JP4936539B2 - Image forming apparatus - Google Patents

Description

  The present invention includes a rotatable image carrier, a toner image forming unit that forms a toner image on the image carrier, a transfer unit that transfers the toner image to a recording medium, and a transfer residue from the surface of the image carrier. The present invention relates to a transfer type image forming apparatus having cleaning means for removing toner.

  In the above, examples of the rotatable image bearing member include a rotating drum type or rotating belt type electrophotographic photosensitive member in an electrophotographic image forming apparatus. In addition, there is a rotating drum type or rotating belt type electrostatic recording dielectric in the electrostatic recording apparatus. Further, a magnetic recording magnetic body of a rotating drum type or a rotating belt type in a magnetic recording apparatus can be mentioned. The recording medium is a recording material such as transfer paper, an OHP sheet, or a label, or an intermediate transfer member of a rotating drum type or a rotating belt type.

  2. Description of the Related Art Conventionally, in a transfer type image forming apparatus, a blade cleaning method is often employed as a cleaning unit that removes transfer residual toner from an image carrier after a toner image is transferred to a recording medium because of its good cleaning property.

  In the blade cleaning method, the edge portion of an elastic blade (cleaning blade) made of polyurethane or the like is disposed in contact with the image carrier, and the transfer residue on the image carrier due to the friction caused by the rotation of the image carrier. The image carrier surface is cleaned by scraping off the toner. The cleaned image carrier is prepared for the next image forming step.

  The physical properties of the cleaning blade and the manner of contact with the image carrier greatly depend on the ease of cleaning and the surface property of the image carrier depending on the degree of adhesion of the transfer residual toner to the image carrier. Also, the cleaning properties are greatly affected by the physical properties such as toner shape, particle size, and material. Therefore, it is necessary to select a blade suitable for that and set it to an appropriate angle and contact load with respect to the image carrier. In the actual selection and setting of the cleaning blade, the present condition is that the optimum condition is found through repeated trial and error.

  On the other hand, the cleaning performance and the surface layer wear condition of the image carrier differ depending on the actual operating environment, particularly temperature and humidity fluctuations, and therefore it is difficult to perform cleaning with only the cleaning blade throughout the durability life. For this reason, some cleaning auxiliary members are provided with a cleaning brush that rotates while contacting the image carrier. Usually, this cleaning brush is disposed upstream of the image carrier contact portion of the cleaning blade in the image carrier rotation direction, scrapes off transfer residual toner on the image carrier after transfer, and cleans the cleaning blade. It also has the purpose of facilitating. For this reason, in some cases, the cleaning brush is grounded or a bias is applied in order to weaken the adhesion force of the transfer residual toner to the image carrier (Patent Document 1).

  In recent years, various types of image forming apparatuses for obtaining a color image using toners of four colors of yellow, magenta, cyan, and black have been proposed. Some use toner. When such toner is used, it is effective to provide a cleaning brush that is a cleaning auxiliary member as described above, since it is easy to slip through the cleaning blade if the transfer residual toner adheres firmly to the image carrier. It is.

Furthermore, there is also an apparatus having a mechanism in which a solid lubricant such as zinc stearate is brought into contact with the cleaning brush and the lubricant is applied to the surface of the image carrier via the cleaning brush (Patent Document 2). When a lubricant such as zinc stearate is applied to the surface of the image carrier, a thin film of lubricant formed on the image carrier improves the cleaning performance with a cleaning blade, and filming with an external toner additive It is known to prevent. It is also known that this lubricant film is effective in preventing image blur.
Japanese Patent Laid-Open No. 04-124690 Japanese Patent Laid-Open No. 09-090839

  However, in a configuration in which such a lubricant is supplied to the surface of the image carrier with a cleaning brush, the lubricant may not be applied properly. For example, when the rotational peripheral speed of the image carrier is high or when the supply of lubricant is excessive, the solid lubricant is sent to the contact nip portion between the cleaning blade and the image carrier in the powder state, and the cleaning blade May cause local damage. As a result, toner leakage due to a cleaning defect may occur, resulting in an image defect on the recording medium.

  In addition, after a long period of use, if the cleaning brush is scraped or the solid lubricant is partially scraped, the lubricant cannot be uniformly applied to the surface of the image carrier, resulting in partial filming and image flow. There was a case.

  The present invention solves the above problems. An object of the present invention is to provide an image forming apparatus that can reliably apply a solid lubricant to the surface of an image carrier and can obtain a high-quality image that does not cause poor cleaning or image flow through durability.

In order to achieve the above object, a typical configuration of an image forming apparatus according to the present invention includes a rotatable image carrier, toner image forming means for forming a toner image on the image carrier, and the toner image. In the image forming apparatus having a transfer unit that transfers to a recording medium and a cleaning unit that removes transfer residual toner from the surface of the image carrier, the cleaning unit forms a nip portion with the image carrier and transfers the transfer A cleaning blade that scrapes the remaining toner, a rotating member that rotates in contact with the image carrier on the upstream side of the nip portion in the rotation direction of the image carrier, and a solid on the surface of the image carrier via the rotating member A lubricant application mechanism that applies a lubricant, and the rotary member and the nip portion have a particle shape of a cubic shape and / or a rectangular parallelepiped shape, and a primary particle size of 30 to 300. m inorganic fine powder is supplied in the in the rotating member, characterized in that said inorganic fine powder is relatively maintained easily region and holding hard region are provided alternately in the circumferential direction.

  According to the present invention, the solid lubricant is stably applied to the image carrier even when the process speed of the image forming apparatus is increased or after long-term durability, and image defects such as image flow and filming are performed. Can be prevented.

  Next, an embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings.

[Example 1]
(1) Description of Overall Configuration of Example Image Forming Apparatus FIG. 1 is a schematic diagram showing a schematic configuration of an image forming apparatus in the present embodiment. This image forming apparatus is a transfer type electrophotographic image forming apparatus, and is a multi-function machine having a copying machine function, a printer function, and a facsimile facsimile function machine.

  A is an image forming unit, and B is a document reading unit (document reading unit) disposed on the top of the image forming unit A. In the document reading section B, 21 is a document table glass, and 22 is a document pressing plate that can be opened and closed with respect to the upper surface of the document table glass 21. The document O is placed on the document table glass 21 with the image surface facing downward according to a predetermined placement standard, and the document pressing plate 22 is placed thereon to set the document O. The document pressing plate 22 may be an automatic document feeder (ADF / RDF) to automatically feed a sheet-shaped document onto the document table glass 21. Reference numeral 23 denotes an original reading unit that is driven to move along the lower surface of the original table glass 21. The document reading unit 23 scans the downward image surface of the set document O on the document table glass 21. As a result, the original image is photoelectrically read as electrical image information and input to the image processing unit of the controller unit (control circuit unit) C.

  In the image forming unit A, reference numeral 1 denotes a drum-type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) as a rotatable image carrier. The photosensitive drum 1 is rotationally driven by a driving mechanism (not shown) at a predetermined speed (process speed) in the clockwise direction of an arrow, in this embodiment, 200 mm / sec. The photosensitive drum 1 is formed by applying a layer of photosensitive material such as OPC to the outer peripheral surface of a cylindrical substrate such as aluminum. In this embodiment, a highly durable photosensitive drum having a surface layer cured by electron beam irradiation was used. As will be described later, in the present invention, since the function of the cleaning device for the photosensitive drum 1 can be maintained for a long period of time, it is preferable that the photosensitive body be excellent in wear and used for a long period of time. The photoconductor is not limited to that of the present embodiment, and a normal organic photoconductor, an inorganic photoconductor such as a-Si, and the like are also preferably used. By using the configuration of the present invention, even when a highly durable photosensitive drum having a low wear rate is used, stable cleaning can be performed over a long period of time.

