JP3050691B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic method such as a facsimile, and more particularly, to an image forming apparatus having a belt-shaped carrier that carries a toner image and conveys the toner image to the next process.

[0002]

2. Description of the Related Art Conventionally, as a device for cleaning toner adhered like a photoreceptor or an intermediate transfer member by the next image forming cycle, a blade cleaning method of pressing an edge of urethane rubber to scrape off the toner, a hair, etc. There is a fur brush cleaning method using a brush. In particular, the blade cleaning method is mechanically simple,
Moreover, since it is inexpensive, it is widely used.

However, in the blade cleaning method,
When minute toner, toner melted by heat or pressure, etc. is generated on the photoconductor or intermediate transfer body, it cannot be completely removed with the blade alone, and the filming layer is gradually formed, so the transfer performance is reduced and the image quality is reduced. Poor quality.

[0004] In particular, in the case of a double transfer system using an intermediate transfer member as an image carrier, the transfer efficiency is greatly reduced even if a slight filming layer is formed. Further, when a filming layer is formed on the image carrier, the friction coefficient between the blade and the image carrier increases, so that when the counter blade method is used, the blade is likely to be involved. When the image carrier is a belt member stretched by a belt driving roller and a driven roller, the belt driving roller runs idle due to an increase in the frictional force between the blade and the image carrier.

Therefore, for example, Japanese Patent Application Laid-Open No. Hei.
As disclosed in Japanese Patent Application Laid-Open Publication No. HEI 2 (1990) -1990, a filming cleaning roller is used as a rubbing member, and the filming cleaning roller is rubbed against an image carrier to remove a filming layer.
As disclosed in Japanese Patent No. 262180, there is a technique in which a cleaning roller is used as a rubbing member, and the timing at which the cleaning roller rubs the image carrier is set to once for several copies.

[0006]

However, in the above technique, when the toner filming layer is removed by the cleaning roller, there is a problem that the image carrier is rubbed too much. Further, in the above-described technique, the filming generation state changes depending on the use conditions of the copier and the like, so that it is not always possible to cope with all use environments.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, to prevent the blade from being rolled up due to the formation of a filming layer and to prevent idling of a belt driving roller, and to ensure stable image formation for a long period of time. Is to provide.

[0008]

In order to achieve the above object, the present invention has one of the following constitutions. The invention according to claim 1 is a belt-shaped carrier that is stretched between a belt driving roller and a driven roller, carries a toner image on a surface thereof, and conveys the toner image by being rotationally driven;
In an image forming apparatus having a cleaning member for removing residual toner on the belt-shaped carrier and a detachable rubbing member for polishing a surface of the belt-shaped carrier, the cleaning member may be a belt-shaped carrier. Pressurizing force adjusting means for pressing and changing the pressurizing force, a plurality of rotational speed detecting means for respectively detecting the rotational speeds of the belt driving roller and the driven roller, and a plurality of rotational speeds obtained by the plurality of rotational speed detecting means. And a control means for controlling the operation of the pressing force adjusting means and / or the rubbing member based on the output signal of the comparing circuit.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the control means determines that the moving speed of the outer periphery of the driven roller calculated from the outer diameter and the number of rotations of the driven roller is equal to the belt driving speed. When the moving speed of the outer periphery of the belt driving roller calculated from the outer diameter and the number of rotations of the roller is smaller than the moving speed of the belt driving roller, the pressing force is reduced from a reference value, and when both moving speeds are equal, the pressing force is controlled to the reference value. And

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the belt-shaped carrier and / or
Or a temperature detecting means for detecting a temperature of the cleaning member, and a humidity detecting means for detecting humidity near the belt-shaped carrier, wherein the temperature detecting means and the humidity detecting means detect the humidity. The pressure reduction amount is changed.

According to a fourth aspect of the present invention, in the image forming apparatus of the first, second or third aspect, the control means makes the moving speed of the outer periphery of the belt driving roller smaller than the moving speed of the outer periphery of the driven roller. After that, the execution of the polishing operation by the rubbing member is controlled.

[0012] The invention according to claim 5 is the invention according to claims 1, 2, 3, and 4.
Alternatively, in the image forming apparatus described in Item 4, the cleaning member is an elastic blade that abuts in a counter direction with respect to a rotation direction of the belt-shaped carrier.

