JP2014178633A - Fixing device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of controlling a rotation speed on the basis of torque information, so as to apply an optimal conveyance force to paper.SOLUTION: A fixing device sets a rotation speed of a motor that drives a pressure roller 4 to be lower as a reduction in torque in unit time is larger, on the basis of a torque measurement value obtained by detecting driving torque of the pressure roller 4, and thereby ensures a conveyance force when paper slips to prevent the occurrence of paper jam. When the fixing device determines, with paper jam detection control means, that a reduction in motor rotation torque during paper feed is due to the slip of paper, changes a control amount according to an image area ratio on the paper and a toner input amount to apply an optimal conveyance force to the paper. The fixing device further controls the toner input amount during the slip of paper by controlling a developing bias and/or a charging bias, and thereby controlling a coefficient of friction on the surface of the paper to reduce the slip of paper.

Description

  The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a facsimile machine, a printer, and a multifunction machine thereof, and a fixing device that includes an endless fixing member and a pressure member to perform a fixing process, and the fixing device. The present invention relates to an image forming apparatus equipped with.

  In recent years, market demands for energy saving and high speed have been increasing for image forming apparatuses such as printers and copiers. In an image forming apparatus, an unfixed toner image is transferred to a recording material sheet, printing paper, photosensitive paper, electrostatic recording paper, etc. by an image transfer method or a direct method by an image forming process such as electrophotographic recording, electrostatic recording, and magnetic recording. Formed on recording material. As a fixing device for fixing an unfixed toner image, a contact heating method fixing device such as a heat roller method, a film heating method, and an electromagnetic induction heating method is widely used.

  More specifically, regarding a fixing device used in an electrostatic recording image forming apparatus, a nip is formed between an endless fixing member and a pressure member, and a fixing process is performed on a fixing material passing through the nip. A fixing device and the fixing device are mounted.

  As examples of such a fixing device, a belt-type fixing device (for example, see Patent Document 1) and a surf fixing (film fixing) fixing device (for example, see Patent Document 2) using a ceramic heater are known.

  In the belt-type fixing device, as a first problem in recent years, further warm-up time (time required from normal temperature to a predetermined printable temperature (reload temperature) such as when the power is turned on) and first print time (printing) After receiving the request, it is desired to shorten the time until the printing operation is performed after the print preparation and the paper discharge is completed. As a second problem, the number of sheets passed per unit time increases and the required heat amount increases as the speed of the image forming apparatus increases, so that the amount of heat is insufficient particularly at the beginning of continuous printing (so-called temperature drop). Is a problem.

  As a method for solving the first problem, surf fixing using a ceramic heater has been proposed, and this method enables a reduction in heat capacity and a reduction in size as compared with a belt-type fixing device. However, in this method, since only the nip portion is locally heated, the other portions are not heated. Therefore, there is a problem that the belt is in the coldest state at the entrance of the sheet or the like of the nip, and a fixing defect is likely to occur. In particular, in a high-speed machine (because the rotation of the belt is fast and the heat radiation of the belt outside the nip portion increases), there is a third problem that fixing failure is more likely to occur.

  In order to solve the first to third problems as described above, in the configuration using an endless belt, it is possible to warm the whole belt, to shorten the first print time from the heating standby time, and There has been proposed a fixing device that solves the shortage of heat at the time of high-speed rotation and can obtain good fixability even when mounted on a high-production image forming apparatus (see, for example, Patent Document 3).

  FIG. 1 is a schematic view of a fixing device described in Patent Document 3. A pipe-shaped metal heat conductor 2 is fixed inside the endless belt 1 so as to be able to guide the movement of the endless belt 1, and endlessly passed through the metal heat conductor 2 by a heat source 3 in the metal heat conductor 2. The belt 1 is heated. Further, a pressure roller 4 that forms a nip portion N in contact with the metal heat conductor 2 via the endless belt 1 is provided, and the endless belt 1 is moved in the circumferential direction so as to rotate as the pressure roller 4 rotates. Let With this configuration, it is possible to warm the entire endless belt constituting the fixing device, to shorten the first print time from the heating standby time, and to solve the shortage of heat during high-speed rotation. Yes. In the figure, 4a is a metal roller constituting the pressure roller 4, and 4b is an elastic layer.

