JP4893338B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a toner image formed on a transfer material, which is mounted on an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine having these functions, by a fixing member and a pressure member. The present invention relates to a fixing device that heats and pressurizes the image and an image forming apparatus including the fixing device.

  Conventionally, a fixing device used in an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine having these functions has a fixing roller maintained at a predetermined temperature and an elastic layer. A heat roller fixing system that heats and presses a transfer material on which a toner image is formed is sandwiched and conveyed by a fixing nip formed by a pressure roller that is in pressure contact with the fixing roller. Widely used in everything from color machines to color machines.

  The conventional heat roller fixing type fixing device is disadvantageous in terms of power saving because it is necessary to heat the fixing roller having a large heat capacity when heating the toner image on the transfer material. There is a problem that it takes time to warm up the printer and the time (warm up time) until printing starts becomes long.

  In order to solve the above problems, a belt-shaped fixing belt or a belt-shaped pressure member is used, the heat capacity is lowered by the fixing member, and a temperature-controlled heater is brought into direct pressure contact with the fixing belt to achieve heat transfer efficiency. In recent years, a belt fixing type fixing device and an image forming apparatus have been proposed and used in recent years, which greatly improve the image quality and achieve a quick start that requires little power saving and warm-up time.

  The fixing device proposed in Patent Document 1 includes a heat fixing roller having a heating source, a rotatable pressure belt that forms a fixing nip portion, a pad member that presses the pressure belt from the inside, and a lubricant. And a porous sliding member between the pressure belt and the pad member to reduce sliding resistance.

The fixing device proposed in Patent Document 2 circumscribes the pressure belt separately from the driving member that drives the fixing roller in order to make the relative speed between the fixing roller and the pressure belt constant. A pressure belt driving member is provided to drive the pressure belt from the outer surface side of the pressure belt by sandwiching the pressure belt with a belt support member inscribed in the pressure belt.
JP 2003-107936 A JP 2005-300098 A

  When an image is formed continuously on a recording material in an image forming apparatus, in a belt nip type fixing apparatus, a fixing formed between a rotating fixing rotating body (fixing roller, fixing belt) and a pressure belt. When the recording material continuously passes through the nip while holding the gap between the sheets, if the relative speed between the fixing rotator and the pressure belt fluctuates, the toner image formed on the recording material may be disturbed. .

  In the fixing device disclosed in Patent Document 1, when printing is performed for a long period of time, sliding resistance between the pressure belt and the sliding member due to wear of the pressure belt and the sliding member, exhaustion of the lubricant, and the like. Increases, slipping occurs between the pressure belt and the fixing rotator, and the pressure belt speed decreases or fluctuates.

  In the fixing device disclosed in Patent Document 2, by providing a separate pressure belt driving member independent of the fixing roller driving member, the relative speed between the fixing roller and the pressure belt can be made constant.

  However, when the fixing device is operated for a long period of time, the lubricant in the pressure belt is exhausted, the inner surface of the pressure belt and the surface of the pressure pad are worn, and the frictional powder is mixed into the lubricant. There is a problem that the sliding resistance of the pressure belt increases due to deterioration of performance, and a speed difference is generated between the fixing roller and the pressure belt.

  The present invention has been made paying attention to the above problems, and the object of the present invention is to wear the endless pressure belt or the endless fixing belt by operating the fixing device for a long period of time. Fixing device capable of ensuring stable belt travel even when the sliding resistance between the fixing roller and the endless pressure belt or the pressure roller and the endless fixing belt increases. Another object of the present invention is to provide an image forming apparatus including the fixing device.

  The above object can be achieved by the following solutions.

1. Fixing having a fixing nip portion that holds a recording material carrying a toner image between a fixing roller that is driven and rotated by a first driving source and an endless pressure belt that rotates while being pressed against the fixing roller, and that is heated and pressurized and fixed. In the apparatus, a second drive source for rotating the endless pressure belt, an integrated time measuring means for measuring an integrated time for heating and fixing the recording material carrying the toner image, and
And a second drive source output control means for increasing the output of the second drive source in accordance with the accumulated time measured by the accumulated time measuring means.

2. A fixing nip portion that sandwiches a recording material carrying a toner image by a pressure roller that is driven and rotated by a first driving source and an endless fixing belt that rotates while being pressed against the pressure roller, and that is heated and pressurized and fixed; In the fixing device, a second drive source that rotates the endless fixing belt, an integrated time measuring unit that measures an integrated time for heating and fixing the recording material carrying the toner image, and
And a second drive source output control means for increasing the output of the second drive source in accordance with the accumulated time measured by the accumulated time measuring means.

