JPH05289577A - Image forming device - Google Patents

Abstract

(57) [Summary] [Object] To prevent deterioration of transfer efficiency and entrapment of a cleaning member due to formation of a filming layer in an image forming apparatus, and ensure stable image formation for a long period of time. [Structure] Pressing force adjusting means 39, 40 for pressing the cleaning member 22-2 against the carrier 19 and changing the pressing force.
And a plurality of detection means 36 for detecting the presence / absence of residual toner on the carrier, the detection means 36 being arranged in a straight line in an upward direction perpendicular to the moving direction of the carrier, and when the cleaning member is released from the carrier, In order to determine whether or not the residual toner streaks remaining on the carrier are in a straight line, it is possible to determine whether or not all the detecting means simultaneously detect the same state as the normal state, and 36. And a control means for controlling the operation of the pressing force adjusting means and / or the sliding member 35 based on the output signal of the means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a printer,
More specifically, the present invention relates to an image forming apparatus using an electrophotographic method such as a facsimile, and more specifically, an image forming apparatus having a carrier that carries a toner image and / or transfer paper and conveys the toner image and / or transfer paper to the next step. Regarding

[0002]

2. Description of the Related Art Conventionally, as a device for cleaning adhered toner such as a photoconductor or an intermediate transfer member by the next image forming cycle, a blade cleaning method for pressing the edge of urethane rubber to scrape off the toner, 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,
If a small amount of toner or toner that has melted due to heat or pressure is generated on the photoconductor or intermediate transfer body, it cannot be removed by the blade alone, and the filming layer is gradually formed, resulting in poor transfer performance. The quality is poor.

Particularly in the case of the double transfer method using an intermediate transfer member as an image bearing member, the transfer efficiency is greatly reduced even if a small amount of filming layer is formed. Further, when the filming layer is formed on the image bearing member, the friction coefficient between the blade and the image bearing member increases, so that when the counter blade method is used, the blade is easily caught. Further, when the image carrier is a belt member stretched between a driving roller and a driven roller, the driving roller will idle due to an increase in frictional force between the blade and the image carrier.

Therefore, for example, Japanese Patent Laid-Open No. 21488/1990.
As disclosed in Japanese Unexamined Patent Publication No. 2 (1994), a filming cleaning roller is used as a rubbing member, and the filming layer is removed by rubbing the filming cleaning roller against an image carrier.
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 every several copies.

[0006]

However, in the above technique, there is a problem that when the toner filming layer is removed by the cleaning roller, the image carrier is rubbed too much. Further, in the above-mentioned technique, the generation state of filming changes depending on the usage conditions of the copying machine, etc., so that it cannot be applied to all usage environments.

Therefore, an object of the present invention is to solve the above-mentioned problems, prevent the transfer efficiency from being lowered due to the formation of a filming layer, prevent the blade from being caught in the image forming apparatus, and ensure stable image formation for a long period of time. To provide.

[0008]

In order to achieve the above-mentioned object, the present invention has any one of the following configurations.

According to a first aspect of the present invention, a carrier for carrying a toner image and / or a transfer paper, which is an object to be carried, and being driven to rotate, conveys the object to be carried, and a residue on the carrier. In an image forming apparatus having a contactable / separable cleaning member for removing toner and a contactable / separable rubbing member for polishing the surface of the carrier, the cleaning member is brought into pressure contact with the carrier to change its pressure. The pressing force adjusting means, the detecting means for detecting the presence / absence state of the residual toner on the carrier, a plurality of detecting means arranged in a straight line in an upward direction perpendicular to the moving direction of the carrier, and the cleaning member. In order to determine whether or not the residual toner streaks remaining on the carrier are straight when released from the carrier, all of the detection means are simultaneously in the normal state. Are determination means for determining whether the detected state, the configuration and control means for controlling the operation of said pressure adjusting means and / or said rubbing member on the basis of an output signal of said determining means.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the control means controls the start and stop timings of the operation of the rubbing member.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the control means determines that the determination means is in an abnormal state where the streaks of the residual toner remaining on the carrier are not in a straight line. In this case, the pressing force is reduced below the reference value, and the pressing force is controlled to the reference value after the rubbing operation by the rubbing member is completed.

According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, temperature detecting means for detecting the temperature of the carrier and / or the cleaning member, and humidity for detecting the humidity in the vicinity of the carrier. A detection unit is provided, and the reduction amount of the pressing force is changed according to the detection results of the temperature detection unit and the humidity detection unit.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the control means determines that the streaks of the residual toner remaining on the carrier are not in a straight line. In some cases, a pattern image for reducing the frictional force between the cleaning member and the carrier is input and controlled only in a non-linear portion of the residual toner streaks on the carrier.

