JPH05341602A - Method for developing electrophotograph and device therefor - Google Patents

Abstract

PURPOSE:To miniaturize a device and to attain high performance by bringing an electrostatic latent image holding body enclosing a rotary magnet into contact with a magnetic developer, then opposing it to an electrode roller and recovering the magnetic developer. CONSTITUTION:A photosensitive body 6 enclosing the magnet roller 7 is electrostatically charged by a corona charger 8, and the photosensitive body 6 is irradiated with a laser beam 10 to form an electrostatic latent image, then magnetic one-component toner 12 is attached to the surface of the photosensitive body 6 by the magnetic force of the roller 7 in a developer reservoir 11. At this time, the toner 12 is disarranged on the photosensitive body 6 attending on the rotation of the roller 7, and while being electrostatically charged, it is moved attending on the movement of the photosensitive body 6. Then, the photosensitive body 6 is allowed to pass the front of the electrode roller 13, and the toner 12 of a non-image part on the photosensitive body 6 is transferred to the roller 13 side by impressing AC voltage on which DC voltage is superposed on the roller 13 by a high voltage power source 15. The toner 12 attached to the roller 13 is scraped by a scraper 16, and returned in the developer reservoir 11 to be used for next image formation.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventional electrophotographic developing methods include a cascade developing method, a touchdown developing method, a jumping developing method and the like. Among them, the 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 developing method is the first developing method used in a copying machine for electrophotography.

Further, an AC bias is applied to the developing roller 1
U.S. Pat. No. 38 as a method for flying and developing a component toner
There is 66574. In this invention, it is explained that the AC bias applied to the developing roller is used for the purpose of activating the movement of the toner, and the toner reaches the image portion and jumps back 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. 63-42256. This jumping developing method is a developing method in which toner is carried on a toner carrier and is carried to a developing section, where the toner is attached to the image section of the photoconductor by an AC bias. This Japanese public Sho 63-42
The technical idea of the 256 publication is that the toner reciprocates in the image portion and the non-image portion in the above-mentioned US Pat.
It is different from 866574.

[0005]

As is well known in the art, the cascade development method is not good at reproducing solid images. Further, there is a problem that the device becomes large and complicated. Further, US Pat.
The 6574 developing device has a drawback that the device requires high accuracy and is complicated and costly. In the jumping development method, since a photoreceptor is developed by a toner carrier carrying a toner layer, it is essential to form a very uniform thin layer on the toner carrier in order to obtain high image quality. Further, in this method, a so-called sleeve ghost phenomenon occurs in which the history of the previous image remains in the toner thin layer on the toner carrier and an afterimage appears in the image. In addition, the device is complicated and the cost is high.

In view of the above problems, an object of the present invention is to provide an electrophotographic developing method and apparatus having a simple structure and high image quality.

[0007]

In order to solve the above problems, the present invention provides a step of moving an electrostatic latent image holding member containing a rotating magnet, and the electrostatic latent image holding member holds a magnetic developer. Facing the developer reservoir, contacting the electrostatic latent image holding member with the magnetic developer, and facing the electrostatic latent image holding member to an electrode roller provided with a gap to collect the magnetic developer. And an electrophotographic developing method.

Further, according to the present invention, the step of forming and moving an electrostatic latent image on the electrostatic latent image holding member, magnetically attracting and adhering the magnetic developer to the surface of the electrostatic latent image holding member facing the developer reservoir. An electrophotographic developing method comprising: a step of facing the magnetic developer to an electrode roller having a magnet inside; a step of applying an AC voltage to the electrode roller to recover the magnetic developer adhering to the electrostatic latent image holding member. Is.

Furthermore, the present invention provides a step of forming and moving an electrostatic latent image on an electrostatic latent image holder containing a rotating magnet, and a developer reservoir containing a magnetic developer inside the electrostatic latent image holder. And a magnetic developer adhered to the electrostatic latent image holder, a step of regulating the amount of magnetic developer adhered to the electrostatic latent image holder by a developer amount regulating plate, and an electrostatic latent image holder. And a step of collecting the magnetic developer by an electrode roller which is installed through a gap and to which a voltage is applied to obtain an image.

