JP3337882B2 - Charging device, process cartridge, and image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device, a process cartridge, and an image forming apparatus for charging a photosensitive member surface by bringing a magnetic brush into contact therewith.

[0002]

2. Description of the Related Art There are roughly two types of charging processes for an electrophotographic image forming apparatus such as a copying machine and a laser beam printer. One is a non-contact charging method using a corona charger or the like, and the other is a contact charging method using a roller or a brush.

[0003] In recent years, as ecology has attracted attention, contact charging systems that are advantageous for reducing ozone and reducing power consumption have been increasingly used. Various members such as brushes, roller-shaped fur brushes, and magnetic brushes have been put to practical use.

[0004] Of these, those using a magnetic brush are known to have good uniform contact with a photoreceptor, which is one of the conditions required for a contact charging member.

FIG. 9 shows an example of a magnetic brush. In the figure, a magnetic brush 105 is formed by attaching magnetic particles to the surface of a rotatable conductive sleeve 103 containing a fixed magnet 102 by the magnetic restraining force of the magnet 102. The carried magnetic particles are brought into contact with the surface of the photoconductor 101. Then, the conductive sleeve 10 is moved with respect to the surface of the photoconductor 101 moving in the direction of arrow B.
By moving this in the direction of arrow A while applying a charging voltage to 3, the surface of the photoconductor 101 is charged to a predetermined voltage via the magnetic particles.

[0006]

However, according to the above-described magnetic brush, when the magnetic brush is separated from the photoreceptor, the magnetic particles having escaped the magnetic restraining force are transferred to the developing unit and the transfer unit as the photoreceptor rotates. This causes problems such as poor development, poor transfer and poor charging due to reduced magnetic particles.

That is, the magnetic brush 105 serving as the contact charging member is cleaned or replaced for the purpose of cleaning or replacement.
1, the photosensitive member 10 is separated from the photosensitive member 10 as shown in FIG.
The accumulation portion of the magnetic particles 104 generated by the movement of the surface in the direction of arrow B and the movement of the surface of the conductive sleeve 103 in the direction of arrow A remains in a state of being attached to the surface of the photoconductor 101. Even when the magnetic brush 105 is brought into contact with the photoreceptor 101 again, the pool of the magnetic particles 104
Not all of the magnetic particles are necessarily pulled back to the magnetic brush 105 side, and magnetic particles remaining on the photoconductor 101 are also generated. The remaining magnetic particles adversely affect image formation after charging in the next and subsequent image formation.

More specifically, image exposure is inhibited by the magnetic particles 104 attached to the photoreceptor 101. Developing failure at the position where the magnetic particles 104 adhere to the photoconductor 101. Deterioration of developability when the magnetic particles 104 are mixed in the developing device. When the magnetic particles 104 are transferred to the transfer material, a fixing failure occurs because the magnetic particles 104 are not fixed in a fixing step after the transfer. Damage to the photoreceptor due to magnetic particles not transferred to the transfer material being caught between the cleaning blade and the photoreceptor at the cleaning position. And so on.

On the other hand, when viewed from the side of the magnetic brush 105, a part of the magnetic particles 104 is robbed by the photoreceptor 101, so that the number of the magnetic particles 104 contributing to charging is reduced. As a result, the new photoconductor 10 having no magnetic particles 104 attached thereto
Even in the case of using No. 1, the magnetic brush 105 having the reduced number of magnetic particles 104 cannot obtain good contact with the new photoconductor 101, and cannot uniformly charge the photoconductor 101.

[0010] The above-mentioned problem also occurs in a magnetic brush having another configuration, for example, a magnetic brush in which magnetic particles are directly adhered to the surface of a rotatable magnet by a magnetic binding force.

Accordingly, the present invention is directed to a charging device which prevents magnetic particles on a conductive sleeve from adhering to the surface of a photoreceptor, and prevents image defects caused by the magnetic particles adhering to the surface of a photoreceptor. , A process cartridge, and an image forming apparatus.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a magnet member provided inside a rotatable conductive sleeve, and the outer surface of the conductive sleeve is provided by the magnet member. Forming a magnetic brush by constraining the magnetic particles, rotating the conductive sleeve in a direction opposite to the rotation of the photoconductor at a contact portion between the magnetic brush and the surface of the photoconductor, and applying a charging voltage to the conductive sleeve. In a charging device that charges the surface of the photoconductor by applying a voltage, a separation mechanism that separates the magnetic brush and the photoconductor during non-image formation, and a photoconductor of the contact portion before the separation operation by the separation mechanism. the magnetic particles of the magnetic particles reservoir portion of the downstream side in the rotational direction so as to peel off from the sensitive optical surface, at least one of said magnet member and the conductive sleeve Comprising magnetic particles separation promoting mechanism for peeling rotated by a predetermined angle, a, the magnetic brush and the photosensitive member
Rotation stop position of the magnet member before the separating operation
The one of the magnetic poles of the magnet member is
Connects the maximum spike length of particles to the center of rotation of the conductive sleeve
It is characterized by being arranged in the vicinity of an elliptical line .

