JPH0980999A - Image forming device - Google Patents

Abstract

(57) Abstract: An image forming apparatus capable of preventing a slight amount of toner from flowing out from the edge of a photosensitive member cleaning blade over time and environmental conditions to prevent toner from accumulating on the contact charging means. SOLUTION: The charging member 12 disposed in contact with the electrophotographic photosensitive member 11 and a cleaning blade 16A contacting the photosensitive member 11 are provided, and the photosensitive member 11 moves in the forward direction at the time of image formation, and after the image formation is completed. After rotating in the reverse direction, it rotates in the forward direction and stops. A means for detecting the position of the cleaning blade support, and a means for moving the rotary support shaft when the support reaches a predetermined position, are provided by the detection signal of the detection means according to the settling of the cleaning blade. The contact angle of the cleaning blade with respect to the photosensitive member and the charging unit cleaning conditions are corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer and a facsimile, and more particularly to a contact charging device and an image forming apparatus using the same.

[0002]

2. Description of the Related Art In recent years, a contact charging system has been attracting attention as a charging device for an image forming apparatus using an electrophotographic system. This is because the amount of ozone generated is smaller than that of the conventional corona charger, and the capacity of the power source for obtaining the predetermined charging potential is small, and the cost can be reduced. For this reason, the number of electronic image forming systems adopting the contact charging roller system instead of the corona charging system is increasing.

In this contact charging device, a conductive charging roller is brought into contact with the surface of the photosensitive member, and the roller is 1500 to 200.
Apply a positive or negative DC voltage of about 0 V to the photosensitive surface 8
It is charged to about 00 to 1200V.

However, when this charging device is used in an electronic image forming system, there are the following problems. That is, when toner adheres to the surface of the charging roller, uneven charging occurs, so that the required level for cleaning the photosensitive member becomes extremely high. For example, in the wire charging, which is a conventional non-contact charging method, even if a small amount of toner passes through the cleaning blade, it is scraped off by the developing device, so that it does not appear as a stain on the image after transfer. On the other hand, according to the contact charging method, even if a small amount of toner passes through the blade, the charging roller is in contact with the photosensitive member immediately downstream of the blade, so that the surface of the charging roller is gradually soiled with toner. As a result, an abnormal image may occur as time passes.

There are mainly the following two types of dirt on the charging roller, which has been a problem in the past. One is due to the environmental conditions of assembling the process unit, and is due to the inclusion of foreign matter such as floating dust that occurs when the cleaning blade is brought into contact with the photoconductor. The other is that the toner blocking ability is deteriorated due to environmental changes and temporal factors. In the former, the dust that is sandwiched between the edge of the cleaning blade and the photoconductor does not slip through the edge of the cleaning blade when the photoconductor rotates, so the dust deforms the edge of the cleaning blade and the gap This is a phenomenon in which the toner passes through and the charging roller is soiled with this toner. in this case,
An abnormal image occurs locally. In the latter case, the polyurethane rubber, which is the material of the cleaning blade, becomes worn due to environmental changes and aging factors, the contact area with the photoconductor increases, the surface pressure decreases, and the toner blocking force decreases. This is a phenomenon in which the amount of fine toner remaining on the charging roller increases and the front surface of the charging roller is soiled with the toner. In this case, an abnormal image is generated on the entire surface.

Conventionally, in order to maintain the performance of cleaning the photosensitive member blade over time, in order to prevent paper dust or the like from being caught in the blade edge, as described in JP-A-5-341624, after image formation, It has been proposed to reverse the photoreceptor. Furthermore, although it is undisclosed,
It has also been proposed to regulate the reverse rotation amount of the photoconductor after the image formation. However, these photoconductor reversing mechanisms are disadvantageous because they are not effective countermeasures against the settling of the cleaning blade itself, and the margin cannot be improved with respect to the latter problem described above.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the prior art as described above, and a small amount of toner may be generated from the edge of the photoconductor cleaning blade depending on the initial condition, the elapse of time, and the environmental conditions. (EN) An image forming apparatus capable of preventing the toner from flowing out, thereby preventing the toner from accumulating in the contact charging means, and preventing the charging failure and eventually the image failure caused by the accumulation of the toner in the contact charging means. The purpose is to do.

