JP4829693B2 - Gloss improvement device - Google Patents

Description

  The present invention relates to a gloss improving apparatus for improving the gloss of an image formed on a recording material. Specifically, the present invention relates to a gloss improving apparatus that improves the gloss of an image formed on a recording material by heating a toner image formed on a resin layer on the surface of the recording material and then cooling the toner image.

  2. Description of the Related Art Conventionally, image forming apparatuses using an electrophotographic system, such as copying machines, printers, facsimiles, and multi-function machines, are widely known. Many products that form not only black-and-white images but also full-color images have been commercialized.

  In addition, as image forming apparatuses are used in various fields, the demand for image quality is becoming higher and higher.

  Here, the glossiness of an image has attracted attention as an element for improving the quality of an image formed on a recording material. One factor for improving the glossiness of the image is the smoothness of the image.

  It has been proposed to improve the smoothness of an image by forming a toner image on a recording material provided with a transparent resin layer made of a thermoplastic resin as a toner receiving layer and embedding the toner image in the resin layer (Patent Document 1). ).

  It has been proposed to use a fixing belt as an apparatus for improving the smoothness of such an image (Patent Document 2). In this apparatus, the resin layer is softened together with the toner image by heating and pressurizing with the fixing belt, and then the recording material moving while being in close contact with the fixing belt is cooled by the cooling mechanism and then the recording material is peeled off from the fixing belt. Have taken.

  As a result, the toner image is embedded in the transparent resin layer of the recording material, and the entire surface of the recording material becomes a smooth surface, so that an image having excellent glossiness can be obtained.

Also, a belt fixing device similar to that described above for improving the glossiness of an image formed on plain paper has been proposed (Patent Document 3). In this belt fixing device, the recording material is cooled from the inside and outside of the fixing belt.
JP 2003-084477 A JP 2004-205563 A JP-A-5-46050

  However, in the apparatuses of Patent Documents 2 and 3, since the cooling region by the cooling mechanism is set closer to the separation position rather than the fixing nip, there is a possibility that the problem of “blister” described below may occur.

  The problem of this blister is a phenomenon in which the above-mentioned transparent resin layer coated on the paper base material of the recording material is partially pushed up and deformed in the form of fire. This is considered to be due to the fact that the water present inside the paper base material is vaporized by the heat applied to the recording material, the volume rapidly expands, and a large amount of water vapor passes through the resin layer. .

  In addition to such a phenomenon, there may be a phenomenon in which a part of the toner image is lost in the form of bubbles due to water vapor generated in the paper base material.

  These phenomena are mainly caused by the heat applied to the recording material. However, if the heat applied to the recording material is reduced, it is difficult to properly embed the toner image in the resin layer.

  Therefore, the present invention has been made in view of such technical problems. An object of the invention is to provide a gloss improving device capable of improving the glossiness of an image while suppressing the phenomenon that the resin layer of the recording material is deformed.

According to the present invention, the above object can be achieved. The present invention provides a belt for heating a toner image formed on a resin layer on the surface of a recording material at a nip portion, a heating member for heating the belt from the inside at the nip portion, and the belt toward the heating member. In the gloss improving apparatus, comprising: a pressure member that pressurizes and a cooling unit that cools the heated recording material that moves while being in close contact with the belt from the inner surface side of the belt and the outer surface side to which the recording material is in close contact;
The cooling region from the outer surface side of the belt is set closer to the nip portion than the cooling region from the inner surface side of the belt.

  According to the present invention, it is possible to improve the glossiness of an image while suppressing the phenomenon that the resin layer of the recording material is deformed.

  Next, examples to which the present invention can be applied will be described in detail. In addition, unless there is particular description about each structure demonstrated below, there is no intent to limit to the specific structure. That is, it goes without saying that it can be replaced with another configuration having a similar function.

(1) Image Forming Unit A color image forming apparatus employing an electrophotographic method will be briefly described with reference to FIG.

