JP5593617B2 - Image carrier, image forming method, image forming apparatus, and process cartridge - Google Patents

Description

  The present invention relates to an image forming method to which an electrophotographic method is applied, an image carrier used in the image forming apparatus, an image forming method using the image carrier, an image forming apparatus, and a process cartridge.

  In general, the “electrophotographic method” uses a photoconductive image carrier (referred to as a photoconductor). First, the photoconductor is charged in a dark place (for example, charged by corona discharge) and then exposed to light for image exposure. , By selectively dissipating the electric charge of only the exposed portion to form an electrostatic latent image, and the latent image portion is composed of a detecting fine particle comprising a colorant such as a dye or a pigment and a binder such as a polymer substance ( This is one of image forming methods in which a toner is developed and visualized to form an image.

In such an electrophotographic method, as a basic characteristic required for a photoconductor as an image carrier,
・ It can be charged to an appropriate potential in the dark.
・ Low charge dissipation in the dark,
・ Charge can be quickly dissipated by light irradiation,
Etc.

  Conventionally, as a photoconductor used in an electrophotographic method, an inorganic photoconductive material such as zinc oxide or cadmium sulfide is contained in a resin in which a photosensitive layer mainly composed of selenium or a selenium alloy is provided on a conductive support. In general, those dispersed in water, those using poly-N-vinylcarbazole and organic photoconductive materials such as trinitrofluorenone or azo pigments, and those using amorphous silicon-based materials are generally known. In recent years, organic electrophotographic photoreceptors have been widely used due to low cost, high degree of freedom in designing photoreceptors, low pollution, and the like.

  For organic electrophotographic photoreceptors, photoconductive resin type represented by polyvinylcarbazole (PVK), charge transfer complex type represented by PVK-TNF (2,4,7-trinitrofluorenone), phthalocyanine-resin Are known, such as a pigment dispersion type, a function separation type photoreceptor using a combination of a charge generation material and a charge transport material, and the function separation type photoreceptor is attracting attention.

  The mechanism of electrostatic latent image formation in this function-separated type photoreceptor is that when the photoreceptor is charged and then irradiated with light, the light passes through the transparent charge transport layer and is absorbed by the charge generation material in the charge generation layer. The charge generating material that has absorbed the light generates charge carriers, which are injected into the charge transport layer, move in the charge transport layer according to the electric field generated by the charging, and neutralize the charge on the surface of the photoreceptor. By doing so, an electrostatic latent image is formed. In the functionally separated type photoreceptor, it is known to use a combination of a charge transport material having absorption mainly in the ultraviolet region and a charge generation material having absorption mainly in the visible region, and the above basic characteristics are sufficiently obtained. What you meet is obtained.

In recent years, as the speed and miniaturization of the electrophotographic process progresses, in addition to the above characteristics, there is a strong demand for reliability and high durability that can maintain high image quality even when used repeatedly for a long time. ing.
The photoreceptor is subjected to various mechanical and chemical loads in the electrophotographic process. Of these, the chemical load is greatly influenced by ozone, nitrogen oxides, etc. generated from the charged portion in the electrophotographic process. These ozone, nitrogen oxides and the like are generated at the charged portion and adsorbed on the surface of the photoreceptor to cause chemical changes. Ozone generated from the charging step oxidizes the binder resin and charge transport material that form the photoreceptor. And the molecular chain of binder resin is cut | disconnected, and organic acids, such as carboxylic acid, are produced | generated. Similarly, the generated discharge product such as nitrogen oxide becomes a substance having electrical conductivity by binding or reacting with water (water molecules) in the air. When this substance and the above-mentioned organic acid are adsorbed on the photoconductor, the resistance near the surface of the photoconductor is lowered, and the electrostatic latent image formed on the photoconductor is destroyed. As a result, a so-called image-flow toner image is formed on the photoconductor subjected to the development process. In addition, the discharge product adsorbed on the photoconductor generally causes an increase in the coefficient of friction of the photoconductor surface. As a result, for example, the mechanical load at the contact portion of the cleaning blade to the photoconductor increases, and further, as described above. Photoreceptor wear is promoted by the molecular chain scission of the binder resin forming the photoreceptor. Moreover, generation | occurrence | production of these ozone, nitrogen oxides, etc. also becomes a problem also from an environmental side.

In general, a corona charging method or a contact charging method has been used as a charging method in electrophotography.
Corona charging methods include a corotron method and a scorotron method with a grid, and a direct current or a direct current voltage superimposed on an alternating current is applied to a tungsten or nickel charge wire stretched in the center of a housing shielded by a metal plate. In this method, corona discharge is caused to charge the photosensitive member. However, in this method, ozone, nitrogen oxide, or the like is generated in order to apply a high voltage to the charge wire. This product is known to adversely affect not only environmental aspects but also the photoreceptor and durability and image characteristics as described above.

In recent years, instead of this method, a contact charging method has been put into practical use for the purpose of low ozone and low power. In the contact charging method, a direct current voltage or a direct current voltage superimposed on an alternating current is applied to a charging member having a resistance of about 10 ² to 10 ¹⁰ Ω · cm, and the photosensitive member is pressed and brought into contact with the photosensitive member to give an electric charge. Is the method. Since this charging method is performed by discharging from the charging member to the member to be charged in accordance with Paschen's law, charging is started by applying a voltage equal to or higher than a certain threshold voltage. In this contact charging method, the voltage applied to the charging member is lower than that in the corona charging method, but a small amount of ozone and nitrogen oxides are generated due to discharge.

  For this reason, as a new charging method, a charging method (for example, Patent Document 1 (Japanese Patent Laid-Open No. 06-003921)) by directly injecting charges into the photoreceptor is disclosed. This charging method is a method in which a low-resistance charge injection layer is provided on the surface of a photoconductor, a voltage is applied to a contact conductive member such as a charging roller, a charging brush, a charging magnetic brush, etc., and charging is performed by contact with the charge. . Since this charging method does not use the discharge phenomenon, the voltage required for charging is only the desired surface potential of the photoreceptor. Therefore, compared with the conventional contact charging method, the generation amount of ozone and nitrogen oxide is very small, and this is a low power charging method. The charge injection layer provided on the photoconductor for performing these charge injection charges has a metal oxide such as tin oxide dispersed in the resin to lower the surface resistance of the photoconductor. However, the surface resistance of such a photoreceptor varies greatly depending on the environment (temperature, humidity) used, and stable charging cannot be performed. Therefore, as a method for controlling the in-machine environment, installation of a heater or the like in the apparatus is conceivable. However, when such a heater is installed, the power consumption of the entire machine increases.

  Next, a charging method (for example, Patent Document 2 (Japanese Patent Laid-Open No. Hei 8-76559)) is disclosed in which the photosensitive member is irradiated with light and the generated electric charge is transferred to the surface of the photosensitive member by an external electric field. In this method, ozone, nitrogen oxides, etc. are not generated compared to charge injection charging, and the characteristics change less depending on the use environment (temperature, humidity) with low power.

  In the charging method disclosed in Patent Document 3 (Japanese Patent Laid-Open No. 8-76559) and Patent Document 4 (Japanese Patent Laid-Open No. 9-26681), a charge generating layer and a charge transport layer are formed on a conductive support as a photosensitive member. An existing electrophotographic photoreceptor such as a laminated electrophotographic photoreceptor having a structure in which layers are sequentially laminated and a single-layer electrophotographic photoreceptor having a single photosensitive layer provided on a conductive support is used. In this photoreceptor, since the layer that generates charge during charging and the layer that generates charge during latent image formation are the same, the time from charge generation during charging to charge generation during latent image formation is limited, It becomes impossible to cope with small diameter and high speed.

