Sheet conveying apparatus and image forming apparatus
A sheet conveying apparatus according to the present invention includes: a pair of conveying rollers 13 which nips and conveys a sheet; a reference member 31 which determines the position of a side edge of the sheet along the sheet conveyance direction; a plurality of pairs of skew feeding correcting rollers 32 which nip and convey the sheet conveyed by the pair of conveying rollers 13 and draw the side edge of the sheet to the reference member 31 ; and a switching unit which switches the pair of conveying rollers 13 and the pairs of skew feeding correcting rollers 32 between a state of nipping the sheet and a state of nip releasing the sheet, the switching unit releasing the nip of the sheet by the pair of conveying rollers 13 after the conveyed sheet is nipped by at least two of the pairs of skew feeding correcting rollers 32.
1. A sheet conveying apparatus comprising:
a pair of rotary portions that nip and convey a sheet in a sheet conveying direction;
a reference surface which is provided along the sheet conveying direction;
a first conveying portion which, obliquely with respect to the sheet conveying direction, conveys the sheet conveyed by the pair of rotary portions so as to contact the side edge of the sheet to the reference surface;
a second conveying portion which is disposed downstream of the first conveying portion in the sheet conveying direction and which, obliquely with respect to the sheet conveying direction, conveys the sheet so as to contact the side edge of the sheet to the reference surface;
a switching portion which switches the pair of rotary portions between a state of nipping the sheet and a state of nip releasing the sheet;
a detecting portion which detects the sheet conveyed by the pair of rotary portions; and
a controller which controls to stop the rotation of the pair of rotary portions based on the detection of the detecting portion before the leading edge of the sheet reaches the second conveying portion, and controls the switching portion so that the nip of the sheet by the pair of rotary portions is released after the pair of rotary portions starts rotating and the leading edge of the sheet in the conveying direction reaches the second conveying portion.
2. The sheet conveying apparatus according to claim 1 , wherein
the detecting portion is disposed downstream of the pair of rotary portions and upstream of the first conveying portion in the sheet conveying direction.
3. The sheet conveying apparatus according to claim 1 , wherein the pair of rotary portions includes a pair of rollers formed of a driving roller and a driven roller, the driving roller being rotated by driving force from a drive source and a driven roller being pressed with the driving roller.
4. The sheet conveying apparatus according to claim 1 , wherein a sheet conveying force of the pair of rotary portions is set to be larger than that of the first conveying portion.
5. The sheet conveying apparatus according to claim 1 , wherein a direction of conveying the sheet by the first conveying portion and the second conveying portion is at a predetermined angle with respect to the reference surface.
6. The sheet conveying apparatus according to claim 1 , wherein the first conveying portion and the second conveying portion obliquely convey the sheet to contact the side edge of the sheet to the reference surface to correct skew feeding of the sheet conveyed by the pair of rotary portions.
7. The sheet conveying apparatus according to claim 1 , wherein the sheet conveying forces of the pair of rotary portions, the first conveying portion, and the second conveying portion are set so as to convey the sheet in the sheet conveying direction in a state that the pair of rotary portions, the first conveying portion, and the second conveying portion nip the same sheet.
8. The sheet conveying apparatus according to claim 1 , wherein
the first conveying portion has a first roller pair which nips the sheet,
the second conveying portion has a second roller pair which nips the sheet, and
the first roller pair receives a leading edge of the sheet conveyed by the pair of the rotary portions in a condition that the rollers of the first roller pair contact each other and the second roller pair receives a leading edge of the sheet conveyed by the pair of the rotary portions in a condition that the rollers of the second roller pair contact each other, and the controller controls the switching portion to release the nip of the sheet by the pair of rotary portions in a state that both the first roller pair and the second roller nip the sheet.
9. A sheet conveying apparatus according to claim 1 , wherein
the first conveying portion has a first roller pair which nips the sheet,
the second conveying portion has a second roller pair which nips the sheet, and
a leading edge of the sheet conveyed by the pair of the rotary portions passes the first roller pair in a condition that the rollers of the first roller pair are apart from each other and a leading edge of the sheet conveyed by the pair of the rotary portions passes the second roller pair in a condition that the rollers of the second roller pair are apart from each other, and the controller controls the switching portion to release the nip of the sheet by the pair of rotary portions in a state that both the first roller pair and the second roller nip the sheet.
10. An image forming apparatus, comprising:
a sheet conveying apparatus including
a pair of rotary portions that nip and convey a sheet in a sheet conveying direction;
a reference surface which is provided along the sheet conveying direction;
a first conveying portion which, obliquely with respect to the sheet conveying direction, conveys the sheet conveyed by the pair of rotary portions so as to contact the side edge of the sheet to the reference surface;
a second conveying portion which is disposed downstream of the first conveying portion in the sheet conveying direction and which, obliquely with respect to the sheet conveying direction, conveys the sheet so as to contact the side edge of the sheet to the reference surface;
a switching portion which switches the pair of rotary portions between a state of nipping the sheet and a state of nip releasing the sheet;
a detecting portion which detects the sheet conveyed by the pair of rotary portions;
a controller which controls to stop the rotation of the pair of rotary portions based on the detection of the detecting portion before the leading edge of the sheet reaches the second conveying portion, and controls the switching portion so that the nip of the sheet by the pair of rotary portions is released after the pair of rotary portions starts rotating and the leading edge of the sheet in the conveying direction reaches the second conveying portion; and
an image forming portion which forms an image on the sheet conveyed by the sheet conveying apparatus.
11. The image forming apparatus according to claim 10 , wherein the sheet conveying forces of the pair of rotary portions, the first conveying portion, and the second conveying portion are set so as to convey the sheet in the sheet conveying direction in a state that the pair of rotary portions, the first conveying portion, and the second conveying portion nip the same sheet.