JP2016180926A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that can select an optimal combination on the basis of a plurality of factors of generation of paper powder and remove paper powder adhered to a fixing roller, and an image forming apparatus.SOLUTION: A fixing device 6 comprises: cleaning means W that cleans a surface of a fixing member; pressing means 61g that presses the cleaning means W against a surface of a fixing member 61a; take-up means 61h that takes up to recover the cleaning means W; a take-up amount adjustment part 63 that adjusts the amount of take-up of the cleaning means W performed by the take-up means 61h; a pressing force adjustment part 64 that adjusts a pressing force of the pressing means 61g pressing the cleaning means W; and a control part 7 that controls the take-up amount adjustment part 63 and the pressing force adjustment part 64 on the basis of two or more conditions from among a plurality of conditions related to image formation.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fixing device and an image forming apparatus.

  Conventionally, in an electrophotographic image forming apparatus, a toner image formed on an image carrier (for example, a photosensitive drum) is transferred to a recording medium such as paper, and the toner image transferred to the recording medium is fixed. A fixing device is known. As this fixing device, for example, there is a configuration in which a recording medium onto which a toner image is transferred is conveyed while being nipped at a nip portion formed by pressing a heated fixing roller with a pressure roller.

  In such a fixing device, the paper dust generated by the fixing process and adhering to the fixing roller is cleaned and removed by the cleaning web, but the paper dust that has not been completely removed separates the recording medium from the fixing roller. The paper dust collected in this way may contaminate the recording medium.

  Further, when fixing a paper having a narrow paper width, paper dust at a paper edge in a direction orthogonal to the conveyance direction of the paper adheres to the fixing roller, and a trace of the paper edge is generated on the surface of the fixing roller. When fixing processing is performed on a wide sheet with the fixing roller in such a state, the trace of the edge of the sheet is transferred to the wide sheet, and the wide sheet becomes dirty. Sometimes it ends up.

  For this reason, a fixing device is disclosed that efficiently cleans and removes paper dust from a fixing roller by increasing the feed amount of the cleaning web in accordance with the print image density (see Patent Document 1). Further, an image forming apparatus is disclosed that removes paper dust attached to the fixing roller by using any one of the feeding amount of the cleaning web, the winding interval, the pressing force, or a combination thereof according to the thickness of the paper. (See Patent Document 2).

JP 2013-044861 A Japanese Patent Laid-Open No. 04-243288

  However, in the fixing device described in Patent Document 1, since the cleaning web feed amount is only increased in accordance with the print image density, the cleaning web consumption is increased, and the cleaning web replacement frequency is increased. There was a problem that it increased and led to a decrease in productivity.

  On the other hand, in the image forming apparatus described in Patent Document 2, depending on the thickness of the paper, the paper adhering to the fixing roller by the cleaning web feed amount, the winding interval, the pressing force, or a combination thereof. Although the dust is removed, the feeding amount of the cleaning web is switched in two stages (increase / decrease) considering only the paper thickness, and only the paper thickness is considered. Since the factor which generate | occur | produces powder is not considered, there exists a possibility that an optimal combination cannot be selected.

  For example, when paper dust adhering to the fixing roller cannot be sufficiently removed due to selection of an inappropriate combination, the pressing force of the cleaning web is too strong, the member that presses the cleaning web may be deformed, There has been a problem that a side effect of causing scratches on the surface of the fixing roller may occur due to insufficient removal of paper dust.

  An object of the present invention is to provide a fixing device and an image forming apparatus capable of selecting an optimal combination based on a plurality of factors that generate paper dust and removing paper dust attached to a fixing member.

In order to achieve the above object, a fixing device according to claim 1 is provided.
In a fixing device for fixing a toner image on a sheet by passing the sheet on which the toner image is formed through a nip formed by heating and pressing at least one of a pair of fixing members.
Cleaning means for cleaning the surface of the fixing member;
Pressing means for pressing the cleaning means against the surface of the fixing member;
A winding means for winding and collecting the cleaning means;
A winding amount adjusting unit for adjusting a winding amount of the cleaning unit by the winding unit;
A pressing force adjusting unit that adjusts the pressing force of the cleaning unit by the pressing unit;
A control unit that controls the winding amount adjustment unit and the pressing force adjustment unit based on two or more conditions among a plurality of conditions related to image formation;
It is characterized by having.

According to a second aspect of the present invention, in the fixing device according to the first aspect,
When the control unit determines that paper dust increases due to the two or more conditions, the winding amount adjustment unit and the pressure adjustment so as to increase at least one of the pressing force and the winding amount. It is characterized by controlling the part.

According to a third aspect of the present invention, in the fixing device according to the first or second aspect,
The conditions are orthogonal to the distance from the paper feed tray to which the paper is fed to the nip or the vicinity of the nip, the orientation of the paper in the paper making direction with respect to the transport direction, the image forming speed, or the paper transport direction. It is characterized by the width of the paper in the direction of the paper.