  3. Image forming means for forming a toner image on an image carrier, paper feeding means for supplying a recording material to the image forming means, transfer means for transferring the toner image to the recording material, and the transferred toner image An image forming apparatus comprising: the fixing device according to item 1 or 2 that fixes the toner onto the recording material.

  The fixing device and the image forming apparatus of the present invention can obtain the following effects by the configuration described above.

  1. Even if the sliding resistance of the endless pressure belt changes with time, the output of the second drive source that rotates the endless pressure belt is increased by a predetermined amount, so that the circumference of the endless pressure belt is increased. The speed can be kept constant.

  2. Even if the sliding resistance of the fixing belt changes with time, the peripheral speed of the endless fixing belt is kept constant by increasing the output of the second drive source that rotates the endless fixing belt by a predetermined amount. I can do it.

  3. According to the image forming apparatus provided with the fixing device of the present invention, a stable and uniform fixing process can be performed and a good image can be obtained without thermally deforming the recording material.

  Embodiments of the present invention will be described below. The description in this column does not limit the technical scope of the claims or the meaning of terms.

  FIG. 1 is a configuration diagram showing an example of an image forming apparatus according to the present invention.

  The image forming apparatus includes an image forming apparatus main body A and an image reading apparatus B.

  The image forming apparatus main body A is called a tandem color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a belt-like intermediate transfer member 6, a sheet feeding and conveying unit, a fixing device 30, and the like. Become.

  An image reading device B including an automatic document feeder DF and a document image scanning exposure device SC is installed on the upper part of the image forming apparatus main body A. The document d placed on the document table of the automatic document feeder DF is transported by a transport means, and an image on one or both sides of the document is scanned and exposed by the optical system of the document image scanning exposure device SC, and is applied to the line image sensor CCD. Is read.

  A signal formed by photoelectric conversion by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in an image processing unit, and then exposure means 3Y, 3M, 3C, 3K. Sent to.

  The image forming unit 10Y that forms a yellow (Y) toner image has a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, and a cleaning unit 8Y arranged around the photoreceptor 1Y. In the image forming unit 10M that forms a magenta (M) toner image, a charging unit 2M, an exposure unit 3M, a developing unit 4M, and a cleaning unit 8M are arranged around the photoreceptor 1M. In the image forming unit 10C for forming a cyan (C) toner image, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a cleaning unit 8C are arranged around the photoreceptor 1C. In the image forming unit 10K that forms a black (K) toner image, a charging unit 2K, an exposure unit 3K, a developing unit 4K, and a cleaning unit 8K are disposed around the photoreceptor 1K. The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure device 3C, and the charging unit 2K and the exposure device 3K constitute a latent image forming unit.

  The developing units 4Y, 4M, 4C, and 4K include a two-component developer composed of a toner having a small particle size of yellow (Y), magenta (M), cyan (C), and black (K) and a carrier.

  The intermediate transfer member 6 is wound around a plurality of rollers and is rotatably supported by a driving unit (not shown).

  The fixing device 30 heats and presses the toner image on the recording material P at a fixing nip N formed between the heated fixing roller 31 and the endless pressure belt 32 to fix the toner image.

  The toner images of the respective colors formed by the image forming units 10Y, 10M, 10C, and 10K are sequentially transferred (primary transfer) by the primary transfer units 7Y, 7M, 7C, and 7K onto the rotating intermediate transfer body 6. A toner image (hereinafter referred to as a color image) obtained by combining the color images is formed. The recording material P accommodated in the paper feeding cassette 20 is fed by the paper feeding means 21 and is conveyed to the secondary transfer means 7A through the paper feeding rollers 22A, 22B, 22C, 22D, the registration rollers 23, and the like. A color image is transferred onto the recording material P (secondary transfer). The recording material P to which the color image has been transferred is heated and pressed by the fixing device 30 to fix the color image on the recording material P. Thereafter, the sheet is sandwiched between the sheet discharge rollers 24 and placed on the sheet discharge tray 25 outside the apparatus.

  On the other hand, after the color image is transferred to the recording material P by the secondary transfer means 7A, the residual toner is removed by the cleaning means 8A from the intermediate transfer body 6 from which the recording material P is separated by curvature.

  The image forming apparatus for forming a color image has been described above. However, an image forming apparatus for forming a monochrome image may be used, or an intermediate transfer member may or may not be used.

