JPH09297517A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of recovering toner from a cleaning roller to a photoreceptor by using the cleaning roller rotating in a forward direction at the same linear velocity as the photoreceptor and using a developing roller rotating at higher linear velocity than the photoreceptor. SOLUTION: The cleaning roller 12 is rotated in the forward direction with respect to the rotating direction of the photoreceptor 1. A developer carrying and feeding member consisting of the developing roller 5 is rotated in the forward direction with respect to the rotating direction of the photoreceptor 1 in the case of recovery of reattached toner on the photoreceptor 1. If it is assumed that the linear velocity of the surface of the roller 12 at the time of reattaching the toner on the roller 12 to the photoreceptor 1 is Vc, the linear velocity of the surface of the roller 5 at the time of recovering the reattached toner on the photoreceptor 1 to the roller 5 is Vd, and the linear velocity of the surface of the photoreceptor 1 is Vp, they are set to Vc=Vp and Vc<Vd.

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 on 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 set the transfer rate of the toner image to 100%, and there is a problem in terms 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 that is electrostatically redeposited on the surface of the image bearing member that does not affect the formation of the electrostatic latent image, and the toner that is redeposited on the surface of the image bearing member is electrostatically collected by the developing device. A method of reusing in a developing device has been proposed (see, for example, Japanese Patent Publication No. 61-30274). This eliminates the need for a waste toner tank for storing the collected toner and a dedicated conveying means for transferring the collected toner to the developing device, etc., which can reduce the cost of the image forming apparatus and further recycle the toner. Since it can be used, waste toner can be eliminated.

In the image forming apparatus of this type that has been conventionally proposed, a developer is carried on a rotating developer carrying member and is carried, and the carried electrostatic latent image can be converted into a toner image. While the image is visualized, the cleaning member is brought into contact with the image carrier and is rotated, and the transfer residual toner on the image carrier is collected on the cleaning member side. Then, the toner redeposited on the image carrier is electrostatically collected on the side of the developer carrying and conveying member of the developing device.

By the way, in this type of image forming apparatus, when the toner collected by the cleaning member is re-adhered to the image carrier, the re-adhesion efficiency is low, and a part of the toner does not migrate to the image carrier, and cleaning is performed. The collected toner sometimes accumulated on the member. In this case, the toner recovery efficiency at the time of collecting the transfer residual toner is lowered, and the background stain on the image easily occurs. In addition, if a large amount of toner remains on the cleaning member, the toner may drop from the cleaning member and scatter. From these points, it is necessary to improve the efficiency of reattaching the toner from the cleaning member to the image bearing member and prevent a large amount of toner from accumulating on the cleaning member.

Further, even when the toner collected on the image carrier is collected on the side of the developer carrying and conveying member of the developing device, if the toner remains on the image carrier, scumming on the image is likely to occur. Become. From such a point, it is necessary to improve the efficiency of toner recovery to the developer carrying and conveying member.

Further, even in this type of image forming apparatus,
There is a demand for increasing the image forming speed as in a normal image forming apparatus that does not reuse the transfer residual toner.

However, in the image forming apparatus of this type which has been conventionally proposed, the re-adhesion efficiency of the toner from the cleaning member to the image carrier and the recovery efficiency of the toner from the image carrier to the developer carrying member and the image are In order to increase the formation speed, special consideration has been given to how to set the rotational directions of the process rotary elements such as the cleaning member, the image carrier, the developer carrying member and the speeds thereof. Therefore, it has not been possible to sufficiently increase the reattachment efficiency of toner from the cleaning member to the image carrier, the recovery efficiency of toner from the image carrier to the developer carrying member, and the image forming speed.

[0011]

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 above-mentioned problems in the image forming apparatus of the type in which the generated toner is electrostatically collected on the side of the developer carrying and conveying member of the developing device are solved, and the efficiency of re-adhesion of the toner from the cleaning member to the image carrier is improved. Another object of the present invention is to provide an image forming apparatus capable of enhancing the efficiency of toner recovery from the image bearing member to the developer carrying and transporting member and the image forming speed.

