JPH0431882A - Developer carrier - Google Patents

Abstract

PURPOSE:To reduce rotational torque and to prevent filming from occurring by constituting a developer carrier so that a dielectric part and a conductive part may coexist on the surface of the developer carrier in a state where they have very small areas and setting the surface roughness thereof at <=20mum by Rz reference. CONSTITUTION:The developer carrier 20 is constituted so that the dielectric part and the conductive part may coexist on the surface in the state where they have very small areas, and the surface roughness thereof is <=20mum by the Rz reference. Provided that the Rz means ten-point average roughness specified in JIS B 0601 and it expresses the value of a difference between the average of the heights from the highest peak to the fifth highest peak and the average of the heights from the deepest trough to the fifth deepest trough which are measured from a line which is parallel with an average line and does not intersect a cross sectional curve in the direction of axial magnification at a part obtained by extracting a reference length from the cross sectional curve by micrometer(mum). Thus, the rotational torque is reduced, the device is miniaturized and a jitter phenomenon is eliminated, then the filming of toner is restrained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention supplies a non-magnetic one-component developer externally added with an auxiliary agent as necessary to a developer carrier that is rotatably moved. , the developer is carried on the surface of the developer carrier, and the electrostatic latent formed on the latent image carrier is transported in a development area where the latent image carrier and the developer carrier face each other. The present invention relates to a developer carrier used in an image forming method in which an image is visualized by the developer carried on the 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/carrier mixing ratio fluctuations are likely to occur, equipment maintenance is complicated, and the overall structure of the equipment tends to increase in size. It has its drawbacks.

From this point of view, a one-component development system using a -component developer, which does not have the above-mentioned drawbacks, is attracting attention. - Component-based developers include those consisting only of toner and those consisting of a mixture of toner and auxiliary agent, with external addition of an auxiliary agent 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.

By the way, 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.

In addition, in a developing device that uses a -component development method,
- A component-based developer is carried on a developer carrier and transported, and an electrostatic latent image formed on the latent image carrier is developed in a development area where the developer carrier and the latent image carrier face each other. However, in order to form a high-quality visible image with a predetermined density, a large amount of sufficiently charged toner is transported to the development area, and the latent image is made visible by the toner. There is a need.

When magnetic toner is used, the one-component developer can be supported on the developer carrier by utilizing the magnetic force of a magnet inside the developer carrier, so the above requirements can be met relatively easily. It 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 a developer carrier (developing roller), and a developer supplying member made of, for example, a sponge roller is brought into pressure contact with this layer, so that the two have different polarities. At the same time as triboelectrically charging, non-magnetic toner charged to the opposite polarity to the dielectric is electrostatically attached to the dielectric.
A method of transporting such a -component developer to a development area has been proposed. 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 image roller, and the toner cannot be transported to the development area. Due to the insufficient amount of developer, it is difficult to form a visible image with high density.

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 10'Ω・C
(1) 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 an insulator and a conductive surface (Japanese Unexamined Patent Publication No. 53-36245).

Furthermore, in a developing device using a non-magnetic component developer,
A sponge roller is used in JP-A-62-229057, an elastic roller is used in JP-A-62-229060, and a fur brush is used in JP-A-61-52663 to reduce frictional charging between toner and a replenishing member. This applies an electric charge to the toner, and furthermore, due to the friction when it comes into contact with the developing roller,
Toner is electrostatically attached to the developing roller, and a layer thickness regulating member such as a blade is used to control the toner layer to develop the latent image on the photoreceptor. 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. <<, resulting 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 generally lO~
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.
1J, 3mg/cm", but 0.4-
0.511 g/cm" 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. Rotation has a problem in that it causes a phenomenon of ``toner from the trailing edge'', that is, when a solid area is developed, the density of the trailing edge of the image becomes higher.

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, color toner has a lower degree of coloring than black toner, and when trying to improve "from the trailing edge of the toner", it requires an even larger layer of 0.8 to 1.2 g/c compared to black toner. An amount of adhesion on the developing roller of -2 is required.

In addition, regarding the amount of charge, in order to obtain a stable image, 5 to 20 μC/g (preferably 10 to 15 μC/g)
A value of is desired.

As a method to solve these problems, the present inventors
First, ``To the developer carrier that is rotationally driven.

