JPH0488380A - Electrostatic latent image development method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention supplies a non-magnetic component developer externally added with an auxiliary agent as necessary to a rotationally driven developer carrier, and 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 electrostatic latent image developing method in which an image is visualized 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 carrier and one-component developers that do not contain carrier are known, and two-component developers using the former two-component developer are known. 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 transport the latent image to a visible state 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 Laid-Open No. 61-42672, a layer of dielectric material (insulator) is laminated on the surface of the developer carrier (developing roller). A developer supply member made of, for example, a sponge roller is brought into pressure contact with the dielectric material, and the two are frictionally charged to opposite polarities, and non-magnetic toner charged to the opposite polarity to the dielectric material is electrostatically attached to the dielectric material. A method has been proposed for transporting a darning-component developer 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.

Note that the toner supply member has a resistance of 102 to 10'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 roller, etc., and as a developing roller.

Metal body with uneven surface (Japanese Unexamined Patent Publication No. 60-53976), integrated Mm coated roller (Unexamined Japanese Patent Application No. 55-46768)
Publication) Medium and low antibody coated roller (Japanese Patent Application Laid-Open No. 58-13278
JP-A-53-36245) and an electrode roller having an insulator and a conductive surface (JP-A-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 No. 62-229060 uses an elastic roller, and JP-A No. 61-52663 uses a fur brush or the like to apply an electric charge to the toner through frictional charging between the toner and a replenishing member, and furthermore, by contact with a developing roller. Friction causes the toner to electrostatically adhere 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 charging between the toner replenishing member and the developing roller, but sufficient charging cannot be achieved because the toner-attached member rubs. 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 -10~ for boat fishing.
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.
1-0.3+ag/cB", but 0.3+ag/cB" on the transfer paper.
4-0.511 g/cm" is required, and the amount of toner adhesion is covered by making the speed of the developing roller 3 to 4 times the speed of the photoreceptor.
The problem with rotating the developing roller twice as much is that a phenomenon of "toner from the trailing edge" occurs, that is, when a solid area is developed, the density at 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, with color toner, the degree of coloring is lower than that of black toner, and when trying to improve the "from the rear end of the toner", the color characteristic is even higher than that of black toner, from 0.8 to 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 ZOμC/g (preferably 10 to 15μC/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 auxiliary agent has been externally added as necessary is supplied to a rotating 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 transferred by the developer carried by the developer carrier. In the visual development method, a large number of minute closed 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 method in which an electrostatic latent image is visualized using the developer carried thereon.

In this method, many small closed electric fields (microfields) are formed near the surface of the developer carrier, so the electric field strength can be significantly increased compared to conventional methods, and a large amount of charged non-magnetic toner can be removed. It has many advantages such as being able to be carried on a developer carrier and transported to a developing area.

[Problem to be solved by the invention]

An object of the present invention is to form a large number of microfields near the surface of the developer carrier, hold toner on the carrier by the microfields, and then develop an electrostatic latent image in a development area. In this method, the surface of the developer carrier and the electrostatic latent image carrier are separated in the development region without requiring a troublesome means of maintaining and managing a constant distance between the surface of the developer carrier and the surface of the electrostatic latent image carrier in the development region. The toner is brought into contact with the surface of the latent image carrier, stable triboelectric charging properties are obtained, and the large microfield on the surface of the developer carrier enables the formation of stable multilayer thin layers of toner, resulting in high quality images. The object of the present invention is to provide a developing method that can be obtained.

[Means to solve the problem]

The present invention rotates a developer carrier having a surface elastic layer made of a conductive elastomer in which a large number of insulating micro regions are independently provided on at least the surface of the developer carrier. By bringing into contact with a conductive developer supplying member for supplying the developer to the surface of the developer carrier from a reservoir of a one-component developer made of toner externally added with an adjuvant according to the supplying a developer and triboelectrically charging the insulating region, thereby forming a minute closed electric field on the surface of the developer carrier, and causing the developer to be supported on the developer carrier surface by the minute closed electric field; An electrostatic latent image developing method for visualizing the electrostatic latent image by bringing the developer carrier and a latent image carrier carrying the electrostatic latent image into contact, the method comprising: The present invention provides an electrostatic latent image developing method characterized in that the order is: developer, supply member, and bone-drying region.

The developing method of the present invention eliminates the need for precise gap maintenance, etc. between a rigid latent image carrier such as a photoconductor provided with photoconductivity on a metal drum and a developer carrier. Wide tolerances can be achieved, yet stable triboelectrification can be achieved, and the large microfields create stable multiple thin layers of toner, resulting in high quality images.

The electrostatic latent image developing method will be described below.

