JPH0689036A - Image forming device - Google Patents

Abstract

PURPOSE:To embody such an image forming device capable of obtaining a picture image having good reproducibility of gradation in high-light area of the image. CONSTITUTION:The electrophotograhic sensitive body has a photosensitive layer or both of a photosensitive layer and protective layer on a conductive supporting body. The surface of the photosensitive body has 10-point average surface roughness between >=0.1mum and <=5.0mum. The image forming device has an electrostatic image forming means to form an electrostatic latent image on the electrophotographic sensitive body with a laser beam. The laser beam gives 3X10<-3>mm<2> or smaller spot size on the photosensitive body. The obtd. image has good reproducibility of gradation in a high-light area in the image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, among image forming apparatuses, a laser printer is well known in which a photoconductor is imagewise exposed with a laser and is developed to obtain an image. This laser printer has advantages such as high printing quality and high printing speed, and is widely known as an output device such as a personal computer and a word processor.

FIG. 2 is a block diagram of an image forming portion of a conventional laser printer.

In FIG. 2, at the start of printing, the photosensitive member 1 starts rotating in the direction of arrow 2. At the same time, the pre-exposure lamp 13 is turned on to remove the residual charges on the photoconductor 1 and uniformly charged by the charger 3. The above operation is continued for one rotation of the photoconductor 1 (hereinafter referred to as pre-rotation). This pre-rotation prevents the chargeability and the sensitivity of the photoconductor 1 from becoming unstable due to the history of the photoconductor 1 before the start of printing.

Thereafter, irradiation of pre-exposure 13 and uniform charging by the charger 3 are performed, and laser light from the semiconductor laser 4 driven according to the image data 21 output by the image processing unit 20 is applied to the surface of the photoconductor. Image exposure is performed by image scanning exposure that exposes the image area and does not expose the non-image area, and an electrostatic latent image is formed on the photoreceptor.

This latent image is developed by the developing device 5, and a toner image is formed on the photoconductor 1. This image is a transfer charger 6
After being transferred to and transferred to 7 and electrostatically separated by a separation charging device 8, it is fixed by a fixing device 9 and discharged. The transfer residual toner remaining on the photoconductor 1 is cleaned by the cleaner 10.

The photoconductor is required to have predetermined sensitivity, electrical characteristics and optical characteristics according to the electrophotographic process as described above. The surface layer of the photoconductor, that is, the layer most distant from the support, is directly applied with an external electric or mechanical force such as corona charging, toner development, transfer to paper, and cleaning treatment, so that durability against them is high. Required.

Various methods have been studied in order to satisfy the properties required for such a surface layer. However, a means of using a system in which a fluorine resin is dispersed in a thermoplastic resin or a curable resin is used in the surface layer. It is effective. As the curable resin, thermosetting resins such as polyurethane resin, epoxy resin, melamine resin, or guanamine resin, and photocurable resins typified by polyacrylates are used.

However, when the above-mentioned resin is used as the surface layer of the photosensitive drum, spray coating or dip coating is carried out, but the surface roughness after coating is often rough, and depending on the resin, it may be lower than the initial durability. The average surface roughness value is 0.5 μm to 3.
It may be 0 μm.

In a system in which a fluorocarbon resin is dispersed in a thermoplastic resin, in order to bring out the initial surface lubricity, the fluorocarbon resin wrapped in the thermoplastic resin is exposed on the surface after coating and drying. Therefore, the surface layer may be polished. The average surface roughness value at this time is 0.1 μm to 5.0 μm.
It becomes m.

On the other hand, the most common blade cleaning method in the cleaning process for removing the residual toner is always accompanied by the problem of blade reversal. this is,
This is a problem that occurs because the frictional force between the photoreceptor surface and the bleed is very high, and blade reversal occurs when a certain threshold is exceeded. On the other hand, in addition to containing a lubricant such as a fluororesin in the surface layer as described above to reduce the frictional force on the surface of the photoconductor, the surface layer itself is roughened to reduce the frictional force. Means have been proposed. Also in this case,
The average surface roughness value is 0.1 μm to 5.0 μm.

