JP5928067B2 - Fixing unit and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing unit and an image forming apparatus.

As a conventional technique, for example, there is known an image forming apparatus in which a fixing device and a corrugation roller are arranged in a state where a paper feeding direction of a fixing device and a paper feeding direction of a corrugation roller are different from each other (Patent Document). 1).
Further, as a conventional technique, for example, a fixing device that fixes an unfixed image in a fixing region formed between a heat fixing member and a pressure fixing member, and elastically deforms the heat fixing member in the fixing region. Is known (Patent Document 2).

JP 2007-230746 A JP 2010-2773 A

  An object of the present invention is to suppress the occurrence of wrinkles in a recording material that is subjected to a fixing process while being deformed and then conveyed along a curved conveyance path.

According to a first aspect of the present invention, the fixing member is rotatably provided, extends from one end to the other end along the rotation axis, and elastically deforms, and the fixing nip is pressed between the fixing member and the fixing member. part to form, shape along the rotation axis direction of the fixing member in the fixing nip portion is concave in the fixing member is elastically deformed so as to project, by passing the recording material to the fixing nip portion, a pressure member for fixing a toner image while deforming the recording material so that the central portion of the rotational axis direction has a convex shape in one side of the recording material on the recording material, the toner image at the fixing nip portion Is provided on the downstream side in the transport direction from the curved portion in the transport path, and a transport path for transporting the recording material to which the one surface side is curved to be inside. Transported And a conveying means for transporting the recording material after wearing, said conveying means includes a first conveying shaft opposite to the one surface of the recording material conveyed extends along the rotation axis direction, the rotation A second transport shaft that faces the other surface of the recording material that extends along the axial direction and faces the first transport shaft across the recording material, the first transport shaft and the first transport shaft The two transport shafts have a curved shape so that a central portion in the rotation axis direction protrudes from the first transport shaft toward the second transport shaft, and the first transport shaft and the second transport shaft A fixing unit that transports the recording material while deforming the recording material so that the central portion in the rotation axis direction on the one surface of the recording material is concave by passing the recording material between It is.
According to a second aspect of the present invention, the fixing member is opposed to the one surface of the recording material on which the unfixed toner image is formed on the one surface on the upstream side of the curved portion in the conveyance path. And the pressure member elastically deforms the fixing member by pressing the fixing member so that the shape of the fixing member along the rotation axis direction is concave, and the recording material the central portion of the rotational axis direction of the one surface is a fixing unit according to claim 1, wherein the deforming the recording material so as to be convex.
According to a third aspect of the present invention, the conveying means includes a concave portion and a convex portion alternately arranged along the rotation axis direction on the one surface of the recording material after fixing, and a central portion in the rotation axis direction is 3. The fixing unit according to claim 1, wherein the recording material is deformed so as to be concave, and the deformed recording material is discharged toward the outside.
Fourth aspect of the present invention, the first conveying axis of the conveying means has a plurality of first roll member that is separated into the rotation axis direction, the second transport axis, the separation to the rotation axis direction A plurality of second roll members, the first roll member in contact with the one surface of the recording material, and the second roll member in contact with the other surface of the recording material, in the one surface of the recording material, so that the central portion of the along the rotation axis direction and a concave and convex alternately arranged and the rotation axis direction is concave, and wherein the deforming the recording material The fixing unit according to claim 3.

According to a fifth aspect of the present invention, there is provided a toner image forming means for forming a toner image, a transfer means for transferring the toner image formed by the toner image forming means onto a recording material, and the transfer means transferring the toner image onto the recording material. A fixing unit that fixes the toner image to the recording material, the fixing unit being rotatably provided, extending from one end to the other along the rotation axis, and elastically deforming a fixing member; The fixing member is pressed to form a fixing nip portion with the fixing member, and the fixing member is elastically formed so that the shape along the rotation axis direction of the fixing member is concave or convex in the fixing nip portion. deforming, by passing the recording material to the fixing nip portion, while deforming the recording material so that the central portion of the rotational axis direction has a convex shape in one side of the recording material the toner image on the recording medium Fixed A pressure member, a conveyance path for conveying the recording material on which the toner image is fixed at the fixing nip portion, through a curved portion curved so that the one surface side is inside, A conveying unit that is further provided downstream of the curved portion in the conveying direction and conveys the recording material that has been fixed and conveyed. The conveying unit of the fixing unit extends along the rotation axis direction. The first conveying shaft facing the one surface of the recording material to be conveyed, and the other surface of the recording material conveyed along the rotation axis direction are opposed to the first surface with the recording material interposed therebetween. A second transport shaft facing the transport shaft, and the first transport shaft and the second transport shaft project in the direction from the first transport shaft toward the second transport shaft at the center in the rotation axis direction. Having a curved shape, the first By transporting the recording material between the feeding shaft and the second transport shaft, the recording material is transported while being deformed so that the central portion in the rotation axis direction on the one surface of the recording material is concave. The image forming apparatus is characterized by the above.

According to the first aspect of the present invention, it is possible to suppress the occurrence of wrinkles in the recording material that is conveyed along the curved conveyance path after being subjected to the fixing process while being deformed.
According to the second aspect of the present invention, the fixing performance of the toner image on the recording material can be improved as compared with the case where this configuration is not adopted.
According to the third aspect of the present invention, it is possible to discharge the recording material to a position away from the conveying means, and the stackability of the discharged recording material can be improved as compared with the case where this configuration is not adopted. it can.
According to the fourth aspect of the present invention, as compared with the case where the present configuration is not adopted, it is possible to form the unevenness on the recording material with a simple configuration.
According to the fifth aspect of the present invention, it is possible to suppress the occurrence of wrinkles in the recording material that is conveyed along the curved conveyance path after being subjected to the fixing process while being deformed.

