JP6897375B2 - Fixing device - Google Patents

Description

The present invention relates to a fixing device for heat-fixing a developer image on a recording sheet in an image forming device.

There is known a fixing device in which a pressure pad is provided in an endless belt and the endless belt is sandwiched between the pressure pad and a roller (Patent Document 1). This fixing device heat-fixes the developer image to the paper while transporting the recording sheet on which the developer image is formed between the endless belt and the roller.

Then, this fixing device changes the nip width, which is the width of the nip surface of the endless belt and the roller, in the transport direction of the recording sheet, by moving the pressure pad forward and backward with respect to the roller.

Japanese Unexamined Patent Publication No. 2015-108721

By the way, depending on the type of recording sheet and the usage environment of the image forming apparatus, the shape of the nip surface and the pressure distribution may be changed according to the situation in order to suppress wrinkles on the recording sheet and paper jams. Is desired.

However, as in the prior art, if the entire pressure pad is simply moved back and forth with respect to the roller, the size of the nip width can be changed over the entire width direction of the recording sheet, but the nip. It was not possible to freely change the shape of the surface and the pressure distribution in the nip surface.

Therefore, it is an object of the present invention to provide a fixing device capable of changing the shape and pressure distribution of the nip surface in various ways.

In order to solve the above problems, the fixing device of the present invention pressurizes the endless belt, the first surface in contact with the inner peripheral surface of the endless belt, and the second surface located on the opposite side of the first surface. A roller that sandwiches an endless belt between the pad and the pressure pad and conveys the recording sheet between the endless belt in the conveying direction, and a first cam that contacts the second surface in the axial direction of the roller. A first cam that rotates around the extending first axis, a first cam that rotates to a second rotation position different from the first rotation position, and a second cam that contacts the second surface. A second that is arranged on the downstream side in the transport direction with respect to one cam and rotates around a second axis extending in the axial direction to a third rotation position and a fourth rotation position different from the third rotation position. Equipped with a cam.
The first cam has a first upstream contact surface that contacts the second surface when in the first rotation position and a second upstream contact surface that contacts the second surface when in the second rotation position. ..
The second cam has a first downstream contact surface that contacts the second surface when in the third rotation position and a second downstream contact surface that contacts the second surface when in the fourth rotation position. ..
Then, the distance from the first axis to the center of the first upstream contact surface in the axial direction is set to D1 uc.
The distance from the first axis to the end of the first upstream contact surface in the axial direction is D1ue,
The distance from the first axis to the center of the second upstream contact surface in the axial direction is D2uc,
The distance from the first axis to the end of the second upstream contact surface in the axial direction is D2ue,
The distance from the second axis to the center of the first downstream contact surface in the axial direction is D1dc.
The distance from the second axis to the end of the first downstream contact surface in the axial direction is D1de,
The distance from the second axis to the center of the second downstream contact surface in the axial direction is D2dc,
The distance from the second axis to the end of the second downstream contact surface in the axial direction is D2de.
D2uc-D2ue is different from D1uc-D1ue.
D2dc-D2de is different from D1dc-D1de.
D2dc-D2de is different from D2uc-D2ue.

According to such a configuration, the first cam is positioned at either the first rotation position or the second rotation position, and the second cam is positioned at either the third rotation position or the fourth rotation position. By doing so, the portion of the pressure pad on the upstream side in the transport direction is pressed by the first upstream contact surface or the second upstream contact surface, and the portion on the downstream side in the transport direction is in contact with the first downstream contact surface or the second downstream contact surface. Pressed by the surface. Therefore, the pressing force of the central portion and the end portion in the axial direction of the portion upstream of the transport direction of the pressure pad and the pressing force of the central portion and the end portion in the axial direction of the portion downstream of the transport direction are first. It can be appropriately changed according to the shapes of the cam and the second cam. Therefore, according to this fixing device, it is possible to change the shape and pressure distribution of the nip surfaces of the endless belt and the roller in various ways.

In order to solve the above-mentioned problems, the fixing device of the present invention includes an endless belt, a first surface in contact with the inner peripheral surface of the endless belt, and a second surface located on the opposite side of the first surface. A roller that sandwiches an endless belt between the pressure pad and the pressure pad and conveys the recording sheet between the endless belt in the conveying direction, and a cam that contacts the second surface and extends in the axial direction of the roller. A cam that can rotate around a cam axis is provided with a first rotation position and a second rotation position different from the first rotation position.
When the cam is in the first rotation position, the first upstream contact surface that contacts the second surface and the first downstream contact that contacts the second surface on the downstream side in the transport direction from the first upstream contact surface. A surface, a second upstream contact surface that contacts the second surface when in the second rotation position, and a second downstream contact surface that contacts the second surface on the downstream side in the transport direction from the second upstream contact surface. And have.
Then, the distance from the cam axis to the center of the first upstream contact surface in the axial direction is set to D1 uc.
The distance from the cam axis to the end of the first upstream contact surface in the axial direction is D1ue,
The distance from the cam axis to the center of the second upstream contact surface in the axial direction is D2uc,
The distance from the cam axis to the end of the second upstream contact surface in the axial direction is D2ue,
The distance from the cam axis to the center of the first downstream contact surface in the axial direction is D1dc.
The distance from the cam axis to the end of the first downstream contact surface in the axial direction is D1de,
The distance from the cam axis to the center of the second downstream contact surface in the axial direction is D2dc,
The distance from the cam axis to the end of the second downstream contact surface in the axial direction is D2de.
D2uc-D2ue is different from D1uc-D1ue.
D2dc-D2de is different from D1dc-D1de.
D2dc-D2de is different from D2uc-D2ue.

According to such a configuration, by positioning the cam at either the first rotation position or the second rotation position, the portion of the pressure pad on the upstream side in the transport direction becomes the first upstream contact surface or the first upstream contact surface. 2 It is pressed by the upstream contact surface, and the portion on the downstream side in the transport direction is pressed by the first downstream contact surface or the second downstream contact surface. Therefore, the pressing force of the central portion and the end portion in the axial direction of the portion upstream of the transport direction of the pressure pad and the pressing force of the central portion and the end portion in the axial direction of the portion downstream of the transport direction are applied to the cam. It can be changed as appropriate according to the shape. Therefore, according to this fixing device, it is possible to change the shape and pressure distribution of the nip surfaces of the endless belt and the roller in various ways.

