JP5958788B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to cleaning of an endless intermediate transfer belt used in an intermediate transfer type image forming apparatus.

  2. Description of the Related Art Conventionally, in image forming apparatuses such as printers, fax machines, copiers, and multi-function machines, intermediate transfer type image forming apparatuses using an endless intermediate transfer belt as a component are known. For example, in a color image forming apparatus, an intermediate transfer that is arranged to face a plurality of photosensitive drums that are cylindrical latent image carriers that are driven to rotate, and is rotated at the same peripheral speed as the photosensitive drums in contact with the drums. Some have a belt.

  In an image forming apparatus including such an intermediate transfer belt, a developing unit that visualizes a latent image formed on a photosensitive drum and an intermediate transfer of a toner image (developed image) formed on the photosensitive drum. Primary transfer means for transferring onto the belt, and secondary transfer means for secondary transfer of the toner image on the intermediate transfer belt to the transfer material. By sequentially performing primary transfer to the intermediate transfer belt by the primary transfer unit, a superimposed image is formed on the intermediate transfer belt, and this superimposed image is collectively transferred to a transfer material by secondary transfer. A color image is obtained.

  However, the transfer rate of the toner image from the intermediate transfer belt to the transfer material is not 100%, and some residual toner (hereinafter referred to as residual toner) exists on the intermediate transfer belt. Conventionally, the residual toner has been cleaned by scraping with a blade-like cleaning member (hereinafter referred to as a blade) such as a rubber blade. Conventionally, there has been a problem of deterioration of the intermediate transfer belt cleaning performance due to toner adhesion to the blade and biting of paper dust. In order to suppress the occurrence of such problems, various configurations have been conventionally proposed. For example, Patent Document 1 describes an image forming apparatus having the following configuration. At the end of image formation, the intermediate transfer belt is reversely rotated to separate the toner and paper powder adhering to the edge portion of the blade during image formation, thereby preventing the toner and paper powder from sticking to the edge portion. .

  However, with the recent increase in the demand for higher image quality, the toner has become smaller and spherical in size year after year, making it difficult to clean with a blade. Furthermore, there is an increasing demand for various types of paper, making it easier to bite paper dust with a blade than ever before, and the reduced-diameter and spherical toner can be made by paper dust biting into the blade. A new problem has arisen that the cleaning performance deteriorates due to passing through the gap. Such a decrease in cleaning performance cannot be dealt with only by the configuration described in Patent Document 1, and an abnormal image is generated due to the deterioration in cleaning performance as described above, particularly when continuous image formation is performed. In addition, problems such as image quality degradation have become prominent.

  The present invention has been made in view of the above problems, and its object is to adhere residual toner and paper dust to the blade even when continuous image formation is performed using toner having a reduced diameter and a spherical shape. It is an object of the present invention to provide an image forming apparatus capable of suppressing a decrease in cleaning performance due to the above.

In order to achieve the above object, an invention according to claim 1 is directed to an endless intermediate transfer belt onto which a toner image on an image carrier is transferred, and to the image carrier through an intermediate transfer belt. A primary transfer bias roller provided, a plurality of tension rollers for stretching the intermediate transfer belt, and a secondary transfer bias for secondary transfer of the toner image transferred onto the intermediate transfer belt onto a recording medium , A belt cleaning member that removes transfer residual toner on the surface of the intermediate transfer belt, a cleaning counter roller that faces the belt cleaning member via the intermediate transfer belt, and the intermediate transfer an image forming apparatus comprising means for belt endlessly moving, and applies the secondary transfer bias of the same polarity as the bias voltage to the cleaning counter roller Giving partial vibration to the intermediate transfer belt by Rukoto, removal of the relative position between the intermediate transfer belt and the belt cleaning member, or by changing the contacting posture, material adhering to the belt cleaning member It is characterized by performing.
In the present invention, partial vibration is applied to the intermediate transfer belt to change the relative position or contact position between the intermediate transfer belt and the belt cleaning member. Can be removed by friction with the intermediate transfer belt.
Further, since the vibration applied to the intermediate transfer belt is partial, the influence of the applied vibration is not transmitted to the primary transfer nip formed by the primary transfer bias roller and the image carrier via the intermediate transfer belt. it can. Here, in order to give a partial vibration to the intermediate transfer belt, for example, the following configuration can be adopted. A belt cleaning member is arranged on the upstream side of the primary transfer nip portion on the most upstream side in the endless movement direction in the section of the intermediate transfer belt in which a plurality of image carriers are arranged in parallel upward, and the driving roller further on the upstream side Shall be placed. A belt urging roller that urges the intermediate transfer belt from the surface is disposed between the primary transfer nip portion and the belt cleaning member. With this arrangement, even if the cleaning counter roller is moved up and down to apply vibration to the intermediate transfer belt, the influence of vibration on the primary transfer nip portion side can be suppressed by the belt urging roller. Further, the influence of vibration on the upstream side of the belt cleaning member is suppressed by the driving roller. Therefore, the vibration applied to the intermediate transfer belt can be a partial vibration between the belt urging roller and the driving roller. Then, it is possible to remove the adhered substances such as toner and paper dust adhered to the front end of the belt cleaning member so that the influence of the applied vibration is not transmitted to the primary transfer nip portion.
Since it can be removed in this way, it is possible to remove substances adhering to the tip of the belt cleaning member, such as toner and paper dust, both during and after image formation, resulting in poor cleaning performance of the intermediate transfer belt. Can be suppressed.

