JP2006058639A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus for forming an image by a developing method by which a developer with a stable charge amount is conveyed to a developing region so that a high quality image free of an abnormal image can be obtained, with respect to an image forming apparatus using a two-component developer. <P>SOLUTION: In the image forming apparatus in which an electrostatic latent image on an image carrier is converted to a toner image with a developing device equipped with a developer carrier comprising a nonmagnetic developing sleeve which has a magnetic field generator within the sleeve, bears a two-component developer and rotates, and a developer amount regulating member for regulating the amount of the developer carried on the developer carrier, a carrier in the two-component developer is a carrier for electrostatic latent image development which has a coating film consisting of a binder resin and particles and is obtained by disposing the coating film containing a light-transmissive resin on a true spherical magnetic fine powder, and when a multipoint average thickness of optical thickness of the coating film near a vertex of the carrier is represented by d, multipoint variation in the coating film is within a range of ≤0.1d μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus that forms an image using a developing method such as a copying machine, a facsimile machine, or a printer. More specifically, the present invention relates to an image using a developing method that uses a two-component developer composed of a specific carrier and toner. The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying apparatus, a two-component developing apparatus that performs development using a two-component developer composed of a carrier for developing an electrostatic latent image having magnetism and toner, and a toner only. A one-component developing device that performs development is known.

  The two-component developing device usually includes a developing sleeve that is a cylindrical developer carrying member that includes a magnet roller including a magnet body having a plurality of magnetic poles therein and is rotatably supported. While carrying the carrier for developing an electrostatic latent image with toner attached to the surface of the developing sleeve, the carrier is conveyed to a developing area that is opposite to the image carrier and developed with a magnetic brush made of a two-component developer. Is. In the two-component developing device, charging is performed by stirring and mixing the carrier for developing the electrostatic latent image and the toner, so that the charging property of the toner is stable and a relatively stable good image can be obtained.

  The above-mentioned electrostatic latent image developing carrier includes prevention of toner filming on the carrier surface, formation of a uniform carrier surface, prevention of surface oxidation, prevention of moisture sensitivity deterioration, protection of the photoreceptor from scratches or abrasion by the carrier, etc. Is desired. Further, it is necessary to extend the life of the developer, control the charge polarity, or adjust the charge amount.

  For this purpose, a hard and high-strength coating layer is usually provided by coating with an appropriate resin material.

  Among them, in the carrier for developing an electrostatic latent image, the light-transmitting coat film covering the surface of the carrier magnetic fine powder is uniform, and the charged state of polarity is caused by friction with a specific toner used together with the carrier. Is required to be obtained stably. In a region having a film thickness of 1 μm or less, since the charge amount increases as the film thickness increases, it is expected that the charge amount varies if the coat film thickness of one carrier varies. Knowing the uniformity (variation) is a very important factor in developing the developer charging design and reliability design.

  That is, if the surface of the carrier coating film is not uniform, the frictional charging between the toner and the carrier becomes unstable, resulting in a reduction in the image quality of the visible image obtained after copying. For example, if the coating film, which is the surface layer of the magnetic fine powder for carriers, is in a non-uniform state that does not maintain smoothness, even if a certain amount of insulating resin is coated, the smooth portion and the valley portion It is inevitable that the coating thickness will be non-uniform, so that non-uniform electrostatic properties will occur in each part of the single particle.

  In particular, in the two-component development, the carrier is held in the gap between the latent image carrier and the developer carrier corresponding to the counter electrode, and the electric property of the carrier carried between the electrodes is in order to form a developing electric field. The problem is that the image quality changes depending on the charge amount of the carrier, which affects the developing electric field.

Conventionally, the film thickness of the coat film is a mass film thickness measurement method for measuring the mass of the coat resin with respect to the magnetic fine powder, a fluorescent X-ray film thickness measurement method for measuring a known silicone film thickness and obtaining the film thickness from a calibration curve, Or it has been measured by film thickness measurement using SEM cross-section observation, which is a destructive inspection, but it is limited to those with low accuracy, those with an average film thickness, and those with a narrow local field of view. However, it has been difficult to know the uniformity of carrier (variation). There are examples of trying to improve the carrier shape (for example, see Patent Document 1) and examples focusing on carrier irregularities (for example, see Patent Document 2). It is impossible to know the uniformity (variation) and design the charging.
Japanese Patent Laid-Open No. 5-34991 Japanese Patent No. 3029180

  The present invention has been made in view of the above background, and an object of the present invention is to convey a developer having a stable charge amount to a development area in an image forming apparatus that forms an image using a two-component developer. Thus, an object of the present invention is to provide an image forming apparatus that forms an image using a developing method capable of obtaining a high-quality image without an abnormal image.