In order to solve the above-mentioned problems, the fixing device of the present invention has an endless belt, a first surface in contact with the inner peripheral surface of the endless belt, and a second surface located on the opposite side of the first surface. A roller that sandwiches an endless belt between the pressure pad and the pressure pad and conveys the recording sheet between the endless belt in the conveying direction, and a plurality of rollers that are aligned in the axial direction of the roller and can press the second surface. It has an upstream pressing mechanism having an upstream pressing pin and a plurality of downstream pressing pins arranged on the downstream side in the transport direction with respect to the upstream pressing mechanism and arranged in the axial direction of the roller and capable of pressing the second surface. A downstream pressing mechanism and a control device capable of moving a plurality of upstream pressing pins and a plurality of downstream pressing pins forward and backward with respect to a second surface, wherein a plurality of upstream pressing pins and a plurality of downstream pressing pins are used. Is provided with a control device that moves the first state and a second state different from the first state.
And
A plane that is parallel to the plane passing through both ends of the first surface in the transport direction and is opposite to the axis of the roller with respect to the tips of the plurality of upstream pressing pins and the plurality of downstream pressing pins is used as a reference plane. age,
In the first state, the distance from the reference plane to the tip of the upstream pressing pin at the center in the axial direction is D1 uc.
In the first state, the distance from the reference plane to the tip of the upstream pressing pin at the end in the axial direction is D1ue.
In the second state, the distance from the reference plane to the tip of the upstream pressing pin at the center in the axial direction is D2uc.
In the second state, the distance from the reference plane to the tip of the upstream pressing pin at the end in the axial direction is D2ue,
In the first state, the distance from the reference plane to the tip of the downstream pressing pin at the center in the axial direction is D1dc.
In the first state, the distance from the reference plane to the tip of the downstream pressing pin at the end in the axial direction is D1de.
In the second state, the distance from the reference plane to the tip of the downstream pressing pin in the central portion in the axial direction is D2dc.
In the second state, the distance from the reference plane to the tip of the downstream pressing pin at the end in the axial direction is D2de.
D2uc-D2ue is different from D1uc-D1ue.
D2dc-D2de is different from D1dc-D1de.
D2dc-D2de is different from D2uc-D2ue.

According to such a configuration, the plurality of upstream pressing pins of the upstream pressing mechanism and the plurality of downstream pressing pins of the downstream pressing mechanism are brought into the first state or the second state, so that the pressure pad is on the upstream side in the transport direction. Is pressed by the upstream pressing pin and the downstream pressing pin, and the pressure pad is pressed according to the amount of protrusion of each pressing pin. Therefore, according to this fixing device, it is possible to change the shape and pressure distribution of the nip surfaces of the endless belt and the roller in various ways.

According to the present invention, it is possible to change the shape and pressure distribution of the nip surfaces of the endless belt and the roller in various ways.

It is sectional drawing of the laser printer provided with the fixing device which concerns on this invention. It is sectional drawing of the fixing device which concerns on 1st Embodiment. It is a perspective view which shows the structure of the fixing device. It is sectional drawing of the cam, and shows the 4A cross section (a), 4B cross section (b), and 4C cross section (c) of FIG. It is sectional drawing of the cam, and shows 5A sectional (a), 5B sectional (b), and 5C sectional (c) of FIG. It is a figure (a) which shows the position of each cam when the 1st cam and the 2nd cam are in the 1st state, and the figure (b) which shows the shape of the nip surface. It is a figure (a) which shows the position of each cam when the 1st cam and the 2nd cam are in the 2nd state, and the figure (b) which shows the shape of the nip surface. It is a figure (a) which shows the position of each cam when the 1st cam and the 2nd cam are in the 3rd state, and the figure (b) which shows the shape of the nip surface. It is sectional drawing of the fixing device which concerns on 2nd Embodiment, and is the figure which the cam is in the 1st rotation position. It is sectional drawing of the fixing device which concerns on 2nd Embodiment, and is the figure which the cam is in the 2nd rotation position. It is sectional drawing of the cam, and shows the 10A cross section (a), 10B cross section (b), 10C cross section (c) and 10D cross section (d) of FIG. It is sectional drawing of the fixing device which concerns on 3rd Embodiment. It is sectional drawing of the fixing device which concerns on 4th Embodiment. It is a figure (a) which looked at a plurality of upstream pressing pins in a 1st state from a transport direction, and is a figure (b) which looked at a plurality of downstream pressing pins in a 1st state from a transport direction. It is a figure (a) which looked at the plurality of upstream pressing pins in a 2nd state from the transport direction, and is the figure (b) which looked at the plurality of downstream pressing pins in a 2nd state from a transport direction.

[First Embodiment]
Next, the fixing device according to the first embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, unless otherwise specified, the vertical direction shown in FIG. 1 is up and down, the right side in FIG. 1 is the front, the left side is the back, the front side of the paper is the left, and the back side of the paper is the right. Is shown.

As shown in FIG. 1, the laser printer 10 including the fixing device 100 according to the first embodiment has a paper feeding unit 30 for supplying paper P as an example of a recording sheet and an exposure device 40 in the main body housing 20. A process cartridge 50 for transferring the toner image onto the paper P and a fixing device 100 for thermally fixing the toner image on the paper P are mainly provided.

The paper feed unit 30 is provided in the lower part of the main body housing 20, and is provided with a paper feed tray 31 for accommodating the paper P, a paper pressing plate 32 for lifting the front side of the paper P, a paper feed roller 33, and a paper feed pad 34. , The paper dust removing rollers 35 and 36, and the resist roller 37 are mainly provided. The paper P in the paper feed tray 31 is brought to the paper feed roller 33 by the paper pressing plate 32, separated one by one by the paper feed roller 33 and the paper feed pad 34, and the paper dust removing rollers 35 and 36 and the resist roller 37 are separated. It is conveyed toward the process cartridge 50 through the process cartridge 50.

The exposure apparatus 40 is arranged in the upper part of the main body housing 20, and mainly includes a laser emitting unit (not shown), a polygon mirror 41 that is rotationally driven, lenses 42, 43, and reflectors 44, 45, 46. There is. In the exposure apparatus 40, the laser beam emitted from the laser emitting unit is reflected or passed in the order of the polygon mirror 41, the lens 42, the reflecting mirrors 44, 45, the lens 43, and the reflecting mirror 46, and is reflected or passed through the surface of the photoconductor drum 61. It is scanned at high speed.

The process cartridge 50 is arranged below the exposure apparatus 40 and is removable from the main body housing 20 through an opening formed when the front cover 21 provided in the main body housing 20 is opened. The process cartridge 50 includes a drum unit 60 and a developing unit 70.

The drum unit 60 mainly includes a photoconductor drum 61, a charger 62, and a transfer roller 63. Further, the developing unit 70 is detachable from the drum unit 60, and mainly includes a developing roller 71, a supply roller 72, a layer thickness regulating blade 73, and a toner accommodating portion 74 for accommodating toner. There is.

