JP2011095515A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device which prevents the occurrence of a jam caused by sticking of the recording medium to the application member, in a system in which a foamy fixing liquid for softening resin-containing fine particles is applied to a recording medium by an application member and the resin-containing particles are fixed to the recording medium, and to provide an image forming apparatus having the same. <P>SOLUTION: The fixing device includes: a foamy fixing liquid-generating unit using, as a foamy fixing liquid F, a fixing liquid 132 containing a softener for softening toner; an application roller 141 for applying the foamy fixing liquid F supplied to a surface performing surface movement to the surface of transfer paper P carrying an unfixed toner image T, wherein the fixing device applies a foaming fixing liquid F to transfer paper P in an application nip C, thereby fixing a toner image T to transfer paper. The fixing device includes a heating device 120 for heating the foaming fixing liquid F on the surface of the application roller 141 located downstream in the direction of the surface movement with respect to the upstream end of the application nip C where the foamy fixing liquid F starts contact with the transfer paper P. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and a fixing device applicable to the image forming apparatus. Specifically, a fixing liquid that dissolves or swells at least a part of the resin component of resin-containing fine particles such as toner and fixes the toner on the fixing medium is applied to the resin-containing fine particle layer on the fixing medium or the resin-containing fine particle support. The present invention relates to a fixing device and an image forming apparatus including the same.

  Image forming apparatuses such as printers, facsimile machines, and copying machines are apparatuses that form images including characters and symbols on recording media such as paper, cloth, and OHP sheets based on image information. There are various types of image forming apparatuses. Electrophotographic image forming apparatuses are widely used in offices because they can form high-definition images on plain paper at high speed. In such an electrophotographic image forming apparatus, the toner on the recording medium is heated and softened or melted, and the toner is fixed on the recording medium by pressurizing the softened toner. Fixing devices are widely used. This thermal fixing method is preferably used because it can provide a high fixing speed and high fixed image quality.

However, more than half of the power consumption in the electrophotographic image forming apparatus adopting such a heat fixing method is consumed for heat treatment in the heat fixing type fixing device. On the other hand, from the viewpoint of measures against environmental problems in recent years, an image forming apparatus with low power consumption (energy saving) is desired. For this reason, there is a demand for energy saving in the fixing device that consumes more than half of the power consumption in the conventional image forming apparatus. The conventional heat fixing type fixing device consumes a lot of electric power for the heat treatment, so the fixing method for heating the toner to fix the toner is extremely lower than before, or the toner is heated. A fixing method that does not require this is desired. In particular, a non-heat fixing method in which toner is fixed on a recording medium without heating the toner is ideal in terms of low power consumption.
In such a non-heat fixing type fixing device, a fixing solution containing a softening agent that softens the toner by dissolving or swelling at least a part of the resin component of the toner is applied to the toner image on the surface of the recording medium. A fixing device of a wet fixing type that fixes a toner image is known. In such a wet fixing type fixing device, heat treatment is not required to soften the toner, and energy saving can be realized as compared with the thermal fixing method.

However, in the conventional wet fixing type fixing device, the liquid fixing solution is applied to the surface of the recording medium by the application member, and a small amount of the fixing solution is applied to the surface of the recording medium and the toner offset to the application member is prevented. There was a problem that it was extremely difficult to achieve both.
In the configuration in which the fixing solution is applied using the coating member, in the configuration in which a large amount of the fixing solution is applied, the image quality deteriorates due to the toner particles flowing on the recording medium, and the fixing responsiveness increases due to the longer drying time of the fixing solution. There arises a problem that paper jam easily occurs depending on the recording medium and the recording medium.
On the other hand, when a small amount of fixing solution is applied, the following problems occur. That is, the toner particles on the recording medium are pulled by the surface tension of the liquid film of the fixing solution that is not applied to the recording medium and remains on the surface of the coating member at a position where the coating member comes into contact with the recording medium and then separates from the recording medium. Will be offset. As a result, offset toner particles adhere to the surface of the coating member, and the toner image on the recording medium after separation from the coating member is greatly disturbed.

  As a fixing method capable of satisfying both the application of a small amount of fixing solution and the prevention of toner offset, Patent Document 1 discloses that a fixing solution is used as a foam fixing solution in which bubbles are dispersed in the liquid, and the foam fixing solution is used as a recording medium. A configuration for application to the upper toner image is described. Thus, the bulk density of the fixing solution can be lowered by making the fixing solution foam. For this reason, the film thickness of the fixing liquid on the surface of the coating member can be increased with a smaller amount of fixing liquid than before, and the influence of the surface tension of the liquid on the toner particles on the fixing liquid application target can be reduced. As a result, toner offset can be prevented. Further, since the amount of the fixing solution is small, it is possible to suppress the residual liquid feeling on the recording medium. Further, since the foam-like fixing solution is less likely to flow than a normal liquid fixing solution, it is possible to prevent image deterioration caused by the toner particles on the fixing solution application target being caused to flow by the fixing solution. Therefore, by performing fixing using a foamy fixing solution as in the fixing device described in Patent Document 1, it is possible to fix the toner image without disturbing with a smaller amount of fixing solution applied than before.

In the configuration in which the fixing liquid is applied to the recording medium using the application member, the recording medium that has passed the application position for applying the fixing liquid is separated from the application member and conveyed toward the outside of the apparatus.
However, when the foam fixing solution is applied to the recording medium using the coating member, the foam fixing solution carried on the coating member comes into contact with the recording medium, so that the foam fixing solution is separated from the recording medium by the adhesive force of the bubbles. There is a possibility that the recording medium adheres to both surfaces of the coating member and the recording medium sticks to the coating member via the foamy fixing solution, resulting in poor separation and jamming.

  The present invention has been made in view of the above problems, and its object is to apply a foam-like fixing solution for softening resin-containing fine particles to a recording medium by an application member and fix the resin-containing fine particles to the recording medium. Another object of the present invention is to provide a fixing device capable of preventing the occurrence of a jam caused by the recording medium sticking to the coating member, and an image forming apparatus including the fixing device.

In order to achieve the above object, the invention of claim 1 is a foam in which bubbles are dispersed in a fixing solution containing a softening agent that softens resin-containing fine particles by dissolving or swelling at least part of the resin. Fixing solution foaming means as a fixing solution, and a coating member for applying the foamed fixing solution supplied to the surface moving surface to the surface of a recording medium carrying a resin-containing fine particle layer made of the resin-containing fine particles. A fixing device for fixing the resin-containing fine particle layer softened by applying the foamy fixing solution on the surface of the coating member to the recording medium at a coating position; Has heating means for heating the foamy fixing solution on the surface of the coating member on the downstream side in the surface movement direction with respect to the position where the recording medium starts to be contacted.
According to a second aspect of the present invention, there is provided the fixing device according to the first aspect, further comprising an opposing member that forms an application nip by contacting the application member with the recording medium sandwiched at the application position. The foam-like fixing solution on the surface of the coating member on the downstream side in the surface movement direction of the coating member with respect to the center of the coating nip is heated.
According to a third aspect of the present invention, in the fixing device according to the first or second aspect, the heating means heats the foamy fixing solution on the surface of the coating member by heating the surface of the coating member. To do.
According to a fourth aspect of the present invention, there is provided the fixing device according to any one of the first to third aspects, wherein the fixing device is located on a conveyance path of the recording medium upstream of the coating position in the conveyance direction of the recording medium. Detecting means for detecting the leading end of the recording medium, and only when the vicinity of the leading end of the recording medium passes through the area heated by the heating means when the leading end of the recording medium is detected by the detecting means. The heating means has control means for controlling to perform heating.
According to a fifth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects, the foam-like fixing solution on the surface is heated by the heating means, and then the foam-like shape is passed. It has a cooling means for cooling the surface of the coating member before reaching the position where the fixing solution is supplied.
According to a sixth aspect of the present invention, there is provided a toner image forming means for forming a toner image on a recording medium using a toner containing resin-containing fine particles containing a resin and a colorant, and a toner image transferred to the recording medium. An image forming apparatus comprising: a fixing unit that applies a foamy fixing liquid to a surface of a recording medium to fix the toner image on the recording medium, wherein the fixing unit is any one of claims 1 to 5. The fixing device described in item 1 is used.

