JP2016164644A - Image forming apparatus and curve correction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus and a curve correction device that can correct a curve of a recording medium that can be generated in opposite directions with a simple configuration.SOLUTION: An image forming apparatus 10 comprises: a fixing device 200; a belt member 410 that conveys a sheet in contact with its outer peripheral surface 412; a roll member 440 that forms a nip part N20 into which the sheet is inserted with the belt member 410; a pressure pad 460 that presses the belt member 410 against a contact surface 442 of the roll member 440 to form a first curve N22 at the nip part N20; and a pressure member 470 that presses the belt member 410 against the contact surface 442 to form a second curve N24 at the nip part N20. The first curve N22 and the second curve N24 are directed opposite to each other.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus and a curvature correcting apparatus.

  Patent Document 1 includes a fixing device that fixes toner after transfer onto a sheet, and a curl removing device that removes curl from the sheet discharged from the fixing device. There is described an image forming apparatus having one roller and a rigid second roller disposed at a position to press the first roller, and the second roller having a cooling structure. .

  In Patent Document 2, a sheet conveying unit that conveys a sheet, an image forming unit that forms a toner image according to an image signal, and the image forming unit formed on the sheet conveyed by the sheet conveying unit. A transfer means for transferring the toner image; a fixing means for fixing the toner image on the paper by heating and pressurizing the paper on which the toner image has been transferred by the transfer means; A curl correcting means for correcting the curl of the paper, wherein the fixing means curls the paper in different directions according to the thickness of the paper, and the curl correcting means is relative to the fixing means. First curl correcting means for correcting the curl of the paper curled in the first direction, which is the direction in which the thick paper is curled, and the paper curled in the second direction opposite to the first direction An image forming apparatus comprising: a second curl correcting unit disposed on a downstream side in a sheet conveying direction by the sheet conveying unit with respect to the first curl correcting unit for correcting curl. ing.

  Patent Document 3 discloses an image forming unit for forming an image on a recording material, and a fixing unit for fixing the image to the recording material by applying heat and pressure to the recording material on which the image is formed by the image forming unit. A first belt member that conveys the recording material on which an image has been fixed by the fixing unit, and an inner periphery of the first belt member, and the recording material on which the image has been fixed by the fixing unit. Cooling that has a curved portion that is curved in a direction opposite to that in the conveyance direction and that cools the recording material conveyed by the first belt member via the first belt member in a region including the curved portion. An image forming apparatus is provided that includes a body and a pressing member that presses the recording material conveyed by the first belt member against the curved portion side of the cooling body.

  Patent Document 4 discloses a fixing member that heats and melts a toner image and fixes the toner image on a recording medium, a pressure member that forms a nip portion that is pressurized by the fixing member and transports the recording medium, and the fixing device. A moving mechanism that moves the pressure member relative to the member to increase or decrease the pressure in the nip portion; and a nip portion disposed downstream of the nip portion in the recording medium conveyance direction. A curl correction mechanism for imparting to the recording medium a curl in a direction opposite to the curl direction of the recording medium sent from the recording medium; and a variable means for varying the amount of the reverse curl imparted to the recording medium by the curl correction mechanism; And the variable means varies the amount of curl in the reverse direction according to the pressure of the nip portion that is increased or decreased by the moving mechanism.

JP 2008-81268 A JP 2009-249169 A JP 2009-161347 A JP 2011-191607 A

  The present invention is compared with an image forming apparatus that includes a first curvature correction device that forms a first curvature and a second curvature correction device that forms a second curvature that is opposite to the first curvature. An object of the present invention is to provide an image forming apparatus and a curvature correcting apparatus capable of correcting the curvature of a recording medium that may occur in different directions with a simple configuration.

According to a first aspect of the present invention, there is provided a fixing device for fixing a toner image on a recording medium, and a conveying member for conveying the recording medium in which the toner image is fixed by the fixing device and contacting an outer peripheral surface. And an endless conveying member, and a contact region forming member that forms a sandwiched region in which a recording medium is sandwiched between the contact surface and the transport member. A first curve forming member that is in contact with the inner peripheral surface of the transport member and that forms the first curve in the sandwiched region by pressing the transport member against the contact surface; It is in contact with the inner peripheral surface of the transport member, and is disposed at a position different from the first curve forming member in the transport direction, which is the direction in which the recording medium is transported. By pressing the A second bending member to form a second curved,
And the first curve and the second curve are opposite to each other.

  The present invention according to claim 2 further includes position changing means for changing a position of the second bending forming member with respect to the sandwiching region forming member, wherein the position changing means includes at least the first bending and Between the position where the second curve is formed and the position where the first curve is formed and the second curve is not formed, the second curve forming member with respect to the sandwiching region forming member The image forming apparatus according to claim 1, wherein the position is changed.

  According to a third aspect of the present invention, the sandwich region forming member is elastically deformable and has a hardness higher than that of the first curve forming member and a hardness lower than that of the second curve forming member. Item 3. The image forming apparatus according to Item 1 or 2.

