JP2009091058A - Curl straightening device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curl straightening device capable of straightening curls of a recording material in a width direction without a skew or jamming, and an image forming device. <P>SOLUTION: The curl straightening device comprises a first curl straightening roller 93 arranged at one end from the width center of recording paper in a paper discharging path and having an outer diameter at the recording paper widthwise end side larger than the outer diameter at a center side, and a second curl straightening roller 94 arranged at the other end from the center in the recording paper width direction with the first curl straightening roller 93 in the recording paper width direction, and having an outer diameter at the recording paper widthwise end side larger than the outer diameter at the center side. An upper guide plate 91 and a lower guide plate 92 extend to an area where the first curl straightening roller 93 is opposed to the second curl straightening roller 94, and the first curl straightening roller 93 and the second curl straightening roller 94 are brought into contact with the upper guide plate 91 so as to form curl straightening nips. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a curl correcting apparatus and an image forming apparatus that correct curl of a recording material.

  A fixing nip is formed by contact between a heating roller containing a heat source such as a halogen lamp and a pressure roller pressed toward the heating roller, and the recording paper sandwiched between the fixing nips is heated while being pressed. An image forming apparatus including a fixing device that fixes a toner image formed on a recording sheet to the recording sheet by heating is known. The recording paper subjected to the fixing process in this way may be curled (curved) by being pressed or heated in the fixing nip.

  In recent years, as the recording paper, instead of the paper fixed in a posture in which the fiber extends along the paper width direction or the conveyance direction, the fiber extends along the oblique direction, or the fiber extending direction is Many things that are irregular are being used. When such a recording paper is used, as shown in FIG. 25, both ends in the paper width direction (arrow Y direction in the figure), which is a direction orthogonal to the transport direction (arrow X direction in the figure), are lifted from the center portion. Curl at both ends may occur.

  Patent Document 1 includes a reverse crown-shaped metal roller having an outer diameter that decreases from both ends toward the central portion downstream of the fixing device in the recording paper conveyance direction, and an elastic roller having a urethane foam portion. An image forming apparatus having a pair of conveying rollers is described.

The recording paper that has passed through the fixing device is guided by a pair of guide members, and is conveyed to a nip (hereinafter referred to as a curl correction nip) of a conveyance roller pair composed of an inverted crown-shaped metal roller and an elastic roller.
In the reverse crown-shaped metal roller, the peripheral speed of the end portion having a large outer diameter is higher than that of the central portion. Therefore, a force that pulls the recording paper conveyed to the curl correction nip outward in the paper width direction is applied. When the recording paper receives such a pulling force toward the outside in the paper width direction, the above-described curl at both ends can be corrected.

Japanese Patent No. 3754746

  However, when the curl correction nip is formed by the conveyance roller pair, the guide member pair cannot be extended to the nip of the conveyance roller pair, and a gap is generated in the conveyance direction between the curl correction nip and the guide member pair. End up. In the gap between the curl correction nip and the guide member pair, the behavior of the recording paper cannot be controlled. In particular, when a recording paper having an irregular fiber extending direction such as recycled paper is used, the curl amount may be greatly different between one end side and the other end side of the recording paper. As a result, the contact position with the curl conveyance roller pair differs in the paper width direction, which may cause skew or jam.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a curl correction apparatus and an image forming apparatus that can correct curl in the width direction of a recording material without causing skew or jam. Is to provide.

In order to achieve the above object, the invention according to claim 1 is directed to the recording caused by the heat treatment after passing through a fixing unit that heats the recording material carrying toner and fixes the toner image on the recording material. In the curl correction apparatus for correcting the curl of the material, a first guide member disposed to face a flat portion of the recording material in the recording material conveyance path after passing through the fixing unit, the first guide member, and the recording material conveyance A second guide member disposed oppositely across the path, and disposed on one end side from the center in the width direction of the recording material in the recording material conveyance path, and the outer diameter on the end side in the recording material width direction is set to the outer side of the center side. A first curl correction roller having a diameter larger than the diameter, and the first curl correction roller and the first curl correction roller arranged on the other end side from the center of the recording material width direction so as to be aligned with the recording material width direction. The outer diameter on the end side is A curl correcting roller pair for correcting curl of the recording material, and comprising the first curl correcting roller and the second curl correcting roller. A curl correction nip for correcting the curl of the recording material is formed by the first guide member and each curl correction roller in contact with the first guide member, and the second guide member is The first curl correction roller and the second curl correction roller are extended to a region facing each other.
According to a second aspect of the present invention, in the curl straightening device according to the first aspect, the opposite portion of the first guide member facing the first curl straightening roller and the second curl straightening roller facing portion follow the shape of the curl straightening roller. It is characterized by having such a shape.
According to a third aspect of the present invention, in the curl straightening apparatus according to the first or second aspect, a plurality of the curl straightening roller pairs are arranged in the recording material conveyance direction.
According to a fourth aspect of the present invention, in the curl straightening device according to any one of the first to third aspects, the first curl straightening roller and / or the second curl straightening roller can be moved in a direction perpendicular to the recording material conveyance direction. It is characterized by comprising.
According to a fifth aspect of the present invention, in the curl straightening device according to any one of the first to fourth aspects, the first curl straightening roller and the second curl straightening roller are provided with a step portion corresponding to the width of the recording material. It is a feature.
According to a sixth aspect of the present invention, in the curl correcting apparatus according to any one of the first to fifth aspects, the first curl correcting roller and the second curling unit are disposed in the vicinity of a central portion in the width direction of the recording material in the recording material conveyance path. In the vicinity of the curl correction roller, a recording material abutting member for bringing the central portion of the recording material toward the second guide member is provided.
According to a seventh aspect of the present invention, in the curl straightening device according to the sixth aspect, the abutting member is configured to bring the central portion of the recording material closer to the curl direction side of the recording material. is there.
According to an eighth aspect of the present invention, in the curl straightening apparatus according to the sixth or seventh aspect, the moving member is configured to be movable in a direction perpendicular to the recording material flat portion.
According to a ninth aspect of the present invention, in the curl straightening device according to any of the sixth to eighth aspects, the approach member is a driven roller.
According to a tenth aspect of the present invention, in the curl straightening device according to any of the sixth to eighth aspects, the approach member is a drive roller.
The eleventh aspect of the present invention is the curl straightening device according to any one of the sixth to tenth aspects, wherein the moving member is a roller member, and the thickness and / or curl of the recording material in the recording material conveyance path. Detection means for detecting the amount, and control means for controlling the drive of the roller member and / or the movement of the roller member in the direction perpendicular to the recording material plane portion based on the detection result of the detection means. It is characterized by having.
According to a twelfth aspect of the present invention, in the curl correction apparatus according to any one of the first to eleventh aspects, the first guide member and the second guide member are made of metal.
The invention according to claim 13 is the curl straightening device according to claim 12, wherein the metal is iron.
The invention according to claim 14 is a visible image forming unit that forms a visible image on a sheet-like recording member conveyed in a predetermined direction, a fixing unit that fixes the visible image on the recording member, 14. An image forming apparatus including a curl correcting unit that corrects curling of the recording member after passing through a fixing unit, wherein the curl correcting device according to claim 1 is used as the curl correcting unit. It is what.

According to the first to fourteenth aspects of the present invention, the first and second curl correction rollers have the outer diameter on the recording material width direction end portion side larger than the outer diameter on the recording material center side. The peripheral speed on the side becomes faster than that on the center side. Accordingly, the recording material conveyed to the curl correction nip formed by the first curl correction roller and the first guide member and conveyed to the curl correction nip formed by the second curl correction roller and the first guide member. At the other end side of the recording material, a pulling force is exerted on the recording material width direction outside, and the curling in the width direction of the recording material can be corrected.
Further, the second guide member and the first guide member are extended to a region where the first curl correction roller and the second curl correction roller are opposed to each other in the recording paper width direction, and the first guide member is connected to each curl correction roller. In contact with each other, a curl correction nip is formed by the first guide member and each of the curl correction rollers. Accordingly, the central portion of the recording material is guided to the curl correction nip by the first guide member and the second guide member, and both end portions of the recording material are also guided to the curl correction nip by the first guide member. Thus, since the recording material curled by the guide member can be guided to the curl correction nip, the behavior of the recording material entering the curl correction nip can be controlled by the second guide member and the first guide member. Therefore, it is possible to suppress the contact position of the recording material against the curl correction roller from greatly differing in the recording material width direction, and it is possible to suppress the occurrence of skew or jam.

Hereinafter, an electrophotographic copying machine as an image forming apparatus to which the present invention is applied will be described.
FIG. 1 is a schematic configuration diagram showing a copying machine according to the present embodiment. The copying machine includes a printer unit 1 that forms an image on recording paper, a paper feeding device 200 that supplies the recording paper P to the printer unit 1, a scanner 300 that reads a document image, and automatically feeds a document to the scanner 300. An automatic document feeder (hereinafter referred to as ADF) 400 is provided.

  The scanner 300 is placed on the contact glass 301 as the first traveling body 303 equipped with a document illumination light source or mirror and the second traveling body 304 equipped with a plurality of reflecting mirrors reciprocate. Scanning of a document (not shown) is performed. The scanning light sent out from the second traveling body 304 is condensed on the imaging surface of the reading sensor 306 installed behind the imaging lens 305 and then read as an image signal by the reading sensor 306.