The photosensitive drum 1 that is driven to rotate is subjected to overall exposure by a pre-exposure lamp (eraser lamp) 7 serving as a charge eliminating unit. As a result, the surface of the photosensitive drum 1 is uniformly discharged, and the electrical memory in the previous image forming process is erased. The charge eliminating surface of the photosensitive drum 1 is uniformly charged to a predetermined polarity / potential by a charging means (charging device, charging device) 2. In this embodiment, the charging means 2 is a contact charging means using a charging roller (roller-type charging member, roller charger). The charging roller 2 is arranged in contact with the surface of the photosensitive drum 1 (image carrier surface). In this embodiment, the charging roller 2 includes a cylindrical or columnar conductive member (core metal) such as iron or stainless steel, and a volume specific resistance of 10 ⁴ to 10 formed in a roller shape around the conductive member. It is composed of a 10 ¹² Ω · cm resistance layer. Further, a surface layer having a volume resistivity of 10 ⁴ to 10 ¹² Ω · cm may be provided so as to cover the surface of the resistance layer. The charging roller 2 is arranged substantially parallel to the generatrix direction of the photosensitive drum 1, and is driven to rotate as the photosensitive drum 1 rotates by being brought into contact with the photosensitive drum 1. By applying a predetermined charging bias to the conductive member of the charging roller 2 from the charging bias application power source S1, the surface of the rotating photosensitive drum 1 is uniformly charged to a predetermined polarity and potential. In this embodiment, a bias in which a predetermined direct current is superimposed on a predetermined alternating current is applied to the conductive member from the power supply unit S1 (AC method), and the surface of the photosensitive drum 1 is set to about −600 V as the dark portion potential VD. Uniform contact charging. As the charging bias, only a predetermined direct current may be applied (DC method).

  The contact charging member is not limited to the roller type as described above, but may be a blade type, a fur brush type, or a magnetic brush type. The charging unit 2 is not limited to the contact charging unit, and may be a proximity charging unit in which a charging member is disposed in proximity to the surface of the photosensitive drum 1 or a non-contact charging unit using a corona discharger. Even if the charging member of the contact charging means is not necessarily in contact with the surface of the object to be charged, it is close to non-contact if the dischargeable region determined by the voltage between the gap and the Paschen curve is reliably ensured between the charging member and the surface of the object to be charged. Even in the arranged configuration, the charged object can be charged. Proximity charging is this, and the charging member 2 is arranged to face the surface of the photosensitive drum 1 in a non-contact manner with a small gap of about several tens to several hundreds of micrometers. Then, a bias in which predetermined direct current is superimposed on predetermined alternating current is applied to the charging member (AC method), or only predetermined direct current is applied (DC method), so that the surface of the photosensitive drum 1 has a predetermined polarity and It is charged uniformly to the potential.

  Reference numeral 3 denotes image exposure means (exposure means for forming a latent image). In this embodiment, a laser scanner (laser scanning exposure apparatus) including a laser oscillator, a polygon mirror that rotates at high speed, an F-θ lens, a deflection mirror, and the like. ). In the copying machine mode, the image processing unit of the controller unit C inputs the electrical image information of the document image input from the document reading unit B to the laser scanner 3. The laser scanner 3 outputs laser light L that is ON / OFF controlled corresponding to the input image information, and scans and exposes the surface of the photosensitive drum 1 uniformly charged by the charging unit 2. As a result, a latent image corresponding to the image information of the document O is formed on the surface of the photosensitive drum 1. In the present embodiment, an electrostatic latent image of −200 V is formed on the surface of the photosensitive drum 1 as the bright portion potential VL.

  In the printer mode, electrical image information input to the controller unit C from an external device (not shown) such as a computer, an image scanner, or a workstation is processed by the image processing unit. Then, an image is input to the laser scanner 3 and the image forming unit A functions as a printer. In the facsimile reception mode, the electrical image information input from the counterpart facsimile machine (not shown) to the controller unit C is processed by the image processing unit. Then, the image is input to the laser scanner 3 and the image forming unit A functions as a facsimile receiver. In the facsimile transmission mode, electrical image information of the original image photoelectrically read by the original reading unit B is transmitted to the counterpart facsimile machine by the controller unit C.

  The electrostatic latent image formed on the surface of the photosensitive drum 1 is developed as a toner image (developer image) by a developing device (developing means, developing device) 4. In many cases, image exposure and reversal development are used in combination.

  In the above description, the charging unit 2, the image exposing unit 3, and the developing unit 4 are toner image forming units that form a toner image on the photosensitive drum 1.

  In this embodiment, the developing device 4 uses a magnetic one-component developing method as a developing method. Reference numeral 41 denotes a non-magnetic developing sleeve, which includes a fixed magnet roller 42. The developing sleeve 41 is coated with a negative toner having a particle diameter (average particle diameter) of 7 μm, and the developing sleeve 41 is rotated at the same speed as the photosensitive drum 1 with the distance from the surface of the photosensitive drum 1 fixed to 200 μm. A predetermined developing bias voltage is applied to 41 from the developing bias power supply unit S2. In this embodiment, the developing bias is a superposition of a DC voltage of −500 V and a rectangular AC voltage having a frequency of 1.8 MHz and a peak-to-peak voltage of 1.6 kV, and is used between the developing sleeve 41 and the photosensitive drum 1. Perform jumping development.

  The external additive formulation of the developer used in the present example is 1.0 part by weight of strontium titanate (indefinite shape, average particle size of about 1.0 μm) as an inorganic fine powder with respect to 100 parts by weight of toner, hydrophobicity Silica (indefinite shape, average particle size of about 20 nm) was externally added by 1.0 part by weight.

  In this embodiment, inorganic fine powder having a particle size (average particle size) of 30 to 300 nm as a primary particle having a cubic shape (substantially cubic shape) and / or a rectangular parallelepiped shape (substantially rectangular shape) is removed from the toner. In addition, it is configured to be supplied to the surface of the photosensitive drum 1.

  Inorganic fine powder has high hardness and excellent polishing performance. As the inorganic fine powder, for example, strontium titanate, barium titanate, calcium titanate and the like are used. By making the inorganic fine powder into a perovskite crystal form having a cubic shape and / or a rectangular parallelepiped shape, a particularly excellent polishing action is exhibited. This is because the particle shape is cubic and / or cuboid, the contact area with the object can be increased, and the cubic or cuboid ridge line abuts the object, This is considered to be because good scraping properties can be obtained.

  Inorganic fine powders such as strontium titanate in a perovskite crystal preferably have an average primary particle size of 30 nm to 300 nm. If the average particle size is less than 30 nm, the polishing effect of the particles is insufficient. On the other hand, if the average particle size exceeds 300 nm, the polishing effect is too strong. The polishing performance is greatly related to the particle size of the inorganic fine powder, and the larger the particle size, the greater the polishing effect.

  Examples of means for supplying the inorganic fine powder to the surface of the photosensitive drum 1 include a method of externally adding to the developing toner as in the present embodiment, and a method of providing an inorganic fine powder supply member in the cleaning device. There is no particular limitation.

  In this embodiment, as described above, 1.0 part by weight of strontium titanate (particle size: 110 nm) of perovskite type crystals is externally added to the toner of the developing device 4 as an inorganic fine powder and supplied onto the photosensitive drum. Was used. The developing method and developer used in this embodiment are not limited to this, and nonmagnetic one-component development, two-component development methods, and the like can also be suitably used.