  In order to achieve the above object, the invention according to claim 1 is a two-component developer comprising a carrier for developing an electrostatic latent image and toner having magnetic field generating means fixed therein and having magnetism on the surface. A developing device comprising: a developer carrying member comprising a non-magnetic developing sleeve which carries and rotating; and a developer amount regulating member comprising a rigid body for regulating the amount of developer carried on the developer carrying member. An electrostatic latent image developing device using the electrostatic latent image on the image carrier to form a toner image, wherein the electrostatic latent image developing carrier has a coating film having at least a binder resin and particles, and has a spherical shape. A carrier for developing an electrostatic latent image in which a resin coating layer containing a light-transmitting resin is provided on a magnetic fine powder, and a multipoint average film of the optical film thickness of the coating film near the apex of the carrier for developing an electrostatic latent image When the thickness is d, the coating film variation is 0.1 dμm or less It features to be in the range of.

  Here, the electrostatic latent image developing carrier measures the film thickness of the coating film by utilizing the principle of the “light interference film thickness measurement method” disclosed in Japanese Patent Application No. 2003-133551. The electrostatic latent image developing carrier on which a coating film containing a light-transmitting resin to be measured for film thickness in the electrostatic latent image developing carrier according to claim 1 is formed on a magnetic fine powder on a sphere. There is no particular limitation on the object to be measured as long as a permeable coat film is formed and interference of light reflected between the surface of the magnetic fine powder and the surface of the light transmissive coat film is possible.

  According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the period and amplitude of the irregularities on the surface of the true spherical magnetic fine powder of the electrostatic latent image developing carrier are each 0.1 μm or less. Features.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the thickness of the carrier coat film for developing an electrostatic latent image is from 0.3 μm to 1.5 μm.

  According to the present invention, a non-magnetic developing sleeve having a magnetic field generating means fixed therein and rotating on a surface carrying a two-component developer comprising a carrier for developing an electrostatic latent image having magnetism and toner. And a developer amount regulating member made of a rigid body that regulates the amount of the developer carried on the developer carrying body. In the image forming apparatus for converting an image into a toner image, the carrier for developing an electrostatic latent image has a coating film having at least a binder resin and particles, and includes a light-transmitting resin on a spherical magnetic fine powder. A carrier for developing an electrostatic latent image provided with a coat film, where the multipoint average film thickness of the coat film near the top of the carrier is d, the variation of the multipoint coat film is 0.1 dμm or less. By an image forming apparatus characterized by being a range, In the image forming apparatus using the component developer, the charge amount of stable developer can be conveyed to the developing region, it is possible to obtain a high-quality image without abnormal images such as background fouling.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

  Hereinafter, an embodiment in which the present invention is applied to an image forming apparatus such as a copying machine, a facsimile, or a printer will be described. In the image forming apparatus according to the present exemplary embodiment, a charging device, an exposure device, a developing device, a transfer device, and a cleaning device are sequentially arranged around a photoconductor as an image carrier. In addition, a paper feeding / conveying device that feeds the transfer paper from the paper feeding tray and a fixing device that fixes the toner onto the transfer paper after the transfer paper on which the toner image has been transferred are separated from the photoreceptor.

  In the image forming apparatus configured as described above, the surface of the rotating photoconductor is uniformly charged by the charging device and then irradiated with the laser beam of the exposure device based on the image information to form a latent image on the photoconductor. Form. A toner image is formed by attaching toner charged by a developing device to the electrostatic latent image formed on the photoreceptor. On the other hand, the transfer paper is fed from a paper feed tray by a paper feed / conveyance device, and then conveyed to a transfer portion where the photoconductor and the transfer device face each other. The transfer device applies a charge having a polarity opposite to that of the toner image on the photoconductor to the transfer paper, thereby transferring the toner image formed on the photoconductor to the transfer paper. Next, the transfer paper is separated from the photoconductor, sent to a fixing device, and an image is obtained by fixing the toner to the transfer paper.

