JPH09319276A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recover toner left after transfer on a photoreceptor by the surface of a cleaning roller to which toner does not adhere and to enhance recovering efficiency by providing a damming member damming and accumulating the toner recovered on the cleaning roller from the photoreceptor. SOLUTION: The damming member 21 damming the toner recovered on the cleaning roller 12 when the toner left after transfer T1 is recovered from the photoreceptor 1 on the roller 12 and accumulating the toner to be restored from the roller 12 to the photoreceptor 1 is provided in the casing 17 of a cleaning device 18. That means, the recovered toner on the roller 12 is dammed by the member 21 and temporarily scraped from the roller 12. Therefore, the toner left after transfer T1 on the photoreceptor 1 is recovered by the surface of the roller 12 to which the toner does not adhere after passing the member 21.

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, various cleaning devices for cleaning the image bearing member have been proposed and put into practical use, but conventional cleaning devices generally store toner collected from the image bearing member in a waste toner tank or the like. , 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 that is electrostatically redeposited on the surface portion of the image bearing member that does not affect the formation of the electrostatic latent image, and the toner that is redeposited on the image bearing member surface is electrostatically collected by the 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 means for transferring the collected toner to the developing device, so that the cost of the image forming apparatus can be reduced and the toner can be recycled. Therefore, the waste toner can be eliminated.

In this type of image forming apparatus, the cleaning member performs an operation of collecting the transfer residual toner on the image carrier and a toner re-adhesion operation of returning the recovered toner to the surface of the image carrier while rotating. All the toner on the cleaning member cannot be returned to the surface of the image carrier by the re-adhesion operation, and some toner remains on the surface of the cleaning member after the toner re-adhesion operation is completed. For this reason, the transfer residual toner on the image carrier must be collected by the surface of the cleaning member on which the toner adheres. However, if the transfer residual toner is collected by such a cleaning member, the recovery efficiency decreases, and the surface of the image carrier is reduced. A small amount of toner remains on the surface, which appears as a background stain on the toner image.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to electrostatically collect transfer residual toner on a cleaning member, and then electrostatically redeposit the recovered toner on an image carrier.
To solve the above-mentioned problems in the image forming apparatus of the type in which the re-adhered toner is electrostatically collected by the developing device, and the toner adheres to the surface portion of the cleaning member that collects the transfer residual toner on the image carrier. An object of the present invention is to provide an image forming apparatus capable of preventing such a situation and improving the efficiency of collecting the transfer residual toner.

[0008]

In order to achieve the above object, the present invention is directed to an image carrier which is driven to rotate, a latent image forming means for forming an electrostatic latent image on the carrier, and an electrostatic latent image forming means. A developing device that visualizes the latent image as a toner image, a transfer device that transfers the toner image on the image carrier to a recording medium, and a transfer residual toner on the image carrier after the toner image transfer while rotating. A cleaning member for electrostatically temporarily collecting and then electrostatically redepositing the collected toner on the surface portion of the image carrier that does not affect the formation of the electrostatic latent image. In an image forming apparatus that electrostatically collects the toner redeposited on the surface of the carrier to the developing device, when collecting the transfer residual toner from the image carrier to the cleaning member, the toner collected in the cleaning member is dammed, and From the cleaning member to the image carrier We propose an image forming apparatus characterized in that a save up damming member a toner for returning the image bearing member during toner reattachment (claim 1).

At this time, in the image forming apparatus according to the first aspect, the damming member is pressed against the cleaning member to collect the toner from the cleaning member to the image bearing member when the transfer residual toner is collected from the image bearing member to the cleaning member. It is advantageous to provide a damming member actuating means for actuating the damming member so that the contact force with respect to the cleaning member is weakened or is separated from the cleaning member when re-adhering.

Further, in the image forming apparatus according to the first or second aspect, it is advantageous that the dam member is disposed opposite to the peripheral surface portion of the cleaning member facing the image carrier surface. (Claim 3).

Further, in the image forming apparatus according to any one of claims 1 to 3, the toner is electrostatically attracted from the cleaning member to the dam member when the transfer residual toner is collected from the image carrier to the cleaning member. It is advantageous to provide voltage applying means for applying a voltage to the damming member so that the electric field of (1) is formed between the cleaning member and the damming member (claim 4).

Further, in the image forming apparatus according to any one of claims 1 to 4, when the toner is reattached from the cleaning member to the image carrier, the electric field in the direction in which the toner moves from the damming member to the cleaning member is cleaned. It is advantageous to provide voltage applying means for applying a voltage to the dam member so as to be formed between the member and the dam member (claim 5).

Further, in the image forming apparatus according to any one of claims 1 to 5, it is advantageous that the cleaning member is an endless belt wound around a plurality of pulleys (claim 6).

In the image forming apparatus according to any one of claims 1 to 6, the cleaning member is an endless belt wound around a plurality of pulleys, and the dam member is not wound around the pulleys. Advantageously, the backup member is provided so as to abut on the belt portion in the free state and to come into contact with the back surface portion opposite to the abutting belt portion surface (claim 7).

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. First, the basic configuration of the image forming apparatus and its operation will be clarified.

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 configuration of an image carrier is rotationally driven in a fixed direction by a drive device (not shown), in the present example, clockwise in FIG. 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 the charging device, after being initialized by the static elimination lamp 13 which is an example. In this example, the charging roller 2 is connected to the voltage power source E ₁₀ , and while being in contact with the photoconductor 1 and rotating, the surface of the photoconductor 1 is uniformly charged to a negative polarity of −850V, for example. 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 section 3, for example, an exposure scanning device including a laser device (not shown) performs optical writing scanning with the light-modulated laser beam 11, so that the surface of the photoconductor 1 is exposed. A predetermined electrostatic latent image is formed. The surface potential of the portion A of the photoconductor 1 irradiated with the laser beam 11, that is, the surface potential of the electrostatic latent image is, for example, −1.
The surface potential of the portion B where the laser beam 11 is not irradiated, that is, the background portion of the electrostatic latent image is approximately −85.
It is maintained at 0V. Thus, in this example, the charging roller 2
The charging device including the charging device and the exposure scanning device described above include the photosensitive member 1.
A latent image forming means for forming an electrostatic latent image on the image carrier.

The developing device 4 is provided with a developing roller 5 which is an example of a developer carrying and conveying member arranged to face the photoconductor 1, and a pair of stirring paddles 10A and 10B, which are provided in a developing container 9, respectively. And is rotatably supported in the developing container 9. A voltage having the same polarity as the charging polarity of the photoconductor ₁ of, for example, about −600 V is applied to the developing roller 5 by the voltage power source E ₁ .

