JP2012133001A - Cleaning device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning device that maintains cleaning capability for a long period and prevents image failure due to a decrease in cleaning capability.SOLUTION: A cleaning device 20 comes into contact with the surface of a charging roller 2 to remove attached substances attached to the surface. The cleaning device 20 includes a collection layer that comes into contact with the surface of the charging roller 2 to collect attached substances attached to the surface. The cleaning device 20 further has a cleaning roller 21 that comes into contact with the surface of the charging roller 2 while rotating to remove the attached substances, and a polishing roller 22 that comes into contact with the collection layer of the cleaning roller 21 to polish the collection layer.

Description

  The present invention relates to a cleaning device that contacts a surface of an image carrier or a surface of a charging roller that charges the surface of the image carrier, and removes deposits attached to the surface, and an image forming apparatus including the cleaning device.

  Conventionally, in an electrophotographic image forming apparatus, the following configuration is known as a cleaning device that removes deposits such as toner and paper dust attached to the surface of a photosensitive drum as an image carrier and a charging roller. ing.

  Specifically, as disclosed in Patent Document 1, a sponge member (elastic member) as a cleaning member is used, and this is brought into contact with the surface of the charging roller, and the outer peripheral surface thereof is rubbed and adhered. The structure which cleans is known.

  Since the sponge material is porous, deposits adhering to the surfaces of the photosensitive drum and the charging roller can be collected in the holes of the sponge material. Further, since the sponge material is elastic and easily deforms in accordance with the shape of the surface of the photosensitive drum or the charging roller, it is possible to reliably remove the deposits without requiring any mounting accuracy. In addition, the sponge material is compressed against the elasticity by pressing with the charging roller, so that it can reliably rub against the unevenness and eccentricity of the charging roller and effectively remove the deposits. it can. As the sponge material, for example, foamed polyurethane or foamed polyethylene is used.

JP 05-297690 A

  However, according to the prior art, the ability of the sponge material (elastic member) to collect deposits in the holes of the sponge material is reduced when the charging roller rotates and is repeatedly used. That is, the ability to collect deposits over a long period (cleaning ability) cannot be maintained. The adhering material such as toner and paper dust accumulates on the charging roller corresponding to the portion where the sponge material collecting ability (cleaning ability) is reduced, and the charging failure when charging the photosensitive drum is reduced. This causes density unevenness and streaky image defects.

  An object of the present invention is to provide a cleaning device that can maintain a cleaning capability for a long period of time and can prevent image defects due to a decrease in the cleaning capability.

  In order to achieve the above object, the present invention provides a cleaning device that removes deposits attached to the surface by contacting the surface of the image carrier or the surface of a charging roller that charges the surface of the image carrier. A cleaning member that contacts the surface of the image carrier or the charging roller and collects the adhered matter that adheres to the surface, and that removes the adhered matter while rotating in contact with the surface; And a polishing member that contacts the collection layer of the cleaning member and polishes the collection layer.

  According to the present invention, by polishing the collection layer of the cleaning member with the polishing member, scraping off the surface layer having a reduced ability to collect deposits, taking out a new surface layer having the original collection ability, The cleaning ability can be restored. As a result, a stable cleaning ability can be maintained over a long period of time, and image defects due to a reduction in cleaning ability can be prevented.

Schematic diagram of a main part showing a schematic configuration of an image forming apparatus having a cleaning device Schematic diagram of charging roller (A), (b) is sectional drawing which shows an example of the manufacturing apparatus of a cleaning roller, (c) is a perspective view of a cleaning roller. (A) is a schematic cross-sectional view showing an example of a charging roller cleaning device, and (b) is a perspective view of a polishing roller. Schematic diagram showing the support structure of the polishing roller Block diagram showing the configuration of a control unit for controlling the operation of the polishing roller Flow chart showing the flow of polishing operation control Table showing the coefficient table for determining the polishing time by the polishing roller The table which shows the result which compared the polishing power and cleaning ability of execution example and comparative example

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the following embodiments should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions. Therefore, unless specifically stated otherwise, the scope of the present invention is not intended to be limited thereto.

[Image forming apparatus]
First, an image forming apparatus including the cleaning device according to the present embodiment will be described. FIG. 1 is a schematic diagram illustrating a schematic configuration of an image forming apparatus.

  This image forming apparatus has a photosensitive drum 1 as an image carrier for carrying an image. The photosensitive drum 1 is provided so as to be rotatable about an axis, and is driven to rotate at a predetermined speed in the arrow direction (clockwise direction) in FIG. 1 by a drive mechanism (not shown).

  The surface of the rotating photosensitive drum 1 is uniformly charged to a predetermined polarity and potential by charging means. In this example, the charging means is a contact charging device (roller charging device) using a charging roller 2 as a charging member. The charging roller 2 is a conductive elastic roller having a roller shaft (conductive support, cored bar). Then, both end portions of the roller shaft body are rotatably supported via bearing members, and the roller axis is arranged substantially parallel to the axis of the photoconductive drum 1 so that a predetermined pressing force is applied to the photoconductive drum 1. Are disposed in contact with each other. In this example, the charging roller 2 rotates following the rotation of the photosensitive drum 1. Further, the charging roller 2 has surface irregularities formed by mixing resin particles in the surface layer. The charging roller 2 will be described later.