[0008]

In order to achieve the above object, the inventions of claims 1 and 2 provide an electrophotographic photosensitive member and a charging member and a photosensitive member arranged in contact with the photosensitive member. With the cleaning blade in contact, the photoconductor moves in the positive direction at the time of image formation, rotates in the opposite direction after the completion of image formation, and then rotates in the positive direction to stop, thereby preventing the flattening of the cleaning blade. It is characterized by having been prevented.

The invention according to claims 3 and 4 has an electrophotographic photosensitive member, a charging member disposed in contact with the photosensitive member, and a cleaning blade abutting on the photosensitive member, and a support for the cleaning blade. Has a means for detecting the position of the blade support and a means for moving the rotation support shaft when the support reaches a predetermined position in an image forming apparatus that is rotatable with respect to the photoreceptor support housing. However, the contact angle of the cleaning blade with respect to the photosensitive member and the charging unit cleaning condition are corrected by the detection signal of the above-mentioned detection unit according to the settling of the cleaning blade.

According to the present invention, there are provided an electrophotographic photosensitive member, a charging member arranged in contact with the photosensitive member, and a cleaning blade abutting on the photosensitive member. In an image forming apparatus that is rotatable with respect to a photoconductor support housing, the support of the cleaning blade is provided from the outside of the unit so that the cleaning blade can be brought into contact with and separated from the photoconductor, and Away from
It has a blade edge cleaning member that slides the edge of the cleaning blade facing the photoconductor, and immediately before the cleaning blade contacts the photoconductor, the cleaning member slides on the edge mirror surface side to clean the edge mirror surface side. It is characterized by

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an image forming apparatus according to the present invention will be described below with reference to the drawings. In FIG. 1, the copying machine 10 includes an electrophotographic photosensitive drum 11 which is a latent image carrier. The photosensitive drum 11 is
A photoconductive layer made of an organic material such as OPC is provided on the surface of the photoconductive layer, and the photoconductive layer can rotate in the forward direction (clockwise direction) indicated by the arrow A and the reverse direction.

Around the photosensitive drum 11, a charging roller 12, an exposing device 13, a developing device 14, a transfer device 15, and a cleaning device 16 for executing an image forming process along the forward rotation direction are arranged. There is. When the photoconductor drum 11 rotates in the normal direction, the image forming process including the visible image transfer process by the transfer device 15 of the above-described devices is performed.

Reference numeral 17 in FIG. 1 denotes a pre-transfer exposure lamp.
Reference numeral 8 represents a charge eliminating quenching lamp, and 19 represents an eraser. Further, in the vicinity of the photoconductor drum 11, a paper feeding device 21 including a registration roller 20 for feeding the transfer paper S toward a nip portion between the photoconductor drum 11 and the transfer device 15 is provided. .

The charging roller 12 is a conductive roller capable of rotating by contacting the photoconductive layer of the photosensitive drum 11, and is connected to a high voltage power source 12A to apply a DC voltage or a DC / AC superposed voltage. Thus, the photoconductive layer is uniformly charged.

The charging roller 12 can be brought into contact with and separated from the photosensitive drum 11 by a contacting / separating mechanism (not shown), and is a charging process which is an image forming process centering on the photosensitive drum 11. The surface of the photoconductor drum 11 can be contacted until the exposure process, the development process, and the transfer process are completed, and can be separated from the photoconductor drum 11 after the transfer process is completed. The separation timing may be from the time when the charging process is completed to the time when the next charging process is performed. A cleaning member 12B is arranged above the charging roller 12, and when the charging roller 12 is separated from the photosensitive drum 11, the surface of the rotating charging roller 12 can be cleaned.

The exposure device 13 is for illuminating a document placed on a document table (not shown) such as an illumination light source such as a halogen lamp, and for forming an image of reflected light from the document on the photoconductive layer of the photosensitive drum 11. It has a plurality of mirrors forming an optical path and an image forming lens (not shown), and forms an electrostatic latent image according to an original image on the photoconductive layer. In this embodiment, the negative charge of the photoconductive layer disappears according to the intensity of the reflected light from the original, and the portion where the charge remains is formed as a latent image.

