JP2007219311A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device which has stable fixing performance even when the amount of slide oil is large. <P>SOLUTION: A plurality of grooves 611d as recessed parts are formed on an outer peripheral surface of a main body part 611a of a fixing roll 611. The grooves 611d are provided at predetermined intervals along the axis of the fixing roll 611. Further, the grooves 611d are formed in the circumferential direction of the main body part 611a which is cylindrically formed over the entire circumference. The recessed parts may be in a shape other than the groove shape. For example, the recessed parts can be formed by partially roughening the external surface of the fixing roll 611 within a range wherein no image defect is generated. Alternatively, parts where the slide oil is evacuated can be formed by giving differences in roughness to the external surface of the fixing roll 611. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixing device used in an image forming apparatus such as a copying machine and a printer, and more particularly to a fixing device including a belt member.

  In a fixing device used in an image forming apparatus, for example, since a toner image is carried on the surface of a recording paper, the toner image becomes an adhesive when the toner image is melted by the heat of the belt member. Adhesive force is applied between the members. For this reason, it is necessary to provide a mechanism for peeling the recording paper from the surface of the belt member.

  As such a mechanism, for example, a mechanism in which a separation claw is disposed in contact with the belt member on the downstream side of the nip portion has been proposed (see Patent Document 1). However, when high-speed fixing is performed with such a mechanism, there is a problem that the leading edge of the paper collides with the peeling claw and the paper is damaged. This problem occurs remarkably when the paper is thin, when the amount of unfixed toner is large, or when oilless toner is used. As a countermeasure against this, there is a method in which the peeling claw is brought into contact with the belt member more strongly. In this case, wear of the belt member surface material by the claw occurs, and the life of the belt member is shortened. Moreover, since the components constituting the peeling claw are indispensable, it is inevitable to increase the size and cost of the apparatus.

  In order to solve such a problem, for example, a mechanism is disclosed in which a fixing member is provided on the inner side of the belt member in the downstream direction of the outlet portion of the nip portion, which is a pressing portion between the fixing roll and the pressure roll. (For example, refer to Patent Document 2). The fixing member sets the curvature of the belt member large and changes the curvature of the belt member to peel off the recording paper. Further, since the paper is peeled without using the peeling claw, damage to the paper can be suppressed.

JP-A-3-133871 Japanese Patent Laid-Open No. 2003-5565

Here, in the mechanism described above, since the fixing member and the inner surface of the belt member slide, sliding oil for sliding is required on the inner surface of the belt member. When the amount of sliding oil is small, the sliding resistance between the fixing member and the inner surface of the belt member increases, and there is a problem that the amount of wear on the inner surface of the belt increases and the life of the belt is shortened. Another problem is that the generated wear powder enters between the fixing roll and the belt member or between the fixing member and the belt member, resulting in uneven pressing force and image distortion. For this reason, it is necessary to attach a certain amount of sliding oil to the inner surface of the belt member.
On the other hand, if the amount of sliding oil is too large, the surface of the fixing roll and the inner surface of the belt member slip, and the drive failure of the belt member (mismatch between the peripheral speed of the fixing roll and the peripheral speed of the belt member) occurs. . As a result, there is a problem that good fixing is hindered.

In addition, the belt member and the roll that stretches the belt member may be incompletely formed, or the parallelism of the rolls that stretch the belt member may not be maintained. In this case, the belt member is not accurately conveyed along a predetermined route, and the belt member meanders in the direction (width direction) perpendicular to the moving direction of the belt member (belt walk), and the belt member is wrinkled. there is a possibility. As a result, there is a problem that wrinkles or the like occur in the paper to be fixed, and stable fixing performance cannot be secured. In order to solve this problem, a technique for preventing meandering of the belt member using a tiltable steering roll disposed on the inner surface side of the belt member has been proposed.
However, if the amount of sliding oil is too large, a slip occurs between the steering roll and the belt member, and there is a possibility that fixing failure due to meandering of the belt member cannot be effectively suppressed.

  Accordingly, the present invention has been made to solve the technical problems as described above, and the object of the present invention is to provide a fixing having stable fixing performance even when the amount of sliding oil is large. To provide an apparatus.

  For this purpose, a fixing device to which the present invention is applied is a fixing device that fixes a toner image carried on a recording material. A belt member to which sliding oil is attached, a pressure member that forms a nip portion where the toner image is fixed between the belt member, an inner circumferential surface of the belt member, A sliding member that slides; and a retracting portion for retracting sliding oil attached to the belt member.

