JP2005128379A - Cleaning device, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent toner from passing through the gap between a cleaning blade and a surface of an image carrier and to suppress faulty cleaning. <P>SOLUTION: The cleaning blade has a contact part 15 which comes in contact with a peripheral surface of the image carrier 2 disposed in such a way that it can rotate around its axial center in parallel with the axial center of the image carrier 2, and a toner blocking face 17 forming a space which expands from the contact part 15 toward the upstream side of the image carrier 2 in the rotative direction between the toner blocking face 17 and the surface of the image carrier 2. A high friction part 18 having a higher coefficient of friction than a material forming the cleaning blade 13 is attached to the toner blocking face 17 of the cleaning blade so that turnover of toner ta which is in contact with the toner blocking surface 17 to the surface of the image carrier 2 is suppressed in rotation of the image carrier 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cleaning device, a process cartridge, and an image forming apparatus.

  Some electrophotographic image forming apparatuses include a cleaning device that removes toner remaining on the surface of a photosensitive drum (residual toner) during an image forming operation.

  Some of such cleaning devices include a cleaning blade disposed so as to contact the surface of the photosensitive drum. The cleaning blade is made of an elastic material, and scrapes off residual toner on the surface of the photosensitive drum as the photosensitive drum rotates.

  For example, an image forming apparatus including a cleaning device having a blade provided in contact with an image carrier, a toner receiving unit that receives toner scraped off by the blade, and a toner removing unit that removes the received toner (For example, refer to Patent Document 1).

  Also, residual toner on the image carrier after passing through the transfer process is recovered by electrostatic adsorption force due to a potential difference between the surface of the image carrier after passing through the transfer process and the surface of the rotating body in contact with the surface. There is an image forming apparatus configured to do so (for example, see Patent Document 2).

JP 2002-278401 A JP-A-8-314346

  However, in the conventional technology, toner may slip through between the surface of the photosensitive drum and the cleaning blade. In such a case, the surface of the photosensitive drum cannot be satisfactorily cleaned. This also occurs in the technique described in Patent Document 1 described above.

  An object of the present invention is to prevent toner from slipping through between the cleaning blade and the surface of the image carrier, thereby suppressing the occurrence of defective cleaning.

According to a first aspect of the present invention, there is provided a cleaning device according to the present invention, wherein the contact portion between the contact portion contacting the outer peripheral surface of the image carrier and the outer peripheral surface of the image carrier is directed upstream from the contact portion in the moving direction of the image carrier. A cleaning blade having a toner blocking surface that forms a space that expands, and an outer periphery of the image carrier of toner that is provided on the toner blocking surface and contacts the toner blocking surface when the image carrier moves A high friction part having a higher friction coefficient than the material forming the cleaning blade so as to suppress movement relative to the surface.

  Therefore, even when the image carrier moves during the image forming operation, the image carrier can be moved without increasing the frictional force acting between the image carrier and the cleaning blade as the image carrier moves. It is possible to prevent the cleaning blade from being pushed up from the surface of the image carrier due to the rotation of the toner. Accordingly, it is possible to prevent toner from slipping between the cleaning blade and the surface of the image carrier.

  According to a second aspect of the present invention, in the cleaning device according to the first aspect, the high friction portion is formed by coating the toner blocking surface with a high friction material having a higher friction coefficient than the material forming the cleaning blade. Is provided.

  Therefore, the operation of the invention according to claim 1 can be easily obtained in practice.

  According to a third aspect of the present invention, in the cleaning device according to the first aspect, the high friction portion is provided by roughening a surface property of the toner blocking surface.

  Therefore, the operation of the invention according to claim 1 can be easily obtained in practice.

  According to a fourth aspect of the present invention, a process cartridge includes the cleaning device according to the first, second, or third aspect and an image carrier, and is detachably supported with respect to the image forming apparatus main body.

  Therefore, for example, when the process cartridge of the present invention is applied to an image forming apparatus, handling in units of process cartridges becomes possible. Thereby, the maintenance work of the cleaning device by the user can be facilitated and good cleaning performance can be maintained.

  According to a fifth aspect of the present invention, an image forming apparatus includes the process cartridge according to the fourth aspect.

  Therefore, for example, when a component included in the process cartridge fails, it becomes possible to handle the process cartridge unit. Thereby, the maintenance work of the cleaning device by the user can be facilitated and good cleaning performance can be maintained.

