JP2016136188A - Cleaning device, image forming apparatus, voltage setting method, and image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning device, an image forming apparatus, a voltage setting method, and an image forming system that can prevent a complicated control of changing a voltage setting value of a voltage to be applied to the cleaning device.SOLUTION: A cleaning device 100 comprises: three or more cleaning members 101, 104, 107 that remove toner on a cleaning target body 2; a plurality of power sources 130a, 132a, 134a that apply a voltage according to a voltage setting value in voltage setting value storage means; current detection means 132b, 134b that detect the amount of a current flowing at contact points of the cleaning members and the cleaning target body; and voltage setting value changing means 200 that changes the voltage setting value on the basis of the amount of the current. While at least one of the plurality of power sources outputs a constant voltage and all the rest of the power sources simultaneously apply a voltage to the cleaning members, the cleaning device changes the voltage setting value of each of the power sources on the basis of a result of detection of the amount of a current flowing at the contact points of the cleaning target body and the cleaning members to which a voltage is applied from the power sources.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cleaning device, an image forming apparatus, a voltage setting method, and an image forming system.

  As an intermediate transfer belt cleaning device that removes transfer residual toner on an intermediate transfer belt in an intermediate transfer type image forming apparatus, a cleaning device that uses a plurality of cleaning members to remove toner using electrostatic force is employed. Are known.

  For example, the image forming apparatus described in Patent Document 1 is provided with a cleaning device in which cleaning brush rollers as three cleaning members are sequentially arranged in the rotation direction of the intermediate transfer belt. In addition, a power source that outputs a voltage to be applied to each cleaning member by constant voltage control is provided corresponding to each cleaning member. In this cleaning device, a voltage according to a voltage setting value in the storage unit is applied from each constant voltage power source to each of the three cleaning brush rollers. As a result, the toner charged to a polarity opposite to the applied voltage is attracted to the cleaning member by an electrostatic force and removed from the intermediate transfer belt.

  In the cleaning device described in Patent Document 1, a voltage is simultaneously applied to each cleaning brush roller to detect the amount of current flowing through the contact portion between each cleaning brush roller and the intermediate transfer belt. Then, the voltage setting value stored in the setting value storage means is changed so that the current amount becomes the target current value.

  However, a phenomenon occurs in which each current flowing through the contact portion between each cleaning member and the intermediate transfer belt flows into a contact portion between the cleaning member different from itself and the intermediate transfer belt. Therefore, when three or more cleaning members are arranged side by side, the voltage setting is performed so that the amount of current flowing through the contact portion between each cleaning member and the intermediate transfer belt is detected and the amount of current becomes a target amount of current. In the control for changing the value, there arises a problem that the control becomes complicated.

  In order to solve the above-described problems, the present invention provides three or more cleaning members that electrostatically remove toner on a member to be cleaned, and each of the three or more cleaning members includes a voltage set value storage unit. Based on a plurality of power supplies for applying a voltage according to a voltage setting value, a current detection means for detecting a current amount flowing through a contact portion between the cleaning member and the object to be cleaned, and a current amount detected by the current detection means And a voltage setting value changing means for changing the voltage setting value in the voltage setting value storage means, wherein at least one of the plurality of power supplies is a predetermined for applying to the cleaning member. A first power source for outputting a voltage, and the remaining power source different from the at least one power source among the plurality of power sources is a power source for applying to the cleaning member. Each of the cleaning members to which a voltage is applied from each of the second power supplies in a state where a voltage is simultaneously applied to all of the three or more cleaning members by the plurality of power supplies. The amount of current flowing in each contact location between the object and the object to be cleaned is detected by the current amount detection means, and based on the detection result, the voltage setting value of the voltage output from each second power source is determined for each contact location. The voltage setting value changing unit changes the target current amount so as to flow through.

  As described above, according to the present invention, there is an excellent effect that the control for changing the voltage setting value of the voltage applied to the cleaning member can be suppressed from becoming complicated.

The flowchart of an example of a voltage setting value change process. 1 is a schematic configuration diagram showing an overall configuration of a copier according to an embodiment. FIG. 3 is an enlarged cross-sectional view illustrating a layer configuration of an intermediate transfer belt. FIG. 3 is an enlarged schematic configuration diagram in the vicinity of a secondary transfer belt showing a gradation pattern and an optical sensor. The enlarged schematic diagram which shows the chevron patch transcribe | transferred to a secondary transfer belt. FIG. 6 is a schematic diagram of a toner consumption pattern transferred to a secondary transfer belt. The enlarged block diagram which expands and shows a belt cleaning apparatus and its periphery. The graph which shows the relationship between the voltage applied to a post-cleaning roller, and the number of spots-like image generation. 6 is a timing chart showing the bias applied to the cleaning brush roller and the post cleaning roller and the on / off timing of the bias applied to each recovery roller. The schematic block diagram which shows the power supply part with which a belt cleaning apparatus is provided.

  Hereinafter, an embodiment in which an image forming apparatus according to the present invention is applied to an electrophotographic copying machine which is an intermediate transfer tandem image forming apparatus will be described with reference to the drawings. FIG. 2 is a schematic configuration diagram showing the overall configuration of the copying machine 1 according to the present embodiment. The copying machine 1 has a tandem configuration in which a plurality of photoreceptors 3M, 3C, 3Y, and 3B, which are image carriers as latent image carriers that carry toner images of colors corresponding to color separation, are juxtaposed. . The toner images formed on the photoconductors 3M, 3C, 3Y, and 3B are superimposed and transferred (primary transfer) so as to overlap each other on an intermediate transfer belt 2 as an intermediate transfer body that is a transfer target, and the superimposed toner. The image is collectively transferred (secondary transfer) to a recording sheet as a recording material. In this way, the copying machine 1 can form a multi-color image on the recording paper.

  In FIG. 2, the copying machine 1 has an image forming unit 10 positioned at the center in the vertical direction, a document feeding unit 20 below the image forming unit 10, and a document scanning unit provided with a document table 31 above the image forming unit 10. The parts 30 are arranged respectively. In the image forming unit 10, an intermediate transfer belt 2 having a stretched surface in the horizontal direction is disposed. The image forming unit 10 includes four photosensitive members 3Y, 3C, 3M, and 3B that carry toner images of complementary colors (yellow, cyan, magenta, and black) along the stretched surface of the intermediate transfer belt 2. Are juxtaposed. In the following description, in the case of contents common to all colors, Y, C, M, and B, which are color-coded codes, are omitted as appropriate.

  Each of the photoconductors 3Y, 3C, 3M, and 3B includes a drum that can rotate in the same direction (counterclockwise in FIG. 2). Around that, a charging device 4, a writing device 5, a developing device 6, a primary transfer device, and a drum cleaning device 8 that perform image forming processing in the rotation process are arranged, and constitute an image forming unit 66. . In FIG. 2, for the sake of convenience, the reference numerals of the respective devices are attached to the black photoconductor 3B. The toner images on the photoreceptors 3Y, 3C, 3M, and 3B are sequentially transferred to the intermediate transfer belt 2 by a primary transfer device. The intermediate transfer belt 2 is rotated around a plurality of belt stretching rollers. As the plurality of belt stretching rollers, two belt stretching rollers 2a and 2b constituting a stretching surface facing the photoreceptors 3Y, 3C, 3M, and 3B of the intermediate transfer belt 2 are provided. Further, a secondary transfer counter roller 2c to which a bias having the same polarity as the normal charging polarity of the toner is applied is opposed to the secondary transfer device 9 with the intermediate transfer belt 2 interposed therebetween. Note that the normal charging polarity of the toner here refers to the charging polarity of the toner in the developer in the developing device 6. Although it is negative in the present embodiment, it may be positive depending on the image forming apparatus. Furthermore, a tension roller 2d that applies tension to the intermediate transfer belt 2 is provided.

  The transfer residual toner remaining on the intermediate transfer belt 2 after the secondary transfer is removed by the belt cleaning device 100. The belt cleaning apparatus 100 is an electrostatic cleaning system, and applies a bias to a cleaning roller or a cleaning brush, and electrostatically adsorbs the transfer residual toner adhering to the intermediate transfer belt 2 for cleaning.

  The secondary transfer device 9 includes a secondary transfer belt 9a, and the secondary transfer belt 9a is wound around four secondary transfer belt support rollers. Then, when one of the four secondary transfer belt support rollers is rotationally driven as a drive roller, the secondary transfer belt 9a rotates counterclockwise in FIG. The optical sensor 300 is disposed at a position facing the surface of the secondary transfer belt 9a on the downstream side in the surface movement direction of the secondary transfer belt 9a with respect to the secondary transfer portion where the secondary transfer belt 9a faces the intermediate transfer belt 2. ing. Further, a secondary transfer belt cleaning device 190 that removes foreign matters on the surface of the secondary transfer belt 9a is provided on the downstream side in the surface movement direction of the secondary transfer belt 9a with respect to the position where the optical sensor 300 faces.

  One of the four secondary transfer belt support rollers is applied with a secondary transfer bias having the same polarity as the toner on the belt, with the secondary transfer belt 9a and the intermediate transfer belt 2 sandwiched between the secondary transfer portions. The secondary transfer roller 9b faces the next transfer counter roller 2c. Further, on the left side of the secondary transfer roller 9b, the recording paper carried on the surface of the secondary transfer belt 9a after passing through the secondary transfer portion is transferred to the transport belt 91, and the secondary is separated by the paper separation portion. A separation roller 9c is provided to stretch the transfer belt 9a. A sensor facing roller 9d is provided that stretches the secondary transfer belt 9a at a detection position where the secondary transfer belt 9a of the separation roller 9c faces the optical sensor 300. Further, the secondary transfer belt 9a is stretched across the secondary transfer belt 9a at a position where the cleaning blade of the secondary transfer belt cleaning device 190 contacts the right side of the sensor facing roller 9d and below the secondary transfer roller 9b. A roller 9e is provided.

  The secondary transfer belt 9 a moves on the surface in the same direction as the intermediate transfer belt 2 at the secondary transfer portion that contacts the intermediate transfer belt 2. Although depending on the bias characteristics of the primary transfer device, the secondary transfer roller 9b may be provided with a charging characteristic to electrostatically attract the recording paper. The secondary transfer device 9 transfers the superimposed toner image or the single color toner image on the intermediate transfer belt 2 to the recording sheet in the process of conveying the recording sheet by the secondary transfer belt 9a.

  A recording sheet is fed from the sheet feeding unit 20 to the secondary transfer unit. The paper feed unit 20 is positioned upstream of the plurality of paper feed cassettes 21, the plurality of transport rollers 22 disposed in the transport path of the recording paper fed out from the paper feed cassette 21, and the secondary transfer unit in the paper transport direction. And a registration roller 23. Further, in addition to the conveyance path of the recording paper fed out from the paper feeding cassette 21, the type of recording paper that is not accommodated in the paper feeding cassette 21 can be fed to the paper feeding unit 20 toward the secondary transfer unit. Configuration is provided. As this configuration, a manual feed tray 40 provided so that a part of the wall surface of the image forming unit 10 can be turned upside down and a feeding roller 41 are provided. In the middle of the recording paper conveyance path from the paper feed cassette 21 to the registration roller 23, the recording paper conveyance path fed out from the manual feed tray 40 joins. The registration timing is set by the registration rollers 23 for the recording paper fed from any conveyance path.

