JP2007065327A - Image forming apparatus and transfer fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transfer fixing device which includes a fixing rotation body having a means for heating an electrostatically formed toner image on a transfer fixing rotation body and a sheet-like medium conveying means forming a nip in pressure- contact with the transfer fixing rotation body and which is used to fix the toner image under pressure to the surface of the sheet-like medium passing through the nip between the transfer fixing rotation body and fixing rotation body, the transfer fixing device being designed so that the sheet-like medium subjected to transfer fixing is prevented from being wound around a transfer fixing member and is satisfactorily separated after fixing, and to provide an image forming apparatus. <P>SOLUTION: The transfer fixing device is provided with: a charging means 36 for electrostatically attracting a sheet-like medium to the fixing rotation body 31; and a discharging means 37 for separating the sheet-like medium from the fixing rotation body after transfer fixing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and a transfer fixing apparatus such as a copying machine, a printer, a facsimile, a plotter, and a multifunction machine.

  In an electrophotographic image forming apparatus, a high-viscosity and high-concentration liquid toner is used as a liquid developer, and a liquid developer is supplied in contact with an image support on which an electrostatic latent image is formed. An intermediate transfer body for transferring a toner image on the image support according to an electric field between the developing unit and the image support, and a toner image transferred to the intermediate transfer body, And a transfer fixing unit for melting and heating the printing medium and a medium conveying unit for conveying the printing medium to the transfer fixing unit, and the medium conveying unit applied a bias voltage. There is a liquid developing electrophotographic apparatus that conveys a print medium by adsorbing the medium with an electrostatic force on a medium conveyance belt formed of a seamless film having high heat resistance and high electrical resistance (see, for example, Patent Document 1).

  On the other hand, in the electrophotographic color image forming apparatus, the unfixed transfer paper passes through the fixing process while being electrostatically attracted to the transport belt, and then the fixed transfer paper is separated from the transport belt. There is a technique for preventing transfer paper from being wound around a fixing belt or the like (for example, see Patent Document 2).

  The former technique prevents the phenomenon that jam occurs because the print medium cannot be separated from the intermediate transfer medium due to the adhesive force of the toner in the transfer fixing unit by adsorbing and transporting the print medium to the electrostatic belt. In the latter technique, unfixed transfer paper is electrostatically adsorbed to the conveyance belt, but there is no guarantee that transfer paper after fixing is smoothly separated.

JP 2004-94112 A JP 2001-356613 A

In the transfer fixing apparatus as described above, since the recording medium is wound around the transfer fixing rotator after the toner having electrostatic attraction force and viscosity is transferred and fixed, the occurrence of a jam or the recording medium wrapped around the intermediate transfer body It deals with problems such as hurting, but it is not certain whether the subsequent separation will be performed smoothly.
SUMMARY OF THE INVENTION An object of the present invention is to provide a transfer fixing device and an image forming apparatus in which a transfer-fixed sheet-like medium does not wrap around a transfer fixing member and can be satisfactorily separated after fixing. .