  In this example, electrophotographic photosensitive drums 3a to 3d are provided as image carriers, and toner images of respective colors are formed on the photosensitive drum drums 3a to 3d. The toner images are formed by the developing devices 1a to 1d. Specifically, the developing devices 1a to 1d contain cyan toner, magenta toner, yellow toner, and black toner as developers, and have a function of developing an electrostatic image formed on the photosensitive drum.

  The toner images of the respective colors formed on the photosensitive drums 3 a to 3 d are sequentially transferred onto the recording material P conveyed by the transfer belt 130. The transfer of the toner image is performed by transfer chargers 24a to 24d, respectively.

  The recording material P is accommodated in the recording material cassette 10 and is conveyed from there to the registration roller 12 by the conveying roller. Then, the registration roller starts to convey the recording material toward the transfer belt 130 so as to synchronize with the toner image on the photosensitive drum.

  Next, the recording material P to which the toner image has been transferred is separated from the transfer belt 130, and the separated recording material P is conveyed to the fixing device 9 by the conveyance unit 62.

  Further, the recording material P on which the toner images of the respective colors are transferred is heated and pressurized by the fixing device 9 to fix the toner images.

  Thereafter, in the image forming mode in which the glossing process is not performed, the recording material is discharged out of the apparatus as it is. On the other hand, as will be described later, in the case of the image forming mode in which the glossing process is performed, the recording material is conveyed to the gloss improving apparatus F, subjected to the glossing process, and then discharged outside the apparatus.

  Note that such a glossing process is performed by the gloss improvement device F described below when using a recording material (hereinafter referred to as photomedia) in which an image forming layer is formed of a transparent thermoplastic resin as will be described later. . This photo media is used to form a high gloss image such as a silver lead photograph.

(2) Glossiness improvement device F
FIG. 2 shows an enlarged model diagram of the gloss improvement apparatus F. The gloss improving device F in this embodiment is a so-called belt fixing device.

  The belt fixing device includes a fixing roller 51 as a heating member, a separation roller 53 disposed at a predetermined distance from the fixing roller 51, and a tension roller 54 disposed above the separation roller 53. Have. Further, an auxiliary roller 55 is provided in contact with the outer surface of the fixing belt at a position near the separation roller 53 between the fixing roller 51 and the separation roller 53. The fixing roller 51, the pressure roller 52, the separation roller 53, the tension roller 54, and the auxiliary roller 55 are arranged substantially in parallel with each other. The tension roller 54 applies a predetermined tension to the fixing belt 57.

  Further, it has an endless fixing belt 57 suspended by these three rollers 51, 53 and 54. In this example, as will be described later, heating and pressurization at the fixing nip N soften the transparent resin layer on the surface of the photo media along with the toner image to make the entire surface of the photo media a smooth surface. Has been.

  In order to obtain a glossy image such as a silver-lead photograph, it is preferable to set the glossiness of the belt surface (contact surface with the photo media) to 60 or more. In addition, if the intensity of the reflected light from the light source (fluorescent lamp or the like) reflected by the photomedia is too uncomfortable, it is preferable to set the belt glossiness to 120 or less. That is, the glossiness of the belt is preferably set to 60 or more and 120 or less. In order to obtain an image having a gloss level comparable to that of a silver-lead photograph, it is more preferable to set the gloss level of the belt to 80 or more and 100 or less. In this example, the glossiness of the belt is set to 95.

  The glossiness (60 °) of the surface of the belt was measured using a handy gloss meter (PG-1M) manufactured by Nippon Denshoku Industries Co., Ltd. (based on JIS Z 8741). At this time, the incident angle of light to the belt was set to 60 °.

  Further, the belt fixing device has a pressure roller 52 as a pressure member provided so as to sandwich the fixing belt 57 with the fixing roller 51. When the pressure roller 52 presses the fixing belt 57 toward the fixing roller 51, a fixing nip N (nip portion) is formed between the fixing belt 57 and the pressure roller 52.

