JP2007065090A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing deterioration of a printed image and electrophotographic characteristics by cooling a sheet with a simpler structure as compared with a conventional case when performing reverse side printing after front side printing.
SOLUTION: On the downstream side of the fixing device 8 in the paper conveyance direction, a paper discharge conveyance path 12 in a substantially horizontal direction, conveyance rollers 15 and 15 disposed upstream and downstream of the paper discharge conveyance path 12, and paper discharge The first reverse conveyance path 13 is provided in a substantially horizontal direction on the upper side of the first reverse conveyance path 13, which is provided in an L shape downward from the middle part of the conveyance path 12, and performs switchback of the paper for backside printing. A second reverse conveyance path 14 for guiding the reversed paper to the paper feed conveyance path 11 again is disposed. A cooling roller 17 and a pressure roller 16 made of aluminum and in contact with each other are arranged below the joining portion of the first reverse conveyance path 13 and the second reverse conveyance path 14. It conveys between the cooling roller 17 and the pressure roller 16.
[Selection] Figure 1

Description

  The present invention relates to an image forming apparatus that has a double-sided printing function and cools a sheet after front side printing before back side printing.

  In an image forming apparatus that employs an electrophotographic system, a fixing device having a fixing roller for heat-fixing a toner image transferred onto a sheet is provided. When the image forming apparatus has a double-sided printing function, a toner image is transferred to a sheet by a developing device, and then the toner image transferred to the sheet is heated and fixed by a fixing device to perform surface printing. The front-side printed paper is transported to the reverse transport path to reverse the front and back, and then the toner image is transferred again to the back of the paper by the developing device, and then the toner image transferred to the paper is heated and fixed by the fixing device. Then, back side printing is performed and the sheet is discharged to a discharge tray.

  When printing on the back side of paper that has been printed on the front side, the temperature of the paper that has been heat-fixed by the fixing device at the time of front side printing is high. As a result, the toner melts around the device, and the developing device close to the paper transport path is heated, so the toner is fused in the developing device, and the photoreceptor and developer itself It had adverse effects such as deterioration of electrophotographic characteristics.

In view of this, a heat absorbing member is provided in a portion that does not come into contact with the paper and generates an endothermic effect by applying a voltage. Air cooled by the endothermic effect of the endothermic member is supplied to the inside of the cooling roller having a hollow structure, and cooled. There has been proposed an image forming apparatus that removes the heat of a sheet conveyed while contacting a roller (see Patent Document 1).
JP-A-1-266557

  However, in the image forming apparatus of Patent Document 1, it is necessary to provide a heat absorbing member, and the structure of the cooling unit that cools the sheet is complicated, and the cost of the product may be increased. With such a configuration, an image forming apparatus that can efficiently remove heat from a sheet has been desired.

  The present invention has been made in view of such circumstances, and has a contact surface that comes into contact with a sheet, and includes a cooling unit that cools the sheet after heat-fixing on the front side. An object of the present invention is to provide an image forming apparatus capable of cooling a sheet with a simpler structure and preventing deterioration of printed image and electrophotographic characteristics.

  Another object of the present invention is to cool a sheet with a simpler configuration than the conventional one by providing a cooling unit that contacts the sheet with the outer peripheral surface of the metal cylinder. An object of the present invention is to provide an image forming apparatus capable of performing the above.

  Another object of the present invention is to provide a cooling section having an endless belt that contacts the paper and a rotating roller that is driven by stretching the endless belt, thereby increasing the contact surface with the paper, It is another object of the present invention to provide an image forming apparatus that can efficiently cool a sheet.

  Another object of the present invention is to provide an image forming apparatus that can more efficiently remove the heat of the paper by providing a pressure roller that presses the paper into contact with the contact surface of the cooling unit. It is in.

  Another object of the present invention is to provide the cylinder in the vicinity of one end or both ends of the cylindrical body, in the vicinity of one or both edges of the endless belt, or in the vicinity of one end or both ends of the pressure roller. An object of the present invention is to provide an image forming apparatus capable of removing heat of a sheet more efficiently by providing a blower for blowing air inside a body, an endless belt or a pressure roller.

