JPH0572890A - Electrophotographic method and device - Google Patents

Abstract

PURPOSE:To provide an electrophotographic method and device for obtaining high image quality, with simple structure by having an electrostatic latent image carrier including a permanent magnet, an electrode installed so as to face the delectrostatic latent image carrier, and a magnetic developer. CONSTITUTION:An organic photosensitive drum 93 having the permanent magnet 94 composed of four magnetic poles, inside, is used, Magnetic one-component toner 99 is transferred, to be magnetically attracted to the electrostatic latent image carrier on which an electrostatic latent image is formed, and carried up to a developer recovery electrode roller 101. Then, an AC bias is applied to the electrode roller 101 from a high voltage power source 103, the toner of the nonimage part of the photosensitive drum 93 is moved to the side of the electrode roller 101, and a toner image inverted in the negative and positive, is left on the nonimage part on the photosensitive drum 93. Thus, a developing unit can be simplified, further, the developing region of the developer coming into contact with a photosensitive body can be widened, and the high image quality is obtained.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a two-component developing method using a magnetic developer has been widely used in an electrophotographic method. Various methods have been proposed up to now as this developing method, but the magnetic brush developing method developed in 1953 has the advantage that the apparatus can be made more compact and the fine line reproducibility is improved compared to the conventional cascade developing method. Because it ’s relatively good,
It has become the mainstream of the electrophotographic development method for copying documents.

An example of the conventional two-component developing method described above will be described below with reference to the drawings. FIG. 1 shows an electrophotographic apparatus using a conventional two-component developing method. In FIG. 1, 1 is a two-component developer in which toner and carrier are mixed. A developing roller 2 includes a magnet roller 3 inside. 4 is an electrophotographic photoreceptor, 5 is a corona charger that charges the electrophotographic photoreceptor, 6 is exposure light that exposes a signal, 7 is a corona charger that transfers a toner image onto paper, and 8 is residual on the photoreceptor This is a cleaning device for cleaning the remaining toner. The operation of the electrophotographic apparatus configured as described above will be described below. First, the photoconductor 4 is charged by the charger 5. After exposure with signal light 6,
An electrostatic latent image is formed and developed by the two-component magnetic brush developer 1 carried on the developing roller 2. Thus photoconductor 4
The toner image obtained above is transferred onto paper using the transfer charger 7. The toner remaining on the photoconductor is cleaned by the cleaning device 8 and used again in the next image forming step.

Other conventional electrophotographic developing methods include a cascade developing method, a touchdown developing method and a jumping developing method.

Among them, a cascade developing method shown in US Pat. No. 3,105,770 is known as a developing method in which a developer is directly sprinkled on the photoreceptor. The cascade development method
This is the first developing method used in electrophotographic copying machines.

A touch-down developing method disclosed in US Pat. No. 3,866,574 is known as a method for flying and developing one-component toner. An AC bias is applied to the developing roller. In the present invention, it is described that the AC bias applied to the developing roller activates the movement of the toner, and the toner reaches the flying portion in the image portion and returns to the developing roller midway in the non-image portion.

Further, as an improved technique for applying the AC bias, there is a jumping developing method disclosed in Japanese Patent Publication No. 58-32375. The jumping developing method is a developing method in which a toner layer is carried on a toner carrier and is carried to a developing unit, and an AC bias is applied to the toner carrier to attach the toner to the image area of the photoconductor. This Japanese Patent Publication No. 58-32375 differs from the above-mentioned US Pat. No. 3,866,574 in the technical idea in that the toner reciprocally moves electrostatically in the image portion and the non-image portion.

A technique similar to this Japanese Patent Publication No. 58-32375 is disclosed in Japanese Examined Patent Publication No. 3-30136. this is,
The charged toner is once electrostatically attached to the entire surface of the photoconductor from the toner carrier, and then an AC voltage is applied to a separately provided non-contact electrode roller to collect unnecessary toner.
This patent differs from the above-mentioned Japanese Patent Publication No. 58-32375 in that there is a step of electrostatically transferring the initially charged toner from the toner carrier to the photoreceptor.

[0009]

However, the magnetic brush developing method has a problem that the structure of the developing device is large and the apparatus becomes large and complicated. Further, there is a problem that the image quality is poor because the contact time between the photosensitive member and the developer is short.

Further, the cascade developing method is not good at reproducing solid images. Further, there is a problem that the structure is large and the device becomes large and complicated.

Further, the developing device of US Pat. No. 3,866,574 has a drawback that the device is required to have high accuracy and is complicated and costly.

Further, the jumping developing method has a structure in which only the image portion of the photoconductor is developed by the toner carrier carrying the toner layer, so that the history of the previous image remains in the toner layer on the toner carrier and the developed image is obtained. The so-called sleeve ghost phenomenon, in which an afterimage appears, was a drawback. In addition, the device is complicated and the cost is high.

In the last Japanese Patent Publication No. 3-30136, a sleeve ghost does not appear because an electrode roller is separately provided, but it has a drawback that the device is complicated and the cost is high because it has two rollers.

An object of the present invention is to obtain an electrophotographic method and apparatus having a simple structure and high image quality.

[0015]

In order to solve the above problems, an electrophotographic method of the present invention is directed to an electrostatic latent image holder containing a fixed magnet, and an electrostatic latent image holder opposed to the electrostatic latent image holder. And a magnetic developer, and after forming an electrostatic latent image on the electrostatic latent image holding member, magnetically attach the magnetic developer to the surface of the electrostatic latent image holding member, The configuration is such that the unnecessary developer other than the image area is removed by the electrodes.

Further, the electrophotographic apparatus of the present invention has an electrostatic latent image holder containing a fixed magnet, a developer hopper, a magnetic developer, a developer amount control plate, and a developer recovery electrode roller. In an electrophotographic apparatus, after an electrostatic latent image is formed on an electrostatic latent image holder, magnetic developer is magnetically attracted to the surface of the electrostatic latent image holder located inside the developer hopper to electrostatically latent image. After the developer is attached to the surface of the image holding member, the electrostatic latent image holding member is moved, and after passing through the developer amount regulating plate, it is opposed to the developer collecting electrode roller, and the image portion of the electrostatic latent image holding member In the electrophotographic apparatus, the toner image is left on the toner and the toner in the non-image portion is collected by the developer collecting electrode roller.

Further, according to the present invention, an electrostatic latent image carrier containing a fixed magnet, a developer hopper, a developer collecting electrode roller, a developer amount regulating plate, and a magnetic developer to which silica particles are externally added. An electrophotographic method using a developing device having a magnetic latent image on the surface of the electrostatic latent image holding member located in the developer hopper after forming an electrostatic latent image on the electrostatic latent image holding member. Magnetically attract the developer to the surface of the electrostatic latent image carrier, move the electrostatic latent image carrier, pass through the developer amount control plate, and form the developer layer on the electrostatic latent image carrier. After the formation, the toner image is left on the image portion of the electrostatic latent image holding member while facing the developer collecting electrode roller provided with a gap wider than the thickness of the developer layer, and the toner in the non-image portion is removed. This is an electrophotographic method of collecting with a developer collecting electrode roller.

