JPH05323802A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain a stable image quality without decreasing efficiency in removing toner filming in the case of using a brush. CONSTITUTION:This device is provided with a toner filming device 35 with a loop brush 35A rotating while abutting on an intermediate transfer body 19. An encroaching amount to an intermediate transfer body 19 is changed according to the progress of the utilization of a loop brush 35A or the number of revolution of the loop brush 35A or abutting time is changed according to the starting stage of the removal of toner filming by means of the loop brush 35A to the subsequent stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a printer,
Regarding an image forming apparatus using an electrophotographic system such as FAX,
More specifically, the present invention relates to a toner filming removing device for an intermediate transfer member.

[0002]

2. Description of the Related Art In a color image forming apparatus which is one of image forming apparatuses, it is necessary to form toner images of three primary colors of subtractive color mixture on a recording paper in an overlapping manner. An example of a color image forming apparatus is, for example, Japanese Patent Laid-Open No. 52-73738.
As described in Japanese Patent Publication No. JP-A-2003-264, the toner image of each color component is formed on the photoconductor several times, and the toner image of each color component is sequentially transferred onto the recording paper one by one. There is an image forming apparatus that obtains an image.

However, such a color image forming apparatus is provided with a clamp mechanism for clamping the end portion of the recording paper to bring the recording paper into close contact with the photoconductor several times. In addition to being complicated, there is a problem that an image cannot be transferred to a clamp portion of the recording paper. Therefore, in order to solve such a problem, first, in the same manner as described above, the toner image for each color component is formed several times on the photoconductor, and the toner image for each color component is formed. On the other hand, there has been proposed an image forming apparatus configured to sequentially transfer the color toner images one by one to form a color toner image, and transfer the color toner images onto a recording sheet at once. Further, this intermediate transfer member is prepared for the next toner image transfer by scraping off the toner remaining on the surface by a cleaning member such as a cleaning blade after the transferred images are collectively transferred onto the recording paper. It is like this. In the proposed device, the intermediate transfer member is a belt member stretched by a driving roller and a driven roller, whereby the degree of freedom in spatial arrangement of the intermediate transfer member is increased, and the device can be downsized. The advantage is obtained.

[0004]

However, when a cleaning blade or the like is used for cleaning the intermediate transfer member, for example, if the intermediate transfer member is made of a thin film or the like, the intermediate transfer member may be affected by a change in environmental temperature. In some cases, the Young's modulus of the transfer member changes, and unevenness occurs on the surface of the intermediate transfer member, making the contact state with the cleaning blade unstable. Therefore, the toner that has not been scraped off by the cleaning blade remains on the surface of the transfer body as it is and forms toner filming. Such toner filming is mainly composed of an electrically insulating substance such as silica contained in the toner. Therefore, depending on the accumulated amount of toner filming, the electrical resistivity of the intermediate transfer member may be reduced. Since the transfer bias is changed, it becomes impossible to keep the transfer efficiency constant, and as a result, an abnormal image having an image dropout or the like is obtained.

Therefore, a structure has been proposed in which a rotating brush is brought into contact with the surface of the intermediate transfer member to remove the toner filming. However, in cleaning the intermediate transfer member with such a brush, the toner filming removing member such as the brush deteriorates with time, and specifically, abrasion or hair fall occurs, and the toner filming removal efficiency is increased. May decrease. In addition to this, if the brush is driven by a uniform number of times, it takes a long time to remove it when the layer thickness of toner filming is large. The removal efficiency will decrease.

Therefore, in view of the above-mentioned conventional image forming apparatus, and in particular, the problem in removing toner filming of an intermediate transfer member, an object of the present invention is stable without lowering the toner filming removal efficiency when a brush is used. An object of the present invention is to obtain an image forming apparatus capable of obtaining the desired image quality.

[0007]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides an image carrier for carrying a toner image which is an electrostatic latent image visualized, and a toner image transferred from the image carrier. In an image forming apparatus having an intermediate transfer body that is driven to rotate while being carried, the toner image is conveyed toward the process of transferring the toner image to a recording medium, and is provided so as to be abuttable and rotatable on the intermediate transfer body. Then, according to the elapse of the contact period with the intermediate transfer member, the contact condition with the intermediate transfer member is set so that the brush is displaced in such a direction that the brush bites into the intermediate transfer member. It is characterized by having.