In the process cartridge 50, the surface of the photoconductor drum 61 is uniformly charged by the charger 62 and then exposed by high-speed scanning of the laser beam from the exposure apparatus 40, so that the photoconductor drum 61 is electrostatically charged. A latent image is formed. Further, the toner in the toner accommodating portion 74 is supplied to the developing roller 71 via the supply roller 72, enters between the developing roller 71 and the layer thickness regulating blade 73, and forms a thin layer having a constant thickness on the developing roller 71. It is carried on.

The toner supported on the developing roller 71 is supplied from the developing roller 71 to the electrostatic latent image formed on the photoconductor drum 61. As a result, the electrostatic latent image is visualized and a toner image is formed on the photoconductor drum 61. After that, the paper P is conveyed between the photoconductor drum 61 and the transfer roller 63, so that the toner image on the photoconductor drum 61 is transferred onto the paper P.

The fixing device 100 is provided behind the process cartridge 50. The toner image transferred onto the paper P is heat-fixed on the paper P by passing through the fixing device 100. The paper P on which the toner image is heat-fixed is discharged onto the paper output tray 22 by the transport rollers 23 and 24.

As shown in FIGS. 2 and 3, the fixing device 100 includes an endless belt 110, a halogen lamp 120 as a heater, a reflective member 130, a pressure pad 140, a first cam 150, and a second cam 160. The support member 170, the motors 81 and 82, the control device 90, and the pressurizing roller 180 as an example of the roller are provided.

The endless belt 110 is an endless belt having heat resistance and flexibility, and has a raw tube made of a metal such as stainless steel and a coat layer made of a fluororesin formed on the surface of the raw tube. It is mainly composed of having. Both ends of the endless belt 110 are rotatably supported by side guides (not shown). A halogen lamp 120, a reflective member 130, a pressure pad 140, a first cam 150, and a second cam 160 are arranged inside the endless belt 110.

The halogen lamp 120 is a heater that heats the endless belt 110. The halogen lamp 120 is arranged at a predetermined distance from the inner peripheral surface 111 of the endless belt 110.

The reflection member 130 is a member that reflects the radiant heat from the halogen lamp 120 toward the inner peripheral surface 111 of the endless belt 110, and is arranged at a predetermined interval from the halogen lamp 120. Specifically, the reflective member 130 is arranged below the halogen lamp 120 and reflects the radiant heat from the halogen lamp 120 upward to heat the upper part of the endless belt 110.

The pressure pad 140 is a flat plate-shaped member that is long in the left-right direction. The pressure pad 140 is an elastic member such as rubber, foam rubber, or foam resin. The pressure pad 140 has a first surface 141 that contacts the inner peripheral surface of the endless belt 110 and a second surface 142 that is located on the opposite side of the first surface 141.

The pressure roller 180 is configured to rotate around the axis 181A by transmitting a driving force from a motor (not shown) provided in the main body housing 20, and the endless belt 110 is driven to rotate. The endless belt 110 is driven to rotate by the frictional force with. The paper P on which the toner image is transferred is conveyed between the pressure roller 180 and the heated endless belt 110, so that the toner image is heat-fixed.

The pressurizing roller 180 is a roller that sandwiches the endless belt 110 with the pressurizing pad 140 and conveys the paper P with the endless belt 110 in the conveying direction. The pressure roller 180 mainly has a metal shaft 181 and an elastic roller body 182 provided on the outer periphery of the shaft 181.

The first cam 150 is a cam having a shaft 159 and rotating around the first axis 150A extending in the axial direction of the pressurizing roller 180 (hereinafter, simply referred to as “axial direction”). As shown in FIG. 2, the first cam 150 has a first upstream contact surface 151, a second upstream contact surface 152, and a third upstream contact surface 153 at different positions around the first axis 150A. The first cam 150 comes into contact with the second surface 142 of the pressure pad 140, and the first rotation position shown in FIGS. 2 and 6A and the second rotation position shown in FIG. 7, which is different from the first rotation position. It rotates to the rotation position and the fifth rotation position shown in FIG. 8, which is different from the first rotation position and the second rotation position.

The second cam 160 is a cam having a shaft 169 and rotating around a second axis 160A extending in the axial direction of the pressurizing roller 180. As shown in FIG. 2, the second cam 160 has a first downstream contact surface 161, a second downstream contact surface 162, and a third downstream contact surface 163 at different positions around the second axis 160A. The second cam 160 comes into contact with the second surface 142 of the pressure pad 140, and the third rotation position shown in FIGS. 2 and 6A and the fourth rotation position shown in FIG. 7, which is different from the third rotation position. It rotates to the rotation position and the sixth rotation position shown in FIG. 8, which is different from the third rotation position and the fourth rotation position.

As shown in FIG. 3, a gear 158 is fixed to the end of the shaft 159. An idle gear 157 is engaged with the gear 158, and a driving force of the motor 81 is input to the idle gear 157 via a gear group (not shown).
A gear 168 is fixed to the shaft 169. An idle gear 167 is engaged with the gear 168, and a driving force of the motor 82 is input to the idle gear 167 via a gear group (not shown).

The motors 81 and 82 are, for example, stepping motors. The motors 81 and 82 are connected to the control device 90, and can be rotated by an arbitrary angle by the control device 90, respectively. That is, the first cam 150 and the second cam 160 can rotate independently.

The shafts 159, 169, idle gears 157, 167 and the pressure pad 140 are supported by the support member 170. Although only one end side of the endless belt 110 is shown in FIG. 3, the shafts 159, 169 and the pressure pad 140 are also supported by a support member 170 (not shown) on the other end side of the endless belt 110. That is, the relative positions of the pressure pad 140 and the shafts 159 and 169 are fixed by the support member 170.

The control device 90 is a device that has a CPU, a ROM, a RAM, and the like, and outputs a control signal to each device of the laser printer 10 to control the entire image forming operation. The control device 90 outputs control signals to the motors 81 and 82 according to the type of paper P included in the print data and instructions from the operation panel to rotate the first cam 150 and the second cam 160, and these Is configured to transition to a first state, a second state, or a third state.

The first state is a state in which the first cam 150 is in the first rotation position and the second cam 160 is in the third rotation position, as shown in FIGS. 2 and 6A. When the first cam 150 is in the first rotation position, the first upstream contact surface 151 comes into contact with the second surface 142 of the pressure pad 140. When the second cam 160 is in the third rotation position, the first downstream contact surface 161 comes into contact with the second surface 142 of the pressure pad 140.

In the second state, as shown in FIG. 7, the first cam 150 is in the second rotation position and the second cam 160 is in the fourth rotation position. When the first cam 150 is in the second rotation position, the second upstream contact surface 152 comes into contact with the second surface 142 of the pressure pad 140. When the second cam 160 is in the third rotation position, the second downstream contact surface 162 comes into contact with the second surface 142 of the pressure pad 140.