The invention according to claim 6 is the invention according to claims 1, 2, 3
Or in the image forming apparatus according to 4, the rubbing member,
The brush roller is made of a metal loop fiber. The invention according to claim 7 is the invention according to claim 1, 2, 3, or 4.
In the image forming apparatus described above, the rubbing member is a brush roller made of conductive resin loop fibers.

[0014] The invention according to claim 8 is the invention according to claims 1, 2, and 3.
8. The image forming apparatus according to 3, 4, 5, 6, or 7, wherein the cleaning member is capable of coming into contact with and separating from the belt-shaped carrier, and the cleaning member is operable to polish the belt-shaped carrier with the rubbing member. The belt-shaped carrier is rotated while the cleaning member is separated from the belt-shaped carrier.

According to the ninth aspect of the present invention, there is provided the first, second, and third aspects.
8. The image forming apparatus according to 3, 4, 5, 6, or 7, wherein the cleaning member is capable of coming into contact with and separating from the belt-shaped carrier, and the rubbing member is moved in a rotation direction of the belt-shaped carrier. When the cleaning member is disposed downstream from the cleaning member and upstream from a process unit where the toner image is transferred to the belt-shaped carrier, and the cleaning member is in contact with the belt-shaped carrier, The polishing operation is performed by bringing the rubbing member into contact with the belt-shaped carrier.

[0016]

According to the first aspect of the present invention, there is provided a pressing force adjusting means for pressing the cleaning member against the belt-shaped carrier to change the pressing force, and a plurality of pressure detecting means for detecting the rotational speeds of the belt driving roller and the driven roller. A rotation speed detection unit, a comparison circuit for comparing a plurality of detection values obtained by the plurality of rotation speed detection units, and control for controlling operation of the pressing force adjustment unit and / or the rubbing member based on an output signal of the comparison circuit. Means, the idling of the belt drive roller is detected, and the operation of the pressing force adjusting means and / or the rubbing member is controlled based on the detection result.

According to the second aspect of the present invention, the moving speed of the outer periphery of the driven roller calculated from the outer diameter and the rotation speed of the driven roller is equal to the outer peripheral speed of the belt driving roller calculated from the outer diameter and the rotation speed of the belt driving roller. When the moving speed is lower than the reference speed, the pressing force is reduced below the reference value, and when the moving speeds of both are equal, the pressing force is controlled to the reference value.

According to the third aspect of the present invention, the amount of decrease in the pressing force for pressing the cleaning member against the belt-shaped carrier is changed according to the detection results of the temperature detecting means and the humidity detecting means.

According to the fourth aspect of the present invention, after detecting that the moving speed of the outer periphery of the belt driving roller is lower than the moving speed of the outer periphery of the driven roller, the execution of the polishing operation by the rubbing member is controlled. .

According to the fifth aspect of the present invention, since the cleaning member is an elastic blade abutting in the counter direction with respect to the rotation direction of the belt-shaped carrier, reliable cleaning can be performed with only one blade. .

According to the sixth aspect of the present invention, since the rubbing member is a brush roller made of a metal loop fiber,
Filming is efficiently removed.

According to the seventh aspect of the present invention, since the rubbing member is a brush roller made of conductive resin loop fibers, the cost is reduced.

According to the eighth aspect of the present invention, the cleaning member can be brought into contact with and separated from the belt-shaped carrier, and during the operation of polishing the belt-shaped carrier by the rubbing member,
Since the belt-shaped carrier rotates while the cleaning member is separated from the belt-shaped carrier, the load applied to the cleaning member is reduced.

According to the ninth aspect of the present invention, the cleaning member can be brought into contact with and separated from the belt-shaped carrier, and the rubbing member is located downstream of the cleaning member in the rotation direction of the belt-shaped carrier. Further, the toner image is arranged on the upstream side of the process section where the toner image is transferred to the belt-shaped carrier, and when the cleaning member is in contact with the belt-shaped carrier, the rubbing member is in contact with the belt-shaped carrier. Since the polishing operation is performed,
Filming is also removed during image formation.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a belt-shaped carrier in the present invention is an intermediate transfer belt will be described below with reference to the drawings. First, a schematic configuration of a color copying machine suitable for carrying out the present invention will be described with reference to FIG. 1, and a configuration around a photosensitive drum and an intermediate transfer belt will be described with reference to FIG.

