JP2013101298A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device configured so as to efficiently remove a carrier liquid existing in a paper sheet P.SOLUTION: The fixing device includes a heating roll 36 coming into contact with a paper sheet P on which a toner image obtained by development with a developer containing a toner and a carrier liquid is transferred and heating the paper sheet P so as to move the carrier liquid existing in the paper sheet P to the surface of the paper sheet P from the inside of the paper sheet P, a removal blade 38 for removing the carrier liquid adhering to the heating roll 36 from the heating roll 36, and a fixing part 34 arranged on the downstream side of the heating roll 36 in the conveyance direction of the paper sheet P and fixing the toner existing on the paper sheet P to the paper sheet P.

Description

  The present invention relates to a fixing device and an image forming apparatus.

  In Patent Document 1, as shown in FIG. 6 and the like, in a fixing device for heating and fixing an unfixed image on a recording medium formed using a liquid developer in which toner is dispersed in a carrier liquid, the recording medium A preheating section (310) for moving the carrier liquid present in the recording medium to the surface of the recording medium by heating, and the carrier liquid moved from the inside of the recording medium to the surface by the preheating section (310). It is disclosed to provide a carrier removal part (330) for removal from the surface.

JP 2003-167456 A

  An object of the present invention is to provide a fixing device that efficiently removes a carrier liquid present on a recording medium.

  The fixing device according to claim 1 of the present invention is in contact with a recording medium to which a toner image obtained by developing with a developer containing toner and carrier liquid is transferred, and the carrier liquid present in the recording medium is the recording medium. A heating means for heating the recording medium so as to move from the inside to the surface, a removing means for removing the carrier liquid adhering to the heating means from the heating means, and a downstream of the heating means in the transport direction of the recording medium. And fixing means for fixing the toner present on the recording medium to the recording medium.

  A fixing device according to a second aspect of the present invention is the fixing device according to the first aspect, wherein the removing unit is disposed on a side where the heating unit is provided with respect to a conveyance surface of the recording medium, Contact removing means for removing the carrier liquid that has contacted the surface of the recording medium that contacts the heating means and moved to the surface of the recording medium from the recording medium.

  A fixing device according to a third aspect of the present invention is the fixing device according to the second aspect, wherein the contact removing means is a surface side of the recording medium that is in contact with the heating means and on which the toner image is not formed. It is characterized by being in contact with the side.

  A fixing device according to a fourth aspect of the present invention is the fixing device according to the second or third aspect, further comprising a transfer means for transferring the carrier liquid removed by the contact removing means to the heating means, The removing means removes the carrier liquid transferred by the transferring means.

  The fixing device according to a fifth aspect of the present invention is the fixing device according to the third aspect, wherein the heating unit contacts a surface of the recording medium on which the toner image is not formed, and transports the recording medium. The removal means is provided so as to contact the surface of the recording medium that contacts the heating plate, and serves as the contact removal means. The carrier liquid adhering to the downstream edge in the medium conveyance direction is removed from the heating plate, and the carrier liquid that has moved to the surface of the recording medium is removed from the recording medium.

  An image forming apparatus according to a sixth aspect of the present invention develops an image holding body on which an electrostatic latent image is formed, and the electrostatic latent image formed on the image holding body with a developer having toner and carrier liquid. 6. The developing device, a transfer device that transfers a toner image developed by the developing device to a recording medium, and a toner image transferred to the recording medium by the transfer device is fixed to the recording medium. The fixing device according to claim 1 is provided.

  According to the fixing device of the first aspect of the present invention, the carrier liquid present on the recording medium is efficiently removed as compared with the case where the removing means for removing the carrier liquid adhering to the heating means from the heating means is not provided. be able to.

  According to the fixing device of the second aspect of the present invention, the removing unit having the common function of removing the carrier liquid and the contact removing unit are collectively arranged on the same side with respect to the conveyance surface of the recording medium. Can do.

  According to the fixing device of the third aspect of the present invention, the carrier liquid present in the recording medium is more removed than when the contact removing means is in contact with the surface of the recording medium on which the toner image is formed. It can be removed more efficiently.

  According to the fixing device of the fourth aspect of the present invention, the carrier liquid removed by the contact removing means can be removed together with the carrier liquid adhering to the heating means by the removing means.

  According to the fixing device of the fifth aspect of the present invention, the carrier liquid can be directly removed from the recording medium by the removing means while removing the carrier liquid at the downstream edge of the heating plate.

  According to the image forming apparatus described in claim 6 of the present invention, an image having excellent fixability is formed on the recording medium as compared with the case where the fixing apparatus described in any one of claims 1 to 5 is not provided. can do.