According to a fourth aspect of the present invention, in the fixing device according to the third aspect,
The control unit is configured to determine the winding amount set in advance in a plurality of stages based on the length of the distance, the direction of the paper making direction, the image forming speed, and the difference between the paper width and the paper width at the time of the previous fixing process. Each of the pressing forces set in a plurality of stages is selected and combined for control.

According to a fifth aspect of the present invention, in the fixing device according to the fourth aspect,
The control unit is configured such that the distance is within a predetermined distance, the paper making direction is perpendicular to the transport direction, the image forming speed is equal to or lower than a predetermined speed, and the difference between the paper width and the paper width at the previous fixing process is positive. When it is determined that the value is a value, control is performed by selecting a minimum value among a plurality of values as the winding amount and the pressing force.

According to a sixth aspect of the present invention, in the fixing device according to the fourth aspect,
The control unit is configured such that the distance is equal to or greater than a predetermined distance, the paper making direction is parallel to the transport direction, the image forming speed is faster than a predetermined speed, and the difference between the paper width and the paper width at the previous fixing process is negative. When it is determined that the maximum value is selected, a maximum value among a plurality of levels is selected and controlled as the winding amount and the pressing force.

The invention according to claim 7 is the fixing device according to any one of claims 4 to 6,
The control unit is characterized in that after the fixing process is completed, the winding amount and the pressing force are returned to a minimum value among a plurality of levels.

An image forming apparatus according to an eighth aspect of the present invention includes:
An image forming unit that forms a toner image on paper;
The fixing device according to any one of claims 1 to 7, wherein the toner image is fixed to the paper through the paper on which the toner image is formed;
It is characterized by having.

  According to the present invention, it is possible to select an optimal combination based on a plurality of factors that generate paper dust and to remove the paper dust attached to the fixing member.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment to which the present invention is applied. FIG. 2 is a block diagram illustrating a functional configuration of the image forming apparatus in FIG. 1. FIG. 2 is an enlarged schematic view of a fixing device. It is a table | surface which shows an example of the winding amount and the pressing force which were preset in three steps. It is a flowchart explaining the control operation of a control part. It is a table | surface which shows the contrast of the result of an Example and a comparative example.

(Embodiment)
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.
FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 100 according to an embodiment to which the present invention is applied. FIG. 2 is a block diagram illustrating a functional configuration of the image forming apparatus 100.

As shown in FIGS. 1 and 2, the image forming apparatus 100 according to the present exemplary embodiment includes image data acquired by reading a color image formed on a document, or an external information device (for example, a personal computer) via a network. An image is formed by superimposing colors on a sheet (recording medium) M based on image data input from a computer.
In addition, the image forming apparatus 100 travels the photosensitive drums 43Y, 43M, 43C, and 43K corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K) on the intermediate transfer belt 47a. This is a tandem type image forming apparatus that is arranged in series in the direction and sequentially transfers toner images of respective colors to a transfer medium in one procedure.

  Specifically, the image forming apparatus 100 of the present embodiment includes an image reading unit 1, an operation display unit 2, an image processing unit 3, an image forming unit 4, a transport unit 5, a fixing device 6, and a control. The unit 7 is provided.

  The image reading unit 1 includes an automatic document feeder 11 called an ADF (Auto Document Feeder), a document image scanning device (scanner) 12, and the like.

  The automatic document feeder 11 conveys the document placed on the document tray by the conveyance mechanism and sends it out to the document image scanning device 12. The automatic document feeder 11 can continuously read images (including both sides) of a large number of documents placed on the document tray at once.

The document image scanning device 12 optically scans a document conveyed on the contact glass from the automatic document feeder 11 or a document placed on the contact glass, and reflects light from the document to a CCD (Charge Coupled Device). ) An image is formed on the light receiving surface of the sensor 12a, and an original image is read. The image (analog image signal) read by the image reading unit 1 is subjected to predetermined image processing in the image processing unit 3.
Here, the image means not only image data such as graphics and photographs but also text data such as characters and symbols.

The operation display unit 2 includes a liquid crystal display (LCD) with a touch panel and the like, and functions as the display unit 21 and the operation unit 22.
The display unit 21 displays various operation screens, image status display, operation status of each function, and the like in accordance with a display control signal input from the control unit 7.
The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs an operation signal to the control unit 7.

The image processing unit 3 includes a circuit that performs analog-digital (A / D) conversion processing, a circuit that performs digital image processing, and the like.
The image processing unit 3 generates digital image data (RGB signals) by subjecting the analog image signal from the image reading unit 1 to A / D conversion processing. In addition, the image processing unit 3 performs color conversion processing, correction processing (such as shading correction) according to initial settings or user settings, compression processing, and the like on the digital image data. The image forming unit 4 is controlled based on the digital image data (YMCK signal) subjected to these processes.

