JP2003107952A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device improved by solving a problem that the life of a fixing roller is shortened because the surface of the fixing roller is damaged by the lump of toner or paper powder when much toner or paper powder adheres to the pressing pad of a release agent coating device in the case of uniformizing a release agent dropped on the fixing roller by the pressing pad and preventing the toner or the paper powder which can not be removed perfectly by a cleaning device from adhering to a blade simultaneously in the fixing device of the image forming device. SOLUTION: This image forming device is provided with a fixing device having an oil coating device dropping oil onto the fixing roller, uniformizing it by felt and regulating it by a blade, and realizes the improvement of cleaning performance and the prolongation of the life of the fixing roller by forming the felt in the shape of a roller and switching its feed amount and its pressuring force according to environmental condition, paper thickness and the number of copies.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image having heat fixing means for fixing a non-fixed toner image by passing a recording material having an unfixed toner image between a fixing roller and a pressure roller which are in pressure contact with each other. The present invention relates to a forming apparatus, and more particularly to a color image forming apparatus having a heat fixing unit and a plurality of image forming units.

[0002]

2. Description of the Related Art FIGS. 8 and 9 show a conventional four-drum laser beam printer (image forming apparatus) having a plurality of optical scanning means.

As shown in FIG. 8, the printer is an electrophotographic photosensitive member (hereinafter referred to as "photosensitive drum") which is a latent image carrier.
Four image forming stations, which are image forming means including a developing device, are provided around the image forming device, and the image on the photosensitive drum formed by each of the image forming stations is
It is configured to be transferred to a recording material such as paper on a conveying unit that moves and passes adjacent to the photosensitive drum.

Further, as shown in FIG. 9, the photosensitive drums 1a, 1b, 1c, and 1d, 1b, 1c, and 1d, are formed on the image forming stations Pa, Pb, Pc, and Pd that form images of magenta, cyan, yellow, and black, respectively. 1d is arranged, and further, around each photosensitive drum 1a, 1b, 1c, 1d, a charger 12a, 12b, 12c, 12d, a developing device 2a, 2b, 2c, 2d, and a cleaner 4 are provided.
a, 4b, 4c, and 4d are sequentially arranged along the rotation direction of the photosensitive drum, and the transfer section 3 is arranged below each photosensitive drum.

The transfer portion 3 is provided with each image forming station P.
The transfer belt 31 and the transfer chargers 3a, 3b, 3c and 3d, which are recording material conveying means, are common to a, Pb, Pc and Pd.

In the printer (image forming apparatus) as described above, a paper feed cassette 6 as a recording material supply means shown in FIG.
The paper P supplied from No. 1 is supported on the transfer belt 31 and conveyed to each image forming station Pa, Pb, Pc, Pd, and each color formed on each photosensitive drum 1a, 1b, 1c, 1d. Toner images are sequentially transferred.

When the transfer step is completed, the paper P is separated from the transfer belt 31 and is conveyed to the fixing device 5 by a conveyor belt 62 which is a recording material guide means.

As shown in detail in FIG. 10, the fixing device 5 includes a fixing roller 51 that is rotatably arranged, a pressure roller 52 that rotates while being in pressure contact with the fixing roller 51, and a release agent supply coating. It is configured to have a release agent applying device 53 as a means and roller cleaning devices 54 and 55.

Inside the fixing roller 51 and the pressure roller 52, heaters 56 and 57 such as halogen lamps are provided, respectively.

Further, the fixing roller 51 and the pressure roller 52
Are arranged so that the thermistors 58 and 59 are in contact with each other, and heaters 56 and 57 are provided via a temperature control circuit.
The temperature of the surfaces of the fixing roller 51 and the pressure roller 52 is adjusted by controlling the voltage applied to the fixing roller 51 and the pressure roller 52.

The fixing roller 51 comprises, for example, an HTV (high temperature vulcanization type) silicone rubber layer as an elastic layer on a cored bar made of aluminum, and a fluorine rubber layer as an oil resistant layer on the outside thereof.
Further, an LTV (low temperature vulcanization type) silicone rubber layer or an RTV (room temperature vulcanization type) silicone rubber layer is provided on the outer side thereof as a release layer, and is formed to have a thickness of 2 mm and a diameter of 60 mm.