1 is a diagram illustrating a configuration of an image forming apparatus including a fixing device according to a first embodiment. It is a figure explaining the behavior of the carrier liquid which exists in the paper at the time of heating a paper with the heating roll of the carrier liquid reduction part of FIG. It is a figure which shows the relationship between the ratio of the carrier liquid which floats on the front surface and back surface of a paper, and the setting temperature of a heating roll. It is a figure which shows the transfer aspect of the carrier liquid in the carrier liquid reduction part of FIG. 2 is a graph showing a relationship between a fixing strength grade of toner fixed by the fixing device of FIG. 1 and a fixing portion set temperature. 2 is a graph showing a relationship between a tape peeling level of toner fixed by the fixing device of FIG. 1 and a fixing unit set temperature. It is a figure which shows the structure of an image forming apparatus provided with the fixing device of 2nd Embodiment. It is a figure which shows the transfer aspect of the carrier liquid in the carrier liquid reduction part of FIG. It is a figure which shows the transfer aspect of the carrier liquid in the carrier liquid reduction part of another aspect of the carrier liquid reduction part of FIG.

  Embodiments of a fixing device and an image forming apparatus according to the present invention will be described below with reference to the accompanying drawings.

(Image forming device)
FIG. 1 shows an image forming apparatus 1 as an example of an image forming apparatus including a fixing device according to the present invention. The image forming apparatus 1 includes four image forming units 10Y, 10M, 10C, and 10K (hereinafter referred to as a subscript “Y”) that are responsible for forming images of different colors among four colors (yellow, magenta, cyan, and black). Is for yellow, “M” is for magenta, “C” is for cyan, and “K” is for black), and 4 are arranged corresponding to the image forming units 10Y, 10M, 10C, and 10K. The image forming units 10Y, 10Y, 20M, 20C, and 20K and the conveying direction (direction indicated by arrow A in the drawing) of continuous paper (hereinafter simply referred to as “paper P”) as an example of a recording medium. 10M, 10C, 10K and a fixing device 30 provided on the downstream side of the transfer devices 20Y, 20M, 20C, 20K. The paper P is transported at a predetermined transport speed by a transport device (not shown) disposed on the downstream side of the fixing device 30 in the transport direction.

  The image forming units 10Y, 10M, 10C, and 10K respectively include photosensitive drums 12Y, 12M, 12C, and 12K as examples of image carriers, charging devices 14Y, 14M, 14C, and 14K, and exposure devices 16Y, 16M, and 16K. 16C, 16K and developing devices 18Y, 18M, 18C, 18K. The photosensitive drums 12Y, 12M, 12C, and 12K are each driven to rotate in a direction (clockwise direction) indicated by an arrow + R in the drawing. The charging devices 14Y, 14M, 14C, and 14K, the exposure devices 16Y, 16M, 16C, and 16K and the developing devices 18Y, 18M, 18C, and 18K are photosensitive in this order in the rotation direction of the photosensitive drums 12Y, 12M, 12C, and 12K. It is arranged around the body drums 12Y, 12M, 12C, 12K.

  The charging devices 14Y, 14M, 14C, and 14K are for charging the surfaces (peripheral surfaces) of the photosensitive drums 12Y, 12M, 12C, and 12K. The exposure devices 16Y, 16M, 16C, and 16K expose the surfaces of the photosensitive drums 12Y, 12M, 12C, and 12K charged by the charging devices 14Y, 14M, 14C, and 14K based on the image data, so that the photosensitive drums are exposed. This is for forming electrostatic latent images on the surfaces of 12Y, 12M, 12C, and 12K. The developing devices 18Y, 18M, 18C, and 18K are visible by developing the electrostatic latent images formed on the surfaces of the photosensitive drums 12Y, 12M, 12C, and 12K by the exposure devices 16Y, 16M, 16C, and 16K with a developer. The toner image is obtained.

  The developer used in the developing devices 18Y, 18M, 18C, and 18K is a liquid type developer (developer including toner and carrier liquid) obtained by dispersing powdered toner in a carrier liquid. The carrier liquid is, for example, paraffin oil, ether oil, silicone oil, vegetable oil, etc., and has a boiling point in the range of 170 ° C. to 300 ° C. (those higher than the boiling point of water (100 ° C.)). To be elected.

  The transfer devices 20Y, 20M, 20C, and 20K include intermediate transfer rolls 22Y, 22M, 22C, and 22K, and backup rolls 24Y, 24M, 24C, and 24K. The intermediate transfer rolls 22Y, 22M, 22C, and 22K are upstream of the charging devices 14Y, 14M, 14C, and 14K in the rotation direction of the photosensitive drums 12Y, 12M, 12C, and 12K, and the developing devices 18Y, 18M, 18C, and 18K. At the primary transfer position X1 on the downstream side thereof, the photosensitive drums 12Y, 12M, 12C, and 12K are contacted and rotated in the direction indicated by the arrow -R (counterclockwise direction). The toner images formed on the surfaces of the photosensitive drums 12Y, 12M, 12C, and 12K are primarily transferred to the intermediate transfer rolls 22Y, 22M, 22C, and 22K at the primary transfer position X1. When the toner image is primarily transferred, the carrier liquid also moves to the intermediate transfer rolls 22Y, 22M, 22C, and 22K. A primary transfer voltage (bias voltage) is applied between the photosensitive drums 12Y, 12M, 12C, and 12K and the intermediate transfer rolls 22Y, 22M, 22C, and 22K.