  However, it is necessary to further improve the thermal efficiency in order to further improve the energy saving and the first print time. From the configuration in which the endless belt is indirectly heated via the metal heat conductor, the endless belt (metal heat conductor) A direct heating arrangement has been proposed. In this configuration, it is possible to reduce the power consumption by greatly improving the heat transfer efficiency and to further shorten the first print time from the heating standby time. In addition, the cost can be reduced without using a metal heat conductor.

  On the other hand, in an apparatus that is required to continuously convey paper at a high speed, such as an electrophotographic image forming apparatus, it is an important problem to convey the paper accurately at regular intervals. For example, with regard to paper feeding, paper is fed at regular intervals to maintain a constant space between papers (inter-paper space), thereby improving productivity and aligning formed images. If variations in the accuracy of the paper feed interval are significant, problems occur in terms of productivity and quality of formed images.

  In the technique disclosed in Patent Document 1 as a method for reducing the variation in the sheet conveyance interval, the required time is calculated for the roller count unit that counts the number of times the sensor detects the passage of the sheet and the sheet conveyance for a predetermined number of sheets. An average of the required time calculated by the means is calculated, a slip correction coefficient is calculated based on the calculated average of the required time and the number of passes counted by the roller count means, and the slip correction coefficient is kept constant. The rotational speed of the transport motor is controlled. However, the main purpose of this technology is to reduce variations in the paper transport interval, and it is difficult to prevent jam slip torque from the average calculation time for a given number of sheets. Not mentioned.

  In the technique disclosed in Patent Document 2, the driving torque of the pressure member is detected based on the current value of the DC motor that is the driving means, and when the current value becomes lower than a certain threshold value. Therefore, it is determined that slip jam has occurred, and the control temperature of the heating body is lowered by a certain temperature to automatically discharge the slip jammed recording material. However, making the slip judgment a current value of a certain threshold value contributes to the increase in torque due to deterioration of mechanical parts such as gear wear that contributes to the increase in torque on the pressure roller shaft over time, or to paper conveyance It is impossible to determine whether the inner surface friction state of the fixing sleeve and the friction coefficient change of the pressure roller and the surface layer of the fixing sleeve. Therefore, it is insufficient as a measure against the actual slip phenomenon.

  In addition, in the technique disclosed in Patent Document 3, a configuration is provided in which a roller is provided with a grip and the load is adjusted for conveyance. However, by providing a grip portion, an increase in electric power and an increase in manufacturing cost due to an increase in a heated portion. Therefore, it is not suitable for low cost and power saving.

  The present invention has been made in view of the above-described points, and includes a fixing device intended to deal with problems in advance and the number of times a user performs jam processing by preventing slip jamming over time. An object of the present invention is to provide an image forming apparatus capable of reducing the image quality and realizing good usability.

  The fixing device according to the present invention includes a flexible endless fixing member, a heating source for heating the fixing member, a pressure member that forms a nip with the fixing member, and the inside of the fixing member. A nip forming member that faces the pressure member and forms a nip, a support member that supports the nip forming member, a pair of holding members that hold both ends of the fixing member in the axial direction, and the pressure member are rotated. A rotation drive means; and a torque measurement means for measuring a torque for rotating the pressurizing member by the rotation drive means, and the number of rotations of the rotation drive means is determined from torque information obtained by measurement by the torque measurement means. It is characterized by controlling.

  According to the present invention, it is possible to give the optimum conveying force to the paper by controlling the rotational speed from the torque information.

Explanatory drawing showing an example of a conventional fixing device Explanatory drawing which shows one Embodiment of the fixing device of this invention Explanatory drawing which shows the fixing device of another embodiment of the present invention (configuration using a plurality of heaters) The figure which shows the relationship between the number of passing sheets and the torque which drives a pressurization rotary body with a graph Graphical representation of torque transition Graphical representation of torque fluctuations for blank paper images (no toner) and solid images (with toner on the entire paper) Schematic diagram for explaining the configuration of an image forming apparatus using a fixing device according to the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention predicts a malfunction that is considered to be caused by deterioration of a mechanical component related to continuous conveyance of paper, that is, can detect in advance a sign of occurrence of a slip jam at a fixing nip portion. It is the one that paid attention. In the embodiment of the present invention, the optimum conveying force is given to the paper by controlling the rotational speed from the torque information. That is, the knowledge that there is a difference between the normal fluctuation and the reduction of the slip precursor is used for the torque reduction.