  On the side surface of the housing of the printer unit 1, a manual feed tray 2 for manually placing the recording paper P to be fed into the housing, and a paper discharge tray 3 for stacking the recording paper P after image formation discharged from the housing. Is provided.

  FIG. 2 is an enlarged partial configuration diagram illustrating a part of the internal configuration of the printer unit (1). In the housing of the printer section (1), there is disposed a transfer unit 50 as transfer means for stretching an endless intermediate transfer belt 51 as a transfer body by a plurality of stretching rollers. The intermediate transfer belt 51 is made of a material in which carbon powder for adjusting electric resistance is dispersed in a polyimide resin with little elongation. Then, while being stretched by a driving roller 52, a secondary transfer backup roller 53, a driven roller 54, and four primary transfer rollers 55Y, 55Y, 55C, 55K, which are driven to rotate in the clockwise direction in the drawing by a driving means (not shown) By the rotation of the driving roller 52, it is moved endlessly in the clockwise direction in the figure. Note that the suffixes Y, C, M, and K attached to the ends of the symbols of the primary transfer roller indicate the members for yellow, cyan, magenta, and black. Hereinafter, the subscripts Y, C, M, and K attached to the ends of the symbols are the same.

  The intermediate transfer belt 51 is greatly curved at the portions where the intermediate transfer belt 51 is wound around the driving roller 52, the secondary transfer backup roller 53, and the driven roller 54, so that the intermediate transfer belt 51 is stretched in an inverted triangular posture with the bottom side directed vertically upward. ing. The belt upper stretch surface corresponding to the base of the inverted triangle extends in the horizontal direction. Above the belt upper stretch surface, four process units 10Y, 10C, 10M, and 10K are provided on the upper stretch surface. It arrange | positions so that it may align with a horizontal direction along the extending direction.

  In FIG. 1 described above, an optical writing unit 60 is disposed above the four process units 10Y, 10C, 10M, and 10K. Based on the image information of the original read by the scanner 300, the optical writing unit 60 drives four semiconductor lasers (not shown) by a laser control unit (not shown) to emit four writing lights L. Then, the drum-shaped photoconductors 11Y, 11C, 11M, and 11K serving as latent image carriers of the process units 10Y, 10C, 10M, and 10K are scanned in the dark by the writing light L, respectively. , K, electrostatic latent images for Y, C, M, and K are written.

  In this embodiment, the optical writing unit 60 performs optical scanning by deflecting laser light emitted from a semiconductor laser by a polygon mirror (not shown) and reflecting it with a reflection mirror (not shown) or passing it through an optical lens. Is used. Instead of such a configuration, an LED array that performs optical scanning may be used.

  FIG. 3 is an enlarged configuration diagram showing the process units 10Y and 10 for Y and C together with the intermediate transfer belt 51. As shown in FIG. The Y process unit 10Y includes a charging member 12Y, a charge eliminating device 13Y, a drum cleaning device 14Y, a developing device 20Y as developing means, a potential sensor 49Y, and the like around a drum-shaped photoconductor 11Y. And while these are hold | maintained with the casing which is a common holding body, it is attached and detached integrally as one unit with respect to a printer part.

  The charging member 12Y is a roller-like member that is rotatably supported by a bearing (not shown) while being in contact with the photoreceptor 11Y. The surface of the photoconductor 11Y is uniformly charged with, for example, the same polarity as that of Y toner by rotating in contact with the photoconductor 11Y while a charging bias is applied by a bias supply means (not shown). Instead of the charging member 12Y having such a configuration, a scorotron charger or the like that performs a uniform charging process in a non-contact manner on the photoconductor 11Y may be employed.

  A developing device 20Y in which a Y developer containing a magnetic carrier (not shown) and non-magnetic Y toner is contained in a casing 21Y has a developer conveying device 22Y and a developing unit 23Y. In the developing unit 23Y, a developing sleeve 24Y as a developer carrying member that is endlessly moved by being rotated by a driving unit (not shown) exposes a part of its peripheral surface to the outside through an opening provided in the casing 21Y. ing. As a result, a developing region is formed in which the photoconductor 11Y and the developing sleeve 24Y face each other with a predetermined gap.

  Inside the developing sleeve 24Y made of a non-magnetic hollow pipe-like member, a magnet roller (not shown) having a plurality of magnetic poles arranged in the circumferential direction is fixed so as not to rotate with the developing sleeve 24Y. The developing sleeve 24Y is driven to rotate while adsorbing the Y developer in the developer conveying device 22Y, which will be described later, to the surface by the magnetic force generated by the magnet roller, thereby pumping the Y developer from the developer conveying device 22Y. Then, the Y developer conveyed toward the developing area as the developing sleeve 24Y rotates, the doctor blade 25Y having the tip opposed to the surface of the developing sleeve 24Y with a predetermined gap, and the sleeve A doctor gap of 0.9 [mm] formed with the surface is entered. At this time, the layer thickness on the sleeve is regulated to 0.9 [mm] or less. When the developing sleeve 24Y is rotated and conveyed to the vicinity of the developing area facing the photoconductor 11Y, it receives a magnetic force of a developing magnetic pole (not shown) of the magnet roller and rises on the sleeve to become a magnetic brush. .

  For example, a developing bias having the same polarity as the charging polarity of the toner is applied to the developing sleeve 24Y by a bias supply unit (not shown). As a result, in the development region, non-development in which Y toner is electrostatically moved from the non-image portion side to the sleeve side between the surface of the development sleeve 24Y and the non-image portion (uniformly charged portion = background portion) of the photoreceptor 11Y. Potential acts. Further, a developing potential for electrostatically moving Y toner from the sleeve side toward the electrostatic latent image acts between the surface of the developing sleeve 24Y and the electrostatic latent image on the photoreceptor 11Y. The Y toner in the Y developer is transferred to the electrostatic latent image by the action of the developing potential, so that the electrostatic latent image on the photoreceptor 11Y is developed into the Y toner image.

  The Y developer that has passed through the developing area as the developing sleeve 24Y rotates is separated from the developing sleeve 24Y due to the influence of the repulsive magnetic field formed between the repelling magnetic poles provided in the magnet roller (not shown). The developer returns to the developer conveying device 22Y.

  The developer conveying device 22Y includes two first screw members 26Y, a second screw member 32Y, a partition wall interposed between the two screw members, a toner concentration detection sensor 45Y including a magnetic permeability sensor, and the like. The partition wall divides the first transport chamber, which is a developer transport section, in which the first screw member 26Y is accommodated, and the second transport chamber, which is a developer transport section in which the second screw member 32Y is accommodated. In the region facing both ends of the screw member in the axial direction, both transfer chambers are communicated with each other through an opening (not shown).

  The first screw member 26Y and the second screw member 32Y as the agitating / conveying members are respectively provided with a rod-like rotary shaft member whose both ends are rotatably supported by a bearing (not shown), and a spiral projection on the peripheral surface thereof. And a spiral blade. Then, as it is driven to rotate by a driving means (not shown), the Y developer is conveyed in the rotation axis direction by the spiral blade.

  In the first transport chamber in which the first screw member 26Y is accommodated, the Y developer is transported from the near side to the far side in the direction orthogonal to the drawing surface as the first screw member 26Y is driven to rotate. . And if it conveys to the edge part vicinity of the back | inner side of casing 21Y, it will approach into a 2nd conveyance chamber via the opening which is not provided in the partition wall.

  The above-described developing unit 23Y is formed above the second transfer chamber in which the second screw member 32Y is accommodated, and the second transfer chamber and the developing unit 23Y communicate with each other in the entire area of the opposing part. ing. As a result, the second screw member 32Y and the developing sleeve 24Y disposed obliquely above the second screw member 32Y face each other while maintaining a parallel relationship. In the second transport chamber, the Y developer is transported from the back side to the near side in the direction orthogonal to the drawing sheet as the second screw member 32Y is driven to rotate. In this transport process, the Y developer around the rotation direction of the second screw member 32Y is appropriately pumped up to the developing sleeve 24Y, and the developed Y developer is appropriately collected from the developing sleeve 24Y. Then, the Y developer transported to the vicinity of the near end of the second transport chamber in the drawing returns to the first transport chamber through an opening (not shown) provided in the partition wall.

  A toner concentration detection sensor 45Y as a toner concentration detection means including a magnetic permeability sensor is fixed to the lower wall of the first transfer chamber, and the toner concentration of the Y developer conveyed by the first screw member 26Y is lowered. And outputs a voltage according to the detection result. A control unit (not shown) replenishes an appropriate amount of Y toner into the first transfer chamber by driving a Y toner supply device (not shown) as necessary based on the output voltage value from the toner concentration detection sensor 45Y. As a result, the toner concentration of the Y developer, which has been lowered with the development, is recovered.

  The Y toner image formed on the photoreceptor 11Y is primarily transferred onto the intermediate transfer belt 51 at a Y primary transfer nip described later. The transfer residual toner that has not been primarily transferred onto the intermediate transfer belt 51 adheres to the surface of the photoreceptor 11Y after passing through the primary transfer process.

