JP2011197319A - Image forming system - Google Patents

Abstract

The present invention does not incur a cost for a user who does not need a transparent toner image, and can give a gloss difference within the same image to a user who needs a transparent toner image. An image forming system can be provided.
A first image forming apparatus having a process unit (10Y, M, C, K) for forming a color toner image on a paper (P) and a first fixing device (26) for fixing the color toner image on the paper by heating. A process unit 30 that continuously forms a transparent toner image on the paper P output by the first image forming apparatus 1 and a second fixing device 37 that heat-fixes the color toner image and the transparent toner image on the paper P. In the image forming system including the second image forming apparatus 2 having the second image forming apparatus 2 as an option with respect to the first image forming apparatus 1, the second fixing temperature is higher than the fixing temperature in the first fixing apparatus 26. The fixing temperature in the device 37 is low.
[Selection] Figure 1

Description

  The present invention relates to an image forming system in which a second image forming apparatus for forming a transparent toner image can be optionally mounted on a first image forming apparatus for forming 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.

  However, in the image forming apparatus proposed in Patent Document 1, it is not possible to give a gloss difference in the same image in order to perform fixing after transferring all of the colored toner image and the transparent toner image onto the transfer material. Have difficulty. Even in the image forming apparatus described in Patent Document 2, it is difficult to provide a gloss difference within the same image. Although the glossiness is improved by improving the fixability at the time of fixing the transparent toner image, the glossiness of the colored toner image is uniformly improved in the same way as the transparent toner image, so that the glossiness is partially in the same image. Because there is no change.

  On the other hand, Patent Document 3 proposes an image forming apparatus in which a color toner image and / or a transparent toner image is transferred and fixed on a transfer material, and then the transparent toner image is transferred and fixed on 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 portion and a low gloss portion for an arbitrary portion within the same image plane.

  In Patent Document 4, as in “Second image forming apparatus that can be optionally mounted on the first image forming apparatus” in the means for solving the problems described later, “special attached to the image forming main body”. A sub-function addition unit capable of forming a toner image is disclosed. In this image forming apparatus, a user who does not desire a special toner image can be configured not to be provided with a sub-function adding unit, and an extra cost is not borne. However, the purpose of this sub-function addition unit is to obtain a three-dimensional image by using a thermally foamable toner. Therefore, the fixing temperature in the sub-function adding unit is set higher than the fixing temperature of the image forming main body. Therefore, when transparent toner is used as the special toner in this additional function addition unit, the glossiness of the transparent toner image and the colored toner image becomes uniform, and the glossiness is partially changed in the same image for output. It is difficult to do.

  Although the image forming apparatus proposed in Patent Document 3 can output a high gloss part and a low gloss part, at least five developments of at least yellow, cyan, magenta, black, and transparent toner in the same image forming apparatus. The tandem system including the apparatus and the photosensitive drum is used, and the production cost becomes very high. Similarly, the revolver system having five or more developing machines also has 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 full-color image. Making it possible is not appropriate due to high costs.

  The present invention has been made in view of the above problems. The purpose of the image forming system is that it does not incur a cost for a user who does not need a transparent toner image, and can give a gloss difference within the same image to a user who needs a transparent toner image. Is to provide.

In order to solve the above problems, the invention of claim 1 includes a first image forming means for forming a colored toner image on a recording medium, and a first fixing means for heating and fixing the colored toner image on the recording medium. An image forming apparatus; a second image forming unit that continuously forms a transparent toner image on the recording medium output by the first image forming apparatus; and a first image forming apparatus that heat-fixes the colored toner image and the transparent toner image on the recording medium. And an image forming system in which the second image forming apparatus is optionally mounted on the first image forming apparatus. The fixing temperature in the two fixing means is low.
According to a second aspect of the present invention, in the image forming system of the first aspect, the recording is performed on the downstream side in the recording medium movement direction from the first fixing unit and on the upstream side in the recording medium movement direction from the second fixing unit. The recording medium temperature detecting means for detecting the temperature of the medium is provided, and the second fixing means controls the fixing temperature based on the detection result from the recording medium temperature detecting means.
According to a third aspect of the present invention, in the image forming system according to the first or second aspect, the second image forming unit includes a toner reuse mechanism for reusing toner discharged at the time of image formation. Is.
According to a fourth aspect of the present invention, in the image forming system according to the first, second, or third aspect, when image formation is performed on both sides of the recording medium, the first image forming apparatus uses a colored toner image on both sides of the recording medium. After the toner is transferred and fixed, the second image forming apparatus transfers and fixes a transparent toner image on both surfaces of the recording medium.
In the present invention, when the toner image is sufficiently melted at a high fixing temperature, the smoothness of the surface is improved and the glossiness is increased. descend. Therefore, the colored toner image fixed at the high first fixing temperature by the first fixing means has high glossiness, and the transparent toner image fixed at the second fixing temperature low by the second fixing means has low glossiness. Thus, a difference in gloss occurs in the same image. A toner image that is fixed at a high fixing temperature and has a high glossiness remains high gloss even after a process of fixing at a low fixing temperature.

