JP2010026348A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain good cleaning performance by always keeping a contact pressure within a proper range and to improve durability by equalizing the contact pressure in a breadthwise direction without spoiling maintainability to suppress local wear of a cleaning blade, in an image forming apparatus including a cleaning device for belt-like image carrier. <P>SOLUTION: In a cleaning device 17 wherein a cleaning blade 1 is brought into contact with a surface of an intermediate transfer belt 10 to remove toner, the cleaning blade is fixedly disposed in the cleaning device, and a counter roller 19 facing the abutment part of the cleaning blade with the intermediate transfer belt therebetween is provided in an inner peripheral part of the intermediate transfer belt, and the intermediate transfer belt is biased from the inner peripheral side by the counter roller so as to increase a pressing force in a normal direction of the abutment part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer, and more particularly to an image forming apparatus that employs a cleaning device that cleans the surface of a belt-like image carrier.

  2. Description of the Related Art Conventionally, a blade type cleaning device that removes toner by bringing a cleaning blade into contact with the surface of an image carrier is widely known. In the blade type cleaning device, if the contact pressure of the cleaning blade to the image carrier is high, high cleaning performance can be exhibited in the initial stage. Cleaning performance will decrease. On the other hand, if the contact pressure is low, the adhesion between the image carrier and the cleaning blade cannot be ensured, resulting in poor cleaning particularly in a low temperature environment. For this reason, it is desired to always maintain the contact pressure between the cleaning blade and the image carrier in an appropriate range.

  A blade-type cleaning device that fixes and supports one end of the blade holder that holds the cleaning blade with a device housing so that the cleaning blade tip is brought into contact with the fixed image carrier with a predetermined contact pressure. It has been known. In this cleaning device, since the positional relationship between the cleaning blade and the image carrier is fixed, the contact state between the image carrier and the cleaning blade is reduced due to film abrasion of the image carrier or wear of the cleaning blade. If it changes, the contact pressure between the cleaning blade and the image carrier varies with respect to the initial set value, and it is difficult to maintain it in an appropriate range.

  In addition, there is known a technique in which a cleaning blade can be displaced in a cleaning device to suppress fluctuations in contact pressure with an image carrier (for example, Patent Document 1). For example, in the cleaning device shown in FIG. 6, the plate-like blade holder that holds the cleaning blade is rotatable about a support shaft, and the image carrier is urged by a spring to fix the cleaning blade. Abut. With such a configuration, even when the contact state between the image carrier and the cleaning blade changes, the cleaning blade rotates to suppress fluctuations in the contact pressure with the image carrier.

Japanese Patent No. 3958013

  However, in the case where the blade holder in FIG. 6 is pressed by a spring, the blade holder in the vicinity of the pressurizing portion may bend and a deviation in contact pressure may occur in the width direction. Where the contact pressure is strong in the width direction, the wear of the cleaning blade progresses faster than other areas over time, and the cleaning failure first appears, leaving an area where the cleaning performance can be fully demonstrated. Regardless, it will end its life at this point.

  In order to reduce the deflection, it is conceivable to increase the size of the blade holder for the purpose of increasing the rigidity of the blade holder, but this increases the weight of the cleaning device. For this reason, the maintenance performance at the time of attachment / detachment is impaired by a cleaning device having a relatively high replacement frequency.

  The present invention has been made in view of the above background, and an object of the present invention is to provide an image forming apparatus including a cleaning device that removes toner by bringing a cleaning blade into contact with the surface of a belt-shaped image carrier. Maintaining the contact pressure within an appropriate range to obtain good cleaning performance, and uniformizing the contact pressure in the width direction without impairing maintainability, suppressing local wear of the cleaning blade and improving durability An object of the present invention is to provide an image forming apparatus that can be improved.