The present invention can remove substances adhering to the tip of the belt cleaning member, such as toner and paper dust, during image formation and after image formation, and can suppress deterioration in cleaning performance of the intermediate transfer belt. .
Accordingly, it is possible to provide an image forming apparatus capable of suppressing a reduction in cleaning performance due to adhesion of residual toner or paper powder to the blade even when continuous image formation is performed using toner having a reduced diameter and a spherical shape. .

1 is a schematic explanatory diagram of a main part in a full color mode of a printer according to an embodiment. FIG. FIG. 2 is a schematic explanatory diagram of a main part in a monochrome mode of a printer according to an embodiment. The schematic diagram for demonstrating shape factor SF-1. The schematic diagram for demonstrating shape factor SF-2. FIG. 3 is an explanatory diagram illustrating a configuration of a blade cleaning mechanism of the belt cleaning blade according to the first exemplary embodiment. FIG. 6 is an explanatory diagram illustrating a configuration of a blade cleaning mechanism of a belt cleaning blade according to a second embodiment. FIG. 9 is an explanatory diagram illustrating a configuration of a blade cleaning mechanism of a belt cleaning blade according to a third embodiment. FIG. 10 is an explanatory diagram illustrating a configuration of a blade cleaning mechanism of a belt cleaning blade according to a fourth embodiment.

  Hereinafter, an embodiment in which the present invention is applied to an electrophotographic color printer (hereinafter simply referred to as a printer) as an image forming apparatus will be described with reference to the drawings. First, an overall outline of the printer of this embodiment common to the respective examples will be described. Here, FIG. 1 is a schematic explanatory diagram of main parts when the printer according to the present embodiment is in full color mode, and FIG. 2 is a schematic explanatory diagram of main parts when the printer according to the present embodiment is in monochrome mode. FIG. 3 is a schematic diagram for explaining the shape factor SF-1, and FIG. 4 is a schematic diagram for explaining the shape factor SF-2. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

  As shown in FIG. 1, the printer of this embodiment includes four process units for forming yellow (Y), magenta (M), cyan (C), and black (K) toner images. 20Y, M, C, K are provided. Further, an intermediate transfer unit 32, a fixing device 50, a pair of registration rollers (not shown), an optical writing unit, a paper feed cassette, and the like are also provided.

  The process units 20Y, M, C, and K are provided with photosensitive drums 1Y, 1M, 1C, and 1K, which are image carriers. Around each photosensitive drum 1, a photosensitive member cleaning device 6 using a cleaning blade, a static eliminator (not shown), a charging device 2, a developing device 4, and the like are provided and are arranged to face the intermediate transfer belt 5. . Further, an optical writing unit (not shown) is provided above each process unit 20 and includes a laser diode, a polygon mirror, various lenses, and the like. Then, the photosensitive drums 1Y, 1M, 1C, and 1K of the process units 20Y, M, C, and K are optically scanned with scanning light that is emitted based on image information transmitted from an external personal computer or the like. Specifically, the photosensitive drums 1Y, 1M, 1C, and 1K of the process units 20Y, 20M, 20C, and 20K are rotationally driven in the clockwise direction in the drawing by driving means (not shown). The optical writing unit irradiates the rotating photosensitive drums 1Y, 1M, 1C, and 1K with scanning light: Ly, m, c, and k while deflecting them in the rotational axis direction, thereby performing optical scanning. Process. Thereby, electrostatic latent images based on Y, M, C, and K image information are formed on the photoreceptors 3Y, 3M, 3C, and 3K.

  The developing devices 4Y, 4M, 4C, and 4K use toners of yellow, magenta, cyan, and black, respectively, and electrostatic latent images formed on the photosensitive drums 1Y, 1M, 1C, and 1K, respectively. A toner is attached to form a visible image. When forming a full-color image, each developing device 4 forms a visible image with toner in the order of arrangement in the moving direction of the intermediate transfer belt 5, and the visible images of the respective colors are sequentially transferred onto the intermediate transfer belt 5. Thus, a full color image is formed.

  The intermediate transfer belt 5 is stretched by a drive roller 7 and a tension roller 8 and is driven by a drive motor (not shown), and the process speed is adjusted to 150 mm / sec. Further, the intermediate transfer belt 5 is provided with primary transfer bias rollers 9Y, 9M, 9C, and 9K that are driven rollers on the inner side, a belt cleaning counter roller 14, and the like. Each roller is supported by a unit side plate (not shown) of the intermediate transfer unit 32 from both sides of the intermediate transfer belt 5 via each bearing and arm. Here, the driving roller 7 serves as a counter roller of the secondary transfer roller 15 and also as a secondary transfer bias roller.

  The primary transfer bias rollers 9Y, 9M, 9C, and 9K are arranged at the contact portions between the respective photosensitive drums 1 and the intermediate transfer belt 5, and a predetermined primary transfer bias voltage is applied during the primary transfer. It will be. In this embodiment, +1800 [V] is set to be applied.