  The fixing roller 51 has a concentric three-layer structure, and has a core portion, an elastic layer, and a release layer. The core portion is composed of an aluminum hollow pipe having a diameter of 44 mm and a thickness of 5 mm. The elastic layer is made of silicon rubber having a JIS-A hardness of 50 degrees and a thickness of 300 μm. The release layer is made of PFA resin having a thickness of 50 μm. A halogen lamp 58 as a heating source is disposed inside the hollow pipe of the core portion.

  The pressure roller 52 has the same configuration. The elastic layer is made of silicon rubber having a thickness of 3 mm. This is because the elastic layer increases the length of the fixing nip. A halogen lamp 59 as a heating source is disposed inside the hollow pipe in the core portion of the pressure roller 52. The pressure applied by the pressure roller 52 was 490 N (50 kgf) in total pressure. At this time, the width of the fixing nip N in the recording material conveyance direction was 5 mm.

  The fixing roller 51 is rotationally driven at a predetermined speed in a clockwise direction indicated by an arrow by a driving mechanism (not shown). As the fixing roller 51 rotates, the fixing belt 57 rotates in the clockwise direction indicated by the arrow. The separation roller 53, the tension roller 54, the pressure roller 52, and the auxiliary roller 55 are driven to rotate as the fixing belt 57 rotates.

  In starting the fixing process, electric power is supplied to the halogen lamps 58 and 59 disposed inside the fixing roller 51 and the pressure roller 52, respectively, and the surface temperatures of the fixing roller 51 and the pressure roller 52 are increased.

  The surface temperatures of the fixing roller 51 and the pressure roller 52 are respectively detected by a thermistor (not shown), and the detected temperatures of these thermistors are fed back to a control circuit (not shown). The control circuit controls the electric power supplied to the halogen lamps 58 and 59 so that the detected temperature input from each thermistor becomes a predetermined target temperature set for each of the fixing roller 51 and the pressure roller 52. That is, the temperature of the fixing roller 51 and the pressure roller 52 are controlled to the respective target temperatures, and the temperature of the fixing nip portion N is controlled to a predetermined fixing temperature (160 degrees in this example).

(3) Cooling Mechanism of Gloss Improvement Device F In this example, a cooling mechanism (cooling means) that cools the front and back sides of the photo media that have passed through the fixing nip N and moved in close contact with the fixing belt before separation from the fixing belt. ) 61 and 62 are provided.

  The cooling mechanism 61 is installed inside the fixing belt 57 and is configured to cool the front side (image surface side) of the photo media. Specifically, the cooling mechanism 61 has a duct extending in a direction perpendicular to the recording material conveyance direction (arrow direction in FIG. 2), and a cooling fan installed on one end side of the duct for supplying air into the duct. is doing.

  The cooling mechanism 62 is installed outside the fixing belt 57 and is configured to cool the back side of the recording material. Specifically, the cooling mechanism 62 has a duct extending in a direction perpendicular to the recording material conveyance direction (arrow direction in FIG. 2), and a cooling fan installed on one end side of the duct and supplying air into the duct. is doing.

  Needless to say, the cooling mechanisms 61 and 62 are not limited to the above-described example, and a contact-type cooling system is also possible. For example, a Peltier element, a heat pipe, or a circulating water cooling device may be used.

(4) Glossy Image Forming Mode for Glossing Processing In this example, as described above, in addition to the normal image forming mode in which the recording material such as plain paper fixed by the fixing device 9 is discharged to the outside as it is. Has a glossy image forming mode. When this glossy image forming mode is selected, the photo media subjected to the hypothetical process in the fixing device 9 is introduced into the gloss improving device F, subjected to the glossing process, and then discharged outside the apparatus.

  This glossy image forming mode is configured to be selected automatically by the apparatus or in accordance with an instruction from the operator when the recording material to be used is a photo media.

  Next, the image forming process in the glossy image forming mode will be described in order.

  First, when the operation unit of the image forming apparatus selects and instructs that the type of the recording material is photo media, the image forming mode is switched to the glossy image forming mode.

  Then, a full color toner image is formed on the photo media in the image forming unit described above, and the full color toner image is assumed on the photo media by the fixing device 9.

