JP2010217232A - Fixing device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device capable of reducing difference in relative speed between a fixation belt unit and a nip part of a pressurizing roller and capable of preventing formation of abnormal image being likely to occur in an intermediate region of the nip part, and to provide an image forming device using this fixing device. <P>SOLUTION: The fixing device includes a fixing roller 12, a separation roller 13 having smaller diameter than that of the fixing roller 12, a fixing belt 11 stretched over the fixing roller 12 and the separation roller 13, the pressurizing roller 14 coming into pressure-contact with the fixing roller 12 and the separation roller 13 through the fixing belt 11 to form the nip part, a first driving mechanism 11s composed of a first motor 11m and a drive transmission system 11t having a one-way clutch to transmit drive of the first motor 11m to the fixing roller 12 through the one-way clutch and transmit drive of the first motor 11m to the separation roller 13, and a second driving mechanism 14s composed of a second motor 14m and a drive transmission system 14t to transmit drive of the second motor 14m to the pressurizing roller 14. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fixing belt driving type fixing device and an image forming apparatus which is an OA device such as a laser beam printer, a digital copying machine, and a plain paper fax machine using the fixing device.

  In an image forming apparatus using toner for forming a visible image, a fixing device is provided to fix the toner image as a permanent image on a recording medium such as transfer paper. The fixing device records a pressure contact portion formed by a heated and rotating fixing member (fixing roller or fixing belt) and a pressure member (pressure roller or pressure belt) that presses and rotates with the fixing member. As the medium passes, the toner carried on the recording medium is melted and the toner image is fixed on the recording medium.

  In recent years, energy saving has progressed, and a smaller heat capacity type fixing device than a heat storage type using a fixing member having a high heat capacity that requires a large amount of electric power has become mainstream. For this reason, there are an increasing number of fixing devices using an endless fixing belt having a small heat capacity in the heat accumulating section, using a fixing roller using heat insulation type foamed silicon or the like rather than a fixing roller having a large heat capacity. When the fixing belt is used, since the heat capacity is small, the temperature of the fixing belt can be raised to the required temperature in a short time when the fixing device is started up, and the warm-up time can be shortened. Therefore, it is an indispensable member in a fixing device for the purpose of energy saving. As the base of the fixing belt, an endless polyimide resin having high heat resistance, a small amount of thermal expansion, and relatively high strength is frequently used. In many cases, the surface layer is coated with silicon rubber or the like as an elastic layer, and the outermost layer is coated or coated with a fluorine-based tube having excellent releasability from the toner.

  In recent years, higher speed and higher productivity have been demanded, and the machine size cannot be increased. Therefore, in belt fixing, studies have been made to make the pressure contact portion for sandwiching and heating and pressing the recording medium as wide as possible. As an achievement means, not only the nip portion (pressure contact portion) between the fixing roller and the pressure roller sandwiching the fixing belt (or pressure belt) but also the fixing belt (or pressure belt) using another roller or another member. Fixing for high speed and high productivity by improving the fixability by widening the nip part (pressure contact part) (also referred to as increasing the nip width) by the structure wound around the pressure roller (or fixing roller). The number of devices is increasing. In addition, there is an increasing demand for paper type diversity, and it is also necessary to change the length of the nip portion by changing the pressure roller position according to the paper type.

  However, in this type of fixing device, in addition to the first nip portion between the fixing roller and the pressure roller having a stable pressure, there is a second nip portion by another roller and another member. The pressure of the part tends to become unstable, and there are problems such as disturbing the image at the intermediate nip part of the unstable pressure. This is because the fixing belt (or pressure belt) is liable to float or slip and a relative speed difference between the fixing side and the pressure side occurs at an unstable intermediate nip.

  As an invention for solving the above-described problem, Patent Document 1 discloses that a pressure belt is provided so that a fixing belt is stretched over a heating roller, a driving roller, and a support / pressing roller, and is pressed against the driving roller and the supporting / pressing roller with the fixing belt interposed therebetween. The structure which provides is proposed. In this invention, the drive roller is disposed downstream of the support / press roller (in the direction of recording paper passage), the shafts of the drive roller and the pressure roller are pivotally attached to the arm member, and the gears at the shaft end portions mesh with each other. Is done. A pulling force in the recording paper discharge direction is applied to the drive roller. This prevents the fixing belt from floating and slipping. Further, the nip pressure between the driving roller and the pressure roller is always stable, and a satin image can be prevented.

  With the above configuration, floating at the intermediate nip located between the first nip between the support / press roller and the pressure roller and the second nip between the drive roller and the pressure roller and reduction of unstable pressure are improved. However, since the driving roller and the pressure roller are gear-connected to each other, the speeds of each other cannot be adjusted separately.

  Patent Document 2 also discloses an invention relating to a reduction in the relative speed difference between the fixing member and the pressure member. According to the present invention, a fixing roller that is driven and rotated by a first driving source and a recording material that carries a toner image is sandwiched between an endless pressure belt that rotates while being pressed against the fixing roller, and fixing is performed by heating and pressing. In a fixing device having a nip portion, a second drive source for rotating an endless pressure belt, an integrated time measuring means for measuring an integrated time for heating and pressurizing a recording material carrying a toner image in the fixing nip portion, and And a second drive source output control unit that increases the output of the second drive source by a predetermined amount when the accumulated time measuring unit measures a predetermined accumulated time.

  The above-described configuration is a configuration that reduces the relative speed fluctuation between the fixing roller and the pressure belt unit that occurs in the initial stage and over time for the purpose of improving durability. This is effective for reducing the relative speed fluctuation that occurs in the span with a long unit life, but there are problems that cannot cope with the difference in the set temperature for each paper type and the relative speed fluctuation that occurs between the initial stage and the passage of time.

  The present invention has been made in view of the above problems in the prior art, and reduces the relative speed difference between the nip portion of the fixing belt unit (fixing belt, fixing roller, separation roller) and the pressure roller, thereby reducing the nip portion. It is an object of the present invention to provide a fixing device and an image forming apparatus using the fixing device that prevent an abnormal image that tends to occur in the intermediate region. It is another object of the present invention to provide an image forming apparatus in which a gloss imparting device is provided downstream of the fixing device and gloss control is performed, and accordingly, problems such as image distortion and recording medium wrinkles do not occur.

The present invention provided to solve the above problems is as follows.
[1] A fixing roller (fixing roller 12) as a driving roller, a separation roller (separation roller 13) as a driving roller, and an endless fixing belt (fixing belt 11) spanned between the fixing roller and the separation roller A pressure roller (pressure roller 14) that forms a nip portion (nip portion N1) by being pressed against the fixing roller and the separation roller via the fixing belt, and a first motor (first motor). 11m) and a one-way clutch (one-way clutch 18a), and a drive transmission system (drive transmission system 11t) in which the circumferential speed (Vs) of the separation roller is larger than the circumferential speed (Vf) of the fixing roller. A first drive mechanism (first drive mechanism 11s) that transmits the drive of the first motor to the fixing roller via the one-way clutch and transmits the drive of the first motor to the separation roller. ), A second motor (second motor 14m), and a drive transmission system (drive transmission system 14t), and a second drive mechanism (second drive mechanism) that transmits the drive of the second motor to the pressure roller. 14s), and when the peripheral speed (Vp) of the pressure roller is greater than the peripheral speed (Vf) of the fixing roller, the one-way clutch is idled and the fixing roller is The fixing device (fixing device 5, FIGS. 1 to 5) characterized by being rotated with the rotation of the motor.
[2] When the peripheral speed (Vp) of the pressure roller is greater than the peripheral speed (Vf) of the fixing roller, the one-way clutch is idled and the fixing roller is rotated as the pressure roller rotates. The fixing device according to [1] (FIG. 5), wherein the fixing roller rotates and is driven and rotated by a first driving mechanism.
[3] The first drive mechanism rotates in the drive transmission system when the peripheral speed (Vp) of the pressure roller is larger than the peripheral speed (Vs) of the separation roller. The fixing device according to the above [2] (FIG. 4D), which has a second one-way clutch (one-way clutch 22 a) that rotates along with the rotation of the pressure roller.
[4] When the peripheral speed of the pressure roller is Vp, and the peripheral speeds of the fixing roller and the separation roller when the one-way clutch is locked are Vf and Vs, Vs ≧ Vp> The fixing device according to any one of [1] to [3], wherein drive control of the first drive mechanism and / or the second drive mechanism is performed so that a relationship of Vf is established.
[5] First motor detection means for detecting any of the current value, power value, and torque command value of the first motor; and first motor rotation speed change means for changing the rotation speed of the first motor. And performing feedback control on the rotational speed of the first motor so that the detection value of the first motor detection means is within a predetermined range during conveyance of the recording medium, and the relationship of Vs ≧ Vp> Vf is established. The fixing device as described in [4] above.
[6] An image forming apparatus (image forming apparatus 100, FIG. 6) comprising the fixing device (fixing device 5) according to any one of [1] to [5].
[7] A heating member (heating roller 80), a pressure member (pressure roller 90) that presses against the heating member to form a nip portion (nip portion N2), and rotates the heating member or pressure member. A gloss imparting device (gloss imparting device 6) having a third drive mechanism (third drive mechanism 80s) including a third motor (third motor 80m) to be provided on the downstream side of the fixing device in the recording medium conveyance direction, When the conveyance speed of the recording medium in the fixing device is V1, and the conveyance speed in the gloss applying device is V2, the drive control in the third drive mechanism is performed so that the relationship of 1.05 × V1 ≧ V2 ≧ V1 is established. The image forming apparatus according to [6], wherein the image forming apparatus is performed (FIGS. 7 to 9).
[8] Third motor detection means for detecting any of the current value, power value, and torque command value of the third motor; and third motor rotation speed changing means for changing the rotation speed of the third motor. And the feedback control is performed on the rotation speed of the third motor so that the detection value of the third motor detection means is within a predetermined range during conveyance of the recording medium, and a relationship of 1.05 × V1 ≧ V2 ≧ V1 The image forming apparatus as set forth in [7], wherein