  Another object of the present invention is to provide an image forming apparatus capable of improving toner releasability and preventing toner fusion by providing a fluororesin layer on the contact surface of the cooling section. It is to provide.

  Another object of the present invention is to quickly remove the heat of the paper heated by the fixing device by disposing the cooling unit in the path for reversing and conveying the paper and in the vicinity of the fixing unit. It is an object of the present invention to provide an image forming apparatus capable of doing so.

  Another object of the present invention is to provide an image forming apparatus that can reliably remove the heat of a sheet before printing on the back side by providing a plurality of cooling units in a path for reversing and conveying the sheet. There is to do.

  An image forming apparatus according to the present invention includes a fixing unit that heat-fixes a toner image transferred to a sheet for image formation, reversely conveys the sheet heat-fixed for image formation on the front side, and the back side of the sheet In the image forming apparatus for forming an image, the image forming apparatus includes a cooling unit that has a contact surface in contact with the sheet and cools the sheet after the front side heat fixing.

  The image forming apparatus according to the present invention is characterized in that the cooling section is a metal cylinder, and a sheet is brought into contact with the outer peripheral surface of the cylinder.

  The image forming apparatus according to the present invention is characterized in that a blower that blows air to the inside of the cylindrical body is provided near one end or both ends of the cylindrical body.

  The image forming apparatus according to the present invention is characterized in that the cooling unit includes an endless belt that contacts the sheet and a rotating roller that stretches and drives the endless belt.

  The image forming apparatus according to the present invention includes a blower that blows air to the inside of the endless belt at one edge or in the vicinity of both edges of the endless belt.

  The image forming apparatus according to the present invention includes a pressure roller that presses and contacts a sheet to a contact surface of the cooling unit, and the pressure roller is in contact with the contact surface.

  The image forming apparatus according to the present invention is characterized in that the pressure roller is a cylindrical body, and is provided with an air blowing section that blows air to the inside of the pressure roller near one end or both ends of the pressure roller. To do.

  The image forming apparatus according to the present invention is characterized in that the contact surface of the cooling section is provided with a fluororesin layer.

  The image forming apparatus according to the present invention is characterized in that the cooling unit is a path for reversing and conveying the sheet, and is disposed in the vicinity of the fixing unit.

  The image forming apparatus according to the present invention is characterized in that a plurality of the cooling units are provided in a path for reversing and conveying the sheet.

  In the present invention, the cooling unit has a contact surface that comes into contact with the paper, and dissipates heat of the paper that has become hot due to heat-fixing when forming an image on the front side of the paper by heat conduction through the contact surface Then, before the back side printing (image formation on the back side of the paper), the heat of the paper after the front side heat fixing is removed.

  In the present invention, the cooling part is a cylindrical body made of metal (for example, aluminum). By bringing the paper into contact with the outer peripheral surface of the cylindrical shape, the heat of the paper, which has become high due to heat-fixing when the paper is printed on the surface, is dissipated by heat conduction through the metal cylinder, and the surface printing (paper The heat of the paper after the image formation on the front side is removed.

  In the present invention, the blower blows air from the one end portion or the vicinity of both end portions of the cylindrical body to the inside of the cylindrical body. The blown air radiates heat conducted from the paper to the cylindrical body from the inside of the cylindrical body.

  In the present invention, an endless belt (for example, a belt) is driven by a rotating roller. When the belt is driven by heat-fixing during surface printing, the heat of the paper is driven by the belt contacting the paper to dissipate heat through the entire surface of the belt, and the heat of the paper after surface printing is dissipated. Remove.

  In the present invention, the air blower blows air from one edge or the vicinity of both edges inside the endless belt (for example, belt). The blown air radiates heat conducted from the paper to the belt from the inside of the belt.

  In the present invention, the pressure roller brings the paper into pressure contact with the contact surface of the cooling unit, and improves heat conduction from the paper to the cooling unit.

