JP3472028B2 - Image forming device - Google Patents

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 electrostatically collects by a cleaning member to clean 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 the toner to be discarded can be eliminated, but also the cleaning device can be omitted, and the image forming system can be simplified and the cost of the image forming device can be reduced. However, at present, it is difficult to set the transfer rate of the toner image to 100%, and there is a problem in terms of reliability.

Therefore, as a second best measure, the transfer residual toner remaining on the surface of the image carrier after the transfer of the toner image is electrostatically adhered to the cleaning member and collected, and then this recovered toner is collected on the image carrier. There has been proposed a method of reattaching electrostatically, collecting by a developing device, and reusing this (see, for example, Japanese Patent Publication No. 61-30274). After the toner image is transferred, the transfer residual toner remaining and attached on the image carrier is temporarily collected by the cleaning member, and the collected toner is affected by the formation of the next electrostatic latent image on the image carrier. The toner re-adhered to the non-existing surface portion and further re-adhered to the surface of the image carrier is 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.

In this type of image forming apparatus, paying attention to the transfer residual toner on the image carrier, the adhered amount may be non-uniform in the axial direction of the image carrier. In this way, the transfer residual toner collected on the surface of the cleaning member is also non-uniform in the amount of adhesion in the axial direction of the cleaning member, and
In some cases, the toner adhesion amount may become excessively large.
For such a large amount of toner, it becomes impossible to re-adhere all the toner to the image carrier,
Part of the toner remains on the cleaning member. If a large amount of toner remains on the surface of the cleaning member in this way, when such a cleaning member collects transfer residual toner on the image bearing member, the toner recovery efficiency at the part where a large amount of toner remains will decrease. As a result, the cleaning efficiency for the image bearing member is lowered, and the toner image formed on the image bearing member is liable to cause background stain.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to electrostatically collect transfer residual toner on a cleaning member, electrostatically re-adhere the recovered toner to an image carrier, and then re-adhesion. The problem described above in the image forming apparatus of the type in which the collected toner is electrostatically collected by the developing device is solved, and the adhesion amount of the collected toner on the cleaning member is non-uniform in the axial direction. An object of the present invention is to provide an image forming apparatus capable of preventing a partial decrease in collection efficiency when collecting toner.

[0008]

In order to achieve the above object, the present invention is directed to an image carrier which is driven to rotate, a latent image forming means for forming an electrostatic latent image on the carrier, and an electrostatic latent image forming means. A developing device that visualizes the latent image as a toner image, a transfer device that transfers the toner image on the image carrier to a recording medium, and a transfer residual toner that is electrostatically temporarily collected while rotating, and then A cleaning member that electrostatically redeposits the collected toner on a surface portion of the image carrier that does not affect the formation of the next electrostatic latent image. When a voltage having a polarity opposite to the charge polarity of the toner at the time of development is applied to the member and the collected toner is redeposited on the surface of the image carrier, the cleaning member has the same charge polarity as the toner at the time of development. Applying a polar voltage to the image carrier In an image forming apparatus that electrostatically collects toner reattached to the surface in a developing device, a conductive leveling member that smoothes the toner collected in the cleaning member in the axial direction of the cleaning member is attached to the surface of the cleaning member. It is proposed to provide an image forming apparatus characterized by including a voltage applying unit that is provided opposite to the leveling member and applies a voltage having the same polarity as the toner charging polarity at the time of development when the transfer residual toner is collected. Item 1).

In this case, it is advantageous to arrange the leveling member so as to be in pressure contact with the surface of the cleaning member.

In the above structure, the leveling member is
It is also advantageous to face the surface of the cleaning member with a gap (claim 3).

Further, in each of the above-mentioned constitutions, it is advantageous to provide side seals for preventing toner scattering, on both axial sides of the cleaning member and the leveling member (claim 4).

[0012]

[0013]

Further, in each of the above-mentioned constitutions, when the cleaning member is a cleaning member which rotates in the opposite direction at the time of toner collection and at the time of re-adhesion of toner, the leveling member at the time of re-adhesion of toner It is advantageous to provide a leveling member drive means for driving the leveling member so that the leveling member is displaced to a position farther from the cleaning member than the operating position (claim 5).

Further, in each of the above constructions, when the cleaning member is a cleaning member which rotates in the opposite direction during the toner recovery and the toner re-adhesion, the toner leveling portion of the leveling member and the cleaning member are imaged. It is advantageous to provide it within the range of 90 ° from the contact portion with the carrier to the downstream side in the rotation direction of the cleaning member at the time of toner recovery (claim 6).

Further, in each of the above-mentioned constitutions, it is advantageous to control the rotation of the cleaning member so that the cleaning member rotates in the same direction when the toner is collected and when the toner is reattached (Claim 7).

Further, in each of the above constructions, it is advantageous that the leveling member is a leveling blade (claim 8).

Further, in each of the above structures, it is advantageous that the leveling member is a leveling roller (claim 9).

Further, in the above structure, the leveling roller and the cleaning member are moved in the same direction at the facing portion of the leveling roller and the cleaning member in both the toner collecting and the toner re-adhesion. It is advantageous to control the rotation of the leveling roller (claim 10).

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. First, the basic configuration of the image forming apparatus common to the later-described characteristic configuration of the present example and its operation will be clarified.

FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus according to the present invention. In the figure, a drum-shaped photoconductor 1 which is an example of the 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 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 the charging device for uniformly charging the photoconductor 1, a charging device arranged apart from the photoconductor, such as a corona discharger, may be used.

Next, in the exposure section 3, an exposure scanning device (not shown) performs optical writing scanning with, for example, the light-modulated laser beam 11, so that a predetermined electrostatic latent image is formed on the surface of the photoconductor 1. Is formed. Photoconductor 1
The surface potential of the upper part A irradiated with the laser beam 11, that is, the surface potential of the electrostatic latent image is, for example, about −150 V, and the surface potential of the part B not irradiated with the laser beam 11, that is, the background potential of the background portion of the electrostatic latent image is almost equal. 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 includes a developing roller 5 which is an example of a developer carrying and conveying member which is 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 adopted.

