Patent Publication Number: US-2003231358-A1

Title: System and method for automatically feeding documents to a scanning device

Description:
TECHNICAL FIELD OF THE INVENTION  
       [0001] This invention relates to imaging systems and, more particularly, to a system and method for feeding documents to a scanning device.  
       BACKGROUND OF THE INVENTION  
       [0002] Document scanners convert a visible image on a document, photograph, a transparent media and the like into an electronic form suitable for copying, storing and processing by a computer. A document scanner may be a stand-alone device or integrated with a copier, a facsimile machine, a multipurpose device, etc.  
       [0003] Flat bed scanners are stationary devices which have a transparent plate or platen upon which an object to be scanned, such as a paper document, is placed. The document is scanned by sequentially imaging narrow strips, or scan line portions, of the document on a linear optical sensor array such as a charge coupled device (CCD). The optical sensor array produces electronic data which is representative of each scan line portion of the document which is imaged thereon.  
       [0004] In one type of flat bed scanner, the current scan line portion of the document which is imaged on the sensor array is changed, or “swept”, by moving the platen supporting the document relative to the scanner imaging assembly. In another type of flat bed scanner, the platen and document remains stationary and at least a portion of a imaging assembly is moved to change the scan line portion which is currently imaged. Flat bed scanners of the second type are sometimes provided with automatic document feeders (ADFs) integrated within a scanner cover which sequentially move sheet documents across a portion of the scanner platen. When an ADF is used, the portion of the imaging assembly which ordinarily moves during scanning remains stationary and relative movement between the document and imaging assembly is provided by the ADF. However, conventional ADFs utilize a window, or other transparent panel, for providing a scan region through which scan lines of an image are made. The window of an ADF has a propensity to become deteriorated, soiled, scratched, or otherwise damaged such that the translucence thereof is decreased. The scanned image quality of documents imaged during passage of an ADF window deteriorates in relation to the loss of translucence of the window.  
       SUMMARY OF THE INVENTION  
       [0005] In accordance with an embodiment of the present invention, a device for feeding documents to be scanned to a scanning device comprising a device chassis having an elongate opening aligned along a transverse axis of the device, the elongate opening disposed on a bottom surface of the device chassis and adjacent a platen surface when the device is positioned for performing a scan operation, a first guide that provides at least a portion of a document feed path, the first guide comprising a first surface defining a first vertex, a second guide that provides at least a portion of the document feed path, the second guide comprising a second surface defining a second vertex, the first vertex disposed at a greater distance than the second vertex relative to the platen surface, and an imaging roller rotationally operable to engage a document and drive the document past the elongate opening into impingement with the second guide, the document having an anterior edge that is driven past the first vertex prior to traversing the second vertex and impinging with the second guide, the imaging roller imparting the document with a sufficient trajectory such that the anterior edge does not impinge the platen surface is provided.  
       [0006] In accordance with another embodiment of the present invention, a method of feeding a document to be scanned to a scanning device from a document feed device comprising picking a document from an input support, driving the document through traversal of a first portion of a feed path defined by a first guide, the document comprising an anterior edge, a posterior edge, and an intermediate portion therebetween, traversing, by the anterior edge, a scan region defined by an opening in the feed device optically coupled with the scanning device, the document traversing the scan region without impinging a plane of the opening, impinging the anterior edge with a second guide, and driving the document through traversal of a second portion of the feed path defined by the second guide is provided. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0007] For a more complete understanding of the present invention, the objects and advantages thereof, reference is now made to the following descriptions taken in connection with the accompanying drawings in which:  
     [0008]FIG. 1 is a perspective view of a document scanner system connected to a computer in which an embodiment of the present invention could be employed to advantage;  
     [0009]FIG. 2 is a cross-sectional side view of reflective scanner in a configuration for scanning an image on an opaque media in which an embodiment of the present invention could be employed to advantage;  
     [0010]FIG. 3 is a simplified perspective diagram of an automatic document feeder that may be used for scanning one or more documents on a scanner device in which an embodiment of the present invention could be employed to advantage;  
