JP2003057985A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus preventing image staining caused by the back flow of adhesive toner and preventing abnormal sound or noise from a cleaning roller 14. SOLUTION: In this image forming apparatus having the cleaning roller 14 for removing the toner adhering to at least either of a pair of rotating bodies (fixing roller 10 and pressure roller 20) in a fixing device permanently fixing a toner image on the transfer material by heating and pressurizing by inserting transfer material on which an unifixed toner image is put in a fixing nip part between a pair of rotating bodies, the transfer material is made to pass through the fixing nip part by the fixed number of sheets, and then the rotating body is idly rotated at image formation performable temperature, and further cleaning paper is automatically made to pass through the fixing nip part, whereby the toner adhering to the roller 14 is recovered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus for forming an image by transferring the image onto a transfer material and fixing the image.

[0002]

2. Description of the Related Art A conventional image forming apparatus will be described with reference to the drawings. FIG. 9 is an illustration of a conventional fixing device. 2. Description of the Related Art Conventionally, image forming apparatuses such as a facsimile machine, a printer, and a copying machine that use an electrophotographic method are known. They are,
An electrostatic latent image is formed on the photosensitive drum as an image carrier by the exposing means, and the electrostatic latent image is developed with toner to form a toner image. The toner image on the photosensitive drum is transferred to a transfer material by a transfer member, and thereafter,
The toner image is fixed on the transferred transfer material by the action of pressure and heat by the fixing device.

A fixing device used in a general laser printer will be described with reference to FIG. In FIG. 9, the fixing roller 110 is configured such that, for example, a releasable resin layer 112 such as PFA or PTFE is provided on a core metal 111 such as aluminum or iron, and the inside is heated by a heater 113. . The temperature of the fixing roller 110 is determined by the temperature detecting element 130 that contacts the fixing roller 110.
The surface temperature of 110 is detected, and the temperature control circuit intermittently operates the heater 113 to control the surface temperature to a predetermined temperature.

On the other hand, the pressure roller 120 which is in pressure contact with the fixing roller 110 and rotates, for example, is made of an elastic material such as silicon rubber or silicon sponge having a heat resistance and a low hardness on a metal core metal 121 such as aluminum or iron. The layer 122 is provided, and the surface thereof is covered with a resin having high releasability such as PFA or PTFE.
It has a structure having 123.

Further, the transfer material T carrying the toner image t is
The fixing roller 110 and the pressure roller 120 are guided by the inlet guide 124.
The toner is guided to the fixing nip portion between and is heated and pressed to fix the toner. Generally, the inlet guide 124 is made of a resistance control material such as PBT (10E8 to 10E10Ω) or has a guide surface made of metal such as stainless steel, and the resistance control material is generally used as a contact point with the fixing frame. is there. This is because when the inlet guide is formed of an insulating material or the like, the guide surface is charged by sliding friction with the transfer material, which causes adverse effects such as toner scattering.

Further, in order to prevent wrinkles from occurring when the transfer material T passes through the fixing nip portion, the fixing roller 110 and the pressure roller 120 are provided with proper inverted crown shapes in the longitudinal direction, and fixing is performed by the inlet guide 124. It is common practice to optimize the position of entry into the nip. The transfer material T on which the toner image is fixed by being heated and pressed in the fixing nip portion is separated from either roller by the fixing roller separation claw 125 or the pressure roller separation claw 126, and guided to the discharge roller 128 by the discharge guide 127. Then, it is discharged to the outside of the device.

Here, calcium carbonate CaC is used as a filler.
When a large number of pages of transfer material containing 10% or more of O ₃ (hereinafter “calcium charcoal”) are passed through, the positively charged carbon charcoal powder has a negative potential on the surface of the fixing roller 110 to prevent offset. Adsorbs electrically. As a result, the fixing bias is canceled and the unfixed toner t on the transfer material T is removed.
Are electrically attracted to the surface of the fixing roller.

Further, due to the adhesion of calcium carbonate powder, the releasability of the surface of the fixing roller 110 is lowered, and the offset is deteriorated. The offset toner transfers from the surface of the fixing roller 110 to the surface of the pressure roller 120 and accumulates on the surface of the pressure roller 120 due to the difference in releasability in the transfer material conveyance interval. The toner attached or accumulated on the pressure roller in such a process returns to the back surface of the transfer material or returns to the fixing roller to cause surface contamination of the transfer material.

