JPH09230750A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent base soil from occurring on an image, which is caused by transfer toner remaining on a photoreceptor when jam occurs, in an image forming device which recovers the residual transfer toner to a cleaning roller, sticks the recovered toner again to the photoreceptor, and recovers the restuck toner to a developing device. SOLUTION: The residual transfer toner T1 remaining in the area of the periphery of the photoreceptor 1 between a transfer part 8 and a cleaning part 14 when a jam has occurred is recovered to the cleaning roller 12 at the time of the restart of the image forming device. Then, it is restuck to the photoreceptor 1, and the restuck toner is recovered in the developing device 4.

Description

Detailed Description of the Invention

[0001]

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

[0002]

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

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

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

Therefore, as a second best measure, the transfer residual toner remaining on the surface of the image carrier after the transfer of the toner image is electrostatically adhered to the cleaning member and collected, and then this recovered toner is collected on the image carrier. A method of electrostatically reattaching, electrostatically collecting by a developing device, and reusing it has been proposed (for example, see Japanese Patent Publication No. 61-30274).
After the transfer of the toner image, the transfer residual toner remaining on the image carrier is electrostatically temporarily collected by the cleaning member, and then the collected toner is transferred to the next electrostatic latent image on the image carrier. Electrostatically redeposit on the surface part that does not affect the formation,
Further, the toner redeposited on the surface of the image carrier is electrostatically collected by the developing device. This eliminates the need for a dedicated means for transferring the collected toner to a waste toner tank or a developing device, thus reducing the cost of the image forming apparatus and reusing the toner. It can be lost. Further, when the transfer residual toner is collected by the cleaning member, the toner is triboelectrically charged with the image carrier, and the charging polarity of the toner is aligned with the charging polarity of the toner at the time of development. An image forming apparatus configured to efficiently and electrostatically collect is also proposed.

In this type of image forming apparatus, when a conveyance trouble of the recording medium, that is, a jam occurs during the image forming operation, the image forming operation is stopped so that the operator can remove the jammed recording medium. I have to.
Then, the image forming apparatus is restarted at the time of the jam processing, but in the conventional image forming apparatus of this type, the toner adhered on the image carrier or the cleaning member at the time of the jam is formed by the image forming operation. No particular consideration has been given to how to efficiently process and start the image forming operation when the apparatus is restarted. Therefore, it takes a long time until a predetermined image can be formed after the image forming apparatus is restarted, or the cleaning efficiency of the cleaning member is reduced when the image forming operation is performed. Also, when a jam occurs, a part of the toner adhered on the image carrier remains on the image carrier,
There was a risk of background stains on the image.

[0007]

SUMMARY OF THE INVENTION A first object of the present invention is to electrostatically collect transfer residual toner on a cleaning member, electrostatically redeposit the recovered toner on an image carrier, and then The residual transfer that was present on the image carrier when the recording medium was jammed was solved by solving the above-mentioned problems in the image forming apparatus in which the re-adhered toner is electrostatically collected by the developing device. When the image forming apparatus is subsequently restarted, the residual toner can be effectively collected by the developing device, so that a part of the residual transfer residual toner remains on the image carrier to prevent the occurrence of background stains on the image. An object of the present invention is to provide an image forming apparatus capable of preventing the above.

A second object of the present invention is to electrostatically collect the transfer residual toner on the cleaning member, electrostatically re-adhere the recovered toner to the image carrier, and then to re-adhere the re-adhered toner. By solving the above-mentioned problems in the image forming apparatus of the type that electrostatically collects by the developing device, the toner remaining on the cleaning member when the recording medium is jammed causes the image forming operation after the jam processing. An object of the present invention is to provide an image forming apparatus capable of preventing a decrease in cleaning efficiency of an image carrier when the above-mentioned procedure is performed.

A third object of the present invention is to electrostatically collect the transfer residual toner on the cleaning member, electrostatically re-adhere the recovered toner to the image carrier, and then to re-adhere the re-adhered toner. Even if a toner image is formed on the image bearing member when a jam occurs on the recording medium by solving the above-described problems in the image forming apparatus of the type that electrostatically collects by the developing device, When the image forming apparatus is restarted, the toner of the toner image is completely collected in the developing device in a short time, and the image forming apparatus that can reduce the time until the image formation is possible after the image forming apparatus is restarted is provided. To provide.

[0010]

In order to achieve the first object, the present invention comprises an image carrier which is rotationally driven, and latent image forming means for forming an electrostatic latent image on the carrier. 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 a recording medium, and a transfer residual toner on the image carrier after the toner image transfer is developed. The transfer residual toner is triboelectrically charged with the image bearing member so that the charging polarity at that time becomes uniform, and the transfer residual toner triboelectrically charged is electrostatically and temporarily collected. A cleaning member for electrostatically re-adhering the toner to the surface portion of the image carrier that does not affect the formation of the next electrostatic latent image, and developing the toner re-adhered to the surface of the image carrier. A state in which the device is electrostatically collected and the image forming operation is being executed. When jammed onto the recording medium,
In the image forming apparatus in which the image forming operation is stopped, transfer residual toner is present in the peripheral surface area of the image carrier on the downstream side of the transfer device and on the upstream side of the cleaning member with respect to the rotation direction of the image carrier. When a jam occurs on the recording medium while the image forming device is restarting,
While rotating the image carrier in the rotation direction during the image forming operation,
The cleaning member electrostatically collects the toner remaining on the surface of the image carrier at the time of occurrence of the jam, and then electrostatically redeposits the collected toner on the surface of the image carrier to develop the redeposited toner. An image forming apparatus is proposed in which the apparatus is provided with a control unit that executes a mode of electrostatically collecting (Claim 1).

