Patent Publication Number: US-2021188577-A1

Title: Feeder for feeding document to document imaging system and method for feeding documents

Description:
Priority Claim 
     This application is a continuation of co-pending U.S. patent application Ser. No. 15/830,840 filed on Dec. 4, 2017, which is a continuation of U.S. patent application Ser. No. 14/751,357 filed on Jun. 26, 2015, now issued as U.S. Pat. No. 9,932,184, which is a divisional application of U.S. application Ser. No. 13/090,172 filed Apr. 19, 2011, now issued as U.S. Pat. No. 9,079,730, which claims priority to U.S. Provisional Patent Application No. 61/325,790, filed Apr. 19, 2010. The entire disclosure of each of the foregoing applications is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of document processing. In particular the present application relates to feeding documents to a device for further processing of the documents. The present invention finds particular application to the field of document imaging in which documents are to be fed to an imaging system, such as a document scanner. 
     BACKGROUND 
     Automated and semi-automated machines have been employed for processing documents. Further, in many instances it is desirable to obtain image data of the documents. However, often the documents are obtained in packets so that the individual documents in a packet need to be separated to be scanned. Although advances have been made in the processing of such packets, an improved system for feeding packets with minimal manual preparation is desirable. 
     SUMMARY OF THE INVENTION 
     In light of the foregoing, an apparatus is provided for improving the semi-automated processing of packets of documents. The apparatus includes a feeder operable to receive a packet of a plurality of documents and separate the documents to serially feed the documents away from the feeder. The apparatus further includes a retard pad adjacent the feeder operable in a first position and a second position, wherein in the first position the feeder forms a nip with the feeder so that the retard is operable to impede the progress of one or more documents in a packet while the feeder feeds one of the documents in the packet. In the second position, the retard is spaced apart from the feeder to form a gap between the feeder and the retard; A sensor is provided for detecting a characteristic of the documents in the packet indicative of whether the number of documents in the packet exceeds a predetermined threshold. A drive mechanism automatically drives the retard pad between the first and second positions in response to the detected characteristic. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The foregoing summary and the following detailed description of the preferred embodiments of the present invention will be best understood when read in conjunction with the appended drawings, in which: 
         FIG. 1  is a perspective view of a document processing system; 
         FIG. 2  is an enlarged fragmentary perspective view of a portion of the document processing system of  FIG. 1 , illustrating features of an image entry feeder module; 
         FIG. 3  is a rear fragmentary perspective view of the image entry feeder module illustrated in  FIG. 2 ; 
         FIG. 4  is a rear fragmentary perspective view of the image entry feeder module illustrated in  FIG. 3 , showing a feeder of the image entry feeder module pivoted upwardly; 
         FIG. 5  is an enlarged fragmentary rearward view of the image entry feeder module of  FIG. 2 ; 
         FIG. 6  is an enlarged fragmentary rearward view of the image entry feeder module of  FIG. 5 , showing a retard assembly pivoted away from the feeder; 
         FIG. 7  is an enlarged perspective view of the image entry feeder module of  FIG. 3  including a cover on which the documents are supported as the documents pass through the image entry feeder module; and 
         FIG. 8  is an enlarged fragmentary perspective view of a portion of the image entry feeder module illustrated in  FIG. 4 , showing enlarged features of the retard assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the figures in general and to  FIG. 1  in particular, a document processing workstation  10  is illustrated. The workstation  10  processes mail by severing one or more edges of each envelope in a stack of mail and presenting the edge-severed envelopes one at the time to an operator who removes the documents from the envelope by hand. The operator can then drop the extracted documents individually or in stacks onto a conveyor that conveys the documents to an imaging station. The imaging station separates the documents, serially feeding the documents to an imager that obtains image data for the documents. The documents are then sorted into one or more output bins. 
     The present system is directed to improving the flow of documents in a document processing system. The system has particular application to workstations directed to processing documents and has particular application to processing packets of documents to scan the documents to obtain image data. In an exemplary embodiment, the workstation is configured as a semi-automated system for processing mail in the form of documents contained within envelopes. However, it should be understood that several aspects of the present system have application to systems that do not incorporate document extraction features, but are instead directed to processing documents generally. For instance, in the following description, an exemplary embodiment includes stations for cutting open envelopes and opening the envelopes so that the user can manually extract the documents. The system further includes a horizontal conveyor onto which the documents are dropped and then conveyed to a scanning station. From the scanning station, the documents are conveyed to a sorting station. Although the various stations are described in the exemplary embodiment, the present system is not limited to such an embodiment. For instance, features of the present system may be incorporated into a system that does not include the extraction features, but includes the horizontal conveyor, scanning station and sorting station. Further still, features of the system may have application generally in a document processing system in which it is desirable to manually feed packets of documents into the system without organizing or otherwise preparing the packets for feeding into the system. 
     Brief Overview 
     With the foregoing in mind, a general overview of the flow of documents in an exemplary system for processing mail is as follows. Initially, a stack of envelopes containing documents, referred to as a job, is placed into an input bin. A feeder  30  removes the lead envelope  5  from the front of the stack and transfers the envelope to a feed tray. 
     The envelope  5  in the feed tray is edge-justified by a plurality of opposing rollers. From the feed tray, the envelope  5  drops into a side cutter, which severs the side edge of the envelope if desired. From the side cutter, the envelope drops into a shuttle. The shuttle moves vertically to adjust the height of the top edge of the envelope to account for variations in the height of the different envelopes in the job. The shuttle moves vertically until the height of the top edge of the envelope  5  is within an acceptable range for advancing the envelope into a top cutter. The envelope is then transported to the top cutter, which severs the top edge of the envelope  5 . 
     From the top cutter the envelope is advanced to an extraction station  70 . The extraction station  70  pulls apart the front and back faces of the envelope to present the contents of the envelope for removal. An operator then manually removes the contents from the envelope  5 . 
     After the operator removes the documents from the envelope  5 , the apparatus  10  automatically advances the envelope to a verifier  90 . The verifier  90  verifies that all of the documents were removed from the envelope before the envelope is discarded. From the verifier  90  the envelope is conveyed into a waste container. Alternatively, the envelope  5  may be manually removed and imaged at the imaging station  210 . 