In the third state, as shown in FIG. 8, the first cam 150 is in the fifth rotation position and the second cam 160 is in the sixth rotation position. When the first cam 150 is in the fifth rotation position, the third upstream contact surface 153 comes into contact with the second surface 142 of the pressure pad 140. When the second cam 160 is in the sixth rotation position, the third downstream contact surface 163 comes into contact with the second surface 142 of the pressure pad 140.

As shown in FIG. 4A, the central portion of the first upstream contact surface 151 of the first cam 150 in the axial direction protrudes radially from the end portion. That is, the distance D1uc from the first axis 150A to the central portion of the first upstream contact surface 151 in the axial direction is larger than the distance D1ue from the first axis 150A to the end of the first upstream contact surface 151 in the axial direction.
In the present invention, the end portion in the axial direction of each contact surface means the end portion in the range of contact with the pressure pad 140.

As shown in FIG. 4B, the third upstream contact surface 153 of the first cam 150 has a central portion and an end portion in the axial direction at the same positions in the radial direction. That is, the distance D3uc from the first axis 150A to the center of the third upstream contact surface 153 in the axial direction is equal to the distance D3ue from the first axis 150A to the end of the third upstream contact surface 153 in the axial direction.

As shown in FIG. 4C, the second upstream contact surface 152 of the first cam 150 has a central portion in the axial direction recessed in the radial direction from the end portion. That is, the distance D2uc from the first axis 150A to the central portion of the second upstream contact surface 152 in the axial direction is smaller than the distance D2ue from the first axis 150A to the end of the second upstream contact surface 152 in the axial direction.
That is, D2uc-D2ue is different from D1uc-D1ue.
Further, D2uc-D2ue <D1uc-D1ue.

As shown in FIG. 5A, the central portion of the first downstream contact surface 161 of the second cam 160 in the axial direction protrudes radially from the end portion. That is, the distance D1dc from the second axis 160A to the center of the first downstream contact surface 161 in the axial direction is larger than the distance D1de from the second axis 160A to the end of the first downstream contact surface 161 in the axial direction. The amount of protrusion of the first downstream contact surface 161 with respect to the end of the central portion in the axial direction is larger than the amount of protrusion of the first upstream contact surface 151 with respect to the end of the central portion in the axial direction.
That is, D1dc-D1de is different from D1uc-D1ue.
Further, D1dc-D1de> D1uc-D1ue.

As shown in FIG. 5B, the third downstream contact surface 163 of the second cam 160 has a central portion and an end portion in the axial direction at the same positions in the radial direction. That is, the distance D3dc from the second axis 160A to the center of the third downstream contact surface 163 in the axial direction is equal to the distance D3de from the second axis 160A to the end of the third downstream contact surface 163 in the axial direction.

As shown in FIG. 5C, the second downstream contact surface 162 of the second cam 160 has a central portion in the axial direction recessed in the radial direction from the end portion. That is, the distance D2dc from the second axis 160A to the center of the second downstream contact surface 162 in the axial direction is smaller than the distance D2de from the second axis 160A to the end of the second downstream contact surface 162 in the axial direction.
That is, D2dc-D2de is different from D1dc-D1de.
Further, D2dc-D2de <D1dc-D1de.
The amount of dent with respect to the end of the central portion of the second downstream contact surface 162 in the axial direction is larger than the amount of dent with respect to the end of the central portion of the second upstream contact surface 152 in the axial direction.
That is, D2dc-D2de is different from D2uc-D2ue.
Further, D2dc-D2de <D2uc-D2ue (| D2dc-D2de |> | D2uc-D2ue |).

The operation and effect of the fixing device 100 of the laser printer 10 configured as described above will be described.
The fixing device 100 outputs control signals to the motors 81 and 82 according to the type of paper P included in the print data and instructions from the operation panel, and rotates the first cam 150 and the second cam 160 in a predetermined direction. Let me.

For example, when a horizontal grain paper (paper in which the fiber direction is orthogonal to the transport direction) is specified, the control device 90 sets the first cam 150 in the first rotation position and sets the first cam 150 to the first rotation position as shown in FIG. 6A. 2 The cam 160 is set to the third rotation position to be in the first state. In the first state, in the first cam 150 and the second cam 160, the first upstream contact surface 151 and the first downstream contact surface 161 come into contact with the second surface 142. In both the first upstream contact surface 151 and the first downstream contact surface 161, the central portion in the axial direction protrudes from the end portion. In particular, the amount of protrusion of the central portion with respect to the end of the first downstream contact surface 161 on the downstream side in the transport direction is larger than the amount of protrusion of the central portion with respect to the end of the first upstream contact surface 151.
In this state, as shown in FIG. 6B, the nip surface N has a shape in which the central portion in the axial direction protrudes in the transport direction from the end portion on the upstream side and the downstream side in the transport direction. Regarding the width of the nip surface N of the endless belt 110 and the pressure roller 180 in the transport direction (hereinafter, simply referred to as “nip width”), the width of the central portion in the axial direction is N1c, and the width of the end portion in the axial direction is N1c. The width is N1e, and N1c> N1e is satisfied. Since the central portion in the axial direction of the nip surface N protrudes from the end portion on the downstream side in the transport direction, wrapping around the endless belt 110 is suppressed even for horizontal grain paper, and the paper is separated from the endless belt 110. Becomes good.

Further, for example, when thin paper is specified, as shown in FIG. 7A, the control device 90 sets the first cam 150 in the second rotation position and the second cam 160 in the fourth rotation position. Put it in the second state. In the second state, in the first cam 150 and the second cam 160, the second upstream contact surface 152 and the second downstream contact surface 162 come into contact with the second surface 142. Both the second upstream contact surface 152 and the second downstream contact surface 162 have a central portion in the axial direction recessed with respect to an end portion. In particular, the amount of dent in the central portion with respect to the end of the second downstream contact surface 162 on the downstream side in the transport direction is larger than the amount of dent in the central portion with respect to the end of the second upstream contact surface "152 on the upstream side in the transport direction. There is.
In this state, as shown in FIG. 7B, the nip surface N has a shape in which the central portion in the axial direction is recessed in the transport direction from the end portion on the upstream side and the downstream side in the transport direction. Regarding the nip width at this time, N2c <N2e is satisfied, where N2c is the width of the central portion in the axial direction and N2e is the width of the end portion in the axial direction. On the downstream side of the nip surface N in the transport direction, the central portion in the axial direction is recessed from the end portion, so that the transport speed at the end portion in the axial direction increases, and the thin paper can be transported while being pulled outward in the axial direction. Since it can be formed, it is possible to prevent the thin paper from wrinkling.

