JP2014035355A - Holding and conveying apparatus and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the amount of water contained in a recording medium before fixation in a fixing device, thereby preventing blister during fixation and forming a high-quality image.SOLUTION: A holding and conveying apparatus includes: an upper roller 102A; a lower roller 102B arranged in a position opposite the upper roller 102A and conveying a sheet P held with the upper roller 102A; a heater 105 for heating any of the upper and lower rollers 102A, 102B; water content detection sensor 211 disposed on the upstream of a conveyance path of the sheet P, with respect to the upper and lower rollers 102A, 102B, for detecting the amount of water contained in the sheet P; and upper sheet guides 103A, 103B for guiding the sheet P to the upper and lower rollers 102A, 102B. On the basis of the amount of water contained in the sheet P detected by the water content detection sensor 211, angles of the upper sheet guides 103A, 103B with respect to the upper and lower rollers 102A, 102B are controlled.

Description

  The present invention relates to a nipping and conveying apparatus and an image forming apparatus. More specifically, the present invention relates to a nipping and conveying apparatus that is mounted on an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, or a printer.

  Conventionally, various image forming apparatuses using an electrophotographic system have been devised as image forming apparatuses such as copying machines, facsimiles, and printers, and are well known in the art. In the image forming process, an electrostatic latent image is formed on the surface of the photosensitive drum as an image carrier, and the electrostatic latent image on the photosensitive drum is developed with a toner as a developer to be visualized and developed. The image is formed by a process in which the transferred image is transferred to recording paper (also referred to as paper, recording medium, or recording material) by a transfer device to carry the image, and the toner image on the recording paper is fixed by a fixing device using pressure, heat, or the like. Yes.

  In recent years, copying machines and printers have become more colorized, faster, and higher in image quality, especially in the field of on-demand publications, etc., because they are relatively easy and can handle small numbers of copies. The trend of producing publications that have been created by the printing method so far with color copiers and color printers has become remarkable.

  In addition, in order to improve image quality, there are an increasing number of cases where high white glossy paper that has been used in the printing method has been used as printer paper. However, coated paper having such high white gloss is used in electrophotography. When used in a copying machine or printer of the type, blisters are likely to occur when fixing a toner image.

  Blisters are those in which the water inside the paper is heated to become water vapor when the toner image is heated and fixed, the water pressure inside the paper rises, and when this water vapor is discharged out of the paper, it causes swelling. Yes (hereinafter referred to as paper blister).

  When the generated high-pressure water vapor is discharged to the outside of the paper through the gap inside the coating layer to this paper blister, if there is a toner image on the water vapor discharge path, it will break through the toner image portion and flow out. In other words, fine blisters and through-holes are generated in the coated paper and the quality is lowered (hereinafter referred to as toner blister). This toner blister can be a serious defect in the image. Hereinafter, the term “blister” refers to both paper blisters and toner blisters.

  In order to solve such a problem, for example, in Patent Document 1, as shown in FIG. 4, an endless belt-like film member 94 that rotates with a recording paper P stretched around a plurality of support rollers 91 to 93 is used. A recording paper dehumidifying device 90 is disclosed in which the moisture content is reduced by bringing the outer peripheral surface into contact with heating. The recording paper dehumidifying device 90 includes a heating means 95 that heats the film member 94 to a predetermined temperature before contacting the recording paper P.

  However, as in Patent Document 1, in the method of directly heating the film member that transports the recording paper and suppressing the occurrence of paper blisters, the heat resistance of the film member is required, and when the image forming apparatus is made faster, Since heating to a higher temperature is required, there is a problem that it is difficult to cope with a higher speed.

  In addition, toner blisters have different generation levels and frequency depending on the moisture content of the recording paper. Therefore, heating the toner blisters to a high temperature will cause other problems such as hindering transferability. was there.