In order to achieve the above object, a first aspect of the present invention is a belt-like image carrier that carries a toner image and moves on the surface, and a cleaning that removes toner by bringing a cleaning blade into contact with the surface of the image carrier. In the image forming apparatus, the cleaning blade is fixedly disposed in the cleaning device, and is opposed to the inner peripheral portion of the image carrier with the contact portion of the cleaning blade and the image carrier interposed therebetween. The counter roller is provided to bias the image carrier from the inner peripheral side so as to increase the pressing force in the normal direction of the corresponding contact portion.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect of the present invention, a pressurizing unit that pressurizes the counter roller toward the contact portion is provided on an inner peripheral portion of the image carrier. To do.
According to a third aspect of the present invention, in the image forming apparatus of the first aspect, the counter roller is provided vertically above the contact portion with the cleaning blade, and the counter roller causes the image carrier to move to the inner periphery by its own weight. It is characterized by energizing from the side.
According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first, second, and third aspects, the opposing roller faces the inner side of the image carrier so as to separate the image carrier from the cleaning blade. And is movable.
According to a fifth aspect of the present invention, there is provided the image forming apparatus according to the second or fourth aspect, wherein the pressurizing unit is configured so that both end portions of the counter roller are positioned at positions corresponding to outside the image forming area in the width direction of the image carrier. Each pressurizing unit is characterized in that both end portions of the opposing roller can be independently displaced.
According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first, second, third, fourth, and fifth aspects, the average circularity of the toner used is 0.90 to 0.99. To do.
According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first, second, third, fourth, fifth or sixth aspect, the shape factor SF-1 of the toner used is 120 to 180, and the shape factor SF -2 is 120 to 190.
The invention according to claim 8 is the image forming apparatus according to any one of claims 1, 2, 3, 4, 5, 6 or 7, wherein the volume average particle diameter of the toner used is Dv (μm), and the number average particle When the diameter is Dn (μm), Dv / Dn is 1.05 to 1.30.

  In the present invention, since the image carrier is biased by the opposing roller so as to increase the pressing force in the normal direction of the contact portion between the cleaning blade and the image carrier, the gap between the image carrier and the cleaning blade is Even when the contact state changes, the image carrier is displaced to suppress a change in contact pressure. In addition, the roller-shaped member has a shape that makes it easier to obtain rigidity than the plate-shaped member, and even if the rigidity of the opposing roller disposed on the inner peripheral portion of the image carrier is increased, the weight of the cleaning device is affected. There is nothing. Therefore, it is easier than the conventional structure in which the pressing force of the abutting portion is increased by urging the plate-shaped blade holder by urging the pressing force of the abutting portion with the opposing roller. Therefore, the deviation of the contact pressure in the width direction can be suppressed. Thereby, local abrasion of the cleaning blade is suppressed and durability can be improved.

  As described above, according to the present invention, in the image forming apparatus provided with the cleaning device that removes the toner by bringing the cleaning blade into contact with the surface of the belt-shaped image carrier, the contact pressure is always maintained within an appropriate range. There is an excellent effect that the cleaning performance can be obtained and the durability of the cleaning blade can be improved by suppressing the deviation of the contact pressure in the width direction without impairing the maintainability, thereby suppressing the local abrasion of the cleaning blade.

Hereinafter, an embodiment in which the present invention is applied to an image forming apparatus will be described. First, the configuration and operation of the image forming apparatus according to the present embodiment will be described.
FIG. 1 is a schematic configuration diagram of the entire image forming apparatus according to the present embodiment. In FIG. 1, reference numeral 100 denotes a tandem intermediate transfer type electrophotographic apparatus main body as an image forming apparatus, and 200 denotes a paper feed table on which the electrophotographic apparatus main body is placed. Subscripts Y, M, C, and K indicate yellow, cyan, magenta, and black (black) colors, respectively. Other reference numerals are directly referred to in the following description.