  The backup rolls 24Y, 24M, 24C, and 24K are arranged to face the intermediate transfer rolls 22Y, 22M, 22C, and 22K on the side opposite to the photosensitive drums 12Y, 12M, 12C, and 12K, and the intermediate transfer rolls 22Y, 22M, and 22K are arranged. The sheet P is rotated in the direction indicated by the arrow + R while being in contact with the sheet P conveyed between 22C and 22K and the backup rolls 24Y, 24M, 24C and 24K. The position at which the intermediate transfer rolls 22Y, 22M, 22C, and 22K contact the paper P is the secondary transfer position X2, and the primary transfer is performed to the intermediate transfer rolls 22Y, 22M, 22C, and 22K at the secondary transfer position X2. The toner image is secondarily transferred onto the paper P. When the toner image is secondarily transferred, the carrier liquid also moves to the paper P. A secondary transfer voltage (bias voltage) is applied between the intermediate transfer rolls 22Y, 22M, 22C and 22K and the backup rolls 24Y, 24M, 24C and 24K.

  In the image forming apparatus 1, an image is formed as follows.

  First, in the image forming unit 10Y, the photosensitive drum 12Y rotates in the direction indicated by the arrow + R in the drawing, and the surface thereof is charged by the charging device 14Y. Next, the charged surface of the photosensitive drum 12Y is exposed and scanned by the exposure device 16Y, whereby an electrostatic latent image of the first color (Y) is formed on the surface of the photosensitive drum 12Y.

  This electrostatic latent image is developed by the developer supplied by the developing device 18Y, and a visualized toner image is formed on the surface of the photosensitive drum 12Y. The toner image reaches the primary transfer position X1 by the rotation of the photosensitive drum 12Y, and is primarily transferred to the intermediate transfer roll 22Y by applying a primary transfer voltage between the photosensitive drum 12Y and the intermediate transfer roll 22Y. The At this time, the developer carrier liquid also moves to the intermediate transfer roll 22Y.

  The toner image transferred to the intermediate transfer roll 22Y reaches the secondary transfer position X2 by the rotation of the intermediate transfer roll 22Y, and a secondary transfer voltage is applied between the intermediate transfer roll 22Y and the backup roll 24Y. The secondary transfer is performed on the paper P conveyed in the process. At this time, the developer carrier liquid also moves to the paper P.

  Similarly, the second color (M) toner image, the third color (C) toner image, and the fourth color (K) toner image formed by the image forming units 10M, 10C, and 10K are transferred to the intermediate transfer roll 22M. , 22C, and 22K, and sequentially transferred so as to be superimposed on the paper P. The conveyance speed of the paper P and the rotation speed of the photosensitive drums 12Y, 12M, 12C, and 12K are synchronized so that the toner images of the respective colors on the paper P do not shift. As a result, a multiple toner image is formed on the paper P.

  The sheet P on which the multiple toner image has been transferred is conveyed toward the fixing device 30 described in detail below, and the multiple toner image is fixed on the sheet P by a heating and pressing process to be a permanent image.

  The surfaces of the photoconductive drums 12Y, 12M, 12C, and 12K after the primary transfer of the toner images to the intermediate transfer rolls 22Y, 22M, 22C, and 22K are cleaned by a photoconductive drum cleaner (not shown). The remaining developer is removed. Further, the surfaces of the intermediate transfer rolls 22Y, 22M, 22C, and 22K after the secondary transfer of the toner image to the paper P are also cleaned by an intermediate transfer roll cleaner (not shown), and the developer remaining on the surface is removed. Is done.

  When a single color image is formed on a sheet, for example, when a black (K) image is formed, only the toner image formed by the image forming unit 10K is transferred onto the sheet P via the intermediate transfer roll 22K. As described above, the other image forming units 10Y, 10M, and 10C are retracted (separated) from the intermediate transfer rolls 22Y, 22M, and 22C.

(Fixing device of first embodiment)
The fixing device 30 according to the first embodiment includes a carrier liquid reducing unit 32 and a fixing unit 34 as an example of a fixing unit disposed on the downstream side of the carrier liquid reducing unit 32 in the conveyance direction of the paper P. ing.