  According to a fourth aspect of the present invention, the first curve forming member is disposed upstream of the second curve forming member in the transport direction and contacts the inner peripheral surface in the transport direction. The image forming apparatus according to claim 1, wherein a length of the image forming apparatus is longer than that of the second curve forming member.

  5. The image forming apparatus according to claim 1, wherein the fixing device further includes a cooling device that fixes the toner image on the recording medium using at least heat and cools the recording medium. It is.

  According to a sixth aspect of the present invention, a toner image is fixed to a recording medium which is formed by two fixing members coming into contact with each other and is moving in a fixing sandwiching area which is a sandwiching area of the recording medium. The fixing device to be fixed and the two correction members are in contact with each other, and the recording medium on which the toner image is fixed by the fixing device is passed through the correction pinching region that is a region for sandwiching the recording medium. The curving straightening device for correcting the curving of the recording medium, and a transport path used for transporting the recording medium from the fixing device to the curving straightening device. An image forming apparatus having a symmetrical shape with respect to a fixing nipping region and the conveyance path.

  According to a seventh aspect of the present invention, there is provided a conveying member that conveys a recording medium in which a toner image is fixed by a fixing device and is in contact with an outer peripheral surface, the conveying member being band-shaped and endless, and the outer peripheral A contact surface that contacts the surface, and a contact region forming member that forms a sandwich region where the recording medium is sandwiched between the contact surface and the transport member, and an inner peripheral surface of the transport member The conveying member is pressed against the contact surface to contact the first curve forming member that forms the first curve in the sandwiched area and the inner circumferential surface of the conveying member, and recording is performed. It is arranged at a position different from the first curve forming member in the transport direction, which is the direction in which the medium is transported, and presses the transport member against the contact surface, so that the second region A second curve forming member for forming a curve; The a, wherein the first bending and said second bending a bending straightening device are opposite to each other.

  According to the first aspect of the present invention, the first curvature correcting device that forms the first curvature and the second curvature correcting device that forms the second curvature that is opposite to the first curvature, respectively. It is possible to provide an image forming apparatus capable of correcting the curvature of a recording medium that may occur in different directions with a simple configuration as compared with the image forming apparatus provided.

  According to the second aspect of the present invention, as compared with an image forming apparatus in which the second curve is always formed in the sandwiched area, the curve can be corrected according to the type of the recording medium.

  According to the third aspect of the present invention, the first curve and the second curve which are formed in the same direction in the image forming apparatus having the same hardness of the first curve forming member and the second curve forming member. These curves can be opposite to each other.

  According to the fourth aspect of the present invention, for example, a large curvature that is likely to occur in a recording medium such as thick paper is corrected on the upstream side in the recording medium conveyance direction, and a small curvature that is likely to occur in a recording medium such as plain paper is corrected. Correction can be performed on the downstream side in the conveyance direction of the recording medium.

  According to the fifth aspect of the present invention, the recording medium heated by the fixing can be cooled faster than the image forming apparatus that does not have the cooling device.

  According to the sixth aspect of the present invention, the curve formed by the fixing device that forms the first curve and the second curve that are opposite to each other is symmetrical to the shape of the fixing device in which the curve is formed. It is possible to provide an image forming apparatus capable of correcting curvature by shape.

  According to the seventh aspect of the present invention, the first curvature correcting device that forms the first curvature and the second curvature correcting device that forms the second curvature that is opposite to the first curvature, respectively. As compared with the case where it is provided, it is possible to provide a curvature correcting device that can correct the curvature of a recording medium that may occur in different directions with a simple configuration.

1 is a diagram illustrating a configuration of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of a toner image forming unit included in the image forming apparatus illustrated in FIG. 1. FIG. 2 is a diagram illustrating a configuration of a fixing device and a configuration of a curvature correcting device included in the image forming apparatus illustrated in FIG. 1. FIG. 6 is a diagram illustrating a configuration of a fixing device and a configuration of a curvature correcting device included in an image forming apparatus according to a second embodiment of the present invention. FIG. 4A illustrates the operation of the curvature correcting device illustrated in FIG. 4, and FIG. 4A is a diagram illustrating the curvature correcting device in a state where the first curvature and the second curvature are formed in the correction nip. FIG. 4B is a diagram showing a state in which the first curve is formed in the correction nip and the second curve is not formed. FIG. 5 is a block diagram illustrating a control unit included in an image forming apparatus according to a second embodiment of the present invention. It is a flowchart explaining control of the curvature correction apparatus shown by FIG. FIG. 6 is a diagram illustrating a configuration of a fixing device and a configuration of a curvature correcting device included in an image forming apparatus according to a third embodiment of the present invention. FIG. 9A illustrates an operation of the curvature correcting apparatus illustrated in FIG. 8, and FIG. 9A is a diagram illustrating the curvature correcting apparatus in a state where the first curvature and the second curvature are formed in the correction nip. FIG. 9B is a diagram showing a state where the first curve is formed in the correction nip and the second curve is not formed.

