US-12619183-B2 - Control for conveying a continuous sheet in an image forming apparatus

Abstract

Provided is an image forming apparatus capable of printing on continuous sheet. The image forming apparatus includes: a fixing section that fixes an image on an unfixed surface of the continuous sheet while conveying the continuous sheet by a fixing nip; a downstream-side conveyance section that is disposed on a downstream side of the fixing section in a sheet conveyance direction and conveys the continuous sheet by a downstream-side conveyance nip; a detection section that detects a physical amount related to a thermal expansion state of a fixing member that forms the fixing nip; and a control section that controls driving aspects of the fixing section and the downstream-side conveyance section based on a detection result by the detection section.

Inventors

• Tsutomu SAKAMAKI

Assignees

• Konica Minolta, Inc.

Dates

Publication Date

20260505

Application Date

20240620

Priority Date

20230623

Claims (18)

1. 1 . An image forming apparatus capable of printing on continuous sheet, the image forming apparatus comprising: a fixing section that fixes an image on an unfixed surface of the continuous sheet while conveying the continuous sheet by a fixing nip, wherein the fixing section includes a pressure-contact/separation section that brings fixing members that form the fixing nip into pressure contact with each other and that separates the plurality of fixing members from each other; a downstream-side conveyance section that is disposed on a downstream side of the fixing section in a sheet conveyance direction and conveys the continuous sheet by a downstream-side conveyance nip; a detection section that detects a physical amount related to a thermal expansion state of a fixing member of the fixing members that form the fixing nip; and a control section that controls a driving aspect of at least one of the fixing section and/or the downstream-side conveyance section based on a detection result by the detection section, wherein a driving start timing of a conveyance member in the downstream-side conveyance section is set to be a time after a start of a pressure-contact operation of the pressure-contact/separation section and a driving stop timing of the conveyance member in the downstream-side conveyance section is set to be a time after a start of a separation operation of the pressure-contact/separation section, and the control section performs an adjustment of the driving start timing of the conveyance member in the downstream-side conveyance section to an earlier time after the start of the pressure-contact operation as the physical amount indicates that a thermal expansion amount of the fixing member increases, an adjustment of the driving stop timing of the conveyance member in the downstream-side conveyance section to a later time after the start of the separation operation as the physical amount indicates that a thermal expansion amount of the fixing member increases, or both.
2. 2 . The image forming apparatus according to claim 1 , wherein: the control section shifts, at a conveyance start, one of the plurality of fixing members from a separated state to a pressure-contact state while driving the one of the plurality of fixing members, and shifts, at a conveyance stop, the one of the plurality of fixing members from the pressure-contact state to the separated state while driving the one of the plurality of fixing members.
3. 3 . The image forming apparatus according to claim 2 , wherein the control section shifts, at the conveyance start, from the separated state to the pressure-contact state after a difference between a sheet length of the continuous sheet and a conveyance path length becomes equal to or less than a predetermined amount, the continuous sheet being passed between the fixing nip and the downstream-side conveyance nip.
4. 4 . The image forming apparatus according to claim 2 , wherein the detection section detects a separation distance between the fixing members forming the fixing nip.
5. 5 . The image forming apparatus according to claim 2 , wherein the detection section detects driving torque of one of the fixing members or driving torque of the pressure-contact/separation section.
6. 6 . The image forming apparatus according to claim 1 , wherein the control section controls driving speeds of a conveyance member in the downstream-side conveyance section at a conveyance start and at a conveyance stop.
7. 7 . The image forming apparatus according to claim 6 , wherein the control section controls a rising speed of the conveyance member in the downstream-side conveyance section faster and controls a falling speed of the conveyance member in the downstream-side conveyance section slower as a thermal expansion amount of the fixing member is larger.
8. 8 . The image forming apparatus according to claim 1 , wherein the detection section detects a surface temperature of the fixing member, a temperature of a core metal of the fixing member, and an ambient temperature within the fixing section.
9. 9 . The image forming apparatus according to claim 1 , wherein the detection section detects an outer diameter of the fixing member.
10. 10 . The image forming apparatus according to claim 1 , wherein the control section controls the driving aspect such that a conveyance start timing in the downstream-side conveyance section coincides with a conveyance start timing in the fixing section.
11. 11 . The image forming apparatus according to claim 1 , wherein the control section controls the driving aspect such that a conveyance stop timing in the downstream-side conveyance section is identical to or later than a conveyance stop timing in the fixing section.
