JP2007047400A - Cleaning device and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning device in which contact pressure is arbitrarily determined without depending on a set angle or an intrusion depth of a blade even when a spheric toner is used for forming an image, vibration of a blade along a traveling direction of a secondary transfer roller is not inhibited, cleaning failure such as body contact or turning up of the blade is prevented and a preferable cleaning effect is obtained. <P>SOLUTION: A blade cleaning system is employed in which only the top end of a blade 70 is pressurized by an activating member such as a spring 72 or an elastic body. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cleaning device used in an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile, and an image forming apparatus using the same.

  FIG. 7 shows an example of a schematic configuration of an image forming apparatus in an electrophotographic system using an intermediate transfer belt. The image forming apparatus feeds the transfer material S loaded on the feeding cassette 20 disposed in the lower part of the apparatus by the feeding roller 21. Thereafter, the fed transfer material S is separated one by one by the retard roller pair 22 and then conveyed to the registration roller pair 24 by the conveyance roller 23. When the transfer material S reaches the registration roller pair 24, the registration roller pair 24 stops rotating. For this reason, the transfer material S is first conveyed by abutting against the nip portion of the roller pair 24 to correct the skew of the front end portion and then conveyed.

  On the other hand, in the process cartridges (image forming portions) P of the respective colors having the photosensitive drums 26 (26Y, 26M, 26C, and 26Bk) as image bearing members until the transfer material S is conveyed from the registration roller pair 24, An image is formed with toner. The image forming process will be described.

  In the case of a four-drum full color system as shown in FIG. 7, four process cartridges PY, PM, PC, and PBk of yellow, magenta, cyan, and black are arranged in parallel. An optical scanning system 28 (28Y, 28M, 28C, 28Bk) that exposes each process cartridge 26 with a laser or an LED is disposed above each process cartridge 26.

  With this configuration, when an image signal is transmitted to the image forming apparatus, first, exposure by a laser or the like is performed from the optical scanning system 28, and the electrostatic charge is electrostatically applied on the photosensitive drum 26 uniformly charged by the charger 50. A latent image is formed. Then, in the process cartridge P, the latent image on the photosensitive drum 26 is developed by the developing device 51, and a toner image of each color is formed on the photosensitive drum. Next, the toner image formed on the photosensitive drum 26 is electrically transferred onto the intermediate transfer belt 30 by the primary transfer rollers 52 (52Y, 52M, 52C, 52Bk) facing each other with the intermediate transfer belt 30 therebetween. The primary transfer is sequentially performed every time, and a multiple image is formed on the intermediate transfer belt 30. The transfer residual toner on the photosensitive drum is cleaned by the photosensitive member cleaning device 53.

  The multiple images formed on the intermediate transfer belt 30 are conveyed to the nip portion between the transfer counter roller 108 and the secondary transfer roller 27. At the same time, the transfer material S whose skew has been corrected by the above-described registration roller pair 24 is conveyed to the nip portion, and the multiple images are transferred onto the transfer material S. At this time, the toner that is not transferred and remains on the intermediate transfer belt 30 is cleaned by an intermediate transfer belt cleaning device 32 that is disposed so as to contact the intermediate transfer belt 30.

  After that, the transfer material is heated and pressed in the fixing device 25 to fix the multiple images. The transfer material is placed above the image forming apparatus 1 by the discharge roller pair 29 (29a, 29b). It is discharged to the discharge tray.

  FIG. 8 is an enlarged view of the photoconductor cleaning device 53 of the process cartridge P. A cleaning device 53 is arranged close to the photosensitive drum 26 provided as an image carrier that extends in the direction of the central axis O perpendicular to the paper surface and rotates in the direction of the arrow. The cleaning device 53 is provided with a cleaning blade 61, and the tip 61 a of the cleaning blade 61 comes into pressure contact with the surface of the photosensitive drum 26, and residual toner T generated at the transfer site and arriving at the cleaning device 53 is removed. Remove by scraping. The toner T thus scraped off is guided by the scooping sheet 62 and reaches the toner storage portion 66a in the housing 66 of the cleaning device 53, and then discharged to the outside by the conveying screw 63.

  As a method of supporting the cleaning blade 61 with respect to the photosensitive drum 26, as a widely used method, a support portion 65 of the cleaning blade 61 is fixed to a housing 66 with a blade fixing screw 64 as shown in FIG. The position of the blade 61 is completely fixed with respect to the position of the central axis O of the photosensitive drum 26. Cleaning is performed by keeping the distance between the surface of the photosensitive drum 26 and the support portion 65 of the cleaning blade 61 at a predetermined value.

