JP7106336B2 - Fixing device - Google Patents

Description

The present invention relates to a fixing device used in an image forming apparatus capable of forming an image on a recording material, such as a copying machine, a printer, or a facsimile machine employing an electrophotographic method.

When the heat treatment of the recording material accumulates in the fixing device, the surface condition of the contact area of the recording material in the longitudinal direction (generatrix direction) of the rotating body, which is the fixing member, is higher than that of the non-contact area outside the contact area of the recording material. is getting rough. When the recording paper is cut during the manufacturing process, burrs (paper edges) are generated at the edges of the recording paper. Make a slight scratch (edge scratch) on the surface of the fixing member. That is, when the fixing process of recording materials of the same size (for example, small size) is repeated, edge scratches are repeatedly formed at the same position in the longitudinal direction of the fixing member, so that the surface condition of the area through which the edge passes is particularly likely to become rough. .

On the other hand, Patent Document 1 discloses a fixing device that intermittently rubs a cleaning web made of nonwoven fabric as a rubbing member against a rotating body so that the surface condition of each region in the longitudinal direction of the rotating body is brought closer to uniformity. . Further, in Patent Documents 2 and 3, there is disclosed a refreshing roller (roughening roller) as a rubbing member, in which abrasive grains are fixed on the peripheral surface, and the peripheral surface of the rotating body is roughened by being rotationally driven with a peripheral speed difference from that of the rotating body. A fixing device equipped with a roller) is shown. Then, every time a predetermined number of sheets of the recording material are heat-treated, the heat treatment of the recording material is stopped, and a rubbing mode is executed in which the roughening roller is rubbed against the rotating body, which is the fixing member.

JP-A-4-213482 JP 2007-199596 A JP 2005-266785 A

Here, when performing the rubbing process using the rubbing member, the rotating body, which is the fixing member, is rotated while being heated. However, if the heating temperature of the rotating body is high, the opposing body (for example, a pressure roller) facing the rotating body is also heated. It takes time and reduces productivity.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device that suppresses the temperature rise of the opposed rotating body due to the execution of the rubbing action.

In order to achieve the above object, a fixing device according to the present invention includes a heating rotator that heats the toner image while being in contact with the unfixed toner image on the recording material at the fixing nip portion; a counter-rotating member that forms the fixing nip portion by means of a counter-rotating member ; a drive source that rotationally drives the counter-rotating member; a rubbing member that rubs against the outer peripheral surface of the heating rotor; a moving mechanism for moving the rubbing member so as to obtain a contact position where the rubbing member contacts the body and a separated position where the rubbing member and the heating rotor are separated from each other; a temperature of the heating rotor; and wherein the heating rotator is configured to be driven to rotate by the counter rotator, wherein the controller controls the target of the heating rotator during a fixing operation. The temperature can be set to a plurality of target temperatures including the lowest first target temperature, and during the fixing operation of heating the unfixed toner image on the recording material at the fixing nip portion, the heating rotation is performed. The temperature of the heating rotor is controlled so that the temperature of the body becomes one of the plurality of target temperatures, the rubbing member is positioned at the contact position, and the heating rotor is driven to rotate by the opposing rotor. A second target in which the temperature of the heating rotating body is equal to or lower than the first target temperature, which is the lowest among the plurality of target temperatures, during the execution of the rubbing action by the rubbing member. It is characterized in that the temperature of the heating rotor is controlled so as to be the temperature.

According to the present invention, since the temperature of the heating rotor is controlled so as to be the second target temperature when the rubbing action is performed, it is possible to suppress the temperature rise of the opposing rotor due to the execution of the rubbing action. can be done.

FIG. 3 is an explanatory diagram of the configuration of the fixing device according to the embodiment of the invention (at the time of pressurization of the refresh roller); FIG. 3 is an explanatory diagram of the configuration of the fixing device according to the embodiment of the invention (when the refreshing roller is separated); FIG. 4 is an explanatory diagram of edge damage caused by attack of paper; It is a schematic diagram of the cross-sectional structure of a refresh roller. 3 is a block diagram of a configuration that mainly controls a fixing device; FIG. 4 is a flowchart including heater temperature control during image formation in the fixing device according to the embodiment of the present invention; 5 is a flowchart for explaining control of the pressure roller in the fixing device according to the embodiment of the present invention when the temperature is high. FIG. 10 is an explanatory diagram showing adverse effects when the temperature of the pressure roller is increased; It is a flow chart explaining rubbing operation of an embodiment of the present invention. FIG. 5 is a diagram showing the relationship between the temperature and hardness of a PFA tube on the surface of a fixing film; FIG. 7 is a diagram showing temperature transition during low temperature control during refreshing in the fixing device according to the embodiment of the present invention; 1 is an explanatory diagram of a configuration of an image forming apparatus equipped with a fixing device according to an embodiment of the present invention; FIG. 1 is a block diagram of a configuration for controlling an image forming apparatus equipped with a fixing device according to an embodiment of the present invention; FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Image forming device)
FIG. 12 is an explanatory diagram of the configuration of the image forming apparatus. FIG. 13 is a block diagram of a configuration for controlling the image forming apparatus. As shown in FIG. 12, the image forming apparatus 100 is a tandem type intermediate transfer type full-color printer in which yellow, magenta, cyan, and black image forming units Pa, Pb, Pc, and Pd are arranged along the intermediate transfer belt 16 . be. As shown in FIG. 13, the image forming apparatus 100 is connected to a PC 1000 using a keyboard 1010 and a mouse 1011 as input devices.

In FIG. 12 , in the image forming station Pa, a yellow toner image is formed on the photosensitive drum 3 a and transferred to the intermediate transfer belt 16 . In the image forming portion Pb, a magenta toner image is formed on the photosensitive drum 3b and transferred to the intermediate transfer belt 16. FIG. In the image forming units Pc and Pd, a cyan toner image and a black toner image are formed on the photosensitive drums 3c and 3d, respectively, and transferred to the intermediate transfer belt 16. FIG.

The four-color toner image transferred to the intermediate transfer belt 16 is conveyed to a secondary transfer portion (described later) and secondarily transferred onto a sheet P as a recording material. Sheets P pulled out from a sheet cassette 10 are fed one by one to registration rollers 12.例文帳に追加The registration rollers 12 send the sheet P to the secondary transfer portion in timing with the toner image on the intermediate transfer belt 16 . The sheet P onto which the four-color toner images have been secondarily transferred is heat-treated by a fixing device 9 as a fixing device to fix the toner images on the surface.

