JP2007121349A - Electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic apparatus which suppress the occurrence of adherence and filming over a long period of time, can prevent image defects, and is high in stability and durability. <P>SOLUTION: The electrophotographic apparatus is provided with at least a photoreceptor having a photoconductive layer, comprising a non-single crystal film whose base material comprises silicon atoms; a charging means for charging the surface of the photoreceptor; an exposure means for irradiating the charged photoreceptor with light; a developing means forming a toner image on the surface of the photoreceptor, according to the electrostatic latent image formed on the surface of the photoreceptor by the charging means and the exposure means; a transfer means for transferring the toner image to a resin-system intermediate transfer belt; and a cleaning means for removing residual the toner that remains on the surface of the photoreceptor. The electrophotographic device is further provided with a polishing means which holds magnetic polishing particles as major component on the outer circumferential surface of a magnetic roller and makes the magnetic roller rotate, and by rubbing the magnetic polishing particles on the photoreceptor and polish its surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophotographic apparatus using a photoconductor (hereinafter sometimes referred to as an a-Si photoconductor) having a photoconductive layer made of a non-single crystal material having a silicon atom as a base material. A charging unit for charging the surface of the body, an exposure unit for irradiating the charged photoconductor with light, and the surface of the photoconductor according to an electrostatic latent image formed on the surface of the photoconductor by the charging unit and the exposure unit. The present invention relates to an electrophotographic apparatus having a developing means for forming a toner image on the surface, a transfer means for transferring the toner image to a resin-based intermediate transfer belt, and a cleaning means for removing residual toner remaining on the surface of the photoreceptor. It is.

  As an image forming apparatus using an electrophotographic process, color image information and multicolor image information are separated into a plurality of color components, a toner image is formed for each color component, and these toner images are superimposed on an intermediate transfer belt. An image forming apparatus that forms a composite color image is known. An image forming apparatus using such an intermediate transfer belt can obtain an image with extremely small misalignment (color misregistration) of the component color images. Therefore, it is effective as a color image forming apparatus, a multicolor image forming apparatus, or an image forming apparatus having a color image forming function or a multicolor image forming function. Therefore, color copiers, color printers and the like using such image forming apparatuses have already begun to be supplied to the market.

As a photoreceptor that can be suitably used in such an electrophotographic apparatus, an a-Si photoreceptor can be mentioned. The a-Si photosensitive member has a Vickers hardness of 1500 to 2000 kg / mm 2.
It is very hard and has excellent durability, heat resistance and environmental stability. For this reason, it has become indispensable particularly for high-speed machines that require high reliability.

  However, in the electrophotographic process, not only toner but also various foreign substances such as fine paper powder, organic components precipitated from them, and corona products adhere to the surface of the photoreceptor, and in some cases a thin film (filming layer) ) Is formed, and there is a risk that a strip-like or speckled image defect may occur due to this.

  In general, widely used OPC photoconductors, etc., even if toner or other foreign matters are temporarily attached, the surface of the photoconductor is worn and a fresh surface constantly appears, thereby reducing the influence. , Does not matter on the image. On the other hand, since the surface of the a-Si photosensitive member is hardly worn, the surface of the photosensitive member is constantly exposed to an electrophotographic process during the period of use. It needs to be removed.

  In order to remove such adhesion of toner and foreign matter and prevent filming, the pressing pressure of the cleaning blade in the cleaning process is increased, or abrasive fine particles are externally added to the toner. Increasing the polishing power has been done.

  In addition, a technique is disclosed in which a contact-type charging unit is used in the charging process and the surface of the photoreceptor is polished by rubbing in the charging process (for example, Patent Document 1).

  In addition, a technique for polishing the surface of a photoreceptor by rubbing a toner containing abrasive particles held on a developing roller in a developing process is disclosed (for example, Patent Document 2).

  Further, the cleaning device includes a cleaning blade and a magnetic brush made of magnetic toner, and the abrasive particles supplied as an external additive of the toner are restrained in the magnetic brush by 10 weight percent or more to rub the surface of the photoreceptor. A technique for improving the polishing action at the blade portion by re-supplying the abrasive particles together with the toner to the surface of the photoreceptor is disclosed (for example, Patent Document 3).

Further, a technique for removing filming by rubbing with an elastic sponge roller having an abrasive is disclosed (for example, Patent Document 4).
JP 2002-174944 A Japanese Patent No. 3373376 JP 2004-021135 A JP-A-10-111629

  However, in the case of electrophotography using an a-Si photoreceptor and a resin-based intermediate transfer belt, it has been found that as the durability progresses, image density unevenness due to transfer may occur. As a result of intensive studies by the present inventors in order to identify the cause, it has been found that in the resin-based intermediate transfer belt, a part of the component may be detached by application of a transfer current. When the desorbed material adheres to the surface of the a-Si photoconductor, it is very difficult to remove, and the photoconductor surface cleaning means and polishing means mentioned in the above-mentioned conventional examples are completely It was found that there are cases where it cannot be removed.

  Further, desorption occurs depending on the transfer current value, and if there is a portion where the transfer current does not flow completely uniformly and the current is partially concentrated, the desorption in that portion is present on the surface of the a-Si photoreceptor. It has been found that there is a case where it adheres firmly. When such adhesion occurs, the adhered substance itself affects the image, resulting in an image defect, or a torque increase due to an increase in the frictional resistance of the cleaning blade, and the normal cleaning process is not performed and the blade is damaged. As a result, it has been found that there may be image defects due to band-like or spot-like density unevenness.

  That is, the combination of the a-Si photosensitive member and the resin-based intermediate transfer belt is a structure that is likely to cause adhesion and filming on the surface of the a-Si photosensitive member and is extremely strict with respect to cleaning. As a result, there was room for further improvement. In particular, in digital color machines, the number of images formed is not limited to text, but the opportunity to output images that require high-quality image quality, such as photographs and pictures, has been rapidly increasing, and specifications required for electrophotographic devices. Is growing higher than before. For this reason, even a slight image defect that is sufficiently permissible in a conventional analog machine or the like may be problematic for higher specifications required from a digital color machine.