  An image forming apparatus according to a sixth aspect of the invention includes the cleaning device according to the first, second, or third aspect.

  Therefore, it is possible to obtain an image forming apparatus that exhibits the operation of the first, second, or third aspect.

  According to a seventh aspect of the present invention, in the image forming apparatus according to the fifth or sixth aspect, the toner comprises a release agent dispersed in an aqueous medium in which a prepolymer, a colorant, and resin fine particles are present. It is formed by a polyaddition reaction of the toner composition.

  Here, when a toner having an average particle size distribution of 7 μm or less, a polymerized toner manufactured using a polymerization method, or a polyester-based spherical (or almost spherical) toner is used, cleaning of residual toner by a cleaning blade is performed. Becomes very difficult.

  Therefore, by using the toner of the present invention, the action of the invention according to claim 5 or 6 can be obtained more reliably.

  According to the cleaning device of the first aspect, even when the image carrier moves during the image forming operation, the frictional force acting between the image carrier and the cleaning blade in accordance with the movement of the image carrier. Without the increase, it is possible to prevent the cleaning blade from being pushed up from the surface of the image carrier by the rotation of the toner accompanying the movement of the image carrier, so that the toner is interposed between the cleaning blade and the surface of the image carrier. It is possible to prevent slipping through and prevent the occurrence of defective cleaning.

  According to the invention of claim 2, in the cleaning device of claim 1, the effect of the invention of claim 1 can be easily obtained in practice.

  According to the invention of claim 3, in the cleaning device of claim 1, the effect of the invention of claim 1 can be easily obtained practically.

  According to the process cartridge of the fourth aspect of the present invention, for example, when the process cartridge of the present invention is applied to an image forming apparatus, the process cartridge can be handled. Thereby, the maintenance work of the cleaning device by the user can be facilitated and good cleaning performance can be maintained.

  According to the image forming apparatus of the fifth aspect of the present invention, for example, when a component included in the process cartridge breaks down, the process cartridge unit can be handled, so that the maintenance work of the cleaning device by the user is facilitated. Good cleaning performance can be maintained.

  According to the image forming apparatus of the invention described in claim 6, it is possible to obtain an image forming apparatus that exhibits the effect of the invention described in claim 1, 2, or 3.

  According to the seventh aspect of the present invention, in the image forming apparatus according to the fifth or sixth aspect, a toner having an average particle size distribution of 7 μm or less, a polymerized toner produced using a polymerization method, a polyester-based sphere ( In the case of using a substantially spherical toner, it is very difficult to clean the remaining toner with a cleaning blade. However, the use of the toner of the present invention makes the effects of the invention of claim 5 or 6 more effective. You can definitely get it.

  A first embodiment for carrying out the present invention will be described with reference to FIGS. This embodiment shows an application example to an image forming apparatus. Although not particularly illustrated, the image forming apparatus according to the present embodiment includes a paper path from a paper feed unit that holds transfer paper for forming an image to a paper discharge unit via a printer engine (see FIG. 1). ing.

  Here, FIG. 1 is a schematic view showing a printer engine in the image forming apparatus of the first embodiment for carrying out the present invention. As shown in FIG. 1, the printer engine 1 includes a photosensitive drum 2 serving as an image carrier that is disposed substantially at the center of the printer engine 1.

  Around the photosensitive drum 2, a charging roller 3 for charging the photosensitive drum 2 with a uniform charge, an exposure device (not shown) for forming an electrostatic latent image on the photosensitive drum 2, and an electrostatic latent image And a transfer belt 5 for transferring the toner image on the photosensitive drum 2 onto a transfer sheet.

  The image forming apparatus includes a toner supply device (not shown) that supplies toner to the developing device 4 via a toner supply port (not shown) provided in the developing device 4. The developing device 4 includes a sleeve 6 that supplies the supplied toner to the photosensitive drum 2.

  Here, the toner held by the developing device of the present embodiment will be exemplified. The toner of the present embodiment can be manufactured by the method described below. The toner manufacturing method is not limited to this.