In FIG. 1, a color image reading apparatus (hereinafter, referred to as a color scanner) 1 forms an image of a document 3 on a color sensor 7 via an illumination lamp 4, a mirror group 5, and a lens 6. Then, the color image information of the original is read, for example, for each color separation light of blue (hereinafter, referred to as B), green (hereinafter, referred to as G), and red (hereinafter, referred to as R), and is converted into an electric image signal. .

B, G, R obtained by the color scanner 1
A color conversion process is performed by an image processing unit (not shown) based on the color separation image signal intensity level of black (hereinafter B).
K, cyan (hereinafter, referred to as C), magenta (hereinafter, referred to as M), and yellow (hereinafter, referred to as Y) color image data are obtained.

This is converted into BK, BK by a color image recording device (hereinafter referred to as a color printer) 2 described below.
Visualization of C, M, and Y is performed, and these are superimposed to obtain 4 images.
A full-color image is formed.

Next, an outline of the color printer 2 will be described with reference to FIGS. The writing optical unit 8 converts the color image data from the color scanner 1 into an optical signal, performs optical writing corresponding to the original image, and forms an electrostatic latent image on the photosensitive drum 9.

The photosensitive drum 9 rotates in the counterclockwise direction as indicated by the arrow, and around the photosensitive drum 9, a photosensitive member cleaning unit (including a pre-cleaning static eliminator) 10, a static elimination lamp 11, a charger 12, a potential sensor 13, BK developing device 14, C developing device 15, M developing device 16, Y developing device 17,
A development density pattern detector 18, an intermediate transfer belt 19, and the like are arranged.

Each developing device includes a developing sleeve (14-1, 15-1, 16-1, 17-1) which rotates so that a developer faces the photosensitive drum 9 in order to develop an electrostatic latent image. A developing paddle (14-2, 15-2, 16-2, 17-2) which rotates to pump up and agitate the developer; and a toner concentration detecting sensor (14-3, 15-3, 16) of the developer. −
3, 17-3) and the like.

Order of developing operation (color image forming order)
Will be described below using examples of BK, C, M, and Y. However, the image forming order is not limited to this. When the copying operation is started, reading of the BK image data is started at a predetermined timing by the color scanner 1, and based on this image data, light writing by a laser beam and formation of a latent image are started (hereinafter, static image formation by the BK image data). The electric latent image is called a BK latent image, and the same applies to C, M, and Y).

In order to enable development from the leading end of the BK latent image, the developing sleeve 14-1 starts rotating before the leading end of the latent image reaches the developing position of the BK developing unit 14, and the BK latent image is moved to the B position.
Developed with K toner. Thereafter, the developing operation of the BK latent image area is continued, but when the rear end of the BK latent image passes the BK developing position, the developing operation is stopped. This is completed at least before the leading end of the C latent image based on the next C image data arrives.

Next, the BK toner image formed on the photosensitive drum 9 is transferred onto the surface of an intermediate transfer belt 19 driven at a constant speed with the photosensitive drum 9 (hereinafter, the intermediate transfer belt is transferred from the photosensitive drum 9 to the intermediate transfer belt). Transfer of the toner image to the belt is referred to as belt transfer).

The belt transfer is performed by applying a predetermined bias voltage to the belt transfer bias roller 20 while the photosensitive drum 9 and the intermediate transfer belt 19 are in contact with each other. The BK, C, M, and Y toner images sequentially formed on the photosensitive drum 9 are sequentially aligned on the same surface of the intermediate transfer belt 19 to form a four-color superimposed belt transfer image. Batch transfer is performed.
The configuration and operation of the intermediate transfer belt unit including the intermediate transfer belt 19 will be described later.

On the photosensitive drum 9 side, the C step is performed after the BK step. At a predetermined timing, reading of C image data by the color scanner 1 starts.
The formation of the C latent image is performed by the laser light writing based on the image data.

In the C developing unit 15, after the rear end of the previous BK latent image has passed the developing position,
Before the leading end of the latent image reaches, the developing sleeve 15-1 starts rotating, and the C latent image is developed with the C toner.

Thereafter, the development of the C latent image area is continued.
When the rear end of the latent image has passed, the development is inactivated as in the case of the BK developing device. This is also completed before the next M latent image front end reaches.

The operations of M and Y are the same as the operations of BK and C described above, since the operations of reading image data, forming a latent image, and developing are the same as those in the above-described processes of BK and C.

Next, the intermediate transfer belt unit will be described. The intermediate transfer belt unit includes an intermediate transfer belt 19.
Are the belt drive roller 21 and the belt transfer bias roller 2
0 and a group of driven rollers, and is driven and controlled by a drive motor (not shown) as described later.

The belt cleaning unit 22 includes a brush roller 22-1, a rubber blade 22-2, a mechanism 22-3 for contacting and separating with the intermediate transfer belt 19, and the like.
After the BK image of the color is transferred to the belt, the second, third, and fourth colors are separated from the surface of the intermediate transfer belt 19 by the contact / separation mechanism 22-3 during the belt transfer.

The paper transfer unit 23 includes a paper transfer bias roller 23-1, a roller cleaning blade 23-2, and a mechanism 23-3 for contacting and separating with the intermediate transfer belt 19. The paper transfer bias roller 23-1 is normally separated from the surface of the intermediate transfer belt 19, but it is timed when the four-color superimposed images formed on the surface of the intermediate transfer belt 19 are collectively transferred to the transfer paper. The paper is biased by the contact / separation mechanism 23-3, and a predetermined bias voltage is applied to the paper transfer bias roller 23-1 to perform transfer to paper.

As shown in FIG. 1, the transfer paper 24 is fed by the paper feed roller 25 and the registration roller 26 at the timing when the leading end of the four-color superimposed image on the surface of the intermediate transfer belt 19 reaches the paper transfer position. Paper is fed.

Here, the way of movement of the intermediate transfer belt 19 is as follows.
The following three types of operation methods can be considered after the belt transfer of the BK toner image of the first color has been completed to the rear end portion. One of these three methods or one of these methods or a copy speed surface or the like depending on the copy size is used. Operated by a combination of efficient schemes.

(1). Constant speed forward system. Even after the belt transfer of the BK toner image, the forward movement is continued at a constant speed. . Then, when the leading end position of the BK image on the surface of the intermediate transfer belt 19 reaches the belt transfer position of the contact portion with the photosensitive drum 9 again, the leading end of the next C toner image is placed on the photosensitive drum 9 side. The image is formed at the right timing so as to be exactly at that position. As a result, the C image is accurately aligned with the BK image, and is belt-transferred onto the intermediate transfer belt 19 surface. . Thereafter, by the same operation, the process proceeds to the M and Y image processes, and a belt transfer image of four-color superposition is obtained. . Following the step of transferring the Y toner image belt for the fourth color, the four-color superimposed toner image on the belt surface is collectively transferred to the transfer paper 24 as described above while moving forward.

(2). Skip forward movement method. When the belt transfer of the BK toner image is completed, the intermediate transfer belt 19 is separated from the surface of the photosensitive drum 9, skips at a high speed in the forward direction, and returns to the original forward speed after moving a predetermined amount. And then again,
The intermediate transfer belt 19 contacts the photosensitive drum 9. . When the front end position of the BK image on the surface of the intermediate transfer belt 19 reaches the transfer position of the intermediate transfer belt again, the front end portion of the next C toner image is positioned exactly on the photosensitive drum 9 side. The image is formed at a proper timing. As a result, the C image is accurately transferred to the BK image, and is belt-transferred. . Thereafter, by the same operation, the process proceeds to the M and Y image processes, and a belt transfer image of four-color superposition is obtained. . Following the belt transfer process for the fourth color Y toner image,
The four-color superimposed toner image on the surface of the intermediate transfer belt 19 is collectively transferred to the transfer paper 24 at the same forward movement speed.

(3). Reciprocating (quick return) method When the belt transfer of the BK toner image is completed, the intermediate transfer belt 19 is separated from the surface of the photosensitive drum 9, and
At the same time as the forward movement is stopped, a high speed return is made in the reverse direction. In the return, the front end position of the BK image on the surface of the intermediate transfer belt 19 passes through a position equivalent to the belt transfer in the reverse direction, and after moving a predetermined distance, stops and enters a standby state. . Next, when the leading end of the C toner image on the photosensitive drum 9 reaches a predetermined position before the belt transfer position, the intermediate transfer belt 19 restarts in the forward movement direction. Further, the intermediate transfer belt 19 comes into contact with the surface of the photosensitive drum 9 again. Also in this case, the C image is transferred onto the surface of the intermediate transfer belt 19 under control so as to accurately overlap the BK image. . Thereafter, by the same operation, the process proceeds to the M and Y image processes, and a belt transfer image of four-color superposition is obtained. . Following the belt transfer process for the fourth color Y toner image,
The toner image moves forward at the same speed without returning, and the four-color superimposed toner image on the surface of the intermediate transfer belt 19 is collectively transferred to the transfer paper 24.