Further, the present invention is characterized in that the toner filming removing member is provided so as to be rotatable in the forward and reverse directions.

Further, the present invention is characterized in that the toner filming removing member is rotated in the reverse direction at the time when the contact period with the intermediate transfer member has passed a predetermined period.

The present invention is characterized in that the toner filming removing member changes the rotation speed at the time when the toner filming removal member comes into contact with the intermediate transfer member and starts rotation, and the rotation speed other than this time. There is.

Further, according to the present invention, the toner filming removing member changes the rotational speed in accordance with the contact period with the intermediate transfer member at the beginning of the period and the period after the period. It is characterized by being.

Further, according to the present invention, the toner filming removing member sets the contact time with respect to the intermediate transfer member at the beginning of the contact period and the time after the contact period according to the contact period with the intermediate transfer member. It is characterized by being changed.

[0013]

According to the present invention, as the removal period of the toner filming removing member elapses, the amount of bite into the intermediate transfer member is increased and the reduction of the amount of scraping of toner filming can be suppressed. Further, according to the present invention, hair fall in one direction is corrected by rotating the toner filming member forward and backward. Further, according to the present invention, when the removal period by the toner filming member has passed a predetermined period,
By rotating in the opposite direction, the fallen hair can be raised and corrected. Furthermore, according to the present invention, the number of revolutions can be changed as the removal period by the toner filming member becomes longer, and the reduction in removal efficiency due to hair collapse or the like is compensated. According to the present invention, the toner filming removing member is rotated at a high rotation speed at the stage when the toner filming removal member starts to contact the intermediate transfer member, and thereafter, the rotation speed is set to be equal to or lower than that speed to start contacting the intermediate transfer member. At this stage, roughly remove toner filming, and at the stage when a certain time has elapsed after contact, set the rotation speed lower than the above rotation speed to gradually remove toner filming In addition, the toner filming can be removed carefully and damage to the intermediate transfer member can be suppressed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the embodiments of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic configuration diagram of the entire copying machine in which a belt (hereinafter referred to as an intermediate transfer belt) is used as an intermediate transfer member in a color copying machine which is one of image forming apparatuses. 2 is an enlarged view around the photoconductor / intermediate transfer belt shown in FIG. Below is the configuration of this device
The operation will be described.

The color copying machine comprises a color image reading device 1 and a color printer 2 forming a printer section, which will be described later. Among these, the color image reading device (hereinafter referred to as a color scanner) 1 is a copy of an original 3. An image is formed on the color sensor 7 through the illumination lamp 4, the mirrors 5-1, 5-2, 5-3, and the lens 6, and the color image information of the document is, for example, blue (Blue).
e), green, and red are read for each color-separated light and converted into an electric image signal. Note that these decomposed lights will be referred to as B, G, and R in the following description for convenience. Then, B, G, obtained with this color scanner 1,
Based on the R color separation image signal intensity level, the image processing unit
Perform color conversion processing (not shown), and black (hereinafter,
Color image data of cyan (same as C), magenta (same as M), and yellow (same as Y) are obtained.

A color image recording apparatus described below
(Hereinafter referred to as a color printer) 2, BK,
Visualization is performed using C, M, and Y toners, and these toner images are superposed to form a four-color full-color image.

Next, the outline of the color printer 2 will be described. The writing optical unit is a unit that converts the color image data from the color scanner 1 into an optical signal and performs optical writing corresponding to the original image.
-The laser beam from 1 is scanned through the polygon mirror 8-2 rotated by the drive motor 8-3, and the fθ lens 8-
4. The scanning light is guided to the photoconductor drum 9 by the reflecting mirror 8-5 to form an electrostatic latent image.

