JP2007108655A - Image heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent control of the meandering of a belt from becoming unstable in the operation for placing the belt in contact with a fixation roller, and the operation for separating the belt from the fixation roller. <P>SOLUTION: When the main assembly of an image forming apparatus is kept on standby, the fixation roller 1 remains stopped, whereas the belt is continuously rotated at 50 mm/s by a belt motor, which drives the belt for standby, while being kept separated from the fixation roller 1. Then, at the same time as the main assembly begins a printing operation, the fixation roller 1 begins to rotate at 50 mm/s, which is a second rotational speed, and the belt begins to be pressed upon the fixation roller 1. Then, as the pressure gradually builds up and reaches its preset full strength, the rotational speed of the fixation roller is increased to a first fixation speed, or 200 mm/s, before paper is introduced into a fixation nip. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image heating apparatus for heating an image on a recording material. Examples of the image heating device include a fixing device that fixes an image on a recording material, and a device that improves the glossiness of an image by heating the image fixed on the recording material. The image heating apparatus is used in an image forming apparatus such as a copying machine, a printer, or a facsimile.

  2. Description of the Related Art An electrophotographic apparatus such as a copying machine, a printer, or a facsimile machine using toner is provided with a fixing device that melts and fixes a toner image transferred on a recording medium.

  A belt fixing device using a belt as a fixing device is proposed in Patent Document 1. Such a belt fixing device is equipped with a belt meandering control mechanism. In this meandering control mechanism of the belt, the direction of the belt and the moving speed thereof are controlled by intentionally changing the inclination of one of the rollers that suspend the belt. In this belt fixing device, the belt is separated from the fixing roller during non-fixing.

FIG. 11 shows an operation sequence of the belt fixing device described in Patent Document 1. As shown in FIG. 11, according to this sequence, the rotation of the fixing roller is stopped during standby, while the belt is rotating in a state of being separated from the fixing roller. In this state, when a copy start signal is input, the fixing roller starts to rotate at the fixing speed. When the fixing roller is rotating at the fixing speed, the belt starts to contact / press the fixing roller, and the pressing operation is completed after a certain time. Thereafter, the sheet enters the fixing nip.
JP-A-11-231701

  However, when the fixing roller and the belt are operated according to such a conventional sequence, the following problems occur.

  That is, in the prior art, at the start of image formation, when the belt is brought into contact with the fixing roller, the fixing roller rotates at a high speed during fixing. As a result, the meandering control of the belt becomes unstable and the belt position may deviate from the normal meandering range. This phenomenon is remarkable when the fixing speed of the fixing roller is increased as the image forming speed is increased.

  When such a phenomenon occurs, a belt meandering control error occurs and it is necessary to forcibly stop the image forming operation. Until this is restored, image formation becomes impossible. Therefore, it is inconvenient for an operator who wants to quickly perform image formation.

  Accordingly, an object of the present invention is to provide an image heating apparatus capable of satisfactorily swinging a belt in its width direction.

In order to achieve the above object, the present invention provides:
A heating rotator that heats an image on a recording material at a nip portion, a belt that forms the nip portion between the heating rotator, and a swinging means that swings the belt in the width direction of the belt And a control means for controlling the rotation speed of the heating rotator, wherein the belt moves between a position in contact with the heating rotator capable of heating operation and a position retracted from the heating rotator. The control means can rotate the heating rotator at a low speed when the belt is brought into contact with the heating rotator while the belt is oscillated by the oscillating means, and before the heating operation is started. The heating rotator is increased in speed.

  As described above, according to the present invention, the belt can be favorably swung in the width direction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals. First, an outline of the entire image forming apparatus will be described. Thereafter, a fixing device as an image heating device according to the present invention will be described.

(Image forming device)
The image forming apparatus will be described with reference to FIG. As shown in FIG. 10, the image forming apparatus includes first, second, third, and fourth image forming units (image forming means) Pa, Pb, Pc, and Pd, and toner images of different colors. Is formed through a process of latent image, development and transfer.