     [0011]FIG. 4 is a schematic side cross-sectional view of the automatic document feeder according to the prior art;  
     [0012]FIG. 5 is a schematic of a drive mechanism that employs a direct current motor and a transmission to drive a shaft on which a top feed roller is mounted via a gear according to the prior art;  
     [0013]FIG. 6 is a schematic side cross-sectional view of an automatic document feeder and a reflective scanner in a configuration for sequentially scanning a plurality of documents according to the prior art;  
     [0014]FIGS. 7A and 7B are, respectively, a simplified cross-sectional schematic of a document scanner and an automatic document feeder integrated within a scanner cover in which an embodiment of the present invention may be employed to advantage;  
     [0015]FIG. 8A is a schematic side-view of a feed roller and an imaging roller in a configuration according to an embodiment of the present invention;  
     [0016]FIG. 8B is a schematic side-view of the feed roller and imaging roller of FIG. 8A after passage of an anterior edge of a document through a scan region according to an embodiment of the present invention;  
     [0017]FIG. 8C is a schematic side-view of the feed roller and imaging roller of FIGS. 8A and 8B with the imaging roller repositioned to facilitate scanning of a document according to an embodiment of the present invention;  
     [0018]FIG. 8D is a schematic top-view of the feed roller and imaging roller of FIGS.  8 A- 8 C in a configuration of the present invention;  
     [0019]FIG. 9 is a side sectional schematic and of an automatic document feeder having an elongate opening in a bottom surface of a chassis thereof that defines a scan region in which one or more documents may be scanned during traversal according to an embodiment of the present invention; and  
     [0020]FIG. 10 is a top sectional schematic of the automatic document feeder described with reference to FIG. 9 according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
     [0021] The preferred embodiment of the present invention and its advantages are best understood by referring to FIGS. 1 through 10 of the drawings, like numerals being used for like and corresponding parts of the various drawings.  
     [0022] In FIG. 1, there is a perspective view of a document scanner system  50  connected to a computer  10 . Document scanner system  50  includes reflective scanner  100  which includes a transparent platen  110  against which the document to be scanned is placed. Computer  10  may be coupled to, and facilitate control of, document scanner system  50  via an external peripheral interface  15  such as a parallel interface, a universal serial bus interface or other communications medium. Computer  10  may include one or more input devices, such as a keyboard  30  and a mouse  40 , that allow user interaction therewith and facilitate user control of scanner system  50 . One or more output devices, such as a monitor  20 , a printer (not shown), memory, data storage devices or another device, may allow transfer of data from the computer  10  to an external system.  
     [0023]FIG. 2 is a cross-sectional side view of reflective scanner  100  shown in a configuration for scanning an image on an opaque media  125 . Scanner  100  includes an internal lamp  215 . Lamp  215  may be attached to a carriage  219  operable to impart a linear motion of the lamp along a rail  217  or another structure. An optic system (not shown) may also be included on carriage  219  as well as a photosensitive device  221  such as an array of CCDs. Opaque media  125  is placed on platen  110  of scanner  100 . As carriage  219  moves lamp  215  along the length, or a portion thereof, of rail  217 , light from lamp  215  is directed onto the image on opaque media  125  through platen  110  and reflected. The reflected light is collected by an internal optic system (not shown) and directed onto photosensitive device  221  where the light is converted into one or more electric signals. Generally, carriage  219  has a home position (X=0) from which scan operations are initiated. As light is radiated from lamp  215 , carriage  219  moves through a translation distance (X) along rail  217 . Photosensitive device  221  converts light radiated from lamp  215  as carriage  219  moves through the distance X.  
     [0024]FIG. 3 is a simplified perspective diagram of an automatic document feeder (ADF)  300  that may be used for scanning one or more documents on a scanner device, such as reflective scanner  100 . ADF  300 , in general, comprises a chassis  310  that houses one or more feeder components and associated circuitries. Chassis  310  may comprise an input tray  320  that supports one or more document originals to be scanned by scanner  100 . Input tray  320  may have an input extension  330  that supports large documents, such as 11×17 inch documents, A4 sized documents, or other large documents that may extend beyond the structure of input tray  320 . Input tray  320  may have one or more document guides  350  that facilitate feeding of various width documents by ADF  300 . ADF  300  may have an output tray  340  for receiving documents as they are ejected from ADF  300  upon completion of a scan.  