The magnetic particle separation accelerating mechanism can rotate the magnet member in the same direction as the rotation direction of the conductive sleeve during image formation.

The magnet member has a plurality of magnetic poles in the direction of rotation of the conductive sleeve. During the charging operation, one of the plurality of magnetic poles is moved between the center of rotation of the conductive sleeve and the rotation of the photosensitive member. From the line connecting the center to the photoconductor, it is preferable to arrange it within a range of 1 degree to 15 degrees on the upstream side in the photoconductor rotation direction.

The rotation stop position of the magnet member before the separating operation between the magnetic brush and the photoreceptor is determined. One of the magnetic poles of the magnet member determines the maximum spike length of the magnetic particles and the rotation center of the conductive sleeve. It is good to arrange it near the connected line.

The magnetic particle separation accelerating mechanism may also rotate the conductive sleeve in a direction opposite to the rotation direction of the conductive sleeve during image formation.

[0017]

The magnetic particle separation accelerating mechanism can separate and rotate the magnet member in a direction opposite to the rotation direction of the magnet member during image formation.

It is preferable that the separation rotation operation by the magnetic particle separation promotion mechanism is linked to the separation operation by the separation mechanism.

A process cartridge detachably mounted to an image forming apparatus main body, wherein a magnet member is disposed inside a photosensitive member and a rotatable conductive sleeve;
The magnet member restrains the magnetic particles on the outer surface of the conductive sleeve to form a magnetic brush, and rotates the conductive sleeve in a direction opposite to the rotation of the photoconductor at a contact portion between the magnetic brush and the surface of the photoconductor. And a charging device that charges the surface of the photoconductor by applying a charging voltage to the conductive sleeve, and before removing the process cartridge from the image forming apparatus main body, Magnetic particles in the magnetic particle pool at the downstream of the contact part in the rotation direction of the photoconductor
The so separated from the sensitive optical surface, comprising a magnetic particle separation promoting mechanism for peeling rotated by a predetermined angle at least one of said magnet member and the conductive sleeve, before
Of the process cartridge from the image forming apparatus main body.
Rotation stop position of the magnet member before the take-out operation
The one of the magnetic poles of the magnet member is
Connects the maximum spike length of particles to the center of rotation of the conductive sleeve
It is characterized by being arranged in the vicinity of an elliptical line .

The magnetic particle separation accelerating mechanism can separate and rotate the magnet member in the same direction as the rotation direction of the conductive sleeve during image formation.

The magnet member has a plurality of magnetic poles in the direction of rotation of the conductive sleeve. During the charging operation, one of the plurality of magnetic poles is moved between the rotation center of the conductive sleeve and the rotation of the photosensitive member. From the line connecting the center to the photoconductor, it is preferable to arrange it within a range of 1 degree to 15 degrees on the upstream side in the photoconductor rotation direction.

Before the removal of the process cartridge from the main body of the image forming apparatus, the rotation stop position of the magnet member is determined by setting one of the magnetic poles of the magnet member to the maximum spike length of the magnetic particles and the rotation of the conductive sleeve. It is good to arrange in the vicinity of the line connecting the center.

The magnetic particle separation accelerating mechanism can also rotate the conductive sleeve in a direction opposite to the rotation direction of the conductive sleeve during image formation.

[0025]

The magnetic particle separation accelerating mechanism can separate and rotate the magnet member in a direction opposite to the rotation direction of the magnet member during image formation.

[0027] The peeling rotation operation by the magnetic particle peeling promotion mechanism may be interlocked with the removal operation of the process cartridge from the image forming apparatus main body.

Next, the image forming apparatus includes a photosensitive member, the charging device described above, an exposure device for exposing the charged photosensitive member to form an electrostatic latent image, and applying a toner to the electrostatic latent image. The image forming apparatus further includes a developing device that forms a toner image by attaching the toner image, and a transfer device that transfers the toner image onto a transfer material.

Further, another image forming apparatus includes an image forming apparatus main body and the above-described process cartridge.
It is characterized by the following.

[Operation] Based on the above configuration, at least one of the conductive sleeve and the magnet member is separated and rotated by a predetermined angle before the magnetic brush and the photosensitive member are separated from each other, thereby adhering to the photosensitive member at the time of separation. Since the area of the magnetic particles is reduced, the magnetic particles are easily separated from the photoconductor.

When a magnetic brush is formed by attaching magnetic particles directly to the surface of a magnet member, the magnetic particles are magnetically constrained by the magnetic force of the surface of the magnet member. The force of peeling off the attached magnetic particles from the photoreceptor also increases.

Further, by setting the rotation direction at the time of peeling rotation of the conductive sleeve and the magnet member as described above,
The magnetic particle pool generated on the downstream side in the rotation direction of the photoconductor can be separated from the photoconductor, and the magnetic particles attached to the photoconductor can be suppressed.