     After the documents are extracted at the extraction station, the operator unfolds as needed and drops or places the extracted documents onto a drop conveyor  100  that transports the documents toward an imaging station  210 . An imaging entry feeder  110  receives the documents from the drop conveyor  100  and controls the feeding of the documents into the imaging station  210 . The image entry feeder  110  is configured to receive and feed documents of various sizes and condition. For instance, frequently documents are folded in an envelope. When the documents are extracted and opened up, the documents are creased or folded so that they do not lie flat. The feeder  110  is preferably configured to receive such creased or folded documents and serially feed the folded documents into the imaging station  210  with minimal manual preparation by the operator. 
     The imaging station  210  includes an imager  230  that obtains image data for each document as the document is conveyed past the device. For instance, preferably the imager  230  is a scanner that obtains gray scale or color image data representing an image of each document. The scanner scans each document at a plurality of points as the document is conveyed past the scanner. The information for each document is stored in a data file for each document so that the image data can be accessed at a later time. 
     From the imaging device, preferably an imaging transport conveys the documents to a sorting station  240  that sorts the documents into a plurality of output bins  245 . The documents can be sorted in a variety of ways. For instance, the documents can be sorted based on document information obtained from the image data received at the imaging station  210 . Alternatively, the operator may indicate information regarding a document before it is scanned, so that the document is sorted according to the information indicated by the operator. Yet another alternative is that the documents may be stacked into one or more bins simply based on the order in which the documents are processed. 
     Since many of the documents may be creased, ordinarily the documents will not readily stack in a compact manner so that relatively fewer creased documents can be discharged into a bin before the bin is full. Accordingly, the documents may be processed by an uncreaser, which is an element that reduces the creasing or folds in the documents. The uncreaser flattens or straightens the documents so that they lay more flatly in the output bins so that more documents can be discharged into a bin before the bin is full. 
     A controller controls the processing of the mail in response to signals received from various sensors at various locations of the workstation  10  and in response to parameters set for the job by the operator. For instance, in response to an indication from a sensor in the feed tray that there is no envelope in the feed tray, the controller sends a signal to the feeder envelope  30  indicating that an envelope should be fed from the input bin to the feed tray. Similarly, in response to an indication from a sensor in the shuttle that there is no envelope in the shuttle, the controller sends a signal to the feed tray indicating that an envelope should be dropped from the feed tray into the shuttle. 
     The workstation is divided into numerous functionally separate sections, which include: a feeding station  30 , a side cutting station, a top cutting station, the extraction station  70 , the verification station  90 , the imaging station  110 , and the sorting station  240 . In most cases, the controller controls the operation of the various sections independently from each other. This independence allows several operations to proceed simultaneously or asynchronously as required. As a result, a slow down in one section does not necessarily slow down all of the other sections. 
     In addition, preferably the operations of the apparatus from the drop conveyor through the sorting station are controlled separately from the operation of the other stations. Further, preferably, an operator interface is provided so that the operator can intervene to control the processing of the documents. Specifically, preferably a touch screen display  20  is provided that allows the operator to enter various information regarding the documents. 
     Configuration of the Work Station 
     As can be seen in  FIG. 1 , preferably the workstation  10  is configured so that an operator working at the workstation has ready access to each working area. A seating area  15  at the front of the apparatus is centrally located, and the different stations are disposed around the seating area with the paper path flowing in a manner that the documents remain within easy access of the operator at the seating area. 
     Specifically, preferably, the feeding station  30  is disposed adjacent the right side, however, the feeding station can be located on the left side if desired. From the feeding station  30 , the mail pieces are fed along a document path that extends across the workstation along the width of the workstation. Preferably, the extraction station is substantially aligned with the seating area  15  relative to the right and left edges of the workstation so that the operator can readily grasp the mail at the extractor during operation. For instance, preferably the extraction station is generally centered between the right and left edges of the workstation. 
     The drop conveyor  100  is preferably located adjacent the front edge of the workstation and is disposed between the extraction station  70  and the seating area  15  so that the operator reaches over a portion of the drop conveyor to grasp documents at the extraction station. More specifically, preferably a portion of the drop conveyor  100  is disposed adjacent the seating area  15  at the front edge of the workstation. In this way, the operator can readily view, unfold and drop documents from the extraction station  70  onto the drop conveyor  100  when pulling the documents back toward himself/herself. 
     The drop conveyor  100  conveys the dropped documents away from adjacent the seating area  15 , along a path that is generally parallel to the front edge of the workstation. Preferably the document path from the imaging station  210  to the output bins  245  returns toward the seating area. In this way, the output bins  245  are disposed conveniently near the operator at the seating area, so that the operator can readily remove processed documents from the output bins while the operator is at the seating area. 
     Details of the Stations 
     Feeding and Edge Cutting Stations 
     The feeding station  30  includes an input bin and a feeder. The input bin is configured to receive a stack of mail and convey it to the feeder. The feeder comprises a pivoting arm with a suction cup that grasps an envelope from the stack of mail and transports the piece to a side cutting station. In this way, the feeder serially feeds mail from the stack of mail. 
     The side cutting station includes a plurality of drive rollers and opposing idler rollers. As the envelope passes between the rollers a rotary knife severs the side edge of the envelope. The severed edge drops down a scrap chute into a waste container. 
     From the side cutting station, the envelopes are top edge-justified so that the top edge remains at a consistent height. The envelopes may be justified by a pair of rollers to drive the envelopes upwardly against a stop at a predetermined height. However, such a roller justifier is typically limited to justifying envelopes that are similar in height. If there is too much variation among the envelopes in a batch of mail the justifier may not be able to properly justify the envelopes. For instance, if an envelope in a batch is unusually high, the top edge of the envelope may be positioned too high as it enters the justifier so that it causes a jam. If the envelope is unusually low, the top edge of the envelope may not engage the justifier rollers so that the envelope is not justified. 
