Title:
PREFLIPPING SHEETS FOR A DUPLEX OPERATION
Kind Code:
A1


Abstract:
A method for feeding sheets includes feeding a first sheet to a location for flipping sheets with respect to a target position before the first sheet is fed passed the target position. A second face of the first sheet is fed passed the target position. The first sheet is fed to a second location for flipping sheets with respect to the target position. The second location is different than the first location. A first face of the first sheet is fed passed the target position.



Inventors:
Foote, Wayne E. (Eagle, ID, US)
Application Number:
11/740521
Publication Date:
10/30/2008
Filing Date:
04/26/2007
Primary Class:
Other Classes:
700/44
International Classes:
B65H7/02
View Patent Images:



Primary Examiner:
CICCHINO, PATRICK D
Attorney, Agent or Firm:
HP Inc. (Fort Collins, CO, US)
Claims:
What is claimed is:

1. A method for feeding sheets, comprising: feeding a first sheet to a location for flipping sheets with respect to a target position before the first sheet is fed passed the target position; feeding a second face of the first sheet passed the target position; feeding the first sheet to a second location for flipping sheets with respect to the target position, the second location being different than the first location; and feeding a first face of the first sheet passed the target position.

2. The method of claim 1, wherein the acts of feeding are performed following receipt of an instruction for a duplex operation, the method further comprising, following receipt of an instruction for a simplex operation, feeding the first face of the first sheet passed the target position without feeding the first sheet to the first location for flipping sheets with respect to the target position.

3. The method of claim 1, further comprising outputting the first sheet after feeding the first face of the first sheet passed the target position.

4. The method of claim 1, further comprising: feeding a second sheet to the first location for flipping sheets before first face of the first sheet has been fully fed passed the target position; and after the first face of the first sheet has been fully fed passed the target position, feeding a second face of the second sheet passed the target position, feeding the second sheet to the second location for flipping media sheets, and feeding a first face of the second media sheet passed the target position.

5. The method of claim 1, further comprising: sequentially feeding each of a plurality of subsequent sheet to the first location for flipping sheets; for each subsequent sheet fed to the first position for flipping sheets, feeding a second face of that sheet passed the target position, feeding that sheet to the second location for flipping media sheets, and feeding a first face of that sheet passed the target position; wherein each subsequent sheet is fed to the first location for flipping sheets before the first face an immediately prior has been fully fed passed the target position and wherein the first face of that subsequent sheet is fed passed the target position after the first face of the immediately prior sheet has been fully fed passed the target position.

6. A method for feeding sheets, comprising: feeding a first sheet to a first location for flipping sheets with respect to a target position before the first sheet is fed passed the target position; flipping the first sheet and feeding a second face of the first sheet passed the target position; feeding the first sheet to a second location for flipping sheets with respect to the target position, the second location being different than the first location; flipping the first sheet and feeding a first face of the first sheet passed the target position; and feeding a second sheet to the first location for flipping sheets before the first face of the first sheet completes its pass passed the target position.

7. The method of claim 6, wherein the acts of feeding and flipping are performed following receipt of instructions for a duplex operation, the method further comprising, following receipt of instructions for a simplex operation, feeding the first face of the first sheet passed the target position without flipping the first sheet.

8. The method of claim 6, further comprising outputting the first sheet after the first face of the first sheet is fed passed the target position.

9. The method of claim 6, further comprising: after feeding the first face of the first sheet passed the target position, feeding the second face of the second sheet passed the target position; feeding the second sheet to the second location for flipping sheets with respect to the target position; and feeding a first face of the second sheet passed the target position.

10. The method of claim 6, comprising: sequentially feeding each of a plurality of subsequent sheets to the first location for flipping sheets; for each of the subsequent sheets, feeding a second face of that subsequent sheet passed the target position, feeding the subsequent sheet to a second location for flipping the first sheet with respect to the target position, and feeding a first face of the subsequent sheet passed the target position; wherein each subsequent sheet: is fed to the first location for flipping sheets before the first face of an immediately prior sheet is fully fed passed the target position; and the second face of that subsequent sheet is fed passed the target position after the first face of the immediately prior sheet has been fully fed passed the target position.

