Abstract:
A method for scanning documents in a document scanner ( 10 ) includes transporting ( 45 ) documents from an input tray ( 20 ) to an document detection sensor ( 135 A- 135 E); detecting documents with the document detection sensor; capturing image data for a document with an image capture device; determining characteristics of the document based on the image data with an image processor; comparing characteristics of the document to document detection sensor data; and excluding document detection sensor data which conflicts with the image data.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Reference is made to commonly-assigned copending U.S. patent application Ser. No. ______ (Attorney Docket No. K000649US01NAB), filed herewith, entitled DOCUMENT SCANNER, by Link et al.; U.S. patent application Ser. No. 13/272,599, filed Oct. 13, 2011, entitled DETERMINING DOCUMENT CHARACTERISTICS PRIOR TO SCANNING, by Pultorak; and U.S. patent application Ser. No. 13/272,616, filed Oct. 13, 2011, entitled DOCUMENT SCANNER, by Pultorak; the disclosures of which are incorporated herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to extracting properties of documents fed through a document scanner from an input tray by combining imaging data from an image capture device with the machine control document detection sensors to automate the scanner setup, functionality, and behavior. 
       BACKGROUND OF THE INVENTION 
       [0003]    A document scanner moves a document from an input tray, through a transport path and creates an image of the document as it moves past a stationary imaging capture device such as a charge coupled device (CCD) or CIS. Sensors in the transport are used to make sure the document enters the transport correctly. Depending on the type of document or document characteristics, the operator must select functions and features to optimize the scanner to accommodate the specific requirements for a particular document. 
         [0004]    A document scanner includes an input tray for holding documents. A transport system picks the top-most document from the input tray and moves it past one or more document detection sensors as well as an image capture device which acquires an image of the document being scanned on its way to the output tray. The image captured is stored in a buffer memory which is analyzed by an image processor. 
         [0005]    The image processor determines characteristics of documents being scanned, and the documents are processed based on the characteristics. The document characteristic may include the document length, width, position, color, type, or condition of the document. Document detection sensors such as ultrasonic sensors can be used to detect multiple documents fed into the transport at the same time. By combining the ultrasonic data with the characteristics obtained from the document&#39;s image data, an accurate correlation can be made to determine which zone or zones should be used or ignored and which ultrasonic sensor data should be excluded or included during further processing of at least one location within the document based on at least one characteristic. 
         [0006]    In a document scanner, the documents to be scanned may vary by size, weight, color content, physical condition, or other characteristics, which may require different scanner features to be enabled or operator actions to be employed for the most optimal and efficient mode of operation. Since the scanner is not typically programmed with specific requirements on a document-by-document basis, the user may default the scanner to a less efficient set of settings that will process all documents within a batch. Alternately, the operator may manually sort the documents based on common document characteristics. Documents could be sorted based on document characteristics, such as length, width, weight, color, physical condition, or document type. 
         [0007]    Prior art, such as commonly-assigned U.S. patent application Ser. No. 13/272,616, accomplishes this by adding an external image device to the input tray. This method adds additional cost and complexity by adding additional circuitry to support the external camera. In addition since the document is imaged before it enters the transport, any document skew, shifting or slippage due to the feed roller introduces error that is difficult to correct for after the document has move into the transport. Additionally, mischaracterization of the top-most document&#39;s length and size due to the inability to disassociate this document from others in the stack can lead to subsequent document classification scanning errors. 
         [0008]    Knowledge of these many different document characteristics can enable the proper selection of scanner features to improve the efficiency of the scanning process or enable other features which may provide specific applications required by a particular type, style, or size of document. There is a need, therefore, for detection of document characteristics to optimize the operation of the scanner. 
       SUMMARY OF THE INVENTION 
       [0009]    Briefly, according to one aspect of the present invention a method for scanning documents in a document scanner includes transporting documents from an input tray to an document detection sensor; detecting documents with the document detection sensor; capturing image data for a document with an image capture device; determining characteristics of the document based on the image data with an image processor; comparing characteristics of the document to document detection sensor data; and excluding document detection sensor data which conflicts with the image data. 
         [0010]    The present invention eliminates the need for the operator of the scanner to manually enable or disable the one or more document detection sensors based on the input documents and solves the problem of false detection of multi-feeds based on holes in the document or document detection sensors being partially covered by the document. The present invention handles irregular shaped documents where the edge of the document may cross a document detection sensors multiple times. 
         [0011]    The present embodiment uses existing scanner circuitry. Since it uses the actual scanned image data, any document shifting or skew due to the transport feed rollers has already occurred before the document is imaged. Therefore this method accounts for any document shift or skew and can ignore (enable/disable) document detection sensor data within a document to filter out the times when a detection sensor is partially covered either by the end or edge of the document or by a hole in the document thereby maximizing the use of the document detection sensor data over the usable regions of the document. Once the questionable document detection sensor data is ignored, the image processing analysis can correlate document characteristics with the remaining valid data. When a multi-feed is detected, a message is forwarded to cause the desired action; otherwise the document will be processed normally without exception. 
