JP2881215B2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrostatic latent image carrier carrying an electrostatic latent image and a developer carrying body carrying a developer in a developing section. Related Art Related to a developing device that visualizes the electrostatic latent image with the developer in a developing section [Prior Art] An electrostatic latent image is formed on a latent image carrier, and this is visualized with a developer and recorded. 2. Description of the Related Art In an image forming apparatus such as an electronic copying machine, a printer or a facsimile for obtaining an image, a dry developing apparatus using a powdery developer is widely used.

As such a powdery developer, a two-component developer having a toner and a carrier and a one-component developer without a carrier are known, and two-component development using the former two-component developer is known. In the method, although a relatively stable and good recorded image is obtained, deterioration of the carrier and fluctuation of the mixing ratio of the toner and the carrier are apt to occur, maintenance of the apparatus is complicated, and the structure of the entire apparatus is easily enlarged. Has disadvantages.

From such a viewpoint, a one-component developing method using a one-component developer which does not have the above-mentioned disadvantages has attracted attention. The one-component developer includes a toner composed of only a toner and a mixture of a toner and an auxiliary agent to which an auxiliary agent is added as necessary. As the toner, there are a magnetic toner in which magnetic powder is kneaded into each toner particle itself, and a non-magnetic toner containing no magnetic material.

Here, since the magnetic material is generally opaque, if a color image including full-color or multi-color is formed with a magnetic toner, the developed visible image becomes unclear and a vivid color image cannot be obtained. Therefore, it is desirable to adopt a one-component developing method using a non-magnetic toner especially for color development.

By the way, in a developing device employing a one-component developing method, a one-component developer is carried on a developer carrier and transported. In a developing region where the developer carrier and the latent image carrier are opposed to each other, The electrostatic latent image formed on the latent image carrier is visualized with a developer, but in order to form a high quality visible image of a predetermined density, a large amount of sufficiently charged toner must be applied to the developing area. The latent image needs to be conveyed and visualized with the toner.

In the case where a magnetic toner is used, the one-component developer can be carried on the developer using the magnetic force of a magnet provided in the developer carrier. Is possible.

However, when a non-magnetic one-component developer is used,
Since this cannot be carried on the developer carrying member by magnetic force, it is difficult to satisfy the above requirements. Various countermeasures against this have been proposed in the past. For example, JP-A-61-42672 discloses a developer carrier (developing roller).
A layer of a dielectric (insulator) is formed on the surface of the substrate, and a developer supply member such as a sponge roller is pressed against the layer to frictionally charge the two with different polarities. A method has been proposed in which a non-magnetic toner charged to a polarity is electrostatically attached to a dielectric and such a one-component developer is transported to a development area. However, even with this method, the strength of the electric field formed in the vicinity of the dielectric surface cannot be sufficiently increased, so that it is difficult to carry a large amount of toner on the surface of the developing roller, and the developing roller can be transported to the developing area. Insufficient amounts of the agent make it difficult to form a high-density visible image.

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

Examples of the toner supply member include a conductive foam of 10 ² to 10 ⁶ Ω · cm (JP-A-60-229057), an elastic body with a skin layer (JP-A-60-229060), and a fur brush. (Japanese Patent Application Laid-Open No. 61-42672) and the like, and as a developing roller, a metal body having an uneven surface (Japanese Patent Application Laid-Open No. 60-53976), an insulating coated roller body ( Japanese Unexamined Patent Publication No. Sho 55-46768 discloses a medium resistance coated roller (Japanese Unexamined Patent Publication No. 58-13278) and an electrode roller having an insulator and a conductive surface (Japanese Unexamined Patent Publication No. Sho 53-36245). .

In a developing apparatus using a non-magnetic one-component developer, a sponge roller is disclosed in JP-A-60-229057, an elastic roller is disclosed in JP-A-62-222960, and a developing roller is disclosed in JP-A-61-52663.
In the publication, a fur brush or the like is used to apply electric charge to the toner by frictional charging between the toner and the replenishing member, and further, by friction in contact with the developing roller, electrostatically attaches the toner to the developing roller. The latent image on the photosensitive member is developed by controlling the toner layer using a layer thickness regulating member such as a blade. As the material of the developing roller, various materials such as an insulating material, a medium-resistance material, and a laminated material are used.

