JP2002303997A - Electrophotographic apparatus, process cartridge and electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic apparatus less liable to produce a density difference independently of the light emitting state of laser beams even when a multi-beam system exposure means is used and a de-electrifying means such as pre-exposure is not used and less liable to cause ghosting and a potential change due to repeated use and to provide a process cartridge. SOLUTION: In the electrophotographic apparatus having an electrophotographic photoreceptor having a photosensitive layer on a substrate, an electrifying means, a multi-beam system exposure means to form an electrostatic latent image on the electrophotographic photoreceptor using laser beams, a developing means and a transfer means and not having a de-electrifying means to uniformly de-electrify the electrostatic latent image on the electrophotographic photoreceptor before the electrifying means, the photosensitive layer of the electrophotographic photoreceptor contains oxy-titanium phthalocyanine and the electric charge mobility of the electrophotographic photoreceptor is 7.0×10<-7> -2.0×10<-5> cm<2> /V×s.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an electrophotographic apparatus and a process cartridge.

[0002]

2. Description of the Related Art In recent years, electrophotographic photosensitive members containing various organic photoconductive compounds as main components have been actively developed.
For example, U.S. Pat. No. 3,838,851 describes an electrophotographic photoreceptor having a charge transport layer containing triarylpyrazoline.

Further, US Pat. No. 3,871,880 describes an electrophotographic photoreceptor containing a charge generation layer composed of a perylene pigment derivative and a charge transport layer composed of a condensation product of 3-propylene and formaldehyde. .

[0004] Organic photoconductive compounds have different wavelength ranges of sensitivity depending on the compound.
JP-A-2754 and JP-A-56-167759 disclose compounds having high sensitivity in the visible region.

Further, JP-A-57-195767 and JP-A-61-228453 disclose compounds having high sensitivity in the infrared region.

[0006] Among these compounds, those having sensitivity in the infrared region are used for laser beam printers, digital copiers and LED printers, and the demand for these compounds is increasing.

As a typical charge generating substance having sensitivity in the infrared region, phthalocyanine and the like can be mentioned, and among them, highly sensitive oxytitanium phthalocyanine has been studied in many cases.

[0008] For example, oxytitanium phthalocyanine, like other phthalocyanines, is known in many crystal forms, and studies on it are being conducted.

As a specific example, see Japanese Patent Application Laid-Open No. 61-23924.
No. 8, JP-A-62-67094,
The crystal forms disclosed in JP-A No. 17066, JP-A-3-524264, and JP-A-3-128973 are exemplified.

[0010] However, oxytitanium phthalocyanine has high sensitivity, but has a problem that the potential characteristics are easily changed by repeated use.

On the other hand, as an exposure means used in a laser beam printer or a digital copying machine, a laser beam corresponding to an image signal from a semiconductor laser is reflected by a rotating polygon mirror (hereinafter, referred to as a polygon mirror), and the reflected light is electrophotographed. A method of forming an electrostatic latent image by irradiating the surface of the photoreceptor is exemplified.

In the case of such an exposure means using a laser beam, it is necessary to increase the scanning speed of the laser beam in order to realize a high-definition and high-speed output image with one laser beam. However, there is a limit to the rotation speed of the polygon mirror.

Therefore, as a means for solving this problem,
A multi-beam system in which an electrophotographic photosensitive member is scanned at once by a plurality of laser beams has been proposed and realized.

This multi-beam system has the following advantages.

In the case of an image forming apparatus using n laser beams, when the scanning speed and the printing speed of the laser beam are set equal to those when a single laser beam is used, the density of the scanning lines is n. Can be doubled,
High-resolution image recording becomes possible.

Further, when the scanning speed of the laser beam and the density of the scanning lines are set to be equal to those in a single case, it is possible to increase the printing speed by n times. Further, when the print speed and the scanning density of the laser beam are set to be equal to that of a single case, the scanning speed of the laser beam, that is, the number of rotations of the polygon mirror can be made 1 / n times, and the polygon mirror is rotationally driven. Therefore, there is an effect that the mechanism for performing the operation can be simplified and the cost can be reduced.

However, in the case of an electrophotographic apparatus using the above-described multi-beam type exposure means, despite the formation of the same electrostatic latent image, the time when a plurality of adjacent laser beams are emitted at the same time and When the laser beams are sequentially and individually emitted, a difference may occur in the density of an output image.

Also, in an electrophotographic apparatus having no static elimination means such as pre-exposure, a ghost in which the history of the exposed portion remains on the image in the next cycle as compared with the case where one laser beam is used. A phenomenon called "a" sometimes appeared.

These phenomena occur more remarkably when oxytitanium phthalocyanine is used as the charge generating substance of the electrophotographic photosensitive member.

[0020]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a multi-beam type exposure means, and even when no static elimination means such as pre-exposure is used, a density difference is obtained irrespective of the laser beam emission state. An object of the present invention is to provide an electrophotographic apparatus and a process cartridge which are unlikely to cause a change in potential due to ghost and repeated use.

[0021]

That is, the present invention provides an electrophotographic photosensitive member having a photosensitive layer on a support, a charging means for charging the electrophotographic photosensitive member, and an electrophotographic photosensitive member using a plurality of laser beams. Multi-beam type exposure means for forming an electrostatic latent image on a photographic photosensitive member, developing means for developing with a toner on an electrophotographic photosensitive member having an electrostatic latent image formed thereon, and transfer of a toner image on the electrophotographic photosensitive member A transfer unit for transferring the image onto the body; and an electrophotographic apparatus having no charge removing means for uniformly removing an electrostatic latent image on the electrophotographic photosensitive member prior to the charging means. The photosensitive layer contains oxytitanium phthalocyanine, and the electrophotographic photosensitive member has a charge mobility of 7.0 × 10 ^{−7 to} 2.0 × 10 ⁻⁵ cm ² / V ·.
s is an electrophotographic apparatus.

