JPH11352749A - Electrifying brush mechanism, electrophotographic cartridge, electrophotographic recording unit and electrophotographic recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a faulty image from being formed due to an undesirable curling of the bristles of a brush because an electrifying brush roller is reversely rotated when the rotation thereof is stopped and to realize mechanical removing of the soil of the electrifying brush roller by a simple mechanism. SOLUTION: The electrifying brush roller 14 is driven by a motor 30 through a gear 15, a reverse rotation preventing gear 16 and a gear 17. The gear 16 is constituted of a gear 18 having a projection part and a gear 19 having a recessed part where the projection part enters. The recessed part is formed to be a long hole in the circumferential direction and provided with a play between the projection part. Thus, even in the case that reverse rotating force is generated when the rotation of the motor 30 is stopped, it is absorbed by the play and the roller 14 is not reversely rotated. When the motor 30 is started to be rotated, the rotation start time of the roller 14 is delayed with respect to a photoreceptor 12 and the brush temporarily bristles up. Thus, the soil is mechanically eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging brush mechanism, an electrophotographic cartridge, an electrophotographic recording unit, and an electrophotographic recording apparatus, and more particularly, to a charging brush mechanism for charging a surface of an electrophotographic photosensitive member with a brush, and the charging brush. The present invention relates to an electrophotographic cartridge having a mechanism, an electrophotographic recording unit, and an electrophotographic recording device.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic recording apparatus forms an image by using an image carrier such as a photoreceptor by a process of charging, exposing, developing, transferring and fixing. As a method for charging the photoreceptor, a corona discharge device has been widely used. Since the corona discharge device has a problem of generating ozone by performing corona discharge, in recent years, a contact charging method in which a charging member capable of suppressing generation of ozone is brought into contact with a member to be charged to perform charging is widely used. Have been. As one of the contact charging systems, there is a brush charging system using a charging brush roller.

In the brush charging system, the charging brush roller may rotate in the reverse direction after the completion of the image forming process. When the charging brush roller rotates in the reverse direction, the hair of the brush is stopped for a long time while being in contact with the photoreceptor in an upright state, so that the hair has a habit. If the hair has a habit, in a subsequent image forming process, uneven contact with the photoreceptor causes uneven charging and adversely affects the image. In addition, since the load applied to the photoconductor varies, pitch unevenness in an image occurs due to rotation unevenness of the photoconductor.

Since the charging brush roller becomes dirty during use and adversely affects an image, it is necessary to mechanically remove the dirt. When the bristles of the brush temporarily rotate reversely with respect to the photoconductor at the start of rotation, the bristles of the brush stand upright and can remove dirt.

In order to prevent reverse rotation of the charging brush roller, the backlash between the gears for driving the charging brush roller is compared with a standard value shown in FIG.
Enlarging is performed as shown in FIG. At this time, the mesh between the gears deteriorates, and tooth skipping is likely to occur. Further, when a large load is applied, the gear teeth may be shaved and, in the worst case, broken.

To prevent such a problem from occurring, there is a measure to use a one-way clutch or the like. However, since the one-way clutch rotates only in one direction, it does not reversely rotate even when a reverse rotation force is applied. It has a simple structure. Therefore, there is no effect of removing dirt on the charging brush roller at the start of rotation.

[0007]

In the conventional charging brush mechanism described above, in the system in which the backlash between the gears for driving the charging brush roller is made larger than the standard, tooth backlash occurs and the teeth break. There is a problem that an adverse effect on an image occurs.

Further, in the method using a one-way clutch, there is no effect of removing dirt from the charging brush roller, so that the life of the charging brush roller is shortened. Further, since the one-way clutch is expensive, the apparatus is expensive. However, there is a problem that the cost increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a charging brush mechanism, an electrophotographic cartridge, and an electrophotographic apparatus which can prevent the brush hairs of the charging brush roller from sticking and remove dirt with a simple mechanism. It is to provide a recording unit and an electrophotographic recording device.

[0010]

According to the present invention, there is provided a charging brush mechanism comprising: a charging brush roller for charging a photoreceptor; and a gear train for transmitting rotation of a driving motor to a shaft of the charging brush roller. Includes a first gear having a convex portion on a side surface and a reverse rotation preventing gear formed by combining a second gear having a concave portion into which the convex portion enters, wherein the first gear and the second gear are , Characterized by having play in the rotation direction.

[0011] In the charging brush mechanism of the present invention, the recess may be formed as an elongated hole in a circumferential direction of the second gear.

[0012] In the charging brush mechanism of the present invention, the play between the first gear and the second gear may be larger than the backlash of a gear train that transmits the rotation of the drive motor to the reverse rotation preventing gear. It may be.

An electrophotographic cartridge according to the present invention includes a photosensitive member, a charging brush roller for charging the photosensitive member, and a gear train for transmitting rotation of a driving motor to a shaft of the charging brush roller. A first gear having a convex portion on a side surface, and a reverse rotation preventing gear formed by combining a second gear having a concave portion into which the convex portion enters, wherein the first gear and the second gear are It is characterized by having play in the rotation direction.

In the electrophotographic cartridge of the present invention, the drive motor for the photosensitive member and the drive motor for the charging brush roller may be the same.

An electrophotographic recording unit according to the present invention comprises a photosensitive member, a charging brush roller for charging the photosensitive member, a driving motor for rotating the charging brush roller, and a rotation of the driving motor on a shaft of the charging brush roller. The gear train includes a first gear having a convex portion on a side surface, and a reverse rotation preventing gear formed by combining a second gear having a concave portion into which the convex portion enters, The first gear and the second gear have a play in a rotational direction.

An electrophotographic recording apparatus according to the present invention comprises: a photosensitive member;
A charging brush roller for charging the photoconductor, a drive motor for rotating the charging brush roller, and a gear train for transmitting rotation of the drive motor to a shaft of the charging brush roller, wherein the gear train is provided on a side surface. A first gear having a convex portion, and a second gear having a concave portion into which the convex portion is inserted, including a reverse rotation preventing gear, wherein the first gear and the second gear are arranged in a rotational direction. It is characterized by having play.

[0017]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of the electrophotographic recording apparatus of the present invention. 2. Description of the Related Art An electrophotographic recording apparatus is an apparatus that forms an image using an electrophotographic method, and is used for a printer, a plotter, a copying machine, a facsimile machine, and the like.

The paper 1 is guided to an electrophotographic recording unit 4 by a paper feed roller 2 and a guide roller 3 to form an image, and is discharged out of the apparatus by a discharge roller 5. Control unit 6
Controls these mechanisms. Although not shown, in addition to this configuration, a printer, plotter, or facsimile machine has an external interface unit, and a copier has a document reading unit.

The electrophotographic recording unit 4 is a unit for forming an image by using an electrophotographic method, and includes an electrophotographic cartridge 7, a light source 8, a transfer roller 9, a fixing device 10, and a motor 30.

FIG. 2 shows an electrophotographic cartridge 7 and a motor 3.
FIG. 3 is a sectional view of the electrophotographic cartridge 7. The electrophotographic cartridge 7 includes a developing unit 11 and a photoconductor 1.
2, a waste toner collecting unit 13, a charging brush roller 14, a gear 15 for driving the charging brush roller 14, a reverse rotation preventing gear 16, and a gear 17. The developing unit 11 includes a stirrer 20, a toner supply roller 21, a developing roller 22, and a toner layer regulating member 23. The motor 30 drives the rotation of the electrophotographic cartridge 7.

The charging brush roller 14 is obtained by implanting conductive bristle brush fibers on the roller surface. The bristle brush fibers include rayon, polypropylene, acrylic, nylon, and the like.
Polyester, polycarbonate, polyvinyl alcohol and the like are used.

By the rotation of the motor 30, the rotation is transmitted in the order of the gear 15, the reverse rotation preventing gear 16, and the gear 17, and the charging brush roller 14 rotates. At this time, the peripheral speed ratio of the charging brush roller 14 to the photosensitive member 12 is 5.5. The peripheral speed ratio of the charging brush roller 14 to the photoconductor 12 may be larger than 1.

The reverse rotation preventing gear 16 is composed of the gear 18 and the gear 1.
9. 4 is a perspective view of the gear 18, FIG. 5 is a perspective view of the gear 19, and FIG. 6 is a cross-sectional view of the reverse rotation preventing gear 16 in which the gear 18 and the gear 19 are combined. Referring to FIG. 4, the gear 18 has four convex portions 18a on the side surface. Referring to FIG. 5, the gear 19 is a protrusion 18 of the gear 18.
a has a concave portion 19a on the side surface. Recess 19 of gear 19
a is a long hole in the circumferential direction. Referring to FIG. 6, since the concave portion 19a of the gear 19 has a long hole with respect to the circumferential direction, when the convex portion 18a of the gear 18 is combined, rattling occurs in the circumferential direction. At this time, the moving amount of the convex portion 18a in the concave portion 19a depends on the gear 1 in the reverse rotation preventing gear 16.
The amount of backlash between the gear 8 and the gear 15 on the motor 30 side engaged with the reverse rotation preventing gear 16 is larger than the amount of backlash.

In the present embodiment, an example has been described in which the convex portion 18a of the gear 18 and the concave portion 19b of the gear 19 are four.
The number is not limited to four, but may be at least one. For example, it can be provided in 6 to 8 places and can be used in places with a larger load.

Next, the operation will be described. First, an outline of the operation of the electrophotographic recording unit 4 will be described with reference to FIGS.

The surface of the photoreceptor 12 is charged by a charging brush roller 14. The photoconductor 12 is exposed to light from the light source 8 to form a latent image. The formed latent image is developed
The first developing roller 22 develops with toner. Developing unit 1
In 1, the developer and the toner are agitated by the stirrer 20, the toner is supplied to the developing roller 22 by the toner supply roller 21, and the toner layer on the developing roller 22 is made to have a predetermined thickness by the toner layer regulating member 23. To be regulated.

The toner image on the photosensitive member 12 is transferred to the sheet 1 by the transfer roller 9. The toner remaining on the photoconductor 12 without being transferred is collected by a waste toner collecting unit 13. The toner image on the sheet 1 is fixed by the fixing device 10.

Next, the operation of the charging brush roller 14 will be described. When the motor 30 rotates, the gear 15 in the electrophotographic cartridge 7 rotates, and the gear 18 in the reverse rotation preventing gear 16 rotates. Next, another gear 19 in the reverse rotation preventing gear 16 is rotated from the gear 18, and further, the gear 17 of the charging brush roller 14 is rotated from the gear 19. At this time, the reverse rotation preventing gear 16
There is play in the convex portion 18a of the gear 18 and the concave portion 19a of the gear 19, and even if a reverse rotation force acts when the motor 30 stops, the reverse rotation prevention gear 16 absorbs the reverse rotation force, The gear 17 of the charging brush roller 14 is not reversely rotated.

Even if the motor 30 rotates again and the gear 15 and the gear 18 in the reverse rotation preventing gear 16 start to rotate, the convex portion 18a of the gear 18 and the concave portion 19a of the gear 19 in the reverse rotation preventing gear 16 remain. Because there is play, the charging brush roller 14
Does not start spinning. On the other hand, the photoconductor 12 is
It starts rotating at the same time as the start of 0. As the photoconductor 12 starts to rotate earlier than the charging brush roller 14, the bristles 14a of the charging brush roller 14 are turned upside down by the photoconductor 12 as shown in FIG. At this time, dirt on the charging brush roller 14 can be mechanically removed. When the play between the convex portion 18a of the gear 18 and the concave portion 19a of the gear 19 in the reverse rotation preventing gear 16 is absorbed and the charging brush roller 14 starts rotating, the peripheral speed of the charging brush roller 14 becomes the peripheral speed of the photoconductor 12. As shown in FIG. 7, the bristles 14a of the charging brush roller 14
The reverse hair disappears.

[0030]

As described above, according to the present invention, the backlash in the reverse rotation preventing gear prevents the charging brush roller from rotating in the reverse direction even when a reverse rotation force acts on the gear when stopped. It is possible to prevent the brush brushes from being upright due to the reverse rotation of the charging brush roller at the time of stoppage, to reduce rotation unevenness due to the brush brush's bristles occurring during reprinting, and to perform uniform charging. effective.