  Next, the main configuration of the belt nip type fixing device 30 according to the present invention will be described.

  FIG. 2 is a cross-sectional view of the belt nip type fixing device 30 according to the present invention. FIG. 3 is an enlarged cross-sectional view of the fixing roller 31 and the endless pressure belt 32.

  The fixing device 30 according to an embodiment of the present invention includes a fixing roller 31 above the sheet passing path and an endless pressure belt 32 below the sheet passing path.

  In the present invention, an endless pressure belt (hereinafter simply referred to as a pressure belt) 32 includes an inlet roller 33 disposed on an inlet side for feeding a recording material P carrying a toner image to a fixing nip portion N, and a fixing nip. The belt is stretched by at least three rollers, that is, an outlet roller 34 that presses the pressure belt 32 against the fixing roller 31 and a tension roller 35 that applies tension to the pressure belt 32 at the most downstream portion of the portion N. A more excellent effect can be achieved with the configuration in which the pressing means 36 disposed inside the pressure belt 32 at N is pressed against the fixing roller 31.

  That is, since the fixing roller 31 and the pressure belt 32 are pressed and fixed over a wide area in the fixing nip portion N for a long time, the recording material P-shaped toner image can be sufficiently heated and fixed. In particular, it is advantageous when fixing a multicolor toner image, a solid image such as a picture image, an image formed on a thick recording material such as coated paper, or the like.

  In the present invention, the second drive source (motor M2) preferably rotates the pressure belt 32 by driving the outlet roller 34. This is because the fixing roller nip portion N side of the rotating belt 32 is tensioned and forcedly rotated by connecting the outlet roller 34 disposed downstream of the fixing nip portion N to a drive source and rotating it. That is why.

  A preferred embodiment of the present invention will be described below with reference to FIGS.

  A single color toner image or a multicolor toner image on the recording material P is fixed by heating and pressurizing through a fixing nip formed between the fixing roller 31 and the pressure belt 32.

  The fixing roller 31 includes a halogen lamp H therein, a cylindrical metal core 31A formed of aluminum, iron, or the like, and an elastic layer 31B that covers the cylindrical metal core 31A and is made of silicone rubber having high heat resistance, Furthermore, the elastic layer 31B is covered, and the release layer 31C is made of a fluororesin such as PFA (perfluoroalkyl vinyl ether) or PTFE (polytetrafluoroethylene).

  On the outer peripheral surface of the fixing roller 31, an oil supply unit 41, an external heating unit 42, a cleaning unit 43, a separation claw 44, a temperature sensor (not shown), and the like are arranged.

  The pressure belt 32 is composed of a base formed of polyimide having a thickness of about 100 μm and a release layer formed of PFA or PTFE having a thickness of about 25 μm covering the outer surface of the base. Is formed.

  The pressure belt 32 is wound around the outer periphery of the inlet roller 33 near the introduction portion of the recording material P, the outlet roller 34 near the outlet portion of the recording material P, and the tension roller 35. Abut.

  The separation claw 45 abuts on the outer peripheral surface of the pressure belt 32 around which the exit roller 34 is wound, and separates the leading end portion of the recording material P from the pressure belt 32.

  The elevating means 46 holds the pressure means having the pressure belt 32, the entrance roller 33, the exit roller 34, the tension roller 35, and the like so as to be movable up and down, and presses the pressure belt 32 and the pressing means 36 against the fixing roller 31. .

  The pressing pad 36A that presses the pressure belt 32 from the inside is formed of a silicone rubber having a hardness of about 10 ° JISA, and is formed of a heat-resistant resin, a holding member 36B that holds the pressing pad 36A, and a compression spring that biases the holding member 36B. Along with 36C, it is held in a holder 36D made of heat-resistant resin. Here, the pressing pad 36A, the holding member 36B, the compression spring 36C, and the holder 36D are collectively referred to as pressing means 36.

  In the fixing device 30 configured as described above, the fixing roller 31 heated by the halogen lamp H and driven by driving means (not shown) rotates in the clockwise direction shown in the figure. The pressing pad 36A is pressed by the compression spring 36C via the holding member 36B, and the pressing pad 36A presses the pressure belt 32 against the fixing roller 31.

  Accordingly, the pressure belt 32 is rotated counterclockwise by the fixing roller 31 rotated by driving of the motor M1, which is the first driving source, and is pressed against the fixing roller 31 by the pressing pad 36A to be elastically deformed. A wide fixing nip N is formed between the pressure belt 32 and the fixing roller 31. The unfixed toner on the conveyed recording material P is heated and pressed at the fixing nip N to be fixed.