According to a sixth aspect of the present invention, in the image forming apparatus according to the second aspect, the cleaning member has the sliding friction member on the downstream side of the cleaning member with respect to the rotation direction of the carrier. As a configuration for performing the polishing operation by abutting the rubbing member on the carrier when the carried object is arranged on the upstream side of the process part that is transferred to the carrier and is in contact with the carrier. There is.

According to a seventh aspect of the present invention, in the image forming apparatus according to the first aspect, the detection means detects a light emitting element that projects light on the surface of the carrier and light reflected by the surface of the carrier. A plurality of light receiving elements for receiving the light receiving elements are arranged on a straight line facing the surface with respect to a plane perpendicular to the moving direction of the carrier as a plane of symmetry. In addition, a slit-shaped restricting member that restricts the projection and reflection range of the light is provided on the symmetrical surface in the same direction as the detection means.

[0016]

According to the first aspect of the present invention, the pressing force adjusting means for pressing the cleaning member against the carrier to change the pressing force, and the moving direction of the carrier for detecting the presence / absence of residual toner on the carrier. With respect to the detection means arranged in a straight line in a vertically upward direction, and when the cleaning member is released from the carrier, it is determined whether or not the streaks of residual toner remaining on the carrier are in a straight line. In order to do so, the determination means determines whether or not all the detection means simultaneously detect the same state as the normal state, and controls the operation of the pressurizing force adjustment means and / or the rubbing member based on the output signal of the determination means. Since the control unit is provided, it is determined in what state the cleaning member is in contact with the carrier, and the operation of the pressing force adjusting unit and / or the rubbing member is controlled based on the determination result. It is.

According to the invention of claim 2, in addition to the operation of the invention of claim 1, the start and stop timings of the operation of the sliding friction member are optimally controlled.

According to the third aspect of the invention, in addition to the effect of the second aspect of the invention, when the determining means determines that the streaks of the residual toner remaining on the carrier are not in a straight line, the cleaning member. The pressure applied to the cleaning member is reduced below the reference value, and the pressure applied to the cleaning member is controlled to the reference value after the rubbing operation by the rubbing member is completed.

According to the fourth aspect of the invention, in addition to the effect of the third aspect of the invention, the reduction amount of the pressing force of the cleaning member is changed according to the detection results of the temperature detecting means and the humidity detecting means. ..

According to the invention of claim 5, in addition to the operation of the invention of claim 1, when the judging means judges that the streaks of the residual toner remaining on the carrier are not in a straight line, Since the pattern image is input and controlled only in the non-straight portion, the frictional force between the cleaning member and the carrier is reduced.

According to the sixth aspect of the present invention, in addition to the function of the second aspect of the invention, the cleaning member has the sliding member on the downstream side of the cleaning member with respect to the rotation direction of the carrier. When the carried object is arranged on the upstream side of the process part where it is transferred to the carrying body and is in contact with the carrying body, the rubbing member comes into contact with the carrying body to perform the polishing operation. Filming is removed even inside.

According to the invention of claim 7, in addition to the operation of the invention of claim 1, the detecting means includes a light emitting element for projecting light on the surface of the carrier and light reflected by the surface of the carrier. And a light receiving element for receiving the light receiving element, both of which are arranged in a line in a direction perpendicular to the moving direction of the carrier.
Since the slit-shaped regulating member for regulating the projection range of the light is provided between the carrier and the detecting unit and in the same direction as the detecting unit, it is on the carrier when the cleaning member is released from the carrier. The streaks of the remaining residual toner can be reliably detected.

[0023]

EXAMPLE An example in which the carrier of the present invention is used as an intermediate transfer belt will be described below with reference to the drawings. First, Fig. 1
According to the schematic construction of a color copying machine suitable for carrying out the present invention,
The configuration around the photosensitive drum and the intermediate transfer belt will be described with reference to FIG.

In FIG. 1, a color image reading device (hereinafter referred to as "color scanner") 1 forms an image of an original 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”). , Convert to electrical image signal.

B, G, R obtained by this color scanner 1
An image processing unit (not shown) performs color conversion processing based on the color separation image signal intensity level of
"BK"), cyan (hereinafter "C"), magenta (hereinafter "M"), yellow (hereinafter "M")
Color image data of "Y") is obtained.