[0012]

In order to achieve the above-mentioned object, the present invention rotates an image bearing member that is rotationally driven, and a latent image forming unit that forms an electrostatic latent image on the bearing member. A developing device that carries and carries a developer on a developer carrying and carrying member, and a developing device that visualizes an electrostatic latent image as a toner image by the carried developer, and a toner image on an image carrier. And a transfer device that transfers the toner to the surface of the image carrier, and while rotating, electrostatically temporarily collects the transfer residual toner on the image carrier after the toner image transfer, and then collects the collected toner. ,
A cleaning member for electrostatically re-adhering to the surface portion of the image carrier that does not affect the formation of an electrostatic latent image, and the toner re-adhered to the surface of the image carrier is carried and carried by the developer of the developing device. In an image forming apparatus that electrostatically collects toner on the member side, when re-adhering the collected toner from the cleaning member to the image carrier, the surfaces of the cleaning member and the image carrier are in the same direction at the contact portion. The rotation direction of the cleaning member is set so that the cleaning member moves, and the number of rotations per unit time of the cleaning member is set so that the linear velocities of both surfaces become substantially equal. When the re-adhered toner is collected on the side of the developer carrying and conveying member, the developer carrying and conveying member is rotated so that the surfaces of the developer carrying and conveying member and the image carrier move in the same direction at the facing portion. While setting the direction, the number of revolutions per unit time of the developer carrying member is adjusted so that the linear velocity of the surface of the developer carrying member becomes larger than the linear velocity of the surface of the image carrier. An image forming apparatus characterized by the setting is proposed.

Further, in order to achieve the above object, the present invention has an image bearing member which is rotationally driven, a latent image forming means for forming an electrostatic latent image on the bearing member, and a rotating developer carrying member. A developing device that carries a developer on it and conveys it, and a developing device that visualizes an electrostatic latent image as a toner image by the conveyed developer, and a transfer device that transfers the toner image on the image carrier to a recording medium. The toner remaining on the image carrier after the toner image has been transferred is electrostatically temporarily collected while contacting the surface of the image carrier and rotating, and the collected toner is then collected on the image carrier. And a cleaning member for electrostatically re-adhering to a surface portion of the developing device that does not affect the formation of the electrostatic latent image of the toner. In an image forming apparatus that electrostatically collects an image, a cleaning member carries an image. When re-attached to the recovered toner, in the contact portion between the cleaning member and the image bearing member,
The rotation direction of the cleaning member is set so that both surfaces move in the same direction, and the number of rotations of the cleaning member per unit time is set so that the linear velocities of both surfaces become substantially equal. When the redeposited toner carried on the surface of the carrier is collected on the side of the developer carrying and transporting member, the surfaces of the developer carrying and transporting member and the image carrier may move in opposite directions to each other. An image forming apparatus is proposed in which the rotation direction of a developer carrying and conveying member is set.

In this case, in the above structure, when the re-adhered toner carried on the surface of the image carrier is collected on the side of the developer carrying member, the magnitude of the linear velocity on the surface of the developer carrying member is imaged. It is advantageous to set the number of revolutions per unit time of the developer carrying and conveying member so as to be larger than the linear velocity of the surface of the carrier.

[0015]

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 photoconductor 1 face each other (both are) when the developing device 4 develops the electrostatic latent image formed on the image carrier composed of the photoconductor 1 into a visible image. So that both surfaces move in the same direction.
It is driven to rotate counterclockwise in FIG.

In the present specification, the two rotating bodies which are opposed to each other and are parallel to each other are provided. The surfaces of the two rotating bodies at the facing portions (the contacting portions of the two or the closest portions of the two). When the two move in the same direction, they are said to be in the forward direction, and when their two surfaces move in opposite directions, the two are in the counter direction. When the rotating directions of both rotating bodies are forward, the rotating direction of one rotating body is clockwise and the rotating direction of the other rotating body is counterclockwise. When it is the counter direction, the rotation directions of both the rotating bodies are both clockwise or counterclockwise.

Therefore, the developing roller 5 is rotationally driven in the forward direction with respect to the rotational direction of the photoconductor 1 during development. The developing roller 5 rotates counterclockwise in FIG. 1 and the photoconductor 1 rotates clockwise, so that the rotation directions of both 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 photosensitive member 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).

As described above, the developing device 4 carries and carries the developer on the developer carrying and carrying member composed of the developing roller 5, and the electrostatic charge formed on the image carrier by the carried developer. The latent image is visualized as a toner image.

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 / conveying member including a developing roller 5 for carrying and carrying the developer while rotating. 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 on 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 moves in the clockwise direction in FIG. 1 (the direction of arrow a), that is, the direction in which the surfaces of the cleaning roller 12 and the photosensitive member 1 move in opposite directions (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 photoconductor 1 so that the surface of the photoconductor 1 is elastically deformed by the photoconductor 1, and a nip region N (FIG. 2) is formed at this pressure contact portion. The width of the nip area N in the circumferential direction of the photoconductor is, for example, about 1 mm.
Also, in FIG. 2, the width of the nip region N is exaggerated.

In the nip area 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 untransferred 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 between the roller 12 and the photoconductor 1, a positive voltage in this example, for example, +2.
A voltage of 00V is applied by the voltage power supply E ₄ . Therefore, the residual toner after the transfer of the toner image which 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 electrostatically attracted to the surface of the cleaning roller 12 to which a positive voltage is applied, and the surface of the roller 12 is And is temporarily collected by this roller.

The surface potential of the photoconductor 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 through 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.

[0042] 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. In this example, 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. 1 is switched. The cleaning roller 12 is connected to the voltage power source E ₅ , and the core member 12 a 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, a voltage of −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. During the process of re-adhering the toner from the cleaning roller 12 to the photoconductor 1, the rotation direction of the cleaning roller 12 is switched, and the cleaning roller 12 is exposed at the contact portion with the photoconductor 1 as shown in FIG. The surface facing the body is rotationally driven in the forward direction (counterclockwise in the figure) by a motor (not shown) so that the surface moves in the same direction as the surface of the photoconductor 1. During this rotation, the collected toner on the cleaning roller 12 is electrostatically redeposited and returned to the photoconductor 1. The return of the collected toner to the photoconductor side can also be performed by driving the photoconductor 1 and rotating the photoconductor 1 without driving the cleaning roller 12. The rotation directions of the cleaning roller 12 and the photoconductor 1 when reattaching the toner from the cleaning roller 12 to the photoconductor 1 will be described later in detail.

As shown in FIG. 9, the toner T ₃ redeposited on the photosensitive member 1 passes under the charge removing roller 13 and the charging roller 2 separated from the photosensitive member 1 by the subsequent rotation of the photosensitive member 1, as shown in FIG. The developing device 4 is reached as shown in FIG.

At this time, the developing roller 5 provided in the developing device 4 is rotationally driven in the forward direction (the direction of the arrow in the drawing) with respect to the rotating direction of the photoconductor 1, as in the case of development. The developer carried on the developing roller 5 is conveyed in the rotation direction of the developing roller 5, and at this time, the developer regulating member 18 shown in FIG. 1 receives a scraping action to regulate the conveying amount. Developer is photoconductor 1
And the developing roller 12 are opposed to each other, and the redeposited toner T ₃ shown in FIG. 10 is electrostatically transferred and collected on the developer side. As described above, the developing roller 5 has
Since the positive polarity voltage opposite to the charging polarity of the toner at the time of development is applied, as shown in FIG. 10, the negative polarity toner T ₃ redeposited on the photoconductor 1 is transferred to the developing roller 5 side. To the developer D in the developing container 9 (FIG. 1).
It is collected inside. The rotation direction of the developing roller 5 and the photoconductor 1 at the time of collecting the re-adhered toner to the developing roller 5 will be described in detail later.

As described above, the cleaning roller 12
Is an electrostatic latent image of the transfer residual toner T ₁ on the image bearing member after the toner image transfer on the surface of the cleaning roller 12 while being in contact with the surface of the image bearing member composed of the photoconductor 1 and rotating. And then collect the collected toner T ₂ .
It is electrostatically redeposited on the surface portion that does not affect the formation of the electrostatic latent image on the image carrier. The toner T ₃ redeposited on the surface of the image carrier is electrostatically collected by the developer carrying and conveying member of the developing device 4, that is, the developing roller 5 side. The toner collected in the developing device 4 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 conveying pipe or the like 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 charging the next image forming area X1 with a negative polarity, 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. 1 to 11, the toners T, T ₁ , T ₂ , T ₃ and T ₄ on the photoconductor 1 or the cleaning roller 12 are schematically enlarged.

As described above, the toner T ₂ collected on the cleaning roller 12 re-adheres to the non-image forming area on the photoconductor 1, so that the re-adhering toner T ₃ causes the toner T ₂ to remain static during the image forming operation. The electrostatic latent image formed next, as well as the electrostatic latent image, is not affected.

Here, the feature of this embodiment is that the transfer residual toner on the image carrier made of the photoconductor 1 is electrostatically collected by the cleaning member made of the cleaning roller 12, and then the collected toner is collected. When reattaching the cleaning member to the image bearing member, as described above, the rotation direction of the cleaning member is adjusted so that the surfaces of the cleaning member and the image bearing member are moved in the same direction at the contact portion. While setting in the forward direction with respect to the rotation direction of the body, the number of rotations per unit time of the cleaning member is set so that the linear velocities of both surfaces are substantially equal,
Moreover, when the re-adhered toner carried on the surface of the image carrier is collected on the side of the developer carrying member, as described above, at the facing portion of the developer carrying member and the image carrier, both surfaces have the same direction. The rotation direction of the developer carrying and conveying member is set to the forward direction with respect to the rotation direction of the image carrying body, and the magnitude of the linear velocity of the surface of the developer carrying and carrying member is set to the image carrying body. The number of rotations per unit time of the developer carrying / conveying member is set so as to be larger than the linear velocity of the surface of the.

That is, FIG. 8 shows the cleaning roller 1.
FIG. 2 is a diagram showing a state in which the collected toner on the cleaning member composed of 2 is reattached to the image carrier composed of the photoconductor 1, but the cleaning roller 12 in this drawing is arranged in the rotational direction of the photoconductor 1. Forward direction (counterclockwise in the figure)
To rotate. Further, as shown in FIG.
The developer carrying and transporting member composed of the developer carrying member, when collecting the redeposited toner T ₃ on the photoconductor 1,
Rotate in the forward direction.

Further, as shown in FIGS. 8 and 10, the linear velocity of the surface of the cleaning roller 12 when the toner on the cleaning roller 12 is reattached to the photosensitive member 1 is V
c, and the linear velocity of the surface of the developing roller 5 when the re-adhered toner T ₃ on the photoconductor 1 is collected by the developing roller 5 is Vd.
And the linear velocity of the surface of the photoconductor 1 is Vp, Vc = Vp and Vc <Vd are set.

Now, suppose that in the toner reattachment step,
If the cleaning roller 12 is rotated in the direction opposite to that of FIG. 8 and is rotated in the direction of arrow a in FIG. 2, one point P ₁ on the cleaning roller 12 and the photosensitive member 1
The upper one point P ₂ approaches each other and these points P ₁ , P ₂
After they touch each other, they are instantly separated. For this reason, the time during which the collected toner T ₂ on the cleaning roller 12 contacts the surface of the photoconductor 1 becomes extremely short, and it becomes difficult to electrostatically return the toner T ₂ to the surface of the photoconductor 1. Moreover, when the collected toner T ₂ on the cleaning roller 12 is reattached to the surface of the photoconductor 1, the cleaning roller 12 and the cleaning roller 12 are rotated in the counter direction.
Collected toner T ₂ passing through the nip region N between the photosensitive member 1 and the photoconductor 1
Since a large scraping force is exerted on the toner, the toner once transferred from the cleaning roller 12 to the surface of the photoconductor 1 by electrostatic force is adhered to the surface of the cleaning roller 12 again by the scraping action. is there.

This is the case with the cleaning roller 1.
When the toner on 2 is reattached to the photoconductor 1, even if the cleaning roller 12 is set in the forward direction with respect to the rotation direction of the photoconductor 1 as in FIG.
This also occurs when the surface linear velocity Vc of 2 is set to be significantly larger than the surface linear velocity Vp of the photoconductor 1.

As described above, when the efficiency of reattaching the toner on the cleaning roller 12 to the photosensitive member 1 decreases, the amount of toner remaining on the cleaning roller 12 increases, and a large amount of toner remains on the cleaning roller 12. Will be accumulated. In this case, the efficiency at the time of collecting the transfer residual toner on the photoconductor 1 by the cleaning roller is lowered, and the toner image on the photoconductor is stained. When a large amount of toner accumulates on the cleaning roller 12, it may fall downward and scatter.

On the other hand, when the collected toner on the cleaning roller 12 is reattached to the surface of the photoconductor 1,
2, the cleaning roller 12 is rotated in the forward direction with respect to the rotation direction of the photoconductor 1, the cleaning roller 12 is rotated in the direction of the arrow b in FIG. Linear velocity V
If the magnitudes of c and Vp are set to be almost equal, the nip area N
Since the cleaning roller 12 and the photoconductor 1 are kept in contact with each other for a certain time, the electrostatic force can be applied to the toner for a relatively long time. As a result, the toner on the cleaning roller 12 can be efficiently transferred to the photoconductor. Moreover, since the toner between the cleaning roller 12 and the photoconductor 1 is not excessively scraped off, the cleaning roller 12 removes the photoconductor 1 from the cleaning roller 12.
It is possible to prevent the phenomenon in which the toner electrostatically transferred to the surface of the sheet is scraped back to the cleaning roller 12 and returned.

In this way, the cleaning roller 12
To improve the re-adhesion efficiency of the toner from the toner to the photoconductor 1, prevent a large amount of toner from accumulating on the cleaning roller 12, enhance the cleaning efficiency for the photoconductor 1, and effectively suppress the occurrence of the background stain of the toner image. Therefore, a high quality toner image can be obtained.

When toner is reattached to the photosensitive member 1 from the cleaning roller 12, the cleaning roller 1
If the linear velocity Vc of the surface of 2 is set slower than the linear velocity Vp of the surface of the photoconductor 1 and Vc <Vp, all the collected toner adhering to the peripheral surface of the cleaning roller 12 is photoconductor 1.
It takes a long time to finish reattaching to the surface of.
For this reason, the circumferential length of the redeposition region for redepositing the toner on the photoconductor 1 becomes long. Since a toner image cannot be formed in this area and this area becomes a non-image area, if this area becomes long, the non-image area W (FIGS. 8 and 9) will expand. When the non-image area is enlarged, the preceding transfer paper 1
6 and the transfer paper 16 that follows, that is, the distance between papers becomes long. As a result, the image forming speed becomes slow.

When the collected toner is reattached to the photosensitive member, the linear velocity Vc of the cleaning roller 12 is made equal to the linear velocity Vp of the photosensitive member 1 to prevent the image forming speed from being slowed down and to perform cleaning. It is possible to prevent the efficiency of toner recovery from the roller 12 to the photoconductor 1 from decreasing.

Further, in the image forming apparatus of this embodiment, when the redeposited toner T ₃ on the photoconductor 1 is collected by the developing roller 5, the surfaces of the developing roller 5 and the photoconductor 1 are moved in the same direction. The developing roller 5 is rotationally driven. In this case, as described above, the unit of the developing roller is set so that the magnitudes of the linear velocities Vp and Vd of the surface of the developing roller 5 and the photosensitive member 1 are Vd> Vp. The number of rotations per hour is set. Therefore, the developer carried on the developing roller 5 gives a large scraping force to the redeposited toner on the photoconductor 1,
By the cooperation of this force and the electrostatic force, the re-adhered toner T ₃ on the photoconductor can be efficiently collected on the developing roller 5 side. As a result, it is possible to prevent the toner from remaining on the photoconductor 1 and effectively suppress the problem that the toner image formed on the photoconductor 1 has a background stain.

If the developing roller 5 is rotated at a linear velocity lower than the linear velocity of the photosensitive member 1, the developer on the developing roller 5 will be removed from the redeposited toner T ₃ on the photosensitive member. The resulting scraping action becomes weak, and the toner may remain on the photoconductor. The efficiency with which the toner is collected on the developing roller is reduced. On the other hand, in the image forming apparatus of this example, the efficiency of collecting toner to the developing roller 5 can be improved as described above.

The linear velocity Vd of the developing roller 5 and the linear velocity Vp of the photosensitive member 1 can be set to Vd = 2 to 3 times Vp as one example. Even when the developing device 4 visualizes the electrostatic latent image on the photoconductor 1, the developing roller 5 can be rotated at the same speed.

In the structure of the image forming apparatus described above, the re-adhered toner T ₃ on the photoconductor 1 is transferred to the developing roller 5.
When electrostatically collecting to the side of the developing roller 5 and the photosensitive member 1.
It is also possible to set the rotation direction of the developing roller 5 so that the surfaces of the two surfaces move in opposite directions at the portion facing each other. Even with this structure, when the re-adhered toner T ₃ on the photoconductor 1 is collected by the developing roller 5,
The difference in linear velocity between the surface of the photosensitive member 1 and the surface of the photosensitive member 1 can be made large, and the efficiency of collecting the redeposited toner can be improved. In this case, the magnitude of the linear velocity Vd on the surface of the developing roller 5 and the magnitude of the linear velocity Vp on the surface of the photoconductor 1 may be set equal (both directions are opposite to each other), but in this case However, if the former size is made larger than the latter size, the efficiency of collecting the re-adhered toner can be further improved. When the redeposited toner carried on the surface of the image carrier is collected on the side of the developer carrying member, development is performed so that the surfaces of the developer carrying member and the image carrier move in opposite directions to each other. Even when the rotation direction of the agent carrying member is set,
The number of revolutions per unit time of the developer carrying and conveying member is set so that the magnitude of the linear velocity of the surface of the developer carrying and conveying member becomes larger than the magnitude of the linear velocity of the surface of the image carrier. Also in this case, for example, the linear velocity V of the surface of the developing roller 5
The magnitude of d can be set to, for example, about 2 to 3 times the magnitude of the linear velocity Vp of the surface of the photoconductor 1.

As described above, the cleaning roller 1
It is possible to improve the re-adhesion efficiency of the toner from the photoconductor 1 to the photoconductor 1, the efficiency of collecting the toner from the photoconductor 1 to the developing roller 5, and the image forming speed.

When the transfer residual toner on the photoconductor 1 is collected by the cleaning roller 12, the cleaning roller 12 is countered with respect to the rotation direction of the photoconductor 1 in the above-described embodiment, as shown in FIG. Although the roller is rotated in the direction (clockwise in the figure), of course, the transfer residual toner can be collected by rotating the roller in the forward direction with respect to the rotation direction of the photoconductor 1.

However, when the cleaning roller 12 collects the transfer residual toner on the photosensitive member 1 in the forward direction with respect to the rotating direction of the photosensitive member 1, it will be described as follows. This can cause problems, and in such cases it is desirable to rotate the cleaning roller 12 in the counter direction and rotate it less than one revolution. The reason is as follows.

During the image forming operation described above, the transfer residual toner T ₁ on the photosensitive member 1 which has passed through the transfer portion 8 shown in FIG.
Contains mixed toner (referred to as abnormal polarity toner) having a polarity opposite to the charge polarity of the toner at the time of development due to the influence of transfer charging, and in this example, the abnormal polarity toner is shown in FIG. In addition, triboelectric charging is carried out at a portion of the nip area N so that the toner has the same polarity as the charging polarity of the toner at the time of development. However, it is difficult to completely align the charging polarities of the transfer residual toners existing in the nip area N shown in FIG. 2, and in some cases, the toners having the charging polarities opposite to the charging polarities of the toners at the time of development, that is, The abnormal polarity toner may exist. When the toner on the photoconductor 1 is collected by the cleaning roller 12 during a normal image forming operation, a voltage having a polarity opposite to the charging polarity of the toner at the time of development is applied to the cleaning roller 12 as described above, and The toner having the charging polarity is electrostatically transferred to the cleaning roller 12 and is collected by the roller 12, but at this time, the toner having the polarity opposite to the charging polarity at the time of development (abnormal The polar toner) also adheres to the surface of the cleaning roller 12 due to the mechanical scraping force received from the cleaning roller 12. If such abnormal polarity toner is transferred to the photoconductor 1 during the operation of collecting the toner from the photoconductor 1, background stains on the image and stains on the charging roller 2 are likely to occur.

Therefore, as shown in FIG. 2, when the transfer residual toner T ₁ is collected from the photoconductor 1 to the cleaning roller 12 in the normal image forming operation, the contact area between the photoconductor 1 and the cleaning roller 12, that is, In the nip region N where these are in pressure contact, the rotation direction of the cleaning roller 12 is controlled so that the surfaces of both of them move in opposite directions (counter direction), and the rotation of the cleaning roller 12 is less than one rotation. the residual toner T ₁ of the the photosensitive member 1 so as to recover the cleaning roller 12, by controlling the rotation of the cleaning roller 12, the toner T _2, which is collected by the cleaning roller 12 is, in its toner recovery operation, again There is no contact with the photoconductor 1. Moreover, it is possible to prevent the abnormal polarity toner collected on the cleaning roller 12 from being electrostatically transferred to the surface of the photoconductor 1 after cleaning during the toner collecting operation.

The transfer residual toner T ₁ is transferred to the cleaning roller 1.
2, when the cleaning roller 12 is rotated in a direction in which the cleaning roller 12 moves in the same direction (forward direction) in the nip region N with the photoconductor 1, as shown by a chain line arrow b in FIG. The collected toner T ₄ is present on the cleaning roller 12 on the downstream side in the rotation direction of the body 1,
When this toner T ₄ was under an abnormal polarity toner charged to the positive polarity, the cleaning roller 12, when the toner is collected at the same the voltage of the same positive polarity is applied, the toner T ₄ of the positive polarity The photoconductor 1 may be electrostatically attracted and adhere to the photoconductor surface. In this case, the cleaning failure of the photoconductor 1 occurs, and the toner adheres to the charging roller 2, so that the toner image formed subsequently has a background stain. For this reason, at the time of collecting the transfer residual toner on the photoconductor, the cleaning roller 12 rotates in the counter direction with respect to the rotation direction of the photoconductor 1, that is, in the direction of the solid arrow a in FIG. It is desirable to set the rotation direction.

Further, when the cleaning roller 12 is rotated once or more to collect the transfer residual toner from the photoconductor 1, the toner collected by the cleaning roller 12 contains the abnormally charged positive polarity toner. Then, when it approaches the photoconductor 1 again or comes into contact with the photoconductor 1, the toner adheres to the photoconductor 1 and cleaning failure of the photoconductor 1 occurs. For this reason, it is desirable to finish the toner collecting operation from the photoconductor 1 to the cleaning roller 12 while the cleaning roller 12 is rotationally driven for less than one rotation.

