JP2013182190A - Fixation device and image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixation device and an image formation apparatus capable of improving separability of a recording medium from a fixation member.SOLUTION: A fixation device includes: a flexible endless fixation belt 21; a heater 25 for heating the fixation belt 21; a pressure roller 31 pressingly making contact with the fixation belt 21; a nip formation member 26 included in the fixation belt 21 and pressing the fixation belt 21 onto the pressure roller 31 to form a nip part. The nip formation member 26 is composed of a plurality of members divided at least into two by a division line orthogonal to a travel direction of the fixation belt. A member on a nip part downstream side has physical properties for reducing at least one of surface pressure and temperature at a contact surface with the pressure roller 31 in comparison with the other members.

Description

  The present invention relates to a fixing device and an image forming apparatus, and more particularly, to a fixing device and an image forming apparatus with improved separation of a recording medium after image formation from the fixing device.

Conventionally, an image forming apparatus to which electrophotography is applied is known.
In this image forming apparatus, an electrostatic latent image is formed on the surface of a photosensitive drum as an image carrier, the latent image is developed with toner as a developer, transferred to a recording medium in a transfer device, An image is formed by fixing on a recording medium.
The fixing device sandwiches a recording medium between a fixing member and a pressure member (nip portion) arranged opposite to each other, applies heat and pressure to the recording medium and the toner image transferred onto the recording medium, and applies toner to the recording medium. Various types of fixing devices have already been proposed for fixing an image.

A known belt-type fixing device includes a fixing belt that is a fixing member wound between a heating roller that includes a heater serving as a heat source and a fixing roller having a rubber layer on the surface, and a pressure member. A pressure roller is disposed to face the fixing roller, and a nip portion is formed by the fixing belt and the pressure roller (for example, see Patent Document 1).
Also, a fixing device in which the fixing roller is omitted has already been proposed (see, for example, Patent Document 2).

That is, Patent Document 2 discloses a fixing device that includes a fixing belt in which a metal pipe including a heater is disposed on an inner peripheral surface, and a pressure roller that presses against the fixing belt to form a nip portion. Yes.
According to this configuration, the fixing belt can be heated uniformly and efficiently, and the warm-up time and the first print time can be shortened.

However, the fixing device disclosed in Patent Document 1 has a problem that the heat capacity of the fixing device increases and the warm-up time increases.
Further, even in the fixing device disclosed in Patent Document 2, the metal pipe also has a considerable heat capacity, so that not only the warm-up time is lengthened but also the driving force of the fixing belt is increased.

Further, in the fixing device disclosed in Patent Document 2, since there are less restrictions on the travel of the fixing belt, the fixing belt bends at the nip exit and the curvature decreases, so that the recording medium can be separated from the fixing belt. The problem of deterioration arises. In particular, when thin paper is used as a recording medium in a high humidity environment, there is a problem that paper jam is likely to occur.
In addition, a fixing device in which a metal pipe is omitted by providing a holding member that holds both ends of the fixing belt and restricting the traveling locus of the fixing belt has already been proposed. However, the driving force of the fixing belt increases. Cannot be solved.

  The present invention has been made in view of the above problems, and provides a fixing device and an image forming apparatus capable of improving the separation property of a recording medium from a fixing member without increasing the driving power of the fixing belt. With the goal.

  A fixing device according to the present invention includes an endless fixing member having flexibility, a heat source for heating the fixing member, a pressure member in pressure contact with the fixing member, and the fixing member enclosed in the fixing member. A nip forming member that presses against the pressure member to form a nip portion, and the nip forming member includes a plurality of members separated into at least two by a dividing line orthogonal to the traveling direction of the fixing member. The member on the downstream side of the nip portion has physical properties that reduce at least one of the surface pressure and the temperature at the contact surface with the pressure member as compared with other members.

  According to the fixing device of the present invention, at least one of the surface pressure and the temperature at the contact surface with the pressure member at the downstream side of the nip portion is reduced, so that the separation property of the recording medium after image formation from the fixing device is improved. can do.