11. A system for feeding sheets, comprising a first feeder and a second feeder, wherein: the first feeder is operable to feed a sheet to a first location for flipping sheets with respect to a target position before the sheet is fed passed the target position and to feed the sheet to the second feeder; and the second feeder is operable to feed a second face of the sheet passed the target position, to feed the sheet to a second position for flipping sheets with respect to the target position, and to feed a first face of the media sheet passed the target position.

12. The system of claim 11, wherein the first feeder includes an input feeder and a pre-target feeder, the input feeder being operable to feed the sheet to the pre-target feeder along a first path segment and the pre-target feeder being operable to feed the sheet to the first location for flipping sheets and to feed the sheet.

13. The system of claim 12, wherein the sheet has a first edge and a second edge, and wherein the input feeder is operable to feed the sheet with the first edge as a leading edge along the first path segment, and wherein the pre-target feeder is operable to feed the sheet with the second edge as the leading edge along a second path segment to the second feeder.

14. The system of claim 11, wherein the second feeder includes a target feeder and a post-target feeder, the target feeder being operable to feed the sheet passed the target position on to the post-target feeder along a third path segment and wherein the post-target feeder is operable to feed the sheet back to the target feeder along a fourth path segment, the fourth path segment merging with the third path segment.

15. The system of claim 14, wherein the sheet has a first edge and a second edge and wherein the target feeder is operable to feed the sheet with the second edge as a leading edge along the third path segment, wherein the post-target feeder is operable to feed the sheet into a second location for flipping sheets with respect to the target position and to feed the sheet with the first edge leading the sheet along the fourth path segment.

16. The system of claim 11, further comprising a first feeder driver, a second feeder, and a controller and wherein the first feeder includes an input feeder and a pre-target feeder, the second feeder includes a target feeder and a post-target feeder, and the sheet has a first edge and a second edge, wherein: the first feeder driver is operable to drive the input feeder and the pre-target feeder; the second feeder driver is operable to drive the target feeder and the post-target feeder; and the controller is operable to instruct: the first feeder driver to cause the input feeder and the pre-target feeder to feed the sheet with the first edge leading along a first path segment to the first location for flipping sheets; the first feeder driver to cause the pre-target feeder to feed the sheet to the target feeder with the second edge leading along a second path segment to the target feeder; the second feeder driver to cause the target feeder and the post-target feeder to feed the sheet passed the target position with the second edge leading along a third path segment to a second location for flipping sheets; the second feeder driver to cause the post-target feeder to feed the sheet with the first edge leading along a fourth path segment back to the target feeder, the fourth path segment merging with the third path segment; and the second feeder driver to cause the target feeder to feed the sheet passed the target position with the first edge leading along the third path segment.

17. A document feeder, comprising an input feeder, a pre-target feeder, a target feeder, a post target feeder, a first location for flipping sheets and a second location for flipping sheets, wherein: a first path segment extends from the input feeder to the target feeder and on to the post-target feeder and the second position for flipping media sheets; a second path segment extends from the input feeder to the pre-target feeder and on to the first location for flipping media sheets; a third path segment extends from the pre-target feeder merging with the first path segment; and a fourth path segment extending from the post-target position and merging with the first path segment.

18. The document feeder of claims 17, further comprising an input gate moveable between a first position and a second position, wherein: when the input gate is moved to the first position, the input feeder is operable to feed a media sheet along the first path segment; and when the input gate is moved to the second position, the input feeder is operable to feed the sheet along the second path segment.

19. The document feeder of claim 17, wherein: the pre-target feeder is operable to feed a sheet with a first edge leading along the second path segment to the first position for flipping sheets and to feed the sheet with a second edge leading along the third path segment; and the post target feeder is operable to operable to feed the sheet with the second edge leading along the first path segment to the second position for flipping sheets and to feed the sheet with the first edge leading along the fourth path segment.

