JP2007057775A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a fixing device that can prevent a blister from being formed and has no level difference in luster due to a temperature difference of a fixing member. <P>SOLUTION: In the image forming apparatus having the fixing device constituted so that a toner image formed on an image formation body by an image formation part is transferred to an image support member and the unfixed toner image on the image support member is clamped and conveyed by a fixing member having a heating member and a pressing member to be heated and fixed, air outside the machine is guided to the fixing device to cool the fixing device and then the air is sent to one or both of image support member conveyance paths on upstream and downstream sides of a transfer part to preheat the image support member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, and a fax machine, and more particularly to an image forming apparatus having a fixing device using a heating member.

  2. Description of the Related Art Conventionally, a fixing device used in an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine having these functions includes a fixing roller as a fixing member maintained at a predetermined temperature, and an elastic layer. An image supporting member (hereinafter also referred to as paper or paper) on which an unfixed toner image is formed is sandwiched by a fixing nip formed by a pressing roller that is a pressing member that presses the fixing roller. 2. Description of the Related Art Heat roller fixing devices of a heat roller fixing system that pressurizes and heats while carrying are widely used from low speed machines to high speed machines, from monochrome machines to color machines.

  In recent years, a fixing belt as an endless fixing member is stretched between a heating roller and a fixing roller, and a pressing roller as a pressing member that presses the fixing roller via the fixing belt is provided, A belt fixing device for fixing a sheet by heating and pressing at a nip portion with a pressing roller has been proposed and used.

  In a color image forming apparatus in an electrophotographic system, digitization has progressed and high image quality has been achieved. In order to obtain high image quality, coated paper that has a smooth surface and is less likely to cause uneven gloss is often used as an image support member, such as coated paper or art paper coated with a coating layer on the surface.

  However, when heat-fixing by the above-described fixing device, water vapor evaporated inside the paper or expanded air may cause blisters that bulge the coating layer on the paper surface and cause irregularities. In particular, coated paper often used for color printing has poor air permeability and is liable to generate blisters. The blister tends to appear when the moisture content of the recording paper becomes high in a high humidity environment.

  As a countermeasure against the occurrence of blisters, a method is disclosed in which preheated coating paper is preliminarily heated to release moisture and air in the paper before fixing (for example, see Patent Document 1).

  Further, a method is disclosed in which cooling air around the fixing area is guided to a paper feed tray to preheat the transfer material (image support member) to increase the temperature and humidity of the transfer material (see, for example, Patent Document 2). .

  In addition to the blister, there is a problem due to temperature unevenness in fixing. The difference in gloss between the sheets is caused by a temperature difference in the fixing member depending on the presence or absence of the sheet when the sheet is passed, and this temperature difference occurs when the fixing member makes a round. In addition, when small-size paper is passed, overheating of the end portion where the paper of the fixing member does not pass causes hot offset and gloss unevenness.

In order to solve the above-described problem, a method is disclosed in which the overheating of the edge when the small-size paper is passed is cooled by blowing, by cooling the pressing member of the fixing device by blowing with a fan (for example, see Patent Documents 3 and 4) ).
Japanese Patent Laid-Open No. 9-325631 JP-A-6-202425 JP-A-5-107983 JP-A-4-51179

  As a countermeasure against the blister, in Patent Document 1, the preheating means is provided with a heater, so that the internal temperature rises due to heat generated by fixing and preheating, and the toner is fused and solidified, or malfunction due to overheating occurs. Have a problem. In addition, the structure of the apparatus becomes complicated, which causes a cost increase.

  In Patent Document 2, it takes time to heat the inside of the transfer material stored in the paper feed tray, and there is a problem that the effect is weakened by the rear transfer material during continuous paper feeding.

  In Patent Documents 3 and 4, although effective against the unevenness in gloss between sheets, hot offset, and uneven gloss due to fixing temperature unevenness, it is not compatible with blisters, and it is necessary to cope with blisters separately. Becomes complicated and increases costs.