Further, according to the present invention, there is provided an electrostatic latent image holding member which contains a rotating magnet and moves, a developer reservoir, a magnetic developer, and an electrode roller which is installed with a gap between the electrostatic latent image holding member and the electrostatic latent image holding member. And an electrophotographic developing device having.

Further, according to the present invention, the electrostatic latent image holding member which contains a rotating magnet and moves, the developer reservoir, the one-component magnetic developer, and the electrostatic latent image holding member are installed via a gap. An electrophotographic developing device having an electrode roller.

Still further, according to the present invention, an electrostatic latent image holding member which contains a rotating magnet and moves, a developer reservoir, a one-component magnetic developer, and an electrostatic latent image holding member which are installed with a gap therebetween. And an electrode roller having a magnet on its side.

Still further, according to the present invention, an electrostatic latent image holding drum that contains a rotating magnet and moves, a developer reservoir, a one-component magnetic developer, and the electrostatic latent image holding drum via a gap. An electrophotographic developing apparatus having an installed electrode roller, wherein the rotation axis of the electrostatic latent image holding drum is different from the rotation axis of the rotating magnet.

Furthermore, the present invention has an electrostatic latent image holder that contains a rotating magnet and holds and moves an electrostatic latent image, an electrostatic latent image holder that holds a magnetic developer inside, and an opening. Then, a developer reservoir facing each other, a developer amount regulating plate for regulating the amount of the magnetic developer adhered to the electrostatic latent image holding member, and the electrostatic latent image holding member are installed via a gap and a voltage is applied. An electrophotographic developing device having an electrode roller.

[0015]

According to the present invention, an electrostatic latent image holder containing a rotating 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 is carried to the electrode roller portion. 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. That is, the present invention is a cascade development method in which a rotating magnet is installed inside the electrostatic latent image holding member, and an AC voltage is applied to the electrodes. In the present invention, after the toner is attracted to the electrostatic latent image holding member by the magnetic force, the toner moves on the electrostatic latent image holding member by the rotation of the magnet roller, resulting in uniform charging. The electrode roller portion circulates the toner in the developer reservoir and at the same time collects the toner in the non-image portion of the electrostatic latent image.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The technical idea of the present invention will be described with reference to FIG.
Reference numeral 1 is an electrostatic latent image holder on which an electrostatic latent image is formed, 2 is toner, 3 is a developing electrode, 4 is a magnet, and 5 is a power source. In the conventional method, as shown in (b), toner is attached to the image portion of the electrostatic latent image holding member to obtain the toner image of (c). On the other hand, in the present invention, as shown in (d), the magnetic developer is once attached to the entire surface of the electrostatic latent image holding member by magnetic force, and then (e).
As shown in (4), the toner is taken from the non-image portion by electrostatic force or with the help of the magnetic force of 4. That is, the conventional example is a "developing method of adhering toner to an image portion", and the present invention is a "developing method of stripping toner of an unnecessary non-image portion".

Due to such a difference in technical idea, the electrode roller of the present invention and the conventional method, for example, Japanese Patent Publication No. 63-42256.
The following difference in configuration occurs from the developing roller disclosed in Japanese Patent Publication No. (1) It is the electrostatic latent image carrier that carries and carries the developer from the developer reservoir to the developing section. (2) In the conventional developing roller, the surface on which the toner layer is carried always faces the electrostatic latent image holding member. On the other hand, the electrode roller of the present invention always has a bare surface facing the electrostatic latent image carrier.

That is, in the present invention, the electrostatic latent image carrier carries the developer from the developer reservoir to the developing section, and the toner collected by the bare electrode roller is immediately removed from the developing section.

As described above, according to the present invention, due to the difference in the structure in which the toner is collected on the bare surface of the electrode roller, the sleeve ghost phenomenon caused by the uneven thickness of the toner layer on the toner carrier, which has been a big problem in the past, is present. There is a difference in action and effect that does not occur.