  Here, the nip portion can be formed by pressing the pressing member against the drive roll. Further, the sliding member can be characterized in that the recording member is peeled from the belt member by bending the belt member. Further, the pressing member is pressed against the driving roll to form a nip portion, and the sliding member presses the outer peripheral surface of the belt member against the pressing member in the vicinity of the downstream portion of the nip portion. The recording member can be separated from the belt member by bending the belt member.

  Further, the pressure member is a roll-like member having an elastic layer that is deformed at the nip portion, and at least the outer peripheral surface of the drive roll is formed of a rigid body. Further, the retracting portion may be formed on the outer peripheral surface of the drive roll. The retracting portion may be a concave portion. Furthermore, the retracting portion is a recess formed on the outer peripheral surface of the drive roll, and the recess is a groove formed along the circumferential direction of the drive roll. The groove may be formed over the entire circumference of the drive roll. Further, the grooves may be formed at predetermined intervals in the axial direction of the drive roll.

  From another point of view, the fixing device to which the present invention is applied is a fixing device that fixes a toner image carried on a recording material, and is provided rotatably, and sliding oil is provided on an inner peripheral surface. A belt member is attached, and the belt member is stretched, and a nip portion where the toner image is fixed is formed between the belt member and a steering roll that is tiltably provided to adjust the meandering of the belt member. A pressure member, a sliding member disposed inside the belt member and sliding with the inner peripheral surface of the belt member, and a retracting portion for retracting the sliding oil attached to the belt member.

  Here, the retracting portion may be provided on the outer peripheral surface of the steering roll. Further, the retracting portion may be a groove formed over the entire circumference along the circumferential direction of the steering roll. Further, the present invention may further include a measuring unit that measures the meandering state of the belt member and a tilting unit that tilts the steering roll based on the measurement result of the measuring unit.

  According to the present invention, it is possible to provide a fixing device having stable fixing performance even when the amount of sliding oil is large.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment. The image forming apparatus shown in FIG. 1 is an intermediate transfer type image forming apparatus generally called a tandem type. The image forming apparatus includes a plurality of image forming units 1Y, 1M, 1C, and 1K that form toner images of respective color components by electrophotography. Further, a primary transfer unit 10 that sequentially transfers (primary transfer) the color component toner images formed by the image forming units 1Y, 1M, 1C, and 1K to the intermediate transfer belt 15 is provided. Further, a secondary transfer unit 20 is provided that collectively transfers (secondary transfer) the superimposed toner image transferred onto the intermediate transfer belt 15 onto a sheet as a recording material (recording sheet). Further, a fixing device 60 is provided for fixing the secondary transferred image on the paper. Furthermore, the control part 40 which controls operation | movement of each apparatus (each part) is provided.

  In the present embodiment, the following electrophotographic devices are sequentially arranged in each of the image forming units 1Y, 1M, 1C, and 1K. Around the photosensitive drum 11 rotating in the direction of arrow A, a charger 12 for charging the photosensitive drum 11 is provided. Further, a laser exposure device 13 (the exposure beam is indicated by Bm in the drawing) for writing an electrostatic latent image on the photosensitive drum 11 is provided. Further, a developing device 14 is provided that stores toner of each color component and visualizes the electrostatic latent image on the photosensitive drum 11 with the toner. Further, a primary transfer roll 16 is provided for transferring each color component toner image formed on the photosensitive drum 11 to the intermediate transfer belt 15 by the primary transfer unit 10. Further, a drum cleaner 17 for removing residual toner on the photosensitive drum 11 is provided.

The intermediate transfer belt 15 is circulated and rotated (rotated) at a predetermined speed in the direction of arrow B shown in FIG. 1 by various rolls such as a drive roll 31 driven by a motor (not shown) having excellent constant speed. ing.
The primary transfer unit 10 includes a primary transfer roll 16 that is disposed to face the photosensitive drum 11 with the intermediate transfer belt 15 interposed therebetween. The toner images on the respective photosensitive drums 11 are sequentially electrostatically attracted to the intermediate transfer belt 15 so that the toner images superimposed on the intermediate transfer belt 15 are formed.
The secondary transfer unit 20 includes a secondary transfer roll 22 disposed on the toner image carrying surface side of the intermediate transfer belt 15 and a backup roll 25. The secondary transfer roll 22 is disposed in pressure contact with the backup roll 25 with the intermediate transfer belt 15 interposed therebetween. Further, the secondary transfer roll 22 is grounded and a secondary transfer bias is formed between the secondary transfer roll 22 and the backup roll 25, and the toner image is secondarily transferred onto the sheet conveyed to the secondary transfer unit 20.