Therefore, conventionally, the cleaning roller 114 is brought into contact with the pressure roller 120 to collect the toner adhering to the surface of the pressure roller 120 to solve this problem.
As the cleaning roller 114, a roller made of metal such as aluminum or heat-resistant resin is generally used. This is to transfer the toner adhering to the surface of the pressure roller 120 to the cleaning roller by utilizing the fact that the releasability is inferior to the fluororesin of the surface layer of the pressure roller 120.

If the cleaning roller 114 is not used, there is also a method of cleaning the roller by passing the cleaning paper through the fixing nip portion when the pressure roller is contaminated to some extent. When the cleaning mode is entered, the cleaning paper is automatically passed to collect the toner adhering to the fixing roller 110 and the pressure roller 120 with paper or the like, and clean the rollers.
In general, the cleaning paper forms a solid black image and allows it to pass in order to improve the collection power of the toner adhering to the surface of the pressure roller 120.

[0011]

However, in the above-mentioned conventional example, there is a problem that the toner cleaned by the cleaning roller 114 flows back to the pressure roller 120 and the fixing roller 110 to cause image contamination of the transfer material T. . The backflow of the toner attached to the cleaning roller occurs when the temperature of the cleaning roller 114 is excessively increased.
For example, in order to improve the fixing property of thick paper, in a special mode in which the fixing temperature is set to a high temperature, when a special transfer material such as thick paper is continuously passed, the cleaning roller 114 is excessively heated to melt the toner. In the above case, the toner adhering to the cleaning roller is melted out, and a backflow occurs over the entire length of the roller.

When a small-sized transfer material such as LGL, B5, or envelope is continuously passed, the transfer material does not pass through the non-passage area of the pressure roller 120 from the fixing roller 110. Since it does not occur, the temperature rises above the passage area. At this time, the temperature of the non-passage area also rises with respect to the passage area of the cleaning roller 114 that contacts the pressure roller 120 having a heat gradient.

Therefore, the cleaning roller 114, which has passed the transfer material having the maximum passage width and uniformly collects the offset toner in the entire longitudinal direction, does not pass when a large amount of the transfer material having a small size is continuously passed. The toner in the area may be remelted and may flow back to the pressure roller 120 and further to the fixing roller 110. After that, when the large-sized transfer material is passed again, the backflow toner from the end portion of the cleaning roller 114 adheres to the transfer material to cause image contamination.

The cleaning roller 114 collects the offset toner transferred to the pressure roller 120.
This toner gradually adheres to the cleaning roller 114,
Build up. Therefore, when several hundred thousand sheets are passed, the diameter of the cleaning roller 114, which is thick due to toner adhesion, becomes too large for the space of the fixing device frame, and when the cleaning roller 114 comes into contact with the fixing device frame, an abnormal noise or noise is generated. Noise may occur.

Further, when the toner is accumulated on the cleaning roller 114, the cleaning roller 114 cannot be rotated by being driven by the pressure roller 120, and as a result, the load due to the increase in torque during driving causes The gear of the fixing roller 110 was sometimes broken.

Therefore, an object of the present invention is to provide an image forming apparatus which prevents image contamination due to back flow of adhered toner and prevents abnormal noise and noise from the cleaning roller.

[0017]

A typical constitution of the present invention for achieving the above object is to insert a transfer material carrying an unfixed toner image in a fixing nip portion between a pair of rotating members, In an image forming apparatus having a cleaning rotator that cleans toner adhered to at least one rotator of a fixing device that permanently fixes a toner image on a transfer material by heating and pressurization, a fixed number of transfer materials are provided in the fixing nip portion. After passing, the idle rotation of the rotating body is performed at a temperature at which an image is formed, and a cleaning material is automatically passed through the fixing nip portion to collect the toner adhering to the cleaning rotating body. And

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) In the first embodiment, after a certain number of small-sized transfer materials are continuously passed through, the rollers are idled by the print temperature control so that the cleaning roller is not rotated. An example will be shown in which the adhered toner is allowed to flow backward, and then the cleaning paper as a cleaning material is automatically passed through the fixing nip portion to recover the countercurrent toner. FIG. 1 is an explanatory view of the image forming apparatus, and FIG. 2 is a sectional view of the fixing device. First, the image forming apparatus will be described, and then the fixing apparatus will be described.

