JP7424022B2 - Fixing device and image forming device - Google Patents

Description

The present invention relates to a fixing device and an image forming apparatus used in image forming apparatuses such as copying machines, printers, and facsimile machines.

As a fixing device, as shown in FIG. 9, a fixing pad 102 is placed inside the fixing belt 101 with the fixing belt 101 in between, and a pressure roller 103 is placed outside the fixing belt 101 in pressure contact with each other, so that the paper P can pass therethrough. 2. Description of the Related Art A fixing device in which a fixing nip N for fixing a toner image on a sheet of paper P is formed is conventionally known.

In such a fixing device, the fixing pad 102 is fixed, and a large frictional force acts between the fixing belt 101 and the fixing pad 102 when the fixing belt 101 rotates in the direction of arrow R2. Therefore, a sliding sheet 104 may be interposed between the fixing belt 101 and the fixing pad 102 in order to reduce the frictional force. The sliding sheet 104 is generally held in a fixed state at its end by a sliding sheet holding member (not shown) on the upstream side of the fixing nip N. Further, in order to further reduce the frictional force between the fixing belt 101 and the sliding sheet 104, a lubricant may be interposed between the fixing belt 101 and the sliding sheet 104.

By the way, the meandering of the fixing belt 101 may cause the fixing belt 101 to move in the rotation axis direction (the width direction of the fixing belt). This movement of the fixing belt 101 generates a frictional force in the direction of the rotating shaft between the fixing belt 101 and the sliding sheet 104, and this frictional force may deform the sliding sheet 104 into an uneven or wavy shape in the paper width direction. When such a deformation occurs in the sliding sheet 104, the pressure distribution on the paper P passing through the fixing nip N becomes uneven, resulting in uneven heating. There is a problem in that lubricant pools occur, causing unevenness in the lubricant and causing image noise.

Patent Document 1 discloses that in order to suppress wrinkles due to thermal expansion of the sliding sheet at the entrance of the nip portion, tension is applied to the sliding sheet between one fixed end of the sliding sheet and the sliding surface. A fusing device having a tensioning member is disclosed.

Patent Document 2 discloses that even if the sliding sheet is heated and stretched in the fixing device, in order to suppress the occurrence of wrinkles in the sliding sheet, the elasticity limit point at the fixing temperature or below is determined depending on the material of the sliding sheet. A fixing device is disclosed in which a spring member is provided within a range in which wrinkles do not occur due to elongation of the sliding sheet at the fixing temperature.

Japanese Patent Application Publication No. 2014-145858 Japanese Patent Application Publication No. 2013-214039

However, both Patent Documents 1 and 2 disclose techniques for suppressing wrinkles caused by thermal expansion of a sliding sheet, and they do not solve the problem described above, that is, when the fixing belt 101 moves in the direction of the rotation axis. In some cases, the sliding sheet 104 is deformed, which causes image noise, and no solution has been provided.

The present invention has been made in view of the above technical background, and provides a fixing device and a fixing device capable of suppressing the deformation of the sliding sheet when the fixing belt moves in the direction of the rotation axis, thereby suppressing the generation of image noise. The purpose of the present invention is to provide an image forming apparatus.