The transfer paper 24 on which the four-color superimposed toner image has been collectively transferred from the surface of the intermediate transfer belt 19 is transported to a fixing unit 28 by a paper transport unit 27, and is fixed to a fixing roller 28-1 controlled to a predetermined temperature. The toner image is fused and fixed with the pressure roller 28-2, and is discharged to the copy tray 29 to obtain a full-color copy.

The photosensitive drum 9 after the belt transfer is
The surface is cleaned by the photoconductor cleaning unit 10, and the charge is uniformly removed by the charge removing lamp 11. The intermediate transfer belt 19 after transferring the toner image onto the transfer paper 24
Means that the belt cleaning unit 22 is
The surface is cleaned by being pressed in 2-3.

At the time of the repeat copy, the operation of the color scanner 1 and the image formation on the photosensitive drum 9 are performed at a predetermined timing following the Y (fourth color) image process of the second sheet BK ( (1st color) Proceed to the image process.

In the intermediate transfer belt 19, following the batch transfer process of the first four-color superimposed image onto transfer paper,
The second BK toner image is transferred to the belt in a region where the surface is cleaned by the belt cleaning unit 22. After that, the operation is the same as that of the first sheet.

The transfer paper cassettes 30 shown in FIG.
Transfer papers of various sizes are stored in 31, 32, and 33, and are fed and conveyed in the direction of the registration roller 26 at a timing from a storage cassette of a transfer paper size designated by an operation panel (not shown). Is done. When manually feeding paper for an overhead projector, thick paper, or the like, a manual paper feed tray 34 is used.

Up to this point, the copy mode for obtaining four full colors has been described.
In the case of the 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, until the predetermined number of sheets is completed, only the developing device of that color is set in the developing operation state, and the intermediate transfer belt 19 is kept in the forward movement direction while being in contact with the surface of the photosensitive drum 9. The copying operation is performed while the belt cleaning unit 22 is driven at the speed and the belt cleaning unit 22 is kept in contact with the intermediate transfer belt 19.

Next, adjustment of the idle rotation of the belt driving roller 21 and the contact pressure of the rubber blade 22-2 will be described.
The rubber blade 22-2 has a function as a cleaning member for removing residual toner on the intermediate transfer belt 19, as shown in FIGS. On the other hand, the elastic blade is in contact with the counter direction.

As shown in FIG. 3, as the number of copies used increases, the coefficient of friction between the rubber blade 22-2 and the intermediate transfer belt 19 sharply increases in the initial stage, and gradually increases thereafter. Initially, as shown in FIG.
Driving force by the belt drive roller 21 to the intermediate transfer belt 19 (the frictional force between the back surface of the belt drive roller 21 and the intermediate transfer belt 19) F _B, frictional force F ₁ between the rubber blade 22-2 and the intermediate transfer belt 19 Therefore, the belt moving speed υ _B of the intermediate transfer belt 19 and the driven roller 35
The peripheral speed upsilon _C equal to the peripheral velocity upsilon _A of the belt drive roller 21.

Here, the frictional force F ₁ is
Assuming that the normal force of the contact portion of −2 is N ₁ and the friction coefficient between the intermediate transfer belt 19 and the rubber blade 22-2 is μ ₁ , F ₁ = μ ₁
It is N _1. However, the coefficient of friction increased since the initial stage (μ ₁
<Μ ₂ ) together with the rubber blade 22-2 and the intermediate transfer belt 1
9 (F ₂ = μ ₂ N ₁ ) increases (F ₁ <F ₂ ),
F ₂ = becomes the F _B belt drive roller 21 will be idle (see Figure 4 (b)). Also, a case where the surface of the back surface or the belt drive roller 21 of the intermediate transfer belt 19 is tainted is likely to idle since the F _B becomes small.