In order to achieve the above object, according to the first aspect of the present invention, there is provided a means for heating an electrostatically formed toner image on a transfer fixing rotator, and forming a nip by pressing against the transfer fixing rotator. In a transfer fixing device including a fixing rotator that conveys a sheet-like medium so as to pass through the nip, the sheet-like medium is electrostatically attracted to the fixing rotator and conveyed, and is transferred from the transfer-fixing rotator at the nip portion. The toner image was transferred and fixed, and after the transfer and fixing, the charge applied to the electrostatic adsorption of the sheet-like medium to the fixing rotator was removed to separate the sheet-like medium from the fixing rotator.
According to a second aspect of the present invention, in the transfer fixing device according to the first aspect, the sheet-like medium is electrostatically attached to the fixing rotator at the upstream end in the sheet-like medium conveyance direction of the support means for supporting the fixing rotator. Of the charging means for statically adsorbing, and the charge removing means for electrostatically adsorbing the sheet-like medium to the fixing rotating body at the downstream end in the sheet-like medium conveying direction of the supporting means for supporting the fixing rotating body The pressure rotator is provided in the nip portion and is in pressure contact with the transfer fixing rotator via the fixing rotator.
According to a third aspect of the present invention, in the transfer fixing apparatus according to the second aspect, the charging unit is an upstream end of the supporting unit that supports the fixing rotator in the sheet medium conveying direction, and the toner is applied to the sheet medium. And a means for charging by applying a bias voltage having a polarity opposite to that.
According to a fourth aspect of the present invention, there is provided the transfer fixing apparatus according to the second or third aspect, wherein the charge eliminating means is a downstream end portion of the supporting means for supporting the fixing rotator in the sheet-like medium conveying direction. It was decided to be a means for removing the charge.
According to a fifth aspect of the present invention, in the transfer fixing device according to any one of the second to fourth aspects, the charging means is a means for applying a bias voltage between the transfer fixing rotator and the fixing rotator.
According to a sixth aspect of the present invention, in the transfer fixing apparatus according to the first aspect, as a means for electrostatically attracting the sheet-like medium to the fixing rotator, a sheet-like medium conveyance direction among the support means for supporting the fixing rotator. Charging means for charging the sheet-like medium is provided at the upstream end of the sheet, and among the supporting means for supporting the fixing rotator, the downstream end in the sheet-like medium transport direction is opposed to the transfer fixing rotator. It was decided to have a pressure rotator.
According to a seventh aspect of the present invention, in the transfer fixing apparatus according to the sixth aspect, the charging means is a means for charging the sheet-like medium by applying a bias voltage having a polarity opposite to that of the toner.
According to an eighth aspect of the present invention, in the transfer fixing device according to the sixth or seventh aspect, a sheet-like medium with respect to the fixing rotator is provided at the downstream end in the sheet-like medium conveyance direction of the support means for supporting the fixing rotator. It was decided to provide a static elimination means for eliminating the charge related to the electrostatic adsorption.
According to a ninth aspect of the present invention, in the transfer fixing device according to any one of the sixth to eighth aspects, the charging unit is a unit that applies a bias voltage between the transfer fixing rotator and the fixing rotator.
According to a tenth aspect of the present invention, in the image forming apparatus that obtains a recorded image by transferring and fixing the toner image formed on the photosensitive member to a sheet-like medium by the transfer and fixing device, any of the first to ninth aspects is used as a transfer and fixing means. The transfer fixing device described above was provided.

  In the present invention, the sheet-like medium that has been transferred and fixed is prevented from being wound around the transfer-fixing member by electrostatically adsorbing the sheet-like medium to the fixing rotator, and the force applied to the electrostatic adsorption is reduced after the transfer-fixing. Alternatively, it can be easily separated from the fixing rotating body.

Embodiments of the present invention will be described below.
[1] First Embodiment FIG. 1 is a schematic configuration diagram showing a first embodiment of an image forming apparatus including a transfer fixing device of the present invention. An outline of the configuration and operation when the transfer fixing device of the first embodiment is applied to an electrophotographic tandem color copier will be described. The color copying machine has an image forming unit 1 located at the center of the apparatus main body, a paper feeding unit 15 located below the image forming unit 1, and an image reading unit (not shown) located above the image forming unit 1. is doing.

  An intermediate transfer belt 2 as an intermediate transfer body having a transfer surface extending in the horizontal direction is disposed in the image forming unit 1, and the upper surface of the intermediate transfer belt 2 has a color complementary to the color separation color. A configuration for forming an image is provided. That is, the photoconductors 3Y, 3M, 3C, and 3B as image carriers capable of carrying images of toners of complementary colors (yellow Y, magenta M, cyan C, and black B) are transfer surfaces of the intermediate transfer belt 2. Are juxtaposed along.

  Each of the photoconductors 3Y, 3M, 3C, and 3B is configured by a drum that can rotate in the same direction (counterclockwise direction), and around the charging device 4 that performs image forming processing in the rotation process, light A writing device 5, a developing device 6, a primary transfer device 7, and a cleaning device 8 are provided as writing means. The alphabets Y, M, C, and B added to the reference numerals correspond to the toner colors as in the photosensitive member 3.

  Each developing device 6 accommodates each color toner. The intermediate transfer belt 2 is wound around driving rollers 9 and 10 and a driven roller 11. A cleaning device 12 for cleaning the surface of the intermediate transfer belt 2 is provided at a position facing the driven roller 11 with the intermediate transfer belt 2 in between.

  The surface of the photoreceptor 3Y is uniformly charged by the charging device 4, and an electrostatic latent image is formed on the photoreceptor 3Y based on image information from an image reading unit (not shown). The electrostatic latent image is visualized as a toner image by a developing device 6Y containing yellow toner, and the toner image is primary-transferred onto the intermediate transfer belt 2 by a primary transfer device 7Y to which a predetermined bias is applied. Transcribed.

  The other photoconductors 3M, 3C, and 3B also form similar images only with different toner colors, and the toner images of the respective colors are sequentially transferred onto the intermediate transfer belt 2 and superimposed. After the transfer, the toner remaining on the photosensitive member 3 is removed by the cleaning device 8, and after the transfer, the potential of the photosensitive member 3 is initialized by a neutralizing lamp (not shown) and is prepared for the next image forming step.

  The paper feeding unit 15 feeds the paper feeding tray 14 on which the recording medium P as a sheet-like medium is stacked and stored, and feeds the recording medium P in the paper feeding tray 14 one by one in order from the top. A paper roller 16, a pair of conveyance rollers 17 and 18 that convey the fed recording medium P, and a transfer fixing roller that is positioned downstream of the conveyance direction after temporarily stopping the recording medium P and correcting the oblique displacement. A registration roller pair 18 that feeds toward a nip N, which will be described later, is provided at a timing when the leading edge of the 24 images coincides with a predetermined position in the transport direction.

  In the vicinity of the driving roller 9, a transfer fixing device 20 is provided. In the transfer fixing device 20, a transfer fixing roller 24 and a pressure roller 34 are provided opposite to each other via a conveyance belt 31, and are pressed against each other by a pressure unit such as a spring 23 to form the nip N.

  A toner image T (hereinafter, also simply referred to as “toner”) primarily transferred from the photoreceptors 3Y, 3M, 3C, and 3B onto the intermediate transfer belt 2 is applied to the drive roller 9 by a secondary bias applying unit (not shown). The image is secondarily transferred to the transfer fixing roller 24 by electrostatic force by bias (including superposition of AC, pulse, etc.).

  As shown in FIG. 1, between the intermediate transfer belt 2 and the transfer fixing roller 24, a heat shielding member or a heat movement inhibiting member that suppresses heat radiation (heat movement) from the transfer fixing roller 24 to the intermediate transfer belt 2. A heat insulating plate 19 is provided.

  The heat insulating plate 19 is formed in a shape having an opening so as to suppress heat radiation to the intermediate transfer belt 2 as much as possible without inhibiting secondary transfer from the intermediate transfer belt 2 to the transfer fixing roller 24. The fixing device main body and the image forming apparatus main body may be provided on either side.

  The heat transfer inhibiting member is preferably a plate-like member having a metallic luster with low emissivity, and an excellent effect can be obtained particularly when two metal sheets are arranged with a minute gap or a heat insulating material interposed therebetween. When a thin plate containing a micro heat pipe structure that is used for CPU cooling of a notebook computer is used, the heat transfer inhibiting member can be kept at a low temperature and heat transfer can be suppressed.

  In this embodiment, the heat of the intermediate transfer belt 2 is transferred between the transfer portion of the intermediate transfer belt 2 with respect to the transfer fixing roller 24 (the portion facing the transfer fixing roller 24) and the transfer portion with respect to the most upstream photoreceptor 3B. A cooling roller 13 is provided as a cooling member to be removed.

  The cooling roller 13 is made of a material having high thermal conductivity, and rotates in contact with the intermediate transfer belt 2. In the present embodiment, the heat insulating plate 19 and the cooling roller 13 are provided at the same time. However, either one may be provided. According to this embodiment, the temperature of the intermediate transfer member can be reduced, and thermal deterioration on the intermediate transfer member side can be suppressed. Further, the degree of freedom in designing the transfer fixing member can be increased.

  The transfer fixing roller 24 is made of a metal pipe-shaped cored bar 22 such as aluminum, an elastic layer 27 of about 0.05 to 0.5 mm on the surface, and PFA or PTFE, which is a fluororesin material of 5 to 30 μm. The release layer 28 is coated. Further, a halogen heater 21 is provided inside the transfer fixing roller 24 as a heating means for heating the toner image on the surface layer of the transfer fixing roller 24.

  Since it is necessary to hold an image for the length of the recording medium, the outer diameter of the transfer fixing roller 24 is equal to or longer than the length of the recording medium P. Further, a thermistor (not shown) provided in a non-image area for measuring the surface temperature of the transfer fixing roller 24 and a temperature controller (not shown) for controlling on / off of the halogen heater 21 based on the surface temperature are provided. The temperature can be controlled independently.

  Further, a transfer bias is applied between the release layers by forming the release layer of the transfer fixing roller 24 from a conductive fluorine-based resin material in which a conductive substance such as carbon is dispersed and connecting it to a cored bar. Thus, the transfer bias can be lowered and scattering during transfer can be suppressed.

  The supporting means for supporting the conveying belt 31 as the fixing rotator includes a supporting roller 32 positioned at a substantially upstream end of the upper side of the conveying belt 31 in the recording medium conveying direction indicated by an arrow, and a substantially downstream end. And a roller such as a pressure roller 34 that is a pressure rotating body that is in pressure contact with the transfer fixing roller 24 via the conveyance belt 31. .

  The pressure roller 34 has a pressure spring 23 and presses the conveyance belt 31 against the transfer fixing roller 24 at the nip N. When paying attention to the upper side of the conveying belt 31, a charging roller 36 is used as a charging means for charging the recording medium P to be electrostatically attracted to the conveying belt 31 above the support roller 32 positioned at the upstream end. The recording medium P can be charged with a positive charge having a polarity opposite to that of the toner. The electrostatic force due to the charging causes the recording medium P to be attracted to the conveyance belt 31 and contributes to transferring the toner on the transfer fixing roller 24 to the recording medium P at the nip N.

  Of the support means of the transport belt 31, the support belt 33 located above the support roller 33 located at the downstream end in the transport direction of the recording medium P when attention is paid to the stretched portion on the upper side of the transport belt 31 together with the transport belt 31 A neutralizing brush 37 as a neutralizing unit is installed in such a manner that the charged potential of the conveyed recording medium P can be neutralized, and the positive charge of the recording medium P can be neutralized. By such charge removal, the electrostatic attraction force of the recording medium P to the conveyance belt 31 is reduced or eliminated, and the recording medium P conveyed by the support roller 33 is easily separated from the conveyance belt 31 by curvature separation and discharged. In order to achieve good curvature separation, it is desirable that the support roller 33 has a small diameter of about 15 mm or less.

  A modification of the embodiment shown in FIG. 1 is shown in FIG. In the embodiment shown in FIG. 1, no means for applying a bias to the pressure roller 34 is provided. However, as shown in FIG. 2, a power supply is used to apply a bias potential to assist the transfer and fixing to the pressure roller 34. Bias applying means such as connection may be provided.

  Next, operations such as transfer and fixing will be described with reference to FIG. The toner image T transferred from the photoreceptor 3 onto the intermediate transfer belt 2 is negatively charged, and is biased so that the drive roller 9 side is −0.5 kV to 2 kv, and the core of the transfer fixing roller 24 is 0V. Is applied, the transfer belt 2 is supported by the drive roller 9 and is sequentially transferred to the transfer fixing roller 24 at a portion in contact with the transfer fixing roller 24. At this time, the surface temperature of the transfer fixing roller 24 is heated to a predetermined temperature by the halogen heater 21.

  After the toner image T thus transferred is completely held on the transfer fixing roller 24, a surface image is formed. The toner image of the transfer fixing roller 24 is transferred at the nip N onto the recording medium P sent out from the paper supply unit 15 and held and conveyed on the transfer belt 31, and a fixed image is formed. After being separated from the conveyor belt 31 at the support site, the paper is discharged onto a paper discharge tray (not shown). This separation is satisfactorily performed because the electrostatic attraction force to the recording belt P with respect to the conveyance belt 31 is lost due to the neutralization action on the recording medium P of the static elimination brush 37 as the static elimination means.

  The recording medium P sent from the paper supply unit 15 through the paper supply roller 16, the conveyance roller pair 17, and the registration roller pair 18 is opposite to the toner T by the charging roller 36 that is opposed to the conveyance belt 31 via the support roller 32. By being charged by applying a bias voltage of polarity, it is electrostatically attracted to the conveyor belt 31, and further conveyed toward the nip N by the conveyor belt 31.

  In FIG. 1, since the charge of the toner is negative, the polarity of the bias voltage applied to the charging roller 36 is positive. The unfixed toner image transferred to the transfer / fixing roller 24 is transferred to the recording medium P that is electrostatically attracted to the transport belt 31 and is transported by being pressed by the nip N, and is fixed. The recording medium P having the fixing toner image is separated from the transfer fixing roller 24 and further conveyed. The recording medium P to be conveyed is neutralized by a neutralizing brush 37 provided above the support roller 33 on the downstream side of the nip N, separated from the conveyance belt 31 by the curvature separation of the support roller 33, and discharged.

[2] Second Embodiment FIG. 3 shows a second embodiment of the transfer fixing apparatus of the present invention. The configuration of the second embodiment is substantially the same as that of the first embodiment, and members having the same functions and configurations are denoted by the same reference numerals. The difference is as means for heating the toner T on the transfer fixing roller 24. Induction heating method is used. Therefore, the transfer fixing roller 24 has a configuration in which a metal pipe-shaped core metal 22 such as aluminum and a metal conductive layer 26 as a heat generating layer are provided around the core metal 22, and the surface of the metal conductive layer 26 is provided. Is coated with an elastic layer 27 of about 0.05 to 0.5 mm and a surface of the elastic layer 27 with a release layer 28 such as PFA or PTFE which is a fluorine resin material of 5 to 30 μm.

  An exciting coil 25 is installed just before the nip N in the vicinity of the transfer fixing roller 24 (immediately before the upstream side), and the transfer fixing roller 24 can be heated by induction heating. The metal conductive layer is nickel, stainless steel, aluminum, a composite material of aluminum and stainless steel, or the like.

  Other configurations, image formation, and fixing operations are the same as those in the first embodiment. The toner T held on the transfer fixing roller 24 is heated to a predetermined temperature by induction heating immediately before the nip N, and is transferred and fixed to the recording medium P at the nip N.

[3] Third Embodiment FIG. 4 shows a third embodiment of the transfer fixing apparatus of the present invention. In the third embodiment, members having the same functions and configurations as those of the first embodiment are denoted by the same reference numerals, and a fixing rotation including a transport belt 31 and a roller that bears the transport belt 31 is provided. The body 30 drives the support roller 32 disposed upstream from the nip N in the recording medium conveyance direction, the pressure roller 38 serving as a support roller and a pressure roller disposed in the nip N portion, and the conveyance belt 31. It is comprised from the drive roller 35 grade | etc.,.

  As in the first embodiment, a charging roller 36 as a charging unit is installed above the support roller 32, and a positive charge having a polarity opposite to that of the toner is charged to the recording medium P and the conveyance belt 31 by a power source. Can do. In the vicinity of the downstream end of the conveying belt 31, that is, in the vicinity (downstream side) of the pressure roller 38 located at the downstream end when attention is paid to the upper side of the conveying belt 31, the recording medium P is neutralized and suction force is obtained. A neutralizing needle 39 is installed as a neutralizing means for canceling, and the positive charge of the recording medium P can be neutralized immediately after the downstream side of the nip N in the rotational direction of the conveying bell 31.

  A pressure spring 23 is attached to the pressure roller 38 and can be pressurized at the nip N. Further, a power supply device for applying a transfer bias to the pressure roller 38 is provided. A bias can be applied. FIG. 4 shows only the fixing rotator 30 including the transfer fixing roller 24, the conveyance belt 31, and the roller that bears the conveyance belt 31.

  The operations such as image formation and fixing are substantially the same as those in the first embodiment. The recording medium P is charged by applying a bias having a polarity opposite to that of the toner by the charging roller 36 to be electrostatically attracted to the conveyance belt 31. Transport to nip N.

  The unfixed toner image transferred from the photoconductor to the transfer fixing roller 24 is pressed and fixed to the recording medium P conveyed to the nip N while being electrostatically attracted to the conveyance belt 31. Further, a positive bias is applied to the pressure roller 38 here, and the bias is applied so that the cored bar 22 of the transfer and fixing roller 24 becomes 0 V, thereby preventing the toner image from being thermally transferred to the recording medium P. At the same time as electrical assistance, it prevents electrostatic offset of toner.

Thereafter, the recording medium P having the fixed toner image is neutralized by the neutralizing needle 40 provided in the vicinity of the nip N, separated from the transfer fixing roller 24 and the conveying belt 31 by the curvature separation by the support roller 38, and further conveyed. In the third embodiment, the fixing temperature can be lowered as compared with the first embodiment, and the transfer fixing device can be downsized.

[4] Fourth Embodiment FIG. 5 shows a fourth embodiment of the transfer fixing apparatus according to the present invention. In the fourth embodiment, members having the same functions and configurations as those of the first embodiment are denoted by the same reference numerals, and the image forming unit 1 located in the central part of the apparatus main body, A sheet feeding unit 15 positioned below the image forming unit 1 and an image reading unit (not shown) positioned above the image forming unit 1 are provided.