1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention. 1 is a side view of a fixing device according to an embodiment of the present invention. It is the side view (a) and nip part internal surface pressure distribution map (b) of the nip formation member in the 1st Embodiment of this invention. It is the side view (c) of the nip formation member in the 2nd Embodiment of this invention, and the temperature distribution figure (d) in a nip part. It is sectional drawing (e) at the time of providing a gap between the 1st member and 2nd member in 1st Embodiment, and a nip part internal surface pressure distribution map (f). Sectional view (g) and nip inner surface pressure distribution diagram (h) when the boundary surface between the first member and the second member in the first embodiment is inclined with respect to the pressing direction of the pressing member. ). It is the side view (i) of the nip formation member of the 5th Embodiment of this invention, the nip part temperature distribution map (the 1) (j), and the nip part temperature distribution map (the 2) (k).

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 1, an image forming apparatus 1 in the present embodiment is configured by a tandem color pudding.
The image forming apparatus 1 has a bottle storage unit 101 above the inside of the main body, and four toner bottles 102Y, 102M, 102C, and 102K are detachably installed in the bottle storage unit 101.
These toner bottles 102Y, 102M, 102C, and 102K contain toners of corresponding colors (yellow, magenta, cyan, and black).

An intermediate transfer unit 85 is disposed below the bottle storage unit 101.
The intermediate transfer unit 85 includes an intermediate transfer belt 78, four primary transfer bias rollers 79Y, 79M, 79C, and 79K, a secondary transfer backup roller 82, a cleaning backup roller 83, a tension roller 84, and an intermediate transfer cleaning unit 80. ing. The intermediate transfer unit 85 has image forming units 4Y, 4M, 4C, and 4K that face the intermediate transfer belt 78 and correspond to the respective colors (yellow, magenta, cyan, and black).

Photosensitive drums 5Y, 5M, 5C, and 5K are disposed in the image forming units 4Y, 4M, 4C, and 4K, respectively.
Further, around each of the photosensitive drums 5Y, 5M, 5C, and 5K, a charging unit 75, a developing unit 76, a cleaning unit 77, and a charge eliminating unit (not shown) are disposed.

The photosensitive drums 5Y, 5M, 5C, and 5K have a cylindrical shape with a photosensitive layer provided on the outer peripheral surface, and are rotationally driven by a driving source (not shown).
By irradiating the outer peripheral surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K with a light beam indicated by a one-dot chain line emitted from the exposure apparatus, an original reading unit is formed on the outer peripheral surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K. The electrostatic latent image corresponding to the image information read by the user or the image information acquired from the terminal via the network is written.

  The charging unit 75 is configured to uniformly charge the outer peripheral surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K, and is a contact type that contacts and charges the photosensitive drums 5Y, 5M, 5C, and 5K. Is adopted.

The developing unit 76 supplies toner to the photosensitive drums 5Y, 5M, 5C, and 5K, and the supplied toner adheres to the electrostatic latent images written on the outer peripheral surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K. Thus, the electrostatic latent images on the photosensitive drums 5Y, 5M, 5C, and 5K are visualized as toner images.
For the photosensitive drums 5Y, 5M, 5C, and 5K, a non-contact type that supplies toner without contact is adopted.

  The cleaning unit 77 removes residual toner adhering to the outer peripheral surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K, and brings a brush into contact with the outer peripheral surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K. A brush contact type is adopted.

  The intermediate transfer belt 78 is stretched and supported by the secondary transfer backup roller 82, the cleaning backup roller 83, and the tension roller 84, and moves endlessly in the direction of the arrow shown in FIG.

  The intermediate transfer belt 78 is constituted by an endless belt formed with a resin film or rubber as a base so that a toner image formed on the photosensitive drums 5Y, 5M, 5C, and 5K is transferred. It has become.

  Each of the photosensitive drums 5Y, 5M, 5C, and 5K is formed on each of the photosensitive drums 5Y, 5M, 5C, and 5K by an image forming process including a charging process, an exposure process, a developing process, a primary transfer process, and a cleaning process. Images are formed.

The primary transfer bias rollers 79Y, 79M, 79C, and 79K respectively sandwich the intermediate transfer belt 78 with the photosensitive drums 5Y, 5M, 5C, and 5K to form primary transfer nips.
Further, a transfer bias having a polarity opposite to the polarity of the toner is applied to the primary transfer bias rollers 79Y, 79M, 79C, and 79K.

  Next, the image forming process will be described.

  First, in the charging process, the photosensitive drums 5Y, 5M, 5C, and 5K are rotated in the clockwise direction in FIG. Uniformly charged.