As the developing device 14, for example, a well-known magnetic brush developing device is used, and the magnetic developing material carried and conveyed by the developing sleeve 14A comes into contact with the electrostatic latent image on the photoconductive layer to thereby form an electrostatic latent image. Performs visible image processing of the image.

The pre-transfer exposure lamp 17 is used in order to lower the charging potential of the toner adhering to the electrostatic latent image so as not to lower the transfer efficiency even if there are environmental changes such as temperature and humidity.

The transfer device 15 includes a transfer belt 15A wound around a pair of rollers including a drive roller 15F, a transfer bias roller 15B, a contact / separation mechanism 15C for the transfer belt 15A, and a transfer belt cleaning blade 15D. I have it. In the transfer device 15, the registration roller 20
After setting the registration timing by
The transfer sheet S fed from No. 1 is conveyed while being sandwiched by a nip portion formed between the photoconductive layer surface of the photoconductor drum 11 and the bias voltage from the transfer bias roller 15B via the high-voltage power supply 15B1. Upon application, the visible image carried on the photoconductive layer is transferred to the transfer paper S.

The transfer belt 15A is separated from the photoconductive layer of the photoconductor drum 11 at the time of non-transfer, but at the time of transfer,
The contact / separation mechanism 15C is displaced toward the photoconductor drum 11 by a solenoid 15C2 whose operation is controlled by the control plate 15C1. The excess toner attached to the transfer belt 15A and the impurities such as fibers or paper dust of the transfer paper are removed by the cleaning blade 15D provided in contact with the transfer belt 15A. The electrode plate indicated by reference numeral 15E is provided to stabilize the transferability by making the current flowing from the transfer bias roller 15B to the photoconductor side constant. The transfer paper S on which the visible image on the photoconductive layer is transferred by the transfer device 15 is the transfer belt 1
The sheet is conveyed by 5A, reaches the fixing roller 22, and is discharged to a sheet discharge tray (not shown).

The cleaning blade 15D can be made of polyurethane rubber like the cleaning blade of the photosensitive drum 11. The surface of the transfer belt 15A is coated with fluorine (polyfruco vinylidene), and the friction coefficient μ with respect to the cleaning blade 15D is sufficiently low.

The toner and other foreign matters remaining on the photosensitive drum 11 without being transferred to the transfer paper S are peeled off by the cleaning blade 16A and are conveyed in the conveying pipe 16C by the spiral 16B provided in the conveying pipe 16C. , And is returned to the developing device 14 for reuse. The entire surface of the photoconductor drum 11 is exposed by the charge eliminating lamp 18, and the residual charges in the photoconductive layer of the photoconductor drum 11 are erased to prepare for the next copying.

An outline of an example of a process cartridge applicable to the present invention is shown in FIG. In FIG. 2, the photosensitive drum 11, the cleaning blade 16 </ b> A, and the blade holder 25 are mounted in a cartridge 22 as a photosensitive member support housing, and are removable from the cartridge 22. Further, a bracket 21 that rotatably supports the charging roller 12 is attached to the cartridge 22 with screws and is detachable.
In this embodiment, the photosensitive drum 1 is attached to the cartridge 22.
First, the cleaning blade 16A is assembled, and then the bracket 21 having the charging roller 12 is assembled.

As shown in FIG. 2, the cleaning device 16
Is a cleaning bracket 24 rotatable in a vertical plane about a support shaft 23 provided in the cartridge 22, a support 25 fixed to the cleaning bracket 24 by a screw, and fixed to the support 25 by adhesion or the like. The cleaning blade 16A and the spring 26 for pressing the tip edge portion of the cleaning blade 16A against the surface of the photosensitive drum 11 are provided. One end of the support 25 is bent obliquely downward toward the surface of the photosensitive drum 11, and the cleaning blade 16A is fixed to this bent portion.

The spring 26 urges the bracket 24 and the supporting member 25 integrated with the bracket 24 to rotate counterclockwise in FIG. 2, and the urging force causes the cleaning blade 16 to rotate.
The front edge portion of A is pressed against the surface of the photosensitive drum 11, and the surface of the photosensitive drum 11 is cleaned.
The front end portion 24A of the bracket 24 projects outward from the opening 22C of the cartridge 22.
By pushing up A, the bracket 24 and the supporting body 25 integral therewith are rotated clockwise against the urging force, and the contact of the tip edge portion of the cleaning blade 16A with the photosensitive drum 11 is released.

