JP2008122719A - Image heating device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image heating device capable of restraining slip caused by dew condensation between paper and a pressure rotating body which forms a pressure nip part with a fixing rotating body without deteriorating the pressure rotating body, and capable of preventing the occurrence of paper jamming, associated with the slip, and an image forming apparatus equipped with the image heating device. <P>SOLUTION: The image heating device 11 has the fixing rotating body 30 equipped with a heating means, and the pressure rotating body 34 pressured to the fixing rotating body 30 and driven to rotate, and heats an image T by making the paper P carrying the image T pass through the pressure nip part N formed by the fixing rotating body 30 and the pressure rotating body 34, and is equipped with a water absorbing member 21 for absorbing moisture on the surface of the pressure rotating body. The water absorbing member 21 abuts on or separates from the surface of the pressure rotating body according to the condition of the conveyed paper P. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image heating apparatus used for heating a toner image in an image forming apparatus such as a copying machine, a laser printer, and a facsimile machine, and an image forming apparatus including such an image heating apparatus.

  That is, a toner image is formed on the image carrier by using image forming process means such as electrophotography, electrostatic recording, magnetic recording, or the like using toner made of heat-meltable resin or the like corresponding to the image information. This unfixed toner image is carried on the surface of paper (paper, printing paper, paper sheet, OHT sheet, glossy paper, glossy film, etc.) by the direct transfer method or the indirect transfer method, and the unfixed toner image is placed on the paper surface. A heat fixing process is performed as a permanently fixed image. The present invention relates to such an image heating apparatus, and further relates to an image forming apparatus such as an electrophotographic apparatus and an electrostatic recording apparatus provided with such an image heating apparatus.

  Conventionally, for example, in a printer using an electrophotographic process, a toner image (unfixed image) based on an image signal from a personal computer or the like is electrostatically carried on a sheet, and this is heated and pressed by a fixing device. Thus, the toner image was fixed on the paper. As an image heating apparatus used for such a fixing device of an electrophotographic process, there are apparatuses shown in FIGS. 20 and 21, for example.

  FIG. 20 is a schematic cross-sectional view of an image heating device as a fixing device, and FIG. 21 is a view as seen from the paper feeding side (J direction in FIG. 20) of the same device.

  In this example, the image heating apparatus includes a heater unit 100 as a fixing rotator having a built-in heating means. The heater unit 100 includes a ceramic heater 101 that generates heat when energized, a heat-resistant cylindrical fixing film 102, a film guide 103, a stay material 104, a flange 105, and the like. The film guide 103 holds the ceramic heater 101 and guides the rotation of the fixing film 102.

  The pressure roller 106 as a pressure rotator is formed of a cored bar 114 and an elastic rubber part 115 provided on the outer periphery thereof.

  The heater unit 100 and the pressure roller 106 are pressed against each other with a predetermined pressure by a pressure unit (not shown). A paper discharge roller pair 107 including a paper discharge roller 108 and a paper discharge roller 109 is housed in the fixing device casings 110 and 113. An entrance guide 112 is provided on the upstream side of the casing 110 in the sheet conveyance direction.

  The pressure roller 106 receives a driving force from a main motor in the printer body via a pressure roller gear 116 shown in FIG. 21, and rotates in the direction of arrow a in FIG. The fixing film 102 rotates.

  On the other hand, the ceramic heater 101 is supplied with electric power through a temperature control circuit (not shown), and the supplied electric power is adjusted so as to reach a predetermined temperature (fixing temperature).

  As described above, the sheet P on which the unfixed image is transferred is transferred between the heater unit 100 and the pressure roller 106 in a state where the pressure roller 106 and the fixing film 102 are rotated and the ceramic heater 101 is heated to a predetermined temperature. It is introduced into a pressure nip portion (that is, a fixing nip portion) N. Next, the paper P is conveyed in a state of being in close contact with the fixing film 102. As a result, heat from the ceramic heater 101 via the fixing film 102 and pressure contact pressure between the heater unit 100 and the pressure roller 106 are applied to the paper P, and the toner image is fixed on the paper by heat and pressure.

  Then, the paper P after passing through the pressure nip is conveyed to the output side by a paper discharge roller pair 107 including a paper discharge roller 108 and a paper discharge roller 109.

  However, the image heating apparatus described above has the following problems.

  The pressure roller 106 is rotationally driven, and the fixing film 102 is driven to rotate. Therefore, the resistance force R1 (sliding resistance with the film guide 103), R2 (sliding resistance with the ceramic heater 101), R3 (sliding resistance with the guide surface of the flange 105) of the portion where the fixing film 102 slides. ) Is generated. Accordingly, in order to transport the paper P, the relationship with the transport force F1 applied to the paper P from the pressure roller 106 is set to satisfy F1> F2.

  However, when printing first in the morning (between the first 10 sheets of continuous printing) and the like, the sheet is conveyed with the temperature of the pressure roller 106 still low. Therefore, when a large amount of water is contained in the paper P, the water contained in the paper P evaporates by the heating by the ceramic heater 101 and condenses on the surface of the pressure roller 106, and the pressure roller The coefficient of friction of 106 decreases. As a result, the relationship between the sliding resistance F2 and the conveying force F1 becomes F1 <F2, and a situation occurs in which the paper slips (hereinafter referred to as “condensation slip”). As a result, the conveyance speed at the nip portion N becomes slower than the conveyance speed at the image forming portion, so that the sheet P is slackened, the unfixed image surface is rubbed against a member near the conveyance path, or in the worst case. The paper is not conveyed by the pressure roller 106 and leads to occurrence of a paper jam (hereinafter referred to as “jam”).

  In addition, when the fixing film 102 is not sufficiently charged to the minus side or when the pressure roller 106 is charged to the minus side, the toner on the negatively charged paper P adheres to the fixing film 102. That is, electrostatic offset occurs. Therefore, the toner is offset to the surface of the pressure roller 106 after the paper P has passed. As a result, as described above, the friction coefficient of the pressure roller 106 decreases to cause a slip, or when the next sheet is fixed, the surface on the side of the pressure roller 106 opposite to the image surface of the sheet is formed. The problem of smearing with toner arises.

In order to solve the above problem, as disclosed in Patent Document 1, for example, by providing a water absorbing member or a cleaning member in contact with the surface of the pressure roller, dew slip or jam of the pressure roller, or pressure It has been proposed to prevent roller contamination. It has also been proposed to prevent wear of the pressure roller and contamination of the water absorption member or cleaning member by separating the water absorption member or cleaning member in accordance with the temperature rise of the pressure roller.
JP 2000-221813 A

  However, only the configuration of the invention as disclosed in the above-described patent document cannot satisfy all of the condensation slip, wear, and deterioration of the pressure roller.