In addition, if the peeling rotation of the conductive sleeve or the magnet member is linked to the separating operation between the magnetic brush and the photosensitive member or the removing operation of the process cartridge from the image forming apparatus main body, during these operations, Since the magnetic particles are always restrained by the magnet member, it is possible to prevent the magnetic particles from dropping off from the magnetic brush and adhering to the photoreceptor due to the vibration during the operation.

Next, when the rotation of the magnet member is stopped at the time of separation, one of the magnetic poles of the magnet member is located near a line connecting the maximum spike length of the magnetic particles and the center of rotation of the conductive sleeve. Can be restrained, so that the adhesion of the magnetic particles to the photoconductor can be suppressed.

Next, it is assumed that one of the magnetic poles of the magnet member is within a range of 1 to 15 degrees upstream from the line connecting the rotation center of the photoconductor and the rotation center of the conductive sleeve in the rotation direction of the photoconductor. During charging, the magnetic particles come into wide contact with the photoconductor (the width of the charging nip becomes wider), so that the photoconductor surface can be uniformly charged.

[0036]

Embodiments of the present invention will be described below with reference to the drawings. <Embodiment 1> This embodiment is characterized in that when the magnetic brush is separated from the photoreceptor, the conductive sleeve is rotated in advance and then separated.

FIG. 1 is a diagram showing a schematic configuration of a printer using an electrophotographic process as an example of an image forming apparatus according to the present invention.

The image forming apparatus 21 shown in FIG. 1 includes a drum-type electrophotographic photosensitive member (hereinafter, referred to as "photosensitive drum") 1 as an image carrier. The photosensitive drum 1 is an OP having a diameter of 30 mm in which a photosensitive layer on the surface is formed by OPC.
It is a C photosensitive member and is driven to rotate in the direction of arrow H at a process speed (peripheral speed) of 100 mm / sec.

Above the photosensitive drum 1, a magnetic brush 2 as a contact charging member is disposed so as to contact the photosensitive drum 1. The magnetic brush 2 includes a magnet roller (magnet member) 6 fixed by a D cut 5 inside a conductive sleeve 3 rotatable in the direction of arrow G. The magnet roller 6 has a two-pole arrangement, and the N pole of the magnet roller 6 has a photosensitive drum about 5 degrees from a line connecting the center of the magnet roller 6 and the center of the photosensitive drum 1 in order to increase the efficiency of charge injection charging. It is arranged on the upstream side in the rotation direction (direction of arrow H). This is to uniformly charge the surface of the photosensitive drum 1 by increasing the area of a so-called charging nip portion formed by magnetic particles 7 described below in contact with the surface of the photosensitive drum 1 during image formation.

The magnetic particles 7 are adhered to the surface of the conductive sleeve 3 by a magnetic restraining force based on the magnetic force of the magnet roller 6 to form the magnetic brush 2 as a whole. Since the magnetic brush 2 moves in the same direction (the direction of arrow G) with the rotation of the conductive sleeve 3, a pool K of the magnetic particles 7 is generated downstream of the charging nip on the photosensitive drum 1. A -700 V DC bias is applied to the magnetic particles 7 from a charging bias application power source (not shown) via the conductive sleeve 3, and the photosensitive drum 1 is charged by charge injection.
The surface is uniformly charged to approximately -700V.

The charged surface of the photosensitive drum 1 is exposed by LED light emission corresponding to a time-series electric digital pixel signal of target image information output from the LED exposing device 9, whereby the photosensitive drum 1 is exposed. An electrostatic latent image corresponding to the target image information is formed on one surface. This electrostatic latent image is transferred to a reversal developing device 10 using magnetic one-component insulating toner.
The toner is thereby adhered and is developed (developed) as a toner image.

On the other hand, a transfer material (not shown) as a recording material from the paper feed tray 7 is transferred to the transport roller 12 and the photosensitive drum 1 with a predetermined pressing force to transfer medium resistance as a contact transfer means. The toner image is introduced into the pressure contact nip portion with the roller 13 at a predetermined timing, and the toner image is transferred to the surface.

The transfer material to which the toner image has been transferred is separated from the surface of the photosensitive drum 1 and is fixed by a fixing device 15 such as a heat fixing method.
And the toner image is fixed to the paper tray 16 as an image formed product (print, copy).
Is discharged to

The transfer residual toner remaining on the surface of the photosensitive drum 1 after the transfer of the toner image is cleaned by the cleaning device 1.
7 and repeatedly provided for image formation.

Next, an operation of separating the magnetic brush 2 from the photosensitive drum 1 will be described with reference to FIGS.

An upper cover 20 is connected to the image forming apparatus 21 by a hinge 22. Inside the upper cover 20, a gear 23 connected to the conductive sleeve 3 to rotate the conductive sleeve 3 and a motor (not shown)
25, a rack plate (magnetic particle separation promoting mechanism) 26, a pressure spring 27, and the like are arranged. When the rack plate 26 is pushed in the direction of arrow L,
The upper cover 20 is opened in the direction of the arrow M, and the magnetic brush 2 is separated from the photosensitive drum 1. The entire magnetic brush 2 is also supported by the upper cover 20. Therefore, a separating mechanism for separating the photosensitive drum 1 from the magnetic brush 2 is provided by the upper cover 2 that can be freely opened and closed.
0, the magnetic brush 2 and the rack plate 26, etc., which are supported thereby.

Next, the opening of the upper cover 20 and the separation of the magnetic brush 2 will be described.

As shown in FIG.
When the rack plate 26 is pushed in the direction of the arrow L, the hook 26a of the rack plate 26 comes off the positioning pin 29. Substantially in parallel with this, the gear 25 is pushed upward by the inclined portion 26c and the horizontal portion 26d of the rack plate 26, and the rack portion 26b of the rack plate 26 is directly connected to the conductive sleeve 3.
Is rotated in a direction opposite to the arrow G by a predetermined angle.
As a result, the magnetic particles 7 adhered around the conductive sleeve 3
Moves slightly with the rotation of the conductive sleeve 3. Due to the movement of the magnetic particles 7, the accumulation of the magnetic particles 7 formed downstream of the charging nip on the photosensitive drum 1 is reduced.
Is slightly lifted in the direction of arrow I.

The charging nip area where the magnetic particles 7 adhere to the photosensitive drum 1 is reduced, and then the upper cover 20 is moved to the arrow M
The magnetic brush 2 supported by the upper cover 20 is separated from the photosensitive drum 1.

As described above, the operation of forcibly rotating the conductive sleeve 3 is performed in conjunction with the operation of separating the magnetic brush 2 from the photosensitive drum 1. Therefore, even when the user accidentally opens the upper cover 20, the conductive sleeve 3 is rotated, so that the magnetic particles 7 are easily separated from the surface of the photosensitive drum 1, and the magnetic particles 7 are scattered. There is no fear.

In this embodiment, the magnet roller 6,
Although the case where the magnetic brush 2 including the conductive sleeve 3 and the magnetic particles 7 is separated from the photosensitive drum 1 has been described, the present invention is not limited to this. For example, the present invention can be similarly applied to a contact charging member of a type in which magnetic particles are directly attached to the surface of a magnet roller and the surface of the photosensitive drum is charged by rotating the magnet roller itself.

As described above, the magnetic brush 2 is connected to the photosensitive drum 1
Before moving the magnetic brush 2 away from the photosensitive drum 1, the magnetic particles 7, which have conventionally tended to collect on the downstream side of the charging nip, float off the surface of the photosensitive drum 1, and then the magnetic brush 2 is separated from the photosensitive drum 1. Of the magnetic particles 7 can be eliminated.

As a result, when the magnetic brush 2 is brought into contact with the photosensitive drum 1 again to output an image, image exposure inhibition due to the adhesion of the magnetic particles 7 to the photosensitive drum 1, poor development, and fixing, which tend to occur conventionally. Problems such as defects, scratches on the photosensitive drum, etc., and charging defects due to the reduction in magnetic particles did not occur, and high-quality images could be output stably. <Second Embodiment> FIG. 3 shows a second embodiment. In addition,
The same members and the like as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the first embodiment, when the magnetic brush 2 having the magnet roller 6, the conductive sleeve 3, and the magnetic particles 7 is separated from the photosensitive drum 1, first, the conductive sleeve 3 is rotated and then separated. By doing so, the adhesion of the magnetic particles 7 to the photosensitive drum 1 is prevented. On the other hand, in the embodiment, first, the magnetic brush 30 is separated from the photosensitive drum 1 after the magnet roller 42 is rotated.

In this embodiment, the magnet roller 42 having a four-pole arrangement is used, and one pole (N1 pole) is the center of the magnet roller 42 and the center of the photosensitive drum 1 as in the first embodiment. And about 5 degrees from the line connecting to the photosensitive drum 1 in the rotation direction (direction of arrow H) of the photosensitive drum 1.
Note that the image forming process is the same as that of the first embodiment, and thus the description is omitted.

Next, a case where the magnetic brush 30 which is a feature of the present embodiment is separated from the photosensitive drum 1 will be described.

An upper cover 31 is connected to the image forming apparatus 32 by a hinge 33. The upper cover 31 includes a magnetic brush 30, a rotating lever (magnetic particle separation accelerating mechanism) 35, a release lever 36, and a pressure spring 37, and the upper cover 31 is configured to open in the arrow J direction.

The operation of separating the magnetic brush 30 from the photosensitive drum 1 will be described with reference to FIGS.

First, in FIG. 3, when the user pushes the release lever 36 in the direction of arrow E, the release lever 36 rotates about the fulcrum 39, and the latch (not shown) is operated to release the lock. The release lever 36 is located on the positioning pin 40.
And presses down the rotating lever 35, which is pressed upward by the pressing spring 37, in the direction of arrow F. As shown in FIG. 4, by rotating the rotation lever 35 in the direction of arrow F, the D cut 5 slightly rotates in the direction of arrow G (clockwise), and the magnet roller 42 is rotated in the direction of arrow G with the rotation. Rotate to. When the magnet roller 42 slightly rotates in the direction of arrow G, the conductive sleeve 3
The magnetic particles 7 adhering to the periphery of the roller slightly move in the direction opposite to the rotation direction of the magnet roller 42, that is, in the counterclockwise direction. Due to the movement of the magnetic particles 7, the pool of the magnetic particles 7 formed downstream of the charging nip on the photosensitive drum 1 is lifted in the direction of arrow I.

Further, since the magnet roller 42 rotates slightly, and the N2 pole comes to the pool of the magnetic particles 7 lifted from the photosensitive drum 1, the magnetic particles 7 are transferred to the conductive sleeve 3.
Can be attracted to. As a result, the adhesion of the magnetic particles 7 to the photosensitive drum 1 can be further reduced, and the magnetic particles 7 do not fall off the conductive sleeve 3 even when vibration or the like occurs during separation.

The area of the charging nip formed when the magnetic particles 7 are brought into contact with the photosensitive drum 1 is reduced.
The magnetic particles 7 separated from the magnetic pole N
Hold at 2. Next, the upper cover 31 is lifted in the direction of arrow J, and the magnetic brush 30 is separated from the photosensitive drum 1.

The operation of rotating the magnet roller 42 is performed in conjunction with the operation of separating the magnetic brush 30 from the photosensitive drum 1. Therefore, even if the user accidentally opens the upper cover 31, the magnetic particles 7 do not scatter unnecessarily.

As described above, before the magnetic brush 30 is separated from the photosensitive drum 1, the pool of the magnetic particles 7 that has conventionally adhered to the photosensitive drum 1 and has been formed downstream of the charging nip portion is floated from the photosensitive drum 1. By holding the floating magnetic particles 7 with the magnetic poles of the magnet roller 42, when the magnetic brush 30 is separated from the photosensitive drum 1, even if the image forming apparatus 32 vibrates, the magnetic particles 7 can be eliminated.

As a result, an image defect which tends to occur when the image is output by bringing the magnetic brush 30 into contact with the photosensitive drum 1 again, that is, image exposure inhibition and development defect due to the magnetic particles 7 attached to the photosensitive drum 1 In this case, there is no problem such as poor fixing, scratches on the photosensitive drum, and poor charging due to the decrease of the magnetic particles 7 on the conductive sleeve 3, and a high-quality image can be output stably.

As another configuration example, there is a configuration in which a unitized charging device is detachably mounted on a photosensitive drum positioned and arranged with respect to an image forming apparatus together with the unit in the apparatus main body. The present invention is also effective in this intoxicating configuration, and can achieve the same effect. Third Embodiment FIG. 5 shows a third embodiment. In addition,
The description of the same parts as those in the above-described embodiment will be omitted.

In the first and second embodiments, when the magnet roller, the conductive sleeve, and the magnetic brush having the magnetic particles are separated from the photosensitive drum 1, the magnetic particles 7 are prevented from adhering to the photosensitive drum 1. I was In the present embodiment, a case where the magnetic brush is moved away from the magnetic brush by moving the photosensitive drum 1 instead of separating the magnetic brush will be described.

In the present embodiment, a magnet roller 46 having a two-pole arrangement is used. As in the first embodiment, the N pole is about 5 degrees from a line connecting the center of the magnet roller 46 and the center of the photosensitive drum 1. The photosensitive drum 1 is arranged on the upstream side in the rotation direction (direction of arrow H). Note that the image forming process is the same as that of the above-described embodiment, and the description thereof is omitted.

Next, the configuration of the present embodiment will be described.

In FIG. 5, reference numeral 47 denotes a rotating lever for rotating the magnet roller 46.
6 are connected to the D cut 49. The rotation lever 47 is rotatable in the direction of arrow P.

Reference numeral 50 denotes a photosensitive drum unit, and the photosensitive drum 1 can be pulled out by a drawer lever 51 in the front direction in the figure. At this time, the rotation lever 47 is configured so that the photosensitive drum unit 50 cannot be pulled out unless it rotates in the direction of arrow P.

Next, a case where the photosensitive drum 1 is separated from the magnetic brush 52, which is a feature of the present embodiment, will be described with reference to FIGS.

First, in FIG. 5, when the user turns the rotary lever 47 in the direction of the arrow P, the rotary lever 47 rotates around the D cut 49 so that the magnet roller 4 is rotated.
6 rotates in the direction of arrow G (clockwise). With the rotation of the magnet roller 46, the accumulation K of the magnetic particles 7
Moves counterclockwise in the same manner as in the second embodiment, and is held by the S pole of the magnet roller 46.

As a result, the area where the magnetic particles 7 contact the photosensitive drum 1 is reduced.

Next, the photosensitive drum unit holding lever 56
Is rotated 180 degrees in the direction of arrow Q about the fulcrum 56a. By this rotation, the photosensitive drum unit 50 is separated from the magnetic brush 52 while being supported by the guide 57, and moves onto the support plate 39. Then, the photosensitive drum unit 50 is pulled out by the pullout lever 51 in the front direction in the drawing.

As described above, the photosensitive drum 1 is
Before being separated from the photosensitive drum 1, a pool of magnetic particles 7 attached to the photosensitive drum 1 downstream of the charging nip is floated from the photosensitive drum 1, and the magnetic particles 7
, The magnetic particles 7 do not adhere to the photosensitive drum 1 and the photosensitive drum 1 can be separated from the magnetic brush 52.

As a result, when the photosensitive drum 1 is brought into contact with the magnetic brush 52 again to output an image, image exposure inhibition, defective development, defective fixing, and defective photosensitive drum due to the magnetic particles 7 on the photosensitive drum tend to occur. Thus, charging failure due to the reduction of magnetic particles and the like does not occur, and a high-quality image can be output stably. <Fourth Embodiment> FIG. 7 shows a fourth embodiment. The description of the same parts as those in the above-described embodiment will be omitted.

In the first to third embodiments, the case where the photosensitive drum or the magnetic brush is provided in the apparatus main body has been described. On the other hand, in the fourth embodiment,
A case in which a process cartridge in which a magnetic brush, a photosensitive drum, a developing device, and a cleaning device are integrally incorporated in a cartridge container is separated from an image forming apparatus will be described.

In the present embodiment, the same magnet roller as that of the first embodiment is used. Similarly to the first embodiment, the N pole (not shown) connects the center of the magnet roller 6 and the center of the photosensitive drum 1. About 5 degrees from the connected line, the photosensitive drum 1 is arranged on the upstream side in the rotation direction (the direction of the arrow H). Note that the image forming process is the same as that of the above-described embodiment, and thus the description is omitted.

Next, the configuration of the present embodiment will be described.

In FIG. 7, reference numeral 60 denotes a front cover of the image forming apparatus 61, which is connected to the image forming apparatus 61 by a hinge 62.

The process cartridge 66 is constructed by integrally incorporating the magnetic brush 2, the developing device 10, the cleaning device 17, and the photosensitive drum 1 in a cartridge container. Conductive sleeve 3 of magnetic brush 2
Is rotatable in the direction of arrow G. Magnetic particles 7 adhere around the conductive sleeve 3 and uniformly charge the surface of the photosensitive drum 1. The magnet roller 6 is included in the conductive sleeve 3, and the gear 63 is a rack plate (magnetic particle separation promoting mechanism) 6.
5 is engaged with the rack portion 65a. Then, pressure is applied to the rack plate 65 upward by a pressure spring 69.

The operation of the magnetic brush 2 when the process cartridge 66 is separated from the image forming apparatus 61 will be described with reference to the operation explanatory views of FIGS.

First, in FIG. 7, when the user pulls the front cover 60 in the direction of arrow R, the process cartridge 66 can be taken out of the image forming apparatus 61. 8, when the user pulls out the process cartridge 66 in the direction of arrow U according to the insertion guide 67, the rack plate 65 of the process cartridge 66 is lifted upward by the force of the pressure spring 69. By this operation, the rack plate 6
5 rotates the gear 63 and the magnet roller 6 directly connected to the magnet roller 6 in the direction of arrow G (clockwise). As a result, the magnetic particles 7 attached to the periphery of the conductive sleeve 3 move slightly with the rotation of the magnet roller 6. Due to the movement of the magnetic particles 7,
The accumulation K of the magnetic particles 7 formed downstream of the charging nip portion on the photosensitive drum 1 is slightly lifted in the direction of arrow I from the photosensitive drum, and similarly to the above-described embodiment, the magnetic particles 7 are formed by S poles (not shown). Is retained.

The charge nip area where the magnetic particles 7 adhere to the photosensitive drum 1 is reduced, and then the process cartridge 66 is taken out of the image forming apparatus 61.

As described above, before the process cartridge 66 is detached from the image forming apparatus 61, the pool K of the magnetic particles 7 conventionally formed downstream of the charging nip is floated off the photosensitive drum 1, and the magnetic particles 7 are removed. By holding the magnetic poles of the magnet roller 6, even if vibrations or the like occur when the process cartridge 66 is taken out, the scattering of the magnetic particles 7 is prevented, and the magnetic particles 7 are prevented from adhering to the photosensitive drum 1. 66 can be detached from the image forming apparatus 61.

The operation of rotating the magnet roller 6 is as follows.
This is linked to the operation of detaching the process cartridge 66 from the image forming apparatus 61. Therefore, even if the user removes the process cartridge 66 by mistake, the magnetic particles 7 do not scatter.

Further, since the magnetic particles 7 are strongly held by the magnet roller 6, the process cartridge 66
The amount of toner in the developing device is reduced, and operations such as shaking the process cartridge 66 to make the toner in the process cartridge 66 uniform can be performed.

As a result, the process cartridge 6
6, which is likely to occur when an image is output by attaching the image forming apparatus 6 to the image forming apparatus 61, such as problems such as image exposure inhibition, development failure, fixing failure, damage to the photosensitive drum, and magnetic particles adhered to the photosensitive drum. 7 does not occur, and a high-quality image can be stably output.

[0089]

As described above, according to the present invention, when the magnetic brush and the photosensitive member are separated from each other, at least one of the conductive sleeve and the magnet member is separated and rotated by a predetermined angle. Adhesion of magnetic particles to the photoconductor at the time of separation can be prevented, magnetic particles can be prevented from decreasing, and the photoconductor surface can be uniformly charged. Further, it is possible to prevent defects in each of the processes of exposure, development, transfer, cleaning, and transfer due to the attachment of the magnetic particles to the photoconductor. When a magnetic brush is formed by constraining magnetic particles on the outer surface of a rotatable magnet member, the magnetic member is separated from the photoreceptor by a simple structure by separating and rotating the magnet member before separation. Can be prevented from adhering. Prior to removing the process cartridge from the image forming apparatus main body, at least one of the conductive sleeve and the magnet member is peeled and rotated by a predetermined angle to prevent the magnetic particles from being scattered at the time of removal and to prevent scatter. When the process cartridge is mounted again in the image forming apparatus and an image is output, defects that tend to occur when the image is output, that is, problems such as image exposure inhibition, development failure, fixing failure, and photosensitive drum scratches caused by magnetic particles attached to the photoconductor. In addition, it is possible to prevent poor charging due to a reduction in magnetic particles, and to stably output a high-quality image. A process cartridge provided with a magnetic brush configured to contact magnetic particles constrained on the outer surface of a rotatable magnet member with the surface of a photoreceptor peels off the magnet member by a predetermined angle when removing the magnet from the image forming apparatus main body. The rotation can prevent the magnetic particles from adhering to the photoconductor. When one of the magnetic poles of the magnet member is arranged in a range of 1 degree to 15 degrees upstream from the line connecting the rotation center of the photoconductor and the rotation center of the conductive sleeve in the rotation direction of the photoconductor,
Increase the contact area of the magnetic particles to the photoconductor during charging,
Uniform charging becomes possible. When the rotation of the magnet member is stopped when the photoconductor is separated from the magnetic brush or when the process cartridge is removed from the image forming apparatus main body, one of the magnetic poles of the magnet member is stopped.
By arranging the magnetic particles near the line connecting the maximum spike length of the magnetic particles and the rotation center of the conductive sleeve, scattering of the magnetic particles can be prevented, and image defects and charging defects can be prevented. The peeling rotation operation of the conductive sleeve or the magnet member,
When interlocking with the separating operation of the magnetic brush and the photoconductor or the operation of taking out the process cartridge from the image forming apparatus main body, even if the user performs the separating operation or the taking out operation by mistake, the magnetic particles are not scattered, Image failure and charging failure can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a charging device and an image forming apparatus according to a first embodiment.

FIG. 2 is a diagram illustrating a peeling rotation operation and a separation operation of the magnetic brush according to the first embodiment.

FIG. 3 is a diagram illustrating a schematic configuration of a charging device and an image forming apparatus according to a second embodiment.

FIG. 4 is a diagram illustrating a peeling rotation operation and a separation operation of the magnetic brush according to the second embodiment.

FIG. 5 is a diagram illustrating a schematic configuration of a charging device and a drum unit according to a third embodiment.

FIG. 6 is a diagram illustrating a peeling rotation operation of a magnetic brush and a separating operation of a drum unit according to the third embodiment.

FIG. 7 is a diagram illustrating a schematic configuration of a process cartridge and an image forming apparatus according to a fourth embodiment.

FIG. 8 is a diagram illustrating a removal operation of a process cartridge according to a fourth embodiment.

FIG. 9 is a diagram showing a schematic configuration of a conventional charging member.

FIG. 10 is a view showing the operation of separating a conventional charging member from a photosensitive drum.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor (photosensitive drum) 2, 30, 52 Magnetic brush (charging device) 3 Conductive sleeve 5 D cut 6, 42, 46 Magnet member (magnet roller) 7 Magnetic particles 9 Exposure device (LED exposure device) 10 Developing device 13 Transfer device (transfer roller) 15 Fixing device 17 Cleaning device 20, 31 Upper cover 21 Image forming device 22 Hinge 23, 25 Gear 26, 65 Magnetic particle separation promoting mechanism (Rack plate) 26a Hook 26b Rack 27 Pressure spring 29 Positioning Pin 35 Magnetic particle separation acceleration mechanism (rotary lever) 66 Process cartridge

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-175468 (JP, A) JP-A-3-137665 (JP, A) JP-A-2-140767 (JP, A) JP-A-63- 307487 (JP, A) JP-A-5-216337 (JP, A) JP-A-7-72667 (JP, A) JP-A-6-266266 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/02 G03G 15/09

Claims (12)

(57) [Claims] 1. A magnet inside a rotatable conductive sleeve.
A magnet member, and the conductive member is provided by the magnet member.
The magnetic brush is constrained by the magnetic particles on the outer surface of the sleeve.
Formed and exposed at the contact area between the magnetic brush and the photoreceptor surface
Rotating the conductive sleeve in a direction opposite to the rotation of the body;
And applying a charging voltage to the conductive sleeve.
A charging device that charges the surface of the photoconductor, the magnetic brush and the photoconductor are separated during non-image formation.
A separating mechanism that causes the contact portion to perform a sensing operation prior to the separating operation performed by the separating mechanism.
Magnetic particles in the magnetic particle pool on the downstream side in the rotation direction of the optical bodyTo
FeelingThe conductive sleeve and the front so as to separate from the light body surface
At least one of the magnet members is at a predetermined angle
A magnetic particle separation promoting mechanism that rotates only the separation,With The magnetic brush and the photoconductor before the separating operation are separated from each other.
The rotation stop position of the gnet member is
One of the poles is the maximum spike length of the magnetic particles and the conductive stripe.
Place it near the line connecting the center of rotation of the leave,  A charging device, comprising: 2. The charging device according to claim 1, wherein the magnetic particle separation promoting mechanism separates and rotates the magnet member in the same direction as a rotation direction of the conductive sleeve during image formation. 3. The magnet member has a plurality of magnetic poles in a rotation direction of the conductive sleeve, and during a charging operation, causes one of the plurality of magnetic poles to move between a rotation center of the conductive sleeve and a photosensitive member. The charging device according to claim 1, wherein the charging device is disposed within a range of 1 ° to 15 ° on the upstream side in the rotation direction of the photoconductor from a line connecting the rotation center of the charging device. 4. The charging device according to claim 1, wherein the magnetic particle peeling promoting mechanism peels and rotates the conductive sleeve in a direction opposite to a rotation direction of the conductive sleeve during image formation. 5. A peeling rotational operation by the magnetic particles separation promoting mechanism, to synchronize with the detachment operation by the separation mechanism, one of claims 1 to 4, characterized in that 1
Item 2. The charging device according to item 1. 6. An image forming apparatus which is detachably mounted on an image forming apparatus main body.
A process cartridge to be mounted on
A magnet member is placed inside the rollable conductive sleeve
And the outside of the conductive sleeve is formed by the magnet member.
A magnetic brush is formed by binding magnetic particles to the surface, and the magnetic brush is formed.
The contact between the air brush and the surface of the photoconductor
Rotate the conductive sleeve in the opposite direction
By applying a charging voltage to the conductive sleeve,
A process integrally comprising a charging device for charging the surface
In the cartridge, the process cartridge is removed from the image forming apparatus main body.
Prior to taking out, downstream of the contact portion in the photoconductor rotation direction
Magnetic particles in the magnetic particle pool on the sideFeelingPeel from the surface of the light body
The conductive sleeve and the magnet member are separated from each other.
At least one of peeling and rotating by a predetermined angle
Magnetic particle separation acceleration mechanismPrepared, The process cartridge from the image forming apparatus main body
Of rotation of the magnet member before the take-out operation
The position is determined by one of the magnetic poles of the magnet member.
Between the maximum spike length of the conductive particles and the center of rotation of the conductive sleeve.
Placed near the center of the  A process cartridge characterized by the above-mentioned. 7. The process cartridge according to claim 6, wherein the magnetic particle separation promoting mechanism separates and rotates the magnet member in the same direction as the rotation direction of the conductive sleeve during image formation. 8. The magnetic member has a plurality of magnetic poles in a rotation direction of the conductive sleeve, and during a charging operation, causes one of the plurality of magnetic poles to move between a rotation center of the conductive sleeve and a photosensitive member. the process cartridge from the line connecting the center of rotation, is arranged within a range of 15 degrees 1 degree on the upstream side of the photosensitive member rotation direction, of claim 6 or claim 7, wherein the. 9. The process cartridge according to claim 6, wherein the magnetic particle separation promoting mechanism separates and rotates the conductive sleeve in a direction opposite to a rotation direction of the conductive sleeve during image formation. The method according to claim 10 peeling rotational operation by the magnetic particles peeling promoter mechanism, the image forming apparatus is interlocked to the take-out operation of the process cartridge from the main body, one of claims 6 to 9, characterized in that 1
The process cartridge according to the item. 11. A photosensitive member, a charging device according to any one of claims 1 to 5, an exposure device for forming an electrostatic latent image by exposing the photosensitive member after charging, the electrostatic latent An image forming apparatus comprising: a developing device that forms a toner image by attaching toner to an image; and a transfer device that transfers the toner image onto a transfer material. 12. comprises the image forming apparatus main body, and a process cartridge according to any one of claims 6 to 10, that the image forming apparatus according to claim.