  Next, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 shows an image forming apparatus 10 according to a first embodiment of the present invention. As shown in FIG. 1, the image forming apparatus 10 includes an image forming apparatus main body 12, and the image forming apparatus main body 12 is formed with a discharge port 14 for discharging a sheet used as a recording medium.

  A conveyance path 700 for conveying paper is formed in the image forming apparatus main body 12. In the image forming apparatus main body 12, for example, in order from the upstream side in the paper transport direction along the transport path 700, for example, two paper feed devices 600 and 620, and the paper feed device 600 and An image forming unit 100 for forming a toner image to be transferred and fixed on a sheet supplied from one of the sheet feeding devices 620, and a toner image formed by the image forming unit 100 and transferred to the sheet. A fixing device 200 for fixing on a sheet and a curvature correcting device 400 for correcting the curvature of the sheet on which the toner image is fixed by the fixing device 200 are arranged.

  The paper feeding device 600 includes a paper storage unit 602 that stores paper, and a delivery device 604 that sends the uppermost paper stored in the paper storage unit 602 to the conveyance path 700. A paper storage unit 622 that stores paper, and a sending-out device 624 that feeds the uppermost paper stored in the paper storage unit 622 to the conveyance path 700.

  The paper storage unit 602 and the paper storage unit 622 can store different types and sizes of paper. In the following description, it is assumed that plain paper is stored in the paper storage unit 602, and that thick paper thicker than plain paper is stored in the paper storage unit 622. For example, when a fixing device 200 is used to fix a toner image on different types of paper such as different thicknesses, different orientations and different strength curves may occur during fixing depending on the type of paper. The curvature correcting device 400 has different conditions for correcting the curvature of the paper according to the type of paper in order to satisfactorily correct the curvature with different sizes and orientations depending on the type of paper. Is desirable.

  The image forming unit 100 includes photosensitive drums 112Y, 112M, 112C, and 112K that are used as image carriers, and yellow toner images and magenta toner images are formed on the surfaces of the photosensitive drums 112Y, 112M, 112C, and 112K. , A yellow toner image forming unit 110Y, a magenta toner image forming unit 110M, a cyan toner image forming unit 110C, and a black toner image forming unit 110K that respectively form a cyan toner image and a black toner image. Details of the yellow toner image forming unit 110Y, the magenta toner image forming unit 110M, the cyan toner image forming unit 110C, and the black toner image forming unit 110K will be described later.

  Further, the image forming unit 100 includes a transfer device 130, and the transfer device 130 includes an intermediate transfer belt 132. The intermediate transfer belt 132 is used as a transfer body to which a toner image is transferred, and rotates in the direction of arrow a shown in FIG. Further, the toner images formed on the photosensitive drums 112Y, 112M, 112C, and 112K are transferred to the intermediate transfer belt 132 so as to overlap each other, and the toner images transferred so as to overlap are transferred from the paper storage unit 602 to the conveyance path. Further, the image is further transferred onto the sheet conveyed by using 700.

  The fixing device 200 is a device that fixes the toner image transferred onto the paper onto the paper using at least heat. Details of the fixing device 200 will be described later.

  The curvature correcting device 400 is a device that corrects the curvature of a sheet that has been curved due to, for example, heat applied from the fixing device 200. Details of the curvature correcting device 400 will be described later.

  The conveyance path 700 is used for conveying a sheet from either the sheet feeding device 600 or the sheet feeding device 620 toward the image forming unit 100, and for conveying the sheet from the image forming unit 100 to the fixing device 200. Used to convey the sheet from the fixing device 200 to the curvature correcting device 400, and used to discharge the sheet whose curvature is corrected by the curvature correcting device 400 to the outside of the image forming apparatus main body 12. ing.

  Further, an operation panel 800 used as an operation unit for operating the image forming apparatus 10 is mounted on the front surface of the image forming apparatus main body 12 (the front side of the sheet in FIG. 1). By operating the operation panel 800, for example, whether an image is formed on a sheet stored in the sheet storage unit 602 or an image is formed on a thick sheet stored in the sheet storage unit 622 is input. Made.

  FIG. 2 shows toner image forming units 110Y, 110M, 110C, and 110K. The toner image forming units 110Y, 110M, 110C, and 110K have the same configuration in which the color of the toner to be used and the color of the image to be formed are different from each other. As shown in FIG. 2, the toner image forming unit 110 charges the surface of the photosensitive drum 112 and the surface of the photosensitive drum 112 charged by the charging device 114 is irradiated with light to form a latent image. The latent image forming device 116 to be formed, the developing device 118 for developing the latent image formed on the surface of the photosensitive drum 112 by the latent image forming device 116 with toner, and the toner image transferred to the intermediate transfer belt 132 And a cleaning device 122 that cleans the surface of the photosensitive drum 112 after the cleaning.