Further, according to the present invention, since the magnet inside the electrostatic latent image holder is rotated, this rotational movement can be used to accelerate the transport of the developer on the electrostatic latent image holder.
This is particularly effective when the developer has poor fluidity.
Further, as the magnet rotates, the developer causes a disturbance motion on the electrostatic latent image holding member, so that sufficient triboelectrification is generated, so that a higher quality image can be obtained.

Further, in the present invention, since the moving direction of the electrode roller is opposite to the moving direction of the electrostatic latent image holding member,
The bare electrode roller can precisely remove the toner on the electrostatic latent image carrier. As a result, (1) unevenness in the developing direction did not occur, (2) horizontal line resolution was high, and (3) sufficient image density was obtained.

Further, in the present invention, the developer is in contact with the electrostatic latent image on the surface of the electrostatic latent image holding member for a longer time as compared with the conventional magnetic brush developing method, so that the developing efficiency is extremely high and the high speed adaptability is excellent. It's easy to understand.

As the electrostatic latent image carrier used in the present invention, zinc oxide, selenium, cadmium sulfide, amorphous silicon, or an organic photoconductor using phthalocyanine or an azo pigment can be used. Needless to say, ordinary electrostatic recording paper or the like may be used. The surface of the electrostatic latent image carrier may be roughened by sandblasting or the like to promote the formation of the developer layer.

The magnet inserted inside the electrostatic latent image holder has the number of magnetic poles of the magnet inside the electrostatic latent image holder in order to improve the transportability of the developer and the motility of the toner during development. 4
It is desirable to have a roller shape with more than eight poles, preferably about eight poles. At this time, as shown in FIG. 1, when the shaft center of the magnet roller is located at a position different from the rotation axis of the electrostatic latent image holding member, the developer attracted to the electrostatic latent image holding member by magnetic force is held. As the body moves in the direction of the arrow, the attraction force to the electrostatic latent image holding body gradually weakens, and the toner can be easily collected by the electrode roller portion. The direction of rotation of the magnet roller is preferably the same as that of the electrostatic latent image holding member in order to efficiently charge the toner. On the other hand, in the high-speed image forming process, if the rotation direction of the magnet roller is opposite to that of the electrostatic latent image holding member, the rotation of the magnet roller also assists the toner conveyance, which is effective.

In the present invention, a developer reservoir having an opening on the surface of the electrostatic latent image carrier is used. The developer is configured to come into direct contact with the electrostatic latent image holding member from the developer reservoir, and the developer is magnetically attracted to the electrostatic latent image holding member regardless of whether or not it is charged. The width of the opening of the developer reservoir facing the electrostatic latent image holding member in the moving direction of the electrostatic latent image holding member needs to be 5 mm or more, preferably 10 to 15 mm.

The toner used in the present invention may be a so-called two-component developer toner. This is one in which a coloring pigment such as carbon black or phthalocyanine 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 size of the toner used is 1
5 μm or less is desirable, but if 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.

In the present invention, the magnetic developer may be an insulating one-component toner. If a one-component toner is used, the device configuration can be simplified. The one-component toner used in the present invention is
A magnetite or ferrite powder is dispersed in a binder resin such as styrene resin or acrylic resin together with a charge control agent, 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. The average particle diameter of the toner used is preferably 15 μm or less, but if it is 12 μm or less, a sharper image can be obtained.

In this electrophotographic developing method, the toner is once attached to the entire surface of the electrostatic latent image holding member, and then the toner in the non-image portion is removed by the electrode roller. With this method, it has been found that when the fluidity of the toner is poor, the toner in the non-image area adheres strongly to the electrostatic latent image holder and cannot be removed, resulting in background fog and degrading the image. When silica fine particles are externally added to the surface of the toner, the fluidity of the toner is improved, and the non-electrostatic adhesion force to the electrostatic latent image holding member is reduced,
It had the effect of eliminating the fog. At this time, it was found that the silica particles not only contributed to the improvement of the fluidity but also contributed to the charging of the toner. In this electrophotographic developing method, it is not necessary to provide a charging member for charging the toner in the case of a one-component toner, and if silica particles are added to the toner, when the toner comes in contact with the charged electrostatic latent image holding member, , It was found that it plays a role of moving electric charges from the side of the electrostatic latent image holder to the side of the toner to charge the toner to the same polarity as that of the electrostatic latent image holder. The silica fine particles are also called colloidal silica.