  Next, a basic image forming process of the image forming apparatus according to the present embodiment will be described. In the image forming apparatus according to the present embodiment, image data is output from an image reading apparatus (IIT) (not shown) or the like. The image data is subjected to predetermined image processing by an image processing device (IPS) (not shown), converted into color material gradation data of four colors Y, M, C, and K, and output to the laser exposure unit 13. The

  The laser exposure unit 13 irradiates the photosensitive drums 11 of the image forming units 1Y, 1M, 1C, and 1K, for example, with an exposure beam Bm emitted from a semiconductor laser in accordance with the input color material gradation data. Yes. After the surface of each photoconductive drum 11 is charged by the charger 12, the surface is scanned and exposed by the laser exposure unit 13 to form an electrostatic latent image. The formed electrostatic latent images are developed as toner images of Y, M, C, and K colors by the developing devices 14 of the respective image forming units 1Y, 1M, 1C, and 1K. The toner image formed on the photosensitive drum 11 is transferred onto the intermediate transfer belt 15 in the primary transfer unit 10 where each photosensitive drum 11 and the intermediate transfer belt 15 abut.

  After the toner images are sequentially primary transferred onto the surface of the intermediate transfer belt 15, the intermediate transfer belt 15 moves and the toner image is conveyed to the secondary transfer unit 20. In the secondary transfer unit 20, the secondary transfer roll 22 is pressed against the backup roll 25 via the intermediate transfer belt 15. At this time, the paper K transported by the transport roll 52 and the like at the same timing is sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 22. The unfixed toner image carried on the intermediate transfer belt 15 is electrostatically transferred collectively onto the paper in the secondary transfer unit 20. Thereafter, the sheet on which the toner image has been electrostatically transferred is conveyed to a conveyance belt 55 provided downstream of the secondary transfer roll 22 in the sheet conveyance direction. The conveyance belt 55 includes two support rolls and a belt stretched around the support rolls, and stably conveys the sheet to the fixing device 60 at an optimum conveyance speed.

Next, the fixing device 60 to which the exemplary embodiment is applied will be described.
FIG. 2 is a cross-sectional view illustrating a schematic configuration of the fixing device 60 according to the embodiment. The fixing device 60 includes a fixing belt module 61 as a main part. The fixing device 60 includes a pressure roll 62 as an example of a pressure member disposed in pressure contact with the fixing belt module 61.

  The fixing belt module 61 includes a fixing belt 610 as an example of a belt member, a fixing roll 611 as a driving roll that rotates while fixing the fixing belt 610, and a fixing belt 610 that extends from the inside. And a steering roll 612 for adjusting the meandering of 610. The fixing belt module 61 stretches the fixing belt 610 from the outside, and stabilizes the posture of the fixing belt 610 between the heating roll 613 that heats the fixing belt 610 and the fixing roll 611 and the steering roll 612. A stable roll 614. Further, the fixing belt module 61 is an example of a sliding member disposed in the vicinity of the fixing roll 611 in the downstream area in the nip portion N where the fixing belt module 61 and the pressure roll 62 are in pressure contact with each other. The peeling pad 64 is provided. The fixing belt module 61 includes an idler roll 615 that stretches the fixing belt 610 on the downstream side of the nip portion N. Further, the fixing belt module 61 is a sensor 65 as a measuring unit that measures the meandering state of the fixing belt 610, a drive source M that rotationally drives the fixing roll 611, and a position as a tilting unit that adjusts the inclination of the steering roll 612. And an adjustment unit 63.

  The fixing belt 610 is a flexible endless belt. Then, a base layer made of polyimide or the like having a thickness of about 80 μm, an elastic layer made of silicone rubber or the like having a thickness of about 200 μm laminated on the surface side (outer peripheral surface side) of the base layer, and further on the elastic body layer It is comprised with the mold release layer which consists of about 30 micrometers PFA etc. which were coat | covered. The fixing belt 610 moves (rotates) in the arrow D direction as the fixing roll 611 rotates.

  The fixing roll 611 is formed in a cylindrical shape with a rigid body such as metal. The fixing roll 611 rotates in the direction of arrow C in response to the driving force from the driving source M. In addition, a heater 616a is disposed inside the fixing roll 611 as a heating unit. In addition, the steering roll 612 is a cylindrical roll, and a heater (not shown) is provided as a heating unit therein. In addition, spring members (not shown) that press the fixing belt 610 outward are disposed at both ends of the steering roll 612 to apply tension to the entire fixing belt 610. Accordingly, the steering roll 612 has a function of stretching the fixing belt 610 and a function of heating the fixing belt 610 from the inner peripheral surface side. Although details will be described later, the steering roll 612 further has a function of adjusting the meandering of the fixing belt 610.

