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БИБЛИОТЕКА ПАТЕНТОВ НА ИЗОБРЕТЕНИЯ

Image forming apparatus and method of feeding a sheet


Классы МПК:B65H5/06 с помощью роликов 
Автор(ы): Akiyama, Shigeki (Ichinomiya, JP)
Hirano, Masatoshi (Nagoya, JP)
Патентообладатель(и): Brother Kogyo Kabushiki Kaisha (Nagoya-shi, Aichi-ken, JP)
Приоритеты:
подача заявки
02.06.2008
публикация патента
11.10.2011

РЕФЕРАТ (Abstract)

An image forming apparatus includes a tray, a sheet conveying path through which sheets are conveyed, a sheet feeding unit including a sheet feed roller for feeding a first sheet to a sheet holding position, a sheet conveying unit having a conveyor roller that intermittently rotates and holds the sheets. The sheet conveying unit is upstream from a recording position, and downstream from the sheet feeding unit. The image forming apparatus also includes a recording unit, and a controller. The recording unit forms an image onto the first sheet while the conveyor roller is not rotating. The sheet feeding unit feeds a leading edge of a second sheet to the sheet conveying unit and maintains the leading edge of the second sheet colliding against the sheet conveying unit at the sheet holding position by rotating the sheet feed roller prior to completing image formation on the first sheet.
Полный текст Патента US 8033541 + PDF


ФОРМУЛА ИЗОБРЕТЕНИЯ (CLAIMS)

What is claimed is:

1. An image forming apparatus comprising: a tray configured to accommodate a plurality of sheets; a sheet conveying path through which the plurality of sheets are conveyed; a sheet feeding unit comprising a sheet feed roller configured to feed the plurality of sheets one by one from the tray through the sheet conveying path to a sheet holding position, and a sheet feed motor configured to rotate to transfer a drive force to the sheet feed roller; a sheet conveying unit comprising: a conveyor roller configured to intermittently hold a first sheet at the sheet holding position and to transport the first sheet intermittently; and a conveyor motor configured to, independently from the sheet feed motor, rotate to transfer a drive force to the conveyor roller, the conveyor roller being disposed upstream from a recording position and downstream from the sheet feed roller with respect to a sheet feed direction, the sheet holding position being positioned upstream from the recording position and downstream from the sheet feed roller with respect to the sheet feed direction; a recording unit configured to form an image onto a surface of the first sheet stopped at the recording position; and a controller configured to control the sheet feed motor and the conveyor motor such that the conveyor roller does not rotate while the recording unit forms an image onto the first sheet, such that the sheet feed roller continues to rotate to feed a second sheet from the tray through the sheet conveying path to a predetermined position which is positioned upstream of the sheet holding position both when the conveyor roller is rotating to transport the first sheet and when the conveyor roller is not rotating while the recording unit forms an image onto the first sheet, and when the second sheet reaches the predetermined position, the sheet feed roller stops rotating, and such that when the conveyor roller stops rotating while the recording unit forms an image onto the first sheet, the sheet feed roller restarts rotating and keeps rotating to maintain colliding of a leading edge of the second sheet against the conveyor roller, which is not rotating at the sheet holding position, to correct a skew of the second sheet.

2. The image forming apparatus of claim 1, further comprising a sheet discharging unit comprising a discharge roller configured to rotate intermittently in synchronization with the conveyor roller, and disposed downstream from the recording position.

3. The image forming apparatus of claim 2, wherein the sheet discharging unit is configured to hold the first sheet while the recording unit forms an image, and to discharge the sheet to a downstream end of the sheet conveying path by the rotation of the discharge roller.

4. The image forming apparatus according to claim 1, wherein the controller is configured to determine whether a trailing edge of the first sheet, which is conveyed downstream in the sheet conveying path by the conveyor roller, has passed the sheet holding position, and wherein when the trailing edge of the first sheet has passed the sheet holding position, the sheet feeding unit is configured to feed the second sheet from the tray to the sheet holding position, until the second sheet contacts the conveyor roller at the sheet holding position.

5. The image forming apparatus according to claim 1, wherein the sheet feeding unit is configured to feed the second sheet from the tray a predetermined distance which temporarily positions a leading edge of the second sheet at a predetermined standby position upstream from the sheet holding position in the sheet conveying path, and wherein the sheet feeding unit is configured to feed the second sheet to the conveyor roller at a position in which the second sheet contacts the conveyor roller at the sheet holding position, to correct a skew of the second sheet while the conveyor roller is not rotating.

6. The image forming apparatus according to claim 5, wherein the controller is configured to determine whether a trailing edge of the first sheet, which is fed to the conveyor roller, has passed the standby position, and when the trailing edge of the first sheet passes the standby position, the sheet feeding unit is configured to begin feeding the second sheet from the tray.