(Image forming section)
The image forming units Pa, Pb, Pc, and Pd have almost the same configuration except that the toner colors used in the respective developing devices 1a, 1b, 1c, and 1d are yellow, magenta, cyan, and black. In the following, the image forming portion Pa will be described, and redundant description of the other image forming portions Pb, Pc, and Pd will be omitted.

The image forming section Pa includes a charging device 2a, an exposure device La, a developing device 1a, a transfer roller 24a, and a drum cleaning device 4a surrounding the photosensitive drum 3a. The photosensitive drum 3a has a photosensitive layer formed on the outer peripheral surface of an aluminum cylinder, and rotates in the direction of the arrow at a predetermined process speed.

The charging device 2a charges the photosensitive drum 3a to a uniform negative potential. The exposure device La writes an electrostatic image on the photosensitive drum 3a by scanning a laser beam obtained by ON-OFF-modulating a scanning line image signal representing an image of each color with a rotating mirror. The developing device 1a transfers toner to the photosensitive drum 3a to develop the electrostatic image into a toner image. An amount of new toner corresponding to the amount of toner consumed in the developing device 1a for image formation is supplied from the toner cartridge Ea to the developing device 1a.

The transfer roller 24 a presses the intermediate transfer belt 16 to form a transfer portion between the photosensitive drum 3 a and the intermediate transfer belt 16 . A negative toner image carried on the photosensitive drum 3a is transferred to the intermediate transfer belt 16 by applying a positive DC voltage to the transfer roller 24a.

The intermediate transfer belt 16 is stretched over and supported by the tension roller 15, the inner secondary transfer roller 14, and the drive roller 13, and is driven by the drive roller 13 to rotate in the arrow A direction. The secondary transfer outer roller 11 contacts the intermediate transfer belt 16 supported by the secondary transfer inner roller 14 to form a secondary transfer portion. The toner image on the intermediate transfer belt 16 is transferred to the sheet P by applying a positive DC voltage to the secondary transfer outer roller 11 .

The drum cleaning device 4a scrapes the photosensitive drum 3a with a cleaning blade to collect the transfer residual toner on the photosensitive drum 3a. The belt cleaning device 22 rubs a cleaning web against the intermediate transfer belt 16 to collect the transfer residual toner on the intermediate transfer belt 16 .

(fixing device)
A fixing device 9 as a fixing device according to an embodiment of the present invention will be described below. The fixing device 9 in this embodiment includes a refresh roller (roughening roller) 120 as a rubbing member (rubbing rotating body), and the refresh roller 120 will be described in detail later. FIG. 1 is a schematic cross-sectional view of the fixing device 9 in the transverse direction (refreshing roller 120 is pressed), and FIG. 2 is a schematic cross-sectional view of the fixing device 9 in the transverse direction (refreshing roller 120 is separated). FIG. 5 is a block diagram mainly for controlling the fixing device 9. As shown in FIG.

In FIGS. 1 and 2, reference numeral 106 denotes a fixing belt (endless belt) as a heating rotating body, which is formed of a cylindrical fixing film. Reference numeral 101 denotes a pressure roller as a counter-rotating member that forms a fixing nip portion (nip portion) that nips and conveys a sheet P as a recording material in cooperation with the fixing belt. A support stay 104 shown in FIG. 1 is arranged inside the fixing belt 106 and supports the nip portion forming member 103 that pressurizes and urges the fixing belt 106 toward the pressure roller 101 .

A pressure spring 113 is compressed between the pressure arm 112 and pressure is applied at the left and right ends in the longitudinal direction (perpendicular to the paper surface of FIG. 1) as follows. That is, the fixing belt 106 is pressed against the upper surface of the pressure roller 101 with a predetermined pressing force via the fixing flange 105 , the support stay 104 and the nip portion forming member 103 . Thereby, a fixing nip portion N having a predetermined width is formed. The applied pressure in this embodiment is 156.8 N at one end in the longitudinal direction, and the total applied pressure is 313.6 N (32 kgf).

Further, in the fixing device 9, the pressure applied to the nip portion can be reduced to a light pressure state. The pressure cam 130 is rotated by a motor (not shown) to push up the pressure arm 112 . As a result, the surface of the pressure cam 130 receives the spring force from the pressure spring 113 , so that the spring force applied from the pressure spring 113 to the fixing flange 105 is reduced. In the present embodiment, changing from a pressurized state to a lightly pressurized state is referred to as a pressurization release operation. In the present embodiment, a configuration in which the nip portion is lightly pressed by the pressure releasing operation will be described as an example, but the pressure releasing operation may separate the fixing belt 106 and the pressure roller 101 from each other.

The width of the nip portion of this fixing device (recording material conveying direction in the plane of FIG. 1) is in the range of 8 mm to 10 mm. The diameters of the fixing belt 106 and pressure roller 101 are φ32 mm and φ31 mm, respectively.

The support stay 104 is desirably made of a material that does not easily bend even when a high pressure is applied, and SUS304 is used in this embodiment.

The nip forming member 103 is a heat insulating member such as a heat-resistant resin elongated in the longitudinal direction perpendicular to the drawing. From the viewpoint of energy saving, it is desirable to use a material with low thermal conductivity to the support stay 104. For example, heat-resistant glass, polycarbonate, and heat-resistant resin such as liquid crystal polymer are used. In this embodiment, Sumika Super E5204L manufactured by Sumitomo Chemical Co., Ltd. was used.

The pressure roller 101 is arranged such that both ends of a core metal are rotatably supported by bearings between side plates on the back side and the front side of the apparatus frame. In this embodiment, a ceramic heater (heater) 102 is used as a heating heater that is a heating member that heats the nip portion via the fixing belt 106 . The heater 102 forms a heating element by printing a thick film of Ag.Pd paste on an Al2O3 substrate and baking the paste.

As means for detecting the temperature of the heater 102, a thermistor (42a in FIG. 5) (not shown) is provided on the side opposite to the surface where the heater 102 slides on the fixing belt 106. FIG. This thermistor detects the temperature of the fixing belt and controls the heater 102 .

The fixing belt 106 has an elastic layer of silicone rubber with a thickness of 300 μm and a rubber hardness of 20° (JIS-A 1 kg weight) disposed around a base layer made of a SUS tube with an inner diameter of 30 mm and a thickness of 200 μm. The surface of the elastic layer is covered with a release layer made of a PFA resin tube having a thickness of 30 μm.

