JP2007240738A - Charging device, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-contact type charging device by which highly efficient charge is stably performed and an image forming apparatus by which high definition is created over a long term. <P>SOLUTION: The charging device 2 which is connected to a high voltage power supply 5 and charges a photoreceptor 1 has a non-contact charging member. The non-contact charging member is a substrate formed like a belt in the longitudinal direction of the photoreceptor and has an electron emission part in which thin film of Sp<SP>3</SP>bonded boron nitride is formed on the substrate. Thin film formation of the electron emission part is performed in an area longer than a photosensitive zone in the longitudinal direction of the photoreceptor on the non-contact charging member which is a substrate longer than the photosensitive area in the longitudinal direction of the photoreceptor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a charging device, a process cartridge, and an image forming apparatus, and in particular, a charging device that can perform highly efficient charging in a non-contact manner using Sp ³ -bonded boron nitride having excellent electron emission characteristics, and the charging device. The present invention relates to a mounted process cartridge or the like.

  Conventionally, in an image forming apparatus such as a copying machine or a laser beam printer, an electrophotographic photosensitive member as an object to be charged, an image carrier such as an electrostatic recording dielectric, and the like are uniformly charged to a required polarity and potential. A contact charging device is often used as a charging device that performs (including charge removal processing). In the contact charging device, a conductive charging member (contact charging member / contact charger) such as a roller type (charging roller), a fur brush type, a magnetic brush type, or a blade type is brought into contact with an image carrier, and the charging member The surface of the image carrier is charged to a predetermined polarity and potential by applying a predetermined charging bias.

  In the contact charging device, for example, as described in Patent Documents 1 to 4, a drum-shaped photosensitive member having an electroconductive elastic roller (hereinafter referred to as a charging roller) as a rotating charging member as an image carrier. The photosensitive drum is charged by being brought into pressure contact with the drum and applying a charging bias to the charging roller.

  However, according to the conventional contact charging device, the driven rotation of the charging roller is performed by friction between the surface of the photosensitive drum and the surface of the charging roller, and the charging roller is configured to be pressed by a spring member at the end. The following problems have occurred.

  That is, since the charging roller is pressed against the photosensitive drum by the spring members at both ends, the pressing force at both ends of the charging roller is inevitably larger than the pressing force at the center of the charging roller. Deflection occurs in the longitudinal direction. In this case, at the nip portion (contact portion) with the photosensitive drum, both ends of the charging roller have a large crushing amount, and conversely, the crushing amount is small at the central portion of the charging roller between both ends of the charging roller. That is, a difference in the amount of crushing occurs between both ends of the charging roller and the central portion of the charging roller, so that a phenomenon occurs in which the rotation radii are different between both ends of the charging roller and the central portion of the charging roller.

  In addition, the charging roller is pressed by spring members at both ends, and the applied pressure at the end of the charging roller is large. Therefore, the charging roller is mainly driven by the rotation of the photosensitive drum at the end of the charging roller. It is rotating. The charging roller edge and the charging roller center are friction driven at the same surface speed of the photosensitive drum, but the rotation radius is different between the charging roller edge and the charging roller center. ) And the rotation speed (angular velocity) of the end surface of the charging roller are different.

  As a result, this rotational speed difference causes uneven rotation between the charging roller end and the charging roller center, and the charging roller surface twists between the charging roller end and the charging roller center, There is a problem that a very small wrinkle is generated on the surface of the charging roller between the charging roller end and the charging roller center.

When the image forming apparatus is used for a long period of time, the toner as a developer for visualizing the electrostatic latent image formed on the surface of the photosensitive drum, A large amount of dirt such as paper dust of a recording paper used as a recording medium for recording a toner image of an electrostatic latent image visualized by toner adheres, and the surface of the charging roller becomes dirty. As a result, the surface of the photosensitive drum cannot be uniformly charged, resulting in a problem that charging failure occurs. This is a problem caused solely by the principle of such a contact-type charging device.
Japanese Patent Laid-Open No. 9-101652 JP 2000-31002 A JP 2000-356931 A JP 2002-123062 A

  In order to solve the problem caused by the principle of the contact charging device described above, it is effective to employ a non-contact charging device. As a non-contact charging device, a corona charger has been conventionally known. However, this corona charger has a disadvantage that it is necessary to apply a high voltage.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a non-contact type charging device that can stably perform highly efficient charging, and to realize an image forming apparatus capable of producing high image quality over a long period of time.