  In the present invention, the blower blows air from the one end of the pressure roller or the vicinity of both ends inside the pressure roller. The blown air radiates heat conducted from the paper to the pressure roller from the inside of the pressure roller.

  In the present invention, the contact surface of the cooling part is provided with a fluororesin layer.

  In the present invention, the cooling unit is a path for reversing and conveying the paper, and is disposed in the vicinity of the fixing unit. When the front side of the paper is printed, the heat of the paper that has passed through the fixing unit and has become high temperature is quickly cooled by the cooling unit.

  In the present invention, a plurality of the cooling units are provided in a path for reversing and conveying the paper. The heat of the paper, which has become a high temperature due to heat-fixing when the paper is printed on the front side, is repeatedly cooled by the cooling unit before the back side printing is performed.

  In the present invention, the heat of the sheet heated to the high temperature by the heat fixing at the time of surface printing is provided by providing the cooling unit that has the contact surface that contacts the sheet and cools the sheet after the front side heat fixing. Can be removed by heat conduction through the contact surface to remove the heat of the paper before the back side printing is performed. Deterioration of photographic characteristics can be prevented.

  In the present invention, by providing the cooling unit that contacts the sheet to the outer peripheral surface of the metal cylindrical body, the heat of the sheet heated to the high temperature by the heat fixing when the sheet is printed on the surface is made of the metal The heat of the paper can be removed by heat conduction through the cylindrical body, and the paper can be cooled with a simpler structure than in the past.

  In the present invention, by providing a blower that blows air to the inside of the cylindrical body near one end or both ends of the cylindrical body, heat conducted from the paper to the cylindrical body is released from the inside of the cylindrical body. And the heat of the paper can be removed more efficiently.

  In the present invention, the fixing unit includes a cooling unit having an endless belt (for example, a belt) that contacts the paper and a rotation roller that is driven by stretching the belt, thereby heating and fixing the paper on the surface. When the belt is driven in contact with the paper and driven by the belt, the entire surface of the belt comes into contact with the paper to increase the contact surface with the paper and dissipates heat by heat conduction through the entire belt. Further, the sheet can be cooled efficiently.

  In the present invention, a belt that blows air to the inside of the belt is provided at one edge or in the vicinity of both edges of the endless belt (for example, belt), so that the heat conducted from the paper to the belt is transmitted to the belt. The heat from the paper can be removed more efficiently.

  In the present invention, the heat transfer from the paper to the cooling unit is improved and the heat of the paper is more efficiently removed by providing a pressure roller that presses the paper against the contact surface of the cooling unit. Can do.

  In the present invention, the pressure roller is configured to include a blower that blows air to the inside of the pressure roller near one end or both ends of the pressure roller. The heat from the paper can be removed more efficiently.

  In the present invention, the contact surface of the cooling section is provided with a fluororesin layer, so that the toner releasability can be improved and toner fusion can be prevented.

  In the present invention, the cooling unit is a path for reversing and conveying the paper, and is disposed in the vicinity of the fixing unit, so that when the paper is printed on the front surface, the cooling unit passes through the fixing unit and becomes high temperature. The heat of the sheet can be quickly removed immediately after being heated by the fixing unit.

  In the present invention, by providing a plurality of cooling units in the path for reversing and conveying the paper, heat can be repeatedly removed from the paper, and the heat of the paper can be reliably removed before the back side printing is performed. .

Embodiment 1
Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments. FIG. 1 is a schematic front view of an image forming apparatus according to the present invention. In the figure, reference numeral 1 denotes a placing table on which a document is placed. Below the mounting table 1 are a light source 2 for irradiating a document with laser light, mirrors 3a, 3b, 3c for guiding the laser light irradiated from the light source 2 and reflected by the document to the photosensitive drum 4. A writing optical system including 3e, a lens 3d, and the like is disposed.