  The outlet roller 34 rotates by driving the motor M2 that is the second driving source to rotate the pressure belt 32. The entrance roller 33 and the tension roller 35 are driven to rotate by the rotation of the pressure belt 32.

  Even if the sliding resistance of the pressure belt 32 increases during the image forming process, the outlet roller 34 is driven and rotated by a motor M2 different from the motor M1 for driving the fixing roller 31, thereby By providing drive transmission not only from the fixing roller 31 but also from both the fixing roller 31 and the exit roller 34, it is effective for preventing the pressure belt 32 from slipping.

  Here, since the lubricant is applied to the inner surface side of the pressure belt member 32, the grip force between the outlet roller 34 and the pressure belt member 32 is small. If the dynamic resistance is further increased, the gripping force between the fixing roller 31 and the pressure belt 32 cannot be increased even if the outlet roller 34 is simply driven and rotated, so that the surface speed of the pressure belt 32 eventually decreases. There is a problem.

  Further, increasing the grip force between the exit roller 34 and the pressure belt 32 is not easy due to the presence of the lubricant. If the grip force is increased too much, the driving force of the fixing roller 31 and the driving force of the exit roller 34 Is applied to the pressure belt 32, and the pressure belt 32 may be damaged.

  Therefore, when the gripping force between the outlet roller 34 and the pressure belt 32 is small, the driving is transmitted from the outlet roller 34 to the pressure belt 32 by rotating the outlet roller 34 by the motor M2. A great effect is obtained for preventing the belt 32 from slipping.

  However, if the sliding resistance of the pressure belt 32 increases due to wear of the components of the fixing device 30 or exhaustion of the lubricant when printing is performed for a long time, the slip between the outlet roller 34 and the pressure belt 32 becomes large. As a result, slip between the pressure belt 32 and the fixing roller 31 also increases, and a defect that adversely affects the image occurs.

  As a countermeasure against this, the output of the motor M2 is increased in order to restore the reduced rotational surface speed of the pressure belt 32, and the rotational speed of the outlet roller 34 is increased, whereby the drive transmission from the outlet roller 34 to the pressure belt 32 is achieved. The force is increased to prevent the pressure belt 32 from slipping.

  Therefore, in the present invention, in order to measure how long the fixing device has been operated, an integrated time measuring means for measuring the integrated time for heating and fixing the recording material carrying the toner image is provided. The second drive source output control means is provided for increasing the output of the second drive source by a predetermined amount when the cumulative time measuring means measures a predetermined cumulative time.

  Hereinafter, a description will be given with reference to FIG. FIG. 4 is a block diagram of control means for controlling the surface speeds of the pressure belt 32 and the fixing belt 51.

  The accumulated time for heating and pressing and fixing the recording material carrying the toner image can be measured by integrating the time during which the motor M2 is rotating, that is, the time during which the motor M2 is ON. Further, the time during which the motor M1 that is the first drive source for driving the fixing roller 31 is ON may be measured.

  The time during which the motor M2 is turned on is measured by a known accumulated time measuring means 91 to detect that the predetermined accumulated time has been reached, and the output of the motor M2 is output by the second drive source output control means 90. By controlling so as to increase by a predetermined amount, the rotational speed of the outlet roller 34 can be increased, and the reduced surface speed of the pressure belt rotating by the frictional force with the rotating belt can be recovered. For example, when a predetermined time has elapsed, the speed is increased within a range of 10% so that the surface speed of the pressure belt 32 becomes a constant initial speed. Further, when a predetermined time elapses, the speed is further increased within a range of 10%, and the surface speed of the pressure belt 32 is controlled to be a predetermined expected speed.

  FIG. 5 is a diagram showing running characteristics of the fixing roller 31 and the exit roller 34.

  FIG. 5A is a diagram illustrating the relationship of the torque of the fixing roller 31 with respect to the fixing driving time.

  Generally, the torque of the fixing roller 31 tends to increase as the fixing driving time, that is, the number of printed sheets in the image forming process increases.

  FIG. 5B is a diagram illustrating the relationship between the surface speeds of the fixing roller 31 and the exit roller 34 with respect to the fixing driving time.

  The surface speed of the fixing roller 31 driven and rotated by the motor M1 is kept constant regardless of the fixing driving time. The second drive source output control means of the present invention controls to increase the surface speed of the exit roller 34 driven by the motor M2 when a predetermined fixing operation time has elapsed. The amount of change in the surface speed of the exit roller 34 is preferably in the range of 0 to + 10%.