  In the exposure step, electrostatic latent images corresponding to the respective colors are formed on the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K by exposure scanning that irradiates the laser light L emitted from the exposure unit 3.

  In the developing process, the electrostatic latent images on the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K are developed at positions facing the developing unit 76, and toner images of respective colors are formed.

In the primary transfer process, toner images on the photosensitive drums 5Y, 5M, 5C, and 5K are transferred onto the intermediate transfer belt 78 at positions facing the intermediate transfer belt 78 and the primary transfer bias rollers 79Y, 79M, 79C, and 79K. Transcribed.
At this time, a slight amount of untransferred toner remains on the photosensitive drums 5Y, 5M, 5C, and 5K.

  In the cleaning step, untransferred toner remaining on the photosensitive drums 5Y, 5M, 5C, and 5K is mechanically collected by the cleaning blade of the cleaning unit 77 at a position facing the cleaning unit 77.

  Then, the residual potential on the photoconductive drums 5Y, 5M, 5C, and 5K is removed in a static elimination unit (not shown), and the image forming process ends.

  The toner images of the respective colors formed on the respective photoconductive drums through the image forming process are transferred onto the intermediate transfer belt 78 so as to form a color image on the intermediate transfer belt 78.

  Next, the transfer process will be described.

  The intermediate transfer belt 78 travels in the direction of the arrow in FIG. 1 and sequentially passes through the primary transfer nips of the primary transfer bias rollers 79Y, 79M, 79C, and 79K. As a result, the toner images of the respective colors on the photosensitive drums 5Y, 5M, 5C, and 5K are superimposed on the intermediate transfer belt 78 and primarily transferred.

The intermediate transfer belt 78 reaches a position facing the secondary transfer roller 89 in a state where the toner images of the respective colors are transferred in an overlapping manner.
At this position, the secondary transfer backup roller 82 sandwiches the intermediate transfer belt 78 between the secondary transfer roller 89 and forms a secondary transfer nip portion (hereinafter referred to as “nip portion”).

The four color toner images formed on the intermediate transfer belt 78 are transferred onto the recording medium P at the nip portion. At this time, untransferred toner that has not been transferred to the recording medium P remains on the intermediate transfer belt 78.
Thereafter, the untransferred toner on the intermediate transfer belt 78 is collected in the intermediate transfer cleaning unit 80. This completes the transfer process.

  Next, the image forming process will be described.

The recording medium P is conveyed from the paper supply unit 12 disposed below the image forming apparatus 1 to the position of the secondary transfer nip via the paper supply roller 97, the registration roller pair 98, and the like.
A plurality of recording media P such as transfer paper are stored in the paper supply unit 12 in a stacked manner. When the paper supply roller 97 is driven to rotate counterclockwise in FIG. The sheet is fed toward the gap between the registration roller pair 98.

The recording medium P conveyed to the registration roller pair 98 is temporarily stopped at the position of the roller nip of the registration roller pair 98 that has stopped rotating.
The registration roller pair 98 is rotationally driven in time with the color image on the intermediate transfer belt 78, and the recording medium P is conveyed toward the nip portion. In this way, a desired color image is transferred onto the recording medium P.

  Thereafter, the recording medium P is conveyed to the position of the fixing device 20, and the color image transferred to the surface is fixed on the recording medium P by pressing and heating by the fixing belt 21 and the pressure roller 31. The

Thereafter, the recording medium P is discharged out of the apparatus through a pair of paper discharge rollers 99.
The recording medium P discharged out of the apparatus by the discharge roller pair 99 is sequentially stacked on the stack unit 100 as an output image. Thereby, the image forming process is completed.

The image forming apparatus 1 includes a main body control unit and an operation input unit (not shown).
The main body control unit is constituted by a microcomputer including a CPU, ROM, RAM, I / O interface, and the like, and a program stored in advance in the ROM is executed by the CPU.

The main body control unit is connected to the operation input unit and various sensors and motors provided in the image forming apparatus 1.
The main body control unit is configured based on the detection signals input from various sensors. In addition, the power supply control for the heater 25 is executed.

  The operation input unit is provided in the main body of the image forming apparatus 1 and has various keys such as a numeric keypad and a print start key and various displays, and outputs input signals input through the various keys to the main body control unit. It is supposed to be.