  FIG. 3 shows the fixing device 200 and the curvature correcting device 400. As shown in FIG. 3, the fixing device 200 includes a belt member 210. The belt member 210 is used as a conveying member that conveys the paper P on which the toner image I is formed by the image forming unit 100, and is belt-shaped and endless. Further, the belt member 210 moves so as to rotate in the arrow c direction shown in FIG. As a material of the belt member 210, for example, a flexible resin or the like can be used.

  The fixing device 200 further includes a roll member 240. The roll member 240 is a curved surface, has a contact surface 242 that is a surface that contacts the outer peripheral surface 212 of the belt member 210, and corresponds to a sandwiching region in which a sheet is sandwiched between the contact surface 242 and the belt member 210. It is used as a sandwiching region forming member that forms the nip portion N10. The roll member 240 is made of, for example, metal and has a cored bar part 244 having a cylindrical shape and an elastic body layer 246 that covers the cored bar part 244. As a material of the elastic body layer 246, for example, rubber having heat resistance can be used. In order to suppress the adhesion of toner to the surface of the elastic layer 246, it is desirable to form a release layer made of, for example, a resin on the surface of the elastic layer 246.

  As described above, the roll member 240 has the elastic body layer 246. For this reason, the roll member 240 is elastically deformed so that the contact surface 242 contracts, for example, when the contact surface 242 is pressed from the outside. Further, the roll member 240 has a contact surface 242 having a higher hardness than a pressure pad 260 described later, and a contact surface 242 having a hardness lower than that of a pressure member 270 described later. The hardness of the roll member 240, the hardness of the pressure pad 260, and the hardness of the pressure member 270 can be measured using, for example, a durometer (not shown), and can be defined based on, for example, JIS K6301.

  A heat source 248 that can use, for example, a halogen lamp is disposed in the hollow portion of the roll member 240. Further, a drive source (not shown) such as a motor is connected to the roll member 240, and the roll member 240 is driven to rotate in the direction of arrow b shown in FIG. 3 upon receiving drive transmission from the drive source. To do.

  The fixing device 200 further includes a pressure pad 260. The pressure pad 260 is in contact with the inner peripheral surface 214 of the belt member 210, and presses the belt member 210 against the contact surface 242 of the roll member 240, thereby forming a first curve N12 in the nip portion N10. . As described above, since the hardness of the contact surface 242 of the roll member 240 is higher than the hardness of the pressure pad 260, when the pressure pad 260 is pressed against the contact surface 242 via the belt member 210, the pressure pad 260 deforms following the contact surface 242. Then, the pressure pad 260 becomes the contact surface 242 and is bent, whereby the belt member 210 is bent and the nip portion N10 is bent to form the first curve N12.

  As a material of the pressure pad 260, for example, various rubbers can be used. The pressure pad 260 is used as an urging means, and is connected to one end of an elastic body 262 that can use, for example, a coil spring, and the other end of the elastic body 262 is pressed later. It is connected to the portion 280. The pressure pad 260 is urged toward the inner peripheral surface 214 side of the belt member 210 by the elastic body 262.

  The first curve N12 generated by the action of the pressure pad 260 is a direction in which the lower part in the direction of gravity is convex as shown in FIG.

  The pressure pad 260 is arranged on the upstream side of a pressure member 270 described later in the conveyance direction of the paper P. Further, the pressure pad 260 is longer than the pressure member 270 in contact with the inner peripheral surface 214 in the conveyance direction of the paper P.

  The fixing device 200 further includes a pressure member 270. The pressure member 270 is in contact with the inner peripheral surface 214 of the belt member 210 and is disposed at a position different from the pressure pad 260 in the transport direction of the paper P, and the belt member 210 is placed on the contact surface of the roll member 240. By pressing against the 242, the second curve N <b> 24 is formed in the nip portion N <b> 10.

  As a material of the pressing member 270, for example, a metal can be used. As described above, since the hardness of the contact surface 242 of the roll member 240 is lower than that of the pressure member 270, when the pressure member 270 is pressed against the contact surface 242 via the belt member 210, The roll member 240 is deformed so that the belt member 210 enters the contact surface 242 side, and the nip portion N10 is curved to form a second curve N14.

  As shown in FIG. 3, the direction of the curve N12 is such that the lower side in the direction of gravity is convex. As described above, the direction of the second curve N14 of the nip portion N10 caused by the action of the pressure member 270 is opposite to the direction of the first curve N12 of the nip part N10 caused by the action of the pressure pad 260. ing.

  The fixing device 200 further includes a pressing unit 280. The pressing unit 280 supports the pressure pad 260 and the pressure member 270 and presses the pressure pad 260 and the pressure member 270 together against the inner peripheral surface 214 of the belt member 210. The aforementioned elastic body 262 is attached to the pressing portion 280.

  The fixing device 200 configured as described above fixes the toner image I to the paper P passing through the nip portion N10 using heat and pressure. Further, in the fixing device 200 configured as described above, when a sheet P such as a thick sheet passes through the curve N12 of the nip portion N10, the sheet P may be bent in a direction that protrudes downward. . Further, in the fixing device 200 configured as described above, when the paper P such as plain paper passes through the curve N14 of the nip portion N10, the paper P may be bent in an upward convex direction.

