JPH10254323A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the deterioration of image quality caused by the wear of the surface of an image carrier and soiling in a fish shape and to obtain a high-quality image by switching and controlling either the linear velocity of a brush roller or the linear velocity of the surface of the image carrier so that the value of a difference between them may be changed while the image carrier is rotated. SOLUTION: Until a photoreceptor 1 stops rotation from starting the rotation, the rotating velocity of at least either the brush roller 10 or the photoreceptor 1 is switched at least once and controlled so that the value of the difference between the linear velocity V1 of the brush roller 10 and the linear velocity V2 of the surface of the photoreceptor at a brush part 14a coming in contact with the surface of the photoreceptor may be changed. Namely, operation for performing the rotation by setting the difference of the linear velocity V1 -V2 =V3 small and operation for performing the rotation by setting the difference of the linear velocity V3 large are properly and alternately changed to be performed. Thus, the soiling in the fish shape and irregularities in the image caused by the wear of the surface of the photoreceptor are avoided over a long term.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image carrier having a toner image formed on the surface thereof while being rotated, a transfer device for transferring the toner image formed on the surface of the image carrier to a transfer material, and a toner. A cleaning device for removing transfer residual toner adhering to the surface of the image carrier after the image transfer and cleaning the surface of the image carrier; and the cleaning device is provided around a core shaft driven to rotate and around the core shaft. The present invention relates to an image forming apparatus including a brush roller having a brush, the brush roller rotating while the brush contacts a surface of an image carrier after transfer of a toner image.

[0002]

2. Description of the Related Art In an image forming apparatus of the above-mentioned type configured as a copying machine, a printer, a facsimile, or a multifunction machine having at least two of these functions, a brush of a rotating brush roller is rotated during an image forming operation. Since the surface of the image carrier is in contact with the surface of the image carrier, there is a possibility that the surface of the image carrier is worn relatively early by an external force received from the brush.
When such wear occurs, the image transferred to the transfer material is disturbed, and the image quality deteriorates. In order to prevent such a problem, the difference between the linear velocity of the surface of the image carrier and the linear velocity of the brush of the brush roller contacting the surface is reduced so that a large external force does not act on the surface of the image carrier. It is desirable.

On the other hand, an additive is externally added to a toner for forming a toner image on the surface of an image carrier, and when the additive is released from the toner, the additive adheres to the surface of the image carrier. Then, starting from the attached additive, toner accumulates, and the accumulated toner is blocked by the additive, and the toner gradually adheres to the surface of the image carrier.
When such toner sticking occurs, dirt consisting of a naked image appears on the background of the toner image, and the image quality is degraded.

In order to prevent the generation of such stains, the aforementioned speed difference between the brush of the brush roller and the image carrier is set to be large, a large external force is applied to the surface of the image carrier, and the surface is fixed to the surface. The scraped toner may be scraped off.

However, if the difference in linear velocity between the brush of the brush roller and the surface of the image carrier is set to be large, this time,
As described above, the wear of the surface of the image bearing member is promoted, and the image quality is thereby deteriorated. As described above, if the speed difference between the brush and the surface of the image bearing member is reduced, contaminant dirt is generated. Conversely, if the speed difference is increased, the image quality deteriorates due to wear of the surface of the image bearing member.

Therefore, if the speed difference is not large,
The rotation speed of the image carrier and the brush roller is set to an intermediate size that is not small, and any defects such as eye-like dirt and image quality deterioration due to wear of the image carrier surface are minimized. Although it is conceivable to adopt a configuration in which it is fixed, it has been found from studies by the present inventor that adopting such a configuration cannot effectively prevent any of the disadvantages.

[0007]

SUMMARY OF THE INVENTION The present invention has been made based on the above-described novel recognition, and an object of the present invention is to effectively reduce the occurrence of image quality deterioration due to wear of the image carrier surface. An object of the present invention is to provide an image forming apparatus capable of obtaining a high-quality image by suppressing the occurrence of scum-like stains effectively.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an image forming apparatus of the type described at the beginning, wherein an image bearing member is provided between the start of rotation of the image carrier and the stop thereof. The rotational speed of at least one of the brush roller and the image carrier is switched at least once so that the value of the difference between the linear speed of the brush roller and the linear speed of the image carrier surface at the brush portion in contact with the body surface changes. An image forming apparatus provided with a control unit for controlling is proposed (claim 1).