Further, for example, when thick paper is specified, as shown in FIG. 8A, the control device 90 sets the first cam 150 at the fifth rotation position and the second cam 160 at the sixth rotation position. Put it in the third state. In the third state, in the first cam 150 and the second cam 160, the third upstream contact surface 153 and the third downstream contact surface 163 come into contact with the second surface 142. Both the third upstream contact surface 153 and the third downstream contact surface 163 are equidistant from the axes 150A and 160A of the cams 150 and 160 at the center and the ends in the axial direction. Therefore, as shown in FIG. 8B, the nip surface N has a substantially linear shape on the upstream side and the downstream side in the transport direction. By making the nip width of the nip surface N uniform in the axial direction, thick paper can be satisfactorily conveyed.

As described above, according to the fixing device 100 of the present embodiment, the first cam 150 is positioned at any of the first rotation position, the second rotation position, and the fifth rotation position, and the second cam 160 is set. By positioning the pressure pad 140 at any of the third rotation position, the fourth rotation position, and the sixth rotation position, the portion of the pressure pad 140 on the upstream side in the transport direction becomes the first upstream contact surface 151 and the second upstream. It is pressed by the contact surface 152 or the third upstream contact surface 153, and the portion downstream in the transport direction is pressed by the first downstream contact surface 161 and the second downstream contact surface 162 or the third downstream contact surface 163. Therefore, the pressing force of the central portion and the end portion in the axial direction of the portion upstream of the transport direction of the pressure pad 140 and the pressing force of the central portion and the end portion in the axial direction of the portion downstream of the transport direction are different. It can be appropriately changed depending on the positions of the 1st cam 150 and the 2nd cam 160. Therefore, according to this fixing device 100, it is possible to change the shape and pressure distribution of the nip surface N of the endless belt 110 and the pressure roller 180 in various ways.

It should be noted that this embodiment can be appropriately modified and implemented. For example, the fixing device 100 includes a total of two motors, one for each cam, in order to rotate the first cam 150 and the second cam 160 independently. However, one motor is used for the first cam. It may be configured to drive the 150 and the second cam 160. In this case, for example, at least one idle gear that meshes with both the gear 158 and the gear 168 can be provided so that the first cam 150 and the second cam 160 are interlocked with each other.

Further, the combination of the rotation positions of the first cam 150 and the second cam 160 is not limited to the above. For example, when the first cam 150 is set to the first rotation position, the second cam 160 may be set to the fourth rotation position or the sixth rotation position. Further, when the first cam 150 is set to the third rotation position, the second cam 160 may be set to the second rotation position or the sixth rotation position. Further, when the first cam 150 is set to the fifth rotation position, the second cam 160 may be set to the second rotation position or the fourth rotation position.

That is, in the first embodiment, it is configured so that D2dc-D2de <D2uc-D2ue, but it may be configured so that D2dc-D2de> D2uc-D2ue.
Further, in the first embodiment, it is configured so that D1dc-D1de> D1uc-D1ue, but it may be configured so that D1dc-D1de <D1uc-D1ue.

[Second Embodiment]
Next, the second embodiment of the present invention will be described. The fixing device 200 according to the second embodiment shown in FIG. 9 has a different mechanism for pressing the pressure pad 140 with respect to the fixing device 100 of the first embodiment. In the second embodiment, only the points different from those in the first embodiment will be described, and the same reference numerals will be given to the drawings for the same parts, and the description thereof will be omitted.

The fixing device 200 includes a cam 250 that contacts the second surface 142 as a mechanism for pressing the pressure pad 140. The cam 250 is placed around the cam axis 250A extending in the axial direction of the pressure roller 180 at the first rotation position shown in FIG. 9 and the second rotation position shown in FIG. 10, which is different from the first rotation position. It is rotatable.

The cam 250 has a first cam surface 210 and a second cam surface 220 arranged around the cam axis 250A, and has a substantially hexagonal column shape. The first cam surface 210 contacts the second surface 142 of the pressure pad 140 when it is in the first rotation position. The second cam surface 220 comes into contact with the second surface 142 of the pressure pad 140 when it is in the second rotation position.

As shown in FIG. 9, the first cam surface 210 is the first upstream contact surface 211 that contacts the upstream position of the second surface 142 when the cam 250 is in the first rotation position, and the downstream side. It has a first downstream contact surface 212 that contacts the position. That is, the first upstream contact surface 211 and the first downstream contact surface 212 are located on the first cam surface 210. Then, the first downstream contact surface 212 contacts the second surface on the downstream side in the transport direction with respect to the first upstream contact surface 211.

As shown in FIG. 10, the second cam surface 220 is on the downstream side with the second upstream contact surface 221 that contacts the position on the upstream side of the second surface 142 when the cam 250 is in the second rotation position. It has a second downstream contact surface 222 that contacts the position. That is, the second upstream contact surface 221 and the second downstream contact surface 222 are located on the second cam surface 220. Then, the second downstream contact surface 222 contacts the second surface 142 on the downstream side in the transport direction from the second upstream contact surface 221.

As shown in FIG. 11A, the first upstream contact surface 211 has the same shape as the first upstream contact surface 151 of the first embodiment.
As shown in FIG. 11B, the first downstream contact surface 212 has the same shape as the first downstream contact surface 161 of the first embodiment.
As shown in FIG. 11 (c), the second upstream contact surface 221 has the same shape as the second upstream contact surface 152 of the first embodiment.
As shown in FIG. 11D, the second downstream contact surface 222 has the same shape as the second downstream contact surface 162 of the first embodiment.

Therefore, as in the first embodiment,
The distance from the cam axis 250A to the end of the first upstream contact surface 211 in the axial direction is D1ue.
The distance from the cam axis 250A to the center of the first upstream contact surface 211 in the axial direction is D1uc.
The distance from the cam axis 250A to the end of the second upstream contact surface 221 in the axial direction is D2ue,
The distance from the cam axis 250A to the center of the second upstream contact surface 221 in the axial direction is D2uc.
The distance from the cam axis 250A to the end of the first downstream contact surface 212 in the axial direction is D1de.
The distance from the cam axis 250A to the center of the first downstream contact surface 212 in the axial direction is D1dc.
The distance from the cam axis 250A to the end of the second downstream contact surface 222 in the axial direction is D2de,
The distance from the cam axis 250A to the center of the second downstream contact surface 222 in the axial direction is D2dc.
D2uc-D2ue is different from D1uc-D1ue.
D2dc-D2de is different from D1dc-D1de.
D2dc-D2de is different from D2uc-D2ue.

Also,
D2uc-D2ue <D1uc-D1ue,
D2dc-D2de <D1dc-D1de,
D2dc-D2de> D2uc-D2ue.