  A photosensitive drum 4 whose surface is coated with a photoconductive material is rotatably disposed at a substantially central portion of the image forming apparatus. Around the photosensitive drum 4, a charging charger 5, a developing device 6 having a developing roller 6 a that rotates in contact with the photosensitive drum 4, and a cleaning that rotates in contact with the photosensitive drum 4 along the rotation direction. A cleaning device 7 having a roller 7a is arranged. The charging charger 5 uniformly charges a single polarity charge on the surface of the photosensitive drum 4.

  An electrostatic latent image is formed on the surface of the photoreceptor 1 between the charging charger 5 and the developing device 6 by a photoconductive action caused by the irradiation of the laser light L from the writing optical system. The developing device 6 supplies toner to the surface of the photosensitive drum 4 on which the electrostatic latent image is formed, and visualizes the electrostatic latent image into a developer image.

  A transfer charger 9 for applying a transfer bias for transferring the developer image onto the sheet is disposed near the contact position where the sheet contacts the photosensitive drum 4.

  The paper stored in the storage unit 10 is sent out from the storage unit 10 by a paper supply roller (not shown), temporarily stopped by the registration rollers 23 and 23 via the paper supply conveyance path 11, and then the photosensitive drum 4. The image is sent to the photosensitive drum 4 in synchronism with the image formation. The developer image (toner image) is transferred to the sheet by corona discharge of the transfer charger 9 at the contact position with the photosensitive drum 4.

  The sheet on which the toner image is transferred is conveyed to a fixing device 8 having fixing rollers 8a and 8b. The fixing device 8 fixes the toner onto the paper by pressing the conveyed paper at high temperature with the fixing rollers 8a and 8b. Thereby, printing is performed on one surface (front surface) of the paper.

  On the downstream side of the fixing device 8 in the paper conveyance direction, the paper discharge conveyance path 12 is arranged in a substantially horizontal direction, the conveyance rollers 15 and 15 disposed upstream and downstream of the paper discharge conveyance path 12, and the paper discharge conveyance path 12. A first reversing conveyance path 13 that is provided in an L-shape downward from the midway part and that performs switchback of the paper for backside printing, is provided in a substantially horizontal direction above the first reversing conveyance path 13, A second reverse conveyance path 14 and the like for guiding the sheet to the sheet conveyance path 11 again are arranged.

  A conveyance switching guide 18 a for switching whether the sheet is conveyed to the paper discharge conveyance path 12 or the first reverse conveyance path 13 is disposed at the junction of the paper discharge conveyance path 12 and the first reverse conveyance path 13. Further, conveyance switching guides 18b and 18c for switching whether the sheet is conveyed to the paper discharge conveyance path 12 or the second reversal conveyance path 14 are provided at a junction of the first reverse conveyance path 13 and the second reverse conveyance path 14. It is arranged.

  Further, a plurality of transport rollers 15, 15,... For transporting paper are disposed in the middle of the first reverse transport path 13 and the second reverse transport path 14. A cooling roller 17 and a pressure roller 16 made of aluminum and in contact with each other are arranged below the joining portion of the first reverse conveyance path 13 and the second reverse conveyance path 14. It conveys between the cooling roller 17 and the pressure roller 16.

  The pressure roller 16 is brought into contact with the cooling roller 17 in a state where a predetermined pressure is applied by an urging means (not shown) such as a spring or a spring. The outer peripheral surfaces of the pressure roller 16 and the cooling roller 17 are coated with a fluororesin such as tetrafluoroethylene resin or polytetrafluoroethylene in order to prevent adhesion and toner fusion.

  FIG. 2 is a schematic side view of the image forming apparatus according to the present invention. In the figure, only the vicinity of the pressure roller 16 and the cooling roller 17 is illustrated. As shown in the figure, a fan 21a is disposed on the back side (rear side) of the image forming apparatus near both ends of the pressure roller 16 and the cooling roller 17, and the fan 21b is disposed on the front side (front side) of the image forming apparatus. It is arranged. An exhaust slit 22a for exhausting air and an intake slit 22b for intake are provided on the rear side and the front side of the image forming apparatus.