1 is a diagram illustrating a configuration example of an image forming apparatus to which a fixing device according to an exemplary embodiment is applied. FIG. 3 is a perspective view of a fixing unit of the present embodiment. It is III-III sectional drawing of FIG. It is a figure for demonstrating the shape of the fixing roll of this Embodiment, a pressure belt, and a press pad. It is a figure for demonstrating the structure of the discharge apparatus of this Embodiment.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a diagram illustrating a configuration example of an image forming apparatus 1 to which the fixing device 20 of the present embodiment is applied. An image forming apparatus 1 shown in FIG. 1 includes an image forming unit 100 that forms an image on a sheet P as an example of a recording material based on image data, a control unit 300 that controls the operation of the entire image forming apparatus 1, and an image forming unit. A paper supply unit 30 that supplies the paper P to the unit 100, a paper reversing mechanism 50 that reverses the front and back of the paper P on which the image is formed by the image forming unit 100, and supplies the paper P to the image forming unit 100 again A paper stacking unit YS for stacking paper P on which an image is formed is provided. Further, the image forming apparatus 1 includes a toner cartridge 60 that supplies toner to the image forming unit 100. Further, the image forming apparatus 1 performs communication with a personal computer (PC) or the like, for example, a receiving unit 200 that receives image data, and an image that performs predetermined image processing on the image data received by the receiving unit 200. The processing unit 400 includes a user interface (UI) 500 that receives instructions from the user and displays messages and the like to the user.

  Further, the image forming apparatus 1 according to the present embodiment is provided with a paper transport path YR through which paper is transported from the paper supply unit 30 to the paper stacking unit YS via the transfer unit Tp and the fixing device 20. . Further, the sheet P is connected to the sheet conveyance path YR on the downstream side of the fixing device 20 and joined to the sheet conveyance path YR on the upstream side of the transfer unit Tp. A reversing transport path SR for transporting to the forming unit 100 is provided.

  The image forming unit 100 according to the present embodiment includes a photosensitive layer on the surface, forms a latent electrostatic image and holds a toner image, and a charging device 12 that charges the photosensitive drum at a predetermined potential. , An exposure device 13 for exposing the photosensitive drum 11 charged by the charging device 12 based on image data, a developing device 14 for developing the electrostatic latent image formed on the photosensitive drum 11, and the photosensitive drum 11 after transfer. A cleaning device 16 is provided for cleaning the surface.

  Further, the image forming unit 100 forms a transfer unit Tp between the image forming unit 100 and the transfer unit as an example of a transfer unit that transfers the toner image formed on the photoconductive drum 11 onto the paper P. 15 and a fixing unit 80 as an example of a fixing unit that fixes the toner image transferred onto the paper P onto the paper P and discharges the paper P on which the toner image is fixed to the paper stacking unit YS. The fixing unit 80 is detachably attached to the apparatus main body of the image forming apparatus 1. The fixing unit 80 according to the present embodiment includes a fixing device 20 that fixes the toner image transferred onto the paper P by the transfer device 15 on the paper P, and a paper P on which the fixing process has been performed by the fixing device 20. And a discharge device 70 as an example of a transport unit that discharges toward the portion YS. The configuration of the fixing unit 80 will be described in detail later.

Further, the image forming unit 100 is provided with a registration roll (registration roll) 47 and a transport roll 51.
The registration roll 47 temporarily stops the conveyance of the sheet P in a state where the rotation is stopped, and rotates the sheet P at a predetermined timing, thereby supplying the sheet P while performing registration adjustment on the transfer portion Tp. .
The transport roll 51 transports the paper P whose front and back are reversed by the paper reversing mechanism 50 toward the registration roll 47 again.

  The paper supply unit 30 of this embodiment includes a paper storage unit 31, a pulling roll 33, and a winding mechanism 35. The paper storage unit 31 has, for example, a rectangular parallelepiped shape having an opening in the upper portion, and stores a plurality of papers P therein. The pull-in roll 33 sends out the upper sheet P of the plurality of sheets P stored in the sheet storage unit 31 toward the winding mechanism 35. The webbing mechanism 35 webs the paper P sent out by the pull-in roll 33 one by one and sends it out to the registration roll 47.

Next, an image forming process performed in the image forming apparatus 1 according to the present embodiment will be described.
First, image data formed by a PC or the like is received by the receiving unit 200, and the image data is output from the receiving unit 200 to the image processing unit 400. The image data output to the image processing unit 400 is subjected to image processing by the image processing unit 400 and output to the exposure apparatus 13. The exposure device 13 that has acquired the image data selectively exposes the photosensitive drum 11 charged by the charging device 12 based on the acquired image data to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 11 is developed by the developing device 14 as, for example, a black (K) toner image.

  On the other hand, in the paper supply unit 30, the drawing roll 33 rotates in synchronization with the image formation timing, and the paper P is supplied from the paper storage unit 31. Then, the sheets P that are rolled up one by one by the winding mechanism 35 are conveyed to the registration roll 47 and are temporarily stopped. Thereafter, the registration roll 47 rotates in accordance with the rotation timing of the photosensitive drum 11, and the paper P is supplied to the transfer portion Tp. Then, the toner image formed on the photosensitive drum 11 is transferred onto the paper P in the transfer portion Tp.

Thereafter, the sheet P on which the toner image has been transferred is subjected to a fixing process by the fixing device 20 in the fixing unit 80 and then discharged to the sheet stacking unit YS by the discharging device 70. When an image is formed not only on the first side of the paper P but also on the second side (images are formed on both sides of the paper P), the paper P that has passed through the fixing device 20 is fed by the paper reversing mechanism 50. After the front and back sides are reversed, the sheet is supplied again to the transfer portion Tp. Then, the toner image formed on the photosensitive drum 11 is transferred to the second surface of the paper P at the transfer portion Tp. Thereafter, the sheet P on which the toner image is transferred to the second surface is subjected to a fixing process by the fixing device 20 in the fixing unit 80 and then discharged to the sheet stacking unit YS by the discharging device 70.
In this way, the image forming process in the image forming apparatus 1 is repeatedly executed for the number of printed sheets.