  The photomedia on which the toner image is assumed is conveyed to the belt fixing device F.

  Then, the photo media is introduced into the fixing nip N so that the toner image surface of the photo media contacts the surface of the fixing belt 57.

  The photo media is heated and pressurized in the process of being nipped and conveyed through the fixing nip N, whereby the color toner images are mixed and embedded in the transparent resin layer.

  Thereafter, the photo media is conveyed from the fixing nip N to the separation position (position where the separation roller 53 is disposed) through the cooling region R as the fixing belt 57 rotates while keeping in close contact with the fixing belt 57.

  During this conveyance, the photo media is cooled in the cooling region R by the cooling mechanisms 61 and 62. Specifically, in the cooling region R, the photo media is forcibly and efficiently cooled by the action of the air flow flowing through the cooling fans 61 and 62 and the air duct surrounding the cooling fans 61 and 62.

  Thus, the photo media in close contact with the surface of the fixing belt 57 is sufficiently cooled in the cooling region R so as to be near the glass transition temperature of the toner (about 50 ° C.) and reaches the separation position. The photo media is separated (curvature separation) from the surface of the fixing belt 57 by its own rigidity (strain) at a separation position where the curvature of the fixing belt 57 changes greatly by the separation roller 53.

  As a result, the surface (resin layer) of the photo media is smoothed according to the surface shape of the fixing belt without the resin or toner of the photo media being offset to the fixing belt side.

  The auxiliary roller 55 prevents the photo media from being peeled off the surface of the fixing belt 57 in the middle of the fixing belt conveyance region from the fixing nip N to the separation position.

  FIG. 3A shows a state before the glossing process is performed on the toner image formed on the photo medium. a is a paper substrate of the photo media P, b is a transparent resin layer, and t is a toner image. FIG. 3B shows a state after the glossing process in which the toner image is properly embedded in the resin layer. ta represents a toner image embedded in the resin layer b. In this way, the toner image is solidified together with the photomedia resin along the mirror-like belt surface, and the entire surface of the photomedia becomes a smooth surface, so that an image with excellent gloss can be obtained.

  Next, the photo media used in this example will be described in more detail.

  The most characteristic feature of this photo media is that the outermost transparent resin layer (also referred to as a toner receiving layer) melts near the fixing temperature. As a result, when the toner image is fixed on the photo media, the toner image is embedded in the toner receiving layer, so that the level difference due to the toner is reduced.

  As a specific example of the photo media, it is desirable to form a transparent resin layer on the white pigment coating layer.

  As a result, since the lower layer has a pigment layer and a high white and smooth surface is formed, it is not necessary to add a pigment to the outermost resin layer, and the function of increasing the whiteness becomes unnecessary. For this reason, for the thermoplastic transparent resin layer on the surface, it is possible to select a material giving priority to functions such as increasing glossiness and embedding a toner image.

  As such photo media, POD Super Gloss Photo Media manufactured by Oji Paper Co., Ltd. is marketed.

  A specific example of the manufacturing method is introduced. Using the paper with the above-mentioned pigment coating layer formed on a base material as a base paper, make a desired photo media by applying a thermoplastic resin on one or both sides of the base paper using a gravure coater or the like be able to.

  As the resin constituting the transparent resin layer, a polyester resin, a styrene-acrylic ester resin, a styrene-methacrylic ester resin, or the like can be used, and it is particularly preferable to use a polyester resin. The following are illustrated as a polyhydric alcohol component and polyhydric carboxylic acid component which comprise a polyester resin.

  Polyhydric alcohol components include ethylene glycol, propylene glycol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, a monomer obtained by adding olefin oxide to bisphenol A, and the like can be used.