Further, according to the present invention, an electrostatic latent image holder containing a fixed magnet, a developer hopper, a developer collecting electrode roller, a developer amount regulating plate, and a magnetic developer to which silica particles are externally added. An electrophotographic method using a developing device having a magnetic latent image on the surface of the electrostatic latent image holding member located in the developer hopper after forming an electrostatic latent image on the electrostatic latent image holding member. Magnetically attract the developer to the surface of the electrostatic latent image carrier, move the electrostatic latent image carrier, pass through the developer amount control plate, and form the developer layer on the electrostatic latent image carrier. After the formation, the toner image is left on the image portion of the electrostatic latent image holding member while facing the developer collecting electrode roller provided with a gap narrower than the thickness of the developer layer, and the toner in the non-image portion is removed. This is an electrophotographic method of collecting with a developer collecting electrode roller.

Further, the electrophotographic apparatus of the present invention includes an electrostatic latent image carrier containing a fixed magnet, a developer hopper, a magnetic developer containing toner, a developer amount regulating plate, and a magnet. An electrophotographic apparatus having a rotating developer collecting electrode roller and a high-voltage power supply for applying an alternating voltage to the developer collecting roller, wherein after forming an electrostatic latent image on an electrostatic latent image holder,
The magnetic developer is magnetically attracted to the surface of the electrostatic latent image holder located in the developer hopper to carry the magnetic developer on the surface of the electrostatic latent image holder, and the magnetic developer is passed through the developer amount regulating plate. After the layer thickness is regulated, the electrostatic latent image holding member is rotationally moved to convey the magnetic developer and face the developer collecting electrode roller, and the magnetic developing agent is moved to the electrostatic latent image holding member and the developer collecting electrode roller. The electrophotographic apparatus is configured to collect the magnetic developer on the developer collecting electrode roller after applying an alternating voltage from the high voltage power source during the period.

[0020]

According to the present invention, a photosensitive member having a fixed magnet inside is used, and toner is sprinkled and magnetically adhered to an electrostatic latent image carrier on which an electrostatic latent image is formed, and then carried and conveyed to an electrode roller section.
An AC bias is applied to the electrode roller to remove unnecessary toner on the non-image portion of the photoconductor by electrostatic force. That is, the present invention is a conventional electrophotographic developing method, in which a magnet for adsorbing a developer is installed inside the photoconductor, and a voltage is applied to an electrode provided outside the photoconductor, thereby reducing the size.
It is a high-performance product. As a result, the developing device can be simplified, and the developing area of the developer that comes into contact with the photoconductor can be increased, so that high image quality can be obtained. In the present invention, when the toner is first sprinkled on the photoconductor, the development is almost completed, and the electrode roller unit circulates the toner in the developing hopper and at the same time, removes the toner in the non-image part of the photoconductor electrostatic latent image. Collected.

The difference in structure between the electrode roller of the present invention and the developing roller used in the conventional developing method will be described. (1) In the present invention, it is the photoreceptor containing the magnet that carries and carries the toner from the toner hopper to the developing section, and the concept of the conventional electrostatic latent image carrier and the toner carrier is embodied in the same configuration. It is a thing. Since the configuration is based on this technical idea, there is a difference in that the image forming method is a method of removing unnecessary toner in the non-image area, rather than attaching and developing the toner to the image area. (2) The electrode roller of the present invention has a structure in which the bare surface always faces the photoconductor, and the toner collected by the electrode roller is immediately removed from the developing section by the rotation of the roller. In the conventional method of developing an image portion with a thin toner layer formed on the developing roller, the uniformity of the thin toner layer on the developing roller appears in the image as it is, so high accuracy is required for forming the toner layer. To be done. However, when the toner layer having an excessive thickness is first formed on the photoconductor as in the present invention, and the toner is later collected by the bare collecting roller, most of the non-uniform portion of the toner layer is collected by the collecting roller. Then, the toner is moved to the side and flattened on the photosensitive member so that a uniform toner image can be left.

According to the present invention, the magnet is provided in the inner space of the photoconductor, and the conveying movement of the developer can be used as the moving force of the photoconductor. Since the toner is collected on the bare surface, sleeve ghost does not occur.

[0023]

EXAMPLE The present invention uses an electrophotographic photosensitive drum containing a magnet. This magnet is fixed and does not rotate, only the photoconductor rotates. At this time, if the magnet and the photoconductor are supported coaxially, there is an advantage that the mechanism for driving the photoconductor can be simplified and the magnetic pole position can be easily adjusted. As the photoconductor used in the present invention, an organic photoconductor using zinc oxide, selenium, cadmium sulfide, phthalocyanine or an azo pigment can be used.

The toner used in the present invention is a so-called 2 toner.
A toner for the component developer can be used. this is,
Coloring pigments such as carbon black and phthalocyanine,
It is dispersed in a binder resin such as styrene resin or acrylic resin, pulverized and classified. The toner may be a powder obtained by spray drying or a powder chemically obtained by a pearl polymerization method or the like. In this case, if silica fine particles are adhered to the surface of the toner, the fluidity of the toner is improved, and as a result, the fog is eliminated. The toner particles may be mixed as they are with the carrier, or depending on the use conditions, fine particles of fluororesin, fine plastic powder, zinc stearate or the like may be adhered to the surface of the toner. The average particle diameter of the toner used is preferably 15 μm or less, but when it is 12 μm or less, a sharper image can be obtained.

The carrier used in the two-component developer of the present invention is a magnetic substance such as iron powder or ferrite powder, or those whose surface is coated with a resin, and fine powder such as ferrite powder or magnetite in an amount of about 30 to 80%. A magnetic powder or the like is used, which is dispersed and mixed in a ratio of styrene resin, epoxy resin, styrene acrylic resin, and pulverized and classified. The average particle size of the carrier is preferably 300 μm or less, but particularly 150
If it is less than μm, the toner can be uniformly charged.