According to the fixing device of the present invention, the fixing belt unit (the fixing belt, the fixing roller, and the separation roller) and the pressure roller are driven and transmitted from separate motors (drive sources), so that the peripheral speed between them is adjusted. Is possible by adjusting the drive source. Further, by inserting a one-way clutch in the drive transmission system in the first drive mechanism, the fixing roller and the separation roller are rotated with respect to the pressure roller even if the peripheral speed of the pressure roller is set high. As a result, the relative speed difference between the nip portion of the fixing belt unit (fixing belt, fixing roller, separation roller) and the pressure roller can be reduced, and fixed image defects such as rubbing and distortion can be prevented. The pressure roller is adjusted by adjusting the rotation speed of the first motor so that the speed of the fixing belt unit is equal to the speed of the pressure roller as much as possible under the condition that the speed of the fixing belt unit is smaller than the speed of the pressure roller. The load on the side can be reduced, and the conditions can be set so that the relative speed difference does not easily occur.
Further, according to the image forming apparatus of the present invention, since the fixing device of the present invention is used, abnormal images that tend to occur in the nip of the intermediate region of the nip portion in the fixing device are different in mode depending on the type of paper or during paper passing. Stable image formation that does not occur due to a difference in state can be performed. Further, even when the gloss control device is provided downstream of the fixing device to control the gloss of the image, the predetermined drive control can prevent problems such as image distortion and paper wrinkles.

2 is a cross-sectional view illustrating a configuration example of a fixing device according to the present invention. FIG. FIG. 2 is a cross-sectional view illustrating a configuration of a pressure unit of the fixing device in FIG. 1. FIG. 2 is a perspective view illustrating a configuration of two drive mechanisms included in the fixing device of FIG. 1. FIG. 4 is a diagram illustrating a drive transmission path of two drive transmission systems in the fixing device. FIG. 2 is a diagram illustrating a relationship between a rotation speed of a first motor and a current value (or power value, torque command value) of the first motor in the fixing device of FIG. 1. 1 is a cross-sectional view illustrating a configuration example of an image forming apparatus according to the present invention. It is the schematic which shows the principal part structure of the image forming apparatus of FIG. FIG. 4 is a perspective view illustrating a configuration of a driving mechanism in a fixing device and a gloss applying device. It is a figure which shows the relationship between the rotation speed of a 3rd motor and the electric current value (or electric power value, torque command value) of a 3rd motor in the combination of a fixing device and a glossiness imparting device. FIG. 6 is a cross-sectional view illustrating another configuration example of the fixing device according to the present invention.

The fixing device and the image forming apparatus according to the present invention will be described below.
FIG. 1 is a cross-sectional view illustrating a configuration of a fixing device according to the present invention, and is a view of the fixing device as viewed from the operation side.
The fixing device 5 includes a cylindrical fixing roller 12, a separation roller 13, a heating roller 15, a tension roller 16, a driven roller 17, the fixing roller 12, the separation roller 13, the heating roller 15, the tension roller 16, and The fixing belt 11 is stretched around the driven roller 17 with a constant tension, and the pressure roller 14 is in pressure contact with the fixing belt 11 so as to be rotatable and forms a nip portion N1. Here, the pressure roller 14 has a double nip configuration where the fixing roller 12 and the separation roller 13 are pressed against each other via the fixing belt 11. A configuration in which the fixing belt 11, the fixing roller 12, the separation roller 13, the heating roller 15, the tension roller 16, and the driven roller 17 are combined is referred to as a fixing belt unit. In addition, a separation member 43 that is disposed on the paper discharge side of the nip portion N <b> 1 and has a leading end disposed in the vicinity of the pressure roller 14 to prevent the paper from being wound around the pressure roller 14 is provided.

  Here, the fixing belt 11 is an endless belt that fixes an unfixed toner T on a recording medium (also referred to as paper) P, and has a cross-sectional structure such as a silicon rubber layer or the like on a base material such as nickel, stainless steel, or polyimide. It has a laminated structure in which an elastic layer is formed. For example, the fixing belt 11 has an inner diameter of 115 mm, high heat resistance, a small amount of thermal expansion, and a relatively large strength endless polyimide resin. And a fluorine-based tube (PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), etc.) excellent in releasability.

  The fixing roller 12 is a roller formed by forming a heat resistant elastic layer such as foamed silicon rubber on the outer periphery of a hollow cylindrical base roller. For example, a heat resistant elastic layer made of foamed silicon rubber having a thickness of 14 mm is formed on the outer periphery of the base roller. The outer diameter is 65 mm.

  The separation roller 13 has a smaller outer diameter than that of the fixing roller 12 and is made of a metal core with a built-in heat pipe coated with fluororesin or solid rubber for the purpose of preventing temperature unevenness in the axial direction. . For example, a roller having an outer diameter of 16 mm obtained by coating a 1 mm thick aluminum roller with a fluororesin. The separation roller 13 is configured to be rotatable about the axis of the fixing roller 12 and is configured to be pressed by the pressure roller 14 via the fixing belt 11.

  The tension roller 16 has a function of applying a predetermined tension to the fixing belt 11 by a mechanism using a spring spring. In the fixing device 5, for example, a tension of 9.8N on one side and a total of 19.6N on both sides is applied.

  The heating roller 15 is an aluminum or iron hollow roller, for example, an aluminum hollow cylindrical roller having an outer diameter of 35 mm and a thickness of 0.6 mm. Further, it has a heat source composed of a heater 15h such as a halogen heater for heating the fixing belt 11 and is not in pressure contact with the pressure roller 14 on the inner peripheral side of the fixing belt 11, that is, the nip portion N1. Are arranged so as not to have a heating source. The heat source may be an induction heating mechanism (IH). Further, a temperature detection sensor 62 that detects the temperature of the region where the fixing belt 11 is in contact with the heating roller 15 is provided.

The pressure roller 14 is usually a cylindrical roller in which an elastic layer such as silicon rubber is provided on a core metal such as aluminum or iron. For example, the outer periphery of a steel hollow core metal having a thickness of 1 mm is formed with a thickness 1 A roller having an outer diameter of 65 mm, covered with 5 mm silicon rubber, and further coated with a PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) tube on the outermost layer. The pressure roller 14 has a heater 14h inside, and the lighting of the heater 14h is controlled based on the temperature of the pressure roller 14 detected by the temperature detection sensor 72, and the sheet passes through the nip portion N1. This prevents the pressure roller 14 from taking heat away from the paper.
A web cleaning unit 14c that removes offset toner, paper dust, and the like on the roller is provided on the outer periphery of the pressure roller 14.

  As shown in FIG. 2, the pressure roller 14 is provided with a pressure means including a pressure lever 76, a spring 77, a pressure member 76 a, and a cam 78. The pressure roller 14 presses the fixing roller 12 and the separation roller 13 in pressure contact with each other via the fixing belt 11 by the pressure unit, and the position thereof depends on the type of recording medium (paper type) and mode (gloss). And a mode in which the gloss is not given). FIG. 2 shows two states, a state in which the nip pressure is maximized and a state in which the nip pressure is minimized as the cam 78 rotates in the pressurizing means.

  As an operation for bringing the pressure roller 14 into a pressure state by the pressure means, first, when the cam 78 is rotated by a constant rotation angle in the direction of the arrow in the drawing by an external driving force, the cam 78 is added. The pressure member 76a is pushed up (in the direction of the arrow in the figure). When the pressure member 76a is pushed, the spring 77 fixed to the pressure member 76a pushes up the end of the pressure lever 76 with a constant pressure. Next, when the end of the pressure lever 76 on the spring 77 side is pushed up, the pressure lever 76 rotates about the support shaft 76b (counterclockwise direction in FIG. 2). Next, the end of the pressure lever 76 on the spring 77 side and the pressure portion 76c in the middle of the support shaft 76b abuts against the shaft of the pressure roller 14 and acts to push in the direction of the fixing roller 12. Finally, the pressure roller 14 is pressed against the fixing roller 12 and the separation roller 13 via the fixing belt 11, and the first nip portion formed by the fixing roller 12 and the pressure roller 14, and the first roller formed by the separation roller 13 and the pressure roller 14. The two nip portions are formed in a state where they are pressurized at a constant pressure, and the nip portion N1 for fixing is also included including the intermediate nip portion between them. Note that the spring 77 can be omitted as the pressurizing means. In this case, the cam 78 directly acts to push up the end of the pressure lever 76.

  At this time, the pressure roller 14 bites into the fixing roller 12 through the fixing belt 11 with a predetermined depth (for example, 3 to 3.5 mm). Further, the separation roller 13 is pressed against the pressure roller 14 with a predetermined pressure (for example, a force of 9.8 N on one side). Accordingly, the nip portion N1 has a predetermined nip width (for example, 35 mm). With this wide nip portion, it becomes possible to improve the fixability of a wide variety of paper types, and to achieve high speed and high productivity.