  The surface of the charging roller 2 is cleaned by a cleaning (urethane sponge roller) 21 as a cleaning member that constitutes a cleaning device. The cleaning roller 21 contacts the surface of the charging roller 2 and collects the adhering matter (foreign matter) adhering to the surface, thereby preventing the surface of the charging roller 2 from being locally or entirely contaminated with the adhering matter. . This cleaning roller 21 rotates following the charging roller 2. The cleaning roller 21 will also be described later.

  The surface layer of the cleaning roller 21 as a cleaning member is polished by a polishing roller 22 as a polishing member constituting a cleaning device. By using the polishing roller, it is possible to scrape the surface layer having a reduced ability to collect deposits, to produce a new surface layer having the original collecting ability, and to recover the cleaning ability. As a result, a stable cleaning ability can be maintained over a long period of time, and image defects due to a reduction in cleaning ability can be prevented. The polishing roller 22 will also be described later.

  A predetermined DC voltage (DC charging method) or a voltage obtained by superimposing a predetermined AC voltage on the predetermined DC voltage (AC + DC charging method) is applied to the roller shaft body of the charging roller 2 from the charging bias application power source P1. Applied as a charging bias. As a result, the surface of the rotating photosensitive drum 1 is uniformly contact-charged to a predetermined polarity / potential. In this example, the surface of the photosensitive drum 1 is charged to a predetermined negative potential.

  Then, the image exposure means 3 performs image exposure on the charged surface of the photosensitive drum 1. As a result, the exposed bright portion on the surface of the photosensitive drum 1 is attenuated, and an electrostatic latent image corresponding to the image exposure pattern is formed on the drum surface. The image exposure means 3 may be an analog exposure device that performs image projection exposure of a document image, or may be a digital exposure device such as a laser scanner or an LED array. In this example, a laser scanner that performs laser scanning exposure L with a wavelength λ = 780 nm is used as the image exposure means 3.

  The electrostatic latent image formed on the surface of the photosensitive drum as described above is developed as a toner image by the developing means. In this example, the developing means uses a jumping reversal developing device 4 using a one-component magnetic negative polarity toner as a developer. However, the development method is not limited to this, and other development methods may be used. For example, a method (two-component contact development) in which toner particles mixed with a magnetic carrier are used as a developer, and the developer is conveyed by magnetic force and developed in contact with the image carrier. Further, a method of developing the two-component developer in a non-contact state with respect to the image carrier (two-component non-contact development method) can also be suitably used.

  The developing device 4 has a developing sleeve 5 that is rotationally driven, and a hopper portion 6 for supplying a developer to the developing sleeve 5, and a constant interval is provided between the developing sleeve 5 and the photosensitive drum 1 over the length of the device. (Here, 0.3 mm) is maintained. A voltage obtained by superimposing a predetermined AC component and a DC component is applied to the developing sleeve 5 from the developing bias applying power supply unit P2. As a result, the electrostatic latent image on the surface of the photosensitive drum is jumped and reversed (developed) by the developer from the developing device 4.

  The toner image formed on the surface of the photosensitive drum 1 reaches the transfer portion T which is a contact nip portion between the photosensitive drum 1 and the transfer roller 7 by the subsequent rotation of the photosensitive drum 1. The recording material (transfer target) S is transferred to the fed recording material. The transfer roller 7 is a conductive elastic roller having a roller shaft (conductive support, cored bar). The transfer roller 7 is supported such that both ends of the roller shaft body are rotatable via bearing members, and the roller axis is arranged substantially in parallel with the axis of the photoconductive drum 1 with respect to the photoconductive drum 1. Are arranged in contact with each other with a predetermined pressing force. In this example, the transfer roller 7 rotates following the rotation of the photosensitive drum 1.

  The recording material S is fed from a feeding unit (not shown) at a predetermined control timing, is synchronized with the image formation on the photosensitive drum 1 by the registration roller 8, and is introduced into the transfer unit T at an appropriate timing. It is nipped and conveyed by the body drum 1 and the transfer roller 7. While the recording material S passes through the transfer portion T, a DC voltage having a predetermined potential opposite to the charging polarity of the toner is applied to the transfer roller 7 from the transfer portion T. In this example, a positive polarity DC voltage having a predetermined potential is applied. As a result, a positive charge is applied to the back side of the recording material S (the surface on the transfer roller 7 side) in the transfer portion T, and the toner image on the surface of the photosensitive drum 1 is sequentially transferred to the surface of the recording material S. It is transferred electronically.