         [0012]    The invention and its objects and advantages will become more apparent in the detailed description of the preferred embodiment presented below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a cross-section view of the side of a document scanner which illustrates the various parts of the scanner related to the present invention. 
           [0014]      FIG. 2  is a perspective view of the scanner transport and illustrates various documents characteristics. 
           [0015]      FIG. 3  is a flow diagram depicting a processing system in accordance with an embodiment of the invention. 
           [0016]      FIG. 4  is a pictorial view of a document with its characteristics and temporal in a transport relative to document detection samples as the document travels through the transport before processing. 
           [0017]      FIG. 5  is a pictorial view of a document with its characteristics and temporal in a transport relative to document detection samples as the document travels through the transport after processing. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    The present invention will be directed in particular to elements forming part of, or in cooperation more directly with the apparatus in accordance with the present invention. It is to be understood that elements not specifically shown or described may take various forms well known to those skilled in the art. 
         [0019]      FIG. 1  is a side cross-sectional view of a document scanner  10 . The illustration shows the input tray  20  with document  11  waiting to be scanned by the scanner. A typical scanner also has a transport  45  for moving documents through the scanner and an output tray  18  for collecting documents as well as other components that makeup a document scanner. 
         [0020]    As shown in  FIG. 1 , documents are first placed in the input tray  20  of the scanner. The feed roller  40  within the feed module  42  selects and pulls top document  11  from the input tray  20  into the transport  45 . At the same time top document  11  moves into the transport  45 , the document in contact below top document  11  may also move forward but is prevented from entering the transport by the separator roller  41 . However, sometimes the document directly below top document  11  is pulled into the transport due, for example, to static. 
         [0021]    As top document  11  travels through the transport  45 , it passes document detection sensors  135 A- 135 E, top imaging aperture  32  and the bottom imaging aperture  36 . The top imaging device  30  images the document as it passes the top imaging aperture  32  while bottom imaging device  35  images the document as it passes the bottom imaging aperture  36 . As sensor data from the document detection sensors  135 A- 135 E and the image data from the top imaging device  30  and bottom imaging device  35  are captured, they are transmitted to be processed by a processor shown schematically as processing block  120 . 
         [0022]    The processing block  120  processes the image data, to determine document characteristics. These characteristics will be temporally combined with the document detection sensors  135 A- 135 E data to enable or disable a particular feature or operation of the scanner based on the document characteristics. 
         [0023]    Within  FIG. 2  is a perspective view of the scanner transport which illustrates various documents characteristics. Some document characteristics that are important in processing the document in regards to corresponding the document detection sensing data are the document length  70 , width  80 , holes  82  in the document or adhesive label  84  or stick on note  86  on the document. With regards to the transport, the physical document detection sensor to top aperture distance  200  and the document detection sensor to bottom aperture distance  210  are required for properly temporal synchronization of the digital image data  310  (in  FIG. 3 ) and digital sensor data  375  ( FIG. 3 ). 
         [0024]    In considering the flow diagram within  FIG. 3 , the image data and document detection sensor data captured is sent to the processing block  120  to be processed. The scanner process consists of a document to capture 300 (top document  11  in  FIG. 1  and  FIG. 2 ), which can be a text document, photograph, or some combination thereof; a capture image  305  step which consists of an imaging device which focuses light from the document to capture 300 onto an imaging sensor (not shown), for example, a single-chip color CCD or CMOS image sensor, and a Analog-to-Digital (A/D) converter, to produce digital image data  310 . The digital image data  310  is processed by the identify document characteristics  315  step which will determine the length  70  and width  80  of the document, along with the location of the top document  11  boundaries. In addition the identify document characteristics  315  step will look within the document boundaries for additional characteristics such as holes  82 , adhesive label  84  or stick on note  86 . These document characteristics including their locations will be saved to buffer memory during the store document image characteristics  325  step. At the same time, the document detection sensor to sample  350  is being sampled by the analog-to-digital conversion  360  step to produce digital sensor data  375 , which is saved during the store digital sensor data  380  step. 
         [0025]    The scanner transport profile  390  consists of scanner transport parameters such as document detection sensor to top aperture distance  200  ( FIG. 2 ) and document detection sensor to bottom aperture distance  210 . The controller  395  will determine when the feed roller  40  ( FIG. 1 ) is enabled to start to bring the top document  11  into the transport  45 . 
         [0026]    It will be understood that the functions of the controller  395  can be provided using a single programmable processor or by using multiple programmable processors, including one or more digital signal processor (DSP) devices. Alternatively, the controller  395  can be provided by custom circuitry (e.g., by one or more custom integrated circuits (ICs) designed specifically for use in digital scanners), or by a combination of programmable processor(s) and custom circuits. 
