JP4822341B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus for fixing a toner image formed on a transfer material, and more particularly, to a fixing unit for fixing a toner image on a transfer material from an image forming unit for forming the toner image on the transfer material. The present invention relates to an image forming apparatus including a conveying unit that conveys a material.

  Patent Documents 1 and 2 are configurations in which toner images of two or more colors are formed on a transfer material.

  In Patent Document 1, as shown in FIG. 1, a supply roll for supplying a web on which a color image is formed, a plurality of image print engines for forming a color image on the web, and a web are sent to the image print engine side. It comprises a pair of registration rollers and driving means for conveying the web on which the color image is formed in cooperation with the registration rollers to the next step.

  The plurality of image print engines are arranged in series along a predetermined convex curvature radius between the pair of registration rollers and the driving unit.

  Under this configuration, the web travels from the supply roll along one paper path and then passes through the drive means in close contact with the print engine photoreceptor drum after passing through a pair of register rollers. .

The web that has passed through the driving means is sent to a fusing device (fuser) where the next process is performed,
After the color image is fixed on the web, it is discharged from the output tray.

  Further, Patent Document 2 discloses a configuration in which a plurality of image forming units are arranged in a transfer path of a transfer material formed in a vertical direction.

  In this configuration, as shown in FIG. 2, four image forming units of yellow, magenta, cyan, and black are arranged in a vertical direction in a housing, and a paper feeding cassette that accommodates supply paper is arranged below the image forming units. It is installed. Further, a sheet conveyance path serving as a sheet conveyance path from the sheet feeding cassette is arranged in a vertical direction at a position corresponding to each image forming unit.

  With the configuration as described above, as shown in FIG. 4, in Patent Document 2, when the leading end of the paper in the paper feed cassette reaches the entrance-side nip transport roll, the paper is nip transported by the entrance-side nip transport roll. Then, the sheet sequentially enters the transfer portion of each image forming unit in the sheet conveyance path. During this time, the unfixed toner image is transferred to a predetermined position on the sheet.

In order to solve the above problems, the present invention provides an image forming unit that forms a toner image on a transfer material, a fixing unit that fixes the toner image formed on the transfer material, and the transfer material as an image forming unit and a fixing unit. In the image forming apparatus including the nipping and conveying unit, the conveying unit includes a first conveying unit that moves the transfer material to the image forming unit, and a transfer material conveyance direction after the toner image is formed on the transfer material. And a second conveying unit that moves the transfer material to the fixing unit by deviating, and the second conveying unit has a roller body rotatable in the conveying direction of the transfer material, and a toner image on the roller body via the transfer material. Charging means for applying a charge having the same polarity as the polarity of the toner, and the charging means includes a corona house having an opening facing the surface on which the toner image is formed on the transfer material, and a tension member in the corona house. Corona wire, and corona house The corona house is provided with air blowing means for blowing air onto the transfer material that has moved to the roller body. The transfer material is moved to the fixing unit side while preventing .

Japanese Patent No. 3351553 ([0015] to [0024], [FIG. 1]) Japanese Patent No. 30312250 ([0019] to [0030], [FIG. 1] and [FIG. 4])

  Here, in Patent Document 1, the transfer material is conveyed from the image forming unit to the fixing device in Patent Document 1 by a vacuum conveying mechanism provided downstream of the tandem print engine.

  This vacuum transport mechanism is composed of a drive roller and an idler roller that are driven while supporting an endless belt. Further, the endless belt has a large number of holes communicating with the vacuum source, and the endless belt rotates and holds the transfer material on the belt.

  However, this configuration has a large number of parts and high manufacturing costs. Further, since the transfer material is held by sucking air from a large number of holes communicating with the vacuum source, the suction force acts also from the hole on the side where the transfer material is not sucked, and the transfer material holding force becomes weak. As a result, it is necessary to slow down the rotation of the endless belt in order to maintain the holding force of the transfer material.