The pressure roller 101 has an elastic layer of silicon rubber with a thickness of 1.0 mm and a rubber hardness of 20° (JIS-A 1 kg weight) disposed around an aluminum base layer with an outer diameter of 30 mm. The surface of the elastic layer is covered with a release layer made of a PFA resin tube having a thickness of 30 μm.

The release layer of the fixing belt 106 may be made of PFA resin (copolymer of tetrafluoroethylene resin and perfluoroalkoxyethylene resin), PTFE (tetrafluoroethylene resin), other fluororesins, and the like. The thickness of the release layer is preferably 10 μm or more and 60 μm or less.

Both ends in the longitudinal direction (rotational axis direction) of the base layer of the fixing belt 106 are rotatably supported by bearing members (not shown). Both ends in the longitudinal direction (rotation axis direction) of the base layer 41b of the pressure roller 101 are rotatably supported by bearing members (not shown). The pressure roller 101 is rotationally driven by a driving motor 92a (FIG. 5). The fixing belt rotates by being driven by the pressure roller.

The peripheral speed of the fixing belt 106 and pressure roller 101 is 100 mm/sec or 300 mm/sec, which corresponds to the process speed (image forming speed) of the image forming apparatus.

The pressure roller 101 comes into contact with the fixing belt 106 when the bearing members supporting both ends in the longitudinal direction are urged toward the fixing belt by a pressure spring (not shown). The pressure roller presses the fixing belt 106 with a total pressure of 200N. The elastic layer is crushed by the pressure, and a nip portion having a predetermined width in the sheet conveying direction is formed between the fixing belt 106 and the pressure roller 101 .

The pressure roller 101 does not need to press the fixing belt 106 while the sheet P is not nipped by the nip portion. While the sheet P is not nipped, the CPU 81 (FIG. 5) as a main body control unit separates the pressure roller 101 from the fixing belt 106 by the contact/separation mechanism. This contact/separation mechanism uses a cam mechanism to lower the pressure roller 101 against a pressure spring (not shown), thereby forcibly separating the pressure roller 101 from the fixing belt 106 .

(Temperature control of fixing belt during image formation)
The temperature control of the fixing belt during image formation will be described in detail in the flow charts (FIGS. 6 and 7) of the printing operation (image forming operation) during image formation. Temperature control is performed at a temperature of 150°C.

A heater 102 (FIG. 1) is arranged inside the fixing belt 106 as a configuration for controlling the temperature of the fixing belt. Also, a temperature sensor is arranged in contact with the surface of the fixing belt 106 . The temperature control circuit raises the temperature detected by the temperature sensor to a target temperature of 150° C., which is the temperature at which the toner can be fixed on the sheet P, and then controls the ON/OFF of the heater 102 so as to maintain the target temperature. The target temperature differs depending on the type of sheet P and the like. Table 1 shows an example of the set fixing speed and the target temperature control temperature of the fixing belt 106 depending on the conditions of the sheet P.

(Influence of Edge Scratches on Fixing Belt)
FIG. 3 is an explanatory diagram of a state in which the fixing device 9 nips and conveys the sheet P at the nip portion, and describes the edge damage. In recent years, there has been a demand for a glossy product that matches the surface properties of the paper (sheet P). When high-gloss coated paper is used, the surface condition of the fixing belt 106 is likely to be reflected in the surface condition of the toner layer. Such a property is called image clarity of the fixed image. As the meltability of the toner improves and the image clarity increases, it becomes important to maintain the surface condition of the fixing belt 106 in order to form a high-quality image with high glossiness.

As shown in FIG. 5, the fixing belt 106 in the initial state had a uniform mirror surface as a whole, and the surface roughness Rz of the circumferential surface was about 0.1 μm to 0.3 μm. Hereinafter, the surface roughness Rz is a JIS ten-point average roughness measured using a surface roughness measuring instrument SE-3400 manufactured by Kosaka Laboratory Co., Ltd. The measurement conditions are feed speed: 0.5 mm/sec, cutoff: 0.8 mm, and measurement length: 2.5 mm.

In the fixing device 9, as the sheet fixing process accumulates, the surface condition of the fixing belt 106 changes due to contact with the edge of the sheet P and contamination such as paper dust and offset toner. It gets rough. The surface of the fixing belt 106 at (I) a passing portion, (II) a non-passing portion, and (III) a boundary area of the fixing belt 106 as the sheet P repeatedly passes through a certain position in the rotation axis direction of the fixing belt 106 . are different.

(I) In the passing portion, the sheet passes and the paper surface comes into contact with it. (I) At the passing portion, the surface of the fixing belt 106 is gradually smoothed by the contact of the fibers of the paper, the filler of the paper, the external additive of the developer, and the like. As the fixing process was accumulated, the surface roughness Rz of the (I) passing portion gradually increased to about 0.5 μm to 1.0 μm.

(II) In the non-passing portion, the sheet does not pass through and does not come into contact with the paper surface. (II) In the non-passing portion, the surface 40 d of the fixing belt 106 exclusively contacts the surface 41 d of the pressure roller 101 . As the fixing process is accumulated, the surface roughness Rz of the (II) non-passing portion is saturated at about 0.4 μm to 0.7 μm.

(III) The boundary area is located at the boundary between the sheet passing area and the non-sheet passing area and repeatedly contacts the edge (edge portion) of the sheet, so the surface roughness Rz is larger than that of the (I) passing portion. The surface roughness Rz of the rough peripheral surface (concavities with no directionality) immediately before the rubbing mode was about 0.5 μm to 2.0 μm.

In the process of fixing the unfixed toner image on the sheet P, minute surface shapes of the fixing belt 106 are transferred to the surface of the fixed image. If the surface state of the fixing belt 106 (I) passing portion and (III) boundary area is different, the surface state of the fixed image is correspondingly different, resulting in gloss unevenness in the fixed image.

Differences in gloss between (III) the boundary region and (I) the passing portion and (III) between the boundary region and the non-passing portion (II) are called edge scratches. Also, the gloss difference (gloss difference) between (I) the passing portion and (II) the non-passing portion is called a gloss level difference. (III) Since the width of the boundary region is narrow at about 1 to 2 mm, regardless of how rough the boundary region (III) is, the gross step between (I) the passing portion and (II) the non-passing portion is wide. It gives a great impression as gloss unevenness (gloss unevenness) in the area.

