JPH0812511B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor, particularly an organic photoconductive photoreceptor (OP
The present invention relates to a novel surface image forming method using C).

As a photoconductive material used in an electrophotographic photoreceptor, a-Si,
Inorganic photoconductive materials such as selenium, cadmium sulfide and zinc oxide are known. These photoconductive materials have a number of advantages, such as being able to be charged to an appropriate potential in the dark, having a low dissipation of charges in the dark, or being capable of rapidly dissipating charges by light irradiation. However, it has various drawbacks. For example, selenium-based photoreceptors easily crystallize due to factors such as temperature, humidity, dust, and pressure.In particular, when the ambient temperature exceeds 40 ° C, crystallization becomes noticeable, resulting in reduced chargeability and white spots on images. When there occurs, there is a drawback. Further, the selenium-based photoconductor and the cadmium sulfide-based photoconductor have the drawback that stable sensitivity and durability cannot be obtained during use under high humidity.

Further, the zinc oxide type photoconductor requires a sensitizing effect by a sensitizing dye represented by rose bengal, but such a sensitizing dye causes charge deterioration due to corona charging and photobleaching due to exposure light for a long time. However, it has the drawback that a stable image cannot be provided over the entire length.

Furthermore, various organic photoconductive polymers such as polyvinylcarbazole have been proposed, but these polymers are superior in film-forming property, light weight, and high productivity to the above-mentioned inorganic photoconductive materials. Despite being excellent, it has been difficult to put it into practical use to date because it is inferior to inorganic photoconductive materials in terms of sensitivity, durability characteristics and stability due to environmental changes. Moreover, a suitable sensitizer capable of achieving sufficiently high sensitivity has not been found yet.

For these reasons, in recent years, a lot of low molecular weight organic photoconductive substances have been developed in place of polymer type organic photoconductive substances. The advantage of low molecular weight organic photoconductive substances is that the range of compounds that can be selected has expanded, so by selecting one with good sensitivity and charge retention property, conventional organic photoconductive polymers can be selected. That is, the drawbacks of the photoconductor used can be improved.

As described above, the photoreceptor composed of the organic photoconductor, both low molecular weight type and high molecular weight type, each have excellent characteristics, but on the other hand, the surface hardness is small and it is easily scratched. And, because of this, it is not possible to strongly clean the surface of the photoconductor, and it is difficult to remove low-resistance substances generated on the photoconductor surface by corona discharge, etc., and paper dust and other low-resistance substances attached to the surface. There is a drawback that the substance absorbs water in a humid environment, the resistance is extremely lowered, and the latent image is easily disturbed.

On the other hand, various methods for overcoming such drawbacks of the OPC photoreceptor have been studied, and it has been found that it is effective to use a toner containing fine particles having an appropriate hardness for the OPC photoreceptor such as magnetic powder. I found it.

The present applicant previously proposed a new developing method in Japanese Patent Laid-Open No. 54-43036. It applies a very thin coat of magnetic toner on a sleeve, triboelectrically charges it, then places it in close proximity to the electrostatic image under the action of a magnetic field and develops it without contact.

According to this method, the magnetic toner is applied very thinly on the sleeve to increase the chances of contact between the sleeve and the toner, enabling sufficient triboelectrification, supporting the toner by a magnetic force, and The toner is relatively moved to release the agglomeration of the toner particles and to be sufficiently rubbed with the sleeve. The toner is supported by a magnetic force, and the toner is opposed to the electrostatic image and developed. As a result, an excellent image can be obtained due to prevention of background fog and the like. However, in this method, although the magnetic toner is used, when applied to the OPC photosensitive member, the above-mentioned disturbance of the latent image cannot be eliminated.

Therefore, it is an object of the present invention to provide an image forming method which overcomes the above-mentioned deficiencies and does not cause disturbance of a latent image even in a high temperature and high humidity environment.

That is, the present invention uses a step of forming a developer layer containing a metal oxide fine powder, a metal non-oxide fine powder having a particle size of 0.1 μm or less, and a magnetic toner on a developer holding member and the above developer layer. And the step of visualizing the latent image of the organic photoconductive photosensitive member.