  The present invention does not incur a cost for a user who does not need a transparent toner image, and can provide a gloss difference within the same image to a user who needs a transparent toner image. There is an excellent effect that can be provided.

1 is a schematic configuration diagram showing an image forming system according to an embodiment. The schematic diagram which shows the measurement image which concerns on a present Example. The characteristic view which shows the glossiness difference of the measurement image which concerns on a present Example.

  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 the paper P 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. The first paper transport path 27 is 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.

  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. 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.

  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. 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 temperature of the paper P is detected downstream of the first fixing device 26 in the paper transport direction and upstream of the second fixing device 37 in the paper transport direction. There may be provided temperature detecting means. The second fixing device 37 can control the fixing temperature based on the detection result from the temperature detecting means. Thus, in the second fixing device 37, the heat given to the paper P by the first fixing device 26 can be used for the fixing process in the second fixing device 37, and fixing with a smaller amount of heat becomes possible.

  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. It may be. When the toner is reused, paper dust generated from the paper may have an adverse effect. However, since the paper P that has passed through the first image forming apparatus is supplied to the second image forming apparatus 2, There is almost no influence. Therefore, in the process unit 30 of the second image forming apparatus 2, an abnormal image due to paper dust or the like does not occur even when the toner is reused, and both low cost and high quality can be achieved.

  Hereinafter, the present invention will be described with reference to specific examples and comparative examples. In the present example and the comparative example, a Ricoh full color copying machine (imagio MP C5000) was used as the first image forming apparatus, and two Ricoh monochrome copying machines (imagio MP 5000) were connected as the second image forming apparatus. The second image forming apparatus uses transparent toner. Then, a heat fixing process was performed at the first fixing temperature and the second fixing temperature shown in the following examples and comparative examples, and measurement images were output. As shown in FIG. 2, the measurement image is formed by forming a colored toner portion 40 having a cyan toner image area ratio of 100% on the paper P by the first image forming apparatus 1, and in a half area of the colored toner portion 40. In the two-image forming apparatus 2, a transparent toner portion 41 is formed by superimposing transparent toner images having an image area ratio of 100%. Then, the glossiness of the colored toner portion 40 and the glossiness of the transparent toner portion 41 were measured. The glossiness in Examples and Comparative Examples was measured using a handy glossmeter gloss meter PG-3D (manufactured by Tokyo Denshoku Industries Co., Ltd.) at a light incident angle of 60 °. The result is shown in FIG.

[Comparative Example 1]
After the colored toner portion 40 was transferred to the paper P by the first image forming apparatus 1, the transparent toner portion was transferred by the second image forming apparatus 2 without performing fixing, and then fixed by the second fixing device 37. . The configuration of Comparative Example 1 corresponds to the configuration of the image forming apparatus disclosed in Patent Document 1.
・ No fixing of the first fixing device 26 ・ Second fixing temperature of the second fixing device 37 is 155 ° C.

[Comparative Example 2]
After the colored toner portion 40 is transferred to the paper P by the first image forming apparatus 1, fixing is performed by the first fixing device 26, and the transparent toner portion is transferred by the second image forming apparatus 2, and then the second fixing device 37. Fixing was carried out. The configuration of Comparative Example 2 corresponds to the configuration of the image forming apparatus disclosed in Patent Document 2.
The first fixing temperature of the first fixing device 26 is 155 ° C.
The second fixing temperature of the second fixing device 37 is 155 ° C.