  An intermediate transfer belt 240 ′ is disposed in the image forming unit 1, and is wound around the driving roller 10, the driven roller 11, and the transfer fixing roller 240.

  In the transfer fixing device 200, a transfer fixing roller 240 having a heat source and a pressure roller 34 are provided opposite to each other via an intermediate transfer belt 240 ′ and a conveyance belt 31, and are pressed against each other by a pressing means such as a spring 23 to form a nip N. Forming.

  The toner image T is transferred and fixed to the recording medium P at a nip N formed by the transfer fixing roller 240 and the pressure roller 34.

  Further, similarly to the first embodiment, a cooling roller 13 is provided as a cooling member that removes heat from the intermediate transfer belt 240 ′. The cooling roller 13 is made of a material having high thermal conductivity and rotates in contact with the intermediate transfer belt 240 '.

  The transfer fixing roller 240 is provided with a halogen heater 21 as a heating means for heating the toner image inside a cored bar 22 provided therein. The cored bar 22 is covered with a surface layer, and the intermediate transfer belt 240 ′ is in contact with the surface layer. Further, a thermistor (not shown) provided on the transfer fixing roller 240 ′ for measuring the temperature of the nip N and a temperature controller (not shown) for controlling on / off of the halogen heater 21 based on the respective surface temperatures are provided. Yes, you can control the temperature independently.

  Operations such as transfer and fixing will be described. The toner image T transferred from the photoreceptor onto the intermediate transfer belt 240 ′ is conveyed to the nip N. At this time, the nip N of the intermediate transfer belt 240 ′ also serving as a transfer fixing rotator is heated to a predetermined temperature by the transfer fixing roller 24 having the halogen heater 21.

  The toner image T is heated in the nip N and transferred and fixed to the recording medium P. The subsequent operation is substantially the same as in the first embodiment. A fixed image is formed on the recording medium P conveyed from the paper supply unit 15, separated from the conveyance belt 31, and discharged.

  In accordance with the configuration of FIG. 1, the recording medium P is charged to be electrostatically attracted to the conveyance belt 31 above the support roller 32 positioned at the upstream end when attention is paid to the upper side of the conveyance belt 31. A charging roller 36 is installed as a charging means. When attention is paid to the upper side of the conveyor belt 31, the recording medium P is discharged above the support roller 33 located at the downstream end to release the suction force. A neutralizing brush 37 is installed as a means.

  By applying a bias voltage having a polarity opposite to that of the toner T by the charging roller 36, the recording medium P is charged by the charging roller 36 from the paper feeding unit 15 through the paper feeding roller 16, the conveying roller pair 17, and the registration roller pair 18. It is electrostatically attracted to the transport belt 31 and transported to the nip N.

  In the embodiment of FIG. 5, since the charge of the toner is negative, the polarity of the bias voltage applied to the charging roller 36 is positive. The unfixed toner image formed on the intermediate transfer belt 240 ′ is transferred and fixed in pressure contact with the recording medium P conveyed to the nip N while being electrostatically attracted to the conveyance belt 31.

  The recording medium P having the fixed toner image is separated from the intermediate transfer belt 240 'and further conveyed. The recording medium P to be conveyed is neutralized by the neutralizing brush 37 provided above the support roller 33 provided on the downstream side (left end portion in the drawing) of the conveyance belt 240 ′ and separated by the curvature separation of the support roller 33. The paper is ejected.

  Although not shown, in the first to fourth embodiments, a conventional separation claw may be provided immediately after the nip N as a recording medium separation unit. A power supply capable of variably adjusting the output is connected to each charging means and static elimination means.

In the above embodiment, since the recording medium passes through the transfer fixing process in a state of being electrostatically attracted to the fixing rotating body having the conveying means, the fixing rotation can be performed without the transfer-fixed recording medium being wound around the transfer fixing member. Transported downstream of the body. Accordingly, it is possible to prevent the occurrence of a jam due to the winding of the paper, the problem that the recording medium wound around the transfer fixing member damages the intermediate transfer member, and the problem that the recording medium is damaged due to contact with the heat source for heating the toner.
In addition, it is possible to prevent occurrence of abnormal images such as wrinkles, image blurring, and image blur that may occur due to variations in the entry position and the entry angle when the recording medium enters the transfer fixing nip.
Further, in order to prevent the recording medium from being wound around the transfer fixing member in the conventional transfer fixing apparatus, it has been necessary to provide a white spot on the unfixed image. A fixed image is formed on the entire surface, and a stable recording medium can be conveyed.
In the transfer and fixing process, since the recording medium has a charge opposite in polarity to that of the toner, it assists in transferring and fixing the toner to the recording medium, and the fixing temperature can be lowered. Furthermore, the effect becomes more remarkable by applying a bias between the transfer fixing rotator and the fixing rotator.