  Further, since the vacuum source for sucking the transfer material is performed by rotating the fan, a noise of rotation sound is generated. In addition, an auxiliary device for sucking from the fan must be provided, which increases the size of the device itself.

  Further, in the configuration of Patent Document 2, the transfer material is conveyed from the image forming unit to the fixing device, as shown in FIG. An arcuate guide surface toward the nip region of the fixing device is formed, and the transfer material is conveyed along the arcuate guide surface.

  For this reason, when a transfer material having weak properties such as a wide transfer material or tracing paper is transported to the fixing device, the leading end of the transfer material is inclined downward due to its own weight and is transported in a bent state.

In order to solve the above problems, the present invention provides an image forming unit that forms a toner image on a transfer material, a fixing unit that fixes the toner image formed on the transfer material, and the transfer material as an image forming unit and a fixing unit. In the image forming apparatus including the nipping and conveying unit, the conveying unit includes a first conveying unit that moves the transfer material to the image forming unit, and a transfer material conveyance direction after the toner image is formed on the transfer material. A second conveying means that shifts and transfers the transfer material to the fixing means,
The second conveying means includes a roller body that is rotatable in the conveying direction of the transfer material, and a charging means that applies a charge having the same polarity as the toner polarity of the toner image to the roller body via the transfer material. To do.

The invention described in claim 2 is characterized in that the applied voltage of the charging means is set to 5000V to 7500V.

According to a fourth aspect of the present invention, the distance between the fixing unit and the second conveying unit is set such that the amount of charge applied to the transfer material by the charging unit attenuates as the transfer material moves closer to the fixing unit, When the material moves to the vicinity of the fixing unit, it has a length that is substantially the same as the charge amount applied to the toner image formed on the transfer material.

According to a fifth aspect of the present invention, there is provided an image forming unit for forming a toner image on a transfer material, a fixing unit for fixing the toner image formed on the transfer material, and conveyance for nipping and conveying the transfer material between the image forming unit and the fixing unit. An image forming apparatus comprising:
The transport unit includes a first transport unit that moves the transfer material to the image forming unit, and a second transport unit that moves the transfer material to the fixing unit after the toner image is formed on the transfer material.
The second transport unit includes a rotatable roller body that deviates the transport direction of the transfer material, and a charging unit that applies an applied voltage having the same polarity as the polarity of the toner to the roller body via the transfer material,
The charging unit includes an opening facing the surface on which the toner image is formed on the transfer material, and a corona house formed along the curved portion of the roller body, and a corona wire stretched in the corona house Including
The corona house is provided with a blowing unit that blows air onto the transfer material that has moved to the roller body, and a guide roller that conveys the transfer material that has passed through the image forming unit to the fixing unit.
Further, the front end and the rear end of the corona house are provided with guide rollers in the longitudinal direction for preventing the entry into the corona house and conveying the transfer material that has passed through the image forming unit to the fixing unit.
The distance between the fixing unit and the second conveying unit is such that when the transfer material moves closer to the fixing unit, the amount of charge applied to the transfer material by the charging unit attenuates and the transfer material moves closer to the fixing unit. A length that is substantially the same as the amount of charge applied to the toner image formed on the transfer material ;
The charging means and the air blowing means move the transfer material to the fixing means side while preventing the transfer material from floating or jumping up .

  With the above configuration, according to the present invention, the conveying unit includes the first conveying unit that moves the transfer material to the image forming unit, and the second conveying unit that moves the transfer material to the fixing unit after the toner image is formed on the transfer material. A transfer means, and forming the second transfer means so as to deviate the transfer direction of the transfer material, thereby transferring a transfer material having a weak property such as a wide transfer material or tracing paper to the fixing device. It can be transported smoothly.

  Moreover, the effect mentioned above can be heightened by making the 2nd conveyance means into the member in which the curved part was formed, or making it into a roller body, and utilizing these curved surfaces.

