JPH09297514A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the quality of a toner image from being deteriorated and to efficiently recover reattached toner on a photoreceptor to a developing roller side by driving and rotating the developing roller in a forward direction with respect to the rotating direction of the photoreceptor at the time of developing, and driving and rotating it in a counter direction at the time of recovering the reattached toner to the developing roller side. SOLUTION: The developing roller 5 is driven and rotated so that the surfaces of the roller 5 and the photoreceptor 1 may be moved in the same direction at a part where the roller 5 and the photoreceptor 1 are opposed when a developing device 4 develops an electrostatic latent image formed on an image carrier consisting of the photoreceptor 1 to a visible image. The roller 5 is driven and rotated in the forward direction with respect to the rotating direction of the image carrier consisting of the photoreceptor 1 at the time of developing. Since the roller 5 is rotated counterclockwise and the photoreceptor 1 is rotated clockwise in figure, the rotating directions of both of them are reverse to each other. Then, the roller 5 is driven and rotated counter direction with respect to the rotating direction of the photoreceptor 1 at the time of recovering the reattached toner to the roller 5 side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms an electrostatic latent image on a rotationally driven image carrier by means of latent image forming means,
The electrostatic latent image is visualized as a toner image by a developing device, the toner image on the image carrier is transferred to a recording medium by a transfer device, and transfer residual toner on the image carrier after the toner image transfer is removed. The present invention relates to an image forming apparatus that collects by a cleaning member and cleans the surface of the image carrier.

[0002]

2. Description of the Related Art In an image forming apparatus of the above type configured as a copying machine, a printer, a facsimile, or a complex machine thereof, an image carrier is repeatedly used, and therefore, the surface of the image carrier after the toner image is transferred. It is necessary to clean the surface of the image bearing member by removing and collecting the residual toner remaining on the image carrier by a cleaning member. Therefore, conventionally, various cleaning devices for cleaning the image carrier have been proposed and put into practical use, but the conventional cleaning device generally stores the toner collected from the image carrier in a waste toner tank or the like, It is configured to discard this.

By the way, in recent years, in an image forming apparatus of this type which employs an electrophotographic process, it is possible to further reduce the cost and further reduce the amount of toner to be discarded as part of measures against environmental problems. Is requested.

In view of such a point, if the transfer rate of the toner image from the image carrier to the recording medium is set to 100% to eliminate the residual toner after the toner image is transferred, a so-called cleanerless system is adopted. be able to. As a result, not only can the toner to be discarded be eliminated, but also the cleaning device can be omitted, and the image forming system can be simplified and the cost of the image forming device can be reduced. However, at present, it is difficult to make the transfer rate of the toner image 100%, and there is a problem from the viewpoint of reliability.

Therefore, as a second best measure, the transfer residual toner remaining on the surface of the image carrier after the transfer of the toner image is electrostatically adhered to the cleaning member to be temporarily recovered, and then this recovered toner is The toner re-adhered to the surface of the image carrier that does not affect the formation of the electrostatic latent image is electrostatically reattached, and the toner re-adhered to the surface of the image carrier is electrostatically collected by the developing device. Has been proposed (for example, see Japanese Patent Publication No. 61-30274). This eliminates the need for a dedicated means for transferring the collected toner to a waste toner tank or a developing device, thus reducing the cost of the image forming apparatus and reusing the toner. It can be lost.

By the way, in this type of image forming apparatus, in order to visualize the electrostatic latent image formed on the image bearing member, a developer carrying member that carries and conveys the developer while rotating is carried. In addition to using the conveying member, when the re-adhered toner is collected in the developing device, the re-adhered toner is electrostatically collected on the side of the developer carrying member. For the purpose of improving the image quality at the time of development, such a developer carrying / conveying member has been rotated in the forward direction with respect to the rotation direction of the image carrier so that the re-adhered toner is carried on the developer carrying / conveying member side. It was also rotated in the forward direction at the time of recovery. That is, even when the developing device develops the electrostatic latent image into a visible image, and also when the re-adhered toner on the surface of the image carrier is collected to the developer carrier member, the developer carrier member and the image carrier are carried. The rotation direction of the developer carrying / conveying member is set so that the surfaces of the two members move in the same direction at the facing portions of the body.

However, when the developer carrying / conveying member is configured to rotate in the forward direction with respect to the image carrier when the re-adhered toner is collected, the development on the developer carrying / conveying member is performed. The mechanical scraping force that acts on the redeposited toner on the image bearing member, that is, the scavenging force becomes small, and the recovery efficiency of the redeposited toner to the developing device decreases, which causes However, there is a problem in that the toner image of No. 1 has background stains.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to electrostatically collect transfer residual toner on a cleaning member, electrostatically re-adhere the recovered toner to an image carrier, and then re-adhesion. The problem described above in the image forming apparatus of the type in which the accumulated toner is electrostatically collected on the side of the developer carrying and conveying member of the developing device is solved, and the developer carrying and conveying is performed at the time of collecting the reattached toner to the developing device. An image forming apparatus that prevents the developer on the member from reducing the scavenging force applied to the re-adhered toner on the image carrier and efficiently collects the re-adhered toner on the developer carrying and conveying member side. To provide.

[0009]

In order to achieve the above object, the present invention provides an image carrier that is rotationally driven and a latent image forming unit that forms an electrostatic latent image on the carrier while rotating. A developing device, which has a developer carrying and carrying member carrying and carrying a developer, and which visualizes an electrostatic latent image as a toner image by the carried developer, and a toner on the image carrier A transfer device that transfers an image to a recording medium, and a transfer residual toner on the image carrier after the toner image transfer is electrostatically collected temporarily, and then the collected toner is transferred to an electrostatic latent image on the image carrier. An image forming device that includes a cleaning member that reattaches to a surface portion that does not affect image formation, and that electrostatically collects the toner that has reattached to the surface of the image carrier to the developer carrying and conveying member side of the developing device. In the developing device, when the developing device visualizes the electrostatic latent image, the developer is When the re-adhered toner on the surface of the image carrier is collected on the side of the developer carrying member so that the surfaces of the carrier carrying member and the image carrier move in the same direction, the development is performed. An image forming apparatus is proposed in which the rotation direction of the developer carrying / conveying member is set so that the surfaces of the developer carrying / conveying member and the image carrier move in opposite directions.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus according to the present invention. In the figure, a drum-shaped photoconductor 1 which is an example of the structure of an image carrier is rotationally driven in the clockwise direction in the figure by a drive device (not shown), and at this time, a static elimination lamp 13 which is an example of the static eliminator removes static electricity. The surface of the photoconductor 1 is uniformly charged to a predetermined polarity by the action of the charging roller 2 which is an example of a charging device. In this example, the charging roller 2 is connected to the voltage power source E ₁₀ , and uniformly charges the surface of the photoconductor 1 in the negative polarity while rotating in contact with the photoconductor 1. Due to the action of the charging roller 2, the surface of the photoconductor 1 is, for example, -85.
It is charged to 0V. As a charging device for uniformly charging the photoreceptor 1, a charging device disposed apart from the photoreceptor, such as a corona discharger, can be used.

Next, in the exposure unit 3, an exposure scanning device (not shown) performs optical writing scanning with, for example, the light-modulated laser beam 11, so that a predetermined electrostatic latent image is formed on the surface of the photoconductor 1. Is formed. Photoconductor 1
The surface potential of the upper part A irradiated with the laser beam 11, that is, the surface potential of the electrostatic latent image is, for example, about −150 V, and the surface potential of the part B not irradiated with the laser beam 11, that is, the background potential of the background portion of the electrostatic latent image is almost It is maintained at -850V. As described above, in the present embodiment, the exposure scanning device and the charging device including the charging roller 2 form a latent image forming unit that forms an electrostatic latent image on the image carrier including the photoconductor 1. .

The developing device 4 is provided with a developing roller 5 which is an example of a developer carrying / conveying member arranged to face the photoconductor 1, and a pair of stirring paddles 10A and 10B, which are developing containers of the developing device. 9 provided in each container 9
It is rotatably supported by. At the time of development, which will be described later, a voltage of about -600 V, for example, is applied to the developing roller 5 by the voltage power source E ₁ . A voltage having the same polarity as the charging polarity of the photoconductor 1 is applied to the developing roller 5.

A developer, in this example, a two-component developer D having a toner and a magnetic carrier is contained in the developing container 9, and the toner and the carrier are agitating paddles 10A and 10B.
By the rotation of, the particles are triboelectrically charged with opposite polarities. The toner of these is charged to a predetermined polarity, in this example, the same polarity as the charging polarity of the photoconductor 1, that is, a negative polarity.

The developing roller 5 is a portion where the developing roller 5 and the photosensitive member 1 face each other (both of which are) when the developing device 4 develops the electrostatic latent image formed on the image carrier composed of the photosensitive member 1 into a visible image. So that both surfaces move in the same direction.
It is driven to rotate counterclockwise in FIG. In this way, the developing roller 5 is rotationally driven in the forward direction with respect to the rotational direction of the image carrier made of the photoconductor 1 during development. The developing roller 5 rotates counterclockwise in FIG.
Since the photoconductor 1 rotates in the clockwise direction, the rotation directions themselves are opposite to each other.

The developer in which the toner and the carrier are charged as described above is magnetically carried on the peripheral surface of the developing roller 5 by the action of the magnetic force of a magnet (not shown) provided in the developing roller 5. And is conveyed in the rotation direction of the developing roller 5. That is, the developer is conveyed in the forward direction with respect to the rotation direction of the photoconductor 1. Developing roller 5
The developer regulating member 18 is disposed opposite to the above. In the present example, the developer regulating member 18 is arranged on the upper side of the developing roller 5 in the drawing, and the developer regulating member 18 is provided with a hook-shaped protrusion 18a facing the developing roller 5 with a predetermined gap. The developer carried on the developing roller 5 is scraped by the protrusion 18a.

The developer on the developing roller 5 whose conveyance amount is regulated by the developer regulating member 18 is conveyed toward the developing section 6 where the roller 5 and the photoconductor 1 face each other, and in the developing section 6. The toner in the developer is electrostatically attracted to the electrostatic latent image on the photoconductor 1 and adheres to that portion. That is, the toner charged to the negative polarity, which is the same as the charging polarity of the photoconductor, electrostatically adheres to the surface portion A of the photoconductor exposed to the laser beam, and the electrostatic latent image is visualized as a toner image. It is. Such a developing method is called a reversal developing method (negative / positive developing method).

At the time of this development, the developing roller 5 rotates in the forward direction with respect to the rotation direction of the photoconductor 1 as described above. The rotation direction of the developing roller 5 is set so that the surfaces of the developing roller 5 and the photosensitive member 1 face each other in the same direction, that is, at the closest portion between the developing roller 5 and the photosensitive member 1, and the developing roller 5 carries the developing roller. The agent is conveyed in the rotation direction of the developing roller 5. As a result, the image quality of the toner image formed on the photoconductor 1 can be improved.

A transfer roller 7, which is an example of a transfer device, is disposed below the photoconductor 1. The transfer roller 7 rotates in the forward direction with respect to the rotation direction of the photoconductor 1, and toward the transfer portion 8 between the transfer roller 7 and the photoconductor 1 facing the transfer roller 7, a recording medium made of a transfer paper 16 is formed. Are transferred in the direction of the arrow P, and the transfer roller 7 is pressed against the surface of the photoconductor 1 via the transfer paper 16 sent to the transfer unit 8, and at this time, the function of the transfer roller 7 causes the photoconductor to move. The toner image formed on the transfer sheet 1 is transferred onto the transfer paper 16.

That is, the transfer roller 7 is powered by the power source E _3.
Is applied with a positive polarity voltage opposite to the charging polarity of the toner on the photoconductor 1, for example, a voltage of +950 V, and at this time, a negative polarity toner T forming a toner image on the photoconductor 1.
Are electrostatically attracted to the transfer paper 16 side and adhere to the transfer paper. It is also possible to use a transfer device separated from the photoconductor 1 such as a transfer device including a corona discharger.

The transfer paper 16 on which the toner image has been transferred is separated from the photoconductor 1 by a separating device (not shown) and is sent to a fixing device (not shown).
The toner image on 6 is fixed. In this way, the transfer paper 16 is ejected outside the image forming apparatus main body as copy paper.

As described above, the image forming apparatus of this embodiment has the image carrier composed of the photosensitive member 1 which is rotationally driven, the latent image forming means for forming an electrostatic latent image on the image carrier, and the latent image forming means. The developing device 4 visualizes the electrostatic latent image as a toner image, and the transfer device 7 includes a transfer roller 7 for transferring the toner image on the image carrier to a recording medium composed of the transfer paper 16. The cleaning member includes a cleaning roller 12 and a charge removing device including the charge removing lamp 13 described below. The developing device 4 has a developer carrying and conveying member composed of a developing roller 5 for carrying and carrying the developer while rotating, and the electrostatic latent image is visualized as a toner image by the carried developer. To do. The charging device, the exposure unit 3 for the image carrier by the latent image forming means, the developing device 4, the transfer device, the cleaning member, and the charge eliminating device are arranged in this order along the rotation direction of the image carrier.

The toner image on the photoconductor 1 is transferred to the transfer paper 16 at the transfer portion 8. After the toner image is transferred, the photoconductor 1 is transferred.
The toner remaining on the photoconductor 1 without being transferred to the transfer paper 16 adheres to the surface of the. Transfer residual toner T ₁
When it reaches the cleaning unit 14, it is electrostatically and temporarily collected on the surface of a cleaning roller 12 which is an example of a cleaning member.

The cleaning roller 12 has a core member 12a made of a rigid body and a conductive or medium-resistance elastic body 12b fixed to the surface of the core member 12a. In the illustrated example, the core member 12a. Is made of a round shaft-shaped conductive metal, and the elastic body 12b is made of a foamed body formed in a cylindrical shape concentric with the core member 12a. The cleaning roller 12 is housed in the cleaning case 17 shown in FIG. 1, and each end of the core member 12a is rotatably supported by the front and rear side walls 17a of the cleaning case 17. The cleaning roller 12, together with the developing roller 5, the charging roller 2, and the transfer roller 7, is positioned substantially parallel to the photoconductor 1.

Here, in FIG. 1, most of the toner T of the toner image directed from the developing section 6 to the transfer section 8 is toner having a charging polarity at the time of development, that is, a negative polarity toner in this example. On the other hand, when the toner image is transferred, a voltage having a polarity opposite to the toner charging polarity at the time of development, which is a positive polarity in this example, is applied to the transfer roller 7, so that the toner remains on the photoconductor 1 after the toner image is transferred. The adhered toner, that is, the transfer residual toner T ₁ is a toner in which positive and negative toners are mixed. The transfer residual toner is transferred to the cleaning unit 14 in a state in which both positive and negative polarity toners are mixed.

The cleaning roller 12 is rotationally driven in an appropriate direction by a driving device (not shown) when the transfer residual toner T 1 on the photoconductor ₁ is collected. In the illustrated example, the cleaning roller 12 is in the clockwise direction in FIG. 1 (the direction of arrow a), that is, in the contact portion with the photoconductor 1, the direction opposite to the rotation direction of the photoconductor 1 (counter direction).
It is driven to rotate, and rotates while being in pressure contact with the surface of the photoconductor 1 and rubbing. Cleaning roller 1
2 has its surface portion pressed against the photosensitive member 1 so that the surface of the photosensitive member 1 can be elastically deformed, and a nip region N is formed at this pressed portion. The width of the nip region N in the circumferential direction of the photoconductor is, for example, about 1 mm, but the width of the nip region N is exaggerated in FIG.

In the nip region N, the transfer residual toner T ₁ having both positive and negative polarities is transferred to the cleaning roller 12 and the photosensitive member 1.
While being in contact with the surface of the toner, it is triboelectrically charged so that the toner has the same polarity (negative polarity in this example) as the toner at the time of development.
The transfer residual toner is triboelectrically charged between the cleaning member and the image carrier so that the transfer residual toner on the image carrier after the toner image transfer is aligned with the charging polarity (original polarity) of the toner during development. Is done.

The transfer residual toner T ₁ on the photoconductor 1 after the toner image is transferred onto the recording medium made of the transfer paper 16 is collected by a cleaning member composed of a cleaning roller 12 which rotates while being pressed against the photoconductor 1. However, when the toner is collected, the core member 12a of the cleaning roller 12 has a polarity opposite to the charging polarity of the toner frictionally charged by the cooperation of the roller 12 and the photoconductor 1, that is, a positive voltage in this example, For example, a voltage of +200 V is applied by the voltage power supply E ₄ .
Therefore, the residual toner after the transfer of the toner image that has passed through the transfer portion 8, that is, the transfer residual toner T ₁ frictionally charged between the cleaning roller 12 and the photoconductor 1 is the cleaning roller 12 to which a positive voltage is applied. Is electrostatically attracted to the surface of the roller, adheres to the surface of the roller 12, and is temporarily collected by this roller.

The potential of the surface of the photosensitive member 1 which has passed through the transfer roller 7 is, for example, about -50 V due to the influence of the transfer roller 7 to which a positive voltage is applied, but +200.
A cleaning roller 12 to which a voltage of V is applied,
The potential difference between the surface of the photoreceptor residual toner T ₁ is attached, the residual toner T ₁ of the negative charge polarity is of being electrostatically attracted to the surface of the cleaning roller 12. As a result, the surface of the photoconductor 1 is cleaned. In this way, the cleaning roller 12 that rotates in contact with the photoconductor 1 receives the transfer residual toner T ₁ on the photoconductor 1 between the cleaning roller 12 and the photoconductor 1.
In order to form an electric field that can be electrostatically attracted to the surface of the toner, a voltage having a polarity opposite to the charging polarity of the toner during development (positive in this example) is applied.

As described above, the cleaning roller 12
In the figure, the toner collected on the surface of the toner is indicated by reference numeral T ₂ . 3 to 9, the residual toner T ₁ of the the photosensitive member 1 is collected by the cleaning roller 12, then an example of an operation to re-adhered to the recovery toner T ₂ the surface of the photosensitive member 1 as described below FIG. 3 is an explanatory diagram, and FIG. 3 is a diagram illustrating a toner image on the photoconductor 1 that is transferred onto a transfer paper 16 that is conveyed in the direction of arrow P, and the transfer residual toner T _{1 on} the surface of the cleaning roller 12. It is a schematic diagram showing a situation when being collected.

As can be seen from FIG. 3, the surface portion of the photoconductor 1 that has been cleaned by the cleaning roller 12 is subjected to static elimination action by the static elimination lamp 13, and the surface potential thereof is lowered to the reference value. The charge eliminating lamp 13 continues to be turned on during the image forming operation. The surface of the photoconductor that has been subjected to the static elimination is continuously charged by the charging roller 2 as shown in FIG. 3, and the above-described image forming operation is continued.

In this way, one sheet of toner image is formed on the photoconductor 1 while the photoconductor 1 is rotated several times, for example.
This is continuously transferred onto the transfer paper 16, and the circumferential area on the photoreceptor 1 where such a toner image is formed is the image forming area. In FIG. 3, this image forming area is designated by a reference numeral X, and the tip end thereof in the rotation direction of the photosensitive member is designated by a reference numeral Y. Similarly, in FIG. 4, a symbol Z is attached to the rear end of the image forming area X in the rotation direction of the photoconductor.

When the leading edge Y of the image forming area X reaches the cleaning roller 12, the cleaning roller 1
The operation for collecting the transfer residual toner T ₁ to the second transfer toner T ₁ is started, and in the illustrated example, the operation for collecting the transfer residual toner T ₁ is continued until the trailing edge Z of the image forming area X reaches the cleaning roller 12. The portion of the image forming area X that has passed through the cleaning roller 12 has already been cleaned by the cleaning roller 12.

As shown in FIG. 4, when the rear end Z of the image forming area X in the direction of rotation of the photoconductor passes the charging roller 2, the charging roller 2 is separated from the surface of the photoconductor 1 at this time. (See Figure 5). At the same time, the switch S ₁₀ shown in FIG. 1 is switched to turn off the voltage application to the charging roller 2.

[0035] When the image forming region trailing Z passes the developing roller 5 of the developing device 4 as shown in FIG. 5, is switched switch S ₁ shown in FIG. 1, the developing roller 5 is voltage source E ₂
A positive polarity voltage opposite to the charging polarity of the toner, for example, a voltage of +500 V is applied to the developing roller 5 so that the toner does not adhere to the photoconductor 1. Subsequently, as shown in FIG. 6, when the trailing edge Z of the image forming area passes the transfer portion 8, at this time, the voltage application to the transfer roller 7 is stopped. At this time, in this example, the transfer roller 7 is separated from the photoconductor 1 (see FIG. 7).

The cleaning roller 12 electrostatically and temporarily collects the transfer residual toner T ₁ on the photoconductor ₁ to remove it.
Clean the surface of the toner, and then collect the collected toner T
₂ is redeposited on the surface portion of the photoconductor 1 that does not affect the formation of the electrostatic latent image. That is, when the trailing edge Z of the image forming area after the toner image is transferred onto the transfer paper 16 passes through the cleaning roller 12 as shown in FIG. 7, the switch S ₂ shown in FIG. 12
Is connected to a voltage power source E ₅ , and the core member 12a of the cleaning roller 12 has the same negative polarity as the charging polarity of the toner frictionally charged between the photoconductor 1 and the cleaning roller 12, for example, −3000V. Is applied.
In this way, the toner on the cleaning roller 12 is provided between the cleaning roller 12 and the non-image forming area W (FIG. 7) on the surface of the photosensitive member on the rear side in the rotation direction of the photosensitive member 1 with respect to the rear end Z of the image forming area. An electric field is formed in the direction in which T ₂ is emitted toward the photoconductor 1.

Due to the electric field, as shown in FIG.
The toner T ₂ temporarily collected on the cleaning roller 12 is reattached to the non-image forming area W on the photoconductor 1 and returned. At this time, the cleaning roller 12 of this example is
The photoconductor 1 is rotationally driven in the forward direction (counterclockwise in FIG. 1). Toner T redeposited on the photoconductor 1
_As shown in FIG. 9, the photoconductor ₃ passes under the charge removing roller 13 and the charging roller 2 separated from the photoconductor 1 by the subsequent rotation of the photoconductor 1, and reaches the developing device 4 as shown in FIG.

Here, as shown in FIG. 10, when the rear end Z of the image forming area X reaches the portion of the developing roller 5, the rotation direction of the roller 5 is switched, and the roller 5 is rotated by the photosensitive member 1.
The image bearing member is driven to rotate in the counter direction with respect to the rotating direction. The developing roller 5 rotates in the clockwise direction in the figure, that is, in the direction of the broken line arrow when collecting the redeposited toner T ₃ described below. Along with this, the developer (not shown) carried on the developing roller 5 is conveyed in the same direction.

On the other hand, the developer regulating member 18 is pivotally attached to the developing container 9 by a pivot pin 21 as shown in FIG. 2, and the solenoid 2 is connected via a connecting rod 22.
It is connected to 3 plungers. The connecting rod 22 is
Each end thereof is pivotally attached to the plunger of the solenoid 23 and the developer regulating member 18 via pins, respectively.

On the other hand, a blade-shaped developer regulating member 19 is also provided on the lower side of the developing roller 5 in the drawing, and the developer regulating member 19 is attached to the developing container 9 so as to be movable up and down. A plunger of a solenoid 26 is connected to one arm of an arm rod 25 pivotally supported by a pivot pin 24 on a side plate of an image forming apparatus main body (not shown), and a spring 27 serves to lower the habit of lowering the other arm. The lower end portion of the applied developer regulating member 19 is in contact.

As shown in FIG. 10, when the rear end Z of the development forming area X reaches the portion of the developing roller 5, the rotation direction of the roller is switched and both solenoids 2 shown in FIG.
3, 26 are excited at the same time. When the solenoid 23 on one side is excited, the developer regulating member 18 rotates clockwise around the pin 21 against the elastic force of the torsion coil spring 20 mounted on the pivot pin 21. .
That is, the developer regulating member 18 is located at a position where the protrusion 18a is separated from the developing roller 5 as shown in FIG. 10 from the developer conveying amount regulating position shown in FIGS. Move to a position where you do not do).

Further, when the other solenoid 26 is excited, the arm rod 25 is rotated around the pivot pin 24 in the clockwise direction in FIG. The member 19 moves upward to a position facing the developing roller 5 with a predetermined gap. That is, the developer regulation member 19 moves from the position shown in FIGS. 2 to 9 to the developer conveyance amount regulation position shown in FIG. The position of the developer regulating member 19 shown in FIGS. 2 to 9 is a position where the developer transport amount is not regulated.

In FIG. 10, the developer (not shown) carried by the developing roller 5 and conveyed in the direction of the broken arrow is scraped by the developer regulating member 19 which has moved to the regulating position. The transport amount of the developer carried and transported in the clockwise direction on the developing roller 5 is regulated. And
The redeposited toner T ₃ is electrostatically collected on the side of the regulated developer. As described above, since the developing roller 5 is applied with a positive polarity voltage opposite to the charging polarity of the toner at the time of development, as shown in FIG. 11, the negative polarity redeposition on the photoreceptor 1 is performed. The toner T ₃ is electrostatically transferred to the developing roller 5 side of the developing device 4 and is collected in the developer D in the developing container 9 (FIG. 1).

As described above, the cleaning roller 12
Electrostatically temporarily collects the transfer residual toner T ₁ on its surface, and then collects the recovered toner T ₂ on the formation of an electrostatic latent image on the image carrier composed of the photoconductor 1. The toner T _{3 that} is electrostatically redeposited on the non-existing surface portion and further redeposited on the surface of the image carrier is electrostatically collected on the developing roller side of the developing device 4. The toner collected in the developing device 4 is
It is reused in the developing device 4. In this way, the waste toner can be eliminated, and it is not necessary to provide a toner transport pipe for returning the toner collected by the cleaning roller 12 to the developing device 4.

When the image forming operation is continued,
When the next image forming area X1 shown in FIG. 9 and FIG. 10 is continuously subjected to the static elimination action by the static elimination lamp 13, and the leading end Y1 of the photoconductor rotating direction moves to the position of the charging roller 2, the charging roller 2 is exposed to light. By contacting the surface of the body 1 and negatively charging the next image forming area X1, an electrostatic latent image is formed on the next image forming area X1 in exactly the same manner as described above. As shown, it is visualized as a toner image in the developing device 4. At this time, of course, the negative voltage is applied to the developing roller 5. When the leading edge Y1 of the image forming area reaches the transfer section 8, the transfer roller 7 is pressed against the photoconductor 1, and the leading edge of the next transfer paper 16 reaches the transfer section 8, and the next image forming area X1 is reached.
The toner image formed on the transfer paper 16 is transferred to the transfer paper 16.
The transfer residual toner at this time is electrostatically temporarily collected by the cleaning roller 12 as described above, and the above-described operation is repeated. In this way, the image forming operation is repeated a predetermined number of times.

In the state shown in FIG. 9, neither the electrostatic latent image nor the toner image has been formed in the next image forming area X1. To be precise, the area X1 shown in FIG. It can be said that the area is to be the next image forming area. In addition, in FIGS. 1 and 3 to 12, the toners T, T ₁ , T ₂ , T on the photoconductor 1 or the cleaning roller 12 are shown.
_{As for 3} , these are schematically enlarged.

Further, when the leading edge Y1 of the next image forming area X1 reaches the developing section 6, the developing roller 5 for the re-adhered toner T ₃ is released.
Although the recovery to the side has already been completed, at this time, the excitation of both solenoids 23 and 26 shown in FIG. 2 is released, and the force of the springs 20 and 27 causes the developer regulating member 18 to move to the position shown in FIG.
2, the developer transport amount regulating position is moved to the original position, and the developer regulating member 19 is moved to a position where the developer transport amount is not regulated, as shown in FIG. At the same time, the rotation direction of the developing roller 5 is switched, and the developing roller 5 is rotated as shown in FIG.
As shown in (1), the photoconductor 1 rotates in the forward direction with respect to the rotation direction, and the electrostatic latent image formed in the image forming area X1 is visualized as a toner image. The developing roller 5 rotates in the rotation direction at the time of development, that is, in the direction in which the developing roller 5 and the photoconductor 1 are opposed to each other, the surfaces of both surfaces move in the same direction.

