JPH0973229A - Developing method for electrophogoraphy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing method by which a clear image with high density and without fogging can be stably formed extending over a long term by stably supplying sufficient toner required for a developing action and to provide an electrophotographic method by which a non-magnetic one-component developing action is realized and the cost of developer, the cost of a device and a running cost can be drastically reduced by using an organic photoreceptor, specially the single-layered organic photoreceptor. SOLUTION: This developing method for electrophotography is constituted so that an elastic developing roller 2 which is coated with non-magnetic one- component toner and on which a toner thin layer is formed by the regulation of a layer thickness regulation member is brought into contact with the photoreceptor on which an electrostatic latent image is formed by an electrostatic charge action and an exposure action. Then, the bulk density of the toner thin layer is set to be 0.35-0.55g/cm<3> and the toner quantity of a developing part is set to be 0.5-0.80mg/cm<2> .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-magnetic one-component developing method used in electrophotography, and more particularly to a developing method capable of always forming a stable image and forming a solid image. .

[0002]

2. Description of the Related Art As a developing system used for electrophotography, a two-component magnetic developing system using a mixture of a toner and a magnetic carrier, a one-component magnetic developing system using a one-component toner containing magnetic powder, and a non-magnetic system. Although a non-magnetic one-component developing method using a one-component toner is known, the non-magnetic one-component developing method is the most excellent in terms of developer cost, developing device cost and easiness of operation. .

In this non-magnetic one-component developing system, a toner image is formed by bringing an elastic developing roller having a thin toner layer formed thereon into contact with a photosensitive member having an electrostatic latent image formed thereon.
If the polarity of the electrostatic latent image (light portion charge) and the polarity of the toner are the same, a negative image is formed by reversal development, and if the polarities are different from each other, a positive image is formed.

As electrophotographic photoreceptors, various photoreceptors such as selenium photoreceptors, a-silicon photoreceptors and organic photoreceptors are known, but in terms of manufacturing cost and small copying machines, fax machines and printers. In terms of adaptability to
The organophotoreceptor is excellent.

[0005]

However, in the non-magnetic one-component developing system, the density and quality of the formed image are extremely sensitive to the thickness of the thin toner layer on the elastic developing roller, and the thickness of the thin toner layer is very small. If it is thick, fogging tends to occur in the non-image portion, while if it is thin, sufficient image density cannot be obtained, and it is difficult to satisfy both clear image quality and high image density at the same time.

Therefore, it is important to regulate the thickness of the toner thin layer by providing a blade for regulating the layer thickness on the elastic developing roller, but it was extremely difficult to regulate this layer thickness. That is, when the regulation force of the blade for regulating the layer thickness is weak, the toner supply amount is sometimes large, sometimes small, and unstable. On the contrary, when the regulation force is too strong, the toner for maintaining a sufficient image density is obtained. It was difficult to supply the amount to the developing section.

Therefore, an object of the present invention is to stably supply a toner necessary and sufficient for development in the above-mentioned non-magnetic one-component developing system, so that a clear image having high density and no fog can be obtained for a long period of time. It is an object of the present invention to provide a developing method capable of forming stably.

Another object of the present invention is to enable non-magnetic one-component development using an organic photoreceptor, especially a single-layer organic photoreceptor, and to significantly reduce developer cost, equipment cost and running cost. The purpose of the present invention is to provide an electrophotographic method that can be used.

[0009]

According to the present invention, an elastic developing roller coated with a non-magnetic mono-component toner and formed with a thin layer of the toner by regulation by a layer thickness regulating member, and charging and exposure. In a developing method for electrophotography, which comprises contacting a photoreceptor on which an electrostatic latent image is formed, a bulk density of a thin toner layer is 0.35 to 0.55 g / cm ³ and an amount of toner in a developing portion is 0.1. 5 to 0.80 mg /
There is provided a developing method in electrophotography, which is characterized in that it is cm ² .

In the present invention, as the non-magnetic one-component toner,
Circularity = spherical toner having a circularity of 0.94 or more, defined by the perimeter of a circle having the same area as the area of the projected toner particles / the length of the contour of the projected toner particles, particularly a spherical toner produced by a polymerization method. Is preferable from the viewpoint of controlling the supply amount of the toner thin layer.

Further, it is preferable to use an organic photoconductor as the photoconductor, particularly a positively charged single-layer organic photoconductor in which a charge generating medium is dispersed in a charge transport medium, from the viewpoint of the cost of the apparatus and the ease of operation.

Further, the charging polarity of the toner and the charging polarity of the dark portion of the photoconductor are set to the same polarity, and the reversal development is performed under the developing condition in which the residual toner on the dark portion of the photoconductor is substantially zero. It is preferable for forming a clear digital image.

The present invention relates to an elastic developing roller coated with a non-magnetic one-component toner and having a thin layer of the toner formed by regulation by a layer thickness regulating member, and a photosensitive member having an electrostatic latent image formed by charging and exposure. The method relates to a developing method in electrophotography in which the toner is in contact with the body, and the bulk density of the thin toner layer is 0.35 to 0.
The high density of 55 g / cm ³ and the amount of toner in the developing area of 0.5 to 0.80 mg / cm ² are remarkable features.

In the non-magnetic one-component developing system of the present invention, the amount of toner in the developing portion (toner weight per unit area) is set within the above range to prevent fogging of the non-image portion while reducing the image density. Is critical to boosting.
This amount can be obtained based on a known area of the developing portion by collecting toner existing in the developing portion by suction and weighing it.

The amount of toner in the developing section is 0.5 g / cm.
If it is less than ² , an image density of 1.2 or more cannot be achieved and a good image cannot be obtained. On the other hand, the toner amount is 0.80
If it exceeds g / cm ² , toner will be accumulated in the developing area and fogging to the non-image area will occur.

In order to stably supply the above-mentioned amount of toner to the developing section and to reliably and sufficiently charge the toner, the bulk density of the toner thin layer is set to a high density of 0.35 to 0.55 g / cm ³ . It becomes important to do. The bulk density of the toner thin layer can be determined by measuring the thickness of the thin layer with a laser thickness meter, collecting the toner weight by suction, and weighing it.