  In addition, when a FAX tray is installed and data representing an image by a FAX signal is received via a telephone line, the recording medium on which the image is fixed may be conveyed to the FAX tray.

Next, the configuration and operation of the fixing device 20 according to the present invention will be described in detail.
FIG. 2 is a side view of the fixing device.

  The fixing device 20 forms a secondary transfer nip by pressing a fixing belt 21 as a fixing member, a heater 25 as a heat source, a pressure roller 31 as a pressure member, and the pressure belt 31 against the pressure roller 31. The nip forming member 26 includes a nip forming member 26 and a holding member 23 for holding the nip forming member 26.

  The fixing belt 21 is a thin endless belt having flexibility, and rotates in the direction of an arrow X (counterclockwise) in FIG. The fixing belt 21 has a configuration in which an elastic layer and a release layer are sequentially laminated on a base material, and the thickness is set to 1 millimeter (mm) or less.

The base material is made of a metal such as nickel or stainless steel or a resin such as polyimide, and has a thickness of 20 to 70 micrometers (μm).
The elastic layer is made of rubber such as silicone rubber, foamable silicone rubber, or fluororubber, and has a thickness of 100 to 300 micrometers.
The release layer prevents fine irregularities from being formed on the surface of the fixing belt 21 at the nip portion, and suppresses the generation of a crushed skin image by uniformly transferring heat to the toner on the recording medium P. belongs to.

The release layer is made of a resin such as PFA (tetrafluoroethylene bar fluoroalkyl vinyl ether copolymer resin), PTFE (tetrafluoroethylene resin), polyimide, polyetherimide, PES (polyethersulfide), and the like. The thickness is 5 to 50 micrometers.
The release layer is for ensuring releasability with respect to the toner image.

  The diameter of the fixing belt 21 is set to 15 to 200 mm, but is 30 mm in this embodiment.

Inside the fixing belt 21, a heater 25, a nip forming member 26, and a holding member 23 are installed.
The fixing belt 21 is pressed against the pressure roller 31 by the nip forming member 26 to form a secondary transfer nip portion.
In addition, it is desirable that the inner circumference of the fixing belt 21 be coated with a coating that easily absorbs radiant heat from the heater 25 and has excellent slidability.

The heater 25 is a halogen heater or a carbon heater, and both ends thereof are fixed to the side plate of the fixing device 20.
The heater 25 generates heat by the electric power controlled by the main body control unit, and heats the fixing belt 21 and the toner image.

The power supplied to the heater 25 is controlled by the main body control unit so that the surface temperature of the fixing belt 21 detected by the temperature sensor becomes a predetermined fixing temperature.
In addition, by directly heating the fixing belt 21 with the heater 25, the heat capacity of the member to be heated is reduced, thereby shortening the warm-up time and saving energy.

The pressure roller 31 has a diameter of 25 to 30 millimeters and a structure in which an elastic layer is formed on a hollow or solid cored bar.
The elastic layer of the pressure roller 31 is made of rubber such as silicone rubber, foamable silicone rubber, or fluorine rubber. The surface of the elastic layer may be covered with a release layer such as PFA or PTFE.

The pressure roller 31 forms a nip portion with the fixing belt 21. The pressure roller 31 is rotationally driven in the direction of arrow Y (clockwise) in FIG. 2 by a drive mechanism (not shown).
Further, both end portions of the pressure roller 31 are rotatably supported by the side plates of the fixing device 20. When the core bar is hollow, a heat source such as a halogen heater may be installed inside.

The nip forming member 26 presses the fixing belt 31 against the pressure roller 31 over the entire width direction.
It is desirable that the pressing surface of the nip forming member 26 has a concave groove shape having the same curvature as the pressure roller 31 or a curvature larger than the thickness of the fixing belt 31, and the fixing belt 31 is driven by the pressure roller 31. It has become.
Since the nip forming member 26 has a concave groove shape and is a thick member, it is desirable that the nip forming member 26 be a resin molded product such as a heat-resistant polyamideimide or a liquid crystal polymer.

The holding member 23 is a member for holding the nip forming member 26, and its end is fixed to the side plate of the fixing device 20.
The material is preferably stainless steel, steel, ceramic or the like having a high mechanical strength, and the shape is preferably a straight bar shape or U-shape having a large secondary moment of section.
The holding member 23 prevents the nip forming member 26 from being greatly deformed by the pressure of the pressure roller 31.