  The present invention has been made in view of the above situation, and with a simple configuration, it is possible to prevent gloss level difference, hot offset, and gloss unevenness between papers due to temperature unevenness of fixing, and also to prevent occurrence of blisters and reduce productivity. An object of the present invention is to provide an image forming apparatus capable of obtaining a high-quality image without using the image forming apparatus.

The above object is achieved by the following configuration.
(1) The toner image of the image forming body formed in the image forming unit is transferred to an image supporting member by a transfer unit, and the unfixed toner image on the image supporting member is nipped and conveyed by a fixing member having a heating member and a pressing member. In an image forming apparatus having a fixing device for heat fixing,
Blowing means for introducing air outside the machine, an air flow passage for introducing and blowing the introduced air to the fixing device, and an image of one or both of the upstream and downstream of the transfer unit for the air blown to the fixing device to cool the fixing device An image forming apparatus comprising: an air flow path that leads to a support member transport path; and a discharge unit that discharges air that has passed through the image support member transport path to the outside of the apparatus.
(2) The image forming apparatus according to (1), wherein air introduced from outside the apparatus is guided to a fixing device to cool the pressing member.
(3) Item (1) or (2) is characterized in that air introduced from outside the apparatus is guided to a fixing device, and one or both of the fixing member and the pressing member are cooled. The image forming apparatus described.
(4) The air whose temperature has been raised by the cooling is blown out to the conveying member of the image supporting member and the guide member of the image supporting member constituting the image supporting member conveying path, and the air is prevented from touching the image supporting member. The image forming apparatus according to any one of (1) to (3), wherein a flow path is formed.
(5) A heat insulating image supporting member conveying path surrounded by a heat insulating member is provided downstream of the paper feed tray, and an air flow passage is formed in the heat insulating image supporting member conveying path so that the air used for the cooling flows. The image forming apparatus according to any one of (1) to (4), wherein:
(6) The heat insulating member is provided between the periphery of the image forming portion excluding the transfer portion and the image supporting member conveyance path upstream of the fixing, according to any one of (1) to (5) Image forming apparatus.
(7) The air whose temperature has been raised by the cooling is blown to the conveying member and the guide member of the image support member downstream of the transfer unit, and the air is prevented from touching the image support member. The image forming apparatus according to any one of items (6) to (6).
(8) An air flow path for guiding the air used for the cooling to the image support member conveyance path and an air flow path for guiding the heat insulation image support member conveyance path surrounded by the heat insulation members outside the apparatus and downstream of the paper feed tray. And a switching means for switching between blowing and blocking air to the image supporting member conveying path and a temperature detecting means for the image supporting member conveying path upstream or downstream of the transfer section, and the temperature of the image forming section is a predetermined temperature. Any one of the items (1) to (7), wherein the switching means switches between blowing and blocking the image supporting member conveyance path according to the temperature detected by the temperature detecting means so as not to exceed the temperature. Image forming apparatus.

  According to the above configuration, air outside the apparatus is guided to the fixing device, the fixing device is cooled, and the air whose temperature has been increased by the cooling is guided to one or both of the image support member conveyance paths upstream and downstream of the transfer unit, By heating the image support member conveyance path and preheating the paper, moisture and air in the paper can be released before fixing, and blistering can be prevented. Also, by preheating the paper, it is possible to reduce the temperature drop of the fixing member when the paper is passed through the fixing device, and when the fixing member goes around due to a temperature difference in the fixing member with or without paper In addition, it is possible to reduce the occurrence of a gloss level difference between the papers due to this temperature difference.