  In producing the toner, first, a toner composition is prepared. In this embodiment, a toner composition is prepared by dissolving a toner raw material made of a polyester resin (prepolymer) having a resin, a colorant, a wax, a charge control agent, and an isocyanate group in an organic solvent such as ethyl acetate. . Here, the prepolymer means a polymer having two or more reactive groups in one molecule of the base polymer.

  Subsequently, the toner composition and amines described above are added to an aqueous medium containing a surfactant, a viscosity modifier, and resin fine particles, and dispersed by shearing force to form an emulsified state.

  And in order to accelerate | stimulate the expansion | extension and crosslinking reaction by reaction with an isocyanate group and amines, it heats with respect to a reaction system and matures a system. As an example, a method of gradually raising the temperature of the entire system and evaporating and removing the organic solvent in the droplets (desolvation) can be used. Thereby, particulate toner (toner particles) can be obtained.

  Further, the foreign matters (surfactant, viscosity modifier, etc.) remaining on the surface of the toner particles thus obtained are removed by alkali washing or water washing, and the obtained toner particles are recovered by filtration. ,dry.

  In addition, an external additive treatment is carried out in which 0.1 to 5.0 parts by weight of external additive fine particles (silica, titania, alumina, etc.) are externally added to the dried toner particles by a mixer as necessary. Do.

  Hereinafter, as an example, a method for producing toner used in the image forming apparatus of the present embodiment will be described. The toner that can be used in the above-described image forming apparatus and the method for producing the toner are not limited to this.

  In the production of the toner, first, 60 parts of polyester a, 15.4 parts of an isocyanate group-containing prepolymer and 78.6 parts of ethyl acetate are placed in a beaker and stirred to dissolve.

  Here, production of polyester a used in the present embodiment will be exemplified. Although not shown in particular, in the production of polyester a, first, 690 parts of a bisphenol A ethylene oxide 2-mol adduct (hereinafter, parts indicate parts by weight) in a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introduction pipe. Then, 256 parts of terephthalic acid was polycondensed at 230 ° C. under normal pressure for 8 hours, then reacted for 5 hours at a reduced pressure of 10 to 15 mmHg, then cooled to 160 ° C., and 18 parts of phthalic anhydride was added thereto and reacted for 2 hours. Let Thereby, unmodified polyester a can be obtained.

  Next, production of an isocyanate group-containing prepolymer as the prepolymer used in the present embodiment will be described. Although not shown in the drawings, in the production of the isocyanate group-containing prepolymer, first, 800 parts of bisphenol A ethylene oxide 2-mol adduct, 180 parts of isophthalic acid, terephthalic acid are added in a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introduction pipe. 60 parts of acid and 2 parts of dibutyltin oxide are added and reacted at 230 ° C. for 8 hours at normal pressure. The reaction is further reacted for 5 hours while dehydrating at a reduced pressure of 10-15 mmHg. Subsequently, after the reaction product described above is cooled to 160 ° C., 32 parts of phthalic anhydride is added to the reaction product and reacted for 2 hours. Furthermore, after cooling the above-mentioned reaction product to 80 ° C., 170 parts of isophorone diisocyanate is added in ethyl acetate and reacted for 2 hours. Thereby, an isocyanate group-containing prepolymer (1) can be obtained.

  Returning to the toner production method, 10 parts of rice WAX (melting point: 83 ° C.) as a release agent and 4 parts of copper phthalocyanine blue pigment (cyan pigment) were added, and the mixture was added at 60 ° C. using a TK homomixer. The mixture was stirred at 12000 rpm, and uniformly dissolved and dispersed.

  In addition, 2.7 parts of ketimine compound was added and dissolved. This is designated as toner material solution (1).

  Here, production of the ketimine compound used in the present embodiment will be exemplified. Although not particularly shown, in the production of the ketimine compound, 30 parts of isophoronediamine and 70 parts of methyl ethyl ketone are charged in a reaction vessel equipped with a stirrer and a thermometer and reacted at 50 ° C. for 5 hours. Thereby, a ketimine compound (1) can be obtained.

  Subsequently, 306 parts of ion-exchanged water, 265 parts of a 10% calcium phosphate suspension, 0.2 parts of sodium dodecylbenzenesulfonate, and styrene / acrylic resin fine particles having an average particle diameter of 0.20 μm are placed in a beaker and dissolved uniformly. did.

  While stirring this solution at a temperature of 60 ° C., the toner material solution (1) was added and stirred for 10 minutes. Here, in stirring, a TK homomixer was used, and the stirring condition was 12000 rpm.

