JPH06208304A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent the stripe of an image or the unevenness of development caused by the defective recovery of toner by sticking developer to an eletrostatic latent image holding body having a fixed magnet, carrying and feeding it to an electrode roller part impressing AC bias thereon and removing toner in a non-image part by electrostatic force and magnetic force. CONSTITUTION:An electrostatic latent image is formed by irradiating a photosensitive body 14 with a laser beam 18, and magnetic component toner is stuck to the image by the magnetic force of the magnet 15 in the photosensitive body 14 in a developer storage 19 Then, the photosensitive body 14 is allowed to pass before an electrode roller 21. A toner layer moves between the photosensitive body 14 and the roller 21, and the toner in the non-image part is gradually shifted to the roller 21 side, then a toner image inverted from negative to positive remains only in an image part on the photosensitive body 14. The toner stuck to the roller 21 forms a magnetic brush along magnetic field in the peripheral direction of the roller 21 by the magnet 22 and wholy fed as the magnetic brush by frictional force by the rotation of the roller 21 scraped by a scraper 24, and restored to the developer storage 19, then the roller 21 is used for next image forming again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus applicable to printers, facsimiles and the like.

[0002]

2. Description of the Related Art Conventionally, a two-component developing method using a developer composed of a toner and a carrier has been widely used in an electrophotographic method, but in recent years, a one-component developing method has been used in order to reduce the size of an image forming portion and reduce the cost. Is being developed. As an electrophotographic apparatus using such a one-component developing method, there is an apparatus shown in FIG. 11 proposed by the applicants in Japanese Patent Application No. 3-345990. In FIG. 11, 1 is an organic photosensitive drum in which phthalocyanine is dispersed in a polyester binder resin, 2
Is a magnet fixed coaxially with the photoconductor 1. 3 is a corona charger for charging the photosensitive member, 4 is a grid electrode for controlling the charging potential of the photosensitive member, 5 is signal light, 6 is a developer reservoir, 7 is a magnetic one-component toner, and 8 is a developer reservoir. This is a damper for smoothing the flow of the developer and preventing the developer from being crushed by its own weight and clogged between the photoconductor and the electrode roller. The magnet 2 faces the developer reservoir 6 (θ =
The magnetic pole is formed at the 10 ° portion. Reference numeral 9 is an aluminum electrode roller having a magnet 10 inside, 11 is an AC high voltage power source for applying a voltage to the electrode roller, 12 is a scraper made of a polyester film for scraping off the toner on the electrode roller, and 13 is toner on the photoconductor. A transfer corona charger that transfers an image to paper.

This electrophotographic developing device is shown in FIG.
The operation will be described using 1. The photoconductor 1 was charged to −500V by the corona charger 3. The photoconductor 1 was irradiated with laser light 5 to form an electrostatic latent image. Toner 7 was attached to the surface of the photoconductor 1 in the developer reservoir 6 by magnetic force. Next, the photoconductor 1 was passed in front of the electrode roller 9. At this time, -3 is applied to the electrode roller 9 by the AC high voltage power supply 11.
An AC voltage of 750 V 0-p (frequency 1 kHz) superposed with a DC voltage of 50 V was applied. Then, the toner was collected from the photoconductor 1 toward the electrode roller 9, and the negative-positive inverted toner image remained only on the image portion on the photoconductor 1. The toner adhering to the electrode roller 9 rotating in the direction of the arrow was scraped off by the scraper 12, returned to the developer reservoir 6 and used for the next image formation. The toner image thus obtained on the photoconductor 1 was transferred onto paper (not shown) by the transfer charger 13 and then thermally fixed by a fixing device (not shown).

