Image forming apparatus

Patent metadata

Field	Value
Publication number	US-11260674-B2
Application number	US-202016779089-A
Country	US
Kind code	B2
Filing date	Jan 31, 2020
Priority date	Feb 8, 2019
Publication date	Mar 1, 2022
Grant date	Mar 1, 2022

Abstract

An image forming apparatus includes a sheet conveyance portion, a recording portion, a sheet detection portion, and a control portion. In a duplex printing including a first and a second process of printing on a first surface and a second surface of the sheet, in the first process, the control portion calculates a center position of the sheet based on an edge position of the sheet on one side in the width direction and size information of the sheet, prints a first image on the first surface such that the first image is centered on the center position calculated, and prints a reference marker on the first surface. In the second process, the control portion calculates a correction magnification ratio based on a difference between a reading position and the printing position of the reference marker, and corrects a size and a printing position of a second image.

First claim

What is claimed is:

1. An image forming apparatus comprising:
a sheet conveyance portion which conveys a sheet;
a recording portion which is arranged facing the sheet conveyance portion and ejects ink to a printing surface of the sheet conveyed by the sheet conveyance portion;
a sheet detection portion
which is arranged on an upstream side of the recording portion with respect to a sheet conveyance direction,
which is capable of reading a reading surface of the sheet which is opposite to the printing surface, and
which detects an edge position of the sheet on one side of the sheet in a width direction intersecting the sheet conveyance direction; and

a control portion which controls ink ejection from the recording portion and prints an image on the printing surface of the sheet,
wherein,
in a duplex printing including a first process through which a first image is printed on a first surface of the sheet as the printing surface and a second process through which the sheet is turned over and a second image is printed on a second surface of the sheet as the printing surface,
in the first process, the control portion
calculates a center position of the sheet based on the edge position of the sheet on the one side of the sheet in the width direction thereof having been detected by the sheet detection portion and size information of the sheet having been obtained in advance,
prints the first image on the first surface such that the first image is centered on the center position calculated, and
prints a reference marker at a predetermined printing position on the first surface, and,

in the second process, the control portion reads the reference marker by means of the sheet detection portion,
calculates a correction magnification ratio based on a difference between a reading position of the reference marker having been read and the printing position of the reference marker, and
corrects a size of the second image and a printing position of the second image in the width direction using the correction magnification ratio.

2. The image forming apparatus according to claim 1 ,
wherein
the control portion
calculates an expansion-contraction ratio of the sheet using a ratio d 2 /d 1 between a distance d 1 from the edge position to the reference marker in printing the reference marker on the first surface of the sheet and a distance d 2 from the edge position detected after the sheet is turned over to the reference marker, and,
determines a correction magnification ratio of the second image based on the expansion-contraction ratio of the sheet calculated.

3. The image forming apparatus according to claim 2 ,
wherein
the control portion
corrects a distance from the edge position to the center position by multiplying a distance from the edge position on the one side to the center position of the sheet in the width direction thereof with the expansion-contraction ratio of the sheet,
aligns the center of the second image whose size is corrected by the correction magnification with the corrected center position, and
prints the second image on the second surface.

4. The image forming apparatus according to claim 1 ,
wherein
the reference marker is printed on the first surface, at a position between the center position and an edge position on other side of the sheet opposite from the one side in the width direction thereof.

5. The image forming apparatus according to claim 4 ,
wherein,
in a case where the first image is printed so as to overlap with the printing position of the reference marker, the reference marker is formed as a white reference marker by providing, in the first image, a pixel at which the ink is not ejected.

6. The image forming apparatus according to claim 1 ,
wherein
as the reference marker, a plurality of reference markers are printed along the sheet conveyance direction at positions equidistant from the edge position on the one side of the sheet in the width direction.

7. The image forming apparatus according to claim 1 ,
wherein
the reference marker is printed in the ink of a lightest color of all colors of the ink ejected in the recording portion.

Assignees

• Kyocera Document Solutions Inc

Inventors

• Kawai Hisaji

Classifications

• B65H2511/24

  Irregularities, e.g. in orientation or skewness · CPC title

• B41J2/07

  characterised by jet control (B41J2/205 takes precedence) · CPC title

• B41J11/003

  Paper-size detection, i.e. automatic detection of the length and/or width of copy material · CPC title

• B41J11/0095

  Detecting means for copy material, e.g. for detecting or sensing presence of copy material or its leading or trailing end · CPC title

• B41J11/46

  by marks or formations on the paper being fed · CPC title