  In the cooling of the fixing device, the pressure member is cooled by air guided to the fixing device, and the temperature-increased air is sent to at least one of the image supporting member conveyance paths upstream and downstream of the transfer unit, thereby fixing the pressure member by cooling. The temperature of the fixing member decreases because the member comes into contact with the pressing member whose temperature has dropped between the sheets, and the temperature of the sheet increases due to heating of the image supporting member conveyance path by the air whose temperature has increased, and the contact portion between the fixing member and the sheet The temperature difference becomes smaller. This further improves the gloss level difference between the sheets.

  In addition, by cooling the fixing member and the pressing member, or the image supporting member non-passing portion of the fixing member and the pressing member with the air guided to the fixing device, it is possible to prevent the end portion heating at the time of passing the small size paper, Gloss unevenness and hot offset due to temperature overheating of the image support member non-passing portion can be prevented. Furthermore, the paper can be preheated by sending the air whose temperature has been raised by the cooling to at least one of the image support member conveyance paths upstream and downstream of the transfer section.

  Further, a heat insulating image supporting member conveyance path surrounded by a heat insulating material is provided downstream of the paper feed tray away from the image forming unit, and the air is heated by cooling the fixing device and heating the paper through the air whose temperature has increased. Even if the temperature is high, the influence on the image forming portion can be reduced, and the dehumidifying effect of the paper by preheating can be enhanced.

  Hereinafter, the image forming unit is also referred to as an image forming unit.

  Embodiments of the image forming apparatus according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a conceptual diagram of an image forming apparatus according to the present invention. The image forming apparatus of the present invention is not limited to the following form.

  In FIG. 1, the image forming apparatus GS includes an image forming apparatus main body GH and an image reading apparatus YS.

  The image forming apparatus main body GH is called a tandem color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a belt-shaped intermediate transfer body 6 that is an image forming body, and a paper feed conveyance. And a fixing device 9 described later.

  An image reading device YS including an automatic document feeder 201 and a document image scanning exposure device 202 is installed on the upper part of the image forming apparatus main body GH. The document D placed on the document table of the automatic document feeder 201 is transported by a transport unit, and an image on one or both sides of the document is scanned and exposed by the optical system of the document image scanning exposure device 202, and the line image sensor CCD is scanned. Is read.

  The analog signal photoelectrically converted by the line image sensor CCD is subjected to processing such as analog processing, A / D conversion, shading correction, and image compression processing in the image processing unit, and once stored in the memory, the image writing unit (Exposure means) 3Y, 3M, 3C, 3K.

  An image forming unit 10Y that forms a yellow (Y) image includes a photosensitive drum 1Y as an image carrier, a charging unit 2Y, an exposure unit 3Y, a developing device 4Y, and a cleaning unit 8Y disposed around the photosensitive drum 1Y. An image forming unit 10M that forms a magenta (M) color image includes a photosensitive drum 1M as an image carrier, a charging unit 2M, an exposure unit 3M, a developing device 4M, and a cleaning unit 8M. An image forming unit 10C for forming a cyan (C) image includes a photosensitive drum 1C as an image carrier, a charging unit 2C, an exposure unit 3C, a developing device 4C, and a cleaning unit 8C. An image forming unit 10K that forms a black (K) image includes a photosensitive drum 1K as an image carrier, a charging unit 2K, an exposure unit 3K, a developing device 4K, and a cleaning unit 8K. The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure unit 3C, and the charging unit 2K and the exposure unit 3K constitute a latent image forming unit.

  Each of the developing devices 4Y, 4M, 4C, and 4K includes a two-component developer composed of a toner having a small particle diameter and a carrier of yellow (Y), magenta (M), cyan (C), and black (K). .

