JPH05119608A - Image forming device for simultaneous developing/ cleaning system - Google Patents

Abstract

PURPOSE:To prevent the inside of a device from being soiled with toner by preventing the toner from remaining. on both end parts of a photosensitive drum. CONSTITUTION:Toner guiding means 21 stuck and disposed on the prescribed parts of both end parts 1a of the upstream side in a rotational direction than the developing roller 6 of the photosensitive drum 1, and guiding residual toner stuck to both end parts concerned 1a, 1a, to the part capable of being used for printing 1b of the photosensitive drum concerned 1, at the time of rotating the photosensitive drum 1, is provided.

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 of a cleaning simultaneous developing system.

[0002]

2. Description of the Related Art FIG. 3 to FIG. 5 show a schematic structure of a conventional image forming apparatus of the simultaneous developing and cleaning type.

In the figure, reference numeral 1 is a photosensitive drum as an image bearing member, which is rotated in the direction of the arrow. The printing use portion 1b between the both ends 1a and 1a of the photosensitive drum 1 has
As shown in, the developing roller 6 of the developing device 3 is in contact. Further, in FIG. 3, 2 is a charger and 8 is a transfer device. The developing device 3 is a contact type one-component non-magnetic developing system using an elastic conductive roller (developing roller) 6 as a developer (toner) carrier, and the one-component toner T stored in the box 4 is used.
0 is converted into charged toner T1 by the charging brush 5 made of silicon rubber or the like, and is supplied to the photosensitive drum 1 side for development. Reference numeral 7 is a replenishing roller for supplying the toner T0 to the developing roller 6.

In the image forming apparatus having such a structure, when printing is performed, the photosensitive drum 1 is rotated in the direction of the arrow, and the peripheral surface of the drum 1 is negatively charged by the charger 2 (charging potential −Vo). ) Will be done. The negatively charged peripheral surface of the photosensitive drum 1 is irradiated with the laser beam L based on the image data. The surface potential of the peripheral surface portion (exposed portion) of the photosensitive drum 1 irradiated with the laser beam L is attenuated to the potential −Vr. The charging potential of the unexposed portion remains -Vo. On the other hand, the developing roller 6 of the developing device 3 is also charged by the charging device 2.
Simultaneously with the charging step by the above, the developing bias potential −Vb is charged.

As shown in FIG. 5C, the charged potential -Vr of the exposed portion has the same polarity as the developing bias potential -Vb, but the absolute value is low (| Vr | <| Vb |). Therefore, the charged toner T1 on the developing roller 6 is attracted as the developing toner T3 to the exposed portion by the electric field action. That is, it is developed [FIG. 5 (C)]. The toner T4 remaining on the developing roller 6 is collected in the developing device 3 and reused.

This developing toner T3 is then transferred to the transfer device 8
Is transferred onto the transfer material P as image toner T5 as shown in FIGS. 3 and 5D.

The toner (T6) remaining on the peripheral surface of the photosensitive drum 1 after transfer is made uniform by the uniformizing brush 9. After that, the surface potential of the peripheral surface of the photosensitive drum 1 is made uniform by the static elimination lamp 11.

Here, the toner (residual toner T6) remaining on the photosensitive drum 1 is charged to the above-mentioned charging potential -Vo by the charger 2 as shown in FIG. 5 (A). By the way, the residual toner T6 adhered to the exposed portion after that is charged to a potential -Vr having an absolute value lower than the developing bias potential -Vb during exposure as shown in FIG. There is no. Rather, it is advantageous because it is effectively used for the development shown in FIG.

On the other hand, the residual toner T6 adhering to the unexposed portion shown in FIG. 5B remains at the charging potential -Vo having the same polarity as the developing bias potential -Vb of the developing roller 6 and a high absolute value. .. Therefore, as shown in FIG. 5C, the residual toner T6 is attracted to the developing roller 6 side by the electric field action. That is, the residual toner T6 attached to the unexposed portion
Are removed from the photosensitive drum 1 and cleaned.

Thus, the photosensitive drum 1 and the developing roller 6
Cleaning is performed at an upstream position where the and are in contact with each other, and subsequently, development is simultaneously performed at the downstream side.

[0011]

By the way, in the above-mentioned image forming apparatus, the residual toner (T6) adhered to the portion of the photosensitive drum 1 (that is, the printing portion 1b) in contact with the developing roller 6 is as described above. It is attracted to the developing roller 6 and cleaned. However, the toner cannot directly adhere to the both ends 1a, 1a of the photoconductor drum 1 which is not in contact with the developing roller 6 from the developing roller 6, but the non-magnetic toner is easily scattered. Of the scattered toner, the oppositely charged toner may adhere to both ends 1a of the photosensitive drum 1.

In this way, both end portions 1 of the photosensitive drum 1 are
When the toner adheres to a and 1a, the toner is not contacted with the developing roller 6 and is not cleaned. Therefore, the printing is repeated and both end portions 1 of the photosensitive drum 1 are
When the amount of adhered toner on a and 1a increases, the toner cannot be completely left on both end portions 1a and 1a and may fall off from the photosensitive drum 1 and stain the inside of the printer.

In view of the above circumstances, an object of the present invention is to form an image by a simultaneous development cleaning system capable of preventing the toner from remaining on both ends of the photosensitive drum and preventing the inside of the apparatus from being contaminated with the toner. To provide a device.