The bulk density of the toner in the thin toner layer is 0.
If it is less than 35 g / cm ³ , the thickness of the toner thin layer for supplying a sufficient amount of toner to the developing section becomes too thick (15
Friction electrification by the thickness regulating member (beyond .mu.m) becomes insufficient, and poorly charged toner is likely to be supplied to the developing section. Further, in the case of such a weak thickness regulation, there is also a drawback that the amount of toner conveyed becomes extremely unstable.

On the other hand, the bulk density of the toner is 0.55 g / cm.
^If it exceeds ³ , the fluidity of the toner is lowered, smooth toner supply becomes difficult, and the thickness regulation of the toner is too strong, so that the photoreceptor is likely to be worn.

In the present invention, the bulk density of the toner in the thin toner layer is regulated to 0.35 to 0.55 g / cm ³ , so that an appropriate amount of toner required for development can be obtained and the thickness of the thin toner layer can be made relatively low. It is possible to suppress and stably secure the toner, and it is possible to satisfactorily perform triboelectric charging by the toner thickness regulating member, and it is possible to supply the sufficiently charged toner to the developing unit. When the true specific gravity of the toner is set to 1 g / cm ³ for simplification, the apparent density of the spherical particles is 0.
Since it is 574 g / cm ³ , the above upper limit of 0.55 g
It will be appreciated that the bulk density of / cm ³ is extremely high. In addition, the bulk density of 0.35 g / cm ³ also means that the average interparticle distance between spherical particles is
It is understood that the distance between the centers is equivalent to about 2.27 times the radius (both particles are completely in contact with each other at twice the radius), and the degree of proximity of the particles to each other is extremely high.

In the present invention, a non-magnetic one-component toner having a circularity of 0.94 or more, particularly 0, is applied to an organic photoconductor, especially a single-layer organic photoconductor in which a charge generating agent is dispersed in a charge transport medium. It is preferable to use a spherical toner having a size of 0.96 or more, and most preferably a spherical toner obtained by a polymerization method. This allows
It is possible to effectively suppress the abrasion of the organic photoconductor, prevent the fog from occurring, and remarkably extend the life thereof.

When a non-magnetic one-component toner is supported on an elastic developing roller to develop an electrostatic latent image on an organic photosensitive member, the elastic developing roller needs to be strongly pressed against the photosensitive member. Since the photoconductor is poor in abrasion resistance, abrasion of the photoconductor surface cannot be ignored. For example, a single-layer organic photoreceptor in which a charge generating agent is dispersed in a charge transport medium,
Non-magnetic one-component toner (roundness =
0.92), the degree of scraping is 1
It is recognized that the number of times reaches 9.5 μm for every 10,000 processes, and fogging occurs in the non-image area. On the other hand, when a spherical toner produced by a polymerization method having a circularity of 1.0 is combined as the non-magnetic one-component toner, the degree of abrasion of the photoconductor is suppressed to 2.3 μm per 10,000 processes. In addition, a clear image can be obtained without fog even after the process of 30,000 times. This has a circularity of 0.
It is recognized that the spherical toner of 94 or more, in particular, the spherical toner produced by the polymerization method has a roller-like lubricating action for the pressure contact between the organic photosensitive member and the elastic developing roller.

In FIG. 1 (explanatory drawing) for explaining the principle of reversal development, an unexposed portion (dark portion) D is charged with a constant polarity, for example, + charge on the surface of the organic photoconductor 1. On the other hand, in the exposed portion (bright portion) L, the charges disappear due to photoconductivity. On the surface of the elastic developing roller 2, a thin layer of toner 3 having a constant polarity, for example, negatively charged, is formed and pressed against the surface of the organic photoconductor 1 at the developing position. Since the charging polarity of the toner 3 and the charging polarity of the dark portion D of the photoconductor are the same positive polarity, the toner 3 is attached and held to the exposed portion (light portion) L by the homopolar repulsion action, and the reversal development is performed. .

According to the present invention, the bulk density of the thin toner layer is set to 0.
High density of 35 to 0.55 g / cm ³ and amount of toner in the developing section of 0.5 to 0.80 mg / cm ^2, and more preferably spherical toner of the above circularity is used, Since the reversal development is performed under the developing condition in which the residual amount of the toner 3 is substantially zero, the dark portion D of the photosensitive member is cleaned during the development, and a clear image is stable for a long time without disturbing the next charging. Can be formed. Further, the toner rejected from the photoconductor dark portion D is effectively used for developing the photoconductor bright portion L.

It is said that a serious drawback of using a spherical toner such as a polymerized toner for electrophotography is poor cleaning of the toner remaining on the photosensitive member after the toner transfer, but in the developing method of the present invention. Since electrostatic cleaning is performed between the toner and the photoconductor at the time of development, the cleaning failure due to the residual toner does not occur.

In the developing method of the present invention, since the non-magnetic one-component toner is used, magnetic powder and magnetic carrier are not required, and the developing device also requires an elastic developing roller, but it is expensive such as a magnet. Along with the use of an organic photoconductor that does not require heavy parts and is inexpensive and easy to dispose of, it is possible to provide a eco-friendly electrophotographic system that reduces the size and weight of the electrophotographic device while reducing the device cost. it can.

Further, when the developing system of the present invention is used, as described above, it is not necessary to perform toner cleaning after the toner transfer and before the main charging of the photosensitive member. Therefore, the cleaning mechanism can be saved and the cleaning can be performed. It is also possible to avoid abrasion of the photoconductor, and it is possible to provide a simplified electrophotographic system at a low cost.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION

[Image Forming Apparatus] In FIG. 2 showing a simplified arrangement of an image forming apparatus to which the developing method of the present invention is applied, a main charging corona charger 11 is provided around the rotary photosensitive drum 6 having the organic photosensitive layer 1 described above. An image exposure optical system 12 including a laser light source, a developing device 13, a transfer mechanism 14, and a charge eliminating light source 15 are arranged. It should be noted that no toner cleaning mechanism is provided.

During image formation, the photosensitive layer 1 of the photosensitive drum 6 is positively and uniformly charged by the corona charger 11. Due to this main charging, the surface potential of the photosensitive layer 1 is generally set in the range of 500 to 800 V in absolute value.