  More specifically, when a material having elasticity such as urethane rubber is used for the cleaning blade 61, the cleaning blade 61 is deformed in the vicinity of the contact position with the photosensitive drum 26, and the photosensitive member is caused by the elastic force of the rubber itself. It is pressed against the drum 26. When it is assumed that the cleaning blade 61 does not cause elastic deformation (that is, it is a rigid body), the distance that has entered from the surface of the photosensitive drum 26 in the direction of the central axis O is referred to as an intrusion amount d, and the cleaning blade 61 at this time When the physical property value and shape of the cleaning blade 61 are constant, the contact pressure on the surface of the photosensitive drum 26 is substantially determined by the penetration amount d and the set angle Θ. Therefore, by maintaining the support portion position of the cleaning blade 61 and the center axis position O of the photosensitive drum 26 at a predetermined distance, the above-described penetration amount d and the set angle Θ are determined, and thereby the cleaning blade is set with a predetermined contact pressure. 61 can be brought into contact with the photosensitive drum 26. Such a support method of the cleaning blade 61 managed by the penetration amount d and the set angle Θ is very widely used because of its simple structure and low cost.

As a conventional example, for example, Patent Document 1 can be cited.
Japanese Patent Laid-Open No. 07-199761

  However, the conventional technique has the following problems. In recent years, an increasing number of models use spherical toner, which is spherical toner, for reasons such as improving developability and transferability and improving the quality of color images.

  As the spherical toner, for example, using a scanning electron microscope, 100 or more toner images magnified 1000 times are randomly extracted, the image information is analyzed through an interface, and calculated by the following formula. A substantially spherical toner having an average circularity of 0.920 or more is used. When the toner particles are a perfect sphere, the circularity is 1.

  When conventional pulverized toner is used, the fine powder contained in the toner accumulates at the edge of the cleaning blade, and the blocking layer made up of the retained fine powder prevents the toner from slipping through the blade. However, when the spherical toner as described above is used, the particle diameter of the toner is substantially uniform, and since there is almost no fine powder in the toner, the blocking layer is hardly formed. In addition, since the toner is also spherical, when the photosensitive member, intermediate transfer member, and residual toner reach the cleaning blade part, in the case of a normal urethane blade, the toner can easily pass through the blade, and there is a risk that many cleaning defects will occur. There was a problem that there was.

  When the above spherical toner is used, the contact pressure of the blade with the member to be cleaned may be increased in order to ensure the cleaning property. As described above, the blade contact pressure is normally controlled by the blade penetration amount d and the set angle Θ. However, if the penetration amount d is unnecessarily large, the blade does not contact the member to be cleaned but hit the belly. It will be in a state and a cleaning defect will be caused.

  Depending on the conditions, there was a failure (blade turning) in which the tip 61a of the cleaning blade 61 was reversed so as to follow the rotation direction of the photosensitive drum 26.

  Therefore, as a technique capable of solving such a problem, a method of attaching a backup member to a blade has already been proposed as disclosed in Japanese Patent Application Laid-Open No. 7-199761. However, in this method, the backup member also inhibits vibration in the traveling direction of the member to be cleaned of the blade. The cleaning mechanism in blade cleaning is a contact portion when the cleaning blade is in contact with the member to be cleaned. First, the blade edge portion that is in close contact with the surface of the member to be cleaned by the frictional force acting on the contact portion travels. Shear deformation and compression deformation in the direction of travel. Next, it is considered that the energy accumulated in the edge portion due to the stress acts as a rebound elastic force and returns to the original state by so-called stick-slip motion. Therefore, if the vibration of the blade is hindered, the toner scraping effect due to the vibration of the blade is also lowered.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and the object of the present invention is to arbitrarily set the contact pressure without depending on the set angle Θ or the penetration amount d. Another object of the present invention is to provide a cleaning device and an image forming apparatus that can be used and that do not hinder the vibration of the blade to be cleaned in the running direction.

  The above object is achieved by the image forming apparatus according to the present invention.

  According to a first aspect of the present invention, there is provided a cleaning apparatus comprising a cleaning member that travels and a counter-type cleaning blade made of an elastic material that abuts the cleaning member, in order to remove toner remaining on the surface of the cleaning member. In addition, the cleaning device includes a pressurizing unit that pressurizes a surface opposite to the cleaning edge of the cleaning blade in order to increase a contact pressure of the cleaning blade to the member to be cleaned. This is a cleaning device.