  In other words, with respect to the water absorbing member (cleaning member) that contacts the pressure roller in order to suppress condensation slip, the water absorbing member (cleaning member) is separated from the pressure roller at an earlier stage except when necessary. It is obvious that it is good against deterioration and dirt. However, it has been difficult to make contact at a pinpoint when necessary.

  For example, in the case of the configuration in which the water absorbing member (cleaning member) is separated in accordance with the increase in the surface temperature of the pressure roller as in the invention disclosed in the above-mentioned patent document, there are the following problems.

  In other words, even when the pressure roller surface temperature rises and becomes high, if a sheet containing moisture (moisture absorbing paper) is conveyed, a large amount of moisture evaporates in the fixing nip, resulting in the pressure roller surface. Water drops will adhere. At this time, since the water absorbing member (cleaning member) is not in contact with the pressure roller, water droplets remain on the surface of the pressure roller, which may cause jamming due to the above-described condensation slip.

  On the contrary, when a paper (dry paper) containing almost no moisture is conveyed in a state where the temperature of the pressure roller is low, the water absorbing member (cleaning member) is formed although there is almost no condensation on the surface of the pressure roller. ) Will be brought into contact with the pressure roller more than necessary. This promotes wear on the surface of the pressure roller and shortens the service life.

  In particular, it has already been found that the pressure roller wear due to contact with the water-absorbing member is larger when the pressure roller surface is not condensed and is in a normal dry state. This is presumed that when water is adhered to the pressure roller surface, the sliding property of the water absorbing member (cleaning member) in contact is improved. In addition, the fact that the water absorbing member (cleaning member) is always in contact means that the water absorbing member (cleaning member) is also in contact when the rotation starts from the pressure roller stationary state. In this case, when the rotation is started in the cold state, the solidified dirt in the vicinity of the pressure roller contact portion may be discharged at a stretch and adhere to the conveyed paper. In addition, being always in contact means that the saturation time with respect to the dirt of the water absorbing member (cleaning member) is advanced, and as a result, the conveyed paper is soiled.

  As described above, in the conventional configuration, it is very difficult to achieve both the slip accompanying the condensation on the surface of the pressure roller and the deterioration and dirt on the surface of the pressure roller due to the contact with the water absorbing member.

  An object of the present invention is to suppress the condensation slip generated between the pressure rotator and the sheet without deteriorating the pressure rotator forming the pressure nip portion with the fixing rotator, and accompanying this. An object of the present invention is to provide an image heating apparatus capable of preventing occurrence of a paper jam (jam) and an image forming apparatus provided with such an image heating apparatus.

The above object is achieved by an image heating apparatus according to the present invention and an image forming apparatus provided with such an image heating apparatus. In summary, according to the first aspect of the present invention, there is provided a fixing rotator provided with a heat generating means, and a pressure rotator that is rotationally driven and pressed against the fixing rotator, In an image heating apparatus that heats the image by passing a sheet carrying an image through a pressure nip formed by the pressure rotator,
An image comprising a water absorbing member for absorbing moisture on the surface of the pressurizing rotator, wherein the water absorbing member contacts and separates from the surface of the pressurizing rotator depending on the state of the sheet being conveyed. A heating device is provided.

  According to the second aspect of the present invention, in the image forming apparatus comprising: an image forming unit that forms an unfixed toner image on a sheet; and a fixing device that fixes the unfixed toner image on the sheet. An image forming apparatus is provided that is the image heating apparatus.

  ADVANTAGE OF THE INVENTION According to this invention, the water | moisture content adhering to the pressurization rotary body surface in the vicinity of a pressurization nip can be absorbed, a dew condensation slip can be suppressed, and generation | occurrence | production of jam can be prevented. In addition, since the water absorbing member is not brought into contact with the pressure rotator more than necessary during normal conveyance, it is possible to extend the life of the surface of the pressure rotator and prevent the water absorbing member itself from being contaminated.

  Hereinafter, an image heating apparatus and an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Example 1
FIG. 1 shows a schematic configuration of an embodiment of an image forming apparatus according to the present invention.

  In this embodiment, the image forming apparatus of the present invention includes a drum-type electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) 1 as an image carrier constituting an image forming unit. The photosensitive drum 1 is rotationally driven at a predetermined process speed (PS), for example, PS = 200 mm / sec, in a direction indicated by an arrow (clockwise in FIG. 1) by a main body drive motor (not shown) that is a drive unit.

  Further, as an image forming unit, a charging roller 2 as a charging device, an exposure device 3, a developing device 4, a transfer roller 5 as a transfer device, and a cleaning device are sequentially provided around the photosensitive drum 1 along the rotation direction. The cleaning blade 6 is disposed.

  A paper feeding cassette 7 that stores paper P such as paper as a recording material is disposed at the lower part of the apparatus main body. Further, the paper feeding roller 15, the transporting roller 8, the top sensor 9, the photosensitive drum 1 and the transfer roller 5, the transporting guide 10, the fixing device 11, and the paper discharging roller are sequentially arranged from the paper feeding cassette 7 along the transporting path of the paper P. 13 and a paper discharge tray 14 are arranged.

  In this image forming apparatus, the permissible range of the basis weight of the paper P is 60 g to 100 g.

  Next, the operation of the image forming apparatus having the above configuration will be described.

  The photosensitive drum 1 that is rotationally driven in the direction of the arrow by a main body drive motor (not shown) is uniformly charged to a predetermined polarity and a predetermined potential by the charging roller 2. The exposure device 3 is a laser scanner, and outputs a modulated laser beam corresponding to a time-series electric digital pixel signal of target image information input from a host device such as a computer or an image reading device (not shown). The exposure device 3 scans and exposes the surface of the photosensitive drum 1 with this laser light via a folding mirror (not shown). As a result, the charge of the exposed portion is removed from the photosensitive drum 1 to form an electrostatic latent image. The electrostatic latent image is developed by the developing device 4. The developing device 4 has a developing roller 4a. A developing bias is applied to the developing roller 4a to attach toner to the electrostatic latent image on the photosensitive drum 1 and develop (develop) it as a toner image.

  The toner image is transferred onto the paper P by the transfer roller 5. The paper P is stored in the paper feed cassette 7, fed by the paper feed roller 15, transported by the transport roller 8, passes through the top sensor 9, and is transported to the transfer nip portion between the photosensitive drum 1 and the transfer roller 5. The At this time, the leading edge of the paper P is detected by the top sensor 9 and is synchronized with the toner image on the photosensitive drum 1. A transfer bias is applied to the transfer roller 5, whereby the toner image on the photosensitive drum 1 is transferred to a predetermined position on the paper P.

