Image forming apparatus and method of cleaning image forming apparatus

Abstract

To provide an image forming apparatus capable of sufficiently collecting, by a web, an adhering substance collected from a fixing roller to a cleaning roller in an image forming job regardless of an image forming mode, thereby preventing the occurrence of an image defect.SOLUTION: An image forming apparatus includes: a cleaning roller for collecting an adhering substance adhering to a fixer for fixing a toner image onto a recording medium; a web feeder that feeds, to the cleaning roller, a web for collecting the adhering substance adhering to the cleaning roller; and a controller that controls operation of the web feeder. The controller calculates, on the basis of job information of image formation, a required feed amount of the web required for collecting the adhering substance adhering to the cleaning roller, and when the required feed amount is greater than a feed amount of the web that can be fed during execution of image formation of a job related to the job information, feeds the web to the cleaning roller after completion of the image formation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus and a cleaning method for an image forming apparatus. [Background technology]

[0002] Some image forming apparatuses are equipped with a fixing roller for fixing a toner image to a recording medium. Such image forming apparatuses are also equipped with a cleaning roller for cleaning the surface of the fixing roller. Patent Document 1 below, which describes a technique related to such image forming apparatuses, describes a technique in which, when a borderless printing mode is executed, the timing for cleaning the cleaning member itself is determined based on image information corresponding to the toner image around the edge of the recording material that extends beyond the edge of the recording material. Patent Document 1 also describes a cleaning roller cleaning mode that is executed when the cumulative amount of so-called edge toner adhering to the edge surface (side surface) of the recording material is equal to or greater than a certain value after image formation on the recording material is completed.

[0003] Furthermore, in the patent document 1 below, when a web for collecting toner from the surface of the cleaning roller is further provided, the amount of the web to be wound is determined according to the amount of toner adhering to the edge when the borderless printing mode is executed, thereby enabling the web to be used until its end of its service life. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-129138 Summary of the Invention [Problem to be solved by the invention]

[0005] In the image forming apparatus described above, offset toner adhering to the fixing roller is collected on the circumferential surface of the cleaning roller even in a normal image forming mode other than the borderless printing mode. Therefore, cleaning of the cleaning roller is necessary regardless of the image forming mode. This is true even in an apparatus equipped with a web for collecting toner from the surface of the cleaning roller.

[0006] Therefore, the present invention aims to provide an image forming device and a cleaning method for an image forming device that can sufficiently collect, using a web, any adhesions collected from the fixing roller to the cleaning roller during an image formation job, regardless of the image formation mode, thereby preventing image defects from occurring. [Means for solving the problem]

[0007] To achieve this objective, the present invention provides an image forming apparatus comprising a cleaning roller for collecting adhesions adhering to a fixing section for fixing a toner image to a recording medium, a web supply section for supplying a web to the cleaning roller for collecting adhesions adhering to the cleaning roller, and a control section for controlling the operation of the web supply section, wherein the control section calculates the required feed amount of the web necessary to collect adhesions adhering to the cleaning roller based on image formation job information, and if the required feed amount is greater than the web feed amount possible during execution of image formation of a job related to the job information, supplies the web to the cleaning roller after the image formation is completed. [Effects of the Invention]

[0008] The present invention provides an image forming apparatus and a cleaning method for an image forming apparatus that can sufficiently collect, by means of a web, any deposits collected from the fixing roller onto the cleaning roller during an image forming job, regardless of the image formation mode, thereby preventing image defects from occurring. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a configuration diagram (part 1) showing the main parts of an image forming apparatus according to an embodiment. [Figure 2] FIG. 2 is a second structural diagram showing the main parts of the image forming apparatus according to the embodiment. [Figure 3] FIG. 3 is a block diagram of a main part of the image forming apparatus according to the embodiment. [Figure 4] FIG. 4 is a diagram showing the image area ratio relative to the recording medium. [Figure 5] FIG. 5 is a flowchart (part 1) showing the cleaning method for the image forming apparatus according to the embodiment. [Figure 6] FIG. 6 is a flowchart (part 3) showing the cleaning method for the image forming apparatus according to the embodiment. [Figure 7] FIG. 7 is a graph showing the relationship between the size of the recording medium and the web feed amount during image formation. [Figure 8] FIG. 8 is a graph showing the relationship between the web feed amount and the dirt removal rate for each image area ratio. [Figure 9] FIG. 9 is a diagram (part 1) for explaining a cleaning method for an image forming apparatus according to an embodiment. [Figure 10] FIG. 10 is a diagram (part 2) for explaining a cleaning method for an image forming apparatus according to an embodiment. [Figure 11] FIG. 11 is a diagram illustrating acquisition of the image area ratio in the first modification of the embodiment. [Figure 12] FIG. 12 is a diagram showing settings of the rotation speed of the cleaning roller in the second modification of the embodiment. [Figure 13] FIG. 13 is a configuration diagram showing a main part of an image forming apparatus according to a third modification of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus and a cleaning method for an image forming apparatus to which the present invention is applied will be described in detail below with reference to the accompanying drawings.