An insulating one-component toner can be used as the magnetic developer of the present invention. If a one-component toner is used, the device configuration can be simplified. The one-component toner used in the present invention is obtained by dispersing powder of magnetite or ferrite together with a charge control agent in a binder resin such as styrene resin or acrylic resin, pulverized and classified. The toner may be a powder obtained by spray drying or a powder chemically obtained by a pearl polymerization method or the like. In this developing method, the toner is once attached to the entire surface of the photoconductor, and the toner in the non-image area is removed later by the developer collecting electrode roller. However, in this method, if the toner has poor fluidity,
The toner in the non-image area adheres strongly to the photoconductor and cannot be removed, resulting in background fog and degrading the image. When silica fine particles are externally added to the surface of this toner, the fluidity of the toner is improved, the non-electrostatic adhesion to the photoconductor is reduced, and the effect of eliminating fog is obtained. At this time, the silica particles not only contribute to the improvement of the fluidity but also contribute to the charging of the toner. In this developing method, in the case of a one-component toner, it is not necessary to particularly provide a charging member for charging the toner, and if silica particles are added to the toner, when the toner comes in contact with the charged photoreceptor, the charge is transferred from the photoreceptor side to the toner side. It was found that the toner was charged to the same polarity as the photoconductor. The silica fine particles are also called colloidal silica.

In the present invention, a developer hopper having an opening on the surface of the photoreceptor is used. The developer is configured to directly contact the photoconductor from the developer hopper.

When the photoreceptor having such a structure passes through the developer hopper, the developer adheres to the photoreceptor due to the magnetic force,
It moves with the movement of the photoconductor. At this time, when the developer is a one-component toner, the developer remains attached to the photoconductor due to electrostatic attraction and so-called van der Waals force even if the developer leaves the magnetic field.

The amount of the developer attached to the surface of the photoconductor is
It is regulated by the developer amount regulating plate. For this developer amount regulating plate, an elastic body such as a rubber plate can be used. At this time, if a urethane or silicone rubber plate is softly brought into direct contact with the surface of the photoconductor, a uniform thin layer of developer is formed on the surface of the photoconductor. In addition, soft iron, nickel, magnetic stainless steel (SUS43
A magnetic substance such as 0) may be used. At this time, if the developer amount regulating plate is installed at a position facing the one magnetic pole contained in the photoconductor with a distance, the magnetic flux connecting the two will partially obstruct the outflow of the developer, resulting in uniform distribution. It becomes possible to form a different developer layer on the photoreceptor. Further, when the developer amount regulating plate is used as a conductor and a DC voltage is applied, the developer layer can be formed more easily. For example, when a DC voltage that is approximately the same as or higher than the surface potential of the photoconductor is applied, the developer is pushed from the developer amount regulating plate toward the photoconductor, and a uniform dense developer thin layer is formed. It is suitable that the distance between the developer amount regulating plate of the magnetic material and the surface of the photoconductor is 100 μm to 4 mm. The thin developer layer thus formed has a thickness of 10
From 0 μm to about 4 mm, particularly in the case of a one-component toner, a sharp line image was obtained when the developer layer thickness was set to about 50 μm. As a power source applied to the developer amount regulating plate, a dedicated high-voltage power source may be separately provided, but when the charger for charging the photoconductor is a scorotron having a grid electrode, the grid electrode and the developer amount regulating plate are electrically connected. The purpose can be easily achieved by connecting to.

The developer collecting electrode roller and the photoconductor are 100 μm.
It is installed at a distance of 4 mm from m. This distance
If it is set wider than the thickness of the developer layer formed on the photoconductor, a sharp line image can be obtained. On the other hand, in order to obtain a higher solid image density, the distance between the photoconductor and the developer collecting electrode roller may be set smaller than the thickness of the developer layer. That is, at this time, the tip of the developer layer on the photoconductor contacts the developer collecting electrode roller. The material of the developer collecting roller may be any material as long as it is conductive, and examples thereof include stainless steel and aluminum. The surface of the developer electrode roller may be polished or may be provided with unevenness by sandblasting or the like. Further, a conductive resin having graphite or the like dispersed in enamel may be coated on the conductive support. Such selection is determined in consideration of the fluidity of the developer used. An alternating voltage is applied to the developer collecting electrode roller. The frequency of this alternating voltage varies depending on the image forming process speed, but is in the range of approximately 50 Hz to 5000 Hz, preferably 30 Hz.
A range of 0 to 3000 Hz is good. The value of the AC voltage is a zero-to-peak value, which is preferably about 0.5 to 3 times the charging potential of the photoconductor, and further 0.5 to 1.5.
A double value is preferred. The value of the DC voltage that is superimposed on the AC voltage is equal to the charging potential of the photoconductor or several ten
% When set to a low value, a good negative-positive inverted image can be obtained. Needless to say, in the case of regular development, it is sufficient to apply a voltage substantially equal to the exposure potential of the photoconductor using a toner of opposite polarity. When such a voltage is applied to the developer collecting electrode roller, the developer adhering to the surface of the photoconductor moves between the photoconductor and the developer collecting electrode roller, and gradually the developer in the non-image area of the photoconductor is removed. It moves to the developer collecting electrode roller side, and the developer image remains only in the image portion. The outer peripheral moving direction of the developer collecting electrode roller is preferably the same as the outer peripheral moving direction of the photoconductor, and when the moving speeds thereof are substantially the same, the edge effect peculiar to electrophotography does not appear, and uniform solid part development is achieved. Was obtained. However, conversely, when the edge is emphasized in order to improve the character reproduction, the reverse rotation may be performed.
In order to efficiently collect the developer on the photoconductor, it is effective to put a magnet inside the developer collecting electrode roller. The developer adhering to the developer collecting electrode roller may be scraped off by a scraper provided in the developer hopper, and the developer may be returned to the developer hopper again, or may be discharged to the outside of the developing device as it is. good.

The developer attached to the developer collecting electrode roller is scraped off by a scraper provided in the developer hopper. The scraper is preferably electrically insulated so as not to affect the developer collecting electrode roller. Therefore, for example, plastic such as polyester film is preferable for this scraper.
This scraper may be made of stainless steel, phosphor bronze plate, or the like, but at that time, in order to prevent the developer collecting electrode roller from being electrically affected, an electric circuit other than the developer collecting roller is used. Insulation must be done to prevent contact with It is preferable that the scraper and the above-described developer amount regulating plate are integrally configured in terms of the device configuration. With such a configuration, the configuration of the device is simplified and the size can be reduced. (Embodiment 1) The electrophotographic developing device of the present invention is described below.
A description will be given with reference to the drawings.

FIG. 2 shows an embodiment of the electrophotographic apparatus of the present invention. In FIG. 2, 9 is an organic photoconductor drum in which phthalocyanine is dispersed in a binder resin, 10 is a magnet having two magnetic poles fixed coaxially with the photoconductor 9, and 11
Is a corona charger for negatively charging the photoconductor, 12 is signal light, 13 is a developer hopper, 14 is an iron powder carrier having a particle diameter of 150 μm, 15 is negatively charged toner, 16
Is a developer in which a carrier 14 and a toner 15 are mixed, 17
Is a transfer corona charger that transfers the toner on the photoconductor to paper. The magnetic flux density at the surface position of the photoconductor 9 is 800 Gs. The diameter of the photoconductor 9 was 31 mm, and it was rotated at a peripheral speed of 30 mm / s.