  On the other hand, the sheet feeding roller 9 of the sheet feeding unit D is driven at a predetermined control timing, and the recording material (transfer sheet, OHP sheet, etc.) P as a recording medium stacked and stored in the sheet feeding cassette 8 is one. The sheets are separated and fed and sent to a registration roller (registration roller) 10. The registration roller 10 controls the skew correction of the recording material P and the transfer timing of the toner image from the photosensitive drum 1 to the recording material P. The registration roller 10 controls the leading edge of the recording material P fed from the paper feed cassette 8. Receive and stop. Then, the recording material P is introduced into a transfer nip portion T which is a pressure contact portion between the photosensitive drum 1 and a medium resistance transfer roller (transfer means) 5 by a registration roller 10 which is rotationally driven at a predetermined control timing. The While the recording material P is nipped and conveyed through the transfer nip T, the transfer roller 5 is applied with a transfer bias having a predetermined potential opposite to the toner charging polarity from the transfer bias power source S3. As a result, the toner image formed on the surface of the photosensitive drum 1 is electrostatically transferred sequentially onto the surface of the recording material P.

  The recording material P that has exited the transfer nip T is separated from the surface of the photosensitive drum 1 and guided by a guide member 11 to be heated by a heat fixing roller 12a of the image heat fixing device 12 serving as a fixing unit and a predetermined pressure applied thereto. Is introduced into the fixing nip N between the pressure roller 12b and the pressure roller 12b brought into contact with each other. The recording material P is nipped and conveyed by the fixing roller 12a and the pressure roller 12b in the fixing nip portion N, and receives heat and pressure in the conveyance process. As a result, the toner image is fixed on the surface of the recording material P as a fixed image. Then, the recording material P that has exited the fixing nip N is discharged as an image formed product (copy, print) to the discharge tray 14 by the discharge roller 13.

  Further, the transfer residual toner remaining on the surface of the photosensitive drum 1 after separation of the recording material is removed by a cleaning device (cleaning means) 6. The photosensitive drum 1 whose surface has been cleaned is repeatedly used for image formation.

  In the present embodiment, the photosensitive drum 1 and some processing means acting on the photosensitive drum 1 are provided as the process cartridge 15. Specifically, the photosensitive drum 1, the charging roller 2, the developing device 4, and the cleaning device 6 are integrally assembled in the cartridge frame 15a and detachably attached to the image forming unit A. As a cartridge to be used.

(2) Cleaning device 6
The cleaning device 6 will be described with reference to FIG. The cleaning device 6 is a blade cleaning device using an elastic cleaning blade (elastic blade) as a photosensitive member cleaning member.

  The cleaning device 6 includes a cleaning blade 6a supported by a sheet metal 6f, a toner collection sheet 6b, a waste toner collection container 6c, a brush roller (cleaning brush) 6d as a rotating member (cleaning auxiliary member), a solid lubricant 6i, and the like. It is configured.

  The cleaning blade 6a is made of polyurethane rubber that is integrally held at the tip of the sheet metal 6f, and the blade edge is counter-contacted with the photosensitive drum 1 under a condition of a predetermined intrusion amount and set angle to perform cleaning. A nip portion Bnip is formed. The rubber hardness is preferably 50 to 85 ° (JIS A). More preferably, it is 60 to 80 ° (JIS A).

  In this embodiment, a cleaning blade 6a having a urethane rubber of 70 ° (JIS A) is used, the setting angle = 22 °, and the penetration amount is in the range of 0.5 to 1.3 mm, and the photosensitive drum 1 of the cleaning blade 6a. The contact pressure to be in the range of 10 to 50 g / cm. The contact pressure is preferably 10 to 50 g / cm. When it is less than 10 g / cm, cleaning failure due to slipping of toner tends to occur. Further, when it exceeds 50 g / cm, it is difficult to obtain satisfactory durability due to the lack of the cleaning blade 6a.

  The brush roller 6d is disposed in contact with the photosensitive drum 1 upstream of the contact position (cleaning blade nip portion) of the cleaning blade 6a in the photosensitive drum rotation direction (image carrier rotation direction).

The brush roller 6d is formed by weaving conductive brush fibers in a base fabric and winding it on a 6mm diameter cored bar 6g to form a 16mm diameter brush roller. In this example, an acrylic conductive yarn having a thickness of 6 denier is used as the conductive brush fiber, and the fiber density is 50K / cm ² and is embedded in a base fabric with a W weave. Winding is performed so as to ensure conduction with the cored bar 6g. The contact amount α = 1 mm with respect to the photosensitive drum 1 is in contact with the contact width (contact nip portion width Lnip) = 7 mm in the rotation direction of the photosensitive drum. The brush roller 6d is rotationally driven at a peripheral speed (first peripheral speed) VB in the counterclockwise direction of the arrow. That is, the photosensitive drum 1 and the cleaning brush 6d move in the same direction at the contact portion and rub against each other.

  The brush roller 6d is connected to a drive source M such as a stepping motor controlled by the controller unit C, and can arbitrarily change the rotation speed. In this embodiment, the peripheral speed ratio with the surface of the photosensitive drum 1 is 110%.

  The solid lubricant 6i is preferably a metal soap such as zinc stearate, aluminum stearate, calcium stearate. In this embodiment, a zinc stearate rod (a rod-like block body long in the longitudinal direction of the brush roller 6d) is used as the solid lubricant 6i.

  The solid lubricant 6i is held by a holder (not shown), and the holder is moved and urged by the spring member 6h in the direction of the brush roller 6d, thereby pressing the solid lubricant 6i against the brush roller 6d. The contact is made with pressure. The solid lubricant 6i in contact with the brush roller 6d is rubbed and scraped little by little as the brush roller 6d rotates, and adheres to the brush roller 6d. Then, the lubricant adhering to the brush roller 6d is applied to the surface of the photosensitive drum 1 as the rotating photosensitive drum 1 and the brush roller 6d rub against each other. The solid lubricant 6i, the holder, and the spring member 6h are a lubricant application mechanism that applies the solid lubricant to the surface of the photosensitive drum 1 via the brush roller 6d that is a rotating member.

  The function of the solid lubricant (metal soap) applied to the surface of the photosensitive drum 1 is to coat the surface of the photosensitive drum 1 and protect it from discharge damage. For that purpose, it is necessary to apply the lubricant uniformly to the surface of the photosensitive drum 1 without unevenness. Where the lubricant film is not formed or insufficient, the surface of the photosensitive drum 1 is subjected to discharge damage due to direct charging, thereby inducing image flow / filming.

  However, in order to sufficiently supply the lubricant to the surface of the photosensitive drum 1, the solid lubricant 6 i is reduced in hardness to be easily scraped, or the contact pressure of the brush roller 6 d on the solid lubricant 6 i is increased. Problems also arise when measures such as increasing the scraping ability are taken. That is, the solid lubricant becomes a lump of powder and is likely to be supplied to the surface of the photosensitive drum 1, and not only uniform coating is possible, but also the cleaning blade 6 a may be locally damaged, resulting in poor cleaning. There is.

  Factors that determine the application capability of the solid lubricant by the brush roller 6d include the hardness of the solid lubricant 6i, the hardness of the hair of the brush roller 6d, and the flocking density. In the present invention, in order to supply the solid lubricant uniformly to the surface of the photosensitive drum 1 and not to supply it excessively, the following configuration is adopted.

  That is, inorganic fine powder is supplied to the brush roller 6d, which is a rotating member, and a cleaning nip portion (hereinafter referred to as a nip portion) Bnip. The inorganic fine powder is a powder whose particle shape is cubic and / or rectangular parallelepiped and whose primary particles have a particle size of 30 to 300 nm.

  With this configuration, the solid lubricant 6i is rubbed on the brush roller 6d in a state where inorganic fine powder, strontium titanate of a perovskite crystal in this embodiment is supported, so that the solid lubricant is uniformly applied to the surface of the photosensitive drum 1. To prevent excessive supply.

  As described above, the inorganic fine powder has an excellent polishing effect, and has a particularly high ability to polish finely and finely. Since the inorganic fine powder is supported on the brush roller 6d and rubbed with the solid lubricant 6i, the solid lubricant 6i can be evenly and finely cut so as not to become a lump of powder.