  FIG. 5C is a diagram showing the relationship of the rate of change of the rotational speed of the exit roller 34 with respect to the fixing operation time.

  As the fixing operation time increases, the torque of the fixing roller 31 increases. The second drive source output control means of the present invention controls so as to increase the rotational speed of the exit roller 34 driven by the motor M2. The rate of change in the rotational speed of the exit roller 34 is preferably in the range of 0 to + 10%. The rate of change is 0 to + 10%. The surface friction coefficients of the fixing roller 31, the pressure belt 32, and the pressure pad 36A, the pressure of the pressure pad 36A, the tension of the pressure belt 32 of the tension roller 35, The optimum value is experimentally set according to the peripheral speed of the fixing roller 31 and the pressure belt 32.

  In the above embodiment of the fixing device, the fixing roller 31 is disposed as the heating rotator. However, the present invention is not limited to this, and the fixing roller 31 is rotated by being heated by a heating source instead of the fixing roller 31. The present invention can also be applied to a fixing device having a configuration in which a belt is arranged.

  Further, the fixing belt is rotated by driving the exit roller by the second driving source. However, the present invention is not limited to this, and for example, a pressure belt as described in Patent Document 2 is used. Further, it may be of a type provided with a drive source that drives the pressure belt from the outer surface side of the pressure belt by sandwiching the pressure belt between the belt and a belt support member that circumscribes the pressure belt.

  Further, in the present invention, the pressing means is disposed inside the pressure belt and the pressure belt is pressed against the fixing roller. However, the pressure belt may not be provided.

  FIG. 6 is a side view showing another embodiment of a belt nip type fixing device according to the present invention. Basically, the fixing roller in the fixing device shown in FIG. 3 is replaced with a fixing belt, and the pressure belt is replaced with a pressure roller. The configuration will be briefly described below, but the basic concept is the same as that of the fixing device shown in FIG.

  The fixing device of this embodiment includes a fixing belt 51 above the sheet passing path and a pressure roller 52 below the sheet passing path.

  A single color toner image or a multicolor toner image on the recording material P is fixed by heating and pressing through a fixing nip formed between the fixing belt 51 and the pressure roller 52.

  The fixing belt 51 is an endless belt composed of a base made of polyimide having a thickness of about 100 μm and a release layer made of PFA or PTFE having a thickness of about 25 μm covering the outer surface of the base.

  The fixing belt 51 is wound around the outer periphery of an entrance roller 53 near the introduction portion of the recording material P, an exit roller 54 near the exit portion of the recording material P, and a heating roller 55 containing a halogen lamp H1 therein. , Abuts against the outer peripheral surface of the pressure roller 52 containing the halogen lamp H2 therein.

  A pressing pad 56 that presses the fixing belt 51 from the inside is formed of silicone rubber having a hardness of about 10 ° JISA, is formed of a heat resistant resin, and is biased by a spring.

  A pressing means (not shown) holds the pressure roller 52 so as to be movable up and down, and presses the pressure roller 52 against the fixing belt 51.

  In the fixing device 50 configured as described above, the fixing roller 31 driven by a driving unit (not shown) rotates in the clockwise direction shown in the drawing, contacts the heating roller 55 heated by the halogen lamp H1, and is heated by heat conduction. Is done. The pressing pad 56 presses the fixing belt 51 against the pressure roller 52.

  The pressure roller 52 rotates counterclockwise as shown in the figure by driving of a motor M5 that is a first drive source. The fixing roller 55 rotates clockwise as shown in the figure by driving the motor M3.

  Since the fixing belt 51 is elastically deformed by pressing the pressure roller 52 by the exit roller 54 and the pressing pad 56, a wide fixing nip portion is formed between the fixing belt 51 and the pressure roller 52. The unfixed toner on the conveyed recording material P is heated and pressed at the fixing nip N to be fixed.

  The exit roller 54 rotates by driving the motor M4 that is the second drive source to rotate the fixing belt 51. The entrance roller 53 is driven and rotated by the rotation of the exit roller 54.

  The pressure roller 52 rotates counterclockwise as shown in the figure by driving of a motor M5 that is a first drive source. The surface speed of the fixing belt 51 is controlled to be constant by the second drive source output control means 90.

  In another embodiment of the belt nip type fixing device 50 shown in FIG. 6, the surface speed of the fixing belt 51 is controlled (see the block diagram of FIG. 4).