  The intermediate transfer body 6 is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred (primary transfer) and synthesized on the rotating intermediate transfer body 6 by the transfer units 7Y, 7M, 7C, and 7K. A color image is formed. The sheet P as a transfer material accommodated in the sheet feeding tray 20 is fed by the sheet feeding unit 21 and is conveyed to the transfer unit 7A through the sheet feeding rollers 22A, 22B, 22C, 22D, the registration roller 23, and the like. Then, a color image is transferred onto the paper P (secondary transfer). The paper P on which the color image has been transferred is sandwiched in a nip portion N (see FIG. 2; not shown in FIG. 1) formed in the fixing device 9, and heat and pressure are applied to the paper P on the paper P. The color toner image (or toner image) is fixed and fixed on the paper P, and is sandwiched between the paper discharge rollers 24 on the paper discharge path side and placed on the paper discharge tray 25 outside the apparatus.

  At the time of double-sided image formation, a color image (color toner image) is formed on one side (first side), and the paper P fixed by the fixing device 9 is branched from the sheet discharge path by the branching unit 26, respectively. After passing through the lower circulating paper passage 27A constituting the paper feed conveyance means, the front and back are reversed by the reverse conveyance path 27B which is a refeed mechanism (ADU mechanism), and passes through the refeed conveyance section 27C to be fed. The paper roller 22D joins the transport path of the paper P supplied from the paper feed tray 20.

  The sheet P that has been reversed (circulated and reversed) is conveyed again to the secondary transfer roller 7A through the registration roller 23, and a color image (color toner image) is formed on the other surface (second surface) of the sheet P. Batch transfer. The sheet P on which the color image has been transferred is subjected to fixing processing by the fixing device 9 and is sandwiched between the sheet discharge rollers 24 on the sheet discharge path side and placed on the sheet discharge tray 25 outside the apparatus.

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

  Reference numeral 300 denotes a control unit of the image forming apparatus GS, and 300A denotes an operation / display unit.

  Next, an example of an embodiment of the fixing device will be described with reference to FIG. FIG. 2 is a schematic sectional view of the fixing device 9.

  A fixing roller 91 as a fixing member incorporates a halogen lamp 91D as a heating means. For example, an outer peripheral surface of a cylindrical hollow rotating body 91C having a thickness of 3 to 5 mm formed of aluminum or the like is used as an elastic layer 91B. It is covered with heat-resistant silicon rubber (hardness JIS-A 5 to 20 °) having a thickness of 2 to 3 mm, and further covered with a PFA tube having a thickness of 30 to 70 μm as a surface layer 91A, thereby constituting a soft roller. The outer diameter is 55 mm, for example.

  Any heating means may be used as the heating means. For example, a heater or an induction heating heating element using an exciting coil may be used.

  The pressing roller 92 as a pressing member is formed of, for example, a heat-resistant silicon rubber (thickness 2 to 4 mm) having an outer peripheral surface of a cylindrical hollow rotating body 92C made of aluminum or the like having a thickness of 3 to 5 mm as an elastic layer 92B. The release layer 92A is covered with a PFA tube having a thickness of 30 to 70 μm. In addition, an outer diameter dimension is 50 mm, for example.

  In this embodiment, the heat roller fixing method is used, but the above-described belt fixing method may be used.

Next, cooling of the fixing device and preheating of the sheet according to the present invention will be described with reference to the drawings.
<Embodiment 1>
FIG. 1 shows an outline of Embodiment 1 in which air introduced from outside the apparatus is led to the fixing device and cooled, and the fixing device is cooled and the paper is preheated with air whose temperature has been increased. FIG. 3 is a partial view around the air flow path in the first embodiment shown in FIG.

  In the first embodiment, the air circulation path is a blower fan 101A that is a blowing means for introducing air outside the apparatus, a duct 102 that forms an air flow passage that guides the introduced air to the fixing device, and air that cools the fixing device. From the ducts 103, 104, and 105 that form air flow paths that lead the paper to the upstream and downstream sheet conveying paths, and from the insulated sheet conveying path 110 and duct 103 that are surrounded by a heat insulating member that is disposed downstream of the sheet feeding tray. It is composed of a duct 106 that forms an air flow path that branches and guides air to the heat-insulating paper conveyance path 110 and an exhaust fan 101C that is a discharge means for discharging the air out of the apparatus.