  The means for supporting the inorganic fine powder on the brush roller 6d is arbitrary, but in this embodiment, as described above, the inorganic fine powder is supplied from the developing device 4 onto the surface of the photosensitive drum 1, It is the structure which collects it with the brush roller 6d. That is, the inorganic fine powder externally added to the developing toner of the developing device 4 is mixed with the toner for developing the electrostatic latent image and supplied to the surface of the photosensitive drum 1. The toner of the toner image on the photosensitive drum is electrostatically transferred onto the recording material P in the transfer process. However, since the inorganic fine powder has a charging polarity opposite to that of the toner, it is applied to the surface of the photosensitive drum 1. Easy to remain. The remaining inorganic fine powder is carried to the cleaning device 6 by the subsequent rotation of the photosensitive drum 1 and supplied to the brush roller 6d and the nip portion Bnip.

  The inorganic fine powder on the photosensitive drum 1 is basically collected by the brush roller 6d if the brush roller 6d is in contact with the photosensitive drum 1, but the photosensitive member of the brush roller 6d is more reliably collected. The penetration amount α with respect to the drum 1 is preferably in the range of 0.5 to 2.0 mm. The contact nip width Lnip (contact portion width, nip width) is preferably in the range of 2 to 10 mm.

  When the intrusion amount is less than 0.5 mm and the contact nip width is less than 2 mm, the portion where the brush fibers are in contact with the photosensitive drum 1 is reduced, and it is difficult to reliably carry the necessary inorganic fine powder.

  If the intrusion amount exceeds 2.0 mm, the fall of the brush fibers is promoted and long-term functions cannot be achieved. Further, the configuration in which the contact nip width Lnip exceeds 10 mm is not preferable because it leads to an increase in the diameter of the brush roller 6d.

  If the hardness of the solid lubricant 6i is too soft, it is not preferred that uneven shaving and excessive supply are likely to occur. Those having a pencil hardness of 2B or more are preferably used. Even if the solid lubricant 6i is somewhat hard and difficult to scrape, since the inorganic fine powder of perovskite crystal is carried on the brush roller 6d, the solid lubricant 6i is scraped finely and stably supplied onto the surface of the photosensitive drum 1. Is possible.

  For the above reason, the contact pressure of the brush roller 6d with respect to the solid lubricant 6i can be used at a lower level than before. As a result, it is possible to prevent the falling of the hair due to long-term use of the brush roller 6d and to extend the life of the member. For the above reason, the penetration amount of the brush roller 6d into the solid lubricant 6i is preferably 0.5 to 1.5 mm.

  Next, the function and effect at the nip portion Bnip will be described. The action of the cleaning blade 6a is to spread the solid lubricant uniformly applied by the brush roller 6d at the nip portion Bnip and form a film so as to completely cover the surface of the photosensitive drum 1. Further, the coating of the solid lubricant adsorbing the discharge product is removed by rubbing at the nip portion Bnip. In order not to cause image flow, it is necessary to remove discharge products adsorbed on the solid lubricant film. The scraping action of the discharge product is mainly performed by the cleaning blade 6a and is considered to be performed by rubbing with the cleaning blade 6a. The removal of the discharge product is effectively performed by supplying perovskite crystal inorganic fine powder to the nip portion Bnip.

(3) Image evaluation Image evaluation was performed with the above configuration. In the evaluation mode, a durability test of 50,000 sheets was performed intermittently for a chart with a printing rate of 5%.

  The test environment is high temperature and high humidity (30 ° C, 80%). As an indicator of uniform application of zinc stearate as a solid lubricant and reliable removal of discharge products, image flow / filming / cleaning blade damage Evaluated.

  The damage of the cleaning blade 6a is evaluated by the width (μm) × depth (μm) of the blade edge, and the larger this value, the worse the level.

  The evaluation results of Example 1 are shown in Table 1 of FIG. In Example 1, rectangular solid strontium titanate having excellent polishing ability is supported on the cleaning brush 6d as the inorganic fine powder, and the solid lubricant 6i is scraped off. Thereby, uniform polishing of the solid lubricant 6i is performed, and uniform application to the surface of the photosensitive drum 1 is achieved over a long period of time.

  In addition, since the solid lubricant film adsorbing the discharge product can be effectively removed at the nip portion Bnip, stable image formation that does not cause image flow throughout can be performed.

  By using the configuration of the first embodiment, it is possible to provide an image forming apparatus capable of uniformly and stably applying the solid lubricant to the photosensitive drum 1, reducing the load on the cleaning blade 6a, and ensuring long-term cleaning performance. It becomes possible.

  The solid lubricant 6i may be a higher fatty acid metal salt (so-called metal soap) other than zinc stearate used in this embodiment, or a solid wax mainly composed of an ester of a higher fatty acid and a higher alcohol. But it doesn't matter. The point is that the same effect can be obtained if a solid lubricant thin film can be formed by applying a fine powder obtained by scraping a block-like solid lubricant with a brush roller 6d. Can do.

[Comparative Example 1]
In this comparative example 1, the developer of the developing device 4 in Example 1 was used in which the perovskite crystal strontium titanate as the inorganic fine powder was not externally added.

  That is, an inorganic fine powder having a particle size of 30 to 300 nm of primary particles having a cubic shape and / or a rectangular parallelepiped shape is not supplied to both the brush roller 6d and the nip portion Bnip. Other configurations are the same as those in Example 1, and the results of the same evaluation are shown in Table 1 in FIG.

  In Comparative Example 1, uneven supply of the solid lubricant to the photosensitive drum 1 occurred, and partial image flow / filming was observed. The level of damage to the cleaning blade 6a was also bad.

  In the configuration of the present comparative example 1, the solid lubricant is not applied well to the surface of the photosensitive drum 1, and most of the solid lubricant enters the nip portion Bnip in a powder state, and the nonuniform powder damages the nip portion Bnip. give. Then, it is considered that edge cleaning and chattering of the cleaning blade 6a are induced, and effective spreading of the lubricant at the nip portion Bnip and proper removal of the discharge products are not performed.

[Example 2]
In the second embodiment, the brush roller 6d as a rotating member is configured such that the pass rate of the inorganic fine powder on the surface of the photosensitive drum (on the surface of the image carrier) changes before and after the brush roller (before and after the rotating member). Is.

  That is, in the second embodiment, the brush roller 6d having the configuration shown in FIG. 4 is used in the first embodiment. In the brush roller 6d, regions Lr where brush fibers are present and regions Lp where brush fibers are present are alternately provided in the roller circumferential direction. The region Lr where the brush fiber is present and the region Lp where the brush fiber is present are a region in which the inorganic fine powder is relatively easily retained and a region in which it is difficult to retain.

  When this brush roller 6d is used, in the region Lr where the brush fiber is present, the inorganic fine powder strontium titanate is scraped off from the surface of the photosensitive drum 1 and held on the brush fiber, and the solid lubricant 6i is uniformly polished. Has an effect. On the other hand, in the region Lp where there is no brush fiber, strontium titanate on the surface of the photosensitive drum 1 is passed as it is and efficiently supplied to the cleaning blade nip portion.

  By adopting such a brush roller configuration, the uniform polishing of the solid lubricant 6i with the inorganic fine powder and the rubbing at the nip portion Bnip can be efficiently performed, and more stable cleaning can be performed over a long period of time.

In Example 2, the brush fibers in the region Lr where the brush fibers are present were made of acrylic conductive yarn having a thickness of 6 denier, and the density was 100 K / cm ² . In the second embodiment, the ratio of the region Lr where the brush fiber is present to the region Lp where the brush fiber is present is approximately 1: 1, and the friction between the brush fiber-solid lubricant 6i and the nip portion Bnip is performed appropriately and efficiently. It is in a state to be called.

  The length in the roller circumferential direction of the region Lr where the brush fibers are present was 4 mm, and the length in the roller circumferential direction of the region Lp where the brush fibers were absent was also 4 mm. Other configurations are the same as those in Example 1, and the results of the same evaluation are shown in Table 1 in FIG.