According to the methods described in these references, toner is adhered to the developing roller by frictional charging between the toner replenishing member and the developing roller. And toner adhesion is insufficient. The following describes the optimal amount of adhesion and the amount of charge in the non-magnetic one-component developing system.

For black and white, the charge amount is important, and it is generally 10 to
20 μC / g. If the value is smaller than this value, the image quality such as background smear and sharpness is inferior. Regarding the coating weight, although the adhesion amount on the developing roller is 0.1 to 2.0 mg / cm ^2, the transfer paper is required 0.4~0.5mg / cm ^2, the speed of the developing roller of the photosensitive body speed 3 to 4 times, the amount of adhered toner is covered. However,
For the rotation of the developing roller 3 to 4 times, "from the rear end of the toner"
That is, when the solid portion is developed, there is a problem that the development that the density at the rear end of the image becomes high occurs. In order to prevent this phenomenon, the speed of the developing roller should be close to the speed of the photoconductor. That is, the number of rotations must be reduced by increasing the amount of adhesion on the developing roller.

On the other hand, the color characteristics of the color toner are smaller than that of the black toner, and the color characteristics are 0.8 to 1.2 mg / cm ² , which is higher than that of the black toner.
Is required on the developing roller. Also, regarding the charge amount, in order to obtain a stable image, 5 to 20 μm
A value of C / g (preferably 10-15 μC / g) is desired.

As a method of solving these problems, the present inventors have previously described "supplying a developer to which a supplement is externally added to a rotationally driven developer carrier, if necessary, The electrostatic latent image formed on the latent image carrier is carried on the developer carrier in a developing region where the latent image carrier and the developer carrier are opposed to each other. In the developing method of forming a visible image using the developer, a plurality of minute closed electric fields are formed near the surface of the developer carrier by selectively holding electric charges on the surface of the developer carrier. An image forming method of sucking charged toner by an electric field, adhering and carrying a developer on the surface of a developer carrying member, and visualizing an electrostatic latent image with the carried developer was proposed.

According to such a method, a large number of minute closed electric fields (microfields) are formed in the vicinity of the surface of the developer carrying member, so that the electric field intensity can be significantly increased as compared with the related art.
It has many advantages such that a large amount of charged developer can be carried on the developer carrier and transported to the development area.

[Problems to be solved by the invention]

However, the developer carrier used in the image forming method in which a large number of microfields are formed near the surface of the developer carrier as described above requires many steps such as fine processing of a metal roller in manufacturing the developer carrier. There is a disadvantage that the cost is high as a result.

Accordingly, an object of the present invention is to use a developer carrier that can secure a sufficient amount of toner adhesion and toner charge in the above-described image forming method, and that can be obtained with a simple manufacturing method and at low cost. An object of the present invention is to provide a developing device.

[Means for solving the problem]

The present inventors have conducted intensive studies, and as a result, have found that a developer carrier in which a conductive material containing insulating particles is formed as a surface layer is suitable for the above object, and have completed the present invention. Was.

That is, according to the present invention, an electrostatic latent image carrier carrying an electrostatic latent image and a developer carrier carrying a developer are opposed to each other in a developing unit, and the electrostatic latent image is In a developing device for visualizing an image with a developer, the developer carrier has a surface layer in which insulating fine particles are dispersed in a conductive material on a conductive substrate, and the insulating fine particles are charged. Forming a minute closed electric field in the vicinity of the surface of the developer carrying member by applying a developer, and supplying a charged developer to the surface of the developer carrying member in which the minute closed electric field is formed in the vicinity of the surface. There is provided a developing device characterized in that the developer is carried by a closed electric field.

In the developing device of the present invention, since a large number of minute closed electric fields are formed in the vicinity of the surface of the developer carrier, the intensity of the electric field can be remarkably increased as compared with the related art, and the conductive substrate is used as the developer carrier. Since a surface layer made of a conductive material in which insulating particles are dispersed is used, a stable toner adhesion amount and toner charge amount can be obtained, and the carrier can be easily manufactured, so that the cost is low. Is possible.

 Hereinafter, such a developing device will be described.