  In the electrophotographic photosensitive member disclosed in Patent Document 5 (Patent No. 3895514), a layer that generates charge when charged, a charge transport layer, a layer that generates charge when forming a latent image, and a surface edge portion on a conductive support. It is the structure which has the provided electrode. With the photoconductor having this configuration, the above problem is solved. When the photosensitive member having this configuration is charged, a voltage is applied to the surface end electrode to form an electric field, and the charge is moved. In this method, in order to perform charging uniformly, it is necessary to reduce the resistance of the outermost layer. However, when such a low resistance layer is provided, the latent image formed on the surface of the photoreceptor is expanded, and the fine line reproducibility and fine dot reproducibility are lowered.

Therefore, in order to solve these problems, in the electrophotographic photosensitive member disclosed in Patent Document 6 (Patent No. 3566275) previously proposed by the present inventors, a charge is formed on a conductive support when a latent image is formed. By providing a generation layer, a charge transport layer, and a layer for generating a charge during charging, and further limiting the charge generation material of each charge generation layer, the image was hardly deteriorated and an efficient charging property was achieved.
In an electrophotographic process using such a photoreceptor,
(1) Charging,
(2) Exposure (writing),
(3) toner development,
(4) Toner transfer,
(5) Toner fixing,
Image formation is performed in the steps such as these.

Further, in Patent Document 7 (Japanese Patent Laid-Open No. 2007-178816) previously proposed by the present inventors, an image formation in which the charging process is omitted and the latent image forming process is simplified in the above-described electrophotographic process. A method is disclosed. In this method, a bias is applied from the surface of the photosensitive member by a transparent bias applying member, and at the same time, optical writing is performed to form a latent image. This eliminates the charging step that accompanies discharge that generates products such as ozone and nitrogen oxides (NOx).
However, in this method, since a bias is applied from the outside of the image carrier (photoreceptor) by a transparent bias applying member and optical writing is performed at the same time, a member for applying a bias from the outside is necessary. There is a problem that the size of the apparatus increases and the size of the apparatus increases. Also, when a bias is applied from the outside, if a foreign object (toner, developer, paper dust, etc.) is interposed between the image carrier and the external bias application member, the bias application to the image carrier becomes non-uniform. Problems such as density unevenness occur. In addition, the surface of the image carrier may be damaged.

  The present invention has been made to solve the above-described problems of the prior art, and eliminates a charging step that causes generation of ozone, nitrogen oxide (NOx), and the like, and forms an electrostatic latent image having a large potential contrast. It is an object of the present invention to provide an image carrier having a configuration capable of achieving the above, an image forming method using the image carrier, an image forming apparatus, and a process cartridge.

As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by adopting the following means to solve the problems, and the present invention has been achieved.
That is, the first solving means of the present invention is an image carrier used for image formation and on which an electrostatic latent image is formed. The image carrier is formed on at least a photosensitive layer on a conductive support. The upper electrode having a portion covering and not covering the photosensitive layer, and a protective layer are sequentially laminated, and the upper electrode is exposed to light from the image carrier surface side. A bias is applied, the bias to the upper electrode is stopped, and the upper electrode is floated or grounded to form a latent image (claim 1).

A second solving means of the present invention is an image carrier used for image formation and on which an electrostatic latent image is formed. The image carrier is formed on a conductive support, at least a photosensitive layer, a charge layer, It has a structure in which a holding layer, an upper electrode having a portion covering the charge holding layer and a portion not covered, and a protective layer are sequentially laminated, and at the time of light irradiation from the image carrier surface side , A bias is applied to the upper electrode, the bias to the upper electrode is stopped, and the upper electrode is floated or grounded to form a latent image. ).

A third solving means of the present invention is an image carrier used for image formation and on which an electrostatic latent image is formed. The image carrier is formed on a conductive support, at least a photosensitive layer, It has a structure in which an upper electrode formed in a stripe shape on a photosensitive layer and a protective layer are sequentially laminated, and a bias is applied to the upper electrode during light irradiation from the image carrier surface side , and the upper electrode The latent image is formed by stopping the bias to and the upper electrode being floated or grounded .

A fourth solution of the present invention is an image carrier that is used for image formation and forms an electrostatic latent image. The image carrier is formed on a conductive support, at least a photosensitive layer, a charge, It has a structure in which a holding layer, an upper electrode formed in a stripe shape on the charge holding layer, and a protective layer are sequentially laminated, and a bias is applied to the upper electrode when light is irradiated from the image carrier surface side. When applied , the bias to the upper electrode is stopped, and the upper electrode is floated or grounded, whereby a latent image is formed.

According to a fifth aspect of the present invention, there is provided an image carrier that is used for image formation and on which an electrostatic latent image is formed. The image carrier is formed on a conductive support, at least a photosensitive layer, It has a structure in which an upper electrode formed in a lattice shape on a photosensitive layer and a protective layer are sequentially laminated, and a bias is applied to the upper electrode during light irradiation from the image carrier surface side , and the upper electrode The latent image is formed by stopping the bias to and the upper electrode being floated or grounded (Claim 5).

A sixth solving means of the present invention is an image carrier used for image formation and on which an electrostatic latent image is formed. The image carrier is formed on a conductive support, at least a photosensitive layer, and a charge. It has a structure in which a holding layer, an upper electrode formed in a lattice shape on the charge holding layer, and a protective layer are sequentially stacked, and a bias is applied to the upper electrode when light is irradiated from the image carrier surface side. When applied , the bias to the upper electrode is stopped, and the upper electrode is floated or grounded , thereby forming a latent image (claim 6).

According to a seventh solving means of the present invention, in the image carrier of any one of the first to sixth solving means, the photosensitive layer has a single layer structure, and the photosensitive layer having the single layer structure has a charge generation function. And a charge transporting function (claim 7).
According to an eighth solving means of the present invention, in the image carrier of any one of the first to sixth solving means, the photosensitive layer has a laminated structure, and the photosensitive layer having the laminated structure has a charge generation function. And a charge transport layer having a charge transport function (claim 8).

According to a ninth solving means of the present invention, in the image carrier of any one of the first to eighth solving means, the protective layer is a film having a diamond-like carbon or an amorphous carbon structure. (Claim 9).
According to a tenth solving means of the present invention, in the image carrier of any one of the first to eighth solving means, the protective layer is a film in which a filler is dispersed in a resin. (Claim 10).

An eleventh solving means of the present invention is an image forming method, wherein the image carrier of any one of the first to tenth solving means is used, and the upper portion is irradiated with light from the image carrier surface side. A bias image is applied to the electrode, the bias to the upper electrode is stopped, and the upper electrode is floated or grounded to form a latent image (claim 11).

According to a twelfth solving means of the present invention, there is provided an image forming apparatus comprising the image carrier of any one of the first to tenth solving means, and the upper portion at the time of light irradiation from the image carrier surface side. A means for forming a latent image by applying a bias to an electrode, stopping the bias to the upper electrode, and bringing the upper electrode into a floating state or a grounded state is provided (claim 12). .
According to a thirteenth solution of the present invention, in the image forming apparatus of the twelfth solution, at least light is irradiated from the image carrier surface side and a bias is applied to the upper electrode during the light irradiation. The latent image forming unit having means for forming a latent image and developing the latent image on the image carrier by stopping the bias to the upper electrode and bringing the upper electrode into a floating state or a grounded state And a developing unit that visualizes the image and a transfer unit that transfers the developed image on the image carrier onto a transfer medium.

A fourteenth solving means of the present invention is a process cartridge, which contains an image carrier of any one of the first to tenth solving means, a latent image forming means, a developing means, a transferring means, a cleaning means, It comprises at least one of static eliminating means (claim 14).
The fifteenth solving means of the present invention is an image forming apparatus, wherein the process cartridge of the fourteenth solving means is detachably attached.

