JP2016004107A - Glossing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a difference in temperature between an image surface and a rear surface of a recording sheet, during cooling the image surface of the recording sheet for adding gloss after passing through a fixing nip, in any situation of a continuous sheet passing immediately after the start of sheet passing, thereby to reduce a sheet curling occurrence.SOLUTION: A glossing device includes: a belt stretched on a plurality of rollers; a heat source for heating the belt; a pressure member that comes into pressure contact from the outside of the belt to form a fixing nip section; and a belt inside cooling device and a belt outside cooling device arranged in a cooling section located downstream of the pressure member in a belt traveling direction. An image surface of a recording sheet is brought into contact with the belt at the fixing nip section, and the recording sheet is conveyed. The cooling device cools the recording sheet and separates it. A temperature of the pressure member is acquired. A cooling output of the belt outside cooling device is controlled according to the temperature.

Description

  The present invention relates to a gloss imparting device that is installed inside or outside an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine thereof, or is installed separately from the image forming apparatus. The present invention relates to a gloss imparting device that imparts gloss to a fixed image on a recording material (hereinafter also referred to as recording paper), and includes a cooling device that cools the fixed image.

  2. Description of the Related Art Conventionally, there has been known a gloss applying device that makes an image having high gloss with respect to an image obtained by an image forming apparatus using an electrophotographic system. This comprises an endless belt stretched around a plurality of rollers, a pressure roller provided facing the belt stretch roller, and a cooling means for cooling the recording paper in contact with the belt. ing. The toner or resin member is melted once at the nip formed by the belt stretching roller and the pressure roller via the belt, and the toner / resin member and the belt are brought into close contact with each other. It is transported, cooled in a close contact state, and peeled off at the peeling portion. By doing so, the surface state of the belt is transferred to the surface of the toner / resin member, the surface of the toner / resin member becomes smooth, and an image having a high glossiness such as a photograph is obtained.

  For example, in Patent Document 1, in order to cool the recording paper brought into contact with the endless belt, a cooling fan is installed on the inner side of the endless belt and the outer side (lower side) of the endless belt, and is cooled by blowing air from the cooling fan. Is disclosed. A method of cooling by contacting a heat pipe or a heat sink containing water or other refrigerant is also disclosed. Also in Patent Document 2, it is disclosed that a cooling fan is installed on the outer side (lower side) of the endless belt and is cooled by blowing air from the cooling fan. At that time, it is also described that a required glossy image or non-glossy image is obtained by adjusting the air volume of the cooling fan. Patent Document 3 discloses a technique in which gloss is imparted to an electrophotographic image that has been formed and fixed by a method of performing fixing processing at the same time as transferring, by cooling to a temperature below the melting temperature with a cooling device, and then peeled off from the conveying belt. Has been. Patent Document 4 discloses a configuration in which transparent toner is transferred to an electrophotographic image that has been image-formed and fixed (temporarily) fixed later, and gloss is obtained by cooling and peeling. In Patent Document 6 (the image surface faces upward), a thermoplastic transparent resin member is pressed on the belt circumference before the nip portion between the belt member and the pressure roller, and this resin member is converted into an electrophotographic image at the nip portion. A configuration in which transfer is performed and cooling peeling is performed is disclosed. Both of these provide cooling and glossing with the image surface facing upward. However, Patent Document 6 discloses a glossing device in which the cooling means is disposed facing the recording paper with the image surface facing downward. Is disclosed.

  As described above, various types of gloss imparting apparatuses are known. Further, since the gloss variation can be suppressed by stabilizing the cooling effect of the cooling process, it is also known to control the temperature of the cooling process. It is also known that desired glossiness can be obtained by changing the amount of heat applied to the recording paper. For this purpose, there are a method of applying heat at a high temperature and a method of adjusting the amount of applied heat by making the length of the heat transfer region variable.

  The process of cooling to give gloss to the image surface is because the glossy fixing nip softens the glossy transparent toner or the colored toner after fixing, and the image surface sticks to the belt via the toner. This is because the image surface (recording paper) is detached from the belt. As the temperature of the recording paper is lowered during separation from the belt, the toner resin stringing phenomenon can be reduced, the surface roughness of the toner image can be reduced, and the glossiness can be increased. The cooling is first directed to the image surface of the recording paper.