Here, in the conventional case, the redeposited toner T
₃ (FIGS. 10 and 11), the roller 5 was rotated in the same forward direction (counterclockwise direction in FIG. 10) as during development without switching the rotation direction of the developing roller 5. According to this, the developer on the developing roller 5 has a small mechanical scraping force, that is, a scavenging force, which acts on the redeposited toner T ₃ (FIGS. 10 and 11) on the photoconductor 1. As a result, the recovery efficiency of the re-adhered toner T ₃ decreases.

In the illustrated image forming apparatus, as a developer carrying / conveying member composed of the developing roller 5, during development, it rotates in the forward direction relative to the rotating direction of the image carrier composed of the photoconductor 1 to collect the redeposited toner. At times, since the developer carrying / conveying member whose rotation direction is switched and which rotates in the counter direction with respect to the rotation direction of the image carrier is used, not only is it possible to perform development so as to improve image quality,
The scavenging force can be increased at the time of collecting the re-adhered toner, whereby the re-adhered toner can be efficiently collected on the developer carrying and conveying member side.

When the re-adhered toner T ₃ on the surface of the image carrier made of the photoconductor 1 is collected to the side of the developer carrying and carrying member made up of the developing roller 5, the developer carrying and carrying member and the image carrying body are separated from each other. The rotation direction of the developer carrying / conveying member is set so that the surfaces of the two members move in opposite directions at the facing part (the closest part to each other), and the developer carried and carried on the carrying member is conveyed. Then, the re-adhered toner on the surface of the image carrier is efficiently collected to the developing device side by being conveyed in the same direction as the rotation direction of the conveying member. At this time, the rotation directions of the image bearing member and the developer carrying member are both clockwise and the same.

The switching of the rotation direction of the developing roller 5 and the operation timing of the developer regulating members 18 and 19 are not limited to the above-mentioned example, but various modifications can be made. In short, during development, the developing roller 5 moves in the forward direction with respect to the rotation direction of the photoconductor 1,
At the time of collecting the reattached toner, the rotation direction of the developing roller 5 may be controlled so that the development roller 5 is in the rotation direction of the photoconductor 1 and the counter direction.

In the illustrated image forming apparatus, as shown in FIG. 9, when the toner collected on the cleaning roller 12 has been redeposited on the photosensitive member 1, the cleaning roller 12 is developed again. When the cleaning roller 12 is driven to rotate in the counter direction with respect to the rotation direction of the photoconductor 1, for example, a positive polarity voltage opposite to the charging polarity of the toner at that time is applied, and the cleaning roller 12 originally adheres to the photoconductor 1. It is preferable to control the cleaning roller 12 so as to recover the toner when the toner that should not be present is attached even in a very small amount.

When a corona discharger separated from the photosensitive member 1 is used as the charging device, for example, the rear end Z of the image forming area X is not discharged by the discharger even after passing through the corona discharger. The surface of the photoconductor 1 can be continuously charged to the same polarity as the charging polarity of the toner (negative polarity in this example). In this case, the redeposited toner T ₃ shown in FIG.
Since the surface portion of the photoconductor 1 carrying the toner can be charged to, for example, −850 V having the same polarity as the charging polarity of the toner by the corona discharger, the re-adhered toner T ₃ faces the developing roller 5 of the developing device 4. Then, even when a voltage of, for example, −600 V having the same polarity as the charging polarity of the toner is kept applied to the developing roller 5, the re-adhered toner T ₃ is electrostatically applied to the developing roller 5. Can be collected. That is, even if the voltage applied to the developing roller 5 is not switched between the developing operation and the recovery of the re-adhered toner to the developing roller 5, the re-adhered toner is applied to the developing device 4.
It can be electrostatically recovered.

Further, the toner T ₂ collected on the cleaning roller 12 re-adheres to the non-image forming area W on the photoconductor 1, so that the re-adhered toner T ₃ causes electrostatic discharge during the above-mentioned image forming operation. Not only the latent image, but also the electrostatic latent image formed next is not affected. It is also possible to re-adhere the toner from the cleaning roller 12 to the rear portion of the image forming area X.

The point is that if the portion which should become the rear end Z of the image forming area X shown in FIG. 4 passes the cleaning roller 12 at a point before the state shown in FIG. After the recovery of the transfer residual toner T ₁ onto the cleaning roller 12 is completed, the re-adhesion operation of returning the recovered toner T ₂ on the cleaning roller 12 to the surface of the photoconductor 1 can be started. In this case, the re-adhesion operation of the toner to the photoconductor 1 is completed long before the rear end Z of the image forming area X reaches the portion of the cleaning roller 12 as shown in FIG. The transfer residual toner on the image forming area X may be collected by cleaning the surface portion of the photoconductor 1 to form the next electrostatic latent image on the cleaning surface. 3 to FIG.
The length of the non-image forming area between the image forming areas can be made shorter than in the example shown in FIG. 1, and the time required for the image forming operation can be shortened.

As described above, the collection of the transfer residual toner to the cleaning roller 12 and the re-adhesion of the collected toner to the photoconductor 1 can be performed in various modes. It is necessary to reattach the collected toner to the surface portion that does not affect the latent image formation.