The intermediate transfer belt 5 is made of vinylden fluoride (PVDF), ethylene-tetrafluoroethylene copolymer (ETFE), polyimide (PI), polycarbonate (PC) or the like in a single layer or a plurality of layers, such as carbon black. Conductive material is dispersed. The volume resistivity is adjusted to be in the range of 10 ⁸ to 10 ¹² [Ωcm], and the surface resistivity is adjusted to be in the range of 10 ⁹ to 10 ¹³ [Ω / □]. If necessary, a release layer may be coated on the surface of the intermediate transfer belt 5. Materials used for the coating include ethylene-tetrafluoroethylene copolymer (ETFE), polytetrafluoroethylene (PTFE), vinylidene fluoride (PVDF), perfluoroalkoxy fluororesin (PEA), and tetrafluoroethylene. -Fluororesin such as propylene hexafluoride copolymer (FEP) and vinyl fluoride (PVF) can be used, but is not limited thereto.

  The method of manufacturing the intermediate transfer belt 5 includes a casting method and a centrifugal molding method, and the surface thereof may be polished as necessary. If the volume resistivity of the intermediate transfer belt 5 exceeds the above-described range, the bias voltage required for transfer increases, which increases the power supply cost. Further, since the charging potential of the intermediate transfer belt 5 becomes high and the self-discharge becomes difficult in the transfer process, the transfer paper peeling process, etc., it is necessary to provide a static elimination means. Also, if the volume resistivity and surface resistivity are below the above ranges, the charge potential decays quickly, which is advantageous for static elimination by self-discharge, but toner scatter occurs because the current during transfer flows in the surface direction. End up. Therefore, the volume resistivity and surface resistivity of the intermediate transfer belt 5 in the present invention must be within the above ranges. The volume resistivity and surface resistivity were measured by connecting an HRS probe (inner electrode diameter 5.9 [mm], ring electrode inner diameter 11 [mm]) to a high resistivity meter (Mitsubishi Chemical Corporation: Hiresta). Then, a voltage of 100 [V] (surface resistivity is 500 [V]) was applied to the front and back of the intermediate transfer belt 5 and the measured value after 10 seconds was used.

  The intermediate transfer belt 5 is provided with a belt cleaning blade 10 that removes residual toner, paper dust, and the like on the intermediate transfer belt 5. The belt cleaning blade 10 is made of urethane rubber, and is configured to dam and clean the toner so as to be pressed against the intermediate transfer belt 5 toward the blade facing roller 14. In the present embodiment, the belt cleaning blade 10 is held in a bent state by a blade holding member (not shown) so that the tip of the belt cleaning blade 10 is pressed against the intermediate transfer belt 5. For this reason, an operation is given to a partial section of the intermediate transfer belt 5 including a portion where the belt cleaning blade 10 abuts by a blade cleaning mechanism which will be described in detail, and the blade facing roller 14 vibrates or moves in the vertical direction. Even so, the tip of the belt cleaning blade 10 is kept in contact with the surface of the intermediate transfer belt 5. The relative position or contact posture between the intermediate transfer belt 5 and the tip of the belt cleaning blade 10 is changed by the vertical vibration or movement of the blade facing roller 14. If it changes in this way, even if the intermediate transfer belt 5 is not moving endlessly, the intermediate transfer belt 5 and the tip of the belt cleaning blade 10 will rub. In this embodiment, the belt cleaning blade 10 is bent and brought into contact with the intermediate transfer belt 5, but the present invention is not limited to such a configuration. For example, the blade holding member that holds the belt cleaning blade 10 may be provided with an urging means so that the tip of the belt cleaning blade 10 contacts the intermediate transfer belt 5 with a predetermined contact pressure.

  A brush roller 12 for applying the solid lubricant 11 to the intermediate transfer belt 5 is disposed in contact therewith. A brush facing roller 13 is disposed at a position facing the brush roller 12 and the intermediate transfer belt 5. The reason why the solid lubricant 11 is applied to the intermediate transfer belt 5 in this way is to facilitate cleaning by the belt cleaning blade 10.

  As the lubricant to be molded into the solid lubricant 11, a fatty acid metal salt having a linear hydrocarbon structure is used. The fatty acid metal salt contains at least one fatty acid selected from stearic acid, palmitic acid, myristic acid and oleic acid, and at least one metal selected from zinc, aluminum, calcium, magnesium and lithium The fatty acid metal salt containing is mentioned. Among them, zinc stearate is the most preferable material in terms of cost, quality stability, and reliability because it is produced on an industrial scale and has been used in many fields. However, the higher fatty acid metal salts that are generally used industrially are not the simple substance composition of the name, but include other fatty acid metal salts, metal oxides, and free fatty acids that are more or less similar. The fatty acid metal salt used in the form is no exception.

  These lubricants are supplied in the form of powder in small amounts. As a specific method, the lubricant is solidly formed on the block by a brush such as the brush roller 12 as in this embodiment. There are a method of scraping and applying the toner, a method of supplying the toner by external addition, and the like. However, when the lubricant is supplied externally to the toner, the supply amount depends on the output image area and cannot always be supplied to the entire belt surface. For this reason, when it is intended to supply the lubricant stably over the entire belt surface with a simple apparatus configuration, a method of scraping and applying the solid lubricant 11 with the brush roller 12 as in this embodiment is preferable.