The image carrier according to the present invention is coated on a conductive support with at least a photosensitive layer (or a photosensitive layer and a charge holding layer) and a portion covering the photosensitive layer (or charge holding layer). An upper electrode having a portion that is not formed (specifically, an upper electrode that is formed in a random pattern, a striped pattern, or a lattice pattern, and that covers the surface of the photosensitive layer (or charge holding layer) with a predetermined pattern) ) And a protective layer (which covers the surface of the image carrier including the upper electrode) are sequentially laminated, and the upper electrode (protects the image carrier) during light irradiation from the image carrier surface side. A bias is applied to the electrode of a predetermined pattern provided in the layer, the bias to the upper electrode is stopped, and the upper electrode is floated or grounded to form a latent image. Because it is characterized by The conventional charging process (charging process for applying charge from the outside of the image bearing member by a charging means) that causes generation of ozone, nitrogen oxides, etc. can be eliminated, and it is small in size and has little potential unevenness even in long-term use. An image carrier capable of directly forming a latent image can be provided.
In addition, since the image carrier according to the present invention has a protective layer on the outermost surface, the protective layer can protect the upper electrode and make the surface of the image carrier uniform (flattened). In addition to being prevented from being damaged by mechanical hazards such as a part, a transfer part, and a cleaning part, it is possible to prevent image unevenness from occurring.

The image forming method according to the present invention uses the image carrier having the above-described configuration and effects, applies a bias to the upper electrode when light is irradiated from the image carrier surface side , and stops the bias to the upper electrode. In addition, since the upper electrode is floated or grounded , a latent image is formed, so that it is possible to eliminate the conventional charging process that causes generation of ozone, nitrogen oxides, etc. In addition, an image forming method that can directly form a latent image with little potential unevenness can be realized.

An image forming apparatus according to the present invention includes an image carrier having the above-described configuration and effects, and applies a bias to the upper electrode during light irradiation from the surface of the image carrier, and stops the bias to the upper electrode. In addition, since the latent image is formed by bringing the upper electrode into a floating state or a grounded state, the conventional charging process that causes generation of ozone, nitrogen oxides, etc. can be eliminated, and it is small and can be used for a long time. In addition, an image forming apparatus capable of directly forming a latent image with little potential unevenness can be realized.

Since the process cartridge according to the present invention incorporates the image carrier having the above-described configuration and effects, it is possible to eliminate a member for performing a conventional charging process, and it is small in size and has little potential unevenness even in long-term use. A process cartridge capable of directly forming a latent image can be realized.
In addition, the image forming apparatus equipped with the process cartridge is detachable, can form a latent image directly with little potential unevenness even in long-term use, and can be easily maintained and maintained. It becomes possible.

FIG. 2 is a configuration explanatory view of an image carrier showing an embodiment of the present invention, where (a) is a top view of a main part of the image carrier, and (b) is a cross-sectional view of a main part as viewed from the side of the image carrier. It is principal part sectional drawing of the image carrier which shows another embodiment of this invention. 4 is a configuration explanatory view of an image carrier showing another embodiment of the present invention, in which (a) is a top view of the main part of the image carrier, and (b) is a cross-sectional view of the main part viewed from the side of the image carrier. . It is principal part sectional drawing of the image carrier which shows another embodiment of this invention. 4 is a configuration explanatory view of an image carrier showing another embodiment of the present invention, in which (a) is a top view of the main part of the image carrier, and (b) is a cross-sectional view of the main part viewed from the side of the image carrier. . It is principal part sectional drawing of the image carrier which shows another embodiment of this invention. It is principal part sectional drawing of the image carrier which shows another embodiment of this invention. It is principal part sectional drawing of the image carrier which shows another embodiment of this invention. It is principal part sectional drawing of the image carrier which shows another embodiment of this invention. It is principal part sectional drawing of the image carrier which shows another embodiment of this invention. It is principal part sectional drawing of the image carrier which shows another embodiment of this invention. It is explanatory drawing which shows the electrostatic latent image formation mechanism of the image carrier of this invention. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention. FIG. 2 is a configuration explanatory diagram of a specific example of a plasma CVD apparatus used when forming a protective layer made of diamond-like carbon or amorphous carbon structure on the outermost surface of the image carrier of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The image carrier (photoreceptor) according to the present invention covers at least a photosensitive layer (or a photosensitive layer and a charge holding layer) and the photosensitive layer (or charge holding layer) on a conductive support. Upper electrode having a part and an uncovered part (specifically, it is formed in a random pattern or stripe or lattice form, and is formed so as to cover the surface of the photosensitive layer (or charge holding layer) with a predetermined pattern) And a protective layer covering the surface of the image carrier including the upper electrode, and the upper electrode (image carrier) is irradiated with light from the image carrier surface side . A bias is applied to the electrode of a predetermined pattern provided in the protective layer), the bias to the upper electrode is stopped, and the upper electrode is floated or grounded to form a latent image. The configuration is as follows.
In the present invention, the image carrier having such a structure is used, and when the light is irradiated from the image carrier surface side , a bias is applied to the upper electrode, the bias to the upper electrode is stopped, and the upper electrode is stopped. By using an image forming process that forms a latent image by setting the lens to a floating state or a grounded state, a conventional charging process that causes generation of ozone, nitrogen oxides, etc. An image forming method and an image forming apparatus in which the process around the image carrier for forming the electrostatic latent image is simplified by eliminating the charging step).

First, a configuration example of the image carrier of the present invention will be described.
1A and 1B are explanatory views of the structure of an image carrier according to an embodiment of the present invention, in which FIG. 1A is a top view of a main part of the image carrier, and FIG. The basic configuration example of the image carrier of the present invention is shown. This image carrier has a structure in which a photosensitive layer 2 and an upper electrode 3 are sequentially laminated on a conductive support 1. Further, in FIG. 1, the protective layer is not shown in order to show an example of the shape of the upper electrode 3, but the surface of the image carrier including the upper electrode 3 is covered with the protective layer 5 as shown in FIG. .
In the configuration example shown in FIG. 1, the upper electrode 3 is formed in an irregular (random) pattern so as to have a portion covering the photosensitive layer 2 and a portion not covering the photosensitive layer 2.

  FIG. 2 is a cross-sectional view of the main part of an image carrier showing another embodiment of the present invention. This image carrier is provided with a charge holding layer 4 in addition to the structure of FIG. It has a structure in which a photosensitive layer 2, a charge holding layer 4, and an upper electrode 3 are sequentially laminated on the body 1. Although the protective layer is not shown in FIG. 2, the surface of the image carrier including the upper electrode 3 is covered with a protective layer 5 as shown in FIG. The upper electrode 3 is formed in an irregular (random) pattern so as to have a portion covering the charge retention layer 4 and a portion not covering the same as in FIG.

FIGS. 3A and 3B are configuration explanatory views of an image carrier showing another embodiment of the present invention, in which FIG. 3A is a top view of the main part of the image carrier, and FIG. It is a figure and shows another example of composition of the image carrier of the present invention. This image carrier has a structure in which a photosensitive layer 2 and a striped upper electrode 3a are sequentially laminated on a conductive support 1. Further, in FIG. 3, the protective layer is not shown in order to show an example of the shape of the upper electrode 3a, but the surface of the image carrier including the upper electrode 3a is covered with the protective layer 5 as shown in FIG. .
In the configuration example shown in FIG. 3, the upper electrode 3 a is formed in a striped (regular striped) pattern so as to have a portion covering the photosensitive layer 2 and a portion not covering the photosensitive layer 2.

  FIG. 4 is a cross-sectional view of an essential part of an image carrier showing another embodiment of the present invention. This image carrier is provided with a charge holding layer 4 in addition to the structure of FIG. It has a structure in which a photosensitive layer 2, a charge holding layer 4, and a striped upper electrode 3 a are sequentially laminated on the body 1. Although the protective layer is not shown in FIG. 4, the surface of the image carrier including the striped upper electrode 3a is covered with the protective layer 5 as shown in FIG. The upper electrode 3a is formed in a striped (regular striped) pattern so as to have a portion covering the charge holding layer 4 and a portion not covering the same as in FIG. ing.