The photoconductor drum 9 rotates counterclockwise as indicated by the arrow, around which a photoconductor cleaning unit (including a pre-cleaning static eliminator) 10 and a static elimination lamp 1 are provided.
1, charger 12, potential sensor 13, BK developing device 14,
The C developing device 15, the M developing device 16, the Y developing device 17, the development density pattern detector 18, the intermediate transfer belt 19 and other devices for executing the electrophotographic copying process are arranged. Each developing device is a developing sleeve that rotates so that the developer faces the photoconductor 9 in order to develop the electrostatic latent image in FIG.
(14-1, 15-1, 16-1, 17-1) and a developing paddle (14-2, 15-) that rotates to draw up and agitate the developer.
2, 16-2, 17-2) and a toner concentration detection sensor (14-3, 15-3, 16-3, 17-3) of the developer. And the order of development operation (color image formation order)
The case where BK, C, M and Y is described below. However, the image forming order is not limited to this. When the copy operation is started, the color scanner 1 starts reading BK image data at a predetermined timing, and based on this image data, optical writing by laser light is performed. The latent image formation starts (hereinafter, the electrostatic latent image based on the BK image data is referred to as BK latent image. The same applies to C, M, and Y). In order to develop the BK latent image from the front end thereof, the developing sleeve 14-1 is started to rotate before the latent image front end reaches the developing position of the BK developing device 14 to develop the BK latent image with BK toner. develop. After that, the developing operation of the BK latent image area is continued, but when the rear end portion of the BK latent image passes the BK developing position, the developing operation is disabled. This is completed at least before the leading edge of the C latent image by the next C image data arrives.

Now, the BK toner image formed on the photoconductor 9 is transferred to the surface of the intermediate transfer belt 19 which is driven at the same speed as the photoconductor (hereinafter, the toner image transfer from the photoconductor to the intermediate transfer belt will be described). (Belt transfer). Belt transfer
This is performed by applying a predetermined bias voltage to the transfer bias roller 20 while the photoconductor 9 and the intermediate transfer belt 19 are in contact with each other. The intermediate transfer belt 19 has a photosensitive member 9
The toner images of BK, C, M, and Y that are sequentially formed are sequentially aligned on the same surface to form a belt transfer image of four-color superimposition, and then are collectively transferred to a transfer paper. The structure and operation of this intermediate transfer belt unit will be described later.

By the way, on the side of the photoreceptor 9, the process proceeds to the C process after the BK process, but the C image data reading by the color scanner 1 is started at a predetermined timing, and the C latent image is formed by the laser light writing by the image data. To do. The C developing device 15 starts rotating the developing sleeve 15-1 to the developing position after the trailing edge of the BK latent image has passed and before the leading edge of the C latent image reaches. The C latent image is developed with C toner. After that, the development of the C latent image area is continued, but when the trailing edge of the latent image passes, the C developing sleeve 15-
1 Cut the top of the agent. This is also completed before the leading edge of the next M latent image arrives. It should be noted that the steps of M and Y are the same as the steps of BK and C described above since the operations of reading image data, forming a latent image, and developing are the same as those of step BK and C.

Next, the intermediate transfer belt unit will be described.

The intermediate transfer belt 19 includes a driving roller 21,
It is stretched around the belt transfer bias roller 20 and the driven roller group, and is driven and controlled by a drive motor (not shown) as described later.

The belt cleaning unit 22 is shown in FIG.
As shown in, brush roller 22-1, rubber blade 22
-2, and the contact and separation mechanism 22-3 from the belt, etc., and after transferring the BK image of the first color to the belt, 2.
While transferring the third and fourth colors on the belt, the contact / separation mechanism 22-3
It is designed to be separated from the belt surface.

The paper transfer unit 23 includes a paper transfer bias roller 23-1, a roller cleaning blade 23-2,
And a belt contact / separation mechanism 23-3 and the like. The bias roller 23-1 is normally separated from the surface of the belt 19, but when transferring the four-color superposed images formed on the surface of the intermediate transfer belt 19 to the transfer paper all at once, the timing is set and the contact / separation mechanism is set. The toner image is transferred onto the paper while being pressed by 23-3 and applying a predetermined bias voltage by the roller 23-1. The transfer paper 24 is shown in FIG.
As shown in FIG.
Thus, the four-color superimposed image on the surface of the intermediate transfer belt is fed at the timing when the front end portion reaches the paper transfer position.

The movement of the intermediate transfer belt 19 is 1
The following three types of operation methods are possible after the belt transfer of the BK toner image of the color is completed up to the rear end. One of them can be used, or it can be used efficiently depending on the copy size (copy speed etc.). It operates by combining various methods.

