JP2013109314A - Image forming apparatus, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide technology which can easily control fixing temperature and decolorization temperature in an image forming apparatus using decolorable coloring material.SOLUTION: An image forming apparatus comprises; a first image forming part; a first heating part; a second image forming part; and a second heating part. The first image forming part transfers binder resin on a sheet. The first heating part heats the sheet where the binder resin is transferred by the first image forming part at temperature equal to or higher than temperature where the binder resin is fixed on the sheet. The second image forming part transfers image information with pigment, which is decolorized when temperature exceeds first temperature, on the binder resin formed on the sheet heated by the first heating part. The second heating part heats the sheet transferred by the second image forming part at temperature lower than the first temperature.

Description

  The embodiment described in this specification relates to a technique for fixing a decoloring toner to a sheet.

  There is a microcapsule pigment that contains an electron-donating color-forming organic compound, an electron-accepting compound, and a temperature-sensitive color-changing color memory composition, and this pigment becomes colorless when heated to a certain degree.

  In addition, an image forming apparatus that prints on a sheet such as paper using a toner (hereinafter referred to as a decoloring toner) in which such a pigment and a resin having a binding action are mixed, or a sheet printed with a decoloring toner There is also a decoloring device that heats the plate at a high temperature to erase the image and reuse the sheet.

  An image forming apparatus using a decoloring toner forms image information on a sheet by heating and fixing at a temperature that does not decolorize. When the sheet is used up, the decoloring device erases image information on the sheet by heating at a temperature at which the pigment decolorizes. Thereby, sheet consumption can be reduced and energy consumption can be reduced.

  The following documents are disclosed as related techniques.

JP 2009-309991 A

  The color development temperature of a microcapsule pigment (hereinafter simply referred to as pigment particles) that changes between colored and colorless by a combination of an electron-donating color-forming organic compound, an electron-accepting compound, and a temperature-sensitive color-changing color memory composition is as follows: In order to allow the recorded information formed above to be stored at room temperature, it is desirable that it be lower than the lowest temperature that can occur in a normal living space, for example, minus 10 ° C. The high temperature decolorization temperature of the pigment particles needs to be sufficiently higher than the temperature at which the resin particles having the binding action are fixed, but at present, the color is decolored at around 100 ° C. or below 100 ° C. There are many.

  On the other hand, resin particles having a binding action (hereinafter simply referred to as binding particles) should not be fused at the highest temperature at which they may be exposed in unused storage or transportation environments, for example, plus 50 ° C. is necessary. The thermoplastic polymer used as the binder particles is fused when stored at an environmental temperature exceeding the glass transition point, and is not fixed unless the temperature becomes higher and the viscosity of the binder particles falls below a certain value. It is desirable that the glass transition point is around 50 ° C., and if it exceeds that, the characteristic that the viscosity decreases at a stretch is desirable. However, in reality, there is a gap of several tens of degrees between the glass transition point and the fixing temperature.

  From the above, it is necessary to control the fixing device at a temperature of about 70 ° C. to 90 ° C. in order to mix the pigment particles and the binder particles and fix them without erasing in one fixing device. It is necessary to precisely control the fixing temperature.

  However, in order to reduce the standby power, rise time, and operation power consumption of the image forming apparatus to a low and low level, recent fixing devices have been developed to reduce the heat capacity by reducing the thickness. For this reason, it is very difficult to keep the temperature control width within ± 10 ° C. due to temperature ripple in order to continuously feed a narrow sheet.

  The exemplary embodiments have been made to solve the above-described problems, and provide a technique capable of easily controlling the fixing temperature and the color erasing temperature in an image forming apparatus using a color erasable color material. The purpose is to do.

  The image forming apparatus includes a first image forming unit, a first heating unit, a second image forming unit, and a second heating unit. The first image forming unit transfers the binder resin to the sheet. The first heating unit heats the sheet on which the binder resin has been transferred by the first image forming unit at a temperature equal to or higher than the temperature at which the binder resin is fixed to the sheet. The second image forming unit transfers the image information with a pigment that decolors when the temperature exceeds the first temperature on the binder resin formed on the sheet heated by the first heating unit. The second heating unit heats the sheet transferred by the second image forming unit at a temperature lower than the first temperature.