The above objective is achieved by the following means.
(1) A rotating fixing belt, a pressure roller that comes into pressure contact with the fixing belt from the outside to form a fixing nip, and a sliding sheet that is arranged to come into contact with the inner surface of the fixing belt and slide on the fixing belt. and a fixing pad which is pressed against the fixing belt with the sliding sheet in between and is pressed against the pressure roller, and the sliding sheet is moved into the fixing pad according to the movement of the fixing belt in the direction of the rotation axis. A fixing device comprising: a variable mechanism for moving a belt in the direction of its rotational axis .
(2) A rotating fixing belt, a pressure roller that comes into pressure contact with the fixing belt from the outside to form a fixing nip, and a sliding sheet that is arranged to come into contact with the inner surface of the fixing belt and slide on the fixing belt. and a fixing pad that is pressed against the fixing belt with the sliding sheet in between and is pressed against the pressure roller, and the sliding sheet is moved in accordance with the movement of the fixing belt in the rotation axis direction. a variable mechanism, the variable mechanism includes an axially moving member that is disposed upstream of the fixing nip and moves in conjunction with the movement of the fixing belt in the rotational axis direction, and the sliding sheet A fixing device that moves in conjunction with the movement of an axially moving member.
(3) A rotating fixing belt, a pressure roller that presses against the fixing belt from outside to form a fixing nip, and a sliding sheet that is arranged to contact the inner surface of the fixing belt and slide on the fixing belt. and a fixing pad that is pressed against the fixing belt with the sliding sheet in between and is pressed against the pressure roller, and the sliding sheet is moved in accordance with the movement of the fixing belt in the rotation axis direction. a variable mechanism; the variable mechanism includes a detection means for detecting the amount of movement of the fixing belt in a rotational axis direction; and a detection means for changing a contact state with the fixing belt based on a detection result of the detection means. A fixing device comprising: a steering means for moving the fixing belt in the direction of the rotation axis, and the sliding sheet moves in accordance with the movement of the fixing belt in the direction of the rotation axis by the steering means.
( 4 ) The variable mechanism includes an axially moving member that is disposed on the upstream side of the fixing nip and moves in conjunction with the movement of the fixing belt in the rotational axis direction, and the sliding sheet is connected to the axially moving member. 2. The fixing device according to item 1, which moves in conjunction with the movement of the fixing device.
( 5 ) The axially moving member is a roller whose peripheral surface is in pressure contact with the inner circumferential surface of the fixing belt, and configured to move in the direction of the rotation axis in conjunction with the fixing belt due to frictional force with the fixing belt. The sliding sheet holding member is a holding member that holds both ends of the roller-like member, and the sliding sheet holding member is a holding member that holds both ends of the roller-like member. 5. The fixing device according to item 2 or 4, which is connected to each other.
( 6 ) The variable mechanism includes a detection means for detecting the amount of movement of the fixing belt in the rotational axis direction, and changes a contact state with the fixing belt based on the detection result of the detection means to rotate the fixing belt. 2. The fixing device according to item 1, further comprising: a steering means for moving the fixing belt in the axial direction, and the sliding sheet moves in accordance with the movement of the fixing belt in the rotation axis direction by the steering means.
( 7 ) The fixing device according to any one of items 1 to 6 , wherein the amount of movement of the fixing belt is greater than the amount of movement of the sliding sheet.
( 8 ) The steering means is configured to include a heating roller that supports the inner circumferential surface of the fixing belt and stretches the fixing belt , and also heats the fixing belt. The fixing device according to any one of the preceding paragraphs 7 which cites .
( 9 ) The fixing device according to any one of items 1 , 3, 6, and 8, wherein the variable mechanism moves the sliding sheet independently of movement of the fixing belt.
( 10 ) An image forming apparatus comprising an image forming means and the fixing device according to any one of items 1 to 9 above, which fixes an image formed by the image forming means and transferred to a sheet of paper.

According to the invention described in the preceding item (1), the sliding sheet interposed between the fixing belt and the fixing pad is moved in the direction of the rotation axis of the fixing belt by the variable mechanism according to the movement in the rotation axis direction of the fixing belt. Since it is moved, when the fixing belt moves in the direction of the rotation axis, the sliding sheet also moves. Therefore, even if the fixing belt moves in the direction of the rotation axis, the sliding sheet can also be moved in the direction of the rotation axis of the fixing belt so that a large frictional force is not generated between it and the fixing belt. It is possible to suppress deformation of the paper into an uneven or wavy shape in the paper width direction. As a result, a fixing device is obtained in which image noise generated due to deformation of the sliding sheet is suppressed.

According to the invention described in the preceding item ( 4 ), the variable mechanism includes an axially moving member that is disposed upstream of the fixing nip and moves in conjunction with the movement of the fixing belt in the rotational axis direction, and the sliding sheet is Since it moves in conjunction with the movement of the axially moving member, it has a relatively simple configuration and can reliably move the sliding sheet in the same direction as the fixing belt in accordance with the movement of the fixing belt in the rotation axis direction. .

According to the invention described in the preceding paragraph ( 5 ), when the axially movable member made of a roller-like member moves in conjunction with the movement of the fixing belt in the rotational axis direction, the axially moving member made of a roller-like member is connected to a holding member that holds both ends of the roller-like member. Since the sliding sheet holding member also moves in the same movement direction, the sliding sheet can be moved in accordance with the movement of the fixing belt in the rotation axis direction.