FIG. 1 shows an outline of a typical developing device useful for carrying out this developing method, centering on the developer carrier portion. In FIG. 1, toner 60 contained in a toner tank 70 is forcibly brought to a toner supply member (such as a sponge roller or a fur brush) 40 by a stirring blade (toner supply auxiliary member) 50, and the toner 60 is It is supplied to the supply member 40. On the other hand, the developer carrier (developing roller: e.g., 20φ) 20 that has completed the development rotates in the direction of the arrow (e.g., 10100 rpm L, and reaches the contact portion with the toner supply member 40. The toner supply member 40 rotates as the developer carrier The developer carrier 20 and the toner 60 are rotated (for example, at 67 rpm) L in the opposite direction to the developer carrier 20, and the toner 60 is deposited on 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 area 80, the developer carrier 20 and the latent image carrier 10 are brought into rotational contact with each other so that their surfaces are in the same direction (rotational speed of the latent image carrier: 120 rpm, for example), and the surface of the latent image carrier 10 is The latent image is developed. Here, if necessary, a bias 90 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. In addition, setting the amount of deformation of the surface elastic layer on the surface of the developer carrier in the development area to be less than 3710 times the thickness of the elastic layer prevents deformation of the entire developer carrier and prevents contact. Preferable for suppressing vibration generation.

Next, the mechanism of toner adhesion to the developer carrier 20 in the developing method of the present invention will be explained.

An example of the developer carrier 20 is shown in FIG. 2, for example. FIG. 2 is a typical configuration example (enlarged partial sectional view of the surface) of the surface of the developer carrier used in the present invention. The structure is such that the parts are mixed in a small area.

The mechanism of toner adhesion is basically the developer carrier,
This is thought to be due to frictional electrification of the toner supply member and toner. The toner and the dielectric part of the developer carrier are separated in their triboelectrification series, and the toner supply member is located between them. A thin layer is obtained.

The charging polarity of the toner is made positive. Toner is present in the pores and on the surface of the toner supply member. In the optimum charging state, the dielectric portion of the developer carrier is negatively charged due to friction between the toner supply member and the dielectric portion of the developer carrier. Also, when charging the toner and the toner supply member.

Toner is positively charged. The friction between the toner and the dielectric portion of the developer carrier causes the toner to be positively charged and the dielectric portion of the developer carrier to be negatively charged.

If the toner supply member that contributes to bipolar charging is electrically conductive, the charging will be more stable. As a result, stable charging and multiple thin layers are obtained.

Therefore, by setting each member as in the charging series described above, stable triboelectric charging can be obtained, and a stable multilayer thin layer can be obtained by a large micro electric field (micro field).
As a result, uniform speed development between the latent image carrier (photoreceptor) and the developer carrier, which enables high-quality image development, becomes possible.

In addition, in the developing method of the present invention, one of the developer carriers is
#@If a developer carrier made of insulating particle material with a dielectric constant of 4 or less is used as the edge region (dielectric part), a large microfield due to more stable triboelectrification can be obtained, resulting in a more stable multilayer thin film. This is highly preferred since a layer can be obtained.

More specifically, when two materials come into contact and the two surfaces are rubbed, an electric double layer is created at the interface.

This electric double layer charge is stored on each surface when the interface is separated, resulting in triboelectricity. The effect of friction has a large effect of increasing the contact area.

The above is an outline of the definition of triboelectric charging, and electric charge due to friction exists on the surface of an object.

Therefore, it is important to increase the electric field on the developer carrier to increase the holding force of the toner. However, the electric field due to charges on the surface of the developer carrier generated by friction greatly depends on the dielectric constant of the dielectric part of the developer carrier, and by setting the dielectric constant to 4 or less, a large electric field due to more stable frictional electrification can be generated. A micro electric field (micro field) can be obtained, and a more stable multilayer thin layer can be obtained.

As a result, uniform speed development of the latent image carrier and the developer carrier, which enables high-quality image development, becomes possible.

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

As mentioned above, the developer carrier used in the present invention has elasticity, and a typical structure includes a surface made of an elastic conductive material in which insulating particles are dispersed on a conductive substrate. It has a structure in which layers are formed. As a conductive material, 1012Ω・Cl1l or less,
Preferably, one having a resistance of 10''Ω·Cm or less is used.

Specifically, examples include rubber materials (elastomers) in which a conductivity imparting agent is added. Specific examples of rubber materials include the following.

Styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), nitrile-butadiene rubber (NBR), nitrile-isoprene rubber (NI
R), diene rubber such as chloroprene rubber (CR);
Butyl rubber (IIR), ethylene-propylene rubber (E
PM, EPDM), chlorosulfonated polyethylene (C
Olefin rubber such as 5M); Ether rubber such as epichlorohydrin rubber (CHRlCHC); Other silicone rubber, fluororubber, acrylic rubber, urethane rubber, as well as styrene, olefin, polyvinyl chloride, urethane, and polyester rubbers. , elastomer materials such as thermoplastic elastomers such as polyamide-based, fluorine-based, and chlorinated polyethylene-based.