  The main body 100 is provided with an endless belt-like intermediate transfer belt 10 as an image carrier near the center. The intermediate transfer belt 10 is movable around the plurality of rollers 14, 15, 15 ′, 16, 19 and moved in the clockwise direction in the drawing. In FIG. 1, a cleaning device 17 for the intermediate transfer belt is provided on the left side of the roller 19. The cleaning device 17 removes residual toner remaining on the intermediate transfer belt 10 after image transfer.

  On the intermediate transfer belt 10 stretched between the rollers 14 and 15, four image forming units 18Y, 18M, 18C and 18K (hereinafter referred to as 18Y, yellow, cyan, magenta and black) are arranged along the surface movement direction. The abbreviations such as M, C, and K.) are arranged side by side to constitute the tandem image forming apparatus 20. An exposure device 21 is provided on the tandem image forming apparatus 20.

  Each image forming unit 18 of the tandem image forming apparatus 20 includes drum-shaped photoconductors 40Y, M, C, and K that carry toner images of colors of yellow, cyan, magenta, and black. Further, at the primary transfer position at which the toner image is transferred from the photoreceptors 40Y, 40M, 40C, and 40K to the intermediate transfer belt 10, the photoreceptors 40Y, M, C, and K are opposed to each other with the intermediate transfer belt 10 interposed therebetween. As described above, primary transfer rollers 62Y, 62M, 62C, and 62K are provided as components of the primary transfer unit. The roller 14 is a drive roller that rotationally drives the intermediate transfer belt 10. When a black monochrome image is formed on the intermediate transfer belt 10, the rollers 15 and 15 ′ other than the driving roller are moved to separate the yellow, cyan, and magenta photoreceptors 40 Y, M, and C from the intermediate transfer belt 10. It is also possible.

 A secondary transfer device 22 is provided on the opposite side of the intermediate transfer belt 10 from the tandem image forming device 20. In the illustrated example, the secondary transfer device 22 presses the secondary transfer roller 16 'against the secondary transfer counter roller 16 to apply a transfer electric field, thereby transferring the image on the intermediate transfer body 10 to a sheet (not shown) as transfer paper. Transcript. A fixing device 25 for fixing the transfer image on the sheet is provided beside the secondary transfer device 22. The fixing device 25 is configured by pressing a pressure roller 27 against a fixing belt 26 that is an endless belt. The sheet after image transfer is conveyed to the fixing device 25 by the conveyance belt 24. In the illustrated example, under such a secondary transfer device 22 and a fixing device 25, a sheet reversing device 28 for reversing the sheet so as to record images on both sides of the sheet in parallel with the tandem image forming device 20 described above. Is provided.

  When image data is sent to the image forming apparatus 100 and a signal for starting image formation is received, the roller 14 is driven to rotate by a drive motor (not shown), and the other rollers 15, 15 ', 16, 19 are driven to rotate. The transfer belt 10 is rotated and conveyed. At the same time, a single color image of yellow, cyan, magenta, and black is formed on each photoconductor 40 by the individual image forming means 18. Then, along with the movement of the surface of the intermediate transfer belt 10, those single color images are sequentially transferred by the primary transfer rollers 62 Y, M, C, and K to form a composite color image on the intermediate transfer body 10.

  Further, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, the sheets are fed out from one of the paper cassettes 44 provided in multiple stages in the paper bank 43, and are separated one by one by the separation roller 45 and fed. The paper is put into a path 46, transported by a transport roller 47, led to a paper feed path 48 in the copying machine main body 100, and abutted against a registration roller 49 and stopped. Alternatively, the sheet feed roller 50 is rotated to feed out the sheets on the manual feed tray 51, separated one by one by the separation roller 52, put into the manual feed path 53, and abutted against the registration roller 49 and stopped. Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer belt 10, the sheet is fed between the intermediate transfer belt 10 and the secondary transfer device 22, and transferred by the secondary transfer device 22. A color image is recorded on the sheet. The sheet after the image transfer is conveyed by the secondary transfer device 22 and sent to the fixing device 25, the transfer image is fixed by applying heat and pressure, and then discharged by the discharge roller 56. Stack on top. Alternatively, it is switched by a switching claw (not shown) and put into the sheet reversing device 28, where it is reversed and guided again to the transfer position, and an image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56. . On the other hand, the intermediate transfer belt 10 after the image transfer is removed by the intermediate transfer belt cleaning device 17 to remove residual toner remaining on the intermediate transfer belt 10 after the image transfer, and the tandem image forming apparatus 20 forms an image again. Prepare.

