JP2017173724A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to prevent a mixture of toner and paper powder from adversely affecting fixing rotating bodies and soaking rotating bodies.SOLUTION: An image forming apparatus 1 of the present invention comprises fixing devices 5 that each cause a recording material P having an unfixed toner image attached thereto to pass through a fixing nip part 33 formed by fixing rotation body pair 31 and 32. The image forming apparatus includes: soaking rotating bodies 41 that each are in contact with one of the fixing rotating pair 31 and 32 to make uniform a temperature distribution in a paper feed width direction; cleaning rotating bodies 42 that are each in contact with the soaking rotating body 41 to clean the same; paper powder amount detection means that detects the amount of paper powder transferred to the soaking rotating bodies 41; and rotation control means 28 that controls the rotation of the cleaning rotating bodies 42 on the basis of detection information from the paper powder amount detection means.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image forming apparatus including a fixing device that allows a recording material with an unfixed toner image to pass through a fixing nip formed by a pair of fixing rotators to fix the recording material. The image forming apparatus includes various apparatuses such as a copying machine, a printer, a facsimile machine, and a multifunction machine having these functions in a complex manner.

  2. Description of the Related Art Conventionally, an image forming apparatus that employs an electrophotographic system includes a fixing device that allows a recording material with an unfixed toner image to pass through a fixing nip formed by a heating rotator and a pressure rotator to fix the image. In this type of fixing method, the recording material is heated and pressurized through the fixing nip portion, whereby the toner image is melted and the toner image is fixed on the recording material.

  The fixing device includes a soaking rotator that contacts the pressure rotator and uniforms the temperature distribution in the sheet passing width direction, and a cleaning rotator that contacts the soaking rotator and cleans it. There are some (see, for example, Patent Document 1). The soaking rotator prevents problems of fixing unevenness and paper wrinkles due to temperature unevenness of the heating rotator and the pressure rotator. Since the soaking rotator is in contact with the pressurizing rotator, a residue such as toner or paper powder adhered to the pressurizing rotator may be transferred to the soaking rotator. Then, the residue which the cleaning rotary body transferred to the soaking rotary body is removed.

JP 2010-97017 A

  The toner and paper dust collected on the cleaning rotator are agitated into a mixture depending on the rotation speed of the cleaning rotator. The mixture exhibits different viscosities depending on the ratio of toner to paper dust. For example, when the paper powder ratio is large (toner ratio is small), a mixture with low viscosity is generated, and when the toner ratio is large (paper powder ratio is small), a mixture with high viscosity is generated.

  Since the mixture having a large paper powder ratio has low viscosity, the mixture may be separated from the cleaning rotating body by impact or the like, and may return to the soaking rotary body or the pressure rotating body. What has returned and transferred to the soaking rotator is recovered again by the cleaning rotator, but what has returned and transferred to the pressurizing rotator is pressed by the nip between the pressurizing rotator and the soaking rotator. Easily stays in the pressure rotating body. A mixture having a large paper powder ratio staying in the pressure rotator hardly adheres to the recording material at the fixing nip due to its low viscosity. In addition, since the mixture having a large paper powder ratio retained in the pressure rotator is poor in releasability, there is a problem that the mixture tends to grow as dirt on the pressure rotator.

  On the other hand, a mixture having a large toner ratio tends to adhere not only to the cleaning rotary body but also to the soaking rotary body because of its high viscosity. If the adhering amount of the mixture to the soaking rotator increases, it will surpass the removal capability of the cleaning rotator, and the mixture will grow as dirt on the soaking rotator and damage the surface of one fixing rotator that comes into contact with it. In other words, there is a problem that a lump of dirt flows back to the fixing nip portion and stains the recording material, so-called discharge dirt is generated.

  This invention makes it a technical subject to eliminate said problem.

  According to a first aspect of the present invention, there is provided an image forming apparatus including a fixing device that allows a recording material with an unfixed toner image to pass through a fixing nip portion formed by a fixing rotating body pair and fixes the recording material. A soaking rotator that contacts one side to make the temperature distribution in the paper passing width direction uniform, a cleaning rotator that contacts and cleans the soaking rotator, and an amount of paper powder transferred to the soaking rotator And a rotation control means for controlling the rotation of the cleaning rotating body based on the detection information of the paper dust amount detection means.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect of the present invention, the image forming apparatus further includes a toner amount detection unit that detects a toner amount transferred to the soaking rotator, and the rotation control unit detects the paper dust amount The rotation of the cleaning rotating body is controlled based on the detection information of the toner amount detection means in addition to the detection information of the means.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the cleaning rotator is configured to be rotatable forward and backward.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the rotational speed of the cleaning rotator is configured to be variable.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the paper dust amount detection means transfers the paper dust transferred to the soaking rotator based on information on the paper type of the recording material used for printing. It is to detect the amount.