[0011] Image forming device 1 and 2 are structural diagrams (part 1) and (part 2) showing the main parts of an image forming apparatus according to an embodiment. The image forming apparatus 1 shown in these FIGS. 1 and 2 is an electrophotographic type that uses toner. This image forming apparatus 1 includes a fixing unit 10, a cleaning roller 21, a web supply unit 30, and a control unit 40, in addition to a medium supply unit and an image forming unit (not shown). These are as follows:

[0012] <Fixing unit 10> The fixing unit 10 is a unit for fixing a toner image transferred onto the recording medium 2 to the recording medium 2. The toner image is an image transferred onto the recording medium 2 in an image forming unit (not shown). The fixing unit 10 includes a fixing roller 11 and a pressure roller 12. The fixing roller 11 is cylindrical and has a heater built into it, and the fixing surface 11a, which is formed by the cylindrical side surface, is heated to a predetermined set temperature by the heater. The fixing roller 11 also has a drive motor and rotates at a predetermined speed [v0] around the cylindrical axis. Meanwhile, the pressure roller 12 is disposed opposite the fixing roller 11 and applies a predetermined pressure to the fixing surface 11a of the fixing roller 11.

[0013] The fixing roller 11 and pressure roller 12 are arranged to sandwich the recording medium 2 conveyed from an image forming unit (not shown here). The recording medium 2 sandwiched between the fixing roller 11 and pressure roller 12 is heated by contact with the fixing surface 11a of the fixing roller 11. The recording medium 2 is also pressurized between the fixing roller 11 and pressure roller 12, and is conveyed in a predetermined conveying direction [FD] as the fixing roller 11 rotates.

[0014] Note that a fixing belt (not shown here) may be wound around the fixing roller 11. In this case, an opposing roller (not shown here) is disposed parallel to the fixing roller 11, and an endless fixing belt is wound between this opposing roller and the fixing roller 11. As a result, the recording medium 2 is sandwiched between the fixing roller 11 and the pressure roller 12 via the fixing belt. In such a configuration, the outer peripheral surface of the fixing belt serves as the fixing surface, but the configuration described below also applies. For this reason, the following description will be given taking as an example a configuration in which the side peripheral surface of the fixing roller 11 serves as the fixing surface 11a.

[0015] <Cleaning Roller 21> The cleaning roller 21 collects offset toner, wax, and other adhering materials that have adhered to the fixing surface 11a of the fixing roller 11. Wax is an external additive contained in the toner, and when it re-adheres from the fixing surface 11a of the fixing roller 11 to the recording medium 2, it causes uneven gloss in the image. For this reason, the cleaning roller 21 collects the wax along with the offset toner from the fixing surface 11a.

[0016] The cleaning roller 21 is disposed parallel to the fixing roller 11, and can be freely brought into contact with (the state shown in FIG. 1) or separated from (the state shown in FIG. 2) the fixing surface 11a of the fixing roller 11 under the control of the control unit 40. The rotation speed [v1] of the cleaning roller 21 can also be freely controlled under the control of the control unit 40.

[0017] For example, when recovering offset toner and wax from the fixing surface 11a of the fixing roller 11, the cleaning roller 21 is in contact with the fixing surface 11a as shown in Fig. 1. This state occurs mainly when the image forming apparatus 1 is in the process of forming an image (printing), and there is a possibility that offset toner and wax may adhere to the fixing surface 11a from the recording medium 2. During this image formation operation, the rotational speed [v1] of the cleaning roller 21 is controlled so that the moving speed of the circumferential surface of the cleaning roller 21 matches the moving speed of the fixing surface 11a of the fixing roller 11.

[0018] On the other hand, when there is no need to collect offset toner and wax from the fixing surface 11a of the fixing roller 11, the cleaning roller 21 is spaced apart from the fixing surface 11a, as shown in Fig. 2. This state occurs mainly when the image forming apparatus 1 is not performing image formation, and there is no possibility that offset toner and wax will adhere to the fixing surface 11a from the recording medium 2. Furthermore, in this state, the rotation speed [v1] of the cleaning roller 21 can be controlled regardless of the movement speed of the fixing surface 11a of the fixing roller 11.

[0019] <Web supply unit 30> The web supply unit 30 collects the offset toner and wax collected by the cleaning roller 21 and cleans the side circumferential surface of the cleaning roller 21. The web supply unit 30 includes a web 31, an unwinding roller 32, a winding roller 33, and a pressure roller 34.

[0020] [Web31] The web 31 is a strip of nonwoven fabric, and collects offset toner and wax adhering to the side circumferential surface of the cleaning roller 21 from the side circumferential surface of the cleaning roller 21 .

[0021] [Unwinding roller 32] The unwinding roller 32 has the web 31 wound therearound and unwinds the web 31 .

[0022] [Winding roller 33] The winding roller 33 is a drive roller that winds up the web 31 wound around the unwinding roller 32. The winding speed of the winding roller 33, i.e., the feed speed [v2] of the web 31 relative to the cleaning roller 21, can be freely controlled by the control unit 40. Note that the moving direction of the web 31 relative to the cleaning roller 21 may be opposite to the direction shown in the figure.

[0023] The pressure roller 34 is disposed parallel to the cleaning roller 21, and presses the web 31, which is unwound from the unwinding roller 32 and wound by the winding roller 33, against the side circumferential surface of the cleaning roller 21. The pressure roller 34 is configured to move in accordance with the contact and separation of the cleaning roller 21 with the fixing roller 11.

[0024] <Control unit 40> The control unit 40 is configured by a computer and controls the operation of the image forming apparatus 1. The computer is hardware used as a so-called computer, and includes a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The computer may also include non-volatile storage and a network interface, as well as an operation unit and a display unit as a user interface. The control unit 40 comprehensively controls the operation of each unit of the image forming apparatus 1 by having the CPU read a predetermined program from the ROM, load it into the RAM, and execute the loaded program.

[0025] Fig. 3 is a block diagram of the main parts of the image forming apparatus 1 according to the embodiment. As shown in Fig. 3, the control unit 40 includes functional units, namely, an image formation control unit 41, a feed amount setting unit 42, and a reference feed amount database 43. These functional units will be described below with reference to Figs. 1 to 3.