  Accordingly, the present invention provides a nipping and conveying apparatus capable of eliminating the generation of blisters at the time of fixing and obtaining a high-quality image by effectively reducing the moisture content of the recording medium before fixing by the fixing apparatus, and the nipping and conveying apparatus. An object of the present invention is to provide an image forming apparatus provided with a conveying device.

  In order to achieve such an object, a sandwiching and conveying apparatus according to the present invention is provided at a position facing a first roller and the first roller, and sandwiches and conveys a recording medium between the first roller and the first roller. A second roller, heating means for heating either the first roller or the second roller, and an upstream side of the recording medium conveyance path with respect to the first roller and the second roller; The moisture content detecting means for detecting the moisture content of the recording medium; and a paper guide plate for guiding the recording medium to the first roller and the second roller, and the recording by the moisture content detecting means. Based on the detection result of the moisture content of the medium, the angle of the paper guide plate with respect to the first roller and the second roller is controlled.

  According to the present invention, it is possible to reduce the moisture content of the recording medium before fixing by the fixing device, eliminate the generation of blisters during fixing, and obtain a high-quality image.

1 is a cross-sectional view illustrating an embodiment of an image forming apparatus according to the present invention. It is sectional drawing which shows one Embodiment of the clamping conveyance apparatus which concerns on this invention. (A) is a schematic diagram of the upper side, lower roller and upstream side paper guide when the upstream side paper guide is in the initial position, and (B) and (C) are the leading ends of the upstream side paper guide approaching the upper roller side. FIG. 6 is a schematic diagram of the upper and lower rollers and the upstream paper guide when the angle with respect to the main body is controlled to be changed as described above. It is sectional drawing which shows the structure of the conventional dehumidification apparatus of a recording paper.

  Hereinafter, a configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

[First Embodiment]
(Image forming device)
FIG. 1 is a schematic configuration diagram illustrating the overall configuration of a tandem type color copier that is an embodiment of an image forming apparatus according to the present invention. The outline and operation of the internal configuration of the image forming apparatus will be described with reference to FIG.

  The image forming apparatus 200 includes an image forming unit 200A positioned at the center of the apparatus main body, a paper feeding unit 200B positioned below the image forming unit 200A, and an image reading unit (not shown) positioned above the image forming unit 200A. doing.

  An intermediate transfer belt 213 having a transfer surface extending in the horizontal direction is disposed in the image forming unit 200A, and an image having a color complementary to the color separation color is formed on the upper surface of the intermediate transfer fixing belt 213. Is provided.

  That is, photoconductors 205Y, 205M, 205C, and 205K as image carriers capable of carrying an image of toners of complementary colors (yellow, magenta, cyan, and black) are juxtaposed along the transfer surface of the intermediate transfer belt 213. Has been.

  Each of the photoconductors 205Y, 205M, 205C, and 205K is configured by a drum that can rotate in the same direction (counterclockwise direction), and around the optical writing device 201 that performs image forming processing in the rotation process, Charging devices 202Y, 202M, 202C and 202K, developing devices 203Y, 203M, 203C and 203K, primary transfer devices 204Y, 204M, 204C and 204K and a cleaning device (not shown) are arranged.

  Each developing device 203Y, 203M, 203C, 203K contains a respective color toner. The intermediate transfer belt 213 is configured to be able to move in the same direction at the position facing the photoconductors 205Y, 205M, 205C, and 205K by being wound around a driving roller and a driven roller. In addition, a secondary transfer roller 215 is provided at a position facing a roller 214 that is one of the driven rollers.

  On the other hand, the paper P as a recording medium stacked in the paper feed tray 220 is taken out by the pick roller 221, and the transport roller 222 moves the transport path R 1 in the direction toward the registration roller 223 and the secondary transfer roller 215. Be transported.

  Further, the moisture content detection sensor 211 installed in the middle of the conveyance path R1 detects the moisture content of the sheet P, and based on the detected value, the angle of the upstream sheet guides 103A and 103B of the nipping and conveying apparatus 100 with respect to the roller 102 is determined. In a controlled state (FIG. 2, details will be described later), the sheet is conveyed to the fixing device 206.