  On the other hand, since the cooling of the back surface of the recording paper (the side opposite to the belt surface) is not essential, a temperature difference may occur between the front and back of the recording paper, and paper curling may occur. If the fixing temperature of the toner is lowered to suppress the temperature difference, there is a problem that smoothing becomes insufficient and the image glossiness is deteriorated. For this reason, it is necessary to secure the fixing temperature for glossing to a level sufficient for smoothing.

  Generally, the surface temperature of the pressure roller is low at the start of gloss application, and the temperature difference between the front and back of the recording paper is relatively small even if the recording paper is cooled from the belt side after passing through the fixing nip. However, since the pressure roller gradually accumulates heat when the paper is continuously passed, heat is applied to the back side of the recording paper when it passes through the fixing nip, and the temperature rises on the back side of the recording paper. The temperature difference between the front and back of the paper increases and the possibility of paper curling increases. In order to cope with the temperature rise of the pressure roller, a configuration including a cooling device dedicated to the pressure roller is also known, and the pressure roller is cooled by this dedicated cooling device, resulting in heat storage during continuous paper feeding. It is also conceivable to suppress the temperature rise on the back side of the recording paper. However, if this is done, the pressure roller is supercooled and the fixing roller / belt is also cooled between the sheets, so that the output of the heat source for heating the fixing roller / belt must be increased. obtain.

  In the present invention, the temperature difference between the image surface and the back surface of the recording paper is reduced while the image surface of the recording paper is being cooled in order to give gloss after passing through the fixing nip, in any case of continuous paper feeding immediately after the start of paper feeding. The purpose is to reduce the occurrence of paper curl.

  The above-described problems include a belt wound around a plurality of rollers, a heat source that heats the belt, a pressure member that presses from the outer peripheral side of the belt to form a fixing nip portion, and a belt that is more than the pressure member. A belt inner peripheral side cooling device and a belt outer peripheral side cooling device arranged in a cooling unit on the downstream side in the running direction, and conveying the image surface of the recording paper in contact with the belt at the fixing nip portion; In the gloss applying device that cools and peels off the recording paper by the device, the temperature of the pressing member is acquired, and the cooling output of the belt outer peripheral side cooling device is controlled according to the temperature.

  According to the present invention, the cooling output of the belt outer peripheral side cooling device is controlled by acquiring the temperature of the pressure member and substituting the temperature with the back surface temperature of the recording paper. And the temperature difference between the back side and the back side can be reduced to suppress the occurrence of paper curl. In particular, even if the temperature of the pressure member rises due to heat accumulation during continuous paper feeding, the cooling output of the cooling member on the back side of the recording paper can be increased to appropriately lower the temperature on the back side of the recording paper that has received heat from the pressure member. As a result, the temperature difference between the front side and the back side of the recording paper can be reduced. Generation can be reduced.

It is a schematic block diagram of the glossiness imparting apparatus which conveys an original image upward and gives glossiness. It is a schematic block diagram of the glossiness imparting apparatus which conveys an original image face down and gives glossiness. FIG. 3 is a schematic diagram illustrating an example of a gloss applying device installed externally as a peripheral device of an image forming apparatus.

  FIG. 1 shows a schematic diagram of a gloss imparting device in which the original image surface (gloss imparting surface) faces upward and contacts the belt as a first embodiment of the present invention. This gloss imparting device is a combination of transfer fixing technology and cooling peeling technology, and is configured to impart gloss to an arbitrary portion of a recording sheet on which an electrophotographic image is produced. In such an apparatus for obtaining a partially glossy image, the user designates and selects an arbitrary position of the original image to perform partial high gloss processing, and a high gloss image comparable to the stencil printing technology can be easily obtained. .

  The gloss applying apparatus is not connected to a normal image forming apparatus and functions as an independent apparatus. For this purpose, a document reading device 50 and an original image automatic paper feeding device 20 are installed for reading original image data of a document and sending it to the touch panel display 10. The touch panel display for displaying the original image data and designating the glossy part can be provided separately from the glossing device, for example, a personal computer connected by wire or wirelessly. The document reading device 50 includes a scanner 51 that reads an image surface of a document through a glass plate on which a document (which may be a recording sheet obtained by copying an original image) is placed, and a pressure plate 52 that presses the document against the glass plate. ing. The original image data read by the document reading device 50 is taken into the touch panel display 10, displays the original image on the screen, and arbitrarily designates an area, a line, or a figure to be given gloss on the display screen. The designated information is transmitted to the glossy image forming system 30 from a CPU (not shown). The interface software connected to the CPU may have a drawing function, and new characters and figures can be created and added.

