JP2007057803A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of suppressing image defects by minimizing the variance in resistance value of an elastic intermediate transfer belt when cleaning defect occurs. <P>SOLUTION: The image forming apparatus which employs an electrostatic cleaning system for cleaning the intermediate transfer member and has a web member to be brought into contact with the intermediate transfer member after cleaning, includes a control means which detects dirt of the web member to determine the state of cleaning or transfer. When the dirt of the web member is detected to determine that the dirt level of the web is abnormal, the set condition of cleaning or transfer is reset, and feed timing of the web is changed according to the reset conditions of cleaning or transfer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus having an electrostatic copying process, and more particularly to an image forming apparatus provided with a method for controlling a cleaning abnormality that occurs during image formation.

  In recent years, in an image forming apparatus using an electrostatic process, an intermediate transfer belt is widely used because of the need for high-quality images on a wide variety of papers. As the intermediate transfer belt, a resin belt typified by polyimide or the like is generally widely used because of its high image quality, long life, and high stability. Also, as the intermediate transfer belt cleaning device, a blade system as disclosed in Patent Document 1 having a high cleaning capability is widely used in consideration of the surface property of the resin belt and the like.

  On the other hand, recently, the toner has been changed to a smaller particle size and a non-spherical toner shape due to further higher image quality and stabilization of the cleaning ability by the blade method.

  However, in the intermediate transfer belt made of resin, there is a problem of a hollowing out phenomenon that occurs at the time of transfer accompanying a change in toner. When the image is transferred, a large pressure is applied to the image, so that the toner undergoes stress deformation, the cohesive force between the toners increases, and a part of the image is not transferred onto the image carrier. This is a phenomenon that remains, particularly in characters and line images. In the case of a resin belt, since the pressure on the image at the time of transfer is large, this hollowing out is a problem.

  Therefore, in order to eliminate this void, an elastic intermediate transfer belt using an elastic layer as a surface layer has recently become the mainstream instead of the intermediate transfer belt using a resin. It is known that the elastic intermediate transfer belt is soft because the surface layer is elastic, and the pressure acting on the toner at the transfer portion can be reduced. Also, since the secondary transfer section has good adhesion to paper, it not only improves transfer efficiency for general paper, but is also effective for transfer to thick paper and transfer to uneven paper. It is known that there is.

  However, when cleaning the elastic intermediate transfer belt, if the blade method is used, the surface layer is elastic, so the contact load of the cleaning blade against the elastic intermediate transfer belt increases, and the edge of the cleaning blade bites into the belt surface layer. Therefore, problems such as turning over, chattering and squealing of the cleaning blade caused by unstable behavior of the edge of the cleaning blade, causing poor cleaning, and increasing frictional force between the belt and the cleaning blade, There are fears that the image quality may be disturbed due to various adverse effects such as scratches on the surface of the elastic belt and the occurrence of toner fusion.

  Therefore, in order to avoid the above-described adverse effects, an electrostatic fur brush method that has a small contact load with the elastic intermediate transfer member has become common as an elastic intermediate transfer member cleaning method.

  As an electrostatic fur brush method, as in Patent Document 2, a cylindrical member in which conductive fibers are wound around a core metal is brought into contact with a bias applied, and a bias having a polarity opposite to that of toner is applied. Thus, the toner is electrostatically attracted to the fur brush and the toner is removed from the image carrier.

  It is known that the fur brush method that electrostatically adsorbs toner and removes toner from the belt has more restrictions on the amount of toner that can be cleaned and the toner polarity than the blade method that mechanically removes toner. . In the electrostatic fur brush method, after the toner is electrostatically adsorbed to the fur brush, the original effect of the fur brush cannot be obtained unless the toner is further transferred from the fur brush with a flicker or a bias application roller. As the amount of toner adsorbed by the fur brush increases, the cleaning performance decreases, and the amount that can be cleaned is generally inferior to the blade method.

  Further, as described above, since the fur brush method is a method in which toner is adsorbed to the fur brush and cleaned, only toner having a polarity opposite to the bias applied to the fur brush is cleaned.

  However, the transfer residual toner that remains after the toner image on the intermediate transfer belt is transferred to the paper is reversed in polarity (from plus to minus or from minus depending on the bias value applied at the time of transfer). To the plus). The transfer residual toner whose polarity is inverted is the same polarity as the applied bias of the fur brush, and therefore is not attracted by the fur brush and passes.