In this case, in the image forming apparatus according to the first aspect of the present invention, the timing of switching the rotation speed is determined before the transfer of the toner image on the surface of the image carrier to the transfer material and the time when the toner image is transferred to the transfer material. Advantageously, it is at least one time after the transfer is completed (claim 2).

Further, in the image forming apparatus according to claim 1 or 2, when the toner image on the surface of the image carrier is transferred to the transfer material, the surface of the image carrier and the brush of the brush roller are in contact with each other. The rotation direction of the image carrier and the brush roller is set so that the two move in the same direction, and after the transfer of the toner image onto the transfer material, the image carrier is moved in the opposite direction to the above direction. By rotating the brush roller at least once in the direction and rotating the brush roller in the opposite direction during the reverse rotation, while increasing the rotation speed of the brush roller more than the rotation speed of the brush roller when transferring the toner image to the transfer material. It is advantageous to carry out the switching of the rotation speed (claim 3).

Further, in the image forming apparatus according to any one of claims 1 to 3, the absolute value of the difference between the linear velocities when the brush roller is rotated at the highest speed with respect to the image carrier is determined. It is advantageous to set the value to 200 mm / sec or more (claim 4).

In the image forming apparatus according to any one of claims 1 to 3, the absolute value of the difference between the linear velocities when the brush roller is rotated at the highest speed with respect to the image carrier is determined. , 200 mm / sec or more and 600 mm / sec or less (claim 5).

Further, in the image forming apparatus according to any one of claims 1 to 5, the absolute value of the difference between the linear velocities when the brush roller is rotated at the lowest speed with respect to the image carrier is determined. , 0 mm / sec or more and 60 mm / sec or less (claim 6).

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings, and the above-mentioned conventional disadvantages will be more specifically clarified with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of an image forming apparatus. In the image forming apparatus shown here, a drum-shaped photosensitive member 1 as an example of an image carrier is rotatably supported around a central axis thereof on a frame of an image forming apparatus main body (not shown). When a print button (not shown) is pressed, the photoreceptor 1 is driven to rotate clockwise as indicated by the symbol A in FIG.

At this time, the surface of the photoreceptor 1 is uniformly charged to a predetermined polarity by the charging device 2, and the charged surface is irradiated with a light image L from an original (not shown).
By exposing the photoreceptor surface in this way, an electrostatic latent image corresponding to the document image is formed here. This electrostatic latent image is visualized as a toner image when it passes through the developing device 3. A toner image is formed on the surface of the photoconductor 1 that is driven to rotate.

On the other hand, a transfer paper 4 as an example of a transfer material is fed from a paper feed unit (not shown), and the transfer paper 4 is fed in the direction of arrow C at a timing matching with the toner image on the photoconductor 1. At this time, the toner image formed on the surface of the photoconductor is transferred onto the surface of the transfer paper 4 by the operation of the transfer device 6 in the transfer unit 5. This transfer paper 4 continues to be indicated by arrow C
And is separated from the photoreceptor 1 to a fixing device (not shown). Here, the toner image transferred onto the transfer paper 4 is fixed on the transfer paper 4. Thus, the transfer paper 4 is discharged out of the apparatus as copy paper.

On the other hand, the surface of the photoreceptor after the transfer of the toner image
The untransferred toner T that has not been transferred to the transfer paper 4 is adhered. The untransferred toner T is removed by the cleaning device 7 and the surface of the photoconductor is cleaned. The surface of the photoreceptor after the cleaning is initialized by being subjected to a charge removing operation by the charge removing device 17, and the above-described operation is continuously performed, so that the toner image is transferred onto the next transfer paper.

As described above, the illustrated image forming apparatus includes:
Photoreceptor 1 on which a toner image is formed on the surface while being driven to rotate
And a transfer device 6 for transferring the toner image formed on the surface of the image carrier to a transfer material comprising transfer paper 4
And a cleaning device 7 for removing the transfer residual toner T adhered to the surface of the image carrier after transferring the toner image and cleaning the surface of the image carrier.