In this cleaning method, compared to a method in which the cleaning blade is directly fixed to the photosensitive body frame and the edge of the cleaning blade is constantly in contact with the surface of the photosensitive body, the cleaning blade may be changed due to changes in environmental conditions or the passage of time. Although there is an advantage that the change in the contact force with respect to the photoconductor drum 11 is minute, there is a drawback in that the contact angle of the cleaning blade 16A with respect to the photoconductor drum 11 changes due to changes in environmental conditions and the passage of time.
As a result, the optimum condition for scraping off the toner remaining on the surface of the photosensitive drum is broken, and the problem that the charging roller 12 is contaminated by the residual toner is likely to occur.

On the other hand, the above-mentioned cleaning method has an advantage that the contact of the cleaning blade with the photosensitive drum can be released when the image forming apparatus such as a copying machine is shipped.
This is effective in preventing adhesion between the cleaning blade and the photoconductor drum when the apparatus is stored in a high temperature environment for a long time. However, on the other hand, when the blade is brought into contact with the photoconductor again when loaded, foreign matter may be caught between the blade and the photoconductor, which causes the toner remaining on the surface of the photoconductor drum. Passes through the position of the cleaning blade and contaminates the charging roller with toner.

Therefore, in the embodiment of the present invention, in order to prevent foreign matter such as paper dust from being caught between the cleaning blade and the photosensitive member due to factors such as aging, the photosensitive drum is reversed after the image formation. After that, I tried to rotate it further forward. This can also prevent the cleaning blade from settling. Hereinafter, this principle will be described.

In the system in which the bracket 24 is rotatably provided around the shaft 23, and the blade 16A is brought into contact with the photosensitive drum 11 by the rotation of the bracket 24 to perform cleaning, the bracket 24 is at a stationary position and an operating position. When the environment was changed from 30 ° C. and 90% humidity to 10 ° C. and 15% humidity while recording the posture, the results shown in FIG. 3 were obtained. As shown in FIG. 3, the photosensitive drum is rotated in reverse for each job.
Each time, it can be seen that the blade is stationary with the contact angle of the blade with the photosensitive drum becoming smaller. This is because the blade is pulled by the photoconductor drum when the photoconductor drum is rotated in the reverse direction due to the frictional force between the blade and the photoconductor drum.

If the blade is suddenly changed in temperature to a low temperature the next day after being placed in a high temperature environment, the blade settles further and is displaced further from the rest position. The initial setting angle deviated greatly, and the blade setting angle at low temperatures deviated from the initial optimum conditions. This also affects the fact that the contact angle becomes small because the friction coefficient of the blade decreases at low temperatures. As a result, the cleaning ability of the blade deteriorates, and the contamination of the charging roller is accelerated at a low temperature. Therefore, as in the embodiment of the present invention, after image formation,
After the photoconductor drum was rotated in the reverse direction, it was further rotated in the normal direction to solve the above problems.

FIG. 4 shows the timing of the rotating operation of the photosensitive drum. As shown in FIG. 4, t (sec) time after the image formation is stopped, the photosensitive drum reverse rotation signal is set to tg (s).
ec), and after t (sec), a photoconductor drum normal rotation signal is generated for ts (sec).
Letting θg be the rotation angle when the photosensitive drum rotates in the reverse direction and θs be the angle when the photosensitive drum rotates in the normal direction, the relationship of θg> θs, that is, the rotation angle in the reverse direction is larger than the angle in the normal rotation. This is a condition necessary for preventing foreign matters such as paper dust removed from the blade edge by reversing from entering the blade edge again.
Then, as shown in FIG. 5, the contact angle of the blade is once reduced when the photosensitive drum is reversed, but is restored to the operating position by the subsequent forward rotation operation. Therefore, even after the stop, even if the ambient temperature decreases, the change amount is smaller than that in the conventional case where creep is performed from the stopped state after the reverse rotation, and the area where the charging roller is contaminated is not reached. Note that the contact angle of the cleaning blade with respect to the photosensitive drum during operation, reverse forward rotation, and reverse rotation differs depending on environmental conditions because of changes in the friction coefficient.

