JP2007164008A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus with which high durability and high definition image formation is possible by suppressing the residual potential rise in repetitive use of a photoreceptor in order to form the image having the high durability and high definition, and an image forming method. <P>SOLUTION: The image forming apparatus has at least an electrostatic latent image carrier, an electrostatic latent image forming means on the electrostatic latent image carrier, a developing means, a transfer means, a fixing means, and a destaticizing means, in which the destaticizing means irradiates light of shorter wavelength than 500 nm, the electrostatic latent image carrier has a support and a photosensitive layer consisting of at least a charge generating layer and a charge transfer layer on the substrate, has further a protective layer on the photosensitive layer and contains an organic charge generating material in the charge generating layer and the protective layer is a diamond-like carbon and/or amorphous carbon structure containing hydrogen. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, an electrostatic latent image carrier (hereinafter sometimes referred to as “electrophotographic photosensitive member”, “photosensitive member”, or “photoconductive insulator”) used in an image forming apparatus is at least a charge generation layer. The present invention relates to an image forming apparatus and an image forming method having a photosensitive layer comprising a charge transport layer and an organic charge generating material in the charge generating layer.

  In recent years, there has been a remarkable development of information processing system machines using electrophotography. In particular, an optical printer that converts information into a digital signal and records information by light is markedly improved in print quality and reliability. This digital recording technique is applied not only to printers but also to ordinary copying machines, and so-called digital copying machines have been developed. In addition, since a variety of information processing functions are added to a conventional copying machine equipped with this digital recording technology for analog copying, the demand is expected to increase further in the future. Furthermore, with the spread of personal computers and the improvement in performance, the progress of digital color printers for performing color output of images and documents is rapidly progressing.

Most of such digital image forming apparatuses employ negative / positive development. This is because most of the images (originals) output by the conventional image forming apparatus are centered on characters, and the writing rate is low (about 5 to 10%) with respect to the output image (paper). to cause.
It can be said that the conversion from analog to digital has shifted from positive-positive development to negative-positive development. The big difference is that the entire surface of the document was irradiated with light and this was irradiated onto the photoconductor. There is a change in writing only information such as characters on the photosensitive member. Since the writing rate is low as described above, the output time of the light source is reduced to 1/10 if only the original information portion (about 10% or less of the whole) is used in consideration of the life of the writing light source. Is making use of.

  In an image forming apparatus using negative / positive development, the surface charge of the electrostatic latent image carrier remains in a portion (non-image portion, background portion) that is not written by a writing light source even after development and transfer. In some cases, there is an influence on the next charging, and static elimination is performed. For static elimination, light is used to generate photocarriers to cancel surface charges (photo static elimination), a method in which a conductive brush or the like is brought into contact with the photoconductor to leak charges, or a reverse bias is applied. A method of canceling the surface charge is used.

  In recent years, image forming apparatuses have been improved in image quality and color, and relatively high-definition writing and development have become possible, and information (originals) input to the image forming apparatus has changed somewhat. As described above, characters have mainly been used in past manuscripts, but photographic images, colored pictures, graphs, and the like have been input. When such various patterns of input signals exist, the next image formation may be affected unless the history of the previous cycle in image formation is erased. In many cases, an abnormal image called an afterimage is generated. The afterimage has already been formed in a non-uniform state when the photosensitive member is charged during the image forming process, and writing is performed uniformly over the entire area of the photosensitive member. (Especially halftone) The original charged potential after writing is almost uniform, but the history of the charged state of the photosensitive member before charging is left, so that the charge distribution becomes uneven. In this state, an electrostatic latent image is formed, and when this is developed by the developing unit, non-uniform development is performed, and the latent image formed in the previous image forming cycle remains as it is. It is what produces.

There are two reasons for this. One is that image formation has become very fast, so the capacity (charging ability) of the charger tends to be insufficient, and if the surface charge of the photoconductor before charging is not uniform, the history is picked up at the next charging. This is because it is impossible to ensure uniform charge. The other is that the use of the charging roller has increased due to the compactness of the image forming apparatus or tandemization by colorization. The charging roller causes a discharge phenomenon with the photoconductor and charges the surface of the photoconductor due to a bias difference between the two, but if the surface charge on the photoconductor before charging is non-uniform, the history will be recorded at the next charging. Will leave.
Therefore, the key is how to uniformize the surface potential (surface charge) of the photoreceptor before charging, and the charge removal process has played a very important role in improving image quality.

Among the static elimination methods described above, methods other than the optical static elimination have the following problems. The method of charge leakage using a conductive brush or the like requires a member that makes contact with the surface of the photoconductor, and wear of the photoconductor and the contact member occurs, so that high durability cannot be desired. In addition, the effect of the charge leakage method may be reduced due to contamination of the surface of the photoreceptor or the contact member. Further, when the speed is increased, a sufficient effect cannot be expected in consideration of the charge transfer time.
In the method of applying the reverse bias, uniformization is not sufficiently performed when the bias application condition is too weak, and when the bias application condition is too strong, the surface of the photoreceptor is reversely charged. Since a normal photoconductor can move only a positive charge, it cannot be canceled when the surface is charged with a positive charge. Accordingly, when negative charging is performed at the next charging, the positive charge is first canceled and then negative charging is performed. This further creates a shortage of charger capacity. Further, when positively charged, it becomes easy to form a trap in the photosensitive layer, and it becomes easy to generate a residual potential of the photosensitive member, and as a result, the life of the photosensitive member is shortened.

From the above, it can be said that the use of optical static elimination is the best choice at the present time for the static elimination process in the image forming apparatus. As described above, in recent years, digital image forming apparatuses have become mainstream, and for the reasons described above, negative / positive development is used as a developing method used at that time. Compared with the case of positive / positive development in the analog method used conventionally, the meaning in charge removal is very different.
That is, in the positive / positive development, in the photostatic discharge after transfer, the entire surface of the photosensitive member is usually irradiated with light, but only the area corresponding to the writing portion of characters or the like is substantially discharged. For this reason, the area is at most about 10% with respect to the entire area of the photosensitive member.

On the other hand, in negative / positive development, the non-exposed portion of the photoconductor (the portion where writing is not performed) is substantially neutralized, so if the document is the same as the above, it is close to 90% of the total area of the photoconductor. The area will be substantially neutralized. As used herein, “substantially charge removal” means that the photoconductor has a surface charge at the place where photostatic discharge is performed, and light irradiation of the charge removal member generates photocarriers inside the photoconductor, thereby This means that the surface charge of the photoreceptor is canceled out.
In other words, the positive / positive development and the negative / positive development that have been used in the past mean that the rate of canceling the surface charge of the photoconductor is completely different (reverse history). -The effect of static elimination is different by at least 10 times compared to the case of positive development. However, studies on the influence (especially the neutralization light wavelength, etc.) in the neutralization process on the photosensitive member have not been conducted so much, and the actual situation is that they have been used as before.

  As a technique related to a charge removal member, Patent Document 1 or Patent Document 2 irradiates an appropriate charge removal light including light having a short wavelength in an image forming apparatus using an inorganic photoreceptor (Se series, a-Si). Therefore, there is a description that light fatigue and charging fatigue can be prevented. However, the photoconductor used in Patent Document 1 or Patent Document 2 is an inorganic photoconductor, and the photocarrier generation mechanism is essentially different from a photoconductor using an organic charge generating material as described later. For this reason, inorganic technology (photo static elimination) cannot be applied to an organic photoreceptor as it is. Further, the development method used is the age of positive / positive development, and the degree of influence of light neutralization is completely different from that of negative / positive development. Further, the wavelength of the static elimination light includes wavelength light in a region of 500 nm or more. As a result of performing an experiment by applying the technique of Patent Document 1 or Patent Document 2, the effect of suppressing the increase in the residual potential was not sufficient.

  In Patent Document 3, exposure is performed at a wavelength that approximately matches the intrinsic photosensitive wavelength of a dye-sensitized photoconductor, in other words, by performing neutralization using a wavelength in a region where no sensitizing dye is absorbed, There is a description that can be removed. However, the original material (for example, polyvinyl carbazole) or the like of a photosensitized photoreceptor subjected to dye sensitization has no absorption in the visible range, and is sensitized with a dye having absorption in the visible range. Therefore, in the above technique, the dye is not absorbed and the charge is removed in a wavelength region having absorption in polyvinyl carbazole. In this case, the photocarrier generation efficiency in this wavelength band is low, and not only charge removal cannot be performed efficiently, but also photodegradation of polyvinyl carbazole, etc., which may not necessarily be an effective means. . Further, the development method used is the age of positive / positive development, and the degree of influence of light neutralization is completely different from that of negative / positive development. For this reason, when it is used for negative / positive development which is the subject of the present invention, the effect is not sufficient.

  In Patent Document 4, due to light fatigue, a photoconductor having photosensitivity at a long wavelength and having low sensitivity or no substantial photosensitivity on the short wavelength side is eliminated by using short wavelength light. There is a description that suppresses a decrease in sensitivity. However, in a relatively high-speed image forming apparatus, when neutralization is performed with light in a region with low sensitivity or substantially no photosensitivity, the neutralization function is insufficient and abnormal images cannot be suppressed. Cases arise. It is important to have sufficient photosensitivity for the static elimination light, and the technique of Patent Document 4 cannot cope with current image forming measures. In Patent Document 4, the neutralization wavelength is not specified.

Patent Document 5 and Patent Document 6 disclose that a positively charged photoconductor having a charge generation layer laminated on a charge transport layer is discharged by irradiating light with a wavelength of 620 nm or less to reduce the residual potential. There is a description. The wavelength of the static elimination light includes wavelength light in the region of 500 nm or more. As a result of conducting an experiment by applying the technique of Patent Document 5 or 6, the effect of suppressing the increase in residual potential was not sufficient.
Patent Document 7 describes that neutralization is performed by simultaneously irradiating two types of light emitting diodes, thereby preventing an increase in residual potential under high temperature and high humidity. The wavelength of the static elimination light includes wavelength light in the region of 500 nm or more. As a result of conducting an experiment by applying the technique of Patent Document 7, the effect of suppressing the increase in residual potential was not sufficient.
Patent Document 8 describes that, in the charge removal of a single-layer photoreceptor containing an organic pigment, the charge removal is efficiently performed by irradiating light in a range including a wavelength region equal to or greater than the half-value width of the maximum absorbance of the photosensitive layer. is there. Usually, a practical organic pigment has an absorption peak in the visible region, and therefore, the technique of Patent Document 8 cannot obtain a sufficient effect of suppressing the increase in residual potential.

In Patent Document 9, by selecting a wavelength at which the sensitivity of the photoconductor at the charge eliminating wavelength is higher than the sensitivity of the photoconductor at the writing light and using it for the charge eliminating light, it is possible to reduce the residual potential and suppress the occurrence of ghost. There is a statement to that effect. In this technique, the charge removal wavelength differs depending on the photosensitive material used, and the charge removal wavelength cannot be specified. In addition, organic pigments usually have an absorption peak in the visible region, and a spectral sensitivity peak is also present in the visible region. For this reason, in the technique of patent document 9, the static elimination technique by the wavelength of 500 nm or less is not produced.
Patent Document 10 describes that light of a wavelength with a relatively low spectral absorptivity of a photoconductor is irradiated in the charge removal of an image forming apparatus using a charge generation material dispersion type (single-layer photoconductor) photoconductor. There is. This technique is performed in order to remove residual charges generated in the bulk of the photosensitive layer when the single-layer photosensitive member is repeatedly used. That is, in the case of a single-layer photoconductor, the charge generating material is uniformly dispersed in the bulk, and the irradiation light is absorbed near the surface of the photosensitive layer at a wavelength having a high absorption rate. The high resolution of a single-layer photoconductor utilizes this phenomenon, and writing light is used to reduce the irradiation energy by using a wavelength with a high absorption rate of the photosensitive layer, and to generate optical carriers only near the surface of the photosensitive layer. generate. For this reason, the movement distance of the charge having the opposite polarity to the polarity charged on the surface of the photosensitive member is small, and the diffusion due to the Coulomb repulsion is prevented by reducing the movement distance of the charge. On the other hand, since the irradiation light hardly reaches the inside of the bulk, when the charge having the same polarity as that charged on the surface of the photosensitive member is trapped in the photosensitive layer bulk and becomes a residual potential, it can be canceled. I can't. For this reason, in the static elimination light, light with a wavelength that penetrates deep into the bulk is used to cancel the light by generating optical carriers in the deep part of the bulk (near the electrode, near the center of the photosensitive layer, etc.). To do.

On the other hand, the charge generation layer of the laminated photoreceptor is very thin, unlike the single-layer photosensitive layer. Further, the absorptance with respect to the writing light is 90% or less even at the maximum absorption wavelength (in other words, the writing light is transmitted through the charge generation layer by 10% or more). For this reason, even if the wavelength of the writing light is different, there is no change in the essence that charge generation occurs in the entire charge generation layer bulk. Therefore, in the case of the laminated photoconductor, the effect described in Patent Document 10 does not occur.
Patent Document 11 describes that the phthalocyanine compound is subjected to light irradiation with respect to the Soret band to perform static elimination. In addition, this publication describes that a fluorescent lamp is used as a static elimination light source in order to realize this.
Further, Patent Document 12 describes that a photoreceptor containing a phthalocyanine compound is subjected to charge removal with a fluorescent lamp.

FIG. 1 shows a spectral emission spectrum of light from a fluorescent lamp. Fluorescent lamps contain several bright lines, but in addition to this, there is a large light emission from 500 to 650 nm. Since the light irradiation amount (light emission amount) depends on the area of FIG. 1, the light of the fluorescent lamp irradiated on the photosensitive member is mainly light in the above wavelength range (500 to 650 nm). It will be irradiated.
In Patent Documents 11 and 12, charge removal by 680 nm red LED light and charge removal by fluorescent lamp irradiation are compared. From the spectrum of FIG. 1, the comparison between the two means that the charge removal by the red LED light of 680 nm and the charge removal by the light emission from 500 to 650 nm are compared. Since the light corresponding to the phthalocyanine Sore band is not zero, it is true that the Sore band is irradiated with light. It will be big.

Under such circumstances, the printer and the copying machine are required to have higher image quality and higher durability, including colorization. There are two problems in improving the image quality in a digital machine. One is how to uniformly form an electrostatic latent image with minute dots, and the other is how to reduce various abnormal images. In terms of increasing durability, extending the life of the photoreceptor is the most effective method.
There are various approaches to solve these problems, but what can be said in common to both is how to reduce the deterioration due to electrostatic fatigue of the photoreceptor used in these image forming apparatuses. Specifically, it is how to suppress an increase in residual potential (exposure portion potential) during repeated use.

As a countermeasure for increasing the residual potential, the development so far has been performed by devising the design (prescription, configuration, etc.) of the photoreceptor. However, the electrostatic fatigue of the photoreceptor varies greatly depending on the photoreceptor formulation or process conditions, and when considered from the development side of the photoreceptor, it is necessary to cope with each process condition. Under such circumstances, little study has been made on the electrostatic fatigue of the photoreceptor from the process conditions.
The technology of the protective layer according to claim 1 is described in Patent Documents 13 and 14. However, when used for recent negative / positive development and aiming for very high durability, the process conditions to be used are not established, and the superiority of the material is not necessarily fully drawn out. There wasn't.

JP 60-88981 A JP-A-62-87981 JP-A 61-36784 JP-A-62-38491 JP-A-1-217490 JP-A-1-274186 JP-A-4-17489 Japanese Patent No. 3460285 JP 2002-287382 A Japanese Patent Laying-Open No. 2005-31110 JP 2004-45996 A JP 2004-45997 A Japanese Patent No. 3409107 Japanese Patent No. 3350833

An object of the present invention is to solve the conventional problems and achieve the following objects.
That is, the present invention provides an image forming apparatus and an image forming method capable of forming a highly durable and high-definition image by suppressing an increase in residual potential due to repeated use of the photoreceptor in order to form a highly durable and high-definition image. The purpose is to provide.

The inventors of the present invention have examined how the process conditions influence the electrostatic fatigue of the photoreceptor, particularly the increase in residual potential. The examination method is as follows.
A state in which only charging, writing, and static elimination are applied with development, transfer, and cleaning members removed so as not to affect the shape and physical properties other than the electrostatic characteristics of the photoreceptor as much as possible in repeated use in an image forming apparatus. Then, an electrostatic fatigue test of the photoreceptor was performed.
(I) The writing rate by the writing light was changed, and the amount of charge passing through the photoreceptor was measured.
(Ii) The surface charge was erased only by static elimination light without writing, and the passing charge amount of the photoreceptor was measured.
At this time, the following knowledge was obtained by evaluating the residual potential of the photoconductor under various conditions (i) and (ii).
(1) The increase in the residual potential of the photoconductor depends on the amount of charge passing through the photoconductor. Even when the writing rate is changed, the amount of increase in residual potential is evenly arranged by arranging the amount of passing charges.
(2) The passing charge amount of the photoreceptor depends on the light irradiation amount in one cycle of image formation. Regardless of writing and static elimination, it depends on the light irradiation amount (more precisely, the light absorption amount of the photosensitive member).
(3) In the case of negative / positive development, most of the light irradiation amount is given by light neutralization.

Further, an experiment similar to the above was performed by attaching a transfer member so that a reverse bias could be applied to the photoreceptor before the charge removal step. The surface potential of the photoconductor before neutralization can be measured and the reverse bias is changed so that the surface potential of the photoconductor before neutralization becomes substantially the same as the surface potential after neutralization in the experiments (1) to (3). The reverse bias can be applied under such conditions.
When the electrostatic fatigue test was carried out in this state, the amount of increase in the residual potential of the photoconductor became very small and became a magnitude depending on the writing rate, and the influence of static elimination did not appear at all.

From the above, the following can be said.
(4) If the photoreceptor surface potential is lowered before static elimination, the residual potential is unlikely to increase. In other words, if the surface potential of the photosensitive member is low at the time of charge removal, irradiation with charge removal light does not contribute to an increase in residual potential.
(5) Even when a reverse bias is applied and the surface potential of the photoconductor is lowered before static elimination, the amount of increase in residual potential can be organized by the amount of charge passing through the photoconductor as in (1) above.
From (1) to (5), although the increase in the residual potential depends on the amount of charge passing through the photoconductor, most of it is generated in the static elimination process, and how to control the static elimination process depends on the increase in the residual potential. One key to control.