  When the fixing device 5 is driven, for example, in FIG. 1, the fixing belt 11 and the separation roller 13 are rotated in the clockwise direction in the drawing, and the fixing belt 11 is appropriately tensioned by the driven roller 17 and the tension roller 16. In the applied state, the paper P is rotated in the direction of discharging the paper P (clockwise in FIG. 1). The pressure roller 14 is also driven to rotate counterclockwise in the drawing. These drive mechanisms will be described later. Further, at the time of fixing, the fixing belt 11 is heated to a predetermined temperature (for example, a temperature suitable for toner fixing) by the temperature detection sensor 62 due to the heat generated by the heater 15 h disposed inside the heating roller 15. The

  Next, the paper P on which the unfixed toner T is formed is passed through the nip portion N1 (paper passing from the right side to the left side in the drawing), and the unfixed toner T is applied to the paper P by pressurization and heating at the nip portion N1. Fixing is performed by heat fusing.

At this time, in the nip portion N1, the toner T on the paper P is almost fixed in the entrance region. Then, the toner is sufficiently melted and has a strong viscosity, so that the paper P sticks to the fixing belt 11 and proceeds through the intermediate region. The nip pressure of 5 N / cm ² or more is required. Further, the nip pressure is 15 N / cm ² or less so as not to rise to a glossy state. The paper P is separated from the fixing belt 11 by the separation force with a strong curvature separation of the separation roller 13 which is a small diameter roller, and is separated from the pressure roller 14 by the separation member 43 and discharged.

The nip portion N1 has a total nip time of 60 msec or more with respect to the linear velocity, and the nip pressure is 15 to 30 N / cm ² in a region of 50% or more of the entire nip width (mode for imparting gloss). Time). As a result, sufficient fixing can be performed by the fixing device 5 including thick paper (paper weighing about 300 g / m ² ).

Further, by changing the contact state between the fixing roller 12 and the pressure roller 14 in the fixing belt 11, the nip width of the intermediate region can be adjusted. Therefore, when using a sheet of paper having a weight less than that of plain paper, the contact state between the fixing roller 12 and the pressure roller 14 is adjusted to increase the nip width in the intermediate region of 5 to 15 N / cm ² . In this way, when the amount of heat supplied increases such as using thin paper such as plain paper, the nip pressure can be lowered to suppress gloss. As a result, in the non-glossy mode in the image forming apparatus to be described later, even when using a sheet of paper that is less than or equal to plain paper that tends to have a large amount of heat, an image equivalent to that of thick paper can be obtained by adjusting the nip width. Gloss can be maintained. Also, in the glossing mode, the final image glossiness is made constant by adjusting the nip width of the intermediate region in consideration of the sheet thickness and adjusting the nip pressure in the fixing device 5. Is possible. Therefore, it is possible to improve the reliability of the desired gloss in each of the mode that imparts gloss and the mode that does not impart gloss.

As an example of the pressing condition, the distribution of the nip pressure in the nip portion N1 is set to a load of 15 at the entrance region in the sheet conveyance direction (the contact portion between the pressing roller 14 and the fixing roller 12 (first nip portion)). -30 N / cm ^2, and the load of the exit region (the contact portion (second nip portion) between the pressure roller 14 and the separation roller 13) is 15-30 N / cm ² . Moreover, it is 5-15 N / cm < ² > in the intermediate | middle area | region which is between the said entrance area | region and an exit area | region. When the recording medium is glossy paper by the pressurizing means (mode to give gloss), the nip width of the first nip portion (between the fixing roller 12 and the pressure roller 14) in the nip portion N1 is 20 mm, and the intermediate region The nip width of the second nip portion (between the separation roller 13 and the pressure roller 14) is 2 mm. When the recording medium is plain paper (mode not giving gloss), the nip width of the first nip portion (between the fixing roller 12 and the pressure roller 14) in the nip portion N1 is 15 mm, the nip width of the intermediate region is 13 mm, The nip width of the second nip portion (between the separation roller 13 and the pressure roller 14) is 1 mm.

Next, the basic part of the present invention will be described.
FIG. 3 shows the fixing device 5 in which the fixing belt unit (a combination of the fixing belt 11, the fixing roller 12, the separation roller 13, the heating roller 15, the tension roller 16 and the driven roller 17) and the pressure roller 14 are independently driven. It is a perspective view which shows having provided the drive mechanism.

  Here, the fixing device 5 includes a first motor 11m, a one-way clutch, a joint gear 11g, and a drive transmission system 11t having a plurality of drive transmission gears corresponding to the fixing belt unit, and the first motor 11m. Corresponding to the pressure roller 14 and the first drive mechanism 11 s that transmits the drive of the first motor 11 m to the separation roller 13 and the pressure roller 14. A motor 14m, a joint gear 14g, and a drive transmission system 14t having a plurality of drive transmission gears, and a second drive mechanism 14s that transmits the drive of the second motor 14m to the pressure roller 14.

  The first motor 11m and the second motor 14m are provided on the image forming apparatus main body, which will be described later. When the fixing device 5 is mounted on the image forming apparatus main body, the first motor 11m and the fixing belt unit are driven. The joint gear 11g which is an input part is connected. Similarly, the second motor 14m is connected to a joint gear 14g that is a drive input portion of the pressure roller 14.

  With the above configuration, the drive of the first motor 11m is transmitted to the fixing belt unit by the drive transmission system 11t through the joint gear 11g, and the drive of the second motor 14m is applied by the drive transmission system 14t through the joint gear 14g. It is transmitted to the pressure roller 14. Further, the driving of the fixing belt unit and the pressure roller 14 can be independently controlled by the first driving mechanism 11s and the second driving mechanism 14s.

  FIG. 4 is a diagram illustrating a drive transmission path of the drive transmission systems 11t and 14t in the fixing device 5. 4, (a) is a front view of the fixing device 5 as viewed from the drive side, (b) is a view as seen from A in (a), (c) is a sectional view of the fixing gear 18, and (d) is a shaft. 2 is a cross-sectional view of a drive gear 20 and a one-way gear 22. FIG. The first motor 11m and the second motor 14m are omitted.

  The drive transmission system 11t includes a joint gear 11g connected to the first motor 11m, a fixing gear 18 meshed with the joint gear 11g, a two-stage gear 19 which is two gears meshed with the fixing gear 18, and 2 A shaft drive gear 20 that meshes with one gear of the step gear 19, a drive transmission shaft 21 that is a rotatable shaft to which the shaft drive gear 20 and the one-way gear 22 are fixed, and a separation that meshes with the one-way gear 22. And a roller gear 23.

  The drive transmission system 14t includes a joint gear 14g connected to the second motor 14m, a pressure idler gear 24 meshed with the joint gear 14g, and a pressure gear 25 meshed with the pressure idler gear 24. Is done.

  Here, the drive transmission in the first drive mechanism 11s is performed as follows. First, the drive is transmitted from the first motor 11m to the joint gear 11g connected thereto. Next, the drive is transmitted directly to the fixing gear 18 from the joint gear 11g. At this time, as shown in FIG. 4C, the fixing gear 18 has a structure in which a one-way clutch 18a is built in the fixing gear 18, and the flange of the fixing roller 12 is interposed via the one-way clutch 18a. The drive is transmitted to the portion 12a, and the fixing roller 12 is rotatable by receiving this drive.

  In addition, driving is transmitted from the fixing gear 18 to the two-stage gear 19, and the rotation speed is amplified by the action of the two-stage gear 19. Then, the drive transmission is transmitted from the two-stage gear 19 to the shaft drive gear 20, and the drive of the shaft drive gear 20 is transmitted to the drive transmission shaft 21. Further, the drive of the drive transmission shaft 21 is transmitted to the one-way gear 22 via a one-way clutch 22a, which is a second one-way clutch, as shown in FIG. 4 (d). Finally, the driving of the one-way gear 22 is transmitted to the separation roller gear 23 so that the separation roller 13 can rotate.

  The one-way clutches 18a and 22a are directional couplings. When the rotation of the gear on the drive shaft side is faster than the rotation of the gear on the driven shaft side, the drive is transmitted with both clutched. However, when the rotation is slower than the rotation of the gear on the driven shaft side, the clutch between the two is disengaged to idle, and the drive is not transmitted. That is, when the rotation of the fixing gear 18 (drive shaft side gear) is faster than the rotation of the flange portion 12a (driven shaft side gear), the one-way clutch 18a is in a state where both are clutched. When the drive of 11m is transmitted and it is slower than the rotation of the flange portion 12a (the driven shaft side gear), the clutch between both is disengaged and idles, and the drive of the first motor 11m is not transmitted. Yes. Further, when the rotation of the shaft driving gear 20 (drive shaft side gear) is faster than the rotation of the one-way gear 22 (driven shaft side gear), the one-way clutch 22a is in a state where both are clutched. When the drive of the motor 11m is transmitted and the one-way gear 22 (driven shaft side gear) is slower than the rotation, the clutch between the two is disengaged to idle, and the drive of the first motor 11m is not transmitted. ing.

  At this time, in the gear drive by the action of the two-stage gear 19, when the circumferential speed of the fixing roller 12 is Vf and the circumferential speed of the separation roller 13 is Vs in a state where the one-way clutches 18a and 22a are clutched (locked), Vs The gear ratio is set so that the relationship> Vf is established.

  Accordingly, when the peripheral speed of the pressure roller 14 is greater than the peripheral speed of the fixing roller 12, the one-way clutch 18 a rotates idly and the fixing roller 12 rotates with the rotation of the pressure roller 14.

  When the peripheral speed of the pressure roller 14 is greater than the peripheral speed of the separation roller 13, the one-way clutch 22 a is idled and the separation roller 13 rotates with the rotation of the pressure roller 14.

