Sheet Discharge Roller Assembly For An Automatic Document Feeding Apparatus
A sheet discharge roller assembly for a sheet feeding apparatus includes an upper cylindrical exit roller mounted on a rotatable drive shaft and a lower cylindrical pinch roller having a wheel attached to one end. The pinch roller has a length that is longer than the length of the exit roller and is moveable into contact with the exit roller so as to form a nip for gripping a print media to be discharged. The wheel has a diameter that is larger than that of the pinch roller and an outer circumferential edge composed of a plurality of protruding contact portions arranged in a radial pattern. The wheel is positioned so that the wheel can contact the media sheet being gripped and cause the sheet to deform temporarily, thereby making the sheet more rigid.
The present invention generally relates to sheet discharge systems, particularly sheet discharge systems for automatic document feeding apparatuses.
BACKGROUNDMany multifunction printers, copying machines and stand-alone scanners are provided with an automatic document feeder (ADF) for automatically transporting individual sheets from a stack of media sheets to an image reading region, and then ejecting and restacking the sheets automatically onto an output tray. It is desirable to neatly restack the media sheets as the sheets exit the ADF. However, this may be difficult to achieve. The incoming ejected sheet tends to slide across the previously ejected sheet. The friction between the sheets may lead to incomplete ejection or skewing of the sheets relative to each other. Known solutions for this problem include modifying the geometry of the output tray to achieve proper stacking, such as inclining the output tray at a steep angle or placing several edge guides on the output tray. These known solutions either produce an unattractive output design or add cost to the ADF. There remains a need for improving the stacking of ejected sheets in ADF devices without adding special features to the output tray or modifying the geometry of the output tray.
SUMMARYThe present invention provides a sheet discharge roller assembly that can improve stacking of media sheets at the output area of an automatic document feeder without adding special features to the output area. In one embodiment, the sheet discharge roller assembly includes an upper cylindrical exit roller mounted on a rotatable drive shaft and a lower cylindrical pinch roller having a wheel attached to one end. The pinch roller has a length that is longer than the length of the exit roller and is moveable into contact with the exit roller so as to form a nip for gripping a print media to be discharged. The wheel has a diameter that is larger than that of the pinch roller and an outer circumferential edge composed of a plurality of protruding contact portions arranged in a radial pattern. The wheel is positioned so that the wheel can contact the media sheet being gripped and cause the sheet to deform temporarily, thereby making the sheet more rigid.
The objects and advantages of the present invention will become apparent from the detailed description when read in conjunction with the drawings.
Referring to
During the process of discharging a media sheet to the output tray, the pinch rollers 22 are biased against the corresponding exit rollers 21 so as to define a nip that grips the media sheet being discharged, and the pinch rollers 22 rotate in synchronism with the rotation of the exit rollers 21 to move the media sheet toward the output tray. The wheels 22a attached to pinch rollers 22 cause the nipped media sheet to be deformed temporarily, thereby making the sheet more rigid. This deformation results in less droop and drag of the media sheet as the sheet exits the ADF, thereby resulting in a more orderly media stacking. Furthermore, the scalloped edge design gently pushes the trailing edge of the exiting media sheet past the exit rollers 21, thereby preventing incomplete ejection and clinging of the media sheet at the output area of the ADF.
While particular embodiments of the present invention have been described, it will be understood by those skilled in the art that modifications and substitutions can be made without departing from the scope of the invention as set forth in the following claims.
Claims
1. A sheet discharge roller assembly comprising:
- an upper cylindrical exit roller mounted on a rotatable drive shaft; and
- a lower cylindrical pinch roller having a wheel attached to only one end so as to rotate synchronously with said pinch roller, said wheel having a diameter that is larger than that of the pinch roller and an outer circumferential edge composed of a plurality of protruding contact portions arranged in a radial pattern,
- wherein said pinch roller has a length that is longer than the length of the exit roller and is moveable into contact with said exit roller so as to form a nip for gripping a print media to be discharged, and
- said wheel is positioned so that said wheel can contact the media sheet being gripped and cause the sheet to deform temporarily, thereby making the sheet more rigid.
2. The sheet discharge roller assembly of claim 1, wherein the outer circumferential edge of the wheel has a scalloped edge configuration.