In order to achieve the second object of the present invention, the image carrier which is rotationally driven, the latent image forming means for forming an electrostatic latent image on the carrier and the electrostatic latent image are formed. A developing device that visualizes 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 is transferred have the same charging polarity during development. As described above, the transfer residual toner is triboelectrically charged with the image carrier, and the frictionally charged transfer residual toner is electrostatically and temporarily collected. A cleaning member for electrostatically re-adhering to the surface portion that does not affect the formation of the next electrostatic latent image is provided, and the toner re-adhering to the surface of the image carrier is electrostatically charged in the developing device. While collecting the images, while the image forming operation is being performed, In the image forming apparatus in which the image forming operation is stopped when the image is generated, the trailing end of the image forming area on the image carrier in the rotation direction of the image carrier passes through the cleaning member, and the collected toner remains on the cleaning member. When a jam occurs on the recording medium in the state where the image forming apparatus is restarted after that, the residual toner collected on the cleaning member is removed from the image carrier while rotating the image carrier in the rotation direction during the image forming operation. An image forming apparatus is provided, which is provided with a control unit that electrostatically redeposits on the surface of the sheet and electrostatically collects the redeposited toner on the developing device (claim 2). .

In order to achieve the third object of the present invention, the image carrier which is rotationally driven, the latent image forming means for forming an electrostatic latent image on the carrier, and the electrostatic latent image are formed. A developing device that visualizes 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 is transferred have the same charging polarity during development. As described above, the transfer residual toner is triboelectrically charged with the image carrier, and the frictionally charged transfer residual toner is electrostatically and temporarily collected. A cleaning member for electrostatically re-adhering to the surface portion that does not affect the formation of the next electrostatic latent image is provided, and the toner re-adhering to the surface of the image carrier is electrostatically charged in the developing device. While collecting the images, while the image forming operation is being performed, In the image forming apparatus in which the image forming operation is stopped when the image is generated, before the tip of the toner image on the image carrier in the rotation direction of the image carrier reaches the transfer portion where the toner image is transferred by the transfer device. When the recording medium is jammed, when the image forming apparatus is restarted thereafter, the toner of the toner image is collected by the cleaning member while rotating the image carrier in the rotation direction during the image forming operation. Without the above, a control means is provided for executing a mode in which the toner of the toner image is passed through the cleaning member while being held on the image carrier and the toner is electrostatically collected by the developing device. An image forming apparatus is proposed (claim 3).

[0013]

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 to a negative (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
For example, it is charged to -850V. 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, an exposure scanning device (not shown) performs optical writing scanning using, 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 this example, the charging roller 2 and the exposure scanning device form a latent image forming unit that forms an electrostatic latent image on the image carrier made of the photoconductor 1.

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 form the main body of the developing device. Each of the developing casings 9 is provided and rotatably supported by the casing 9. 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.

In the developing device 4 illustrated here, a two-component developer D having a toner and a carrier is used, and the developer D is contained in the developing casing 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 during development is negative. A developing device using a one-component developer having no carrier may be employed.

The developing roller 5 is driven to rotate counterclockwise in the drawing, and the developer carried on the peripheral surface of the developing roller 5 is conveyed in the rotating direction of the developing roller 5, and the roller 5 is rotated.
The developer regulating member 15 oppositely arranged with a predetermined gap therebetween is scraped. 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 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 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 causes the photoconductor 1 to move. The toner image formed thereon is transferred onto the transfer paper 16. That is, the power source E _{3 is applied} to the transfer roller 7 so that
Positive (plus) polarity voltage opposite to the charge polarity of the above toner,
For example, a voltage of + 950V is applied, and at this time, the negative toner T on the photoconductor 1 is electrostatically attracted to the transfer paper 16 side and adheres 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 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 section 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 a core member 12a made of a rigid body, and a conductive or medium-resistance elastic body 12b fixed to the surface of the core member 12a. In the illustrated example, the core member 12a. Is made of a round shaft-shaped conductive metal, and the elastic body 12b is made of a foamed body formed in a cylindrical shape concentric with the core member 12a. The cleaning roller 12 is the cleaning case 1 shown in FIGS.
7, and each end of the core member 12a has side walls 17a and 17b at the front and rear of the cleaning case 17 (FIG. 15).
Each is rotatably supported by. 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 unit 6 to the transfer unit 8 is a 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 of the present embodiment, when recovering the residual toner T ₁ of the the photosensitive member 1, a clockwise direction in FIG. 1 (arrow a direction), i.e. in the counter direction with respect to the rotation direction of the photosensitive member 1 It is driven to rotate and rotates while rubbing against the surface of the photoconductor 1. The cleaning roller 12 is pressed against the photoconductor 1 so that the surface of the cleaning roller 12 is elastically deformed by the photoconductor 1.
As shown in FIG. 3, a nip area N is formed in this pressure contact portion. This nip area N becomes a cleaning area. Although the width of the nip area N in the circumferential direction of the photosensitive member is, for example, about 1 mm, the width of the nip area N is exaggerated in FIG.

In the nip region N, the transfer residual toner T ₁ having both positive and negative polarities becomes a toner having the same polarity (in this example, negative polarity) as the toner at the time of development while being in contact with the cleaning roller 12. It is frictionally charged. That is, the cleaning member including the cleaning roller 12 is arranged 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. The transfer residual toner is triboelectrically charged. The elastic body 12b of the cleaning roller 12 is composed of a charging series charging material capable of frictionally charging the toner to its original polarity, in this example, negative polarity.

Returning to FIG. 1, the transfer residual toner T ₁ on the photosensitive member 1 after the toner image is transferred onto the recording medium composed of the transfer paper 16
Is collected by a cleaning member composed of a cleaning roller 12 that rotates while being pressed against the photoconductor 1, and at the time of collection, the core member 12 of the cleaning roller 12 is collected.
A voltage having a polarity opposite to the charging polarity of the toner frictionally charged by the roller 12, that is, a positive voltage in this example, for example, +200 V, is applied to a by the voltage power source E ₄ .
Therefore, the residual toner after the transfer of the toner image, which has passed through the transfer portion 8, that is, the residual transfer toner T ₁ frictionally charged by the cleaning roller 12 is electrostatically applied to the surface of the cleaning roller 12 to which the positive voltage is applied. It is attracted, adheres to the surface of the roller 12, and is temporarily collected by this roller. As a result, the surface of the photoconductor 1 is cleaned. In this manner, the cleaning roller 12 rotating in contact with the photoconductor 1 electrostatically attracts the transfer residual toner T ₁ on the photoconductor ₁ to the surface of the cleaning roller 12 with the photoconductor _1. A voltage having a polarity (positive polarity in this example) opposite to the charging polarity of the toner during development is applied so that an electric field to be obtained is formed.