  According to a sixth aspect of the present invention, in the image forming apparatus according to the first aspect, the paper dust amount detecting means is a paper that is transferred to the soaking rotator on the basis of information on the number of sheets of a recording material to be printed. The amount of powder is detected.

  According to a seventh aspect of the present invention, in the image forming apparatus according to the first or second aspect, the rotation control unit sets the fixing rotator to a fixing temperature higher than normal after the end of printing or execution of a predetermined number of prints. The pair is idled.

  According to an eighth aspect of the present invention, in the image forming apparatus according to the first aspect, the paper dust amount detection unit detects a paper dust amount attached to a rotating member that conveys the recording material, and the rotating member. And a cleaning blade body disposed on the rotation downstream side of the photosensor on the outer peripheral side of the photosensor.

  According to a ninth aspect of the present invention, in the image forming apparatus according to the second aspect, the toner amount detecting means detects the amount of toner transferred to the soaking rotator based on information on a printing rate, a use environment, and a fixing temperature. That's it.

  According to the present invention, the soaking rotator that makes contact with any one of the fixing rotator pair and uniformizes the temperature distribution in the sheet passing width direction, and the cleaning rotator that makes contact with the soaking rotator and cleans it. The paper dust amount detecting means for detecting the amount of paper dust transferred to the soaking rotator, and the rotation control means for controlling the rotation of the cleaning rotating body based on the detection information of the paper dust amount detecting means, Regardless of the various printing conditions, it is possible to avoid image defects due to dirt on each fixing rotator, damage to the surface of the fixing rotator contacting the soaking rotator, etc. Long life can be achieved.

1 is a schematic explanatory diagram of a printer according to a first embodiment. 1 is a cross-sectional view illustrating a fixing device according to a first embodiment. It is a functional block diagram of a control part in a 1st embodiment. It is a rotation setting table of 1st Embodiment. It is a schematic explanatory drawing of the printer which concerns on 2nd Embodiment. It is a functional block diagram of a control part in a 2nd embodiment. It is a dirt diagnostic table of a 2nd embodiment. It is a use environment correction table of 2nd Embodiment. It is a fixing temperature correction table of the second embodiment. It is a rotation setting table of 2nd Embodiment.

  DESCRIPTION OF EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings (FIGS. 1 to 10). In addition, in the following description, when using a term indicating a specific direction or position (for example, “left / right”, “up / down”, etc.) as necessary, the direction orthogonal to the paper surface in FIG. ing. These terms are used for convenience of explanation, and do not limit the technical scope of the present invention.

  First, the outline of the printer 1 will be described with reference to FIG. The printer 1 of the first embodiment is a tandem color digital printer (hereinafter simply referred to as a printer). As shown in FIG. 1, the printer 1 includes an image process device 3, a paper feeding device 4, a fixing device 5, and the like in a housing 2. Although not shown, the printer 1 is connected to a network such as a LAN, for example, and receives a print job from an operation panel 48 (see FIG. 3) as an operation display unit or an external terminal (not shown). It is configured to execute printing based on the job.

  The paper feeding device 4 located at the lower part in the housing 2 includes a paper feeding cassette 21 that accommodates the recording material P, a pickup roller 22 that feeds the recording material P in the paper feeding cassette 21 from the uppermost layer, and a fed recording material P. A pair of separation rollers 23 for separating the recording materials one by one, a pair of timing rollers 24 for conveying the recording material P separated into one sheet to the image processing apparatus 3 at a predetermined timing, and the like. The recording material P in each paper feed cassette 21 is sent out one by one from the uppermost layer to the transport path 30 by the rotation of the pickup roller 22 and the separation roller 23. The conveyance path 30 passes from the paper feed cassette 21 of the paper feed device 4 to the casing 2 through the nip portion of the timing roller pair 24, the secondary transfer nip portion of the image processing device 3, and the fixing nip portion 33 of the fixing device 5. It reaches the discharge roller pair 26 at the top.