  When the recording material S having received the transfer of the toner image exits the transfer portion T, it is separated from the surface of the photosensitive drum 1 and introduced into the fixing device 11 by the transport belt 10. The fixing device 11 of this example is a heat fixing device having a pressure rotating roller pair of a fixing roller (heat roller) 12 having a heat source and a pressure roller 13, and the recording material S introduced into the fixing device 11 is a roller pair. The toner enters the fixing portion N, which is the pressure nip portion 12 and 13, and is nipped and conveyed. As a result, the unfixed toner image on the recording material S is fixed as a fixed image on the surface of the recording material by heat and pressure, and then the recording material is discharged outside the apparatus body as an image formed product.

  On the other hand, the surface of the photosensitive drum 1 after separation of the recording material is cleaned by removing the residual toner such as transfer residual toner and paper dust by a cleaning device 14 as a cleaning unit, and repeatedly used for image formation. . In this example, the cleaning device 14 is a blade cleaning device using a cleaning blade 15 as a cleaning member. The cleaning blade 15 rubs the surface of the photosensitive drum 1 to scrape residues from the surface of the photosensitive drum. The scraped residue is stored in the collected toner storage unit 16.

  Next, the charging roller 2 and the cleaning roller 21 and the polishing roller 22 constituting the cleaning device 20 that removes deposits attached to the surface of the charging roller 2 will be described in detail.

[Charging roller]
An example of the charging roller will be described with reference to FIG. As shown in FIG. 2, the charging roller 2 includes a shaft body 201, a conductive elastic body layer 202 formed on the outer periphery thereof, a softener migration preventing layer 203 on the outer periphery thereof, and a resistance formed on the outer periphery thereof. An adjustment layer (or dielectric layer) 204 and a protective layer 205 are included.

[Cleaning roller]
An example of a cleaning roller as a cleaning member will be described with reference to FIGS. 3 (a), 3 (b), and 3 (c). Here, a urethane sponge roller is illustrated as the cleaning roller, but the cleaning roller as the cleaning member is not limited to this.

  The cleaning roller 21 as a cleaning member has a collection layer for collecting deposits on the surface as a surface layer in contact with the surface of the charging roller. Specifically, as shown in FIG. 3C, the cleaning roller 21 as a cleaning member has an elastic body layer 21b made of a rubber material or a resin material on the outer periphery of the shaft 21a as the collection layer. Yes. In particular, a roller having a foam layer, in which the elastic layer is formed of a foam (such as a porous sponge member) made of a polymer elastic foam having a low hardness, is used. In a roller having such a foam layer, the foam layer has a uniform cell structure over the entire roller, and thus a uniform hardness according to the application is realized.

  As a method for manufacturing such a roller, a method in which a foam layer is formed by integral molding with a shaft using a mold in which a shaft is previously disposed is generally used. Methods have been reviewed and proposed. An example of a mold that can be used in such a manufacturing method is shown in FIG.

  A mold 40 shown in FIGS. 3A and 3B includes a hollow columnar mold body 41 and caps 42a and 42b that are inserted through both ends of the mold body 41 and hold a core metal 43 as a shaft 21a. The roller is manufactured by injecting the raw material into the core body 43 with the core metal 43 penetrating the center line of the mold body 41. In manufacturing a roller using this mold 40, as shown in FIG. 3B, a predetermined amount of raw material 45 is injected from the hole 44a of the upper cap 42a and filled therein. Reference numeral 46 in the figure denotes an injection head of the injection machine. In this case, as the raw material 45 is filled up to the lower end inside the mold 40, the air 47 escapes from the hole 44b of the lower cap 42b.

  As a material of the mold body 41, ceramics can be used in addition to metals such as iron, copper, aluminum, and stainless steel. Moreover, as the metal core (shaft) 43, for example, a metal member obtained by plating zinc or the like on a steel material such as sulfur free-cutting steel, or various metal members such as aluminum, stainless steel, or magnesium alloy can be used. .

  As described above, the cleaning roller 21 includes a shaft 21a and an elastic body layer 21b made of polyurethane foam formed on the outer periphery of the shaft 21a (see FIG. 3C). The elastic layer 21b of the cleaning roller 21 is formed by the roller manufacturing method described above. An appropriate diameter of this cleaning roller (urethane sponge roller) is about φ6 to φ20. When the diameter of the cleaning roller is smaller than the above-mentioned value, the strength and cleaning ability as the cleaning roller cannot be ensured. It is not preferable in terms of space.

  Based on the above, an example of the thickness of the elastic layer 21b of the cleaning roller 21 and a shaft (shaft) 21a will be described. In order to ensure the cleaning ability, the elastic layer 21b needs to have a thickness of a predetermined value or more (here, 2 mm or more). Therefore, the diameter of the shaft 21a is suitably about φ4 to φ16. When the diameter of the shaft 21a is smaller than the above-mentioned value, the roller strength is reduced, and a problem such as inability to uniformly contact the charging roller occurs due to deformation or the like. On the other hand, if the diameter of the shaft 21a is larger than the above value, the thickness of the elastic layer 21b cannot be ensured, which may lead to poor cleaning. The roller having the elastic layer can be used as a developing roller, a charging roller, a toner conveying roller, a transfer roller, a feeding roller, a cleaning roller, a fixing pressure roller, and the like of the image forming apparatus. Suitable as a transfer roller and a cleaning roller.