  Further, the second conveying means comprises a roller body rotatable in the transfer material conveying direction and a charging means for applying a charge having the same polarity as the toner polarity of the toner image to the roller body via the transfer material, By setting the applied voltage of the charging unit to 5000 V to 7500 V, the transfer material can be conveyed while being held while preventing the transfer material from lifting or jumping.

As a specific example, the charging unit includes a corona house having an opening facing a surface on which a toner image is formed on a transfer material, and a corona wire stretched in the corona house. The above-mentioned effect can be obtained by forming so as to follow. Also,
By providing the corona house with a blowing means for blowing wind on the transfer material moved to the roller body, the above effect can be further obtained.

  In addition, by providing guide rollers in the longitudinal direction at the front and rear ends of the corona house, the transfer material is prevented from entering the corona house, and the transfer material that has passed through the image forming section is smoothly conveyed to the fixing means. can do.

  As the transfer material moves closer to the fixing device, the amount of charge applied to the transfer material by the charging device attenuates, and the transfer material moves closer to the fixing device. In some cases, the length is approximately the same as the amount of charge applied to the toner image formed on the transfer material, so that the unfixed toner image formed on the transfer material can be conveyed to the fixing unit without being disturbed. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 schematically shows an image forming apparatus according to the present invention.

  As shown in FIG. 1, in this image forming apparatus, a transport path is formed in a substantially vertical direction by two or more transport units 300, and two or more image forming units 100 are provided at a predetermined interval between the transport paths. Are arranged. Under this configuration, the transfer material P is fed from a paper feeding means (not shown) to the conveyance path, and a toner image is sequentially transferred to the transfer material P to form a color image, and then these unfixed color images are The fixing is performed by the fixing means 200 arranged at a predetermined position.

  The transfer material P is a sheet cut in advance at a predetermined timing by feeding a cut paper or roll paper cut to a specified size in advance for a certain period.

  The image forming unit 100 has a configuration in which yellow Y, magenta M, cyan C, and black BK are sequentially arranged.

  The image forming unit 100 includes an image carrier 110 and a transfer unit 120. For example, the image carrier 110 rotates in a direction indicated by an arrow, that is, in a counterclockwise direction, and has a configuration in which an electrophotosensitive member is provided on the surface of a drum-like substrate such as aluminum. As the photoconductor, a known photoconductor such as an OPC (organic photoconductor) photoconductor or an amorphous silicon photoconductor can be used.

  The image carrier 110 is configured to transfer the transfer material P from a line portion where the transfer material P connects the charged portion with the registration roller of the second conveyance unit 500 from the contact portion between the registration roller 410 and the counter roller 420 of the first conveyance unit 400 described later. It is arranged on the 120 side.

  With this arrangement, when the transfer material P passes through the image carrier 110, it contacts the image carrier 110 with a predetermined nip width, thereby preventing transfer leakage. The nip width is determined by the outer diameter and hardness of the image carrier 110.

  Around the image carrier 110, there are an eraser 140 for erasing residual charges on the image carrier 110, a charger 150 for uniformly charging the surface of the image carrier 110 to a specific polarity, and a charged image. An exposure device 160 for forming an electrostatic latent image on the surface of the image carrier 110 by making optical information incident (image exposure) on the surface of the carrier 110, and supplying a developer to the surface of the image carrier 110 for electrostatic A developing device 130 for developing the latent image to form a developer image and a transfer means 120 for transferring the developer image formed on the image carrier 110 to the transfer material P are arranged.

  Here, the developing device 130 includes a developing container 131 that contains a developer made of non-magnetic one-component toner, a stirring unit 132 that stirs the developer in the developing container 131, and at least the surface layer has conductivity. A developer carrier 133 made of an elastic roller, and a layer thickness regulating means 134 that is disposed in contact with the developer carrier 133 at an appropriate pressure and forms a thin layer of a constant developer on the developer carrier 133; And a developer supply means 135 for supplying the developer in the developer container 131 to the developer carrier 133.