  According to a second aspect of the present invention, in the cleaning device according to the first aspect, the pressurizing means is a biasing member attached only to a tip portion of the free length of the cleaning blade. This is a cleaning device.

  A third aspect of the present invention is the cleaning apparatus according to the second aspect, wherein the biasing member pressurizes a tip including an edge of the cleaning blade.

  According to a fourth aspect of the present invention, in the cleaning device according to the second and third aspects, the biasing member is a spring that applies a restoring force in a direction in which the cleaning blade is brought into contact with the member to be cleaned. This is a cleaning device.

  According to a fifth aspect of the present invention, in the cleaning device according to the second and third aspects, the urging member provides a restoring force in a direction in which the cleaning blade is brought into contact with the member to be cleaned, rubber, or the like A cleaning device characterized by being an elastic body.

  According to a sixth aspect of the present invention, in the cleaning device according to any one of the first to fifth aspects, the member to be cleaned is at least one of a photosensitive drum, a transfer roller, an intermediate transfer body, and a cleaning roller. This is a cleaning device.

  A seventh aspect of the present invention is the cleaning apparatus according to the sixth aspect, wherein a surface of the member to be cleaned is covered with a resin layer.

  The invention according to claim 8 is the cleaning apparatus according to claim 6, wherein the surface of the member to be cleaned has a surface roughness Rz of 2 μm or less and a contact angle with respect to pure water of 90 degrees or more. This is a cleaning device.

  The invention according to claim 9 uses toner having an average circularity of 0.920 or more and an average particle diameter of 3 μm to 10 μm in a circularity distribution based on the number of circularities defined by the following formula. In the image forming apparatus including a cleaning device that forms an image and removes toner remaining on the member to be cleaned by a cleaning blade, the cleaning blade of the cleaning device increases the contact pressure to the member to be cleaned. In addition, the image forming apparatus further includes a pressing unit that pressurizes a surface opposite to the cleaning edge of the cleaning blade.

Circularity = (perimeter of a circle having the same projected area as the particle image) / (perimeter of the projected image of the particle image)
According to a tenth aspect of the present invention, in the image forming apparatus according to the ninth aspect, the pressurizing means is a biasing member attached to only the tip portion of the free length of the cleaning blade. An image forming apparatus characterized by the above.

  According to an eleventh aspect of the present invention, in the image forming apparatus according to the tenth aspect, the urging member pressurizes a tip including an edge of the cleaning blade.

  A twelfth aspect of the present invention is the image forming apparatus according to the tenth and eleventh aspects, wherein the urging member is a spring that applies a restoring force in a direction in which the cleaning blade is brought into contact with the member to be cleaned. An image forming apparatus characterized by the above.

  According to a thirteenth aspect of the present invention, in the image forming apparatus according to the tenth and eleventh aspects, the urging member provides a restoring force in a direction in which the cleaning blade is brought into contact with the member to be cleaned, and rubber. An image forming apparatus characterized by being an elastic body.

  According to a fourteenth aspect of the present invention, in the image forming apparatus according to any one of the ninth to thirteenth aspects, the member to be cleaned is at least one of a photosensitive drum, a transfer roller, an intermediate transfer member, and a cleaning roller. An image forming apparatus.

  According to a fifteenth aspect of the present invention, in the image forming apparatus according to the fourteenth aspect, the surface of the member to be cleaned is covered with a resin layer.

  According to a sixteenth aspect of the present invention, in the image forming apparatus according to the fourteenth aspect, the surface of the member to be cleaned has a surface roughness Rz of 2 μm or less and a contact angle with respect to pure water of 90 degrees or more. An image forming apparatus.

  According to a seventeenth aspect of the present invention, in the image forming apparatus according to the fourteenth aspect, a first image that forms an image having margins at all of the front end portion, rear end portion, left end portion, and right end portion of the transfer material. And a second image forming mode for forming an image having no margin in at least one of the leading edge, the trailing edge, the left edge, and the right edge of the transfer material. The image forming apparatus.

  As described above, according to the present invention, even when spherical toner is used for image formation, the contact pressure can be arbitrarily determined without depending on the set angle Θ and the penetration amount d, and the secondary of the blade can be determined. Since the vibration in the running direction of the transfer roller is not hindered, it is possible to obtain a good cleaning effect without causing a cleaning failure such as hitting or turning the blade.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, what attached | subjected the same code | symbol in each drawing has the same structure or effect | action, The duplication description about these was abbreviate | omitted suitably.

<First Embodiment>
In this embodiment, in the image forming apparatus capable of forming a marginless image that requires cleaning of the secondary transfer roller, the secondary transfer roller is attached by attaching a biasing member only to the tip of the cleaning blade. It can be reliably cleaned.