<Embodiment 1>
FIG. 2 is a block diagram showing the fixing device of the present invention. The fixing device has a pressure rotator (pressure member: pressure roller 4 in the case of FIG. 2) and a fixing belt 1 as an endless fixing member, and a heat source 3 (halogen heater in the example of FIG. 2). The fixing belt 1 is directly heated by radiant heat from the inner peripheral side. At this time, in the fixing belt 1 of FIG. 2, a nip forming member 6 that forms a nip with a pressure roller 4 (the electric motor that is a rotation driving means is not shown) opposed via the fixing belt 1. There is. Then, it slides directly on the inner surface of the fixing belt (or indirectly through a sliding sheet (not shown)).

  In FIG. 2, the nip portion N has a flat shape, but may have a concave shape or other shapes. (When the nip shape is concave, the discharge direction of the leading end of the recording paper is closer to the pressure roller 4 and the separability is improved, so that the occurrence of jamming, that is, paper jam is suppressed.)

  The fixing belt 1 is a metal belt such as nickel or SUS or an endless belt (or film) using a resin material such as polyimide. The surface layer of the belt has a release layer such as a PFA or PTFE layer, and has a release property so that toner does not adhere. There may be an elastic layer formed of a silicone rubber layer or the like between the belt substrate and the PFA or PTFE layer. When there is no silicone rubber layer, the heat capacity is reduced and the fixability is improved, but when the unfixed image is crushed and fixed, minute irregularities on the belt surface are transferred to the image, and the image has a crusty skin shape. There arises a problem that the gloss unevenness (zudder skin image) remains. In order to improve this, it is necessary to provide a silicone rubber layer of 100 [μm] or more. Due to the deformation of the silicone rubber layer, fine irregularities are absorbed and the skin image is improved.

  A support member 7 (stay) for supporting the nip portion is provided inside the fixing belt 1 to prevent the nip forming member 6 that receives pressure from the pressure roller from being bent and to obtain a uniform nip width in the axial direction. I am doing so. The support member 7 is held and fixed by a pair of holding members 8 (flange) at both ends. Further, the reflection member 9 is provided between the heat source 3 and the support member 7, and wasteful energy consumption due to the support member 7 being heated by radiant heat from the heat source 3 or the like is suppressed. Here, the same effect can be obtained even if the surface of the support member 7 is heat-insulated or mirror-finished instead of having the reflecting member 9.

  The heat source 3 may be the illustrated halogen heater, but may be IH, a resistance heating element, a carbon heater, or the like. Further, the pressure roller 4 has an elastic rubber layer 4 on a core metal 5 and a release layer (PFA or PTFE layer) is provided on the surface in order to obtain releasability. The pressure roller 4 is rotated by a driving force transmitted through a gear from a driving source such as a motor provided in the image forming apparatus. The pressure roller 4 is pressed against the fixing belt 1 by a spring or the like, and has a predetermined nip width when the elastic rubber layer 4b is crushed and deformed. The pressure roller 4 may be a hollow roller, and the pressure roller 4 may have a heating source such as a halogen heater. The elastic rubber layer 4 may be solid rubber, but if there is no heater inside the pressure roller 4, sponge rubber may be used. Sponge rubber is more desirable because it increases heat insulation and makes it difficult for the fixing belt 1 to lose heat.

  The fixing belt 1 is rotated by the pressure roller 4. In the case of FIG. 2, the pressure roller 4 is rotated by a driving source (not shown), and the driving force is transmitted to the belt at the nip portion N, whereby the fixing belt 1 is rotated. The fixing belt 1 is sandwiched and rotated at the nip portion N, and travels while being guided by the holding member 8 (flange) at both ends other than the nip portion.

  With the above configuration, it is possible to realize a fixing device that is inexpensive and has a fast warm-up.

<Embodiment 2>
FIG. 3 is a block diagram showing another embodiment of the fixing device of the present invention. In the embodiment of FIG. 2, the heat source 3 is composed of one halogen heater, whereas the present embodiment is different in that the heat source 3 is composed of three halogen heaters.

  The fixing device includes a pressure rotator (pressure roller 4 in the case of FIG. 2) and a flexible fixing belt 1, and the fixing belt 1 is moved by a heat source 3 (halogen heater in the example of FIG. 2). An embodiment of a configuration that is directly heated by radiant heat from the circumferential side will be described.