  The recording material P in the paper feed cassette 21 is set to a center reference that is conveyed in the arrow S direction toward the conveyance path 30 with the center of the sheet passing width (width dimension orthogonal to the arrow S direction) as a reference. Although illustration is omitted, the paper feed cassette 21 is provided with a pair of side part regulating plates for bringing the recording material P before paper feeding closer to the center. The pair of side regulating plates are configured to move in a close-up manner in conjunction with each other in the sheet passing width direction. By sandwiching the recording material P in the paper feed cassette 21 from both sides in the sheet passing width direction by the pair of side portion regulating plates, the recording material P in the paper feed cassette 21 is set to the center reference regardless of the standard. Therefore, the transfer process in the image processing apparatus 3 and the fixing process in the fixing apparatus 5 are also executed on the basis of the center.

  The image processing device 3 positioned above the paper feeding device 4 plays a role of transferring a toner image formed on a photosensitive drum 13 which is an example of an image carrier to a recording material P, and is an intermediate transfer member. And a total of four image forming sections 7 corresponding to the respective colors of yellow (Y), magenta (M), cyan (C) and black (K).

The intermediate transfer belt 6 is an endless belt made of a conductive material, and is also an example of an image carrier. The intermediate transfer belt 6 is wound around a driving roller 8 located on the right side of the central part in the housing 2 and a driven roller 9 located on the left side of the central part. A secondary transfer roller 10 is disposed outside the portion of the intermediate transfer belt 6 that is wound around the drive roller 8. The intermediate transfer belt 6 rotates in the counterclockwise direction in FIG. 1 by rotating the driving roller 8 counterclockwise in FIG. 1 by power transmission from a main motor (not shown).

  A secondary transfer roller 10 is disposed on the outer peripheral side of the portion of the intermediate transfer belt 6 that is wound around the drive roller 8. The secondary transfer roller 10 is in contact with the intermediate transfer belt 6, and a portion between the intermediate transfer belt 6 and the secondary transfer roller 10 (contact portion) is a secondary transfer nip portion as a secondary transfer region. . The secondary transfer roller 10 rotates in the clockwise direction in FIG. 1 with the rotation of the intermediate transfer belt 6 or with the movement of the recording material P that is nipped and conveyed by the secondary transfer nip portion. A transfer belt cleaner 12 for removing untransferred toner on the intermediate transfer belt 6 is disposed on the outer peripheral side of the portion of the intermediate transfer belt 6 wound around the driven roller 9. The transfer belt cleaner 12 is in contact with the intermediate transfer belt 6.

  The four image forming units 7 are arranged along the intermediate transfer belt 6 in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the left in FIG. They are arranged side by side. In FIG. 1, for convenience of explanation, symbols Y, M, C, and K are attached to each image forming unit 7 according to the reproduction color. Each image forming unit 7 includes a photosensitive drum 13 as an example of an image carrier that rotates in the clockwise direction in FIG. Around the photosensitive drum 13, a charging device 14, an exposure device 19, a developing device 15, a primary transfer roller 16, and a photosensitive cleaner 17 are arranged in this order along the clockwise rotation direction in FIG. 1.

  The photosensitive drum 13 is negatively charged and is configured to rotate clockwise in FIG. 1 by power transmission from the main motor. The charging device 14 uniformly charges the surface of the photosensitive drum 13. The developing device 15 converts the electrostatic latent image formed on the photosensitive drum 13 by reversal development using toner having a negative polarity.

  The primary transfer roller 16 is located on the inner peripheral side of the intermediate transfer belt 6 and faces the photosensitive drum 13 of the corresponding image forming unit 7 with the intermediate transfer belt 6 interposed therebetween. The primary transfer roller 16 also rotates counterclockwise in FIG. 1 as the intermediate transfer belt 6 rotates. Between the intermediate transfer belt 6 and the primary transfer roller 16 (contact portion) is a primary transfer nip portion as a primary transfer region. The photoreceptor cleaner 17 is for removing untransferred toner remaining on the photoreceptor drum 13, and is in contact with the photoreceptor drum 13. An exposure device 19 is disposed below the four image forming units 7. The exposure device 19 forms an electrostatic latent image on each photosensitive drum 13 by laser light based on image data from an external terminal or the like.

  Above the intermediate transfer belt 6, bottle accommodating portions 39 corresponding to the respective image forming portions 7 (reproduced colors) are provided. A toner bottle 40 that contains toner supplied to each developing device 15 is detachably disposed in the bottle storage unit 39. In FIG. 1, for convenience of explanation, the bottle accommodating portion 39 and the toner bottle 40 are also denoted by symbols Y, M, C, and K according to the reproduced colors.