According to the invention described in the preceding item ( 6 ), the contact state with the fixing belt is changed based on the detection result of the detection means that detects the amount of movement of the fixing belt in the rotation axis direction, and the fixing belt is moved in the rotation axis direction. The sliding sheet is equipped with a steering means for moving, and the sliding sheet is moved in accordance with the movement of the fixing belt in the direction of the rotational axis by the steering means, so the sliding sheet can be moved with high accuracy in accordance with the movement of the fixing belt in the direction of the rotational axis. can be done.

According to the invention described in the previous item ( 7 ), since the amount of movement of the fixing belt is larger than the amount of movement of the sliding sheet, the difference in the amount of movement causes a moderate gap between the fixing belt and the sliding sheet in the direction of the rotation axis. Frictional force is generated, and deformation of the sliding sheet can be effectively eliminated.

According to the invention described in the preceding item ( 8 ), the inner peripheral surface of the fixing belt is supported and the fixing belt is stretched, and the fixing belt is stretched by changing the contact state with the fixing belt by the heating roller that heats the fixing belt. When the slider moves in the direction of the rotation axis, the sliding sheet can be moved accordingly.

According to the invention described in the preceding item ( 9 ), since the amount of movement of the sliding sheet can be adjusted independently of the movement of the fixing belt, the degree of freedom in adjustment is increased.

According to the invention described in the preceding item ( 10 ), even if the fixing belt of the fixing device moves in the direction of the rotation axis, deformation of the sliding sheet can be suppressed, and deformation of the sliding sheet due to deformation of the sliding sheet can be suppressed. This results in an image forming apparatus that suppresses generated image noise.

FIG. 2 is a diagram illustrating the configuration of a fixing device in an image forming apparatus according to an embodiment of the present invention, and is a front view seen from one side in the rotation axis direction of the fixing belt (width direction of the fixing belt). FIG. 3 is a perspective view showing an example of an axially moving member. FIG. 7 is a perspective view showing another example of the axially moving member. FIG. 2 is a diagram showing the configuration of a fixing device in an image forming apparatus according to another embodiment of the present invention, and is a front view when viewed from the same direction as FIG. 1. FIG. It is a perspective view for explaining a steering means. FIG. 2 is a diagram showing the configuration of a fixing device in an image forming apparatus according to still another embodiment of the present invention, and is a front view when viewed from the same direction as FIG. 1. FIG. FIG. 2 is a diagram showing the configuration of a fixing device in an image forming apparatus according to still another embodiment of the present invention, and is a front view when viewed from the same direction as FIG. 1. FIG. FIG. 2 is a diagram showing the configuration of a fixing device in an image forming apparatus according to still another embodiment of the present invention, and is a front view when viewed from the same direction as FIG. 1. FIG. FIG. 2 is an enlarged view of a main part of a fixing device, and is a diagram for explaining a problem of the prior art.

Embodiments of the present invention will be described below based on the drawings.
[First embodiment]
FIG. 1 shows the configuration of a fixing device in an image forming apparatus according to an embodiment of the present invention, and is a front view seen from one side in the rotation axis direction of the fixing belt (width direction of the fixing belt).

The image forming apparatus 1 includes a fixing device 2 and an image forming section 3, and conveys a sheet of paper onto which a toner image formed by the image forming section 3 has been transferred along a paper conveyance path 4, and heats the sheet by passing it through the fixing device 2. The structure is such that pressure is applied to fix the toner image on the paper.

The fixing device 2 includes a fixing belt 21, a fixing pad 22, a pressure roller 23, an axially moving member 24, a heating roller 25, a sliding sheet 26, and the like.

The fixing belt 21 is stretched between a fixing pad 22 and a heating roller 25 that are spaced apart from each other. The fixing belt 21 is made up of a base material made of a metal such as Ni (nickel) or a heat-resistant resin such as PI (polyimide resin), and a silicone rubber layer and a fluororesin release layer sequentially formed on the outer periphery of the base material. The fixing pad 22 is made of heat-resistant resin, metal, or the like, and is fixedly supported so as to be immovable as the fixing belt 21 rotates.

The pressure roller 23 is pressed against the fixing pad 22 via the fixing belt 21, and a fixing nip N is formed between the pressure roller 23 and the fixing belt 21.

The sliding sheet 26 is interposed between the fixing belt 21 and the fixing pad 22. The sliding sheet 26 has a base material made of a heat-resistant resin sheet such as PEEK (polyetheretherketone) or glass fiber, and a fluororesin layer is formed on at least the sliding portion with the fixing belt 21 to reduce sliding resistance. It will be done. The sliding sheet 26 is held between the fixing belt 21 and the fixing pad 22, and the end of the sliding sheet 26 on the upstream side of the fixing nip N is slid so that it slides against the rotation of the fixing belt 21. It is fixedly supported by a movable seat holding member 27.

