JPH09127844A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of image deterioration in toner image due to paper powder by removing the paper powder incorporated in toner, which remains after a transfer and is recovered to a cleaning member, before the paper powder is carried to a developing device. SOLUTION: As a paper powder removing means, a brush 16, whose top end part abuts on the periphery of a cleaning roller 12, is used. Then, a brush attaching bracket 18 is fixed in a cleaning case 17 and the base end part of the brush 16 is fixedly provided on a supporting plate 19 fixed on the bracket 18. The brush top end part on the free end side of the brush 16 abuts on the periphery of the cleaning roller 12. While the roller 12 is rotated to recover the toner remaining on a photoreceptor 1 after the transfer to the roller 12 is performed, the brush 16 scrapes/removes the paper powder incorporated in the toner. Since the paper powder is removed before it goes to the developing device 4, the intrusion of the paper powder into the developing device 4 can be prevented and the occurrence of the deterioration in the image quality of the toner image due to the paper powder can be prevented as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention visualizes an electrostatic latent image formed on a rotationally driven image carrier as a toner image by a developing device, and transfers the toner image onto a recording medium at a transfer section. The present invention relates to an image forming apparatus that cleans the surface of an image carrier by collecting the toner remaining on the image carrier after the transfer of the toner image with a cleaning member.

[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 remove and collect the residual adhered toner with 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 the above points, for example, when 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 transfer, 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 next best measure, the toner remaining on the surface of the image carrier after the transfer of the toner image (hereinafter, referred to as "transfer residual toner" if necessary) is attached to the cleaning member and collected, Then, a method is proposed in which the recovered toner is reattached to the image carrier, recovered by a developing device, and reused in the developing device (for example, Japanese Patent Publication No. 61-
30274 gazette). With this configuration, since the means for transferring the scraped toner to the waste toner tank is unnecessary, the cost of the image forming apparatus can be reduced, and the toner can be recycled for use, so that the waste toner can be eliminated. .

In the image forming apparatus of this type, the transfer residual toner is collected from the surface of the image bearing member onto the cleaning member, and the toner is re-adhered to the image bearing member again. Contains foreign matter such as paper dust. Such toner redeposits on the image carrier,
When this is collected and reused in the developing device, for example, paper powder is clogged between the developer carrying and conveying member of the developing device and the developer regulating member facing the developer carrying member, which forms on the image carrier. A streak-shaped image omission (so-called white omission) occurs on the formed toner image, and the image quality deteriorates.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to remove paper dust mixed in the toner recovered by the cleaning member from the cleaning member to prevent the paper dust from entering the cleaning device. Then, an object of the present invention is to provide an image forming apparatus capable of suppressing the occurrence of image quality deterioration of a toner image due to paper dust.

[0008]

To achieve the above object, the present invention visualizes an electrostatic latent image formed on a rotationally driven image carrier as a toner image by a developing device,
The toner image is transferred to a recording medium by a transfer unit, and after the toner image is transferred, the toner remaining on the image carrier is temporarily collected by a cleaning member, and then the collected toner is
In the image forming apparatus for re-adhering to the surface portion of the image carrier that does not affect the formation of the next latent image, and for collecting the re-adhered toner in the developing device, the toner collected in the cleaning member is mixed. An image forming apparatus is proposed, which is provided with a paper dust removing unit for removing the paper dust existing outside the cleaning member.

At this time, it is advantageous to use a brush whose tip contacts the cleaning member as the paper dust removing means.

Further, as the paper dust removing means, a paper dust removing filter is provided in the air flow path from the cleaning member to the fan for generating the air flow for suction removal of the paper dust and the cleaning member. It is also advantageous to use a suction removal device.

Further, as a paper dust removing means, a brush whose end portion abuts the cleaning member to scrape the paper dust, a fan for generating an air flow for sucking and removing the paper dust, and the cleaning member to the fan. It is particularly advantageous to use a paper dust suction removal device having a paper dust removal filter provided in the air flow path.

Further, it is advantageous that the tip of the brush is in contact with the rotation direction of the cleaning member in the counter direction.

Further, it is advantageous to provide voltage applying means for applying a voltage to the brush so that the brush has the same potential as the cleaning member.

It is also advantageous to provide the brush with voltage applying means for applying a voltage having the same polarity as that of the toner collected by the cleaning member.