  The sheet P carrying the unfixed toner image on the surface by the transfer is transported along the transport guide 10 to the fixing device 11 as an image heating device, where the unfixed toner is heated and pressurized to be on the sheet P. It is fixed.

  The paper P after the toner image is fixed is discharged onto a paper discharge tray 14 on the upper surface of the apparatus main body by a paper discharge roller 13.

  On the other hand, after the toner image is transferred, the toner remaining on the surface without being transferred to the paper P is removed by the cleaning blade of the cleaning device 6, and the next image formation is performed.

  By repeating the above operation, image formation can be performed one after another.

  Next, details of the fixing device 11 will be described.

  FIG. 2 shows a schematic configuration of the fixing device 11 of the present invention. The fixing device 11 in this embodiment is a film heating type image heating device using a ceramic heater as a heating body.

  The fixing device 11 includes a fixing rotator 30 and a pressure rotator 34 which are in pressure contact with each other to form a pressure nip portion, that is, a fixing nip portion N and rotate. The fixing device 11 holds and conveys the sheet P carrying the unfixed toner image between the fixing rotator 30 and the pressure rotator 34 so that the unfixed toner image contacts the fixing rotator 30 at the nip portion N. The unfixed toner image is fixed on the paper P.

  More specifically, the fixing rotator 30 includes a horizontally long heater stay 31 that is a heat-resistant resin as a heating material support in this embodiment shown in FIG. The heater stay 31 includes a heater 33 that is a heating element as a heat generating means, and serves as a guide member on the inner surface of the following endless film 32 (hereinafter referred to as “film”).

  In other words, the heat-resistant endless film 32 is externally fitted to the heater stay 31. The inner peripheral length of the film 32 and the outer peripheral length of the heater stay 31 including the heater 33 are made larger by about 3 mm, for example. is there. Therefore, the film 32 is loosely fitted to the stay 31 including the heater 33 with a sufficient circumferential length.

  The heater 33, which is a heating element, is screen-printed with an electric resistance material (heating element) such as Ag / Pd (silver palladium) in a thickness of 10 μm and a width of about 1 to 5 mm along substantially the center of the substrate made of alumina or the like. Etc., and coated with glass or fluororesin as a protective layer.

  A pressure roller 34 as a pressure rotator for driving the film 32 forms a pressure nip portion, that is, a fixing nip portion N with the film 2 interposed between the pressure roller 34 and the heater 33. In the present embodiment, the pressure roller 34 is composed of an aluminum pressure roller core 35 and a pressure roller elastic body portion 36 made of silicone rubber that is sheathed on the core shaft 35. Yes. The pressure roller 34 is driven to rotate in the direction of the arrow by driving the end of the pressure roller core 35 by a motor which is a driving means (not shown). When the pressure roller 34 is driven to rotate, the film 32 is also driven to rotate.

  Fixing is a guide member that guides the paper P conveyed by the conveyance guide 10 to the fixing nip N of the fixing device 11 between the fixing nip portion N of the fixing device 11 and the conveyance guide 10 on the upstream side in the paper conveyance direction. An inlet guide 16 is arranged.

  The front end portion of the fixing inlet guide 16 on the conveyance guide 10 side is attached to both ends in the longitudinal direction by a support portion 17 so as to be rotatable by a fixing guide (not shown), and the fixing nip portion N side can be rotated up and down in the conveyance direction. It has become. A spring 22 as an urging member for restricting the vertical movement of the fixing inlet guide 16 is installed at the center.

  A water absorbing felt 21 as a water absorbing member is installed at the front end of the fixing inlet guide 16 on the fixing nip N side. As the water absorbent felt 21 in this embodiment, a non-woven fabric (trade name: Nomex felt) made of aramid fibers having an average diameter of 18 μm and having a thickness of 2.8 mm, a length of 5.0 mm, a width of 217 mm, and a porosity of 82% is used. Details of the operation of the fixing entrance guide 16 will be described later.

  When the film 32 is not driven, the remaining part of the film 32 except for the part sandwiched between the fixing nip N between the heater 33 and the pressure roller 34 is substantially tension free. When the pressure roller 34 is rotationally driven, the film back surface is rotationally driven in the fixing nip portion N in the direction of the arrow while the film back surface slides on the surface of the heater 33 at substantially the same rotational speed as the pressure roller 34. .

  In a state where the film drive and the heater 33 are energized, the sheet carrying the unfixed image is introduced between the film 32 and the pressure roller 34 in the fixing nip portion N with the image carrier surface facing upward. . As a result, the paper passes through the fixing nip portion N together with the film 32, and the heat energy of the heater 33 that is in contact with the back surface of the film in the fixing nip portion N is applied to the paper through the film 2 and the toner image. T is fixed by heat and discharged outside the fixing device.

  Next, the movement of the fixing inlet guide 16 will be described with reference to FIGS.

  FIG. 3 is a schematic diagram simply showing a path from the sheet passing through the transfer roller 5 to the fixing nip portion N after passing through the conveyance guide 10 and the fixing inlet guide 16. When the paper P enters the fixing nip portion N, as shown in FIG. 4, there is a slight sag between the fixing device 11 and the transfer roller 5. In the image forming apparatus main body in this embodiment, speed control is performed with a certain degree of slack so that the sheet P is not pulled between the transfer and fixing so that the printed image does not stretch. ing.

  In FIG. 4, the tangent line E on the sheet conveyance surface (front surface) side of the fixing inlet guide 16 is positioned on the upper side (conveyance side) with respect to the tangent line G connecting the fixing nip portion N and the tip of the conveyance guide 10. Yes.

  Next, FIG. 5 shows that when the moisture-absorbing paper is passed in a low temperature state, the surface of the pressure roller 34 is condensed, and the pressure roller 34 and the paper P slip due to condensation and bend between transfer and fixing. Indicates the state of the hour.

  In FIG. 5, the pressure roller 34 and the paper P slip due to condensation, so that the downward deflection of the paper P reaches the limit between the transfer and fixing, and the fixing inlet guide 16 is moved downward (see FIG. The state of being pushed down in the direction of arrow b) is shown.

  The fixing inlet guide 16 pushed down by the paper P in the same figure is rotated in the direction of the pressure roller 34 with the support portion 17 as a fulcrum, and the fixing nip portion N and the leading end of the conveyance guide 10 To the position of the tangent line G. At this time, the water-absorbing felt 21 is pushed downward in the drawing along with the movement of the fixing inlet guide 16 pushed by the paper P, and comes into contact with the surface of the pressure roller 34. The water absorbent felt 21 that has come into contact with the pressure roller 34 absorbs moisture condensed on the surface of the pressure roller 34, thereby suppressing the condensation slip of the pressure roller 34 and causing the paper P to jam between the transfer and fixing. This makes it possible to carry the paper smoothly.