20. The document feeder of claim 17, further comprising a controller and feeder drivers operable to drive the input feeder, the pre-target feeder, the target feeder and the post-target feeder, wherein the controller is operable to instruct the feeder drivers to cause: the input feeder and the pre-target feeder to feed a first sheet with the a edge leading along the second path segment to the first location for flipping sheets the pre-target feeder to feed the first sheet to the target feeder with a second edge leading along the third path segment and into the first path segment; the target feeder and the post-target feeder to feed the first sheet with the second edge leading along the first path segment to the second location for flipping sheets the post-target feeder to feed the first sheet with the first edge leading along the fourth path segment back into the first path segment; the target feeder to feed the first sheet passed with the first edge leading along the first path segment; and the first feeder to cause the input feeder and the pre-target-feeder to feed a second sheet to the first position for flipping media sheets before the target feeder feeds the first sheet with its first edge leading along the first path segment.

Description:

BACKGROUND

Many imaging devices such as printers, copiers, and scanners have document feeders with duplexing capabilities. These document feeders allow a stack of original to be placed face up in an input tray. The top sheet is pulled from the stack of originals. Each face of that sheet is fed passed a scanner. The sheet is then placed into an output bin. The process repeats until the input tray is emptied. To maintain proper sheet order in the output bin, each sheet is fed passed the scanner three times. The two faces of the sheet are scanned on the first two passes with the sheet being flipped between passes. The third pass is used to flip the sheet to achieve correct order output. This third pass, however, ties up the scanner and limits the speed at which the stack of originals can be fed through the document feeder.

DRAWINGS

FIG. 1 is an exemplary view of an imaging device with a document feeder in which various embodiments may be implemented.

FIG. 2 is an exemplary partial cross sectional view of a document feeder according to an embodiment

FIG. 3 is an exemplary schematic view of a control system for a document feeder according to an embodiment.

FIGS. 4 and 5 are exemplary partial cross sectional views of a document feeder engaging in a simplex operation according to an embodiment.

FIGS. 6-13 are exemplary partial cross sectional views of a document feeder engaged in s a duplex operation according to an embodiment.

FIGS. 14 and 15 are exemplary flow diagrams illustrating steps taken to implement embodiments.

DETAILED DESCRIPTION

INTRODUCTION: FIG. 1 is an exemplary view of a multi-function printer 5. Multi function printer 5is shown to include document feeder 10. Document feeder 10 represents a device capable of sequentially feeding each sheet of a stack of originals placed on input tray 12 to a desired location without assistance from a user. In the Example of FIG. 1, document feeder 10 feeds sheets passed a scanner (not shown) and into output bin 14. Multi-function printer 5 is also shown to include user interface 16 through which the user can guide the operation of document feeder 10. User interface 16, for example, may have a button or other control allowing the user to select a duplex operation in which document feeder 10 causes each face of each sheet to be scanned or a simplex operation in which document feeder 10 causes only one face of each sheet to be scanned.

Various embodiments of the present invention operate to improve the throughput of a document feeder such as document feeder 10 when engaged in a duplex operation. To achieve this goal each sheet is pre flipped and then fed passed a scanner only twice with a different face of sheet being scanned on each pass. In this manner the scanner is utilized on each pass.

COMPONENTS: FIG. 2 is an exemplary partial cross-sectional view of document feeder 10. In this example, a stack 24 of sheets is placed on input tray 12. A sheet is any item such as a sheet of paper that can be fed through document feeder. A sheet such as a sheet of paper has two opposing faces bounded by edges. When a sheet is in motion, it has a leading edge and a trailing edge. When the sheet's motion is reversed, the training edge becomes the leading edge. Each face may or may not include printed matter such as text and images.

In FIG. 2, document feeder is shown to include input feeder 26, pre-target feeder 28, target feeder 30, and post target feeder 32. Feeders 26, 28, 30, and 32 each represent generally any mechanism capable of feeding sheets along a media path. In the Example of FIG. 2, feeders are illustrated to include opposing transport rollers that can be rotated to grip and feed a sheet in a desired direction.