  In the fixing device 50 having the pressure roller 52 that rotates in pressure contact with the fixing belt 51, the rotational speed of the outlet roller 54 connected to the motor M4 among the plurality of rollers that rotatably stretch the fixing belt 51 is set as follows: The surface speed of the fixing belt 51 is variably controlled so as to be constant.

  That is, the rotation integration time of the exit roller 54 driven and rotated by the motor M4 is counted by a known rotation accumulator or the like, and the rotation of the exit roller 54 is detected by controlling that the predetermined rotation integration time has been reached. The speed is increased within a range of 10%, and the surface speed of the fixing belt 51 is controlled to be a constant initial speed.

  As described above, in the description of the image forming apparatus main body A, the color image formation has been described. However, the present invention includes a case of forming a monochrome image.

Configuration of an image forming apparatus according to the present invention 1 is a cross-sectional view of a belt nip type fixing device according to the present invention. The expanded sectional view of a fixing roller and a pressure belt member. The block diagram of the control means which controls the surface speed of a pressure belt and a fixing belt. The figure which shows the running characteristic of a fixing roller and an exit roller. FIG. 6 is a side view showing another embodiment of a belt nip type fixing device according to the present invention.

Explanation of symbols

30 fixing device 31 fixing roller 32 pressure belt 33 inlet roller 34 outlet roller 35 tension roller 36 pressing means 36A pressing pad 50 fixing device 51 fixing belt 52 pressure roller 53 inlet roller 54 outlet roller 55 heating roller 56 pressing pad 90 second Drive source output control means 91 Accumulated time measurement means H, H1, H2 Halogen lamp M1, M2, M3, M4, M5 Motor N Fixing nip P Recording material

Claims (9)

Fixing having a fixing nip portion that holds a recording material carrying a toner image between a fixing roller that is driven and rotated by a first driving source and an endless pressure belt that rotates while being pressed against the fixing roller, and that is heated and pressurized and fixed. In the device
A second drive source for rotating the endless pressure belt;
An accumulated time measuring means for measuring an accumulated time for heating and pressing and fixing the recording material carrying the toner image;
Second drive source output control means for increasing the output of the second drive source according to the accumulated time measured by the accumulated time measuring means;
A fixing device comprising: The endless pressure belt is
An inlet roller disposed on the inlet side for feeding the recording material carrying the toner image to the fixing nip portion, and an outlet roller for pressing the endless pressure belt against the fixing roller at the most downstream portion of the fixing nip portion And stretched by at least three rollers of a tension roller that applies tension to the endless pressure belt,
The fixing device according to claim 1, wherein the fixing roller is pressed against the fixing roller by a pressing unit disposed inside the endless pressure belt at the fixing nip portion. The fixing device according to claim 2, wherein the second driving source rotates the endless pressure belt by driving the outlet roller. 2. The fixing device according to claim 1, wherein the second drive source output control unit increases the output of the second drive source by a predetermined amount when the integration time measurement unit measures a predetermined integration time. . A fixing nip portion that sandwiches a recording material carrying a toner image by a pressure roller that is driven and rotated by a first driving source and an endless fixing belt that rotates while being pressed against the pressure roller, and that is heated and pressurized and fixed; In the fixing device,
A second drive source for rotating the endless fixing belt;
An accumulated time measuring means for measuring an accumulated time for heating and pressing and fixing the recording material carrying the toner image;
Second drive source output control means for increasing the output of the second drive source according to the accumulated time measured by the accumulated time measuring means;
A fixing device comprising: The endless fixing belt is
An inlet roller disposed on the inlet side for feeding the recording material carrying the toner image to the fixing nip portion, and an outlet roller for pressing the endless fixing belt against the pressure roller at the most downstream portion of the fixing nip portion And stretched by at least three rollers, tension rollers for applying tension to the endless fixing belt,
The fixing device according to claim 5, wherein the fixing roller is pressed against the pressure roller by a pressing unit disposed inside the endless fixing belt. The fixing device according to claim 6, wherein the second driving source rotates the endless fixing belt by driving the exit roller. 6. The fixing device according to claim 5, wherein the second drive source output control unit increases the output of the second drive source by a predetermined amount when the integrated time measuring unit measures a predetermined integrated time. . Image forming means for forming a toner image on an image carrier, paper feeding means for supplying a recording material to the image forming means, transfer means for transferring the toner image to the recording material, and the transferred toner image An image forming apparatus comprising: the fixing device according to claim 1, wherein the fixing device is fixed to the recording material.

Images