  These are connected to an appropriate bias power source, and a predetermined bias voltage (bias) is applied to each of them. As the developer, for example, a developer having the same polarity as the charged polarity of the image carrier 110 is used for reversal development.

  The transfer unit 120 includes a corona transfer device 121 and a peeling device 122. The corona transfer device 121 includes a corona wire 123 and a corona house 124 that covers the corona wire 123. An appropriate number of corona wires 123 are stretched inside the corona house 124, one in the example of FIG. 1, and the corona wires 123 and the corona house 124 extend in the axial direction of the image carrier 110.

  When an image is formed on the transfer material P, first, in the state where the first image carrier 110 is rotating in the direction of the arrow, the residual potential remaining on the image carrier 110 is removed from the eraser 140, and the charger 150 uniformly charges the surface of the image carrier 110. The electrostatic latent image is conveyed to a position (developing section) in contact with the developer carrier 133 by the rotation of the first image carrier 110.

  On the other hand, in the developing device 130, in synchronization with the rotation of the image carrier 110, the developer carrier 133 and the developer supply means 135 are rotated in the directions indicated by the arrows by drive sources (not shown), and the developer carrier A predetermined bias voltage is applied to each of the body 133, the developer supply unit 135, and the layer thickness regulating unit 134.

  The developer in the developer container 131 is agitated by the rotation of the agitation means 132 and the developer supply means 135 and is supplied to the developer supply means 135 and then to the developer carrier 133 so that the developer layer is formed on the developer carrier 133. Is formed.

  The developer layer is regulated by the layer thickness regulating means 134 so as to be a uniform thin layer of 1 to 3, and then is carried to the development section as the developer carrier 133 rotates. The thinned developer is supplied to the electrostatic latent image on the image carrier 110 in the development section, and development is performed by suction and adsorption.

  The developer image formed on the first image carrier 110 is conveyed to the transfer area (nip width) by the rotation of the image carrier 110. Here, due to the action of the transfer means 120, an electric field having a polarity opposite to the polarity of the developer is applied from the back side of the transfer material P, and the toner image is transferred to the transfer material P.

  The toner images transferred by the first image forming unit 100 are sequentially transferred by the second image forming unit 100, the third image forming unit 100, and the fourth image forming unit 100, and the color image is transferred to the transfer material P. It is formed. Thereafter, the transfer material P on which the color image is formed is conveyed to the fixing unit 200 and fixed.

On the other hand, the developer remaining on the image carrier 110 that is not transferred to the transfer material P is exposed to the entire surface by the eraser 140 and becomes substantially the same potential as the dark portion potential (image background portion potential) of the image carrier 110.

  Subsequently, the same charging and exposure for image formation as described above are performed, and the developer is carried again to the developer carrier 133. The developer carrier 133 collects the developer remaining on the image carrier 110 to the developing device 130 and supplies a new developer to the surface of the image carrier 110 to generate the next electrostatic latent image. develop.

  Between each image forming unit 100, there is provided a suction conveyance unit 800 that first transfers the toner image and conveys the transfer material P to the next image forming unit 100. The suction conveyance unit 800 includes a conveyance belt 810 provided with a plurality of intake holes (not shown), and a roller 820 that supports the conveyance belt 810. Further, the suction conveyance unit 800 includes a flat portion 830 facing the surface opposite to the transfer surface of the toner image of the transfer material P, and the transfer unit excluding the transfer unit 120 that transfers the unfixed toner image of the first image forming unit. 120 and unitized.

  The fixing unit 200 includes a fixing roller 210 and a pressure roller 220. The fixing roller 210 has a good thermal conductivity. For example, an outer layer of an aluminum cylindrical tube is coated with an elastic layer such as silicon rubber to a thickness of about 0.8 to 10 mm, and a Teflon coating is formed on the surface. Yes.

