JPH0337675A - Image forming method and device thereof - Google Patents

Abstract

PURPOSE:To decrease image defects, such as moire, and photofatigue and to improve durability by executing an image exposing by a digital exposing with <=7erg/cm<2> image exposing energy and using a conductive base having a specific surface roughness as the conductive base of an image carrying member at this time. CONSTITUTION:The surface of the image carrying member 1 is uniformly electrified by a scorotron electrifying electrode 2. The image carrying member 1 is then irradiated thereupon with the image exposing light L from a laser optical system 10, by which an electrostatic latent image is formed. This electrostatic latent image is reversally developed by developing devices 31 to 34 in which toners are housed. The image exposing is executed by the digital exposing with the image exposing energy of <=7erg/cm<2> max. exposing energy as an incident light quantity; in addition, the conductive base having the surface roughness of (0.5-0.01)S Rmax is used as the conductive base 71 of the image carrying member 1. The reflected light from the conductive base 1 is weakened in this way and the image defects, such as moire, and the photofatigue are decreased and the durability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an image forming method and an apparatus therefor. Multicolor image forming device (color copy)
The present invention relates to an image forming method and apparatus suitable for monochrome printers, monochrome printers, and electrophotographic copying machines.

760-800 nm in the conventional multicolor image forming method.
A digital copy or printer is known that performs digital image exposure using light of wavelengths such as 0 to 1, and forms image constituent units in the form of dots.

However, the exposure energy during the above exposure was 7erg/c.
If ta is exceeded (for example, when irradiating with light of 15 erg/crl), the energy is too strong in the case of a photoreceptor with high photosensitivity, and the degree of optical fatigue increases accordingly, and the durability deteriorates. This can be avoided by lowering the exposure energy, but this poses the problem of making it difficult to achieve high sensitivity. Also, if the exposure energy is as large as above,
Moiré tends to occur due to the influence of light reflected from the conductive support under the photosensitive layer, making the image difficult to see.

C.1 Objective of the Invention An object of the present invention is to provide a method and apparatus that can reduce image defects such as moire, reduce optical fatigue, and improve durability.

21 Structure of the Invention That is, the present invention provides an image forming method in which an electrostatic latent image is formed on an image carrier by charging and image exposure, and this electrostatic latent image is visualized, in which the image exposure is performed digitally. Due to exposure (maximum exposure energy as incident light amount) 7erg/c
The image exposure energy is Ia or less, and at this time, Rmax of the conductive support of the image carrier is (0,5-
The present invention relates to an image forming method characterized in that a material having a surface roughness of 0,01) is used.

Further, the present invention provides that RIImX is (0,5-0,01)
A charging means, a digital exposure means having a maximum image exposure energy as an amount of incident light of 1 erg/c4 or less, and a developing means are arranged along an image carrier having a photosensitive layer on a conductive support having a surface roughness of S. The present invention also provides an image forming apparatus in which a.

In addition, in the above, as a light source that provides exposure energy of 7erg/CTM or less, a laser light source, an LED l
In addition to point light sources such as EL (electroluminescence) light sources and line light sources that are arrays of these light sources, it is also possible to use surface light sources such as white light and tungsten light by using liquid crystal shutters, etc. .

First, an example of an image forming apparatus (for example, a digital copying type multicolor image forming apparatus) that can be used in the present invention will be described with reference to FIGS. 1 to 3.

According to this apparatus, as shown in FIG. 2, in the image reading section LE, the original 18 placed on the original table 19 receives light from the illumination light source 13 moving in the X direction, and the reflected light 20 is Pond 14, lens 15 and color separation filter 16
Each CCD image sensor 17R117 for red, green, and blue
G, imaged on the 17th. These CCD image sensors convert optical information into time-series electric signals and send them to an image data processing section TRY (see FIG. 3), where recorded image data is formed. In the laser optical system 10, the laser beam of the semiconductor laser 21 is PWM-modulated in the modulation section MD based on the recorded image data from the video signal processing section TR (in the figure, 22 is a polygon mirror). On the other hand, image carrier 1
The surface is uniformly charged by the scorotron charged electrode 2. Subsequently, the image carrier (photosensitive drum) 1 is irradiated with image exposure light from the laser optical system 10 . In this way, an electrostatic latent image is formed. For example, when a blue filter is set as the color separation filter 16, this electrostatic latent image is reversely developed by a developing device 31 containing yellow toner. The image carrier 1 on which the toner image has been formed is uniformly charged again by the scorotron charging electrode 2, and then, for example, when a green filter is set as the color separation filter 16, the optical information read through this filter is Receives basic image exposure. The formed electrostatic latent image is reversely developed by a developing device 32 containing magenta toner. As a result,
A two-color toner image is formed on the image carrier 1 using yellow toner and magenta toner. Thereafter, the cyan toner and black toner are superimposed and reversely developed in the developing units 33 and 34 in the same manner, and a four-color toner image is formed on the image carrier 1. 4
The color toner image is charged by a pre-transfer charging electrode as necessary and transferred to the recording paper P at the transfer pole 4 at once. Recording paper P is separated from image carrier 1 by separation pole 5 and fixed by fixing device 6 . On the other hand, the image carrier 1 is cleaned by a cleaning device 8.