  In the writing device 5, writing light is controlled by image information obtained by scanning a document on a document placing table 31 included in the document scanning unit 30 or image information output from a computer. An electrostatic latent image is formed on the photoreceptors 3Y, 3C, 3M, 3B according to the image information. The document scanning unit 30 is provided with a scanner 32 that exposes and scans the document on the document placement table 31, and an automatic document feeder 33 is disposed on the upper surface of the document placement table 31. The automatic document feeder 33 has a configuration capable of reversing the document fed on the document placement table 31, and can perform scanning on each surface of the document. The electrostatic latent images formed on the photoreceptors 3Y, 3C, 3M, and 3B by the writing device 5 are developed and developed by the developing device 6 (indicated by reference numeral 6B for convenience in FIG. 2). The transferred image is primarily transferred to the intermediate transfer belt 2. When the toner images for each color are superimposed and transferred onto the intermediate transfer belt 2, the secondary transfer device 9 performs secondary transfer on the recording paper at once.

  In the copying machine 1 of the embodiment shown in FIG. 2, a conveyance belt 91 is provided between the secondary transfer belt 9 a and the fixing device 11. The conveyor belt 91 is wound around a conveyor belt drive roller 91a and a conveyor belt driven roller 91b, and rotates in the counterclockwise direction in FIG. 2 when the conveyor belt drive roller 91a is driven to rotate. The recording paper that has been secondarily transferred is conveyed leftward in the drawing as the surface of the secondary transfer belt 9a moves, separated from the secondary transfer belt 9a at the position of the separation roller 9c, and transferred to the conveying belt 91. The conveying belt 91 conveys the recording paper delivered from the secondary transfer belt 9 a to the fixing device 11, and the unfixed image carried on the surface of the recording paper reaching the fixing device 11 is fixed by the fixing device 11. The

  The fixing device 11 has a belt fixing structure including a fixing belt heated by a heating roller, and a pressure roller facing and abutting the fixing belt. By providing a contact area between the fixing belt and the pressure roller, that is, a nip area, a heating area for the recording paper can be expanded as compared with the fixing structure of another roller type. The recording sheet that has passed through the fixing device 11 is switched in its transport direction by a transport path switching claw 12 disposed behind the fixing device 11, and is discharged again by the paper discharge tray 50 or the registration roller 23 again. It is sent toward.

  In the copying machine 1 shown in FIG. 2, a primary transfer device as a transfer unit uses primary transfer rollers 7Y, 7C, 7M, and 7B to which a positive polarity transfer bias is applied. The primary transfer rollers 7Y, 7C, 7M, and 7B are pressed by a predetermined pressure against the photoreceptors 3Y, 3C, 3M, and 3B via the intermediate transfer belt 2 by a bearing and an elastic body such as a compression spring. . Further, the primary transfer rollers 7Y, 7C, 7M, and 7B move in the direction of the surface of the intermediate transfer belt by about 1 [mm] to 2 [mm] with respect to the positions facing the center positions of the photoreceptors 3Y, 3C, 3M, and 3B. It rotates in conjunction with the intermediate transfer belt 2 at a position offset to the downstream side. This is to prevent pre-transfer that starts transfer by a transfer bias before the normal transfer position and generates an abnormal image such as an image flow.

The primary transfer rollers 7Y, 7C, 7M, and 7B are configured in such a manner that a rubber material having a medium resistance electric characteristic is wound around a metal core. In Embodiment 1, it is comprised with the foaming rubber of medium resistance, The volume resistivity is 10 < ⁶ > [ohm * cm] -10 < ¹⁰ > [ohm * cm], Preferably it is 10 < ⁷ > [ohm * cm] -10 < ⁹ > [. Ω · cm]. The material is not limited to foam rubber, and medium resistance solid rubber can be used as well. A primary transfer voltage having a positive polarity is applied to the primary transfer rollers 7Y, 7C, 7M, and 7B by a constant current controlled power source, and the current setting value (setting value of the primary transfer current) is approximately 10 [μA]. It is controlled in the range of ˜40 [μA]. In this way, by applying the primary transfer voltage to the primary transfer rollers 7Y, 7C, 7M, and 7B, the primary transfer electric field is applied to the primary transfer portion between each of the photoreceptors 3Y, 3C, 3M, and 3B and the intermediate transfer belt 2. Is formed. This primary transfer electric field is a primary transfer electric field in a direction in which the toner (negative polarity) on each of the photoreceptors 3Y, 3C, 3M, and 3B is drawn toward the intermediate transfer belt 2 side.

  On the other hand, a secondary transfer voltage having a negative polarity is applied to the secondary transfer counter roller 2c by a power source controlled at a constant current. Thus, in the configuration in which the secondary transfer voltage is applied to the secondary transfer counter roller 2c, the secondary transfer roller 9b is electrically grounded. By facing the secondary transfer roller 9b connected to the ground, a secondary transfer electric field is formed in the secondary transfer portion in the direction in which the toner (negative polarity) on the intermediate transfer belt 2 is pushed out to the recording paper side. .

  The intermediate transfer belt 2 used in Embodiment 1 is a three-layer belt provided with an elastic layer of 100 [μm] to 500 [μm] on a base layer of 50 [μm] to 100 [μm] and further having a surface layer. It is configured. Specific examples of the base layer include carbon dispersion in materials such as PI (polyimide), PAI (polyamideimide), PC (polycarbonate), ETFE (ethylene-tetrafluoroethylene), PVDF (polyvinylidene fluoride), and PPS (polyphenylene sulfide). Alternatively, there is one constituted by a medium resistance resin whose resistance is adjusted by blending an ionic conductive agent. Specific examples of the elastic layer include a rubber material such as urethane, NBR, CR, and the like, which includes a material whose resistance is adjusted by carbon dispersion or ionic conductive agent blending. As a specific example of the surface layer, a coating of a fluorine-based rubber or resin having a thickness of about 1 [μm] to 10 [μm] (or a hybrid material thereof) is applied to the surface of the elastic layer. There is what I did.

The intermediate transfer belt 2 used in Embodiment 1 has a volume resistivity of 10 ⁶ [Ω · cm] to 10 ¹⁰ [Ω · cm], preferably 10 ⁸ [Ω · cm] to 10 ¹⁰ [Ω · cm]. Range. The surface resistivity is in the range of 10 ⁶ [Ω / □] to 10 ¹² [Ω / □], preferably 10 ⁸ [Ω / □] to 10 ¹² [Ω / □]. Further, the Young's modulus (longitudinal elastic modulus) of the base layer is desirably 3000 [MPa] or more, and sufficient mechanical strength is required to withstand elongation, bending, wrinkle, and waviness due to driving. By using the intermediate transfer belt 2 having such elasticity, the recording paper such as a paper having a low density of paper fibers or a so-called embossed paper having an unevenness of 20 [μm] to 30 [μm] on the surface is recorded. Also in the paper, the elastic layer follows the recess. For this reason, a solid filling improvement effect that the toner transfer property to the concave portion of the recording paper is improved is known.

  The secondary transfer belt 9a used in this embodiment is a single-layer belt. Specific examples include carbon dispersion in materials such as PI (polyimide), PAI (polyamideimide), PC (polycarbonate), ETFE (ethylene-tetrafluoroethylene), PVDF (polyvinylidene fluoride), and PPS (polyphenylene sulfide). Alternatively, a medium resistance resin single layer whose resistance is adjusted by blending an ionic conductive agent can be used. Further, a belt having a surface layer slightly higher in resistance than the volume resistivity of the belt layer itself may be provided only on the surface side of the secondary transfer belt 9a having a single layer structure. In this case, the surface layer thickness is preferably about 1 [μm] to 10 [μm].

  In the image quality adjustment control of the image forming apparatus according to the embodiment, a test pattern is created, and image density control and position shift control are performed based on the result of detecting the image density and image forming position of the test pattern. In the image density control, for example, a toner adhesion amount (image density) of a density control pattern (image quality adjustment pattern) obtained by developing a predetermined pattern latent image is detected. Then, in accordance with the detection result of the toner adhesion amount, set values such as the toner concentration in the developer in the developing device, the writing conditions (exposure power, etc.) of the writing device 5, the charging bias and the developing bias are changed. In the positional deviation control, for example, the latent image writing timing of each color toner image is adjusted by the detection timing of the positional deviation control pattern (image quality adjustment pattern).

  Such image quality adjustment patterns are detected on the photosensitive member between the development area and the primary transfer portion, or on the intermediate transfer belt after the primary transfer of the density control pattern. Can be mentioned. However, when the diameter of the photoconductor is small, it is difficult to detect it on the photoconductor due to the installation space of the image density detection sensor. Therefore, it is preferable to detect it on the intermediate transfer belt. On the other hand, with respect to the positional deviation control pattern, it is necessary to observe the positional deviation between the color toner images due to the variation in the distance between the photoconductors or the positional deviation caused by the writing timing of each color latent image. Therefore, detection on the surface moving body carrying the toner image after the intermediate transfer belt is essential. In the first embodiment, both the density control pattern and the positional deviation control pattern are detected on the secondary transfer belt 9a.

  Conventionally, many medium and low-speed image forming apparatuses have a secondary transfer member that forms a secondary transfer electric field between the secondary transfer counter roller 2c and the intermediate transfer belt 2 at the secondary transfer portion. In general, a roller-shaped member having a small diameter is used instead of a belt-shaped member. In the configuration used for such a roller-shaped member secondary transfer member, it is difficult to detect the image quality adjustment pattern on the surface of the secondary transfer member. In the embodiment, as shown in FIG. 2, if the apparatus includes a secondary transfer belt 9a as a secondary transfer member, the image quality adjustment pattern can be detected on the surface of the secondary transfer member.

  Further, the secondary transfer member is not limited to a belt shape, and may be configured to use a roller having a large diameter. However, in the roller shape, since the detection position of the optical sensor 300 is curved, it is necessary to increase the diameter of the roller, which is disadvantageous in terms of space saving. On the other hand, by using a belt shape like the secondary transfer belt 9a, the degree of freedom can be improved by the layout configuration. In addition, since the belt-like shape is relatively easy to have a configuration in which the detection position of the optical sensor 300 is a flat surface, detection accuracy can be improved. In general, the image density of the image quality adjustment pattern is detected on the intermediate transfer belt 2, but in this embodiment, it is detected on the surface of the secondary transfer belt 9a in order to reduce the cleaning load of the elastic intermediate transfer belt. Adopt the configuration to do.

  As a limitation of the conventional intermediate transfer belt 2, in order to form an image on various recording media, there is surface followability at the secondary transfer portion with respect to the surface of the recording medium having different surface properties. As surface followability, in recent years, images are often formed on various recording media using full-color electrophotography. And as a recording medium, not only normal smooth paper but also high slip smoothness such as coated paper, rough surface such as recycled paper, embossed paper, Japanese paper and kraft paper Are increasingly being used. The followability of the surface of the intermediate transfer belt 2 at the secondary transfer portion for various recording media having different surface properties is important. If this followability is poor, the toner image transferred onto the recording medium has uneven density and color tone.