  Next, 500 g of this mixed solution is weighed and transferred to a Kolben equipped with a stir bar and a thermometer, heated to 45 ° C., and the solvent is removed over 0.5 hour while performing a urea reaction under reduced pressure. After washing, drying, air classification. Thereby, a base particle can be obtained.

  Subsequently, 100 parts of the base particles and 0.25 part of the charge control agent were charged into a Q-type mixer (manufactured by Mitsui Mining Co., Ltd.), the peripheral speed of the turbine blades was set to 50 m / sec, and the operation was performed for 2 minutes, 1 minute. The rest was performed for 5 cycles, and the total processing time was 10 minutes. As the charge control agent, Bontron E-84 manufactured by Orient Chemical Co., Ltd. was used.

  Further, 0.5 part of hydrophobic silica (H2000, manufactured by Clariant Japan Co., Ltd.) was added, the peripheral speed was 15 m / sec, mixing was performed for 30 seconds and suspended for 1 minute for 5 cycles to obtain a cyan toner. Next, the toner of this embodiment can be obtained by mixing 100 parts of toner particles with 0.5 part of hydrophobic silica and 0.5 part of hydrophobic titanium oxide using a Henschel mixer.

  Further, yellow toner, magenta toner and black toner were produced in the same manner as described above. In the production of yellow toner, magenta toner, and black toner, each color toner was produced by substituting the following pigments for the copper phthalocyanine blue pigment (cyan pigment) used in the 4 parts of the cyan toner. .

Yellow toner: Benzine yellow pigment 6 parts Magenta toner: Rhodamine lake pigment 6 parts Black toner: Carbon black 10 parts By the way, the image forming apparatus according to the present embodiment is provided in a cartridge case which is detachable from the main body of the image forming apparatus. 7 is provided. The photosensitive drum 2 described above is held in the cartridge case 7 so as to be rotatable around the axis of the photosensitive drum 2. In the cartridge case 7, a charging roller 3, a developing device 4, and a cleaning device 8 to be described later are provided. Here, the process cartridge 9 is realized. In the image forming apparatus according to the present embodiment, the photosensitive drum 2, the charging roller 3, the developing device 4, and the cleaning device 8 are arranged in units of process cartridges 9 by detaching the cartridge case 7 from the image forming apparatus main body. Detachable.

  Thus, with respect to the photosensitive drum 2, the charging roller 3, the developing device 4, and the cleaning device 8, maintenance work and the like can be performed with the process cartridge 9 removed from the image forming apparatus main body. 2. Maintenance work can be facilitated when a failure or the like occurs in the charging roller 3, the developing device 4, or the cleaning device 8. In addition, by performing maintenance of the cleaning device 8 as appropriate, good cleaning performance can be maintained over a long period of time.

  In addition, a cleaning pad 3 a for removing foreign matters such as toner adhering to the charging roller 3 is provided in the cartridge case 7 of the present embodiment.

  In this embodiment, the process cartridge 9 that holds the photosensitive drum 2, the charging roller 3, the developing device 4, and the cleaning device 8 in the cartridge case 7 has been described. However, the present invention is not limited to this. Any cartridge may be used as long as it includes at least one of the charging roller 3, the developing device 4, and the cleaning device 8 and the photosensitive drum 2. In particular, in the present embodiment, a process cartridge 9 that is integrally provided with the cleaning device 8 and the photosensitive drum 2 and is detachably supported with respect to the image forming apparatus main body will be described.

  In addition, the process cartridge 9 of the present embodiment is provided around the photosensitive drum 2 and removes the charge on the surface of the photosensitive drum 2 after the toner image is transferred. An optical sensor 11 for controlling the density is provided.

  The transfer belt 5 applies a transfer voltage to the photosensitive drum 2 to transfer a toner image formed on the surface of the photosensitive drum 2 to a transfer sheet during an image forming operation described later. In the present embodiment, a transfer position is a position where the toner image formed on the surface of the photosensitive drum 2 is transferred to a transfer sheet (not shown) by the transfer belt 5.

  The printer engine 1 includes a registration roller 12 that adjusts the transfer timing of the transfer paper to the transfer position during an image forming operation to be described later.