[0004]

When the electrophotographic developing apparatus as described above is used to print under conditions of high temperature and high humidity (33 ° C., 85% RH), the problem that the background fog increases gradually occurs in the image. It was

An object of the present invention is to remove the toner collected on the electrode roller from the developing field promptly in an electrophotographic developing apparatus of the type in which the magnetic toner attached to the entire surface of the photoconductor is collected and developed by a bare electrode roller. Another object of the present invention is to provide an electrophotographic apparatus that prevents image streaks and development unevenness due to poor toner recovery and can stably obtain high-resolution, high-quality images without background fog. It also provides an excellent electrophotographic apparatus that can be used in high-speed processes.

[0006]

According to the present invention, there is provided an electrostatic latent image holding member which contains and moves a fixed magnet, a magnetic developer, and an opening portion facing the fixed magnet. A developer reservoir for supplying a magnetic developer to the surface of the holding body, and a position provided with a predetermined gap from the surface of the electrostatic latent image holding body,
An electrode roller whose traveling direction rotates in a direction opposite to the traveling direction of the electrostatic latent image holding member; and means for applying a voltage for removing the toner in the non-image portion on the electrostatic latent image holding member to the electrode roller. A magnetic field generating means for generating a magnetic field in the circumferential direction of the electrode roller at the surface position of the electrode roller.

In the present invention, an electrostatic latent image carrier that contains a fixed magnet A and moves, a magnetic developer, and a developer reservoir for supplying the magnetic developer to the surface of the electrostatic latent image carrier. An electrode roller which is installed at a position having a predetermined gap from the surface of the electrostatic latent image holder, includes a fixed magnet B, and rotates in a traveling direction opposite to the traveling direction of the electrostatic latent image holder. And a means for applying a voltage for removing the toner in the non-image area on the electrostatic latent image carrier to the electrode roller, and the fixed magnet B has a magnetic flux having a plurality of peaks on the surface of the electrode roller. The electrophotographic apparatus is characterized in that a density distribution is generated, and magnetic flux density peaks adjacent to each other in the circumferential direction of the electrode roller have mutually opposite polarities.

Furthermore, the present invention is directed to an electrostatic latent image holding member that moves by containing a fixed magnet A, a magnetic developer, and a developer reservoir for supplying the magnetic developer to the surface of the electrostatic latent image holding member. And a fixed magnet B and a magnetic body are included inside, and the traveling direction is opposite to the traveling direction of the electrostatic latent image holder. An electrophotographic apparatus comprising: an electrode roller that rotates in a direction; and a unit that applies a voltage for removing toner in a non-image portion on the electrostatic latent image holding member to the electrode roller.

Furthermore, the present invention includes an electrostatic latent image holding member that moves by containing a fixed magnet, a magnetic developer, and a developer reservoir for supplying the magnetic developer to the surface of the electrostatic latent image holding member. An electrode roller which is installed at a position having a predetermined gap from the surface of the electrostatic latent image holding member and which rotates in a direction opposite to the moving direction of the electrostatic latent image holding member; The electrophotographic apparatus is characterized in that it has means for applying a voltage for removing the toner in the non-image area on the holder to the electrode roller, and means for improving the frictional force against the toner on the surface of the electrode roller.

Furthermore, the present invention comprises an electrostatic latent image carrier that contains a fixed magnet and moves, a magnetic developer, and a developer reservoir for supplying the magnetic developer to the surface of the electrostatic latent image carrier. An electrode roller which is installed at a position having a predetermined gap from the surface of the electrostatic latent image holding member and which rotates in a direction opposite to the moving direction of the electrostatic latent image holding member; An electrophotographic apparatus comprising: a means for applying a voltage for removing toner in a non-image area on a holding body to the electrode roller, and providing a conductive resin layer on the surface of the electrode roller.

[0011]

According to the present invention, an electrostatic latent image holder containing a fixed magnet is used, and a developer is sprinkled and magnetically adhered to the electrostatic latent image holder on which an electrostatic latent image is formed, and the electrostatic latent image carrier is carried to the electrode roller portion. This is an improved configuration of an electrophotographic apparatus in which the toner is conveyed, an AC bias is applied to the electrode roller, and the non-image portion toner of the electrostatic latent image holding member is removed by electrostatic force and magnetic force.

