Abstract:
A method and apparatus of processing sheet media such as document sheets to be duplex scanned or media sheets on which two sided printing is to take place includes automatic positioning of an active sheet guide gate and drag clutch by the rotation of a transport roller with which the active gate and drag clutch is frictionally engaged. The transport roller may comprise one or more coaxial rollers in an assembly positioned in the media path and is rotatable in different directions such that the leading edge of a moving media sheet is moved through one or the other of two nips defined between the transport roller assembly and associated upper and lower pinch rollers. The direction of rotation of the transport roller assembly can be reversed before the sheet leaves the nip to thus re-position the sheet guide gate and re-route the sheet back in a desired path to a scanner or printer for further sheet processing.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS, IF ANY 
     None. 
     BACKGROUND OF THE INVENTION AND PRIOR ART 
     The present invention relates to the transport of individual cut sheets of flat flexible media such as paper, vellum, transparencies or the like through a transport path which may have various branches for the delivery of sheets such as printed sheets of media from an input location to a desired location. For the purposes of illustration but not limitation, the invention will be described in the context of a document scanning apparatus having a sheet transport path which extends from a stack of document sheets to be scanned to and through a scanning location to a scanned document location where the scanned sheets are stacked. More particularly, the invention is concerned with the guiding and movement of sheets in a scanning apparatus or printer capable of duplex scanning or printing wherein one side of a media sheet is first scanned or printed and then, if desired, the individual sheets may then be turned over and routed back to the scanning or printing region for scanning or printing the other side of the sheet. The teachings of the invention are applicable generally to any office or business machine in which flexible media sheets must be moved to selected paths. 
     As used herein, the term “sheet processing apparatus” is therefore intended to broadly include, but not necessarily be limited to, printers, stand alone document copiers, facsimile machines, document scanning machines and combinations of such units. 
     SUMMARY OF THE INVENTION 
     The present invention provides a method of processing sheet media in a sheet processing apparatus comprising the steps of: 
     a) moving individual media sheets from a first location to a processing location in said sheet processing apparatus; 
     b) processing a first face side of a media sheet at said processing location; 
     c) moving said sheet from said processing location into a sheet guide channel in a pivotally mounted active gate extending across a media path; 
     d) rotating a sheet transport roller in a selected direction to cause said roller to frictionally engage and pivotally move said gate to a first position in which said guide channel is aligned with one of two nips extending to spaced sheet delivery paths; and 
     e) gripping said sheet in a selected one of said nips and rotating said transport roller in a direction to transport said sheet away from said processing location through said guide channel into one of said spaced sheet delivery paths. 
     In apparatus terms, the present invention comprises a sheet media processing apparatus which includes: 
     a) a sheet media input support; 
     b) a sheet media processor; 
     c) a processed sheet media support; 
     d) sheet guides defining a media transport path extending from said input support past said processor to said processed sheet media support; 
     e) sheet transport means for moving individual media sheets along said path; and 
     f) an active sheet routing gate and drag clutch which includes a sheet routing channel which is moveable in said media transport path in a space between an input and first and second output branches; said sheet transport means including a driven sheet transport roller and a power drive for rotating said transport roller in opposite directions to move said leading edge of said sheet along a selected output branch, said gate and drag clutch being engaged with said transport roller to move said sheet routing channel to extend from said input toward a selected one of said first and second output branches. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 a  and  1   b  are side elevation views of a document scanning apparatus which incorporates the teachings of the present invention including an active sheet routing gate and drag clutch, the gate being in a lower position if FIG. 1 a  and in an upper position in FIG. 1 b.    
     FIGS. 2 a  and  2   b  are perspective views of a transport roller assembly comprised of a series of spaced coaxially arranged sheet drive rollers and pinch rollers with the active gate and drag clutch engaged with the transport rollers at each end of the assembly at the sides of a sheet media path, the gate being in a lower position in FIG. 2 a  and in an upper position in FIG. 2 b.    
     FIGS. 3 a  and  3   b  are enlarged schematic side elevation views, partly in cross section, of the active sheet routing gate and drag clutch operating in conjunction with the reversible sheet transport output roller assembly. 