In each image forming unit 7, when a laser beam corresponding to an image signal is projected from the exposure device 19 onto the photosensitive drum 13 charged by the charging device 14, an electrostatic latent image is formed. The electrostatic latent image is reversely developed with toner supplied from the developing device 15 and becomes a toner image of each color. The toner images on the respective photosensitive drums 13 are primarily transferred from the photosensitive drum 13 to the outer peripheral surface of the intermediate transfer belt 6 in the order of yellow, magenta, cyan, and black at the corresponding primary transfer nip portions, and are superimposed. . Untransferred toner remaining on the photosensitive drum 13 is scraped off by the photosensitive cleaner 17 and removed from the photosensitive drum 13. When the recording material P passes through the secondary transfer nip portion, the superimposed four color toner images are secondarily transferred onto the recording material P all at once. Untransferred toner remaining on the intermediate transfer belt 6 is scraped off by the transfer belt cleaner 12 and removed from the intermediate transfer belt 6.

  The fixing device 5 positioned above the secondary transfer roller 10 includes a fixing roller 31 and a pressure roller 32. A contact portion between the fixing roller 31 and the pressure roller 32 is a fixing nip portion 33 which is a fixing region. The recording material P on which an unfixed toner image is placed after passing through the secondary transfer nip portion is heated and pressurized when passing through the fixing nip portion 33 between the fixing roller 31 and the pressure roller 32, and the recording material P A toner image is fixed on P. The recording material P after passing through the fixing nip portion 33 is separated from the fixing roller 31 by the separation member 34 provided on the downstream side of the fixing nip portion 33, and after being conveyed on the conveyance path 30, The paper is discharged onto the paper discharge tray 27 by rotation.

  Between the image processing device 3 and the paper feeding device 4 inside the housing 2, a control unit 28 that controls the overall control of the printer 1 is disposed.

  Next, the details of the fixing device 5 will be described with reference to FIG. The fixing device 5 includes a fixing roller 31 extending in the sheet passing width direction and having rotation axes parallel to each other, a pressure roller 32, a soaking roller 41 as a soaking rotator, and a rotating brush 42 as a cleaning rotator. Yes. Both ends of the fixing roller 31, the pressure roller 32, the soaking roller 41, and the rotating brush 42 are rotatably supported by respective bearing members. The pressure roller 32 is biased toward the fixing roller 31 by biasing means such as a spring. A pressure roller 32 is pressed against the fixing roller 31.

  More specifically, an endless fixing belt 37 is wound around the outer peripheral side of the fixing roller 31. The fixing belt 37 has a cylindrical shape that is long in the sheet passing width direction, and holds the cylindrical shape by the fixing roller 31 and its own tension. The fixing belt 37 includes a release layer, an elastic layer having elasticity, and a heat generation layer in order from the outside. The heat generating layer of the fixing belt 37 is heated by induction heating of the heating unit 35 described later. A combination of the fixing roller 31 (including the fixing belt 37) and the pressure roller 32 constitutes a fixing rotating body pair.

  A fixing nip portion 33 is formed between the fixing roller 31 (fixing belt 37) and the pressure roller 32. The recording material P onto which the toner image has been transferred passes through the fixing nip portion 33, whereby the toner image is fixed on the recording material P. In this case, the recording material P is conveyed so that the surface of the recording material P to which the toner image is transferred is in contact with the fixing roller 31 (fixing belt 37). The toner image is heated and melted by the fixing roller 31 (fixing belt 37) and fixed on the recording material P.

  In FIG. 2, the rotation direction of the fixing roller 31 (fixing belt 37) and the pressure roller 32 and the conveyance direction of the recording material P are indicated by solid arrows. Power is transmitted from a pressure motor (not shown) as a drive source to a pressure roller 32 via a power transmission system such as a gear or a belt, and the pressure roller 32 is rotationally driven in the clockwise direction in FIG. With the rotation of the pressure roller 32 and the recording material P passing through the fixing nip portion 33, the fixing roller 31 and the fixing belt 37 are opposite to the rotation direction of the pressure roller 32 due to the pressure friction force (counterclockwise direction in FIG. 2). Rotate to.

