JP5920253B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

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

  In an image forming apparatus such as a copying machine or a printer, a fixing device that fixes an image on a recording medium is used. As a fixing device for heating and fixing an unfixed toner image, for example, a belt nip type fixing device using an endless belt is known.

  In order to reduce the sliding resistance between the endless belt and the pad member, a pad sheet coated with a low-friction surface layer and bonded to the pad member is known (for example, see Patent Document 1).

JP 2006-119263 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device and an image forming apparatus that suppress image disturbance and defects.

The invention according to claim 1 is provided with an endless belt that contacts and conveys a recording medium, a pressure member that contacts and pressurizes the recording medium, and an inner side of the belt facing the pressure member. A pressure-receiving member that receives pressure from the pressure member, a heating source that heats the belt, and a sheet that reduces friction between the belt and the pressure-receiving member, , between the upstream end in the conveying direction of the recording medium to the region where the sheet is pressed toward the downstream have a plurality of cuts, the cuts spacing of both end portions of the sheet, the central portion The fixing device is characterized by being narrower than the notch interval .

  The invention according to claim 2 is the fixing device according to claim 1, wherein the sheet is provided with a non-pressurized area between the notch and the pressurized area. .

  According to a third aspect of the present invention, in the fixing device according to the first or second aspect, the cutting direction is substantially parallel to the transport direction.

According to a fourth aspect of the present invention, there is provided an image forming apparatus comprising the fixing device according to any one of the first to third aspects, wherein an image is formed on the recording medium.

According to the first aspect of the present invention, it is possible to provide a fixing device in which image distortion and defects are suppressed as compared with the case where the present configuration is not provided. According to the second and third aspects of the invention, it is possible to provide a fixing device in which image distortion and defects are further suppressed as compared with the case where the present configuration is not provided. According to a fourth aspect of the present invention, there is provided an image forming apparatus that suppresses a reduction in image quality of an output image as compared with the case where the fixing device according to any one of the first to third aspects is not provided. Can be provided.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment. FIG. 2 is a schematic cross-sectional configuration diagram of a fixing device. The schematic perspective view of a pressure roll and a to-be-pressurized member. FIG. 3 is a schematic enlarged side view of a pressure roll and a member to be pressed around the nip portion. The expansion | deployment partial top view of a sliding sheet. The partial schematic diagram when heat is applied to the sliding sheet. The schematic diagram when heat | fever is added to the sliding sheet | seat which does not form a notch as a comparison. The expansion | deployment partial top view of the sliding sheet | seat 632A of a modification.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram illustrating a configuration example of an image forming apparatus 1 according to the embodiment. The image forming apparatus 1 shown in FIG. 1 controls the operation of the entire image forming apparatus 1, which is an example of an image forming unit that forms an image based on image data, communication with, for example, a personal computer, image data, and the like. A main control unit 50 that executes image processing and the like performed on the user interface, and a UI unit (user interface unit) 90 that receives an operation input from the user and displays various information for the user.

  The image forming unit 10 includes an image forming unit that forms an image by electrophotography, for example. The image forming unit includes six image forming units 11C, 11M, 11HC, 11HM, 11Y, and 11K arranged in parallel.

  Each image forming unit includes, for example, a photosensitive drum 12 on which an electrostatic latent image is formed and each color toner image is formed thereafter, and a charger 13 that charges the surface of the photosensitive drum 12 with a predetermined potential. An exposure unit 14 that exposes the photosensitive drum 12 charged by the charger 13 based on image data; a developing unit 15 that develops the electrostatic latent image formed on the photosensitive drum 12 with each color toner; and a transfer unit. And a cleaner 16 for cleaning the surface of the subsequent photosensitive drum 12.

  The developing device 15 of each image forming unit is connected to toner containers 17C, 17M, 17HC, 17HM, 17Y, and 17K that store toner of each color by a toner conveyance path (not shown). Each color toner is supplied from each toner container to the developing device 15 by a replenishing screw provided in the toner conveyance path.

  Each image forming unit is configured in substantially the same manner except for the toner accommodated in the developing device 15, and each of them is C (cyan), M (magenta), HC (high chroma cyan), and HM (high chroma magenta). , Y (yellow) and K (black) toner images are formed. The HC color here is a cyan color having a cyan hue, a hue that is brighter and higher in saturation than the C color, and the HM color has a magenta hue, and M color. It is a magenta color with a brighter color tone and a relatively high saturation.