In the present invention, by newly providing a means for rapidly conveying and collecting the magnetic developer collected on the surface of the electrode roller to the developer reservoir, the toner collected on the electrode roller stays in the developing field. Since it can be removed quickly without performing, the high image quality can be obtained without causing fog even in high humidity conditions where the fluidity of the toner is lowered or in a high speed process. In the present invention, by providing the magnetic field generating means for generating the magnetic field in the circumferential direction of the electrode roller at the surface position of the electrode roller, the magnetic brush of toner is formed in the circumferential direction of the electrode roller as shown in FIG. Since the carrying force of the electrode roller acts on the entire magnetic brush, not on the first layer of toner that comes into direct contact with the surface of the electrode roller, the toner recovery capability is significantly improved. The uneven transport due to the variation in the frictional force is eliminated. Therefore, since the low-charged toner collected by the electrode roller can be strongly and uniformly removed from the vibration region due to the AC bias, high image quality can be obtained without causing fog and uneven density even under high humidity conditions or high-speed processes. .

Further, according to the present invention, a fixed magnet is provided inside the electrode roller such that the magnets adjacent to each other in the circumferential direction of the electrode roller have opposite polarities, so that a plurality of magnetic flux density distributions are formed at the surface position of the electrode roller. A magnetic field appears, along which the toner forms a magnetic brush.
As a result, the direction of the magnetic brush of the toner changes abruptly at the peak of the magnetic flux density on the surface of the electrode roller, and the toner is disturbed and is easily charged by friction with the electrode roller. This action not only removes the low-charged toner collected on the electrode roller from the developing area, but also imparts an electric charge at the same time. Therefore, even in high humidity conditions or high-speed processes, background fog and density unevenness do not occur. Is obtained.

Further, in the present invention, by making a part of the magnetic poles of the fixed magnet inside the electrode roller a magnetic body, it becomes easier to concentrate the lines of magnetic force as compared with the case where only the magnet is formed, and the magnetic field appearing on the surface of the electrode roller is stronger. Therefore, the transporting ability and the charging ability can be further improved. Further, the magnetic pole structure of the fixed magnet can be simplified and the cost can be reduced.

Further, according to the present invention, by providing a means for improving the frictional force with the toner on the surface of the electrode roller, the carrying force of the toner collected by the electrode roller is increased, so that it can be used under high humidity condition or high speed process. It is possible to obtain high image quality without causing fog and uneven density. The improvement of the frictional force with the toner can be achieved by forming fine grooves on the surface of the electrode roller or by performing a blast treatment. For example, by blasting the surface roughness to Ra 0.5 or more, the toner collected by the electrode roller can be more sufficiently transported as the electrode roller rotates without slipping.

Further, in the present invention, it has been found that the frictional force with the toner is increased by providing the conductive resin layer on the surface of the electrode roller. If the electrode roller surface is not a conventional metal surface such as stainless steel or aluminum, but a resin layer with a higher frictional resistance is provided, the collected toner can be conveyed along with the rotation of the electrode roller without slipping. .

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrophotographic apparatus of the present invention will be described below with reference to the drawings.