[0015]

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

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. In the figure, a drum-shaped photoreceptor 1 which is an example of the configuration of an image carrier is rotationally driven in the clockwise direction in the figure by a driving unit (not shown), and at the time of this rotation, first, a charging roller 2 which is an example of a charging device. By this action, the surface of the photoconductor 1 is uniformly charged to a predetermined polarity. In this example, it is assumed that the surface of the photoconductor 1 is uniformly charged to a negative (negative) polarity by the action of the charging roller 2. The surface of the photoconductor 1 is charged to, for example, −850V. As a charging device for uniformly charging the photoconductor 1,
A corona discharger or the like can also be used.

Next, in the exposure section 3, optical writing scanning is performed with the light-modulated laser beam 11, so that a predetermined electrostatic latent image is formed on the surface of the photoconductor 1.
In this way, the photoconductor 1 that is rotationally driven during image formation
An electrostatic latent image is formed on it. The potential of the portion A irradiated with the laser light that forms the electrostatic latent image is, for example, about −150 V, and the portion B not irradiated with the laser light.
The surface potential of is maintained at approximately -850V.

The developing device 4 comprises a developing roller 5 which is an example of a developer carrying and conveying member which is arranged to face the photoconductor 1.
A bias voltage of about -600 V, for example, is applied to the developing roller 5 by the bias voltage power source E ₁ . In the developing device 4 illustrated here, a two-component developer D having a toner and a carrier is used, and the toner has a predetermined polarity due to friction with the carrier, and in this example, has the same polarity as the charging polarity of the photoconductor 1. It is negatively charged.

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 carried toward the developing section 6 where the developer is carried. The toner inside is electrostatically attracted to the electrostatic latent image on the photoconductor 1 and adheres to that portion. That is, the toner charged to the same negative polarity as the charging polarity of the photoconductor adheres to the portion A irradiated with the laser beam, and the electrostatic latent image is visualized as a toner image. In this way, the electrostatic latent image is visualized as a toner image by the developing device 4. In the example of this image forming apparatus, a reversal development method (negative / positive development method) is adopted.

A transfer charging roller 7, which is an example of a transfer charging device, is disposed below the photoconductor 1. The transfer charging roller 7 rotates in the forward direction with respect to the photosensitive member 1, and a recording medium P made of, for example, transfer paper is transferred toward the transfer portion 8 between the transfer charging roller 7 and the photosensitive member 1 in contact therewith. The transfer charging roller 7 has the function of
The toner image formed on the photoconductor 1 is transferred to the recording medium P. That is, a voltage having a positive (plus) polarity opposite to the charge polarity of the toner of the toner image on the photoconductor 1 is applied to the transfer charging roller 7 by the power source E ₃ , for example, a voltage of +950 V is applied. The negative polarity toner T on the body 1 (this is schematically shown in large size)
The toner image is electrostatically attracted to the recording medium P side, adheres to the recording medium, and the toner image on the photoconductor 1 is transferred to the recording medium.

The recording medium P on which the toner image is transferred is separated from the photoconductor 1 by a separating device (not shown) and sent to a fixing device (not shown). Then, here, the toner image on the recording medium is fixed.

As described above, the toner image on the photoconductor 1 is transferred to the recording medium at the transfer portion 8, but after the transfer of the toner image, the toner not contributing to the transfer remains on the surface of the photoconductor 1. It is attached. When the residual toner reaches the cleaning unit 14, it is temporarily collected by a cleaning roller 12 which is an example of a cleaning member.

Here, in FIG. 1, most of the toner T of the toner image directed from the developing section 6 to the transfer section 8 is a negative polarity toner. On the other hand, since a positive transfer voltage is applied to the transfer charging roller 7 during the transfer of the toner image, the toner remaining on the photoreceptor 1 after the transfer of the toner image, that is, the transfer residual toner T ′ is The toner has a mixture of a positive polarity toner and a negative polarity toner. In this way, the transfer residual toner is transferred to the cleaning unit 14 in a state where the toners of both positive and negative polarities are mixed.

The cleaning roller 12 is made of, for example, a foam having a volume resistivity of medium resistance, and is rotated clockwise in the drawing, that is, in the counter direction with respect to the rotation direction of the photosensitive member 1. The photoconductor 1
Rotate while rubbing against the surface of. Cleaning roller 1
2 has its surface portion pressed against the photoconductor 1 so that the surface of the photoconductor 1 can be elastically deformed by the photoconductor 1, and as shown in FIG. This nip area N becomes the cleaning area 14.

In the nip region N, the transfer residual toner T'having both positive and negative polarities is in contact with the cleaning roller 12 and has the same polarity as the toner after development (negative polarity in this example).
The toner is triboelectrically charged. in this way,
The cleaning roller 12 also performs a function of frictionally charging the transfer residual toner with the photoconductor 1 and frictionally charging the toner so that the toner is aligned in the negative polarity which is the original polarity. That is, when the untransferred toner toward the cleaning member including the cleaning roller 12 includes toner charged to a polarity opposite to the charging polarity of the toner at the time of development, the toner has the charging polarity of the toner at the time of development (the original The toner is triboelectrically charged so that the toner can have the same polarity. Cleaning roller 1
2 is composed of a charging series charging material capable of frictionally charging the toner to its original polarity, in this example, negative polarity.

To the cleaning roller 12, a bias voltage having a positive polarity opposite to the charging polarity of the toner frictionally charged as described above, for example, a bias voltage of +200 V is applied by the bias voltage power source E ₄ . Here, the residual toner after the transfer of the toner image, that is, the residual transfer toner T ′, which has passed through the transfer unit 8, is electrostatically attracted to the cleaning roller 12 to which the positive bias voltage is applied, and the roller 12 is transferred. Adheres to the surface of and is temporarily collected by this roller 12. As a result, the surface of the photoconductor 1 is cleaned. In this way, the cleaning roller 12 is transferred to the photosensitive member 1 and the transfer residual toner T ′ on the photosensitive member 1 is transferred to the cleaning roller 12.
However, the bias voltage as described above is applied so that an electric field that can be electrostatically attracted is formed toward the cleaning roller 12.

The surface of the photoreceptor 1 is the cleaning roller 12
After being cleaned by, the surface thereof is discharged by the discharging lamp 13 which is an example of the discharging device, and the above-mentioned image forming operation is continued. In this way, one toner image is formed on the photoconductor 1 and transferred onto the recording medium P. The region on the photoconductor 1 on which the toner image is formed is the image forming region. The area after that is the non-image forming area. When the rear end of the image forming area 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.

When the trailing edge of the image forming area passes the developing roller 5 of the developing device 4, the switch S ₁ is switched, the developing roller 5 is connected to the bias voltage power source E ₂ , and the developing roller 5 is connected to the developing roller 5. In order to prevent the toner from adhering to the photoconductor 1, a positive bias voltage opposite to the charging polarity of the toner, for example, a voltage of + 500V is applied. When the trailing edge of the image forming area passes through the transfer portion 8, the voltage application to the transfer charging roller 7 is stopped at this time.

Further, when the trailing edge of the image forming area after the toner image is transferred onto the recording medium passes through the cleaning roller 12, the switch S ₂ is switched and the cleaning roller 12 is connected to the bias voltage power source E _5. Then, the cleaning roller 12 is applied with a negative bias voltage of, for example, −3000 V, which is the same as the charging polarity of the toner. That is, an electric field is formed between the rotating cleaning roller 12 and the non-image forming area of the photoconductor 1 in the direction in which the toner on the cleaning roller 12 is discharged toward the photoconductor 1.

Due to the electric field, the toner temporarily collected on the cleaning roller 12 is reattached to the non-image forming area on the photoconductor 1 and returned. The toner redeposited on the photoconductor 1 passes through the discharge lamp 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. At this time, since a positive voltage having a polarity opposite to the charging polarity of the toner is applied to the developing roller 5 as described above, the negative polarity toner redeposited on the photoconductor 1 is applied to the developing roller 5. Is electrostatically transferred to the side of and is collected in the developer in the developing device.

When the image forming operation is continuously performed,
The above-described operation is repeated a predetermined number of times.

As described above, in the image forming apparatus of this example, after the toner image is transferred, the toner remaining on the photoreceptor 1 is temporarily collected by the cleaning member including the cleaning roller 12, and then the collected toner is collected. Is reattached to the image carrier composed of the photoconductor 1, and the reattached toner is collected by the developing device 4. The toner collected in the developing device 4 is reused in the developing device 4. In this way, waste toner can be eliminated. Moreover, it is not necessary to provide a toner conveying pipe for returning the toner collected by the cleaning roller to the developing device.

By applying a bias voltage having a 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 can be electrostatically transferred to the cleaning member. 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 collected toner is applied to the cleaning member to collect the toner collected on the cleaning member on the image carrier. It is possible to electrostatically transfer the collected toner to the image carrier, and thus the collected toner can be redeposited to the image carrier, and the redeposited toner can be collected to the developing device.

Further, in the example of this image forming apparatus, the toner collected by the cleaning roller 12 re-adheres to the non-image forming area near the rear end of the image forming area on the photoconductor 1, so the re-adhered toner. Therefore, not only the electrostatic latent image at the time of the image forming operation described above but also the electrostatic latent image formed next is not affected. The toner is redeposited on the surface portion of the photoconductor 1 that does not affect the formation of the next latent image. In any of the electrostatic latent images, the toner from the cleaning roller 12 redeposits on the surface portion of the photoconductor that is formed on the photoconductor without being disturbed by the redeposition toner. The cleaning roller 1 is provided at the rear of the image forming area.
It is also possible to re-adhere the toner from 2.

Further, in the image forming apparatus of this embodiment, when the transfer residual toner T'on the photosensitive member is collected by the cleaning roller 12 as shown in FIG. 2, the cleaning roller 12 operates as described above. The rotation direction of the cleaning roller 12 is set so that the cleaning roller 12 moves in the direction (counter direction) opposite to the moving direction of the photosensitive body 1 in the nip region N that is in pressure contact with the photosensitive body 1. The recovery operation of the transfer residual toner is completed by the rotation of less than one rotation of 12. In the nip area N, the toner T ′
Is triboelectrically charged by contact with the cleaning roller 12 so as to have a predetermined charge polarity at the time of development, but it is difficult to charge all the toner T'to this polarity, and in some cases, positive toner or charge is used. There is also a toner whose amount is almost zero V.

Therefore, if the cleaning roller 12
2, the cleaning roller 12 is rotated in a direction in which the cleaning roller 12 and the photoconductor 1 move in the same direction in the nip region N with the photoconductor 1, as shown in FIG. If the collected toner T ″ is present on the roller 12 and the toner T ″ remains positively charged or its charge amount is zero, the cleaning roller 12 has the same polarity. Since the positive voltage is applied, the positive polarity toner T ″ is electrostatically attracted toward the photoconductor 1 and adheres to the surface of the photoconductor 1. In this case, the cleaning of the photoconductor 1 is performed. Defects occur, and the toner image that is subsequently formed has background stains.

In order to eliminate such a problem, in this example, the rotation directions of the cleaning roller 12 and the rotation direction of the cleaning roller 12 are set so as to rotate in the counter direction with respect to the rotation direction of the photoconductor 1. At this time, if the cleaning roller 12 is rotated once or more to collect the toner from the photoconductor 1, if the toner T ″ having a positive polarity is present in the toner collected by the cleaning roller 12, the toner T ″ is exposed. Adhesion onto the body 1 causes poor cleaning of the photoconductor 1. Therefore, in this example, the toner collecting operation from the photoconductor 1 to the cleaning roller 12 is completed during the rotation of the cleaning roller 12 for less than one rotation. I am letting you.

When the toner collected on the cleaning roller 12 is reattached to the photosensitive member 1, the cleaning roller 1
2 may be rotated in any direction, but in this example, in the nip region N with the photoconductor 1, the cleaning roller 1
The rotation direction of the cleaning roller 12 is controlled so that 2 and the photoconductor 1 rotate in the same direction (the direction of the chain line arrow in FIG. 2), and the rotation speed thereof is higher than that during toner recovery.
The toner is reattached to the photoconductor 1 in a short time.

Here, in the developing device 4 shown in FIG. 1, the two-component developer D is used as described above, and the developer is the peripheral surface of the developing roller 5. It is carried while being carried by. Then, the developer conveyed on the developing roller 5 is conveyed to the developing section 6 while its thickness is regulated by the developer regulating member 15, and the toner in the conveyed developer is the photoreceptor 1. It is used to visualize the electrostatic latent image formed above.