Document feeder 10 also includes a media path having various path segments S1, S2, S3, and S4. Also shown are input gate 34, pre-target gate 36, and post target gate 38. A path segment is a path along which a sheet from stack 24 can be fed by one or more of feeders 26, 28, 30, and 32. Path segment Si extends from input feeder 26 to target feeder and on to post-target feeder. Path segment S2 extends from input feeder 26 through pre-target feeder 28. Path segment S3 extends from pre-target feeder 28 to target feeder 30 merging with path segment S1. Path segment S4 extends from post-target feeder 32 back to target feeder 30 also merging with path segment S1.

Gates 34, 36, and 38 are each moveable between a first position and a second position. The particular path segments S1, S2, S3, and S4 a sheet travels along between input tray 12 and output bin 14 depends in part on the positioning of gates 34, 36, and 38. In the Example of FIG. 2, input feeder 26 when rotated pulls sheet from a top of stack 24. The positioning of input gate 34 determines whether input feeder 26 feeds the sheet along path segment S1 toward target feeder 30 for a simplex operation or if input feeder 26 feeds the sheet along path segment S2 to pre-target feeder 28 for a duplex operation. Input gate 34 may be actively positioned based on whether document feeder 10 is involved in a simplex or duplex operation. Input gate 34 may be positioned, for example by a solenoid or a mechanical switching lever.

The positioning of pre-target gate 36 allows input feeder 26 to feed a sheet to pre-target feeder 28 along path segment S2 until the sheet is fed passed pre-target gate 36. Pre-target gate 36 can then be repositioned so that pre-target feeder 28 can then feed the sheet along path segment S3 to target feeder 30. The positioning of post-target gate 38 allows target feeder 30 to feed a sheet to post-target feeder 32 along path segment Si until the sheet is fed passed post-target gate 38. Post-target gate 38 can then be repositioned so that post-target feeder 32 can then feed sheet back to target feeder 30 along path segment S4.

Pre-target gate 36 and post-target gate 38 may be actively positioned by a mechanical switching lever or solenoid as discussed above with respect to input gate 34. Alternatively, gates 36 and 38 may be passively position. For example, pre-target gate 36 may be held in a default closed position in which a sheet can be fed by pre-target feeder 28 along path segment S3 to target feeder 30. The leading edge of a sheet being fed along path segment S2 opens the pre-target gate 36 as it pushes through at the urging of input feeder 26. Pre-target gate 36 automatically closes after the trailing edge of the sheet has cleared pre-target gate 36. Similarly, post-target gate may be held in a default closed position in which a sheet can be fed by post-target feeder 32 along path segment S4 back to target feeder 30. The leading edge of a sheet being fed along path segment S1 opens the post-target gate 38 as it pushes through at the urging of target feeder 30 allowing the sheet to reach post-target feeder 32. Post-target gate 38 automatically closes after the trailing edge of the sheet has cleared post-target gate 38. Is such a passive implementation, pre-target gate 36 and post-target gate 38 could be flaps of flexible material such as polyester films.

FIG. 2 also shows scanner 40 positioned adjacent to path segment S1. Scanner 40 may or may not be part of document feeder 40. Regardless, scanner 40 is shown to include a light source 42 and a reading element 44. Light source 42 represents generally any source of light that can illuminate a face of a sheet such that the light reflected off of the sheet can be collected by reading element 44. Reading element 44, for example may be a CCD (Charge Coupled Device) array.

Scanner 40 is shown situated at target position 46. Target position 46 represents a position along path segment S1 at which an action can take place with respect to a face of a sheet. In the example of FIG. 2, such an action involves scanning the face of the sheet. Another action example could include printing on or otherwise altering a face of a sheet.

FIG. 3 is an exemplary schematic view of a control system for document feeder 10 of FIGS. 1 and 2. In the Example of FIG. 3, document feeder 10 includes first feeder driver 48 and second feeder driver 50, input gate actuator 52, pre-target gate actuator, post target gate actuator 56, and controller 58. First feeder driver 48 represents components configured to drive input feeder 26 and pre-target feeder 28 causing feeders 26 and 28 to feed a sheet. With reference back to FIG. 2, first feeder driver 48 may be a DC or stepper motor capable of causing input feeder 26 and pre-target feeder 28 to rotate together in one direction. Input feeder 26 may be clutched so that when first feeder drive 48 causes pre-target feeder 28 to reverse, input feeder 26 does not rotate. In this manner, first feeder driver 48 can cause input feeder 26 to feed a sheet to pre target feeder 28 along path segment S2. Once the sheet is positioned, first feeder driver 48 can cause pre-target feeder to reverse and feed the sheet along path segment S3. Because input feeder 26 is clutched, it does not reverse and adversely affect stack 24.