Next, the fixing unit 80 of the present embodiment will be described.
FIG. 2 is a perspective view of the fixing unit 80 of the present embodiment. 3 is a cross-sectional view taken along the line III-III in FIG.
As shown in FIGS. 2 and 3, the fixing unit 80 of this embodiment includes a housing 81. In the housing 81, as shown in FIG. 3, a fixing device 20 and a discharge device 70 are provided. In the housing 81, a paper transport path YR through which the paper P is transported from the fixing device 20 toward the discharge device 70 is provided. As shown in FIGS. 2 and 3, the discharge device 70 of the present embodiment is partially exposed to the outside of the housing 81.

Next, the configuration of the fixing device 20 provided in the fixing unit 80 will be described.
As shown in FIG. 3, the fixing device 20 according to the present embodiment is arranged in contact with the fixing roll 21 as an example of a fixing member and the outer peripheral surface of the fixing roll 21 and between the fixing roll 21 and the nip. And a pressure belt 22 forming the portion N.
Further, the fixing device 20 includes a pressing pad 23 that presses the fixing roll 21 via the pressure belt 22. In the present embodiment, a pressure member is constituted by the pressure belt 22 and the pressure pad 23.

  The fixing roll 21 has a cylindrical shape as a prototype. For example, the outer peripheral surface of the prototype (cylindrical shape) has a diameter of 30 mm and a thickness of 0.1 mm. The fixing roll 21 is made of, for example, nickel steel, is elastically deformable, and is configured to hold a cylindrical shape by its own rigidity.

The material constituting the fixing roll 21 and the dimensions of the fixing roll 21 are not limited to those described above. As a material constituting the fixing roll 21, for example, stainless steel, nickel-cobalt alloy, copper, gold, nickel-iron alloy, and the like can be used in addition to nickel steel. Further, the thickness of the fixing roll 21 may be any thickness as long as the fixing roll 21 can be elastically deformed and can retain the cylindrical shape by rigidity, and is preferably 0.07 mm to 0.12 mm, for example.
In addition, in order to improve the peeling performance of the paper P from the fixing roll 21, a surface layer made of a fluororesin or the like having good releasability may be further provided on the outer peripheral surface of the fixing roll 21.

A heater 21 a is provided inside the fixing roll 21. For example, a 570 W halogen lamp can be used as the heater 21a.
As shown in FIG. 3, the heater 21a is arranged in a state of being separated from the fixing roll 21, and the inner peripheral surface of the fixing roll 21 and the heater 21a are not in contact with each other. In the present embodiment, a support member or the like for maintaining the shape of the fixing roll 21 as in the related art is not provided on the inner peripheral surface of the fixing roll 21. Therefore, the fixing roll 21 and the heater 21a are disposed so as to face each other directly, and the fixing roll 21 can be directly heated by the heater 21a.

The pressurizing belt 22 is formed of an endless belt member whose prototype is, for example, a cylindrical shape. The pressure belt 22 of the present embodiment is formed, for example, to have a diameter of 30 mm and a width of 370 mm at the time of a prototype (cylindrical shape). In the following description, the width direction of the pressure belt 22 (that is, the direction perpendicular to the paper surface in FIG. 3) may be simply referred to as “width direction”.
The pressure belt 22 is, in order from the inner peripheral surface side, a base layer made of a sheet-like member having high heat resistance, an elastic layer laminated on the base layer, and an outer circumference of the pressure belt 22 laminated on the elastic layer. A surface release layer exposed on the surface is laminated.

As the base layer, a flexible material having excellent mechanical strength and heat resistance is used. Examples of the material constituting the base layer include fluorine resin, polyimide resin, polyamide resin, polyamideimide resin, PEEK (polyetheretherketone) resin, PES (polyethersulfone) resin, PPS (polyphenylene sulfide) resin, and PFA resin. PTFE (polytetrafluoroethylene) resin, FEP (tetrafluoroethylene hexafluoropropylene copolymer) resin, and the like. The thickness of the base layer is preferably, for example, 10 to 150 μm, and more preferably 30 to 100 μm.
As the elastic layer, silicone rubber, fluorine rubber, fluorosilicone rubber or the like having excellent heat resistance and thermal conductivity is used. 10-500 micrometers is preferable and, as for thickness, 50-300 micrometers is more preferable.
As the surface release layer, for example, PFA resin, PTFE resin, fluororesin, silicone resin, fluorosilicone rubber, silicone rubber or the like is used.

As shown in FIG. 3, the pressing pad 23 is provided along the width direction of the pressure belt 22 on the inner periphery of the pressure belt 22. The pressing pad 23 presses the fixing roll 21 via the pressure belt 22, and forms a nip portion N between the pressing pad 23 and the fixing roll 21.
Examples of the material constituting the pressing pad 23 include elastic bodies such as silicone rubber and fluorine rubber, and heat resistant resins such as LCP (Liquid Crystal Polymer) and PPS (polyphenylene sulfide).

  In addition, in order to improve the slidability between the pressure pad 23 and the pressure belt 22 in the nip portion N between the pressure pad 23 and the pressure belt 22, a polyimide having excellent slidability and high wear resistance. A sliding sheet (not shown) made of a glass fiber sheet impregnated with a film or a fluororesin is provided. Further, a lubricant such as amino-modified silicone oil or dimethyl silicone oil is applied to the inner peripheral surface of the pressure belt 22. As a result, the frictional resistance between the pressure belt 22 and the pressing pad 23 is reduced, and the pressure belt 22 rotates smoothly.

Next, the shapes of the fixing roll 21, the pressure belt 22, and the pressing pad 23 in a state where the pressing pad 23 presses the fixing roll 21 via the pressure belt 22 will be described. FIG. 4 is a diagram for explaining the shapes of the fixing roll 21, the pressure belt 22, and the pressure pad 23 according to the present embodiment.
4A is a cross-sectional view taken along the line IVA-IVA in FIG. 3, and is a cross-sectional view taken along the width direction of the fixing roll 21, the pressure belt 22, and the pressure pad 23. In FIG. 4A, the direction perpendicular to the paper surface (the direction from the back side of the paper surface to the front side of the paper surface) is the conveyance direction of the paper P conveyed through the nip portion N.
4B is a cross-sectional view along the width direction of the paper P passing through the nip portion N formed between the fixing roll 21 and the pressure belt 22 shown in FIG.