     Accordingly, in order to accommodate a variety of envelopes, preferably the apparatus includes a shuttle that moves up and down to position the top edge of each envelope at approximately the proper height. The envelopes then enter the top-edge justifier to justify the top edge of the envelopes. The shuttle is a bin that receives each envelope and moves up or down as necessary to adjust the height of the top edge of each envelope as necessary depending upon the height of each envelope. 
     After the envelopes are top edge-justified, the envelopes are conveyed to a top cutting station that severs the top edge of the envelopes. In this way, the top and leading edge of each envelope is cut by the two cutting stations. Optionally, the side cutting station can be configured so that both sides of each envelope is severed. Yet another option is to eliminate or disable the side cutters so that only the top edge of the envelopes is opened. 
     Extraction Station 
     The extraction station  70  operates to pull apart the faces of the edge-severed envelopes and present the contents so that an operator can easily remove the documents. After the operator removes the contents, a sensor sends a signal to the controller that the contents have been extracted. The empty envelope is then transported to the verification station  90  and another envelope is fed to the extraction station  70 . 
     Referring now to  FIG. 9 , the extraction station  70  includes a pair of opposing vacuum suction cups mounted on two pivotal extractor arms. The suction cups are connected to a vacuum pump. In the first position, the extractor arms are pivoted away from one another. In the second position the extractor arms are pivoted toward one another. 
     As shown in  FIG. 1  the extraction station  70  is positioned in front of the seating area  15  intermediate the front and rear edges of the workstation. Before an envelope enters the extraction station, the extractor arms are pivoted away from one another. When the envelope enters the extractor, the arms pivot toward one another and negative pressure is supplied to the suction cups so that the suction cups engage the faces of the envelope. The arms then pivot away from one another pulling apart the faces of the envelope, which have been severed along the top edge and preferably the side edge. The operator can then remove the contents of the envelope. 
     The document transport pinches the envelope between idler rollers and a belt. Therefore, when the extractor arms pull apart the faces of the envelope, the envelope and its contents remain pinched between the idler rollers and the belt. To remove the contents, the operator pulls the contents with enough force to overcome the friction between the envelope and the contents caused by the pinching action of the extraction transport. In addition, this friction is maintained until the bottom edge of the contents is pulled past the pinch point. 
     Verification Station 
     The verification station  90  checks the thickness of each envelope to ensure that all of the contents have been removed from the envelope before the envelope is discarded into the waste container. The verifier  90  can use an optical sensor to check the thickness of the envelope, similar to the optical sensor or sensors used by the extraction station  70 . However, the verifier preferably checks the thickness of the envelope by measuring the distance between the outer surfaces of the envelope faces. To measure this distance, the verifier  90  includes a rotary variable inductive transducer (RVIT). 
     If the verifier  90  measures a thickness that is greater than the reference value, then a signal is sent to the controller indicating that the envelope in the verifier  90  is not empty. An indicator light (not shown) is lit indicating to the operator that the envelope at the verifier should be removed and checked to ensure that all of the contents were removed. A verifier sensor adjacent the RVIT sensor detects the presence of the envelope in the verifier  90 . Until the operator removes the envelope from the verifier, the document transport will not advance any envelopes, regardless of whether the envelope in the extraction station  70  is empty. 
     If the verifier  90  detects a thickness that is less than the reference value, a signal is sent to the controller indicating that the envelope at the verifier is empty. The controller then activates the document transport to advance the envelope out of the extractor and into a trash chute that discards the envelope into the waste container beneath the verifier  90 . 
     The operation of the feeding station  30 , side and top cutting stations and extraction station  70  are similar to the operation of the apparatus described in U.S. Pat. No. 7,537,203, which is owned by Opex Corporation, who is also the assignee of the present patent application. U.S. Pat. No. 7,537,203 is hereby incorporated herein by reference. In addition, alternative feeding and cutting stations could be incorporated into the present apparatus. 
     The following description discusses the processing and imaging of documents that have been extracted from opened envelopes in the manner discussed above. However, in certain applications, the apparatus is operable to process documents without using the extraction features of the apparatus. For instance, the apparatus may be used to process a batch of documents that have been previously extracted, such as documents that are rejected by high speed automated processing devices. For such documents it is advantageous to use the feeding and scanning features as discussed below. Similarly, a batch of pre-slit mail may be processed, whereby the operator manually opens the slit envelopes and then processes the documents as discussed further below. Accordingly, unless otherwise noted below, the following discussion of the document imaging process is applicable to a variety of applications in which a batch of documents needs to be imaged, without regard to how the documents are obtained (i.e. the documents are provided in a stack as opposed to documents that must be extracted from envelopes). Features of the present invention are not limited to applications in which system includes the envelope opening and extraction features discussed above. 
     Drop Conveyor 
     Referring to  FIG. 1 , the drop conveyor  100  is configured to receive documents extracted from the envelopes. The conveyor  100  is disposed along the front edge of the workstation  10 , such that the conveyor is operable to convey documents adjacent to and parallel to the front edge of the workstation. In addition, the conveyor preferably conveys the dropped documents toward the left hand side of the workstation from the perspective of  FIG. 1 . 
     Preferably the conveyor  100  is configured to readily receive documents that the operator manually removes from an envelope at the extractor. More specifically, the conveyor is configured to receive documents that are simply dropped onto the conveyor and then convey the dropped documents to the imaging station  210 . In this way, the operator can readily extract and, if necessary, unfold documents and simply drop a document or packet of documents onto the conveyor with minimal preprocessing of the documents to prepare the documents for scanning. 
     Although the operator preferably drops the documents onto the drop zone of the conveyor, the drop zone is a substantial area that is much larger than the documents. Accordingly, the operator does not need to be precise with the location and orientation that the documents are dropped onto on the conveyor. However, preferably the operator drops the documents so that the documents are front face up on the conveyor. 
