Abstract:
A print media handling system for an imaging apparatus having a media feed path includes a pair of media support members, each have a first wall defining a media contact surface and a support portion defining a media support surface. The pair of media support members are pivotally mounted to the imaging apparatus for symmetrical operation with respect to a centerline of the media feed path. The pair of media support members define a media bin for receiving printed media. The print media handling system further includes a drive system for operating the pair of media support members between a first position wherein the media support surface of the pair of support members carries a printed media sheet and a second position wherein the printed media sheet is released to fall into the media bin. The drive system further controls the pair of media support members such that the contact surface of each of the pair of media support members contacts opposing edges of the printed media to align the printed media in the media bin.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a printing system, and more particularly, to a print media handling system and associated method. 
     2. Description of the Related Art 
     In a typical ink jet printer, print media is directed through a print cycle which includes picking a media sheet from an input tray, transporting the media sheet through a printing zone for printing, and then transporting the printed sheet through an output port. Once the printed sheet exits the output port, the printed sheet is received by an output tray. Consecutive printed sheets are piled one on top of another as successive sheets are printed to form an output stack. Since ink jet printers print with a liquid ink, and because sheets often are stacked immediately after printing, ink jet printers have in the past experienced some difficulty with smearing of ink upon contact of a previously printed sheet by an immediately subsequent printed sheet. This has been particularly apparent where ink drying time exceeds the time between the printing of consecutive sheets. 
     A variety of approaches have been used in attempting to deal with this problem. For example, some manufactures have attempted to eliminate ink smearing problems by decreasing ink drying time by employed quick-drying ink, or specially-coated paper, often resulting in poorer quality print. Also, some manufacturers have incorporated a drying lamp or heater in the printer near the printed media sheet, thus adding to the complexity of the printer, and consequently adding to the printer&#39;s price. Still other manufacturers have attempted to delay the delivery of printed sheets to the output tray so as to provide the previously printed sheet with adequate drying time. 
     One such an attempt to delay the delivery of printed sheets to the output tray so as to provide the previously printed sheet with adequate drying time is to use a passive sheet media drop scheme, whereby a printed sheet exiting the printer&#39;s output port is guided along rails which temporarily support the sheet above the output tray. Upon completion of printing, the sheet drops under the effect of gravity into the output tray, thereby allowing the previously printed sheet sufficient time to dry during printing of the present sheet. One problem associated with such a passive system, however, is the inability to adapt its operation to various printing environments or when a large quantity of ink is deposited on the printed sheet. 
     One solution to the problems associated with such a passive system is to provide an active sheet media delivery mechanism, wherein a printed sheet is guided along a pair of movable rails which temporarily support the sheet above the printer&#39;s output tray while the previously printed sheet drys. Once printing is completed, the rails retract, often pivotally, allowing the sheet to fall to an output tray below. Although generally effective, active drop mechanisms generally have presented problems due to permitting the skewing of sheets in the output tray, and as a result, generally pose limitations on output tray capacity. In addition, such active sheet media delivery mechanisms are driven cyclically by the same drive which drives the paper feed, thereby limiting operating adaptability. 
     SUMMARY OF THE INVENTION 
     The present invention provides, for example and not by way of limitation, an active sheet media delivery system and method which is driven independent of the paper feed drive, and which provides for the correcting of random skewing of multiple printed sheets as the sheets are accumulated in an output bin. 
     The invention comprises, in one form thereof, a print media handling system for an imaging apparatus having a media feed path, and a pair of media support members, each have a first wall defining a media contact surface and a support portion defining a media support surface. The pair of media support members are pivotally mounted to the imaging apparatus for symmetrical operation with respect to a centerline of the media feed path. The pair of media support members define a media bin for receiving printed media. The print media handling system further includes a drive system for operating the pair of media support members between a first position wherein the media support surface of the pair of support members carries a printed media sheet and a second position wherein the printed media sheet is released to fall into the media bin. The drive system further controls the pair of media support members such that the contact surface of each of the pair of media support members contacts opposing edges of the printed media to align the printed media in the media bin. In a preferred embodiment of the invention, the control system controls the pair of media support members to tap opposing edges of the printed media accumulated in the media bin on an intermittent basis, regardless of the presence of a printed sheet of media at the media support surface of each of the pair of media support members. 