  FIG. 2 is a schematic configuration diagram of a developing device of the image forming apparatus according to the present embodiment. The developing device employed in the image forming apparatus will be described in detail with reference to FIG. The developing device 1 is disposed on the side of the photosensitive member 8 and serves as a developer carrying member that carries a two-component developer (hereinafter referred to as a developer) including toner and a carrier for developing an electrostatic latent image on the surface. A non-magnetic developing sleeve 7 is provided. The developing sleeve 7 is attached so as to be partially exposed from an opening formed on the photosensitive member side of the developing casing, and is rotated in the direction of arrow b in the drawing by a driving device (not shown).

  Further, inside the developing sleeve 7, a magnet roller made up of a fixed magnet group as a magnetic field generating means is fixedly arranged. Further, the developing device 1 includes a doctor 9 as a developer regulating member made of a rigid body that regulates the amount of developer carried on the developing sleeve 7. A developer accommodating portion 4 for accommodating the developer is formed on the upstream side of the rotation direction of the developing sleeve 7 with respect to the doctor 9, and the first and second components for stirring and mixing the developer in the developer accommodating portion 4 are formed. Stir screws 5 and 6 are provided.

  Further, a toner replenishing port 10 disposed above the developer accommodating portion 4, a toner hopper 2 filled with toner to be replenished to the developer accommodating portion 4, and a toner feeding device that connects the toner replenishing port 10 and the toner hopper 2. 3 is provided.

  In the developing device 1 configured as described above, the developer in the developer container 4 is agitated by the rotation of the first and second agitating screws 5 and 6, and the toner and the carrier are triboelectrically charged in opposite polarities. Is done. This developer is supplied to the peripheral surface of the developing sleeve 7 that is rotationally driven in the direction of arrow b, and the supplied developer is carried on the peripheral surface of the developing sleeve 7, and the rotation direction of the developing sleeve 7 (arrow) (b direction).

  Next, the amount of the conveyed developer is regulated by the doctor 9, and the regulated developer is conveyed to a development area where the photoconductor 8 and the development sleeve 7 face each other. In this developing area, the toner in the developer is electrostatically transferred to the electrostatic latent image on the surface of the photoconductor 8, and the electrostatic latent image is visualized as a toner image.

  The material of the developing sleeve 7 of the developing device 1 is not particularly limited as long as it is used for a normal developing device. Specifically, nonmagnetic materials such as stainless steel, aluminum and ceramics, and those coated thereon are used. Further, the shape of the developing sleeve is not particularly limited. The doctor 9 has magnetism. Examples of the magnetic material include metal materials such as iron and stainless steel, and resin materials containing magnetic particles such as ferrite and magnetite. Further, another member such as a metal plate made of such a magnetic material may be directly or indirectly fixed to the doctor 9.

  The electrostatic latent image developing carrier includes an electrostatic latent image having a coating film containing at least a binder resin and particles, and a coating film containing a light-transmitting resin on a true spherical magnetic fine powder. A carrier for image development was used, where the multipoint average film thickness of the optical film thickness of the coating film near the top of the carrier is d, and the variation of the multipoint coating film is in the range of 0.1 dμm or less.

  As shown in FIG. 1, in the region of the coat film thickness of 1 μm or less, the charge amount increases as the film thickness increases. Therefore, it is expected that the charge amount varies if the film thickness of one carrier varies. Knowing the average film thickness and uniformity (variation) of the coating film is a very important factor in developing the developer charging design and reliability design.

  The optical film thickness multipoint average film thickness in the present invention can be measured by using a coating layer film thickness measuring method and a film thickness measuring apparatus for a thin film coated fine powder. In the present invention, the average film thickness is defined as the average value of 10 coating films near the apex of a randomly extracted carrier sample for developing an electrostatic latent image. The variation of the coat film is defined as σ given by a statistical standard deviation. As for the surface property of the spherical magnetic fine powder, if the surface property is poor, the coating film is coated depending on the unevenness of the magnetic fine powder, so the surface shape of the magnetic fine powder is reflected as it is. There arises a problem that the coating film varies. For this reason, if the period and amplitude of the irregularities on the surface of the true spherical magnetic fine powder are 0.1 μm or less, the coating film variation is suppressed, and a good image can be obtained.

