JPH0437780A - Image forming device - Google Patents

Abstract

PURPOSE:To uniformly hold a large amount of sufficiently electrified non- magnetic one component system developer on a developer carrier and to obtain a high-density and high-definition image by providing a charge imparting member composed of a spiral conductive body part on the surface of the developer carrier. CONSTITUTION:The spiral conductive body part is formed on the surface of the charge imparting member 90, many rugged parts are actually formed on the surface of the member 90 by a spiral shape. By this constitution, when the developer carrier 20 comes in contact with the charge imparting member 90, the charge is imported only to a part coming in contact with the conductive body part (spiral-shaped part) of the recessed part of the charge imparting member 90, on the dielectric layer of the developer carrier 20, and not imparted to the surface of the developer carrier corresponding to the recessed part (non- spiral shaped part) of the charge imparting member 90. Therefore, the dielectric layer of the surface of the developer carrier has a state that a large number of the charges are selectively imparted corresponding to the shapes of the rugged parts and toner can be stuck to many layers.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention supplies a non-magnetic one-component developer to which an adjuvant is externally added as necessary to a rotationally driven developer carrier. The developer is carried on the surface of a developer carrier, and the electrostatic latent image formed on the latent image carrier is transferred to a development area where the latent image carrier and the developer carrier face each other. The present invention relates to an image forming apparatus that creates a visible image using the developer carried on a developer carrier.

[Conventional technology]

An electronic copying machine that forms an electrostatic latent image on a latent image carrier and visualizes this using a developer to obtain a recorded image.

2. Description of the Related Art In image forming apparatuses such as printers and facsimiles, dry-type developing devices that use powdered developer are widely used.

As such powder-like developers, two-component developers containing toner and a carrier and one-component developers that do not contain a carrier are known. Two-component developers using the former two-component developer Although this method allows relatively stable and good recorded images to be obtained, carrier deterioration and toner-to-carrier mixing ratio fluctuations are likely to occur, the maintenance and management of the device is complicated, and the overall structure of the device tends to increase in size. It has its drawbacks.

From this point of view, a one-component development system using a one-component developer that does not have the above-mentioned drawbacks is attracting attention. - Component type developers include those consisting only of toner and those consisting of a mixture of toner and an auxiliary agent, to which an auxiliary agent is externally added as required. Furthermore, toners include magnetic toners in which magnetic powder is kneaded into each toner particle itself, and non-magnetic toners that do not contain magnetic material.

Here, since magnetic materials are generally opaque, when a full-color or multi-color image is formed using magnetic toner, the developed visible image becomes unclear, making it impossible to obtain a vivid color image. Therefore, especially for color development, it is desirable to adopt a one-component development method using non-magnetic toner.

By the way, in a developing device that employs a -component development method, a -component developer is carried on a developer carrier and transported, and in a development area where the developer carrier and the latent image carrier face each other, The electrostatic latent image formed on the latent image carrier is made into a visible image using a developer, but in order to form a high-quality visible image with a predetermined density, a large amount of sufficiently charged toner must be applied to the development area. It is necessary to convey the latent image and visualize the latent image using the toner.

When magnetic toner is used, the one-component developer can be carried on the developer carrier by using the magnetic force of a magnet installed inside the developer carrier, so the above requirements can be met relatively easily. Is possible.

However, when a non-magnetic one-component developer is used, it is difficult to satisfy the above requirements because it cannot be supported on a developer carrier by magnetic force. Various countermeasures against this problem have been proposed in the past. For example, in Japanese Patent Application Laid-open No. 61-42672, a layer of dielectric material (#! edge body) is laminated on the surface of the developer carrier (developing roller). On the other hand, a developer supply member made of, for example, a sponge roller is brought into pressure contact, and both are frictionally charged to opposite polarities, and non-magnetic toner charged to the opposite polarity to the dielectric is electrostatically charged to the dielectric. A method has been proposed in which the -component developer is deposited and transported to a development area. However, even with this method, it is not possible to sufficiently increase the strength of the electric field formed near the dielectric surface, so it is difficult to carry a large amount of toner on the surface of the developing roller. Due to the insufficient amount of agent, it is difficult to form a high-density visible image.

Furthermore, a configuration is also known in which an electric field is applied between the developing roller and the developer supply member in a direction in which the non-magnetic toner electrostatically moves toward the developing roller, but even if such a configuration is added, It is difficult to make a sufficient amount of toner adhere to the developing roller.

In addition, as a toner supply member, 102 to 106 Ω・c
m conductive foam (Japanese Unexamined Patent Publication No. 60-229057)
, elastic body with skin layer (Japanese Unexamined Patent Publication No. 60-229060) and fur brush (Japanese Unexamined Patent Publication No. 61-42672)
It has been proposed to use a metal body with an uneven surface (Japanese Patent Laid-Open No. 60-53
No. 976), integrated insulation coated roller (Japanese Patent Application Laid-Open No. 55-4
No. 6768) Medium and low antibody coated roller (Japanese Patent Application Laid-open No. 58-1
3278) and an electrode roller having a #4A edge and a conductive surface (Japanese Patent Application Laid-Open No. 53-36245).

Furthermore, in a developing device using a non-magnetic component developer,
In Japanese Patent Application Laid-Open No. 60-229057, a sponge roller,
JP-A-62-229060 discloses an elastic roller.

JP-A No. 61-52663 discloses that a fur brush or the like is used to charge the toner by frictional charging between the toner and a replenishing member, and further electrostatically transfers the toner to the developing roller by the friction in contact with the developing roller. The latent image on the photoreceptor is developed by controlling the toner layer using a layer thickness regulating member such as a blade. Various materials are used for the developing roller, such as insulating materials, medium resistance materials, and laminated materials.

According to the methods shown in these references, toner adhesion to the developing roller is achieved by frictional electrification between the toner replenishing member and the developing roller, but sufficient electrification cannot be achieved due to friction between the toner-attached member. This results in insufficient toner adhesion. The optimum adhesion amount and charge amount in the non-magnetic component development method will be explained as follows.

For black and white, emphasis is placed on the amount of charge, which is -numerically 10~
It is 20μC/g. If the value is smaller than this value, the image quality will be poor in terms of background stains, sharpness, etc.

Regarding the amount of adhesion, the amount of adhesion on the developing roller is 0.
1-0.3mg/cm2, but 0.4mg/cm2 on the transfer paper
-0.5 mg/am2 is required, and the amount of toner adhesion is covered by increasing the speed of the developing roller to 3 to 4 times the speed of the photoreceptor. However, when the developing roller rotates 3 to 4 times faster, there is a problem that a phenomenon of ``toner from the rear edge'' occurs, that is, when developing a solid area, the density at the rear edge of one image becomes higher. be.

To prevent this phenomenon, the speed of the developing roller should be made close to the speed of the photoreceptor. In other words, it is necessary to increase the amount of toner deposited on the developing roller and reduce the number of rotations.

On the other hand, with color toner, the degree of coloring is lower than that of black toner, and if you try to improve the "from the rear end of the toner", the degree of coloring is even higher than that of black toner, which is 0.8~1,2
An amount of adhesion on the developing roller of mg/cm2 is required. Regarding the amount of charge, in order to obtain a stable image, the amount of charge should be 5 to 20 μC/g (preferably 10 to 15 μC/g).
) is desired.

As a method to solve these problems, the present inventors
First, a one-component developer consisting of a non-magnetic toner to which an adjuvant is externally added as necessary is supplied to a rotationally driven developer carrier, and the developer is carried on the surface of the carrier. In a developing area where the latent image carrier and the developer carrier face each other, the electrostatic latent image formed on the latent image carrier is made visible by the developer carried on the developer carrier. In the developing method for image formation, a large number of minute electric fields are formed near the surface of the developer carrier by selectively holding charges on the surface of the developer carrier, and the charged toner is attracted by the closed electric field, The developer is attached and supported on the surface of the developer carrier,
We proposed an image forming apparatus that visualizes an electrostatic latent image using the developer carried thereon.

In this invention, since a large number of microfields are formed near the surface of the developer carrier, the electric field strength can be significantly increased compared to the conventional method, and a large amount of sufficiently charged non-magnetic material can be generated. This has many advantages, such as being able to carry toner on a developer carrier and transport it to a developing area.

[Problems to be Solved by the Invention] However, even in an image forming apparatus in which a large number of microfields are formed near the surface of the developer carrier as described above, depending on the configuration of the developer carrier, charge imparting member, etc. The problem is that the desired toner adhesion amount and toner charge amount cannot be obtained, and the manufacturing process requires fine processing on the metal roller, and the manufacturing cost increases because more processing steps are required. There is.