1 is a schematic diagram illustrating a configuration example of an image forming apparatus according to a first embodiment. It is a schematic diagram which shows the example of a state transition on the sheet | seat of embodiment. 5 is a flowchart illustrating an operation example of the image forming apparatus of the embodiment. FIG. 6 is a schematic diagram illustrating a configuration example of an image forming apparatus according to a second embodiment.

  The image forming apparatus according to the embodiment forms the above-described colored and colorless pigment particles and the colorless binder particles for fixing the pigment particles on the sheet individually and in different patterns on the sheet. The image forming apparatus according to the embodiment includes an image forming unit corresponding to each of the pigment particles and the binder particles, and also includes a fixing device (heating source) corresponding to each. That is, the image forming apparatus of the embodiment has two sets of image forming units and fixing devices in one apparatus. The image forming apparatus according to the embodiment also has a function of an erasing device that erases information formed on the sheet.

  In the image forming apparatus of the embodiment, first, the binding particles are attached to the sheet by the first image forming unit, and the binding particles attached by the first fixing device are fixed to the sheet. In the embodiment, the first image forming unit adheres the binding particles in a solid form within a range where the image forming apparatus can form an image, such as 70% to 100% of the sheet surface. The heat generation temperature of the first fixing device is a temperature at which the pigment particles can be erased. When an image is already formed on the sheet with the pigment particles, the image can be erased.

  The image forming apparatus according to the embodiment forms image information formed into pigment particles on a sheet processed by the first image forming unit and the first fixing unit by using the second image forming unit. The second image forming unit forms pigment particles on the layer of binder particles fixed on the sheet. Next, the second fixing device heats the sheet at a temperature at which the pigment particles are fixed on the binder particle layer without decoloring, that is, a temperature lower than that of the first fixing device.

  In the above description, the binding particles are attached in a uniform form on the sheet surface.For example, when forming a single line on the sheet, the binding particles are attached so that the line is slightly thicker than the line width. An implementation in which a line of pigment particles is formed on the surface where the binder particles are attached may be used. That is, the binding particles are not uniformly adhered to the sheet surface, but the binding particles may be formed at least in the region including the pigment particle forming region. Thus, by controlling the adhesion region of the binder particles to the minimum, the amount of the binder particles to be used can be reduced as compared with the case where the binder particles are uniformly adhered to the sheet surface.

  The pigment particles of the embodiment are pigment particles that are encapsulated in a combination of an electron-donating color-forming organic compound, an electron-accepting compound, and a temperature-sensitive color-changing color memory composition that are adjusted so as to be colored and colorless. It is a particle having a volume average particle diameter of 5 μm. The pigment particles develop a blue color at room temperature and have the property of being decolored and maintained in a decolored state when heated to 90 ° C. or higher. In the embodiment, 2.5 parts by weight of silica is mixed with 100 parts by weight of the pigment particles and sufficiently stirred to uniformly adhere the silica particles to the surface of the pigment particles. Further, 7 parts by weight of the particles and 93 parts by weight of carrier particles coated with acrylic resin on the ferrite surface having a volume average particle size of 40 μm are mixed so that the average charge amount of the pigment particles becomes −25 uC / g. To do. This developer is referred to as developer A as necessary.

  On the other hand, the binder particles of the embodiment are produced by removing particles containing at least a binder resin and a release agent from a pigment. In the binder particles of the embodiment, 1.5 parts by weight of silica and 0.5 parts by weight of titanium oxide are mixed with 100 parts by weight of the particles and sufficiently stirred, so that these inorganic fine particles are uniformly attached to the resin particle surface. And are produced as binder particles having a volume average particle size of 10 μm. 10 parts by weight of the binder particles and 90 parts by weight of carrier particles coated with an acrylic resin on the ferrite surface having a volume average particle size of 40 μm are mixed and charged with an average charge amount of −28 μC / g. This developer is referred to as developer B as necessary.