     One advantage of the present invention is that the printed media support members are driven independent of the drive used to feed a media sheet through the printer. Still another advantage is the ability to use the media support members to contact, e.g., by tapping or squeezing, the longitudinal edges of the printed sheets accumulated in the output bin to vertically align the accumulated sheets, and thus avoid random skewing of individual sheets of the multiple printed sheets as the sheets are accumulated in the output bin. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is partial perspective view of a printer including the present invention; 
     FIG. 2 is perspective view of a winged support member of the present invention;. 
     FIG. 3 is a schematic illustration of a control system of the present invention; and 
     FIG. 4 is partial perspective view of the printer if FIG. 1, wherein the winged support members are in a media drop position. 
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings and particularly to FIG. 1, there is shown a portion of a printer  10 , which includes a printer frame  12 , a print cartridge carrier assembly  14 , a maintenance assembly  16  and an active print media handling mechanism  18 . Print media handling mechanism  18  is shown in the media support position with a media sheet S (shown by phantom lines) being supported thereby. 
     Printer frame  12  includes two side frames  20 , only one of which is shown, a middle frame  22  and an end wall  23 . Middle frame  22  is mounted between the two side frames  20  and has an end portion  24  and an upper surface  26 . End portion  24  defines an exit port of printer  10 , and upper surface  26  defines the lower side of a media feed path  28 . Each media sheet is advanced through the printer media path  28  by opposing pairs of feed rolls (not shown) in a conventional manner. Middle frame  22  is provided with a plurality of holes  30  so that feed rolls located below the frame may coact with feed rolls above the frame to feed the media sheet along upper surface  26  of middle frame  22 . Middle frame  22  is further equipped with an exit assembly including exit rollers  31  positioned near end portion  24  for transporting the printed sheets out of exit port  24 . A detachable guide rod  32  is supported by and extends between the two side frames  20 , and further extends transverse to the media sheet feed direction, indicated by arrow  33 , and is located above media feed path  28  for supporting carrier assembly  14 . 
     Carrier assembly  14  includes slide bearings  34  housed within two bearing housings  36  which slidably receive guide rod  32 . Carrier assembly  14  includes two sets of belt gripper jaws  38 . Gripper jaws  38 , together with a belt (not shown), are driven by a bi-directional motor (not shown) which moves carrier assembly  14  and an associated print cartridge  40  back and forth along guide rod  32 . 
     Maintenance assembly  16  includes a wiper  42  and capping unit  44 . Wiper  42  is used for cleaning a nozzle plate (not shown) of print cartridge  40  . Capping unit  44  is used to provide a seal around the nozzle plate during periods of non-use to prevent the ink which accumulates in the nozzles of the nozzle plate from drying and clogging the nozzle openings. A maintenance cycle is effected in a known manner by transporting carrier assembly  14  along guide rod  32  until the nozzle plate of print cartridge  40  is wiped by wiper  42 . At the end of a printing cycle, carrier assembly  14  is transported along guide rod  32  until the nozzle plate of print cartridge  40  approaches the capping unit, and then capping unit  44  is raised to cap the nozzle plate. 
     As shown in FIG. 1, a portion of printer frame  12  is broken away to more clearly view active media handling mechanism  18 . Active media handling mechanism  18  is attached to printer frame  12  to receive printed sheets which are expelled from exit port  24 . Media handling mechanism  18  includes a pair of winged support assemblies  46   a,    46   b,  which define a media bin  48 . The surface on which printer  10  rests can serve as a bottom of media bin  48 , or alternatively, an optional media base  49  may be used. Winged support assemblies  46   a,    46   b  are pivotally attached to end wall  23  of printer frame  12 , and are symmetrically arranged and spaced apart from a centerline  50  of media feed path  28 . Optional tray base  49  is adapted for attachment to printer frame  12 . 