1) -Constant speed forward movement method This is a method in which the transfer belt continues to move at a constant speed even after the toner image of the first color is transferred. In the case of this method, The image processing is performed with the timing set so that the leading edge of the image of the toner image of the next color that is subjected to the visible image processing on the side of the photoconductor 9 and the leading edge of the image on the intermediate transfer belt 19 coincide with each other. And the process for that is as follows. Even after the BK toner image is transferred onto the belt, it keeps moving forward at a constant speed. When the front end position of the BK image on the surface of the belt 19 reaches the belt transfer position of the contact portion with the photosensitive member 9 again, the front end portion of the next C toner image on the photosensitive member 9 side is exactly at that position. In addition, the image is formed with a timing. As a result, the C image is accurately aligned with the BK image and is transferred onto the intermediate transfer belt 19 in a superimposed manner. After that, the same operation is performed to proceed to the M and Y image process.
Obtain a belt transfer image with color overlay. Following the fourth color Y toner image belt transfer process, the four color superposed toner images on the belt surface are collectively transferred to the transfer paper 24 as described above while moving forward.

2) Skip forward method This is faster than the case where the transfer belt is separated from the photosensitive member after the toner image of the first color is transferred and the toner image of the first color is transferred. Then, it is moved in the same direction as before, and when a predetermined amount is moved, it is switched to the initial moving speed and brought into contact with the photosensitive member again. This method is performed, for example, when the length of the image transferred is short with respect to the length of the transfer belt, and it is possible to prevent the cycle time for image formation on the photoconductor side from increasing. The process for this is as follows. When the belt transfer of the BK toner image is completed, the belt 19 is separated from the surface of the photoconductor 9 and is skipped at high speed in the forward direction, and after moving a predetermined amount, the initial forward speed is restored. After that, the belt 19 is again brought into contact with the photosensitive member 9. Then, when the BK image front end position on the surface of the belt 19 reaches the belt transfer position again, an image is formed on the photosensitive member 9 side at a timing so that the front end portion of the next C toner image comes to that position. There is. As a result, the C image is transferred onto the belt while being accurately aligned with the BK image. After that, the same operation is performed to proceed to the M and Y image process to obtain a belt transfer image of four colors. Following the Y color toner image belt transfer process for the fourth color, the four color superimposed toner images on the surface of the belt 19 are collectively transferred onto the transfer paper 24 at the same forward speed.

3) Reciprocating (quick return) method This is to separate the transfer belt from the photoconductor after the toner image of the first color is transferred, and to move the transfer belt in the reverse direction at a higher speed than before. Move and wait until the position of the previously transferred toner image matches the position of the toner image of the next color carried on the photoconductor, and then bring the transfer belt into contact with the photoconductor again. In this method, the movement is started in the same direction as the photoconductor, and this operation is continued until the transfer of the toner image of the final color. In this method, when the image position on the transfer belt is adjusted to the image position on the photoconductor, the transfer belt is not moved in the forward direction, but only the amount of movement that has been progressed is reversed. Considering that the movement amount of the transfer belt does not have to be secured so much, the control is simplified, and the process for this is as follows. When the belt transfer of the BK toner image is completed, the belt 19 is separated from the surface of the photoconductor 9, and the forward movement is stopped, and at the same time, the belt 19 is returned at a high speed in the opposite direction.

In the return, the BK image front end position on the surface of the belt 19 passes the position corresponding to the belt transfer in the opposite direction, further moves a preset distance, and then is stopped to be in a standby state. Next, when the front end of the C toner image on the side of the photoconductor 9 reaches a predetermined position before the belt transfer position, the intermediate transfer belt 19 is restarted in the forward direction. Belt 1 again
9 is brought into contact with the surface of the photoreceptor 9 again. Also in this case, the C image is transferred under the condition that it is accurately overlapped with the BK image on the surface of the belt 19. After that, the same operation is performed to proceed to the M and Y image process to obtain a belt transfer image of four colors. Subsequent to the belt transfer process of the Y toner image of the fourth color, the toner is moved forward at the same speed without returning, and the four-color superimposed toner image on the surface of the belt 19 is collectively transferred onto the transfer paper 24.

The transfer paper 24 on which the four-color superposed toner images are collectively transferred from the surface of the intermediate transfer belt is conveyed to a fixing device 28 by a paper conveying unit 27 in FIG. 1, and the fixing roller 28 is controlled to a predetermined temperature.ー 1 and pressure roller 2
The toner image is fused and fixed at 8-2 and is carried out to the copy tray 29 to obtain a full-color copy.

