JP7483831B1 - Image forming device - Google Patents

Abstract

[Problem] To prevent oil applied to the inner peripheral surface of a fixing belt from leaking out to the outside of the fixing belt. [Solution] A fixing device that fixes a toner image on a recording material, the fixing device has a fixing belt, a polishing member, and an oil application member that applies oil to the inner peripheral surface of the fixing belt, and when the number of sheets of recording material printed after the oil application member is replaced is less than a predetermined number, the rotation speed of the fixing belt when the polishing member polishes the fixing belt is slower than the rotation speed of the fixing belt when the polishing member polishes the fixing belt when the number of sheets printed is equal to or greater than the predetermined number. [Selected Figure] Figure 2

Description

The present invention relates to an image forming apparatus equipped with a fixing device that fixes a toner image onto a recording material.

Image forming devices are widely used in which a toner image carried on a photosensitive drum or intermediate transfer belt is transferred to a recording material, and the recording material with the transferred toner image is heated and pressurized by a fixing device to fix the image to the recording material. The fixing device heats the recording material by sandwiching and transporting it between multiple heating rotors, thereby fixing the toner image to the recording material.

As the heating process of the recording material accumulates in the fixing device, friction scratches caused by the recording material occur on the surface of the heating rotor due to the pressure applied to transport the paper. When the toner image is softened by heating on the heating rotor with the friction scratches and fixed to the recording material, the surface condition of the heating rotor is transferred to the toner image. As a result, there is a possibility that the output recording material will have effects such as uneven gloss.

In order to improve the gloss unevenness, Patent Document 1 proposes a fixing device equipped with a pair of rotating bodies and a rubbing member that can be attached to and detached from at least one of the pair of rotating bodies. In this device, the rubbing member is caused to rub against the rotating bodies for a certain period of time prior to the heating operation of the pair of rotating bodies, depending on the basis weight of the recording material, to smooth the surface of the heated rotating body.

Furthermore, in the fixing device of Patent Document 2, a lubricant is applied to the sliding parts to suppress wear on the inner surface of the belt that comes into sliding contact with the heating rotor and each sliding part.

JP 2013-54108 A Patent Publication No. 2021-140135

In fixing devices that apply oil to the inner surface of the fixing belt, the lubricant can leak out onto the outside of the fixing belt. In particular, in fixing devices that use a fixing pad, oil is likely to accumulate on the upstream side of the fixing pad in the conveying direction of the fixing belt. When the fixing belt and pressure roller separate, this accumulated oil can travel along the belt detection unit that comes into contact with the end of the fixing belt and reach the outer surface side of the fixing belt. The oil that reaches the outer surface side of the fixing belt adheres to the toner image and causes image defects.

The image forming apparatus of the present invention aims to suppress the occurrence of image defects caused by oil in a fixing device in which oil is applied to the inner surface of the fixing belt.

a fixing belt that is endless and applies heat to a recording material; a fixing pad that is arranged on the inner peripheral surface of the fixing belt; a pressure rotating body that contacts the fixing belt; the pressure rotating body forms a nip portion with the fixing belt, and the toner image is fixed to the recording material by applying heat and pressure to the recording material carrying a toner image at the nip portion; a rotation control unit that controls the rotation speed of the fixing belt; an oil application member that applies oil to the inner peripheral surface of the fixing belt; a polishing member that contacts the outer peripheral surface of the fixing belt and polishes the outer peripheral surface of the fixing belt; and the polishing member is capable of contacting and separating from the fixing belt, An image forming apparatus characterized in that it includes a counter that counts the number of sheets of recording material that have been printed, and when the number of sheets of recording material counted by the counter after the oil application member is replaced is less than a predetermined value and the polishing member polishes the fixing belt, the rotation control unit controls the rotation speed of the fixing belt to a first speed, and when the number of sheets of recording material counted by the counter after the oil application member is replaced is equal to or greater than the predetermined value and the polishing member polishes the fixing belt, the rotation control unit controls the rotation speed of the fixing belt to a second speed that is faster than the first speed.

The image forming device of the present invention can prevent the lubricant applied to the inner surface of the belt from leaking during polishing by the polishing member.