Second feeder driver 48 represents components configured to drive target feeder 30 and post-target feeder 32 causing feeders 30 and 32 to feed a sheet. With reference back to FIG. 2, second feeder driver 50 may be a DC or stepper motor capable of causing target feeder 30 and post-target feeder 32 to rotate together in one direction. Target feeder 30 may be clutched so that when second feeder drive 50 causes post-target feeder 32 to reverse, target feeder 26 does not rotate. Alternatively, target feeder 30 may be geared to only feed sheets in one direction along path segment S1. In this manner, second feeder driver 50 can cause target feeder 30 to feed a sheet passed target position 46 to post-target feeder 32 along path segment S1. Once the sheet is positioned, second feeder driver 50 can cause post-target feeder to reverse and feed the sheet along path segment S4 back to the target position 46. Because target feeder 30 is clutched or geared as discussed, it does not reverse and adversely another sheet that may be present in path segment S1.

FIG. 3 also shows input gate actuator 52, pre target gate actuator 54, and post target gate actuator 56 each coupled to a corresponding gate 34, 36, and 38. Each actuator 52, 54, and 56 represents a device such as a solenoid or mechanical lever capable of positioning a corresponding gate 34, 36, and 38. With reference back to FIG. 2, input gate actuator 52 is configured to selectively position input gate 34 so that a sheet being fed by input feeder passes along path segment S1 or S2.

Where pre-target gate 36 and post-target gate 38 are positioned passively, actuators 54 and 56 would not be included. Otherwise, pre-target gate actuator 54 is configured to selectively position pre-target gate 36 so that a sheet being fed along media path S2 can reach pre-target feeder 28. Pre-target gate actuator 54 can also reposition pre-target gate 36 so that pre-target feeder can be reversed to feed a sheet along path segment S3 to target position 46. Post-target gate actuator 56 is configured to selectively position post-target gate 38 so that a sheet being fed by target feeder 30 along media path S1 can reach post-target feeder 32. Post-target gate actuator 56 can also reposition post-target gate 38 so that post-target feeder 32 can be reversed to feed a sheet along path segment S4 back to target position 46.

Controller 58 represents generally any combination of hardware and programming capable of controlling the operation of first and second feeder drivers 48 and 50 and gate actuators 52, 54, and 56 to cause a stack of sheets to be sequentially fed through document feeder 10. Controller 58 can receive instructions from a user via user interface 16. Referring back to FIG. 2, a user may request a simplex operation in which the sheets are sequentially fed from input tray along path segment S1 passed target position 46 and deposited into output bin 14. In this manner only one face of each sheet is fed passed target position 46.

A user may instead request a duplex operation in which sheets are sequentially fed from input tray 12 along path segment S2, inverted and passed along path segment S3 to path segment S1 passed target position 46. The sheets are then inverted again and passed along path segment S4 to path segment S1, back passed target position 46 and then deposited into output bin 14. In this manner, each sheet makes two passes passed target position 46 with a different face facing target position 46 on each pass.

FIGS. 4 and 5 illustrate an exemplary simplex operation. Starting with FIG. 4 and with reference to FIG. 3, a user has requested a simplex operation via user interface 16. In response, controller 58 has instructed input gate actuator 52 to position input gate 34 in a position allowing sheets to be fed from input tray 12 along path segment S1. Controller 58 has also instructed first feeder driver 48 to cause input feeder 26 to feed a sheet 60 from stack 24. The positioning of input gate 34 has caused sheet 60 to pass along path segment S1 to target feeder 30.