  The toner that has passed through the fur brush overlaps with the next image, which may cause image defects. For this reason, as disclosed in Patent Document 3, by using two fur brushes and applying biases having different polarities to each other, the bias at the secondary transfer unit, the use environment, the toner deterioration, and the like Thus, the toner can be reliably adsorbed to the fur brush and removed regardless of whether the polarity is positive or negative.

By the way, in the elastic intermediate transfer belt used in the electrophotographic system, the external additive adheres to the surface layer, which causes transfer failure and cleaning failure. This is because the resistance of the surface layer of the elastic intermediate transfer belt fluctuates due to adhesion of the external additive to the surface layer, and the voltage or current set value deviates from a desired value. As disclosed in Patent Document 4, these can be improved by installing a web member or the like for removing deposits adhering to the intermediate transfer belt downstream of the cleaning device.
JP 2001-305878 A Japanese Patent No. 0336442 JP 2002-207403 A Japanese Patent Laid-Open No. 10-149033

  However, when a cleaning failure occurs in a copying machine equipped with a web in the above-described electrophotographic system, a large amount of toner and external additives are deposited on the web disposed downstream of the cleaning device. As a result, the web rubs deposits on the elastic intermediate transfer belt, contrary to its original function, and the resistance value of the elastic intermediate transfer belt fluctuates, causing image defects and the like. There are no particular restrictions on the adhered matter that adheres to the elastic intermediate transfer member as long as it can be attached in practice.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to minimize the fluctuation of the resistance value of the elastic intermediate transfer belt when a cleaning failure occurs in an image forming apparatus provided with a web. An object of the present invention is to provide an image forming apparatus capable of suppressing image defects.

  In order to achieve the above object, an invention according to claim 1 employs an electrostatic cleaning method for cleaning an intermediate transfer member, and includes an image forming apparatus having a web member that comes into contact with the intermediate transfer member after cleaning. It has a control means for detecting dirt and judging the state of cleaning or the state of transfer.

  According to a second aspect of the present invention, in the first aspect of the invention, when the web member is detected to be dirty and the level of the dirty web is determined to be abnormal, the cleaning or transfer setting conditions are reset, and the cleaning or transfer is performed. The web feed timing is changed according to the setting conditions.

  The invention according to claim 3 is characterized in that, in the invention according to claim 1 or 2, when an abnormality occurs in cleaning or transfer, the situation is notified to a service person via a network.

  According to the first aspect of the present invention, when the cleaning state is detected by detecting the wiping history of the web disposed downstream of the cleaning device, and the wiping history is determined to be abnormal, the resistance value of the elastic intermediate transfer belt is determined. Therefore, the normal image forming process is once interrupted. Next, the voltage or current set value of the transfer device and the cleaning device is reset electrostatically. Thereby, it is possible to suppress image defects due to deviations in electrical settings.

  According to the second aspect of the present invention, when the cleaning state is detected by detecting the web wiping history, and the wiping history is determined to be abnormal, the resistance value of the elastic intermediate transfer belt may vary. The normal image forming process is once interrupted. Next, the voltage or current set value of the transfer device and the cleaning device is reset electrostatically. Even if the set value condition is an appropriate value, if the web wiping history is detected as abnormal, the web feed timing is changed. By advancing the web feed timing, the amount of toner and external additives that the web rubs against the elastic intermediate transfer belt is reduced, and the resistance value of the elastic intermediate transfer belt is minimized.

  According to the third aspect of the present invention, when an abnormality occurs in cleaning or transfer, the web feed timing is stopped. This speeds up web consumption. This situation can be promptly communicated to the service person through the network, so that the subsequent response can be promptly promoted.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1>
The present embodiment relates to a tandem type image forming apparatus provided with an image carrier composed of four photoconductors. As shown in FIG. 1, the image forming apparatus according to the present embodiment includes a belt-like elastic intermediate transfer member, that is, an endless elastic intermediate transfer belt 181. The elastic intermediate transfer belt 81 is wound around the driving roller 25, the tension roller 26, and the backup roller 29 as a support. Along the horizontal portion of the elastic intermediate transfer belt 81, four image forming portions Pa, Pb, Pc, and Pd having the same configuration are arranged in series. The configuration of the image forming unit Pa will be described as an example.