In this embodiment, the idling of the belt driving roller 21 is detected as follows. As shown in FIG. 7, first, the number of rotations of the belt driving roller 21 and the driven roller 35 is detected by well-known detecting means (not shown). Here, when the outer diameter of the belt driving roller 21 is different from that of the driven roller 35, the rotation speed of each roller is converted into the peripheral speed of the roller to detect the idling of the belt driving roller 21. The detection value of the peripheral speed conversion of both compared with the known comparator circuit, the peripheral speed of the driven roller 35 υ _C (= belt moving speed of the intermediate transfer belt 19 upsilon _B) the belt driving roller 21
Of when it is detected that is smaller than the peripheral speed upsilon _A, contact pressure against the belt 19 of the rubber blade 22-2 sends a signal to the blade force adjusting mechanism to be described later from the control circuit (hereinafter, simply " (Referred to as “contact pressure of blade”) is made smaller than the reference value (see FIG. 4C).

The normal blade contact pressure is set relatively high in consideration of the margin so that cleaning can be performed even when there is a large amount of input toner such as untransferred toner of a full-color image. However, if the contact pressure of the blade is too large, the rubber blade 22-2 is entangled and the belt driving roller 21 runs idle even in the initial state without the filming layer. In this embodiment, the hardness is 66 ° and the thickness is 2
mm rubber blade 22-2, the contact angle 22
゜ Under the condition that the protrusion amount is 10 mm, the contact pressure is 20 gf /
cm.

Under these conditions, the contact pressure of the blade is set to 12 gf
When the density is reduced to / cm, cleaning failure occurs for a full-color untransferred image, but sufficient cleaning can be performed for normally input residual toner. Therefore, when the idling of the belt driving roller 21 is detected, if the pressing force is adjusted so that the contact pressure of the blade becomes 12 gf / cm, there is no influence on normal image formation.
Further, in a low-temperature and low-humidity environment, the charge amount of the toner on the intermediate transfer belt 19 increases and the adhesive force increases, and the Young's modulus of the intermediate transfer belt 19 and the rubber blade 22-2 increases, and the intermediate transfer belt 19 Since the adhesiveness of the rubber blade 22-2 is reduced, if the contact pressure of the blade is reduced, there is a risk that cleaning failure may occur even for the transfer residual toner.

Therefore, in this embodiment, as shown in FIG. 4C, a temperature sensor 36 as a temperature detecting means and a humidity detecting means are provided near the upper portion of the contact portion between the rubber blade 22-2 and the intermediate transfer belt 19. A humidity sensor 37 is provided as an example.
In an environment where the relative humidity is 20% RH or less, the contact pressure of the blade can be adjusted in two steps so as to be reduced to 15 gf / cm.

The mechanism for adjusting the blade pressure is shown in FIG.
The displacement amount of the pressure spring 39 is changed using the pressing force adjusting cam 38 as shown in FIG. At this time, as described above, the amount of rotation of the pressing force adjusting cam 38 is controlled based on the detection values of the temperature sensor 36 and the humidity sensor 37 so that the contact pressure of the blade can be adjusted stepwise.

Next, the filming removal operation on the intermediate transfer belt 19 will be described. As shown schematically in FIG. 6, the rubber blade 2 of the belt cleaning unit 22
A filming removal brush 41 having a contact / separation mechanism is disposed downstream of 2-2. However, the installation position of the filming removal brush 41 is not limited to this position. The filming removal brush 41 is used for the intermediate transfer belt 1.
9 has a function as a rubbing member for polishing filming formed on the surface. Reference numeral 40 shown in FIGS. 4 and 5 indicates backup rollers that are respectively disposed to face the rubber blade 22-2 and the filming removal brush 41 via the intermediate transfer belt 19.

In this embodiment, as described above, when the idling of the belt driving roller 21 is detected, a signal of the filming removal operation is sent to the control circuit shown in FIG. Next, filming removal is performed during warm-up after the main switch is turned on. According to the execution command from the control circuit, the brush motor, which is shafted with the filming removal brush 41, rotates, and at the same time, the filming removal brush 4 is rotated by the contact / separation mechanism.
1 contacts the intermediate transfer belt 19. After the completion of the filming removal operation, the contact pressure of the blade is reset to the reference value.