  Conventionally, colored resin particles obtained by incorporating pigment particles into a binder resin and coalescing them are put into one image forming unit. However, in the embodiment, these are manufactured as separate particles, and are separated into separate image forming units. throw into. In addition, about the specification and structure of the said pigment particle and binder particle | grain, it is an example to the last, and is not limited to this.

  Hereinafter, each embodiment in view of the above matters will be described with reference to the drawings.

(First embodiment)
A configuration example of the image forming apparatus of the first embodiment is shown in FIG. The image forming apparatus 100 includes a first image forming unit 51 (first image forming unit), a first fixing unit 52 (first heating unit), a second image forming unit 53 (second image forming unit), and a second fixing unit. 54 (second heating unit). The image forming apparatus 100 includes a sheet feeding tray 1 that is a sheet supply source and a sheet discharge tray 8 that is a sheet discharge destination, and conveys the sheet to each unit from the sheet supply tray 1 to the discharge tray 8. It has a transport unit 2.

  The image forming apparatus 100 includes a control board 800 (control unit) that performs overall control of each unit and hardware in the apparatus. The control board 800 includes a processor 801 that is an arithmetic processing unit such as a CPU (Central Processing Unit) and an MPU (Micro Processing Unit), a memory 802 including a volatile storage device and a nonvolatile storage device. The memory 802 stores image information formed on the sheet, various programs, and control data. The processor 801 performs various processes by calculating and executing a program stored in advance in the memory 802.

  The first image forming unit 51 includes a first photoconductor 11 that is an image carrier that rotates in the direction of an arrow, and a first charger 12 that charges the first photoconductor 11. The first image forming unit 51 includes a first exposure device 13 that forms an electrostatic latent image on the charged first photoconductor 11, and the first image forming unit 51 is configured according to the electrostatic latent image formed by the first exposure device 13. A first developing unit 14 for attaching an image (binding particles) on the photoconductor 11 is provided. The first image forming unit 51 includes a first transfer roller 15 that transfers an image on the first photoconductor 11 formed by the first developing device 14 onto a conveyed sheet.

  The first developer 14 is charged with the developer B described above. Therefore, the image forming particles are formed on the sheet by the first image forming unit 51.

  The first fixing device 52 is constituted by the heating roller 4 and the fixing roller 3, and the binder particles transferred onto the sheet are melted to form a layered form by heating the sheet. The surface temperature of the heating roller 4 is 135 ° C. ± 15 ° C., and the binder particles are heated and pressed onto the sheet by the fixing roller 3 and the heating roller 4. The fixing roller 3 is formed by coating a SUS (stainless steel) φ10 mm round bar with a silicon rubber layer having a thickness of 2 mm and further forming a PFA layer with a thickness of 30 μm (PFA: perfluoroalkoxyalkane). The heating roller 4 is a 1 mm thick aluminum tube covered with a PTFE layer 30 μm thick (PTFE: polytetrafluoroethylene), and a heater lamp with a power consumption of 500 W is installed therein. These fixing nips are 5 mm.

  The second image forming unit 53 has the same configuration as that of the first image forming unit 51, and includes a second photoconductor 21, a second charger 22, and a second exposure device 23, and a second developing device 24, a second exposure device 23, and the like. Two transfer rollers 25 are provided. Developer A is charged into the second developing device 24. Therefore, pigment particles are formed on the sheet by the second image forming unit 53.

  The second fixing device 54 includes the heating roller 7 and the fixing roller 6, and fixes the developer A transferred onto the sheet by thermocompression bonding to the sheet. The surface temperature of the heating roller 7 is 75 ° C. ± 15 ° C. The fixing roller 6 is a SUS rod surface of φ8 mm covered with a 1 mm thick silicon rubber layer, and a PFA layer of 30 μm thick is formed on the upper layer. The heating roller 7 is a 1 mm thick aluminum tube with a PTFE layer of 30 μm thick. A heater lamp with a power consumption of 300 W is installed and a fixing nip is 3 mm. The sheet fixed by the second fixing device 54 is discharged to the discharge tray 8.

  The heating roller 4 and the heating roller 7 exchange heat with each other using the fixing belt 5 as a heat transfer medium. Thereby, heating efficiency is improved by utilizing mutual heat generation. A mounting without the fixing belt 5 may be used. Further, the fixing belt 5 is temporarily rotated away from the sheet conveyance path by the rollers 201A and 201B so that the heat of the heating roller 4 is not transmitted to the second image forming unit 53.

