JP2016161702A - Image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of displacement of the positions of images on a continuous sheet compared with a case where fixing temperatures in a plurality of image forming apparatuses are set to the same temperature.SOLUTION: An image forming system comprises: first and second image forming apparatuses 2 and 3 that are arranged along a direction of conveyance of a continuous sheet 6 and form images on the continuous sheet 6; and first and second fixing devices 40and 40that are provided in the first and second image forming apparatuses 2 and 3, respectively, and fix images transferred onto the continuous sheet 6. A fixing temperature Tof the first image forming apparatus 2 located on the upstream side along the direction of conveyance of the continuous sheet 6, is set lower than a fixing temperature Tof the second image forming apparatus 3 located on the downstream side.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming system.

  Conventionally, as a technique related to an image forming system, for example, those described in Patent Documents 1 and 2 have already been proposed.

  Patent Document 1 discloses a first printing device that prints on continuous paper, a second printing device that prints on continuous paper after printing by the first printing device, and printing by the first printing device. And a synchronization means for synchronizing with the printing by the second printing apparatus.

  Patent Document 2 discloses an image forming system in which a plurality of image forming apparatuses are arranged in series and an image is formed on a sheet by the plurality of image forming apparatuses, and the first image forming apparatus and the first image forming apparatus. And a second image forming apparatus disposed downstream in the sheet conveyance direction. The first image forming apparatus includes a first image forming unit that forms an image on a sheet, a first image forming apparatus, When the second image forming apparatus performs serial tandem output in which images are formed and fixed on different sides of the sheet and printed on both sides, the first fixing temperature of the first fixing unit is determined by the first image forming apparatus alone. The image forming apparatus includes a first control unit that is set lower than a first basic temperature that is a fixing target temperature for image formation and fixing.

JP 2011-198174 A JP 2012-108273 A

  An object of the present invention is to suppress the occurrence of misalignment between a plurality of image forming apparatuses in an image on a continuous sheet as compared with a case where fixing temperatures in a plurality of image forming apparatuses are set to the same temperature. And

The invention described in claim 1 is arranged along the conveying direction of the continuous sheet, and a plurality of image forming apparatuses that form an image on the continuous sheet;
Fixing means provided on each of the plurality of image forming apparatuses and fixing the image transferred onto the continuous sheet, the fixing temperature of the image forming apparatus positioned on the upstream side in the conveyance direction of the continuous sheet A plurality of fixing means set lower than the fixing temperature of the image forming apparatus located downstream,
An image forming system comprising:

  According to a second aspect of the present invention, the fixing temperature of the image forming apparatus positioned upstream in the conveyance direction of the continuous sheet is 5 to 50 ° C. than the fixing temperature of the image forming apparatus positioned downstream. 2. The image forming system according to claim 1, wherein the image forming system is low.

According to a third aspect of the present invention, the plurality of image forming apparatuses include a first image forming apparatus that forms yellow, magenta, cyan, and black images, and a specific color other than the yellow, magenta, cyan, and black. A second image forming apparatus for forming the image of
3. The image forming system according to claim 1, wherein the second image forming apparatus is disposed on an upstream side in a conveyance direction of the continuous sheet.

According to a fourth aspect of the present invention, there is provided switching means for switching which of the plurality of image forming apparatuses is positioned on the upstream side in the conveyance direction of the continuous sheet.
A setting for setting a fixing temperature of the image forming apparatus located on the upstream side in the conveyance direction of the continuous sheet to be lower than a fixing temperature of the image forming apparatus located on the downstream side according to a switching result of the switching unit. Means,
The image forming system according to claim 1, further comprising:

  According to a fifth aspect of the present invention, there is provided a retention portion that temporarily retains the continuous sheet conveyed from the upstream image forming apparatus to the downstream image forming apparatus between the plurality of image forming apparatuses. The image forming system according to claim 1, wherein the image forming system is an image forming system.

  The invention described in claim 6 is the image forming system according to claim 5, wherein the conveyance of the continuous sheet in the upstream image forming apparatus is stopped first.

  According to a seventh aspect of the present invention, in the image forming system according to the fifth aspect, the conveyance of the continuous sheet in the image forming apparatus on the upstream side is started first.

  According to the first aspect of the present invention, compared to the case where the fixing temperatures of the plurality of image forming apparatuses are set to the same temperature, the image on the continuous sheet is misaligned between the plurality of image forming apparatuses. It can be suppressed from occurring.

  According to the second aspect of the present invention, the difference in fixing temperature between the image forming apparatus located on the upstream side and the image forming apparatus located on the downstream side in the conveying direction of the continuous sheet is less than 5 ° C. or 50 ° C. Compared with the case where the value is set to exceed the value, it is possible to suppress the positional deviation between the plurality of image forming apparatuses in the image on the continuous sheet.

  According to the third aspect of the present invention, the first image forming apparatus that forms yellow, magenta, cyan, and black images is disposed on the upstream side in the continuous sheet conveyance direction. It is possible to improve the fixability of images of specific colors other than yellow, magenta, cyan and black.

  According to the invention described in claim 4, it is compared with the case where no switching means for switching which image forming apparatus is located upstream in the conveyance direction of the continuous sheet among the plurality of image forming apparatuses is provided. Thus, the degree of freedom of installation of the plurality of image forming apparatuses can be improved.

  According to the fifth aspect of the present invention, it is possible to reduce the loss of the continuous sheet as compared with the case where the staying part for temporarily retaining the continuous sheet is not provided.

  According to the sixth aspect of the present invention, it is possible to reduce the loss of the continuous sheet as compared with the case where the conveyance of the continuous sheet in the upstream image forming apparatus is not stopped first.

  According to the seventh aspect of the present invention, it is possible to reduce the time required for image formation as compared with the case where the conveyance of the continuous sheet in the upstream image forming apparatus is not started first.

1 is an overall configuration diagram showing an image forming system according to Embodiment 1 of the present invention. 1 is a configuration diagram illustrating an image forming unit of an image forming apparatus according to Embodiment 1 of the present invention; 1 is a configuration diagram illustrating an image forming unit of an image forming apparatus according to Embodiment 1 of the present invention; It is a section lineblock diagram showing a continuous sheet. It is a block diagram which shows the control apparatus of an image forming system. FIG. 3 is a cross-sectional configuration diagram illustrating a fixing device. FIG. 3 is a schematic cross-sectional view showing a fixing belt. FIG. 3 is a partially broken plan view showing the fixing device. FIG. 3 is a cross-sectional configuration diagram illustrating a fixing device. It is a graph which shows the contraction rate of the continuous sheet after passing the nip part of a fixing device. 3 is a graph showing fixing temperatures of first and second fixing devices. It is a whole block diagram which shows the image forming system which concerns on Embodiment 2 of this invention. It is a whole block diagram which shows the image forming system which concerns on Embodiment 3 of this invention. 10 is a timing chart illustrating an operation of a fixing device in an image forming system according to Embodiment 3 of the present invention. It is a whole block diagram which shows the image forming system which concerns on Embodiment 4 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1]
1 to 3 show an image forming system according to the first embodiment. FIG. 1 shows an outline of the entire image forming system, and FIGS. 2 and 3 show enlarged main parts (image forming apparatus and the like) in the image forming system.