  In image formation in the image forming unit 200A, the surface of the photoreceptor 205Y is uniformly charged by the charging device 202Y, and an electrostatic latent image is formed on the photoreceptor 205Y based on image information from the image reading unit. The electrostatic latent image is visualized as a toner image by a developing device 203Y containing yellow toner, and the toner image is primarily transferred onto a transfer belt 213 by a primary transfer device 204Y to which a predetermined bias is applied. Is done. The other photoconductors 205M, 205C, and 205K also form similar images only with different toner colors, and the toner images of the respective colors are sequentially transferred onto the intermediate transfer belt 213 by the electrostatic force and superimposed.

  Next, the toner image primarily transferred from the photoconductors 205Y, 205M, 205C, and 205K onto the intermediate transfer belt 213 is transferred onto the paper P conveyed by the roller 214 and the transfer roller 215. The sheet P onto which the toner image has been transferred is further conveyed to the fixing device 206 and is fixed at a fixing nip N between the fixing belt 209 and the pressure roller 210.

  The fixing device 206 has a fixing member (fixing belt 209) that is stretched between the fixing roller 207 and the heating roller 208 with a certain tension, and presses the fixing member (fixing belt 209) so as to be freely rotatable on the lower side. And a pressure member (pressure roller 210) for forming the nip portion N. Here, the fixing belt 209 is an endless belt, and has a two-layered structure in which an elastic layer such as a silicon rubber layer is formed on a base material such as nickel, stainless steel, or polyimide. The heating roller 208 is an aluminum or iron hollow roller and has a heat source including a heater 208h such as a halogen heater inside. Next, the paper P discharged from the fixing nip portion is sent out to the stacker 216 along the discharge path.

  When double-sided printing is executed in the image forming apparatus 200, the paper transport unit 217 transports the paper P transported along the transport path R1 this time along the reverse transport path R2, and reverses the front and back of the paper P. Then, it is transported again along the transport path R1. Similarly, during double-sided printing, the moisture content detection sensor 211 disposed in the transport path R1 detects the moisture content of the paper P, and based on the detected value, the upstream side paper guides 103A and 103B of the nipping / conveying device 100 with respect to the rollers 102 The angle is controlled.

  In the example of FIG. 1, the installation position of the moisture content detection sensor 211 is arranged immediately before (on the upstream side) the nipping and conveying apparatus 100, but is most preferably arranged immediately before or after the conveying roller 222. This is because the temperature rise / cooling time of the first roller 102A to be controlled can be secured, and the paper P can be transported without reducing the productivity.

  As the moisture detection sensor 211, a known or new sensor may be used, and is not particularly limited. For example, a microheater type moisture detection sensor can be used (reference: Japanese Patent Laid-open No. Hei. 7-55748).

(Nipping conveying device)
Next, the configuration and operation of the nipping and conveying apparatus 100 included in the image forming apparatus 200 will be described. FIG. 2 is a cross-sectional view showing an embodiment of the nipping and conveying apparatus 100.

  The nipping and conveying apparatus (nipping and conveying apparatus 100) according to the present embodiment is provided at a position facing the first roller (upper roller 102A) and the first roller, and between the first roller and the recording medium ( A second roller (lower roller 102B) for nipping and conveying the sheet P), a heating means (heater 105) for heating either the first roller or the second roller, and the first roller and the second roller. On the other hand, a moisture content detection means (moisture content detection sensor 211) that is provided on the upstream side of the conveyance path of the recording medium and detects the moisture content of the recording medium, and guides the recording medium to the first roller and the second roller. A sheet guide plate (upstream sheet guides 103A and 103B), and the angle of the sheet guide plate with respect to the first roller and the second roller based on the detection result of the moisture content of the recording medium by the moisture detection unit It is intended to control. In addition, the code | symbol in embodiment and the example of application are shown in a parenthesis.