  On the other hand, in the second drive mechanism 14s, first, the drive is transmitted from the second motor 14m to the joint gear 14g connected thereto. Next, the drive is transmitted from the joint gear 14 g to the pressure idler gear 24, and the drive is further transmitted from the pressure idler gear 24 to the pressure gear 25. At this time, the one-way clutch is not built in the pressure idler gear 24 and the pressure gear 25, and the drive is transmitted as it is to the flange portion of the pressure roller 14, and the pressure roller 14 receives this drive and rotates. It is like that.

  With the above configuration, the fixing belt unit and the pressure roller 14 are independently driven and controlled by the first driving mechanism 11s and the second driving mechanism 14s, respectively. However, the fixing roller 12 and the separation roller 13 have the one-way clutches 18a and 22a. Therefore, even if the peripheral speed of the pressure roller 14 is set to be larger than the peripheral speeds of the fixing roller 12 and the separation roller 13, the fixing roller 12 and the separation roller 13 are the pressure roller. 14, the peripheral speeds of the fixing roller 12 and the separation roller 13 do not become slower than the peripheral speed of the pressure roller 14. That is, the relative speed difference at the nip portion N1 between the fixing belt unit and the pressure roller 14 is reduced, and abnormal images that tend to occur at the intermediate nip portion can be prevented.

Next, when the peripheral speed of the pressure roller 14 is Vp, drive control of the first drive mechanism 11s and / or the second drive mechanism 14s is performed so that the following relational expression (1) is satisfied during conveyance of the recording medium. Is preferably performed.
Vs ≧ Vp> Vf (1)

  In FIG. 5, in the fixing device 5, the first fixing belt unit that drives the fixing belt unit that is set to satisfy Vs> Vf according to the gear ratio of the two-stage gear 19 under a constant rotation speed of the pressure roller 14. The relationship between the rotation speed of the motor 11m and the current value (or power value, torque command value) of the first motor 11m is shown. In the drawing, the relationship between the peripheral speeds Vf and Vs of the fixing roller 12 and the separation roller 13 and the peripheral speed Vp of the pressure roller 14 which are assumed to be the clutches (locked) of the one-way clutches 18a and 22a is shown. Yes.

  The relationship between the rotation speed of the first motor 11m and the current value (or electric power value, torque command value) is basically proportional to the current value increasing as the rotation speed increases. Can be divided into three regions having different slopes (increase rates).

  That is, when the rotational speed of the first motor 11m is small, the relationship between the peripheral speeds of the respective rollers is Vp> Vs> Vf, and the fixing roller 12 and the separation roller 13 are operated by the one-way clutches 18a and 22a. Therefore, the torque, that is, the current and power of the first motor 11m is small, and the torque command value is also small (region (1)). In addition, as long as the fixing roller 12 and the separation roller 13 are rotated, the current value, power value, and torque command value increase only slightly even if the rotation speed of the first motor 11m increases. The torque command value is a torque value to be output by the first motor 11m that is instructed from the drive system control unit of the fixing device 5 to the controller of the first motor 11m.

  Next, when the rotational speed of the first motor 11m is increased, Vs> Vf is set, so that the circumferential speed Vs of the separation roller 13 first exceeds the circumferential speed Vp of the pressure roller 14, The relationship between the peripheral speeds of the rollers is Vs> Vp> Vf (region (2)). As a result, in the first drive mechanism 11s, the one-way clutch 18a is idled, the fixing roller 12 is rotated along with the rotation of the pressure roller 14, and the one-way clutch 22a is clutched to drive the first motor 11m. , The torque of the first motor 11m, that is, the current value, the power value, and the torque command value are increased by the amount of driving of the separation roller 13, and the inclination is larger than that in the region (1).

  Further, when the rotation speed of the first motor 11m is increased, the peripheral speed Vf of the fixing roller 12 also exceeds the peripheral speed Vp of the pressure roller 14, and the relationship between the peripheral speeds of the rollers is Vs> Vf> Vp. It becomes a relationship (region (3)). As a result, the one-way clutches 18a, 22a are both clutched in the first drive mechanism 11s to transmit the drive of the first motor 11m to the fixing roller 12 and the separation roller 13, and the driving amount of the fixing roller 12 and the separation roller 13 is increased. As a result, the torque of the first motor 11m, that is, the current value, the power value, and the torque command value increase rapidly, and the gradient becomes larger than that in the region (2).

  Here, in the region (1), the separation roller 13 rotates along with the rotation of the pressure roller 14 and has no effect of pulling the fixing belt 11, so that the intermediate region of the nip portion N1 (the first nip portion and the second nip portion). The fixing belt 11 sags and the nip pressure is insufficient, and as a result, the finish after fixing is distorted (fixed image defect). Further, since the fixing roller 12 and the separation roller 13 are rotated along with the rotation of the pressure roller 14, the load on the second motor 14m on the second drive mechanism 14s side becomes very large, which is not preferable.

  Further, in the area (3), the fixing roller 12 rotates faster than the pressure roller 14, so that a relative speed difference is generated between the fixing belt 11 and the pressure roller 14, and the fixed image is rubbed. (Fixed image defect). In addition, since both of them rotate with the pressure roller 14 digging into a thick heat-resistant elastic layer made of foamed silicon rubber or the like in the fixing roller 12, the linear velocity on the fixing roller 12 side is likely to fluctuate, and the rotation of the roller does not occur. It tends to be unstable. Therefore, when the fixing roller 12 and the pressure roller 14 are driven separately as in the area (3), the variation in the rotation of the fixing roller 12 is influenced by the large variation. The load on each of the first motor 11m and the second motor 14m increases, which is not preferable.

  In the area (2), these problems are improved. That is, first, since Vp> Vf, the fixing roller 12 rotates with the rotation of the pressure roller 14, so that the rotation of the fixing roller 12 becomes stable, and the relative relationship between the two is Since there is no speed difference, fixed image defects such as rubbing can be prevented. Further, since the fixing roller 12 and the pressure roller 14 are governed by the driving of the second drive mechanism 14 s and the influence of the variation in the rotation of the fixing roller 12 is eliminated, an extra amount is added to the first motor 11 m and the second motor 14 m. There is no heavy load.

  In the region (2), since the relationship of Vs> Vp is satisfied, the separation roller 13 is in a state of rotating faster than the pressure roller 14. At this time, since the separation roller 13 is a roller having a smaller diameter than the fixing roller 12 and has a relationship of Vp> Vf, the conveyance speed in the nip portion N1 is dominated by the rotation speed of the pressure roller 14. In addition, the respective surfaces of the contact portion (first nip portion) between the fixing belt 11 and the pressure roller 14 have the same speed. Accordingly, the separation roller 13 rotates while sliding on the inner surface of the fixing belt 11 while pulling the fixing belt 11 to some extent with respect to the first nip portion. As a result, the rotation of the separation roller 13 pulls the fixing belt 11 to set the nip pressure in the intermediate region of the nip portion N1 to a predetermined pressure, and it is possible to prevent fixed image defects such as distorted skin. In order to pull the fixing belt 11 moderately in this way, the friction coefficient between the surface of the separation roller 13 and the fixing belt 11 may be considered. For example, the separation roller 13 may be a silicon rubber roller.

  As described above, in the relationship of the expression (1), it is possible to prevent fixed image defects such as rubbing and distorted skin, and to reduce the load on the first motor 11m and the second motor 14m, thereby improving the load balance. .

  As drive control of the first drive mechanism 11s and / or the second drive mechanism 14s in this case, for example, the peripheral speeds Vp of the fixing roller 12 and the separation roller 13 are set to be constant while the peripheral speed Vp of the pressure roller 14 is constant. The drive control of the first drive mechanism 11s is performed so as to satisfy the relationship of the relational expression (1). Alternatively, as described above, the peripheral speed of the fixing roller 12 and the separation roller 13 is configured to satisfy Vs> Vf by setting the two-stage gear 19, and therefore the peripheral speed Vp of the pressure roller 14 is set to Vs ≧ Vp>. The drive of the second drive mechanism 14s may be controlled so that the relational expression of Vf is established.

  Actually, the peripheral speed Vp of the pressure roller 14, the peripheral speed Vs of the separation roller 13, and the peripheral speed Vf of the fixing roller 12 are different from each other in a set temperature, a difference in thermal expansion of each roller, and between each roller. Since it fluctuates depending on the amount of biting, it is difficult to drive the first motor 11m and the second motor 14m so that the relationship of the expression (1) always holds, with the driving conditions of the first motor 11m and the second motor 14m being constant.

  Therefore, the first motor detection means for detecting any one of the current value, power value, and torque command value of the first motor 11m, which is a servo motor, and the first motor rotation speed change for changing the rotation speed of the first motor 11m. Means for performing feedback control on the rotation speed of the first motor so that the detection value of the first motor detection means is within a predetermined range (setting range) during conveyance of the recording medium, and the equation (1) ) (Vs ≧ Vp> Vf) is preferably satisfied. The predetermined range is a range (setting range) of the current value (or power value, torque command value) of the first motor 11m in the region (2) in FIG.

  That is, in the fixing device 5, since the relationship of FIG. 5 is established between the rotation speed of the first motor 11m and the current value (power value, torque command value), the first motor 11m is detected by the first motor detection means. Current value, power value, or torque command value is detected, and when the detection value of the first motor detection means is out of a predetermined range (setting range), the detection value is predetermined. The first motor rotation speed changing means changes the rotation speed of the first motor 11m so as to be within the range (setting range). For example, when the detected value corresponds to the area (1), the rotation speed is changed to increase the rotation speed of the first motor 11m. When the detection value corresponds to the area (3), the rotation speed of the first motor 11m is changed. Change the direction to decrease. By performing such control, the relationship of Formula (1) (Vs ≧ Vp> Vf) can be satisfied.

