# US 7,607,660 B2 · Sheet conveying apparatus, image forming apparatus, and image scanning apparatus

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- Number: US 7,607,660 B2
- Document ID: US7607660B2
- Status: Granted
- Kind: B2
- Application number: 11/766,467
- Filed: 2007-06-21
- Published: 2008-01-10
- Granted: 2009-10-27
- Earliest claimed: 2006-06-26
- Assignees: Canon Kabushiki Kaisha
- Inventors: Hiroshige Inoue
- Web page: https://patentgrep.com/patent/US7607660B2

## CPC

- B65H 9/002: {changing orientation of sheet by only controlling movement of the forwarding means, i.e. without the use of stop or register wall}
- B65H 2220/09: indicating that several of an entity are present
- B65H 2301/331: Skewing, correcting skew, i.e. changing slightly orientation of material
- B65H 2404/14: Roller pairs
- B65H 2511/24: Irregularities, e.g. in orientation or skewness
- B65H 2513/20: Acceleration or deceleration
- B65H: HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES

## Abstract

A sheet conveying apparatus includes a skew correction unit configured to correct the skew of a sheet while conveying the sheet, controls the skew correction unit to correct the rough skew of the sheet by a first skew correction operation, and accurately correct the reduced skew of the sheet by a second skew correction operation.

## Claims

### Claim 1

A sheet conveying apparatus comprising:
a skew detection unit configured to detect a skew of a sheet; and
a skew correction unit including two sets of roller pairs for conveying the sheet by independently rotating, disposed orthogonal to a sheet conveying direction, configured to convey and rotate the sheet to correct the skew of the sheet by a difference of sheet conveying velocity of the respective roller pairs based on a detection by the skew detection unit,
wherein the skew correction unit performs a first skew correction operation and a second skew correction operation after the first skew correction operation, and a difference of the sheet conveying velocity for the second skew correction operation is smaller than a difference of the sheet conveying velocity for the first skew correction operation.

### Claim 2

A sheet conveying apparatus comprising:
a skew detection unit configured to detect a skew of a sheet; and
a skew correction unit including two sets of roller pairs for conveying the sheet by independently rotating, disposed orthogonal to a sheet conveying direction, configured to convey and rotate the sheet to correct the skew of the sheet by a difference of sheet conveying velocity of the respective roller pairs based on a detection by the skew detection unit,
wherein the skew correction unit performs a first skew correction operation and a second skew correction operation after the first skew correction operation, and performs the first skew correction operation and the second skew correction operation such that a correction time for the second skew correction operation is longer than a correction time for the first skew correction operation.

### Claim 3

A sheet conveying apparatus comprising:
a skew detection unit configured to detect a skew of a sheet; and
a skew correction unit including two sets of roller pairs for conveying the sheet by independently rotating, disposed orthogonal to a sheet conveying direction, configured to convey and rotate the sheet to correct the skew of the sheet by a difference of sheet conveying velocity of the respective roller pairs based on a detection by the skew detection unit,
wherein the skew correction unit performs a first skew correction operation and a second skew correction operation after the first skew correction operation, and a first skew correction area for the first skew correction operation and a second skew correction area for the second skew correction operation are formed on driving rollers of the respective roller pairs, and the first skew correction area is set so as to have a greater contact area as to the sheet, and lower surface accuracy as compared with the second skew correction area.

### Claim 4

An image forming apparatus comprising:
a sheet conveying apparatus including,
a skew detection unit configured to detect a skew of a sheet;
a skew correction unit including two sets of roller pairs for conveying the sheet by independently rotating, disposed orthogonal to a sheet conveying direction, configured to convey and rotate the sheet to correct the skew of the sheet by a difference of sheet conveying velocity of the respective roller pairs based on a detection by the skew detection unit,
wherein the skew correction unit performs a first skew correction operation and a second skew correction operation after the first skew correction operation, and a difference of the sheet conveying velocity for the second skew correction operation is smaller than a difference of the sheet conveying velocity for the first skew correction operation; and
an image forming portion configured to form an image on a sheet conveyed by the sheet conveying apparatus.

### Claim 5

An image forming apparatus comprising:
a sheet conveying apparatus including,
a skew detection unit configured to detect a skew of a sheet; and
a skew correction unit including two sets of roller pairs for conveying the sheet by independently rotating, disposed orthogonal to a sheet conveying direction, configured to convey and rotate the sheet to correct the skew of the sheet by a difference of sheet conveying velocity of the respective roller pairs based on a detection by the skew detection unit,
wherein the skew correction unit performs a first skew correction operation and a second skew correction operation after the first skew correction operation, and performs the first skew correction operation and the second skew correction operation such that a correction time for the second skew correction operation is longer than a correction time for the first skew correction operation; and
an image forming portion configured to form an image on a sheet conveyed by the sheet conveying apparatus.

### Claim 6

An image forming apparatus comprising:
a sheet conveying apparatus including,
a skew detection unit configured to detect a skew of a sheet; and
a skew correction unit including two sets of roller pairs for conveying the sheet by independently rotating, disposed orthogonal to a sheet conveying direction, configured to convey and rotate the sheet to correct the skew of the sheet by a difference of sheet conveying velocity of the respective roller pairs based on a detection by the skew detection unit,
wherein the skew correction unit performs a first skew correction operation and a second skew correction operation after the first skew correction operation, and a first skew correction area for the first skew correction operation and a second skew correction area for the second skew correction operation are formed on driving rollers of the respective roller pairs, and the first skew correction area is set so as to have a greater contact area as to the sheet, and lower surface accuracy as compared with the second skew correction area; and
an image forming portion configured to form an image on a sheet conveyed by the sheet conveying apparatus.