The color image recording apparatus (hereinafter referred to as "color printer") 2 which will be described below
Visualization of K, C, M, and Y is performed, and these are superposed to form a four-color full-color image.

Next, the 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 shown by the arrow, around which a photosensitive member cleaning unit (including a pre-cleaning static eliminator) 10, a static elimination lamp 11, a charger 12, and a potential are provided. 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 has a developing sleeve (14-1, 15-1, 16-1, 17-1) which rotates so that the developer faces the photosensitive drum 9 in order to develop the electrostatic latent image. , A developing paddle (14-2, 15-2, 16-2, 17-2) that rotates to pump up and stir the developer, and a toner concentration detection sensor (14-3, 15-3, 16) of the developer. −
3, 17-3) and the like.

Development operation sequence (color image formation sequence)
Will be described below with the example of BK, C, M and Y. 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 the image data, optical writing by a laser beam and latent image formation are started (hereinafter referred to as BK image). The electrostatic latent image based on the data is called “BK latent image.” C, M, Y
The same about).

In order to enable development from the front end of the BK latent image, the developing sleeve 14-1 starts to rotate before the front end of the latent image reaches the developing position of the BK developing device 14, and the BK latent image becomes B.
Developed with K toner. After that, 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 disabled. This is completed at least before the leading edge of the C latent image by the next C image data arrives.

Next, the BK toner image thus formed on the photoconductor drum 9 is transferred onto the surface of the intermediate transfer belt 19 which is driven at the same speed as the photoconductor drum 9 (hereinafter, the intermediate transfer from the photoconductor drum). The toner image transfer to the belt is called "belt transfer").

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

By the way, on the photosensitive drum 9 side, the C step is performed after the BK step, but the C image data reading by the color scanner 1 is started at a predetermined timing,
A C latent image is formed by writing a laser beam with the image data.

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

After that, the development of the C latent image area is continued,
When the trailing edge of the latent image has passed, the development is inoperative, as in the case of the previous BK developing device. This is also completed before the leading edge of the next M latent image arrives.

In each of the steps M and Y, the respective operations of image data reading, latent image formation, and development are the same as the steps BK and C described above, and therefore the description thereof is omitted.

Next, the intermediate transfer belt unit will be described.

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

The belt cleaning unit 22 comprises a brush roller 22-1, a rubber blade 22-2, a contact / separation mechanism 22-3 for the intermediate transfer belt 19, and the like.
2, 3, 4, after the BK image of the color is transferred to the belt
While the colors are being transferred on the belt, they are separated from the surface of the intermediate transfer belt 19 by the contact / separation mechanism 22-3.

The paper transfer unit 23 comprises a paper transfer bias roller 23-1, a roller cleaning blade 23-2, a belt contact / separation mechanism 23-3 and the like.

The paper transfer bias roller 23-1 is normally separated from the surface of the intermediate transfer belt 19, but when the four-color superposed images formed on the surface of the intermediate transfer belt 19 are collectively transferred to the transfer paper, Timely contact / separation mechanism 23-
The sheet is pressed by 3, and a predetermined bias voltage is applied to the sheet transfer bias roller 23-1, so that the sheet is transferred onto the sheet.

As shown in FIG. 1, the transfer paper 24 is moved by the paper feed roller 25 and the registration roller 26 in accordance with 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. It is fed.

Here, how the intermediate transfer belt 19 moves is as follows.
There are three possible operation methods after the belt transfer of the BK toner image of the first color is completed up to the trailing edge portion. One of these can be used, or in terms of copy speed, etc., depending on the copy size. It is operated by a combination of efficient methods.

(1). Constant speed forward method. After the BK toner image is transferred onto the belt, the forward movement is continued at a constant speed.

.. Then, B on the surface of the intermediate transfer belt 19
When the K image front end position reaches the belt transfer position of the contact portion with the photosensitive drum 9 again, the timing is adjusted so that the front end portion of the next C toner image comes to that position on the photosensitive drum 9 side. And an image is formed. As a result, the C image is accurately aligned with the BK image and the intermediate transfer belt 19
The belt is transferred onto the surface.

.. After that, by the same operation, M, Y
Proceeding to the image process, a belt transfer image of four colors is obtained.

.. Subsequent to the fourth color Y toner image belt transfer process, the four color superimposed toner images on the belt surface are collectively transferred onto the transfer paper 24 as described above while moving forward.

(2). Skip forward 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 is skipped at high speed in the forward direction as it is. After moving a predetermined amount, the initial forward speed is restored. Further, thereafter, the intermediate transfer belt 19 is brought into contact with the photosensitive drum 9 again.