  The carrier liquid reducing unit 32 includes a heating roll 36 as an example of a heating unit that rotates as the paper P is transported, a removal blade 38 as an example of a removing unit that is in contact with the heating roll 36, and the transport direction of the paper P The removing roll 40 as an example of contact removing means that is in contact with the paper P on the downstream side of the heating roll 36 and the removing roll 40 and the heating roll 36 on the upstream side of the removing blade 38 in the rotation direction of the heating roll 36. A transition roll 42 as an example of the transition means, and a transition assist blade 44 that is in contact with the transition roll 42 in the vicinity of a portion where the transition roll 42 and the heating roll 36 are in contact with each other.

The heating roll 36 has a heat source 45 therein, and the temperature of the outer peripheral surface is adjusted so as to be a predetermined temperature within a range of 100 ° C. to 160 ° C. The heating roll 36 rotates in the direction indicated by the arrow + R while heating the paper P wound around the outer peripheral surface thereof. Specifically, the heating roll 36 rotates while contacting the paper P on the surface (back surface Pb) opposite to the surface (front surface Pa) on which the toner image of the paper P is formed, and the back surface Pb. The sheet P is heated from the beginning. In other words, the paper P is wound around the outer circumferential surface of the heating roll 36 by half a turn and conveyed so that it is heated, while being heated by the heating roll 36 for a half turn.
The temperature of the outer peripheral surface of the heating roll 36 is appropriately set to a level necessary and sufficient to preliminarily heat the paper P prior to the fixing unit 34 at the subsequent stage. The same applies to the contact length between the heating roll 36 and the paper P, and a configuration in which the paper P is heated by winding the paper P around the outer peripheral surface of the heating roll 36 for more than a half circumference may be employed as necessary.

  The removal blade 38 is made of, for example, an elastic material such as a rubber material. The tip of the removal blade 38 is in contact with the outer peripheral surface of the heating roll 36, thereby scraping and heating the carrier liquid adhering to the outer peripheral surface of the heating roll 36. The carrier liquid is removed from the roll 36. A storage tray 46 for storing the carrier liquid scraped from the heating roll 36 is disposed below the removal blade 38.

  The removal roll 40 is made of a material capable of adsorbing a liquid such as a carrier liquid, such as rayon nonwoven fabric, polypropylene, polyethylene, coconut shell activated carbon, EVA resin, and PET nonwoven fabric, and the outer peripheral surface thereof is a toner of the paper P. The back surface Pb on which the image is not formed is in contact with the sheet P and rotates while in contact with the sheet P, thereby adsorbing the carrier liquid floating on the back surface Pb of the sheet P and removing the carrier liquid from the sheet P as will be described later. .

  The transfer roll 42 is made of a material superior in the carrier liquid adsorbability compared to the removal roll 40, and the outer peripheral surface thereof is in contact with the removal roll 40 and the heating roll 36. The removal roll 40 and the heating roll The carrier liquid adsorbed on the removing roll 40 is transferred to the heating roll 36 by rotating while contacting the 36.

The transition auxiliary blade 44 is made of, for example, an elastic material such as a rubber material, and a tip portion thereof is in contact with the transition roll 42 in the vicinity of a portion where the transition roll 42 and the heating roll 36 are in contact with each other. The carrier liquid is scraped from 42, and the carrier liquid is made to stay in the vicinity of the part where the transfer roll 42 and the heating roll 36 are in contact with each other, thereby assisting the transfer of the carrier liquid from the transfer roll 42 to the heating roll 36. .
The removal roll 40, the transfer roll 42, and the removal blade 38 are separated from the heating roll 36 and the paper P at a timing when image formation is not performed, and the attached carrier liquid is removed by a cleaner (not shown).

  The fixing unit 34 includes a plurality of (for example, six) fixing units 52 in which the fixing roll 48 and the pressing roll 50 are arranged to face each other. The plurality of fixing units 52 are arranged along the conveyance direction of the paper P. Each fixing roll 48 has a built-in heat source 54. Each pressing roll 50 is urged toward the fixing roll 48 by an urging member (not shown). The paper P is transported between the fixing roll 48 and the pressure roll 50 to be heated and pressurized, and the toner present on the paper P is fixed to the paper. The reason why the fixing unit 34 includes a plurality of fixing units 52 is to adjust the toner fixing property by making it possible to independently set the conditions of the heat and pressure processing in each fixing unit 52. is there.

  In the paper P, there is carrier liquid that has been transferred from the developing devices 18Y, 18M, 18C, and 18K through the photosensitive drums 12Y, 12M, 12C, and 12K and the intermediate transfer rolls 22Y, 22M, 22C, and 22K. The reducing unit 32 removes a part of the carrier liquid present on the paper P in a liquid state, thereby reducing the carrier liquid present on the paper P.

  FIG. 2 is a diagram for explaining the behavior of the carrier liquid present on the paper P when the paper P is heated by the heating roll 36 of the carrier liquid reducing unit 32.

