CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application Nos. 2017-230434, filed on Nov. 30, 2017, and 2018-217148, filed on Nov. 20, 2018, in the Japan Patent Office, the entire disclosure of each of which is hereby incorporated by reference herein.

BACKGROUND

Technical Field

This disclosure relates to a sheet conveying device that feeds a conveyance target medium, an image forming apparatus including the sheet conveying device, a method of conveying a conveyance target medium, and a method of forming an image on a conveyance target medium using the method of conveying the conveyance target medium.

Related Art

Various sheet conveying devices that convey a conveyance target medium are known to convey sheets such as papers and original documents in an image forming apparatus such as a copier and a printer.

In general, such sheet conveying devices are known that, when a sheet is conveyed to an image forming device or an image transfer device, the sheet under conveyance is abutted against a nip region of a pair of sheet conveying rollers that is stopped so as to correct an angular displacement of the sheet, and then the pair of sheet conveying rollers starts rotating at a predetermined timing to convey the sheet to a target position. However, a method of abutting the sheet to the nip region of the pair of sheet conveying rollers causes the sheet to stop temporarily, and therefore the productivity degrades (the image forming speed decreases).

In order to address this inconvenience and correct positional deviations of a sheet without degrading the productivity, a known sheet conveying device has been proposed that a pair of rollers is driven in a direction opposite to the direction of a positional deviation of the sheet while conveying the sheet so that the positional deviation of the sheet is corrected without stopping conveyance of the sheet.

However, when the positional deviation of a sheet is corrected while the sheet is being conveyed, the position of the leading end of the sheet changes, and therefore an amount of time that the leading end of the sheet reaches a predetermined target position varies. Consequently, if the sheet is conveyed at a predetermined conveying speed, the timing at which the sheet reaches the target position is shifted, which causes an inconvenience that the sheet cannot be conveyed with high accuracy.

In order to solve the shift of the timing caused by the correction of the positional deviation of the sheet, the known sheet conveying device calculates the position of the leading end of the sheet after the correction of the positional deviation of the sheet based on the positional deviation amount of the sheet, and the sheet conveying speed is adjusted based on the calculation result.

However, the known sheet conveying device detects the angular displacement of the sheet for one time, and therefore the correction of the angular and lateral displacements of the sheet is also performed for one time. Consequently, when the sheet further shifts after the correction of the positional deviation of the sheet the known sheet conveying device cannot convey the sheet with high accuracy.

SUMMARY

At least one aspect of this disclosure provides a sheet conveying device including a position detector, a position adjuster, and circuitry. The position detector is configured to detect a position of a side end of a conveyance target medium. The position adjuster is configured to, based on a detection of the position of the side end of the conveyance target medium detected by the position detector, move in at least one of a width direction of the conveyance target medium and a rotation direction of the conveyance target medium within a plane of conveyance of the conveyance target medium and repeatedly adjust the position of the side end of the conveyance target medium, while the conveyance target medium is being conveyed. The circuitry is configured to change a conveying speed of the conveyance target medium, according to a change of the position of the side end of the conveyance target medium after adjusted by the position adjuster.

Further, at least one aspect of this disclosure provides an image forming apparatus including the above-described sheet conveying device.

Further, at least one aspect of this disclosure provides a sheet conveying device including a plurality of position sensors, a position adjuster, and circuitry. The plurality of position sensors are configured to detect a position of a side end of a conveyance target medium. The position adjuster is configured to, based on a detection of the position of the side end of the conveyance target medium detected by the plurality of position sensors, move in at least one of a width direction of the conveyance target medium and a rotation direction of the conveyance target medium within a plane of conveyance of the conveyance target medium and adjust the position of the side end of the conveyance target medium, while the conveyance target medium is being conveyed. The circuitry is configured to change a conveying speed of the conveyance target medium, according to a change of the position of the side end of the conveyance target medium after adjusted by the position adjuster.

Further, at least one aspect of this disclosure provides an image forming apparatus including the above-described sheet conveying device.

Further, at least one aspect of this disclosure provides a method of conveying a conveyance target medium including detecting a position of a side end of a conveyance target medium, moving in at least one of a width direction of the conveyance target medium and a rotation direction of the conveyance target medium within a plane of conveyance of the conveyance target medium while the conveyance target medium is being conveyed, based on a detection of the position of the conveyance target medium, adjusting the position of the side end of the conveyance target medium repeatedly while the conveyance target medium is being conveyed, based on the detection of the position of the conveyance target medium, and changing a conveying speed of the conveyance target medium, according to a change of the position of the side end of the conveyance target medium after adjusted by the adjusting.

Further, at least one aspect of this disclosure provides a method of forming an image on a conveyance target medium using the above-described method of conveying the conveyance target medium to convey the conveyance target medium and form an image on the conveyance target medium.