Although a four-color toner image has been described above, a two-color toner image or a single-color toner image may be formed depending on the case.

According to FIG. 2, the control unit CT is actuated by the operation unit OP, and the image reading unit LE whose operation is controlled by the control unit converts the optical information of the document 18 into time-series signals for each color.
The obtained data is processed in an image data processing section TR, and further converted into data suitable for recording in a video signal processing section TR. The image forming section RE executes the above-described process for forming an image based on the control signal, transfers a toner image onto copy paper, and forms a recorded matter. This image forming section RE employs an electrophotographic method.

In addition to the above, various preset information, especially data on functional operation contents such as the copy magnification and color described above, can be stored in the ROM (Re
ad 0nly Memory), a floppy disk, a magnetic tape, etc., and retrieves the information in the image memory ME as necessary to send it to the image forming section R.
It can be output to E.

In the above-mentioned apparatus, the developing units 31 to 34 have a basic configuration as shown in an enlarged view in FIG. 2. In each of these developing devices, a non-magnetic developing sleeve 41 serving as a developer transport carrier rotates counterclockwise, and an internal magnet body 42 rotates clockwise, so that the developer 50 in the developer reservoir 43 is transferred to the developing sleeve 4.
1 and transported in the opposite direction to the rotation of the magnet body 42. The thickness of the developer conveyed on the developing sleeve 41 is regulated by a layer thickness regulating blade 44 on the way, thereby forming a developer layer.

When developing, a DC bias voltage and/or an AC voltage is applied to the developing sleeve 41 by the bias voltage a52. As a result, development is performed in the development area E,
The developer layer that has passed through the development area E is cleaned by the cleaning blade 4.
The developer is removed from the developing sleeve 41 by the developer reservoir 4
It is reduced to 3.

The developer reservoir 43 is supplied with toner from a toner hopper (none of which is shown) by a toner supply roller.

Further, the developer 5° in the developer reservoir 43 is uniformly stirred by the stirring or conveying means 46, 47, 48, and
A sufficient charge is imparted to the toner particles.

In the above, the developer layer may be conveyed by keeping the developing sleeve 41 stationary or rotating clockwise, or by moving the developing sleeve 41 by rotating the magnetic body 41.
This may be done by rotating to the left or standing still.

Furthermore, although a one-component developer made of magnetic toner particles can be used as the developer 50, a two-component developer made of a mixture of magnetic carrier particles and non-magnetic toner particles is preferable in terms of color clarity and toner charge control. It is preferably used from

The development using the developing device shown in Fig. 2 is preferably carried out by a non-contact development method, but the detailed development conditions are disclosed in Japanese Patent Application Laid-Open No. 57-147.
It may be the same as that described in No. 652 or No. 59-181362 (however, both use a two-component developer). In addition, when using a -component developer,
It may be the same as that described in No. 5-18656 or Japanese Patent Publication No. 41-9475.

During development by the developing units 31 to 34, in order to apply a bias voltage to the developing sleeve 41 to effectively control toner flight, an alternating electric field applied between the image carrier 1 and the developing sleeve 41 must be applied. 100J (z ~ 5KHz,
The DC bias is preferably 100-2 KV. Further, the gap 51 between the image carrier 1 and the developing sleeve 41 is 10 to
2000 μm range, therefore, the layer thickness regulating blade 44
It is preferable that the thickness of the developer layer regulated by the gap be made thinner than the above-mentioned gap.

By using the above-mentioned preferable conditions for the developing units 31 to 34, it is possible to clearly develop electrostatic latent images for each color using each developing unit without fogging. Therefore, a clear monochrome image or a multicolor image is recorded on the recording paper P.

In addition, when the developer 50 is made of two components, the particle diameters of the carrier and toner are preferably 5 to 50 μm for the former and 20 μm or less for the latter. As the carrier, a magnetic carrier or an insulating carrier coated with an insulating material can be used.

When the developer 50 is made of one component, a known insulating toner can be used.

Furthermore, the present invention is of course applicable not only to the above-mentioned apparatus but also to other types of copying machines. Furthermore, the development is not limited to reversal development, and regular development may be used.

The present inventor has developed a semiconductor laser 21 (with a wavelength of 760 to 800 in particular) during digital exposure in the above-mentioned image formation.
7erg/c
+II or less, which is a small range, and the image carrier 1
The surface roughness (R□X) of the conductive support 71 is (0,5-
0,01) It has been found that all of the problems mentioned above can be overcome by using S.

That is, by setting the exposure energy to 7 erg/cffl or less, the reflected light from the conductive support 71 is weakened, moire can be effectively prevented, and the degree of optical fatigue of the photoreceptor can also be suppressed. . In this case, since the surface roughness (R □ There is no problem with this, and moire etc. are greatly reduced. This Rmax is 0
．． Since it is 5S or less, the surface properties of the conductive support 71 are good, the adhesion between it and the photosensitive layer is improved, and the surface potential of the photoreceptor is reduced due to carrier injection from the conductive support →
Image defects such as the occurrence of black spots during reversal development can be prevented (if the IIS exceeds 0.5 μl, the surface irregularities of the conductive support become large, resulting in poor cleanability and image defects).

The above image exposure energy is preferably 6 erg/cffl or less, and Rsix of the conductive support is (0,40
, 01) S is preferable (approximately 0.1 μms is practical). It is difficult to make RlX too small from the viewpoint of processing, and its lower limit should be 0.01 μmS.

When the image exposure energy is reduced as described above, it is necessary to increase the photosensitivity of the photoreceptor, but as mentioned above, increasing the image exposure energy actually increases optical fatigue, so the image exposure energy is 7erg/cffl. It should be: However, due to insufficient light intensity, it is particularly desirable in the present invention to use the following titanyl phthalocyanine as a photoconductive material in the photosensitive layer.

That is, this titanyl phthalocyanine has CuKα property X
The Bragg angle 2θ of the X-ray diffraction spectrum for the line (wavelength 1.541) is at least 9.6 degrees ± 0.2 degrees and 2
It is in a crystalline state with a peak of X-ray intensity at 7.2 degrees ± 0.2 degrees, exhibits high sensitivity to dot exposure with relatively long wavelength light such as semiconductor laser light, and has a high T ( (The optical attenuation characteristic of the charged potential is rapid.) This titanyl phthalocyanine also has a temperature of 9.6 degrees ±
It is desirable that the peak X-ray intensity at 0.2 degrees is 40% or more of the peak X-ray intensity at 27.2 degrees ±0.2 degrees.

By using such titanyl phthalocyanine, a highly sensitive photoreceptor can be obtained, and even with a small exposure amount of 1 erg/cf or less, a sufficient potential drop can be observed, and a sufficient amount of toner adhesion can be obtained. Formed in concentration. In addition, in image formation using dots, high reproducibility of one dot is required, and the titanyl phthalocyanine of the present invention has a suitably high γ (so-called on-off type) to meet this requirement. Because of these characteristics, the reproducibility of dots is good.

The basic structure of the titanyl phthalocyanine of the present invention may be represented by the following general formula.

General 2: In the formula, XI, XI, X3 and X4 each represent a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group, and n, m, i and k each represent an integer of 0 to 4.

The X-ray diffraction spectrum is measured under the following conditions (the same applies below). The peak here refers to a distinct sharp protrusion that is different from noise.

X-ray tube Cu voltage '40. OKV Lightning current 100.0 mA Start angle
6. Odeg.

Stop angle 35. Odeg.

Step angle 0.02 deg.

Measurement time: 0.50 sec.

