JP2016090985A - Electrophotographic device and method for designing electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suggest an electrophotographic device that can output high-quality images when using an electrophotographic photoreceptor having a higher abrasion resistance than an existing photoreceptor in an electrophotographic process with high processing rates.SOLUTION: The electrophotographic device includes: an electrophotographic photoreceptor having a conductive base material, an optical conducting layer, and a surface layer in that order; pre-exposure means conducting static elimination by irradiating the electrophotographic photoreceptor with pre-exposure light; main charging means charging the electrophotographic photoreceptor; latent image formation means forming an electrostatic latent image on a charged surface of the electrophotographic photoreceptor; developing means developing a toner image on the electrostatic latent image; and transfer means transferring the toner image, the pre-exposure light of the pre-exposure means having such a wavelength that a charging capability of the electrophotographic photoreceptor is in the range of not smaller than 0.975 and not larger than 1.000 when the maximum level of the charging capability, which changes in response to variations in the wavelength of the pre-exposure light, is 1.000.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an electrophotographic apparatus and a method for designing an electrophotographic apparatus.

  Among various electrophotographic photoreceptors, electrophotographic photoreceptors (hereinafter also referred to as “photoreceptors”) in which a photoconductive layer (photosensitive layer) composed of an amorphous material is formed on a substrate such as a metal are widely known. Yes. In particular, amorphous silicon electrophotographic photoreceptors produced using film deposition techniques such as chemical vapor deposition (CVD) and physical vapor deposition (PVD) have already been commercialized. The amorphous silicon electrophotographic photosensitive member is hereinafter also referred to as “a-Si photosensitive member”.

  As a basic configuration of the a-Si photosensitive member, for example, in the case of a negatively charged a-Si photosensitive member, a lower blocking layer and hydrogenated amorphous silicon (hereinafter also referred to as a-Si: H) on a substrate such as a metal. A layer structure in which a photoconductive layer, an upper blocking layer, and a surface layer are stacked. Examples of the surface layer used in the a-Si photosensitive member include hydrogenated amorphous silicon carbide (hereinafter also referred to as a-SiC: H), hydrogenated amorphous carbon (hereinafter also referred to as aC: H), and hydrogenated amorphous. Materials such as silicon nitride (hereinafter also referred to as a-SiN: H) are known, and among them, a-SiC: H is a frequently used material.

In addition, as an electrophotographic apparatus using an a-Si photosensitive member, for example, a pre-exposure unit that performs static elimination by irradiating the surface of the a-Si photosensitive member with pre-exposure light, a charging unit that imparts a charge to the photosensitive member, A latent image forming unit that forms an electrostatic latent image on an a-Si photoreceptor by performing image exposure, a developing unit that visualizes the electrostatic latent image with toner, a transfer unit that transfers the latent image to a transfer material, and a transfer An electrophotographic apparatus including a cleaning unit that collects residual toner is known.
The a-Si photosensitive member has a feature that it has excellent wear resistance due to the high hardness of the surface layer. For this reason, it may be used in an electrophotographic apparatus having a high process speed (hereinafter also referred to as PS). Many.

  Generally, when the speed of an electrophotographic apparatus is increased, that is, the PS is increased, the surface potential of the electrophotographic photosensitive member (hereinafter also referred to as charging ability) decreases. This also shortens the time from the pre-exposure means to the charging means, so that the recombination of the photocarriers generated by the pre-exposure becomes insufficient, and the charge provided by the photocarrier remaining in the electrophotographic photosensitive member and the charging means. This is because the dark decay becomes large. For these reasons, the charging ability is reduced by increasing the PS.

  As a method for suppressing a decrease in charging ability in such an electrophotographic apparatus having a fast PS, Patent Document 1 uses a relatively short wavelength of pre-exposure light, thereby suppressing the decrease in charging ability and improving efficiency. It is described that good static elimination can be achieved. This is because when a relatively short wavelength of light is used as pre-exposure, photocarriers can be intensively generated in a region where the permeation distance is relatively short, and generated by pre-exposure when charging is applied by the charging means. It is described that the probability of remaining optical carriers remaining can be reduced.

JP 2010-170111 A

  In recent years, as the speed and color of an electrophotographic apparatus have been increased, the electrophotographic photosensitive member has been changed to an electrophotographic process that is more easily worn than before. In addition, with the colorization of electrophotographic apparatuses, there are increasing demands for improved image quality and stable output of high-quality images. In order to satisfy these requirements, an electrophotographic photosensitive member having higher wear resistance than before and capable of outputting a high-quality image is required.

However, even if an electrophotographic photosensitive member having higher wear resistance than before is mounted on an electrophotographic apparatus in which PS is relatively fast and the wavelength of light for pre-exposure is shortened, sufficient charging ability can be obtained. There was no case.
Therefore, an object of the present invention is to provide an electronic device capable of outputting a high-quality image even in the case of using an electrophotographic photosensitive member having higher wear resistance than in the conventional electrophotographic process having a relatively fast PS. It is to provide a photographic apparatus.

According to the present invention, an electrophotographic photosensitive member in which a photoconductive layer and a surface layer are sequentially formed on a conductive substrate, pre-exposure means for performing static elimination by irradiating the electrophotographic photosensitive member with pre-exposure light, A main charging means for charging the electrophotographic photosensitive member, a latent image forming means for forming an electrostatic latent image on a charging surface of the electrophotographic photosensitive member, and a developing means for developing the electrostatic latent image as a toner image; In an electrophotographic apparatus having transfer means for transferring the toner image,
When the maximum value of the charging ability of the electrophotographic photosensitive member that changes when the pre-exposure means changes the wavelength of the pre-exposure light is 1.000, the charging ability is 0.975 or more and 1.000. An electrophotographic apparatus having the following pre-exposure light wavelength is provided.

  According to the present invention, even when an electrophotographic photoreceptor excellent in abrasion resistance is used in an electrophotographic process having a relatively fast PS, the wavelength of the pre-exposure light suitable for the electrophotographic photoreceptor can be selected. This makes it possible to control the amount of light absorbed by the electrophotographic photosensitive member. Thereby, since charging ability can be improved, an electrophotographic apparatus capable of outputting an image with high speed and high image quality can be provided.

FIG. 2A is a schematic configuration diagram of an electrophotographic apparatus according to the present invention. (B) is the 2nd schematic block diagram of the electrophotographic apparatus concerning this invention. (A) is a 3rd schematic block diagram of the electrophotographic apparatus concerning this invention. (B) is the 4th schematic block diagram of the electrophotographic apparatus concerning this invention. It is a schematic diagram which shows the example of the plasma CVD apparatus used for preparation of an a-Si photoreceptor. (A) is a schematic diagram showing an example of a layer configuration of an a-Si photosensitive member for positive charging. FIG. 6B is a schematic diagram illustrating an example of a layer configuration of a negatively charged a-Si photosensitive member. FIG. 6C is a schematic diagram illustrating a layer configuration of the a-Si photosensitive member used in the description of FIG. 5. It is explanatory drawing which shows the relationship of the light absorption rate in all the layers which exist in the free surface side rather than the photoconductive layer with respect to the wavelength of the light irradiated to an a-Si photoreceptor. FIG. 6 is an explanatory diagram for explaining a change in surface potential of an electrophotographic photosensitive member at a developing device position with respect to a wavelength of pre-exposure light under predetermined electrophotographic process conditions.

As a result of intensive studies, when an electrophotographic photosensitive member having excellent wear resistance is used in an electrophotographic process having a relatively fast PS, a high-quality image can be obtained by using an electrophotographic apparatus that satisfies the following conditions. It was found that can be output.
Pre-exposure having a pre-exposure wavelength in which the charging ability falls within the range of 0.975 or more and 1.000 or less when the charging ability that is the maximum value obtained from the wavelength dependence of the pre-exposure of charging ability is 1.000. Be a means.