[0012]

In the conventional example, as described above, the average surface roughness value of the photosensitive layer on the conductive support or the surface layer of the electrophotographic photosensitive member having the photosensitive layer and the protective layer is JIS. The 10-point average roughness defined by the standard B061 may be 0.1 (μm) or more and 5.0 (μm) or less due to various factors. Conventionally, when such an electrophotographic photosensitive member is used in an image forming apparatus using a laser beam such as a laser printer, there is a problem that it is difficult to reproduce a highlight portion in image gradation. In particular, in a device that visualizes and superimposes a plurality of electrostatic images to form a color image, a solid image such as a photograph is often printed, and when the above-mentioned photoconductor is used, poor reproduction of highlight portions is very noticeable. There was a problem. The present invention has been made in order to solve the above-mentioned problems, and it is a surface layer of an electrophotographic photoreceptor having a photosensitive layer or a photosensitive layer and a protective layer on a conductive support.
The point average surface roughness is defined by JIS standard B061 10
In an image forming apparatus having an electrostatic forming means for forming an electrostatic latent image on a surface of an electrophotographic photosensitive member having a point average surface roughness of 0.1 (μm) or more and 5.0 (μm) or less, By using the image forming apparatus characterized in that the size of the laser beam spot on the surface of the photoconductor is 3.0 × 10 ⁻³ (mm ² ) or less, in the image gradation, the highlight portion can be sharpened. It was designed to be reproducible.

[0013]

According to the present invention, the 10-point average surface roughness of the surface of an electrophotographic photosensitive member having a photosensitive layer or a photosensitive layer and a protective layer on a conductive support has a JIS B0 standard.
The ten-point average surface roughness defined by 61 is 0.1 (μm) or more and 5.0 (μm) or less, and a static latent image is formed on the surface of the electrophotographic photosensitive member by using a laser beam. In the image forming apparatus having a charge forming unit, the size of the laser beam spot on the surface of the photoconductor is 3.0 × 10 ⁻³ (mm
² ) The following aims to solve the above problems and achieve the above object.

The present inventors consider the factors that may cause the above phenomenon as follows. The poor reproduction of the highlight portion on the image is caused by the scattering of the laser beam on the outermost surface portion of the surface layer, which makes it impossible to form a desired dot on the surface of the photosensitive member and the latent image is disturbed. Therefore, in order to reduce the scattering of the laser light scattered at the outermost surface, it was considered necessary to make the beam diameter smaller and minimize the area change of the spot diameter due to scattering. However, the above consideration is not the reason why the reproduction failure occurs only in the highlight part in the digital copying machine which finds gradation by pulse width modulation, and the reason has not been clarified yet. Therefore, the present invention has empirically found a value satisfying the purpose after repeated trials, and thus it is possible to complete an image forming apparatus capable of clearly reproducing a highlight portion in image gradation. It was

The present invention will be described in detail below.

When the electrophotographic photosensitive member used in the present invention is manufactured, the conductive support is a conductive material in which conductive particles are dispersed in an appropriate binder resin on a support such as metal such as aluminum and stainless steel, paper, plastic or the like. A cylindrical cylinder provided with layers or a film is used. However, when the support itself is conductive, the conductive support need not be provided with a conductive layer. An undercoat layer (adhesive layer) having a barrier function and an undercoat function can be provided on these conductive supports. The undercoat layer improves adhesion of the photosensitive layer, coatability, protection of the conductive support, coating of defects on the conductive support, improvement of charge injection from the conductive support, and electrical property of the photosensitive layer. It is formed for protection against destruction and the like. As the material of the undercoat layer, polyvinyl alcohol, poly-N
-Vinyl imidazole, polyethylene oxide, ethyl cellulose, methyl cell source, ethylene-acrylic acid copolymer, casein, polyamide copolymerized nylon, glue, gelatin and the like are known. These are dissolved in a suitable solvent and coated on a support. The film thickness is about 0.2 μm to 2 μm. As the charge generating material, a cyanine dye, an azulene dye, a squarylium dye, a pyrylium dye, a thiapyrylium dye, a phthalocyanine pigment, an anthranthron pigment,
Azo pigments such as dibenzpyrenequinone pigments, pyranthrone pigments, monoazo pigments, disazo pigments and trisazo pigments, indigo pigments, quinacridone pigments, asymmetric quinocyanines and quinocyanines can be used. As the charge transport material, pyrene, N-ethylcarbazole, N-isopropylcarbazole, N-methyl-
N-phenylhydrazino-3-methylidene-9-ethylcarbazole, 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-N-α-naphthyl-N-phenylhydrazone, p-pyrrolidinobenzaldehyde-N, N-diphenylhydrazone, 1,3,3-
Trimethylindolenine-ω-aldehyde-N, N-diphenylhydrazone, p-diethylbenzaldehyde-
Hydrazones such as 3-methylbenzthiazolinone-2-hydrazone, 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1-phenyl-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [quinolyl (2)]-3- (p-diethylaminostyryl) -5-
(P-Diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3- (p-diethylaminostyryl)
-5- (p-diethylaminophenyl) pyrazoline, 1
-[6-Methoxypyridyl (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [pyridyl (3)]-3- (p-
Diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1- [lepidyl (2)]-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-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline, 1-phenyl-3- (p-diethylaminostyryl) -4-methyl-5- ( Pyrazolines such as p-diethylaminophenyl) pyrazoline, 1-phenyl-3- (α-benzyl-p-diethylaminostyryl) -5- (p-diethylaminophenyl) pyrazoline and spiropyrazolin, 2- (p-diethylaminostyryl) -6 -Diethylaminobenzoxazole, 2-
Oxazole-based compounds such as (p-diethylaminophenyl) -4- (p-dimethylaminophenyl) -5- (2-chlorophenyl) oxazole, and thiazole-based compounds such as 2- (p-diethylaminostyryl) -6-diethylaminobenzthiazole , Bis (4-diethylamino-2-methylphenyl) phenylmethane and other triarylmethane compounds, 1,1-bis (4-N, N-
Diethylamino-2-methylphenyl) heptane, 1,
Polyarylalkanes such as 1,2,2-tetrakis (4-N, N-dimethylamino-2-methylphenyl) ethane, 5- (4-diphenylaminobenzylidene)-
A stilbene compound such as 5H dibenzo [a, d] cycloheptene or 1,2-benzo-3- (d-phenylstyryl) -9-n-butylcarbazole can be used.