  In the configuration in which the surface of the photosensitive member is polished by rubbing between the charging member and the photosensitive member as disclosed in Patent Document 1 or the like, the polishing is an auxiliary purpose. For this reason, for example, the conditions such as the material, shape, size, and surface coating of the charged particles, the peripheral speed difference from the surface of the photosensitive member, the nip width, and the like are limited by the main charging conditions. . Therefore, it has been difficult to obtain conditions optimized for polishing.

  In addition, with respect to polishing means using abrasive particles externally or internally added to the toner as described in Patent Document 2, Patent Document 3, etc., priority is given to the physical properties of the toner, conditions from the development process, transfer process, etc. Therefore, it was difficult to achieve conditions optimized for polishing.

  In addition, as described in Patent Document 4 or the like, the polishing using the abrasive held on the sponge roller or the rubber roller or the like is a configuration in which the distribution of the abrasive on the roller, the pressing pressure, etc. are likely to be uneven. It was. For this reason, there is room for improvement in order to completely remove a part and a strongly adhered material, such as a detachment from the intermediate transfer belt described above.

  Further, it is considered that the deposits can be removed by simply increasing the polishing force. However, increasing the polishing force leads to an increase in the amount of wear, and has a trade-off relationship with the life of the photoreceptor. Therefore, there has been a demand for a cleaning means that can completely remove only the deposit without increasing the amount of wear more than necessary.

  The present invention relates to an electrophotographic apparatus using an a-Si photosensitive member and a resin-based intermediate transfer belt, and in particular, efficiently removes desorbed material from the intermediate transfer belt, and prevents adhesion and filming over a long period of time. An object of the present invention is to provide a highly stable and highly durable electrophotographic apparatus capable of suppressing generation and preventing image defects.

  The present inventors have intensively studied to solve the above-described problems and find an electrophotographic method having high image quality, high durability, and high stability. As a result, it has been found that the method of rubbing the surface of the photoreceptor using magnetic powder as abrasive particles has a great effect in efficiently removing the detachment from the intermediate transfer belt. And in the structure which combined the a-Si photosensitive body and the resin-type intermediate transfer belt, it discovered that it was suitable to arrange | position such a grinding | polishing means, and came to complete this invention.

  That is, the present invention provides a photoconductor having a photoconductive layer made of a non-single crystal film based on silicon atoms, a charging means for charging the surface of the photoconductor, and irradiating the charged photoconductor with light. An exposure unit; a developing unit that forms a toner image on the surface of the photoconductor in accordance with an electrostatic latent image formed on the surface of the photoconductor by the charging unit and the exposure unit; and a toner-based intermediate transfer of the toner image In an electrophotographic apparatus having at least a transfer means for transferring to a belt and a cleaning means for removing residual toner remaining on the surface of the photoreceptor, magnetic abrasive particles are held as a main component on an outer peripheral surface of a magnetic roller, and the magnetic It further comprises a polishing means for polishing the surface of the photoconductor by rotating a roller and sliding the magnetic abrasive particles on the photoconductor.

  According to the present invention, in an electrophotographic apparatus using an a-Si photosensitive member and a resin-based intermediate transfer belt, it is possible to efficiently remove, in particular, desorbed material from the intermediate transfer belt, over a long period of time. The occurrence of adhesion and filming can be suppressed. As a result, it is possible to provide a highly durable electrophotographic apparatus that can maintain the surface state of the photoreceptor well, prevent image defects over a long period of time, and have excellent image quality stability. And the reliability of the image forming apparatus represented by the electrophotographic apparatus can be greatly improved.

Embodiments of the present invention will be described below in detail with reference to the drawings.
(Polishing means)
FIG. 1A is a schematic schematic cross-sectional view showing an example of a polishing means for polishing the surface of an electrophotographic photosensitive member from the magnetic abrasive particles used in the present invention, and FIG. It is a typical schematic sectional drawing which shows the detail of the principal part of a).

  In the polishing means shown in FIG. 1A, a magnetic roller 102 having a magnetic material is accommodated in a magnetic roller container 104. The magnetic roller 102 is fixed to a rotatable sleeve and a sleeve. Made of magnetic material. The magnetic abrasive particles 103 are held on the outer surface of the sleeve and held in a brush shape by the magnetic force of the magnetic material in the magnetic roller 102. The magnetic abrasive particles 103 held in a brush shape rub against the surface of the electrophotographic photosensitive member 101, thereby removing the deposits on the surface of the photosensitive member 101 and simultaneously polishing the surface of the photosensitive member 101. ing.

  The magnetic body inside the magnetic roller 102 is preferably formed in a cylindrical shape using a metal such as a normal ferrite magnet or a magnetic body such as a plastic magnet. In order to form a good brush-like magnetic abrasive particle layer on the outer periphery of the magnetic roller, it is preferable to use a multipolar magnetic material.

  In addition, when a magnetic material having a low magnetic flux line density is used, the flowability of the head of the magnetic abrasive particles generated on the outer peripheral surface of the magnetic roller 102 is increased, so that the concave portion having a fine shape on the surface of the electrophotographic photosensitive member is obtained. It becomes easy to selectively enter the surface, and the fine shape after polishing becomes a round shape. On the other hand, when a magnetic material with a high magnetic flux line density is used, the fluidity of the head portion is lowered, so that the high convex portion is easily polished in the fine shape, and the fine shape after polishing is The convex portion has a flattened shape. Therefore, the magnetic flux line density of the magnetic material must be appropriately selected depending on the shape of the surface of the electrophotographic photosensitive member. However, if the magnetic flux line density is too low, the magnetic abrasive particles cannot be maintained on the surface of the magnetic roller 102. It is preferable to use a magnetic material having a surface of 300 G or more on the magnetic roller 102 surface.

  As shown in FIG. 1B, the layer thickness of the magnetic abrasive particles 103 covering the surface of the magnetic roller 102 is controlled by the interval (SB distance) between the magnetic roller 102 and the plate-like magnetic body regulating blade 105. The nip width of the magnetic abrasive particle layer on the electrophotographic photoreceptor 101 (the circumferential width at the contact portion between the electrophotographic photoreceptor and the magnetic abrasive particles) affects the polishing rate and the shape after polishing. By controlling stably, polishing with high stability and reproducibility becomes possible. 1 can be easily realized by controlling the SB distance and the SD distance which is the distance between the electrophotographic photosensitive member 101 and the magnetic roller 102 as the nip width control means. Since the polishing rate increases when the nip width is widened and decreases when the nip width is narrowed, the SB distance and the SD distance must be appropriately selected. However, from the viewpoint of preventing contact between the magnetic roller 102 and the electrophotographic photosensitive member, the SB distance and The SD distance is preferably 100 μm or more, and the polishing rate is saturated when the nip width is widened. Therefore, the SB distance is preferably 1500 μm or less.