.. Then, B on the surface of the intermediate transfer belt 19
When the front end position of the K image reaches the transfer position of the intermediate transfer belt again, the image is formed on the photosensitive drum 9 side with a timing so that the front end part of the next C toner image comes to that position. ..

As a result, the C image is accurately aligned with the BK image and transferred onto the belt in a superimposed manner.

.. After that, by the same operation, M, Y
Proceeding to the image process, a belt transfer image of four colors is obtained.

.. Subsequent to the belt transfer process of the Y toner image of the fourth color, the intermediate transfer belt 19 is moved at the forward speed as it is.
The four-color superimposed toner image on the surface is collectively transferred to the transfer paper 24.

(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 opposite direction. In the return, the front end position of the BK image on the surface of the intermediate transfer belt 19 passes through the position corresponding to the belt transfer in the opposite direction, and after moving a preset distance, it is stopped and put in a standby state.

.. Next, when the front end portion of the C toner image on the photosensitive drum 9 side reaches a predetermined position before the belt transfer position, the intermediate transfer belt 19 starts again in the forward direction. Further, the intermediate transfer belt 19 is brought into contact with the surface of the photosensitive drum 9 again. In this case as well, the C image is belt-transferred under the condition that it accurately overlaps the BK image on the surface of the intermediate transfer belt 19.

.. After that, by the same operation, M, Y
Proceeding to the image process, a belt transfer image of four colors is obtained.

.. Subsequent to the belt transfer process of the Y toner image of the fourth color, the four-color superimposed toner image on the surface of the intermediate transfer belt 19 is collectively transferred onto the transfer paper 24 without returning and moving forward at the same speed.

The transfer paper 24 to which the four-color superposed toner images are collectively transferred from the surface of the intermediate transfer belt 19 is conveyed to the fixing device 28 by the paper conveying unit 27, and the fixing roller 28-1 controlled to a predetermined temperature. The toner image is fused and fixed by the pressure roller 28-2, and is discharged onto 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 discharged by the charge removing lamp 11. In addition, the intermediate transfer belt 19 after the toner image is transferred onto the transfer paper 24
The belt cleaning unit 22 is again moved to the contact / separation mechanism 2
The surface is cleaned by being pressed by 2-3.

At the time of repeat copying, the operation of the color scanner 1 and the image formation on the photosensitive drum 9 are continued to the Y (fourth color) image process for the first sheet, and then the BK (for the second sheet) at a predetermined timing. (First color) Proceed to the image process.

Further, in the case of the intermediate transfer belt 19, after the batch transfer process of the first four-color superimposed image onto the transfer paper,
The BK toner image of the second sheet is transferred onto the area whose surface is cleaned by the belt cleaning unit 22. After that, the same operation as the first sheet is performed.

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

Up to this point, the description has been made of the copy mode for obtaining the full color of four colors.
In the color copy mode, the same operation as described above is performed for the designated color and the number of times. In the single-color copy mode, only the developing device for that color is kept in the developing operation state until the predetermined number of sheets is completed, and the intermediate transfer belt 19 is kept in contact with the surface of the photosensitive drum 9 and is kept in the forward direction. The copying operation is performed in a state where the belt cleaning unit 22 is driven at a speed and the belt cleaning unit 22 is still in contact with the intermediate transfer belt 19.

Next, the rubber blade 22 at the time of cleaning
A −2 curl phenomenon and a blade curl detection device for detecting the curl phenomenon will be described with reference to FIGS. 5 to 10.

Intermediate transfer belt 1 of rubber blade 22-2
Regarding the entrainment phenomenon with respect to No. 9, the entire blade is not entrained at the same time, but it begins to turn over from a certain part, and the blade is eventually entrained. The rubber blade 22-2 is the intermediate transfer belt 1
9 When the contact state with the surface 9 was released, streaks (hereinafter referred to as “toner streaks”) generated on the intermediate transfer belt 19 due to residual toner blocked by the rubber blade 22-2 were observed. However, if the rubber blade 22-2 is normally in contact with the intermediate transfer belt 19, the toner streaks 43-1 appear in a straight line as shown in FIG. 5, indicating that the rubber blade 22-2 is caught. If it is, the toner streak 43-2 as shown in FIG.
It has been confirmed that only a certain part appears as a meandering toner streak. As a matter of course, the image forming timing of the toner stripes 43-1 and 43-2 is controlled so that the toner stripes 43-1 and 43-2 become a non-image portion that does not affect the next image formation.