  Compared to the results of Example 1, it can be seen that the damage level of the cleaning blade 6a is further improved. When the brush fiber density is uniform in the roller circumferential direction as in the brush roller 6d of the first embodiment, most of the inorganic fine powder is once scraped off from the surface of the photosensitive drum 1 by the brush roller. That is, in Example 1, the passing rate of the inorganic fine powder on the surface of the photosensitive drum before and after the brush roller is substantially constant. Therefore, the supply amount of the inorganic fine powder to the nip portion Bnip is smaller than that of the brush roller configuration of the second embodiment. Although the configuration of the first embodiment does not cause a problem in actual use, in order to achieve long-term more stable cleaning using a highly durable photosensitive drum as an image carrier, the configuration of the second embodiment is used. It is preferable to take. That is, it is preferable to adopt the configuration as in the second embodiment, in which the inorganic fine powder can be supplied in a well-balanced manner to both the solid lubricant 6i and the nip portion Bnip.

[Comparative Example 2]
In Comparative Example 2, a brush roller 6d having the form shown in FIG. 5 was used in Example 1. That is, the brush roller 6d used in the present comparative example 2 is obtained by winding brush fibers on a core metal 6g in a spiral shape along the length of the core metal. As the brush fiber of the wound portion, an acrylic conductive yarn having a thickness of 6 denier / density of 100 K pieces / cm ² was used. Other configurations are the same as those in Example 1, and the results of the same evaluation are shown in Table 1 in FIG.

  In the configuration of Comparative Example 2, the solid lubricant 6i was not rubbed by the brush roller 6d, and the surface of the photosensitive drum 1 could not be uniformly supplied, and image flow unevenness occurred in the longitudinal direction. The level of damage to the cleaning blade 6a was also poor.

[Example 3]
In the third embodiment, the brush roller 6d having the configuration shown in FIG. 6 is used in the first embodiment. That is, the brush roller 6d used in the present embodiment is provided with regions Lr and sparse regions Lp with relatively high brush fiber density alternately in the circumferential direction. In the brush roller 6d, the region Lr where the brush fiber density is high and the region Lp where the brush fiber density is high are regions where the inorganic fine powder is relatively easy to hold and difficult to hold. The passing rate on the surface of the photosensitive drum changes.

The region Lr having a high fiber density is a 3 denier acrylic conductive yarn / density of 100 K / cm ² as a brush fiber, and the region Lp having a low fiber density is a 5 denier acrylic conductive yarn / density as a brush fiber. It was 10K / cm ² . Other configurations are the same as those in Example 1, and the results of the same evaluation are shown in Table 1 in FIG.

  By adopting the configuration of the third embodiment, similarly to the second embodiment (FIG. 4), the inorganic fine powder can be supplied in a well-balanced manner to both the solid lubricant 6i and the nip portion Bnip, and a long-term stable cleaning performance can be obtained. It was.

  In addition, the inventors have intensively studied and found that long-term cleaning performance is obtained and a more preferable configuration by satisfying the following conditions.

That is, the thickness of the brush fiber in the region Lr where the brush fiber density of the brush roller 6d is dense is Ar (denier) and the density is Br (K / cm ² ). Let Rr be the ratio of the dense region Lr to the entire brush region. The thickness of the brush fiber in the region Lp where the brush fiber density is sparse is Ap (denier), and the density is Bp (K / cm ² ). The ratio of the sparse area Lp to the entire brush area is Rp. The particle size (average particle size) of primary particles of the inorganic fine powder is C (μm). And
300 ≦ ArBr + ApBp ≦ 1200 (a)
ArBr> 5 ApBp (b)
5 <Rr / Rp <2.0 (c)
10 <ArBrC (d)
0.03 ≦ C ≦ 0.3 (e)
When satisfying the relational expressions (a) to (e), long-term cleaning performance was obtained, and it was found that the structure is more preferable. The results representing these relationships are shown in Table 2 of FIG.

  Here, the relational expressions (a) to (e) will be described. ArBr and ApBp are obtained by multiplying the thickness of the brush fiber by the brush fiber density, and the larger this value, the larger the area occupied by the brush fiber. That is, the larger this value is, the more inorganic fine powder on the surface of the photosensitive drum 1 is held on the brush roller 6d, and the smaller the value is, the higher the probability that it is allowed to pass through and supplied to the nip portion Bnip. The particle size of the inorganic fine powder is also related to this, and the smaller the particle size, the higher the probability that it passes through the brush roller 6d and is directly supplied to the nip portion Bnip. That is, in order to polish an appropriate amount of inorganic fine powder having a small particle size on the brush roller 6d and polish the solid lubricant 6i, it is necessary to increase the value of ArBr and increase the chance of contact between the brush fiber and the inorganic fine powder. is there.

  Based on the above, the above relational expression will be described. When ArBr + ApBp is less than 300 and 10 <ArBrC, the action of carrying the inorganic fine powder on the brush fiber and uniformly polishing the solid lubricant 6i is not sufficiently achieved (Tables 2-No 11, 20, 21, 22).

  On the contrary, if ArBr + ApBp exceeds 1200, polishing of the solid lubricant 6i becomes excessive and supply of the inorganic fine powder to the nip portion Bnip becomes insufficient (Table 2-No25).

  However, these are related not only to the value of ArBr + ApBp but also to the balance of the brush fiber conditions of the dense region Lr and the sparse region Lp, and the ratio of the occupied region.

  Under the condition of ApBp <ArBr ≦ 5ApBp (Table 2-No3, 5), the difference between the brush fiber density dense region Lr and the sparse region Lp is small. Therefore, both the solid lubricant 6i by the inorganic fine powder and the nip portion Bnip which are the target of the present invention cannot be properly rubbed, and the function separation function by the brush roller 6d cannot be performed.

  This is also related to the brush fiber occupancy ratios of the respective regions Lr and Lp. Under the condition of 0.5 ≧ Rr / Rp (Table 2-No. 7), the solid lubricant 6i is not sufficiently polished. When Rr / Rp ≧ 1.5 (Table 2-No. 8 and 9), the inorganic fine powder supplied to the nip portion Bnip becomes insufficient.

  For the above reasons, when satisfying the relations (a) to (e), the inorganic fine powder can be appropriately supplied to both the solid lubricant 6i and the nip portion Bnip, and long-term cleaning performance can be obtained. It is done.

  Furthermore, the following matters can be cited as factors that determine whether the inorganic fine powder is held by the brush fibers or passes as it is. That is, the circumferential speed difference of the region Lp where the difference in the peripheral speed between the photosensitive drum 1 and the brush roller 6d, the contact portion width (nip width) of the brush roller 6d with respect to the photosensitive drum 1, and the brush fiber density of the brush roller 6d is sparse. Also comes into play.

Accordingly, the moving speed of the photosensitive drum 1 (moving speed of the image carrier surface (process speed)) is Vd (mm / sec), and the peripheral speed of the brush roller is Vb (mm / sec). Further, the contact nip width of the brush roller 6d with respect to the photosensitive drum 1 is Lnip (mm), and the length of the brush roller 6d in the region Lp where the brush fiber density is sparse is Lp (mm). And in addition to the above relational expressions (a) to (e),
Vb / Vd <Lp / Lnip <1.5 Vb / Vd (f)
2 ≦ Lnip ≦ 10 (g)
By satisfying this relationship, the dense / sparse characteristics of the brush fiber density in the circumferential direction of the brush roller 6d can be stably extracted.