(Specific Embodiment 1) FIG. 1 shows an embodiment of the electrophotographic apparatus of the present invention. In FIG. 1, 1
4 is an organic photosensitive drum (diameter 30 mm) in which phthalocyanine is dispersed in a polyester binder resin, and the peripheral speed is 30
It was rotated at mm / s. Reference numeral 15 is a magnet fixed coaxially with the photoconductor 14, and the peak of the magnetic flux density on the surface of the photoconductor 14 is -8.
00 Gs (S pole). 16 is a corona charger for negatively charging the photoconductor 14, 17 is a grid electrode for controlling the charging potential of the photoconductor 14, 18 is a signal light, 19 is a developer reservoir, 20 is a negative chargeability of an average particle diameter of about 12 μm. It is a magnetic one-component toner. Reference numeral 21 denotes an aluminum electrode roller (diameter 16 mm), which has a peripheral speed of 30 in the direction opposite to that of the photoconductor 14.
It was rotated at mm / s. Reference numeral 22 denotes a magnet having two magnetic poles fixed coaxially with the electrode roller 21, and 23 denotes the electrode roller 21.
AC high-voltage power supply for applying voltage to the electrode roller 24
A scraper made of a polyester film that scrapes off the above toner, and 25 is a transfer corona charger that transfers the toner image on the photoconductor 14 onto paper. Reference numeral 26 is a cleaner for cleaning the remaining toner after the toner on the photoconductor 14 is transferred.

The vertical magnetic flux density distribution of the magnet 22 on the surface of the electrode roller 21 is shown in FIG. The peak of magnetic flux density is 6
00 Gs (N pole) and -350 Gs (S pole). The magnet 22 inside the electrode roller 21 and the magnet 1 inside the photoconductor 14
The positional relationship with No. 5 is shown in FIG. Magnet 1 inside the photoconductor 14
The angle 5 is θ from the position facing the electrode roller 21 toward the upstream side.
It was set to 1 = 35 °. Magnet 22 inside electrode roller 21
The N pole was set to θ2 = −15 ° and the S pole was set to θ3 = + 20 °. The range of θ1 is preferably 0 ° <θ1 <45 °, and particularly preferably the range of 10 ° <θ1 <40 °. θ
2 is preferably in the range of -20 ° <θ <0 °, particularly -15
The range of ° <θ <-10 ° is optimal. θ3 is 0 ° <θ
A range of <90 ° is preferable, and a range of 10 ° <θ <50 ° is particularly preferable.

The magnetic one-component toner used is composed of 70% of polyester resin, 25% of ferrite, 3% of carbon black and 2% of metal complex of oxycarboxylic acid, and 0.4% of colloidal silica is externally added. (All were weight%).

The operation of the electrophotographic apparatus configured as described above will be described below with reference to FIG. Photoconductor 1
4 is a corona charger 16 (applied voltage-4 kV, grid 17
Of -500V) was charged to -500V. The photoconductor 14 was irradiated with laser light 18 to form an electrostatic latent image. At this time, the exposure potential (Vr) of the photoconductor 14 is -100.
It was V. On the surface of the photoconductor 14, magnetic one-component toner is attached in the developer reservoir 19 by the magnetic force of the magnet 15 in the photoconductor 14. At this time, the toner is approximately -3 μC / g
Was charged to. Next, the photoconductor 1 to which this toner layer is attached
4 was passed in front of the electrode roller 21. The electrode roller 21 was installed at a distance of 300 μm from the photoconductor 14.
A high voltage power supply 23 applied to the electrode roller 21 an alternating voltage (frequency: 1 kHz) of 750 V 0-p having a waveform shown in FIG. The toner layer on the photoconductor 14 moves between the photoconductor 14 and the electrode roller 21,
The toner in the non-image portion gradually moved to the electrode roller 21 side, and the negative-positive inverted toner image remained only on the image portion on the photoconductor 14. The toner attached on the electrode roller 21 rotating in the direction of the arrow forms a magnetic brush along the magnetic field in the circumferential direction of the electrode roller 21 by the magnet 22 inside the electrode roller 21, and the frictional force due to the rotation of the electrode roller 21 is generated. The magnetic brush was conveyed, scraped off by the scraper 24 and returned to the developer reservoir 19, and the electrode roller 21 was used again for the next image formation. It was observed that the toner was violently disturbed above the S pole inside the electrode roller 21.
After the toner image thus obtained on the photoconductor 14 is transferred onto a paper (not shown) by the transfer corona charger 25,
Heat fixing was performed by a fixing device (not shown). As a result, a sharp image with no background fog or image unevenness was obtained.
On the other hand, the toner remaining on the photoconductor 14 after transfer is the photoconductor 14
Are conveyed by the movement of the cleaner and collected by the cleaner 26.

