JP2004264648A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image recorder provided with a belt fixing device by which fixing without causing paper deformation is attained regardless of a fixing condition by providing a transfer material ejection path forming means having different curvature and switching the transfer material guide means of the transfer material ejection path forming means corresponding to the existence of an auxiliary nip part and the selection of glossiness. <P>SOLUTION: A fixing device is provided with the transfer material ejection path forming means consisting of a plurality of transfer material guide means for a transfer material after pressing and heating, and the glossiness of a fixed image is selected when pressing and heating the transfer material, and either of the plurality of the transfer material guide means is selected by the transfer material ejection path forming means so as to form a transfer material ejection path. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus used for image formation such as a copying machine, a printer, and a facsimile, and more particularly, to an image forming apparatus having a plurality of transfer material guiding units.
[0002]
[Prior art]
Conventionally, as a fixing device used in an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile, a fixing rubber roller having an elastic layer and maintained at a predetermined temperature, and being pressed against a fixing rubber roller, 2. Description of the Related Art A roller fixing device of a heat roller fixing type in which a transfer material having an unfixed toner image formed thereon is heated while being nipped and conveyed by a pressure rubber roller having an elastic layer is often used.
[0003]
However, in this type of roller fixing device, the heat resistance and heat capacity of the fixing rubber roller are large, so that the warm-up time is long, the temperature inside the elastic layer is high, and the life of the fixing rubber roller is short.
[0004]
In addition, many color images have a large solid area, and many of the solid images are other than black. When a hard roller is used in place of the fixing rubber roller described above, unevenness in gloss due to a difference in glossiness occurs according to unevenness of a transfer material (recording paper) or a toner layer, so that there is a problem that image quality is deteriorated. .
[0005]
In order to solve the problems such as the difference in glossiness that causes uneven gloss, the fixing member uses an endless belt member (fixing belt) and supports and stretches the fixing belt with a plurality of roller members. A fixing roller (supporting pressure roller) inside the belt, a pressing roller (external pressing roller) opposed to the supporting pressing roller with the fixing belt interposed, and a heating member (heating member) having a heating element for heating the fixing belt inside And a supporting nip provided upstream of the supporting pressure roller in the rotation direction of the fixing belt, and provided between the supporting pressing roller and an external pressing roller (pressing roller). 2. Description of the Related Art An image forming apparatus including a belt fixing device that fixes a toner image on a recording sheet at a main nip portion is known (see Patent Document 1).
[0006]
Further, even in the face-down sheet discharging configuration, there is known an image forming apparatus including a belt fixing device capable of separating a heating roller and a pressing roller by a simple configuration and operation and easily removing a jammed recording sheet. (See Patent Document 2).
[0007]
Further, there is known an image forming apparatus including a transfer material guiding unit that can transfer a transfer material from a fixing device to a re-conveying unit without increasing the number of components while suppressing a decrease in the durability and throughput of the fixing device (Japanese Patent Application Laid-Open No. H11-163873). Reference 3).
[0008]
Further, a color image forming apparatus which can easily record a high-quality color image on one side or both sides of a transfer material, has no wrinkles of the transfer material, has a simple structure, and is inexpensive is known. (See Patent Document 4).
[0009]
[Patent Document 1]
JP-A-10-307496
[Patent Document 2]
JP-A-10-207272
[Patent Document 3]
JP-A-2002-169403
[Patent Document 4]
JP-A-5-142959
[Problems to be solved by the invention]
However, in an image forming apparatus having the belt fixing device and a plurality of transfer material guiding means, it is effective to bend the transfer material in a direction opposite to the curl immediately after discharging the fixing nip as a curl correcting means for the transfer material. When the glossiness is selected over a wide range depending on the presence or absence of the sheet, the curl amount of the transfer material greatly changes depending on the presence or absence of the area of the auxiliary nip portion.