The developing roller 5 is driven to rotate counterclockwise in the drawing, and the developer carried on the peripheral surface thereof 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 with respect to the photosensitive member 1.
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 portion 8. After the toner image is transferred, the photoconductor 1 is transferred.
The toner remaining on the photoconductor 1 without being transferred to the transfer paper 16 adheres to the surface of the. Transfer residual toner T ₁
When it reaches the cleaning unit 14, it is temporarily collected on the surface of the cleaning roller 12, which is an example of a cleaning member.

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

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

The cleaning roller 12 shown in FIG.
When the transfer residual toner T 1 on the photoconductor ₁ is collected, the transfer residual toner T ₁ is rotationally driven in the clockwise direction (direction of arrow a) in FIG. 1, that is, in the counter direction with respect to the rotation direction of the photoconductor 1. Rotate while rubbing against the surface of the body 1. The surface of the cleaning roller 12 itself is the photosensitive member 1.
It is pressed against the photoreceptor 1 so that it is elastically deformed by the nip region N as shown in FIG.
Is formed. This nip area N becomes a cleaning area. The width of the nip area N in the circumferential direction of the photoconductor is, for example, about 1 mm, but the width of the nip area N is exaggerated in FIGS. 1 and 2 (FIGS. 13 and 1).
5, FIG. 16, FIG. 19, and FIG. 20 to FIG. 22).

In the nip region N, the transfer residual toner T ₁ having both positive and negative polarities becomes a toner having the same polarity (negative polarity in this example) as the toner at the time of development while being in contact with the cleaning roller 12. 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 made 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.
In a, a polarity opposite to the charging polarity of the toner frictionally charged by the roller 12 (that is, the charging polarity of the toner at the time of development), a positive voltage in this example, for example, +2
A voltage of 00V is applied by the voltage power supply E ₄ . Therefore, the residual toner after the transfer of the toner image which has passed through the transfer portion 8,
That is, the transfer residual toner T ₁ frictionally charged by the cleaning roller 12 is electrostatically attracted to the surface of the cleaning roller 12 to which a positive voltage is applied,
It 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 brought into a cleaning state. In this way, the cleaning roller 12 rotating in contact with the photoconductor 1 is
The transfer residual toner T ₁ on the photoconductor is the cleaning roller 1
A voltage having a polarity (positive polarity in this example) opposite to the charging polarity of the toner at the time of development is applied so that an electrostatically attractable electric field is formed on the surface of No. 2.

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, a toner image on the photoconductor 1 is indicated by an arrow P.
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 is started. 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 trailing edge Z of the image forming area X in the direction of rotation of the photosensitive member passes the charging roller 2, the charging roller 2 is separated from the surface of the photosensitive member 1 at this time. (See 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.

[0039] 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 photoconductor 1 after the toner image is transferred, and electrostatically temporarily collects the transfer residual toner T ₁ to clean the surface of the photoconductor 1. Clean, but then collect the collected toner T ₂ .
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 the voltage power source E ₅ , and the core member 12 a of the cleaning roller 12 has a charging polarity of the toner frictionally charged by the cleaning roller 12, that is, the same polarity as the charging polarity of the toner at the time of development, in this example. A negative voltage of, for example, −3000 V is applied. 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, in the example shown in FIGS. 1 to 11, the cleaning roller 12 rotates in the forward direction (counterclockwise direction in FIG. 1 and indicated by a chained arrow b in FIG. 2) with respect to the photoconductor 1. Shall be driven. As shown in FIG. 9, the toner T ₃ redeposited on the photoconductor 1 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 as shown in FIG. The developing device 4 is reached as shown. At this time, as described above, since the positive polarity voltage opposite to the charging polarity of the toner at the time of development is applied to the developing roller 5, the negative polarity toner T ₃ redeposited on the photoconductor 1 is applied. Are electrostatically transferred to the developing roller 5 side and are collected in the developer in the developing device.

As described above, the cleaning member including the cleaning roller 12 electrostatically and temporarily collects the transfer residual toner T ₁ frictionally charged on its surface while rotating, and then the collected toner. T ₂ is the photoconductor 1
The toner T ₃ re-deposited electrostatically on the surface portion of the image carrier which does not influence the formation of the next electrostatic latent image, and further re-adhered to 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
It is possible to eliminate the waste toner, and it is not necessary to provide a toner conveying 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 again, the cleaning roller 12 has 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.

As a charging device, separated from the photoconductor 1,
For example, when a corona discharger is used, the image forming area X
Even after the trailing edge Z passes through the corona discharger, the discharger can continuously charge the surface of the photoconductor 1 to the same polarity as the charging polarity of the toner (negative polarity in this example). By doing so, the surface portion of the photoconductor 1 carrying the re-adhered toner T ₃ shown in FIG. 9 can be charged to the same polarity as the charging polarity of the toner, for example, −850 V by the corona discharger. The attached toner T ₃ is the developing device 4
When the developing roller 5 is opposed to the developing roller 5, the re-adhered toner T ₃ is applied to the developing roller 5 even if a voltage of −600 V having the same polarity as the toner charging polarity is applied. Can be electrostatically recovered. That is, the voltage applied to the developing roller 5 is
The redeposited toner can be electrostatically collected by the developing device 4 without switching between the developing operation and the collection of the redeposited toner on the developing roller 5.

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 enlarged and shown (the same applies to FIGS. 12 to 14, 19, and 21).

