Folding device with skew correction

1. A sheet processing apparatus comprising:

a sheet conveyance path extending from an entry portion;

a skew correction roller pair configured to,

contact a leading edge of a sheet conveyed in a first direction from the entry portion, and

correct skew of the sheet when the skew correction roller pair does not rotate;

a receiving path branched from the sheet conveyance path configured to receive the sheet; and

a folding mechanism configured to fold a plurality of overlaid sheets skew-corrected by the skew correction roller pair, the folding mechanism including,

a first conveyer configured to convey the sheet,

a second conveyer downstream from the first conveyer in a sheet conveyance direction, and

a folded portion former configured to form a folded portion on the street,

wherein the second conveyer is configured to form a bent portion in the sheet by conveying the sheet held by the first conveyer and the second conveyer in a second direction opposite to the first direction, and the folded portion former is configured to fold the sheet by receiving the bent portion in the sheet, and

wherein at least one of the first conveyer and the second conveyer serves as the skew correction roller pair.

2. The sheet processing apparatus according to claim 1 , further comprising:

a conveyance roller configured to convey the sheet, wherein the skew correction roller pair is configured to,

convey a preceding sheet to the receiving path in the second direction, and

correct skew of a following sheet conveyed by the conveyance roller, and

wherein the conveyance roller and the skew correction roller pair are configured to,

overlay the following sheet on the preceding sheet conveyed to the receiving path, and

convey the preceding sheet and the following sheet.

3. The sheet processing apparatus according to claim 2 ,

wherein the skew correction roller pair is configured to hold the preceding sheet sandwiched by the skew correction roller pair when skew of the following sheet is corrected.

4. The sheet processing apparatus according to claim 2 ,

wherein the skew correction roller pair is configured to hold the preceding sheet contacting the skew correction roller pair when skew of the following sheet is corrected.

5. The sheet processing apparatus according to claim 1 ,

wherein a sheet conveyance length from the entry portion to the skew correction roller pair is smaller than a maximum size of the sheet.

6. An image forming system comprising:

an image forming apparatus configured to form an image on a sheet, and

the sheet processing apparatus according to claim 1 .

7. The image forming system according to claim 6 ,

wherein the sheet processing apparatus is in an internal ejection section of the image forming apparatus configured to eject the sheet on which an image is formed in a space inside the image forming apparatus.

8. The sheet processing apparatus according to claim 1 ,

wherein the skew correction roller pair is configured to convey the skew-corrected sheet in a second direction opposite the first direction, and

the receiving path is configured to receive the sheet conveyed in the second direction.

9. An image forming system comprising:

an image forming apparatus configured to form an image on a sheet;

a sheet processing apparatus in an internal ejection section of the image forming apparatus configured to eject the sheet in a space inside the image forming apparatus, the sheet processing apparatus including:

a sheet conveyance path extending from an entry portion, the entry portion coupled to the image forming apparatus;

a skew correction roller pair configured to,

contact a leading edge of the sheet conveyed in a first direction from the entry portion, and

correct skew of the sheet when the skew correction roller pair does not rotate;

a receiving path branched from the sheet conveyance path between the entry portion and the skew correction roller pair configured to receive the sheet;

a plurality of conveyance rollers configured to convey the sheet; and

circuitry configured to control the plurality of conveyance rollers to convey the sheet into the sheet processing apparatus and the skew correction roller pair to convey the sheet to the receiving path, after the leading edge of the sheet contacts the skew correction roller pair.

10. The image forming system according to claim 9 , further comprising a folding mechanism configured to overlay and fold a plurality of sheets skew-corrected by the skew correction roller pair.

11. The image forming system according to claim 10 ,

wherein the folding mechanism includes:

a first conveyer configured to convey the sheet;

a second conveyer downstream from the first conveyer in a sheet conveyance direction; and

a folded portion former configured to form a folded portion on the sheet,

wherein the circuitry is configured to,

control the second conveyer to form a bent portion in the sheet by conveying the sheet held by the first conveyer and the second conveyer in a second direction opposite to the first direction, and

control the first conveyer, the second conveyer, and the folded portion former to convey the bent portion of the sheet into the folded portion former, and

wherein at least one of the first conveyer and the second conveyer serves as the skew correction roller pair.

12. The image forming system according to claim 9 ,

wherein the circuitry is configured to,

control the skew correction roller pair to convey a preceding sheet to the receiving path,

control the plurality of conveyance rollers and the skew correction roller pair to convey a following sheet and correct skew of the following sheet, and

control the skew correction roller pair to overlay the following sheet on the preceding sheet conveyed to the receiving path.

13. The image forming system according to claim 12 ,

wherein the circuitry is configured to control the skew correction roller pair to hold the preceding sheet sandwiched by the skew correction roller pair when skew of the following sheet is corrected.

14. The image forming system according to claim 12 ,

wherein the circuitry is configured to control the skew correction roller pair to hold the preceding sheet contacting the skew correction roller pair when skew of the following sheet is corrected.

15. The image forming system according to claim 9 ,

wherein a sheet conveyance length from the entry portion to the skew correction roller pair is smaller than a maximum size of the sheet.

16. The image forming system according to claim 9 ,

wherein the skew correction roller pair is configured to convey the skew-corrected sheet in a second direction opposite the first direction,

the receiving path is configured to receive the sheet conveyed in the second direction, and

the circuitry is configured to control the skew correction roller pair to convey the sheet to the receiving path in the second direction.

17. A sheet processing apparatus comprising:

a sheet conveyance path extending from an entry portion;

a skew correction roller pair configured to,

contact a leading edge of a sheet conveyed in a first direction from the entry portion, and

correct skew of the sheet when the skew correction roller pair does not rotate;

a receiving path branched from the sheet conveyance path configured to receive the sheet; and

a conveyance roller configured to convey the sheet,

wherein the skew correction roller pair is configured to,

convey a preceding sheet to the receiving path in a second direction opposite the first direction, and

correct skew of a following sheet conveyed by the conveyance roller, and

wherein the conveyance roller and the skew correction roller pair are configured to,

overlay the following sheet on the preceding sheet conveyed to the receiving path, and

convey the preceding sheet and the following sheet.

18. The sheet processing apparatus according to claim 17 ,

wherein the skew correction roller pair is configured to hold the preceding sheet sandwiched by the skew correction roller pair when skew of the following sheet is corrected.

19. The sheet processing apparatus according to claim 17 ,

wherein the skew correction roller pair is configured to hold the preceding sheet contacting the skew correction roller pair when skew of the following sheet is corrected.

20. The sheet processing apparatus according to claim 17 ,

wherein a sheet conveyance length from the entry portion to the skew correction roller pair is smaller than a maximum size of the sheet.

21. An image forming system comprising:

an image forming apparatus configured to form an image on a sheet, and the sheet processing apparatus according to claim 17 .

22. The image forming system according to claim 21 ,

wherein the sheet processing apparatus is in an internal ejection section of the image forming apparatus configured to eject the sheet on which an image is formed in a space inside the image forming apparatus.