[0014]
The present invention solves the above-mentioned problem, and provides a transfer material discharge path forming means having a surface with a different curvature, and transfers the transfer material discharge path forming means in accordance with the presence or absence of an auxiliary nip portion and the glossiness selection. Switching the material guide means, providing an image recording apparatus having a belt fixing device capable of fixing with little paper deformation, regardless of the fixing conditions, and the two transfer material guide means having a comb shape, According to the presence or absence of the auxiliary nip area located prior to the fixing position, one of the two transfer material guide means is moved to the paper discharge path side, and the transfer material curl correction guide having the appropriate curvature surface An object of the present invention is to provide an image recording apparatus capable of performing fixing with little paper deformation irrespective of fixing conditions by selecting (transfer material guiding means).
[0015]
[Means for Solving the Problems]
The object of the present invention is achieved by the following configurations.
[0016]
(1) In an image recording apparatus provided with a fixing device for fixing an unfixed toner image on a transfer material by pressurizing and heating, the fixing device includes a plurality of transfer material guiding means for the transfer material after pressurizing and heating. A transfer material discharging path forming means comprising: a transfer material discharging path forming means for selecting a gloss level of a fixed image when the transfer material is pressurized and heated; An image forming apparatus (first invention), wherein a transfer material discharge path is formed by selecting the following.
[0017]
(2) In an image recording apparatus provided with a fixing device for fixing an unfixed toner image on a transfer material by pressurizing and heating, the fixing device includes two transfer material guiding means for the transfer material after pressurizing and heating. Is provided, and in response to the presence or absence of the area of the auxiliary nip portion located prior to the fixing position, the two transfer material guide means can be switched, and when viewed from a line substantially perpendicular to the transfer material. An image forming apparatus (second invention) characterized in that there is no overlapping portion between the two transfer material guiding means.
[0018]
The present invention is intended to provide an image forming apparatus capable of performing fixing with little paper deformation irrespective of fixing conditions by employing the above configuration.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. Note that the description in this column does not limit the technical scope of the claims and the meaning of terms. Also, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning of the terms of the present invention or the technical scope.
[0020]
(1) A fixing device having a transfer material discharge path forming means and an image forming apparatus having two transfer material guiding means according to the present invention will be described below with reference to FIG.
[0021]
In FIG. 1, the image forming apparatus GS includes an image forming apparatus main body GH and an image reading apparatus YS.
[0022]
The image forming apparatus main body GH is referred to as a tandem-type color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a belt-shaped intermediate transfer body 6, a sheet feeding and conveying unit, and a fixing unit to be described later. Device 17.
[0023]
An image reading device YS including an automatic document feeder 201 and a document image scanning exposure device 202 is provided above the image forming apparatus main body GH. The document d placed on the document table of the automatic document feeder 201 is transported by a transport unit, and one or both images of the document are scanned and exposed by the optical system of the document image scanning and exposing device 202, and are sent to the line image sensor CCD. Is read. At this time, the original D conveyed from the original platen is determined by the gloss level detection sensor PKa used as a gloss level selecting means to determine the gloss of the original image, the monochrome / color of the original image, and the double-sided image. Done.
[0024]
The analog signal photoelectrically converted by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, and the like in an image processing section, and then to an image writing section (exposure means) 3Y, 3M, 3C. Send a signal to 3K.
[0025]
The image forming unit 10Y that forms a yellow (Y) color image has a charging unit 2Y, an exposing unit 3Y, a developing unit 4Y, and a cleaning unit 8Y that are arranged around a photosensitive drum 1Y as an image carrier. The image forming unit 10M that forms a magenta (M) color image includes a photosensitive drum 1M as an image carrier, a charging unit 2M, an exposure unit 3M, a developing device 4M, and a cleaning unit 8M. The image forming unit 10C for forming a cyan (C) color image includes a photosensitive drum 1C as an image carrier, a charging unit 2C, an exposure unit 3C, a developing device 4C, and a cleaning unit 8C. The image forming unit 10K that forms a black (K) color image includes a photosensitive drum 1K as an image carrier, a charging unit 2K, an exposure unit 3K, a developing device 4K, and a cleaning unit 8K. The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure device 3C, and the charging unit 2K and the exposure device 3K constitute a latent image forming unit.
[0026]
Reference numerals 4Y, 4M, 4C, and 4K denote developing devices that include a two-component developer composed of a toner having a small particle diameter and a carrier of yellow (Y), magenta (M), cyan (C), and black (K). .