Hereinafter, conditions to be satisfied and effects thereof in the electrophotographic apparatus of the present invention will be described.
First, the absorption of light in all layers on the free surface side (hereinafter also referred to as the free surface side layer) from the photoconductive layer when the wavelength of the pre-exposure light irradiated on the a-Si photoconductor is changed. Will be described.

  FIG. 5 is an explanatory diagram showing the relationship of the light absorptance in the layer on the free surface side with respect to the wavelength of light irradiated to the a-Si photosensitive member in the configuration of the a-Si photosensitive member in FIG. is there. In the case of FIG. 4C, the free surface side layer is a surface layer 4205 located on the free surface side of the photoconductive layer, and the free surface side layer is composed of only the surface layer hereinafter. The case will be described.

As shown in FIG. 5, when the a-Si photosensitive member is irradiated with light, the amount of light absorbed by the free surface layer increases as the wavelength of the irradiated light decreases.
Next, the behavior of the photocarrier generated in the electrophotographic photosensitive member based on the change in the surface potential of the electrophotographic photosensitive member when the wavelength of the pre-exposure light irradiated on the a-Si photosensitive member is changed is shown in FIG. 6 will be described.

  FIG. 6 shows changes in the surface potential of the electrophotographic photosensitive member at the position of the developing device when the electrophotographic photosensitive member is mounted on the electrophotographic apparatus and only the wavelength of the pre-exposure light is changed under predetermined electrophotographic process conditions. It is explanatory drawing for demonstrating. Note that the recombination shown below is that the photocarriers are bonded and disappeared, and the bond is that the charge applied from the outside and the photocarriers are combined and disappeared.

  When the a-Si photosensitive member is mounted on an electrophotographic apparatus, when the wavelength of the pre-exposure light is relatively long, the number of photocarriers generated in the free surface layer is small. On the other hand, since the pre-exposure enters the region where the penetration distance is relatively long in the photoconductive layer, the pre-exposure penetrates from the free surface side of the photoconductive layer to the conductive substrate side to a deep range. For this reason, in the photoconductive layer, photocarriers are generated by pre-exposure even in a region far from the free surface. Therefore, when PS is fast, the surface of the electrophotographic photosensitive member irradiated with pre-exposure is moved to the charging unit. Recombination becomes insufficient and a large amount of residual carriers remain in the photoconductive layer. A part of the remaining carrier cannot be combined with the charge applied by the charging unit even while passing under the charging unit. When the remaining carrier is combined with the charge applied by the charging unit after passing through the charging unit, a large dark decay occurs. Inferred.

  As the wavelength of the pre-exposure light is shortened within the region A in FIG. 5, the absorption of light in the free surface layer slightly increases. At the same time, the penetrating distance is shortened by shortening the wavelength, so that the region where photocarriers are generated in the photoconductive layer is narrowed. On the other hand, since the photocarrier density in the region increases, the recombination probability of the photocarriers generated by the pre-exposure is increased while the surface of the electrophotographic photosensitive member irradiated with the pre-exposure moves to the charging means. It increases and the residual carriers in the photoconductive layer also decrease. Thereby, it is presumed that the dark attenuation after passing through the charging means on the surface of the electrophotographic photosensitive member irradiated with the pre-exposure decreases.

  If the wavelength of the pre-exposure light is further shortened, the penetration depth into the photoconductive layer is reduced, and the number of photocarriers remaining in the photoconductive layer is reduced. For this reason, darkness caused by the photoconductive layer is reduced. Attenuation decreases. However, as the wavelength is further shortened, the region starts to shift to the region B in FIG. 5, so that light absorption in the free surface layer increases, and the number of photocarriers generated in the free surface layer increases. Start to increase. The photocarriers generated at this time are less likely to disappear due to recombination before the surface of the electrophotographic photosensitive member irradiated with the pre-exposure is moved to the charging means. Attenuation increases. As a result, the decrease in dark attenuation caused by the photoconductive layer due to the shortening of the wavelength of the pre-exposure light is combined with the increase in dark attenuation caused by the layer on the free surface side. Therefore, as shown in the area D of FIG. 6, when the pre-exposure wavelength is shortened, the charge potential in a predetermined electrophotographic process has a distribution having a maximum value.

  Then, the wavelength of the pre-exposure light is further shortened, and the penetration depth into the photoconductive layer is further reduced at the wavelength of the pre-exposure light in the region B in FIG. The number of carriers will further decrease. On the contrary, as the light absorption in the free surface layer increases rapidly, a large number of optical carriers are generated in the free surface layer. Therefore, if the wavelength of the pre-exposure light is further shortened, the number of photocarriers in the layer on the free surface side is large, and before the surface of the electrophotographic photosensitive member irradiated with the pre-exposure moves to the charging means. It becomes difficult for optical carriers to disappear due to recombination. For this reason, the presence of a large number of photocarriers under the main charging means reduces the influence of dark attenuation caused by the photoconductive layer, but the influence of dark attenuation caused by the free surface layer is dominant. It is assumed that

  For the reasons described above, the charging potential in a predetermined electrophotographic process becomes a maximum value at a certain wavelength of light of pre-exposure as in the region D in FIG. When the wavelength of the pre-exposure light having the maximum value is changed from the wavelength of the pre-exposure light to the longer wavelength side, the surface potential is lowered due to the influence of dark attenuation caused by the photoconductive layer as in the region E in FIG. On the contrary, when the wavelength of the pre-exposure light having the maximum value is changed from the wavelength of short exposure to the short wavelength side, the surface potential is lowered due to the influence of dark attenuation caused by the layer on the free surface side as in the region C in FIG. .

In addition, the presence or absence of the maximum value in the region D in FIG. 6 and the wavelength of the pre-exposure light that becomes the maximum value are the amount of light absorbed in the pre-exposure in the photoconductive layer and the pre-exposure in the layer on the free surface side Determined by the balance of light absorption.
Furthermore, the faster the PS, the greater the influence of the residual carrier described above. In particular, it becomes remarkable when PS is 500 mm / second or more.

For these reasons, in an electrophotographic process with a relatively fast PS, in an electrophotographic apparatus equipped with an a-Si photosensitive member, the pre-exposure conditions are appropriately set according to the characteristics of the mounted a-Si photosensitive member. Without control, it is difficult to output a high-quality image.
Therefore, in the present invention, as a method for controlling the wavelength of the pre-exposure light, the wavelength of the pre-exposure at a predetermined position (for example, the position of the developing device) in the rotation direction of the electrophotographic photosensitive member under predetermined electrophotographic process conditions. Measure the change in charging ability when changing the. Then, the maximum value of the charging ability is calculated from the relationship between the wavelength of the pre-exposure and the charging ability, and the maximum value of the charging ability is set to 1.000. After that, it is necessary to select a pre-exposure wavelength in which the charging ability for each pre-exposure wavelength falls within the range of 0.975 to 1.000 with respect to the maximum value of the charging ability. This makes it possible to realize an electrophotographic apparatus that can output a high-quality image with a long lifetime even with a relatively fast PS.

When the charged potential of the surface of the electrophotographic photosensitive member measured at the predetermined position at the wavelength of the pre-exposure light is smaller than 0.975 with respect to the maximum value of the charged potential, A charged potential suitable for a photographic process may not be obtained.
The conditions for measuring the charged potential on the surface of the electrophotographic photosensitive member by changing the wavelength of the pre-exposure are shown below.

The charging potential on the surface of the electrophotographic photosensitive member may be fixed at a predetermined position in the rotation direction of the electrophotographic photosensitive member even if the wavelength of the pre-exposure light is changed, and there is no restriction on the predetermined position. However, it is preferable to measure at the position of the developing device.
Further, when changing the wavelength of the pre-exposure, at least the rotation speed of the electrophotographic photosensitive member, the charging current and the crid potential supplied to the electrophotographic photosensitive member by the main charging unit, and the irradiation from the pre-exposure unit to the photosensitive member It is necessary to measure the amount of pre-exposure to be fixed at a predetermined value.