In the developing device 4 shown here, a two-component developer D having a toner and a magnetic carrier is used, and the developer D is contained in a developing container 9. Then, as the stirring paddles 10A and 10B rotate, the toner is charged to a predetermined polarity by friction with the carrier, that is, the same polarity as the charging polarity of the photoconductor 1 in this example, that is, a negative polarity. As described above, in the image forming apparatus of this example, the charging polarity of the toner at the time of development for visualizing the electrostatic latent image is negative, as described below. A developing device using a one-component developer having no carrier may be employed.

The developing roller 5 is rotationally driven counterclockwise in the drawing, and the magnetic force of a magnet (not shown) provided in the developing roller 5 causes the developer carried on the peripheral surface of the developing roller 5 to be removed. The developing roller 5 is conveyed in the rotation direction of the developing roller 5 and is scraped by the developer regulating member 15 which is opposed to the developing roller 5 with a predetermined gap. The developer whose conveyance amount is regulated by the developer regulating member 15 is conveyed toward the developing section 6 where the developing roller 5 and the photoconductor 1 face each other, and the toner in the developer is conveyed to the photoconductor by the developing section 6. 1 is electrostatically attracted to the electrostatic latent image on 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, adheres to the surface portion A of the photoconductor irradiated with the laser beam, and the electrostatic latent image is visualized as a toner image. As described above, the image forming apparatus of this embodiment employs the reversal development method (negative / positive development method).

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 in which the surface moves in the same direction as the surface of the photoconductor at the part facing the photoconductor 1, and the transfer part between the transfer roller 7 and the photoconductor 1 facing the transfer roller 7 is rotated. Transfer paper 1 toward 8
The recording medium composed of 6 is sent in the direction of arrow P. Transfer part 8
Transfer roller 7 is transferred to photoconductor 1 via transfer paper 16 sent to
Is pressed against the surface of the
The toner image formed on the photoconductor 1 is transferred onto the transfer paper 16. That is, the transfer roller 7 is driven 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 16. A transfer device separated from the photoconductor 1;
For example, a transfer device composed of a corona discharger can be used.

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 includes the image carrier composed of the photoconductor 1 which is rotationally driven in a fixed direction.
Latent image forming means for forming an electrostatic latent image on the image carrier,
Developing device 4 for visualizing the electrostatic latent image as a toner image
And a transfer device including a transfer roller 7 for transferring the toner image on the image carrier onto a recording medium including transfer paper 16, and a cleaning member including a cleaning roller 12 described below, and the above-described cleaning member. A static eliminator including a static eliminator lamp 13 is provided. A charging device, an exposure unit 3 for the image carrier by the latent image forming means, a developing device 4, a transfer device,
The cleaning member and the static eliminator 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 temporarily collected on the surface of the cleaning roller 12, which is an example of a cleaning member.

The cleaning roller 12 has, for example, a conductive core member 12a made of a rigid body, and a medium resistance elastic body 12b fixed on the surface of the core member 12a. The member 12a is made of a round shaft-shaped 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 casing 17 and has a core member 12a.
The respective end portions of are respectively rotatably supported on the front and rear side walls of the casing 17. As described above, the cleaning device 18 includes the cleaning member including the cleaning roller 12 and the casing 17 that accommodates the cleaning member 12. The cleaning roller 12 together with the developing roller 5, the charging roller 2, and the transfer roller 7. , Substantially parallel to the photoconductor 1.

Here, in FIG. 1, most of the toner T of the toner image directed from the developing unit 6 to the transfer unit 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 pressure contact portion between the cleaning roller 12 and the photosensitive member 1, that is, the cleaning portion 14 in a state where the toners of both positive and negative polarities are mixed.

The cleaning roller 12, when collecting the residual toner T ₁ of the the photosensitive member 1, by a driving device, not shown, is driven to rotate in the appropriate direction, counterclockwise direction in FIG. 1 in the example shown ( Rotate in the direction of arrow a). The cleaning roller 12 rotates in a direction in which the surface of the cleaning roller 12 faces the surface of the photoconductor 1 in the circumferential direction at a portion facing the photoconductor 1. At this time, the cleaning roller 12
Rotates while rubbing its surface against the surface of the photoconductor 1,
The elastic body 12b is pressed against the photoconductor 1 so that the elastic body 12b is elastically deformed by the photoconductor 1. Cleaning unit 14 in which the cleaning roller 12 and the photoconductor 1 are in pressure contact with each other
The transfer residual toner T ₁ having both positive and negative polarities, which has reached, reaches the same polarity (negative polarity in this example) as the toner at the time of development while being in contact with the cleaning roller 12 and the surface of the photoconductor 1. It is frictionally charged.

Photoreceptor 1 after transfer of toner image onto transfer paper 16
Transfer residual toner T on₁Is pressed against the photoconductor 1.
Is collected by the rotating cleaning roller 12 from the
To the core member 12a of the cleaning roller 12 when collecting
Was frictionally charged between the roller 12 and the photoconductor 1.
Toner polarity opposite to charging polarity, positive voltage in this example, example
For example, the voltage of + 200V is the voltage power supply E._FourApplied by
You. Therefore, after passing through the transfer section 8, the photosensitive member 1 and the cleaning
Transfer residual toner T frictionally charged between the rollers 12
₁Is the cleaning roller 1 to which a positive voltage is applied.
2 is electrostatically attracted to the surface of
It adheres to the surface and is 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 zero or -50V due to the influence of the transfer roller 7 to which a positive voltage is applied, but a voltage of + 200V is applied. a cleaning roller 12 which is, by 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 electrostatically attracted to the surface of the cleaning roller 12 To be As a result, the surface of the photoconductor 1 is cleaned.

As described above, the cleaning roller 12 and the photosensitive member 1 are not transferred to each other, and the transfer residual toner T on the photosensitive member 1 is transferred to the cleaning roller 12.
_1, so that an electric field can be sucked electrostatically to the surface of the cleaning roller 12 is formed, (in this example the positive polarity) opposite polarity to the charging polarity of the toner during development voltage 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 . 2 through 10, the residual toner T ₁ of the the photosensitive member 1 is collected by the cleaning roller 12, and then allowed to reattach the collected toner T ₂ as described later on the surface of the photosensitive member 1, a developing device which 4 is an explanatory diagram showing an example of the operation of collecting the toner image on the transfer paper 1 in FIG.
6 is a schematic diagram showing a state in which the transfer residual toner T ₁ is transferred to _No. 6 and is collected on the surface of the cleaning roller 12. FIG.