  The drum cleaning device 14Y cantilever-supports a cleaning blade 15Y made of, for example, polyurethane rubber, and the free end thereof is brought into contact with the surface of the photoreceptor 11Y. In addition, the brush tip side of the brush roller 16Y, which includes a rotating shaft member that is driven to rotate by a driving means (not shown) and an infinite number of conductive brushes erected on the peripheral surface thereof, is brought into contact with the photoreceptor 11Y. Yes. The transfer residual toner is scraped off from the surface of the photoreceptor 11Y by the cleaning blade 15Y and the brush roller 16Y. A cleaning bias is applied to the brush roller 16Y via a metal electric field roller 17Y that is in contact with the brush roller 16Y, and the tip of the scraper 18Y is pressed against the electric field roller 17Y. The transfer residual toner scraped off from the photoconductor 11Y by the cleaning blade 15Y and the brush roller 16Y passes through the brush roller 16Y and the electric field roller 17Y, and then is scraped off from the electric field roller 17Y by the scraper 18Y and is placed on the recovery screw 19Y. Fall. Then, after the recovery screw 19Y is driven to rotate, the recovery screw 19Y is discharged out of the casing, and then returned to the developer transport device 22Y via a toner recycling transport means (not shown).

  The surface of the photoreceptor 11Y, from which the transfer residual toner has been cleaned by the drum cleaning device 14Y, is neutralized by the neutralizing device 13Y including a neutralizing lamp, and is then uniformly charged again by the charging member 12Y.

  The potential of the non-image portion of the photoreceptor 11Y that has passed the optical writing position by the writing light L is detected by the potential sensor 49Y, and the detection result is sent to a control unit (not shown).

  Although the Y process unit 10Y has been described in detail, the process units (10C, M, K) of other colors have the same configuration as that of Y except that the color of the toner to be used is different. .

  In FIG. 2 shown above, the photoconductors 11Y, 11C, 11M, and 11K of the process units 10Y, 10C, 10M, and 10K are in contact with the upper stretched surface of the intermediate transfer belt 51 that is moved endlessly in the clockwise direction. Rotating to form primary transfer nips for Y, C, M, and K. On the back side of the primary transfer nips for these Y, C, M, and K, the above-described primary transfer rollers 55Y, 55C, 55M, and 55K are in contact with the back surface of the intermediate transfer belt 51. A primary transfer bias having a polarity opposite to the charging polarity of the toner is applied to each of the primary transfer rollers 55Y, 55C, 55M, 55K by a bias supply unit (not shown). Due to this primary transfer bias, a primary transfer electric field is formed in the primary transfer nips for Y, C, M, and K to electrostatically move the toner from the photoreceptor side to the belt side. The Y, C, M, and K toner images formed on the photoreceptors 11Y, 11C, 11M, and 11K are primary for Y, C, M, and K as the photoreceptors 11Y, 11C, 11M, and 11K rotate. When entering the transfer nip, primary transfer is performed by sequentially superimposing on the intermediate transfer belt 51 by the action of the primary transfer electric field and nip pressure. As a result, a four-color superimposed toner image (hereinafter referred to as a four-color toner image) is formed on the front surface (loop outer peripheral surface) of the intermediate transfer belt 51. Instead of the primary transfer rollers 55Y, 55C, 55M, 55K, a conductive brush to which a primary transfer bias is applied, a non-contact type corona charger, or the like may be employed.

  As shown in FIG. 3, a secondary transfer roller 56 is disposed below the intermediate transfer belt 51. The secondary transfer roller 56 is driven to rotate counterclockwise in the drawing by a driving means (not shown). A secondary transfer nip is formed in contact with the front surface. Then, on the back side of the secondary transfer nip, a secondary transfer backup roller 53 that is electrically grounded is wound around the intermediate transfer belt 51.

  A secondary transfer bias having a polarity opposite to the charging polarity of the toner is applied to the secondary transfer roller 56 by a bias supply unit (not shown), whereby 2 is placed between the secondary transfer roller 56 and the grounded secondary transfer backup roller 53. A next transfer electric field is formed. The four-color toner image formed on the front surface of the intermediate transfer belt 51 enters the secondary transfer nip as the intermediate transfer belt 51 moves endlessly.

  In FIG. 1 described above, the paper feeding device 200 is fed with a paper feeding cassette 201 for storing the recording paper P, and a paper feeding roller 202 for feeding the recording paper P stored in these paper feeding cassettes 201 out of the cassette. A plurality of separation roller pairs 203 for separating the recording paper P one by one, a plurality of conveyance roller pairs 205 for conveying the separated recording paper P along the delivery path 204, and the like are provided. The sheet feeding device 200 is disposed directly below the printer unit 1 as shown in the figure. The feeding path 204 of the paper feeding device 200 is connected to the paper feeding path 70 of the printer unit 1. As a result, the recording paper P delivered from the paper feed cassette 201 of the paper feed device 200 is sent into the paper feed path 70 of the printer unit 1 via the feed path 204.

  A registration roller pair 71 is disposed near the end of the paper feed path 70 of the printer unit 1, and the recording paper P sandwiched between the rollers can be synchronized with the four-color toner image on the intermediate transfer belt 51. Send to the secondary transfer nip. In the secondary transfer nip, the four-color toner images on the intermediate transfer belt 51 are collectively transferred to the recording paper P due to the influence of the secondary transfer electric field and the nip pressure, and combined with the white color of the recording paper P, Become. The recording paper P on which the full-color image is formed in this way is separated from the intermediate transfer belt 51 when discharged from the secondary transfer nip.

  On the left side of the secondary transfer nip in the figure, a conveyor belt unit 75 is provided that moves the endless paper conveyor belt 76 endlessly in the counterclockwise direction in the figure while being stretched by a plurality of stretching rollers. . The recording paper P separated from the intermediate transfer belt 51 is transferred to the upper stretched surface of the paper conveying belt 76 and conveyed toward the fixing device 80.

  The recording paper P sent into the fixing device 80 is sandwiched in a fixing nip formed by a heating roller 81 containing a heat source such as a halogen lamp (not shown) and a pressure roller 82 pressed toward the heating roller 81. The full color image is sent to the outside of the fixing device 80 while being fixed on the surface by being heated while being pressurized.

  On the surface of the intermediate transfer belt 51 after passing through the secondary transfer nip, a slight amount of secondary transfer residual toner that has not been transferred to the recording paper P adheres. The secondary transfer residual toner is removed from the belt by a belt cleaning device 57 that is in contact with the front surface of the intermediate transfer belt 51.

  In FIG. 1 described above, a switchback device 85 is disposed below the fixing device 80. When the recording paper P discharged from the fixing device 80 reaches the conveyance path switching position by the swingable switching claw 86, depending on the swing stop position of the switching claw 86, the paper discharge roller pair 87 or the switchback device. Sent to 85. When the paper is sent toward the paper discharge roller pair 87, the paper is discharged out of the apparatus and then stacked on the paper discharge tray 3.

  On the other hand, when it is sent toward the switchback device 85, it is turned upside down by the switchback conveyance by the switchback device 85 and then conveyed toward the registration roller pair 71 again. Then, it again enters the secondary transfer nip, and a full-color image is formed on the other side.

  The recording paper P manually fed onto the manual feed tray 2 provided on the side surface of the housing of the printer unit 1 passes through the manual feed roller 72 and the manual separation roller pair 73 and then toward the registration roller pair 71. Sent. The registration roller pair 71 may be grounded, or a bias may be applied to remove paper dust from the recording paper P.

  When copying a document with the copying machine according to the present embodiment, first, the document is set on the document table 401 of the automatic document feeder 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass 301 of the scanner 300, and the automatic document feeder 400 is closed and pressed. Thereafter, when a start switch (not shown) is pressed, when the document is set on the automatic document feeder 400, the document is sent into the contact glass 301. Then, the scanner 300 is driven and reading scanning by the first traveling body 303 and the second traveling body 304 is started. At substantially the same time, driving of the transfer unit 50 and each color process unit 10Y, C, M, K starts. Furthermore, the feeding of the recording paper P from the paper feeding device 200 is also started. When recording paper P not set in the paper feed cassette 201 is used, the recording paper P set on the manual feed tray 2 is sent out.

  As a method of forming an image according to the size of the recording paper P, there are a one-end reference method and a center reference method. Specifically, recording paper P of various sizes can be stored in the paper feed cassette 201 and the manual feed tray 2. Further, the toner image forming means, which is a visible image forming means including the process units 10Y, 10C, 10M, 10K, the optical writing unit 60, the transfer unit 50, and the like corresponds to the recording paper P of various sizes. A toner image of a size can be formed. In order to appropriately form toner images of various sizes on the recording paper P of various sizes at predetermined positions, the position of the recording paper P in the paper width direction in the transport path and each photoconductor It is necessary to match the toner image forming position in the drum axis direction with respect to 11Y, C, M, and K. In the one-end reference method, regardless of the size of the recording paper P, the recording paper P is transported in such a posture that one end in the paper width direction of the recording paper P is positioned on one end side in the paper width direction of the transport path. Further, the writing start position in the main scanning direction (the laser deflection direction and the same as the drum axis direction) with respect to each of the photoconductors 11Y, 11C, 11K is set to one end side in the drum axis direction regardless of the size of the recording paper P. To. On the other hand, in the center reference method, the recording paper P is transported in such a posture that the center in the paper width direction of the recording paper P is positioned at the center in the paper width direction of the transport path regardless of the size of the recording paper P. Further, a writing process is performed on each of the photoreceptors 11Y, 11C, 11M, and 11K with the center in the main scanning direction as the center in the paper width direction of the toner image.