A one-component developer consisting of a non-magnetic toner to which an auxiliary agent is externally added as necessary is supplied, the developer is carried on the surface of the carrier, and the developer is conveyed to the latent image carrier and the developer carrier. In the developing method, an electrostatic latent image formed on the latent image carrier is visualized by the developer carried on the developer carrier in a development area where the developer carrier is opposite to each other. By selectively retaining charges on the surface, a large number of minute closed electric fields are formed near the surface of the carrier, and the charged toner is attracted by the closed electric field, and the developer is attached to the surface of the developer carrier and carried. and proposed an image-forming method in which an electrostatic latent image is visualized using the developer carried thereon.

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

[Problem to be solved by the invention]

However, even in the image forming method in which a large number of microfields are formed near the surface of the developer carrier as described above, there are many members on the developer carrier, such as a toner supply member, a toner layer thickness regulating member, (during contact development) a photoreceptor, etc. is in contact with the photoreceptor. Therefore, if the surface roughness of the developer carrier is large, the rotational torque of the developer carrier increases, and
There are disadvantages in that jitter phenomenon occurs due to vibration, and furthermore, a powerful motor is required, leading to an increase in the size and cost of the device. Furthermore, the toner on the developer carrier becomes insufficiently stirred, resulting in so-called filming development in which the toner sticks to the surface of the developer carrier, and furthermore, the amount of charge on the toner becomes insufficient. There is a point.

Therefore, an object of the present invention is to provide the above-mentioned image forming method in which rotational torque can be reduced and there is no jitter phenomenon.
Moreover, it is an object of the present invention to provide a developer carrier that eliminates the problems of filming and insufficient toner charge.

[Means to solve the problem]

As a result of extensive studies, the present inventors found that a developer carrier having a specific surface roughness is suitable for the above purpose, and completed the present invention.

That is, according to the present invention, on the surface of the developer carrier,
By selectively retaining electric charge, a large number of minute closed electric fields are formed near the surface of the developer carrier, and a non-magnetic film made of toner to which an auxiliary agent is externally added as necessary is placed on the developer carrier. A developer carrier used in an image forming method in which a component-based developer is supplied, the developer is carried on the surface of the developer carrier by the minute closed electric field, and an electrostatic latent image is visualized by the carried developer. Provided is a developer carrier, characterized in that the surface thereof has a dielectric portion and a conductor portion coexisting in a small area, and has a surface roughness of 20 − or less based on RZ standard. be done.

In the image forming method using the developer carrier of the present invention, since a large number of minute closed electric fields are formed near the surface of the developer carrier, the electric field strength can be significantly increased compared to the conventional method. Since the developer carrier has a specific surface roughness, the coefficient of friction on the surface of the developer carrier is reduced, and as a result, toner filming does not occur, and a large amount of sufficiently charged non-magnetic toner is transferred to the developer carrier. It can be carried on the substrate and transported to the developing area.

In addition, in the present invention, since the rotational torque is reduced, 1
Since there is no need to use a powerful motor, the apparatus can be made more compact, and furthermore, it is possible to prevent image disturbances caused by jitter phenomena, thereby providing high-quality copied images.

This image forming method will be explained below.

FIG. 1 shows an outline of a typical developing device useful for carrying out this image forming method, centering on the developer carrier section.
0 is a toner supply member (sponge roller, fur brush, etc.) 4 by a stirring blade (toner supply auxiliary member) 50.
0, the toner 60 is forcibly brought to the toner supply member 4
0. On the other hand, the developer carrier (developing roller) 20 of the present invention, which has completed the development, is rotated in the direction of the arrow (for example, 400 rpm) I, and reaches the contact portion with the toner supply member 40. The toner supply member 40 rotates in the opposite direction to the developer carrier 20 (for example, at 300 rpm), charges 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 toner adhering to the developer carrier 20 is removed by the 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 zone 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.

As an example of the developer carrier 20, as shown in FIG. 2, the developer carrier 20 is configured such that a dielectric portion and a conductor portion coexist in a small area on its surface.

The size of the area is, if the shape is circular, the diameter is 1
Micro areas with a size of 0 to 500 pa are distributed randomly or according to a certain rule. As for the area ratio, the area of the insulating portion is preferably in the range of 20 to 60%.