  The image forming unit 4 includes exposure devices 41Y, 41M, 41C, and 41K, developing devices 42Y, 42M, 42C, and 42K, and a photosensitive drum 43Y, which are provided corresponding to different color components Y, M, C, and K. 43M, 43C, 43K, charging devices 44Y, 44M, 44C, 44K, lubricant application removing units 45Y, 45M, 45C, 45K, primary transfer rollers 46Y, 46M, 46C, 46K and intermediate transfer unit 47, etc. It is prepared for.

In the Y component unit of the image forming unit 4, the charging device 44Y charges the photosensitive drum 43Y. The exposure device 41Y is composed of, for example, a semiconductor laser, and irradiates the photosensitive drum 43Y with laser light corresponding to the Y component. As a result, an electrostatic latent image of the Y component is formed on the surface of the photosensitive drum 43Y. The developing device 42Y contains a Y-component developer (for example, a two-component developer composed of a toner having a small particle diameter and a magnetic material), and causes the Y-component toner to adhere to the surface of the photosensitive drum 43Y. Thus, the electrostatic latent image is developed (formation of a toner image).
Similarly, in the units for M component, C component, and K component, each color toner image is formed on the surface of the corresponding photosensitive drum 43M, 43C, 43K.

  The lubricant applying / removing portions 45Y, 45M, 45C, and 45K apply lubricant to the surfaces of the photosensitive drums 43Y, 43M, 43C, and 43K, and excessively adhere to the surfaces of the photosensitive drums 43Y, 43M, 43C, and 43K. Remove the lubricant and foreign matter.

The intermediate transfer unit 47 includes a plurality of support rollers 47b and an endless intermediate transfer belt 47a serving as a transfer target, which is stretched.
When the intermediate transfer belt 47a is brought into pressure contact with the photosensitive drums 43Y, 43M, 43C, and 43K by the primary transfer rollers 46Y, 46M, 46C, and 46K, the toner images of the respective colors are sequentially superimposed and primarily transferred onto the intermediate transfer belt 47a. . Then, the intermediate transfer belt 47a subjected to the primary transfer is pressed against the paper M by the secondary transfer roller 48, whereby the toner image is secondarily transferred to the paper M.
The toner remaining on the intermediate transfer belt 47a after the secondary transfer is removed by a blade or the like of the cleaning device 49.

The transport unit 5 includes a paper feeding device 51, a transport mechanism 52, a paper discharge device 53, and the like.
The paper feeding device 51 includes three paper feeding tray units 51a to 51c. In these paper feed tray units 51a to 51c, standard paper and special paper identified based on the basis weight, size, and the like of the paper M are stored for each preset type. The sheets M accommodated in the sheet feeding tray units 51a to 51c are sent out one by one from the uppermost part, and are conveyed to the image forming unit 4 by a conveying mechanism 52 including a plurality of conveying rollers such as a registration roller 52a. At this time, the registration unit in which the registration roller 52a is disposed corrects the inclination of the fed paper M and adjusts the conveyance timing.

  Then, in the image forming unit 4, the toner image on the intermediate transfer belt 47 a is secondarily transferred onto the image forming surface of the paper M at once, and a fixing process is performed in the fixing device 6. The sheet M on which the image has been formed is discharged to a discharge tray 53b outside the apparatus by a discharge device 53 having a discharge roller 53a.

The fixing device 6 performs a fixing process for fixing the toner image transferred to the paper M.
Hereinafter, the fixing device 6 will be described in detail with reference to FIGS.

  FIG. 3 is an enlarged schematic view of the fixing device 6. As shown in FIG. 2, the fixing device 6 includes a fixing unit 61, a storage unit 62, a winding amount adjustment unit 63, a pressing force adjustment unit 64, a distance acquisition unit 65, a paper width acquisition unit 66, and the like. It is configured.

  The fixing unit 61 includes a pair of fixing members, a fixing roller 61a and a pressure roller 61b, and an external heating roller 61c that contacts the pressure roller 61b and heats the pressure roller 61b. A fixing heater 61d is provided inside the fixing roller 61a, and an external heating heater 61e is provided inside the external heating roller 61c. Further, the fixing roller 61a and the pressure roller 61b constitute a nip portion N that sandwiches and conveys the paper M.