  In this example, since it is sufficient that the binder particles can be attached to the sheet surface almost uniformly, it is not necessary to form them according to the image information. Therefore, in this example, the first charger 12 and the first exposure device 13 may be omitted. In this case, the magnitude of the developing bias supplied to the developing roller of the first developing device 14 is adjusted and controlled (define in advance how much binder particles are supplied and transferred onto the sheet, Set it). Note that, when the binder particles are supplied so as to form an image as described above, not the sheet surface, it is necessary to form the binder particles according to the image information. Therefore, in this case, the adhesion area of the binder particles is controlled by the first charger 12 and the first exposure unit 13.

  Also, when reusing a sheet that has been used with the binder resin almost uniformly attached to the sheet surface once or more, since the binder particle layer is already formed on the sheet, the binder particles are attached again. There is no need. The image forming apparatus 100 performs such control using the sensor 61 and the perforator 71. The perforator 71 is a device that opens a hole at a margin portion designated position of a conveyed sheet. Due to this perforation, a history of use / non-use can be left on the sheet. The sensor 61 is a sensor that detects whether or not a hole opened by the puncher 71 is in a specified position in the sheet supplied from the paper feed tray 1. In this embodiment, a transmission type optical sensor is employed. The When the sensor 61 detects that there is a hole, the first image forming unit 51 does not perform the binding particle adhesion process according to the control of the control board 800. For example, if the designated position is set to the front side of the front end of the sheet and the rear side of the rear end of the sheet, there is no hole in the designated position when the sheet is reused upside down. A resin layer is formed.

  The state transition on the sheet will be described with reference to FIG. The sheets stacked on the sheet feeding tray 1 are conveyed to the first image forming unit 51 along the path of the conveying unit 2. To the conveyed sheet, colorless binder particles (developer B) are supplied from the first developing device 14 of the first image forming unit 51 (the left diagram in FIG. 2A). At this time, binder particles in such an amount that 70% or more of the sheet surface is covered are formed on the sheet. Thereafter, the sheet is conveyed to the first fixing device 52 and is heat-pressed by the heating roller 4 and the fixing roller 3 at 135 ° C. ± 15 ° C. As a result, the binder particles melt and become a layered state on the sheet (the right diagram in FIG. 2A).

  The sheet with the binder particle layer is conveyed to the second image forming unit 53, and the colored pigment particles are supplied from the second developing unit 24 onto the second photosensitive member 21, whereby the image information is transferred onto the sheet. (Left view of FIG. 2B). At this time, it is transferred onto the binder particle layer. Thereafter, the sheet is conveyed to the second fixing device 54 and is heat-pressed at 75 ° C. ± 15 ° C. by the heating roller 7 and the fixing roller 6. Thereby, the pigment particles are taken into the binder particle layer, and a visible image is formed on the sheet (the right diagram in FIG. 2B). Thereafter, the sheet is conveyed to the discharge tray 8.

  When the sheet on which the image is thus formed is used up, the image forming apparatus 100 can erase the image on the sheet and print it again. When there is a usage history hole in a sheet fed from the sheet feeding tray 1, the control board 800 performs control so that the first forming unit 51 does not operate. Therefore, in the case of the reuse sheet, the binder particles are not supplied (the left diagram in FIG. 2C).

  The first fixing device 52, which is the next conveyance destination, decolors the image formed on the sheet by heating the used sheet (the right diagram in FIG. 2C). Since the first fixing device 52 is heated at a temperature of 135 ° C. ± 15 ° C. that exceeds the temperature at which the pigment particles are decolored (around 90 ° C. to 100 ° C.), the image formed on the sheet is erased.

  Then, new image information is transferred to the sheet from which the image has been erased by the second image forming unit 53 (the left figure in FIG. 2D), and the second fixing unit 54 has image information on the already existing binder particle layer. Is fixed (the right diagram in FIG. 2D). Since the fixing temperature at this time is lower than the temperature (about 90 ° C. to 100 ° C.) at which the pigment particles are 75 ° C. ± 15 ° C., the image currently transferred to the sheet is not erased.

