area for empty trays. Trays may be pushed by the motion of motorized conveyor 220 to the holding area, e.g., non-motorized segment 322. Trays on conveyor 220 may generally move at a speed dictated by the motor for conveyor 220. However, because non-motorized segment 322 may not be coupled to the motorized segment, e.g., conveyor 220, trays could move through the holding area created by non-motorized segment 322 at a different rate, e.g., a rate dictated by the rate at which the trays were being used to place items through inspection station 300. Other ways to construct a holding area for trays exiting conveyor 220 may also be used in place of or in addition to a non-motorized segment of a belt. For example, a holding area for trays may be created by simply stacking the trays. Generally, trays used in inspection stations may be designed to nest, one inside the other. Trays may be nested simply by allowing them to fall off the end of the conveyor. Alternatively, a robotic arm or some other automated structure could remove trays from the conveyor and stack them in a holding area. FIGs. 4A and 4B illustrate alternative embodiments. Trays traveling on conveyor 220 may usually be empty. Therefore, it is not necessary that trays on conveyor 220 retain the same orientation that they have on conveyor 120. FIG. 4A shows that trays such as 130C, 130D, and 103E are placed on their side such that a narrow dimension of the tray is parallel to conveyor 220. Such a configuration may allow more trays to be held in a holding area, such as non-motorized segment 422. FIG. 4B shows an alternative configuration for the trays on the return conveyor. FIG. 4B shows trays such as 130C and 130D on the return conveyor 220 with a narrow dimension parallel with the width of belt 120. Such a configuration may be desirable when limited space is available under inspection region 110. The desired orientation of the trays may be achieved by providing slots or other features to hold trays in the desired orientation on conveyor 220. As one example, a robotic arm or other mechanical assembly may provide a means for placing the trays on conveyor 220 with the desired orientation. Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. The foregoing are intended to be examples of embodiments of the invention. Various alternatives may be made. For example, it is not necessary that return conveyor 220 be physically separate from conveyor 120. While the upper surface of conveyor 120 carries items from the input of the inspection station to the exit point of the inspection station, the lower surface of conveyor 120 moves in the opposite direction and can be used to propel trays back to the entry point of the inspection station. The trays may be coupled to the underside of belt 120 in any convenient manner such as by hooks or other fasteners. Further, an x-ray line scanner is used as an example of a scanner used to inspect items in an inspection station. A computed tomography system and/or other types of inspection equipment may be used in place of a line scanner. Further, other types of radiation may be used to form images, e.g., gamma rays. Further, it is not necessary that inspection station 100 form images of objects. Other scanning technologies are known that may be employed. For example, inspection regions that detect certain types of chemicals may be used. The inspection station may include several inspection systems. For example, inspection stations used at airports to screen carry-on baggage often include several x-ray scanners arranged in a parallel configuration. Some passengers may have items that are inspected by one x-ray scanner and some passengers may have items that are inspected by a different x-ray scanner. An attendant may, for example, direct a passenger to an x- ray scanner that has the shortest line. In one aspect of the invention, an inspection station may include one means to mechanically convey trays back to an entry region of the inspection station. For example, trays may pass through several different x-ray scanners to an exit region of the inspection station, but may all be mechanically conveyed from the exit region to the entry region on the same conveyor belt. However, any suitable number of means for mechanically conveying trays may be used, e.g., several conveyor belts. As another example, an item may be inspected by multiple inspection systems before reaching an exit region of the inspection station. For example, an item may be scanned by two different types of inspection systems, such as two different types of x-ray scanners (e.g., a line scanner and a CT scanner), or an x-ray scanner and an explosives detection system. In inspection stations where an item is inspected by multiple inspection systems the distance from the exit region to the entry region of the inspection station may be relatively great. It may be disadvantageous for a human operator to carry trays a relatively great distance from the exit region to the entry region. In one aspect of the invention, trays may be mechanically conveyed from the exit region to the entry region. It is not necessary that the inspection station have a human operator as illustrated in FIG. 1. Inspection may be performed through automated threat recognition software on a computer associated with the inspection region, or with some combination of automated software and human review. As another example, the inspection station may have a remote human operator. The remote human operator may be stationed at a remote location such as across the room from the inspection station, in a different room than the inspection station or even in a different building or facility. The remote human operator may perform various tasks that a human operator may often perform while stationed in close proximity to the inspection station, e.g., viewing images of items on a display, identifying threats, and monitoring the inspection station for suspicious activity. Performing such tasks remotely may be enabled by transferring data via a network connection from the inspection station to a remote workstation. Mechanically conveying trays may provide for an environment in which a human operator stationed in close proximity to the inspection station may be replaced with a remote human operator. As a result of the trays being mechanically conveyed, the human operator may not need to be stationed in close proximity to the inspection station to manually carry the trays. Also, "trays" are not limited in shape or size to the examples illustrated. A "tray" may be any component used for support of items moving through an inspection system. This invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having," "containing," "involving," and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only. What is claimed is: