JP2011197321A - Image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming system which is free of shifting cost to users who do not require a special toner image and lower in cost, and superior in durability and usability for the users requiring the special toner image.SOLUTION: In the image forming system in which a second image forming device 2 for forming a transparent image is optionally loaded with respect to a first image forming device 1 forming a color image, charging devices 12Y, 12M, 12C and 12K in the first image forming device 1 charge photoreceptors 11Y, 11M, 11C and 11K by applying a voltage obtained by superimposing an AC component on a DC component and an charging device 32 in the second image forming device 2 electrifies a photoreceptor 31, by applying a voltage having only a DC component.

Description

  The present invention relates to an image forming system in which a second image forming apparatus that forms a special toner image can be optionally mounted on a first image forming apparatus that forms a toner image using an electrophotographic system.

  In recent years when image quality has been diversified, various image forming apparatuses have been proposed that can realize special image quality that cannot be obtained by using normal toner, such as glossiness and stereoscopic effect.

  For example, Patent Document 1 proposes an image forming apparatus that transfers and fixes a transparent toner image together with normal colored toner images such as black, yellow, magenta, and cyan on a transfer material. According to this image forming apparatus, it is not necessary to incorporate a complicated mechanism as compared with the case where a transparent resin is sprayed or coated on the entire paper, and a glossy image that looks good even if plain paper is used. Can be easily obtained.

  Patent Document 2 proposes an image forming apparatus that transfers and fixes a transparent toner image after transferring and fixing a colored toner image on a transfer material. In this image forming apparatus, the transfer material on which the color toner image is transferred and fixed is re-fed through the transfer material conveyance path, and the transparent toner image is transferred onto the color toner image on the transfer material, and then the same fixing device as before To fix and output an image. According to this image forming apparatus, it is possible to prevent the occurrence of color bleeding when the colored toner image and the transparent toner image are formed in an overlapping manner, and to improve the glossiness. Furthermore, the glossiness is improved by increasing the fixing property when fixing the transparent toner image than when fixing the colored toner image, for example, by lowering the transfer speed of the transfer material.

  Patent Document 3 proposes an image forming apparatus that transfers and fixes a color toner image and / or a transparent toner image onto a transfer material, and then transfers and fixes the transparent toner image onto the transfer material. In this image forming apparatus, the ultimate melt viscosity η1 of the toner in the fixing nip in the first fixing step and the ultimate melt viscosity η2 of the toner in the fixing nip in the second fixing step are (final melt viscosity η1). <(Achieved melt viscosity η2) is satisfied. As a result, the melting state of the transparent toner image in the second fixing step can be suppressed more than in the first fixing step, so that the transparent toner image obtained in the second image forming step can be obtained in the first image forming step. Compared to a transparent toner image to be produced, a low gloss portion can be obtained. That is, it is possible to output a high gloss part and a low gloss part for an arbitrary part in the same image plane.

  However, the image forming apparatuses proposed in Patent Documents 1 to 3 have a revolver system including at least five developing machines of yellow, cyan, magenta, black, and transparent toner in the same image forming apparatus, or five. A tandem system including the above developing device and photoconductor drum is used, resulting in a very high production cost. Although the number of users who need transparent toner is increasing, for most users, the output image is only a monochrome or four-color image, so image formation with transparent toner is performed in advance on all image forming apparatuses. Making it possible is not appropriate due to high costs.

  On the other hand, an image forming system has been proposed in which a second image forming machine using special toner can be optionally installed on the first image forming machine serving as a basic machine using colored toner (for example, Patent Document 4). . In this image forming system, when a special image is desired, the first image forming machine serving as a basic machine is left as it is, and a second image forming machine is attached thereto. On the other hand, for a user who does not desire a special image, a configuration in which the second image forming machine is not provided can be adopted, and an extra cost is not borne.

  However, in the image forming system including the first image forming machine described above and the second image forming machine that is optionally mounted on the first image forming machine, if the same charging unit is used for the first image forming machine and the second image forming machine, There was an inconvenience to explain.

  In an image forming apparatus that forms a color image, not only characters but also halftone images such as photographs are frequently used, and high image quality is required. In order to obtain a high-quality halftone image, it is necessary to uniformly charge a photoconductor as an image carrier. Therefore, in general, in a color image forming apparatus, a charging unit that applies a voltage in which an AC component is superimposed on a DC component is used as a charging unit. However, a power source that applies an AC component voltage is more expensive than a power source that applies only a DC component voltage. When an AC component voltage is applied, the surface of the photoconductor deteriorates due to a charging hazard and gradually disappears from the photoconductive layer, making it difficult for the photoconductor to maintain the same performance over a long period of time. As a countermeasure, the surface of the photoconductor is protected from an alternating voltage by applying a protective agent such as zinc stearate to the surface of the photoconductor. However, if the toner remaining on the photoreceptor is to be recycled, there is a problem that it becomes difficult to reuse the toner because this protective agent is mixed to deteriorate the chargeability of the toner.

  On the other hand, a special toner image such as a transparent toner is a solid image for most purposes. Therefore, at the time of forming the special toner image, the charging performance as that at the time of forming the color image is not necessarily required, and as described above, the charging means for applying the voltage in which the AC component is superimposed on the DC component is not necessarily required.

  The present invention has been made in view of the above problems. Its purpose is to provide an image forming system that does not incur costs for users who do not require special toner images, and is low in cost and excellent in durability and usability for users who require special toner images. Is to provide.

In order to solve the above-mentioned problems, the invention of claim 1 includes a charging unit that uniformly charges the image carrier and an exposure unit that exposes the uniformly charged image carrier to form an electrostatic latent image. A first image forming apparatus having a developing unit for developing an electrostatic latent image on the image carrier and forming a colored toner image superimposed on a recording medium; and a charging unit for uniformly charging the image carrier And an exposure unit that exposes the uniformly charged image carrier to form an electrostatic latent image and a developing unit that develops the electrostatic latent image on the image carrier to form a superimposed color toner image. And a second image forming apparatus for forming a special toner image on the recording medium, wherein the second image forming apparatus is optionally mounted on the first image forming apparatus. In the charging means, a voltage obtained by superimposing an AC component on a DC component is applied. Charging the Rizo bearing member, a charging means in the second image forming apparatus is characterized in that for charging the image bearing member by applying a voltage of only a DC component.
According to a second aspect of the present invention, in the image forming system of the first aspect, the second image forming apparatus includes a toner reuse mechanism for reusing the toner discharged at the time of image formation. is there.
According to a third aspect of the present invention, in the image forming system according to the first or second aspect, when image formation is performed on both sides of the recording medium, a colored toner image is transferred onto both sides of the recording medium by the first image forming apparatus. After fixing, the second image forming apparatus transfers and fixes the transparent toner image on both sides of the recording medium.
In the present invention, the charging means of the first image forming apparatus applies a voltage in which an alternating current component is superimposed on a direct current component to uniformly charge the image carrier. The charging unit of the second image forming apparatus applies a voltage of only a direct current component. According to the present invention, even for a user who needs a special toner image, it is possible to reduce the cost by using a DC power source that is less expensive than an AC power source as a charging unit of an optional second image forming apparatus. is there. Further, since the image carrier of the second image forming apparatus is not affected by the voltage of the AC component, the performance of the image carrier can be maintained over a long period of time, and the durability can be improved. Further, since it is not necessary to use a protective agent for the image carrier of the second image forming apparatus, toner recycling is facilitated in the second image forming apparatus.

  The present invention does not incur a cost for a user who does not need a special toner image, and an image forming system which is low in cost and excellent in durability and usability for a user who needs a special toner image. There is an excellent effect that it can be provided.

1 is a schematic configuration diagram showing an image forming system according to an embodiment.

  Hereinafter, an embodiment of an image forming system that forms an image by an electrophotographic method will be described as an image forming system to which the present invention is applied. FIG. 1 is a schematic configuration diagram showing an image forming system according to the present embodiment. This image forming system includes a first image forming apparatus 1 and a second image forming apparatus 2 that is optionally mounted thereon.

  First, the basic configuration of the first image forming apparatus 1 will be described. The first image forming apparatus 1 includes four process units 10Y, 10M, 10C, and 10K for forming colored toner images of yellow (Y), magenta (M), cyan (C), and black (K). Yes. In the following, the subscripts Y, M, C, and K indicate yellow, magenta, cyan, and black, respectively. Each of the process units 10Y, 10M, 10C, and 10K includes photoconductors 11Y, 11M, 11C, and 11K, which are image carriers that carry toner images of respective colors. Around these photoconductors 11Y, 11M, 11C, and 11K, charging devices 12Y, 12M, 12C, and 12K that uniformly charge the surface of each photoconductor 11 and the surfaces of each photoconductor 11 that is uniformly charged are provided. Exposure devices 13Y, 13M, 13C, and 13K that form an electrostatic latent image by exposure based on image data, and developing devices 14Y, 14M, 14C, and 14K that develop an electrostatic latent image formed on the surface of each photoconductor 11. Cleaning devices 15Y, 15M, 15C, 15K, etc. are provided for cleaning the surface of each photoconductor 11 after the toner image is transferred. The image data is image information obtained by reading a document by an external scanner (not shown), image information sent from an external personal computer, and the like. Further, the process units 10Y, 10M, 10C, and 10K support various devices 12, 14, and 15 disposed around the photoconductor 11 as a single unit on a common support. It can be attached to and detached from the main body of the forming apparatus 1.

  The first image forming apparatus 1 also includes a transfer unit 20 that transfers the colored toner images formed on the photoreceptors 11Y, 11M, 11C, and 11K to the paper P. The transfer unit 20 includes an intermediate transfer belt 21 that is stretched by a plurality of rollers including a driving roller and is driven to rotate in the direction of an arrow in the figure. The intermediate transfer unit 20 sandwiches the intermediate transfer belt 21 between the photoreceptors 11Y, 11M, 11C, and 11K and primary transfer rollers 22Y, 22M, 22C, and 22K to which a predetermined voltage is applied to form a primary transfer nip. . In addition, the intermediate transfer unit 20 forms a secondary transfer nip by sandwiching the intermediate transfer belt 21 between the secondary transfer backup roller 23 and the secondary transfer roller 24 to which a predetermined voltage is applied. Further, the intermediate transfer unit 20 includes a cleaning device (not shown) that removes transfer residual toner remaining on the intermediate transfer belt 21. The colored toner images on the photoreceptors 11Y, 11M, 11C, and 11K formed by the process units 10Y, 10M, 10C, and 10K are sequentially superimposed and primarily transferred onto the intermediate transfer belt 21 at the primary transfer nip. The four-color superimposed color toner image transferred onto the intermediate transfer belt 21 is secondarily transferred onto the paper P at the secondary transfer nip.

  Further, the first image forming apparatus 1 conveys a sheet below the transfer unit 20 in a paper feed cassette 25, a registration roller pair (not shown), the first fixing device 26, and the housing of the first image forming apparatus 1. A first paper transport path 27 and the like are provided. The paper feed cassette 25 is configured so as to be able to be taken in and out of the housing of the first image forming apparatus 1, and sends out the uppermost paper of the paper P to be stored one by one toward the registration roller pair. The registration roller pair sandwiches the paper P supplied by the paper feed cassette 25 between the rollers, and sends it to the secondary transfer nip at a timing that can be synchronized with the four-color superimposed color toner image on the intermediate transfer belt 21. As will be described later, the first fixing device 26 sandwiches the paper P in a fixing nip formed by contact between a fixing roller 26a containing a heat source such as a halogen lamp and a pressure roller 26b pressed toward the fixing roller 26a. The toner image is fixed by the action of heating or pressing. As will be described later, the first paper transport path 27 includes a first transfer fixing paper transport path 27 a for guiding the paper P fed from the paper feed cassette 25 to the secondary transfer nip and the first fixing device 26. The sheet P having undergone the transfer and fixing process on one side is constituted by a first reverse sheet conveyance path 27b and the like for reversing the sheet P with a switching claw (not shown) and guiding it again to the secondary transfer nip.

  Here, for the charging devices 12Y, M, C, and K of the first image forming apparatus 1, an AC power source that applies a voltage in which an AC component is superimposed on a DC component is used. Thus, the charging devices 12Y, M, C, and K can uniformly and uniformly charge the photoconductors 11Y, M, C, and K. As a result, the process units 10Y, 10M, 10C, and 10K can sufficiently cope with halftone images that require high image quality. Further, since the surfaces of the photoconductors 11Y, M, C, and K are liable to be deteriorated by using the charging devices 12Y, M, C, and K, it is preferable to apply a protective agent such as zinc stearate to the photoconductor surface.

  Next, a basic configuration of the second image forming apparatus 2 will be described. The second image forming apparatus 2 is optionally mounted on the first image forming apparatus 1 according to the will of a user who desires to perform glossiness imparting processing on an image as necessary.

  The second image forming apparatus 2 includes a process unit 30 for forming a transparent toner image that becomes a special toner image. The process unit 30 includes a charging device 32, an exposure device 33, a developing device 34, a transfer roller 36, a cleaning device 35, and the like around a drum-shaped photoconductor 31. The exposure device 33 of the process unit 30 forms a solid electrostatic latent image by exposing the region corresponding to the glossiness imparting region on the photoreceptor 31 uniformly charged by the charging device 32 by the exposure device. . The developing device 34 develops the electrostatic latent image with a transparent toner to form a transparent toner image. The transfer roller 36 to which a predetermined voltage is applied sandwiches the paper P between the photoreceptor 31 and forms a transfer nip. The transparent toner image developed on the photoreceptor 31 is transferred to the paper P at the transfer nip. The first image except that the process units 10Y, M, C, and K of the first image forming apparatus 1 use normal colored toner, whereas the process unit 30 of the second image forming apparatus 2 uses transparent toner. The configuration of the forming apparatus 1 and the second image forming apparatus 2 are the same. As the transparent toner, a toner having no pigment component added to a colored toner can be used.

  In addition, the second image forming apparatus 2 includes a second fixing device 37, a second paper transport path 38 for transporting paper in the second image forming apparatus 2, and the like. As will be described later, the second fixing device 37 sandwiches the sheet P in a fixing nip formed by contact between a fixing roller 37a including a heat source such as a halogen lamp and a pressure roller 37b pressed toward the fixing roller 37a. The toner image is fixed by the action of heating or pressing. The transparent toner used in the present embodiment is a white toner having a white color before being subjected to the heat fixing process by the second fixing device 37. However, when the heat fixing process is performed, the transparent toner is changed to a transparent toner. Have. The second paper transport path 38 is a second transfer fixing paper transport path 38 a for guiding the paper P discharged from the first image forming apparatus 1 to the transfer nip of the process unit 30 and the second fixing device 37, and is transparent to one side. The second reverse paper conveyance path 38b for reversing the paper P after the toner image transfer and fixing processing by a switching claw (not shown) and guiding it again to the transfer nip, the paper P discharged from the first image forming apparatus 1 as it is. It comprises a discharge conveyance path 38 and the like for discharging outside.

  Here, the charging device 32 of the second image forming apparatus 2 uses a DC power source that applies a voltage of only a DC component. By using the charging device 32 using a DC power supply, it is possible to maintain the performance of the photoreceptor 31 for a long period without using a protective agent such as zinc stearate. Further, as will be described later, in the process unit 30, since the protective agent is not mixed in the transparent toner, the transparent toner can be easily recycled.

  Note that the image forming system according to the present embodiment includes a control unit (not shown) for adjusting the position between the first image forming apparatus 1 and the second image forming apparatus 2. For example, the control unit measures a positional deviation between a color toner image formation position on the paper P in the first image forming apparatus 1 and a transparent toner image formation position in the second image forming apparatus 2, and then determines the result. Accordingly, an inter-machine alignment process for correcting the formation position of the transparent toner portion can be performed. The second image forming apparatus 2 according to the present embodiment includes a test sheet storage cassette 39 for storing the test sheet T used in the inter-machine alignment process in distinction from printout paper in a general print job, A test paper transport path 38d for transporting the test sheet T is also provided. The test sheet T can be a general white sheet accommodated in a sheet feeding cassette 25 in the first image forming apparatus 1 and can be used for inter-machine alignment processing. The test sheet T accommodated therein can be reused.

  In the first image forming apparatus 1 and the second image forming apparatus 2 configured as described above, image formation is performed as follows. First, a single-side gloss imparting mode for forming a colored toner image and a transparent toner image only on the surface of the paper P will be described. For example, in the yellow process unit 10Y, the surface of the photoconductor 11Y uniformly charged by the charging device 12Y is irradiated with the laser beam modulated and deflected by the exposure device 13Y while being scanned to form an electrostatic latent image. Is done. The electrostatic latent image on the photoreceptor 11Y is developed by the developing device 14Y to become a yellow toner image. The toner image on the photoreceptor 11Y is transferred onto the paper P in the primary transfer nip that faces the primary transfer roller 22Y with the intermediate transfer belt 21 interposed therebetween. The surface of the photoreceptor 11Y after the toner image is transferred is cleaned by the cleaning device 15Y, and is prepared for the next formation of an electrostatic latent image.

  For the other process units 10M, 10C, and 10K, the above-described image forming process is executed in synchronization with the movement of the intermediate transfer belt 21, and a four-color superimposed toner image is formed on the intermediate transfer belt 21. On the other hand, the sheet fed from the sheet feeding cassette 25 is sent at a predetermined timing by a pair of registration rollers and conveyed to the secondary transfer nip. Then, the four-color superimposed toner images are collectively transferred onto the paper P at the secondary transfer nip. The paper P onto which the four-color superimposed toner images have been collectively transferred is conveyed through the first transfer fixing paper conveyance path 27a, and the toner image is fixed by the first fixing device 26. The paper P that has passed through the first fixing device 26 is sent to the second transfer fixing paper conveyance path 38a in the second image forming apparatus 2 in accordance with the conveyance path selection by the switching claw.

  In the process unit 30 in the second image forming apparatus 2, an area corresponding to a glossiness imparting area to which glossiness should be imparted by the exposure device 33 is formed on the surface of the photoreceptor 31 uniformly charged by the charging device 32. It is exposed to form a solid electrostatic latent image. The electrostatic latent image on the photoreceptor 31 is developed with the transparent toner of the developing device 34, and the developed transparent toner image is transferred to the paper P sent from the first image forming apparatus 1 at the transfer nip. . The sheet P on which the transparent toner image has been transferred is subjected to a fixing process by the heating / pressurizing action of the second fixing device 37 and is discharged outside the apparatus.

  Here, in this embodiment, the second fixing temperature in the second fixing device 37 is set lower than the first fixing temperature in the first image fixing device 26 to perform the fixing process. By lowering the second fixing temperature, the melting of the transparent toner is suppressed and the surface roughness is maintained, so that only the transparent toner image has a low glossiness. On the other hand, the four-color superimposed toner image passes through the first fixing device 26 and the second fixing device 37, so that the glossiness slightly increases. Thus, a large gloss difference can be given to the four-color superimposed toner image and the transparent toner image in the same image.

  Next, a case where the double-sided gloss imparting mode for forming a colored toner image and a transparent toner image on both the front and back sides of the paper P is selected will be described. In the first image forming apparatus 1, a transfer process and a fixing process of a four-color superimposed toner image are performed on the surface of the paper P, as in the above-described single-side gloss imparting mode. The sheet P on which the transfer process and the fixing process have been performed is sent to the first reversal conveyance path 27b in the first image forming apparatus 1 in accordance with the conveyance path selection by the switching claw, and again enters the secondary transfer nip portion. Sent out. Further, as described above, the secondary transfer process and the fixing process of the four-color superposed toner portion are also performed on the back surface of the paper P. The paper P on which the four-color superimposed toner images are formed on both the front and back sides is sent to the second transfer and fixing conveyance path 38a in the second image forming apparatus 2 according to the conveyance path selection by the switching claw.

  In the second image forming apparatus 2, as described above, the transparent toner image is transferred and fixed on the back surface of the paper P sent to the second transfer and fixing conveyance path 38a. The sheet P on which the transfer process and the fixing process have been performed is sent to the second reversal transport path 38b in the second image forming apparatus 2 according to the transport path selection by the switching claw, and is sent again to the transfer nip portion. . The surface of the paper P is also subjected to the secondary transfer process and the fixing process for the transparent toner image as described above. Then, the paper P on which the four-color superimposed color toner image and the transparent toner image are formed on both the front and back surfaces of the paper P is directly discharged out of the apparatus.

  In the case of double-sided printing, usually the front side is imaged and then the back side is imaged. In this embodiment, after the four-color superimposed toner image is formed on both sides by the first image forming apparatus 1, A transparent toner image is created on both sides by the second image forming apparatus 2. After forming a transparent toner image on the front surface with the second image forming apparatus 2, when attempting to form a four-color superimposed toner image on the back surface with the first image forming apparatus 1, the surface together with the four-color superimposed toner image The transparent toner image is also subjected to a fixing process at a high first fixing temperature by the first fixing device. For this reason, the glossiness of the transparent toner image becomes high, and the gloss difference from the four-color superimposed toner image becomes small. Therefore, in this embodiment, even in the case of double-sided printing, after the transparent toner image is formed, the images on both the front and back sides are given a gloss difference by the transparent toner by not fixing at a high temperature. Can do.