The method for preparing the electrophotographic photosensitive member of the present invention will be described by taking the case of a function-separated type photosensitive member in which a charge transport layer is laminated on a charge generating layer as an example.

A homogenizer, ultrasonic wave, and the above charge generating material are used together with a binder resin and a solvent in an amount of 0.3 to 10 times.
Disperse well by methods such as ball mill, vibration ball mill, sand mill, attritor, and roll mill. This dispersion was coated on the support coated with the subbing layer, dried, and then dried.
A coating film of about 1 to 1 μm is formed. Next, a solution of the charge transport material and the binder resin is added to prepare a desired charge transport layer liquid.

The mixing ratio of the charge transport material and the binder resin is about 2: 1 to 1: 4.

As the solvent, aromatic hydrocarbons such as toluene and xylene, chlorine-based hydrocarbons such as dichloromethane, chlorobenzene, chloroform and carbon tetrachloride are used. When applying this solution, for example, a coating method such as a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, or a Curtin coating method can be used, and the solution is coated on the charge generation layer. Post-drying is 10 to 200 ° C, preferably 20 to 150 ° C
Can be carried out at a temperature in the range of 5 minutes to 5 hours, preferably 10 minutes to 2 hours under blast drying or static drying. The formed charge transport layer has a thickness of about 10 to 30 μm.

Further, in the case of a photoreceptor in which the charge generation layer is coated on the charge transport layer, the charge generation layer serves as the surface layer.

This charge generation layer dispersion can be prepared by dispersing the charge generation material in the binder resin used for the charge generation layer, and the dispersion is applied onto the charge transport layer to obtain the present invention. The photoreceptor to be used can be obtained.

When the photosensitive layer has a protective layer, the protective layer becomes the surface layer of the photoreceptor. The resin forming the protective layer is a thermosetting resin such as a polyurethane resin, an epoxy resin, a melamine resin, or a guanamine resin as described above, and a photocurable resin represented by an epoxy resin or a polyacrylate. For example, thermoplastic resins such as polyamide and polycarbonate are used.

Since these resins have very high volume resistance, when they are used alone, the residual potential is large. Therefore, there is a case where a method of mixing conductive metal powder into the layer is adopted. is there. The conductive metal powder applied is metal such as aluminum, copper, nickel, silver, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, tin-doped indium oxide, antimony-doped Metal oxides such as tin oxide and zirconium oxide, and one or more metal oxides selected as appropriate from them, and the primary particles are preferably 0.3 μm or less. The content of the conductive metal powder dispersed in the surface layer is appropriately 5 to 90% by weight, and particularly preferably 10 to 90% by weight, based on the solid weight of the surface layer. If the content is less than 5% by weight, the resistance value is too high and the residual potential becomes high. On the other hand, if it exceeds 90% by weight, the resistance of the surface layer is too low, resulting in a decrease in charging ability and pinholes.

Further, a method has been proposed in which a charge transport material is added to the surface layer for the purpose of moving carriers instead of the above-mentioned conductive metal powder.

On the other hand, many systems in which a fluorine resin is dispersed in the above-mentioned curable resin or thermoplastic resin have been proposed.
This is intended to find surface lubricity.
Examples of the fluorine-based resin powder include tetrafluoroethylene resin, trifluorochloroethylene resin, hexafluoroethylenepropylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodichloroethylene resin, and a mixture thereof. It is appropriately selected from one or two or more kinds of powders selected from polymers, and the molecular weight of the resin, the particle size of the powder and the like are also appropriately selected according to the use of the surface layer to be used.

As a dispersion method of the above-mentioned fluorine-based resin powder, conductive metal powder or charge transport material, a general dispersion means,
That is, a homogenizer, an ultrasonic wave, a ball mill, a vibrating ball mill, a sand mill, an attritor, a roll mill or the like can be used.

The coating may be carried out by a dipping coating method, a spray coating method, a spinner coating method, a bead coating method, a Mayer bar coating method, a blade coating method, a roller coating method or a curtain coating method. it can.

Drying is preferably carried out by drying by touching at room temperature and then drying by heating. Heat drying at 30 ~ 200 ℃ 5
It can be static or blown for a time in the range of minutes to 2 hours.

In the present invention, the diameter of the laser beam is narrowed down and the size of the laser beam spot on the surface of the photoconductor is set to 3 ×.
The following method was used in order to make it 10 ⁻³ (mm ² ) or less.

By using InGaAsP for the semiconductor laser, the wavelength of the laser light was shortened, the diffraction power was reduced, the beam waist was narrowed, and the beam diameter on the drum surface was reduced.

By controlling the laser light diverged from the laser oscillator from parallel light to divergent light convergent light with a variable focus lens, the beam waist of the laser is accurately aligned on the drum surface, and the beam is blurred on the drum surface. Instead, the beam diameter on the drum surface was reduced. Hereinafter, the present invention will be described in more detail with reference to specific examples.

[0033]

【Example】

(Embodiment 1) FIG. 2 is a configuration diagram of a laser beam printer. In the figure, the same reference numerals as those in the conventional example indicate the same or corresponding portions, and duplicate description thereof will be omitted.

In FIG. 2, 20 is an image processing unit,
The digital image data 22 and the reference clock signal 23 are input, and the binarized image data 21 pulse-width modulated almost continuously according to the image density is output. Binary image data 2
1 is input to the laser drive unit 24 to drive the laser 4 and output as modulated laser light. Laser 4
The laser light scans the photoconductor 1, and a two-dimensional electrostatic latent image is obtained as the photoconductor 1 uniformly charged rotates in the direction of arrow 2. Next, the electrostatic latent image is visualized by the developing device 5 and transferred onto the transfer paper 7. The toner remaining without being transferred is collected by the cleaner 10. After the transfer, the transfer paper 7 is separated from the photosensitive drum 1, passes through the fixing device 9, and is discharged.

Reference numeral 25 denotes an electric potential sensor, which is arranged near the surface of the photoconductor 1 at the position after the laser beam exposure of the photoconductor 1 and detects the potential of the electrostatic latent image on the surface of the photoconductor 1. To do. The output of the potential sensor 25 is input to the potential measuring unit 26 and the potential is measured. Since the measured potential is an analog value, it is converted into a digital signal by the A / D converter 27 and input to the control unit 28.

Numeral 29 is a high voltage controller for controlling the charging current of the charger 3, and numeral 30 is a high voltage controller for the grid bias voltage for controlling the grid bias voltage of the charger 3. 24
Reference numeral 31 is a laser driving unit that drives the laser 4 and controls the intensity of the laser light, and 31 is a developing bias voltage control unit that controls the developing bias voltage of the developing device 5.

FIG. 1 shows a model diagram of an optical system around the laser. In the configuration shown in FIG. 1, the optical scanning operation is as follows.

The divergent light modulated from the laser oscillator 41 (InGaAsP semiconductor laser wavelength 675 nm) according to the scanning information is collimated by the collimator lens to be collimated light, divergent light or converged light and propagated to the cylindrical lens 43. Only in the scanning direction, light is condensed on the reflecting surface of the optical deflector, that is, the rotary polygon mirror 44, and irradiated with substantially parallel light as it is in the scanning direction. The laser beam luminous flux reflected by the polygon mirror is scanned by the scanning lens 45. It is refracted again and forms a beam waist on the surface 46 to be irradiated, that is, on the surface of the photoconductor. At this time, the size of the laser beam spot on the surface of the photoconductor is 3.0 × 10.
^{It was -3} (mm ² ) or less.

The method for producing the photoreceptor of the present invention will be described below.

50 parts by weight of conductive titanium oxide powder coated with tin oxide containing 10% antimony oxide, 25 parts by weight of phenol resin, 20 parts by weight of methyl cellosolve, 5 parts by weight of methanol and silicone oil (polydimethylsiloxane poly). 0.002 parts by weight of the oxyalkylene copolymer (number average molecular weight 3000) was dispersed for 2 hours with a sand mill using φ1 mm glass beads to prepare a conductive coating material. Aluminum cylinder (φ80mm x 360)
Dip-coat the above paint on the top, and at 140 ℃ for 30
It was dried for a minute to form a conductive layer having a film thickness of 20 μm.

Next, 30 parts by weight of methoxymethylated nylon resin (number average molecular weight 32000) and 10 parts by weight of alcohol-soluble copolymerized nylon resin (number average molecular weight 29000) were mixed in a mixed solvent of 260 parts by weight of methanol and 40 parts by weight of butanol. The dissolved liquid was applied onto the conductive layer by a dipping coating machine to form an undercoat layer having a film thickness after drying of 1 μm.

Next, a disazo pigment represented by the following structural formula [1]

[0043]

[Chemical 1] 4 parts by weight, 2 parts by weight of benzal resin, and 40 parts by weight of tetrahydrofuran were dispersed for 60 hours in a sand mill using φ1 mm glass beads, and then diluted with a cyclohexanone / tetrahydrofuran mixed solvent to prepare a charge generation layer coating material.

This coating solution was applied onto the above-mentioned undercoat layer by a dipping coating machine to form a charge generation layer having a thickness of 0.1 μm after drying.

Next, the following structural formula [2]

[0046]

[Chemical 2] 10 parts by weight of the charge-transporting material and 10 parts by weight of a polycarbonate resin (number average molecular weight 25000) are dissolved in a mixed solvent of 20 parts by weight of dichloromethane and 40 parts by weight of monochlorobenzene, and this solution is dip-coated on the charge generation layer. Then, it was dried at 120 ° C. for 60 minutes to form a charge transport layer having a film thickness of 20 μm.

Next, 6 parts by weight of a polycarbonate resin (number average molecular weight 25,000), 3 parts by weight of the above charge transport material, polytetrafluoroethylene (average primary particle size 0.3 μm)
1 part by weight is dissolved in a mixed solvent of 200 parts by weight of dichloromethane and 300 parts by weight of monochlorobenzene, and this solution is spray coated on the charge transport layer and dried at 120 ° C. for 60 minutes to form a surface protective layer having a thickness of 5 μm. Formed. Further, in order to express the surface lubricity, the surface of the photoconductor was polished with a lapping film (Fuji Film: Abrasive particles SiC: Abrasive particle size # 2000) for 3 minutes, and the average surface roughness value was JIS standard. The 10-point average roughness defined by B061 was 1.0 μm.

The electrophotographic photosensitive member thus manufactured was subjected to image formation and evaluation by a laser beam printer having the above-mentioned structure. As a result, the highlight part could be reproduced clearly in the image gradation.

(Example 2) The surface protective layer of the electrophotographic photosensitive member of Example 1 was not provided, and the polytetrafluoroethylene particles (average primary particle size 0.3 µm) were 10 in the charge transport layer.
%, A sample was prepared under the same conditions as in Example 1 except that the content was%. At this time, the average surface roughness value of the surface layer was 0.3 μm in terms of 10-point average surface roughness defined by JIS standard B061, and this image forming evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 3 A sample was prepared under the same conditions as in Example 1 except that the polytetrafluoroethylene particles were not contained in the charge transport layer of the electrophotographic photosensitive member of Example 2. . At this time, the average surface roughness value of the surface layer was 0.1 μm in terms of 10-point average surface roughness defined by JIS standard B061, and this image formation evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

Example 4 A sample was prepared under the same conditions as in Example 1 except that the surface of the charge transport layer was not polished in the electrophotographic photosensitive member of Example 3. At this time, the average surface roughness value of the surface layer was 0.05 μm in terms of 10-point average surface roughness defined by JIS standard B061, and this image formation evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Embodiment 5) In the electrophotographic photosensitive member of Embodiment 1, the surface of the surface protective layer is ground by the lapping film of # 800, whereby the surface layer of JIS B
A sample was prepared under the same conditions as in Example 1 except that the 10-point average surface roughness defined by 061 was 5.0 μm. This image output evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 6) The electrophotographic photosensitive member produced in Example 4 was subjected to idle rotation durability, and the surface layer had a 10-point average surface roughness defined by JIS B061 of 2.5 µm.
Then, the image forming evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 7) The electrophotographic photosensitive member produced in Example 4 was subjected to idle rotation durability, and the surface layer had a 10-point average surface roughness defined by JIS B061 of 4.5 µm.
Then, the same image output evaluation as in Example 1 was performed. The results are shown in Table 1.

(Comparative Example 1) The laser oscillator in Example 1 was AlGaAs (wavelength 780 nm), and the size of the laser beam spot on the surface of the photoconductor was 4.3 × 10 ^-3.
Image output was evaluated under the same conditions as in Example 1 except that the thickness was (mm ² ). The results are shown in Table 2.

(Comparative Example 2) The laser oscillator in Example 4 was AlGaAs (wavelength 780 nm), and the size of the laser beam spot on the surface of the photoconductor was 4.3 × 10 ^-3.
Image output was evaluated under the same conditions as in Example 1 except that the thickness was (mm ² ). The results are shown in Table 2.

(Comparative Example 3) The laser oscillator in Example 4 was AlGaAs (wavelength 780 nm), and there was no focus lens on the laser peripheral optical system, and the size of the laser beam spot on the drum surface was 5.8 × 10 ^{−. 3} (mm
Image formation was evaluated under the same conditions as in Example 1 except that ² ). The results are shown in Table 2.

(Comparative Example 4) In the electrophotographic photosensitive member of Example 1, the surface protection of the surface protective layer was carried out by the lapping film of # 800, whereby the JIS standard B of the surface layer was obtained.
A sample was prepared under the same conditions as in Example 1 except that the 10-point average surface roughness defined by 061 was 5.5 μm. This image output evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

As described above, the 10-point average surface roughness of the surface of the electrophotographic photoreceptor having the photosensitive layer or the photosensitive layer and the protective layer on the conductive support is 10 points defined by JIS standard B061. Average surface roughness of 0.1 (μm) or more 5.
In an image forming apparatus having an electrostatic forming means for forming an electrostatic latent image on the surface of an electrophotographic photosensitive member of 0 (μm) or less by using a laser beam, the size of the laser beam spot on the surface of the photosensitive member is 3.0 ×. By setting it to 10 ⁻³ (mm ² ) or less, it is possible to obtain an image with excellent reproduction of the highlight portion on the image in terms of gradation.

[Brief description of drawings]

FIG. 1 is a model diagram of a laser and an optical system around the laser.

FIG. 2 is a configuration diagram of a laser beam printer.

[Description of Reference Signs] 1 Photosensitive drum 20 Image processing unit 24 Laser driving unit 26 Potential measuring unit 28 Control unit 29 High voltage control unit 30 High voltage control unit 31 Development bias control unit 41 Laser oscillator 42a Collimator lens 42b Collimator lens (focus lens) 43 Cylindrical lens 44 Rotating polygonal mirror 45 Scanning lens 46 Irradiated surface (photoreceptor surface)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaaki Yamagami 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tatsuya Ikezue 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Issei Nakamura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (2)

[Claims] 1. A 10-point average surface roughness of a surface of an electrophotographic photosensitive member having a photosensitive layer or a photosensitive layer and a protective layer on a conductive support is 0.1 μm or more and 5.0 μm or less, and the electrophotography In an image forming apparatus having an electrostatic forming means for forming an electrostatic latent image on the surface of a photoconductor using a laser beam, the size of the laser beam spot on the surface of the photoconductor is 3.0 × 10 ⁻³ mm ² or less. An image forming apparatus characterized in that there is. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is an apparatus that forms a color image by visualizing and superimposing a plurality of electrostatic images.