As shown in FIG. 1, the image forming apparatus includes a photosensitive drum 1, an exposure device 2, a developing device 3, a transfer member 4, a cleaning device 5, a charging member 6, a fixing device 7, and a transfer material to be supplied. A feeding cassette C, a feeding device 8, a transfer material conveyance path P, and a laser beam L emitted from the exposure device 2.

The exposure device 2 turns on / off the laser light L according to image information to irradiate the surface of the photosensitive drum 1 charged to a desired potential by the charging member 6 to remove the electric charge. To form an electrostatic latent image on the photosensitive drum 1.

The developing device 3 comprises a developer (hereinafter referred to as toner), a developing container, and a developing sleeve 9.
Toner is supplied from the developing sleeve 9 in accordance with the electrostatic latent image, and a toner image is formed on the photosensitive drum 1. Then, the toner image on the photosensitive drum 1 is transferred onto the surface of the transfer material by the transfer member 4.

The unfixed toner image on the transfer material is permanently fixed on the transfer material by being heated and pressed by the fixing device 7, and is discharged from the image forming apparatus. On the other hand, the cleaning device 5 removes toner, paper dust and the like remaining on the photosensitive drum 1 during transfer.

Further, this image forming apparatus has a special transfer material mode, a switch for setting the special transfer material is provided on an operator operation panel (not shown), and the user selects the mode to transfer the transfer material. Depending on the thickness, it is possible to partially change the process conditions such as the transfer material conveyance speed and the fixing temperature.

As shown in FIG. 2, the fixing device 7 has an A3 size.
(297 mm) This is an example of a central reference in which a transfer material having a maximum passable size is conveyed using the passage center of the apparatus as a reference. As the heater 13, a heater that outputs a rated output of 800 W when inputting 120 V is used. The light also has a symmetrical distribution with respect to the passage standard.

First, the fixing device 7 has a fixing roller 10 and a pressure roller 20 as a rotating body. The fixing roller 10 has a core metal 11 of aluminum and a diameter of 40 mm and a thickness of 3.0 m.
m roller, and the release layer 12 of PFA is coated on the surface layer. The pressure roller 20 has a silicon sponge elastic layer 22 on a stainless steel core 21 and a PFA release layer 23 on the surface layer.
It has a diameter of 30 mm and a product hardness of 50 °.
A nip width of 5.0 mm can be created between the fixing roller 10 and the fixing roller 10 by applying a pressing force of 00N.

Further, the thermistor 30 as a temperature detecting element
By arranging at the substantially central portion of the fixing roller 10, the surface temperature of the fixing roller 10 can be accurately adjusted, and stable fixing performance can be secured. It should be noted that with this configuration, it is possible to print 30 sheets / minute with A4 lateral feed.

The cleaning roller 14 as a cleaning rotary member is in contact with the pressure roller 20, and is configured to rotate following the pressure roller 20. The first condition is that the surface of the cleaning roller 14 is inferior in releasability to the surface of the pressure roller 20, but since the cleaning property of the toner is improved when the surface of the cleaning roller 14 is easily heated, the material is usually aluminum having a small heat capacity. Metals such as are used.

However, as described above, when a large amount of small-sized transfer material is continuously passed, back flow of the adhered toner from the end portion of the cleaning roller 14 occurs. In such a backflow, the surface temperature of the end portion of the cleaning roller is about 1 to the melting point of the toner.
When the temperature exceeds 50 ° C., the toner adhering to the cleaning roller 14 melts and is generated.

FIG. 3 shows changes in the surface temperature of the end portion of the cleaning roller 14 when 250 small-sized transfer materials are continuously passed. As can be seen from FIG. 3, the surface temperature of the end portion of the cleaning roller 14 was about 100 ° C. at the start of printing, and the melting point of the toner reached 150 ° C. at the time of continuously passing about 220 sheets. The toner that has been started begins to flow back to the pressure roller 20 and the fixing roller 10.

Therefore, it is highly possible that a backflow occurs at the end of the roller after 220 or more small-sized transfer materials are continuously passed. Such backflow toner becomes contaminated and becomes visible when the large-sized transfer material is passed through the fixing nip portion next time.

In the present embodiment, after 220 or more small-sized transfer materials such as LGL, B5, and envelopes are continuously passed, after the job is completed, idle rotation is performed for 60 seconds at a print temperature control of 190 ° C. to perform automatic operation. The cleaning paper.