The cleaning device 7 includes a cleaning case 8 and a cleaning blade 9 as shown in FIG.
The cleaning blade 9 is made of an elastic material such as rubber. The base end of the cleaning blade 9 is fixedly supported by the cleaning case 8 via the mounting bracket 12, and the free end thereof. Is pressed against the surface of the photoconductor 1.

The brush roller 10 has a core shaft 13 housed in the cleaning case 8 and formed of a rigid body extending in parallel with the photosensitive member 1, and a brush 14 provided around the core shaft 13. doing. The core shaft 13 is rotatably supported on the front and rear side walls of the cleaning case 8,
The brush roller 10 is rotationally driven by a motor 15 schematically shown in FIG. 2, whereby the entire brush roller 10 is rotationally driven around its central axis. The rotation direction of the brush roller 10 may be clockwise in FIG. 2 or counterclockwise, but in the illustrated example, the arrow B in FIG.
It is assumed that it is driven to rotate counterclockwise as shown by.
In this way, the brush roller 10 has its brush 14
Rotates while contacting the photoreceptor surface after the transfer of the toner image. The cleaning blade 9 and the brush roller 10 extend in the direction perpendicular to the plane of the drawing over the entire image area in the axial direction of the photoconductor 1, that is, the area where the transfer residual toner T adheres.

When the transfer residual toner T is conveyed to the cleaning device 7, the transfer residual toner T is stopped by the leading edge of the cleaning blade 9 and is scraped off from the surface of the photosensitive member 1. This prevents toner from adhering to the surface of the photoconductor downstream of the cleaning device 7. The surface of the photoconductor 1 is cleaned. The transfer residual toner scraped off by the cleaning blade 9 is
The brush roller 10 falls down, is received by the brush 14 of the brush roller 10, and is conveyed away from the photoreceptor surface by the rotation of the brush roller 10. At this time, the tip of the scraping member consisting of the flicker bar 16 whose base end is fixed to the inner surface of the upper wall of the cleaning case 8 is in contact with the brush 14, is received by the brush 14, and is carried by the rotation of the brush roller 10. The remaining transfer toner is knocked down by the flicker bar 16 and the toner discharge member 11
Released toward

The toner discharging member 11 is composed of, for example, a screw or a coil, and is driven to rotate in the direction of arrow D. As a result, the transfer residual toner discharged to the toner discharge member 11 is conveyed to the outside of the cleaning case 8, and
It is sent to a collection tank (not shown) and is stored here.

The rotating brush 14 of the brush roller 10 also contacts the surface of the photoreceptor after the transfer of the toner image to scrape off the transfer residual toner.

As described above, the illustrated cleaning device 7 of the image forming apparatus includes the brush roller 10 having the core shaft 13 that is driven to rotate and the brush 14 provided around the shaft 13. Is the brush 14
Rotates while contacting the surface of the image carrier after transfer of the toner image.

The configuration itself of the image forming apparatus described above is as follows.
There is no difference from the conventional image forming apparatus. At this time, V ₁ the linear velocity of the brush roller in the brush portion 14a which is in contact with the photoreceptor surface, V ₂ the linear velocity of the surface of the photosensitive member 1, the difference between the both lines speed (V ₁ -V ₂₎ When V _3, if the value of the difference V ₃ of the line velocity is too large, as explained earlier, an external force photosensitive member surface is subjected by the brush 14 is increased, the wear of the photosensitive layer of the photosensitive member surface Is promoted.
In particular, if the abrasion becomes non-uniform in the axial direction of the photoreceptor 1, the charge amount on the photoreceptor in the axial direction becomes non-uniform, and the toner image transferred to the transfer paper is disturbed, and the image quality is reduced. to degrade.

