Image forming apparatus

Patent metadata

Field	Value
Publication number	US-11487228-B2
Application number	US-202117372768-A
Country	US
Kind code	B2
Filing date	Jul 12, 2021
Priority date	Jul 15, 2020
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

An image forming apparatus includes a control unit configured to execute a first mode and a second mode. The first mode is a mode in which a toner image is formed on a sheet at a time when a sheet passes through an image formation position for a first time after detecting a property of the sheet by a detection unit. Wherein the second mode is a mode in which a toner image is not formed on a sheet at the time when the sheet passes through the image formation position for the first time after detecting the property of the sheet by the detection unit and is formed on the sheet at a time when the sheet is conveyed via the second conveyance path and passes through the image formation position for a second time.

First claim

What is claimed is:

1. An image forming apparatus comprising:
a conveyance unit configured to convey a sheet;
a first conveyance path on which the sheet is conveyed by the conveyance unit;
a detection unit configured to detect a property of the sheet conveyed along the first conveyance path;
an image forming unit configured to form an unfixed toner image onto the sheet detected by the detection unit at an image formation position on the first conveyance path;
a fixing unit configured to fix the toner image on the sheet by heating and pressing the sheet on which the toner image is formed by the image forming unit;
a second conveyance path branching from the first conveyance path at a position downstream of the fixing unit in a sheet conveyance direction and joining the first conveyance path at a position upstream of the image forming unit in the sheet conveyance direction; and
a control unit configured to execute a first mode and a second mode,
wherein the first mode is a mode in which a toner image is formed on a sheet at a time when the sheet passes through the image formation position for a first time after detecting the property of the sheet by the detection unit, and
wherein the second mode is a mode in which a toner image is not formed on a sheet at the time when the sheet passes through the image formation position for the first time after detecting the property of the sheet by the detection unit and is formed on the sheet at a time when the sheet is conveyed via the second conveyance path and passes through the image formation position for a second time,
wherein, in the second mode, the control unit is configured to switch a sheet conveyance speed from a first conveyance speed to a second conveyance speed different from the first conveyance speed, and
wherein, in the second mode, the control unit is configured to switch the sheet conveyance speed from the first conveyance speed to the second conveyance speed during a time when the sheet is being conveyed on the second conveyance path.

2. The image forming apparatus according to claim 1 ,
wherein, based on a detection of a predetermined property of the sheet by the detection unit, the control unit is configured to change a fixing temperature of the fixing unit from a first temperature to a second temperature different from the first temperature.

3. The image forming apparatus according to claim 2 ,
wherein the second temperature is higher than the first temperature.

4. The image forming apparatus according to claim 1 ,
wherein the second conveyance speed is slower than the first conveyance speed.

5. The image forming apparatus according to claim 1 ,
wherein, in a case performing the second mode with respect to a first sheet, the control unit is configured to control the conveyance unit to start a conveyance of a second sheet conveyed subsequent to the first sheet after the sheet conveyance speed of the first sheet has been switched from the first conveyance speed to the second conveyance speed.

6. The image forming apparatus according to claim 1 ,
further comprising a discharge unit configured to discharge the sheet,
wherein, in the case performing the second mode with respect to the first sheet, the control unit is configured to control the conveyance unit to start the conveyance of the second sheet at the second conveyance speed after the first sheet has been discharged.

7. The image forming apparatus according to claim 1 ,
wherein the image forming unit comprises
an image bearing member that rotates,
a charge unit configured to charge the image bearing member by applying a charge voltage,
an exposing unit configured to form an electrostatic latent image by exposing the image bearing member which has been charged,
a developing unit configured to develop the electrostatic latent image on the image bearing member to a toner image by developer, and
a transfer unit configured to transfer the toner image on the image bearing member to the sheet, and

wherein, in the second mode, the control unit is configured to restrict formation of the toner image onto the sheet passing through the image formation position for the first time by preventing the exposing unit from exposing the image bearing member.

8. The image forming apparatus according to claim 1 ,
wherein the image forming unit comprises
an image bearing member that rotates,
a charge unit configured to charge the image bearing member by applying a charge voltage,
an exposing unit configured to form an electrostatic latent image by exposing the image bearing member which has been charged,
a developing unit configured to develop the electrostatic latent image on the image bearing member to a toner image by developer, and
a transfer unit configured to transfer the toner image on the image bearing member to the sheet, and

wherein, in the second mode, the control unit is configured to switch the sheet conveyance speed from the first conveyance speed to the second conveyance speed and configured to bring the exposing unit to start an exposure of the image bearing member in a state where the sheet conveyance speed has been switched from the first conveyance speed to the second conveyance speed.

9. The image forming apparatus according to claim 1 ,
wherein the image forming unit comprises
an image bearing member that rotates,
a charge unit configured to charge the image bearing member by applying a charge voltage,
an exposing unit configured to form an electrostatic latent image by exposing the image bearing member which has been charged,
a developing unit configured to develop the electrostatic latent image on the image bearing member to a toner image by developer, and
a transfer unit configured to transfer the toner image on the image bearing member to the sheet, and

wherein, in the second mode, the control unit is configured to restrict transference of the toner image on the image bearing member to the sheet by applying a voltage of a same polarity as the toner image by the transfer unit.

10. The image forming apparatus according to claim 1 ,
further comprising a single motor configured to drive the conveyance unit and the image forming unit.

11. The image forming apparatus according to claim 1 ,
wherein the detection unit is configured to detect at least one of a grammage and a surface property as the property of the sheet.

12. The image forming apparatus according to claim 1 ,
wherein the detection unit comprises an output part outputting a sound wave to the sheet and an input part to which the sound wave is input.

13. The image forming apparatus according to claim 1 ,
wherein, even in a case where the detection unit has detected that the property of the conveyed sheet is a predetermined property, the control unit is configured to perform the first mode and not to perform the second mode in a case where an image coverage of the toner image formed on the sheet is less than a predetermined ratio.

14. The image forming apparatus according to claim 1 ,
wherein, even in a case where the detection unit has detected that the property of the conveyed sheet is a predetermined property, the control unit is configured to perform the first mode and not to perform the second mode in a case where a maximum density of the toner image formed on the sheet is less than a predetermined density.

15. An image forming apparatus comprising:
a conveyance unit configured to convey a sheet;
an image forming unit configured to form an unfixed toner image onto the sheet conveyed by the conveyance unit;
a fixing unit configured to fix the toner image on the sheet by h

Assignees

• Canon Kk

Inventors

• Kurata Munehito
• Mochizuki Keisuke
• Fujimoto Tetsuichiro

Classifications

• G03G15/2028 Primary

  with means for handling the copy material in the fixing nip, e.g. introduction guides, stripping means · CPC title

• G03G15/2039

  with means for controlling the fixing temperature · CPC title

• G03G15/5029

  by measuring the copy material characteristics, e.g. weight, thickness · CPC title