[Schematic configuration of image forming apparatus]
FIG. 1 is a diagram showing a schematic configuration of a four-drum full-color image forming apparatus using an intermediate transfer belt, which is an example of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus according to the present invention may be an electrophotographic laser printer, an electrophotographic copying machine, a facsimile, or an electrostatic recording printer, copying machine, facsimile, etc. There may be.

  In FIG. 1, 1 is a four-drum full-color image forming apparatus (hereinafter referred to as “apparatus main body”), P (PY, PM, PC, PBk) is detachably provided in the apparatus main body 2 and is yellow (Y), magenta (M), cyan (C) and black (Bk) process cartridges of four colors, 31 is an intermediate transfer body unit having an intermediate transfer belt 30 as an intermediate transfer body, and 25 is a fixing device.

  Here, the process cartridge P is disposed on the outer peripheral surface of the photosensitive drum 26 (26Y, 26M, 26C, 26Bk), which is an image carrier, and the photosensitive drum 26, respectively. The electrostatic latent images of the respective colors on the surface of the photosensitive drum formed by exposure by the primary charger 50 and the laser exposure device 28 (28Y, 28M, 28C, 28Bk) are converted into yellow, magenta, A developing unit 51 that develops using cyan and black toners is provided, and is arranged in parallel along the intermediate transfer belt 30. For example, the photosensitive drum 26 is configured by applying an organic photosensitive semiconductor layer (OPC photosensitive layer) to the outer peripheral surface of an aluminum cylinder having a diameter of 30 mm. The intermediate transfer belt 11 is formed of PI (polyimide resin) in the present embodiment. In this embodiment, a contact type two-component development system is employed, but the scope of application of the present invention can also be applied to an apparatus using another development system.

  Further, a primary transfer roller 52 that forms a primary transfer portion together with the photosensitive drum 26 is disposed opposite to the position where the intermediate transfer belt 30 is sandwiched with the photosensitive drum 26.

  On the other hand, the intermediate transfer belt unit 31 includes an intermediate transfer belt 30 and three rollers: a driving roller 100 that stretches the intermediate transfer belt 30, a tension roller 105, and a secondary transfer counter roller 108. Further, in order to clean the intermediate transfer belt 30, an intermediate transfer belt cleaning device 32 is disposed at a position facing the tension roller 105 and the intermediate transfer belt 30.

  Reference numeral 27 denotes a secondary transfer roller disposed at a position sandwiching the intermediate transfer belt 30 of the secondary transfer counter roller 108. Further, a secondary transfer roller cleaning device 33 is disposed at a position where it abuts on the secondary transfer roller 27.

  Reference numeral 3 denotes a feeding unit that feeds the transfer material S to the secondary transfer unit configured by a contact portion between the secondary transfer roller 27 and the secondary transfer counter roller 108 with the intermediate transfer belt 30 interposed therebetween. The feeding unit 3 includes a cassette 20 that stores a plurality of transfer materials S, a feeding roller 21, a double feed preventing retard roller pair 22, a transport roller 23, a registration roller pair 24, and the like.

  The intermediate transfer belt unit 31 is detachably provided on the apparatus main body 2. When the intermediate transfer belt unit 31 is taken out, the unit replacement door 500 attached to the side wall surface of the apparatus main body 2 is opened and then pulled out of the apparatus main body. ing. Further, the unit replacement door 500 is used not only for opening and closing the intermediate transfer belt unit but also for removing jammed paper outside the apparatus.

  The toner used in the developing device 51 is a sphere having an average value of circularity defined by the following formula of 0.920 or more, for example, a circularity of about 0.94 and an average particle diameter of 3 μm to 10 μm. Toner is used.

Circularity = (perimeter of a circle having the same projected area as the particle image) / (perimeter of the projected image of the particle image)
[Image forming operation]
Next, an image forming operation of the four-drum full-color image forming apparatus 1 configured as described above will be described.

  When the image forming operation is started, first, the transfer material S in the cassette 20 is fed by the feed roller 21 and then separated one by one by the retard roller pair 22 and then passed through the transport roller 23 and the like. It is conveyed to the roller pair 24. At this time, the registration roller pair 24 stops rotating, and the transfer material S is abutted against the nip of the registration roller pair 24, whereby the skew of the transfer material S is corrected.

