JPH07199606A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a defective image by eliminating a defect in electrostatic charging due to a contact electrostatic charging member. CONSTITUTION:The electrostatic charging roller 2 is brought into contact with a photoreceptive drum 1 which is rotated in a direction shown by an arrow R1, and then, the roller 2 is rotated in a direction shown by an arrow R2 following the rotation of the drum 1. An electrostatic charging voltage is impressed on the roller 2 by a power source 2a so as to uniformly and electrostatically charge the surface of the photoreceptive drum 1. Foreign matter such as residual toner, etc., is transferred from the photoreceptive drum 1 to the roller 2. The foreign matter is removed by a brush 10c with fiber flocked on a rotary shaft 10c. The foreign matter is accumulated on the brush 10c when it is used over a long period, then, the cleaning ability of the cleaning member 10 is deteriorated. The foreign matter is knocked down from the brush 10c by intruding the knocking member 11 into the brush 10c. Thus, the deterioration of the cleaning ability of the cleaning member 10 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a laser beam printer, and more particularly, to a charging member for contacting an image carrier to charge it and a charging member for charging the same. The present invention relates to an image forming apparatus provided with a cleaning member for cleaning.

[0002]

2. Description of the Related Art Conventionally, as a primary charging device (a charging device for charging before exposure) such as a copying machine, a device utilizing a discharge phenomenon such as a scorotron charger has been generally used, but recently, it has been used. A so-called contact charging device, that is, a contact charging device, which directly charges a charged surface (surface) of a photosensitive drum by directly contacting a conductive charging member with a photosensitive drum as an image carrier and applying a charging voltage to the charging member, is also available. It's being used.

For example, a charging roller formed of a conductive rubber as a charging member is brought into contact with the surface of the photosensitive drum,
This charging roller is driven to rotate as the photosensitive drum rotates. At this time, the surface of the photosensitive drum is uniformly charged by supplying a charging voltage to a core metal that serves as a shaft of the charging roller.

In this contact charging member, foreign matter such as residual toner on the photosensitive drum is transferred to the surface of the charging roller via the contact portion between the surface of the photosensitive drum and the surface of the charging roller, which contaminates the surface of the charging roller. It tends to be done.
If the surface of the charging roller is contaminated, the surface of the photosensitive drum may be unevenly charged. Therefore, in order to prevent uneven charging, the surface of the charging member may be cleaned by the cleaning member.

As a method of cleaning the charging member, a method of pressing a cleaning pad against the surface of the charging member, a method of rotating a brush of roller-shaped bristles on the surface of the rotating shaft in contact with the surface of the charging member, and the like are devised. ing.

[0006]

However, when the above-mentioned contact charging type charging member is used for a long period of time,
The foreign matter removed from the charging member now accumulates on the cleaning member,
Since the cleaning ability of the cleaning member is deteriorated, it is impossible to sufficiently remove the foreign matter attached to the surface of the charging member, which causes a problem of charging failure.

Further, when the cleaning member is a roller-shaped brush as described above, when the cleaning member is always brought into contact with and rotated by the charging member,
Part of the brush adheres to the charging member, which causes charging failure after long-term use. As countermeasures, it has been proposed to reduce the relative speed between the charging member and the cleaning member, reduce the amount of the cleaning member entering the brush (do not allow the cleaning member to penetrate to the root of the brush), and reduce the brush density. However, depending on the specifications of the image forming apparatus, these measures may be insufficient.

That is, despite having a cleaning member for cleaning the surface of the charging member, the cleaning ability deteriorates due to long-term use, and the foreign matter on the surface of the charging member cannot be sufficiently removed. As a result, poor charging occurs.

Therefore, the present invention, even in long-term use,
An object of the present invention is to provide an image forming apparatus in which the cleaning ability of the cleaning member is prevented from deteriorating and good charging is performed.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and includes an image carrier having a movable charged surface, and the charged surface in contact with the charged surface. A charging member, a cleaning member that contacts the surface of the charging member to clean the surface of the charging member, a driving unit that drives the cleaning member, and a toner image is formed on the charged surface of the image carrier. In an image forming apparatus provided with a toner image forming means and a transfer means for transferring a toner image formed on the surface to be charged to another member, the foreign matter adhering to the cleaning member is contacted with the cleaning member. It is characterized in that it has a hitting member for knocking it down.