In addition, the above X and line diffraction spectra were measured using a "320 type self-recording spectrophotometer" (manufactured by Hitachi Seisakusho),
It is considered to be a reflection type diffraction spectrum.

The method for producing the titanyl phthalocyanine will now be described. For example, 1,3-diiminoisoindoline and sulfolane are mixed, titanium tetrapropoxide is added thereto, and the reaction temperature is 80-30°C.
0"C, particularly preferably 100 to 260°C. After the reaction is completed, the precipitate is collected by filtration after being left to cool. Next, by treating this with a solvent, the titanyl phthalocyanine can be obtained. The desired crystalline titanyl phthalocyanine shown in can be obtained.

As the apparatus used for this treatment, in addition to a general stirring apparatus, a homomixer, a disperser agitator, a ball mill, a sand mill, an attritor, etc. can be used.

In the present invention, other carrier-generating substances may be used in combination with the above titanyl phthalocyanine. Such carrier-generating substances include those that differ in crystal form from the titanyl phthalocyanine of the present invention, such as α-type, β-type, α, β
Examples include mixed type, amorphous type, etc. titanyl phthalocyanine, other phthalocyanine pigments, azo pigments, anthraquinone pigments, perylene pigments, polycyclic quinone pigments, squareium pigments, and the like.

Various carrier transport substances can be used in the photoreceptor of the present invention, but representative examples include nitrogen-containing heterocyclic nuclei represented by oxazole, oxadiazole, thiazole, thiadiazole, imidazole, etc. Compounds having such condensed ring nuclei, polyarylalkane compounds, pyrazoline compounds, hydrazone compounds, triarylamine compounds, styryl compounds, styryltriphenylamine compounds, β-phenylstyryltriphenylamine compounds, Examples include butadiene compounds, hexatriene compounds, carbazole compounds, and fused polycyclic compounds. Specific examples of these carrier transport substances include, for example, Japanese Patent Application Laid-Open No. 61-107
Although many materials can be mentioned, including the carrier transport material described in No. 356, the structure of a particularly representative material is shown below.

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (13) CtHs (14) (15) (17) (18) ( 19) (20) Various configurations of photoreceptors are known. Although the photoreceptor of the present invention can take any of these forms, it is preferably a layered or dispersed functionally separated photoreceptor.

In this case, the configuration is usually as shown in FIGS. 4 to 9. The layer structure shown in FIG. 4 is such that a carrier generation layer 72 is formed on a conductive support 71, and a carrier transport layer 73 is laminated thereon to form a photosensitive layer 74. A photosensitive layer 174 is formed in which the carrier generation layer 72 and the carrier transport layer 73 are reversed. FIG. 6 shows an intermediate layer 7 between the photosensitive layer 74 and the conductive support 71 having the layer structure shown in FIG.
In FIG. 7, an intermediate layer 5 is provided between the photosensitive layer 74 and the conductive support 71 having the layer structure shown in FIG. The layer structure shown in FIG. 8 is one in which a photosensitive layer 74 containing a carrier generating substance 76 and a carrier transporting substance 77 is formed, and in FIG. A layer 75 is provided. Further, a protective layer (not shown) may be provided on the outermost surface of the photoreceptor.

In forming the photosensitive layer, it is effective to apply a solution in which a carrier-generating substance or a carrier-transporting substance is dissolved alone or together with a binder or an additive. However, because the solubility of carrier-generating substances is generally low,
In such cases, the carrier-generating material is treated with an ultrasonic disperser,
An effective method is to apply a liquid in which fine particles are dispersed in a suitable dispersion medium using a dispersion device such as a ball mill, sand mill, or homomixer. In this case, the binder and additives are usually added to the dispersion.

A wide variety of solvents or dispersion media can be used to form the photosensitive layer. For example, butylamine, ethylene diamine, N, N dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, ethylene glycol dimethyl ether, toluene, xylene, acetophenone, chloroform, dichloromethane, Examples include dichloroethane, trichloroethane, methanol, ethanol, propanol, butanol, and the like.