After the electrostatic latent image is visualized as described above, the toner image is transferred as described above, and the residual toner after the transfer is temporarily collected by the cleaning roller 12, and the photoreceptor 1 However, if the re-adhered toner contains paper dust and is collected by the developing device 4 and enters the same, for example, the developing roller 5
Paper dust is clogged between the developer and the developer regulating member 15, and white streaks (image loss in the circumferential direction of the photoconductor) occur on the image.
The image quality is poor. Even when a one-component developer having no carrier is used as the developer, if paper powder is mixed into the one-component toner, such white streaks occur and the image quality deteriorates.

Therefore, in the image forming apparatus of this example,
A paper dust removing unit that removes the paper dust mixed in the collected toner to the cleaning roller 12, which is one example of the configuration of the cleaning member, is provided outside the cleaning roller 12. In the illustrated example, as the paper dust removing means, the brush 16 whose tip contacts the peripheral surface of the cleaning roller 12
Is used.

Each end of the cleaning roller 12 in the longitudinal direction of the roller shaft is rotatably supported by the cleaning case 17, and the cleaning roller 12 has the photosensitive member 1.
It is stored in the cleaning case 17 except for the portion facing the. A brush mounting bracket 18 is fixed to the cleaning case 17, and a base end portion of the brush 16 is fixedly mounted on a support plate 19 fixed to the bracket 18. The tip of the brush on the free end side of the brush 16 is in contact with the peripheral surface of the cleaning roller 12.

In order to collect the transfer residual toner on the photosensitive member 1 on the cleaning roller 12, the brush 16 scrapes off and removes the paper powder mixed in the toner while the roller 12 rotates. Since the paper dust is thus removed before going to the developing device 4, it is possible to prevent the paper dust from entering the developing device 4. As a result, it is possible to prevent the deterioration of the image quality of the toner image due to the paper dust. The paper dust 20 removed by the brush 16 is stored in the cleaning case 17.

Since the toner on the cleaning roller 12 is electrostatically attached to the cleaning roller 12 when the toner is collected, it is possible to prevent the toner from being scraped off by the brush 16. Cleaning roller 12
When the above-mentioned collected toner is re-attached to the photoconductor 1, by applying a voltage having the same polarity as the charging polarity of the toner to the cleaning roller 12, when the toner easily separates from the cleaning roller 12, The brush 16 may be separated from the cleaning roller 12 only at this time. The brush 16 is supported so as to be able to come into contact with and separate from the cleaning roller 12, and the brush 16 is brought into contact with the cleaning roller 12 to remove the paper dust only when the toner is collected from the photoconductor 1 to the cleaning roller 12. This configuration can also be applied to the brush of each embodiment described later.

Further, by lowering the planting density of the brush 16, it is possible to prevent the problem that the brush 16 scrapes off the toner on the cleaning roller 12. Even if the brush 16 is provided in a rough state as described above, since the size of paper dust is usually larger than that of toner, the brush 1
6, it is possible to remove only paper dust from the cleaning roller 12.

As shown in FIG. 3, the tip of the brush 16A may be brought into contact with the rotation direction of the cleaning roller 12 when the residual transfer toner is collected from the photoconductor 1 in the counter direction. Also in this case, the cleaning case 17
A brush mounting bracket 18A is fixed to the bracket, and a base end portion of the brush 16A is fixed to a support plate 19A fixed to the bracket 18A. Other configurations are
There is no difference from Figure 1.

By using a brush 16A that comes into contact with the rotation direction of the cleaning roller 12 in the counter direction as the brush, the paper dust 20 can be removed from the peripheral surface of the cleaning roller 12 while scooping it up and away. Therefore, it is possible to make it difficult for the paper dust 20 to stay at the tip of the brush. Thereby, the removability of paper dust can be improved.

In the above example, the brush is used as the paper dust removing means, but the paper dust removing means shown in FIG. 4 may be used instead. This paper dust removing means has a fan 22 for generating an air flow for sucking and removing the paper dust, and a paper dust removing filter 21 provided in the air flow path from the cleaning roller 12 to the fan 22. It comprises a paper dust suction / removal device 30. Case 2 for storing the cleaning roller 12 while leaving the roller portion in contact with the photoconductor 1
3, a filter case 24 with a filter 21 attached
However, it is detachably fixed by, for example, a screw 25. Other configurations are the same as those in FIG.