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 toner supply member 40 . The remaining toner in the non-image area that has not been developed is mechanically and electrically scraped off by the toner supply member 40, and the dielectric portion is charged by friction. At this time, the charges on the developer carrier 20 and toner due to the previous development are as follows:
The toner transported by the supply member 40 is charged by friction and electrostatically adheres to the dielectric portion of the developer carrier 20 . At this time, the polarity of the toner is opposite to the charge on the photoreceptor, and the dielectric portion of the developer carrier 20 is of the same polarity.

At this time, the electric field on the developer carrier 20 becomes a microfield (closed electric field) as shown in FIG. 2, and becomes an electric field with a large electric field gradient, making it possible to adhere the 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. This toner layer further has a toner layer thickness jl
The toner layer thickness is controlled by the T control member 30, and the developing area 80
The toner becomes an electric field that easily adheres to the photoreceptor, and development is performed.

Next, the developer carrier of the present invention will be explained.

As described above, the developer carrier of the present invention is configured such that the dielectric portion and the conductive portion coexist on the surface thereof in a small area, and the surface roughness is 20 − or less based on the RZ standard. It is characterized by

Here, RZ means the ten-point average roughness specified in JIS B 0601, and in the part extracted from the cross-sectional curve by the standard length, the vertical magnification is measured from a straight line that is parallel to the average line and does not cross the cross-sectional curve. The value of the difference between the average elevation of the fifth highest mountain peak and the average elevation of the fifth deepest valley floor measured in the direction of is expressed in micrometers (
pa).

According to the research of the present inventors, when the surface roughness of the developer carrier is set to 20 Ija or less based on the RZ standard, the rotational torque is reduced, the device can be made smaller, and the jitter phenomenon is eliminated. Moreover, toner filming is suppressed,
It has been found that a developer carrier capable of carrying a large amount of sufficiently charged non-magnetic toner can be obtained.

The surface roughness of the developer carrier is 20. If it exceeds the range, the effect of reducing the rotational torque will not be sufficiently exerted, toner filming will occur, and the amount of toner charge will be insufficient, and the effects of the present invention will not be exhibited.

Note that the developer carrier of the present invention is configured such that its surface includes a dielectric portion and a conductive portion, and the surface roughness of either the dielectric portion or the conductive portion is R. , even if it exceeds 20-, the above-mentioned effect does not appear, so the surface roughness of both the dielectric part and the conductor part is set to RZ.
It is necessary to keep it below 20IJs as a standard.

The conductive material used for the conductor part is 1012Ω・0
108 Ω·0m or less. Specific examples include AQ, SO3, Fe, Ni
In addition to metals and ceramics, examples include organic polymers with conductive fillers 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 and acrylonitrile-butadiene-styrene copolymer; polyethylene resins such as polyethylene and ethylene-vinyl acetate copolymer; polymethyl methacrylate, polymethyl methacrylate-tostyrene copolymer, etc. Acrylic resin; polyacetal, polyamide, cellulose, polycarbonate, phenoxy resin, polyester, fluororesin, polyurethane, phenol resin, urea resin, melamine resin, epoxy resin, unsaturated polyester resin, silicone resin, etc. Resin materials: 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.

Examples of 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; and tin oxide.

Conductive oxides such as zinc oxide, molybdenum oxide, antimony oxide, and potassium titanate; electroless plated materials such as titanium oxide and mica; graphite, flying fibers, and carbon fibers.

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

On the other hand, the material used for the dielectric part can be used as long as it is insulating, but the material must have a resistance of 1012Ω・cm or more, especially 10"1Ω
-C- or higher is preferable, and specific examples thereof include the organic polymers listed in the conductive materials.

To manufacture the developer carrier of the present invention, for example, first, a metal roller whose surface is grooved by fleur-de-lis knurling or the like is manufactured. (see Fig. 3(a)), and then apply a fluororesin (Lumiflon LF2) to the grooved metal surface.
; manufactured by G Glass Co., Ltd.) and heated at 100℃ for about 30 minutes.
The roller is cured and dried for several minutes (the coating thickness should be such that the grooves are completely filled) [see Figure 3 (b)), and then the surface of the roller is cut or polished to form a mixture of conductive surfaces in a small area and in a predetermined area. (In this case, the area of the conductive part is made to be 20 to 60%) [see FIG. 3(C)].