Further, the width of the nip surface N of the endless belt 110 and the pressure roller 180 in the transport direction is
When the cam 250 is in the first rotation position, the width of the central portion in the axial direction is N1c, and the width of the end portion in the axial direction is N1e.
When the cam 250 is in the second rotation position, the width of the central portion in the axial direction is N2c, and the width of the end portion in the axial direction is N2e.
N1c> N1e
And N2c <N2e
Meet.

The fixing device 200 of the second embodiment has only one motor 81 made of a stepping motor as a motor for driving the cam 250. The motor 81 is driven by the control device 90 to position the cam 250 in the first drive position and the second drive position.

According to the fixing device 200 having such a configuration, similarly to the fixing device 100 of the first embodiment, the cam 250 is positioned at the first rotation position or the second rotation position, so that the pressure pad 140 can be moved. The portion on the upstream side in the transport direction is pressed by the first upstream contact surface 211 or the second upstream contact surface 221 and the portion on the downstream side in the transport direction is pressed by the first downstream contact surface 212 or the second downstream contact surface 222. .. Therefore, the pressing force of the central portion and the end portion in the axial direction of the portion upstream of the transport direction of the pressure pad 140 and the pressing force of the central portion and the end portion in the axial direction of the portion downstream of the transport direction are camped. It can be changed as appropriate depending on the position of 250. Therefore, according to the fixing device 200, it is possible to change the shape and pressure distribution of the nip surface N of the endless belt 110 and the pressure roller 180 in various ways.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. Since the fixing device 300 according to the third embodiment shown in FIG. 12 differs from the fixing device 200 of the second embodiment only in the shape of the cam 350, only the points different from those of the second embodiment will be described. Similar parts are designated by the same reference numerals in the drawings and description thereof will be omitted.

The cam 350 has a shaft 360 extending along the cam axis 250A.
Further, the cam 350 has a first protruding portion 351 and a second protruding portion 352, a third protruding portion 353, and a fourth protruding portion 354 that project from the shaft 360 in a direction orthogonal to the cam axis 250A.

The first protruding portion 351 has a first upstream contact surface 211 at its tip.
The second protruding portion 352 has a first downstream contact surface 212 at its tip.
The third protrusion 353 has a second upstream contact surface 221 at its tip.
The fourth protrusion 354 has a second downstream contact surface 222 at its tip.

The cam 350 can be rotated to the first rotation position and the second rotation position by the motor 81, and at the first rotation position shown in FIG. 12, the first upstream contact surface 211 and the first downstream contact surface 212 Contact the second surface 142 of the pressure pad 140.
The second rotation position is a position rotated 180 degrees around the cam axis 250A with respect to the first rotation position (not shown), and the first rotation position is with the second upstream contact surface 221. The second downstream contact surface 222 contacts the second surface 142 of the pressure pad 140.

Even with the fixing device 300 having such a configuration, the same effect as that of the fixing device 200 of the second embodiment can be obtained.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. The fixing device 400 according to the fourth embodiment shown in FIG. 13 has a different mechanism for pressing the pressure pad 140 with respect to the fixing device 100 of the first embodiment. In the fourth embodiment, only the points different from those in the first embodiment will be described, and the same reference numerals will be given to the drawings for the same parts, and the description thereof will be omitted.

The fixing device 400 includes a pressing mechanism 420 as a mechanism for pressing the second surface 142, and a control device 490 for controlling the pressing mechanism 420.
The pressing mechanism 420 includes a base 430, an upstream pressing mechanism 450 provided on the base 430, and a downstream pressing mechanism 460.

The upstream pressing mechanism 450 has a plurality of upstream pressing pins 452 capable of pressing the second surface 142 of the pressure pad 140 arranged in the axial direction of the pressure roller 180 (see FIG. 14A). The upstream pressing pin 452 is supported by the cylinder 451 so as to be movable back and forth toward the second surface 142. The upstream pressing pin 452 has a magnet (not shown), and the cylinder 451 has a coil (not shown).

The downstream pressing mechanism 460 is arranged on the downstream side in the transport direction with respect to the upstream pressing mechanism 450. The downstream pressing mechanism 460 has a plurality of downstream pressing pins 462 capable of pressing the second surface 142 of the pressure pad 140 arranged in the axial direction of the pressure roller 180 (see FIG. 14B). The downstream pressing pin 462 has a magnet (not shown), and the cylinder 461 has a coil (not shown).

The control device 490 is configured to be able to move the plurality of upstream pressing pins 452 and the plurality of downstream pressing pins 462 forward and backward with respect to the second surface 142 of the pressure pad 140. Specifically, by outputting an instruction from the control device 490 to a power source (not shown) and supplying a current to the coils of the cylinders 451 and 461, the upstream pressing pins 452 and the downstream pressing pins 462 are subjected to the current. Advance toward the second surface 142 with a pressing force according to the above.
The control device 490 sets the plurality of upstream pressing pins 452 and the plurality of downstream pressing pins 462 in the first state shown in FIG. 14 and the first state according to the type of paper P included in the print data and the instruction from the operation panel. The state is changed to the second state shown in FIG. 15, which is different from the state.

As shown in FIGS. 14A and 14B, in the first state, the upstream pressing pin 452 and the downstream pressing pin 462 at the center in the axial direction are more than the upstream pressing pin 452 and the downstream pressing pin 462 at the end. It is in a protruding state.
Specifically, first, the plane passing through both ends 142E and 142E (see FIG. 13) of the first surface 141 of the pressure pad 140 in the transport direction is defined as the plane PL1. Then, a plane parallel to the plane PL1 and one plane opposite to the axis 181A of the pressure roller 180 with respect to each tip of the plurality of upstream pressing pins 452 and the plurality of downstream pressing pins 462 is used as a reference plane. Let it be PL2. The reference plane PL2 is not particularly limited as long as the above conditions are satisfied, but in the present embodiment, for example, it is a plane that passes through the position of the upper end of the cylinders 451 and 461.
Then, in the first state, the distance from the reference plane PL2 to the tip of the upstream pressing pin 452 in the central portion in the axial direction is set to D1 uc.
In the first state, the distance from the reference plane PL2 to the tip of the upstream pressing pin 452 at the end in the axial direction is D1ue.
In the first state, the distance from the reference plane PL2 to the tip of the downstream pressing pin 462 in the central portion in the axial direction is D1dc.
In the first state, the distance from the reference plane PL2 to the tip of the downstream pressing pin 462 at the end in the axial direction is D1de.
D1uc-D1ue> 0
And D1dc-D1de> 0
Is.
Further, as in the first embodiment, D1dc-D1de> D1uc-D1ue.

