JPH05204274A - Cleaning device for fixing device - Google Patents

Abstract

PURPOSE:To take up a web only when the extent of the contamination of the web exceeds a fixed value by estimating the extent of the contamination of the web in a device where a heating roller is cleaned by a cleaning device. CONSTITUTION:A heating roller 2 provided with a heating source 3 and a pressuring roller 5 are arranged in a fixing device 1, and the cleaning device 10 using the web 11 is arranged for the roller 2, so that toner, etc., adhering to the surface of the roller is removed by the web 11. In the cleaning device 10, a take-up shaft 12 is driven by a driving motor 15, and the motor 15 is driven based on the estimated value of the contamination in a controller 20. The controller 20 estimates the contamination of the roller by using information such as the number of copies, the size of paper and the number of sheets to which fixing is performed at temperature at which the contamination exceeding a torelance occurs, and then operation for winding up the web is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a web driving means for cleaning a fixing roller in a heat roller type fixing device, and more particularly to a mechanism for winding a web by predicting the degree of dirt of the web. It relates to a device which can be activated and prevent the dirt of the web from being transferred to the next copy.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electronic copying machine or a laser printer for making a copy by using an electrophotographic system, an image carrier such as a photosensitive drum is
A mechanism for forming a toner image using dry toner is provided. The toner image formed on the photoconductor drum is transferred to a sheet by an image transfer unit, and the sheet carrying the toner image is fixed by a fixing device and is ejected as a copy. In general, a heat roller type fixing device is often used as the fixing device. In the heat roller type fixing device, a heating roller provided with a heating source such as a halogen lamp and a pressure roller are opposed to each other. The rollers are arranged so that a predetermined pressure is set between the rollers. Then, the sheet carrying the toner image is passed between both rollers to melt the toner by heat,
The melted toner is pressed against the paper to be fixed.

In the heat roller type fixing device constructed as described above, the toner image carried on the paper is
There is a problem that when the toner comes into direct contact with the heating roller and the toner is melted by the heat of the heating roller, a part of the toner remains attached to the surface of the roller and the toner is offset. When the heating roller becomes dirty, the toner adheres to other parts of the paper, and the copy becomes dirty. Therefore, in order to remove stains on the heating roller, a cleaning device using a web is arranged as disclosed in JP-A-59-30575.

In the above-mentioned cleaning device, a mechanism for cleaning the surface of the roller is constituted by using the means for driving the web intermittently, and for driving the web,
Information on the temperature of the fixing roller is used. With respect to the cleaning device, when the temperature of the fixing device reaches a certain temperature or higher, the drive mechanism for the web winding shaft operates to wind the web for a certain length.

[0005]

However, in the fixing device of the heat roller system, the toner offset occurs in addition to the fixing temperature, the density of the fixed image, and the like.
There is an influence of image patterns. For example, the relationship between the fixing temperature and the degree of dirt on the heating roller is as shown in the graph of FIG. As shown in the graph of FIG. 3, when the fixing temperature is within a certain range, the amount of stains is relatively small.
In the range of 0 (T1) to 240 (T2) ° C., the stain generation state becomes the allowable value D or less. On the other hand, when the temperature is high or low, the degree of contamination increases rapidly,
There is a problem that the web is easily soiled.

However, in the cleaning device shown in the above-mentioned conventional example, when the temperature is equal to or higher than the certain temperature set in the drive mechanism, the operation of winding the web is automatically performed. There is a problem that the stain cannot be removed when the heating roller is often stained at a relatively low temperature. Therefore, instead of the conventional example, as shown in JP-A-59-105671, it is conceivable that the cleaning effect is exhibited by constantly driving the web. However, if the web is always driven, the amount of consumption of the web increases, and there is a problem that the web is wasted.

If the timing for driving the web is not set properly, the toner remaining on the web at the end of fixing is melted at the time of the next fixing and transferred to the heating roller. The problem of dirtying the copy arises. Also, if a large amount of dirt remains on the web and the switch of the electronic copying machine is turned off, the toner is solidified, and when the switch of the electronic copying machine is turned on again, the solidified toner is heated by the heating roller. Since the surface of the heating roller is strongly rubbed, the problem of scratching the surface coating of the heating roller is likely to occur.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-described problem of a cleaning device using a web. The degree of dirt on the web is estimated, and a drive mechanism for the web is set according to the estimated dirt value. It is an object of the present invention to provide a device that can be used effectively by operating the web.