The passing charge amount shown in (1) is the passing charge amount per unit surface area of the photoreceptor in one cycle of image formation, and depends on the amount of photocarrier generated. Therefore, the image forming conditions depend on the charging potential (applied electric field strength to the photosensitive member), the exposure amount, the exposure area, the electrostatic capacitance (film thickness) of the photosensitive member, the carrier generation efficiency, and the like. However, in the target image forming apparatus, these items cannot be changed so much.
For example, greatly changing the charging potential brings about the following changes. When the charging potential is greatly increased, the hazard to the photoreceptor increases. In the case of a large decrease, the background potential (photosensitive member charging potential-developing bias) becomes small, or the developing potential (developing bias-photosensitive member exposure portion potential) becomes small, and image forming conditions (especially developing conditions). Becomes very narrow and the margin of the system becomes small.
Changing the exposure amount greatly brings about the following changes. When the exposure amount is reduced, there are cases where the image density becomes insufficient or the contrast cannot be obtained. On the other hand, when the exposure amount is increased, a phenomenon that the dots are crushed occurs.

The electrostatic capacity (film thickness) and carrier generation efficiency of the photoconductor do not change significantly unless the photoconductor material itself is changed significantly, but it is used for current high-speed, high-durability, and high-stability image forming devices. There are limits to the main materials (charge generating substances and charge transporting substances) that can be produced, and it is extremely difficult to change them to completely different materials.
Accordingly, the passing charge amount of the photoconductor mounted on the target image forming apparatus does not change significantly, and greatly depends on the light irradiation amount.

However, the light irradiation amount referred to here is the light irradiation amount to the photosensitive member in one cycle of image formation (charging, writing, developing, transferring, discharging). The image formation includes a fixing step, but is not directly in contact with the photoconductor, and therefore is omitted from the description here. In other words, it can be seen that the light irradiation to the photoconductor consists of two types of writing light and static elimination light.
Generally, an image forming apparatus that performs digital writing currently uses negative / positive development. This is due to the fact that most of the writing rate of an actual document is 10% or less, and the purpose is to reduce stress on the writing light source. However, from the viewpoint of the photoconductor side, if the surface potential of the photoconductor is not canceled (smoothed) before the next image forming cycle, it will be affected at the time of the next charging. The surface potential of the photoreceptor is reduced as much as possible before charging in the next step.

As described above, since the writing rate is about 10%, 90% or more of the surface of the photoconductor enters the charge removal process with surface charge on it. Here, the remaining charge is erased by irradiating the surface potential of the photoreceptor remaining after the transfer with a charge-removing light and generating a photocarrier. That is, 90% or more of the charge passing through the photoreceptor generated in one cycle of the image forming process is generated in the static eliminating process.
Up to this point, this is the normal state of an image forming apparatus using negative / positive development, and basically all negative / positive images are output except when only originals that are continuously written on the entire surface are output. This is true for image forming apparatuses that use development. However, as described above, the actual situation is that the analysis from the process side regarding the electrostatic fatigue of the photoreceptor has not been performed so much.

The light transmission property of the charge transport layer or the protective layer is different between the case of the static elimination light and the case of the writing light. For example, when the charge transport layer or the protective layer absorbs part of the writing light, there is a problem that the photosensitivity itself of the photoreceptor deteriorates. Further, in the case where fluorescence or phosphorescence is generated by the absorbed writing light, the charge generation layer absorbs this and generates carriers. In such a case, although a decrease in photosensitivity can be prevented somewhat, there is a fatal defect that the image itself blurs because fluorescence and phosphorescence are not directional.
On the other hand, in the case of static elimination light, since the formation of the electrostatic latent image and the toner image has already been completed, the main aim is to equalize the photoreceptor surface potential in preparation for the next charging. In view of layout, the light irradiation time and the light irradiation amount can be set sufficiently longer than the case of writing light. For this reason, the decrease in the photosensitivity with respect to the static elimination light can be almost ignored. Even if fluorescence or phosphorescence is generated, if the surface potential of the photoreceptor can be made uniform as a result, the main purpose in the static elimination process is achieved. These points are decisively different from the invention related to writing.

The present inventor examined the control by process conditions for the increase in the residual potential (exposure portion potential) in the repeated use of the photoreceptor. As described above, the static elimination process in image formation has a great influence. Was revealed. Furthermore, examination was repeated regarding the conditions (mainly light wavelength) of static elimination light.
The neutralizing light exhibits its function as long as the photoconductor (charge generation layer) has a wavelength with absorption. In general, a light source such as an LED array or a fluorescent lamp is used to irradiate substantially uniform light in the longitudinal direction of the photoreceptor. In the past, fluorescent lamps have been mainly used, but have the following problems because they include light in an area where the charge transport layer or the protective layer absorbs light.
(1) Since a part of light is absorbed by the charge transport layer or the protective layer, there is a case where sufficient light does not reach the charge generation layer, and there is a case where the amount of light must be very large.
(2) As a result of the charge transport material contained in the charge transport layer or the protective layer absorbing the static elimination light, the charge transport material may deteriorate and affect the electrostatic characteristics of the photoreceptor.

In order to overcome such a problem, a red LED (having a wavelength on the order of 600 nm) has generally been used. At the wavelength of this red LED, normally used charge transport materials have no absorption, the above-mentioned two problems can be cleared, and many charge generation materials have a large absorption, so that the charge removal is carried out efficiently. In addition, the fact that the cost of the LED is relatively low is also a great advantage of using this member.
The present inventor questioned whether the neutralization by irradiating light of a relatively long wavelength such as the red LED is optimal for repeated use of the photoreceptor, and examined the wavelength dependence of the neutralization light. Specifically, various wavelengths were produced by combining a monochromatic laser beam or an appropriate light source and a filter, and studies were made on the increase in residual potential in repeated use of the photoreceptor.
As a result, it has been found that red static elimination, which has been considered to be good in the past, raises the residual potential rather than irradiating light with a shorter wavelength. Further, when looking closely at the wavelength dependence, it has been found that an increase in the residual potential can be significantly suppressed by performing static elimination with light having a wavelength shorter than 500 nm. In this experiment, the amount of charge passing through the photoconductor per unit time at the time of static elimination is adjusted, so the amount of static elimination light applied to the photoconductor is determined by the spectral absorption spectrum profile of the photoconductor (charge generation material). Although it changes, the light absorption amount of the photosensitive layer does not change. Therefore, it was understood that the above result was due to the influence of the wavelength dependency of the static elimination light.

Obtaining the above knowledge, the present inventors have completed the present invention.
Further, it has been found that the process-side control technique (means) in image formation can suppress the increase in the residual potential as described above, but the photoreceptor to be used has poor durability against electrostatic fatigue. And the effect is not fully demonstrated.
The inventor has found that by using a specific protective layer, it is possible to greatly control the deterioration of electrostatic characteristics in the repeated use of a photoreceptor using the protective layer.
As a result of intensive studies to solve the above problems, the present inventor has found that the electrostatic latent image carrier has a laminated photosensitive layer comprising at least a charge generation layer and a charge transport layer, and has a protective layer on the photosensitive layer. In the image forming apparatus, the protective layer has a diamond-like carbon and / or amorphous carbon structure containing hydrogen, and a light source having a wavelength shorter than 500 nm is used as a static elimination light source. It was found that the increase in residual potential at the time was suppressed, and that it was found that image formation with few abnormal images could be stably performed, and that the above problems could be solved.

The present invention is based on the above knowledge of the present inventor, and means for solving the above problems are as follows. That is,
(1) an electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and developing the electrostatic latent image with toner to make it visible Development means for forming an image, transfer means for transferring the visible image to a recording medium, fixing means for fixing the transferred image transferred to the recording medium, and static elimination for removing static charge from the electrostatic latent image carrier An image forming apparatus including at least a discharging unit that discharges light having a wavelength shorter than 500 nm, and the electrostatic latent image carrier is provided on the supporting member. A diamond-like carbon having at least a photosensitive layer comprising a charge generation layer and a charge transport layer, and further having a protective layer on the photosensitive layer, the charge generation layer containing an organic charge generation material, and the protective layer containing hydrogen. An image forming apparatus having an amorphous carbon structure.
(2) The image forming apparatus according to item (1), wherein the protective layer further contains at least one element selected from the group consisting of nitrogen, fluorine, phosphorus, chlorine and bromine.

(3) The image forming apparatus according to item (1) or (2), wherein the organic charge generating substance is an azo pigment represented by the following formula (I):
In the formula, Cp ₁ and Cp ₂ represent coupler residues. R ₂₀₁ and R ₂₀₂ each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a cyano group, and may be the same or different. Cp ₁ and Cp ₂ are represented by the following formula (II).
In the formula, R ₂₀₃ represents a hydrogen atom, an alkyl group, or an aryl group. _R204 , _R205 , _R206 , _R207 , and _R208 each represent a hydrogen atom, a nitro group, a cyano group, a halogen atom, a halogenated alkyl group, an alkyl group, an alkoxy group, a dialkylamino group, or a hydroxyl group; A group of atoms necessary for constituting a substituted or unsubstituted aromatic carbocyclic ring or a substituted or unsubstituted aromatic heterocyclic ring.

(4) The image forming apparatus according to item (3), wherein Cp ₁ and Cp ₂ of the azo pigment are different from each other.
(5) The organic charge generating substance has a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray of CuKα, and further 9.4 °, 9. It has major peaks at 6 ° and 24.0 °, and has a peak at 7.3 ° as the lowest angled diffraction peak. Between the peak at 7.3 ° and the peak at 9.4 ° The image forming apparatus according to item (1) or (2), wherein the image forming apparatus is a titanyl phthalocyanine crystal having no peak and further having no peak at 26.3 °.
(6) In the latent image carrier, the intermediate layer is provided between the support and the charge generation layer, and the intermediate layer includes a charge blocking layer and a moire preventing layer. The image forming apparatus according to any one of (5).
(7) The image forming apparatus according to (12), wherein the charge blocking layer is made of an insulating material and has a thickness of less than 2.0 μm and 0.3 μm or more.

(8) Item (6) or Item (7), wherein the moire preventing layer contains an inorganic pigment and a binder resin, and the volume ratio of the two is in the range of 1/1 to 3/1. The image forming apparatus according to any one of the above.
(9) The exposure light source wavelength used in the electrostatic latent image forming unit is a light source having a wavelength shorter than 450 nm, according to any one of (1) to (8), Image forming apparatus.
(10) Any of (1) to (9) above, comprising a plurality of image forming elements each having at least an electrostatic latent image carrier, an electrostatic latent image forming unit, a developing unit, a transfer unit, and a charge eliminating unit An image forming apparatus according to claim 1.
(11) The electrostatic latent image carrier and one or more means selected from an electrostatic latent image forming means, a developing means, a charge eliminating means, and a cleaning means are integrated, and a process cartridge that is detachable from the apparatus main body is mounted. The image forming apparatus according to any one of (1) to (10).

(12) an electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and developing the electrostatic latent image with toner to make it visible Development means for forming an image, transfer means for transferring the visible image to a recording medium, fixing means for fixing the transferred image transferred to the recording medium, and static elimination for removing static charge from the electrostatic latent image carrier An image forming apparatus including at least a discharging unit that discharges light having a wavelength shorter than 500 nm, and the electrostatic latent image carrier is provided on the supporting member. A diamond-like carbon having at least a photosensitive layer comprising a charge generation layer and a charge transport layer, and further having a protective layer on the photosensitive layer, the charge generation layer containing an organic charge generation material, and the protective layer containing hydrogen. And / or a process car having an amorphous carbon structure Ridge.
(13) The process cartridge as described in (12) above, wherein the exposure light source wavelength used in the electrostatic latent image forming means is a light source having a wavelength shorter than 450 nm.

(14) an electrostatic latent image forming step of forming an electrostatic latent image on the electrostatic latent image carrier, a developing step of developing the electrostatic latent image with toner to form a visible image, An image forming method comprising at least a transfer step for transferring a visible image to a recording medium, a fixing step for fixing the transferred image transferred to the recording medium, and a static elimination step for eliminating static charges from the residual charge on the electrostatic latent image carrier. The static elimination step is a static elimination step of irradiating light having a wavelength shorter than 500 nm, and the electrostatic latent image carrier includes a support, and at least a charge generation layer and a charge transport layer on the support. A photosensitive layer comprising a photosensitive layer, a protective layer on the photosensitive layer, an organic charge generating material in the charge generating layer, and the protective layer having a diamond-like carbon and / or amorphous carbon structure containing hydrogen. There is provided an image forming method.
(15) The image forming method as described in (14) above, wherein the light source wavelength of the image writing light used in the electrostatic latent image forming step is a light source having a wavelength shorter than 450 nm.
(16) The image forming method according to any one of (14) or (15), comprising a plurality of image forming steps including at least an electrostatic latent image forming step, a developing step, a transfer step, and a charge eliminating step. .

According to the study of the present inventor, when the irradiation light is finely decomposed, the increase in the residual potential can be suppressed as the short wavelength light is irradiated, and when the long wavelength light (light of 500 nm or more) is mixed. The residual potential rise was observed according to the amount of long wavelength light mixed. Therefore, the method described in Patent Document 1 is still insufficient as a technique for suppressing the increase in residual potential in consideration of high durability and high image quality.
Therefore, the neutralization light having a wavelength shorter than 500 nm as the neutralization light in the present invention indicates that the light does not include light on the long wavelength side of 500 nm or longer (hereinafter referred to as the neutralization light of less than 500 nm). Is).
A detailed mechanism that can suppress an increase in residual potential in the repeated use of the photoreceptor by using charge removal light of less than 500 nm has not been clarified. At present, the mechanism is considered as follows.

FIG. 2 shows a photocarrier generation mechanism of an organic material (organic charge generation material). The photocarrier generation mechanisms of organic materials known so far are mostly based on a reaction consisting of two steps (photoexcitation → intermediate generation → free carrier generation) as shown in FIG. At this time, the organic charge generating material absorbs light and is excited to a higher excited state, but the formation of the intermediate occurs from a certain energy level. This constant energy level is the lowest excited singlet state (S ₁ ). When an energy (light having a long wavelength) smaller than that between the ground state (S ₀ ) and the lowest excited singlet state (S ₁ ) is irradiated, optical carriers are hardly generated.
On the other hand, when irradiated with energy (short wavelength light) larger than between the ground state (S ₀ ) and the lowest excited singlet state (S ₁ ), the energy level (S ^* ) higher than S _1. And is immediately relaxed to the S ₁ state, and an intermediate is formed from S ₁ . At this time, the energy corresponding to the energy difference between S ^* and S ₁ is thermally relaxed (shown as surplus energy in the figure).
This model is supported by the result that there is no wavelength dependency of the photocarrier generation efficiency of the organic photoreceptor.

When the electrophotographic photosensitive member is repeatedly used, the residual potential increases due to the positive and negative photocarriers generated by the generation of photocarriers due to the action of the electric field applied to the photosensitive member. In the case of a body, the negative charge is on the surface side of the photoreceptor). At this time, the optical carrier falls into a certain trap and forms a residual potential. Since the depth of this trap is larger than the activation energy given by room temperature, it cannot be detrapped under normal use and is accumulated as a residual potential.
By the way, when most of the optical carriers generated in one cycle of image formation are generated by static elimination light having a wavelength shorter than 500 nm as in the present invention, the state of large surplus energy shown in FIG. 2 is repeated. For this reason, it is thought that this surplus energy can suppress a rise in residual potential by acting on detrapping.

FIG. 3 shows a schematic diagram of a photocarrier generation mechanism of an inorganic photoconductor. In general, in the case of an inorganic material (inorganic charge generation material), a band model is applied, so a model composed of a valence band and a conduction band as shown in FIG. 3 is submitted.
Electrons that have obtained energy corresponding to the band gap by photoexcitation can move freely in the valence band and exist as free carriers. In this case, the conduction band region is characterized by being directly ionized to become free carriers. Therefore, when energy larger than the energy gap is obtained as shown in FIG. 2, carrier generation efficiency (ion dissociation efficiency) is improved, but no surplus energy is generated. This point is greatly different from the photocarrier generation mechanism of the organic photoreceptor.
Such an inorganic model is supported by the result that the carrier generation efficiency of the inorganic photoconductor shows the wavelength dependence on the excitation light.

Considering the difference in the photocarrier generation mechanism between the organic photoconductor and the inorganic photoconductor, the difference in the effect on the charge elimination light wavelength in the present invention can be considered.
That is, in the photocarrier generation in the static elimination process as described above, in the case of an organic photoreceptor, the carrier generation amount with respect to the static elimination light wavelength does not change (the quantum efficiency is not wavelength dependent), but when one carrier is generated. The surplus energy has wavelength dependency. That is, the shorter the neutralization wavelength, the greater the amount of surplus energy generated inside the photoreceptor.
On the other hand, in the case of an inorganic photoconductor, the quantum efficiency depends on the wavelength. Therefore, the shorter the neutralization wavelength, the more carriers are generated, but no surplus energy is generated (the energy corresponding to the surplus energy is To be improved).
Therefore, when the neutralization light having a wavelength shorter than 500 nm is irradiated as in the present invention, the amount of generated carriers is not changed in the organic photoreceptor as compared with the conventional case where the neutralization in the visible light region is performed. However, a lot of surplus energy can be acquired. This surplus energy is used as activation energy for detrapping the charges trapped in the photosensitive layer.

On the other hand, in the case of an inorganic photoconductor, only the amount of carriers generated is increased as described above, and no surplus energy is generated. Therefore, the charges trapped in the photosensitive layer cannot be detrapped. This is a major difference based on the difference in the material (carrier generation mechanism) constituting the photosensitive layer. For this reason, even if a short wavelength neutralization is performed with an inorganic photoconductor, the effect as in the present invention cannot be obtained, and even if there is a similar configuration, the idea, purpose, and effect thereof are Is completely different.
In order to sufficiently exhibit such an effect, it is necessary that the discharge light sufficiently reaches at least the charge generation layer of the photoreceptor. For this purpose, it is necessary that the charge transport layer and the protective layer installed on the upper layer of the charge generation layer sufficiently transmit the static elimination light of less than 500 nm. Moreover, even if it is the structure which permeate | transmits light less than 500 nm, if the carrier transport function is not enough, the stability of the electrostatic property of the photoreceptor in repeated use cannot be ensured.