  Examples of the polyvalent carboxylic acid component include maleic acid, maleic anhydride, fumaric acid, phthalic acid, terephthalic acid, isophthalic acid, malonic acid, succinic acid, glutaric acid, dodecyl succinic acid, n-octyl succinic acid, and n-dodecyl succinic acid. Acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxy-2 -Methyl-2-methylenecarboxypropane, tetra (methylenecarboxy) methane, 1,2,7,8-octanetetracarboxylic acid, trimellitic acid, pyromellitic acid, lower alkyl esters of these acids, and the like can be used. .

  The polyester resin constituting the transparent resin layer is synthesized by polymerization of one or more of the polyhydric alcohol components and one or more of the polyvalent carboxylic acid components.

  As the resin component of the toner, a polyester resin is used in color toners, and a styrene-acrylic resin is mainly used in monochrome toners. It is preferable to select a highly compatible one.

  Accordingly, one or a mixture of two or more types of polyester resin, styrene-acrylic acid ester resin, styrene-methacrylic acid ester resin, or the like is used as the thermoplastic resin for the photo media.

Furthermore, the transparent resin layer can contain a pigment, a release agent, a conductive agent, and the like within a range that does not impair the transparency. In that case, it is preferable that the resin amount of the main component is 80% by weight or more based on the total weight of the resin layer. Further, the transparent resin layer preferably has a composition adjusted so that its surface electrical resistance is 8.0 × 10 ⁸ Ω or more at a temperature of 20 ° C. and a relative humidity of 85%.

  In addition, it is not limited to such a manufacturing method, and if it is a photo media provided with a thermoplastic resin layer having a melting property whose surface is melted near the fixing temperature, it is not always necessary to have a multilayer structure, such as a pigment. It goes without saying that various additives may be added.

Therefore, the photomedia used in this example has a 10 μm transparent resin layer mainly composed of polyester (thermoplastic resin) as a toner receiving layer b on one side of a base paper having a basis weight of 170 g / m ² as a base material a. The thickness is provided.

(Verification of blister)
Next, the cooling effect in the gloss improvement device F will be verified. In this example, the state in which the toner is solidified means a state in which the toner is cooled to near the glass transition temperature Tg. Specifically, the glass transition temperature of the toner is about 45 to 60 degrees.

  Since the temperature at which the viscosity of the transparent resin layer and toner of the photo media change greatly and starts to melt is about 90 to 100 degrees, the fixing nip N is preferably heated to about 100 to 120 degrees so as to exceed this temperature.

  On the other hand, in order to make the surface of the photomedia smooth, it is preferable to cool the photomedia and the fixing belt to a temperature near Tg by a cooling mechanism. In this embodiment, the cooling is performed so as to be about 50 ° C.

  If the cooling is not sufficiently performed as described above, the toner on the photo media and the transparent resin layer thereof are viscous, and therefore, there is a problem that they are not properly separated from the fixing belt. That is, even if the photo media is separated from the fixing belt, the toner and the resin of the transparent resin layer are still in a soft state, and some of them are offset to the fixing belt side at the time of separation. As a result, the image surface of the photo media that has been smoothed in accordance with the surface of the fixing belt becomes uneven at the time of separation, and the glossiness (smoothness) decreases.

  For the reasons as described above, the gloss improving apparatus F of this example employs a cooling separation method.

  Next, as a result of verification of the blister, the present inventor has found that the place where the blister occurs is not the fixing nip N but a portion of about 1 cm to 5 cm after passing through the fixing nip N.

  This is because the heat applied to the photo media does not reach the inside of the fixing nip N, and only the surface is heated. In other words, after passing through the fixing nip N, heat is gradually transferred to the inside of the photo media, and moisture of the base material is evaporated, so that it becomes a blister.

  Further, for comparison with respect to the conveyance of the photo media while being in close contact with the fixing belt, an experiment was conducted in which the fixing belt was removed and the sheet was passed between the fixing roller and the pressure roller for comparison.

  It was found that the surface temperature of the photomedia rises even after passing through the fixing nip N in the case of this example that is conveyed in close contact with the fixing belt. On the other hand, in the comparative experiment, it was found that the surface temperature of the photo media decreases immediately after passing between the rollers.