If the reproducibility of the specularly reflected light image on the image surface is high, the image is evaluated as having high gloss. When a silver salt photograph is viewed under fluorescent lighting, the surface of the photographic image is a mirror surface with few irregularities, so not only the light of the fluorescent lamp is reflected, but also the shape of the fluorescent lamp is reflected. This state is judged to be high gloss. On the other hand, a state in which the reproducibility of the specularly reflected light image on the image surface is low or absent is evaluated as low gloss. In the case of low gloss, the surface of the image has large unevenness, and the light from the fluorescent lamp is diffusely reflected, so that the shape is not reflected on the image. Thus, there is a correlation between the unevenness of the image surface and the glossiness of the output image.

Also, the gloss unevenness of the fixed image depends on the type of the sheet P. As shown in FIG. Even if gloss unevenness is at a level that cannot be visually recognized on plain paper, gloss unevenness becomes conspicuous in fixed images on high-gloss gloss coated paper, which requires high surface smoothness and high image quality. In the fixed image on the gloss-coated paper, low gloss streaks at positions corresponding to the roughened (III) boundary areas of the fixing belt 106 and edge scratches are conspicuous. Since the difference in gloss between them is also conspicuous, gloss unevenness becomes conspicuous in the fixed image.

In this way, the roughness of the surface of the fixing belt 106 differs between (I) the passing portion and (II) the non-passing portion, so that a difference in glossiness occurs on the fixed image. In particular, (III) the boundary area is likely to be roughened, resulting in a difference in gloss between both the (I) passing portion and the (II) non-passing portion.

(refresh roller)
FIG. 4 is a schematic diagram of a cross-sectional structure of the refreshing roller 120 as a rubbing member (rubbing rotating body) in this embodiment. The refreshing roller 120 contacts the outer peripheral surface of the fixing belt 106 in the rubbing mode in which the rubbing process is performed, and restores the surface condition of the fixing belt 106 by rubbing.

The refreshing roller 120 has a rubbing layer 55 in which abrasive grains are tightly adhered via an adhesive layer 54 to the peripheral surface of a base material 53 of a stainless steel pipe (SUS304) having an outer diameter of 12 mm. The rubbing layer 55 can be formed by bonding various commercially available abrasive grains or a mixture of various abrasive grains with the adhesive layer 54 .

Examples of commercially available abrasive grains 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, etc. be.

Here, as the abrasive grains of the rubbing layer 55, aluminum oxide abrasive grains (alumina-based abrasive grains, Alundum, Morundum) were used. Aluminum oxide abrasive grains are the most widely used abrasive grains, and have sufficiently high hardness compared to the fixing belt 106 . In order for the surface roughness of the refreshed fixing belt 106 to satisfy the criteria described later while ensuring the refreshing effect of the surface of the fixing belt 106, the grain size of the abrasive grains of the rubbing layer 55 should be 5 μm or more and 20 μm or less. Experiments have confirmed that this is preferable.

Refresh roller 120 improves the surface condition of fixing belt 106 . That is, the refreshing roller 120 gives a large number of fine rubbing scratches to both the surface (peripheral surface) of the fixing belt 106 that has been roughened by passage of the sheet P and the surface (peripheral surface) that has not been roughened due to passage of the sheet P. to the desired level. Thereby, the difference in the surface state of the surface (outer peripheral surface) in the longitudinal direction of the fixing belt 106 can be reduced.

Here, the purpose of rubbing by the refreshing roller 120 is to make fine rubbing scratches on the surface of the fixing belt 106, not to scrape off the surface of the fixing belt 106 to expose a new surface. That is, the refreshing roller 120 does not substantially scrape off the surface of the fixing belt 106, but scratches the surface.

(contact and separation mechanism)
Roughening roller 120 is provided at a position close to fixing belt 100 so as to be able to contact or separate from the surface (peripheral surface) of fixing belt 100 . 1 shows the contact state (contact position), and FIG. 2 shows the separated state (separated position). Since the refreshing roller 120 does not need to rub against the fixing belt 100 during image formation, the motor control unit 91 operates an actuator as a contact/separation mechanism to separate the refreshing roller 120 from the fixing belt 100 .

When the distance between the rubbing portion of the roughening roller 120 and the outer peripheral surface of the fixing belt 100 when the roughening roller 120 is positioned at the separated position is defined as the first distance, the moving mechanism moves the roughening roller 120 toward its abutment position a second distance that is greater than the first distance.

(Backup material)
A backup member 121 used when executing the rubbing process is arranged inwardly of the fixing belt 106 . When the refresh roller 120 is separated from the fixing belt 106 , the backup member 121 is separated from the inner surface (inner peripheral surface) of the fixing belt 106 and is not pressed.

On the other hand, when the refreshing roller 120 is pressed against the fixing belt 106 , the fixing belt 106 is deformed to form a contact surface necessary for rubbing action between the backup member 121 and the refreshing roller 120 . . Note that the rubbing operation is performed, for example, during an interrupt operation after the end of a print job, or during a manual operation in user mode.

In the rubbing mode, the refreshing roller 120 has countless rubbing scratches (direction thin recesses) are formed along the rotation direction of the fixing belt 106 . The refreshing roller 120 forms scratches (recesses) with a width of 10 μm or less at a density of 10 or more per 100 μm along the rotation axis direction (longitudinal direction).

In the rubbing mode, when refresh roller 120 rubs and a large number of fine rubbing scratches are formed on the entire surface (peripheral surface) of fixing belt 106, the surface of fixing belt 106 is repaired. That is, there is no unevenness difference between (I) the paper passing portion, (II) the paper non-passing portion, and (III) the paper edge portion which is the boundary area in FIG.

As a result, the unevenness of the surface of the fixing belt 106 is reduced to a level at which the gloss difference on the transferred fixed image cannot be visually recognized, and scratches on the fixing belt 106 also become difficult to visually recognize on the output image. In addition, the low-gloss streaks in the paper edge portion, which is the (III) boundary area of the fixed image, are almost eliminated, and the gloss step between the (I) paper-passing portion and (II) non-paper-passing portion of the fixed image is also eliminated. become inconspicuous.

(rubbing mode)
Next, the rubbing mode (refresh operation) of this embodiment will be described using the block diagram of FIG. The motor 92 a is a motor for rotating the pressure roller 101 , whereby the fixing belt 106 is driven to rotate with respect to the pressure roller 101 . On the other hand, the motor 92b is a motor that drives the refreshing roller 120 to rotate.

In the rubbing mode, the motors 92a and 92b provide a predetermined relative speed difference between the fixing belt 106 and the refreshing roller 120. FIG. The motor 92b connects the driving train with the refreshing roller 120 by a gear (not shown). The motor control unit 91 controls the rotation/stop of the refreshing roller 120 by controlling the motor 92b. The refreshing roller 120 may have a relative speed in the same direction as the moving direction of the surface of the fixing belt 106 or may have a relative speed difference in the opposite direction.

The rubbing mode is executed when the number of sheets on which toner images are formed by the image forming section (the number of sheets formed with images) reaches a predetermined number. The image forming apparatus 100 has a counter that counts a value corresponding to the number of images formed, and executes the rubbing mode when the counted value reaches a predetermined value. In this embodiment, when the predetermined number of sheets (predetermined number of times) is reached during the image forming job, the motor control section 91 waits until the image forming job is completed and starts the rubbing mode.

Note that the values corresponding to the number of image formations include the number of image formations, the number of sheets subjected to fixing processing, the number of times fixing processing was performed, the time during which the image forming operation was performed on the sheets, and the number of times the fixing processing was performed on the sheets. Including the time it was executed, etc.

Further, when the predetermined number of sheets (predetermined number of times) is reached during the image forming job, the motor control section 91 may interrupt the image forming job and start the rubbing mode. Further, the rubbing mode may be executed in response to the operator inputting an instruction to execute the rubbing mode from the operation unit or the input device.

(Flow including temperature control of fixing belt during image formation)
FIG. 6 is a flowchart including temperature control of the fixing belt 106 during image formation in the fixing device 9 as the fixing device of this embodiment. FIG. 7 is a flowchart for explaining control when the pressure roller 101 is at a high temperature. First, description will be made in the order of the reference numerals shown in FIG.

(S01) When the print operation is set, the CPU 81 (FIG. 5) first determines whether the fixing device is in a printable state, that is, in a standby state. If so, the pressurizing operation is performed. Also, in the post-printing rotation operation or in the rubbing mode, which will be described later, it is confirmed that the fixing device 9 is put into a standby state after the processing is completed.

(S02) In the standby state, the CPU 81 starts the temperature control operation of the heater 102 (FIG. 1) by the heater control section 90 (FIG. 5) as a control section for controlling the temperature of the heating rotor.

(S03) At this time, the temperature detection unit 89 (Fig. 5) continuously monitors the temperature of the thermistor 42a (Fig. 5) that detects the temperature of the fixing belt 106, and controls the detected temperature to T1 [°C]. do. The thermistor 42a may be provided in contact with the inner surface of the fixing belt 106, or may indirectly detect the temperature of the fixing belt 106 by contacting the heater including the heater 102 and detecting the temperature of the heater. may be configured. Also, the thermistor 42a may be of a contact type or a non-contact type. In either case, it functions as a detection unit that detects the temperature of the fixing belt 106 . T1 [° C.] is the target temperature for temperature control of the heater in the standby state.

(S04) After confirming that the heater 102 is turned on, the CPU 81 causes the motor control unit 91 (FIG. 5) to operate the motor 92a to start rotating the pressure roller 101 (FIG. 2). As the fixing belt 106 (FIG. 2) is driven to rotate by the pressure roller 101, the heat from the heater 102 is transmitted to the entire fixing belt.

(S05 to S08) After that, when it is confirmed that the detected temperature T [°C] is equal to or higher than the temperature control target temperature T1 [°C], the heater control unit 90 sets the temperature to T2 [°C] corresponding to the print temperature of the sheet P. Sets the target temperature (temperature control temperature) for image formation. If the detected temperature T [° C.] exceeds T2 [° C.] even once, it is determined that printing is possible, and the sheet P can be conveyed to the fixing device 9 (printing permitted). It should be noted that the rising detected temperature T may be predicted in advance, and the feeding of the sheet P and the image formation may be performed in advance.

In this embodiment, the temperature control target temperature T2 [°C] is set lower than the temperature control target temperature T1 [°C] of the heater in the standby state. It may be set higher than the target temperature T1 [° C.] for temperature control of the heater in the state.

(S09) The fixing device 9 continues rotation of the fixing member and heater temperature control until the printing operation is completed.

(S10) After the printing operation is completed, the heating of the heater 102 is interrupted, and the driving of the heating member is also stopped.

(S11) With the above series of operations, the normal print operation flow is completed. After a certain period of time has elapsed, the pressure roller 101 serving as a pressure member is operated to release the pressure, thereby reducing the force applied to the fixing belt 106 .

Next, referring to FIG. 7, the printing operation when the temperature rise of the pressure roller 101 (FIG. 1) is detected will be described. When the pressure roller 101 transmits the drive to the fixing belt 106, it is common to set the temperature control temperature on the fixing belt 106 side high and the temperature on the pressure roller 101 side relatively low. In particular, when printing on the second side, heat from the pressure roller 101 is also received under the condition that the toner image is placed on the pressure roller 101 side.

For this reason, when the surface temperature of the pressure roller 101 is about 100° C., which is the softening temperature of the toner, problems such as high-temperature toner offset and excessive heating of the sheet P may cause problems such as curling. For this reason, the print job may not be performed or be suspended until the temperature of the pressure roller 101 drops below a certain level due to cooling.

FIG. 8 is an explanatory diagram showing adverse effects when the temperature of the pressure roller rises (showing that there are cases where the relationship between the temperatures of the fixing belt and the pressure roller during image formation is appropriate and there are cases where it is inappropriate). This is when CS-680, which has a basis weight of plain paper of 68 g/cm2, is used.

In FIG. 8, if the temperature of the fixing belt during image formation is lower than the proper temperature range, the toner fixability cannot be ensured (toner fixability NG). On the other hand, if the temperature of the fixing belt is higher than the proper temperature range, the surface of the toner will be in a super-melted state, causing a high-temperature offset in which the toner is not fixed on the sheet P, and the curl amount of the recording paper may increase. In FIG. 8, when the temperature of the pressure roller, which affects the fixability of the toner, exceeds about 100 [° C.], the temperature range of the fixing belt 106 in which proper fixing is possible is narrowed.

When the temperature of the pressure roller 101 is raised, the temperature U of the pressure roller as a pressure member is set to a predetermined value U1 or less so that the print job is not performed until the temperature of the pressure roller 101 drops below a certain level. FIG. 7 shows the case of performing control during formation. The only difference from the flow of FIG. 6 is the control of S23. This is obtained by adding the temperature condition of the pressure roller to the condition for starting fixing. Other than that, the control is the same.

In order to detect the temperature of the pressure roller 101 as a pressure member in S23 of FIG. 7, for example, the thermistor 42b is arranged at a position 100 mm away from the center position of the pressure roller 101 in the longitudinal direction. Then, the surface layer of the pressure roller 101 is measured by the thermistor 42b. Hereinafter, description will be made in the order of the reference numerals shown in FIG.