  By rotating the fans 21a and 21b, air flows in the direction of the arrow in the figure. The fan 21 b sends the outside air that has entered through the intake slit 22 b to the inside of the pressure roller 16 and the cooling roller 17. The fan 21a exhausts air inside the pressure roller 16 and the cooling roller 17 to the outside through the exhaust slit 22a. That is, the fans 21 a and 21 b blow so that air flows inside the pressure roller 16 and the cooling roller 17. As a result, outside air always flows inside the pressure roller 16 and the cooling roller 17, and the heat transferred from the paper to the cooling roller 17 by heat conduction is radiated from the inside of the cooling roller 17, and the cooling roller 17 Heat can be removed efficiently. Further, since the sheet is pressed against the cooling roller 17 by the pressure roller 16, the heat conduction efficiency can be further improved. Note that a configuration using only one of the fans 21a and 21b may be used.

  Next, the operation of the image forming apparatus according to the present invention will be described. For example, when double-sided printing (or double-sided copying) of a document is started by operating an operation switch provided on an operation panel (not shown) of the image forming apparatus, the paper stored in the storage unit 10 is fed. It is sent out from the storage unit 10 by a roller (not shown), temporarily stopped by the registration rollers 23 and 23 via the paper feeding / conveying path 11, and then the photosensitive drum in synchronism with the image formation on the photosensitive drum 4. 4 is sent. The developer image (toner image) is transferred to the sheet by corona discharge of the transfer charger 9 at the contact position with the photosensitive drum 4.

  The sheet on which the toner image is transferred is conveyed to the fixing device 8. The fixing device 8 fixes the toner onto the paper by pressing the conveyed paper at high temperature with the fixing rollers 8a and 8b. Thereby, printing is performed on one surface (front surface) of the paper.

  The sheet on which the toner is fixed is conveyed to the first reverse conveyance path 13 for switching back the sheet according to the guides of the conveyance switching guides 18a and 18b. The sheet conveyed between the cooling roller 17 and the pressure roller 16 during the conveyance is cooled by the cooling roller 17.

  The sheet conveyed to the first reverse conveyance path 13 is conveyed to the second reverse conveyance path 14 according to the guides of the conveyance switching guides 18b and 18c. The cooling roller 17 and the pressure roller 16 are disposed below the junction of the first reverse conveyance path 13 and the second reverse conveyance path 14 (between the first reverse conveyance path 13 and the second reverse conveyance path 14). Therefore, the sheet is cooled again by the cooling roller 17 while being conveyed to the second reverse conveying path 14. That is, when the paper after the front surface printing is printed on the back surface, the paper can be transported twice between the pressure roller 16 and the cooling roller 17, and the heat of the paper can be efficiently removed.

  The sheet transported to the second reversal transport path 14 is turned upside down, transported again to the paper feed transport path 11, temporarily stopped by the registration rollers 23 and 23 via the paper feed transport path 11, and then the photosensitive member. It is sent to the photosensitive drum 4 in synchronism with the image formation on the drum 4. The developer image (toner image) is transferred to the sheet by corona discharge of the transfer charger 9 at the contact position with the photosensitive drum 4.

  The sheet on which the toner image is transferred is conveyed to the fixing device 8. The fixing device 8 fixes the toner onto the paper by pressing the conveyed paper at high temperature with the fixing rollers 8a and 8b. Thereby, printing is performed on the other side (back side) of the sheet.

  The paper printed on both sides is discharged to a discharge tray (not shown) via the discharge transfer path 12 and the transfer roller 15 according to the guide of the transfer switching guide 18a.

  In the first embodiment, the aluminum cooling roller 17 is used. However, the present invention is not limited to this. The cooling pad is provided with a contact surface having a required area instead of the cooling roller 17. The structure using may be sufficient.

Embodiment 2
FIG. 3 is a schematic diagram showing an example in which the cooling pad 19 is used. The cooling pad 19 is a plate-shaped body made of aluminum, and the dimension in the longitudinal direction is substantially the same as the maximum width dimension of the paper. The surface of the cooling pad 19 that contacts the paper is coated with a fluororesin such as tetrafluoroethylene resin or polytetrafluoroethylene in order to prevent adhesion and toner fusion.