  Next, the cleaning device 17 for the intermediate transfer belt, which is a characteristic part of this embodiment, will be described. FIG. 2 is a schematic configuration diagram of a contact portion between the cleaning device 17 and the intermediate transfer belt 10. The cleaning device 17 is disposed in the opening facing the intermediate transfer belt 10 at the upstream side of the cleaning blade 1 made of urethane rubber for removing the toner remaining on the intermediate transfer belt 10, and the surface of the intermediate transfer belt 10. A cleaning brush 2 that rotates in the moving direction and the counter direction is provided. By disposing the cleaning brush 2 on the upstream side of the cleaning blade 1, foreign matters such as paper dust are prevented from entering the cleaning blade 1 and have a function as a cleaning auxiliary member.

  The cleaning blade 1 is supported by the housing 4 of the cleaning device 17, and is fixedly disposed in the cleaning device 17 so that the tip abuts against the surface of the intermediate transfer belt 10 facing the roller 19. That is, the roller 19 that supports the intermediate transfer belt 10 has a function as a counter roller of the cleaning blade 1, and is hereinafter referred to as a counter roller 19.

  A pressing means is provided to press the opposing roller 19 toward the contact portion that contacts the cleaning blade 1, and the opposing roller 19 applies a pressing force in the normal direction of the contact portion from the inner peripheral side of the intermediate transfer belt 10. Energize to increase. As a pressing means, both end shaft portions 19a of the opposing roller 19 are pressed by the spring 5 through the bearing member 5a. In this manner, the spring 5 biases the counter roller 19 toward the cleaning blade 1 fixed in the cleaning device 17 with the intermediate transfer belt 10 interposed therebetween, so that the cleaning blade 1 and the intermediate transfer belt 10 come into contact with each other. Even if the state changes, the intermediate transfer belt 10 is displaced so that the contact pressure is suppressed from changing. Thereby, the stable contact pressure is maintained. Further, the counter roller 19 is rarely replaced, and there is no possibility of impairing maintenance, so that the degree of freedom in design is high, and the rigidity is easily increased as compared with a plate-shaped holder conventionally used for supporting the cleaning blade 1. Therefore, it is difficult for the bending to occur as compared with the case where the holder is biased to suppress the variation of the contact pressure. Specifically, a SUS roller or an aluminum roller having a diameter of 20 to 40 mm can be used as the counter roller 19, and bending due to pressure hardly occurs. Therefore, the cleaning blade 1 is less likely to generate a contact pressure deviation in the width direction, can suppress local wear, and can improve durability.

  On the other hand, in the case of pressing the holder 3 of the conventional cleaning blade 1, a steel plate having a thickness of about 1.0 to 2.0 mm is generally used as the blade holder. It is desirable that the cleaning device 17 be smaller and lighter in consideration of exchangeability and maintainability. Further, a blade holder having such a thickness is used to reduce the cost required for replacement. . In the case where the holder 3 is pressurized by the spring 5 and the cleaning blade 1 is brought into contact with the intermediate transfer belt with a pressure contact force of about 0.1 to 0.3 N / cm, the holder 3 is spring 5 as shown in FIG. Deflection has occurred around the pressurizing part, and a deviation has occurred in the contact pressure over the blade width direction. FIG. 7 shows a simulation of the amount of bending of the holder 3. In order to solve such a deviation of the contact pressure, it is conceivable to increase the size of the holder 3 to increase the rigidity. However, the weight of the cleaning device 17 is increased, and maintenance performance such as detachment of the cleaning device is increased. Will be damaged.