  In order to achieve this object, the invention according to claim 1 is to form an electrostatic latent image by exposing the surface of the photoconductor, the charging device for charging the photoconductor, and the surface of the photoconductor charged by the charging device. An exposure device for recording, a developing device for imparting charged fine particles to the electrostatic latent image formed by the exposure device to visualize the electrostatic latent image, and a charged fine particle image visualized by the developing device A charging device comprising a non-contact charging member in an image forming apparatus, comprising: a transfer device that transfers to a medium; and a cleaning device that cleans the surface of the photoreceptor after transfer by the transfer device, the non-contact charging member Has an electron emission portion formed of a boron nitride-containing thin film.

According to a second aspect of the present invention, in the charging device according to the first aspect, the boron nitride is Sp ³ bonded boron nitride.

  According to a third aspect of the present invention, in the charging device according to the second aspect, the electron emission portion is formed as a thin film on the non-contact charging member.

  According to a fourth aspect of the present invention, in the charging device according to the third aspect, the non-contact charging member is a substrate formed in a band shape in a direction parallel to the longitudinal direction of the photoconductor. To do.

  According to a fifth aspect of the present invention, in the charging device according to the fourth aspect, the non-contact charging member is a substrate longer than a photosensitive region in a longitudinal direction of the photoconductor, and the electron emission portion is the photosensitive device. A thin film is formed in a region longer than the photosensitive region in the longitudinal direction of the body.

  According to a sixth aspect of the present invention, the charging device according to any one of the first to fifth aspects, the photosensitive member, the developing device, and the cleaning device are integrally configured. This is a featured process cartridge.

  According to a seventh aspect of the present invention, in the process cartridge according to the sixth aspect, the charging device is disposed at least 5 μm or more away from the surface of the photoconductor, and is a distance from the surface of the photoconductor. Is characterized in that it is installed to be 5 mm or less at the maximum.

  According to an eighth aspect of the present invention, in the process cartridge according to the sixth or seventh aspect, a part or all of the charging device, the photosensitive member, the developing device, and the cleaning device can be attached or detached. It was configured as described above.

  The invention described in claim 9 is characterized in that the process cartridge according to any one of claims 6 to 8 is configured to be detachable from the image forming apparatus.

  According to a tenth aspect of the present invention, the charging device according to any one of the first to fifth aspects or the process cartridge according to any one of the sixth to ninth aspects is mounted. An image forming apparatus.

  The invention according to claim 11 is the image forming apparatus according to claim 10, wherein the charging device according to any one of claims 1 to 5 is separated from the surface of the photoreceptor by at least 5 μm. It is installed and the distance from the surface of the photoconductor is 5 mm or less at the maximum.

  According to the present invention, a non-contact type charging device capable of stably performing highly efficient charging is provided, and an image forming apparatus capable of producing a high image quality over a long period of time is realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. A charging device will be described as the first embodiment, a process cartridge as the second embodiment, and an image forming apparatus as the third embodiment.

<Embodiment 1>
FIG. 1 is a diagram showing a schematic configuration and a positional relationship between a charging device and a photosensitive drum of the present embodiment, and is in an image forming apparatus using a Carlson process principle (electrophotographic process).

  A photosensitive drum 1, which is an image carrier as a member to be charged, is formed in a cylindrical shape using aluminum, nickel, or the like as a material, and drum shafts 1a and 1b provided at both ends in the axial direction are drum support members 3a and 3b. Are rotatably supported via bearings 4a and 4b. By forming a photosensitive material such as OPC (Organic Photo Conductor), amorphous Se, or amorphous Si on the surface of the photosensitive drum 1, a photosensitive layer is formed over the entire circumference in the longitudinal direction of the photosensitive drum 1. Then, an electrostatic latent image and a toner image are formed on the surface of the photosensitive drum 1.

  The photosensitive drum 1 is rotationally driven in the arrow direction R1 around the drum shafts 1a and 1b by a driving source M such as a motor, and the charging device 2 is connected to a high voltage power source 5. First, the surface of the photosensitive drum 1 is uniformly charged by the charging device 2 placed close to the surface. As will be described in detail later, the charging device 2 is formed by forming a thin film of boron nitride on a belt-like substrate. In addition, the charging device 2 is configured to cover the chargeable region slightly larger than the longitudinal direction of the photosensitive drum 1 in order to enable uniform charging in the axial direction (longitudinal direction) of the photosensitive drum 1. The More strictly, the chargeable area is formed slightly longer than the photosensitive area.