For this reason, the characteristics required for the protective layer used in the present invention are as follows: (1) a sufficient removal of static elimination light of less than 500 nm in a state in which the protective layer is formed; and (2) a charge transport layer and (3) exhibiting stability as a material in repeated use of the photoreceptor; (3) being capable of smoothly injecting photocarriers in the charge transport layer; Specifically, it is resistant to an oxidizing gas generated by the charging means, and is stable even for a long period of time.
It is necessary to select a material from such a viewpoint, and the present inventor has a structure containing a charge transport material and at least one selected from an inorganic pigment and a metal oxide having a specific resistance of 10 ¹⁰ Ω · cm or more as a protective layer. As a result, it was found that the above conditions were satisfied, and the present invention was completed.

  According to the present invention, it is an image forming apparatus that can solve various problems in the prior art and can perform image formation with high durability and high image quality, and has at least a laminated photosensitive layer and a protective layer comprising a charge generation layer and a charge transport layer. In the electrostatic latent image carrier, the charge generation layer contains an organic charge generation substance, and the protective layer has a diamond-like carbon and / or amorphous carbon structure containing hydrogen, and the neutralization light source has a wavelength shorter than 500 nm. The image forming apparatus using the light source. Accordingly, it is possible to provide an image forming apparatus and an image forming method capable of outputting a stable image with high durability and few abnormal images.

(Image forming apparatus and image forming method)
The image forming apparatus of the present invention comprises an organic charge generating material in a charge generating layer in an electrostatic latent image carrier having at least a laminated photosensitive layer comprising a charge generating layer and a charge transport layer and a protective layer, and the protective layer is a hydrogen layer. Containing an electrostatic latent image carrier having a diamond-like carbon and / or amorphous carbon structure, an electrostatic latent image forming unit, a developing unit, a transferring unit, a fixing unit, and a light source having a wavelength shorter than 500 nm And at least other means appropriately selected as necessary, for example, cleaning means, recycling means, control means, and the like.
The image forming method of the present invention comprises at least an electrostatic latent image forming step, a developing step, a transfer step, a static elimination step having a light source having a wavelength shorter than 500 nm, and a fixing step, and further if necessary. Other processes appropriately selected, for example, a cleaning process, a recycling process, a control process, and the like are included.
The image forming method of the present invention can be preferably carried out by the image forming apparatus of the present invention, the electrostatic latent image forming step can be performed by the electrostatic latent image forming means, and the developing step is the developing The transfer step can be performed by the transfer unit, the neutralization step can be performed by the neutralization unit, the fixing step can be performed by the fixing unit, and the other steps. Can be performed by the other means.

The image forming apparatus according to the present invention includes an electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and the electrostatic latent image using toner. Developing means for forming a visible image by development, transfer means for transferring the visible image to a recording medium, charge eliminating means for removing charges remaining on the electrostatic latent image carrier, and transfer to the recording medium At least a fixing unit for fixing the transferred image, and the static eliminator irradiates the electrostatic latent image carrier with static elimination light by a light source having a light source having a wavelength shorter than 500 nm.
-Electrostatic latent image carrier-
As the electrostatic latent image carrier, the charge generation layer contains an organic charge generation material, and the protective layer has charge transport with at least one selected from inorganic pigments and metal oxides having a specific resistance of 10 ¹⁰ Ω · cm or more. There are no particular restrictions on the material, shape, structure, size, etc., except that the inclusion of a substance is an essential requirement, and it can be appropriately selected from known ones. As the support, a conductive support having conductivity is preferable.

Next, the electrophotographic photosensitive member used in the present invention will be described in detail with reference to the drawings.
FIG. 4 is a cross-sectional view showing a configuration example of the electrophotographic photosensitive member used in the present invention. On the support (31), a charge generation layer (35 having at least an organic charge generation material as a main component as a charge generation material). ) And a charge transport layer (37) mainly composed of a charge transport material, and further, a protective layer (41) having a diamond-like carbon and / or amorphous carbon structure containing hydrogen on the charge transport layer. The structure which laminated | stacked is taken.
FIG. 5 is a cross-sectional view showing another structural example of the electrophotographic photosensitive member used in the present invention. On the support (31), an intermediate layer (39) and at least an organic charge generating material as a charge generating material are provided. A charge generation layer (35) having a main component and a charge transport layer (37) having a charge transport material as a main component are laminated, and diamond-like carbon and / or amorphous containing hydrogen on the charge transport layer. The protective layer (41) having a carbon structure is laminated.
In FIG. 6, the intermediate layer (39) is composed of a charge blocking layer (43) and a moire prevention layer (45), and a charge generation layer (35 having at least an organic charge generation material as a main component as a charge generation material on the intermediate layer. ) And a charge transport layer (37) mainly composed of a charge transport material, and further, a protective layer (41) having a diamond-like carbon and / or amorphous carbon structure containing hydrogen on the charge transport layer. The structure which laminated | stacked is taken.

Examples of the conductive support 31 include those having a volume resistance of 10 ¹⁰ Ω · cm or less, for example, metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, indium oxide, etc. The metal oxides of the above are coated with film or cylindrical plastic or paper by vapor deposition or sputtering, or a plate of aluminum, aluminum alloy, nickel, stainless steel, etc. and the like by extrusion, drawing, etc. After pipe formation, surface treatment pipes such as cutting, superfinishing, and polishing can be used. Endless nickel belts and endless stainless steel belts can also be used as the conductive support.
In addition, the conductive support dispersed in a suitable binder resin on the support can be used as the conductive support of the present invention. Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc and silver, or metal oxide powder such as conductive tin oxide and ITO. It is done. The binder resin used at the same time is polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer. , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing and coating these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, and toluene.

Furthermore, it is electrically conductive by a heat-shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, and Teflon (registered trademark) on a suitable cylindrical substrate. Those provided with a conductive layer can also be used favorably as the conductive support of the present invention.
Of these, a cylindrical support made of aluminum that can be easily subjected to the anodic oxide film treatment can be most preferably used. As used herein, aluminum includes both pure aluminum and aluminum alloys. Specifically, JIS 1000 series, 3000 series, 6000 series aluminum or aluminum alloy is most suitable. The anodized film is obtained by anodizing various metals and various alloys in an electrolyte solution. Among them, a film called anodized aluminum or an aluminum alloy that has been anodized in an electrolyte solution is used in the present invention. Is most suitable for. In particular, it is excellent in preventing point defects (black spots, background stains) that occur when used in reversal development (negative and positive development).

The anodizing treatment is performed in an acidic bath such as chromic acid, sulfuric acid, oxalic acid, phosphoric acid, boric acid, sulfamic acid. Of these, treatment with a sulfuric acid bath is most suitable. For example, sulfuric acid concentration: 10 to 20%, bath temperature: 5 to 25 ° C., current density: 1 to 4 A / dm ² , electrolytic voltage: 5 to 30 V, treatment time: treatment in the range of about 5 to 60 minutes However, the present invention is not limited to this. Since the anodic oxide film produced in this way is porous and has high insulation, the surface is very unstable. For this reason, there is a change with time after fabrication, and the physical property value of the anodized film is likely to change. In order to avoid this, it is preferable to further seal the anodized film. Examples of the sealing treatment include a method of immersing the anodized film in an aqueous solution containing nickel fluoride and nickel acetate, a method of immersing the anodized film in boiling water, and a method of treating with pressurized steam. Among these, the method of immersing in the aqueous solution containing nickel acetate is the most preferable. Subsequent to the sealing treatment, the anodic oxide film is washed. The main purpose of this is to remove excess metal salts and the like attached by the sealing treatment. If this remains excessively on the surface of the support (anodized film), it not only adversely affects the quality of the coating film formed on this surface, but also generally low resistance components remain, resulting in the occurrence of soiling. It can also be a cause. Cleaning may be performed with pure water only once, but usually, multistage cleaning is performed. At this time, it is preferable that the final cleaning liquid is as clean (deionized) as possible. Moreover, it is preferable to perform physical rubbing cleaning with a contact member in one of the multi-stage cleaning processes. The thickness of the anodized film formed as described above is preferably about 5 to 15 μm. If it is thinner than 5 μm, the effect of the barrier property as an anodic oxide film is not sufficient, and if it is thicker than 15 μm, the time constant as an electrode becomes too large, resulting in the generation of residual potential and the response of the photoreceptor. There is a case.

Next, the intermediate layer (39) will be described. The intermediate layer generally contains a resin as a main component, but these resins are preferably resins having a high solvent resistance with respect to a general organic solvent in consideration of applying a photosensitive layer thereon with a solvent. . Examples of such resins include water-soluble resins such as polyvinyl alcohol, casein, and sodium polyacrylate, alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon, polyurethane, melamine resin, phenol resin, alkyd-melamine resin, and epoxy. Examples thereof include a curable resin that forms a three-dimensional network structure such as a resin. Further, a fine powder pigment of a metal oxide exemplified by titanium oxide, silica, alumina, zirconium oxide, tin oxide, indium oxide and the like may be added to the intermediate layer in order to prevent moire and reduce residual potential.
Among these, when titanium oxide is contained in the intermediate layer, the effect of the present invention becomes remarkable and can be used most effectively. In addition, when the intermediate layer containing titanium oxide is present in contact with the charge generation layer described below, the effect is most remarkable, and the photoreceptor structure is most appropriate.

These intermediate layers can be formed by using an appropriate solvent and coating method like the above-mentioned photosensitive layer. Furthermore, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, or the like can be used as the intermediate layer of the present invention. In addition, the intermediate layer of the present invention is provided with Al ₂ O ₃ by anodic oxidation, organic matter such as polyparaxylylene (parylene), SiO ₂ , SnO ₂ , TiO ₂ , ITO, CeO _2, etc. Those provided with an inorganic material by a vacuum thin film forming method can also be used favorably. In addition, known ones can be used. The thickness of the intermediate layer is suitably from 0 to 5 μm.
The intermediate layer (39) has a function of preventing injection of a reverse polarity charge induced on the electrode side when the photosensitive member is charged into the photosensitive layer, and a function of preventing moire generated when writing with coherent light such as laser light. It has at least two functions. A function separation type intermediate layer in which this function is separated into two or more layers is an effective means for the photoreceptor used in the present invention. The function-separated intermediate layer of the charge blocking layer (43) and the moire prevention layer (45) will be described below.

The charge blocking layer (43) is a layer having a function of preventing reverse polarity charges induced in the electrode (conductive support 31) during charging of the photosensitive member from being injected into the photosensitive layer from the support. In the case of negative charging, it has a function of preventing hole injection, and in the case of positive charging, it has a function of preventing electron injection. The charge blocking layer includes an anodized film typified by an aluminum oxide layer, an inorganic insulating layer typified by SiO, a layer formed from a glassy network of metal oxide, a layer made of polyphosphazene, an aminosilane reaction A layer made of a product, a layer made of an insulating binder resin, a layer made of a curable binder resin, and the like can be given. Among them, a layer composed of an insulating binder resin or a curable binder resin that can be formed by a wet coating method can be used favorably. Since the charge blocking layer is formed by laminating a moiré preventing layer and a photosensitive layer thereon, when these are provided by a wet coating method, the charge blocking layer must be composed of a material or a structure that does not attack the coating film by these coating solvents. Is essential.
Examples of binder resins that can be used include thermoplastic resins such as polyamide, polyester, vinyl chloride-vinyl acetate copolymer, and thermosetting resins such as active hydrogen (—OH group, —NH ₂ group, —NH group, etc.). A thermosetting resin obtained by thermally polymerizing a compound containing a plurality of (hydrogen) and a compound containing a plurality of isocyanate groups and / or a compound containing a plurality of epoxy groups can also be used. In this case, examples of the compound containing a plurality of active hydrogens include acrylic resins containing active hydrogen such as polyvinyl butyral, phenoxy resin, phenol resin, polyamide, polyester, polyethylene glycol, polypropylene glycol, polybutylene glycol, and hydroxyethyl methacrylate groups. System resin and the like. Examples of the compound containing a plurality of isocyanate groups include tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, and prepolymers thereof. Examples of the compound having a plurality of epoxy groups include bisphenol A type epoxy resin. can give.
Among these, polyamide is most preferably used from the viewpoint of film formability, environmental stability, solvent resistance, and the like.

In addition, a thermosetting resin obtained by thermally polymerizing an oil-free alkyd resin and an amino resin such as a butylated melamine resin, a polyurethane having an unsaturated bond, a resin having an unsaturated bond such as an unsaturated polyester, and thioxanthone A photocurable resin such as a combination with a photopolymerization initiator such as a methyl compound or methylbenzyl formate can also be used as the binder resin.
In addition, a conductive polymer having a rectifying property or an acceptor (donor) resin / compound may be added in accordance with the charging polarity to provide a function of suppressing charge injection from the substrate.
The film thickness of the charge blocking layer is 0.1 μm or more and less than 2.0 μm, preferably about 0.3 μm or more and less than 2.0 μm. When the charge blocking layer becomes thicker, the residual potential increases remarkably at low temperature and low humidity due to repeated charging and exposure, and when the film thickness is too thin, the blocking effect is reduced, and the charge blocking layer (43) Add chemicals, solvents, additives, curing accelerators, etc. necessary for curing (crosslinking) as necessary, and use conventional methods such as blade coating, dip coating, spray coating, beat coating, nozzle coating, etc. Formed on a substrate. After the coating, it is dried or cured by a curing process such as drying, heating, or light.

The moiré prevention layer (45) is a layer having a function of preventing the generation of a moiré image due to light interference inside the photosensitive layer when writing with coherent light such as laser light. Basically, it has a function of causing light scattering of the writing light. In order to exhibit such a function, it is effective that the anti-moire layer has a material having a large refractive index. In general, it comprises an inorganic pigment and a binder resin, and the inorganic pigment is dispersed in the binder resin. In particular, white pigments are effectively used among inorganic pigments, and for example, titanium oxide, calcium fluoride, calcium oxide, silicon oxide, magnesium oxide, aluminum oxide, and the like are favorably used. Among these, titanium oxide having a large hiding power can be most effectively used.
Even when the intermediate layer is composed of the charge blocking layer and the moire preventing layer, the effect of the present invention is most remarkably exhibited when the moire preventing layer contains titanium oxide. Further, when the moiré preventing layer containing titanium oxide is brought into contact with the charge generation layer, the effect is remarkably enhanced, and is the most effective photoconductor structure.
In addition, in the photoreceptor having the function separation type intermediate layer, the charge blocking layer prevents the charge injection from the support (31). Therefore, in the moire preventing layer, at least the charge charged on the photoreceptor surface is From the viewpoint of preventing residual potential, it is preferable to have a function of moving charges of the same polarity. For this reason, for example, in the case of a negatively charged type photoreceptor, it is desirable to impart electronic conductivity to the moire prevention layer, and the inorganic pigment to be used is one that has electron conductivity, or one that is conductive. It is desirable. Alternatively, the use of an electron conductive material (for example, an acceptor) or the like for the moire preventing layer makes the effect of the present invention more remarkable.

As the binder resin, the same resin as the charge blocking layer can be used. However, in consideration of laminating the photosensitive layer (charge generation layer 35, charge transport layer 37) on the moire prevention layer, the photosensitive layer (charge generation layer, It is important not to be affected by the coating solvent of the charge transport layer.
As the binder resin, a thermosetting resin is preferably used. In particular, alkyd / melamine resin mixtures are best used. At this time, the mixing ratio of alkyd / melamine resin is an important factor for determining the structure and characteristics of the moire prevention layer. A range in which the ratio (weight ratio) of both is 5/5 to 8/2 can be cited as a good range of the mixing ratio. If the melamine resin is richer than 5/5, volume shrinkage is increased during thermosetting, and coating film defects are likely to occur, or the residual potential of the photoreceptor is increased. Further, if the alkyd resin is richer than 8/2, it is effective in reducing the residual potential of the photoreceptor, but it is not desirable because the bulk resistance becomes too low and the soiling becomes worse.

In the anti-moire layer, the volume ratio between the inorganic pigment and the binder resin determines an important characteristic. For this reason, it is important that the volume ratio of the inorganic pigment to the binder resin is in the range of 1/1 to 3/1. When the volume ratio of the two is less than 1/1, not only the moire prevention ability is lowered, but there is a case where the increase of the residual potential in repeated use becomes large. On the other hand, in the region where the volume ratio exceeds 3/1, not only the binding ability of the binder resin is inferior, but also the surface property of the coating film is deteriorated, which may adversely affect the film forming property of the upper photosensitive layer. This effect can be a serious problem when the photosensitive layer is a laminated type and a thin layer such as a charge generation layer is formed. When the volume ratio exceeds 3/1, there is a case where the binder resin cannot cover the surface of the inorganic pigment. The direct contact with the charge generation material increases the probability of heat carrier generation, resulting in soiling. It may have an adverse effect on it.
Furthermore, by using two types of titanium oxides having different average particle diameters for the moire prevention layer, it is possible to improve the concealing power to the conductive substrate and suppress moire and to cause a pin that causes an abnormal image. The hole can be eliminated. For this purpose, it is important that the ratio of the average particle diameter (D) of the two types of titanium oxide used is within a certain range (0.2 <D2 / D1 ≦ 0.5). In the case of the particle size ratio outside the range specified in the present invention, that is, the ratio of the average particle size (D2) of the other titanium oxide (T2) to the average particle size (D1) of the titanium oxide (T1) having a large average particle size is When it is too small (0.2 ≧ D2 / D1), the activity on the surface of titanium oxide is increased, and the electrostatic stability of the electrophotographic photosensitive member is significantly impaired. Further, when the ratio of the average particle diameter of the other titanium oxide (T2) to the average particle diameter of one titanium oxide (T1) is too large (D2 / D1> 0.5), the hiding power to the conductive substrate is lowered. In addition, the suppression of moiré and abnormal images is reduced. The average particle size mentioned here is obtained from a particle size distribution measurement obtained when strong dispersion is performed in an aqueous system.