The fixing roller 61a is disposed on the image forming surface side of the paper M, and the fixing roller 61a rotates in accordance with driving of a driving unit such as a motor (not shown).
The fixing roller 61a has a configuration in which, for example, an elastic layer made of silicone rubber or the like is formed on the outer peripheral surface of a cylindrical metal core made of iron or the like, and a halogen heater or the like is built in as the fixing heater 61d. At the same time, the sheet M is contacted with the image forming surface of the sheet M on which the toner image is transferred, and the sheet M is heated at a predetermined fixing temperature. That is, the fixing roller 61a contacts the image forming surface of the paper M while rotating and heats the paper M.
The predetermined fixing temperature is a temperature at which the amount of heat necessary to melt the toner when the paper M passes through the nip portion N, and varies depending on the paper type of the paper M on which an image is formed.

  The pressure roller 61b is disposed to face the fixing roller 61a, and is pressed against the fixing roller 61a with a predetermined pressing force. That is, the pressure roller 61b functions as a pressure unit that sandwiches and pressurizes the paper M together with the fixing roller 61a.

  The pressure roller 61b has a configuration in which an elastic layer made of silicone rubber or the like is formed on the outer peripheral surface of a cylindrical metal core made of iron or the like. Further, since the surface of the pressure roller 61b is relatively hard with respect to the surface of the fixing roller 61a, the pressure roller 61b is pressed against the elastic layer on the surface of the fixing roller 61a while being pressed against the fixing roller 61a. A nip portion N having a biting shape is formed.

  On the other hand, the cleaning mechanism that removes the paper dust generated by the fixing process and adhering to the fixing roller 61a by bringing the cleaning web W as a cleaning means into contact with the fixing roller 61a includes a cleaning web feeding roller 61f and a pressing force. A pressing roller 61g as a means and a cleaning web take-up roller 61h as a take-up means are provided.

  As shown in FIG. 3, the cleaning web W fed from the cleaning web feed roller 61f is pressed against the fixing roller 61a by the pressing roller 61g to remove paper dust adhering to the fixing roller 61a. The cleaning web W from which the paper dust adhering to the fixing roller 61a has been removed is taken up and collected by the cleaning web take-up roller 61h.

  The storage unit 62 is a storage device such as a nonvolatile memory, for example. The storage unit 62 stores information preset by the user, such as the image forming speed of the paper M conveyed to the fixing device 6 and the paper making direction of the paper M. The paper making direction indicates the direction of the fiber of the paper formed in the paper manufacturing process, and this fiber direction is also referred to as the “paper eye direction”. Further, the function of the storage unit 62 may be provided in the RAM 73 or the like constituting the control unit 7 without providing the storage unit 62 separately. Further, the storage unit 62 stores information on the winding amount and the pressing force set in advance in three stages, which will be described later.

  The winding amount adjustment unit 63 adjusts the winding amount of the cleaning web W under the control of the control unit 7. For example, driving means such as a driving motor for adjusting the rotation amount of the cleaning web feed roller 61f and the cleaning web take-up roller 61h constituting the cleaning mechanism.

  The pressing force adjusting unit 64 adjusts the pressing force of the cleaning web W to the fixing roller 61 a under the control of the control unit 7. For example, the width of the nip portion N formed by the fixing roller 61a and the pressing roller 61g is adjusted by switching the pressing position of a pressing cam (not shown) that presses the pressing roller 61g constituting the cleaning mechanism, and the cleaning web. The pressing force of W to the fixing roller 61a is adjusted.

  The distance acquisition unit 65 acquires a distance between the paper feed roller of the paper feed tray and the nip portion N or a registration roller located in the vicinity of the nip portion N. For example, the distance between the paper feed roller and the registration roller may actually be detected by the conveyance speed of the paper M and an optical sensor such as a photodiode provided in the vicinity of the paper feed roller and the registration roller. The distance information from the sheet feeding tray units 51a to 51c may be stored in advance in the storage unit 62 or the like, and the distance information may be acquired from the storage unit 62 or the like.

  The paper width acquisition unit 66 acquires the paper width of the paper M conveyed to the fixing device 6. For example, the paper width of the paper M may be actually detected by an optical sensor such as a photodiode array, or the paper width information of the paper M being fed to the paper feed tray units 51a to 51c may be detected from the transport unit 5 or the like. You may acquire.

The control unit 7 includes, for example, a CPU (Central Processing Unit) 71, a ROM (Read Only Memory) 72, a RAM (Random Access Memory) 73, and the like.
The CPU 71 reads a program corresponding to the processing content from the ROM 72 and expands it in the RAM 73, and cooperates with the expanded program in each block (the image reading unit 1, the operation display unit 2, and the image processing unit 3) of the image forming apparatus 100. The image forming unit 4, the conveying unit 5, the fixing device 6 and the like are centrally controlled. At this time, for example, various data stored in a storage unit (not shown) constituted by a nonvolatile semiconductor memory (flash memory) or a hard disk drive is referred to.