[0026] [Image formation control unit 41] The image formation control unit 41 controls the driving of the medium supply unit and the image forming unit (not shown), and further controls the driving of the fixing roller 11, the cleaning roller 21, and the take-up roller 33, thereby controlling the execution of an image formation job by the image forming apparatus 1. The image formation job includes the collection of offset toner and wax from the fixing surface 11a of the fixing roller 11 by the cleaning roller 21. The image formation job also includes the collection of offset toner and wax from the side circumferential surface of the cleaning roller 21 by the web 31.

[0027] In carrying out such an image forming job, the image forming control unit 41 controls the contact / separation of the cleaning roller 21 with respect to the fixing surface 11a of the fixing roller 11, the rotation speed [v1] of the cleaning roller 21, and the feed speed [v2] of the web 31.

[0028] The control of each part by the image formation control part 41 is executed based on information input from an external device or an operation part (not shown) of the image forming apparatus 1, and information from the feed amount setting part 42. Details of the control by the image formation control part 41 will be described later in the image forming method.

[0029] [Feed amount setting section 42] The feed amount setting unit 42 sets the feed amount [F] of the web 31. Here, the feed amount [F] of the web 31 is the length of the web 31 supplied relative to the side circumferential surface of the cleaning roller 21. This feed amount [F] corresponds to the length [L2] of the web 31 taken up by the take-up roller 33 relative to the sliding distance [L1] of the side circumferential surface of the cleaning roller 21. The feed amount setting unit 42 sets the feed amount [F] of the web 31 for cleaning the side circumferential surface of the cleaning roller 21 when performing an image formation job.

[0030] The feed amount setting unit 42 sets the feed amount [F] of the web 31 based on job information about the image formation job acquired from the image formation control unit 41 and a reference feed amount [Fref] stored in a reference feed amount database 43, which will be described next. The job information acquired by the feed amount setting unit 42 from the image formation control unit 41 includes the image area ratio, medium type, toner type, medium size (transport direction), and number of images to be formed.

[0031] Based on this job information, the feed amount setting unit 42 extracts the corresponding reference feed amount [Fref] from the reference feed amounts [Fref] stored in the reference feed amount database 43, which will be described next. The feed amount setting unit 42 also calculates the feed amount [F] of the web 31 required during the job based on the extracted reference feed amount [Fref] and the previous job information. The procedure for setting the feed amount [F] by the feed amount setting unit 42 will be described in detail below in the image forming method.

[0032] [Reference Feed Rate Database 43] The reference feed amount database 43 stores the feed amount [F] of the web 31 for each image area ratio of the toner image on the recording medium 2 as the reference feed amount [Fref]. FIG. 4 is a diagram showing the image area ratio on the recording medium 2. As shown in FIG. 4, the image area ratio is the proportion of the image [p] on the recording medium 2. This image area ratio corresponds to the amount of toner used on the recording medium 2 per specified area. Therefore, the image area ratio also corresponds to the amount of offset toner and wax attached to the fixing surface 11a of the fixing roller 11 and the side surface of the cleaning roller 21, as shown in FIGS. 1 and 2.

[0033] 4 shows a state in which the image [p] is formed in one concentrated area of ​​the recording medium 2, but the image [p] may also be formed in a dispersed manner in various areas of the recording medium 2. As shown in FIG. 4, for example, the reference feed amount database 43 defines an image area rate of 10% or less as small area rate 101, an image area rate of 10% to 50% as medium area rate 102, and an image area rate of 50% or more as large area rate 103, and stores the reference feed amount [Fref] for each of these three levels (or for each of more levels).

[0034] Furthermore, the reference feed amount database 43 holds the reference feed amount [Fref] for each medium type and toner type in the job information.

[0035] The reference feed amount [Fref] is a value obtained when the feed speed [v2] of the web 31 by the take-up roller 33 relative to the rotation speed [v1] of the cleaning roller 21 is in an arbitrary predetermined state. For example, the reference feed amount [Fref] is set as a value during image formation when the rotation speed [v1] of the cleaning roller 21 is determined. The reference feed amount [Fref] is a value obtained through prior experiments that allows offset toner and wax to be recovered from the side circumferential surface of the cleaning roller 21 for each image area ratio, medium type, and toner type.

[0036] <Cleaning method for image forming apparatus> Next, a cleaning method for the image forming apparatus 1 as described above will be described. FIGS. 5 and 6 are flowcharts (part 1) and (part 2) showing the cleaning method for the image forming apparatus according to the embodiment. These flowcharts show procedures carried out by a program stored in the control unit 40 of the image forming apparatus 1. The cleaning method for the image forming apparatus according to the embodiment will be described below in accordance with the flowcharts of FIGS. 5 and 6, with reference to the previous FIGS. 1 to 4 and other necessary figures.

[0037] [Step S101] First, in step S101, image formation control unit 41 acquires job information related to the current job to be performed. This job information is information input from an external device or an operation unit (not shown) of image forming apparatus 1, and includes image area ratio, medium type, toner type, medium size (transport direction), and number of images to be formed.

[0038] [Step S102] In step S102, the image formation control unit 41 determines whether cleaning of the fixing surface 11a of the fixing roller 11 is necessary. At this time, if it is necessary to collect offset toner and wax depending on the type of medium and toner, the image formation control unit 41 determines that cleaning is necessary (YES) and proceeds to step S103. On the other hand, if it is not necessary to collect offset toner and wax depending on the type of medium and toner, it determines that cleaning is not necessary (NO) and proceeds to step S201. Note that the image formation control unit 41 holds information on whether it is necessary to collect offset toner and wax for each type of medium and toner, and makes its determination based on this information.