  Of these methods, the printer employs the center reference method. Therefore, the recording paper P is transported in a posture in which the center in the paper width direction is positioned at the center in the paper width direction of the transport path regardless of the size.

  In an image forming apparatus that fixes a toner image on a recording paper by thermal fixing, the recording paper is held on the recording paper when the toner carrying surface of the recording paper is sandwiched in a fixing nip between a heating roller 81 and a pressure roller 82 and is thermocompression-bonded. The amount of water evaporated differs between the front surface and the back surface, and between the toner carrying portion and the toner non-carrying portion. As a result, the moisture content varies depending on the position of the recording paper, and curling occurs.

  In recent years, recycled paper is often used as recording paper. Recycled paper has the property that the fiber direction is not uniform compared to conventional paper. Therefore, a so-called curl at both ends that curls in the width direction of the recording paper occurs.

  For this reason, in the present embodiment, a curl correction device capable of correcting the above-described curl at both ends is provided downstream of the fixing device 80 in the recording paper conveyance direction.

FIG. 4 is a schematic perspective view of the curl correction apparatus 100, and FIG. 5 is a front view of the curl correction apparatus 100.
As shown in the figure, the curl correction apparatus 100 includes an upper guide plate 91 as a first guide member, a lower guide plate 92 as a second guide member, a first curl correction roller 93, a second curl correction roller 94, and a counter member as an offset member. A roller 95 is provided.

The upper guide plate 91 is disposed on the heating roller 81 side, and extends from the fixing nip exit to a position where the first curl correction roller 93 and the second curl correction roller 94 are disposed. The lower guide plate 92 is disposed so as to face the upper guide plate 91 across the paper discharge path. Similar to the upper guide plate 91, the arrangement positions of the first curl correction roller 93 and the second curl correction roller 94 from the fixing nip exit. It extends to.
On the fixing nip side of the upper guide plate 91, an inclined surface 91a inclined upward by about 30 ° is formed toward the heating roller 81 side, and the gap between the upper guide plate 91 and the lower guide plate 92 is fixed. It expands toward the nip exit. Accordingly, even when the leading edge of the recording paper is wound around the heating roller to some extent when passing through the fixing nip, the leading edge of the recording paper P is guided to a region where the upper guide plate 91 and the lower guide plate 92 are opposed to each other. can do.

  At least the guide surfaces for guiding the recording paper P of the upper guide plate 91 and the lower guide plate 92 are preferably formed of a material having a small friction coefficient. Specifically, metal materials such as iron, aluminum, and copper, and heat resistant resins such as PC (polycarbonate) and PET (polyethylene terephthalate) can be used. In particular, it is preferable that the upper guide plate 91 and the lower guide plate 92 are formed of metal, and by forming the metal, friction with the recording paper P can be reduced and deformation due to heat generated by the heating roller 81 can be prevented. it can. Moreover, the apparatus can be made inexpensive by forming the upper guide plate 91 and the lower guide plate 92 with inexpensive iron.

The first curl correction roller 93 is provided in the vicinity of the width direction end of the lower guide plate 92. The second curl correction roller 94 is arranged at the end of the lower guide plate 92 opposite to the side where the first curl correction roller 94 is arranged so as to be aligned with the first curl correction roller 93 in the recording paper width direction. Is provided. A drive shaft 96 is passed through the first curl correction roller 93 and the second curl correction roller 94, and a driven pulley 103 is fixed to one end of the drive shaft 96. A timing belt 101 is wound around the driven pulley 103. The timing belt 101 is also wound around a driving pulley 102 fixed to a driving shaft 105a of the curl correction driving motor 105.
The driving force of the curl correction drive motor 105 is transmitted to the first curl correction roller 93 and the second curl correction roller 94 through the drive pulley 102, the timing belt 101, the driven pulley 103, and the drive shaft 96, and the first curl correction roller 94 is transmitted. The roller 93 and the second curl correction roller 94 are driven to rotate.

The first curl correction roller 93 and the second curl correction roller 94 have a substantially conical shape whose outer diameter decreases toward the center of the recording paper P being conveyed. Opposing portions of the upper guide plate 91 between the first curl correction roller 93 and the second curl correction roller 94 are recessed in a substantially conical shape so as to follow the shapes of the curl correction rollers 93 and 94, respectively. The first curl correction roller 93 and the second curl correction roller 94 are in contact with the recesses of the upper guide plate 91 to form a curl correction nip.
The axial lengths of the first curl correction roller 93 and the second curl correction roller 94 are set so that the minimum sheet that can be handled by the copying machine is sandwiched between the curl correction nips.

  A roller shaft 95a of the counter roller 95 is rotatably attached to a pair of attachment arms 91b provided on the surface opposite to the recording paper guide surface of the upper guide plate 91 with a predetermined distance in the width direction. The counter roller 95 contacts the lower guide plate 92 through a hole provided in the center of the location where the first curl correction roller 93 and the second curl correction roller 94 of the upper guide plate 91 oppose each other in the width direction of the recording paper P. It touches.

  The curl direction of the recording paper P is determined in advance by the position of the heating roller 81 and the shape of the fixing nip. In this copying machine, the fixing nip is a downward nip that curves toward the pressure roller, so the recording paper is Curls to the heating roller side. When the curling direction of the recording paper is on the pressure roller side, the opposing roller is brought into contact with the upper guide plate, and the first and second curl correction rollers are brought into contact with the lower guide plate 92. In this case, the lower guide plate 92 functions as a first guide plate, and the upper guide plate 91 functions as a second guide plate.

  The recording paper P that has passed through the fixing nip is guided by the upper guide plate 91 and the lower guide plate 92 and conveyed to the curl correction nip. At this time, when both end curls are generated in the recording paper P, both ends thereof are guided by the inclined surface of the upper guide plate 91. Then, the recording paper P is sandwiched between the upper guide plate 91 and the lower guide plate 92 in the vertical direction, and the recording paper is guided to the curl correction nip with the curling of the recording paper P being corrected to some extent.

  In the case of the recording paper P with non-uniform fiber directions such as recycled paper, the curl amount on the first curl correction roller side of the recording paper P may be different from the curl amount on the second curl correction roller side. For example, when the first curl correction roller side of the recording paper P is hardly curled and the second curl correction roller side of the recording paper is largely curled, the curl of the recording paper P is not corrected by the guide plate. When transported to each curl correction nip, the first curl correction roller side of the recording paper P is smoothly transported to the curl correction nip, but the second curl correction roller side of the recording paper is transferred to the second curl correction roller 94. After hitting, it is conveyed to the curl correction nip. As a result, the timing of entering the curl correction nip is shifted between the first curl correction roller side and the second curl correction roller side of the recording paper P. As a result, there is a risk that skew, wrinkles, etc. may occur, and in some cases, jams may occur.

  However, in the present embodiment, as shown in FIG. 4, the upper guide plate 91 and the lower guide plate 92 extend to a facing region where the first curl correction roller 93 and the second curl correction roller 94 oppose each other in the paper width direction. The recording paper P during curl correction is guided by the upper and lower guide plates 91 and 92 by the curl correction nip. Therefore, the recording sheet P is sandwiched between the upper guide plate 91 and the lower guide plate 92, and the recording sheet P is corrected so that the curl of the recording sheet P is uniform to some extent in the width direction and the curvature radius of the curl is increased. P can enter the curl correction nip. As a result, the timing of entering the curl correction nip on the first curl correction roller side and the second curl correction roller side of the recording paper P can be made substantially the same, and the occurrence of skew, wrinkles, jams, etc. is suppressed. be able to.

  The recording paper P after passing through the fixing nip slides on the upper guide plate 91 and the lower guide plate 92, but at least the guide surfaces of the lower guide plate 92 and the upper guide plate 91 that guide the recording paper P have a small friction coefficient. Since it is made of a material, it is possible to suppress an image that has not yet been fixed to the recording paper P from being disturbed by rubbing against the lower guide plate 92 or the upper guide plate 91.

  Further, when the recording paper P enters the curl correction nip formed at both ends in the recording paper width direction, the central portion of the recording paper P enters the nip formed by the lower guide plate 92 and the opposing roller 95, and recording is performed. The paper P is brought close to the lower guide plate 92 by the facing roller 95. As described above, the recording paper P is moved toward the lower guide plate by the facing roller 95, so that both ends of the recording paper P can be along the circumferential surface of the curl correction roller.

  In this copying machine, the central portion of the recording paper is moved toward the lower guide plate by the opposing roller as a roller member. For example, the central portion of the guide surface of the upper guide plate is upstream from the downstream side in the recording paper conveyance direction. A guide protrusion may be provided such that the height from the guide surface increases toward the side, and the central portion of the recording paper may be moved toward the lower guide plate by the guide protrusion.