  The image forming unit Pa includes a drum-shaped electrophotographic photosensitive member (hereinafter, referred to as “photosensitive drum”) 101a which is an image carrier that is rotatably arranged. Around the photosensitive drum 101a, process devices such as a primary charger 122a, a developing device 123a, and a cleaning device 112a are arranged. The other image forming units Pb, Pc, and Pd have the same configuration as the image forming unit Pa, and are respectively photosensitive drums 101b, 101c, and 101d, primary chargers 122b, 122c, and 122d, and developing units 123b, 123c, and 123d. Cleaning devices 112b, 112c and 112d are provided. These image forming portions Pa, Pb, Pc, and Pd are different in that toner images of respective colors of yellow, magenta, cyan, and black are formed.

  The developing devices 123a to 123d disposed in the image forming units Pa to Pd respectively store yellow toner, magenta toner, cyan toner, and black toner.

  The photosensitive drum 111a is uniformly charged by the primary charger 122a, and an image signal based on the magenta component color of the original is projected from the exposure device 111a onto the photosensitive drum 101a via a polygon mirror or the like to form an electrostatic latent image. The

  Next, yellow toner is supplied from the developing device 123a, and the electrostatic latent image is developed as a yellow toner image. When the toner image arrives at the primary transfer portion T1 where the photosensitive drum 101a and the elastic intermediate transfer belt 181 come into contact with the rotation of the photosensitive drum 101a, a primary transfer device (first transfer means), that is, In the present embodiment, a first transfer bias is applied from the transfer roller 124 a, and the yellow toner image is transferred to the intermediate transfer belt 181. When the elastic intermediate transfer belt 181 carrying the yellow toner image is conveyed to the next image forming portion Pb, it has been formed on the photosensitive drum 101b in the image forming portion Pb by the same method as described above. A magenta toner image is transferred onto the yellow toner image.

  Similarly, as the elastic intermediate transfer belt 181 advances to the image forming portions Pc and Pd along the direction of the arrow, the cyan toner image and the black toner image are superimposed and transferred onto the above-described toner image at each transfer portion T1. Thereafter, by this time, the recording material P sent out from the paper feed cassette 160 reaches the secondary transfer portion T2, and the above four colors are applied by the transfer bias applied to the secondary transfer device (second transfer means) 140. The toner image is transferred onto the recording material P.

  The recording material P to which the toner image has been transferred is conveyed to the fixing unit 211. The fixing unit 211 fixes the toner image on the recording material P by heat and pressure. The transfer residual toner on the photoconductor that has not been completely transferred by the primary transfer member is cleaned by the cleaning device 112, and the transfer residual toner on the intermediate transfer belt 181 that has not been completely transferred by the secondary transfer member is the first cleaning device. 116a and the second cleaning device 116b are used for cleaning. The external additive that adheres to the surface of the elastic intermediate transfer belt 118 and cannot be recovered by the cleaning device is scraped off by the web 125 disposed after the cleaning device and used for the next image formation.

  Next, the configuration of each unit will be sequentially described by taking the image forming unit Pa as an example.

  The photosensitive drum 101a as an image carrier is formed by applying an organic photoconductive layer (OPC) to the outer peripheral surface of an aluminum cylinder. The photosensitive drum 101a is rotatably supported at both ends by flanges, and is driven to rotate counterclockwise in the figure by transmitting a driving force from a drive motor (not shown) to one end. .

  The primary charger 122a is a conductive roller formed in a roller shape. The roller is brought into contact with the surface of the photosensitive drum 101a, and a charging bias voltage is applied by a power source (not shown), whereby the surface of the photosensitive drum 101a. Are uniformly charged to a negative polarity.

  The exposure device 111a is composed of an LED array having a polygon mirror (not shown) attached to the tip thereof, and lighting control is performed according to an image signal by a drive circuit (not shown).

  The developing unit 123a is adjacent to the surface of the toner storage unit (not shown) storing toners of black, cyan, magenta, and yellow having negative charging characteristics, and is rotated by a driving unit (not shown) adjacent to the surface of the photosensitive drum 101a. In addition, the image forming apparatus includes a developing roller that performs development by applying a developing bias voltage from a developing bias power source (not shown). In the toner storage portion, toners of yellow, magenta, cyan, and black are stored in the toner storage portion in order from the upstream side in the conveyance direction of the transfer material.

  Inside an intermediate transfer belt 181 to be described later, transfer rollers 124a, 125b, 125c, and 125d, which are temporary transfer members that face the four photosensitive drums 101a, 101b, 101c, and 101d and abut against the intermediate transfer belt 181, are provided. They are arranged side by side. These transfer rollers are connected to a power supply for transfer bias (not shown), and a positive voltage is applied from the transfer roller. This electric field causes the intermediate transfer member 181 in contact with the photosensitive drum 101 to be in contact with the photosensitive drum. The negative color toner images on 101 are sequentially transferred to form a color image.