In the drawings, the toner on the photosensitive member 1 or the cleaning roller 12 is schematically shown in an enlarged manner. Further, in FIGS. 2 to 10, the charging roller 2, the developing roller 5, and the transfer roller 7 are shown. And cleaning roller 12
The symbols + and-attached to indicate the positive and negative polarities of the voltage applied to them. FIG. 1
In the above, + and-signs attached to the toner indicate the charging polarity of the toner.

As shown in FIG. 2, the surface portion of the photoconductor 1 cleaned by the cleaning roller 12 is subjected to the charge removal action by the charge removal 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, and the above-mentioned 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 one sheet of 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. 2, this image forming area is denoted by reference numeral X1, and the tip of the photosensitive member in the rotational direction is denoted by reference numeral Y1. Similarly, in FIG. 3, a symbol Z1 is attached to the rear end of the image forming area X1 in the photoconductor rotating direction.

At a time point slightly before the time point shown in FIG. 2, when the leading edge Y1 of the image forming area X1 reaches the cleaning roller 12, the operation of collecting the transfer residual toner T ₁ on the cleaning roller 12 is started. In the illustrated example, the transfer residual toner collecting operation is continued until the rear end Z1 of the image forming area X1 reaches the cleaning roller 12 as shown in FIG.

Here, as described above, the cleaning member composed of the cleaning roller 12 is rotated to electrostatically and temporarily remove the transfer residual toner T ₁ on the image carrier composed of the photoconductor 1 after the toner image is transferred. The cleaning member cleans the surface of the photoconductor 1, and then the cleaning member rotates and collects the collected toner T ₂ on a surface portion that does not affect the formation of the electrostatic latent image on the image carrier. Reattach electrostatically.

That is, as shown in FIG. 3, when the rear end Z1 of the image forming area X1 in the direction of rotation of the photosensitive member passes the charging roller 2, the charging roller 2 is separated from the surface of the photosensitive member 1 at this time (see FIG. 4). ). 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.

When the trailing edge Z1 of the image forming area passes the developing roller 5 of the developing device 4 as shown in FIG. 4, the switch S ₁ shown in FIG. ₁ is switched, and the developing roller 5 is turned to the voltage power source E ₂ . A voltage of positive polarity, for example, + 500V, which is opposite to the charging polarity of the toner, is applied to the developing roller 5 so that the toner does not adhere to the photosensitive member 1. Subsequently, as shown in FIG. 5, the rear end Z1 of the image forming area is formed.
When the sheet passes through the transfer portion 8, the voltage application to the transfer roller 7 is stopped at this time. At this time, in this example, the transfer roller 7
Separate from the photoconductor 1 (see FIG. 6).

As described above, FIG. 6 shows the state in which the collection of the transfer residual toner to the cleaning roller 12 has been completed. The rear end Z1 of the image forming area X1 shown in this figure is When passing through the cleaning roller 12, the switch S ₂ shown in FIG. 1 is switched, the cleaning roller 12 is connected to the power source E ₅ , and the core member 12 a of the cleaning roller 12 includes the photosensitive member 1 and the cleaning roller. A voltage of, for example, −3000 V, which has the same negative polarity as the charging polarity of the toner frictionally charged with the toner 12, is applied.

[0040] In the image forming apparatus illustrated with respect to time of the recovery of the cleaning roller 12 of the transfer residual toner T ₁ of the the photosensitive member 1, during reattachment of the photosensitive member 1 of the recovery toner T ₂ of the on the cleaning roller 12 is , The rotation direction of the cleaning roller 12 is switched, and as shown in FIG.
The cleaning roller 12 is rotationally driven in the clockwise direction (arrow b direction) in the figure. The surface of the cleaning roller 12 and the surface of the photoconductor 1 rotate in opposite directions at the pressure contact portion between the two, so that the cleaning roller 12 rotates.

In this way, the cleaning roller 12
As shown in FIG. 7, the toner T ₂ on the upper portion of the toner T
It is reattached and returned to the non-image forming area W behind the rear end Z1 in the rotation direction of the photoconductor 1. By applying the above-mentioned voltage of −3000 V to the cleaning roller 12, the cleaning roller 12 and the rear end Z of the image forming area are applied.
Since an electric field in the direction in which the toner on the cleaning roller 12 is discharged toward the photoconductor 1 is formed between the photoconductor 1 and the non-image forming area W on the photoconductor surface on the rear side in the rotation direction of the photoconductor 1. However, due to this electric field, the toner is electrostatically transferred from the cleaning roller 12 to the photoconductor 1.

As shown in FIG. 8, 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. As shown in FIG. 9, the developing device 4 is reached. At this time, as described above, since the positive polarity voltage opposite to the charging polarity of the toner at the time of development is applied to the developing roller 5, the negative polarity toner T ₃ redeposited on the photoconductor 1 is applied. Is
It electrostatically moves to the developing roller 5 side and is collected in the developer in the developing device. In this way, the toner redeposited on the surface of the image carrier composed of the photoconductor 1 is developed by the developing device 4.
Electrostatically, the collected toner is reused in the developing device 4. With this configuration, waste toner can be eliminated, and it is not necessary to provide a toner transport 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 X2 shown in FIG. 8 and FIG. 9 is continuously subjected to the static elimination action by the static elimination lamp 13, and the leading end Y2 of the photoconductor rotating direction is moved to the charging roller 2,
The charging roller 2 comes into contact with the surface of the photoconductor 1 to negatively charge the next image forming area X2, and an electrostatic latent image is formed on the next image forming area X2 in exactly the same manner as described above. This is visualized as a toner image in the developing device 4 as shown in FIG. At this time, the developing roller 5
A negative voltage is applied to the tip of the image forming area Y
When 2 reaches the transfer portion 8, the transfer roller 7 is brought into pressure contact with the photosensitive member 1, the leading edge of the next transfer paper 16a reaches the transfer portion 8, and the toner image formed in the next image forming area X2 is transferred. It is transferred to the transfer paper 16a. The transfer residual toner at this time is collected by the cleaning roller 12 as described above, and the above-mentioned operation is repeated. When the leading edge Y2 of the image forming area before the electrostatic latent image is formed reaches the cleaning roller 12, a positive voltage is applied to the cleaning roller 12 again, and the roller 12 moves counterclockwise. It rotates (Fig. 8). In this way, the image forming operation is repeated a predetermined number of times.

As described above, the toner collected by the cleaning roller 12 reattaches to the non-image forming area W on the photoconductor 1, so that the reattached toner T ₃ causes electrostatic discharge during the image forming operation described above. Not only the latent image, but also the electrostatic latent image formed next is not affected.

When a corona discharger separated from the photosensitive member 1 is used as the charging device, when the re-adhered toner T ₃ passes through this discharger, the surface of the photosensitive member carrying the toner T ₃ is
For example, it may be configured to be charged to the same polarity as the toner charging polarity of −850 V. In this case, when the re-adhered toner T ₃ is collected by the developing roller 5, the voltage applied to this roller 5 is The toner T ₃ can be electrostatically collected by the developing roller 5 even if it is kept at −600 V as it is. When the charging device including the corona discharger is used, the contacting / separating operation of the charging device with respect to the photoconductor 1 is also unnecessary.

The above is a basic configuration example of the image forming apparatus and its operation.

Here, as shown in FIG. 1, in the casing 17 of the cleaning device 18, as described above, the transfer residual toner T ₁ is transferred from the image carrier composed of the photoconductor 1 to the cleaning member composed of the cleaning roller 12. When the toner to be collected is collected, the collected toner is dammed to the cleaning member, and the damming member 21 is provided to store the toner to be returned to the image carrier when the toner is reattached for returning the toner from the cleaning member to the image carrier. There is.

The dam member 21 of this embodiment is composed of a roller member extending parallel to the cleaning roller 12, and has a rigid core member 21a and an elastic member 21b concentrically fixed to the core member 21a. The elastic body 21b is pressed against the peripheral surface of the cleaning roller 12 over the entire length thereof. Further, in order to prevent the damming member 21 from rotating, each end portion of the core member 21a has the cleaning device 1
8 is fixed to the front and rear side walls of the casing 17.

The tip Y1 of the image forming area X1 shown in FIG.
When the toner passes through the cleaning roller 12, the transfer residual toner T ₁ is started to be collected. However, the toner T ₂ collected by the cleaning roller 12 is generated by the cleaning roller 12 continuing to rotate.
3 is conveyed while being carried on the peripheral surface facing upward, is carried to a wedge-shaped portion 23 formed by the cleaning roller 12 and the dam member 21, and is dammed by the wedge-shaped portion 23, as shown in FIGS. Cleaning roller 1
The toner T 2 on the toner ₂ is scraped off by the peripheral surface of the dam member 21 and dammed, and the collected toner T ₂ is collected on the wedge-shaped portion 23.
Are stored as shown in FIGS. 4 to 6. Therefore, the cleaning roller 1 that has passed through the dam member 21
No toner substantially adheres to the peripheral surface portion 2 of the cleaning roller 12, that is, the peripheral surface portion of the cleaning roller 12 facing downward in FIG.

FIG. 6 shows a state in which the rear end Z1 of the image forming area X1 reaches the cleaning roller 12 and the collection of the transfer residual toner is completed, as described above.
In this state, the maximum amount of collected toner is stored in the wedge-shaped portion 23, and at this time, the collected toner T ₂ is collected on the peripheral surface portion of the cleaning roller 12 facing upward from the wedge-shaped portion 23 to the photoconductor 1. It is attached.

After the recovery of the transfer residual toner from the photosensitive member 1 to the cleaning roller 12 is completed, the rotation direction of the cleaning roller 12 is switched as described above, and the roller 12 is moved in the direction of arrow b as shown in FIG. Rotate. At this time, the collected toner accumulated in the wedge-shaped portion 23 and the collected toner on the cleaning roller are carried in the rotation direction of the cleaning roller 12 and electrostatically adhere to the non-image forming area W on the photoconductor 1. As described above, the attached toner T ₃ passes under the static elimination lamp 13 as shown in FIG. 8 and is electrostatically collected by the developing device 4 as shown in FIG. 9.

In the conventional image forming apparatus of this type, the transfer residual toner T ₁ is uniformly attached to the peripheral surface of the cleaning roller 12 without rotating the cleaning roller 12 without using the damming member 21. The toner was being collected. That is, the collected toner is uniformly attached to the peripheral surface of the cleaning roller 12 without being blocked and accumulated at a predetermined portion on the peripheral surface of the cleaning roller 12.

According to this, when the toner adhered on the peripheral surface of the cleaning roller 12 is re-adhered to the photoconductor 1, all the toner cannot be returned to the photoconductor 1, and a part of the toner cannot be returned. Remains on the cleaning roller, the next time the transfer residual toner is collected from the photoconductor 1, the transfer residual toner must be collected on the surface of the cleaning roller to which the toner adheres, which improves the collection efficiency of the transfer residual toner. There is a problem that the toner image is deteriorated and the toner image is stained.

On the other hand, in the image forming apparatus of this embodiment, the damming member 21 damms the collected toner on the cleaning roller 12 and scrapes the toner once from the cleaning roller 12, so that the toner passing through the damming member 21 is blocked. The transfer residual toner T ₁ on the photoconductor 1 can be collected on the surface of the cleaning roller on which the toner does not adhere. Thus, when collecting the residual toner T ₁ of the the photosensitive member 1 to the cleaning roller 12, which one or more times, for example even if a plurality of rotating, the cleaning roller 12
Can always efficiently collect the transfer residual toner T ₁ on the surface on which the toner is not substantially attached. If the transfer residual toner in one image forming area is collected while the cleaning roller 12 is rotated once or more, the collecting efficiency can be further improved.

In the conventional image forming apparatus, when the cleaning roller 12 is rotated once or more to collect the transfer residual toner, a large amount of toner adheres after the collecting operation is completed for one rotation of the cleaning roller. The transfer residual toner on the photoconductor is collected on the surface of the cleaning roller, and the collection efficiency is significantly reduced. In the image forming apparatus of this example, as described above, even if the cleaning roller 12 is rotated a plurality of times during one toner collecting operation, the transfer residual toner can always be collected on the surface of the cleaning roller having no toner adhesion, and the collecting efficiency thereof can be improved. Can be increased.

Further, by adopting a structure in which the collected toner is blocked and collected on the cleaning roller, the amount of the collected toner held on the cleaning roller (accommodation amount)
Can be increased. As a result, as described below, it is possible to increase the image forming speed when the image forming operation is continuously performed a plurality of times.

In the embodiment described above, after the trailing edge Z1 of the image forming area X1 shown in FIG. 3 in the direction of rotation of the photosensitive member has passed the charging roller 2, as shown in FIG.
Are separated from the photoconductor 1. Then, the leading edge Y of the next image forming area X2 shown in FIG.
2 reaches the facing portion of the charging roller 2, the area X2
The charging roller 2 is in contact with the photoconductor 1 in order to charge (see FIG. 9). By the separating operation of the charging roller 2, the re-adhesion toner T on the photoconductor 1 is
₄ (FIG. 8) is allowed to pass through the part of the charging roller 2.