  The image forming unit 10 also includes an intermediate transfer belt 20 to which each color toner image formed on the photosensitive drum 12 of each image forming unit is transferred, and each color toner image formed by each image forming unit to the intermediate transfer belt. And a primary transfer roll 21 to be transferred to the printer 20.

  The image forming unit 10 also includes a secondary transfer roll 22 that batch-transfers each color toner image transferred onto the intermediate transfer belt 20 onto a sheet P, which is an example of a recording medium, and each color toner that has been secondarily transferred. And a fixing device 60 for fixing the image on the paper P. Here, an area where the secondary transfer roll 22 is disposed and each color toner image on the intermediate transfer belt 20 is secondarily transferred to the paper P is referred to as a secondary transfer area Tr.

  Further, the image forming unit 10 cools each color toner image fixed on the paper P by the fixing device 60, and the cooling unit 80 that promotes fixing of the color toner image on the paper P, and the bending of the paper P. And a straightening unit 85 for straightening.

Hereinafter, a paper transport system for forming an image on one side of the paper P will be described.
In the embodiment in which the paper P is accommodated as the paper conveyance system, the image forming unit 10 includes two paper storage containers 40A and 40B, and a feeding roll 41A that feeds and transports the paper P stored in the paper storage containers 40A and 40B. , 41B, a first transport path R1 for transporting the paper P from the paper storage container 40A, and a second transport path R2 for transporting the paper P from the paper storage container 40B.

Further, the image forming unit 10 includes a third transport path R3 that transports the paper P from the paper storage container 40A and the paper storage container 40B toward the secondary transfer region Tr. Further, the image forming unit 10 conveys the paper P on which the toner image of each color is transferred in the secondary transfer region Tr so as to pass through the fixing device 60, the cooling unit 80, and the curl correction unit 85. And a fifth transport path R5 for transporting the paper P from the curl correction unit 85 toward the paper stacking section 44 provided in the discharge section of the image forming apparatus 1.
From the first conveyance path R1 to the fifth conveyance path R5, conveyance rolls and conveyance belts are arranged along the respective conveyance paths, and sequentially convey the fed paper P.

Hereinafter, a paper conveyance system when images are formed on both sides of the paper P will be described.
As the double-sided conveyance system, the image forming unit 10 temporarily holds the paper P on which the color toner images are fixed on the first surface by the fixing device 60 and the paper P from the curl correction unit 85 as the intermediate paper. A sixth transport path R6 for transporting toward the storage container 42 and a seventh transport path R7 for transporting the paper P stored in the intermediate paper storage container 42 toward the third transport path R3 are provided.
The image forming unit 10 is disposed downstream of the curl correction unit 85 in the sheet conveyance direction, and conveys the sheet P toward the sheet stacking unit 44 and a sixth conveyance path R5 that conveys the sheet P to the intermediate sheet storage container 42. A distribution mechanism unit 43 that selectively distributes the sheet P to the transport path R6 and a feeding roll 45 that feeds the sheet P stored in the intermediate sheet storage container 42 and transports the sheet P toward the seventh transport path R7 are provided.

Next, a basic image forming operation in the image forming apparatus 1 will be described.
Each image forming unit of the image forming unit 10 forms each color toner image of C color, M color, HC color, HM color, Y color, and K color by an electrophotographic process using the above functional members. Each color toner image formed by each image forming unit is primary-transferred sequentially on the intermediate transfer belt 20 by the primary transfer roll 21 to form a composite toner image on which the respective color toners are superimposed. The synthetic toner image on the intermediate transfer belt 20 is conveyed to the secondary transfer region Tr in which the secondary transfer roll 22 is disposed as the intermediate transfer belt 20 moves (in the direction of the arrow).

  On the other hand, in the paper transport system, the feeding rolls 41A and 41B rotate in accordance with the start timing of image formation in each image forming unit, and are designated by, for example, the UI unit 90 from the paper container 40A and the paper container 40B. The fed paper P is fed out by feeding rolls 41A and 41B. The paper P fed out by the feed rolls 41A and 41B is transported along the first transport path R1 or the second transport path R2 and the third transport path R3 and reaches the secondary transfer region Tr. In the secondary transfer region Tr, the composite toner image held on the intermediate transfer belt 20 is secondarily transferred onto the paper P collectively by the transfer electric field formed by the secondary transfer roll 22.