When the fan 22 is rotated by a rotation driving means (not shown), a suctioned air flow is formed from the cleaning roller 12 toward the fan 22, and the paper dust 20 on the cleaning roller 12 rides on this air flow. Away from the paper dust and fly toward the paper dust removing filter 21.
The paper dust 20 is removed by the paper dust removing filter 21, and the paper dust receiving portion 2 of the filter case 24 is removed.
It falls to 4a and is stored here.

While the paper dust 20 is separated from the cleaning roller 12, when the transfer residual toner is collected from the photoconductor 1 to the cleaning roller 12, the cleaning roller 12 is removed.
Since the upper transfer residual toner T ′ is electrostatically attracted to the cleaning roller 12, it is possible to prevent the toner from separating from the cleaning roller 12. When the toner on the cleaning roller 12 is redeposited on the photoconductor 1, a voltage of the same polarity is applied to the cleaning roller 12 and the toner is easily separated from the cleaning roller 12 during this period. Alternatively, the operation of the fan 22 may be stopped.

As described above, as the paper dust removing means, FIG.
By using the paper dust suction / removal device 30 shown in FIG. 1, it is possible to remove only the paper dust without affecting the toner while the toner is held by the cleaning roller 12, and the toner is removed from the case. It can be more reliably prevented from scattering. In addition, as shown in FIG.
If it is configured to be detachable, the paper dust 20 can be easily removed and the filter 21 can be easily replaced.

As shown in FIGS. 1 and 3, in the configuration using the brushes 16 and 16A as the paper dust removing means, no drive means for achieving the paper dust removal is required,
The configuration can be simplified and the cost of the image forming apparatus can be reduced.

On the other hand, as the paper dust removing means, it is possible to use the brush shown in FIG. 1 or 3 and the paper dust suction removing device shown in FIG. 4 together. For example, FIG.
As shown in FIG. 6, a brush 16B as a paper dust removing means, the tip of which abuts against the cleaning roller 12 to scrape away the paper dust.
And a fan 2 for generating an air flow for sucking and removing paper dust
2 and the paper dust removing filter 21 provided in the air flow path from the cleaning roller 12 to the fan 22.
The paper dust suction / removal device 30 having the above is used. Other configurations in FIG. 5 are the same as those in FIG.

In the example of FIG. 5, the removability of paper dust can be greatly improved. Further, also in the case of this example, if the tip portion of the brush 16B is brought into contact with the rotation direction of the cleaning roller 12 when collecting the transfer residual toner from the photoconductor 1 in the counter direction, as described above. In addition, since the paper dust can be scooped up and separated from each other, the paper dust is less likely to be collected at the end of the brush, and the paper dust removability can be improved.

In the embodiment shown in FIG. 1, when the brush 16 is insulative, the above-mentioned voltage is applied to the cleaning roller 12, so that the electric charge is injected into the brush 16. The brush may be charged up. While the brush 16 charges up, it will eventually discharge,
Electrical noise is generated. When such noise occurs, the control unit equipped in the image forming apparatus is likely to malfunction.

Therefore, if the brush 16 is a conductive brush, it is difficult for the brush to be charged up, and it is possible to prevent generation of noise due to discharge. This can prevent the control unit from malfunctioning. Further, by making the brush conductive, unnecessary static electricity is not applied to the toner, so that it is possible to make it difficult for the toner to adhere to the brush 16 when removing paper dust. 3 and 5
Similarly, in the embodiment shown in FIG.
By making 6B conductive, it is possible to prevent malfunction of the control means and make it difficult for toner to adhere to the brush. In addition, the conductivity referred to here includes that which is generally referred to as medium resistance, and means the conductivity having a volume resistivity of 10 ^{7 to} 10 ⁸ Ωcm or less. The same applies to the following description.

In the embodiment shown in FIG. 1, at the time of collecting the transfer residual toner, a bias voltage having a polarity opposite to the charging polarity of the toner at the time of development is applied to the cleaning roller 12 by the power source E ₄ to remove the transfer residual toner. At the time of re-adhesion, a bias voltage having the same polarity as the charging polarity of the toner at the time of development is applied by the power source E ₅ , and the power source E ₄ , E ₅ together with the cleaning roller 12 make the brush conductive. When 16 is connected, the brush 16 can be kept at the same potential as the cleaning roller 12 both when the transfer residual toner is collected and when the collected toner is reattached.