[0014]

SUMMARY OF THE INVENTION According to the present invention, a light-exposed exposed portion and an unexposed portion are formed on a peripheral surface of a photosensitive drum charged by a charger, and printing is performed between both ends of the photosensitive drum. In a developing device having a developing roller in contact with the usable portion, the residual toner adhering to the unexposed portion is removed by utilizing the potential difference between the photosensitive drum side and the developing roller side to which a developing bias is applied. In the image forming apparatus of the simultaneous developing cleaning system in which the toner is adsorbed on the surface of the photosensitive drum to clean the unexposed portion, and at the same time, the toner is supplied from the developing roller side to the exposed portion to develop the image. Toner guide means is provided which is closely arranged at predetermined portions at both ends in the upstream side in the direction, and guides the toner adhering to the both ends to the printing use portion of the photosensitive drum when the photosensitive drum rotates. Characterized in that was.

[0015]

In the present invention, the toner adhering to both ends of the photosensitive drum is guided to the printable portion by the toner guide means when the drum is rotated and is cleaned by the developing roller.

Therefore, it is possible to prevent the toner from remaining on both ends of the photosensitive drum and prevent the inside of the apparatus from being contaminated with the toner.

[0017]

An embodiment of the present invention will be described with reference to the drawings.

As shown in FIGS. 1 and 2, the image forming apparatus of the cleaning and developing simultaneous cleaning type according to the present embodiment includes a drum unit 1U (photosensitive drum 1, charger 2, uniformizing brush 9, static elimination lamp 11, etc.), It comprises a developing device 3, a transfer device 8 and a toner guide means (21) which is a characteristic part of this apparatus.

The same components as those shown in FIGS. 3 and 4 are designated by the same reference numerals, and the description thereof will be omitted or simplified.

Here, the toner guide means is disposed in close contact with predetermined portions of both end portions 1a, 1a of the photosensitive drum 1 on the upstream side in the rotational direction with respect to the contact portion of the developing roller 6, and the both end portions 1a, 1a.
It is a means for guiding the toner attached to 1a to the printable portion 1b of the drum 1 when the photosensitive drum 1 rotates.

In the present embodiment, the toner guide means is composed of a toner guide member 21 having a guide surface 22 inclined from the outer side to the inner side with respect to the rotation direction of the photosensitive drum 1.

The toner guide member 21 is formed of a high-density sponge (or rubber), and is placed at a predetermined portion between the developing roller contact portion of the photosensitive drum 1 and the charging portion of the charger 2. It is arranged so as to be in close contact with the peripheral surface.

As shown in FIG. 1, the toner guide member 21 has an upstream end 22a of the guide surface 22 located outside the end surface of the photosensitive drum 1 and a downstream end 22b.
Are provided so as to be located inside the end surface of the developing roller 6. In particular, in this embodiment, the photosensitive drum 1
The toner guide member 21 has a downstream end 22b of the guide surface 22 corresponding to a portion corresponding to the replenishing roller 7 of the developing roller 6 (shaded lines in FIG. It is configured to enter inside).

Next, the operation will be described.

The toner adhered to both end portions 1a, 1a of the peripheral surface of the photosensitive drum 1 can be used for printing along the guide surface 22 of the toner guide member 21 when the drum 1 is rotated.
Be carried to.

The toner carried to the printable portion 1b of the photosensitive drum 1 is cleaned by the developing roller 6.

According to this embodiment, however, the toner adhering to the both ends of the photosensitive drum 1 is closely attached to the predetermined portions of the both ends 1a, 1a on the upstream side in the rotational direction of the developing roller contact portion. Since the toner guide means (toner guide member 21) for guiding the printable portion 1b of the photosensitive drum 1 when the drum 1 is rotated is provided, the toner remains on both ends 1a, 1a of the photosensitive drum 1. Can be prevented to prevent the inside of the apparatus from being soiled with toner.

Further, the toner guide means is provided on the guide surface 22.
Since it is composed of the toner guide member 21 having the above, it does not become complicated and large.

[0029]

According to the present invention, the toner adhering to both end portions of the photosensitive drum in close contact with predetermined portions on the upstream side of the developing roller contact portion in the rotational direction is attached to the photosensitive drum when the photosensitive drum rotates. Since the toner guide means for guiding the printable portion of the drum is provided, it is possible to prevent the toner from remaining on both ends of the photosensitive drum and prevent the inside of the apparatus from being soiled with the toner.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part of an embodiment of the present invention.

FIG. 2 is a diagram showing an overall configuration of an embodiment.

FIG. 3 is a diagram showing a schematic configuration of a conventional image forming apparatus of a simultaneous development cleaning system.

FIG. 4 is a diagram showing a positional relationship between a photosensitive drum and a developing device of a conventional simultaneous image development cleaning type image forming apparatus.

FIG. 5 is a diagram for explaining a simultaneous charging, exposing, transferring, and developing cleaning process.

[Explanation of symbols]

 1 photoconductor drum 1a, 1a both ends of the photoconductor drum 1b printable portion of the photoconductor drum 3 developing device 6 developing roller 21 toner guide member (toner guide surface)

Claims (1)

[Claims] 1. A developing roller which forms an exposed portion and a non-exposed portion irradiated with light on a peripheral surface of a photosensitive drum charged by a charger and contacts a printable portion between both ends of the photosensitive drum. In the developing device provided with, the residual toner adhering to the unexposed portion is attracted to the developing roller side by utilizing the potential difference between the photosensitive drum side and the developing roller side to which the developing bias is applied, In an image forming apparatus of the simultaneous cleaning type, in which toner is supplied from the developing roller side to the exposing section for development at the same time as cleaning, in a developing simultaneous cleaning type image forming apparatus, a predetermined portion of both end portions in the rotational direction upstream of the developing roller contact portion of the photosensitive drum. And a toner guide means for guiding the toner adhering to both ends of the photosensitive drum to the printing use portion of the photosensitive drum when the photosensitive drum is rotated. The image forming apparatus of the cleaning system when.