In the configuration in which the present inventors apply a foam fixing solution to a recording medium with an application member, bubbles on the surface of the application member on the downstream side in the surface movement direction with respect to the position at which the foam fixing solution starts to contact the recording medium. When the fixing solution was heated, it was confirmed that the separation property of the recording medium with respect to the coating member was improved. This is thought to be due to the following reasons.
That is, by heating by the heating means, bubbles of the foam-like fixing solution on the surface of the coating member on the downstream side in the surface movement direction with respect to the position where the foam-like fixing solution starts to contact the recording medium are broken. The bubbles of the foam-like fixing solution on the surface of the coating member break up, so that the fixing solution forming the foamed bubbles becomes liquid, part of which adheres to the surface of the coating member and the other part Adheres to the recording medium or the foamy fixing solution on the recording medium. The bubbles of the foam-like fixing solution are broken to become liquid, and a gas layer is formed in the space where the foamed bubbles are present by the gas forming the bubbles in the foam-like fixing solution. By forming a gas layer between the application member and the recording medium, it is considered that the recording medium attached to the application member via the foamy fixing solution can be separated from the application member.
In addition, the present inventors have configured to start heating the foamy fixing solution on the surface of the coating member from the upstream side in the surface movement direction with respect to the position where the foamy fixing solution starts to contact the recording medium ( In Comparative Example 3) described later, it was confirmed that toner offset occurred and the image was disturbed. This is similar to the configuration in which the liquid fixer is applied when the foam fixer on the surface of the coating member on the upstream side in the surface movement direction is heated with respect to the position where the foamy fixer starts to contact the recording medium. This is presumably because the advantages of using the above-mentioned foamy fixing solution cannot be obtained. Therefore, the heating means of the present invention heats the foam-like fixing solution on the surface of the coating member on the downstream side in the surface movement direction with respect to the position where the foam-like fixing solution starts to contact the recording medium.

  In the present invention, since the separation between the coating member and the recording medium can be improved, there is an excellent effect that jamming due to the recording medium sticking to the coating member can be prevented.

FIG. 3 is an enlarged explanatory diagram of a paper separation mechanism of the fixing device according to the embodiment. 1 is a schematic configuration diagram showing a copier according to an embodiment. FIG. 2 is an enlarged explanatory view of a part of an internal configuration of a printer unit in the copier. FIG. 2 is an enlarged configuration diagram showing one of image forming units of the copier. FIG. 2 is an enlarged configuration diagram illustrating a fixing device of the printer. FIG. 3 is an enlarged configuration diagram illustrating a fixing liquid supply unit of the fixing device. FIG. 3 is an enlarged schematic diagram illustrating a film thickness adjusting blade and a coating roller in the fixing device. FIG. 8 is an enlarged schematic diagram illustrating a film thickness adjusting blade and a coating roller in a state where the film thickness adjusting gap is wider than that in FIG. 7. FIG. 9 is an enlarged configuration diagram illustrating a modified fixing device. FIG. 6 is an explanatory diagram of a printer unit of another example of an image forming apparatus in which a fixing device to which the present invention is applied can be arranged.

Hereinafter, an embodiment of an electrophotographic color copying machine (hereinafter simply referred to as a copying machine 100) will be described as an image forming apparatus to which the present invention is applied. In the present embodiment, the configuration in which the image forming apparatus having the fixing device of the present invention is a copying machine will be described. However, other image forming apparatuses such as a printer and a facsimile may be used.
First, a basic configuration of the copying machine 100 according to the embodiment will be described. FIG. 2 is a schematic configuration diagram illustrating the copying machine 100 according to the embodiment. The copying machine 100 includes a printer unit 1, a paper feeding device 40, and a document conveyance reading unit 50. The document conveyance reading unit 50 includes a scanner unit 150 that is a document reading device fixed on the printer unit 1 and an ADF 51 that is a document conveyance device supported by the scanner unit 150.
FIG. 3 is a partially enlarged configuration diagram illustrating a part of the internal configuration of the printer unit 1 in an enlarged manner.

  The paper feeding device 40 separates and feeds two paper feeding cassettes 42 arranged in multiple stages in the paper bank 41, a feed roller 43 that feeds the transfer paper P from the paper feeding cassette 42, and the fed transfer paper P. A separation roller 45 supplied to the path 44 is provided. Further, a plurality of transport rollers 46 for transporting the transfer paper P to the paper transport path 37 of the printer unit 1 are also provided. Then, the transfer paper P in the paper feed cassette 42 is fed into the paper transport path 37 in the printer unit 1.

  The scanner unit 150 fixed on the printer unit 1 has a fixed reading unit 151 and a moving reading unit 152 as reading means for reading an image of the document MS. A fixed reading unit 151 having a light source, a reflection mirror, an image reading sensor such as a CCD, etc. is disposed immediately below a first contact glass (not shown) fixed to the upper wall of the casing of the scanner unit 150 so as to contact the document MS. ing. When the document MS conveyed by the ADF 51 passes over the first contact glass, the image reading sensor 153 receives the light from the light source through the plurality of reflection mirrors while sequentially reflecting the light emitted from the light source on the document surface. . Thereby, the document MS is scanned without moving the optical system including the light source and the reflection mirror.

On the other hand, the moving reading unit 152 is disposed directly below a second contact glass (not shown) fixed to the upper wall of the casing of the scanner unit 150 so as to come into contact with the document MS, and is arranged on the right side of the fixed reading unit 151 in the drawing. Therefore, an optical system including a light source and a reflection mirror can be moved in the left-right direction in the figure. Then, in the process of moving the optical system from the left side to the right side in the figure, the light emitted from the light source is reflected by a document (not shown) placed on the second contact glass and then passed through a plurality of reflecting mirrors. The light is received by an image reading sensor 153 fixed to the scanner body. Thereby, the original MS is scanned while moving the optical system.
In this way, the scanner unit 150 scans the document MS and, based on the image information obtained by the image reading sensor 153, the optical writing device 2 drives the light source, as will be described later, to form four drum-shaped photoconductors. The laser beam L is irradiated toward 4 (Y, M, C, K).

  The printer unit 1 includes an optical writing device 2, four image forming units 3 (Y, M, C, K) that form toner images of respective colors Y, M, C, and K, a transfer unit 20, and a paper transport unit 28. , A registration roller pair 15, a fixing device 30, and the like. Then, a light source such as a laser diode or LED (not shown) disposed in the optical writing device 2 is driven, and the laser light L is directed toward the four drum-shaped photoconductors 4 (Y, M, C, K). Irradiate. By this irradiation, an electrostatic latent image is formed on the surface of the photoreceptor 4 (Y, M, C, K), which is a latent image carrier, and this latent image is developed into a toner image via a predetermined development process. Is done. The subscripts Y, M, C, and K added after the reference numerals indicate the specifications for yellow, magenta, cyan, and black. The toner corresponding to each color is made of a resin material colored in each color, and these resin materials are dissolved or swollen by a fixing solution of the fixing device 30 described later.

  Each of the image forming units 3 (Y, M, C, K) supports the photosensitive member 4 serving as a latent image carrier and various devices disposed around the photosensitive member 4 as a unit by a common support. It can be attached to and detached from the copying machine 100 main body. Taking the black image forming unit 3K as an example, this has a developing device 6K for developing the electrostatic latent image formed on the surface of the photosensitive member 4K into a black toner image in addition to the photosensitive member 4K. Further, it also includes a drum cleaning device 9K that cleans transfer residual toner adhering to the surface of the photosensitive member 4K after passing through a primary transfer nip for K described later. In the copying machine 100, a so-called tandem type in which four image forming units 3 (Y, M, C, K) are arranged to face an intermediate transfer belt 25, which will be described later, along the endless movement direction. It is configured.

  FIG. 4 is an enlarged view of one of the four image forming units 3 (Y, M, C, K). The four image forming units 3 (Y, M, C, K) have substantially the same configuration except that the colors of the toners to be used are different from each other. Therefore, in FIG. , C, K are omitted. As shown in FIG. 4, the image forming unit 3 includes a developing device 6, a charging roller 7 of a charging device, a discharging lamp 8 of a discharging device, a drum cleaning device 9, and the like around the photoreceptor 4.

  In the copying machine 100, a drum-shaped member in which a photosensitive layer is formed by coating a photosensitive organic photosensitive material on a base tube made of aluminum or the like is used as the photosensitive member 4. However, an endless belt may be used as the photoreceptor.