  With regard to the rotation direction of the brush roller 6d, the embodiment is configured to move in the same direction at the contact portion with the photosensitive drum 1. If it is set to move in the opposite direction, there are too many opportunities for the brush fibers to rub against the surface of the photosensitive drum 1, and the action of passing the inorganic fine powder directly to the nip portion Bnip cannot be performed. Vb / Vd is a peripheral speed ratio between the photosensitive drum 1 and the brush roller 6d. The larger this value, the faster the brush roller 6d moves with respect to the photosensitive drum 1, so that the brush fibers move on the surface of the photosensitive drum 1. This is a direction where the chance of rubbing increases. That is, under the condition that the value of Vb / Vd is large, unless the Lp of the brush roller 6d is set longer than Lnip, the effective supply of the inorganic fine powder to the nip portion Bnip which is the object of the present invention is achieved. Disappear. In other words, when the brush roller 6d having a narrow Lp is used, the value of Vb / Vd cannot be increased. Here, Lnip is a value obtained on the assumption that brush fibers exist in the entire area of the brush roller as shown in FIG. For the above reasons, when Vb / Vd> Lp / Lnip, the supply of the inorganic fine powder to the nip portion Bnip was insufficient, and a sufficient effect was not obtained (Tables 2-No. 16 and 17). On the contrary, if Lp / Lnip> 1.5Vb / Vd, Lp becomes too long, excessive supply to the nip portion Bnip, and insufficient sliding of the solid lubricant 6i occur (Tables 2-No 14, 15, 19). . The range of Lnip comes from the recoverability of the inorganic fine powder and the durability of the member as described in Example 1.

  As described above, by satisfying the relations (a) to (g), the inorganic fine powder can be appropriately supplied to both the solid lubricant 6i and the nip portion Bnip. As a result, uniform application of the solid lubricant to the surface of the photosensitive drum 1 and reliable removal of the solid lubricant film adsorbing the discharge products at the nip portion Bnip can be effectively performed, and long-term cleaning performance is obtained. It is done.

[Example 4]
In the fourth embodiment, the brush roller 6d having the configuration shown in FIG. 8 is used in the first embodiment. That is, the brush roller 6d used in the present embodiment has regions (conductive brush regions) La where the brush fibers are conductive and regions (insulating brush regions) Lb where the brush fibers are conductive alternately provided in the circumferential direction, and A bias having a polarity opposite to the polarity of the inorganic fine powder is applied. In the present embodiment, the former is a dense region and the latter is a sparse region relative to the fiber brush density of the conductive brush region La and the fiber brush density of the insulating brush region Lb. In the brush roller 6d, the conductive brush region La and the insulating brush region Lb are a region where the inorganic fine powder is relatively easily held and a region where the inorganic fine powder is relatively difficult to hold. The passing rate above changes.

In the conductive brush region La, an acrylic conductive yarn having an electric resistance value of about 10 Ωcm was used as the brush fiber, and the fiber thickness was 6 denier / fiber density 100 K / cm ² . Insulating brush region Lb uses PET as the brush fiber, and has a fiber thickness of 10 denier / fiber density of 10K / cm ² . The ratio of the conductive brush region La and the insulating brush region Lb was 1: 1.

  In this embodiment, a bias is applied to the brush roller 6d, and the inorganic fine powder is positively collected on the brush in the conductive brush region Lb. In the present example, since strontium titanate, which is an inorganic fine powder, has a positive polarity, a bias of −500 V was applied to the cored bar 6g of the brush roller 6d from the power supply unit S4. Other configurations are the same as those in Example 1, and the same evaluation is performed. The results are shown in Table 1 in FIG.

  By adopting the configuration of this example, it was possible to reliably carry the inorganic fine powder in the conductive brush region La, and it was possible to stably evenly polish the solid lubricant 6i more stably. In addition, since the insulating brush region Lb does not electrostatically adsorb strontium titanate perovskite crystals, which are inorganic fine powders, and the fiber density is sparse, it can be sufficiently supplied to the nip portion Bnip. Due to these functions and effects, a stable cleaning performance was obtained for a long period of time in this example.

[Example 5]
In this embodiment, as shown in FIG. 9, the rotating member (cleaning auxiliary member) includes a region H where the contact pressure to the photosensitive drum 1 is relatively strong (high) and a region S where the contact pressure is weak (low). An elastic roller (cleaning roller) 6e provided alternately in the direction was used. In the elastic roller 6e, the strong region H and the weak region S are a region where the inorganic fine powder is relatively easily held and a region where the inorganic fine powder is relatively difficult to hold, and on the photosensitive drum surface of the inorganic fine powder before and after the elastic roller. The passing rate of will change.

  Specifically, the elastic roller 6e used in the present embodiment is a roller having a diameter of 16 mm, in which two kinds of elastic members H and S are alternately bonded to the roller core 6g in the circumferential direction of the roller.

  The elastic member H has an Asker C hardness of 70 °, the elastic member S has an Asker C hardness of 20 °, the elastic member H has a penetration into the photosensitive drum 1 of 0.7 mm, and the elastic member S has a photosensitive member. The amount of penetration into the drum 1 was 0.3 mm.

  Examples of the elastic material include acrylonitrile-butadiene rubber (NBR), styrene butadiene rubber, butadiene rubber, and ethylene propylene rubber. Further, chloroprene rubber, hydrin rubber, chlorosulfonated polyethylene, chlorinated polyethylene, acrylonitrile butadiene rubber, acrylic rubber, fluorine rubber, urethane rubber, and the like can be given. Alternatively, conductivity may be imparted by dispersing metal oxides such as titanium oxide and tin oxide, carbon black, aluminum powder, nickel powder, and the like as conductive materials in these materials.

  The amount of penetration of the elastic roller 6e into the solid lubricant 6i was 0.5 mm at the elastic member H part. The elastic roller 6 e rotates in the same direction at the contact portion with the photosensitive drum 1, and has a peripheral speed ratio of 105% with respect to the photosensitive drum 1. Other configurations are the same as those in Example 1, and the results of the same evaluation are shown in Table 1 in FIG.

  In this embodiment, in the portion H where the hardness of the elastic member is high, the contact pressure against the photosensitive drum 1 becomes strong, and the peelability of the inorganic fine powder from the surface of the photosensitive member becomes high. Since the solid lubricant 6i is rubbed with the inorganic fine powder supported, fine polishing and uniform application are possible.

  In the present embodiment, the penetration amount of the elastic roller 6e into the solid lubricant 6i is 0.5 mm at the elastic member H, but it can be suitably used as long as it is in the range of 0.3 to 1.0 mm. If the thickness is less than 0.3 mm, the contact state becomes unstable and the uniform polishing / coating property is deteriorated. Conversely, if it exceeds 1.0 mm, the solid lubricant is excessively supplied, which is not preferable.

  On the other hand, in the S portion where the hardness of the elastic member is low, the contact pressure with respect to the photosensitive drum 1 is weak, so the ability to peel off the inorganic fine powder from the surface of the photosensitive member is lowered, and the elastic roller portion passes as it is and is supplied to the nip portion Bnip. The probability that it will be increased. That is, as in the case where the rotating member is the brush roller 6d, the inorganic fine powder can be supplied to both the solid lubricant 6i and the nip portion Bnip in a well-balanced manner. Performance was obtained.

  In addition, the inventors have intensively studied and found that long-term cleaning performance is obtained and a more preferable configuration by satisfying the following conditions.

That is, the contact pressure in the region H where the contact pressure with respect to the photosensitive drum 1 is strong is Ps (gf / cm), and the contact pressure in the region S where the contact pressure with respect to the photosensitive drum 1 is weak is Pw (gf / cm). To do. The ratio of the surface area of the region H where the contact pressure is strong to the total surface area of the roller is Rs, and the ratio of the surface area of the region S where the contact pressure is weak is Rw. The peripheral speed of the elastic roller 6e is Vg (mm / sec), and the moving speed (process speed) of the surface of the photosensitive drum 1 is Vd (mm / sec). The contact nip width of the elastic roller 6e with respect to the photosensitive drum 1 is Lgnip (mm), and the circumferential length of the region S where the contact pressure of the elastic roller 6e is weak is Lw (mm). Further, the particle size (average particle size) of primary particles of the inorganic fine powder is C (μm). And
30 ≦ Ps + Pw ≦ 200 (h)
Ps> 10Pw (i)
0.5 <Rs / Rw <2.0 (j)
3 <PsC <50 (k)
0.03 ≦ C ≦ 0.3 (l)
Vg / Vd <Lw / Lgnip <1.5 Vg / Vd (m)
2 ≦ Lgnip ≦ 7 (n)
When satisfying the above relationship, it has been found that a long-term cleaning performance is obtained and the structure is more preferable. The results representing these relationships are shown in Table 3 in FIG.