  Further, a release agent supply means 230 is provided at an appropriate position of the fixing roller 210 to remove residues such as toner adhering to the surface of the fixing roller 210 and to apply a release agent to the surface of the fixing roller 210. The release agent supply means 230 includes a web 231 that is brought into contact with the circumferential surface of the fixing roller 210, a feed roller 232 that feeds the web 231 along the fixing roller 210, and a winding that winds the web 231 fed by the feed roller. The roller 233 includes a pressing unit 234 that presses the web 231 against the surface of the fixing roller 210.

  The transport unit 300 transports the transfer material P, and includes a first transport unit 400 and a second transport unit 500. The first conveying unit 400 is disposed in front of the image forming unit 100 that first transfers an unfixed toner image to the transfer material P. The second transport unit 500 is disposed after the image forming unit 100 that finally transfers the unfixed toner image to the transfer material P.

  Here, the gripping force of the first conveying means 400 is F1, and an image is formed on the transfer material P so as to be pulled from the image forming unit 100 that first transfers the unfixed toner image onto the transfer material P. When the grip force F2 of the image forming unit 100 (including the suction force of the suction conveyance unit 800) and the grip force of the second conveyance unit 500 are F3, the relationship of F1> n × F2 + F3 (n ≧ 2) is established. Is configured to do.

  The first transport unit 400 includes a registration roller 410 and a counter roller 420. The registration roller 410 is made of a material having small eccentricity, and the surface thereof is coated with a ceramic coat of about 25 μm in order to increase the coefficient of friction and increase the grip force of the transfer material P.

  The second transport unit 500 transports the transfer material P on which the unfixed toner image is transferred by each image forming unit 100 to the fixing unit 200. As shown in FIG. 2, the second transport unit 500 includes a member in which a curved portion C is formed, and deviates the transport direction of the transfer material P.

  Specifically, the second transport unit 500 applies a roller body 600 that is rotatable in the transport direction of the transfer material P, and a charge having the same polarity as the toner polarity of the toner image to the roller body 600 via the transfer material P. And charging means 700.

  The roller body 600 is the same as the registration roller 410 described in the first conveying unit 400. In this embodiment, the charging means 700 is a corona charger, and includes a corona wire 710 and a corona house 720 that covers the corona wire 710.

  In order to obtain a gripping force for holding the transfer material P, the corona wire 710 is stretched inside the corona house 720 by an appropriate number, three in the example of FIG. 2, and the corona wire 710 and the corona house 720 are The image carrier 110 extends in the axial direction.

  Further, the corona house 720 can provide the transfer material P with an electric field having the same polarity as that of the toner of the toner image, so that the opening 730 of the corona house 720 has substantially the same shape as the portion facing the roller body 600. It is formed to have a shape (along the curved portion C of the roller body 600). Specifically, the opening 730 of the corona house 720 is formed to have substantially the same curvature as that of the roller body 600 at a portion facing the roller body 600. In particular, when the diameter of the roller body 600 is 40 to 70 mm (preferably about 60 mm) and the length of the roller body 600 is 700 to 1000 mm (preferably 950 mm), the applied voltage of the charging means 700 is 5000 V to 7500 V (preferably 6500 V). By setting to the above, it is possible to simultaneously prevent the transfer material P from being lifted or bounced and to deviate the traveling direction of the transfer material P.

  Further, as shown in FIG. 3, the corona house 720 is provided with a blowing means 750. The air blowing means 750 blows wind onto the transfer material P moved to the roller body 600, so that not only the transfer material P having weak properties such as a wide transfer material P and tracing paper but also strong stiffness. Even if it is a thing, it can be smoothly conveyed to the fixing means 200. FIG.