  On the other hand, in parallel with the transfer operation of the transfer material S, for example, in the yellow process cartridge PY, the surface of the photosensitive drum 26Y is first uniformly negatively charged by the primary charger 50, and then the image is output by the laser exposure device 28Y. By performing the exposure, an electrostatic latent image corresponding to the yellow image component of the original is formed on the surface of the photosensitive drum 26Y.

  Next, the electrostatic latent image is developed with a negatively charged yellow toner by the developing device 51 and visualized as a yellow toner image. The yellow toner image thus obtained is primarily transferred onto the intermediate transfer belt 30 by the primary transfer roller 52. After the toner image is transferred, the transfer residual toner adhering to the surface of the photosensitive drum 26Y is removed by the cleaner 53 and used for the next image formation.

  Then, such a toner image forming operation is performed at a predetermined timing in the other process cartridges P, and each color toner image formed on each photosensitive drum 26 is transferred onto the intermediate transfer belt 30 by each primary transfer unit. Are transferred to the primary transfer.

  Next, the four-color toner images transferred onto the intermediate transfer belt 30 in this manner are moved to the secondary transfer portion as the intermediate transfer belt 30 rotates clockwise in the drawing. Further, the transfer material S whose skew has been corrected by the registration roller pair 24 is sent to the secondary transfer portion in time with the image on the intermediate transfer belt 30.

  Thereafter, the four-color toner images on the intermediate transfer belt 30 are secondarily transferred onto the transfer material S by the secondary transfer roller 27 in contact with the intermediate transfer belt 30 with the transfer material S interposed therebetween. Then, the transfer material S onto which the toner image has been transferred in this way passes through the post-transfer conveyance unit 34 and is conveyed to the fixing device 25 to fix the toner image, and then the lower discharge roller pair 29a and the upper discharge roller pair. By 29b, it is discharged and stacked on the upper surface of the apparatus main body. The intermediate transfer belt 30 that has finished the secondary transfer has the transfer residual toner remaining on the surface removed by the intermediate transfer belt cleaning device 32, and the toner adhering to the secondary transfer roller 27 is subjected to the secondary transfer roller cleaning. It is cleaned by the device 33.

[No-margin image formation mode]
In the image forming apparatus of this embodiment, as an image forming mode, there is a margin mode in which a margin portion is provided on the end portion of the transfer material S as usual and an image is printed, and an image without a margin portion is provided on the transfer material S. Has no margin mode for printing.

  FIG. 2 is a schematic diagram showing the relationship between the size of the printing area M and the transfer material S of the image forming apparatus. In the margin mode, as shown in FIG. 2A, the printing area M is set to be smaller than the size of the transfer material S so that the margin portions are secured at the ends of the four sides on the transfer material S. Yes. The size of the margin is set as appropriate. In this embodiment, a margin area of 3 mm at least on the transfer material S is ensured by setting the print area M in the margin mode inward by 3 mm from the end portions of the four sides of the transfer material S.

  On the other hand, in the no margin mode, as shown in FIG. 2 (b), there is no margin at the end of the four sides of the transfer material S by setting the printing area M larger than the size of the transfer material S. Images can be printed. That is, by allowing the toner image to protrude from the transfer material, the toner image can be placed up to the end of the transfer material S even if the position of the transfer material S is slightly shifted. In this embodiment, the printing area M in the marginless mode is set to be 2 mm outside from the end portions of the four sides of the transfer material S.

  Accordingly, in the no margin mode, when the toner image is transferred from the photosensitive drum 26 to the intermediate transfer belt 30 and transferred from the intermediate transfer belt 30 to the transfer material S, the toner image positioned outside the transfer material S is secondary. It is directly transferred onto the transfer roller 27. The toner directly transferred to the secondary transfer roller must be removed by the secondary transfer roller cleaning device. However, compared to the normal printing mode (margin mode), a large amount of toner is pushed to the cleaning section. Will come. Further, since the toner to be removed is partially biased, the toner and the external additive act as a lubricant only in that portion, and the friction coefficient between the blade and the secondary transfer roller varies in the longitudinal direction of the blade. Since both ends of the transfer material have to clean a large amount of toner, it is desired to increase the pressing force of the blade. However, since the friction coefficient of the central portion of the blade is large, it is easy to turn from the central portion of the blade. In such a situation where the setting of the cleaning becomes more severe, the present invention is more effective.

  Note that the print area M for the transfer material S in the marginless mode is not limited to the set value of the present embodiment, and may be any size as long as an image without a margin can be completely formed on the transfer material S. Further, in the present embodiment, all four sides have no margin, but the present invention is not limited to all four sides.

[Secondary transfer roller cleaning device]
In the present embodiment, the cleaning blade of the secondary transfer roller cleaning device 33 is configured as shown in FIG.