  On the other hand, the opposing roller 19 which is a roller shape of this embodiment can easily realize high rigidity. Further, even if the size of the opposing roller 19 is increased so as to increase the rigidity, the weight of the cleaning device 17 is not affected. The cleaning device 17 is replaced relatively frequently with a predetermined number of lifetimes, but even in such a case, there is no risk of impairing the maintainability when the cleaning device 17 is attached or detached.

  FIG. 3 shows the contact pressure to the intermediate transfer belt 10 in the width direction of the cleaning blade 1 when the holder of the cleaning blade 1 is pressed and when the counter roller 19 is pressed. As shown in FIG. 3, when the opposing roller 19 is pressed, the deviation in the blade width direction can be reduced as compared with the case where the holder is pressed.

  Furthermore, by arranging the spring 5 as the pressing means on the inner peripheral portion of the intermediate transfer belt 10, the space on the inner peripheral portion of the intermediate transfer belt 10 can be used effectively. Therefore, stable cleaning performance can be obtained without increasing the size of the apparatus. Further, by providing the pressurizing unit on the intermediate transfer belt 10 side instead of the cleaning device 17 side, it is possible to reduce the cost without replacing the pressurizing unit even when the cleaning device 17 is replaced.

  It is desirable that the facing roller 19 can be pressed independently at both ends 19a. As a result, both end portions can be independently displaced in the pressurizing direction, so that the opposing roller 19 can abut against the cleaning blade 1 in parallel, and a more uniform abutment pressure can be achieved across the cleaning blade width direction. can do.

  Further, in the conventional method as shown in FIG. 6, when the cleaning blade 1 is pressed against and brought into contact with the fixed opposing roller 19, it is opposed to the cleaning blade 1 with the fixed rotation fulcrum and the applied pressure. A pressure is applied to the roller 19. In this case, since the cleaning blade 1 contacts the fixed counter roller 19 by rotating around the fixed fulcrum, it is inevitable that the cleaning blade 1 contacts the counter roller 19 obliquely within a range of component variations. It was.

  On the other hand, in the case where the pressure is independently applied by the springs 5 at both ends of the opposing roller 19 as in the present embodiment, even if the cleaning blade 1 is inclined in the range of component variations, it follows this. The opposing roller 19 can abut against the cleaning blade 1 in parallel. Further, the position where the spring 5 presses the opposing roller is a portion corresponding to the outside of the image forming area on the intermediate transfer belt 10 to prevent the image transferred onto the intermediate transfer belt 10 from being disturbed.

  Further, the counter roller 19 is movable to the inner peripheral side of the intermediate transfer belt 10 so that the intermediate transfer belt 10 and the cleaning blade 1 can be separated from each other. When the cleaning device 17 is replaced, the opposing roller 19 is moved to the inner peripheral side of the intermediate transfer belt 10 to separate the intermediate transfer belt 10 from the cleaning blade 1 so that the cleaning device 17 is not pressurized. . By setting the depressurized state, the cleaning device 17 can be easily detached while maintaining the same posture as in use. Thereby, it is possible to prevent the toner collected in the cleaning device 17 from being scattered or dropped to the outside of the cleaning device 17 when the cleaning device 17 is tilted and detached. That is, high maintainability can be provided. The depressurization mechanism can be configured using a lever and a cam. However, this can be easily arranged on the inner peripheral portion of the intermediate transfer belt 10, and even when such a depressurization mechanism is provided, the apparatus is Does not increase in size.