  Further, the shaft (shaft) 21a of the cleaning roller 21 is not particularly limited as long as it has good conductivity. For example, a metal core made of a solid metal such as iron, stainless steel, or aluminum, a metal shaft such as a metal cylinder hollowed inside, or a shaft made of a highly conductive plastic may be used. it can.

  The cleaning roller 21 may be manufactured by the above-described manufacturing method, and materials for the core metal and the foam layer (elastic body layer) are appropriately selected from those used for conventional roller members. It may be used and is not particularly limited. By performing integral molding by the above manufacturing method, there can be no problem such as voids, and a roller member having a homogeneous structure as a whole can be obtained.

[Polishing roller and polishing apparatus]
Next, a polishing roller as a polishing member and a polishing apparatus as the cleaning device 20 will be described with reference to FIGS. 4 (a) and 4 (b). Here, an example of a polishing apparatus is simplified and shown in FIG. FIG. 4A is a schematic cross-sectional view illustrating a charging roller and a cleaning device for the charging roller in the image forming apparatus. Note that the polishing roller and the polishing apparatus described here are merely examples, and the present invention is not limited thereto.

  Generally, as a conventional processing method, a method of grinding or polishing with a polishing means such as a grindstone while rotating the outer peripheral surface of a roller is used.

  First, an example of the polishing roller 22 as a polishing member is shown below. The layer structure of the polishing roller includes a shaft 22a and a polishing layer 22b made of a polishing grindstone formed on the outer periphery of the shaft 22a (see FIG. 4B). The polishing layer 22b is formed by an abrasive manufacturing method described later. An appropriate diameter of the polishing roller 22 is about φ6 to φ30. When the diameter of the polishing roller 22 is smaller than the aforementioned value (φ6), the strength and cleaning ability as the cleaning roller cannot be secured, and when larger than the aforementioned value (φ30), there is no problem with the cleaning ability, but the size. Becomes large, which is not preferable in terms of space saving.

  Further, in order to ensure the polishing ability, the thickness of the polishing layer 22b is required to be a predetermined thickness (here, 1 mm or more). Therefore, the diameter of the shaft 21a is suitably about φ4 to φ28. When the diameter of the shaft is smaller than the above-mentioned value (φ4), the roller strength is reduced, and deformation or the like occurs, resulting in problems such as being unable to contact the urethane sponge roller as a cleaning member uniformly. On the other hand, when the diameter of the shaft is larger than the aforementioned value (φ28), the thickness of the polishing layer 22b cannot be ensured, which may lead to poor cleaning due to poor polishing of the urethane sponge roller.

  As an indicator of the surface state of the polishing roller, there is an index called grain size. The particle size (grain size) is a unit that expresses the size of what is called an abrasive that is attached to the polishing surface and corresponds to a blade for cutting a workpiece, and is standardized as a JIS general abrasive particle size. For example, when the particle size of the polishing roller is # 100, the average particle size of the abrasive grains is 149 μm, and when the particle size of the polishing roller is # 1000, the average particle size of the abrasive particles is 15 μm, so that the larger the particle size, the larger the abrasive particles The average particle size of becomes small. In general, abrasive grains having a particle size of # 8 to # 220 are called coarse particles, and are suitable for polishing and grinding of a urethane sponge roller or the like to be polished this time, and those having a particle size of # 220 or more are fine particles. It is called and is suitable for finishing such as mirror finishing of metal surfaces. The surface condition of the polishing roller is preferably that having a particle size of # 20 to 220. When the particle size is # 20 or less, the degree of polishing of the urethane sponge roller is high, and when the particle size is # 220 or more, the degree of polishing of the urethane sponge roller is low, resulting in an image defect due to poor cleaning.

  Another index indicating the surface state of the polishing roller is a volume ratio of abrasive grains in a grindstone called a structure called a structure (structure). The structure is said to be dense if the proportion of abrasive grains in a certain volume is large, and coarse if it is small. For example, when the structure of the polishing roller is 0, the abrasive grain ratio is 62%, and when the structure is 14, the abrasive grain ratio is 34%. Generally, a polishing roller (grinding stone) having a structure of 0 to 7 is a hard and brittle material and is suitable for precision finishing. A polishing roller (grinding stone) having a structure of 8 or more becomes a soft and sticky material and is suitable for ordinary finishing. The surface condition of the polishing roller is preferably 8 or more. In the case of a structure of 7 or less, the polishing degree of the urethane sponge roller becomes low, and an image defect due to poor cleaning occurs.

  According to this example, in the surface finishing treatment of a urethane sponge or metal surface by polishing, a polishing material that can form a good smooth surface and has an effect of excellent durability of the polishing material, and a method for manufacturing the same are provided. can do. In particular, the glass transition temperature is 25 ° C. or less, the acrylic resin is adopted, and the abrasive particles are dispersed in a substantially spherical shape and subjected to hydrophobic treatment, thereby improving both the polishing ability and durability of the abrasive. Excellent. In addition, since the abrasive can be produced by suspension polymerization, a uniform abrasive having a uniform particle diameter can be easily produced.