Accordingly, an object of the present invention is to provide an image forming apparatus that can obtain a desired toner adhesion amount and toner charge amount, and can be manufactured easily and inexpensively.

[Means to solve the problem]

As a result of intensive studies, the present inventors have discovered that an image forming apparatus that combines a developer carrier with a dielectric layer on its surface and a charge imparting member with a spiral conductor on its surface can achieve the above purpose. The present invention was completed based on this finding.

That is, according to the present invention, on the surface of the developer carrier,
By selectively retaining the charge with the charge imparting member, a large number of minute electric fields are formed near the surface of the developer carrier, and the toner to which an auxiliary agent is externally added as necessary is applied onto the developer carrier. The image forming apparatus supplies a non-magnetic one-component developer, causes the developer to be carried on the surface of a developer carrier by the minute electric field, and visualizes an electrostatic latent image by the carried developer. There is provided an image forming apparatus, characterized in that the developer carrying member is provided with a dielectric layer on the surface thereof, and the charge imparting member is provided with a spiral conductive portion on the surface. be done.

In the image forming apparatus of the present invention, since a large number of minute electric fields are formed near the surface of the developer carrier, the electric field strength can be significantly increased compared to the conventional one. By using a developer carrier having a spiral conductor portion, a large amount of sufficiently charged non-magnetic toner can be carried on the developer carrier and transported to the development area, and the manufacturing cost thereof can be reduced.

Hereinafter, such an image forming apparatus will be explained.

FIG. 1 shows an outline of a typical developing device of the present invention, centering on a developer carrier section and a charge applying section. In Figure 1,
The toner 60 contained in the toner tank 70 is forcibly brought to the toner supply member (sponge roller, fur brush, etc.) 40 by the stirring blade (toner supply auxiliary member) 50, and the toner 60 is supplied to the toner supply member 40. be done.

On the other hand, the developer carrier 20 that has completed development rotates in the direction of the arrow and reaches the contact portion with the charge imparting member 90 .

The charge applying member 90 rotates at the same speed and in the same direction as the developer carrier 20 while being in contact with the developer carrier 20 . In such a contact portion, as will be described later, a large number of charges are selectively applied to the dielectric layer on the surface of the developer carrier by the charge applying member 90, and as shown in FIG. A microfield is formed between adjacent regions with different charged potentials. The developer carrier 20 on which the microfield has been formed continues to rotate further in the direction of the arrow, and reaches a contact portion with the toner powder supply member 40 . Toner supply member 4
The toner 60 charged with zero adheres to the developer carrier 20 due to the microfield effect.

The adhered toner is removed by a toner layer thickness regulating member (elastic blade) 3.
0, the charging is stabilized while the thickness is controlled, and the developing area 80 is reached. In the development area 80, the latent image is developed by contact or non-contact development.

Here, if necessary, bias such as direct current, alternating current, direct current superimposed alternating current, pulse, etc. can be applied to the developer carrier 20 and the toner supply member 40 to control an optimal image.

Next, the mechanism of toner adhesion to this type (electrode type) developer carrier 20 will be explained.

Toner adhesion is as follows. First, the developer carrier 20 that has completed development rotates in the direction of the arrow and comes into contact with the charge imparting member 90 .

While the charge imparting member 90 is in contact with the developer carrier 20,
It rotates in the same direction at the same linear speed as the carrier.

In the present invention, since a spiral conductor portion is formed on the surface of the charge imparting member 90 as shown in an enlarged view in FIG. Irregularities are formed.

In addition, this charge imparting member 90 is powered by a DC power source.
A voltage with a polarity opposite to the charged polarity of the toner is applied. For example, when the toner is triboelectrically charged to a positive polarity, the potential of the charge applying member 90 is maintained at, for example, -250V.

With such a configuration, when the developer carrier 20 and the charge imparting member 90 come into contact, the dielectric layer of the developer carrier 20 has a conductive portion (spiral portion) of the convex portion of the charge imparter 90.
A charge is applied only to the part that is in contact with the

No charge is applied to the surface of the developer carrier corresponding to the concave portion (non-helical portion) of the charge applying member 90. Therefore, a large number of charges are selectively applied to the dielectric layer on the surface of the developer carrier according to the shape of the uneven parts, and countless minute patterns with different charging potentials with a potential difference of, for example, 250 V are formed on the surface. be done.