  An elastic intermediate transfer belt can be given as an example of the intermediate transfer belt 2 having such followability to various recording media. FIG. 3 is an enlarged cross-sectional view showing the layer configuration of the intermediate transfer belt 2. In the intermediate transfer belt 2 shown in FIG. 3, a flexible elastic layer 212 is laminated on a rigid base layer 211 that can be relatively bent, and fine particles are laminated on the outermost surface as a surface layer 213.

  First, the base layer 211 will be described. Examples of the constituent material of the base layer 211 include a resin material containing a filler (or additive) for adjusting electric resistance, a so-called electric resistance adjusting material. As the resin material used for the base layer 211, for example, a fluorine-based resin such as PVDF or ETFE, a polyimide resin, or a polyamide-imide resin is preferable from the viewpoint of flame retardancy. In particular, a polyimide resin or a polyamide-imide resin is particularly preferable from the viewpoint of mechanical strength (high elasticity) and heat resistance. Examples of the electric resistance adjusting material contained in the resin material of the base layer 211 include metal oxide, carbon black, an ionic conductive agent, and a conductive polymer material.

  Next, the elastic layer 212 laminated on the base layer 211 will be described. A rubber elastic layer can be used as the elastic layer 212, and an acrylic rubber can be used as a specific example. As this acrylic rubber, what is marketed now can be used, and it is not specifically limited. However, among the various crosslinking systems (epoxy groups, active chlorine groups, carboxyl groups) of acrylic rubber, the carboxyl group crosslinking system is excellent in rubber properties (especially compression set) and processability, so select the carboxyl group crosslinking system. It is preferable to do.

  Next, the surface layer 213 made of spherical resin fine particles formed on the elastic layer 212 will be described. The material of the fine particles used for the spherical resin fine particles is not particularly limited, and examples thereof include the following. That is, spherical resin fine particles (hereinafter also simply referred to as “resin fine particles”) mainly composed of a resin such as an acrylic resin, a melamine resin, a polyamide resin, a polyester resin, a silicone resin, or a fluororesin. Further, the surface of fine particles made of these resin materials may be subjected to a surface treatment with a different material.

  Further, the resin fine particles referred to herein include a rubber material. A structure in which the surface of spherical resin fine particles made of a rubber material is coated with a hard resin is also applicable. The shape of the resin fine particles may be hollow or porous. Of the above-described materials, silicone resin fine particles are most preferable as a resin having a high function capable of imparting releasability and abrasion resistance to toner.

  The resin fine particles to be used are preferably fine particles produced in a spherical shape by a polymerization method or the like, and those closer to a true sphere are more preferable. The particle size is preferably monodispersed with a volume average particle size of 0.5 [μm] to 5 [μm] and a sharp distribution. When the average particle size is less than 0.5 [μm], the aggregation between the fine particles is remarkable, and thus it is difficult to uniformly apply to the surface of the acrylic rubber elastic layer. On the other hand, when the average particle diameter exceeds 5 [μm], the unevenness of the belt surface after the fine particle application becomes large, and when used as the intermediate transfer belt 2, a cleaning failure occurs during cleaning with the belt cleaning device 100.

The elastic layer 212 has a Martens hardness of 0.2 [N / mm ² ] to 0.8 [N / mm ² ] when pressed into 10 [μm], and the surface layer 213 provided on the surface of the elastic layer 212 However, they are arranged in the plane direction with independent spherical resin particles and are formed in a uniform uneven shape. In such an intermediate transfer belt 2, good followability to the surface of various recording media in the secondary transfer portion can be obtained while ensuring the releasability with respect to the toner by the surface layer 213. Moreover, as the elastic layer 212, good flame retardancy can be obtained while obtaining good followability by using a flame retardant acrylic rubber elastic layer showing VTM-0 in the UL94VTM combustion test. Specific examples of the base layer 211, the elastic layer 212, and the surface layer 213 of the intermediate transfer belt 2 can be those described in Patent Document 1, but are not limited thereto.

  In the case of the intermediate transfer belt 2 having the elastic layer 212 as shown in FIG. 3, the unevenness of the color tone and the unevenness of the color tone can be suppressed for various recording media by the surface following the rough textured paper. Good image formation can be performed. However, the rubber material forming the elastic layer 212 generally has a poor releasability with respect to the toner, and the secondary transfer rate and the cleaning properties are poor unless a surface layer made of another material having a good releasability with respect to the toner is provided. It is difficult to make it practical. As an intermediate transfer belt having a conventional elastic layer, there is one in which a coating layer is provided on the surface of the elastic layer. Specifically, a belt having a coating layer provided on the surface of the elastic layer can be prepared by applying a liquid as a material for the coating layer to the surface of the elastic layer and drying the coating. However, the material used for the coating layer cannot be deformed following the deformation that the rubber material used for the elastic layer expands and contracts over time. Cracks occur. When cracks occur, the transferability and cleaning properties of the toner attached to the cracked portion deteriorate.

  On the other hand, in the intermediate transfer belt 2 shown in FIG. 3, the surface layer 213 has a configuration in which resin fine particles are spread on the surface of the elastic layer 212. For this reason, when the surface of the elastic layer 212 is deformed so as to extend, the adjacent resin fine particles are displaced so as to open, and when the surface of the elastic layer 212 is deformed so as to contract, the space between the adjacent resin fine particles is Displace to clog. Even if the rubber material used for the elastic layer 212 is deformed, only the positional relationship between the resin fine particles is displaced, and cracks and the like do not occur. For this reason, it is possible to maintain the releasability with respect to the toner stable over time, and to improve the transferability and cleaning properties of the toner. However, it is difficult to ensure the cleaning property in the combination of the small particle size polymerized toner and the elastic intermediate transfer belt, which are used for improving the image quality in recent years. Therefore, when the intermediate transfer belt 2 shown in FIG. 3 is used, the correction pattern formed on the intermediate transfer belt 2 is transferred to the secondary transfer belt 9a as in the embodiment, and the toner adhesion amount is measured by the optical sensor 300. It is desirable to detect.

  As shown in FIG. 4, the optical sensor unit provided in the copying machine 1 includes an optical sensor 300Y, an optical sensor 300C, an optical sensor 300M, and an optical sensor 300B arranged in the width direction of the secondary transfer belt 9a. Each of these optical sensors 300 includes a reflection type photosensor, and reflects light emitted from the light emitting element by the toner image on the front surface of the secondary transfer belt 9a or the belt, and detects the amount of reflected light by the light receiving element. . The control unit 200 detects the toner image on the secondary transfer belt 9a based on the output voltage value from the optical sensor 300, or detects the image density (toner adhesion amount per unit area). Can do.

  In the copying machine 1, image density control for optimizing the image density of each color is executed when the power is turned on or whenever a predetermined number of prints are performed. In the image density control, first, as shown in FIG. 4, the gradation patterns Sy, Sc, Sm, and Sb of each color are automatically set at positions on the secondary transfer belt 9a facing the optical sensors 300Y, 300C, 300M, and 300B. Form. The gradation pattern of each color is composed of 10 toner patches having an area of 2 [cm] × 2 [cm] having different image densities. Unlike the uniform drum charging potential in the printing process, the charging potential of the photoreceptors 3Y, 3C, 3M, and 3B when the gradation patterns Sy, Sc, Sm, and Sb of each color are created is gradually increased. To do. Then, while forming a plurality of patch electrostatic latent images for forming a gradation pattern image on the photoreceptors 3Y, 3C, 3M, and 3B by scanning with laser light, they are used for Y, C, M, and B, respectively. Development is performed by the developing devices 6Y, 6C, 6M, and 6B. During this development, the value of the developing bias applied to the developing rollers for Y, C, M, and B is gradually increased.

By such development, gradation pattern images of Y, C, M, and B are formed on the photoreceptors 3Y, 3C, 3M, and 3B. These are transferred via the intermediate transfer belt 2 so as to be arranged at predetermined intervals in the main scanning direction of the secondary transfer belt 9a. At this time, the toner adhesion amount of the toner patch in the gradation pattern of each color is about 0.1 [mg / cm ² ] at the minimum and 0.55 [mg / cm ² ] at the maximum, and the toner Q / d distribution When measured, it is almost aligned with the regular charging polarity. Each toner pattern (Sy, Sc, Sm, Sb) formed on the secondary transfer belt 9a passes through the position facing the optical sensors 300Y, 300C, 300M, 300B as the secondary transfer belt 9a moves endlessly. To do. At this time, the optical sensors 300Y, 300C, 300M, and 300B receive an amount of light corresponding to the toner adhesion amount per unit area with respect to the toner patch of each gradation pattern.

  Next, from the output voltages of the optical sensors 300Y, 300C, 300M, and 300B when each color toner patch is detected and the adhesion amount conversion algorithm, the adhesion amount of each color toner pattern in each toner patch is calculated, and the calculated adhesion is calculated. Adjust the imaging conditions based on the amount. Specifically, a function (y = ax + b) indicating a straight line graph is calculated by regression analysis based on the result of detecting the toner adhesion amount on the toner patch and the development potential when each toner patch is imaged. Then, an appropriate development bias value is calculated by substituting the target value of image density into this function, and development bias values for Y, C, M, and B are specified. The memory stores an image forming condition data table in which several tens of development bias values and appropriate drum charging potentials individually corresponding to the values are associated in advance. For each of the image forming units 66Y, 66C, 66M, and 66B, a developing bias value closest to the specified developing bias value is selected from the image forming condition table, and the drum charging potential associated therewith is specified.

The copying machine 1 also performs color misregistration correction processing when the power is turned on or whenever a predetermined number of prints are performed. In this color misregistration correction process, Y, C, M, and B color toners called chevron patches PV as shown in FIG. 5 are respectively provided at one end and the other end in the width direction of the secondary transfer belt 9a. An image for color misregistration detection composed of an image is formed. As shown in FIG. 5, the chevron patch PV has a predetermined pitch in the belt moving direction, which is the sub-scanning direction, with the toner images of Y, C, M, and B being inclined by about 45 [°] from the main scanning direction. Is a line pattern group arranged in. The amount of the chevron patch PV attached is about 0.3 [mg / cm ² ].

  Then, by detecting each color toner image in the chevron patch PV, the position in the main scanning direction (photoconductor axial direction), the position in the sub-scanning direction (belt moving direction), the magnification error in the main scanning direction in each color toner image, Each skew from the main scanning direction is detected. The main scanning direction here refers to the direction in which the laser light is phased on the surface of the photosensitive member as it is reflected by the polygon mirror. For such Y, C, M toner images in the chevron patch PV, the detection time difference from the B toner image is read by the optical sensors 300Y, 300C, 300M, 300B. In the drawing, the vertical direction of the paper surface corresponds to the main scanning direction, and after the Y, C, M, and B toner images are arranged in order from the left, the postures are different from those of B, M, and C by 90 [°]. , Y toner images are further arranged.

  Based on the difference between the actual measurement value and the theoretical value for the detection time differences tyb, tcb, and tmb from the reference color B, the amount of misregistration of each color toner image in the sub-scanning direction, that is, the amount of registration misregistration is obtained. Then, based on the amount of registration deviation, the optical writing start timing on the photosensitive member 3 is corrected every other polygon mirror of the writing device 5, that is, one scanning line pitch as one unit, and the registration deviation of each color toner image is corrected. Reduce. Further, the inclination (skew) of each color toner image from the main scanning direction is obtained based on the difference in the amount of deviation in the sub-scanning direction between both ends of the belt. Based on the result, surface tilt correction of the optical system reflection mirror is performed to reduce skew of each color toner image.

  As described above, the color misregistration correction process is a process that corrects the optical writing start timing and surface tilt based on the detection timing of each toner image in the chevron patch PV to reduce registration deviation and skew deviation. By such a color misregistration correction process, it is possible to suppress the occurrence of color misregistration of an image due to a shift in the formation position of each color toner image with respect to the secondary transfer belt 9a with time.

  Further, if the image forming operation with a low image area continues, the amount of old toner that stays in the developing device 6 for a long time increases, so that the toner charging characteristics deteriorate and the image quality deteriorates when used for image formation (deterioration of developing ability). , Transferability decline). In order to prevent such old toner from staying in the developing device 6, the toner is discharged to a non-image area of the photoreceptor 3 at a fixed timing, and new toner is supplied to the developing device in which the toner density has been lowered after the discharging. Has a refresh mode for refreshing. The control unit 200 stores the toner consumption amount of each developing device 6Y, 6C, 6M, 6B and the operation time of each developing device 6Y, 6C, 6M, 6B. Then, at a predetermined timing, each of the developing devices 6Y, 6C, 6M, and 6B is checked whether or not the toner consumption amount is equal to or less than a threshold with respect to the operation time of each developing device 6Y, 6C, 6M, and 6B. . Then, the refresh mode is executed for the developing device 6 below the threshold. When the refresh mode is executed, a toner consumption pattern is created in the non-image forming area corresponding to the space between the sheets of the photoreceptor 3 and transferred to the secondary transfer belt 9a (FIG. 6).

  The adhesion amount of the toner consumption pattern is determined based on the toner consumption amount with respect to the operation time of the developing device 6 for a predetermined period. Conventionally, a halftone image has been created in consideration of the cleaning load. However, in the present embodiment, a solid image is used. This is because the transfer rate of the halftone image from the intermediate transfer belt 2 to the secondary transfer belt 9a is low. In the present embodiment, the size of this toner consumption pattern is 330 [mm] in the main scanning direction. Then, the toner patterns of the respective colors are formed on the secondary transfer belt 9a by superimposing two colors in the order of Y to C or M to B as shown below.

-Maximum sub-scanning direction length of each color: 15 [mm]
-Maximum length of each color in the main scanning direction: 330 [mm]
The length of the toner pattern in the sub-scanning direction is determined from the image forming history in the normal image forming operation. Therefore, the length of the Y, C, M, and B toner patterns in the sub-scanning direction is not always a constant length such as 15 [mm], but the length of the toner pattern in the sub-scanning direction independently for each color. The thickness is variable, for example, from 0 [mm] to 15 [mm].

  In the copying machine 1, the contact state between the photoconductor 3 and the intermediate transfer belt 2 is different between a monochrome mode for forming a monochrome image and a color mode for forming a color image. Specifically, of the four primary transfer rollers 7Y, 7C, 7M, and 7B in the transfer unit, the black primary transfer roller 7B is a dedicated bracket separately from the other primary transfer rollers 7Y, 7C, and 7M. I support it. The three primary transfer rollers 7Y, 7C, and 7M for Y, C, and M are supported by a common moving bracket. The moving bracket can be moved in a direction approaching the Y, C, and M photoconductors 3Y, 3C, and 3M and a direction away from the photoconductors 3Y, 3C, and 3M by driving a solenoid. When the moving bracket is moved away from the photoconductors 3Y, 3C, 3M, the tension posture of the intermediate transfer belt 2 changes, and the intermediate transfer belt 2 has three Y, C, M photoconductors 3Y, 3C. , 3M away. However, the B photoconductor 3B and the intermediate transfer belt 2 remain in contact with each other. In the monochrome mode, the image forming operation is performed in a state where only the B photoconductor 3B is in contact with the intermediate transfer belt 2 in this manner.

  When the moving bracket is moved in the direction approaching the three photoconductors 3Y, 3C, and 3M, the tension posture of the intermediate transfer belt 2 changes and has been separated from the three photoconductors 3Y, 3C, and 3M until then. Further, the intermediate transfer belt 2 comes into contact with the three photoconductors 3Y, 3C, and 3M. At this time, the B photoconductor 3B and the intermediate transfer belt 2 remain in contact with each other. In the color mode, the image forming operation is performed in a state where all the four photoconductors 3Y, 3C, 3M, and 3B are in contact with the intermediate transfer belt 2 as described above. In such a configuration, the moving bracket, the solenoid described above, and the like function as contact / separation means for contacting / separating the photoreceptor 3 and the intermediate transfer belt 2.

  For the photoreceptors 3Y, 3C, 3M, and 3B after the Y, C, M, and B toner images are primarily transferred to the intermediate transfer belt 2, the transfer residual toner is cleaned by the drum cleaning devices 8Y, 8C, 8M, and 8B. Apply. Then, after neutralizing with a static elimination lamp, it charges uniformly with charging device 4Y, 4C, 4M, 4B, and prepares for the next image formation. Further, the intermediate transfer belt 2 after the primary transfer onto the recording paper P is subjected to a cleaning process for residual toner by the belt cleaning device 100.

  Conventionally, each color gradation pattern, chevron patch, and toner consumption pattern formed on the intermediate transfer belt 2 are collected by the belt cleaning device 100. At this time, the belt cleaning apparatus 100 must remove a large amount of toner of the untransferred toner image such as each color gradation pattern, chevron patch, and toner consumption pattern from the intermediate transfer belt 2. However, in a conventional cleaning device including a polarity control unit and a brush roller, or a cleaning device including two brush rollers for removing positive and negative toners, an untransferred toner image can be removed at a time. could not. In such a case, the toner on the intermediate transfer belt 2 that could not be cleaned may be transferred onto the recording paper during the next printing operation, resulting in an abnormal image.

  Therefore, in the copying machine 1 of the present embodiment, the secondary transfer belt 9a is brought into contact with the intermediate transfer belt, a large amount of toner is transferred to the secondary transfer belt 9a, and a large amount of toner is removed by the secondary transfer belt 9a. By doing in this way, the load of the belt cleaning apparatus 100 can be reduced.

  Next, the belt cleaning apparatus 100 of this embodiment is demonstrated. FIG. 7 is an enlarged configuration diagram showing the belt cleaning device 100 of the copying machine 1 and its surroundings in an enlarged manner. 7, the belt cleaning apparatus 100 includes a first cleaning unit 100a and a second cleaning unit 100b adjacent to the first cleaning unit 100a on the downstream side in the belt moving direction. The post cleaning unit 100c is also adjacent to the second cleaning unit 100b on the downstream side in the belt movement direction.

  In the first casing 120a of the first cleaning unit 100a, a first cleaning brush roller 101 serving as a cleaning member that removes transfer residual toner from the surface of the intermediate transfer belt 2 is disposed. Further, the first collection roller 102 which is a collection member that rotates while contacting the first cleaning brush roller 101 to collect the transfer residual toner from the brush roller, and the first transfer roller scrapes the transfer residual toner from the surface of the first collection roller 102 A scraping blade 103 and the like are also provided. The first casing 120a is also provided with a first conveying screw 110a that discharges the transfer residual toner scraped off from the first recovery roller 102 to the outside of the first casing 120a. Further, the first casing 120a is provided with an inlet seal 111a and an outlet seal 112a that are in contact with the intermediate transfer belt 2 and prevent the toner in the first casing 120a from scattering outside the first casing 120a. Has been.

  Most of the secondary transfer residual toner that is not completely transferred by the secondary transfer belt 9a (about 80% of the transfer residual toner) is charged to a positive polarity that is opposite to the negative polarity that is the normal charging polarity of the toner. This is a reversely charged toner. Therefore, in this embodiment, the voltage of the normal charging polarity (negative polarity) is applied to the first cleaning brush roller 101 to electrostatically remove the positive toner on the intermediate transfer belt 2. Further, a negative voltage having an absolute value larger than that of the first cleaning brush roller 101 is applied to the first recovery roller 102. In the belt cleaning device 100, a voltage applied to the first cleaning brush roller 101 is set so that most of the secondary transfer residual toner image is removed by the first cleaning brush roller 101. However, at this time, there is a toner that receives negative charge from the first cleaning brush roller 101 and becomes negative with the normal charging polarity.

  A second cleaning brush roller 104, a second recovery roller 105, a second scraping blade 106, a second conveying screw 110b, an inlet seal 111b, and an outlet seal 112b are disposed in the second casing 120b of the second cleaning unit 100b. Has been.

  The second cleaning unit 100b receives the transfer residual toner charged to the normal charging polarity (negative polarity) that cannot be removed by the first cleaning unit 100a and the negative charge from the first cleaning brush roller 101, and the normal charging polarity (negative polarity). Remove the toner. Therefore, a voltage having a polarity (positive polarity) opposite to the normal charging polarity is applied to the second cleaning brush roller 104 to electrostatically remove the negative polarity toner on the intermediate transfer belt 2. Further, a positive voltage having an absolute value larger than that of the second cleaning brush roller 104 is applied to the second recovery roller 105.

  The two cleaning brush rollers 101 and 104 include a metal rotary shaft member that is rotatably supported, and a brush portion that includes a plurality of raised brushes that are erected on the peripheral surface thereof. The diameter is φ15 to 16 [mm]. The raised nail has a two-layer core-sheath structure in which the inside is made of a conductive material such as conductive carbon and the surface portion is made of an insulating material such as polyester. As a result, the lead has substantially the same potential as the cleaning bias applied to the cleaning brush rollers 101 and 104, and the toner can be electrostatically attracted to the raised surface. As a result, the toner on the intermediate transfer belt 2 is captured by the raised brushes of the cleaning brush rollers 101 and 104.

  The raised brushes of the cleaning brush rollers 101 and 104 may be composed of only conductive fibers instead of the two-layered core-sheath structure. Moreover, you may make it the so-called oblique hair planted in the attitude | position inclined with respect to the normal line direction of a rotating shaft member. Further, the raising of the second cleaning brush roller 104 to which a positive cleaning bias is applied may have a core-sheath structure, and the raising of the first cleaning brush roller 101 may be composed of only conductive fibers. By forming the raised portions of the first cleaning brush roller 101 to which the negative cleaning bias is applied only with conductive fibers, it is possible to easily generate charge injection from the first cleaning brush roller 101 to the toner. Therefore, the first cleaning brush roller 101 can satisfactorily align the toner on the intermediate transfer belt 2 with negative polarity. On the other hand, the brushing of the second cleaning brush roller 104 has a core-sheath structure, so that charge injection into the toner can be suppressed, and the toner on the intermediate transfer belt 2 is suppressed from being positively charged. As a result, the second cleaning brush roller 104 can suppress the generation of toner that cannot be removed electrostatically.