  FIG. 2A schematically shows a state when the toner image is transferred to the paper P by the transfer devices 20Y, 20M, 20C, and 20K. In the figure, symbol T represents toner, symbol K represents carrier liquid, and symbol W represents moisture inherent in the paper. The toner T adheres to the front surface Pa of the paper P in a state where two layers are stacked. The carrier liquid K and moisture W are present inside the paper P.

  FIG. 2B schematically shows a state when the paper P starts to be heated by the heating roll 36. The toner T is heated to a temperature equal to or higher than the flow start temperature and equal to or lower than the melting point by heating of the heating roll 36 and is in a semi-molten state (in the drawing, the state where the toner T is solidified is indicated by hatching, and the semi-melt Is indicated by a dot). Moisture W present on the paper P expands due to the heating of the heating roll 36 and starts to vaporize.

  FIG. 2C schematically shows a state when the heating of the paper P by the heating roll 36 has progressed. The moisture vaporized by the heating of the heating roll 36 is moved so that the carrier liquid K present on the paper P is pushed out toward the front surface Pa and the back surface Pb of the paper P while being in a liquid state. That is, the carrier liquid K is moved to the front surface Pa and the back surface Pb of the paper P, and is in a state where it floats on the front surface Pa and the back surface Pb of the paper P.

  FIG. 3 shows the relationship between the ratio of the carrier liquid K that floats on the front surface Pa and the back surface Pb of the paper P and the set temperature of the heating roll 36.

  When the paper P is heated from the back surface Pb where the toner image is not formed by the heating roll 36, the carrier liquid that floats on the back surface Pb rather than the carrier liquid K that floats on the front surface Pa of the paper P as shown in FIG. K is more. Further, the ratio of the carrier liquid K that floats on the back surface Pb of the paper P increases as the set temperature of the heating roll 36 increases.

  FIG. 4 shows a transfer mode of the carrier liquid K in the carrier liquid reduction unit 32.

  As shown in FIG. 4, the paper P is gradually heated by being conveyed while being in contact with the heating roll 36, and when the paper P reaches the vicinity of the top of the heating roll 36, the paper P reaches the front surface Pa of the paper P. The carrier liquid K begins to emerge. The toner T also changes from a solidified state to a semi-molten state. The carrier liquid K that has floated on the front surface Pa of the paper P returns to the inside of the paper P when the paper P begins to cool down on the downstream side of the removal roll 40 in the transport direction. The toner T also solidifies again when it begins to cool.

  On the other hand, the carrier liquid K emerges from the back surface Pb of the paper P at a position where the paper P separates from the heating roll 36, and a part of the carrier liquid K that emerges from the back surface Pb adheres to the heating roll 36 and is removed from the heating roll 36. Move towards.

  The carrier liquid K remaining on the back surface Pb of the paper P without moving to the heating roll 36 is adsorbed by the removal roll 40 and removed from the back surface Pb of the paper P. The carrier liquid K adsorbed by the removing roll 40 is transferred to the heating roll 36 through the transfer roll 42. The transfer assist blade 44 scrapes the carrier liquid K from the transfer roll 42 and makes the carrier liquid K easily stay in the vicinity of the portion where the transfer roll 42 and the heating roll 36 are in contact with each other. The transfer of the carrier liquid K to 36 is urged.

  The carrier liquid K transferred to the heating roll 36 is scraped off by the removal blade 38 on the downstream side of the transfer roll 42 in the rotation direction of the heating roll 36 and is removed from the heating roll 36.

  As described above, in the fixing device 30, the carrier liquid K floating on the back surface Pb of the paper P is removed by the carrier liquid reducing unit 32, and the carrier liquid K present on the paper P is reduced. Then, after the carrier liquid K present on the paper P is reduced, the toner T is fixed on the paper P in the fixing unit 34.

  FIG. 5 is a graph showing the relationship between the fixing strength grade of the toner T fixed by the fixing device 30 and the set temperature of the fixing unit 34 (hereinafter simply referred to as “fixing unit set temperature”). When the carrier is reduced (i.e., heating the heating roll 36) and when the carrier liquid reduction unit 32 is not operated (i.e., the heating roll 36 is not heated) and the carrier is not reduced. Is shown in comparison.

  The fixing strength grade defines a standard for evaluating the cohesiveness between the toners T. The smaller the numerical value of the fixing strength grade, the better the cohesiveness between the toners T, and the better the fixing property. Specifically, the fixing strength grade is determined on the basis of the image missing width in the bent portion after the sheet P on which the solid image is fixed is bent and the bent portion is pressed with a predetermined pressure. For example, when the missing width is 0 mm, the fixing strength grade is G0, when the missing width is 0.1 mm, the fixing strength grade is G20, and when the missing width is 0.2 mm, the fixing strength grade is G40. Is 0.4 mm, the fixing strength grade is G60, when the missing width is 0.6 mm, the fixing strength grade is G80, and when the missing width is 0.8 mm, the fixing strength grade is G110, and the missing width is 1. In the case of 0.0 mm, the fixing strength grade is G160.