     To this end, preferably the conveyor  100  is a roller bed conveyor. The bed of rollers provides a generally horizontal surface onto which documents can be dropped. The roller bed comprises a plurality of horizontally disposed cylindrical rollers driven by a belt engaging the bottom of the rollers, which in turn is driven by a motor controlled by the system controller. The rollers  102  may be parallel to each other and perpendicular to the direction of travel so that the documents move straight along the roller bed  100 . However, preferably, the rollers are skewed so that the rollers drive the documents forwardly along the roller bed and laterally toward a justification rail  105 . In this way, the skewed rollers  102  drive the documents against the rail  105  to edge-align or justify an edge of the documents against the rail. 
     Each of the rollers  102  comprises a plurality of grooves sized to receive O-rings. The O-rings have a higher coefficient of friction than the surface of the rollers, to provide an area of increased friction between the roller bed and the documents, thereby improving the justification of the documents. As mentioned previously, the document rests on the rollers. Therefore, as the rollers  102  rotate, the rollers move the documents forwardly. 
     Although, the drop conveyor  100  has been described as a roller bed conveyor, alternative types of conveyors can be utilized as the drop conveyor. For instance, the drop conveyor may comprise a horizontal conveyor belt. If a conveyor belt is used, preferably the belt is skewed toward the rail  105  so that the belt justifies the documents against the rail. Alternatively, rather than a single conveyor belt, the drop conveyor may comprise a plurality of smaller conveyor belts onto which the documents may be dropped. 
     Although the conveyor  100  is referred to as a horizontal conveyor, preferably the drop conveyor is angled downwardly so that gravity urges the documents toward the guide rail  105 . Preferably the conveyor  100  is angled at approximately five degrees, however, the angle may be higher, and in fact, the angle of the conveyor may be increased to a point that the conveyor is vertical rather than horizontal. In addition, preferably the imaging station and sorting station are angled downwardly similarly to the drop conveyor. 
     Image Entry Feeder 
     Referring to  FIGS. 2-8  the details of the image entry feeder  110  will be described in greater detail. The image entry feeder is position adjacent the end of the drop conveyor  110 , so that the drop feeder conveys the documents to the image entry feeder, which in turn feeds the documents to the imaging station  210 . As the documents are conveyed to the image entry feeder  110 , the documents are generally horizontally disposed, riding on top of the drop conveyor  100  and are edge-aligned against the justification rail  105 . 
     The image entry feeder  110  is operable to serially feed documents from the drop conveyor  100  to the imaging station  210  so that the documents can be individually imaged. The image entry feeder  110  is operable to receive a number of different types of documents, including individual documents, envelopes, and packets of envelopes. In the following discussion, a packet of documents should be understood to mean a group of two or more documents that are in overlapping relation, as opposed to a number of documents that may be related, but which are conveyed serially to the image entry feeder. 
     When processing packets, the image entry feeder  110  separates and serially feeds each document in a packet to the imaging station  210 . The image entry feeder  110  includes a pre-feeder assembly  120  and a feeder  160 . The pre-feeder assembly  120  is configured to prepare packets for entry into the feeder  160 , thereby reducing the likelihood of a jam occurring as a packet enters or is processed by the feeder. 
     The pre-feeder assembly  120  comprises a pair of pre-feeders: a first pre-feeder assembly  122 , which the documents first engage when they enter the pre-feeder assembly from the drop conveyor  100 , and a second pre-feeder  124  configured similar to the first pre-feeder. The second pre-feeder  124  receives the documents from the first pre-feeder  122  and feeds the documents to the feeder  160 . 
     Referring to  FIGS. 2,3 and 5 , the first pre-feeder assembly  122  includes a pair of opposing rollers  128  and  130  that form a nip. An angled guide  115  at the end of the justification rail  105  overhangs the conveyor  100  and directs the documents downwardly toward the nip of the first pre-feeder assembly  122 . More specifically, for folded documents that were unfolded but remained creased, or documents that are otherwise not flat, an upper edge of the documents tends to be spaced up off of the surface of the drop conveyor. The justification rail  105  has a lip overhanging the drop conveyor  100 , so that this upper edge of the documents tends to be displaced under the lip of the justification rail as the conveyor tends to move the documents toward the justification rail. The angled guide  115  interacts with the justification rail, so that the upper edge of the folded documents is flattened downwardly toward the conveyor so that the leading edge of the document can enter the nip of the first pre-feeder assembly rather than folding over. 
     As mentioned above, the first pre-feeder assembly includes an upper roller  128  and a lower roller  130 . The upper roller  128  is a drive roller, and the lower roller  130  is a driven roller. The upper roller  128  is mounted on a pivoting arm  134  that pivots about a pivot shaft  135 . A biasing element biases the pivot shaft to urge the upper roller  128  toward the lower roller  130 . As documents enter the first pre-feeder assembly  122 , the roller and pivoting arm pivot away from the lower roller against the bias of the biasing element to form a gap large enough to accommodate the document or packet of documents entering the first pre-feeder assembly. As the trailing end of the document or packet of documents exits the first pre-feeder assembly  122 , the upper roller  128  pivots into engagement with the driven roller  130  until the subsequent document or packet enters the first pre-feeder assembly. 
     As discussed further below, it may be desirable to incorporate a thickness detector  138  into the first pre-feeder assembly  122 . The thickness detector may be any of a variety of sensors, such as an LVDT sensor or RVIT sensor. However, preferably the thickness sensor  138  is a Hall effect sensor. The Hall effect sensor includes a sensor board disposed adjacent a magnet that is mounted on the pivot arm 134  that biases the magnet toward the sensor. The magnetic field created by the magnet is measured by the sensor board as a function of the distance between the magnet and sensor. When a document or packet enters the thickness detector  138 , the pivot arm  134  is forced apart, thereby separating the magnet and the sensor board accordingly, changing the magnetic field intensity, thereby indicating the thickness of the document(s) in the first pre-feed assembly. 
     The lower roller  130  of the first pre-feeder  122  is rotatably mounted on a fixed shaft and may operate simply as an idler roller. In the present instance, the lower roller is coupled to the fixed shaft via a torque limiting device  132 . A variety of torque limiting devices can be utilized, and in the present instance, the lower roller is connected with the shaft via a magnetic torque limiter, the operation of the torque limiting element will be described further below in greater detail. 