  Next, an operation example of the image forming apparatus 100 will be described with reference to FIG.

  The sheets stacked on the paper feed tray 1 are supplied into the main body of the image forming apparatus 100 by the transport unit 2 (ACT 101).

  The sensor 61 detects whether the supplied sheet has a predetermined hole, and if there is a hole, outputs a signal to the control board 800. The control board 800 determines the presence / absence of a sheet use history based on the presence / absence of a signal from the sensor 61 (ACT102). When there is a usage history (ACT 102, Yes), the control board 800 controls the first image forming unit 51 not to operate. The sheet is conveyed to the first fixing device 52 as it is, and is heated and decolored by the fixing roller 3 and the heating roller 4 at a temperature equal to or higher than the temperature at which the pigment particles are decolored (135 ° C. ± 15 ° C.) (ACT 105B). Thereafter, the operation transits to the operation of ACT 106.

  On the other hand, when there is no predetermined hole and no use history (ACT 102, No), the first exposure unit 13 of the first image forming unit 51 follows the instruction from the control board 800 on the charged first photoconductor 11. Full-solid (solid) or pattern (image information) is written (ACT 103). The first developing device 14 causes developer B (binder particles) to adhere to the first photoconductor 11, and the first transfer roller 15 uses the image of the binder particles adhering to the first photoconductor 11 as a sheet. Transfer (ACT104). Thereafter, the sheet conveyed to the first fixing device 52 is heated at a temperature (the same temperature as ACT 105B in this example) at which the binder particles are melted and fixed on the sheet (ACT 105A).

  The second exposure unit 23 of the second image forming unit 53 writes image information on the charged second photosensitive member 21 (ACT 106). The second developing device 24 causes developer A (pigment particles) to adhere to the second photoconductor 21, and the second transfer roller 25 transfers the pigment particles of the second photoconductor 21 onto the binder particle layer of the sheet. (ACT107). Thereafter, the sheet is conveyed to the second fixing device 54 and heated at 75 ° C. ± 15 ° C. by the fixing roller 6 and the heating roller 7 (ACT 108). As a result, the pigment particles are fixed on the sheet.

  After that, if the sheet is at least a new sheet (ACT102, if it is determined No), the punching unit 71 punches a hole in the sheet margin. It should be noted that the punching operation may always be performed without determining whether the sheet is a new sheet.

  By adopting such a configuration, it is possible to perform decoloring and fixing of binder particles with one fixing device (first fixing device 52), and it is not necessary to prepare a decoloring device separately. Further, adjustment and control due to the temperature difference between the decoloring temperature and the fixing temperature are not necessary.

  Further, in this embodiment, the pigment particles are not directly fixed on the sheet surface having a non-uniform surface, but are fixed on the binder particle layer smoothed to some extent. As a result, temperature unevenness caused by roughness (unevenness) on the sheet surface can be reduced, so that fixing can be performed at a lower temperature. In addition, it is possible to reduce the possibility that the pigment particles are decolored simultaneously with the fixing by the second fixing device 54.

  Further, since the first fixing device 52 and the second fixing device 54 are arranged side by side in one apparatus, the sheet immediately before entering the second fixing device 54 has a high temperature obtained by the first fixing device 52. To some extent. Therefore, since the amount of temperature rise can be reduced as compared with the case where the pigment particles are fixed to a sheet at room temperature, the fixing can be performed at a lower temperature and in a shorter time. Thereby, energy can be saved as compared with the case where the erasing apparatus and the image forming apparatus are provided separately.

  As a determination of the sheet usage history, a button that allows the user to specify that a sheet to be fed is a reused sheet may be arranged on a control panel (not shown). In this case, the control board 800 controls the operation of the image forming unit 51 according to the pressed button. In addition, when multiple paper feed trays are provided, a tray that only stacks new sheets with no usage history and a tray that stacks sheets with usage history are specified, and new sheets are fed from the stacked tray The mounting may be such that the binder particles are not developed and transferred when the binder particles are developed and transferred and fed from a tray on which sheets having a history of use are stacked.