<Overall configuration of image forming system>
The image forming system 1 according to Embodiment 1 includes a plurality (two in the illustrated example) of first and second sheets along the conveyance direction of a continuous sheet 6 that is a continuous long continuous form medium as an example of a recording medium. This is a multiplex system in which the second image forming apparatuses 2 and 3 are arranged in series. In the first and second image forming apparatuses 2 and 3, the first image forming apparatus 2 is disposed on the upstream side and the second image forming apparatus 3 is disposed on the downstream side along the conveyance direction of the continuous sheet 6. . As the continuous sheet 6, those made of various materials are used. The material of the continuous sheet 6 includes not only plain paper, but also so-called label paper in which release paper is attached to one side of plain paper or a synthetic resin film via an adhesive, or a synthetic resin film or sheet. Can be mentioned. The continuous sheet 6 has at least one of the longitudinal direction that is the conveying direction or the width direction that intersects the conveying direction at the time of heating and fixing, or the longitudinal direction, depending on the material and a pretreatment such as a stretching process that has been performed on the continuous sheet 6 in advance. Some have the property of deforming (mainly shrinking) in both the direction and the width direction.

  The image forming system 1 includes a first image forming apparatus 2, a second image forming apparatus 3, a supply apparatus 4 that supplies a continuous sheet 6 as an example of a recording medium, and first and second image forming apparatuses. 2 and 3 is disposed between the first image forming apparatus 2 and the second image forming apparatus 3 for collecting (accommodating) the continuous sheet 6 on which an image has been formed and conveys the continuous sheet 6. And a control device 100 for controlling the first and second image forming apparatuses 2 and 3. The control apparatus 100 is directly connected to the first and second image forming apparatuses 2 and 3 or the first and second image via a communication line 7 such as a LAN (Local Area Network) or the Internet. The forming apparatuses 2 and 3 and the host apparatus 8 including a personal computer are connected so as to be able to communicate with each other. In the illustrated example of the image forming system 1, the first and second image forming apparatuses 2 and 3, the supply apparatus 4, the collection apparatus 5, and the control apparatus 100 are separately configured. However, the present invention is not limited to this. For example, the supply device 4 is inside the first image forming device 2, the collecting device 5 is inside the second image forming device 3, and the control device 100 is first or You may arrange | position in the upper part of the 2nd image forming apparatuses 2 and 3 etc.

  The first and second image forming apparatuses 2 and 3 have basically the same configuration except for the color of the image to be formed. As shown in FIGS. 1 and 2, the second image forming apparatus 3 is configured as a color printer that forms yellow (Y), magenta (M), cyan (C), and black (K) images, for example. It has been done. On the other hand, as shown in FIGS. 1 and 3, the first image forming apparatus 2 has yellow (Y), magenta (M), cyan (C) and black (black) used in a normal color printer. Other than K), for example, it is configured as a printer of a specific color that forms an image of a specific color (also referred to as a special color) such as white (W), transparent (T), gold (G), and silver (S). . The first image forming apparatus 2 may form an image of a color other than a specific color such as white (W), transparent (T), gold (G), and silver (S). The specific color is not limited to white (W), transparent (T), gold (G), and silver (S), but may be a metal color other than gold (G) or silver (S), or It may contain foamed toner.

The first image forming apparatus 2 forms an image on the continuous sheet 6 using toner of four colors of white (W), transparent (T), gold (G), and silver (S) based on the image data. and a first image forming unit 106 ₁ by an electrophotographic system as an example of a forming unit. The second image forming apparatus 3 forms an image on the continuous sheet 6 using toners of four colors of yellow (Y), magenta (M), cyan (C) and black (K) based on the image data. and a electrophotographic method according to the second image forming unit 106 ₂ as an example of an image forming unit that. For example, the host device 8 generates image data using full colors and specific colors of white (W), transparent (T), gold (G), and silver (S). The first and second image forming units 106 ₁ and 106 ₂ are formed by a plurality of image forming apparatuses 10 that form toner images developed with toner constituting the developer 4 and the respective image forming apparatuses 10. The intermediate transfer device 20 that holds the toner images to be transferred to the secondary transfer position where the toner images are finally transferred to the continuous sheet 6, and the toner images on the continuous sheet 6 that are secondarily transferred by the intermediate transfer device 20. A fixing device 40 for fixing is provided.

  For example, the image forming system 1 can be configured as a color copying machine when an image reading device as an image reading unit (not shown) for inputting a document image to be formed on the continuous sheet 6 is additionally provided. . Reference numerals 2a and 3a in the figure indicate the housings of the first and second image forming apparatuses 2 and 3, and the housings 2a and 3a are formed of a support structure member, an exterior cover, and the like.

    The image forming apparatus 10 of the first image forming apparatus 2 includes four image forming apparatuses that individually form four color toner images of white (W), transparent (T), gold (G), and silver (S). It is composed of 10W, 10T, 10G, and 10S. Here, white (W) is used as the first specific color, transparent (T) is used as the second specific color, gold (G) is used as the third specific color, and silver (S) is used as the fourth specific color. Each is used. These four image forming devices 10 (W, T, G, S) are arranged in a line in the internal space of the housing 1a.

  On the other hand, the image forming apparatus 10 of the second image forming apparatus 3 has four image forming units for forming toner images of four colors of yellow (Y), magenta (M), cyan (C), and black (K). The image devices 10Y, 10M, 10C, and 10K are configured. These four image forming devices 10 (Y, M, C, K) are also arranged in a line in the internal space of the housing 1a.

  As shown in FIGS. 2 and 3, each image forming device 10 includes a photosensitive drum 11 as an example of a rotating image holding member. The device is mainly arranged. The main devices are a charging device 12 that charges a peripheral surface (image holding surface) on the photosensitive drum 11 on which an image can be formed to a required potential, and image information (on the charged peripheral surface of the photosensitive drum 11). The exposure device 13 as an electrostatic latent image forming means for forming an electrostatic latent image (for each color) having a potential difference by irradiating the light LB based on the signal), and a developer of the corresponding color on the electrostatic latent image A developing device 14 as a developing unit that develops the toner image with toner, a primary transfer device 15 that transfers each toner image to the intermediate transfer device 20, and an image holding surface of the photosensitive drum 11 after the primary transfer. A drum cleaning device 16 or the like that removes and removes adhering matter such as toner that remains and adheres.

  The photosensitive drum 11 is formed by forming an image holding surface having a photoconductive layer (photosensitive layer) made of a photosensitive material on the peripheral surface of a cylindrical or columnar base material to be grounded. The photosensitive drum 11 is supported so as to rotate in a direction indicated by an arrow A when power is transmitted from a rotation driving device (not shown).

  The charging device 12 includes a contact-type charging roll that is disposed in contact with the photosensitive drum 11. A charging voltage is supplied to the charging device 12. As the charging voltage, when the developing device 14 performs reversal development, a voltage or current having the same polarity as the charging polarity of the toner supplied from the developing device 14 is supplied.

  The exposure device 13 forms an electrostatic latent image by irradiating the charged surface of the photosensitive drum 11 with light LB configured according to image information input to the image forming device 1. To do. When the latent image is formed, the exposure device 13 receives information (signal) of an image input to the image forming devices 2 and 3 by an arbitrary means and subjected to image processing by the image processing unit. As the exposure device 13, the photosensitive drum 11 is irradiated with light according to image information by LEDs (Light Emitting Diodes) as a plurality of light emitting elements arranged along the axial direction of the photosensitive drum 11, and statically exposed. An LED print head that forms an electrostatic latent image may be used.