FIG. 1 is a schematic diagram of an image forming apparatus. FIG. 2 is a cross-sectional view of the fixing device according to the embodiment. FIG. 2 is a diagram illustrating a configuration of a polishing member. FIG. 2 is a control block diagram of the image forming apparatus. FIG. 2 is a diagram illustrating a surface state of a fixing roller. 1 is a table showing refresh control conditions. FIG. 2 is a diagram showing the inner surface of a fixing belt. 6 is a diagram showing the relationship between the amount of oil supplied and the rotation speed of a fixing belt. 13 is a flowchart of refresh control execution conditions. 13 is a flowchart of a refresh control operation setting;

<Image forming apparatus>
The schematic configuration of an image forming apparatus according to this embodiment will be described with reference to FIG.

Figure 1 shows a full-color image forming apparatus according to this embodiment. The image forming apparatus 1 comprises an image reading unit 2 and an image forming apparatus main body 3. The image reading unit 2 reads an original placed on a platen glass 21. Light emitted from a light source 22 is reflected by the original and an image is formed on a CCD sensor 24 via an optical system component 23 such as a lens. This optical system unit scans in the direction of the arrow to convert the original into an electric signal data string for each line. The image signal obtained by the CCD sensor 24 is sent to the image forming apparatus main body 3, where the control unit 30 performs image processing in accordance with each image forming unit described later. The control unit 30 also receives external inputs as image signals from an external host device such as a print server.

The image forming device main body 3 has multiple image forming units Pa, Pb, Pc, and Pd, and each image forming unit forms an image based on the image signal described above. That is, the image signal is converted into a laser beam that is PWM (pulse width modulation) controlled by the control unit 30. In FIG. 1, 31 is a polygon scanner serving as an exposure device, which scans with a laser beam according to the image signal. The laser beam is then irradiated onto the photosensitive drums 200a to 200d serving as image carriers for each image forming unit Pa to Pd.

Note that Pa is a yellow (Y) image forming section, Pb is a magenta (M) image forming section, Pc is a cyan (C) image forming section, and Pd is a black (Bk) image forming section, which each form an image of the corresponding color. Since the image forming sections Pa to Pd are substantially the same, the Y image forming section Pa will be described in detail below, and the description of the other image forming sections will be omitted. In the Y image forming section Pa, 200a is a photosensitive drum, and as described below, a toner image is formed on the surface based on an image signal.

201a is a primary charger that charges the surface of the photosensitive drum 200a to a specified potential to prepare for the formation of an electrostatic latent image. A laser beam from the polygon scanner 31 forms an electrostatic latent image on the surface of the photosensitive drum 200a, which has been charged to a specified potential. 202a is a developer that develops the electrostatic latent image on the photosensitive drum 200a to form a toner image. 203a is a transfer roller that discharges from the back of the intermediate transfer belt 204 and applies a primary transfer bias of opposite polarity to the toner, transferring the toner image on the photosensitive drum 200a onto the intermediate transfer belt 204. After transfer, the surface of the photosensitive drum 200a is cleaned by a cleaner 207a.

The toner image on the intermediate transfer belt 204 is conveyed to the next image forming section, where the toner images of each color formed in each image forming section are transferred in the order of Y, M, C, and Bk, forming a four-color image on the surface. The toner image that has passed through the Bk image forming section is secondarily transferred to the paper P in the secondary transfer section consisting of the secondary transfer roller pair 205, 206 by applying a secondary transfer electric field of the opposite polarity to the toner image on the intermediate transfer belt 204. The fed paper waits in the registration section 208, and then the timing is controlled to align the position of the toner image on the intermediate transfer belt with the paper, and the paper is conveyed from the registration section. The toner image on the paper is then fixed to the paper by the fixing device F, which serves as an image heating device. After passing through the fixing device, the paper is discharged outside the machine. In the case of double-sided paper feeding, when the transfer and fixing of the toner on the first side (first side) of the image formation is completed, the paper passes through a reversing section provided inside the image forming device after fixing, and the front and back of the paper are reversed. The toner for the second side of the image is then transferred and fixed, and the paper is ejected from the machine and stacked on the paper ejection tray 7.

Next, the configuration of the fixing device F in this embodiment will be described with reference to FIG.

<Fixing Device>
2 shows a schematic diagram of the overall configuration of a belt heating fixing device F according to this embodiment. The fixing device F has a fixing belt (hereinafter, belt) 310 as an endless rotatable heating rotator, and a pressure pad (hereinafter, pad) 320 as a fixing member. It further has a heating unit 300 including a heating roller 340 and a steering roller 350, and a pressure roller 330 as a pressure rotator that faces the belt and forms a nip N together with the belt.