  The curvature correcting device 400 includes a belt member 410. The belt member 410 is a sheet P on which the toner image I is fixed by the fixing device 200 and is used as a conveying member that conveys the sheet P in contact with the outer peripheral surface 412, and is belt-shaped and endless. Further, the belt member 410 moves so as to rotate in the direction of the arrow d shown in FIG. 3 by a configuration such as following a roll member 440 described later. As a material of the belt member 410, for example, a flexible resin or the like can be used.

  The straightening device 400 further includes a roll member 440. The roll member 440 is a curved surface, has a contact surface 442 that is a surface that contacts the outer peripheral surface 412 of the belt member 410, and corresponds to a sandwiching region in which a sheet is sandwiched between the contact surface 442 and the belt member 410. It is used as a sandwiching region forming member that forms the nip portion N20. The roll member 440 is made of, for example, metal and has a cored bar part 444 having a cylindrical shape and an elastic body layer 446 that covers the cored bar part 444. As a material of the elastic body layer 446, for example, rubber having heat resistance can be used. Further, in order to suppress adhesion of toner to the surface of the elastic layer 446, it is desirable to form a release layer made of, for example, a resin on the surface of the elastic layer 446.

  As described above, the roll member 440 has the elastic body layer 446. For this reason, the roll member 440 is elastically deformed so that the contact surface 442 contracts, for example, when the contact surface 442 is pressed from the outside. Further, the roll member 440 has a contact surface 442 having a hardness higher than that of a pressure pad 460 described later, and a contact surface 442 having a hardness lower than that of a pressure member 470 described later. The hardness of the roll member 440, the hardness of the pressure pad 460, and the hardness of the pressure member 470 can be measured using, for example, a durometer (not shown), and can be defined based on, for example, JIS K6301.

  A driving source (not shown) such as a motor is connected to the roll member 440, and the roll member 440 is driven to rotate in the direction of arrow e shown in FIG.

  The curvature correcting device 400 further includes a pressure pad 460. The pressure pad 460 is in contact with the inner peripheral surface 414 of the belt member 410 and presses the belt member 410 against the contact surface 442 of the roll member 440, thereby forming the first curve N22 in the nip portion N20. Used as the first curve forming member. As described above, since the hardness of the contact surface 442 of the roll member 440 is higher than the hardness of the pressure pad 460, when the pressure pad 460 is pressed against the contact surface 442 via the belt member 410, the pressure pad 460 deforms following the contact surface 442. Then, the pressure pad 460 is curved following the contact surface 442, so that the belt member 410 is curved, and the nip portion N20 is curved to form the first curve N22.

  As a material of the pressure pad 460, for example, various rubbers can be used. The pressure pad 460 is used as an urging means and is connected to one end of an elastic body 462 that can use, for example, a coil spring, and the other end of the elastic body 462 is pressed later. It is connected to the part 480. The pressure pad 460 is urged toward the inner peripheral surface 414 side of the belt member 410 by the elastic body 462.

  The first curve N22 generated by the action of the pressure pad 460 is a direction in which the upper part in the direction of gravity is convex as shown in FIG.

  The pressure pad 460 is disposed on the upstream side of a pressure member 470 described later in the conveyance direction of the paper P. In addition, the pressure pad 460 is longer in contact with the inner peripheral surface 414 in the conveyance direction of the paper P than a pressure member 470 described later.

  The curvature correcting device 400 further includes a pressing member 470. The pressure member 470 is in contact with the inner peripheral surface 414 of the belt member 410 and is disposed at a position different from the pressure pad 460 in the transport direction that is the direction in which the paper P is transported. By being pressed against the contact surface 442 of the roll member 440, it is used as a second curve forming member that forms a second curve N24 in the nip portion N20.

  As a material of the pressure member 470, for example, a metal can be used. As described above, since the hardness of the contact surface 442 of the roll member 440 is lower than the hardness of the pressure member 470, when the pressure member 470 is pressed against the contact surface 442, the pressure member 470 and the belt member 410 are moved. The roll member 440 is deformed so as to enter the contact surface 442 side, and the nip portion N20 is curved to form a second curve N24.

  As shown in FIG. 3, the direction of the second curve N24 is a direction that protrudes downward in the direction of gravity. As described above, the direction of the second curve N24 of the nip portion N20 caused by the action of the pressure member 470 is opposite to the direction of the first curve N22 of the nip part N20 caused by the action of the pressure pad 460. ing.

  The curvature correcting device 400 further includes a pressing unit 480. The pressing unit 480 supports the pressure pad 460 and the pressure member 470 and presses the pressure pad 460 and the pressure member 470 together against the inner peripheral surface 414 of the belt member 410. The pressing portion 480 has a mounting plate 482 to which the elastic body 462 is mounted and the pressing member 470 is mounted.