  Here, the period and amplitude of the irregularities on the surface of the magnetic fine powder are defined as follows. The period is defined as an average of the lengths of adjacent peaks (peaks) and peaks (peaks) extracted from the surface roughness curves in the X and Y directions by a reference length. In addition, the amplitude is extracted from the surface roughness curve in the X direction and the Y direction by the reference length, and the absolute value of the height deviation from the average line of the extracted portion to the measurement curve is summed and averaged. Define.

  The period and amplitude can be measured by the following method. For example, it can be measured by a surface shape measurement method by a vertical scan interferometry using an optical phase shift interferometry and a white interferometry. Specifically, it can be measured using a Wyko NT3300 Optical Profiler manufactured by Veeco or a New View 5000 three-dimensional surface structure analysis microscope manufactured by zygo.

  In addition, a coating film having a thickness of 0.3 μm or more and 1.5 μm or less was used for the electrostatic latent image developing carrier. By setting the coat film thickness to 0.3 μm or more, it is possible to suppress spenting due to the toner. On the other hand, when the coat film thickness exceeds 1.5 μm, the chargeability is deteriorated, and background stains tend to occur on the image. As the true spherical magnetic fine powder, it is preferable to use one having a weight average particle diameter of 20 μm or more from the viewpoint of preventing carrier adhesion to the photoreceptor 8. Moreover, it is preferable to use a thing of 100 micrometers or less from the point of generation | occurrence | production prevention of a carrier stripe etc.

  Specific materials include those known as true spherical magnetic fine powders for two-component developers, for example, iron oxides such as magnetite, γ-iron oxide, ferrite iron, and excess ferrite; iron, cobalt, nickel and the like. Magnetic metal: Complex metal oxide alloy or mixture of iron oxide or magnetic metal and metal such as cobalt, tin, titanium, copper, lead, zinc, magnesium, manganese, aluminum, silicon, etc. Use of carrier, purpose of use May be selected and used as appropriate.

Specific examples of the particles contained in the coat film include alumina and silica. Alumina is preferably a particle having a particle diameter equal to or less than the visible light wavelength, and any surface-treated or non-hydrophobized surface-treated material can be used. In addition, silica used for toner and other silica can be used, and those not surface-treated and those surface-treated such as hydrophobized can be used. The specific resistance of the particles is preferably 10 ¹² Ω · cm or more.

This is because even if the particles are exposed on the surface in a state of having a contact with the core material, charge leakage can be suppressed if it is 10 ¹² Ω · cm or more. Therefore, stable chargeability can be obtained. Further, it is possible to suppress a decrease in charge amount during storage of the developer over a long period of time. Furthermore, the effect is remarkable because the particles are alumina and the content thereof is in the range of 50 to 95 wt%, preferably 70 to 90 wt% of the coating film composition component.

  Furthermore, the effect is remarkable when the particles are silica and the content thereof is in the range of 50 to 95 wt% of the coating film composition component, preferably 70 to 90 wt%. A mixture of alumina and silica may also be used. Further, carbon black or an acidic catalyst can be used alone or in combination as a charging and resistance adjusting agent. Any carbon black that is commonly used for carriers or toners can be used. As the acidic catalyst, one having a catalytic action can be used. For example, it has a reactive group such as a fully alkylated type, a methylol group type, an imino group type, and a methylol / imino group type, but is not limited thereto.

  Examples of the coating resin for the coating film include those known as coating film binding resins for carriers for two-component developers. For example, polyolefin resins such as polyethylene, polypropylene, chlorinated polyethylene, chlorosulfonated polyethylene; polystyrene, acrylic resins (for example, polymethyl methacrylate), polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, Polyvinyl and polyvinylidene resins such as polyvinyl ether and polyvinyl ketone; vinyl chloride-vinyl acetate copolymers; silicone resins composed of organosiloxane bonds or modified products thereof (for example, modified products such as alkyd resins, polyester resins, epoxy resins, polyurethanes, etc.) ); Perhydropolysilazane or modified products thereof (including partially oxidized products); polytetrafluoroethylene, polyvinyl fluoride, polyfluoride Vinylidene, fluorine resins such as polychlorotrifluoroethylene, polyamides, polyesters, polyurethanes, polycarbonates, urea resins, melamine resins, benzoguanamine resins, epoxy resins and the like.