[0039] [Step S103] In step S103, the image formation control unit 41 controls the drive unit of the cleaning roller 21 to bring the side circumferential surface of the cleaning roller 21 into contact with the fixing surface 11a of the fixing roller 11 as shown in FIG.

[0040] [Step S104] In step S104, the feed amount setting unit 42 calculates the required feed amount [Fr] of the web 31 and the feed amount during image formation [Fp] based on the job information acquired by the image formation control unit 41 in step S101.

[0041] Of these, the required feed amount [Fr] is the feed amount of the web 31 required for the entire job. The feed amount during image formation [Fp] is the feed amount of the web 31 while image formation is being performed. The feed amount during image formation [Fp] is a value included in the required feed amount [Fr]. These are calculated as follows:

[0042] In calculating the required feed amount [Fr], the feed amount setting unit 42 first extracts the reference feed amount [Fref] that matches the medium type, toner type, and image area ratio from the acquired job information, from the reference feed amount database 43. If the image forming apparatus 1 is equipped with a detection device that detects the surface roughness of the recording medium 2, the surface roughness of the recording medium 2 detected by this detection device may be used as the medium type.

[0043] Next, the required feed amount [Fr] is calculated by adding the medium size (conveyance direction) and the number of sheets to be image-formed from the acquired job information to the extracted reference feed amount [Fref].

[0044] In calculating the feed amount during image formation [Fp], the feed amount setting unit 42 calculates the feed amount during image formation [Fp] from, for example, the medium size (transport distance) and the number of sheets to be image-formed, which are included in the acquired job information. At this time, the feed amount setting unit 42 calculates the feed amount during image formation [Fp] by multiplying the web feed amount per sheet of recording medium, which is predetermined for the medium size, by the number of sheets to be image-formed. In other words, the feed amount setting unit 42 calculates the feed amount during image formation [Fp] regardless of the medium type, toner type, and image area ratio, which are included in the job information.

[0045] 7 is a graph showing the relationship between the size of the recording medium and the web feed amount during image formation. The horizontal axis of FIG. 7 represents the medium size (length in the transport direction), and the vertical axis represents the web feed amount [F] during image formation per sheet of recording medium. The feed amount setting unit 42 stores the relationship shown in this graph in advance. The feed amount setting unit 42 calculates the web feed amount during image formation [Fp] by multiplying the web feed amount [F] during image formation per sheet of recording medium extracted based on the medium size (length in the transport direction) acquired as job information by the number of sheets of image formation acquired as job information.

[0046] FIG. 8 is a graph showing the relationship between the web feed amount and the dirt removal rate for each image area ratio. The image area ratios are, for example, three levels: small area ratio 101, medium area ratio 102, and high area ratio 103 (see FIG. 4). The horizontal axis of FIG. 8 represents the web feed amount [F] per sheet of recording medium during image formation. The recording medium size (length in the transport direction) is arbitrary. The vertical axis of FIG. 8 represents the dirt removal rate from the side surface of the cleaning roller 21, i.e., the offset toner and wax recovery rate. As shown in the graph of FIG. 8, regardless of the image area ratio, once the web feed amount [F] increases to a certain extent, the increase in the dirt removal rate reaches a plateau. Therefore, the "web feed amount per sheet of recording medium" used to calculate the feed amount [Fp] during image formation is set within the range [z0] in which the dirt removal rate is expected to increase, regardless of the image area ratio.

[0047] [Step S105] Next, in step S105, the image formation control unit 41 sets the feed amount during image formation [Fp] calculated by the feed amount setting unit 42 in step S104. At this time, the image formation control unit 41 sets the feed speed [v2] of the web 31 taken up by the take-up roller 33 based on the rotation speed [v0] of the fixing roller 11 and the rotation speed [v1] of the cleaning roller 21 during image formation, which are predetermined. This sets the movement distance of the web 31 while forming images for the set number of sheets, i.e., the feed amount during image formation [Fp].

[0048] [Step S106] In step S106, image formation control unit 41 instructs each unit of image forming apparatus 1 to start image formation for the job. As a result, each unit of image forming apparatus 1, including fixing roller 11 and cleaning roller 21, starts image formation on recording medium 2 in accordance with the job information. Also, winding roller 33 starts winding web 31 so as to achieve the feed amount during image formation [Fp] set in step S105.

[0049] [Step S107] In step S107, the feed amount setting unit 42 determines whether or not there is an unexecuted feed amount [Fu]. The unexecuted feed amount [Fu] is the feed amount of the web 31 that could not be executed in the previous job executed immediately before the current job. The feed amount setting unit 42 stores the unexecuted feed amount [Fu] if it occurred in the previous job. If the feed amount setting unit 42 stores the unexecuted feed amount [Fu], the feed amount setting unit 42 determines that there is an unexecuted feed amount [Fu] (YES) and proceeds to step S108. On the other hand, if the feed amount setting unit 42 does not store the unexecuted feed amount [Fu], the feed amount setting unit 42 determines that there is no unexecuted feed amount [Fu] (NO) and proceeds to step S109.

[0050] [Step S108] In step S108, the feed amount setting unit 42 adds the unimplemented feed amount "Fu" to the required web feed amount [Fr] calculated in step S104 to obtain a new required feed amount [Fr], and then proceeds to step S109.