Next, image exposure is performed using laser light from the optical system 12, the potential of the portion corresponding to the light beam image of the photosensitive layer 1 (that is, the laser light irradiation portion) becomes 0 V to 200 V, and the laser light is emitted. Non-illuminated area (background)
Is maintained at the dark decay potential from the main charging potential, and an electrostatic latent image is formed.

The above electrostatic latent image is developed by the developing device 13, and a toner image is formed on the surface of the photosensitive layer 1. The development by the developing device 13 is performed by a developing method (see FIG. 3, described later) using a non-magnetic one-component toner charged to the same polarity as the main charging polarity of the photosensitive layer 1.

The toner image formed on the surface of the photosensitive layer is transferred onto a transfer material 16 such as paper, which is passed between the transfer mechanism 14 and the photosensitive drum 6, and then exposed to light by a light source 15 for static elimination. Static elimination of layer 1 is performed.

In FIG. 3 showing the arrangement of an example of the non-magnetic one-component developing device, inside the developing container 20, there are an elastic developing roller 2 and an elastic developing roller for applying the non-magnetic one-component toner to the photosensitive member. Sub-roller 21 for supplying toner
And an agitator 22 for stirring and mixing the toner. An opening 23 is provided on the side of the developing container 20 close to the photoconductor, and the elastic developing roller 2 is located in the opening 23, and a sub-roller 21 is provided near the developing roller 2. In the upper part of the developing container 20,
A toner container 25 having a slit-shaped opening 24 at its lower end is provided.
6 are provided. Further, a blade 27 for controlling the toner layer to a constant thickness and additionally charging the toner is provided on the toner layer sending side of the elastic developing roller 2.

The non-magnetic one-component toner 3 accommodated in the toner accommodating portion 25 is quantitatively supplied into the developing container 20 by the toner supply roller 26, stirred by the agitator 22 and charged. The charged toner is applied on the sub roller 21 and then on the elastic developing roller 2. The thickness of the toner layer on the developing roller 2 is controlled by the blade 27 so that the toner layer has a constant layer thickness, that is, the amount of toner in the developing section is 0.50 to 0.85 g / cm ² , and The upper toner is strongly charged by rubbing against the blade.

A bias potential having the same polarity as the dark area charge of the photosensitive member is applied to the elastic developing roller 2, and the photosensitive layer 1
At the nip position, and the reversal development is performed according to the principle shown in FIG. It is preferable that a bias voltage slightly higher than the bias voltage applied to the elastic developing roller 2 is applied to the sub roller 21 so that the toner is smoothly transferred from the sub roller 21 to the elastic developing roller 2. .

[Photoreceptor] The organic photoreceptor used in the present invention is
The effect is large when it is an arbitrary organic photoconductor known per se, particularly a single-layer organic photoconductor in which a charge generating agent is dispersed in a resin medium, and the effect is large, and particularly a charge transporting agent, particularly a hole transporting agent and a charge generating agent. The effect is particularly large in the case of a single-dispersion-layer type photoconductor in which is contained in a resin medium.

The photoreceptor of the present invention may, of course, be a laminated photoreceptor of a charge transport layer containing a charge transport agent and a charge generating layer containing a charge generating agent. In this case, the charge generating layer The photoconductor may be one in which (CGL) and the charge transport layer (CTL) are laminated in this order or in the reverse order.

Examples of the charge generating agent include selenium, selenium-tellurium, amorphous silicon, pyrylium salt,
Azo pigments, disazo pigments, ancesthrone pigments,
Phthalocyanine-based pigments, indico-based pigments, selen-based pigments, toluidine-based pigments, pyrazoline-based pigments, perylene-based pigments, quinacridone-based pigments, and the like are exemplified, and one or more of them are mixed so as to have an absorption wavelength range in a desired region. Used.

The following are examples of particularly suitable ones. X-type metal-free phthalocyanine, oxotitanyl phthalocyanine,

Perylene pigments, especially the general formula (1),

Embedded image In the formula, each of R ₁ and R ₂ is a substituted or unsubstituted alkyl group, cycloalkyl group, aryl group, alkaryl group, or aralkyl group having 18 or less carbon atoms. What is represented by Examples of the alkyl group include an ethyl group, a propyl group, a butyl group, and a 2-ethylhexyl group,
Examples of the cycloalkyl group include a cyclohexyl group and the like, examples of the aryl group include a phenyl group and a naphthyl group, and examples of the alkaryl group include a tolyl group, a xylyl group, an ethylphenyl group and the like, and an aralkyl group. Examples thereof include a benzyl group and a phenethyl group. Examples of the substituent include an alkoxy group and a halogen atom.

Bisazo pigments, especially the following formula (2)

Embedded image In the formula, A is a hydrogen atom or a substituted or unsubstituted alkyl group, aryl group or heterocyclic group, n is zero or 1, and Cp is a coupler residue. A substituted or unsubstituted alkyl group, aryl group or heterocyclic group may be bonded to the 3-position of the pyrazole ring directly or via a vinylidene group,
Here, examples of the alkyl group include methyl, ethyl, propyl, butyl, and amyl groups, and examples of the aryl group include phenyl, naphthyl, biphenyl, anthryl, phenanthryl, and fluorenyl groups.As the heterocyclic group, A monocyclic or polycyclic saturated or unsaturated heterocyclic group containing nitrogen, oxygen, sulfur or a combination thereof in the ring, such as a thienyl group, a furyl group, an imidazolyl group,
Pyrrolyl group, pyrimidinyl group, imidazole group, pyrazinyl group, pyrazolinyl group, pyrrolidinyl group, pyranyl group, piperidyl group, piperazinyl group, morpholyl group, pyridyl group, pyrimidyl group, pyrrolidinyl group, pyrrolinyl group, benzofuryl group, benzimidazolyl group, benzofuranyl group , An indolyl group, a quinolyl group, a carbazolyl group, a dibenzofuranyl group and the like. Examples of these substituents include a halogen atom such as a lower alkyl group, a lower alkoxy group, an acyloxy group and chlor, a hydroxyl group, a nitrile group, a nitro group, an amino group, an amide group, an acyloxy group and a carboxyl group. On the other hand, the coupler residue in the formula (2) may be any residue as long as it is a residue of a coupler (azo coupling component) used in this type of azo pigment, such as a substituted or unsubstituted phenol or naphthol. Or a hydroxyl group-containing heterocyclic ring compound or the like, wherein the substituent is a lower alkyl group, a lower alkoxy group, an aryl group, an acyloxy group, a halogen atom such as chlor, a hydroxyl group, a nitrile group, a nitro group, Examples include an amino group, an amide group, an acyloxy group, and a carboxyl group.

