JP2003076202A - Fixing device, and image forming apparatus having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the coating of a releasing agent on the fixing belt of a fixing device in which a fixing member consisting of the fixing belt is wound around a plurality of guide rollers, and a pressurizing member consisting of a pressure roller is pressed to the fixing belt. SOLUTION: A recording material P which has passed through a nip part N between the fixing member 14 consisting of the fixing belt and the pressurizing member 15 consisting of the pressure roller is adhered to the fixing member 14 and is transported as it is. After the recording material P has passed through between the fixing member 14 and the transport roller 18, the recording material P is peeled from the fixing member 14, and the surface linear velocity of the transport roller 18 and the surface linear velocity of the fixing member 14 are made different.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fixing an unfixed toner image carried on a recording material, and an image forming apparatus having the fixing device.

[0002]

2. Description of the Related Art In an image forming apparatus constructed as an electronic copying machine, a printer, a facsimile, or a composite machine having at least these two functions, an unfixed toner image carried on a recording material is subjected to heat and pressure. A fixing device that fixes by action is used. As such a fixing device, a pressure member is brought into pressure contact with a fixing member, and a recording material carrying an unfixed toner image is oriented so that the toner image is in contact with the fixing member, and a pressure contact portion between the fixing member and the pressure member is provided. That is, there is known a device of a type that passes through the nip portion.

In the case of this fixing device, when the recording material passes through the nip portion between the fixing member and the pressure member, the phenomenon in which the high temperature toner migrates to the surface of the fixing member, that is, the purpose of preventing high temperature offset, A large amount of a release agent made of, for example, low-viscosity silicone oil is applied to the surface of the fixing member. In the case of a color image forming apparatus, a low melting point toner is used because it is necessary to sufficiently melt the toner at the time of fixing the toner image in order to improve color reproducibility and glossiness of the image. Since a low melting point toner is likely to be offset at high temperature, it is necessary to apply a particularly large amount of silicone oil to the surface of the fixing member. However, if a large amount of silicone oil is applied to the surface of the fixing member in this way,
This may adhere to the recording material, or a large amount of silicone oil may be used, which may cause spillage.

Therefore, the surface linear velocity of the rotating fixing member,
It is conceivable that the speed of the recording material conveyed through these nip portions and the linear speed of the surface of the fixing member are made different from each other by making the surface velocities of the rotating pressure members different from each other. According to this structure, since a shearing force acts between the toner on the recording material and the surface of the fixing member,
It is possible to efficiently separate the toner image from the surface of the fixing member, prevent the offset of the transfer of the toner to the surface of the fixing member, and prevent the recording material from winding around the surface of the fixing member. Become. As a result, the release agent is not applied to the surface of the fixing member, or the application amount thereof can be reduced. However, since the toner existing in the nip portion between the fixing member and the pressure member has a high temperature and is in a molten state or a softened state, the difference between the speed of the recording material and the linear velocity on the surface of the fixing member is in the nip portion. However, if the value is set to a large value, for example, 1% or more of the surface linear velocity of the fixing member, the disadvantage that the toner in the nip portion shifts with respect to the recording material and the toner image is disturbed is unavoidable. Therefore, if the difference between the linear velocity of the surface of the fixing member and the speed of the recording material is set to be smaller than the above value, then the offset prevention effect and the recording material wrapping prevention effect become insufficient.

[0005]

SUMMARY OF THE INVENTION The present invention has been made based on the above recognition, and it is possible to prevent offset even if the release agent is not applied to the surface of the fixing member or the application amount is reduced. A first object is to provide a fixing device capable of preventing the recording material from being wound around the fixing member, and a second object is to provide an image forming apparatus including the fixing device.

[0006]

In order to achieve the first object, the present invention is a recording material having a toner image to be fixed in a nip portion between a rotating fixing member and a rotating pressure member. The toner image in the direction of coming into contact with the fixing member, pressurizing and heating the toner image in the nip portion to melt the toner of the toner image, and fix the recording material exiting the nip portion. The temperature of the toner is lowered while being conveyed in close contact with the surface of the member, then the recording material is passed through the fixing member and the pressure contact portion of the rotating conveying means, and the recording material passing through the pressure contact portion is fixed as the fixing member. In a fixing device separated from the above, there is proposed a fixing device characterized in that the surface linear velocity of the fixing member and the surface linear velocity of the conveying means are made different (Claim 1).