Moving to FIG. 5 and still referring back to FIG. 3, controller 58 has instructed post target gate actuator 56 to position post-target gate 38 to allow sheets to be fed along path segment S1 to post target feeder 32. Controller 58 has also instructed second feeder driver 50 to cause target feeder 30 to feed sheet 60 along path segment S1 passed target position 46 on to post-target feeder 32 to be deposited into output bin 14. While not shown, controller 58 could cause each sheet in stack 24 to be feed in the same manner along path segment S1 and into output bin 14.

FIGS. 6-13 illustrate an exemplary duplex operation. Starting with FIG. 6 and with reference to FIG. 3, a user has requested a duplex operation via user interface 16. In response, controller 58 has instructed input gate actuator 52 and pre-target gate actuator 54 to position input gate 34 and pre-target gate 36 in positions allowing sheets to be fed from input tray 12 along path segment S2 to pre-target feeder 28. Controller 58 has also instructed first feeder driver 48 to cause input feeder 26 to feed a sheet 62 from stack 24. The positioning of input gates 34 and 36 allow sheet 62 to travel along path segment S2 to pre-target feeder 28.

Referring now to FIG. 7, controller 58 has instructed first feeder driver 48 to cause pre-target feeder 28 to pull sheet 62 into a location for flipping sheet 62 with respect to target position 46. A location for flipping is a position in which the direction of travel of a sheet can be reversed and its path altered to invert or flip the sheet with respect to a particular location such as target position 46. In this location for flipping, sheet 62 has been pulled passed pre-target gate 36 with edge 64 leading and edge 66 trailing. Sheet 62 can be flipped with respect to target position 46 by reversing its direction of travel so that edge 66 leads sheet 62 along path segment S3.

Moving to FIG. 8, controller 58 has instructed pre-target gate actuator 54 to position pre-target gate 36 in a position allowing sheets to be fed from pre-target feeder 28 along path segment S3 into path segment S1 and on to target feeder 30. Controller 58 has instructed first feeder driver 48 to cause pre-target feeder 28 to reverse the feed of sheet 62, so that edge 66 leads sheet 62 along path segment S3 on to target feeder 30. Note that input feeder is clutched so that it remains stationary. Controller 58 has also instructed second feeder driver 50 to cause target feeder 30 to feed sheet 62 passed target position 46.

Referring now to FIG. 9, controller 58 has instructed post target gate actuator 56 to position post-target gate 38 to allow sheets to be fed along path segment S1 to post target feeder 32. Controller 58 has also instructed second feeder driver 50 to cause target feeder 30 to feed sheet 62 along path segment S1 passed target position 46 on to post-target feeder 32. In this example, as sheet 62 makes its first pass passed target position 46, controller 58 instructs scanner 40 to scan one face of sheet 62.

Moving to FIG. 10, controller 58 has instructed second feeder driver 50 to cause post-target feeder 32 to pull sheet 62 into a location for flipping sheet 62 with respect to target position 46. In this second location for flipping, sheet 62 has been pulled passed post-target gate 38 with edge 66 leading and edge 64 trailing. Sheet 62 can be once again flipped with respect to target position 46 by reversing its direction of travel so that edge 64 leads sheet 62 along path segment S4.

Referring now to FIG. 11, controller 58 has instructed post target gate actuator 56 to position post-target gate 38 to allow sheets to be fed along path segment S4 back into path segment S1 and on to target feeder 30. Controller 58 has instructed second feeder driver 50 to cause post-target feeder 32 to reverse the feed of sheet 62, so that edge 64 leads sheet 62 along path segment S4 back into path segment S1 and on to target feeder 30. Note that target feeder 30 is geared so that it continues to feed in one direction along path segment S1.