Furthermore, in the present invention, the ratio of the pre-exposure light amount absorbed by the free surface layer to the pre-exposure light amount irradiated to the electrophotographic photosensitive member at the wavelength of the pre-exposure light is 25% to 55%, and Further, by using an electrophotographic photoreceptor excellent in abrasion resistance, it is possible to output a higher quality image.
As described above, the area C in FIG. 6 is affected by the amount of light absorbed by the pre-exposure by the layer on the free surface side. For this reason, the ratio of the amount of the pre-exposure absorbed by the free surface layer to the amount of the pre-exposure irradiated to the electrophotographic photosensitive member at the wavelength of the pre-exposure light is 25% or more.

The ratio of the amount of pre-exposure absorbed by the free surface layer to the amount of pre-exposure irradiated to the electrophotographic photosensitive member at the wavelength of the pre-exposure light is preferably 55% or less. Thereby, it is possible to output an image with excellent gradation.
This is because, if the amount of pre-exposure absorbed by the free surface layer is very large, the amount of light carriers generated in the free surface layer increases, so that the light carrier generated in the pre-exposure forms a latent image. It may remain below the means. Due to the influence of the remaining carriers, the resistance of the layer on the free surface side is lowered, so that when the latent image forming means forms a latent image, the latent image spreads, and as a result, the gradation is considered to deteriorate.

  The conditions to be satisfied and the effects thereof in the electrophotographic apparatus of the present invention described above have been described using an electrophotographic photoreceptor in which the free surface side layer shown in FIG. However, even when the electrophotographic photosensitive member in which the free surface side layer shown in FIGS. 4A and 4B is composed of an intermediate layer and a surface layer is used, the a-Si photosensitive member is irradiated. The relationship of the light absorptance in the free surface layer with respect to the wavelength of the emitted light has the same tendency as in FIG. Therefore, even when the electrophotographic photosensitive member shown in FIGS. 4A and 4B is used, the electrophotography when the wavelength of the pre-exposure light irradiated to the a-Si photosensitive member is changed is used. The change in the surface potential of the photoreceptor has the same tendency as in FIG.

Furthermore, even if the layer structure of the free surface side layer is composed of a plurality of layers, the same tendency as the tendency of FIGS. 5 and 6 is obtained.
Hereinafter, the present invention will be described in more detail.

<Electrophotographic photoreceptor usable in the electrophotographic method of the present invention>
The electrophotographic photosensitive member that can be used in the present invention is not particularly limited as long as it has at least a photoconductive layer and a surface layer on a conductive substrate. An electrophotographic photosensitive member that can be used in an ordinary electrophotographic apparatus is used. What is necessary is just to select, for example, an a-Si photoreceptor and an organic photoreceptor.
As an example of the electrophotographic photosensitive member that can be used in the present invention, an a-Si photosensitive member will be described.

FIG. 4 is a schematic diagram for explaining the layer structure of the a-Si photosensitive member. FIG. 4A is a schematic diagram of a positive charging a-Si photoconductor, and FIG. 4B is a schematic diagram of a negative charging a-Si photoconductor.
In the positive charging a-Si photosensitive member 4000 shown in FIG. 4A, a lower charge injection blocking layer 4002 and a photoconductive layer 4003 composed of a-Si: H are formed on a substrate 4001, and a An intermediate layer 4004 and a surface layer 4005 made of SiC: H are sequentially stacked.

  Further, in the negatively charged a-Si photosensitive member 4100 shown in FIG. 4B, a charge injection blocking layer 4102 and a photoreceptive layer 4102 made of a-Si: H are formed on a base 4101, and the light receiving layer 4102 is formed thereon. The upper blocking layer 4104 and the surface layer 4105 made of a-SiC: H are sequentially stacked.

The layer on the free surface side used for the a-Si photoreceptor is not particularly limited, and examples thereof include materials such as a-SiC: H, a-SiN: H, and aC: H. Of these, a-SiC and a-C are preferable from the viewpoint of wear resistance.
Further, all the layers on the free surface side with respect to the photoconductive layer are on the free surface side with respect to the photoconductive layer made of a-Si, and contain constituent atoms not contained in the photoconductive layer. It is a layer. In the positively charged a-Si photosensitive member shown in FIG. 4A, the intermediate layer 4004 and the surface layer 4005 made of a-SiC having carbon atoms not included in the photoconductive layer correspond to this. Similarly, in the negatively charged a-Si photosensitive member shown in FIG. 4B, the upper blocking layer 4104 and the surface layer 4105 made of a-SiC correspond to this.

When the intermediate layer 4004 in FIG. 4A and the upper blocking layer 4104 in FIG. 4B are continuously changing from the photoconductive layer to the surface layer, carbon in the intermediate layer and the upper blocking layer The free surface side is confirmed to be all layers on the free surface side in the present invention, with the content of atoms being confirmed, and the free surface side from the position closest to the photoconductive layer side.
In the present invention, the thickness of the surface layer is more preferably 1.0 μm or more from the viewpoint of the life of the electrophotographic photosensitive member.

(Surface layer)
In the present invention, the method for forming the a-SiC surface layer may be any method as long as it can form a layer that satisfies the above definition. Specific examples include plasma CVD, vacuum deposition, sputtering, and ion plating. Among these, the plasma CVD method is preferable from the viewpoint of easy supply of raw materials.

When the plasma CVD method is selected as the method for forming the a-SiC surface layer, the method for forming the a-SiC surface layer is as follows.
That is, a raw material gas for supplying silicon atoms and a raw material gas for supplying carbon atoms are introduced in a desired gas state into a reaction vessel whose inside can be depressurized, and glow discharge is caused in the reaction vessel. In this way, the source gas introduced into the reaction vessel is decomposed, and a layer composed of a-SiC may be formed on a substrate that is previously set at a predetermined position.

As the source gas for supplying silicon atoms, for example, silanes such as silane (SiH ₄ ) and disilane (Si ₂ H ₆ ) can be preferably used. As the source gas for the carbon atoms supplied, for example, methane _(CH 4), acetylene _(C 2 _{H 2)} gas or the like can be suitably used. Moreover, hydrogen (H ₂ ) may be used together with the above raw material gas mainly for adjusting H / (Si + C + H).
When the a-SiC surface layer of the present invention is formed, the wear resistance tends to be good by reducing the gas flow rate supplied to the reaction vessel, increasing the high-frequency power, or increasing the temperature of the substrate. There is. In practice, these conditions may be set in appropriate combination.

(Photoconductive layer)
In the present invention, the photoconductive layer may be any one as long as it has photoconductive characteristics that can satisfy the performance on electrophotographic characteristics, but from the viewpoint of durability and stability, hydrogenated amorphous silicon. The photoconductive layer comprised by is preferable.
In the present invention, when a photoconductive layer composed of a-Si is used as the photoconductive layer, in order to compensate for dangling bonds in a-Si, halogen atoms can be contained in addition to hydrogen atoms. .

  The total content (H + X) of the hydrogen atom (H) and the halogen atom (X) is 10 atom% with respect to the sum (C + H + X) of the silicon atom (C), the hydrogen atom (H) and the halogen atom (X). It is preferable that it is above, and it is more preferable that it is 15 atomic% or more. On the other hand, it is preferably 30 atomic% or less, and more preferably 25 atomic% or less.

  In the present invention, the photoconductive layer preferably contains atoms for controlling conductivity as required. Atoms for controlling conductivity may be contained in the photoconductive layer in a uniformly distributed state, or there may be a portion containing in a non-uniform distribution state in the film thickness direction. May be.