FIG. 2 is a diagram illustrating a main configuration of an image forming apparatus including a transfer fixing device. FIG. 2 is a diagram illustrating a main configuration of an image forming apparatus including a transfer fixing device. FIG. 2 is a diagram illustrating a main configuration of an image forming apparatus including a transfer fixing device. FIG. 2 is a diagram illustrating a main configuration of an image forming apparatus including a transfer fixing device. FIG. 2 is a diagram illustrating a main configuration of an image forming apparatus including a transfer fixing device.

Explanation of symbols

31 Conveyor belt (fixing rotator)
36 Charging roller 37 Static elimination brush

Claims (10)

A means for heating the electrostatically formed toner image on the transfer-fixing rotator, and a fixing for forming a nip by pressing against the transfer-fixing rotator and conveying the sheet-like medium so as to pass through the nip In a transfer fixing device having a rotating body,
The sheet-like medium is electrostatically attracted to the fixing rotator and conveyed, and the toner image is transferred and fixed from the transfer-fixing rotator at the nip portion. After the transfer and fixing, the sheet-like medium is electrostatically attracted to the fixing rotator. A transfer-fixing device, wherein charge is removed and a sheet-like medium is separated from a fixing rotator. The transfer fixing device according to claim 1.
Of the supporting means for supporting the fixing rotator, a charging means for electrostatically adsorbing the sheet-like medium to the fixing rotator at the upstream end in the sheet-like medium conveyance direction, and a supporting means for supporting the fixing rotator Of these, the downstream end portion in the sheet-like medium conveyance direction has a discharging means for discharging the charge related to the electrostatic attraction of the sheet-like medium to the fixing rotator, and the nip portion has the fixing rotator interposed therebetween. A transfer fixing device comprising a pressure rotator in pressure contact with the transfer fixing rotator. The transfer fixing device according to claim 2.
The charging means is a means for charging the sheet-like medium by applying a bias voltage having a polarity opposite to that of the toner at the upstream end in the sheet-like medium conveying direction of the supporting means for supporting the fixing rotator. Transfer fixing device. The transfer fixing device according to claim 2 or 3,
The transfer and fixing device, wherein the charge eliminating means is a means for discharging charges on the sheet-like medium at a downstream end in the sheet-like medium conveying direction of the support means for supporting the fixing rotator. The transfer fixing device according to any one of claims 2 to 4,
The transfer fixing device, wherein the charging means is means for applying a bias voltage between the transfer fixing rotator and the fixing rotator. The transfer fixing device according to claim 1.
As means for electrostatically adsorbing the sheet-like medium to the fixing rotator, charging means for charging the sheet-like medium at the upstream end in the sheet-like medium conveyance direction is provided among the support means for supporting the fixing rotator. ,
A transfer fixing device having a pressure rotating member facing a transfer fixing rotating member at a downstream end in a sheet-like medium conveying direction among supporting means for supporting a fixing rotating member. The transfer fixing device according to claim 6.
The transfer fixing apparatus, wherein the charging means is means for charging the sheet-like medium by applying a bias voltage having a polarity opposite to that of the toner. The transfer fixing device according to claim 6 or 7,
Of the support means for supporting the fixing rotator, the downstream end in the sheet-like medium conveyance direction is equipped with a charge eliminating means for eliminating the charge associated with electrostatic adsorption of the sheet-like medium to the fixing rotator. Transfer fixing device. The transfer fixing device according to any one of claims 6 to 8,
The transfer fixing device, wherein the charging means is means for applying a bias voltage between the transfer fixing rotator and the fixing rotator. In an image forming apparatus for obtaining a recorded image by transferring and fixing a toner image formed on a photosensitive member to a sheet-like medium by a transfer and fixing device,
An image forming apparatus comprising the transfer fixing device according to claim 1 as a transfer fixing unit.

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