In this case, it is advantageous that the fixing member is constructed as a fixing belt which is wound around a guide roller and driven to rotate, and the surface linear velocity of the conveying means is periodically changed. ).

Further, in the fixing device according to claim 1 or 2, the conveying means is constituted by a conveying roller having a core shaft and a porous resin layer provided around the core shaft. Is advantageous (claim 3).

Further, in the fixing device according to any one of claims 1 to 3, it is advantageous that the conveying means has a surface layer made of a silicone rubber layer (claim 4).

Further, in order to achieve the second object, the present invention proposes an image forming apparatus comprising the fixing device according to any one of claims 1 to 4 (claim 5). .

At this time, it is advantageous that the toner of the toner image fixed by the fixing device contains at least a binder resin, a colorant and a wax (claim 6).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view showing a part of a color printer which is an example of an image forming apparatus. The image forming apparatus shown here is an image forming unit 1 for forming a toner image on a recording material.
And a fixing device 2 for fixing the toner image on the recording material. First, the outline of the image forming means 1 will be clarified.

The image forming means 1 shown in FIG. 1 includes first to fourth image bearing members 3Y and 3 which are formed as drum-shaped photosensitive members.
M, 3C, and 3BK, and a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image are formed on the respective image carriers. A transfer belt 4 is arranged so as to face the first to fourth image carriers 3Y to 3BK, and the transfer belt 4 includes a driving roller 5 and a driven roller 6.
And is driven to rotate in the direction of arrow A.

First to fourth image carriers 3Y, 3M, 3
Since the structure for forming a toner image on C and 3BK is substantially the same as the structure for forming a toner image, only the structure for forming a toner image on the first image carrier 3Y will be described. This image carrier 3
Y is rotationally driven in the clockwise direction in FIG. 1, and at this time, the surface of the image carrier is uniformly charged to a predetermined polarity by the charging roller 7. Then, the light-modulated laser beam L emitted from the laser writing unit 8 is applied to the charged surface. As a result, an electrostatic latent image is formed on the image carrier 3Y, and the electrostatic latent image is visualized by the developing device 9 as a yellow toner image.

On the other hand, a recording material P made of, for example, a transfer paper or a resin sheet or a resin film is fed from a paper feeding unit (not shown), and the recording material P is, as shown by an arrow B, an image carrier. It is fed between 3Y and the transfer belt 4, carried on the transfer belt 4, and conveyed. A transfer roller 10 is disposed at a position substantially opposite to the image carrier 3Y with the transfer belt 4 interposed therebetween, and a voltage having a polarity opposite to the charging polarity of the toner on the image carrier 3Y is applied to the transfer roller 10. ,
As a result, the yellow toner image on the image carrier 3Y is transferred onto the recording material P. The untransferred toner left on the image carrier 3Y without being transferred to the recording material P is the cleaning device 1.
Removed by 1.

In exactly the same manner, a magenta toner image, a cyan toner image and a black toner image are formed on the second to fourth image carriers 3M, 3C and 3BK, respectively, and these toner images are converted into yellow toner images. Transferred recording material P
The images are transferred one on top of the other.

The recording material P carrying the unfixed toner images of four colors as described above is fed to the fixing device 2 as shown by an arrow C, and at that time, the toner image is fixed on the recording material P. . The recording material that has passed through the fixing device 2 is conveyed in the direction of arrow D and discharged onto a paper discharge tray (not shown).

FIG. 2 is an enlarged sectional view of the fixing device 2 shown in FIG. 1. The fixing device 2 shown here has a fixing member 14 configured as an endless fixing belt. Is wound around a plurality of guide rollers, that is, two guide rollers, a first guide roller 12 and a second guide roller 13 in the example shown in FIG. In addition, the fixing member 14
The surface of the pressure member 15 is configured as a pressure roller.
And the fixing member 14 and the pressing member 15 are pressed to form the nip portion N. In the fixing device shown in FIG. 2, the pressure member 15 is in pressure contact with the first guide roller 12 via the fixing member 14.