     FIGS. 4 a - 4   d  are side elevation views sequentially showing the progress of a media sheet through the document scanning apparatus. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in the drawings, a document scanning apparatus  10  includes a generally flat horizontally extending glass table or platen surface  12  for single sheet scanned having a region  14  at one end thereof through which a moving document to be scanned can be viewed by conventional document scanning components of the device. An inclined frame  20  is provided for supporting a stack  24  of documents to be fed to the scanning components. An inclined surface or guide  26  on the frame  20  and stationary media sheet guides  27 ,  28  on the frame together define a sheet media path extending from the media stack  24  to the scan region  14  and thence around a scanning roller  40  and document output sheet transport roller assembly  50  to a scanned document output location at which a tray  34  is provided for receiving a stack of scanned documents. Circumferentially spaced pinch rollers  42  hold the document sheet against the scanning roller. The apparatus for feeding individual sheets from the stack  24  to the scan region  14  includes the inclined media support or feed tray  22 , upper and lower opposed media pick rollers  30 ,  32  and a suitable drive mechanism for moving the rollers  30 ,  32 . The drive mechanism may be arranged to drive the rollers  30 ,  32  in the same forward direction of rotation (e.g., clockwise) for uppermost sheet picking and in the same reverse direction (e.g., counterclockwise) for lowermost sheet picking as described in commonly owned co-pending application Ser. No. 09/405,991 (HP Docket 10991829-1) filed Sep. 27, 1999. 
     FIGS. 2 a  and  2   b  respectively show perspective views of a transport roller assembly  50  comprised of a rotatable shaft  52  having a plurality of sheet transport rollers  54  affixed thereto at axially spaced locations along the shaft  52 . Each of the rollers  54  is preferably identical to the other rollers  54  and has a rubberized or other frictional surface. As used herein, the term “roller” is intended to include a single elongated roller and the mechanical equivalents of two or more axially spaced rollers on a common shaft or axis as shown. The transport roller assembly may be molded of plastic with a plurality of elongated ribs  70  and circumferential rings  72  to provide support as necessary to the media sheet. 
     Pinch rollers  62  and  64  are respectively positioned above and below the transport roller assembly  50  and tangentially engage the rollers  54  to provide nips and media sheet delivery paths above and below the transport roller assembly  50 . Only the upper pinch rollers  62  are shown in the perspective views of FIGS. 2 a  and  2   b  but the lower rollers  64  are also seen in FIGS. 1 a  and  1   b  as well as in FIGS. 3 and 4. The lower pinch rollers  64  are, like the upper pinch rollers  62 , engaged tangentially with selected ones of the transport rollers  54 . Preferably, the pinch rollers  62 ,  64  are c on diametrically opposite sides of the transport roller assembly  50  although it is not essential to do so. A suitable power drive, not shown, is provided for rotating the transport roller assembly  50  in either the clockwise or the counterclockwise direction as desired. 
     Since rollers  54  are primarily used for transporting the sheet of media through nips defined between the rollers  54  and the pinch rollers  62 ,  64 , preferably all of the transport rollers  54  and pinch rollers  62 ,  64  are provided with traction surfaces suitable for gripping and transporting media sheets through the nips as is conventional. The pinch rollers  62 ,  64  may be spring biased into engagement with the transport rollers  54  and comprise idlers which are only rotatable when the power driven transport roller assembly  50  is rotated. The opposed drive and pinch rollers  54 ,  62 ,  64  in surface contact provide one way of defining sheet transport nips as is well known; however, in the context of referring top nips defined by rollers, the term “roller” is also intended and specifically defined to include mechanical substitutes having opposed surfaces which define nips such as opposed continuous belts trained around rollers or an opposed roller and belt which together define a nip. 
     An active gate and drag clutch  70  best seen in FIGS. 2 a  and  2   b  is located in a space in the media transport path between an input to the gate and clutch  70  from the document drive roller  40  and first and second media output branches above and below the transport roller assembly  50 . The active gate and clutch  70  is comprised of a pair of end plates  72 ,  74  rotatable about a common axis  76  which extends parallel to shaft  52 . The document path between the end plates  72 ,  74  of the active gate and drag clutch  70  is bridged by upper and lower sheet guides  80 ,  90  of plastic or light weight sheet metal affixed to the end plates whereby the guides  80 ,  90  define a sheet routing or guide channel  82  (FIG. 3) therebetween for guiding the leading edge of a sheet from the top surface of the document drive roller  40  to either one of a lower nip or nips between the document delivery roller or rollers  54  and the lower pinch rollers  64  or to an upper nip between the document delivery roller or rollers  54  and the upper pinch rollers  62  depending upon the position of the gate and drag clutch  70 . An arcuate side edge  78  on each end plate  72 ,  74  frictionally engages the cylindrical surface of the axially outermost transport rollers  54  or other similarly moveable portions of the transport roller assembly  50  such that rotation of the transport roller assembly  50  including the rollers  54  determines the position of the active gate and drag clutch  70 . Clockwise rotation of shaft  52  causes counterclockwise pivotal motion of gate  70  about its axis  76  until gate  70  reaches its uppermost limit position shown in FIGS. 1 b ,  2   b  and  3   b  following which slippage between the arcuate surfaces  78  of the gate end plates and the transport rollers  54  holds the active gate  70  in the selected position. Gate motion limit stops (not shown) are provided at the desired locations on the scanning apparatus to limit the motion of the gate and drag clutch  70  between the positions shown in FIGS. 1 a  and  1   b . The lower sheet guide  90  includes a lower portion  92  as shown for a purpose which will be described with reference to FIG.  4 . 