  In the present invention, the intermediate transfer belt 181 includes an endless elastic intermediate transfer belt as described above. FIG. 2 is a cross-sectional view of an example of the elastic intermediate transfer belt 181. The elastic intermediate transfer belt 181 is an elastic belt having a three-layer structure including a resin layer 181a, an elastic layer 181b, and a surface layer 181c.

  As the resin material constituting the resin layer 181a, polycarbonate, fluororesin (ETFE, PVDF), polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, Styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer) Styrene-octyl acrylate copolymer and styrene-phenyl acrylate copolymer), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene) -Phenyl methacrylate copolymer, etc.) Styrenic resins (monopolymer or copolymer containing styrene or styrene-substituted product) such as styrene-α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylate ester copolymer, methyl methacrylate resin, methacryl Acid butyl resin, ethyl acrylate resin, butyl acrylate resin, modified acrylic resin (silicone modified acrylic resin, vinyl chloride resin modified acrylic resin, acrylic / urethane resin, etc.), vinyl chloride resin, styrene-vinyl acetate copolymer, chloride Vinyl-vinyl acetate copolymer, rosin modified maleic acid resin, phenol resin, epoxy resin, polyester resin, polyester polyurethane resin, polyethylene, polypropylene, polybutadiene, polyvinylidene chloride, ionomer resin, polyurethane resin, silicon Use one or more selected from the group consisting of resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin and polyvinyl butyral resin, polyamide resin, polyimide resin, modified polyphenylene oxide resin, modified polycarbonate, etc. be able to. However, it is not limited to the above materials.

  The elastic material (elastic material rubber, elastomer) constituting the elastic layer 181b includes butyl rubber, fluorine rubber, acrylic rubber, EPDM, NBR, acrylonitrile-butadiene-styrene rubber natural rubber, isoprene rubber, styrene-butadiene rubber. , Butadiene rubber, Ethylene-propylene rubber, Ethylene-propylene terpolymer, Chloroprene rubber, Chlorosulfonated polyethylene, Chlorinated polyethylene, Urethane rubber, Syndiotactic 1,2-polybutadiene, Epichlorohydrin rubber, Ricone rubber, Fluoro rubber , Polysulfide rubber, polynorbornene rubber, hydrogenated nitrile rubber, thermoplastic elastomer (eg polystyrene, polyolefin, polyvinyl chloride, polyurethane, polyamide, polyurea, polyester Le system, it is possible to use one kind or two kinds or more selected from the group consisting of fluorocarbon resin) or the like. However, it is a matter of course that the material is not limited to the above materials.

  Further, the material of the surface layer 181c is not particularly limited, but a material that increases the secondary transferability by reducing the adhesion force of the toner to the surface of the intermediate transfer belt 181 is required. For example, one kind of resin material such as polyurethane, polyester, epoxy resin, elastic material (elastic material rubber, elastomer), butyl rubber, fluorine rubber, acrylic rubber, EPDM, NBR, acrylonitrile-butadiene-styrene rubber natural rubber, isoprene Using two or more kinds of elastic materials such as rubber, styrene-butadiene rubber, butadiene rubber, ethylene-propylene rubber, ethylene-propylene terpolymer, chloroprene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, and urethane rubber to reduce surface energy. Disperse materials that are small and improve lubricity, such as powders of fluororesin, fluorine compounds, fluorocarbons, titanium dioxide, silicon carbide, etc., one type or two or more types or particles with different particle sizes Can be used.

  A resistance value adjusting conductive agent is added to the resin layer 181a and the elastic layer 181b. The conductive agent for adjusting the resistance value is not particularly limited. For example, carbon black, graphite, metal powder such as aluminum and nickel, tin oxide, titanium oxide, antimony oxide, indium oxide, potassium titanate, antimony oxide-tin oxide Conductive metal oxides such as composite oxide (ATO) and indium oxide-tin oxide composite oxide (ITO), and conductive metal oxide covered with insulating fine particles such as barium sulfate, magnesium silicate, and calcium carbonate. Things can be used. It is not limited to the conductive agent.