  As shown in FIG. 5, when the carrier is reduced in each temperature range of the fixing unit set temperature, the fixing strength grade is small, the cohesion between the toners T is good, and the fixing property is excellent. . When carrier reduction is performed, particularly when the fixing unit set temperature is in the range of 80 ° C. to 110 ° C., the result exceeds the target value of G40.

  When the carrier liquid K existing on the paper P is not reduced without operating the carrier liquid reduction unit 32, the toner T is fixed in the fixing unit 34 with the carrier liquid K interposed between the toners T. Therefore, the cohesiveness between the toners T is not good, and the fixing property is deteriorated. On the other hand, when the carrier liquid reduction unit 32 is operated to reduce the carrier liquid K present on the paper P, the fixing of the toner T is performed in the fixing unit 34 without the carrier liquid K being interposed between the toners T. Therefore, the cohesiveness between the toners T is improved, and the fixing property is improved.

  FIG. 6 is a graph showing the relationship between the tape peeling level of the toner T fixed by the fixing device 30 and the fixing unit set temperature. When the carrier liquid is reduced by operating the carrier liquid reducing unit 32, the carrier liquid is reduced. The case where the part 32 is not operated and the carrier is not reduced is shown in comparison.

  The tape peeling level defines a standard for evaluating the adhesion between the toner T and the paper P. The tape peeling level indicates that the larger the value, the better the adhesion between the toner T and the paper P, and the better the fixing property. Specifically, the tape peeling level is determined on the basis of the degree of peeling of the solid image when the adhesive tape is applied to the paper P on which the solid image is fixed and then peeled off. For example, the tape peeling level is L6 when not peeling at all, the tape peeling level is L5 when peeling in the form of dots, and the tape peeling level is L4 when the peeling is granular, and the area is 20% or more and less than 50%. When peeling, the tape peeling level is L3, when the area of 50% or more and less than 80% peels, the tape peeling level is L2, when the area of 80% or more and less than 10% peels, the tape peeling level is L1 When 100%, i.e., all peel, the tape peel level is L0.

  As shown in FIG. 6, when the carrier is reduced in each temperature range of the fixing unit set temperature, the tape peeling level is larger, the adhesion between the toner T and the paper P is better, and the fixing property is higher. Are better. When carrier reduction is performed, the fixing unit set temperature exceeds the target value of L5.5 (tape peeling level between L5 and L6) particularly in the range of 100 ° C. to 110 ° C.

  When the carrier liquid K existing on the paper P is not reduced without operating the carrier liquid reducing unit 32, the fixing of the toner T is performed in the fixing unit 34 with the carrier liquid K interposed between the toner T and the paper P. Therefore, the adhesion between the toner T and the paper P is not good, and the fixing property is deteriorated. On the other hand, when the carrier liquid reduction unit 32 is operated to reduce the carrier liquid K present on the paper P, the toner in the fixing unit 34 without the carrier liquid K being interposed between the toner T and the paper P. Fixing of T is easy to be performed, so that the adhesion between the toner T and the paper P is improved, and the fixing property is improved.

  If the carrier liquid K existing in the paper P is not reduced without operating the carrier liquid reducing unit 32, the toner image is formed on the paper when the fixing unit 34 fixes the toner T at a fixing unit set temperature of 100 ° C. or higher. A phenomenon of reverse transition from the side to the fixing roll side (so-called offset phenomenon) occurs. On the other hand, when the carrier liquid reduction unit 32 is operated to reduce the carrier liquid K existing on the paper P, the offset phenomenon will not occur even if the fixing unit 34 fixes the toner T at a fixing unit set temperature of 100 ° C. or higher. Does not occur.

  As described above, in the fixing device 30, the carrier liquid K existing in the paper P is reduced in the carrier liquid reducing unit 32 and then the toner T is fixed on the paper P in the fixing unit 34. Fixability can be improved. Therefore, in the image forming apparatus 1 including the fixing device 30, an image having excellent fixing properties is formed on the paper P.

  Further, the carrier liquid K adhering to the heating roll 36 that heats the paper P while being in contact with the paper P is removed from the heating roll 36 by the removal blade 38, so that the carrier liquid K adhering to the heating roll 36 is again applied to the paper P. Since it does not adhere, the carrier liquid K present on the paper P is efficiently removed.

  Further, since the removing liquid 40 is brought into contact with the paper P and the carrier liquid K floating on the back surface Pb of the paper P is directly removed from the paper P, the carrier liquid K present on the paper P is more efficiently removed. .

  Further, by bringing the removal roll 40 into contact with the back surface Pb with which the heating roll 36 of the paper P comes into contact, the carrier liquid K that largely floats on the back surface Pb of the paper P is removed. More efficiently removed.