[0051] [Step S109] In step S109, the feed amount setting unit 42 determines whether the value obtained by subtracting the feed amount during image formation [Fp] calculated in step S104 from the required feed amount [Fr] is equal to or greater than zero. If it determines that the value is equal to or greater than zero (YES), the process proceeds to step S110.

[0052] On the other hand, if it is determined that the value is not equal to or greater than zero (NO), the process is terminated. In this case, the required feed amount [Fr] is equal to or less than the feed amount during image formation [Fp], and feeding of the web 31 by the required feed amount [Fr] is completed during image formation of the current job, so the process may be terminated. However, the end of the process here refers to the end of cleaning of the cleaning roller 21 during the job. The job is terminated after image formation for the number of sheets acquired in step S101 is completed.

[0053] [Step S110] In step S110, the feed amount setting unit 42 calculates the insufficient feed amount [Fs] by subtracting the feed amount during image formation [Fp] calculated in step S104 from the required feed amount [Fr].

[0054] [Step S111] In step S111, the feed amount setting unit 42 determines whether or not a next job is reserved following the current job being executed, based on information from the image formation control unit 41. If it determines that a next job is reserved (YES), the process proceeds to step S120. On the other hand, if it determines that a next job is not reserved (NO), the process proceeds to step S112.

[0055] [Step S112] In step S112, the image formation control unit 41 cleans the side circumferential surface of the cleaning roller 21 by feeding the web 31 by the feeding shortage amount [Fs] after the image formation of the current job currently being performed is completed.

[0056] At this time, when image formation for the job is completed, the image formation control unit 41 separates the side circumferential surface of the cleaning roller 21 from the fixing surface 11a of the fixing roller 11, as shown in Fig. 2. With the side circumferential surface of the cleaning roller 21 separated from the fixing surface 11a of the fixing roller 11, the image formation control unit 41 cleans the side circumferential surface of the cleaning roller 21. When cleaning is completed, the entire processing of the job is completed.

[0057] [Step S120] Step S120 is a step to which the process proceeds if the next job is reserved (YES) in step S111. In step S120, the feed amount setting unit 42 determines whether the inter-job possible feed amount [Fa] is greater than the insufficient feed amount [Fs]. Here, the inter-job period refers to the job end period required from the end of image formation in the current job being performed until the start of the next job, and is included in the period of the current job. The inter-job possible feed amount [Fa] is the amount of web 31 that can be fed during this job end period and depends on the feed speed [v2] of the web 31. If the feed amount setting unit 42 determines that the inter-job possible feed amount [Fa] is greater than the insufficient feed amount [Fs] (YES), the process proceeds to step S121. If the feed amount setting unit 42 determines that the inter-job possible feed amount [Fa] is not greater (NO), the process proceeds to step S122.

[0058] [Step S121] In step S121, after completing image formation for the current job currently being performed, the image formation control unit 41 advances the web 31 by the shortfall [Fs] to clean the side circumferential surface of the cleaning roller 21. This step S121 is the same as the previous step S112, and after the cleaning is completed, the entire processing of the job is completed.

[0059] [Step S122] On the other hand, in step S122, the feed amount setting unit 42 stores the value obtained by subtracting the inter-job possible feed amount [Fa] from the insufficient feed amount [Fs] as the unexecuted feed amount [Fu].

[0060] 9 and 10 are diagrams (part 1) and (part 2) illustrating a cleaning method for an image forming apparatus according to an embodiment. As shown in these diagrams, assuming that the current job being performed is the nth job, the feed amount obtained by subtracting the feed amount during image formation [Fp] from the required feed amount [Fr] of the web 31 during the nth job is the feed amount obtained by subtracting the feed amount during image formation [Fp]. The unimplemented feed amount [Fu] is the feed amount obtained by subtracting the possible inter-job feed amount [Fa] that can be implemented during the job end period from the feed amount during image formation [Fp] in the nth job to the start of the next n+1th job from the feed amount by the feed amount by the feed shortage [Fs]. The unimplemented feed amount [Fu] calculated here is the unimplemented feed amount [Fu] for steps S107, S108, and S203 in the n+1th job to be performed next.

[0061] Therefore, for example, in step S108 of processing the next (n+1)th job, the required feed amount [Fr] of the web 31 calculated in step S104 is added to the unimplemented feed amount [Fu] occurring in the nth job to obtain the new required feed amount [Fr]. Therefore, the unimplemented feed amount [Fu] occurring in the currently executing nth job will be implemented in the next (n+1)th job.

[0062] In addition, if the possible inter-job feed amount [Fa] is greater than the missing feed amount [Fs] (if the answer is NO in step S120), no new unexecuted feed amount [Fu] will occur, as in the n+1th job in Figure 10.

[0063] [Step S123] In step S123, after completing image formation for the current job currently being performed, the image formation control unit 41 feeds the web 31 by the possible inter-job feed amount [Fa] to clean the side circumferential surface of the cleaning roller 21. This step S123 is a step that differs from the previous step S112 only in the feed amount of the web 31, and the entire processing of the job ends when cleaning is completed.

[0064] [Step S201] Furthermore, step S201 is a step to which the process proceeds after determining in the previous step S102 that cleaning of the fixing surface 11a is not necessary (NO). In this step S201, the image formation control unit 41 separates the cleaning roller 21 from the fixing surface 11a, as shown in FIG.

[0065] [Step S202] In step S202, image formation control unit 41 instructs each unit of image forming apparatus 1 to start image formation for the job. As a result, each unit of image forming apparatus 1, including fixing roller 11 and cleaning roller 21, starts image formation on recording medium 2 in accordance with the job information.