  The image forming portions Pa, Pb, Pc, and Pd are respectively provided with dedicated image carriers, and in this embodiment, electrophotographic photosensitive drums 303a, 303b, 303c, and 303d, and the photosensitive drums 303a, 303b, and 303c are provided. , 303d, toner images of respective colors are formed. An intermediate transfer member 1130 is installed adjacent to each of the photosensitive drums 303a, 303b, 303c, and 303d. The toner images of the respective colors formed on the photosensitive drums 303a, 303b, 303c, and 303d are primarily transferred onto the intermediate transfer member 330 and transferred onto the recording material p at the secondary transfer portion. Further, the recording material p onto which the toner image has been transferred is fixed to the toner image by heating and pressurizing with the fixing device 100 and then discharged out of the apparatus as a recorded image.

  Drum chargers 302a to 302d, developing devices 301a to 301d, primary transfer chargers 324a to 324d and cleaners 304a to 304d are provided on the outer circumferences of the photosensitive drums 303a to 303d, respectively. A light source device and a polygon mirror (both not shown) are further installed in the upper part of the apparatus.

The laser light emitted from the light source device is scanned by rotating the polygon mirror, the light beam of the scanning light is deflected by the reflecting mirror, and the photosensitive drums 303a, 303b, 3 and 3 are deflected by the fθ lens.
The light is condensed and exposed on the buses 03c and 303d. As a result, latent images corresponding to the image signals are formed on the photosensitive drums 303a, 303b, 303c, and 303d.

  The developing devices 301a, 301b, 301c, and 301d are filled with predetermined amounts of yellow, magenta, cyan, and black toners as developers, respectively, by a supply device (not shown). The developing devices 301a, 301b, 301c, and 301d develop the latent images on the photosensitive drums 303a, 303b, 303c, and 303d, respectively, and visualize them as cyan toner images, magenta toner images, yellow toner images, and black toner images.

  The intermediate transfer member 330 is driven to rotate in the direction of the arrow at the same peripheral speed as the photosensitive drum 303.

The first color yellow toner image formed and supported on the photosensitive drum 303 a passes through the nip portion between the photosensitive drum 303 and the intermediate transfer member 330. In this process, intermediate transfer is performed on the outer peripheral surface of the intermediate transfer body 330 by the electric field and pressure formed by the primary transfer bias applied to the intermediate transfer body 330.

  Similarly, the second color magenta toner image, the third color cyan toner image, and the fourth color black toner image are sequentially superimposed and transferred onto the intermediate transfer body 330, and a composite color toner image corresponding to the target color image is obtained. It is formed.

  Reference numeral 311 denotes a secondary transfer roller, which corresponds to the intermediate transfer member 330 and is arranged in parallel and in contact with the lower surface portion. A desired secondary transfer bias is applied to the secondary transfer roller 311 by a secondary transfer bias source.

  Transfer of the composite color toner image superimposed and transferred onto the intermediate transfer body 330 to the recording material P is performed as follows.

  That is, the recording material P is fed from the sheet feeding cassette 300 to the contact nip between the intermediate transfer member 330 and the secondary transfer roller 311 through a registration roller 312 and a pre-transfer guide at a predetermined timing. At the same time, a secondary transfer bias is applied from a bias power source. The composite color toner image is transferred from the intermediate transfer member 330 to the recording material P by the secondary transfer bias.

  The photosensitive drums 303a, 303b, 303c, and 303d that have undergone the primary transfer are cleaned and removed of the transfer residual toner by the respective cleaners 304a, 304b, 304c, and 304d, and are subsequently prepared for forming the next latent image or less. Toner and other foreign matters remaining on the intermediate transfer body 330 are wiped by contacting a cleaning web (nonwoven fabric) with the surface of the intermediate transfer body 330.

  The transfer material P that has received the transfer of the toner image is sequentially introduced into the fixing device 100, fixed by applying heat and pressure to the transfer material, and then output through the paper discharge unit 363.

(Fixing device)
Next, the fixing device 100 as the image heating device according to the present invention will be described. FIG. 2 shows a cross-sectional configuration of the fixing device 100. Here, the fixing roller 1 as a heating rotator incorporating a heating source and the belt unit 20 are mainly described.