Further, the average particle size (D2) of titanium oxide (T2) having a smaller particle size is an important factor, and it is important that 0.05 μm <D2 <0.20 μm. When the thickness is 0.05 μm or less, the hiding power is reduced, and moire may be generated. On the other hand, when the thickness is 0.20 μm or more, the filling rate of the titanium oxide in the moire preventing layer is lowered, and the background dirt suppressing effect cannot be sufficiently exhibited.
The mixing ratio (weight ratio) of the two types of titanium oxide is also an important factor. When T2 / (T1 + T2) is smaller than 0.2, the filling rate of titanium oxide is not so large and the effect of suppressing soiling cannot be sufficiently exhibited. On the other hand, when it is larger than 0.8, the concealing power is reduced, and moire may be generated. Therefore, it is important that 0.2 ≦ T2 / (T1 + T2) ≦ 0.8.
The thickness of the moire preventing layer is 1 to 10 μm, preferably 2 to 5 μm. If the film thickness is less than 1 μm, the effect is small, and if it exceeds 10 μm, residual potential is accumulated, which is not desirable.

  The inorganic pigment is dispersed together with a solvent and a binder resin by a conventional method, for example, a ball mill, a sand mill, an attrier, etc., and if necessary, a chemical, a solvent, an additive, a curing accelerator, etc. necessary for curing (crosslinking) are added. In general, it is formed on the substrate by blade coating, dip coating, spray coating, beat coating, nozzle coating or the like. After the coating, it is dried or cured by a curing process such as drying, heating, or light.

Next, the photosensitive layer will be described. The photosensitive layer has a laminated structure of a charge generation layer (35) containing an organic charge generation material as a charge generation material and a charge transport layer (37) containing a charge transport material.
The charge generation layer (35) is a layer mainly composed of an organic charge generation material as a charge generation material. It is formed by dispersing the organic charge generating material in a suitable solvent together with a binder resin as necessary using a ball mill, attritor, sand mill, ultrasonic wave, etc., applying this onto a conductive support, and drying. The
As the binder resin used for the charge generation layer (35) as required, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, polysulfone, poly- N-vinyl carbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinyl pyridine, cellulose resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, etc. Can be given. The amount of the binder resin is suitably 0 to 500 parts by weight, preferably 10 to 300 parts by weight with respect to 100 parts by weight of the charge generating material.

  Examples of the solvent used here include isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, ligroin and the like. As a coating method for the coating solution, a dip coating method, spray coating, beat coating, nozzle coating, spinner coating, ring coating, or the like can be used. The film thickness of the charge generation layer (35) is suitably about 0.01 to 5 μm, preferably 0.1 to 2 μm.

An organic charge generation material can be used as the charge generation material.
A known material can be used as the organic charge generating substance. For example, phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having carbazole skeleton, azo pigments having triphenylamine skeleton, azo pigments having diphenylamine skeleton, dibenzothiophene skeleton Azo pigments having a fluorenone skeleton, azo pigments having an oxadiazole skeleton, azo pigments having a bis-stilbene skeleton, azo pigments having a distyryl oxadiazole skeleton, azo pigments having a distyrylcarbazole skeleton, perylene Pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzoquinone and naphthoquinone pigments, cyanine and azomethine pigments, Goido based pigments, and bisbenzimidazole pigments. These charge generation materials can be used alone or as a mixture of two or more.
Among these, azo pigments represented by the following formula (I) are effectively used. In particular, an asymmetric azo pigment in which Cp ₁ and Cp ₂ of the azo pigment are different from each other has high carrier generation efficiency and can be effectively used as the charge generation material of the present invention.

In the formula, Cp ₁ and Cp ₂ represent coupler residues. R ₂₀₁ and R ₂₀₂ each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a cyano group, and may be the same or different. Cp ₁ and Cp ₂ are represented by the following formula (II):
In the formula, R ₂₀₃ represents a hydrogen atom, an alkyl group such as a methyl group or an ethyl group, or an aryl group such as a phenyl group. R ₂₀₄ , R ₂₀₅ , R ₂₀₆ , R ₂₀₇ and R ₂₀₈ are each a hydrogen atom, a nitro group, a cyano group, a halogen atom such as fluorine, chlorine, bromine or iodine, a halogenated alkyl group such as a trifluoromethyl group, or methyl. Represents an alkyl group such as an ethyl group, an alkoxy group such as a methoxy group or an ethoxy group, a dialkylamino group or a hydroxyl group, and Z constitutes a substituted or unsubstituted aromatic carbocyclic ring or a substituted or unsubstituted aromatic heterocyclic ring Represents the atomic group necessary to

  In addition, titanyl phthalocyanine can be effectively used as the charge generating material of the present invention. In particular, a titanyl phthalocyanine crystal having a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray of CuKα, and has a maximum diffraction peak at 27.2 °. Further, it has major peaks at 9.4 °, 9.6 °, and 24.0 °, and has a peak at 7.3 ° as the lowest diffraction peak, and the peak at 7.3 ° A titanyl phthalocyanine crystal that does not have a peak between 9.4 ° and further has no peak at 26.3 ° has a large carrier generation efficiency and can be used effectively as a charge generating material of the present invention.

In the organic charge generating material contained in the electrophotographic photosensitive member of the present invention, the effect is expressed by making the particle size of the charge generating material finer, and the average particle size is 0.25 μm or less. Preferably, 0.2 μm or less is more preferable. The manufacturing method is shown below. A method for controlling the particle size of the charge generating material contained in the photosensitive layer is a method of removing coarse particles larger than 0.25 μm after dispersing the charge generating material.
The average particle size referred to here is a volume average particle size, and is determined with an ultracentrifugal automatic particle size distribution analyzer: CAPA-700 (manufactured by Horiba, Ltd.). At this time, the particle diameter (Median diameter) corresponding to 50% of the cumulative distribution was calculated. However, this method may not be able to detect a minute amount of coarse particles, and in order to obtain more details, it is important to directly observe the charge generating material powder or dispersion with an electron microscope and obtain the size. It is.

  As a result of further observation of the dispersion and examination of micro defects, the above phenomenon was understood as follows. Usually, in the method of measuring the average particle size, when an extremely large particle is present in several% or more, the presence can be detected, but it is about 1% or less of the whole. When the amount is too small, the measurement is below the detection limit. As a result, the presence of coarse particles is not detected only by measuring the average particle size, making it difficult to interpret the above minute defects.

7 and 8 show photographs observing the state of two types of dispersions in which only the dispersion time is changed with the dispersion conditions fixed. A photograph of a dispersion having a short dispersion time under the same conditions is shown in FIG. 7. Compared with FIG. 8 having a long dispersion time, it is observed that coarse particles remain. Black particles in FIG. 7 are coarse particles.
The average particle size and particle size distribution of these two types of dispersions were measured according to a known method using a commercially available particle size distribution measuring device (manufactured by Horiba: ultracentrifugal automatic particle size distribution measuring device, CAPA700). The result is shown in FIG. “A” in FIG. 9 corresponds to the dispersion shown in FIG. 7, and “B” corresponds to the dispersion shown in FIG. When both are compared, there is almost no difference in the particle size distribution. In addition, the average particle diameter values of the two are “A” of 0.29 μm and “B” of 0.28 μm, and taking into account measurement errors, there is no difference between the two.
Accordingly, it is understood that the remaining of a minute amount of coarse particles cannot be detected only by the definition of the known average particle size (particle size), and it is not possible to cope with the recent high-resolution negative / positive development. The presence of such a minute amount of coarse particles can be recognized for the first time by observing the coating solution at the microscope level.

Next, a method of removing coarse particles after dispersing the organic charge generating material will be described.
That is, it is a method in which a dispersion liquid with as fine a particle as possible is prepared and then filtered through an appropriate filter. For the preparation of the dispersion, a general method is used. By dispersing the organic charge generating substance in a suitable solvent together with a binder resin as necessary, using a ball mill, attritor, sand mill, bead mill, ultrasonic wave, etc. It is obtained. At this time, the binder resin may be selected depending on the electrostatic characteristics of the photoreceptor, and the solvent may be selected depending on the wettability to the pigment, the dispersibility of the pigment, and the like.
This method is a very effective means in that it can remove a minute amount of coarse particles that cannot be visually observed (or cannot be detected by particle size measurement), and that the particle size distribution is uniform. Specifically, the dispersion prepared as described above is filtered through a filter having an effective pore size of 5 μm or less, more preferably 3 μm or less, thereby completing the dispersion. Also by this method, a dispersion liquid containing only an organic charge generating substance having a small particle size (0.25 μm or less, preferably 0.2 μm or less) can be prepared, and a photoconductor using the dispersion is mounted on an image forming apparatus. By using it, the effect of the present application is made more remarkable.
At this time, when the particle size of the dispersion to be filtered is too large or the particle size distribution is too wide, the loss due to filtration becomes large or the filtration becomes clogged and filtration becomes impossible. There is a case. For this reason, in the dispersion before filtration, it is desirable to carry out dispersion until the average particle size is 0.3 μm or less and the standard deviation reaches 0.2 μm or less. When the average particle size is 0.3 μm or more, the loss due to filtration increases, and when the standard deviation is 0.2 μm or more, there may be a problem that the filtration time becomes very long.

  The charge generation material used in the present invention has an extremely strong intermolecular hydrogen bonding force, which is a feature of the charge generation material exhibiting highly sensitive characteristics. For this reason, the interaction between the dispersed pigment particles is very strong. As a result, there is a great possibility that the charge generation material particles dispersed by a disperser etc. are re-aggregated by dilution or the like. Such agglomerates can be removed. At this time, since the dispersion is in a thixotropic state, particles having a size smaller than the effective pore size of the filter to be used are removed. Or the liquid which shows structural viscosity can also be changed into the state close | similar to Newton property by a filter process. In this way, the effect of the present invention is remarkably improved by removing the coarse particles of the charge generation material.

  The filter for filtering the dispersion varies depending on the size of coarse particles to be removed, but according to the study by the present inventors, as a photoreceptor used in an electrophotographic apparatus that requires a resolution of about 600 dpi. The presence of coarse particles of at least 3 μm affects the image. Therefore, a filter with an effective pore size of 5 μm or less should be used. More preferably, a filter having an effective pore size of 3 μm or less is used. As for the effective pore size, the finer the particle, the more effective the removal of coarse particles. However, if the particle size is too fine, the necessary pigment particles themselves are also filtered, and therefore there is an appropriate size. In addition, if it is too fine, it takes time for filtration, clogging of the filter, and excessive load is applied when liquid is sent using a pump or the like. As a matter of course, a material having resistance to the solvent used in the dispersion to be filtered is used as the material of the filter used here.

The charge transport layer can be formed by dissolving or dispersing the charge transport material and the binder resin in an appropriate solvent, and applying and drying the solution on the charge generation layer. Moreover, a plasticizer, a leveling agent, antioxidant, etc. can also be added as needed.
Charge transport materials include hole transport materials and electron transport materials. Examples of hole transport materials include poly-N-vinylcarbazole and derivatives thereof, poly-γ-carbazolylethyl glutamate and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, Oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazolines Derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, etc., bisstilbene derivatives, enamine derivatives, etc. Other known materials may be mentioned. These charge transport materials may be used alone or in combination of two or more.
Examples of the electron transporting material include chloroanil, bromoanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4 , 5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophen-4-one, 1,3,7-tri Examples thereof include electron-accepting substances such as nitrodibenzothiophene-5,5-dioxide and benzoquinone derivatives.

Binder resins include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, poly Vinylidene chloride, polyarate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-vinyl carbazole, acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenol resin And thermoplastic or thermosetting resins such as alkyd resins.
The amount of the charge transport material is appropriately 20 to 300 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the binder resin. The thickness of the charge transport layer is preferably about 5 to 100 μm.
As the solvent used here, tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone and the like are used. Among them, the use of a non-halogen solvent is desirable for the purpose of reducing the environmental load. Specifically, cyclic ethers such as tetrahydrofuran, dioxolane and dioxane, aromatic hydrocarbons such as toluene and xylene, and derivatives thereof are preferably used.

This is not a problem when the photosensitive layer has a single layer structure or when a charge generation layer is formed on the charge transport layer, but in the case of a photosensitive layer that forms a charge transport layer on the charge generation layer, an appropriate charge transport material is used. If is not selected, there are cases where the static elimination light does not reach the charge generation layer sufficiently and the static elimination action does not work clearly. In addition, there is a case where the charge transport material is easily deteriorated by absorbing the static elimination light, and conversely, a residual potential rise is generated. Therefore, in the case of the above configuration, it is desirable that the transmittance of the charge transport layer with respect to the charge removal light is 30% or more, preferably 50% or more, and more desirably 85% or more.
In order to set the charge transport layer to such a condition, it is important to select a charge transport material appropriate for the static elimination light and form the charge transport layer. Among the charge transport materials described above, a charge transport material having a triarylamine skeleton is suitable as a charge transport material for use in the photoreceptor of the present invention because it easily transmits static elimination light of 480 nm or less and has high mobility. It is.

Among charge transport materials having a triarylamine skeleton, a charge transport material represented by the following formula (III) is particularly effectively used.
(In the formula, Ar ₁ and Ar ₃ represent an aromatic ring group which may have a substituent, Ar ₂ represents an aromatic ring group which may have a substituent. R ₁ has a substituent. also alkyl group, an optionally substituted aralkyl group, .Ar ₁ and R ₁ which represents an aromatic ring group which may have a good vinyl groups and substituents may have a substituent bonded to A ring may be formed.)

In the present invention, a plasticizer or a leveling agent may be added to the charge transport layer. As the plasticizer, those used as general plasticizers such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is suitably about 0 to 30% by weight based on the binder resin. As the leveling agent, silicone oils such as dimethyl silicone oil and methylphenyl silicone oil, polymers or oligomers having a perfluoroalkyl group in the side chain are used, and the amount used is 0 to 0 with respect to the binder resin. 1% by weight is suitable.
In addition, a polymer charge transport material having a function as a charge transport material and a function of a binder resin is also preferably used for the charge transport layer. The charge transport layer composed of these polymer charge transport materials is excellent in wear resistance. As the polymer charge transport material, known materials can be used, and in particular, a polycarbonate containing a triarylamine structure in the main chain and / or side chain is preferably used.

In the electrophotographic photoreceptor of the present invention, a protective layer is provided on the photosensitive layer for the purpose of protecting the photosensitive layer. In recent years, computers have been used on a daily basis, and there has been a demand for miniaturization of devices as well as high-speed output by printers. Therefore, by providing a protective layer and improving the durability, it is possible to use the photosensitive member of the present invention with high sensitivity and no abnormal defects.
An effective protective layer used in the present invention is composed of a diamond-like carbon containing hydrogen and / or an amorphous carbon structure.
The protective layer that can be used in the present invention has a diamond-like carbon containing hydrogen or an amorphous carbon structure. The protective layer preferably has a C—C bond similar to diamond having SP3 orbitals. Note that a film having a structure similar to graphite having SP2 orbits may be used, or an amorphous film may be used. Further, additive elements such as nitrogen, fluorine, boron, phosphorus, chlorine, bromine and iodine may be contained. The volume resistance of the protective layer is preferably 10 ⁹ to 10 ¹² Ω · cm, more preferably 10 ¹⁰ to 10 ¹¹ Ω · cm. The Knoop hardness of the protective layer is desirably 400 kg / mm ² or more, and the light transmittance of the protective layer is desirably 50% or more with respect to the wavelength of light to be exposed. The thickness of the protective layer is preferably 0.5 to 5 μm.

When producing the protective layer, a carrier gas such as H ₂ or Ar is used with hydrocarbon gas (methane, ethane, ethylene, acetylene, etc.) as the main material. Furthermore, any gas can be used for supplying the additive element as long as it can be vaporized under reduced pressure or can be vaporized by heating. For example, NH ₃ , N ₂ or the like is used as a gas for supplying nitrogen, C ₂ F ₆ , CH ₃ F or the like is used as a gas for supplying fluorine, B ₂ H ₆ or the like is used as a gas for supplying boron, phosphorus PH ₃ or the like is used as a gas supplying chlorine, CH ₃ Cl, CH ₂ Cl ₂ , CHCl ₃ , CCl ₄ or the like is used as a gas supplying chlorine, and CH ₃ Br or the like is used as a gas supplying bromine. As the gas for supplying iodine, CH ₃ I or the like can be used. Further, as a gas for supplying a plurality of additive elements, NF ₃ , BCl ₃ , BBr, BF ₃ , PF ₃ , PCl ₃ or the like is used. Using the gas as described above, it is formed by a plasma CVD method, a glow discharge decomposition method, a photo CVD method or the like, a sputtering method using graphite or the like as a target, or the like. Although the film forming method is not particularly limited, as a method for forming a carbon-based film having good characteristics as a protective layer, the film is formed with a sputtering effect while being a plasma CVD method. A method (Japanese Patent Laid-Open No. 58-49609) is known. In the method of forming a protective layer mainly composed of carbon using plasma CVD, it is not necessary to heat the support in particular, and a film can be formed at a low temperature of about 150 ° C. or lower. There is also a merit that there is no problem when the protective layer is formed on the layer.

As described above, when a protective layer is formed on the photosensitive layer, there is a case where the neutralizing light does not sufficiently reach the photosensitive layer unless the appropriate protective layer is selected, and the neutralizing action does not work clearly. In addition, the protective layer absorbs the static elimination light, so that it tends to deteriorate, and conversely, there is a case where a residual potential rise is generated. Therefore, in any of the protective layers described above, the transmittance for the static elimination light is 30% or more, preferably 50% or more, and more desirably 85% or more.
The transmittance of the protective layer is measured by the same method as that for the charge transport layer. That is, the protective layer used for the photoconductor is formed alone, and the spectral absorption spectrum is measured with a commercially available spectrophotometer. It is obtained by obtaining the transmittance at the wavelength of the static elimination light used in the image forming apparatus from the spectrum.
In addition, when a protective layer is provided on the photosensitive layer configured in the order of the charge generation layer and the charge transport layer, and the discharge light is irradiated from the surface side of the photoreceptor, the discharge light passes through the protection layer and the charge transport layer. The charge generation layer is irradiated. Therefore, the transmittance in a form in which the charge transport layer and the protective layer are laminated is important. In this case, in the state where the charge transport layer and the protective layer are laminated, it is desirable that the transmittance with respect to the static elimination light is 30% or more, preferably 50% or more, and more desirably 85% or more.
In such a case, the transmittance can be obtained by measuring the spectral absorption spectrum of the coating film in a state where the charge transport layer and the protective layer are laminated as described above.
As described above, providing a protective layer on the surface of the photoconductor not only enhances the durability (wear resistance) of each photoconductor, but is also used in a tandem type full-color image forming apparatus as described below. In such a case, a new effect that does not exist in the monochrome image forming apparatus is also produced.