  The straightening device 400 further includes a cooling device 490 for cooling the paper P heated by the fixing device 200. The cooling device 490 is a so-called heat sink, and includes a plurality of diffusion plates 492 that dissipate heat. In the cooling device 490, heat is transferred from the paper P to the diffusion plate 492 via the belt member 410, the pressure pad 460, the elastic body 462, the pressure member 470, the mounting plate 482, etc., and the heat transferred from the paper. Is diffused by the diffuser plate 492.

  The cooling device 490 is configured integrally with the pressing unit 480. More specifically, the cooling device 490 and the pressing unit 480 are integrated so that the diffusion plate 492 included in the cooling device 490 is mounted on the mounting plate 482 included in the pressing unit 480.

  In the curving straightening device 400 configured as described above, the curving of the paper P, such as thick paper, that is curved so that the lower side is convex when the toner image I is fixed by the fixing device 200 is generated in the nip portion N20. It is corrected by passing through the first curved line N22 that is convex upward. Further, in the curving straightening device 400 configured as described above, the curving of the paper P such as plain paper that is curved so that the upper side is convex when the toner image I is fixed by the fixing device 200 is caused by the nip. It is corrected by passing through the second curved line N24 that is convex downward formed in the part N20.

  In the image forming apparatus 10, as described above, the roll member 240 is used as a heating member that heats the paper, and the belt member 210 is used as a pressure member that presses the paper against the roll member 240. The portion N10 is used as a sandwiching region, the belt member 210 and the roll member 240 are used as two fixing members, and the nip portion N10 is formed by the two fixing members coming into contact with each other. The sheet P is used as a fixing sandwiching area for fixing the toner image I on the sandwiched sheet P.

  Further, in the image forming apparatus 10, as described above, the belt member 410 is used as a conveying member, the roll member 440 is used as a sandwiching region forming member, and the nip portion N20 is used as a sandwiching region. In addition, the belt member 410 and the roll member 440 are used as two straightening members that are in contact with each other, and the nip portion N20 is a sandwiching region for straightening formed by the two straightening members coming into contact with each other. It is used. Then, as described above, the image forming apparatus 10 allows the sheet P on which the toner image I is fixed by the fixing device 200 to pass through the nip portion N20, thereby causing the sheet P to bend when passing through the nip portion N10. To correct.

  The nip portion N20 has a shape symmetrical to the nip portion N10 with respect to the conveyance portion 702 used for conveying the paper P from the fixing device 200 to the curvature correcting device 400 in the conveyance path 700. Therefore, when the sheet P passes through the nip portion N20, a force opposite to the force applied to the sheet P when passing through the nip portion N10 is applied to the sheet P, and the shape of the nip portion N20 However, as compared with a device that is not symmetrical with the nip portion N10 with respect to the conveyance portion 702, the curvature of the sheet P is corrected more favorably.

  FIG. 4 shows a fixing device 200 and a curvature correcting device 400 included in the image forming apparatus 10 according to the second embodiment of the present invention. The configuration of the fixing device 200 in the second embodiment is the same as the configuration of the fixing device 200 in the first embodiment described above, although there are differences in the shape of the members. For this reason, the same reference numerals (see FIG. 3) as the reference numerals attached to the fixing device 200 in the first embodiment are attached to FIG. 4, and the description of the fixing device 200 in the second embodiment is omitted.

  The curving straightening device 400 in the second embodiment does not have the cooling device 490 (see FIG. 3) that the curving straightening device 400 according to the first embodiment described above has, but this second implementation. A cooling device 490 may be provided in the form.

  Further, the curvature correcting device 400 according to the second embodiment includes a position changing mechanism 500 that is a configuration that the curvature correcting device 400 according to the first embodiment does not have. The position changing mechanism 500 is used as changing means for changing the position of the pressure member 470 as the second curve forming member with respect to the roll member 440 as the sandwiching region forming member.

  As shown in FIG. 4, the position changing mechanism 500 is connected to a bearing 420 that rotatably supports the roll member 440, and transmits driving from a driving source (not shown) such as a motor to the bearing 420. Then, the bearing 420 and the roll member 440 are moved together to move closer to the pressure member 470, and the bearing 420 and the roll member 440 are moved together to move away from the pressure member 470. An arrow f in FIG. 4 indicates the moving direction of the roll member 440 and the bearing 420 by the position changing mechanism 500.

  Instead of configuring the position changing mechanism 500 to move the roll member 440 with respect to the pressure member 470 fixed as described above, the pressure member 470 with respect to the fixed roll member 440. You may comprise so that it may move. Moreover, you may comprise so that both the pressurization member 470 and the roll member 440 may be moved.

  The configuration of the image forming apparatus 10 according to the second embodiment is the same as that of the image forming apparatus 10 according to the first embodiment, except for the part that has described the difference from the image forming apparatus 10 according to the first embodiment. It is. Therefore, the same reference numerals as those assigned to the image forming apparatus 10 according to the first embodiment are attached to FIG. 4, and the description of the same parts as those of the image forming apparatus 10 according to the first embodiment is omitted. .