Further, the present invention provides an electrophotographic photosensitive member having a photosensitive layer on a support and an electrostatic latent image formed on the surface by a plurality of laser beams, and a charging means for charging the electrophotographic photosensitive member And at least one of developing means for developing the electrophotographic photosensitive member on which the electrostatic latent image has been formed with toner, and integrally supporting the electrostatic latent image on the electrophotographic photosensitive member using the plurality of laser beams. Process which comprises a multi-beam type exposure means for forming an image, and which is detachable from an electrophotographic apparatus main body which does not have a charge removing means for uniformly removing an electrostatic latent image on the electrophotographic photosensitive member prior to the charging means. In the cartridge, the photosensitive layer of the electrophotographic photosensitive member contains oxytitanium phthalocyanine, and the charge mobility of the electrophotographic photosensitive member is from 7.0 × 10 ^{−7 to} 2.0 × 10 ⁻⁵ cm ^2.
/ V · s.

The present invention also relates to an electrophotographic photoreceptor having a photosensitive layer on a support, wherein the electrophotographic photoreceptor, charging means for charging the electrophotographic photoreceptor, and a plurality of laser beams are used. Multi-beam exposure means for forming an electrostatic latent image on the electrophotographic photoreceptor, developing means for developing the electrophotographic photoreceptor on which the electrostatic latent image is formed with toner, and toner on the electrophotographic photoreceptor Transfer means for transferring an image onto a transfer body, and an electrophotographic photosensitive member for an electrophotographic apparatus, which does not include a charge removing means for uniformly removing an electrostatic latent image on the electrophotographic photosensitive member prior to the charging means. Wherein the photosensitive layer contains oxytitanium phthalocyanine and has a charge mobility of 7.0.
An electrophotographic photoreceptor which is a ^{× 10 -7 ~2.0 × 10 -5 cm} 2 / V · s.

[0024]

Embodiments of the present invention will be described below in detail.

Since the electrophotographic photosensitive member used in the electrophotographic apparatus and the process cartridge of the present invention has a specific charge mobility, a density difference hardly occurs irrespective of the light emission state of the laser beam. It has electrophotographic characteristics in which potential fluctuation due to ghosting and repeated use is unlikely to occur without the charge removing means.

In an electrophotographic apparatus using a multi-beam type exposure means, there is a difference in the density of an output image between when a plurality of adjacent laser beams are simultaneously emitted and when each of the laser beams is sequentially and individually emitted. Is related to the overlap of the laser beam spots, which is considered to be caused by the difference in the potential characteristics of the electrophotographic photosensitive member at the overlap portion.

When a plurality of laser beams are emitted at the same time, an overlapping portion of the laser spot is irradiated on the electrophotographic photosensitive member in a state where a plurality of lights are combined. On the other hand, when laser beams are sequentially emitted individually, light is irradiated twice without being combined.

Thus, the phenomenon that the potential characteristics of the electrophotographic photosensitive member produce a difference even though the same amount of light is irradiated is called reciprocity failure.

In general, the light intensity E at the light emission intensity I and the exposure time t is E = I × t, and the potential V of the electrophotographic photosensitive member is
Is determined as a function of the amount of light E on the electrophotographic photosensitive member. However, when the light emission intensity I is too high or too low, the potential V of the electrophotographic photosensitive member is different despite the same light amount E on the electrophotographic photosensitive member,
A phenomenon called reciprocity failure occurs where the reciprocity is not followed. In connection with this reciprocity failure, there is also a phenomenon that it is better to irradiate the electrophotographic photosensitive member repeatedly with relatively low light intensity than to irradiate the electrophotographic photosensitive member all at once.
No. 3 publication.

That is, in an electrophotographic apparatus using the exposure means of the multi-beam system, the difference in the density of the output image is lower when the laser beams are simultaneously emitted than when the laser beams are individually emitted sequentially. Likely to occur.

The inventors of the present invention have focused on the charge mobility of the electrophotographic photosensitive member, and as a result, have found that the charge mobility is 2.
When it is 0 × 10 ⁻⁵ cm ² / V · s or less, when laser beams are sequentially emitted individually, the potential decay of the overlapping portion of the laser from the first laser irradiation until the next laser irradiation is performed. It has been found that it is difficult to cause a potential difference as a result of the simultaneous light emission.

Further, the charge mobility is 7.0 × 10 ⁻⁷ or ^less .
Within the range of 2.0 × 10 ⁻⁵ cm ² / V · s, it has been found that potential fluctuation due to ghosting and repeated use is unlikely to occur, and the present invention has been achieved.

It is not clear why such a remarkable effect can be obtained with respect to potential fluctuation due to ghost and repeated use. However, in the case where a plurality of laser beams are used, compared with the case of using a single laser beam, the charge is easily accumulated inside the electrophotographic photosensitive member because the sensitivity is deteriorated in the portion where the light is emitted simultaneously. It is presumed that this affects ghosts and potential fluctuations due to repeated use.

Specifically, it is presumed that, with respect to the ghost, although an appropriate charge accumulation occurs by specifying a specific charge mobility, an increase in the charge accumulation due to repeated use can be suppressed, so that it is hardly caused. You. In addition, regarding the potential fluctuation due to repeated use, the charge accumulation due to repeated use is appropriately maintained by specifying a specific charge mobility, which is well offset by a potential fluctuation factor considered to be caused by oxytitanium phthalocyanine. It is presumed that this is unlikely to occur.