In the present invention, a two-component developer comprising toner and magnetic carrier can be used. The toner used in the present invention is obtained by dispersing a color pigment such as carbon black or phthalocyanine in a binder resin such as an acrylic resin or a polyester resin, pulverizing and classifying. The toner may be a powder obtained by spray drying, or a powder chemically obtained by a pearl polymerization method, an emulsion polymerization method, or the like. Further, the toner particles may be directly mixed with the carrier, or silica particles or fluororesin fine powder may be adhered to the surface of the toner. The average particle size of the toner used is preferably 15 μm or less, but 12 μm
A sharper image can be obtained by the following.

The distance between the electrode roller and the electrostatic latent image carrier is
100 μm to 700 μm when a one-component toner is used
Degree: 400 μm to 2 m when using a two-component developer
Installed about m meters apart.

The material of the electrode roller may be conductive.
When the fluidity of the developer is poor, if the electrode roller is made of a magnetic material, the magnetic lines of force from the magnet roller inside the electrostatic latent image holder reach the electrode roller, and as a result, the developer transportability is improved. Examples of such a material include soft iron, magnetic stainless steel, nickel and the like. The surface of the electrode roller may be a polished one, or may be one having an uneven surface by sandblasting or the like or a groove.

The electrode roller may be a non-magnetic roller having a magnet fixed inside. For example, there is a configuration in which a magnet is inserted into a cylinder made of non-magnetic stainless steel or aluminum.

An alternating voltage is applied to this electrode roller. Of course, a pulse waveform or a triangular wave may be used as long as an alternating electric field is effectively applied to the electrostatic latent image holder.
The frequency of this alternating voltage varies depending on the process speed of image formation, and is in the range of approximately 50 Hz to 10 kHz, preferably 300 to 3000 Hz. The value of the AC voltage is a zero-to-peak value, which is preferably about 0.4 to 3 times the charging potential of the electrostatic latent image carrier, and more preferably 0.5 to 2 times. In the case of reversal development, the value of the DC voltage superposed on the AC voltage is equal to the charging potential of the electrostatic latent image holding member or several tens thereof.
% When set to a low value, a good negative-positive inverted image can be obtained. On the other hand, in the case of normal development, a good positive image can be obtained by setting the value to be equal to or higher than the background potential of the electrostatic latent image carrier by several tens of percent.

When the rotating direction of the electrode roller is opposite to the moving direction of the electrostatic latent image holding member at the developing position,
High image quality can be obtained, and the device configuration can be simplified.

In order to effectively remove the fog on the electrostatic latent image carrier, it is preferable to increase the moving speed of the electrode roller. On the other hand, the slower the moving speed of the electrode roller, the more carefully the toner on the electrostatic latent image carrier can be removed. The speed of the electrode roller is preferably 0.3 to 2.0 times the moving speed of the electrostatic latent image holding member.

The toner attached to the electrode roller is scraped off by a scraper provided in the developer reservoir, and the toner is returned to the developer reservoir again. This scraper is preferably electrically insulated so as not to affect the electrode roller. Therefore, for example, plastic such as polyester film is preferable for this scraper. This scraper can be made of stainless steel or phosphor bronze plate, but at this time, in order to prevent the electrode roller from being electrically affected, insulate it so that it does not come into electrical contact with anything other than the electrode roller. There is a need to.

(Specific Embodiment 1) FIG. 1 shows an embodiment of the electrophotographic developing apparatus of the present invention. In FIG. 1, 6 is an organic photosensitive drum in which metal-free phthalocyanine is dispersed in a polycarbonate binder resin, and 7 is a photosensitive body 6.
With a magnetic roller having a diameter of 10 mm and having a magnetic pole of 8 poles having a rotational axis different from the rotational axis of No.
Rotate at mm / s. 8 is a corona charger for negatively charging the photoconductor 6, 9 is a grid electrode for controlling the charging potential of the photoconductor, 10 is signal light, 11 is a developer reservoir, and 12 is a negatively chargeable magnetic particle having an average particle size of about 10 μm. It is a one-component toner. 13 is an electrode roller made of non-magnetic stainless steel, 14 is a fixed magnet contained in the electrode roller, 15 is an AC high-voltage power supply for applying voltage to the electrode roller, 16 is a scraper made of polyester film for scraping off toner on the electrode roller, Reference numeral 17 denotes a transfer corona charger that transfers the toner image on the photoconductor onto the paper 18. The magnetic flux density on the surface of the photoconductor 6 of the magnet roller 7 is 800 Gs. The diameter of the photoconductor 6 is 30 m
It was rotated at a peripheral speed of 30 mm / s at m. The magnetic flux density on the surface of the electrode roller 13 of the magnet 14 is 800 Gs. The electrode roller 13 was rotated at a peripheral speed of 30 mm / s in the direction of the arrow.

The composition of 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 developing apparatus configured as described above will be described below with reference to FIG. The photoconductor 6 was charged to -500V by a corona charger 8 (applied voltage-4kV, grid 9 voltage -500V). The photoconductor 6 was irradiated with laser light 10 to form an electrostatic latent image. At this time, the exposure potential of the photoconductor 6 was −100V. The magnetic one-component toner 12 was attached to the surface of the photoconductor 6 in the developer reservoir 11 by the magnetic force of the magnet roller 7. At this time, the toner was disturbed on the photoconductor 6 as the magnet roller 7 was rotated, and moved along with the movement of the photoconductor 6 while being charged to approximately −3 μC / g. Next, the photoconductor 6 having the toner layer attached thereto was passed in front of the electrode roller 13. The electrode roller 13 was installed with a distance of 300 μm from the photoconductor 6. A high voltage power supply 15 superimposes a DC voltage of −300 V on the electrode roller 13 with a waveform shown in FIG.
An AC voltage (frequency: 3 kHz) of 0V0-p (peak-to-peak 800V) was applied. The toner layer on the photoconductor 6 moves between the photoconductor 6 and the electrode roller 13, the toner in the non-image area gradually moves to the electrode roller 13 side, and the toner on the photoconductor 6 is negative-positive inverted only in the image area. The statue remains.
The toner adhering to the electrode roller 13 rotating in the direction of the arrow was scraped off by the scraper 16 and returned to the developer reservoir 11 to be used for the next image formation. The toner image thus obtained on the photoconductor 6 was transferred onto the paper 18 by the transfer charger 17 and then thermally fixed by a fixing device (not shown). As a result, a sharp image without scattering of toner was obtained.

(Specific Embodiment 2) FIG. 4 is different from FIG. 1 in the structure of the electrode roller. The structure of the magnetic one-component toner used is the same as that in the first embodiment. Here, the electrode roller 19 did not include a fixed magnet inside, but instead was rotated at a peripheral speed of 90 mm / s, which is higher than that of the first embodiment.

The operation of the electrophotographic developing apparatus configured as described above will be described below with reference to FIG. The photoconductor 6 was charged to -500V by a corona charger 8 (applied voltage-4kV, grid 9 voltage -500V). The photoconductor 6 was irradiated with laser light 10 to form an electrostatic latent image. The magnetic one-component toner 12 was attached to the surface of the photoconductor 6 in the developer reservoir 11 by the magnetic force of the magnet roller 7. At this time, the toner is rotated by the magnet roller 7 and the
It was disturbed above and moved along with the movement of the photoconductor 6 while being charged to approximately −3 μC / g. Next, the photoconductor 6 having the toner layer attached thereto was passed in front of the electrode roller 19. The electrode roller 19 was installed at a distance of 200 μm from the photoconductor 6. The electrode roller 19 is supplied with a high-voltage power source 15 so that
400 of the waveform shown in FIG.
An AC voltage (frequency 3 kHz) of V0-p (peak-to-peak 800 V) was applied. The toner layer on the photoconductor 6 moves between the photoconductor 6 and the electrode roller 19, and the toner in the non-image portion gradually moves to the electrode roller 19 side, and the toner on the photoconductor 6 is negative-positive inverted only in the image portion. The statue remains.
The toner adhering to the electrode roller 19 rotating in the direction of the arrow was scraped off by the scraper 16 and returned to the developer reservoir 11 to be used for the next image formation. The toner image thus obtained on the photoconductor 6 was transferred onto the paper 18 by the transfer charger 17 and then thermally fixed by a fixing device (not shown). As a result, a sharp image without scattering of toner was obtained.