The pressing pad 23 of this embodiment is biased toward the fixing roll 21 by a biasing member (not shown) such as a coil spring. As a result, the pressure belt 22 positioned between the pressing pad 23 and the fixing roll 21 is pressed against the fixing roll 21.
In the following description, a state where the pressing pad 23 is urged toward the fixing roll 21 and the pressure belt 22 is pressed against the fixing roll 21 may be referred to as a “pressed state”.

In the pressurized state, the pressing pad 23 is elastically deformed so that the central portion in the width direction is convex toward the fixing roll 21 when viewed from the conveyance direction of the paper P as shown in FIG. Is bent. That is, the pressing pad 23 has a shape in which the central portion in the width direction protrudes toward the fixing roll 21 as compared with both end portions in the width direction and is curved from one end in the width direction to the other end in the width direction.
As a result, the fixing roll 21 is pressed against the pressing pad 23 via the pressure belt 22 and elastically deforms following the pressing pad 23. That is, as shown in FIG. 4A, in the fixing roll 21 in the region facing the pressing pad 23 through the pressure belt 22, the center portion in the width direction of the fixing roll 21 is compared with both end portions in the width direction. It is recessed on the side away from the pressing pad 23 and has a shape curved from one end in the width direction to the other end in the width direction.

  In the pressurized state, the fixing roll 21 and the pressure pad 23 have the above-described shape, so that the nip portion N formed between the fixing roll 21 and the pressure belt 22 is in the conveyance direction of the paper P. When viewed from the side, as shown in FIG. 4A, it is bent toward the fixing roll 21 side. That is, in the pressurized state, the central portion in the width direction of the nip portion N is recessed toward the fixing roll 21 as compared with the both end portions in the width direction, and the entire nip portion N is curved from one end in the width direction to the other end in the width direction. have. In the present embodiment, the deflection amount d of the nip portion N shown in FIG. 4A is, for example, about 0.8 mm to 1 mm.

In the present embodiment, the fixing roll 21 is rotationally driven in one direction (counterclockwise in FIG. 3) at a predetermined speed by a driving force of a driving motor (not shown). The pressure belt 22 provided in contact with the fixing roll 21 is driven to rotate in one direction (clockwise in FIG. 3) following the fixing roll 21 as the fixing roll 21 rotates. In other words, the pressure belt 22 rotates in conjunction with the fixing roll 21 by receiving a rotational driving force from the fixing roll 21.
The fixing device 20 is configured such that the fixing roll 21 and the pressure belt 22 can be separated from each other in order to cope with a paper jam or the like.

Next, a fixing operation performed by the fixing device 20 will be described.
When an operation for forming a toner image is started in the image forming apparatus 1 (see FIG. 1), a heater 21a (see FIG. 3) provided on the fixing roll 21 and a drive motor that drives the fixing roll 21 of the fixing apparatus 20 Power is supplied to (not shown). As a result, the fixing roll 21 generates heat and rotates, and the pressure belt 22 rotates as the fixing roll 21 rotates. The fixing roll 21 is heated to a predetermined temperature, and the pressure belt 22 is also heated via the fixing roll 21.
The fixing temperature at which the fixing roll 21 is heated is set to 180 ° C., for example.

  Next, in a state where the fixing roll 21 is heated to a predetermined temperature, the paper P having an unfixed toner image is sent to the nip portion N formed between the fixing roll 21 and the pressure belt 22. . In the nip portion N, the sheet P has a first surface P1 on which an unfixed toner image is formed facing the fixing roll 21 and a second surface P2 opposite to the first surface P1 facing the pressure belt 22. It is conveyed in the state. In the nip portion N, the unfixed toner image formed on the first surface P1 of the paper P is heated by the fixing roll 21 and fixed by being pressed by the fixing roll 21 and the pressure belt 22. Is done.

As described above, in this embodiment, the pressing pad 23 presses the fixing roll 21 via the pressure belt 22, so that the fixing roll 21 is elastically deformed into a shape in which the central portion in the width direction is recessed. . As a result, the nip portion N has a shape in which the central portion in the width direction is recessed toward the fixing roll 21 and is curved as a whole.
Therefore, as shown in FIG. 4B, the sheet P is subjected to the fixing process in a state in which the sheet P is curved following the nip portion N when viewed from the conveyance direction of the sheet P. More specifically, as shown in FIG. 4B, the sheet P is deformed so that the central portion in the width direction of the first surface P1 in contact with the fixing roll 21 is convex toward the fixing roll 21 side. The toner image is fixed on the first surface P1 of the paper P by being heated by the fixing roll 21.

Here, in the present embodiment, the fixing roll 21 is pressed by the pressing pad 23 and elastically deformed, so that the nip portion N formed between the fixing roll 21 and the pressure belt 22 becomes the fixing roll 21. It is wider than the case where it does not elastically deform.
Thereby, compared with the case where this configuration is not adopted, the contact area between the first surface P1 of the paper P and the fixing roll 21 is widened, and heat is transferred from the fixing roll 21 to the first surface P1 of the paper P. It becomes possible to improve the fixing performance of the toner image on the first surface P1 of the paper P.
Compared with the case where this configuration is not adopted, the contact area between the first surface P1 of the paper P and the fixing roll 21 and the contact area between the second surface P2 of the paper P and the pressure belt 22 in the nip portion N are compared. Both of these are widened, and it is possible to improve the conveyance performance of the paper P by the fixing roll 21 and the pressure belt 22.