When a binder is used to form a carrier generation layer, a carrier transport layer, or a photosensitive layer, any binder can be selected as the binder, but a hydrophobic polymer having a film-forming ability is particularly desirable. Examples of such polymers include, but are not limited to, the following:

Polycarnenate 7) Resin Polyvinyl chloride Polystyrene Polyvinyl acetate Polyvinyl butyral Polycarnenate 2 Jugetsu Methacrylic resin Polyvinyritine chloride Styrene-butadiene copolymer Polyvinyl Honrumal Polyvinyl acecool f Rivinyl carbazole Styrene-Alkit Resin Silicone Jugetsuji Silicone - Full Kit Jugetsuji Polyester
Phenolic resin polyurethane
Epoxy resin Vinyritine chloride-acrylic nitrile copolymer Vinyl chloride-vinyl acetate copolymer Vinyl chloride-vinyl acetate-maleic anhydride copolymer The ratio of the carrier-generating substance to the binder is 10 to 600.
It is preferably 50 to 400 wt%, more preferably 50 to 400 wt%. The ratio of carrier transport substance to binder is 10
It is desirable to set it to 500 wt%. The thickness of the carrier generation layer may be 0.01 to 20 μm, more preferably 0.05 to 5 μm. The thickness of the carrier transport layer may be 1 to 100 μm, more preferably 5 to 30 μm.

The photosensitive layer may contain an electron-accepting substance for the purpose of improving sensitivity, reducing residual potential, or reducing fatigue during repeated use. Examples of such electron-accepting substances include succinic anhydride, maleic anhydride, dibromo succinic anhydride, phthalic anhydride, tetrachlorophthalic anhydride, tetrabromo phthalic anhydride, 3-nitro-phthalic anhydride, and 4-nitro-phthalic anhydride. Acid, pyromellitic anhydride, mellitic anhydride, tetracyanoethylene, tetracyanoquinodimethane, 0-dinitrobenzene, m-dinitrobenzene, 1,3.5-)dinitrobenzene, p-nitrobenzonitrile, vicryl chloride , quinone chlorimide, chloranil, bromanil, dichlordicyano-p-benzoquinone, anthraquinone, dinitroanthraquinone, 9-fluorenylidenemalonodinitrile, polynitro-9-fluorenylidenemalonodinitrile, picric acid, 0-nitrobenzoic acid , p-nitrobenzoic acid, 3゜5-
Examples include dinitrobenzoic acid, pentafluorobenzoic acid, 5-nitrosalicylic acid, 3,5-dinitrosalicylic acid, phthalic acid, mellitic acid, and other compounds with high electron affinity. The addition ratio of the electron-accepting substance is desirably 0.01 to 200, more preferably O11 to 100, based on the weight fi100 of the carrier generating substance.

Further, the photosensitive layer may contain deterioration inhibitors such as antioxidants and light stabilizers for the purpose of improving storage stability, durability, and environmental dependence.

Compounds used for such purposes include, for example, chromanol derivatives such as tocopherol and their etherified or esterified compounds, polyarylalkane compounds, hydroquinone derivatives and their mono- and dietherized compounds, benzophenone derivatives, benzotriazole derivatives, and thioethers. Compounds, phosphonic acid esters, phosphorous acid esters, phenylene diamine derivatives, phenol compounds, hindered phenol compounds, linear amine compounds, cyclic amine compounds, hindered quaternary compounds, and the like are effective. A specific example of a particularly effective compound is rlRGANOX 1010. , rlRGANO
X 565J, (manufactured by Ciba Geigy), ``Sudan Riser BHT'', ``Sutan Riser MDPJ''
Hindered phenol compounds such as (manufactured by Shido Kagaku Kogyo Co., Ltd.), Sanol LS-2626J,
Examples include hindered amine compounds such as -622LDJ (manufactured by Sankyo Co., Ltd.).

As the binder used for the intermediate layer, protective layer, etc., those listed above for the carrier generation layer and carrier transport layer can be used, but in addition, polyamide resin, nylon resin, ethylene-vinyl acetate copolymer, Ethylene-
Ethylene resins such as vinyl acetate-maleic anhydride copolymer and ethylene-vinyl acetate-methacrylic acid copolymer, polyvinyl alcohol, cellulose derivatives, and the like are effective.

As the conductive support 71, a metal plate or a metal drum may be used, or a thin layer of a conductive polymer, a conductive compound such as indium oxide, or a metal such as aluminum or palladium may be coated, vapor-deposited, or coated with a thin layer of metal such as aluminum or palladium. Depending on the means, it is possible to use one provided on a substrate such as paper or plastic film.