     [0025]FIG. 4 is a schematic side cross-sectional view of ADF  300  with a generally flat horizontally extending table or platen surface  335  having a ADF window  390  at one end thereof through which a document to be scanned can be viewed by the scanning components of a scanning device, such as reflective scanner  100 . Input tray  320  may have an inclined frame that facilitates feeding of one or more documents  315  to ADF  300 . ADF  300  may have one or more paper guides  380 - 382  disposed in chassis  310  that define a paper path extending from input tray  320  to ADF window  390  and past a document imaging roller  370  and a document output roller  395  to a scanned document output location at which output tray  340  is preferably provided for receiving a stack of scanned documents. The apparatus for feeding individual sheets of documents  315  to a scan region provided by ADF window  390  includes input tray  320  and may include one or more upper and lower media feed rollers  360  and  361  and a suitable drive mechanism for rotating rollers  360  and  361 . An output roller  395  may be disposed within chassis  310  that facilitates ejection of a scanned document into output tray  340 .  
     [0026] A drive mechanism for rotating rollers  360  and  361  can take any one of various forms. One form of drive mechanism  500  is schematically shown in FIG. 5 and employs a small DC motor  510  and transmission  520  to drive shaft  530  on which the top feed roller  360  is mounted via gear  540 . Similarly, a second small DC motor  511  is used to drive bottom feed roller  361  which is mounted on shaft  531  through a transmission  521 . Drive mechanism  500  is exemplary only and various configurations are possible. For example, a single DC motor may be employed by drive mechanism  500  for driving rollers  360  and  361 . The configuration of imaging rollers  360  and  361  may be substituted with various other roller configurations as well and may employ a single driver roller or more than two imaging rollers. A similar or common drive mechanism may be employed to drive imaging roller  370  and/or output roller  395 .  
     [0027] Modern scanning systems allow various controls and system parameters to be controlled or manipulated by a user through user interactions with software modules executed on computer  10 . For example, a user interacting with computer  10  may vary exposure rates performed by reflective scanner  100  when performing a particular type of scan. Invocation of various scan controls and image processing directives are possible through computer control of scanner system  50 .  
     [0028] To facilitate performing multiple sequential scans of a plurality of documents with reflective scanner  100 , the user may provide directives that instruct reflective scanner  100  to operate in coordination with ADF  300 . As mentioned hereinabove, when an ADF is used, the portion of the imaging assembly which ordinarily moves during scanning remains stationary and relative movement between the document and the imaging assembly is provided by the ADF. Accordingly, the user may provide input into a computer coupled to a reflective scanner that results in the computer directing the reflective scanner to perform a scan operation with the carriage assembly in a stationary position. Alternatively, a command to direct the scanner to perform a stationary carriage scan may be provided by ADF  300  or may be provided by an input made directly to scanner  100  itself.  
     [0029]FIG. 6 is a schematic side cross-sectional view of ADF  300  and reflective scanner  100  in a configuration for sequentially scanning a plurality of documents  315 . Documents  315  are supported by input tray  350  such that in a normal operating position, a document  315 A may be picked from documents  315  upon engagement therewith by feed rollers  360  and  361 . As document  315 A is picked by rollers  360  and  361 , a motion is imparted thereto and the translation of document  315 A is defined by one or more of guides  380  and  382  until document  315 A is engaged with imaging roller  370 . Document  315 A is driven across ADF window  390  upon engagement with imaging roller  370 . In a configuration for scanning documents automatically fed by ADF  300 , carriage  219  is positioned below ADF window  390  such that light radiated from lamp  215  will pass through platen  110  and ADF window  390  and reflect from a portion of document  315 A adjacent ADF window  390 . The light reflected from the portion of document  315 A then passes through ADF window  390  and platen  110  and thereafter may be collected by the optic system and photosensitive device  221 . Thus, ADF window  390  defines a scan region through which scan lines may be sequentially imaged as document  315 A is driven past ADF window  390 . As document  315 A is driven past ADF window  390 , one or more guides  381  and  382  may direct document  315 A along a path toward output tray  340 . Output roller  395  may be disposed within chassis  310  and may engage document  315 A such that ejection of document  315 A into output tray  310  is facilitated.  