Note also, that controller 58 has instructed input gate actuator 52 and pre-target gate actuator 54 to position input gate 34 and pre-target gate 36 in positions allowing sheets to be fed from input tray 12 along path segment S2 to pre-target feeder 28. Controller 58 has also instructed first feeder driver 48 to cause input feeder 26 to feed a subsequent sheet 68 from stack 24. The positioning of input gates 34 and 36 allow sheet 62 to travel along path segment S2 to pre-target feeder 28. In this manner, sheet 68 can be pulled by pre-target feeder 28 into the location for flipping sheets while the immediately prior sheet 62 is still being fed through document feeder 10. In other words, subsequent sheet 68 can be fed into the first location for flipping sheets before sheet 62 completes its second pass passed target position 46

In FIG. 12, controller 58 has instructed post target gate actuator 56 to position post-target gate 38 to allow sheets to be fed along path segment S1 to post target feeder 32. Controller 58 has also instructed second feeder driver 50 to cause target feeder 30 to feed sheet 62 along path segment S1 passed target position 46 on to post-target feeder 32. In this example, as sheet 62 makes its second pass passed target position 46, controller 58 instructs scanner 40 to scan a second face of sheet 62. Controller 58 can then instruct second feeder driver 50 to cause post-target feeder 32 to deposit sheet 62 into output bin 14.

Note also that controller 58 has instructed first feeder driver 48 to cause pre-target feeder 28 to pull sheet 68 into the first location for flipping sheet 68 with respect to target position 46. Controller 58 has also instructed pre-target gate actuator 54 to position pre-target gate 36 so that pre-target feeder 28 can feed sheet 68 along path segment S3. In this location for flipping, sheet 68 has been pulled passed pre-target gate 36 with edge 70 leading and edge 72 trailing. Sheet 68 can be flipped by reversing its direction of travel so that edge 72 leads sheet 68 along path segment S3.

Moving on to FIG. 13, Controller 58 has instructed second feeder driver 50 to cause post-target feeder 32 to deposit sheet 62 into output bin 14. Meanwhile, controller 58 has instructed first feeder driver 48 to cause pre-target feeder 28 to reverse the feed of sheet 62, so that edge 72 leads sheet 68 along path segment S3 on to target feeder 30. Note that input feeder is clutched so that it remains stationary. Controller 58 has also instructed second feeder driver 50 to cause target feeder 30 to feed sheet 68 on its first pass passed target position 46 after sheet 62 has made its second pass passed target position 46. While not shown, sheet 68 can be flipped again with respect to target position 46 passed along path segment S4 with edge 70 leading back into path segment S1. In this manner, the other face of sheet 68 can be scanned, and sheet 68 can be deposited into output bin 14.

It is noted that while only two sheets 62 and 68 are described as being involved in a duplex operation the operation could involve any number of sheets with each subsequent sheet following the same path segments through document feeder 10. Each subsequent sheet is fed into a first location for flipping the sheet before an immediately prior sheet has completed its second pass passed target position 46. Each subsequent sheet is then fed on its first pass passed target position 46 once an immediately prior sheet has completed its second pass passed target position 46.

It is also noted that FIGS. 6-13 presume that pre-target and post-target gates 36 and 38 are active. As noted above, gates 36 and 38 may be passive in which case the motion of a sheet being fed along path segment S2 would then open pre-target gate 36 allowing the sheet to reach pre-scan feeder 28. Pre-scan gate 36 would automatically close allowing pre-scan feeder 28 to feed the sheet along path segment S3. Similarly, the motion of a sheet being fed along path segment S1 would then open post-target gate 38 allowing the sheet to reach post-scan feeder 32. Post-scan gate 38 would automatically close allowing post-scan feeder 32 to feed the sheet along path segment S4.

OPERATION: FIGS. 14 and 15 are exemplary flow diagrams illustrating steps for implementing various embodiments. Starting with FIG. 14, a sheet is fed to a location for flipping sheets with respect to a target position before the sheet is fed passed that target position (step 74). As described above, a location for flipping is a position in which the direction of travel of a sheet can be reversed so that its leading edge becomes its trailing edge, thus inverting or flipping the sheet with respect to a particular location such as a target position. An example of step 74 is illustrated in FIG. 7.

A second face of the sheet is then fed passed the target position (step 76). Next, the sheet is fed to a second position for flipping media sheets (step 77). A first face of the sheet is then fed passed the target position (step 78). At this point, the sheet has passed the target position only twice with a different face facing the target position on each pass. The sheet can then be output following the second pass. Examples of steps 76 and 78 are illustrated in FIGS. 8-12.