  Next, the cleaning device 8 will be described. The printer engine 1 according to the present embodiment includes a cleaning device 8 that removes toner (residual toner) remaining on the surface of the photosensitive drum 2 after the transfer of the toner image by the transfer belt 5 from the surface of the photosensitive drum 2. As described above, the cleaning device 8 is held in the cartridge case 7, and can be attached to and detached from the image forming apparatus main body by attaching and detaching the cartridge case 7.

  The cleaning device 8 includes a cleaning blade 13 disposed so as to contact the surface of the photosensitive drum 2. The cleaning blade 13 has a flat plate shape, and one end side is supported by a blade holder 14. On the other end side of the cleaning blade 13, a contact portion 15 is provided in contact with the surface of the photosensitive drum 2 in parallel with the axis of the photosensitive member.

  The blade holder 14 brings the contact portion 15 of the cleaning blade 13 into contact with the photosensitive drum 2 from a direction (counter direction) that opposes the rotation direction of the photosensitive drum 2, and the cleaning blade 13 serves as the photosensitive drum. The cartridge case 7 is provided via a spring 16 so as to be swingable with respect to the surface of 2. In the image forming operation described later, when the photosensitive drum 2 rotates, the residual toner on the surface of the photosensitive drum 2 is scraped off from the surface of the photosensitive drum 2 by the cleaning blade 13.

  The cleaning blade 13 of the present embodiment is made of urethane rubber. The material forming the cleaning blade 13 is not limited to urethane rubber, and for example, rubber, metal, resin, or the like formed of a material other than urethane can be used.

  Here, FIG. 2 is an explanatory view showing the vicinity of the contact portion 15 in the cleaning blade 13 in an enlarged manner. The cleaning blade 13 is provided with a toner blocking surface 17 that forms a space S that expands from the contact portion 15 toward the upstream side in the rotation direction of the image carrier with the surface of the photosensitive drum 2. In the present embodiment, the toner blocking surface 17 extends from the contact portion 15 to the upstream side in the rotation direction of the photosensitive drum 2 so that the space S has an acute angle.

  As shown in FIG. 2, the toner blocking surface 17 is provided with a coating portion 18 as a high friction portion having a higher friction coefficient than the cleaning blade 13. The coating portion 18 is made of a material (high friction material) having a higher friction coefficient than the material forming the cleaning blade 13. Examples of such a high friction material include DLC (diamond-like carbon). The high friction material is not limited to DLC. The coating portion 18 is provided on the toner blocking surface 17 as long as it does not contact the surface of the photosensitive drum 2.

  The cleaning device 8 includes a toner collection blade 19 that collects residual toner scraped by the cleaning blade 13 and a toner collection coil 20 that conveys the residual toner collected by the toner collection blade 19 to a collection unit (not shown). .

  Although not particularly illustrated, the image forming apparatus includes a fixing unit provided downstream of the printer engine 1 in the transfer paper conveyance direction. The fixing unit applies heat and pressure to the transfer paper that has passed through the printer engine 1. As a result, the toner transferred onto the transfer paper by the transfer belt 5 is fused, and the toner image can be fixed on the transfer paper.

  In addition, as shown in FIG. 3, the image forming apparatus according to the present embodiment includes a PCU unit 21 that drives and controls each unit included in the image forming apparatus. For example, the PCU unit 21 drives and controls each unit included in the image forming apparatus when an image forming operation described below is executed. A PCU drive mechanism 22 is connected to the PCU unit 21. Drive of a main motor (not shown) provided in the image forming apparatus is transmitted to the PCU drive mechanism 22. The PCU unit 21 controls transmission of the driving force of the main motor to the PCU driving mechanism 22.

  The PCU unit 21 is connected to a photosensitive drum driving mechanism 23 that drives and controls the rotation of the photosensitive drum 2 and a charging mechanism 24 that drives and controls the operation of the charging roller 3. The photosensitive drum driving mechanism 23 and the charging mechanism 24 are driven and controlled by the PCU unit 21.

  Further, a cleaning mechanism 25, a toner recycling mechanism 23, and the like are connected to the PCU unit 21. The cleaning mechanism 25 drives and controls the toner collection blade 19 and the toner collection coil 20 in the cleaning device 8. The toner recycling mechanism 23 is driven and controlled by the PCU unit 21 to drive and control each unit (not shown) related to recycling of the toner collected by the cleaning device 8. Note that description of the recycling of the toner collected by the cleaning device 8 is omitted.