  Further, since the carrier liquid K removed by the removal roll 40 by the transfer roll 42 is transferred to the heating roll 36, the carrier liquid K removed by the removal roll 40 is removed together with the carrier liquid K adhering to the removal roll 40. The blade 38 can be removed all at once.

  In the fixing device of the first embodiment, the removing blade 38 is used as a removing means. In short, it is sufficient that the carrier liquid K adhering to the heating roll 36 can be removed. For example, a belt-like fiber such as polyester or rayon is used. You may comprise so that the carrier liquid K may be wiped off with a body (cleaning web).

  In the fixing device of the first embodiment, the removing roll 40 is used as the contact removing unit. In short, it is only necessary to remove the carrier liquid K that has floated on the back surface Pb of the paper P. For example, polyester, rayon, etc. You may comprise so that the carrier liquid K may be wiped off with a strip | belt-shaped fiber body (cleaning web). In this case, the transfer roll 40 may be removed.

(Fixing device of the second embodiment)
A fixing device 60 according to the second embodiment will be described.

  FIG. 7 shows the configuration of the image forming apparatus 1 having the fixing device 60 of the second embodiment. The fixing device 60 of the second embodiment is different from the fixing device 30 of the first embodiment in that the carrier liquid reducing unit 32 of the fixing device 30 of the first embodiment is changed to a carrier liquid reducing unit 62.

  As illustrated in FIG. 7, the carrier liquid reduction unit 62 of the fixing device 60 according to the second embodiment includes a heating plate 64 as an example of a heating unit that does not move with the conveyance of the paper P, and heating in the conveyance direction of the paper P. It includes a removing unit 66 as an example of a removing means disposed on the downstream side of the plate 64.

  The heating plate 64 has a semi-cylindrical shape and has a heat source 68 therein. The temperature of the outer peripheral surface of the heating plate 64 is adjusted by the heat source 68 so as to be a predetermined temperature within a range of 100 ° C. to 160 ° C. The sheet P is wound around the outer peripheral surface of the heating plate 64, and the sheet P is placed on the heating plate 64 on the surface (back surface Pb) opposite to the surface on which the toner image is formed (front surface Pa). It is contacted and heated from the back surface Pb. In other words, the paper P is wound around the outer peripheral surface of the heating plate 64 and conveyed so as to be folded, and is heated while being conveyed along the outer peripheral surface of the heating plate 64.

  The removal unit 66 includes a removal roll 72 provided so as to contact the paper P in the vicinity of the downstream edge portion 70 in the conveyance direction of the paper P of the heating plate 64, an intermediate roll 74 that contacts the removal roll 72, and an intermediate A removal blade 76 that contacts the roll 74 is included.

  The removal roll 72 is made of a material capable of adsorbing liquids including the carrier liquid K, such as rayon nonwoven fabric, polypropylene, polyethylene, coconut shell activated carbon, EVA resin, and PET nonwoven fabric, and the outer peripheral surface of the paper P The carrier liquid K is in contact with the back surface Pb side where the toner image is not formed, and rotates while contacting the paper P, thereby adsorbing the carrier liquid K floating on the back surface Pb of the paper P and removing the carrier liquid K from the paper P. .

  The intermediate roll 74 is made of a material superior in the adsorptivity of the carrier liquid K compared to the removal roll 72, and the outer peripheral surface thereof is in contact with the removal roll 72 and rotates while being in contact with the removal roll 72. The carrier liquid K adsorbed by the removal roll 72 is transferred to itself.

  The removal blade 76 is made of, for example, an elastic material such as a rubber material, and the carrier liquid K adsorbed on the outer peripheral surface of the intermediate roll 74 is removed by contacting the tip of the removal blade 76 with the outer peripheral surface of the intermediate roll 74. The carrier liquid K is removed from the scraping intermediate roll 74. A storage tray 78 for storing the carrier liquid K scraped off from the intermediate roll 74 is disposed below the removal blade 76.

  FIG. 8 shows a transfer mode of the carrier liquid K in the carrier liquid reduction unit 62.

  As shown in FIG. 8, the paper P is gradually heated by being conveyed while being in contact with the heating plate 64, and when the paper P reaches the vicinity of the top of the heating plate 64, the paper P reaches the front surface Pa of the paper P. The carrier liquid K begins to emerge. The toner T also changes from a solidified state to a semi-molten state. The carrier liquid K that has floated on the front surface Pa of the paper P returns to the inside of the paper P when the paper P begins to cool down on the downstream side of the removal roll 72 in the transport direction. The toner T also solidifies again when it begins to cool.