  The heating roll 613 is a cylindrical roll, and a heater 616c serving as a heating unit is disposed therein. For this reason, the heating roll 613 has both a function of stretching the fixing belt 610 and a function of heating the fixing belt 610 from the outer peripheral surface side. Therefore, in this embodiment, a configuration in which the fixing belt 610 is heated by the fixing roll 611, the steering roll 612, and the heating roll 613 is employed.

Further, the pressure roll 62 uses a cylindrical roll 621 as a base. And the elastic layer 622 and the release layer 623 are laminated | stacked in order from the base | substrate side, and the soft roll is comprised. The pressure roll 62 is installed so as to be pressed against the fixing belt module 61. The elastic layer 622 and the release layer 623 are deformed in a concave shape in the direction of the cylindrical roll 621 by the pressure on the fixing belt module 61, more specifically, the pressure on the fixing roll 611. Part is formed. As the fixing roll 611 of the fixing belt module 61 rotates in the direction of arrow C, the pressure roll 62 rotates in the direction of arrow E following the fixing roll 611.
The position adjusting unit 63 includes a motor 63a as a driving source, a cam member 63b rotated by the motor 63a, and a rod having one end locked to the cam member 63b and the other end locked to the steering row 612. And a member 63c.

  The sheet on which the toner image has been transferred is sandwiched between the pressure roll 62 and the fixing belt 610 and introduced (passed through) into the nip N portion. In the nip portion N, the paper is heated and pressed, and the toner image is fixed on the paper. The fixing belt 610 located in the nip portion N reaches the peeling pad 64 after passing through the nip portion N, and rotates following the side surface of the peeling pad 64. Accordingly, the advancing direction of the fixing belt 610 is rapidly changed so as to be bent in the direction of the idler roll 615 by the peeling pad 64. For this reason, the sheet cannot follow the change in the advancing direction of the fixing belt 610 when it comes out of the press contact portion formed by the peeling pad 64 and the pressure roll 62.

  As a result, the sheet is peeled from the fixing belt 610 by the so-called “koshi”. In this manner, curvature separation with respect to the sheet is stably performed at the exit of the nip portion N. The sheet separated from the fixing belt 610 is guided in the traveling direction by a peeling guide plate (not shown) disposed on the downstream side of the nip portion N. By the way, the peeling pad 64 and the fixing belt 610 are configured to slide as described above. Therefore, in this embodiment, sliding oil such as silicone sliding oil is attached to the inner peripheral surface of the fixing belt 610 for the reason of reducing the sliding resistance between the peeling pad 64 and the fixing belt 610.

Further, the fixing device 60 will be described in detail.
FIG. 3 is a plan view of the fixing device 60. As shown in the figure, the fixing roll 611 includes a main body portion 611a that stretches the fixing belt 610, a support portion 611b that is provided on both sides of the main body portion 611a and supports the main body portion 611a, and one support portion 611b. And a gear portion 611c provided on the head. The fixing roll 611 is rotatably provided by supporting the supporting portion 611b via a bearing or the like on a housing or the like (not shown). A driving source M such as a motor is connected to the gear portion 611c, and the driving force of the driving source M is transmitted to the fixing roll 611 via the gear portion 611c. As a result, the fixing roll 611 is driven to rotate. As the fixing roll 611 is rotated, the fixing belt 610 stretched around the fixing roll 611 is also rotated.

  The steering roll 612 includes a main body portion 612a that stretches the fixing belt 610, and support portions 612c arranged on both sides of the main body portion 612a. One support portion 612c is provided with a position adjusting portion 63, and an end portion of the other support portion 612c is provided with a bearing portion 612b. One support portion 612c is movably provided by the position adjustment portion 63, and the other support portion 612c is fixed to a housing or the like (not shown) via a bearing portion 612b. As a result of the one support portion 612c being movably provided by the position adjustment portion 63, the tilt of the steering roll 612 can be adjusted.

  Here, the forming of the fixing belt 610 and the heating roll 613 for stretching the fixing belt 610 is incomplete, or the parallelism of the heating roll 613 and the idler roll 615 for stretching the fixing belt 610 is maintained. There may be no. In this case, the fixing belt 610 is not accurately conveyed along a predetermined path, and the fixing belt 610 snakes in a direction perpendicular to the moving direction (the width direction of the fixing belt 610), and the belt member may be wrinkled. There is sex. As a result, the paper to be fixed is wrinkled, and there is a problem that stable fixing performance cannot be secured. In order to solve this problem, in this embodiment, meandering of the fixing belt 610 is suppressed by using a tiltable steering roll 612 disposed inside the fixing belt 610.