[Comparative Example 3]
After the colored toner portion 40 is transferred to the paper P by the first image forming apparatus 1, fixing is performed by the first fixing device 26, and the transparent toner portion is transferred by the second image forming apparatus 2, and then the second fixing device 37. Fixing was carried out. The configuration of Comparative Example 3 corresponds to the configuration of the image forming apparatus disclosed in Patent Document 4.
The first fixing temperature of the first fixing device 26 is 155 ° C.
The second fixing temperature of the second fixing device 37 is 170 ° C.

[Example 1]
After the colored toner portion 40 is transferred to the paper P by the first image forming apparatus 1, fixing is performed by the first fixing device 26, and the transparent toner portion is transferred by the second image forming device and then the second fixing device 37. Fixing was performed.
The first fixing temperature of the first fixing device 26 is 155 ° C.
The second fixing temperature of the second fixing device 37 is 150 ° C.

[Example 2]
After the colored toner portion 40 is transferred to the paper P by the first image forming apparatus 1, fixing is performed by the first fixing device 26, and the transparent toner portion is transferred by the second image forming apparatus 2, and then the second fixing device 37. Fixing was carried out.
The first fixing temperature of the first fixing device 26 is 155 ° C.
The second fixing temperature of the second fixing device 37 is 140 ° C.

[Example 3]
After the colored toner portion 40 is transferred to the paper P by the first image forming apparatus 1, fixing is performed by the first fixing device 26, and the transparent toner portion is transferred by the second image forming apparatus 2, and then the second fixing device 37. Fixing was carried out.
The first fixing temperature of the first fixing device 26 is 170 ° C.
The second fixing temperature of the second fixing device 37 is 140 ° C.

  From the results of FIG. 3, it can be seen that in the example in which the second fixing temperature in the second fixing device 37 is lower than the first fixing temperature in the first fixing device 26, a gloss difference can be imparted within the same image. It can be seen that the greater the temperature difference between the first fixing temperature and the second fixing temperature, the greater the difference in gloss between the colored toner portion and the transparent toner portion.

As described above, in the image forming system according to the present embodiment, the colored toner image fixed at the first fixing device 26 at the high first fixing temperature has a high glossiness and the second fixing device 37 has a low second fixing temperature. The transparent toner image fixed in step 1 has a low glossiness, and a gloss difference is given in the same image.
Further, according to the image forming system according to the present embodiment, the temperature of the paper P is detected downstream of the first fixing device 26 in the paper transport direction and upstream of the second fixing device 37 in the paper transport direction. Temperature detecting means is provided. The second fixing device 37 can control the fixing temperature based on the detection result from the temperature detecting means. Thus, in the second fixing device 37, the heat given to the paper P by the first fixing device 26 can be used for the fixing process in the second fixing device 37, and fixing with a smaller amount of heat becomes possible.

  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 process unit 30 of the second image forming apparatus 2, an abnormal image due to paper dust or the like does not occur even when the toner is reused, 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 (4)

A first image forming apparatus having an image forming unit that forms a colored toner image on a recording medium, and a first fixing unit that heat-fixes the colored toner image on the recording medium;
A second image forming unit configured to continuously form a transparent toner image on the recording medium output by the first image forming apparatus; and a second fixing unit configured to heat and fix the colored toner image and the transparent toner image on the recording medium. A second image forming apparatus,
In the image forming system in which the second image forming apparatus is optionally mounted on the first image forming apparatus,
An image forming system, wherein a fixing temperature in the second fixing unit is lower than a fixing temperature in the first fixing unit. The image forming system according to claim 1.
A recording medium temperature detecting means for detecting the temperature of the recording medium downstream of the first fixing means in the recording medium moving direction and upstream of the second fixing means in the recording medium moving direction;
The image forming system, wherein the second fixing unit controls a fixing temperature based on a detection result from the recording medium temperature detecting unit. The image forming system according to claim 1 or 2,
The image forming system, wherein the second image forming unit includes a toner reuse mechanism for reusing toner discharged at the time of image formation. The image forming system according to claim 1, 2 or 3.
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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