[0066] [Step S203] In step S203, the feed amount setting unit 42 determines whether there is an unexecuted feed amount [Fu]. This determination is made in the same procedure as in step S107, and if it is determined that there is an unexecuted feed amount [Fu] (YES), the process proceeds to step S204. On the other hand, if it is determined that there is no unexecuted feed amount [Fu] (NO), the process ends. However, the end of the process here refers to the end of cleaning of the cleaning roller 21 during the job. The job ends after image formation for the number of sheets of image formation acquired in step S101 has been completed.

[0067] [Step S204] In step S204, the image formation control unit 41 cleans the side circumferential surface of the cleaning roller 21 by the uncompleted feed amount [Fu], and then ends the process. Note that the end of the process here refers to the end of the cleaning process of the cleaning roller 21 during the job. The job ends after image formation for the number of sheets of image formation acquired in step S101 has been completed.

[0068] Effect of the embodiment According to the embodiment described above, the required feed amount [Fr] of the web 31 is calculated based on the image area ratio of the job, and if the web 31 cannot be fed the required feed amount [Fr] during image formation, the web 31 is fed by the insufficient feed amount [Fs] after image formation is completed. This allows the web 31 to sufficiently collect offset toner and wax on the side circumferential surface of the cleaning roller 21, regardless of the image formation mode.

[0069] Furthermore, if an uncompleted feed amount [Fu] occurs between the end of image formation and the start of the next job, the uncompleted feed amount [Fu] is added to the required feed amount [Fr] for the next job, thereby preventing the accumulation of uncollected offset toner and wax on the side circumferential surface of the cleaning roller 21.

[0070] As a result of the above, it is possible to prevent the offset toner and wax from re-adhering from the cleaning roller 21 to the fixing surface 11a, and to form images without any defects.

[0071] <<Variation 1>> As a first modification of the embodiment described above, another example of the image area ratio acquired by the feed amount setting unit 42 in step 101 will be described. FIG. 11 is a diagram illustrating acquisition of the image area ratio in the first modification of the embodiment. As shown in FIG. 11, the feed amount setting unit 42 acquires, as one piece of job information, the image area ratio of each of the regions [A1] to [A6] obtained by dividing the recording medium 2 in the conveyance width direction [CD]. Note that the number of divisions of the recording medium 2 in the conveyance width direction [CD] is not limited to six divisions of the regions [A1] to [A6], and may be a number of divisions according to the characteristics of the image to be formed on the recording medium 2.

[0072] In this case, when calculating the required web feed amount [Fr] in step S104, the reference feed amount [Fref] associated with the highest image area ratio among the image area ratios of each area [A1] to [A6] is extracted from the reference feed amount database 43.

[0073] According to this variant example 1, even if there is a large difference in image area ratio in the conveying width direction [CD], it is possible to clean the side surface of the cleaning roller 21 without leaving any offset toner or wax remaining partially recovered in the conveying width direction [CD].

[0074] <<Variation 2>> As a second modification of the embodiment described above, a configuration will be described in which the rotation speed [v1] of the cleaning roller 21 is changed when cleaning the side circumferential surface of the cleaning roller. This configuration is applied to steps S112, S121, S123, and step 204. That is, this configuration is applied when cleaning the side circumferential surface of the cleaning roller 21 while the cleaning roller 21 is spaced apart from the fixing surface 11a, as shown in FIG.

[0075] In this case, the rotation speed [v1] of the cleaning roller 21 is not affected by the rotation speed of the fixing roller 11. Therefore, the rotation speed [v1] of the cleaning roller 21 can be set to a value that takes into consideration the cleaning performance of the side circumferential surface of the cleaning roller 21.

[0076] Therefore, when the insufficient feed amount [Fs] of the web supplied to the cleaning roller 21 after image formation is completed is greater than a predetermined feed amount, the feed amount setting unit 42 of the control unit 40 changes the rotation speed of the cleaning roller 21. This is applied when, based on the job information, it is expected that the amount of offset toner and wax adhering to the side circumferential surface of the cleaning roller 21 will be greater than a predetermined amount.

[0077] Here, the slower the rotation speed [v1] of the cleaning roller 21, the longer the contact time of the side circumferential surface of the cleaning roller 21 with the web 31. This may improve the recovery rate of the offset toner and wax by the web 31. Therefore, as shown in FIG. 2, when cleaning the side circumferential surface of the cleaning roller 21 while the cleaning roller 21 is spaced from the fixing surface 11a, the rotation speed [v1] of the cleaning roller 21 is set to be slower than that during image formation.

[0078] Fig. 12 is a diagram showing the setting of the rotation speed of the cleaning roller in Modification 2 of the embodiment. In this case, the control unit 40 (see Figs. 1 to 3) has a database relating to the rotation speed of the cleaning roller, which associates the rotation speed of the cleaning roller with the image area ratio and the number of images formed on a sheet as shown in Fig. 12. In this database, the rotation speed of the cleaning roller 21 is set lower as the number of images formed on a sheet increases and as the image area ratio increases. In other words, the rotation speed of the cleaning roller 21 is set lower as the amount of toner adhering to the circumferential surface of the cleaning roller 21 in a job increases.

[0079] Furthermore, the image forming control unit 41 extracts the rotation speed of the cleaning roller 21 from this database based on the image area ratio and the number of images formed in the job information. Then, when cleaning the side circumferential surface of the cleaning roller 21 in the state shown in Fig. 2 in steps S112, S204, etc., the image forming control unit 41 adjusts the rotation speed of the cleaning roller 21 to the extracted rotation speed. Note that, although the rotation speeds of the cleaning roller 21 are shown as low, medium, and high in Fig. 12, it is assumed that each of these speeds has been set to an appropriate value through experiments in advance.

