JP3071936B2 - 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,
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 between a driving roller and a driven roller, the 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, prevent a decrease in transfer efficiency due to the formation of a filming layer, prevent the blade from being entangled, etc., and secure a long-term stable image formation. 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, wherein the belt-shaped carrier for carrying the toner image by carrying the toner image and being driven to rotate, and a detachable cleaning member for removing residual toner on the carrier. An image forming apparatus having a contactable and slidable rubbing member for polishing the surface of the carrier, a pressing force adjusting means for pressing the cleaning member against the carrier and changing the pressing force, and the carrier. A plurality of detecting means for detecting the presence or absence of the residual toner on a straight line orthogonal to a moving direction of the carrier at a position facing the carrier, and the cleaning member; When the sensor is released from the state of contact with the carrier, all the detection means are the same in order to determine whether or not the streak of the residual toner remaining on the carrier is in a normal state. Determining means for determining whether the same state as the normal state is detected, and control means for controlling the operation of the pressing force adjusting means and / or the rubbing member based on an output signal of the determining means. Configuration.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the control means controls 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 streak of the residual toner remaining on the carrier is not in a linear state. In this case, the pressing force is reduced from a 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 of the third aspect, a temperature detecting means for detecting a temperature of the carrier and / or the cleaning member, and a humidity for detecting a humidity near the carrier. Detecting means for changing the amount of decrease in the pressing force in accordance with the detection results of the temperature detecting means and the humidity detecting means.

According to a fifth aspect of the present invention, in the image forming apparatus according to the second aspect, the rubbing member is located downstream of the cleaning member with respect to the rotation direction of the carrier, and the toner image is It is arranged on the upstream side of the process section transferred to the carrier, and when the cleaning member is in contact with the carrier, the rubbing member is in contact with the carrier to perform a polishing operation. .

According to a sixth aspect of the present invention, in the image forming apparatus of the first aspect, 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, the two elements being arranged symmetrically with respect to a vertical plane perpendicular to the moving direction of the carrier, and projecting the light between the carrier and the detecting means. And a slit-shaped regulating member in the same direction as the arrangement direction of the plurality of detecting means for regulating the reflection range.

[0014]

According to the first aspect of the present invention, the pressure adjusting means for pressing the cleaning member against the carrier and changing the pressure applied thereto, and the carrier for detecting the presence or absence of residual toner on the carrier. A plurality of detecting means arranged at a position facing the body and arranged in a straight line perpendicular to the moving direction of the carrier, and a carrier when the cleaning member is released from the contact state with the carrier; In order to determine whether or not the normal state in which the streaks of the residual toner remaining on the top are linear,
Determining means for determining whether all the detecting means are simultaneously detecting the same state as the normal state; and controlling means for controlling the operation of the pressing force adjusting means and / or the rubbing member based on the output signal of the determining means. Since the cleaning member is provided, it is determined how the cleaning member is in contact with the carrier, and the operation of the pressing force adjusting means and / or the rubbing member is controlled based on the determination result.

According to the second aspect of the invention, in addition to the operation of the first aspect, the start and stop timings of the operation of the rubbing member are optimally controlled.

According to the third aspect of the present invention, in addition to the operation of the second aspect of the present invention, when the judging means judges that the streak of the residual toner remaining on the carrier is not in a straight line, the cleaning member is not used. Of 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 function of the third aspect of the invention, the amount of decrease in the pressure of the cleaning member is changed according to the detection results of the temperature detecting means and the humidity detecting means. .

According to the fifth aspect of the invention, in addition to the operation of the second aspect, the rubbing member is located downstream of the cleaning member with respect to the rotation direction of the carrier and the toner image is carried on the rubbing member. Arranged upstream from the process part to be transferred to the body,
When the cleaning member is in contact with the carrier, the rubbing member is in contact with the carrier to perform the polishing operation, so that filming is also removed during the image forming operation.

According to the sixth aspect of the present invention, in addition to the function of the first aspect, 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. The two elements are arranged plane-symmetrically with respect to a vertical plane perpendicular to the moving direction of the carrier, and between the carrier and the detection means, the projection and reflection ranges of light are set. Since a slit-shaped regulating member is provided in the same direction as the arrangement direction of the plurality of detecting means for regulating, the residual toner remaining on the carrier when the cleaning member is released from the contact state with the carrier. Streaks are reliably detected.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a belt-like carrier of the present invention is used as 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 document is read for each color separation light of, for example, blue (hereinafter, referred to as “B”), green (hereinafter, referred to as “G”), and red (hereinafter, referred to as “R”). And converts it into an electrical 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 strength level of
"BK"), cyan (hereinafter, referred to as "C"), magenta (hereinafter, referred to as "M"), yellow (hereinafter, referred to as "M").
(Referred to as “Y”).