The photosensitive member 9 after the belt transfer is the photosensitive member cleaning unit 10 (pre-cleaning static eliminator 10-
The surface is cleaned by 1, the brush roller 10-2 and the rubber blade 10-3), and the charge is uniformly discharged by the discharge lamp 11.

Further, the intermediate transfer belt 19 after the toner image is transferred onto the transfer paper 24 is cleaned by the cleaning unit 22.
Is pressed again by the contacting / separating mechanism 22-3 to clean the surface. For repeat copy, color scanner 1
And the image formation on the photoconductor 9 is performed on the first Y (4
Following the (color) image process, the process proceeds to the second BK (first color) image process at a predetermined timing. Further, in the intermediate transfer belt 19, the BK toner image of the second sheet is belt-transferred to the area where the surface is cleaned by the cleaning unit 22, following the process of collectively transferring the first four-color superimposed image to the transfer paper. To do so. After that, the same operation as the first sheet is performed.

In FIG. 1, the transfer paper cassette 3
Transfer papers of various sizes are stored in 0, 31, 32, and 33, and are fed toward the registration roller 26 at a timing from a storage cassette of the size paper designated by the operation panel (not shown). Paper is transported. Note that reference numeral 3
Reference numeral 4 denotes a manual paper feed tray for OHP paper or thick paper.

Up to this point, the copy mode for obtaining four full colors has been described, but in the case of the three-color copy mode and the two-color copy mode, the same operation as described above is performed for the designated color and the number of times. .. In the case of the single-color copy mode, only the developing device of that color is brought into the developing operation (agent standing) state until the predetermined number of sheets are finished, and the intermediate transfer belt 19 contacts the surface of the photoconductor 9. Continue to drive in the forward direction-constant speed drive, and belt cleaner 22
The copy operation is performed in the state of being in contact with 9.

On the other hand, as shown in FIG. 3, a toner filming removing device 35 is arranged on the intermediate transfer belt 19 at a position facing one of the pulleys around which the intermediate transfer belt 19 is wound. In this embodiment, the toner filming removing device 35 is a rotatable stainless steel loop brush 35A.
The brush 35A is made of, for example, a stainless wire having a thickness of 50 μm,
The bristles are flocked in a loop shape so as to increase the area when they come into contact with the intermediate transfer belt 19,
The loop assembly density is set to 600 loops per square inch. Further, the loop brush 35A is supported by the free end of a swing member (not shown) in FIG. 3 so as to be able to come into contact with and separate from the intermediate transfer belt 19, and is normally separated from the intermediate transfer belt 19, and When they come into contact with each other, the intermediate transfer belt 19 is designed to be bitten by about 1 mm. In the toner filming removing device 35, the loop brush 35A is brought into contact with the intermediate transfer belt 19 every time copying is performed 1000 times, for example, and the loop brush 35A is opposed to the intermediate transfer belt 19 at a rotation speed of 500 rpm. The surface of the intermediate transfer belt 19 is rubbed by rotating in a relative direction at a position. Of course, when the toner filming removing operation is being performed, the above-described image forming process is not being performed.

By the way, the toner filming device 35
As the number of times the loop brush 35A is brought into contact with the intermediate transfer belt 19 increases, as time-dependent changes, hair collapse, fiber fraying, foreign matter adhesion, or the like occurs. In the present embodiment, such a situation is avoided because the contact pressure in the case of contact may change or the part to be contacted may not contact. That is, the loop brush 35A measures the contact time with the intermediate transfer belt 19, and changes the contact condition with the intermediate transfer belt 19 according to the elapsed time. The contact condition is as follows. As shown in FIG. 4, as the contact time elapses, the amount of bite into the intermediate transfer belt 19 is changed to increase.

Since this embodiment has the above-mentioned configuration,
The number of batch transfer of toner images by the intermediate transfer belt 19 is 1
When it reaches 000 times, the toner filming removing device 35
The loop brush 35 </ b> A comes into contact with the intermediate transfer belt 19. The contact time of the loop brush 35A is measured by a timer (not shown), and the bite amount of the loop brush 35A into the intermediate transfer belt 19 is corrected according to the elapsed time. According to this embodiment, the intermediate transfer belt 1
Even if the contact condition with the intermediate transfer belt 19 changes due to the change of the loop brush 35A with the passage of time after the contact time with the contact belt 9 has changed and the contact condition with the intermediate transfer belt 19 changes. Since the conditions for scraping off the toner filming such as the contact pressure can be made constant, it is possible to prevent the toner filming removal efficiency from decreasing.