Next, the embodiment shown in FIGS. 6 to 8 will be described. In the embodiment shown in FIGS. 1 and 2, the cleaning blade is prevented from creep acceleration by the reverse forward rotation operation of the photosensitive drum 11.
In the embodiment shown in, the detection means for detecting the position of the blade support is provided, and the rotation acceleration of the blade support is moved by the detection signal of the detection means to prevent the creep acceleration of the cleaning blade. .

In FIGS. 6 to 8, a filler 24B projects from the tip of the cleaning bracket 24, and a photosensor 27 having a light emitting portion and a light receiving portion sandwiching the movement path of the filler 24B is arranged.
The spindle 23 of the cleaning bracket 24 is the bearing lever 2
The bearing lever 28 is rotatably fitted in the upper portion of the drum 8, and the lower portion of the bearing lever 28 is rotatably supported by a shaft 22E protruding from the drum cartridge 22. The support shaft 23 can move within the range of the elongated hole 22D by penetrating the elongated hole 22D formed in the drum cartridge 22, and the rotation position of the bearing lever 28 can be changed by the support shaft 23. It is possible to switch between a position in which the right end of the long hole 22D abuts and a position in which the long hole 22D abuts the left end. The photo sensor 27 constitutes a detecting means for detecting the height of the filler 24B to detect the position of the cleaning bracket 24 as a blade support during image formation or after image formation is completed.

Above the bearing lever 28, the lever 3 is also provided.
One end of 0 is rotatably fitted. Lever 30
Is urged toward the left side in FIG. 8 by the spring 32 so that the other end contacts the eccentric cam 31 on the main body side. The eccentric cam 31 is rotationally driven by a half-rotation clutch (not shown). Bearing lever 28, lever 3
0, an eccentric cam 31 and the like constitute a moving mechanism of the support shaft 23. The moving mechanism of the support shaft 23 is the cartridge 22.
The front side and the back side have the same structure.

When the filler 24B falls below a predetermined height and the filler 24B is detected by the photosensor 27, it is judged that the contact angle θ of the cleaning blade 16A with the photosensitive drum 11 is below the lower limit of the optimum condition. , The eccentric cam 31 is rotated by half, and the contact position of the other end of the lever 30 with the eccentric cam 31 by the urging force of the spring 32 is set to the eccentric cam 31.
The lever 30 is moved to the left as a small-diameter portion, and thereby the support shaft 23 of the cleaning bracket 24 is moved to the left as indicated by an arrow in FIGS. 6 and 8. At this time, the bearing lever 28 rotates counterclockwise and moves to the second position which is positioned at the left end of the elongated hole 22D of the cartridge 22. The support shaft 23 and the bearing lever 28
The contact angle of the cleaning blade 16A with respect to the photoconductor drum 11 changes to become larger and is corrected within the optimum range due to the movement of, so that the environment in which the creep of the blade 16A is accelerated, for example, from high temperature and high humidity. Even under a condition where the temperature and humidity are suddenly reduced, the deviation of the contact angle of the blade 16A is corrected. Therefore, the deterioration of the blocking ability of the cleaning blade 16A for the toner remaining on the photosensitive drum 11 is suppressed, and the charging roller can be prevented from being soiled. In the above embodiment, the support shaft 2
Although the moving position of 3, that is, the moving position of the blade 16A is two, it may be three or more.

Next, another embodiment of the present invention will be described. In the embodiment shown in FIG. 1, the charging roller 12 is configured to be separated from the photosensitive drum 11 at the time of non-image formation, and when the charging roller 12 is separated from the photosensitive drum 11, a cleaning including a felt or the like is performed. Member 12
The charging roller 12 comes into contact with B with a predetermined contact force, and in this state, the charging roller 12 is rotationally driven by an appropriate driving means and is cleaned by the cleaning member 12B. The cleaning interval is set, for example, to be performed once every 3,000 copies, but in the embodiment shown in FIG. 9, the position of the filler 24B detected by the photo sensor 27 is set to a predetermined value. When it falls below the position, therefore the cleaning blade 1
When the contact angle of 6A falls below a predetermined angle, the subsequent cleaning interval of the charging roller 12, that is, the cleaning interval is switched to once every 1000 sheets. As a result, the charging roller 12
It is possible to prevent the surface of the sheet from being contaminated with the toner, and thus prevent an abnormal image from occurring. In FIG.
“3K” means 3000 sheets, and “1K” means 1000 sheets.