Various resins can be used as the resin medium in which the charge generating agent is dispersed, and examples thereof include styrene polymers, acrylic polymers, styrene-acrylic polymers, ethylene-vinyl acetate copolymers, polypropylene,
Olefin polymers such as ionomers, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyester,
Alkyd resin, polyamide, polyurethane, epoxy resin, polycarbonate, polyarylate, polysulfone, diallyl phthalate resin, silicone resin, ketone resin, polyvinyl butyral resin, polyether resin,
Examples include various polymers such as a phenol resin and a photocurable resin such as epoxy acrylate. These binder resins may be used alone or in combination of two or more.
Suitable resins are styrenic polymers, acrylic polymers,
Styrene-acrylic polymer, polyester, alkyd resin, polycarbonate, polyarylate and the like.

Particularly preferred resins are polycarbonate, Panlite manufactured by Teijin Chemicals, PCZ manufactured by Mitsubishi Gas Chemical Co., Ltd., and the following general formula (3):

Embedded image In the formula, R ₃ and R ₄ are hydrogen atoms or lower alkyl groups, and R ₃ and R ₄ may be linked to each other to form a cyclo ring such as a cyclohexane ring together with a bonding carbon atom. It is a polycarbonate derived from the represented bisphenols and phosgene.

As the charge transfer agent, any known electron transfer or hole transfer agent can be used. A suitable example is as follows.

As the electron transfer agent, a paradiphenoquinone derivative, a benzoquinone derivative, a naphthoquinone derivative, tetracyanoethylene, tetracyanoquinodimethane, chloranil, bromoanil, 2,4,7-trinitro-9.
-Fluorenone, 2,4,5,7-tetranitro-9-
Electron-withdrawing substances such as fluorenone, 2,4,7-trinitro-9-dicyanomethylenefluorenone, 2,4,5,7-tetranitroxanthone and 2,4,8-trinitrothioxanthone, and these electron-withdrawing substances Polymerization of the above can be mentioned.

Of these, paradiphenoquinone derivatives, particularly asymmetrical paradiphenoquinone derivatives, are preferable because they are excellent in solubility and electron transporting property.

As the paradiphenoquinone derivative, the following general formula (4),

Embedded image In the formula, each of R ₅ , R ₆ , R ₇ and R ₈ is a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an aralkyl group, an alkoxy group or the like. R ₅ , R ₆ , R ₇ and R ₈ are preferably substituents having an asymmetric structure, and among R ₅ , R ₆ , R ₇ and R ₈ ,
It is preferable that two are lower alkyl groups and the other two are branched chain alkyl groups, cycloalkyl groups, aryl groups or aralkyl groups.

Suitable examples thereof include, but are not limited to:
3,5-dimethyl-3 ′, 5′-di-tert-butyldiphenoquinone, 3,5-dimethoxy-3 ′, 5′-di-tert-butyldiphenoquinone, 3,3′-dimethyl-5,5 '-Di-t-butyldiphenoquinone, 3,5'-dimethyl-
3 ′, 5-di-tert-butyldiphenoquinone, 3,5
3 ', 5'-tetramethyldiphenoquinone, 2,6
2 ′, 6′-tetrat-butyldiphenoquinone, 3,
5,3 ′, 5′-tetraphenyldiphenoquinone, 3,
5,3 ′, 5′-Tetracyclohexyldiphenoquinone and the like can be cited, but these diphenoquinone derivatives have low interaction between molecules due to low molecular symmetry and are excellent in solubility. Preferred for.

On the other hand, as the hole transporting substance, for example, the following substances are known, and among these substances, those having excellent solubility and hole transporting property are used. Pyrene, N-
Ethylcarbazole, N-isopropylcarbazole,
N-methyl-N-phenylhydrazino-3-methylidene-9-carbazole, N, N-diphenylhydrazino-
3-methylidene-9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine, N, N-diphenylhydrazino-3-methylidene-10-ethylphenoxazine, p-Diethylaminobenzaldehyde-N, N-diphenylhydrazone, p-diethylaminobenzaldehyde-α-naphthyl-N-phenylhydrazone, p-pyrrolidinobenzaldehyde-N, N-diphenylhydrazone, 1,3,3
-Trimethylindolenine-ω-aldehyde-N, N-
Hydrazone salts such as diphenylhydrazone, p-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-bis (p-diethylaminophenyl) -1,3,4-oxazizole, 1-phenyl- 3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [quinonyl (2)]-3- (p-diethylaminostyryl) -5-
(P-Diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3- (p-diethylaminostyryl)
-5- (p-diethylaminophenyl) pyrazoline, 1
-[6-Methoxy-pyridyl (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (3)]-3- (p
-Diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [lepidil (3)]-3
-(P-Diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3- (p-diethylaminostyryl) -4-
Methyl-5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3- (α-methyl-p-
Pyrazolines such as diethylaminostyryl) -3- (p-diethylaminophenyl) pyrazoline, 1-phenyl-3- (p-diethylaminostyryl) -4-methyl-5- (p-diethylaminophenyl) pyrazoline and spiropyrazolin, 2 -(P-diethylaminostyryl)
-3-diethylaminobenzoxazole, 2- (p-
Oxazole compounds such as diethylaminophenyl) -4- (p-dimethylaminophenyl) -5- (2-chlorophenyl) oxazole, thiazole compounds such as 2- (p-diethylaminostyryl) -6-diethylaminobenzothiazole, Bis (4-diethylamino-
2-Methylphenyl) phenylmethane and other triaries
Rumethane-based compound, 1,1-bis (4-N, N-diethylamino-2-methylphenyl) heptane, 1,1,
2,2-tetrakis (4-N, N-dimethylamino-2
-Methylphenyl) ethane and other polyarylalkanes, N, N'-diphenyl-N, N'-bis (methylphenyl) benzdiben, N, N'-diphenyl-N, N '
-Bis (ethylphenyl) benzidine, N, N'-diphenyl-N, N'-bis (propylphenyl) benzidine, N, N'-diphenyl-N, N'-bis (butylphenyl) benzidine, N, N'- Bis (isopropylphenyl) benzidine, N, N'-diphenyl-N, N '
-Bis (secondary butylphenyl) benzidine, N, N '
-Diphenyl-N, N'-bis (tertiary butylphenyl) benzidine, N, N'-diphenyl-N, N'-bis (2,4-dimethylphenyl) benzdiene, N, N '
Benzidine-based compounds such as diphenyl-N, N'-bis (chlorophenyl) benzidine, triphenylamine, poly-N-vinylcarbazole, polyvinylpyrene, polyvinylanthracene, polyvinylaridine,
Poly-9-vinylphenylanthracene, pyrene-formaldehyde resin, ethylcarbazole formaldehyde resin.