  Each of the developing devices 14 has a developing roll 141 that holds the developer 4 and conveys it to a developing area facing the photosensitive drum 11 in a housing 140 in which an opening and a storage chamber for the developer 4 are formed. Layer thickness that regulates the amount (layer thickness) of the developer 4 held on the developing roll 141 and the stirring and conveying members 142 and 143 such as two screw augers that convey the developer 4 to be supplied to the developing roll while stirring. The restriction member 144 and the like are arranged. A developing bias voltage is supplied to the developing device 14 between the developing roll 141 and the photosensitive drum 11 from a power supply device (not shown). Further, the developing roll 141 and the agitating / conveying members 142 and 143 are rotated in a required direction by receiving power from a rotation driving device (not shown). As the developer 4, for example, a two-component developer containing a non-magnetic toner and a magnetic carrier is used.

  In FIG. 1, reference numeral 145 denotes a toner cartridge as a developer storage container that stores a developer containing at least toner to be supplied to the corresponding developing device 14. In this embodiment, only toner is contained in the toner cartridge 145.

  The primary transfer device 15 is a contact-type transfer device including a primary transfer roll that rotates in contact with the peripheral surface of the photosensitive drum 11 and is supplied with a primary transfer voltage. As the primary transfer voltage, a DC voltage having a polarity opposite to the charging polarity of the toner is supplied from a power supply device (not shown).

  The drum cleaning device 16 is disposed so as to contact the peripheral surface of the photosensitive drum 11 after the primary transfer with a container-shaped main body 160 that is partially opened, and removes adherents such as residual toner. A cleaning plate 161 for cleaning, a collection device 162 for collecting the deposits removed by the cleaning plate 161, and the like are included.

  As shown in FIGS. 1 to 3, the intermediate transfer device 20 is disposed so as to exist at a position above each image forming device 10 (Y, M, C, K). The intermediate transfer device 20 includes an intermediate transfer belt 21 that rotates in a direction indicated by an arrow B while passing a primary transfer position between the photosensitive drum 11 and the primary transfer device 15 (primary transfer roll), and an intermediate transfer belt 21. Are arranged on the outer peripheral surface (image holding surface) side of the intermediate transfer belt 21 supported by the belt support rolls 23 and a plurality of belt support rolls 22 to 26 that hold the belt in a desired state from the inner surface thereof and are rotatably supported. A secondary transfer device 30 for secondary transfer of the toner image on the intermediate transfer belt 21 to the recording paper 5, and a toner that remains and adheres to the outer peripheral surface of the intermediate transfer belt 21 after passing through the secondary transfer device 30; The belt cleaning device 27 mainly removes the adhering matter such as paper dust and cleans it.

  As the intermediate transfer belt 21, for example, an endless belt made of a material in which a resistance adjusting agent such as carbon black is dispersed in a synthetic resin such as polyimide resin or polyamide resin is used. The belt support roll 22 is configured as a drive roll, the belt support roll 23 is configured as a secondary transfer backup roll, the belt support roll 24 is configured as a tension applying roll, and the belt support rolls 25 and 26 are intermediate transfer belts. It is comprised as a driven roll holding 21 running positions.

  As shown in FIG. 1, the secondary transfer device 30 is configured to move the intermediate transfer belt 21 at a secondary transfer position that is an outer peripheral surface portion of the intermediate transfer belt 21 supported by the belt support roll 23 in the intermediate transfer device 20. It is a contact type transfer device provided with a secondary transfer roll that rotates in contact with a peripheral surface and is supplied with a secondary transfer voltage. Further, a DC voltage having a polarity opposite to or opposite to the charging polarity of the toner is supplied as a secondary transfer voltage to the secondary transfer roll 30 or the support roll 23 of the intermediate transfer device 20.

  The fixing device 40 is in contact with a rotating rotator 41 in the form of a roll or belt heated by heating means so that the surface temperature is maintained at a predetermined temperature, and the rotating rotator 41 for heating at a required pressure. And a pressurizing rotator 42 in the form of a roll or a belt that rotates. In the fixing device 40, a contact portion where the heating rotator 41 and the pressing rotator 42 come into contact becomes a fixing processing unit that performs a required fixing process (heating and pressing). The configuration of the fixing device 40 will be described in detail later.

  By the way, the supply device 4 supplies a long continuous sheet 6 as a continuous recording medium. For example, as shown in FIG. 4, the continuous sheet 6 is made of synthetic resin such as PP (polypropylene), paper such as glassine paper or high-quality paper, and generally has a role as a mount and is discarded when used. A so-called label paper is used in which a surface base material 63 provided as an uppermost layer is adhered to a release paper 61 via an adhesive layer 62 made of an adhesive material such as glue as an intermediate layer. The label paper 6 is used after its design and characters are printed on its surface base 63. The label paper 6 is supplied as, for example, roll paper wound in a roll shape so that the surface base material 63 side is positioned on the surface (outer peripheral surface) which is an image forming surface, depending on the application.

  As shown in FIG. 1, the supply device 4 includes a paper feed roll 64 composed of a continuous sheet 6 wound up in a roll shape. The paper feed roll 64 is rotationally driven counterclockwise by a driving unit (not shown) and supplies the continuous sheet 6. Further, a first guide that guides the continuous sheet 6 supplied from the supply device 4 to the secondary transfer position of the first image forming device 2 between the supply device 4 and the first image forming device 2. A roll 65 is arranged.

  Also, the continuous sheet 6 discharged from the first image forming apparatus 2 is supplied to the second image forming apparatus 3 between the first image forming apparatus 2 and the second image forming apparatus 3. A conveying device 9 for conveying is provided. The transport device 9 includes a first transport roll pair 91 disposed above corresponding to the discharge unit of the first image forming apparatus 2 and a second transport disposed below the first transport roll pair 91. And a roll pair 92.

  On the other hand, a second guide roll 66 that guides the continuous sheet 6 conveyed by the conveying device 9 to the secondary transfer position of the second image forming device 3 is disposed below the second image forming device 3. ing. Further, on the side of the second image forming apparatus 3, conveying rolls 67 and 68 for conveying the continuous sheet 6 discharged from the second image forming apparatus 3 to the collecting apparatus 5 are arranged.

  The collection apparatus 5 includes a collection roll 69 that collects the continuous sheet 6 that is discharged from the second image forming apparatus 3 and conveyed by the conveyance rolls 67 and 68 in a roll shape. The collection roll 69 is rotationally driven counterclockwise by a driving unit (not shown), and collects and stores the continuous sheet 6 on which an image is formed.

  FIG. 5 shows a control device that controls the image forming system (first and second image forming apparatuses).

  The control apparatus 100 includes a CPU (Central Processing Unit) 101 that controls the image forming operations of the first and second image forming apparatuses 2 and 3 in an integrated manner. The CPU 101 refers to parameters stored in a RAM (Random Access Memory) 103 based on a program stored in advance in a ROM (Read Only Memory) 102, and images in the first and second image forming apparatuses 2 and 3. Control the forming operation.

Reference numeral 104 a user interface unit for inputting a user to form an image type and size of the continuous sheet 6 or (the number of printed images) the number of prints, etc., 105 an image reading apparatus for reading an image of an original, 106 ₁ , _{106. 2} shows the first and second image forming unit in the first and second image forming apparatuses 2 and 3, respectively.

<Basic operation of image forming system>
Hereinafter, a basic image forming operation by the first and second image forming apparatuses 2 and 3 of the image forming system 1 will be described.

  Here, the four image forming apparatuses 10 (Y, M, C, K) of the second image forming apparatus 3 are used to combine toner images of four colors (Y, M, C, K). An image forming operation when forming a full color image will be described as an example. The four image forming devices 10 (W, T, G, S) of the first image forming device 2 are used, and toner of any one or more of the four colors (W, T, G, S) is used. The image forming operation when forming an image is the same.