FIG. 1 shows an outline of a typical developing device of the present invention, focusing on a developer carrier. In FIG. 1, toner 60 contained in a toner tank 70 is forcibly brought to a toner supply member (sponge roller or fur brush) 40 by a stirring blade (toner supply auxiliary member) 50,
60 is supplied to the toner supply member 40. On the other hand, the developer carrier (developing roller) 20 of the present invention, which has completed the development, rotates in the direction of the arrow (for example, 400 rpm) and reaches a contact portion with the toner supply member 40. The toner supply member 40 rotates in a direction opposite to the direction of the developer carrier 20 (for example, 300 rpm), applies charge to the developer carrier 20 and the toner 60, and causes the toner 60 to adhere to the developer carrier 20. Further, the developer carrier 20 rotates, and the developer carrier 20 is rotated.
The toner adhered on the upper surface is stabilized by the toner layer thickness regulating member (elastic blade) 30 while controlling the thickness, and reaches the developing region 80. In the development area 80, the latent image is developed by contact or non-contact development. Here, if necessary, a bias such as direct current, alternating current, direct current superimposed alternating current, or pulse can be applied to the developer carrier 20 and the toner supply member 40 to control an optimal image.

Next, the developer carrier used in the present invention will be described. The developer carrier used in the present invention is, as described above,
Although a surface layer made of a conductive material in which insulating particles are dispersed is formed on a conductive substrate,
As a conductive material, 10 ¹² Ωcm or less, preferably 10 ⁸
Ω · cm or less can be used. To be specific, there may be mentioned those obtained by adding a conductivity-imparting agent to organic polymers. In this case, the organic polymers include a resin material (plastomer) and a rubber material (elastomer), and specific examples thereof include the following.

Vinyl resins such as polyvinyl chloride, polyvinyl butyral, polyvinyl alcohol, polyvinylidene chloride, polyvinyl acetate, and polyvinyl formal; polystyrene resins such as polystyrene, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene copolymer; polyethylene , A polyethylene resin such as an ethylene-vinyl acetate copolymer; an acrylic resin such as a polymethyl methacrylate, a polymethyl methacrylate-styrene copolymer; other polyacetal, polyamide, cellulose, polycarbonate, phenoxy resin,
Plastomer materials such as polyester, fluorine resin, polyurethane, phenol resin, urea resin, melamine resin, epoxy resin, unsaturated polyester resin, and silicone resin.

Diene rubbers such as styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), nitrile-butadiene rubber (NBR), nitrile-isoprene rubber (NIR), chloroprene rubber (CR); butyl rubber (IIR) ), Olefin rubbers such as ethylene-propylene rubber (EPM, EPDM) and chlorosulfonated polyethylene (CSM); ether rubbers such as epichlorohydrin rubber (CHR, CHC); other silicone rubbers, fluorine rubbers, acrylic rubbers, urethane rubbers And elastomer materials such as thermoplastic elastomers such as styrene, olefin, polyvinyl chloride, urethane, polyester, polyamide, fluorine and chlorinated polyethylene.

Further, as the conductivity-imparting agent, metal powders such as Ni and Cu;
Carbon blacks such as furnace black, lamp black, thermal black, acetylene black and channel black; conductive oxides such as tin oxide, zinc oxide, molybdenum oxide, antimony oxide and potassium titanate; plating on titanium oxide and mica Electroless plated material; examples include inorganic fillers such as graphite, metal fibers, and carbon fibers, and surfactants.

Further, an organic ion conductor in which metal ions are coordinated to a polymer matrix such as polyethylene oxide or polysiloxane can also be used.

In the case where an elastomer is used in the organic polymer as the conductive material, the surface layer of the developer carrying member becomes elastic, and the contact with the rigid drum-shaped photosensitive member becomes easy, The use of conductive elastomers is particularly preferred, since contact development becomes very easy.

On the other hand, as the insulating particle material, a material having a resistance of 10 ¹³ Ω · cm or more, preferably 10 ¹⁴ Ω · cm is used. The average particle size is preferably 5 μm or more, and more preferably 10 μm or more. If it is less than 5 μm, it is difficult to form a microfield, and stable toner adhesion and charging cannot be obtained. In addition,
Both fixed and irregular shapes are acceptable.