FIGS. 5A and 5B are configuration explanatory views of an image carrier showing another embodiment of the present invention, in which FIG. 5A is a top view of the main part of the image carrier, and FIG. It is a figure and shows another example of composition of the image carrier of the present invention. This image carrier has a structure in which a photosensitive layer 2 and a grid-like upper electrode 3 b are sequentially laminated on a conductive support 1. In FIG. 5, the protective layer is not shown in order to show an example of the shape of the upper electrode 3b. However, the surface of the image carrier including the grid-like upper electrode 3b is covered with the protective layer 5 as shown in FIG. Covered.
In the configuration example shown in FIG. 5, the upper electrode 3b is formed in a regular lattice pattern so as to have a portion covering the photosensitive layer 2 and a portion not covering.
Although not shown, the charge retention layer 4 may be provided between the photosensitive layer 2 and the lattice-shaped upper electrode 3b.

  FIG. 6 is a cross-sectional view of an essential part of an image carrier showing another embodiment of the present invention, in which a protective layer 5 is provided on the outermost surface of the image carrier having the structure shown in FIG. 1, FIG. 3 or FIG. Is shown. That is, the image carrier has a structure in which a photosensitive layer 2, an upper electrode (random, striped, or grid-like electrode) 3, and a protective layer 5 are sequentially laminated on a conductive support 1. The surface of the image carrier including the electrodes 3 is covered with a protective layer 5 and is uniformed (flattened). As described above, since the image carrier shown in FIG. 6 has the protective layer 5 on the outermost surface, the protective layer 5 can protect the upper electrode 3 and make the surface of the image carrier uniform (flattened). Further, it is possible to prevent the upper electrode 3 from being damaged by mechanical hazards such as a developing unit, a transfer unit, and a cleaning unit, and it is possible to prevent the occurrence of image unevenness.

  FIG. 7 is a cross-sectional view of an essential part of an image carrier showing another embodiment of the present invention, showing a state in which a protective layer 5 is provided on the outermost surface of the image carrier having the structure shown in FIG. 2 or FIG. Yes. That is, this image carrier has a structure in which a photosensitive layer 2, a charge retention layer 4, an upper electrode (random, striped, or grid-like electrode) 3, and a protective layer 5 are sequentially laminated on a conductive support 1. The surface of the image carrier including the upper electrode 3 is covered with the protective layer 5 and is made uniform (flattened). As described above, since the image carrier shown in FIG. 7 has the protective layer 5 on the outermost surface, the protective layer 5 can protect the upper electrode 3 and make the surface of the image carrier uniform (flattened). Further, it is possible to prevent the upper electrode 3 from being damaged by mechanical hazards such as a developing unit, a transfer unit, and a cleaning unit, and it is possible to prevent the occurrence of image unevenness.

In the image carrier shown in FIGS. 1 to 7, the photosensitive layer 2 has a single layer structure, and the photosensitive layer having the single layer structure has a charge generation function and a charge transport function.
The photosensitive layer 2 may have a laminated structure, and the photosensitive layer having a laminated structure includes a charge generation layer having a charge generation function and a charge transport layer having a charge transport function.

FIG. 8 is a cross-sectional view of an essential part of an image carrier showing another embodiment of the present invention, and shows a configuration example in which the photosensitive layer 2 has a laminated structure. In this image carrier, a photosensitive layer 2 composed of a charge transport layer 2a and a charge generation layer 2b is laminated on a conductive support 1, and an upper electrode (random, striped, or grid-like electrode) 3 is formed thereon. The protective layer 5 is sequentially laminated.
FIG. 9 is a cross-sectional view of an essential part of an image carrier showing another embodiment of the present invention, and shows a configuration example in which a charge holding layer 4 is provided on a photosensitive layer 2 having a laminated structure. In this image carrier, a photosensitive layer 2 composed of a charge transport layer 2a and a charge generation layer 2b is laminated on a conductive support 1, and a charge holding layer 4 and an upper electrode (random, striped or lattice) are formed thereon. And the protective layer 5 are sequentially stacked.

FIG. 10 is a cross-sectional view of an essential part of an image carrier showing still another embodiment of the present invention, and shows a configuration example in which the photosensitive layer 2 has a laminated structure opposite to that in FIG. In this image carrier, a photosensitive layer 2 including a charge generation layer 2b and a charge transport layer 2a is laminated on a conductive support 1, and an upper electrode (random, striped, or grid-like electrode) 3 is formed thereon. The protective layer 5 is sequentially laminated.
FIG. 11 is a cross-sectional view of an essential part of an image carrier showing another embodiment of the present invention, and shows a configuration example in which a charge holding layer 4 is provided on a photosensitive layer 2 having a laminated structure. In this image carrier, a photosensitive layer 2 composed of a charge generation layer 2b and a charge transport layer 2a is laminated on a conductive support 1, and a charge holding layer 4 and an upper electrode (random, striped or lattice) are formed thereon. And the protective layer 5 are sequentially stacked.

Next, FIG. 12 shows an image forming mechanism by the image carrier of the present invention.
As shown in FIG. 12A, light writing is performed by irradiating light from the surface of the image carrier while applying a positive bias to the upper electrode 3 of the image carrier. As shown in FIG. 12B, the photocarrier generated by the exposure is separated into holes (+ charges) and electrons (−charges), and the electrons are transferred to the image carrier according to the electric field formed by the upper electrode 3. On the surface side, holes move to the conductive support 1 side. Thereafter, as shown in FIG. 12C, when the bias application to the upper electrode 3 is stopped and the float state or the ground state is established, electrons remain in the portion of the photosensitive layer 2 that is not covered with the electrode 3, A latent image is formed. Thereafter, the electrostatic latent image is developed with toner, whereby a toner image is formed on the surface of the image carrier.
This is an example for explaining the image forming mechanism, and a negative bias can be applied to the upper electrode 3. In this case, the behavior of the photocarrier is reversed between holes (+ charge) and electrons (−charge).

Hereinafter, the structure of the image carrier according to the present invention will be described in more detail.
The image carrier of the present invention comprises, on a conductive support 1, at least a photosensitive layer 2 and an upper electrode (random or striped or stripped or coated with the photosensitive layer 2). The grid electrode 3) and the protective layer 5 may be sequentially stacked, and other layers may be arbitrarily combined.

<About conductive support>
Examples of the conductive support 1 include those having a volume resistance of 10 ¹⁰ Ω · cm or less, such as metals such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, tin oxide, indium oxide, etc. After vapor deposition or sputtering, film or cylindrical plastic, paper coated, or aluminum, aluminum alloy, nickel, stainless steel, etc. Pipes subjected to surface treatment such as cutting, super finishing and polishing can be used. Further, an endless nickel belt or an endless stainless belt disclosed in Patent Document 8 (Japanese Patent Laid-Open No. 52-36016) can also be used as the conductive support.
In addition, the conductive support dispersed in an appropriate 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. Can be mentioned. The binder resin used at the same time includes 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-vinylcarbazole, acrylic resin, silicone resin, epoxy resin, melamine Examples thereof include thermoplastic, thermosetting resins, and photocurable resins such as resins, urethane resins, phenol resins, and alkyd resins. Such a conductive layer can be provided by dispersing and applying 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, 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.

<About photosensitive layer>
Next, the photosensitive layer 2 will be described. The photosensitive layer 2 may have a single layer structure or a laminated structure.
In the case of a photosensitive layer having a single layer structure such as the image carrier shown in FIGS. 1 to 7, the photosensitive layer 2 is a layer having a charge generation function and a charge transport function at the same time. In the case of a photosensitive layer having a laminated structure such as the image carrier shown in FIGS. 8 to 11, the photosensitive layer 2 includes a charge generation layer 2b having a charge generation function and a charge transport layer 2a having a charge transport function. Composed.
Hereinafter, each of the photosensitive layer having a single layer structure and the photosensitive layer having a multilayer structure will be described.

<Photosensitive layer having a single layer structure>
The photosensitive layer 2 having a single layer structure is a layer having a charge generation function and a charge transport function at the same time. The photosensitive layer can be formed by dissolving or dispersing a charge generation material having a charge generation function, a charge transport material having a charge transport function, and a binder resin in an appropriate solvent, and applying and drying the solution. Moreover, antioxidant, a plasticizer, a leveling agent, etc. can also be added as needed. As the charge generation material, inorganic materials and organic materials can be used.