The developing device 6 carries a two-component developer containing a magnetic carrier (not shown) and a non-magnetic toner on a developing roller 61 which is a developer carrying member, and a developing region which is a facing portion between the developing roller 61 and the photosensitive member 4. The toner is supplied to the electrostatic latent image on the photosensitive member 4 to visualize the electrostatic latent image. Further, the developing device 6 includes a developer accommodating portion that accommodates the two-component developer supplied to the surface of the developing roller 61, and the developer accommodating portion is provided with a stirring member (not illustrated) that agitates the accommodated two-component developer. It has been.
The developing roller 61 includes a non-magnetic cylindrical developing sleeve that is rotatably arranged, and a magnet roller that is non-rotatably provided inside the developing roller 61. The magnet roller has a plurality of magnetic poles that are sequentially arranged in the rotation direction of the developing sleeve. Each of these magnetic poles applies a magnetic force to the two-component developer on the developing sleeve at a predetermined position in the rotational direction. As a result, the two-component developer in the developer accommodating portion is attracted and carried on the surface of the developing sleeve, and a magnetic brush is formed along the magnetic force lines on the surface of the developing sleeve.
The magnetic brush is transported to the developing region after being regulated to an appropriate layer thickness when passing through a position facing a developer regulating member (not shown) as the developing sleeve rotates. Then, development is performed by transferring toner onto the electrostatic latent image by a potential difference between the developing bias applied to the developing sleeve and the electrostatic latent image on the photoreceptor 4. Further, the two-component developer constituting the magnetic brush that has passed through the developing region and then returned to the developing device 6 again with the rotation of the developing sleeve is developed under the influence of the repulsive magnetic field formed between the magnetic poles of the magnet roller. After detachment from the sleeve surface, it is returned to the developer container. A toner concentration sensor (not shown) is disposed in the developer accommodating portion, and the toner concentration of the two-component developer in the developer accommodating container is within a predetermined range based on the detection result by the toner concentration sensor. As described above, a toner replenishing device (not shown) is controlled so that an appropriate amount of toner is replenished to the two-component developer. The developing device 6 of the present embodiment is a type that performs development using a two-component phenomenon agent, but the developing device 6 is a type that performs development using a one-component developer that does not include a magnetic carrier instead of the two-component developer. Things may be used.

  As shown in FIG. 3, the printer unit 1 includes the image forming process described so far in the photosensitive members 4 (Y, M, C, K) of the four image forming units 3 (Y, M, C, K). As a result, Y, M, C, and K toner images are formed.

  As shown in FIG. 3, a transfer unit 20 is disposed below the four image forming units 3 (Y, M, C, K). The transfer unit 20 includes an intermediate transfer belt 25 as a toner image carrier stretched by a plurality of stretching rollers (22, 23, 21), and the first stretching roller 22 is sandwiched between the intermediate transfer belts 25. A belt cleaning device 24 is disposed at the facing position. The belt cleaning device 24 is arranged to remove toner remaining on the intermediate transfer belt 25 after passing through a secondary transfer nip described later.

In the transfer unit 20, the intermediate transfer belt 25 is driven in the clockwise direction (FIG. 3) by driving the transfer belt driving roller 21 while the intermediate transfer belt 25 is in contact with the photoreceptor 4 (Y, M, C, K). It is moved endlessly (in the direction of arrow A). As a result, primary transfer nips for Y, M, C, and K where the photoreceptors 4 (Y, M, C, and K) and the intermediate transfer belt 25 abut are formed. In the vicinity of the primary transfer nip for Y, M, C, and K, the intermediate transfer belt 25 is moved by the primary transfer roller 26 (Y, M, C, and K) of the primary transfer device disposed inside the loop of the intermediate transfer belt 25. Is pressed toward the photoreceptor 4 (Y, M, C, K). A primary transfer bias is applied to each of the four primary transfer rollers 26 (Y, M, C, K) by a power source (not shown). Thus, in the primary transfer nip for Y, M, C, and K, the primary image that electrostatically moves the toner image on the photoreceptor 4 (Y, M, C, and K) toward the intermediate transfer belt 25 that is a transfer body. A transfer electric field is formed. In the drawing, a toner image is sequentially formed at each primary transfer nip on the front surface of the intermediate transfer belt 25 that sequentially passes through the primary transfer nips for Y, M, C, and K with endless movement in the clockwise direction. Overlaid and primary transferred. By this primary transfer of superposition, a four-color superposed toner image (hereinafter referred to as a four-color toner image) is formed on the front surface of the intermediate transfer belt 25.
The primary transfer device of the present embodiment employs a configuration including the primary transfer roller 26 as a primary transfer member, but a conductive brush, a non-contact corona charger, or the like can also be employed as the primary transfer member.

  Transfer residual toner that has not been primarily transferred to the intermediate transfer belt 25 at the primary transfer nip and has adhered to the surface of the photoreceptor 4 after passing through the primary transfer nip is removed by the drum cleaning device 9 of the image forming unit 3 by the drum cleaning device 9. 4 is removed from the surface.

In this embodiment, the drum cleaning device 9 is a device that scrapes and removes transfer residual toner from the surface of the photoconductor 4 after passing through the primary transfer nip by a polyurethane rubber cleaning blade 91 in contact with the photoconductor 4. It is used. The cleaning blade 91 is bonded (hot melted) to a metal support member fixed to the casing of the image forming unit 3, and comes into contact with the photoconductor 4 in the counter direction. The counter direction is the direction of the blade such that the front end side of the cleaning blade 91 that is cantilevered by the support member is positioned upstream of the rear end side (free end side) in the rotation direction of the photosensitive member 4. .
Here, the toner recovered by the drum cleaning device 9 is recovered by the developing device 6 and reused by a recovery screw and a toner recycling device (not shown).
In this embodiment, a blade is used as the drum cleaning device 9, but a device that removes transfer residual toner by another method may be used.

  The static eliminator included in the image forming unit 3 includes a static eliminator lamp 8 and irradiates light to initialize the surface potential of the photoreceptor 4. The surface of the photoconductor 4 neutralized by the static elimination lamp 8 is uniformly charged by a charging roller 7 that generates a discharge with the photoconductor 4 by applying a charging bias, and then the light by the optical writing device 2 is used. Write processing is performed. The charging device provided in the image forming unit 3 is a contact charging type charging device employing a charging roller 7. In this charging device, the surface of the photosensitive member 4 is uniformly charged by bringing the charging roller 7 into contact with the surface of the photosensitive member 4 and applying a voltage to the charging roller 7. In addition, as a charging device for uniformly charging the photosensitive member 4, a charging device of a non-contact charging type using a scorotron charger or the like can be used instead of the charging roller type.

  As shown in FIG. 3, an endless paper conveyance belt 29, which is a secondary transfer belt, is stretched between a conveyance belt drive roller 29b and a secondary transfer roller 29a below the transfer unit 20 in the drawing. A paper transport unit 28 as a secondary transfer unit for endless movement is provided. In the copying machine 100, the intermediate transfer belt 25 and the paper transport belt 29 are sandwiched between the secondary transfer roller 29 a of the paper transport unit 28 and the transfer backup roller 23 of the transfer unit 20. As a result, a secondary transfer nip is formed in which the front surface of the intermediate transfer belt 25 and the front surface of the paper transport belt 29 abut. A secondary transfer bias is applied to the secondary transfer roller 29a by a power source (not shown). On the other hand, the transfer backup roller 23 of the transfer unit 20 is grounded. Thereby, a secondary transfer electric field is formed in the secondary transfer nip. The member that forms the secondary transfer nip by contacting the intermediate transfer belt 25 is not limited to a belt-like member such as the paper transport belt 29, and a roller-like transfer roller may be used.

  A registration roller pair 15 is disposed on the right side of the secondary transfer nip in the drawing. The registration roller pair 15 feeds the transfer paper P sandwiched between the rollers to the secondary transfer nip at a timing that can be synchronized with the four-color toner image on the intermediate transfer belt 25. In the secondary transfer nip, the four-color toner images on the intermediate transfer belt 25 are collectively transferred to the transfer paper P due to the influence of the secondary transfer electric field and the nip pressure, and combined with the white color of the transfer paper P, a full color image is formed. The transfer paper P, which has passed through the secondary transfer nip and has a toner image transferred to the surface thereof, is separated from the intermediate transfer belt 25 and is held on the front surface of the paper transport belt 29. It is conveyed to the fixing device 30.