Here, the amount of meandering of the fixing belt 610 is measured by the sensor 65.
As the sensor 65, for example, a mechanical sensor that outputs a signal when an end portion in the width direction of the fixing belt 610 contacts, various optical sensors, or the like can be used. The measured meandering amount is sent to the control unit 40 shown in FIG. The control unit 40 controls the position adjustment unit 63 based on the output from the sensor 65. As described above, the position adjusting unit 63 includes the motor 63a, the cam member 63b rotated by the motor 63a, one end locked to the cam member 63b, and the other end locked to the support portion 612c of the steering roll 612. Rod member 63c.

  The control unit 40 drives the motor 63a based on the meandering amount of the fixing belt 610 from the sensor 65, and rotates the cam member 63b at a predetermined angle. As the cam member 63b rotates, the rod member 63c locked to the cam member 63b moves in a direction toward and away from the steering roll 612, thereby adjusting the inclination of the steering roll 612. As the tilt of the steering roll 612 changes, the tension in the width direction of the fixing belt 610 applied to the fixing belt 610 also changes. Due to the change in angle and tension, the fixing belt 610 moves in the axial direction of the steering roll 612. Even if the fixing belt 610 meanders in this way, the meandering can be adjusted.

  Incidentally, as described above, the fixing belt 610 is configured to rotate with the rotation of the fixing roll 611, and sliding oil adheres to the inner peripheral surface of the fixing belt 610. The sliding oil is supplied for reasons such as reducing the sliding resistance between the peeling pad 64 and the fixing belt 610. If the amount is too large, the outer peripheral surface of the main body 611a and the fixing belt 610 are supplied. There is a possibility that slip occurs between the inner peripheral surface and the driving force from the fixing roll 611 is not sufficiently transmitted to the fixing belt 610. That is, there is a possibility that a driving failure of the fixing belt 610 (inconsistency between the peripheral speed of the fixing roll 611 and the peripheral speed of the fixing belt 610) may occur. When this drive failure occurs, good fixing is hindered. In addition, when the amount of sliding oil supplied is too large, slip occurs between the main body 612a of the steering roll 612 and the inner peripheral surface of the fixing belt 610, and the adjustment of the meandering of the fixing belt 610 by the steering roll 612 is appropriately performed. There are cases where this is not possible. Therefore, in the present embodiment, as described later, the fixing roll 611 and the steering roll 612 are provided with a recess as an example of a retracting section for retracting the sliding oil.

FIG. 4 is an explanatory view showing details of the fixing roll 611.
A groove 611d as a recess is formed on the outer peripheral surface of the main body 611a of the fixing roll 611 shown in FIG. A plurality of grooves 611d are provided at predetermined intervals in the axial direction of the fixing roll 611. Moreover, in this embodiment, the groove | channel 611d is formed over the perimeter along the circumferential direction of the main-body part 611a formed in the cylindrical shape. By forming the groove 611d along the circumferential direction of the main body 611a, meandering of the fixing belt 610 that may be caused by the groove 611d can be suppressed. Moreover, the workability of the groove 611d can be improved by forming the groove 611d along the circumferential direction and over the entire circumference. Such a groove 611d can also be formed on the inner peripheral surface of the fixing belt 610. Moreover, in this embodiment, although formed in groove shape, it can also be set as shapes other than groove shape. For example, the concave portion can be formed by partially roughening the outer surface of the fixing roll 611 within a range where no image defect occurs. In addition, a portion for retracting the sliding oil can be formed by making a difference in the roughness of the outer surface of the fixing roll 611. Next, the groove 611d will be described in more detail.

  FIG. 5 is an explanatory diagram showing a state in the vicinity of the outer peripheral surface of the main body 611a in the nip N (see FIG. 2). In the nip portion N, the pressure roll 62 is disposed in pressure contact with the fixing roll 611 via the fixing belt 610 as described above. This figure shows a state in which a sheet is passed between the fixing belt 610 and the pressure roll 62 at the pressure contact portion. Each groove 611d has a predetermined depth D and a predetermined width W, and is formed in a substantially rectangular shape. Each groove 611d is arranged at a predetermined interval P from another adjacent groove 611d.