As shown in FIGS. 15A and 15B, in the second state, the upstream pressing pin 452 and the downstream pressing pin 462 at the center in the axial direction are more than the upstream pressing pin 452 and the downstream pressing pin 462 at the end. It is in a retreated state.
In the second state, the distance from the reference plane PL2 to the tip of the upstream pressing pin 452 in the central portion in the axial direction is D2uc.
In the second state, the distance from the reference plane PL2 to the tip of the upstream pressing pin 452 at the end in the axial direction is D2ue.
In the second state, the distance from the reference plane PL2 to the tip of the downstream pressing pin 462 in the central portion in the axial direction is D2dc.
In the second state, the distance from the reference plane PL2 to the tip of the downstream pressing pin 462 at the end in the axial direction is D2de.
D2uc-D2ue <0
And D2dc-D2de <0
Is.
Further, as in the first embodiment, D2dc-D2de <D2uc-D2ue (| D2dc-D2de |> | D2uc-D2ue |).

That is,
D2uc-D2ue is different from D1uc-D1ue.
D2uc-D2ue <D1uc-D1ue.
Also,
D2dc-D2de is different from D1dc-D1de.
D1dc-D1de> D1uc-D1ue.
Also,
D2dc-D2de is different from D2uc-D2ue
D2dc-D2de <D2uc-D2ue.

With such a configuration, the control device 490 puts the plurality of upstream pressing pins 452 and the plurality of downstream pressing pins 462 into the first state shown in FIG. 14, for example, when the horizontal grain paper or the like is fed. Then, as in the first embodiment, the nip surface N has a shape as shown in FIG. 6 (b). Further, the control device 490 sets the plurality of upstream pressing pins 452 and the plurality of downstream pressing pins 462 into the second state shown in FIG. 15, for example, when thin paper or the like is fed. Then, as in the first embodiment, the nip surface N has a shape as shown in FIG. 7 (b).

Therefore, in the first state, the nip width of the central portion in the axial direction is N1c, and the nip width of the end portion in the axial direction is N1e.
In the second state, the nip width of the central portion in the axial direction is N2c, and the nip width of the end portion in the axial direction is N2e.
N1c> N1e
And N2c <N2e
Meet.

In this way, according to the fixing device 400 of the present embodiment, the plurality of upstream pressing pins 452 of the upstream pressing mechanism 450 and the plurality of downstream pressing pins 462 of the downstream pressing mechanism 460 are brought into the first state or the second state. By doing so, the portion of the pressurizing pad 140 on the upstream side in the transport direction is pressed by the upstream pressing pin 452 and the downstream pressing pin 462, and is pressurized according to the protrusion amount of each upstream pressing pin 452 and each downstream pressing pin 462. The pad 140 is pressed. Therefore, according to this fixing device 400, it is possible to change the shape and pressure distribution of the nip surface N of the endless belt 110 and the pressure roller 180 in various ways.

In this embodiment, the arrangement of the protrusion amounts of the upstream pressing pin 452 and the downstream pressing pin 462 is shown only in the first state of FIG. 14 and the second state of FIG. 15, but any arrangement is shown depending on the characteristics of the paper P. Can be realized. For example, an array that realizes all the shapes of the first cam 150 and the second cam 160 shown in the first embodiment can be stored in advance in the storage unit included in the control device 490. Further, the arrangement of the protrusion amount may be corrected according to the environment such as temperature and humidity with respect to the arrangement of the protrusion amount stored in advance.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and can be appropriately modified and implemented.

For example, in the above embodiment, D2uc-D2ue <D1uc-D1ue is configured, but D2uc-D2ue> D1uc-D1ue may be configured.

Further, in the above embodiment, D2dc-D2de> D1dc-D1de is configured, but D2dc-D2de> D1dc-D1de may be configured.

In the above embodiment, the heater is provided in the endless belt, but the heater may not be provided in the endless belt.

In the above-described embodiment, paper P such as horizontal grain paper, thick paper, and thin paper is exemplified as the recording sheet, but the present invention is not limited to this, and the recording sheet may be, for example, a postcard, an OHP sheet, an envelope, or the like. There may be.

In addition, each element described in the said embodiment and the modification may be carried out in arbitrary combination.

10 Laser printer 81 Motor 82 Motor 90 Control device 100 Fixing device 110 Endless belt 111 Inner peripheral surface 140 Pressurized pad 141 First surface 142 Second surface 150 First cam 150A First axis 151 First upstream contact surface 152 Second upstream Contact surface 160 2nd cam 160A 2nd axis 161 1st downstream contact surface 162 2nd downstream contact surface 180 Pressurized roller N Nip surface P Paper PL2 Reference plane

Claims (20)