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 11, 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 in FIG. 3 among these drawings, the toner image on the photoconductor 1 is indicated by an arrow
6 is a schematic view showing a state in which the transfer residual toner T ₁ transferred onto the transfer paper 16 conveyed in the direction is collected on the surface of the cleaning roller 12. FIG. 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 of collecting the transfer residual toner T _{1 on} the second transfer roller 2 starts. In the illustrated example, the operation of collecting the transfer residual toner 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 the cleaning roller 12 has already been cleaned by the cleaning roller.

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.

[0032] 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).

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

Due to the electric field, as shown in FIG.
The toner T ₂ temporarily collected on the cleaning roller 12 is reattached to the non-image forming area W on the photoconductor 1 and returned. At this time, the cleaning roller 12 of this example is
The photoconductor 1 is rotationally driven in the forward direction (counterclockwise in FIG. 1). Toner T redeposited on the photoconductor 1
_As shown in FIG. 9, the photoconductor ₃ passes under the charge removing roller 13 and the charging roller 2 separated from the photoconductor 1 by the subsequent rotation of the photoconductor 1, and reaches the developing device 4 as shown in FIG. At this time, 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, the negative polarity toner T ₃ redeposited on the photoconductor 1 is electrostatically transferred to the developing roller 5 side. , Collected in the developer in the developing device.

As described above, the cleaning roller 12
On the surface thereof, electrostatically and temporarily collects the transfer residual toner T ₁ that has been triboelectrically charged, and then the collected toner T ₂
Is electrostatically redeposited on the surface portion of the image carrier composed of the photoconductor 1 that does not affect the formation of the next electrostatic latent image, and
The toner T ₃ redeposited on the surface of the image carrier is the developing device 4
Is electrostatically recovered at. 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 transport pipe for returning the toner collected by the cleaning roller 12 to the developing device 4.

As shown in FIG. 9, when the collected toner on the cleaning roller 12 is completely attached to the photosensitive member 1, the cleaning roller 12 is again charged with a toner having a polarity opposite to that of the toner during development. A voltage of positive polarity is applied, and the cleaning roller 12 is rotationally driven in, for example, a counter direction with respect to the rotational direction of the photoconductor 1, so that a very small amount of toner that should not originally adhere to the photoconductor 1 is present. However, it is preferable to control the cleaning roller 12 so that the toner is collected when the toner is attached.

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.

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

In the state shown in FIG. 9, neither the electrostatic latent image nor the toner image has been formed in the next image forming area X1. To be precise, the area X1 shown in FIG. It can be said that the area is to be the next image forming area. In addition, in FIGS. 1 and 2 to 11, the toner T, T ₁ , T ₂ , T on the photoconductor 1 or the cleaning roller 12 is used.
₃ and T ₄ are schematically shown in enlarged form.

As described above, the toner T ₂ collected by the cleaning roller 12 is the non-image forming area W on the photoconductor 1.
The redeposited toner T ₃ does not affect not only the electrostatic latent image at the time of the image forming operation described above but also the electrostatic latent image formed next. It is also possible to re-adhere the toner from the cleaning roller 12 to the rear portion of the image forming area X.

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

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

As described above, by applying the bias voltage having the polarity opposite to the charging polarity of the toner at the time of development to the cleaning member, the transfer residual toner on the image carrier is electrostatically transferred to the cleaning member. It is possible,
As a result, the transfer residual toner can be collected by the cleaning member. Further, after the collection, the polarity of the bias voltage applied to the cleaning member is switched, and the bias voltage having the same polarity as the charging polarity of the toner at the time of development is applied to the cleaning member, so that the toner collected on the cleaning member is carried as an image. It can be electrostatically transferred to the body. As a result, the collected toner can be reattached to the image carrier, and the reattached toner can be electrostatically collected in the developing device.

Here, in FIG. 1, the transfer paper 16 which is an example of the recording medium is transferred from a paper feeding unit (not shown) to the transfer unit 8.
Then, the sheet is sent to the outside of the image forming apparatus through the transfer unit 8 and a fixing device (not shown). However, a jam may occur on the transfer sheet during the conveyance of the transfer sheet. is there.

The image forming apparatus of this embodiment is provided with jam detecting means (not shown) at various places in the transfer sheet conveying path, and when a jam is detected by the detecting means, the main body of the image forming apparatus including the photoconductor 1 is detected. The driving of the rotating elements inside is stopped. That is, when the transfer sheet is jammed while the image forming operation is being executed, the motor for driving the rotating element is stopped, and the image forming operation is stopped.
After the image forming operation is stopped, the operator removes the jammed paper, presses a print button (not shown), and restarts the image forming apparatus. Then, the next image forming operation is executed.

By the way, for example, when the above-described jam occurs while the transfer residual toner on the photoconductor 1 is being collected by the cleaning roller 12, as shown in FIG. Between the device and a cleaning member comprising the cleaning roller 12,
The transfer residual toner T ₁ remains on the peripheral surface area of the photosensitive member on the downstream side of the transfer roller 7.

That is, as shown in FIG. 12, when a jam occurs before the rear end Z of the image forming area X reaches the transfer portion 8, the photosensitive member circumference between the transfer portion 8 and the cleaning portion 14 is generated. The transfer residual toner T ₁ remains in the surface area.
On the other hand, as shown in FIG. 13, the trailing edge Z of the image forming area X passes through the transfer portion 8 and comes to a position between the transfer portion 8 and the cleaning portion 14 to cause a jam. Even
The transfer residual toner T ₁ remains in the peripheral surface area of the photoconductor between the transfer section 8 and the cleaning section 14.

A jam occurs even before the trailing edge Z of the image forming area X reaches the transfer portion 8 or reaches a position between the transfer portion 8 and the cleaning portion 14. In this case, the transfer residual toner T ₁ remains on the entire area or a part of the peripheral surface area of the photoconductor between the transfer section 8 and the cleaning section 14. In addition, the front end Y (FIG. 3) of the image forming area X is located between the transfer portion 8 and the cleaning portion 14 shown in FIG. Even if a jam occurs while the toner is present, the transfer residual toner T ₁ similarly remains in the peripheral surface region between the two. When the transfer residual toner is being collected, the collected toner T ₂ naturally remains on the peripheral surface of the cleaning roller 12.

As described above, the transfer residual toner T
_{Since 1} is before the triboelectric charging between the cleaning roller 12 and the photoconductor 1, in addition to the negatively charged toner which is the original polarity, there is a transfer charging effect on the toner. Some toner has been positively charged. On the other hand, the collected toner T ₂ remaining on the cleaning roller 12 has already been triboelectrified, so that it has the original negative charging polarity.

Conventionally, no particular consideration has been given to how to efficiently treat the toner remaining on the photoconductor 1 and the cleaning roller 12 when the image forming apparatus is restarted after the jam processing. Therefore, if a jam occurs when the transfer residual toner T ₁ remains in the peripheral surface area, or when the image forming apparatus is restarted,
If the transfer residual toner T ₁ (including the untransferred toner T in the case of FIG. 12) is not collected by the cleaning roller 12 but collected by the developing device 4 (FIG. 1) as it is, the normal charging polarity is obtained. The untransferred residual toner (in this example, the positive transfer residual toner) is carried on the photoconductor 1 together with the transfer residual toner having the regular charging polarity and conveyed to the developing unit 6 (FIG. 1), so that the regular charging is performed. Transfer residual toner having no polarity cannot be electrostatically collected by the developing device 4, and the toner remains attached on the photoconductor 1.
This adhesion causes a background stain on the image, and the image quality is likely to deteriorate.

When a jam occurs while the transfer residual toner is being collected by the cleaning roller 12,
If the recovery toner T ₂ remaining on the cleaning roller 12 is not re-adhered to the photoconductor 1 when the image forming apparatus is restarted and the process proceeds to the next image forming operation as it is, the image formation after the jam processing is performed. During operation, the toner collection efficiency from the photoconductor 1 to the cleaning roller 12 decreases, and the cleaning efficiency for the photoconductor 1 decreases.

Therefore, in the image forming apparatus of this embodiment,
With respect to the rotation direction of the image carrier composed of the photoconductor 1, the peripheral surface region of the image carrier located downstream of the transfer device composed of the transfer roller 7 and upstream of the cleaning member composed of the cleaning roller 12, that is, As shown in FIGS. 12 and 13, in the peripheral surface area of the photoconductor between the transfer portion 8 and the cleaning portion 14, the transfer residual toner T ₁ exists,
When a jam occurs on the recording medium made of the transfer paper 16 (not shown in FIG. 12), the transfer residual toner remaining on the photoconductor 1 is controlled by the control unit (not shown) when the image forming apparatus is restarted. Of the collected toner to the cleaning roller 12, re-adhesion of the collected toner and collected toner remaining on the cleaning roller 12 to the photoconductor, and collection operation of the re-adhered toner to the developing device 4. Each is configured as follows.

That is, when the image forming apparatus is restarted, while the image carrier composed of the photoconductor 1 is rotationally driven in the rotational direction at the time of the image forming operation by the control means, the jam is caused by the cleaning member composed of the cleaning roller 12. The toner remaining on the surface of the photoconductor 1 at the time of occurrence is electrostatically collected, then the collected toner is electrostatically redeposited on the surface of the photoconductor 1, and the redeposited toner is statically attached to the developing device 4. The electrical recovery mode is executed. A control means for performing such a series of controls is provided.

As shown in FIG. 12, when a jam occurs before the trailing edge Z of the image forming area X reaches the transfer portion 8,
In this state, the rotation of the photoconductor or the like is stopped, and in this state, the operator removes the transfer paper 16 (FIG. 1) in which the jam has occurred. After that, the print button (not shown) is pressed to turn on the image forming apparatus. When restarted, the photoconductor 1 rotates clockwise in the figure, and the cleaning roller 12 rotates clockwise (see FIG. 3) in the figure.
At this time, the cleaning roller 12 has, for example, +20, which has a polarity opposite to the charging polarity of the toner at the time of development described above.
A bias voltage of 0V is applied. The same operation as the toner collecting operation during the image forming operation is executed, and the cleaning roller 12 and the photoconductor 1 transfer the residual toner T
_{While 1} is frictionally charged to the charging polarity of the toner at the time of development, the polarity is made uniform and electrostatically collected. In addition to the toner T ₂ already collected, the cleaning roller 12 collects the transfer residual toner T ₁ when the image forming apparatus is restarted. At this time, the untransferred toner T is also electrostatically collected by the cleaning roller 12 at the same time. As shown in FIG. 13, when a jam occurs when the trailing edge Z of the image forming area X comes between the transfer portion 8 and the cleaning portion 14, when the image forming apparatus is restarted, the transfer residual amount is left. Only the toner T ₁ is electrostatically collected by the cleaning roller 12.

When all the toner is collected, the cleaning roller 12 is applied with a voltage of the same polarity as that of the collected toner, for example, -3000 V, and the roller 12 rotates counterclockwise in the figure, The collected toner is electrostatically redeposited on the photoconductor 1. The same operation as the toner readhesion operation during the image forming operation is executed.
The re-adhered toner passes through the charging roller 2 separated from the photoconductor 1 by the subsequent rotation of the photoconductor 1,
It is conveyed to the developing unit 6 (FIG. 1). At this time, a bias voltage having a polarity opposite to that of the re-adhesion toner, for example, +500 V is applied to the development roller 5 of the development device 4, and thus the re-adhesion toner is electrostatically collected by the development device 4. This is the same operation as the recovery of the reattached toner to the developing device 4 during the image forming operation. The next electrostatic latent image is formed on the photosensitive member 1 behind the redeposited toner in the same manner as in the case of FIG. Following the recovery of the re-adhered toner to the developing device 4, the image forming operation after the jam processing is started.

According to the above construction, when the transfer residual toner T ₁ remains in the peripheral surface area of the photosensitive member between the transfer portion 8 and the cleaning portion 14 as shown in FIGS.
The residual transfer residual toner is not directly recovered by the developing device 4, but is triboelectrically charged between the cleaning roller 12 and the photoconductor 1 so that the residual transfer residual toner is aligned in its original polarity. Since the toner is conveyed to 6, the toner can be electrostatically collected in the developing device 4 without any trouble. Since it is possible to prevent the toner that is not originally charged with the polarity from being collected by the developing device, it is possible to prevent the occurrence of the background stain that occurs when the toner remains attached to the photoconductor.

Further, as shown in FIGS. 12 and 13, the collected toner T ₂ on the cleaning roller 12 is not left as it is and is reattached to the photoconductor 1 together with the newly collected transfer residual toner. When the toner is collected during the image forming operation, this collection can be performed without any trouble. It is possible to prevent the cleaning efficiency from decreasing.

When the untransferred toner T of the toner image shown in FIG. 12 passes through the transfer roller 7, if this toner adheres to the transfer roller 7, it adheres to the transfer paper during the next image forming operation. Since the transfer paper is contaminated with the toner, when the toner T passes through the transfer roller 7, the
0 and FIG. 13, the transfer roller 7 may be separated from the photoconductor 1 by a contact / separation drive unit (not shown), or when the untransferred toner T passes through the transfer roller 7, the transfer roller 7 may be separated. When the photoconductor 1 is rotated in the forward direction with the photoconductor 1 kept in contact with the photoconductor 1, the switch S ₁₁ shown in FIG.
A voltage having the same polarity as that of the untransferred toner T is applied to the transfer roller 7 by ₃ ', whereby the toner T is transferred to the transfer roller 7.
It can also be prevented from adhering to. Transfer roller 7
May be separated from the photoconductor 1 and a voltage having the same polarity as the untransferred toner T may be applied to the roller 7. In any case, the toner may be prevented from adhering to the transfer roller 7. It controls the roller 7. When a corona discharger separated from the photoconductor 1 is used as the transfer device, such control can be dispensed with.

Next, the rear end Z of the image forming area X on the photosensitive member 1 in the photosensitive member rotating direction passes through the cleaning roller 12,
When a jam occurs on the transfer sheet while the collected toner remains on the cleaning roller 12, it remains on the cleaning roller 12 by the above-mentioned control means (not shown) when the image forming is restarted thereafter. Reattachment of the existing toner to the photoconductor 1 and recovery of the reattached toner to the developing device 4 are performed as follows.

That is, when the trailing end of the image forming area on the image bearing member in the direction of rotation of the image bearing member passes through the cleaning member and the collected toner remains on the cleaning member, the recording medium is jammed. When the image forming apparatus is restarted later, while the image carrier composed of the photoconductor 1 is rotationally driven in the rotational direction during the image forming operation by the control means,
A mode is executed in which the residual recovered toner on the cleaning member including the cleaning roller 12 is electrostatically redeposited on the surface of the image carrier, and the redeposited toner is electrostatically recovered on the developing device 4. The control means of this example also performs such a series of controls.

FIG. 7 shows a state in which the trailing edge Z of the image forming area Z reaches the position of the cleaning roller 12, and the trailing edge Z of the image forming area X reaching this position is
As shown in FIG. 8, when a jam occurs while passing through the cleaning member 12, the image forming operation is stopped and the rotation of the photoconductor or the like is stopped.
The transfer paper having the jam is removed. When a print button (not shown) is pressed thereafter to restart the image forming apparatus, the photoconductor 1 rotates in the clockwise direction in the drawing and the cleaning roller 12 Rotates counterclockwise (arrow direction) in the figure. At this time, a voltage of, for example, −3000 V having the same polarity as the charge polarity of the collected toner is applied to the cleaning roller 12. The same operation as the operation of re-adhering the collected toner to the photoconductor 1 during the image forming operation is executed. As a result, the collected toner T ₂ on the cleaning roller 12 is electrostatically redeposited on the non-image forming area W of the photoconductor 1, and the redeposited toner is
Due to the subsequent rotation of the photoconductor 1, the toner T ₃ already redeposited on the photoconductor 1 passes through the charging roller 2 separated from the photoconductor 1, and is conveyed to the developing device 4. At this time, the re-adhesion toner is applied with a bias voltage of the opposite polarity, for example, +500 V, to the development roller 5 of the development device 4, and thus the re-adhesion toner conveyed to the development device 4 is
It is electrostatically recovered by the developing device 4. This is the same operation as the recovery of the reattached toner to the developing device 4 during the image forming operation. The next electrostatic latent image is formed on the photoconductor 1 behind the re-adhered toner as in the case of FIG. In this way, the image forming operation after the jam processing is started following the recovery of the reattached toner to the developing device 4.

Assuming that the rear end Z of the image forming area X has passed the cleaning roller 12 as shown in FIG.
When a jam occurs, when the image forming apparatus is restarted, the collected toner T ₂ on the cleaning roller 12 may be left on the cleaning roller 12 without being reattached to the photoconductor 1, and the image forming operation may be restarted. For example, when the toner is collected during the image forming operation, the toner collecting capability cannot keep up with the cleaning efficiency.

In the present embodiment, the re-adhesion of the recovered toner T ₂ shown in FIG. 8 to the photoconductor 1 and the recovery of the re-adhered toner to the developing device 4 are carried out, respectively. And the cleaning efficiency at the time of the next toner recovery does not decrease. Toner T collected on the cleaning roller 12
₂ is already triboelectrically charged between the cleaning roller 12 and the photoconductor 1 and is aligned with the charging polarity of the toner at the time of development. Therefore, the toner is re-deposited on the photoconductor 1 and then this toner is applied to the developing device. When it is collected in No. 4, it can be surely collected electrostatically.

Next, as shown in FIG. 14, the tip of the toner image on the photoreceptor 1 in the direction of rotation of the photoreceptor, that is, the tip Y of the image forming area X is transferred to the transfer portion 8 where the transfer device transfers the toner image. When a jam occurs on the recording medium made of the transfer paper 16 before reaching, when the image forming apparatus is restarted thereafter, the above-mentioned control means (not shown) causes
The toner (untransferred toner) T in the image forming area X is straightly collected in the developing device 4.

That is, at the time of restarting the image forming apparatus after the jam processing, the image carrier composed of the photoconductor 1 is rotationally driven in the rotational direction at the time of the image forming operation by the control means, and the toner image not yet transferred to the toner is transferred. The toner of the toner image is retained on the image carrier without being collected by the cleaning member including the cleaning roller 12, and the untransferred toner T
That is, the mode in which the electrostatic latent image is collected by the developing device 4 is executed. The control means of this example also performs such a series of controls.

FIG. 14 shows the state before the leading edge Y of the image forming area X reaches the transfer portion 8 as described above. In this state, the transfer paper 16 is jammed. At this time, the image forming operation is stopped and the rotation of the photoconductor or the like is stopped, and the operator removes the transfer sheet with the jam, but after that, press the print button (not shown) to restart the image forming apparatus. When started, the photoconductor 1 rotates clockwise in the drawing, the negatively charged untransferred toner T passes through the transfer unit 8 and the cleaning unit 14, respectively, and is directly and electrostatically applied to the developing device 4 as it is. Be recovered. That is, at this time, the developing roller 5 of the developing device 4
Has a polarity opposite to that of the untransferred toner T, for example, + 500V.
Bias voltage is applied, whereby the untransferred toner T is electrostatically collected by the developing device 4. The next electrostatic latent image is formed on the photosensitive member 1 behind the untransferred toner T as shown in FIG.
It is formed in the same manner as in the case of 0. Following the recovery of the untransferred toner T to the developing device 4, the image forming operation after the jam processing is started.

The untransferred toner T adhering to the photosensitive member at the time of occurrence of a jam has not yet passed through the transfer roller 7, so that substantially all of the toner remains in the negative polarity. . Therefore, even if the toner is directly recovered by the developing device 4 after the jam processing, it can be reliably electrostatically recovered by the developing device 4.

Here, if a jam occurs before the tip Y of the image forming area X reaches the transfer portion 8, the untransferred toner T is once collected on the cleaning roller 12 when the image forming apparatus is restarted. If the collected toner is reattached to the photoconductor and collected by the developing device 4, the toner on the cleaning roller 12 will be transferred to the cleaning roller 12 in a time period from the press of the print button to the start of image formation after the jam processing. Since the collection time will be included, its start will be delayed. The time for enabling image formation becomes longer.

In the present embodiment, when a jam occurs before the image front end Y reaches the transfer portion 8, the untransferred toner T is collected on the cleaning roller 12 at the next restart of the image forming apparatus. Since the configuration is such that the image is directly collected in the developing device 4 without performing it, it is possible to shorten the time for enabling image formation when the image forming device is restarted.

Also in this case, when the untransferred toner T shown in FIG. 14 passes through the transfer roller 7 when the image forming apparatus is restarted, is this roller 7 separated from the photosensitive member 1 by the contact / separation drive means? Alternatively, while rotating the transfer roller 7 in the forward direction with respect to the photoconductor 1, the power source E shown in FIG.
_The transfer roller 7 is controlled so that the toner T does not adhere to the transfer roller 7 by applying a negative voltage having the same polarity as that of the untransferred toner T by ₃ '. By this processing,
It is also possible to prevent the untransferred toner T from being charged by the transfer roller 7 to a polarity opposite to the charging polarity at the time of development.

When the image forming apparatus is restarted, the untransferred toner T shown in FIG.
When the cleaning roller 12 is reached,
By applying a voltage having the same polarity as that of the toner T by the power source E ₅ shown in FIG. 1 or by simultaneously applying the voltage and rotating the cleaning roller 12 in the forward direction with respect to the photoconductor 1, the untransferred toner is not transferred. T is the cleaning roller 12
This can be directly conveyed to the developing device 4 without being collected. The cleaning roller 12 is caused to execute the same operation as the toner re-adhesion operation during the image forming operation.

On the other hand, instead of the configuration in which the cleaning roller 12 shown in FIG. 14 is kept in contact with the photoconductor 1, a configuration in which the cleaning roller can be brought into and out of contact with the photoconductor 1 may be adopted. When the untransferred toner T passes through the cleaning unit 14, the cleaning roller 12 is separated from the photoconductor 1, and after the passage, the cleaning roller 1
2 is brought into contact with the photoreceptor 1.

Even when such a structure is adopted, the untransferred toner T can be passed through the cleaning roller 12 without being collected, and can be directly conveyed to the developing device 4. Moreover, in this case, the switch S ₂ shown in FIG.
It is possible to pass the untransferred toner at the cleaning portion 14 without switching to the negative voltage power source E ₅ , and the toner can be electrostatically collected in the developing device 4 without any trouble.

As the driving means for bringing the cleaning roller 12 into and out of contact with the photosensitive member 1, for example, the following structure can be adopted.

1 and 15, the cleaning case 17 for accommodating the cleaning roller 12 is rotatably supported by a pair of image forming apparatus main body side plates (not shown) by a pivot shaft 19.
A tension spring 18 is hung between the plate and the body side plate. The central axis of both pivots 19, that is, the swing axis of the cleaning case 17 is
And extends parallel to the center of rotation of the photoconductor 1 (FIG. 1).

The cam shaft 21 extending substantially in parallel with the cleaning roller 12 is rotatably supported around a central axis thereof by a pair of image forming apparatus main body side plates (not shown) facing each other. A pair of contact / separation switching cams 22 is fixedly mounted on the shaft, and one shaft end of the cam is connected to a motor 23.

Plain, cleaning case 1 shown in FIG.
7, the tension spring 1 is provided on the back wall surface on the side opposite to the photoconductor 1.
Due to the elastic force of 8, the cam surface 22a of the cam peripheral surface of the switching cam 22 is in pressure contact. In this state, the cleaning roller 12 which is rotatable with respect to the cleaning case 17 but is fixed in position is in contact with the photoconductor 1. As described above, the cleaning roller 12 is in contact with the photoconductor 1 in the normal state, but when the image front end Y shown in FIG. 14 approaches the cleaning unit 14, the motor 23 shown in FIG.
Rotate for a predetermined time in the direction of the arrow in the figure, which causes the cam 22 shown in FIG. 1 to rotate counterclockwise to the position shown in FIG.