(Specific Embodiment 3) FIG. 5 is a schematic diagram of FIG.
The rotating direction of the magnet roller 7 inside is different. Magnet roller 7
Rotates in the same direction as the direction of travel of the photoconductor, so the toner on the photoconductor tries to move in the direction opposite to the direction of travel of the photoconductor. Therefore, the rotation speed of the magnet roller is set to 80 mm / s, which is slower than that of the first embodiment. The structure of the magnetic one-component toner used is the same as that in the first embodiment.

The operation of the electrophotographic developing apparatus configured as described above will be described below with reference to FIG. The photoconductor 6 was charged to -500V by a corona charger 8 (applied voltage-4kV, grid 9 voltage -500V). The photoconductor 6 was irradiated with laser light 10 to form an electrostatic latent image. The magnetic one-component toner 12 was attached to the surface of the photoconductor 6 in the developer reservoir 11 by the magnetic force of the magnet roller 7. At this time, the toner is rotated by the magnet roller 7 and the
It was disturbed above and moved along with the movement of the photoconductor 6 while being charged to approximately −3 μC / g. Next, the photoconductor 6 having the toner layer attached thereto was passed in front of the electrode roller 13. The electrode roller 13 was installed with a distance of 300 μm from the photoconductor 6. A high voltage power supply 15 is applied to the electrode roller 13 so that -4
750V 0-p (peak-to-peak 1.5kV) AC voltage (frequency 3kHz) superposed with 00V DC voltage
Was applied. The toner layer on the photoconductor 6 moves between the photoconductor 6 and the electrode roller 13, the toner in the non-image area gradually moves to the electrode roller 13 side, and the toner on the photoconductor 6 is negative-positive inverted only in the image area. The statue remains. The toner adhering to the electrode roller 13 rotating in the direction of the arrow was scraped off by the scraper 16 and returned to the developer reservoir 11 to be used for the next image formation. After the toner image thus obtained on the photoconductor 6 is transferred onto the paper 18 by the transfer charger 17,
Heat fixing was performed by a fixing device (not shown). As a result, a sharp image without scattering of toner was obtained.

(Specific Embodiment 4) FIG. 6 shows an embodiment of the electrophotographic developing apparatus of the present invention. In FIG. 6, 6 is an organic photosensitive drum in which metal-free phthalocyanine is dispersed in a polycarbonate binder resin, and 7 is a photosensitive body 6.
The magnet roller is composed of 8 magnetic poles and has a rotation axis different from the rotation axis of (1) and rotates at a peripheral speed of 120 mm / s in the direction of the arrow. 8 is a corona charger for negatively charging the photoconductor 6, 9 is a grid electrode for controlling the charging potential of the photoconductor, 1
0 is a signal light, 11 is a developer reservoir, 12 is an average particle size of about 10
It is a negatively-chargeable magnetic one-component toner of μm. Reference numeral 20 is an electrode roller made of non-magnetic stainless steel, 21 is a fixed magnet contained in the electrode roller, 22 is a direct current high-voltage power supply for applying a voltage to the electrode roller, and 23 is a scraper made of a phosphor bronze plate for scraping the toner on the electrode roller. , 24 and 300μ
m is also a developer amount regulating plate installed at a distance, to which an alternating voltage is applied by a high voltage power source 25 (-3
Peak-to-peak 80 superposed with 00V DC voltage
AC voltage of 0 V, frequency 3 kHz). An insulating base 26 holds the developing material regulating plate 24 and the scraper 23. Reference numeral 17 denotes a transfer corona charger that transfers the toner image on the photoconductor onto the paper 18. The magnetic flux density on the surface of the photoconductor 6 of the magnet roller 7 is 800 Gs. The diameter of the photoconductor 6 is 30 m
It was rotated at a peripheral speed of 30 mm / s at m. The magnetic flux density of the magnet 21 on the surface of the electrode roller 20 is 800 Gs. The electrode roller 20 was rotated at a peripheral speed of 30 mm / s in the direction of the arrow.