[0009]

The present invention provides two means.
The present invention relates to a fixing device in which three fixing rollers are arranged so as to face each other, and a cleaning means by a web is arranged for the fixing roller on the side where the toner carrying surface of the sheet comes into contact. In the cleaning device of the present invention, as a means for controlling the drive of the web, a control device having a function of predicting the degree of dirt of the web is provided, and the controller for predicting the dirt of the web is Based on the predicted value of the degree of soiling of the web in the control device, using the sheet size and the number of copies, and the information of the fixing temperature for the sheet that has been fixed at a temperature exceeding the allowable value of stain, It is configured to perform a web winding operation. Further, as the drive information for the cleaning device of the present invention, information on the paper size and information on the fixing temperature can be used, and in addition to such information, information on the image pattern and the image density can be used. ..

With the above-described structure, in the cleaning device of the present invention, the control device predicts the degree of dirt on the web and performs the operation of winding the web.
The web cleaning operation can be performed in good condition. Only when the web is soiled, the web of the soiled portion is wound up, so that the web is not wastefully used and toner offset can be prevented from occurring on the heating roller. Furthermore, by using the cleaning device of the present invention, the toner or the like attached to the heating roller is not transferred to the copy, and a good quality copy can be obtained.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A cleaning device for a fixing device according to the present invention will be described with reference to the illustrated example. The fixing device 1 of the present invention shown in FIG. 1 is, as in the case of the conventional heat roller type fixing device, a heating roller 2 provided with a heating source 3 such as a halogen lamp, and is pressed by the heating roller 2. Pressure roller 5
And are arranged. The heating roller 2 uses a roller core made of metal such as aluminum whose surface is coated with a material having heat resistance and releasability such as fluororesin, and the pressure roller 5 is made of aluminum or the like. A metal roller core whose surface is covered with a heat-resistant elastic body with a thickness of several mm is used.

In the fixing device 1, a pressure roller is supported by a biasing means such as a spring with respect to a heating roller supported by a frame of the fixing device through a bearing or the like. The nip pressure of a constant value can be set between the rollers. Then, the paper P carrying the toner T is passed between the two fixing rollers 2 and 5,
The toner is melted by heat and the melted toner is pressed against the paper so that a copy can be made. In the fixing device 1 configured as described above, the cleaning device 10 is arranged with respect to the heating roller 2 so as to perform the action of cleaning the toner adhering to the surface of the heating roller 2. In addition, paper peeling claws 6 and 7 are arranged in the paper discharge portion of the fixing roller so that the paper is peeled from the roller as in the case of a general heat roller type fixing device.

The heating roller 2 is provided with a temperature sensor 8 for measuring the temperature of the roller surface, as in the case of a conventional general fixing device. As the temperature sensor 8, a thermistor or any other temperature detecting member can be used, and the temperature detection information from the sensor is input to the control device of the electronic copying machine. Also, at the same time as turning on the main switch of the electronic copying machine, the heating source is energized,
When the heating roller 2 is preheated, the temperature of the heating roller is monitored by the sensor 8, and when the controller detects that the temperature has reached a certain temperature, the control panel of the electronic copying machine indicates that copying is possible. So that the copying operation can be performed. Further, as will be described later, the temperature sensor 8 outputs the information of the fixing temperature to the control device for the cleaning device when performing the fixing operation, and the control data for driving the web in the cleaning device. It is also used to obtain

As shown in the conventional example, the cleaning device 10 arranged for the heating roller presses the web 11 against the surface of the heating roller 2 by using the pinch roller 14, and the surface of the heating roller 2 is pressed. Is configured as a member for cleaning. The web 11 is supported by a feeding shaft 13 and a take-up shaft 12, and the take-up shaft 12 is driven by a drive motor 15 to take up a web with dirt such as toner, and a new web is applied to a heating roller. Make it correspond. As in the case of a conventional web cleaning device, a sheet-shaped member made of a heat-resistant non-woven fabric or the like is used as the web, and the web is impregnated with silicone oil or the like to form a heating roller. It is possible to make it difficult for the toner to adhere to the surface of the.
Further, the control device 20 is arranged with respect to the drive motor 15, and the control device 20 uses the information that predicts the dirt of the web 11 as will be described later.
Drive signal is output.