  The pressure roller 16 is brought into contact with the cooling pad 19 in a state where a predetermined pressure is applied by an urging means (not shown) such as a spring or a spring. The outer peripheral surface of the pressure roller 16 is coated with a fluororesin such as tetrafluoroethylene resin or polytetrafluoroethylene in order to prevent adhesion and toner fusion. Note that air may be sent to the inside of the pressure roller 16 as in the first embodiment.

  When the cooling pad 19 is used, the area where the paper comes into contact with the cooling pad 19 is larger than that of the cylindrical cooling roller. Therefore, the heat of the paper is removed with a simpler structure than when the cooling roller is used. can do. Note that the same portions as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the first embodiment described above, the aluminum cooling roller 17 is used. However, the present invention is not limited to this, and a configuration using a belt mechanism instead of the cooling roller 17 may be used.

Embodiment 3
FIG. 4 is a schematic diagram showing an example in which the belt mechanism 20 is used. The belt mechanism 20 includes two rotating rollers 20a and 20a, and a belt 20b (endless belt) that is stretched around the rotating rollers 20a and 20a and driven by the rotating rollers 20a and 20a. The pressure roller 16 is in contact with the belt 20b with a predetermined pressure applied by a biasing means (not shown) such as a spring or a spring. The outer peripheral surface of the pressure roller 16 is coated with a fluorine resin such as tetrafluoroethylene resin or polytetrafluoroethylene in order to prevent adhesion and toner fusion.

  The surface of the belt 20b that contacts the paper is coated with a fluororesin such as tetrafluoroethylene resin or polytetrafluoroethylene in order to prevent adhesion and toner fusion. Note that air may be sent to the inside of the pressure roller 16 as in the first embodiment. Moreover, you may make it send air into the inner side of the substantially circular part formed with the belt 20b.

  In the case where the belt mechanism 20 is used, the belt 20b can be brought into contact with the paper at a portion where the belt 20b is linearly stretched, and the area where the paper contacts the belt 20b is larger than that of the cylindrical cooling roller. Compared to the case of using a roller, the heat of the sheet can be removed with a simple configuration. Note that the same portions as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the first embodiment described above, one pressure roller 16 and the cooling roller 17 are provided. However, the present invention is not limited to this, and a plurality of pressure rollers 16 and the cooling roller 17 are provided. May be.

Embodiment 4
FIG. 5 is a schematic diagram showing an example in which a plurality of pressure rollers 16 and cooling rollers 17 are provided. In the first embodiment, in addition to the arranged pressure roller 16 and cooling roller 17 (upstream side), the pressure roller 16 and cooling roller 17 (downstream side) are arranged in the middle of the second reverse conveyance path 14. ing. In addition, the same code | symbol is attached | subjected to the location similar to Embodiment 1, and description is abbreviate | omitted.

  Thereby, when the back surface of the paper after the front surface printing is printed, the paper is transported twice between the pressure roller 16 and the cooling roller 17 on the upstream side and between the pressure roller 16 and the cooling roller 17 on the downstream side. Therefore, the heat of the sheet can be efficiently removed. Needless to say, air may be sent to the inside of the pressure roller 16 and the cooling roller 17 on the downstream side as in the first embodiment.

  In the above-described embodiment, the pressure roller 16 and the cooling roller 17 are provided on the downstream side, but the cooling pad 19 and the belt mechanism 20 may be provided instead of the cooling roller 17.

  In the above-described embodiment, the cooling unit such as the cooling roller 17, the cooling pad 19, and the belt mechanism 20 is located below the junction of the first reverse conveyance path 13 and the second reverse conveyance path 14 (first reverse conveyance). Between the path 13 and the second reversing conveyance path 14), but the position to be disposed is any path as long as the sheet is reversed and conveyed for reverse printing after front side printing. It may be the position. However, the vicinity of the downstream side of the fixing device 8 is preferable. Thereby, it is possible to quickly remove the heat of the sheet having a high temperature.