[0027]
The intermediate transfer member 6 is wound around a plurality of rollers and is rotatably supported. The images of the respective colors formed by the image forming units 10Y, 10M, 10C and 10K are sequentially transferred (primary transfer) onto the rotating intermediate transfer body 6 by the transfer units 7Y, 7M, 7C and 7K and are synthesized. A color image is formed. The recording paper P as a transfer material accommodated in the paper feed cassette 20 is fed by a paper feed unit 21, and is conveyed to a transfer unit 7A via paper feed rollers 22A, 22B, 22C, a registration roller 23, and the like. A color image is transferred onto the recording paper P (secondary transfer). The recording paper P on which the color image has been transferred is formed on the fixing device 17, and is formed on the auxiliary nip portion Na (see FIG. 2, not shown in FIG. 1) located before the fixing position, and on the fixing device 17. The recording paper P is sandwiched in the main nip portion Nb (see FIG. 2, not shown in FIG. 1), and a color toner image (or a toner image) on the recording paper P is fixed by applying heat and pressure to perform recording. The paper is fixed on the paper P, passes through the transfer material discharge path forming means 50, is sandwiched by the paper discharge rollers 24 on the paper discharge path side, and is placed on the paper discharge tray 25 outside the machine.
[0028]
At the time of double-sided image formation, a color image (color toner image) is formed on one surface (front surface), and the recording paper P discharged from the fixing device 17 is branched from a sheet discharge path by a branching unit 26, and each paper is fed. After passing through a lower circulating paper path 27A constituting a conveying means, the sheet is turned upside down by a reversing conveying path 27B which is a re-feeding mechanism (ADU mechanism), passes through a re-feeding conveying section 27C, and is fed by a sheet feeding roller. Merge at 22D. The recording paper P that has been reversely conveyed (circulation reversal conveyance) is again conveyed to the secondary transfer roller 7A via the timing roller 23, and a color image (color toner image) is formed on the other surface (back surface) of the recording paper P. Transferred all at once. The recording paper P to which the color image has been transferred is subjected to a fixing process by the fixing device 17, passes through the transfer material discharge path forming means 50, is sandwiched by the discharge rollers 24 on the discharge path side, and is placed on the discharge tray 25 outside the machine. Placed on
[0029]
On the other hand, after the color image is transferred onto the recording paper P by the transfer means 7A, the residual toner is removed by the cleaning means 8A from the intermediate transfer body 6 obtained by separating the recording paper P by curvature.
[0030]
In the description of the image forming apparatus, color image formation has been described, but the case of forming a monochrome image is also included in the present invention.
[0031]
(2) A fixing device including a transfer material discharge path forming unit including a transfer material guide unit having a plurality of surfaces of curvature according to the present invention will be described below with reference to FIG. FIG. 2A is a diagram showing a case where the pressing means is pressed against an external pressing member to form an auxiliary nip portion, and a transfer material guiding means having a curvature is used as a transfer material discharge path forming means. FIG. 2B is a diagram showing a case in which the pressing means is released from the external pressing member and the flat transfer material guiding means is used as the transfer material discharging path forming means without forming an auxiliary nip portion. is there.
[0032]
The fixing device 17 according to the present invention has a configuration shown in FIG. 2A or FIG. 2B, and includes a fixing belt 27 formed of an endless belt member and an inner peripheral surface of the fixing belt 27. A support pressure roller 17a for supporting and stretching the fixing belt 27; and a heating roller for supporting and stretching the fixing belt 27 on the other inner peripheral surface of the fixing belt 27 and having a halogen heater HLa as a heating element inside. The heating roller 17c is in contact with the supporting pressure roller 17a with the fixing belt 27 interposed therebetween. The heating roller 17c has a halogen heater HLa as a heating element inside, and serves as an external pressing member for pressing (pressing) the supporting pressure roller 17a. And an external pressure roller 17b.