In the present invention, the developer forming the developer layer is
It is composed of a magnetic toner that does not substantially contain a magnetic carrier.

In contrast to the above-mentioned method, the reason that the method of the present invention can overcome the disadvantage that the latent image of the OPC photoconductor tends to be disturbed is presumably because the magnetic toner layer is in contact with the OPC photoconductor.

Examples of the organic photoconductor used in the present invention include those using an organic photoconductive polymer such as polyvinylcarbazole and those using a low molecular weight organic photoconductive substance as an insulating polymer. Among these, a laminated type photoreceptor comprising a charge transporting layer and a charge generating layer is preferably used in the present invention. The charge generating layer includes azo pigments such as Sudan Red, Diane Blue and Dienas Green B, Argol Yellow and Pyrenequinone, Indanthrene Brilliant Violet RRP and other quinone pigments, quinocyanine pigments, perylene pigments, indigo and thioindigo and other indigo pigments, Indofast orange toner and other bisbenzimidazole pigments, copper phthalocyanine and other phthalocyanine pigments, quinacridone pigments and other charges It is formed by dispersing a generative substance in a binder resin such as polyester, polystyrene, polyvinyl butyral, polyvinyl pyrrolidone, methyl cellulose, polyacrylic acid esters, and cellulose ester. The thickness is 0.01 to 1 μ, preferably 0.05 to 0.5 μ.

Further, the charge transport layer has a main chain or a side chain of anthracene, pyrene, phenanthrene, polycyclic aromatic compound such as coronene or indole, carbazole, oxazole, isoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline, thiadiazole,
A compound having a nitrogen-containing cyclic compound such as triazole,
It is formed by dissolving a hole transporting substance such as a hydrazone compound in a resin having a film forming property. This is because the charge transporting substance generally has a low molecular weight and is poor in film forming property by itself. Examples of such a resin include polycarbonate, polymethacrylic acid esters, polyarylate, polystyrene, polyester, polysulfone, styrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer and the like.
Is preferred. As the resin constituting the surface layer of the photoreceptor such as the charge transport layer, properties such as abrasion resistance and oil lubricity are also important, and from such a point, at the peak position measured by DSC as a resin. It is preferable that Tg is 60 ° C. or higher, particularly 80 ° C. or higher.

Further, the hardness of the surface of the OPC photoreceptor used in the present invention,
It is preferably 10 g or more, and particularly preferably 12 to 100 g as measured by the method described below. The hardness is measured as follows.

Fix the OPC photoconductor on the sample stand of HEIDON14 type surface profilometer (Shinto Scientific Co., Ltd.), and attach the diamond needle to the OPC photoconductor (conical, cone angle is 90 °, but the tip is 0.01 mm in diameter).
It has a hemispherical shape of mm. ), A vertical load xg is applied, the sample stage is moved at a speed of 50 mm / min, and the surface of the OPC photoconductor is scratched. The width of this scratch is, for example, a micro hardness tester MV
Measure with a microscope attached to K-F (manufactured by Akashi Seisakusho).

The above operation, load xg for example 10g, 15g, 20g, 25g, 30g,
Repeat the procedure for 35g, 40g, ..., and calculate the load that gives a 50μ scratch from the linear regression relationship between the scratch width and the load and use it as the hardness of the OPC photoreceptor. If the OPC photoconductor is a drum, it should be scratched in the axial direction of the drum.
Set the OPC photoreceptor on the sample.

Further, those containing a vinyl polymer in an amount of 30% by weight or more, more preferably 50% by weight or more, particularly preferably 70% by weight or more are preferable. The vinyl-based polymer is a homopolymer of vinyl-based monomers or a copolymer of two or more vinyl-based monomers, and the vinyl-based monomers include styrene, P-chlorostyrene, vinyltoluene, methyl methacrylate, acrylonitrile, N. It may be a copolymer of a vinyl carbazole or the like and a monomer such as a diene monomer capable of polymerizing with a vinyl monomer.