  The nip forming member 26 that is a feature of the present invention will be described below.

[First Embodiment]
FIG. 3 is a side view (a) and a nip portion inner surface pressure distribution diagram (b) of the nip forming member in the first embodiment.
As shown in the side view (a), the nip forming member 26 includes a first member 261 and a second member 262 that are divided into two by a dividing line orthogonal to the traveling direction of the fixing belt. Note that the number of divisions is not limited to two.

A housing 24 is attached to the support member 23, and the two divided members 261 and 262 are integrally held.
Then, the hardness of the first member 261 arranged on the upstream side of the nip part is made larger than the hardness of the second member 262 arranged on the downstream side of the nip part.
The nip forming member 26 is preferably made of LCP (liquid crystal polymer) having excellent heat resistance. In this embodiment, the Rockwell hardness expressed by the R scale of the second member 262 is the R scale of the first member 261. 0.58 times the Rockwell hardness expressed by

In the nip portion internal pressure distribution diagram (b), the solid line indicates the internal pressure distribution when divided into two by the widthwise dividing line, and the broken line indicates the internal pressure distribution in the case of the conventional integrated type.
That is, the inner pressure is reduced by dividing the nip forming member into two parts and reducing the hardness on the downstream side of the nip.
Therefore, the pressing of the fixing belt 21 against the recording medium P is also reduced, and the separation property between the fixing belt 21 and the recording medium P at the nip exit is improved.

[Second Embodiment]
FIG. 4 is a side view (c) and a temperature distribution diagram (d) in the nip portion of the nip forming member in the second embodiment.
As shown in the side view (c), the nip forming member 26 includes a third member 263 and a fourth member 264 that are divided into two by a dividing line in the width direction of the fixing belt. Note that the number of divisions is not limited to two.

A housing 24 is attached to the holding member 23, and the two divided members 261 and 262 are integrally held.
Then, the thermal conductivity of the fourth member 264 arranged on the downstream side of the nip part is made larger than the thermal conductivity of the third member 263 arranged on the upstream side of the nip part.
The nip forming member 26 is preferably made of LCP (liquid crystal polymer) having excellent heat resistance.

  In the present embodiment, the LCP is used as it is as the third member 263, the fourth member 264 is obtained by adding a heat conductive filler to the LCP, and the thermal conductivity of the fourth member 264 is the third member. The thermal conductivity of H.263 was 1.4 times.

In the temperature distribution diagram (d) in the nip portion, the solid line shows the internal pressure distribution when divided into two in the width direction, and the broken line shows the internal pressure distribution in the case of the conventional integrated type.
That is, by dividing the nip forming member into two parts and increasing the thermal conductivity of the member on the downstream side of the nip, the temperature on the downstream side of the nip portion is lowered.
Accordingly, the temperatures of the fixing belt 21 and the recording medium P are also lowered on the downstream side of the nip portion, and the separation property between the fixing belt 21 and the recording medium P at the nip outlet is improved.

[Third Embodiment]
In the third embodiment, the influence of the gap between each member when the nip forming member is divided is examined.
FIG. 5 is a cross-sectional view (e) and a nip portion internal pressure distribution diagram (f) when a gap of 0.3 mm is provided between the first member 261 and the second member 262 in the first embodiment. It is.

As can be seen from the nip inner surface pressure distribution diagram (f), if there is a gap between the first member 261 and the second member 262, a short cycle pulsation occurs in the nip inner surface pressure.
This pulsation causes a slight deflection and stress concentration in the fixing belt 21, which not only causes a jitter image but also shortens the life of the fixing belt 21.
Therefore, the first member 261 and the second member 262 need to be in close contact with each other on the inner periphery of the fixing belt 21.

[Fourth Embodiment]
In the fourth embodiment, the influence of the direction of the boundary surface when the nip forming member is divided is examined.
FIG. 6 is a cross-sectional view (g) and a nip when the boundary surface between the first member 261 and the second member 262 is inclined with respect to the pressing direction of the pressing member 31 in the first embodiment. It is a part inner surface pressure distribution map (h).
In the nip inner surface pressure distribution diagram (h), the broken line indicates the boundary surface between the first member 261 and the second member 262 applied to the pressure roller 31 as in the first embodiment (FIG. 3). The nip inner surface pressure distribution in the case of being parallel to the pressure direction is shown.