Therefore, paying attention to the toner stripes 43 generated on the intermediate transfer belt 19, the detection device detects whether the toner stripes 43 are in a straight line, and the blade turn-up detection device 36 shown in FIG. −
Have them determine if there is a sign that 2 is involved.

The blade turn-up detection device 36 shown in FIGS. 7 to 8 shows a schematic structure thereof, and includes a light emitting element 36-2 for projecting light on the surface of the intermediate transfer belt 19 and a light emitting element 36-2 for projecting light. A detection element 36-1 including a light receiving element 36-3 that receives the reflected light reflected by the surface of the intermediate transfer belt 19 is arranged and attached on the straight line in the longitudinal direction of the rubber blade 22-2. ing. That is, a plurality of light-emitting elements 36-2 and light-receiving elements 36-3 are attached to each other on a straight line facing the surface of the intermediate transfer belt 19 in a direction perpendicular to the rotational movement direction of the intermediate transfer belt 19 as a plane of symmetry. ing. Then, as shown in FIG.
A slit 42 having a width of 1 to 2 mm is provided between the blade turn-up detection device 36 and the intermediate transfer belt 19 in the same direction as the blade turn-up detection device 36. Since the blade turn-up detection device 36 and the slit 42 are arranged on the intermediate transfer belt 19 as described above, it is possible to reliably detect whether or not the above-described toner stripe 43 is in a straight line.

That is, if all the light receiving elements 36-3 simultaneously receive the light projected from all the light emitting elements 36-2 by the blade turn-up detecting device 36, the toner streaks 43-1 will be straight. It is judged that it is a state. On the other hand, at least 1 in the light receiving element 36-3
If more than one receives "no toner", it is determined that the toner stripes 43-2 are not in a straight line. If the toner streak 43 is not in a straight line, it is determined that there is a sign that the rubber blade 22-2 is caught, and the following mode is entered to prevent the rubber blade 22-2 from being caught.

The rubber blade 22-2 is the intermediate transfer belt 1
As a major factor to be caught in 9, the intermediate transfer belt 1
There is an influence of the filming layer formed on the substrate 9. If the toner streaks are not in a straight line, that is, the rubber blade 2
If there is a sign that 2-2 is involved, it is considered that the filming layer formed on the intermediate transfer belt 19 has a very large influence. Therefore, it is necessary to remove this using, for example, a cleaning brush.

Next, the filming removing operation on the intermediate transfer belt 19 will be described.

As shown in the schematic configuration in FIG. 3, a filming removing brush 35 having a contacting / separating mechanism is arranged downstream of the rubber blade 22-2 of the belt cleaning unit 22. However, the installation position of the filming removal brush 35 is not limited to this position. The coefficient of friction between the rubber blade 22-2 and the intermediate transfer belt 19 sharply increases at the initial stage as the number of copies increases, and thereafter gradually increases little by little. Then, when it exceeds a certain value, the rubber blade 22-2 is caught or the belt driving roller 21 slips.

As described above, when the blade flipping detector 36 detects the need for the filming removal operation, a signal for the filming removal operation is sent to the control circuit (not shown), and after a series of copying operations is completed, or The filming removal operation is performed during the warm-up time after the main switch is turned on. In response to an execution command from this control circuit, a brush drive motor (not shown) pivotally mounting the filming removal brush 35 rotates, and at the same time, the filming removal brush 35 contacts the intermediate transfer belt 19 by a well-known contact / separation mechanism. Contacted. Then, after a certain period of time has elapsed, the drive motor of the filming removal brush 35 is stopped by an execution command from the control circuit, and at the same time, the filming removal brush 35 is released from the contact state with the intermediate transfer belt 19 by the contact / separation mechanism. ..

When the intermediate transfer belt 19 rotates while the rubber blade 22-2 is in contact with the film removal operation described above, the rubber blade 22-2 slides without toner on the intermediate transfer belt 19. Since the rubber blade 22-2 is rubbed, there is a risk that the rubber blade 22-2 may be caught when the rubber blade 22-2 is brought into contact with the counter blade in the counter direction. Therefore, when performing the filming removal operation, the rubber blade 22-2 is separated from the intermediate transfer belt 19, and only the filming removal brush 35 is contacted and rotated to rotate the intermediate transfer belt 19.