  When the second image forming apparatus 3 receives command information for requesting an image forming operation (print) from the control apparatus 100, the second image forming apparatus 3 includes four image forming apparatuses 10 (Y, M, C, K), an intermediate transfer apparatus 20, The next transfer device 30, the fixing device 40, etc. are started.

  In each image forming device 10 (Y, M, C, K), each photoconductor drum 11 is first rotated in the direction indicated by an arrow A, and each charging device 12 makes a required surface of each photoconductor drum 11 on the surface. Each is charged to a polarity (negative polarity in the first embodiment) and a potential. Subsequently, the exposure device 13 converts the image information input to the second image forming device 3 into each color component (Y, M, C, K) on the surface of the photosensitive drum 11 after charging. The light LB emitted based on the obtained image signal is irradiated, and electrostatic latent images of the respective color components each having a required potential difference are formed on the surface thereof.

  Subsequently, each developing device 14 (Y, M, C, K) has a corresponding color charged with a required polarity (minus polarity) with respect to the electrostatic latent image of each color component formed on the photosensitive drum 11. (Y, M, C, K) toners are respectively supplied and electrostatically adhered to perform development. By this development, the electrostatic latent images of the respective color components formed on the respective photosensitive drums 11 are visualized as toner images of four colors (Y, M, C, K) respectively developed with the corresponding color toners. It becomes.

  Subsequently, when each color toner image formed on the photosensitive drum 11 of each image forming device 10 (Y, M, C, K) is conveyed to the primary transfer position, the primary transfer device 15 causes each color image. The toner image is primarily transferred in such a manner that the toner image is sequentially superimposed on the intermediate transfer belt 21 rotating in the direction indicated by the arrow B of the intermediate transfer device 20.

  Further, in each image forming apparatus 10 for which the primary transfer has been completed, the drum cleaning device 16 cleans the surface of the photosensitive drum 11 by removing the adhering matter such as toner remaining on the surface of the photosensitive drum 11 so as to scrape off. . Thereby, each image forming apparatus 10 is brought into a state in which the next image forming operation can be performed.

  Subsequently, in the intermediate transfer device 20, the toner image primarily transferred by the rotation of the intermediate transfer belt 21 is held and conveyed to the secondary transfer position. The continuous sheet 6 is fed and supplied to the secondary transfer position of the intermediate transfer device 20 via the second guide roll 66 in synchronism with the image formed on the continuous sheet 6 by the first image forming device 2. Is done.

  At the secondary transfer position, the secondary transfer device 30 collectively transfers the toner image on the intermediate transfer belt 21 onto the continuous sheet 6 on which the image is formed by the first image forming device 2. Further, in the intermediate transfer device 20 after the secondary transfer is completed, the belt cleaning device 27 removes adhered matters such as toner remaining on the surface of the intermediate transfer belt 21 after the secondary transfer, and cleans it.

  Subsequently, the continuous sheet 6 on which the toner image is secondarily transferred is peeled off from the intermediate transfer belt 21 and the secondary transfer roll 30 and then conveyed to the fixing device 40. In the fixing device 40, necessary fixing processing (heating and pressing) is performed to fix the unfixed toner image on the continuous sheet 6. Finally, the continuous sheet 6 after the fixing is finished is discharged to the outside of the second image forming apparatus 3 and is wound around the collection roll 69 of the collection apparatus 5 via the conveyance rolls 67 and 68.

  With the above operation, the continuous sheet 6 on which a full color image formed by combining four color toner images is output.

  In addition, the four image forming apparatuses 10 (W, T, G, S) of the first image forming apparatus 2 are connected to the second image forming apparatus 3 prior to the image forming operation of the second image forming apparatus 4. Through the same process, a toner image of one or more of four colors (W, T, G, S) is formed on the continuous sheet 6. The continuous sheet 6 is supplied to the first image forming apparatus 2 from the paper supply roll 64 of the supply apparatus 4 via the first guide roll 65. Further, the continuous sheet 6 on which an image has been formed by the first image forming apparatus 2 is conveyed to the second image forming apparatus 4 via a pair of conveying rolls 91 and 92 of the conveying apparatus 9 and a second guide roll 66. Is done.

<Configuration of Characteristic Part of Image Forming Apparatus>
6 together with the first fixing device 40 ₁ which is used for the first image forming apparatus 2 configured as described above, the second fixing device 40 ₂ for use in the second image forming apparatus 3 FIG. The first and second fixing devices 40 ₁ and 40 ₂ are configured similarly.

As shown in FIG. 6, the fixing device 40 includes an unfixed toner image G (on an unfixed toner image G (on a nip portion) N formed between the fixing belt 41 as a heated endless belt and the fixing belt 41. in the case of the second fixing device 40 _2, the pressure roll 42 as a pressurizing rotator that rotates across the continuous sheet 6 holding the toner image fixing already and the unfixed toner image G), the fixing belt 41 A pressing pad 43 as a pressing member for press-contacting the pressing pad 42 to the pressing roll 42 and a support member 44 for supporting the pressing pad 43 are provided.

  The fixing device 40 is disposed opposite to an outer peripheral surface located on the opposite side of the nip portion N of the fixing belt 41 with a predetermined gap therebetween, and generates an alternating magnetic field for electromagnetically heating the fixing belt 41. An alternating magnetic field generator 45, a heat storage member 46 that is disposed in contact with the inside of the fixing belt 41 so as to face the alternating magnetic field generator 45 via the fixing belt 41, and stores heat generated by the fixing belt 41; And a peeling assisting member 47 that assists in peeling the continuous sheet 6 from the fixing belt 41.

  The fixing belt 41 is formed into a thin cylindrical shape having an outer diameter of about 20 to 50 mm before being deformed by being pressed against the pressure roll 42. In this embodiment, the outer diameter of the fixing belt 41 is set to about 30 mm. As shown in FIG. 7, the fixing belt 41 includes, for example, a base layer 411, a heat generation layer 412, an elastic layer 413, and a surface release layer 414 that are sequentially stacked on the outer peripheral surface thereof. However, the fixing belt 41 may be provided with a protective layer on the outer periphery of the heat generating layer 412, and the layer configuration is arbitrary.

  As shown in FIG. 6, the pressure roll 42 is coated with a cored bar member 421 formed in a cylindrical shape with a metal such as stainless steel or aluminum, and a surface of the cored bar member 421 having a predetermined thickness. A heat-resistant elastic body layer 422 made of silicone rubber and the like, and a PFA (copolymer of tetrafluoroethylene and perfluoroalkoxyethylene) coated on the surface of the elastic body layer 422 to a thickness of about 50 μm, for example ) And the like and a release layer 423 made of a material excellent in release properties. The pressure roll 42 is formed in, for example, a solid substantially cylindrical shape having an outer diameter of about 28 mm.

  The material of the pressing pad 43 that presses the fixing belt 41 and the pressure roll 42 is, for example, an elastic body having heat resistance such as silicone rubber or fluorine rubber, and as shown in FIG. It is attached in a state of being fitted in a recess 52 provided at a position facing the pressure roller 42 of 44. The pressing pad 43 is a member that forms a nip portion N between the fixing belt 41 and the pressure roll 42 by being pressed against the pressure roll 42 via the fixing belt 41.

  As shown in FIG. 6, the support member 44 has a rigidity such that the amount of deflection when receiving the pressure contact force from the pressure roll 42 via the pressure pad 43 is equal to or less than a predetermined value. It is formed in a rectangular cross section. The support member 44 is made of a material that does not affect or hardly gives influence to the induction magnetic field. For example, a heat resistant resin such as PPS (polyphenylene sulfide) mixed with glass fiber, a nonmagnetic metal material such as aluminum, or the like is used. Is used.