With an endless belt
A pressure pad having a first surface in contact with the inner peripheral surface of the endless belt and a second surface located on the opposite side of the first surface.
A roller that sandwiches the endless belt with the pressure pad and conveys the recording sheet between the endless belt and the recording sheet in the conveying direction.
The first cam in contact with the second surface rotates around the first axis extending in the axial direction of the roller to a first rotation position and a second rotation position different from the first rotation position. The first cam to do and
A second cam in contact with the second surface, which is arranged on the downstream side in the transport direction with respect to the first cam, and has a third rotation position and the third rotation position around the second axis extending in the axial direction. It is equipped with a second cam that rotates to a fourth rotation position different from the third rotation position.
The first cam
The first upstream contact surface that contacts the second surface when in the first rotation position,
It has a second upstream contact surface that contacts the second surface when it is in the second rotation position.
The second cam
The first downstream contact surface that contacts the second surface when in the third rotation position,
It has a second downstream contact surface that contacts the second surface when it is in the fourth rotation position.
The distance from the first axis to the center of the first upstream contact surface in the axial direction is D1 uc.
The distance from the first axis to the end of the first upstream contact surface in the axial direction is D1ue.
The distance from the first axis to the center of the second upstream contact surface in the axial direction is D2uc.
The distance from the first axis to the end of the second upstream contact surface in the axial direction is D2ue,
The distance from the second axis to the center of the first downstream contact surface in the axial direction is D1dc.
The distance from the second axis to the end of the first downstream contact surface in the axial direction is D1de.
The distance from the second axis to the center of the second downstream contact surface in the axial direction is D2dc.
The distance from the second axis to the end of the second downstream contact surface in the direction of the axis is defined as D2de.
D2uc-D2ue is different from D1uc-D1ue.
D2dc-D2de is different from D1dc-D1de.
The fixing device D2dc-D2de is different from D2uc-D2ue. The fixing device according to claim 1, wherein the first cam and the second cam can rotate independently. The fixing device according to claim 1 or 2, further comprising at least one motor for rotating the first cam and the second cam. The width of the endless belt and the nip surface of the roller in the transport direction is
When the first cam is in the first rotation position and the second cam is in the third rotation position, the width of the central portion in the axial direction is N1c, and the width of the end portion in the axial direction is N1e. ,
When the first cam is in the second rotation position and the second cam is in the fourth rotation position, the width of the central portion in the axial direction is N2c, and the width of the end portion in the axial direction is N2e. , As,
N1c> N1e
And N2c <N2e
The fixing device according to any one of claims 1 to 3, wherein the fixing device satisfies. With an endless belt
A pressure pad having a first surface in contact with the inner peripheral surface of the endless belt and a second surface located on the opposite side of the first surface.
A roller that sandwiches the endless belt with the pressure pad and conveys the recording sheet between the endless belt and the recording sheet in the conveying direction.
A cam that comes into contact with the second surface and is rotatable around the cam axis extending in the axial direction of the roller to a first rotation position and a second rotation position different from the first rotation position. With and
The cam
When in the first rotation position, the first upstream contact surface that contacts the second surface and the first downstream that contacts the second surface on the downstream side in the transport direction from the first upstream contact surface. The contact surface and the second upstream contact surface that contacts the second surface when in the second rotation position come into contact with the second surface on the downstream side in the transport direction from the second upstream contact surface. Has a second downstream contact surface
The distance from the cam axis to the center of the first upstream contact surface in the axial direction is D1 uc.
The distance from the cam axis to the end of the first upstream contact surface in the axial direction is D1ue.
The distance from the cam axis to the center of the second upstream contact surface in the axial direction is D2uc.
The distance from the cam axis to the end of the second upstream contact surface in the axial direction is D2ue,
The distance from the cam axis to the center of the first downstream contact surface in the axial direction is D1dc.
The distance from the cam axis to the end of the first downstream contact surface in the axial direction is D1de.
The distance from the cam axis to the center of the second downstream contact surface in the axial direction is D2dc.
The distance from the cam axis to the end of the second downstream contact surface in the axial direction is D2de.
D2uc-D2ue is different from D1uc-D1ue.
D2dc-D2de is different from D1dc-D1de.
The fixing device D2dc-D2de is different from D2uc-D2ue. The cam has a first cam surface and a second cam surface arranged around the cam axis.
The first upstream contact surface and the first downstream contact surface are located on the first cam surface.
The fixing device according to claim 5, wherein the second upstream contact surface and the second downstream contact surface are located on the second cam surface. The cam
A shaft extending along the cam axis and
A first protruding portion that protrudes from the shaft in a direction orthogonal to the cam axis and has the first upstream contact surface at the tip thereof.
A second protruding portion that protrudes from the shaft in a direction orthogonal to the cam axis and has the first downstream contact surface at the tip thereof.
A third protruding portion that protrudes from the shaft in a direction orthogonal to the cam axis and has the second upstream contact surface at the tip thereof.
The fixing device according to claim 5, further comprising a fourth protruding portion that protrudes from the shaft in a direction orthogonal to the cam axis and has the second downstream contact surface at the tip thereof. The fixing device according to any one of claims 5 to 7, further comprising a motor for rotating the cam. The width of the endless belt and the nip surface of the roller in the transport direction is
When the cam is in the first rotation position, the width of the central portion in the axial direction is N1c, and the width of the end portion in the axial direction is N1e.
When the cam is in the second rotation position, the width of the central portion in the axial direction is N2c, and the width of the end portion in the axial direction is N2e.
N1c> N1e
And N2c <N2e
The fixing device according to any one of claims 5 to 8, wherein the fixing device satisfies. With an endless belt
A pressure pad having a first surface in contact with the inner peripheral surface of the endless belt and a second surface located on the opposite side of the first surface.
A roller that sandwiches the endless belt with the pressure pad and conveys the recording sheet between the endless belt and the recording sheet in the conveying direction.
An upstream pressing mechanism having a plurality of upstream pressing pins capable of pressing the second surface arranged in the axial direction of the roller, and an upstream pressing mechanism.
A downstream pressing mechanism arranged on the downstream side in the transport direction with respect to the upstream pressing mechanism and having a plurality of downstream pressing pins capable of pressing the second surface arranged in the axial direction of the roller.
A control device capable of moving the plurality of upstream pressing pins and the plurality of downstream pressing pins forward and backward with respect to the second surface, wherein the plurality of upstream pressing pins and the plurality of downstream pressing pins are moved. A control device that moves to one state and a second state different from the first state is provided.
One that is parallel to the plane passing through both ends of the first surface in the transport direction and is on the side opposite to the axis of the roller with respect to the tips of the plurality of upstream pressing pins and the plurality of downstream pressing pins. With the plane of
In the first state, the distance from the reference plane to the tip of the upstream pressing pin at the center in the axial direction is D1 uc.
In the first state, the distance from the reference plane to the tip of the upstream pressing pin at the end in the axial direction is D1ue.
In the second state, the distance from the reference plane to the tip of the upstream pressing pin at the center in the axial direction is D2uc.
In the second state, the distance from the reference plane to the tip of the upstream pressing pin at the end in the axial direction is D2ue.
In the first state, the distance from the reference plane to the tip of the downstream pressing pin at the center in the axial direction is D1dc.
In the first state, the distance from the reference plane to the tip of the downstream pressing pin at the end in the axial direction is D1de.
In the second state, the distance from the reference plane to the tip of the downstream pressing pin at the center in the axial direction is D2dc.
In the second state, the distance from the reference plane to the tip of the downstream pressing pin at the end in the axial direction is D2de.
D2uc-D2ue is different from D1uc-D1ue.
D2dc-D2de is different from D1dc-D1de.
The fixing device D2dc-D2de is different from D2uc-D2ue. The width of the endless belt and the nip surface of the roller in the transport direction is
In the first state, the width of the central portion in the axial direction is N1c, and the width of the end portion in the axial direction is N1e.
In the second state, the width of the central portion in the axial direction is N2c, and the width of the end portion in the axial direction is N2e.
N1c> N1e
And N2c <N2e
The fixing device according to claim 10, wherein the fixing device satisfies. The fixing device according to any one of claims 1 to 11, wherein the D1dc-D1de is different from the D1uc-D1ue. The fixing device according to any one of claims 1 to 12, wherein D2uc-D2ue> D1uc-D1ue. The fixing device according to any one of claims 1 to 12, wherein D2uc-D2ue <D1uc-D1ue. The fixing device according to any one of claims 1 to 12, wherein D2dc-D2de> D1dc-D1de. The fixing device according to any one of claims 1 to 12, wherein D2dc-D2de <D1dc-D1de. The fixing device according to any one of claims 1 to 12, wherein D2dc-D2de> D2uc-D2ue. The fixing device according to any one of claims 1 to 12, wherein D2dc-D2de <D2uc-D2ue. The fixing device according to any one of claims 1 to 12, wherein D1dc-D1de> D1uc-D1ue. The fixing device according to any one of claims 1 to 12, wherein D1dc-D1de <D1uc-D1ue.

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