     [0030] As mentioned hereinabove, ADF window  390  has a propensity to become soiled, scratched, or otherwise impure such that the translucence thereof is decreased. Scanned image quality of documents  315  made by passing documents by ADF window  390  deteriorate in relation to the loss of translucence of ADF window  390 .  
     [0031] With reference now to FIGS. 7A and 7B, there is a simplified cross-sectional schematic of a conventional scanner  550  that may have an ADF integrated within a cover assembly  560  coupled therewith. A conventional ADF integrated within cover assembly may comprise one or more feed rollers and imaging rollers and one or more drive assemblies in a configuration similar to that described hereinabove with reference to FIG. 5 or in another of various configurations. Cover assembly  560  may be rotateably attachable to scanner  550  and may, accordingly, have one or more hinges  575  for removeably coupling assembly  560  with scanner  550 . Scanner  550  includes internal lamp  215  attached to carriage  219  operable to impart a linear motion of the lamp along rail  217  or another structure. An optic system (not shown) may also be included on carriage  219  as well as a photosensitive device  221  such as an array of CCDs. Scanner  550  may operate in one of two general modes: scanning of a single document or scanning of multiple documents facilitated by the ADF assembly integrated within cover assembly  560 . In a first operational mode, a document to be scanned is placed on platen  110  and a scan operation is thereafter initiated. In such a mode of operation, the imaging assembly, that is carriage  219  and imaging components disposed thereon, or otherwise coupled thereto, moves lamp  215  through a translation distance (X) along a length of rail  217  and light from lamp  215  is directed onto the image on the document through platen  110  and reflected. The reflected light is collected by an internal optic system and directed onto photosensitive device  221  where the light is converted into one or more electric signals. In a second operational mode, a plurality of documents, or other media to be scanned, are sequentially fed by an ADF apparatus integrated within scanner cover assembly  560 . In the second operational mode, cover assembly  560  is placed in a “closed” position such that a bottom surface  580  is adjacent a top surface  115  of scanner  550 . Cover assembly  560  may have a document input tray  565  for supporting a plurality of documents to be fed to scanner  550 . A feed roller  566  may be rotateably engageable with a document in tray  565  and operable to pick a document from a plurality of documents supported by tray  565 . One or more guides  561  and  562 , or other structures, may define a document feed path through which a document is driven from input tray  565  to a scanner assembly outlet  567 . A document may be driven through outlet  567  by an imaging roller, a belt-drive assembly, or another apparatus. As a document is driven through outlet  567 , the document is positioned in contact with secondary scan platen  111  of scanner  550  whereupon an image portion of the document in contact therewith is scanned by the imaging assembly of scanner  550 . Accordingly, when imaging documents in the second operational mode, the imaging assembly remains stationary in a home position (X=0). Sequential image scan lines are captured by the imaging assembly as the document is driven past secondary scan platen  111 . As the document is driven past secondary scan platen  111 , an inclined portion  115 A of top surface  115  may direct the document through a cover assembly inlet  568  of cover assembly  560  and, as the document is rotateably engaged with one or more feed or imaging rollers, thereafter driven to an output tray (not shown) disposed on cover assembly  560 . While such a scanner and ADF configuration does not require a platen or other transparent surface to be included within cover assembly  570 , scanner  550  must be equipped with a secondary scan platen  111 . Inclusion of secondary scan platen  111  increases the overall manufacturing cost of scanner  550  and undesirably increases the requisite dimensions of scanner  550 . Moreover, a conventional ADF integrated within scanner cover assembly  570  has a propensity to “jam” during traversal of a scanned document through scanner assembly outlet  568 .  
     [0032] The present invention provides an ADF with a scan region defined by an opening, rather than a window, such that no ADF element or component is disposed in the scan region. Accordingly, no ADF component may become soiled and adversely effect the scan quality of documents fed thereby to a scanning device. Furthermore, engagement of an imaging roller with a document being scanned is delayed until a portion of the document has traversed a predefined position of an output element to alleviate jamming of the document during traversal thereby past a scan region of the scanner device.  