  Further, as shown in FIG. 8, the fixing device 40 includes a device frame 52 as a frame formed in an elongated rectangular shape. Fixing portions 51 provided at both ends of the support member 44 are fixedly attached to the apparatus frame 52, and a fixing member (not shown) is attached to the outer periphery of the support portion of the support member 44. It is mounted so that it can rotate freely.

  Further, as shown in FIG. 8, both end portions of a drive shaft 53 for rotationally driving the fixing belt 41 are rotatably attached to the apparatus frame 52 via bearing members 54. The drive shaft 53 is attached with driven gears 55 that engage with the drive portions 48 b of the flange members 48 located at both ends of the fixing belt 41 at both ends located inside the apparatus frame 52. In addition, a transmission gear 56 that transmits a driving force to the drive shaft 53 is attached to one end portion of the drive shaft 53 that is located outside the apparatus frame 52, and the transmission gear 56 includes a drive motor 57. A drive gear 59 fixed to the rotary shaft 58 is engaged. The rotation shaft 58 of the drive motor 57 has a base end portion rotatably attached to the device frame 52 of the fixing device 40. The fixing device 40 rotates the drive motor 57 to transmit the rotational drive force of the drive motor 57 to the drive shaft 53 via the drive gear 59 and the transmission gear 56 and is attached to the drive shaft 53. The fixing belt 41 is rotated at a predetermined rotational speed by the driving portions 48b and 48b of the flange member 48 provided at both ends of the fixing belt 41 that rotates the driven gears 55 and 55 and meshes with the driven gears 55 and 55. Driven by rotation.

  As described above, the fixing belt 41 is configured by laminating the base layer 411 made of a metal material or a synthetic resin material, the heat generating layer 412, the elastic layer 413, and the surface release layer 414. It has flexibility and mechanical strength, and even when it receives rotational drive torque from the drive portions 48b and 48b of the flange member 48, buckling or the like does not occur. Smoothly driven to rotate.

  As shown in FIG. 8, both ends of the rotary shaft 425 are rotatably supported by the apparatus frame 52 via the bearing member 70, and the pressure roll 42 is disposed at both ends of the rotary shaft 425. The coil spring 71 serving as the biasing means is pressed against the fixing belt 41 with a predetermined pressing force. In this embodiment, as will be described later, in order to improve the productivity of the fixing device 40, the pressure contact force between the pressure roll 42 and the pressing pad 43 is set higher than in the prior art, and the two coil springs 71. The total load is set to, for example, about 50 to 80 kgf. The bearing member 70 that rotatably supports the pressure roll 42 is held by a long hole (not shown) so as to be movable with respect to the device frame 52 of the fixing device 40 in a direction in which it is in contact with and away from the fixing belt 41.

  The pressure roll 42 can be moved in a direction in which it is pressed against or separated from the fixing belt 41 by a contact / separation mechanism 72, and is configured to separate the pressure roll 42 when heating of the fixing belt 41 is started.

  As a specific configuration of the contact / separation mechanism 72, for example, as shown in FIG. 9, an arm member 73 that rotatably supports both ends of the rotation shaft 425 of the pressure roll 42 is provided. One end portion 73 a of 73 is rotatably supported around a fulcrum 74, and the other end portion 73 b is configured to be pressed in a direction in pressure contact with the fixing belt 41 by a coil spring 71. . Further, an eccentric cam 76 that is rotationally driven by a rotating shaft 75 is disposed above the other end 73b of the arm member 73, and the eccentric cam 76 is rotationally driven at a predetermined timing. The other end 73 b of the arm member 73 is pushed down, and the pressure roll 42 is separated from the fixing belt 41.

  Furthermore, as shown in FIG. 6, an alternating magnetic field generator 45 disposed on the opposite side of the fixing belt 41 from the pressure roll 42 includes, for example, an exciting coil 80 for generating an alternating magnetic field and an exciting coil 80. Of the magnetic path of the alternating magnetic field generated by the holding member 81 that is held in a predetermined position in an arc shape and the exciting coil 80, the magnetic path is formed in a substantially arc shape that forms a magnetic path on the outer peripheral side of the fixing belt 41. An external magnetic path forming member 82 and an excitation circuit 83 that excites the excitation coil 80 by supplying a high-frequency current.

  In addition, as shown in FIG. 6, a heat storage member 84 is disposed inside the fixing belt 41. The heat storage member 84 is a member having a heat storage function that is disposed so as to face the alternating magnetic field generator 45 via the fixing belt 41 and that conducts heat to the fixing belt 41 to compensate for the temperature drop of the fixing belt 41. is there. The heat storage member 84 is a member that forms a magnetic path inside the alternating magnetic field generated by the alternating magnetic field generator 45, and is made of a temperature-sensitive magnetic material whose permeability varies with temperature. A function of controlling the heat generation of the heat generating layer 412 is also provided. The heat storage member 86 is formed in an arc shape that follows the inner peripheral surface of the fixing belt 41, and the central angle of the arc-shaped portion along the inner peripheral surface of the fixing belt 41 is set to about 160 degrees, for example. Is done. The heat generation control member 84 is screwed to the support member 44 via plate-like members 85 attached to both ends thereof.

By the way, in this embodiment, as shown in FIG. 1, in the first image forming apparatus 2, at least one of white (W), transparent (T), gold (G) and silver (S) is used. after transferring the toner image on the continuous sheet 6, and fixed by the fixing device 40 ₁ provided a toner image transferred onto the continuous sheet 6 to the first image forming apparatus 2, and subsequently, a second image In the forming device 3, yellow (Y), magenta (M), cyan (C), and black (K) toner images are transferred onto the continuous sheet 6, and then the toner images transferred onto the continuous sheet 6 are transferred to the second toner image. an image is formed by fixing the image forming apparatus 3 by the fixing device 40 ₂ provided.

At this time, fixable on the first image forming apparatus a continuous sheet 6 a fixing temperature of the fixing device 40 ₁ and the temperature equal to the fixing temperature of the fixing device 40 ₂ in the second image forming apparatus 3 toner image in 2 When the temperature is set to a relatively high temperature (for example, about 185 ° C.), white (W), transparent (T), gold (G), and silver (S) toner images in the first image forming apparatus 2 are used. the when fixed on a continuous sheet 6 by the first fixing device 40 _1, as shown in FIG. 10, the continuous sheet (medium) 6 is contracted by heating in the first fixing device 40 _1. FIG. 10 shows the time elapsed after the continuous sheet 6 passes through the nip N of the _first fixing device 401 as the horizontal axis, the contraction rate generated in the continuous sheet 6 as the vertical axis, the fixing temperature of 135 ° C., 160 The change of the shrinkage rate which arises in the continuous sheet 6 at the time of changing with 185 degreeC is calculated | required. Label paper is used as the continuous sheet 6. The shrinkage rate of the continuous sheet 6 reaches 0.20% when the fixing temperature is 185 ° C. Therefore, the toner image of at least one color of white (W), transparent (T), gold (G), and silver (S) is fixed on the continuous sheet 6 at the fixing temperature of 185 ° C. in the first image forming apparatus 2. In such a case, the continuous sheet 6 contracts by about 0.20%.