FIG. 4 shows a control sequence of the first embodiment. After finishing the job of continuously passing 220 sheets or more of small-sized transfer material, the print temperature control of 190 ° C. is maintained and t =
The idle rotation is performed for 60 seconds, and the reverse flow is further advanced. At this time, if the apparatus has the special transfer material mode, the idle rotation time t can be shortened by further promoting the backward flow by setting the mode in which the fixing temperature is higher and performing the idle rotation. .

In this way, after as much toner as possible adheres to the end portion of the cleaning roller 14 which may cause image contamination due to backflow, and also backflows to the upstream surface of the fixing roller 10 as much as possible, the cleaning is automatically performed. The toner is collected by passing the paper.

The cleaning paper will be described below. When the feeding cassette C contains large-sized transfer materials such as LTR, A4, and A3, these transfer materials are automatically passed through the fixing nip portion. If the feeding cassette C
If there is no large-sized transfer material in, the operator operation panel (not shown) notifies the user that the roller is to be cleaned, and the large-sized transfer material is set in the manual feed tray. In the case of an apparatus that can only print on one side, the transfer material with solid black (hatched portion in the figure) printed on one side as shown in FIG. 5A is passed to mainly remove toner stains on the surface of the fixing roller 10. However, the toner collecting power on the surface of the pressure roller 20 is slightly lowered.

If the device has an automatic duplex unit,
By printing and passing solid black on both sides, it is possible to remove toner stains on both the fixing roller 10 and the pressure roller 20. If the margin of the front end of the cleaning paper is small, the cleaning paper may be attracted to the fixing roller to cause roller wrapping due to improper separation. Therefore, it is desirable to provide a margin of L = 30 mm or more at the front end.

Further, in order to save toner, FIG.
As shown in (b), one rotation of the fixing roller 10 a = 125 m
Solid black may be printed in the range of m. In addition, FIG.
By printing a parallelogram as shown in the above, the entire transfer material is not adsorbed on the roller surface at the same time in the roller longitudinal direction, and the separation of the transfer material due to stiffness is promoted.
Rolling of the cleaning paper as described above can be prevented.

Further, the backflow of the toner attached to the cleaning paper due to the continuous passage of the small-sized transfer material occurs only at the end portion where the roller surface temperature rises excessively, so that FIG.
As shown in, both ends of the cleaning paper b = 40 mm
Solid black may be printed in the range of and passed.

Also in this case, it is desirable to provide a margin of L = 30 mm or more, and as shown in FIG. 6B, printing is performed in the range of a = 125 mm for one rotation of the fixing roller 10,
A parallelogram may be printed as shown in FIG.
It should be noted that the larger the printing area of the cleaning paper and the number of passing sheets, the more backflow toner can be collected. In this way, the toner that flows back to the fixing roller 10 and the pressure roller 20 can be collected by passing the cleaning paper on which the transfer material is entirely or partially printed with solid black.

As described above, the transfer material of small size is
After 20 sheets or more have been continuously passed, idle temperature rotation is performed for 60 seconds in print temperature control so that the adhering toner is made to flow backward from the cleaning roller, and then automatically passed through the cleaning paper to collect the backward flowing toner, and then the large size toner is It is possible to prevent the occurrence of dirt at the edge of the image due to the backflow toner when passing the transfer material, and it is possible to prevent abnormal noise and noise from the cleaning roller.

(Second Embodiment) In the second embodiment, when a certain number of sheets are continuously passed in the special transfer material mode, the printing operation is interrupted and idling is performed by the print temperature control, and the toner adhered from the cleaning roller is removed. An example of a case in which the backflowing toner is automatically passed through the cleaning paper and the backflowing toner is collected will be described. In this embodiment, the same components as those in the above-described embodiment are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 7 shows the sequence of this embodiment. In the present embodiment, in the special transfer material mode such as thick paper, when the number of continuously passing thick paper reaches 180 sheets, the printing operation is stopped and the print temperature adjustment set to 195 ° C. in the special transfer material mode is performed. = 40 sec idle rotation is performed. Due to this idle rotation, the toner attached to the cleaning roller flows back to the pressure roller 20 and the fixing roller 10 over the entire area in the longitudinal direction.