  FIG. 4 is a graph showing the relationship between the number of sheets passed and the torque for driving the pressure rotator, and FIG. 5 is a graph showing the transition of the torque. FIG. 5 is a plot of the state of torque before and after the fixing device stands up and passes the paper. In general, the torque increases in proportion to the increase in the rotational speed of the motor, the sheet passing is started, and when the sheet is conveyed, the reaction force at the time of conveying the paper is added to the axial rotation torque of the pressure roller 4, The torque increases slightly.

  However, as shown in FIG. 4, when the oil applied to the inner surface of the fixing belt 1 is depleted over time and the frictional resistance of the fixing belt 1 is increased and the torque is increased, the paper is changed to a certain value. May cause jamming due to a slip phenomenon that is not sent at the linear speed. At that time, the torque at the moment of slipping sharply decreases as shown in FIG. This is a phenomenon in which, when the torque cannot be transmitted to the paper due to an increase in the friction load, the torque suddenly decreases in a state where the friction state changes from static friction to dynamic friction and idles. Such a slip phenomenon can be prevented by performing feedback control as the motor rotation speed as the torque decrease is large, based on the predicted torque increase over time and the steady-state torque measurement value obtained immediately before passing the paper. Is possible.

  FIG. 6 is a graph showing torque fluctuations of a blank paper image (without toner) and a solid image (with toner throughout the paper). In the case of a blank image, the torque is the same as that in the case where no slip occurs, and a slight increase in torque is observed when the paper is passed, whereas in the case of a solid image, the torque decreases abruptly as seen in the slip phenomenon. ing. This indicates that the friction coefficient of the paper surface changes depending on the state of the image printed on the paper and contributes to the slip phenomenon. By changing the image area ratio and toner input amount of the paper, the optimal friction coefficient Can be applied to the paper. At that time, by controlling the developing bias and / or the charging bias of the toner input amount according to the fluctuation of the torque, it is possible to prevent the slip even when various image passing.

  When it is difficult to estimate the friction coefficient or force that changes as the friction load on the fixing belt 1 or the sliding sheet as described above, the DC motor torque has a monotonically increasing relationship with the motor current. Therefore, the torque of the motor can be detected by detecting the current of the motor, and the torque value during normal rotation of the pressure roller 4 when a 24 V DC motor is used is 0.1 to 0.3 N · m. As an embodiment of this configuration, a DC brushless motor (product model number: DNQ06M51W25A) manufactured by Minebea was used.

  As shown in FIG. 6, the torque of the normal fixing device increases when the power is turned on and the motor rotates at the same time as the torque increases. It has been confirmed that By applying this control at the time of passing the paper after permitting the control paper feed, for example, the torque drop at the start-up in FIG. 6 can be ignored. Abnormal image output and abnormal temperature rise can be prevented by eliminating unexpected torque control other than at the time of paper passing (such as immediately after startup or after paper passing) that occurs by detecting unnecessary torque fluctuations. .

  As described above, in the embodiment of the present invention, from the torque measurement value obtained by the torque measurement means, specifically, the motor rotation speed decreases as the torque decrease increases according to the torque decrease per unit time. Set as follows. This secures the conveyance force when the paper slips and prevents jamming. In addition, when the jam detection control means determines that the decrease in the motor rotation torque during paper feeding is slipping, the optimum conveying force is given to the paper by changing the control amount according to the image area ratio of the paper and the toner input amount. Can do. The driving torque detection means of the pressure roller 4 can accurately read the torque load by detecting the rotational driving torque based on the current value from the power source to the motor. Further, by controlling the developing bias and / or the charging bias with respect to the toner input amount at the time of slipping, the friction coefficient of the paper surface can be controlled to reduce the slip. Furthermore, by applying the control according to the present embodiment at the time of passing a sheet, an abnormal image is output by not detecting an unexpected torque fluctuation other than at the time of passing a sheet (immediately after startup, after passing a sheet, etc.). And prevents abnormal temperature rise.

<Embodiment 3>
The configuration of the image forming apparatus equipped with the fixing device according to the embodiment of the present invention described above will be described with reference to FIG.
The image forming apparatus shown in FIG. 7 is a color printer using a tandem system in which image forming units for forming a plurality of color images are juxtaposed along the belt extending direction. However, the present invention is not limited to this system. It is also possible to target not only printers but also copying machines and facsimile machines.