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

The operation of the electrophotographic developing apparatus configured as described above will be described below with reference to FIG. The photoconductor 6 is connected to the corona charger 8 (applied voltage-4 kV, grid 9
Of -500V) was charged to -500V. The photoconductor 6 was irradiated with laser light 10 to form an electrostatic latent image.
At this time, the exposure potential of the photoconductor 6 was −100V. The magnetic one-component toner 12 was attached to the surface of the photoconductor 6 in the developer reservoir 11 by the magnetic force of the magnet roller 7. At this time, the toner is rotated by the magnet roller 7 and the
It was disturbed above and moved along with the movement of the photoconductor 6 while being charged to approximately −3 μC / g. Next, the photoconductor 6 having the toner layer attached thereto was passed through the developer amount regulating plate 24 to which an AC voltage was applied. At this time, the toner moved between the photoconductor 6 and the developer amount regulating plate 24, and was uniformly charged to a charge amount of −5 μC / g. Next, this toner layer is applied to the electrode roller 20.
I passed in front of him. The electrode roller 20 is composed of the photoconductors 6 and 3.
It was installed at a distance of 00 μm. A high voltage power supply 25 applied a DC voltage of −400 V to the electrode roller 20.
The toner layer on the photoconductor 6 is gradually transferred to the electrode roller 20 side by the combined action of the electrostatic force and the magnetic force of the electrode roller 20, and the toner on the photoconductor 6 is negative-positive inverted only on the image part. The statue remains. The toner adhering to the electrode roller 20 was scraped off by the scraper 23, returned to the developer reservoir 11 and used for the next image formation. The toner image thus obtained on the photoconductor 6 was transferred onto the paper 18 by the transfer charger 17 and then thermally fixed by a fixing device (not shown). As a result, a sharp image without scattering of toner was obtained.

When the stationary magnet 21 was rotated, a darker image was obtained. Also, a good image can be obtained by using a two-component magnetic developer instead of the one-component developer.

[0049]

According to the present invention, an electrophotographic developing method and apparatus which are small in size, high in image quality and excellent in high-speed adaptability can be obtained. That is, since the toner is collected on the bare surface of the electrode roller, there is an effect that the sleeve ghost development due to the uneven thickness of the toner layer on the toner holder, which has been a problem in the past, does not occur. Further, it is possible to accelerate the transportation of the developer on the electrostatic latent image holding member by using this rotational movement in order to rotate the magnet inside the electrostatic latent image holding member. Further, with the rotation of the magnet, the developer causes a disturbance motion on the electrostatic latent image holding member, so that sufficient triboelectrification is generated and a higher quality image can be obtained. Furthermore, since the moving direction of the electrode roller is opposite to the moving direction of the electrostatic latent image holder, the bare electrode roller can precisely remove the toner on the electrostatic latent image holder. As a result, (1) unevenness in the developing direction does not occur, (2) horizontal line resolution is high, and (3) and sufficient image density can be obtained.

Further, in the present invention, the developer is in contact with the electrostatic latent image on the surface of the electrostatic latent image carrier for a longer time than in the conventional magnetic brush developing method, so that the developing efficiency is extremely high and the high-speed adaptability is excellent. ..

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram explaining a difference in technical idea between a conventional method and the present invention.

FIG. 3 is a schematic diagram showing a waveform of an AC voltage used in the first and second embodiments of the present invention.