  Here, the depth D of the groove 611d is not particularly limited as long as it is equal to or larger than the size capable of taking in the sliding oil and smaller than the size at which the strength of the fixing roll 611 is reduced. On the other hand, when the width W of the groove 611d is large, the pressing force to the paper in the groove 611d is reduced, or the heat supplied from the fixing roll 611 to the fixing belt 610 is not uniform. As a result, image defects and gloss unevenness occur. For this reason, it is desirable that the width of the groove 611d is not more than a predetermined value. This value is strictly defined because it depends on the rigidity of the base layer of the fixing belt 610 (how much the fixing belt 610 bends in the groove 611d), the pressing load from the pressure roll 62, and other fixing conditions. It is difficult. However, in the experiments conducted by the inventors, which will be described later, good results were obtained with a value of 1 mm or less. Note that the width of the groove 611d is not necessarily constant, and may be a shape in which the width varies depending on the location.

  On the other hand, with respect to the interval P between the grooves 611d, if the interval P is too large, the sliding oil cannot escape into the groove 611d, which may cause slip and drive failure. For this reason, it is preferable that it is below a predetermined magnitude | size. As for the predetermined size, as with the width of the groove 611d, it is difficult to strictly define, but in the experiments by the inventors described later, good results are obtained in the vicinity of 20 mm. In addition, although it is the shape of the groove | channel 611d, although it is set as the rectangular shape in this embodiment, it can also be set as a U shape or V shape, for example. Further, the material of the surface of the main body 611a is not particularly limited, and for example, a material usually used for a fixing member such as metal, fluororesin, resin such as PFA or polyimide, rubber, or the like is appropriately used. Can do.

  By providing the groove 611d, it is possible to allow excess sliding oil located between the outer peripheral surface of the main body 611a of the fixing roll 611 and the inner peripheral surface of the fixing belt 610 to escape into the groove 611d. . As a result, the outer peripheral surface of the main body 611a and the inner peripheral surface of the fixing belt 610 can be brought into close contact with each other. For this reason, slip is prevented, and the driving force can be appropriately transmitted from the fixing roll 611 to the fixing belt 610. As a result, it is possible to realize reliable driving of the fixing belt 610 while maintaining a good sliding state between the peeling pad 64 and the fixing belt 610. Furthermore, in this embodiment, since the peeling pad 64 is used, it is possible to ensure the paper peeling performance in high-speed fixing.

  Conventionally, if too much sliding oil is supplied, slip may occur between the fixing roll 611 and the fixing belt 610, so that it is difficult to supply much sliding oil. If a large amount of sliding oil is not supplied, slipping can be prevented, but the belt is likely to be worn, and it is difficult to press the peeling pad 64 against the pressure roll 62 with a large force. In the present embodiment, since a configuration that prevents slip between the fixing belt 610 and the fixing roll 611 is employed, a sufficient amount of sliding oil can be supplied to the inner circumferential surface of the belt. As a result, wear of the fixing belt 610 can be improved, and the life of the fixing belt 610 can be extended. Furthermore, since the sliding state between the fixing belt 610 and the peeling pad 64 can be ensured in a good state, the pressing force of the peeling pad 64 to the pressure roll 62 can be set large. As a result, the image quality of the fixed image can be improved and the fixing speed can be increased.

Here, an experiment was conducted on the driving performance of the fixing belt 610 when the sliding oil was actually attached and the width W and the interval P of the groove 611d were changed.
FIG. 6 shows experimental results such as the driving performance of the fixing belt 610 when the width W and the interval P of the groove 611d are appropriately changed. More specifically, a fixing operation was actually performed using the fixing device 60 having the configuration shown in FIG. 2, and the driving performance of the fixing belt 610 and the presence or absence of image defects were evaluated. In FIG. 6, “A” indicates that a drive failure (a speed difference between the fixing roll 611 and the fixing belt 610 has occurred) has occurred, “B” indicates that an image defect (gross unevenness) has occurred, and “◯”. Indicates that these defects were not found.