The operation of the electrophotographic apparatus configured as described above will be described below with reference to FIG. Photoconductor 9
Was charged to -700V with a corona charger 11 (applied voltage-4kV). The photoconductor 9 was irradiated with laser light 12 to form an electrostatic latent image. The developer hopper 1 is placed on the photoconductor 9.
Developer 3 in which carrier 14 and toner 15 are mixed in
When 6 was attached by magnetic force and passed through, a negative-positive inverted toner image was developed on the line portion and the solid edge portion of the electrostatic latent image. The toner image thus obtained on the photoconductor 9 is
After being transferred onto paper (not shown) by the transfer charger 17, it was thermally fixed by a fixing device (not shown). On the other hand, after transfer, the photoreceptor 9 was charged again by the corona charger 11 and used in the next image forming step. As a result, a sharp line image without toner scattering was obtained. (Second Embodiment) A second embodiment of the present invention will be described below with reference to FIG.

In FIG. 3, 18 is an organic photosensitive drum in which phthalocyanine is dispersed in a binder resin, 19 is a magnet consisting of two magnetic poles fixed coaxially with the photosensitive body 20, 20
Is a corona charger for negatively charging the photoconductor, 21 is a signal light by laser exposure, 22 is a developer hopper, 23 is an iron powder carrier having a particle diameter of 150 μm, 24 is a toner charged negatively, and 25 is a carrier 23 and toner. A developer mixed with 24, 26 is an electrode plate provided inside the developer hopper, and 27 is a high-voltage power supply for applying a voltage to the electrode plate 26. On the photoconductor 18 and in the developer hopper 22, a developer 25 obtained by mixing the carrier 23 and the toner 24.
Was attached by magnetic force. Further, in the developer 25 inside the developer hopper 22, an electrode plate 26 having a width of 5 mm is provided in the photosensitive member 18.
It was installed at a distance of 2 mm from the surface of. A voltage of -600 V was applied to the electrode plate 26 by the high voltage power supply 27. Two
Reference numeral 8 is a transfer corona charger that transfers the toner on the photoconductor to the paper. The magnetic flux density at the surface of the photoconductor 18 is 800G
s. The diameter of the photoconductor 18 is 31 mm, and the peripheral speed is 30 mm /
Rotated with s.

The operation of the electrophotographic apparatus configured as described above will be described below with reference to FIG. Photoconductor 1
8 is -700V with corona charger 20 (applied voltage -4kV)
Charged to. The photoconductor 18 was irradiated with laser light 21 to form an electrostatic latent image. When this photoconductor was passed through the developer 25 described above, a toner image which was negative-positive inverted to the electrostatic latent image was developed. The toner image thus obtained on the photoconductor 18 was transferred onto a sheet of paper (not shown) by the transfer charger 28, and then thermally fixed by a fixing device (not shown). On the other hand, after the transfer, the photoconductor 18 was charged again by the corona charger 20 and used in the next image forming step. As a result, a sharp line image with no toner scattering around the image line was obtained, and as an effect of using the counter electrode plate, a solid image with a density of 1.5 was obtained.

In the second embodiment, the voltage of the power supply is DC voltage, but AC voltage may be applied. (Embodiment 3) Next, a third embodiment of the present invention will be described in detail with reference to FIG.

As a one-component toner, a styrene acrylic resin was mixed with an oxycarboxylic acid metal complex (3%) as a charge control agent and magnetite (40%) as a magnetic material, and the mixture was pulverized and classified to have an average particle diameter of 12 μm (density 1. The toner of 3) was used. This one-component toner was negatively charged when it came into contact with the developer hopper and the photoconductor. In FIG. 4, 29 is an organic photosensitive drum in which phthalocyanine is dispersed in a binder resin, 30 is a magnet having two magnetic poles fixed coaxially with the photosensitive body 29, 31 is a corona charger for negatively charging the photosensitive body, 32 is a signal light by laser exposure, 33 is a developer hopper, 34 is the above-mentioned negatively charged one-component toner, 35 is a counter electrode roller installed at a distance of 300 μm from the photoconductor, and 36 is an electrode roller 35. A high-voltage power source for applying a voltage, 37 is a developer amount regulating plate made of soft iron, and is installed at a distance of 240 μm from the surface of the photosensitive member 29 at one end and in contact with an electrode roller at the other end. This has the purpose of controlling the amount of developer adhering to the photoconductor 29 and scraping the developer adhering to the electrode roller 35. Reference numeral 38 is a transfer corona charger for transferring the toner on the photoconductor to the paper. The magnetic flux density at the surface position of the photoconductor 29 is 800 Gs. The diameter of the photoconductor 29 is 31 mm
Then, it was rotated at a peripheral speed of 30 mm / s.

The photoconductor 29 was charged to -700V by a corona charger 31 (applied voltage-4kV). The photoconductor 29 was irradiated with a laser beam 32 to form an electrostatic latent image. The one-component toner 34 in the developer hopper 33 is applied to the photoreceptor 29.
And was passed through the developer amount regulating plate, a toner layer having a thickness of about 30 μm was attached to the entire surface of the photoconductor. To the electrode roller 35, a high voltage power supply 36 is applied to generate a DC voltage of -650V,
A voltage in which an AC bias having a voltage of 1 kVo-p and a frequency of 1 kHz was superposed was applied, and the photoconductor 29 was passed in front of the electrode roller 35. The toner is the photoconductor 29 and the electrode roller 35.
As a result, toner remains only on the latent image portion on the photoconductor 29, and other toner is transferred to the developing roller 35 side. The toner image thus obtained on the photoconductor 29 is
After being transferred onto paper (not shown) by the transfer charger 38, it was thermally fixed by a fixing device (not shown). On the other hand, after transfer, the photoconductor 29 was charged again by the corona charger 31 and used in the next image forming step. As a result, the obtained image was a sharp line image with no toner scattering around the image line and a solid image with a density of 1.5.

Here, by using the one-component toner, it is possible to obtain a highly reliable and compact developing device with no developer life. By applying an AC voltage to the electrode roller, an image with less background fog was obtained. (Embodiment 4) FIG. 5 shows one embodiment of the electrophotographic apparatus of the present invention. In FIG. 5, 39 is an organic photosensitive drum in which phthalocyanine is dispersed in a binder resin, 40 is a magnet composed of two magnetic poles fixed coaxially with the photosensitive body 4,
1 is a corona charger for negatively charging the photoconductor, 42 is a grid electrode for controlling the charging potential of the photoconductor, 43 is signal light, 44 is a developer hopper, 45 is an average particle diameter of about 12 μm
Negatively charged magnetic one-component toner, 46 is a developer amount control plate made of soft iron, 47 is a developer collecting electrode roller made of aluminum, 48 is an AC high voltage power source for applying a voltage to the developer collecting electrode roller, and 49 is developing A scraper made of polyester film that scrapes off the toner on the agent recovery electrode roller.
Reference numeral 0 is a transfer corona charger that transfers the toner image on the photoconductor to paper. The magnetic flux density on the surface of the photoconductor 39 is 800 Gs. The photoconductor 39 has a diameter of 31 mm and is rotated at a peripheral speed of 30 mm / s.