  Next, a modification of this embodiment is shown. FIG. 5 is a schematic configuration diagram of a contact portion between the cleaning device and the intermediate transfer belt according to the modification. In the modified example, as shown in FIG. 5, the counter roller 19 is provided vertically above the contact portion of the cleaning blade 1, and the contact portion method is applied from the inner peripheral side of the intermediate transfer belt 10 by the weight of the counter roller 19. It is energized to increase the pressing force in the linear direction. In this case, the pressurizing means is unnecessary and the cost can be reduced. As shown in FIG. 2, when the spring 5 is used for urging by the counter roller 19, the contact pressure may vary due to variations in the mounting position of the spring 5, so it is necessary to set the pressure in consideration of the variation range. is there. On the other hand, when the urging is performed by the weight of the opposing roller 19 as in the modified example, the variation in the contact pressure can be more easily eliminated, and stable cleaning performance can be exhibited. As shown in FIG. 8, the cleaning blade 1 is brought into contact with the intermediate transfer belt 10 so that the contact angle is in the range of 70 ° to 90 °, and the opposing roller 19 is placed above the contact portion in the vertical direction. It is also possible to urge the contact roller 19 so as to increase the pressing force in the normal direction of the contact portion from the inner peripheral side of the intermediate transfer belt 10 by its own weight. By setting such a contact angle, good cleaning performance can be obtained.

  Note that the above-described Patent Document 1 describes a device in which a cleaning blade is movable with respect to a cleaning device, and tension is applied to a belt-like image carrier by a counter roller. In this apparatus, the cleaning device is set with the counter roller shaft as a reference position, the position of the cleaning device with respect to the counter roller is relatively unchanged, and the counter roller does not apply pressure to the cleaning blade. A pressure is applied to the opposing roller by a pressure spring on the cleaning blade side. This point is fundamentally different from that in which the cleaning blade 1 of the present embodiment is fixedly arranged and the opposing roller 19 applies pressure to the cleaning blade 1.

  Next, a toner that is preferably used in the image forming apparatus according to the embodiment will be described. Since the cleaning device 17 can achieve high removal performance, it can be put to practical use for removing toner having an average circularity of 0.90 to 0.99. The toner having a high degree of circularity is easily affected by the lines of electric force on the surface of the developing roller, and is developed faithfully along the lines of electric force of the electrostatic latent image. Therefore, when reproducing minute latent image dots, fine line reproducibility is enhanced because it is easy to obtain a dense and uniform toner arrangement. In addition, toner with a high degree of circularity has a smooth and moderate fluidity, so it is easily affected by the lines of electric force and easily transfers faithfully along the lines of electric force. A quality image can be obtained. When the average circularity of the toner is less than 0.90, faithful development and transfer with a high transfer rate cannot be performed. This is because when the toner is irregularly shaped, the toner surface is non-uniformly charged, and the center of gravity and the center of the charge are shifted, making it difficult to move faithfully to the electric field.

The toner preferably has a shape factor SF-1 in the range of 120 to 180 and a shape factor SF-2 in the range of 120 to 190.
9A and 9B are diagrams schematically showing the shape of the toner, and FIG. 9A is an explanatory diagram for explaining the shape factor SF-1, and FIG. These are explanatory drawings for explaining the shape factor SF-2.
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 toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4. When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases.
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)
Further, the shape factor SF-2 indicates the ratio of unevenness in 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 100π / 4. When the value of SF-2 is 100, unevenness does not exist on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent.
SF-2 = {(PERI) ² / AREA} × (100π / 4) (2)
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 with the toner becomes a point contact, so that the attractive force between the toners becomes weak, resulting in high fluidity, and the attractive force between the toner and the image carrier is reduced. It becomes weaker, the transfer rate becomes higher, and the residual toner on the surface of the image carrier can be easily cleaned. As SF-1 and SF-2 become larger, the shape becomes indeterminate, the toner charge amount distribution becomes wider, the development becomes less faithful to the latent image, and the transfer becomes less faithful to the transfer electric field and the image quality. Decreases. For this reason, SF-1 preferably does not exceed 180, and SF-2 preferably does not exceed 190.