7. The image forming apparatus according to claim 5, wherein the sheet feeding unit is configured to further convey the second sheet, which is temporarily positioned at the standby position, to the sheet holding position after the conveyor roller and the discharge roller stop rotating.

8. The image forming apparatus according to claim 1, wherein the controller is configured to determine whether to feed the second sheet to the conveyor roller, and the sheet feeding unit is configured to return the second sheet to the tray when the controller determines not to feed the second sheet to the conveyor roller.

9. The image forming apparatus of claim 1, wherein the controller is further configured to control the sheet feed motor and the conveyor motor such that the sheet feed roller rotates without rotating the conveyor roller while the recording unit forms an image onto the first sheet.

10. The image forming apparatus of claim 1, wherein the controller is further configured to control the sheet feed motor and the conveyor motor such that the rotating of the conveyor roller and the forming of an image without rotating the conveyor roller are alternately repeated while the sheet feed roller rotates for feeding the second sheet.

11. A method of feeding a sheet for an image forming apparatus, the image forming apparatus comprising a sheet feeding unit comprising a sheet feed roller and a sheet feed motor configured to rotate to transfer a drive force to the sheet feed roller, a sheet conveying unit comprising a conveyor roller disposed upstream from a recording position and downstream from the sheet feed roller with respect to a sheet feed direction, the sheet holding position being positioned upstream from the recording position and downstream from the sheet feed roller with respect to the sheet feed direction, and a conveyor motor configured to, independently from the sheet feed motor, rotate to transfer a drive force to the conveyor roller, and a recording unit configured to form an image onto a surface of a first sheet at a recording position, the method comprising the steps of (a) controlling the sheet feed motor to feed a plurality of sheets one by one from a tray through a sheet conveying path to a sheet holding position; (b) controlling the conveyor motor to intermittently hold the first sheet at the sheet holding position and transport the first sheet intermittently; and (c) controlling the sheet feed motor and the conveyor motor such that the conveyor roller does not rotate while the recording unit forms an image onto the first sheet, such that the sheet feed roller continues to rotate to feed a second sheet from the tray through the sheet conveying path to a predetermined position which is positioned upstream of the sheet holding position both when the conveyor roller is rotating to transport the first sheet and when the conveyor roller is not rotating while the recording unit forms an image onto the first sheet, and when the second sheet reaches the predetermined position, the sheet feed roller stops rotating and such that when the conveyor roller stops rotating while the recording unit forms an image onto the first sheet, the sheet feed roller restarts rotating and keeps rotating to maintain colliding of a leading edge of the second sheet against the conveyor roller, which is not rotating at the sheet holding position, to correct a skew of the second sheet.

12. The method of feeding a sheet according to claim 11, further comprising the steps of: determining whether a trailing edge of the first sheet, which is conveyed toward the downstream in the sheet conveying path by the controlling step (a), has passed the sheet holding position; and feeding the second sheet from the tray to the sheet holding position when the trailing edge of the first sheet has passed the sheet holding position, until the second sheet contacts a conveyor roller at the sheet holding position.

13. The method of feeding a sheet according to claim 11, further comprising the steps of: feeding the second sheet from the tray a predetermined distance which temporarily positions a leading edge of the second sheet at a predetermined standby position upstream from the sheet holding position in the sheet conveying path; and feeding the second sheet to the conveyor roller at a position in which the second sheet contacts the conveyor roller at the sheet holding position, to correct the skew of the second sheet while the conveyor roller is not rotating.

14. The method of feeding a sheet according to claim 13, further comprising the steps of: determining whether a trailing edge of the first sheet, which is fed to the conveyor roller, has passed the standby position; and beginning to feed the second sheet from the tray when the determining step determines that the trailing edge of the first sheet has passed the standby position.

15. The method of feeding a sheet according to claim 13, further comprising the step of further conveying the second sheet, which is temporarily positioned at the standby position, to the sheet holding position immediately after the conveyor roller and a discharge roller stop rotating.

16. The method of feeding a sheet according to claim 11, further comprising the steps of: determining whether to feed the second sheet to the conveyor roller; and returning the second sheet to the tray when the determining step determines not to feed the second sheet to the conveyor roller.

17. The method of feeding a sheet according to claim 11, wherein the controlling step (c) comprises controlling the sheet feed motor and the conveyor motor such that the sheet feed roller rotates without rotating the conveyor roller while the recording unit forms an image onto the first sheet.

18. The method of feeding a sheet according to claim 11, wherein the controlling step (c) comprises controlling the sheet feed motor and the conveyor motor such that the rotating of the conveyor roller and the forming an image without rotating the conveyor roller are alternately repeated while the sheet feed roller rotates for feeding the second sheet.


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