     [0033] The present invention may better be understood with reference now to FIGS.  8 A- 8 D. FIG. 8A is a schematic side view of one or more feed rollers  620  and one or more imaging rollers  630  in a configuration according to an embodiment of the present invention. One or more document guides may define a path along which a document  615  traverses when engaged with feed roller  620 . Thereafter, document  615  is forwarded along a document path towards a scan region  625  defined by an opening  685  (FIG. 8D) in a bottom surface  695  of an ADF chassis or frame that is adjacent a platen  610  on which the ADF is positioned. A scanning device may be positioned beneath platen  610  in such a manner to be optically coupled with the scan region (and, thus, a document portion situated within the scan region) and may image document  615  traversing scan region  625 . To facilitate proper positioning of document  615  within scan region  625  and to avert jamming of the document with a document guide, a first document guide  680  and a second document guide  681  may be configured to facilitate passage of an anterior edge  615 A of document  615  past a vertex  681 A (that is, a point of guide  681  generally characterized as an intersection of two surfaces  681 B and  681 C of guide  681 ) of document guide  681  prior to engagement of imaging roller  630  with document  615 . Preferably, document guide  680  comprises two intersecting surfaces  680 B and  680 C that define a vertex  680 A situated at a greater vertical disposition than vertex  681 A relative to a platen surface  610 A when document guides  680  and  681  are appropriately positioned adjacent platen  610  for performing a scan operation. For example, a stand-alone ADF featuring guides  680  and  681  may be considered to be in position for scanning a document when the ADF is positioned upright with a bottom surface thereof in contact with platen surface  610 A. Similarly, an ADF integrated in a scanner cover assembly may be considered to be in a position for performing a scan operation when the cover assembly is in a closed position such that a bottom surface of the cover assembly is in contact with a scanner platen surface  610 A. While vertices  680 A and  681 A illustrated are formed from intersecting surfaces of a respective guide  680  and  681 , alternative configurations of guides  680  and  681  are possible without departing from the present invention. For example, a first vertex of a document guide situated at a greater vertical disposition than a vertex of a second document guide may be formed by a single surface of a document guide and another surface or structure of the ADF. Likewise, the vertex of the second document guide may be formed from intersecting surfaces of the document guide or may alternatively be formed from intersecting surfaces of two or more ADF structures or a combination of intersecting surfaces of a document guide and other ADF structures.  
     [0034] The relative positions of vertices  680 A and  681 A facilitate driving document  615  through scan region  625  in such a manner that anterior edge  615 A may pass through scan region  625  and impinge guide  681  without coming in contact with platen  610  thereby avoiding a common cause of ADF jamming, as shown in a schematic side view of a feed roller  620  and an imaging roller  630  in a configuration of the present invention of FIG. 8B. In other words, anterior edge  615 A traverses scan region  625  and impinges guide  681  without intersecting a longitudinal plane (co-planar with a longitudinal axis  695 ) of opening  685 . After traversal by anterior edge  615 A through scan region  625  and impingement with guide  681 B, imaging roller  630  is preferably rotateably engaged with document  615  (FIG. 8C). For example, imaging roller  630  may be disposed within the ADF and may have a translational motion imparted thereto that directs imaging roller  630  into contact with document  615  and thus drives a portion of document  615  into abutment with platen  610  As described above, prior to engagement of imaging roller  630  with document  615 , an anterior edge  615 A has been driven past imaging roller and into impingement with guide  681 . Accordingly, initial contact between imaging roller  630  and document  615  is made at an portion of document  615  intermediate anterior edge  615 A and a posterior edge  615 B.  