This is converted into a color image by a color image recording apparatus (hereinafter referred to as a “color printer”) 2
Visualization of K, C, M, and Y is performed, and these are superimposed to form a four-color full-color image.

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. 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 referred to as a “BK latent image. 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 disabled. 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 to 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 19). The transfer of the toner image to the belt is called “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 device 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 leading end of the next M latent image arrives.

The operations of M and Y are the same as those of BK and C described above because the respective operations of reading image data, forming a latent image, and developing are the same as those in the above-described steps 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, a mechanism 23-3 for contacting and separating with the intermediate transfer belt 19, and the like. 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. After that, the intermediate transfer belt 19 contacts the photosensitive drum 9 again. . 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 transferred onto the belt in a superimposed manner. . 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 conveyed to a fixing device 28 by a paper conveyance 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 first Y (fourth color) image process. (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 description has been given of the copy mode for obtaining the full color of four colors.
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, the rubber blade 22 at the time of cleaning is used.
A turning-over phenomenon of -2 and a blade turning-up detecting device for detecting the turning-up phenomenon will be described with reference to FIGS. 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.

Intermediate transfer belt 1 of rubber blade 22-2
Regarding the entrainment phenomenon for No. 9, there is a feature that the blade is not involved in the whole at the same time, but starts to turn up from a certain part and is eventually involved. Rubber blade 22-2 is the intermediate transfer belt 1
When released from the state of contact with the surface of No. 9, a streak (hereinafter, referred to as “toner streak”) generated on the intermediate transfer belt 19 due to residual toner or the like blocked by the rubber blade 22-2 was observed. However, if the rubber blade 22-2 is normally in contact with the intermediate transfer belt 19, the toner streak 43-1 appears in a straight line as shown in FIG. , The toner streak 43-2 as shown in FIG.
It has been confirmed that only a certain portion appears as a meandering toner streak. As a matter of course, the image forming timing is controlled so that the toner streaks 43-1 and 43-2 become non-image portions which do not affect the next image formation.

Therefore, attention is paid to the toner streak 43 generated on the intermediate transfer belt 19, and whether or not the toner streak 43 is linear is detected by a detecting device. −
Let 2 determine if there are signs of getting involved.

The blade turning-up detecting device 36 shown in FIGS. 7 and 8 shows a schematic structure thereof. And a light receiving element 36-3 for receiving the reflected light reflected on the surface of the intermediate transfer belt 19, a plurality of detecting elements 36-1 as a detecting means are arranged on a straight line in the longitudinal direction of the rubber blade 22-2. Arranged and mounted. That is, a plurality of the detection elements 36-1 are arranged at a position facing the intermediate transfer belt 19 and on a straight line orthogonal to the moving direction of the intermediate transfer belt 19. A plurality of the elements 36-2 and 36-3 are mounted on a straight line facing the surface, with a plane perpendicular to the moving direction of the intermediate transfer belt 19 as a symmetric plane. In other words, both elements 36-
2, 36-3 are arranged plane-symmetrically with respect to a vertical plane perpendicular to the moving direction of the intermediate transfer belt 19. As shown in FIGS. 8 and 9, between the blade turn-up detecting device 36 and the intermediate transfer belt 19, along the same direction as the blade turn-up detecting device 36, that is, a plurality of detecting elements 36-1 are provided. In the same direction as the arrangement direction, a slit 42 as a regulating member having a slit having a width of 1 to 2 mm for regulating the projection and reflection ranges of light is provided. Since the blade turning-up detecting device 36 and the slit 42 are disposed on the intermediate transfer belt 19 in this manner, it is possible to reliably detect whether or not the toner streak 43 is linear.

That is, if the light beam simultaneously projected from all the light emitting elements 36-2 is received by all the light receiving elements 36-3 as "toner present" by the blade turn-up detecting device 36, the toner line 43-1 is straightened. Is determined to be a state. On the other hand, at least one light receiving element 36-3 is used.
If more than one toner is received as "no toner", it is determined that the toner streak 43-2 is not linear. If the toner streak 43 is not straight, it is determined that there is a sign that the rubber blade 22-2 is involved, and the apparatus enters a mode for preventing the rubber blade 22-2 from being involved as described below.