  Thereafter, the sheet P on which the composite toner image is transferred is separated from the intermediate transfer belt 20 and conveyed to the fixing device 60 along the fourth conveyance path R4. The composite toner image on the paper P conveyed to the fixing device 60 is fixed on the paper P by being subjected to a fixing process by the fixing device 60. The paper P on which the fixed image is formed is cooled by the cooling unit 80 and the curl correction unit 85 corrects the bending of the paper P. Thereafter, the paper P that has passed through the curl correction unit 85 is guided by the distribution mechanism unit 43 to the fifth transport path R5 during single-sided printing and transported toward the paper stacking unit 44. The toner (primary transfer residual toner) attached to the photosensitive drum 12 after the primary transfer and the toner (secondary transfer residual toner) attached to the intermediate transfer belt 20 after the secondary transfer are respectively cleaners. 16 and belt cleaner 26.

  On the other hand, during double-sided printing, the paper P on which the fixed image is formed on the first surface of the paper P by the above-described process passes through the curl correction unit 85 and is then guided to the sixth transport path R6 by the distribution mechanism unit 43. Then, the paper is transported through the sixth transport path R6 toward the intermediate paper storage container. Then, the feeding roll 45 rotates again in accordance with the start timing of image formation on the second surface by each image forming unit 11, and the paper P is fed out from the intermediate paper storage container 42. The paper P fed out by the feed roll 45 is transported along the seventh transport path R7 and the third transport path R3 and reaches the secondary transfer region Tr. In the secondary transfer region Tr, each color toner image on the second surface held on the intermediate transfer belt 20 is applied to the paper P by the transfer electric field formed by the secondary transfer roll 22 as in the case of the first surface. Secondary transfer is performed at once.

  The paper P with the toner images transferred on both sides is fixed by the fixing device 60 as in the case of the first side, cooled by the cooling unit 80, and further, the curl correction unit 85 corrects the bending of the paper P. Is done. Thereafter, the paper P that has passed through the curl correction unit 85 is guided to the fifth transport path R5 by the distribution mechanism unit 43 and transported toward the paper stacking unit 44. 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 device 60 used in the image forming apparatus 1 of the embodiment will be described.
FIG. 2 is a schematic cross-sectional configuration diagram for explaining the configuration of the fixing device 60 of the embodiment.
In FIG. 2, a fixing device 60 is an example of a fixing belt module 61 that heats a sheet P and a pressurizing member that is configured to be able to contact with and separate from the fixing belt module 61 and presses the sheet P in contact therewith. The main part is composed of the pressure roll 62.

  The fixing belt module 61 is provided on the inner side of the fixing belt 610 as an example of an endless belt that contacts and conveys the paper P and is opposed to the pressure roll 62. A member to be pressurized 63 that receives pressure. The pressed member 63 heats the fixing belt 610 from the inside at the nip portion Np, which is a region where the fixing belt 610 and the pressure roll 62 come into contact with each other while being pressed. The width of the nip portion Np in the transport direction is, for example, about 10 mm.

The fixing belt module 61 includes internal heating rolls 612 and 613 that heat the fixing belt 610 while stretching the fixing belt 610 from the inside.
The internal heating rolls 612 and 613 are cylindrical rolls made of, for example, aluminum or SUS. At least one of the internal heating rolls 612 and 613 receives a rotational driving force from a driving motor (not shown), rotates in the direction of the arrow in the figure, and drives the fixing belt 610.

  In addition, halogen heaters 70, 71, and 72, which are examples of heating sources, are disposed inside the internal heating rolls 612 and 613 and the pressed member 63, respectively. The internal heating rolls 612 and 613 and the pressed member 63 are The predetermined temperature, for example, the internal heating rolls 612 and 613 are heated to 210 ° C., and the pressed member 63 is heated to 200 ° C.

Spring members (not shown) that press the fixing belt 610 from the inside to the outside are arranged at both ends of the internal heating rolls 612 and 613 and the member to be pressed 63, and the tension of the entire fixing belt 610 is set to 15 kgf, for example. doing.
As described above, the fixing device 60 according to the embodiment employs a configuration in which the fixing belt 610 is heated by the pressed member 63 and the internal heating rolls 612 and 613.
Here, although not shown, a tension roll for stretching the fixing belt 610 may be provided in addition to the internal heating rolls 612 and 613.