  The original image automatic paper feeder 20 accommodates a recording sheet that already has a toner image corresponding to the original image data and is to be glossed. The original image automatic paper feeding device 20 has a paper feed tray 21 for stacking recording paper having an original image, a pickup roller 22 for feeding and transporting the stacked recording paper in order, and a transport roller 23, and a paper transport unit 24. The recording sheet is conveyed to the sheet discharge tray 25 after being given gloss. In addition to the original image automatic paper feeding device 20, a manual paper feed mechanism having a known configuration may be provided. Via the route of the manual paper feed mechanism, it may be connected to the fixing unit and the subsequent part of a normal image forming apparatus. In that case, when the gloss mode is selected in the image forming apparatus, the image forming apparatus The recording paper is transported to the gloss applying apparatus of this example by switching the paper transport path.

  The gloss image forming system 30 has basically the same configuration as a conventional electrophotographic image forming apparatus, and can be considered to be different in that the toner used is a glossy colorless transparent toner. In other words, in the gloss image forming system, the surface of the photoreceptor 31 is uniformly charged by the charging device 32, exposed by the exposure device 33 to form a gloss latent image, and developed by the developing device 35 with the gloss toner. The developed gloss information is transferred onto the endless belt 4. The transfer residual gloss toner is collected from the belt 4 by the cleaning member 33.

  On the other hand, the gloss imparting mechanism includes an endless belt 4 wound around the fixing roller 1 and the separation roller 5, a pressure roller 3 that presses against the fixing roller 1 across the belt, and an inner peripheral side and an outer peripheral side of the belt. And a cooling device arranged respectively. The belt 4 is a member that conveys the recording paper to the left in the drawing in a state where the image surface of the recording paper is opposed to the belt. Although not shown, the pressure roller 3 is configured to be separable and has a dedicated cooling device 6 so that the optimum cooling efficiency can be selected according to the required production speed. The cooling method may be an air cooling method, a water cooling method, or a mixing method thereof. Further, the pressure roller 3 is provided with a pressure roller temperature sensor 7 (thermistor, thermopile, etc .; preferably a non-contact type) so that the surface temperature can be detected and acquired. After the fixing nip between the fixing roller 1 and the pressure roller 3 with the belt 4 interposed therebetween, the recording paper on which the gloss toner is fixed is cooled on both sides of the upper image surface (gloss imparting surface) and the lower back surface. Cooled by. The separation roller 5 for separating the curvature of the recording paper also serves as a transfer function in the gloss image forming system. At the contact portion between the separation roller 5 and the photosensitive member 31 with the belt 4 interposed therebetween, the gloss toner on the photosensitive member is transferred to the belt 4. Transcript to. In this example, transfer is performed with 31 directly contacting the endless belt 4, but an intermediate transfer member may be interposed.

  Here, the belt 4 is a belt having a two-layer structure of a base material and a surface layer formed on the outer peripheral surface side. A resin sheet having high heat resistance can be used as the belt base material. Polymer sheets such as polyester, polyethylene, polyethylene terephthalate, polyethersulfone, polyetherketone, polysulfone, polyimide, polyamideimide, and polyamide can be used. In this example, polyimide is used. The belt base material has, for example, a thickness of 10 to 300 μm and a linear expansion coefficient of 20 ppm or less. As the belt surface layer, a material such as silicone resin or fluorine resin can be used, and has a thickness of 1 to 100 μm, for example.

  Further, since the belt 4 is used to give gloss to the image on the recording paper, the surface (the front side of the surface layer) is formed as a smooth surface suitable for giving high gloss. In this case, the smooth surface is formed such that, for example, the arithmetic average roughness Ra is 0.3 μm or less, preferably 0.1 μm or less. The fixing roller 1 or the separation roller 5 (both in some cases) around which the belt 4 is wound generates a driving force as a driving roller, and rotates the belt 4 at a peripheral speed of about 20 to 700 mm / second. .

