JP2002156860A - Fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of preventing toner adhering to a heating roller from being transferred to paper and also rapidly changing the set temperature of the heating roller when paper passing in the fixing device is faultily carried (jammed). SOLUTION: This image forming device is constituted of a heating roller 82 heated by a heating source 81, and a pressure roller 83 in press contact with the roller 82. In the device, a cleaning roller 84 for cleaning the roller 82 while coming into contact with the surface of the roller 82 is provided to be freely nearer to/away from the roller 82. In the case of providing 1st set temperature T1 and 2nd set temperature T2 different from the temperature T1 and changing the set temperature of the surface of the roller 82 to be low, the roller 84 is made to abut on the roller 82 and rotated together therewith.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a printer and a facsimile, and more particularly, to a heating roller for heating and fixing a transfer material carrying a toner image, and a heating device for a fixing belt. The present invention relates to a fixing device having a cleaning roller for cleaning a rotating body, and an image forming apparatus including the fixing device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a printer, and a facsimile, a heat roller method is often used as a fixing device for performing heat fixing processing of a recording material carrying a toner made of a heat-meltable resin or the like. Has been adopted.

[0003] A heat roller type fixing device has a release layer on a heat conductive substrate provided with a heat source such as a halogen heater.
Alternatively, a heat roller is formed by covering a heat conductive substrate with a heat-resistant elastic layer and further covering a release layer thereon, and a pressure roller having elasticity to press against the heat roller. By passing a recording material such as paper through a certain fixing nip portion, the toner image carried on the recording material is heated and fixed.

JP-A-6-332330, JP-A-7-3
Japanese Patent Application Publication No. 06609 proposes a fixing device in which a pressure roller is pressed against a heating roller to rotate so as to lower the set temperature of the fixing heating roller.

However, in an image forming apparatus having a fixing device without an automatic pressure roller release mechanism, the pressure roller is always in contact with the heating roller during image formation and during standby, so that the pressure roller is always somewhat high. The temperature was maintained, and even if the pressure roller was pressed against the heat roller, the temperature of the heat roller required a certain amount of time to decrease, and the user had to wait a long time to change the set temperature of the heat roller. . The waiting time can be shortened as the heat capacity of the pressure roller is set to be larger than the heat capacity of the heating roller. However, in this case, there is a problem that a decrease in the temperature of the heating roller surface becomes large at the time of normal image formation or the like. .

Further, when a heat source is provided on both the heating roller side and the pressing roller side, and the set temperature difference between the rollers is small,
Even if the set temperature of the pressure roller is lower than the set temperature of the heating roller, the effect of lowering the temperature due to the pressure rotation of the pressure roller is small.

In an image forming apparatus having a heat roller fixing device, a cleaning roller as described in Japanese Utility Model Application Laid-Open No. 28868/1994 is used as a means for cleaning the surface of the heat roller and preventing image contamination. Methods are known. In this case, Japanese Patent Application Laid-Open No. H11-242401
It is known that, as in the fixing device disclosed in Japanese Patent Application Laid-Open Publication No. H10-157, when the surface hardness of the cleaning roller is lower than the surface hardness of the heating roller, the adhesion of the cleaning roller to the heating roller is increased, and the cleaning property is improved.

In the fixing device disclosed in Japanese Patent Application Laid-Open No. H11-242401, the surface hardness of the cleaning roller is made lower than the surface hardness of the fixing roller, and the surface of the fixing roller is rubbed while the rotation of the cleaning roller is stopped. Is what you do.

However, Japanese Patent Application Laid-Open No. 11-242401 discloses
The fixing device disclosed in Japanese Patent Application Laid-Open Publication No. H11-157572 is a means necessary for increasing the cleaning efficiency by increasing the nip width between the heating roller and the cleaning roller. The lower the hardness of both the heating roller and the cleaning roller, the better. become. Whether or not the toner moves to the cleaning roller side in the fixing nip is determined by the surface property, and when compared under the same nip width condition, the condition regarding the surface property of the heating roller and the cleaning roller must be determined. However, more efficient cleaning properties cannot be obtained.

[0010]

SUMMARY OF THE INVENTION The present inventors have found that when switching from a high fixing set temperature to a lower set temperature, the heating roller and the pressure roller are not contacted for an unnecessarily long time without rotating. Further, the present inventors have studied a fixing device capable of reducing the waiting time at the time of temperature switching, and have completed the present invention.

That is, the cleaning roller is brought into contact with the heating roller only when the transfer material passing through the fixing device causes a conveyance failure (jam) to prevent the toner attached to the transfer material from transferring to the heating roller. In addition, the present invention provides a fixing device capable of changing the temperature of the surface of the heating roller to low by utilizing the contact of the cleaning roller when the setting temperature of the heating roller needs to be switched.