  The transfer residual toner that has not been transferred to the transfer paper P at the secondary transfer nip adheres to the surface of the intermediate transfer belt 25 that has passed through the secondary transfer nip. This transfer residual toner is scraped off and removed by a belt cleaning device 24 arranged so that the cleaning member contacts the intermediate transfer belt 25.

  As will be described in detail later, the transfer paper P conveyed to the fixing device 30 is fed out of the fixing device 30 by applying a fixing solution in the fixing device 30 and then sent out from the fixing device 30 to be discharged from the paper discharge tray. 10 is discharged.

  As shown in FIG. 2, in the copying machine 100, a switchback device 36, which is a transfer paper reversing device, is disposed below the paper transport unit 28 and the fixing device 30. When image formation is performed on both sides, the path of the transfer paper P that has undergone image fixing processing on one side is switched to the switchback device 36 side by controlling the switching claw, and the transfer paper P is reversed there, and then again. Transport toward the next transfer transfer nip. Then, the transfer sheet P on which the image is subjected to the secondary transfer process and the fixing process on the other side is discharged onto the discharge tray 10.

  FIG. 5 is an enlarged configuration diagram illustrating the fixing device 30 of the copying machine 100 according to the embodiment. The fixing device 30 is configured to foam the liquid fixing solution 132 into a foam fixing solution F, and to fix the foam fixing solution F generated by the foam fixing solution generation unit 130 to the unfixed state. The image forming apparatus includes a fixing liquid application unit 140 applied to the toner image T. The fixing liquid application unit 140 includes an application roller 141, a pressure roller 143, a film thickness adjustment blade 142, and the like. The application roller 141 is an application member that supports the foam-like fixing liquid F generated by the foam-type fixing liquid generation unit 130 on the surface and applies it to the transfer paper P at the application nip C. The pressure roller 143 is a member that includes an elastic layer, faces the application roller 141, and presses the transfer paper P conveyed between the application roller 141. The film thickness adjusting blade 142 is a member of the application roller 141. This is a member for controlling the film thickness of the foam-like fixing liquid F carried on the surface.

As shown in FIG. 5, the foamy fixing solution F is dropped between the application roller 141 and the film thickness adjusting blade 142. At this time, since the foam-like fixing liquid F has a low bulk density, the film thickness on the application roller 141 can be increased. As a result, the foamy fixing solution F can be sufficiently applied to the unfixed toner image T, and the unfixed toner image T can be fixed to the transfer paper P. Further, since the bulk density is small, the amount of the fixing solution relative to the volume is sufficiently smaller than that of the liquid fixing solution, so that the residual liquid feeling is prevented from being generated on the transfer paper P on which the fixed toner image Tb is formed. it can.
The film thickness of the foam-like fixing liquid F controlled by the film thickness adjusting blade 142 is the thickness of the unfixed toner image T formed on the transfer paper P, the size of the foam of the foam-like fixing liquid F, the viscosity, The pressure is appropriately selected according to the pressure applied to the unfixed toner image T and the ambient temperature. Further, based on image information (for example, a color image or a black solid image) used in the optical writing device 2 when the unfixed toner image T formed on the transfer paper P is formed, the foam-like fixing liquid F You may comprise so that a film thickness may be controlled.

FIG. 6 is an enlarged configuration diagram illustrating the foamy fixing solution generator 130 of the fixing device 30.
The foam-like fixing liquid generation unit 130 includes a fixing liquid container 131, a conveyance pump 133, a liquid conveyance pipe 134, a coarse bubble generation unit 135, a bubble refinement unit 138, and the like. The fixer container 131 stores the liquid fixer 132 before foaming, and the transport pump 133 transports the liquid fixer 132 from the fixer container 131 to the coarse bubble generator 135 through the liquid transport pipe 134. To do. The coarse bubble generating unit 135 generates coarse bubbles having a bubble diameter of 0.5 to 1 [mm] from the liquid fixing liquid 132 conveyed by the conveyance pump 133. The bubble refining unit 138 divides the coarse bubbles into fine bubbles by applying a shearing force to the foam-like fixing solution F including the coarse bubbles having a large bubble diameter generated by the coarse bubble generating unit 135, A foamy fixing solution F having a small diameter is produced.

  The transport pump 133 is not particularly limited, and a gear pump, a bellows pump, a tube pump, or the like can be used. Among these, it is desirable to use a tube pump. If there is a mechanism that is driven in the fixing liquid, such as a gear pump, the liquid bubbles in the pump, the liquid may be compressible, and the conveyance capability may be reduced. Further, there is a possibility that the liquid fixing liquid 132 is contaminated by the material constituting the driving mechanism, or the driving mechanism is deteriorated by the liquid fixing liquid 132. On the other hand, the tube pump is a mechanism that pushes out the liquid in the tube while deforming the tube, and since there is no mechanism for driving in the liquid to be conveyed, the only member that contacts the liquid fixing liquid 132 is the tube. For this reason, by using a tube having liquid resistance to the liquid fixing solution 132, contamination of the liquid fixing solution 132 and deterioration of pump components can be suppressed. Further, since only the tube is deformed, foaming of the liquid fixing liquid 132 can be suppressed, and a decrease in the conveyance capability can be suppressed.

  The coarse bubble generating unit 135 is provided with an air port 136 and a microporous sheet 137 having a hole diameter of 30 to 100 [μm]. In the coarse bubble generating unit 135, the liquid fixing solution 132 conveyed by the conveying pump 133 flows in, so that a negative pressure is generated in the air port 136 and the air introduced from the air port 136 is mixed with the liquid fixing solution 132. . Furthermore, when the liquid fixing solution 132 mixed with air passes through the microporous sheet 137, a foamy fixing solution F composed of coarse bubbles with uniform bubble diameters is generated.

As a configuration of the coarse bubble generation unit 135, a porous member having an open cell structure with a pore diameter of 30 to 100 μm may be used instead of the microporous sheet 137. Such a porous member is not particularly limited, and examples thereof include a sintered ceramic plate, a nonwoven fabric, and a foamed resin sheet. Further, as the configuration of the coarse bubble generating unit 135, instead of providing the air port 136 and the microporous sheet 137, the liquid fixer 132 is agitated using a blade-like stirrer, whereby bubbles are formed in the liquid fixer 132. It is also possible to generate a foam-like fixing solution F made of coarse bubbles while entraining. Further, as the configuration of the coarse bubble generating unit 135, the foamy fixing solution F made of coarse bubbles may be generated by bubbling the liquid fixing solution 132 using an air supply pump or the like.
Regardless of the configuration of the coarse bubble generation unit 135, bubbles having a relatively large bubble diameter of, for example, about 0.5 to 1 [mm] can be generated in a very short time. However, it is desirable to make the foam for fixing as fine as possible. Therefore, in the copying machine 100, the coarse bubbles of the foam-like fixer F obtained by the coarse bubble generation unit 135 are refined by the foam refinement unit 138.

The foam-like fixing solution F containing coarse bubbles generated by the coarse bubble generating unit 135 is supplied to the bubble refining unit 138 through the bubble transport pipe 138c.
The bubble refining part 138 is divided into two or more and refined by applying a shearing force to the coarse bubbles. The bubble refining portion 138 has a double cylindrical structure in which the rotatable inner cylinder 138b is included in the outer cylinder 138a. A foam-like fixer F containing coarse bubbles is supplied to a gap between the outer cylinder 138a and the inner cylinder 138b from a position where the bubble conveyance pipe 138c of the outer cylinder 138a is connected, and the inner cylinder 138b is allowed to pass through the gap. A shearing force is applied to the foamy fixing solution F by rotation. By this shearing force, one coarse bubble is divided into two or more fine bubbles, and a foam-like fixing having a desired fine bubble diameter is supplied from the bubble outlet 138d provided in the outer cylinder 138a to the bubble supply nozzle 139. The liquid F is discharged. In addition, a spiral groove may be provided on the outer periphery of the inner cylinder 138b to improve the transportability of the foam-like fixing liquid F in the outer cylinder 138a.