As the structure of the filming removing brush 41, a brush roller made of loop fibers is optimal. By using the loop fiber, the leading end of the loop linearly contacts the surface of the intermediate transfer belt 19, so that the belt surface can be uniformly rubbed.

As a material of the loop fiber, a metal fiber such as stainless steel is excellent in removing ability, but carbon-containing acrylic fiber or the like which is a conductive resin may be used from the viewpoint of cost. In this example, 720 denier / 48 filament, 600 loops / inc made of carbon-containing acrylic fiber
h ² , a brush with a loop hair length of 5 mm was used. Brush outer diameter 18mm, brush rotation speed 179rpm, brush nip width 8mm, belt moving speed 1.5mm / sec
By rotating the intermediate transfer belt 19 two times under the condition of c, the friction coefficient μ = 1.4 between the toner filmed intermediate transfer belt 19 and the rubber blade 22-2 becomes μ = 1.0 after the rubbing operation. Decreased to.

When the intermediate transfer belt 19 is rotated while the rubber blade 22-2 is in contact during the above-described filming removing operation, the rubber blade 22-2 is moved without the toner on the intermediate transfer belt 19. Since the rubber blade 22-2 comes into contact with the rubber blade 22-2 in the counter direction, there is a risk that the rubber blade 22-2 may be caught. Therefore, when performing the filming removing operation, the rubber blade 22-2 is separated from the intermediate transfer belt 19, and only the filming removing brush 41 is brought into contact with and rotated to rotate the intermediate transfer belt 19.

As described above, the installation position of the filming removal brush 41 is not limited to the position shown in FIG. 6, but if it is installed between the rubber blade 22-2 and the belt transfer unit,
The filming removing operation can be performed even when the blade is in contact during the image forming operation. Therefore, there is no need to provide a filming removal mode after a series of copying operations,
It is possible to eliminate a copy operation disable time associated with the filming removal operation.

[0068]

As described above, according to the present invention, the idling of the belt driving roller is detected from the difference in the number of rotations of the belt driving roller and the driven roller, and the pressing force of the cleaning member against the belt-like carrier and the filling are adjusted. Since the feedback is provided to the filming removal mode, a stable image forming operation can be performed even if a filming layer occurs on the surface of the belt-shaped carrier, and the amount of wear of the belt-shaped carrier due to the removal of the filming is minimized. Can be.

According to the second aspect of the present invention, it is possible to prevent the frictional force between the cleaning member and the belt-shaped carrier from increasing or to prevent the belt driving roller from running idle due to dirt on the back surface of the belt-shaped carrier.

According to the third aspect of the present invention, it is possible to set an optimum minimum pressure without being influenced by environmental conditions such as temperature and humidity.

According to the fourth aspect of the invention, the timing of the polishing operation can be minimized.

According to the fifth aspect of the present invention, since the cleaning member is an elastic blade abutting in the counter direction with respect to the rotation direction of the belt-shaped carrier, the cleaning can be performed with one blade without fail. And cost can be reduced.

According to the sixth aspect of the present invention, since the rubbing member is a brush roller made of a metal loop fiber,
The filming layer can be efficiently removed.

According to the seventh aspect of the present invention, since the rubbing member is a brush roller made of conductive resin loop fibers, the cost can be reduced.

According to the eighth aspect of the present invention, the cleaning member can be brought into contact with and separated from the belt-shaped carrier, and when the belt-shaped carrier is polished by the rubbing member,
Since the belt-shaped carrier rotates while the cleaning member is separated from the belt-shaped carrier, the load on the cleaning member can be reduced.

According to the ninth aspect of the present invention, the cleaning member can be brought into contact with and separated from the belt-shaped carrier, and the rubbing member is disposed downstream of the cleaning member in the rotation direction of the belt-shaped carrier. Further, the toner image is arranged on the upstream side of the process section where the toner image is transferred to the belt-shaped carrier, and when the cleaning member is in contact with the belt-shaped carrier, the rubbing member is in contact with the belt-shaped carrier. Since the polishing operation is performed,
The filming layer can be removed even during image formation.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a color copying machine suitable for carrying out the present invention.

FIG. 2 is an enlarged view of a main part around a photosensitive drum and an intermediate transfer belt of the color copying machine according to the present invention.

FIG. 3 is a diagram illustrating a state in which the friction coefficient between the rubber blade and the intermediate transfer belt according to the present invention changes with the number of copies used.