  As shown in FIG. 2, the belt unit 20 includes an endless belt 10 and a pressure applying member 4 that applies pressure from the inner surface toward the fixing roller 1 at a fixing nip portion of the belt 10. Further, the belt unit includes a separation roller 5, a steering roller 6, and an inlet roller that are three support rollers for stretching the belt. The fixing device 100 of this example includes a meandering control mechanism as a swinging unit that swings the belt described above in the width direction. This point will be described later.

  The fixing roller 1 includes a cylindrical cored bar 1a formed of a metal having high thermal conductivity such as aluminum, an elastic layer 1b made of an elastic material such as silicone rubber, and heat resistance such as a PFA tube. It has a roll structure in which a release layer 1c having excellent release properties is laminated in order. A halogen lamp 2 as a heating source is disposed inside the cylinder of the metal core 1a.

A temperature sensor 3 for detecting the surface temperature of the fixing roller 1 is disposed on the surface of the fixing roller 1. Then, the controller 16 as control means controls (feedback control) the lighting of the halogen lamp 2 based on the output signal from the temperature sensor 3 so that the surface of the fixing roller 1 is maintained at a predetermined fixing temperature. It has become. The fixing roller 1
Is configured such that the driving force of the driving motor M is transmitted through the drive transmission gear train X and rotates in the direction of the arrow in the figure (see FIG. 2).

  Further, a plurality of rotation speeds (50 mm / s, 200 mm / s) are prepared for the fixing operation (heating operation) of the fixing roller 1. The rotational speed of the fixing roller 1 is selected from these according to the type of recording material. Specifically, the output of the drive motor M can be switched by the controller 16 (FIGS. 2 and 3) according to the type of recording material. Here, in this example, information corresponding to the type of the recording material is configured to be input by an operator, and the controller performs control based on this information. From the viewpoint of operability, it is preferable that the recording material type is automatically detected by a recording material type discrimination sensor provided in the image forming apparatus, and the controller performs control based on the detected result.

  Specifically, in this example, when the recording material is thin (thin paper or plain paper), the rotation speed of the fixing roller 1 is controlled by the controller 16 so as to rotate at a high speed (200 mm / s). . Therefore, the belt configured to rotate while being in contact with the fixing roller 1 also rotates at this rotational speed.

On the other hand, when the recording material is thick (thick paper or coated paper), the rotation speed of the fixing roller 1 is controlled by the controller 16 so as to rotate at a low speed (50 mm / s) slower than the speed described above. Therefore, the belt configured to rotate while being in contact with the fixing roller 1 also rotates at this rotational speed.

  The belt unit 20 is a state in which a belt 10 formed of a heat-resistant resin film such as a polyimide film is wound around three separation rollers 5, a steering roller 6, and an inlet roller 7 that are rotatably supported. It is installed at.

  The separation roller 22 is a pressure roller that is rotatably arranged so as to press the fixing roller 1 through the belt 10 by a pressure mechanism (not shown). The elastic layer 1 b of the fixing roller 1 is deformed by the separation roller 5, and the toner image that has advanced into the fixing nip due to the deformation distortion is separated from the fixing roller 1.

  Further, in this example, when the fixing operation is completed, the moving unit 1000 has a moving mechanism 1000 that moves the belt unit in the direction of the arrow W about the rotation center Z to a position where the belt is separated from the fixing roller. Figure 2). On the other hand, when an image formation start signal is input, the moving mechanism 1000 moves the belt unit about the rotation center Z in the direction opposite to the arrow W direction so that the belt contacts the fixing roller 1. Let

  In this example, as will be described later, even when the belt is in a retracted position separated from the fixing roller, the belt is rotated at a low speed (50 mm / s) to stand by. This is because the halogen heater built in the inlet roller 7 is turned on even during standby, and the temperature of the entire belt is adjusted to the standby temperature. As a result, when an image formation start signal is input, it is possible to quickly return from a standby state to a state where a fixing operation (heating operation) is possible.

Accordingly, in the standby state in which the belt is separated from the fixing roller 1, the belt is rotated by the driving force input from the driving motor M ′ to the separation roller via the driving transmission mechanism Y (FIG. 2). . As described above, the belt is configured to be rotated by the fixing roller during the fixing operation (heating operation). That is, in this example, during the fixing operation, the controller 16 turns off the drive motor M ′, so that no drive force is input to the separation roller. Note that the separation roller may be driven by the drive motor M ′ as long as the belt does not prevent the belt from following the fixing roller during the fixing operation.