Here, as shown in FIG. 3, the photosensitive member 1 and the cleaning roller are arranged so that the cleaning roller 12 is rotated in the counter direction when the transfer residual toner is collected with respect to the rotating direction of the photosensitive member 1. When the linear velocities of the respective surfaces of 12 are Vp and Vc, respectively, the diameter of the cleaning roller 12 can be reduced by setting the magnitude relationship of the respective linear velocities to Vc <Vp.

The reason therefor will be described. The cleaning roller 12 collects the transfer residual toner on the photoconductor 1 and reattaches the collected toner to the photoconductor. The former is the cleaning roller. Is photoconductor 1
Since the toner rotates in the counter direction with respect to the rotation direction of the photosensitive drum 1 and rotates less than one rotation, in order to collect the transfer residual toner in the long peripheral surface area (image forming area) on the photosensitive member 1 without leaving the cleaning roller, Needs to be rotated at a linear velocity lower than the linear velocity of the photoconductor 1.

When the cleaning roller 12 is rotated at a high linear velocity with respect to the photoconductor 1 or at the same linear velocity, the transfer residual toner in the relatively long peripheral surface area on the photoconductor 1 is removed. In order to collect the cleaning roller 12 in a range of less than one rotation, it is necessary to increase the circumferential length of the cleaning roller, in other words, increase the diameter of this roller.

As the diameter of the cleaning roller 12 increases, the cleaning device 15 shown in FIG.
As a result, the image forming apparatus becomes large. In turn, the linear velocity Vc (Fig. 3) of the cleaning roller 12 is
By making the linear velocity Vp of the photoconductor 1 slower, that is, Vc <Vp, for example, Vc≈ (1/7) Vp, it is not necessary to increase the diameter of the cleaning roller, and the image forming apparatus becomes large-sized. There is nothing to do. At that time, as described above, the surface linear velocity Vd of the developing roller 5 at the time of development is faster than that Vp of the photosensitive member 1, for example, 2 of Vp.
Since it is set to 3 times, the magnitude of each surface linear velocity is
It is set to Vd>Vp> Vc.

Further, the developer D of the developing device 4 shown in FIG.
Some of the toner is returned to the developing device 4 through the cleaning roller 12. Thus, it is not uncommon for paper powder to be mixed in the toner returned to the developing device 4. When the paper dust is mixed in the developer D in this way, the paper dust is clogged between the developing roller 5 and the developer regulating member 18, whereby a so-called white stripe is formed on the toner image formed on the photoconductor 1, and The image quality may deteriorate. Therefore,
As shown by reference numeral 20 in FIG. 12, a paper dust removing filter composed of a net, a brush or the like is provided in the moving path of the developer carried by the developing roller 5 and conveyed. The paper dust in the developer conveyed on the developing roller 5 toward 20 may be removed. As a matter of course, the filter 20 allows the developer to pass therethrough, but does not allow the passage of other paper dust or the like.

The stirring paddles 10A and 10B shown in FIG.
As described above, the toner frictionally charges the toner to the charging polarity at the time of development.
As shown in FIG. 13, the paper pad removing filter 21 is provided on the paddle shaft 26, and the stirring paddle 10A is used.
When the paper is rotated, the paper dust 22 (enlarged for convenience in the figure) may be removed at the portion 21. The other stirring paddle 10B can have the same configuration.

Further, when the toner is collected from the photoconductor 1 to the developing roller 5, the toner may be scattered out of the developer container 9 through the gap 23 between the developing container 9 and the photoconductor 1 shown in FIG. is there.

Therefore, as shown in FIG. 14, a casing portion 9A extending from the middle portion of the developing container 9 toward the photoconductor 1 is provided outside the developing container 9, and the casing portion 9A
By disposing the fan 24 and the developer removing filter 25 side by side in the cylindrical protrusion 9A ₁ that extends downward, it is possible to prevent the toner from scattering.

When the fan 24 is rotated, an air flow in the direction of arrow f is generated, and the toner is guided to the portion of the filter 25 by riding on this air flow, and the toner is prevented from coming out of the filter 25 at this portion. Can be stopped by. In any case, it is possible to prevent the toner from scattering outside the developing device. The fan 24 may be operated only when the re-adhered toner on the photoconductor 1 is collected by the developing roller 5, or may be always operated.