Subsequently, the sheet P that has been subjected to the fixing process in the nip portion N is peeled off from the fixing roll 21 and the pressure belt 22 and conveyed toward the discharge device 70 while being deformed into the shape described above. Become.
As shown in FIG. 3, in the fixing unit 80 of the present embodiment, the direction in which the paper P is sent out from the fixing device 20 is different from the direction in which the paper P is inserted into the discharge device 70. Therefore, in the present embodiment, as shown in FIG. 3, a curved portion YRC that bends from the fixing device 20 toward the discharge device 70 is formed in the paper transport path YR as an example of the transport path. In this embodiment, the sheet P sent out from the fixing device 20 is bent and conveyed by the curved portion YRC so that the first surface P1 of the sheet P is inside, and then sent to the discharge device 70. .

In the fixing unit 80 of the present embodiment, the length of the sheet conveyance path YR between the fixing device 20 and the discharge device 70 is formed short in order to reduce the size of the fixing unit 80 and the image forming apparatus 1. Yes. In this example, the length of the paper transport path YR between the fixing device 20 and the discharge device 70 is shorter than the width (210 mm) of A4 size paper that is frequently used as the paper P.
Thus, in the present embodiment, for example, when image formation is performed on an A4 size paper P, when the leading side in the transport direction of the paper P is sent out from the fixing device 20 and reaches the discharge device 70, The rear end side in the conveyance direction of the paper P is in a state of being sandwiched by the nip portion N of the fixing device 20.

Here, in general, in the discharge device 70 that discharges the paper P on which an image has been formed from the image forming apparatus 1 to the outside of the apparatus, a technique for forming a corrugation along the width direction on the discharged paper P is known. ing. In this way, by forming corrugation on the paper P, the stiffness of the paper P along the paper transport direction in the paper transport path YR becomes strong, and when the paper P is discharged from the discharge device 70, the paper stacking unit YS. In (see FIG. 1), the paper P is discharged to a position away from the discharge device 70, and the stackability of the paper P in the paper stacking portion YS is improved.
However, when the sheet P is bent along the width direction in the fixing device 20 and then conveyed to the discharge device 70 through the bent sheet conveyance path YR having the curved portion YRC as in the present embodiment. In some cases, the curve formed on the paper P in the fixing device 20 and the corrugation formed on the paper P in the discharge device 70 collide with each other at the curved portion YRC of the paper transport path YR. It was.

  In particular, in the fixing device 20, the paper P is curved so that the central portion in the width direction of the first surface P1 of the paper P is convex, and in the discharge device 70, the central portion in the width direction of the first surface P1 in the paper P is formed. When corrugation is formed on the paper P so as to be convex, the force acting from the fixing device 20 side of the paper P due to the curvature of the paper P and the corrugation of the paper P in the curved portion YRC of the paper transport path YR. There is a possibility that the force acting from the discharge device 70 side of the paper P collides and the paper P is wrinkled.

  Therefore, in the present embodiment, the fixing device 20 performs the fixing process while deforming the sheet P so that the central portion in the width direction of the first surface P1 of the sheet P is convex, and the fixing device 20 performs the fixing process of the sheet P. In the fixing unit 80 in which the paper P is conveyed to the discharge device 70 through a path curved to the first surface P1, the first surface P1 of the paper P in the discharge device 70 in order to suppress the generation of wrinkles in the paper P. The sheet P is deformed so that the center part in the width direction becomes concave (that is, the center part in the width direction of the second surface P2 becomes convex).

Then, the structure of the discharge device 70 of this Embodiment is demonstrated.
FIG. 5 is a diagram for explaining the configuration of the discharge device 70 of the present embodiment. Fig.5 (a) is the front view which looked at the discharge apparatus 70 of FIG. 3 from VA direction. FIG. 5B is a cross-sectional view along the width direction of the paper P discharged from the discharge device shown in FIG.
As shown in FIG. 5A and FIG. 2 described above, the discharge device 70 of the present embodiment includes a drive shaft 73 extending along the width direction, a first roll shaft 71 facing the drive shaft 73, and a first roll shaft 71. A second roll shaft 72 is provided opposite to the first roll shaft 71 and provided on the opposite side of the drive shaft 73 with respect to the first roll shaft 71.

The drive shaft 73 is provided in the housing 81 along the width direction. A cylindrical drive roll 73 a is fixed to the drive shaft 73 at the center in the width direction of the drive shaft 73. The drive roll 73a is preferably formed of an elastic body.
The drive shaft 73 receives a drive force from a drive motor (not shown) provided at the end in the width direction of the drive shaft 73, and is driven to rotate in one direction (clockwise in FIG. 3) at a predetermined speed. . As the drive shaft 73 rotates, the drive roll 73 a provided on the drive shaft 73 also rotates in the same direction as the drive shaft 73.

The first roll shaft 71 is provided in the housing 81 so as to face the drive shaft 73. As shown in FIG. 5, the first roll shaft 71 has a width from one end in the width direction so that the central portion in the width direction is convex toward the side opposite to the drive shaft 73 (the second roll shaft 72 side described later). It has a curved shape toward the other end in the direction.
In addition, a columnar first transport roll 71 a is provided at the center in the width direction of the first roll shaft 71. The first transport roll 71a is provided so as to be rotatable with respect to the first roll shaft 71, and the outer peripheral surface thereof is provided in contact with the outer peripheral surface of the drive roll 73a and the outer peripheral surface of the second transport roll 72a described later. Yes. Thereby, the 1st conveyance roll 71a follows the drive roll 73a and is driven to rotate in one direction (counterclockwise in FIG. 3) as the drive roll 73a rotates. In addition, it is preferable to form the 1st conveyance roll 71a with an elastic body.

  Furthermore, on the one end side in the width direction of the first roll shaft 71 from the first transport roll 71a, the first corrugation roll 71b1, the first opposing roll 71c, and the first corrugation from the center in the width direction toward the one end in the width direction. Rolls 71b2 are provided in order. Moreover, in this Embodiment, the roll provided in the 1st roll axis | shaft 71 and the 1st roll axis | shaft 71 has the width direction one end side and the width direction other end side of the 1st roll axis | shaft 71 centering on the 1st conveyance roll 71a. It has the same configuration. That is, as shown in FIG. 5, the first corrugation roll 71b1, the first opposing roll 71c, and the first corrugation roll 71b2 are sequentially arranged on the other end side of the first roll shaft 71 in the width direction with respect to the first transport roll 71a. It is provided side by side.