  The outer periphery of the magnetic roller 102 is covered with magnetic abrasive particles 103 attracted by a magnetic force. As the magnetic abrasive particles, it is generally possible to use magnetic abrasive particles such as ferrite and magnetite, and well-known magnetic toner carriers. If the surface of the magnetic abrasive particles is coated with a resin film, etc., the friction between the electrophotographic photosensitive member and the magnetic abrasive particles will decrease, and the polishing rate will decrease, so magnetic abrasive particles that are not coated with the magnetic abrasive particle surface will be used. It is preferable to do.

  The shape of the magnetic abrasive particles can be broadly classified into spherical magnetic abrasive particles such as a sintered body and irregular magnetic abrasive particles such as those obtained by pulverizing the sintered body. The amorphous magnetic abrasive particles have a higher polishing rate than the spherical magnetic abrasive particles because the frictional resistance between the surface of the electrophotographic photosensitive member and the magnetic abrasive particles increases. For this reason, the shape of the magnetic abrasive particles must be appropriately selected depending on the polishing rate and the like.

  Furthermore, the particle size of the magnetic abrasive particles must be appropriately selected depending on the surface shape of the electrophotographic photoreceptor before polishing, the target surface shape after polishing, and the like. This will be described with reference to FIGS.

  FIG. 2 is an example of an AFM image observed in a 10 μm × 10 μm field of view on the surface of the a-Si photosensitive member. In the AFM image of FIG. 2, a crest having a width of about 1 to 2 μm and a trough having a width of about sub μm can be seen. When the surface of the a-Si photosensitive member having such a fine surface shape is polished with magnetic abrasive particles having a particle size distribution (number ratio of particle sizes) shown in FIG. 4, the particle size of the magnetic abrasive particles is larger than the width of the valley. Since it is fine, the valley can also be polished, and the surface shape after the polishing is rounded like the AFM image shown in FIG.

  It is considered that the deposits generated in the image forming process adhere more to the valleys than to the peaks. In order to remove these deposits efficiently, those that can be polished uniformly to the valley are preferable. Accordingly, the particle size of the magnetic abrasive particles may be set to 1 μm or less so that the cumulative frequency in the particle size distribution is 90% as in the particle size distribution (number ratio of particle size) shown in FIG. preferable. By using magnetic abrasive particles with such a particle size distribution, it is possible to efficiently remove even the deposits that have penetrated into the back of the valley, making it possible to polish the crest and trough almost uniformly, and more than necessary. It is possible to prevent the surface of the photoreceptor from being worn.

  Further, in order to perform stable polishing even in the long-term durability of 1 million to 3 million or more, it is more preferable to provide means for supplying new magnetic abrasive particles in the magnetic roller container. The magnetic abrasive particles held by the magnetic roller basically remain in the polishing means while being held.

  However, particles that are relatively small in the particle size distribution or particles that have a relatively weak magnetic force may be attracted to the photoreceptor. Even if some magnetic abrasive particles attracted to such a photoreceptor are present, they are collected by a photoreceptor cleaner or returned to the polishing means after the next lap, which has a great influence on image formation. There is almost no.

  However, if the particle size distribution of the magnetic abrasive particles in the polishing means is greatly changed, the scraping ability of the deposit may be affected. Therefore, in order to maintain a stable scraping ability over a long period of time, a configuration in which fresh magnetic abrasive particles are periodically replenished and the particle size distribution is kept constant is preferable.

The polishing means does not always need to rub the surface of the photosensitive member and the magnetic abrasive particles during the image forming process, and means to keep the polishing means away from the surface of the photosensitive member so as not to rub when not polishing. May be provided. Thus, by retracting the polishing means, it is possible to remove only the deposits more efficiently without unnecessarily polishing the photoreceptor. Further, if necessary, a refresh mode for the surface of the photosensitive member may be set, and polishing may be performed periodically for a predetermined time or number of processes.
(Electrophotographic equipment)
An electrophotographic apparatus having an intermediate transfer belt 705 made of a resin belt will be described with reference to a schematic configuration diagram of FIG.

  This electrophotographic apparatus has a drum-type photoconductor 701 on which an electrostatic latent image is formed and a toner image is formed on the electrostatic latent image. Around the photoconductor 701, a primary charger 702 that uniformly charges the surface of the photoconductor 701 to a predetermined polarity and potential, and image exposure 703 is performed on the surface of the charged photoconductor 701 to perform electrostatic latent. An image exposure device (not shown) that forms an image is disposed.

  In addition, as a developing device for attaching and developing toner on the formed electrostatic latent image, a first developing device 704a for attaching black toner B, a developing device for attaching yellow toner Y, and magenta toner M are attached. A rotating type second developing unit 704b including a developing unit and a developing unit for attaching cyan toner C is disposed.

  Further, after transferring the toner image to the intermediate transfer belt 705, the adhering material on the photoconductor 701 is removed, and the above-described polishing means 700 for polishing and the photoconductor cleaner 706 for cleaning the surface of the photoconductor 701 and the photoconductor 701 are used. A static elimination exposure 707 for performing static elimination is provided.

  The photoreceptor cleaner 706 includes a cleaning blade and a second magnetic roller. The second magnetic roller holds the transfer residual toner collected by the cleaning device on the outer periphery thereof in a brush shape. The second magnetic roller plays a role of stabilizing the cleaning operation at the blade portion by resupplying the transfer residual toner to the surface of the photoreceptor.

  The magnetic roller of the polishing means 700 holds magnetic abrasive particles as a main component, whereas the magnetic roller of the photoconductor cleaner 706 holds transfer residual toner and toner external additives as main components. The point is different. For this reason, the amount of polishing of the photoreceptor due to rubbing by the photoreceptor cleaner 706 is smaller than the amount of abrasion due to rubbing by the polishing means 700.

  As the intermediate transfer belt 705, a material that includes a conductive filler in a resin serving as a base material is preferably used. Examples of the resin serving as the base material include resin materials such as polyimide, polyester, polyetherketone, nylon (polyamide), polycarbonate, polyvinylidene fluoride (PVDF), and fluoroethylene-ethylene copolymer (ETFE). These materials can be appropriately determined from mechanical strength, flexibility, durability, and the like, and may be laminated with an elastic material such as a rubber material.

  Examples of conductive fillers that impart conductivity include carbon black, metals (aluminum, nickel, copper, etc.) and their alloys, metal oxides (tin oxide, zinc oxide, etc.) and inorganic oxides (potassium titanate). Etc.). Carbon black is particularly preferable, and examples thereof include furnace black, ketjen black, and channel black. Further, a polymer having ionic conductivity may be mixed as a filler, or an ionic electrolyte may be contained as a filler.

  The intermediate transfer belt 705 is disposed so as to be driven to the photosensitive member 701 through a contact nip portion, and a primary image for transferring a toner image formed on the photosensitive member 701 to the intermediate transfer belt 705 is provided on the inner side. A transfer roller 708 is provided. The primary transfer roller 708 is connected to a bias power source (not shown) for applying a primary transfer bias for transferring the toner image on the photoreceptor 701 to the intermediate transfer belt 705.

  A secondary transfer roller 709 for further transferring the toner image transferred to the intermediate transfer belt 705 to the recording material 711 is provided around the intermediate transfer belt 705 so as to be in contact with the lower surface portion of the intermediate transfer belt 705. ing. A bias power supply for applying a secondary transfer bias for transferring the toner image on the intermediate transfer belt 705 to the recording material 711 is connected to the secondary transfer roller 709.

  Further, an intermediate transfer belt cleaner 710 is provided for cleaning residual toner remaining on the surface of the intermediate transfer belt 705 after the toner image on the intermediate transfer belt 705 is transferred to the recording material 711.

  The electrophotographic apparatus also includes a paper feed cassette 712 that holds a plurality of recording materials 711 on which an image is formed, and a recording material 711 that contacts the intermediate transfer belt 705 and the secondary transfer roller 709 from the paper feed cassette 712. And a transport mechanism for transporting through the nip portion. A fixing device 713 for fixing the toner image transferred onto the recording material 711 on the recording material 711 is disposed on the conveyance path of the recording material 711.

  As the primary charger 702, a corona discharger or the like is used.

  As an image exposure apparatus, a color separation / imaging exposure optical system for a color original image, a scanning exposure system using a laser scanner that outputs a laser beam modulated in accordance with a time-series electric digital pixel signal of image information, and the like are used. It is done. With such an exposure system, an electrostatic latent image is formed on the surface of the photoconductor by irradiating a light beam using a laser or LED as a light source for each pixel of a plurality of rows and columns of pixel matrix according to the image pattern. be able to.

  Next, the operation of this electrophotographic apparatus will be described.

  First, as shown by an arrow in FIG. 7, the photosensitive member 701 is rotationally driven counterclockwise at a predetermined peripheral speed (process speed), and the intermediate transfer belt 705 rotates clockwise at the same peripheral speed as the photosensitive member 701. Driven.

  The photosensitive member 701 is uniformly charged to a predetermined polarity and potential by the primary charger 702 during the rotation process, and then subjected to image exposure 703, whereby the surface of the photosensitive member 701 has a target color image. An electrostatic latent image corresponding to the first color component image (for example, a magenta component image) is formed. Next, the second developing device rotates, the developing device for attaching the magenta toner M is set at a predetermined position, and the electrostatic latent image is developed with the magenta toner M as the first color. At this time, the first developing device 704a is turned off and does not act on the photoreceptor 701, and does not affect the first color magenta toner image.

  In this way, the first color magenta toner image formed and supported on the photosensitive member 701 passes through the nip portion between the photosensitive member 701 and the intermediate transfer belt 705, and the primary transfer bias is biased (not shown). ) To the primary transfer roller 708, an intermediate transfer is sequentially performed on the outer peripheral surface of the intermediate transfer belt 705 by an electric field formed.

  The surface of the photoreceptor 701 after the transfer of the first color magenta toner image to the intermediate transfer belt 705 is rubbed by the polishing means 700 and further cleaned by the photoreceptor cleaner 706. Next, a second color toner image (for example, a cyan toner image) is formed on the cleaned surface of the photoreceptor 701 in the same manner as the first color toner image, and the second color toner image is formed. Is superimposed and transferred onto the surface of the intermediate transfer belt 705 on which the first color toner image is transferred. Similarly, a third color toner image (for example, a yellow toner image) and a fourth color toner image (for example, a black toner image) are sequentially superimposed and transferred onto the intermediate transfer belt 705 to correspond to the target color image. A composite color toner image is formed.

  Next, the recording material 711 is fed from the paper feed cassette 712 to the contact nip portion between the intermediate transfer belt 705 and the secondary transfer roller 709 at a predetermined timing, and the secondary transfer roller 709 contacts the intermediate transfer belt 705. At the same time, the secondary transfer bias is applied from the bias power source to the secondary transfer roller 709, so that the composite color toner image superimposed and transferred onto the intermediate transfer belt 705 becomes the recording material as the second image carrier. 711 is transferred. After the transfer of the toner image onto the recording material 711 is completed, the transfer residual toner on the intermediate transfer belt 705 is cleaned by the intermediate transfer belt cleaner 710. The recording material 713 onto which the toner image has been transferred is guided to a fixing device 715 where the toner image is heated and fixed on the recording material 711.

  In the operation of the electrophotographic apparatus, when the first to fourth color toner images are sequentially transferred from the photoreceptor 701 to the intermediate transfer belt 705, the secondary transfer roller 709 and the intermediate transfer belt cleaner 710 are moved to the intermediate transfer belt 705. You may make it keep away from.

  An electrophotographic color electrophotographic apparatus using such an intermediate transfer belt has the following characteristics.

First, there is little color misregistration in which the formation positions of the toner images of the respective colors are shifted during superposition. Further, as shown in FIG. 7, the toner image is transferred from the intermediate transfer belt 705 without the need to process and control the recording material 711 (for example, gripping, adsorbing, giving a curvature, etc.). A wide variety of recording materials 711 can be used. For example, various thicknesses from thin paper (40 g / m ² paper) to thick paper (200 g / m ² paper) can be selected and used as the recording material 711. In addition, recording materials 711 having various sizes can be used regardless of the width or the length. Furthermore, an envelope, a postcard, a label paper, or the like can be used as the recording material 711.