     [0035] With reference now to FIGS. 9 and 10, there is respectively shown a side sectional schematic and a top sectional schematic of a stand-alone ADF  700  having an elongate opening  745  in a bottom surface  735  of a chassis  710  defining a scan region  725  in which one or more documents  715  may be scanned during traversal thereof according to an embodiment of the present invention. Scan region  725 , in general, corresponds to a region adjacent elongate opening  745  when device  700  is optically coupled to a scanner device  100  such that a scan operation may be performed on a document fed to scanner device  100  by device  700 . An input tray  750 , or another support, may support one or more documents  715  that may be sequentially fed past scan region  725 . One or more feed rollers  760  and  761 , or another component for extracting a document from input tray  750 , may have a rotational motion imparted thereto via one or more DC motors (not shown) or another power source. As a document  715 A is engaged by feed rollers  760  and  761 , a translational motion is imparted thereto that drives document  715 A along a document path defined by one or more guides  780 - 782 . As document  715 A approaches an imaging roller  770 , a position of document  715 A may be detected by one or more sensors  745  that detect the presence of document  715 A. For example, sensor  745  may be an optical sensor and configured to detect passage of a first predefined position within chassis  710  of an anterior edge  715 A 1  of document  715 . Sensor  745  may be coupled to one or more DC motors  765  operable to impart a rotational motion to imaging roller  770  that facilitates engagement of the document and drives the document past elongate opening  745 . DC motor  765  may be operable to impart a reciprocating translational motion to imaging roller  770  as well. Reciprocal translation of imaging roller  770  between a first position and a second position disposed vertically therebelow may be achieved by, for example, a cable and rotatable pulley coupling powered by a reversible DC motor and initiation of translation from a first position to a second position may be made upon detection of anterior edge  715 A 1  passing the first predefined position and is preferably timed so that an anterior edge  715 A 1  of document  715 A passes through scan region  725  and impinges guide  781  prior to engagement of imaging roller  770  with document  715 A. Moreover, it is preferable that guide  780  provides a vertex  780 A situated at a greater vertical disposition than another vertex  781 A provided by guide  781  relative to a platen surface  110 A. Exemplary vertices  780 A and  781 A are formed at a structural intersection of guide  780  with bottom surface  735  and a structural intersection of guide  781  with bottom surface  735 . Accordingly, document  715 A may be driven along the feed path defined by guide  780  and imparted into scan region  725  with sufficient trajectory that anterior edge  715 A 1  passes through scan region  725  and impinges guide  781  without contacting platen surface  110 A. Thus, a common cause of jamming of a document with a vertex or other edge of a document guide is averted. Upon detection of document  715 A, sensor  745  may provide an electrical signal to motor  765  and, thereafter, motor  765  may perform a first actuation of one or more linkages, gears, transmission drives or other physical couplings such that a translational motion is imparted upon imaging roller  770  that directs imaging roller toward elongate opening  745  aligned along a transverse axis  755  in bottom surface  735  of chassis  710 . Actuation of any translational motion imparted to imaging roller  770  may be timed such that a portion of document  715 A has traversed at least a portion of scan region  725  so that anterior edge  715 A 1  has traversed scan region  725  (and thus elongate opening  745 ) and impinged a guide  781 , or other structure, prior to engagement therewith by imaging roller  770 . Thereafter, physical engagement between imaging roller  770  and a portion of document  715 A intermediate anterior edge  715 A 1  and posterior edge  715 A 2  is made. Accordingly, upon completion of the first actuation, imaging roller  770  is positioned such that a portion of document  715  at least partially disposed within scan region  725  will abut platen  110  of reflective scanner  100  physically adjacent bottom surface  735  of ADF  700 . Sensor  745  may be configured to detect passage by a second predefined position within chassis  710  of a posterior edge  715 A 2  of document  715 A and, upon detection thereof, convey such detection to motor  765 . The second predefined position may be identical to, or disposed at a different position, within chassis  710  respective the first predefined position. Thereafter, motor  765  may impart a translational motion to imaging roller  770  such that imaging roller  770  is returned to the first vertical position from the second vertical position.  
     [0036] An output tray  740 , or another support for receiving the document after the document is driven past elongate opening  745  may be disposed within chassis  710 , or on a surface thereof, for reception of a scanned document. An output roller  795  may be rotationally engageable with document  715 A and facilitate delivery thereof into output tray  740 . Output roller  795  may be disposed within chassis in a position such that engagement with document  715 A is performed upon traversal of anterior edge  715 A 1  past elongate opening  745 .  
     [0037] As described, a system and method for automatically feeding documents to a scanning device is provided. The device of the present invention does not comprise a scan window, or other transparent structure, and accordingly is not subject to scan quality degradation as is common in conventional automatic document feeders. Furthermore, the device may be integrated within a scanner cover assembly and does not require inclusion of a separate window for facilitating scanning by the automatic document feeder. Moreover, the technique of the present invention for feeding documents comprises positioning two guide structures in such a manner so that a trajectory imparted to a document through a scan region may be sufficient to ensure that an anterior edge of the document does not come into contact with the scanner platen, thereby avoiding a common cause of document jamming.