  In such an image forming operation in the printer engine 1, first, the photosensitive drum 2 is rotated counterclockwise in FIG. 1 and the surface of the photosensitive drum is neutralized by the neutralizing lamp 10. In the present embodiment, the surface potential of the photosensitive drum 2 is averaged to a reference potential of 0 to −150 V by this static elimination.

  Next, the surface of the photosensitive drum 2 is uniformly charged by the charging roller 3. In this embodiment, the surface potential of the photosensitive drum 2 is set to about −1000 V by this charging.

  Subsequently, the uniformly charged surface of the photosensitive drum 2 is exposed based on the image data by an exposure device (not shown). In the present embodiment, the surface potential of the portion that becomes the image portion by this exposure is set to 0 to −200V.

  In this state, when the toner on the developing sleeve 6 is supplied to the surface of the photosensitive drum 2 by the developing device 4, the toner adheres to the image portion and a toner image is formed on the surface of the photosensitive drum 2.

  The transfer belt 5 applies a transfer voltage when the toner image reaches the transfer position by the rotation of the photosensitive drum 2. At this time, the timing of the transfer paper conveyed to the transfer position is adjusted by the registration roller 12. As a result, the toner image on the surface of the photosensitive drum 2 is transferred to the transfer paper.

  The fixing unit applies heat and pressure to the transfer paper that has passed through the printer engine 1, thereby fusing the toner to the transfer paper and fixing the toner image transferred by the transfer belt 5 to the transfer paper. The transfer paper after the toner image is fixed is discharged to a paper discharge section.

  By the way, in the image forming operation, the toner may remain on the surface of the photosensitive drum 2 without being completely transferred onto the transfer paper. In the present embodiment, the toner remaining on the surface of the photosensitive drum 2 after passing through the transfer process by the transfer belt will be described as a residual toner hereinafter. Residual toner on the surface of the photosensitive drum 2 is electrostatically attached to the photosensitive drum 2.

  As the photosensitive drum 2 rotates, the cleaning device 8 scrapes the residual toner on the surface of the photosensitive drum 2 with the cleaning blade 13 and rotates the toner recovery blade 19 to recover the scraped residual toner. . The residual toner collected by the toner collection blade 19 is conveyed by a toner collection coil 20 to a collection unit (not shown).

  Here, FIG. 4 is a schematic diagram for explaining the behavior of the remaining toner during the image forming operation. As can be seen from FIG. 4, since the contact portion 15 of the cleaning blade 13 is in contact with the surface of the photosensitive drum 2, when the photosensitive drum 2 rotates during the image forming operation, the residual toner ta on the surface of the photosensitive drum 2 is increased. As the photosensitive drum 2 rotates, it moves from right to left in FIG. The force is F1 obtained by multiplying N1 obtained by combining the vertical drag generated by the electrostatic force and the vertical drag generated by the weight of the residual toner ta by the friction coefficient μ1 of the image carrier.

  When the residual toner ta is moved by the rotation of the photosensitive drum 2 and hits the toner blocking surface 17 of the cleaning blade 13, the residual toner ta is transferred to the photosensitive drum by the toner blocking surface 17 of the cleaning blade 13. The force which pushes back to the upstream of 2 rotation direction acts. This force is Fb. Further, the residual toner ta is pressed with a force of Ft from the rear side in the advancing direction by the toner tb positioned on the upstream side in the rotation direction of the photosensitive drum 2 with respect to the residual toner ta.

  Here, if the residual toner ta moved by the rotation of the photosensitive drum 2 is pushed back by the cleaning blade 13, the residual toner ta on the surface of the photosensitive drum 2 can be cleaned by stopping at the position shown in FIG. become.

  As the photosensitive drum 2 rotates, the remaining toner ta in contact with the toner blocking surface 17 of the cleaning blade 13 and being pushed back by the toner blocking surface 17 includes three toners indicated by F1, F3, and Ft. Power is acting. The residual toner ta is likely to rotate on the surface of the photosensitive drum 2 or difficult to rotate in accordance with the resultant force of these three forces F1, F3, and Ft. The force F1 is represented by the product of the friction coefficient μ1 on the surface of the photosensitive drum 2 and the force N1 applied to the photosensitive drum 2 by the residual toner ta. The force F3 is expressed by the product of the friction coefficient μ3 of the toner blocking surface 17 of the cleaning blade 13 and the force Fb. The force Ft is a force acting at the contact point of the residual toner ta and tb according to the force Nt applied by the residual toner tb to the residual toner ta and the frictional force μt between the residual toners ta and tb.

