Abstract:
The invention provides an improved method and system for processing mail items on bar code sorting machines. Such a method includes the steps of scanning a surface of each mail piece with at least one imaging camera to obtain at least one image of the surface represented by image data, analyzing the image data to locate a bar code in the image, and analyzing the bar code to recognize a first destination code. If the first destination code meets predetermined criteria, then the mail piece is processed further in a manner dependent on the first destination code. If the first destination code cannot be recognized or fails to meet the predetermined criteria, the image data is analyzed to locate destination address lines in the image, and the address lines are analyzed to determine a second destination code. The mail piece is sorted according to the second destination code, or a result determined by arbitrating the first and second destination codes.

Description:
[0001]    This application claims priority of U.S. Provisional Patent Application Ser. No. 60/436,339, filed Dec. 24, 2002. 
     
    
     
       TECHNICAL FIELD  
         [0002]    The present invention relates to the automated processing of images, in particular to the scanning and processing of images of mail pieces to decode address and other information.  
         BACKGROUND OF THE INVENTION  
         [0003]    Current state-of-the art postal letter mail equipment is divided into two types, those that primarily process addresses, and those that process mail that has been bar coded. Bar code processing equipment is simpler in design and does not require as long a transport belt path because the time to process a mail piece image is less for one containing a bar code than one containing only address information. Bar codes typically included on mail items are traditional linear bar code types as well as two dimensional code patterns that contain alphanumeric and ZIP code data.  
           [0004]    Many efforts to improve bar code recognition have been employed to increase the effective yield of the machines to as high as 90%, but ultimately severely degraded images, or those wherein the bar code is obscured by an envelope&#39;s window edge, cause a certain percentage of mail items to be rejected. Mail items with bar codes that cannot be read are rejected and either processed manually or reprocessed on other equipment capable of reading the full address. These later steps result in additional costs and delay in processing the mail items, and depending upon the specific step of the production process, this can sometimes result in an extra day to deliver the item.  
           [0005]    Some bar-coded mail items have an additional identification code used to associate an image with the mail item. These pieces had been previously processed and a sorting bar code applied by an OCR sorting system as deployed by the USPS, or by a mail processing companies that have equipment similar to the USPS and who are operating under license to the USPS. The ID code is read by a separate bar code reader and is used by the bar code sorters to enable each to query a central server for bar code equivalent data when sorting bar codes cannot be read. The server receives the bar code equivalent data, i.e., data from which a correct destination bar code for that mail piece can be determined, from a process such as video coding. A need persists for a system able to provide a higher read success rate for bar code sorters.  
         SUMMARY OF THE INVENTION  
         [0006]    The invention provides an improved method and system for processing mail items on bar code sorting machines. Such a method includes the steps of:  
           [0007]    (a) scanning a surface of each mail piece with at least one imaging camera to obtain at least one image of the surface represented by image data;  
           [0008]    (b) analyzing the image data to locate a bar code in the image;  
           [0009]    (c) analyzing the bar code to recognize a first destination code;  
           [0010]    (d) if the first destination code meets predetermined criteria, then processing the mail piece further in a manner dependent on the first destination code; and  
           [0011]    (e) if the first destination code cannot be recognized or fails to meet the predetermined criteria, then analyzing the image data to locate destination address lines in the image, analyzing the address lines to determine a second destination code, and processing the mail piece further in a manner dependent on one of the second destination code, or a result determined by arbitrating the first and second destination codes.  
           [0012]    These steps are generally executed on a mail sorting machine which may be equipped with one or two imaging cameras or scanners. If two cameras are present, then step (a) contemplates that one image can be made to locate the bar code and another to locate destination address lines. In the alternative, a single image can be analyzed using known region of interest strategies to obtain both the destination address lines image data and the bar code image data. The process of arbitration, described further below, is optional. In the simplest embodiment of the invention, if the bar code does not adequately give the destination code (unreadable, outdated, or only gives part of the code), then the second destination code is used to determine how the item is sorted or otherwise processed. If both the bar code and address lines prove unreadable, the mail item is a reject.  
           [0013]    The invention further provides an apparatus for sorting a series of mail pieces according to the method set forth above. Such an apparatus includes a conveyor which transports a series of mail pieces, generally a pair of upright belts holding each mail piece from either side for transport on edge. The conveyor ultimately conveys each mail piece to a series of diverters which are each operable to divert mail pieces from the conveyor to one of a series of sorting destinations, e.g., bins or slots. An imaging camera is positioned proximate the conveyor for scanning a surface of each mail piece to obtain an image of the surface represented by image data. A computerized control system analyzes the image data to locate a bar code in the image and analyzes the bar code to recognize a first destination code. If the first destination code meets predetermined criteria, the control system sorts the mail piece by actuating one of the diverters in a manner dependent on the first destination code. If the first destination code cannot be recognized or fails to meet the predetermined criteria, the system then analyzes the image data to locate destination address lines in the image, analyzes the address lines to determine a second destination code, and sorts the mail piece by actuating one of the diverters in a manner dependent on one of the second destination code, or a result determined by arbitrating the first and second destination codes. These steps can be carried out by any appropriate combination of hardware and software.  