  As a result, in the second image forming apparatus 3, yellow (Y), magenta (M), cyan (C), and black (K) toner images are subsequently transferred to white (W), transparent (T), and gold (G ) And silver (S) toner image of at least one color or more is transferred onto the continuous sheet 6 on which the toner image has already been formed. The position of the image formed by the second image forming apparatus 2 is shifted according to the contraction of the continuous sheet 6 with respect to the image formed by the apparatus 2, so that the position of the image is shifted.

Therefore, in this embodiment, the first image forming apparatus low fixing temperature _{T 1} of the fixing device 40 ₁ of the fixing temperature _{T 2} of the fixing device 40 ₂ in the second image forming apparatus 3 in 2 _(T 1 < T ₂₎ by setting, thereby reducing the shrinkage of the continuous sheet 6 caused by the fixing device 40 ₁ in the first image forming apparatus 2 (deformation). Fixing the temperature T ₁ of the fixing device 40 ₁ in the first image forming apparatus 2, varies depending on the material and size, etc. of the continuous sheet 6, the fixing temperature T ₂ of the fixing device 40 ₂ in the second image forming apparatus 3 Set 5 to 50 ° C lower. When the temperature difference between the first and second fixing devices 40 ₁ and 40 ₂ is less than 5 ° C., a sufficient effect of suppressing image displacement on the continuous sheet 6 cannot be obtained, and the temperature difference exceeds 50 ° C. In this case, the fixing temperature T ₁ in the fixing device 40 ₁ of the first image forming apparatus 2 becomes excessively low, and fixing failure such as a low temperature offset occurs in the fixing device 40 ₁ , which is not preferable. The difference of the fixing temperature _{T 1} of the fixing device 40 ₁ and the fixing temperature _{T 2} of the fixing device 40 ₂ in the second image forming apparatus 3 in the first image forming apparatus 2 further to set the 20 to 30 ° C. desirable.

Fixing the temperature T ₁ of the fixing device 40 ₁ in the first image forming apparatus 2, as shown in FIG. 11, it is desirable from the viewpoint of the fixing property of preventing fixing failure such as low-temperature offset is 140 ° C. or higher. Further, the fixing temperature _{T 2} of the fixing device 40 ₂ in the second image forming apparatus 3, yellow (Y), magenta (M), cyan (C) and 160 ° C. From the viewpoint of the color of the black (K) toner It is desirable that In this embodiment, the fixing temperature _{T 1} of the fixing device 40 ₁ in the first image forming apparatus 2 to 140 ° C., respectively the fixing temperature _{T 2} of the fixing device 40 ₂ in the second image forming apparatus 3 to 160 ° C. It is set. Therefore, the temperature difference between the fixing temperature _{T 2} and the fixing temperature _{T 1} of the first fixing device 40 ₁ second fixing device 40 ₂ is 20 ° C..

  White (W), transparent (T), gold (G), and silver (S) specific color toners used in the first image forming apparatus 2 are mixed with toner particles made of synthetic resin in white (W) or gold ( G) or silver (S) or the like to develop a specific color such as a white pigment or a metal powder, and the transparent (T) toner includes normal yellow (Y), magenta ( M), cyan (C), and black (K) toners have a larger particle size than toners, so they are fixed more than yellow (Y), magenta (M), cyan (C), and black (K) toners. It is desirable that fixing is performed at a high temperature, which is originally 180 ° C. or higher.

In this embodiment, are set white (W), transparent (T), gold (G) and the fixing temperature _{T 1} of the specific color toner silver (S) to 140 ° C.. Even in this case, toner images of specific colors of white (W), transparent (T), gold (G), and silver (S) are fixed at 140 ° C. in the fixing device 401 of the _first image forming apparatus 2. subjected to fixing treatment with T _1, toner particles fixability is secured against continuous sheet 6 was melted and softened. In addition, toner images of specific colors of white (W), transparent (T), gold (G), and silver (S) are fixed at a fixing temperature T of 160 ° C. in the fixing device 402 of the _second image forming apparatus 3. ₂ for the second fixing process. Therefore, the toner particles of specific colors of white (W), transparent (T), gold (G), and silver (S) are once melted and softened in the _first fixing device 401, and the continuous sheet 6 itself is also the first. while by being heated by the fixing device 40 ₁ maintains the second image forming apparatus 3 of the secondary transfer is not hindered to the extent of the temperature (preheating), 160 ° C. and a relative in the second fixing device 40 ₂ The second fixing process is performed at a high temperature. Accordingly, white (W), transparent (T), comprising a specific color toner Gold (G) and silver (S) image, first second fixing device 40 ₂ for synergy with the fixing device 40 ₁ Therefore, good fixability can be obtained even at a fixing temperature (140 ° C. and 160 ° C.) lower than the originally desirable fixing temperature of 180 ° C.

The fixing temperatures T ₁ and T ₂ of the fixing devices 40 ₁ and 40 ₂ in the first and second image forming apparatuses 2 and 3 are fixed by the control device 100 by the first and second image forming units 106 ₁ and 106 ₂ . In the devices 40 ₁ and 40 ₂ , the fixing temperature of the fixing belt 41 is 140 ° C., which is the first fixing temperature T ₁ , by changing the frequency and current value of the high-frequency current supplied from the excitation circuit 83 to the excitation coil 80. And the second fixing temperature T ₂ is controlled to be equal to 160 ° C.

<Operation of Characteristic Part of Image Forming Apparatus>
In the first embodiment, when the first and second image forming apparatuses 2 and 3 receive the command information of the request for the image forming operation (printing) from the control apparatus 100, as described above, the first image forming apparatus 2 part 106 ₁ and the second image forming unit 106 ₂ in the four image forming devices 10, an intermediate transfer device 20, the secondary transfer device 30, a fixing device 40 and the like is started.

In the first image forming apparatus 2, after the toner image of at least one color of white (W), transparent (T), gold (G), and silver (S) is transferred onto the continuous sheet 6, by fixing belt 41 and the pressure roll 42 in the fixing device 40 ₁ passes through the nip portion N in pressure contact, white on a continuous sheet 6 (W), transparent (T), gold (G) and silver (S) The toner image of at least one of the above is fixed.

At this time, the fixing temperature _{T 1} of the fixing device 40 ₁ in the first image forming apparatus 2, for example, set to 140 ° C.. Therefore, a toner image of at least one color of white (W), transparent (T), gold (G), and silver (S) fixed on the continuous sheet 6 has a low temperature offset or the like as shown in FIG. Thus, the toner image is fixed on the continuous sheet 6 without causing the fixing failure.

Then, in the second image forming apparatus 3, yellow on a continuous sheet 6 (Y), magenta (M), after the toner image of cyan (C), and black (K) has been transferred, in the fixing device 40 ₂ By passing through the nip portion N where the fixing belt 41 and the pressure roll 42 are in pressure contact, toner images of yellow (Y), magenta (M), cyan (C) and black (K) are fixed on the continuous sheet 6. The At this time, the fixing temperature _{T 2} of the fixing device 40 ₂ in the second image forming apparatus 3, for example, set to 160 ° C.. Therefore, the yellow (Y), magenta (M), cyan (C), and black (K) color toner images fixed on the continuous sheet 6 are in a state of good color development as shown in FIG. It is fixed by. Also, white (W), a specific color toner images of transparent (T), gold (G) and silver (S) is fixability was good, moreover, receiving a second time fixing process by the fixing device 40 ₂ Therefore, the toner image is fixed on the continuous sheet 6 in a stable state.

As described above, in the first embodiment, the fixing temperatures T ₁ and T ₂ in the first and second image forming apparatuses 2 and 3 are set to the same relatively high temperature equal to the conventional fixing temperature. In comparison, as shown in FIG. 10, the shrinkage rate of the continuous sheet 6 after fixing in the first image forming apparatus 2 can be suppressed to a low value of about 0.05%. It is possible to suppress a positional deviation between the image formed by the second image forming apparatus 3.