  Further, guide rollers 740 (740a, 740b) are provided in the longitudinal direction at the front end and the rear end of the corona house 720. Accordingly, the transfer material P can be prevented from entering the corona house 720, and the transfer material P that has passed through the image forming unit 100 can be smoothly conveyed to the fixing unit 200.

  A guide member 900 that guides the transfer material P to a predetermined position of the fixing unit 200 is provided between the second conveying unit 500 and the fixing unit 200. The guide member 900 includes a first guide member 910 and a second guide member 920. The first guide member 910 is made of a plate-like member, and the tip is bent outward so that the tip of the transfer material P transported from the second transport unit 500 can be easily introduced.

  Further, the second guide member 920 is pivotally supported at one end side by a pivot, and is biased upward by a spring means (not shown) such as a coil spring. Also, detection means (not shown) such as a micro switch is provided below the second guide member 920, and detects the movement or pivoting of the second guide member 920 that occurs when the transfer material P passes. The control means (not shown) controls the peripheral speed of the fixing device based on the detection signal.

  Between the second conveying unit 500 and the fixing unit 200, as the transfer material P moves to the vicinity of the fixing unit 200, the amount of charge applied to the transfer material P by the charging unit 700 is attenuated, and the transfer material P When moved to the vicinity of the fixing unit 200, it has a length that is substantially the same as the amount of charge applied to the toner image formed on the transfer material P.

  Next, the operation of the image forming apparatus of the present invention will be described. First, when the leading edge of the transfer material P sequentially passes through each image forming unit 100 and is fed to the second conveying unit side, the transfer material P is moved along the curved portion C of the rotating roller body 600. The tip is guided.

  At this time, even if the leading edge of the transfer material P jumps upward and moves toward the charging means 700 due to winding or the like, the roller body 600 is in contact with the guide roller of the charging means 700 and the direction of the leading edge of the transfer material P is the roller body 600. Tilt to the side. Further, the tip of the transfer material P tilted toward the roller body 600 is urged toward the roller body 600 by the electrostatic force generated by the charging of the charging unit 700.

  As a result, even if the transfer material P jumps up and moves to the second transport unit 500, the tip of the transfer material P can be prevented from entering the charging unit 700.

  Even if the rear end of the transfer material P jumps or floats and moves to the roller body 600, the charging action of the guide roller and the charging unit 700 as described above, like the front end of the transfer material P, The rear end of the transfer material P is prevented from entering the charging unit 700.

  Further, the leading edge of the transfer material P passes through the fixing unit 200, and the transfer material P is being transported between the first transport unit 400 and the second transport unit 500 or between the suction transport unit 800 and the second transport unit 500. The transfer material P that has come into contact with the roller body 600 may be lifted by the winding of the transfer material P, the deformation of the transfer material P, the peripheral speed difference between the fixing roller 210 and the pressure roller 220, or the like.

  At this time, the portion of the transfer material P that is about to float up is in a state where the electrostatic force of the charging means 700 is pushed toward the roller body 600, that is, toward the roller body 600, and the transfer material P is prevented from being lifted up. Even if the rear end of the transfer material P passes through the charging unit 700 and jumps or rises, the rear end of the transfer material P comes into contact with the guide roller provided at the rear end of the charging unit 700. Is prevented from entering the charging means 700.

  Further, as the transfer material P moves to the vicinity of the fixing unit 200, the electric charge is gradually leaked through the transfer material P by the charging unit 700. When the charge amount applied to the material P is attenuated and the transfer material P moves to the vicinity of the fixing unit 200, the length is approximately the same as the charge amount applied to the toner image formed on the transfer material P. Thus, when the transfer material P onto which the toner image has been transferred moves between the fixing roller 210 and the pressure roller 220, the unfixed toner image formed on the transfer material P is not disturbed by the fixing means 200. Can be transported.

  As described above, the transfer material P is obtained by applying an electric field from the curved portion C, in particular, the curved portion C (curved surface) of the roller body 600 and the transfer surface of the unfixed toner of the transfer material P passing through the curved portion C. It is possible to simultaneously prevent the lifting and jumping of the sheet and to deviate the traveling direction of the transfer material P.