  The steering roller 6 as the swinging means functions to swing the belt in the width direction by adjusting the inclination according to the position in the width direction of the belt. That is, the controller 16 as a swinging unit adjusts the inclination of the steering roller in accordance with the position in the width direction of the belt, so that the position in the width direction of the belt can be fixed within a predetermined swing range in which a fixing operation (heating operation) is possible. Oscillation control is performed so as to fit inside. Details of this will be described later.

  The inlet roller 7 is disposed at the entrance to which the paper is conveyed, and is placed on the pressure applying member 4 so that the paper is introduced flat with respect to the fixing nip formed by the fixing roller 1 and the pressure applying member 4. Arranged in parallel.

  Further, as described above, the inlet roller 7 has a built-in halogen heater so that the belt is heated when the belt is in the retracted position away from the fixing roller. In this example, when the belt is in contact with the fixing roller 1 and is in a position where a fixing operation (heating operation) is possible, the energization of the halogen heater is turned off.

  The pressure applying member 4 is formed by forming an elastic layer 4b such as silicone rubber on a support plate 4a, and further laminating a low friction layer 4c such as a fluorine resin coat, and the like via a belt 10 by a pressure mechanism (not shown). It is pressed against the fixing roller 1.

(Meander control means)
Next, the configuration of the meandering control means as the belt swinging means will be described. FIG. 3 is a diagram showing a belt unit of the belt fixing device and its meandering control means. In order to mainly explain meandering control, a heating source and a pressure member are omitted.

  Reference numeral 10 denotes a belt, and reference numerals 5 and 7 denote two of three rollers that stretch the belt 10 from the inside. Reference numeral 6 denotes a roller that tensions the belt 10 from the inner side and applies tension similarly to the stretching rollers 5 and 7, and a steering roller that controls meandering of the belt 10. The steering roller 6 is formed by integrally molding an elastic layer of silicone rubber on the steering roller shaft 6a.

  The steering roller 6 can be changed in inclination (angle) by steering roller holders 11 and 12 that are movable in opposite phases. The moving direction and the moving speed related to the width direction of the belt 10 are controlled by adjusting the angle θ of the steering roller 6 with respect to the belt 10 by the controller 16.

  The steering roller holder 12 has a sawtooth gear groove formed at the end of the member. The steering roller holder 12 is movably controlled by meshing with a meander control motor gear 13 coupled to a meander control motor 14.

  The meandering control motor 14 is supplied with power by a power supply 15 and is finally controlled by a controller 16 electrically connected to the power supply 15. The controller 16 is electrically connected to a belt position sensor 17 as detection means.

Next, the mechanism of this belt position sensor will be described. In other words, a flag is provided at the other end of the arm member 18 that is pressed against the end of the belt 10 by a spring. This flag is configured to block one of the five photosensors arranged in the belt position sensor 17 so that the position in the width direction of the belt 10 (end portion) can be specified. As a result, the controller 16 controls (feeds back) the meandering of the belt (whether to change the inclination of the steering roller) based on a signal from the belt position sensor 17 indicating the position of the belt 10 (end portion) in the width direction.

  Here, the five photosensors constituting the belt position sensor 17 are arranged so as to detect the following positional relationship. That is, the positional relationship is “emergency stop because it is too close to the front side”, “control is started to move to the back side because it is close to the front side”, and “the belt is in the central area”. Further, it is possible to detect a positional relationship such as “starting control to move to the near side because it is approaching the back side” and “emergency stop because it is too close to the back side”.

Further, the size of the arm member 18 covering the photo sensor of the belt position sensor 17 and the interval between the photo sensors always cover any one of the sensors so that position information is not lost. Note that “front side” and “back side” used in this embodiment correspond to the “Front” side and “Rear” side of the image forming apparatus, as shown in FIGS. 1 and 4 to 8. For example, when the belt approaches the front side of the image forming apparatus, it is referred to as “the belt approaches the front side”.