  Here, the control unit 7 is connected to an external communication network such as a LAN or a WAN (Wide Area Network) via a communication unit (not shown) configured by a LAN (Local Area Network) card, for example. Various data may be transmitted / received to / from an apparatus (for example, a personal computer).

  Further, the control unit 7 controls the storage unit 62, the winding amount adjustment unit 63, the pressing force adjustment unit 64, the distance acquisition unit 65, the paper width acquisition unit 66, and the like to obtain the paper making direction acquired from the storage unit 62. The winding amount adjusting unit 63 and the pressing force adjusting unit 64 are controlled based on the image forming speed and the acquisition result of each acquiring unit.

  Here, the operation of the fixing device 6 will be described with reference to FIGS. As shown in FIG. 4, the storage unit 62 stores winding amounts and pressing forces set in advance in three stages. For example, as the winding amount of the cleaning web W, the pressing force of the cleaning web W is defined by the width of the nip portion N formed by the fixing roller 61a and the pressing roller 61g as the energization time of the drive motor.

  Specifically, when the winding amount of the cleaning web W is “1”, the energization time of the drive motor is “200 msec / sheet”, and when the winding amount is “2”, the energization time of the drive motor is “270 msec / In the “sheet” and winding amount setting “3”, the energization time of the drive motor is defined as “330 msec / sheet”.

  That is, as the setting of the winding amount of the cleaning web W increases, the energization time of the drive motor becomes longer, the length of the cleaning web W to be wound becomes longer, and the cleaning ability for the fixing roller 61a becomes stronger.

  On the other hand, in the pressing force setting “1” of the cleaning web W, the width of the nip portion N formed by the fixing roller 61a and the pressing roller 61g is “3 mm”, and in the pressing force setting “2” of the cleaning web W, In the setting of “3 mm” for the width of the nip portion N and “3” for the pressing force of the cleaning web W, the width of the nip portion N is defined as “5 mm”.

  That is, as the setting of the pressing force of the cleaning web W is increased, the width of the nip portion N formed by the fixing roller 61a and the pressing roller 61g is increased, and the pressing force of the cleaning web W is increased, and the fixing roller 61a is pressed. Increases cleaning ability.

  Then, as shown in the flowchart of FIG. 5, the control unit 7 controls the distance acquisition unit 65 to acquire the distance between the paper feed roller and the registration roller, and the acquired distance is within a predetermined distance. Whether or not (step S501). Specifically, it is determined whether or not the acquired distance is within 476 mm.

  For example, as the distance between the paper feed roller and the registration roller is increased, the number of transport rollers (not shown) through which the paper M passes increases, so the load (the amount of friction, stress, etc.) that the paper M receives increases. Therefore, the amount of generated paper dust increases. For this reason, when it is more than the predetermined distance (476 mm) set beforehand, the necessity for increasing the cleaning capability by the cleaning web W arises.

  When the control unit 7 determines that the acquired distance is within the predetermined distance (step S501: Yes), the control unit 7 acquires information on the paper making direction from the storage unit 62, and whether or not the paper making direction is perpendicular to the transport direction. Is determined (step S502).

  For example, when the paper making direction is horizontal to the transport direction, the paper fibers that extend along the paper making direction are bent by the transport roller, etc., and the load that the paper M receives (the amount of friction, stress, etc.) increases. Therefore, the amount of generated paper dust increases. For this reason, when the paper making direction is horizontal to the transport direction, it becomes necessary to increase the cleaning capability of the cleaning web W.

  If the control unit 7 determines that the paper making direction is perpendicular to the transport direction (step S502: Yes), the control unit 7 acquires information on the image forming speed from the storage unit 62, and determines whether the image forming speed is equal to or lower than a predetermined speed. Is determined (step S503). Specifically, it is determined whether the image forming speed is 290 mm / sec or less. If the control unit 7 determines that the paper making direction is not perpendicular to the transport direction (step S502: No), the process proceeds to step S507.

  For example, when the image forming speed is higher than a predetermined speed, the rotation speed of the transport roller is also increased, and the load (rubbed amount, stress, etc.) received by the paper M is increased, so that the amount of generated paper dust increases. . For this reason, when it is more than the preset predetermined touch (290 mm / sec), it becomes necessary to increase the cleaning capability of the cleaning web W.

  When the control unit 7 determines that the image forming speed is equal to or lower than the predetermined speed (step S503: Yes), the control unit 7 controls the paper width acquisition unit 66 to acquire the paper width of the paper M, and the difference from the previous paper width. It is determined whether or not is a positive value (step S504). Specifically, it is determined whether the paper width is narrower than the previous paper width or whether the paper widths are equal. If the control unit 7 determines that the image forming speed is higher than the predetermined speed (step S503: No), the control unit 7 proceeds to step S508.