Although the heating roller 25 has a built-in heat source 25a such as a halogen lamp for heating the fixing belt 21, the method of heating the fixing belt 21 is not limited to this embodiment. Further, large-diameter meandering regulating members (not shown) are formed at both ends of the heating roller 25 in the axial direction, and restrict excessive movement (meandering) of the fixing belt 21 in the rotational axis direction. There is.

The pressure roller 23 is driven by a drive motor (not shown), and as the pressure roller 23 rotates in the direction of arrow R1 by the drive motor, the fixing belt 21 is driven to rotate in the direction of arrow R2 with respect to the pressure roller 23. It is configured. Note that a drive source that rotationally drives the heating roller 25 may be provided so that the fixing belt 1 rotates under the condition that the pressure roller 23 and the fixing belt 21 are separated from each other.

As shown in FIG. 2, the axially movable member 24 is arranged on the upstream side of the fixing nip N so that the axial direction of the axially movable member 24 and the rotational axis direction of the fixing belt 21 are parallel to each other. , the axially moving member 24 is disposed such that its outer surface is in pressure contact with the inner surface of the fixing belt 21. Further, the axially movable member 24 is supported so as to be able to swing in the axial direction via shafts 24a, 24a, so that the fixing belt 21 can be moved within the regulation range of the meandering regulation member provided on the heating roller 25. When the belt meanders in the direction of the rotational axis, a frictional force in the direction of the rotational axis with the fixing belt 21 acts on the axially moving member 24, and the axially moving member 24 also moves in conjunction with the meandering of the fixing belt 21. It is designed to move in the axial direction shown by arrow AB.

As shown in FIG. 2, the axially moving member 24 is a non-rotating member that contacts the inner surface of the fixing belt 21 and slides on the fixing belt 21 without rotating as the fixing belt 21 runs. Also good. Alternatively, as shown in FIG. 3, the roller-like member may be configured to rotate as the fixing belt 21 runs. The axially moving member 24 shown in FIG. 3 is also supported so as to be swingable in the axial direction via shafts 24a, 24a. Furthermore, when the fixing belt 21 meanders in the direction of the rotating shaft within the regulation range of the meandering regulating member provided on the heating roller 25, the frictional force with the fixing belt 21 causes the meandering of the fixing belt 21 to move. , the axially moving member 24 is also adapted to move in the axial direction, as shown by arrows AB in FIG.

A sliding sheet holding member 27 extending in the axial direction of the axially moving member 24 is connected to the axially moving member 24, and the axially moving member 24 moves in conjunction with the movement of the fixing belt 21 in the rotation axis direction. When moving in the axial direction (A-B direction), the sliding sheet holding member 27 also moves together in the same direction, and the sliding sheet 26 whose one end is held by the sliding sheet holding member 27 also moves in the same direction. It looks like this. That is, the axially moving member 24 and the sliding sheet holding member 27 constitute a variable mechanism that moves the sliding sheet 26 in the same direction as the fixing belt 21. In FIG. 1, the symbol G indicated by a broken line indicates that the axially moving member 24 and the sliding sheet holding member 27 are interlocked.

When the axially movable member 24 is composed of a non-rotating member as shown in FIG. Connection can be made even within the range (center in the axial direction). This case is preferable in that deformation of the sliding sheet 26 due to movement of the sliding sheet holding member 27 in the axial direction can be suppressed. In the example of FIG. 2, the sliding sheet holding member 27 is connected to the axially moving member 24 over the entire length thereof.

On the other hand, if the axially moving member 24 is constituted by a rotatable roller-like member as shown in FIG. Since the fixing belt 21 can be configured without a portion that slides on the inner circumferential surface of the fixing belt 21, it is preferable in that driving torque can be reduced and wear of the fixing belt 21 can be prevented. However, since the sliding sheet holding member 27 cannot be connected to the roller-shaped peripheral surface of the axially moving member 24, for example, the sliding sheet holding member 27 is a non-rotatable holding member that holds both ends of the axially moving member 24. It is connected to members 24b, 24b.