  Such control may always be performed when the recording medium is transported, but may be performed every time an image forming mode (gloss imparting mode, no gloss imparting mode, etc.) or after a certain period of time has elapsed. Also good.

  By the way, in the fixing device 5, it is possible to perform the control so that the relational expression (1) is satisfied only by the configuration in which the first driving mechanism 11 s includes the one-way clutch 18 a in the fixing gear 18. However, when the driving of the fixing device 5 is started, the driving of the second driving mechanism 14s on the pressure roller 14 side and the first driving mechanism 11s on the fixing belt 11 side is started. The first motor 11m and the joint gear 11g are not necessarily in a completely connected state, and may be connected after the first motor 11m starts driving and starts rotating to some extent. Therefore, at the start of the driving, there is a considerable time lag in the driving rotation of the pressure roller 14 and the rollers on the fixing belt 11 side (fixing roller 12 and separation roller 13). However, there is a possibility that the fixing belt 11 and the separation roller 13 receive the shearing force. In order to avoid this, it is preferable to provide the one-way gear 22 with a one-way clutch 22a. That is, at the start of driving, the second driving mechanism 14s rotates the pressure roller 14, and the fixing roller 12 and the separation roller 13 are rotated by the action of the one-way clutches 18a and 22a. The inconvenience as described above can be avoided by performing the control for starting the driving of the one driving mechanism 11s.

Next, the configuration of the image forming apparatus according to the present invention will be described with reference to the drawings.
FIG. 6 is a schematic cross-sectional view showing the overall configuration of a digital color copying machine main body which is an aspect of the image forming apparatus according to the present invention.
The color copying machine 100 includes an image reading unit 100A located at the upper part of the apparatus main body, an image forming part 200B located at the central part of the apparatus main body, and a paper feeding unit 200C located at the lower part of the apparatus main body.

  The image reading unit 100A includes a scanner unit 1 that optically reads image information of a document, and an ADF (automatic document feeder) 101 that continuously conveys the document to the scanner unit 1.

  A belt-like intermediate transfer member 30 having a transfer surface extending in the horizontal direction is arranged in the image forming unit 100B. An image of a color complementary to the color separation color is displayed on the upper surface of the intermediate transfer member 30. A configuration for forming is provided. That is, four photoconductors 31 as image carriers capable of carrying an image of toners of complementary colors (yellow, magenta, cyan, black) are juxtaposed along the transfer surface of the intermediate transfer member 30.

  A writing unit 2 that irradiates the peripheral surface of each photoconductor 31 with exposure light based on scanner image information and external image information is disposed above the photoconductor 31. Each photoreceptor 31 is composed of a drum that can rotate in the same direction (counterclockwise direction). Around the drum, a charging device, a developing device, and a primary transfer that perform image forming processing in the rotation process. A developing unit 3 composed of an apparatus and a cleaning unit 36 that collects residual toner on the photoconductor 31 after transfer are disposed. In addition, each color toner is accommodated in each developing device.

  The intermediate transfer member 30 is configured to be wound around a driving roller and a driven roller and move in the same direction at a position facing each photoconductor 31. Further, a secondary transfer portion 34 that is a transfer roller is provided at a position facing one of the driven rollers. Further, on the paper conveyance pass line from the position of the secondary transfer unit 34, the conveyance belt 35, the fixing device 5, the gloss applying device 6, and the conveyance roller pair 7 are arranged in this order.

  The paper feed unit 200C includes a paper feed tray 41 (having 41a, 41b, 41c, and 41d as each paper feed tray) on which sheets as recording media are stacked, and the paper in the paper feed tray 41 from the top. The conveyance mechanism 37 includes a conveyance path 37 that sequentially separates the sheets one by one and conveys them to the position of the secondary transfer unit, and a registration unit 38 that performs image formation timing and skew correction.

  In forming an image in the image forming apparatus 100 of the present invention, the surface of the photoreceptor 31 is uniformly charged by the charging device of the developing unit 3, and writing is performed based on scanner image information from the image reading unit 100A or external image information. The electrostatic latent image corresponding to the color is formed on each photoconductor 31 by the unit 2. The electrostatic latent image is visualized as a toner image by a developing device containing toner of the corresponding color, and the toner image is primary on the intermediate transfer member 30 by a primary transfer device to which a predetermined bias is applied. Transcribed. As a result, the toner images of the respective colors are sequentially transferred and superimposed on the intermediate transfer body 30 by electrostatic force.

Next, the toner image primarily transferred onto the intermediate transfer body 30 is transferred to the sheet conveyed by the secondary transfer unit 34. The sheet on which the toner image has been transferred is further conveyed to the fixing device 5 and is fixed at the fixing nip portion between the fixing member (fixing belt) and the pressure member (pressure roller). Next, the fixing toner on the paper is glossed by the glossing device 6 as necessary, transported by the transport roller pair 7, and sent out from the paper discharge unit 8 along the discharge path, as an output image. A series of image forming processes are completed by discharging from the apparatus main body.
As described above, the image forming apparatus shown in FIG. 6 has advanced fixing and glossing functions, and is capable of handling various types of paper (from thin paper to thick paper) and images (glossing and no glossing). It is possible without reducing the sex.

  In addition, since the image forming apparatus according to the present invention includes the fixing device 5 of the present invention, an abnormal image that tends to occur in the nip of the intermediate region of the nip portion N1 in the fixing device 5 is different in mode depending on the type of paper or through. Stable image formation that does not occur due to a difference in the state in the paper can be performed. Further, the gloss applying device 6 is provided downstream of the fixing device 5 to perform the gloss control. However, here too, drive control described later can prevent problems such as image distortion and paper wrinkles.

FIG. 7 is a schematic diagram showing a main configuration of the image forming apparatus (color copying machine) shown in FIG.
An image forming apparatus 100 according to the present invention is an image forming apparatus having a mode for imparting gloss to an image on a sheet and a mode for imparting no gloss, and includes a fixing member (fixing belt 11) that is rotatably provided, and A fixing device (fixing device 5) having a pressure member (pressure roller 14) that forms a nip portion N1 that presses against the fixing member to fix the toner onto the paper, and a first unit having a heating means (heating member 85). A gloss applying device (gloss applying device) having a rotating body (heating roller 80) and a second rotating body (pressure roller 90) that presses against the first rotating body so as to form a nip portion N2 that gives gloss to fixing toner. 6) and a conveying roller pair (conveying roller pair 7) that is disposed within a distance L1 of 210 mm from the rear end of the nip portion of the fixing device, and conveys the sheet, on one sheet conveying pass line PL. It is as it has in turn.

  Here, in the case of the mode in which the image on the paper is not glossy, and when the length of the paper is less than 210 mm, the gloss imparting device 6 applies the nip pressure of the pressure roller 90 to the heating roller 80. The sheet is transported by lowering the nip pressure of the pressure roller 90 to the heating roller 80 in the glossing mode. When the length of the paper is 210 mm or more, the gloss applying device 6 opens the space between the heating roller 80 and the pressure roller 90, and the transport roller pair 7 transports the paper.

(Fixing device)
The fixing device 5 has the configuration shown in FIG. 1, and the surface of the fixing belt 11 is heated to a predetermined temperature in a state where the fixing belt 11 and the pressure roller 14 are rotationally driven, and the nip portion N1. The sheet on which the unfixed toner T is formed is passed through (sheet passing from the right side to the left side in the figure), and the unfixed toner is thermally fused onto the sheet by pressurization and heating in the nip portion N1 to fix the sheet. Done. Next, the toner-fixed paper is discharged from the nip portion N1, but the paper is separated from the pressure roller 14 by the separating member 43 and discharged.

  At this time, as described above, the first drive mechanism 11 s and the second drive mechanism 14 s are controlled so that the relationship of the expression (1) is established, so that fixed image defects such as rubbing and distortion skin can be prevented and the first drive mechanism 11 s can be prevented. It is possible to reduce the load on the first motor 11m and the second motor 14m and improve the load balance.

  The sheet discharged from the fixing device 5 is then sent to the gloss applying device 6. For example, two plate-like members are arranged above and below the pass line PL between the fixing device 5 and the gloss applying device 6. It is preferable to provide a guide plate 45 that narrows the gap through which the conveyed paper passes from the fixing device 5 toward the gloss applying device 6. Although the paper separated by the curvature of the separation roller 13 tends to curl, the guide plate 45 corrects the paper curl and the like so that the leading edge of the paper faces in the transport direction. Jam can be prevented and the conveyance quality can be stabilized. In the present invention, the toner on the paper is sufficiently fixed by the fixing device 5, so that the image quality is not impaired even if it contacts the guide plate 45.

(Glossing device)
The gloss imparting device 6 forms a hollow cylindrical first rotating body (heating roller 80) having a heating means (heating member 85) therein, and a nip portion N2 that imparts gloss to an image (fixing toner) on a sheet. A second rotating body (pressure roller 90) that is capable of being in pressure contact with the first rotating body.

  In addition, a temperature detection sensor 82 that detects a surface temperature close to the entry side of the nip portion N2 of the heating roller 80 is provided, and a heater such as a halogen heater that is the heating unit 85 based on the temperature detected by the temperature detection sensor 82 Is turned on, and the surface temperature of the heating roller 80 is kept constant.