  The recording of the use history due to perforation is not limited to immediately before the discharge, but may be performed any time from the detection process of the sensor 61 to the discharge. Further, the usage history recording method is not limited to the above-described hole making. A method of cutting a corner portion of the sheet may be used, and a paper pattern of the sheet may be stored in the memory 802 together with the number of times of use and may be managed. In this case, the sensor 61 is a CCD image sensor or the like. There are various implementations for recording usage history.

(Second Embodiment)
In the second embodiment, a mounting example in which pigment particles are attached to a sheet via an intermediate transfer belt will be described. FIG. 4 is a diagram illustrating an image forming apparatus according to the second embodiment.

  The image forming apparatus 200 includes an intermediate transfer belt 26 and a third transfer roller 27 in addition to the image forming apparatus 100 described in the first embodiment, and the second transfer roller 25 and the second photoconductor 21. The transfer belt 26 is positioned between the two.

  Image information developed on the second photosensitive member 21 is primarily transferred to the intermediate transfer belt 26 by the second transfer roller 25. The primary transfer image on the intermediate transfer belt 26 is secondarily transferred onto the sheet by the third transfer roller 27 in the belt rotation direction. In the arrangement configuration, the rotation direction of the second photosensitive member 21 is opposite to that of the first embodiment, so that the arrangement of the second charger 22, the second exposure device 23, and the second developing device 24 is also reversed. Become.

  In the second embodiment, a configuration in which there is no fixing belt 5 (see FIG. 1) that is a heat transfer medium between the heating roller 4 and the heating roller 7 is shown, but the fixing belt 5 may be provided. In the first embodiment, the fixing belt 5 is once rotated between the heating roller 4 and the heating roller 7 so as to be separated from the sheet conveyance path so that the heat of the heating roller 4 is not transmitted to the second image forming unit 53. Yes. In the case of such a configuration, the configuration of the fixing belt and the sheet conveyance path are complicated. On the other hand, when the configuration having the fixing belt 5 is applied to the configuration in which the image is transferred via the intermediate transfer belt 26 as in the second embodiment, the heat of the heating roller 4 propagated by the fixing belt 5 is directly second. There is no transmission to the forming unit 52. Therefore, it is not necessary to separate the fixing belt 5.

  Such a configuration that performs primary transfer and secondary transfer using the intermediate transfer belt is also applicable to the first image forming unit 51.

  In each of the first and second embodiments, the first image forming unit 51 that transfers the binder resin to the sheet, the sheet on which the binder resin is transferred by the first image forming unit 51, and the binder resin as the sheet. On the first fixing device 52 heated at a temperature equal to or higher than the fixing temperature (as an example, 135 ° C. ± 15 ° C.) and the binder resin formed on the sheet heated by the first fixing device 52, the first fixing device 52 The second image forming unit 53 for transferring image information with a pigment that decolors when the temperature exceeds (for example, 90 ° C. to 100 ° C.), and the sheet transferred by the second image forming unit 53 from the first temperature The image forming apparatus 100 having the second fixing device 54 that heats at a lower temperature (as an example, 75 ° C. ± 15 ° C.) has been described.

  With such a configuration, the first fixing device 52 may be adjusted in temperature so that the temperature becomes equal to or higher than the temperature at which the binder resin is melted and fixed on the sheet, and the second fixing device 54 is turned off. The temperature may be adjusted so as to be lower than the color temperature. This makes it easier to control the temperature adjustment than maintaining the conventional fixing device temperature at about 70 ° C. to 90 ° C.

  Further, the temperature of the first fixing device 52 is adjusted to be higher than the temperature at which the pigment particles are decolored (first temperature) and equal to or higher than the temperature at which the binder resin is melted and fixed. Thus, erasing and fixing can be performed with a single heat source. As a result, erasing of the image on the sheet and image formation on the sheet after erasing can be performed within one image forming apparatus, and can be performed without the user's effort.

  On the other hand, in the second fixing device 54, fixing on a surface that is relatively smoothed with a resin layer that has been fixed in advance is fixed at a lower temperature and in a shorter time than directly fixing on a sheet having rough surface properties. Can do. Therefore, the temperature of the second fixing device 54 can be set to a low temperature that does not cause the pigment particles to be decolored.