  In order to scrape off the solid lubricant 11 with the brush roller 12, the solid lubricant 11 is pressed against the brush roller 12 with a force of 1N to 4N by a lubricant pressurizing means such as a spring. Since the width of the solid lubricant 11 needs to be set wider than the width of the image formed on the intermediate transfer belt 5, in this embodiment, the width is set to 304 [mm] or more. Further, the width of the brush roller 12 needs to be larger than the width of the solid lubricant 11 in order to scrape the solid lubricant 11 uniformly. A brush facing roller 13 is provided at a position facing the brush roller 12 via the intermediate transfer belt 5. Further, in order to suppress the vibration of the intermediate transfer belt 5 in the image forming unit, the primary transfer rollers 9C, 9M, 9Y, 9K and the belt cleaning blade 10 and the primary transfer rollers 9C, 9M, 9Y, The belt is urged by a belt urging roller 17 between 9K and the brush roller 12. Here, in this embodiment, the belt urging roller 17 is provided on the outer side of the intermediate transfer belt, but the same effect can be obtained on the inner side.

  Of the primary transfer rollers 9K, 9C, 9M, and 9Y, the color primary transfer rollers 9C, 9M, and 9Y can be brought into contact with and separated from the intermediate transfer belt 5 by a conventionally known contact and separation mechanism (not shown). In the full color mode, the primary transfer rollers 9C, 9M, and 9Y contact the intermediate transfer belt 5 as shown in FIG. 1 from the state in the monochrome mode shown in FIG. In this state, the intermediate transfer belt is brought into contact with and wound around each photosensitive drum 1. The monochrome primary transfer roller 9K is wound around the intermediate transfer belt 5 regardless of the contact / separation mechanism.

  When the intermediate transfer unit 32 is pulled out, the monochrome primary mode prevents the color primary transfer rollers 9C, 9M, and 9Y from coming into contact with the opposing photosensitive drums 1 respectively. Note that a method of stopping in the monochrome mode when printing is stopped is employed so that the intermediate transfer unit 32 may be pulled out at any time.

The secondary transfer roller 15 is configured by covering a metal core such as SUS with an elastic body such as urethane adjusted to a resistance value of 10 ⁶ to 10 ¹⁰ [Ω] with a conductive material. Here, if the resistance value of the secondary transfer roller 15 exceeds the above range, it becomes difficult for a current to flow. Therefore, a higher voltage must be applied in order to obtain a required transfer property, resulting in an increase in power supply cost. . In addition, since a high voltage is applied, a discharge occurs in the gap before and after the transfer portion nip, so that white spots are lost due to the discharge on the halftone image. On the other hand, if the resistance value of the secondary transfer roller 15 is below the above range, transferability between a multi-color image portion (for example, a three-color superimposed image) and a single-color image portion existing on the same image cannot be achieved. This is because the resistance value of the secondary transfer roller 15 is low, so that a sufficient current flows to transfer the monochrome image portion at a relatively low voltage. However, it is optimal for the monochrome image portion to transfer the multiple color image portion. Since a voltage value higher than the voltage is required, setting a voltage that can transfer a plurality of color image portions causes an excessive transfer current in a single-color image, resulting in a reduction in transfer efficiency. Here, the resistance value of the secondary transfer roller 15 is measured by installing the secondary transfer roller 15 on a conductive metal plate and applying a load of 4.9 N on one side (total of 9.8 N on both sides) to both ends of the core metal. It calculated from the value of the electric current which flows when a voltage of 1000 [V] is applied between the metal core and the metal plate in a state of being applied.

  The secondary transfer roller 15 is rotationally driven by a driving force (not shown), and its peripheral speed is adjusted to be substantially the same as that of the intermediate transfer belt 5. The secondary transfer is controlled by a constant current, and in this embodiment, the set value is +30 [μA]. Further, the transfer paper P as a recording medium is fed at a timing when the leading end of the four-color superimposed image on the intermediate transfer belt 5 reaches the secondary transfer position by a paper feed roller, a transfer paper transport roller, and a registration roller (not shown). The paper is fed together. The four-color superimposed image transferred onto the transfer paper P is discharged by a discharging means (not shown), then conveyed to the fixing device 50 along the fixing inlet guide, fixed, and then discharged by a discharging roller (not shown). The paper is ejected.

Further, the toner used in this embodiment is a polymerized toner produced by a polymerization method. Further, the shape factor SF-1 of the toner used in this embodiment is preferably in the range of 100 to 180, and the shape factor SF-2 is preferably in the range of 100 to 180. 3 and 4 are diagrams schematically showing the shape of the toner in order to explain the shape factor SF-1 and the shape factor SF-2, respectively. The shape factor SF-1 indicates the ratio of the roundness of the toner shape and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) 2 / AREA} × (100π / 4) Formula (1)
When the value of SF-1 is 100, the shape of the toner is a true sphere, and becomes irregular as the value of SF-1 increases.

The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner on the two-dimensional plane by the figure area AREA and multiplying by 100 / 4π.
SF-2 = {(PERI) 2 / AREA} × (100 / 4π) (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the SF-2 value increases, the unevenness of the toner surface becomes more prominent.

  Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.), introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) and analyzing it. Calculated. When the shape of the toner is close to a spherical shape, the contact state between the toner and the toner or the toner and the photosensitive drum 1 becomes a point contact, so that the adsorbing force between the toners becomes weak, and thus the fluidity becomes high. And the photosensitive drum 1 are weakened, and the transfer rate is increased. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered and the cleaning property when attached to the transfer means is also lowered, which is not preferable.