  Further, for example, as shown in FIG. 6, the sheet P is bent at a stretch due to condensation slip and there is no place between transfer and fixing, and an upper loop (hereinafter referred to as “upper loop”) is generated. is there. Also in this case, if it is plain paper having a general basis weight (60 g or more), the fixing inlet guide 16 is pushed down in the same figure (arrow direction) by the waist of the paper, and the water absorbent felt 21 and the pressure roller 34 can be brought into contact.

  According to this embodiment, for example, when moisture-absorbing paper is passed in a low temperature state, the surface of the pressure roller 34 is condensed near the nip, and condensation slip occurs between the pressure roller 34 and the paper P. In the case, it operates as follows.

  That is, as described above, the fixing inlet guide 16 and the water absorbent felt 21 provided on the fixing inlet guide 16 are brought into contact with the pressure roller 34 according to the pressure of the conveyed paper P. As a result, moisture adhering to the surface of the pressure roller 34 immediately before the fixing nip portion N can be absorbed, and condensation slip can be suppressed, and jamming can be prevented.

  Further, during normal conveyance, the water absorbent felt 21 is not brought into contact with the pressure roller 34 more than necessary, so that it is effective against wear of the pressure roller surface and dirt on the water absorbent felt 21 itself, and has a long life. Can be realized.

  Here, the force with which the paper P pushes the fixing inlet guide 16 differs depending on the paper size and thickness, but the spring force of the spring 22 of the fixing inlet guide 16 fixes the fixing inlet guide 16 with a pressure of about 10 to 60 g. It is set to move to a position of a tangent line G between the nip portion N and the tip of the conveyance guide 10.

  Moreover, although the nonwoven fabric (brand name: Nomex felt) which consists of an aramid fiber was used as a water absorption member in a present Example, for example, what is necessary is just a porous felt like a non-woven processed polyimide, and the whole surface has a density. Those having excellent homogeneity are more preferable.

  In this embodiment, the fixing inlet guide 16 that guides the paper P to the fixing nip portion N is used as a member for providing the water-absorbing felt 21 that is brought into contact with the pressure roller 34. However, the fixing inlet guide 16 is not limited to this. Any member near the nip N may be used.

  In this embodiment, as a means for bringing the water-absorbing felt 21 into contact with the pressure roller 34, the pressure of the paper P against the fixing inlet guide 16 is used. Any device that uses and detects the amount of slack and pressure may be used. One example thereof will be described later in Example 3.

Example 2
A second embodiment of the image heating apparatus according to the present invention will be described. The overall configuration of the image heating apparatus of the present embodiment and the image forming apparatus to which the image heating apparatus is applied have the same configuration as the image heating apparatus and the image forming apparatus described in the first embodiment. Therefore, in the apparatus of the present embodiment, members having the same configuration and function are denoted by the same reference numerals, the description of the first embodiment is used, and the description thereof is omitted here.

  In this embodiment, the member on the downstream side of the fixing nip portion N is operated by the link mechanism as the connecting means in response to the pressing of the sheet P on the upstream side of the fixing nip portion N (that is, the fixing inlet guide side). A configuration for suppressing condensation slip will be described.

  The steam generated at the fixing nip portion N is likely to scatter particularly on the downstream side in the transport direction and on the pressure roller 34 side. This is due to the following reason.

  As shown in FIG. 7, the steam generated in the fixing nip N from the conveyance direction of the paper P and the rotation direction of the pressure roller 34 easily circulates downstream of the fixing nip N. In addition, since the printing surface side on which the toner image T is placed is blocked, it is difficult for the vapor to fly, and the vapor easily circulates to the pressure roller 34 side that is the non-printing surface side.

  Further, since the pressure roller 34 is surrounded by the fixing outlet guide 23 on the downstream side of the nip portion, the steam circulated in the rotation direction of the pressure roller 34 loses the escape place, and finally water droplets are formed on the surface of the pressure roller 34. As a result, condensation slip may occur.

  In such a phenomenon, the higher the process speed, the faster the circulation of the steam, so that the occurrence of dew slip appears more remarkably. In addition, the larger the basis weight of the paper P, the more water is absorbed in the paper, and therefore condensation slip is more likely to occur.

  Therefore, in order to suppress the condensation slip over a long period of time and further to cope with the process speed and the basis weight of the paper, not only the moisture on the surface of the pressure roller 34 is absorbed but also the pressure roller 34. It is necessary to block the flow of steam circulating in the direction of rotation. Thereby, the atmospheric humidity in the vicinity of the pressure roller 34 can be lowered. For this purpose, a configuration that absorbs moisture on the surface of the pressure roller 34 while preventing the flow of steam generated in the fixing nip N, particularly at the downstream side in the conveyance direction of the fixing nip N is desirable.

  Therefore, in the present exemplary embodiment, as illustrated in FIG. 8, a paper discharge separation guide 24 is disposed on the downstream side of the fixing nip portion N in the sheet conveyance direction in the fixing device 11.

  Here, the paper discharge separation guide 24 plays a role of performing conveyance guidance while separating the paper P conveyed from the fixing nip portion N from the pressure roller 34.

  Further, a link mechanism is provided by the fixing inlet guide 16 and the paper discharge separation guide 24, and a water absorbing member is provided in the paper discharge separation guide 24 on the conveyance downstream side of the fixing nip N. With this configuration, it is possible to further suppress condensation slip.

  Next, the link mechanism between the fixing inlet guide 16 and the paper discharge separation guide 24 and the operation thereof will be described in detail.

  First, the fixing inlet guide 16 is fixed at the both ends in the longitudinal direction by the supporting portion 17 by a fixing guide (not shown) as in the first embodiment, and at the both ends in the longitudinal direction of the leading end portion on the fixing nip N side. , Ring receiving portions 18 as shown in FIG. 8 are provided.

  Similarly to the fixing entrance guide 16, the discharge separation guide 24 is fixed at both ends in the longitudinal direction by a fixing guide (not shown) by a support portion 25, and the support portion 25 serves as a fulcrum in the R direction in FIG. It can be rotated. FIG. 8 shows a normal state, which is configured to rotate in the R direction with reference to this position. A water absorbent felt 21 (trade name: Nomex felt) similar to that of the first embodiment is provided at the front end of the discharge separation guide 24 on the pressure roller 34 side.

  Similarly to the fixing entrance guide 16, ring receiving portions 26 are respectively provided at both ends in the longitudinal direction opposite to the side where the water absorbent felt 21 is provided of the paper discharge separating guide 24.