Thereafter, the cleaning paper is automatically passed through the fixing nip portion to collect the backflow toner and clean the pressure roller 20 and the fixing roller 10.
The cleaning paper is the same as in the first embodiment, and the cleaning paper shown in FIGS. 5A to 5C may be passed. As a result, it is possible to prevent image smearing due to the backflow toner over the entire area in the longitudinal direction, and to suppress the backflow of toner adhering to the cleaning roller even after that.

If the job is to pass 180 sheets or more,
After executing the above sequence, restart the job. After that, the printing operation is stopped every time 180 sheets are passed, and the above sequence is repeated until the job is completed.

As described above, the print toner in the special transfer material mode is idly rotated for 40 seconds to reverse the flow of the adhered toner from the cleaning roller 14 and then automatically pass through the cleaning paper to collect the reverse flow toner. By doing so, it is possible to prevent image stains due to back flow of adhered toner on the entire length of the cleaning roller 14.

(Third Embodiment) In the third embodiment, when the number of passing sheets exceeds a certain number, idle rotation is performed by adjusting the print temperature to reverse the flow of the adhered toner from the cleaning roller 14, and then the cleaning paper is automatically removed. An example of collecting backflow toner by passing it through the fixing nip portion will be described. In this embodiment, the same configuration as that of the above-described embodiment is
The same reference numerals are given and the description is omitted.

FIG. 8 shows the sequence of this embodiment. In the present embodiment, the number of passing sheets after replacement of the fixing unit has reached 200,000 sheets, and after the job is completed, idle rotation is performed at a print temperature adjustment of 190 ° C. for an idle rotation time t = 90 sec, and the cleaning roller 14 is forced. The adhered toner is caused to flow back from. In this case, a large amount of toner is expected to adhere to the cleaning roller 14, so the idle rotation time t should be as long as possible.

Further, as in the first embodiment, in the case of the apparatus having the special transfer material mode, the progress of the backflow is further promoted by setting the mode in which the fixing temperature is higher and performing the idling. The idle rotation time t can be shortened.

In this way, as much toner as possible is made to flow back from the cleaning roller 14, and then the toner is collected by the cleaning paper shown in FIGS. 5A to 5C as in the first embodiment. However, at this time, it is impossible to completely flow back and collect all the toner adhering to the cleaning roller, and thereafter, the same cleaning sequence is performed every 100,000 sheets. This allows
It is possible to prevent adverse effects such as abnormal noise and noise when the cleaning roller comes into contact with the fixing device frame and damage to the gear due to being too thick.

As described above, after passing 200,000 sheets, after the job is completed, the print temperature is controlled to idle for 90 seconds so that the adhering toner flows back from the cleaning roller 14 and then automatically passes through the cleaning paper. To collect backflow toner. Also, by executing the same sequence every time 100,000 sheets are passed, abnormal noise and noise at the time of contact with the fixing device frame due to excessive adhesion of toner to the cleaning roller 14 and damage to gears are prevented. Can be prevented.

Whether or not the cleaning means described above is executed can be switched, and the user can arbitrarily select it. Further, the first to third embodiments may be used in combination.

(Other Embodiments) In the above-described embodiments, the printer has been described as an example of the image forming apparatus, but the image forming apparatus is not limited to this, and may be a facsimile machine or a copying machine.

In the above-described embodiment, the cleaning material is paper, but the material is not limited to this, and a resin material may be used.

[0053]

As described above, in the present invention, after a certain number of transfer materials have passed through the fixing nip portion, a pair of rotary members are idled at a temperature for image formation, and a cleaning material is further added. In order to collect the toner adhering to the cleaning rotary member by automatically passing through the fixing nip portion, the adhered toner on the cleaning roller flows back to the fixing roller via the pressure roller and is fixed again on the transfer material. It is possible to prevent the image from being stained and to prevent abnormal noise and noise from the cleaning roller.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an image forming apparatus.

FIG. 2 is a cross-sectional view of a fixing device.

FIG. 3 is a diagram showing a temperature change at an end portion of a cleaning roller.

FIG. 4 is a diagram showing a control sequence of the first embodiment.

FIG. 5 is a diagram showing a toner printing area of cleaning paper.

FIG. 6 is a diagram showing a print area of the cleaning paper according to the first embodiment.

FIG. 7 is a diagram showing a control sequence of the second embodiment.

FIG. 8 is a diagram showing a control sequence of a third embodiment.