The rubber blade 22-2 is used for the intermediate transfer belt 1
9 is a major factor involved in the intermediate transfer belt 1
9 has an influence of a filming layer formed on the substrate. When the toner streak is not straight, that is, when 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 effect. Therefore, it is necessary to remove it using, for example, a cleaning brush.

Next, the filming removal operation on the intermediate transfer belt 19 will be described. As shown schematically in FIG. 3, the rubber blade 2 of the belt cleaning unit 22
A filming removal brush 35 having a contact / separation mechanism is provided downstream of 2-2. However, the installation position of the filming removal brush 35 is not limited to this position. The filming removal brush 35 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 41-1 shown in FIGS. 3 and 4 and the like denotes a backup roller arranged to face the rubber blade 22-2 via the intermediate transfer belt 19, and reference numeral 41-2 shown in FIG. Intermediate transfer belt 19
, Backup rollers arranged opposite the filming removal brush 35.

Rubber blade 22-2 and intermediate transfer belt 1
The coefficient of friction with No. 9 sharply increases at the initial stage as the number of copies increases, and gradually increases thereafter. And
If it exceeds a certain value, the rubber blade 22-2 is entangled or the belt driving roller 21 slips.

As described above, when the necessity of the filming removal operation is detected by the blade turn-up detecting device 36, a signal of the filming removal operation is sent to a control circuit (not shown), and after a series of copying operations is completed or after the next copy operation is completed. During the warm-up time after the main switch is turned on, the filming removing operation is performed. An execution command from the control circuit rotates a brush driving motor (not shown) on which the filming removing brush 35 is mounted, and at the same time, causes the filming removing brush 35 to contact the intermediate transfer belt 19 by a well-known contact / separation mechanism. Touched. When a certain time has elapsed, the brush driving motor of the filming removing brush 35 is stopped by an execution command from the control circuit, and at the same time, the filming removing brush 35 is released from the state of contact with the intermediate transfer belt 19 by the contact / separation mechanism. Is done.

When the intermediate transfer belt 19 is rotated with the rubber blade 22-2 abutting during the above-described filming removing operation, the rubber blade 22-2 slides without 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 35 is brought into contact with and rotated to rotate the intermediate transfer belt 19.

As described above, the installation position of the filming removing brush 35 is not limited to the position shown in FIG. 3, but the rubber blade 22-2 and the photosensitive drum 9 to transfer the intermediate transfer belt 1
When the toner image transfer unit 9 is installed between the toner image transfer unit and the belt transfer unit, the rubber blade 22 during the image forming operation is used.
The filming removal operation can be performed even at the time of contact with the −2 intermediate transfer belt 19. Therefore, it is not necessary to provide a filming removal mode after a series of copying operations, and when the filming generation is detected by a surface condition detecting device (not shown), the rubber blade 22-2 is brought into contact with the intermediate transfer belt 19. The filming removal operation is performed in synchronization with the operation. Therefore, it is possible to eliminate the copy operation disable time associated with the filming removal operation.

Next, the detection operation of the blade turn-up detecting device 36 and the adjustment of the contact pressure of the rubber blade 22-2 with 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 involved, the blade turn-up detecting device 36 is turned on.
Is detected, it is determined that the filming removing operation is necessary, and the filming removing operation is executed after a series of copying operations is completed. However, when a large number of copies are taken at one time, there is a danger that the rubber blade 22-2 gets caught or the belt driving roller 21 slips from the time when the rubber blade 22-2 is turned up to the time when the removing operation is performed. There is. In particular, at high temperature and high humidity, the frictional force between the rubber blade 22-2 and the transfer belt 19 increases, so that the risk that the rubber blade 22-2 is caught or the belt driving roller 21 slips increases.
Therefore, at the same time that the turning-up of the rubber blade 22-2 is detected, a signal is sent from the control circuit to a blade pressure adjusting mechanism, which will be described later, so that the contact pressure of the blade becomes smaller than the reference value.