(S21) When the print operation is set, it is first determined whether the fixing device is in a printable state, that is, in a standby state. conduct. Also, in the case of the post-printing rotation operation or the rubbing mode, which will be described later, it is confirmed that the processing is completed and the fixing device is put into the standby state.

(S22) If it is in the standby state, the heater controller 90 starts the temperature control operation of the heater 102 .

(S23) It is determined that the temperature of the pressure roller 101 is below the printable threshold. Here, U1 is set to 100[° C.], and the condition for starting the next print is that the surface temperature U of the pressure roller 101 detected by the thermistor 42b is equal to or lower than U1. In this case, a good fixing operation can be performed by setting the temperature control temperature of the fixing belt 106 to 150.degree. Further, it is not always necessary to dispose a temperature detection member here. For example, if the temperature of the pressure roller 101 can be predicted from the past history, the predicted value may be used for control.

(S24) At this time, the temperature of the thermistor 42a that detects the temperature of the fixing belt 106 is continuously monitored by the temperature detector 89 (FIG. 5), and the detected temperature is controlled to be T1 [° C.]. T1 [°C] is the target temperature (controlled temperature) of the heater in the standby state.

(S25) When it is confirmed that the heater 102 is turned on, the motor controller 91 operates the motor 92a to start rotating the pressure roller 101. FIG. As the fixing belt rotates following the pressure roller, heat from the heater 102 is transmitted to the entire fixing belt.

(S26) After that, when it is confirmed that the detected temperature T [°C] is equal to or higher than the temperature control target temperature T1 [°C], the temperature control target temperature is set to T2 [°C] corresponding to the printing temperature of the sheet P. . If T [° C.] exceeds T2 [° C.] even once, it is determined that printing is possible, and the sheet P can be conveyed to the fixing device. Alternatively, the rising temperature T may be predicted in advance, and the feeding of the sheet P and the image formation may be performed in advance.

In this embodiment, the temperature control target temperature T2 [°C] is set lower than the temperature control target temperature T1 [°C] of the heater in the standby state. It may be set higher than the target temperature T1 [° C.] for temperature control of the heater in the state.

(S27) The fixing device 9 continues rotation of the fixing member and heater temperature control until the printing operation is completed.

(S28) After the printing operation is completed, the heating of the heater 102 is interrupted, and the driving of the heating member is also stopped.

(S29) With the above series of operations, the normal print operation flow is completed. After a certain period of time has elapsed, the pressure roller 101 serving as a pressure member is operated to release the pressure, thereby reducing the force applied to the fixing belt 106 .

(Flow of rubbing mode including temperature control of fixing belt during rubbing processing)
Hereinafter, in the rubbing mode including the temperature control of the fixing belt during the rubbing process, in the printing operation after the rubbing process using the refresh roller 120, the problem due to the temperature rise of the pressure roller 101 is prevented. The flow of this embodiment will be described with reference to FIG.

(S41) A refresh operation is started in the rubbing mode.

(S42) It is determined whether or not the fixing device 9 is in the standby state, and if it is in the image forming state or the maintenance state, it waits until it enters the standby state. In this rubbing mode, the pressure roller 101 is driven to rotate and the fixing belt 106 is driven to rotate. In the configuration of the present embodiment, since the fixing belt 106 is rotated by the pressure roller 101, the fixing belt 106 and the pressure roller 101 are pressed to perform the rubbing mode. In the rubbing mode, the heater 102 is turned on to heat the fixing belt 106 to a predetermined temperature. Specifically, it is shown in the following flow.

(S43) The heater 102 is set to the initial controlled temperature T1 [°C], and at the same time (S44) the pressure roller 101 starts rotating.

(S45) Confirm that the target temperature of the fixing belt 106 has reached T1 [°C].

(S46) After that, pressurization of the refreshing roller 106 is started. When the actuator is released, the refreshing roller 120 is urged by the pressure spring to abut against the fixing belt 106 with a predetermined pressure, and is sandwiched by the inner refreshing backup member 121 (FIG. 1). Thereby, a rubbing portion having a predetermined width in the rotation direction of the fixing belt 106 is formed.

In the rubbing mode, the fixing belt 106 rotates at a normal peripheral speed for image formation, but it is desirable that the refreshing roller 120 rotates with a peripheral speed difference from the fixing belt 106 . The motor control unit 91 operates the motor 92b to rotate the refreshing roller 120 with respect to the fixing belt 106 with a predetermined peripheral speed difference.

(S47) The temperature control temperature during this rubbing operation is T3 [°C]. It is set lower than the temperature T2 [°C]. As a result, the temperature rise of the pressure roller 101 can be suppressed in the printing operation (S50) after the rubbing process. As a result, the waiting time for cooling the pressure roller during the next image forming operation (or when resuming the image forming operation) can be reduced, thereby improving productivity. When the temperature of the fixing belt 106 is higher than T3[°C], such as immediately after the image forming operation, the refreshing roller 120 starts rubbing without waiting for the temperature to drop to T3[°C]. good too.

(S48) The motor control unit 91 executes the rubbing mode for the required time P1 [sec]. Here, the time is determined according to the total number of sheets passed until the rubbing mode is executed.

(S49) After the actuator is operated to separate the refreshing roller 120 from the fixing belt 106, the motor 92b is stopped to stop the rotation of the refreshing roller 120.

(S50) When the rubbing mode ends, the motor control section 91 shifts to the image forming state again.

(Effect of Heating of Fixing Belt in Sliding Mode)
In the rubbing mode, the heating operation is performed as described above before the refreshing roller 120 comes into contact with the fixing belt 106 (S43 in FIG. 7). The first purpose of this heating operation is for stable rotation of the fixing belt 106 . This is because if the material such as silicone rubber in the fixing belt 106 is close to normal temperature, it is hard and thus is difficult to deform when the fixing belt 106 rotates. Therefore, if the fixing belt is not heated in the rubbing mode, the contact surface area and pressure of the refreshing roller 120 contacting the fixing belt 106 may not be stable.

As a second purpose of the heating operation, when the fixing belt is not heated and is below the softening temperature of the grease on the inner surface of the fixing belt, the frictional force between the inner surface of the fixing belt 106 and the sliding surface of the heater 102 is high. As a result, the driving torque increases and the members are scraped off. Therefore, it is desirable to rotate the fixing belt while heating it to a certain temperature or higher. However, there are cases where the application of grease is not necessary, and there are cases where a substance such as oil that has the effect of lowering the slidability even at room temperature is used. Not that.