As described above, the toner T ₂ collected on 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 reattachment of the collected toner to the photoconductor 1 can be carried out 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 to the cleaning member a bias voltage having a polarity opposite to the charging polarity of the toner at the time of development, 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, FIG. 7 shows the cleaning roller 12
FIG. 6 shows a state in which the transfer residual toner has been collected to the cleaning roller 12 in the counter direction with respect to the rotation direction of the photoconductor 1, that is, in the photoconductor when the collection is performed, as shown in FIG. At the contact portion with the photosensitive member 1
It is rotationally driven by a control drive means (not shown) in a direction moving in the opposite direction.

On the other hand, FIG. 8 shows a state in which the collected toner T ₂ on the cleaning roller 12 is being reattached to the photoconductor 1, but at the time of such reattachment, as described above, The cleaning roller 12 is rotationally driven in the forward direction with respect to the rotation direction of the photoconductor 1, that is, in the direction in which the cleaning roller 12 moves in the same direction as the photoconductor 1 at the contact portion with the photoconductor 1 by the control driving means. As described above, in this example, the cleaning roller 12 is rotationally driven in the direction opposite to that at the time of toner recovery when reattaching the toner. The cleaning roller rotates in the opposite direction when the toner is collected and when the toner is reattached.

On the other hand, the cleaning roller 12 is
When the toner is collected, the cleaning roller 12 is rotated, for example, as shown in FIG. 6, and after this rotation is completed as shown in FIG. 7, the cleaning roller 12 is also rotated clockwise as shown in FIG. You may let me. As described above, even when the cleaning roller 12 is rotated in the same direction at the time of collecting toner and at the time of re-adhering toner, the photoconductor 1
It is possible to collect the toner from the toner and reattach the toner to the photoconductor 1. FIG. 12 shows an intermediate state of the toner re-adhesion process, and the re-adhesion toner is conveyed toward the developing device 4 as shown in FIG.

As described above, when the toner is collected from the photoconductor 1 and when the toner is reattached to the photoconductor 1, the cleaning rollers 12 may be rotated in the opposite directions or may be rotated in the same direction. Alternatively, the rotation direction of the cleaning roller 12 at that time can be appropriately set,
The rotation direction is not necessarily limited to that shown in FIGS.

However, in any case, when the transfer roller residual toner on the photosensitive member 1 is collected by the cleaning roller 12, the cleaning roller 12 is rotated once less than one rotation.
It is desirable to control the rotation of the cleaning roller 12 so as to complete the toner collection operation once. Moreover, at the time of collecting the toner, it is preferable that the cleaning roller 12 is rotationally driven in the counter direction with respect to the photoconductor 1 as in the example shown in FIGS. The reason is as follows.

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 is charged with a polarity opposite to that of the toner during development. The mixed toner (called abnormal polarity toner) is mixed, and in this example, the abnormal polarity toner is made to have the same polarity as the charging polarity of the toner at the time of development by frictional charging with the cleaning roller 12. However, it is difficult to completely align the charging polarities of the transfer residual toners existing in the nip area N shown in FIG. 2, and in some cases, the toners having the charging polarities opposite to the charging polarities of the toners at the time of development, that is, The abnormal polarity toner may exist. When the toner on the photoconductor 1 is collected by the cleaning roller 12 during a normal image forming operation, a voltage having a polarity opposite to the charging polarity of the toner at the time of development is applied to the cleaning roller 12 as described above, and The toner having the charging polarity is electrostatically transferred to the cleaning roller 12 and is collected by the roller 12, but at this time, the toner having the polarity opposite to the charging polarity at the time of development (abnormal The polar toner) also receives the mechanical scraping force from the cleaning roller 12,
It 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, as shown in FIG. 2, when the transfer residual toner T ₁ is collected from the photoconductor 1 to the cleaning roller 12 in the normal image forming operation, the contact area between the photoconductor 1 and the cleaning roller 12, that is, , The rotation direction of the cleaning roller 12 is controlled so that they move in opposite directions (counter direction) in the nip region N where they come into pressure contact, and when the cleaning roller 12 rotates less than one rotation, the residual toner T ₁ of the on body 1 so as to recover the cleaning roller 12, by controlling the rotation of the cleaning roller 12, the toner T _2, which is collected by the cleaning roller 12 is, in its toner recovery operation, again photoreceptor There is no contact with 1. Moreover, it is possible to prevent the abnormal polarity toner collected on the cleaning roller 12 from being electrostatically transferred to the surface of the photoconductor 1 after cleaning during the toner collecting operation.

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

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

When the cleaning roller 12 is rotated in the forward direction with respect to the photosensitive member 1, the cleaning roller 1
2 may be directly rotationally driven by the control drive means,
Instead of applying such a driving force to the cleaning roller 12, the cleaning roller 12 may be rotationally driven by being driven by the rotation of the photoconductor 1.

The above is the basic configuration of the image forming apparatus of this example and its operation. In such an image forming apparatus, attention is paid to the transfer residual toner on the photoconductor 1, and the amount of adhesion is in the photoconductor axial direction. It may become uneven. For example, as shown in FIG. 14, the transfer residual toner on the photoconductor 1 may increase in the E portion and the F portion. When there is a wide line toner image having a high density in the circumferential direction of the photoconductor 1, the amount of the transfer residual toner is large in the E and F portions corresponding to the line toner image.

As described above, when the adhered amount of the transfer residual toner on the photoconductor 1 becomes non-uniform in the axial direction, the adhered amount of the toner collected on the cleaning roller 12 also becomes non-uniform. For example, as shown in FIG. 14, the adhered amount of the collected toner T ₂ partially increases in the portions corresponding to the E portion and the F portion on the photoconductor 1.

In this type of conventional image forming apparatus,
As for the toner having a large adhered amount on the cleaning roller 12, all of the toner cannot be re-adhered to the photoconductor 1 and a part of the toner remains on the cleaning roller 12, and the accumulated amount of the toner remains. It was sometimes too large. As described above, when the remaining amount of the collected toner on the cleaning roller 12 becomes large even if it is partial, when the cleaning roller 12 collects the transfer residual toner on the photoconductor 1, the toner recovery efficiency (cleaning efficiency)
Is partially reduced. Thus, the background stain is generated on the photoconductor.

Therefore, in the image forming apparatus of this example,
A leveling member that smoothes the toner collected by the cleaning member in the axial direction of the cleaning member is placed opposite to the surface of the cleaning member. A reference numeral 18 in FIG. 1 is a leveling blade which is an example of the configuration of the leveling member. The leveling blade 18 is formed in a flat plate shape, faces the cleaning member composed of the cleaning roller 12, and extends in parallel with the member and in the axial direction thereof. The leveling blade 18 is made of, for example, an elastic body such as rubber or a metal such as stainless steel. 2 to 12, illustration of the leveling member is omitted.

The leveling blade 18 has its abdomen shown in FIG.
As shown in FIG. 5, the cleaning roller 12 is placed so as to be in pressure contact with the surface of the cleaning roller 12. Leveling blade 18
If is composed of elastic blades,
It is also possible to press the cleaning roller in a bent state with a predetermined pressing force.

The leveling blade 18, as schematically shown in FIG. 13, has the cleaning roller 12 rotate in the counter direction (the direction of the arrow in the figure) with respect to the rotating direction of the photosensitive member 1 to expose the photosensitive member 1. when recovering the residual toner T ₁ of the on body 1, is homogenized by becoming the collected toner T ₂ to be conveyed is supported on the cleaning roller 12 in the direction of rotation in the axial direction. As shown in FIG. 14, when the adhesion amount of the collected toner T ₂ is non-uniform in the axial direction of the cleaning roller 12, the leveling blade 18 causes the collected toner T ₂ to move.
₂ is a wedge-shaped portion (FIG. 13) between the leveling blade 18 and the cleaning roller 12, and is leveled so as to be uniform along the axial direction of the roller 12. Even if the leveling blade 18 is brought into pressure contact with the cleaning roller 12 not at the abdomen but at the leading edge portion, the collected toner can be evened out in the same manner.

Since the collected toner T ₂ is leveled in the axial direction of the cleaning roller 12 in this manner, when the toner is reattached to the photosensitive member 1 as described above, the toner is entirely spread. It can be efficiently reattached to the surface of the photoconductor 1. Since the re-adhesion efficiency of the toner is increased in this manner, it is possible to prevent a large amount of toner from partially remaining on the surface of the cleaning roller 12. Therefore, the cleaning roller 12 can efficiently collect the transfer residual toner on the photoconductor 1, and
It is possible to improve the cleaning efficiency, prevent the background stain on the photoconductor 1, and form a high quality toner image.

As in the above example, as the leveling member,
By using the low-priced leveling blade 18 with a simple structure, it is possible to suppress an increase in the cost of the image forming apparatus, but as described later, the shape of the leveling member is not limited to the blade. .

If, for example, a leveling member composed of the leveling blade 18 is placed so as to be in pressure contact with the surface of the cleaning member composed of the cleaning roller 12, the collected toner on the cleaning roller 12 is Since the leveling blade 18 directly receives the leveling force, it is possible to enhance the leveling effect of the collected toner. The collected toner on the cleaning roller 12 passes between the surface of the cleaning roller 12 and the leveling blade that is pressed against the cleaning roller 12 as the cleaning roller 12 rotates.

On the other hand, for example, a leveling member composed of the leveling blade 18 may be opposed to the surface of the cleaning member composed of the cleaning roller 12 with a gap G as shown in FIG. Break-in blade 1
The leveling blade 18 is placed so as to face the cleaning roller 12 at the tip abdomen with a gap of, for example, about 0.05 mm.

Even if such a construction is adopted, the collected toner can be evenly distributed in the axial direction of the cleaning roller. In the case of this configuration example, since the leveling member does not directly contact the cleaning member, it is possible to prevent early wear of the contact surfaces of the cleaning member and the leveling member, and it is possible to extend the service life of both, The break-in function and the cleaning function can be stably maintained for a long period of time. Further, the rotational load of the cleaning member composed of the cleaning roller 12 is not increased.

By positioning the leveling member with respect to the cleaning member by the gap setting member, the gap G shown in FIG. 16 can be set accurately and accurately.

As shown in FIG. 17, an end portion of the core member 12a of the cleaning roller 12 is rotatably supported on the side wall 17a of the cleaning case 17 via a bearing 19. Although not shown, the other end of the core member 12a of the cleaning roller 12 is also rotatably supported by the other side wall of the cleaning case via a bearing.

A gap setting member 21 is relatively rotatably fitted in the core member 12a, and the member 21 is fixedly held on the cleaning case 17 side. Although not shown, a similar gap setting member is also provided on the side of the other cleaning case. Gap setting member 2
The inner surfaces of both ends of the leveling blade 18 contact one and the other gap setting member, and the leveling blade 18 opens a gap G with respect to the cleaning roller 12 by the gap setting member 21 and another gap setting member. Are positioned so as to face each other. By adopting such a configuration, the gap G between the leveling member and the cleaning member can be accurately set to be constant in the axial direction of the cleaning roller 12.

In each of the above-mentioned configurations, as shown in FIG. 18, the toner scattering prevention side seals 23 (on the both axial sides of the cleaning member composed of the cleaning roller 12 and the leveling member composed of the leveling blade 18). If only one side is shown), it is possible to prevent toner from scattering from both ends.

As shown in the figure, the cleaning roller 1
A side seal 23 is fitted into the second core member 12a so as to be relatively rotatable, and the seal 23 is partially fixed to the cleaning case 17 side. The side seal 23 is in contact with the end portion of the cleaning roller 12 and the side end portion of the leveling blade 18, and covers the portion located at this side end portion. Similarly, the other end of the cleaning roller 12 is also closed by a side seal (not shown). The side seal 23 is preferably made of an elastic body such as foam.