  When the recording paper enters the curl correction nip and the nip formed by the lower guide plate 92 and the counter roller 95, the first curl correction roller 93, the second curl correction roller 94, and the counter roller 95 cause the recording paper to be recorded. The end of P in the width direction is forcibly curled in the direction opposite to the curled direction. Further, since the first and second curl correction rollers 93 and 94 have a substantially conical shape in which the outer diameter decreases toward the center side of the recording paper P being conveyed, the end side is closer to the end side than the center side. The peripheral speed is faster. Therefore, both ends of the recording paper P sandwiched between the curl correction nips are pulled outward. The curling of the recording paper P can be corrected by pulling the recording paper P outward and forcibly curling the recording paper P in the direction opposite to the curled direction.

  The length of the opposing roller 95 in the recording paper width direction is preferably (1/3) or less of the width of the guide plate. When this exceeds (1/3), the contact area between the recording paper and the opposing roller 95 increases, and the opposing roller 95 and the recording paper P are not yet completely fixed to the recording paper due to the friction between the opposing roller 95 and the recording paper P. There is a high risk that the image will be disturbed. Further, the portion that is pressed against the lower guide plate 92 of the recording paper P by the opposing roller 95 increases, and when the recording paper is pulled outward in the width direction by the curl correction nip, the recording paper cannot be stretched well in the width direction. This is because the recording paper may be wrinkled.

  In addition, the inclination angle of the peripheral surfaces of the first curl correction roller 93 and the second curl correction roller 94 with respect to the drive shaft 96 is preferably 30 ° to 45 °. By setting the inclination angle to 30 ° to 45 °, it is possible to deal with both thick papers that tend to have a large curl curvature radius and plain papers that tend to have a small curl curvature radius.

  Further, the lower guide plate 92 and the upper guide plate 91 are fastened to the positions where the first curl correction roller 93 and the second curl correction roller 94 are arranged, and from the positions where the first curl correction roller 93 and the second curl correction roller 94 are arranged. It is preferable not to further extend downstream in the recording material conveyance direction. This is because curl does not occur on the recording paper after passing through the curl correction nip, and it is not necessary to correct the curl with the upper guide plate 91 and the lower guide plate 92. Then, the lower guide plate 92 and the upper guide plate 91 are fastened to the positions where the first curl correction roller 93 and the second curl correction roller 94 are disposed, and the lengths of the lower guide plate 92 and the upper guide plate 91 are minimized. By fastening to, the conveyance part of the apparatus can be made compact. Further, the material cost can be reduced, and the cost of the apparatus can be reduced.

  Further, the opposing portions of the upper guide plate 91 facing the first curl correction roller 93 and the second curl correction roller 94 are recessed in a substantially conical shape so as to follow the shapes of the curl correction rollers 93 and 94, respectively. Accordingly, the vicinity of both end portions of the recording paper P can be pressed against the peripheral surface of the curl correction roller, respectively, and it is possible to more reliably apply a force outward in the width direction to the recording paper.

  Next, a modified example of the curl correction apparatus will be described.

[Modification 1]
First, the curl straightening device of Modification 1 will be described.
FIG. 6 is a perspective view of the curl correction apparatus 100A of the first modification.
As shown in the figure, in the curl correcting apparatus 100A of the first modification, a plurality of curl correcting roller pairs including a first curl correcting roller 93 and a second curl correcting roller 94 are arranged in the recording paper conveyance direction. As a result, a force outward in the width direction can be applied to the recording paper twice, and the curling of the recording paper can be more reliably removed. For example, the discharge side first curl arranged on the paper discharge side is inclined with respect to the drive shaft of the peripheral surfaces of the fixing side first curl correction roller 93b and the fixing side second curl correction roller (not shown) arranged on the fixing side. The inclination angle of the peripheral surfaces of the curl correction roller 93a and the discharge-side second curl correction roller 94a with respect to the drive shaft is made smaller. As a result, the difference in peripheral speed between the end side and the center side of the first and second curl correction rollers on the fixing side is the peripheral speed between the end side and the center side of the first and second curl correction rollers on the discharge side. It becomes smaller than the speed difference. Therefore, the curl correction nip on the fixing side does not pull the recording paper strongly in the width direction, and the curl can be corrected stepwise by pulling the recording paper strongly in the width direction on the discharge side curl correction nip. Become.
This is only an example, and the inclination angle of the peripheral surface of the curling correction roller on the fixing side and the discharge side may be the same, or the inclination angle of the peripheral surface of the discharge side curl correction roller may be the same. The inclination angle of the peripheral surface of the roller may be increased so that the recording paper is strongly pulled in the width direction at the curl correction nip on the fixing side.

  In FIG. 6, the opposing roller 95 is disposed between the first curl correcting roller 93b on the fixing side and the second fixing curl roller on the fixing side (not shown). You may arrange | position between the roller 93b and the fixing side 2nd curl correction roller 94b not shown. Further, an opposing roller 95 may be disposed between the fixing side curl correction roller pair and the discharge side curl correction roller pair. Further, between the first curl correction roller 93b on the fixing side and a second curl correction roller (not shown), and between the first curl correction roller 93b on the discharge side and the second curl correction roller 94b on the discharge side. You may arrange | position the opposing roller 95, respectively. Further, the opposing roller 95 may be disposed upstream of the fixing-side curl correction roller in the recording paper conveyance direction.

[Modification 2]
Next, a curl correction apparatus according to Modification 2 will be described.
FIG. 7 is a diagram illustrating the characteristic points of the curl correction apparatus according to the second modification.
In the curl straightening device according to the second modification, the curl straightening roller is movable in the axial direction (width direction of the recording paper).
In the following description, the first curl correction roller 93 will be described, but the second curl correction roller 94 has the same configuration as the first curl correction roller.
As shown in FIG. 7A, the drive shaft 96 is provided with notches 96a and 96b at locations corresponding to the size of the recording paper P. The first curl correction roller 93 is provided with a hole 93c for attaching the engagement pin 93b and a fitting portion 93a into which the engagement pin 93b is fitted. Then, the first curl correction roller 93 is slid and the fitting portion 93a is aligned with the notch portion 96a (96b) provided in the drive shaft 96 corresponding to the size of the recording paper to be conveyed. Then, the engaging pin 93 b is fitted into the fitting portion 93 a and the notch portion 96 a (96 b), and the first curl correction roller 93 is fixed to the drive shaft 96. Thereby, it is possible to cope with various paper sizes without lengthening the curl correction roller in the axial direction.

  Further, as shown in FIG. 7B, the first curl correction roller 93 is provided with a hook portion 93e having a claw portion 93d, and this claw portion 93d is engaged with the notch portion 96a (96b) of the drive shaft 96. Thus, the first curl correction roller 93 can be arranged at a position corresponding to the size of the recording paper to be conveyed. A portion of the hook portion 93e protrudes from the side surface of the first curl correction roller 93. By pulling up this protruding portion with respect to the drive shaft, the engagement between the claw portion 93d and the notch portion is released. 1 The curl correction roller 93 can be slid.

  The mechanism for moving the first curl correction roller and the second curl correction roller in the axial direction is not limited to the above, and the mechanism may be moved using the following mechanism.

FIG. 8 is a perspective view showing another embodiment of the curl correction apparatus according to the second modification.
FIG. 9 is a view of another embodiment of the curl straightening device of Modification 2 as seen from the lower guide plate side.
As shown in FIG. 8, the upper guide plate 91 is formed with notches extending in the axial direction (recording paper width direction) in regions facing the first and second curl correction rollers 93 and 94, respectively. As shown in FIG. 10, the first and second upper slide plates 115a and 115b are slidably fixed. Each upper slide plate 115a, 115b is formed with a recess along the circumferential surface of the curl correction roller.

  An upper slide plate position adjustment shaft 112 is rotatably fixed to the upper guide plate 91. Screw grooves are formed in the vicinity of both ends of the upper slide plate position adjusting shaft 112. As shown in FIG. 11, first and second upper slide plate position adjusting arms 113 and 114 are respectively provided in the respective screw grooves. It is screwed. The screw groove into which the first upper slide plate position adjusting arm 113 is screwed is cut in the opposite direction to the screw groove into which the second upper slide plate position adjusting arm 113 is screwed. As a result, when the upper slide plate position adjustment shaft 112 rotates and the first upper slide plate position adjustment arm 113 moves inward, the second upper slide plate position adjustment arm 114 also moves inward, and the first upper slide plate position adjustment arm 113 moves inward. When the slide plate position adjustment arm 113 moves outward, the second upper slide plate position adjustment arm 114 also moves outward. A first upper slide plate 115 a is attached to the tip of the first upper slide plate position adjusting arm 113. A second upper slide plate 115 b is attached to the tip of the second upper slide plate position adjustment arm 114.

  Further, as shown in FIG. 9, notches are respectively formed at both ends of the portion of the lower guide plate 92 where the curl correction roller is disposed, and the first and first notches are formed in the notches as shown in FIG. 2 The lower slide plates 121a and 121b are slidably fixed. Cutouts along the peripheral surfaces of the curl correction rollers 93 and 94 are formed at the ends of the lower slide plates 121a and 121b.