  As the toner having a substantially spherical shape as described above, a toner composition containing a polyester prepolymer having a functional group containing a nitrogen atom, a polyester, a colorant, and a release agent is crosslinked in an aqueous medium in the presence of resin fine particles. A toner obtained by an extension reaction is preferred. The conventional pulverized toner manufacturing method cannot be manufactured by comparing with any of the values of circularity, average particle size, shape factor SF-1 and SF-2, and can be obtained by a polymerization method in terms of manufacturing cost and yield. Toner is superior. However, among the toners obtained by the polymerization method, the toner shape obtained by the suspension polymerization method or the emulsion polymerization method can obtain a true spherical toner in the circularity and the shape factors SF-1 and SF-2. difficult. In particular, although the toner obtained by the dissolution suspension method is spherical, it is an irregularly shaped toner having no regularity, so that satisfactory quality in terms of image quality and the like cannot be obtained.

  The ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) of the toner is preferably in the range of 1.05 to 1.30. The closer (Dv / Dn) is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution becomes uniform, and a high-quality image with little background fogging can be obtained. In the electrostatic transfer method, the transfer rate is increased. Can do.

As described above, according to the present embodiment, the cleaning blade 17 removes the toner by bringing the cleaning blade 1 into contact with the intermediate transfer belt 10 as a belt-like image carrier that carries a toner image and moves on the surface. Reference numeral 1 is fixedly disposed in the cleaning device 17 so as to increase the pressing force in the normal direction of the contact portion from the inner peripheral side by the opposing roller 19 that faces the cleaning blade 1 and the intermediate transfer belt 10 therebetween. Energize. In this apparatus, the opposing roller 19 urges the pressing force in the normal direction of the contact portion between the cleaning blade 1 and the intermediate transfer belt 10 to increase the force between the intermediate transfer belt 10 and the cleaning blade 1. Even when the contact state changes, fluctuations in the contact pressure can be suppressed. In addition, the roller-shaped member has a shape that is easy to obtain rigidity compared to the plate-shaped member. Even if the rigidity of the opposing roller 19 disposed on the inner peripheral portion of the intermediate transfer belt 10 is increased, the weight of the cleaning device 17 is not enough. There is no impact. Therefore, by adopting a configuration in which the opposing roller 19 is urged to increase the pressing force of the abutting portion, compared to a configuration in which the pressing force of the abutting portion is increased by urging the conventional plate-shaped blade holder, The deflection of the contact pressure in the width direction can be suppressed easily by reducing the deflection. Thereby, local abrasion of the cleaning blade 1 is suppressed and durability can be improved.
Further, by providing the spring 5 as a pressurizing means for urging the facing roller 19 toward the contact portion with the cleaning blade 1 on the inner peripheral portion of the intermediate transfer belt 10, the space of the apparatus can be saved. Further, since it is not necessary to replace the spring when the cleaning device 17 is replaced, the cost can be reduced.
Further, the counter roller 19 is provided vertically above the contact portion of the cleaning blade 1 so that the pressing force in the normal direction of the contact portion from the inner peripheral side of the intermediate transfer belt 10 is increased by the weight of the counter roller 19. To force. In this apparatus, the spring 5 as the pressurizing means is unnecessary, and the cost can be reduced. Further, stable cleaning performance can be exhibited regardless of variations in the attachment position of the spring 5 or the like.
Further, the counter roller 19 is movable to the inner peripheral side of the intermediate transfer belt 10 so that the intermediate transfer belt 10 and the cleaning blade 1 can be separated from each other. When the cleaning device 17 is replaced, the counter roller 19 is moved so that the intermediate transfer belt 10 is separated from the cleaning blade 1 and the pressure is not applied to the cleaning device 17. By setting the depressurized state, it can be easily detached in the same posture as in use. Thereby, it is possible to prevent the toner collected in the cleaning device from being scattered or dropped to the outside of the cleaning device 17 when the cleaning device 17 is tilted and detached.
Further, the opposing roller 19 is pressurized independently at both ends 19a, and both ends can be independently displaced in the pressure direction. Thereby, the opposing roller 19 can be brought into contact with the cleaning blade 1 in parallel, and a more uniform contact pressure can be achieved across the width of the cleaning blade. Further, the position where the spring 5 presses the opposing roller is a portion corresponding to the outside of the image forming area on the intermediate transfer belt 10 to prevent the image transferred onto the intermediate transfer belt 10 from being disturbed.
Further, by using a toner having an average circularity of 0.90 to 0.99, the reproducibility is good, the transfer rate is high, and a high quality image can be obtained.
Further, by using a toner having a shape factor SF-1 of 120 to 180 and a shape factor SF-2 of 120 to 190, a high-quality image can be obtained.
Further, when the volume average particle diameter of the toner to be used is Dv and the number average particle diameter is Dn (μm), Dv / Dn is 1.05 to 1.30, so that the toner charge amount distribution is uniform. Thus, a high-quality image with little background fogging can be obtained, and the transfer rate can be increased.