The belt 310 has thermal conductivity, heat resistance, etc., and is a thin-walled cylindrical shape. The belt 310 is stretched by the pad 320, the heating roller 340, and the steering roller 350.

The pad 320 is pressed against the pressure roller 330 with the belt 310 sandwiched between them. The material of the pad 320 is LCP (liquid crystal polymer) resin. A lubricating sheet 370 is interposed between the pad 320 and the belt 310. The lubricating sheet 370 is a PI (polyimide) sheet coated with PTFE (polytetrafluoroethylene) and has a thickness of 100 μm. The PI sheet has 100 μm protrusions at 1 mm intervals, which reduces the contact area with the belt 310 and reduces the sliding resistance. On the inner surface of the belt 310, an oil application roller 393 is arranged, which is formed by impregnating a roll-shaped member wrapped with a 100 μm thick nonwoven fabric (felt) with silicone oil. The oil application roller 393 applies a lubricant to the inner surface of the belt 310, so that the belt 310 slides smoothly against the pad 320. Silicone oil is used as the lubricant. The oil application roller 393 is not limited to a roller. It may be any oil application member. For example, the oil application member may be a non-rotating member that is fixed to the inner surface of the fixing belt 310.

The heating roller 340 is a stainless steel pipe with a thickness of 1 mm, and a halogen heater (not shown) is disposed inside the pipe, which is capable of heating the heating roller 340. The belt 310 is heated by the heating roller 340, and is controlled to a predetermined target temperature according to the paper type based on temperature detection by the thermistor 392. The thermistor 392 is placed in contact with the heating roller 340.

The steering roller 350 has a center of rotation at one end or near the center, and is rotated by the steering control unit 351 relative to the belt 310 to generate a tension difference between the front and rear, thereby controlling the position of the belt 310 in the main scanning direction.

A belt position detection unit 394 is provided near the belt 310 as a contact part, and the belt position detection unit detects the position in the main scanning direction, and the main scanning direction position is controlled according to the sensor detection result.

The steering roller 350 is biased by a spring supported by the frame of the heating unit 300, and also serves as a tension roller that applies a predetermined tension to the belt 310.

The pressure roller 330 is a roller with an elastic layer formed on the outer circumference of the shaft, and a release layer formed on the outer circumference of the elastic layer. The shaft is made of stainless steel, the elastic layer is 5 mm thick and made of conductive silicone rubber, and the release layer is 50 μm thick and uses PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin) as a fluororesin. The pressure roller 330 is supported by the fixing frame 380 of the fixing device F, and a gear is fixed to one end of the pressure roller 330, which is connected to a drive source (not shown) via the gear and rotated.

In the nip portion N formed between the belt 310 and the pressure roller 330, the recording material P carrying the toner image is sandwiched and the toner image is heated while being transported. In this way, the fixing device F fixes the toner image to the recording material P while sandwiching and transporting the recording material P. Therefore, it is necessary to achieve both the function of applying heat and pressure and the function of transporting the recording material P.

The fixing frame 380 is provided with a heating unit positioning portion 381, a pressure frame 383, and a pressure spring 384. The stay 360 of the heating unit 300 is inserted into the heating unit positioning portion 381, and the stay 360 is fixed to the heating unit positioning portion 381 by a fixing means (not shown).

After the stay 360 is fixed, the pressure roller contact/separation mechanism 385, which is driven by a drive source and a cam (not shown), moves the pressure frame 383, causing the pressure roller 330 to be pressed against the pad 320 via the belt 310.

<Refresh roller>
In this embodiment, a refresh roller is used as the polishing member. The refresh roller, which is the polishing member, contacts the outer peripheral surface of the belt 310. The polishing member in this embodiment has a rotatable roller shape, and improves polishing performance by rotating in the opposite direction to the rotation direction of the belt 310. As shown in FIG. 2, the refresh roller 390 and the fixing belt refresh roller rocking mechanism 395 are provided on the belt 310. The pressure refresh roller 391 and the pressure roller refresh roller rocking mechanism 396 provided on the pressure roller 330 have the same mechanism. Therefore, the following will explain the refresh roller 390 and the rocking mechanism, and will not repeat the explanation of the pressure refresh roller 391 and the rocking mechanism.