A heating unit 35 is disposed on the downstream side of the fixing nip 33 in the rotation direction of the fixing roller 31 (fixing belt 37). The heating unit 35 of the first embodiment is a magnetic flux generation unit having an exciting coil 36 wound over the fixing belt 37 in the width direction, and heats the heat generation layer of the fixing belt 37 by induction heating. A high frequency current of 20 to 90 kHz and 100 to 1500 W is supplied to the excitation coil 36 from a high frequency power source (not shown). An eddy current is induced in the heat generating layer of the fixing belt 37 by the magnetic flux induced by the exciting coil 36, the heat generating layer generates heat by Joule heat, and the fixing belt 37 is heated. Although not shown, a temperature sensor 38 is in contact with or close to the fixing belt 37. The fixing belt 37 is maintained at a predetermined fixing temperature by controlling the heating unit 35 according to the detection result of the temperature sensor 38.

  On the downstream side of the fixing nip portion 33 in the rotation direction of the pressure roller 32, a temperature-uniforming roller 41 that contacts the surface of the pressure roller 32 and equalizes the temperature distribution in the sheet passing width direction is disposed. The soaking roller 41 is biased toward the pressure roller 32 by a biasing means such as a spring. The soaking roller 41 rotates in the direction opposite to the rotation direction of the pressure roller 32 (counterclockwise in FIG. 2) by the pressure frictional force with the pressure roller 32. The soaking roller 41 used in the present invention only needs to have an effect of uniformizing the temperature distribution in the paper passing width direction of at least one of the fixing roller 31 (fixing belt 37) and the pressure roller 32. You may have heating means, such as a halogen heater, and heat dissipation means, such as a heat pipe.

  In the vicinity of the soaking roller 41, a rotating brush 42 that contacts the surface of the soaking roller 41 is rotatably provided. The rotating brush 42 is motive power transmitted from a brush motor 47, which is a dedicated drive source, via a power transmission system such as a gear or a belt, and can rotate forward and backward. Further, the rotational speed of the rotary brush 42 (drive speed of the brush motor 47) is variable.

  Next, details of the control unit 28 will be described with reference to FIG. The control unit 28 includes a communication interface (I / F) unit 51, an image processing unit 52, an image memory 53, a CPU 57, a ROM 58, a RAM 59, a counter 60, a timer 61, a backup memory 62, and the like as main components. . These units 51 to 53 and 57 to 62 are configured to be able to communicate with each other via a bus 65.

  The communication I / F unit 51 is an interface for connecting to a LAN such as a LAN card or a LAN board, receives print job data from the outside, and transmits the received data to the image processing unit 52. The image processing unit 52 converts the print job data from the communication I / F unit 51 into image data of each reproduction color, outputs the image data to the image memory 53, and stores the image data for each reproduction color.

  The CPU 57 reads a necessary program from the ROM 58, converts the image data in the image processing unit 52, writes / reads out the image data in the image memory 53, and takes the timing while processing the image processing device 3 and the paper feeding device. A smooth print job is executed by controlling operations such as 4. The CPU 57 receives a detection signal from the temperature sensor 38 that detects the temperature of the fixing device 5, and executes rotation control of various motors as a drive source, rotation control of the brush motor 47, and the like. Further, the CPU 57 also controls input / output of the operation panel 48 mounted on the outer surface side of the housing 2.

  The ROM 58 stores control programs related to printing operations, image stabilization processing, control programs related to toner replenishment processing, and the like, as well as reference pattern data for each color formed in the image stabilization processing. The RAM 59 is used as a work area for the CPU 57. The counter 60 counts the cumulative number of recording materials P used for printing (cumulative printing number) and stores the counted numerical value in a predetermined storage area of the backup memory 62.

  The timer 61 receives power supply from an internal battery (not shown) or the like and measures the drive time of various motors. The backup memory 62 is a non-volatile storage unit and stores the cumulative number of printed sheets. The control unit 28 constitutes a rotation control means for the rotating brush 42.

Next, an example of the cleaning rotation control executed by the control unit 28 will be described with reference to FIG. In the cleaning rotation control of the first embodiment, the amount of paper dust transferred to the soaking roller 41 is detected (
And the rotation direction and rotation speed of the rotary brush 42 are controlled from the amount of paper dust. In this case, the amount of paper dust transferred to the soaking roller 41 is input by the user from the operation panel 48 when the recording material P is accommodated in the paper feed cassette 21. The input mode on the operation panel 48 corresponds to the paper dust amount detecting means. The print rate is obtained from image data from a print job from the operation panel 48 or an external terminal. The printing rate calculation from the image data corresponds to the toner amount detecting means. Note that the paper dust amount corresponding to the paper type of the recording material P may be stored in the backup memory 62 in advance, and the control unit 28 may determine the paper dust amount according to the paper type selected by the user.