  Further, the two cleaning brush rollers 101 and 104 are bited into the intermediate transfer belt 2 by a biting amount of 1 [mm]. Then, the cleaning brush rollers 101 and 104 are rotationally driven by the driving means so as to move the raising at the contact position in the direction opposite to the moving direction of the intermediate transfer belt (counter direction). By rotating the raised hair so as to move in the counter direction at the contact position, the linear velocity difference between the cleaning brush rollers 101 and 104 and the intermediate transfer belt 2 can be increased. As a result, the probability of contact with the raised hairs until a portion of the intermediate transfer belt 2 passes through the contact range with the cleaning brush rollers 101 and 104 is increased, and the toner can be removed from the intermediate transfer belt 2 satisfactorily. Can do.

  The first cleaning brush roller 101 and the second cleaning brush roller 104 are disposed to face the first facing roller 13 and the second facing roller 14 with the intermediate transfer belt 2 interposed therebetween. The first counter roller 13 and the second counter roller 14 are also electrically conductive and are grounded to form a cleaning electric field between the first cleaning brush roller 101 and the second cleaning brush roller 104, respectively.

  As the first recovery roller 102 and the second recovery roller 105, both are made of stainless steel rollers. Each of the collecting rollers 102 and 105 may be made of any material as long as it can perform the following functions. That is, this function is to transfer the toner adhering to each cleaning brush roller 101, 104 from each cleaning brush roller 101, 104 to each collecting roller 102, 105 by the potential gradient between the raised brush and each collecting roller 102, 105. For example, as each of the collecting rollers 102 and 105, a conductive core metal is covered with a high resistance elastic tube of several [μm] to 100 [μm] or is coated with an insulating coating so that the roller resistance is logR = 12 [Ω · cm ] To 14 [Ω · cm] may be used. By using a roller made of stainless steel as each of the collecting rollers 102 and 105, there is an advantage that the cost can be reduced and the applied voltage can be kept low, and the power can be saved. On the other hand, by setting the roller resistance to logR = 12 [Ω · cm] to 14 [Ω · cm], it is possible to suppress the charge injection into the toner at the time of recovery to each of the recovery rollers 102 and 105. For this reason, it is possible to prevent the toner from having the same polarity as the polarity of the voltage applied to each of the collecting rollers 102 and 105 and reducing the toner collecting rate.

  In FIG. 7, the two-transfer residual toner on the intermediate transfer belt 2 passes over the contact portion between the inlet seal 111 a and the intermediate transfer belt 2 as the intermediate transfer belt 2 moves, and the position of the first cleaning brush roller 101. It is transferred to. A cleaning bias having a normal charging polarity (negative polarity) of toner is applied to the first cleaning brush roller 101. The positively charged toner on the intermediate transfer belt 2 is electrostatically applied to the brush of the first cleaning brush roller 101 by the electric field formed by the potential difference between the intermediate transfer belt 2 and the surface potential of the first cleaning brush roller 101. Adsorb. At this time, a negative charge is received from the first cleaning brush roller 101 by charge injection or discharge, and a part of the toner is charged to the normal charging polarity (negative polarity) and remains on the intermediate transfer belt 2.

  The positive toner transferred to the first cleaning brush roller 101 is transferred to a contact position with the first recovery roller 102 to which a negative recovery bias having an absolute value larger than that of the first cleaning brush roller 101 is applied. . Then, due to the electric field formed by the potential difference between the surface potential of the first cleaning brush roller 101 and the surface potential of the first recovery roller 102, the secondary transfer residual toner in the brush of the first cleaning brush roller 101 is changed to the first recovery roller. Electrostatically transfer onto 102. Then, after being scraped off from the surface of the first recovery roller 102 by the first scraping blade 103, the first cleaning screw 100a transports the toner from the first cleaning unit 100a to the toner reservoir.

  The secondary transfer residual toner on the intermediate transfer belt 2 that could not be removed by the first cleaning brush roller 101 is transferred to a contact position with the second cleaning brush roller 104. A voltage having a polarity (positive polarity) opposite to the normal charging polarity of the toner is applied to the second cleaning brush roller 104. Then, the negatively charged toner on the intermediate transfer belt 2 is electrostatically adsorbed by the electric field formed by the potential difference between the intermediate transfer belt 2 and the surface potential of the second cleaning brush roller 104, and the second cleaning brush. Move to roller 104. Thereafter, after electrostatic transfer to the second recovery roller 105, the second scraping blade 106 scrapes off the second recovery roller 105, and then from the second cleaning unit 100 b to the toner storage unit by the second transport screw 110 b. It is conveyed to.

  In the present embodiment, most of the secondary transfer residual toner can be cleaned by the first cleaning unit 100a and the second cleaning unit 100b. However, in the case of the belt cleaning apparatus 100 including only the first cleaning unit 100a that removes the positive polarity toner and the second cleaning unit 100b that removes the negative polarity toner, a stain-like abnormal image that seems to be poorly cleaned sometimes occurs. there were. In particular, among the plurality of image forming units 66, a noticeable spot-like abnormal image occurred in the Y color solid image formed by the Y image forming unit 66Y arranged at the most upstream in the moving direction of the intermediate transfer belt.

  As a result of intensive studies on the spot-like abnormal images, the present applicants have found the following. That is, there are occasional toners that re-adhere to the intermediate transfer belt 2 from the cleaning brush rollers 101 and 104 (hereinafter referred to as re-adhering toner), and the re-adhering toner appears as a spot-like abnormal image. It was. Therefore, in the belt cleaning apparatus 100, a post cleaning unit 100c for removing the reattached toner from the cleaning brush rollers 101 and 104 to the intermediate transfer belt 2 is provided downstream of the second cleaning unit 100b in the intermediate transfer belt moving direction. .

  The post cleaning unit 100 c has a post cleaning roller 107 made of a conductive sponge that removes the reattached toner on the intermediate transfer belt 2. Further, the post cleaning roller 108 is a recovery member that rotates while contacting the post cleaning roller 107 and recovers toner from the post cleaning roller 107. Further, a post scraping blade 109 for scraping the reattached toner from the surface of the post recovery roller 108 is also provided. The post cleaning roller 107, the post collection roller 108, and the post scraping blade 109 are disposed in the post casing 120c. In the post casing 120c, a post transport screw 110c and the like for discharging the toner scraped off from the post collection roller 108 to the outside of the post casing 120c are also provided. Further, the post casing 120c is provided with an inlet seal 111c and an outlet seal 112c that are in contact with the intermediate transfer belt 2 and prevent the toner in the post casing 120c from scattering outside the post casing 120c. .

  A positive voltage much larger than the absolute value of the voltage applied to each of the cleaning brush rollers 101 and 104 is applied to the post cleaning roller 107. A positive voltage having a larger absolute value than that of the post cleaning roller 107 is applied to the post collection roller 108. Further, the post cleaning roller 107 is disposed so as to face the post facing roller 15 with the intermediate transfer belt 2 interposed therebetween. The post-opposing roller 15 is conductive, and is grounded to form a cleaning electric field with the post cleaning roller 107.

  FIG. 8 is a graph showing the relationship between the voltage applied to the post cleaning roller 107 and the number of spot-like images generated. The number of occurrences on the vertical axis in FIG. 8 indicates that after all 50 solid images of M color, C color, and B color are output continuously, 50 Y color solid images are output, and the output Y color solid image is output. This is the number of sheets that have been visually confirmed and a stain-like abnormal image has been confirmed. As shown in FIG. 8, it can be seen that the number of occurrences of spot-like abnormal images decreases as the voltage applied to the post cleaning roller 107 is increased. In particular, when the post cleaning roller 107 is a conductive sponge roller, the number of occurrences of spot-like abnormal images can be reduced to zero by increasing the applied voltage. In FIG. 8, the cleaning property and re-adhesion property of the re-adhering toner of the post-cleaning unit 100c are evaluated by the number of spot-like images generated, but there is no difference in the tendency among other evaluation methods.

  The post cleaning roller 107 includes a metal rotating shaft member that is rotatably supported and a conductive sponge roller portion that covers the peripheral surface of the rotating shaft member, and has an outer diameter of 15 to 16 mm. The post collection roller 108 has the same configuration as the first collection roller 102 and the second collection roller 105.

  Further, as shown in FIG. 8, in the case of the brush roller, the number of occurrences of spot-like abnormal images can be reduced by increasing the bias, but the number of occurrences cannot be reduced to zero. On the other hand, in the case of the conductive sponge roller, by increasing the bias, the number of occurrences of spot-like abnormal images could be reduced to zero. In the case of the brush roller, the toner adsorbed to the brush may move to the base of the brush, and thus the toner that has moved to the base of the brush is not collected by the collecting roller but remains on the brush. It is considered that the toner remaining on the brush reattaches to the intermediate transfer belt 2 at some point. Therefore, in the case of the brush roller, it is considered that the reattached toner that was removed by itself reattached to the intermediate transfer belt 2 again, and the spot-like image could not be reduced to zero.

  On the other hand, in the conductive sponge roller, the toner adsorbed on the conductive sponge roller portion remains near the surface of the conductive sponge roller portion. Therefore, it is considered that there is hardly any toner that is well collected by the collecting roller and that remains without being collected. As a result, it is considered that the toner reattached to the intermediate transfer belt 2 from the conductive sponge roller is not generated, and the occurrence of the spot-like image can be reduced to zero.

  In this embodiment, a conductive sponge roller is used as the post cleaning roller 107, but a rubber roller, a metal roller, or the like may be used. Even as a rubber roller or a metal roller, the post cleaning roller 107 can be prevented from holding toner. As a result, the reattached toner removed by the post cleaning roller 107 can be prevented from adhering again to the intermediate transfer belt 2 from the post cleaning roller 107, and the number of occurrences of spot-like abnormal images can be reduced to zero. it can.

  In this embodiment, the polarity of the voltage applied to the post cleaning roller 107 is positive. Thereby, the polarity of the voltage applied to the post cleaning roller 107 and the polarity of the voltage applied to the second cleaning brush roller 104 can be made the same. as a result. The potential difference between the second cleaning brush roller 104 and the post cleaning roller 107 is made smaller than when the polarity of the applied voltage of the second cleaning brush roller 104 and the polarity of the applied voltage of the post cleaning roller 107 are different from each other. be able to. Therefore, voltage leakage between the second cleaning brush roller 104 and the post cleaning roller 107 can be suppressed. Further, by setting the polarity of the voltage applied to the post cleaning roller 107 to a positive polarity, it is possible to remove a slight amount of negative polarity toner that could not be removed by the second cleaning brush roller 104.

  The post collection roller 108 is made of a stainless steel roller like the first collection roller 102 and the second collection roller 105, and adopts the same configuration as the first collection roller 102 and the second collection roller 105. Can do. Of course, the post collection roller 108 may be made of any material as long as it can perform the function of transferring the toner adhering to the post cleaning roller 107 to the post collection roller 108 by a potential gradient with the post collection roller 108. Absent. The post recovery roller 108 is also covered with a high resistance elastic tube of several [μm] to 100 [μm] on the conductive mandrel, or further coated with an insulating coating so that the roller resistance is logR = 12 [Ω · cm] You may use what was set to 14 [ohm * cm].