  The fixing roller 1 fixes the gloss toner onto the recording paper with the pressure roller 3 and is a hollow roller having an outer diameter of about 30 to 200 mm made of a metal material having high thermal conductivity such as aluminum. A halogen heater 2 is fixed inside the cylindrical body as a heat source, and both ends thereof are fixed to a side plate (not shown) of the gloss imparting device. The output control of the halogen heater 2 is performed based on the detection result of the belt surface temperature by a temperature sensor 8 (thermistor, thermopile, etc .; preferably non-contact type) disposed on the outer peripheral side of the belt 4. By such heater output control, the surface temperature of the belt 4 in the portion stretched around the fixing roller 1 is a desired temperature suitable for the fixing process (above the melting point of the glossy toner, about 50 ° C. to 200 ° C.). Adjusted to The heat source of the fixing roller 1 may be a heat pipe extending in the longitudinal direction for heat balance, or may be an IH system or the like.

  The pressure roller 3 that forms the fixing nip and the fixing roller 1 with the belt 4 interposed therebetween forms an elastic layer of silicone rubber having a thickness of about 2 to 30 mm on the outer periphery of a cylindrical metal core, The surface layer is laminated. The surface layer is composed of, for example, a fluororesin tube having a thickness of about 30 to 200 μm. The width of the fixing nip formed by the pressure roller 3 and the fixing roller 1 by pressure contact by a not-shown separation mechanism is set to about 6 to 40 mm.

  Of the cooling devices disposed downstream of the fixing nip portion in the belt traveling direction / downstream of the recording paper conveyance direction, the belt outer peripheral cooling device 14 is constituted by a cooling fan, and not only cools the belt 4 from the outer peripheral side. The back side opposite to the image side (glossy side) of the recording paper is directly cooled. The recording paper sticks to the surface of the belt 4 by the melted gloss toner and may be separated from the belt 4 by gravity as it is cooled. However, the recording paper is pressed against the belt 4 while being transported by the outer cooling device 14. Maintained. On the other hand, the belt inner peripheral side cooling device 15 is configured as a known liquid cooling system having a cooling member fixed so as to be close to or rubbed with the belt, and cools the belt 4 from the inner peripheral side. The cooling member may be pressed against the inner peripheral surface of the belt in order to enhance the adhesion as the surface cooling by increasing the adhesion between the cooling member of the inner peripheral cooling device 15 and the belt. The cooling member is made of a metal material having high thermal conductivity such as aluminum. For example, a flow path in which a coolant such as water reciprocates in a zigzag manner is formed in the cooling member. The cooling member is connected to a heat radiation unit (not shown) separated from the belt, and the liquid cooling system is also provided with a cooling liquid storage tank and a pump. Both the cooling devices 14 and 15 are not limited to those of the present example, and a known cooling mechanism can be adopted, but in any case, the belt outer peripheral side cooling device 14 is more than the belt inner peripheral side cooling device 15. The cooling performance is low. In addition, the cooling devices 14 and 15 are independently turned on / off based on the detection results of the temperature sensors 7 and 8 corresponding to the cooling devices 14 and 15 to make the cooling effect variable. That is, when it is desired to cool to a temperature lower than the detected temperature based on the temperatures detected by the temperature sensors 7 and 8, respectively, the rotational speed of the cooling fan is increased or the liquid cooling is increased in order to increase the cooling output accordingly. Adjust to increase the circulation and heat dissipation of the system coolant. If there is a temperature difference between the front and back of the recording paper, it will cause deformation of expansion and contraction in the recording paper, causing a "paper curl" phenomenon that the paper will be rounded in one direction, and the quality of the paper is not good. The cooling devices 14 and 15 are individually controlled based on the detection results 7 and 8. A plurality of cooling devices 14 and 15 may be installed along the belt running direction.

  In such a gloss imparting device, gloss is imparted to the toner image on the recording paper as the original image as follows. Original image information read by the document reading device 50 is taken into the touch panel display 10, and an area, a line, or a figure to be given glossiness is arbitrarily designated from the display 100 by the user for the original image information. The designated information is transmitted from a CPU (not shown) to the gloss image forming system 30, and based on the information, a gloss image with gloss toner is formed on the photoreceptor 31 by the gloss image forming system 30, and transferred. The toner is transferred to the belt 4 by a separation roller 5 as a means.

  The glossy image on the belt 4 travels to the fixing nip as the belt 4 travels. In the fixing roller 1 forming the fixing nip portion, therefore, the belt 4 is controlled to an appropriate temperature by the temperature sensor 8, and the toner D of the gloss image is in an appropriate melting state when passing through the fixing nip portion. Can do. On the other hand, a recording sheet having a toner image corresponding to the original image data is conveyed from the original image automatic paper feeder 20 to the fixing nip portion in accordance with the glossy image on the belt 4.