As shown in FIG. 14, the toner T ₂ collected on the cleaning roller 12 is moved in the axial direction of the roller, and is smoothed out. At this time, the toner T ₂ moved outward in the axial direction. However, there is a risk that the cleaning roller 12 and the leveling blade 18 shown in FIG. When such a toner drop occurs, the inside of the cleaning case 17 or the vicinity thereof is soiled with the toner. By providing the side seal 23, it is possible to prevent the toner from scattering from the end portion side, so that it is possible to prevent the inside of the cleaning case 17 or the vicinity of the cleaning case from being contaminated with the scattered toner.

As the material of the leveling member in each of the above-described configurations, various materials including, for example, an insulating material can be adopted. If the leveling member is made of an insulating material,
Electric charges are accumulated in this, and finally, the cleaning roller 12
There is a case where a discharge is generated between the control unit and the control unit and the control unit of the image forming apparatus malfunctions. In such a case, the leveling member may be a conductive leveling member. For example, the leveling blade 18 is made of a conductive rubber or metal to prevent electric charges from accumulating in the leveling blade 18. As a result, discharge between the leveling blade 18 and the cleaning roller 12 can be prevented, and malfunction of the control unit can be prevented. The leveling blade 18 is made of a conductive material, and further,
The grounding state can further enhance the effect of preventing the discharge.

Here, in FIG. 1, the cleaning unit 1
4 (nip portion N shown in FIG. 2), the transfer residual toner is triboelectrically charged to have the same charging polarity as the toner at the time of development, but as described above, the toner has the same charging polarity. Some toner cannot be used, and such abnormal polarity toner (positively charged polarity toner in this example)
The cleaning roller 12 may be collected as it is. When the toner is reattached, the cleaning roller 12
Since a negative voltage is applied to the cleaning roller 1, the abnormal polarity toner does not electrostatically transfer to the photoconductor.
2 remains on top. Then, the remaining abnormal polarity toner may be transferred from the cleaning roller to which a positive voltage is applied and adhere to the photoconductor at the time of collecting the next toner, and may cause scumming on the photoconductor.

Therefore, in each of the above-mentioned configurations, a bias voltage having the same polarity as the toner charging polarity during development is applied to the leveling member including the leveling blade 18 when the transfer residual toner on the photoconductor 1 is collected. When a voltage applying means for applying the voltage is provided and the charge having the charged polarity of the toner at the time of development is injected into the abnormal polarity toner on the cleaning roller 12 by the leveling member to which the voltage is applied, the collected toner on the cleaning roller 12 is removed. The charging polarities can all be made equal to the charging polarities at the time of development, and the toner can be surely reattached to the photoconductor 1. by this,
It is possible to prevent the background stain on the image.
Such a configuration can be used particularly advantageously when the leveling member is made of a conductive material.

In addition, when a bias voltage of the above polarity (negative polarity in this example) is applied to the leveling member including the leveling blade 18 and the like, the toner has a charging polarity during development (negative polarity in this example). The toner on the cleaning roller 12 is electrically repelled by the blade 18, so that the toner particles easily diffuse with each other, and the leveling effect by the leveling blade can be enhanced. Further, it is possible to prevent the toner having the original charging polarity from being electrostatically attached to the leveling blade.

Specifically, as shown in FIG. 1, when the transfer residual toner on the photoconductor 1 is collected by the cleaning roller 12, a positive bias voltage (for example, +200 V) is applied by the power source E ₄ . reattachment during the recovery toner is negative bias voltage by the power source E ₅ (e.g., -300
0 V) is applied to each of them, and in response to this, a voltage having a negative polarity of, for example, −100 V is applied to the leveling blade 18 by the voltage applying unit composed of the power source E ₆ when the transfer residual toner is collected. Is applied. by this,
Even if the collected toner on the cleaning roller 12 contains a positive polarity toner having a different polarity, a negative charge can be injected into the positive polarity toner to change it to a negative polarity.

When the switch S ₂ is switched to apply a voltage of, for example, -3000V to the cleaning roller 12 to start the toner re-adhesion operation, a voltage of -100V is applied to the leveling blade 18. If left as it is, the leveling blade 18 will be on the plus side of the cleaning roller 12, and the minus toner on the cleaning roller 12 will adhere to the leveling member 18. Therefore, at the same time as the switch S ₂ is switched, the switch S ₄ is switched so that a negative voltage of, for example, −3300V is applied to the blade 18 by the power source E ₇ when the collected toner is reattached.

At the time of re-adhesion of toner, the voltage applied to one cleaning roller 12 is -3000 V, and the voltage applied to the other leveling blade 18 is -33 V.
Since it is 00V, the leveling blade 18 has a larger negative polarity potential, and during the re-adhesion process of the collected toner, the negative polarity charged toner which is the original polarity toner carried on the cleaning roller 12 is Break-in blade 1
8 can be effectively prevented from being electrostatically adhered to and left unattended by the leveling blade.

By the way, for example, the cleaning roller 12
When the cleaning member composed of the cleaning members is a cleaning member that rotates in the opposite directions as described above during the toner recovery and the toner re-adhesion, for example, as shown in FIG. The transfer residual toner is collected by the cleaning roller 12 by rotating in the clockwise direction (arrow direction), and then the cleaning roller 12 is rotated in the counterclockwise direction in the figure, and the collected toner is reattached to the photoconductor 1. However, since the cleaning roller 12 rotates in the counterclockwise direction (the direction opposite to the direction of the arrow) during the latter redeposition step, the cleaning roller 12 shown in FIG. 20 and the leveling blade 18 shown by the solid line are shown.
The toner easily accumulates and accumulates in the damming portion 24 on the opposite side of the photoconductor 1 between the and. In FIG. 20, reference numeral T ₂ ′ indicates the collected toner layer on the cleaning roller 12, but when the toner is reattached, the toner of the collected toner layer easily accumulates in the dam portion 24. When a large amount of toner remains in the damming portion 24 at the end of re-adhesion of toner, the residual toner rides on the cleaning roller 12 which rotates clockwise in the figure, and the cleaning roller 12 rotates on the roller at the time of the next toner recovery. It is conveyed and comes into contact with the surface of the photoconductor 1. The large amount of toner remaining on the cleaning roller 12 weakens the static electricity received from the cleaning roller 12, which easily separates from the cleaning roller 12. Therefore, when the toner contacts the surface of the photoconductor 1, the toner is exposed to light. It adheres to the surface of the body 1, which causes the background stain on the photoreceptor 1.

Therefore, in each of the above-mentioned configurations, when the cleaning member is a cleaning member which rotates in the opposite direction at the time of toner recovery and at the time of toner re-adhesion, at the time of toner re-adhesion, for example, a leveling blade 18 is provided. A drive means for driving the leveling member is provided so that the leveling member is displaced from the leveling operation position to a position shown by an imaginary line in FIG. It is advantageous. For example, the leveling blade 18 is separated from the photoconductor 1 at the start of the toner reattachment operation. In this way, when re-adhering toner, the leveling blade 18 is attached to the cleaning roller 1
If it is separated from 2, the portion 24 where the toner is dammed cannot be formed, so that the above-mentioned toner accumulation can be prevented. As a result, the background stain on the image can be prevented.

Here, the "leveling operation position" means
The leveling blade 18 or another leveling member is pressed against the surface of the cleaning member composed of, for example, the cleaning roller 12, or is opposed to the surface of the cleaning member with a minute gap to smooth the toner collected on the cleaning member. It is a possible position. As the leveling member driving means for displacing the leveling member between the leveling operation position and the separated position, for example, a well-known driving means such as a solenoid, a motor, or a rotating cam (not shown) may be appropriately used. it can.

Here, in each of the above-described configurations, when the cleaning member is a cleaning member that rotates in opposite directions at the time of toner recovery and toner re-adhesion,
As shown in FIG. 13, downstream of the rotation direction of the cleaning member at the time of toner recovery (clockwise in FIG. 13) from the contact portion between the cleaning member composed of the cleaning roller 12 and the image bearing member composed of the photoconductor 1, for example. To the side α = 90
If the toner leveling portion 18a of the leveling member is installed within the range of °, the following effects can be obtained.

If the leveling blade 18 is provided outside the above-mentioned range of 90 °, for example, at the position shown in FIG. 19, the cleaning roller 12 rotates clockwise in FIG. In a state where the residual toner is collected and then the collecting operation is finished, among the collected toner on the peripheral surface of the cleaning roller 12, the collected toner in the H region that does not pass through the smoothing blade 18 is collected by the blade 18. It will not be done. Therefore, at the next toner reattachment, the cleaning roller 12
However, if the toner is controlled to rotate in the counterclockwise direction in FIG. 19, which is the opposite of that at the time of toner collection, the toner in the H region that has not been smoothed will re-adhere to the photoconductor 1 as it is. At this time, if the toner in the H region is partially quantitatively large in the axial direction of the cleaning roller 12, it becomes difficult to reattach all the quantitatively large amount of toner to the photoconductor 1. The effect obtained by providing the leveling blade 18 cannot be sufficiently obtained.

Therefore, as shown in FIG. 13, the part where the leveling blade 18 actually levels the toner on the cleaning roller 12, that is, the leveling part 18a is set to 9 as described above.
By providing it within the range of 0 °, it is possible to reduce the amount of toner that is not smoothed at the end of toner recovery. The leveling part 18a of the leveling blade 18,
This effect can be enhanced as the contact portion between the photoconductor 1 and the cleaning roller 12 is brought closer to the contact portion. However, according to the experiment, cleaning at the time of toner recovery from the contact portion between the cleaning member and the image carrier is performed. If the leveling member is provided within the range of 90 ° to the downstream side in the rotational direction of the member, the collected toner on the cleaning member can be leveled as a whole, and a large amount of toner is partially left on the cleaning roller 12. It has been confirmed that this can be prevented and the occurrence of background stain on the photoconductor 1 can be prevented.

By the way, when the cleaning roller is rotated in the opposite direction at the time of toner collection and the time of re-adhesion of the toner, and the leveling member is fixed immovably, as described above with reference to FIG. During the re-adhesion operation, there is a problem that a large amount of toner accumulates in the damming portion 24 on the side opposite to the photoconductor 1. Therefore, in the example shown in FIG. 20, the leveling blade 18 is set to the cleaning roller 1 during the toner reattachment operation.
Although it is configured to be separated from the No. 2, according to this configuration, a leveling member driving unit is required, which increases the cost of the image forming apparatus.

Therefore, for example, the cleaning roller 12
By controlling the rotation of the cleaning member including the cleaning member so that the cleaning member rotates in the same direction when the toner is collected and when the toner is redeposited, all the above problems can be solved. As described above, the cleaning member may be rotated in the same direction or in the opposite directions during the toner recovery and the toner re-adhesion.
The former one of them is adopted. For example, when the cleaning roller 12 shown in FIG. 19 is configured to rotate in the direction indicated by the solid line arrow when collecting toner, the cleaning roller is rotated in the same solid line direction even when toner is reattached. In this way, the portion 24 does not block the toner, the toner does not accumulate there, and it is possible to prevent the occurrence of background stain on the image due to the toner accumulation. In addition, it is not necessary to provide a leveling member driving means for driving the leveling member toward and away from the cleaning member.

Further, according to the above-mentioned structure, the leveling portion 18a of the leveling member including the leveling blade 18 is
As shown in FIG. 19, even if the toner is not at the position of α = 90 ° (FIG. 13), the toner collected by the cleaning roller 12 is always leveled by the leveling member, and the collected toner is transferred to the photoconductor 1. It is possible to prevent a decrease in redeposition efficiency. As described above, according to this configuration, it is possible to increase the degree of freedom regarding the location of the leveling member. Also, this configuration can be applied to all the above-described configurations other than the configuration in which the cleaning member is rotated in the opposite direction at the time of collecting the toner and the time of reattaching the toner.

In the series of embodiments described above, the flattening blade 18 extending in parallel with the cleaning roller 12 is used as the leveling member, and the leveling member is shown in FIG. Normalizing roller 28
May be used. The leveling roller 28 also faces the cleaning roller 12 and extends substantially parallel to the cleaning roller 12, and is rotatably supported by, for example, the front and rear side walls 17a of the cleaning case 17 shown in FIG.
The roller 28 is rotatably driven in an appropriate direction by a control driving means (not shown), or is rotated by the rotation of the cleaning roller 12. The leveling roller 28 can also level the toner collected on the cleaning roller 12 effectively in the axial direction of the cleaning roller 12, and can achieve the same effect as the leveling blade 18.

Even when the leveling roller 28 is used as the leveling member, it is possible to employ all of the above-mentioned configurations applied when the leveling blade 18 is used. As a result, the above-described operational effects provided by the respective configurations can be provided substantially as they are. The leveling portion 28a of the leveling roller 28 shown in FIG. 21 is also within the range of α = 90 ° from the contact portion between the cleaning roller 12 and the photosensitive member 1 to the downstream side in the rotation direction of the cleaning roller 12 when collecting toner. It is provided.

The leveling roller 28 is replaced with the cleaning roller 1
The collected toner on the cleaning roller 12 can be smoothed by rotating it in the counter direction or in the forward direction with respect to the rotation direction of 2, but as shown in FIG.
In both cases of collecting the transfer residual toner on the photoconductor 1 to the cleaning roller 12 and reattaching the collected toner to the photoconductor 1, the flattening roller 28 and the cleaning member face each other. When the rotation of the leveling roller 28 is controlled so that the leveling roller and the cleaning member move in the same direction, the wedge-shaped portions 25A and 25B defined by the leveling roller 28 and the cleaning roller 12 are formed.
It is possible to prevent a large amount of toner from accumulating. The rotation direction of the leveling roller 28 is controlled so that the leveling roller 28 rotates in the forward direction with respect to the rotation direction of the cleaning roller 12.

As a result, when the transfer residual toner on the photoconductor 1 is collected, it is possible to prevent a problem that a large amount of toner accumulated on the cleaning roller 12 accidentally adheres to the photoconductor 1. At this time, the leveling roller 28 may be driven by the rotation of the cleaning roller 12 to rotate in the forward direction with respect to the rotation direction of the cleaning roller 12, or the leveling roller 28 may move in the forward direction with respect to the cleaning roller 12. The leveling effect may be further enhanced by driving and positively rotating.

If the above configuration is adopted, the leveling roller 28
It is possible to prevent a large amount of toner from accumulating on the wedge-shaped portions 25A and 25B without adopting a configuration in which the toner is moved toward or away from the cleaning roller 12. Further, if this configuration is adopted together with the configuration in which the leveling roller 28 is opposed to the cleaning roller 12 with a minute gap therebetween, the toner easily passes through the gap, so that a large amount of toner is present in the wedge-shaped portions 25A and 25B. It is possible to more surely prevent problems accumulated in the.

As described above, the form of the leveling member can be appropriately set other than the blade or the roller.

The present invention is an image forming apparatus using not only a roller-shaped cleaning member but also an endless belt-shaped one as a cleaning member, or an image formation using an endless belt-shaped one as an image carrier. It can also be applied to devices. Further, the present invention can be applied to an image forming apparatus 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 the toner image is transferred to a transfer material. Further, according to the present invention, after the image bearing member is charged by the charging device, an electrostatic latent image is formed by a portion which is not irradiated with light at the time of image exposure on the surface thereof, and the electrostatic latent image is charged to a polarity opposite to the polarity of the latent image potential. It is also applicable to a so-called positive / positive developing type image forming apparatus in which toner is attached to the electrostatic latent image for development.

[0101]

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 an image forming apparatus that redeposits the toner and then electrostatically collects the redeposited toner to the developing device, the amount of collected toner on the cleaning member can be made uniform in the axial direction. It is possible to prevent a partial decrease in the re-adhesion efficiency of the toner and a partial decrease in the toner recovery efficiency. Further, since the charge having the same polarity as the toner charging polarity at the time of development can be injected into the abnormal polarity toner collected in the cleaning member, the background stain on the image caused when the abnormal polarity toner is reattached to the image carrier. It is possible to prevent the generation and further prevent the discharge between the cleaning member and the leveling member.

According to the image forming apparatus of the second aspect,
Since the toner collected by the cleaning member is directly subjected to the leveling force by the leveling member, the leveling effect can be enhanced.

According to the image forming apparatus of claim 3,
Premature wear of the contact surfaces of the cleaning member and the leveling member can be prevented, and the service life of both can be extended. Also,
The toner leveling function and cleaning function can be stably performed over a long period of time.

According to the image forming apparatus of claim 4,
It is possible to prevent the toner from scattering from both ends of the cleaning member and the leveling member, and prevent the periphery of the cleaning member from being contaminated with the toner.

[0105]

[0106]

According to the image forming apparatus of the fifth aspect,
Since it is possible to prevent the toner from accumulating and accumulating in the portion between the cleaning member and the leveling member when the collected toner is reattached, it is possible to prevent the toner from adhering to the image carrier during the next toner recovery. It is possible to prevent the occurrence of background stain on the image.

According to the image forming apparatus of claim 6,
Since it is possible to reduce the amount of toner that does not pass through the leveling member during toner collection, the effect of the leveling member can be enhanced.