The sliding sheet holding member 27 fixes one end of the sliding sheet 26 in its length direction, and is configured to hold the sliding sheet 26 against the frictional force between it and the fixing belt 21 in the fixing nip N. It has become. Examples of methods for fixing the sliding sheet 26 include a method of adhering it to a stay-like high-strength member, and a method of fixing it with screws at multiple locations in the length direction.

In this way, as the fixing belt 21 moves in the direction of the rotation axis (width direction of the fixing belt), the axially moving member 24 also moves in the axial direction, and further, as the axially moving member 24 moves in the axial direction. As a result, the sliding sheet holding member 27 also moves in the direction of the rotation axis similarly to the fixing belt 21.

As a result, the movement of the fixing belt 21 in the rotational axis direction and the movement of the sliding sheet 26 in the width direction coincide, and deformation of the sliding sheet 26 when it is caught in the fixing nip can be suppressed. As a result, it is possible to prevent unevenness in the amount of heat applied to the paper, and to prevent image noise caused by this.
[Second embodiment]
Another embodiment of the invention will be described with reference to FIGS. 4 and 5. In this embodiment, when the fixing belt 1 is moved in the direction of the rotation axis by the steering means, the sliding sheet 26 is moved in the same direction in conjunction with the steering means. Note that illustration of the image forming section 3 is omitted.

Specifically, as shown in FIG. 5, the steering means 240 includes an axially moving member 24 and a steering drive section 241. The axially moving member 24 has one end supported by a support member (not shown), and the other end connected to the steering drive unit 241. By driving the other end of the axially movable member 24 by the steering drive unit 241, the axially movable member 24 moves in the CD direction shown by the arrow in FIG. The arrangement angle of the moving member 24 can be changed. By changing the angle of the axially moving member 24, the friction state between the fixing belt 21 and the axially moving member 24 is changed, and the fixing belt 21 is moved in the direction of the rotation axis (width direction of the fixing belt). The direction position can be adjusted.

In this embodiment, as shown in FIG. 4, a sensor 28 is provided that detects the amount of movement of the fixing belt 21 in the direction of the rotational axis, and the steering drive unit 241 operates the axially moving member based on the detection result of the sensor 28. Change the angle of 24.

The sliding sheet holding member 27 is connected to the axially moving member 24 in the same manner as in the first embodiment. That is, when the axially movable member 24 is composed of a non-rotating member, it is fixed in the entire axial direction, and when the axially movable member 24 is in the form of a roller that can rotate in accordance with the running of the fixing belt 1, as shown in FIG. As shown in the figure, the axially movable member 4 is fixed to the holding members 24b, 24b at both ends using a connecting member such as a sheet metal by screws or other methods.

Other configurations such as the fixing belt 21, fixing pad 22, pressure roller 23, heating roller 25, etc. are the same as in the first embodiment, so their explanation will be omitted.

In this embodiment, the steering means 240 and the sliding sheet holding member 27 constitute a variable mechanism for moving the sliding sheet 26. When the central axis of the axially moving member 24 is controlled to tilt in the CD direction at one end side, the central axis of the sliding sheet holding member 27 is also moved to tilt in the CD direction in conjunction with this. be done. In other words, at the same time as the axially moving member 24 is moved, the sliding sheet holding member 27 is also moved, and the amount of movement of the fixing belt 21 and the amount of movement of the sliding sheet 26 immediately before the entrance of the fixing nip are almost the same. Therefore, deformation of the sliding sheet 26 due to the frictional force between the fixing belt 21 and the sliding sheet 26 can be prevented.
[Third embodiment]
Still another embodiment of the invention will be described with reference to FIG. In this embodiment, the amount of movement of the fixing belt 21 in the rotation axis direction is set to be larger than the amount of movement of the sliding sheet holding member 27 in the axial direction.

Note that the configurations of the fixing belt 21, fixing pad 22, pressure roller 23, axially moving member 24, heating roller 25, sliding sheet 26, sliding sheet holding member 27, etc. are the same as in the first embodiment. , the explanation is omitted.

Also, the point that the axially moving member 24 and the sliding sheet holding member 27 are connected is the same as in the first embodiment, but in this embodiment, the axially moving member 24 and the sliding sheet holding member 27 are connected. The position is different from the first embodiment.