In the image forming apparatus described with reference to FIGS. 2 to 10, the transfer residual toner in each image forming area X1, X2 ... Is collected by the cleaning roller 12, and each collected toner is collected in each image forming area. It was reattached to each non-image forming area W located on the rear end side in the rotation direction of the photoconductor. For each image forming operation, the collection of the transfer residual toner and the reattachment of the collected toner are repeated.

On the other hand, when the image forming operation is continuously performed a plurality of times, each transfer residual toner generated in each operation can be continuously collected by the cleaning member and can be collectively held. Then, after the transfer residual toner is collected a predetermined number of times, the transfer residual toner is collectively attached to the non-image forming area of the photoconductor 1.

For example, in FIGS. 11 and 12, the image forming area X1 of the first image forming operation is the first image forming area and the subsequent image forming area X2 is the second image forming area. The image forming area Xn (FIG. 12) of the image forming operation is referred to as an nth image forming area, and after the transfer residual toner in the first image forming area X1 is collected by the cleaning roller 12, the collected toner is transferred to the photosensitive member. The transfer residual toner in the second image forming area X2 is continuously collected by the cleaning roller 12 without re-adhesion of the second image forming area X2.
Until the transfer residual toner in 2) is collected, all the transfer residual toners in the n image forming areas are completely cleaned by the cleaning roller 12.
To collect. Then, the collected toners are collectively reattached to the photoconductor 1 and returned. The toner is returned to the non-image forming area Wn on the upstream side in the rotation direction of the photoconductor 1 with respect to the rear end Zn of the nth image forming area Xn shown in FIG. The reference numeral T ₃ is the re-adhesion toner for n image forming areas. The redeposited toner T ₃ is electrostatically collected on the developing device 4 side as in the above-described example.

In the case of this example, the nth image forming area Xn
Only when the toner T ₃ redeposited to the non-image forming area Wn (FIG. 12) on the upstream side passes through the portion of the charging roller 2, the roller 2 may be separated from the photoconductor 1, and for example, As shown in FIG. 11, the first image forming area X1 and the second image forming area X1
When the non-image forming area W between the image forming area X2 and the charging roller 2 passes through the charging roller 2, the roller is kept in contact with the photoconductor 1 and the negative voltage is still applied thereto.
The same applies to the transfer roller 7. Further, only when the re-adhered toner T ₃ shown in FIG. 12 is collected on the developing roller 5, a positive voltage is applied to the developing roller 5, and for example, the first image forming area X1 and the second image forming area X2 are applied. When the non-image forming region W between the developing rollers 5 passes the developing roller 5, the negative voltage may be applied to the developing roller 5.
The same applies to the photosensitive member surface portion between other image forming areas adjacent to each other.

When the recovery of the transfer residual toner and the re-adhesion operation to the photoconductor 1 are performed at the timings shown in FIGS. 11 and 12, the non-image forming area W between the image forming areas is extremely small. It is possible to eliminate this non-image forming area W. However, since the re-adhesive toner is carried in the non-image forming area Wn behind the nth image forming area Xn, the non-image forming area in this case has the same size as in the case of FIGS. 2 to 10.

As described above, since the non-image forming area W between the image forming areas can be made small, as shown in FIG.
Transfer paper 1 onto which the toner image in the first image forming area X1 is transferred
6 and the next transfer paper 16a to which the toner image in the second image forming area X2 is transferred can be narrowed, and as a result,
It is possible to increase the image forming speed when the image forming operation is continuously performed plural times. As the number of times n until the operation of reattaching the toner to the photoconductor 1 is increased, the number of operations of reattaching the toner from the cleaning roller 12 to the photoconductor 1 decreases and the image forming speed can be increased. it can.

As described above, when the image forming operation is continuously performed n times and the transfer residual toner in the image forming area for the n times is collected by the cleaning roller 12, the image forming apparatus of this example has Cleaning roller 12
Since the collected toner above can be dammed by the damming member 21, the amount of toner that can be held on the cleaning roller 12 increases, and the number of n can be increased. This makes it possible to remarkably increase the image forming speed during the continuous image forming operation.

In the examples shown in FIGS. 1 to 12, the toner collected from the photoconductor 1 is replaced with the cleaning roller 12
It is configured to be carried on the upper side surface facing upward, and to be stored in the wedge-shaped portion 23 which is also facing upward and is opened.
The toner accumulated here does not fall downward even if the amount thereof increases. Also, when reattaching the toner to the photoconductor 1, the rotation direction of the cleaning roller 12 is switched and the toner is carried while being carried on the upper side surface of the cleaning roller 12, so that the toner is collectively exposed in a short time. It can be reattached to the body 1 and returned.

Further, if the damming member 21 is rotated, the damming member 21 carries the toner on this peripheral surface, which may impair the damming action of the collected toner. From this point of view, it is preferable that the dam member 21 not rotate.

The dam member may be a columnar or cylindrical member having a perfect circumferential surface like the dam member 21 shown in FIG. 1, but it does not have a perfect circumferential surface, for example, a fan shape. It may be one. When the dam member has a columnar shape or a cylindrical shape having a complete circumferential surface, or a fan shape, the dam position member is changed by periodically changing the rotation position of the dam member and the contact position with the cleaning roller 12. It is possible to prevent wear and deterioration at the same place 21.

Further, as in the example shown in FIG. 13, a blade-shaped damming member 31 made of an elastic material such as rubber is used.
May be used. In the case of this example, when the transfer residual toner is collected, the surface of the cleaning roller 12 is
Is rotated in the direction of arrow b so as to be opposite to the moving direction of the surface of the photoconductor 1 at the contact portion with. The collected toner T ₂ is dammed and stored in a wedge-shaped part formed between the damming member 31 whose tip edge portion is in contact with the cleaning roller 12 and the cleaning roller 12. After the transfer residual toner is collected, the cleaning roller 1
The rotation direction of 2 is switched, and the cleaning roller 12 is rotationally driven in the direction opposite to the arrow b direction. Along with this,
The accumulated toner is reattached to the photoconductor 1 together with the toner on the cleaning roller 12 and returned to the photoconductor.