In this case, the foreign matter knocked down by the hitting member at the position where the hitting member is arranged falls on the charged surface of the image carrier between the charging member and the toner image forming means. Can be set to a position.

A drive mechanism may be provided to drive an abutting portion of the hitting member that abuts the cleaning member.

Further, an image carrier having a movable charged surface, a charging member for contacting the charged surface to charge the charged surface, and a charging member surface for contacting the charged member surface. A cleaning member for cleaning, a driving means for driving the cleaning member, a toner image forming means for forming a toner image on the charged surface of the image carrier, and a toner image formed on the charged surface for other members. In the image forming apparatus including a transfer unit that transfers the cleaning member to the sheet, the cleaning member is brought into contact with the surface of the charging member and the surface to be charged of the image carrier.

The cleaning means may have a brush with bristles planted on the surface of the rotating shaft, and the brush may be partially arranged on the surface of the rotating shaft.

[0015]

According to the above construction, foreign matter such as toner transferred from the image carrier to the charging member is removed from the charging member by the cleaning member. Further, the cleaning member is struck by the struck member to prevent foreign matters removed from the charging member from accumulating on the cleaning member. Therefore, even when the cleaning member is used for a long period of time, the cleaning ability of the cleaning member does not decrease.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. <Embodiment 1> FIG. 1 is a longitudinal sectional view showing a schematic configuration of an image forming apparatus provided with a cleaning member for cleaning a charging member. The cleaning member shown in the figure has a hitting member.

A photosensitive drum 1 as an image bearing member is arranged at substantially the center of FIG. The photosensitive drum 1 includes a cylindrical conductive substrate 1b made of grounded aluminum or the like, and a photosensitive layer 1a surrounding the surface thereof. The surface of the photosensitive layer 1a is the surface to be charged. The photosensitive drum 1 is rotatably supported by the main body of the apparatus, and is rotationally driven in the direction of arrow R1 by a driving unit (not shown). Around the photosensitive drum 1, a charging roller (charging member) 2 that contacts the surface of the photosensitive drum 1 with a predetermined pressing force and charges the surface of the photosensitive drum 1 uniformly along the rotation direction thereof. Formed on the photosensitive drum 1, an exposure unit 3 that irradiates the surface of the drum 1 with light according to image information to form an electrostatic latent image, a developing device 5 that attaches toner to the electrostatic latent image and develops the toner image. A transfer device 6 that transfers the formed toner image to the transfer material P, a cleaning device 7 that removes toner that remains on the surface of the photosensitive drum 1 without being transferred to the transfer material P, so-called residual toner, and the like are provided.

Further, the transfer device 6 is provided on the downstream side of the photosensitive drum 1 in the conveying direction of the transfer material P (direction of arrow K1).
A conveyor belt 8 that conveys the transfer material P onto which the toner image has been transferred, and a fixing device 9 that fixes the toner image on the transfer material P.
Is provided.

Further, a cleaning member 10 for cleaning the surface of the charging roller 2 is arranged above the charging roller 2. A hitting member 11 is arranged in the vicinity of the cleaning member 10 so as to be in contact therewith. The hitting member 11
The details will be described later.

During image formation, when the start button on the operation panel is pressed, the main motor rotates (all are not shown), and the photosensitive drum 1 connected thereto is rotationally driven in the direction of arrow R1. The charging roller 2 in contact with the surface of the drum 1 is driven to rotate in the direction of arrow 2.

The surface of the photosensitive drum 1 is uniformly charged by the charging voltage applied to the charging roller 2 by the power source 2a. In this embodiment, in order to prevent uneven charging of the photosensitive drum 1, a pre-exposure device (not shown) erases the residual charge on the surface of the photosensitive drum 1, and then the power source 2a supplies -1400V.
Is applied to the charging roller 2 to uniformly charge the surface of the photosensitive drum 1 to -700V.