  The nipping / conveying apparatus 100 is disposed on the upstream side of the registration roller 223 in the image forming apparatus 200. The nipping and conveying apparatus 100 includes a pair of rollers 102A (hereinafter referred to as upper rollers) and 102B (hereinafter referred to as lower rollers), upstream paper guides 103A and 103B for guiding paper P, and downstream paper guides 104A and 104B. And a frame 101 that supports the upper roller 102A. Here, the upstream side paper guides 103A and 103B are supported such that their angles can be varied (details will be described later).

  The upper roller 102A includes a heater 105 (heating means) and a temperature sensor 106 that detects the temperature of the upper roller 102A.

  The nipping and conveying apparatus 100 first guides the supplied paper P between the upstream paper guides 103A and 103B and passes between the auxiliary paper conveyance rollers 107A and 107B, and then the upper roller 102A and the lower roller. After passing between 102B, it guides between the downstream paper guides 104A and 104B, and the paper P is discharged.

  The upper roller 102A and the lower roller 102B are provided opposite to each other at positions where the paper P is sandwiched in the vertical direction, and function as a first roller and a second roller whose circumferential surfaces move around. The upper roller 102A disposed on the upper side is a drive roller, and is driven to rotate by a drive motor (not shown). The lower roller 102B disposed on the lower side is a driven roller, and conveys the paper P by contacting the rotating upper roller 102A.

  The pair of auxiliary transport rollers 107A and 107B are members that transport the paper P with the paper P interposed therebetween, and the paper P can be transported by the auxiliary transport rollers 107A and 107B even when the rollers 102A and 102B are separated. Of the pair of auxiliary conveying rollers 107, the upper auxiliary conveying roller 107A is a driving roller, and the lower auxiliary conveying roller 107B is a driven roller.

  Upper auxiliary conveyance roller 107A is driven via a gear (not shown) coupled to upper roller 102A. The lower roller 102B is given a load toward the upper roller 102A, and the paper P is conveyed while being sandwiched between the upper roller 102A and the lower roller 102B. The upper roller 102A is supported by a bearing (not shown), and the bearing is fixed to the frame 101. The lower roller 102B is supported by a bearing 108, and the bearing 108 is supported by the outer arm 109 from below.

  The bearing 108 is restrained from moving in the lateral direction by the U-shaped groove of the lower frame 115 and can move in the vertical direction. The outer arm 109 and the inner arm 110 can rotate around the arm fulcrum 111.

  A bearing 112 is fixed to the inner arm 110, and the bearing 112 is in contact with the cam 113. Further, a spring member 114 is provided between the outer arm 109 and the inner arm 110, and when the cam 113 rotates, the inner arm 110 rotates in the C direction around the fulcrum 111, so that a load is applied to the spring member 114. The repulsive force causes the outer arm 109 to rotate in the C direction around the fulcrum 111, the lower roller 102B is lifted by the outer arm 109, and the upper roller 102A and the lower roller 102B are in pressure contact.

  In a state where the upper roller 102A and the lower roller 102B are in pressure contact, the paper P passes through the pressure contact portion, so that moisture inside the paper can be reduced.

  In this embodiment, the example in which the upper roller 102A includes the heating unit has been described. However, the lower roller 102B may include the heating unit. As the heating means, for example, a halogen heater can be used. Further, the heating means may heat the roller from the outside of the roller.

  Further, an example in which the upper roller 102A is a driving roller and the lower roller 102B is a driven roller has been described. However, the lower roller 102B may be a driving roller, and the upper roller 102A may be a driven roller. Means may be provided. Further, although the example in which the lower roller 102B is provided with means for pressing / separating with respect to the upper roller 102A has been described, a means for pressing / separating with respect to the lower roller 102B may be provided on the upper roller 102A.