Suitable examples of the hole transport material are represented by the following formula (5).

Embedded image In the formula, each of Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ is a substituted or unsubstituted aryl group, Y is a substituted or unsubstituted arylene group, and n is a number of 0 or 1. The aromatic amines represented may be mentioned.

Further, other preferable examples of the hole transfer agent include hydrazones, especially the following formula (6).

[Chemical 6] In the formula, each of Ar ₅ may be the same or different, and includes a hydrazone represented by the formula: being a substituted or unsubstituted aryl group.

In the monodisperse type photoreceptor used in the present invention, the charge generating agent (CGM) is preferably contained in the photosensitive layer in an amount of 1 to 7% by weight, particularly 2 to 5% by weight, based on the solid content. , And the charge transfer agent (CTM) is 20 per solid content.
It is preferable that it is contained in the photosensitive layer in an amount of from 70 to 70% by weight, particularly from 25 to 60% by weight.

From the viewpoint of sensitivity and versatility of enabling reversal development, it is preferable to use a combination of an electron transfer agent (ET) and a hole transfer agent (HT). In this case, the ET: HT weight ratio is 10: 1 to 1:10,
In particular, the range of 1: 5 to 1: 1 is the best.

The composition for forming a photoreceptor used in the present invention includes
Various compounding agents known per se, such as antioxidants, radical scavengers, singlet quenchers, UV absorbers, softening agents, surface modifiers, and quenching agents, as long as they do not adversely affect electrophotographic properties. , A filler, a thickener, a dispersion stabilizer, a wax, an acceptor, a donor and the like can be added.

When 0.1 to 50% by weight of the total solid content of a sterically hindered phenolic antioxidant is added,
The durability of the photosensitive layer can be significantly improved without adversely affecting the electrophotographic characteristics.

As the conductive substrate on which the photosensitive layer is provided, various conductive materials can be used, for example, aluminum, copper, tin, platinum, gold, silver, vanadium, molybdenum,
Chromium, cadmium, titanium, nickel, indium,
Examples include simple metals such as stainless steel and brass, plastic materials in which the above metals are vapor-deposited or laminated, and glass covered with aluminum iodide, tin oxide, indium oxide and the like. In the single-layer dispersion type photoreceptor used in the present invention, a normal aluminum tube, particularly a film thickness of 1 to 50 μm is used.
It is preferable to use a blank tube that has been subjected to alumite treatment so as to have m.

In order to form a single dispersion layer type photoreceptor, a charge generating material, a charge transfer agent and the like and a binder resin and the like are prepared by a conventionally known method, for example, a roll mill, a ball mill, an attritor,
It may be prepared using a paint shaker, an ultrasonic disperser, or the like, coated by a conventionally known coating means, and dried. The thickness of the photosensitive layer is not particularly limited, but is preferably in the range of generally 5 to 100 μm, particularly 10 to 50 μm.

As the solvent used for forming the coating solution, various organic solvents can be used, and alcohols such as methanol, ethanol, isopropanol and butanol,
Aliphatic hydrocarbons such as n-hexane, octane and cyclohexane, aromatic hydrocarbons such as benzene, toluene and xylene, halogenated hydrocarbons such as dichloromethane, dichloroethane, carbon tetrachloride and chlorobenzene, dimethyl ether, diethyl ether, tetrahydrofuran, Ethylene glycol dimethyl ether, ethers such as diethylene glycol dimethyl ether, acetone, methyl ethyl ketone, ketones such as cyclohexanone, ethyl acetate, esters such as methyl acetate, dimethylformamide, dimethyl sulfoxide, etc. Used as a mixture. In general, the solid content of the coating solution is preferably 5 to 50%.

Further, in the case of the laminated type photoreceptor, the charge generating agent (CGM) is 30 per solid content of the charge generating layer (CGL).
The amount of the charge transporting agent (CTM) is preferably 20 to 70% by weight, particularly 3% by weight, based on the solid content of the charge transporting layer (CTL).
It is preferably contained in an amount of 0 to 60% by weight. The components of each coating layer conform to the single dispersion layer type components.

CG in the case of substrate / CGL / CTL photoreceptor
L should generally be in the range of 0.1 to 0.5 μm,
The CTL is preferably in the range of 5 to 40 μm, particularly 10 to 25 μm.

In the case of substrate / CTL / CGL photoreceptor, CT
L preferably has a thickness of 5 to 40 μm, in particular 10 to 25 μm, while CGL has a thickness of 0.1 to 0.5 μm. Further, a protective layer known per se can be provided on the CGL.

[Spherical non-magnetic one-component toner] In the present invention,
The bulk density of the toner in the developing section is 0.35 to 0.55 g /
A high density non-magnetic single component toner with a cm ³ is used.
Generally, the bulk density of a powder depends on the shape of the particles, the surface state, the particle size distribution and the like. A powder having a wide particle size distribution tends to have a large bulk density, but in the case of a toner, the fluidity is lowered, so this must be avoided. As already pointed out, a toner with spherical particles and a smooth surface should be used.