Further, at the start of rotation, there is an effect that the brush bristles are temporarily turned upside down, so that dirt on the charging brush roller can be mechanically removed, and the life of the charging brush roller is prolonged. .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an electrophotographic recording apparatus of the present invention.

FIG. 2 is a perspective view of an electrophotographic cartridge and a motor.

FIG. 3 is a sectional view of the electrophotographic cartridge.

FIG. 4 is a perspective view of a gear having a convex portion among the reverse rotation preventing gears.

FIG. 5 is a perspective view of a gear having a concave portion in the reverse rotation preventing gear.

FIG. 6 is a sectional view of a reverse rotation preventing gear.

FIG. 7 is a diagram illustrating a state of hair when the charging brush roller rotates.

FIG. 8 is a diagram illustrating a state in which the bristle of the charging brush roller is upright.

FIG. 9 is a diagram showing a backlash of a conventional gear.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 paper 2 paper feed roller 3 guide roller 4 electrophotographic recording unit 5 discharge roller 6 control unit 7 electrophotographic cartridge 8 light source 9 transfer roller 10 fixing device 11 developing unit 12 photoconductor 13 waste toner collecting unit 14 charging brush roller 14a bristle 15 Gear 16 Reverse rotation prevention gear 17 Gear 18 Gear 18a Convex portion 19 Gear 19a Concave portion 20 Stirrer 21 Toner supply roller 22 Developing roller 23 Toner layer regulating member 30 Motor

Claims (12)

[Claims] 1. A charging device comprising: a charging brush roller for charging a photoreceptor; and a gear train for transmitting rotation of a driving motor to a shaft of the charging brush roller, wherein the gear train has a first gear having a convex portion on a side surface. And a second gear having a concave portion into which the convex portion is inserted.
Wherein the gear and the second gear have a play in the rotation direction. 2. The charging brush mechanism according to claim 1, wherein the concave portion has a long hole in a circumferential direction of the second gear. 3. The backlash between the first gear and the second gear is larger than the backlash of a gear train that transmits the rotation of the drive motor to the reverse rotation prevention gear. 3. The charging brush mechanism according to 1 or 2. 4. A photoconductor, a charging brush roller for charging the photoconductor, and a gear train for transmitting rotation of a driving motor to a shaft of the charging brush roller, wherein the gear train has a convex portion on a side surface. And a second gear having a concave portion into which the convex portion is inserted. The first gear and the second gear have a play in the rotational direction. An electrophotographic cartridge characterized by the above-mentioned. 5. The electrophotographic cartridge according to claim 4, wherein said concave portion has an elongated hole in a circumferential direction of said second gear. 6. The backlash between the first gear and the second gear is larger than a backlash of a gear train transmitting the rotation of the drive motor to the reverse rotation preventing gear. The electrophotographic cartridge according to 4 or 5. 7. The electrophotographic cartridge according to claim 4, wherein the drive motor of the photosensitive member and the drive motor of the charging brush roller are the same. 8. A photoconductor, a charging brush roller for charging the photoconductor, a driving motor for rotating the charging brush roller, and a gear train transmitting rotation of the driving motor to a shaft of the charging brush roller. The gear train includes a first gear having a convex portion on a side surface, and a reverse rotation preventing gear formed by combining a second gear having a concave portion into which the convex portion enters. The electrophotographic recording unit, wherein the second gear has a play in the rotation direction. 9. The electrophotographic recording unit according to claim 8, wherein the concave portion has a long hole in a circumferential direction of the second gear. 10. A backlash between the first gear and the second gear is larger than a backlash of a gear train transmitting the rotation of the drive motor to the reverse rotation preventing gear. 10. The electrophotographic recording unit according to 8 or 9. 11. The electrophotographic recording unit according to claim 8, wherein the drive motor drives the photoconductor in addition to driving the charging brush roller. 12. An electrophotographic recording apparatus comprising the electrophotographic recording unit according to claim 8, 9, 10, or 11.