As described above, the installation position of the filming removal brush 35 is not limited to the position shown in FIG. 3, but the rubber blade 22-2 and the photoconductor drum 9 to the intermediate transfer belt 1 may be installed.
9 is installed between the toner image transfer unit 9 and the toner image transfer unit (hereinafter referred to as “belt transfer”), the filming removal operation is performed even when the rubber blade 22-2 is in contact with the intermediate transfer belt 19 during the image forming operation. It can be performed. Therefore, it is not necessary to provide a filming removal mode after the completion of a series of copying operations, and when the generation of filming is detected by the surface state detection device (not shown), the rubber blade 22
The filming removal operation is performed in synchronization with the contact operation of −2 with respect to the intermediate transfer belt 19. Therefore, it is possible to eliminate the time during which the copy operation cannot be performed due to the filming removal operation.

Next, the detection operation of the blade turn-up detection device 36 and the adjustment of the contact pressure of the rubber blade 22-2 with respect to the intermediate transfer belt 19 (hereinafter referred to as "blade contact pressure") will be described.

As described above, when there is a sign that the rubber blade 22-2 is caught, the blade turn-up detecting device 36
When it is detected by, the filming removal operation is determined to be necessary, and the filming removal operation is executed after the series of copying operations. However, when a large number of copies are scattered at one time, there is a risk that the rubber blade 22-2 may be caught or the belt driving roller 21 may slip during the period from detecting the flipping of the rubber blade 22-2 to performing the removing operation. There is. In particular, when the temperature is high and the humidity is high, the frictional force between the rubber blade 22-2 and the transfer belt 19 increases, so that the risk of being caught by the rubber blade 22-2 and slipping of the belt driving roller 21 increases.
Therefore, at the same time when the turning of the rubber blade 22-2 is detected, a signal is sent from the control circuit to a blade pressing force adjusting mechanism which will be described later so that the contact pressure of the blade becomes smaller than the reference value.

The normal contact pressure of the blade 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 will be rolled up and the belt drive roller 21 will idle even in the initial state without the filming layer.

In this embodiment, when the rubber blade 22-2 having the hardness of 66 ° and the thickness of 2 mm is used, the contact pressure is 20 gf / cm under the condition of the contact angle of 22 ° and the protrusion amount of 10 mm. Under this condition, the contact pressure of the blade is 12 gf /
When it is reduced to cm, a cleaning failure occurs with respect to the full-color untransferred image, but the transfer residual toner that is normally input can be sufficiently cleaned. Therefore, when the curling of the rubber blade 22-2 is detected, if the contact pressure of the blade is adjusted to 12 gf / cm, the normal image formation is not affected. 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, or the Young's modulus of the intermediate transfer belt 19 and the rubber blade 22-2 increases and the intermediate transfer belt 19 and Since the adhesion of the rubber blade 22-2 is lowered, if the contact pressure of the blade is reduced, there is a risk that cleaning failure may occur with respect to the transfer residual toner.

Therefore, in this embodiment, as shown in FIG.
A temperature sensor 37 and a humidity sensor 38 are provided near the upper part of the intermediate transfer belt 19 between the rubber blade 22-2 and the belt driving roller 21. For example, the temperature of the intermediate transfer belt 19 is 20 ° C. or less and the relative humidity is 20% RH or less. Under such environment, the contact pressure of the blade can be adjusted in two steps such as decreasing to 15 gf / cm.

The blade pressure adjusting mechanism is shown in FIG.
The amount of displacement of the pressure spring 40 is changed by using the pressing force adjusting cam 39 as shown in FIG. At this time, as described above, the rotation amount of the pressurizing force adjustment cam 39 is controlled based on the detection values of the temperature sensor 37 and the humidity sensor 38, so that the contact pressure of the blade can be adjusted stepwise. After the filming removal operation is completed, the blade contact pressure is reset to the reference value.

Next, the detection operation of the blade curling detection device 36 and the input control of the pattern image for predicting and compensating the blade curling in advance will be described.

As described above, when there is a sign that the rubber blade 22-2 is caught, the blade turn-up detecting device 36
When it is detected by, the filming removal operation is determined to be necessary, and the filming removal operation is executed after the series of copying operations. However, when a large number of copies are to be made at one time, the rubber blade 22-2 is caught between the flipping detection of the rubber blade 22-2 and the removal operation, and slippage of the belt drive roller 21 shown in FIG. 3 occurs. May occur. Especially when the temperature and humidity are high
Since the frictional force between the rubber blade 22-2 and the transfer belt 19 increases, the risk of causing these problems increases.