Each of the first corrugation rolls 71b1 and 71b2 has a so-called taper shape in which the outer diameter gradually decreases toward the side closer to the first opposing roll 71c. Each of the first corrugation rolls 71b1 and 71b2 is rotatably provided with the first roll shaft 71 as a central axis.
In addition, the first opposing roll 71c is configured by a plurality of (in this example, five) rolls each having a cylindrical shape, and each of the first opposed rolls 71c is rotatably provided with the first roll shaft 71 as a central axis. In addition, the outer diameter of the 1st opposing roll 71c is formed small compared with the outer diameter of 1st corrugation roll 71b1, 71b2.

The second roll shaft 72 is provided in the housing 81 so as to face the first roll shaft 71. As shown in FIG. 5, the second roll shaft 72 has a curved shape from one end in the width direction to the other end in the width direction so that the central portion in the width direction is convex toward the side opposite to the first roll shaft 71. Have.
In addition, a columnar second transport roll 72 a is provided at the center in the width direction of the second roll shaft 72. The second transport roll 72a is provided to be rotatable with respect to the second roll shaft 72, and the outer peripheral surface thereof is provided in contact with the outer peripheral surface of the first transport roll 71a. Thus, as the first transport roll 71a rotates following the drive roll 73a, the first transport roll 71a follows and rotates in one direction (clockwise in FIG. 3). In addition, it is preferable to form the 2nd conveyance roll 72a with an elastic body.

  Furthermore, the second corrugation roll 72b1, the second opposing roll 72c, and the second corrugation roll are arranged on one end side in the width direction of the second roll shaft 72 from the center in the width direction toward one end in the width direction. 72b2 are provided in order. Moreover, in this Embodiment, the roll provided in the 2nd roll axis | shaft 72 and the 2nd roll axis | shaft 72 has the width direction one end side and the width direction other end side of the 2nd roll axis | shaft 72 centering on the 2nd conveyance roll 72a. It has the same configuration. That is, as shown in FIG. 5, the second corrugation roll 72b1, the second opposing roll 72c, and the second corrugation roll 72b2 are sequentially provided on the other end side of the second roll shaft 72 in the width direction with respect to the second transport roll 72a. It is provided side by side.

Each of the second corrugation rolls 72b1 and 72b2 has a so-called taper shape in which the outer diameter gradually decreases toward the side closer to the second opposing roll 72c. Each of the second corrugation rolls 72b1 and 72b2 is rotatably provided with the second roll shaft 72 as a central axis.
The second opposing roll 72c is configured by a plurality of (in this example, five) rolls each having a cylindrical shape, and each of the second opposed rolls 72c is rotatably provided with the second roll shaft 72 as a central axis. In addition, the external shape of the 2nd opposing roll 72c is formed small compared with the outer diameter of 2nd corrugation roll 72b1, 72b2.

In the present embodiment, the second opposing roll 72 c provided on the second roll axis 72 is opposed to the first corrugation roll 71 b 2 provided on the first roll axis 71 and provided on the second roll axis 72. The first opposing roll 71c provided on the first roll shaft 71 is opposed to the second corrugation roll 72b1. The first corrugation roll 71b1 provided on the first roll shaft faces the second roll shaft 72, and the second corrugation roll 72b2 provided on the second roll shaft 72 faces the first roll shaft 71. ing.
In the following description, the first transport roll 71a and the second transport roll 72a may be collectively referred to as a transport roll. The first corrugation rolls 71b1 and 71b2 and the second corrugation rolls 72b1 and 72b2 may be collectively referred to as corrugation rolls. Furthermore, the 1st opposing roll 71c and the 2nd opposing roll 72c may be collectively called an opposing roll.

Next, the paper P discharging operation performed by the discharging device 70 will be described.
In the image forming apparatus 1 (see FIG. 1), when an operation for forming a toner image is started, electric power is supplied to a drive motor (not shown) that drives a drive shaft 73 in the discharge device 70. Thereby, the drive roll 73a provided in the drive shaft 73 and the drive shaft 73 rotates. Further, the first transport roll 71a rotates following the rotation of the drive roll 73a, and the second transport roll 72a rotates following the rotation of the first transport roll 71a.

Next, the toner image is fixed by the fixing device 20, and the paper P transported through the paper transport path YR is sent between the first roll shaft 71 and the second roll shaft 72. At this time, of the paper P, the first surface P1 on which the toner image is fixed faces the first roll shaft 71, and the second surface P2 opposite to the first surface P1 faces the second roll shaft 72. . The fed paper P is sandwiched between a first transport roll 71 a provided on the first roll shaft 71 and a second transport roll 72 a provided on the second roll shaft 72. As the first transport roll 71a and the second transport roll 72a rotate, the first surface P1 of the paper P is guided to the first transport roll 71a, and the second surface P2 of the paper P is guided to the second transport roll 72a. As a result, the paper P is transported between the first roll shaft 71 and the second roll shaft 72.
When the paper P is transported between the first roll shaft 71 and the second roll shaft 72, the first corrugation rolls 71b1, 71b2 and the first opposing roll 71c come into contact with the first surface P1 of the paper P. Thus, the paper P rotates following the movement of the paper P. Similarly, the second corrugation rolls 72b1 and 72b2 and the second opposing roll 72c rotate by following the movement of the paper P by contacting the second surface P2 of the paper P.

  Then, as the paper P is transported between the first roll shaft 71 and the second roll shaft 72 by the first transport roll 71a and the second transport roll 72a, the first corrugation rolls 71b1, 71b2, The two corrugation rolls 72b1 and 72b2, the first opposing roll 71c, and the second opposing roll 72c change the shape of the cross section along the width direction as shown in FIG. 5B, and then discharge to the paper stacking unit YS. Is done.