  This is presumably because the photo media is heated even after passing through the fixing nip N due to the heat stored in the fixing belt.

  Therefore, it was found that blistering measures can be taken by suppressing the temperature rise of the photo media after passing through the fixing nip N.

  Further, when the embedding of the toner into the toner receiving layer at this time was verified, it was found that the toner hardly depends on the cooling state after passing through the fixing nip N. This is presumably because the embedding of toner in the toner receiving layer is completed when pressure is applied at the fixing nip N.

  From the above experimental results, it was found that it is sufficient to cool immediately after the fixing nip N as a countermeasure against blisters.

  Therefore, the present inventor has studied to reduce the temperature of the photo media and the fixing belt immediately after passing through the fixing nip.

  In the conventional belt fixing device described above, it is possible to cope with the problem by increasing the cooling capacity of the mechanism for cooling the fixing belt from the inside, but the following problems have occurred.

  That is, when the cooling capability of the inner cooling mechanism is increased in the conventional belt fixing device, the fixing roller 51 that heats the fixing belt is cooled, so that the heating becomes insufficient and the toner is not sufficiently embedded. It has become. In this case, it is conceivable to increase the power supplied to the halogen lamp in the fixing roller in consideration of the cooling by the cooling mechanism. However, the heat from the halogen lamp is greatly lost, which is a preferable solution from the viewpoint of energy saving. It will not be.

  Therefore, in this example, in order to cope with such a problem, not only a cooling mechanism 61 that cools from the inside of the fixing belt but also a cooling mechanism 62 that cools from the outside of the fixing belt is provided.

  Further, in this example, the cooling mechanism 61 is disposed near the separation position (position sufficiently away from the fixing roller 58), while the cooling mechanism 62 is disposed near the fixing nip N (fixing roller 58). That is, the cooling area by the cooling mechanism 62 is set closer to the fixing nip N in the recording material conveyance direction than the cooling area by the cooling mechanism 61.

  Specifically, the cooling mechanism 62 cools an area 1 cm to 5 cm away from the fixing nip N in the recording material conveyance direction.

  This is because the cooling mechanism 61 prevents the fixing roller from being excessively cooled, and the cooling mechanism 62 cools the photo media and the fixing belt immediately after passing through the fixing nip, thereby preventing the occurrence of blisters. .

  As described above, by cooling the photo media immediately after passing through the fixing nip N without hindering the heating at the fixing nip N, it was possible to improve the toner embedding property and prevent the occurrence of blisters.

  FIG. 4 shows a modification of the gloss enhancing device F. In this example, except for the cooling mechanism, the other configuration is the same as that of the first embodiment, and therefore, detailed description is omitted by giving the same number to members having the same function.

  In this embodiment, a cross flow fan is employed as the cooling mechanism 62 that cools from the outside of the fixing belt, and the cooling air is directed in the direction of the arrow in the drawing. That is, the cooling air hits only a narrow area immediately after the photo media exits the fixing nip N. That is, the cooling mechanism 61 functions as a main cooler for cooling a wide area near the separation position, and the cooling mechanism 62 functions as a sub-cooler for cooling a narrow area immediately after passing through the fixing nip. That is, the cooling area of the cooling mechanism 62 is narrower than the cooling area of the cooling mechanism 61.

  By adopting such a configuration, it is possible to cool a region closer to the fixing nip N, and the blister problem can be solved at a higher level.

  FIG. 5 shows a modification of the gloss enhancing device F. In this example, except for the cooling mechanism, the other configuration is the same as that of the second embodiment, and therefore, detailed description is omitted by giving the same number to members having the same function.

  In this embodiment, a Peltier element is employed as the cooling mechanism 61 that cools from the inside of the fixing belt, and this Peltier element is arranged in contact with the fixing belt.

  In the air cooling method of the cooling mechanism 61 as in the first and second embodiments, the cooling air reaches the fixing roller 58 not a little, but such a problem does not occur if the Peltier element as in this example is used. As in the second embodiment, also in this example, the cooling mechanism 61 functions as a main cooler for cooling a wide area near the separation position, and the cooling mechanism 62 as a sub cooler cools a narrow area immediately after passing through the fixing nip. Plays a function. That is, the cooling area of the cooling mechanism 62 is narrower than the cooling area of the cooling mechanism 61.