In the embodiment described above, the transfer residual toner is removed from the cleaning roller 1 for each image forming area X.
2 is collected and re-adhered on the photoconductor 1 each time, but the transfer residual toner of a plurality of image forming areas is
It is also possible to collect each of the collected toners on the cleaning roller 12 every time image formation is performed, and reattach the collected toners to the photoconductor 1 all together. That is, the cleaning roller 12
1 is rotated, for example, in the direction a in FIG. 1 to collect the residual toner after each image formation, and after the plurality of times of collection is completed, the cleaning roller 12 is indicated by an arrow a in FIG. It is also possible to rotate the toner in the direction opposite to the direction and collectively reattach the toner collected for each image formation onto the photoconductor 1.

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.

[0083]

According to the image forming apparatus of the first to third aspects, the transfer residual toner is electrostatically collected on the cleaning member, and the collected toner is electrostatically redeposited on the image carrier and re-attached. In an image forming apparatus that electrostatically collects adhered toner to the side of the developer carrying and conveying member of the developing device, re-adhesion efficiency of toner from the cleaning member to the image carrier, The toner collection efficiency and the image forming speed can be increased.

[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 schematic illustration of a frictional contact portion between a photoconductor and a cleaning roller and a toner for explaining that the charging polarities of the toner are made uniform.

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 collected on the developing roller side.

FIG. 11 is an explanatory diagram similar to FIG. 3, showing a state when the leading edge of the next image forming area reaches a portion facing the transfer roller.

FIG. 12 is an enlarged cross-sectional view of the developing device shown in FIG. 1, showing an example in which a paper dust removing filter is provided.

FIG. 13 is a side view showing a part of a stirring paddle provided in the developing device and having a paper dust removing function.

FIG. 14 is a partial cross-sectional view of a developing device including a toner scattering prevention device.

[Explanation of symbols]

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

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

Claims (3)

[Claims] 1. An image bearing member that is driven to rotate, a latent image forming unit that forms an electrostatic latent image on the bearing member, and a developer that is carried and conveyed on a rotating developer carrying member. 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 a contact device that contacts the surface of the image carrier and While rotating, the transfer residual toner on the image carrier after the toner image transfer is electrostatically temporarily collected, and then the collected toner is
A cleaning member for electrostatically re-adhering to the surface portion of the image carrier that does not affect the formation of an electrostatic latent image, and the toner re-adhered to the surface of the image carrier is carried and carried by the developer of the developing device. In an image forming apparatus that electrostatically collects on the member side, when re-adhering the collected toner from the cleaning member to the image carrier, the surfaces of the cleaning member and the image carrier are in the same direction at the contact portion. The rotation direction of the cleaning member is set so that the cleaning member moves, and the number of rotations per unit time of the cleaning member is set so that the linear velocities of both surfaces are substantially equal to each other. When the re-adhered toner is collected on the side of the developer carrying and conveying member, the developer carrying and conveying member is rotated so that the surfaces of the developer carrying and conveying member and the image carrier move in the same direction. In addition to setting the rotation direction, the number of rotations per unit time of the developer carrying and conveying member so that the magnitude of the linear velocity of the surface of the developer carrying and conveying member becomes larger than the magnitude of the linear velocity of the surface of the image carrier. The image forming apparatus is characterized by setting. 2. An image bearing member that is driven to rotate, a latent image forming unit that forms an electrostatic latent image on the bearing member, and a developer that is carried and conveyed on a rotating developer carrying member. 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 a contact device that contacts the surface of the image carrier and While rotating, the transfer residual toner on the image carrier after the toner image transfer is electrostatically temporarily collected, and then the collected toner is
A cleaning member for electrostatically re-adhering to the surface portion of the image carrier that does not affect the formation of an electrostatic latent image, and the toner re-adhered to the surface of the image carrier is carried and carried by the developer of the developing device. In an image forming apparatus that electrostatically collects on the member side, when re-adhering the collected toner from the cleaning member to the image carrier, the surfaces of the cleaning member and the image carrier are in the same direction at the contact portion. The rotation direction of the cleaning member is set so that the cleaning member moves, and the number of rotations per unit time of the cleaning member is set so that the linear velocities of both surfaces become substantially equal. When the re-adhered toner is collected on the side of the developer carrying and conveying member, the developer carrying and carrying member is arranged so that the surfaces of the developer carrying and carrying member and the image carrying body move in opposite directions to each other. An image forming apparatus, wherein the rotation direction of the image forming apparatus is set. 3. When the redeposited toner carried on the surface of the image carrier is collected on the side of the developer carrying member, the magnitude of the linear velocity on the surface of the developer carrying member is larger than that of the surface of the image carrying member. The image forming apparatus according to claim 2, wherein the number of revolutions of the developer carrying and conveying member per unit time is set so as to be higher than the linear velocity.