The pressure roller 52 has the same structure and a thickness of 1 m.
m, diameter 60 mm.

A cleaning device 54 and a release agent applying device 53 are attached to the fixing roller 51. The cleaning device 54 cleans the toner and the like offset on the fixing roller 51, and also releases the release agent. A silicone oil or the like, which is a release agent, is applied to the fixing roller 51 by the application device 53 to facilitate separation of the paper P from the fixing roller 51 and prevention of toner offset.

The release agent applying device 53 pumps up an oil tank 53a having a release agent such as silicone oil and oil as a release agent from the oil tank 53a by a pump or the like.
A release agent supply pipe 53b made of metal or the like to be supplied to the fixing roller 51, a pressing pad 53c for uniformizing the release agent on the fixing roller 51, and a blade 5 for controlling the amount of the release agent.
It is composed of 3d.

The release agent supply pipe 53b is the fixing roller 51.
Is provided above the fixing roller 51 and has a plurality of holes, through which a release agent is dripped onto the surface of the fixing roller 51.

The pressing pad 53c is made of a heat-resistant felt or the like, and makes the release agent dropped on the fixing roller 51 uniform.

The cleaning device 54 includes a cleaning web 54a made of a band-shaped heat-resistant nonwoven fabric, and a pressing roller 54b for pressing the cleaning web 54a against a fixing roller.
And a take-up roller 54c for unwinding a new cleaning web 54a, and a take-up roller 54d for gradually taking up the cleaning web 54a whose cleaning ability has deteriorated due to toner or the like.
In particular, the cleaning device 54 is provided on the upstream side of the thermistor 58 in the rotational direction of the fixing roller 51 so that the offset toner does not adhere to the thermistor 58 to cause detection failure in the thermistor 58.

The pressure roller 52 is also attached to the fixing roller 5
The cleaning device 55 including a cleaning web 55a, a pressing roller 55b, a winding roller 55c, a winding roller 55d, and the like similar to the cleaning device 54 of No. 1 is attached, and the toner attached to the pressure roller 52 via the fixing roller 51 is attached. Is being cleaned.

The pressure roller 52 includes a pressure roller 5
An oil removal blade 60 made of fluororubber or silicone rubber is in contact with the blade 2 in order to remove the excess release agent left on the surface 2.

In this state, when the paper P is conveyed, the fixing roller 51 and the pressure roller 52 rotate at a constant speed, the surface of the fixing roller 51 is coated with silicone oil as a release agent, and the paper P is removed. Fixing roller 51 and pressure roller 5
When passing between the two, the unfixed toner image on the surface of the paper P is melted and fixed by being pressed and heated from both the front and back sides at a substantially constant pressure and temperature, and a full-color image is formed on the paper P. .

The paper P on which the image has been fixed is separated from the pressure roller 52 by the lower separation claw 68 and is discharged to the outside of the machine.

[0022]

However, the above-mentioned conventional example has the following problems.

In the conventional fixing device, the pressing pad 53c of the releasing agent applying device 53 uniformizes the releasing agent dropped on the fixing roller 51, but at the same time, the cleaning device 54 cannot completely remove the toner. The paper dust was also prevented from adhering to the blade 53d.

If toner or paper powder adheres to the blade 53d, fluctuations in the amount of release agent applied or streaks occur, which leads to deterioration of image quality. Therefore, toner or paper powder adheres to the upstream pressing pad 53c. That was valid.

However, if a large amount of toner or paper powder adheres to the pressing pad 53c, the lump will be fixed.
The surface of No. 1 was scratched, resulting in a short life of the fixing roller 51.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus capable of preventing the surface damage of the fixing roller and improving the life of the oil felt roller. To do.

[0027]

Therefore, in the present invention, the above object is achieved by providing any one of the following image forming apparatuses (1) to (3). Is.

(1) It has a roller pair of a fixing roller and a pressure roller which are rotatably arranged while being in pressure contact with each other, and a recording material having an unfixed image is nipped and conveyed at a pressure contact portion formed by the roller pair. In an image forming apparatus having a fixing device that heat-fixes an unfixed image on the recording material, an environmental temperature detecting means for detecting an environmental temperature or a recording material thickness detecting means for detecting the thickness of the recording material is provided. , A releasing agent supplying means for supplying a releasing agent onto the surface of the fixing roller, a releasing agent uniformizing means for contacting the fixing roller and homogenizing the supplied releasing agent, and contacting the fixing roller. A release agent amount control means for controlling the release agent amount is sequentially arranged from the upstream side in the rotational direction of the fixing roller, and the release agent uniformizing means has a contact surface with the fixing roller in the rotational direction of the fixing roller. Is moved in the forward or reverse direction Rukoto can, the image forming apparatus characterized by the amount of movement is a release agent uniformizing means which can be varied by the thickness of the environmental temperature, or the recording material.

(2) A roller pair of a fixing roller and a pressure roller which are rotatably arranged while being in pressure contact with each other is provided, and a recording material having an unfixed image is nipped and conveyed at a pressure contact portion formed by the roller pair. In an image forming apparatus having a fixing device that heat-fixes an unfixed image on the recording material, an environmental temperature detecting means for detecting an environmental temperature or a recording material thickness detecting means for detecting the thickness of the recording material is provided. , A releasing agent supplying means for supplying a releasing agent onto the surface of the fixing roller, a releasing agent uniformizing means for contacting the fixing roller and homogenizing the supplied releasing agent, and contacting the fixing roller. A release agent amount control means for controlling the release agent amount is sequentially arranged from the upstream side in the rotation direction of the fixing roller, and the release agent uniformizing means has a contact surface with the fixing roller in the rotation direction of the fixing roller. Move it in the forward or reverse direction It can be an image forming apparatus, characterized in that the contact surface pressure is ambient temperature, or mold release agent uniformizing means which can be varied by the thickness of the recording material.

(3) The image forming apparatus according to (1) or (2), wherein the releasing agent uniformizing means has a heat-resistant felt or a heat-resistant non-woven fabric on the contact surface with the fixing roller.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on Examples.

(First Embodiment) A first embodiment of the present invention will be described with reference to FIG.

In FIG. 1, 5 is a fixing device.

The fixing device 5 includes a fixing roller 51 which is rotatably arranged, a pressure roller 52 which rotates while being in pressure contact with the fixing roller 51, a releasing agent applying device 53 which is a releasing agent supplying means, and a roller cleaning device. 54, 55, heater 5
6, 57, thermistors 58 and 59, an oil removing blade 60, a lower separating claw 68, and an oil leveling roller 70 which is a release agent uniformizing means.

Further, in this embodiment, the fixing device 5 is
A temperature detector 90, which is an environmental temperature detecting means, is provided.

The release agent applying device 53 is an oil tank 53.
a, a release agent (oil) supply pipe 53b, and a control blade 53d which is a release agent amount control means.

The roller cleaning devices 54 and 55 include cleaning webs 54a and 55a, pressure rollers 54b,
55b, unwinding rollers 54c, 55c, take-up roller 5
It is composed of 4d and 55d.

Oil leveling roller (means for uniformizing release agent)
The surface 70 is made of heat-resistant felt (or heat-resistant nonwoven fabric) 71, and the lower layer 72 is made of sponge rubber or the like.

In this embodiment, the oil leveling roller 70 is used, and by rotating it in the direction opposite to or in the direction of the rotation of the fixing roller 51, it is possible to make the oil uniform and to clean the toner paper powder. It was done.

In FIG. 1, the oil dropped from the supply pipe 53b is the oil leveling roller 70 and the fixing roller 5.
It is made uniform on the fixing roller 51 when passing through the nip with 1.

At the same time, toner and paper dust that cannot be completely cleaned by the cleaning device 54 also adhere to the heat-resistant felt 71 on the surface layer of the oil leveling roller 70 at this nip and are cleaned.

Since the oil leveling roller 70 is rotating in the reverse direction or the forward direction with respect to the rotation direction of the fixing roller 51, the following surface appears, and the fixing roller is more than the pressing pad 53c shown in FIG. Less damage to 51.

The rotation speed of the oil leveling roller 70 is preferably slower than the rotation speed of the fixing roller 51.

Further, the wider the nip between the oil leveling roller 70 and the fixing roller 51, the better the cleaning power. Therefore, the lower layer 72 of the oil leveling roller 70 is made of soft Si.
Rubber or sponge rubber is desirable.

With such a structure, it is possible to prevent the fixing roller 51 from being scratched by the toner and the paper powder attached to the oil leveling roller 70.

However, the offset amount of the toner to the fixing roller 51 differs depending on the copy mode and environment, and when the offset amount is large, it is more effective to enhance the cleaning power of the oil leveling roller 70.

Therefore, in this embodiment, the feed amount (movement amount) of the oil leveling roller 70 is controlled according to the environment in which the fixability is different and the toner offset amount is different.

FIG. 2 shows a block diagram of this embodiment.

Generally, when the temperature of the environment is high, the toner at the time of fixing is more likely to be melted, so that the amount of offset toner attached to the fixing roller 51 increases.

In FIG. 2, when the copy button is pressed, the ambient temperature is detected by the temperature sensor in the main body which is the ambient temperature detecting means.

Then, as shown in the graph of FIG. 3, the rotation amount (movement amount) of the oil leveling roller is determined, and the oil leveling roller 70 is rotated by the rotation amount corresponding thereto.

By doing so, in a high temperature environment where the temperature is high and the amount of offset toner is large, the oil leveling roller 70 is used.
The rotation amount of is large, the next surface appears quickly, and the cleaning power becomes large.

On the contrary, in a low temperature environment, the rotation amount of the oil leveling roller 70 is small, which leads to the improvement of the life of the oil leveling roller.

In this embodiment, the rotation amount is 0.5 mm / 10 sheets in a 20 ° C. environment, and the rotation amount is 0.
25mm / 10 sheets, rotation amount 0.7 at 30 ℃ environment
When it was set to 5 mm / 10 sheets, good cleaning property was obtained.

In the present embodiment, not only the rotation amount of the oil leveling roller 70 but also the feed amount (movement amount) is controlled at a sheet number interval of one sheet at the end of copying a certain number of sheets as shown in FIG. Also has the same effect.

That is, in a high temperature environment, the interval between the number of fed oil leveling rollers 70 is short, and in a low temperature environment the interval between the number of sheets is increased.

By doing so, the oil leveling roller 70 can be used more effectively.

Further, by further attaching a toner wiping member to the oil leveling roller 70, the life can be further extended.

For example, as shown in FIG.
0.5mm / 15 sheets in the environment, 0.5mm / in 20 ° C environment
When 10 sheets and 0.5 mm / 5 sheets in a 30 ° C. environment were used, good cleaning properties were obtained.

Further, if the pressing pressure of the oil leveling roller 70 against the fixing roller 51 is increased, the cleaning property of toner and paper powder is improved.

However, if the contact is continuously applied strongly, the damage to the fixing roller 51 will be increased.

Therefore, according to the environment in the above sequence,
It is also effective to control the pressure applied to the oil leveling roller 70 to change the contact surface pressure with the fixing roller.

That is, the pressure of the oil leveling roller 70 is increased in a high temperature environment where the offset toner amount is large, and the pressure is set low in a normal environment or a low temperature environment where the offset toner is relatively small. .

The setting of the rotation amount, the feeding number of sheets, and the pressing force differ depending on the outer diameter and material of the oil leveling roller, and are not necessarily limited to the values in this embodiment.

(Second Embodiment) FIG. 5 shows a block diagram of this embodiment.

In the fixing device of FIG. 1, this embodiment controls the feed sequence of the oil leveling roller 70 according to the type of recording material.

In general, in order to satisfy the fixing property of the recording material on the specifications, the fixing temperature and the like are set so that the recording material having a severe fixing property can be fixed.

However, if the recording material which is easy to fix is fixed under the same conditions, the toner is melted too much, and the amount of toner offset to the fixing roller 51 side at the time of fixing increases.

When the copy button is pressed in FIG. 5, the paper thickness detector 8 which is the recording material thickness detecting means shown in FIG.
At 0, the thickness of the recording material is detected.

The paper thickness detector 80 is incorporated in the registration roller 81, which enables the upper roller 81a to move up and down, and the spring member 81c81c presses the upper roller 81a toward the lower roller 81b, depending on the thickness of the recording material. Upper roller 81
a is moved up and down.

A clutch 82 is provided at one end of the upper roller 81a to magnify and transmit the vertical movement of the upper roller 81a, and a potentiometer 83 for detecting the paper thickness by the swing amount of the clutch 82 is provided at one end of the clutch 82. Installed.

The controller determines the paper thickness of the recording material based on the signal from the paper thickness detector 80. If the paper thickness is smaller than a predetermined value, the rotation amount of the oil leveling roller 70 is increased to increase the cleaning force. Can be increased.

On the contrary, when the paper thickness is thicker than the predetermined value, the amount of rotation of the oil leveling roller 70 may be small, which leads to the extension of the life of the oil leveling roller 70.

Further, as in the first embodiment, the number of feeding intervals of the oil leveling roller 70 and the fixing roller 5 are changed according to the paper thickness.
The same effect can be obtained by controlling the pressure applied to No. 1 and changing the contact surface pressure with the fixing roller 51.

(Third Embodiment) FIG. 7 shows a block diagram of this embodiment.

In the fixing device of FIG. 1, this embodiment controls the feed sequence of the oil leveling roller 70 according to the number of copies.

Generally, when the number of copies in one copy sequence is large, the release agent on the fixing roller 51 is taken away by the recording material one after another, and the toner offset amount increases.

In FIG. 7, when the copy button is pressed, the controller determines the number of copies, and if the number of copies is larger than a predetermined value, the rotation amount (movement amount) of the oil leveling roller 70 is increased to increase the cleaning force. Can be increased.

On the contrary, when the number of sheets is smaller than the predetermined value, the amount of rotation of the oil leveling roller 70 is small and efficient.

Further, similarly to the first embodiment, the number of feeding intervals of the oil leveling roller 70 and the pressure applied to the fixing roller 51 are controlled according to the number of copies to change the contact surface pressure with the fixing roller. However, the same effect can be obtained.

Further effects can be obtained by combining the first embodiment, the second embodiment and the third embodiment.

[0082]

As described above, according to the first aspect of the present invention, there is provided a roller pair of a fixing roller and a pressure roller which are rotatably arranged while being in pressure contact with each other. In an image forming apparatus having a fixing device for nip-conveying a recording material having an unfixed image at a pressure contact portion to be formed to heat and fix the unfixed image on the recording material, an environmental temperature detecting means for detecting an environmental temperature Alternatively, the recording material thickness detecting means for detecting the thickness of the recording material is provided, and the releasing agent supplying means for supplying the releasing agent onto the surface of the fixing roller and the releasing agent supplied in contact with the fixing roller are uniform. Release agent uniformizing means,
Release agent amount control means for contacting the fixing roller and controlling the amount of the release agent are sequentially arranged from the upstream side in the rotation direction of the fixing roller, and the release agent uniformizing means sets a contact surface with the fixing roller. A releasing agent uniformizing means capable of moving the fixing roller in a forward direction or a reverse direction with respect to the rotation direction of the fixing roller and changing the moving amount depending on the environmental temperature or the thickness of the recording material. By providing the image forming apparatus, the cleaning property of the offset toner can be improved, the life of the fixing roller can be extended, and the life of the releasing agent uniformizing means can be extended.

Further, according to the second aspect of the present invention, the releasing agent uniformizing means moves the contact surface with the fixing roller in the forward or reverse direction with respect to the rotation direction of the fixing roller. By providing an image forming apparatus characterized by being a release agent uniformizing means capable of changing the contact surface pressure depending on the environmental temperature or the thickness of the recording material, the cleaning property of the offset toner can be improved. The life of the fixing roller can be improved, and the life of the releasing agent can be extended.

According to a third aspect of the present invention, there is provided an image forming apparatus characterized in that the releasing agent homogenizing means has a heat-resistant felt or a heat-resistant non-woven fabric on the contact surface with the fixing roller. As a result, the cleaning property of the offset toner can be improved, the life of the fixing roller can be extended, and the life of the release agent uniformizing means can be extended.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a fixing device according to a first embodiment of the present invention.

FIG. 2 is a flowchart of the first embodiment of the present invention.

FIG. 3 is a control diagram of the first embodiment of the present invention.

FIG. 4 is a control diagram of the first embodiment of the present invention.

FIG. 5 is a flowchart of the second embodiment of the present invention.

FIG. 6 is a schematic diagram of a paper thickness detector according to a second embodiment of the present invention.

FIG. 7 is a flowchart of the third embodiment of the present invention.

FIG. 8 is a schematic sectional view of a conventional image forming apparatus.

FIG. 9 is a schematic sectional view of a conventional image forming apparatus.

FIG. 10 is a schematic sectional view of a conventional fixing device.

[Explanation of symbols] Pa, Pb, Pc, Pd image forming station 1a, 1b, 1c, 1d Photosensitive drum 12a, 12b, 12c, 12d charger 2a, 2b, 2c, 2d developing device 3 transfer part 31 transfer belt 3a, 3b, 3c, 3d Transfer charger 4a, 4b, 4c, 4d cleaner 5 Fixing device 51 fixing roller 52 Pressure roller 53 Release agent coating device 53a oil tank 53b Supply pipe 53c Pressing pad 53d regulation blade 54, 55 roller cleaning device 54a, 55a cleaning web 54b, 55b pressing roller 54c, 55c unwinding roller 54d, 55d winding roller 56,57 heater 58,59 Thermistor 60 oil removal blade 61 Paper cassette 62 Conveyor belt 68 Lower separation claw 70 Oil leveling roller 71 Heat-resistant felt 72 Lower layer 80 Paper thickness detector (recording material thickness detection means) 81 Registration roller 81a Upper roller 81b Lower roller 81c spring member 82 clutch 83 Potentiometer 90 Temperature detector (environmental temperature detection means)

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H027 DA12 DA13 DA45 DC02 EC06                       ED25 EE00 EE03 EE05 EF01                 2H033 AA23 AA25 BA25 BA30 BA43                       BA44 BA45 BA46 BA51 BB01                       BB18 BB28 CA07 CA08 CA16                       CA26 CA28 CA30                 4F040 AA05 AB08 AB20 AC01 BA14                       CB02 CB21 CB33 DA07 DA12                       DA14 DA18 DA20                 4F042 AA03 BA01 BA03 BA08 BA19                       BA25 CB02 CC02 CC09 DD02                       DD07 DD09 DD18

Claims (3)

[Claims] 1. A roller pair of a fixing roller and a pressure roller which are rotatably arranged while being in pressure contact with each other, and a pressure contact portion formed by the roller pair conveys a recording material having an unfixed image under pressure. In an image forming apparatus having a fixing device for heating and fixing an unfixed image on the recording material, an environmental temperature detecting means for detecting an environmental temperature, or a recording material thickness detecting means for detecting a thickness of the recording material, A releasing agent supplying means for supplying a releasing agent onto the surface of the fixing roller, a releasing agent uniformizing means for contacting the fixing roller and uniformizing the supplied releasing agent, and a releasing agent contacting and releasing the fixing roller. A releasing agent amount controlling means for controlling the amount of the releasing agent is sequentially arranged from the upstream side in the rotation direction of the fixing roller, and the releasing agent uniformizing means has a contact surface with the fixing roller in the rotating direction of the fixing roller. To move in the forward or reverse direction. And the amount of movement can be adjusted to the ambient temperature,
Alternatively, the image forming apparatus is a release agent uniformizing means that can be changed according to the thickness of the recording material. 2. A roller pair of a fixing roller and a pressure roller which are rotatably arranged while being in pressure contact with each other, and a pressure contact portion formed by the roller pair conveys a recording material having an unfixed image under pressure. In an image forming apparatus having a fixing device for heating and fixing an unfixed image on the recording material, an environmental temperature detecting means for detecting an environmental temperature, or a recording material thickness detecting means for detecting a thickness of the recording material, A releasing agent supplying means for supplying a releasing agent onto the surface of the fixing roller, a releasing agent uniformizing means for contacting the fixing roller and homogenizing the supplied releasing agent, and a releasing agent for contacting and releasing the fixing roller. A releasing agent amount control means for controlling the amount of the releasing agent is sequentially arranged from the upstream side in the rotational direction of the fixing roller, and the releasing agent uniformizing means has a contact surface with the fixing roller in the rotational direction of the fixing roller. To move in the forward or reverse direction The contact surface pressure can be adjusted to the ambient temperature,
Alternatively, the image forming apparatus is a release agent uniformizing means that can be changed according to the thickness of the recording material. 3. The image forming apparatus according to claim 1, wherein the releasing agent uniformizing means has a contact surface with the fixing roller made of a heat-resistant felt or a heat-resistant nonwoven fabric.