  The abrasive according to the present example has a substantially spherical shape in which abrasive grains are dispersed in an acrylic resin matrix. By using an acrylic resin as a matrix, there is an effect that the durability of the abrasive is excellent. The acrylic resin is not particularly limited as long as it is obtained by polymerizing an acrylic monomer.

  Examples of the monomer include acrylic acid ester or methacrylic acid ester, alkoxy polyalkylene glycol acrylate or alkoxy polyalkylene glycol (meth) acrylate, acrylic acid or methacrylic acid, and acrylic acid ester monomer or methacrylic acid ester. Monomers include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, acrylic acid alkyl esters such as 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate. Methacrylic acid alkyl esters such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate-containing (meth) acrylic acid esters such as methoxypolyethylene glycol Acrylate, alkoxy polyalkylene glycol (meth) acrylates such as methoxy polyethylene glycol methacrylate, acrylic acid, and methacrylic acid. These can be used alone or in combination of two or more.

  Other monomers can be used in combination with the acrylic monomer. These monomers include aromatic vinyl monomers such as styrene, α-methylstyrene, p-methylstyrene, p-tert-butylstyrene, chlorostyrene, bromostyrene, etc. Acrylonitrile, methacrylonitrile and the like can be used in combination.

  When another monomer is used in combination, an acrylic monomer is used as a main component, and the glass transition temperature is 25 ° C. or lower.

  Among these, acrylic acid alkyl ester is preferable in that a good mirror surface can be formed. Of these, ethyl acrylate and butyl acrylate are more preferable because of their high effects.

  Moreover, it is preferable to crosslink acrylic resin, and as a crosslinking method, a monomer having two or more vinyl groups in the molecule can be used. Examples of such crosslinkers include ethylene glycol diacrylate, 1,3-butanediol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate. Polyacrylates such as acrylate, polyethylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, acrylic modified polydimethylsiloxane, ethylene glycol Dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate 1,6-hexanediol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol hexa Examples thereof include polymethacrylic acid esters such as methacrylate and methacryl-modified polydimethylsiloxane, and aromatic vinyl compounds such as divinylbenzene. These can be used alone or in combination of two or more.

  The amount used is preferably 0.01 to 50 parts by weight, more preferably 0.1 to 30 parts by weight, and still more preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the total amount of monomers. If the amount exceeds 50 parts by weight, the density of the cross-linking points increases and the resin tends to be brittle and inferior in durability. If it is less than 0.01 parts by weight, the cross-link density is insufficient and the mechanical strength is lowered, which is also durable. Tend to be inferior.

  The acrylic resin needs to have a glass transition temperature of 25 ° C. or lower, and more preferably 0 ° C. or lower. When the glass transition temperature exceeds 25 ° C., the elastic force is low and brittle, so that the durability as an abrasive is inferior. Although there is no restriction | limiting in particular in a lower limit, Generally a -80 degreeC or more thing is used. The glass transition temperature can be measured by a differential scanning calorimetry (DSC method).

  There is no restriction | limiting in particular as an abrasive grain to be used, Silicon carbide, silica, silicon nitride, titanium oxide, alundum, white alundum, corundum, green corundum, alumina, zirconia, hexagonal boron nitride, diamond, ceria, titania, Hard inorganic fine particles such as zirconia and manganese oxide can be used.

  The average particle diameter of these abrasive grains is preferably from 0.1 to 400 μm, more preferably from 0.4 to 300 μm. When the average particle size is less than 0.1 μm, the particles are too small to be produced, and the durability tends to be inferior. On the other hand, when the average particle size exceeds 400 μm, the polishing effect tends to be inferior. The average particle diameter can be measured by a laser scattering diffraction method.

  Moreover, there is no restriction | limiting in particular as content of the abrasive grain in an abrasive | polishing material, However, 5 to 80 weight% is preferable with respect to an acrylic resin matrix and an abrasive grain, and 10 to 60 weight% is more preferable. If the content is less than 5% by weight, the polishing property tends to be inferior, whereas if it exceeds 80% by weight, the durability tends to be inferior.

  The abrasive particles in this example are substantially spherical. The substantially spherical shape is a smooth appearance shape that is a perfect sphere or close to a true sphere. The case where sharp abrasive grains partially protrude from the surface is also included. Thus, since it is a substantially spherical shape, since the lubricity and fluidity of the abrasive particles are improved, the clogging of the abrasive during blasting is eliminated, and the workability can be improved.

  The average particle diameter of the abrasive is preferably 0.001 to 2 mm, and more preferably 0.01 to 2 mm. If this value is less than 0.001 mm, the particles are too small to be difficult to produce, and the polishing effect tends to be inferior. On the other hand, those exceeding 2 mm are still difficult to manufacture.

  Next, a method for producing the above abrasive will be described.

  As a method for producing the above abrasive, a method in which an acrylic monomer is subjected to suspension polymerization in the presence of abrasive grains can be mentioned as a preferred method.