As the binder resin of the toner used in the present invention, a homopolymer of styrene such as polystyrene, poly-P-chlorostyrene, polyvinyltoluene and the like, or a substitution product thereof; styrene-
P-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer,
Styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene- α-methyl methylmethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer Styrene-based copolymers such as styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, poly Vinyl chloride, poly Vinyl acid, polyethylene, polypropylene, polyester, polyurethane, polyamide,
Epoxy resin, polyvinyl butyral, polyamide,
Polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin,
Aromatic petroleum resins, chlorinated paraffins, paraffin waxes, carnauba waxes, etc. can be used alone or in combination.

Further, as the magnetic powder to be contained in the magnetic toner used in the present invention, a substance which is magnetized by being placed in a magnetic field is used. Iron, cobalt, powder of ferromagnetic metal such as nickel or magnetite, γ-Fe ₂ There are alloys and compounds such as O ₃ and ferrite.

In particular, in order to exert the above-mentioned effects, the BET specific surface area by the nitrogen adsorption method is preferably ² to 20 m ² / g, particularly 2.5 to
12m ² / g is good. The content of the magnetic powder is preferably 10 to 70% by weight based on the weight of the toner.

Further BET specific surface area by the nitrogen adsorption method to the magnetic toner used in the present invention is 0.5 ~ 500 m ² / g, especially 50 ~ 400 m ² / g It is possible to add metal oxide fine powder and metal non-oxide fine powder together. preferable. This is because the addition of such fine powder reduces the above-mentioned disturbance of the latent image. It is considered that such fine powder has a large specific surface area, and thus the low resistance substance adhering to the drum is adsorbed or adhered to the surface of the fine powder to be removed.

That is, the addition of the metal oxide fine powder alone has a great effect in terms of imparting triboelectric charging property and developing durability, but cannot sufficiently exhibit "disorder of latent image". The reason is that the disturbance of the latent image is because a low resistance substance such as ozone-depleted substances on the OPC surface becomes conductive due to high humidity, and the disturbance of the latent image is effective unless the thin layer of this low resistance substance is removed. This is because it cannot be prevented. So the OPC surface must always be fresh. By the way, since the metal non-oxide fine powder having a particle diameter of 0.1 μm or less used in the present invention has a large BET specific surface area, it has a high effect of adsorbing or adhering and removing the low resistance substance. That is, this metal non-oxide fine powder is trapped by the cleaner blade of the electrophotographic process and
This is because the OPC surface is made fresh. The thickness of the thin film to be removed is about 50 to 100Å, which is related to the hardness of the surface layer of the OPC when converted to 3000 sheets, but this change in thickness is irrelevant to the latent image. Such metal oxide fine powders include, for example, alumina, titanium dioxide, barium titanate, magnesium titanate, calcium titanate,
Strontium titanate, zinc oxide, silica sand, clay,
Mica, wollastonite, diatomaceous earth, various inorganic metal oxide pigments, chromium oxide, cerium oxide, red iron oxide, antimony trioxide, zinc oxide-bismuth oxide, bismuth oxide, magnesium oxide, zirconium oxide, beryllium oxide, Pb
_{^{(ZrxTi1-x) o 3,}} Zn (1-x) MnxFe 2 O 4 ( both 0
Powders or particles such as <x <1) may be mentioned, but silica fine powder is particularly preferable.

The silica fine powders referred to here include fine powders having a Si-O-Si bond, both of which are manufactured by a dry method and those which are manufactured by a wet method.

As a method for producing the silica fine powder by a wet method, various conventionally known methods can be applied. For example, if sodium silicate is decomposed by an acid, and if it is shown by a general reaction formula (the following reaction formula is abbreviated), Na ₂ O ・ xSiO ₂ + HCl + H ₂ O → SiO ₂・ nH ₂ O + NaCl, other ammonium salts of sodium silicate or alkali Decomposition by salts, method of generating alkaline earth metal silicate from sodium silicate, then decomposing with acid to silicic acid, method of converting sodium silicate solution into silicic acid by ion exchange resin, natural silicic acid or There is a method of using silicate.

In addition to anhydrous silicon dioxide (silica), any of silicates such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate can be applied to the silica fine powder here. The particle size is preferably in the range of 0.01 to 2 μ as the average primary particle size. Further, those containing 85% by weight or more of SiO ₂ are desirable. The silica fine powder produced by the dry method is so-called dry method silica or fumed silica, and is produced by a conventionally known technique. For example, in the method utilizing the thermal decomposition oxidation reaction of silicon tetrachloride gas in acid-free hydrogen flame, the basic reaction formula is as follows.

SiCl ₄ + 2H ₂ + O ₂ → SiO ₂ + 4HCl Further, in this manufacturing process, for example, by using another metal halogen compound such as aluminum chloride or titanium chloride together with a silicon halogen compound, a fine powder of a composite of silica and another metal oxide can be obtained. It is possible to obtain the body, and the present invention also includes them.

The average particle size of the particles is preferably in the range of 0.001 to 2μ, and particularly preferably 0.002 to 0.2.
It is preferable to use fine silica powder in the range of μ.

Specific examples of these silica fine powders include various commercially available silicas, but those having a hydrophobic group on the surface are preferable, for example, R-972 (manufactured by Aerosil Co., Ltd.), Taranox 500 (manufactured by Tarco Co., Ltd.), etc. Silica coupling agent,
Those treated with a titanium coupling agent, silicone oil, silicone oil having an amine in the side chain or the like are preferable.

As non-oxide fine powder, SiC, AlN, MoSi ₂ , LaB ₆ , B
Examples thereof include metal carbides such as ₄ C, TiC, WC, TiN, Si ₃ N ₄ , MoS ₂ , h-BN, CrC, and AlON, metal nitrides, metal sulfides, and metal silicides. SiC fine powder is particularly preferable.

In the present invention, the particle size of the metal non-oxide fine powder is preferably 0.1 μm or less, and the oil absorption is particularly preferably 5 to 50 ml per 100 g of the non-oxide fine powder.

The production methods of these fine powders are mechanical pulverization, atomization method, sintering method, gas evaporation, plasma evaporation, hydrogen arc heating, oil surface deposition, high frequency induction heating, arc evaporation, thermal decomposition, CVD, gas reduction, Electrolysis, active hydrogen-melting method, etc. are available.

For example, as one example of the CVD method, there are three methods of making TiN as follows.

TiCl Cl (1) 2TiCl ₄ (gas) + N ₂ (gas) → 2TiN (solid) + 4Cl ₂ (gas) (2) 2TiCl ₄ (gas) + N ₂ (gas) + 4H ₂ (gas) → 2TiN (solid) + 8HCl ( gas) (3) TiCl ₄ (gas) + NH ₃ (gas) → TiN (solid) + nHCl + Cl There are two ways to make Si ₃ N ₄ (1) NH ₃ (gas) + H ₂ (gas) + SiCl ₄ (gas) → Si ₃ N ₄ (2) Si (NH ₂ ) ₂ + Si (NH) ₃ → Si ₃ N ₅ H ₃ → Si ₂ N ₃ H → Si ₃ N ₄ Also, as a method of making SiC, CVD of Si crystal and graphite As a sintering method Etc.

The application amount of the metal oxide fine powder and the metal non-oxide fine powder of the present invention is 0.01 for each 100 parts by weight of the magnetic toner.
-10 parts by weight, 0.1-10 parts by weight, the effect is exhibited, and particularly preferably, 0.1-2 parts by weight and 0.1-5 parts by weight are added together.

If necessary, conventionally known carbon black, copper phthalocyanine, iron black, etc. can be used as the coloring material used in the toner used in the present invention, and all conventionally known charge control agents can be used in the present invention. For example, benzyl dimethyl-hexadecyl ammonium chloride, decyl-trimethyl ammonium chloride, nigrosine, safranine γ, and crystal violet metal complex salt.

Further, in the toner of the present invention, if necessary, for example, a lubricant, a conductivity-imparting agent, a fixing aid, etc., such as polytetrafluoroethylene powder, polyvinylidene fluoride powder, a metal salt of a higher fatty acid, carbon black, conductive oxidation, etc. Tin, low molecular weight polyethylene, low molecular weight polypropylene, etc. may be added.