When the first guide roller 12 or the second guide roller 13 or both guide rollers 12 and 13 are rotationally driven by a driving device (not shown), the fixing member 14 composed of a fixing belt rotates in the direction of arrow E. When driven, the first and second guide rollers 12 and 13 rotate in the directions indicated by the arrows. The pressure member 15 is the fixing member 1.
Rotate in the direction of the arrow while being pressed against 4. That is, the pressurizing member 15 rotates at the contact portion with the fixing member 14 in a direction of moving in the same direction as the surface moving direction of the fixing member 14. The second guide roller 13 serves as a tension roller that applies tension to the fixing member 14 formed of a fixing belt.

A heater 16 as a heat source for heating the fixing member 14 is arranged inside the first guide roller 12, and the surface of the fixing member 14 is an example of a sensor for detecting the temperature of the fixing member. The thermistor 17 is arranged. The temperature of the fixing member surface is detected by the thermistor 17, and a temperature control circuit (not shown) causes the thermistor 17 to operate.
The heater 16 is controlled to be turned on and off based on the temperature detected by, and the surface temperature of the fixing member 14 is maintained within a predetermined range suitable for fixing the toner image. In the illustrated example, the thermistor 1
The fixing member 7 is installed at the center of the fixing member 14 in the width direction, and is attached at a position of about 90 ° upstream from the center of the nip portion N between the fixing member 14 and the pressing member 15 in the moving direction of the fixing member surface. ing. In this example, a halogen heater is used as the heater 16.

In the illustrated example, the fixing member 14 is wound around the two rollers of the first guide roller 12 and the second guide roller 13, but the fixing member 1 composed of a fixing belt.
It is also possible to configure 4 to be stretched over three or more rollers.

Further, rather than the nip portion N, the fixing member 1
A transport roller 1 which is an example of a transport unit that applies a transport force to the recording material on the surface of the fixing member on the downstream side in the surface movement direction of 4.
8 is brought into pressure contact, and the conveying roller 18 is rotationally driven in the direction of the arrow by a driving device (not shown). That is, the transport roller 18 is rotationally driven in a direction in which it moves in the same direction as the surface moving direction of the fixing member 14 at the contact portion with the fixing member 14. In the example shown in FIG. 2, the transport roller 18 is in pressure contact with the second guide roller 13 via the fixing member 14 which is a fixing belt.

The recording material P carrying the unfixed toner image T is
The toner image T is conveyed to the fixing device 2 as indicated by an arrow C, enters the nip portion N between the fixing member 14 and the pressing member 15 in the direction of contacting the fixing member 14, and passes through the nip portion N. At this time, pressure is applied to the toner image T and heat is applied to heat the toner, and the toner is melted. The recording material P that has passed through the nip portion N is conveyed by the fixing member 14 while being in close contact with the surface of the fixing member 14. In this way, the toner image is fixed on the recording material P.

Subsequently, this recording material is transferred to the conveying roller 18
And the recording material P is sent to the pressure contact portion between the fixing member 14 and the fixing member 14, and the recording material P is separated from the fixing member 14 when passing through the pressure contact portion. As described above, the recording material P passes through the nip portion N between the fixing member 14 and the pressing member 15, and then the fixing member 14
The toner of the toner image on the recording material is cooled by the temperature decrease of the fixing member itself and the viscosity is increased in this conveying process while being in close contact with the surface of the fixing member 14 and the conveying roller. , Glass transition state. The transport roller 18 applies a transport force to the recording material P from the back surface of the recording material P.

As described above, in the fixing device of this embodiment, the recording material carrying the toner image to be fixed is provided in the nip portion between the rotating fixing member and the rotating pressure member, and the toner image is used as the fixing member. The toner image of the toner image is melted by pressing and heating the toner image in the nip portion, and the recording material exiting the nip portion is brought into close contact with the surface of the fixing member and conveyed. While lowering the temperature of the toner,
Next, the recording material is made to pass through the fixing member and the pressure contact portion of the rotating conveying means, and the recording material which has passed the pressure contact portion is separated from the fixing member.