  For example, when the paper width is wider than the previous paper width, when fixing the previous paper with a narrow paper width, paper dust at the edge of the paper in the direction orthogonal to the paper transport direction adheres to the fixing roller, and the fixing roller When the fixing process is performed on a wide paper with the fixing roller in such a state, the trace of the paper edge is transferred to the wide paper. As a result, the wide paper is soiled. For this reason, when the paper width is wider than the previous paper width, it becomes necessary to increase the cleaning capability of the cleaning web W.

  When the control unit 7 determines that the difference from the previous paper width is a positive value (step S504: Yes), the winding amount and the pressing amount of the cleaning web W are set to “1” in FIG. (Step S505), the process proceeds to Step S516. Further, when the control unit 7 determines that the difference from the previous paper width is a negative value (step S504: No), the control unit 7 proceeds to step S509.

  On the other hand, when the control unit 7 determines that the acquired distance is not within the predetermined distance (step S501: No), the control unit 7 acquires the paper making direction information from the storage unit 62, and the paper making direction is perpendicular to the transport direction. Whether or not (step S506).

  If the control unit 7 determines that the paper making direction is perpendicular to the transport direction (step S506: Yes), the control unit 7 acquires information on the image forming speed from the storage unit 62, and determines whether the image forming speed is equal to or lower than a predetermined speed. Is determined (step S507).

  When the control unit 7 determines that the image forming speed is equal to or lower than the predetermined speed (step S507: Yes), the control unit 7 controls the paper width acquisition unit 66 to acquire the paper width of the paper M, and the difference from the previous paper width. Whether or not is a positive value is determined (step S508). If the control unit 7 determines that the image forming speed is equal to or higher than the predetermined speed (step S507: No), the control unit 7 proceeds to step S511.

  When the control unit 7 determines that the difference from the previous paper width is a positive value (step S508: Yes), the control unit 7 changes the winding amount of the cleaning web W to “2” in FIG. Maintaining “1” in FIG. 4 (step S509), the process proceeds to step S516. If the control unit 7 determines that the difference from the previous paper width is a negative value (step S508: No), the control unit 7 proceeds to step S512.

  Further, when the control unit 7 determines that the paper making direction is not perpendicular to the transport direction (step S506: No), the control unit 7 acquires information on the image forming speed from the storage unit 62, and the image forming speed is equal to or lower than a predetermined speed. Is determined (step S510).

  When the control unit 7 determines that the image forming speed is equal to or lower than the predetermined speed (step S510: Yes), the control unit 7 controls the paper width acquisition unit 66 to acquire the paper width of the paper M, and the difference from the previous paper width. It is determined whether or not is a positive value (step S511).

  When the control unit 7 determines that the difference from the previous paper width is a positive value (step S511: Yes), the control unit 7 changes the winding amount of the cleaning web W to “3” in FIG. Maintaining “1” in FIG. 4 (step S512), the process proceeds to step S516. If the control unit 7 determines that the difference from the previous paper width is a negative value (step S511: No), the control unit 7 proceeds to step S514.

  Finally, when the control unit 7 determines that the image formation speed is equal to or higher than the predetermined speed (step S510: No), the control unit 7 controls the paper width acquisition unit 66 to acquire the paper width of the paper M, and the previous paper width. It is determined whether or not the difference between is a positive value (step S513).

  When the control unit 7 determines that the difference from the previous paper width is a positive value (step S513: Yes), the control unit 7 changes the winding amount of the cleaning web W to “3” in FIG. It changes to “2” in FIG. 4 (step S514), and proceeds to step S516.

  If the control unit 7 determines that the difference from the previous paper width is a negative value (step S513: No), the control unit 7 changes the winding amount of the cleaning web W to “3” in FIG. The pressure is changed to “3” in FIG. 4 (step S515), and the process proceeds to step S516.

  Then, the controller 7 performs a fixing process to fix the toner image transferred onto the paper M (step S516). After the fixing process is completed, the winding amount and the pressing force of the cleaning web W are set to “1” in FIG. (Step S517), and the process ends.

  Here, in FIG. 6, the above-described web winding amount and web pressing force are switched in three stages, respectively, so that the cleaning capability switching control is performed in Embodiments 1 and 2, and the cleaning capability switching control is performed. In Comparative Example 1 and Comparative Example 2 that were not performed, the presence or absence of occurrence of paper stains due to paper dust adhering to the fixing roller 61a was compared.

  In contrast to the determination condition shown in FIG. 6A, in the first embodiment, only condition 2 is “No”. Therefore, from the flowchart of FIG. 5, the web winding amount is changed from “1” to “2”, the web winding amount is increased by one step, and the web pressing force is maintained at the minimum value of “1”. A cleaning capability is selected. On the other hand, Comparative Example 1 remains the minimum value of “1” together with the web winding amount and the web pressing force.