Then, during this period, the cleaning case 17 shown in FIG. 1 rotates around the pivot 19 in the clockwise direction in the figure. And the cleaning case 17
16 is stopped by the stopper pin 24 provided on the side plate of the main body, as shown in FIG.
2 is held at a position separated from the photoconductor 1. That is, of the cam peripheral surface of the switching cam 22, the cam surface portion 22
When c comes to the position facing the cleaning case 17,
The cleaning roller 12 is completely separated from the photoconductor 1. The cam surface portion 22c is set at a position closest to the axial center of the cam shaft 21 on the cam peripheral surface.

When the untransferred toner T shown in FIG. 14 has finished passing through the cleaning unit 14, the motor 23 (FIG. 15) is rotated again in the opposite direction to that of FIG. 1 rotates in the clockwise direction in the figure to the position shown in FIG. 1, the cam surface 22a presses against the cleaning case 17 again, pushes the cleaning case, and presses the cleaning roller 12 against the photoconductor 1. . In this way, the cleaning roller 12 is attached to the photoreceptor 1.
By adopting a configuration in which the untransferred toner T is not contacted with the switch S ₂ (FIG. 1),
(FIG. 14) can be passed through at the cleaning unit 14, and the toner can be electrostatically collected in the developing device without any trouble.

During the normal image forming operation described above, the transfer residual toner T ₁ on the photosensitive member 1 that has passed through the transfer portion 8 shown in FIG. 1 has a polarity opposite to the charging polarity of the toner during development. In this example, the charged toner (referred to as an abnormal polarity toner) is mixed, and in this example, the abnormal polarity toner is triboelectrically charged with the cleaning roller 12 so as to have the same polarity as the charging polarity of the toner at the time of development. There is. 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 Polar toner)
The mechanical scraping force received from the cleaning roller 12 adheres to the surface of 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, in the image forming apparatus of this example, as shown in FIG. 2, the transfer residual toner T is transferred during the normal image forming operation.
_{When 1} is collected from the photoconductor 1 to the cleaning roller 12, as described above, in the contact region between the photoconductor 1 and the cleaning roller 12, that is, in the nip region N where these are in pressure contact, they are in opposite directions. The cleaning roller 12 is moved so as to move in the (counter direction).
Control the rotation direction of the cleaning roller 12 and
Is less than one rotation of the transfer residual toner T ₁ on the photoconductor _1.
The rotation of the cleaning roller 12 is controlled so that the cleaning roller 12 collects. With the rotation of the cleaning roller 12 less than one rotation, the operation for collecting the transfer residual toner T ₁ on the photoconductor 1 is completed. It is preferable to control the cleaning roller 12 in the same manner when the image forming apparatus is started after the jam processing and when the residual toner on the photoconductor 1 is collected by the cleaning roller.

With this configuration, the cleaning roller 12
The toner T ₂ collected in the
It does not contact the photoreceptor 1 again. 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.

If the transfer residual toner T ₁ is collected by the cleaning roller 12, the cleaning roller 12
2 in the nip region N with the photoconductor 1 as shown by the chain line arrow b in FIG. 2, when both are moved in the same direction (forward direction), will be the presence of the recovery toner T ₄ on the cleaning roller 12, when the 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 same positive polarity Since the voltage is applied, the positive polarity toner T ₄ is electrostatically attracted toward the photoconductor 1 and adheres to the surface of the photoconductor. 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.

In order to eliminate such a defect, as described above, the cleaning roller 12 rotates so that the cleaning roller 12 rotates in the counter direction with respect to the rotation direction of the photosensitive member 1, that is, in the direction of the solid arrow a in FIG. The direction is set.

At this time, if the cleaning roller 12 is rotated once or more to collect the transfer residual toner from the photoconductor 1, if the toner collected by the cleaning roller 12 has an abnormally positive polarity. When the toner is present, when the toner approaches the photoconductor 1 again or comes in contact with the photoconductor 1, the toner adheres to the photoconductor 1 and cleaning failure of the photoconductor 1 occurs. Therefore, in this example, the toner collecting operation from the photoconductor 1 to the cleaning roller 12 is completed while the cleaning roller 12 is rotationally driven for less than one rotation.

According to the above construction, the cleaning roller 1
It is possible to make it difficult to transfer the toner (abnormal polarity toner) having a polarity opposite to the charge polarity at the time of development, which is collected in No. 2, to the photoconductor 1.

The cleaning roller 12 for reattaching the collected toner on the cleaning roller 12 to the photoconductor 1
May rotate in any direction. In this example, as described above, in the nip region N with the photoconductor 1, the cleaning roller 12 and the photoconductor 1 have the same direction (the direction of the chain line arrow b in FIG. 2). The rotation direction of the cleaning roller 12 is controlled so that the cleaning roller 12 rotates. Moreover, the rotation speed thereof is set higher than that at the time of toner recovery, and the photosensitive member 1 is rotated at a speed higher than the peripheral speed so that the toner can be reattached to the photosensitive member 1 efficiently in a short time.

Further, with the cleaning member stopped,
It is also possible to collect toner from the image carrier or to reattach the collected toner to the image carrier.

The present invention is an image forming apparatus that uses a roller-shaped cleaning member, an endless belt-shaped cleaning member, or an endless belt-shaped cleaning member as the image carrier. It can also be applied to devices. 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 of the image bearing member, and the latent image potential is charged to the opposite polarity. It can also be applied to a so-called positive / positive developing type image forming apparatus in which the generated toner is adhered to the electrostatic latent image to perform development.