  In the cleaning rotation control of the first embodiment, when printing on the recording material P with a small amount of paper dust, regardless of the printing rate, the rotation setting table (see FIG. 4) stored in the backup memory 62 or the like is used. By rotating the brush motor 47, the rotating brush 42 is rotated in the same direction as the rotation direction of the soaking roller 41 (counterclockwise direction in FIG. 2). The rotation speed of the rotating brush 42 is set to be approximately the same as the rotation speed of the soaking roller 41 (the rotating speed ratio with respect to the soaking roller 41 is set to 1.0).

  In the nip portion between the soaking roller 41 and the rotating brush 42, both surfaces move in opposite directions (respective rotation directions in the nip portion are opposite to each other). For this reason, residues such as toner and paper dust adhering to the soaking roller 41 are surely scraped off by the rubbing of the rotating brush 42 and peeled off. When printing on the recording material P with a small amount of paper dust, since the paper powder itself transferred to the soaking roller 41 is small, a low-viscosity mixture composed of toner and paper powder is difficult to generate. Therefore, even if it is the rotation conditions of the rotating brush 42 in which toner and paper dust are likely to be mixed, the growth of the pressure roller 32 or the contamination itself can be suppressed.

  When printing on the recording material P having a large amount of paper dust, the brush motor 47 is driven based on the rotation setting table (see FIG. 4) to rotate in the direction opposite to the rotation direction of the soaking roller 41 (clockwise in FIG. 2). ) To rotate the rotating brush 42. The rotation speed of the rotating brush 42 is set to a speed higher than the rotation speed of the soaking roller 41 (the rotating speed ratio with respect to the soaking roller 41 is set to 1.1).

  At the nip portion between the temperature-uniforming roller 41 and the rotating brush 42, both surfaces move in the forward direction with each other (respective rotation directions at the nip portion are in the forward direction with each other). For this reason, the toner and paper powder transferred from the soaking roller 41 to the rotating brush 42 are difficult to mix, and a low-viscosity mixture consisting of toner and paper powder is difficult to generate. Accordingly, it is possible to reduce the retention of the mixture having low viscosity on the surface of the pressure roller 32, and it is possible to suppress the growth of dirt on the pressure roller 32 or the dirt itself.

  For example, when printing on the recording material P having a large amount of paper dust at a high printing rate, the amount of toner and the amount of paper dust transferred to the pressure roller 32 and the like by the fixing process increase. The amount of toner transferred to the pressure roller 32 or the like is equal to or greater than the amount of paper dust. For this reason, when the toner transferred from the soaking roller 41 to the rotating brush 42 and the paper dust are mixed, a highly viscous mixture composed of the toner and the paper dust is generated, and is easily fixed to the soaking roller 41. .

  Since this condition corresponds to the case of printing on the recording material P having a large amount of paper dust, as described above, the temperature-uniforming roller 41 is driven by the brush motor 47 based on the rotation setting table (see FIG. 4). The rotating brush 42 is rotated in the opposite direction (clockwise in FIG. 2). The rotation speed of the rotating brush 42 is set to a speed higher than the rotation speed of the soaking roller 41 (the rotating speed ratio with respect to the soaking roller 41 is set to 1.1).

However, since a highly viscous mixture is easily generated due to the large amount of toner, the amount of the mixture adhering to the soaking roller 41 is increased, surpassing the removal capability of the rotating brush 42, and the mixture becomes soaking roller. The possibility of growing as dirt on 41 cannot be denied. Therefore, when printing on the recording material P having a large amount of paper dust, the forced cleaning mode is executed after the printing is finished regardless of the printing rate.

  In the forced cleaning mode, after the printing of the recording material P having a large amount of paper dust, the heating belt 35 sets the fixing belt 37 higher than the fixing temperature (temperature during normal printing), and the pressure roller 32 is idled. The fixing roller 31 and the fixing belt 37 are idled in conjunction with the pressure roller 32. The execution time of the forced cleaning mode is, for example, about 1 minute. Further, if the forced cleaning mode is executed for about 30 seconds between the previous print job and the next print job and the cumulative number of printed sheets exceeds a predetermined number (for example, about 3000 sheets), the forced cleaning mode is set to about You may make it run for 1 minute.