As described above, an additive is externally added to the toner for forming the toner image, and the transfer paper 4 also contains the additive. When such additives are released from the toner or the transfer paper over time, they adhere to the surface of the photoconductor 1. Then, since this additive is a fine particle, it is difficult to remove the additive from the photoreceptor surface by the cleaning blade 9. FIG. 3 is an explanatory view schematically showing the state at this time, and the additive attached to the surface of the photoreceptor 1 is indicated by a symbol P. When such fine particles of the additive P adhere to the surface of the photoreceptor, the toner T is accumulated starting from the additive P, as schematically shown in FIG. When the toner T is blocked by the additive, it is difficult to remove the toner by the cleaning blade 9. Therefore, if this is left unattended, large toner sticks to the surface of the photoconductor due to the gradually accumulated toner. Then, for example, in an image forming apparatus that determines a background portion by light irradiation, light does not transmit to the photosensitive layer of the photoreceptor 1 in a portion where the toner is fixed, and thus, the transfer paper 4 As shown in FIG. 7, a dirt Q composed of an eye-like image occurs. This stain appears on the transfer paper 4 at a pitch Z corresponding to the circumference of the photoconductor 1.

[0028] To prevent the occurrence of problems described above, to set a large difference V ₃ of the aforementioned linear velocity, may have a significant force by the brush 14 to the surface of the photosensitive member. This makes it possible to scrape off the toner sticking to the photoreceptor surface,
It is possible to prevent the occurrence of the dirt Q in the shape of a star. However, in this manner to increase the difference V ₃ of the linear velocity, as described above,
Abrasion of the photoreceptor surface is promoted, which causes image disturbance.

In order to clarify the above-mentioned fact, an experimental example conducted by the present inventors using the apparatus shown in FIGS. 1 and 2 will be introduced.

In this experimental example, a photosensitive drum 1 having a surface coated with a polycarbonate photosensitive layer on the surface of a conductor drum was used, and the linear velocity V _{2 of the} surface was 300 mm /.
Seconds. As the brush 14 of the brush roller 10, an acrylic brush is used, the thickness of the bristles is 6 denier / filament, and the bristles are woven into a base cloth in a loop shape, and the density is 500 denier / square inch.
And the height of the hair was 4 mm. The brush roller 10 was formed by spirally winding and fixing the base cloth around a cylindrical core shaft 13 made of stainless steel. The brush 14 of the brush roller 10 is pressed against the surface of the photoreceptor with a bite amount of ₁ mm so that the linear velocity V1 of the brush portion 14a in contact with the surface of the photoreceptor is 360 mm / sec.
Was rotated in the direction of arrow B. The transfer paper 4 was of A4 size, was fed laterally, and the image area ratio of the toner image formed on the transfer paper was 6%.

When the image forming operation is repeatedly performed in the above-described state, the transfer residual toner scraped off from the surface of the photoreceptor by the cleaning blade 9 can be transported to the toner discharge member 11 by the brush roller 10 without fail. In addition, it is possible to prevent the abrasion of the photoreceptor surface from being promoted, and the
Even after obtaining K (K = 1000) copy papers, no image disturbance due to abrasion of the photoreceptor surface was observed. However, when the number of copies reached about 100K, a noticeable stain started to be generated on the transfer paper, and after 300K sheets, a large amount of the stain occurred on the background portion. The experimental results at this time are shown in Table 1 as Comparative Example 1. Comparative Example 1
So the difference V ₃ of the aforementioned linear speed 360 mm / sec -300mm
/ Sec = 60 mm / sec. Incidentally, the linear velocity V ₂ of the linear velocity V ₁ of the brush roller 10 at the contact portion of the brush 14 and the photosensitive member surface and the photosensitive member surface, the direction indicated by the arrow S in FIG. 2 as positive, negative the opposite direction It is determined.

[0032]

[Table 1]

"Image disturbance" in Table 1 indicates image disturbance caused by abrasion of the surface of the photoreceptor, and "medium-like dirt" indicates contamination generated on transfer paper due to toner sticking to the surface of the photoreceptor. I have. In addition, “○” indicates that a high-quality image was obtained without occurrence of image distortion or star-shaped dirt, and “△” indicates that slight image distortion or dirt was recognized. Further, “×” indicates that the occurrence of image disturbance or dirt is remarkable. “△ Δ” and “Δ ×” represent an intermediate state between them.

Next, the linear velocity V ₁ of the brush roller 10 is set to 90
The image forming operation was repeated under the same conditions as in Comparative Example 1 except that the setting was set to 0 mm / sec. The linear velocity difference V at this time
₃ is 900 mm / sec-300 mm / sec = 600 mm / sec. The results are shown in Table 1 as Comparative Example 2. As can be seen from this table, in Comparative Example 2, the number of copies was 300.
At the time of reaching K, no visible dirt was generated. However, after 150K copies, image disturbance due to abrasion of the photoreceptor surface occurred, and after 300K sheets, image irregularity was observed as uneven density in the black portion of the image. Got pretty bad.

In Comparative Example 1 described above, the linear velocity difference V ₃ was 6
When the speed is as small as 0 mm / sec, the image disorder due to the abrasion of the photoreceptor surface is less likely to occur, but it indicates that the eye-like stain is generated earlier.

Similarly, in Comparative Example 2, the difference V _{3 in} linear velocity was 60
When the rate is as large as 0 mm / sec, it is possible to prevent the occurrence of glazed dirt, but this indicates that image disturbance due to abrasion of the photoreceptor surface appears early.

Therefore, the present inventor has proposed that the number of copies be 300.
To reach K, out experiments to alter the way the value of the difference V ₃ in the linear velocity. That is, under the same conditions as in Comparative Example 1, when fifty copy sheets were obtained after the start of the experiment, the photosensitive member 1 was moved for a predetermined time from the time when the rear end of the last transfer sheet 4 left the transfer part 5. during rotation, switching the linear velocity V ₁ of the brush roller 10 to 900 mm / sec. Brush roller 10
Create a linear velocity V ₁ 50 sheets of copy paper is set to 360 mm / sec, the after the last transfer paper 4 leaves the transfer section 5, to be cleaned by the cleaning device 7 to the surface of the photosensitive member 1 only when rotating the photosensitive member 1 is of an increased linear velocity V ₁ of the brush roller 10 to 900 mm / sec. Such switching of the linear velocity V ₁ was performed every 50 sheets of copying operation. As a result, as shown in the example of Table 1, even when the number of copies reached 300K, no image disturbance due to abrasion of the photoreceptor surface and no disturbed appearance occurred.

The results are as follows: the operation of rotating the photosensitive member 1 and the brush roller 10 while setting the difference V _{3 in the} linear velocities small;
Appropriate operations set larger the difference V ₃ of the linear velocity rotating the photosensitive member 1 and the brush roller 10, and is subjected to alternated, and Medaka-like stains occurred over a long period of time, due to wear of the surface of the photoreceptor This indicates that the occurrence of image disturbance can be avoided.

By performing the image forming operation by the difference V ₃ is low state of [0039] linear velocity, it is possible to suppress the abrasion of the photosensitive member surface, yet even attempt fixing the toner to the photoreceptor surface during the next linear velocity execution of the operations to set the difference V ₃ of the larger, have a significant external force from the brush 14 to the photosensitive member surface, adhered, or the toner can be a scraping to be secured, can be prevented the occurrence of Medaka like dirt It is.

The image forming apparatus of this embodiment is in contact with the surface of the image carrier between the start of rotation and the stop of the rotation of the image carrier based on the novel recognition described above. as the value of the difference in linear velocity V ₂ of the linear velocity V ₁ and the surface of the image bearing member of the brush roller 10 in the brush portion 14a is changed at least once switched at least one of the rotational speed of the brush roller 10 and the image carrier Control means 18 for controlling
Is provided.

In the example shown in FIG. 2, the number of rotations of the motor 15 for rotating the brush roller 10 is controlled by the control means 18, and the linear velocity difference V _3, for example, to 60 mm / sec to perform image forming operation, until the photosensitive member 1 which is stopped from the start of the rotation, so that the difference V ₃ in the linear velocity becomes, for example, 900 mm / sec, the control means The motor 18 is controlled by 18 to switch the rotation speed of the brush roller 10. Then, the switching control is performed at least once between the start of rotation of the photoconductor 1 and the stop thereof.

The above-described control can be performed by switching the rotational speed of the photosensitive member 1 on the condition that the predetermined image forming operation is not affected. Of course, it is also possible to change both the linear velocities V ₁ and V ₂ of the brush roller 10 and the photosensitive member 1 to change the value of the difference V ₃ between the linear velocities.

According to the above-described structure, as is apparent from the description relating to the embodiment shown in Table 1, the occurrence of image disturbance due to the premature wear of the photoreceptor surface is also caused by a tangled shape caused by toner adhesion. The generation of dirt can also be prevented. Further, it is possible to prevent the occurrence of a noticeable stain without providing a special member around the photoreceptor 1 for removing deposits on the surface of the photoreceptor, thereby reducing the size of the image forming apparatus and its cost. Reduction can be achieved.

The timing for switching the rotation speed is performed even when the toner image on the photosensitive member 1 is being transferred onto the transfer paper 4, before the transfer operation of the toner image is started, or when the transfer is performed. The linear velocity V ₁ , V ₂ of the brush roller 10 (or the photoreceptor 1) may be switched between before the start of the transfer operation and at least one time after the end of the transfer operation. At this time, control of various elements of the image forming apparatus is executed, so that the linear velocities V ₁ and V ₂ of the brush roller 10 (or the photosensitive member 1) can be switched in synchronization with the control timing. , The control mode can be simplified.

For example, the toner image on the photosensitive member 1 is
When you transfer sets the rotational speed of the brush roller 10 so that the difference V ₃ in the linear velocity becomes smaller (e.g. V ₃ =
60 mm / sec) before the leading end of the transfer paper 4 reaches the transfer section 5.
Alternatively, after the rear end of the transfer paper 4 has passed the transfer
The rotation speed of the brush roller 10 is set so that the difference V ₃ between the linear velocity of the brush roller 10 and the linear velocity of the brush roller 10 becomes large (for example, V ₃ =
600 mm / sec).

As described above, the switching time of the rotation speed is
By controlling the toner image on the surface of the image carrier to be transferred to the transfer material at least one of before and after the transfer of the toner image to the transfer material, the control mode is simplified. The possible benefits are obtained.

By the way, in the example shown in FIGS. 1 and 2,
When the toner image on the photoreceptor surface is being transferred to the transfer paper 4,
At a portion where the surface of the photoconductor and the brush 14 of the brush roller 10 are in contact with each other, the photoconductor 1 and the brush roller 10 are moved in the same direction, that is, toward the positive side.
Rotation direction is set. The photoreceptor 1 rotates in the direction of arrow A, and the brush roller 10 rotates in the direction of arrow B. In such an image forming apparatus, the transfer of the toner image onto the transfer paper 4 is completed, and even after the rear end of the transfer paper 4 has left the transfer unit 5, the photoconductor 1 rotates at a predetermined angle, and is cleaned by the cleaning device 7. All the transfer residual toner T is removed. After the cleaning operation is completed, if the photoconductor 1 is rotated in the opposite direction to the above-mentioned direction, that is, in the direction opposite to the arrow A, for example, the leading edge of the cleaning blade 9 is removed. This has the advantage that foreign matter accumulated in the surface can be removed. At this time,
The photoreceptor 1 is rotated backward by at least one rotation, and at the time of the reverse rotation, the rotation speed of the brush roller 10 is higher than the rotation speed of the brush roller 10 when the toner image is being transferred onto the transfer paper 4, thereby achieving the above-described operation. When executing the switching of the rotational speed, without extremely increasing the rotation speed of the brush roller 10, it is possible to increase the difference V ₃ between both the linear velocity V _1, V _2.

Specifically, the transfer of the toner image from the photosensitive member 1 to the transfer paper 4 is completed, and the photosensitive member 1 and the brush roller 10 are respectively moved by arrows until the transfer residual toner is completely collected by the cleaning device 7. Rotate in A and B directions,
The linear velocities V ₁ and V ₂ were set to 360 mm / sec and 300 mm, respectively.
/ As seconds, the difference V ₃ is such that the 60 mm / sec, setting the rotational speed of both. Then, when the collection of the transfer residual toner T is completed, the rotation direction of the photoconductor 1 is switched to the direction opposite to the arrow A, and the linear velocity on the surface is set to -200 mm, for example.
/ Sec. At the same time, the brush roller 10 while being rotated in the direction of arrow B, the linear speed V ₁ for example 400 mm /
Switch to seconds. Such an operation is performed only while the photoconductor 1 rotates at least one rotation and reverses in the direction opposite to the arrow A.
V _1, the difference V ₃ of V ₂ of both the linear velocity at this time, V ₁ -V ₂ =
400 mm / sec − (− 200 mm / sec) = 600 mm / sec. That is, without the rotational speed of the brush roller 10 to that large of 900 mm / sec as shown in the foregoing embodiments, only switching to small as 400 mm / sec, both the linear velocity V _1, the difference between V ₂ V ₃ Can be made the same as the difference V ₃ in the above-described embodiment. Accordingly, it is not necessary to use a particularly large motor as the motor 15 for rotating and driving the brush roller 10, so that the cost of the image forming apparatus can be reduced and its size can be reduced. In this example, the photosensitive member 1 is reversely rotated, together with the removal of foreign substances remained in the leading edge portion of the cleaning blade, increases the difference V ₃ of the linear velocity V _1, V _2, and fixed to the photoreceptor surface, In addition, since the toner to be fixed can be removed, the total time required for performing these operations can be reduced as compared with the case where these operations are separately performed.

In the above-described example, when the toner image on the surface of the image carrier made of the photoreceptor 1 is being transferred onto the transfer material, the surface of the image carrier and the brush 14 of the brush roller 10 are in contact with each other. The rotation direction of the image carrier and the brush roller 10 is set so that the two move in the same direction, and after the transfer of the toner image onto the transfer material, the image carrier is moved in a direction opposite to the above direction. By rotating the brush roller at least once, and rotating the brush roller in the above-described direction during the reverse rotation, the rotation speed is higher than the rotation speed of the brush roller when the toner image is being transferred onto the transfer material. The switching of the rotation speed is performed.

By the way, each of the embodiments described above is
The mode in which the brush roller 10 is rotated at a high speed and the mode in which the brush roller 10 is rotated at a low speed with respect to the photoreceptor 1 are executed while the photoreceptor 1 is rotating. 1 when the brush roller 10 is rotated at the highest speed with respect to the image carrier composed of
_When the absolute value of the difference between ₁ and V ₂ is set to a value of 200 mm / sec or more, the toner adhered to the photoreceptor 1 can be effectively removed.
It has been clarified that the occurrence of a star-like stain can be reliably prevented. At this time, the difference V between the two linear velocities V ₁ and V ₂ is obtained.
_When the absolute value of the value of ₃ is set to a value of 600 mm / sec or less,
It has been found that the brush 14 can prevent the photoconductor 1 from being damaged, and can prevent the abrasion of the photoconductor surface from being promoted.

After all, the difference V ₃ between the two linear velocities V ₁ and V ₂ when the brush roller is rotated at the highest speed with respect to the image carrier.
By setting the absolute value of the value to a value of 200 mm / sec or more and 600 mm / sec or less, it is possible to suppress the wear of the surface of the photoreceptor 1 and effectively prevent the occurrence of dusty dirt.

The absolute value of the difference V ₃ between the two linear velocities V ₁ and V ₂ when the brush roller 10 is rotated at the lowest speed with respect to the image carrier composed of the photoreceptor 1 is set to 0 mm / sec. It has been confirmed by experiments that when the value is set to 60 mm / sec or less, abrasion of the photoreceptor surface can be suppressed, and occurrence of image disorder due to the abrasion can be effectively prevented.

The example of the image forming apparatus in which the image bearing member on which the toner image is formed is the photosensitive member 1 and the transfer material onto which the toner image is transferred is the transfer paper 4 has been described. The present invention is also applicable to an image forming apparatus in which the upper toner image is temporarily transferred to an intermediate transfer member, and the transferred toner image is further transferred to transfer paper. In this case, the toner image formed on the image carrier composed of the photoreceptor is transferred to a transfer material composed of the intermediate transfer body, or the toner image formed on the surface of the image carrier composed of the intermediate transfer body is transferred on transfer paper. It will be transferred to the material. The present invention is widely applicable to other various types of image forming apparatuses.

The present invention is also applicable to an image forming apparatus having a cleaning device without a cleaning blade.

[0055]

According to the image forming apparatus of the present invention, the image is disturbed due to the abrasion of the surface of the image carrier, and the surface of the transfer material is caused by the toner sticking to the surface of the image carrier. In addition, it is possible to prevent the occurrence of dirt, and to always form a high-quality image.

According to the image forming apparatus of the second aspect,
The switching control of the rotation speed can be simplified.

According to the image forming apparatus of the third aspect,
Even if the rotation speed of the brush roller is not extremely increased, the difference between the linear speeds of the brush roller and the image carrier can be increased, and the motor for driving the brush roller can be reduced in size and the cost can be reduced.

According to the image forming apparatus of the fourth aspect,
It is possible to surely eliminate the problem of the appearance of a sticky stain on the transfer material.

According to the image forming apparatus of the fifth aspect,
It is possible to reliably eliminate the problem of the appearance of a sticky stain on the transfer material, and to suppress the occurrence of abrasion on the surface of the image carrier.

According to the image forming apparatus of the sixth aspect,
Abrasion on the surface of the image carrier can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic partial sectional view showing an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a diagram schematically illustrating that toner adheres to the surface of a photoconductor.

FIG. 4 is a diagram for explaining fleck-like dirt formed on transfer paper.

[Explanation of symbols]

 Reference Signs List 6 Transfer device 7 Cleaning device 10 Brush roller 13 Core shaft 14 Brush 14a Brush portion 18 Control means T Transfer residual toner

Claims (6)

[Claims] An image carrier having a toner image formed on the surface thereof while being driven to rotate, a transfer device for transferring the toner image formed on the surface of the image carrier to a transfer material, and an image carrier having a toner image transferred thereon A cleaning device for cleaning the surface of the image carrier by removing transfer residual toner adhering to the body surface, wherein the cleaning device has a core shaft that is driven to rotate and a brush provided around the shaft. In an image forming apparatus in which the brush rotates while being in contact with the surface of the image carrier after the transfer of the toner image, the brush roller has an image formed between the start of the rotation of the image carrier and the stop of the image carrier. At least one of the rotation speed of at least one of the brush roller and the image carrier is changed so that the value of the difference between the linear speed of the brush roller and the linear speed of the image carrier surface at the brush portion in contact with the surface of the carrier changes. An image forming apparatus, further comprising a control unit for performing a switching control. 2. The method according to claim 1, wherein the switching speed of the rotation speed is at least one of a timing before the transfer of the toner image on the surface of the image carrier to the transfer material and a timing after the transfer of the toner image to the transfer material. Item 2. The image forming apparatus according to Item 1. 3. When transferring the toner image on the surface of the image carrier to the transfer material, at a portion where the surface of the image carrier and the brush of the brush roller contact each other, the two move in the same direction. The rotation direction of the image carrier and the brush roller is set, and after the transfer of the toner image to the transfer material is completed, the image carrier is rotated at least once in a direction opposite to the above direction,
During the reverse rotation, the rotation speed is switched by increasing the rotation speed of the brush roller while rotating the brush roller in the direction above the rotation speed of the brush roller when transferring the toner image onto the transfer material. The image forming apparatus according to claim 1, wherein the image forming apparatus executes the processing. 4. The apparatus according to claim 1, wherein the absolute value of the difference between the linear velocities when the brush roller is rotated at the highest speed with respect to the image carrier is set to a value of 200 mm / sec or more. An image forming apparatus according to claim 1. 5. The method according to claim 1, wherein the absolute value of the difference between the linear velocities when the brush roller is rotated at the highest speed with respect to the image carrier is set to a value not less than 200 mm / sec and not more than 600 mm / sec. An image forming apparatus according to any one of claims 1 to 3. 6. The method according to claim 1, wherein the absolute value of the difference between the linear velocities when the brush roller is rotated at the lowest speed with respect to the image carrier is set to a value of 0 mm / sec or more and 60 mm / sec or less. An image forming apparatus according to any one of claims 1 to 5.