  FIG. 2 is a schematic configuration diagram illustrating an example of an image forming apparatus using the Carlson process principle (electrophotographic process) using the charging device of the present embodiment.

  In the image forming area of the photosensitive drum 1, scanning exposure is performed by the laser beam 6 output from the laser scanner 16 and controlled to be turned on / off according to the image information, and an electrostatic latent image is formed. The electrostatic latent image is developed and visualized by the developing sleeve 7 whose toner layer thickness is regulated by the developing blade 11 to become a toner image. This toner image is transferred to a recording medium 9 as a recording material such as recording paper by a transfer roller 8.

  The recording medium 9 onto which the toner image has been transferred is separated from the surface of the photosensitive drum 1 and conveyed to the fixing device 17 where it is introduced into the fixing nip portion between the heat fixing roller 18 and the pressure roller 19 pressed against this. The toner image is conveyed and fixed on the recording medium 9 by the heat from the heat fixing roller 18 and the pressure applied to the fixing nip portion. The recording medium 9 on which the toner image is fixed is discharged outside the image forming apparatus main body.

  On the other hand, after the toner image is transferred, the transfer residual toner remaining on the photosensitive drum 1 is removed by the cleaning blade 10 to prepare for the next image formation.

In the charging device of this embodiment, a boron nitride thin film is formed on a substrate in a strip shape in the axial direction (longitudinal direction) of the photosensitive drum. The inventor of the present application has found that the boron nitride thin film has excellent electron emission characteristics in the air when formed under certain special conditions. Therefore, a thin film or a band-like shape formed of this material can be suitably used as a non-contact charging device for an electrophotographic image forming process. Among these, Sp ³ -bonded 5H-BN is used as the most preferable material in the present embodiment. Hereinafter, this material will be described.

  The inventor of the present application has found the above materials while searching for a material that exhibits excellent electron emission characteristics as an optimal material for a non-contact charging device. It was found that among boron nitrides manufactured under specific conditions, when they are formed in a film shape, those having a surface shape with excellent field electron emission characteristics can be generated.

  That is, when boron nitride is generated and deposited on the substrate by a reaction from the gas phase, boron nitride is formed in a film shape on the substrate when irradiated with high-energy ultraviolet light in the vicinity of the substrate, and a tip is formed on the film surface. Boron nitride in the shape of a sharp point is generated and grown in a self-organized manner in the light direction at appropriate intervals, and the resulting film can easily generate electrons when an electric field is applied to it. Considering this kind of material, the electron-emitting material that is extremely excellent that can maintain the extremely stable state and performance without deterioration, damage, or dropout of the material while maintaining extremely high current density. It was confirmed and found out.

  Irradiation with ultraviolet light is indispensable for the material to form a surface shape excellent in field electron emission characteristics in a self-modeling manner by reaction from the gas phase. This will be clarified in the detailed conditions of material generation to be described later, but the reason is not necessarily clear at this stage. However, it can be considered as follows.

  Surface morphogenesis by self-organization is understood as a so-called “Turing structure” and appears under certain conditions where the surface diffusion of the precursor material and the surface chemical reaction compete. Here, it is considered that ultraviolet light irradiation is related to the photochemical promotion of both, and affects the regular distribution of initial nuclei. The growth reaction on the surface is promoted by irradiation with ultraviolet light, which means that the reaction rate is proportional to the light intensity. Assuming that the initial nucleus is hemispherical, the light intensity is large near the apex and the growth is promoted, whereas the light intensity is weakened and the growth is delayed at the peripheral part. This is considered to be one of the formation factors of the surface formation with a sharp tip. In any case, ultraviolet light irradiation plays an extremely important role, and it cannot be denied that this is an important point.

The method for producing this material will be described in detail below. CVD (Chemical Vapor Deposition) reaction vessel having a structure shown in FIG. 7, the electron emission characteristics suitable for use in the charging device of the present embodiment excellent Sp ³ binding boron nitride film body ^(Sp 3 -bonded 5H-BN ) Was used to carry out the gas phase reaction.

  In FIG. 7, a reaction vessel 45 includes a gas introduction port 46 for introducing a reaction gas and its dilution gas, and a gas outlet 47 for exhausting the introduced reaction gas and the like out of the vessel. And maintained at a reduced pressure below atmospheric pressure. A substrate 50 on which boron nitride is deposited is set in the gas flow path in the reaction vessel 45, and an optical window 48 is attached to a part of the wall of the reaction vessel 45 facing the substrate 50. The substrate is irradiated with an excimer ultraviolet laser (arrow in the figure).