  In Example 1 and Comparative Example 1 in FIG. 6B, paper stains occurred in Comparative Example 1, and no paper stains occurred in Example 1. In Example 1 and Comparative Example 1, side effects such as deformation of the pressure roller 61g and generation of scratches on the surface of the fixing roller 61a due to insufficient removal of paper dust from the fixing roller 61a did not occur.

  In contrast to the determination condition shown in FIG. 6A, in the second embodiment, all the conditions 1 to 4 are “No”. Therefore, the web winding amount is changed from “1” to “3” from the flowchart of FIG. 5, the web winding amount is increased to the maximum value, and the web pressing force is changed from “1” to “3”. The cleaning capacity that is changed and the web pressing force increases to the maximum value is selected. On the other hand, in Comparative Example 2, the minimum value of “1” remains with the web winding amount and the web pressing force.

  In Example 2 and Comparative Example 2 in FIG. 6B, paper stains remarkably occurred in Comparative Example 2, and paper stains did not occur in Example 2. In Example 2 and Comparative Example 2, side effects such as deformation of the pressing roller 61g and generation of scratches on the surface of the fixing roller 61a due to insufficient removal of paper dust from the fixing roller 61a did not occur.

  Further, in the third embodiment, conditions 1 and 4 are “No” with respect to the determination condition illustrated in FIG. Therefore, the web winding amount is changed from “1” to “3” from the flowchart of FIG. 5, the web winding amount is increased to the maximum value, and the web pressing force is the minimum value of “1”. The cleaning capacity maintained is selected. On the other hand, Comparative Example 3 remains the minimum value of “1” together with the web winding amount and the web pressing force.

  In Example 3 and Comparative Example 3 in FIG. 6B, paper stains occurred in Comparative Example 3, and no paper stains occurred in Example 3. Further, in Example 3 and Comparative Example 3, there was no side effect such as the deformation of the pressing roller 61g and the occurrence of scratches on the surface of the fixing roller 61a due to insufficient removal of the paper dust from the fixing roller 61a.

  Further, in the fourth embodiment, conditions 2 to 4 are “No” with respect to the determination conditions illustrated in FIG. Therefore, the web winding amount is changed from “1” to “3” from the flowchart of FIG. 5, the web winding amount is increased to the maximum value, and the web pressing force is changed from “1” to “2”. The cleaning capacity that has been changed and the web pressing force increased is selected. On the other hand, Comparative Example 4 remains the minimum value of “1” together with the web winding amount and the web pressing force.

  In Example 4 and Comparative Example 4 in FIG. 6B, paper stains occurred significantly in Comparative Example 4 and no paper stains occurred in Example 4. In Example 4 and Comparative Example 4, side effects such as deformation of the pressing roller 61g and generation of scratches on the surface of the fixing roller 61a due to insufficient removal of paper dust from the fixing roller 61a did not occur.

Further, in the flowchart of FIG. 5, as a plurality of factors that generate paper dust, the cleaning ability switching control is performed by determining all the conditions of the paper making direction, the image forming speed, and the difference between the current paper width and the previous paper width. However, it is not necessary to perform switching control of the cleaning ability based on all judgments. Cleaning ability switching control may be performed based on determination of two or more conditions among a plurality of factors that generate paper dust. However, if all the conditions of the factors that generate paper dust are determined, the accuracy of the degree of paper dust adhering to the fixing roller 61a can be improved, so that the selection of the paper dust cleaning ability is set more appropriately. Can do.
Further, the plurality of factors that generate paper dust are not limited to these because they vary depending on differences in the image forming apparatus and the type of paper used.

  That is, by switching the web winding amount and the web pressing force finely in three stages (a plurality of stages), it is possible to select a cleaning capability suitable for the paper conditions such as the paper width in the direction orthogonal to the paper conveyance direction. .

  For this reason, compared with Patent Document 2 in which the cleaning ability is simply switched in two steps (increase / decrease), paper dust adhering to the fixing roller 61a can be accurately removed, the deformation of the pressing roller 61g, There is no possibility of causing side effects such as scratches on the surface of the fixing roller 61a due to insufficient removal of paper dust.

  As described above, the storage unit 62 storing the paper making direction and the image forming speed set in advance, the winding amount adjusting unit 63 for adjusting the winding amount of the cleaning web, and the pressing force of the cleaning web are adjusted. The pressing force adjusting unit 64, the distance acquiring unit 65 that acquires the distance to the paper feed tray, the paper width acquiring unit 66 that acquires the paper width in the direction orthogonal to the paper transport direction, and the paper making direction acquired from the storage unit 62. And a control unit 7 that controls the winding amount adjustment unit 63 and the pressing force adjustment unit 64 based on the image formation speed and the acquisition results of the distance acquisition unit 65 and the paper width acquisition unit 66, thereby generating a plurality of paper dusts. Since the optimum combination can be selected based on the above factors, paper dust adhering to the fixing roller 61a can be removed, and paper smear does not occur.