  The image forming operation described above is an operation when the mode for performing the glossiness imparting process is selected. For example, it is possible to select the non-processing mode in which the glossiness imparting process is not performed. In this case, the paper P discharged from the first image forming apparatus 1 is sent to the discharge conveyance path 38c in the second image forming apparatus 2 according to the selection of the conveyance path by the switching claw, and is directly outside the apparatus. Discharged.

  Further, in the image forming system according to the present embodiment, the process unit 30 of the second image forming apparatus 2 includes a toner reuse mechanism for reusing the transparent toner discharged when the transparent toner image is formed. ing. When the toner is reused, a protective agent such as paper dust or zinc stearate generated from the paper may adversely affect the second image forming apparatus 2, but the paper P that has passed through the first image forming apparatus is transferred to the second image forming apparatus 2. Because it is supplied, there is almost no influence of paper dust. Further, as described above, a protective agent such as zinc stearate is not used for the photoreceptor 31 of the process unit 30. Therefore, in the process unit 30, even if the toner is reused, an abnormal image due to the influence of paper dust or a protective agent does not occur, and both low cost and high quality can be achieved.

  As described above, in the image forming system according to the present embodiment, the charging device 12 of the first image forming apparatus 1 that forms a four-color superimposed toner image applies a voltage in which an AC component is superimposed on a DC component. On the other hand, the charging device 32 of the second image forming apparatus 2 that forms a transparent toner image applies a voltage of only a DC component. The image forming system according to the present invention achieves cost reduction by installing the second image forming apparatus 2 as an option with respect to the first image forming apparatus 1. By using a DC power source that is less expensive than an AC power source, it is possible to further reduce the cost. Further, in the second image forming apparatus 2, the performance of the photoreceptor 331 can be maintained for a long time without using a protective agent or the like, and the durability can be improved. Furthermore, since it is not necessary to use a protective agent for the photoconductor 31 of the second image forming apparatus 2, toner recycling is facilitated in the second image forming apparatus 2.

  Further, in the image forming system according to the present embodiment, the process unit 30 of the second image forming apparatus 2 includes a toner reuse mechanism for reusing the transparent toner discharged at the time of forming the transparent toner image. Yes. In the second image forming apparatus 2, the paper P that has passed through the first image forming apparatus is supplied, and since it is not necessary to use a protective agent for the photosensitive member 31, even if the toner is reused, these effects are caused. Abnormal images do not occur, and both low cost and high quality can be achieved.

  Further, in the image forming system according to the present embodiment, even in the case of double-sided printing, after the transparent toner image is formed, the image on either side of the front and back surfaces is made of transparent toner by not fixing at a high temperature. A gloss difference can be imparted.

1: First image forming device 2: Second image forming device 10: Process unit 20: Intermediate transfer unit 26: First fixing device 27: First paper transport path 30: Process unit 37: Second fixing device 38: First Two paper transport path

Japanese Patent Publication No. 7-38084 JP 2002-318482 A JP 2009-109926 A JP 2004-361827 A

Claims (3)

A charging unit that uniformly charges the image carrier, an exposure unit that exposes the uniformly charged image carrier to form an electrostatic latent image, and a development that develops the electrostatic latent image on the image carrier And a first image forming apparatus that forms a color toner image superimposed on a recording medium.
A charging unit that uniformly charges the image carrier, an exposure unit that exposes the uniformly charged image carrier to form an electrostatic latent image, and a developing unit that develops the electrostatic latent image on the image carrier. And a second image forming apparatus that forms a special toner image on a recording medium on which a superimposed color toner image is formed,
In the image forming system in which the second image forming apparatus is optionally mounted on the first image forming apparatus,
The charging means in the first image forming apparatus charges the image carrier by applying a voltage in which an AC component is superimposed on a DC component,
An image forming system, wherein the charging means in the second image forming apparatus charges the image carrier by applying a voltage of only a direct current component. The image forming system according to claim 1.
The image forming system, wherein the second image forming apparatus includes a toner reuse mechanism for reusing toner discharged at the time of image formation. The image forming system according to claim 1 or 2,
When image formation is performed on both sides of the recording medium, a colored toner image is transferred and fixed on both sides of the recording medium by the first image forming apparatus, and then transparent on both sides of the recording medium by the second image forming apparatus. An image forming system for transferring and fixing a toner image.

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