Further, the intermediate transfer belt 705 is excellent in flexibility, and can freely set the nip with the photoreceptor 701 and the recording material 711. Therefore, the intermediate transfer belt 705 has a high degree of freedom in design, and it is easy to optimize transfer efficiency and the like. There are features.
(A-Si photoconductor)
Next, the layer configuration of an electrophotographic photoreceptor (sometimes referred to as a photoreceptor) that can be suitably used in the electrophotographic method of the present invention will be described with reference to the schematic configuration diagram of FIG. To do.

  A photoconductor 500 shown in FIG. 5A includes a base 501, a photoconductive layer 502 and a surface layer 503 that are sequentially provided on the base 501.

  Further, as shown in FIG. 5B, a lower charge injection blocking layer 504 is provided on the base 501 in order to block the injection of charges from the base, and the photoconductive layer 502 is formed on the lower charge injection blocking layer 504. And a layer structure in which the surface layer 503 is sequentially provided. If necessary, the photoconductive layer 502 may have a two-layer structure including a first layer region and a second layer region from the substrate 501 side. In addition, the interface between the photoconductive layer 502 and the surface layer 503 may be continuously changed to perform interface control that suppresses interface reflection.

Further, as shown in FIG. 5C, a base 501, a lower charge injection blocking layer 504, a photoconductive layer 502, an upper charge injection blocking layer 505, and a surface layer 503 are sequentially formed on the base 501. An upper charge injection blocking layer 505 may be provided for the purpose of reducing the charge injection from the top and improving the chargeability, and a layer structure particularly suitable for the negatively charged electrophotographic photosensitive member. In addition, the interface between the photoconductive layer 502 and the upper charge injection blocking layer 505 and / or the interface between the upper charge injection blocking layer 505 and the surface layer 503 is subjected to interface control that continuously changes and suppresses interface reflection. Also good.
(A-Si photoconductor manufacturing apparatus)
The a-Si photosensitive member is produced by a generally known vacuum deposition method, sputtering method, ion plating method, thermal CVD method, photo CVD method, plasma CVD method or the like on a substrate. An a-Si photosensitive member having a layer structure as shown in FIG. 6 may be formed. Among them, the a-Si photosensitive member is suitable when using a plasma CVD method, that is, a method of applying a high frequency power of RF band or VHF band to a source gas and decomposing it by glow discharge to form a deposited film on a substrate. Can be produced.

  Next, an apparatus that can be used for the production of a photoreceptor suitable for the electrophotographic apparatus of the present invention and a method for producing the photoreceptor using the same will be described below.

  FIG. 6 is a configuration diagram schematically showing an example of a photoconductor manufacturing apparatus using a high frequency plasma CVD method (also abbreviated as RF-PCVD) using an RF band as a power supply frequency.

  This apparatus is roughly composed of a deposition apparatus 6100, a source gas supply system 6200, and an exhaust apparatus (not shown) for depressurizing the inside of the reaction vessel 6111. In a reaction vessel 6111 in the deposition apparatus 6100, a mounting table 6110 for mounting a cylindrical substrate 6112, a substrate heating heater 6113, a source gas introduction pipe 6114 are installed, and a high frequency power source 6120 is connected via a high frequency matching box 6115. It is connected to a cathode electrode 6111 that also serves as a reaction vessel.

  The source gas supply device 6200 includes source gas cylinders 6221 to 6226, valves 6231 to 6236, 6241 to 6246, 6251 to 6256, and mass flow controllers 6211 to 6216, and each source gas cylinder reacts via a valve 6260. The gas inlet pipe 6114 in the container 6111 is connected.

  Formation of the deposit film using this apparatus is performed by the following procedures, for example.

  First, the cylindrical substrate 6112 is installed in the reaction vessel 6111, and the inside of the reaction vessel 6110 is exhausted by an exhaust device (not shown) such as a vacuum pump. Subsequently, the temperature of the cylindrical substrate 6112 is controlled to a predetermined temperature of 200 ° C. to 350 ° C. by the substrate heating heater 6113.

  Next, the flow rate of the source gas for forming the deposited film is controlled by the gas supply device 6200 and introduced into the reaction vessel 6111. Then, a predetermined pressure is set by adjusting the exhaust speed.

  After the preparation for deposition is completed as described above, each layer is formed by the following procedure.

  When the internal pressure is stabilized, the high frequency power source 6120 is set to a desired power and supplied to the cathode electrode 6111 through the high frequency matching box 6115 to cause a high frequency glow discharge. An RF band of 1 to 30 MHz can be suitably used as a frequency used for discharge.

  Each material gas introduced into the reaction vessel 6111 is decomposed by this discharge energy, and a deposited film containing a predetermined silicon atom as a main component is formed on the cylindrical substrate 6112. After the formation of the desired film thickness, the supply of high-frequency power is stopped, the valves of the gas supply device are closed, the inflow of each source gas into the reaction vessel 6110 is stopped, and the formation of the deposited film is completed.

  By repeating the same operation a plurality of times, a photosensitive layer having a desired multilayer structure is formed. In order to make the film formation uniform, it is also effective to rotate the cylindrical base 6112 at a predetermined speed by a driving device (not shown) during the layer formation. Furthermore, it goes without saying that the gas species and valve operations described above can be changed according to the production conditions of each layer.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, the technical scope of this invention is not limited at all by these.
[Photoconductor Production Example 1]
Using the plasma CVD apparatus shown in FIG. 6, deposition consisting of a lower charge injection blocking layer, a photoconductive layer, and a surface layer on an aluminum cylinder (substrate) having a mirror finish of 84 mm in diameter under the conditions shown in Table 1. Films were sequentially laminated to produce a photoconductor having the layer structure shown in FIG.

  An electrophotographic apparatus having the configuration shown in FIG. 7 was prepared as an electrophotographic apparatus. More specifically, an apparatus modified based on a Canon electrophotographic apparatus iRC-6800 and modified to have a configuration in which a polishing means 700 is provided between an intermediate transfer belt 705 and a photoreceptor cleaner 706 was prepared for experiments. The polishing means is an apparatus having the above-described configuration as shown in FIG.