In this example, when the transfer residual toner is collected, the dam member 31 is brought into contact with the cleaning roller 12 as shown by the solid line, and when the collected toner is reattached,
If the dam member 31 is separated from the cleaning roller 12 by a damming member operating means (not shown), such as a solenoid or a motor, as shown by an imaginary line, when the toner is re-adhered to the photoconductor 1, the cleaning roller 12 is removed. Even if is rotated in the same direction as when the transfer residual toner is collected, the collected toner can be reattached to the photoconductor 1 without any trouble. The same thing can be said even if a configuration is adopted in which the contact force of the damming member 31 with respect to the cleaning roller 12 is made weaker when the collected toner is reattached than when the transfer residual toner is collected.

When the toner is redeposited on the photosensitive member 1, as shown in FIG.
If the damming member 31 shown in FIG. 6 is still in contact with the cleaning roller 12, or if the contact force is not weakened more than when the transfer residual toner is collected, the cleaning roller 12 is moved in the direction of arrow b. When the toner is re-adhered to the photoconductor 1 by rotating it to the position of 1, the collected toner T ₂ cannot pass through the portion between the dam member 31 and the cleaning roller 12, and the toner cannot be returned to the photoconductor 1. . Therefore, when reattaching the collected toner, it is necessary to rotate the cleaning roller 12 in the direction opposite to the arrow b direction.

On the other hand, if the dam member 31 is separated from the cleaning roller 12 or the contact force of the dam member 31 with respect to the cleaning roller 12 is weakened when the collected toner is reattached, the collected toner T ₂ is removed. The passage at the above-mentioned site becomes possible. Thus, when the collected toner is reattached, the cleaning roller 1
Since it is possible to adopt a configuration in which 2 is rotated in the same direction as when the transfer residual toner is collected, it is not necessary to switch the rotation direction of the cleaning roller, so that the cleaning roller drive control system can be simplified. The configuration in which the damming member 31 is brought into contact with and separated from the cleaning roller 12 can also be adopted in the example shown in FIG. That is, when the transfer residual toner is reattached, the dam member 21 is separated from the cleaning roller 12 by the dam member operating means (not shown), or the dam member 21.
That is, the contact force with respect to the cleaning roller 12 is weakened.

As described above, the dam member is the photosensitive member 1.
When the transfer residual toner is collected from the image carrier composed of the image carrier to the cleaning member composed of the cleaning roller 12, it is pressed against the cleaning member, and the contact force against the cleaning member is weakened when the toner is reattached from the cleaning member to the image carrier. Alternatively, by providing a damming member operating means for actuating the damming member so as to be separated from the cleaning member, it becomes possible to simplify the rotation control mode of the cleaning member.

A blade-shaped dam member 31 made of an elastic material such as rubber may be arranged at the position shown in FIG. 14 and the dam member 31 may be brought into contact with the cleaning roller 12. When the dam member 31 is arranged at such a position, the cleaning roller 12 is rotated in the direction of arrow a when collecting the transfer residual toner. By rotating the cleaning roller 12 in this direction, the collected toner T ₂ is dammed and accumulated by the wedge-shaped portion opened upward between the damming member 31 and the cleaning roller 12.

When the damming member 31 is kept in pressure contact with the cleaning roller 12 at all times, when the collected toner is reattached to the photoconductor 1, the cleaning roller 1
The rotation direction of No. 2 is switched, the roller is rotated in the direction opposite to the arrow a direction, and the collected collected toner T ₂ is conveyed on the cleaning roller 12 to be reattached on the photoconductor 1.

Also in this case, if the damming member operating means is provided and the damming member 31 is brought into contact with and separated from the cleaning roller 12, the cleaning roller is always rotated in the same direction (direction of arrow a). The transfer residual toner can be collected and the toner can be reattached to the photoconductor 1.

By the way, in the example shown in FIGS. 1 and 14, the dam members 21 and 31 are the cleaning roller 1
Of the peripheral surface of the cleaning member consisting of 2, the peripheral surface of the cleaning member composed of the photosensitive member 1 is opposed to the peripheral surface of the cleaning member facing the surface of the image carrier. The damming members 21 and 31 are provided at positions apart from the contact portion (cleaning portion 14) between the photoconductor 1 and the cleaning roller 12. Temporarily, dam members 21, 31
Is provided near the contact portion between the cleaning roller 12 and the photoconductor, the damming members 21, 3 are provided.
When the toner stopped by 1 scatters, the scattered toner may adhere to the photoconductor 1 to cause background stain on the image. The damming members 21 and 31 are shown in FIG.
As shown in FIG. 4, by providing the cleaning unit 14 at a position as far as possible from the cleaning unit 14, it is possible to prevent the occurrence of such background stains.

Here, each of the dam members 21 and 3 described above is used.
Basically, the voltage on the cleaning roller 12 may not be applied to the toner 1, but the toner on the cleaning roller 12 may be stopped by a mechanical scraping force. A voltage can also be applied to the damming member so that an electric field that electrostatically attracts the toner toward the damming member acts between the damming member and the cleaning roller.

For example, in FIG. 14, at the time of collecting the transfer residual toner, a voltage having a polarity opposite to the charging polarity of the toner at the time of development is applied to the blade-shaped damming member 31 by the power source E ₆ , which is a positive polarity in this example. Apply voltage. If such a configuration is adopted, the negative polarity toner on the cleaning roller 12 can be positively attracted electrostatically to the damming member 31 side, and the effect of damming and accumulating the toner can be enhanced. In this example, since a voltage is applied to the dam member 31, it is preferable that the dam member be made of, for example, a medium resistance material. Also in the example shown in FIG. 13, the same voltage can be applied to the dam member 31 and the same effect can be obtained.

Also in the example shown in FIG. 1, it is possible to adopt a structure in which a similar voltage is applied to the damming member 21 made of a roller-shaped member. At that time, the dam member 21 shown in FIG.
The core member 21a is made of a conductor, the elastic body 21b is made of a medium resistance material, and a voltage is applied to the core member 21a. That is, the core member 21a has a power source E ₆ when the toner is collected from the photoconductor 1 to the cleaning roller 12.
, A voltage having a polarity opposite to the charging polarity of the toner at the time of development, that is, a positive polarity voltage in this example, is applied.
The same effect as that of the example shown in FIG. 14 can be obtained.

At the time of collecting the transfer residual toner, as described above, for example, +20 is applied to the cleaning roller 12.
A voltage of 0V is applied. On the other hand, by applying a voltage of the same polarity as that of the voltage applied to the cleaning roller 12 to the damming members 21 and 31, and a voltage higher than this, for example, + 600V. The collected toner can be effectively and electrostatically attracted to the damming members 21 and 31.

In the above example, the power source E ₆ shown in FIGS. 1 and 14 electrostatically attracts the toner from the cleaning member to the damming member when the transfer residual toner is collected from the image carrier to the cleaning member. The voltage applying means is configured to apply a voltage to the damming member so that the electric field in the direction is formed between the cleaning member and the damming member.