(Specific Embodiment 2) The structure of FIG. 6 is the same as the structure of FIG. 1 except that the magnet 22 is fixed inside the electrode roller 21 coaxially with the electrode roller 21, and the magnetic plate 27 is fixed on the magnet 22. Is different. Other configurations are the same as those in FIG.

Electrode roller 2 of magnet 22 and magnetic plate 27
FIG. 7 shows the magnetic flux density distribution in the vertical direction on one surface. The peak of magnetic flux density is 600 Gs (N pole) and -200 Gs
(Magnetic plate). The positional relationship between the magnet 22 inside the electrode roller 21 and the magnet 15 inside the photoconductor 14 is shown in FIG. The angle of the magnet 15 inside the photoconductor 14 was set to θ1 = 35 ° upstream from the position facing the electrode roller 21. The north pole of the magnet 22 inside the electrode roller 21 was set to θ2 = −15 °, and the magnetic plate was set to θ3 = + 15 °. The range of θ1 is 0 ° <
θ1 <45 ° is preferable, and the range of 10 ° <θ1 <40 ° is most preferable. θ2 is preferably in the range of −20 ° <θ <0 °, and particularly preferably in the range of −15 ° <θ <-10 °. θ3 is preferably in the range of 0 ° <θ <90 °, and particularly preferably in the range of 10 ° <θ <50 °.

The operation of the electrophotographic apparatus configured as described above will be described below with reference to FIG. Photoconductor 1
4 is a corona charger 16 (applied voltage-4 kV, grid 17
Of -500V) was charged to -500V. The photoconductor 14 was irradiated with laser light 18 to form an electrostatic latent image. At this time, the exposure potential of the photoconductor 14 was −100V. On the surface of the photoconductor 14, magnetic one-component toner is attached in the developer reservoir 19 by the magnetic force of the magnet 15 in the photoconductor 14. Next, the photoconductor 14 having the toner layer attached thereto was passed in front of the electrode roller 21. A high voltage power supply 23 is applied to the electrode roller 21 by an AC voltage of 750V0-p (frequency: 1kHz) having a waveform shown in FIG.
Was applied. The toner layer on the photoconductor 14 moves between the photoconductor 14 and the electrode roller 21, so that the toner in the non-image area gradually moves to the electrode roller 21 side, and the toner image on the photoconductor 14 is negative-positive inverted only in the image area. Remained. The toner adhered on the electrode roller 21 rotating in the direction of the arrow forms a magnetic brush along the magnetic field in the circumferential direction of the electrode roller 21 by the fixed magnet 22 and the magnetic plate 27 inside the electrode roller 21, and the toner of the electrode roller 21 moves. The magnetic brush was conveyed together with the frictional force due to the rotation, scraped by the scraper 24, returned to the developer reservoir 19 and used for the next image formation.
It was found that the toner was violently disturbed above the magnetic plate 27 in the electrode roller 21. The toner image thus obtained on the photoconductor 14 was transferred onto paper (not shown) by the transfer corona charger 25, and then thermally fixed by a fixing device (not shown). As a result, a sharp image with no background fog or image unevenness was obtained. On the other hand, the toner remaining on the photoconductor 14 after the transfer is conveyed by the movement of the photoconductor 14 and is collected by the cleaner 26.