Next, an electrostatic latent image on the surface of the photosensitive drum 1 is formed. On the surface of the uniformly charged photosensitive drum 1, for example,
Laser light is emitted based on the image information to remove the electric charge in the irradiated portion to form an electrostatic latent image.

This electrostatic latent image is developed by the developing device 5. The developing device 5 carries and conveys the toner contained in the toner container 5b by the developing sleeve 5a, attaches the toner to the electrostatic latent image on the surface of the photosensitive drum 1 and develops the electrostatic latent image to form a toner image.

The toner image on the photosensitive drum 1 is transferred onto the transfer material P by the transfer device 6. The transfer material P is supplied to the photosensitive drum 1 by a conveying device (not shown) in synchronization with the toner image on the photosensitive drum 1.

The transfer material P after the transfer is fixed by the fixing device 9 by the conveyor belt 8 with the unfixed toner image carried on the surface.
Be transported to. In the transfer material P, the toner image is heated and pressed here to be melted and fixed, and fixed on the surface. The transfer material P after fixing is discharged to the outside of the apparatus main body as a final copy.

On the other hand, the residual toner on the photosensitive drum 1 is removed by the cleaning device 7. Cleaning device 7
Has, for example, a cleaning blade (not shown), and scrapes off the residual toner adhering to the surface of the photosensitive drum 1 by rubbing the tip portion thereof against the surface of the photosensitive drum 1.

The photosensitive drum 1 starts to rotate together with the main motor which is activated when the start button is pressed during each of the image forming processes described above, and stops after the entire image forming process is completed. In addition, the cleaning member 1 described above is attached to the main motor.
0 is connected, and the cleaning member 10 cleans the surface of the charging roller 2 while the main motor is rotating.

In the image forming apparatus of this embodiment, the copying speed is 10 sheets / minute, and the photosensitive drum 1, the charging roller 2, the developing device 5, the cleaning device 7, etc. are integrally incorporated in a cartridge container. The process cartridge is configured as a whole. This process cartridge is
It is detachably attached to the main body of the image forming apparatus.
When it reaches the end of its life, the entire process cartridge is replaced with a new one. The life of the process cartridge is set to about 10,000 sheets, and correspondingly, the above-mentioned cleaning member 10 is formed in a spiral shape so that the brush bristle portion ratio is 50%. It should be noted that this flocked portion ratio may be appropriately set according to the specifications of the charging roller 2 or the cleaning member 10.

The cleaning member 10 used in this embodiment is shown in FIG. A gear 10b to which a driving force from a main motor (driving means) is transmitted is provided at one end of the rotary shaft 10a. A brush (contact portion) 10c having a flocked portion ratio of 50% is provided on the outer periphery of the rotating shaft 10a, and the surface of the charging roller 2 is rubbed directly with toner such as toner adhering to the surface of the charging roller 2. Mechanically remove foreign matter.

The cleaning member 10 of this embodiment is the charging roller 2
As the surface is cleaned, the removed foreign substances gradually accumulate on the brush 10c and the like.

The amount of this foreign material increases and the photosensitive drum 1
If it falls to the top, it may cause a defective image. Therefore, in order to prevent the foreign matter from being accumulated on the brush 10c of the cleaning member 10 by inserting the hitting member 11 into the brush 10c of the cleaning member 10,
It is designed to be dropped on the photosensitive drum 1 little by little.

In the present embodiment, as shown in FIG. 1, the disposing position of the hitting member 11 is such that foreign matter dropped from the cleaning member 10 is on the surface of the photosensitive drum 1 between the charging roller 2 and the developing device 5. It is set to drop.

The hitting member 11 may be in the shape of a rod or a flat plate, but if the relative speed of the hitting member 11 to the cleaning member 10 is slow and foreign objects cannot be knocked down sufficiently, it is shown in FIG. As described above, one or a plurality of hitting plates 11b are fixed around the shaft 11a, and the hitting plates 11b are made to enter the brush 10c of the cleaning member 10, and
The shaft 11a may be positively rotated by a drive mechanism (not shown) to increase the relative speed of the striking plate 11b with respect to the brush 10c, thereby increasing the force with which the striking plate 11b strikes the brush 10c. <Embodiment 2> In the embodiment shown in FIG. 4, the cleaning member 10 is brought into contact with both the surface of the charging roller 2 and the surface of the photosensitive drum 1.