  In addition, since the two fixing devices continuously pass the sheet, the heating time required to raise the temperature of the normal temperature sheet to the fixing temperature can be shortened. Therefore, it is not necessary to increase the fixing nip of the fixing device more than necessary.

  By adopting the configuration described in the first and second embodiments, a rewritable recycle image formation that is compact and easy to control the fixing temperature and the color erasing temperature as compared with the configuration in which the image forming device and the color erasing device are prepared respectively. A device can be obtained.

  As described in detail above, in the image forming apparatus using the color erasable material, it is possible to easily control the fixing temperature and the color erasing temperature.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the scope of claims, and is not restricted by the text of the specification. Further, all modifications, various improvements, alternatives and modifications belonging to the equivalent scope of the claims are all within the scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 Paper feed tray, 2 Conveying part, 3 Fixing roller, 4 Heating roller, 5 Fixing belt, 6 Fixing roller, 7 Heating roller, 8 Ejection tray, 11 1st photoreceptor, 12 1st charger, 13 1st exposure device , 14 1st developing device, 15 1st transfer roller, 21 2nd photoconductor, 22 2nd charger, 23 2nd exposure device, 24 2nd developing device, 25 2nd transfer roller, 26 Intermediate transfer belt, 27 1st 3 transfer roller, 51 first image forming unit, 52 first fixing device, 53 second image forming unit, 54 second fixing device, 61 sensor, 71 perforator, 100, 200 image forming apparatus, 800 control board, 801 Processor, 802 memory.

Claims (10)

A first image forming unit for transferring the binder resin to the sheet;
A first heating unit that heats the sheet on which the binder resin has been transferred by the first image forming unit at a temperature equal to or higher than a temperature at which the binder resin is fixed to the sheet;
A second image forming unit that transfers image information with a pigment that decolors when exceeding a first temperature on the binder resin formed on the sheet heated by the first heating unit;
A second heating unit that heats the sheet transferred by the second image forming unit at a temperature lower than the first temperature;
An image forming apparatus. The image forming apparatus according to claim 1.
The first heating unit heats the sheet at a temperature higher than the first temperature. The image forming apparatus according to claim 2, further comprising:
An image forming apparatus comprising: a control unit that controls at least the operation of the first image forming unit and controls the first image forming unit not to operate when there is a use history indicating that the sheet has been used once or more. The image forming apparatus according to claim 3, further comprising:
A history adding unit for forming a usage history in a predetermined format on the sheet;
A detection unit for detecting whether the use history by the history adding unit is formed on the sheet,
The control unit controls the first image forming unit so as not to operate when the detection unit detects that the use history is not formed on the sheet. The image forming apparatus according to any one of claims 1 to 4, wherein:
The first image forming unit is an image forming apparatus that uniformly transfers a binder resin to an image forming region on a sheet surface. The image forming apparatus according to any one of claims 1 to 4, wherein:
The first image forming unit is an image forming apparatus that transfers a binder resin in a pattern of the image information. The image forming apparatus according to any one of claims 1 to 6,
An image forming apparatus comprising: a heat transfer unit that transfers heat generated by the first heating unit and the second heating unit. The image forming apparatus
Transfer the binder resin to the sheet,
Heating the sheet to which the binder resin has been transferred at a temperature equal to or higher than the temperature at which the binder resin is fixed to the sheet;
On the binder resin formed on the heated sheet, image information is transferred with a pigment that decolors when the first temperature is exceeded,
An image forming method in which the sheet on which the pigment has been transferred is heated at a temperature lower than the first temperature. The image forming method according to claim 8.
The image forming apparatus, wherein the image forming apparatus heats the sheet at a temperature higher than the first temperature when the binder resin is heated at a temperature equal to or higher than a temperature at which the binder resin is fixed to the sheet. The image forming method according to claim 9.
The image forming apparatus performs transfer of the binder resin to the sheet when there is no use history indicating that the sheet has been used once or more. When the sheet has the use history, the image forming apparatus transfers the binder resin to the sheet. An image forming method without transferring.

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