  Inorganic materials include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compounds, and amorphous silicon. In amorphous silicon, dangling bonds that are terminated with hydrogen atoms or halogen atoms, or those that are doped with boron atoms, phosphorus atoms, or the like are preferably used.

  On the other hand, a known material can be used as the organic material. 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.

Examples of the charge transport material include a hole transport material and an electron transport material.
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 diphenoquinone derivatives. These electron transport materials can be used alone or as a mixture of two or more.

  Examples of the hole transporting material include the electron donating materials shown below and are used favorably. As hole transport materials, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, benzidine derivatives, diarylmethane derivatives, triaryls Other known materials such as methane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, enamine derivatives, and the like can be given. These hole transport materials can be used alone or as a mixture of two or more.

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, 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, melamine resin, urethane resin, Examples thereof include thermoplastic or thermosetting resins such as phenol resins and alkyd resins.
Moreover, antioxidant, a plasticizer, and a leveling agent can also be added as needed.

  Examples of the method for producing the photosensitive layer include dip coating, spray coating, bead coating, and ring coating. These coating liquids include the above-mentioned inorganic or organic charge generating materials together with a binder resin, if necessary, tetrahydrofuran, dioxane, dioxolane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, cyclopentanone, anisole, xylene, methyl ethyl ketone. It can be formed by dispersing with a ball mill, attritor, sand mill, bead mill or the like using a solvent such as acetone, ethyl acetate, butyl acetate, etc., and applying the solution after diluting the dispersion appropriately.

The film thickness of the photosensitive layer is suitably about 5 to 50 μm, preferably about 10 to 35 μm.
The charge generation material contained in the photosensitive layer is preferably 1 to 30% by weight based on the total amount of the photosensitive layer, the binder resin contained in the photosensitive layer is 20 to 80% by weight, and the charge transport material is 10 to 70% by weight. Is used satisfactorily.

<Photosensitive layer with a laminated structure>
(About the charge generation layer)
The charge generation layer 2b is a layer mainly composed of a charge generation material having a charge generation function, and the above-described binder resin can be used in combination as necessary. As the charge generation substance, the above-described inorganic materials and organic materials can be used. Moreover, the above-mentioned plasticizer and leveling agent can be added if necessary.

As a method for forming the charge generation layer 2b, a vacuum thin film preparation method, a dip coating method from a solution dispersion system, a spray coating, a bead coating, a ring coating method, or the like can be used.
As the vacuum thin film manufacturing method, a vacuum deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method, a reactive sputtering method, a CVD method, or the like is used.
The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.

(About charge transport layer)
The charge transport layer 2a is a layer mainly composed of a charge transport material having a charge transport function and a binder resin. As the charge transport material, the above-described hole transport material and electron transport material can be used, and as the binder resin, the above-described binder resin can be used. Moreover, the above-mentioned antioxidant, a plasticizer, and a leveling agent can also be added as needed.
The charge transport layer 2a is preferably capable of transporting a bipolar charge. In this case, the hole transport material and the electron transport material are both contained in the binder resin.

As a method for forming the charge transport layer 2a, a dip coating method, a spray coating, a bead coating, a ring coating method or the like can be used.
The thickness of the charge transport layer is suitably about 5 to 50 μm, preferably about 10 to 35 μm.
The charge generation layer 2b and the charge transport layer 2a are stacked on the conductive support 1 in the order of the charge transport layer 2a and the charge generation layer 2b even if the charge generation layer 2b and the charge transport layer 2a are stacked in this order. It does not matter.

<About the upper electrode>
The upper electrode 3 in the image carrier of the present invention is a layer that forms an electric field with respect to the photosensitive layer 2 by applying a bias. The material of the upper electrode is not particularly limited as long as it is a conductive material. Platinum, gold, silver, nickel, chromium, copper, iron, tin, antimony, lead, tantalum, indium, aluminum, zinc, magnesium, etc., and these Alloys and conductive metal oxides such as indium and tin oxide, or inorganic and organic semiconductors whose conductivity has been improved by doping, such as silicon single crystal, polysilicon, amorphous silicon, germanium, graphite, polyacetylene, poly Examples include paraphenylene, polythiophene, polypyrrole, polyaniline, polythienylene vinylene, polyparaphenylene vinylene, a complex of polyethylene dioxythiophene and polystyrene sulfonic acid, and the like.

  As a method for forming the upper electrode 3, a conductive thin film formed using the above-mentioned materials as a raw material by a method such as vapor deposition or sputtering is applied to a predetermined pattern (random or striped) using a known photolithography method or a lift-off method. And a method of etching into a predetermined pattern (random, striped, grid, etc.) using a resist such as thermal transfer or ink jet on a metal foil such as aluminum or copper. . Alternatively, a predetermined pattern (random, striped, grid, etc.) may be patterned directly by inkjet using a conductive polymer solution or dispersion, or a conductive fine particle dispersion. A predetermined pattern (random, striped, grid, etc.) may be formed by laser ablation or the like. Furthermore, a method of patterning an ink containing a conductive polymer or conductive fine particles, a conductive paste, or the like into a predetermined pattern (random, striped, grid, etc.) by a printing method such as relief printing, intaglio printing, planographic printing, or screen printing is also used. be able to.

The upper electrode 3 of the image carrier of the present invention does not completely cover the surface of the photosensitive layer 2 (or the charge holding layer 4), but has a covered portion and an uncoated portion. The coverage of the part covered with respect to the whole surface area is about 5 to 80%, Preferably it is about 10 to 50%. The electrode shape of the covered portion may be an irregular (random) shape as shown in FIG. 1, but is preferably a stripe shape (regular stripe shape) as shown in FIG. Preferably, it has a regular lattice shape as shown in FIG. In the case of the striped electrode 3a, the distance between the electrodes is 5 μm to 100 μm, preferably 5 to 20 μm. The same applies to the grid-like electrode 3b, and the interelectrode distance between the parallel electrodes is 5 μm to 100 μm, preferably 5 to 20 μm. The thickness of these electrodes is 0.01 μm to 5.00 μm, preferably 0.02 to 0.50 μm.

  The bias application to the upper electrode 3 is performed at the edge of the image carrier (for example, both ends in the width direction in the case of an endless belt-shaped image carrier, and both ends in the axial direction in the case of a drum-shaped image carrier) A bias is supplied by pressing a conductive member such as a conductive roller or a conductive brush against the electrode.

<Regarding the charge retention layer>
The charge holding layer 4 provided on the photosensitive layer 2 of the image carrier having the structure shown in FIGS. 2, 4, 7, 9, and 11 efficiently holds charges when forming an electrostatic latent image. It is provided for the purpose. The charge retention layer 4 mentioned here preferably has no charge transport capability, but may have a lower charge transport capability than the photosensitive layer 2 and the charge transport layer 2a described above.
For the charge retention layer 4, the binder resin material of the photosensitive layer 2 described above can be used. Moreover, antioxidant, a plasticizer, and a leveling agent can also be added as needed.
The thickness of the charge retention layer 4 is suitably about 0.2 to 5.0 μm, preferably about 0.5 to 2.5 μm.

<About protective layer>
The protective layer 5 provided on the upper electrode 3 is provided for the purpose of protecting the upper electrode 3 and making the surface of the image carrier uniform (flattened). The protective layer 5 does not directly affect the electrostatic latent image formation. However, in the image carrier of the present invention, when the upper electrode 3 disappears due to a mechanical hazard such as a developing unit, a transfer unit, or a cleaning unit, a basic electrostatic latent image cannot be formed. As described above, since the upper electrode 3 on the photosensitive layer (or the charge retention layer) is a thin film, it is vulnerable to these mechanical hazards, and it is necessary to provide the protective layer 5 for practical use. is there. However, a protective layer is not provided at the end of the image carrier that applies a bias to the upper electrode 3.