(Paper guide plate control by moisture detection sensor)
Next, control of the nipping and conveying apparatus 100 based on the detection of the moisture-containing detection sensor 211 will be described. The nipping and conveying apparatus 100 according to the present embodiment is based on the moisture content of the sheet P detected by the moisture detection sensor 211 (detected value of the sensor), and the rollers 102 of the upstream side paper guides 103A and 103B of the nipping and conveying apparatus 100. The angle with respect to is controlled.

  With reference to FIGS. 3A to 3C, an example of the angle control of the upstream side paper guides 103A and 103B of the nipping and conveying apparatus 100 will be described.

Here, FIG. 3A shows a schematic diagram of the rollers 102A and 102B and the upstream paper guide 103 when the upstream paper guides 103A and 103B are in the initial positions. FIG. 3B and FIG. Is the roller 102A when the angle with respect to the main body portions 103A ₂ and 103B ₂ is controlled so that the leading ends 103A ₁ and 103B ₁ of the upstream side paper guides 103A and 103B approach the upper roller 102A side heated by the heater 105. , 102B and the upstream side paper guide 103 are shown. Hereinafter, the respective states of FIGS. 3A, 3B, and 3C are also referred to as setting positions A, B, and C.

The upstream side paper guides 103A and 103B are configured such that at least the leading end portions 103A ₁ and 103B _{1 of the} guides can change the angle with respect to the main body portions 103A ₂ and 103B _{2 as} shown in FIGS. It has become. For example, the distal end portions 103A ₁ and 103B ₁ and the main body portions 103A ₂ and 103B ₂ are formed of separate pieces of the same material, and the distal end portions 103A ₁ and 103B ₁ are displaced according to the rotation of a cam (not shown). Thus, the angle with respect to the main body portions 103A ₂ and 103B ₂ is varied.

Here, when the moisture content of the paper P detected by the moisture detection sensor 211 is large, the heater 105 is provided from the initial position shown in FIG. 3A, as shown in FIGS. The tip portions 103A ₁ and 103B ₁ are displaced so as to approach the upper roller 102A side.

That is, when the angles of the leading end portions 103A ₁ and 103B ₁ are controlled as shown in FIGS. 3B and 3C, the paper P follows the upper roller 102A as shown by the dotted line (paper behavior) in the figure. Therefore, the sheet P can receive more heat from the upper roller 102A even at a portion other than the nip portion of the roller 102, thereby allowing more moisture to escape. Further, at the angle shown in FIG. 3C, the paper P is heated by the stiffness (weak pressure) of the paper P before entering the nip portion of the roller 102, so that a paper blister that breaks the inside of the paper is generated. It becomes possible to reduce moisture efficiently without causing any problems.

  According to the nipping and conveying apparatus 100 described above, by controlling the angles of the upstream side paper guides 103A and 103B based on the moisture content of the paper P detected by the moisture detection sensor 211, a paper having a high moisture content, for example, Even when printing a sheet with high air permeability such as a coated paper for printing, it is possible to release more water in the nipping and conveying apparatus 100. Therefore, it becomes possible to reduce the amount of moisture before reaching the fixing nip N, optimize the state of paper (water content) before fixing, eliminate the generation of blisters at the time of fixing, and obtain a high-quality image. Can be obtained.

[Second Embodiment]
Hereinafter, other embodiments of the nipping and conveying apparatus according to the present invention will be described. In addition, description about the same point as the said embodiment is abbreviate | omitted suitably.

  As shown in FIG. 1, the moisture content detection sensor 211 may be provided so that the moisture content can be detected on the side of the paper P on which the toner image is formed (no toner image is formed at the time of detection). preferable.

  In particular, when performing double-sided printing, if the moisture content detection sensor 211 is installed on the toner surface side, the moisture content detection value of the paper P may be lowered by the toner. For this reason, it is preferable to install the moisture detection sensor 211 on the side on which the toner surface is not printed, because the moisture amount can be detected with high accuracy while maintaining higher sensor sensitivity.