Further, the magnetic toner of the present invention has a volume resistivity of 10 ¹⁰ Ωcm.
More preferably, it is 10 ¹² Ωcm or more. The volume resistivity here means that the toner is molded at a pressure of 100 Kg / cm ² and
It is defined as a value converted from the current value one minute after the application of an electric field of 00V / cm ² .

An example of the developing device used in the present invention is shown in FIG. 1. In the figure, by rotating at least one of the sleeve 3 and the multipolar magnet 4, the magnetic toner 2 is conveyed in the direction of the arrow, and the magnetic toner 2 is a blade. The magnetic toner layer 6 is regulated by 5. The magnetic toner layer 6 formed on the sleeve 3 is set so as to come into contact with the photoconductor 1 in the developing section. A bias voltage may be applied between the sleeve 3 and the photoconductor 1.

The transfer method used in the present invention includes an electrostatic transfer method,
Known methods such as a bias roll method, a pressure path transfer method, and a magnetic transfer method are used. Further, as a method for cleaning the residual toner on the photoconductor, a conventionally known blade cleaning method, a fur brush cleaning method, a magnetic brush cleaning method, or the like is used. Immediately before reaching the cleaning step, a charge removing step or the like may be provided as needed to facilitate toner cleaning.

In the image forming method of the present invention, the blade cleaning method is preferable as an excellent combination with the toner and the photoconductor of the present invention.

Example 1 100 parts by weight of styrene-butyl methacrylate-dimethylamino thier methacrylate (weight ratio 7: 2.5: 0.5) copolymer, 80 parts by weight of magnetite having a BET specific surface area of 5 m ² / g,
3 parts by weight of polyethylene wax are mixed and melt-kneaded by a roll mill. After cooling, coarse pulverization is performed with a hammer mill, and then fine pulverization is performed with a jet pulverizer. Then, classification was performed using an air classifier to obtain a black powder having a particle size of 5 to 20 μm.

On the other hand, while stirring 100 parts by weight of fine silica powder synthesized by a dry method (specific surface area of about 130 m ² / g), 12 parts by weight of silicone oil having an amine in a side chain (viscosity 70 cps at 250 ° C., amine equivalent 830) was added. It was sprayed and maintained at a temperature of approximately 250 ° C. for 60 minutes. The triboelectric charge of the generated treated silica was +130 μc / g.

To 100 parts by weight of the black fine powder, 0.4 parts by weight of silica fine powder treated with silicone oil having an amine in the above side chain and 1.0 part by weight of SiC were added to prepare a developer.

The SiC fine powder is made of silica stone and coke at 1800 to 1900 ° C.
The particles having a particle size of 0.1 μm crushed after the reaction in step 1 were used.

 As for the oil absorption amount, 25 ml of flaxseed oil was adsorbed per 100 g.

The volume resistivity of this developer was 10 ¹⁴ Ωcm.

On the other hand, a photosensitive drum in which a multi-layer opc photoconductor whose charge transport layer has a Tg measured by DSC of 80 ° C or higher and made of methyl methacrylate-styrene (weight ratio 9: 1) copolymer was prepared on a conductive cylinder. Got The hardness of the photoreceptor surface was 21 g as measured by the above-mentioned measuring method.

The photosensitive drum is uniformly charged by corona discharge of −6 kV at a linear surface speed of 66 mm / sec, and then, an original image is irradiated to form a latent image. This latent image is shown in FIG. 1 with a sleeve diameter 50 mm, a sleeve surface magnetic flux density of 700 gauss, a number of magnetic poles of 12, a blade-sleeve gap of 0.4 mm, and a sleeve rotary magnet rotary type developing device for the distance between the photosensitive drum surface and the sleeve surface. Setting to 0.3 mm, a bias voltage of -100V is applied to the sleeve surface, the toner layer formed on the sleeve is contacted with the photosensitive drum using the toner, and developed.
Then, the powder image was transferred from the back surface of the transfer paper while irradiating a corona of -7 kV, and fixed with a heating roll. A clear image was obtained. A running test was performed on 3000 sheets under high temperature and high humidity (32 ° C 90%), but good images without image distortion were obtained.