E. Example (Synthesis Example 1) 1.29.2 g of 3-diiso-4-fudrin and 200 mj of sulfolane! 17.0 g of titanium tetraisopropoxide was added, and the mixture was heated at 140°C under a nitrogen atmosphere.
The mixture was allowed to react for 2 hours. After cooling, the precipitate was collected by filtration, washed with chloroform, washed with a 2% aqueous hydrochloric acid solution, washed with water, washed with methanol, and dried.
%) of titanyl phthalocyanine was obtained.

This product was dissolved in 20 times the amount of concentrated sulfuric acid, poured into 100 times the amount of water to precipitate it, collected by filtration, and the wet cake was heated with 1,2-dichloroethane at 50°C for 10 hours. A crystal form having an X-ray diffraction spectrum shown in FIG. 10 was obtained. In this crystal, the peak intensity at a Bragg angle of 2θ of 9.6 degrees was 102% of that at 27.2 degrees.

3 parts of titanyl phthalocyanine having the X-ray diffraction pattern shown in Figure 10 obtained in Example 1, 15% xylene-butanol solution of silicone resin CrKR-5240 as a binder resin (manufactured by Shin-Etsu Chemical Co., Ltd.) 35 parts and 100 parts of methyl ethyl ketone as a dispersion medium were dispersed using a sand bowl, and this was coated by dip coating on a drum drum coated with a 0.3 μ thick polyamide resin layer to obtain a film thickness of 0.2 μm. A carrier generation layer was formed. Next, 1 part of carrier transport substance (2), 1.3 parts of polycarbonate resin "Nipiron Z200J (manufactured by Mitsubishi Gas Chemical Co., Ltd.)" and a trace amount of silicone oil rKF-54J were added.
(manufactured by Shin-Etsu Chemical Co., Ltd.) dissolved in 10 parts of 1,2-dichloroethane was applied using a blade coater, and after drying,
A carrier transport layer with a thickness of 20 μm was formed. The photoreceptor thus obtained is referred to as sample 1. In addition, a sheet sample was also prepared by applying the above photosensitive layer onto a polyester base coated with aluminum using a wire bar.

Note that the spectral sensitivity distribution of the photoreceptor of this sample 1 is the 11th
As shown in the figure, the long wavelength sensitivity was particularly good.

Note that the spectral sensitivity (Sλ) shown in FIG. 11 is defined as follows. That is, this is the amount of light necessary to expose the sample to monochromatic light having a wavelength of λ until the acceptance potential of 800 square meters falls to 400 square meters, and the exposure intensity at this time was defined as 0.5 uW/aA. The exposure amount E (μJ/c+fl) is the product of the exposure intensity and the exposure time (L (sec)) at this time. Also,
The dark decay (DD) at 800V is the amount of potential drop when the same photoreceptor is left unexposed for a time t sec after being charged at 800V. The spectral sensitivity Sλ was defined by the following formula.

In place of the titanyl phthalocyanine in Example 1, a known τ-type metal-free phthalocyanine (Japanese Patent Application Laid-Open No. 18263-1983) was used.
A photoreceptor (sample 2) was obtained in the same manner using a photoreceptor (see No. 9).

As shown in FIG. 12, the X-ray diffraction spectrum of the phthalocyanine of Example 2 shows that the Bragg angles of CuKα (containing 1,541) with respect to the X-ray are 7.6 degrees, 9.2 degrees, and 16 degrees.
It has peaks at 8 degrees, 17.4 degrees, 20.4 degrees, and 20.9 degrees. In addition, in the infrared absorption spectrum, 700 to 7
Between 60C11, there are four absorption bands with the strongest strength at 752 part 2cm-', two absorption bands of almost equal strength between 1320 and 1340C[D-', and an absorption band characteristic of 3288±2c'1. There is.

(Evaluation) The sample for the above sheet was used as EPA-810 manufactured by Rodenki Co., Ltd.
When the surface potential was evaluated as 0 and the change in surface potential with respect to exposure energy was measured, the results were as shown in FIG. (V)
l is the charging potential, VL is the potential after exposure). It can be seen that the photoreceptor of sample 1 exhibits high sensitivity. From the results in Figure 13,
Exposure energy is 7 erg/cIi1 or more, for example 1
When irradiated with light of 5 erg/cffl, the apparent energy received by a normal photoreceptor is three times greater, since a photoreceptor using titanyl phthalocyanine has three times better sensitivity than a normal photoreceptor. In other words, since it receives light that is three times stronger, the degree of optical fatigue increases and its durability decreases accordingly.