  The fixing belt 610 includes, for example, a base layer made of polyimide resin and an elastic layer made of silicone rubber laminated on the surface side (outer peripheral surface side) of the base layer. Here, the elastic layer is provided particularly for improving the image quality of a color image. The toner image held on the sheet P to be fixed is formed by laminating each color toner as powder. Therefore, in order to supply heat uniformly to the entire toner image at the nip portion Np, it is preferable that the surface of the fixing belt 610 be deformed following the unevenness of the toner image on the paper P.

  FIG. 3 is a schematic perspective view of the pressure roll 62 and the pressed member 63, and FIG. 4 is a schematic enlarged side view of the pressure roll 62 and the pressed member 63 around the nip portion Np. In FIG. 3, the paper P is indicated by a broken line, and the fixing belt 610 is indicated by a one-dot chain line. In FIG. 4, the flow of the paper P is indicated by a broken line arrow, and the direction in which the fixing belt 610 is driven is indicated by a solid line arrow.

  3 and 4, the member to be pressed 63 is a pad provided on the side of the base material 630 facing the pressure roll 62 of the base material 630 whose outer shape is made of aluminum or SUS, for example. 631. The pad 631 may be formed of the same material as the base material 630, or may be made of another material, for example, a resin. The corners C on the upstream side and the downstream side of the pad 631 are formed with a curvature.

Further, the fixing belt module 61 includes a sliding sheet 632 which is an example of a resin sheet provided from the upstream side of the base material 630 in the conveyance direction of the paper P to the downstream side so as to cover the pad 631. The sliding sheet 632 reduces the friction between the fixing belt 610 and the pressed member 63. For example, PTFE (Polytetrafluoroethylene) can be used for the sliding sheet 632.
In the sliding sheet 632, an upstream end U and a downstream end L in the transport direction of the paper P are fixed to a base material 630 with a fixing screw 634 via a fixing bracket 633. Here, the sliding sheet 632 should just be fixed by the upstream edge part U at least.

The pressure roll 62 is provided with an elastic layer 620 made of, for example, silicone rubber using a cylindrical roll made of, for example, aluminum or SUS as a base. Moreover, you may further laminate | stack the release layer which consists of a PFA tube.
The pressure roll 62 is disposed so as to be in contact with and away from the fixing belt module 61. When the pressure roller 62 is set so as to press and contact the fixing belt module 61, the direction of the arrow is increased as the fixing belt 610 moves. Rotate to.

FIG. 5 shows a developed partial plan view of the sliding sheet 632. A solid line arrow indicates a direction in which the paper P is conveyed. In FIG. 5, the downstream side is omitted.
In FIG. 5, the sliding sheet 632 has a hole 6320 through which the sliding sheet fixing screw 634 is passed and a notch 6321.
The notch 6321 is formed between the upstream end U in the conveyance direction of the paper P and the nip portion Np, which is a region where the sliding sheet 632 is pressed. Here, the notch 6321 is preferably formed by providing a region N that is not pressurized between the nip portion Np.
In addition, the notch 6321 is preferably provided in the vicinity where the curvature of the corner C on the upstream side and the downstream side of the pad 631 becomes small when the sliding sheet 632 is fixed to the base material 630 shown in FIG.
Further, the direction of the notch 6321 is preferably substantially parallel to the transport direction of the paper P.

Next, a fixing operation in the fixing device 60 of the embodiment will be described.
1 and 2, the sheet P on which the composite toner image (unfixed toner image) has been electrostatically transferred in the secondary transfer region Tr of the image forming apparatus 1 passes through the nip of the fixing device 60 along the fourth conveyance path R4. It is conveyed toward the part Np. The unfixed toner image on the surface of the paper P passing through the nip portion Np is fixed on the paper P mainly by pressure and heat acting on the nip portion Np.

  In the fixing device 60 of the embodiment, the heat acting on the nip portion Np is mainly supplied by the fixing belt 610. The fixing belt 610 includes heat supplied from the halogen heaters 71 and 72 disposed inside the internal heating rolls 612 and 613 through the internal heating rolls 612 and 613, and a halogen disposed inside the pressed member 63. It is heated by the heat supplied from the heater 70. Since heat energy is replenished not only from the internal heating rolls 612 and 613 but also from the pressed member 63, a sufficient amount of heat is secured at the nip portion Np even if the process speed is high.