The reaction gas introduced into the reaction vessel 45 is excited by ultraviolet light irradiated on the surface of the substrate 50, and a nitrogen source and a boron source in the reaction gas undergo a gas phase reaction, and the general formula: BN is formed on the substrate. shown, Sp ³ binding boron nitride ^(Sp 3 -bonded 5H-BN) is produced comprising a 5H polytypic form, precipitated, it grows into a film shape.

  In this case, the pressure in the reaction vessel 45 can be implemented in a wide range of 0.001 to 760 Torr. Further, the temperature of the substrate 50 installed in the reaction space can be carried out in a wide range of room temperature to 1300 ° C., but the pressure is low and high in order to obtain the desired reaction product with higher purity. It is preferable to carry out at temperature.

  In addition, it is also a good method to irradiate with plasma when irradiating the substrate surface or a space region in the vicinity thereof with ultraviolet light for excitation. In FIG. 7, the plasma torch 49 shows this aspect, and the reaction gas inlet 46 and the plasma torch 49 are integrated toward the substrate 50 so that the reaction gas and the plasma are irradiated toward the substrate. Is set.

Hereinafter, description will be made based on more specific conditions. However, the conditions disclosed below, merely be those disclosed as an aid to understanding suitably applied Sp ³ binding boron nitride film body to the present invention ^{(Sp 3 -bonded 5H-BN)} , this It goes without saying that the present invention is not limited only by the conditions.

[Generation condition example 1]
A diborane flow rate of 10 sccm and an ammonia flow rate of 20 sccm were introduced into a mixed dilute gas flow having an argon flow rate of 2 SLM and a hydrogen flow rate of 50 sccm, and the temperature was maintained at 800 ° C. by heating in an atmosphere maintained at a pressure of 30 Torr by exhausting simultaneously with a pump. Excimer laser ultraviolet light was irradiated onto the silicon substrate (see FIG. 7). In this way, a desired thin film was obtained with a synthesis time of 60 minutes. As a result of identifying the thin film product by the X-ray diffraction method, the crystal system of this sample is hexagonal, and it is a 5H type polymorphic structure with Sp ³ bond, and the lattice constants are a = 2.52Å and c = 10.5Å. Met.

  As a result of observation with a scanning electron microscope image, this thin film is self-shaped with a unique surface shape covered with a conical protrusion structure (0.001 μm to several μm in length) with a sharp tip that tends to cause electric field concentration. Formation was observed.

In order to investigate the field electron emission characteristics of this thin film, a columnar metal electrode having a diameter of 1 mm was separated from the surface by 30 μm, a voltage was applied between the thin film and the electrode in vacuum, and the amount of electron emission was measured. The current density increased at 15-20 (V / μm), and at 20 (V / μm), it was saturated at the limit current value (equivalent to 1.3 A / cm ² ) of the high voltage power supply for measurement. Became clear.

  Further, when the time change of the current value at this time was examined, the current value was slightly fluctuated for about 15 minutes, but the average current value was maintained, and the current value due to material deterioration was maintained. No decrease was observed, confirming that the material was stable. Furthermore, even if this evaluation was performed in the air, almost the same characteristics were shown.

[Comparative Example 1]
For comparison, the field electron emission characteristics of a portion of the thin film that was simultaneously produced under the same conditions as those in Production Condition Example 1 except for the irradiation with ultraviolet light were examined. As a result, the threshold electric field intensity at the start of electron emission is 42 (V / μm), which is significantly higher than 15 (V / μm) in the case of generation condition example 1 manufactured by performing ultraviolet light irradiation. I understood. Moreover, when this part was observed with the scanning electron microscope, the damage and peeling of the thin film by field electron emission were seen. On the other hand, no damage was found in the portion showing the protruding surface shape grown under ultraviolet light irradiation after the field electron emission experiment.