Steps 74-78, for example may be performed following receipt of a user's instruction for a duplex operation. Such an instruction may be entered via user interface 16 shown in FIGS. 1 and 3. Alternatively, a user may instruct a simplex operation. In such a case, a first face of the sheet is fed passed the target position without being fed to the location for flipping sheets.

The duplex operation may involve feeding a plurality of sheets in which case the plurality of sheets are sequentially fed to the location for flipping sheets. The plurality of sheets are sequentially fed so that each subsequent sheet makes a first pass passed the target position and then a second pass passed the target position with a different face facing the target position on each pass. In doing so, each subsequent sheet is fed to the location for flipping sheets before an immediately prior sheet completes its second pass passed the target position. Moreover, that same subsequent sheet is fed to make a first pass passed the target position after the immediately prior sheet has made its second pass passed the target position.

Moving to FIG. 15, a first sheet is fed to a first location for flipping sheets with respect to a target position before the first sheet is fed passed the target position (step 80). The first sheet is flipped and fed passed the target position (step 82). The first sheet is then fed to a second location for flipping sheets with respect to the target position (step 84). Examples of steps 80, 82, and 84 are illustrated in FIGS. 7-10.

A second sheet is fed to the first location for flipping sheets with respect to the target position before the second sheet is fed passed the target position (step 86). Meanwhile, the first sheet is flipped, and a first face of the first sheet is fed passed the target position (step 88). The second sheet is flipped and a second face of the second sheet is fed passed the target position (step 90). An example of steps 86, 88, and 90 is illustrated in FIGS. 11 and 12. It is noted that the second sheet is fed to the first location for flipping sheets in step 86 before the first face of the first sheet completes its pass passed the target position in step 88—that is—before the first sheet makes its second pass passed the target position. The second face of the second sheet is fed passed the target position in step 90 after the first sheet has completed its second pass in step 88.

The second sheet is fed to the second location for flipping sheets with respect to the target position (step 92). The second sheet is flipped and a first face of the second sheet is fed passed the target position (step 94). At this point both faces of the first sheet and the second sheet have been fed passed the target position with each sheet making only two passes passed the target position. After making its second pass passed the target position each or the first and second sheets may be output.

CONCLUSION: The multi-function printer 5 shown in FIG. 1 is an exemplary environment in which embodiments of the present invention may be implemented. Implementation, however, is not limited to this environment. Embodiments can be implemented in any environment in which it is desirable to feed sheets. The diagrams of FIGS. 2-13 show the architecture, functionality, and operation of various embodiments. The block controller 58 in FIG. 3 is defined in part as a program. Controller 58 may represent in whole or in part a module, segment, or portion of code that comprises one or more executable instructions to implement the specified logical function(s). Controller 58 may represent a circuit or a number of interconnected circuits to implement the specified logical function(s).

Also, the present invention can be embodied in any computer-readable media for use by or in connection with an instruction execution system such as a computer/processor based system or an ASIC (Application Specific Integrated Circuit) or other system that can fetch or obtain the logic from computer-readable media and execute the instructions contained therein. “Computer-readable media” can be any media that can contain, store, or maintain programs and data for use by or in connection with the instruction execution system. Computer readable media can comprise any one of many physical media such as, for example, electronic, magnetic, optical, electromagnetic, or semiconductor media. More specific examples of suitable computer-readable media include, but are not limited to, a portable magnetic computer diskette such as floppy diskettes or hard drives, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory, or a portable compact disc.

Although the flow diagrams of FIGS. 14-15 show specific orders of execution, the orders of execution may differ from that which is depicted. For example, the order of execution of two or more blocks may be scrambled relative to the order shown. Also, two or more blocks shown in succession may be executed concurrently or with partial concurrence. All such variations are within the scope of the present invention.

The present invention has been shown and described with reference to the foregoing exemplary embodiments. It is to be understood, however, that other forms, details and embodiments may be made without departing from the spirit and scope of the invention that is defined in the following claims.