     Winged support assembly  46   a  includes a pivot axle  52   a,  a media support member  54   a,  a frame bushing  56   a  and a cam follower linkage  58   a.  Likewise, winged support assembly  46   b  includes a pivot axle  52   b,  a media support member  54   b,  a frame bushing  56   a  and a cam follower linkage  58   b.    
     Pivot axles  52   a,    52   b  have a D-shaped cross section shape, and media support members  54   a,    54   b  include apertures  60   a,    60   b,  respectively, having a corresponding “D” shape. Thus, the cross section shape of pivot axles  52   a,    52   b  facilitates axial slidable coupling to media support members  54   a,    54   b,  respectively, and further facilitates the radial drive of media support members  54   a,    54   b,  respectively, relative to the axial extent of pivot axles  52   a,    52   b.  Frame bushings  56   a,    56   b  are attached to pivot axles  52   a,    52   b,  respectively, near the driven ends  62  thereof, and are rotatably mounted to end wall  23  of printer frame  12 , to thereby pivotally mount media support members  54   a,    54   b  to printer frame  12 . A cam follower linkage  58   a,    58   b,  is attached to driven ends  62  of pivot axles  52   a,    52   b,  respectively. 
     FIG. 2 shows a detailed view of winged support assembly  46   b  separated from printer frame  12 . Winged support assembly  46   b  is symmetrically identical to winged support assembly  46   a.  Accordingly, only winged support assembly  46   b  will be discussed in detail for simplicity of discussion and ease of understanding. It is to be understood that the discussion which follows regarding winged support assembly  46   b  and media support member  54   b  also applies to winged support assembly  46   a  and media support member  54   a.  Media support member  54   b  of winged support assembly  46   b  includes a mounting portion  64 , a joining wall portion  66  and a media support portion  68 . Joining wall portion  66  integrally connects mounting portion  64  to media support portion  68 . Mounting portion  64  extends outwardly and upwardly from pivot axle  52   b  to form a terminating end  70 . Joining portion  66  extends upwardly from terminating end  70  to form an upper end  72 , and is maintained in a substantially vertical orientation when print media handling mechanism  18  is in a media sheet support, or receiving, position (see FIG.  1 ). Media support portion  68  extends inwardly away from upper end  72  to form a support end  74 . 
     Joining wall portion  66  includes a contact surface  78  which is used by printer  10  to lightly contact, e.g., by tapping or squeezing, the longitudinal edges of accumulated printed sheets to vertically align the accumulated sheets in media bin  48 . Media support portion  68  includes a wing surface  80  which provides temporary support for a printed sheet after it is initially received by print media handling mechanism  18 . 
     Cam follower linkage  58   b  extends perpendicularly away from pivot axle  52   b.  A cam follower  82  extends from cam follower linkage  58   b  in a direction parallel to the axial extent of pivot axle  52   b.  A length L of cam follower  58   b  linkage is defined by the distance of separation between an axis of rotation of pivot axle  52   b  and an axis of the axial extent of cam follower  82 . 
     FIG. 3 illustrates by perspective view and partial schematic a control system  84  which operates and controls the operation of media handling mechanism  18 . Control system  84  includes a drive shaft assembly  86 , a stepper motor  88 , a stepper motor controller  90  and an input device  92 . In FIG. 3, only the drive for the left winged support assembly  46   b  is shown for simplicity of discussion and ease of understanding, however, it is to be understood that the discussion that follows also applies to the mechanism which provides driving force to right winged support assembly  46   a.  The terms “left” and “right” are relative terms and define the orientation of components as they appear in FIG.  1 . 
     Drive shaft assembly  86  includes a drive shaft  94 , a driven gear  96 , a media handling cam  98  and, optionally, auxiliary cams  100 . Media handling cam  98  is attached to drive shaft  94  at a location such that when drive shaft assembly  86  is installed in printer  10 , the various cam surfaces  102  and  104  of cam  98  can engage cam follower  82 . Auxiliary cams  100 , and sensor flags, may be used to drive auxiliary printer equipment which can operate on the same operation cycle as print media handling mechanism  18 . Driven gear  96  is also attached to drive shaft  94  and includes teeth which mesh with the teeth of a drive gear  108  of stepper motor  88 . Stepper motor  88  is electrically coupled via conductor  1   10  to stepper motor controller  90 , which in turn is coupled via conductor  112  to input device  92 . 