  By setting the moisture content detection sensor 211 to the installation position shown in FIG. 1, the moisture content can be detected on the image forming surface side in both single-sided printing and double-sided printing. Detection on the formed toner surface side can be avoided.

[Third Embodiment]
Further, the angle of the upstream side paper guides 103A and 103B of the nipping / conveying device 100 with respect to the roller 102 is controlled based on the type of the paper (paper type) together with the moisture content of the paper P detected by the moisture content detection sensor 211. It is also preferable to do.

  For example, as described above, the toner blister has a worse blister level as the moisture content of the paper increases. In addition, the coated paper having a coating layer tends to have a blister level that is poorer than that of uncoated paper. The blister level of the coated paper is poor because there is less moisture escape space than uncoated paper.

  On the other hand, in the case of uncoated paper, since the back side where printing is not performed is also uncoated paper, water vapor generated inside the paper can escape not only from the toner image portion but also from the back side of the paper where there is no toner. Compared with, blister levels tend to be good.

  Therefore, in this embodiment, the angle of the upstream paper guides 103A and 103B with respect to the roller 102 is controlled using the moisture content of the paper and the matrix of the paper type as shown in Table 1, for example, the coated paper is coated more than the uncoated paper. By increasing the angle of the paper guide plate with paper, the heating time for the paper P is secured, and water vapor inside the paper is efficiently released. Thereby, the state (water content) of the sheet before fixing can be further optimized. In Tables 1 to 3, A, B, and C indicate the set positions A, B, and C (FIG. 3).

[Fourth Embodiment]
In addition, the angle of the upstream side paper guides 103A and 103B of the nipping and conveying apparatus 100 with respect to the roller 102 is controlled based on the air permeability of the paper in accordance with the moisture content of the paper P detected by the moisture content detection sensor 211. Is also preferable.

  Generally, even in coated paper, the ease of water vapor escape varies depending on the coating material. Therefore, it is also preferable to detect the air permeability which is also a parameter indicating the ease of water vapor escape. As the air permeability measurement means, for example, a Gurley air permeability meter standardized by JIS or the like can be used. The air permeability (sec) is a value obtained by measuring the time for a gas having a certain volume to pass, and means that the longer the time, the more difficult the gas escapes, that is, the blister level becomes worse. .

  Therefore, in the present embodiment, the angle of the upstream paper guides 103A and 103B with respect to the roller 102 is controlled using a matrix of moisture content and air permeability as shown in Table 2, that is, as the air permeability increases. By increasing the angle of the paper guide plate, the heating time for the paper P is secured, and the water vapor inside the paper is efficiently released. Thereby, the state (water content) of the sheet before fixing can be further optimized.

[Fifth Embodiment]
In addition, based on the image forming mode (printing mode) set by the image forming apparatus 200 in accordance with the moisture content of the paper P detected by the moisture detection sensor 211, the upstream side paper guide 103A, It is also preferable to control the angle of the 103B with respect to the roller 102.

  As described above, the toner blister is an abnormal image in which moisture inside the paper is heated during fixing and breaks through the toner image portion. For this reason, it does not occur in a character with a small area of the toner image portion or a monochrome print mode with a small amount of adhesion of the toner print portion. This is because when the toner adhesion amount is small, water vapor generated inside the toner image grows up to the toner surface and bursts, so that it is leveled by the residual heat after the fixing nip and does not become a toner blister.

  However, when the toner adhesion amount is large, the water vapor passes through the nip before rising to the surface of the toner layer, resulting in uneven gloss on the toner image surface.