Detailed evaluation conditions are as follows.
・ Sliding oil: Silicone sliding oil ・ Amount of sliding oil: 10 ⁻⁶ [m ³ ] (1 [cc])
Process speed (moving speed of fixing belt 610): 264 [mm / sec]
-Diameter of fixing belt 610: φ168 [mm]
Configuration of fixing belt 610: Base layer: polyimide substrate (thickness: 80 [μm]), elastic layer: silicone rubber (thickness: 200 [μm]), release (surface) layer: PFA (thickness) : 30 [μm])
-Temperature of fixing belt 610: 160 [° C.]
-Diameter of fixing roll 611: φ100 [mm]
-Material of fixing roll 611: Aluminum-Diameter of pressure roll 62: φ100 [mm]
Structure of the pressure roll 62: elastic layer (intermediate layer) 622 ... Si rubber (thickness: 10 [mm]), release layer (surface layer) 623 ... PFA (thickness: 100 [μm])
・ Peeling pad 64 material: Stainless steel (only the sliding surface with the fixing belt 610 is coated with fluororesin)
Fixing Nip load (pressing force of the pressure roll 62 to the fixing roll 611): 2940 [N] (300 [kgf])
Pressing load of the peeling pad 64 (pressing force of the peeling pad 64 to the pressure roll 62): 392 [N] (40 [kgf])
Depth D of groove 611d: 0.5 [mm] when groove width W is 0.5 [mm] and 1 [mm], 1 [mm] when groove width W is 2 [mm]
・ Paper: OK Topcoat 127.9 [gsm]

Here, the experimental results will be described.
When the width W of the groove 611d is 0 mm, that is, when the groove 611d is not provided, it can be seen that a drive failure has occurred. On the other hand, when the groove 611d is provided, although it depends on the width W of the groove 611d and the like, no trouble occurs, and it can be seen that the formation of the groove 611d is effective in suppressing drive failure.
Next, when the width W of the groove 611d was changed, it was found that an image defect caused by a decrease in pressing force occurred when the width W was 2 mm. However, when the width W was 1 mm and 0.5 mm, No image defect occurred. Therefore, it can be seen that the width W of the groove 611d is preferably 1 mm or less (desirably 0.5 to 1 mm).

  On the other hand, when the interval P of the groove 611d is changed, it can be seen that a drive failure occurs under the condition that the interval P is large. Specifically, when the interval P is 100 mm, a driving failure occurred in the entire width W of the groove 611d. When the interval P is 50 mm, a drive failure occurs under some conditions (a condition where the width W of the groove 611d is 0.5 mm), and another condition (the width W of the groove 611d is 1 mm). (Under the condition) no failure occurred. For this reason, it is preferable that the space | interval P of the groove | channel 611d is 50 mm or less. When the interval P between the grooves 611d is 15 to 30 mm, no drive failure occurs. Therefore, it is more preferable to set the interval P between the grooves 611d to 15 to 30 mm. On the other hand, in the condition where the interval P of the groove 611d is small, specifically, when the interval P is 5 mm, a drive failure occurs. This drive failure is not caused by sliding oil, but is considered to be caused by slip due to a decrease in the contact area between the fixing belt 610 and the fixing roll 611 due to the formation of a large number of grooves 611d.

Next, the recessed part provided in the steering roll 612 is demonstrated.
FIG. 7 is an explanatory view showing details of the steering roll 612. As shown in the figure, the steering roll 612 also has a groove 612d as a recess. The groove 612d in the present embodiment has substantially the same shape and arrangement as the groove 611d provided in the main body 611a of the fixing roll 611 shown in FIG. That is, a plurality of grooves 612d are provided at predetermined intervals in the axial direction of the steering roll 612. Further, the groove 612d is formed along the circumferential direction of the main body 612a of the steering roll 612 formed in a cylindrical shape and over the entire circumference. Furthermore, each groove 612d has a predetermined depth and a predetermined width and is formed in a substantially rectangular shape. If the width W of the groove 611d formed on the fixing roll 611 is increased to a predetermined size or more, there is a problem that image defects and gloss unevenness due to a decrease in pressing force occur as described above. . However, in the steering roll 612, image defects and gloss unevenness due to a decrease in pressing force do not occur. Therefore, the width W (see FIG. 5) of the groove 612d of the steering roll 612 can be set larger than the width W of the groove 611d of the fixing roll 611.

  As described above, the steering roll 612 functions to suppress the meandering of the fixing belt 610. However, if the sliding oil is excessively supplied to the inner peripheral surface of the fixing belt 610, there is a possibility that slip occurs between the steering roll 612 and the fixing belt 610. As a result, there arises a problem that the meandering of the fixing belt 610 cannot be appropriately suppressed. In the present embodiment, a groove 612d is formed in the main body 612a of the steering roll 612, and excess sliding oil can be released to the groove 612d. For this reason, slippage between the steering roll 612 and the fixing belt 610 due to sliding oil can be suppressed. As a result, it is possible to appropriately adjust the meandering of the fixing belt 610 using the steering roll 612.