3. The sheet discharge roller assembly of claim 1, wherein the outer circumferential edge of the wheel has a serrated edge configuration.
4. The sheet discharge roller assembly of claim 1, wherein the pinch roller is rotatably mounted to a housing, and is maintained in a spring-biased position by a U-shaped wire spring such that the pinch roller can be spring biased against the exit roller to define a nip therebetween.
5. A sheet discharge roller assembly comprising:
- two upper cylindrical exit rollers mounted on a rotatable drive shaft; and
- two lower cylindrical pinch rollers opposing said exit rollers, each pinch roller having a wheel attached to only one end so as to rotate synchronously with said pinch roller, said wheel having a diameter that is larger than that of the pinch roller and an outer circumferential edge composed of a plurality of protruding contact portions arranged in a radial pattern,
- wherein each pinch roller is moveable into contact with a corresponding exit roller so as to form a nip for gripping a print media to be discharged, each pinch roller has a length that is greater than the length of the corresponding exit roller, and the pinch rollers are arranged so that the ends without the wheels are facing each other and the distance between the wheels is greater than the combined lengths of the exit rollers plus the distance between the exit rollers, whereby the wheels can contact the media sheet being gripped near the side edges of the sheet and cause the sheet to deform temporarily, thereby making the sheet more rigid.
6. The sheet discharge roller assembly of claim 5, wherein the outer circumferential edge of the wheel has a scalloped edge configuration.
7. The sheet discharge roller assembly of claim 5, wherein the outer circumferential edge of the wheel has a serrated edge configuration.
8. The sheet discharge roller assembly of claim 5, wherein each pinch roller is rotatably mounted to a housing, and is maintained in a spring-biased position by a U-shaped wire spring such that the pinch roller can be spring biased against the corresponding exit roller to define a nip there between.
9. An automatic document feeder comprising:
- an input tray for supporting a stack of media sheets;
- an output tray;
- a main media path for guiding a media sheet from the input tray to a scanning region and from the scanning region to the output tray;
- a pickup unit for picking a sheet, one by one, from the stack of media sheets in the input tray and feeding the sheet into the main media path; and
- a sheet discharge roller assembly configured to discharge the sheet onto the output tray, said sheet discharge roller assembly comprising: (a) at least one upper cylindrical exit roller mounted on a rotatable drive shaft; and (b) at least one lower cylindrical pinch roller having a wheel attached to only one end so as to rotate synchronously with said pinch roller, said wheel having a diameter that is larger than that of the pinch roller and an outer circumferential edge composed of a plurality of protruding contact portions arranged in a radial pattern, wherein said pinch roller has a length that is longer than the length of the exit roller and is moveable into contact with said exit roller so as to form a nip for gripping a print media to be discharged, and said wheel is positioned so that said wheel can contact the media sheet being gripped and cause the sheet to temporarily deform, thereby making the sheet more rigid.
10. The automatic document feeder of claim 9, wherein there are two spaced-apart upper cylindrical exit rollers mounted on the drive shaft and there are two lower cylindrical pinch rollers in opposing relationship to the exit rollers, each pinch roller being moveable into contact with a corresponding exit roller so as to form a nip, and
- wherein the pinch rollers are arranged so that the ends without the wheels are facing each other, and the distance between the wheels is greater than the combined lengths of the exit rollers plus the distance between the exit rollers, whereby the wheels can contact the media sheet being gripped near the side edges of the sheet and cause the sheet to deform temporarily, thereby making the sheet more rigid.
11. The automatic document feeder of claim 10, wherein each pinch roller is rotatably mounted to a housing, and is maintained in a spring-biased position by a U-shaped wire spring such that the pinch roller can be spring biased against the corresponding exit roller to define a nip there between.
Type: Application
Filed: Apr 26, 2007
Publication Date: Oct 30, 2008
Inventors: Toh Tung Wong (Singapore), Keng Leong NG (Singapore), Wayne E. Foote (Eagle, ID), Jeffrey C. Madsen (Eagle, ID), Thaddie Natalaray (Singapore), Kyi Thu Maung (Singapore)
Application Number: 11/740,293
International Classification: B65H 29/20 (20060101); B65H 5/00 (20060101);