Examples of conductivity imparting agents 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; Inorganic fillers and interfaces such as graphite, metal fibers, and carbon fibers. Examples include activators.

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

On the other hand, as the insulating particle material, those of 10 13 Ω·Cm or more, preferably 10 14 Ω·Cm or less are used. Further, the average particle size is preferably 30 or more, preferably 50 prr1 or more. If the time is less than 30 μs, it is difficult to form a microfield, and stable toner adhesion and charging cannot be obtained. Incidentally, it does not matter whether the shape is regular or irregular, but it is better to use irregularly shaped particles in that the insulating particles do not easily separate from the elastic conductive material.

These specific materials include alumina, beryllia,
Inorganic particles such as magnesia, silicon nitride, boron nitride, mullite, steatite, forsterite, zircon, cordierite, epoxy resin, fluororesin, silicone resin, acrylic resin, polyamide resin, polystyrene resin, phenolic resin, Examples include organic particles such as melamine resin and polyethylene resin.

Further, as the insulating particles, it is preferable to use a nidistomer. As the elastomer in this case, the same material as exemplified as the elastomer used for the conductive elastomer is used.

Insulating elastomer particles can be produced by freezing the elastomer with dry ice or the like and then pulverizing it into powder, by crushing it with a grinder and pulverizing it, or by forming an aqueous emulsion using a surfactant, etc. A known method such as a curing method is employed.

It should be noted that silicone rubber is particularly preferred as the nidistomer used for the conductive material and the MA edge particles from the viewpoint of low hardness, environmental resistance, mold releasability, and the like.

The amount of 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 area of the surface insulation part of the developer carrier is 5
A range of 0 to 80% is preferable, and the amount of insulating particles added is adjusted as appropriate so that it falls within this range after producing the carrier.

Next, a method for producing a developer carrier used in the present invention will be explained. The developer carrier having the surface shown in FIG. 2 is obtained by adding the insulating particles to the conductive material using a conventional dispersion method such as ball milling or kneading.
The mixed material can be molded into SUS, iron, etc. by injection molding, extrusion molding, spray coating, dipping, etc.
This example is produced by molding on a conductive substrate, typically a metal roller, and then polishing the surface to make it smooth.

Note that in order to improve the adhesion between the conductive material and the conductive substrate, it is also possible to use a primer, and in this case, the primer is preferably conductive.

In addition to the structural example of the developer carrier described above, as a method of forming a microfield near the surface of the developer carrier, the surface of the developer carrier is Ii! It is composed of relationships, and -like micro/
There is also a method of directly applying the charge pattern, in which case the insulating surface layer may be made of an elastic rubber material.

When developing while rotating the developer carrier and the latent image carrier in the same direction and at approximately the same speed as shown in FIG. 1, the compression set (JIS K6
301) is preferably 25% or less. This not only allows a sufficient amount of toner to be carried and transported on the developer carrier, but also suppresses vibrations caused by contact rotation with both carriers, eliminating uneven development density. has advantages.

〔Effect of the invention〕

Since the developing method of claim (1) has the above-mentioned configuration, it is troublesome in terms of design to maintain and manage a constant distance between the surface of the developer carrier and the surface of the electrostatic latent image carrier in the development area. In addition to not requiring special means, this method provides stable triboelectric charging, which generates a large microelectric field (microfield) on the surface of the developer carrier.
Multiple thin layers of stable toner are formed, resulting in high quality images. Moreover, high-quality image development can be achieved by uniform speed development between the latent image carrier and the developer carrier.

The developing method according to claim (2) includes 1! of the developer carrier. By setting the dielectric constant of the edge region to 4 or less, the present method provides a larger microfield and forms a more stable multi-thin layer of toner.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a developing device in which a micro-field electric field is formed on a developer carrier useful for carrying out the present invention, with a developer carrier section taken as a cross section. Also,
FIG. 2 is a schematic partial sectional view of the surface of a 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, 90...Bias. Patent applicant Rico Co., Ltd.

Claims (2)

[Claims] (1) A developer carrier having a surface elastic layer made of a conductive elastomer on at least the surface of which is provided with a large number of independently insulating micro regions is rotated, and the surface of the developer carrier is The developer is brought into contact with a conductive developer supplying member for supplying the developer from a reservoir of a one-component developer made of toner externally added with an adjuvant to the surface of the developer carrier. While supplying the agent, the insulating region is triboelectrically charged, thereby forming a minute closed electric field on the surface of the developer carrier, and this minute closed electric field causes the developer to be carried on the surface of the developer carrier, and then An electrostatic latent image developing method in which the electrostatic latent image is visualized by bringing the developer carrier and a latent image carrier carrying the electrostatic latent image into contact with each other. An electrostatic latent image developing method characterized in that the order is: agent - supply member - insulating region. (2) The electrostatic latent image developing method according to claim (1), wherein the dielectric constant of the insulating region is 4 or less.