  Therefore, in the present embodiment, the upstream paper guides 103A and 103B are used by using a matrix of paper moisture content and printing modes (monochrome printing mode, full color printing mode, mixed mode (full color / monochrome)) as shown in Table 3. By controlling the angle with respect to the roller 102, that is, by lowering the angle of the upstream paper guide 103 in the monochrome mode and by increasing the angle of the upstream paper guide 103 in the full color mode or mixed mode, the heating time for the paper P is ensured. In order to efficiently release water vapor inside the paper, the toner blisters are suppressed. Thus, by controlling the angle of the upstream paper guide 103 according to the image to be formed, stable quality can be obtained regardless of the image.

  In addition, by using the image forming apparatus 200 (FIG. 1) including the nipping and conveying apparatus 100 having the above-described configuration, it is possible to perform printing with less image defects with a simple configuration without the occurrence of blisters during fixing. Further, the image quality can be improved according to various paper types and image modes, and the stability and reliability of the image forming apparatus can be improved.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

100 Nipping and conveying apparatus 101 Frame 102A Upper roller (first roller)
102B Lower roller (second roller)
103, 103A, 103B upstream side paper guides 103A ₁ , 103B ₁ leading end (upstream side paper guide)
103A ₂ , 103B ₂ main body (upstream side paper guide)
104, 104A, 104B Downstream side paper guide 105 Heater (heating means)
106 Temperature sensors 107, 107A, 107B Auxiliary transport roller 108 Bearing 109 Outer arm 110 Inner arm 111 Support point 112 Bearing 113 Cam 114 Spring member 115 Lower frame 200 Image forming apparatus 200A Image forming section 200B Paper feeding section 201 Writing apparatuses 202Y, 202M , 202C, 202K Charging devices 203Y, 202M, 202C, 202K Developing devices 204Y, 204M, 204C, 204K Primary transfer devices 205Y, 205M, 205C, 205K Photoconductor 206 Fixing device 207 Fixing roller 208 Heating roller 208h Halogen heater 209 Fixing belt 210 Pressure roller 211 Moisture content detection sensor (moisture content detection means)
213 Intermediate transfer belt 214 Followed roller 215 Secondary transfer roller 216 Stacker 217 Paper transport unit 220 Paper feed tray 221 Pick roller 222 Transport roller N Fixing nip part P Paper (recording medium)
R1 transport path R2 reverse transport path

JP-A-2005-96948

Claims (7)

The first roller,
A second roller provided at a position facing the first roller and sandwiching and conveying the recording medium with the first roller;
Heating means for heating either the first roller or the second roller;
Moisture content detection means provided on the upstream side of the recording medium conveyance path with respect to the first roller and the second roller to detect the moisture content of the recording medium;
A paper guide plate for guiding the recording medium to the first roller and the second roller,
An nipping and conveying apparatus that controls an angle of the sheet guide plate with respect to the first roller and the second roller based on a detection result of a moisture content of the recording medium by the moisture content detecting unit. The paper guide plate includes at least a tip portion on the first roller or the second roller side, and a main body portion other than the tip portion,
The tip end portion is controlled to change an angle with respect to the main body portion so as to approach a roller side of the first roller or the second roller heated by the heating unit. Item 2. The nipping and conveying apparatus according to Item 1.   The nipping and conveying apparatus according to claim 1 or 2, wherein the moisture content detecting means is provided so as to be able to detect the moisture content of the recording medium on the image forming surface side of the recording medium.   The angle of the sheet guide plate with respect to the first roller and the second roller is controlled based on the moisture content detection result of the recording medium by the moisture detection means and the type of the recording medium. The clamping conveyance apparatus in any one of Claim 1 to 3.   The angle of the paper guide plate with respect to the first roller and the second roller is controlled based on the moisture content detection result of the recording medium by the moisture detection means and the air permeability of the recording medium. The nipping and conveying apparatus according to any one of claims 1 to 3.   The angle of the sheet guide plate with respect to the first roller and the second roller is controlled based on a detection result of the moisture content of the recording medium by the moisture detection means and an image forming mode. The clamping conveyance apparatus in any one of 1-3.   An image forming apparatus comprising the nipping and conveying apparatus according to claim 1.

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