[0090]

According to the image forming apparatus of the present invention, the transfer residual toner on the image carrier is electrostatically collected by the cleaning member, and the collected toner is electrostatically collected by the image carrier. In the image forming apparatus, the image forming operation is stopped when the reattached toner is electrostatically collected by the developing device and the recording medium is jammed. Even if the transfer residual toner remains in the peripheral surface area of the image carrier between them, when the image forming apparatus is restarted, the transfer residual toner is sufficiently frictionally charged and electrostatically collected by the cleaning member, and , The collected toner electrostatically redeposits on the image carrier and is collected in the developing device, so that the toner having a polarity opposite to the charging polarity at the time of development is prevented from remaining adhered to the image carrier. Can and takes opposite polarity The occurrence of background stains on the originating image to the toner adhesion can be prevented.

According to the image forming apparatus of the second aspect,
When the transfer residual toner on the image bearing member is collected by the cleaning member, the collected toner is reattached to the image bearing member, then the reattached toner is collected by the developing device, and when a jam occurs on the recording medium, In an image forming apparatus in which the image forming operation is stopped, when a jam occurs, the collected toner remaining on the cleaning member does not remain on the cleaning member when the image forming apparatus is restarted, and electrostatically adheres to the image carrier. Since the re-adhered toner is electrostatically recovered by the developing device, the next toner recovery by the cleaning member can be carried out without a decrease in cleaning efficiency.

According to the image forming apparatus of the third aspect,
When the transfer residual toner on the image bearing member is collected by the cleaning member, the collected toner is reattached to the image bearing member, then the reattached toner is collected by the developing device, and when a jam occurs on the recording medium, In an image forming apparatus in which the image forming operation is stopped, when a jam occurs, the untransferred toner remaining on the image carrier is directly collected by the developing device without being collected by the cleaning member when the image forming apparatus is restarted. Therefore, after restarting the image forming apparatus, it is possible to shorten the time required to enable image formation.

[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 toner and a frictional contact portion between the photosensitive member and the cleaning roller, 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 how the redeposited toner on the photoconductor is collected by the developing device.

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 a view similar to FIG. 3 showing a state in which a transfer residual toner and an untransferred toner remain on a photoconductor due to a jam before the rear end of the image forming area reaches the position of the transfer portion. FIG.

FIG. 13 is an explanatory diagram similar to FIG. 3, illustrating a state in which a jam has occurred and transfer residual toner remains on the photoconductor before the trailing edge of the image forming area reaches the position of the cleaning unit.

FIG. 14 is an explanatory diagram similar to FIG. 3, showing a state in which a jam occurs before the leading edge of the image forming area reaches the position of the transfer portion, and untransferred toner remains on the photoconductor.

FIG. 15 is a partial cross-sectional view of a peripheral configuration portion of a cleaning roller that is brought into contact with and separated from a photoconductor by the action of a contact / separation switching cam.

FIG. 16 is a partial cross-sectional view of the peripheral configuration part of the cleaning roller separated from the photoconductor by the action of the contact / separation switching cam.

[Explanation of symbols]

4 Developing Device 8 Transfer Part T Toner T ₁ Toner T ₂ Toner T ₃ Toner X Image Forming Area X1 Image Forming Area Z Rear Edge

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

Claims (3)

[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. Between the transfer device that transfers the toner image on the image carrier to the recording medium 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 during development. The transfer residual toner is triboelectrically charged, and the triboelectrically charged transfer residual toner is temporarily collected electrostatically, and the collected toner is used for forming the next electrostatic latent image on the image carrier. A cleaning member that electrostatically redeposits on an unaffected surface portion is provided, and the toner redeposited on the surface of the image carrier is electrostatically collected by the developing device and an image forming operation is performed. In this state, when a jam occurs on the recording medium, the image forming operation stops In the image forming apparatus, the transfer residual toner is present in the peripheral surface area of the image carrier on the downstream side of the transfer device and the upstream side of the cleaning member with respect to the rotation direction of the image carrier. When a jam occurs on the recording medium, when the image forming apparatus is restarted thereafter, the image carrier is rotated in the rotation direction during the image forming operation, and is left on the surface of the image carrier by the cleaning member by the cleaning member. Control means for performing a mode in which the collected toner is electrostatically collected, the collected toner is electrostatically redeposited on the surface of the image carrier, and the redeposited toner is electrostatically collected in the developing device. An image forming apparatus characterized by being provided. 2. An image carrier that is rotationally driven, 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. Between the transfer device that transfers the toner image on the image carrier to the recording medium 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 during development. The transfer residual toner is triboelectrically charged, and the triboelectrically charged transfer residual toner is temporarily collected electrostatically, and the collected toner is used for forming the next electrostatic latent image on the image carrier. A cleaning member that electrostatically redeposits on an unaffected surface portion is provided, and the toner redeposited on the surface of the image carrier is electrostatically collected by the developing device and an image forming operation is performed. In this state, when a jam occurs on the recording medium, the image forming operation stops In the image forming apparatus, when a trailing edge of the image forming area on the image bearing member in the rotational direction of the image bearing member passes through the cleaning member and the collected toner remains on the cleaning member, a jam occurs on the recording medium. When the image forming apparatus is restarted thereafter, the residual collected toner on the cleaning member is electrostatically redeposited on the surface of the image carrier while rotating the image carrier in the rotation direction during the image forming operation. An image forming apparatus, comprising: a control unit that executes a mode of electrostatically collecting the reattached toner to a developing device. 3. 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. Between the transfer device that transfers the toner image on the image carrier to the recording medium 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 during development. The transfer residual toner is triboelectrically charged, and the triboelectrically charged transfer residual toner is temporarily collected electrostatically, and the collected toner is used for forming the next electrostatic latent image on the image carrier. A cleaning member that electrostatically redeposits on an unaffected surface portion is provided, and the toner redeposited on the surface of the image carrier is electrostatically collected by the developing device and an image forming operation is performed. In this state, when a jam occurs on the recording medium, the image forming operation stops In the image forming apparatus, when the leading edge of the toner image on the image bearing member in the image carrier rotating direction reaches the transfer portion where the toner image is transferred by the transfer device, when a jam occurs on the recording medium, When the image forming apparatus is restarted, the toner of the toner image is transferred to the image carrier without rotating the image carrier in the rotation direction during the image forming operation and collecting the toner of the toner image to the cleaning member. An image forming apparatus comprising: a control unit that allows a developing device to electrostatically collect the toner while allowing it to pass through a cleaning member while being held above.