Next, the shape of the paper P that is deformed by being conveyed between the first roll shaft 71 and the second roll shaft 72 will be specifically described.
In the region of the paper P where the first corrugation rolls 71b1 and 71b2 are in contact with the first surface P1, the paper P is pushed toward the second surface P2 by the first corrugation rolls 71b1 and 71b2. In the region where the second corrugation rolls 72b1 and 72b2 are in contact with the second surface of the paper P, the paper P is pushed toward the first surface P1 by the second corrugation rolls 72b1 and 72b2.

  Thereby, the sheet P is deformed into a shape in which the second surface P2 side is convex (that is, the first surface P1 side is concave) in the region where the first corrugation rolls 71b1 and 71b2 are in contact with the first surface P1. In addition, in the region where the second corrugation rolls 72b1 and 72b2 are in contact with the second surface, the first surface P1 side is deformed (that is, the second surface P2 side is concave). Thereby, as described above, the cross section along the width direction of the sheet P conveyed between the first roll shaft 71 and the second roll shaft 72 of the discharge device 70 is from the width direction one end to the width direction other end. On the other hand, a portion where the second surface P2 side is convex and a portion where the first surface P1 side is convex are alternately repeated, and corrugation is formed on the paper P.

Further, as shown in FIG. 5A, the first roll shaft 71 and the second roll shaft 72 of the present embodiment are such that the central portion in the width direction protrudes toward the side opposite to the drive shaft 73. It has a shape curved from one end in the width direction to the other end in the width direction. A corrugation roll and a counter roll are provided for the first roll shaft 71 and the second roll shaft 72 that are curved in this manner.
As a result, the paper P that has passed between the first roll shaft 71 and the second roll shaft 72 and has been deformed by the corrugation roll and the opposing roll has a width as a whole as shown in FIG. It is deformed into a shape along a curved curve from one end in the direction to the other end in the width direction. Specifically, as shown in FIG. 5B, the cross section along the width direction of the paper P has a central portion in the width direction that protrudes most toward the second surface P <b> 2 side of the paper P, and both end portions in the width direction. In the paper P, the shape is the most drooping on the first surface P1 side.

  As described above, in the present embodiment, in the discharge device 70, the paper P projects from the center in the width direction toward the second surface P2 and the both ends in the width direction hang down toward the first surface P1. The entire sheet P is deformed so as to have a shape along a curve that curves from one end in the width direction to the other end in the width direction. Thereby, in the discharge device 70, compared to the case where the paper P is deformed so that the central portion in the width direction protrudes toward the second surface side, the curved portion YRC of the paper transport path YR is compared with the paper P. Thus, collision between the force acting from the fixing device 20 side and the force acting from the discharge device 70 side on the paper P is suppressed. Therefore, in the present embodiment, it is possible to prevent the paper P from being wrinkled at the curved portion YRC of the paper transport path YR.

  Further, in the present embodiment, in the discharge device 70, with respect to the paper P, the central portion in the width direction of the second surface P2 of the paper P is convex (that is, the central portion in the width direction of the first surface P1 is concave), and From the width direction one end to the width direction other end, it becomes convex toward the second surface P2 side (the first surface P1 side becomes concave) and convex toward the first surface P1 side (second Corrugations are formed in such a manner that the portions where the surface P2 side is concave) are alternately repeated. Thereby, compared with the case where such corrugation is not formed on the paper P in the discharge device 70, the stiffness of the paper P along the paper transport direction in the paper transport path YR becomes stronger, and the paper P is discharged from the discharge device 70. Is discharged to a position away from the discharge device 70 in the paper stacking unit YS. Therefore, compared with the case where this configuration is not adopted, it is possible to suppress a decrease in the stackability of the paper P discharged from the discharge device 70 in the paper stacking unit YS.

In the discharge device 70 of the present embodiment, a second facing roll 72c is provided so as to face the first corrugation roll 71b2. Then, the paper P is conveyed while being sandwiched between the first corrugation roll 71b2 and the opposing roll 72c. Thereby, in the area pressed by the first corrugation roll 71b2, the paper P is prevented from being bent sharply toward the second roll shaft 72, and the paper P discharged from the discharge device 70 is creased. Can be suppressed.
Similarly, in this Embodiment, the 1st opposing roll 71c is provided so that the 2nd corrugation roll 72b1 may be opposed. Thereby, it is possible to suppress the paper P from being bent sharply toward the first roll shaft 71, and to suppress the folding of the paper P discharged from the discharge device 70.

  In the present embodiment, in the discharge device 70, the paper P projects from the paper P to the second surface P2 side most in the width direction, and both ends in the width direction hang from the first surface P1 side most in the paper P. In addition, from the one end in the width direction toward the other end in the width direction, a waveform shape in which a portion that protrudes toward the second surface P2 and a portion that protrudes toward the first surface P1 are alternately repeated did.

However, in the discharge device 70, the second surface P2 of the paper P is convex at least in the width direction central portion of the paper P (that is, the first surface P1 side is concave in the width direction central portion of the paper P). ), Both ends in the width direction may be deformed into a shape that hangs down on the first surface P1 side of the paper P.
In the discharge device 70, by deforming the sheet P into such a shape, for example, compared to a case where the sheet P is deformed into a shape in which the central portion in the width direction is convex toward the first surface P1, the sheet transport path YR. It is possible to prevent the paper P from being wrinkled at the curved portion YRC.
Further, by changing the paper P to such a shape in the discharge device 70, for example, compared with the case where the discharge device 70 does not form irregularities on the paper P, the paper P in the paper stacking unit YS is changed. It is possible to suppress the loadability from deteriorating.

  Moreover, in this Embodiment, the 1st roll axis | shaft 71 and the 2nd roll axis | shaft 72 are made into the shape which curved from the width direction one end to the width direction other end, and the conveyance roll and corrugation roll provided in these axes | shafts The paper P was deformed into a shape along a curved curve from one end in the width direction to the other end in the width direction by the opposing roll. However, the first roll shaft 71 and the second roll shaft 72 are not necessarily curved. For example, while providing the 1st roll axis | shaft 71 and the 2nd roll axis | shaft 72 along the width direction, the diameter of the corrugation roll and opposing roll provided in the 1st roll axis | shaft 71 and the 2nd roll axis | shaft 72 is set to the width direction center part and width | variety. The paper P can be deformed into the above-described shape by making it different from the direction end.