     From the first pre-feeder assembly  122 , the documents enter the second pre-feeder assembly  124 . The structure of the second pre-feeder assembly is substantially similar to the first pre-feeder assembly, including a pivoting upper roller forming a nip with a lower roller mounted on a fixed shaft via a torque limiting element. However, in the present instance, the second pre-feeder assembly  124  does not include a thickness detector for detecting the displacement of the pivoting arm on which the upper roller is mounted, as may be incorporated in the first pre-feed assembly  122 , as discussed above. 
     As shown in  FIG. 3 , a thickness detector  150  is positioned between the first pre-feeder assembly  122  and the second pre-feeder assembly  124 . The thickness detector is operable to provide indicia of the number of documents being conveyed from the first pre-feeder assembly  122  to the second pre-feeder assembly. In one manner, the thickness detector may determine the thickness of the document or packet of documents and then estimates the number of documents based on the assumed thickness for an individual document. However, in the present instance, the thickness detector  150  does not directly measure the thickness of the document or packet. Instead, the thickness detector  150  is an ultrasonic detector that uses ultrasound waves emitted from a transmitter and received by a receiver. Based on the signals received by the receiver, the number of transitions between sheets of papers can be determined to evaluate how many documents are in a stack. 
     In addition to the thickness detector, a pre-feed sensor  152  is also provided, which senses the leading edge of a document or packet as the document or packet is conveyed through the pre-feeder assembly  120 . The pre-feed sensor  152  may be any of a variety of sensors, and the functionality of the pre-feed sensor may be combined with the functionality of the thickness detector  150 . However, in the present instance, the pre-feed sensor  152  is a separate sensor in the form of an infrared transmitter and receiver disposed between the first pre-feed assembly and the second pre-feed assembly. More specifically, the pre-feed sensor  152  is mounted on the circuit board on which the ultra-sound detector  150  is mounted, which is disposed between the first pre-feed assembly  122  and the second pre-feed assembly  124 . 
     From the second pre-feeder assembly  124 , the documents enter the feeder  160 . If a packet of documents is fed through the pre-feeder assembly  120 , the feeder operates to singulate the documents in the packet so that each document is serially fed into the imaging station  210 . If instead of a packet, a single document is fed through the pre-feeder assembly  120 , the single document simply passes through the pre-feeder and is fed by the feeder  160  to the imaging station  210 . 
     The feeder  160  includes a plurality of feedbelts  165  spaced apart from one another across the width of the image entry feeder module  110 . Although a single wide belt could be used, in the present instance, the feeder incorporates parallel belts mounted about a plurality of rollers. Specifically, in the present instance, the feeder  160  includes a drive roller  162  mounted on a drive shaft  161 . The feedbelts  165  are also entrained about a pair of driven rollers  164  as shown in  FIG. 5 . The rollers  162 ,  164  are rotatably mounted between a pair of mounting brackets  167 ,  168 . The front mounting bracket  167  is a flat arm as shown in  FIG. 5 ., however, the rear mounting bracket  168  includes an attached lifting arm for pivoting the feeder as discussed further below. 
     The feeder  160  is driven by drive shaft  161  and is also pivotable about the drive shaft. For instance, in  FIG. 3  the feeder  160  is pivoted downwardly into an operation position in which the feeder can feed documents. In  FIG. 4 , the feeder  160  is pivoted upwardly to allow removal of documents that may be jammed in the feeder. 
     A retard mechanism  180  is disposed opposing the feeder  160  to selectively impede the entrance of documents into the feeder  160 . Additionally, a nip is formed between the feeder  160  and a pair of spring-mounted idler rollers  170  that are biased toward the feeder. In this way, documents entering the feeder pass between the spring-mounted idler rollers  170  and the feed belt. 
     The retard mechanism  180  selectively cooperates with the feed belts  165  to separate the documents in a packet. Referring to  FIG. 8 , the details of the retard assembly are enlarged. An angled ramp guides documents exiting the nip of the second pre-feeder assembly  124  and directs the documents toward the area between the feeder belts  165  and the retard assembly  180 . The retard mechanism  180  includes a high friction retard pad  182  so that the frictional force between a document and the retard pad is greater than the frictional force between two documents. The retard pad can be formed in any of a number of configurations. However, in the present instance, preferably the retard pad has a plurality of spaced apart ridges that are disposed between the belts that form the feeder. The retard pad  182  is mounted on a mounting frame  184  and the upstream end of the frame  184  is pivotable about pivot shaft  185 . 
     The retard mechanism  180  selectively cooperates with the feed belts  165  to separate the documents in a packet. Referring to  FIG. 8 , the details of the retard assembly are enlarged. An angled ramp guides documents exiting the nip of the second pre-feeder assembly  124  and directs the documents toward the area between the feeder belts  165  and the retard assembly  180 . The retard mechanism  180  includes a high friction retard pad  182  mounted on a mounting frame  184 . The upstream end of the frame  184  is pivotable about pivot shaft  185 . 
     The frame  184  pivots between an upper position (see  FIG. 5 ) in which the retard pad  182  is adjacent to or in contact with the feed belts  165 , and a lower position (see  FIG. 6 ) in which the retard pad is displaced away from the feed belts to create a distinct gap between the retard pad and the feed belts. A rotatable cam  188  operatively linked with the mounting frame  184  of the retard  180  is operable to displace the mounting frame, and therefore, the retard pad, between the upper and lower positions. The operation of the retard assembly  180  will be described below in greater detail. 
     Referring to  FIGS. 2-3, 5 and 7 , the drive control of the image entry feeder  110  will be described in greater detail. A drive motor  190  (see  FIG. 5 ) drives the image entry feeder module  110 . As shown in  FIG. 2 , the motor  190  is connected with a drive pulley  192 . The drive pulley  192  is interconnected with a feed belt drive pulley  194  by a drive belt. The feed belt pulley  192  drives the drive shaft  161  of the feeder  160 . Additionally, as shown in  FIG. 7 , the transfer belt  195  interconnected with the drive shaft  161  drives transfer pulley  196 . Transfer pulley  196  drives the shaft that drives pre-feed drive pulley  197 , which in turn drives second pre-feed belt  199  and first pre-feed belt  198 . The first pre-feed belt  198  drives the driven roller of first pre-feed assembly  122 . Similarly, the second pre-feed belt  199  drives the driven roller of the second pre-feed assembly. 