In the toner filming removing device 35 described above, the loop brush 35A is configured to be rotatable in the forward and reverse directions in order to prevent the deterioration of the toner filming removal efficiency due to hair collapse of the loop brush 35A and fiber fraying. After a predetermined time such as 30 minutes, for example, the time of contact with the intermediate transfer belt 19 is reversed, the rotation direction may be reversed to correct hair collapse and fiber fraying. In this case, a DC motor is used as a drive source for the loop brush 35A, and the rotation direction is switched by reversing the power supply polarity to this motor, and the drive source on the intermediate transfer belt 19 side is also used. , The belt moving direction is reversed.

On the other hand, in the present invention, when the number of rotations of the loop brush 35A described above is always the same, it takes a relatively long time to remove it depending on the thickness of the toner filming. Focusing attention, the removal of toner filming is completed in a short time. That is, at a stage when not much time has passed after the start of toner filming removal, the toner filming is roughly removed to remove a large amount, and when the time has passed, the toner filming is gradually removed. I am supposed to do it. This is carried out by scraping a large amount in consideration of the small chance of rubbing the surface of the intermediate transfer belt 19 and the loop brush 35A in the removal operation start stage, and in other words, a stage after a lapse of time from the start of the removal operation, in other words, At a stage where the loop brush 35A is in danger of rubbing the intermediate transfer belt 19 due to the removal of the toner filming, the toner filming is removed surely and gradually by carefully scraping the intermediate transfer belt 19 and the intermediate transfer. Even if the belt is rubbed, the intermediate transfer belt 19
This is to reduce damage to the surface of the. Therefore, the loop brush 35A is rotated at a high speed at the start stage of the toner filming removal operation, and the rotation speed is set to be equal to or lower than this rotation speed after a predetermined time elapses due to this rotation. The present inventor has conducted an experiment on the relationship between the rotation time and the rotation speed of the loop brush 35A. As a result, the moving speed of the intermediate transfer belt is set to 700 mm / s at the start stage of the toner filming removal operation. Toner filming is removed at a rotation speed of 800 / rpm, and one minute after the removal operation is started, the moving speed of the intermediate transfer belt 19 is set to 180 mm / rpm, and the loop brush 35
When the number of revolutions of A was 500 rpm, the time required to completely remove the toner filming was completed in 5 minutes, and it was possible to shorten the time by 2 minutes compared with 7 minutes required for a constant number of revolutions. Note that the change in the moving speed of the intermediate transfer belt in this case is rough at the stage of starting the toner filming removal operation,
And in order to be able to remove a large amount,
This is to prevent careful scraping and damage to the intermediate transfer belt 19 after a predetermined time has elapsed. Further, the predetermined time set as the timing for changing the number of rotations is set in consideration of the difference in the toner filming deposition condition depending on the toner forming the toner filming or the material of the belt side to which the toner filming is attached. In the case of, the time is set to correspond to the time when the loop brush 35A does not rub the intermediate transfer belt 19.

Next, in the present invention, it is intended to eliminate the adverse effects on the toner filming removal efficiency, such as the above-described hair collapse and fiber fraying, which appear as a change with time of the loop brush, by changing the rotational speed or the contact time. It is also becoming. That is, FIG. 5 is a diagram showing the rotational speed characteristic of the toner filming device of the image forming apparatus according to another embodiment of the present invention. In this diagram, the rotational speed of the loop brush 35A is the intermediate transfer belt 19 The rotation speed is increased as the contact time with the roller elapses. 6 is a diagram showing a characteristic relating to the contact time in the toner filming removing device 35 of the image forming apparatus according to another embodiment of the present invention. In this diagram, the loop brush for the intermediate transfer belt 19 is shown. The contact time of 35A is made longer as the toner filming removal operation progresses.