  As atoms for controlling conductivity, so-called impurities in the semiconductor field can be mentioned. That is, an atom belonging to Group 13 of the periodic table giving p-type conductivity or an atom belonging to Group 15 of the periodic table giving n-type conductivity can be used. Note that atoms belonging to Group 13 of the periodic table are also referred to as “Group 13 atoms” below. In addition, atoms belonging to Group 15 of the periodic table are also referred to as “Group 15 atoms” below.

  Specific examples of the Group 13 atom include a boron atom (B), an aluminum atom (Al), a gallium atom (Ga), an indium atom (In), and a thallium atom (Tl). Among these, a boron atom, an aluminum atom, and a gallium atom are preferable. Specific examples of Group 15 atoms include phosphorus atoms (P), arsenic atoms (As), antimony atoms (Sb), and bismuth atoms (Bi). Among these, a phosphorus atom and an arsenic atom are preferable.

The content of atoms for controlling the conductivity contained in the photoconductive layer is preferably 1 × 10 ⁻² atom ppm or more with respect to silicon atoms (Si), and 5 × 10 ⁻² atom ppm or more. It is more preferable that it is 1 × 10 ⁻¹ atom ppm or more. On the other hand, it is preferably 1 × 10 ⁴ atom ppm or less, more preferably 5 × 10 ³ atom ppm or less, and even more preferably 1 × 10 ³ atom ppm or less.

  In the present invention, the layer thickness of the photoconductive layer is not particularly limited as long as desired electrophotographic characteristics can be obtained, but is preferably 40 μm or more in order to suppress a decrease in charging ability resulting from faster PS. Further, from the viewpoint of the size of the abnormal growth site of a-Si, it is possible to suppress the influence on the image by setting the thickness of the photoconductive layer to 60 μm or less.

The photoconductive layer may be composed of a single layer or a plurality of layers (for example, a charge generation layer and a charge transport layer).
Examples of a method for forming a photoconductive layer composed of a-Si include a plasma CVD method, a vacuum deposition method, a sputtering method, and an ion plating method. Among these, the plasma CVD method is preferable from the viewpoint of easy supply of raw materials.

Hereinafter, a method for forming a photoconductive layer will be described by taking a plasma CVD method as an example.
In order to form the photoconductive layer, a raw material gas for supplying silicon atoms and a raw material gas for supplying hydrogen atoms are introduced into a reaction vessel capable of reducing the pressure in a desired gas state, and glow discharge is performed in the reaction vessel. Wake up. Thus, the source gas introduced into the reaction vessel is decomposed, and a layer composed of a-Si may be formed on a substrate previously set at a predetermined position.

In the present invention, as a source gas for supplying silicon atoms, for example, silanes such as silane (SiH ₄ ) and disilane (Si ₂ H ₆ ) can be preferably used. In addition to the above silanes, for example, hydrogen (H ₂ ) can also be suitably used as the source gas for supplying hydrogen atoms.
In addition, when a photoconductive layer such as the above-described halogen atom, atom for controlling conductivity, carbon atom, oxygen atom, nitrogen atom or the like is included, a gaseous or easily gasifiable substance containing each atom is used. What is necessary is just to use suitably as a material.

(Substrate)
The substrate is not particularly limited as long as it has conductivity and can hold the photoconductive layer formed on the surface and the surface layer, and any substrate may be used. Examples of the material of the substrate include metals such as aluminum, chromium, molybdenum, gold, indium, niobium, tellurium, vanadium, titanium, platinum, palladium, and iron, and alloys thereof (for example, aluminum alloys and stainless steel). Can be mentioned. In addition, an electrically insulating material such as a film or sheet of a resin such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polystyrene, or polyamide, glass, or ceramic can be used. In the case of using an electrically insulating material, the surface of the base on which the photoconductive layer is formed may be subjected to a conductive treatment. Note that a conductive substrate (conductive substrate) is hereinafter also referred to as a “conductive substrate”.

(Charge injection blocking layer)
In the present invention, a charge injection blocking layer having a function of blocking charge injection into the photoconductive layer may be provided. The charge injection blocking layer includes a lower charge injection blocking layer provided between the conductive substrate and the photoconductive layer, and an upper charge injection blocking layer provided between the photoconductive layer and the surface layer.
The lower charge injection blocking layer is a layer having a function of blocking the injection of charges from the substrate to the photoconductive layer when the surface of the electrophotographic photosensitive member is charged with a certain polarity. In order to provide such a function, the lower charge injection blocking layer is based on the material constituting the photoconductive layer, and contains a relatively large number of atoms for controlling conductivity compared to the photoconductive layer. Let

  The upper charge injection blocking layer is a layer having a function of blocking charge injection from the surface layer to the photoconductive layer when the surface of the electrophotographic photosensitive member is subjected to a charging process with a certain polarity. In order to provide such a function, the upper charge injection blocking layer is based on a material that is intermediate between the material constituting the photoconductive layer and the material constituting the surface layer, and is used for controlling the conductivity. Is contained in a relatively large amount as compared with the photoconductive layer and the surface layer.

  The atoms contained in the charge injection blocking layer for controlling conductivity may be contained in the charge injection blocking layer evenly distributed or in a non-uniform distribution state in the film thickness direction. There may be a part contained in If the distribution concentration is non-uniform, it is preferable to contain it so that it is distributed more on the substrate side. In any case, the atoms for controlling the conductivity are contained in the charge injection blocking layer in a uniform distribution in the in-plane direction parallel to the surface of the substrate. preferable.

As atoms to be contained in the charge injection blocking layer for controlling conductivity, group 13 atoms or group 15 atoms can be used depending on the charge polarity.
Further, the charge injection blocking layer can contain at least one atom of carbon atom, nitrogen atom and oxygen atom to improve the adhesion between the charge injection blocking layer and the substrate.

  At least one kind of carbon atom, nitrogen atom and oxygen atom contained in the charge injection blocking layer may be contained in the charge injection blocking layer in a uniformly distributed state, or non-uniformly. There may be a portion contained in a distributed state. In any case, the atoms for controlling the conductivity are contained in the charge injection blocking layer in a uniform distribution in the in-plane direction parallel to the surface of the substrate from the viewpoint of achieving uniform characteristics. preferable.

The film thickness of the charge injection blocking layer is preferably from 0.1 to 10 μm, more preferably from 0.3 to 5 μm from the viewpoint of obtaining desired electrophotographic characteristics and economic effects. More preferably, it is 0.5-3 micrometers. By setting the film thickness to 0.1 μm or more, the charge injection ability from the substrate can be sufficiently obtained, and a preferable charging ability can be obtained. On the other hand, when the thickness is 5 μm or less, it is possible to prevent an increase in manufacturing cost due to the extension of the charge injection blocking layer formation time.
If necessary, a so-called change layer may be provided between the lower charge injection blocking layer and the photoconductive layer, and between the photoconductive layer, the upper charge injection blocking layer, and the surface layer. it can.

(Middle layer)
In the present invention, an intermediate layer may be provided between the photoconductive layer and the surface layer.
The intermediate layer is a layer having a function of improving adhesion between the photoconductive layer and the surface layer and suppressing peeling of the surface layer. In addition, the photoconductive layer is a layer that also protects the photoconductive layer from mechanical stress and also has a function of suppressing crushing.

  The material constituting the intermediate layer is not particularly limited, but in order to provide the above-described function of the intermediate layer, a material that is intermediate between the material constituting the photoconductive layer and the material constituting the surface layer is selected. Better. For example, in the case of an a-Si photoreceptor having an a-SiC surface layer, the intermediate layer should use a-SiC: H, which is lower than C / (Si + C) of the a-SiC surface layer, as a base material. . Further, between the photoconductive layer made of a-Si: H and the surface layer made of a-SiC: H, C / (Si + C) is continuously a-SiC from the photoconductive layer toward the surface layer. You may change so that it may become a surface layer.