12. 12 . The image forming apparatus according to claim 1 , wherein the control section controls the driving aspect of the fixing section and the driving aspect of the downstream-side conveyance section based on media information of the continuous sheet in use in addition to the detection result.
13. 13 . The image forming apparatus according to claim 12 , wherein the media information includes at least one of a material, a melting point, a thickness, a basis weight, stiffness, and/or a friction coefficient of the continuous sheet.
14. 14 . The image forming apparatus according to claim 13 , comprising a media information detection section that detects a physical property of the continuous sheet as the media information.
15. 15 . The image forming apparatus according to claim 1 , wherein the control section corrects, according to durability of the fixing section and durability of the downstream-side conveyance section, the driving aspect controlled based on the detection result.
16. 16 . The image forming apparatus according to claim 15 , wherein the control section sets a correction amount by comparing the driving aspect controlled based on the detection result with an actual driving aspect.
17. 17 . A conveyance method in an image forming apparatus capable of printing on continuous sheet, the conveyance method comprising: conveying the continuous sheet by a fixing nip that fixes an image on an unfixed surface of the continuous sheet, the fixing nip being formed by fixing members; conveying the continuous sheet by a downstream-side conveyance nip disposed on a downstream side of the fixing nip in a sheet conveyance direction; detecting a physical amount related to a thermal expansion state of a fixing member of the fixing members that form the fixing nip; controlling a driving aspect of at least one of a fixing section and/or a downstream-side conveyance section based on the detected physical amount related to the thermal expansion state, the fixing section being a fixing section in which the fixing nip is disposed, the downstream-side conveyance section being a downstream-side conveyance section in which the downstream side conveyance nip is disposed; and controlling a pressure-contact/separation section to bring the fixing members that form the pressure nip into pressure contact with each other and to separate the fixing members from each other, wherein a driving start timing of a conveyance member in the downstream-side conveyance section is set to be a time after a start of a pressure-contact operation of the pressure-contact/separation section and a driving stop timing of the conveyance member in the downstream-side conveyance section is set to be a time after a start of a separation operation of the pressure-contact/separation section, and the step of controlling a driving aspect includes adjusting the driving start timing of the conveyance member in the downstream-side conveyance section to an earlier time after the start of the pressure-contact operation as the physical amount indicates that a thermal expansion amount of the fixing member increases, adjusting the driving stop timing of the conveyance member in the downstream-side conveyance section to a later time after the start of the separation operation as the physical amount indicates that a thermal expansion amount of the fixing member increases, or both.
18. 18 . A non-transitory computer-readable recording medium storing a program, the program causing a computer of an image forming apparatus to execute predetermined processing, the image forming apparatus capable of printing on continuous sheet, wherein the predetermined processing includes: conveying the continuous sheet by a fixing nip that fixes an image on an unfixed surface of the continuous sheet, the fixing nip being formed by fixing members; conveying the continuous sheet by a downstream-side conveyance nip disposed on a downstream side of the fixing nip in a sheet conveyance direction; detecting a physical amount related to a thermal expansion state of a fixing member that forms the fixing nip; controlling a driving aspect of at least one of a fixing section, in which the fixing nip is disposed, and a downstream-side conveyance section, in which the downstream-side conveyance nip is disposed, based on the detected physical amount related to the thermal expansion state; and controlling a pressure-contact/separation section to bring the fixing members that form the pressure nip into pressure contact with each other and to separate the fixing members from each other, wherein a driving start timing of a conveyance member in the downstream-side conveyance section is set to be a time after a start of a pressure-contact operation of the pressure-contact/separation section and a driving stop timing of the conveyance member in the downstream-side conveyance section is set to be a time after a start of a separation operation of the pressure-contact/separation section, and the controlling a driving aspect includes adjusting the driving start timing of the conveyance member in the downstream-side conveyance section to an earlier time after the start of the pressure-contact operation as the physical amount indicates that a thermal expansion amount of the fixing member increases, adjusting the driving stop timing of the conveyance member in the downstream-side conveyance section to a later time after the start of the separation operation as the physical amount indicates that a thermal expansion amount of the fixing member increases, or both.