  As described above, the post-cleaning roller 107 is transported by the second cleaning brush roller 104 and the re-attached toner that has re-attached to the intermediate transfer belt 2 and a very small amount of negative-polarity toner that could not be removed by the second cleaning brush roller. Is done. A very small amount of negative polarity toner and re-adhering toner transferred to the post cleaning roller 107 are electrostatically attached to the post cleaning roller 107 to which a voltage having a polarity opposite to the normal charging polarity of the toner is applied. Then, the toner is recovered by the post recovery roller 108 and scraped off from the post recovery roller 108 by the post toner scraping blade 109. After being scraped off from the post collection roller 108 by the post scraping blade 109, it is transported from the post cleaning unit 100c to the toner reservoir by the post transport screw 110c.

The conditions of the first cleaning brush roller 101 and the second cleaning brush roller 104 are as follows.
Brush material: conductive polyester (the first brush has a structure with a conductive material on the fiber surface, the second brush has conductive carbon inside the fiber, and the fiber surface has a polyester, so-called core-sheath structure. (Available at Ashiya and other brush manufacturers.)
Brush resistance: 10 ⁶ [Ω] to 10 ⁸ [Ω]
・ Brush flocking density: 60,000 to 150,000 [lines / inch ² ]
・ Brush fiber diameter: about 25 [μm] to 35 [μm]
-Brush tipping treatment: None-Brush diameter φ: 14 [mm]-20 [mm]
-Brush fiber biting amount into the intermediate transfer belt: 1 [mm] to 1.5 [mm]

The conditions of the post cleaning roller 107 are as follows.
・ Cleaning roller material: Conductive polyurethane (manufactured by Yamauchi Co., Ltd.)
-Diameter φ: 14 [mm] to 20 [mm]
・ Resistance: 10 ^{7.25 ± 0.25} [Ω]
・ Hardness: 35 degrees (Asker C hardness)
・ Intermediate transfer belt biting amount 0.05 [mm] to 0.4 [mm]

  The voltage applied to the first cleaning brush roller 101 is set so that when the secondary transfer residual toner is input to the intermediate transfer belt, the toner (positive toner) charged to the opposite polarity is eliminated. Specifically, the toner after passing through the first cleaning brush roller 101 is aspirated by an experiment and is measured and determined by placing it in a Faraday cage or the like. The second cleaning brush roller 104 is set so that the toner on the intermediate transfer belt 2 can be cleaned. Further, the brush flocking density, brush resistance, fiber diameter, applied voltage, fiber type, and brush fiber biting amount can be optimized by the system, and thus are not limited thereto. Examples of the types of fibers that can be used include nylon, acrylic, and polyester.

The conditions of the first collection roller 102, the second collection roller 105, and the post collection roller 108 are as follows.
・ Recovery roller core material: Stainless steel (SUS303)
-Brush fiber biting amount into the collection roller: 1 [mm] to 1.5 [mm]
・ Roller bite amount: 0.5 [mm]

  The collection roller material, brush fiber entrapment amount, and applied voltage can be optimized by the system, and are not limited thereto.

The conditions of the first scraping blade 103, the second scraping blade 106, and the post scraping blade 109 are as follows.
・ Material: Stainless steel (SUS304)
・ Blade contact angle: 20 [°]
・ Blade thickness: 0.1 [mm]
-Amount of blade biting into the collection roller: 0.5 [mm] to 1.5 [mm]

  The blade contact angle, the blade thickness, and the amount of biting into the collection roller can be optimized by the system, and are not limited thereto.

  In the belt cleaning device 100, a voltage is applied to each of the collecting rollers 102, 105, and 108, each of the cleaning brush rollers 101 and 104, and the post cleaning roller 107, but is not limited thereto. For example, in the first cleaning unit 100 a and the second cleaning unit 100 b, a voltage may be applied only to the collection rollers 102 and 105 without applying a voltage to the cleaning brush rollers 101 and 104. Due to the potential drop due to the fiber resistance of each cleaning brush roller 101, 104, a voltage somewhat lower than the voltage applied to each collecting roller 102, 105 is brought into contact with each collecting roller 102, 105 via each contact. Applied to the brush rollers 101 and 104. As a result, a potential difference is formed between the collection rollers 102 and 105 and the cleaning brush rollers 101 and 104. Therefore, the toner can be electrostatically moved from the cleaning brush rollers 101 and 104 to the recovery rollers 102 and 105 by the potential gradient in the direction of the recovery roller. In the post cleaning unit 100c, it is also possible to adopt a configuration in which a voltage is not applied to the post cleaning roller 107 but a voltage is applied only to the post collection roller 108.

  The cleaning current that provides the best cleaning is a target current that flows through the contact points between the cleaning brush rollers 101 and 104 and the post cleaning roller 107 and the intermediate transfer belt 2. Table 1 shows an example of the target current value.

電圧の単位は［Ｖ］、電流の単位は［μＡ］

The unit of voltage is [V] and the unit of current is [μA].

  Although the voltage of the first cleaning brush roller 101 is fixed, the second cleaning brush roller 104 and the post cleaning roller 107 perform voltage correction so as to become a target current by feedback control, and the values in parentheses are reference values. .

  The process linear velocity in this embodiment is set to 350 [mm / s]. Of course, it is possible to cope with a process linear velocity of 100 [mm / s] to 800 [mm / s]. The target current may be a value proportional to the linear velocity. For example, when the process linear velocity is 175 [mm / s] which is half of 350 [mm / s], the target current value may be half of the process linear velocity 350 [mm / s]. In addition, when the process linear velocity is 700 [mm / s], which is twice the 350 [mm / s], the target current value may be set twice the process linear velocity 350 [mm / s].

  FIG. 9 is a timing chart showing on / off timings of biases applied to the cleaning brush rollers 101 and 104 and the post cleaning roller 107 and biases applied to the recovery rollers 102, 105, and 108. The first cleaning bias in FIG. 9 is a bias applied to the first cleaning brush roller 101. The second cleaning bias is a bias applied to the second cleaning brush roller 104. The third cleaning bias is a bias applied to the post cleaning roller 107. The first collection bias is a bias applied to the first collection roller 102. The second collection bias is a bias applied to the second collection roller 105. The third collection bias is a bias applied to the post collection roller 108.

  Contact / separation between the photoreceptor 3 and the intermediate transfer belt 2 and contact / separation between the intermediate transfer belt 2 and the secondary transfer belt 9a are brought into contact before the photoreceptor 3 is driven. Note that the contact may be made after the start of driving of the photosensitive member 3 or the like, but it is necessary to be before the transfer bias is applied. As shown in FIG. 9, the three cleaning biases and the three recovery biases are controlled to be applied simultaneously after the primary transfer bias and the secondary transfer bias are applied. This is because current from the post cleaning roller 107 and the cleaning brush rollers 101 and 104 flows into the other cleaning brush rollers 101 and 104 and the post cleaning roller 107 via the intermediate transfer belt 2 and interferes with each other. For this reason, they are applied simultaneously as much as possible to prevent an extreme potential difference. For the same reason, it is desirable that the biases are not suddenly started, but are increased in units of several tens [ms] in a small width of about 300 [V], for example. The setting of the cleaning bias and the like is also started at this timing.

  In the copying machine 1 according to the present embodiment, a setting change process of the applied voltage of the belt cleaning apparatus 100 is performed by the control unit 200 in addition to the process control that is performed every time the power is turned on or every time a predetermined number of prints are performed. Specifically, when the measured value of the temperature / humidity sensor changes by a predetermined value or more as compared with the measured value of temperature / humidity recorded during the previous setting change process, the control unit 200 performs the setting change process of the voltage set value. For example, when the temperature change is 10 [° C.] or more or the humidity change is 50 [%] or more, the voltage setting value setting change process is executed for the second cleaning brush roller 104 and the post cleaning roller 107. And the setting change of the applied voltage to the 2nd cleaning brush roller 104 and the post-cleaning roller 107 is performed so that it may become the target electric current value of the setting table corresponding to the present temperature-humidity measurement value. In this embodiment, the temperature / humidity environment is broadly divided into three and has three types of setting values. However, in order to respond more finely, the temperature / humidity environment is further divided into three or more types of setting values. You may have it.

  FIG. 10 is a schematic configuration diagram illustrating a power supply unit included in the belt cleaning device 100. The applied voltage setting change process of the belt cleaning device 100 is performed in a state where the intermediate transfer belt 2 and the belt cleaning device 100 are driven and no toner is input to the belt cleaning device 100. Here, in the present embodiment, the voltage setting values of the applied voltages to the second cleaning brush roller 104 and the post cleaning roller 107, and the second recovery roller 105 and the post recovery roller 108 are simultaneously changed. Therefore, a predetermined voltage is applied from the six power supply units 130, 131, 132, 133, 134, 135 connected to the cleaning rollers 101, 104, the post cleaning roller 107, and the collection rollers 102, 105, 108. .

  Further, in the belt cleaning device 100, in order to simplify the control, the first cleaning power supply unit 130 that outputs a constant voltage corresponding to each environment and the first recovery brush roller 101 and the first recovery roller 102 are provided. Applied from the power supply unit 131. For this reason, in the first cleaning power supply unit 130 that applies a voltage to the first cleaning brush roller 101 and the first recovery power supply unit 131 that applies a voltage to the first recovery roller 102, the current flowing through the power supply 130a and the power supply 131a is supplied. It does not have a detection unit to detect.

  On the other hand, the second cleaning power supply unit 132 that applies a voltage to the second cleaning brush roller 104 includes a power supply 132a that outputs a voltage under constant voltage control, and a detection unit 132b that detects a current value IB2 flowing through the power supply 132a. Yes. The second recovery power supply unit 133 that applies a voltage to the second recovery roller 105 also includes a power supply 133a that outputs the voltage by constant voltage control, and a detection unit 133b that detects the current value IC2 flowing through the power supply 133a. Yes. Furthermore, the third cleaning power supply unit 134 that applies a voltage to the post-cleaning roller 107 includes a power supply 134a that outputs a voltage by constant voltage control, and a detection unit 134b that detects a current value IB3 flowing through the power supply 134a. The third recovery power supply unit 135 that applies a voltage to the post recovery roller 108 is also provided with a power supply 135a that outputs the voltage by constant voltage control and a detection unit 135b that detects the current value IC3 flowing through the power supply 135a. .

  A voltage is specified such that the total value IT2 (IB2 + IC2) of the current value IB2 and the current value IC2 and the total value IT3 (IB3 + IC3) of the current value IB3 and the current value IC3 respectively become target current values. Then, the voltage setting values of the applied voltages of the second cleaning brush and post cleaning roller 107 and the second recovery roller 105 and post recovery roller 108 are simultaneously changed. In the subsequent image forming operation, this set value is used until the voltage set value is next changed.

  FIG. 1 shows a flowchart of an example of the voltage set value changing process. In FIG. 1, the same voltage set value changing process is simultaneously performed on the second cleaning unit 100b and the post cleaning unit 100c. For this reason, the second cleaning unit 100b and the post cleaning unit 100c are not distinguished. Hereinafter, the second cleaning brush roller 104 and the post cleaning roller 107 will be referred to as “cleaning roller” unless otherwise distinguished.

  When the setting of the voltage setting value is changed, the voltage applied first to the cleaning rollers 104 and 107 and the collecting rollers 105 and 108 is stored in the storage unit 201 as the initial value of the voltage when the voltage setting was changed last time. And read it out. The voltage value shown in Table 1 is an example of the initial value. This is because when a voltage far from the voltage to be set is applied, the current flowing through the intermediate transfer belt 2 and flowing between the cleaning rollers increases, and the deterioration of the cleaning roller and the intermediate transfer belt 2 is accelerated.