In the present invention, in order to improve environmental resistance, in order to prevent a decrease in sensitivity and an increase in residual potential, in particular, in each layer such as a protective layer, a charge transport layer, a charge generation layer, a charge blocking layer, and a moire prevention layer. Antioxidants can be added.
(Phenolic compounds)
2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3,5-di-t-butyl-4 -Hydroxyphenyl) propionate, 2,2'-methylene-bis- (4-methyl-6-tert-butylphenol), 2,2'-methylene-bis- (4-ethyl-6-tert-butylphenol), 4, 4'-thiobis- (3-methyl-6-tert-butylphenol), 4,4'-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3-tris- (2-methyl-4 -Hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis- [methylene- -(3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3,3'-bis (4'-hydroxy-3'-t-butylphenyl) butyric acid] Crycol esters, tocopherols, etc.

(Paraphenylenediamines)
N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-phenylenediamine, N, N'- Di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine and the like.
(Hydroquinones)
2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methylhydroquinone, 2- (2-octadecenyl) ) -5-methylhydroquinone and the like.
(Organic sulfur compounds)
Dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like.
(Organic phosphorus compounds)
Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.

These compounds are known as antioxidants such as rubbers, plastics and fats and oils, and commercially available products can be easily obtained. The addition amount of the antioxidant in the present invention is 0.01 to 10% by weight based on the total weight of the layer to be added.
In the case of a full-color image, various types of images are input, but on the contrary, a fixed image may also be input. For example, the presence of a seal in a Japanese document or the like. Something like indicia is usually located towards the edge of the image area, and the colors used are also limited. In a state in which a random image is always written, image writing, development, and transfer are performed on the photoconductor in the image forming element on average. When many image formations are repeated or only a specific image forming element is used, the durability balance is lost. When a photoconductor having a low surface durability (physical / chemical / mechanical) is used in such a state, this difference becomes prominent and easily causes an image problem. On the other hand, when the photoconductor is made highly durable, the amount of such local change is small, and as a result, it becomes difficult to appear as a defect on the image, so that high durability is achieved and the stability of the output image is improved. This is very effective.

-Electrostatic latent image forming means-
The formation of the electrostatic latent image can be performed, for example, by uniformly charging the surface of the electrostatic latent image carrier and then performing imagewise exposure, and is performed by the electrostatic latent image forming unit. be able to.
The electrostatic latent image forming means includes, for example, at least a charger that uniformly charges the surface of the electrostatic latent image carrier and an exposure device that exposes the surface of the electrostatic latent image carrier imagewise. Prepare.
The charger is not particularly limited and may be appropriately selected depending on the purpose. For example, a known contact charging device including a conductive or semiconductive roll, brush, film, rubber blade, etc. And non-contact chargers using corona discharge such as corotron and scorotron (including proximity-type non-contact chargers having a gap of 100 μm or less between the photoreceptor surface and the charger).
The electric field strength applied to the electrostatic latent image carrier by the charger is preferably 20 to 60 V / μm, and more preferably 30 to 50 V / μm. The higher the electric field strength applied to the photoconductor, the better the dot reproducibility. However, if the electric field strength is too high, problems such as dielectric breakdown of the photoconductor and carrier adhesion during development may occur.
The electric field strength is expressed by the following mathematical formula (1).
<Formula (1)>
Electric field strength (V / μm) = SV / G
In Equation (1), SV represents the absolute value (V) of the surface potential at the unexposed portion of the electrostatic latent image carrier at the development position. G represents the film thickness (μm) of the photosensitive layer including at least the photosensitive layer (charge generation layer and charge transport layer).

The exposure can be performed, for example, by exposing the surface of the latent electrostatic image bearing member imagewise using the exposure device. The type of the exposure device is not particularly limited and may be appropriately selected according to the purpose. For example, various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, and a liquid crystal shutter optical system. Is mentioned. In the present invention, a back light system in which imagewise exposure is performed from the back side of the electrostatic latent image carrier may be employed.
As the light source of the exposure device, a light source capable of ensuring high luminance such as a light emitting diode (LED), a semiconductor laser (LD), or electroluminescence (EL) is used.
Depending on the resolution of the light source (write light) to be used, the resolution of the electrostatic latent image and thus the toner image to be formed is determined, and the higher the resolution, the clearer the image. However, if writing is performed at a higher resolution, writing takes longer, so writing with one writing light source is limited by the drum linear speed (process speed). Therefore, when there is one writing light source, a resolution of about 2400 dpi is the upper limit. If there are a plurality of writing light sources, each of them only has to bear the writing area, and the upper limit is substantially “2400 dpi × number of writing light sources”. Among these light sources, light emitting diodes and semiconductor lasers have high irradiation energy and are used favorably.
Further, since a finer electrostatic latent image is formed by using a light source having a wavelength shorter than 450 nm as the light source wavelength of the exposure device, it is effectively used in the present invention. Examples of a technique for causing laser oscillation in such a wavelength range include a method of halving the wavelength of laser light using second harmonic generation (SHG) and a method using a wide gap semiconductor. In recent years, LDs that oscillate in the wavelength region of 400 to 410 nm have also been developed, and optical systems using these have been developed, and can be beneficially used in the present invention. The lower limit of the wavelength that can be used for the current writing light is about 350 nm, although it varies depending on the materials constituting the charge transport layer and the protective layer. With the development of new materials and lasers, this lower limit will be shortened.

-Development means-
The development can be performed by developing the electrostatic latent image with toner to form a visible image. As the toner, toner having the same polarity as the charged polarity of the photoreceptor is used, and the electrostatic latent image is developed by reversal development (negative / positive development). There are two methods, a one-component method in which development is performed with toner alone and a two-component method in which a two-component developer comprising a toner and a carrier is used. Either method can be used favorably.
-Transfer means-
The transfer means is a means for transferring the visible image onto a recording medium. The transfer means can be transferred onto the intermediate transfer body using a method of directly transferring the visible image from the surface of the photoreceptor to the recording medium and an intermediate transfer body. There is a method in which a visual image is primarily transferred and then the visible image is secondarily transferred onto the recording medium. Either aspect can be used satisfactorily, but the former (direct transfer) method with a small number of transfers is preferred when the adverse effect of the transfer is great when the image quality is improved.
The transfer can be performed, for example, by charging the latent electrostatic image bearing member (photoconductor) of the visible image using a transfer charger, and can be performed by the transfer unit. The transfer unit is not particularly limited, and can be appropriately selected from known transfer units according to the purpose. For example, a transfer conveyance belt that can simultaneously convey a recording medium can be preferably cited. It is done.
The transfer means (the primary transfer means, the secondary transfer means) is a transfer for peeling and charging the visible image formed on the electrostatic latent image carrier (photoconductor) to the recording medium side. It is preferable to have at least a charger. There may be one transfer means or two or more transfer means. Examples of the transfer charger include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device. The recording medium is not particularly limited and can be appropriately selected from known recording media (recording paper).
The transfer charger may be a transfer belt or a transfer roller, but it is desirable to use a contact type such as a transfer belt or transfer roller that generates less ozone. As a voltage / current application method at the time of transfer, either a constant voltage method or a constant current method can be used. However, the transfer charge amount can be kept constant, and the constant voltage method has excellent stability. The current method is more desirable. As such a transfer member, a known member can be used as long as the structure of the present invention can be satisfied.

As described above, the amount of charge passing through the photosensitive member per one cycle of image formation varies greatly depending on the surface potential of the photosensitive member after transfer (surface potential when entering the charge eliminating portion). The larger this is, the greater the influence on the electrostatic fatigue of the photoreceptor in repeated use.
This passing charge amount corresponds to the amount of charge flowing in the film thickness direction of the photoreceptor. As an operation in the image forming apparatus of the photoconductor, the main charger is charged to a desired charging potential (in most cases, negatively charged), and optical writing is performed based on an input signal corresponding to the original. At this time, photocarriers are generated in the portion where writing is performed, and the surface charge is neutralized (potential decay). At this time, the amount of charge depending on the amount of generated photocarriers flows in the direction of the photoreceptor film thickness. On the other hand, the region where the optical writing is not performed (non-writing portion) proceeds to the static elimination process through the development process and the transfer process (a cleaning process is performed before that if necessary). Here, when the surface potential of the photoconductor is close to the potential applied by main charging (excluding dark decay), the amount of charge is almost the same as that in the area where optical writing is performed. Will flow into. In general, since the current document has a low writing rate, this method means that the current passing through the photoconductor in repeated use is mostly current flowing in the static elimination process (the writing rate is 10%). Then, the current flowing in the static elimination process occupies 90% of the total).
This passing charge greatly affects the electrostatic characteristics of the photoconductor, for example, causing deterioration of the material constituting the photoconductor. As a result, depending on the passing charge amount, the residual potential of the photoreceptor is raised. When the residual potential of the photoconductor is increased, the image density is lowered in the negative and positive development used in the present invention, which is a serious problem. Therefore, there is a problem of how to reduce the passing charge amount of the photosensitive member in order to extend the life (high durability) of the photosensitive member in the image forming apparatus.

On the other hand, there is a way of thinking that the photostatic discharge is not performed, but if the main charger is not sufficiently charged, the charging cannot be stabilized and a problem such as an afterimage may occur. The passing charge of the photoconductor is generated by the movement of the generated optical carrier by light irradiation by the electric potential (the electric field generated thereby) charged on the surface of the photoconductor. Accordingly, if the surface potential of the photosensitive member can be attenuated by means other than light, the amount of passing charge per one rotation of the photosensitive member (one cycle of image formation) can be reduced.
For this purpose, it is effective to adjust the charge passing through the photosensitive member by adjusting the transfer bias in the transfer process. That is, a non-writing portion that is charged by main charging and does not perform writing enters the transfer process in a state close to the charged potential except for the dark attenuation amount. At this time, the absolute value on the polarity side charged by the main charger is reduced to 100 V or less, so that almost no photocarrier is generated even if the subsequent charge removal process is entered, and no passing charge is generated. This value is preferably closer to 0V.
Furthermore, by adjusting the transfer bias, by applying a transfer bias so that the surface potential of the photosensitive member is charged to a polarity opposite to the charging polarity applied by the main charging, it is more preferable because no optical carrier is generated. . However, under transfer conditions that charge to a reverse polarity, there may be cases where a large amount of transfer dust occurs or the main charge of the next image forming process (cycle) cannot catch up. In that case, since a problem such as an afterimage may occur, the absolute value of the reverse polarity is preferably 100 V or less.
Adding the control as described above can effectively use the effect of the present invention as a remarkable effect.

-Fixing means-
The fixing may be performed each time the visible image transferred to the recording medium is fixed by using a fixing device and transferred to the recording medium for each color toner, or the toner is stacked on each color toner. May be performed simultaneously at the same time.
There is no restriction | limiting in particular as said fixing device, Although it can select suitably according to the objective, A well-known heating-pressing means is suitable. Examples of the heating and pressing means include a combination of a heating roller and a pressure roller, a combination of a heating roller, a pressure roller, and an endless belt. The heating in the heating and pressing means is usually preferably 80 ° C to 200 ° C. In the present invention, for example, a known optical fixing device may be used together with or in place of the fixing step and the fixing unit depending on the purpose.

-Static elimination means-
The neutralization means may be any wavelength as long as it has a wavelength of less than 500 nm (preferably less than 480 nm, more preferably less than 450 nm) and can neutralize the electrostatic latent image carrier. For example, a semiconductor laser (LD), electroluminescence (EL), and the like are preferable.
For light sources such as semiconductor lasers (LD) and electroluminescence (EL), semiconductor lasers (LD) and electroluminescence (EL) having an oscillation wavelength of less than 500 nm, or fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium A combination of a lamp, a xenon lamp, or the like with an appropriate optical filter that can limit light emission to less than 500 nm can be used. The optical filter includes various types such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter in order to irradiate only light in a desired wavelength range (less than 500 nm). A filter can also be used.

There are several techniques for causing laser oscillation in such a wavelength range. One is to use a non-linear optical material and to halve the wavelength of the laser beam using second harmonic generation (SHG) (for example, Japanese Patent Laid-Open Nos. 9-275242 and 9). No. 189930, JP-A-5-313033, etc.). Since this system can use a GaAs-based LD or YAG laser that has already established technology and can output high power as a primary light source, it is possible to extend the life and output. The other uses a wide-gap semiconductor, and the size of the apparatus can be reduced as compared with a device using SHG. LD using a ZnSe-based semiconductor (see JP-A-7-321409, JP-A-6-334272, etc.) or a GaN-based semiconductor (see JP-A-8-88441, JP-A-7-335975, etc.) However, because of its high luminous efficiency, it has been the subject of many studies. Also, as a relatively recent technology, Nichia Chemical Industries has put into practical use LD (405 nm oscillation) using a GaN-based semiconductor, and has developed a writing system far more advanced than the above-mentioned technology. It can be used beneficially.
In addition, LED lamps using the above materials are on the market, and these can also be used effectively.

On the other hand, at the present time, the lower limit is determined by the following problem. That is, as a material constituting the photoconductor (the charge transport layer or the protective layer existing on the writing light incident side), a charge transport material can be mentioned. Among charge transport materials having high mobility and usable at a practical level. In other words, there is no material that is sufficiently transparent with respect to light having a component shorter than about 350 nm. This is because most of the charge transport materials currently developed have a triarylamine structure, and the absorption edge on the long wavelength side of this material is approximately 300 to 350 nm. Therefore, if further shortening of the wavelength of the static elimination light source and further transparency of the charge transport material (shortening of absorption wavelength) are realized, the oscillation wavelength of the light source that can be used in the present invention is further reduced. Will extend.
-Others-
The cleaning means is not particularly limited as long as it can remove the electrophotographic toner remaining on the electrostatic latent image carrier, and can be appropriately selected from known cleaners. Suitable examples include brush cleaners, electrostatic brush cleaners, magnetic roller cleaners, blade cleaners, brush cleaners, web cleaners, and the like.

The recycling unit is a step of recycling the electrophotographic color toner removed by the cleaning unit to the developing unit, and examples thereof include a known conveyance unit.
The control means is a process for controlling the respective steps, and can be suitably performed by the control means. The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.

Here, an aspect of the image forming apparatus of the present invention will be described with reference to FIG.
FIG. 10 is a schematic diagram for explaining the image forming apparatus of the present invention, and modifications as described later also belong to the category of the present invention.
In FIG. 10, a photosensitive member (1) as an electrostatic latent image carrier is a laminated photosensitive member comprising a charge generating layer containing at least an organic charge generating material and a charge transporting layer containing a charge transporting material on a support. And a protective layer having a diamond-like carbon containing hydrogen and / or an amorphous carbon structure. The photosensitive member (1) has a drum shape, but may be a sheet or an endless belt.
As the charging member (3), a wire-type charger or a roller-shaped charger is used. When high speed charging is required, a scorotron type charger is used favorably. In a compact or tandem type image forming apparatus using a plurality of photoconductors described later, acid gas (NOx, SOx, etc.) A roller-shaped charger that generates less ozone is effectively used. Although the photosensitive member is charged by this charger, the higher the electric field strength applied to the photosensitive member, the better the dot reproducibility. Therefore, it is desirable to apply an electric field strength of 20 V / μm or more. . However, there is a possibility that problems such as dielectric breakdown of the photosensitive member and carrier adhesion during development occur, and the upper limit is approximately 60 V / μm or less, more preferably 50 V / μm or less.

In addition, the image exposure unit (5) can ensure high brightness such as a light emitting diode (LED), a semiconductor laser (LD), and electroluminescence (EL), and can be written at a high resolution (600 dpi or more). Is used. Depending on the resolution of the light source (writing light), the resolution of the formed electrostatic latent image, and thus the toner image, is determined. The higher the resolution, the clearer the image. However, if writing is performed at a higher resolution, writing takes longer, so writing with one writing light source is limited by the drum linear speed (process speed). Therefore, when there is one writing light source, a resolution of about 1200 dpi is the upper limit. When there are a plurality of write light sources, each of them only has to bear a write area, and the upper limit is substantially “1200 dpi × number of write light sources”. Among these light sources, light emitting diodes and semiconductor lasers have high irradiation energy and are used favorably.
Further, as described above, it is an effective means to use laser light having an oscillation wavelength shorter than 450 nm.

The developing unit (6) which is a developing means has at least one developing sleeve.
In the developing unit (6), toner having the same polarity as the charged polarity of the photoreceptor is used, and the electrostatic latent image is developed by reversal development (negative / positive development). Depending on the light source used in the previous image exposure unit (5), in the case of a digital light source used in recent years, inversion that performs toner development on the writing portion generally corresponding to a low image area ratio The development method is advantageous in consideration of the life of the light source. There are two methods, a one-component method in which development is performed with toner alone and a two-component method in which a two-component developer comprising a toner and a carrier is used. Either method can be used favorably.