  Examples of the method for manufacturing the intermediate transfer belt 181 include a centrifugal molding method in which a material is poured into a rotating cylindrical mold to form a belt, a spray coating method in which a thin film is formed on the surface, and a cylindrical mold as a material solution. There are a dipping method in which it is soaked in the mold, a casting method in which it is poured into the inner mold and the outer mold, and a method in which the compound is wound around a cylindrical mold and vulcanized and polished. A belt can be manufactured by combining the production methods.

  The color image carried on the intermediate transfer belt 181 in the primary transfer portion is further transferred to the transfer material P by the secondary transfer roller 140 which is in contact with the intermediate transfer belt 181 and is a secondary transfer member. The secondary transfer roller is connected to a transfer bias power source (not shown), and a positive voltage is applied from the transfer roller. Due to this electric field, the intermediate transfer belt is applied to the transfer material P in contact with the intermediate transfer belt 181. The negative polarity toner image on 181 is sequentially transferred to form a color image.

  Next, the details of the first cleaning unit 116 for residual toner remaining on the intermediate transfer belt 181 after the secondary transfer will be described.

As shown in FIG. 3, the electrostatic brush cleaning device includes a device housing 117 disposed in the vicinity of the intermediate transfer belt 181 and carbon having a resistance value of 10 MΩ and a fiber thickness of 6 denier provided inside the device housing 2. It is formed by a conductive fur brush 118 formed by flocking dispersed nylon fibers 3 on a metal roller at a density of 500,000 / inch ² and a metal roller 119 made of aluminum with a hard anodized surface. The first and second intermediate transfer body first cleaning members 161a are configured by a cleaning blade 120 disposed in contact with the conductive brush roller, and a cleaning member having this configuration is arranged in parallel on the intermediate transfer belt. , 161b constitutes a main part thereof.

  The conductive fur brush 118 is placed in sliding contact with the intermediate transfer belt 181 while maintaining an intrusion amount of about 1.0 mm, and is rotated in the direction of the arrow at a speed of 50 mm / second by a drive motor (not shown). Is formed. The metal roller is arranged so as to keep an intrusion amount of about 1.0 mm with respect to the conductive fur brush, and is arranged so as to be rotated in the direction of the arrow at a speed equivalent to that of the conductive fur brush. The cleaning blade 120 that comes into contact with the metal roller is made of urethane rubber, and is disposed so as to maintain an intrusion amount of 1.0 mm with respect to the metal roller.

  A DC voltage of −500 V (with respect to ground, the same applies hereinafter) is applied to a metal roller of the cleaning member 116 a located upstream with respect to the rotation direction of the intermediate transfer belt by a DC power source (not shown). A DC voltage of +500 V is applied to the metal roller of the cleaning member 116b located downstream of the intermediate transfer belt rotation direction. By applying a voltage to the metal roller, a potential difference is generated between the roller and the fur brush, and (+) toner in the transfer residual toner on the intermediate transfer belt 181 is attracted and transferred to the fur brush 118 side. The adsorbed and removed toner is further transferred from the fur brush 118 to the metal roller 119 due to a potential difference, and scraped off by the cleaning blade 120.

  Even if the transfer residual toner on the intermediate transfer belt 181 is cleaned by the cleaning member 116b, the toner having no polarity or the toner having the polarity (−) remains on the intermediate transfer belt 181. These toners are charged (−) by a (−) bias applied to the fur brush. This is considered to be charged by charge injection or discharge.

  Then, cleaning is performed by applying a (+) bias to the second cleaning member 116b disposed on the downstream side, whereby the toner can be removed. The removed toner is transferred from the fur brush 118b to the metal roller 119b due to the potential difference, and scraped off by the cleaning blade 120b, whereby the transfer residual toner remaining on the intermediate transfer belt 181 can be removed.

  As the member of the web 125 disposed after the cleaning device, one type or two or more types selected from polyester, acrylic, vinylon, water-soluble vinylon, rayon, nylon, polypropylene, cotton and the like can be used. However, it is not limited to the above materials.

  The web 125 is disposed downstream (near) the cleaning device, and is in contact with the surface layer of the elastic intermediate transfer belt 118 with a total pressure of 2.0 kg. The external additive released from the toner is rubbed and adhered to the surface of the elastic intermediate transfer belt at a portion where pressure is applied, such as a transfer portion. Since these cannot be recovered by the cleaning device, they are mechanically recovered by the web 125.

  However, if the same surface of the web 125 is used for a long time, the web 125 exceeds the capacity for collecting the deposit, and conversely, the deposit is rubbed against the surface of the elastic intermediate transfer belt 118. It is necessary to take up a certain amount of the web 125 and renew the contact surface with the elastic intermediate transfer 118 belt. In this case, the winding timing and amount of the web 125 are set to 5 mm for every 100 sheets of A4 paper. As a result, deposits adhered to the surface of the elastic intermediate transfer belt 118 can be satisfactorily removed.