     Referring still to  FIG. 2 , a braking mechanism  140  is illustrated. The braking mechanism  140  is operable to brake the first and second pre-feeed assemblies  122 ,  124 . Specifically, brake  140  is interconnected with the lower roller of the first pre-feed assembly  122  via gears. Similarly, brake  140  is interconnected with the lower roller of the second pre-feed assembly  124  via gears. In this way, when the brake  140  is actuated, the gears transmit a braking force to the lower rollers  130  of the pre-feed assemblies  122 ,  124 . 
     Referring to  FIGS. 2 and 5  the drive mechanism for the retard cam  188  is illustrated. The drive mechanism includes a dc motor  189  (see  FIG. 5 ), which drives a drive belt  191  via a pulley (see  FIG. 2 ). The belt  191  drives the rotatable shaft onto which the cam  188  is mounted, as shown in  FIG. 5 . 
     In the foregoing description, the drive mechanisms between the motors  189 ,  190  include a plurality of belts and pulleys. Although a variety of belts and pulleys can be used to transmit power between the motors  189 ,  190  and the various elements, in the present instance, the belts are timing belts and the pulleys are timing pulleys, as illustrated in the Figures. Additionally, it may be desirable to utilize different drive elements to transfer the power from the motors to the driven elements. For instance, rather than drive belts, the system may utilize a series of gears to interconnect the motors with the driven elements. 
     In addition to the elements described above, the flow of documents through the image entry feeder module  110  may also be controlled based on signals received from sensors in the imaging station  210 . For instance, referring to  FIGS. 3-4 , the imaging station  210  includes a feeder exit sensor  215  positioned downstream from the feeder  160 , but upstream of crusher rollers  220  that engage the documents to control the transport of the documents through the imaging station  210 . The feeder exit sensor  215  may be any of a variety of sensors that are operable to detect the leading and/or trailing edge of a document. In the present instance, the image entry sensor  215  is an infrared transmitter/receiver sensor. 
     Additionally, the imaging station  210  may include a sensor  227  that detects the leading edge of documents downstream from the crusher roller prior to the documents entering the imager. At this point, the documents are entrained by the crusher roller  220  and no longer controlled by the image entry feeder module  110 . The sensor  227  may also be operable to detect the thickness profile of a document. The thickness profile can then be evaluated to determine a characteristic about the document. For instance, the profile for two documents as detected by the ultrasound sensor  150  is similar to the profile for an envelope. However, the thickness profile for an envelope has characteristics that distinguish the envelope from two sheets of paper due to the changes in thickness over the length of the envelope resulting from the seams of the envelope. 
     Configured as described above, the image entry feeder module  110  operates as follows. The drop conveyor  100  conveys one or more documents to the image entry feeder module  110  to feed the document(s) to the imaging station  210 . If the document(s) is creased or otherwise sticking up from the drop transport  100 , the entry guide  115  deflects the document(s) toward the first pre-feed assembly  124 . The document(s) enter the nip between the drive roller  128  and the driven roller  130 . As the documents enter the nip, the drive roller or upper roller  128  is displaced away from the lower driven roller  130  to provide clearance of the document(s). The thickness detector  138  detects the displacement of the pivot arm  134  as the upper roller moves away when the documents enter the nip of the first pre-feed assembly. Alternatively, rather than thickness detector  138 , a signal from ultrasonic detector  150  indicative of a thick packet of documents may be used. The signal from the thickness detector or ultrasonic detector is communicated with the central controller, and if the thickness detected exceeds a predetermined threshold, then the packet is considered a thick packet, and the drop conveyor  100  is stopped until the thick packet has been fed to the imaging station by the image entry feeder module  110 . Specifically, the system does not advance documents into the first pre-feed assembly  122  until the document(s) being fed from the second pre-feed assembly  124  to the feeder  160  are finished being fed. For instance, if the feeder  160  is feeding a packet of five documents to the imaging station  210 , it is desirable to maintain the grouping of the packet, without mixing the documents in the packet with other documents. Therefore, no further documents are advanced into the second prefeed assembly while that feeder  160  is finishing singulating the documents in the packet. Once the final document in a packet clears the second pre-feed assembly, the system sends a signal to the document transport to advance the next document or packet of documents from the drop feeder to the pre-feed assembly  120 . 
     The image entry feeder  110  module processes single document differently than a packet. Specifically, as the single document passes the ultrasonic thickness detector  150 , the detector determines whether the transaction is a single document or a packet. If the detector  150  determines that the transaction is a single document, the document continues through the second pre-feed roller without stopping. In response to the signal from the ultrasonic detector that the document is a single document, the retard assembly  180  is activated to pivot the singulator away from the feed belts  165 . Specifically, when a single document is detected by the ultrasonic detector, a the controller actuates the cam drive motor  189 , which drives cam drive belt  191 , which in turn rotates the retard pad  182  away form the feed belts  165  to create a gap as shown in  FIG. 6 . The second pre-feeder  124  drives the single document into the nip between the spring mounted idler rollers  170  and the feed belts  165 . In other words, the spring mounted idler rollers provide a nipping surface with the drive belts regardless of whether the retard pad is pivoted upwardly toward the feed belts  165  or down as shown in  FIG. 6 . Since the retard pad is pivoted downwardly, the single document passes through the feeder  160  without engaging the retard, thereby reducing wear on the retard pad. 
     In contrast to the example of a single document, when a packet of documents is fed to the pre-feeders, the ultrasound detector  150  detects a transaction profile that is indicative of a packet rather than an individual document. In response to a signal from the system that the transaction is a packet, the brake  140  is energized. Specifically, once the transaction is determined to be a packet, the brake is energized a predetermined time delay after the time that leading edge of the packet is detected by the pre-feed sensor  152 . However, it may be desirable to energize the brake for each transaction regardless of the whether the transaction is a single document or multiple documents. 