The transfer charger (10) may be a transfer belt or a transfer roller, but it is desirable to use a contact type such as a transfer belt or transfer roller that generates less ozone. As a voltage / current application method at the time of transfer, either a constant voltage method or a constant current method can be used. However, the transfer charge amount can be kept constant, and the constant voltage method has excellent stability. The current method is more desirable. In particular, by subtracting the current that flows from the power supply member (high-voltage power supply) that supplies electric charge to the transfer member and does not flow into the photosensitive member, the current to the photosensitive member is subtracted. A method of controlling the value is preferred.
The transfer current is a current based on the amount of charge required to peel off the toner electrostatically attached to the photosensitive member and transfer it to a transfer target (transfer paper or intermediate transfer member). In order to avoid transfer defects such as transfer residue, it is only necessary to increase the transfer current. However, in the case of using negative and positive development, charging with a polarity opposite to the charging polarity of the photosensitive member is given. As a result, the electrostatic fatigue of the photoconductor becomes remarkable. The larger the transfer current, the more advantageous it is because a charge amount exceeding the electrostatic adhesion force between the photoconductor and the toner can be given, but if a certain threshold value is exceeded, a discharge phenomenon occurs between the transfer member and the photoconductor, resulting in a fine As a result, the developed toner image is scattered. For this reason, the upper limit is a range in which this discharge phenomenon does not occur. This threshold varies depending on the gap (distance) between the transfer member and the photoconductor, the material constituting the both, and the like, but the discharge phenomenon can be avoided by using it at about 200 μA or less. Therefore, the upper limit value of the transfer current is about 200 μA.
Further, the toner image formed on the photoconductor is transferred onto the transfer paper to become an image on the transfer paper. At this time, there are two methods. One is a method of directly transferring a toner image developed on the surface of a photoreceptor as shown in FIG. 10 to the transfer paper, and the other is that the toner image is once transferred from the photoreceptor to an intermediate transfer body, and this is transferred to the transfer paper. It is the method of transferring to. Either case can be used in the present invention.
As such a transfer member, a known member can be used as long as the structure of the present invention can be satisfied.
Further, by controlling the transfer current as described above, reducing the photoreceptor surface potential after transfer (the unexposed portion of the writing light) reduces the amount of charge passing through the photoreceptor per one cycle of image formation. Can be used effectively in the present invention.

The light source such as the static elimination lamp (2) has a wavelength of less than 500 nm (preferably less than 480 nm, more preferably less than 450 nm), and it is only necessary to perform static elimination on the electrostatic latent image carrier. The static eliminator can be appropriately selected, and for example, a semiconductor laser (LD), electroluminescence (EL), and the like are preferable.
For light sources such as semiconductor lasers (LD) and electroluminescence (EL), semiconductor lasers (LD) and electroluminescence (EL) having an oscillation wavelength of less than 500 nm, or fluorescent lamps, tungsten lamps, halogen lamps, mercury lamps, sodium A combination of a lamp, a xenon lamp, or the like with an appropriate optical filter that can limit light emission to less than 500 nm can be used. The optical filter includes various types such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter in order to irradiate only light in a desired wavelength range (less than 500 nm). A filter can also be used.
The lower limit of the wavelength used varies depending on the transmittance of the charge transport layer and the protective layer used in the photoreceptor, but the lower limit is about 300 to 350 nm.

In FIG. 10, (8) is a registration roller, (11) is a separation charger, and (12) is a separation claw.
In addition, the toner developed on the photoreceptor (1) by the developing unit (6) is transferred to the transfer paper (9), but when toner remaining on the photoreceptor (1) is generated, a fur brush ( 14) and the blade (15). Cleaning may be performed only with a cleaning brush, and a known brush such as a fur brush or a mag fur brush is used as the cleaning brush.
Next, FIG. 11 is a schematic diagram for explaining the tandem type full-color image forming apparatus of the present invention, and the following modifications also belong to the category of the present invention.
In FIG. 11, reference numerals (16Y), (16M), (16C), and (16K) denote drum-shaped photoconductors, and the photoconductors include a charge generation layer containing at least an organic charge generation material on a support, A laminated photosensitive layer comprising a charge transport layer containing a charge transport material and a protective layer having a diamond-like carbon and / or amorphous carbon structure containing hydrogen are provided.

  The photoconductors (16Y), (16M), (16C), and (16K) can rotate in the direction of the arrow in FIG. 11, and the chargers (17Y), (17M), and (17C) at least in the order of rotation therearound. , (17K), developing means (19Y) having at least one developing sleeve (19M), (19C), (19K), cleaning member (20Y), (20M), (20C), (20K), from 500 nm Discharge means (27Y), (27M), (27C), and (27K) for irradiating light with a short wavelength (preferably less than 480 nm, more preferably less than 450 nm) are arranged. The chargers (17Y), (17M), (17C), and (17K) are chargers that constitute a charging device for uniformly charging the surface of the photoreceptor. From the surface of the photoreceptor between the chargers (17Y), (17M), (17C), (17K) and the developing means (19Y), (19M), (19C), (19K), an exposure unit (18Y) , (18M), (18C), and (18K) are irradiated with laser light, and electrostatic latent images are formed on the photoreceptors (16Y), (16M), (16C), and (16K). Yes. Then, the four image forming elements (25Y), (25M), (25C), and (25K) centering on such photoconductors (16Y), (16M), (16C), and (16K) serve as transfer materials. They are juxtaposed along the transfer conveyance belt (22) which is a conveyance means. The transfer / conveying belt (22) includes developing means (19Y), (19M), (19C), (19K) and a cleaning member (20Y) of the image forming units (25Y), (25M), (25C), (25K). , (20M), (20C), and (20K) are in contact with the photosensitive member (16Y), (16M), (16C), and (16K), and contact the back side of the photosensitive member side of the transfer conveyance belt (22). Transfer brushes (21Y), (21M), (21C), and (21K) for applying a transfer bias are arranged on the surface (back surface). Each of the image forming elements (25Y), (25M), (25C), and (25K) is different in the color of the toner inside the developing device, and the others are the same in configuration.

In the full-color image forming apparatus having the configuration shown in FIG. 11, the image forming operation is performed as follows. First, in each of the image forming elements (25Y), (25M), (25C), and (25K), an electrostatic latent image is formed on the photoconductors (16Y), (16M), (16C), and (16K). It has become. Then, such photoconductors (16Y), (16M), (16C), and (16K) rotate, and the photoconductors are charged by the chargers (17Y), (17M), (17C), and (17K). The At this time, in order to form a high-definition latent image, charging is performed so that the electric field strength of the photosensitive member is 20 V / μm or more (60 V / μm or less, preferably 50 V / μm or less).
Next, writing is performed at a resolution of 1200 dpi or more (preferably 2400 dpi or more) with a laser beam at the exposed portions (18Y), (18M), (18C), and (18K) arranged outside the photoreceptor, and created. An electrostatic latent image corresponding to each color image is formed. As the writing light source, as described above, a light source suitable for an arbitrary photoconductor is used. In this case as well, 2400 dpi writing is generally the upper limit for one writing light source. Also in this case, it is an effective means to use laser light having an oscillation wavelength shorter than 450 nm as described above.

Next, the latent image is developed by the developing means (19Y), (19M), (19C), and (19K) to form a toner image. Developing means (19Y), (19M), (19C), and (19K) are developing means for developing with toners of Y (yellow), M (magenta), C (cyan), and K (black), respectively. The toner images of the respective colors formed on the two photoconductors (16Y), (16M), (16C), and (16K) are superimposed on the transfer paper. The transfer paper (26) is fed out from the tray by a paper feeding roller (not shown), temporarily stopped by a pair of registration rollers (23), and transferred and conveyed (22) in synchronization with the image formation on the photosensitive member. ). The transfer paper (26) held on the transfer conveyance belt (22) is conveyed, and each color is in contact with each photoconductor (16Y), (16M), (16C), (16K) (transfer section). The toner image is transferred.
The toner image on the photoconductor includes transfer bias applied to the transfer brushes (21Y), (21M), (21C), and (21K) and the photoconductors (16Y), (16M), (16C), and (16K). The image is transferred onto the transfer paper (26) by an electric field formed from the potential difference. Then, the recording paper (26) on which the four color toner images are passed through the four transfer sections is conveyed to the fixing device (24), where the toner is fixed, and is discharged to a paper discharge section (not shown).
Further, residual toner remaining on each of the photoconductors (16Y), (16M), (16C), and (16K) without being transferred by the transfer unit is removed from the cleaning devices (20Y), (20M), (20C), ( 20K).

Subsequently, excess residual charges on the photosensitive member are removed by the charge removal members (27Y), (27M), (27C), and (27K) having a light source having a wavelength shorter than 500 nm. Thereafter, charging is performed uniformly by the charger, and the next image formation is performed.
In the example of FIG. 11, the image forming elements are arranged in the order of Y (yellow), M (magenta), C (cyan), and K (black) from the upstream side to the downstream side in the transfer paper conveyance direction. However, it is not limited to this order, and the color order is arbitrarily set. Further, when a black-only document is created, it is particularly effective to use the present invention to provide a mechanism that stops image forming elements other than black [(25Y), (25M), (25C)]. .
Further, as described above, the surface of the photoreceptor after transfer is preferably charged to 100 V or less on the polarity side charged by the main charger, more preferably charged to the reverse polarity side, and to the reverse polarity side. It is particularly preferable to charge to 100 V or less. As a result, an increase in residual potential due to repeated use of the photoreceptor can be reduced.

The image forming means as described above may be fixedly incorporated in a copying apparatus, a facsimile, or a printer, but may be incorporated in these apparatuses in the form of a process cartridge. The process cartridge is a single device (part) that contains a photosensitive member, and further includes an electrostatic latent image forming unit, a developing unit, a transfer unit, a cleaning unit, a charge eliminating unit, and the like. There are many shapes and the like of the process cartridge, but a general example is the one shown in FIG. The photoconductor (201) comprises a charge generating layer containing at least an organic charge generating material on a support, a laminated photosensitive layer comprising a charge transporting layer containing a charge transporting material, diamond-like carbon containing hydrogen, and / or Alternatively, a protective layer having an amorphous carbon structure is provided.
As described above, a light source capable of writing with a resolution of 600 dpi or higher is preferably used for the image exposure unit (203), and an arbitrary charger is used for the charger (202). In FIG. 12, (204) is a developing means having at least one developing sleeve, (205) is a transfer body, (206) is a transfer means, (207) is a cleaning means, and (208) is a wavelength shorter than 500 nm. A static elimination member having a light source (preferably less than 480 nm, more preferably less than 450 nm).

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to the following Example at all. All parts are parts by mass.
First, a method for synthesizing the azo pigment and titanyl phthalocyanine crystal used in the present invention will be described. The azo pigments used in the following examples were prepared according to the methods described in Japanese Patent Publication No. 60-29109 and Japanese Patent No. 3026645. Moreover, the titanyl phthalocyanine crystal | crystallization was produced according to Unexamined-Japanese-Patent No. 2001-19871 and Unexamined-Japanese-Patent No. 2004-83859.
-Synthesis of titanyl phthalocyanine crystals-
(Synthesis Example 1)
A pigment was prepared according to Japanese Patent Application Laid-Open No. 2001-19871, Synthesis Example 1. That is, 29.2 g of 1,3-diiminoisoindoline and 200 ml of sulfolane are mixed, and 20.4 g of titanium tetrabutoxide is added dropwise under a nitrogen stream. After completion of the dropwise addition, the temperature was gradually raised to 180 ° C., and the reaction was carried out by stirring for 5 hours while maintaining the reaction temperature between 170 ° C. and 180 ° C. After the reaction is complete, the mixture is allowed to cool, and then the precipitate is filtered, washed with chloroform until the powder turns blue, then washed several times with methanol, then washed several times with hot water at 80 ° C. and dried. Crude titanyl phthalocyanine was obtained. Crude titanyl phthalocyanine is dissolved in 20 times the amount of concentrated sulfuric acid, added dropwise to 100 times the amount of ice water with stirring, the precipitated crystals are filtered, and then ion-exchanged water (pH: 7.) until the washing solution becomes neutral. 0, specific conductivity: 1.0 μS / cm) Repeated washing with water (pH value of ion-exchanged water after washing was 6.8, specific conductivity was 2.6 μS / cm), wet of titanyl phthalocyanine pigment A cake (water paste) was obtained. 40 g of the obtained wet cake (water paste) was put into 200 g of tetrahydrofuran, stirred for 4 hours, filtered and dried to obtain titanyl phthalocyanine powder. This is designated as Pigment 1.
The solid content concentration of the wet cake was 15% by mass. The crystal conversion solvent was used in a mass ratio of 33 times that of the wet cake. In addition, the halogen-containing compound is not used for the raw material of the synthesis example 1.
The obtained titanyl phthalocyanine powder was subjected to X-ray diffraction spectrum measurement under the following conditions. As a result, the Bragg angle 2θ with respect to Cu-Kα ray (wavelength 1.542Å) was 27.2 ± 0.2 °, and the maximum peak and minimum angle 7 Has a peak at .3 ± 0.2 °, and further has major peaks at 9.4 ± 0.2 °, 9.6 ± 0.2 °, 24.0 ± 0.2 °, and 7 A titanyl phthalocyanine powder having no peak between the peak at 3 ° and the peak at 9.4 ° and further having no peak at 26.3 ° was obtained. The result is shown in FIG.

A part of the water paste obtained in Synthesis Example 1 was dried at 80 ° C. under reduced pressure (5 mmHg) for 2 days to obtain a low crystalline titanyl phthalocyanine powder. The X-ray diffraction spectrum of the dry powder of water paste is shown in FIG.
<X-ray diffraction spectrum measurement conditions>
X-ray tube: Cu
Voltage: 50kV
Current: 30mA
Scanning speed: 2 ° / min Scanning range: 3 ° -40 °
Time constant: 2 seconds

(Synthesis Example 2)
-Synthesis of titanyl phthalocyanine crystals-
According to the method of JP 2004-83859 A, Example 1, an aqueous paste of titanyl phthalocyanine pigment was synthesized, and crystal conversion was performed as follows to obtain a phthalocyanine crystal having smaller primary particles than the previous synthesis example 1. .
400 parts by mass of tetrahydrofuran was added to 60 parts by mass of the aqueous paste before crystal conversion obtained in Synthesis Example 1 above, and the mixture was vigorously stirred (2000 rpm) with a homomixer (Kennis, MARKIIf model) at room temperature. When the color changed to light blue (20 minutes after the start of stirring), stirring was stopped and filtration under reduced pressure was immediately performed. The crystals obtained on the filtration device were washed with tetrahydrofuran to obtain a wet cake of pigment. This was dried under reduced pressure (5 mmHg) at 70 ° C. for 2 days to obtain 8.5 parts by mass of titanyl phthalocyanine crystals. This is designated as Pigment 2. The raw material of Synthesis Example 2 does not use a halogen-containing compound. The solid content concentration of the wet cake was 15% by mass. The crystal conversion solvent was used in a mass ratio of 44 times that of the wet cake.

Part of the pre-crystallized titanyl phthalocyanine (water paste) prepared in Synthesis Example 1 was diluted with ion-exchanged water to approximately 1% by mass, and the surface was scooped with a copper net that was subjected to conductive treatment, and titanyl phthalocyanine was obtained. Were observed with a transmission electron microscope (TEM, Hitachi: H-9000NAR) at a magnification of 75000 times. The average particle size was determined as follows.
The TEM image observed as described above is taken as a TEM photograph, and 30 titanyl phthalocyanine particles (a shape close to a needle shape) projected are arbitrarily selected, and the size of each major axis is measured. An arithmetic average of the major diameters of the measured 30 individuals was determined and used as the average particle diameter. The average particle diameter in the water paste (wet cake) in Synthesis Example 1 determined by the above method was 0.06 μm.
In addition, the titanyl phthalocyanine crystal after crystal conversion just before filtration in Synthesis Example 1 and Synthesis Example 2 was diluted with tetrahydrofuran so as to be about 1% by mass, and observed in the same manner as the above method. The average particle diameter determined as described above is shown in Table 1. In addition, the titanyl phthalocyanine crystal produced in Synthesis Example 1 and Synthesis Example 2 did not necessarily have the same shape of all crystals (a shape close to a triangle, a shape close to a square, etc.). For this reason, the calculation was carried out with the length of the largest diagonal line of the crystal as the major axis.

The pigment 2 produced in Synthesis Example 2 was measured for the X-ray diffraction spectrum by the same method as described above. As a result, the X-ray diffraction spectrum of Pigment 2 prepared in Synthesis Example 2 matched the spectrum of Pigment 1 prepared in Synthesis Example 1.

(Dispersion Preparation Example 1)
Pigment 1 prepared in Synthesis Example 1 was dispersed under the following composition under the following conditions to prepare a dispersion as a charge generation layer coating solution.
Titanyl phthalocyanine pigment (Pigment 1) 15 parts Polyvinyl butyral (manufactured by Sekisui Chemical: BX-1) 10 parts 2-butanone 280 parts All butanone and pigment were added and dispersed for 30 minutes at a rotor rotational speed of 1200 rpm to prepare a dispersion. This was designated as Dispersion Liquid 1.

(Dispersion preparation example 2)
A dispersion was prepared under the same conditions as in Dispersion Preparation Example 1, using Pigment 2 prepared in Synthesis Example 2 instead of Pigment 1 used in Dispersion Preparation Example 1. This was designated as Dispersion Liquid 2.
(Dispersion preparation example 3)
The dispersion 1 prepared in Dispersion Preparation Example 1 was filtered using a cotton wind cartridge filter, TCW-1-CS (effective pore size 1 μm) manufactured by Advantech. During filtration, a pump was used and filtration was performed in a pressurized state. This was designated as Dispersion Liquid 3.
(Dispersion preparation example 4)
Dispersion was performed by pressure filtration in the same manner as in Dispersion Preparation Example 3, except that the filter used in Dispersion Preparation Example 3 was changed to Advantech's Cotton Wind Cartridge Filter and TCW-3-CS (effective pore size 3 μm). A liquid was prepared. This was designated as Dispersion Liquid 4.

(Dispersion preparation example 5)
Dispersion was carried out under the conditions shown below with a formulation having the following composition to prepare a dispersion as a charge generation layer coating solution.
5 parts of azo pigment with the following structure
Polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd .: BX-1) 2 parts Cyclohexanone 250 parts 2-butanone 100 parts Using a PSZ ball having a diameter of 10 mm in a ball mill disperser, all of the solvent in which polyvinyl butyral is dissolved and an azo pigment are added, and the rotational speed is 85 r. . p. m. For 7 days to prepare a dispersion (referred to as dispersion 5).

(Dispersion Preparation Example 6)
A dispersion was prepared in the same manner as Dispersion Preparation Example 5 except that the azo pigment used in Dispersion Preparation Example 5 was changed to one having the following structure (referred to as Dispersion 6).
The particle size distribution of the pigment particles in the dispersion prepared as described above was measured by HORIBA, Ltd .: CAPA-700. The results are shown in Table 2.