The oxytitanium phthalocyanine used in the present invention is represented by the following structural formula (1).

[0036]

[Outside 1]

Wherein X ¹ , X ² , X ³ and X ⁴ are Cl
Or Br, and h, i, j, and k are integers from 0 to 4.

In the present invention, the crystal form of oxytitanium phthalocyanine is not particularly limited.
The black angle (2θ ± 0.
2 °) 9.0 °, 14.2 °, 23.9 ° and 2
From the viewpoint of sensitivity characteristics, it is more preferable that the oxytitanium phthalocyanine having a strong peak at 7.1 ° or the oxytitanium phthalocyanine having strong peaks at 9.6 ° and 27.3 ° is used.

The electrophotographic photosensitive member used in the present invention comprises
It has a charge mobility of 7.0 × 10 ^{−7 to} 2.0 × 10 ⁻⁵ cm ² / V · s, but in particular, 1.0 × 10 ⁻⁶ to
Preferably it has a charge mobility of ^{1.0 × 10 -5 cm 2 / V} · s, 1.5 × 10 - 6 ~6.5 × 10 -6
More preferably, it has a charge mobility of cm ² / V · s.

The charge mobility is 7.0 × 10 ⁻⁷ cm ² / V
If the value is smaller than s, the effect on potential fluctuation due to ghost or repeated use becomes insufficient. On the other hand, if the charge mobility is larger than 2.0 × 10 ⁻⁵ cm ² / V · s, the effect on the density difference of the output image due to the light emitting state of the laser beam and the potential fluctuation due to repeated use becomes insufficient.

The charge mobility defined in the present invention means a characteristic value defined as a charge transfer speed per unit electric field intensity.

As a method of measuring the charge mobility,
Usually, a method called a time-of-flight (TOF) method is used. This measurement method uses a sample called a sandwich cell in which both surfaces of a photosensitive layer are sandwiched between electrodes, forms an electric field by applying a voltage between the electrodes, and then irradiates the sample with pulsed light through the electrodes. Then, the waveform of the transient current flowing between the electrodes in the process in which the generated charges move from one surface of the sample to the opposing surface is observed. Charge mobility can be derived by analyzing this transient current waveform.

The electrophotographic apparatus of the present invention can be used even when the electric field strength of the electrophotographic photoreceptor is small or the influence of the overlapping portion of the laser beam spot becomes large as in the case where the resolution of the electrophotographic apparatus is high. It has electrophotographic characteristics in which a difference in density hardly occurs irrespective of the light emission state of the beam, and furthermore, a potential change due to ghost and repeated use hardly occurs even without a charge removing means such as pre-exposure.

Specifically, the electric field strength of the electrophotographic photosensitive member is not more than 3.5 × 10 ⁵ V / cm, particularly 3 × 10 ⁵ V / c.
m or less, and even when the resolution of the electrophotographic apparatus is 1200 dpi or more, a density difference hardly occurs irrespective of the emission state of the laser beam, and there is no charge removing means such as pre-exposure. However, it has electrophotographic characteristics in which potential fluctuation due to ghosting and repeated use hardly occurs.

Further, the electrophotographic apparatus of the present invention has an electrophotographic characteristic in which a density difference hardly occurs irrespective of the emission state of the laser beam even when the process speed is slow, that is, when the scanning time of the laser beam is long. Is what you have.

Specifically, even when the process speed of the electrophotographic apparatus is 200 mm / s or less, particularly 160 mm / s or less, the electrophotographic apparatus has electrophotographic characteristics in which a difference in density hardly occurs irrespective of the emission state of the laser beam. ing.

Hereinafter, the configuration of the electrophotographic photosensitive member used in the electrophotographic apparatus and the process cartridge of the present invention will be described.

The electrophotographic photoreceptor used in the electrophotographic apparatus and the process cartridge of the present invention has a charge transporting substance even if the photosensitive layer is a single layer containing a charge transporting substance and a charge generating substance in the same layer. May be separated into a charge-transporting layer containing a compound and a charge-generating layer containing a charge-generating substance. Further, it is preferable that a charge transport layer is provided on the charge generation layer, and the charge transport layer is a surface layer. Hereinafter, this embodiment will be described as an example.

The support to be used may be any one having conductivity, such as a metal such as aluminum or stainless steel, or a metal provided with a conductive layer, paper, plastic, or the like. Is mentioned.

When the exposure light is coherent light, a conductive layer may be provided on the support for the purpose of preventing interference fringes due to scattering or covering a damage on the support. The conductive layer can be formed by dispersing a conductive powder such as carbon black or metal particles in a resin. The thickness of the conductive layer is preferably from 5 to 40 μm, more preferably from 10 to 30 μm.

An intermediate layer having an adhesive function and a barrier function may be provided between the support and the photosensitive layer. Examples of the material of the intermediate layer include polyamide, polyvinyl alcohol, polyethylene oxide, ethyl cellulose, casein, polyurethane, and polyether urethane. These are dissolved in an appropriate solvent and applied. The thickness of the intermediate layer is preferably from 0.05 to 5 μm, more preferably from 0.3 to 1 μm.

The charge generation layer contains a charge generation material of 0.3 to 4
Homogenizer, ultrasonic dispersion, ball mill, vibrating ball mill, sand mill, with double amount of appropriate resin and solvent,
It is formed by applying and drying a dispersion liquid uniformly dispersed by a dispersion method such as an attritor, a roll mill and a liquid collision type high-speed disperser.

As the charge generating material, the above-mentioned oxytitanium phthalocyanine is used.