As the spherical non-magnetic one-component toner, a spherical toner having a circularity of 0.94 or more, particularly 0.96 or more, and most preferably a spherical toner obtained by a polymerization method in terms of surface smoothness is used. This spherical toner has a composition such as a fixing resin component, a colorant, a high molecular weight or low molecular weight charge control agent,
It contains a release agent, and preferably has a median diameter of 3 to 30 μm, particularly 4 to 20 μm and D25 / D.
Dispersity of particle size represented by 75 is 1.50 or less, especially 1.40
It consists of particles that are monodisperse or close to:
In the present specification, D25 and D75 represent particle diameters corresponding to 25% and 75% of the total volume of toner particles.

Polymerization method A spherical toner is obtained by suspension-polymerizing a toner-forming composition containing at least a radical polymerization initiator, a vinylic monomer that can be a fixing resin, and a colorant in an aqueous medium. .

As long as the circularity is within the above range, spherical toners obtained by other methods can of course be used. For example, an amorphous toner obtained by kneading, pulverizing and classifying a resin composition for toner formation is heated in a hot air stream. Toner that is melted and spheroidized, or a melt of the toner-forming resin composition is sprayed in a hot atmosphere,
A spherically granulated toner is also used for the purpose of the present invention. Hereinafter, a suitable polymerization toner will be described.

The vinyl-based monomer capable of forming the fixing resin is water-insoluble and is capable of forming a thermoplastic resin having a fixing property and an electroscopic property. It is not limited to, but is a vinyl aromatic monomer, an acrylic monomer, a vinyl ester monomer, a vinyl ether monomer, a diolefin monomer, a monoolefin monomer, or the like.

As the vinyl aromatic monomer, the following formula (7) is used.

[Chemical 7] In the formula, R ₉ is a hydrogen atom, a lower alkyl group or a halogen atom, and R ₁₀ is a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, a nitro group or a vinyl group. Vinyl aromatic hydrocarbons such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene,
Examples thereof include o-, m-, p-chlorostyrene, p-ethylstyrene and divinylbenzene, which may be used alone or in combination of two or more.

The acrylic monomer is represented by the following formula (8)

Embedded image In the formula, R ₁₁ is a hydrogen atom or a lower alkyl group, R ₁₂ is a hydrogen atom, a hydrocarbon group having up to 12 carbon atoms, a hydroxyalkyl group, or a vinyl ester group, an acrylic monomer such as methyl acrylate. , Ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexyl methacrylate, methacrylic acid-2
-Ethylhexyl, ethyl β-hydroxyacrylate,
γ-Hydroxy acrylate, δ-hydroxy butyl acrylate, β-hydroxy methacrylate,
Examples thereof include ethylene glycol dimethacrylic acid ester and tetraethylene glycol dimethacrylic acid ester.

Other monomers include vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, etc .: vinyl ethers such as vinyl-n-butyl ether, vinyl phenyl ether, vinyl cyclohexyl ether, etc .: diolefins, especially butadiene. , Isoprene, chloroprene and the like: monoolefins, particularly ethylene, propylene, isobutylene, butene-1, pentene-1, 4-methylpentene-1 and the like. Suitable monomers are styrene monomers, acrylic monomers, styrene-acrylic monomers and the like.

As the colorant for the toner, inorganic or organic pigments and dyes are used, suitable examples of which are as follows. The colorant is preferably used in an amount of 1 to 20% by weight based on the resin in the toner. Black pigment carbon black, acetylene black, lamp black, aniline black. Yellow pigment Yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, hanzer yellow G,
Hansar Yellow 10G, Benzidine Yellow G, Benzidine Yellow GR, Quinoline Yellow Rake, Permanent Yellow NCG, Tartrazine Lake. Orange pigment Red lead yellow molybdenum, molybdenum orange, permanent orange GTR, pyrazolo orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK. Red pigment Bengala, cadmium red, lead red, cadmium mercury sulfide, permanent red 4R, lithol red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B. Purple pigment Manganese purple, fast violet B, methyl violet lake. Blue pigment Navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, fast sky blue, indanthrene blue B
C. Green pigment chrome green, chromium oxide, pigment green B,
Malachite Green Lake, Fanal Yellow Green G. White pigment Zinc white, titanium oxide, antimony white, zinc sulfide. Extender barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white.

As the radical polymerization initiator, known radical polymerization initiators such as azo compound type, hydroperoxide type, peroxide type, peracid type initiator and redox type initiator are used. Suitable examples of initiators include, but are not limited to: 2,2'-Azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-cyclopropylpropionitrile), 2,2'-azobis (4-
Methoxy-2,4-dimethylvaleronitrile), 1,1'-azobis (1-cyclohexanecarbonitrile), benzoyl peroxide, (1-phenylethyl) azodiphenylmethane.

In the toner-forming composition for forming the spherical toner, a toner auxiliary agent known per se can be incorporated.
Examples of the toner auxiliary agent include a charge control agent and a release agent.

As the release agent, polypropylene wax, polyethylene wax, acid-modified products thereof, and the like are used, and these can be contained in the toner forming composition in the emulsion particle size.

The charge control agents are known per se, for example, oil-soluble dyes such as nigrosine base (CI 5045), oil black (CI 26150) and spirone black,
In addition to a naphthenic acid metal salt, a fatty acid metal soap, a metal-containing complex salt dye or the like, a water-soluble monomer having a charge controllable functional group and copolymerizable with the vinyl monomer can be used. Such monomers include sulfonic acid, phosphoric acid, carboxylic acid type anionic groups, or cationic groups such as primary-, secondary- or tertiary-amino groups and quaternary animonium groups. Radical polymerizable monomers having an electrolytic group of,
A suitable example is as follows.

Styrene sulfonic acid, sodium styrene sulfonate, 2-acrylamido 2-methylpropane sulfonic acid, 2-acid phosphooxypropyl methacrylate, 2-acid phosphooxyethyl methacrylate, 3-chloro 2-acid phosphooxypropyl methacrylate, acrylic Acid, methacrylic acid, fumaric acid, crotonic acid, tetrahydroterephthalic acid, itaconic acid, aminostyrene, aminoethyl methacrylate, aminopropyl acrylate, diethylaminopropyl acrylate, γ-N- (N ′, N′-diethylaminoethyl) aminopropyl methacrylate , Trimethylammonium propyl methacrylate.

Furthermore, electrolysis of the above-mentioned sulfonic acid, phosphoric acid, carboxylic acid type anionic groups, or cationic groups such as primary-, secondary- or tertiary-amino groups and quaternary animonium groups. It is also possible to introduce a charge control group at the polymer terminal by using a radical initiator having a polymerizable group.