(Photoreceptor Preparation Example 1)
On an aluminum drum (JIS 1050) with a diameter of 30 mm, an intermediate layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following composition were sequentially applied and dried to obtain a 3.5 μm intermediate layer, 0. A 5 μm charge generation layer and a 22 μm charge transport layer were formed. Further, a protective layer having a thickness of 3 μm was formed under the following conditions to produce a laminated photoreceptor (referred to as electrophotographic photoreceptor 1).

◎ Intermediate layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 112 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Manufactured by Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 260 parts ◎ charge generation layer coating liquid Dispersion 1 prepared above was used.

◎ Charge transport layer coating solution Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts Charge transport material of the following structural formula 7 parts

◎ Protective layer coating solution The conductive support on which the intermediate layer, the charge generation layer, and the charge transport layer were formed was set in a plasma CVD apparatus as shown in FIGS. 15 to 17 to form a protective layer. In FIG. 15, reference numeral (107) denotes a vacuum chamber of the plasma CVD apparatus, which is partitioned from a load / unload spare chamber (117) by a gate valve (109). The inside of the vacuum chamber (107) is evacuated by an exhaust system (120) [consisting of a pressure regulating valve (121), a turbo molecular pump (122), and a rotary pump (123)], and is kept at a constant pressure. ing. A reaction tank (150) is provided in the vacuum tank (107). Here, the vacuum chamber (107) has shown the state of an AA 'arrow cross section of FIG. The reaction tank has a frame-like structure (102) as shown in FIGS. 16 and 17 (having a square or hexagonal shape when viewed from the electrode side) and a hood (108 that covers the openings at both ends). ), (118), and a pair of first and second electrodes (103), (113) having a same shape disposed on the hood (108), (118) (using a metal mesh such as aluminum) Are). (130) indicates a gas line to be introduced into the reaction tank (150), to which various material gas containers are connected, and each of them passes through a flow meter (129) and from a nozzle (125) into the reaction tank (150). To be introduced.
In the frame-like structure (102), supports [111 (111-1, 111-2... 111-n)] on which the photosensitive layer is formed are arranged as shown in FIGS. Each of the supports is disposed as a third electrode as will be described later. A pair of power supplies [115 (115-1, 115-2)] for applying a first alternating voltage is prepared for each of the electrodes (103), (113). The frequency of the first alternating voltage is 1 to 100 MHz. These power sources are connected to matching transformers (116-1) and (116-2), respectively. The phase in the matching transformer is adjusted by the phase adjuster (126) and can be supplied with a shift of 180 ° or 0 ° from each other. That is, it has a symmetrical or in-phase output. One end (104) and the other end (114) of the matching transformer are connected to the first and second electrodes (103) and (113), respectively. Further, the output-side midpoint (105) of the transformer is held at the ground level. Further, the transformer output-side midpoint (105) and the third electrode, that is, the support [101 (101-1, 101-2... 101-n + 1)] or the frame-like structure 102 electrically connected to them. A power source (119) for applying a second alternating voltage is disposed therebetween. The frequency of the second alternating voltage is 1 to 500 KHz. The output of the first alternating voltage applied to the first and second electrodes is 0.1 to 1 kW at a frequency of 13.56 MHz, and the second alternating voltage applied to the third electrode, that is, the support. Is about 100 W for a frequency of 150 KHz.

A protective layer was formed under the following conditions.
CH ₄ flow rate: 200 sccm
H ₂ flow rate: 100 sccm
Reaction pressure: 0.05 torr
First alternating voltage output: 100 W 13.56 MHz
Bias voltage (DC component): -200V

Example 1
The electrophotographic photosensitive member 1 produced as described above is mounted on an image forming apparatus as shown in FIG. 10, and an image exposure light source is a 780 nm semiconductor laser (image writing by a polygon mirror), a scorotron charger as a charging member, a transfer member A transfer belt was used as a member, and a 428 nm LED (Rohm: half-value width: 65 nm) was used as a static elimination light source. Process conditions before the test are set as follows, and a chart with a writing rate of 6% (characters equivalent to 6% as an image area are written on the entire A4 surface) is continuously 50,000. Sheet printing was performed.
Photoconductor charging potential (unexposed portion potential): −900 V
Development bias: -650V (negative / positive development)
Surface potential after neutralization (unexposed area of writing light): −100V
Evaluation was made by measuring the potential of the photosensitive member exposed area before and after printing 50,000 images.
As a measurement method, a surface potential meter is mounted at the position of the developing portion shown in FIG. The partial potential was measured. The results are shown in Table 3.

(Example 2)
Evaluation was performed in the same manner as in Example 1 except that the light source in Example 1 was changed to a 472 nm LED (manufactured by Seiwa Denki: full width at half maximum of 15 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 1. The results are shown in Table 3.
(Comparative Example 1)
Evaluation was performed in the same manner as in Example 1 except that the neutralization light source in Example 1 was changed to 502 nm LED (manufactured by Seiwa Denki: full width at half maximum of 15 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 1. The results are shown in Table 3.
(Comparative Example 2)
Evaluation was performed in the same manner as in Example 1 except that the static elimination light source in Example 1 was changed to 591 nm LED (Rohm: full width at half maximum: 15 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 1. The results are shown in Table 3.
(Comparative Example 3)
Evaluation was performed in the same manner as in Example 1 except that the static elimination light source in Example 1 was changed to 630 nm LED (Rohm: half width 20 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 1. The results are shown in Table 3.

(Comparative Example 4)
Evaluation was performed in the same manner as in Example 1 except that the static elimination light source in Example 1 was changed to a fluorescent lamp (having the emission spectrum shown in FIG. 1). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 1. The results are shown in Table 3.
(Comparative Example 5)
Except for changing to irradiate substantially the same amount of light at the same time using two 428 nm LEDs (Rohm: half width 65 nm) and 630 nm LEDs (Rohm: half width 20 nm) as the static elimination light source in Example 1 Evaluation was performed in the same manner as in 1. The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 1. The results are shown in Table 3.

From Table 3, when the wavelength of the static elimination light is less than 500 nm (Examples 1 and 2), the exposure after repeated use is compared with the case where a longer wavelength is used (Comparative Examples 1 to 3). It can be seen that the increase in the partial potential is small. In particular, when the thickness is less than 450 nm (Example 1), it can be seen that the effect is more remarkable than (Example 2).
In addition, in the case where the emission distribution is wide and a component of long wavelength light of 500 nm or more is included (Comparative Example 4), a clear effect as in the example is not obtained. In addition, when two types of light sources having different exposure wavelengths are used (Comparative Example 5), it can be seen that the effect of charge removal by the short wavelength light source is reduced.

(Photoreceptor preparation example 2)
In Photoconductor Preparation Example 1, a photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that Dispersion 2 prepared above was used as the charge generation layer coating solution (referred to as electrophotographic photoconductor 2). .
(Example 3)
In Example 1, evaluation was performed in the same manner as in Example 1 except that the electrophotographic photosensitive member 2 was used instead of the electrophotographic photosensitive member 1 used. The results are shown in Table 4.
Example 4
In Example 2, evaluation was performed in the same manner as in Example 2 except that the electrophotographic photosensitive member 2 was used instead of the electrophotographic photosensitive member 1 used. The results are shown in Table 4.
(Comparative Example 6)
In Comparative Example 1, evaluation was performed in the same manner as Comparative Example 1 except that the electrophotographic photosensitive member 2 was used instead of the electrophotographic photosensitive member 1 used. The results are shown in Table 4.
(Comparative Example 7)
In Comparative Example 2, evaluation was performed in the same manner as in Comparative Example 2 except that the electrophotographic photosensitive member 2 was used instead of the electrophotographic photosensitive member 1 used. The results are shown in Table 4.

(Comparative Example 8)
In Comparative Example 3, evaluation was performed in the same manner as Comparative Example 3 except that the electrophotographic photosensitive member 2 was used instead of the used electrophotographic photosensitive member 1. The results are shown in Table 4.
(Comparative Example 9)
In Comparative Example 4, evaluation was performed in the same manner as Comparative Example 4 except that the electrophotographic photosensitive member 2 was used instead of the used electrophotographic photosensitive member 1. The results are shown in Table 4.
(Comparative Example 10)
In Comparative Example 5, evaluation was performed in the same manner as in Comparative Example 5 except that the electrophotographic photosensitive member 2 was used instead of the electrophotographic photosensitive member 1 used. The results are shown in Table 4.

From Table 4, when the wavelength of the static elimination light is less than 500 nm (Examples 3 and 4), the exposure after repeated use is compared with the case where a longer wavelength is used (Comparative Examples 6 to 8). It can be seen that the increase in the partial potential is small. In particular, when the thickness is less than 450 nm (Example 3), it can be seen that the effect is more remarkable than Example 4. Further, when the emission distribution is wide and a component of long wavelength light of 500 nm or more is included (Comparative Example 9), a clear effect as in the example is not obtained. In addition, when two types of light sources having different exposure wavelengths are used (Comparative Example 10), it can be seen that the effect of charge removal by the short wavelength light source is reduced.

(Photoreceptor Preparation Example 3)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge generation layer coating solution (Dispersion 1) in Photoconductor Preparation Example 1 was changed to Dispersion 3 (referred to as electrophotographic photoconductor 3). .
(Photosensitive member production example 4)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 1 except that the charge generation layer coating solution (Dispersion 1) in Photoconductor Preparation Example 1 was changed to Dispersion 4 (referred to as electrophotographic photoconductor 4). .
(Example 5)
Evaluation was performed using the electrophotographic photosensitive member 3 instead of the electrophotographic photosensitive member 1 under the same conditions as in Example 1. In addition, after outputting 50,000 images, a solid white image was output to evaluate the background stain. The results are shown in Table 5 together with the results of Examples 1 and 3.
(Example 6)
Evaluation was performed using the electrophotographic photosensitive member 4 instead of the electrophotographic photosensitive member 1 under the same conditions as in Example 1. In addition, after outputting 50,000 images, a solid white image was output to evaluate the background stain. The results are shown in Table 5.
For the background dirt evaluation, a rank evaluation was performed from the number and size of sunspots generated on the background. The ranking was performed in four stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x.

From Table 5, when the average particle size of the coating liquid used for the charge generation layer is 0.25 μm or less (Examples 3, 5 and 6), the surface potential of the exposed portion in the initial state of the photoreceptor can be lowered, It can be seen that after repeated use, the occurrence of background contamination can be suppressed without affecting the increase in potential of the exposed portion.

(Photoreceptor Preparation Example 5)
It was produced in the same manner as in Photoreceptor Production Example 1 except that the protective layer production conditions in Photoreceptor Production Example 1 were as follows (referred to as Photoreceptor 5).
CH ₄ flow rate: 100 sccm
H ₂ flow rate: 200 sccm
N ₂ flow rate: 35 sccm
Reaction pressure: 0.02 torr
First alternating voltage output: 100 W 13.56 MHz
Bias voltage (DC component): -150V
As a result of XPS analysis of the produced protective layer, it was confirmed that nitrogen contained in the protective layer.

(Photosensitive member preparation example 6)
It was produced in the same manner as in Photoreceptor Production Example 1 except that the protective layer production conditions in Photoreceptor Production Example 1 were as follows (referred to as Photoreceptor 6).
C ₂ H ₄ flow rate: 100 sccm
H ₂ flow rate: 50 sccm
C ₂ F ₆ flow rate: 100 sccm
Reaction pressure: 0.01 torr
First alternating voltage output: 100 W 13.56 MHz
Bias voltage (DC component): -200V
As a result of XPS analysis of the produced protective layer, it was confirmed that the protective layer contained fluorine.

(Photoreceptor Preparation Example 7)
It was produced in the same manner as in Photoreceptor Production Example 1 except that the protective layer production conditions in Photoreceptor Production Example 1 were as follows (referred to as Photoreceptor 7).
C ₂ H ₄ flow rate: 90 sccm
H ₂ flow rate: 200 sccm
PH ₃ flow rate: 45sccm
Reaction pressure: 0.02 torr
First alternating voltage output: 100 W 13.56 MHz
Bias voltage (DC component): -150V
As a result of XPS analysis of the produced protective layer, it was confirmed that phosphorus contained in the protective layer.

(Photoreceptor Preparation Example 8)
It was produced in the same manner as in Photoreceptor Production Example 1 except that the protective layer production conditions in Photoreceptor Production Example 1 were as follows (referred to as Photoreceptor 8).
C ₂ H ₄ flow rate: 90 sccm
H ₂ flow rate: 200 sccm
CH ₃ Cl flow rate: 50 sccm
Reaction pressure: 0.01 torr
First alternating voltage output: 100 W 13.56 MHz
Bias voltage (DC component): -150V
As a result of XPS analysis of the prepared protective layer, it was confirmed that chlorine was contained in the protective layer.

(Photoreceptor Preparation Example 9)
It was produced in the same manner as in Photoreceptor Production Example 1 except that the protective layer production conditions in Photoreceptor Production Example 1 were as follows (referred to as Photoreceptor 9).
C ₂ H ₄ flow rate: 90 sccm
H ₂ flow rate: 200 sccm
CH ₃ Br flow rate: 30 sccm
Reaction pressure: 0.02 torr
First alternating voltage output: 100 W 13.56 MHz
Bias voltage (DC component): -150V
As a result of XPS analysis of the produced protective layer, it was confirmed that bromine contained in the protective layer.

(Examples 7 to 11)
Evaluation was performed in the same manner as in Example 1 except that the photosensitive members 5 to 9 were used instead of the photosensitive member 1 used in Example 1. The results are shown in Table 6 together with the results of Example 1.
(Comparative Examples 11-15)
Evaluation was performed in the same manner as in Comparative Example 1 except that the photosensitive members 5 to 9 were used instead of the photosensitive member 1 used in Comparative Example 1. The results are shown in Table 6 together with the results of Comparative Example 1.

Table 6 shows that the protective layer has at least one element selected from the group consisting of nitrogen, fluorine, phosphorus, chlorine, and bromine (Examples 7 to 11), and does not have (Example 1). Thus, it can be seen that the exposure portion potential can be reduced.

(Photoreceptor Preparation Example 10)
The intermediate layer in the photoreceptor preparation example 1 has a laminated structure of a charge blocking layer and a moire preventing layer. Photoconductor Preparation Example 1 except that the charge blocking layer coating solution and the moire prevention layer coating solution having the following composition were applied and dried to obtain a 1.0 μm charge blocking layer and a 3.5 μm moire prevention layer. Similarly, a photoconductor was prepared (referred to as electrophotographic photoconductor 10).
◎ Charge blocking layer coating solution
N-methoxymethylated nylon (Lead City: Fine Resin FR-101) 4 parts Methanol 70 parts n-Butanol 30 parts ◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0) 126 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dainippon Ink & Chemicals, Inc.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1.5 / 1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Photoreceptor Preparation Example 11)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 10 except that the thickness of the charge blocking layer was 0.3 μm in Photoconductor Preparation Example 10 (referred to as electrophotographic photoconductor 11).
(Photoconductor Preparation Example 12)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 10 except that the thickness of the charge blocking layer was 1.8 μm in Photoconductor Preparation Example 10 (referred to as electrophotographic photoconductor 12).
(Photoreceptor Preparation Example 13)
In Photoconductor Preparation Example 10, a photoconductor was prepared in the same manner as in Photoconductor Preparation Example 10 except that the charge blocking layer coating solution was changed to one having the following composition (referred to as electrophotographic photoconductor 13).
◎ Charge blocking layer coating solution Alcohol-soluble nylon (Toray: Amilan CM8000) 4 parts Methanol 70 parts n-Butanol 30 parts

(Photoreceptor Preparation Example 14)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 10 except that the moire-preventing layer coating solution was changed to one having the following composition in Photoconductor Preparation Example 10 (referred to as electrophotographic photoconductor 14).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 252 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 3/1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Photoreceptor Preparation Example 15)
A photoconductor was prepared in the same manner as in Photoconductor Preparation Example 10 except that the moire-preventing layer coating solution was changed to that of the following composition in Photoconductor Preparation Example 10 (referred to as electrophotographic photoconductor 15).
◎ Moire prevention layer coating solution Titanium oxide (CR-EL: manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.25 μm) 84 parts Alkyd resin [Beckolite M6401-50-S (solid content 50%),
Dainippon Ink & Chemicals, Inc.] 33.6 parts Melamine resin [Super Becamine L-121-60 (solid content 60%),
Dai Nippon Ink Chemical Co., Ltd.] 18.7 parts 2-butanone 100 parts In the above composition, the volume ratio of the inorganic pigment to the binder resin is 1/1.
The ratio of alkyd resin to melamine resin is a 6/4 weight ratio.

(Example 12)
The electrophotographic photosensitive member 10 produced as described above is mounted on an image forming apparatus as shown in FIG. 10, the image exposure light source is a semiconductor laser of 780 nm (image writing by a polygon mirror), a scorotron charger as a charging member, a transfer member A transfer belt was used as a member, and a 428 nm LED (Rohm: half-value width: 65 nm) was used as a static elimination light source. The process conditions before the test were set as follows, and 50,000 sheets were continuously printed using a chart with a writing rate of 6%.
Photoconductor charging potential (unexposed portion potential): −900 V
Development bias: -650V (negative / positive development)
Surface potential after neutralization (unexposed area of writing light): −100V

<Evaluation items>
(1) Measurement of surface potential Evaluation was made by measuring the potential of a photosensitive member exposed part before and after printing 50,000 images.
As a measurement method, a surface potential meter is mounted at the position of the developing portion shown in FIG. The partial potential was measured. The results are shown in Table 7.
(2) Soil evaluation Further, after outputting 50,000 images (after the completion of the surface potential measurement), a solid white image was output to evaluate the soil (22 ° C.-50% RH). The background dirt evaluation was performed by the above-described four-level rank evaluation. The results are shown in Table 7.
(3) Evaluation of cleaning property Further, after evaluation of soiling, under a low temperature and low humidity environment (10 ° C., 15% RH), using a test chart as shown in FIG. The image was output in the direction from solid to white, 50 sheets were continuously printed, and the cleaning property was evaluated. At this time, the image of the 50th white solid portion was visually evaluated. Evaluation is performed in 4 stages, ◎ for very good (no cleaning failure at all), ◯ for good (level with slight black streaks, 1 to 2 in the longitudinal direction), slightly inferior (slightly) A black streak level (3-4 places in the longitudinal direction) was represented by Δ, and a very bad one (level where black streaks clearly entered) was represented by x. The results are shown in Table 7.

(4) Dot reproducibility evaluation Subsequent to the previous cleaning test, a further sheet passing test (used with the previous 6% char) was conducted in a high temperature and high humidity environment (30 ° C.-90% RH). A one-dot image evaluation (outputting an image in which independent dots were written) was performed after passing the sheet. A one-dot image was observed with an optical microscope, and the clarity of the dot outline was ranked. The rank evaluation was performed in four stages, and very good ones were indicated by ◎, good ones by ○, slightly inferior by Δ, and very bad by x. The results are shown in Table 7.
(5) Wear amount evaluation The initial film thickness of the photoconductor was measured, and the film thickness was measured again after completing the above tests (1) to (4). The difference in film thickness (amount of wear) before and after all tests was evaluated. The film thickness was measured at intervals of 1 cm, excluding 5 cm at both ends in the longitudinal direction of the photoreceptor, and the average value was taken as the film thickness.

(Examples 13 to 17)
Under the same conditions as in Example 12, the electrophotographic photoreceptors 11 to 15 produced as described above were evaluated. The results are shown in Table 7. Table 7 also shows the electrophotographic photosensitive member numbers used corresponding to the example numbers.
From the results in Table 7, it can be seen that the durability against soiling is improved by making the intermediate layer a charge blocking layer and a moire preventing layer.

(Example 18)
In Example 1, evaluation was performed in the same manner as in Example 1 except that the image exposure light source was changed to a 407 nm semiconductor laser (manufactured by Nichia). The results are shown in Table 8 together with the case of Example 1.
Further, a one-dot image having a diameter of 60 μm was formed and compared with the case of Example 1 (the dot formation state was observed with a 150 × microscope).
From Table 8, it can be seen that when writing is performed using a short wavelength LD (407 nm) (Example 18), the increase in the potential of the exposed area is further suppressed as compared with Example 1. Furthermore, in dot evaluation, the outline of the one-dot image of Example 18 was clearer.

(Photoreceptor Production Example 16)
Similar to Photoreceptor Preparation Example 1 except that the charge generation layer coating solution (Dispersion 1) in Photoreceptor Preparation Example 1 was changed to Dispersion 5 and the charge transport layer coating solution was changed to the following composition. An electrophotographic photosensitive member was prepared (referred to as an electrophotographic photosensitive member 16).
◎ Charge transport layer coating solution Polycarbonate (TS2050: manufactured by Teijin Chemicals Ltd.) 10 parts Charge transport material of the following structural formula 7 parts
80 parts of methylene chloride

Example 19
The previously produced electrophotographic photosensitive member 16 is mounted on a process cartridge as shown in FIG. 12, mounted in an image forming apparatus as shown in FIG. 11, and an image exposure light source is a 655 nm semiconductor laser (image writing by a polygon mirror). ), A contact roller charger was used as the charging member, a transfer belt was used as the transfer member, and a 428 nm LED (manufactured by ROHM: full width at half maximum: 65 nm) was used as the charge eliminating light source. Process conditions before the test are set as follows, and a chart with a writing rate of 6% (characters equivalent to 6% as an image area are written on the entire A4 surface) is continuously 50,000. Sheet printing was performed.
Photoconductor charging potential (unexposed portion potential): −900 V
Development bias: -650V (negative / positive development)
Surface potential after neutralization (unexposed area of writing light): −100V
In the evaluation, the photosensitive member exposed portion potential was measured before and after printing 50,000 images (black station).
As a measuring method, a surface potential meter is mounted at the developing portion position shown in FIG. 12, and after charging the photosensitive member to −900 V, solid writing is performed with the semiconductor laser, and the surface potential of the unexposed portion at the developing portion and the exposure are measured. The partial potential was measured. The results are shown in Table 9.
Further, before and after printing 50,000 sheets, an ISO / JIS-SCID image N1 (portrait) was output to evaluate the color color reproducibility.

(Example 20)
The evaluation was performed in the same manner as in Example 19 except that the charge removal light source in Example 19 was changed to a 472 nm LED (manufactured by Seiwa Denki: full width at half maximum of 15 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 19. The results are shown in Table 9.
(Comparative Example 16)
Evaluation was performed in the same manner as in Example 19 except that the neutralization light source in Example 19 was changed to 502 nm LED (manufactured by Seiwa Denki: full width at half maximum of 15 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 19. The results are shown in Table 9.
(Comparative Example 17)
Evaluation was performed in the same manner as in Example 19 except that the static elimination light source in Example 19 was changed to a 591 nm LED (Rohm: half width: 15 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 19. The results are shown in Table 9.
(Comparative Example 18)
Evaluation was performed in the same manner as in Example 19 except that the static elimination light source in Example 19 was changed to 630 nm LED (Rohm: half width 20 nm). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 19. The results are shown in Table 9.

(Comparative Example 19)
Evaluation was performed in the same manner as in Example 19 except that the static elimination light source in Example 19 was changed to a fluorescent lamp (having the emission spectrum shown in FIG. 1). The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 19. The results are shown in Table 9.
(Comparative Example 20)
Except for changing to irradiate substantially the same amount of light simultaneously using two 428 nm LEDs (Rohm: half width 65 nm) and 630 nm LEDs (Rohm: half width 20 nm) as the static elimination light source in Example 19 Evaluation was carried out in the same manner as in 19. The amount of charge removed was adjusted so that the surface potential of the photoreceptor after charge removal would be the same as in Example 19. The results are shown in Table 9.

From Table 9, when the wavelength of static elimination light is less than 500 nm (Examples 19 and 20), exposure after repeated use is compared with the case where longer wavelengths are used (Comparative Examples 16 to 18). It can be seen that the increase in the partial potential is small. Furthermore, when it is less than 450 nm (Example 19), it can be seen that the effect is further remarkable.
Further, in the case where the light emission distribution is wide and a component of long wavelength light of 500 nm or more is included (Comparative Example 19), the clear effect as in the example is not obtained. In addition, when two types of light sources having different exposure wavelengths are used (Comparative Example 20), it can be seen that the effect of charge removal by the short wavelength light source is reduced.
From the results of the test chart, in Examples 19 and 20, an image almost the same as the initial image was output even after printing 50,000 sheets, but in Comparative Examples 16 to 20, after printing 50,000 sheets , The image was slightly out of color balance.

(Photoreceptor Preparation Example 17)
An electrophotographic photosensitive member was prepared in the same manner as in the photosensitive member preparation example 16 except that the charge generation layer coating liquid (dispersion liquid 5) in the photosensitive member preparation example 16 was changed to the dispersion liquid 6 (referred to as an electrophotographic photosensitive member 17). ).
(Example 21)
In Example 19, evaluation was performed in the same manner as in Example 19 except that the electrophotographic photosensitive member 17 was used instead of the used electrophotographic photosensitive member 16. The results are shown in Table 10.
(Example 22)
In Example 20, evaluation was performed in the same manner as in Example 20 except that the electrophotographic photosensitive member 17 was used instead of the used electrophotographic photosensitive member 16. The results are shown in Table 10.
(Comparative Example 21)
In Comparative Example 16, evaluation was performed in the same manner as Comparative Example 16 except that the electrophotographic photosensitive member 17 was used instead of the used electrophotographic photosensitive member 16. The results are shown in Table 10.

(Comparative Example 22)
In Comparative Example 17, evaluation was performed in the same manner as Comparative Example 17 except that the electrophotographic photosensitive member 17 was used instead of the used electrophotographic photosensitive member 16. The results are shown in Table 10.
(Comparative Example 23)
In Comparative Example 18, evaluation was performed in the same manner as Comparative Example 18 except that the electrophotographic photosensitive member 17 was used instead of the used electrophotographic photosensitive member 16. The results are shown in Table 10.
(Comparative Example 24)
In Comparative Example 19, evaluation was performed in the same manner as in Comparative Example 19 except that the electrophotographic photosensitive member 17 was used instead of the used electrophotographic photosensitive member 16. The results are shown in Table 10.
(Comparative Example 25)
In Comparative Example 20, evaluation was performed in the same manner as Comparative Example 20 except that the electrophotographic photosensitive member 17 was used instead of the used electrophotographic photosensitive member 16. The results are shown in Table 10.

From Table 10, when the wavelength of the static elimination light is less than 500 nm (Examples 21 and 22), the exposure after repeated use is compared with the case where a longer wavelength is used (Comparative Examples 21 to 23). It can be seen that the increase in the partial potential is small. Furthermore, when it is less than 450 nm (Example 21), it can be seen that the effect is further remarkable.
Further, in the case where the emission distribution is wide and a component of long wavelength light of 500 nm or more is included (Comparative Example 24), the clear effect as in the example is not obtained. In addition, when two types of light sources having different exposure wavelengths are used (Comparative Example 25), it can be seen that the effect of charge removal by the short wavelength light source is reduced.
From the results of the test chart, in Examples 21 and 22, an image almost the same as the initial image was output even after printing 50,000 sheets, but in Comparative Examples 21 to 25, after printing 50,000 sheets. , The image was slightly out of color balance.
Moreover, when the exposed part surface potential of Example 19 described in Table 9 and the exposed part surface potential of Example 21 described in Table 10 are compared, the exposed part surface potential of Example 19 is lower. It can be seen that the asymmetry of the coupler component of the azo pigment used in Example 19 contributes to higher sensitivity.

(Example 23)
In Example 19, the evaluation was performed in the same manner as in Example 19 except that the image exposure light source was changed to a 407 nm semiconductor laser (manufactured by Nichia). The results are shown in Table 11 together with the case of Example 19.
Further, a one-dot image having a diameter of 60 μm was formed and compared with the case of Example 19 (the dot formation state was observed with a 150 × microscope).
From Table 11, it can be seen that when writing is performed using the short wavelength LD (407 nm) (Example 23), the exposure portion potential rise is further suppressed as compared to Example 19. Furthermore, in dot evaluation, the outline of the one-dot image of Example 23 was clearer.

Spectral emission spectrum of fluorescent lamp Conceptual diagram of the photocarrier generation mechanism of organic materials Conceptual diagram of photocarrier generation mechanism of inorganic materials It is a figure showing the layer structure of the electrophotographic photosensitive member used for this invention. It is a figure showing another layer structure of the electrophotographic photosensitive member used for this invention. It is a figure showing another layer structure of the electrophotographic photosensitive member used for this invention. It is a figure which shows the state of the dispersion liquid when dispersion time is short. It is a figure which shows the state of the dispersion liquid when dispersion time is long. It is a figure which shows an average particle diameter and a particle size distribution about the dispersion liquid of FIG. 1 is a schematic view for explaining an electrophotographic process and an image forming apparatus of the present invention. 1 is a schematic view for explaining a tandem-type full-color image forming apparatus of the present invention. FIG. FIG. 4 is a diagram for explaining a process cartridge for an image forming apparatus according to the present invention. 4 is a diagram illustrating an XD spectrum of titanyl phthalocyanine synthesized in Synthesis Example 1. FIG. It is a figure showing the XD spectrum of the dry powder of the water paste (wet cake). Explanatory drawing of the specific example of the plasma CVD apparatus used when forming a protective layer. The top view of the frame-shaped structure 102 of the said plasma CVD apparatus. The top view of the frame-shaped structure 102 of the said plasma CVD apparatus. 10 is a test chart used in Example 12. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Static elimination lamp 3 Charging member 5 Image exposure part 6 Developing unit 8 Registration roller 9 Transfer paper 10 Transfer charger 11 Separation charger 12 Separation claw 14 Fur brush 15 Cleaning blades 16Y, 16M, 16C, 16K Photoconductors 17Y, 17M, 17C, 17K Charging members 18Y, 18M, 18C, 18K Exposure portions 19Y, 19M, 19C, 19K Development members 20Y, 20M, 20C, 20K Cleaning members 21Y, 21M, 21C, 21K Transfer brush 22 Transfer conveyance belt 23 Registration roller 24 Fixing Apparatus 25Y, 25M, 25C, 25K Image forming element 26 Transfer paper 27Y, 27M, 27C, 27K Static elimination member

DESCRIPTION OF SYMBOLS 201 Photoconductor 202 Charging means 203 Exposure 204 Development means 205 Transfer body 206 Transfer means 207 Cleaning means 208 Static elimination means 31 Conductive support 35 Charge generation layer 37 Charge transport layer 39 Intermediate layer 41 Protective layer 43 Charge blocking layer 45 Moire prevention layer 101-0 to 101-n support
102 Frame-like structure
103, 113 electrodes
104, 114 Matching transformer end
105 Transformer output side midpoint
107 vacuum chamber
108, 118 Food
109 Gate valve
115 power supply
116-1, 116-2 matching transformer
117 power supply
120 Exhaust system
121 Adjustment valve
122 turbo molecular pump
123 Rotary pump
125 Gas introduction nozzle
126 Phase adjuster
130-134 gas line
140 AC power supply system
150 reactor

Claims (16)

  An electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and developing the electrostatic latent image with toner to form a visible image Developing means, transfer means for transferring the visible image to a recording medium, fixing means for fixing the transferred image transferred to the recording medium, and static elimination means for eliminating static charge from the electrostatic latent image carrier And the static eliminator is a static eliminator that irradiates light having a wavelength shorter than 500 nm, and the electrostatic latent image carrier is formed on the support and the support. A diamond-like carbon having at least a photosensitive layer comprising a charge generation layer and a charge transport layer, and further having a protective layer on the photosensitive layer, the charge generation layer containing an organic charge generation material, and the protective layer containing hydrogen. An image forming apparatus having an amorphous carbon structure.   The image forming apparatus according to claim 1, wherein the protective layer further includes at least one element selected from the group consisting of nitrogen, fluorine, phosphorus, chlorine, and bromine. The image forming apparatus according to claim 1, wherein the organic charge generating material is an azo pigment represented by the following formula (I).
In the formula, Cp ₁ and Cp ₂ represent coupler residues. R ₂₀₁ and R ₂₀₂ each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a cyano group, and may be the same or different. Cp ₁ and Cp ₂ are represented by the following formula (II):
In the formula, R ₂₀₃ represents a hydrogen atom, an alkyl group, or an aryl group. _R204 , _R205 , _R206 , _R207 , and _R208 each represent a hydrogen atom, a nitro group, a cyano group, a halogen atom, a halogenated alkyl group, an alkyl group, an alkoxy group, a dialkylamino group, or a hydroxyl group; A group of atoms necessary for constituting a substituted or unsubstituted aromatic carbocyclic ring or a substituted or unsubstituted aromatic heterocyclic ring. The image forming apparatus according to claim 3, wherein Cp ₁ and Cp ₂ of the azo pigment are different from each other.   The organic charge generating material has a maximum diffraction peak at 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray of CuKα, and further, 9.4 °, 9.6 °, It has a main peak at 24.0 °, a peak at 7.3 ° as the lowest diffraction peak, and a peak between the 7.3 ° peak and the 9.4 ° peak. The image forming apparatus according to claim 1, further comprising a titanyl phthalocyanine crystal having no peak at 26.3 °.   6. The latent image carrier according to claim 1, wherein an intermediate layer is provided between the support and the charge generation layer, and the intermediate layer includes a charge blocking layer and a moire prevention layer. Image forming apparatus.   The image forming apparatus according to claim 6, wherein the charge blocking layer is made of an insulating material and has a film thickness of less than 2.0 μm and 0.3 μm or more.   The image forming apparatus according to claim 6, wherein the moire preventing layer contains an inorganic pigment and a binder resin, and a volume ratio of the two is in a range of 1/1 to 3/1.   9. The image forming apparatus according to claim 1, wherein an exposure light source wavelength used in the electrostatic latent image forming unit is a light source having a wavelength shorter than 450 nm.   The image forming apparatus according to claim 1, comprising a plurality of image forming elements having at least an electrostatic latent image carrier, an electrostatic latent image forming unit, a developing unit, a transfer unit, and a charge eliminating unit.   The electrostatic latent image carrier and one or more means selected from an electrostatic latent image forming means, a developing means, a charge eliminating means, and a cleaning means are integrated, and a process cartridge that is detachable from the apparatus main body is mounted. The image forming apparatus according to claim 1.   An electrostatic latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image carrier, and developing the electrostatic latent image with toner to form a visible image Developing means, transfer means for transferring the visible image to the recording medium, fixing means for fixing the transferred image transferred to the recording medium, and static elimination means for photo-staticizing the residual charge of the electrostatic latent image carrier The static eliminator is a static eliminator that irradiates light having a wavelength shorter than 500 nm, and the electrostatic latent image carrier is composed of a support and at least a charge on the support. A photosensitive layer comprising a generation layer and a charge transport layer, a protective layer on the photosensitive layer, an organic charge generation material in the charge generation layer, and the protective layer containing hydrogen-containing diamond-like carbon and / or Or a process cartridge characterized by an amorphous carbon structure. .   The process cartridge according to claim 12, wherein an exposure light source wavelength used in the electrostatic latent image forming unit is a light source having a wavelength shorter than 450 nm.   An electrostatic latent image forming step of forming an electrostatic latent image on the electrostatic latent image carrier, a developing step of developing the electrostatic latent image with toner to form a visible image, and the visible image An image forming method having at least a transfer step for transferring the image to a recording medium, a fixing step for fixing the transferred image transferred to the recording medium, and a charge eliminating step for photostatic discharge of residual charges on the electrostatic latent image carrier. The static elimination step is a static elimination step of irradiating light having a wavelength shorter than 500 nm, and the electrostatic latent image carrier comprises a support, and at least a charge generation layer and a charge transport layer on the support. The photosensitive layer further has a protective layer on the photosensitive layer, the charge generation layer contains an organic charge generation material, and the protective layer has a diamond-like carbon and / or amorphous carbon structure containing hydrogen. An image forming method.   The image forming method according to claim 14, wherein an exposure light source wavelength used in the electrostatic latent image forming step is a light source having a wavelength shorter than 450 nm.   The image forming method according to claim 14, comprising a plurality of image forming steps including at least an electrostatic latent image forming step, a developing step, a transfer step, and a charge eliminating step.