[0080] Furthermore, as described above, when the rotation speed [v1] of the cleaning roller 21 is changed to a speed slower than that during image formation after image formation is completed, the feed speed [V2] of the web 31 is also changed. Here, as described in the previous embodiment with reference to FIG. 8, the dirt removal rate from the side surface of the cleaning roller 21 by the web 31 reaches a plateau when the web feed amount [F] increases to a certain extent. Therefore, as the rotation speed [v1] of the cleaning roller 21 is slowed, the feed speed [v3] of the web 31 is also slowed to fall within the range [z0] where an increase in the dirt removal rate is expected.

[0081] According to Modification 2, by adjusting the rotation speed [v1] of the cleaning roller 21 after image formation is completed, it is possible to improve the recovery rate of offset toner and wax from the side circumferential surface of the cleaning roller 21 by the web 31. In addition, by slowing down the feed speed of the web 31, it is also possible to reduce the feed amount of the web 31.

[0082] In this second modification, the recovery rate of offset toner and wax is improved as the contact time of the web 31 with the circumferential side surface of the cleaning roller 21 increases. However, depending on the type of recording medium 2 and the type of toner, even if the contact time is shortened, the recovery rate improves as the difference between the rotational speed [V1] of the cleaning roller 21 and the feed speed [V2] of the web increases. In this case, as shown in FIG. 2, when cleaning the circumferential side surface of the cleaning roller 21 while the cleaning roller 21 is spaced from the fixing surface 11a, the rotational speed [v1] of the cleaning roller 21 can be set to be faster than during image formation. In this case, the feed speed [v2] of the web 31 is also increased so as to fall within the range [z0] where an increase in the dirt removal rate is expected.

[0083] Furthermore, as described above, when the rotation speed [v1] of the cleaning roller 21 and the feed speed [v2] of the web 31 are changed during image formation and after image formation is completed, the feed shortage [Fs] after image formation is completed is also changed. In this case, the feed amount setting unit 42 (FIG. 3) may correct the feed shortage [Fs] in accordance with the change in the speed in step S110 shown in FIG. 5.

[0084] <<Variation 3>> Fig. 13 is a structural diagram showing the main parts of an image forming apparatus 1' in Modification 3 of the embodiment. The image forming apparatus 1' shown in Fig. 13 differs from the image forming apparatus 1 shown in Fig. 1 and Fig. 2 in that a detection device 60 is provided for detecting the amount of offset toner and wax adhering to the side circumferential surface of the cleaning roller 21.

[0085] This detection device 60 is, for example, a reflective optical sensor, which measures the adhesion state of offset toner and wax on the side circumferential surface of the cleaning roller 21 at predetermined intervals and sends the measurement results to the control unit 40. The image formation control unit 41 controls the rotation speed of the cleaning roller 21 based on the measurement results of the detection device 60. This control is applied to steps S112, S121, S123 and step 204. That is, as shown in FIG. 2, this control is applied when cleaning the side circumferential surface of the cleaning roller 21 while the cleaning roller 21 is spaced from the fixing surface 11a.

[0086] In this case, the control unit 40 has a determination unit that determines the amount of offset toner and wax adhering to the side circumferential surface of the cleaning roller 21 based on the measurement results of the detection device 60.

[0087] When the determining unit determines that the amount of adhesion is greater than a predetermined amount, the image formation control unit 41 cleans the side circumferential surface of the cleaning roller 21 by slowing the rotation speed [v1] of the cleaning roller 21 to a value lower than that during image formation, in the same manner as in Modification 2. In this case, the feed speed [V2] of the web 31 is also changed, in the same manner as in Modification 2. This improves the recovery rate of offset toner and wax.

[0088] On the other hand, if the determining unit determines that the amount of toner adhesion is less than the predetermined amount, the image formation control unit 41 may increase the rotation speed [v1] of the cleaning roller 21 after the image formation is completed compared to during the image formation, thereby shortening the cleaning time for the side circumferential surface of the cleaning roller 21.

[0089] The judgment value of the adhesion amount and the adjustment amount of the rotation speed [v1] of the cleaning roller 21 may be adjusted in stages.

[0090] According to Modification 3, it is possible to adjust the rotation speed [v1] of the cleaning roller 21 depending on the degree of adhesion of offset toner and wax to the side peripheral surface, thereby improving the recovery rate of offset toner and wax and shortening the cleaning time of the side peripheral surface of the cleaning roller 21.

[0091] Also, in this variant 3, as in variant 2, depending on the type of medium and toner of the recording medium 2, increasing the rotation speed [v1] of the cleaning roller 21 may improve the recovery rate of offset toner and wax.

[0092] Furthermore, as in Modification 2, when the rotation speed [v1] of the cleaning roller 21 and the feed speed [v2] of the web 31 are changed between during image formation and after image formation is completed, the feed shortage [Fs] after image formation is completed is also changed. In this case, the feed amount setting unit 42 (FIG. 3) may correct the feed shortage [Fs] in accordance with the change in the speed in step S110 shown in FIG. 5.

[0093] <<Variation 4>> As a fourth modification of the embodiment, a configuration will be exemplified in which the image forming operation is interrupted during image formation of a job, and cleaning of the side circumferential surface of the cleaning roller 21 is performed. In this case, the control unit 40 has a determination unit that determines the amount of offset toner and wax adhering to the side circumferential surface of the cleaning roller 21, for example, based on the measurement results of the detection device 60 shown in the third modification. Note that the determination of the amount of offset toner and wax adhering by the determination unit may be based on job information.