[Generation condition example 2]
In an atmosphere maintained at a pressure of 30 Torr by introducing a diborane flow rate of 10 sccm and an ammonia flow rate of 20 sccm into a mixed dilution gas flow with an argon flow rate of 2 SLM and a hydrogen flow rate of 50 sccm, and simultaneously evacuating with a pump, the output is 800 w and the frequency is 13.56 MHz. RF plasma was generated, and excimer laser ultraviolet light was irradiated onto a silicon substrate maintained at 900 ° C. by heating (see FIG. 7). In this way, a thin film product was obtained with a synthesis time of 60 minutes. As a result of identifying this product by the same method as in Production Condition Example 1, the crystal system was hexagonal, a 5H polymorphic structure with Sp ³ bonds, and the lattice constants were a = 2.5 ＝ and c = 10. It was 4cm.

  As a result of observation with a scanning electron microscope image, this thin film is self-shaped with a unique surface shape covered with a conical protrusion structure (0.001 μm to several μm in length) with a sharp tip that tends to cause electric field concentration. Formation was observed.

In order to investigate the field electron emission characteristics of this thin film, a cylindrical metal electrode having a diameter of 1 mm was separated from the surface by 40 μm, a voltage was applied between the thin film and the electrode in vacuum, and the amount of electron emission was measured. As a result, an increase in current density was observed at an electric field strength of 18-22 (V / μm), and the limit current value (equivalent to 1.3 A / cm ² ) of the high voltage power supply for measurement was observed at 22 (V / μm). It became clear that it was saturated. Similar results were obtained in air evaluation. That is, it was confirmed that a stable material was obtained as in Production Condition Example 1.

Or Sp ³ binding boron nitride film body formed ^(Sp 3 -bonded 5H-BN) as is being deposited on the Si substrate so as to cover more than photoconductor region as described above, the substrate In the case where Si is used, it is disadvantageous in cost to cover the photosensitive region (for example, 210 mm to 300 mm or more) corresponding to the paper width with one substrate. In that case, the above-mentioned materials formed on a short strip-shaped Si substrate are connected to form a belt-shaped charged region. Or the board | substrate which can cover the said area | region with one board | substrates, such as glass substrates other than Si, is used.

  The charging device according to the present embodiment performs charging at a distance of at least 5 μm from the surface of the photosensitive drum. If it is closer than this, from the viewpoint of mechanical accuracy, the distance between the two (the surface of the photosensitive drum and the pattern surface formed of the above-mentioned material of the charging device) cannot be accurately maintained in parallel, and uniform charging is difficult. Because it becomes. On the other hand, the distance between the two is at most 5 mm. This is because if the distance exceeds 5 mm, it is not practical in terms of charging efficiency.

As described above, Sp ³ binding boron nitride film body ^(Sp 3 -bonded 5H-BN) has excellent surface shape field electron emission characteristics, i.e., is self-shaped shape which exhibited a sharp state of the tip Since it can be formed as a thin film with a unique structure, it can be charged efficiently as a non-contact type charging device for electrophotographic photosensitive members, and there is a problem with conventional contact type charging devices. It is possible to solve the problem caused by the principle itself, and to realize an electrophotographic apparatus capable of producing high image quality over a long period of time.

<Embodiment 2>
The present embodiment is a process cartridge on which the charging device of the first embodiment is mounted.

  FIG. 3 is a diagram showing a schematic configuration of the process cartridge of the present embodiment. In the present embodiment as well, devices having the same functions as those in the first embodiment are denoted by the same reference numerals.

  The process cartridge 20 includes a photosensitive drum 1, a charging device 2, a developing sleeve 7, a developing blade 11, and a cleaning blade 10. The charging device 2 is arranged close to the photosensitive drum 1 and charges the surface of the photosensitive drum 1. Then, a laser beam 6 corresponding to the image information is exposed to the photosensitive drum 1 by an exposure unit (not shown) to form an electrostatic latent image, and the developing sleeve 7 applies toner to the electrostatic latent image formed on the photosensitive drum 1. The developing blade 11 coats the toner on the developing sleeve 7 with a uniform thickness. Further, the photosensitive drum 1 and the developing sleeve 7 rotate in the arrow direction R1 and the arrow direction R3, respectively. The cleaning blade 10 cleans transfer residual toner and the like on the photosensitive drum 1.

  In the process cartridge 20 of this embodiment, the photosensitive drum 1, the charging device 2, the developing sleeve 7, the developing blade 11, and the cleaning blade 10 are integrally formed as a cartridge, and the cartridge can be attached to and detached from the image forming apparatus main body. It is configured.

  In addition, a part or all of the photosensitive drum 1, the charging device 2, the developing sleeve 7, the developing blade 11, and the cleaning blade 10 may be configured to be detachable from the process cartridge 20. With such a configuration, maintainability is improved.