     The timing of braking is independent from the timing of the determination that the transaction is a packet. In other words, the timing of the brake is not measured from the time that the system determines that the transaction is a packet. In fact, in typical operation, the pre-feed sensor  152  will detect the leading edge of a transaction before the system determines whether or not the transaction is a packet in response to the signals from the ultrasound detector  150 . Nonetheless, once the determination is made, the timing of the brake actuation is measured from the time that the leading edge passed the pre-feed sensor. 
     Since the brake is connected to the drive shafts for the lower rollers of pre-feeders  122 ,  124 , actuating the brake  140  impedes the displacement of the lower rollers  130  of the pre-feeders  122 ,  124 . By braking the lower rollers and continuing to drive the upper rollers to drive the packet forward, the top documents in the pack are shifted forwardly relative to the lower documents. In this way, the upper rollers tends to shift the documents in the packet forwardly relative to the bottom documents, causing the packet to shingle so that the leading edge of the top document overhangs the lead edge of the second document in the packet, which overhangs the lead edge of the third document in the packet, and so on, down to the bottom document in the packet. Shifting the top document(s) forwardly facilitates improved singulation of the packet relative to a packet in which the top document in a packet is disposed rearwardly of the documents below in the packet. 
     As described above, once the system determines that a transaction is a packet and the brake  140  is actuated, the pre-feeders start to shingle the documents, which facilitates feeding of the documents to the feeder. Once the system determines that the transaction is a packet, if the retard assembly  180  is in the downward position in which the retard pad  182  is displaced away from the feed rollers, the system actuates the cam drive motor  189 , which rotates the cam  188 , thereby driving the retard pad  182  toward the feeder belts  165  to form a nip between the retard and the feeder belts. 
     As the pre-feed assemblies  122 ,  124  drive the packet forwardly, the first document in the packet enters the nip between the feeder belts  165  and the retard pad  182 , and the nip between the feeder belts  165  and the spring-loaded idler wheels  170 . The feeder belts  165  have a higher coefficient of friction than the retard pad, so that the top document in the packet is engaged and driven through the feeder  160  while the rest of the documents in the packet are held back by the retard. 
     Once the top document in a packet enters the feeder  160 , the feeder belts  165  drive the document through the feeder toward the imaging station  210 . In this way, the feeder separates the lead document from the remaining documents in the packet, thereby singulating the document. As the leading edge of the document leaves the feeder  160 , the feeder exit sensor  215  senses the leading edge of the document. In response, the pre-feed clutch  197  may disengage the driving force transmitted to the upper pre-feed rollers via the pre-feed drive belts  198 ,  199 . Disengaging the pre-feed upper rollers, reduces the tendency of the rollers to buckle the documents, which can occur in response to driving the packet forward toward the feeder while the retard holds the documents back. 
     After the lead document passes the feeder exit sensor  215 , the leading edge of the document enters the nip formed between the crusher rollers  220 . The crusher rollers  220  positively entrain the document and have greater frictional control over the document than the frictional force between the feeder  160  and the document. Therefore, the feeder  160  does not need to drive the document forwardly in order to continue to advance the document. Accordingly, once the leading edge of the document is detected by the sensor downstream from the crusher rollers  220 , such as the thickness detector  227  (or a separate sensor detector similar to the feeder exit sensor  215 ), it is known that the document is entrained by and therefore controlled by the crusher rollers. Therefore, to reduce the likelihood of the feeder  160  feeding the second document in the packet before the first document is completely fed (commonly referred to as a double-feed), the controller may turn off the drive motor  190 , thereby stopping the feeder  160 . Despite the fact that the feeder is stopped, the crusher rollers  210  entrain the document with sufficient frictional force that the crusher rollers drive the document forwardly, pulling it out of the feeder. A one-way overrun clutch allows the belt roller to spin while the feeder motor is stopped while the crusher rollers pull the document out. Once the feeder exit sensor  215  senses the trailing edge of the document, the controller then actuates the drive motor  190  to re-start the feeder to feed the next document in the packet in the same way that the previous document was fed. Additionally, the clutch  197  is actuated to re-connect the pre-feed drive belts  198 ,  199  with the motor  190 , so that the upper rollers of the pre-feed assemblies  122 ,  124  urge the packet toward the feeder  160 . 
     As discussed above, once the system determines that a transaction is a packet, the brake  140  is actuated to brake the lower pulleys of the pre-feeder assemblies  122 ,  124 . However, the motor  190  continues to drive the upper pulleys of the pre-feed assemblies, thereby driving the documents toward the feeder. The rollers of the pre-feed assemblies  122 ,  124  are high friction rollers, so that the lower roller tends to hold back the lower document in a packet. Further, as mentioned above, the lower rollers of the pre-feed assemblies  122 ,  124  are mounted on fixed shafts  131  via torque limiters  132 . The torque limiters are set so that the frictional force between the upper roller and the lower roller is sufficient to overcome the limit on the torque limiter so that when there is no document in the pre-feeder, the frictional force of the driven upper wheel drives the lower wheel forwardly even if the brake is applied. Similarly, the torque limiter is set so that the frictional force between the lower roller  128  in the pre-feeder  122  and a single sheet of paper is sufficient to overcome the limit of the torque limiter so that when there is a single document in the pre-feed assembly, the frictional force of the driven wheel against the single sheet of paper, which in turn engages the lower wheel, drives the lower wheel forwardly even if the brake is applied. Although the limits for the torque limiters  132  are set so that the upper rollers overcome the limits on the torque limiters if there is either no document in the pre-feeders  122 ,  124  or only a single sheet, the limit on the torque limiters is set so that the a paper to paper interface is not sufficient to overcome the torque limiter. In this way, if two or more documents are nipped in the pre-feed assemblies, the frictional force applied to the braked lower rollers by the driven upper rollers through the two documents is insufficient to overcome the limit of the torque limiters, so that the lower rollers remain braked. 