  Further, a hooking member 19 that connects the ring receiving portion 18 of the fixing inlet guide 16 and the ring receiving portion 26 of the paper discharge separating guide 24 constituting a link mechanism as a connecting means at both ends in the longitudinal direction. Are provided. The hooking member 19 has a hooking ring 20 for hooking on the ring receiving part 18 of the fixing inlet guide 16 and the ring receiving part 26 of the paper discharge separating guide 24, respectively. The fixing inlet guide 16 and the paper discharge separating guide 24 are connected. That is, the hooking member 19 is a member for rotating the paper discharge separating guide 24 in accordance with the operation of the fixing inlet guide 16.

  Next, the operation of these link mechanisms will be described in detail.

  In FIG. 9, the pressure roller 34 and the paper P slip due to condensation, so that the downward deflection of the paper P reaches the limit between the transfer and fixing, and the fixing inlet guide 16 is moved downward (see FIG. (b direction) is shown pushed down. When the fixing inlet guide 16 is pushed down, the hooking member 19 connected to the ring receiving portion 18 of the fixing inlet guide 16 moves in the downward direction (arrow direction). The hooking member 19 moved downward together with the fixing inlet guide 16 acts to push the ring receiving portion 26 of the paper discharge separating guide 24 in the H direction in FIG. The discharge separation guide 24 whose center of the cross section is fixed by the support portion 25 rotates in the R direction according to the force in the H direction from the hooking member 19 and is attached to the fixing nip portion N side. The water absorbent felt 21 is in contact with the surface of the pressure roller 34. Further, the steam blocked by the paper discharge separation guide 24 is discharged from the upper downstream side of the paper discharge separation guide 24 to the outside of the fixing device.

  Through a series of these operations, for example, even when moisture-absorbing paper containing a large amount of moisture is passed through in an extremely high humidity environment, the flow of steam circulating toward the pressure roller 34 can be blocked.

  That is, a link mechanism is provided between the fixing inlet guide 16 and the paper discharge separation guide 24, and the paper discharge separation guide 24 is tilted toward the fixing nip portion N in accordance with the pressing of the conveyed paper P to the fixing inlet guide 16. . As a result, the flow of steam circulating toward the pressure roller 34 can be blocked. Further, the total atmospheric humidity in the fixing device accompanying durability can be reduced.

  Further, with the above configuration, the saturation time of the water-absorbing felt 21 that absorbs moisture on the surface of the pressure roller 34 can be greatly extended, and stable dew slip regardless of the durability of the image forming apparatus main body and the sheet passing state. Can be suppressed.

  Furthermore, it is possible to increase the product specifications because it can cope with the increase in process speed. Moreover, it can respond to paper having a basis weight of 100 g or more that absorbs a large amount of water.

(Modified example)
Further, as a method for more reliably preventing condensation slip, for example, as shown in FIG. 10, it is possible to adopt a configuration in which water-absorbing felts 21 are provided in both the fixing inlet guide 16 and the paper discharge separation guide 24.

  By using this configuration, even when the moisture-absorbing paper containing a large amount of moisture is passed through in an extremely high humidity environment, the paper discharge separation guide 24 is located on the downstream side in the conveyance direction near the fixing nip N. The flow of steam in the vicinity of the pressure roller 34 can be blocked. Further, the water absorbing felt 21 provided in the paper discharge separating guide 24 and the fixing inlet guide 16 reliably absorbs moisture on the surface of the pressure roller 34, so that dew condensation slip can be further reliably suppressed. Thereby, the saturation time of the water-absorbing felt 21 that absorbs moisture on the surface of the pressure roller 34 can be further greatly extended, and the life can be further extended.

  That is, as shown in FIG. 11, when the pressure roller 34 and the paper P slip on the condensation, the downward deflection of the paper P between the transfer and fixing reaches a limit, and the fixing entrance guide 16 is moved by the waist of the paper. Push down in the figure. At this time, the water absorbent felt 21 attached to the fixing inlet guide 16 comes into contact with the pressure roller 34. Simultaneously with the movement of the fixing inlet guide 16, the hooking member 19 attached to the ring receiving portion 18 follows and moves downward in the figure. The hooking member 19 moved downward together with the fixing inlet guide 16 acts to push the ring receiving portion 26 of the paper discharge separating guide 24 in the H direction in FIG. The paper discharge separating guide 24 whose center of the cross section is fixed by the support portion 25 rotates in the R direction in accordance with the force from the hooking member 19, and the water absorption attached to the fixing nip portion N side. The felt 21 is in contact with the pressure roller 34.

  These series of operations are performed at the same timing, that is, the water absorbent felt 21 attached to each of the fixing inlet guide 16 and the paper discharge separation guide 24 contacts the surface of the pressure roller 34 at substantially the same timing. Will do.

  FIG. 12 shows a case where the sheet P is bent at a stretch due to condensation slip and an upper loop is generated. In this case, also in this embodiment, as in the first embodiment, if the plain paper has a general basis weight (60 g or more), the fixing entrance guide 16 is moved downward (arrows) by the waist of the paper. Direction), the same operation as described above is performed.

  Further, the spring force of the spring 22 used in the present embodiment is also set as in the first embodiment. In other words, the fixing inlet guide 16 is moved to the position of the tangent line G between the fixing nip portion N and the leading end of the conveyance guide 10 with a pressure of about 10 to 60 g, and the discharge separation guide 24 is rotated in the R direction accordingly. Is set to

  Moreover, although the nonwoven fabric (brand name: Nomex felt) which consists of an aramid fiber was used as a water absorption member in a present Example, for example, what is necessary is just a porous felt like a non-woven processed polyimide, and the whole surface has a density. Those having excellent homogeneity are more preferable.

  In this embodiment, as a member for providing the water absorbing felt 21 that is brought into contact with the pressure roller 34, the fixing inlet guide 16 that guides the paper P to the fixing nip portion N and the paper P conveyed from the fixing nip portion N are used. Although the paper discharge separation guide 24 for guiding to the paper discharge unit is used, the present invention is not limited to this, and any member near the fixing nip N may be used.

  In this embodiment, as a means for bringing the water-absorbing felt 21 into contact with the pressure roller 34, the pressure of the paper P against the fixing inlet guide 16 is used. Any device that uses and detects the amount of slack and pressure may be used.

  Further, the link mechanism between the fixing inlet guide 16 and the paper discharge separation guide 24 is not limited to the interlocking method as in this embodiment. For example, a method using a clutch or a spring or the like may be used as long as the member near the downstream side in the conveyance direction of the fixing nip N and the member between the transfer and fixing are interlocked.

Example 3
A third embodiment of the image heating apparatus according to the present invention will be described. The overall configuration of the image heating apparatus of the present embodiment and the image forming apparatus to which the image heating apparatus is applied have the same configuration as the image heating apparatus and the image forming apparatus described in the first embodiment. Therefore, in the apparatus of the present embodiment, members having the same configuration and function are denoted by the same reference numerals, the description of the first embodiment is used, and the description thereof is omitted here.