  Next, the belt meandering control operation will be described with reference to FIGS. The solid arrows drawn in the wave shape in FIGS. 4 to 7 represent the position of the belt, the amount of movement thereof, and the movement of the belt in the rotational direction, detected by the arm member in contact with the position of the end of the belt. Yes. “Clip off” and “angle switching” correspond to the photosensors of the belt position sensor, respectively, and the position of the belt reaches these positions.

  “Angle switching” means that the control angle of the steering roller changes to an opposite phase. In the case of “offset”, it means to stop the rotation of the fixing device as a close error in order to prevent the belt from being broken.

  Further, the meandering control is performed by rotating the angle θ of the steering roller to the + side when moving the belt toward the front side of the longitudinal direction, and rotating the angle toward the negative side when moving the belt toward the back side. FIG. 4 is a diagram showing an ideal control operation when it is assumed that there is no control delay. The belt rotation speed is 50 mm / s, the belt load is 0 N assuming a standby state, and meandering is performed. The control angle is controlled at +4 and -4 degrees.

  In a very ideal state as shown in FIG. 4, the longitudinal reciprocation of the belt is always reversed when the belt position sensor detects the end of the belt at the “angle switching” position. And start moving. Therefore, the end of the belt does not reach the offset position unless the amount of deviation of the belt due to misalignment of the unit itself exceeds the amount of movement of the belt that can be controlled by the control angle of the steering roller.

  However, in reality, there is a so-called control delay in meander control. This control delay is, for example, a gear backlash. All the gears have a slight margin for meshing to suppress problems such as gear locking and gear cracking. Therefore, when a gear that has been rotating in one direction is rotated in the reverse direction, there is a slight time delay until the gears are engaged again in the reverse direction.

  In addition to the gear backlash, it takes some time to change the steering roller angle. Furthermore, although it is extremely small, the time from the detection by the belt position sensor until the controller performs internal calculation and the control operation is started also causes the control delay.

  FIG. 5 shows actual belt meandering control having such a control delay. As shown in FIG. 4, the belt rotation speed is assumed to be 50 mm / s and the belt load is assumed to be 0 N. However, because of the control delay, the “angle switching” detection position is The control margin up to the detection position is about 24%. 24% of this control margin is in a sufficiently stable state in terms of control.

  Next, a description will be given of the state of the meandering control of the belt when the belt load is kept at 0 N and the belt rotational speed is increased to 200 mm / s. Since the rotation speed of the belt is four times that in the state shown in FIG. 5, the control margin bite due to the control delay is increased to about 96%. For this reason, in this state, the meandering control is in a state where there is not enough room, and it is not a strange state when an error occurs.

  Further, in FIG. 7, meandering is assumed when the belt rotational speed is increased to 200 [mm / s] and the belt is pressed against the fixing member at the same time and its load is 490 [N]. The state of control is shown. The rotation speed of the belt is the same as the conditions described in FIG. However, since the load force is applied to the belt, the moving speed in the longitudinal direction of the belt is lowered, and the bite of the control margin due to the control delay is also reduced to about 12%.

  The deviation of the belt is caused by misalignment of the unit itself. However, as long as the amount of displacement of the belt does not exceed the amount of movement of the belt that can be controlled by the control angle of the steering roller, the belt fixing device results in that the belt rotation speed is slower or the load applied to the belt is higher. The meandering control is stable.

  As described above, the stability of the meandering control of the belt fixing device depends on the amount of misalignment of the belt fixing device, the amount of control delay, the steering roller angle, the rotational speed of the belt, the load force, and the like. I understand.

  The right side of FIG. 8 is a diagram showing the rotation / stop of the heat fixing member and belt and the attaching / detaching operation by the moving mechanism 1000 in the prior art. The left side of FIG. 8 shows a corresponding state at the moment when the meandering control of the belt fixing device becomes unstable. First, when the operation of the main body is in the standby state, the fixing roller as the heat fixing member is stopped, the belt is separated from the fixing roller, and the belt is driven at the time of 50 [mm / s] by driving the belt during standby. It is rotating. In this state, since there is a margin in the control margin of the belt meandering control, the meandering control can be performed stably.

  Next, at the same time as the main body starts the printing operation, the fixing roller starts to rotate at 200 [mm / s], and at the same time, the belt starts to press the fixing roller. Here, first, the belt is driven at a speed of 200 [mm / s] from the moment when it starts to contact the fixing roller, but there is a moment when the pressure is not sufficiently applied. However, in this state, if the meandering control of the belt happens to perform an angle switching operation or is in a state before and after that, the meandering control margin of the belt is almost eliminated, so that a deviation error occurs very easily.

  Therefore, in this example, the meandering control of the belt as described below is stabilized. This will be described with reference to FIGS.

The right side of FIG. 1 is a diagram showing rotation / stop and attachment / detachment operations of the fixing roller and belt according to the embodiment of the present invention. On the other hand, the left side of FIG. 1 is a diagram showing a state in which the corresponding meandering control of the belt is stably executed. FIG. 9 simply shows the rotation and attachment / detachment operations of the fixing roller 1 and the belt 10 at this time.

  First, when the operation of the image forming apparatus main body is in a standby state, the fixing roller is stopped. On the other hand, the belt 10 is rotated at 50 [mm / s] by the drive motor while being separated from the fixing roller 1. In this state, since there is a margin in the control margin of the meandering control of the belt 10, the meandering control is executed stably.

  Next, a case where image formation is started on a thin recording material such as thin paper or plain paper will be described. First, when a print start signal is input to the image forming apparatus, the fixing roller has a lower rotational speed of 50 [mm] among a plurality of fixing speeds (50 [mm / s] and 200 [mm / s]). / S] to start rotation. At substantially the same time, the belt 10 moves from the retracted position to the operating position, and the belt starts to press the fixing roller 1.

  Thus, in this example, when the belt comes into contact with the fixing roller, the fixing roller and the belt 10 are rotated at a slow rotational speed that is the standby speed, that is, 50 [mm / s]. It is possible to stabilize meander control.

  For this reason, even if the timing at which the belt contacts the fixing roller overlaps with the timing at which the belt 10 is shifted (or the timing before and after that), the belt meandering control margin does not decrease. Therefore, there is no fear that the belt exceeds the normal meandering range (swinging range) and the image forming apparatus must be stopped (the print job must be interrupted).

  As the pressure increases gradually, the meandering control of the belt 10 becomes more stable, and the rotation speed of the fixing roller 1 is increased before the paper is introduced into the fixing nip and in a state where the pressure is sufficiently increased. The fixing speed is increased to 200 [mm / s]. Therefore, the stability of the meandering control of the belt can be maintained even if such speed increase is performed.

  When image formation is started on a thick recording material such as thick paper or coated paper, the belt 10 and the fixing roller do not increase in speed even after the belt abuts the fixing roller and the pressure is sufficiently increased. The rotation is continued at the fixing speed of 50 [mm / s].

  Depending on the type of recording material, the rotation speed of the fixing roller (belt) during fixing may be further increased. In this case, the rotation speed after the speed increase of the fixing roller is appropriately determined by the controller according to the type of recording material. Change it. Further, when the rotation speed of the fixing roller (belt) at the time of fixing is 3 or more, the rotation speed of the fixing roller when the belt is brought into contact with the fixing roller is set to the slowest speed among the 3 speeds. Is preferred.

  As described above, in the belt fixing device having the meandering control function, it is possible to prevent the meandering control of the belt from becoming unstable when the belt is brought into contact. That is, a high-quality image can be obtained while increasing the speed.

  As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, The various deformation | transformation based on the technical idea of this invention is possible. For example, the numerical values given in the above embodiment are merely examples, and different numerical values may be used as necessary.

Specifically, for example, in the above-described embodiment, the rotation speed of the fixing roller at the time when the belt is brought into contact with the fixing roller is the slower rotation speed among a plurality of rotation speeds during the fixing operation (heating operation). Although it is set as the structure to select, it is not restricted only to such a structure. For example, a rotation speed that is slower than the fastest rotation speed among a plurality of rotation speeds capable of fixing operation of the fixing roller may be selected without selecting from a plurality of rotation speeds capable of fixing operation of the fixing roller.

In the above-described example, the rotation speed of the belt 10 during standby is set to a fixing speed (50 [mm / s]) for thin paper or plain paper, but is not limited to such a configuration. For example,
The rotation speed of the belt 10 during standby may be 30 [mm / s] which is not the fixing speed.

  In the above-described embodiment, the configuration in which the belt is suspended by the three rollers has been described. However, the configuration is not limited to the configuration in which the number of the suspension rollers is three, and the separation roller and the steering roller are the two rollers. The configuration may be such that the belt is suspended.

  In the above-described embodiment, a “roller” is used as a member on the fixing side (the side in contact with the image on the recording material), and the pressure side (the side opposite to the surface on which the image of the recording material is formed). Although the example using the "belt" of a member was demonstrated, this invention is not restricted only to such an example. For example, the above-described “belt” may be used as the fixing-side member, and the above-described “roller” may be used as the pressing-side member.

  Further, although the fixing device has been described as an example of the image heating device, the present invention can be applied to the following devices. For example, the present invention can also be applied to an apparatus (use) for hypothetically attaching a toner image to a recording material and an apparatus (use) for reheating a toner image that has been presupposed to improve the glossiness of the image.

FIG. 7 is a diagram illustrating meandering control and attachment / detachment operation of the fixing device according to the present invention. 3 is a cross-sectional view illustrating a portion of the fixing device according to the present invention excluding a meandering control device. FIG. FIG. 3 is a cross-sectional view illustrating a meandering control device of the fixing device of the present invention. It is a figure which shows the theoretical operation | movement without a control delay in meandering control. It is a figure which shows the operation | movement of meandering control which considered the control delay considering the belt separated state. It is a figure which shows the operation | movement of meander control when a belt rotates at high speed in the state without a pressurizing force. It is a figure which shows the operation | movement of meander control when a belt rotates in a pressurized state and at high speed. It is a figure which shows the operation | movement of meandering control when the belt | belt in a prior art performed wearing operation | movement, rotating at high speed. FIG. 6 is a cross-sectional view illustrating the attaching / detaching operation of the fixing device according to the present invention. 1 is a cross-sectional view illustrating an overall configuration of an image forming apparatus according to the present invention. It is a figure showing the drive and attachment / detachment operation | movement of a fixing roller and a belt in a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing roller 1a Metal core 1b Elastic layer 1c Release layer 2 Halogen lamp 3 Temperature sensor 4 Pressure applying member 4a Support plate 4b Elastic layer 4c Low friction layer 5 Separating roller 6 Steering roller 6a Steering roller shaft 7 Inlet roller 10 Belt 11, DESCRIPTION OF SYMBOLS 12 Steering roller holder 13 Meander control motor gear 14 Meander control motor 15 Power supply 16 Controller 17 Belt position sensor 18 Arm member 20 Belt unit 22 Separation roller 100 Fixing device 300 Paper feed cassette 301a-d Developer 302a-d Drum charger 303, 303a To d photosensitive drums 304a to d cleaner 311 primary transfer roller 312 registration roller 324a to d primary transfer charger 330 intermediate transfer member 363 paper discharge unit 1000 moving mechanism 1130 intermediate transfer body

Claims (5)

A heating rotator for heating the image on the recording material at the nip,
A belt that forms the nip portion with the heating rotator, the belt being movable between a position in contact with the heating rotator capable of heating operation and a position retracted from the heating rotator; ,
Rocking means for rocking the belt in its width direction;
In an image heating apparatus having a control means for controlling the rotation speed of the heating rotator,
The control means rotates the heating rotator at a low speed when the belt is brought into contact with the heating rotator while operating the swinging means, and accelerates the heating rotator before starting the heating operation. An image heating apparatus.   2. The image heating apparatus according to claim 1, wherein the control unit changes the rotational speed of the heating rotator after the speed increase according to the type of the recording material.   When the belt is brought into contact with the heating rotator while operating the swinging means, the control means rotates the heating rotator at the slowest peripheral speed among the peripheral speeds during the heating operation. The image heating apparatus according to claim 1.   The control means selects either a mode for increasing the peripheral speed of the heating rotator or a mode for maintaining the peripheral speed of the heating rotator at a low speed according to the type of recording material. Item 4. The image heating apparatus according to Item 3.   The image heating apparatus according to claim 1, wherein the heating rotator includes a roller.

Images