In this example, specifically, the conductive brush 1
In FIG. 6, a positive bias voltage is applied when the toner is collected from the photoconductor 1, and a negative bias voltage is applied by switching the voltage polarity when the toner is reattached to the photoconductor. As a result, the brush 16 and the cleaning roller 12 have the same potential, and it is possible to prevent the brush 16 itself from being charged up. Further, it is possible to make it difficult to electrostatically move the toner toward the brush 16. The reason is that an electric field that allows the toner on the cleaning roller 12 to be attracted to the brush 16 is not formed.

By using, as the conductive brush, a brush to which a voltage which makes the cleaning member have the same potential is applied,
Only the paper dust can be effectively scraped off, and the transfer residual toner can be more reliably prevented from electrostatically adhering to the brush. In addition to this point, it is possible to prevent the toner from being slightly charged up due to no charge being injected into the toner, and to stabilize the charge amount of the toner. As a result, the collectability of the toner in the developing device can be improved. The brush 1 shown in FIGS. 3 and 5 is used.
In 6A and 16B as well, by applying a voltage to the same potential as the cleaning roller 12, the above-described function can be achieved similarly.

The above-mentioned structure has the brushes 16, 16A, 1
6B is provided with voltage applying means for applying a voltage for making the brush the same potential as the cleaning member,
In the illustrated example, power supplies E ₄ and E ₅ for the cleaning roller 12 are used as the voltage applying means.

On the other hand, the brushes 16, 16A, 16B
On the other hand, it is also possible to provide a voltage applying means (not shown) for applying a voltage of the same polarity as the toner collected on the cleaning member, in this example, a negative voltage. That is, in each of the configurations shown in FIGS. 1 to 5, when the transfer residual toner is collected from the photosensitive member 1 to the cleaning roller 12, when the voltage of +200 V is applied to the cleaning roller 12 as described above, each brush 16 is applied. , 16A, 16B are applied with a voltage of, for example, −100 V having the same polarity as the collected toner by a power source (not shown). Between the cleaning roller 12 and the brushes 16, 16A, 16B, the collected toner on the cleaning roller 12 forms an electric field attracted on the cleaning roller 12, and the brushes 16, 16A, 16B have the same amount as the collected toner. A polarity voltage is applied. This surely prevents the collected toner from migrating to the brush side, and also prevents the toner from being inverted by injecting a charge having a predetermined polarity, in this example, a polarity opposite to the negative polarity. it can.

When the toner collected on the cleaning roller 12 is reattached to the photoconductor 1, a voltage having the same polarity as that of the toner is applied to the cleaning roller 12, so that the brushes 16, 16A, 16B are A voltage higher than the voltage applied to the cleaning roller 12 and having the same polarity as the charging polarity of the toner is applied. For example, when the toner is redeposited, the cleaning roller 12 has a −
When a voltage of 3000 V is applied, the brush 1
A voltage of -3300 V is applied to 6, 16A and 16B by a power source (not shown). As a result, even when toner is reattached to the photoconductor 1, the cleaning roller 12
The upper toner is not electrostatically attracted to the brushes 16, 16A, 16B side, the toner is securely electrostatically held by the cleaning roller 12, and the positive charge is injected into the toner. The polarity does not reverse. In this way, the toner redeposited on the photoconductor 1 can be reliably collected in the developing device 4, and the positively charged toner can be prevented from entering the developing device 4.

In the case of this example, in order to prevent a large current from flowing through the brushes 16, 16A, 16B, especially when the toner is reattached to the photoconductor 1, the brush 1
It is desirable that 6, 16A and 16B be made of a material having a volume resistivity of about 10 ^{7 to} 10 ⁸ Ωcm.

According to the respective configurations described above, it is possible to remove foreign matters other than the paper dust mixed in the toner collected by the cleaning roller 12.

In the present invention, after charging the image bearing member, an electrostatic latent image is formed by a portion which is not irradiated with light, and a toner charged to a polarity opposite to the polarity of the potential is attached to perform development. It can also be applied to a positive / positive developing type image forming apparatus.

In addition to the roller-shaped cleaning member, an image forming apparatus using an endless belt or the like, or an image forming apparatus using an endless belt-shaped member other than a drum-shaped image carrier. Can also be applied.

Further, it is also applicable to an image forming apparatus of a type in which an intermediate transfer member is used as a recording medium, a toner image is transferred from the image carrier to the intermediate transfer member, and then this is transferred to a transfer material.