           [0014]    These and other aspects of the invention are further described and discussed in the detailed description which follows. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0015]    In the accompanying drawing, wherein like numerals represent the same or similar elements throughout:  
         [0016]    [0016]FIG. 1 is a typical sorting machine elevator section which can be used in the invention;  
         [0017]    [0017]FIG. 2 is a schematic diagram of a system for scanning mail pieces according to the invention; and  
         [0018]    [0018]FIG. 3 is a schematic diagram of an alternative apparatus according to the invention.  
     
    
     DETAILED DESCRIPTION  
       [0019]    Optical character reader (OCR)-assisted bar code reading (BCR) according to the invention can provide recognition of the address and other text and pattern information on the mail piece for subsequent sortation to the correct machine pocket. Significant performance improvements on the remaining bar code rejects can be gained utilizing this method. A computer processor is used to implement the OCR and pattern recognition on the traditional bar code sorting machines (a total of over 8,000 USPS bar code sorters, including Delivery Point Bar Code Sorters-DBCS, Carrier Sequencing Bar Code Sorters-CSBCS and Delivery Input Output Sub Systems-DIOSS). The existing sorter system computer is augmented with an OCR/pattern recognition computer. This computer performs the traditional bar code reading function. OCR and text pattern recognition software processes are initiated for those mail pieces that have no bar code (i.e. bar code slipped behind the window) or have an unreadable bar code, thereby providing additional read performance for mail items that do not contain a bar code or contain unreadable or damaged bar codes.  
         [0020]    Referring to FIGS. 1 and 2, a system  10  according to the invention includes a paired belt conveyor  11  which is part of a postal sorting machine. At the sorting machine elevator section shown in FIG. 1, mail carried by conveyor  11  passes by a wide field of view digital camera  13 . Camera  13  captures an image of the mail piece surface that will be analyzed for address information in accordance with the invention. Immediately after scanning, each mail piece passes by a first photo cell or light barrier  14  and enters an idler section  16  of the conveyor that leads to the diverter gates  17 . In typical bar code sorting machines used in the U.S. postal system, first photo cell  14  is located some distance from the first mail path diverter gate  17  that separates mail streams into different levels. In this implementation, the time from photo cell  14  to a second diverter gate photo cell  18  can be utilized for arbitration of differing results and returning the best ZIP code and sort decision result. In this implementation, in other words, the additional latency time is utilized for processing. This would not be possible with a standard configuration that requires the bar code reader output results at a fixed time interval.  
         [0021]    The output of the image lift camera  13  is passed to both bar code recognition  21  and OCR recognition  22  process modules which form part of the control system  20 . Output from photocell  14  is provided to image lift camera  13  for transfer to the bar code recognition module  21  for synchronization with the bar code recognition process and also to the OCR recognition module  22  to assure that the OCR process is synchronized with results that are determined by the bar code recognition process. Numerous methods of can be employed for synchronizing these data such as time stamping the output, optical encoder counts, or other methods that are well known in the art. Both bar code and OCR processes  21 ,  22  can be initiated in parallel with the acquisition of the image data. Alternatively, either process can await suitable portions of the image information to be delivered prior to beginning process execution. Processes  21 ,  22  are embodied in program logic that can be run as multiple tasks on a single computer, or multiple computers or processors may be provided.  
         [0022]    Bar code recognition normally completes execution sooner than OCR recognition. The results of this process are provided to the machine control module  24 , operable from a user terminal  23 , which determines the destination sort location for the item represented by the image. This result is buffered to await the OCR process resolution, or an interrupt from the sort decision second photocell  18  that informs machine control  24  that a decision must be provided. Occasionally, the result from the bar code decision process  21  is that there is no valid result and subsequent sort decision.  
         [0023]    “Buffering” as used in the present invention refers to the process of maintaining in computer memory or storing to a computer storage medium data a series of data elements, such as images captured from a device such as a camera or scanner. Generally the buffer will contain such data long enough for an intended purpose, such as decoding, to be completed. At typical sorting speeds, 10 or so mail pieces may be in the process of being transported between photocells  14  and  18 . The computer memory buffer maintains image data for these mail pieces in order of arrival, and the processes described are carried on simultaneously for each of the mail pieces then in transit. Data is dropped from the buffer, if not saved for later reference, once the associated mail piece passes by the second photocell  18 .  