Further, there is provided a fixing device capable of shortening the waiting time at the time of changing the set temperature of the heating roller surface from a high-temperature mode for fixing thick paper to a plain paper mode for fixing plain paper when the temperature is changed. I do.

Further, there is provided a fixing device capable of shortening the waiting time at the time of changing the set temperature of the surface of the heating roller from a color mode for forming a color image to a monochrome mode for forming a black and white image. I do.

An object of the present invention is to provide a fixing device and an image forming apparatus which solve the above-mentioned conventional problems.

[0015]

The above object is achieved by the following constitution.

(1) In a fixing device comprising a heating rotator heated by a heating source and a pressing rotator pressed against the heating rotator, a cleaning roller for cleaning by contacting the surface of the heating rotator is provided. The heating rotator is provided so as to be able to approach and separate from the heating rotator, and the heating rotator has a first set temperature and a second set temperature different from the first set temperature, and a set temperature of the heating rotator surface The fixing roller is brought into contact with the heating rotator and rotated together when the fixing roller is changed to a lower fixing roller.

(2) In a fixing device comprising a heating rotator heated by a heating source and a pressing rotator pressed against the heating rotator, a cleaning roller for cleaning by contacting the surface of the heating rotator is provided. The fixing device is provided so as to be capable of coming in contact with and separating from the heating rotator, and the cleaning roller is brought into contact with the heating rotator for a predetermined time immediately after image formation, and is rotated together.

(3) In a fixing device comprising a heating rotator heated by a heating source, and a cleaning roller which comes into contact with the heating rotator so as to be able to come and go, and rotates together therewith.
When the cleaning roller rotates while being in contact with the heating rotator, the contact distance of the cleaning roller on the outer peripheral surface of the heating rotator is set to an integral multiple of the outer peripheral length of the heating rotator. Fixing device.

(4) A fixing device comprising a heating rotator having a multilayer structure having at least one elastic layer and a surface layer heated by a heating source, and a cleaning roller rotating together with the heating rotator. , Wherein the hardness of the surface layer of the cleaning roller is set lower than the hardness of the surface layer of the heating rotator.

(5) A fixing device comprising a heating rotator having at least one elastic layer heated by a heating source and a cleaning roller rotating together with the heating rotator in contact with the heating rotator. A fixing device wherein the micro hardness of the surface is set lower than the micro hardness of the surface of the heating rotator.

(6) An image forming apparatus comprising: the fixing device according to any one of (1) to (5); an image forming unit; and a sheet conveying unit.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a fixing device and an image forming apparatus according to the present invention will be described below with reference to the drawings.

(Embodiment of Image Forming Apparatus) FIG. 1 is a sectional configuration view of a color image forming apparatus showing an embodiment of an image forming apparatus provided with a fixing device according to the present invention.

This color image forming apparatus is called a tandem type color image forming apparatus, and a plurality of sets of image forming units 10Y, 10M, 10C, 10K arranged in tandem.
And a semiconductive endless belt-shaped intermediate transfer member 7 wound around a plurality of rollers and rotatably supported, a sheet feeding and conveying means, and a fixing device 8.

Image forming section 1 for forming a yellow image
0Y includes a charging unit 2Y, an exposing unit 3Y, a developing unit 4Y, a primary transfer unit 5Y, and a cleaning unit 6Y arranged around the image carrier (photoconductor) 1Y. The image forming unit 10M that forms a magenta image includes an image carrier (photoconductor) 1M, a charging unit 2M, an exposure unit 3M, and a developing unit 4.
M, a primary transfer unit 5M, and a cleaning unit 6M. An image forming unit 10C for forming a cyan image includes an image carrier (photoconductor) 1C, a charging unit 2C, an exposure unit 3C,
Developing unit 4C, primary transfer unit 5C, cleaning unit 6
C. The image forming unit 10K for forming a black image includes:
Image carrier (photoconductor) 1K, charging unit 2K, exposure unit 3
K, a developing unit 4K, a primary transfer unit 5K, and a cleaning unit 6K.

Image forming units 10Y, 10M, 10C, 10
The image of each color formed from K is transferred to primary transfer units 5Y and 5Y.
By M, 5C, and 5K, a color image is sequentially transferred onto the rotating intermediate transfer body 7 and synthesized. The transfer material (hereinafter, referred to as paper) P stored in the paper feed cassette 20 is fed by a paper feeding unit 21 and passes through a plurality of intermediate rollers 22A, 22B, 22C, 22D, a registration roller 23, and then to a secondary image. The color image is conveyed to the transfer means 5A and is collectively transferred onto the paper P. The paper P to which the color image has been transferred is subjected to a fixing process by the fixing device 8, and is held by a paper discharge roller 24 and placed on a paper discharge tray 25 outside the apparatus.

At the time of double-sided image formation, the sheet P on which an image is formed on the first side and discharged from the fixing device 8
From the paper discharge path, and the lower reverse paper path 27
After passing through A, 27B and 27C, they merge at the intermediate roller 22D. The sheet P that has been reversely conveyed is conveyed to the secondary transfer unit 5A via the registration roller 23, and the color image is collectively transferred onto the second surface of the sheet P. The paper P to which the color image has been transferred is subjected to fixing processing by the fixing device 8,
The sheet is nipped by a sheet discharge roller 24 and placed on a sheet discharge tray 25 outside the apparatus.

On the other hand, after the color image is transferred onto the paper P by the secondary transfer means 5A, the residual toner is removed by the cleaning means 6A from the intermediate transfer body 7 from which the paper P is separated by curvature.

During the image forming process, the primary transfer means 5K is always in pressure contact with the photosensitive member 1K. Other primary transfer means 5
Y, 5M, and 5C are in pressure contact with the corresponding photoconductors 1Y, 1M, and 1C only during color image formation. The secondary transfer unit 5A comes into pressure contact with the intermediate transfer body 7 only when the sheet P passes through the secondary transfer unit and secondary transfer is performed.

(Overall Configuration of Fixing Device) FIG. 2 is a sectional view showing an embodiment of the fixing device of the present invention.

The fixing device (roller fixing device) 8 includes a heating source 81, a heating roller (heating rotating body) 82, a pressure roller (pressure rotating body) 83, and the like. Around the heating roller 82, a cleaning roller 84, an oil application roller 85,
A cleaning roller 86, a non-contact type abnormal temperature preventing thermostat TS1, and a non-contact type temperature sensor TS2 are arranged.

As the heating source 81, a halogen lamp, induction heating means or the like is used. The heating roller 82 includes a heat conductive base (core metal) 821, a heat resistant elastic layer (hereinafter referred to as an elastic layer) 822 covering the outside of the heat conductive base 821, and a release layer 823 covering the outside of the heat conductive base 821. It is configured.

The pressure roller 83 is made of a heat conductive base (core metal).
An elastic layer 832 of silicone rubber or the like around 831;
Further, it comprises a release layer 833 whose outer layer is coated with a fluororesin. N is a pressure roller 83 and a heating roller 82
Is a fixing nip portion to be pressed against.

The temperature sensor TS2 detects the surface temperature of the heating roller 82. A control unit (not shown) controls the surface temperature of the heating roller 82 to a predetermined temperature based on the detection signal of the temperature sensor TS2.

When the sheet P is introduced into the fixing nip N where the heating roller 82 and the pressure roller 83 are pressed against each other, the heating source 8
The heat of the heating roller 82 heated by 1 is applied to the paper P, and the toner image t on the paper P is heated and fixed.

(Heating Roller) The heating roller 82 is a cylindrical body having a diameter of 20 to 70 mm including a heat conductive substrate 821, an elastic layer 822, and a release layer 823. As the cylindrical heat conductive substrate 821, an aluminum material having good heat conductivity (A5056, A5052, A5083, A6063, etc.) is mainly used, and a nonmagnetic stainless steel material (ST
KM11). The heat conductive substrate 821 is
Has the required mechanical strength and thickness (wall thickness) of 0.8 to 16
It is a cylindrical body having a thickness of mm.

The elastic layer 822 is made of, for example, silicone rubber or
It is formed of synthetic rubber such as fluorine rubber. Further image formation
In order to respond to high speed, filler and filler in the synthetic rubber
Oxidation of metals such as silica, alumina and magnesium oxide
5 to 30% by mass of the powder of the product to improve the thermal conductivity
Is preferred, and the thermal conductivity is (2-20) × 10 ^-3
Used as an elastic layer of about J / cm · s · K
I have. Use conductive carbon black as filler
For example, the electric resistance (volume resistivity) of the elastic layer 822 can be easily reduced.
It is effective to prevent the heating roller 82 from being charged. Bullet
The thickness (wall thickness) of the conductive layer 822 is preferably 0.5 to 5 mm.
Or 1 to 3 mm thick.

On the outer side (outer peripheral surface) of the elastic layer 822, a P-layer having a thickness of 15 to 70 μm is formed in order to improve the releasability from the toner.
A release layer 823 is provided by coating an FA (fluororesin) tube or applying a coating of a fluororesin (PFA, PTFE, or a mixture of PFA and PTFE) of 15 to 70 μm. The release layer 823 improves the releasability from the toner and enhances the durability of the elastic layer 822.
A fluorine rubber layer or a fluorine latex rubber layer may be provided outside the elastic layer 822, and a high release silicone rubber layer may be further provided thereon.

FIG. 3 is a layer configuration diagram showing another embodiment of the heating roller 82. In addition, about the code | symbol used in FIG. 3, the part which has the same function as FIG. 2 is attached | subjected. Further, points different from FIG. 2 will be described.

The heating roller 82 has a four-layer structure in which a heat conductive substrate 821 is covered with an elastic layer 822, a mixed layer 824 made of rubber and resin is further formed thereon, and a resin layer 825 is further formed thereon. It is.

The heat conductive substrate 821 and the elastic layer 822 have the same configuration as described above. The outermost resin layer 825 is formed of, for example, a fluororesin such as PFA and has a thickness of several tens.
It is a thin layer of μm. The resin layer 825 is formed of the release layer 823.
Similarly to the above, the releasability from the toner is improved, and the durability of the elastic layer 822 is enhanced.

The mixed layer 824 below the resin layer 825 is formed by mixing fluoro rubber and fluoro resin, and is a thin layer having a thickness of several tens μm. The mixed layer 824 is formed as an adhesive layer between the elastic layer 822 and the resin layer 825, and acts as a buffer between the resin layer 825 and the elastic layer 822 when the heating roller 82 rotates while being pressed against the pressing roller 83. Thus, the occurrence of cracks in the resin layer 825 is prevented.

(Pressing Roller (See FIG. 2)) A pressing roller 83 serving as a lower cylindrical fixing member paired with the upper heating roller 82 includes a heat conductive base 831, an elastic layer 832,
It comprises a release layer 833. The components of the pressure roller 83 include:
The material, characteristics, and dimensions are substantially the same as those of the components of the heating roller 82.

For example, a heat conductive substrate 831 using an aluminum material, and a sponge-like thickness using, for example, a silicone rubber layer or a fluorine rubber layer or a silicone rubber foam material on the outer peripheral surface of the heat conductive substrate 831. (Thickness) 0.5 ~
A soft roller having an outer diameter of about 20 to 70 mm formed by an elastic layer 832 made of a rubber layer having a thickness of 5 mm and a rubber hardness of 0 to 40 Hs (JIS, A rubber hardness). On the outer side (outer peripheral surface) of the elastic layer 832, a release layer 833 coated with a heat-resistant fluororesin such as PFA or PTFE having release properties is formed. A fixing nip portion N is formed between the upper heating roller 82 rotatably supported at the fixed position and the lower pressing roller 83 which is biased by a spring and pressed against the heating roller 82 to form the toner image t. Fixing is performed.

As another embodiment of the pressure roller 83,
Similar to the layer configuration diagram of the heating roller 82 in FIG. 3, a heat conductive substrate 831 is covered with an elastic layer 832, a mixed layer made of rubber and resin is further laminated thereon, and a resin layer is further laminated thereon. A pressure roller 83 having a four-layer structure is formed.

(Another Embodiment of Fixing Device) FIG. 4 is a sectional view showing another embodiment of the fixing device.

The fixing device 9 includes a heating source 91 such as a halogen lamp, a rotatable heating roller 92, a pair of upper and lower pressure rollers 93 A and 93 B which rotate by pressing, and a heating roller 92 and an upper pressure roller. The heating fixing belt (heating rotator) 90 and the like, which are rotatable around each outer peripheral surface of 93A, are constituted.

The fixing device 9 rotates the heat fixing belt 90 heated by the heat roller 92, and conveys the paper P by nipping it between a pair of rotating pressure rollers 93A and 93B. The belt 90 heats and fixes the toner image t on the sheet P.

An oil application roller 95 for applying oil to the heat fixing belt 90 is provided above the heat fixing belt 90.
A cleaning roller 96 for cleaning the surface of the oil application roller 95 is provided.

The upper pressure roller 93A is formed of a low hardness foamed elastic member. The lower pressure roller 93B has a rubber surface layer coated with a fluororesin such as PFA. The heating roller 92 is a roller in which a fluororesin layer is formed on a heat conductive substrate such as an aluminum material, and has a heating source 91 inside. The heat fixing belt 90 is an endless belt, has the same configuration as the layer configuration of the heating roller 82 shown in FIGS. 2 and 3, and is elastically deformable. That is,
The heat fixing belt 90 has a three-layer structure in which an elastic layer such as silicone rubber and a release layer are coated on a nickel electroformed layer of a heat conductive base or a heat resistant resin layer such as polyimide, or a heat conductive base. 4 consisting of elastic layer, mixed layer and resin layer
It is a layer configuration.

A thermostat TS1 is disposed near the outer peripheral surface of the heating roller 92, and a temperature sensor TS2 is disposed near the outer peripheral surface of the lower pressure roller 93B.

Below the fixing belt 90, a guide plate 98 is provided.
Is arranged. The sheet P conveyed to the fixing device 9 by a conveying unit (not shown) includes a guide plate 98 and a fixing belt 9.
After passing through the inclined gap of 0, the upper pressure roller 93A and the lower pressure roller 93B are fed into the fixing nip N where the lower pressure roller 93B is pressed.

The toner image t formed on the sheet P is heated by a heating source 91 in a fixing nip N, heated and melted by a heating roller 92 rotated by a driving means (not shown), and heated and melted. The pressure roller 93 </ b> A and the lower pressure roller 93 </ b> B are pressed against each other and are fixed on the sheet P.

(Cleaning Roller) In the fixing device (roller fixing device) 8 shown in FIG. 2, when the cleaning roller 84 is separated from the surface of the heating roller 82, it is disposed at a position not present above the heating roller 82. If the cleaning roller 84 is provided above the heating roller 82 to release the pressure contact of the cleaning roller 84, even if the cleaning roller 84 is not in contact with the heating roller 82,
Cleaning roller 8 due to rising hot air of heating roller 82
4 occurs. Therefore, the cleaning roller 8
4 is disposed at a position avoiding the upper portion of the heating roller 82.

A fixing device (belt fixing device) 9 shown in FIG.
Also, the cleaning roller 94 is
Place it away from the top of the.

The cleaning roller 84 has a structure in which a thin heat-resistant resin layer 842 is formed on a relatively thick heat-conductive substrate 841 such as metal (see FIG. 2). The cleaning roller 94 is made of a relatively thick thermally conductive substrate 94 such as a metal.
1 has a thin heat-resistant resin layer 942 (FIG. 4).
reference).

By forming the cleaning rollers 84 and 94 from members having a relatively large heat capacity, the efficiency of temperature reduction can be improved. Further, the heating roller 82, the cleaning roller 84, and the heating / fixing belt 90 are controlled so that the temperature drop does not become unnecessarily large during the control after the jam processing.
It is better to keep the contact time between the cleaning roller 94 and the cleaning roller 94 to the minimum necessary for cleaning.

The hardness H 1 of the heat-resistant resin layer 842 on the surface of the cleaning roller 84 depends on the release layer 82 on the surface of the heating roller 82.
3 or lower than the hardness H2 of the resin layer 825. Similarly, the hardness H1 of the heat-resistant resin layer 942 on the surface of the cleaning roller 94 is set lower than the hardness H2 of the surface layer of the heat fixing belt 90.

Heating roller 82 and cleaning roller 84
By determining the surface microhardness condition or the hardness condition of the surface layer of the heating roller 82 and the cleaning roller 8,
4 shows that the cleaning roller 84
The cleaning performance can be improved by increasing the adhesion between the cleaning roller 84 and the toner. At this time, by setting the material such that the contact angle of the surface layer of the cleaning roller 84 is smaller than the contact angle of the surface layer of the heating roller 82, the cleaning performance of the adhered matter such as toner can be further improved. .

The fixing device of the present invention is also applicable to a system having a cleaning roller also serving as an oil application and a second cleaning roller in contact with the cleaning roller.

(Control of Cleaning Roller 84) FIG. 5 is a block diagram showing control of the cleaning roller.

The cleaning roller 84 is driven by a latch solenoid (not shown), and is always stopped and held at a position shown by a broken line.

When it is detected by the sensor that the paper P passing through the fixing device 8 has a conveyance failure, the control means 100 drives a latch solenoid (not shown) to urge the cleaning roller 84 by a spring (not shown). do it,
It is brought into contact with the surface of the heating roller 82. The cleaning roller 84 is pressed against the rotationally driven heating roller 82 and rotates together to clean the toner on the heating roller 82, and the attached matter such as the toner adhered to the heating roller 82 is transferred to the paper P. Prevent things. Accordingly, it is possible to prevent the toner offset to the heating roller 82 from contaminating the sheet P when the sheet P having the conveyance failure stagnated in the fixing nip portion N.

In the fixing device 9 as well, when it is detected by the sensor that the conveyance failure of the paper P has occurred, the cleaning roller 94 is driven by a latch solenoid and is urged by a spring (not shown), so that the surface of the heat fixing belt 90 is heated. To clean the toner on the heat fixing belt 90. This prevents the toner offset to the heating and fixing belt 90 from contaminating the sheet P when the sheet P in which the conveyance failure has occurred stays in the fixing nip portion N.

The control means 100 has a first set temperature T
1 and a second set temperature T2 different from the first set temperature T1 are preset, and when the set temperature of the surface of the heating roller 82 is changed to be low, the cleaning roller 84 is brought into contact with the heating roller 82. Are rotated together a predetermined number of times.

That is, the first set temperature T1 is the normal mode for fixing plain paper, the second set temperature T2 is the high temperature mode for fixing thick paper, and the first set temperature T2 is changed from the second set temperature T2 to the first set temperature T2.
When the set temperature of the surface of the heating roller 82 is changed to 1, the cleaning roller 84 is brought into contact with the heating roller 82 and is rotated together to lower the surface temperature of the heating roller 82.

For example, 50 to 90 usually used frequently are used.
g / m ² for the plain paper mode corresponding to the paper P
150-170 ° C. is selected as the set temperature T1, and 170-190 ° C. as the second set temperature T2 for the cardboard mode corresponding to 100-200 g / m ² of paper P such as a postcard.
Select

In a color image forming apparatus capable of setting a monochrome mode and a color mode, the first set temperature T
Reference numeral 1 denotes a monochrome mode for monochrome image formation, and the second set temperature T2 is a color mode for color image formation. When the set temperature of the surface of the heating roller 82 is changed from the second set temperature T2 to the first set temperature T1 at a low level, the cleaning roller 84 is brought into contact with the heating roller 82, and is rotated together with the surface temperature of the heating roller 82. Lower.

For example, the first black-and-white image forming mode can be set according to the type of toner used for forming a black-and-white image.
150-170 ° C. is selected as the set temperature T1, and 170-190 ° C. is set as the second set temperature T2 for the color mode.
Select ° C.

That is, the first set temperature T1 is a normal mode for fixing a binary image, the second set temperature T2 is a high temperature mode for fixing a multi-valued (three or more) image, and the second set temperature T2 is set.
When the set temperature of the surface of the heating roller 82 is changed to the first set temperature T1, the cleaning roller 84 is brought into contact with the heating roller 82 and rotated together to lower the surface temperature of the heating roller 82.

For example, if the first set temperature T1 is 150 to
170 ° C. is selected, and 170 to 1 is set as the second set temperature T2.
Select 90 ° C.

The cleaning roller 84 is a heating roller 82
When the cleaning roller 84 rotates in contact with the heating roller 82, the contact distance of the cleaning roller 84 on the outer peripheral surface of the heating roller 82
Is an integral multiple of the outer peripheral length of. The cleaning roller 84 is brought into contact with the heating roller 82 while rotating so that the surface temperature of the heating roller 82 does not become uneven, and the contact distance is set to an integral multiple of the outer peripheral length of the heating roller 82. Is desirable.

Further, immediately after the sheet P has passed the detecting section of the sheet discharge sensor S after the image formation is completed, the cleaning roller 8
By bringing the heating roller 4 into contact with the heating roller 82 and rotating it together for a predetermined time, it is possible to suppress a temperature overshoot of the heating roller 82 after the image formation is completed.

(Example of Fixing Device) [Example 1] Heating roller 82: aluminum core + silicone rubber + surface P
FA resin layer, halogen heater installed inside cylindrical aluminum core, Pressure roller 83: Aluminum core + silicone rubber + surface P
FA resin layer, halogen heater installed inside cylindrical aluminum core, cleaning roller 84: aluminum core + surface fluoro rubber layer, temperature detecting means: non-contact type abnormal temperature prevention for heating roller 82 and pressure roller 83 Thermostats TS1 and TS
3. Non-contact type temperature sensors TS2 and TS4 are arranged and the energization to the halogen heater is controlled by the detection output. Automatic pressure release mechanism: Automatic pressing of pressure roller 83 and cleaning roller 84 to heating roller 82 There is a release mechanism. Heating roller set temperature: Set temperature 1 to 180 ° C (Normal process mode) Set temperature 2 to 140 ° C (Low speed process mode) Pressure roller set temperature: Set temperature 1 to 140 ° C (Normal process mode) Setting Temperature: 2 to 140 ° C. (low-speed process mode) The heating roller 82 is driven to rotate, the pressure roller 83 and the cleaning roller 84 are driven or driven to rotate, and control in each mode is as follows.

During normal image formation, the pressure roller 83
Only the heating roller 82 is pressed and rotated.

Immediately after the jam processing, only the cleaning roller 84 is pressed against the heating roller 82 and rotated. The contact distance between the heating roller 82 and the cleaning roller 84 is twice as long as the outer peripheral length of the heating roller 82 (the amount required when the maximum amount of toner adhering on the transfer paper P is completely transferred to the heating roller 82). Release the crimping at the place. When the heating roller 82 has risen to the set temperature again, the operation proceeds to the image forming operation.

When the set temperature is changed (in a decreasing direction),
Both the cleaning roller 84 and the pressure roller 83 are pressed against the heating roller 82 and rotated. When both the heating roller 82 and the pressure roller 83 reach the set temperature, both rollers 82, 8
After releasing the pressure contact of No. 3, the operation proceeds to the image forming operation.

When the set temperature is changed (in a rising direction),
Neither the cleaning roller 84 nor the pressure roller 83 is pressed against the heating roller 82. Heating roller 82, pressure roller 8
When the temperature reaches the set temperature, the operation proceeds to the image forming operation.