  According to this method, a substantially spherical abrasive can be produced efficiently and with a relatively uniform particle size. In this method, generally, polymerization is carried out by dispersing an acrylic monomer in which a catalyst such as an organic peroxide is dissolved in an aqueous medium containing a dispersant to generate radicals.

  As the dispersant, a sparingly soluble inorganic salt may be used, or this may be used in combination with a surfactant, and conventionally known organic dispersants such as PVA can also be used. As the hardly soluble inorganic salt, magnesium phosphate, tricalcium phosphate or the like can be used. As the surfactant, any of sodium oleate, sodium dodecylbenzenesulfonate, and other anionic surfactants and nonionic surfactants generally used for suspension polymerization can be used. As the organic dispersant, polyvinyl alcohol, polyvinyl pyrrolidone, methyl cellulose and the like can be used.

  A conventionally well-known thing can be used for an organic peroxide. For example, there are lauroyl peroxide, benzoyl peroxide, t-butyl peroxybenzoate, t-butyl peroxyisopropyl carbonate, and the like. The organic peroxide is preferably used in an amount of 0.001 to 1.0% by weight based on the polymerizable monomer. One or more organic peroxides can be used.

  The abrasive is particularly preferably obtained by dispersing the abrasive grains in an acrylic monomer, adding this to an aqueous medium, dispersing oil droplets in the aqueous medium, and suspension polymerization.

  Here, it is preferable that the abrasive grains have been subjected to a hydrophobic treatment in advance because an abrasive having a good structure and high strength can be produced. Examples of hydrophobic treatment agents include stearic acid, silane compounds, petrolatum and the like. As a treatment method using a hydrophobic treating agent, a wet method, a dry method, or the like can be used.

  Hereinafter, the cleaning device 20 having the cleaning roller 21 and the polishing roller 22 described above will be described in more detail with reference to the drawings. FIG. 4A is a schematic plan view showing an example of the cleaning device. Here, 21 is a cleaning roller (urethane sponge roller), 22 is a polishing roller (abrasive member), 31 is a polishing scrap collecting blade on the surface of the cleaning roller, and 32 is a polishing scrap collecting container on the surface of the cleaning roller. In the cleaning device 20, the polishing roller 22 is arranged so that the surface layer (polishing layer) thereof is in contact with the surface layer (elastic layer) of the cleaning roller 12. When polishing, the polishing roller 22 rotates at a speed (here, about 1000 to 2000 rpm) faster than the rotation speed of the cleaning roller 21 (here, about 100 to 300 rpm). As a result, the polishing roller 22 polishes the elastic layer 21b of the cleaning roller 21. At the same time, polishing scraps on the surface of the polishing roller 22 are blown off by a polishing scrap recovery blade 31 provided at a position substantially opposite to the polishing surface where the polishing roller 22 polishes the cleaning roller 21, and the polishing scraps are collected in the polishing scrap recovery container 32. Accumulate.

  The polishing member (polishing roller 22) is not limited to the example described above. For example, a plunge method in which a polishing surface is provided at a position corresponding to the entire sponge roller and polishing is performed in a lump. Alternatively, there may be mentioned a method of polishing by a traverse method in which only a part has a polishing surface and the polishing part itself moves in the longitudinal direction (axial direction) at any time.

  Further, the polishing scrap recovery means (polishing scrap recovery blade 31) on the surface of the cleaning roller 21 is not limited to the above-described example. For example, polishing waste can be removed by an appropriate method, that is, a recovery method by contact or non-contact using a blade of a metal material such as a urethane rubber material or SUS, or a contact type recovery means by a brush material. In addition, the contact-type recovery method in which the urethane material blade is brought into contact with the counter direction has a high recovery capability at the beginning of use, and a recovery capability of 70 to 95% can be obtained, but the urethane material blade itself is polished in the later stage of use. The collection capacity is reduced to 40-70%. On the other hand, the non-contact type recovery method using the SUS material blade does not cause a large difference in the recovery ability in the initial and late stages of use, but the recovery is slightly inferior compared with the initial contact type of about 50 to 70% regardless of the use state. It becomes ability.

Further, the capacity of the polishing dust collecting container 32 on the surface of the cleaning roller 21 is not generally defined because the diameter of the cleaning roller, that is, the polishing amount, differs depending on the target durable number. For example, in the system of the cleaning roller φ14 and the polishing roller φ14 in the image carrier unit targeting 200,000 sheets, a sufficient capacity can be secured at about 200 cm ³ . However, when the capacity is less than the required capacity, clogging of polishing dust occurs in the container, and rotation failure of the polishing roller or urethane sponge roller may occur, resulting in image failure due to poor cleaning of the charging roller. Therefore, the capacity of the collection container needs to be changed as needed according to the specifications.