<Electrophotographic apparatus according to the present invention>
An electrophotographic method in the color electrophotographic apparatus will be described with reference to a schematic configuration diagram of the color electrophotographic apparatus shown in FIG.
As shown by an arrow in FIG. 1A, the electrophotographic photosensitive member 1001 is rotationally driven, and an intermediate transfer belt (hereinafter also referred to as ITB) 1006 is rotationally driven at the same peripheral speed as the electrophotographic photosensitive member 1001. The electrophotographic photoreceptor 1001 is charged by the primary charger 1002 during the rotation process. Thereafter, the surface of the electrophotographic photosensitive member is irradiated with image exposure light 1003, and an electrostatic latent image (first image) corresponding to a first color component image (for example, a magenta component image) of the target color image is irradiated on the surface of the electrophotographic photosensitive member. 1 latent image) is formed. Next, the second developing device 1004b rotates, and the electrostatic latent image is developed with magenta toner M which is the first color. Then, by applying a primary transfer voltage to the first transfer member 1009 from a high voltage power source (not shown), the first color toner image is transferred to the outer peripheral surface of the ITB 1006. Thereafter, the toner remaining on the surface of the electrophotographic photoreceptor 1001 is removed by the magnet roller 1007 and the cleaning blade 1008 provided in the cleaner 1005. Next, the surface of the electrophotographic photosensitive member is exposed by the charge removing unit 1014 to discharge the electrophotographic photosensitive member.

  Similar to the formation of the first color toner image, a second color toner image (for example, a cyan toner image) and a third color toner image (for example, a yellow toner image) are formed. The three color toner images are sequentially superimposed and transferred onto the surface of the ITB 1006 onto which the first color toner image has been transferred. Finally, a fourth color toner image (for example, a black toner image) is developed by the first developing device 1004a and is superimposed and transferred onto the ITB 1006 to form a color toner image corresponding to the target color image. This color toner image is transferred to the recording material 1013 conveyed by the conveying means 1012 by applying a secondary transfer voltage to the second transfer member 1010 by a high voltage power supply (not shown). The recording material 1013 is guided to a fixing device (not shown), where a toner image is fixed on the recording material 1013. The ITB 1006 after the transfer is cleaned by the ITB cleaner 1011, the transfer residual toner on the ITB is removed, and a series of electrophotographic processes is completed.

The configuration of the electrophotographic apparatus in the present invention is required to have an electrophotographic photosensitive member and at least a pre-exposure unit, a main charging unit, a front latent image forming unit, a developing unit, and a transfer unit. Further, if necessary, a cleaning unit for removing toner remaining on the surface of the electrophotographic photosensitive member after transfer, a pre-transfer charging unit, or the like may be provided.
In the present invention, for the reasons described above, the effect of the present invention becomes more remarkable as the PS becomes faster. Therefore, the effect of the present invention is exhibited by setting PS to 500 mm / second or more, and the effect of the present invention is exhibited more significantly by setting PS to 600 mm / second or more.

Further, as shown in FIG. 1B, a cleaning unit is provided on the downstream side of the transfer unit and the upstream side of the main charging unit with respect to the rotation direction of the electrophotographic photosensitive member. It is preferable to have pre-exposure means on the upstream side with respect to the rotation direction of the body.
As a result, even if the PS becomes faster, it takes a longer time for the surface of the electrophotographic photosensitive member irradiated with the pre-exposure to move from the pre-exposure means to the charging means. Probability increases. For this reason, the probability of recombination with the charge imparted by the charging means is reduced, so that it is possible to reduce the dark decay of the photocarrier generated in the electrophotographic photosensitive member, and the charging ability when the wavelength of the pre-exposure light is shortened. It is easy to obtain the effect of improvement. Furthermore, the probability of recombination of the photocarriers generated by the pre-exposure is increased, so that even when the surface of the electrophotographic photosensitive member irradiated with the pre-exposure reaches under the electrostatic latent image means, the layer on the free surface side Since the optical carriers remaining in the inside are reduced, it is also possible to suppress a reduction in gradation.

However, the pre-exposure unit may not be disposed further upstream with respect to the rotation direction of the electrophotographic photosensitive member. If the pre-exposure unit is installed between the developing unit and the transfer unit, depending on the output image, In some cases, the history of the electrostatic latent image cannot be erased due to the toner on the surface of the photoconductor. As a result, image defects may occur.
For this reason, it is preferable that the pre-exposure unit is installed at a position downstream of the transfer unit and close to the transfer unit with respect to the rotation direction of the electrophotographic photosensitive member.

<Manufacturing apparatus and manufacturing method for manufacturing the electrophotographic photosensitive member of the present invention>
As an example of an electrophotographic photosensitive member that can be used in the present invention, a method for forming an a-Si photosensitive member is described below.
FIG. 3 is a diagram showing an example of a plasma CVD apparatus used for producing an electrophotographic photosensitive member.
This apparatus is roughly composed of a deposition apparatus 3100 having a reaction vessel 3110, a source gas supply device 3200, and an exhaust device (not shown) for depressurizing the inside of the reaction vessel 3110.

  In the reaction vessel 3110, a conductive substrate 3112, a conductive substrate heating heater 3113, and a source gas introduction pipe 3114 connected to the ground are installed. Further, a high frequency power source 3120 is connected to the cathode electrode 3111 insulated by the insulating material 3121 via a high frequency matching box 3115.

A source gas supply device 3200 includes source gas cylinders 3221 to 3225, valves 3231 to 3235, pressure regulators 3261 to 3265, inflow valves 3241 to 3245, such as SiH ₄ , H ₂ , CH ₄ , NO, and B ₂ H ₆ . It consists of outflow valves 3251-3255 and mass flow controllers 3211-3215. A gas cylinder filled with each source gas is connected to a source gas introduction pipe 3114 in the reaction vessel 3110 via an auxiliary valve 3260 and a gas pipe 3116.

  Next, a method for forming a deposited film using this apparatus will be described. First, a conductive substrate 3112 that has been degreased and washed in advance is placed in the reaction vessel 3110 via a cradle 3123. Next, an exhaust device (not shown) is operated to exhaust the reaction vessel 3110. While viewing the display of the vacuum gauge 3119, when the pressure in the reaction vessel 3110 reaches a predetermined pressure of, for example, 1 Pa or less, power is supplied to the heater 3113 for heating the substrate, and the conductive substrate 3112 is moved from 50 ° C. to 350 ° C., for example. Heat to the desired temperature of ° C. At this time, an inert gas such as Ar or He can be supplied from the gas supply device 3200 to the reaction vessel 3110 and heated in an inert gas atmosphere.

  Next, a gas used to form a deposited film is supplied from the gas supply device 3200 to the reaction vessel 3110. That is, if necessary, the valves 3231 to 3235, the inflow valves 3241 to 3245, and the outflow valves 3251 to 3255 are opened, and the flow rate is set in the mass flow controllers 3211 to 3215. When the flow rate of each mass flow controller is stabilized, the main valve 3118 is operated while viewing the display of the vacuum gauge 3119 to adjust the pressure in the reaction vessel 3110 to a desired pressure. When a desired pressure is obtained, high frequency power is applied from the high frequency power source 3120 and at the same time, the high frequency matching box 3115 is operated to generate plasma discharge in the reaction vessel 3110. Thereafter, the high frequency power is quickly adjusted to a desired power, and a deposited film is formed.

  When the formation of the predetermined deposited film is finished, the application of the high frequency power is stopped, the valves 3231 to 3235, the inflow valves 3241 to 3245, the outflow valves 3251 to 3255, and the auxiliary valve 3260 are closed, and the supply of the source gas is finished. At the same time, the main valve 3118 is fully opened, and the reaction vessel 3110 is exhausted to a pressure of 1 Pa or less.