  In this way, a coarse bubble generating unit 135 that foams the liquid fixing solution 132 into a foamy fixing solution F containing coarse bubbles, and a bubble refining unit 138 that applies shear force to the coarse bubbles to divide them into fine bubbles. In combination, the liquid fixing solution 132 can be changed to a foamy fixing solution F composed of micro bubbles of about 5 to 50 [μm] in a very short time.

The bulk density of the foam-like fixing solution F is preferably in the range of 0.01 to 0.1 [g / cm ³ ], more preferably in the range of 0.01 to 0.05 [g / cm ³ ], and The range of 025-0.05 [g / cm < ³ >] is especially preferable. When the bulk density is less than 0.01 [g / cm ³ ], the provision of reduced H bitterness may be insufficient. When the bulk density exceeds 0.1 [g / cm ³ ], the transfer paper P after fixing is applied. A feeling of residual liquid may occur.
Moreover, it is preferable that the bubble-shaped fixing solution F applied to the transfer paper P has a bubble diameter of 5 to 50 [μm]. As a result, the foam-like fixing liquid F can be applied to the toner image without disturbing the toner image formed of toner particles having a particle diameter of 5 to 10 [μm] formed on the transfer paper P.
Further, the fixing solution only needs to be foamed when applied to a layer of resin-containing fine particles such as toner on the transfer paper P, and does not need to be foamed in the fixing solution container 131. The fixing liquid container 131 is in a liquid state that does not contain bubbles, and is formed into a foam state at the time when the liquid is supplied from the container or on the liquid conveyance path until it is applied to the resin-containing fine particle layer. The transportation volume and the storage volume can be reduced, and the transportation cost and the storage cost can be reduced.

As shown in FIG. 5, the foam-like fixing solution F made of microbubbles obtained in the bubble refining unit 138 is supplied to the surface of the application roller 141 through the nozzle 139. The thickness of the supplied foam-like fixing solution F on the surface of the application roller 141 is adjusted by a film thickness adjusting blade 142 whose tip is opposed to the surface of the application roller 141 with a predetermined gap. The
As shown in FIG. 7 and FIG. 8, the film thickness adjusting blade 142 is cantilevered and rotates about the blade rotation shaft 142a on the fixed end side. For example, the gap with the roller 141 is changed between 10 [μm] and 100 [μm]. A control unit (not shown) adjusts the gap by rotating the blade by driving a motor. When the film thickness of the foam-like fixing liquid F on the surface of the application roller 141 is relatively thin, the gap is made small as shown in FIG. When the thickness is made relatively thick, the gap is adjusted to be large as shown in FIG.

  As a configuration for adjusting the film thickness of the foam-like fixing solution F on the surface of the coating roller 141, the film thickness may be adjusted by a wire bar instead of the film thickness adjusting blade 142. In this case, compared to the film thickness adjusting blade 142, the film thickness in the axial direction on the surface of the coating roller 141 can be made uniform.

  A pressure roller 143 having an elastic layer is in contact with the application roller 141 for applying the foamy fixing solution F to the transfer paper P on which the toner image is formed, thereby forming an application nip C. The transfer paper P transported from the secondary transfer nip toward the fixing device 30 by the paper transport belt 29 described above is sandwiched in the coating nip C with the image surface facing the coating roller 141. In the application nip C, the foamy fixing solution F on the application roller 141 is applied to the image surface.

  The pressure roller 143 is configured using a sponge (elastic porous body) that can be greatly deformed with a weak pressure as an elastic layer. Thereby, the nip time of 50-300 [ms] is securable. At this time, after the foamy fixing solution F penetrates the unfixed toner image T and reaches the transfer paper P, the application roller 141 and the transfer paper P can be separated by heating by a heating device 120 described later in detail. It is necessary to adjust the nip time.

Here, the nip time is a ratio of the nip width to the transfer speed of the transfer paper P, and can be calculated by an equation “(nip width) / (paper transfer speed)”. At this time, the “paper transport speed” can be obtained from design data of the paper transport drive mechanism. Further, the “nip width” is obtained by applying a thin color paint on the entire surface of the application roller 141 and then pressing the transfer paper P between the application roller 141 and the pressure roller 143 to apply the color paint to the transfer paper P. And the length of the colored paint adhering to the transfer paper P in the paper conveyance direction can be determined.
Therefore, in order to obtain a desired nip time, it is necessary to adjust the nip width according to the transfer speed of the transfer paper P. The nip width can be adjusted by changing the distance between the axes of the application roller 141 and the pressure roller 143.

The sponge used for the elastic layer of the pressure roller 143 is preferably made of a material that does not dissolve or swell in the softener, but is a flexible film in which the surface of the elastic layer made of sponge does not dissolve or swell in the softener. It may be a covered configuration. The material for the sponge is not particularly limited, and examples thereof include polyethylene, polypropylene, and polyamide. Further, the flexible film is not particularly limited, and examples thereof include polyethylene terephthalate, polyethylene, polypropylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), and the like.
As the elastic layer of the pressure roller 143, elastic rubber may be used instead of sponge.

  The fixing device 30 includes a leading edge detection sensor 122 that detects the leading edge of the transfer paper P, and the foamy fixing liquid F is applied only on the transfer paper P in accordance with a detection signal of the leading edge detection sensor 122. Then, control is performed so that a thin film of the foam-like fixing liquid F is formed on the application roller 141. As a result, even when the application roller 141 and the pressure roller 143 are always in contact with each other, the foam-like fixing liquid F on the application roller 141 is transferred to the pressure roller 143 during standby when the transfer paper P is not conveyed. It can suppress adhering to.

  Further, the fixing device 30 is provided with a contact / separation mechanism that contacts and separates the application roller 141 and the pressure roller 143 during standby when the transfer paper P is not being transported. The application roller 141 and the pressure roller 143 may be in contact with each other only when the foamy fixing solution F is applied. At this time, it is preferable that the application roller 141 and the pressure roller 143 are brought into contact with each other in accordance with a detection signal of the tip detection sensor 122. Furthermore, it is preferable to provide a trailing edge detection means for detecting the trailing edge of the transfer paper P, and to separate the application roller 141 and the pressure roller 143 in accordance with a detection signal from the trailing edge detection means.

  Further, the fixing device 30 may have a pair of smoothing rollers (hard rollers) that pressurize the transfer paper P on which the fixed toner image Tb is formed. As a result, the surface of the fixed toner image Tb is smoothed, and gloss can be imparted. Furthermore, the fixing property of the fixed toner image Tb to the transfer paper P can be improved.

  The fixing device 30 uses a liquid fixing solution 132 containing a softening agent, a foaming agent, and water that softens fine particles containing the resin by dissolving or swelling at least a part of the resin. Then, it is applied to the resin-containing fine particles on the surface of the recording medium as a foamy fixing solution F. Thus, a fixing method is adopted in which the resin-containing fine particles on the surface of the recording medium are softened and the resin-containing fine particles are fixed on the recording medium. Needless to say, the resin-containing fine particles described here are not particularly limited. Any fine particles containing a resin may be used, and fine resin-containing fine particles containing a conductive member may be used. When applied to an image forming apparatus such as the copying machine 100, the resin-containing fine particles refer to toner.

When the resin-containing fine particles are toner, the toner contains a colorant, a charge control agent, a binder resin, and a release agent, and further contains other components as necessary. Although it does not specifically limit as resin contained in a toner, A polystyrene, a styrene-acryl copolymer, polyester etc. are mentioned, You may use 2 or more types together. Although it does not specifically limit as a mold release agent, Carnauba wax, polyethylene wax, etc. are mentioned, You may use 2 or more types together.
The toner is preferably subjected to a water-repellent treatment by fixing hydrophobic particles such as hydrophobic silica having a methyl group and hydrophobic titanium oxide to the surface of the toner.

  The recording medium is not particularly limited, and examples thereof include paper (standard plain paper, continuous paper, letter paper, postcard, cardboard, etc.), cloth, plastic films such as OHP sheets, metals, resins, ceramics, and the like. . At this time, the recording medium preferably has permeability to the fixing solution. Examples of such a recording medium include a substrate that is permeable to a fixing solution and a layer on which a layer that is permeable to a fixing solution is formed. Further, the form of the recording medium is not particularly limited, and examples thereof include a three-dimensional object having a flat surface and a curved surface in addition to a sheet-like material.