[Embodiment 2]
FIG. 12 shows an outline of the entire image forming apparatus according to the second embodiment.

  In the second embodiment, as shown in FIG. 12, of the first and second image forming apparatuses 2 and 3, any one of the image forming apparatuses 2 and 3 is upstream along the conveyance direction of the continuous sheet 6. A switching device is provided as an example of switching means for switching between the two positions.

  In the second embodiment, as the switching device, switching transport rolls 93 and 94 additionally provided on the side (right side surface in the drawing) of the first image forming apparatus 2 are provided. Further, as the first guide roll 65 disposed below the first image forming apparatus 2, instead of the guide roll consisting of a single roll, guide rolls 65a and 65b consisting of a pair of rolls are used. ing.

  In the second embodiment, toner images of specific colors of white (W), transparent (T), gold (G), and silver (S) are formed in the lower layer, and yellow (Y) and magenta (M ), When forming cyan (C) and black (K) color toner images, as shown in FIG. 12A, the continuous sheet 6 is fed from the supply device 4 as in the first embodiment. Then, the continuous sheet 6 is guided to the secondary transfer position of the first image forming apparatus 2 through one guide roll 65b of the first guide roll pair 65, and is discharged from the first image forming apparatus 2. The continuous sheet 6 is configured to guide the continuous sheet 6 to the secondary transfer position of the second image forming apparatus 3 via the conveying device 9 and the second guide roll 66. At this time, the transport rollers 93 and 94 for switching are not used.

On the other hand, in the second embodiment, yellow (Y), magenta (M), cyan (C) and black (K) color toner images are formed in the lower layer, and white (W), transparent (T), When a toner image of specific colors of gold (G) and silver (S) is formed thereon, as shown in FIG. 5 is made to function as a supply device, and the continuous sheet 6 is supplied from the collection device 5. Continuous sheet 6 fed from the recovery unit 5 via a second guide roll 66 leads to the secondary transfer position of the second image forming apparatus 3, the continuous sheet has passed through the second fixing device 40 ₂ 6 Is guided to the secondary transfer position of the first image forming apparatus 2 through the other guide roll 65a of the conveying apparatuses 91 and 92 and the first guide roll pair 65, and then the first image forming apparatus 2 is used. The continuous sheet 6 discharged from the sheet is collected by the supply device 4 that functions as a collection device via the switching transport rolls 93 and 94. The supply device 4 is equipped with a collection roll 69.

At this time, the fixing temperature of the fixing device 402 of the _second image forming apparatus 3 located on the upstream side in the conveyance direction of the continuous sheet 6 is adjusted by the control device 100 that also functions as a setting unit. apparatus 2 of the fixing device 40 _first temperature lower than the fixing temperature is set to, for example, 140 ° C.. Further, the fixing temperature of the fixing device 401 of the _first image forming apparatus 2 is set to a temperature higher than the fixing temperature of the fixing device 402 of the _second image forming apparatus 3, for example, 160 ° C.

  The image forming operations in the first and second image forming apparatuses 2 and 3 are controlled by the control device 100 that also functions as a setting unit.

  As described above, in the second embodiment, the first and second image forming apparatuses 2 and 3 are switched by adding the transport rollers 93 and 94 for switching as switching devices and switching the transport path of the continuous sheet 6. Without moving the toner images of specific colors of white (W), transparent (T), gold (G) and silver (S) in the lower layer, or yellow (Y), magenta (M), cyan ( Whether the toner images of C) and black (K) are formed in the lower layer can be switched.

[Embodiment 3]
FIG. 13 shows an overview of the entire image forming apparatus according to the third embodiment.

<Overall Configuration of Image Forming Apparatus>
In the image forming system 1 according to the third embodiment, the first image forming apparatus 2 on the upstream side is connected to the second image forming apparatus 3 on the downstream side between the first and second image forming apparatuses 2 and 3. A staying roll pair for staying is provided as a staying part for staying the continuous sheet 6 being transported temporarily.

  The staying transport roll pair is composed of a transport roll pair 92 located below the transport device 9. Among the pair of rolls of the transport roll pair 92, one transport roll 92b is separated from the other transport roll 92a from the standby position in contact with the other transport roll 92a, as shown in FIG. Thus, it is configured to be movable at a predetermined speed to the separated position moved downward. The transport roll pair 92 is positioned at a standby position where one roll 92b is in contact with the other roll 92a, as shown in FIG. 13B, during standby (standby) before the image forming operation is started. .

  Then, along with the image forming operation in which the first image forming apparatus 2 forms an image on the continuous sheet 6 (synchronously), the direction in which one roll 92b is separated from the other roll 92a as the continuous sheet 6 is conveyed. The image forming apparatus 1 starts moving, stops at a lower stop position in synchronization with the image forming operation started by the second image forming apparatus 3, and conveys the continuous sheet 6 to the second image forming apparatus 3.

  In the image forming system 1 according to the third embodiment, the first and second image forming apparatuses 2 and 3 do not start the image forming operation at the same time. After starting the forming operation, the second image forming apparatus 3 is configured to start the image forming operation.

  Further, in the image forming system 1 according to the third embodiment, the first and second image forming apparatuses 2 and 3 do not stop the image forming operation at the same time, but the first image forming apparatus 2 performs the image first. After the formation operation is stopped, the second image forming apparatus 3 is configured to stop the image formation operation.

In the image forming system 1 according to the third embodiment, as illustrated in FIG. 14, when a print instruction is received from the host device 8, the first image forming apparatus is performed at a timing t 1 synchronized with the reception of the print instruction by the control device 100. fixing device 40 ₁ 2 is started, the fixing belt 41 is heated by an alternating magnetic field generator 45. Next, when it is detected that the surface temperature of the fixing belt 41 exceeds a predetermined first threshold, for example, a temperature equal to the first fixing temperature (140 ° C.), the control device 100 detects the timing t2. in conjunction with the first fixing belt 41 to start the driving motor 57 of the fixing device 40 ₁ is driven to rotate, it is pressed against the pressure roll 42 to the fixing belt 41.

  At this time, in synchronization with the activation of the fixing device 40, the image forming devices 10W, 10T, 10G, and 10S of the first image forming device 2 and the intermediate transfer device 20 are activated, and white (W) is formed on the intermediate transfer belt 21. , Transparent (T), gold (G), and silver (S) specific toner images are transferred onto the continuous sheet 6 and fixed by the first fixing device 40.

Thereafter, in the second image forming apparatus 3, the fixing device 402 of the _second image forming apparatus 3 is activated by the control device 100, and the fixing belt 41 is heated by the alternating magnetic field generator 45. Next, when it is detected that the surface temperature of the fixing belt 41 exceeds a predetermined second threshold value, for example, a temperature equal to the second fixing temperature (160 ° C.), the control device 100 detects the first belt temperature. The second fixing device at timing t3 when the registration (image forming position) of the image formed on the continuous sheet 6 by the image forming apparatus 2 and the image formed on the continuous sheet 6 by the second image forming apparatus 3 match. drives the fixing belt 41 start 40 ₂ of the drive motor 57, is pressed against the pressure roll 42 to the fixing belt 41.

Then, in synchronization with the start of the second fixing device 40 _2, the second image forming apparatus 3 of the image forming apparatus 10Y, 10M, 10C, 10K and the intermediate transfer unit 20 is activated, yellow on the intermediate transfer belt 21 (Y), magenta (M), cyan (C), and black (K) color toner images are transferred.