Here, in the fixing device of this embodiment, the surface linear velocity of the fixing member 14 and the surface linear velocity of the conveying means (conveying roller 18 in the example shown in FIG. 2) are different from each other. . With such a configuration, the conveyance speed of the recording material P immediately before being peeled from the surface of the fixing member 14 and the fixing member 14
Of the toner image carried on the recording material P is promoted to be separated from the surface of the fixing member 14. As a result, even when the release agent is not applied to the surface of the fixing member 14 or the application amount of the release agent is small, the toner does not migrate to the surface of the fixing member 14 and the recording material P is fixed to the surface of the fixing member 14. The recording material P can be separated from the surface of the fixing member 14 without wrapping around the surface.

The surface linear velocity of the conveying roller 18 is determined by the fixing member 14.
When the surface linear velocity of the recording material P is lower than the surface linear velocity of the fixing member 14, the conveying speed of the recording material P, which receives the conveying force by the conveying roller 18, becomes slower than the surface linear velocity of the fixing member 14. Shear force is generated at the interface of. At that time, since the friction coefficient at the interface between the fixing member 14 and the toner is lower than the friction coefficient at the interface between the recording material P and the toner, the toner and the fixing member 14 slip with each other, and the toner and the surface of the fixing member. The adhesive force between and is reduced. In this way, the shearing force promotes the peeling of the toner from the fixing member 14, and the recording material P is peeled from the surface of the fixing member due to the rigidity of the recording material. Such a phenomenon is called self-stripping, and this self-stripping prevents offset and winding of the recording material around the surface of the fixing member.

On the contrary, when the surface linear velocity of the conveying roller 18 is faster than the surface linear velocity of the fixing member, the conveying speed of the recording material becomes faster than the surface linear velocity of the fixing member 14, and therefore, also in this case, A shearing force is generated at the interface between the toner on the recording material and the surface of the fixing member, and as described above, the offset and the winding on the surface of the fixing member are prevented, and the recording material P
Can be separated from the surface of the fixing member 14.

The recording material P is the fixing member 14 and the conveying roller 18.
The fixing process of the toner image is completed and the toner is in the glass transition state by the time of reaching the pressure contact portion with the toner, even if the difference between the conveying speed of the recording material P and the surface linear velocity of the fixing member 14 is large. The phenomenon that the image shifts with respect to the recording material P, that is, the image shift does not occur, and the problem that the image quality after fixing is deteriorated can be prevented. Therefore, the fixing member 14
The difference between the surface linear velocity of the sheet and the surface linear velocity of the conveying roller 18 can be set to a value of 1% or more of the surface linear velocity of the fixing member,
This makes it possible to prevent the offset and the winding of the recording material around the fixing member more reliably.

Further, in order to more surely cool the toner carried on the recording material P which has exited the nip portion N, the fixing member 14
And the fixing member 14 that has passed through the nip portion N between the pressure member 15 and the pressure member 15.
It is also possible to provide a cooling means for cooling the portion (1), the recording material P, or both. For example, the conveying roller 18 is formed in a hollow shape, and air is supplied to the inside thereof to keep the surface portion of the conveying roller 18 at a low temperature, and the rear surface of the recording material P is cooled by the surface, or as shown in FIG. Conveyor roller 1
8 and the nip portion N, a heat pipe 19 is brought into contact with the back surface of the fixing member portion, and the heat pipe 19 is cooled to lower the temperature of the fixing member 14, or between the conveying roller 18 and the nip portion N. It is possible to employ cooling means such as cooling the fixing member by blowing cold air flowing out from a cooling spray (not shown) onto the back surface of the fixing member portion in between.

In the fixing device described above, the transport roller 1
The drive of the transport roller 18 may be controlled so that the surface linear velocity of the transfer roller 8 is always constant. However, with such a configuration, the difference between the surface linear velocity of the fixing member 14 and the surface linear velocity of the transport roller 18 is controlled. Therefore, when the recording material P and the fixing member 14 are a fixing belt, the slack caused by the speed difference is accumulated in the recording material P and the fixing belt, and the recording material P and the fixing belt are wrinkled or slack. There is a risk that the conveyance of the recording material may become unstable due to the occurrence of the phenomenon. Therefore, in particular, the fixing member 1
When 4 is configured as a fixing belt wound around a guide roller and driven to rotate, it is preferable to periodically change the surface linear velocity of the conveying means. With this configuration, it is possible to prevent the slack from accumulating on the fixing belt and the recording material P, and to stabilize the transportability of the recording material P and the fixing belt. Such a configuration is not limited to the case where the transporting means is composed of the transporting rollers 18, but can be applied to a case where the transporting means is configured by a transporting belt as described later.

The carrying roller 18 can be constructed in any suitable form. The carrying roller 18 illustrated in FIG. 2 is, for example, a metal such as aluminum, stainless steel, or carbon steel, a hard resin, or a composite material thereof. A core shaft 30 made of a rigid body such as the above, and a rigid porous resin layer 31 fixedly provided around the core shaft 30. The porous resin layer 31 can be manufactured, for example, by filling resin molds mixed with a binder in a mold and heating the mold to burn out the binder to form pores. As the material of the resin particles, for example, polyetherimide, polyphenylene sulfide, phenol resin, etc. can be used. Since the porous resin layer including the pores has a high heat insulating property, a large amount of heat of the fixing member 14 is not taken by the transport roller 18, and the fixing member 14 is heated to start up the fixing device. At times, heat loss can be prevented, the startup time can be shortened, and energy consumption can be reduced.

Further, in the conveying roller 18 shown in FIG. 2, the surface layer 32 made of a silicone rubber layer is provided on the surface of the porous resin layer 31. Since the silicone rubber layer has a high coefficient of friction, it prevents slipping between the conveying roller 18 and the recording material P, reliably conveys the conveying force of the conveying roller 18 to the recording material P, and the toner on the recording material and the fixing member. It is possible to reliably generate a shearing force between the fixing member 14 and 14, and to prevent the offset and the winding of the recording material around the fixing member more reliably.
Such a configuration can also be applied when the conveying means is composed of something other than a conveying roller. The conveying means has a surface layer made of a silicone rubber layer.

The other constituent elements of the fixing device 2 shown in FIG. 2 can be made of appropriate materials, and various forms thereof can be adopted, but one example is as follows.

The first guide roller 12 can be constructed as a hollow metal cylindrical thin roller made of, for example, aluminum, carbon steel, stainless steel or the like. The pressure member 15 configured as a pressure roller includes, for example, a cored bar 20, an elastic heat-insulating foam layer 21 provided around the core bar 20, and a separation layer provided around the foam layer 21. The mold layer 22 is made of heat-resistant foamed silicone rubber, and the mold release layer 22 is made of P.
FA tubes can be used. Further, as the second guide roller 13, for example, a roller provided with a heat-insulating foam layer around the cored bar can be used. As the foam layer, for example, heat resistant foamed silicone rubber can be used.

As the base material of the fixing member 14 composed of the fixing belt, for example, an endless belt-shaped base material made of heat resistant resin or metal can be used. Polyimide, polyamideide, polyetherketone (PEEK) or the like can be used as the material of the heat resistant resin, and nickel, aluminum, iron or the like can be used as the material of the metal belt. The thickness is preferably 100 μm or less. Since the surface of the fixing member 14 comes into pressure contact with the recording material P and the toner, it is preferable that the surface of the fixing member 14 has releasability, and further that it has excellent heat resistance and durability. For this reason, it is desirable that the surface layer of the fixing member 14 be a heat-resistant release layer made of, for example, a fluororesin or a high release silicone rubber. The fluororesin is applied to the surface of the base material by spraying or the like, and heat-fused to form a surface release layer. The high release silicone rubber layer has a rubber hardness of 25 to
It is preferably 65 degrees (JIS A hardness meter), and the total thickness of the fixing member 14 is preferably in the range of 100 to 300 μm as a condition for obtaining good fixing property and thermal response. As another structure of the fixing member 14, when a base material made of a heat-resistant resin such as polyimide is provided with an elastic layer such as silicone rubber and a release layer such as a fluorine resin is provided thereon, the fixing is performed. It is possible to improve the transparency and the uniform fixing property of the subsequent image.

The toner of the toner image fixed by the fixing device as described above is at least a binder resin, a colorant,
It is preferable that the toner contains wax and wax, and by using such a toner, the application of the release agent to the fixing member can be omitted or the application amount of the release agent can be reduced more reliably. As the wax, carnauba, dimethylsiloxane, or the like can be used. Further, particularly in a color image forming apparatus, it is preferable not to increase the wax content in the toner so much that the glossiness and transparency of the color image after fixing are not impaired.