As can be seen from this nip inner surface pressure distribution diagram (h), when the boundary surface between the first member 261 and the second member 262 is inclined with respect to the pressing direction of the pressure roller 31, the nip portion downstream. The amount of decrease in the inner surface pressure of the nip portion is reduced, and the effect of dividing the nip forming member is reduced.
Therefore, it can be seen that it is desirable to separate the nip forming member 26 so that the boundary surface is parallel to the pressing direction of the pressure roller 31.

  Also in the second embodiment, when the boundary surface is slanted, the contact area between the first member and the second member increases and the temperature is easily uniformed. It is desirable to be parallel to the pressing direction.

[Fifth Embodiment]
FIG. 7 is a side view (i) of the nip forming member of the fifth embodiment, a nip temperature distribution diagram (part 1) (j), and a nip temperature distribution diagram (part 2) (k).
That is, in the present embodiment, the heat radiating member 27 is installed in the housing portion of the housing 24 for the second member 262 so that the temperature of the second member 262 is lowered.

Nip temperature distribution (No. 1) (j) is the temperature distribution when the first sheet is copied, and Nip temperature distribution (No. 2) (k) is the temperature after 100 sheets are copied continuously. Show the distribution.
In addition, a broken line is a temperature distribution at the time of using the conventional integrated member as a nip formation member.
If copying is performed continuously, the overall temperature rise is unavoidable, but by installing the heat dissipating member 27, the temperature downstream of the nip portion can be effectively lowered.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Exposure part 4Y, 4M, 4C, 4K Image forming part 5Y, 5M, 5C, 5K Photosensitive drum 12 Paper feed part 20 Fixing device 21 Fixing belt 23 Holding member 24 Case 25 Heater 26 Nip forming member 27 Radiation member 31 Pressure roller 75 Charging unit 76 Development unit 77 Cleaning unit 78 Intermediate transfer belt 79Y, 79M, 79C, 79K, Primary transfer bias roller 80 Intermediate transfer cleaning unit 82 Secondary transfer backup roller 83 Cleaning backup roller 84 Tension roller 85 Intermediate transfer unit 89 Secondary transfer roller 97 Paper feed roller 98 Registration roller pair 99 Paper discharge roller pair 100 Stack part 101 Bottle storage part 102Y, 102M, 102C, 102K Toner bottle 261 First member 262 Second member 263 Third member 264 Fourth member

JP-A-11-002982 ([0009], FIG. 1) JP 2007-334205 A ([0006], FIG. 1)

Claims (7)

An endless fixing member having flexibility;
A heat source for heating the fixing member;
A pressure member in pressure contact with the fixing member;
A nip forming member included in the fixing member and forming a nip portion by pressing the fixing member against the pressure member,
The nip forming member is composed of a plurality of members separated by at least two dividing lines perpendicular to the traveling direction of the fixing member, and the member on the downstream side of the nip portion is in contact with the pressure member as compared with other members. A fixing device having physical properties for reducing at least one of surface pressure and temperature at a contact surface.   The nip forming member has a plurality of members separated into at least two by a dividing line orthogonal to the traveling direction of the fixing member, and the member on the downstream side of the nip portion has a smaller hardness than other members. The fixing device according to claim 1.   The nip forming member includes a plurality of members separated into at least two by a dividing line orthogonal to the traveling direction of the fixing member, and the member on the downstream side of the nip portion has a higher thermal conductivity than the other members. The fixing device according to claim 1, wherein the fixing device is one.   The nip forming member includes a plurality of members separated into at least two by a dividing line orthogonal to the traveling direction of the fixing member, and the member on the downstream side of the nip portion includes a heat radiating member. The fixing device according to any one of the above.   5. The fixing device according to claim 1, wherein the plurality of members are in close contact with each other at least on a contact surface of the fixing member with the pressure member.   6. The fixing device according to claim 1, wherein boundary surfaces of the plurality of members are parallel to a pressing direction by the pressing member. An image forming apparatus including a fixing unit that performs a fixing process on a recording medium on which an image is formed in the image forming unit,
An image forming apparatus in which the fixing device according to any one of claims 1 to 6 is mounted as the fixing unit.

Images