Figure 3 is an explanatory diagram of the configuration of the refresh roller. The refresh roller 390 is a core metal 390a made of SUS304 (stainless steel) with an outer diameter of 12 mm, on which a sliding layer (surface layer) 390c is provided, which is formed by densely adhering abrasive grains, via an adhesive layer (intermediate layer) 390b. The refresh roller 390 is biased toward the heating roller 340 by pressure springs (not shown) at both ends of the core metal 390a in the direction of the rotation axis.

The thickness of the rubbing layer 390c is 5 μm or more and 20 μm or less. The abrasive grains that can be used are aluminum oxide, aluminum hydroxide oxide, silicon oxide, cerium oxide, titanium oxide, zirconia, lithium silicate, silicon nitride, silicon carbide, iron oxide, chromium oxide, antimony oxide, diamond, and mixtures thereof. Here, aluminum oxide-based (also called alumina, alundum, or molandum) abrasive grains with a grain size of 5 μm or more and 10 μm or less are used. Aluminum oxide-based abrasive grains are the most widely used abrasive grains, and are sufficiently hard compared to the release layer of the fixing belt 310 suspended on the heating roller 340, inexpensive, and have excellent cutting properties due to their acute angle shape. It has been confirmed that the refreshing roller 390 configured in this way achieves both the refreshing effect of the surface of the fixing belt 310 and the surface properties of the fixed image after refreshing.

As shown in FIG. 2, the fixing belt refresh roller rocking mechanism 395 brings the refresh roller 390 into contact with and away from the belt 310. The refresh roller 390 is driven by the rocking mechanism and contacts the belt 310 with a predetermined pressure due to the biasing force of a spring, forming a rubbing nip (not shown) with a predetermined width in the rotational direction. The refresh roller 390 is driven to rotate, and since there is a difference in peripheral speed between the rotational speed of the belt 310 and the refresh roller 390, the refresh roller 390 rubs against the belt 310 at the rubbing nip. In this way, the structure is capable of contact and separation.

<Control block of image forming apparatus>
10 shows a control block diagram of the image forming apparatus 1 according to this embodiment. The control unit 30 has a CPU 400 which performs basic control of the image forming apparatus 1. It also has a ROM 401 in which a control program and an application program are stored, and a RAM 402 which functions as a work area for executing the processing of the control program. It also has a timer 403 which can generate periodic time intervals for control and measure the elapsed time between two points, and an EEPROM 404 which retains data even when the power is turned off.

The control unit 30 includes a fixing drive motor 301 as a rotation control unit that drives the rotation sources including the pressure roller 330 and the heating roller 340 of the fixing device F as drive sources. It also includes a steering control unit 351 for rotating the steering roller 350, and a pressure roller contact and separation mechanism 385 for contacting and separating the fixing belt 310 and the pressure roller 330.

The rotation control unit 301 controls the rotation speed of the fixing belt. Specifically, it controls the rotation speed of the pressure roller 330 and the heating roller 340, thereby controlling the rotation speed of the fixing belt 310, which rotates in conjunction with them.

The control unit 30 is equipped with a thermistor 392 that is in contact with the heating roller 340 to measure the temperature, and a belt position detection unit 394 that detects the widthwise position of the belt 310 on the tension roller 350, and each is controlled based on a control signal.

In addition, each time a recording material passes through the fixing device F, a count is performed by the control program according to various information about the recording material, and the count value is recorded in the EEPROM 404.

<Refresh mode overview>
The refreshing roller 390 and the pressure refreshing roller 391 serving as polishing members can oscillate independently of each other. Therefore, the refreshing roller 390 and the pressure refreshing roller 391 individually come into contact with and separate from the belt 310 and the pressure roller 330. The control unit 30 operates the fixing belt refreshing roller oscillating mechanism 395 and the pressure roller refreshing roller oscillating mechanism 396 at appropriate timing to control the start and end times of the fixing belt refreshing mode and the pressure roller refreshing mode.

The control unit 30 controls the fixing belt refresh mode based on the count value of the fixing belt refresh counter, and the pressure roller refresh mode based on the count values of the pressure roller paper passing counter and surface property counter. Each count value is calculated according to the size, type, number of sheets passed through the fixing device F, and fixing temperature.

If the calculated count value meets the conditions described below, the refresh mode is activated at a specified timing.

By executing the fixing belt refresh mode, the refresh roller 390 is brought into contact with the belt 310, restoring the surface condition of the belt 310. Also, by executing the pressure roller refresh mode, the pressure refresh roller 391 is brought into contact with the pressure roller 330, restoring the surface condition of the pressure roller 330. When each of the above refresh modes is executed, the belt 310 and the pressure roller 330 are separated, and paper passage through the fixing device F is temporarily stopped.

<Changes in surface condition of fixing belt and pressure roller>
Changes in the surface conditions of the fixing belt and pressure roller will be described with reference to Fig. 5. Fig. 5 is a view of the fixing device shown in Fig. 2, viewed from downstream in the paper feed direction.

As the recording material P accumulates as it passes through the fixing device F, surface roughness of different degrees occurs in the paper passing and non-paper passing areas of the belt 310 and pressure roller 330.

Differences in the surface conditions of the belt 310 and pressure roller 330 between the paper passing areas and non-paper passing areas cause uneven gloss in the output image. When an unfixed toner image is fixed to the recording material P, the fixing device F applies pressure and heat to the recording material P. At this time, minute changes in the surface conditions of the belt 310 and pressure roller 330 are transferred to the surface of the fixed image. Differences in the surface conditions of the fixed image occur in response to the differences on the belt 310 and pressure roller 330, causing uneven gloss in the fixed image.

Therefore, in this embodiment, the surface condition of the belt 310 and pressure roller 330 that has become rough due to the above is rubbed by the refreshing rollers 390 and 391. As a result, the difference in the surface condition of the belt 310 and pressure roller 330 is made uniform by the surface shape of the refreshing rollers 390 and 391, improving gloss unevenness.

<Refresh mode execution timing and execution time>
FIG. 6 is a diagram showing the conditions for executing the refresh mode.

In this embodiment, we will not explain the pressure roller refresh control because it is the control for fixing belt refresh.

In the fixing belt refresh control, a count value is accumulated in the fixing belt refresh counter according to the size of the recording material each time the recording material passes through the fixing device F. In this embodiment, as an example, the size is determined by treating a length in the paper transport direction of less than 324 mm as small size and 324 mm or more as large size, and the above count is also 1 for small size and 2 for large size.

The operating conditions for the refresh mode are, first, when the print operation ends after the fixing belt refresh count value exceeds 500. Second, when the size of the recording material is changed from the small size to the large size during the print operation after the refresh counter value exceeds 20, the print operation is temporarily interrupted and the refresh mode operation is executed.

The accumulated counters are cleared after the refresh mode is executed or the fixing belt is replaced.

<Explanation of oil leakage from the inside of the fixing belt>
FIG. 7 is a diagram showing the inner surface of the fixing belt.

When too much oil is applied to the inner surface of the belt, the oil supplied from the oil application roller is scraped off, and the oil blocked at the fixing pad position is released by the attachment/detachment operation of the fixing unit. When the released oil exceeds the saturation threshold of the inner surface of the fixing belt, the oil leaks from inside the belt along the belt position detection flag 394 to the separation metal plate 395.

<Relationship between belt driving speed and oil supply amount under different oil application roller conditions>
FIG. 8 is a diagram showing the relationship between the fixing belt driving speed in each state of the oil application roller and the amount of oil applied to the fixing belt as a lubricant supplied to the belt position detection unit flag 394 during refresh control.

There is no apparent difference in the tendency for the amount of oil supplied that reaches the belt position detection unit flag 394 to increase as the rotation speed of the fixing belt increases. However, the amount of oil supplied differs between the initial state when the cumulative count value of the oil application roller is less than 4000 and the stable state after the cumulative count value of the oil application roller exceeds 4000. It has been confirmed that the saturation threshold at which oil leaks occur is exceeded when the drive speed of the fixing belt exceeds 200 mm/s.

The oil application roller count is reset when the oil application roller is replaced. When a service technician or other person replaces the oil application roller, the device recognizes that the oil application roller has been replaced by having the service technician press a reset button, etc.

<Explanation of Flowchart of the Example>
Next, a control flow during a refreshing operation of the belt 310 in this embodiment will be described with reference to FIGS.

FIG. 9 shows a flow for determining the conditions for implementing refresh control.
After the print operation starts (S101), the cumulative counter of the fixing belt is incremented according to the paper size at the time of printing (S102).
Next, the value of the fixing belt cumulative counter is checked (S103), and if the value of the fixing belt cumulative counter exceeds 20, the presence or absence of the next print data is checked (S104).
If there is next print data, the paper size of the current print data and the paper size of the next print data are confirmed (S105).
If the current print paper size is small and the next print paper size is large, the refresh control execution flag for performing refresh control is turned ON (S107), and the print operation is stopped (S109).
In addition, in determining the paper size, as an example, a length in the paper transport direction of less than 324 mm is treated as a small size, and a length of 324 mm or more is treated as a large size.