Next, a modified example of the recess will be described.
FIG. 8 is an explanatory view showing the fixing roll 611 in which a concave portion is formed.
FIG. 8A shows a case where a groove 611d as a recess is formed on the outer peripheral surface of the main body 611a. In the fixing roll 611 shown in FIG. 4, as described above, the groove 611d is continuously formed on the outer peripheral surface of the main body 611a, and the groove 611d is formed along the circumferential direction and over the entire periphery of the main body 611a. On the other hand, the groove 611d in the present embodiment is the same in that it is formed along the circumferential direction, but is not formed over the entire circumference, and is formed discontinuously in the circumferential direction. Thus, the groove 611d can be formed discontinuously.

  FIG. 8B shows a form in which concave portions are formed in the shape of dots on the outer peripheral surface of the main body portion 611a. Specifically, each recess is formed as a dimple-shaped round recess 611e. The recesses 611e are arranged at predetermined intervals in the circumferential direction of the main body 611a, and are arranged at predetermined intervals in the axial direction of the fixing roll 611. Excess sliding oil escapes into the indentation 611e, so that slip between the fixing roll 611 and the fixing belt 610 is suppressed. As described above, the concave portion can be formed other than the groove shape. Although the above shows an example in which the concave portion is formed in the fixing roll 611, it can be applied to the steering roll 612.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment. 1 is a cross-sectional view illustrating a schematic configuration of a fixing device according to an embodiment. 2 is a plan view of the fixing device. FIG. FIG. 4 is an explanatory diagram showing details of a fixing roll. It is explanatory drawing which showed the state of the outer peripheral surface of the main-body part in a nip part. 6 shows experimental results such as the driving performance of the fixing belt when the width and interval of the grooves are appropriately changed. It is explanatory drawing which showed the detail of the steering roll. FIG. 6 is an explanatory view showing a fixing roll having a recess.

Explanation of symbols

DESCRIPTION OF SYMBOLS 60 ... Fixing device, 62 ... Pressure roll, 63 ... Position adjustment part, 64 ... Peeling pad, 65 ... Sensor, 610 ... Fixing belt, 611 ... Fixing roll, 611d ... Groove, 611e ... Recess, 612 ... Steering roll, 622 ... elastic layer, N ... nip

Claims (14)

A fixing device for fixing a toner image carried on a recording material,
A driving roll for rotational driving;
A belt member stretched around the drive roll and attached with sliding oil on the inner peripheral surface;
A pressure member that forms a nip portion between which the toner image is fixed with the belt member;
A sliding member disposed inside the belt member and sliding with an inner peripheral surface of the belt member;
A retracting portion for retracting sliding oil attached to the belt member;
Including a fixing device.   The fixing device according to claim 1, wherein the nip portion is formed by pressing the pressure member against the driving roll.   The fixing device according to claim 1, wherein the sliding member bends the belt member and peels the recording material from the belt member. The pressure member is pressed against the drive roll to form the nip portion,
The sliding member presses the outer peripheral surface of the belt member against the pressure member in the vicinity of the downstream portion of the nip portion, and bends the belt member to peel the recording material from the belt member. The fixing device according to claim 1.   5. The fixing according to claim 4, wherein the pressure member is a roll-like member having an elastic layer that is deformed in the nip portion, and at least an outer peripheral surface of the drive roll is formed of a rigid body. apparatus.   The fixing device according to claim 1, wherein the retracting portion is formed on an outer peripheral surface of the drive roll.   The fixing device according to claim 6, wherein the retracting portion is a concave portion. The retracting portion is a recess formed on the outer peripheral surface of the drive roll,
The fixing device according to claim 1, wherein the recess is a groove formed along a circumferential direction of the drive roll.   The fixing device according to claim 8, wherein the groove is formed over the entire circumference of the drive roll.   The fixing device according to claim 8, wherein the grooves are formed at predetermined intervals in the axial direction of the drive roll. A fixing device for fixing a toner image carried on a recording material,
A belt member that is rotatably provided and has sliding oil attached to the inner peripheral surface;
A steering roll provided to be able to tilt and stretch the belt member and adjust the meandering of the belt member;
A pressure member that forms a nip portion between which the toner image is fixed with the belt member;
A sliding member disposed inside the belt member and sliding with an inner peripheral surface of the belt member;
A retracting portion for retracting sliding oil attached to the belt member;
Including a fixing device.   The fixing device according to claim 11, wherein the retracting portion is provided on an outer peripheral surface of the steering roll.   The fixing device according to claim 12, wherein the retracting portion is a groove formed over the entire circumference along a circumferential direction of the steering roll.   12. The fixing device according to claim 11, further comprising: a measuring unit that measures a meandering state of the belt member; and a tilting unit that tilts the steering roll based on a measurement result by the measuring unit.

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