  As shown in FIG. 5, an urging member 33 is provided on a fixed base 3B that can move back and forth (in the direction of arrow N) with respect to the cleaning roller 21, and the polishing roller 22 is provided at the tip of the urging member 33 via a bearing 3A. Is provided. The urging member 33 serving as a support pressure position adjusting unit includes a cylinder 33a, a spring 33b, and an adjusting screw 33c. As the strength of the spring 33b, 80 g to 300 g on one side is suitable, and an appropriate spring pressure is selected depending on the polishing roller to be used. According to such a configuration, the urging force can be increased or decreased by selecting the spring 33b, and the polishing roller 22 can be in contact with the cleaning roller 21 at all times during the polishing of the cleaning roller 21 by adjusting the adjustment screw 33c. . Further, the biasing member 33 makes it possible to easily adjust the load (pressure load), and the contact load and the position can be simply set so that the optimum polishing state can always be obtained in response to the polishing requirements of various cleaning rollers. Can be selected.

  Hereinafter, an Example is shown and Embodiment of this invention is described more concretely compared with a comparative example. In addition, the result of having compared the polishing power and cleaning capability of the Example shown below and a comparative example is shown in FIG. Also, the embodiments are not limited to the examples described below.

[Example 1]
The cleaning member (cleaning roller) applicable to the present invention can have an Asker C hardness of 50 to 90 °. The thickness, outer diameter, core diameter (shaft diameter), etc. of the elastic layer of the cleaning roller can be dealt with by changing the configuration of the polishing apparatus.

  As a cleaning member in this embodiment, a urethane sponge roller (elastic layer thickness 5.0 mm, outer diameter φ15, cored bar diameter φ5, length 230 mm) having an elastic layer of 68 ° Asker C hardness is as follows. Polished under conditions.

The rotation speed of the urethane sponge roller (cleaning roller) is 150 rpm, and is driven to rotate together with the charging roller in response to the driving force of the photosensitive drum. The contact width in the rotational direction of the polishing roller with the urethane sponge roller is preferably about 2 mm to 12 mm. When the contact width is less than 2 mm, the polishing force becomes weak, and when the contact width is 13 mm or more, the polishing amount increases and cannot be within the specified range. In this embodiment, the polishing roller is brought into contact with the urethane sponge roller by adjusting the support pressure so that the contact width is 6 mm, and the surface condition of the polishing roller is that of particle size # 80. Further, a non-contact type recovery method using a SUS material blade is adopted as the polishing scrap recovery blade, and the capacity of the polishing scrap recovery container is set to 200 cm ³ .

  The polishing roller polishes the elastic layer (collecting layer) at a rotational speed higher than the rotational speed of the cleaning roller (urethane sponge roller) after the power is turned on and other than the image forming operation. During the image forming operation, the polishing roller rotates at the same speed as the cleaning roller so as not to polish the elastic layer.

  Here, the timing of performing the polishing operation of the urethane sponge surface layer (elastic body layer) of the urethane sponge roller by the polishing roller is according to the flowchart shown in FIG. Sometimes.

  Here, a control configuration for controlling the operation of the polishing roller will be described with reference to FIG. The above-described operation control of the polishing roller 22 is performed by a control circuit 51 as a control unit shown in FIG. The polishing roller 22 rotates upon receiving a driving force from the driving unit 52. The operation of the drive unit 52 is controlled by the control circuit 51. The control circuit 51 controls the rotation speed of the polishing roller 22 by controlling the operation of the driving unit 52. Further, the control circuit 51 controls the operation of the polishing roller 22 based on detection information from the environment sensor 53 as temperature / humidity detection means for detecting temperature / humidity. The driving unit 52 that rotates the polishing roller 22 may have a configuration of a cleaning device or a configuration of an image forming apparatus. Further, the polishing roller 22 may be configured to rotate by receiving a driving force from a dedicated driving unit, or may be configured to rotate by receiving a driving force from another driving unit.

  As shown in FIG. 7, the control circuit 51 counts the number of durable sheets (number of printed sheets), which is the number of images formed since the previous polishing operation, and confirms how many durable sheets are counted at the aforementioned timing. (STEP 11, 12). Then, as the number of durable sheets from the previous polishing operation increases, the time for the polishing roller 22 to polish the collection layer of the cleaning roller 21 is lengthened. Here, further, the temperature / humidity detection result by the environmental sensor 53 is received according to the counted number of durable sheets (STEP 13, 14, 15), and the polishing time of the cleaning roller 21 by the polishing roller 22 is determined (STEP 16, 17, 18). Then, a polishing operation is performed.

  Specifically, when the number of durable sheets is 1000 or less (STEP 11), the temperature / humidity detection result by the environmental sensor 53 is received (STEP 13), and the higher the detected temperature / humidity, the more the polishing roller 22 becomes the cleaning roller. The time for polishing the 21 collection layer is lengthened. The control circuit 51 receives the temperature / humidity detection result from the environment sensor 53 and starts the polishing process. In the polishing process, the temperature / humidity detected by the environmental sensor 53 is received, the coefficient X is selected from the coefficient table shown in FIG. 8, and the cleaning roller 21 by the polishing roller 22 from the following predetermined formula (here, Formula 1-1). The polishing time (STEP 16) is calculated (determined) and the polishing operation is performed. Formula 1-1 is Y = 2.0X + 0.001C. Y is a polishing time (unit: second) by the polishing roller, X is a coefficient determined by temperature and humidity (see FIG. 8), and C is a durable number from the previous polishing operation.