As the protective layer 5, the same binder resin material as that of the charge retention layer 4 can be used. Preferably, a film using a three-dimensional cross-linked resin such as urethane resin or acrylic resin, a film in which a filler is dispersed in the resin, or a film having a diamond-like carbon or amorphous carbon structure is used.
In particular, a protective layer having a diamond-like carbon or amorphous carbon structure is preferable. The protective layer having a diamond-like carbon or amorphous carbon structure 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.
The protective layer having a diamond-like carbon or amorphous carbon structure is an additive element such as nitrogen, fluorine, boron, phosphorus, chlorine, bromine, iodine for resistance control, light transmission control, mechanical property control, etc. May be contained.

When producing a protective layer having a diamond-like carbon or amorphous carbon structure, a carrier gas such as H ₂ or Ar is used with a hydrocarbon gas (methane, ethane, ethylene, acetylene, etc.) as a main material. Furthermore, the gas for supplying the additive element may be any gas that can be vaporized under reduced pressure, or any gas that 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 the gas supplying chlorine, CH ₃ Cl, CH ₂ Cl ₂ , CHCl ₃ , CCl ₄ or the like is used as the gas supplying chlorine, and CH ₃ Br or the like is used as the 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.

  The protective layer 5 having a diamond-like carbon or amorphous carbon structure is formed by a plasma CVD method, a glow discharge decomposition method, a photo CVD method, or a sputtering method using graphite as a target, using the gas as described above. The 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 (for example, Patent Document 9 (Japanese Patent Laid-Open No. 58-49609)) is known.

In the method of forming a protective layer mainly composed of carbon using the plasma CVD method, 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 an advantage that there is no problem when the protective layer is formed on the layer.
The thickness of the protective layer having a diamond-like carbon or amorphous carbon structure is desirably 0.5 μm or more and 3.0 μm or less.

In particular, the protective layer 5 in which a filler is dispersed in a resin is preferable. Fillers added to the protective layer 5 include organic and inorganic fillers.
Examples of organic fillers include fluororesin fillers such as polytetrafluoroethylene, silicone resin fillers, fillers mainly composed of carbon, and inorganic filler materials include copper, tin, aluminum, indium, etc. Metal oxides, silicon oxide, silica, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, tin oxide doped with antimony, metal oxides such as indium oxide doped with tin, Inorganic materials such as potassium titanate can be mentioned. In particular, it is advantageous to use an inorganic material or a filler material mainly composed of carbon. In particular, metal oxides are good for inorganic materials, and silicon oxide, aluminum oxide, titanium oxide, and the like can be used effectively. Furthermore, diamond filler can be used effectively for fillers mainly composed of carbon.

The higher the filler concentration of the protective layer, the better the abrasion resistance, but the better. However, the writing light transmittance is lowered, which may cause side effects. Therefore, it is approximately 50% by weight or less, preferably 30% by weight or less, based on the total solid content. The lower limit is usually 5% by weight.
The film thickness of the protective layer in which the filler is dispersed in the resin is suitably from 0.5 μm to 10 μm, and preferably from 1.0 μm to 6.0 μm.

<About the undercoat layer>
In the image carrier of the present invention, an undercoat layer can be provided between the conductive support 1 and the photosensitive layer 2 for the purpose of adhesion to the photosensitive layer 2 and prevention of moire. In general, the undercoat layer is mainly composed of a resin. However, considering that the photosensitive layer is coated with a solvent on these resins, the resin may be a resin having high solvent resistance with respect to a general organic solvent. desirable. 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 metal oxide filler such as titanium oxide, silicon oxide, aluminum oxide, zirconium oxide, tin oxide, or indium oxide may be added.

The undercoat layer can be formed using an appropriate solvent and coating method as in the above-described layers. Furthermore, in this invention, a silane coupling agent, a titanium coupling agent, a chromium coupling agent, etc. can also be used as an undercoat layer. In addition, the undercoat layer is formed by anodizing Al ₂ O ₃ , organic materials such as polyparaxylylene (parylene), and inorganic materials such as SiO ₂ , SnO ₂ , TiO ₂ , ITO, and CeO _2. Can also be used favorably. In addition, known ones can be used. The thickness of the undercoat layer is suitably from 0.1 to 5.0 μm.

Next, the image forming method and the image forming apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 13 is a schematic configuration diagram for explaining an embodiment of the image forming apparatus of the present invention. This image forming apparatus includes a latent image forming unit (exposure unit 7 and bias application) around an endless belt-like image carrier 6 stretched around a plurality of rollers including a driving roller and a driven roller. Means (not shown), a developing unit 8 as a developing unit, a transfer unit 9 as a transferring unit, a cleaning unit 10 as a cleaning unit, and a neutralizing unit 11 as a neutralizing unit. Image formation is performed by the image formation process as shown in (IV).

(I) A bias is applied to the upper electrode 3 of the image carrier 6 in the latent image forming unit, and light exposure according to image data is performed from the exposure unit 7 to perform optical writing. Even after optical writing, a bias is applied to the upper electrode of the image carrier 6 to form an electrostatic latent image.
(II) The bias application to the image carrier 6 is stopped, and the electrostatic latent image is developed with toner in the developing unit 8.
(III) The toner image developed on the image carrier 6 is transferred to a transfer medium such as paper by the transfer unit 9.
(IV) The toner remaining on the surface of the image carrier 6 is cleaned by the cleaning unit 10, and the residual potential on the surface of the image carrier 6 is neutralized by the neutralization unit 11.

Here, the image carrier 6 uses the image carrier having the structure described with reference to FIGS.
The exposure unit 7 that performs optical writing is composed of an exposure apparatus that uses a semiconductor laser (LD) or a light emitting diode (LED) as a light source, and more specifically, light that includes an LD light source, an optical deflector, and a scanning imaging optical system. It comprises a scanning exposure apparatus or an exposure apparatus comprising an LED light source (LED array) arranged in an array and an equal magnification imaging optical system (for example, a microlens array, a rod lens array, etc.).

The bias application in the step (I) is performed by applying bias application means (conductive members such as a conductive roller and a conductive brush connected to a bias power source) (not shown) at the end in the width direction of the image carrier 6. A bias is applied to the upper electrode 3. The bias at this time may be positive or negative.
In the step (II), the bias application is stopped, the float and the ground are set, an electrostatic latent image is formed, and the developing unit 8 forms a toner image.
In the step (III), the toner image may be directly transferred to a transfer medium such as paper by the transfer unit 9, or the toner image may be transferred to a transfer medium such as paper via an intermediate transfer member.
In the step (IV), the cleaning unit 10 cleans the toner remaining on the surface of the image carrier 6 with a cleaning means such as blade cleaning or brush cleaning. Further, the neutralization unit 11 neutralizes the surface of the image carrier 6 by neutralizing the surface of the image carrier 6 by light irradiation or by applying a bias having a polarity opposite to the bias applied in the step (I). To do.

  Although not shown in FIG. 13, the image forming apparatus stores a transfer medium such as paper and supplies a paper feeding unit that feeds the image forming process in accordance with the timing, paper or the like. A fixing unit for fixing the toner image transferred to the transfer medium, a paper discharge unit for discharging the fixed transfer medium, and the like are provided.

The image forming process using the image carrier of the present invention is not limited to the above example. At least the photosensitive layer 2 (or the photosensitive layer 2 and the charge holding layer 4) on the conductive support 1, The upper electrode (specifically, formed in a random pattern, stripe or grid, having a portion covering the photosensitive layer 2 (or charge holding layer 4) and a portion not covering the photosensitive layer (or charge layer) By using an image carrier 6 in which an upper electrode 3) and a protective layer 5 formed so as to cover the surface of the holding layer) with a predetermined pattern, a bias voltage is applied to the upper electrode 3 during light irradiation. Any process and configuration for forming an electrostatic latent image may be used.
By using such an image forming method and an image forming apparatus, it is possible to realize an image forming method and an image forming apparatus that are small in size and have little potential unevenness without generation of ozone, nitrogen oxides (NOx), and the like.