  First, based on the measured value of the temperature / humidity sensor in the copying machine 1, the target current value of the temperature / humidity environment corresponding to the measured value is read from the setting table shown in Table 1 (S1). Next, the first cleaning bias and the first recovery bias are applied (S2). Next, the second cleaning bias, the third cleaning bias, the second recovery bias, and the third recovery are supplied from the four power sources 132a, 133a, 134a, and 135a connected to the cleaning rollers 104 and 107 and the recovery rollers 105 and 108, respectively. A bias is applied (S3). At this time, the voltage value VB2 and the voltage value VB3 applied to each of the cleaning rollers 104 and 107 are read as the initial values of the voltages when the previous voltage setting change stored in the storage unit 201 as described above. Use things. Further, as the voltage VC2 and the voltage VC3 applied to each of the collecting rollers 105 and 108, a voltage that is 400 [V] higher than the voltage value VB2 and the voltage value VB3 is used.

  Then, current values IB2 and IB3 flowing through the power supplies 132a and 134a for applying a voltage to the cleaning rollers 104 and 107 are detected. Similarly, current values IC2 and IC3 flowing through the power supplies 133a and 135a that apply voltages to the collecting rollers 105 and 108 are detected. Further, a total value IT2 (IB2 + IC2) of the current value IB2 and the current value IC2 and a total value IT3 (IB3 + IC3) of the current value IB3 and the current value IC3 are obtained from the detected current values (S4). Then, it is determined whether the total values IT2 and IT3 are within the range of 80 [%] of the target current value and 120 [%] of the target current value (S5).

  If the total values IT2 and IT3 are in the range of 80% or more of the target current value and 120% or less of the target current value (YES in S5), the voltage values VB2 and VB3 and the voltage value VC2 at that time , VC3 is determined as a voltage setting value (S6). Thereby, a series of voltage setting change processing is complete | finished (S7). On the other hand, if the total values IT2 and IT3 are not within the range of 80% or more of the target current value and 120% or less of the target current value (NO in S5), the total values IT2 and IT3 are the target current value. It is determined whether it is smaller than the lower limit (S8).

  When the total values IT2 and IT3 are smaller than the lower limit of the target current value (YES in S8), a voltage that is 100 [V] higher than the voltage values VB2 and VB3 is obtained, and this is obtained as the voltage values VB′2 and VB′3. do. Further, a voltage that is 400 [V] higher than the voltage values VB′2 and VB′3 is obtained and set as voltage values VC′1, VC′2, and VC′3 (S9). Conversely, when the total values IT2 and IT3 are larger than the lower limit of the target current value (NO in S8), a voltage that is 100 [V] lower than the voltage values VB2 and VB3 is obtained, and this is obtained as the voltage value VB′2, Play VB'3. Further, a voltage that is 400 [V] higher than the voltage values VB'2 and VB'3 is obtained and set as voltage values VC'2 and VC'3 (S10). Then, the voltage values VB'2 and VB'3 are applied to the cleaning rollers 104 and 107, and the voltage values VC'2 and VC'3 are applied to the recovery rollers 105 and 108 (S11). Thereafter, the current values IB2 and IB3 and the current values IC2 and IC3 are detected, and the series of controls as described above are repeated.

  In the present embodiment, the current value is detected at a timing after both the second cleaning brush roller 104 and the post cleaning roller 107 have made one rotation or more after voltage application. This is because, as a result of the study by the present inventor, it has been found that the current of the second cleaning brush roller 104 and the post cleaning roller 107 changes with the subsequent one round. Therefore, if the setting operation is performed while the second cleaning brush roller 104 or the post cleaning roller 107 is making the first rotation, it takes time for setting and is not desirable. Further, the second cleaning brush roller 104 and the post cleaning roller 107 have slight variations in the amount of biting into the intermediate transfer belt 2 due to variations in diameter, and variations in resistance at the time of creation. Therefore, the current is also measured for one rotation of the second cleaning brush roller 104 and the post cleaning roller 107. Specifically, after waiting for a data sample at a time of (intermediate length of the cleaning roller ÷ cleaning roller rotation speed) after the intermediate transfer belt driving is turned ON, the data sample is supplied in units of 10 [ms] in accordance with the CPU clock, for example. Read the value and find the average.

  Further, the current value is detected by turning on the primary transfer bias and the secondary transfer bias, and the intermediate transfer belt 2 to which the primary transfer bias and the secondary transfer bias are added is used by the second cleaning brush roller 104 and the post cleaning roller 107. It is preferable to carry out in the state which passes. This is because the resistance of the intermediate transfer belt 2 may change when a primary transfer bias or a secondary transfer bias is applied to the intermediate transfer belt 2. Therefore, by detecting the current value in this way, each bias can be set in consideration of a change in resistance of the intermediate transfer belt 2, and the bias can be set with higher accuracy.

  These current measurements may be performed during image output as well as during voltage setting. Measuring current during image output is very convenient for service personnel to identify the cause when cleaning failure occurs. If a target current does not flow in the first place when a cleaning failure occurs, the voltage setting may be changed so that the target current flows. If the current is as intended, other causes such as a brush defect can be considered, and the cause can be clarified at an early stage.

  For the current measurement at the time of image output, the above-described detection units 132b and 134b may perform the same operation as at the time of voltage setting at the same timing as the image output. Specifically, the service man operates the operation panel to execute the current measurement mode. When the current measurement mode is executed, the area after secondary transfer of the image calculated from the linear velocity is synchronized with the cleaning rollers 104 and 107 in synchronization with the image output, for example, the registration roller ON timing. Current detection is started at such timing. The second cleaning brush roller 104 and the post cleaning roller 107 are sampled for one round and averaged and displayed on the display unit of the operation panel of the image forming apparatus.

  The voltage setting value changing process of the belt cleaning device 100 that cleans the intermediate transfer belt 2 has been described so far, but the present invention is not limited to this. That is, in the image forming apparatus provided with the photosensitive member, the recording paper conveyance belt, etc., as described above with respect to the cleaning device having three or more cleaning members for cleaning the photosensitive member, the recording paper conveyance belt, etc. as the member to be cleaned. A similar voltage set value change process is performed. Thus, as described above, it is possible to obtain an effect that the control for changing the voltage setting value of the voltage applied to the cleaning member can be suppressed from becoming complicated.

  Further, in the image forming system including the copying machine 1 and a control device for controlling the copying machine 1, the voltage setting value change process control as described above for the belt cleaning device 100 provided in the copying machine 1 is performed. You may comprise so that it may be performed by the control part provided in the control apparatus. In addition, the server 200 provided outside the copying machine 1 serves as a voltage setting value changing unit of the control unit 200 provided in the copying machine 1, and the copying machine 1 is controlled by the server via the network. Also good.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
Three or more cleaning members such as a first cleaning brush roller 101, a second cleaning brush roller 104, and a post cleaning roller 107 that electrostatically remove toner on a member to be cleaned such as the intermediate transfer belt 2, and the three A plurality of power sources such as power sources 130a, 132a, 134a for applying a voltage according to a voltage set value in a voltage set value storage means such as the storage unit 201 to each of the cleaning members, the cleaning member, and the object to be cleaned The voltage setting value in the voltage setting value storage means is changed based on the current detection means such as the detection units 133b and 134b that detect the amount of current flowing through the contact point and the current amount detected by the current detection means. A cleaning device such as a belt cleaning device 100 having voltage setting value changing means such as a control unit 200. The at least one power source among the plurality of power sources is a first power source that outputs a predetermined voltage to be applied to the cleaning member, and the remaining power source different from the at least one power source among the plurality of power sources. Is a second power source that outputs a voltage to be applied to the cleaning member by constant voltage control, and each of the second power sources is in a state where a voltage is simultaneously applied to all of the three or more cleaning members by the plurality of power sources. The amount of current flowing through each contact portion between the cleaning member to which the voltage is applied from the power source and the object to be cleaned is detected by the current amount detection means, and output from each second power source based on the detection result. The voltage setting value of the voltage to be changed is changed by the voltage setting value changing means so that a target current amount flows through each contact location.
In (Aspect A), at least one of the plurality of power supplies that apply a voltage to each of the three or more cleaning members is a first power supply that outputs the predetermined voltage, and the rest is the constant voltage control. This is the second power supply that outputs. About a 1st power supply, a predetermined voltage is output irrespective of the electric current amount which flows into the said contact location. As a result, for the first power source, the control for changing the voltage setting value by the voltage setting value changing unit based on the amount of current flowing through the contact point detected by the current detecting unit is not performed, and the current only for the second power source. Control for changing the voltage setting value based on the amount is performed. Therefore, as compared with the case where control is performed to change the voltage setting value based on the current value for all of a plurality of power supplies, the amount of power to be changed is less than the voltage setting value based on the current value, It can suppress that control becomes complicated.
(Aspect B)
In (Aspect A), the first power supply outputs the predetermined voltage by constant voltage control. According to this, as described in the above embodiment, it is possible to further suppress the complicated control for changing the voltage set value.
(Aspect C)
In (Aspect A) or (Aspect B), the detection of the amount of current flowing through the contact location by the current detection means is performed after a voltage is applied from the second power source to the cleaning member and current is passed through the contact location. , After the cleaning member has rotated one or more times. According to this, as described in the above embodiment, the accuracy of the voltage setting value to be changed can be improved.
(Aspect D)
In (Aspect A), (Aspect B), or (Aspect C), the amount of current flowing through the contact location is detected by the current amount detection means during at least one rotation of the cleaning member, and the voltage setting value change is performed. The voltage set value to be changed is determined by means. According to this, as described in the above embodiment, the voltage setting value can be determined based on the voltage change due to the resistance unevenness in the circumferential direction of the cleaning member.
(Aspect E)
An image carrier such as the intermediate transfer belt 2; a toner image forming unit such as an image forming unit 66 that forms a toner image on the image carrier; and a toner image formed on the image carrier such as a recording paper In the image forming apparatus such as the copying machine 1 provided with a cleaning unit such as a belt cleaning device 100 that removes toner remaining on the image carrier after being transferred onto the recording medium, the cleaning unit (Aspect A ), (Aspect B), (Aspect C) or (Aspect D) cleaning apparatus was used. According to this, as described in the above embodiment, it is possible to prevent the control for changing the voltage setting value of the voltage applied to the cleaning member from becoming complicated.
(Aspect F)
In (Aspect F), the intermediate transfer member is an elastic intermediate transfer belt, and when the voltage setting value is changed by the voltage setting value changing unit, toner is transferred from the image carrier to the intermediate transfer belt. A voltage is applied from the second power source to a region of the intermediate transfer belt to which a primary transfer electric field is applied and a secondary transfer electric field for transferring toner from the intermediate transfer belt to a recording medium is applied. After passing through the location facing the cleaning member, the current detection means detects the amount of current at the contact location. According to this, as described in the above embodiment, the accuracy of the voltage setting value to be changed can be improved.
(Aspect G)
(Aspect F) includes a secondary transfer member such as a secondary transfer belt 9a that contacts the intermediate transfer belt and forms a secondary transfer electric field with the intermediate transfer belt. When the intermediate transfer belt is cleaned, the secondary transfer member is brought into contact with the intermediate transfer belt, and the toner on the intermediate transfer belt is transferred onto the secondary transfer member. A voltage having the same polarity as the normal charging polarity of the toner is applied from the first power source to the most upstream side cleaning member such as the first cleaning brush roller 101 on the most upstream side in the moving direction of the intermediate transfer belt. The second cleaning brush roller 104 and the post cleaning roller 1 located downstream of the upstream cleaning member in the intermediate transfer belt moving direction. Downstream cleaning member such as 7, a voltage is applied from the second power supply. According to this, as described in the above embodiment, a voltage is applied from the first power supply to the most upstream cleaning member that has little influence on the cleaning performance even if the amount of current flowing through the contact portion is slightly deviated from the target. Therefore, it is possible to suppress the occurrence of defective cleaning.
(Aspect H)
In (Aspect G), the voltage applied from the second power source to the downstream cleaning member has a polarity opposite to the normal charging polarity of the toner. According to this, as described in the above embodiment, the toner charged on the intermediate transfer belt after passing through the most upstream cleaning member and having the same polarity as the normal charging polarity of the toner is removed by the downstream cleaning member. Can be removed.
(Aspect I)
In (Aspect E), (Aspect F), (Aspect G) or (Aspect H), for each image output, a current corresponding to one rotation of the cleaning member is detected by the current detection means, and the detection result is displayed on the operation panel. Can be displayed on display means such as a display unit. According to this, as described in the above embodiment, it is possible for a serviceman to check whether the voltage is set so as to achieve the target current by looking at the display means.
(Aspect J)
A voltage to be applied to three or more cleaning members such as the first cleaning brush roller 101, the second cleaning brush roller 104, and the post cleaning roller 107 that electrostatically removes toner on the object to be cleaned such as the intermediate transfer belt 2. In the voltage setting method for setting, the voltage applied to at least one of the three or more cleaning members is set to a constant voltage value, and the voltage is applied to all of the three or more cleaning members simultaneously. Each of the cleaning members other than the cleaning member to which the voltage of the constant voltage value is applied and the object to be cleaned are each detected in an amount of current flowing, and the detection result is a target current amount. A voltage value of a voltage to be applied to a cleaning member other than the cleaning member to which the constant voltage value is applied is set. To. According to this, as described in the above embodiment, it is possible to prevent the setting of the voltage value of the voltage applied to the cleaning member from becoming complicated.
(Aspect K)
A copier 1 having three or more cleaning members such as a first cleaning brush roller 101, a second cleaning brush roller 104, and a post cleaning roller 107 that electrostatically removes toner on an object to be cleaned such as the intermediate transfer belt 2. In the image forming system including the image forming apparatus, the image forming apparatus applies a voltage according to the voltage setting value in the voltage setting value storage unit such as the storage unit 201 to each of the three or more cleaning members. A plurality of power sources such as power sources 130a, 132a, and 134a, and current detection means such as detectors 133b and 134b that detect the amount of current flowing through the contact portion between the cleaning member and the object to be cleaned. Based on the amount of current detected by the current detection means, the voltage set value in the voltage set value storage means is changed. A control device having a voltage setting value changing means sets at least one first power source among the plurality of power sources so as to output a predetermined voltage to be applied to the cleaning member. With respect to the remaining second power sources different from the at least one power source, each of the cleaning members to which a voltage is applied from each of the second power sources in a state where a voltage is simultaneously applied to all of the three or more cleaning members, The amount of current flowing through each contact location with the object to be cleaned is detected by the current amount detection means, and the voltage setting value of the voltage output from each second power source is aimed at each contact location based on the detection result. Set so that the amount of current flows. According to this, as described in the above embodiment, it is possible to prevent the control for changing the voltage setting value of the voltage applied to the cleaning member from becoming complicated.