The cleaning time may be switched instead of changing the cleaning interval, and the same effect can be expected. For example, if the cleaning interval is the same,
Assuming that one cleaning time is 30 seconds, when the contact angle of the cleaning blade 16A is below a predetermined angle, the subsequent cleaning time of the charging roller 12 is switched to 60 seconds.

Even if the contact angle θ of the cleaning blade 16A with respect to the photoconductor drum 11 becomes small, the surface pressure on the photoconductor drum 11 decreases, and the passing amount of the residual toner on the surface of the photoconductor drum 11 increases, Since it does not appear as a cleaning failure in the transferred image, it is a problem in actual use that the cleaning interval (interval) of the surface of the charging roller 12 is shortened or the cleaning time is lengthened as described above. It is effective to prevent the above.

Next, another embodiment of the present invention shown in FIG. 10 will be described. In FIG. 10, the blade edge cleaning member 33 has a width of 326 mm and a thickness of 0.05 m, for example.
It consists of mylar (PET) of about m-0.3 mm,
The protrusion amount is 2 mm to 10 mm, and one end edge is the holder 3
4 is fixed. The cleaning member 33 cleans the cleaning blade 16A by slidingly contacting the tip edge of the cleaning blade 16A when the holder 34 rotates counterclockwise in the figure, and improves the slidability with the cleaning blade 16A. The surface is preferably matte to prevent fusing. The rotation center of the holder 34 is the same as the rotation center of the photosensitive drum 11. By doing so, even if the cleaning member 33 moves along with the rotation of the holder 34, the surface of the photoconductor drum 11 is not scratched, and dust and other foreign matter once removed from the cleaning blade 16A are exposed. The foreign matter is not reattached to the body drum 11, and the foreign matter is not sandwiched between the cleaning blade 16A and the photoconductor drum 11.

Normally, the cleaning member 33 is separated from the cleaning blade 16A while the image forming apparatus is stopped and during image formation. Here, the tip end bent portion 24A of the cleaning bracket 24 is pushed upward by applying an external force, and the cleaning bracket 24 is rotated clockwise around the support shaft 23 to separate the cleaning blade 16A from the photosensitive drum 11. And the lever 3 provided integrally with the cleaning bracket 24
5 pushes the protrusion 34A provided on the holder 34 to rotate the holder 34 counterclockwise about the rotation center of the photosensitive drum 11. By this rotation of the holder 34, the free end edge of the cleaning member 33 is brought into sliding contact with the mirror surface of the cleaning blade 16A which is separated from the surface of the photoconductor drum as described above, and scrapes fiber dust or other foreign matter adhered to the mirror surface. Drop it. When the external force applied to the tip bent portion 24A of the cleaning bracket 24 is released and the cleaning bracket 24 is rotated counterclockwise by the urging force, the lever 35 escapes from the protrusion 34A and the holder 34 is urged by the spring 36. By rotating clockwise, the free end edge of the cleaning member 33 separates from the surface of the cleaning blade 16A.

When the diameter of the photosensitive drum 11 is reduced, the holder 34 easily blocks the static elimination light from the static elimination quenching lamp 18, and the static elimination light tends to have a shortage of light quantity. In view of this, in the embodiment shown in FIG. 11, the charge-eliminating quenching lamp 18 is provided on the surface of the cleaning member 33 facing the photosensitive drum 11 via the support 34 that also serves as a reflecting member. In this way, the holder 34
By providing the charge-eliminating quenching lamp 18 integrally with the surface of the photoconductor drum 11, the distance between the surface of the photosensitive drum 11 and the charge-eliminating quenching lamp 18 is kept constant, so that the variation in the light amount is reduced and the cleaning member 33 is further provided. Does not block the optical path of the quenching lamp 18 for static elimination, and the amount of static elimination light does not become insufficient.