In this way, a closed electric field is generated between adjacent regions with different charging potentials, and the electric field on the developer carrier 20 at this time becomes a microfield (closed electric field) as shown in FIG. This creates an electric field with a large electric field gradient, making it possible to adhere toner in multiple layers. Further, since the adhered toner is in a closed electric field, it is strongly attracted to the developer carrier 20 side and becomes difficult to separate. The toner layer thickness is further controlled by a toner layer thickness regulating member 30,
The toner in the development area 80 becomes an electric field that easily adheres to the photoreceptor,
Development is performed.

Next, the developer carrier used in the present invention will be explained.

The developer carrier of the present invention has a dielectric layer provided on its surface. In this case, the material used for the dielectric layer can be any insulating material, but organic polymers are usually used. In this case, specific examples of organic polymers include the following.

Vinyl resins such as polyvinyl chloride, polyvinyl butyral, polyvinyl alcohol, polyvinylidene chloride, polyvinyl acetate, polyvinyl formal; polystyrene,
Polystyrene resins such as styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer; polyethylene resins such as polyethylene, ethylene-vinyl acetate copolymer; polymethyl methacrylate, polymethyl methacrylate-styrene copolymer, etc. Acrylic resin; polyacetal, polyamide, cellulose, polycarbonate, phenoxy resin, polyester, fluororesin, polyurethane.

Resin materials such as phenolic resin, 4-urea resin, melamine resin, epoxy resin, unsaturated polyester resin, silicone resin, etc.

Further, the charge imparting member of the present invention is characterized in that, as described above, a spiral conductor portion is formed on the surface thereof.

In order to manufacture such a charge imparting member, a conductive metal material such as a conductive wire is used as a core roll, and the surface thereof is cut into a spiral shape. How to wind it into a spiral coil shape,
It is also possible to adopt a method in which a core metal roll is inserted into a conductive metal material, such as a spring, that has been previously formed into a spiral coil shape. By applying a bias directly to the spiral member, it is possible to use an insulating core metal roll.

Further, a charge imparting member using an elastic body such as rubber for the core roll is preferably used because it can reduce the load due to contact pressure with the developer carrier.

In addition, the conductive material used for the conductor part is 101
Six specific examples of 2Ω・cim or less, preferably 101′Ω・0m or less include AQ, SUS,
In addition to metals such as Fe and Ni, and ceramics,
Examples include organic polymers to which a conductive filler is added. In this case, the organic polymers include the following.

Vinyl resins such as polyvinyl chloride, polyvinyl butyral, polyvinyl alcohol, polyvinylidene chloride, polyvinyl acetate, and polyvinyl formal; polystyrene,
Polystyrene resins such as styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer; polyethylene resins such as polyethylene, ethylene-vinyl acetate copolymer; polymethyl methacrylate, polymethyl methacrylate-styrene copolymer, etc. Acrylic resin; polyacetal, polyamide, cellulose, polycarbonate, phenoxy resin, polyester, fluororesin, polyurethane.

Resin materials such as phenolic resin, urea resin, melamine resin, epoxy resin, unsaturated polyester resin, silicone resin; natural rubber, isoprene rubber.

Butadiene rubber, styrene-butadiene rubber, butyl rubber, ethylene-propylene rubber, chloroprene rubber, chlorinated polyethylene rubber, epichlorohydrin rubber, nitrile rubber, acrylic rubber, urethane rubber, polysulfide rubber,
Rubber materials such as silicone rubber and fluorine rubber.

In addition, conductive fillers include metal powders such as Ni and Cu; carbon blacks such as furnace black, lamp black, thermal black, acetylene black, and channel black; tin oxide, zinc oxide, molybdenum oxide, antimony oxide, and potassium titanate. Conductive oxides such as titanium oxide, electroless plated products plated on mica, etc.; graphite, metal fibers, carbon fibers, etc.

Incidentally, an inorganic filler, a crosslinking agent, a heat stabilizer, a processing aid, etc. can be added to the dielectric layer of the developer carrier used in the present invention for various purposes. Inorganic fillers include diatomaceous earth, quartz powder, iron oxide, zinc oxide, titanium oxide, calcium oxide, magnesium oxide, talc, aluminum silicate, aluminum oxide powder, potassium titanate,
Asbestos, glass, carbon fibers, Teflon,
A powder such as boron nitride is used.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that 5 parts represents parts by weight.