Description

CROSS REFERENCE TO RELATED APPLICATIONS The entire disclosure of Japanese Patent Application No. 2023-103657, filed on Jun. 23, 2023, is incorporated herein by reference in its entirety. BACKGROUND Technological Field The present invention relates to an image forming apparatus, a conveyance method, and a non-transitory computer-readable recording medium storing a program. Description of Related Art In an image forming apparatus (a printer, a copying machine, a facsimile, or the like) using an electrophotographic process technology, laser light based on image data is emitted (exposed) to a uniformly charged photoreceptor so that an electrostatic latent image is formed on a surface of the photoreceptor. Then, a toner is supplied to the photoreceptor, whereby the electrostatic latent image is visualized as a toner image. The toner image is, for example, indirectly transferred onto a recording material via an intermediate transfer member, and then heated and pressurized in a fixing section. Through the above process, an image is formed on the recording material. In addition to flat sheet, continuous sheet such as machine-glazed sheet may be used as the recording material. The above-described electrophotographic image forming apparatus includes conveyance nips at a plurality of positions on a conveyance path of the recording material. The conveyance nip includes a fixing nip of the fixing section. The conveyance nip is formed by a pair of conveyance members. In particular, the fixing nip is formed by a pair of fixing members (for example, a fixing roller and a pressure roller). One of the pair of conveyance members (the fixing member in the case of the fixing nip) is formed by a rotatably drivable driving roller. By passing a recording material through the conveyance nip, the rotational force of the driving roller is transmitted to the recording material, and the recording material is conveyed. In the case of printing on continuous sheet, the continuous sheet is passed through the fixing nip of the fixing section and a conveyance nip of a downstream-side conveyance section (hereinafter, referred to as “downstream-side conveyance nip”) disposed on the downstream of the fixing section in the sheet conveyance direction. In the fixing section, usually, a pair of fixing members forming the fixing nip is held in a state of being separated from each other so that damage such as discoloration does not occur on the continuous sheet due to heat transmission from the fixing members during non-printing in which printing on the continuous sheet is not performed, and is brought into pressure contact with each other at the start of printing. At the start of printing, the conveyance of the continuous sheet is started at a timing when a fixing nip having a predetermined width is formed in a process in which the fixing member shifts from a separated state to a pressure-contact state. Further, at the end of printing, in the process in which the fixing member shifts from the pressure-contact state to the separated state, the nip width becomes equal to or smaller than the predetermined width, and the conveyance of the continuous sheet is stopped at a timing when the fixing nip is released. Here, in a case where a conveyance start timing of the continuous sheet by the fixing nip (timing at which continuous sheet starts moving) is earlier than a conveyance start timing of the continuous sheet by the downstream-side conveyance nip, slack occurs in the continuous sheet, and a failure in which the continuous sheet winds around the fixing member may occur. In addition, in a case where a conveyance stop timing of the continuous sheet by the fixing nip is later than a conveyance stop timing of the continuous sheet by the downstream-side conveyance nip, slack also occurs in the continuous sheet, and a failure in which the continuous sheet winds around the fixing member may occur. Hereinafter, the conveyance start timing and the conveyance stop timing in the fixing section and the conveyance start timing and the conveyance stop timing in the downstream-side conveyance section are referred to as “fixing-side conveyance start timing”, “fixing-side conveyance stop timing”, “downstream-side conveyance start timing”, and “downstream-side conveyance stop timing”, respectively. Furthermore, in a case where the downstream-side conveyance start timing is earlier than the fixing-side conveyance start timing, the continuous sheet cannot be conveyed only by the downstream-side conveyance nip, and the continuous sheet may slip at the downstream-side conveyance nip, causing abnormal noise. Such a failure is likely to occur particularly in the case of using continuous sheet having a large sheet thickness and a large conveyance load. Conventionally, the operations of the respective driving rollers are controlled such that abnormal noise due to slack or slip of the continuous sheet does not occur in the fixing section and the downstream-side conveyance sectio