[0033]
A fixing nip Nb is formed between the supporting pressure roller 17a and the external pressure roller 17b with the fixing belt 27 interposed therebetween, and the fixing belt is located upstream of the fixing nip Nb (prior to the fixing nip Nb). 27 and an external pressure roller 17b are opposed to each other to form an auxiliary nip Na for winding the fixing belt 27 around the external pressure roller 17b, and heat and pressurize through the auxiliary nip Na and the fixing nip Nb. Thus, the toner image (or color toner image) on the recording paper P is fixedly fixed. Further, an auxiliary pad HP as pressure means is provided inside the fixing belt 27 so as to face the external pressure roller 17b, and a guide frame GBa as a guide member for stretching the fixing belt 27 is provided. .
[0034]
As the fixing belt 27 wound around the supporting heating roller 17c, as a base, a nickel electroformed belt having an inner diameter of about 60 to 150 mm and a thickness of about 20 to 80 μm, or a heat resistant material such as polyimide having a thickness of about 50 to 200 μm is used. A resin resin belt is used as a base, and the outside (outer peripheral surface) of the base is coated with a silicon rubber having a thickness of about 100 to 500 μm, and a PFA (perfluoropolymer) having a thickness of about 30 to 50 μm is formed on the surface as a release layer. (Alkoxy) or PTFE coating or coated with a PFA tube is used.
[0035]
The supporting pressure roller 17a is, for example, a cylindrical metal pipe 171a having a thickness of about 2 to 5 mm using a steel material such as STKM (carbon steel pipe for machine structure), and a thickness of 0 mm on the outer peripheral surface of the metal pipe 171a. As a soft roller having an outer diameter of about 20 to 50 mm, a silicone rubber layer 172 a of about 0.5 to 5 mm is provided, and a PFA (perfluoroalkoxy) tube 173 a having a thickness of about 30 to 70 μm is provided outside the silicon rubber layer 172 a. Be composed.
[0036]
The external pressure roller 17b is, for example, a cylindrical metal pipe 171b having a thickness of about 2 to 5 mm using steel or aluminum such as STKM (carbon steel pipe for machine structure) and an outer peripheral surface of the metal pipe 171b. A silicone rubber layer 172b having a thickness of 1 to 3 mm, and a release layer 173b using a PFA (perfluoroalkoxy) tube having a thickness of about 20 to 50 μm outside the silicone rubber layer 172b; It is configured as a soft roller of about 80 mm.
[0037]
The supporting and heating roller 17c is formed of a cylindrical metal pipe 171c having a thickness of about 1 to 2 mm using, for example, an aluminum material as a base, and PFA (perfluoroalkoxy) having a thickness of about 10 to 30 μm on the outer peripheral surface of the metal pipe 171c. ) It is configured as a roller member having an outer diameter of about 40 to 80 mm formed with the coating 172c.
[0038]
The support pressure roller 17a is rotationally driven by a drive motor (not shown), and the fixing belt 27 is supported and conveyed by the rotation of the support pressure roller 17a to be driven to rotate. The external pressure roller 17b may be driven to rotate, the fixing belt 27 may be transported by the external pressure roller 17b, and the fixing belt 27 may be driven to rotate.
[0039]
Since the rubber layer of the fixing belt is in contact with the toner layer via the rubber layer of the fixing belt or a very thin layer with releasability, the rubber layer deforms and follows the irregularities of the transfer material and toner layer. Then, the fixing belt makes uniform contact with the toner layer, and uniform fixing without gloss unevenness is performed, the toner image has an appropriate gloss, and after the fixing, the transfer material is stably separated from the fixing belt. .
[0040]
As shown in FIG. 2A, an auxiliary nip portion Na formed between the fixing belt 27, the external pressure roller 17b, and the auxiliary pad HP, and between the support pressure roller 17a and the external pressure roller 17b. With the fixing nip portion Nb, the toner image (or color toner image) on the recording paper P, which enters the fixing area through the entrance guide plate 17s, is heated under pressure and fixedly fixed on the recording paper P.
[0041]
Further, a temperature sensor TSa is provided in contact with or not in contact with the support heating roller 17c to control the temperature of the support heating roller 17c. Further, the fixing belt 27 may be provided with a temperature sensor for detecting a contact or non-contact temperature, and the temperature of the fixing belt 27 may be controlled. Of course, the temperature sensor T can be provided not only on one side but also on both sides.