  Here, the relational expressions (h) to (n) will be described. Ps and Pw are contact pressures of the elastic roller 6e with respect to the photosensitive drum 1 in the two regions H and S, respectively, and the larger the value, the more the inorganic fine powder on the surface of the photosensitive drum 1 is peeled off. Improves. Moreover, it means that the smaller the value is, the higher the probability that it is passed as it is and supplied to the nip portion Bnip. In addition, the particle size of the inorganic fine powder is related to this, and the smaller the particle size, the stronger the adhesion to the surface of the photosensitive drum 1, and the probability of passing through the elastic roller portion and being directly supplied to the nip portion Bnip. Get higher. That is, in order to carry an appropriate amount of inorganic fine powder having a small particle size on the elastic roller 6e and polish the solid lubricant 6i, it is necessary to increase the value of Ps and to enhance the peelability by the elastic roller 6e. Further, the larger the particle size of the inorganic fine powder, the higher the polishing ability. If the particle size exceeds 300 nm, the surface of the photosensitive drum 1 may be scratched. Therefore, 300 nm or less is preferably used. However, even when the thickness is 300 nm or less, scratches may occur if the contact pressure of the elastic roller 6e against the photosensitive drum 1 is strong.

  Based on the above, the above relational expression will be described. When Ps + Pw is less than 30 (Table 3-No1) and 3 ≧ PsC (Tables 3-No1, 12), the elastic roller 6e supports the inorganic fine powder and the solid lubricant 6i is uniformly polished. It will not be done. On the contrary, when Ps + Pw exceeds 200, the polishing of the solid lubricant becomes excessive and the supply of the inorganic fine powder to the nip portion Bnip becomes insufficient (Table 3-No23). Further, under the condition of PsC ≧ 50 (Table 3-No. 17), scratches were generated on the photoreceptor surface.

  However, these are related not only to the value of Ps + Pw, but also to the balance of the contact pressure of the region H where the contact pressure is strong and the region S where the contact pressure is weak, and the proportion of the region occupied. Under the condition of Pw <Ps ≦ 10Pw (Table 3-No. 4), the difference between the respective regions is small, and the sliding of both the solid lubricant 6i and the nip portion Bnip with the target inorganic fine powder cannot be performed appropriately. . For this reason, a function-separated function based on the circumferential characteristics of the elastic roller cannot be performed.

  This is also related to the surface area ratio of each region. Under the condition of 0.5 ≧ Rs / Rw (Table 3-No. 7), the solid lubricant 6i is not sufficiently polished. When Rs / Rw ≧ 1.5 (Table 3-No10), the inorganic fine powder supplied to the nip portion Bnip is in a shortage direction.

For the above reasons,
30 ≦ Ps + Pw ≦ 200 (h)
Ps> 10Pw (i)
0.5 <Rs / Rw <2.0 (j)
3 <PsC <50 (k)
0.03 ≦ C ≦ 0.3 (l)
When the relationship is satisfied, the inorganic fine powder can be appropriately supplied to both the solid lubricant 6i and the nip portion Bnip, and long-term cleaning performance can be obtained.

  Further, the following matters can be cited as factors that determine whether the inorganic fine powder is peeled off by the elastic roller 6e or passes through as it is. That is, the peripheral speed difference between the photosensitive drum 1 and the elastic roller 6e, the contact portion width (nip width) of the elastic roller 6e with respect to the photosensitive drum 1, and the circumferential length of the region S where the elastic roller contact pressure is low are also related. Come.

Therefore, the moving speed of the photosensitive drum 1 is Vd (mm / sec), the peripheral speed of the elastic roller 6e is Vg (mm / sec), and the contact nip width of the elastic roller 6e with respect to the photosensitive drum 1 is Lgnip (mm). To do. Further, the length of the region S where the elastic roller contact pressure is weak in the circumferential direction of the elastic roller is Lw (mm). In addition to the above relational expressions (h) to (l),
Vg / Vd <Lw / Lgnip <1.5 Vg / Vd (m)
2 ≦ Lgnip ≦ 7 (n)
By satisfying this relationship, the characteristic of the contact pressure strength / weakness in the circumferential direction of the elastic roller 6e can be stably extracted.

  In this embodiment, the elastic roller 6e rotates in the same direction at the contact portion with the photosensitive drum 1 in the rotational direction. If it is set to move in the reverse direction, the area H where the contact pressure is strong has too many opportunities to rub against the surface of the photosensitive member, and the function of passing the inorganic fine powder directly to the nip portion Bnip cannot be performed. Vg / Vd is the peripheral speed ratio between the photosensitive drum 1 and the elastic roller 6e. The larger this value, the faster the elastic roller 6e moves with respect to the photosensitive drum 1, so that the elastic roller surface moves across the surface of the photosensitive drum. This is a direction where the chance of rubbing increases. That is, under the condition where the value of Vg / Vd is large, if the Lw region S where the contact pressure of the elastic roller 6e is weak is not set longer than Lgnip, the inorganic fine powder can be effectively supplied to the nip portion Bnip. It will not be made. In other words, when an elastic roller having a narrow Lw is used, the value of Vg / Vd cannot be increased. Here, Lgnip is a value formed when the region H where the contact pressure of the elastic roller 6e is strong contacts the photosensitive drum 1. For the above reasons, when Vg / Vd> Lw / Lgnip, the supply of the inorganic fine powder to the nip portion Bnip was insufficient (Table 3-No. 19 and 20), and a sufficient effect was not obtained. On the other hand, if Lw / Lgnip> 1.5 Vb / Vd (Tables 3-No. 18 and 22), Lw becomes too long, resulting in excessive supply to the nip portion Bnip and insufficient friction of the solid lubricant 6i. Further, if the range of Lgnip is less than 2 mm, it is not preferable because it leads to a decrease in the peelability of the inorganic fine powder.

  As described above, by satisfying the relations (h) to (n), the inorganic fine powder can be appropriately supplied to both the solid lubricant 6i and the nip portion Bnip. As a result, uniform application of the solid lubricant to the surface of the photosensitive drum, and reliable removal of the solid lubricant film adsorbing the discharge products at the nip portion Bnip can be effectively performed, and long-term cleaning performance can be obtained.

[Other matters]
1) In the present invention, the following method is used as a method of measuring the primary particle size (average particle size) of the inorganic fine powder. That is, 100 particle diameters were measured from a photograph taken with an electron microscope at a magnification of 50,000 times, and the average was obtained. The particle size was determined as (a + b) / 2, where a is the longest side of the primary particles and b is the shortest side.
2) The following method is used as the measuring method of the average particle diameter (weight average particle diameter (D4)) of the toner employed in the present invention. That is, “Coulter Counter Multisizer 3” (registered trademark, manufactured by Beckman Coulter, Inc.) is used. In addition, dedicated software “Beckman Coulter Multisizer 3 Version 3.51” (manufactured by Beckman Coulter, Inc.) for setting measurement conditions and analyzing measurement data is used. Then, the number of effective measurement channels was 25,000, the measurement data was analyzed, and the weight average particle diameter (D4) of the toner was calculated.