1 is a schematic configuration diagram of an entire image forming apparatus according to an exemplary embodiment. FIG. 3 is a schematic configuration diagram of a contact portion between a cleaning device and an intermediate transfer belt. The graph showing the contact pressure in the width direction of a cleaning blade. Explanatory drawing of the bending which generate | occur | produces when pressurizing the conventional holder. FIG. 10 is a schematic configuration diagram of a contact portion between a cleaning device and an intermediate transfer belt according to a modified example. Schematic block diagram of a conventional cleaning device. The figure which shows the result of having simulated the holder deflection amount with the conventional cleaning apparatus. FIG. 10 is a schematic configuration diagram of a contact portion between a cleaning device and an intermediate transfer belt according to a modified example. FIG. 6A is a diagram schematically illustrating the shape of a toner in order to explain the shape factor SF-1, and FIG. 5B is a diagram illustrating the shape factor SF-2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cleaning blade 2 Cleaning brush 3 Holder 4 Housing 5 Spring 5a Bearing part 10 Intermediate transfer belt 17 Cleaning device 18 Image forming means 19 Opposing roller 19a Shaft part 20 Tandem type image forming apparatus 40 Photoconductor

Claims (8)

A belt-like image carrier that carries a toner image and moves on the surface;
In an image forming apparatus provided with a cleaning device that removes toner by bringing a cleaning blade into contact with the surface of the image carrier,
The cleaning blade is fixedly disposed in the cleaning device, and an opposing roller is provided on the inner periphery of the image carrier so as to face the contact portion of the cleaning blade with the image carrier interposed therebetween. An image forming apparatus, wherein the image bearing member is urged from an inner peripheral side so as to increase a pressing force in a normal direction of a corresponding contact portion.   2. The image forming apparatus according to claim 1, wherein a pressing means for pressing the opposing roller toward the contact portion is provided on an inner peripheral portion of the image carrier.   2. The image forming apparatus according to claim 1, wherein the counter roller is provided vertically above a contact portion with the cleaning blade, and the counter roller urges the image carrier from its inner peripheral side by its own weight. Image forming apparatus.   4. The image forming apparatus according to claim 1, wherein the counter roller is movable toward the inside of the image carrier so as to separate the image carrier from the cleaning blade. Image forming apparatus.   5. The image forming apparatus according to claim 2, wherein the pressurizing unit pressurizes both ends of the counter roller at positions corresponding to the outside of the image forming region in the width direction of the image carrier. An image forming apparatus, wherein both end portions of the roller can be independently displaced.   6. The image forming apparatus according to claim 1, wherein the toner used has an average circularity of 0.90 to 0.99.   7. The image forming apparatus according to claim 1, wherein the toner has a shape factor SF-1 of 120 to 180 and a shape factor SF-2 of 120 to 190. An image forming apparatus.   8. The image forming apparatus according to claim 1, wherein the volume average particle size of the toner used is Dv (μm) and the number average particle size is Dn (μm). , Dv / Dn is 1.05-1.30.