In the production of the toner by the polymerization method, the toner-forming composition containing a vinyl monomer or the like is suspended in water. In this case, the concentration of the composition is generally 1 to 50.
%, Especially 5 to 30% by weight is suitable and the size of the suspended particles is generally 3 to 30 μm, especially 4 to 20 μm.
It is suitable to adjust to m.

A dispersion stabilizer may be used, if necessary, in order to stabilize the suspension state of the toner-forming composition. Examples of such dispersion stabilizers include polymers soluble in a medium such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, polyacrylic acid, polyacrylamide, polyethylene oxide, poly (hydroxystearic acid-g-methyl methacrylate-CO. -Methacrylic acid) copolymer, nonionic or ionic surfactant, inorganic powder such as calcium phosphate, etc. are appropriately used. The dispersion stabilizer is 0.1 to 10% by weight in the system, especially
It is preferably added in an amount of 0.5 to 5% by weight.

The amount of initiator in the toner-forming composition is 0.3 to 30% by weight, based on the monomers, in particular 0.
It is preferably 5 to 10% by weight.

In the polymerization, the reaction system is replaced with an inert gas such as nitrogen, and the polymerization is carried out at a temperature of 40 to 100 ° C., particularly 50 to 90 ° C. while maintaining the above-mentioned suspension state. Of course, mild agitation may be performed to homogenize the reaction system. Since the polymerization product after the reaction is obtained in the form of granules having the above-mentioned particle size range, the produced particles are filtered, washed with water or a suitable solvent if necessary, and dried to obtain toner particles.

For the toner particles, improving the fluidity of the particles is effective for increasing the bulk density,
Generally, the toner preferably has an angle of repose of 40 degrees or less. For this purpose, a fluidity improving agent such as carbon black, hydrophobic amorphous silica, hydrophobic finely powdered alumina, fine titanium oxide and fine spherical resin is sprinkled to obtain a final toner. Flowability improver is 0.1 to 2% by weight per toner
It is good to use in the amount of.

[Elastic Body Developing Roller] Elastic Body Developing Roller 2
As the material, a roller obtained by molding a composition obtained by mixing a conductive powder with an elastomer polymer is used.

The resistance between the core and the surface of this elastic developing roller is generally 10 ^{4 to} 10 ⁹ Ω, particularly 10 ^{5 to} 10 ^8.
It is preferably in the range of Ω, and when it is higher than the above range, it is difficult to apply the bias voltage. On the other hand, when it is lower than the above range, there is a tendency that leakage due to discharge occurs on the surface of the photoconductor.

Further, the surface hardness (JI
S A) is 30 ° to 70 °, especially 40 ° to 60 °
The range is preferably higher than the above range, and if it is higher than the above range, it tends to be difficult to bring the toner layer into uniform contact with the surface of the photoconductor, or the photoconductor tends to be abraded. When it is lower than the range, it becomes difficult to transmit a sufficient pressure contact force, and the developing roller is easily worn.

As the elastomer polymer, for example, nitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), polybutadiene (BR), polyisoprene (IIB), butyl rubber, natural rubber, ethylene- Propylene rubber (EP
R), ethylene-propylene-diene rubber (EPD)
M), polyurethane, silicone rubber, fluorine rubber, chlorinated polyethylene, chlorinated polypropylene, soft vinyl chloride resin and the like can be used. In order to adjust the surface hardness, a foam (sponge) can be used, or a plasticizer or a softener can be blended.

In forming the conductive rubber roller,
A compounding agent known per se, for example, a sulfur or organic vulcanizing agent, a vulcanization accelerator, a softening agent, an antioxidant, a filler, a dispersant, a plasticizer, a foaming agent, etc. Can be blended. The molded rubber roller is heated to be vulcanized or vulcanized and foamed to obtain an elastic developing roller having a predetermined hardness.

[Development Conditions] In the present invention, an organic photosensitive drum having a relatively small diameter, for example, an outer diameter (Dp) of 10 to 80 is used.
It can be advantageously applied to an organic photoreceptor having a thickness of 15 mm, particularly 15 to 40 mm.

On the other hand, as the elastic developing roller, for example, the outer diameter (Dd) is 5 to 30 mm, particularly 10 to 20 mm.
Roller is used, and the ratio (Dd / Dp) between the diameter of the elastic developing roller and the diameter of the organic photosensitive drum is 1/5 to 1 /
It is preferably in the range of 1, especially 1/3 to 1 / 1.2.

If the diameter of the elastic developing roller is smaller than the above range, the problem of toner scattering tends to occur. On the other hand, if it is larger than the above range, the area of the developing portion becomes too large, which is not preferable.

At the time of development, the elastic roller is set to 0.05 to 1 kg / dm, particularly 0.08 to 0.
The pressure roller is brought into pressure contact with a linear pressure of 5 kg / dm, and the peripheral speed of the elastic roller is 1.
The peripheral speed is preferably 2 to 3.0 times, particularly 1.5 to 2.5 times.

When the pressure contact force is lower than the above range or when the peripheral speed of the elastic developing roller is lower than the above range,
It is difficult to sufficiently improve the image density, and there is a tendency that cleaning in the dark portion of the photoconductor cannot be performed sufficiently. On the other hand, when the pressure contact force is higher than the above range or the peripheral speed of the elastic developing roller Is larger than the above range, the amount of abrasion of the photoconductor increases, and the life of the photoconductor tends to be shortened.

The elastic roller has the same polarity as the charging potential of the toner and has a photosensitive member potential (dark portion potential) of 0.2 to 0.
It is preferable to apply a bias potential of 8 times, especially 0.3 to 0.7 times. If the bias potential is lower than the above range, a sufficient image density cannot be obtained. The toner cleaning of the dark portion of the photoreceptor is not performed sufficiently, and fogging occurs. Also, the supply of toner is insufficient, and the image density tends to decrease.

In the developing device shown in FIG. 3, it is preferable to apply a bias voltage to the sub-roller as well, and the bias voltage applied to the sub-roller has the same polarity as the bias voltage applied to the elastic developing roller, and is zero than that. It is preferable that the voltage is as high as about 200 V in order to smoothly transfer the toner from the sub roller to the elastic developing roller.