In the embodiment shown in FIG. 10, when the image forming apparatus is shipped, the clamp member 37 is attached to the cartridge 22 and the tip bending portion 2 of the cleaning bracket 24.
4A, and the cleaning blade 16A is separated from the photosensitive drum 11. At this time, after the cleaning member 33 slides on the edge mirror surface portion of the cleaning blade 16A, the cleaning blade 16A is in contact with the cleaning member 33, and foreign matter is attached to the cleaning blade 16A and the cleaning blade 16A and the photosensitive drum 11 are attached. It is possible to prevent a foreign substance from being caught between and. When the clamp member 37 is removed after loading, the cleaning member 33, the cleaning blade 16A and the like return to move due to the urging force, and even in this return movement, the cleaning member 33 makes sliding contact with the cleaning blade 16A, so that the cleaning blade 16A has foreign matter removed. After contacting the photosensitive drum 11, the charging roller 12
No local stains occur.

FIG. 12 shows the state of the edge of the cleaning blade 16A when the charging roller 12 is locally contaminated. Even if the dust 50 is floating in the air, it may have a diameter of 50 to 60 μm or more. If a dust of this size is attached to the edge 16G of the cleaning blade 16A, the cleaning blade is generated by the attachment of the dust 50. The toner passes through a slight gap between the surface 16A and the surface of the photoconductor drum 11, and a passing toner mark 51 is generated on the surface of the photoconductor drum 11, which is the charging roller 12.
On the charging roller 12 to stain the charging roller 12. Such a problem occurs in a normal temperature environment, and in the low temperature environment, the toner blade particle size (usually 4 μm to 9 μm) is caused because the rubber material of the cleaning blade 16A is hard.
Even if the above-mentioned smaller dust adheres, the edge of the cleaning blade 16A is deformed, and the residual toner passes through. On the other hand, according to the embodiment as shown in FIG. 10, it is possible to clean the large and small foreign matters adhering to the cleaning blade 16A, so that it is possible to effectively prevent passage of the residual toner on the surface of the photosensitive drum 11. It is possible to prevent the charging roller 12 from being soiled.

[0044]

According to the first and second aspects of the present invention, an image having an electrophotographic photosensitive member, a charging member disposed in contact with the photosensitive member, and a cleaning blade contacting the photosensitive member. In the forming apparatus, the photoconductor moves in the positive direction at the time of image formation, and after the image formation is completed, the photoreceptor rotates in the opposite direction and then rotates in the positive direction to stop, thus reducing the fatigue of the cleaning blade, It is possible to prevent the charging member from being gradually contaminated with residual toner,
It is possible to prevent the occurrence of abnormal images.

According to the third aspect of the present invention, even if the cleaning blade of the photosensitive member is worn out due to environmental conditions or the passage of time, or the contact coefficient with the photosensitive member changes due to a change in the friction coefficient. By moving the support shaft of the cleaning blade support, it is possible to correct the condition for preventing the residual toner on the surface of the photoconductor drum, and the charging member is gradually contaminated with the residual toner with the passage of time, resulting in abnormal images. It can be prevented from occurring.

According to the fourth aspect of the present invention, the cleaning blade of the photoconductor is worn out due to environmental conditions, the passage of time, or the like, or the friction coefficient is changed to prevent the cleaning blade from remaining toner on the surface of the photoconductor. Even if it gradually decreases, the cleaning interval of the charging roller,
Alternatively, by switching the cleaning time, it is possible to prevent the charging member from being gradually contaminated with the residual toner over time, and it is possible to prevent the occurrence of an abnormal image.

According to the fifth and seventh aspects of the present invention, since the edge of the cleaning blade is cleaned by the blade edge cleaning member immediately before the cleaning blade is brought into contact with the photosensitive member, it may float in the air. Even if foreign matter adheres to the cleaning blade across the edge of the cleaning blade, or if foreign matter is mixed in during lubrication for applying to the photoconductor, the foreign matter will not be caught by the blade edge. It is possible to prevent the problem that the abnormal image is locally generated due to the adhesion of the toner to the charging roller without passing the residual toner.

According to the sixth aspect of the present invention, since the blade edge cleaning member for cleaning the edge of the photoconductor cleaning blade rotates about the same rotation center as the photoconductor, the operation of the blade edge cleaning member causes the photoconductor to move. There is no damage and the foreign matter once removed does not adhere to the photoreceptor again.

According to the eighth aspect of the invention, since the photoconductor discharging means is provided integrally with the holder of the blade edge cleaning member for cleaning the edge of the photoconductor cleaning blade, even a photoconductor drum having a small diameter can be used.
It is possible to avoid a problem in which the holder interferes and a shortage of static elimination light occurs.