  In the fixing nip portion, the melted gloss toner D is fixed on the recording paper. At this time, the gloss toner image on the recording paper is given high smoothness by the belt surface having high smoothness. Further, the fixing temperature T is lower than the glass transition temperature TgB of the toner of the original image (T <TgB), and does not deteriorate the original image or give the original image itself gloss. The recording paper heated and pressurized at the fixing nip and stuck to the belt 4 by the melted gloss toner is cooled to an appropriate temperature by the cooling devices 14 and 15 until reaching the position of the separation roller 5, and thereafter Then, it is peeled off by the curvature separation at the position of the separation roller 5 and discharged out of the apparatus. The glossy toner image cooled in the state of being in close contact with the belt 4 is cooled and solidified to a glass transition point of the toner, for example, 40 ° C. or less when separated from the belt. The state is transferred to the surface of the glossy toner image and high gloss is obtained. The glossiness (20 ° glossiness) is, for example, about 65-80.

  In addition, in order to detect and acquire the belt temperature in the cooling unit, the first belt temperature sensor 12 ′ is disposed at the most upstream side position of the belt inner peripheral side cooling device 15 immediately after the exit of the fixing nip unit. A second belt temperature sensor 12 ″ is provided at a position on the most downstream side of the side cooling device 15. In the illustrated example, the belt temperature sensors 12 ′ and 12 ″ are disposed on the inner peripheral side of the belt 4, that is, Although it is arranged in the belt body (belt back side), it may be arranged on the outer periphery side of the belt (outside of the sheet passing area if it is a contact type sensor). In this case, since the outer peripheral surface of the belt is in contact with the image surface of the recording paper, it is preferable to use a non-contact type thermistor, thermopile, or radiation thermometer as the sensor. If the temperature sensor is arranged on the outer peripheral side of the belt in this way, the temperature of the belt surface, that is, the screen side of the recording paper and the back side of the recording paper can be detected simultaneously. By directly detecting the back surface temperature of the recording paper, more accurate back surface temperature control is possible. Furthermore, the belt temperature information can be acquired in detail by providing temperature sensors at a plurality of places where the belt temperatures are different. By installing a belt temperature sensor at the most downstream side of the belt inner peripheral side cooling device 15, that is, at the cooling outlet, it is possible to know to what degree the belt has been cooled while passing through the cooling region. By feeding back this information to the cooling output value of the belt outer peripheral side cooling device 14 on the back side of the recording paper, it is possible to minimize the temperature difference between the front and back of the recording paper with higher accuracy. As for how much the belt is cooled, the heat capacity varies depending on the paper thickness, so acquiring the belt temperature at both the inlet and outlet of the cooling area determines how much the back side of the recording paper should be cooled. It is important to do. When the belt temperature sensor is arranged on the outer peripheral side of the belt, by using a non-contact sensor, it is possible to directly detect the temperature on the back side of the recording paper as well as the belt surface. By controlling the cooling output of the belt outer peripheral side cooling device 14 on the back side of the recording paper according to the acquired back side temperature of the recording paper, the back side of the recording paper can be cooled with higher accuracy. The temperature difference between the front and the back of the paper can be minimized to prevent the occurrence of paper curl.

  FIG. 2 shows a schematic diagram of a gloss imparting device that abuts against the belt with the original image surface (gloss imparting surface) facing downward (gravity direction) as a second embodiment of the present invention. Compared with the gloss applying device shown in FIG. 1, this gloss applying device has a fixing roller 1 and a pressure roller 3 that constitute a fixing nip portion positioned upside down. This is the same as the gloss applying device. Accordingly, the same members and apparatus configurations are denoted by the same reference numerals, and the description thereof is omitted. Since the recording paper is placed on the endless belt 4 and conveyed after the fixing nip portion has passed, there is no fear of dropping. Further, since the gloss image forming system is located below the endless belt, toner scattering from the image forming system is also reduced.