FIG. 9 is a sectional view of a conventional fixing device.

[Explanation of symbols]

C ... Feed cassette L ... Laser light P ... Transport path T ... Transfer material t ... toner image 1 ... Photosensitive drum 2 ... Exposure device 3 ... Developer 4 ... Transfer member 5 ... Cleaning device 6 ... Charging member 7 ... Fixing device 8 ... Feeding device 9 ... Development sleeve 10… Fusing roller 11… Core metal 12… Release layer 13… Heater 14… Cleaning roller 20… Pressure roller 21… Stainless steel core 22 ... Elastic layer 23… Release layer 24… Entrance Guide 25… Fixing roller separation claw 26… Pressure roller separation claw 27… Discharge guide 28… Ejection roller 30… Thermistor

Continued front page    F term (reference) 2H027 DA12 DA46 DC10 EA12 EC02                       ED25 EE01 EF09 FA05 FA30                       HB02 HB06 HB19                 2H033 AA08 AA23 AA40 AA45 BA30                       BA48 BA49 BA57 BA58 BB01                       BB28 CA07 CA17 CA19 CA20                       CA30 CA40

Claims (7)

[Claims] 1. A fixing device for inserting a transfer material carrying an unfixed toner image into a fixing nip portion between a pair of rotating bodies and permanently fixing the toner image on the transfer material by heating and pressing. In an image forming apparatus having a cleaning rotator that cleans toner adhered to a rotator, a certain number of transfer materials are passed through the fixing nip portion, and then the rotator is idled at a temperature at which image formation is performed.
Further, the image forming apparatus is characterized in that a cleaning material is automatically passed through the fixing nip portion to collect the toner adhering to the cleaning rotary member. 2. A fixing device which inserts a transfer material carrying an unfixed toner image into a fixing nip portion between a pair of rotating bodies, and permanently fixes the toner image on the transfer material by heating and pressing. In an image forming apparatus having a cleaning rotator for cleaning toner attached to a rotator, the rotator idles at a temperature at which an image is formed every time a certain number of transfer materials are passed through the fixing nip portion. Further, the image forming apparatus is characterized in that a cleaning material is automatically passed through the fixing nip portion to collect the toner adhering to the cleaning rotary member. 3. The image forming apparatus according to claim 2, wherein when the second and subsequent idle rotations are performed at a temperature at which the image is formed, the cleaning material to the fixing nip portion is more than when the first rotation is performed. An image forming apparatus characterized in that the number of sheets passing through is set to be small. 4. A fixing device for inserting a transfer material carrying an unfixed toner image into a fixing nip portion between a pair of rotating bodies and permanently fixing the toner image on the transfer material by heating and pressing. In an image forming apparatus having a cleaning rotator that cleans toner adhered to a rotator, a transfer material having a width smaller than a maximum passage width of the transfer material in the image forming apparatus is continuously passed through a certain number or more through the fixing nip portion. After that, the rotating member is idled at a temperature at which an image is formed, and a cleaning material is automatically passed through the fixing nip portion to collect the toner adhering to the cleaning rotating member. Image forming apparatus. 5. A fixing device for inserting a transfer material carrying an unfixed toner image into a fixing nip portion between a pair of rotating bodies and permanently fixing the toner image on the transfer material by heating and pressing. In an image forming apparatus having a cleaning rotator that cleans toner adhered to the rotator, after a certain number of transfer materials have been continuously passed through the fixing nip portion, the image forming operation is stopped and the temperature is changed to the temperature at which the image is formed. The image forming apparatus is characterized in that the rotating body is idled and the cleaning material is automatically passed through the fixing nip portion to collect the toner adhering to the cleaning rotating body. 6. The image forming apparatus according to claim 1, wherein when the fixing device has a plurality of modes in which heating conditions can be changed, the temperature for fixing is set to the highest mode. An image forming apparatus, wherein the rotating body is idled at a temperature at which an image is formed. 7. A fixing device for inserting a transfer material carrying an unfixed toner image into a fixing nip portion between a pair of rotating bodies and permanently fixing the toner image on the transfer material by heating and pressing. In an image forming apparatus having a cleaning rotator for cleaning toner attached to a rotator, the fixing device collects the toner attached to the cleaning rotator by the cleaning method according to any one of claims 1 to 6, and An image forming apparatus capable of switching whether or not to execute a cleaning method.