[0094] If the determination unit determines that the amount of adhesion is greater than a predetermined amount, the image formation control unit 41 suspends the image formation operation during the image formation of the job. Then, as shown in FIG. 2, the cleaning roller 21 is separated from the fixing surface 11a and the side circumferential surface of the cleaning roller 21 is cleaned. In this case, the rotation speed [v1] of the cleaning roller 21 may be slower than that during image formation. Note that in this case, the feed amount of the web 31 during cleaning performed after suspending the image formation operation is included in the feed amount during image formation [Fp]. Steps 107 and subsequent steps shown in FIGS. 5 and 6 may be performed in the same manner as described in the embodiment.

[0095] According to Modification 4, when performing continuous image formation on a plurality of recording media 2, if a large amount of offset toner and wax adheres to the side circumferential surface of the cleaning roller 21, the image formation can be interrupted and the toner and wax can be collected. Therefore, even if a large amount of offset toner and wax adheres to the cleaning roller 21 during image formation on a plurality of recording media 2, image formation without any problems is possible. [Explanation of symbols]

[0096] 1, 1'...image forming apparatus 2...Recording media 11...Fuser roller 11a...Fixed surface 12...Pressure roller 21...Cleaning roller 30...Web supply section 31…Web 32...Unwinding roller 33...winding roller 34...Pressure roller 40...Control unit 41...Image formation control unit 42...Feed amount setting section 43...Reference feed amount database 60...Detection device [F]...Feed rate [Fa]…Feed amount between jobs [Fp]...Feed amount during image formation [Fr]...Required feed amount [Fref]...Reference feed amount [Fs]…Feed shortage [Fu]...Unimplemented feed amount [V1]...Rotational speed (cleaning roller) [v2]...Feed speed (web)

Claims

1. a cleaning roller for collecting deposits adhering to a fixing unit for fixing a toner image on a recording medium; a web supply unit that supplies a web to the cleaning roller for collecting deposits adhered to the cleaning roller; a control unit that controls an operation of the web supply unit, The control unit A required feed amount of the web required to collect the deposits adhering to the cleaning roller is calculated based on job information of the image formation, and when the required feed amount is greater than the possible feed amount of the web during the execution of the image formation of the job related to the job information, the web is supplied to the cleaning roller after the image formation is completed. Image forming device.

2. The control unit When the necessary feed amount of the web cannot be supplied to the cleaning roller and an incomplete feed amount occurs during the time until image formation of a job reserved next to the job is started, the web for the incomplete feed amount is supplied to the cleaning roller at a timing separate from the job. The image forming apparatus according to claim 1 .

3. The other timing is during the next reserved job after the job. The image forming apparatus according to claim 2 .

4. The web supply unit sets the feed speed of the web relative to the cleaning roller separately during the image formation and after the image formation is completed. The image forming apparatus according to claim 1 .

5. The job information includes an image area ratio of the toner image to the recording medium, a medium type of the recording medium, a toner type constituting the toner image, a medium size of the recording medium, and a number of sheets of image formation. The image forming apparatus according to claim 1 .

6. the fixing unit has a fixing roller for heating the recording medium, and conveys the recording medium in a rotation direction of the fixing roller; The control unit calculates a required feed amount of the web based on an image area ratio of each divided region obtained by dividing the recording medium in a conveyance width direction perpendicular to a conveyance direction of the recording medium by the fixing unit. The image forming apparatus according to claim 5 .

7. a detection device for detecting the surface roughness of the recording medium; The control unit determines the medium type in the job information based on the surface roughness detected by the detection device. The image forming apparatus according to claim 5 .

8. The cleaning roller is the fixing unit rotates at a predetermined rotation speed while in contact with the fixing unit during the image formation; After the image formation is completed, the rotation speed is changed in a state where the image forming apparatus is separated from the fixing unit. The image forming apparatus according to claim 1 .

9. The web supply unit changes the feed speed of the web relative to the cleaning roller in response to a change in the rotation speed of the cleaning roller. The image forming apparatus according to claim 8 .

10. The control unit changes the rotation speed of the cleaning roller when a feed amount of the web supplied to the cleaning roller after the image formation is completed is greater than a predetermined feed amount. The image forming apparatus according to claim 9 .

11. The cleaning roller changes its rotation speed based on the amount of deposits on the cleaning roller. The image forming apparatus according to claim 9 .

12. a detection device for detecting the amount of adhesion of matter adhering to the cleaning roller; The control unit changes the rotation speed of the cleaning roller when the amount of adhesion detected by the detection device is greater than a predetermined feed amount. The image forming apparatus according to claim 9 .

13. When the control unit determines, based on the job information, that the amount of the deposit on the cleaning roller is greater than a predetermined amount, the control unit interrupts image formation for the job, and supplies the web to the cleaning roller in a state in which the cleaning roller is separated from the fixing unit. The image forming apparatus according to claim 1 .

14. A cleaning method for an image forming apparatus including a cleaning roller for collecting deposits adhered to a fixing unit for fixing a toner image on a recording medium, and a web supply unit for supplying a web for collecting deposits adhered to the cleaning roller to the cleaning roller, the method comprising: A control unit that controls the operation of the web supply unit calculates a necessary feed amount of the web required to collect the deposits adhered to the cleaning roller based on job information of the image formation, and when the necessary feed amount is greater than a possible feed amount of the web during execution of the image formation of the job related to the job information, supplies the web to the cleaning roller after the image formation is completed. A cleaning method for an image forming apparatus.

Images