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

FIG. 5 is a configuration diagram of an electrophotographic developing device according to a third embodiment of the present invention.

FIG. 6 is a configuration diagram of an electrophotographic developing device according to a fourth embodiment of the present invention.

[Explanation of symbols]

 6 Photoconductor 7 Magnet 8 Corona Charger 9 Grid Electrode 10 Laser Exposure 11 Developer Reservoir 12 Magnetic Developer 13,19,20 Electrode Roller 14,21 Magnet 15 AC High Voltage Power Supply 16,23 Scraper

Claims (13)

[Claims] 1. A step of moving an electrostatic latent image holder containing a rotating magnet, a step of facing the electrostatic latent image holder to a developer reservoir holding a magnetic developer, the electrostatic latent image holder. A step of contacting the magnetic developer with the magnetic developer, and a step of collecting the magnetic developer by facing the electrostatic latent image holding member to an electrode roller provided with a gap therebetween. 2. A step of forming and moving an electrostatic latent image on an electrostatic latent image holding member, a step of magnetically attracting and adhering a magnetic developer to the surface of the electrostatic latent image holding member facing a developer reservoir, An electrophotography comprising: a step of causing the magnetic developer to face an electrode roller having a magnet therein; a step of applying an AC voltage to the electrode roller to recover the magnetic developer adhered to the electrostatic latent image holding member. Development method. 3. 1. A process of forming and moving an electrostatic latent image on an electrostatic latent image holder containing a rotating magnet. 2. a step in which a developer reservoir holding a magnetic developer inside is made to face the electrostatic latent image holder and the magnetic developer is attached to the electrostatic latent image holder. 3. A step of regulating the amount of the magnetic developer adhering to the electrostatic latent image holding member by a developer amount regulating plate, And a step of collecting the magnetic developer with an electrode roller to which a voltage is applied and being provided with the electrostatic latent image holding member so as to obtain an image. 4. An electrostatic latent image holder that contains a rotating magnet and moves, a developer reservoir, a magnetic developer, and an electrode roller installed with the electrostatic latent image holder through a gap. An electrophotographic developing device having. 5. An electrostatic latent image carrier that contains a rotating magnet and moves, a developer reservoir, a one-component magnetic developer, and an electrode roller installed with a gap between the electrostatic latent image carrier and the electrostatic latent image carrier. And an electrophotographic developing device having. 6. An electrostatic latent image holder that contains a rotating magnet and moves, a developer reservoir, a one-component magnetic developer, and a magnet installed inside the electrostatic latent image holder via a gap. An electrophotographic developing device having: an electrode roller having; 7. A structure in which the rotating direction of the rotating magnet is opposite to the traveling direction of the electrostatic latent image holding member.
The described electrophotographic developing device. 8. The rotating magnet is rotated in the same direction as that of the electrostatic latent image holding member.
The described electrophotographic developing device. 9. An electrophotographic developing apparatus according to claim 4, 5 or 6, wherein an alternating voltage is applied to the electrode roller. 10. The structure according to claim 4, wherein the traveling direction of the electrode roller is opposite to the traveling direction of the electrostatic latent image holding member.
Alternatively, the electrophotographic developing device according to the item 6. 11. An electrostatic latent image holding drum which contains a rotating magnet and moves, a developer reservoir, a one-component magnetic developer, and an electrode which is installed through a gap from the electrostatic latent image holding drum. An electrophotographic developing apparatus having a roller, wherein the rotation axis of the electrostatic latent image holding drum is different from the rotation axis of the rotating magnet. 12. 1. An electrostatic latent image holder that contains a rotating magnet and holds and moves an electrostatic latent image. 2. A developer reservoir which holds a magnetic developer therein and faces the electrostatic latent image holding member with an opening. 3. A developer amount control plate that controls the amount of the magnetic developer attached to the electrostatic latent image holding member, An electrophotographic developing device having the electrostatic latent image holding member and an electrode roller which is installed via a gap and to which a voltage is applied. 13. The electrophotographic developing apparatus according to claim 12, wherein an AC voltage is applied to the developer amount regulating plate.