(Specific Embodiment 3) An embodiment at a high print speed will be described below. FIG. 9 shows a process speed of 18
It is a device of 0 mm / s, and its configuration is the same as that of FIG.
The magnet inside the electrode roller 21 is different. Furthermore, as shown in FIG. 10, the surface of the electrode roller 21 is different in that fine grooves are provided parallel to the axial direction. The operation of the electrophotographic apparatus configured as described above will be described below with reference to FIG. The photoconductor 14 is charged with a corona charger 16 (applied voltage-
6kV, voltage of grid 17 -500V), -500V
Charged to. The photoconductor 14 was irradiated with laser light 18 to form an electrostatic latent image. At this time, the exposure potential of the photoconductor 14 was −100V. On the surface of the photoconductor 14, magnetic 1
The component toner is stored in the developer reservoir 19 and the magnet 15 in the photoconductor 14 is held.
It is attached by the magnetic force of. Next, the photoconductor 14 having the toner layer attached thereto was passed in front of the electrode roller 21. A high voltage power supply 23 is applied to the electrode roller 21 so that the waveform shown in FIG.
An AC voltage of 750V0-p (frequency: 3kHz) superposed with a DC voltage of -300V was applied. The toner layer on the photoconductor 14 moves between the photoconductor 14 and the electrode roller 21, and the toner in the non-image area gradually moves to the side of the electrode roller 21.
On No. 4, a negative-positive inverted toner image remained only in the image area. The toner adhering to the electrode roller 21 rotating in the direction of the arrow is conveyed by the groove on the surface of the electrode roller 21 without a strong frictional force, is scraped off by the scraper 24, and is returned to the developer reservoir 19 again. Used for image formation. The toner image thus obtained on the photoconductor 14 is
After being transferred onto paper (not shown) by the transfer corona charger 25, it was thermally fixed by a fixing device (not shown). As a result, a sharp image with no background fog or image unevenness was obtained. On the other hand, the toner remaining on the photoconductor 14 after the transfer was conveyed by the movement of the photoconductor 14 and was collected by the cleaner 26.

In this embodiment, fine grooves are provided on the surface of the electrode roller 21, but the surface of the electrode roller 21 is Ra0.5.
Even if blasting is performed as described above, or if a urethane conductive resin layer in which carbon is kneaded is provided on the surface of the electrode roller 21, the frictional force on the toner on the surface of the electrode roller 21 is significantly improved, and the collected toner is collected. Since the paper is transported without slipping, a sharp image with no background fog or image unevenness was obtained.

[0027]

According to the present invention, it is possible to obtain an excellent electrophotographic apparatus having a simple structure, high image quality, and high speed processing.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an electrophotographic apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining the function and effect of the present invention.

FIG. 3 is a vertical magnetic flux density distribution map on the surface of the electrode roller according to the first embodiment of the present invention.

FIG. 4 is an enlarged view for explaining the magnetic pole arrangement according to the first embodiment of the present invention.

FIG. 5 is a schematic diagram showing a waveform of an AC voltage used in the first, second and third embodiments of the present invention.

FIG. 6 is a configuration diagram of an electrophotographic apparatus according to a second embodiment of the present invention.

FIG. 7 is a vertical magnetic flux density distribution diagram on the surface of the electrode roller according to the second embodiment of the present invention.

FIG. 8 is an enlarged view illustrating a magnetic pole arrangement according to a second embodiment of the present invention.

FIG. 9 is a block diagram of an electrophotographic apparatus according to a third embodiment of the present invention.

FIG. 10 is a sectional view of an electrode roller according to a third embodiment of the present invention.

FIG. 11 is a block diagram of a conventional electrophotographic developing device.