1 is a diagram showing an outline of an image forming apparatus of the present invention. The figure which shows the principal part of this invention. The figure which shows the principal part of other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image forming part 200 Fixing means 300 Conveying means 400 First conveying means 500 Second conveying means 600 Roller body 700 Charging means 740 Guide roller 750 Blower means C Curved part P Transfer material

Claims (5)

An image forming unit that forms a toner image on the transfer material; a fixing unit that fixes the toner image formed on the transfer material; and a conveyance unit that sandwiches and conveys the transfer material between the image forming unit and the fixing unit. In the image forming apparatus,
The transport unit includes a first transport unit that moves the transfer material to the image forming unit, and after a toner image is formed on the transfer material, the transfer material is displaced in the transport direction to deviate the transfer material. Second conveying means for moving to the fixing means,

The second conveying means, chromatic and rotatable roller member in the conveying direction of the transfer material, and a charging means for applying a polarity and charge of the same polarity of the toner of the toner image to the roller body through the transfer material And
The charging means includes a corona house having an opening facing a surface on which a toner image is formed on the transfer material, and a corona wire stretched in the corona house,
The corona house is formed along the curved portion of the roller body,
The corona house is provided with air blowing means for blowing air onto the transfer material moved to the roller body,
An image forming apparatus , wherein the transfer member is moved to the fixing unit side while preventing the transfer material from floating or jumping up by the charging unit and the blowing unit . 2. The image forming apparatus according to claim 1, wherein an applied voltage of the charging unit is set to 5000V to 7500V. At the front and rear ends of the corona house, guide rollers are provided in the longitudinal direction to prevent entry into the corona house and to convey the transfer material that has passed through the image forming unit to the fixing unit. the image forming apparatus請Motomeko 1 wherein Being. The distance between the fixing unit and the second conveying unit is such that as the transfer material moves closer to the fixing unit, the amount of charge applied to the transfer material by the charging unit is attenuated, and the transfer material is 3. The image forming apparatus according to claim 1 , wherein the image forming apparatus has a length that is substantially the same as an amount of charge applied to the toner image formed on the transfer material when moved to the vicinity of the fixing unit. An image forming unit that forms a toner image on the transfer material; a fixing unit that fixes the toner image formed on the transfer material; and a conveyance unit that sandwiches and conveys the transfer material between the image forming unit and the fixing unit. In the image forming apparatus,
The transport unit includes a first transport unit that moves the transfer material to the image forming unit, and a second transport unit that moves the transfer material to the fixing unit after a toner image is formed on the transfer material. Have
The second transport unit includes a rotatable roller body that deviates the transport direction of the transfer material, and a charging unit that applies an applied voltage having the same polarity as the toner to the roller body via the transfer material. And
The charging unit includes an opening facing the surface on which the toner image is formed on the transfer material, and a corona house formed along the curved portion of the roller body, and is stretched in the corona house. Corona wire and
The corona house is provided with a blowing unit that blows air onto the transfer material moved to the roller body, and a guide roller that conveys the transfer material that has passed through the image forming unit to the fixing unit.
Further, guide rollers for preventing the entry into the corona house in the longitudinal direction and conveying the transfer material that has passed through the image forming portion to the fixing unit are provided at the front and rear ends of the corona house. And
The distance between the fixing unit and the second conveying unit is such that as the transfer material moves closer to the fixing unit, the amount of charge applied to the transfer material by the charging unit is attenuated, and the transfer material is When moved to the vicinity of the fixing means, it has a length that is substantially the same as the charge amount applied to the toner image formed on the transfer material ,
An image forming apparatus , wherein the transfer member is moved to the fixing unit side while preventing the transfer material from floating or jumping up by the charging unit and the blowing unit .