  FIG. 5 illustrates the operation of the curving straightening device 400 according to the second embodiment. More specifically, the change of the position of the pressing member 470 relative to the roll member 440 by the position changing mechanism 500 is described. ing. Hereinafter, the position of the pressure member 470 with respect to the roll member 440 shown in FIG. 5A is a first position, and the position of the pressure member 470 with respect to the roll member 440 shown in FIG. 5B is a second position. .

  As shown in FIG. 5A, when the pressure member 470 is in the first position with respect to the roll member 440, both the first curve N22 and the second curve N24 are formed in the nip portion N20. The When the roll member 440 is moved away from the pressure member 470 using the position changing mechanism 500 from the state shown in FIG. 5A, the curvature correcting device 400 is in the state shown in FIG.

  As shown in FIG. 5B, when the pressure member 470 is in the second position with respect to the roll member 440, the first curve N22 is formed in the nip portion N20, but the curve N24 is formed in the nip portion N20. Is not formed. When the roll member 440 is moved closer to the pressing member 470 using the position changing mechanism 500 from the state shown in FIG. 5B, the curvature correcting device 400 is in the state shown in FIG.

  Further, when the roll member 440 is moved further away from the pressure member 470 using the position changing mechanism 500 from the state shown in FIG. 5B, the roll member 440 and the belt member 410 are separated from each other, and the nip portion N20 is not formed (not shown). Hereinafter, the position of the pressure member 470 with respect to the roll member 440 in which the nip portion N20 is not formed is defined as a third position.

  FIG. 6 illustrates a control unit 900 included in the image forming apparatus 10 according to the second embodiment. As illustrated in FIG. 6, the control unit 900 includes a control circuit 902 including, for example, a CPU, and image data is input to the control circuit 902 via the communication interface 904. An output from the operation panel 800 is input to the control circuit 902, and the image forming unit 100, the paper feeding device 600, the paper feeding device 620, and the position changing mechanism 500 are controlled by the output from the control circuit 902. Is done.

  FIG. 7 is a flowchart showing the control of the curvature correcting device 400 by the control unit 900. When a series of controls are started as shown in FIG. 7, in step S10, the control circuit 902 transfers and transfers a sheet on which an image is formed, that is, a toner image, based on an input from the operation panel 800. It is determined whether the paper on which the toner image is fixed is plain paper.

  When it is determined in step S10 that the paper on which an image is to be formed is plain paper, in step S20, the control circuit 902 controls the position changing mechanism 500 so that the position of the pressure member 470 with respect to the roll member 440 is the first. The roll member 440 is moved to the position changing mechanism 500 so as to be in the position 1 (see FIG. 5A).

  If it is determined in step S10 that the paper on which the image is to be formed is not plain paper, in step S30, the control circuit 902, based on the input from the operation panel 800, the paper on which the image is formed, that is, the toner image. Is transferred, and it is determined whether or not the sheet on which the transferred toner image is fixed is a thick sheet.

  When it is determined in step S30 that the sheet on which the image is to be formed is a thick sheet, in step S40, the control circuit 902 controls the position changing mechanism 500 so that the position of the pressure member 470 with respect to the roll member 440 is the second. The roll member 440 is moved to the position changing mechanism 500 so that the roll member 440 and the belt member 410 are separated from each other (see FIG. 5B).

  In step S50, which is the next step, for example, based on image data input via the communication interface 904, it is determined that the sheet on which the image is formed is the last sheet in the process for forming a series of images. In step S60, the control circuit 902 controls the position changing mechanism 500 so that the position of the pressure member 470 with respect to the roll member 440 becomes the third position (see FIG. 5B). After moving the roll member 440 to the mechanism 500, a series of control is terminated.

  FIG. 8 shows a fixing device 200 and a curvature correcting device 400 included in the image forming apparatus 10 according to the third exemplary embodiment of the present invention. The fixing device 200 in the second embodiment described above has an elastic body 262 (see FIG. 4). On the other hand, the fixing device 200 according to the third embodiment does not have the elastic body 262, and the pressure pad 260 is directly attached to the pressing portion 280. In the second embodiment described above, the pressing portion 280 and the pressing member 270, which are separate members, are a single member in the third embodiment.

  Further, the curvature correcting device 400 in the second embodiment described above has an elastic body 462 (see FIG. 4). On the other hand, the curvature correcting device 400 in the third embodiment does not have the elastic body 462, and the pressing pad 460 is directly attached to the pressing portion 480. In the second embodiment described above, the pressing portion 480 and the pressure member 470, which are separate members, are a single member in the third embodiment.

  The configuration of the image forming apparatus 10 according to the third embodiment is the same as that of the image forming apparatus 10 according to the second embodiment, except for the parts described above that are different from the image forming apparatus 10 according to the second embodiment. It is. For this reason, the description of the same part as the image forming apparatus 10 according to the first embodiment is omitted.