Specific examples of these materials include alumina, beryllia, magnesia, silicon nitride, boron nitride, mullite,
Inorganic particles such as steatite, forsterite, zircon, cordierite, epoxy resin, fluorine resin,
Organic particles such as a silicone resin, an acrylic resin, a polyamide resin, a polystyrene resin, a phenol resin, a melamine resin, and a polyethylene resin are exemplified.

When the conductive elastomer is used as the conductive material, it is preferable to use the elastomer as the insulating particles in order to further promote the low hardness. As the elastomer in this case, the same materials as those exemplified as the elastomer used for the conductive elastomer are used. In order to produce insulating elastomer particles, after freezing the elastomer with dry ice or the like, pulverizing and pulverizing, a method of pulverizing and pulverizing with a grinder, forming an aqueous emulsion using a surfactant or the like, A known method such as a curing method is employed.

In addition, as the elastomer used for the conductive material and the insulating particles, silicone rubber is particularly preferable from the viewpoints of low hardness, environmental resistance, releasability, and the like.

The amount of the insulating particles added to the conductive material is appropriately selected in the range of 10 to 200 parts by weight based on 100 parts by weight of the conductive material. The surface area of the developer carrier is 20-60%
Is preferable, and the amount of the insulating particles to be added is appropriately adjusted so as to be within this range after the preparation of the carrier.

Next, a method for manufacturing the developer carrying member used in the present invention will be described. FIG. 2 shows a typical configuration example (an enlarged partial cross-sectional view of the surface) of the surface of the developer carrying member used in the present invention.
The developer carrier having the surface shown in FIG. 2 is obtained by adding the insulating particles to the conductive material based on a normal dispersion method such as ball milling or kneading, and then subjecting the mixed material to injection molding. , Extrusion, spray coating, dipping, etc., by forming on a conductive substrate typified by a metal roller such as SUS, iron, Al, etc., and then polishing to make the surface smooth It is an example.

Note that a primer can be used to improve the adhesion between the conductive material and the conductive substrate. In this case, the primer is preferably conductive.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to examples. Parts represent parts by weight.

Example 1 Conductive paint (trade name Electrodag 440; manufactured by Acheson Japan) 100 parts (solid content: 70%; acrylic resin containing Ni particles) Acrylic resin particles (average particle size: 80 μm) 50 parts Diluent (trade name: SB-1) 200 parts by Acheson Japan Co., Ltd. 200 parts of the above coating liquid is spray-coated on a SUS metal roller, dried at 80 ° C. for 1 hour, polished, and polished to form a 100 μm-thick developer carrier (developing). Roller).

Example 2 Silicone resin (trade name: SR-2411; manufactured by Toray Silicone Co., Ltd.) 100 parts Ketjen Black EC (manufactured by Akzosimmy Co., Ltd.) 10 parts By the above formulation, ball milling was performed for 72 hours to produce a carbon black master batch.

Masterbatch 100 parts Silicone resin (trade name: SR-2411; manufactured by Toray Silicone Co., Ltd.) 100 parts Insulating silicone particles 50 parts (trade name: Toray Dow Corning
(Manufactured by Silicone Co., Ltd.) (Average particle size: 10 μm) Toluene 100 parts A developing roller was prepared in the same manner as in Example 1 using the coating liquid having the above formulation.

Example 3 Methylvinylsiloxane raw gum 100 parts Fluorosiloxane raw gum 100 parts Dry silica (trade name: R-972; manufactured by Nippon Aerosil Co., Ltd.) 30 parts Fluorosurfactant (Table name: DS-401; manufactured by Daikin Industries, Ltd.) 2 Part: 100 parts of insulating silicone particles (trade name: E-501; manufactured by Toray Dow Corning Silicone Co., Ltd.) (average particle size: 10 μm) After kneading the above mixture with two rolls, 100 parts of the mixture was mixed with a crosslinking agent (2, 1.5 parts of 4-dimethyl-2,4-di-tert-butylperoxyhexane (trade name: RC-4, manufactured by Toray Silicone Co., Ltd.) was added to prepare a molding compound.