  As shown in FIGS. 1 and 3, the air introduced from the outside by the blower fan 101 </ b> A is sent to the fixing device 9 through the introduction duct 102. The air whose temperature has risen after cooling the fixing device 9 passes through the ducts 103, 104, and 105 and is sent to the paper conveyance path 221 downstream of the transfer unit and the paper conveyance path 222 upstream of the transfer unit.

  The air after cooling the fixing device is taken into the duct 103 to prevent the heat of the fixing device from being dissipated into the apparatus, and the rise in the internal temperature due to the heat of the fixing apparatus is reduced. In order to efficiently take the air that has cooled the fixing device into the duct 103, an auxiliary blower fan 101 </ b> B that blows air in the direction of the arrow indicating the flow of air may be provided in the middle of the duct 103.

  The air taken into the duct 103 passes through the ducts 104 and 105 and is blown to the sheet conveyance paths 221 and 222 upstream and downstream of the transfer unit to heat the sheet conveyance path and preheat the sheet. By preheating the paper, moisture and air in the paper can be released before fixing, and blistering can be prevented. Also, by preheating the paper, it is possible to reduce the temperature drop of the fixing member when the paper is passed through the fixing device, and when the fixing member goes around due to a temperature difference in the fixing member with or without paper In addition, it is possible to reduce the occurrence of a gloss level difference between the papers due to this temperature difference.

  FIG. 6 is a schematic view of a blow-out port from which air that has cooled the fixing device blows out to the sheet conveyance path via a duct, and shows an example of a blow-out port on the upstream side of the transfer unit. The paper transport guides 222A and 222B are paper guide members for transporting the paper P, and are installed with a predetermined interval. Air outlets 105 </ b> A and 105 </ b> B are air outlets connected to the duct 105. The configuration is the same on the downstream side of the transfer portion.

  In FIG. 6, the air blown out of the blowout ports 105A and 105B through the duct 105 is blown out and heated to the paper conveyance guides 222A and 222B and the registration roller 23 which is a conveyance member.

  The air blown out from the blowout ports 105A and 105B is formed so as not to directly hit the paper P.

  In the vicinity of the fixing outlet, water vapor is generated by heating the paper, and the air that has cooled the fixing device 9 is likely to contain the water vapor. However, as shown in FIG. Further, by blowing out to the paper transport guides 222A and 222B and forming an air flow path so that air does not contact the paper, an increase in the humidity of the paper can be prevented.

  Further, in the paper conveyance path 221 downstream of the transfer unit in which the toner image formed on the paper is unfixed, air is not brought into contact with the paper surface, but is blown to the paper conveyance member and the paper guide member. The paper can be preheated without scattering the toner image.

  The air branched from the duct 103 to the duct 106 is sent to the heat insulating paper conveyance path 110. Further, the paper P stored in the paper feed tray 20 is fed by the paper feed means 21 and sent to the heat insulating paper transport path 110 and further sent to the paper feed roller 22A. Even if the temperature of the air is high, an insulating paper conveyance path 110 is provided in the downstream of the paper feed tray away from the image forming unit, and the fixing device is cooled to blow the heated air to heat the paper. The influence on the image forming unit can be reduced, and the dehumidifying effect of the paper by preheating can be enhanced.

  The heat insulating material of the heat insulating paper conveyance path 110 is composed of, for example, glass wool (thermal conductivity 0.04 W / m · K), ceramic fiber (thermal conductivity 0.06 W / m · K), etc., and a thickness of 5 to 12 mm. Is done.

  The air that has passed through the paper transport paths 221 and 222 and the heat insulating paper transport path 110 is exhausted from the exhaust fan 101C to the outside of the apparatus. The exhaust means may be only an exhaust port without an exhaust fan.