  FIG. 9 illustrates the operation of the bend correction device 400 according to the third embodiment. More specifically, the position of the pressure member 470 relative to the roll member 440 by the position changing mechanism 500 in the bend correction device 400 is described. The change is explained. Similar to the second embodiment described above, in this third embodiment as well, the pressure member 270 includes the first bending N22 and the first bending N22 in the nip portion N20 shown in FIG. Although the first curve N22 is formed at the first position with respect to the roll member 440 where both the second curve N24 and the second curve N24 are formed, and the nip part N20 shown in FIG. 9B, the curve N24 is formed at the nip part N20. The second position with respect to the roll member 440 that is not formed can be taken.

  Similar to the second embodiment described above, also in this third embodiment, the pressure member 270 is a roll member in which the roll member 440 and the belt member 410 are separated from each other and the nip portion N20 is not formed. A third position relative to 440 can be taken. Moreover, the curvature correction apparatus 400 in this 2nd Embodiment is controlled similarly to control of the curvature correction apparatus 400 in the above-mentioned 3rd Embodiment demonstrated with reference to FIG.

  As described above, the present invention can be applied to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and a curvature correcting apparatus used in these image forming apparatuses, for example.

DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus 200 ... Fixing device 400 ... Curvature straightening device 410 ... Belt member 412 ... Outer peripheral surface 414 ... Inner peripheral surface 440 ... Roll member 442 ... Curved surface 460 ... Pressure pad 462 ... Elastic body 470 ... Pressure member 480 ... Pressing part 490 ... Cooling device 500 ... Position changing mechanism N20 ... Nip part N22 ... No. 1 curve N24 ... 2nd curve

Claims (7)

A fixing device for fixing a toner image on a recording medium;
A conveying member that conveys a recording medium having a toner image fixed thereon by the fixing device and that is in contact with an outer peripheral surface, the conveying member being band-shaped and endless;
A sandwiching area forming member that has a contact surface in contact with the outer peripheral surface and forms a sandwiching area in which a recording medium is sandwiched between the contact surface and the transport member;
A first curve forming member that is in contact with the inner peripheral surface of the transport member and that forms the first curve in the sandwiched region by pressing the transport member against the contact surface;
It is in contact with the inner peripheral surface of the transport member and is disposed at a position different from the first curve forming member in the transport direction, which is the direction in which the recording medium is transported, and the transport member is placed on the contact surface. A second curve forming member that forms a second curve in the sandwiching region by pressing against the second curve forming member;
Have
The image forming apparatus wherein the first curve and the second curve are opposite to each other. Position change means for changing the position of the second curve forming member with respect to the sandwiching region forming member,
The position changing means is at least
A position at which the first curve and the second curve are formed;
A position where the first curve is formed and the second curve is not formed;
The image forming apparatus according to claim 1, wherein the position of the second curve forming member with respect to the sandwiching region forming member is changed between the two. The sandwich region forming member is
Elastically deformable,
The image forming apparatus according to claim 1, wherein the hardness is higher than that of the first curve forming member and lower than that of the second curve forming member. The first curve forming member is:
It is arranged on the upstream side of the second curve forming member in the transport direction,
4. The image forming apparatus according to claim 1, wherein a length in contact with the inner peripheral surface in the transport direction is longer than that of the second curve forming member. The fixing device fixes the toner image on the recording medium using at least heat;
The image forming apparatus according to claim 1, further comprising a cooling device that cools the recording medium. A recording medium in which a first curve and a second curve, which are opposite to each other, are formed by the two fixing members coming into contact with each other, and are moving in a fixing sandwiching area that is a sandwiching area of the recording medium A fixing device for fixing the toner image to the toner,
The recording medium formed by the two correction members coming into contact with each other and passing the recording medium on which the toner image is fixed by the fixing device is passed through the correction clamping area, which is the area where the recording medium is sandwiched. A curvature correction device for correcting curvature;
A conveyance path used for conveying a recording medium from the fixing device to the curvature correcting device;
Have
The correction sandwiching area is an image forming apparatus having a symmetrical shape with respect to the fixing sandwiching area and the conveyance path. A conveying member that conveys a recording medium having a toner image fixed thereon by a fixing device and that is in contact with the outer peripheral surface, the belt-shaped and endless conveying member;
A sandwiching area forming member that has a contact surface in contact with the outer peripheral surface and forms a sandwiching area in which a recording medium is sandwiched between the contact surface and the transport member;
A first curve forming member that is in contact with the inner peripheral surface of the transport member and that forms the first curve in the sandwiched region by pressing the transport member against the contact surface;
It is in contact with the inner peripheral surface of the transport member and is disposed at a position different from the first curve forming member in the transport direction, which is the direction in which the recording medium is transported, and the transport member is placed on the contact surface. A second curve forming member that forms a second curve in the sandwiching region by pressing against the second curve forming member;
Have
The curvature correction device in which the first curvature and the second curvature are opposite to each other.

Images