  By causing the pair of fixing rotators (the fixing roller 31 (fixing belt 37) and the pressure roller 32) to idle at high temperature, the surface temperature of the pressure roller 32 rapidly increases, and accordingly, the surface of the temperature-uniforming roller 41 is increased. The temperature also rises. In this state, the rotating brush 42 is rotated in the direction opposite to the rotation direction of the soaking roller 41 (clockwise in FIG. 2). As a result, the toner adhering to the soaking roller 41 is melted and partly transferred to the pressure roller 32 and partly transferred to the rotating brush 42. The toner adhering to the rotating brush 42 is also melted and peeled off by the impact of the rotation of the rotating brush 42 itself and the contact with the soaking roller 41. The toner transferred to the pressure roller 32 transfers again to the soaking roller 41 or adheres to the subsequent recording material P. Since the toner adhering to the subsequent recording material P is extremely minute and dispersed, there is almost no possibility of being recognized as an image defect.

  As is clear from the above description, according to the first embodiment, image defects caused by contamination of the fixing roller 31 (including the fixing belt 37) and the pressure roller 32, and soaking, regardless of various printing conditions. The surface of the pressure roller 32 in contact with the roller 41 can be prevented from being damaged, and the growth of dirt can be suppressed to extend the life of the rollers 31, 32, 41 and the rotating brush 42.

  Note that the amount of paper powder transferred to the soaking roller 41 is not limited to be determined based on the paper type of the recording material P, and for example, the number of sheets of recording material P to be used for printing (the number of continuous prints) It may be determined on the basis of For example, it may be set when the amount of paper dust is large if the number of continuously printed sheets is 100 or more, and may be set when the amount of paper dust is small if it is less than 100.

  Next, the structure and control mode for cleaning rotating body control of the second embodiment will be described with reference to FIGS. In addition, in 2nd Embodiment, a code | symbol same as 1st Embodiment is attached | subjected to what does not change a structure and an effect | action from 1st Embodiment, and the detailed description is abbreviate | omitted. In the cleaning rotation control of the second embodiment, the toner amount is detected (estimated) in addition to the amount of paper dust transferred to the soaking roller 41, and the rotation direction of the rotary brush 42 and the relationship between the paper dust amount and the toner amount are detected. Control the rotation speed.

  As shown in FIG. 5, a photo sensor 49 that detects the amount of paper dust attached to the pickup roller 22 is disposed in the vicinity of the pickup roller 22 as a rotating member that conveys the recording material P. On the outer peripheral side of the pickup roller 22, a cleaning blade body 50 that contacts the pickup roller 22 is disposed on the downstream side of the photosensor 49. The cleaning blade body 50 is for removing paper dust from the surface of the pickup roller 22 after detection of the amount of paper dust by the photosensor 49 to prevent the cumulative detection of paper dust. The photo sensor 49 and the cleaning blade body 50 constitute paper dust amount detection means. The photo sensor 49 is electrically connected to the control unit 28 (see FIG. 6).

In the cleaning rotation control of the second embodiment, the amount of paper dust detected by the photosensor 49 is based on a stain diagnosis table (see FIG. 7) stored in the backup memory 62 or the like in a plurality of stages (in this case, in descending order). Ranks are divided into five levels. Therefore, it is not necessary for the user to determine whether or not the recording material P is rich in paper dust depending on the paper type and to input from the operation panel 48. The paper dust amount detection means (the photo sensor 49 and the cleaning blade body 50) is not limited to being disposed around the pickup roller 22. It is sufficient to arrange the recording material P around the rotating member (for example, the timing roller 24) in contact with the recording material P in the section of the conveyance path 30 until the recording material P reaches the fixing device.

  The amount of toner transferred to the temperature-uniforming roller 41 is detected (estimated) from the printing rate, and is ranked into a plurality of levels (in this case, 5 levels) in descending order of the printing rate based on the stain diagnosis table (see FIG. 7). The The print rate is obtained from image data from a print job from the operation panel 48 or an external terminal. The amount of toner transferred to the temperature-uniforming roller 41 depends on the use environment and the fixing temperature on the basis of the print rate. Therefore, the print rate is corrected using the use environment and the fixing temperature as parameters.