The thickness of the toner layer on the elastic developing roller is
Although regulated by a blade, it is generally preferable to form about two times the toner particle size, that is, to form about two toner layers.

[0094]

The present invention will be described in the following examples. Example 1 Styrene 80 parts by weight n-Butyl methacrylate 20 parts by weight Carbon black 5 parts by weight Diethylene glycol dimethacrylate 2 parts by weight Bontron N07 0.5 parts by weight Azobisisobutyl valeronitrile 3.5 parts by weight Sufficient for each of the above components by a stirrer It was dispersed and dissolved to obtain a polymerization composition. To the polymerization composition, 400 parts by weight of water containing 20 parts by weight of tricalcium phosphate was added to a suspension stabilizer, and T. K. Rotation speed 10,0 using a homomixer
An oil extract of the polymerizable toner composition was obtained by stirring at 00 rpm. Then, under a nitrogen stream, washing with dilute hydrochloric acid is performed to dissolve and remove tricalcium phosphate,
The polymerized toner having an average particle size of 10 μm and a circularity of 0.99 was obtained by washing with ion-exchanged water and further sufficiently drying. To 100 parts by weight of the obtained toner,
0.16 parts by weight of hydrophobic silica was externally added. Using this toner, a urethane rubber roller as an elastic developing roller, and a contact developing system "TC-650" (manufactured by Mita Kogyo Co., Ltd.) modified with a layer thickness regulating blade having a linear pressure of 200 g / dm3, 30,000 sheets. Was tested. The results are shown in Table 1. 3
Fogging did not occur even after copying 10,000 sheets, and a clear image was obtained.

Example 2 A copying test was conducted in the same manner as in Example 1 except that 0.8 part by weight of hydrophobic silica was externally added and the linear pressure of the layer thickness controlling blade was set to 150 g / dm.

Example 3 The same formulation as in Example 1 was used for T. K. By rotating the homomixer at 12,000 rpm, the average particle size is 8 μm.
Toner was obtained. 0.5 weight part of hydrophobic silica is externally added to this toner, and the linear pressure of the layer thickness regulating blade is set to 80 g / dm.
A copying test was conducted in the same manner as in Example 1 except that the above was used.
Table 1 shows the test results.

COMPARATIVE EXAMPLE 1 The polymerized toner used in Example 1 was subjected to a copy test without surface treatment. Table 1 shows the test results.

Comparative Example 2 0.16 parts by weight of hydrophobic silica was externally added to a toner having an average particle size of 10 μm obtained by a usual pulverization method, and a copying test was conducted in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3 A copying test was conducted in the same manner as in Example 1 except that the linear pressure of the layer thickness regulating blade was set to 10 g / dm. The results are shown in Table 1.

[0100]

[Table 1]

[0101]

According to the present invention, in the electrophotographic developing method using the non-magnetic one-component toner, the bulk density of the thin toner layer is 0.35 to 0.55 g / cm ³ and the toner amount in the developing portion is 0.5. By setting the amount to 0.80 mg / cm ² , it is possible to stably supply the toner necessary and sufficient for development, and it is possible to form a clear image with high density and without fog for a long period of time.

In the developing method of the present invention, since the non-magnetic one-component toner is used, the magnetic powder or the magnetic carrier is unnecessary, and the developing device also needs the elastic developing roller, but it is expensive such as a magnet. Along with the use of an organic photoconductor that does not require heavy parts and is inexpensive and easy to dispose of, it is possible to provide a eco-friendly electrophotographic system that reduces the size and weight of the electrophotographic device while reducing the device cost. it can.

Further, when the developing system of the present invention is used, as described above, it is not necessary to perform toner cleaning after the toner transfer and before the main charging of the photosensitive member. Therefore, the cleaning mechanism can be saved and the cleaning can be performed. It is also possible to avoid abrasion of the photoconductor, and it is possible to provide a simplified electrophotographic system at a low cost.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining the principle of reversal development.

FIG. 2 is a side layout view showing a simplified layout of an image forming apparatus to which the developing method of the present invention is applied.

FIG. 3 is a layout diagram showing an example of a non-magnetic one-component developing device.

[Explanation of symbols]

 1 Organic Photosensitive Layer 2 Elastic Developing Roller 3 Non-Magnetic One-Component Toner 6 Rotating Photosensitive Drum 11 Main Charging Corona Charger 12 Laser Light Source 13 Image Exposure Optical System 13 Developer 14 Transfer Mechanism 15 Static Eliminating Light Source 16 Transfer Material 20 Development Container 21 Sub-Roller 22 Agitator 23 Development Opening 24 Slit-shaped Opening 25 Toner Storage 26 Toner Supply Roller 27 Blade

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuya Yasui 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Engineering Co., Ltd. (72) Shinichi Higo 1-228 Tamatsukuri, Chuo-ku, Osaka Within Mita Engineering Co., Ltd.

Claims (6)

[Claims] 1. An elastic developing roller coated with a non-magnetic mono-component toner and having a thin layer of the toner formed by regulation by a layer thickness regulating member, and a photoreceptor having an electrostatic latent image formed by charging and exposure. In the developing method for electrophotography, the toner thin layer has a bulk density of 0.35 to 0.55 g / cm ³ and a toner amount in the developing portion is 0.5 to 0.80 mg / cm ² . A developing method in electrophotography, which is characterized in that 2. The toner has a circularity defined by the following formula: circularity = circumferential length of a circle having the same area as projected toner particles / contour length of projected toner particles is 0.94.
2. The spherical toner as described above is used.
The developing method described. 3. The developing method according to claim 1, wherein the non-magnetic one-component toner is a spherical toner produced by a polymerization method. 4. The developing method according to claim 1, wherein an organic photoconductor is used as the photoconductor. 5. The positively chargeable single-layer organic photoreceptor in which the charge generating agent is dispersed in the charge transporting medium.
5. The developing method according to any one of 4 to 4. 6. The charging polarity of the toner and the charging polarity of the dark portion of the photoconductor are set to the same polarity, and the reversal development is performed under a developing condition in which the residual toner on the dark portion of the photoconductor is substantially zero. The developing method according to any one of claims 1 to 5.