  In FIG. 7, an image forming apparatus 100 includes photosensitive drums 20Y, 20C, 20M as image carriers capable of forming images as images corresponding to colors separated into yellow, cyan, magenta, and black, respectively. A tandem structure with 20 Bk arranged side by side is adopted.

  In the image forming apparatus 100 configured as shown in FIG. 7, the visible images formed on the photosensitive drums 20Y, 20C, 20M, and 20Bk are collectively transferred by executing a secondary transfer process. That is, a primary transfer process is performed on an intermediate transfer body (hereinafter referred to as a transfer belt) 110 that uses an endless belt that can move in the direction of arrow A1 while facing each of the photosensitive drums 20Y, 20C, 20M, and 20Bk. The respective images are superimposed and transferred. Thereafter, the recording sheet S using the recording sheet or the like is transferred in a batch by executing a secondary transfer process.

  Around each photosensitive drum, an apparatus for image forming processing is arranged according to the rotation of the photosensitive drum. To describe the photosensitive drum 20Bk that performs black image formation, a charging device 30Bk, a developing device 40Bk, a primary transfer roller 12Bk, and a cleaning device 50Bk that perform image forming processing along the rotational direction of the photosensitive drum 20Bk are arranged. ing. For writing performed after charging, an optical writing device 81 is used.

  In the superimposing transfer to the transfer belt 110, the visible image formed on each of the photoconductive drums 20Y, 20C, 20M, and 20Bk is transferred to the same position on the transfer belt 110 while the transfer belt 110 moves in the A1 direction. To be. That is, the voltage is applied by the primary transfer rollers 12Y, 12C, 12M, and 12Bk arranged to face the respective photoconductive drums 20Y, 20C, 20M, and 20Bk with the transfer belt 110 interposed therebetween, so that the A1 direction upstream side to the downstream side. This is done at different timings. The photosensitive drums 20Y, 20C, 20M, and 20Bk are arranged in this order from the upstream side in the A1 direction. Each of the photosensitive drums 20Y, 20C, 20M, and 20Bk is provided in an image station for forming yellow, cyan, magenta, and black images, respectively.

  The image forming apparatus 100 is disposed so as to face four image stations that perform image forming processing for each color, and above the photosensitive drums 20Y, 20C, 20M, and 20Bk. Further, a transfer belt unit 10 including a transfer belt 110 and primary transfer rollers 12Y, 12C, 12M, and 12Bk is provided. Further, a secondary transfer roller 51 that is a transfer roller as a transfer member that is disposed to face the transfer belt 110 and is driven by the transfer belt 110 and a transfer belt 110 that rotates with the transfer belt 110, and a transfer belt 110 that is disposed to face the transfer belt 110. A cleaning device 13 is provided for cleaning. An optical writing device 81 serving as an optical writing device is provided below the four image stations.

  The optical writing device 81 is equipped with a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating polygon mirror as a deflecting means, and the like. Writing light Lb corresponding to each color for each of the photosensitive drums 20Y, 20C, 20M, and 20Bk (in the figure, for the sake of convenience, only the black image station is marked. For the other image stations, the same applies. And an electrostatic latent image is formed on the photosensitive drums 20Y, 20C, 20M, and 20Bk.

  The image forming apparatus 100 is provided with a sheet feeding device 61 as a paper feeding cassette on which recording sheets S transported between the photosensitive drums 20Y, 20C, 20M, and 20Bk and the transfer belt 110 are stacked. . Then, the recording sheet S conveyed from the sheet feeding device 61 by the registration roller pair 41 is transferred between the photosensitive drums 20Y to 20Bk and the transfer belt 110 at a predetermined timing in accordance with the toner image formation timing by the image station. It pays out toward the transfer part. In addition, a sensor (not shown) that detects that the leading edge of the recording sheet S has reached the registration roller pair 41 is provided.

  The image forming apparatus 100 is provided with a fixing device 120 as a roller fixing type fixing unit for fixing the toner image to the recording paper S on which the toner image is transferred. Further, a discharge roller 71 that discharges the fixed recording sheet S to the outside of the main body of the image forming apparatus 100 is provided. In addition, a paper discharge tray 17 that is disposed on the top of the main body of the image forming apparatus 100 and stacks the recording paper S that is discharged to the outside of the main body of the image forming apparatus 100 by the paper discharge roller 71, and below the paper discharge tray 17. And toner bottles 9Y to 9Bk filled with yellow, cyan, magenta, and black toners.