[0068]

According to the image forming apparatus of the first aspect, the paper dust mixed in the transfer residual toner collected by the cleaning member can be removed before being conveyed to the developing device. It is possible to make it difficult for the powder to be mixed into the developing device, and thus it is possible to prevent the occurrence of image deterioration of the toner image due to the paper powder.

According to the image forming apparatus of the second aspect,
Since no drive means is required to remove paper dust,
The configuration of the image forming apparatus can be simplified and the cost of the image forming apparatus can be reduced.

According to the image forming apparatus of claim 3,
It is possible to effectively remove the paper powder without affecting the toner collected on the cleaning member and prevent the toner from scattering.

According to the image forming apparatus of the fourth aspect,
By using the brush and the paper dust suction / removal device together, the removability of the paper dust mixed in the collected toner to the cleaning member can be greatly improved.

According to the image forming apparatus of the fifth aspect,
At the time of removing the paper dust, the paper dust is less likely to be collected at the end portion of the brush, so that the paper dust removing property can be further improved.

According to the image forming apparatus of the sixth aspect,
At the time of removing the paper dust, it is possible to prevent toner on the cleaning member from adhering to the brush, and it is possible to prevent the brush from charging up, so that it is possible to prevent electrical noise due to discharge from occurring easily, and the control unit. It is possible to prevent the malfunction of the.

According to the image forming apparatus of claim 7,
When removing the cleaning member, it is possible to make it difficult for the toner on the cleaning member to adhere to the brush, and
Since charges are not injected into the toner on the cleaning member and the charge amount of the toner can be stabilized, the toner recoverability on the developing device side can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention, in which hatching is omitted for a portion showing a cross section.

FIG. 2 is an enlarged schematic view of a frictional contact portion between the photoconductor and the cleaning roller, for explaining that the toner charging polarities are made uniform;

FIG. 3 is a schematic configuration diagram of a main part of an embodiment in which a brush that comes into contact with a cleaning roller in a counter direction is used as the brush.

FIG. 4 is a schematic configuration diagram of a main part of an embodiment example in which a paper dust suction / removal device is used as a paper dust remover.

FIG. 5 is a schematic configuration diagram of a main part of an embodiment using a brush and a paper dust suction / removal device as paper dust removing means.

[Explanation of symbols]

 4 Developing Device 8 Transfer Part 16 Brush 16A Brush 16B Brush 20 Paper Powder 21 Paper Powder Removal Filter 22 Fan 30 Paper Powder Suction Removal Device T ′ Toner

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

Claims (7)

[Claims] 1. An electrostatic latent image formed on a rotationally driven image carrier is visualized as a toner image by a developing device, the toner image is transferred to a recording medium at a transfer portion, and after the toner image is transferred. The toner remaining on the image bearing member is temporarily collected by the cleaning member, and then the collected toner is re-attached to the surface portion of the image bearing member that does not affect the formation of the next latent image. An image forming apparatus that collects the re-adhered toner by a developing device, a paper dust removing unit that removes the paper dust mixed in the toner collected by the cleaning member to the outside of the cleaning member. Forming equipment. 2. The image forming apparatus according to claim 1, wherein a brush whose front end contacts the cleaning member is used as the paper dust removing unit. 3. A paper dust removing means, which has a fan for generating an air flow for sucking and removing paper dust and a paper dust removing filter provided in a path of the air flow from the cleaning member to the fan. The image forming apparatus according to claim 1, wherein a suction removing device is used. 4. As a paper dust removing means, a brush whose front end contacts a cleaning member to scrape the paper dust, a fan for generating an air flow for sucking and removing the paper dust, and a cleaning member to a fan. The image forming apparatus according to claim 1, wherein a paper dust suction / removal device having a paper dust removal filter provided in a path of the air flow is used. 5. The image forming apparatus according to claim 2, wherein the tip of the brush is in contact with the rotation direction of the cleaning member in the counter direction. 6. The image forming apparatus according to claim 2, wherein the brush is provided with a voltage applying unit that applies a voltage that brings the brush to the same potential as the cleaning member. 7. The image forming apparatus according to claim 2, wherein the brush is provided with voltage applying means for applying a voltage having the same polarity as that of the toner collected by the cleaning member.