  In the first and second embodiments, the water absorbing member 21 is brought into contact with the surface of the pressure roller 34 by the force with which the conveyed paper P pushes the fixing inlet guide 16.

  In this embodiment, a loop detecting means for detecting the degree of the loop of the paper P is provided between the transfer and fixing, and the water absorbing member 21 is brought into contact with and separated from the pressure roller 34 based on this detection. The With this configuration, for example, even when thin paper with a basis weight of 60 g or less is passed, the loop detection means accurately and surely determines the paper loop state due to condensation slip, and the water absorbing member at the optimum timing Can be brought into contact with the pressure roller.

  FIG. 13 is a schematic diagram showing a paper path configuration when a loop detection sensor 40 as a loop detection unit is provided between transfer and fixing.

  In this embodiment, a paper discharge sensor 43 is disposed on the paper exit side of the fixing device 11. The paper discharge sensor 43 is for checking that the paper P has passed through the fixing device 11. The paper discharge sensor 43 includes a photo interrupter 44 and an actuator 45, and the photo interrupter 44 is turned on / off according to the displacement of the actuator 45.

  The paper discharge sensor 43 serves to detect that the paper P has reached the position of the paper discharge sensor 43 through the fixing device 11. Further, the paper discharge sensor 43 plays a role in taking a timing for sending the paper P to the double-sided path in the subsequent paper discharge processing part, or the paper P is jammed immediately after fixing. It plays the role of judging by the detection time. Although not shown, the paper discharge sensor 43 is also provided in the apparatuses of the first and second embodiments.

  In this embodiment, the paper discharge sensor 43, as another role, detects that the paper P has surely left the fixing device 11. If the paper P does not reach the paper discharge sensor 43 after the fixing device 11 after a certain period of time after the CPU 27 as the control means of the image forming apparatus main body instructs the start of the printing operation, It is determined that a jam has occurred in the nip portion of the fixing device 11. If the paper P has reached the paper discharge sensor 43, the subsequent interruption of the loop detection sensor 40 is validated, and it is provided for bringing the water absorbent felt 21 into contact with the pressure roller 34 when an upper loop is formed. .

  On the other hand, the loop detection sensor 40 for detecting the loop state of the paper is similarly provided with a photo interrupter 41 and an actuator 42, and the photo interrupter 41 is turned ON / OFF according to the displacement of the actuator 42.

  In the normal paper passing state, while the paper P passes between the paper discharge sensor 43 and the transfer-fixing, the actuator 42 of the loop detection sensor 40 and the actuator 45 of the paper discharge sensor 43 are respectively positioned in the position of FIG. I'm in. At this time, each of the photo interrupters 41 and 44 is ON.

  However, if dew slip occurs in the pressure roller 34 during conveyance, an upper loop that rotates the actuator 42 of the loop detection sensor 40 occurs between the transfer and fixing as shown in FIG. Move to the position shown in FIG. At this time, the photo interrupter 41 is turned off.

  When an upper loop that causes the actuator 42 to rotate is generated, the photo interrupter 41 is shielded from light by the flag. In other words, at this time, the actuator 42 of the loop detection sensor 40 is in the position B in FIG. 5 and the actuator 45 of the paper discharge sensor 43 is in the position A in FIG. A, and the photo interrupter 41 is detected as OFF and the photo interrupter 44 is detected as ON. The Based on this signal, the CPU 27 determines that the sheet is in an upper loop between transfer and fixing.

  Next, the movement of bringing the water absorbing member 21 into contact with the pressure roller 34 using a solenoid that performs ON / OFF control based on a signal from the CPU 27 will be described.

  FIGS. 13 and 14 show the movement when the solenoid 50 and the water absorbent felt 21 are attached only to the fixing inlet guide 16.

  In FIG. 13, as in the first and second embodiments, the position of the fixing inlet guide 16 is fixed by the supporting portion 17 at both ends in the longitudinal direction by a fixing guide (not shown). Further, the lower surface side of the central portion is connected to a solenoid 50 as a switching means via a plunger portion 51 and a link 52. The solenoid 50 is coupled to the CPU 27 which is a control means, and its operation is controlled.

  Normally, in a state where there is no paper, that is, in the apparatus main body OFF state, the solenoid 50 is in the position α (OFF state) in FIG. Further, when the paper discharge sensor 43 and the loop detection sensor 40 are both in the position of FIG. A in the paper passing state, the solenoid 50 is in the OFF state, and accordingly, the fixing inlet guide 16 is also kept at the same position. .

  However, when the CPU 27 determines that the upper loop between the transfer and fixing is as described above, that is, as shown in FIG. 14, the actuator 42 is at the position B in FIG. 14 and the actuator 45 is at the position in FIG. In this case, the solenoid 50 is turned ON and the lower surface side of the fixing inlet guide 16 is pulled in the β direction. As a result, the fixing inlet guide 16 tilts toward the pressure roller 34 with the support shaft 17 as a fulcrum, and the water absorbent felt 21 contacts the surface of the pressure roller 34.

(Modified Example 1)
Next, the movement when the solenoid 53 and the water absorbent felt 21 are attached only to the paper discharge separation guide 24 will be described with reference to FIGS.

  In FIG. 15, the discharge separating guide 24 is fixed at both ends in the longitudinal direction by a support portion 25 by a fixing guide (not shown). Further, the lower surface side of the central portion is connected to a solenoid 53 as a switching means via a plunger portion 54 and a link 55. The solenoid 53 is coupled to the CPU 27 which is a control means, and its operation is controlled.

  In this case as well, the solenoid 53 is in the position α (OFF state) in FIG. Further, when both the paper discharge sensor 43 and the loop detection sensor 40 are in the position of FIG. A in the paper passing state, the solenoid 53 is in the OFF state, and the paper discharge separation guide 24 is kept at the same position accordingly. Yes.

  However, when the CPU 27 determines that the upper loop between the transfer and fixing is as described above, that is, as shown in FIG. 16, the actuator 42 is in the position B in FIG. 16 and the actuator 45 is in the position in FIG. It is in. In this case, the solenoid 53 is turned ON, and the lower surface side of the paper discharge separating guide 24 is pulled in the β direction in FIG. As a result, the paper discharge separating guide 24 is inclined toward the pressure roller 34 with the support shaft 25 as a fulcrum, and the water absorbent felt 21 contacts the surface of the pressure roller 34.

(Modified Example 2)
Next, the movement when the solenoids 50 and 53 and the water-absorbing felt 21 are attached to both the fixing inlet guide 16 and the paper discharge separating guide 24 will be described with reference to FIGS.