In the cleaning device 10, in order to drive the web 11, a control mechanism as shown in the block diagram of FIG. 2 can be constructed. In the block diagram of FIG. 2, the control device of the electronic copying machine can be used as the CPU of the control device 20, but in addition, a special control device is configured to drive the drive motor. You can also Then, the control device 20 outputs a drive signal to the motor driver 21 based on the estimated value of the degree of dirt of the web,
The motor driver 21 drives the drive motor by a predetermined pulse to move the web of the dirty portion to a position where it does not come into contact with the heating roller, so that the new web comes into contact with the heating roller.

Further, to the control device 20, a copy number signal 22, a paper size signal 23, and
Input the fixing temperature information 24 and the like. Among the information input to the control device, the information input to the control device of the electronic copying machine can be used as it is as the paper size signal 23 and the copy number signal 22. Further, in the present invention, the information of the paper feed tray selected at the time of copying and the cumulative value of the number of copies can be input to the control device 20, and the control operation can be performed based on such information. ..

In addition to the above two pieces of information, as the fixing temperature information 24 inputted to the control device, as shown in the graph of FIG. To be able to know the information that has performed the fixing action in. Therefore, in the information obtained as the fixing temperature 24, the information about the paper size and the number of copies when the fixing temperature is T1 or less and when the fixing temperature exceeds T2 is grasped and preset in the CPU. The degree of dirt on the web is estimated according to a program for detecting dirt on the web. Then, when the control device determines that the estimated value of the dirt on the web has reached the allowable limit, it outputs a drive signal to the motor driver 21 to drive the drive motor 15 to keep the web 11 constant. The length of the winding shaft 12 is made to wind.

Further, in the control device 20 of the present invention, in order to estimate the degree of dirt of the web, in addition to the above-mentioned various information, the information of the image pattern in the copy and the information of the image density are used. It is also possible. As the signal of the image pattern, the type of the document most often used is set in a place where copying is performed using the electronic copying machine, and, for example, a mode in which copying of a general document or the like is frequently performed, a table, When copying a graph or the like, the control factor in the control device can be set in correspondence with other general documents or drawings. In a general electronic copying machine, when the original contains many oblique lines and graphs, the heating roller is apt to be stained easily. In the case of type documents, etc. The degree of dirt is slightly reduced. Therefore, by adding the above-mentioned information and using it as the control information in the control device, the effect of estimating the dirt on the web can be accurately performed.

As described above, when the dirt on the web is estimated and the winding shaft is driven to wind the web for a certain length, the web wound around the winding shaft 12 is wound. It is necessary to control the driving time and the like for the winding shaft depending on the amount. Therefore, in the control device of the present invention, it is possible to estimate the amount of web wound on the winding side and control the time for driving the drive motor. The added information can be used. The information on the drive time of the drive motor is returned to zero when the web is replaced. In addition, the web stain information is reset when the web is driven.

[0020]

Since the cleaning device for the fixing device of the present invention is constructed as described above, the control device predicts the degree of dirt on the web and carries out the operation of winding the web. The web cleaning operation can be performed in good condition. Only when the web is soiled, the web of the soiled portion is wound up, so that the web is not wastefully used and toner offset can be prevented from occurring on the heating roller. Furthermore, by using the cleaning device of the present invention, the toner or the like attached to the heating roller is not transferred to the copy, and a good quality copy can be obtained.

[Brief description of drawings]

FIG. 1 is a side view showing a configuration of a fixing device of the present invention.

FIG. 2 is a block diagram showing a control device of the present invention.

FIG. 3 is a graph showing a relationship between a fixing temperature and a roller stain.

[Explanation of symbols]

1 fixing device, 2 heating roller, 5 pressure roller, 8 temperature sensor, 10 cleaning device, 11 web, 12 winding shaft, 13 feeding shaft, 15 drive motor, 20 control device,
21 motor driver, 22 copy number information,
23 Paper size information, 24 Fixing temperature information.

Claims (1)

[Claims] 1. Two fixing rollers are arranged facing each other,
In a fixing device in which cleaning means by a web is arranged with respect to a fixing roller on the side where a toner bearing surface of a sheet comes into contact, as a means for controlling drive of the web, the degree of dirt of the web is predicted. A control device having a function is provided, and in the control device that predicts the stain on the web, the size of the sheet, the number of copies, and information about the fixing temperature for the sheet that has been fixed at a temperature exceeding the allowable stain value. The cleaning device for the fixing device is characterized in that the web winding operation is performed based on a predicted value of the degree of soiling of the web in the control device.