     Input device  92  can be, for example, a printer controller of printer  10  which processes information relevant to the operation of printer  10 , and which provides control outputs to the various operational units of printer  10 , including for example, a media sheet feed, the print engine, and media handling mechanism  18 . With respect to media handling mechanism, the information can include, for example, ambient environment information, media sheet positional information and ink drying information. Alternatively, input device  92  can include a sensor located in the media sheet feed path to detect the delivery of media sheet S to media handling mechanism  18 , and/or ambient conditions, and associated logic for processing output from the sensor. 
     Input device  92  generates a stepper motor control signal based on received information, which is supplied to stepper motor  90 . The stepper motor control signal may result in the operation of stepper motor  90  at regular intervals, depending upon the sheet stacking conditions of media bin  48 . Stepper motor  90  rotates drive gear  108  in a predefined direction to effect a rotation of drive shaft  94  in a counter-clockwise direction indicated by arrow  114 , or in a clockwise direction as indicated by arrow  115 . As shaft  94  rotates, cam follower  82  traverses the cam surface regions  102  and  104 . 
     A spring  120  maintains cam follower  82  in contact with cam  98 . Thus, spring  120  biases winged support assembly  46   b  inwardly, toward centerline  50  of media path  28 . While spring  120  is shown connected to “ground”, in which two springs  120  would be required to bias winged support assemblies  46   a,    46   b,  a single spring could be used which is connected between winged support assemblies  46   a,    46   b.    
     When cam follower  82  is present in cam region  102 , no rotational motion, or displacement is applied to pivot axle  52   b.  The angular extent of cam region  102  may be selected to provide the desired amount of delay from the time drive axle  114  begins rotating until the time follower  82  reaches the beginning of transitional cam region  104 . 
     As cam follower  82  traverses transitional cam region  104  as a result of the rotation of drive shaft  94  in the direction  114 , a rotational motion, or displacement, is applied to pivot axle  52   b  resulting in a rotation of pivot axle  52   b  in a direction depicted by arrow  116 . The cam profile of transitional cam surface  104  will influence the amount and rate of rotation of pivot axle  52   b.  For example, a distance D represents the maximum lateral extent  118 , or lift, of transitional cam region  104  from cam region  102 , which along with a length L of cam follower linkage  58   b,  determines the amount of pivotal rotation of pivot axle  52   b  in direction  116 . The rotational point-to-point extent of transitional cam region  104  from the junction of cam surface portions  102  and  104  to maximum lateral extent  118 , and the rate of rotation of drive shaft  94 , determines a rate of rotation of pivot axle  52   b.    
     Preferably, cam follower  82  does not traverse maximum lateral extent  118  to contact surface  106 . Rather, the direction of rotation of drive shaft  94  is reversed, as depicted by arow  115 , which in turn effects rotation of pivot axle  52   b  in the direction depicted by arrow  122 , so that cam follower  82  travels back down transitional cam region  104  toward cam surface  102 . 
     The operation of print media handling mechanism  18  of printer  10  will now be described with reference to FIGS. 1-4. 
     Referring now to FIG. 1, printing takes place in a conventional manner. As a media sheets is fed under print cartridge  40  in the direction of arrow  33 , print cartridge carrier assembly  14  is moved back and forth over the media sheet S as ink within print cartridge  40  is ejected from the nozzles. Data to be printed is received by the printer controller which converts or reformats the data and sends electrical signals to print cartridge  40  to control ejection of ink from the nozzle plate. The controller commands media sheet S to be expelled out of exit port  24 , and the expelled media sheet S is received by active print handling mechanism  18 . 