[0042]
As shown in the fixing device 17 using the fixing belt 27 in FIG. 2A, the fixing belt 27 is pressurized from the inner peripheral surface (inside) of the fixing belt 27 at the entrance of the auxiliary nip Na. An auxiliary pad HP is provided as a pressing means that slides on the fixing belt 27, and the auxiliary pad HP is pressed against the external pressing roller 17b to form an auxiliary nip Na. The auxiliary pad HP is provided in parallel with the center of the external pressure roller 17b, for example, a rectangular silicone rubber foam (150 to 250% foam) having a width of about 8 to 15 mm, solid rubber, heat-resistant resin, or the like. It is made of alumina fiber. Also, for example, the auxiliary motor is provided between the spring receiver SPA and the holding member HG on the auxiliary pad HP side by rotation of an eccentric cam (not illustrated) rotated about an eccentric shaft by a drive motor (not illustrated). The pressure switching means 200 for changing the pressing force of the pressing spring SPa for pressing the pad HP, and changing the load on the external pressure roller 17b at the auxiliary nip Na of the auxiliary pad HP is provided. The auxiliary pad HP is pressed against the external pressure roller 17b to form the auxiliary nip Na as described above. Further, as shown in FIG. 2 (B), the pressure switching means 200 is set in the direction shown by the thick line arrow in the figure, the auxiliary pad HP is set to a state where the pressing is released from the external pressure roller 17b, and the auxiliary nip portion Na is not formed. To The spring receiver SPA is provided with a pressure sensor PSa for detecting a pressure on the recording paper P by the pressure switching means 200.
[0043]
In the fixing device 17, glossiness such as high glossiness or low glossiness is selected by an operation unit (not shown) of the image forming apparatus GS described in FIG. 1 or an external printer.
[0044]
According to the present invention, in the fixing device 17 described with reference to FIG. 2A or FIG. 2B, as described at the beginning, the transfer material is curled immediately after discharging the fixing nip as a curl correcting means for the transfer material. It is effective to bend in the opposite direction, but if you try to select a wide range of glossiness with or without the auxiliary nip, the curl amount of the transfer material greatly changes depending on the presence or absence of the auxiliary nip area. The guide (transfer material guiding means) could not cope.
[0045]
For this reason, the present invention provides a plurality of transfer material guiding means having surfaces with different curvatures, and performs switching in accordance with the presence or absence of an auxiliary nip positioned prior to the fixing position. As will be described later, the plurality of transfer material guides have a comb shape, and one of the transfer material guides is moved toward the paper discharge path (transfer material discharge path), thereby obtaining a curl correction guide (transfer) having an appropriate curvature. Material guide means).
[0046]
For example, as shown in FIG. 2A and FIG. 2B, a transfer material discharge path forming means (including a transfer material discharge path) including two transfer material guide means of a guide plate 50A and a guide plate 50B. Means) 50 is provided, and when it is desired to obtain a high glossiness, the auxiliary pad HP, which is a pressing means, is pressed to form the auxiliary nip portion Na and transfer the guide plate 50A having a large curl correction amount and a curvature. It is used as a material guiding means, and further increases the control temperature of the fixing belt 27. When the glossiness is low, the auxiliary pad HP and the external pressure roller 17b are moved so that the auxiliary nip Na is not formed, and the flat guide plate 50A having a small curl correction amount is used as the transfer material guiding means. The control temperature of the fixing belt 27 is reduced. Intermediate gloss can also be obtained by appropriately combining the temperature level and the presence or absence of the auxiliary nip Na. At this time, the guide plate 50A or the guide plate 50B can be appropriately combined and used.
[0047]
When an image is output in a state where the high gloss image is selected and the auxiliary nip portion Na is provided, the curled recording paper P is bent in reverse by the guide plate 50A having the curvature shown in FIG. To correct that curl. When the image is output in a state where the low gloss image is selected and there is no auxiliary nip portion Na, the curl amount is small, and the flat guide plate 50B having a small correction effect shown in FIG. Move to the paper ejection path side.