Next, when the image forming operation in the first image forming apparatus 2 is completed, as shown in FIG. 14, the heating of the fixing belt 41 in the _first fixing apparatus 401 is performed at a timing t4 predetermined by the control apparatus 100. Is stopped, and when it is detected that the temperature of the fixing belt 41 has decreased below the conveyance stop permission temperature (t5), the drive motor 57 is stopped to stop the conveyance state of the fixing belt 41. The pressure contact between the fixing belt 41 and the pressure roll 42 is continued.

As described above, when it is detected that the temperature of the fixing belt 41 has dropped below the conveyance stop permission temperature, the conveyance state of the fixing belt 41 is stopped, so that unnecessary conveyance of the continuous sheet 6 is reduced. At this time, the fixing temperature of the fixing belt 41, up to for relatively low compared to the ₂ second fixing device 40, the temperature of the fixing belt 41 stops conveyance states drop below conveyance stop permission temperature Time is shortened.

Thereafter, the image forming operation in the second image forming apparatus 3 is completed, the heating of the fixing belt 41 in the second fixing device 40 ₂ is stopped at a predetermined timing by the control device 100, the temperature of the fixing belt 41 is When it is detected that the temperature has fallen below the conveyance stop permission temperature (t6), the drive motor 57 is stopped to stop the conveyance state of the fixing belt 41, and at the same time, the pressure contact between the fixing belt 41 and the pressure roll 42 is released. Also, to release the pressure contact of the fixing belt 41 and the pressure roll 42 at the same timing t6 of the first fixing device 40 _1. In the first fixing device 40 ₁ may release the pressure contact of the fixing belt 41 and the pressure roll 42 in early than the timing t6 as described above.

As described above, in the image forming system 1 according to the third embodiment, as shown in FIG. 14, the fixing temperature T of the _first fixing device 401 at the end of the image forming operation in the first image forming device 2. _{since 1} is set lower than the fixing temperature T ₂ of the second fixing device 40 _2, the time until the temperature of the first fixing device 40 ₁ of the fixing belt 41 is lowered below the conveying stop permission temperature shortened , it is possible to stop the conveyance state of the fixing belt 41 in the first fixing device 40 ₁ early. Therefore, it is possible to shorten the time until stopping the fixing belt 41 in the first fixing device 40 ₁ of the first image forming apparatus 2, a continuous sheet that is wastefully conveyed between the fixing belt 41 until it is stopped The amount of 6 decreases.

  At that time, the continuous sheet 6 after the fixing belt 41 is stopped in the first image forming apparatus 2 is transported to the second image forming apparatus 3 by the continuous sheet 6 retained on the staying transport roller pair 92. Therefore, there is no problem in image formation on the continuous sheet 6 in the second image forming apparatus 3.

  At the start of image formation, the continuous sheet 6 on which an image has been previously formed in the first image forming apparatus 2 is retained on a staying conveyance roll pair 92, and an image forming operation is performed in the second image forming apparatus 3. When started, the movement of one roll 92 b of the staying transport roll pair 92 is stopped and transported to the second image forming apparatus 3.

[Embodiment 4]
FIG. 15 shows an outline of the entire image forming apparatus according to the fourth embodiment.

<Overall Configuration of Image Forming Apparatus>
As in the first embodiment, the image forming system 1 according to the fourth embodiment forms an image using toner of specific colors of white (W), transparent (T), gold (G), and silver (S). The first image forming apparatus 2 and the second image forming apparatus 3 that forms an image using toner of four colors of yellow (Y), magenta (M), cyan (C), and black (K). Although the configuration of the image forming unit of the first and second image forming apparatuses 2 and 3 is different from that of the first embodiment, the configuration of the feeding device and the conveying device of the continuous sheet 6 is also corresponding thereto. Is different.

  In the fourth embodiment, as shown in FIG. 15, in the first and second image forming apparatuses 2 and 3, four image forming apparatuses 10 (Y, M, C, K) are provided on the intermediate transfer belt 21. The secondary transfer roll that is disposed above and that transfers the toner image transferred onto the intermediate transfer belt 21 to the continuous sheet 6 is the lowest position in the movement path of the intermediate transfer belt 21. 30 is arranged.

Continuous sheet 6 is fed from the feeder 4 which is disposed upstream of the first image forming apparatus 2, after passing the secondary transfer portion of the first image forming apparatus 2 and the fixing device 40 _1, the second To the image forming apparatus 3. Between the first image forming apparatus 2 and the second image forming apparatus 3, a staying roll 91 made up of three rolls is disposed for retaining the continuous sheet 6. Among the three staying rolls 91, the roll 91b located in the middle is movable toward a lower position away from the two rolls 91a and 91c located at the other end portions.

Continuous sheet 6 conveyed to the second image forming apparatus 3, after passing through the secondary transfer portion of the second image forming apparatus 3 and the fixing unit 40 _2, the second image forming apparatus 3 on the downstream side (the side The paper is wound around the collecting device 5 through a pair of discharge rolls 67 arranged in the direction).

  In the fourth embodiment, as shown in FIG. 15, the conveyance path of the continuous sheet 6 can be configured in a substantially straight line, and the occurrence of damaged paper on the continuous sheet 6 is further reduced.

  In the above embodiment, the image forming system including the first image forming apparatus 2 and the second image forming apparatus 3 has been described. However, the number of image forming apparatuses is limited to two. Instead, three or more units may be provided.

1 ... image forming system, 2 ... first image forming apparatus, 3 ... second image forming apparatus, 6 ... continuous sheet, 40 1 _... first fixing device, 40 2 _... second fixing device.

Claims (7)

A plurality of image forming apparatuses which are arranged along a conveying direction of the continuous sheet and form an image on the continuous sheet;
Fixing means provided on each of the plurality of image forming apparatuses and fixing the image transferred onto the continuous sheet, the fixing temperature of the image forming apparatus positioned on the upstream side in the conveyance direction of the continuous sheet A plurality of fixing means set lower than the fixing temperature of the image forming apparatus located downstream,
An image forming system comprising:   2. The fixing temperature of the image forming apparatus located on the upstream side in the conveying direction of the continuous sheet is 5 to 50 ° C. lower than the fixing temperature of the image forming apparatus located on the downstream side. The image forming system described. The plurality of image forming apparatuses include a first image forming apparatus that forms yellow, magenta, cyan, and black images, and a second image forming that forms images of specific colors other than the yellow, magenta, cyan, and black. With the device,
3. The image forming system according to claim 1, wherein the second image forming apparatus is disposed on an upstream side in a conveyance direction of the continuous sheet. Switching means for switching which image forming apparatus is located upstream of the plurality of image forming apparatuses along the conveyance direction of the continuous sheet;
A setting for setting a fixing temperature of the image forming apparatus located on the upstream side in the conveyance direction of the continuous sheet to be lower than a fixing temperature of the image forming apparatus located on the downstream side according to a switching result of the switching unit. Means,
The image forming system according to claim 1, further comprising:   2. A retention unit that temporarily retains the continuous sheet conveyed from the upstream image forming apparatus to the downstream image forming apparatus is provided between the plurality of image forming apparatuses. 5. The image forming system according to any one of 4 above.   6. The image forming system according to claim 5, wherein conveyance of the continuous sheet in the image forming apparatus on the upstream side is stopped first.   6. The image forming system according to claim 5, wherein the conveyance of the continuous sheet in the upstream image forming apparatus is started first.

Images