Also, moire tends to appear when the light is strong.

However, this can be effectively prevented by controlling the exposure energy to 1 erg/ci or less based on the present invention.

Next, using the above-mentioned drum-shaped photoreceptor, durability evaluation of 10,000 copies was conducted.

7erg/cffl, 9erg/C111〆Vl'li
! /d, and the conductive support was 0.005 μm and 0.01 μm in Rff1ax.
, 0.03 μm, 0.4 μm, 0.5 μm,
Evaluation was performed using AN drums of 0.6 μm and 1.2 μm (however, V) l = -600V, VDC bias -5
00■). The results are shown in the table below.

Evaluation of black spots and moire was performed based on the following criteria.

Practical level 11 soil-1 〇 Within 10 pieces of 0.1 mmφ or less, 0.1 mmφ and 20.5 mmφ or less Moiré of 10 or more: ◎ None at all (halftone image, solid black image) Some presence only in halftone image, no solid black Both halftone and solid black have quite strong moiré (margin below) Table From this result, Ramx is large, Good images were obtained with low exposure energy.

Next, photoreceptor samples 1 and 2 were evaluated for printing durability 10,000 times. The results are shown in Table 2 below. The evaluation machine used was a Lips-10 (manufactured by Konica) reversing and modified machine.

Table-2 From this result, under the conditions of the present invention, ■□, ■.

It can be seen that there is little change in

Effects of the Invention As described above, the present invention improves the surface roughness of the conductive support @0.01#-0,5/'/)S(R,
, , ), and the exposure amount is 7 erg/cffl or less, it is possible to obtain an image with high sensitivity, less repeated optical fatigue, and fewer image defects such as black spots and moire.

This is particularly noticeable when titanyl phthalocyanine is used in the photoreceptor.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a schematic sectional view of a copying machine, Fig. 2 is a sectional view of essential parts of a developing device, Fig. 3 is a block diagram of a copying operation, and Fig. 4 , FIG. 5, FIG. 6, FIG. 7, FIG. 8, and FIG. 9 are cross-sectional views showing specific examples of the layer structure of the photoreceptor used in the present invention, and FIG. 10 is obtained by Synthesis Example 1. Each X-ray diffraction diagram of titanyl phthalocyanine, Figure 11 is the spectral sensitivity distribution diagram of titanyl phthalocyanine, Figure 12 is the X-ray diffraction diagram of τ-type metal-free phthalocyanine, and Figure 13 is the surface potential change during exposure of the photoreceptor. This is a graph showing. In addition, in the symbols shown in the drawings, 1...Photoreceptor 2...Charger 4...Transfer pole 5... ...Separation electrode 6 ...Fuser 8 ...Cleaning device 10 ...
...Laser optical system 17R, 17G, 17B...
...... CCD image sensor 18 ...... Original 21 ...... Semiconductor laser 31.32.3
3.34...Developer 41...
...Development sleeve 42...Magnet body 43...Developer reservoir 44...Layer thickness regulation plate 61...
...Digital data output device 62...
...D/A converter 63...Triangle wave generation circuit 64...Comparator 65...Horizontal synchronization signal generation circuit 67...
......Timing signal generation circuit 68...
...Raster scan 1971 part 71...
Conductive support 72...Carrier generation layer 73...
...Carrier transport layer 74.74.74...
. . . Photosensitive layer 75 . . . Intermediate layer L . . . Image exposure E . . . Development area.

Claims (1)

[Scope of Claims] 1. In an image forming method in which an electrostatic latent image is formed on an image carrier by charging and image exposure, and this electrostatic latent image is visualized, the image exposure is performed by digital exposure. /cm^
The image exposure energy is 2 or less, and at this time, R_m_a_x as the conductive support of the image carrier is (0.
5-0.01) An image forming method characterized by using a material having a surface roughness of S. 2. A charging means and an image exposure energy of 7 erg/cm were installed along the image carrier, which is a conductive support having a surface roughness of R_m_a_x of (0.5-0.01)S and a photosensitive layer provided thereon.
An image forming apparatus in which a digital exposure means of ^2 or less and a developing means are arranged.