The formation of the deposited layers is completed as described above. When a plurality of deposited layers are formed, the above procedure is repeated again to form each layer. The bonding region can also be formed by changing the raw material gas flow rate and pressure to the conditions for forming the photoconductive layer in a certain time.
After all the deposited films are formed, the main valve 3118 is closed, the leak valve 3117 is opened, and the inside of the reaction vessel 3110 is returned to atmospheric pressure. Thereafter, the conductive substrate 3112 is taken out from the reaction vessel 3110.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not restrict | limited at all by these.
<Reference photoconductor preparation example>
The lower charge injection blocking layer and the photoconductive layer are formed on the cylindrical substrate under the conditions shown in Table 1 using a plasma CVD apparatus using a high-frequency power source in the RF band as shown in FIG. A photoconductor (hereinafter also referred to as a reference photoconductor) was produced. As the cylindrical substrate, a cylindrical aluminum conductive substrate having a mirror finish with a diameter of 84 mm, a length of 381 mm, and a thickness of 3 mm was used.

<Electrophotographic photoconductor preparation example 1>
As shown in Table 2, an electrophotographic photoreceptor preparation example 1 was prepared in the same manner as the reference photoreceptor, except that a surface layer having a thickness of 0.4 μm was formed on the reference photoreceptor.

In the electrophotographic photosensitive member produced in the electrophotographic photosensitive member production example 1, the sum of the atomic density of silicon atoms in the surface layer and / or the atomic density of carbon atoms (hereinafter also referred to as Si + C atomic density) by the following method The ratio of the number of carbon atoms to the sum of the number of silicon atoms and the number of carbon atoms (hereinafter also referred to as C / (Si + C)) was determined. As a result, the Si + C atom density was 6.60 × 10 ²² atoms / cm ³ and C / (Si + C) was 0.60.

(Measurement of Si + C atom density, C / (Si + C))
First, a reference sample was prepared by cutting out a central portion in the longitudinal direction in an arbitrary circumferential direction of the reference photoconductor with a 15 mm square.
Next, each electrophotographic photosensitive member produced in the electrophotographic photosensitive member production example 1 was cut out in the same manner to produce a measurement sample.
The reference sample and the measurement sample were measured by spectroscopic ellipsometry (manufactured by JA Woollam: high-speed spectroscopic ellipsometry M-2000) to determine the layer thickness of the surface layer.

Specific measurement conditions of spectroscopic ellipsometry are incident angles: 60 °, 65 °, 70 °, measurement wavelengths: 195 nm to 700 nm, and beam diameter: 1 mm × 2 mm.
First, the relationship between the wavelength, the amplitude ratio Ψ, and the phase difference Δ was determined for each reference angle of the reference sample by spectroscopic ellipsometry.
Next, using the measurement result of the reference sample as a reference, the relationship between the wavelength, the amplitude ratio Ψ, and the phase difference Δ was obtained at each incident angle by spectroscopic ellipsometry in the same manner as the reference sample.

Further, a layer structure having a roughness layer in which a surface layer and an air layer coexist on the outermost surface is formed as a calculation model by sequentially forming a charge injection blocking layer, a photoconductive layer, and a surface layer. Then, the volume ratio between the surface layer and the air layer in the roughness layer was changed by analysis software, and the relationship between the wavelength at each incident angle, the amplitude ratio Ψ, and the phase difference Δ was obtained by calculation. Then, the mean square of “the relationship between the wavelength and the amplitude ratio Ψ and the phase difference Δ obtained by the above calculation” and “the relationship between the wavelength and the amplitude ratio Ψ and the phase difference Δ obtained by measuring the measurement sample” at each incident angle. The calculation model when the error was minimized was selected. The film thickness of the surface layer was calculated using the selected calculation model, and the obtained value was taken as the film thickness of the surface layer.
The analysis software is J.I. A. Woolase WVASE32 was used. Further, the volume ratio of the surface layer to the air layer in the roughness layer was calculated by changing the ratio of the air layer in the roughness layer by 1 from 10: 0 to 1: 9 in the surface layer: air layer. .
In the a-Si photosensitive member for positive charging produced under each film forming condition of this example,
Relationship between wavelength and amplitude ratio Ψ and phase difference Δ obtained by calculation when the volume ratio of the surface layer to the air layer in the roughness layer is 8: 2 and wavelength and amplitude ratio Ψ and phase difference obtained by measurement The mean square error of the Δ relationship was minimized.

  After the measurement by spectroscopic ellipsometry was completed, the number of silicon atoms and carbon atoms in the surface layer in the RBS measurement area of the measurement sample was measured by RBS (Rutherford backscattering method). As a measuring device, a back scattering measuring device AN-2500 manufactured by Nissin High Voltage Co., Ltd. was used. C / (Si + C) was determined from the measured number of silicon atoms and carbon atoms. Next, the Si + C atom density was calculated | required using the film thickness of the surface layer calculated | required by spectroscopic ellipsometry with respect to the silicon atom and carbon atom which were calculated | required from the measurement area of RBS.

Specific measurement conditions for RBS and HFS are incident ion: 4He ⁺ , incident energy: 2.3 MeV, incident angle: 75 °, sample current: 35 nA, and incident beam length: 1 mm.
The RBS detector was measured with a scattering angle of 160 ° and an aperture diameter of 8 mm, and the HFS detector was measured with a recoil angle of 30 ° and an aperture diameter of 8 mm + Slit.

<Example 1>
An a-Si photoreceptor was produced in the same manner as in the electrophotographic photoreceptor preparation example 1 except that it was produced under the conditions shown in Table 3 and Table 4. In addition, regarding the preparation conditions of the surface layer, the conditions other than the layer thickness are the same as those of the electrophotographic photoreceptor preparation example 1.

The electrophotographic photosensitive member produced in Example 1 was installed in the electrophotographic apparatus shown in FIG. 2 set to the process conditions shown in Table 5. Then, the absorption ratio, charging ability and gradation are evaluated by the following methods, and the results are shown in Table 8.
The absorption ratio is a value calculated by the following calculation formula.
Absorption ratio = light quantity 2 / light quantity 1
Amount of light 1: Amount of pre-exposure absorbed by the electrophotographic photosensitive member Amount of light 2: Amount of pre-exposure absorbed by all layers existing on the free surface side of the photoconductive layer

  The electrophotographic apparatus used in Example 1 is a modified machine of a digital electrophotographic apparatus “iRA-8105” (trade name) manufactured by Canon Inc. This modified machine is provided with a motor (not shown) for rotating the electrophotographic photosensitive member in order to change the process speed (hereinafter also referred to as PS). A high voltage power source (not shown) is connected to the wire and grid of the charging means so that the surface potential of the electrophotographic photosensitive member can be adjusted.

Further, a shielding member was installed so that the pre-exposure irradiated from the pre-exposure means to the electrophotographic photosensitive member could not be irradiated in a range of ± 10 mm around the longitudinal center position of the electrophotographic photosensitive member. Then, a light source (halogen lamp) and a spectroscope (manufactured by JASCO Corporation: CT-25C type diffraction grating) are used so that light can be irradiated in a range where the pre-exposure light irradiated from the pre-exposure means is shielded. Spectroscope) was installed.
The pre-exposure irradiated from the spectral light source to the surface of the electrophotographic photosensitive member was adjusted such that the irradiation energy to the electrophotographic photosensitive member was 2 μJ regardless of the wavelength of the pre-exposure and PS. In Example 1, PS was set to 700 mm / second. As a light source for image exposure, a semiconductor laser having an oscillation wavelength of 658 nm was used.

<Comparative Example 1>
An a-Si photoreceptor was produced in the same manner as in Example 1 except that the upper charge injection blocking layer and the surface layer were formed under the conditions shown in Table 6. The film formation conditions of Table 6 The thickness of each layer of No. 4 is the film formation condition No. Same as 4.

  The electrophotographic photosensitive member produced in Comparative Example 1 was installed in the electrophotographic apparatus shown in FIG. 2 set to the process conditions shown in Table 7. And it evaluated similarly to Example 1. FIG. The results at this time are shown in Table 8.