  That is, the heating at the fixing nip N can be prevented at a higher level. Further, by cooling the photo media immediately after passing through the fixing nip N by the cooling mechanism 62, the same effect as in the above-described embodiment can be obtained.

  FIG. 6 shows a modification of the gloss enhancing device F. In this example, except for the cooling mechanism, the other configuration is the same as that of the second embodiment, and therefore, detailed description is omitted by giving the same number to members having the same function.

  In this embodiment, a heat pipe is employed as the cooling mechanism 61 that cools from the inside of the fixing belt, and the heat pipe is in contact with the fixing belt.

  Cooling refrigerant is enclosed in the heat pipe, and cooling fins are attached to one end in the longitudinal direction. The cooling fin is cooled by a cooling fan to cool the system. As in the second embodiment, also in this example, the cooling mechanism 61 functions as a main cooler for cooling a wide area near the separation position, and the cooling mechanism 62 as a sub cooler cools a narrow area immediately after passing through the fixing nip. Plays a function. That is, the cooling area of the cooling mechanism 62 is narrower than the cooling area of the cooling mechanism 61.

  Also in this example, similarly to the third example, the air cooling method of the cooling mechanism 61 as in the first and second examples does not cause a problem that the cooling air reaches the fixing roller 58.

  In addition, although the heat pipe is used in this example, it does not need to be a pipe shape, and needless to say, a block shape is also suitable.

  In addition to cooling by a fan, a water cooling system in which a water circulation pump is installed outside the belt fixing device to circulate cooling water may be adopted.

  Note that the belt fixing device as the gloss improving device described in each of the above embodiments may be a so-called optional device that can be selectively connected / disconnected to the main body of the image forming apparatus. Absent.

  In the belt fixing device F described above, an example in which a pressure roller is used has been described. However, the present invention can be similarly applied even when an endless pressure belt is used instead of the pressure roller. It is.

It is a schematic sectional drawing which shows an image forming apparatus. It is a schematic sectional drawing which shows a belt fixing device. (A) is a schematic diagram of the recording material showing a state before being fixed by the belt fixing device, and (b) is a schematic diagram of the recording material showing a state after being fixed by the belt fixing device. It is a schematic sectional drawing which shows the other example of a belt fixing device. It is a schematic sectional drawing which shows the other example of a belt fixing device. It is a schematic sectional drawing which shows the other example of a belt fixing device.

Explanation of symbols

F Belt fixing device (gloss improvement device)
DESCRIPTION OF SYMBOLS 9 Roller fixing device 10 Recording material cassette 12 Registration roller 32 Separation charger 51 Fixing roller 52 Pressure roller 53 Separation roller 54 Tension roller 55 Auxiliary roller 57 Fixing belt 58 Heater 59 Heater 61 Cooling mechanism 62 Cooling mechanism

Claims (4)

A belt that heats the toner image formed on the resin layer on the surface of the recording material at the nip, a heating member that heats the belt from the inside at the nip, and a pressure that pressurizes the belt toward the heating member. In a gloss improving apparatus, comprising: a pressure member; and a cooling unit that cools the heated recording material that moves while being in close contact with the belt from the inner surface side of the belt and the outer surface side to which the recording material is in close contact.
The gloss improving apparatus according to claim 1, wherein a cooling region from the outer surface side of the belt is set closer to the nip portion than a cooling region from the inner surface side of the belt.   2. The gloss improving apparatus according to claim 1, wherein the glossiness of the belt surface is 60 or more and 120 or less.   3. The gloss improving apparatus according to claim 1, wherein the belt softens the resin layer on the surface of the recording material together with the toner image at the nip portion.   4. The gloss improving apparatus according to claim 1, wherein the cooling means includes means for cooling by contacting an inner surface of the belt.

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