A molding compound of the above formulation is applied on a SUS metal roller to which a conductive primer (trade name: DY39-011; manufactured by Toray Silicone Co., Ltd.) has been applied in advance, and primary vulcanization: 170 ° C./1
A surface layer was formed by press molding under the conditions of 0 minute, 120 kgf / cm ² , and secondary vulcanization: 200 ° C. for 4 hours, followed by polishing to prepare a developing roller.

Example 4 Instead of the insulating silicone particles used in Example 3,
Insulating silicone rubber particles (trade name: Trefil E-85)
0; manufactured by Toray Silicone Co., Ltd.)
A developing roller was produced in the same manner as described above.

Evaluation The developing rollers obtained in Examples 1 and 2 were mounted on the developing device shown in FIG. 1, and the amount of toner charge and the amount of toner adhesion were measured. Table 1 shows the results.

In the above-mentioned developing device, the toner thinning blade is made of urethane rubber, the toner supply roller is made of conductive urethane sponge, the toner is positively charged toner, and the photoreceptor generates organic charges on the support. A belt-like photoreceptor having a layer and an organic charge transfer layer sequentially provided was loaded.

From the results shown in Table 1, it can be seen that the developing rollers manufactured according to Examples 1 and 2 can obtain a stable toner adhesion amount and a stable toner charging amount.

Subsequently, with respect to the developing rollers obtained in Examples 3 and 4, the developing device was used, and only the drum OP was used as a photosensitive member.
C was attached, and the charge amount of the toner and the amount of the attached toner were measured in the same manner. Table 2 shows the results.

From the results in Table 2, it can be seen that the developing rollers manufactured in Examples 3 and 4 can obtain a stable toner adhesion amount and toner charging amount and can be easily used in a contact developing device using a drum photosensitive member. You can see what you can do.

〔The invention's effect〕

In the developing device of the present invention, an electrostatic latent image carrier that carries an electrostatic latent image and a developer carrier that carries a developer are opposed to each other in a developing section, and the electrostatic latent image is developed in the developing section. In a developing device for visualizing an image with an agent, the developer carrier has a surface layer in which insulating fine particles are dispersed in a conductive material on a conductive substrate, and charges the insulating fine particles. Means for applying and forming a minute closed electric field near the surface of the developer carrier; and means for supplying a charged developer to the surface of the developer carrier having the minute closed electric field formed near the surface. However, since the developer is carried by the closed electric field, the intensity of the electric field can be remarkably increased by a large number of minute closed electric fields formed in the vicinity of the surface of the developer carrier, and the stable electric field can be obtained. The toner adhesion amount and toner charge amount can be obtained, and Since bearing member can be easily manufactured cost reduction can be achieved.

Further, in the developing device according to the present invention, since a conductive elastomer is used as a conductive material of the developer carrying member, it is very easy to make contact with a rigid drum-shaped photosensitive member. The effect is added.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view centering on a developer carrying portion showing an example of a developing device in which a microfield electric field is formed on a developer carrying member useful for carrying out the present invention. Also,
FIG. 2 is a schematic partial sectional view of the surface of the developer carrier used in the present invention. 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.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Kazuo Nojima, 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company, Ltd. (72) Koji Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Hiroshi Takashima 1-3-6 Nakamagome, Ota-ku, Tokyo Co., Ltd. Inside Ricoh Co., Ltd. (72) Shigekazu Enoki 1-3-6 Nakamagome, Ota-ku, Tokyo Co., Ltd. (56) References JP-A-55-62469 (JP, A) JP-A-2-214874 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 15 / 08

Claims (2)

(57) [Claims] An electrostatic latent image carrier carrying an electrostatic latent image and a developer carrier carrying a developer are opposed to each other in a developing section, and the electrostatic latent image is developed by the developer in the developing section. In a developing device for visualizing an image, the developer carrier has a surface layer in which insulating fine particles are dispersed in a conductive material on a conductive substrate, and imparts a charge to the insulating fine particles. Forming a small closed electric field near the surface of the developer carrying member,
A developing device, comprising: means for supplying a charged developer to the surface of the developer carrier having a small closed electric field formed in the vicinity of the surface, wherein the developer is carried by the closed electric field. 2. The developing device according to claim 1, wherein said conductive material is a conductive elastomer.