  A curl correction roller position adjustment shaft 122 is rotatably fixed on the lower guide plate 92, and thread grooves are formed near both ends of the curl correction roller position adjustment shaft 122. The first and second curl correction roller position adjusting arms 123 and 124 are screwed into the screw grooves, respectively. The screw groove into which the first curl correction roller position adjusting arm 123 is screwed is cut in the opposite direction to the screw groove into which the second curl correction roller position adjusting arm 124 is screwed. Accordingly, when the curl correction roller position adjustment shaft 122 rotates and the first curl correction roller position adjustment arm 123 moves inward, the second curl correction roller position adjustment arm 124 also moves inward, and the first first When the first curl correction roller position adjustment arm 123 moves outward, the second curl correction roller position adjustment arm 124 also moves outward.

  12 is a cross-sectional view taken along the dotted line in FIG. 9 as seen from the center side. As shown in the figure, the tip of the second curl correction roller position adjusting arm 124 is formed with a bifurcated lower slide plate mounting portion 124a, which is fixed to the lower slide plate 121b. Similarly, in the first curl correction roller position adjusting arm 123, a lower slide plate mounting portion 123a having a bifurcated tip is fixed to the first lower slide plate 121a.

  FIG. 13 is an enlarged cross-sectional view of the vicinity of the second curl correction roller. As shown in the figure, the drive shaft 96 has a groove 96a extending over its entire length, and a connecting slide member 125 that connects the second curl correction roller position adjusting arm and the second curl correction roller 94 to the groove 96a. It is slidably fitted in the axial direction. A roller engagement protrusion 125 a is provided at the outer end portion of the second connecting slide member 125, and is engaged with an engagement groove provided on the inner peripheral surface of the second curl correction roller 94. Further, an arm engagement protrusion 125b is formed at the inner end of the connecting slide member 125. The arm engagement protrusion 125b is inserted into the through hole of the slide plate mounting portion 124a together with the drive shaft 96 and separated into two. The lower slide plate mounting portion 124a is engaged.

  One ends of the upper slide plate position adjustment shaft 112 and the curl correction roller position adjustment shaft 122 are connected to the position adjustment drive mechanism 110.

FIG. 14 is a schematic configuration diagram of a main part of the position adjustment drive mechanism 110, and FIG. 15 is a perspective view of the position adjustment drive mechanism 110.
As shown in the figure, a handle shaft 111b to which a handle gear 111a and a handle 111 are fixed is rotatably supported on the support plate 110a. The handle gear 111a meshes with an upper slide plate position adjustment gear 112a fixed to the end of the upper slide plate position adjustment shaft 112. Further, the curl correction roller position adjustment gear 122a fixed to the curl correction roller position adjustment shaft 122 is engaged with the upper slide plate position adjustment gear 112a. A gear 131 is formed at the end of the curl correction roller position adjusting shaft 122. Further, a stopper 130 formed with teeth that mesh with the gear 131 at the tip is fixed to the support plate 110a in a swingable manner. The upper slide plate position adjustment gear 112a and the curl correction roller position adjustment gear 122a are gears having the same size and shape.

When the first and second curl correction rollers 93 and 94 are moved to a position corresponding to the size of the recording paper P on which an image is to be formed, the stopper 130 is swung so that the teeth formed on the tip of the stopper 130 The meshing with the gear 131 is released.
Next, when the handle 111 is rotated and the handle gear 111a is rotated, the upper slide plate position adjustment gear 112a is rotated and the upper slide plate position adjustment shaft 112 is rotated. When the upper slide plate position adjusting shaft 112 rotates, the first and second upper slide plate position adjusting arms 113 and 114 move inward or outward, respectively. As the first upper slide plate position adjustment arm 113 moves, the first upper slide plate 115a fixed to the first upper slide plate position adjustment arm 113 moves inward or outward. Further, as the second upper slide plate position adjusting arm 114 moves, the second upper slide plate 115b fixed to the second upper slide plate position adjusting arm 113 moves inward or outward.

  When the upper slide plate position adjustment gear 112a rotates, the curl correction roller position adjustment gear 122a meshing with the upper slide plate position adjustment gear 112a rotates in the opposite direction to the upper slide plate position adjustment gear 112a. The position adjustment shaft 122 rotates in the opposite direction to the upper slide plate position adjustment shaft 112. In this embodiment, even if the curl correction roller position adjustment shaft 122 rotates in the direction opposite to the upper slide plate position adjustment shaft 112, the first and second curl correction roller position adjustment arms 123 and 124 are 2 The screw groove of the upper slide plate position adjusting shaft 112 is cut so as to move in the same direction as the upper slide plate position adjusting arms 113 and 114. Specifically, the direction in which the thread groove into which the first curl correction roller position adjusting arm 123 is screwed is reversed from the direction in which the thread groove into which the first upper slide plate position adjusting arm 113 is screwed is cut. To do. As a result, even if the curl correction roller position adjustment shaft 122 rotates in the direction opposite to the upper slide plate position adjustment shaft 112, the first and second curl correction roller position adjustment arms 123 and 124 move to the first and second upper slides. It moves in the same direction as the plate position adjusting arms 113 and 114.

  When the first curl correction roller position adjustment arm 123 moves due to the rotation of the curl correction roller position adjustment shaft 122, the first lower slide plate 121a fixed to the first curl correction roller position adjustment arm 123 moves, and the first A first connecting slide member (not shown) engaged with the curl correction roller position adjusting arm 123 slides in the groove 96 a of the drive shaft 96. And the 1st curl correction roller 93 engaged with the 1st connection slide member not shown slides to an axial direction.

  As the second curl correction roller position adjustment arm 124 moves, the first lower slide plate 121b fixed to the second curl correction roller position adjustment arm 124 moves and the first curl correction roller position adjustment arm 124 moves. The second connecting slide member 125 engaged with the slider slides in the groove 96a of the drive shaft. And the 2nd curl correction roller 94 engaged with the 2nd connection slide member 125 slides to an axial direction.

  The user uses the first upper slide plate position adjustment arm 113 on the basis of the marking for each sheet size provided on the upper guide plate 91 shown in FIG. 8, and the marking corresponding to the size of the recording paper P forming the image. To match. Then, when the first upper slide plate position adjustment arm 113 is set to the ruled line corresponding to the size of the recording paper P forming the image, the stopper 130 is swung to curl the teeth formed at the tip of the stopper 130. The adjusting shaft is prevented from rotating by meshing with the gear 131 formed at the end of the correction roller position adjusting shaft.

  The mechanism described above is suitable for an image forming apparatus such as a high-speed printing machine that forms a large amount of images on the same size recording paper and the paper size does not change frequently, and is used in offices and homes. When the paper size on which an image is formed changes frequently as in the image forming apparatus, it is preferable to attach a drive motor instead of the handle so that the position of the curl correction roller can be automatically adjusted.

  In addition, a plurality of curl correction devices having different axial positions of the first curl correction roller and the second curl correction roller are provided, and the recording paper that has passed through the fixing nip is switched by a switching unit (not shown) to correspond to the paper size. You may comprise so that it may convey to a correction apparatus. Further, the curl correcting device may be configured to be detachable from the apparatus main body, and when the paper size is changed, it may be replaced with a curl correcting device corresponding to the paper size.

[Modification 3]
Next, a curl correction apparatus according to Modification 3 will be described.
FIG. 16 is a front view of a curl correction apparatus 100C of Modification 3.
As shown in the figure, the curl correcting apparatus 100C of the third modification is provided with first and second curl correcting rollers 93 and 94 provided with stepped portions corresponding to the width of the recording paper.
As shown in FIG. 17A, for example, when the A3 sheet is conveyed to the curl correction nip, the end of the recording sheet P hits the side surface of the outermost step of the curl correction roller. As a result, the A3 sheet conveyed to the curl correction nip is guided and conveyed to the stepped portion, and the recording sheet can be conveyed without causing a skew or the like. Further, since the diameter of the curl correction roller at the contact portion with the recording paper (A to C in the figure) is larger on the outer side, a difference in peripheral speed is generated, and a force for pulling the recording paper outward is generated. It can be corrected.
As shown in FIG. 17B, for example, when A4 paper is conveyed to the curl correction nip, the end of the recording paper hits the side surface of the second step as counted from the outside, By being guided, skew is suppressed. Further, since the diameter of the curl correction roller at the contact portion with the recording paper (D and E in the figure) is larger on the outer side, a difference in peripheral speed is generated, and a force for pulling the recording paper to the outside is generated. It can be corrected.

  Also, as shown in FIG. 18, by forming an inclined surface between the stepped portions, the recording paper comes into contact with the inclined surface, and it is possible to generate a force for pulling the recording paper outward more reliably. .

[Modification 4]
Next, a curl correction apparatus according to Modification 4 will be described.
FIG. 19 is a perspective view of a curl correction apparatus 100D of Modification 4.
As shown in the figure, the curl straightening device 100D of Modification 4 is configured such that the opposing roller 95 is movable in the direction perpendicular to the recording paper flat surface.
As shown in the figure, the rotating shaft 144 is rotatably attached to shaft attaching portions 145a and 145b formed in parallel with the upper guide plate 91 in the axial direction. Further, a first arm portion 146a and a second arm portion 146b are fixed to the rotating shaft 144, and a counter roller 95 is rotatably attached to the tips of the arm portions 146a and 146b.
A driven gear 143 is fixed to one end of the rotating shaft 144, and the driven gear 143 meshes with the drive gear 142 of the contact / separation motor 141.