The present invention can also be applied to an image forming apparatus configured to collect toner from the image bearing member or to reattach the collected toner to the image bearing member while the cleaning member is stopped.

Further, in the present invention, an image forming apparatus using not only a roller-shaped cleaning member but also an endless belt-shaped cleaning member, or a drum-shaped image carrier as well as an endless belt-shaped cleaning member is used. It is also applicable to an image forming apparatus, and also to an image forming apparatus of a type in which an intermediate transfer member is used as a recording medium, a toner image is transferred from an image carrier to this intermediate transfer member, and then this is transferred to a transfer material. Applicable. Further, according to the present invention, after the image bearing member is charged by the charging device, an electrostatic latent image is formed by a portion which is not irradiated with light at the time of image exposure on the surface thereof, and the electrostatic latent image is charged to a polarity opposite to the polarity of the latent image potential. It can also be applied to a so-called positive / positive developing type image forming apparatus in which toner is attached to the electrostatic latent image for development. The present invention is also applicable to an image forming apparatus using not only the above-mentioned two-component developer but also a one-component developer having no carrier as a developer.

[0059]

According to the image forming apparatus of the first aspect, the transfer residual toner is electrostatically collected on the cleaning member, and the collected toner is electrostatically redeposited on the image carrier, and the redeposited toner is re-adhered. In an image forming apparatus that electrostatically collects toner on the side of the developer carrying and conveying member of the developing device, a scavenger that acts on the redeposited toner on the image carrier at the time of collecting the redeposited toner to the developer carrying and conveying member. It is possible to prevent the aging force from becoming small, and the re-adhered toner can be efficiently collected on the developer carrying and conveying member side. .

[Brief description of drawings]

FIG. 1 is a partial cross-sectional explanatory view of an image forming apparatus according to an exemplary embodiment of the present invention, in which the toner on a photoconductor and a cleaning roller is schematically illustrated and enlarged.

FIG. 2 is an enlarged cross-sectional view of a developing device that is opposed to a photoconductor.

FIG. 3 is an explanatory diagram illustrating a relative positional relationship between a charging roller, a developing roller, a transfer roller, a cleaning roller, and a photoconductor, and illustrating a state in which residual toner remaining on the photoconductor is collected by the cleaning roller. Is.

FIG. 4 is an explanatory diagram similar to FIG. 3, showing a state in which a rear end of the image forming area reaches a portion facing a charging roller.

FIG. 5 is an explanatory diagram similar to FIG. 3, showing a state in which the rear end of the image forming area reaches a portion facing the developing roller.

FIG. 6 is an explanatory view similar to FIG. 3, showing a state when the rear end of the image forming area reaches a portion facing the transfer roller.

FIG. 7 is an explanatory diagram similar to FIG. 3, showing a state when the rear end of the image forming area reaches a portion facing the cleaning roller.

FIG. 8 is an explanatory diagram similar to FIG. 3, showing a state in which the collected toner on the cleaning roller is reattached to the photoconductor.

FIG. 9 is an explanatory view similar to FIG. 3, showing how redeposited toner on the photoconductor is conveyed toward the developing device.

FIG. 10 is an explanatory view similar to FIG. 3, showing a state in which the redeposited toner on the photoconductor reaches a portion of the developing roller and the redeposited toner is about to be collected on the developing roller side.

FIG. 11 is an explanatory view similar to FIG. 3, showing a state where the transfer residual toner in the non-image forming area on the photoconductor is collected by the developing roller.

FIG. 12 is an explanatory view similar to FIG. 3, showing a state when the leading edge of the next image forming area reaches a portion facing the transfer roller.

[Explanation of symbols]

4 Developing device T ₁ toner T ₂ toner T ₃ toner

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masako Yoshii 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (1)

[Claims] 1. An image carrier that is rotationally driven, a latent image forming unit that forms an electrostatic latent image on the carrier, and a developer carrying member that carries and carries a developer while rotating. After the toner image is transferred, the developing device has a developing device that visualizes the electrostatic latent image as a toner image by the conveyed developer, a transfer device that transfers the toner image on the image carrier to a recording medium, and Cleaning member that electrostatically temporarily collects the transfer residual toner on the image carrier and then reattaches the collected toner to the surface portion of the image carrier that does not affect the formation of the electrostatic latent image. In the image forming apparatus, which electrostatically collects the toner redeposited on the surface of the image carrier to the developer carrying and conveying member side of the developing device, the developing device visualizes the electrostatic latent image. At the time of development, the surface of the developer carrying member and the image carrying member are opposed to each other. Flip to move in a direction, yet when recovering redeposited toner on the surface of the image bearing member toward the developer carrying conveying member,
An image forming apparatus characterized in that a rotation direction of a developer carrying / conveying member is set so that surfaces of the developer carrying / conveying member and an image carrying member move in opposite directions to each other.