  Regarding the correction of the use environment, based on the use environment correction table (see FIG. 8) stored in the backup memory 62 or the like, the printing rate ± 0.5% per ± 1 ° C. of the temperature change of the use environment with respect to the reference temperature 20 ° C. Is added. Regarding the correction of the fixing temperature, based on the fixing temperature correction table (see FIG. 9) stored in the backup memory 62 or the like, the difference between the fixing temperature (set temperature) 170 ° C. and the temperature detected by the temperature sensor 38 is −. Add a printing rate of 0.25% per 5 ° C. The difference between the fixing temperature (set temperature) 170 ° C. and the temperature detected by the temperature sensor 38 subtracts a printing rate of 0.25% per + 5 ° C. As described above, it is determined that the amount of toner transferred to the soaking roller 41 is large when the detected temperature of the fixing rotating body pair is lower than the fixing temperature (set temperature).

  When the paper dust amount and the toner amount are ranked in the stain diagnosis table (see FIG. 7), the rotation direction and the rotation speed of the rotating brush 42 (the rotation speed ratio with respect to the soaking roller 41) based on the rotation setting table (see FIG. 10). ). In the second embodiment, since fine ranking is performed, it is not necessary to execute high-temperature idling in the forced cleaning mode after printing is completed. However, if the cumulative number of printed sheets exceeds a predetermined number (for example, about 3000), the forced cleaning mode may be executed after the printing is completed. The cleaning rotation control may be executed with only the rotation speed of the rotary brush 42 being variable, with the rotation directions in the vicinity of the nip portion of the soaking roller 41 and the rotary brush 42 being set to the forward direction.

  As described above, even when the control of the second embodiment is employed, the same effects as those of the first embodiment can be obtained.

  The present invention is not limited to the above-described embodiment, and can be embodied in various forms. For example, a printer has been described as an example of the image forming apparatus. However, the image forming apparatus is not limited thereto, and may be a copier, a facsimile, or a complex machine having these functions in combination. Moreover, when applying this invention, you may employ | adopt a resistance heating element and a halogen heater as another aspect of the heating part 35 other than induction heating. A soaking roller 41 and a rotating brush 42 may be disposed on the fixing roller 31 side. In addition, the configuration of each unit is not limited to the illustrated embodiment, and various modifications can be made without departing from the spirit of the present invention.

P Recording material S Conveying direction 1 Printer 5 Fixing device 28 Control unit 31 Fixing roller 32 Pressing roller 33 Fixing nip unit 35 Heating unit (magnetic flux generating unit)
37 fixing belt 41 soaking roller 42 rotating brush 47 brush motor 48 operation panel 49 photo sensor 50 cleaning blade body

Claims (9)

In an image forming apparatus provided with a fixing device that allows a recording material with an unfixed toner image to pass through a fixing nip formed by a pair of fixing rotators to fix the recording material.
A soaking rotator that contacts either one of the fixing rotator pair to equalize the temperature distribution in the sheet passing width direction, a cleaning rotator that contacts the soaking rotator and cleans it, and the soaking A paper dust amount detecting means for detecting the amount of paper dust transferred to the rotating body, and a rotation control means for controlling the rotation of the cleaning rotating body based on detection information of the paper dust amount detecting means,
Image forming apparatus. A toner amount detecting means for detecting the amount of toner transferred to the soaking rotator;
The rotation control unit controls rotation of the cleaning rotating body based on detection information of the toner amount detection unit in addition to detection information of the paper dust amount detection unit;
The image forming apparatus according to claim 1. The cleaning rotator is configured to be rotatable forward and backward.
The image forming apparatus according to claim 1. The rotational speed of the cleaning rotator is configured to be variable.
The image forming apparatus according to claim 1. The paper dust amount detection means detects the amount of paper dust transferred to the soaking rotator based on information on the paper type of the recording material to be used for printing.
The image forming apparatus according to claim 1. The paper dust amount detecting means detects the amount of paper dust transferred to the soaking rotator based on information on the number of sheets of recording material to be subjected to printing.
The image forming apparatus according to claim 1. The rotation control unit idles the fixing rotating body pair by setting the fixing temperature higher than usual after the end of printing or after executing a predetermined number of prints.
The image forming apparatus according to claim 1. The paper dust amount detecting means includes a photo sensor for detecting the amount of paper dust attached to a rotating member that conveys the recording material, and a cleaning blade body that is disposed on the outer peripheral side of the rotating member on the rotation downstream side of the photo sensor. With
The image forming apparatus according to claim 1. The toner amount detection means detects the amount of toner transferred to the soaking rotator based on information on a printing rate, a use environment, and a fixing temperature;
The image forming apparatus according to claim 2.

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