According to the image forming apparatus of claim 7,
When reattaching the collected toner, it is possible to prevent toner from accumulating in the portion between the cleaning member and the leveling member.
When the toner is collected next time, the accumulated toner can be prevented from adhering to the image carrier, and the occurrence of background stain on the image can be prevented. Further, the collected toner on the cleaning member can be leveled by the leveling member without fail, and the leveling effect can be enhanced.

According to the image forming apparatus of claim 8,
Since the leveling blade has a simple structure and is relatively inexpensive, it is possible to avoid a complicated structure of the image forming apparatus and an increase in its cost.

According to the image forming apparatus of claim 9,
With a simple configuration, a predetermined leveling effect can be obtained regardless of the rotation direction of the cleaning member.

According to the image forming apparatus of the tenth aspect, when the toner collected on the cleaning member is smoothed, or when the collected toner is passed between the cleaning member and the smoothing member, the cleaning member It is possible to prevent the toner from accumulating in the wedge-shaped portion between the leveling roller.

[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 an explanatory diagram similar to FIG. 3, illustrating a midway state during toner reattachment when the cleaning roller rotates in the same direction as toner recovery during toner reattachment.

FIG. 13 is an explanatory diagram illustrating a state in which the toner collected by the cleaning roller is leveled by a leveling blade.

FIG. 14 is an explanatory diagram illustrating a manner in which quantitatively non-uniform toner collected by a cleaning roller is leveled by a leveling blade.

FIG. 15 is a configuration diagram around the cleaning roller when the leveling blade is brought into pressure contact with the cleaning roller.

FIG. 16 is a configuration diagram around the cleaning roller when the leveling blade is opposed to the cleaning roller with a gap.

FIG. 17 is a cross-sectional view of a part of the configuration around the cleaning roller when the gap between the cleaning roller and the leveling roller is set by a gap setting member.

FIG. 18 is a cross-sectional view of a part of the configuration around the cleaning roller when a side seal is provided at the ends of the cleaning roller and the leveling blade.

FIG. 19 is an explanatory diagram showing an example in which a leveling blade is provided at a position away from a contact portion between a photoconductor and a cleaning roller.

FIG. 20 is an explanatory diagram showing a configuration for driving the leveling blade toward and away from the cleaning roller.

FIG. 21 is an explanatory diagram showing how the collected toner is leveled when a leveling roller is used as a leveling member.

FIG. 22 is an explanatory diagram showing an example in which the leveling roller is rotated so as to move in the same direction at the facing portion with respect to the rotation direction of the cleaning roller.

[Explanation of symbols]

4 developing device 18 leveling blade 18a leveling section 23 side seal 28 leveling roller 28a leveling section G Gap T ₁ toner T ₂ toner T ₃ toner

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masako Yoshii 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) Reference JP-A-54-61538 (JP, A) JP-A-SHO 62-27783 (JP, A) JP-A-56-138768 (JP, A) JP-A-62-156686 (JP, A) JP-A 61-100779 (JP, A) JP-A-7-234619 (JP, A) A) Japanese Patent Publication Sho 61-30274 (JP, B1) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 21/00

Claims (10)

(57) [Claims] 1. An image carrier that is driven to rotate, a latent image forming unit that forms an electrostatic latent image on the carrier, and a developing device that visualizes the electrostatic latent image as a toner image. A transfer device that transfers the toner image on the image carrier to a recording medium, and electrostatically and temporarily collects the transfer residual toner while rotating, and then collects the collected toner on the image carrier. A cleaning member that electrostatically redeposits on the surface portion that does not affect the formation of the latent image, and when the transfer residual toner is collected, the cleaning member has a polarity opposite to the charging polarity of the toner during development. When the collected toner is reattached to the surface of the image carrier, a voltage having the same polarity as the charging polarity of the toner at the time of development is applied to the cleaning member to reattach the toner to the surface of the image carrier. Toner in the developing device electrostatically In the image forming apparatus for collecting, a conductive leveling member that smoothes the toner collected by the cleaning member in the axial direction of the cleaning member is placed in opposition to the surface of the cleaning member, and the transfer residual toner is collected by the leveling member. An image forming apparatus characterized in that a voltage applying means for applying a voltage having the same polarity as the toner charging polarity at the time of development is provided. 2. The image forming apparatus according to claim 1, wherein the leveling member is opposed to the surface of the cleaning member so as to be in pressure contact therewith. 3. The image forming apparatus according to claim 1, wherein the leveling member is opposed to the surface of the cleaning member with a gap. 4. The image forming apparatus according to claim 1, wherein side seals for preventing toner scattering are provided on both axial ends of the cleaning member and the leveling member. 5. When the cleaning member is a cleaning member that rotates in opposite directions during toner recovery and toner re-adhesion, the leveling member during toner re-adhesion
5. The image forming apparatus according to claim 1, further comprising a leveling member driving unit that drives the leveling member such that the leveling member is displaced to a position farther from the cleaning member than the leveling operation position. 6. When the cleaning member is a cleaning member that rotates in opposite directions during toner recovery and toner re-adhesion, the toner leveling portion of the leveling member contacts the cleaning member and the image carrier. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided within a range of 90 ° from the contact portion to the downstream side in the rotation direction of the cleaning member when collecting the toner. 7. The image forming apparatus according to claim 1, wherein rotation of the cleaning member is controlled so that the cleaning member rotates in the same direction when the toner is collected and when the toner is reattached. 8. The image forming apparatus according to claim 1, wherein the leveling member is a leveling blade. 9. The image forming apparatus according to claim 1, wherein the leveling member is a leveling roller. 10. The leveling roller and the cleaning member are arranged so that the leveling roller and the cleaning member move in the same direction at the facing portion of the leveling roller and the cleaning member in both cases of collecting the toner and re-adhering the toner. The image forming apparatus according to claim 9, wherein the rotation of the roller is controlled.