  When the contact / separation motor 141 is driven, the rotation shaft 144 rotates and the arm portions 146a and 146b rotate around the rotation shaft 144, so that the opposing roller 95 contacts and separates from the lower guide plate 92.

  Depending on the thickness and type of the recording paper, the curl amount and the strength of the paper also differ. For example, if the recording paper is thick, there will be no problems such as tearing the recording paper even if the force to pull the recording paper to the outside is somewhat strong, but in the case of recording paper with low strength such as thin paper, If the pulling force is strong, the recording paper may be torn. As the position of the facing roller 95 is closer to the lower guide plate 92, the recording paper can be curved and the recording paper can be caused to follow the peripheral surface of the curl correction roller, thereby increasing the force with which the recording paper is pulled outward. it can. On the other hand, when the position of the opposing roller 95 is separated from the lower guide plate 92, the amount of bending of the recording paper is reduced, the number of contact points with the peripheral surface of the correction roller near the end of the recording paper is reduced, and the recording paper is pulled outward. You can weaken the power.

  Therefore, the contact / separation motor is controlled based on the type of recording paper, and the position of the opposing roller in the direction perpendicular to the recording paper plane is changed. As a result, it is possible to apply an appropriate outward pulling force to the recording paper in accordance with the type of paper and the curl amount, and to prevent the recording paper from being damaged. For example, a paper thickness detection sensor or the like as a recording material detection unit is provided in the recording paper conveyance path, and the contact / separation motor is controlled based on the detection result so as to be perpendicular to the recording paper plane portion of the opposing roller. Change position.

[Modification 5]
Next, a curl correction apparatus of Modification 5 will be described.
FIG. 20 is a perspective view of a curl correction apparatus 100E of Modification 5.
As shown in the figure, a counter drive motor 151 is provided to rotate the counter roller 95.

  By rotating the counter roller 95, resistance when entering the nip between the counter roller 95 and the lower guide plate 92 can be reduced. As a result, the recording paper P can be conveyed at high speed. This is because the difference between the circumferential speed of the opposing roller 95 when the leading edge of the recording paper P enters the nip between the opposing roller 95 and the lower guide plate 92 and the conveyance speed of the recording paper P can be reduced. It is possible to smoothly enter the nip between the facing roller 95 and the lower guide plate 92. Therefore, even if the recording paper P is conveyed at a high speed, a large speed difference between the recording paper end and the central portion when the leading edge of the recording paper P enters the nip between the opposing roller 95 and the lower guide plate 92. Can be prevented, and jamming and wrinkling can be suppressed.

  Further, by setting the rotation speed of the counter roller 95 to be slower than the rotation speed of the curl correction roller, a speed difference occurs between the central portion of the recording paper and the end portion of the recording paper. A force for pulling the recording paper outward can be generated, and the curling of the recording paper can be more reliably corrected.

  Further, as shown in FIG. 21, a line sensor 150 serving as a curl amount detection unit for detecting the curl amount of the recording paper is provided in the vicinity of the fixing nip exit. Then, based on the curl amount detected by the line sensor 150, the driving speed of the counter roller 95 is determined, and the optimum pulling force is controlled by controlling the pulling force of the recording paper generated by the counter roller 95 and the curl correction roller. It is also possible to apply force to the recording paper.

FIG. 22 is a block diagram showing a part of an electric circuit of a control unit as control means.
The control unit 160 includes a CPU that is a calculation unit, a ROM and a RAM that are storage units. The memory of the device stores a table 1 and a table 2 as shown in FIG.

FIG. 23 is a control flow for determining the rotation speed of the opposing roller.
First, the control unit 160 receives paper size information (S1), and stores the paper size information in a temporary storage area such as a RAM. Next, the recording paper passing through the fixing nip exit is detected by the line sensor 150 (S3), and the curl amount is calculated based on the detection result (S4). Specifically, the curl amount C is detected from the curl height H, the curl detection time T, and the table 2 shown in FIG. Regarding the curl detection time T, when the number of sensors of the line sensor 150 that has detected the recording paper is equal to or greater than a predetermined number, the control unit 160 determines that the curl has been detected, and starts time measurement. When the number of sensors that detect the recording paper is less than the predetermined number, the curl detection time T is detected by ending the time measurement. The curl height H is detected based on the number of sensors that detect the recording paper. When the curl amount C is calculated in this manner, the driving speed of the facing roller 95 is determined based on the curl amount C, the paper size, and the table 1 (S5), and the control unit 160 has the determined driving speed. In this manner, the driving of the counter drive motor 151 is controlled (S6, S7).

  In this way, by controlling the rotation speed of the counter roller 95 based on the curl amount and the paper size, it is possible to give an optimum tension to the recording paper and to correct the curling of the recording paper satisfactorily.

In the above description, the rotation speed of the counter roller 95 is determined based on the paper size information and the curl amount. However, the rotation speed of the counter roller may be determined based on the paper thickness and the curl amount of the paper. . Further, the rotational speed of the opposing roller may be determined only from the paper thickness information, or the rotational speed of the opposing roller may be determined based on the paper size, the paper thickness, and the curl amount.
In the above description, the rotation speed of the counter roller 95 is controlled. For example, the counter roller 95 has the same conveying speed as the fixing device, and the rotation speeds of the first and second curl correction rollers are set to the sheet size information. And may be determined based on the curl amount. In this case, the rotation speeds of the first and second curl correction rollers are set faster than the rotation speed of the counter roller.
Further, the rotational speed of the opposing roller 95 is determined based on the paper size information and the curl amount, but the vertical position of the opposing roller with respect to the recording paper plane portion is determined based on the paper size information and the curl amount. May be. Further, based on the paper size information and the curl amount, both the position of the opposing roller in the direction perpendicular to the recording paper plane and the rotational speed of the opposing roller 95 may be determined.

As described above, according to the curl correcting apparatus of the present embodiment, the upper guide as the first guide member that faces the flat portion of the recording paper as the recording material in the paper discharge path as the conveying path of the recording paper as the recording material after passing through the fixing device. A plate 91 and a lower guide plate 92 as a second guide member disposed opposite to the upper guide plate 91 across the paper discharge path are provided. A first curl correction roller 93 disposed on one end side from the center in the width direction of the recording paper in the paper discharge path and having an outer diameter on the end side in the recording paper width direction larger than the outer diameter on the center side; It is arranged so as to be aligned with the other end side from the center in the recording paper width direction and in a straight line with the first curl correction roller 93 in the recording paper width direction, and the outer diameter on the recording paper width direction end side is larger than the outer diameter on the central side. A second curl correction roller 94 having a diameter and a curl correction roller pair for correcting the recording paper curl are provided.
By having such a configuration, the peripheral speed on the end side of the first and second curl correction rollers becomes faster than that on the center side. Accordingly, the recording paper conveyed to the curl correction nip formed by the first curl correction roller and the upper guide plate and conveyed to the curl correction nip formed by the second curl correction roller and the upper guide plate. At the other end of the recording paper, a pulling force acts outward in the recording paper width direction, and the curling in the width direction of the recording paper can be corrected.
Then, the first curl correction roller and the second curl correction roller are brought into contact with the upper guide plate, and the curl correction nip for correcting the curl of the recording material is formed by the upper guide plate and each of the curl correction rollers, respectively. At the same time, the lower guide plate is extended to a region where the first curl correction roller and the second curl correction roller face each other. With this configuration, the central portion of the recording paper is guided to the curl correction nip by the upper guide plate and the lower guide plate, and both end portions of the recording paper are also guided to the curl correction nip by the upper guide plate. In this way, since the recording paper curled by the guide plate can be guided to the curl correction nip, the behavior of the recording paper entering the curl correction nip can be controlled by the lower guide plate and the upper guide plate. Therefore, it is possible to suppress the contact position of the recording paper against the curl correction roller from being greatly different in the recording paper width direction, and it is possible to suppress the occurrence of skew or jam.

  Further, the facing portion of the upper guide plate 91 facing the first curl correction roller 93 and the facing portion of the second curl correction roller 94 are shaped so as to follow the shape of the curl correction roller. With this configuration, the vicinity of the end of the recording paper can be pressed against the circumferential surface of the curl correction roller, and a force for pulling the recording paper outward in the recording paper width direction can be generated more reliably.

  In addition, since a plurality of curl correction roller pairs are arranged in the recording material conveyance direction, the curling of the recording paper can be corrected a plurality of times, and the curling of the recording paper can be corrected more reliably.

  In addition, since the first curl correction roller 93 and / or the second curl correction roller 94 are configured to be movable in a direction orthogonal to the recording sheet conveyance direction, it is possible to deal with recording sheets of various width sizes.