  The surface temperature of the heating roller 80 is a temperature that is controlled in order to appropriately impart gloss to the fixing toner in the mode for imparting gloss to the image. For example, the surface temperature of the heating roller 80 that contacts the fixing toner on the sheet is lower than the surface temperature of the fixing member (fixing belt 11) of the fixing device 5. Alternatively, the surface temperature of the heating roller 80 is preferably not less than the sheet temperature when the sheet enters the gloss applying device 6 and not more than the sheet temperature immediately after the sheet is discharged from the fixing device 5.

Alternatively, the surface temperature of the heating roller 80 is preferably not less than the softening temperature of the toner used by the flow tester and not more than ½ outflow start temperature, and more preferably not less than the softening temperature and not more than the outflow start temperature. Here, the physical properties of these toners are, for example, using a flow tester (CFT-500D (manufactured by Shimadzu Corporation)), a load of 5 kg / cm ² , a temperature rising rate of 3.0 ° C./min, a die diameter of 1.00 mm, a die It is good to measure on condition of length 10.0mm and to obtain | require from the relationship of the piston stroke with respect to temperature. The 1/2 outflow start temperature is a temperature that is the midpoint between the outflow start temperature and the outflow end temperature.

  Specifically, the surface temperature of the heating roller 80 is preferably 60 ° C. (softening temperature at the physical property temperature of the toner used) to 137 ° C. (1/2 outflow start temperature at the physical property temperature of the toner used), and preferably 60 to 120 ° C. (use) The outflow start temperature at the physical property temperature of the toner is preferred, and more preferably 80 to 100 ° C. The temperature related to the toner (toner physical property temperature) varies depending on the toner lot and color, and the temperature shown here is an average value.

  In the present invention, when the toner passes through the fixing device 5 (fixing step), the unfixed toner on the sheet receives heat and pressure at the nip portion N1, and the entire toner layer is melted from the toner surface to the sheet. This completes the fixing. Further, the toner comes into close contact with the paper with a certain leveling, and a strong adhesive force is generated on the toner surface.

  On the other hand, since the fixing has already been completed when passing through the gloss applying device 6 (gloss applying step), an amount of heat sufficient to level the toner surface is applied. The toner on the paper that has entered the gloss imparting device 6 receives heat and pressure at the nip portion N2, but the surface temperature of the heating roller 80 is equal to or higher than the paper temperature when the paper enters the gloss imparting device 6, and from the fixing device 5. Since the temperature is equal to or lower than the paper temperature immediately after the paper is discharged (or higher than the softening temperature of the toner used by a flow tester and lower than or equal to 1/2 outflow start temperature, or 60 to 120 ° C.), the entire toner layer is melted. Instead, only the surface layer is softened, and the color as a toner is maintained as it is, while only the surface layer is leveled by the smooth surface of the heating roller 80 to improve the gloss. Since the toner surface at this time does not have the same adhesive strength as that in the fixing step, the separation property of the paper is good even if the diameter of the heating roller 80 is 30 mm or more and 40 mm or less. That is, the separating member 83 provided on the paper discharge side of the gloss applying device 6 can be omitted, and the cost can be reduced by simplifying the device configuration. Further, since the offset due to melting of the entire toner layer does not occur unlike the fixing step, the cleaning member 93 for removing the toner contamination on the surface of the pressure roller 90 can be omitted, and the apparatus configuration is simplified. Cost reduction is possible.

  The pressure roller 90 is a cylindrical roller in which an elastic layer such as silicon rubber is usually provided on a core metal such as aluminum or iron. The pressure roller 90 is provided with pressure adjusting means including a pressure lever 96, a spring 97, a pressure member 96a, and a cam 98. In the mode for giving gloss to the image, this pressure adjustment is performed. The pressure roller 90 is brought into a pressure state by the means.

  As the operation, first, when the cam 98 is rotated by a constant rotation angle in the direction of the arrow in the drawing by an external driving force, the cam 98 pushes up the pressure member 96a (in the direction of the arrow in the drawing). When the pressure member 96a is pushed, the spring 97 fixed to the pressure member 96a pushes up the end of the pressure lever 96 with a constant pressure. Next, when the end of the pressure lever 96 on the spring 97 side is pushed up, the pressure lever 96 rotates about the support shaft 96b (clockwise direction in FIG. 7). Next, the end of the pressure lever 96 on the spring 97 side and the pressure portion 96c in the middle of the support shaft 96b abuts against the shaft of the pressure roller 90 and acts to push in the direction of the heating roller 80. Finally, the pressure roller 90 comes into contact with the heating roller 80 and is pressed with a predetermined pressure, thereby forming a gloss-applying nip N2. Note that the spring 97 can be omitted as the pressure adjusting means, and in this case, the cam 98 acts to directly push up the end of the pressure lever 96.

  The pressure adjustment by the pressure adjusting means is performed by adjusting the rotation angle of the cam 98, and the heating roller 80 and the pressure roller 90 can be separated at a predetermined rotation position of the cam 98 to open the nip portion N2. It is.

Note that the nip pressure at the nip portion N2 is preferably adjusted to 15 to 30 N / cm ² by the pressure adjusting means in the mode for imparting gloss to the image on the paper. Thus, when the sheet conveyed from the fixing device 5 passes through the gloss applying device 6, the fixing toner surface layer is leveled by applying heat to the fixing toner and applying a predetermined pressure at the nip portion N2. This is done to give gloss.

When the gloss is not applied and the sheet length is less than 210 mm, the nip pressure at the nip portion N2 is higher than the nip pressure at the nip portion N2 in the gloss applying mode by the pressure adjusting unit. Is also adjusted low. For example, it is preferable to be adjusted to less than 15N / cm ^2, it is more preferably adjusted to 5N / cm ² or less. The nip pressure at this time is an average value of the entire nip width. As a result, the sheet is nipped by the heating roller 80 and the pressure roller 90. However, since the nip pressure is weak, the sheet functions as an apparatus that only conveys the sheet without increasing the gloss of the image.

  Further, when the gloss is not applied and the length of the sheet is 210 mm or more, it is preferable that the gap between the heating roller 80 and the pressure roller 90 (nip portion N2) is opened by the pressure adjusting unit.

In the mode that does not give gloss, a sheet such as an A3 plate having a weight of 80 g / m ² or less may be used as a thin paper longitudinal paper. In this case, the sheet between the fixing device 5 and the gloss applying device 6 is used. Even a slight difference in the linear velocity of the paper causes fine wrinkles or the like on the paper due to bending or tension. Therefore, this problem is solved by separating the heating roller 80 and the pressure roller 90 of the gloss applying device 6. At this time, the paper only passes through the glossing device 6, but since the length of the paper is 210 mm or more, the leading edge of the paper coming out from the nip portion N1 of the fixing device 5 reaches the conveying roller pair 7, The conveying roller pair 7 nips and conveys the sheet. As a result, it is possible to reduce the chance of the roller coming into contact with the formed image to ensure image quality and to reliably convey the image.

  Further, the distance between the heating roller 80 and the pressure roller 90 (the gap between the rollers) when opening is preferably 2 mm or less. This is because if the gap between the rollers is larger than 2 mm, the sheet is easily detached from the pass line PL and jamming is likely to occur.

  In addition, it is preferable to coat | cover each surface layer of the heating roller 80 and the pressure roller 90 with a fluororesin. According to this, when the gap between the rollers is set to 2 mm or less and the heating roller 80 and the pressure roller 90 are separated from each other in the mode in which the gloss is not given, and the sheet is passed through the gap, the image surface is the heating roller 80. However, since the fluororesin layer 80a on the surface has releasability, the occurrence of image shaving or the like can be prevented even if the image partially contacts.

  By configuring the gloss applicator 6 as described above, the target gloss can be stably obtained in the mode for imparting gloss, and the reliability of the target gloss in each of the mode for imparting gloss and the mode for not imparting gloss. Has improved.

  Further, as the arrangement position of the gloss applicator 6, the distance L2 from the rear end of the nip portion N1 of the fixing device 5 to the front end of the nip portion N2 of the gloss applicator 6 is more preferably 70 to 182 mm. It is preferable that the heating roller 80 and the pressure roller 90 are arranged so as to be ˜150 mm, more preferably 80 to 100 mm. When the distance L2 is less than 60 mm, since the distance between the entrance side and the exit side of the two plate members of the guide plate 45 is determined, the inclination of the plate member becomes too steep and the guide plate 45 is jammed. Is likely to occur and is not suitable. The upper limit of the distance L2 is preferably the minimum sheet length. For example, the distance L2 = 182 mm is a distance to cope with the case where the short direction of the B5 plate paper is transported as the transport direction. In addition, when the half-letter size paper is transported in the short direction, the upper limit of the distance L2 is 150 mm.

FIG. 8 shows the configuration of the drive mechanism in the fixing device 5 and the gloss applying device 6. The driving mechanism of the fixing device 5 is the same as that shown in FIG.
Here, the gloss applying device 6 includes a third motor 80m corresponding to the heating roller 80 and a drive transmission system 80t having a joint gear 80g, one or a plurality of drive transmission gears. A third drive mechanism 80 s for transmitting the drive to the heating roller 80 is provided.

  The third motor 80m is provided on the image forming apparatus main body side, and when the gloss imparting device 6 is mounted on the image forming apparatus main body, the third motor 80m and a joint gear 80g which is a drive input portion of the heating roller 80, Are concatenated.