DESCRIPTION OF SYMBOLS 1 Copier 2 Intermediate transfer belt 2a Belt tension roller 2b Belt tension roller 2c Secondary transfer counter roller 2d Tension roller 3 Photoconductor 4 Charging device 5 Writing device 6 Developing device 7 Primary transfer roller 8 Drum cleaning device 9 Secondary transfer Device 9a Secondary transfer belt 9b Secondary transfer roller 9c Separation roller 9d Sensor facing roller 9e Secondary transfer belt cleaning facing roller 10 Image forming unit 11 Fixing device 12 Conveyance path switching claw 13 First facing roller 14 Second facing roller 15 Post Counter roller 20 Paper feed unit 21 Paper feed cassette 22 Transport roller 23 Registration roller 30 Document scanning unit 31 Document placement table 32 Scanner 33 Automatic document feeder 40 Manual feed tray 41 Feeding roller 50 Paper discharge tray 66 Image forming unit 91 Conveying belt 91a Transport bell Driving roller 91b Conveyor belt driven roller 100 Belt cleaning device 100a First cleaning unit 100b Second cleaning unit 100c Post cleaning unit 101 First cleaning brush roller 102 First recovery roller 103 First scraping blade 104 Second cleaning brush roller 105 First cleaning brush Two recovery rollers 106 Second scraping blade 107 Post cleaning roller 108 Post recovery roller 109 Post scraping blade 110a First transport screw 110b Second transport screw 110c Post transport screw 111a Inlet seal 111b Inlet seal 111c Inlet seal 112a Outlet seal 112b Outlet Seal 112c Outlet seal 120a First casing 120b Second casing 120c Post casing 130 First cleaning power supply unit 130a Power supply 131 First recovery power supply unit 131a Power supply 132 Second cleaning power supply unit 132a Power supply 132b Detection unit 133 Second recovery power supply unit 133a Power supply 133b Detection unit 134 Third cleaning power supply unit 134a Power supply 134b Detection unit 135 Third recovery power supply unit 135a Power supply 135b Detection unit 190 Secondary transfer belt cleaning device 200 Control unit 201 Storage unit 211 Base layer 212 Elastic layer 213 Surface layer 300 Optical sensor

JP 2014-215602 A

Claims (11)

Three or more cleaning members that electrostatically remove toner on the object to be cleaned;
A plurality of power supplies for applying a voltage according to the voltage set value in the voltage set value storage means to each of the three or more cleaning members;
Current detection means for detecting the amount of current flowing through the contact portion between the cleaning member and the object to be cleaned;
In a cleaning apparatus comprising: a voltage setting value changing unit that changes a voltage setting value in the voltage setting value storage unit based on a current amount detected by the current detection unit;
At least one power source among the plurality of power sources is a first power source that outputs a predetermined voltage to be applied to the cleaning member,
The remaining power source different from the at least one power source among the plurality of power sources is a second power source that outputs a voltage to be applied to the cleaning member by constant voltage control,
A current that flows in each contact location between each of the cleaning members to which the voltage is applied from each second power source and the object to be cleaned in a state where a voltage is simultaneously applied to all of the three or more cleaning members by the plurality of power sources. The amount of current is detected by the current amount detection means, and based on the detection result, the voltage setting value of the voltage output from each second power source is set to the voltage setting value so that the target current amount flows to each contact location. A cleaning device that is changed by a changing means. The cleaning device according to claim 1,
The cleaning device according to claim 1, wherein the first power source outputs the predetermined voltage by constant voltage control. The cleaning device according to claim 1 or 2,
Detection of the amount of current flowing through the contact location by the current detection means is performed after a voltage is applied from the second power source to the cleaning member and current is passed through the contact location, and then the cleaning member has rotated one revolution or more. A cleaning device. The cleaning device according to claim 1, 2 or 3,
Detection of the amount of current flowing through the contact location by the current amount detection means is performed for at least one rotation of the cleaning member, and the voltage setting value to be changed by the voltage setting value changing means is determined. Cleaning device. An image carrier;
Toner image forming means for forming a toner image on the image carrier;
An image forming apparatus comprising: a cleaning unit that removes toner remaining on the image carrier after the toner image formed on the image carrier is transferred onto a recording medium.
An image forming apparatus using the cleaning device according to claim 1, 2, 3, or 4 as the cleaning unit. The image forming apparatus according to claim 5, wherein
The intermediate transfer body is an intermediate transfer belt having elasticity,
When the voltage setting value is changed by the voltage setting value changing means, a primary transfer electric field is applied to the intermediate transfer belt to transfer toner from the image carrier, and toner is transferred from the intermediate transfer belt to the recording medium. After the region of the intermediate transfer belt to which a secondary transfer electric field for transferring the voltage is applied passes through a location facing the cleaning member to which a voltage is applied from the second power source, the contact location is detected by the current detection unit. An image forming apparatus in which the amount of current is detected. The image forming apparatus according to claim 6.
A secondary transfer member that contacts the intermediate transfer belt and forms a secondary transfer electric field with the intermediate transfer belt;
When the intermediate transfer belt is cleaned by the cleaning device, the secondary transfer member is brought into contact with the intermediate transfer belt, and the toner on the intermediate transfer belt is transferred onto the secondary transfer member.
Among the three or more cleaning members, a voltage having the same polarity as the normal charging polarity of the toner is applied from the first power source to the most upstream cleaning member on the most upstream side in the intermediate transfer belt moving direction.
An image forming apparatus, wherein a voltage is applied from the second power source to a downstream cleaning member located downstream of the most upstream cleaning member in the intermediate transfer belt moving direction. The image forming apparatus according to claim 7.
An image forming apparatus, wherein a voltage applied from the second power source to the downstream cleaning member has a polarity opposite to a normal charging polarity of toner. The image forming apparatus according to claim 5, 6, 7, or 8.
An image forming apparatus characterized in that, for each image output, a current corresponding to one rotation of the cleaning member is detected by the current detection means, and the detection result can be displayed on a display means. In a voltage setting method for setting a voltage to be applied to three or more cleaning members that electrostatically remove toner on an object to be cleaned,
The voltage applied to at least one of the three or more cleaning members is set to a constant voltage value,
A voltage is simultaneously applied to all of the three or more cleaning members, and the amount of current flowing through each contact portion between the cleaning member other than the cleaning member to which the constant voltage value is applied and the object to be cleaned is detected. The voltage setting method is characterized in that the voltage value to be applied to a cleaning member other than the cleaning member to which the voltage of the constant voltage value is applied is set so that the detection result becomes a target current amount. In an image forming system comprising an image forming apparatus having three or more cleaning members that electrostatically remove toner on a member to be cleaned,
The image forming apparatus includes:
A plurality of power supplies for applying a voltage according to the voltage set value in the voltage set value storage means to each of the three or more cleaning members;
Current detection means for detecting the amount of current flowing through the contact portion between the cleaning member and the object to be cleaned;
A control device comprising a voltage set value changing means for changing a voltage set value in the voltage set value storage means based on the amount of current detected by the current detecting means,
At least one first power source among the plurality of power sources is set to output a predetermined voltage to be applied to the cleaning member, and the remaining second second power different from the at least one power source among the plurality of power sources. As for the power source, the amount of current flowing to each contact location between each of the cleaning members to which the voltage is applied from each second power source and the object to be cleaned in a state where the voltage is simultaneously applied to all of the three or more cleaning members. Is detected by the current amount detection means, and based on the detection result, the voltage setting value of the voltage output from each second power source is set so that the target current amount flows to each contact location. An image forming system.

Images