  The basic movement in this embodiment is the same as the movement described above. That is, as shown in FIG. 18, when the actuator 42 is in the position B and the actuator 45 is in the position A, the solenoids 50 and 53 are turned on, and the lower surfaces of the fixing inlet guide 16 and the discharge separation guide 24, respectively. The side is pulled in the β direction. As a result, the fixing inlet guide 16 and the paper discharge separation guide 24 are inclined toward the pressure roller 34 with the support shafts 17 and 25 as fulcrums, respectively, and the respective water absorbent felts 21 are in contact with the surface of the pressure roller 34.

  The merit of providing the solenoid and the water absorbing member in both the fixing inlet guide 16 and the paper discharge separating guide 24 is as follows.

  That is, in addition to the effect of suppressing condensation slip, for example, the ON / OFF of the solenoids 50 and 53 is changed according to the amount and time of the upper loop, or the timing is shifted to pressurize the water absorbing member more effectively. It can also be brought into contact with the roller 34.

(Control flow)
FIG. 19 simply shows a control flow of the above operation. In the normal state, the solenoid 50 (or 53) is in an OFF state, and is turned ON as an interrupt control only under the above conditions.

  In the control flow shown in FIG. 19, first, when the CPU 27 instructs the start of the printing operation, the time when the paper passes the top sensor 9 (FIG. 1) is defined as S-1. The time when the paper P reaches the paper discharge sensor 43 after a certain time from the time S-1 is defined as S-2. If the paper discharge sensor 43 is ON at this time (the actuator 45 is in the A position), the next time Go to step. If it is OFF (actuator 45 is in the B position), it is determined that a jam has occurred, and energization control of the apparatus body is stopped. When the paper discharge sensor 43 is ON in S-2, it is confirmed whether the loop detection sensor 40 is ON / OFF in the next step S-3. If the loop detection sensor 40 is ON at the time of S-3 (the actuator 42 is in the A position), the sheet passing is continued with the solenoid 50 (or 53) OFF in the initial state. However, when the loop detection sensor 40 is turned off at the time of S-3 (the actuator 42 is in the B position), it is determined that the conveyed sheet is in an upper loop between transfer and fixing. Based on this determination, the CPU 27 turns on the solenoid 50 (or 53) as interrupt control, and rotates the fixing inlet guide 16 to bring the water absorbent felt 21 into contact with the pressure roller 34.

  On the other hand, the CPU 27 stores the time during which the paper P passes the top sensor 9 in S-1. Thereby, the time for the paper P to pass through the paper discharge sensor 43 is predicted. The time when the paper P is predicted to pass the paper discharge sensor 43 is S-4. In S-4, when the detection of the paper discharge sensor 43 is OFF (the actuator 45 is in the B position), it is determined that the paper P has normally passed through the paper discharge sensor 43, and the printing operation is terminated and the next printing operation is performed. (S-5). If the detection of the paper discharge sensor 43 is ON (actuator 45 is at position A), it is determined that a stay jam has occurred from the fixing to the paper discharge sensor unit, and the energization control of the main body is stopped.

  As described above, the loop detecting means 40 for detecting the degree of the paper loop between the transfer and fixing is provided, and based on this detection, the water absorbing member 21 is controlled to contact and separate from the pressure roller 34. Thus, the following effects can be obtained.

  In other words, for example, even when thin paper with a basis weight of 60 g or less is passed, the loop detection means 40 can accurately and reliably determine condensation slip, and pressurizes the water absorbing member 21 at an optimal timing. The roller 34 can be brought into contact. Accordingly, it is possible to achieve both the extension of the life of the pressure roller 34 and the prevention of dirt, or the suppression of condensation slip and the prevention of jamming associated therewith.

  Further, by rotating the member (sheet discharge separation guide) 24 on the downstream side of the fixing nip using the solenoid 53, a simple structure and a reduction in size can be achieved without the need for a link mechanism as in the second embodiment. Can be planned. Further, by providing solenoids 50 and 53 in the fixing inlet guide 16 and the paper discharge separation guide 24, respectively, for example, the water absorbing member 21 and the pressure roller as much as necessary according to the amount and time of the upper loop. 34 can be brought into contact with each other. Or it becomes possible to change the timing which each contacts. Thereby, it is possible to achieve an image heating apparatus that is further effective for extending the life of the pressure roller 34 and preventing contamination.

  Moreover, although the nonwoven fabric (brand name: Nomex felt) which consists of an aramid fiber was used as the water absorbing member 21 in a present Example, it should just be a porous felt like a non-woven processed polyimide, for example, and the density as a whole surface Those having excellent homogeneity are more preferable.

  In this embodiment, as a member for providing the water absorbing felt 21 that is brought into contact with the pressure roller 34, the fixing inlet guide 16 that guides the paper P to the fixing nip portion N and the paper P conveyed from the fixing nip portion N are used. A paper discharge separating guide 24 for guiding to the paper discharge unit was used. However, the present invention is not limited to this, and any member near the fixing nip N may be used.

  In the first, second, and third embodiments, the tensionless type fixing device including the fixing film 32 and the pressure roller 34 has been described. However, the principle of the present invention is to use a fixing roller instead of the fixing film 32. The present invention can also be applied to a fixing device.

  Further, the image forming apparatus is not limited to the printer described in the first embodiment, and may be a color image forming apparatus, and other various image forming apparatuses provided with a fixing device known to those skilled in the art. It can be.