(Calculation method of absorption ratio with respect to wavelength of light of pre-exposure)
First, the reflectivity of the electrophotographic photoreceptor produced in the reference photoreceptor production example was measured.
The measurement positions are 6 points in total, which are positions rotated every 60 ° from an arbitrary circumferential direction from the reference position with respect to the center in the longitudinal direction of the electrophotographic photoreceptor in any circumferential direction of the electrophotographic photoreceptor. Moreover, the measurement method irradiates the surface of the electrophotographic photosensitive member perpendicularly with a spot diameter of 2 mm, and spectroscopic measurement of reflected light was performed using a spectrometer (manufactured by Otsuka Electronics: MCPD-2000).
From the result of spectroscopic measurement of reflected light measured at six measurement points, the reflectance of the wavelength of the pre-exposure light at each measurement position was obtained, and the average value a (%) was calculated. This average value a was taken as the reflectance of the reference photoreceptor.

Next, the light absorption in all layers on the free surface side with respect to the wavelength of the pre-exposure light was measured.
First, the reference photoconductor was mounted on a modified machine of the above-mentioned digital electrophotographic apparatus “iRA-8105” (trade name) manufactured by Canon Inc. At that time, the developing device was removed, and a surface potential meter (Model 555P-4 manufactured by TREK) was installed so that the surface potential of the electrophotographic photosensitive member at the center position in the longitudinal direction of the electrophotographic photosensitive member can be measured. Further, the shielding member was removed from the pre-exposure means, and the supply of current to the semiconductor laser for image exposure was stopped so as not to emit light. Further, the pre-exposure irradiated from a light source (halogen lamp) not shown and a spectroscope (manufactured by JASCO Corporation: CT-25C type diffraction grating spectroscope) can be irradiated to the position where the image exposure is irradiated at 2 μJ. Was installed.

  Then, a high-voltage power supply is connected to the charger wire and grid with the halogen lamp turned off, the grid potential is set to -700 V, and the current supplied to the charger wire is adjusted to adjust the surface potential of the electrophotographic photosensitive member. Was set to −500V. At this time, the current I (μA) flowing from the wire of the charger to the electrophotographic photosensitive member was measured. Further, the pre-exposure when the surface potential of the electrophotographic photosensitive member at the position of the developing device is adjusted to -150 V by turning on the halogen lamp and irradiating pre-exposure light in a state of being charged under the previously set charging conditions. The irradiation energy b (μJ) of was measured.

Of the irradiation energy b of the light that changes the surface potential from −500 V to −150 V, it can be considered that light other than that detected as reflected light from the reference photoconductor enters the reference photoconductor and is absorbed. Therefore, the pre-exposure irradiation energy E1 (μJ) absorbed by the reference photosensitive member at this time is b × (1−a / 100).
Next, the reflectance c at the wavelength of the pre-exposure light in the produced electrophotographic photosensitive member was determined in the same manner as the reference photosensitive member.

After obtaining the reflectance, the surface potential of the produced electrophotographic photoreceptor was measured in the same manner as the reference photoreceptor. At that time, the current flowing from the charger wire to the electrophotographic photosensitive member is adjusted to I (μA), and the amount of charge applied to the surface between the produced electrophotographic photosensitive member and the reference photosensitive member is made constant. The surface potential V ₁ (V) of the electrophotographic photosensitive member was measured. Then, in order to align the change in the surface charge of the electrophotographic photosensitive member when the pre-exposure light is radiated to 350 V by irradiating the pre-exposure light on the reference photosensitive member, the prepared electrophotographic photosensitive member is irradiated with image exposure light, 150 × _V 1/500 irradiation energy of exposure before when the (V) d a (.mu.J) was measured.

Among irradiation energy d of image exposure to the surface potential from V _{1 (V)} to _{150 × V 1/500 (V} ), light other than that are detected as reflected light from the electrophotographic photosensitive member thus prepared was prepared electronic It can be considered that it has been absorbed into the photographic photosensitive body. Therefore, the pre-exposure irradiation energy E2 (μJ) absorbed by the electrophotographic photosensitive member produced at this time is d × (1−c / 100).

Based on E1 and E2 calculated by the above method, among the pre-exposure light amount irradiated to the electrophotographic photosensitive member, all of the light exposure layers on the free surface side with respect to the pre-exposure light amount absorbed by the electrophotographic photosensitive member. The ratio (E2-E1) / E2 of the amount of pre-exposure light absorbed by the layer was calculated.
The irradiation energy E2 (μJ) produced a surface charge equal to the amount of decrease in surface charge when the surface potential was changed by 350 V by irradiating the reference photoconductor with pre-exposure light of E1 (μJ). This is the energy required to reduce the electrophotographic photosensitive member. From this, (E2-E1) / E2 makes it possible to calculate the amount of image exposure absorbed by a layer that is substantially on the free surface side of the photoconductive layer.

(Evaluation of charging ability)
For the evaluation method of the charging ability, a modified machine of the above-mentioned Canon Inc. digital electrophotographic apparatus “iRA-8105” (trade name) installed in an environment of a temperature of 25 ° C. and a relative humidity of 50% was used.
The produced electrophotographic photosensitive member was set in the electrophotographic apparatus, pre-exposure was adjusted to a predetermined wavelength, and the developing device was removed. Then, a surface potential meter (Model 555P-4 manufactured by TREK) was installed so that the surface potential of the electrophotographic photosensitive member at the center position in the longitudinal direction of the electrophotographic photosensitive member can be measured. Next, the wavelength of pre-exposure irradiated to the electrophotographic photosensitive member from the spectral light source was set to 630 nm. Then, with the image exposure cut off, the surface potential of the electrophotographic photosensitive member when the grid of the charging device is set to −700 V and the current flowing from the charging device wire to the electrophotographic photosensitive member is set to −300 μA is measured. The charging potential with respect to the wavelength of exposure was determined.

  The pre-exposure wavelength irradiated from the spectral light source to the electrophotographic photosensitive member is changed from 630 nm to 560 nm every 1 nm, the conditions of the wire and grid of the charger are fixed, and similarly, charging for each pre-exposure wavelength is performed. The potential was determined. Then, the maximum value of the surface potential when the pre-exposure wavelength was changed was calculated from the surface potential of the electrophotographic photosensitive member obtained when the pre-exposure wavelength was changed. Further, the ratio of “charging potential at each wavelength of pre-exposure” to “maximum value of surface potential” was calculated.

(Evaluation of gradation)
For the evaluation of gradation, a modified machine of the above-mentioned digital electrophotographic apparatus “iRA-8105” (trade name) manufactured by Canon Inc. was used.
First, a high voltage power source was connected to the wire and grid of the charger. Then, the pre-exposure is adjusted to a predetermined wavelength, the grid potential is set to −700 V with the image exposure turned off, and the current supplied to the wire of the charger is adjusted to adjust the surface potential of the electrophotographic photosensitive member to − The voltage was set to 500V.

Next, the image exposure light was irradiated in the state charged under the previously set charging conditions, and the irradiation energy was adjusted, so that the potential at the developing unit position was set to -150V.
Then, an area gradation dot screen is used at a line density of 45 degrees 170 lpi (170 lines per inch) by image exposure light, and the entire gradation range is determined by area gradation (that is, area gradation of a dot portion where image exposure is performed). The gradation data was distributed evenly in 17 steps. At this time, the darkest gradation was set to 17, the thinnest gradation was set to 0, and a number was assigned to each gradation to obtain a gradation step.

The prepared electrophotographic photosensitive member was installed in the modified electrophotographic apparatus, and output to A3 paper using the gradation data using the text mode. At this time, in an environment of a temperature of 22 ° C. and a relative humidity of 50%, the photoconductor heater was turned on, and an image was output under the condition that the surface temperature of the electrophotographic photoconductor was kept at about 40 ° C.
The image density of the obtained image was measured with a reflection densitometer (manufactured by X-Rite Inc: 504 spectral densitometer) for each gradation. In the reflection density measurement, three images were output for each gradation, and the average value of the densities was used as the evaluation value.