     With the torque limiters  132  set as discussed above, the pre-feed rollers  122 ,  124  control the advance of the documents in a packet, shingling the packet forwardly, while allowing the first and last documents in a packet to be readily fed through the pre-feed assemblies  122 ,  124  even while the brake  140  is applied. 
     Although the foregoing description provides details of a clutching mechanism for selectively controlling the actuation of driving force from the motor  190  to the pre-feed assemblies, in the present instance, the clutch  197  is eliminated so that the top rollers of the pre-feed assemblies continue to drive the documents in the pre-feeder forwardly even when the packet is being held back at the feeder by the retard assembly  180 . 
     Imaging Station 
     From the image entry feeder module  110 , the documents serially enter a nip formed between a pair of crusher rollers  220 . Although the entry feeder holds the documents down, it does not flatten the documents; it generally just holds an edge of the document flat against the base plate of the feeder. In contrast, the crusher attempts to flatten the creased documents. 
     The crusher rollers  220  are elongated cylindrical aluminum rollers  222  having a smooth surface. A plurality of elastomeric gripping rings  224  are formed around the circumference of the roller  222  and spaced apart from one another. Preferably, a first gripping ring is positioned at the end of the roller  224  closest to the entry feeder  110 , and a second gripping ring is positioned on the roller a couple inches away. More specifically, preferably the second gripping ring is spaced inwardly less than the width of the feeder  110 . In addition, preferably a third gripping ring is positioned adjacent the opposite end of the roller. The first and second gripping rings  224  provide nips that drive the paper from the entry feeder to the imager  230 . The third gripping rings are positioned so that they are not in the paper path (i.e. the third gripping rings do not engage the documents. Instead, the third gripping rings provide spacing to maintain the rollers parallel with a constant gap. 
     Preferably, the first two gripping rings  224  on the rollers  222  are positioned so that both rollers engage a single fold for documents that are tri-folded with the fold lines disposed parallel to the paper path. In this way, the gripping rings engage the edge-justified third of the tri-folded document, while the rest of the document can slide across the width of the crusher roller since the remaining width of the crusher roller in the paper path is aluminum. In this way, the crusher roller flattens the documents without buckling the documents. 
     A plurality of feeder exit sensors  215  are disposed in the feeder between the image entry feeder module  110  and the crusher roller  220 . After passing the feeder exit sensors  215  and the crusher roller  220 , the document passes through a thickness detector  227  that measures the document at a plurality of points along the length of the document. In the present instance, the thickness detector  227  is Hall effect-type of sensor, similar to the optional thickness detector  138  described above in connection with the first pre-feed assembly  122 . 
     From the thickness detector  227 , the document enters the imager  230 . Preferably the imager comprises a pair of scanners for scanning both sides of the document. Specifically, preferably the imager  230  includes a lower plate in which the lower scanner  230  is located, and an upper plate in which the upper scanner is located. The lower scanner  230  scans the bottom face of the document, and the upper scanner scans the upper face of the document. As shown in  FIG. 4  preferably the upper plate of the scanner is pivotable upwardly away from the lower plate to allow access into the imaging station  210  in the event of a jam in the imaging station. 
     Although the scanners may be black and white or gray scale, preferably, the scanners  230  are color scanners. More specifically, preferably the scanners  230  are contact image sensor (CIS) modules formed of arrays of photodiodes that operate as scanning elements, and LED light sources. 
     As the document passes between the scanners, the scanners scan the faces of the document to obtain image data representing a color image of the document faces. The image is communicated with the system computer and the image data is stored in a data file associated with the document. 
     From the scanner, the document is conveyed to a MICR detector, which attempts to read any MICR markings on the document. Specifically, MICR markings are printed in magnetizable ink. The MICR detector includes a magnet that exposes the document to a magnetic field. The MICR detector also includes a MICR reader that scans the document for magnetic fluctuations indicative of MICR characters. If the apparatus detects the presence of a MICR line, the MICR detector attempts to read the MICR line. The data representing the MICR information is then communicated with the system computer, which stores the MICR data in a data file associated with the document. 
     Imaging Transport 
     The imaging transport extends between the imaging station  210  and the sorting station  240 . Preferably the imaging transport is formed of two halves, and the upper half is pivotable away from the lower half to provide access to the transport path to remove any paper jam in the transport, or perform service on the interior element, as shown in  FIG. 4 . 
     As shown in  FIG. 1 , the document path between the imaging station  210  and the sorting station  240  is preferably not a straight horizontal path. Instead, preferably, the imaging transport turns upwardly and curves backwardly toward the seating area  15 . Between the imaging station  210  and the sorting station  240 , an optional uncreasing station and a printer may be disposed along the transport path. The uncreasing station is a guide having a sharp edge that the documents pass over as the documents turn along the transport path. If included, the printer is disposed along the transport so that the printer can print markings on the documents as they are conveyed to the sorting station  240 . 
     The printer includes at least one ink jet printer. The printer is disposed behind covers in the imaging transport. More specifically, a first printer is preferably disposed behind a plate in the upper portion and preferably the second printer is disposed behind a plate in the lower portion. In response to signals from the computer, the printer(s) prints audit trail data onto each document. The audit trail information printed on a document includes data particular to the document, such as the document type for each document, the batch number for the document, the document number, the transaction number for the transaction of which the document is a member, and the date on which the document was processed. The audit trail information can be used to subsequently locate a particular document within a stack of documents. 
     Sorting Station 
     The sorting station  240  is disposed at the end of the imaging transport, and the sorting station includes a plurality of gates operable to sort the documents into one of a plurality of bins  245 . The sorting station includes a plurality of gates that are operable to direct the documents to the appropriate bin  245 . The sorting can be based on a number of criteria. For instance, the documents can be sorted according to information determined from the image data. 
     It will be recognized by those skilled in the art that changes or modifications may be made to the above-described embodiments without departing from the broad inventive concepts of the invention. It should therefore be understood that this invention is not limited to the particular embodiments described herein, but is intended to include all changes and modifications that are within the scope and spirit of the invention as set forth in the claims.