         [0024]    When the OCR decision data are received from the OCR process, the data are compared with the bar code decision data for the same mail piece. An arbitration process  25  determines which result to use and provides that output to machine control. Machine control  24  can also provide a result to OCR process  22  to inform it that a successful bar code result has been received. Depending upon the system resources then available, the OCR module  22  can terminate processing on the appropriate image, or continue to completion. If resources for processing a subsequent image are marginal or low, this feature enables stopping processing on one image to reallocate resources (memory or machine cycles) to work on a subsequent one.  
         [0025]    In some systems, such as DIOSS machines, the machine is also provided with an bar code ID tag or RFID tag reader  26 . These devices permit the machine to read ID codes off of a mail piece previously determined to be unreadable in a postal sorting process. The mail piece was ID tagged and diverted for human review (video coding) so that a valid address and destination code could be determined. When such a tag is detected, control module  24  consults an external database wherein the results of video coding are correlated with ID codes. The destination ZIP code to be used for sorting or other processing is then the one matching the ID tag, which would override any result determined by OCR or bar code processes  21 ,  22 .  
         [0026]    If idler section  16  is sufficiently long and sufficient computing resources are available, it is preferred according to the invention for the results from processes  21 ,  22  to be processed by arbitrator module  25 . “Arbitration” in postal processing refers generally to software (program logic) that compares results from two different, usually parallel processes and decides which to use based on predetermined criteria or selection rules. Arbitration can also involve combining information from two or more upstream processes to reach a result most likely to be accurate. In the process of the present invention, arbitration is not normally needed if, as in a majority of cases, the destination bar code is fully readable (to eleven digits in the case of a ZIP code.) Arbitration may be needed where the results from processes  21 ,  22  return a different number of digits, for example, the bar code is readable to 5 or 7 digits but the OCR process results in 11 digits. If the first 5 or 7 digits of the OCR process match the bar code result, the arbitration rules might then dictate that the 11 digit result be used. Arbitration can also be used in the event that the bar code is readable but proves to be invalid, outdated or incorrect to minimize sorting on such bar codes. The result of arbitration is sent to control module  24  and is used as the basis for further processing. The rules for arbitration are determined in advance according to user preference.  
         [0027]    As noted above, the bar code recognition process  21  and OCR process  22  may run in parallel. For example, OCR process  22  works on locating the address coordinates and location of the address lines while bar code process  21  decodes the bar code. If bar code recognition is not successful, or if the bar code does not meet predetermined criteria, then process  22  continues to determine the destination ZIP Code and other address data. In the alternative, time permitting, the start of process  22  is delayed until process  21  is completed and a bar code that does not meet the conditions for validity (e.g., unreadable, not enough digits, obsolete or invalid) has been detected. Upon completion of process  22 , the destination address is converted into bar code equivalent data, that is, a delivery code such as a ZIP code. This may require reference to a master database of addresses and associated delivery codes, as in a case where the address can be read but no zip code is provided or only a 5-digit zip code is provided.  
         [0028]    According to another aspect of the invention, an ID tag may be applied to mail pieces for which processes  21  and  22  fail to result in a destination code enabling a sorting decision. This is the starting end of the process discussed above wherein previously applied ID or radiofrequency ID tags are read. As shown in FIG. 3, in an alternative embodiment of the invention, a DIOSS machine  30  includes an ID tagger  31  downstream from camera  13 , preferably a sufficient distance so that a decision can be made concerning each mail piece before it passes tagger  31 . An ink jet printer  32  then prints the scannable ID code on to the mail piece, and the mail piece enters a drying loop  33  before it reaches the first diverter gate  17 . The control computer stores the image data indexed to the I) number in a storage medium (e.g., hard drive) for later retrieval. The OCR results, such as a partial address, may also be stored for later review, indexed to the same ID number. The mail piece is then sorted to a reject bin for subsequent processing, such as video coding. Once video coded, the mail piece can then be reintroduced to a sorter equipped with an ID tag reader as described above.  
         [0029]    Use of the systems and processes of the invention can improve read rates on currently deployed bar code sorters by from 1 to 3 percent, resulting in large cost savings without any significant changes to the postal processing equipment. Although various embodiments of the invention have been illustrated in the accompanying drawings and described in the foregoing detailed description, it will be understood that the invention is not limited to the embodiments disclosed but, as will be appreciated by those skilled in the art, is susceptible to numerous modifications and variations without departing from the spirit and scope of the invention as hereinafter claimed.