In order to remove foreign matters such as toner accumulated on the cleaning member 10, the cleaning member 10 is directly brought into contact with and rotated by the photosensitive drum 1 to obtain the same effect as that of the hitting member.

Part of foreign matter such as toner on the photosensitive drum 1 slips through the cleaning device 7 and is transferred from the surface of the photosensitive drum 1 to the surface of the charging roller 2 and the charging roller 3 is soiled with the foreign matter such as toner. The foreign matter on the surface of the charging roller 2 is swept with the cleaning member 10 and returned to the photosensitive drum 1,
At the same time, foreign matter contained in the cleaning member 10 can be returned to the surface of the photosensitive drum 1 by bringing the cleaning member 10 into contact with the photosensitive drum 1.

The foreign matter such as toner returned on the photosensitive drum 1 is transferred to the transfer material P through the developing device 5 or is removed by the cleaning device 7.

[0037]

As described above, according to the present invention,
For example, foreign matter such as toner transferred from the image carrier to the charging member is removed from the charging member by the cleaning member, and the cleaning member is struck by the hitting member, so that the foreign matter removed from the charging member is collected in the cleaning member. Even if the charging member is used for a long period of time, the cleaning ability of the cleaning member does not deteriorate. Therefore, good charging and further good image formation can be performed for a long period of time.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view illustrating a schematic configuration of an image forming apparatus according to a first exemplary embodiment.

FIG. 2 is a perspective view illustrating a configuration of a cleaning member according to the first exemplary embodiment.

FIG. 3 is a vertical cross-sectional view showing the configuration of another hitting member according to the first embodiment.

FIG. 4 is a vertical cross-sectional view showing the arrangement of the cleaning device according to the second embodiment.

[Explanation of symbols]

 1 image carrier (photosensitive drum) 2 charging member (charging roller) 3 exposure means 5 toner image forming means (developing device) 6 transfer means (transfer device) 7 cleaning device 9 transfer device 10 cleaning member 10a rotating shaft 10c brush 11 tapping Member 11b Strike plate P Transfer material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naomasa Kimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (5)

[Claims] 1. An image carrier having a movable surface to be charged, a charging member for contacting the surface to be charged to charge the surface to be charged, and a surface of the charging member for contacting the surface of the charging member. A cleaning member for cleaning, a drive means for driving the cleaning member,
An image forming apparatus comprising: a toner image forming unit that forms a toner image on the charged surface of the image carrier; and a transfer unit that transfers the toner image formed on the charged surface to another member. An image forming apparatus comprising: a hitting member that abuts on a member and knocks off foreign matter adhering to the cleaning member. 2. The position where the foreign matter knocked down by the hitting member is dropped between the charging member and the toner image forming means on the charged surface of the image bearing member. The image forming apparatus according to claim 1, wherein the image forming apparatus is set to. 3. The image forming apparatus according to claim 1, further comprising a drive mechanism that drives a contact portion of the hitting member that contacts the cleaning member. 4. An image carrier having a movable surface to be charged, a charging member for contacting the surface to be charged to charge the surface to be charged, and a surface of the charging member for contacting the surface of the charging member. A cleaning member for cleaning, a drive means for driving the cleaning member,
An image forming apparatus comprising: a toner image forming unit that forms a toner image on the charged surface of the image carrier; and a transfer unit that transfers the toner image formed on the charged surface to another member. An image forming apparatus, wherein a member is brought into contact with the surface of the charging member and the surface to be charged of the image carrier. 5. The cleaning device according to claim 1, wherein the cleaning means has a brush with bristles planted on the surface of the rotating shaft, and the brush is partially disposed on the surface of the rotating shaft. Or the image forming apparatus described above.