  Among them, preferable coating layer materials for satisfying the constituent requirements of the present invention include silicone resins or modified products thereof, perhydropolysilazane or modified products thereof, fluorine resins, particularly silicone resins or modified products thereof, and the main chain and / or sides. A compound having a siloxane bond skeleton in the chain is more preferred.

  Further, as the toner constituting the developer together with the carrier for developing an electrostatic latent image, toner manufactured by a conventionally known method can be used. Specifically, a mixture comprising a binder resin, a colorant and a polarity control agent is melt kneaded with a hot roll mill, cooled and solidified, and pulverized and classified. Specifically, it is composed of a binder resin, a colorant, a charge control agent, and optional additives as necessary.

  Any known binder resin can be used. For example, styrene such as polystyrene, poly-p-styrene, and polyvinyltoluene, and homopolymers of substituted styrene, styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene -Methyl acrylate polymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer Polymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer Polymer, styrene-maleic acid copolymer Styrene copolymer such as styrene-maleic acid ester copolymer, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, Polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like can be used alone or in combination.

  Further, conventionally known polar control agents for use in toners may be used, such as metal complex salts of monoazo dyes, nitrohumic acids and salts thereof, salicylic acid, naphthoic acid, dicarboxylic acid metal complex amino compounds such as Co, Cr and Fe, There are quaternary ammonium compounds, organic dyes and the like. The amount of the polar control agent used in the toner is uniquely determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method. Although not intended, it is preferably used in the range of 0.1 to 20 parts by weight with respect to 100 parts by weight of the binder resin. If it is less than 0.1 part by weight, the charge amount of the toner is insufficient, which is not practical. On the other hand, when the amount exceeds 20 parts by weight, the charge amount of the toner is too large, and the electrostatic attraction force with the carrier is increased, leading to a decrease in developer fluidity and a decrease in image density. Examples of the black colorant contained in the toner include carbon black, aniline black, furnace black, and lamp black.

  Examples of cyan colorants include phthalocyanine blue, methylene blue, Victoria blue, methyl violet, aniline blue, and ultramarine blue. As the magenta colorant, for example, rhodamine 6G lake, dimethylquinacridone, watching red, rose bengal, rhodamine B, alizarin lake and the like can be used. Examples of yellow colorants include chrome yellow, benzidine yellow, hansa yellow, naphthol yellow, molybdenum orange, quinoline yellow, and tartrazine. Further, the toner can contain a magnetic material and can be used as a magnetic toner. Magnetic materials contained in the magnetic toner include iron oxides such as magnetite, hematite and ferrite, metals such as iron, cobalt and nickel or these metals and aluminum, cobalt, copper, lead, magnesium, tin, zinc and antimony. , Alloys of metals such as beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, vanadium and mixtures thereof.

  These magnetic materials desirably have an average particle diameter of about 0.1 to 2 μm. The amount of the magnetic material contained in the toner is about 20 to 200 parts by weight, particularly preferably 100 parts by weight of the resin component, with respect to 100 parts by weight of the resin component. It is 40-150 weight part with respect to this. Examples of the additive added to the toner include inorganic fine powders such as cerium oxide, silicon oxide, titanium oxide, and silicon carbide. Of these, colloidal silica is particularly preferable. Further, as a release agent for oilless fixing, solid silicone varnish, montan ester wax, oxidized rice wax, low molecular weight polypropylene wax, carnauba wax and the like can be used.

  Examples of the carrier of the present invention and comparative examples will be described in detail below.

(Example)
Acrylic resin solution (solid content 50% by weight) 56.0 parts Guanamin solution (solid content 77% by weight) 15.6 parts Alumina particles [0.3 μm, specific resistance 10 ¹⁴ Ω · cm] 100.0 parts Toluene 900 parts Butyl cellosolve 900 parts These were dispersed with a homomixer for 10 minutes to prepare a coating film forming solution. As the magnetic fine powder on the true sphere, magnetite particles having a surface irregularity period and amplitude of 0.1 μm or less were used. The period and amplitude of the irregularities on the surface of the magnetic fine powder were measured by X and Y-Profile obtained by Wyko NT3300 Optical Profiler. Each of them was 0.08 μm. This coating film forming solution was applied and dried by a Spira coater (Okada Seiko Co., Ltd.) so that the film thickness became 0.6 μm. The film thickness was adjusted by adjusting the amount of the coating solution. The obtained carrier was baked by standing in an electric furnace at 150 ° C. for 1 hour. After cooling, the ferrite powder bulk was crushed using a sieve having an opening of 100 μm to obtain a carrier. Here, the coat film thickness at the apex portion of the randomly extracted electrostatic latent image carrier is measured to calculate a 10-point film thickness measurement value. The average film thickness d = 0.59 μm, variation: σ = 0. 047 μm was obtained. The variation was 0.08d. In addition, the multipoint average film thickness of the optical film thickness of the coat film can be measured by using the coat layer film thickness measuring method and film thickness measuring apparatus of the thin film coated fine powder described in Japanese Patent Application No. 2003-133855.