Specifically, the distance from the position of the sliding sheet holding member 27 to the entrance of the fixing nip N is longer than the distance (LB) from the tension end of the axially moving member 24 with respect to the fixing belt 21 to the entrance of the fixing nip N. The distance (LS) is set to be long. Therefore, even if the axially moving member 24 and the sliding sheet holding member 27 move by the same amount, the inclination angle of the sliding sheet 26 in the LS range with respect to the rotational axis direction of the fixing nip N is larger than that of the rotational axis of the fixing nip N. This is smaller than the inclination angle of the fixing belt 21 in the LB range with respect to the axial direction, and the meandering amount (the amount of movement per unit time) of the fixing belt 21 is larger than the amount of movement of the sliding sheet 26.

In this way, by setting the amount of movement of the fixing belt 21 to be larger than the amount of movement of the sliding sheet 26, the amount of movement in the direction of the rotation axis is adjusted based on the difference in the amount of movement of the sliding sheet 26 and the fixing belt 21 in the direction of the rotation axis. An appropriate frictional force is generated, and deformation of the sliding sheet 26 can be effectively eliminated.
[Fourth embodiment]
Still another embodiment of the invention will be described with reference to FIG. This embodiment is basically the same as the second embodiment shown in FIGS. 4 and 5 with steering means 240, but the axially moving member 24 and the sliding seat retaining member 27 are connected. The configuration is such that the angle control of the axially moving member 24 and the movement control of the sliding sheet holding member 27 are performed independently.

With this configuration, compared to a configuration in which the axially moving member 24 and the sliding sheet holding member 27 are connected, the degree of freedom in adjusting the movement of the sliding sheet 26 is increased, and more precise deformation prevention control of the sliding sheet 26 is achieved. becomes possible.

Specifically, one end of each of the central axes of the axially moving member 24 and the sliding sheet holding member 27 is used as a fulcrum, and the other end is moved in the direction of arrow C-D by the respective steering drive units 241a and 241b. Accordingly, the axial movement means 24 is provided with steering means 240a and 240b for tilting in the CD direction, and based on the detection result of the sensor 28 that detects the meandering amount (the amount of movement in the rotation axis direction) of the fixing belt 21. and the angle (position in the CD direction) of the sliding sheet holding member 27 are independently controlled. Therefore, in this embodiment, each steering means 240a, 240b constitutes a variable mechanism for moving the sliding seat 26.

As a result, even if the sliding sheet 26 is deformed over time (such as becoming thinner due to tension caused by frictional force at the fixing nip, elongating and becoming uneven, etc.), the sliding sheet holding member 27 can be moved due to durability conditions. By changing the amount (for example, by increasing the difference from the meandering speed of the fixing belt 1), deformation of the sliding sheet 26 due to the meandering of the fixing belt 21 can be stably suppressed.

For example, after long-term use compared to the initial stage, when the axially moving member 24 is controlled in a direction that increases the meandering amount or speed of the fixing belt 21, the sliding sheet 26 slides in a direction that decreases the amount of movement. While controlling the sheet holding member 27, when the axially moving member 24 is controlled in a direction in which the meandering amount or speed of the fixing belt 21 is decreased, the sliding sheet is held in a direction in which the amount of movement of the sliding sheet 26 is increased. Control member 27. Through such control, deformation of the sliding sheet 26 can be stably suppressed.
[Fifth embodiment]
Still another embodiment of the invention will be described with reference to FIG. In this embodiment, a heating roller 25 that is stretched around the inner periphery of the fixing belt 21 and has a function of heating the fixing belt 21 also serves as an axially moving member.

That is, the heating roller 25 is provided with a steering means 240c that adjusts the meandering of the fixing belt 21 by moving the heating roller 25 with one end of its central axis as a fulcrum and the other end thereof in the direction of arrow CD by a steering drive unit 241c. The angle (position in the CD direction) of the heating roller 25 is controlled based on the detection result of a sensor 28 that detects the meandering amount (position in the rotation axis direction) of the fixing belt 21.

On the other hand, the sliding sheet holding member 27 also has one end of its central axis as a fulcrum and the other end is moved in the direction of arrow CD by the steering drive unit 241d, thereby controlling the amount of movement of the sliding sheet 26. Means 240d is provided. As described in the fourth embodiment, by controlling the angles of the heating roller 25 and the sliding sheet holding member 27, deformation of the sliding sheet 26 near the entrance of the fixing nip N can be effectively suppressed.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, a lubricant (fluorine oil, heat-resistant grease) may be interposed on the contact surface between the sliding sheet 26 and the fixing belt 21 to stably reduce the frictional force between the fixing belt 21 and the sliding sheet 26. Since deformation of the sliding sheet 26 is suppressed, occurrence of lubricant unevenness due to lubricant accumulation can be prevented, and image noise can be prevented. When a lubricant is used, a high friction layer made of silicone rubber or the like is applied to the surface of the axially movable member 24 in order to ensure the frictional force with the inner surface of the fixing belt 21 and facilitate the movement of the axially movable member 24. It may be formed.