  Further, since an optimal combination can be selected based on a plurality of factors that generate paper dust, paper dust attached to the fixing roller 61a can be removed, and the deformation of the pressing roller 61g and the paper dust from the fixing roller 61a can be removed. Due to the insufficient removal, no side effects such as scratches on the surface of the fixing roller 61a occur.

  In the description of the embodiment, the fixing device 6 includes a fixing roller 61a and a pressure roller 61b that constitute a nip portion N that sandwiches and conveys the paper M, but a heating roller that is a heating member; A fixing belt, and the fixing belt is stretched between a heating roller and a fixing roller 61a, and the fixing roller 61a and the pressure roller 61b sandwich and convey the paper M via the fixing belt. N may be configured.

  In the description of the embodiment, for example, a unit for image formation is provided for each color such as Y (yellow), M (magenta), C (cyan), K (black), and a color image is formed on the paper M. The image forming apparatus 100 to be formed is illustrated as an example, but the present invention is not limited to this. For example, an image forming apparatus that forms a monochrome image may be used.

  In the description of the embodiment, the fixing roller and the pressure roller are described separately, but may be considered as a pair of fixing members.

  In the description of the embodiment, the web winding amount and the web pressing force are each set in three stages, and the cleaning ability suitable for the paper condition such as the paper width in the direction orthogonal to the paper conveyance direction is selected. However, the amount of web winding and the web pressing force may be three or more stages.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 4 Image forming part 6 Fixing apparatus 61 Fixing part 61a Fixing roller 61b Pressure roller 61c Outer heating roller 61d Fixing heater 61e Outer heating heater 61f Sending roller 61g Pressing roller (pressing means)
61h Winding roller (winding means)
62 Storage Unit 63 Winding Amount Adjustment Unit 64 Pressing Force Adjustment Unit 65 Distance Acquisition Unit 66 Paper Width Acquisition Unit 7 Control Unit M Paper (Recording Medium)
N nip W cleaning web (cleaning means)

Claims (8)

In a fixing device for fixing a toner image on a sheet by passing the sheet on which the toner image is formed through a nip formed by heating and pressing at least one of a pair of fixing members.
Cleaning means for cleaning the surface of the fixing member;
Pressing means for pressing the cleaning means against the surface of the fixing member;
A winding means for winding and collecting the cleaning means;
A winding amount adjusting unit for adjusting a winding amount of the cleaning unit by the winding unit;
A pressing force adjusting unit that adjusts the pressing force of the cleaning unit by the pressing unit;
A control unit that controls the winding amount adjustment unit and the pressing force adjustment unit based on two or more conditions among a plurality of conditions related to image formation;
A fixing device comprising:   When the control unit determines that paper dust increases due to the two or more conditions, the winding amount adjustment unit and the pressure adjustment so as to increase at least one of the pressing force and the winding amount. The fixing device according to claim 1, wherein the fixing unit is controlled.   The conditions are orthogonal to the distance from the paper feed tray to which the paper is fed to the nip or the vicinity of the nip, the orientation of the paper in the paper making direction with respect to the transport direction, the image forming speed, or the paper transport direction. The fixing device according to claim 1, wherein the fixing device has a paper width in the direction in which the paper is to be pressed.   The control unit is configured to determine the winding amount set in advance in a plurality of stages based on the length of the distance, the direction of the paper making direction, the image forming speed, and the difference between the paper width and the paper width at the time of the previous fixing process. The fixing device according to claim 3, wherein the fixing device is controlled by selecting and combining each of the pressing forces set in a plurality of stages.   The control unit is configured such that the distance is within a predetermined distance, the paper making direction is perpendicular to the transport direction, the image forming speed is equal to or lower than a predetermined speed, and the difference between the paper width and the paper width at the previous fixing process is positive. 5. The fixing device according to claim 4, wherein when it is determined that the value is a value, a minimum value among a plurality of levels is selected and controlled as the winding amount and the pressing force.   The control unit is configured such that the distance is equal to or greater than a predetermined distance, the paper making direction is parallel to the transport direction, the image forming speed is faster than a predetermined speed, and the difference between the paper width and the paper width at the previous fixing process is negative. 5. The fixing device according to claim 4, wherein when it is determined that the value is a maximum value, a maximum value among a plurality of values is selected and controlled as the winding amount and the pressing force.   7. The fixing device according to claim 4, wherein the control unit returns the winding amount and the pressing force to a minimum value among a plurality of stages after the fixing process is completed. . An image forming unit that forms a toner image on paper;
The fixing device according to any one of claims 1 to 7, wherein the toner image is fixed to the paper through the paper on which the toner image is formed;
An image forming apparatus comprising:

Images