Examples of the binder resin used include polyvinyl butyral resin, polyester resin, acrylic resin, phenoxy resin, polycarbonate resin,
Examples include a polyvinyl acetal resin, a polystyrene resin, and a polyarylate resin. The thickness of the charge generation layer is preferably 5 μm or less, more preferably 0.1 to 2 μm.
m.

The charge transporting layer is formed by applying a coating solution in which a charge transporting substance and a binder resin are dissolved in a solvent, followed by drying.

Examples of the charge transport material include triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, triallylmethane compounds and thiazole compounds.

Examples of the binder resin used include acrylic resin, polyester resin, polyarylate resin, polyvinyl chloride resin, polycarbonate resin, polyvinyl butyral resin, and polymethacrylate resin.

[0058] These charge transporting substance and a binder resin, charge mobility 7.0 × ^{10 -} 7 ~2.0 × ^10
It is appropriately combined so as to be ⁻⁵ cm ² / V · s.

The content of the charge transport material in the charge transport layer is as follows:
It is preferably less than 50% by mass, more preferably 42 to 46% by mass, based on the total mass of the charge transport layer.

The thickness of the charge transport layer is preferably 5 to 40 μm, more preferably 15 to 30 μm, and further preferably 25 to 2 μm.
8 μm is particularly preferred. However, since the thickness of the charge transport layer also affects the charge mobility, the charge transport layer has a thickness of 7.0 × 10 ^{−7 to} 2.0 ×.
It is necessary to set so as to be in the range of 10 ⁻⁵ cm ² / V · s.

Next, the exposure apparatus used in the present invention will be described.

FIG. 2 shows a schematic configuration of a multi-beam type exposure apparatus having two laser beams.

As shown in FIG. 2, the exposure apparatus includes a semiconductor laser 20, which is a light emitting source of a laser beam, a collimator lens 21 and a diaphragm 22, which collimate the emitted laser beam and adjust the beam diameter to a predetermined beam diameter. The polygon mirror 23 changes the angle by continuously reflecting the light beam incident thereon by rotation at a constant angular velocity in the direction, and the f-θ lens 24 focuses the reflected light beam on the electrophotographic photosensitive member 1.

The semiconductor laser 20, which is a light emitting source, has a structure as shown in FIG. 3, and emits two laser beams. An electrode substrate 31 on the lower surface and an LD chip (laser diode chip) 32 mounted thereon.
The LD chip 32 includes two oscillation regions 34 and 35 separated by a separation groove above a chip substrate 33.
Are provided. When a drive current is supplied from the connection terminals Ta and Tb connected to an LD drive circuit (not shown) via the electrodes 34a and 35a, the laser diodes LD1 and LD2 cause the first and second laser beams L
1, L2 forward and back beams L1 ', L2'
Is emitted backward.

The semiconductor laser 20 includes a photodiode 36, and the photodiode 3
Numeral 6 stabilizes the laser beam by receiving the back beams L1 'and L2' and feeding back the light amount signal to a laser beam emission bias power source to automatically control the amount of bias current.

FIG. 1 shows a schematic configuration of an electrophotographic apparatus provided with a process cartridge having the electrophotographic photosensitive member of the present invention.

In FIG. 1, reference numeral 1 denotes a drum-shaped electrophotographic photosensitive member which is driven to rotate at a predetermined peripheral speed in the direction of the arrow. In the rotation process, the peripheral surface of the electrophotographic photosensitive member 1 is uniformly charged with a predetermined positive or negative potential by the primary charging unit 2, and then a multi-beam exposure unit (not shown) having a plurality of laser beams. Receives the exposure light 3 which is emphasized and modulated in correspondence with the time-series electric digital image signal of the target image information output from. In this way, an electrostatic latent image corresponding to the target image information is sequentially formed on the peripheral surface of the electrophotographic photosensitive member 1.

The formed electrostatic latent image is then transferred to developing means 4
The transfer material 6 is removed from a paper feeding unit (not shown) between the electrophotographic photosensitive member 1 and the transfer unit 5 in synchronization with the rotation of the electrophotographic photosensitive member 1 and fed. The toner images formed and carried on the surface of the photoconductor 1 are sequentially transferred by the transfer unit 5.

The transfer material 6 to which the toner image has been transferred is separated from the surface of the electrophotographic photosensitive member, introduced into the image fixing means 7 and subjected to image fixing to be printed out of the apparatus as an image formed product (print, copy). Be out.

The surface of the electrophotographic photosensitive member 1 after the transfer of the image is cleaned by the cleaning means 8 to remove the untransferred toner, and is used repeatedly for image formation.

In the present invention, among the above-mentioned components such as the electrophotographic photosensitive member 1, the primary charging means 2, the developing means 4 and the cleaning means 8, a plurality of components are housed in a container and integrally combined as a process cartridge 9. And configure
The process cartridge 9 is configured to be detachable from a main body of an electrophotographic apparatus such as a copying machine or a laser beam printer. For example, at least one of the primary charging unit 2, the developing unit 4, and the cleaning unit 8 is integrally supported with the electrophotographic photosensitive member 1 to form a cartridge, and is attached to and detached from the apparatus main body using a guide unit 10 such as a rail of the apparatus main body. A flexible process cartridge can be provided.

[0072]

Hereinafter, the present invention will be described in more detail with reference to specific examples. In addition, "part" in an Example shows a mass part.

(Example 1) Diameter 30 mm, length 260 m
m aluminum cylinder as a support, and a coating liquid composed of the following materials is applied to the support by a dipping method, heat-cured at 140 ° C. for 30 minutes, and dried. A layer was formed.

Conductive pigment: SnO ₂ coated barium sulfate 10 parts Resistance adjusting pigment: titanium oxide 2 parts Binder resin: phenol resin 6 parts Leveling material: silicone oil 0.001 parts Solvent: methanol, methoxypropanol 0.2 / 0.
8 20 parts Next, a solution prepared by dissolving 3 parts of N-methoxymethylated nylon and 3 parts of copolymerized nylon in a mixed solvent of 65 parts of methanol / 30 parts of n-butanol was applied thereon by dipping, and dried, An intermediate layer having a thickness of 0.5 μm was formed.

Next, in the characteristic X-ray diffraction of CuKα, the Bragg angles (2θ ± 0.2 °) of 9.0 °, 14.2 °,
Sand mill apparatus using 4 parts of oxytitanium phthalocyanine having strong peaks at 23.9 ° and 27.1 °, 4 parts of polyvinyl butyral (trade name: Esrec BM2, manufactured by Sekisui Chemical) and 60 parts of cyclohexanone using glass beads having a diameter of 1 mm. For 4 hours, and 100 parts of ethyl acetate was added to prepare a dispersion for a charge generation layer. This is applied by a dipping method and dried, and the film thickness is 0.2 μm.
m of the charge generation layer was formed.

Next, 8 parts of a compound represented by the following structural formula (2):

[Outside 2]

2 parts of a compound of the following structural formula (3):

[Outside 3]

12 parts of polycarbonate Z resin (weight average molecular weight: 100,000) were dissolved in a mixed solvent of 60 parts of monochlorobenzene / 40 parts of dichloromethane.

This paint was applied by a dipping method and dried at 110 ° C. for 2 hours to form a charge transport layer having a thickness of 25 μm.

Further, each layer similar to the electrophotographic photosensitive member was formed on an aluminum sheet, and the charge mobility was measured using a sample on which gold was vacuum-deposited so as to be translucent.

In the case of the layer configuration of this embodiment, the presence of layers other than the photosensitive layer can be ignored for deriving the electric field intensity applied to the electrophotographic photosensitive member. The value Vd / D (V / cm) divided by the film thickness D (cm) of the photosensitive layer (charge generation layer and charge transport layer) can be used as the electric field intensity, and this value was used in this example. However, if it cannot be ignored, it is necessary to derive the electric field strength in consideration of them.

The charge mobility was measured by the TOF method.
As a method, a voltage is applied to the measurement sample so as to be the same potential as the dark portion potential, and then a pulse light is irradiated by a laser diode having a wavelength of 680 nm to generate charges from the charge generation layer. The measurement was performed using a high-speed current amplifier (Keithley 428) and a digital oscilloscope (Tektronix TDS420A). In order to determine the transit time, a relationship between the current (i) and the time (t) is logarithmically converted and the relation is obtained from a bending point of the obtained waveform (Scherer).
-Montroll method).

Next, the image evaluation will be described. The apparatus was modified from an Hewlett-Packard LBP “Laser Jet 4000” (process speed 94 mm / s, resolution 600 dpi, electrophotographic apparatus without static elimination means). In the modification, the exposure means of the apparatus was changed to a multi-beam exposure means having two laser beams, and the process speed was increased to 190 mm / s (resolution 600d).
pi). Also, the potential setting of this device is
The voltage was adjusted to 700 V and the bright portion potential to -150 V. This apparatus does not include a static elimination means.

Using the produced electrophotographic photoreceptor, a halftone image consisting of two dot lines simultaneously emitting laser beams in an environment of 23 ° C./50% RH using this apparatus and two dots sequentially emitting each laser beam A halftone image consisting of lines was output, and the difference in image density between the two was evaluated. The evaluation was carried out by visual inspection, and those with no apparent density difference were A, those with a slight density difference were B, those with a density difference were C, and those with a large density difference were D.
Further, for the C rank, ranking was performed according to the level difference. C1 having a good level was designated as C1, and C2 having a bad level was designated.

Next, 1000 sheets of continuous printing were performed in this apparatus under the environment of 23 ° C./50% RH, and an image pattern was output in which the solid black of 25 mm square was a halftone after the end of the endurance and after the end of 1000 sheets. The ghost was evaluated. The durable image was a horizontal line pattern with a printing rate of 5%.
The evaluation was performed by visual inspection. A for which no ghost was confirmed on the halftone was evaluated as A, and B was evaluated when the density on the halftone after solid black was slightly higher than that of the other halftone image areas. A sample having a density higher than that of the other halftone image portion was designated C, and a sample having a density clearly higher than the other halftone image portions was designated D. Contrary to this, B ', C', and D 'are those in which the density on the halftone after the solid black is lighter than the other halftone image portions. Further, for the C or C 'rank, the ranking is performed according to the level difference,
A good level was C1 or C1 ', and a bad level was C2 or C2'.

Further, the durability of the intermittent paper passing one stop for each print was repeated 5000 times in an environment of 23 ° C./50% RH in this apparatus, and the potential characteristics were evaluated. The durable image was a random combination of solid white, solid black, halftone, a character pattern with a printing rate of 4%, and a horizontal line pattern with a printing rate of 5%. The evaluation was for the endurance early stage and 2
The light area potential was measured every time the sheet was lasted for 5,000 sheets.
The difference between the two points having the largest potential difference was determined throughout the durability of the sheet.

After that, the durability of 5,000 sheets is further performed.
Evaluation of the potential characteristics after 10,000 sheets of durability was performed. In the evaluation, the bright portion potential was measured at the initial stage of the durability test and at the end of every 200 prints, and the difference between the two points having the largest potential difference from the initial run through 10,000 prints was determined.

Table 1 shows the results.

Example 2 The thickness of the charge transport layer was 19 μm
An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except that the above conditions were satisfied.

Table 1 shows the results.

Example 3 Electrons were prepared in the same manner as in Example 1 except that 15 parts of the compound of the structural formula (2) and 3 parts of the compound of the structural formula (3) were used as the charge transporting material of the charge transporting layer. A photoreceptor was prepared and evaluated.

Table 1 shows the results.

Example 4 Electrons were prepared in the same manner as in Example 1 except that 5 parts of the compound of the structural formula (2) and 1 part of the compound of the structural formula (3) were used as the charge transporting material of the charge transporting layer. A photoreceptor was prepared and evaluated.

Table 1 shows the results.

(Example 5) As a charge transporting substance of a charge transporting layer, 8 parts of a compound represented by the following structural formula (4):

[Outside 4]

2 parts of a compound of the following structural formula (5):

[Outside 5]

An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that the above was used. Table 1 shows the results.

Example 6 14 parts of a compound represented by the following structural formula (6) was used as a charge transport material:

[Outside 6]

An electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1 except for using.

Table 1 shows the results.

(Embodiment 7) Up to the charge generation layer, Embodiment 1
In the same manner as described above, as the charge transport layer forming step, 10 parts of the compound of the structural formula (2) and 10 parts of a resin having a structural unit of the following formula (7) (weight average molecular weight: 100,000)

[Outside 7]

Was dissolved in a mixed solvent of 80 parts of monochlorobenzene / 40 parts of dichloromethane.

This paint was applied by a dipping method,
After drying for a time, a charge transport layer having a thickness of 25 μm was formed.
This electrophotographic photosensitive member was evaluated in the same manner as in Example 1.

Table 1 shows the results.

(Embodiment 8) Up to the charge generation layer, Embodiment 1
As a charge transport layer forming step, 10 parts of tetrafluoroethylene resin particles (trade name: Lubron L-2, manufactured by Daikin), 10 parts of polycarbonate Z resin (weight average molecular weight: 50,000), and a fluorine-based resin After sufficiently mixing 0.06 parts of a type graft polymer (trade name: GF300, manufactured by Toa Kasei) with 60 parts of monochlorobenzene, the mixture was dispersed with a high-pressure dispersing machine to prepare a dispersion of tetrafluoroethylene resin particles.

Next, 8 parts of the compound of structural formula (2), 3 parts of the compound of structural formula (3), 6 parts of polycarbonate Z resin (weight average molecular weight: 50,000), and 6 parts of polycarbonate Z resin (weight average molecular weight: 20,000) ) And 16 parts of a tetrafluoroethylene resin particle dispersion (2 parts of a polycarbonate Z resin (weight average molecular weight: 50,000)) were dissolved in a mixed solvent of 40 parts of monochlorobenzene / 30 parts of dichloromethane.

This paint was applied by a dipping method,
After drying for a time, a charge transport layer having a thickness of 25 μm was formed.
This electrophotographic photosensitive member was evaluated in the same manner as in Example 1.

Table 1 shows the results.

Example 9 Evaluation was performed in the same manner as in Example 1 except that the process speed of the electrophotographic apparatus was set to 150 mm / s. Table 1 shows the results.

Example 10 Evaluation was performed in the same manner as in Example 1 except that the process speed of the electrophotographic apparatus was set to 210 mm / s.

Table 1 shows the results.

Example 11 Evaluation was performed in the same manner as in Example 1 except that the image resolution of the electrophotographic apparatus was set to 1200 dpi.

Table 1 shows the results.

Example 12 Evaluation was made in the same manner as in Example 3 except that the process speed of the electrophotographic apparatus was set to 150 mm / s.

Table 1 shows the results.

Example 13 Evaluation was performed in the same manner as in Example 2 except that the process speed of the electrophotographic apparatus was set to 150 mm / s.

Table 1 shows the results.

Example 14 Evaluation was performed in the same manner as in Example 4 except that the process speed of the electrophotographic apparatus was set to 210 mm / s.

Table 1 shows the results.

Example 15 Evaluation was performed in the same manner as in Example 5, except that the process speed of the electrophotographic apparatus was set to 210 mm / s.

Table 1 shows the results.

Example 16 Evaluation was performed in the same manner as in Example 3 except that the image resolution of the electrophotographic apparatus was set to 1200 dpi.

Table 1 shows the results.

Example 17 Evaluation was performed in the same manner as in Example 2 except that the image resolution of the electrophotographic apparatus was 1200 dpi.

Table 1 shows the results.

Example 18 Evaluation was performed in the same manner as in Example 5 except that the image resolution of the electrophotographic apparatus was set to 1200 dpi.

Table 1 shows the results.

Example 19 Evaluation was made in the same manner as in Example 4 except that the image resolution of the electrophotographic apparatus was 1200 dpi.

Table 1 shows the results.

Example 20 The compound of the structural formula (2) was converted to
And an electrophotographic photoreceptor was prepared and evaluated in the same manner as in Example 1, except that the thickness of the charge transport layer was 28 μm.

Table 1 shows the results.

Example 21 Evaluation was made in the same manner as in Example 20, except that the process speed of the electrophotographic apparatus was set to 150 mm / s.

Table 1 shows the results.

Example 20 Evaluation was made in the same manner as in Example 20, except that the image resolution of the electrophotographic apparatus was 1200 dpi.

Table 1 shows the results.

Comparative Example 1 An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that 24 parts of the compound of the structural formula (2) was used as the charge transporting material of the charge transporting layer.

The results are shown in Table 1.

(Comparative Example 2) An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Example 1 except that 5 parts of the compound of the structural formula (3) was used as the charge transporting material of the charge transporting layer.

The results are shown in Table 1.

Comparative Example 3 Evaluation was made in the same manner as in Comparative Example 1 except that the process speed of the electrophotographic apparatus was changed to 150 mm / s.

Table 1 shows the results.

Comparative Example 4 Evaluation was made in the same manner as in Comparative Example 2 except that the process speed of the electrophotographic apparatus was 210 mm / s.

Table 1 shows the results.

Comparative Example 5 Evaluation was made in the same manner as in Comparative Example 1 except that the image resolution of the electrophotographic apparatus was 1200 dpi.

The results are shown in Table 1.

Comparative Example 6 Evaluation was performed in the same manner as in Comparative Example 2 except that the image resolution of the electrophotographic apparatus was 1200 dpi.

The results are shown in Table 1.

Reference Example 1 An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Comparative Example 1, except that an exposure means having one laser beam was used. However, the rotation speed of the polygon mirror had to be doubled as compared with another example employing a multi-beam type exposure means having two laser beams.

The results are shown in Table 1.

Reference Example 2 An electrophotographic photosensitive member was prepared and evaluated in the same manner as in Comparative Example 2 except that an exposure means having one laser beam was used. However, the rotation speed of the polygon mirror had to be doubled as compared with another example employing a multi-beam type exposure means having two laser beams.

Table 1 shows the results.

(Reference Example 3) Up to the intermediate layer, the same procedure as in Example 1 was carried out, and as a charge generation layer preparation step, 4 parts of a charge generation material represented by the following structure and 70 parts of tetrahydrofuran were mixed with glass beads having a diameter of 1 mm. 1 with the used sand mill
After dispersing for 0 hour, a solution prepared by dissolving 2 parts of polyvinyl butyral resin (ESLEK BLS, manufactured by Sekisui Chemical) in 20 parts of tetrahydrofuran was added, and the mixture was further dispersed for 2 hours. Further, the glass beads are separated and cyclohexanone 1
By adding 00 parts, a dispersion for the charge generation layer was prepared. This dispersion is applied on the intermediate layer by a dipping method, dried, and dried to a film thickness of 0.
A 2 μm charge generation layer was formed.

[0153]

[Outside 8]

Next, a charge transport layer was formed in the same manner as in Comparative Example 1. This electrophotographic photosensitive member was evaluated in the same manner as in Example 1. Table 1 shows the results.

(Reference Example 4) Up to the charge generation layer, Reference Example 3
The charge transport layer was prepared in the same manner as in Comparative Example 2 and evaluated.

Table 1 shows the results.

[0157]

[Table 1]

[0158]

As described above, according to the present invention, even when the multi-beam type exposure means is used and the static elimination means such as pre-exposure is not used, the density difference does not depend on the laser beam emission state. This makes it possible to provide an electrophotographic apparatus and a process cartridge in which the occurrence of ghosts and the potential fluctuation due to ghosting and repeated use are unlikely to occur.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a schematic configuration of an electrophotographic apparatus including a process cartridge having an electrophotographic photosensitive member according to the present invention.

FIG. 2 is a diagram showing a schematic configuration of a multi-beam type exposure apparatus having two laser beams.

FIG. 3 is a diagram showing a schematic configuration of a semiconductor laser.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Charging means 3 Exposure light 4 Developing means 5 Transfer means 6 Transfer material 7 Fixing means 8 Cleaning means 9 Process cartridge 10 Guide means 20 Semiconductor laser 21 Collimator lens 22 Aperture 23 Polygon mirror 24 f-θ lens 31 Electrode Substrate 32 LD chip 33 Chip substrate 34, 35 Oscillation area 34a, 35a Electrode L1, L2 Laser beam L1 ', L2' Back beam

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H068 AA19 AA28 AA29 AA37 BA39 FA13 FA27 FC01 FC05 FC11 FC15

Claims (30)

[Claims] 1. An electrophotographic photosensitive member having a photosensitive layer on a support, a charging means for charging the electrophotographic photosensitive member, and forming an electrostatic latent image on the electrophotographic photosensitive member using a plurality of laser beams. Multi-beam type exposure means, developing means for developing toner on the electrophotographic photosensitive member having the electrostatic latent image formed thereon, and transfer means for transferring the toner image on the electrophotographic photosensitive member onto the transfer body An electrophotographic apparatus having no static elimination means for uniformly eliminating an electrostatic latent image on the electrophotographic photosensitive member prior to the charging means, wherein the photosensitive layer of the electrophotographic photosensitive member contains oxytitanium phthalocyanine; 6. The charge mobility of the electrophotographic photosensitive member is 7.
An electrophotographic apparatus characterized by having a density of 0 × 10 ^{−7 to} 2.0 × 10 ⁻⁵ cm ² / V · s. 2. The electrophotographic apparatus according to claim 1, wherein the electric field strength is 3.5 × 10 ⁵ V / cm or less. 3. The electrophotographic apparatus according to claim 1, wherein the image resolution is 1200 dpi or more. 4. The electrophotographic apparatus according to claim 1, wherein a process speed is 200 mm / s or less. 5. A first transfer means for transferring the toner image on the electrophotographic photosensitive member to an intermediate transfer member, and a second transfer means for transferring the toner image on the intermediate transfer member to the transfer material. The electrophotographic apparatus according to claim 1, further comprising a transfer unit. 6. The electrophotographic apparatus according to claim 1, wherein the photosensitive layer of the electrophotographic photosensitive member has a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance. 7. The electrophotographic apparatus according to claim 6, wherein the charge transport layer is a surface layer of the electrophotographic photosensitive member. 8. The charge transport layer has a thickness of 25 to 28 μm.
The electrophotographic apparatus according to claim 6, wherein: 9. The charge transport material according to claim 6, wherein the content of the charge transport material is 42 to 46% by mass based on the total mass of the charge transport layer.
An electrophotographic apparatus according to any one of claims 1 to 8. 10. The electron according to claim 1, wherein the charge mobility of the electrophotographic photoreceptor is 1.5 × 10 ^{−6 to} 6.5 × 10 ⁻⁶ cm ² / V · s. Photo equipment. 11. An electrophotographic photosensitive member having a photosensitive layer on a support, on which an electrostatic latent image is formed by a plurality of laser beams, a charging means for charging the electrophotographic photosensitive member, and an electrostatic latent image At least one of developing means for developing the electrophotographic photosensitive member on which an image is formed with toner is integrally supported, and a plurality of laser beams are used to form an electrostatic latent image on the electrophotographic photosensitive member. A process cartridge that includes a beam type exposure unit and is detachable from an electrophotographic apparatus main body that does not include a charge removing unit that uniformly removes an electrostatic latent image on the electrophotographic photosensitive member prior to the charging unit;
The photosensitive layer of the electrophotographic photosensitive member contains oxytitanium phthalocyanine, and the charge mobility of the electrophotographic photosensitive member is 7.
A process cartridge characterized by having a pressure of 0 × 10 ^{−7 to} 2.0 × 10 ⁻⁵ cm ² / V · s. 12. An electrophotographic apparatus having an electric field strength of 3.5.
The process cartridge according to claim 11, wherein the pressure is equal to or less than × 10 ⁵ V / cm. 13. An electrophotographic apparatus having an image resolution of 12
The process cartridge according to claim 11, wherein the process cartridge is at least 00 dpi. 14. The process cartridge according to claim 1, wherein the process speed of the electrophotographic apparatus is 200 mm / s or less. 15. The electrophotographic apparatus has a transfer unit,
The transfer unit has a first transfer unit that transfers a toner image on the electrophotographic photosensitive member to an intermediate transfer member, and a second transfer unit that transfers the toner image on the intermediate transfer member to the transfer material. The process cartridge according to claim 11. 16. The process cartridge according to claim 11, wherein the photosensitive layer of the electrophotographic photosensitive member has a charge generation layer and a charge transport layer. 17. The process cartridge according to claim 16, wherein the charge transport layer is a surface layer of the electrophotographic photosensitive member. 18. The charge transport layer having a thickness of 25 to 28 μm.
The process cartridge according to claim 16, wherein m is m. 19. The process cartridge according to claim 16, wherein the content of the charge transport material is 42 to 46% by mass based on the total mass of the charge transport layer. 20. The process according to claim 11, wherein the charge mobility of the electrophotographic photoreceptor is 1.5 × 10 ^{−6 to} 6.5 × 10 ⁻⁶ cm ² / V · s. cartridge. 21. An electrophotographic photosensitive member having a photosensitive layer on a support, comprising: an electrophotographic photosensitive member; charging means for charging the electrophotographic photosensitive member; and a plurality of laser beams. A multi-beam type exposing means for forming an electrostatic latent image on the photoreceptor, a developing means for developing the electrophotographic photoreceptor having the electrostatic latent image formed thereon with toner, and a transfer member for transferring the toner image on the electrophotographic photoreceptor An electrophotographic photosensitive member for an electrophotographic apparatus, which does not include a discharging unit for uniformly discharging an electrostatic latent image on the electrophotographic photosensitive member prior to the charging unit. The photosensitive layer contains oxytitanium phthalocyanine and has a charge mobility of 7.0 × 10 ⁻⁷ to
An electrophotographic photosensitive member having a ^{density of} 2.0 × 10 ⁻⁵ cm ² / V · s. 22. The electric field intensity of the electrophotographic apparatus is 3.5.
The electrophotographic photoreceptor according to claim 21, wherein the electrophotographic photoreceptor has a voltage of not more than × 10 ⁵ V / cm. 23. An electrophotographic apparatus having an image resolution of 12
The electrophotographic photoreceptor according to claim 21 or 22, wherein the electrophotographic photoreceptor has a resolution of 00 dpi or more. 24. The electrophotographic photosensitive member according to claim 21, wherein a process speed of the electrophotographic apparatus is 200 mm / s or less. 25. A first transfer means for transferring the toner image on the electrophotographic photosensitive member to an intermediate transfer member, wherein the transfer means of the electrophotographic apparatus transfers the toner image on the intermediate transfer member to the transfer material. And a second transfer means for performing the transfer.
The electrophotographic photosensitive member according to any one of the above. 26. The electrophotographic photosensitive member according to claim 21, wherein the photosensitive layer has a charge generating layer containing a charge generating substance and a charge transporting layer containing a charge transporting substance. 27. The electrophotographic photosensitive member according to claim 26, wherein the charge transport layer is a surface layer of the electrophotographic photosensitive member. 28. The charge transport layer having a thickness of 25 to 28 μm.
28. The electrophotographic photosensitive member according to claim 26, wherein m is m. 29. The electrophotographic photosensitive member according to claim 26, wherein the content of the charge transport material is 42 to 46% by mass based on the total mass of the charge transport layer. 30. A charge mobility of 1.5 × 10 ^{−6 to} 6.
The electrophotographic photosensitive member according to any one of claims 21 to 29 5 × is ^{10 -6 cm 2 / V · s} .