At the time of applying the above-mentioned voltage at the time of collecting the transfer residual toner, or instead of reapplying the toner from the cleaning roller 12 to the photosensitive member 1, at the time of developing the damming members 21, 31. A voltage having the same polarity as the charging polarity of the toner may be applied.

That is, at the time of re-adhesion of toner, FIG. 1 and FIG.
By switching the switch S ₃ shown in FIG.
The core member 21a of one or damming member 21 connected to the upper power supply E _7, this power source E _7, damming member 21,
A negative voltage is applied to 31. By this application, an electric field is formed between the damming members 21, 31 and the cleaning roller 12 so that the toner dammed by the wedge-shaped portion 23 and accumulated therein is electrostatically attracted toward the cleaning roller 12. By the action of such an electric field, it is possible to prevent the toner from remaining and staying on the damming members 21, 31 side, particularly on the wedge-shaped portion 23 side.

As described above, at the time of reattachment of the collected toner, the cleaning roller 12 is powered by the power source E ₅ .
A voltage of 3000 V is applied. When such a voltage is applied, when a voltage of, for example, -3400 V is applied to the damming members 21 and 31 by the power supply E ₇ , the cleaning roller 12 side. The collected toner can be positively attracted electrostatically. As shown in FIG. 13, the above configuration can be similarly applied to a configuration in which the damming member 31 is brought into contact with or separated from the cleaning roller 12 at the time of re-adhesion of toner, or the contact force thereof is weakened.

In the above-mentioned example, when the toner is reattached from the cleaning member to the image carrier by the power source E ₇ , the electric field in the direction in which the toner is transferred from the damming member to the cleaning member is generated between the cleaning member and the damming member. The voltage applying means is configured to apply a voltage to the damming member so as to be formed.

Regarding the polarity of the voltage applied to the damming member and its switching timing, see FIGS.
It can be well understood from the plus (+) and minus (-) signs attached to the dam member 21.

In each of the embodiments described so far, the cleaning roller 12 is used as the cleaning member. However, an endless belt wound around a plurality of pulleys may be used as the cleaning member. good.

For example, as shown in FIGS. 15 and 16, an endless belt 32 wound around a pair of pulleys 25 and 26 is used as a cleaning member. Hereinafter, the endless belt shown in FIGS. 15 and 16 is referred to as a “cleaning belt”, and in this example, the belt portion wound around the pulley 26 is in contact with the photoconductor 1, and the contacted portion is the cleaning portion 14. ing. The cleaning belt may be a belt that is wound around three or more pulleys instead of a pair of pulleys, and may be any belt that is wound around a plurality of pulleys.

The leading edge portion of the blade-shaped damming member 31 is in contact with the cleaning belt 32, and the transfer residual toner T ₁ on the photoconductor ₁ is removed by the cleaning belt 32.
When the cleaning belt 32 is to be collected, the surface of the cleaning belt 32 is rotationally driven in a direction in which it moves in the same direction as the moving direction of the surface of the photoconductor 1 at the portion facing the photoconductor (direction of arrow a). At this time, the toner T ₂ collected on the cleaning belt 32 is dammed by the damming member 31.
It is accumulated in a wedge-shaped portion formed between the dam member 31 and the cleaning belt 32. Next, when the collected toner is reattached from the cleaning belt 21 to the photoconductor 1, the surface of the cleaning belt 32 faces the photoconductor 1 as shown in FIG.
Is rotated in the direction of the arrow b so as to be opposite to the moving direction of the surface of the toner, and the collected toner T ₂ accumulated is returned onto the photoconductor 1. Then, the returned toner T ₃ is collected by the photoconductor 1
As described above, it is carried over and collected by the developing device 4 shown in FIG.

When such a cleaning belt 32 is used as the cleaning member, the amount (holding amount) of the collected toner on the belt can be further increased. Since the distance on the peripheral surface of the belt from the cleaning unit 14 to the dam member 31 in the a direction is long, the amount of collected toner held on the belt can be increased. As a result, without re-adhesion of toner,
Transfer residual toner in a large number of image forming areas can be continuously collected by the cleaning member. That is, the number of times n described above with reference to FIGS. 11 and 12 can be increased to further increase the image forming speed during image formation.

In the example shown in FIG. 15, the dam member 31 is in contact with the belt portion wound around the pulley 25 in the outer peripheral portion of the cleaning belt 32. When contacted with a portion other than the belt portion wound around the pulleys 25 and 26 as shown in FIG. 3, the belt portion bends due to the pressing force of the dam member 31, and the portion escapes toward the inner side of the belt, and the dam member The contact force of the toner may weaken, and the damming action of the toner may be impaired. The damming function may deteriorate.

Therefore, as shown in FIG. 17 and FIG.
The cleaning member is composed of an endless belt 32 wound around a plurality of pulleys 25 and 26, and is a dam member 31.
However, it is advantageous to provide the backup member 27 so as to come into contact with the back surface portion on the opposite side of the abutting belt portion surface when the belt portion in the free state not wound around the pulleys 25 and 26 is abutted. Backup member 2
7 prevents escape of the belt portion in contact with the dam member 31. By providing such a backup member 27, even if the dam member 31 is provided at a position removed from the pulleys 25 and 26, the dam member 31 is in contact with, for example, a belt portion of the two pulleys, which is wound around the pulley 25. It is possible to obtain a contact force similar to the contact force in the case of causing it, and it is possible to prevent deterioration of the damming performance of the collected toner. Note that, as shown in FIG. 18, even when the collected toner T ₂ is reattached to the photoconductor 1, the backup member 27 prevents the escape of the belt portion.

Also in the example shown in FIGS. 15 to 18,
A configuration in which a voltage is applied to the damming member 31 at the time of collecting the transfer residual toner, or a configuration in which the voltage is applied as described above both at the time of collecting the transfer residual toner and at the time of re-adhering the collected toner, and cleaning the damming member. It is possible to adopt a configuration in which the member is brought into contact with or separated from the member, or a pressure is weakened, and further, a dam member is brought into contact with a peripheral surface portion of the cleaning member on the side opposite to the image carrier.

The present invention can be applied to an image forming apparatus using not only a drum-shaped image carrier but also an endless belt-shaped one, and an intermediate transfer member as a recording medium. It can also be applied to an image forming apparatus of a type in which a toner image is transferred onto an intermediate transfer member and then transferred onto a transfer material. 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 is also applicable to a so-called positive / positive developing type image forming apparatus in which toner is attached to the electrostatic latent image for development.