The photosensitive member 39 was set to -500 by the corona charger 11 (applied voltage-4 kV, voltage of grid 42-500 V).
It was charged to V. The photoconductor 39 was irradiated with the laser beam 43 to form an electrostatic latent image. In the developer hopper 44, the magnetic one-component toner 45 is magnetically adhered onto the surface of the photoconductor 39, and further passed through the developer amount regulating plate 46 to which a voltage of −500 V is applied. Thickness about 5
A toner layer of 0 μm was formed. At this time, the toner was charged to approximately -3 μC / g. Next, the photoconductor 39 having the toner layer attached thereto was passed in front of the developer collecting electrode roller 47. A high voltage power source 48 is provided to the developer collecting electrode roller 47.
Allows 700V0-p with a DC voltage of -450V superimposed
AC voltage (frequency 1 kHz) was applied. The toner layer on the photoconductor 39 moves between the photoconductor 39 and the developer collecting electrode roller 47, and the toner in the non-image area gradually moves to the developer collecting electrode roller 47 side, and only the image area is formed on the photoconductor 39. A negative-positive inverted toner image remained on the sheet. The toner adhering to the developer collecting electrode roller 47 was scraped off by the scraper 49, returned to the inside of the developer hopper 44 and used for the next image formation. The toner image thus obtained on the photoconductor 39 was transferred onto paper (not shown) by the transfer charger 50 and then thermally fixed by a fixing device (not shown). On the other hand, after the transfer, the photoconductor 39 was charged again by the corona charger 41 and used in the next image forming step. As a result, a sharp image without scattering of toner was obtained. (Embodiment 5) FIG. 6 shows one embodiment of the electrophotographic apparatus in the embodiment of the present invention. The configuration of FIG. 6 is the same as that of FIG. 5 except that the configuration of the developer amount regulating plate is different. The developer amount regulating plate 51 is a polyester support 52.
The elastic blade 53 made of urethane and having a thickness of 1 mm is bonded. Developer amount control plate 5 by this elastic blade
1, the thickness of the toner layer deposited on the photoconductor is 30
It was lightly pressed onto the photoreceptor so that the thickness became μm.

When this apparatus was used to form an image under the same conditions as in Example 4, a beautiful image with a solid density of 1.5 was obtained without scattering of toner around the image line. (Embodiment 6) The configuration of FIG. 7 differs from the configuration of FIG. 5 in that the magnetic developer is a two-component developer in which toner and carrier are mixed. Other configurations are the same as those in FIG. In the developer hopper 54, a two-component developer 57 in which an iron powder carrier 55 having a particle size of 100 μm and a surface coated with a silicone resin and a toner 56 colored with carbon black are mixed is put,
The magnetic force was applied to the surface of the photoconductor 58. This developer 5
When the photoconductor 58 carrying the electrostatic latent image is passed through 7,
The component developer 57 was attracted to the magnet 59 and did not move, but only the toner 56 moved together with the photoconductor 58, and a toner layer of about 30 μm was obtained on the photoconductor 58. After that, a toner image was obtained on the photoconductor 58 through the visualization process using the developer collecting electrode roller 59 in the same manner as described in Concrete Example 4. The obtained toner image was transferred onto paper (not shown) by the transfer charger 60, and then heat-fixed by a fixing device (not shown). On the other hand, after the transfer, the corona charger 61 is again used.
Then, the photoconductor 58 was charged and used in the next image forming step. As a result, a sharp image without scattering of toner was obtained. (Embodiment 7) In FIG. 8, 62 is an organic photosensitive drum in which phthalocyanine is dispersed in a polyester binder resin, 63 is a magnet consisting of two magnetic poles fixed coaxially with the photosensitive member 62, and 64 is a negative photosensitive member. , 65 is a grid electrode for controlling the charging potential of the photoconductor, 66 is a signal light, 67 is a developer hopper, 68 is a negative charging magnetic one-component toner having an average particle size of about 10 μm, 6
Reference numeral 9 denotes a developer amount control plate made of nickel, which is a magnetic material, and is electrically connected to the grid electrode 65 of the corona charger 64. Reference numeral 70 denotes a developer collecting electrode roller made of aluminum, 7
Reference numeral 1 is an AC high-voltage power supply that applies a voltage to the developer collecting electrode roller, 72 is a scraper made of polyester film that scrapes off the developer on the developer collecting electrode roller 70, and 73 is a toner image on the photoconductor, which is transferred onto paper. It is a transfer corona charger. The magnetic flux density on the surface of the photoconductor 62 is 800 Gs.
The diameter of the photoconductor 62 was 30 mm, and the photoconductor 62 was rotated at a peripheral speed of 30 mm / s. The composition of the magnetic one-component toner used is 70% polyester resin, 25% ferrite, 3 carbon black.
%, Oxycarboxylic acid metal complex 2%, and 0.4% of colloidal silica was externally added and used (all are% by weight). The photoconductor 62 is replaced by a corona charger 64 (applied voltage-4
It was charged to -500V with kV and the voltage of the grid 65 of -500V). The photoconductor 62 was irradiated with laser light 66 to form an electrostatic latent image. At this time, the exposure potential of the photoconductor is -10.
It was 0V. Magnetic one-component toner 68 is adhered to the surface of the photoconductor 62 in the developer hopper 67 by magnetic force, and a distance of 240 μm is established between the photoconductor 62 and the developer amount regulating plate 69 to which a voltage of −500 V is applied. It was Then, a toner layer having a thickness of about 80 μm was formed on the photoconductor 69. At this time, the toner was charged to approximately -3 μC / g. Next, the photoconductor 62 having the toner layer attached thereto was passed in front of the developer collecting electrode roller 70. The developer collecting electrode roller 70 was installed with a distance of 300 μm from the photoconductor 62. High voltage power supply 7 is applied to the developer collecting electrode roller 70.
1, 400V0-p (peak-to-peak 800) with a DC voltage of -300V superimposed on the waveform shown in FIG.
V) AC voltage (frequency 300 Hz) was applied. The toner layer on the photoconductor 62 moves between the photoconductor 62 and the developer collecting electrode roller 70, and the toner in the non-image area gradually moves to the developer collecting electrode roller 70 side, and only the image area is formed on the photoconductor 62. A negative-positive inverted toner image remained on the sheet. The toner adhering to the developer collecting electrode roller 70 was scraped off by the scraper 72, returned to the inside of the developer hopper 67, and used for the next image formation. The toner image thus obtained on the photoconductor 62 was transferred onto a sheet of paper (not shown) by the transfer charger 73, and then thermally fixed by a fixing device (not shown). On the other hand, after the transfer, the photoconductor 62 was charged again by the corona charger 64 and used in the next image forming step. As a result, a sharp image without scattering of toner was obtained. (Embodiment 8) The constitution of FIG. 10 differs from the constitution of FIG. 8 in that the magnetic developer is a two-component developer in which toner and carrier are mixed. Other configurations are the same as those in FIG. The toner used is styrene acrylic resin with 5% carbon black,
An oxycarboxylic acid metal complex of 2% was used, and 0.1% of colloidal silica was externally added and used (all are% by weight). Inside the developer hopper, a ferrite powder carrier 74 having a particle size of 100 μm, the surface of which is coated with a silicone resin.
A two-component developer 76, which is a mixture of a toner 75 and a toner 75, was put in and attached to the surface of the photoconductor 77 by magnetic force. When this developer 76 is passed through the photoconductor 77 on which the electrostatic latent image is formed, the two-component developer 76 is attracted to the magnet and does not move, but the toner 75
Only the toner moved with the photoconductor 77, and after passing through the developer amount regulating plate 78, a toner layer of about 30 μm was obtained on the photoconductor 77. After that, through the visualization process by the same developer collecting electrode roller 79 as described in the concrete example 7, the photoconductor 7
A toner image was obtained on 7. The obtained toner image was transferred onto paper (not shown) by a transfer charger 80 and then heat-fixed by a fixing device (not shown). On the other hand, after the transfer, the photoconductor 77 was charged again by the corona charger 81 and used in the next image forming step. As a result, a sharp image without scattering of toner was obtained. (Embodiment 9) In FIG. 11, 81 is an organic photosensitive drum in which phthalocyanine is dispersed in a polyester binder resin, 82 is a magnet having four magnetic poles fixed coaxially with the photosensitive body 81, and 83 is a negative surface of the photosensitive body. , 84 is a grid electrode for controlling the charging potential of the photoconductor, 85 is a signal light, 86 is a developer hopper, 87 is a negative charging magnetic one-component toner having an average particle size of about 10 μm, 8
8 is a non-magnetic stainless steel developer amount control plate, 89 is a developer recovery electrode roller made of aluminum,
Reference numeral 90 is an AC high-voltage power supply that applies a voltage to the developer collecting electrode roller, 91 is a scraper made of a polyester film that scrapes off the toner on the developer collecting electrode roller 89, and 92 is a transfer that transfers the toner image on the photoconductor to paper. It is a corona charger. The magnetic flux density on the surface of the photoconductor 81 is 1000 Gs. The diameter of the photoconductor 81 was 30 mm, and the photoconductor 81 was rotated at a peripheral speed of 30 mm / s. The composition of the magnetic one-component toner used was 61% of polyester resin, 37% of magnetite, and 2% of metal complex of oxycarboxylic acid, and 1.0% of colloidal silica was externally added and used (all are% by weight).