  With this configuration, the drive of the third motor 80m is transmitted to the heating roller 80 by the drive transmission system 80t via the joint gear 80g, and the gloss applying device 6 is driven. Here, the configuration in which the third drive mechanism 80s drives the heating roller 80 is shown, but the third drive mechanism 80s may drive the pressure roller 90.

Here, when the conveyance speed of the recording medium in the fixing device 5 is V1, and the conveyance speed of the gloss applying device 6 is V2, the drive control in the third drive mechanism 80s is performed so that the following relational expression (2) is satisfied. Are preferred.
1.05 × V1 ≧ V2 ≧ V1 (2)

  In FIG. 9, in the gloss applying device 6 that receives the recording medium transported from the fixing device 5 at a predetermined transport speed V1, the rotational speed of the third motor 80m and the current value (or power value, torque command) of the third motor 80m. Value). In the figure, the relationship between the recording medium conveyance speed V1 in the fixing device 5 and the recording medium conveyance speed V2 in the gloss applying device 6 is also shown.

  The relationship between the rotational speed of the third motor 80m and the current value (or power value, torque command value) is basically proportional to the current value increasing as the rotational speed increases. It can be divided into three regions according to the magnitude relationship between V1 and V2.

  That is, when the rotation speed of the third motor 80m is small, the relationship of the recording medium conveyance speed is V1> V2, the conveyance speed V1 in the fixing device 5 becomes dominant, and the torque, that is, the current and power of the third motor 80m are The torque command value is small (region (I)). In the region (I), even if the rotation speed of the third motor 80m increases, the current value, power value, and torque command value increase only slightly. Here, the torque command value is a torque value to be output by the third motor 80m that is instructed to the controller of the third motor 80m from the drive system controller of the gloss applying device 6.

  Next, when the number of rotations of the third motor 80m is increased, the conveyance speed V2 in the gloss applying device 6 exceeds the conveyance speed V1 in the fixing device 5, and a relationship of 1.05 * V1> V2> V1 is established ( Region (II)). Further, when the conveyance speed V2 further increases, the relationship of V2> 1.05 * V1 is satisfied (region (III)). In these areas (II) and (III), the torque of the third motor 80m, that is, the rate of increase (slope) of the current value, power value, and torque command value is the same and is larger than that in area (I).

  Here, in the region (I), the speed (V1) carried in from the fixing device 5 is larger than the speed (V2) at which the recording medium is discharged in the gloss applying device 6, and therefore the fixing device 5 and the gloss applying device 6 are used. In the meantime, the recording medium undulates and loosens, and the recording medium or the image has a problem that sagging occurs. On the other hand, in the region (III), since the speed (V2) at which the gloss imparting device 6 ejects the recording medium is too larger than the speed (V1) carried in from the fixing device 5, the recording medium is pulled strongly. Or, there is a problem that wrinkles extending obliquely from the edge of the recording medium called the rib bone wrinkles occur in the image in the center direction.

  In the region (II), the gloss imparting device 6 improves the problem of sagging and ribs by appropriately pulling the recording medium. That is, as shown in the relationship of Expression (2), the conveyance speed V2 in the gloss imparting device 6 is set to be within + 5% with respect to the conveyance speed V1 in the fixing device 5, thereby preventing appearance defects such as sagging and ribs. be able to.

  Actually, the conveyance speeds V1 and V2 of the fixing device 5 and the gloss applying device 6 vary depending on the set temperature, the thermal expansion of each roller, the amount of biting between the rollers, and the paper type. Therefore, it is difficult to drive so that the relationship of Expression (2) is satisfied with each driving condition being constant.

  Therefore, third motor detection means for detecting any one of the current value, power value, and torque command value of the third motor 80m, and third motor rotation speed changing means for changing the rotation speed of the third motor 80m, And during the recording medium conveyance, feedback control is performed on the rotational speed of the third motor 80m so that the detection value of the third motor detection means is within a predetermined range, and Expression (2) (1.05 × V1) It is preferable to satisfy the relationship of ≧ V2 ≧ V1). The predetermined range is a range (set range) of the current value (or power value, torque command value) of the third motor 80m in the region (II) in FIG.

  That is, in the gloss applying device 6, since the relationship of FIG. 9 is established between the rotational speed of the third motor 80m and the current value (power value, torque command value), the third motor detection means causes the third motor to be detected. If any of the 80 m current value, power value, and torque command value is detected and the detection value of the third motor detection means is out of a predetermined range (setting range), the detection value is The third motor rotation speed changing means changes the rotation speed of the third motor 80m so as to be within a predetermined range (setting range). For example, when the detected value corresponds to the region (I), the rotational speed of the third motor 80m is changed to increase, and when the detected value corresponds to the region (III), the rotational speed of the third motor 80m is changed. Change the direction to decrease. By performing such control, the relationship of Expression (2) (1.05 × V1 ≧ V2 ≧ V1) can be established.

  Such control may always be performed when the recording medium is transported as long as the heating roller 80 and the pressure roller 90 are in pressure contact with each other in the gloss applying device 6, but the image forming mode (gloss imparting mode) may be used. , Mode in which no gloss is applied, etc.) or after a certain period of time.

  The paper discharged from or passed through the gloss imparting device 6 is then sent to the transport roller pair 7. For example, two plate-like members pass between the gloss imparting device 6 and the transport roller pair 7. It is preferable to provide a guide plate 95 that is disposed above and below the PL and narrows the gap through which the conveyed sheet passes from the gloss applying device 6 toward the conveying roller pair 7. Since the guide plate 95 corrects the curling of the paper and the front end of the paper is directed in the carrying direction, wrinkles and jams at the carrying roller pair 7 can be prevented, and the carrying quality can be stabilized.

(Conveying roller pair)
The conveying roller pair 7 has a configuration in which a cylindrical roller 7a made of chloroprene rubber or silicon rubber and a cylindrical roller 7b made of resin are in contact with each other. One or both of the rollers 7a and 7b are rotationally driven, and the conveyed paper is sandwiched and conveyed to the discharge path. Here, since the conveyance roller pair 7 is disposed within 210 mm from the rear end of the nip portion N1 of the fixing device 5, it is a mode in which the image is not glossy and the length in the sheet conveyance direction is 210 mm ( In the case where the length of the A4 plate paper is shorter than the length of the A4 plate paper, the gap between the heating roller 80 and the pressure roller 90 of the gloss imparting device 6 is open, but the leading edge of the paper exiting the nip N1 of the fixing device 5 is Since the trailing edge of the sheet reaches the conveying roller pair 7 before exiting the nip portion N1, the sheet can be appropriately conveyed.

  In the present invention, the surface temperature of the heating roller 80 is low in the gloss imparting device 6 (above the paper temperature when the paper enters the gloss imparting device 6 and below the paper temperature immediately after the paper is discharged from the fixing device 5 (or use When the toner reaches the conveying roller pair 7 in the mode for imparting gloss, the softening temperature is higher than the softening temperature by the flow tester and is equal to or lower than the ½ outflow start temperature (or 60 to 120 ° C.). The sheet temperature is equal to or less than the sheet temperature immediately after the sheet is discharged from the fixing device 5 and can prevent the toner from adhering to the conveying roller pair 7. For the same reason, the guide plate 95 is also provided. It is also possible to prevent toner sticking to the toner.

(Glossing mode / Glossless mode)
In the image forming apparatus 100 of the present invention, using the same continuous weight (weighing) of paper, a mode for imparting gloss to the image on the paper (gloss imparting mode) and a mode for not imparting gloss (non-gloss imparting mode). And can be selected. For example, the gloss display mode and the non-gloss mode are displayed on the display monitor of the image forming apparatus 100 so that the user can select them. Here, the gloss imparting mode means that an image (fixed toner image) is formed using a paper with high glossiness (30 to 50%) such as coated paper, and is equivalent to the paper that is the base for the image. This is a mode for imparting gloss and is suitable for gravure photo printing. The non-gloss mode is a mode in which an image is formed using a sheet such as plain paper that does not have a very high gloss level, and a process for giving gloss to the image is not performed. Here, the glossiness is a value (%) measured with a 60 ° gloss meter.

When the gloss imparting mode is selected, the following processing is performed using coated paper having a glossiness of 30 to 50% as the paper. Here, the description will be made on the assumption of the apparatus configuration of FIG.
(S11) The sheet on which the unfixed toner is placed is conveyed, and the fixing device 5 fixes the toner. At this time, the fixing belt 11 is heated to a temperature suitable for toner fixing by the heat generated by the heater 15 h disposed inside the heating roller 15. Regarding the nip pressure in the nip portion N1, the cam 78 of the pressurizing means is adjusted so that the ratio of the region where the nip pressure in the entire nip width is 15 to 30 N / cm ² is 50% or more. As a result, the toner on the paper that has passed through the fixing device 5 is completely fixed, and the image (fixed toner) is given a gloss of 25% or more.
(S 12) The paper discharged from the fixing device 5 is curled and corrected by the guide plate 45, and the leading edge of the paper is appropriately fed into the gloss applying device 6.
(S13) In the gloss imparting device 6, gloss is further imparted to the image on the paper. At this time, the surface temperature of the heating roller 80 is 80 to 100 ° C., and the nip pressure of the nip portion N2 is adjusted to 15 to 30 N / cm ² by the pressure adjusting means. As a result, when the paper passes through the gloss applying device 6, heat and a predetermined pressure are applied to the fixing toner at the nip portion N2, and the fixing toner surface layer is leveled so that the gloss of the paper is ± Glossiness within 15%, more preferably within ± 10%, is imparted to the fixing toner.
(S14) The paper discharged from the gloss applying device 6 is discharged through the guide plate 95 and the transport roller pair 7 through the transport path.