Example: Conductive primer (manufactured by Toray Silicone Co., Ltd. = DY39)
-011) was coated with the following conductive elastic layer forming components on the core metal (6 φ), primary vulcanization = 170°C/10 minutes, 12
0kg/cra'', secondary vulcanization: 200℃/4 hours to press mold the conductive elastic layer with a wall thickness of 6+ms (volume resistivity: 1.5X10SΩ・cll, rubber hardness (JIS
A): 2 g degree) was formed.

[Conductive elastic layer forming component]

Methyl vinyl polysiloxane 100 parts by weight Carbon (Ketchen Black EC) 5 parts by weight Quartz
20 parts by weight of the above mixture
After kneading with this roll, 100 parts by weight of the mixture was mixed with a crosslinking agent (2,4-dimethyl-2,4-di-tertiarybutylpaoxyhexane: manufactured by Toray Silicone Co., Ltd.: RC-4).
) 1.5 parts by weight was added.

Next, after cleaning the surface of the conductive elastic layer with trichlene, a titanate coupling agent (manufactured by Matsumoto Pharmaceutical Co., Ltd.: TA
-25) 1% xylene solution was applied, and after drying for 30 minutes, the following resin layer forming components were spray coated.
The resin layer was cured at 50° C. for 71 hours, and then polished to form a resin layer with a thickness of 50 pIIJ, thereby producing a developer carrier.

[Resin layer forming component]

Coronate El (50% xylene solution) 20 parts by weight Toluene 200 parts by weight Xylene 200 parts by weight Meanwhile, AQ
The surface of the metal roller made of
．． A charge imparting member was produced by providing a spiral portion.

The developer carrier and charge imparting member obtained above were installed in the developing device shown in FIG. 1, and after one rotation of the developer carrier and 10
The amount of toner adhesion and the amount of toner charge on the developer carrier after 0 rotation were measured. The results are shown in Table-1.

Comparative Example The toner adhesion amount and toner charge amount on the developer carrier were measured in the same manner as in Example, except that the charge imparting member was not used. The results are shown in Table-1.

Table 1 From the results in Table 1, it can be seen that the image forming apparatus of the present invention can provide toner with a sufficient amount of charge.

〔Effect of the invention〕

Since the surface of the charge imparting member used in the present invention is composed of a spiral conductor portion, a microfield can be formed on the surface of the developer carrier by a simple method, and its manufacturing cost can be reduced by requiring complicated processing. Since no process is required, it is inexpensive.

Therefore, by selectively retaining charges on the surface of the developer carrier, a large number of minute closed electric fields are formed near the surface of the developer carrier, and on this developer carrier, auxiliary electric fields are applied as needed. A non-magnetic one-component developer made of toner externally added is supplied, the developer is carried on the surface of the developer carrier by the minute closed electric field, and the electrostatic latent image is transformed into a visible image by the carried developer. When the image forming apparatus of the present invention is used in the image forming method of the present invention, a large amount of sufficiently charged non-magnetic one-component developer can be uniformly carried on the developer carrier and transported to the developing area. As a result, a high-density, high-quality image can be obtained, and the cost of forming the image is also low.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an example of an image forming apparatus of the present invention in which a microfield electric field is formed on a developer carrier, centering on a developer carrier section and a charge applying section. Further, FIG. 2 is a schematic cross-sectional view for explaining a state in which a closed electric field is generated by a microfield on a developer carrier in the apparatus shown in FIG. FIG. 3 is a schematic diagram for explaining the structure of the charge imparting member used in the device shown in FIG. 1. 10... Electrostatic latent image carrier, 20... Developer carrier,
30... Toner layer thickness regulating member, 40... Toner supply member, 50... Stirring blade, 60... Toner, 70...
. . . Toner tank, 80 . . . Development area, 90 . . . Charge imparting member. Patent applicant Rico Co., Ltd.

Claims (1)

[Claims] (1) By selectively retaining charges on the surface of the developer carrier by a charge imparting member, a large number of minute closed electric fields are formed near the surface of the developer carrier, and on this developer carrier, A non-magnetic one-component developer made of toner to which an auxiliary agent is externally added as necessary is supplied, the developer is carried on the surface of the developer carrier by the minute closed electric field, and the electrostatic latent is created by the carried developer. An image forming device that visualizes an image,
An image forming apparatus characterized in that the developer carrier is a member having a dielectric layer on its surface, and the charge imparting member is a member having a spiral conductor portion on the surface.