Image forming apparatus and image forming method

Patent metadata

Field	Value
Publication number	US-11945677-B2
Application number	US-202117528195-A
Country	US
Kind code	B2
Filing date	Nov 17, 2021
Priority date	Nov 27, 2020
Publication date	Apr 2, 2024
Grant date	Apr 2, 2024

Abstract

An image forming apparatus includes a sheet conveyance device; an image forming device including a sheet conveyance roller and a pressure roller; a memory; and a controller. The memory stores profile data indicating variation in conveyance amount in a circumferential direction due to eccentricity of the conveyance roller. The controller calculates, in intermittent conveyance processing, a correction value based on corresponding profile data for each of positions included in a width of an image to be formed in next image forming processing, the correction value being a difference between a predetermined conveyance amount and an actual conveyance amount; corrects a reference amount of rotation by a representative value of calculated correction values to calculate a corrected amount of rotation, the reference amount being an ideal amount of rotation of the conveyance roller that conveys a sheet by the predetermined conveyance amount; and rotates the conveyance roller by the corrected amount.

First claim

The invention claimed is:

1. An image forming apparatus, comprising:
a sheet conveyance device including a sheet conveyance roller and a pressure roller configured to hold and convey a sheet between the sheet conveyance roller and the pressure roller;
an image forming device configured to form an image on the sheet conveyed by the sheet conveyance device;
a memory configured to store profile data for each of a plurality of positions in an axial direction of the sheet conveyance roller, the profile data indicating a variation in conveyance amount in a circumferential direction due to eccentricity of the sheet conveyance roller; and
a controller configured to control the sheet conveyance device and the image forming device,
wherein the controller is configured to repeatedly execute intermittent conveyance processing and image forming processing,
the intermittent conveyance processing including rotating the sheet conveyance roller to cause the sheet conveyance device to convey the sheet by a predetermined conveyance amount; and
the image forming processing including causing the image forming device to form an image on an area of the sheet having been conveyed to a position facing the image forming device by the intermittent conveyance processing, and

wherein the controller is configured to:
calculate, in the intermittent conveyance processing, a correction value based on corresponding profile data for each of a plurality of positions included in a width of an image to be formed on the sheet in next image forming processing, the correction value being a difference between the predetermined conveyance amount and an actual conveyance amount;
correct a reference amount of rotation by a representative value of a plurality of calculated correction values to calculate a corrected amount of rotation, the reference amount of rotation being an ideal amount of rotation of the sheet conveyance roller that conveys the sheet by the predetermined conveyance amount; and
rotate the sheet conveyance roller by the corrected amount of rotation calculated.

2. The image forming apparatus according to claim 1 ,
wherein, in a case of forming images in a plurality of separate areas in a width direction of the sheet in the next image forming processing, the controller is configured to calculate the correction value for each position included in a width of each of the images.

3. The image forming apparatus according to claim 1 ,
wherein the representative value is a weighted average value of the plurality of correction values, and
wherein the controller is configured to set a first weight of a correction value for a position included in a width of an image having a density equal to or larger than a threshold value to be larger than a second weight of a correction value for a position included in a width of an image having a density smaller than the threshold value, to calculate the weighted average value.

4. The image forming apparatus according to claim 1 , further comprising:
a reference point sensor configured to detect a reference point in the circumferential direction of the sheet conveyance roller; and
a rotation amount sensor configured to detect an amount of rotation of the sheet conveyance roller,
wherein the controller is configured to:
specify, in the intermittent conveyance processing, a start point abutting the sheet at a start of the intermittent conveyance processing and an end point abutting the sheet at an end of the intermittent conveyance processing in the circumferential direction of the sheet conveyance roller, based on a combination of detection results of the reference point sensor and the rotation amount sensor; and
calculate the correction value between the start point and the end point specified by the controller, based on the profile data.

5. The image forming apparatus according to claim 4 ,
wherein the profile data is a sine curve obtained by approximating a variation in conveyance amount at points in the circumferential direction of the conveyance roller, and
wherein the controller is configured to calculate, as the correction value, a difference between an amplitude of the sine curve at the start point and an amplitude of the sine curve at the end point.

6. An image forming method to be executed by an image forming apparatus that includes an image forming device and a sheet conveyance device, the sheet conveyance device including a sheet conveyance roller and a pressure roller configured to hold and convey a sheet between the sheet conveyance roller and the pressure roller,
the image forming method comprising:
repeatedly executing intermittent conveyance processing and image forming processing,
the intermittent conveyance processing including rotating the sheet conveyance roller to convey the sheet by a predetermined conveyance amount; and
the image forming processing including causing the image forming device to form an image on an area of the sheet having been conveyed to a position facing the image forming device by the intermittent conveyance processing;

calculating, in the intermittent conveyance processing, a correction value based on corresponding profile data for each of a plurality of positions included in a width of an image to be formed on the sheet in next image forming processing, the correction value being a difference between the predetermined conveyance amount and an actual conveyance amount, the corresponding profile data indicating a variation in conveyance amount in a circumferential direction due to eccentricity of the sheet conveyance roller;
correcting a reference amount of rotation by a representative value of a plurality of calculated correction values to calculate a corrected amount of rotation, the reference amount of rotation being an ideal amount of rotation of the sheet conveyance roller that conveys the sheet by the predetermined conveyance amount; and
rotating the sheet conveyance roller by the corrected amount of rotation calculated.

Assignees

• Masunaga Suguru
• Ricoh Co Ltd

Inventors

• Masunaga Suguru

Classifications

• B65H43/04 Primary

  detecting, or responding to, presence of faulty articles (B65H43/08 takes precedence; diverting faulty articles from main streams B65H29/62) · CPC title

• B41J11/42

  Controlling {printing material conveyance for accurate alignment of the printing material with the printhead; Print registering} · CPC title

• B41J29/38

  Drives, motors, controls or automatic cut-off devices for the entire printing mechanism · CPC title

• B65H20/02

  by friction roller · CPC title

• B65H2513/40

  Movement · CPC title