         [0027]    The controller  395  will use the document detection sensor to top aperture distance  200  and document detection sensor to bottom aperture distance  210  along with the speed of the transport motors to determine when the lead-edge of the document reaches the document detection sensors  135 A- 135 E, the top imaging aperture  32 , and the top imaging aperture  36 . Knowing this timing, the location of the stored sample data of top document  11  within the buffer memory used by the store document image characteristic  325  step and digital sensor data  375  within the buffer memory of the store digital sensor data  380  step can be identified. Knowing these temporal locations and the sampling rate of the analog-to-digital conversion  360  step and the sampling rate of the capture image  305  step, the offset in memory can be calculated to merge the digital sensor data  375  and the document image characteristics  320  during the merge image and sensor data  330  step. 
         [0028]      FIG. 4  shows a pictorial view of merged and temporally aligned digital image data  310  and digital sensor data  375  that result from the merge image and sensor data  330  step. The document characteristics and position in a transport relative to document detection samples  410 A,  410 B,  410 C,  410 D and  410 E are shown. In this embodiment, the document characteristics are, but not limited to the width  80 , length  70 , holes  82 , adhesive label  84  and stick on note  86 . 
         [0029]    A set of usable data rules  338  ( FIG. 3 ) are applied during the extract usable sensor data  335  step and determine what sensor data shall be used and what sensor data shall be excluded. For example, to determine if the feed roller  40  pulled in multiple documents into the transport  45 , only sensor data that falls inside of the document&#39;s boundaries is included. Since the sensor data from the document detection sensors  135 A- 135 E can produce false readings when the sensor partially falls on a document, this data can also be excluded during the extract usable sensor data  335  step ( FIG. 3 ) to reduce the likelihood of a false detection. In the  FIG. 4 , this would include the document detection sensor sample  410 E that is taken along the boundary of top document  11 . In addition, the document detection sensor samples  410 A are sometimes temporally taken over holes  82 . The sensor sample at these locations can also be likewise excluded. 
         [0030]    In some circumstances, the operator may want to consider top document  11  with a stick on label  86  on it as a multi-feed error while considering adhesive label  84  on top document  11  as not being a multi-feed error. In this situation the document detection sensor sample  410 D that are temporally located over the adhesive label  84  are excluded while keeping the document detection sensor sample  410 C that are temporally located over the stick on label  86  are not excluded. 
         [0031]    In other embodiments, additional information from the top imaging device  30  and bottom imaging device  35  could be different. For example, the front could be configured to exclude document detection sensor samples over adhesive label  84  while including those corresponding samples located at the adhesive label  84  on the rear side of the document. 
         [0032]    The color content from the top document  11  can also be used to define how the samples from the document detection sensors  135 A- 135 E are used. For example, the color of a document characteristic can be used to exclude or include document detection sensing in the area of a specific the document characteristic. In this example the document detection sensor sample  410 A- 410 E over a red stick on note  86  could be excluded while allowing document detection sensor sample  410 A- 410 E over a yellow stick on note  86 . 
         [0033]    Once the extract usable sensor data  335  step ( FIG. 3 ) has been completed, only usable document detection sensor data within the document  340  remains which is then used in the process sensor data  345  step.  FIG. 5  shows the digital sensor data  375  that is actually used by the process sensor data step  345 . 
         [0034]    In other embodiments, the document characteristics could be used to control the output rollers  100  for controlled stacking or sorting. For example, document of certain size or type such as checks, could be routed or sorted into a different output tray  18  by changing the path top document  11  takes with the transport  45  or by changing the speed of the output rollers  100 . Still in other embodiments, documents that fall outside of an operator&#39;s defined set of parameters or exceptions during the process sensor data  345  step could be held at the output rollers  100  for easy access by the operator. 
         [0035]    The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention. 
       PARTS LIST 
       [0000]    
       
           10  scanner 
           11  top document 
           18  output tray 
           20  input tray 
           30  top imaging device 
           32  top imaging aperture 
           35  bottom imaging device 
           36  bottom imaging aperture 
           40  feed roller 
           41  separation roller 
           42  feed module 
           45  transport 
           70  document length 
           80  document width 
           82  holes 
           84  adhesive label 
           86  stick on note 
           100  output rollers 
           120  processing block 
           135 A- 135 E document detection sensor 
           200  document detection sensor to top aperture distance 
           210  document detection sensor to bottom aperture distance 
           300  document to capture 
           305  capture image step 
           310  digital image data 
           315  identify document characteristics step 
           320  document image characteristics 
           325  store document image characteristics step 
           330  merge image and sensor data step 
           335  extract usable sensor data step 
           338  usable data rules 
           340  usable sensor data within document 
           345  process sensor data step 
           350  document detection sensor to sample 
           360  analog-to-digital conversion step 
           375  digital sensor data 
           380  store digital sensor data step 
           390  scanner transport profile step 
           395  controller step 
           410 A- 410 E document detection sensor sample