  In the above-described embodiment, the writing optical system for forming the electrostatic latent image on the photosensitive member 1 uses the reflected light from the document placed on the placing table 1, but is not limited thereto. In this configuration, an electrostatic latent image is formed on the photosensitive member 1 based on reflected light from a document read by an automatic document reader or data output from an information processing device such as a personal computer. It goes without saying.

  In the above-described embodiment, the fans 21a and 21b are provided in the vicinity of both ends of the cooling roller 17 and the pressure roller 16. However, the present invention is not limited to this, and the cooling roller 17 and the pressure roller 16 are not limited thereto. The structure provided in the one end part vicinity may be sufficient.

  In the above-described embodiment, the cooling roller 17 is configured to rotate freely around the rotation axis. However, the present invention is not limited to this, and a cylindrical rod body made of aluminum is fixedly disposed. Alternatively, the sheet may be conveyed in contact with the outer peripheral surface of the rod.

  In the above-described embodiment, the belt mechanism 20 has a configuration in which the two rotation rollers 20a are arranged in parallel to the rotation axis. However, the present invention is not limited to this, and one rotation roller 20a and one rod are provided. The body member may be arranged in parallel, the belt 20b may be stretched around the rotating roller 20a and the rod member, and the belt 20b may be driven by the rotating roller 20a.

  The image forming apparatus according to the present invention may form not only a monochrome image but also a color image, and may be not only a so-called multistage type but also a single type image forming apparatus.

1 is a schematic front view of an image forming apparatus according to the present invention. 1 is a schematic side view of an image forming apparatus according to the present invention. It is a schematic diagram which shows the example at the time of using a cooling pad. It is a schematic diagram which shows the example at the time of using a belt mechanism. It is a schematic diagram which shows the example at the time of providing a several pressurization roller and cooling roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 4 Photosensitive drum 5 Charger charger 6 Developing device 7 Cleaning device 8 Fixing device 10 Storage part 11 Paper feed conveyance path 12 Paper discharge conveyance path 13 1st reverse conveyance path 14 2nd reverse conveyance path 15 Conveyance roller 16 Pressure roller 17 Cooling Roller 19 Cooling pad 20 Belt mechanism 20a Rotating roller 20b Belt 21a, 21b Fan 22a Exhaust slit 22b Intake slit

Claims (10)

In an image forming apparatus that includes a fixing unit that heat-fixes a toner image transferred to a sheet for image formation, reversely conveys the sheet heat-fixed for image formation on the front side, and forms an image on the back side of the sheet.
An image forming apparatus comprising a cooling unit that has a contact surface that comes into contact with a sheet and that cools the sheet after front side heat fixing.   The image forming apparatus according to claim 1, wherein the cooling unit is a metal cylinder, and a sheet is brought into contact with an outer peripheral surface of the cylinder.   The image forming apparatus according to claim 2, further comprising an air blowing unit that blows air to the inside of the cylindrical body at one end portion or in the vicinity of both end portions of the cylindrical body.   The image forming apparatus according to claim 1, wherein the cooling unit includes an endless belt that contacts the sheet and a rotating roller that stretches and drives the endless belt.   The image forming apparatus according to claim 4, further comprising: a blower that blows air to the inside of the endless belt at one edge or in the vicinity of both edges of the endless belt.   6. The pressure roller according to claim 1, further comprising a pressure roller that press-contacts the sheet with a contact surface of the cooling unit, wherein the pressure roller is in contact with the contact surface. The image forming apparatus described.   The image forming apparatus according to claim 6, wherein the pressure roller is a cylindrical body, and includes an air blowing section that blows air to the inside of the pressure roller near one end portion or both end portions of the pressure roller. apparatus.   The image forming apparatus according to claim 1, wherein a contact surface of the cooling unit is provided with a fluororesin layer.   The image forming apparatus according to claim 1, wherein the cooling unit is a path that reversely conveys the sheet and is disposed in the vicinity of the fixing unit. The image forming apparatus according to claim 1, wherein a plurality of the cooling units are provided in a path for reversing and conveying the sheet.

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