  A sensor 126 that senses the wiping trace of the web 125 is a CDD, and senses the wiping trace of the wiping surface in accordance with the winding timing of the web. The sensing result is transmitted to the host computer using the equipped communication means.

  In the present embodiment, the flow is as shown in FIG. This will be described in detail below.

  The copying machine according to the present embodiment is equipped with a sequence for determining an applied voltage to satisfy a set current value for each of the primary transfer unit, the secondary transfer unit, and the cleaning unit (first cleaning and second cleaning). .

  In the image forming apparatus, when the web is sensed by the sensor 126 and the sensing result is abnormal (FIG. 5), the normal image forming process is interrupted, and the web is an image of A41 sheets during the normal image forming process. Feed 5 mm every time required for formation. In the present embodiment, the time is 1 second. At this time, the applied voltage setting sequence for the primary transfer unit, the secondary transfer unit, the first cleaning unit, and the second cleaning unit is performed.

  After the end of the sequence, the web feed timing remains at 5 mm per second, the normal image sequence mode is entered, and after confirming that the sensor sensing result has returned to normal, the web feed timing is returned to normal.

  By performing the above-described series of control, it is possible to minimize the resistance value fluctuation of the elastic intermediate transfer belt and to suppress image defects. The series of process contents is transmitted to the host computer through communication means provided in the copying machine. As a result, the service person can immediately know that the remaining amount of the web has decreased, and can respond quickly.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIG. Note that the image forming apparatus of the present embodiment has a configuration substantially similar to that of the first embodiment.

  In the present embodiment, when the web 126 is sensed by the sensor 126 and the sensing result is abnormal (FIG. 5), the normal image forming process is interrupted, and the web is an image of A41 sheets during the normal image forming process. Feed 5 mm every time required for formation. In the present embodiment, the time is 1 second. At this time, the applied voltage setting sequence for the primary transfer unit, the secondary transfer unit, the first cleaning unit, and the second cleaning unit is performed. After the end of the sequence, the web feed timing remains at 5 mm per second, and the normal image sequence mode is entered.

  However, if the sensing result of the sensor remains abnormal, a degeneration mode is entered in which the productivity of the copier is reduced to 1/3. At this time, the web feed timing is changed to 5 mm in 3 seconds (time required for image formation for 41 sheets of A), and the abnormal state is transmitted to the host computer by the communication means equipped in the copying machine, to the service person. Notify abnormal status. As a result, it is possible to minimize fluctuations in the resistance value of the elastic intermediate transfer belt and to suppress image defects. In addition, the service person can immediately know that there is an abnormality in the copying machine and the remaining amount of the web is low, and can respond quickly.

1 is a simplified cross-sectional view of an image forming apparatus according to Embodiment 1 of the present invention. FIG. 3 is a simplified cross-sectional view showing a cross section of an intermediate transfer belt according to Embodiments 1 and 2 of the present invention. FIG. 3 is a simplified cross-sectional view showing an intermediate transfer belt cleaning unit according to Embodiments 1 and 2 of the present invention. It is a simplified diagram of a control flow according to Embodiments 1 and 2 of the present invention. It is a simplified diagram of the diagnostic criteria according to Embodiments 1 and 2 of the present invention.

Explanation of symbols

1a to 1d Photosensitive drum (image carrier)
24a to 24d Primary transfer portion (first transfer means)
25 Drive roller (support)
26 Tension roller (support)
40 Secondary transfer section (second transfer means)
116a, 116b Intermediate transfer member cleaning device 125 Web 126 Web dirt detection sensor 181 Elastic intermediate transfer belt

Claims (3)

In an image forming apparatus that employs an electrostatic cleaning method for cleaning an intermediate transfer member and has a web member that comes into contact with the intermediate transfer member after cleaning,
An image forming apparatus comprising control means for detecting a stain on a web member and determining a cleaning state or a transfer state.   When web dirt is detected and the web dirt level is determined to be abnormal, the cleaning or transfer setting conditions are reset, and the web feed timing is changed according to the cleaning or transfer setting conditions. The image forming apparatus according to claim 1.   3. The image forming apparatus according to claim 1, wherein when an abnormality occurs in cleaning or transfer, the situation is notified to a service person via a network.

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