When the foam fixing solution is applied to the recording medium using an application member such as the application roller 141 of the fixing device 30, the foam fixing solution is attached to both surfaces of the recording medium and the application member due to the adhesive force of the bubbles. As a result, the recording medium may stick to the application member via the foamy fixing solution, and jamming may occur.
The occurrence of a jam in the fixing device may also occur in the dry fixing method when the recording medium sticks to a fixing member that contacts a toner image on the recording medium such as a fixing roller or a fixing belt. In order to prevent the occurrence of such a jam, a separation mechanism such as a separation claw is provided in the vicinity of the surface of a fixing member such as a fixing roller that has passed through a fixing nip for separation of a recording medium in a fixing device for dry fixing. It is often done. However, when the separation claw is in direct contact with the fixing member, although the separation performance of the recording medium is high, there is a problem that the surface of the fixing member is damaged by the separation claw.

As a fixing device for preventing such a problem, for example, a fixing device described in Patent Document 2 has a configuration in which a separation claw is disposed at a position separated by a minute distance from a fixing member. Accordingly, the recording paper can be separated without the separation claw damaging the fixing member.
However, a configuration in which the separation claw is separated from the fixing member by a minute distance as in the fixing device described in Patent Document 2 is in contact with the separation claw with the tip of the recording medium floating from the surface of the fixing member. Separation function works. For this reason, in the configuration in which the foam-like fixing solution is applied as in the fixing device 30 of the present embodiment, when the foam-like fixing solution is applied to the entire surface of the recording medium, the recording medium is stretched from the tip to the surface of the coating member. attached. For this reason, even if the separation claw is provided at a position separated from the application member by a minute distance in the configuration in which the foam-like fixing solution is applied, the separation claw is difficult to catch the front end of the recording medium, and the separation function does not easily work. If the recording medium is permeable to a fixing solution such as paper, the fixing solution penetrates into the recording medium by applying a foamy fixing solution, and the recording medium containing the liquid component is stiff. become weak. For this reason, if the recording medium is separated from the application member only by the separation claw, there is a possibility that the recording medium that has become weak may be wrinkled or broken.

In the fixing device 30 of the present embodiment, a paper using a heating device 120 is used in order to improve the separation of the recording medium from the coating member by applying a foamy fixing solution to the recording medium with the coating member. A separation mechanism is provided.
FIG. 1 is an enlarged explanatory view of a paper separating mechanism of the fixing device 30.
As shown in FIG. 1, the fixing liquid application unit 140 of the fixing device 30 includes a heating device 120 that heats the application roller 141 and a leading edge detection sensor 122 that detects the leading edge of the transfer paper P being conveyed. Furthermore, it has the heating control apparatus 123 which controls operation | movement of the heating apparatus 120 according to the detection signal sent from the front-end | tip detection sensor 122, and the cooling device 121 which cools the coating roller 141 after a heating.

The foamy fixing solution F carried on the application roller 141 is applied to the transfer paper P and the unfixed toner image T which are conveyed at the application nip C. At this time, a signal is transmitted from the heating control device 123 to the heating device 120 so that heating is started at the timing when the leading edge of the transfer paper P detected by the leading edge detection sensor 122 passes through the center of the coating nip C. By performing heating by the heating device 120, the foam-like fixing liquid F on the surface of the application roller 141 is heated through the application roller 141, and bubbles are broken. Thereby, bubbles existing between the transfer paper P and the fixed toner image Tb and the application roller 141 are broken, and the leading edge of the transfer paper P is separated from the application roller 141. If the leading edge of the transfer paper P is sufficiently separated, the leading edge of the transfer paper P can be easily separated from the leading edge. With such a configuration, the transfer paper P can be stably separated from the application roller 141.
The surface of the application roller 141 that has passed through the region heated by the heating device 120 is cooled by the cooling device 121. Thereby, it is possible to prevent the foamy fixing solution F just supplied from the foamy fixing solution generator 130 to the application roller 141 from being broken by the heat of the application roller 141 heated to a high temperature.

  As the heating device 120, heating means such as blowing hot air, radiant heat, resistance heating, induction heating, or the like can be applied as a configuration for heating the application roller 141. However, when using hot air blowing or radiant heat as the heating means, it is desirable to heat from the inside of the application roller 141. When heated from the outside of the application roller 141, the transfer paper P, the fixed toner image Tb, etc. are deprived of heat, and heat is not easily transferred to the bubbles on the application roller 141. May not be separated.

  The leading edge detection sensor 122 is a reflective sensor that can determine the hue, and can detect a change in hue when the leading edge of the transfer paper P passes. The heating control device 123 determines the passage of the leading edge of the transfer paper P from the change in hue detected by the leading edge detection sensor 122. Then, the heating control device 123 determines the leading edge of the transfer paper P from the center of the coating nip C based on the conveyance speed set in advance in the fixing device 30 and the distance from the position detected by the leading edge detection sensor 122 to the center of the coating nip C. The timing of passing is calculated, and control is performed to operate the heating device 120 at that moment.

Although it does not specifically limit as the cooling device 121, It is preferable to cool by ventilation from the simplicity of an apparatus.
Further, a separation claw (not shown) that assists in separation of the transfer paper P may be disposed on the downstream side of the region to be heated of the application roller 141. Since the leading edge of the transfer paper P is separated, the entire transfer paper P can be more reliably separated from the application roller 141 by the separation claw.

[Experiment]
An experiment for evaluating the separation property of the transfer paper P and the fixed image by using the fixing solution obtained in “Example of Fixing Solution” to be described later and changing the fixing conditions in “Example of Image Forming Method” to be described later. Went.
(Preparation example of fixing solution)
Fatty acid in which the mass ratio of myristic acid (manufactured by Kanto Chemical Co., Inc.), palmitic acid (manufactured by Kanto Chemical Co., Ltd.), stearic acid (manufactured by Kanto Chemical Co., Ltd.) was 4: 3: 1, and diethanolamine (a neutralizing agent) (Made by Kanto Chemical Co., Inc.) was measured so that the molar ratio was 1: 0.7, stirred in ion exchange water at a liquid temperature of 80 [° C.] for 30 minutes, and allowed to cool to room temperature. Fatty acid diethanolamine salt was prepared.
30 [wt%] dicarbitol succinate (manufactured by Higher Alcohol Industry Co., Ltd.) as a softening agent, 4 [wt%] the fatty acid diethanolamine salt as a foaming agent, and palm oil fatty acid diethanolamide (1: 1) as a foaming agent The mold (Matsumoto Yushi Seiyaku Co., Ltd., Marpon MM) 0.5 [wt%], ion-exchanged water 65.5 [wt%] as a diluent was stirred for 10 minutes with an ultrasonic homogenizer, and the fixing solution was Prepared.

(Example of image forming method)
An unfixed toner image (color image) was formed on PPC paper swing mat 45k paper (manufactured by Mitsubishi Paper Industries) using an electrophotographic printer IpsioColor CX8800 (manufactured by Ricoh Company). Next, an unfixed toner image was fixed using the fixing device 30 having the configuration shown in FIG.
In the fixing device 30, the liquid fixing solution is foamed using the foamy fixing solution generator 130 having the configuration shown in FIG. 6. The fixer container 131 is a bottle made of PET resin, and the transport pump 133 is a tube pump having a tube made of silicone rubber and an inner diameter of 2 [mm], and has a flow path for transporting the liquid fixer 132. The liquid conveyance pipe 134 to be formed is a silicone rubber tube having an inner diameter of 2 [mm].

The microporous sheet 137 of the coarse bubble generating unit 135 is a 400 mesh sheet made of stainless steel having an opening of about 40 [μm]. Further, the outer cylinder 138a and the inner cylinder 138b are made of PET, the inner cylinder 138b has an outer diameter of 8 [mm] and a length of 100 [mm], and the outer cylinder 138a has an inner diameter of 10 [mm]. The length is 120 [mm]. The inner cylinder 138b of the bubble refining unit 138 is fixed to a rotation shaft and is rotated by a rotation drive motor (not shown).
With such a configuration, a foam-like fixing solution F is prepared from the liquid fixing solution 132 and the obtained foam-like fixing solution F is supplied to the application roller 141.