Therefore, as shown in FIG. 10, when the blade curling detection device 36 detects curling of the rubber blade 22-2, the detection signal is sent to the control means (not shown), and the control is performed based on this detection signal. The means inputs and controls the rectangular toner pattern image 44 on the intermediate transfer belt 19 only for the portion where the rubber blade 22-2 is turned up. As a result, the frictional force between the portion where the rubber blade 22-2 is turned over and the intermediate transfer belt 19 is reduced, and the rubber blade 22-2 is hard to turn over. Further, since the pattern image 44 is input only to the turned-up portion, the toner can be saved.

As the configuration of the filming removing brush 35, a brush roller made of loop fiber is most suitable. By using the loop fiber, the tip of the loop linearly abuts the surface of the intermediate transfer belt 19, so that the belt surface can be evenly rubbed.

As the material for the loop fiber, metal fiber such as stainless steel is excellent in removing ability, but carbon-containing acrylic fiber or the like may be used from the viewpoint of cost. In this example, a 720 denier / 48 filament made of carbon-containing acrylic fiber, 600 loops / inch ² , and a loop bristle length of 5 mm were used. Brush outline 18m
m, brush rotation speed 179 rpm, brush nip width 8 m
By rotating the belt twice under the conditions of m and a belt moving speed of 1.5 mm / sec, the friction coefficient μ = 1.4 between the toner filmed intermediate transfer belt 19 and the rubber blade 22-2 becomes after the rubbing operation. Has decreased to μ = 1.0.

[0088]

As described above, according to the present invention, it is judged in what state the cleaning member is in contact with the carrier, and based on the result of this judgment, the pressing force adjusting means and / or the rubbing is carried out. Since the operation of the member is controlled, it is possible to prevent the transfer efficiency from being lowered and the cleaning member to be caught due to the formation of the filming layer, and thus it is possible to ensure stable image formation for a long period of time.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, the start and stop timings of the operation of the rubbing member are optimally controlled, so that the filming layer can be more reliably operated. It is possible to prevent the transfer efficiency from being lowered and the cleaning member from being caught up due to the generation.

According to the invention of claim 3, in addition to the effect of the invention of claim 2, when the judging means judges that the streaks of the residual toner remaining on the carrier are not in a straight line, the cleaning member. The pressing force of the cleaning member is controlled to the reference value after the end of the rubbing operation by the rubbing member, so that the transfer efficiency is reduced and the cleaning is more reliably performed due to the formation of the filming layer. It is possible to prevent the winding of the member and the slip of the belt driving roller.

According to the invention of claim 4, in addition to the effect of the invention of claim 3, the decrease amount of the pressing force of the cleaning member is changed according to the detection results of the temperature detecting means and the humidity detecting means. Therefore, the optimum minimum pressure of the cleaning member can be set regardless of the environmental conditions.

According to the invention of claim 5, in addition to the effect of the invention of claim 1, when the judging means judges that the streaks of the residual toner remaining on the carrier are not in a straight line, The pattern image is input-controlled only in the non-straight portion, and the frictional force between the cleaning member and the carrier is reduced, so that the cleaning member can be prevented from being caught.

According to the sixth aspect of the present invention, in addition to the effect of the second aspect of the invention, the cleaning member has the rubbing member on the downstream side of the cleaning member in the rotational direction of the carrier. When the carried object is arranged on the upstream side of the process part where it is transferred to the carrying body and is in contact with the carrying body, the rubbing member comes into contact with the carrying body to perform the polishing operation. Filming can be removed even inside.

According to the invention described in claim 7, in addition to the effect of the invention described in claim 1, the detecting means includes a light emitting element for projecting light on the surface of the carrier and a light reflected on the surface of the carrier. And a light receiving element for receiving the light receiving element, both of which are arranged in a line in a direction perpendicular to the moving direction of the carrier.
Since the slit-shaped regulating member for regulating the projection range of the light is provided between the carrier and the detecting unit and in the same direction as the detecting unit, it is on the carrier when the cleaning member is released from the carrier. The streaks of the remaining residual toner can be reliably detected, and the deterioration of the transfer efficiency and the inclusion of the cleaning member due to the formation of the filming layer can be prevented more reliably.

[Brief description of drawings]

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

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

FIG. 3 is a schematic configuration diagram of main components around a belt cleaning unit according to the present invention.

FIG. 4 is a schematic configuration diagram of a pressing force adjusting mechanism for a rubber blade according to the present invention.

FIG. 5 is a diagram illustrating toner streaks appearing in a straight line on the intermediate transfer belt when a rubber blade normally contacts the intermediate transfer belt according to the present invention.