  Further, in the image formation of the image forming unit, if the temperature of the image forming unit is about 60 ° C., the toner may be hardened and image formation may be difficult. On the other hand, by providing the heat insulating members 121 and 122 between the periphery of the image forming unit excluding the transfer unit and the sheet conveyance path upstream of the fixing, the fixing device is cooled and the heated air flows into the image forming unit. Can be prevented, and an increase in the temperature of the image forming portion is reduced.

  Further, in order to prevent an increase in the temperature of the image forming unit, the temperature detection means S1 is provided in the paper conveyance path 221 downstream or the upstream conveyance path 222, and the paper conveyance path 221 and the paper conveyance path 222 are provided in the duct 103. It is also possible to provide an air valve 101D which is a ventilation switching means for controlling the ventilation of the air and to control the ventilation to the paper transport paths 221 and 222 by the ventilation switching means 101D according to the temperature detected by the temperature detection means S1. Air blowing to and blocking from the sheet conveying path 221 and the sheet conveying path 222 is performed so that the temperature of the image forming unit does not exceed a predetermined temperature, 50 ° C.

  The air valve 101D is driven by driving means (not shown). In the present embodiment, the air valve 101D is provided at a position where the duct 106 branches from the duct 103.

  The air blocked by the air valve 101D to the paper conveyance path 221 and the paper conveyance path 222 is sent to the heat insulating paper conveyance path 110 through the duct 106 and exhausted from the exhaust fan 101C.

In the first embodiment, as described above, the fixing device is cooled by air introduced from outside the apparatus, and the air is sent to the paper conveyance path upstream of the transfer unit, the paper conveyance path downstream of the transfer unit, and the heat insulation paper conveyance path. Although the paper is preheated, it is possible to provide either one or both of the paper conveyance path upstream of the transfer unit and the paper conveyance path downstream of the transfer unit without providing the heat insulating paper conveyance path. Further, a heat insulating paper conveyance path may be provided and combined with either the paper conveyance path upstream of the transfer unit or the paper conveyance path downstream of the transfer unit.
<Embodiment 2>
FIG. 4 shows a second embodiment in which the pressure roller of the fixing device is cooled by air introduced from the outside of the apparatus, and the sheet conveyance path upstream and downstream of the transfer unit is heated by the air heated by the cooling to preheat the sheet. It is the schematic of the blowing outlet and suction inlet of the duct of a roller cooling part.

  Except for the mode of the blowout port and suction port of the duct of the pressure roller cooling portion shown in FIG.

  Air introduced from the outside of the machine passes through the duct 102 and is blown out from the outlet 102A to the pressing roller 92. The air that has cooled the pressure roller 92 is sent to the duct 103 via the suction port 103A.

Fixing because the air outside the machine is guided to the fixing device, the pressure roller is cooled, and the temperature-increased air is sent to the paper conveyance path upstream and downstream of the transfer unit, so that the fixing roller contacts the pressure roller whose temperature has dropped between the papers. The temperature of the roller decreases, and the temperature of the paper increases due to preheating, and the temperature difference between the contact portion between the fixing roller and the paper is reduced. This further improves the gloss level difference between the sheets.
<Embodiment 3>
FIG. 5 shows that the non-passage portion of one or both of the fixing roller and the pressure roller is cooled by air introduced from outside the machine, and the paper conveyance path downstream and upstream of the transfer portion is heated by the air heated by the cooling. FIG. 6 is a schematic view of a blowout port and a suction port of a duct of a pressure roller cooling part of Example 3 for preheating a sheet.

  Example 1 is the same as Example 1 except for the mode of the outlet and suction port of the duct of the pressure roller cooling portion shown in FIG.

  Air taken from outside the apparatus passes through the duct 102 and is blown out from the outlet 102B to the sheet non-passing portions of the fixing roller 91 and the pressing roller 92. The air that has cooled the fixing roller 91 and the pressure roller 92 is sent to the duct 103 via the suction port 103B.

  By guiding the air outside the machine to the fixing device and cooling the paper non-passing part of one or both of the fixing member and the pressing member, it is possible to prevent edge heating when passing small-size paper. Gloss unevenness and hot offset due to temperature overheating of the non-passing portion can be prevented. Further, the paper can be preheated by sending the air whose temperature has been increased by the cooling to the paper conveyance path on the upstream and downstream of the transfer portion.

1 is a schematic configuration diagram of an image forming apparatus according to the present invention. 1 is a schematic cross-sectional view of a fixing device according to the present invention. FIG. 2 is an enlarged view around the air flow passage of FIG. 1. It is the schematic of the air blowing outlet and suction inlet of a press roller cooling part. FIG. 6 is a schematic view of an air outlet port and a suction port for cooling a paper non-passage portion of a pressing roller and a fixing roller. FIG. 6 is a schematic view of a blow-out port that blows out air to a paper transport path.

Explanation of symbols

DESCRIPTION OF SYMBOLS 9 Fixing device 91 Fixing roller 92 Pressing roller 101 Blower fan 101B Auxiliary blower fan 101C Exhaust fan 101D Blower switching means 102 Introduction duct 102A Outlet 102B Outlet 103, 104, 105, 106 Duct 103A Inlet 103B Inlet 110 Insulating paper conveyance Path 221 Transfer section downstream sheet conveyance path 222 Transfer section upstream sheet conveyance path

Claims (8)

The toner image of the image forming body formed in the image forming unit is transferred to an image supporting member by a transfer unit, and the unfixed toner image on the image supporting member is sandwiched and conveyed by a fixing member having a heating member and a pressing member, and heated. In an image forming apparatus having a fixing device for fixing,
Blowing means for introducing air outside the machine, an air flow passage for introducing and blowing the introduced air to the fixing device, and an image of one or both of the upstream and downstream of the transfer unit for the air blown to the fixing device to cool the fixing device An image forming apparatus comprising: an air flow path that leads to a support member transport path; and a discharge unit that discharges air that has passed through the image support member transport path to the outside of the apparatus. The image forming apparatus according to claim 1, wherein air introduced from outside the apparatus is guided to a fixing device to cool the pressing member. 3. The image forming apparatus according to claim 1, wherein air introduced from outside the apparatus is guided to a fixing device to cool a non-passing portion of one or both of the fixing member and the pressing member. Air that has risen in temperature due to the cooling is blown out to the conveying member of the image supporting member and the guide member of the image supporting member constituting the image supporting member conveying path, and an air flow passage is provided so that the air does not touch the image supporting member. The image forming apparatus according to claim 1, wherein the image forming apparatus is formed. A heat insulating image supporting member conveyance path surrounded by a heat insulating member downstream of the paper feed tray, and forming an air flow passage so that the air used for cooling flows into the heat insulating image supporting member conveying path; The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The image forming apparatus according to claim 1, wherein a heat insulating member is provided between the periphery of the image forming unit excluding the transfer unit and the image supporting member conveyance path upstream of the fixing. 7. The apparatus according to claim 1, wherein the air whose temperature has been raised by the cooling is blown out to a conveying member and a guide member of an image support member downstream of the transfer unit, and the air is prevented from touching the image support member. The image forming apparatus according to claim 1. An air flow path for guiding the air used for the cooling to the image support member conveyance path, and an air flow path for guiding the heat insulation image support member conveyance path surrounded by the heat insulation members outside the apparatus and downstream of the paper feed tray; A switching unit that switches between blowing and blocking air to the image support member conveyance path and a temperature detection unit for the image support member conveyance path upstream or downstream of the transfer unit so that the temperature of the image forming unit does not exceed a predetermined temperature. The image forming apparatus according to claim 1, wherein the air blowing and blocking to the image support member conveyance path are switched by the switching unit according to the temperature detected by the temperature detecting unit.

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