[0048]
According to the present invention, as described above, the transfer material discharge path forming means (means for transferring the transfer material discharge path) having the transfer material guide means having surfaces of different curvatures is provided, and the presence or absence of the auxiliary nip portion and the glossiness selection are selected. In response to the above, by using an image recording apparatus having a belt fixing device for switching the transfer material guiding means of the transfer material discharge path forming means, a heating temperature for heating the transfer material and a transfer of the transfer material are adopted. It is possible to provide an image forming apparatus capable of fixing with little deformation of the transfer material irrespective of fixing conditions such as a conveying speed and a pressure for pressing the transfer material.
[0049]
(3) Two transfer material guiding means according to the present invention will be described below with reference to FIG.
[0050]
As the two transfer material guide means (transfer material curl correction guide having a surface with an appropriate curvature) according to the present invention, for example, a guide plate 50A having a curvature described with reference to the fixing device 17 of FIG. And the guide plate 50B. The curvature (R) of the guide plate 50A is appropriately selected depending on the linear velocity, the roller diameter of the external pressure roller 17b, the width of the auxiliary nip Na, the temperature of the fixing belt 27, and the like. R50 mm was good.
[0051]
According to the present invention, the fixing device is provided with two transfer material guiding means (a guide for correcting the curl of the transfer material having an appropriate curvature) with respect to the transfer material after the pressure and the heating, and the position is set before the fixing position. In response to the presence or absence of the region of the auxiliary nip portion, the two transfer material guides are switchable, and when viewed from a line substantially perpendicular to the transfer material, the two transfer material guides overlap each other. It has no part.
[0052]
For example, as shown in FIG. 3, the guide plate 50A and the guide plate 50B have a comb shape when viewed from a direction substantially perpendicular to the surface in the transfer material advancing direction. , Can exchange positions with each other with minimal space.
[0053]
In addition to the presence or absence of an auxiliary nip portion Na (see FIG. 2 and not shown in FIG. 3) positioned prior to the fixing position, changing the linear velocity or changing the temperature allows the transfer material to be used again. Even when the curl amount of the transfer material changes depending on the type, it is effective to select a guide plate 50A having a curvature or a planar guide plate 50B similarly according to the curl amount.
[0054]
As described above, since the rubber layer of the fixing belt comes into contact with the toner layer via the rubber layer of the fixing belt or a very thin layer having releasability, the rubber layer is deformed and the transfer material and the toner are removed. Following the unevenness of the layer, the fixing belt makes uniform contact with the toner layer, uniform fixing without gloss unevenness, etc., the toner image has moderate gloss, and after fixing, the transfer material is stable Separate from the fixing belt. Further, as described with reference to FIG. 2, the deformation of the transfer material (curl of the transfer material) caused by the auxiliary nip portion causes the guide plate 50A having a curvature to move to the paper discharge path (transfer material discharge path). , And is discharged to a discharge tray 25 (see FIG. 1, not shown in FIG. 3).
[0055]
In the present embodiment, when a low glossiness is obtained, a pressing unit (auxiliary pad) or the like moves to perform a fixing operation without forming an auxiliary nip positioned prior to a fixing position. In this case, the transfer material is slightly deformed, and instead of the guide plate 50A having the curvature, the planar guide plate 50B moves to the paper discharge path (transfer material discharge path) side to deform the transfer material. Instead, the paper is discharged to a paper discharge tray 25 (see FIG. 1, not shown in FIG. 3) or the like.
[0056]
In the above-described embodiment, the case where the glossiness is selected by combining the width of the auxiliary nip portion located before the fixing position and the temperature of the fixing belt in the fixing device using the fixing belt has been described. The roller fixing device is similarly effective when the deformation amount (curl amount) of the transfer material changes depending on the selection of the fixing conditions and the type of the transfer material.
[0057]
According to the present invention, as described above, the two transfer material guiding means (transfer material curl correction guide having a surface with an appropriate curvature) are in a comb shape, and the presence or absence of the area of the auxiliary nip portion located before the fixing position is determined. Correspondingly, an image recording apparatus having a configuration in which one of the two transfer material guide means is moved to the paper discharge path side and a transfer material curl correction guide (transfer material guide means) having an appropriate curvature is selected. Accordingly, it is possible to provide an image forming apparatus capable of performing fixing with little deformation of the transfer material regardless of fixing conditions.