  3) The configuration of the elastic roller 6e is not limited to the configuration of the fifth embodiment as long as the inorganic fine powder can be supplied to both the solid lubricant 6i and the nip portion Bnip with a good balance.

  For example, the surface of the region where the inorganic fine powder is desired to pass as it is may be subjected to a fluorine treatment or the like having a high releasability so that it does not adhere to the surface. FIG. 11 shows the elastic roller 6e of this example. This elastic roller 6e is formed by forming an elastic member layer 6j in a roller shape around a roller core 6g, and intermittently forming fluorine treatment regions 6k on the surface of the elastic member layer 6j in the circumferential direction of the roller. That is, it is an elastic roller in which fluorine treatment regions 6k and untreated regions 6m are alternately provided in the circumferential direction of the elastic roller 6e. In the elastic roller 6e, the unprocessed area 6m and the fluorine-processed area 6k are an area where the inorganic fine powder is relatively easily held and an area where the inorganic fine powder is relatively difficult to hold. The passing rate above changes.

  4) FIG. 12 shows still another elastic roller configuration. The elastic roller 6e is an elastic porous roller, and regions X and Y in which the pore diameter of the porous member is relatively large are alternately provided in the circumferential direction. In the elastic porous roller 6e, the region X and the region Y are a region where the inorganic fine powder is relatively easily held and a region where the inorganic fine powder is relatively difficult to hold, and the surface of the photosensitive drum of the inorganic fine powder before and after the elastic porous roller. The passing rate above changes.

  5) Examples of the rotatable image carrier include a rotating drum type or a rotating belt type electrophotographic photosensitive member in an electrophotographic image forming apparatus. In addition, there is a rotating drum type or rotating belt type electrostatic recording dielectric in the electrostatic recording apparatus. Further, a magnetic recording magnetic body of a rotating drum type or a rotating belt type in a magnetic recording apparatus can be mentioned. The recording medium is a recording material such as transfer paper, an OHP sheet, or a label, or an intermediate transfer member of a rotating drum type or a rotating belt type.

Schematic diagram showing the schematic configuration of the image forming apparatus in the embodiment Enlarged view of the cleaning device Evaluation tables for Examples 1 to 5 and Comparative Examples 1 and 2 Structure explanatory drawing of the brush roller used in Example 2 Configuration explanatory diagram of the brush roller used in Comparative Example 2 Structure explanatory drawing of the brush roller used in Example 3 Evaluation table of Example 3 Structure explanatory drawing of the brush roller used in Example 4 Structure explanatory drawing of the cleaning apparatus used in Example 5 Evaluation table of Example 5 The figure which showed the other structural example of the elastic roller The figure which showed other structural examples of the elastic roller

Explanation of symbols

  A .. Image forming unit, B .. Document reading unit, 21. Document platen glass, 1 ... Photosensitive drum (image carrier), 2 ... Charging unit, 3 ... Image exposure unit (laser scanner), 4 .... Developing means, 5 .... Transfer roller, 6 .... Cleaning device, 6a ... Cleaning blade, 6d ... Rotating member (brush roller), 6e ... Rotating member (elastic roller), 7 .... Pre-exposure lamp 12, Fixing device

Claims (10)

A rotatable image carrier, a toner image forming unit that forms a toner image on the image carrier, a transfer unit that transfers the toner image to a recording medium, and a cleaning that removes transfer residual toner from the surface of the image carrier. And an image forming apparatus comprising:
The cleaning unit rotates in contact with the image carrier on the upstream side in the image carrier rotation direction with respect to the cleaning blade that forms a nip portion with the image carrier and scrapes off the transfer residual toner. A rotation member, and a lubricant application mechanism that applies a solid lubricant to the surface of the image carrier via the rotation member,
The rotating member and the nip portion are supplied with inorganic fine powder having a particle shape of cubic and / or rectangular parallelepiped and having a primary particle size of 30 to 300 nm , and the rotating member has the inorganic fine powder. An image forming apparatus, wherein regions that are relatively easy to hold a body and regions that are difficult to hold are alternately provided in a circumferential direction . To claim 1, wherein said that the passage rate of the image bearing member on the surface of the inorganic fine powder is different in a region difficult to hold a relatively holding easily region the inorganic fine powder before and after the pre-Symbol rotary member The image forming apparatus described . The rotating member is a brush roller, and a region where the brush fine density is relatively dense and a region where the inorganic fine powder is relatively easy to hold and a region where the inorganic fine powder is relatively difficult to hold are alternately provided in the circumferential direction. The image forming apparatus according to claim 1 , wherein the image forming apparatus is an image forming apparatus. The thickness of the brush fibers in the dense area is Ar (denier), the density is Br (K / cm ² ), and the ratio of the dense area to the entire brush area is Rr. The thickness is Ap (denier), the density is Bp (K / cm ² ), the ratio of the sparse area to the entire brush area is Rp, the peripheral speed of the brush roller is Vb (mm / sec), and the image is carried The moving speed of the body surface is Vd (mm / sec), the contact nip width of the brush roller with respect to the image carrier is Lnip (mm), and the length of the sparse area in the circumferential direction of the brush roller is Lp (mm) And the particle diameter of the primary particles of the inorganic fine powder is C (μm),
300 ≦ ArBr + ApBp ≦ 1200
ArBr> 5 ApBp
0.5 <Rr / Rp <2.0
10 <ArBrC
0.03 ≦ C ≦ 0.3
Vb / Vd <Lp / Lnip <1.5Vb / Vd
2 ≦ Lnip ≦ 10
The image forming apparatus according to claim 3 , wherein the relationship is satisfied.   The rotating member is a brush roller, and a region in which the brush fiber is electrically conductive and a region in which insulation is provided are alternately provided in the circumferential direction as a region where the inorganic fine powder is relatively easily held and a region where the inorganic fine powder is relatively difficult to hold. The image forming apparatus according to claim 3, wherein a bias having a polarity opposite to that of the inorganic fine powder is applied.   The rotating member is an elastic roller, and a region in which the contact pressure to the image carrier is relatively strong and a region in which the inorganic fine powder is relatively easy to hold and hard to hold are circumferential directions. The image forming apparatus according to claim 3, wherein the image forming apparatus is provided alternately. The contact pressure of the strong region is Ps (gf / cm), the contact pressure of the weak region is Pw (gf / cm), and the ratio of the surface area of the strong region to the total surface area of the roller is Rs. The ratio of the area occupied by the surface area is Rw, the peripheral speed of the elastic roller is Vg (mm / sec), the moving speed of the image carrier surface is Vd (mm / sec), and the contact nip of the elastic roller with respect to the image carrier When the part width is Lgnip (mm), the length of the weak region in the circumferential direction of the elastic roller is Lw (mm), and the particle size of the primary particles of the inorganic fine powder is C (μm),
30 ≦ Ps + Pw ≦ 200
Ps> 10Pw
0.5 <Rs / Rw <2.0
3 <PsC <50
0.03 ≦ C ≦ 0.3
Vg / Vd <Lw / Lgnip <1.5 Vg / Vd
2 ≦ Lgnip ≦ 7
The image forming apparatus according to claim 6 , wherein the relationship is satisfied.   The rotating member is an elastic porous roller, and a region having a relatively large pore diameter and a region having a relatively small pore diameter are alternately arranged in the circumferential direction as a region where the inorganic fine powder is relatively easily held and a region where the inorganic fine powder is relatively difficult to hold. The image forming apparatus according to claim 3, wherein the image forming apparatus is provided. The toner image forming means has a charging means for uniformly charging the surface of the image carrier, and the charging means is connected to a roller-type charging member arranged in contact with or close to the surface of the image carrier. the image forming apparatus according to claim 1, characterized in that for applying a bias obtained by superimposing DC 8. The image forming apparatus according to any one of claims 1 to 9, wherein the image bearing member, characterized in that it is an electrophotographic photosensitive member of the rotating drum or rotating belt type.