In the embodiment in which such characteristics are set, even when the loop brush 35A changes with time, the intermediate transfer belt 19 remains unchanged.
It is possible to increase the number of times of rubbing of the loop brie 35A with respect to the above so as not to lower the removal efficiency of toner filming.

[0043]

As described above, according to the present invention, when the toner filming is removed by the brush abutting on the intermediate transfer member, the contact condition of the brush is an intermediate value depending on the lapse of the removal time by the brush. Since the amount of bite into the transfer member is changed so as to increase, it is possible to prevent the defective scraping of the toner filming due to the change of the contact condition due to hair collapse or fiber fraying. In addition, hair collapse and fiber fraying can be corrected by setting the forward and reverse rotation of the brush. Therefore, it is possible to prevent the removal efficiency of toner filming from changing due to a change with time that occurs when a brush is used, and it is possible to obtain good image quality without hindering the transfer efficiency of the intermediate transfer member.

Further, according to the present invention, the number of rotations of the brush is changed between the step of starting the toner filming removal operation and the lapse of a predetermined time after the start of the operation. After a lapse of a predetermined time, the toner filming can be surely removed by carefully and gradually scraping the toner film, and damage to the intermediate transfer member can be prevented. Therefore, by reliably removing the toner filming, it is possible to suppress the change in the transfer efficiency of the intermediate transfer member and obtain a good image quality. According to the present invention, the rotational speed of the brush or the contact time of the brush with the intermediate transfer member is changed according to the change with time of the brush. Therefore, even if the change with time occurs, the intermediate transfer in that state is performed. It is possible to increase the number of times of rubbing against the body so as not to reduce the efficiency of removing toner filming. Therefore, also by this, by reliably removing the toner filming, it is possible to suppress the change in the transfer efficiency of the intermediate transfer member and obtain good image quality.

[Brief description of drawings]

FIG. 1 is a layout diagram showing a schematic configuration of a color copying apparatus which is one of image forming apparatuses of the present invention.

FIG. 2 is a photoconductor in the color copying apparatus shown in FIG.
FIG. 6 is an enlarged view of an area around an intermediate transfer belt.

3 is a schematic layout diagram showing a toner filming removing device for an intermediate transfer belt in the image forming apparatus shown in FIG.

FIG. 4 is a diagram for explaining characteristics of the toner filming removing device shown in FIG.

FIG. 5 is a diagram for explaining another characteristic of the toner filming removing device shown in FIG.

6 is a diagram for explaining another characteristic of the toner filming device shown in FIG.

[Explanation of symbols]

 1 Color Image Reading Device (Color Scanner) 2 Color Image Recording Device (Color Printer) 9 Photosensitive Drum 10 Photosensitive Cleaning Unit 19 Intermediate Transfer Belt 35 Toner Filming Removal Device 35A Loop Brush

Claims (6)

[Claims] 1. A toner image carrying an electrostatic latent image visualized toner image carrying member, and the toner image transferred from the image carrying member being carried in rotation while being rotatably driven, the toner image In an image forming apparatus having an intermediate transfer body that conveys the intermediate transfer body to a recording medium, the image forming apparatus is provided so as to be capable of contacting the intermediate transfer body and rotatably, depending on a lapse of the contact period with the intermediate transfer body. An image forming apparatus is provided with a toner filming removing member whose contact condition with the intermediate transfer member is set so that the brush is displaced in a direction in which the brush bites into the intermediate transfer member. 2. The image forming apparatus according to claim 1, wherein the toner filming removing member is provided so as to be rotatable in the forward and reverse directions. 3. The image forming apparatus according to claim 1, wherein the toner filming removing member is rotated in a reverse direction at a time point when a contact period with the intermediate transfer member has elapsed for a predetermined period. 4. The image forming apparatus according to claim 1, wherein the toner filming removing member changes a rotation speed at a time point when the toner filming removal member comes into contact with the intermediate transfer member and starts rotation, and a rotation speed number other than this time point. Image forming device. 5. The image forming apparatus according to claim 4, wherein the toner filming removing member changes the rotational speed at an initial stage of the contact period with the intermediate transfer member and at a later stage thereof. An image forming apparatus adapted to change. 6. The image forming apparatus according to claim 1, wherein the toner filming removing member has an initial contact period and a subsequent contact period depending on a contact period with the intermediate transfer member. An image forming apparatus adapted to change the contact time with an intermediate transfer member.