  FIG. 4 is a diagram illustrating a schematic configuration of an image forming apparatus in which the process cartridge according to the present exemplary embodiment is mounted on the main body of the image forming apparatus.

  On the charged photosensitive drum 1, an electrostatic latent image is written by a laser beam 6 corresponding to image information and is developed by a developing sleeve 7 to become a toner image (visible image). The toner image on the photosensitive drum 1 is transferred onto the recording medium 9 by the transfer roller 8 and then fixed on the recording medium 9 by the fixing device 17. The recording medium 9 on which the toner image is fixed is discharged outside the image forming apparatus main body. On the other hand, after the transfer, the transfer residual toner or the like is removed by the cleaning blade 10 to prepare for the next image formation.

  Although the above is the principle description of the digital image forming apparatus performed by digital exposure using a laser beam spot, the image forming apparatus to which the charging device of Embodiment 1 is applied is not necessarily such a digital image forming apparatus. The present invention is not only applied to the image forming apparatus, but also to an image forming apparatus of analog type line exposure or whole surface batch exposure which has been performed by a conventional analog copying machine.

<Embodiment 3>
The present embodiment is an image forming apparatus equipped with the charging device according to the first embodiment, but may be configured to be equipped with the process cartridge according to the second embodiment.

  FIG. 5 is a diagram illustrating a schematic configuration of an image forming unit in the image forming apparatus of the present embodiment. Here, an image of a full-color image forming apparatus of a dry type two-component development system in which photosensitive bodies as latent image carriers are arranged in tandem. The formation part is shown.

  In the image forming unit 101, a plurality of image forming units 106 for yellow (Y), magenta (M), cyan (C), and black (K) are juxtaposed above an intermediate transfer belt 105 that is an endless belt. ing. In each image forming unit 106, a charging device 162, an exposure unit 165, a developing device 163, a photoconductor cleaning device 164, and the like are disposed along the outer periphery of a drum-shaped photoconductor 161 provided for each color. In FIG. 5, Y, M, C, and K representing colors are added after the symbols of the respective parts to distinguish the image forming parts of the respective colors.

  The charging device 162 performs a charging process in the vicinity of the surface of the photoconductor 161, and the exposure unit 165 irradiates the surface of the photoconductor 161 with laser light from the exposure device 107 for image information. The developing device 163 visualizes and visualizes the electrostatic latent image formed by exposing the surface of the photoconductor 161 by applying a toner as a charged fine particle color material, and the photoconductor cleaning device 164 performs post-transfer. The toner remaining on the surface of the photoreceptor 161 is removed and collected.

  FIG. 6 is a diagram showing a schematic configuration of the entire image forming apparatus of the present embodiment.

  An image forming unit 101 is disposed almost at the center of a four-tandem color image forming apparatus MFP (Multi Function Peripheral). A sheet feeding unit 102 is disposed immediately below the image forming unit 101. A paper feed tray 121 is provided at each stage. A reading unit 103 that reads a document is disposed above the image forming unit 101. A paper discharge tray 104, which is a paper discharge storage unit, is provided on the downstream side (left side in the drawing) of the image forming unit 101 in the paper conveyance direction, and the discharged recording paper on which images have been formed is stacked.

  As an image forming process, an image for each color is formed on the intermediate transfer belt 105, and four colors are superimposed on the intermediate transfer belt 105 to form one color image. First, yellow (Y) toner is first developed by the yellow (Y) image forming unit 106 and transferred onto the intermediate transfer belt 105 by the primary transfer device 166. Next, the magenta (M) image forming unit 106 develops the magenta (M) toner and transfers the toner onto the intermediate transfer belt 105. Subsequently, cyan (C) toner is developed by the cyan (C) image forming unit 106, transferred onto the intermediate transfer belt 105, and finally black (K) toner is developed, onto the intermediate transfer belt 105. By transferring, a full-color toner image in which four colors are superimposed is formed.

  The four-color toner images transferred onto the intermediate transfer belt 105 are transferred onto the recording paper 120 fed from the paper feeding unit 102 by the secondary transfer device 151 and fixed by the fixing device 108. The paper is discharged onto the paper discharge tray 104 by the paper discharge roller 141 or is conveyed to the double-sided device 109. During double-sided printing, the conveyance path is branched by the branching unit 191, and the recording paper 120 is reversed via the double-sided device 109. Reference numeral 192 denotes a reverse paper discharge path from the duplex device 109. Then, the paper skew is corrected by the registration roller 123, and the image forming operation on the back surface is performed in the same manner as the image forming operation on the front surface. On the other hand, after the full-color toner image is transferred, the toner remaining on the surface of the intermediate transfer belt 105 is removed and collected by the intermediate transfer belt cleaning device 152.