  The specific polishing conditions are as follows: the rotation speed of the magnetic roller is adjusted to 120 rpm, the SD distance is adjusted to 0.4 mm, and the SB distance is adjusted to 1.0 mm, and Cu-Zn ferrite manufactured by Dowa Iron Powder Industry Co., Ltd. is used as the magnetic polishing particles. The distribution shown in FIG. 4 was used as the particle size distribution (number ratio of particle size). For the intermediate transfer belt, a seamless belt containing a polyimide resin and carbon black as a conductive filler was used.

  By disposing the polishing means 700 between the intermediate transfer belt 705 and the photoreceptor cleaner 706, even when a part of the magnetic abrasive particles are attracted to the photoreceptor without being completely held in the polishing means, Therefore, the influence on the image forming process after the next round can be reduced. For this reason, when a corona charging unit is used as the charging unit, the polishing unit is preferably disposed between the intermediate transfer belt and the photoreceptor cleaner.

  The prepared electrophotographic apparatus was mounted with the photoconductor manufactured under the conditions described in Photoconductor Production Example 1, and a paper passing durability test of 3 million sheets was performed.

  As the electrophotographic process conditions during durability, the primary transfer current value was set to 300 μA, which is larger than the normal conditions. This is because the detachment from the intermediate transfer belt is likely to occur, and image defects due to adhesion of the detachment are likely to occur. The other process parameters were the automatic control conditions of the used electrophotographic apparatus main body.

  However, since the primary transfer current value of 300 μA exceeds the power supply capacity of the electrophotographic apparatus used, the primary transfer current was further modified to supply the primary transfer current from an external power source during durability.

During durability, image output for evaluation was performed for every 100,000 sheets, and image characteristics were evaluated. Since the electrophotographic process conditions at the time of image output for evaluation are the automatic control conditions of the used electrophotographic apparatus, the primary transfer current is remodeled so that the primary transfer current is supplied from the internal power supply of the apparatus. Image output. That is, all the electrophotographic process conditions including the primary transfer current value were automatically controlled under the conditions of the electrophotographic apparatus main body, and hand image output was performed. The image
(1) Black color, cyan single color, four color halftone images with a pixel density of 20% for each color (2) Black single color, cyan single color, four color halftone images for each color with a pixel density of 40% (3) Each color A gradation pattern with a pixel density of 60% and a black single color, cyan single color, and four halftone images (4) single color, with the pixel density gradually changing from 0 to 100%, was output to A3 paper. Using these images, the presence or absence of image defects such as image density unevenness, striped streaks, and spotted unevenness was evaluated. When density unevenness occurs, if the density unevenness of each color is overlapped, the density unevenness is emphasized as a difference in color. Therefore, the four-color halftone is evaluated more severely than the single-color halftone. The evaluation result is
A: Image failure is not confirmed at all, and it is excellent.

  B: It is excellent that only a slight image defect can be confirmed when viewed carefully.

C: A very slight image defect can be confirmed.
Judgment was made according to the judgment criteria consisting of The results are shown in Table 2.

  Further, in order to evaluate the wear performance of the photoreceptor, the film thickness of the surface layer of the photoreceptor was measured at the initial stage and after the end of the durability. For the film thickness, a reflection spectrum was measured using a multichannel spectrophotometer (MCPD-2000, manufactured by Otsuka Electronics Co., Ltd.), and the surface layer thickness was calculated from the refractive index of the surface layer material. Then, the amount of abrasion of the photoreceptor surface layer was determined from the difference between the film thickness before and after the durability.

The wear characteristics are
A: The amount of wear is less than 0.2 μm, which is very good.

  B: Excellent with an abrasion amount of 0.2 μm or more and less than 0.4 μm.

  C: A wear amount of 0.4 μm or more and less than 0.6 μm, which is sufficiently acceptable for practical use.

D: Wear of 0.6 μm or more, which may cause a practical problem.
Judgment was made according to the judgment criteria consisting of The results are also shown in Table 2.
<Comparative Example 1>
The electrophotographic apparatus having the configuration shown in Example 1 was removed from the electrophotographic apparatus, and electrophotographics having the configuration shown in Example 1 were prepared in all other respects.

  The prepared electrophotographic apparatus was mounted with a photoconductor manufactured under the conditions described in Photoconductor Production Example 1, and paper passing durability was performed under the same conditions as in Example 1. Then, image characteristic evaluation and wear characteristic evaluation were performed in the same manner as in Example 1.

The results are also shown in Table 2.
<Comparative example 2>
An electrophotography having the configuration shown in Comparative Example 1 was prepared.

The prepared electrophotographic apparatus was mounted with a photoconductor manufactured under the conditions described in Photoconductor Production Example 1, and paper passing durability was performed under the same conditions as in Example 1. In this comparative example, the photosensitive member was once removed every time 250,000 sheets passed, and abrasive grains made of cerium oxide (CeO ₂ ) having a particle size of about 0.3 to ₂ μm were dispersed in alcohol or the like. The surface of the photoreceptor was cleaned by rubbing with an abrasive (hereinafter abbreviated as acid wiping).

  Then, image characteristic evaluation and wear characteristic evaluation were performed in the same manner as in Example 1.

  The results are also shown in Table 2.

  In addition to the electrophotographic apparatus having the configuration shown in Example 1, an electrophotographic apparatus having a configuration in which moving means for retracting the polishing means was added was prepared. In the electrophotographic apparatus of this embodiment, during a normal image forming process, the magnetic abrasive particles are evacuated so as not to rub against the surface of the photoconductor, and a regularly set refresh mode of the photoconductor surface is executed. Only when it was rubbed.

  The refresh mode of the photosensitive member surface in this embodiment was executed for about 1 minute every time 1000 jobs were completed. When the refresh mode was executed, all the charging and exposure were turned off and the photoconductor was rotated at a normal peripheral speed (273 mm / sec) in the other state to operate the polishing means. The conditions of the polishing means were such that the rotation speed of the magnetic roller was 240 rpm, the SD distance was 0.4 mm, the SB distance was 1.0 mm, and the same magnetic abrasive particles as in Example 1 were used.

  The prepared electrophotographic apparatus was mounted with a photoconductor manufactured under the conditions described in Photoconductor Production Example 1, and paper passing durability was performed under the same conditions as in Example 1. Then, image characteristic evaluation and wear characteristic evaluation were performed in the same manner as in Example 1.