  FIG. 6 shows a partial schematic diagram when heat is applied to the sliding sheet 632 in the embodiment. In addition, FIG. 7 shows a schematic diagram when heat is applied to the sliding sheet 632C that does not form the notch 6321 as a comparison. In FIG. 6, in order to exaggerate and easily understand the state of deformation when heat is applied to the sliding sheet 632, the fixing bracket 633 portion shown in FIG. 5 is omitted.

In FIG. 7, in the case of the sliding sheet 632 </ b> C that does not form the notch 6321, when heat is applied, as shown in FIG. 4, the upstream end U is fixed by the fixing bracket 633 and the fixing screw 634. The upstream end U is restrained from expanding in the longitudinal direction. On the other hand, at a position away from the upstream end U of the sliding sheet 632C, the sliding sheet 632C expands in the longitudinal direction, for example, has a width indicated by T in the center, and wrinkles W are generated up to the nip portion Np.
When the wrinkle W is generated in the sliding sheet 632C up to the nip portion Np, the fixing belt 610 touches the image at the entrance of the nip portion Np, or the pressure applied to the paper P on which the unfixed toner image is formed at the nip portion Np. Unevenness may occur, resulting in image distortion and defects.

On the other hand, when heat is applied to the sliding sheet 632 of the embodiment, the sliding sheet 632 expands so as to overlap at the notch 6321, and wrinkles at the inlet of the nip portion Np and the nip portion Np can be prevented, so that the image is distorted. , Defects are suppressed.
Further, if the direction of the cut 6321 is substantially parallel to the transport direction of the paper P, wrinkles due to the widening of the cut 6321 when the sliding sheet 632 is pulled in the transport direction are reduced.

(Modification)
In the embodiment, the intervals between the notches 6321 may not be equal.
In FIG. 8, the expansion | deployment partial top view of the sliding sheet | seat 632A of this modification is shown.
In FIG. 8, the interval between the notches 6321 is gradually narrowed from the center to both ends.
Since the displacement of the end portion due to the application of heat is larger than that in the center portion, the sliding sheet 632A between the notches 6321 is narrowed and easily inclined by narrowing the interval between the notches 6321 at both ends. Therefore, the sliding sheet 632A is easily overlapped by the notch 6321, the displacement of the end portion is absorbed, and wrinkles are reduced.

  Further, as shown in the modified example, in addition to the distance between the notches 6321 gradually becoming narrower toward both ends, only the distance between the notches 6321 near both ends is narrower than the distance between the notches 6321 in the center. May be.

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Image forming part, 12 ... Photoconductor drum, 13 ... Charger, 14 ... Exposure device, 15 ... Developing device, 16 ... Cleaner, P ... Paper, 60 ... Fixing device, 61 ... Fixing belt Module, 62 ... Pressure roll, 610 ... Fixing belt, 63 ... Pressurized member, Np ... Nip, 612,613 ... Internal heating roll, 70,71,72 ... Halogen heater, 630 ... Base material, 631 ... Pad C ... upstream and downstream corners, 632, 632A, 632C ... sliding sheet, U ... upstream end, L ... downstream end, 633 ... fixing bracket, 634 ... fixing screw, 620 ... elastic layer, 6320 ... hole, 6321 ... notch, N ... area not pressurized.

Claims (4)

An endless belt that contacts and conveys the recording medium;
A pressure member that contacts and pressurizes the recording medium;
A member to be pressed which is provided inside the belt so as to face the pressure member and receives pressure from the pressure member;
A heating source for heating the belt;
A sheet for reducing friction between the belt and the pressed member,
It said sheet is between the upstream end in the conveying direction of the recording medium to the region where the sheet is pressed, have a plurality of notches toward the downstream,
The fixing device according to claim 1, wherein an interval between the notches at both ends of the sheet is narrower than an interval between the notches at a central portion . The fixing device according to claim 1, wherein the sheet is provided with a non-pressurized region between the notch and the pressed region. The fixing device according to claim 1, wherein the cutting direction is substantially parallel to the transport direction. A fixing device according to any one of claims 1 to 3, an image forming apparatus and forming an image on the recording medium.

Images