  Further, by providing the first curl correction roller 93 and the second curl correction roller 94 with a step portion corresponding to the width of the recording paper, the end portion of the recording paper entering the curl correction nip is abutted against the side surface of the step portion. Can be transported. Thereby, the skew of the recording paper can be suppressed, and the recording paper can be accurately discharged to a predetermined position on the paper discharge tray 3.

  A recording paper shifting member that moves the central portion of the recording paper toward the lower guide plate in the vicinity of the center in the width direction of the recording paper in the discharge path and in the vicinity of the first curl correction roller 93 and the second curl correction roller 94. Provide. Accordingly, the recording paper can be along the peripheral surfaces of the first and second curl correction rollers, and the contact portion between the recording paper and the peripheral surfaces of the first and second curl correction rollers can be widened. Thereby, the peripheral speed difference at the end of the recording paper can be increased, and the force acting outward can be increased. As a result, the curl of the recording paper can be reliably removed.

  In addition, since the recording paper shifting member is configured to be movable in the direction perpendicular to the recording material flat portion, the width of the recording paper along the peripheral surfaces of the first and second curl correction rollers can be controlled, and the recording paper The force pulled outwards can be controlled. As a result, it is possible to generate an optimal tension on the recording paper according to the curl amount of the recording paper and the type of the recording paper.

  Further, by using the driven member as a driven roller, it is possible to prevent rubbing against the recording paper and to suppress image disturbance on the recording paper.

  Further, by using the driving member as the driving roller, the resistance when the leading edge of the recording paper enters the moving member is reduced, and even if the paper is transported at a high speed, a large speed difference may occur between the end portion and the central portion. The occurrence of jams and wrinkles can be suppressed. Further, if the rotational speed is made slower than the rotational speeds of the first curl correction roller and the second curl correction roller, a peripheral speed difference can be generated between the curl correction roller and the drive roller, and the recording paper is moved outward. A pulling force can be generated. Thereby, the curl of the recording paper can be corrected reliably.

  Further, a line sensor as a detecting means for detecting the curl amount of the recording paper in the paper discharge path, and the driving of the opposing roller 95 as the roller member and / or the recording paper flat portion of the opposing roller based on the detection result of the line sensor. And a control unit which is a control means for controlling the movement in the vertical direction. With such a configuration, it is possible to apply an optimum tensile force according to the paper type and the curl amount to the recording paper, and it is possible to correct the curling of the recording paper satisfactorily.

  In addition, by forming the upper guide plate and the lower guide plate with metal, friction with the recording paper can be reduced, the image on the recording paper can be prevented from being disturbed, and the heat roller heats the guide. It is possible to suppress the deformation of the plate.

  In particular, the apparatus can be made inexpensive by forming the upper guide plate and the lower guide plate with inexpensive iron.

  Further, in the copying machine as the image forming apparatus of the present embodiment, a visible image forming unit that forms a visible image on a sheet-like recording member that is conveyed in a predetermined direction, and a fixing that fixes the visible image on the recording member. By using the above-mentioned curl correction device as a curling correction unit that corrects curling in the width direction of the recording paper after passing through the fixing device and the fixing device, the recording paper without curling can be discharged. it can.

1 is a schematic configuration diagram showing a copier according to an embodiment. FIG. 3 is a partially enlarged configuration diagram illustrating a part of an internal configuration of a printer unit in the copier. FIG. 3 is an enlarged configuration diagram illustrating a process unit for Y and C together with an intermediate transfer belt in the printer unit. The schematic perspective view of a curl correction apparatus. The front view of a curl correction apparatus. The perspective view of the curl correction apparatus of the modification 1. FIG. The figure which shows the feature point of the curl correction apparatus of the modification 2. The perspective view which shows another embodiment of the curl correction apparatus of the modification 2. FIG. The figure which looked at the same curl correction apparatus from the lower guide plate side. The figure which shows the structure of the 1st curl correction roller vicinity of the same curl correction apparatus. The figure which shows the state which screwed together with the upper guide plate position adjustment arm and the upper guide plate position adjustment axis | shaft of the same curl correction apparatus. The figure which looked at the cross section cut with the dotted line of FIG. 9 from the center part side. The principal part expanded sectional view of the 2nd curl correction roller vicinity of the same curl correction apparatus. The principal part schematic block diagram of the position adjustment drive mechanism of the same curl correction apparatus. The position adjustment drive mechanism perspective view of the curl correction apparatus. The front sectional view of the curl straightening device of modification 3. The figure explaining the mode of contact | abutting with the recording paper of the 1st curl correction roller of the curl correction apparatus. The figure which shows other embodiment of the same curl correction apparatus. The perspective view of the curl correction apparatus of the modification 4. FIG. The perspective view of the curl correction apparatus of the modification 5. FIG. The figure which provided the line sensor in the fixing nip exit of the curl correction apparatus. The block diagram which shows a part of electric circuit of the control part of the same curl correction apparatus. The control flowchart of the curl straightening device. The figure which shows the look-up table stored in the memory of a control part. The perspective view which shows the recording paper which caused both-ends curl.

Explanation of symbols

10Y, C, M, K: Process unit 80: Fixing device 81: Heating roller 82: Pressure roller 91: Upper guide plate 92: Lower guide plate 93: First curl correction roller 94: Second curl correction roller 95: Opposing Roller 96: Drive shaft 110: Position adjustment drive mechanism 111: Handle 112: Upper slide plate position adjustment shaft 113: First upper slide plate position adjustment arm 114: Second upper slide plate position adjustment arm 122: Curl correction roller position adjustment shaft 123: First curl correction roller position adjustment arm 124: Second curl correction roller position adjustment arm 125: Connection slide member 130: Stopper 150: Line sensor 200: Paper feed device 201: Paper feed cassette

Claims (14)

In a curl correcting apparatus for correcting curling of the recording material caused by the heat treatment after passing through fixing means for fixing the toner image on the recording material by subjecting the recording material carrying toner to heat treatment,
A first guide member arranged to face the flat portion of the recording material in the recording material conveyance path after passing through the fixing means, and a second guide arranged to face the first guide member and the recording material conveyance path. Members,
A first curl correction roller disposed on one end side from the center in the width direction of the recording material in the recording material conveyance path, and having an outer diameter on the recording material width direction end portion side larger than the outer diameter on the center side; The first curl correction roller is disposed on the other end side from the center of the recording material width direction so as to be aligned with the first curl correction roller in the recording material width direction. A second curl correction roller having a large diameter, and a curl correction roller pair for correcting curl of the recording material,
Curl correction for correcting the curl of the recording material with the first guide member and each curl correction roller by bringing the first curl correction roller and the second curl correction roller into contact with the first guide member. A curl correction apparatus, wherein each nip is formed and the second guide member extends to a region where the first curl correction roller and the second curl correction roller are opposed to each other. The curl correction apparatus according to claim 1.
An anti-curl correcting apparatus characterized in that the opposing part of the first guide member facing the first anti-curl roller and the opposing part of the second anti-curl roller are shaped along the shape of the anti-curl roller. The curl correction apparatus according to claim 1 or 2,
A curl correcting apparatus, wherein a plurality of the curl correcting roller pairs are arranged in a recording material conveying direction. In the curl correction apparatus according to any one of claims 1 to 3,
A curl correction apparatus configured to be capable of moving the first curl correction roller and / or the second curl correction roller in a direction perpendicular to a recording material conveyance direction. In the curl correction apparatus according to any one of claims 1 to 4,
A curl correction apparatus, wherein the first curl correction roller and the second curl correction roller are provided with a step portion corresponding to the width of the recording material. In the curl correction apparatus according to any one of claims 1 to 5,
The central portion of the recording material is moved toward the second guide member in the vicinity of the central portion in the width direction of the recording material in the recording material conveyance path and in the vicinity of the first curl correction roller and the second curl correction roller. A curl correction apparatus provided with a recording material gathering member. The curl correction apparatus according to claim 6.
The curl correcting apparatus, wherein the offset member is configured to bring the central portion of the recording material closer to the curl direction side of the recording material. The curl correction apparatus according to claim 6 or 7,
A curl correction apparatus, wherein the offset member is configured to be movable in a direction perpendicular to the recording material flat surface portion. The curl correction apparatus according to any one of claims 6 to 8,
An anti-curl device characterized in that the abutting member is a driven roller. The curl correction apparatus according to any one of claims 6 to 8,
A curl straightening device, wherein the approach member is a drive roller. The curl correction apparatus according to any one of claims 6 to 10,
The approach member is a roller member,
Detection means for detecting the thickness and / or curl amount of the recording material in the recording material conveyance path, and driving of the roller member and / or the recording material of the roller member based on the detection result of the detection means A curl correction apparatus comprising: control means for controlling movement in a direction perpendicular to the flat surface portion. The curl correction apparatus according to any one of claims 1 to 11,
The curl correction apparatus, wherein the first guide member and the second guide member are made of metal. The curl correction apparatus according to claim 12,
The curl correction apparatus, wherein the metal is iron. Visible image forming means for forming a visible image on a sheet-like recording member conveyed in a predetermined direction, fixing means for fixing the visible image on the recording member, and the recording after passing through the fixing means In an image forming apparatus provided with a curl correcting means for correcting curl of a member,
An image forming apparatus using the curl correcting apparatus according to claim 1 as the curl correcting means.

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