  The results are also shown in Table 2.

  An electrophotographic apparatus having the configuration shown in FIG. 8 was prepared as an electrophotographic apparatus. More specifically, based on the Canon electrophotographic apparatus iRC-6800, the primary charger 802 is modified to a well-known magnetic brush contact type charger for the experiment, and further, the primary charger 802 and the charge removal light 807 are replaced. In the meantime, it is a device modified so that the polishing means 800 is provided.

  As specific polishing conditions, the number of rotations of the magnetic roller was adjusted to 120 rpm, the SD distance was adjusted to 0.4 mm, and the SB distance was adjusted to 1.0 mm, and the same magnetic polishing particles as in Example 1 were used. For the intermediate transfer belt, a seamless belt containing a polyimide resin and carbon black as a conductive filler was used.

  When a magnetic brush contact type charger is used as the charging means, even if magnetic abrasive particles that cannot be held in the polishing means and are attracted to the photosensitive member are present, they are recovered by rubbing in the charging process. It is possible. Therefore, the polishing means can be disposed between the photoreceptor cleaner and the primary charger as shown in FIG. By disposing at this position, residual toner or the like is not mixed into the polishing means, and more stable polishing is possible. For this reason, when a magnetic brush contact type charger is used as the charging means, the polishing means is preferably arranged as shown in this embodiment.

  The primary charger 802 and the polishing means 800 are both magnetic brushes, but the magnetic particles they hold are clearly different. The magnetic particles used in the magnetic brush charger have a particle size of about 30 μm to 50 μm in order to ensure charging ability and charging stability in the charging process, and the surface thereof is adjusted to a phenol resin for resistance adjustment. What coated with the coating material which disperse | distributed carbon black was used. On the other hand, the magnetic abrasive particles used in the polishing means 800 are the same as those in Example 1, differing in particle size and not coated with a surface.

  As described above, the surface shape of the a-Si photosensitive member has a shape having a crest having a width of about 1 to 2 μm and a trough having a width of about sub μm. When a particle having a size of several tens of μm or more is rubbed against the surface of the photosensitive member having such a shape, the particle size of the particle is larger than the width of the valley, and the particle does not enter the valley. The crest is selectively rubbed. For this reason, even if the surface of the photoconductor is rubbed with particles having such a particle size, it is difficult to efficiently remove deposits that are thought to be attached to the valleys more than the peaks, Since only the surface is selectively rubbed and polished, uniform polishing is not performed on the peaks and valleys.

  Therefore, it is preferable not to polish as much as possible by rubbing between the magnetic particles having such a particle diameter and the surface of the photoreceptor. Therefore, in the configuration of this embodiment, with respect to the magnetic particles of the charger, the surface is coated with a resin-based material to reduce the polishing force, and the amount of polishing of the photosensitive member by rubbing with the charger is reduced. The amount of wear due to rubbing by the polishing means was reduced.

  The prepared electrophotographic apparatus was mounted with a photoconductor manufactured under the conditions described in Photoconductor Production Example 1, and paper passing durability was performed under the same conditions as in Example 1. Then, image characteristic evaluation and wear characteristic evaluation were performed in the same manner as in Example 1.

  The results are also shown in Table 2.

  In addition to the electrophotographic apparatus having the structure shown in Example 3, an electrophotographic apparatus having a structure in which moving means for retracting the polishing means was added was prepared. In the electrophotographic apparatus of this embodiment, during a normal image forming process, the magnetic abrasive particles are evacuated so as not to rub against the surface of the photoconductor, and a regularly set refresh mode of the photoconductor surface is executed. Only when it was rubbed.

  The refresh mode of the photosensitive member surface in this embodiment was executed for about 1 minute every time 1000 jobs were completed. When the refresh mode was executed, all the charging and exposure were turned off and the photoconductor was rotated at a normal peripheral speed (273 mm / sec) in the other state to operate the polishing means. The conditions of the polishing means were such that the rotation speed of the magnetic roller was 240 rpm, the SD distance was 0.4 mm, the SB distance was 1.0 mm, and the same magnetic abrasive particles as in Example 1 were used.

  The prepared electrophotographic apparatus was mounted with a photoconductor manufactured under the conditions described in Photoconductor Production Example 1, and paper passing durability was performed under the same conditions as in Example 1. Then, image characteristic evaluation and wear characteristic evaluation were performed in the same manner as in Example 1.

  The results are also shown in Table 2.

  An electrophotographic apparatus having the configuration shown in FIG. 9 was prepared as an electrophotographic apparatus. More specifically, the apparatus is based on a Canon electrophotographic apparatus iRC-6800, and is modified for experiments so that the polishing means 900 is provided in the second developing unit 904b. In the electrophotographic apparatus of this embodiment, the magnetic abrasive particles do not rub against the surface of the photoconductor during the structurally normal image forming process. Therefore, the refresh mode of the photoconductor surface is periodically set and only when it is executed. , I tried to rub.

  The refresh mode of the photosensitive member surface in this embodiment was executed for about 1 minute every time 1000 jobs were completed. When the refresh mode was executed, the polishing means was operated by rotating the photoconductor at a normal peripheral speed (273 mm / sec) with all charging and exposure turned off. The conditions of the polishing means were such that the rotation speed of the magnetic roller was 240 rpm, the SD distance was 0.4 mm, the SB distance was 1.0 mm, and the same magnetic abrasive particles as in Example 1 were used.

  The prepared electrophotographic apparatus was mounted with a photoconductor manufactured under the conditions described in Photoconductor Production Example 1, and paper passing durability was performed under the same conditions as in Example 1. Then, image characteristic evaluation and wear characteristic evaluation were performed in the same manner as in Example 1.

  The results are also shown in Table 2.

表２から明らかなように、研磨手段を配備しなかった比較例１に示した電子写真装置においては、耐久と共に付着物或はフィルミングに起因すると考えられるスジ状の画像不良が発生し、画像の判定ランクが低下する結果となった。又、耐久の途中で定期的に酸セリ拭き清掃を行った比較例２においても、比較例１に比べると画像不良の程度は軽減されているものの、耐久と共に付着物或はフィルミングに起因すると考えられるスジ状の画像不良が発生し、画像の判定ランクが低下してしまった。

As is apparent from Table 2, in the electrophotographic apparatus shown in Comparative Example 1 in which no polishing means was provided, streak-like image defects thought to be caused by adhesion or filming occurred as well as durability. As a result, the evaluation rank decreased. Further, even in Comparative Example 2 in which acid wiping and cleaning was periodically performed during the durability, although the degree of image failure was reduced as compared with Comparative Example 1, it was caused by adhesion or filming with durability. A possible streak-like image defect occurred, and the image judgment rank was lowered.