  A cleaning blade 70 is provided, and the cleaning blade 70 is supported by a cleaning blade support member 71. The edge 70a at the tip of the cleaning blade 70 comes into pressure contact with the surface of the secondary transfer roller 27 and scrapes off and removes the residual toner T generated at the transfer site and arriving at the cleaning device 33.

  The cleaning blade 70 is made of urethane resin. For example, the free length A is set to 10 mm and the thickness is set to 2 mm. In this embodiment, a blade having a JIS-A hardness of 77 and a rebound resilience of 30 at room temperature of 25 ° C. is used. The setting angle Θ of the cleaning blade 70 with respect to the secondary transfer roller 27 is 35 degrees, and the penetration amount d is set to 1 mm.

  In order to increase the contact pressure of the cleaning blade 70 to the secondary transfer roller, a coil spring 72 is disposed as an urging member that pressurizes the surface of the cleaning blade 70 opposite to the cleaning edge 70a. In this embodiment, the coil spring 72 is used as the urging member, but the type of spring may be another type of spring such as a leaf spring. The upper part of the coil spring 72 is supported by a support member 74. FIG. 4 is a bird's-eye view of FIG. 3. As shown in FIG. 4, 13 coil springs 72 are arranged at equal intervals in the longitudinal direction of the blade, and the blade 70 is uniformly applied between the coil spring 72 and the blade 70. For pressure, metal spacers 73 having a thickness of about 0.2 mm are uniformly arranged in the longitudinal direction. The number of the coil springs 72 and the thickness of the spacer 73 may be appropriately selected as long as the blade can be uniformly pressed. In addition, the coil spring 72 and the support member 74, the coil spring 72 and the spacer 73, and the spacer 73 and the blade 70 are fixed with an adhesive so that the vibration of the blade 70 does not shift the direction perpendicular to the pressurizing direction. However, this method may be selected as appropriate.

  If the area to which the urging member pressurizes becomes an area of ½ or more of the free length A from the tip of the blade 70, the blade may be in a state of being abdomen. Although it is desirable to pressurize a region of 1/2 or less of the free length A from the tip of 70, it is more desirable to pressurize a region of 1/4 or less of the free length A from the tip of the blade 70. Further, in order to maximize the effect of the present invention, the edge of the blade 70 can be increased in that the pressing force to the blade edge portion 70a in contact with the secondary transfer roller 27 can be increased without causing the blade to bend. It is most desirable to pressurize the containing tip. In this embodiment, the width of the spacer 73 is 2 mm, and the tip including the edge of the blade 70 is pressurized.

  The secondary transfer roller 27 has, for example, an outer shape of 23 mm and an electric resistance value of about 107Ω. As shown in FIG. 5, this transfer roller is provided with a semiconductive elastic layer 27b made of foamed urethane rubber or the like on a metal shaft 27a. On this elastic layer, the 10-point average roughness Rz is 2 μm or less. A resin layer 27c having a contact angle with respect to pure water of 90 degrees or more is provided. If the surface roughness Rz exceeds 2 μm, it is not preferable because the spherical toner is likely to be caught in the concave portion on the surface of the secondary transfer roller 27 and easily passes through the cleaning blade. The contact angle is a value determined by the surface tension of the material and the shape of the surface, but if the pure water contact angle is 90 degrees or more, it is difficult for toner and external additives to adhere. It is preferable in that it becomes easy. If the hardness of the transfer roller is too low, the blade will bite into the roller surface at the contact portion of the blade and the blade will be easily turned over, so the Asker C hardness is 40 degrees or more, and the surface hardness made by Kobunshi Keiki Co., Ltd. It is desirable that the value measured using a cylindrical indenter having a height of 0.5 mm and a diameter of 0.16 mm with a total MD-1 is 50 degrees or more. In this example, a PFA tube is used as the resin layer, each having a 10-point average roughness Rz of 1.7 μm, a contact angle with pure water of 108 degrees, a degree ASKER-C hardness of 48 degrees, and a micro hardness of 64 degrees. is there.

  When the abutment member is not used and the blade is brought into contact with the transfer roller only, the linear pressure is 15 g / cm. In this state, a cleaning failure occurs due to toner slipping. When the linear pressure was increased by increasing the intrusion amount d from there, the blade was in contact with the belly, and cleaning failure occurred again. Also, when the linear pressure was increased by increasing the set angle Θ, the blade turned up. Therefore, when the pressing force was increased by the urging member, a good cleaning result could be obtained when the linear pressure was 30 g / cm or more. If an excessively large pressing force is applied to the blade, wear of the blade edge and the secondary transfer roller may be promoted. In this embodiment, the linear pressure was set to 35 g / cm.