(Comparative example)
Acrylic resin solution (solid content 50% by weight) 56.0 parts Guanamin solution (solid content 77% by weight) 15.6 parts Alumina particles [0.3 μm, specific resistance 10 ¹⁴ Ω · cm] 160.0 parts Toluene 900 parts Butyl cellosolve 900 parts These were dispersed with a mixer for 10 minutes to prepare a coating film forming solution. As the magnetic fine powder on the true sphere, magnetite particles having a surface irregularity period and amplitude of 0.1 μm or less were used. The period and amplitude of the irregularities on the surface of the magnetic fine powder were measured by X and Y-Profile obtained by Wyko NT3300 Optical Profiler. Each of them was 0.08 μm. This coating film forming solution was applied and dried by a Spira coater (Okada Seiko Co., Ltd.) so that the film thickness became 0.6 μm. The film thickness was adjusted by adjusting the amount of the coating solution. The obtained carrier was baked by standing in an electric furnace at 150 ° C. for 1 hour. After cooling, the ferrite powder bulk was crushed using a sieve having an opening of 100 μm to obtain a carrier. Here, when the average film thickness d and the variation: σ were similarly determined, the variation of the carrier coat film was 0.15d.

(Experiment)
Developers using the carriers of Examples and Comparative Examples were set in the developing device of FIG. A toner containing no wax was used. The developer and the developing device were set on a pre-tail 500 (full color copier manufactured by Ricoh Co., Ltd.) and stirred for 10 minutes in a single color mode. Then, an image was taken and the background stain and image quality of the image portion were confirmed.

  As for the background stain and the image quality, ◎ indicates that there is no problem at all, ○ indicates that there is no problem in practical use, and X indicates that it is inappropriate. An image output using the developer of the example including the carrier of the present invention had a background stain ◎ and an image quality ◎, and good results were obtained. On the other hand, in the comparative example using a developer of a combination of electrostatic latent image developing carrier and toner in which the variation of the multipoint coating film was 0.1 d or more, the background was stained ○ and the image quality was ○. Inferior results were obtained.

  As mentioned above, although the Example of this invention was described, it is not limited to the said Example, A various deformation | transformation is possible in the range which does not deviate from the summary.

It is explanatory drawing which shows the relationship between the carrier coat film thickness of this invention, and a charge amount. FIG. 2 is a configuration diagram of a developing device of an image forming apparatus using the developer of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing apparatus 2 Toner hopper 3 Toner flow apparatus 4 Developer accommodating part 5, 6 Stirring screw 7 Developing sleeve 8 Photoconductor 9 Doctor 10 Toner supply port

Claims (3)

A developer carrier comprising a nonmagnetic developing sleeve having a magnetic field generating means fixed therein and carrying a two-component developer comprising a magnetic latent image developing carrier and toner on the surface and rotating. And an electrostatic latent image on the image carrier is converted into a toner image using a developing device comprising a developer amount regulating member made of a rigid body that regulates the amount of developer carried on the developer carrier. In the image forming apparatus to
The electrostatic latent image developing carrier has a coating film having at least a binder resin and particles, and has a coating film containing a light-transmitting resin on a true spherical magnetic fine powder. Is a career,
When the multipoint average film thickness of the coating film near the apex of the electrostatic latent image developing carrier is d, the variation of the multipoint coating film is in the range of 0.1 dμm or less. Forming equipment.   2. The image forming apparatus according to claim 1, wherein the irregularity period and amplitude of the surface of the spherical magnetic fine powder are each 0.1 μm or less.   The image forming apparatus according to claim 1, wherein the coating film has a thickness of 0.3 μm or more and 1.5 μm or less.

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