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, when a rubber blade 22-2 having a hardness of 66 ° and a thickness of 2 mm is used, the contact pressure is 20 gf / cm under the conditions of a contact angle of 22 ° and a protrusion amount of 10 mm. Under this condition, the contact pressure of the blade is 12 gf /
cm, cleaning failure occurs for full-color untransferred images, but sufficient cleaning was performed for normally input residual toner. Therefore, when the turning of the rubber blade 22-2 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.
A temperature sensor 37 as a temperature detecting unit and a humidity sensor 38 as a humidity detecting unit are provided near the upper portion of the intermediate transfer belt 19 between the rubber blade 22-2 and the belt driving roller 21. Under an environment of ゜ C or less and a relative humidity of 20% RH or less, the contact pressure of the blade can be adjusted in two stages so as to be reduced to 15 gf / cm.

The rubber blade 22-2 is connected to the intermediate transfer belt 1
As a mechanism for adjusting the blade pressing force as a pressing force adjusting means for pressing the pressure spring 9 and changing the pressing force, a displacement amount of the pressing spring 40 is changed by using a pressing force adjusting cam 39 as shown in FIG. At this time, as described above, the rotation amount of the pressing force adjusting 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 completion of the filming removing operation, the blade contact pressure is reset to the reference value.

Next, the detection operation of the blade turn-up detecting device 36 and input control of a pattern image for predicting and compensating for blade turn-up in advance will be described. As described above, when it is detected by the blade turning-up detecting device 36 that there is a sign that the rubber blade 22-2 is involved, it is determined that the filming removing operation is necessary, and after the series of copying operations is completed, the filming is performed. A removal operation is performed. However, when a large number of copies are made at one time, the rubber blade 22-2 is caught between the detection of the turning-up of the rubber blade 22-2 and the removal operation, or the slip of the belt driving roller 21 shown in FIG. There is a risk of occurrence. In particular, at high temperature and high humidity, the frictional force between the rubber blade 22-2 and the transfer belt 19 increases, so that the risk of occurrence of these problems increases.

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

The most suitable construction of the filming removal brush 35 is a brush roller made of loop fibers. 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 may be used in terms of cost. In this embodiment, a brush made of carbon-containing acrylic fiber and having 720 denier / 48 filaments, 600 loops / inch ² , and a loop length of 5 mm was used. 18m outside diameter of brush
m, brush rotation speed 179 rpm, brush nip width 8 m
m and the 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 is increased after the rubbing operation. Decreased to μ = 1.0.

[0071]

As described above, according to the present invention, it is determined in which state the cleaning member is in contact with the carrier, and based on the result of this determination, the pressing force adjusting means and / or the rubbing member are rubbed. Since the operation of the member is controlled, it is possible to prevent a decrease in transfer efficiency due to the generation of the filming layer and to prevent the cleaning member from being involved, thereby ensuring stable image formation for a long time.

According to the second aspect of the invention, in addition to the effect of the first aspect, the start and stop timings of the operation of the rubbing member are optimally controlled, so that the filming layer can be more reliably formed. It is possible to prevent the transfer efficiency from being lowered and the cleaning member from being involved.

According to the third aspect of the present invention, in addition to the effect of the second aspect of the present invention, when the judging means judges that the streak of the residual toner remaining on the carrier is not linear, the cleaning member Is reduced below the reference value, and the pressure of the cleaning member is controlled to the reference value after the rubbing operation by the rubbing member. Entanglement of the member and slippage of the belt driving roller can be prevented.

According to the fourth aspect of the invention, in addition to the effect of the third aspect of the invention, the amount of decrease in 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, it is possible to set an optimal minimum pressure of the cleaning member regardless of environmental conditions.

According to the fifth aspect of the present invention, in addition to the effect of the second aspect, the rubbing member is located downstream of the cleaning member with respect to the rotation direction of the carrier and the toner image is carried on the rubbing member. Arranged upstream from the process part to be transferred to the body,
When the cleaning member is in contact with the carrier, the rubbing member is in contact with the carrier to perform the polishing operation, so that filming can be removed even during the image forming operation.

According to the sixth aspect of the present invention, in addition to the effect of the first aspect, 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. The two elements are arranged plane-symmetrically with respect to a vertical plane perpendicular to the moving direction of the carrier, and between the carrier and the detection means, the projection and reflection ranges of light are set. Since a slit-shaped regulating member is provided in the same direction as the arrangement direction of the plurality of detecting means for regulating, the residual toner remaining on the carrier when the cleaning member is released from the contact state with the carrier. The streak is reliably detected, so that it is possible to more reliably prevent the transfer efficiency from lowering due to the generation of the filming layer and the cleaning member from being involved.