  The residual toner ta rotates, for example, in the clockwise direction in FIG. 4 when μ1 is very high, and slips between the remaining toner ta and the surface of the photosensitive drum 2 when μ1 is very low and close to 0, The photosensitive drum 2 slides toward the upstream side in the rotation direction. Further, the residual toner ta rotates while sliding with the toner blocking surface 17 of the cleaning blade 13 when μ3 is 0, but is stopped when μ3 is very high.

  By the way, when the residual toner ta that is pressed against the toner blocking surface 17 rotates, the residual toner ta is formed between the outer peripheral surface of the photosensitive drum 2 and the toner blocking surface 17 of the cleaning blade 13. It enters the space S (see FIG. 2). As a result, a force for pressing the residual toner ta toward the surface of the photosensitive drum 2 is applied to the residual toner ta by the cleaning blade 13. N1 increases with this. As a result, F1 increases, and finally the cleaning blade 13 is pushed up by the rolling force of the remaining toner ta, and the contact portion 15 is separated from the surface of the photosensitive drum 2. When a gap is generated between the cleaning blade 13 and the surface of the photosensitive drum 2 as described above, the toner enters the gap, and the residual toner ta slips between the cleaning blade 13 and the surface of the photosensitive drum 2. A slip occurs. When such slip-through occurs, in the subsequent image forming operation, the toner that has not been completely cleaned adversely affects the image quality.

  Such a problem can be dealt with, for example, by reducing μ1 (see, for example, Patent Document 2). However, in order to manufacture the photosensitive drum 2 having appropriate performance, not only the friction coefficient μ1 of the surface of the photosensitive drum 2 but also various other performances must be managed. For this reason, depending on the material for manufacturing the photosensitive drum 2, it may be difficult to properly maintain the friction coefficient μ1 on the surface of the photosensitive drum 2. On the contrary, it is not preferable to lower the performance of the photosensitive drum 2 itself in order to ensure the friction coefficient μ1 on the surface of the photosensitive drum 2.

  As described above, when μ1 cannot be lowered sufficiently, it is possible to reduce the rotation of the toner by increasing the friction coefficient μ3 of the toner blocking surface 17 and to make it difficult to cause the cleaning failure. However, when the friction coefficient μ3 of the cleaning blade 13 that is normally used is increased, the cleaning performance may be deteriorated. For example, when the friction coefficient μ3 of the entire cleaning blade 13 is excessively increased, the friction between the surface of the photosensitive drum 2 and the cleaning blade 13 is increased and the surface property of the photosensitive drum 2 is lowered, and residual toner is generated. It may be that it promotes.

  On the other hand, in the present embodiment, the toner blocking surface 17 is provided on the toner blocking surface 17 by increasing the friction coefficient by providing the coating portion 18 on the toner blocking surface 17 that is in contact with the residual toner ta and is not used for cleaning. Even when the photosensitive drum 2 rotates with the remaining toner ta in contact, the rotation of the remaining toner a can be suppressed. As a result, it is possible to reduce the occurrence of defective cleaning due to the residual toners ta and tb slipping through between the cleaning blade 13 and the surface of the photosensitive drum 2.

  The coating portion 18 is not limited to the entire toner blocking surface 17, and may be provided, for example, on a part of the toner blocking surface 17. Also at this time, the coating portion 18 is provided in a range where the toner blocking surface 17 does not contact the surface of the photosensitive drum 2.

  As a result, a good image can be formed using the photosensitive drum 2 from which the residual toner ta has been removed in the subsequent image forming operation.

  By the way, in the present embodiment, as described above, the toner manufactured using the polymerization method is used. Since the toner produced using the polymerization method can have a small particle size and uniform particle size, the image is very clean. However, it is generally considered that cleaning is very difficult because the toner shape is spherical.

  On the other hand, in this embodiment, since the cleaning blade 13 provided with the coating portion 18 as described above is used, the residual toner ta can be reliably removed and the cleaning performance can be improved.