  On the other hand, the carrier liquid K emerges from the back surface Pb of the paper P at a position where the paper P is separated from the heating plate 64. The carrier liquid K that floats on the back surface Pb of the paper P is adsorbed by the removal roll 72 and removed from the back surface Pb of the paper P. Further, the carrier liquid K that has floated on the back surface Pb of the paper P adheres to the edge portion 70 of the heating plate 64, but the removal roll 72 is provided in the vicinity of the edge portion 70 of the heating plate 64. The carrier liquid K adhering to the part 70 is also removed by the removing roll 72.

  The carrier liquid K adsorbed by the removing roll 72 is transferred to the intermediate roll 74. The carrier liquid K transferred to the intermediate roll 74 is scraped off by the removal blade 76 and removed from the intermediate roll 74.

  As described above, the carrier liquid reducing unit 62 of the fixing device 60 removes the carrier liquid K that floats on the back surface Pb of the paper P, thereby reducing the carrier liquid K present on the paper P.

  As described above, in the fixing device according to the second embodiment, the removal roll is provided in the carrier liquid reducing unit 62 so as to be in contact with the paper P in the vicinity of the edge 70 of the heating plate 64, and is provided on the back surface Pb of the paper P. By removing the carrier liquid K that has been lifted directly from the paper P and removing the carrier liquid K adhering to the edge 70 of the heating plate 64 from the heating plate 64, the carrier liquid K present on the paper P is more efficiently removed. The

  As shown in FIG. 9, the heating plate 64 is provided with an opening 80, and the removal blade 82 whose one end is in contact with the back surface Pb of the desired sheet P from the opening 80 and whose other end is in contact with the intermediate roll 74 is The carrier liquid K that has come out on the back surface Pb of the metal plate and the carrier liquid K that adheres to the edge 84 of the opening 80 of the heating plate 64 may be removed.

  In the fixing device 60 of the second embodiment, the removing unit 66 is used as a removing unit. In short, the carrier liquid K that has floated on the back surface Pb of the paper P is removed and attached to the edges 70 and 84 of the heating plate 64. The carrier liquid K may be removed as long as the carrier liquid K can be removed. For example, the carrier liquid K may be wiped with a belt-like fiber body (cleaning web) such as polyester or rayon.

1 Image forming apparatus 10Y, 10M, 10C, 10K Image forming unit 12Y, 12M, 12C, 12K Photosensitive drum (an example of an image carrier)
14Y, 14M, 14C, 14K Charging devices 16Y, 16M, 16C, 16K Exposure devices 18Y, 18M, 18C, 18K Developing devices 20Y, 20M, 20C, 20K Transfer device 30 Fixing device 32 Carrier liquid reduction unit 34 Fixing unit (fixing means) Example)
36 Heating roll (an example of heating means)
38 Removal blade (an example of removal means)
40 removal roll (an example of contact removal means)
42 Transition roll (an example of transition means)
60 Fixing Device 62 Carrier Liquid Reduction Unit 64 Heating Plate (Example of Heating Unit)
66 Removal unit (an example of removal means)
70 edge

Claims (6)

The recording is performed such that the carrier liquid present on the recording medium is moved from the inside of the recording medium to the surface by contacting the recording medium onto which the toner image obtained by developing with a developer containing toner and carrier liquid is transferred. Heating means for heating the medium;
Removing means for removing the carrier liquid adhering to the heating means from the heating means;
A fixing unit disposed on the downstream side of the heating unit in the conveyance direction of the recording medium and fixing the toner present on the recording medium to the recording medium;
A fixing device. The removing means is arranged on the side where the heating means is provided with respect to the conveyance surface of the recording medium,
Contact removing means for removing, from the recording medium, carrier liquid that has contacted the surface of the recording medium that contacts the heating means and moved to the surface of the recording medium;
The fixing device according to claim 1.   The fixing device according to claim 2, wherein the contact removing unit is in contact with a surface side of the recording medium that is in contact with the heating unit and on which the toner image is not formed. Furthermore, a transfer means for transferring the carrier liquid removed by the contact removal means to the heating means,
The fixing device according to claim 2, wherein the removing unit removes the carrier liquid transferred by the transferring unit. The heating means is composed of a heating plate that contacts the surface of the recording medium on which the toner image is not formed and does not move along with the conveyance of the recording medium,
The removing means also serves as the contact removing means, and is provided so as to come into contact with the surface side of the recording medium that contacts the heating plate, and adheres to the downstream edge of the heating plate in the conveyance direction of the recording medium. The fixing device according to claim 3, wherein the carrier liquid is removed from the heating plate, and the carrier liquid that has moved to the surface of the recording medium is removed from the recording medium. An image carrier on which an electrostatic latent image is formed;
A developing device for developing the electrostatic latent image formed on the image carrier with a developer having toner and carrier liquid;
A transfer device for transferring the toner image developed by the developing device to a recording medium;
The fixing device according to claim 1, wherein the toner image transferred to the recording medium by the transfer device is fixed to the recording medium.
An image forming apparatus comprising: