JP2003280437A - Cleaning device for fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent image soiling due to back soiling offset after a jam processing. <P>SOLUTION: 1. The abutting pressure of a cleaning member is made great when copying again after the jam processing. 2. Abutting pressure is varied according to the fixing roller temperature at jam processing. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is formed on a heat roller type toner image fixing device, that is, a recording material, which is most commonly used in electrostatic recording devices such as electrophotographic copying machines and facsimiles. To remove and clean the toner adhering to the roller in a toner image fixing device provided with a fixing roller that heats and melts the toner in contact with the toner image, and a pressing roller that presses the recording material between the fixing roller and sends the recording material. The present invention relates to a fixing device cleaning device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine, there is widely used a web cleaning apparatus which cleans a residual toner on a member to be cleaned such as a fixing roller by a cleaning web made of non-woven fabric or the like. It is used.

FIG. 2 shows a toner image T formed by electrophotography.
1 shows an apparatus for fixing the paper on the plain paper P by heating.
In FIG. 2, reference numeral 1 denotes a fixing roller which is a fixing rotary member having a heater 3 for heating such as a halogen heater therein, and is rotated in the direction of an arrow by receiving a driving force from a drive motor (not shown).

A pressure roller 2 is supported below the fixing roller 1 by a bearing, and is arranged so as to be in pressure contact with the fixing roller 1 at least during fixing by a known pressure means. It is adapted to rotate with the rotation of the roller 1.

Further, a temperature sensitive element 4 such as a thermistor or a thermocouple is arranged in contact with the outer peripheral surface of the fixing roller 1, and a detection signal of the temperature sensitive element 4 is transmitted to a known control means, which controls the heater 3. The temperature of the outer peripheral surface of the fixing roller 1 is maintained at the toner image melting temperature by controlling the output or the applied voltage or the like.

Separation claws 51 and 52 for surely separating the fixed plain paper P from the rollers are in contact with the fixing roller 1 and the pressure roller 2, and the separation claws are made of a heat-resistant resin. It is formed by coating a fluororesin on a polyimide or polyamide resin.

On the other hand, a cleaning device 6 for removing foreign matters such as offset toner and paper dust adhered to the surface of the fixing roller 1 from the surface of the fixing roller 1 is disposed above the fixing roller 1. A cleaning web 60 made of a heat-resistant nonwoven fabric such as Nomex or Himeron is used.

The web pressing roller 65 is rotatably supported at its both ends by bearings 72, and presses against the fixing roller 1 to remove foreign matter such as offset toner and paper dust adhering to the surface of the fixing roller 1 from the roller surface. Prevents offset.

The web is wound up by a predetermined amount per copy by a driving means (not shown) in synchronism with the copy operation, regardless of copying one by one or copying a plurality of continuous sheets.

[0010]

However, in the above-mentioned conventional example, during the multi-rotation before the roller after the JAM treatment, the toner remaining between the cleaning web and the fixing roller slips through, and the fixing roller moves to the pressure roller. There is a possibility that backside smear offset occurs in which the transferred residual toner is retransferred to the back side of the copy paper.

The back smear offset is more remarkable after JAM processing than during normal copying for the following reasons.

During normal copying, the web is wound up in synchronism with the copying operation, and the unused surface is always supplied as the fixing roller rotates.

Further, a small amount of the passing-through toner which cannot be completely collected by the cleaning web is dispersed on the surfaces of both the fixing roller and the pressure roller and evenly flows out to both the front and back surfaces of the transfer material. It is hardly noticeable as an image stain.

On the other hand, after the JAM treatment, when the temperature is raised to a predetermined temperature and the pre-multi-rotation is started, the web is not wound up until the copying is started. The amount of residual toner that has slipped through becomes larger than that during normal copying.

When the passing toner on the fixing roller comes into contact with the pressure roller, the toner solidifies on the pressure roller having a low temperature.
Since the toner adheres, most of the slipped toner is transferred to the pressure roller side.

When the transfer material is fed here, most of the toner on the pressure roller is retransferred to the back side of the transfer material, which is inferior in releasability to the pressure roller, and back stain offset occurs.

When a JAM occurs, the heater is turned on.
Since FF occurs and the temperature of the fixing roller decreases, if JAM occurs during the passage of the transfer paper through the NIP portion of the fixing roller and the pressure roller, when the transfer paper is taken out during the JAM processing, the temperature before the passage of the NIP portion is exceeded. Since the unfixed toner on the transfer paper is not completely melted and fixed, a large amount of offset toner adheres to the fixing roller.

When a large amount of the offset toner slips through the web, the degree of back stain becomes large.

This phenomenon is more remarkable when the temperature of the fixing roller is further lowered due to a long time of standing after the JAM treatment.

It has been confirmed that offset toner can be reliably blocked by increasing the contact pressure of the web roller, which is effective in preventing back stain offset. However, the contact pressure of the web roller should always be increased. Due to
The fixing roller life may be shortened.

It is an object of the present invention to solve the above-mentioned problems and to provide a fixing device cleaning device capable of preventing back stain offset even after JAM processing without impairing the life of the fixing roller.

[0022]

According to the first invention of the present application, the above object is to provide a fixing rotating member which heats and fixes the toner by contacting the toner image formed on the transfer material, and the fixing device. In an apparatus provided with a cleaning member for removing and cleaning the toner adhering to the rotating body, by making the contact pressure of the cleaning member larger than that during normal copying until the first predetermined number of sheets after JAM processing is completed, This is achieved by setting so that the toner remaining between the fixing rotating member and the cleaning member is prevented from passing through.

According to the second invention of the present application,
A fixing rotary member that heats and fixes the toner by contacting the toner image formed on the transfer material, and a cleaning member for removing and cleaning the toner adhering to the fixing rotary member. Depending on the roller temperature,
By changing the contact pressure of the cleaning member until the copy of the first predetermined number of sheets after the JAM processing is completed,
This is achieved by setting so that the toner remaining between the fixing rotating member and the cleaning member is prevented from passing through.

(Operation) According to the first invention of the present application, cleaning is performed by increasing the contact pressure of the cleaning member higher than that during normal copying until the first predetermined number of sheets after JAM processing is completed. Since the toner remaining between the member and the fixing rotator is reliably collected, back stain offset due to slipping of the residual toner is prevented.

According to the second invention of the present application, JAM
By changing the contact pressure of the cleaning member until the end of the first predetermined number of copies after the JAM processing according to the temperature of the fixing rotary member during processing, the toner remaining between the cleaning member and the fixing rotary member is changed. Is reliably collected, so that backside smear offset due to slipping of residual toner is prevented.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) First, a first embodiment of the present invention will be described.

The structure of the fixing device of this embodiment will be described below with reference to FIG.

First, in the fixing roller 1, a heat-resistant elastic body layer 12 having a thickness of about 0.1 to 1 mm is formed on the outer peripheral surface of a metal hollow roller core 11 made of aluminum, stainless steel, iron or the like, and further thereon. The resin layer 13, which is a release layer, is 1.0 to
It is formed with a thickness of about 40 μm.

The pressure roller 2 has a relatively thick elastic layer 22 made of silicone rubber, fluororubber, fluorosilicone rubber or the like on the outer peripheral surface of a metal roller core 21 (for example, 5 to 10).
mm) and a fluororesin layer 23, which is a release layer, is further provided thereon with a thickness of about 30 to 50 μm.

The cleaning device 6 uses a cleaning web 60 made of a heat resistant nonwoven fabric such as Nomex or Himeron. This web 60 is usually made by mixing aromatic polyamide fibers with soft polyester fibers at high temperature to make a non-woven fabric with appropriate softness and strength, and adding silicone oil having a viscosity of about 10,000 cm stocks to the non-woven fabric. It is impregnated at high temperature and wound up.

The web pressing roller 65 is a metal cored bar covered with a heat-resistant rubber layer such as silicone rubber, and is made into a sponge state by adding a foaming agent to the rubber to obtain sufficient softness. . Rubber hardness is 10-2
0 ° (Asker-C) is used.

The above is the same structure as the conventional fixing device shown in FIG. 2, but the difference from the prior art of this embodiment is that the bearing 72 moves when the web contact pressure adjusting cam 67 rotates under the control of the sequence. However, the contact pressure of the web pressing roller 65 against the fixing roller 1 can be changed.

Hereinafter, the control method in this embodiment will be described with reference to FIG.
A description will be given based on (FIG. 3).

Normally, the contact pressure between the web and the fixing roller is 2
Although cleaning is performed with kg, when JAM occurs, the heater 3 is turned on again after the JAM treatment, and the temperature sensing element 4 changes the surface temperature of the fixing roller 1 to the front multi-rotation start temperature of the fixing roller 1 (main The sequence in which the cam 67 rotates such that the contact pressure per roller is 5 kg from the time when a temperature lower than 10 ° C. lower than 195 ° C. in the embodiment is detected until the end of the first copy. And

As a result, the fixing roller 1 can be used during JAM processing.
It is characterized in that the offset toner adhered to is prevented from slipping through due to multiple pre-rotation after JAM processing. The number of copies with a web contact pressure of 5 kg is JAM
The number of processed sheets is not limited to one, but may be an appropriate predetermined number that can prevent the offset toner from passing through.

The experimental results of this example and the conventional example will be described below. With each of these devices, 10 sheets of A4 size paper were printed at a predetermined chart at an ambient temperature of 15 ° C. at 50 sheets / minute.
By using a means such as opening the main body cover when copying 0 sheets continuously, forcibly generate JAM for the last 100 sheets,
After the AM treatment, the presence or absence of backside smear offset was confirmed when five sheets were continuously passed.

The results are shown in Table 1.

[0038]

[Table 1]

As shown in Table 1, in comparison with the conventional example, it was possible to prevent back stain offset after JAM processing in the example. On the contrary, temporarily increasing the contact pressure of the web tends to shorten the life of the fixing roller.
If it is less than kg, the fixing roller life is guaranteed 50
More than 10,000 sheets are secured, which is not a problem.

In this embodiment, the cleaning web is used as the cleaning member, but the cleaning member is not limited to the cleaning web, and may be a cleaning roller, a cleaning pad, or a cleaning blade.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

Also in this embodiment, the fixing device cleaning device is the same as that described in the embodiment shown in FIG. 1, but the web contact pressure adjusting cam 67 controlled by the control device 16 shown in FIG. 3 is used. Only the control method of is different.

The control device 16 shown in FIG. 3 controls the timing of the entire operation of the image forming apparatus.
The formation of a series of images such as formation of the upper toner image, transfer to the transfer material at the transfer separation portions 34 and 35, fusion fixing to the transfer material at the fixing device 15, and operation of the web contact pressure adjusting cam 67 are performed. It is controlled collectively.

The web contact pressure is usually 2 kg.
If the surface temperature of the fixing roller detected by the temperature sensitive element 4 is 160 ° C. or higher when returning after the M treatment, JA
The web contact pressure is 3k until the end of the first sheet after M treatment.
When the temperature is less than 160 ° C. g, the rotation angle of the cam 67 is controlled so that the web contact pressure is 5 kg.

Table 2 shows the experimental results obtained by the same method as in the first embodiment.

[0046]

[Table 2]

As shown in Table 2, compared to the conventional example, the second example was also able to prevent back stain after the JAM treatment.

That is, in this embodiment, when the time left after the occurrence of JAM is long, the temperature of the fixing roller during the JAM processing becomes low, and at that time, the unfixed image is passed between the fixing roller and the pressure roller. The amount of offset toner that adheres to the fixing roller when printed on paper will also increase.
By increasing the web contact pressure as compared with the case where the fixing roller temperature during the processing is high, it is possible to suppress the back stain after the JAM processing.

On the contrary, although the fixing roller life tends to be shortened by temporarily increasing the contact pressure of the web, if the contact pressure is 7 kg or less even when the fixing roller temperature drops to 160 ° C. or lower, The service life is guaranteed at 500,000 or more, which is not a problem.

As in the first embodiment, the cleaning member is not limited to the cleaning web but may be a cleaning roller, a cleaning pad, or a cleaning blade.

[0051]

As described above, according to the first invention of the present application, the contact pressure of the cleaning member is made higher than that during normal copying until the first predetermined number of copies after JAM processing is completed. By doing so, it is possible to prevent the residual toner from slipping through and reliably suppress the back stain offset.

According to the second invention of the present application,
By changing the contact pressure of the cleaning member until the end of copying the first predetermined number of sheets after JAM processing according to the temperature of the fixing roller during JAM processing, it is possible to prevent slipping of offset toner and to prevent back stain offset. Can be reliably suppressed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a fixing device according to an exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a schematic configuration of a conventional fixing device.

FIG. 3 is a cross-sectional view showing a schematic configuration of an image forming apparatus including a fixing device according to an exemplary embodiment of the present invention.

[Explanation of symbols]

16 Control device 60 web 61 Web winding shaft 65 Web pressure roller 66 Web feed axis 67 Web contact pressure adjustment cam

Claims (2)

[Claims] 1. A pair of fixing rotators for heating and fixing the toner in contact with a toner image formed on a transfer material, and a cleaning member for removing and cleaning the toner and the like adhering to the fixing rotator. In the device, until the first predetermined number of copies after JAM processing is completed,
A fixing device cleaning device in which the contact pressure of the cleaning member is made higher than during normal copying. 2. A pair of fixing rotators for heating and fixing the toner in contact with a toner image formed on a transfer material, and a cleaning member for removing and cleaning the toner and the like adhering to the fixing rotator. The apparatus according to claim 1, wherein the contact pressure of the cleaning member is changed according to the temperature of the fixing rotary member during JAM processing.
Fixing device cleaning device.