  In the above configuration, in the case of the cleaning device according to this embodiment, even when spherical toner is used, the contact pressure can be arbitrarily determined without depending on the set angle Θ and the penetration amount d, and Since the vibration of the blade in the running direction of the secondary transfer roller is not hindered, a good cleaning effect can be obtained. Therefore, it is possible to obtain a good image in which toner does not adhere to the back surface of the transfer material even when an image without margins is printed or when a jam process is performed.

<Second Embodiment>
A second embodiment will be described. The schematic configuration of the image forming apparatus, the image forming operation, the marginless image forming mode, and the above-described first embodiment are the same as those in the first embodiment, and a description thereof will be omitted.

[Secondary transfer roller cleaning device]
FIG. 6A shows the configuration of the cleaning device 33 for the secondary transfer roller 27 in the second embodiment. In the second embodiment, a resin 75 is used as an urging member that pressurizes the cleaning blade 70. Further, the pressing force by the urging member can be changed according to the situation where cleaning is necessary or unnecessary, for example, when printing an image with no margin or after performing jam processing. Therefore, the resin 75 is supported by a pressing force variable mechanism 200 that can control the cleaning blade pressing force by a signal from a controller (not shown) of the image forming apparatus main body.

  Here, the variable pressing force mechanism 200 has an electromagnetic solenoid 76 attached to a fixed frame (not shown). The electromagnetic solenoid 76 can move the operating rod 77 in the vertical direction, and can move the resin 75 in the vertical direction via the biasing member support member 74. Therefore, the pressing force of the cleaning blade 70 can be freely determined by the operation of the electromagnetic solenoid 76. Further, the blade 70 can be separated from the secondary transfer roller 27 as shown in FIG. In this embodiment, in a normal state, the linear pressure of the blade 70 is set to 15 g / cm, and when printing an image without a margin, a large amount of toner is not cleaned while the secondary transfer roller makes a round. Therefore, the linear pressure is set to 35 g / cm. Further, when there is no use for a long time, there is a concern about the setting property of the transfer roller (a phenomenon in which the roller surface is not restored while being deformed), and therefore, it is in a separated state as shown in FIG.

  The material of the blade 70 is a urethane resin as in the first embodiment, and a blade having a JIS-A hardness of 77 degrees at a room temperature of 25 ° C. and a rebound resilience of 30% is used. The setting angle Θ of the cleaning blade 70 with respect to the secondary transfer roller 27 is set to 35 degrees, the penetration amount d is set to 1 mm, the free length A is set to 10 mm, and the thickness is set to 2 mm.

  In this embodiment, as the resin 75 of the urging member, the same urethane resin as that of the blade and having a thickness of 2 mm in the horizontal direction in FIG. 6A and a length of 7 mm in the vertical direction in FIG. 6A is used. However, other types of resin may be used, and the thickness and length of the resin 75 of the biasing member may be set as appropriate. Further, the blade 70 and the resin 75 of the biasing member 75 may be integrally molded. In this embodiment, the resin 75 and the blade 70 are bonded by an adhesive.

  Although the two types of secondary transfer roller cleaning devices have been described above, this is not limited to the transfer roller. For example, the cleaning device uses a cleaning blade such as a photosensitive drum, an intermediate transfer belt, or a cleaning roller. Can do.

1 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus according to a first embodiment. FIG. 4 is a schematic diagram illustrating a relationship between a printing area and a transfer material size. It is a longitudinal cross-sectional view which shows schematic structure of the secondary transfer roller cleaning apparatus of 1st Embodiment. FIG. 4 is an overhead view of FIG. 3 showing the arrangement of the blade urging member and the spacer. It is a figure which shows a secondary transfer roller. It is a longitudinal cross-sectional view which shows schematic structure of the secondary transfer roller cleaning apparatus of 2nd Embodiment. It is a longitudinal cross-sectional view which shows schematic structure of the image forming apparatus using the conventional cleaning apparatus. It is an enlarged view of a process cartridge using a conventional cleaning device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus main body 21 Feed roller 22 Retard roller pair 23 Conveying roller 24 Registration roller pair 25 Fixing device 26 Photoconductor drum 27 Secondary transfer roller 27a Secondary transfer roller core metal 27b Secondary transfer roller elastic layer 27c Secondary transfer Resin layer on roller surface 28, 28Y, 28M, 28C, 28Bk Exposure device 29, 29a, 29b Paper discharge roller pair 30 Intermediate transfer belt 31 Intermediate transfer belt unit 32 Intermediate transfer belt cleaning device 33 Secondary transfer roller cleaning device 50 Charging device 51 Developing Device 52, 52Y, 52M, 52C, 52Bk Primary Transfer Roller 53 Photoconductor Cleaning Device 61 Photoconductor Cleaning Blade 61a Photoconductor Cleaning Blade Edge 62 Rake Sheet 63 Waste Toner Transport Screw 64 Screw 65 Blur Support unit 66 housing 66a toner storage unit 70 secondary transfer roller cleaning blade 71 blade support unit 72 coil spring 73 spacer 74 support member 75 resin for pressing the blade 76 electromagnetic solenoid 77 actuating rod 200 pressing force variable mechanism A blade Free length d Blade penetration amount Θ Setting angle M Print area O Center of secondary transfer roller P, PY, PM, PC, PBk Process cartridge S Transfer material T Toner