If there is no next print data, the printing operation is stopped (S109).
The current print paper size and the next print paper size are confirmed (S105). If the print paper size does not change from small to large, it is then confirmed whether the value of the fixing belt cumulative counter exceeds 500 (S106). If the value of the fixing belt cumulative counter exceeds 500, the refresh control execution flag is turned ON (S107).
Next, the presence or absence of next print data is checked (S108), and if there is next print data, the printing operation continues and the process from S102 onwards is carried out for the next print data. If there is no next print data, the printing operation is stopped (S109).
FIG. 10 shows a flow for determining settings during refresh control operation.

First, in order to determine whether or not a refresh operation needs to be performed when a print job is completed, it is checked whether or not a refresh control execution flag is set (S201).
If the refresh control execution flag is ON, it is then confirmed whether the value of the cumulative counter for the oil application roller is less than 4000 (S202).
The counter value of the oil application roller is incremented every time printing is performed, like other counters.

If the value of the cumulative counter of the oil application roller is less than a predetermined value (less than 4000), the drive speed of the fixing unit is set to 64.5 mm/s (first speed) (S203).
If the value of the cumulative counter of the oil application roller is equal to or greater than a predetermined value (4000 or greater), the drive speed of the fixing unit is set to 248 mm/s (second speed) (S204).
Next, the refresh control is executed at the set fixing unit drive speed (S205).
After the refresh control is executed, the refresh control execution flag is turned OFF (S206), the fixing belt cumulative counter is cleared (S207), and the refresh control operation is terminated.

<Confirmation results when using control flow>
By using the control flow of the embodiment, the amount of oil supplied to the fixing belt position detection unit during refresh control does not exceed the saturation threshold. It was confirmed that the refresh control can be performed at an appropriate speed according to the state of the oil application roller without causing oil leakage from inside the fixing belt.

F fixing device N nip portion 300 heating unit 310 fixing belt (belt)
320 Pressure Pad (Pad)
330 Pressure roller 340 Heat roller 350 Steering roller 360 Stay 370 Lubricating sheet 380 Fixing frame 381 Heating unit positioning section 390 Fixing belt refreshing roller 391 Pressure roller refreshing roller 392 Heat roller thermistor 393 Oil application roller 394 Belt position detection section

Claims (4)

a fixing belt that is endless and applies heat to the recording material;
a fixing pad disposed on an inner circumferential surface of the fixing belt;
a pressure rotating body that is in contact with the fixing belt;
The pressure rotating body forms a nip portion together with the fixing belt, and the toner image is fixed to the recording material by applying heat and pressure to the recording material carrying the toner image at the nip portion.
a rotation control unit for controlling a rotation speed of the fixing belt;
an oil application member that applies oil to an inner circumferential surface of the fixing belt;
a polishing member that contacts an outer peripheral surface of the fixing belt and polishes the outer peripheral surface of the fixing belt;
the polishing member is capable of coming into contact with and being separated from the fixing belt,
A counter for counting the number of sheets of recording material that have been printed;
when the number of sheets of recording material counted by the counter after the oil application member is replaced is less than a predetermined value and the grinding member grinds the fixing belt, the rotation control unit controls the rotation speed of the fixing belt to a first speed,
an image forming apparatus characterized in that, when the number of recording materials counted by the counter after the oil application member is replaced is equal to or greater than the predetermined value and the polishing member polishes the fixing belt, the rotation control unit controls the rotation speed of the fixing belt to a second speed faster than the first speed. a steering roller that contacts an inner circumferential surface of the fixing belt;
a belt position detector having a contact portion that contacts an end of the fixing belt and a detector that detects a position of the contact portion;
a steering control unit that performs control to swing the steering roller so as to change a position of the fixing belt in a width direction of the fixing belt based on a detection result of the belt position detection unit;
2. The image forming apparatus according to claim 1, further comprising: 2. The image forming apparatus according to claim 1, wherein the oil application member is in the form of a rotatable roller. 2. The image forming apparatus according to claim 1, wherein the oil application member comprises felt.

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