Printing system sheet feeder

• US 20060290047A1
• Filed: 06/24/2005
• Published: 12/28/2006
• Est. Priority Date: 06/24/2005
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Moore, Steven R.
• Granted Patent: US 7,387,297 B2
• Time in Patent Office: Days
• US Class Current: 271/10.11
• CPC Class Codes: B65H 2301/4231 by two or more separators acting selectively on the same pile
• CPC Class Codes: B65H 2301/42324 from top of the pile
• CPC Class Codes: B65H 2701/1313 trailing edge
• CPC Class Codes: B65H 3/0676 with two or more separator rollers in the feeding direction
• CPC Class Codes: B65H 3/46 Supplementary devices or measures to assist separation or prevent double feed control means comprising detectors responsive to double feed B65H7/12

Abstract

A printing system sheet feeder apparatus and method is provided. The printing system feeder includes a front nudger roll positioned near the leading edge of the top sheet of a sheet stack and the front nudger roll is capable of advancing the top sheet. In addition, the printing system sheet feeder includes a separation nip aligned with the front nudger roll, the front nudger roll being capable of receiving the top sheet advanced by the front nudger roll and advancing the top sheet in a direction away from the front nudger. A rear nudger roll is positioned near the trailing edge of the top sheet and is capable of advancing the sheet directly below the top sheet while the top sheet is being advanced by the front nudger roll and/or separation nip, thereby increasing the overall sheet feeding rate to the printing system.

Claims

1. A printing system sheet feeder apparatus comprising:

a sheet stack comprising two or more sheets of media stacked in a vertical position which includes a top sheet and a sheet directly below the top sheet, each sheet including a leading edge and a trailing edge;

a front nudger roll positioned near the leading edge of the top sheet of the sheet stack, capable of advancing the top sheet;

a separation nip aligned with the front nudger roll and capable of receiving the top sheet advanced by the front nudger roll and advancing the top sheet in a direction away from the front nudger; and

a rear nudger roll, the rear nudger roll being positioned near the trailing edge of the top sheet and capable of advancing the sheet directly below the top sheet while the top sheet is being advanced by the front nudger roll and/or separation nip.

2. The apparatus of claim 1, further comprising:

a take-away nip aligned with the separator nip and cable of receiving the top sheet advanced by the separation nip, the take-away nip advancing the top sheet to a sheet path independent of the sheet feeder apparatus and the take-away nip capable of advancing the sheet at speeds greater that the speed of the separation nip.

3. The apparatus of claim 2, the take away nip further comprising:

a drive roll; and

an idler roll.

4. The apparatus of claim 1, further comprising:

a sheet stack tray comprising an elevator lift plate to advance the sheet stack in a vertical direction;

a sheet stack trail edge guide for controlling the lateral position of the sheet stack in one direction;

a sheet stack lead edge guide for controlling the lateral position of the sheet stack in another direction; and

a sheet stack height sensor.

5. The apparatus of claim 4, wherein the rear nudger roll is adjustably mounted to the sheet stack trailing edge guide.

6. The apparatus of claim 4, wherein the rear nudger roll is fixed to the sheet stack trailing edge guide.

7. The apparatus of claim 1, further comprising:

a belt drive mechanism integrated with the front nudger roll and the separation nip, wherein the front nudger roll and the separation nip rotate in a direction that advances the top sheet in a direction oriented from the front nudger roll to the separation nip.

8. The apparatus of claim 1, the separation nip further comprising:

a mechanically driven feed roll; and

a retard roll, the feed roll and the retard roll aligned to advance one sheet advanced from the front nudger.

9. The apparatus of claim 1, the rear nudger roll further comprising:

a mechanically driven roll.

10. The apparatus of claim 1, the rear nudger roll further comprising:

a D-roll segment to advance the top sheet.

11. The apparatus of claim 1, wherein the rear nudger roll axis of rotation is located a distance X1 from the trailing edge of the sheet stack, and the separation nip axis of rotation is located a distance X2 from the leading edge of the sheet stack, and the front nudger roll engages and advances the top sheet in a direction towards the separation nip.

12. The apparatus of claim 11, wherein the distance X1 is less than distance X2.

13. The apparatus of claim 12, wherein the distance X1 is approximately equal to distance X2.

14. The apparatus of claim 11, wherein the rear nudger roll engages and advances the sheet directly below the top sheet in a direction towards the separation nip and for a distance X1.

15. The apparatus of claim 14, further comprising:

a sheet acquisition sensor aligned with the separation nip to detect the leading edge of a sheet advancing from the separation nip.

16. The apparatus of claim 1, further comprising:

a nearly zero-rated spring, wherein the rear nudger roll is vertically suspended above the sheet stack by the spring and the rear nudger roll engages the sheet directly below the top sheet.

17. A method of feeding sheets to a printing system comprising:

starting a sheet feed cycle;

applying a tangential force near the leading edge of a top sheet of a sheet stack;

driving the top sheet into a separation nip;

removing the said force near the leading edge of the top sheet after the top sheet leading edge passes through the separation nip;

driving the top sheet with the separation nip to a take-away nip, while simultaneously applying a tangential force near the trailing edge of a next sheet directly below the top sheet; and

removing the tangential force from the next sheet after driving the next sheet a predetermined distance towards the separation nip.

18. A xerographic printing system comprising:

one or more sheet feeder apparatuses, each sheet feeder apparatus comprising;

a sheet stack comprising two or more sheets of media stacked in a vertical position which includes a top sheet and a sheet directly below the top sheet, each sheet including a leading edge and a trailing edge;

a front nudger roll positioned near the leading edge of the top sheet of the sheet stack, capable of advancing the top sheet;

a separation nip aligned with the front nudger roll and capable of receiving the top sheet advanced by the front nudger roll and advancing the top sheet in a direction away from the front nudger; and

a rear nudger roll, the rear nudger roll being positioned near the trailing edge of the top sheet and capable of advancing the sheet directly below the top sheet while the top sheet is being advanced by the front nudger roll and/or separation nip.

19. A xerographic printing system according to claim 18, further comprising:

a sheet stack comprising two or more sheets of media stacked in a vertical position which includes a top sheet and a sheet directly below the top sheet, each sheet including a leading edge and a trailing edge;

a front nudger roll positioned near the leading edge of the top sheet of the sheet stack, capable of advancing the top sheet;

a separation nip aligned with the front nudger roll and capable of receiving the top sheet advanced by the front nudger roll and advancing the top sheet in a direction away from the front nudger;

a rear nudger roll, the rear nudger roll being positioned near the trailing edge of the top sheet and capable of advancing the sheet directly below the top sheet while the top sheet is being advanced by the front nudger roll and/or separation nip; and

a take-away nip aligned with the separator nip and cable of receiving the top sheet advanced by the separation nip, the take-away nip advancing the top sheet to a sheet path independent of the sheet feeder apparatus and the take-away nip capable of advancing the sheet at speeds greater than the speed of the separation nip.

20. A xerographic printing system according to claim 19, further comprising:

one or more printing modules

one or more feed modules; and

one or more finishing modules.