The configurations described above can be widely applied to various fixing devices other than those shown in FIG. For example, as shown in FIG. 3, the pressing member 15 is brought into pressure contact with the portion of the fixing member 14 that is not in contact with the guide roller 12, and the conveying means constituted by the conveying roller 18 is not in contact with the guide roller 13. It may be pressed against the fixing member 14. Moreover, as shown in FIG.
5A may be configured as an endless belt that is wound around a plurality of rollers to rotate, and similarly, the conveying means may be configured as an endless belt 18A that is wound around a plurality of rollers and driven to rotate. Further, as shown in FIG. 5, the fixing member 14A is formed into a drum shape that is driven to rotate in the arrow direction, and the pressing member 15 that rotates in the arrow direction is provided on the peripheral surface thereof.
For example, the fixing member 14A is heated by the heater 16A while being brought into contact with the conveying means configured as the conveying roller 18, and the recording material P is passed through the nip portion N between the fixing member 14A and the pressing member 15. Then, the toner of the toner image T to be fixed carried on the recording material P is melted by heating the recording material P to the fixing member 14A and the conveying roller 18.
It is also possible to cool the toner by the time it reaches the pressure contact portion with and to peel off the recording material P passing through the transport roller 18 from the surface of the fixing member 14A. Each of the above-described configurations can also be adopted in each of the fixing devices configured as described above.

Further, the present invention can be widely applied to an image forming apparatus for forming a monochrome image, an image forming apparatus for forming images on both sides of a recording material, and a fixing device used for these.

[0041]

According to the present invention, it is possible to apply no release agent to the fixing member, or to reduce the amount of the releasing agent to be extremely small. Moreover, there is a problem in that offset occurs and the recording material winds around the fixing member. Can be effectively suppressed.

[Brief description of drawings]

FIG. 1 is a schematic view showing a part of an image forming apparatus.

FIG. 2 is an enlarged sectional view of the fixing device shown in FIG.

FIG. 3 is a schematic view showing another example of a fixing device.

FIG. 4 is a schematic view showing still another example of the fixing device.

FIG. 5 is a schematic view showing still another example of a fixing device.

[Explanation of symbols]

2 fixing device 12 Guide roller 13 Guide roller 14 Fixing member 14A fixing member 15 Pressure member 15A pressure member 30 core shaft 31 Porous resin layer 32 surface N Nip part P recording material T toner image

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kiyoshi Oshima             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Jun Yura             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Jun Nakato             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Takashi Fujita             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Shigeo Kurotaka             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Hirokazu Ikegami             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F-term (reference) 2H033 AA16 BA11 BA12 BA15 BA17                       BA19 BA20 BA22 BA25 BA29                       BA31 BA32 BA58 BB18 BB23                       BB29 BB30 BB37 BB38 CA07                       CA45                 3F053 AA10 AA13 LA02 LA06 LB01                 3J103 AA02 AA51 BA02 BA41 BA43                       FA04 FA18 FA20 GA02 GA58                       HA12 HA53 HA54

Claims (6)

[Claims] 1. A recording material carrying a toner image to be fixed is passed through a nip portion between a rotating fixing member and a rotating pressure member in such a direction that the toner image is in contact with the fixing member, and the nip is provided. Portion of the toner image is pressed and heated to melt the toner of the toner image, and the recording material exiting the nip portion is brought into close contact with the surface of the fixing member to lower the temperature of the toner while being conveyed. A fixing device for allowing the recording material to pass through the pressure contact portion of the rotating conveying means with the fixing member, and separating the recording material passing through the pressure contact portion from the fixing member, the surface linear velocity of the fixing member and the conveying means. The fixing device is characterized in that the surface linear velocity of the is different. 2. The fixing device according to claim 1, wherein the fixing member is configured as a fixing belt wound around a guide roller and driven to rotate, and the surface linear velocity of the conveying unit is periodically changed. 3. The fixing device according to claim 1, wherein the transport unit is configured by a transport roller having a core shaft and a porous resin layer provided around the core shaft. 4. The fixing device according to claim 1, wherein the conveying unit includes a surface layer made of a silicone rubber layer. 5. An image forming apparatus comprising the fixing device according to claim 1. 6. The image forming apparatus according to claim 5, wherein the toner of the toner image fixed by the fixing device contains at least a binder resin, a colorant, and a wax.