[0095]

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,
Further, in the image forming apparatus that electrostatically collects the re-adhered toner to the developing device, while holding the collected toner on the cleaning member by the damming member, the toner is accumulated and re-adhered collectively to the image carrier. Therefore, the transfer residual toner on the image bearing member can be collected by the surface of the cleaning member substantially free of toner, and the collection efficiency can be improved.

According to the image forming apparatus of the second aspect,
Since it is possible to adopt a configuration in which the cleaning member is rotated in the same direction when the transfer residual toner is collected and when the collected toner is reattached, the drive control method of the cleaning member can be simplified.

According to the image forming apparatus of claim 3,
When the toner is scattered from the contact portion between the damming member and the cleaning member, it is possible to make it difficult for the scattered toner to adhere to the surface of the image carrier, and it is possible to prevent the occurrence of scumming due to the adhesion.

According to the image forming apparatus of claim 4,
At the time of collecting the transfer residual toner, the collected toner can be positively electrostatically attracted to the damming member side, and the effect of damming and accumulating the toner can be enhanced.

According to the image forming apparatus of the fifth aspect,
It is possible to prevent the toner from remaining and staying on the damming member side when the toner is reattached to the image carrier.

According to the image forming apparatus of claim 6,
It is possible to increase the amount of toner held on the cleaning member when the transfer residual toner is collected.

According to the image forming apparatus of claim 7,
Even if the damming member is provided so as to come into contact with the belt portion removed from the pulley, it is possible to prevent the damming force of the damming member on the belt from being weakened or prevent the damming member from coming into contact with the belt portion. It is possible to carry out the function of stopping and accumulating without any hindrance.

[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 shows a relative positional relationship between a charging roller, a developing roller, a transfer roller, a cleaning roller, and a damming member, and a photoconductor, and illustrates how the transfer residual toner on the photoconductor is collected by the cleaning roller. FIG.

FIG. 3 is an explanatory diagram showing a state when the rear end of the image forming area reaches a portion facing the charging roller.

FIG. 4 is an explanatory diagram showing a state when the rear end of the image forming area reaches a portion facing the developing roller.

FIG. 5 is an explanatory diagram showing a state when the rear end of the image forming area reaches a portion facing the transfer roller.

FIG. 6 is an explanatory diagram illustrating a state when a rear end of an image forming area reaches a portion facing a cleaning roller.

FIG. 7 is an explanatory diagram showing a state where toner collected on a cleaning roller is reattached to a photoconductor.

FIG. 8 is an explanatory diagram illustrating a state in which the re-adhered toner on the photosensitive member is transported toward the developing device.

FIG. 9 is an explanatory diagram illustrating a state in which the re-adhered toner on the photosensitive member is collected by the developing device.

FIG. 10 is an explanatory diagram showing a state when the leading edge of the next image forming area reaches a portion facing the transfer roller.

FIG. 11 is an explanatory diagram showing a state in which a plurality of image forming operations are continuously performed without reattaching the toner collected by the cleaning roller to the photoconductor.

FIG. 12 is an explanatory diagram showing a state after the toner collected by the cleaning roller is reattached to the photoconductor after the image forming operation is continuously performed a plurality of times.

FIG. 13 is a schematic view showing a configuration of an embodiment in which a blade-shaped damming member is brought into contact with and separated from a cleaning roller.

FIG. 14 is a schematic diagram showing the configuration of an embodiment in which a voltage is applied to a blade-shaped damming member.

FIG. 15 is a schematic view showing a configuration of an embodiment example in which a cleaning belt is used as a cleaning member.

FIG. 16 is a schematic view showing a state where the collected toner on the cleaning belt is returned toward the photoconductor in the embodiment shown in FIG.

FIG. 17 is a schematic view showing a configuration of an embodiment example in which a backup member is provided on the back side portion of the cleaning belt with which the damming member abuts.

FIG. 18 is a schematic view showing a state where the collected toner on the cleaning belt is returned toward the photoconductor in the embodiment shown in FIG.

[Explanation of symbols]

 4 developing device 21 damming member 31 damming member 25 pulley 26 pulley 27 backup member 32 endless belt

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

Claims (7)

[Claims] 1. An image carrier that is driven to rotate, a latent image forming unit that forms an electrostatic latent image on the carrier, and a developing device that visualizes the electrostatic latent image as a toner image. A transfer device that transfers the toner image on the image carrier to the recording medium, and while rotating, electrostatically temporarily collects the transfer residual toner on the image carrier after the toner image transfer, and then the recovered toner And a cleaning member for electrostatically redepositing on the surface portion of the image carrier that does not affect the formation of an electrostatic latent image, and the toner redeposited on the surface of the image carrier is electrostatically charged to the developing device. In an image forming apparatus that collects toner, the toner collected on the cleaning member is dammed when the transfer residual toner is collected from the image carrier to the cleaning member, and the image carrier is carried on when the toner is re-adhered from the cleaning member to the image carrier. Toner is collected for returning to the body An image forming apparatus characterized in that a writing damming member. 2. The damming member presses against the cleaning member when the transfer residual toner from the image carrier to the cleaning member is collected, and when the toner is re-adhered from the cleaning member to the image carrier, the contact force against the cleaning member is increased. The image forming apparatus according to claim 1, further comprising a damming member operating means that actuates the damming member so as to be weakened or separated from the cleaning member. 3. The image forming apparatus according to claim 1, wherein the damming member is arranged at a peripheral surface portion opposite to the cleaning member peripheral surface portion facing the image carrier surface. 4. An electric field in which the toner is electrostatically attracted from the cleaning member to the damming member is formed between the cleaning member and the damming member when the transfer residual toner is collected from the image carrier to the cleaning member. 4. The image forming apparatus according to claim 1, further comprising a voltage applying unit that applies a voltage to the damming member. 5. The damming member so that an electric field in a direction in which the toner is transferred from the damming member to the cleaning member is formed between the cleaning member and the damming member when the toner is re-adhered to the image carrier from the cleaning member. The image forming apparatus according to claim 1, further comprising a voltage applying unit that applies a voltage to the image forming apparatus. 6. The image forming apparatus according to claim 1, wherein the cleaning member is an endless belt wound around a plurality of pulleys. 7. The cleaning member is composed of an endless belt wound around a plurality of pulleys, and the damming member abuts on a belt portion in a free state not wound around the pulleys, and the abutting belt portion surface. 7. The image forming apparatus according to claim 1, wherein a backup member is provided so as to come into contact with the back surface portion on the opposite side of the above.