The image forming method and the image forming apparatus as described above may be fixedly incorporated in an image forming unit of a copying machine, a facsimile machine, a printer, or a complex machine thereof, but these apparatuses in the form of a process cartridge. It may be incorporated in.
A process cartridge is an apparatus (parts) that includes an image carrier in a cartridge and includes at least one of a latent image forming unit, a developing unit, a transfer unit, a cleaning unit, and a discharging unit. And is detachable from the main body of the image forming apparatus. Since this process cartridge can be easily removed and replaced, and can be easily recycled, the maintenance and maintenance of the image forming apparatus are facilitated, and there are also advantages in terms of environmental protection.

In the present invention, by using the image carrier, the image forming method, the image forming apparatus, and the process cartridge as described above, the conventional charging step (discharge of the outside of the image carrier) accompanied by discharge that generates ozone and NOx products. Therefore, the latent image forming process can be simplified and the mechanism for applying a bias during light irradiation can be reduced in size compared to the prior art described in Patent Document 7 above. Is possible.
Further, when a bias is applied from the outside to the surface of the image carrier by using a transparent external bias application member as described in Patent Document 7, foreign matter (between the surface of the image carrier and the external bias application member is Toner, developer, paper dust, etc.) may be present, which may cause uneven bias application, possibly causing density unevenness, and may damage the surface of the image carrier. In the carrier, the upper electrode 3 having a predetermined pattern is formed on the photosensitive layer 2 (or the charge holding layer 4), and the surface of the image carrier excluding the end of the image carrier is covered with the protective layer 5 to the upper electrode. Since the bias application is performed at the edge of the image carrier, foreign matter adhesion does not occur between the upper electrode and the lower layers, and uniform bias application can always be performed. Adverse effects such as No. Further, there is no fear that the surface of the image carrier is damaged.

  Hereinafter, the image carrier of the present invention will be described with reference to specific examples, but the embodiments of the present invention are not limited thereby.

{Examples of coating solution conditions for each layer}
[Photosensitive layer (single layer) coating solution]
-Bisphenol A type polycarbonate (Panlite TS2050: manufactured by Teijin Chemicals Ltd.).
-A hole transport material having the structure shown in [Chemical Formula 1] below.
-An electron transport material having the structure shown in [Chemical Formula 2] below.
• Oxotitanium phthalocyanine pigment.
Tetrahydrofuran.

<Mixing ratio (weight)>
Polycarbonate / hole transport material / electron transport material / oxotitanium phthalocyanine / tetrahydrofuran = 10/5/4/1/80

[Charge transport layer coating solution for photosensitive layer (lamination)]
-Bisphenol A type polycarbonate (Panlite TS2050: manufactured by Teijin Chemicals Ltd.).
-A hole transport material having the structure shown in [Chemical Formula 3] below.
-An electron transport material having the structure shown in [Chemical Formula 4] below.
Tetrahydrofuran.

<Mixing ratio (weight)>
Polycarbonate / hole transport material / electron transport material / tetrahydrofuran = 10/7/3/80

[Charge generation layer coating solution for photosensitive layer (lamination)]
• Oxotitanium phthalocyanine pigment.
-Butyral resin (ESREC BMS: manufactured by Sekisui Chemical Co., Ltd.).
Tetrahydrofuran.
-Cyclohexanone.

<Mixing ratio (weight)>
Oxotitanium phthalocyanine pigment / butyral resin / tetrahydrofuran / cyclohexanone = 5/2/100/100

[Charge retention layer and protective layer (1) Coating solution]
-Copolymer nylon resin (CM8000: manufactured by Toray).
-Methyl alcohol.
-Isobutyl alcohol.

<Mixing ratio (weight)>
Nylon resin / methyl alcohol / isobutyl alcohol = 4.5 / 80 / 15.5

[Protective layer (2) coating solution]
-Isocyanate (Takenate D140N: manufactured by Mitsui Takeda Chemical Co., Ltd.).
-Polyol (LZR170: manufactured by Fujikura Kasei Co., Ltd.).
·acetone.
-Cellosolve acetate.
-Methyl isobutyl ketone.

<Mixing conditions>
NCO / OH ratio = 1.0
Isocyanate + polyol / acetone / cellosolve acetate / methyl isobutyl ketone = 10/40/40/10

[Protective layer (3) coating solution]
-Isocyanate (Takenate D140N: made by Mitsui Takeda Chemical).
-Polyol (LZR170: manufactured by Fujikura Kasei).
-Titanium oxide (CR-EL: Ishihara Sangyo).
·acetone.
-Cellosolve acetate.
-Methyl isobutyl ketone.

<Mixing conditions>
NCO / OH ratio = 1.0
Isocyanate + polyol / titanium oxide / acetone / cellosolve acetate / methyl isobutyl ketone = 8/2/40/40/10

{Examples of coating conditions for each layer}
[Photosensitive layer (single layer)]
Coating method: dipping.
Film thickness: 30 μm.
Drying: Heat drying (130 ° C., 20 minutes).

[Charge transport layer of photosensitive layer (lamination)]
Coating method: dipping.
Film thickness: 30 μm.
Drying: Heat drying (130 ° C., 20 minutes).

[Charge generation layer of photosensitive layer (lamination)]
Coating method: spray.
Film thickness: 2.0 μm.
Drying: Heat drying (110 ° C., 20 minutes).

[Charge retention layer]
Coating method: dipping.
Film thickness: 2.0 μm.
Drying: Heat drying (100 ° C., 20 minutes).

[Protective layer (1)]
Coating method: spray.
Film thickness: 2.0 μm.
Drying: Heat drying (100 ° C., 20 minutes).

[Protective layer (2)]
Coating method: spray.
Film thickness: 2.0 μm.
Drying: Heat drying (150 ° C., 20 minutes).

[Protective layer (3)]
Coating method: spray.
Film thickness: 2.0 μm.
Drying: Heat drying (150 ° C., 20 minutes).

[Filming conditions for upper electrode (1)]
Film forming method: vacuum deposition method (mask).
Deposition source: Aluminum.
Electrode pattern: Striped electrodes (distance between electrodes 30 μm, electrode width 20 μm).

[Filming conditions for upper electrode (2)]
Film forming method: vacuum deposition method (after deposition, processing with excimer laser).
Deposition source: Aluminum.
Electrode pattern: Lattice electrode (interelectrode distance 25 μm, electrode width 20 μm).

[Filming conditions for protective layer (4)]
As a more specific example, the conditions for forming the protective layer (4) are shown below.
The substrate was set in a plasma CVD apparatus configured as shown in FIG. 14, and a protective layer was formed. Here, in FIG. 14, reference numeral 107 denotes a vacuum chamber of a 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 (comprising a pressure adjusting valve 121, a turbo molecular pump 122, and a rotary pump 123), and is kept at a constant pressure.
A reaction tank 150 is provided in the vacuum tank 107. Reference numerals 130 (131 to 134) denote gas lines to be introduced into the reaction tank 150, to which various material gas containers (not shown) are connected, which are respectively introduced into the reaction tank 150 from the nozzle 125 via the flow meter 129. The

  In the frame-like structure 102, a substrate 101 (101-1, 101-2... 101-n) in which the photosensitive layer (or the photosensitive layer and the charge holding layer) and an upper electrode are formed in a conductive support form. ). Each of the supports is arranged as a third electrode as will be described later. For the electrodes 103 and 113, a pair of power sources 115 (115-1 and 115-2) for applying a first alternating voltage is prepared. 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, a second alternating voltage is applied between the midpoint 105 and the third electrode, that is, the base 101 (101-1, 101-2... 101-n) or the holder 102 electrically connected thereto. A power source 119 is provided for this purpose. 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, ie, the support. The voltage output is about 100 W for a frequency of 150 KHz.