As the application roller 141, a SUS roller having a diameter of 30 [mm] baked and coated with PFA resin is used, and as the pressure roller 143, an aluminum alloy roller (core metal) having a diameter of 10 [mm] has an outer diameter. The polyurethane foam material color foam EMO (manufactured by Inoac Co., Ltd.) was used so as to be 50 [mm]. At this time, the nip pressure was adjusted so that the nip width between the application roller 141 and the pressure roller 143 was 15 [mm]. The heating device 120 uses an induction heating system and is configured to heat from the center of the coating nip C on the surface of the coating roller 141 to the downstream 15 [mm] in the transport direction. Heating by the heating device 120 was performed only while the leading edge of the transfer paper P passed from the center of the coating nip C to 15 [mm] downstream in the transport direction. As the cooling device 121, a cross flow fan was used, and the application roller 141 was cooled by blowing air at an air volume of 360 [m ³ / h]. Further, as the film thickness adjusting blade 142, a parallel plate glass having a thickness of 1 [mm] is bonded to a support plate made of an aluminum alloy, the glass surface is directed to the coating roller 141 side, and the gap with the coating roller 141 is set to 100. The thickness of the foamy fixing solution F on the application roller 141 was adjusted to about 130 [μm] as [μm]. The transfer speed of the transfer paper P was set to 300 [mm / sec]. At this time, the thickness of the unfixed toner image T was set to 30 to 40 [μm].

The following are differences between the fixing solution preparation examples and the image forming method examples that are different from the other examples of the common examples and the comparative examples.
In Example 1, fixing was performed by using a foamy fixing solution F having a bulk density of 0.03 [g / cm ³ ] and setting the surface temperature of the heated portion of the coating roller 141 to 50 [° C.].
In Example 2, a foamy fixing solution F having a bulk density of 0.03 [g / cm ³ ] was used, and the surface temperature of the heated portion of the application roller 141 was set to 70 [° C.] for fixing.
In Example 3, the foamed fixing solution F having a bulk density of 0.05 [g / cm ³ ] was used, and the surface temperature of the heating portion of the coating roller 141 was set to 50 [° C.] for fixing.
In Example 4, a foamy fixing solution F having a bulk density of 0.05 [g / cm ³ ] was used, and the surface temperature of the heated portion of the application roller 141 was set to 70 [° C.] for fixing.
In Comparative Example 1, a foamy fixing solution F having a bulk density of 0.03 [g / cm ³ ] was used, and fixing was performed without heating by the heating device 120 and cooling by the cooling device 121.
In Comparative Example 2, a foamy fixing solution F having a bulk density of 0.05 [g / cm ³ ] was used, and fixing was performed without heating by the heating device 120 and cooling by the cooling device 121.
In Comparative Example 3, a foamy fixing solution F having a bulk density of 0.05 [g / cm ³ ] is used, the surface temperature of the heating part of the application roller 141 is set to 70 [° C.], and the heating region is set to the application roller 141. The distance between the center of the coating nip C and the upstream 15 [mm] in the conveying direction was fixed.
Comparative Example 4 uses a foam-like fixer F having a bulk density of 0.05 [g / cm ³ ], sets the surface temperature of the heating portion of the application roller 141 to 70 [° C.], and cools by the cooling device 121. Established without doing.

As an evaluation of the separation property of the transfer paper P, 20 images were continuously fixed using the fixing device 30, and the separation performance was evaluated from the number of sheets on which the transfer paper P stuck to the surface of the coating roller 141 and was not separated.
As the evaluation of the fixed image, simultaneously with the evaluation of the separation property of the transfer paper P, the degree of toner offset was evaluated according to the following criteria for the fixed images of the first sheet and the 20th sheet.
“◯”: No toner offset has occurred “×”: Toner offset has occurred and the image is greatly disturbed “-”: Not evaluated Table 1 shows the evaluation results.

  From the results of Examples 1 to 4 in Table 1, it was suggested that the separation property of the transfer paper P can be improved without disturbing the image by heating the downstream side in the conveyance direction when viewed from the center of the coating nip C. Without heating, poor separation occurred (Comparative Example 1 and Comparative Example 2). Further, when the upstream in the conveying direction as viewed from the center of the coating nip C was heated, no fixing failure occurred, but fixing failure due to toner offset occurred (Comparative Example 3). Further, when cooling is not performed, toner offset gradually occurs during continuous paper feeding. In Comparative Example 1 and Comparative Example 2, paper jam frequently occurred and toner offset evaluation could not be performed. From this experiment, it is suggested that the fixing device having the characteristic portion of the present invention can prevent the occurrence of paper jam due to the sticking of the transfer paper P without disturbing the image.

[Modification]
FIG. 9 is an enlarged configuration diagram showing a fixing device 30 according to a modified example to which the present invention can be applied.
FIG. 5 shows the fixing device 30 except that the pressure belt 75 is used instead of the pressure roller 143 of the fixing device 30 shown in FIG. 5 as a member that contacts the application member at the application nip C. The configuration is the same as that of the fixing device 30.
. The endless pressure belt 75 is endlessly moved in the counterclockwise direction in the drawing by the rotational drive of any one pressure tension roller 76 while being stretched by a plurality of pressure tension rollers 76. And the application | coating nip C is formed by making the expansion | deployment location between rollers contact | abut to the application roller 141. FIG. By bending the pressure belt 75 flexibly along the surface of the application roller 141, the application nip C having a longer nip width than that when the pressure roller 143 is used can be formed. The pressure belt 75 is not particularly limited. For example, a member obtained by coating a base such as a seamless nickel belt or a seamless PET film with a releasable fluororesin such as PFA is used.
In addition, as a fixing device to which the present invention can be applied, an application belt having an endless belt shape is used instead of the application roller 141 of the fixing device 30 shown in FIG. The structure which forms C may be sufficient.

FIG. 10 is an explanatory diagram of the printer unit 1 of another example of the image forming apparatus in which the fixing device 30 to which the present invention is applied can be arranged.
In the printer unit 1 of FIG. 10, the same components as those of the printer unit 1 described with reference to FIGS. 3 and 4 are denoted by the same reference numerals and description thereof is omitted. The printer unit 1 shown in FIG. 10 includes a transfer conveyance belt 250 that is stretched by a first support roller 251 and a second support roller 252 and moves on the surface in the direction of arrow B in FIG. The printer unit 1 shown in FIG. 10 transfers the toner images of the respective colors formed on the four drum-shaped photoconductors 4 (Y, M, C, K) onto the transfer paper P carried on the transfer conveyance belt 250. It is the structure which directly transfers to. Specifically, after the transfer paper P is fed using the registration roller pair 15, the transfer conveyance belt 250 is moved to the photosensitive member 4 using the respective transfer rollers 260 (Y, M, C, K). By pressing, the toner images of the respective colors are sequentially transferred onto the transfer paper P. As a result, the four color toner images are superimposed on the transfer paper P, and combined with the white color of the transfer paper P, the full-color image becomes an unfixed toner image T. The transfer paper P on which the unfixed toner image T is formed is transported to the fixing device 30 by the surface movement of the transfer transport belt 250, and the unfixed toner image T is fixed by the fixing device 30.

  As described above, the fixing device 30 according to the present embodiment is a foam in which bubbles are dispersed in the liquid fixing liquid 132 containing the softening agent that softens the toner that is the resin-containing fine particles by dissolving or swelling at least part of the resin. A recording liquid carrying an unfixed toner image T made of toner with a foam-like fixing liquid generating unit 130 which is a fixing-liquid foaming means for forming a liquid-like fixing liquid F, and the foam-like fixing liquid F supplied to the surface moving surface. A toner layer softened by applying a foam-like fixer F to the transfer paper P at the application nip C, which is an application position, and an application roller 141 that is an application member applied to the surface of the transfer paper P as a medium. Is a fixing device for fixing the toner image onto the transfer paper P. Then, the foamy fixing solution F on the surface of the coating roller 141 on the downstream side in the surface movement direction is heated with respect to the upstream end of the coating nip C where the foamy fixing solution F starts to contact the transfer paper P. The heating device 120 is a heating unit that heats the foamed fixing solution F on the surface of the coating roller 141 after entering the coating nip C by heating with the heating device 120. As a result, the coating roller 141 and the transfer paper P attached via the foamy fixing solution F can be separated, and jamming can be prevented.