Further, in the present embodiment, the paper P is deformed by a plurality of corrugation rolls and opposing rolls separated along the width direction. However, the deformation of the sheet P is not necessarily performed by a plurality of rolls separated in the width direction. For example, the sheet P is integrally provided along the width direction and has a curved shape from one end in the width direction to the other end in the width direction. The paper P may be deformed by bringing the roll-shaped members and the like having contact with the first surface P1 side and the second surface P2 side of the paper P, respectively.
Furthermore, in the present embodiment, the first roll shaft 71 and the second roll shaft 72 that support the transport roll, the corrugation roll, and the opposing roll are each integrally formed from one end in the width direction to the other end in the width direction. However, for example, the first roll shaft 71 or the second roll shaft 72 may be divided into a plurality of roll shafts along the width direction, and each of the plurality of roll shafts may hold a roll.

  In the present embodiment, the discharge device 70 is configured to deform the sheet P conveyed on the sheet conveyance path YR and to discharge the deformed sheet P to the outside of the fixing unit 80. However, for example, an apparatus for deforming the sheet P conveyed on the sheet conveyance path YR and an apparatus for discharging the sheet P to the outside of the fixing unit 80 may be provided separately.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 20 ... Fixing device, 21 ... Fixing roll, 22 ... Pressure belt, 23 ... Pressing pad, 70 ... Discharging device, 71 ... 1st roll axis, 72 ... 2nd roll axis, 73 ... Drive axis 80: fixing unit, 100: image forming unit, P: paper, YR: paper transport path, YRC: curved portion, YS: paper stacking unit

Claims (5)

A fixing member that is rotatably provided, extends from one end to the other along the rotation axis, and elastically deforms;
The fixing member is pressed to form a fixing nip portion with the fixing member, and the fixing member is elastically formed so that the shape along the rotation axis direction of the fixing member is concave or convex in the fixing nip portion. deforming, by passing the recording material to the fixing nip portion, while deforming the recording material so that the central portion of the rotational axis direction has a convex shape in one side of the recording material the toner image on the recording medium A pressure member for fixing
A conveyance path for conveying the recording material, on which the toner image has been fixed at the fixing nip, via a curved portion curved so that the one surface side is inside;
A conveyance unit that is further provided on the downstream side in the conveyance direction from the curved portion in the conveyance path, and conveys the recording material that has been fixed and conveyed ;
The transport means includes a first transport shaft facing the one surface of the recording material transported extending along the rotation axis direction, and the other of the recording material transported extending along the rotation shaft direction. And a second transport shaft facing the first transport shaft across the recording material, and the first transport shaft and the second transport shaft have a central portion in the rotational axis direction of the first transport shaft. The recording material has a shape that is curved so as to protrude in a direction from the first conveyance axis toward the second conveyance axis, and the recording material is passed between the first conveyance axis and the second conveyance axis. A fixing unit for transporting the recording material while deforming the recording material so that the central portion in the rotation axis direction on the one surface is concave . The fixing member is provided on a side facing the one surface of the recording material on which the unfixed toner image is formed on the one surface, upstream of the curved portion in the transport path in the transport direction. And
It said pressure member, together with the fixing member is elastically deformed so that the shape along the rotation axis direction of the fixing member by pressing the fixing member is concave, in the one surface of the recording material the fixing unit according to claim 1, wherein the central portion of the rotational axis direction and wherein the deforming the recording material so as to be convex. The conveying means records the recording material in such a manner that, on the one surface of the recording material after fixing, concaves and convexes are alternately arranged along the rotational axis direction, and a central portion in the rotational axis direction is concave. 3. The fixing unit according to claim 1, wherein the recording material is deformed and the deformed recording material is discharged to the outside. Wherein said first conveying axis of the conveying means has a plurality of first roll member that is separated into the rotation axis direction, the second transport axis, the plurality of second roll member that is separated into the rotary axis has the said one surface of the recording material is brought into contact with the first roll member, by contacting the second roll member to the other surface of the recording medium, the one surface of the recording medium 4. The fixing unit according to claim 3, wherein the recording material is deformed so that concaves and convexes are alternately arranged along the rotation axis direction and a central portion in the rotation axis direction is concave. 5. . Toner image forming means for forming a toner image;
Transfer means for transferring the toner image formed by the toner image forming means onto a recording material;
Fixing means for fixing the toner image transferred onto the recording material by the transfer means to the recording material;
The fixing means is
A fixing member that is rotatably provided, extends from one end to the other along the rotation axis, and elastically deforms;
The fixing member is pressed to form a fixing nip portion with the fixing member, and the fixing member is elastically formed so that the shape along the rotation axis direction of the fixing member is concave or convex in the fixing nip portion. deforming, by passing the recording material to the fixing nip portion, while deforming the recording material so that the central portion of the rotational axis direction has a convex shape in one side of the recording material the toner image on the recording medium A pressure member for fixing
A conveyance path for conveying the recording material, on which the toner image has been fixed at the fixing nip, via a curved portion curved so that the one surface side is inside;
A conveyance unit that is further provided on the downstream side in the conveyance direction from the curved portion in the conveyance path, and conveys the recording material that has been fixed and conveyed ;
The conveyance unit of the fixing unit includes a first conveyance axis that faces the one surface of the recording material that is conveyed along the rotation axis direction, and the recording that is conveyed along the rotation axis direction. A second transport shaft facing the other surface of the material and facing the first transport shaft across the recording material, the first transport shaft and the second transport shaft being in the center in the rotational axis direction The portion has a curved shape so as to protrude in a direction from the first conveyance axis toward the second conveyance axis, and the recording material is passed between the first conveyance axis and the second conveyance axis. An image forming apparatus , wherein the recording material is conveyed while being deformed so that a central portion in the rotation axis direction on the one surface of the recording material is concave .

Images