     As shown in FIG. 1, print handling mechanism  18  is oriented in the sheet support position, and thus, the media sheet S is positioned on winged support assemblies  46   a,    46   b  with a non-printed side of sheet S contacting and being supported by wing surfaces  80  of media support portions  68  of winged support assemblies  46   a,    46   b.  At this time, cam followers  82  of each of winged support assemblies  46   a,    46   b  are in contact with respective cam surfaces  102 . Preferably, the curvature of support surfaces  80  is centered on respective pivot shaft  52   a,    52   b  so that sheet S is not lifted as wing support assemblies  46   a,    46   b  are rotated to the media drop position. 
     Referring now to FIGS. 2 and 3, at a prescribed time following the receipt of media sheet S by print media handling mechanism  18 , input device  92  generates a stepper motor control signal, which is supplied to stepper motor  90  via conductor  112 . Stepper motor  90  then rotates drive gear  108  in a predefined manner to effect a rotation of drive shaft  94  in the direction indicated by arrow  114 . As shaft  94  rotates, cam follower  82  traverses the various cam surface regions  102 ,  104  of media handling cam  98 . 
     When respective cam followers  82  are present in respective cam regions  102 , and drive shaft  94  is rotated, no rotational displacement is applied to pivot axles  52   a,    52   b,  and print handling mechanism  18  remains in the sheet support position. As respective cam followers  82  reach respective transitional cam regions  104 , a rotational displacement is applied to pivot axles  52   a,    52   b  resulting in a rotation of pivot axles  52   a,    52   b  in opposing rotational directions. In turn, winged support assemblies  46   a,    46   b,  which are spring biased toward centerline  50 , begin to rotate away from centerline  50  to increase the spacing between the support ends  74  of media support members  54   a,    54   b.    
     FIG. 4 shows a partial front perspective view of printer  10 , and illustrates print media handling system  18  in the media drop position, and with winged support assemblies  46   a,    46   b  positioned at their greatest extent of spacing between support ends  74 . This greatest extent of spacing needs only be sufficient to permit a printed sheet to fall into media bin  48 . As cam follower  82  traverses transitional cam region  104 , the spacing between support ends  74  of media support members  54   a,    54   b  continues to increase, and ultimately sheet S falls by the effects of gravity into media bin  48  to join the plurality of printed sheets PS already contained therein. 
     Referring again to FIG. 3, at this time the rotational direction of drive axle  94  is reversed to rotate in direction  15 , and respective cam followers  82  traverses back down transitional cam surfaces  104 . Thus, cam followers  82  travel from maximum lateral extent  118  back to cam surfaces  102  to effect a reverse pivotal rotation of pivot axles  52   a    52   b,  and in turn winged support assemblies  46   a,    46   b  move toward media path centerline  50  to decrease the spacing between the support ends  74  of media support members  54   a,    54   b.  As media support members  54   a,    54   b  are returned to the media support position, contact surfaces  78  (see FIG. 4) of media support members  54   a,    54   b  contact, e.g., lightly tap, the longitudinal edges of the printed sheets accumulated in media bin  48  to vertically align the accumulated sheets. 
     Preferably, print media handling system  18  is controlled independently from the media sheet feed of printer  10 , such that movement of print handling mechanism  18  between the sheet support position and the media drop position is not dependent upon the status of the media sheet feed of printer  10 . Thus, print handling mechanism  18  can be cycled through the sheet support position and the media drop position regardless of whether a media sheet is present on wing surfaces  80  of media support members  54   a,    54   b,  thereby effecting the intermittent contact of contact surfaces  78  with opposing longitudinal edges of the accumulated sheets to further enhance the alignment of the printed sheets in bin  48 . This intermittent contact, e.g., tapping or squeezing, can be effected by input device  92  and/or stepper motor controller  90  to occur at either regular intervals or irregular intervals, depending upon the sheet stacking conditions of media bin  48 . Also, media handling mechanism  18  can be maintained in the media drop position by ceasing rotation of drive shaft  94  at the appropriate time. 
     By contacting, e.g., tapping or squeezing, the opposing longitudinal edges of the printed sheets accumulated in bin  48 , the vertically alignment of the accumulated sheets is improved and the effective capacity of media bin  48  is increased. 
     While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.