The photosensitive member 81 is set to -500 by a corona charger 83 (applied voltage -4 kV, grid 84 voltage -500 V).
It was charged to V. The photoconductor 81 was irradiated with laser light 85 to form an electrostatic latent image. At this time, the exposure potential of the photoconductor 81 was −100V. A magnetic one-component toner 87 is attached to the surface of the photoconductor 81 by a magnetic force in a developer hopper 86, and a voltage of -500 V is applied to the photoconductor 8.
When passing through a developer amount regulating plate 88 which is installed with a distance of 150 μm from the first surface, a thickness of about 200 is obtained on the photoconductor 81.
A μm toner layer was formed. At this time, the toner was charged to approximately −5 μC / g. Next, the photoconductor 81 having the toner layer attached thereto was passed in front of the developer collecting electrode roller 89. At this time, the developer collecting electrode roller 89 and the photoconductor 8
The distance from 1 was set to 150 μm. A 450V 0-p (peak-to-peak 90) superposed with a DC voltage of -400V is applied to the developer collecting electrode roller 89 by a high voltage power source 90.
An AC voltage (frequency: 600 Hz) of 0 V was applied. The toner layer on the photoconductor 81 moves between the photoconductor 81 and the developer collecting electrode roller 89, and the toner in the non-image portion gradually moves to the developer collecting electrode roller 89 side, so that only the image portion on the photoconductor 81 exists. The toner image that was negative-positive inverted remained. The toner adhering to the developer collecting electrode roller 89 was scraped off by the scraper 91, returned to the inside of the developer hopper 86, and used for the next image formation. The toner image thus obtained on the photoconductor 81 was transferred onto a sheet of paper (not shown) by the transfer charger 92, and then thermally fixed by a fixing device (not shown). On the other hand, after the transfer, the photoconductor 81 was charged again by the corona charger 83 and used in the next image forming step. As a result, a dark image having a reflection density of 1.7 in the solid image portion was obtained. (Embodiment 10) In FIG. 12, 93 is an organic photosensitive drum in which phthalocyanine is dispersed in a binder resin, 94 is a magnet consisting of four magnetic poles fixed coaxially with the photosensitive body 93,
95 is a corona charger for negatively charging the photoconductor, 96
Is a grid electrode for controlling the charging potential of the photoconductor, 97 is a signal light, 98 is a developer hopper, and 99 is an average particle size of about 10 μm.
m is a negatively chargeable magnetic one-component toner, 100 is a developer amount regulating plate made of stainless steel, 101 is a developer collecting electrode roller made of aluminum, and 102 is a developer collecting electrode roller 1.
A magnet composed of four magnetic poles fixed coaxially with 01, 10
3 is an AC high-voltage power supply for applying a voltage to the developer collecting electrode roller, 104 is a scraper made of polyester film for scraping off the developer on the developer collecting electrode roller 101, 10
Reference numeral 5 denotes a transfer corona charger that transfers the toner image on the photoconductor to paper. The magnetic flux density on the surface of the photoconductor 93 and the surface of the developer recovery electrode roller 101 is 800 Gs. Photoconductor 9
The diameter of 3 was 30 mm, and it was rotated at a peripheral speed of 30 mm / s.