  As described above, in the electrophotographic apparatus having this configuration, there is a possibility that an image defect due to filming or filming caused by filming may occur, and that the object is completely removed by cleaning with acid scouring. I found out I couldn't do it.

  On the other hand, in the electrophotographic apparatus having the configuration shown in Examples 1 to 5 in which the polishing means of the present invention is provided in the electrophotographic apparatus, no such image defect occurred. That is, it can be seen that the electrophotographic apparatus of the present invention is very suitable for efficiently removing the desorbed material from the intermediate transfer belt attached with a very strong force. For this reason, even if long-term durability of up to 3 million sheets is performed under severer conditions with respect to adhesion where the primary transfer current is set larger than normal automatic control conditions, the occurrence of adhesion and filming is suppressed, It can be seen that the electrophotographic apparatus can prevent image defects and is highly stable and highly durable.

  As for the wear characteristics, Example 1 and Example 3 in which the polishing means was constantly rubbed with the surface of the photoreceptor resulted in a slightly larger amount of wear than the other examples. However, even if the surface layer thickness and wear rate remaining after durability were taken into consideration, the results were sufficiently excellent. Example 2 and Example 4 in which the rubbing means and the surface of the photoconductor were rubbed only during the image forming process without setting the regular photoconductor surface refresh mode. Regarding Example 5, it was a very excellent wear characteristic with a smaller amount of wear.

  As described above, in the electrophotographic apparatus of the present invention, the magnetic abrasive particles are rubbed against the surface of the photoreceptor, but it can be confirmed that the conventional level can be maintained generally without increasing the wear characteristics. . As a result, it can be seen that the polishing means of the present invention has a configuration that can efficiently remove only the strongly adhered deposit without polishing the surface of the photoreceptor more than necessary.

  This is because the magnetic abrasive particles formed in a brush shape on the surface of the magnetic roller are rubbed against the surface of the photoconductor with a certain degree of fluidity. It is presumed that the part is also rubbed with a substantially uniform force. As a result, it is possible to uniformly polish not only the convex portion but also the concave portion, and it is considered that the deposits that have penetrated deep into the concave portion can be efficiently removed.

(A) is a typical schematic sectional drawing of the grinding | polishing means which can be used suitably for this invention, (b) is a typical schematic sectional drawing which shows the detail of the principal part of (a). It is an AFM observation image of the a-Si photoreceptor surface. FIG. 5 is an AFM observation image of the surface of an a-Si photosensitive member polished using the magnetic powder having the particle size distribution of FIG. 4. It is a particle size distribution (number) of magnetic abrasive particles that can be suitably used in the present invention. (A) is a cross-sectional view showing an example of a layer structure of a photoreceptor preferably used in the present invention, (b) is a cross-sectional view showing an example of a layer structure of a photoreceptor suitably used in the present invention, and (c) is a cross-sectional view. FIG. 3 is a cross-sectional view showing an example of a layer structure of a photoreceptor preferably used in the present invention. It is a schematic block diagram which shows an example of the apparatus for manufacturing the photoreceptor suitably used for this invention. It is a schematic block diagram which shows an example of the electrophotographic apparatus of this invention. It is a schematic block diagram which shows an example of the electrophotographic apparatus of this invention. It is a schematic block diagram which shows an example of the electrophotographic apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Electrophotographic photoreceptor 102 Magnetic roller 103 Magnetic abrasive particle 104 Magnetic roller container 105 Magnetic body regulating blade 500 Electrophotographic photoreceptor 501 Base 502 Photoconductive layer 503 Surface layer 504 Lower charge injection blocking layer 505 Upper charge injection blocking layer 700,800 , 900 Polishing means 701, 801, 901 Photoconductor 702, 802, 902 Primary charger 703, 803, 903 Image exposure 704a, 804a, 904a First developer 704b, 804b, 904b Second developer 705, 805, 905 Intermediate Transfer belt 706, 806, 906 Photoconductor cleaner 707, 807, 907 Static elimination exposure 708, 808, 908 Primary transfer roller 709, 809, 909 Secondary transfer roller 710, 810, 910 Intermediate transfer belt cleaner 711, 811, 91 1 Recording material 712, 812, 912 Paper feed cassette 713, 813, 913 Fixing device

Claims (6)

A photoreceptor having a photoconductive layer composed of a non-single crystal film based on silicon atoms, a charging means for charging the surface of the photoreceptor, an exposure means for irradiating the charged photoreceptor with light, and the charging And a developing unit that forms a toner image on the surface of the photoconductor according to an electrostatic latent image formed on the surface of the photoconductor by the exposure unit, and a transfer unit that transfers the toner image to a resin-based intermediate transfer belt And an electrophotographic apparatus having at least cleaning means for removing residual toner remaining on the surface of the photoreceptor.
There is further provided a polishing means for holding the magnetic abrasive particles as a main component on the outer peripheral surface of the magnetic roller, and rotating the magnetic roller to rub the magnetic abrasive particles against the photoconductor to polish the surface of the photoconductor. An electrophotographic apparatus characterized by that.   2. The electrophotographic apparatus according to claim 1, wherein the polishing means is disposed between the transfer means and the cleaning means.   2. The electrophotographic apparatus according to claim 1, wherein the polishing means is disposed between a cleaning means and a charging means.   4. The electrophotographic apparatus according to claim 1, wherein the magnetic abrasive particles have a particle size of 1 μm or less at which the cumulative frequency in the number distribution of particle sizes is 90%.   The electrophotographic apparatus according to claim 1, wherein the polishing unit includes a unit that replenishes the magnetic abrasive particles.   The polishing means has moving means for retracting the magnetic roller from the surface of the photoreceptor, and retracts so that the surface of the photoreceptor and the magnetic abrasive particles do not rub when not being polished. The electrophotographic apparatus according to any one of claims 1 to 5.

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