  2, the endless belt 4 of the gloss applying mechanism is wound around the fixing roller 1, the separation roller 5, and the transfer roller 36 of the gloss image forming system. In addition, two cooling fans, which are the belt outer peripheral side cooling devices 14 ′ and 14 ″ arranged downstream of the fixing nip portion in the recording paper conveyance direction, are installed. A cooling effect can be obtained, and by controlling the output of the plurality of cooling devices independently of each other, finer cooling control can be performed, such as a belt or the like near the cooling zone inlet. Since the temperature of the recording paper is still high, the cooling output is increased and rapidly cooled to a certain temperature or less, and the cooling proceeds considerably near the exit of the cooling area. In addition, the plurality of cooling devices are divided not only in the upstream and downstream of the recording paper conveyance direction but also in the longitudinal direction of the roller perpendicular to the conveyance direction. In this case, for example, when a wide recording sheet is passed, the cooling device in the entire longitudinal direction is operated, and when a narrow recording sheet (for example, a postcard) is passed, Fine control such as operating only the corresponding cooling device is possible, and this fine control also saves energy.

  FIG. 3 shows a third embodiment of the present invention. This is one in which a gloss applying device is incorporated as a post-processing device in an image forming apparatus. The overall structure of the image forming apparatus is known as the prior art, and a predetermined apparatus necessary for forming an image around the photosensitive member, for example, a charging unit, an exposure unit, a developing unit, etc. is provided. Yes. The “image forming apparatus” depicted in FIG. 3 has such an image forming apparatus as an image forming unit, and is a so-called quadruple tandem type indirect transfer type full-color image forming apparatus, and transports recording paper vertically. The paper is discharged face down. Such a color image forming apparatus is well known to those skilled in the art without needing to be described. The gloss imparting device to which the color image on the intermediate transfer belt is transferred after being transferred to the recording paper has already been described with reference to FIG. 2, and compared with FIG. The only difference is that it does not have a paper feeder. Therefore, for the glossiness imparting apparatus here, the description in FIG. 2 can be referred to by adding a reference number for simplification of the description.

DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Halogen heater 3 Pressure roller 4 Belt 5 Separation roller 6 Cooling device only for pressure roller 7, 8 Temperature sensor 14 Belt outer peripheral side cooling device 15 Belt inner peripheral side cooling device

Japanese Patent No. 5241155 Japanese Patent Laid-Open No. 05-333634 JP 2002-099159 A Japanese Patent No. 4442265 JP 2011-197370 A JP 2011-197370 A

Claims (8)

A belt wound around a plurality of rollers, a heat source that heats the belt, a pressure member that forms a fixing nip portion by pressing from the outer peripheral side of the belt, and a downstream side in the belt traveling direction from the fixing nip portion A belt inner peripheral side cooling device and a belt outer peripheral side cooling device disposed in the cooling unit of the recording medium, and conveys the image surface of the recording paper in contact with the belt at the fixing nip portion, and the cooling device records the recording paper. In the gloss imparting device that cools and peels
A gloss applying device that acquires the temperature of the pressure member and controls the cooling output of the belt outer peripheral side cooling device in accordance with the temperature.   The gloss applying device according to claim 1, wherein the temperature of the belt in the cooling unit is acquired, and the cooling output of the belt outer peripheral side cooling device is controlled according to the temperature.   The gloss applying device according to claim 2, wherein the temperature of the belt in the cooling unit is acquired at a plurality of locations in the belt traveling direction. A belt wound around a plurality of rollers, a heat source that heats the belt, a pressure member that forms a fixing nip portion by pressing from the outer peripheral side of the belt, and a downstream side in the belt traveling direction from the fixing nip portion A belt inner peripheral side cooling device and a belt outer peripheral side cooling device disposed in the cooling unit of the recording medium, and conveys the image surface of the recording paper in contact with the belt at the fixing nip portion, and the cooling device records the recording paper. In the gloss imparting device that cools and peels
Gloss imparting characterized in that the temperature of the back surface of the belt and the recording paper is acquired between the fixing nip portion and the cooling portion, and the cooling output of the belt outer peripheral side cooling device is controlled according to these temperatures. apparatus.   The gloss applying apparatus according to claim 4, wherein temperatures of the back surface of the belt and the recording paper are acquired on an upstream side and a downstream side in the belt traveling direction in the cooling unit.   The gloss applying device according to any one of claims 1 to 5, wherein a plurality of belt inner peripheral side cooling devices and / or belt outer peripheral side cooling devices are provided.   The gloss applying device according to claim 6, wherein cooling outputs of the plurality of belt inner peripheral side cooling devices and / or belt outer peripheral side cooling devices are controlled independently of each other.   An image forming apparatus comprising the gloss applying device according to claim 1.

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