1 is a schematic configuration diagram illustrating an embodiment of an image forming apparatus according to the present invention. It is a schematic block diagram which shows one Example of the image heating apparatus according to this invention used for an image forming apparatus. FIG. 3 is a schematic diagram illustrating a paper conveyance state between transfer and fixing of the image forming apparatus according to the first embodiment, and shows a case where a water absorbing member is provided only in the fixing inlet guide. FIG. 3 is a schematic diagram illustrating a paper conveyance state between transfer and fixing of the image forming apparatus according to the first embodiment, and shows a case where a water absorbing member is provided only in the fixing inlet guide. FIG. 3 is a schematic diagram illustrating a paper conveyance state between transfer and fixing of the image forming apparatus according to the first embodiment, and shows a case where a water absorbing member is provided only in the fixing inlet guide. FIG. 10 is a schematic diagram illustrating a sheet loop state between transfer and fixing of the image forming apparatus according to the second embodiment, and illustrates a case where a water absorbing member is provided only in the fixing inlet guide. It is the schematic which shows the flow of the vapor | steam of the image forming apparatus according to a 2nd Example. FIG. 10 is a schematic diagram showing a link mechanism between a fixing inlet guide and a paper discharge separation guide according to the second embodiment, and shows a case where a water absorbing member is provided only in the paper discharge separation guide. It is the schematic which shows the operation | movement of the link mechanism according to 2nd Example, and the paper conveyance state between transfer-fixing, and shows the case where a water absorbing member is provided only in the paper discharge separation guide. FIG. 10 is a schematic view showing a link mechanism between a fixing inlet guide and a paper discharge separating guide according to a modification of the second embodiment, and shows a case where a water absorbing member is provided in both the fixing inlet guide and the paper discharging separation guide. FIG. 10 is a schematic diagram showing the operation of the link mechanism and the paper conveyance state between transfer and fixing according to a modification of the second embodiment, and shows a case where a water absorbing member is provided in both the fixing inlet guide and the paper discharge separating guide. . It is the schematic which shows the paper conveyance state between operation | movement of the link mechanism according to the example of a change of a 2nd Example, and transfer-fixing. It is the schematic which shows operation | movement of the loop detection means according to a 3rd Example, and shows the case where a water absorption member is provided only for the fixing entrance guide. It is the schematic which shows the operation | movement of the loop detection means according to a 3rd Example, and the operation | movement of a fixing inlet guide, and shows the case where a water absorption member is provided only in the fixing inlet guide. It is the schematic which shows the operation | movement of the loop detection means according to the example of a change of a 3rd Example, and shows the case where a water absorption member is provided only in the paper discharge separation guide. It is the schematic which shows the operation | movement of the loop detection means according to the example of a change of a 3rd Example, and the operation | movement of a paper discharge separation guide, and shows the case where a water absorbing member is provided only in the paper discharge separation guide. It is the schematic which shows the operation | movement of the loop detection means according to the example of a change of a 3rd Example, and shows the case where a water absorption member is provided in both the fixing entrance guide and the paper discharge separation guide. FIG. 10 is a schematic diagram illustrating the operation of the loop detection unit and the operations of the fixing inlet guide and the paper discharge separation guide according to a modification of the third embodiment, and a water absorbing member is provided in both the fixing inlet guide and the paper discharge separation guide. Show the case. It is a simplified diagram showing an operation flow of solenoid interrupt control by a loop detection sensor according to the third embodiment. It is a schematic sectional drawing which shows the image heating apparatus of a prior art example. It is the longitudinal direction schematic diagram which shows the image heating apparatus of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging roller 3 Exposure apparatus 4 Developing apparatus 5 Transfer roller 6 Cleaning blade 7 Paper feed cassette 8 Conveyance roller 9 Top sensor 10 Conveyance guide 11 Fixing apparatus (image heating apparatus)
13 Conveying roller 14 Paper discharge tray 15 Paper feeding roller 16 Fixing entrance guide 17 Fixing entrance guide support 18 Fixing entrance guide ring receiving portion 19 Hooking member (connecting means)
20 Hook ring 21 Water absorbing felt (water absorbing member)
22 Spring (biasing member)
24 paper discharge separation guide 25 paper discharge separation guide support portion 26 paper discharge separation guide ring receiving portion 27 CPU
30 Fixing Rotating Body 31 Heater Stay 32 Fixing Film 33 Heater (Heat Generation Means)
34 Pressure roller (Pressure rotating body)
35 Pressure roller mandrel 36 Pressure roller elastic body 40 Loop detection sensor (loop detection means)
41 Photo interrupter for loop detection sensor 42 Actuator for loop detection sensor 43 Paper discharge sensor 44 Photo interrupter for paper discharge sensor 45 Actuator for paper discharge sensor 50 Fixing inlet guide solenoid 51 Fixing inlet guide solenoid plunger 52 Fixing inlet guide solenoid Link portion 53 Discharge separation guide solenoid 54 Discharge separation guide solenoid plunger 55 Discharge separation guide solenoid link portion

Claims (15)

A pressure rotator including a fixing rotator provided with a heat generation unit and a pressure rotator that is driven to rotate by being pressed by the fixing rotator, and is formed by the fixing rotator and the pressure rotator; In an image heating apparatus that heats the image by passing a sheet carrying an image in the nip portion,
An image comprising a water absorbing member for absorbing moisture on the surface of the pressurizing rotator, wherein the water absorbing member contacts and separates from the surface of the pressurizing rotator depending on the state of the sheet being conveyed. Heating device.   The image heating apparatus according to claim 1, wherein the water absorbing member is disposed in the vicinity of the pressure nip portion.   3. The image heating apparatus according to claim 1, wherein the water absorbing member is disposed on a downstream side and / or an upstream side of the pressure nip portion in the paper conveyance direction.   The image heating apparatus according to claim 1, further comprising an inlet guide member that guides the sheet conveyed to the pressure nip portion, wherein the water absorbing member is provided in the inlet guide member.   The image heating apparatus according to claim 4, wherein the water absorbing member comes into contact with the surface of the pressure rotating body when the sheet presses the inlet guide member.   A sheet separation guide member that conveys and guides the sheet that has passed through the pressure nip portion while being separated from the pressure rotator, and the water absorbing member is provided in the sheet separation guide member. The image heating apparatus according to claim 1.   The inlet guide member for guiding the sheet conveyed to the pressure nip portion, and the inlet guide member and the sheet separation guide member are connected by a connecting unit. Image heating device.   8. The image heating apparatus according to claim 7, wherein when the paper presses the inlet guide member, the water absorbing member provided in the paper separation guide member comes into contact with the surface of the pressure rotating body. 9.   An inlet guide member that guides the paper conveyed to the pressure nip portion, and a paper separation guide member that conveys and guides the paper that has passed through the pressure nip portion while being separated from the pressure rotator, The image heating apparatus according to claim 1, further comprising: a first water absorbing member provided in the inlet guide member; and a second water absorbing member provided in the paper separation guide member.   The image heating apparatus according to claim 9, wherein the entrance guide member and the sheet separation guide member are coupled by a coupling unit.   11. The image heating apparatus according to claim 10, wherein the first and second water absorbing members abut on the surface of the pressurizing rotating body when the paper presses the inlet guide member.   Loop detecting means for detecting the degree of loop generated in the paper while being conveyed from the image forming portion for forming an image on the paper to the pressure nip portion, and the water absorbing member is provided from the loop detecting means. The image heating apparatus according to claim 1, 2, 3, 4, 6, or 9, wherein the image heating apparatus is brought into contact with or separated from the surface of the pressure rotator according to information.   The image heating according to claim 12, wherein the loop detection unit includes an actuator that is displaced according to a degree of the loop of the paper, and a photo interrupter that generates a detection signal according to the displacement of the actuator. apparatus.   The image heating apparatus according to claim 13, wherein the image heating apparatus is brought into contact with or separated from the surface of the pressure rotating body based on ON / OFF of the photo interrupter. In an image forming apparatus having image forming means for forming an unfixed toner image on a sheet and a fixing device for fixing the unfixed toner image on the sheet,
The image forming apparatus according to claim 1, wherein the fixing device is the image heating device according to claim 1.

Images