The photosensitive member 93 is set to -500 by a corona charger 95 (applied voltage -4 kV, grid 96 voltage -500 V).
It was charged to V. The photosensitive member 93 was irradiated with laser light 97 to form an electrostatic latent image. In the developer hopper 98, the magnetic one-component toner 99 is magnetically attached onto the surface of the photoconductor 93, and further passed through the developer amount regulating plate 100 to which a voltage of −500 V is applied. A toner layer having a thickness of about 150 μm was formed. At this time, the toner was charged to approximately -3 μC / g. Next, the photoconductor 93 having the toner layer attached thereto was passed in front of the developer collecting electrode roller 101. At this time, the distance between the photoconductor 93 and the developer recovery electrode roller 101 was set to 200 μm. The developer collecting electrode roller 101 is set to -45 by the high voltage power source 103.
An AC voltage of 700 V 0-p (frequency 1 kHz) on which a DC voltage of 0 V was superimposed was applied. The toner layer on the photoconductor 93 moves between the photoconductor 93 and the developer collecting electrode roller 101,
The toner in the non-image area gradually becomes the developer collecting electrode roller 101.
Then, the negative-positive inverted toner image remains only on the image portion on the photoconductor 93. The toner adhering to the developer collecting electrode roller 101 is attached to the developer collecting electrode roller 101 by an internal magnet 102 and is conveyed to the scraper 1
It was scraped off by 04 and returned again to the developer hopper 98 for use in the next image formation. The toner image thus obtained on the photoconductor 93 was transferred onto a sheet of paper (not shown) by the transfer charger 105, and then thermally fixed by a fixing device (not shown). On the other hand, after the transfer, the corona charger 95 again causes the photoreceptor 93 to
Was charged and used in the next image forming step. As a result, a sharp image without scattering of toner was obtained. (Embodiment 11) In FIG. 13, 106 is an organic photosensitive drum in which an azo pigment is dispersed in a binder resin, 107 is a magnet having four magnetic poles fixed coaxially with the photosensitive body 106,
108 is a corona charger for negatively charging the photoconductor, 1
Reference numeral 09 is a grid electrode for controlling the charging potential of the photoconductor, 11
0 is a signal light, 111 is a developer hopper, 112 is a two-component developer in which an iron powder carrier 113 having a particle size of 100 μm whose surface is coated with a silicone resin and a toner 114 colored with carbon black are mixed, and 115 is a photoconductor 106. A developer amount control plate made of stainless steel, which is installed with a distance of 1 mm, 1
Reference numeral 16 is a developer collecting electrode roller made of aluminum which is installed at a distance of 1 mm from the photoconductor 106, 117 is a magnet having three magnetic poles fixed coaxially with the developer collecting electrode roller 116, and 118 is a developer. An AC high voltage power supply for applying a voltage to the collecting electrode roller, 119 is a scraper made of a polyester film for scraping off the developer on the developer collecting electrode roller, 120 is a drain for discharging the used developer,
Reference numeral 121 denotes a transfer corona charger that transfers the toner image on the photoconductor onto paper. The magnetic flux density on the surface of the photoconductor 106 and the surface of the developer collecting electrode roller 116 is 800 Gs. The diameter of the photoconductor 106 was 30 mm, and it was rotated at a peripheral speed of 30 mm / s.

The photoconductor 106 is charged with a corona charger 108 (applied voltage -4 kV, grid 109 voltage -500 V).
It was charged to 500V. Laser light 1 is applied to the photoconductor 106.
10 was irradiated to form an electrostatic latent image. Developer hopper 11
In FIG. 1, a two-component magnetic developer 112 having a toner concentration of 10% is magnetically attached onto the surface of the photoconductor 106 and passed through a developer amount regulating plate 115, and a thickness of about 1. A 2 mm developer layer was formed. Next, the photoconductor 106 to which the developer layer is attached is attached to the developer collecting electrode roller 11
Passed in front of 6. A high-voltage power supply 118 applied an alternating voltage of 700 V 0-p (frequency 1 kHz) on which a DC voltage of −450 V was superimposed, to the developer collecting electrode roller 116.
The developer layer on the photoconductor 106 moves between the photoconductor 106 and the developer collecting electrode roller 116, and the negative-positive inverted toner image remains only on the image portion on the photoconductor 106, and the other developer is the developer. It moved to the collection electrode roller 116 side. The developer adhering to the developer collecting electrode roller 116 was adhered to the developer collecting electrode roller 116 by an internal magnet 117, conveyed, scraped by a scraper 119, and discharged to a drain 120. The toner image thus obtained on the photoconductor 106 is transferred onto a sheet (not shown) of the transfer charger 12.
After transfer by No. 1, it was heat-fixed by a fixing device (not shown). As a result, a sharp image without scattering of toner was obtained.

[0045]

As described above, the present invention has an electrostatic latent image holder containing a fixed magnet, an electrode provided opposite to the electrostatic latent image holder, and a magnetic developer. After the electrostatic latent image is formed on the latent image holding member, the magnetic developer is magnetically attached to the surface of the electrostatic latent image holding member, and then the magnetic developer in the non-image area is removed by the electrode. With such a configuration, it is possible to obtain an electrophotographic method and apparatus having a simple configuration and high image quality.

[Brief description of drawings]

FIG. 1 is a schematic view of a conventional electrophotographic developing device.

FIG. 2 is a configuration diagram of an electrophotographic developing apparatus according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of an electrophotographic developing device according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram of an electrophotographic developing device according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram of an electrophotographic apparatus according to a fourth embodiment of the present invention.

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

FIG. 7 is a configuration diagram of an electrophotographic apparatus according to a sixth embodiment of the present invention.

FIG. 8 is a configuration diagram of an electrophotographic apparatus according to a seventh embodiment of the present invention.

FIG. 9 is a schematic diagram showing a waveform of an AC voltage used in a seventh embodiment of the present invention.

FIG. 10 is a block diagram of an electrophotographic apparatus according to an eighth embodiment of the present invention.

FIG. 11 is a configuration diagram of an electrophotographic apparatus according to a ninth embodiment of the present invention.

FIG. 12 is a configuration diagram of an electrophotographic apparatus according to a tenth embodiment of the present invention.

FIG. 13 is a configuration diagram of an electrophotographic apparatus according to an eleventh embodiment of the present invention.

[Explanation of symbols]

 9 Photoconductor 10 Magnet 11 Corona Charger 12 Laser Exposure 13 Developer Hopper 14 Carrier 15 Toner 16 Developer 17 Transfer Charger 18 Photoconductor Drum 19 Magnet

Front page continuation (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G03G 15/06 101 7818-2H 15/08 112 9222-2H 15/09 Z 8305-2H 101 8305-2H 21 / 00 113 6605-2H 118 6605-2H (31) Priority claim number Japanese Patent Application No. 3-130928 (32) Priority date Hei 3 (1991) June 3 (33) Priority claim country Japan (JP)

Claims (30)