[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 configuration view of a main part around an intermediate transfer belt as a photosensitive drum and a carrier of the 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 view for explaining toner streaks appearing linearly on the intermediate transfer belt when the rubber blade is normally in contact with the intermediate transfer belt according to the present invention.

FIG. 6 is a diagram illustrating toner streaks that appear to meander only on a part of the intermediate transfer belt when there is a sign that a rubber blade is to be wound around the intermediate transfer belt according to the present invention.

FIG. 7 (a) is a plan view of a blade turning-up detection device according to the present invention, and FIG. 7 (b) is a front view of the detection device.

FIG. 8A is a schematic configuration diagram of a detecting element according to the present invention, and FIG. 8B is an explanatory view of a main part when the detecting element detects a toner streak appearing only in a part on the intermediate transfer belt in a meandering manner. FIG. 7C is an explanatory diagram of a main part when the detection element detects toner streaks appearing in a straight line on the intermediate transfer belt.

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

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

[Explanation of symbols]

19 Intermediate transfer belt (as a belt-like carrier) 20 Belt transfer bias roller 21 Belt drive roller 22 Belt cleaning unit 22-2 Rubber blade (as a cleaning member) 22-3 Contact / separation mechanism 35 (as a rubbing member) ) Filming removal brush 36 Blade turning-up detecting device 36-1 Detecting element 36-2 (as detecting means) 36-2 Light emitting element 36-3 Light receiving element 37 Temperature sensor 38 (as temperature detecting means) 38 Humidity (as humidity detecting means) Sensor 39 (constituting pressing force adjusting means) Pressing force adjusting cam 40 (constituting pressing force adjusting means) Pressing spring 42 (as a regulating member) Slit 43 Toner streak 43-1 Toner streak 43-1 straight line Toner streak 44 pattern image

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 21/00 370-540 G03G 21/14 G03G 21/10-21/12 G03G 15/16-15/16 103

Claims (6)

(57) [Claims] A belt-like carrier for carrying the toner image by carrying the toner image and being driven to rotate, a cleaning member capable of contacting and separating from the carrier for removing residual toner on the carrier, An image forming apparatus comprising: a contactable / separable rubbing member for polishing a surface of a carrier; a pressing force adjusting unit configured to press the cleaning member against the carrier and change a pressing force thereof; A plurality of detecting means for detecting the presence or absence of the residual toner, the detecting means being arranged on a straight line orthogonal to the moving direction of the carrier at a position facing the carrier, and When it is released from the state of contact with the body, all the detection means simultaneously determine the correctness in order to determine whether or not the streak of the residual toner remaining on the carrier is in a normal state. Determining means for determining whether the same state as the normal state is detected; and control means for controlling the operation of the pressing force adjusting means and / or the rubbing member based on an output signal of the determining means. An image forming apparatus comprising: 2. An image forming apparatus according to claim 1, wherein said control means controls start and stop timings of operation of said rubbing member. 3. The image forming apparatus according to claim 2, wherein the control unit determines the pressing force when the determination unit determines that the line of the residual toner remaining on the carrier is not linear. An image forming apparatus, wherein the pressing force is controlled to a reference value after the rubbing operation by the rubbing member is completed, the pressure being reduced below a reference value. 4. The image forming apparatus according to claim 3, further comprising: a temperature detector for detecting a temperature of the carrier and / or the cleaning member; and a humidity detector for detecting humidity near the carrier. An image forming apparatus, wherein the amount of decrease in the pressing force is changed in accordance with the detection results of the temperature detecting means and the humidity detecting means. 5. The image forming apparatus according to claim 2, wherein the rubbing member is located downstream of the cleaning member with respect to a rotation direction of the carrier, and the toner image is transferred to the carrier. Arranged upstream from the process section, when the cleaning member is in contact with the carrier,
An image forming apparatus, wherein a polishing operation is performed by bringing the rubbing member into contact with the carrier. 6. An image forming apparatus according to claim 1, wherein said detecting means comprises a light emitting element for projecting light on a surface of said carrier and a light receiving element for receiving light reflected on the surface of said carrier. , The two elements are arranged plane-symmetrically with respect to a vertical plane orthogonal to the moving direction of the carrier, and regulate the projection and reflection ranges of the light between the carrier and the detection means. An image forming apparatus provided with a slit-shaped regulating member in the same direction as the arrangement direction of the plurality of detecting means.