  In addition, the fixing device 30 includes a pressure roller 143 that is a facing member that forms the application nip C by contacting the application roller 141 with the transfer paper P sandwiched by the application nip C, and the heating device 120 includes the application nip C. The coating roller 141 on the downstream side in the surface movement direction of the coating roller 141 is heated with respect to the center of the coating roller 141. Thereby, the foamy fixing solution F on the surface of the application roller 141 on the downstream side in the surface movement direction with respect to the center of the application nip C can be heated. Here, the region expressed as “the downstream side in the surface movement direction of the coating roller 141 with respect to the center of the coating nip C” refers to the center of the coating nip C as the upstream end and the downstream end as the coating nip C. Is defined as an area located at an arbitrary position downstream of the application roller 141 in the direction of surface movement, and is not limited to the application nip C. However, when the application member is a roller or an endless belt, the upstream and downstream boundary is a position where the foamy fixing solution F before contacting the toner is supplied to the surface of the application member.

  When heating from the upstream side of the surface moving direction with respect to the center of the coating nip C, bubbles may break before contributing to fixing, and offset and image disturbance may occur. On the other hand, if the heating position is too far downstream of the coating nip C in the surface movement direction, the transfer paper P completely passes through the coating nip C before being separated from the coating roller 141 and causes paper jam without being conveyed. Sometimes. Further, the width of the heating region (the length on the surface of the coating roller 141 from the center of the coating nip C to the downstream end of the heating region) is the bulk density of the foamy fixing liquid F, the type of the recording medium, the nip width, It is necessary to set appropriately according to the conveyance speed of the recording medium. If the width of the heating area is short, the recording medium may not be separated. If the width of the heating area is long, heating may be performed even after the recording medium is separated, and extra energy is consumed. When the bulk density of the foam-like fixing liquid F is high, when a recording medium with low water absorption is used, when the nip width is narrow, when the conveyance speed is high, it is necessary to increase the width of the heating region.

  Further, the heating device 120 of the fixing device 30 heats the foamed fixing liquid F on the surface of the coating roller 141 by heating from the inside of the coating roller 141 and heating the surface of the coating roller 141. As a result, heat deprived by the toner, the transfer paper P, etc. can be reduced, and bubbles remaining between the transfer paper P and the application roller 141 can be broken more efficiently. The transfer paper P and the application roller 141 can be separated.

  Further, the fixing device 30 is positioned on the transfer path of the transfer sheet P upstream of the transfer nip C in the transfer direction of the transfer sheet P, and a leading end detection sensor 122 that is a detection unit that detects the leading end of the transfer sheet P; When the leading edge of the transfer paper P is detected by the leading edge detection sensor 122, control means for controlling the heating device 120 to heat only when the vicinity of the leading edge of the transfer paper P passes through the region heated by the heating device 120. And a heating control device 123. As a result, the leading edge of the transfer paper P and the application roller 141 can be separated, and the transfer paper P from which the leading edge is separated is naturally separated as the transfer paper P is conveyed, so that the transfer paper can be consumed with less energy consumption. P and the application roller 141 can be separated.

  Further, the fixing device 30 passes the surface of the foam fixing solution F on the surface heated by the heating device 120 and then the surface of the coating roller 141 before reaching the position where the foam fixing solution F is supplied. It has a cooling device 121 which is a cooling means for cooling. As a result, when fixing is performed continuously, the foamy fixing solution F before contributing to fixing is carried on the surface of the application roller 141 at a high temperature, and the foamed state before contacting the toner is generated. It is possible to prevent the fixing liquid F from being broken and to perform fixing with higher fixing reliability.

The copying machine 100 as an image forming apparatus of the present embodiment forms a toner image T that forms an unfixed toner image T on a transfer paper P that is a recording medium, using toner containing resin fine particles containing a resin and a colorant. The image forming unit 3 and the like, which are means, and fixing means for fixing the toner image on the transfer paper P are provided, and the fixing device 30 of the present embodiment is used as the fixing means. As a result, paper jam that occurs when the transfer paper P sticks to the application roller 141 can be prevented, and image formation with higher fixing reliability can be performed.
As a configuration for transferring the toner image formed by the image forming unit 3 or the like onto the transfer paper P, the toner image formed on the photosensitive member 4 on the latent image carrier is transferred as in the printer unit 1 shown in FIG. The toner image formed on the photoconductor 4 on the latent image carrier may be opposed to the photoconductor 4 as in the printer unit 1 shown in FIG. A configuration may be employed in which the toner image formed on the intermediate transfer belt 25 is transferred onto the transfer paper P after being transferred to the intermediate transfer belt 25 which is a moving transfer member.

DESCRIPTION OF SYMBOLS 1 Printer part 2 Optical writing device 3 Image forming unit 4 Photoconductor 6 Developing device 7 Charging roller 8 Static elimination lamp 9 Drum cleaning device 15 Registration roller pair 20 Transfer unit 21 Transfer belt drive roller 22 First stretch roller 23 Transfer backup roller 24 belt cleaning device 25 intermediate transfer belt 26 primary transfer roller 28 paper transport unit 29 paper transport belt 29a secondary transfer roller 29b transport belt drive roller 30 fixing device 36 switchback device 37 paper transport path 40 paper feed device 41 paper bank 42 Paper cassette 43 Delivery roller 44 Paper feed path 45 Separation roller 46 Conveyance roller 50 Document conveyance reading unit 51 ADF
61 Developing Roller 91 Cleaning Blade 100 Copying Machine 120 Heating Device 121 Cooling Device 122 Leading Edge Detection Sensor 123 Heating Control Device 130 Foam Fixing Liquid Generating Unit 131 Fixing Solution Container 132 Liquid Fixing Solution 133 Conveying Pump 134 Liquid Conveying Pipe 135 Generating Large Bubbles Part 136 Air port 137 Micropore sheet 138 Foam refinement part 138a Outer cylinder 138b Inner cylinder 138c Foam transport pipe 138d Foam outlet 139 Nozzle 140 Fixing liquid application part 141 Application roller 142 Film thickness adjustment blade 142a Blade rotation shaft 143 Pressurization Roller 150 scanner 151 fixed reading unit 152 moving reading unit 250 transfer conveying belt 251 first support roller 252 second support roller 260 transfer roller C coating nip F foamy fixing liquid P transfer paper T unfixed toner image Tb fixed Toner image

JP 2007-219105 A JP-A-6-156845

Claims (6)

A fixing liquid foaming means for forming a fixing liquid containing a softening agent that softens resin-containing fine particles by dissolving or swelling at least a part of the resin into a foamy fixing liquid in which bubbles are dispersed in the liquid;
An application member that applies the foamy fixing solution supplied to the surface moving surface to a surface of a recording medium carrying a resin-containing fine particle layer composed of the resin-containing fine particles;
In a fixing device for fixing the resin-containing fine particle layer softened by applying the foamy fixing solution on the surface of the coating member to the recording medium at a coating position,
A fixing device comprising heating means for heating the foamy fixing solution on the surface of the coating member on the downstream side in the surface moving direction with respect to a position where the foamy fixing solution starts to contact the recording medium. . The fixing device according to claim 1.
An opposing member that forms an application nip by contacting the application member across the recording medium at the application position;
The fixing device is characterized in that the heating means heats the foamy fixing solution on the surface of the coating member on the downstream side in the surface movement direction of the coating member with respect to the center of the coating nip. The fixing device according to claim 1 or 2,
The fixing device is characterized in that the heating means heats the surface of the coating member to heat the foamy fixing solution on the surface. The fixing device according to any one of claims 1 to 3,
A detection means for detecting the leading edge of the recording medium, which is located in the conveyance path of the recording medium upstream of the coating position in the conveyance direction of the recording medium;
Control means for controlling the heating means to perform heating only at the timing when the vicinity of the tip of the recording medium passes through the region heated by the heating means when the leading edge of the recording medium is detected by the detecting means; A fixing device. The fixing device according to any one of claims 1 to 4,
A cooling means for cooling the surface of the coating member after reaching the position where the foamy fixer is supplied after passing through the region where the foamy fixer on the surface is heated by the heating means; A fixing device characterized. A toner image forming means for forming a toner image on a recording medium using a toner containing resin-containing fine particles containing a resin and a colorant;
Applying a foamy fixer to the surface of the recording medium carrying the toner image to be transferred to the recording medium,
An image forming apparatus comprising fixing means for fixing the toner image on the recording medium,
An image forming apparatus using the fixing device according to claim 1 as the fixing unit.

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