A protective layer (4) was formed under the following conditions.
C ₂ H ₄ flow rate: 90 sccm.
· _{H 2} flow rate: 150sccm.
· NF ₃ flow rate: 45sccm.
Reaction pressure: 0.02 torr.
First alternating voltage output: 200 W, 13.56 MHz.
-Bias voltage (DC component): -100V.
-Film thickness: 2.0 μm.

  As shown in Table 1 below, image carriers of Examples 1 to 9 were prepared by combining the above layers.

The image carriers of Examples 1 to 9 produced as described above were used in an image forming apparatus (Ricoh's combined machine: Imagio MF7070 remodeling machine (bias applied to upper electrode: electrostatic latent image forming +300 V, developing) 0V)) and image evaluation and paper passing test (A4, image area 7% lattice image) were performed.
First, since this is an image forming method using an image carrier having a novel configuration, whether or not an image can be initially formed is determined by a test chart NO. 3 was used for evaluation.
As a result, it was confirmed that an image could be formed by image evaluation incorporating all the image carriers of Examples 1 to 9.
Further, since there is no charging step with discharge, the odor of discharge products such as NOx and ozone could not be detected.
Thereafter, image evaluation and wear amount evaluation were performed. The amount of abrasion was determined by measuring the film thickness at 20 points on the photoconductor with an eddy current film thickness meter (Fisherscope MMS) and determining the film thickness reduction from the initial stage. The results are shown in Tables 2 and 3 below.

In the initial image evaluation shown in Table 2 below, in the image carrier of Examples 1 to 5, the protective layer was worn and the upper electrode disappeared at the stage of passing 12,000 to 16,000 sheets. did. Therefore, the paper passing test was stopped.
The image carriers of Examples 6 to 9 were evaluated after the initial image evaluation, up to 20,000 sheets as shown in Table 3 below.

Both image evaluations were performed visually after paper output.
-Halftone: ○ Good, △ Local unevenness occurs.
-Fine line reproducibility: ○ Good, Δ Locally generated image flow, × Overall image flow generated.

  As a result of the above evaluation, the image carriers of Examples 7 to 9 have good halftone and fine line reproducibility even after passing through 20,000 sheets, and the wear amount is 0.5 μm or less. did it.

1: Conductive support 2: Photosensitive layer 2a: Charge transport layer 2b: Charge generation layer 3: Upper electrode 3a: Striped electrode 3b: Lattice electrode 4: Charge holding layer 5: Protective layer 6: Image carrier 7: Exposure unit 8: Development unit 9: Transfer unit 10: Cleaning unit 11: Static elimination unit 101-1 to 101-n: Support body 102: Frame-shaped structure 103, 113: Electrode 104, 114: End of matching transformer 105: Transformer output side midpoint 107: Vacuum tank 108, 118: Hood 109: Gate valve 115: Power supply 116-1, 116-2: Matching transformer 117: Load / unload spare room 119: Power supply 120: Exhaust system 121: Adjustment Valve 122: Turbo molecular pump 123: Rotary pump 125: Gas introduction nozzle 126: Phase adjuster 129: Flow meter 130-134: Gas line 140: Alternating power supply system 150: Reaction tank

Japanese Patent Laid-Open No. 06-003921 JP-A-8-76559 JP-A-8-76559 JP-A-9-26681 Japanese Patent No. 3895514 Japanese Patent No. 3566275 JP 2007-178816 A JP 52-36016 A JP 58-49609 A

Claims (15)

An image carrier that is used for image formation and forms an electrostatic latent image,
The image carrier has a structure in which at least a photosensitive layer, an upper electrode having a portion covering the photosensitive layer and an uncoated portion, and a protective layer are sequentially laminated on a conductive support. ,
At the time of light irradiation from the image carrier surface side , a bias is applied to the upper electrode, the bias to the upper electrode is stopped, and the upper electrode is floated or grounded, whereby a latent image is formed. An image carrier characterized by being formed. An image carrier that is used for image formation and forms an electrostatic latent image,
The image carrier comprises, on a conductive support, at least a photosensitive layer, a charge retention layer, an upper electrode having a portion covering and not covering the charge retention layer, and a protective layer sequentially. Has a laminated structure,
At the time of light irradiation from the image carrier surface side , a bias is applied to the upper electrode, the bias to the upper electrode is stopped, and the upper electrode is floated or grounded, whereby a latent image is formed. An image carrier characterized by being formed. An image carrier that is used for image formation and forms an electrostatic latent image,
The image carrier has a structure in which at least a photosensitive layer, an upper electrode formed in a stripe shape on the photosensitive layer, and a protective layer are sequentially laminated on a conductive support.
At the time of light irradiation from the image carrier surface side , a bias is applied to the upper electrode, the bias to the upper electrode is stopped, and the upper electrode is floated or grounded, whereby a latent image is formed. An image carrier characterized by being formed. An image carrier that is used for image formation and forms an electrostatic latent image,
The image carrier has a structure in which at least a photosensitive layer, a charge retention layer, an upper electrode formed in a stripe shape on the charge retention layer, and a protective layer are sequentially laminated on a conductive support. ,
At the time of light irradiation from the image carrier surface side , a bias is applied to the upper electrode, the bias to the upper electrode is stopped, and the upper electrode is floated or grounded, whereby a latent image is formed. An image carrier characterized by being formed. An image carrier that is used for image formation and forms an electrostatic latent image,
The image carrier has a structure in which at least a photosensitive layer, an upper electrode formed in a lattice shape on the photosensitive layer, and a protective layer are sequentially laminated on a conductive support.
At the time of light irradiation from the image carrier surface side , a bias is applied to the upper electrode, the bias to the upper electrode is stopped, and the upper electrode is floated or grounded, whereby a latent image is formed. An image carrier characterized by being formed. An image carrier that is used for image formation and forms an electrostatic latent image,
The image carrier has a structure in which at least a photosensitive layer, a charge holding layer, an upper electrode formed in a lattice shape on the charge holding layer, and a protective layer are sequentially laminated on a conductive support. ,
At the time of light irradiation from the image carrier surface side , a bias is applied to the upper electrode, the bias to the upper electrode is stopped, and the upper electrode is floated or grounded, whereby a latent image is formed. An image carrier characterized by being formed. The image carrier according to any one of claims 1 to 6,
The image bearing member, wherein the photosensitive layer has a single layer structure, and the photosensitive layer having the single layer structure has a charge generation function and a charge transport function. The image carrier according to any one of claims 1 to 6,
The image bearing member, wherein the photosensitive layer has a laminated structure, and the photosensitive layer having the laminated structure includes a charge generation layer having a charge generation function and a charge transport layer having a charge transport function. The image carrier according to any one of claims 1 to 8,
An image bearing member, wherein the protective layer is a film having a diamond-like carbon or amorphous carbon structure. The image carrier according to any one of claims 1 to 8,
An image bearing member, wherein the protective layer is a film in which a filler is dispersed in a resin. A bias is applied to the upper electrode at the time of light irradiation from the image carrier surface side, and the bias to the upper electrode is stopped using the image carrier according to any one of claims 1 to 10. A latent image is formed by bringing the upper electrode into a floating state or a grounded state . 11. An image carrier according to claim 1, comprising a bias applied to the upper electrode when light is irradiated from the surface side of the image carrier, and the bias to the upper electrode is stopped. An image forming apparatus comprising means for forming a latent image by bringing the upper electrode into a float state or a ground state . The image forming apparatus according to claim 12.
At least light is irradiated from the image carrier surface side, and a bias is applied to the upper electrode during the light irradiation, the bias to the upper electrode is stopped, and the upper electrode is floated or grounded. Thus, a latent image forming unit having a means for forming a latent image, a developing unit for developing and developing the latent image on the image carrier, and transferring the visible image on the image carrier to a transfer medium And an image forming apparatus.   11. The image bearing member according to claim 1 is incorporated, and at least one of a latent image forming unit, a developing unit, a transfer unit, a cleaning unit, and a charge eliminating unit is provided. Process cartridge.   An image forming apparatus comprising the process cartridge according to claim 14 detachably.

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