FIG. 4 is a diagram illustrating a relationship between a belt driving roller, a driven roller, a force acting between a rubber blade and an intermediate transfer belt, a frictional force, and a peripheral speed of a main part according to the present invention.

FIG. 5 is a schematic configuration diagram of a pressing force adjusting mechanism for a rubber blade according to the present invention.

FIG. 6 is a schematic configuration diagram of a main part around an intermediate transfer belt unit according to the present invention.

FIG. 7 is a block diagram of a control system according to the application of the present invention.

[Explanation of symbols]

Reference Signs List 19 Intermediate transfer belt (as a belt-like carrier) 20 Belt transfer bias roller 21 Belt drive roller 22-2 Rubber blade (as a cleaning member, elastic blade) 22-3 Contact / separation mechanism 35 Follower roller 36 (Temperature Temperature sensor 37 (as detecting means) Humidity sensor 38 (as humidity detecting means) Pressing force adjusting cam 39 (forming pressing force adjusting means) Pressing spring 40 (forming pressing force adjusting means) Backup roller 41 (sliding) Filming removal brush (as a rubbing member)

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-214882 (JP, A) JP-A-2-191980 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 21/10-21/12 G03G 13/14-13/16 G03G 15/14-15/16 103

Claims (9)

(57) [Claims] 1. A belt-like carrier that is stretched between a belt driving roller and a driven roller, carries a toner image on its surface, and is driven to rotate to convey the toner image.
An image forming apparatus comprising: a cleaning member that removes residual toner on the belt-shaped carrier; and a detachable sliding member that polishes the surface of the belt-shaped carrier. Pressurizing force adjusting means for pressing and changing the pressurizing force, a plurality of rotational speed detecting means for respectively detecting the rotational speeds of the belt driving roller and the driven roller, and a plurality of rotational speeds obtained by the plurality of rotational speed detecting means. And a control means for controlling the operation of the pressing force adjusting means and / or the rubbing member based on an output signal of the comparison circuit. 2. The image forming apparatus according to claim 1, wherein the control means determines that the moving speed of the driven roller outer periphery calculated from the outer diameter and the number of rotations of the driven roller is equal to the outer diameter of the driven roller and the rotation of the driven roller. Image forming wherein the pressing force is reduced below a reference value when the moving speed of the outer periphery of the belt driving roller calculated from the number is smaller than a reference value, and the pressing force is controlled to a reference value when both moving speeds are equal. apparatus. 3. The image forming apparatus according to claim 1, wherein temperature detecting means for detecting a temperature of said belt-shaped carrier and / or said cleaning member, and humidity for detecting humidity near said belt-shaped carrier. An image forming apparatus, comprising: a detection unit, wherein the amount of decrease in the pressing force is changed according to detection results of the temperature detection unit and the humidity detection unit. 4. The image forming apparatus according to claim 1, wherein said control means detects that a moving speed of an outer periphery of said belt driving roller is smaller than a moving speed of an outer periphery of said driven roller. Thereafter, the image forming apparatus controls execution of a polishing operation by the rubbing member. 5. The image forming apparatus according to claim 1, wherein said cleaning member is an elastic blade which abuts in a counter direction with respect to a rotation direction of said belt-shaped carrier. Image forming apparatus. 6. An image forming apparatus according to claim 1, wherein said rubbing member is a brush roller made of a metal loop fiber. 7. An image forming apparatus according to claim 1, wherein said rubbing member is a brush roller made of conductive resin loop fibers. 8. The image forming apparatus according to claim 1, wherein said cleaning member is capable of coming into contact with and separating from said belt-shaped carrier, and said rubbing member is used for said cleaning member. An image forming apparatus, wherein the belt-shaped carrier is rotated while the cleaning member is separated from the belt-shaped carrier during an operation of polishing the belt-shaped carrier. 9. The image forming apparatus according to claim 1, wherein said cleaning member is capable of coming into contact with and separating from said belt-shaped carrier. The rubbing member is disposed downstream of the cleaning member and upstream of a process section where the toner image is transferred to the belt-shaped carrier with respect to the rotation direction of the belt. An image forming apparatus for performing a polishing operation by bringing the rubbing member into contact with the belt-shaped carrier when in contact with the carrier.