Example 2 A procedure was performed in the same manner as in Example 1 except that a styrene-acrylonitrile copolymer having a Tg of 80 ° C. or higher was used instead of the methyl methacrylate-styrene copolymer of Example 1. Good results have been obtained. The hardness of the photoconductor surface is
It was 15g.

[Example 3] Silica fine powder synthesized by a dry method (specific surface area of about 200 m ² / g) was used in place of the silica fine powder of Example 1 with 5% aminopropyltriethoxysilane and amino-modified silicone oil (viscosity 750 cps). , Amine equivalent 1900) Fine silica powder produced by treatment with 15% (tribo charge + 160 μc / g)
Was performed in the same manner as in Example 1 except that Si ₃ N ₄ was used instead of SiC in Example 1.

The SiN fine powder used was produced by reacting ammonia gas, hydrogen gas and silicon tetrachloride gas, and had a particle size of 0.08 μm and an oil absorption amount of adsorbed 28 ml of flaxseed oil per 100 g. It was good. The volume resistivity of the developer is 10 ¹⁴ Ωcm.

[Example 4] The same procedure as in Example 1 was carried out except that polymethylmethacrylate having a Tg of 80 ° C or higher was used in place of the methylmethacrylate-styrene copolymer of Example 1, and was good. Results were obtained. The hardness of the photoreceptor surface was 26 g.

[Example 5] γ-F having a BET specific surface area of 6 m ² / g instead of magnetite
When the same procedure as in Example was carried out except that 90 parts by weight of e ² O ₃ was used, a good image without image distortion was obtained.
The volume resistivity of the developer is 10 ¹⁵ Ωcm.

Examples 6 and 7 Almost the same as Example 1 except that magnetite having a BET specific surface area of 3 m ² / g and 10 m ² / g and a surface treated with a titanium coupling agent was used. . Good results have been obtained.

[Example 8] Except for using a toner to which 0.6% of conductive tin oxide having a BET specific surface area of 55 m ² / g was further added, the same operation as in Example 1 was carried out, and favorable results were obtained. .

Furthermore, good results were obtained by using a photoreceptor made of a polymer organic photoconductor using polyvinylcarbazole.

Comparative Example 1 A developer having a volume resistivity of 5 × 10 ¹⁵ Ωcm was prepared in the same manner as in Example 1 except that the SiC fine powder used in Example 1 was changed to have a particle size of 10 μm.

A running test was conducted using the obtained developer under the conditions of high temperature and high humidity in the same manner as in Example 1. As a result, a clear image could not be obtained due to the flow of images from the 1000th sheet.

(Effects of the Invention) As described above, in the image forming method of the present invention, the developer holding member includes the developer layer containing the metal oxide fine powder, the metal non-oxide fine powder having a particle diameter of 0.1 μm or less, and the magnetic toner. And the step of visualizing the latent image of the organic photoconductor by using the developer layer described above. Durability is imparted, and the low resistance substance generated or adhered to the surface of the organic photoconductive photosensitive member is adsorbed or adhered to the surface of the metal non-oxide fine powder having a particle diameter of 0.1 μm or less to be removed, It is possible to obtain a clear image even after the endurance of a large number of sheets without causing the latent image to be disturbed in a high temperature and high humidity environment.

[Brief description of drawings]

FIG. 1 is an illustration of an example of a developing device used in the present invention. 1 ... opc photoconductor 2 ... magnetic toner 3 ... sleeve 4 ... multi-pole magnet 5 ... blade 6 ... magnetic toner layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G03G 15/09 Z

Claims (1)

[Claims] 1. A step of forming a developer layer containing a metal oxide fine powder, a metal non-oxide fine powder having a particle size of 0.1 μm or less and a magnetic toner on a developer holding member, and using the developer layer. Forming a latent image on the organic photoconductive photosensitive member by means of an image forming method.