  The correlation coefficient between the evaluation value obtained in this way and the gradation stage is calculated, and from the correlation coefficient = 1.00 when the gradation expression in which the reflection density of each gradation changes completely linearly is obtained. The difference of was calculated. The process condition No. The ratio of the difference obtained from the correlation coefficient calculated from the image output under each process condition to the difference obtained from the correlation coefficient calculated from the image output in step 3 was evaluated as a gradation index. . In this evaluation, the smaller the numerical value, the better the gradation, indicating that the gradation expression is linear.

A. Process condition no. The correlation coefficient calculated from the image output under each process condition with respect to the difference from the correlation coefficient calculated from the correlation coefficient calculated from the image output in step 3 = 1.00 = difference from 1.00 Ratio is 1.80 or less.
B Process condition No. The correlation coefficient calculated from the image output under each process condition with respect to the difference from the correlation coefficient calculated from the correlation coefficient calculated from the image output in step 3 = 1.00 = difference from 1.00 The ratio is greater than 1.80.
The absorption ratio, charging ability and gradation property evaluated in Example 1 and Comparative Example 1 were comprehensively evaluated by the following methods. The results are shown in Table 8.

(Comprehensive evaluation)
Regarding the evaluation result of charging ability, A is 0.975 or more and 1.000 or less, and B is lower than 0.975.
As a comprehensive evaluation, each evaluation result of charging ability and gradation was evaluated as shown below.
A: Each evaluation result of charging ability and gradation is A. B. Evaluation result of charging ability is A and evaluation result of gradation is B. C ... Evaluation result of charging ability is B. Overall evaluation In B, it was judged that the effect of the present invention was obtained at B or higher.

From the results in Table 8, the pre-exposure of 0.975 or more and 1.000 or less with respect to the maximum value of the charging potential obtained when the wavelength of the pre-exposure light is changed under the predetermined electrophotographic process conditions. The effect of the present invention was confirmed by selecting the wavelength of light. That is, even when an electrophotographic apparatus having a relatively fast PS is used, it is possible to suppress a reduction in gradation while maximizing the charging potential of the electrophotographic photosensitive member. It was confirmed that quality image quality can be output.
Furthermore, the ratio of the pre-exposure light amount absorbed by all the layers on the free surface side of the photoconductive layer to the pre-exposure light amount absorbed by the electrophotographic photosensitive member is 25% or more and 55% or less, In addition, it was confirmed that the gradation was prevented from being lowered and that a higher quality image could be output.

<Example 2, comparative example 2>
Using the electrophotographic apparatus shown in FIGS. 2A and 2B, the absorption conditions, charging ability and gradation were evaluated in the same manner as in Example 1 with the process conditions shown in Table 9. The results at this time are shown in Table 10. 2A and 2B was mounted with the electrophotographic photosensitive member of film formation condition No. 4 produced in Example 1. FIG. FIG. 2B is the same as the electrophotographic apparatus of FIG. 2A except that the pre-exposure unit is installed between the transfer unit and the cleaning unit.

From the results shown in Table 10, when the pre-exposure unit is moved between the cleaning unit and the charging unit between the transfer unit and the cleaning unit, the charging ability is 0.964 V to 0.975 V even when the wavelength of the pre-exposure light is 623 nm. It was confirmed that it changed to. That is, by moving the pre-exposure means, the wavelength of the pre-exposure light that is 0.975 or more and 1.000 or less with respect to the maximum value of the charging potential obtained when the wavelength of the pre-exposure light is changed. It was confirmed that the range expanded.
Therefore, by moving the pre-exposure unit between the cleaning unit and the charging unit between the transfer unit and the cleaning unit, the wavelength range of the pre-exposure light that can be used in the present invention is expanded, and the pre-exposure light It was confirmed that the selectivity of the wavelength was improved.

This is because the time from the pre-exposure means to the charging means is lengthened, so that when the pre-exposure is applied to the surface of the electrophotographic photosensitive member, the photocarriers generated in the photoconductive layer and the free surface layer are regenerated. This is presumably because the number of photocarriers remaining in the layer has decreased due to bonding.
Further, the pre-exposure means is also cleaned with respect to the maximum value of the charging potential obtained when the wavelength of the pre-exposure light is changed because the photocarriers remaining in the photoconductive layer and the free surface side layer are reduced. 5% improvement was confirmed by moving between the transfer means and the cleaning means from between the charging means and the charging means.

1001, 2001 ... Electrophotographic photoreceptors 1002, 2002 ... Primary charger 1003, 2003 ... ... Image exposure 1004a ..... ········································································································· ITB
1007, 2007 ... Magnet roller 1008, 2008 ... ... Cleaning blade 1009, 2009 ... ... First transfer member 1010 ... ..... 2nd transfer member 1011 ... ITB cleaner 1012, 2012 ... Transport means 1013, 2013 ... Recording materials 1014, 2014 ... ……………… Pre-exposure 2004 …………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………….
2011 ‥‥‥‥‥‥‥‥‥‥‥‥ ETB cleaner 3100 ‥‥‥‥‥‥‥‥‥‥‥‥ deposition apparatus 3200 ‥‥‥‥‥‥‥‥‥‥‥‥ gas supply device 4000 ‥‥‥ ················································································································ ... Lower charge injection blocking layer 4003, 4103, 4203 ... Photoconductive layer 4004 ..... Intermediate layer 4104 ..... Upper charge injection blocking layer 4005 4105 4205 ... surface layer

Claims (4)

An electrophotographic photosensitive member in which a photoconductive layer and a surface layer are sequentially formed on a conductive substrate; pre-exposure means for irradiating the electrophotographic photosensitive member with pre-exposure light; and charging the electrophotographic photosensitive member. A main charging means for carrying out the process, a latent image forming means for forming an electrostatic latent image on the charging surface of the electrophotographic photosensitive member, a developing means for developing the electrostatic latent image as a toner image, and transferring the toner image. In an electrophotographic apparatus having transfer means,
The pre-exposure means;
Pre-exposure light in which the charging ability is 0.975 or more and 1.000 or less when the maximum value of charging ability of the electrophotographic photosensitive member that changes when the wavelength of the pre-exposure light is changed is 1.000. An electrophotographic apparatus having the following wavelength:   The ratio of the amount of pre-exposure light absorbed by all layers on the free surface side of the photoconductive layer to the amount of pre-exposure light absorbed by the electrophotographic photosensitive member is 25% or more. The electrophotographic apparatus according to claim 1, wherein the electrophotographic apparatus has a wavelength of pre-exposure light that is 55% or less. A cleaning unit on the downstream side of the transfer unit and the upstream side of the main charging unit with respect to the rotation direction of the electrophotographic photosensitive member;
3. The electrophotographic apparatus according to claim 1, wherein the pre-exposure unit is positioned upstream of the cleaning unit with respect to a rotation direction of the electrophotographic photosensitive member. An electrophotographic photosensitive member in which a photoconductive layer and a surface layer are sequentially formed on a conductive substrate; pre-exposure means for irradiating the electrophotographic photosensitive member with pre-exposure light; and charging the electrophotographic photosensitive member. A main charging means for carrying out the process, a latent image forming means for forming an electrostatic latent image on the charging surface of the electrophotographic photosensitive member, a developing means for developing the electrostatic latent image as a toner image, and transferring the toner image. A method for setting an electrophotographic apparatus having transfer means,
As pre-exposure light of the pre-exposure means,
Pre-exposure light in which the charging ability is 0.975 or more and 1.000 or less when the maximum value of charging ability of the electrophotographic photosensitive member that changes when the wavelength of the pre-exposure light is changed is 1.000. A method for designing an electrophotographic apparatus, characterized in that the wavelength is selected.

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