[Claims] 1. An electrostatic latent image holder containing a fixed magnet,
After forming an electrostatic latent image on the electrostatic latent image holding member, which has an electrode disposed facing the electrostatic latent image holding member, and a magnetic developer, on the surface of the electrostatic latent image holding member. An electrophotographic method comprising magnetically adhering the magnetic developer and removing unnecessary developer other than the image area by the electrode. 2. The electrophotographic method according to claim 1, wherein the magnetic developer is a two-component developer including a magnetic carrier and a toner. 3. The electrophotographic method according to claim 1, wherein the magnetic developer is a magnetic one-component toner. 4. An electrostatic latent image holder containing a fixed magnet,
An electrophotographic apparatus comprising an electrode provided facing the electrostatic latent image holding member, and a magnetic developer. 5. The electrophotographic apparatus according to claim 4, wherein a fixed magnet inside the electrostatic latent image holding member and the electrostatic latent image holding member are supported coaxially. 6. The electrophotographic apparatus according to claim 4, wherein an AC voltage is applied to the electrodes. 7. An electrostatic latent image holder containing a fixed magnet,
A developer hopper, a magnetic developer, a developer amount regulating plate,
An electrophotographic apparatus having a developer collecting electrode roller, wherein after the electrostatic latent image is formed on the electrostatic latent image holding member, the electrostatic latent image holding member is positioned on the surface of the electrostatic latent image holding member. The magnetic developer is magnetically attracted to adhere the developer to the surface of the electrostatic latent image holder, the electrostatic latent image holder is moved, and the developer is passed through the developer amount regulating plate, and then the development is performed. An electrophotographic apparatus having a structure in which a toner image is left on an image portion of the electrostatic latent image holding member and a toner in a non-image portion is collected by the developer collecting electrode roller so as to face the developer collecting electrode roller. 8. The electrophotographic apparatus according to claim 7, wherein the magnetic developer is a one-component toner. 9. The electrophotographic apparatus according to claim 7, wherein the magnetic developer is a mixture of an insulating toner and a magnetic carrier. 10. The electrophotographic apparatus according to claim 7, wherein the developer amount regulating plate is an elastic body. 11. The electrophotographic apparatus according to claim 7, wherein the developer amount regulating plate is a magnetic material. 12. The electrophotographic apparatus according to claim 7, wherein the developer amount regulating plate is installed at a position facing a magnetic pole of a fixed magnet included in the electrostatic latent image holding member. 13. The electrophotographic apparatus according to claim 7, wherein the developer amount regulating plate is a conductor. 14. The electrophotographic apparatus according to claim 13, wherein a DC voltage is applied to the developer amount regulating plate. 15. The electrophotographic apparatus according to claim 14, wherein the DC voltage is substantially the same as the surface potential of the electrostatic latent image holding member. 16. The charging device is a scorotron having a grid electrode, and the grid electrode and the developer amount regulating plate are electrically connected so as to have the same potential. Electrophotographic device. 17. The electrophotographic apparatus according to claim 7, wherein an outer peripheral moving direction of the developer collecting electrode roller is the same as an outer peripheral moving direction of the electrostatic latent image holding member, and a moving speed thereof is substantially the same. 18. A magnetic developer collected by the developer collecting electrode roller is brought into contact with a scraper in contact with the developer collecting electrode roller.
The electrophotographic apparatus according to claim 7, wherein the electrophotographic apparatus is configured to be returned into the developer hopper. 19. The electrophotographic apparatus according to claim 18, wherein the scraper is electrically insulated from the developer collecting electrode roller. 20. The electrophotographic apparatus according to claim 18, wherein the scraper and the developer amount regulating plate are integrally configured. 21. An electrostatic latent image carrier containing a fixed magnet, a developer hopper, a developer collecting electrode roller, a developer amount regulating plate, and a magnetic developer to which silica particles are externally added. In the electrophotographic method, after the electrostatic latent image is formed on the electrostatic latent image holding member, the magnetic developer is magnetically applied to the surface of the electrostatic latent image holding member located in the developer hopper. A developer is adhered to the surface of the electrostatic latent image holding member by suction, the electrostatic latent image holding member is moved, the developer amount regulating plate is passed, and a developer layer is formed on the electrostatic latent image holding member. After the formation of the developer layer, the developer collecting electrode roller provided with a gap wider than the thickness of the developer layer is opposed to leave a developer image on the image portion of the electrostatic latent image holding member. An electrophotographic method in which the developer in the image area is collected by the developer collecting electrode roller. 22. The electrophotographic method according to claim 21, wherein the charging polarity of the toner is the same as the charging polarity of the electrostatic latent image holding member. 23. The electrophotographic apparatus according to claim 21, wherein the magnetic developer is a one-component toner. 24. The electrophotographic apparatus according to claim 21, wherein the magnetic developer is a mixture of an insulating toner and a magnetic carrier. 25. An electrostatic latent image holder containing a fixed magnet, a developer hopper, a developer collecting electrode roller, a developer amount regulating plate, and a magnetic developer to which silica particles are externally added. In the electrophotographic method, after the electrostatic latent image is formed on the electrostatic latent image holding member, the magnetic developer is magnetically applied to the surface of the electrostatic latent image holding member located in the developer hopper. A developer is adhered to the surface of the electrostatic latent image holding member by suction, the electrostatic latent image holding member is moved, the developer amount regulating plate is passed, and a developer layer is formed on the electrostatic latent image holding member. After the formation of the developer layer, it is opposed to the developer collecting electrode roller provided with a gap narrower than the thickness of the developer layer, leaving a developer image in the image portion of the electrostatic latent image holding member, An electrophotographic method in which the developer in the image area is collected by the developer collecting electrode roller. 26. The electrophotographic method according to claim 25, wherein the charging polarity of the developer is the same as the charging polarity of the electrostatic latent image holding member. 27. The electrophotographic method according to claim 25, wherein the magnetic developer is a one-component toner. 28. An electrostatic latent image holding member containing a fixed magnet, a developer hopper, a magnetic developer containing toner, a developer amount regulating plate, and a developer collecting electrode roller which contains a fixed magnet and rotates. And a high-voltage power supply for applying an AC voltage to the developer collecting roller, wherein the electrophotographic device is located in the developer hopper after forming an electrostatic latent image on the electrostatic latent image holder. The magnetic developer is magnetically attracted to the surface of the electrostatic latent image holding member to carry the magnetic developer on the surface of the electrostatic latent image holding member, and the magnetic developer is passed through the developer amount regulating plate. After the layer thickness is regulated, the electrostatic latent image holding member is moved to convey the magnetic developer, and the magnetic developer is opposed to the developer collecting electrode roller, and the magnetic developer is developed with the electrostatic latent image holding member. AC voltage from the high voltage power supply was applied between the agent recovery electrode rollers After that, the electrophotographic apparatus configured to collect the magnetic developer on the developer collecting electrode roller. 29. The electrophotographic apparatus according to claim 28, wherein the outer peripheral moving direction of the developer collecting electrode roller is the same as the outer peripheral moving direction of the electrostatic latent image holding member. 30. The electrophotographic apparatus according to claim 28, wherein the outer peripheral moving direction of the developer collecting electrode roller is the same as the outer peripheral moving direction of the electrostatic latent image holding member, and the moving speed thereof is substantially the same.