[Example 2] Heating roller 82: Aluminum core metal + silicone rubber + surface P
FA resin layer, halogen heater installed inside cylindrical aluminum core, pressure roller 83: aluminum core + silicone rubber + surface P
FA resin layer, halogen heater installed inside cylindrical aluminum core, cleaning roller 84: aluminum core + surface fluoro rubber layer, surface of cleaning roller 84 has a hardness (for example, Shore D hardness) relative to the surface PFA resin layer. ) Is a soft fluorine rubber elastic layer. Temperature detecting means: Thermistor temperature sensor is brought into contact with the surface of both the heating roller 82 and the pressing roller 83, and the detection output controls the energization to the halogen heater. Heating roller 82: Aluminum core + silicone rubber 2 mm thick (hardness Asker-C30 °) + surface PFA resin layer, halogen heater installed inside cylindrical aluminum core, pressure roller 83: aluminum core + silicone rubber + surface P
FA resin layer, halogen heater installed inside cylindrical aluminum core, cleaning roller 84: aluminum core + 2 mm thick silicone rubber (hardness Asker-C30 °) + surface fluorine rubber layer.

Temperature detecting means: Non-contact type thermostats TS1 and TS3 for preventing abnormal temperature, non-contact type temperature sensors TS2 and TS4
The energization of the halogen heater is controlled by the detection output. Surface hardness: The surface micro hardness of the cleaning roller 84 is softer than the surface micro hardness of the heating roller 82.

(Other Embodiments of Image Forming Apparatus) The color image forming apparatus of the present invention is not limited to the tandem type color image forming apparatus shown in FIG. 1, but is formed on a plurality of image carriers. The present invention is also applicable to a color image forming apparatus of a system in which a toner image t is directly transferred to a sheet P to form a superimposed toner image t, and the superimposed toner image t is fixed by a fixing device.

In the color image forming apparatus of the present invention, the color images are formed by superimposing the respective color toner images t sequentially formed on the image carrier and then transferring the color toner images t onto the sheet P once at the transfer section. Thereafter, the paper P is peeled off from the surface of the image carrier, and the present invention is also applicable to a color image forming apparatus of a system in which a superposed toner image t is fixed by a fixing device. The present invention is also applicable to a monochrome image forming apparatus.

[0083]

According to the present invention, the cleaning roller is brought into contact with the surface of the heating rotator only when the paper passing through the fixing device causes a conveyance failure (jam), so that the toner adhering to the heating roller is removed. The temperature of the surface of the heating rotator can be quickly changed to a low level while preventing the transition to the heat transfer.

When the set temperature of the surface of the heating roller is changed from the high-temperature mode for fixing thick paper to the plain paper mode for fixing plain paper, the waiting time for switching the temperature can be reduced. .

Further, there is provided a fixing device capable of shortening the waiting time at the time of switching the temperature when the set temperature of the surface of the heating roller is changed from the monochrome mode for monochrome image formation to the color mode for color image formation. Is done.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of an image forming apparatus including a fixing device according to the present invention.

FIG. 2 is a sectional view showing an embodiment of the fixing device of the present invention.

FIG. 3 is a layer configuration diagram showing another embodiment of the heating roller.

FIG. 4 is a sectional view showing another embodiment of the fixing device.

FIG. 5 is a block diagram illustrating control of a cleaning roller.

[Explanation of symbols]

 Reference Signs List 8 fixing device (roller fixing device) 9 fixing device (belt fixing device) 10Y, 10M, 10C, 10K image forming section 81, 91 heating source 82 heating roller (heating rotator) 83 pressure roller (pressure rotator) 84 , 86, 94, 96 Cleaning roller 85, 95 Oil application roller 90 Heat fixing belt (heating rotator) 92 Heat roller 93A Upper pressure roller 93B Lower pressure roller 100 Control means 821, 831 Thermal conductive substrate (core metal) 822, 832 Elastic layer 823, 833 Release layer 824 Mixed layer 825 Resin layer 842, 942 Heat-resistant resin layer 841, 941 Thermal conductive substrate N Fixing nip P Transfer material (paper) T1 First set temperature T2 Second set temperature TS1, TS3 Thermostat TS2, TS4 Temperature sensor t Toner image

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2H030 AD04 AD07 AD18 2H033 AA08 AA45 AA46 AA47 BA30 BA49 BA54 BA55 BA57 CA01 CA07 CA16 CA18 CA22 CA30

Claims (19)

[Claims] A heating rotator heated by a heating source;
A fixing device configured to contact the surface of the heating rotator for cleaning, the cleaning roller being provided so as to be capable of coming into contact with and separating from the heating rotator; Has a first set temperature and a second set temperature different from the first set temperature, and when the set temperature on the surface of the heating rotator is changed to be lower, the cleaning roller is applied to the heating rotator. A fixing device that is brought into contact with and rotated together. 2. A heating rotator heated by a heating source,
In a fixing device including a pressing rotator that is in pressure contact with the heating rotator, a cleaning roller that contacts and cleans the surface of the heating rotator is provided so as to be able to contact and separate from the heating rotator, and the cleaning roller , Immediately after image formation,
A fixing device, wherein the fixing device is brought into contact with the heating rotator for a predetermined time and is rotated together. 3. The fixing device according to claim 1, wherein the cleaning roller contacts the heating rotator when a transfer material passing through the inside of the fixing device has a conveyance failure. 4. The first set temperature is a normal mode for fixing plain paper, the second set temperature is a high temperature mode for fixing thick paper, and the heating is performed from the second set temperature to the first set temperature. When lowering the set temperature of the rotating body surface,
Bringing the cleaning roller into contact with the heating rotator,
The fixing device according to claim 1, wherein the fixing device is rotated together. 5. The method according to claim 1, wherein the first set temperature is a color mode for forming a color image, the second set temperature is a black and white mode for forming a black and white image, and the second set temperature is the second mode from the first set temperature.
2. The cleaning roller according to claim 1, wherein when the set temperature of the surface of the heating rotator is reduced to a set temperature, the cleaning roller is brought into contact with the heating rotator and rotated together.
Or the fixing device according to item 3. 6. The heating method according to claim 1, wherein the first set temperature is a mode for a binary image, the second set temperature is a mode for a multi-valued image, and the heating rotation is performed from the second set temperature to the first set temperature. 4. The fixing device according to claim 1, wherein when the set temperature of the body surface is changed to be lower, the cleaning roller is brought into contact with the heating rotator and is rotated together. 5. 7. The mode wherein the first set temperature is a mode at a first process speed, the second set temperature is a mode at a second process speed, and the first process speed is lower than the second process speed. When the set temperature of the surface of the heating rotator is changed from the second set temperature to the first set temperature, the cleaning roller is brought into contact with the heating rotator and rotated together. The fixing device according to claim 1. 8. The apparatus according to claim 1, wherein the cleaning roller is arranged at a position avoiding an upper portion of the heating rotator when the cleaning roller is separated from the surface of the heating rotator. The fixing device as described in the above. 9. The heating rotator has a configuration in which an elastic layer is coated on a heat conductive substrate and a release layer is further formed thereon, and the cleaning roller is made of metal or a thin heat-resistant resin on a heat conductive substrate. The fixing device according to claim 1, wherein the fixing device has a layer. 10. A fixing device comprising: a heating rotator heated by a heating source; and a cleaning roller which rotates in contact with the heating rotator so as to be able to come into contact with and separate from the heating rotator. The fixing device according to claim 1, wherein a contact distance of the cleaning roller on the outer peripheral surface of the heating rotator when the cleaning roller contacts and rotates is set to an integral multiple of an outer peripheral length of the heating rotator. 11. At least one heated by a heating source
A heating rotator having a multilayer structure having an elastic layer and a surface layer,
In a fixing device including a cleaning roller that rotates together with the heating rotator, a hardness of a surface layer of the cleaning roller is set to be lower than a hardness of a surface layer of the heating rotator. Fixing device. 12. At least one heated by a heating source
In a fixing device including a heating rotator having an elastic layer of a layer and a cleaning roller rotating together with the heating rotator, the micro hardness of the surface of the cleaning roller is determined by the micro hardness of the surface of the heating rotator. A fixing device characterized by being set to have a lower hardness. 13. The fixing device according to claim 11, wherein a contact angle of the surface layer of the cleaning roller with water is smaller than a contact angle of the surface layer of the heating rotator with water. 14. The cleaning roller according to claim 1, wherein said cleaning roller is a first cleaning roller which is not impregnated with a release agent, and which is in contact with a surface of an oil application roller which is impregnated with a release agent which rotates while being in contact with said heating rotator. 14. The fixing device according to claim 10, further comprising a second cleaning roller that is not impregnated with a release agent to be cleaned. 15. The fixing device according to claim 1, wherein the heating rotator is a heating roller having a roller shape. 16. A heating fixing belt according to claim 1, wherein said heating rotator is a heating fixing belt having an endless belt shape.
The fixing device according to any one of claims 15 to 15. 17. An image forming apparatus comprising: the fixing device according to claim 1; an image forming unit; and a sheet conveying unit. 18. The image forming apparatus according to claim 17, wherein said image forming means is capable of outputting images of at least two colors.
An image forming apparatus according to claim 1. 19. The image forming apparatus according to claim 17, wherein the image forming unit is capable of forming an image on both sides of the sheet conveyed by the sheet reversing and conveying unit.