  The transfer belt unit 10 includes a drive roller 72 and a driven roller 73 around which the transfer belt 110 is wound, in addition to the transfer belt 110 and the primary transfer rollers 12Y, 12C, 12M, and 12Bk. The driven roller 73 also has a function as a tension urging unit for the transfer belt 110. For this reason, the driven roller 73 is provided with an urging unit using a spring or the like. Such a transfer belt unit 10, the primary transfer rollers 12Y, 12C, 12M, and 12Bk, the secondary transfer roller 51, and the cleaning device 13 constitute a transfer device 70.

  The sheet feeding device 61 is disposed at the lower part of the main body of the image forming apparatus 100 and includes a secondary transfer roller 51 as a paper feeding roller that abuts on the upper surface of the uppermost recording paper S. The secondary transfer roller 51 is driven to rotate counterclockwise, so that the uppermost recording sheet S is fed toward the registration roller pair 41.

  Although not shown in detail, the cleaning device 13 provided in the transfer device 70 has a cleaning brush and a cleaning blade disposed so as to face and contact the transfer belt 110. As a result, foreign matters such as residual toner on the transfer belt 110 are scraped and removed by the cleaning brush and the cleaning blade, and the transfer belt 110 is cleaned.

  The cleaning device 13 also has a discharge means (not shown) for carrying out and discarding the residual toner removed from the transfer belt 110.

  In the embodiment of the present invention described above, in addition to the image information in the image forming operation, the image forming operation can be changed based on the function of the printer or copying. Further, after the image forming operation is finished, the temperature condition during the image forming operation may be initialized to a default temperature condition. Alternatively, a plurality of temperature conditions may be prepared, and one of a plurality of temperature condition candidates may be selected and set based on image information in the image forming operation.

  The present invention is not limited to the embodiments described above, and many variations are possible by those having ordinary knowledge in the art within the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 1 Fixing belt 3 Heat source 4 Pressure roller 6 Nip forming member 7 Support member 8 Holding member 9 Reflecting member 10 Light shielding member 11 Temperature detection element 12 Central heater 13 End heater 14 Limited heater 100 Image forming apparatus 110 Transfer belt N Nip portion

JP 2004-286922 A Japanese Patent No. 2861280 JP 2007-334205 A

Claims (7)

An endless fixing member having flexibility;
A heating source for heating the fixing member;
A pressure member that forms a nip with the fixing member;
A nip forming member that faces the pressure member and forms a nip inside the fixing member;
A support member for supporting the nip forming member;
A pair of holding members for holding both axial ends of the fixing member;
Rotation driving means for rotating the pressure member;
Torque measuring means for measuring torque for rotating the pressure member by the rotation driving means;
With
A fixing device that controls the number of rotations of the rotation drive unit from torque information obtained by measurement by the torque measurement unit. The image forming apparatus according to claim 1.
From the torque measurement value obtained by the torque measurement means, the rotation speed of the rotation drive means is set lower as the decrease in torque per unit time is greater
A fixing device. The fixing device according to claim 1 or 2,
From the torque measurement value in the steady state obtained by the torque measuring unit immediately before the sheet passing, the rotation speed of the rotation driving unit is set to be lower as the torque decrease after the sheet feeding is started is larger.
A fixing device. The fixing device according to any one of claims 1 to 3,
Jam detection control means for detecting a paper jam between the fixing member and the pressure member,
When the jam detection control means determines that the decrease in torque of the rotation driving means during paper feeding is slipping, the control amount of the rotation speed is changed according to the image area ratio of the paper and the toner input amount to the paper.
A fixing device. The fixing device according to any one of claims 1 to 4,
The rotation driving means is an electric motor;
The torque measuring means detects rotational driving torque based on a current value to the electric motor;
A fixing device. An image forming apparatus equipped with the fixing device according to claim 1.
The toner input amount is controlled by controlling the developing bias and / or charging bias of the developing device.
An image forming apparatus. The image forming apparatus according to claim 6.
An image forming apparatus, wherein the control of the toner input amount is applied at the time of paper feeding after permitting paper feeding for control.