  The toner particle size is preferably in the range of 4 to 10 [μm] in terms of volume average particle size. When the particle size is smaller than this, it becomes a cause of background stains at the time of development, fluidity is deteriorated, and further, aggregation tends to occur, so that voids are likely to occur. On the other hand, when the particle size is larger than this, a high-definition image cannot be obtained due to toner scattering or resolution deterioration. In this embodiment, a toner having a volume average particle diameter of 6.5 [μm] is used.

  Hereinafter, a configuration of a blade cleaning mechanism that partially operates the intermediate transfer belt 5, which is a characteristic part of the present invention, and removes substances adhering to the belt cleaning blade 10 will be described with reference to a plurality of embodiments.

Example 1
First, Example 1 which is a first example of the blade cleaning mechanism of the intermediate transfer belt 5 according to the present embodiment will be described with reference to the drawings. FIG. 5 is an explanatory view of the configuration of the 10 blade cleaning mechanism of the belt cleaning blade of the present embodiment.

  First, a basic mechanism of a blade cleaning mechanism that applies a partial operation to the intermediate transfer belt 5 and removes substances adhering to the tip of the belt cleaning blade 10 will be described. When an operation is given to a partial section of the intermediate transfer belt 5 including a portion where the belt cleaning blade 10 abuts, the blade facing roller 14 slightly moves in the vertical direction. Thus, even if the blade facing roller 14 moves in the vertical direction, the tip of the belt cleaning blade 10 is kept in contact with the surface of the intermediate transfer belt 5. The relative position or the contact posture between the intermediate transfer belt 5 and the tip of the belt cleaning blade 10 is changed by the partial operation of the intermediate transfer belt 5. Specifically, when the blade facing roller 14 moves upward, the tip of the belt cleaning blade 10 moves upstream in the endless movement direction of the intermediate transfer belt 5, and when the blade facing roller 14 moves downward, the belt cleaning blade 10. Of the intermediate transfer belt 5 moves downstream in the endless movement direction of the intermediate transfer belt 5. If it changes in this way, even if the intermediate transfer belt 5 is not moving endlessly, the intermediate transfer belt 5 and the tip of the belt cleaning blade 10 will rub. By the friction between the intermediate transfer belt 5 and the tip of the belt cleaning blade 10, that is, friction, adhered substances such as toner and paper powder attached to the tip of the belt cleaning blade 10 can be removed. Further, since the operation applied to the intermediate transfer belt 5 is partial, a primary transfer nip portion formed by the primary transfer roller 9Y on the most upstream side in the endless movement direction of the intermediate transfer belt 5 and the photosensitive drum 1Y. In this way, it is possible to remove substances adhering to the tip of the belt cleaning member such as toner and paper dust. Since it can be removed in this way, it is possible to remove substances adhering to the tip of the belt cleaning blade 10 such as toner and paper dust during and after image formation, and the cleaning performance of the intermediate transfer belt 5 Can be suppressed.

  In this embodiment, the partial operation applied to the intermediate transfer belt 5 is a partial vibration of the intermediate transfer belt 5. Next, a specific configuration will be described with reference to FIG. As shown in FIG. 5, the blade facing roller 14 is connected to a bias applying means 101 (dedicated to the blade facing roller 14), and can apply up to 7 [kV] in this embodiment. The polarity of the bias voltage applied to the blade facing roller 14 is the same as the polarity of the secondary transfer bias voltage applied to the driving roller 7 by the bias applying unit 100. Here, when a bias voltage having a polarity opposite to the secondary transfer bias voltage applied to the drive roller 7 is applied to the blade facing roller 14, a current generated by the secondary transfer bias voltage of the drive roller 7 is applied to the secondary transfer roller 15. This is because a transfer failure is caused by flowing into the blade facing roller 14 instead.

  When a bias voltage is applied to the blade facing roller 14, the intermediate transfer belt 5 is electrostatically attracted to the blade facing roller 14, and the intermediate transfer belt 5 in which the true charge is induced is further wound around the blade facing roller 14. Become. However, the portion of the intermediate transfer belt 5 that contacts the blade facing roller 14 loses electrostatic force because the true charge induced by the contact escapes to the brush opposing roller 13, and the blade facing roller due to the tension of the intermediate transfer belt 5. 14 is moved from the state wound around 14 to the state in contact. For this reason, the intermediate transfer belt 5 vibrates because it repeats a state of being attracted and wound around the blade facing roller 14 (hereinafter referred to as an attracted state) and a state of contact (hereinafter referred to as a separated state). . Due to the vibration of the intermediate transfer belt 5, the blade facing roller 14 also slightly vibrates in the vertical direction. Further, between the blade facing roller 14 and the primary transfer roller 9K on the upstream side in the endless movement direction of the intermediate transfer belt 5, a brush facing roller 13 and a belt biasing roller 17 are disposed between the intermediate transfer belt 5 and the blade facing roller 14. A driving roller 7 is disposed downstream of the endless moving direction. Therefore, the intermediate transfer belt 5 repeats the attracted state / separated state with respect to the blade facing roller 14 and is partially subjected to vibration (operation).

  The relative position between the intermediate transfer belt 5 and the tip of the belt cleaning blade 10 is changed by the vibration applied in this manner, and the intermediate transfer belt 5 and the tip of the belt cleaning blade 10 are repeatedly rubbed. . The friction between the intermediate transfer belt 5 and the tip of the belt cleaning blade 10, that is, the friction is repeated, so that the toner or paper adhered to the tip of the belt cleaning blade 10 can be more efficiently than simply operating the intermediate transfer belt 5. Adhering substances such as powder can be removed. Therefore, it is possible to suppress the deterioration of the cleaning performance more efficiently than simply operating the intermediate transfer belt 5.