1 Image forming device 2 Fixing device 3 Image forming section 4 Conveyance path 21 Fixing belt 22 Fixing pad 23 Pressure roller 24 Axial moving member 25 Heat roller 26 Sliding sheet 27 Sliding sheet holding member 28 Sensor 231 Drive motor 240 Steering means N Fixing nip

Claims (10)

A rotating fixing belt,
a pressure roller that presses against the fixing belt from outside to form a fixing nip;
a sliding sheet that is arranged to contact the inner surface of the fixing belt and slide with the fixing belt;
a fixing pad that is pressed against the fixing belt with the sliding sheet in between and is pressed against the pressure roller;
a variable mechanism that moves the sliding sheet in the direction of the rotation axis of the fixing belt in response to movement in the rotation axis direction of the fixing belt ;
A fixing device characterized by comprising: A rotating fixing belt,
a pressure roller that presses against the fixing belt from outside to form a fixing nip;
a sliding sheet that is arranged to contact the inner surface of the fixing belt and slide with the fixing belt;
a fixing pad that is pressed against the fixing belt with the sliding sheet in between and is pressed against the pressure roller;
a variable mechanism that moves the sliding sheet in response to movement of the fixing belt in the rotation axis direction;
Equipped with
The variable mechanism includes an axially moving member that is disposed upstream of the fixing nip and moves in conjunction with movement of the fixing belt in the rotational axis direction,
The fixing device is characterized in that the sliding sheet moves in conjunction with the movement of the axially moving member. A rotating fixing belt,
a pressure roller that presses against the fixing belt from outside to form a fixing nip;
a sliding sheet that is arranged to contact the inner surface of the fixing belt and slide with the fixing belt;
a fixing pad that is pressed against the fixing belt with the sliding sheet in between and is pressed against the pressure roller;
a variable mechanism that moves the sliding sheet in response to movement of the fixing belt in the rotation axis direction;
Equipped with
The variable mechanism is
a detection means for detecting the amount of movement of the fixing belt in the rotation axis direction;
Steering means for changing the contact state with the fixing belt and moving the fixing belt in the direction of the rotation axis based on the detection result of the detection means;
Equipped with
The fixing device is characterized in that the sliding sheet moves in accordance with the movement of the fixing belt in the rotational axis direction by the steering means. The variable mechanism includes an axially moving member that is disposed upstream of the fixing nip and moves in conjunction with movement of the fixing belt in the rotational axis direction,
The fixing device according to claim 1, wherein the sliding sheet moves in conjunction with movement of the axially moving member. The axially moving member is a roller-shaped member whose circumferential surface is pressed against the inner circumferential surface of the fixing belt, and configured to move in the direction of the rotation axis in conjunction with the fixing belt due to frictional force with the fixing belt. can be,
a sliding sheet holding member that holds an end of the sliding sheet on the upstream side of the fixing nip;
5. The fixing device according to claim 2 , wherein the sliding sheet holding member is connected to holding members that hold both ends of the roller-like member. The variable mechanism is
a detection means for detecting the amount of movement of the fixing belt in the rotation axis direction;
Steering means for changing the contact state with the fixing belt and moving the fixing belt in the direction of the rotation axis based on the detection result of the detection means;
Equipped with
2. The fixing device according to claim 1, wherein the sliding sheet moves in response to movement of the fixing belt in the rotational axis direction by the steering means. The fixing device according to claim 1 , wherein the amount of movement of the fixing belt is greater than the amount of movement of the sliding sheet. The steering means includes:
Claims 3 and 6, Claim 7 citing Claim 3 or 6, further comprising a heating roller that supports the inner circumferential surface of the fixing belt and stretches the fixing belt, and that heats the fixing belt. The fixing device according to any one of. 9. The fixing device according to claim 1 , wherein the variable mechanism moves the sliding sheet independently of movement of the fixing belt. an image forming means;
A fixing device according to any one of claims 1 to 9 , which fixes the image formed by the image forming means and transferred to the paper;
An image forming apparatus comprising:

Images