When the glossy non-granting mode is selected, the size of the paper is confirmed, and the length in the transport direction of the paper is divided into less than 210 mm and more than 210 mm, and processing is performed as follows.
First, a case where the length in the paper transport direction is less than 210 mm will be described.
(S21) The sheet on which the unfixed toner is placed is conveyed, and the fixing device 5 fixes the toner. At this time, the fixing belt 11 is heated to a temperature suitable for toner fixing by the heat generated by the heater 15 h disposed inside the heating roller 15. Regarding the nip pressure at the nip portion N1, the cam 78 of the pressurizing means is adjusted so that the ratio of the region where the nip pressure in the entire nip width is 15 to 30 N / cm ² is less than 50%. As a result, the toner is completely fixed in a state where the gloss of the image (fixed toner) on the paper that has passed through the fixing device 5 does not increase so much. Alternatively, depending on the type of paper, the conditions of the fixing device 5 may be the same as those in the glossing mode.
(S22) The curling of the paper discharged from the fixing device 5 is corrected by the guide plate 45, and the leading edge of the paper is appropriately fed into the gloss applying device 6.
(S23) In the gloss applying device 6, the sheet is sandwiched by the nip portion N2 and conveyed. At this time, the surface temperature of the heating roller 80 is 80 to 100 ° C., but the nip pressure of the nip portion N2 is lower than the nip pressure of the nip portion N2 in the gloss imparting mode by the pressure adjusting means, for example, 5 N / It is adjusted to cm ² or less. By making the pressure low in this way, when the sheet passes through the gloss applying device 6, the heat and pressure are not so much applied to the fixing toner at the nip portion N2, and the gloss of the fixing toner is not increased.
(S24) The paper discharged from the gloss applying device 6 is discharged through the guide plate 95 and the transport roller pair 7 through the transport path.

Next, when the non-gloss giving mode is selected and the length in the paper transport direction is 210 mm or more, the following processing is performed.
(S31) A sheet on which unfixed toner is placed is conveyed, and the fixing device 5 fixes the toner. At this time, the fixing belt 11 is heated to a temperature suitable for toner fixing by the heat generated by the heater 15 h disposed inside the heating roller 15. Regarding the nip pressure at the nip portion N1, the cam 78 of the pressurizing means is adjusted so that the ratio of the region where the nip pressure in the entire nip width is 15 to 30 N / cm ² is less than 50%. As a result, the toner is completely fixed in a state where the gloss of the image (fixed toner) on the paper that has passed through the fixing device 5 does not increase so much.
(S32) The paper discharged from the fixing device 5 is curled and corrected by the guide plate 45, and the leading edge of the paper is appropriately fed into the gloss applying device 6.
(S33) In the gloss applying device 6, the heating roller 80 and the pressure roller 90 are separated so that the gap between the rollers is 2 mm or less, and the sheet is between the heating roller 80 and the pressure roller 90. Going through.
(S <b> 34) The sheet that has passed through the gloss applying device 6 passes through the guide plate 95 and reaches the conveying roller pair 7. Since the transport roller pair 7 is disposed within 210 mm from the rear end of the nip portion N1 of the fixing device 5, the leading edge of the paper reaches the transport roller pair 7 before the rear end of the paper exits the nip portion N1. Then, the conveyance roller pair 7 sandwiches the sheet and continues the conveyance appropriately. The sheet that has exited the transport roller pair 7 is discharged through a transport path.

  As described above, in the non-glossing mode (for example, normal printing), the fixing device 5 and the glossing device 6 increase the gloss of the toner regardless of whether the length in the paper transport direction is less than 210 mm or more than 210 mm. Since it has been devised so that it can be conveyed stably without being raised, an image with a desired gloss can be obtained without changing the paper transport pass line in any of the glossing mode and the non-glossing mode. Therefore, the image forming apparatus can be miniaturized.

  In the gloss imparting mode, the nip time in the fixing device 5 can be 30 msec or more, more preferably 60 msec or more, and the nip time in the gloss imparting device 6 can be 15 msec or more. As a result, in the gloss imparting mode, paper productivity equivalent to that in the non-gloss imparting mode is obtained, and high productivity can be maintained regardless of which mode is selected.

Although the present invention has been described with the embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and other embodiments, additions, modifications, deletions, etc. Can be changed within the range that can be conceived, and any embodiment is included in the scope of the present invention as long as the effects and advantages of the present invention are exhibited. For example, as shown in FIG. 10, the fixing device 5 may be configured such that the tension roller 16 and the driven roller 17 are omitted.
Further, as the image forming apparatus of the present invention, the glossing device 6 is omitted from the configuration of FIGS. 6 and 7, or the second fixing device is used instead of the glossing device 6, and the fixing device 5 and the second fixing device are used. The fixing device may complete the fixing of the toner onto the paper using the two fixing devices.

DESCRIPTION OF SYMBOLS 1 Scanner part 2 Writing part 3 Developing part 5 Fixing apparatus 6 Gloss imparting apparatus 7 Conveying roller pair 7a, 7b Roller 8 Paper discharge part 11 Fixing belt 11g, 14g, 80g Joint gear 11m 1st motor 11s 1st drive mechanism 11t, 14t , 80t Drive transmission system 12 Fixing roller 13 Separating roller 14, 90 Pressure roller 14c Web cleaning unit 14h, 15h, 85 Heater (heating means)
14 m Second motor 14 s Second drive mechanism 15, 80 Heating roller 16 Tension roller 17 Driven roller 18 Fixing gear 18 a, 22 a One-way clutch 19 Two-stage gear 20 Shaft drive gear 21 Drive transmission shaft 22 One-way gear 23 Separating roller gear 24 Pressure Idler gear 25 Pressure gear 30 Intermediate transfer member 31 Photoreceptor 34 Secondary transfer part 35 Conveying belt 37 Conveying path 38 Registration part 41, 41a, 41b, 41c, 41d Feed tray 43, 44, 83 Separating member 45, 95 Guide plate 62, 72, 82 Temperature sensor 76, 96 Pressing lever 76a, 96a Pressing member 76b, 96b Support shaft 76c, 96c Pressing part 77, 97 Spring 78, 98 Cam 80m Third motor 80s Third drive mechanism 93 Cleaning 100 images Forming device 100A Image reading unit 100B Image forming unit 100C Paper feeding unit 101 Automatic document feeder (ADF)
N1, N2 Nip part P Paper (recording medium)
PL pass line T toner

JP 2004-191858 A JP 2008-185682 A

Claims (8)

A fixing roller as a driving roller;
A separation roller which is a driving roller;
An endless fixing belt spanned between the fixing roller and the separation roller;
A pressure roller that forms a nip portion in pressure contact with the fixing roller and the separation roller via the fixing belt;
The first motor has a one-way clutch, and a drive transmission system in which the peripheral speed of the separation roller is larger than the peripheral speed of the fixing roller, and the first motor is driven via the one-way clutch. A first drive mechanism that transmits to the fixing roller and transmits the drive of the first motor to the separation roller;
A second drive mechanism comprising a second motor and a drive transmission system, and transmitting the drive of the second motor to the pressure roller;
With
When the peripheral speed of the pressure roller is greater than the peripheral speed of the fixing roller, the one-way clutch is idled and the fixing roller rotates with the rotation of the pressure roller. .   When the peripheral speed of the pressure roller is greater than the peripheral speed of the fixing roller, the one-way clutch rotates idly and the fixing roller rotates along with the rotation of the pressure roller, and the separation roller The fixing device according to claim 1, wherein the fixing device is driven and rotated by one driving mechanism.   The first drive mechanism causes the drive transmission system to idle when the peripheral speed of the pressure roller is greater than the peripheral speed of the separation roller, and the separation roller rotates with the rotation of the pressure roller. The fixing device according to claim 2, further comprising a second one-way clutch. When the peripheral speed of the pressure roller is Vp, and the peripheral speed of the fixing roller and the separation roller when the one-way clutch is locked is Vf, Vs,
4. The drive control of the first drive mechanism and / or the second drive mechanism is performed so that a relationship of Vs ≧ Vp> Vf is established during conveyance of the recording medium. The fixing device described. First motor detection means for detecting any of the current value, power value, and torque command value of the first motor;
First motor rotation speed changing means for changing the rotation speed of the first motor,
Feedback control is performed on the rotational speed of the first motor so that the detection value of the first motor detection means is within a predetermined range during conveyance of the recording medium, and the relationship of Vs ≧ Vp> Vf is established. The fixing device according to claim 4.   An image forming apparatus comprising the fixing device according to claim 1. A gloss applying device comprising: a heating member; a pressure member that presses against the heating member to form a nip portion; and a third drive mechanism that includes a third motor that rotates the heating member or the pressure member. Provided downstream of the fixing device in the recording medium conveyance direction,
When the conveyance speed of the recording medium in the fixing device is V1, and the conveyance speed in the gloss applying device is V2,
The image forming apparatus according to claim 6, wherein drive control in the third drive mechanism is performed so that a relationship of 1.05 × V1 ≧ V2 ≧ V1 is established. Third motor detection means for detecting any of a current value, a power value, and a torque command value of the third motor;
A third motor rotation speed changing means for changing the rotation speed of the third motor,
During the conveyance of the recording medium, feedback control is performed on the rotation speed of the third motor so that the detection value of the third motor detection means is within a predetermined range, and the relationship of 1.05 × V1 ≧ V2 ≧ V1 is established. The image forming apparatus according to claim 7, wherein:

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