  Further, by using the electrostatic force generated by the bias voltage applied to the blade facing roller 14 as the vibration applied to a partial section of the intermediate transfer belt 5, the removal of the adhering substance on the tip of the belt cleaning blade 10 is stabilized. Can be performed.

  Further, the polarity of the bias voltage applied to the blade facing roller 14 by the bias applying means 101 and the secondary transfer bias voltage applied to the driving roller 7 by the bias applying means 100 are made the same polarity. By applying a bias voltage of such polarity to the blade facing roller 14, secondary transfer failure can be suppressed as described above.

  Further, the belt urging roller 17 is provided between the belt cleaning blade 10 and the primary transfer roller 9Y of the process unit 20Y provided on the most upstream side in the endless movement direction of the intermediate transfer belt 5. By providing the belt urging roller 17 in this manner, the belt urging roller indicates that the vibration by the blade cleaning mechanism is transmitted to the transfer nip portion formed by the primary transfer roller 9Y and the photosensitive drum 1Y. 17 can be reliably suppressed. For this reason, the removal of the substance adhering to the tip of the belt cleaning blade 10 and the image forming operation can be made compatible with each other, and the substance adhering to the tip of the belt cleaning blade 10 can be efficiently removed. . In this embodiment, as shown in FIG. 5, the belt urging roller 17 that urges the intermediate transfer belt 5 from the back surface is provided. However, the present invention is not limited to such a configuration. Alternatively, a belt urging roller that urges the intermediate transfer belt 5 from the surface may be provided.

  In this embodiment, the blade facing roller 14 is used as a means for vibrating the intermediate transfer belt 5. However, even if a nearby component that is in contact with the intermediate transfer belt 5, such as the brush facing roller 13, is used, the cleaning performance can be improved. It is possible to suppress the decrease. The bias voltage applied to the blade facing roller 14 may be always applied during operation of the printer of the present embodiment. However, when the number of images formed reaches a predetermined number, the bias voltage is applied to the blade facing roller 14. A blade cleaning mode to be applied may be provided.

(Example 2)
Example 2 which is a second example of the blade cleaning mechanism of the intermediate transfer belt 5 according to the present embodiment will be described with reference to the drawings. FIG. 6 is an explanatory diagram of the configuration of the blade cleaning mechanism of the belt cleaning blade 10 of the present embodiment. Here, the first embodiment and the present embodiment differ in the configuration relating to the point that the bias applying means to the blade facing roller 14 and the secondary transfer bias voltage applying means are the same bias applying means 100. Therefore, other similar configurations and operations will be omitted as appropriate.

  As shown in FIG. 6, in the blade cleaning mechanism of this embodiment, a bias applying unit to the blade facing roller 14 and a driving roller that also functions as a secondary transfer bias roller for transferring a toner image from the intermediate transfer belt 5 to a sheet. 7 is the same bias application means 100 as the application means to 7. By configuring the bias application means to the blade facing roller 14 in this way, it is not necessary to provide a high voltage power supply for applying the bias individually, and the communication path can be shared, so that it is lower than the first embodiment described above. It is possible to prevent the deterioration of the cleaning performance due to the cost, and it is possible to prevent the occurrence of noise due to discharge or leakage between both rollers. Further, since discharge and leakage are caused by a potential difference, if the bias voltage applied to the driving roller 7 and the blade facing roller 14 is set to the same potential, generation of noise due to discharge or leakage can be prevented more stably.

Example 3
Example 3 which is a third example of the blade cleaning mechanism of the intermediate transfer belt 5 according to the present embodiment will be described with reference to the drawings. FIG. 7 is an explanatory diagram of the configuration of the blade cleaning mechanism of the belt cleaning blade 10 of the present embodiment. Here, the first and second embodiments described above and the present embodiment differ only in the configuration relating to the point that the blade facing roller 14 is offset in the direction of the drive roller 7, so that other similar configurations and operations are used. Will be omitted as appropriate.

  As shown in FIG. 7, in the blade cleaning mechanism of this embodiment, the blade facing roller 14 is offset from the front end of the belt cleaning blade 10 toward the upstream side in the endless movement direction of the intermediate transfer belt 5, that is, the drive roller 7 side. ing. Here, in this embodiment, the offset distance is set to 0.5 [mm]. By offsetting in this way, the vibration amplitude of the intermediate transfer belt 5 increases, so that the cleaning effect of toner, paper dust, etc. adhering to the tip of the belt cleaning blade 10 can be enhanced and cleaning performance can be improved as compared with the case where offset is not performed. It is possible to suppress the decrease more efficiently.

Example 4
Example 3 which is a third example of the blade cleaning mechanism of the intermediate transfer belt 5 according to the present embodiment will be described with reference to the drawings. FIG. 8 is an explanatory diagram of the configuration of the blade cleaning mechanism of the belt cleaning blade of this embodiment. Here, the first to third embodiments described above and the present embodiment differ only in the configuration relating to the configuration in which the position of the blade facing roller 14 is not fixed but can be displaced in the vertical direction. Similar configurations and operations will be omitted as appropriate.