[Explanation of symbols]

 1.14 Photoreceptor 2.15 Magnet 3.16 Corona charger 4.17 Grid electrode 5.18 Laser exposure 6.19 Developer reservoir 7.20 Magnetic developer 8 Damper 9.21 Electrode roller 10.22 Magnet 11. 23 AC high-voltage power supply 12/24 Scraper 13-25 Transfer corona charger 26 Cleaner 27 Magnetic plate

Front page continued (72) Inventor Kazumasa Hayashi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Masahiro Aizawa 1006 Kadoma, Kadoma City Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (8)

[Claims] 1. An electrostatic latent image carrier that contains and moves a fixed magnet, a magnetic developer, and an opening facing the fixed magnet, and a magnetic developer on the surface of the electrostatic latent image carrier. And an electrode roller which is installed at a position having a predetermined gap with the surface of the electrostatic latent image holding member for supplying the developer and whose traveling direction rotates in a direction opposite to the traveling direction of the electrostatic latent image holding member. A means for applying a voltage for removing the toner in the non-image area on the electrostatic latent image carrier to the electrode roller, and a magnetic field generating means for generating a magnetic field in the circumferential direction of the electrode roller at the surface position of the electrode roller. And an electrophotographic apparatus. 2. An electrostatic latent image holder that contains a fixed magnet A and moves, a magnetic developer, a developer reservoir for supplying the magnetic developer to the surface of the electrostatic latent image holder, and the static latent image. An electrode roller which is installed at a position having a predetermined gap from the surface of the electrostatic latent image holder, includes a fixed magnet B, and rotates in a traveling direction opposite to the traveling direction of the electrostatic latent image holder; Means for applying a voltage for removing the toner in the non-image area on the electrostatic latent image carrier to the electrode roller, wherein the fixed magnet B has a magnetic flux density distribution having a plurality of peaks on the surface of the electrode roller. An electrophotographic apparatus, wherein peaks of magnetic flux densities generated and adjacent to each other in the circumferential direction of the electrode roller have mutually opposite polarities. 3. An electrostatic latent image carrier that contains a fixed magnet A and moves, a magnetic developer, a developer reservoir for supplying the magnetic developer to the surface of the electrostatic latent image carrier, and the static developer. It is installed at a position having a predetermined gap from the surface of the electrostatic latent image holder, contains a fixed magnet B and a magnetic body inside, and the traveling direction rotates in the opposite direction to the traveling direction of the electrostatic latent image holder. An electrophotographic apparatus comprising: an electrode roller; and means for applying a voltage for removing toner in a non-image area on the electrostatic latent image holding member to the electrode roller. 4. The fixed magnet B and the magnetic body generate a magnetic flux density distribution having a plurality of peaks at the surface position of the electrode roller, and two magnetic flux density peaks adjacent in the circumferential direction of the electrode roller have opposite polarities. The electrophotographic apparatus according to claim 3, wherein the electrophotographic apparatus is provided. 5. An electrostatic latent image holder that includes a fixed magnet and moves, a magnetic developer, a developer reservoir that supplies the magnetic developer to the surface of the electrostatic latent image holder, and the electrostatic latent image carrier. An electrode roller which is installed at a position having a predetermined gap from the surface of the latent image holding member and whose traveling direction rotates in a direction opposite to the traveling direction of the electrostatic latent image holding member, and on the electrostatic latent image holding member. An electrophotographic apparatus comprising: a unit for applying a voltage for removing toner in a non-image area to the electrode roller; and a unit for improving the frictional force against the toner on the surface of the electrode roller. 6. The electrophotographic apparatus according to claim 5, wherein fine grooves are formed on the surface of the electrode roller. 7. The electrophotographic apparatus according to claim 5, wherein the surface of the electrode roller is a rough surface having Ra of 0.5 μm or more. 8. An electrostatic latent image holding member that moves while containing a fixed magnet, a magnetic developer, a developer reservoir for supplying the magnetic developer to the surface of the electrostatic latent image holding member, and the electrostatic latent image holding member. An electrode roller which is installed at a position having a predetermined gap from the surface of the latent image holding member and whose traveling direction rotates in a direction opposite to the traveling direction of the electrostatic latent image holding member, and on the electrostatic latent image holding member. An electrophotographic apparatus comprising: a means for applying a voltage for removing toner in a non-image area to the electrode roller, wherein a conductive resin layer is provided on a surface of the electrode roller.