[0058]
As described above, by adopting the configuration as in the present invention, it is possible to obtain an image forming apparatus capable of fixing with little paper deformation regardless of fixing conditions.
[0059]
【The invention's effect】
According to the present invention, there is provided a transfer material discharge path forming means having transfer material guide means having surfaces of different curvatures, and the transfer material discharge means is provided in accordance with the presence or absence of an auxiliary nip portion and the selection of glossiness. By taking an image recording apparatus having a belt fixing device for switching the transfer material guiding means of the path forming means, a heating temperature for heating the transfer material, a conveyance speed for conveying the transfer material, and a pressurization for pressing the transfer material It is possible to provide an image forming apparatus capable of performing fixing with little deformation of a transfer material regardless of fixing conditions such as pressure.
[0060]
According to the fifth or sixth aspect, the two transfer material guide means (the transfer material curl correction guide having an appropriate curvature) have a comb shape, and the presence or absence of the area of the auxiliary nip portion located before the fixing position. In response to the above, one of the two transfer material guide means is moved to the paper discharge path side, and the transfer material curl correction guide (transfer material guide means) having a surface with an appropriate curvature is selected. Accordingly, it is possible to provide an image forming apparatus capable of performing fixing with little deformation of the transfer material regardless of fixing conditions.
[Brief description of the drawings]
FIG. 1 is a schematic sectional configuration diagram of a fixing device having a transfer material discharge path forming means according to the present invention and an image forming apparatus having two transfer material guiding means.
FIG. 2 is a schematic cross-sectional view of a fixing device including a transfer material discharging path forming unit including a transfer material guiding unit having a plurality of surfaces of curvature according to the present invention.
FIG. 3 is a diagram showing two transfer material guiding means according to the present invention.
[Explanation of symbols]
1Y, 1M, 1C, 1K Photoreceptor drums 2Y, 2M, 2C, 2K Charging means 3Y, 3M, 3C, 3K Exposure means 4Y, 4M, 4C, 4K Developing device 17 Fixing device 17a Support pressure roller 17b External pressure roller 17c Supporting heating roller 26 Branching means 27A Circulating paper path 27B Reverse transport path 27C Re-feed transport section 27 Fixing belt 50 Transfer material discharge path forming means 50A, 50B Guide plate 200 Pressure switching means HLa Halogen lamp HP Auxiliary pad GS Image Forming device Na Auxiliary nip Nb Main nip PSa Pressure sensor TSa Temperature sensor P Recording paper

Claims (6)

An image recording apparatus including a fixing device that fixes an unfixed toner image on a transfer material by applying pressure and heat,
The fixing device is provided with a transfer material discharge path forming means including a plurality of transfer material guiding means for the transfer material after heating under pressure.
When the transfer material is pressurized and heated, the glossiness of the fixed image can be selected, and the transfer material discharge path is formed by selecting one of the plurality of transfer material guide means by the transfer material discharge path forming means. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the plurality of transfer material guides have surfaces having different curvatures in a transfer material discharge direction. The fixing device has a fixing belt that contacts an unfixed toner image during a fixing operation, and a pressing unit that contacts the fixing belt via a transfer material, and the fixing belt contacts the pressing unit. The image forming apparatus according to claim 1, further comprising a pressure switching unit that switches an area of the auxiliary nip portion. The fixing device changes any one, or any two, or three fixing conditions of a heating temperature for heating the transfer material, a conveyance speed for conveying the transfer material, and a pressurizing pressure for pressing the transfer material. The image forming apparatus according to claim 1, further comprising a fixing condition changing unit. An image recording apparatus including a fixing device that fixes an unfixed toner image on a transfer material by applying pressure and heat,
The fixing device is provided with two transfer material guide means for the transfer material after pressurized and heated,
According to the presence or absence of the area of the auxiliary nip portion located prior to the fixing position, the two transfer material guide means can be switched, and when viewed from a line substantially perpendicular to the transfer material, the two transfer material guides can be switched. An image forming apparatus, wherein the image forming apparatus does not have a portion overlapping each other between the units. The image forming apparatus according to claim 5, wherein the two transfer material guides have a substantially comb shape in a traveling direction of the transfer material.

Images