  As shown in FIG. 7, in the blade cleaning mechanism of this embodiment, the position of the blade facing roller 14 is not fixed but the blade facing roller 14 is pressed from the inside of the intermediate transfer belt 5 by the spring 16 and displaced in the vertical direction in the figure. This is a possible configuration. By adopting such a configuration, the blade facing roller may be used during the endless movement of the intermediate transfer belt 5 and for a while after the stop due to a change in belt tension at the time of the endless movement of the intermediate transfer belt 5 or when the speed fluctuates. 14 is displaced up and down. By displacing in this way, the contact posture of the intermediate transfer belt 5 and the cleaning blade changes, and it becomes possible to remove the adhered substances such as toner and paper dust adhered to the tip of the belt cleaning blade 10.

  Further, in this embodiment, in order to obtain an inexpensive configuration, in the configuration in which the blade facing roller 14 is pressed from the inside of the intermediate transfer belt 5 by the spring 16, the position of the blade facing roller 14 is displaced. However, the present invention is not limited to such a configuration. For example, a pulling force is applied by a spring or the like in a direction in which the blade facing roller 14 is separated from the inner side of the intermediate transfer belt 5, and a cam member or the like for rotationally driving the blade facing roller 14 against the inner side of the intermediate transfer belt 5 is added. A configuration may be used in which the blade facing roller 14 and the intermediate transfer belt 5 are displaced using a vibration member.

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)
An endless intermediate transfer belt to which a toner image on an image carrier such as the photosensitive drum 1 is transferred, and a primary provided opposite to the image carrier via an intermediate transfer belt such as an intermediate transfer belt 5. A primary transfer bias roller such as a transfer bias roller 9, a plurality of stretching rollers such as a driving roller 7 and a tension roller 8 that stretch the intermediate transfer belt, and a toner image transferred onto the intermediate transfer belt; A secondary transfer bias roller such as a driving roller 7 to which a secondary transfer bias voltage for secondary transfer onto a recording medium such as transfer paper P is applied, and a belt cleaning blade 10 that removes transfer residual toner on the surface of the intermediate transfer belt. And a cleaning cleaning member such as a blade facing roller 14 facing the belt cleaning member via the intermediate transfer belt. In an image forming apparatus comprising a roller and a means such as a drive motor that moves the intermediate transfer belt endlessly, the intermediate transfer belt is subjected to a partial operation, and the relative position between the intermediate transfer belt and the belt cleaning member; Alternatively, the contact posture is changed to remove substances such as toner and paper dust attached to the belt cleaning member.
According to this, as described in the first embodiment, the adhered substances such as toner and paper dust adhered to the belt cleaning member such as the belt cleaning blade 10 are removed during and after the image formation. Therefore, it is possible to provide an image forming apparatus such as a printer that can suppress a decrease in cleaning performance of the intermediate transfer belt such as the intermediate transfer belt 5.
(Aspect B)
In (Aspect A), the partial operation of the intermediate transfer belt such as the intermediate transfer belt 5 is a vibration.
According to this, as described in the first embodiment, a substance such as toner or paper dust adhered to a belt cleaning member such as the belt cleaning blade 10 is merely partially applied to the intermediate transfer belt such as the intermediate transfer belt 5. The removal can be performed more efficiently than the operation configuration.
(Aspect C)
In (Aspect B), the partial vibration of the intermediate transfer belt such as the intermediate transfer belt 5 is generated by applying a bias voltage to the cleaning facing roller such as the blade facing roller 14. is there.
According to this, as described in the first embodiment, when a bias voltage is applied to the cleaning counter roller such as the blade counter roller 14, an electrostatic force is generated between the intermediate transfer belt such as the intermediate transfer belt 5 and the cleaning counter roller. Occurs and the intermediate transfer belt vibrates. By using the vibration at this time to remove substances such as toner and paper dust adhered to the belt cleaning member such as the belt cleaning blade 10, it is possible to remove the adhered substances stably.
(Aspect D)
In (Aspect C), the bias voltage applied to the cleaning facing roller such as the blade facing roller 14 has the same polarity as the bias voltage applied to the secondary transfer bias roller such as the driving roller 7. It is.
According to this, as described in the first and second embodiments, secondary transfer failure can be suppressed and a high-voltage power supply need not be provided separately. It becomes possible to remove the substance adhering to the cleaning member.
(Aspect E)
In (Aspect D), the bias voltage applied to the cleaning facing roller such as the blade facing roller 14 is the same bias voltage as the bias voltage applied to the secondary transfer bias roller such as the driving roller 7. Is.
According to this, as described in the second embodiment, the bias voltage applied to the cleaning facing roller such as the blade facing roller 14 and the secondary transfer bias roller such as the driving roller 7 is made to be the same individually. Since there is no need to provide a high-voltage power supply and the risk of leakage can be reduced, it is possible to stably and inexpensively remove substances such as toner and paper dust adhering to belt cleaning members such as the belt cleaning blade 10. It becomes possible to do.
(Aspect F)
In any one of (Aspect A) to (Aspect E), a cleaning counter roller such as a blade counter roller 14 is provided offset from the belt cleaning member such as the belt cleaning blade 10. is there.
According to this, as described in the third embodiment, the vibration amplitude of the intermediate transfer belt such as the intermediate transfer belt 5 is increased, so that the tip of the belt cleaning member such as the belt cleaning blade 10 is positioned more than when the offset is not offset. The cleaning effect of substances such as adhered toner and paper dust can be enhanced, and the deterioration of the cleaning performance can be further effectively suppressed.
(Aspect G)
In (Aspect A), a partial operation of the intermediate transfer belt such as the intermediate transfer belt 5 is given by changing the position of the cleaning facing roller such as the blade facing roller 14, and the intermediate transfer belt and the belt The contact posture with the cleaning member is changed.
According to this, as described in the fourth embodiment, the position of the cleaning facing roller such as the blade facing roller 14 changes, so that the intermediate transfer belt such as the intermediate transfer belt 5 and the belt cleaning blade 10 such as the belt cleaning blade 10 are cleaned. Since the contact posture with the member can be changed, substances such as toner and paper dust attached to the belt cleaning member can be removed.
(Aspect H)
In any one of (Aspect A) to (Aspect G), the intermediate transfer belt 5 or the like is interposed between the belt cleaning member such as the belt cleaning blade 10 and the primary transfer bias roller such as the primary transfer bias roller 9. A belt urging roller such as a belt urging roller 17 that urges the intermediate transfer belt from the front surface or the back surface is provided.
According to this, as described in the first embodiment, the vibration for removing substances such as toner and paper dust attached to the tip of the belt cleaning member such as the belt cleaning blade 10 is applied to the belt such as the belt urging roller 17. Since it can be suppressed by the force roller, it is possible to achieve both the removal of substances such as toner and paper dust adhering to the belt cleaning member and the image forming operation, and the adhering to the belt cleaning member is efficiently removed. Can be performed.

DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Charging device 4 Developing device 5 Intermediate transfer belt 6 Photoconductor cleaning device 7 Drive roller 8 Tension roller 9 Primary transfer bias roller 10 Belt cleaning blade 11 Solid lubricant 12 Brush roller 12
13 Brush facing roller 14 Blade facing roller 15 Secondary transfer roller 16 Spring 17 Belt urging roller 20 Process unit 32 Intermediate transfer unit 32
50 Fixing Device 100 Bias Application Unit 101 Bias Application Unit (Dedicated to Blade Opposing Roller)
P Transfer paper

Japanese Patent Laid-Open No. 10-010939

Claims (9)

An endless intermediate transfer belt onto which the toner image on the image carrier is transferred;
A primary transfer bias roller provided opposite to the image carrier via an intermediate transfer belt;
A plurality of stretching rollers for stretching the intermediate transfer belt;
A secondary transfer bias roller to which a secondary transfer bias for secondary transfer of the toner image transferred onto the intermediate transfer belt onto a recording medium is applied;
A belt cleaning member for removing transfer residual toner on the surface of the intermediate transfer belt;
A cleaning facing roller facing the belt cleaning member via the intermediate transfer belt;
Means for endlessly moving the intermediate transfer belt;
In an image forming apparatus comprising:
By applying a bias voltage having the same polarity as that of the secondary transfer bias to the cleaning facing roller, a partial vibration is applied to the intermediate transfer belt, and the relative position between the intermediate transfer belt and the belt cleaning member or An image forming apparatus, wherein a substance attached to the belt cleaning member is removed by changing a contact posture. The image forming apparatus according to claim 1.
An image forming apparatus, wherein a bias voltage applied to the cleaning counter roller is the same as a secondary transfer bias voltage applied to the secondary transfer bias roller. The image forming apparatus according to claim 2.
The image forming apparatus, wherein the bias voltage to the cleaning counter roller and the secondary transfer bias voltage to the secondary transfer bias roller are applied by the same bias applying unit. The image forming apparatus according to any one of claims 1 to 3,
An image forming apparatus, wherein the cleaning counter roller is offset with respect to the belt cleaning member. An endless intermediate transfer belt onto which the toner image on the image carrier is transferred;
A primary transfer bias roller provided opposite to the image carrier via an intermediate transfer belt;
A plurality of stretching rollers for stretching the intermediate transfer belt;
A secondary transfer bias roller to which a secondary transfer bias for secondary transfer of the toner image transferred onto the intermediate transfer belt onto a recording medium is applied;
A belt cleaning member for removing transfer residual toner on the surface of the intermediate transfer belt;
A cleaning facing roller facing the belt cleaning member via the intermediate transfer belt;
Means for endlessly moving the intermediate transfer belt;
In an image forming apparatus comprising:
The cleaning counter roller is offset from the belt cleaning member,
By applying a bias voltage to the cleaning counter roller, the intermediate transfer belt is partially vibrated, and the relative position between the intermediate transfer belt and the belt cleaning member or the contact posture is changed. An image forming apparatus for removing a substance adhering to a belt cleaning member. The image forming apparatus according to any one of claims 1 to 5,
An image forming apparatus comprising a belt urging roller for urging the intermediate transfer belt from the front surface or the back surface between the belt cleaning member and the primary transfer bias roller. The image forming apparatus according to any one of claims 1 to 6,
An image forming apparatus comprising a driving roller for driving the intermediate transfer belt on the upstream side of the belt cleaning member in the moving direction of the intermediate transfer belt. The image forming apparatus according to claim 7.
The image forming apparatus, wherein the driving roller is the secondary transfer bias roller. The image forming apparatus according to any one of claims 1 to 8,
An image forming apparatus having a blade cleaning mode in which a bias voltage is applied to the cleaning counter roller when the number of formed images reaches a predetermined number .

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