A third purpose of the heating operation is to soften the release layer of the fixing belt 106 and enhance the rubbing effect. FIG. 10 shows the relationship between the temperature and the hardness of the PFA resin. At 150° C. and at 30° C., there is a difference between 40 and 58 in Shore hardness as hardness of the fixing belt 106 . For this reason, the higher the temperature, the softer the material, thereby enhancing the rubbing effect.

(Sliding Effect Accompanied by Heater Temperature Control in Sliding Mode of the Present Embodiment)
Here, in this embodiment in which the temperature control temperature T3 [° C.] in the rubbing mode is set lower than the temperature control temperature T2 [° C.] during printing, the higher temperature is slightly better, but the rubbing effect is I made sure there was enough.

(Configuration and effect of the present embodiment regarding target temperature)
In this embodiment, the control unit that controls the temperature of the heating rotator can set the target temperature of the heating rotator during the fixing operation to a plurality of target temperatures including the lowest first target temperature. The temperature of the heating rotator is controlled so that the temperature of the heating rotator becomes one of the plurality of target temperatures during the fixing operation of heating the unfixed toner image on the recording material at the fixing nip portion. do. Then, during the execution of the rubbing action by the rubbing member which is executed with the rubbing member positioned at the contact position, the temperature of the heating rotor is equal to or lower than the first target temperature, which is the lowest among the plurality of target temperatures. The temperature of the heating rotor is controlled so as to reach the second target temperature, which is the temperature of .

Conventionally, the temperature of the fixing member is controlled and rubbed at a temperature higher than the lowest of the target temperatures for printing. For this reason, in the present embodiment, the temperature of the fixing member is controlled and rubbed at a target temperature equal to or lower than the lowest target temperature during printing.

FIG. 11 shows the temperature of the fixing belt 106 when the surface temperature of the fixing belt 106 is 150° C. during non-printing (during rubbing) as a comparative example, and when the surface temperature of the fixing belt 106 is set to 150° C. during non-printing (during rubbing) as in the present embodiment. It is comparative data when the surface temperature is suppressed to 80°C. Here, both are common in that the surface temperature of the fixing belt 106 is adjusted to 150° C. during printing.

During non-printing (during rubbing), there is no paper in the fixing nip portion, and the heat on the surface of the fixing belt 106 is always directly transmitted to the pressure roller 101 along with the rotation time. Also, there is no effect of the low-temperature paper taking heat from the surface of the pressure roller 101 . Therefore, if the rubbing action is continued for 30 to 60 seconds, which is the standard time for the rubbing action, a problem may occur due to excessive temperature rise of the pressure roller 101 when printing is immediately performed thereafter.

More specifically, in the case of the conventional temperature control temperature during the rubbing action, the surface temperature of the pressure roller 101 exceeds 130° C. when the rubbing action is performed for 60 seconds. For this reason, it is necessary to cool this to less than 100° C., which is the printable temperature. In this case, as shown in the flow (S31) of FIG. 9, it takes a long time to wait for the member to be cooled, resulting in a decrease in productivity.

On the other hand, in the present embodiment, the temperature control temperature during the rubbing action is suppressed to 80.degree. Therefore, the extra time for cooling the pressure roller can be reduced for subsequent print jobs.

As described above, according to the present embodiment, it is possible to perform a highly glossy and uniform fixing operation on the sheet P, which has the advantage of improving the quality of the product and improving the durable life of the fixing member. While maintaining this, the target temperature (temperature control temperature) for temperature control of the fixing belt is kept lower during the rubbing operation than during image formation. Note that the time of image formation is also the time of fixing processing in which the toner image on the sheet is fixed by the fixing belt 106 . As a result, the print operation can be started immediately after the refresh operation, thereby improving productivity. In addition, the heat effect on the surrounding members can be minimized, which has the effect of saving energy and suppressing the temperature rise inside the machine.

In the configuration of the fixing device of this embodiment, as shown in Table 1, the temperature control temperature during image formation has a plurality of steps between 140° C. and 180° C., and is set according to the conditions of the sheet to be printed. ing.

On the other hand, the target temperature during execution of the rubbing mode is set to a temperature that is lower than any of the target temperatures during image formation or is the same as the lowest temperature among the target temperatures during image formation. The temperature control circuit controls energization to the heater so as to achieve a set target temperature in the rubbing mode. That is, in the case of the example of Table 1, the target temperature in the rubbing mode is set to 140° C. or lower, which is the lowest target temperature among the target temperatures used during image formation. More preferably, the target temperature during execution of the rubbing mode is set to a temperature lower than any of the target temperatures during image formation.

This is for the following reasons. In the rubbing mode, the heat of the fixing belt 106 is transmitted to the pressure roller 101 because the fixing belt 106 and the pressure roller 101 rotate while forming a nip portion without passing the sheet through the nip portion. However, by setting the target temperature in the rubbing mode lower than that during image formation, it is possible to suppress excessive temperature rise of the pressure roller 101 .

Further, it is more preferable to set the target temperature of the fixing belt 106 in the rubbing mode to 60° C. or more and 110° C. or less. Specifically, in order to be able to quickly start the next image forming process after the rubbing mode, the temperature of the pressure roller 101 is set at a temperature at which uneven glossiness of the image due to the temperature rise of the pressure roller 101 is less likely to occur. It is more preferable if the temperature can be maintained below a certain 100°C. Therefore, it is more preferable to set the target temperature of the fixing belt 106 in the rubbing mode at 110° C. or less. Also, the lower limit of the target temperature of the fixing belt 106 in the rubbing mode may be a level that does not impede the rotation of the fixing belt 106, and is more preferably 60° C. or higher.

(Modification)
Although preferred embodiments of the present invention have been described in the above-described embodiments, the present invention is not limited thereto, and various modifications are possible within the scope of the present invention. With regard to the system that performs the rubbing operation of the rotatable fixing member and controls the temperature, part or all of the configuration of the above-described embodiment can be replaced with an alternative configuration. . In addition, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the above embodiments are not intended to limit the scope of the present invention. do not have.

(Modification 1)
In the above-described embodiments, a film-shaped fixing belt has been described as a rotatable fixing member. Adopting the fixing belt 106 having a relatively small heat capacity with respect to the fixing roller can reduce the influence on FCOT (first copy out time). Even if the regulated temperature of the fixing belt 106 during the refresh operation is lower than that during image formation, when the image formation operation is resumed (or the next image formation operation is started) after the refresh operation, the temperature regulated temperature during image formation is reached. This is because the time required for recovery is short.