  In the paper feeding unit 102, unused recording paper 120 is stored in the paper feeding tray 121, and one end thereof swings to the bottom of the paper feeding tray 121 until the uppermost recording paper 120 contacts the pickup roller 125. The other end of the bottom plate 124 supported is raised. As the paper feed roller 126 rotates, the uppermost recording paper 120 is pulled out from the paper feed tray 121 by the pickup roller 125 and is transported by the paper feed roller 126 to the registration roller 123 side via the vertical transport path 127. The

  The registration roller 123 temporarily stops the conveyance of the recording paper 120 and sends out the recording paper 120 at a timing so that the positional relationship between the toner image on the intermediate transfer belt 105 and the leading edge of the recording paper 120 becomes a predetermined position. The registration roller 123 functions in the same manner for the recording paper 120 conveyed from the manual feed tray 184 in addition to the recording paper 120 from the vertical conveyance path 127. In FIG. 6, reference numeral 181 denotes a branching claw, and reference numeral 182 denotes a jammed paper discharge tray. When a jam occurs on the downstream side of the vertical conveyance path 127, the branching claw 181 operates and a sheet is fed to the paper discharge tray 182. Has the function of deriving.

  In the reading unit 103, the first traveling body 132 and the second traveling body 133 mounted with a document illumination light source and a mirror reciprocate in order to perform scanning scanning of a document (not shown) placed on the contact glass 131. To do. The image information scanned by the first traveling body 132 and the 2133 is condensed on the image plane of a CCD (Charge Coupled Device) 135 installed behind by the lens 134 and read by the CCD 135 as an image signal. The read image signal is digitized and subjected to image processing.

  Here, the reading density can be read at a density of 300 dpi, 600 dpi, and 1200 dpi as necessary in the full-color image forming apparatus of the present embodiment, and the reading density is selected. Further, after being filtered by the three primary color filters of red (R), green (G), and blue (B), it is read as an image signal by the CCD 135 and is taken in as color image data.

  Then, based on the image-processed signal, optical writing is performed on the surface of the photoreceptor 161 by light emission of a laser diode (not shown) in the exposure device 107, and an electrostatic latent image is formed. The optical signal from the laser diode reaches the photosensitive member 161 (photosensitive member for yellow (Y), magenta (M), cyan (C), and black (K), respectively) through a known polygon mirror or lens. Further, an ADF (Auto Document Feeder) 136 that automatically feeds the document onto the contact glass is attached to the upper portion of the reading unit 103.

  The above-described embodiment is a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above-described embodiment alone, and various modifications are made without departing from the gist of the present invention. Implementation is possible.

  According to the above embodiment, the photosensitive member, the charging device for charging the surface of the photosensitive member, the exposure device for exposing the charged surface to form an electrostatic latent image, and the charged fine particles on the electrostatic latent image. A developing device for applying and developing the electrostatic latent image, a transfer device for transferring the visualized charged fine particle image to the recording material, a fixing device for fixing the transferred charged fine particle image to the recording material, In an image forming apparatus comprising a cleaning device that cleans the surface of a photoreceptor after transfer and a transport unit that transports a recording medium to each device region, the charging device has an electron emission portion formed of a boron nitride-containing thin film. As a result, a novel non-contact charging image forming apparatus is realized.

  Further, according to the above-described embodiment, in such an image forming apparatus, since the photosensitive member, the charging device, the developing device, and the cleaning device are integrated into a cartridge, the configuration of the image forming apparatus has a simple unit configuration. Realized.

  Further, according to the above-described embodiment, in such an image forming apparatus, since the cartridge can be attached and detached, improvement in maintainability is realized.

Further, according to the above-described embodiment, in such an image forming apparatus, since boron nitride is Sp ³ bonded boron nitride, highly efficient charging that is not conventionally performed can be performed in a non-contact manner. It becomes possible.

  Further, according to the above embodiment, in such an image forming apparatus, the charging area of the charging device covers an area longer than the photosensitive area in the longitudinal direction of the photosensitive member. Therefore, it is possible to secure a sufficient charge and uniformity due to this, and an image forming apparatus with high image quality is realized.