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples. Note that 1 part represents a part by weight.

Example 11 100 parts of bloody silicone-modified acrylic urethane resin (trade name UA53; manufactured by Sanyo Chemical Industries, Ltd.; solid content 75 stones) 5 parts of Sn-based catalyst (trade name Cat)
, 55; manufactured by Sanyo Chemical Industries, Ltd.) carbon black fiber
20 copies (product name: Dentol VK-200;
Otsuka Chemical Co., Ltd.) Methyl ethyl ketone
300 copies! Star and Epoxy modified silicone resin 5RZ115 100 parts (TOμ Dow Corning Silicone Company) Curing agent 5RZ11
5K 20 parts (Toμ, Dow Corning Silicone Company) Cellosolve Acetate
200 parts xylene
A developer carrier (developing roller) was prepared in the following manner using 200 parts of the above-mentioned material.

(i) An SO5 roller was coated with the above conductive material by spray coating, cured at 100° C. for 71 hours, and then polished to obtain a conductive layer with a thickness of 50 mm.

(5) Grooves were provided on the roller surface by fleur-de-lis knurling. The V-groove had a recommended pitch of 0.2 and was machined at approximately 45 degrees with respect to the longitudinal direction of the roller.

(iii) The above dielectric material was molded on the V-grooved roller surface in the same manner as in (i). The coating thickness was such that the grooves were completely filled.

(tv) The surface of the roller was polished so that a conductive surface and a dielectric surface coexisted in a small area, so that the conductive part area was 50%.

Comparative Example A developer carrier (developing roller) was produced in the same manner as in the example except that the following material was used as the conductive material.

Seisen Sakuzai 100 parts methyl vinyl polysiloxane 4 parts quartz
15 parts crosslinking agent RC-41,,5
(Dow Corning Silicone Co., Ltd.) Surface roughness and toner filming tests were conducted on the developer carriers obtained in Examples and Comparative Examples using the following method.

Measurement wave: 1.25 ■■ The surface roughness profile of the developing roller surface was measured using the above device, and the Rz of the conductive part and dielectric part was determined based on JIS BO601. Each was calculated.

Attach the toner filming developing roller to the developing device shown in FIG.
After a 0-hour driving test of the developing roller, the toner on the roller surface was blown away with air, the roller surface was transferred with tape, and the filming state of the toner was visually observed.

In the above developing device, the toner thinning blade is made of urethane rubber, the toner supply roller is made of conductive urethane sponge, and the toner is positively charged toner.
Loaded.

Bi-Ai Table 1 shows the measurement results of surface roughness.

From the results in Table 1, it can be seen that the surface roughness of the developer carrier of the present invention is reduced compared to that of the comparative example.

Furthermore, as a result of the filming test, in the example, no toner fusion was observed on the surface of the developer carrier, but in the comparative example, it was observed that the toner was fused almost uniformly on the surface of the carrier. Ta.

〔Effect of the invention〕

Since the developer carrier of the present invention has a surface roughness of 20 or less based on RZ, the rotational torque is reduced, the device can be made smaller, and the jitter phenomenon can be suppressed. I can do it.

Therefore, by selectively retaining electric charges on the surface of the developer carrier, a large number of minute electric fields are formed near the surface of the developer carrier, and an auxiliary electric field is applied on the developer carrier as necessary. 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 developer carrier of the present invention is used in an image forming method in which As a result, toner filming does not occur, and high-density, high-quality images can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view centered on a developer carrier portion showing an example of a developing device in which a microfield electric field is formed on a developer carrier useful for carrying out the present invention. Also,
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. Furthermore, FIGS. 3(a) to 3(C) are schematic cross-sectional views showing the surface state during the manufacturing process of the developer carrier of 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. Patent applicant Rico Co., Ltd.

Claims (1)

[Claims] (1) By selectively retaining electric 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 as needed, A non-magnetic one-component developer made of toner externally added with an adjuvant is supplied, the developer is supported on the surface of the developer carrier by the minute closed electric field, and the electrostatic latent image is made visible by the supported developer. A developer carrier used in an image forming method, which is configured such that a dielectric portion and a conductive portion are mixed in a small area on the surface thereof, and has a surface roughness of 20 μm based on R_Z standard.
A developer carrier having a particle diameter of m or less.