Here, the optimum setting condition for toner removal in the cleaning blade 13 needs to be very severe. As an optimum setting condition for toner removal in the cleaning blade 13, for example, in the image forming apparatus of the present embodiment, the contact pressure of the cleaning blade 13 is 35.1 gf / cm ^2, and the cleaning blade 13 is in contact with the surface of the photosensitive drum 2. Each contact is preferably set to 20 degrees. At this time, the angle formed by the toner blocking surface 17 and the surface of the photosensitive drum 2 is set to 70 degrees. The friction coefficient μ1 on the surface of the photosensitive drum 2 is appropriately set according to the cleaning performance required in the actual image forming apparatus. As one of the methods, for example, the residual toner from the cleaning blade 13 when the various conditions relating to the cleaning of the residual toner ta such as the friction coefficient μ1 of the surface of the photosensitive drum 2 and the cleaning blade 13 are varied. And a method of setting an optimum value based on the amount of leakage.

  Next, a second embodiment for carrying out the present invention will be described with reference to FIG. Note that the same parts as those of the above-described embodiment are denoted by the same reference numerals, and description thereof is also omitted. The same shall apply hereinafter.

  FIG. 5 is an explanatory view showing, in an enlarged manner, the vicinity of the contact portion 15 in the cleaning blade 13 provided in the image forming apparatus according to the second embodiment for carrying out the present invention. As shown in FIG. 5, in the cleaning blade 13 of the present embodiment, the surface roughness of the toner blocking surface 17 is set to be rougher than the surface roughness of portions other than the toner blocking surface 17 of the cleaning blade 13. In the present embodiment, the high friction portion is realized by setting the surface roughness of the toner blocking surface 17 to be larger than the surface roughness of the portion other than the toner blocking surface 17 in the cleaning blade 13.

  In such a cleaning device 8, during the image forming operation, the residual toner ta comes into contact with the toner blocking surface 17 at a plurality of points. As a result, the contact area between the remaining toner ta and the toner blocking surface 17 is increased, and the remaining toner ta can be prevented from rolling. As a result, it is possible to prevent the residual toner ta from slipping between the cleaning blade 13 and the photosensitive drum 2, thereby suppressing the occurrence of defective cleaning.

1 is a schematic diagram showing a printer engine in an image forming apparatus according to a first embodiment for carrying out the present invention. It is explanatory drawing which expands and shows the contact part vicinity in a cleaning blade. FIG. 2 is a block diagram schematically illustrating electrical connection of each unit included in the image forming apparatus. FIG. 6 is a schematic diagram illustrating the behavior of residual toner during an image forming operation. It is explanatory drawing which expands and shows the contact part vicinity in the cleaning blade with which the image forming apparatus of 2nd Embodiment for implementing this invention is provided.

Explanation of symbols

2 Image carrier 8 Cleaning device 9 Process cartridge 13 Cleaning blade 15 Contact portion 17 Toner blocking surface 18 High friction portion S space

Claims (7)

A toner blocking surface that forms a space expanding from the contact portion toward the upstream side in the moving direction of the image carrier between the contact portion that contacts the outer peripheral surface of the image carrier and the outer peripheral surface of the image carrier. And a cleaning blade having
The coefficient of friction is greater than that of the material forming the cleaning blade so as to suppress the movement of the toner in contact with the toner blocking surface with respect to the outer peripheral surface of the image bearing member provided on the toner blocking surface. High friction part,
A cleaning device comprising:   The cleaning device according to claim 1, wherein the high friction portion is provided by coating the toner blocking surface with a high friction material having a higher friction coefficient than a material forming the cleaning blade.   The cleaning device according to claim 1, wherein the high friction portion is provided by roughening a surface property of the toner blocking surface.   4. A process cartridge comprising the cleaning device according to claim 1, 2 or 3 and an image carrier integrally, and detachably supported on the image forming apparatus main body.   An image forming apparatus comprising the process cartridge according to claim 4.   An image forming apparatus comprising the cleaning device according to claim 1. 7. The toner according to claim 5, wherein the toner is formed by a polyaddition reaction of a toner composition comprising a release agent dispersed in an aqueous medium in which a prepolymer, a colorant, and resin fine particles are present. Image forming apparatus.

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