However, as a rotatable fixing member, a fixing roller in which an elastic layer is provided on the outer periphery of a metal core can be similarly applied. That is, when the fixing roller rotates and the fixing roller contacts the opposing member at the nip portion without the recording material interposed therebetween, the target temperature is set to may be set lower than during image formation facing the .

Further, in the above-described embodiment, the rotatable fixing member is driven to rotate by the pressure roller, but the rotatable fixing member may have a drive source and be driven to rotate.

(Modification 2)
Further, in the above-described embodiment, the case where the temperature control temperature (target temperature) in the rubbing mode is maintained at T3[°C. That is, in the second half or final stage of the rubbing mode, the target temperature may be changed to the target temperature for image formation (printing temperature). For example, it is for starting the next image forming process. Even with such a configuration, excessive temperature rise of the pressure roller 101 in the rubbing mode can be suppressed.

Note that if there is no next image forming job to be executed (restarted) in the rubbing mode, that is, if the transition is made to a waiting state for waiting for input of the next image forming job after execution of the rubbing mode, , as in the embodiment described above. That is, in the latter half of the rubbing mode, the temperature control temperature is not raised to the target temperature for image formation, but is set to the temperature control temperature (target temperature) in the rubbing mode even in the latter half of the rubbing mode.

(Modification 3)
Further, in the above-described embodiment, it is assumed that the refreshing roller 120 is driven by a dedicated driving means, but the present invention is not limited to this. A driving force may be transmitted from the driving means of the pressure roller 101 so that the refreshing roller 120 is rotationally driven with a peripheral speed difference with respect to the fixing belt 106 by the driving gear. Further, by connecting the pressure roller 101 and the refreshing roller 120 with a gear train having a gear ratio of 1:2, the refreshing roller 120 may be rotated at a circumferential speed twice as high as the surface speed of the fixing belt 106 .

In addition, the refreshing roller 120 as a rubbing member has been described using a rotatable structure (rubbing rotating body), but the present invention is not limited to this, and may be fixed (non-rotating). .

(Modification 4)
In the above-described embodiment, of the first rotating body and the second rotating body forming the fixing nip portion, the endless belt is provided for the first rotating body. It may be provided on both the rotating body and the second rotating body.

As described above, the pressure roller 101 as a facing member that faces the rotatable fixing member described above is not limited to a roller member, and may be a belt member.

(Modification 5)
In the above-described embodiment, the position where the refreshing roller 120 contacts the surface of the fixing film when viewed from the longitudinal direction of the fixing belt is a position displaced by 90 degrees from the central position of the fixing nip portion. is not limited to That is, when viewed from the longitudinal direction of the fixing belt, the position where the roughening roller 120 abuts on the surface of the fixing belt may be a side position displaced by a predetermined angle from the central position of the fixing nip portion.

(Modification 6)
In the above-described embodiments, the ceramic heater is used as the heating member that heats the nip portion via the rotatable fixing member, but the present invention is not limited to this. For example, it may be a halogen heater. Further, for example, the rotatable fixing member may generate heat (heat generating rotating body) by electromagnetic induction using a coil (exciting coil) that generates induction heat or by energization.

(Modification 7)
In the above-described embodiment, the sheet P as the recording material on which the toner image is formed is plain paper, thick paper, or thin paper, but is not limited to this. For example, standard or irregular size envelopes, postcards, stickers, resin sheets, OHP sheets, glossy paper and the like are included. In the above-described embodiment, the handling of the recording material (sheet) P is described using terms such as paper for convenience, but the recording material in the present invention is not limited to paper.

(Modification 8)
In the above-described embodiments, an apparatus that fixes an unfixed toner image on a sheet is described as an example, but the present invention is not limited to this. The present invention can also be applied to a device that heats and presses a toner image preliminarily adhered to a sheet (this case is also referred to as a fixing device in this specification) in order to improve the glossiness of the image.

90 heater control unit 101 pressure roller 102 heater 106 fixing belt 120 refresh roller

Claims (9)

a heating rotator that heats the toner image while being in contact with the unfixed toner image on the recording material at the fixing nip;
a counter rotating body that cooperates with the heating rotating body to form the fixing nip;
a driving source that rotationally drives the opposing rotating body;
a rubbing member that rubs against the outer peripheral surface of the heating rotor;
A moving mechanism for moving the rubbing member so as to obtain a contact position where the rubbing member and the heating rotator abut and a separated position where the rubbing member and the heating rotator are separated from each other. When,
a control unit for controlling the temperature of the heating rotor;
and wherein the heating rotator is configured to be driven to rotate by the counter rotator,
The control unit
The target temperature of the heating rotator during the fixing operation can be set to a plurality of target temperatures including the lowest first target temperature,
During execution of a fixing operation for heating an unfixed toner image on a recording material at the fixing nip portion, the temperature of the heating rotator is adjusted so that the temperature of the heating rotator is one of the plurality of target temperatures. control and
While the rubbing member is positioned at the contact position and the heating rotor is driven to rotate by the opposing rotor, the rubbing member performs the rubbing operation, and the temperature of the heating rotor increases. The fixing device controls the temperature of the heating rotator so as to achieve a second target temperature that is equal to or lower than the first target temperature, which is the lowest among the plurality of target temperatures. 2. The fixing device according to claim 1, wherein the heating rotator and the opposing rotator form the fixing nip portion during execution of the rubbing action. 3. The fixing device according to claim 1, wherein the heating rotating member is an endless belt. a detection unit that detects the temperature of the heating rotor;
a heater for heating the heating rotating body;
has
4. The fixing device according to claim 1 , wherein the controller controls energization of the heater based on the output of the detector. a detection unit that detects the temperature of the heating rotor,
The heating rotating body is a heating rotating body that generates heat when energized,
4. The fixing device according to claim 1 , wherein the controller controls energization of the heating rotator based on the output of the detector. a detection unit that detects the temperature of the heating rotor;
a coil that causes the heating rotating body to generate heat by induction;
4. The fixing device according to claim 1 , wherein the controller controls energization of the coil based on the output of the detector. 7. The fixing device according to claim 1 , wherein the second target temperature is lower than the first target temperature. 8. The fixing device according to claim 1 , wherein the rubbing member is a rubbing rotating member. The fixing device according to any one of claims 1 to 8 , wherein the rubbing operation is performed during an interrupt operation after completion of a print job or during a manual operation in a user mode.

Images