FIG. 6 is a diagram illustrating toner streaks appearing in a meandering manner only on a part of the intermediate transfer belt when there is a sign that a rubber blade is involved in the intermediate transfer belt according to the present invention.

FIG. 7A is a plan view of a blade turn-up detection device according to the present invention, and FIG. 7B is a front view of the detection device.

FIG. 8A is a schematic configuration diagram of a detection element according to the present invention, and FIG. 8B is an explanatory view of a main part when the detection element detects a toner streak appearing in a meandering part on the intermediate transfer belt. FIGS. 3C and 3C are explanatory views of a main portion when the toner streaks appearing in a straight line on the intermediate transfer belt are detected by the detection element.

FIG. 9 is a plan view of a slit according to the present invention.

FIG. 10 is a diagram illustrating a pattern image that is input only to a toner streak portion that appears in a meandering manner only on a portion on the intermediate transfer belt according to the present invention.

[Explanation of symbols]

19 Intermediate transfer belt (as a carrier) 20 Belt transfer bias roller 21 Belt drive roller 22 Belt cleaning unit 22-2 Rubber blade 22-3 Contact / separation mechanism 35 Filming removal brush (as a rubbing member) 36 Blade turn-up detection Device 36-1 Sensing element 36-2 Light emitting element 36-3 Light receiving element 37 Temperature sensor 38 (as temperature detecting means) Humidity sensor 39 (as humidity detecting means) 39 Pressurizing force adjusting cam 40 (as pressing force adjusting means) Pressure spring (as a pressing force adjusting means) 42 Slit 43 Toner streak 43-1 Linear streak toner 43-2 Non-straight streak 44 Pattern image

Claims (7)

[Claims] 1. A carrier for carrying a toner image and / or a transfer paper as a material to be carried and being driven to rotate, and a contact / separation for removing a residual toner on the carrier. In an image forming apparatus having a cleaning member capable of contacting and separating, and a rubbing member capable of being brought into contact with and separated from the surface of the carrier, a pressing force adjusting unit that presses the cleaning member against the carrier and changes a pressing force thereof. A plurality of detectors arranged in a straight line in an upper direction perpendicular to the moving direction of the carrier for detecting the presence or absence of the residual toner on the carrier, and the cleaning member being released from the carrier. At the same time, in order to determine whether or not the residual toner streaks remaining on the carrier are in a normal state, are all the detection means simultaneously detecting the same state as the normal state? An image forming apparatus comprising: a judgment unit that judges whether or not it is present; and a control unit that controls the operation of the pressing force adjusting unit and / or the rubbing member based on an output signal of the judgment unit. 2. The image forming apparatus according to claim 1, wherein the control unit controls the start and stop timings of the operation of the rubbing member. 3. The image forming apparatus according to claim 2, wherein the control unit controls the applied pressure when the determination unit determines that the residual toner streaks remaining on the carrier are not in a straight line. An image forming apparatus, wherein the pressing force is reduced to a reference value and the pressing force is controlled to a reference value after the rubbing operation by the rubbing member is completed. 4. The image forming apparatus according to claim 3, further comprising temperature detecting means for detecting a temperature of the carrier and / or the cleaning member, and humidity detecting means for detecting a humidity near the carrier. An image forming apparatus, wherein the reduction amount of the pressing force is changed according to the detection results of the temperature detecting unit and the humidity detecting unit. 5. The image forming apparatus according to claim 1, wherein when the determination unit determines that the streaks of the residual toner remaining on the carrier are not in a straight line, the control unit determines that the toner remains on the carrier. 2. An image forming apparatus, wherein a pattern image for reducing a frictional force between the cleaning member and the carrier is input and controlled only in a portion which is not in the straight line. 6. The image forming apparatus according to claim 2, wherein the cleaning member includes the rubbing member downstream of the cleaning member with respect to a rotation direction of the carrier.
Further, when the supported object is arranged on the upstream side of the step portion where it is transferred to the carrier and is in contact with the carrier, the rubbing member is brought into contact with the carrier to perform a polishing operation. An image forming apparatus characterized by the above. 7. The image forming apparatus according to claim 1, wherein the detection unit includes a light emitting element that projects light onto the surface of the carrier and a light receiving element that receives light reflected by the surface of the carrier. , A plurality of them are arranged on a straight line facing the surface in a direction perpendicular to the moving direction of the carrier as a plane of symmetry, and between the carrier and the detection means, and the detection is performed. An image forming apparatus, characterized in that a slit-shaped regulating member for regulating the projection and reflection range of the light is provided on the symmetrical surface in the same direction as the means.