[Brief description of drawings]

FIG. 1 is a front view schematically showing an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a front view showing a process cartridge unit in the same embodiment.

FIG. 3 is a diagram showing a transition of a contact posture between a photoconductor cleaning blade and a photoconductor drum due to a reversal of the photoconductor and a change in environment at a stationary position and an operating position.

FIG. 4 is a timing chart showing a rotation operation of the photoconductor in the embodiment.

FIG. 5 is a diagram showing the transition of the contact attitude between the photoconductor cleaning blade and the photoconductor drum in the above-described embodiment, showing the stationary position and the operating position while changing the environmental conditions.

FIG. 6 is a front view showing an example of a cleaning blade contact angle correction mechanism applicable to the present invention.

FIG. 7 is an exploded perspective view of the same cleaning blade contact angle correction mechanism as above.

FIG. 8 is a front view showing a drive mechanism portion of the above cleaning blade contact angle correction mechanism.

FIG. 9 is a flowchart showing the operation of the charging roller cleaning mechanism applicable to the present invention.

FIG. 10 is a front view showing an example of a cleaning mechanism of a cleaning blade edge applicable to the present invention.

FIG. 11 is a front view showing a mounting example of a quenching lamp for static elimination applicable to the present invention.

FIG. 12 is a perspective view showing a problem when foreign matter adheres to the cleaning blade.

[Description of Reference Signs] 11 Photoconductor 12 Charging roller 12B Charging roller cleaning means 16A Cleaning blade 22 Photoconductor support housing 23 Rotating support shaft for cleaning blade support 24 Bracket as cleaning blade support 25 Cleaning support 27 Blade support Photo sensor as body position detection means 28 Bearing lever as rotation support shaft movement means 33 Blade edge cleaning member 34 Member rotatable about the same rotation center as the rotation center of the photoconductor

Claims (8)

[Claims] 1. An electrophotographic photosensitive member, a charging member disposed in contact with the photosensitive member, and a cleaning blade abutting on the photosensitive member, wherein the photosensitive member moves in a positive direction during image formation to form an image. After completion, the image forming apparatus rotates in the reverse direction, then rotates in the normal direction and stops. 2. The image forming apparatus according to claim 1, wherein the rotation angle of the photoconductor in the reverse direction is larger than the normal rotation angle immediately before the stop. 3. An electrophotographic photosensitive member, a charging member disposed in contact with the photosensitive member, and a cleaning blade that abuts on the photosensitive member.
In an image forming apparatus which is rotatable with respect to the photosensitive member support housing, means for detecting the position of the blade support member, and means for moving the rotation support shaft of the support member when the support member reaches a predetermined position. An image forming apparatus comprising: 4. An electrophotographic photosensitive member, a charging member arranged in contact with the photosensitive member, a cleaning means for the charging member, and a cleaning blade for contacting the photosensitive member. The cleaning blade support is a photosensitive member support housing. In the image forming apparatus that is rotatable with respect to the contact charging member, the blade has a detection means for detecting the position of the blade support, and when the detection means detects that the support has come to a predetermined position, An image forming apparatus characterized by switching a cleaning interval or a cleaning time for a photoconductor. 5. An electrophotographic photosensitive member, a charging member disposed in contact with the photosensitive member, and a cleaning blade that abuts on the photosensitive member.
In an image forming apparatus that is rotatable with respect to a photoconductor support housing, the cleaning blade support is operated from the outside of the unit so that the cleaning blade can be attached to and detached from the photoconductor, and the cleaning blade can be removed from the photoconductor. An image forming apparatus comprising: a blade edge cleaning member that slides on an edge of a cleaning blade facing a photoconductor when separated. 6. The image forming apparatus according to claim 5, wherein the blade edge cleaning member is attached to a member rotatable about the same rotation center as the rotation center of the photosensitive drum. 7. The image forming apparatus according to claim 6, wherein the blade edge cleaning member cleans the cleaning blade edge in association with the contact / separation operation of the photoconductor and the blade. 8. The image forming apparatus according to claim 6, wherein the holder for the blade edge cleaning member is integrally provided with a photoconductor charge eliminating unit.