  According to the above-described embodiment, in the process cartridge used in such an image forming apparatus, the photosensitive member, the charging device, the developing device, and the cleaning device are integrally configured. The configuration is realized by a simple unit configuration.

  In addition, according to the above-described embodiment, in such a process cartridge, since any one of the photosensitive member, the charging device, the developing device, and the cleaning device can be attached and detached, improvement in maintainability of the process cartridge is realized. .

Further, according to the above embodiment, in such a process cartridge, since boron nitride is Sp ³ bonded boron nitride, it is possible to perform non-contact and highly efficient charging in a non-contact manner. It becomes.

  Further, according to the above-described embodiment, in such a process cartridge, the charging area of the charging device covers an area longer than the photosensitive area in the longitudinal direction of the photosensitive member. Charge with sufficient margin and uniformity due to this can be ensured, and an image forming apparatus with high image quality is realized.

1 is a diagram illustrating a schematic configuration and a positional relationship between a charging device and a photosensitive drum according to an embodiment of the present invention. 1 is a schematic configuration diagram of an image forming apparatus equipped with a charging device according to an embodiment of the present invention. 1 is a schematic configuration diagram of a process cartridge according to an embodiment of the present invention. 1 is a schematic configuration diagram of an image forming apparatus equipped with a process cartridge according to an embodiment of the present invention. 1 is a schematic configuration diagram of an image forming unit in an image forming apparatus according to an embodiment of the present invention. 1 is a schematic configuration diagram of an entire image forming apparatus according to an embodiment of the present invention. It is a figure for demonstrating the preparation methods of the non-contact charging member of the charging device which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 1a, 1b Drum axis | shaft 2 Charging device 3a, 3b Drum support member 4a, 3b Bearing 5 High voltage power supply 6 Laser beam 7 Developing sleeve 8 Transfer roller 9 Recording medium 10 Cleaning blade 11 Developing blade 16 Laser scanner 17 Fixing device 18 Heating Fixing roller 19 Pressure roller 20 Process cartridge 45 Reaction vessel 46 Gas inlet 47 Gas outlet 48 Optical window 49 Plasma torch 50 Substrate

Claims (11)

A photosensitive member; a charging device that charges the photosensitive member; an exposure device that exposes a surface of the photosensitive member charged by the charging device to form an electrostatic latent image; and an electrostatic latent image formed by the exposure device A developing device that applies charged fine particles to visualize the electrostatic latent image, a transfer device that transfers the charged fine particle image visualized by the developing device to a recording medium, and the transfer device that has been transferred by the transfer device. A charging device including a non-contact charging member in an image forming apparatus including a cleaning device for cleaning the surface of a photoreceptor,
The charging device according to claim 1, wherein the non-contact charging member has an electron emission portion formed of a boron nitride-containing thin film. The charging device according to claim 1, wherein the boron nitride is Sp ³ bonded boron nitride.   The charging device according to claim 2, wherein the electron emission portion is formed as a thin film on the non-contact charging member.   The charging device according to claim 3, wherein the non-contact charging member is a substrate formed in a band shape in a direction parallel to a longitudinal direction of the photoconductor. The non-contact charging member is a substrate longer than the photosensitive region in the longitudinal direction of the photoconductor,
The charging device according to claim 4, wherein the electron emission portion is formed as a thin film in a region longer than a photosensitive region in a longitudinal direction of the photoconductor.   6. A process cartridge comprising: the charging device according to claim 1; the photosensitive member; the developing device; and the cleaning device.   7. The charging device according to claim 6, wherein the charging device is installed at least 5 μm or more away from the surface of the photoconductor, and the distance from the surface of the photoconductor is at most 5 mm. Process cartridge according to.   8. The process cartridge according to claim 6, wherein a part or all of the charging device, the photosensitive member, the developing device, and the cleaning device are detachable.   9. The process cartridge according to claim 6, wherein the process cartridge is configured to be detachable from the image forming apparatus.   An image forming apparatus comprising the charging device according to any one of claims 1 to 5 or the process cartridge according to any one of claims 6 to 9.   6. The charging device according to claim 1, wherein the charging device is disposed at least 5 μm or more away from the surface of the photoconductor, and the distance from the surface of the photoconductor is at most 5 mm or less. The image forming apparatus according to claim 10, wherein the image forming apparatus is installed in an image forming apparatus.

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