     FIG. 4 a  shows the initial movement of a sheet of paper or other media from the top or bottom of the stack  24  by the opposed pick rollers  30 ,  32 . In the position shown in FIG. 4 a , the leading edge of the sheet has been driven by the document drive roller  40  through the sheet processing location  14 , the leading edge of the sheet having reached a location in the sheet guide channel  82  between the gate sheet guides  80 ,  90 . As the leading edge of the sheet, moved by the document drive roller  40  approaches the active gate  70 , but before it enters channel  82 , a timing circuit actuates the power drive to cause rotation of the transport roller assembly  50  in the counterclockwise direction as seen in FIG. 4 a  to move the gate  70  to its downward position. Continued movement of the leading edge of the media sheet causes the leading edge to enter the lower nip or nips between the transport rollers  54  and the lower pinch rollers  62  to transport the leading edge of the sheet through the channel  82  into the lower output path between the stationary guide  27  and transport roller assembly  50 . The rotation of the nip between the sheet transport roller or rollers  54  and the lower pinch rollers  64  continues to move the sheet to the right below the transport roller assembly  50  thus causing the trailing portion of the sheet to move entirely through and away from the processing location  14  and document drive roller  40  toward the processed sheet location or tray  34  as seen in FIG. 4 b.    
     In FIG. 4 c  the direction of rotation of the transport roller assembly  50  is reversed such that the roller assembly  50  now begins to rotate in a clockwise direction before the trailing edge of the sheet has passed the nip between the transport rollers  54  and lower pinch rollers  64  from the sheet position seen in FIG. 4 b . This causes the sheet to move back toward the processing location  14  in face inverted orientation so that the other face side of the document sheet can now be scanned or printed upon. Clockwise rotation of the transport roller assembly  50  causes movement of the active gate and drag clutch  70  to the upper position seen in FIG. 4 c . this causes movement of the lower portion  92  of the lower gate guide  90  to a position spaced from and generally parallel to stationary guide  27  to guide the sheet back to the document drive roller  40 . During scanning or printing of the second face side of the sheet, the document drive roller  40  continues to rotate in the clockwise direction moving the sheet through the sheet processing region  14  until the leading edge of the sheet (previously the trailing edge) enters the guide channel  82  between the gate guides  80 ,  90  and moves into the nip or nips between the transport roller or rollers  54  and upper pinch rollers  62  so that the document sheet, now having been duplex scanned or printed, may be passed over the transport roller assembly  50  to the tray  34 . 
     In its broadest aspects, the invention involves the use of the active gate and drag clutch  70  to guide the leading edge of a moving media sheet to one of two output paths which, in the arrangement shown, are above and below the transport roller assembly  50 . There is of course no reason that these teachings need be limited to a horizontally oriented transport roller assembly  50  since the principles of the invention will clearly be applicable to the handling of sheet media moving with its flat surfaces in a non-horizontal path provided that appropriate minor modifications are made. In the preferred embodiment shown, separate transport rollers  54  and associated pinch rollers  62 ,  64  transport the sheet past the transport roller assembly  50  on the selected upper or lower side depending upon the direction of rotation of the transport roller assembly  50 . 
     The active sheet guide gate and drag clutch  70  can be molded or otherwise fabricated of plastics or other light weight materials. The details of a suitable drive arrangement for rotating the roller assembly  50  in the desired directions of rotation at the desired time are well within the skill of persons skilled in the art and is therefore not described herein. Persons skilled in the art will also appreciate that various additional modifications can be made in the preferred embodiment shown and described above and that the scope of protection is limited only by the wording of the claims which follow.