Claims (17)

  In a cleaning device including a cleaning member that travels and a counter-type cleaning blade made of an elastic material that contacts the cleaning member, in order to remove toner remaining on the surface of the cleaning member, the cleaning device includes the cleaning member A cleaning apparatus comprising pressurizing means for pressurizing a surface opposite to a cleaning edge of the cleaning blade in order to increase a contact pressure of the blade to the member to be cleaned.   2. The cleaning apparatus according to claim 1, wherein the pressurizing means is a biasing member attached only to a tip portion of the free length of the cleaning blade.   The cleaning device according to claim 2, wherein the biasing member pressurizes a tip including an edge of the cleaning blade.   4. The cleaning apparatus according to claim 2, wherein the urging member is a spring that applies a restoring force in a direction in which the cleaning blade is brought into contact with the member to be cleaned.   4. The cleaning device according to claim 2, wherein the urging member is an elastic body such as resin and rubber that provides a restoring force in a direction in which the cleaning blade is brought into contact with the member to be cleaned. Cleaning device to do.   6. The cleaning device according to claim 1, wherein the member to be cleaned is at least one of a photosensitive drum, a transfer roller, an intermediate transfer member, and a cleaning roller. .   The cleaning apparatus according to claim 6, wherein a surface of the member to be cleaned is covered with a resin layer.   The cleaning apparatus according to claim 6, wherein the surface of the member to be cleaned has a surface roughness Rz of 2 μm or less and a contact angle with respect to pure water of 90 degrees or more. In the circularity distribution based on the number of circularities defined by the following formula, an image is formed using toner having an average circularity of 0.920 or more and an average particle diameter of 3 μm to 10 μm, and a member to be cleaned In the image forming apparatus including a cleaning device that removes the toner remaining on the cleaning blade with a cleaning blade, the cleaning blade of the cleaning device includes a cleaning edge of the cleaning blade to increase a contact pressure against the member to be cleaned. Has an pressing means for pressing the surface on the opposite side.
Circularity = (perimeter of a circle having the same projected area as the particle image) / (perimeter of the projected image of the particle image)   10. The image forming apparatus according to claim 9, wherein the pressurizing unit is an urging member attached only to a tip portion of ½ of the free length of the cleaning blade.   The image forming apparatus according to claim 10, wherein the urging member pressurizes a tip portion including an edge of the cleaning blade.   12. The image forming apparatus according to claim 10, wherein the urging member is a spring that applies a restoring force in a direction in which the cleaning blade is brought into contact with the member to be cleaned.   12. The image forming apparatus according to claim 10, wherein the urging member is an elastic body such as a resin and rubber that provides a restoring force in a direction in which the cleaning blade is brought into contact with the member to be cleaned. An image forming apparatus.   14. The image forming apparatus according to claim 9, wherein the member to be cleaned is at least one of a photosensitive drum, a transfer roller, an intermediate transfer member, and a cleaning roller. Forming equipment.   15. The image forming apparatus according to claim 14, wherein a surface of the member to be cleaned is covered with a resin layer.   The image forming apparatus according to claim 14, wherein the surface of the member to be cleaned has a surface roughness Rz of 2 μm or less and a contact angle with respect to pure water of 90 degrees or more.   15. The image forming apparatus according to claim 14, wherein a first image forming mode for forming an image having a blank portion at all of a front end portion, a rear end portion, a left end portion, and a right end portion of the transfer material, and a front end portion of the transfer material An image forming apparatus comprising: a second image forming mode for forming an image having no margin at at least one of the rear end, the left end, and the right end.

Images