  When the durable number exceeds 1000, it is confirmed whether or not the durable number is less than 2000 (STEP 12). When the durable number is less than 2000, the temperature and humidity detection result by the environmental sensor 53 is received (STEP 17), the polishing time (STEP 17) of the cleaning roller 21 by the polishing roller 22 is determined, and the polishing operation is performed. The polishing time here is calculated by Y = 2.5X + 0.001C (Formula 1-2).

  On the other hand, when the durable number is 2000 or more, the temperature / humidity detection result by the environmental sensor 53 is further received (STEP 15), the polishing time (STEP 18) of the cleaning roller 21 by the polishing roller 22 is determined, and the polishing operation is performed. Do. The polishing time here is calculated by Y = 3.0X + 0.001C (Formula 1-3).

  In addition, after the above-described polishing operation is completed, the polishing roller 22 rotates at the same speed as the rotation speed of the cleaning roller 21. This prevents the polishing roller 22 from polishing the collection layer of the cleaning roller 21.

  As polishing conditions of Example 1, the rotation speed of the polishing roller 22 was rotated at 1420 rpm, which is faster than the rotation speed of the cleaning roller 21, and rotated for about 4 seconds as one operation. As the polishing roller, a polishing roller having a particle size of # 80 was used. The contact width of the polishing roller with respect to the cleaning roller was set to 6 mm.

  A charging roller cleaning device including the polishing roller and the cleaning roller having the above-described configuration was attached to a modified iR3045 (manufactured by Canon Inc.). Under normal conditions (20 ° C / 50%), an image with an applied toner amount of 0.025 g / A4 size was subjected to a sheet passing image test (200K sheets) intermittently, and stains on the charging roller (50K, 100K). , 150K, 200K sheets).

  According to the present embodiment, by polishing the collection layer of the cleaning roller with the polishing roller, the surface layer having a reduced ability to collect deposits is scraped, and a new surface layer having the original collection ability is produced. The cleaning ability was restored. As a result, it was possible to maintain a stable cleaning ability over a long period of time, and to prevent image defects caused by a reduction in the cleaning ability.

[Example 2]
In Example 2, the particle size (surface state) of the polishing roller was changed to a polishing roller with fine abrasive particles such as # 80 to # 200. Other than that, examination similar to Example 1 mentioned above was performed. Also in this embodiment, it was possible to maintain a stable cleaning ability over a long period of time, and to prevent image defects due to a reduction in cleaning ability.

[Example 3]
In Example 3, the rotation speed of the polishing roller during polishing was changed from 1420 rpm to 1920 rpm. Other than that, examination similar to Example 1 mentioned above was performed. Also in this embodiment, it was possible to maintain a stable cleaning ability over a long period of time, and to prevent image defects due to a reduction in cleaning ability.

[Example 4]
In Example 4, the contact width of the polishing roller with respect to the cleaning roller was changed from 6 mm to 12 mm. Other than that, examination similar to Example 1 mentioned above was performed. Also in this embodiment, it was possible to maintain a stable cleaning ability over a long period of time, and to prevent image defects due to a reduction in cleaning ability.

[Comparative Example 1]
In Comparative Example 1, the cleaning device for the charging roller constituted only by the cleaning roller was used without using the polishing roller. Other than that, examination similar to Example 1 mentioned above was performed. With this configuration, the cleaning ability of the charging roller is low and the cleaning stability is deteriorated, resulting in poor durability stability.

[Comparative Example 2]
In Comparative Example 2, the particle size (surface state) of the polishing roller was changed to a polishing roller with fine abrasive particles such as # 80 to # 500. Other than that, examination similar to Example 1 mentioned above was performed. When this polishing roller is used, the polishing degree of the cleaning roller is lowered, the holes of the cleaning roller are clogged, and the cleaning ability is lowered. As a result, the cleaning ability of the charging roller was lowered, and an image defect due to uneven cleaning occurred.

[Comparative Example 3]
In Comparative Example 3, the rotation speed of the polishing roller at the time of polishing was changed from 1420 rpm to 200 rpm so as to approach 150 rpm that is the rotation speed of the cleaning roller. Other than that, examination similar to Example 1 mentioned above was performed. When carried out at this rotational speed of the polishing roller, the degree of polishing of the cleaning roller becomes low, the holes of the cleaning roller are clogged, and the cleaning ability is lowered. As a result, the cleaning ability of the charging roller was lowered, and an image defect due to uneven cleaning occurred. In order to polish the surface of the cleaning roller, it is important to increase the peripheral speed difference between the polishing roller and the cleaning roller.

[Comparative Example 4]
In Comparative Example 4, Y = 0.5X + 0.001C (from the above formulas 1-1, 1-2, and 1-3 so that the polishing time of the polishing roller when the power is turned on (outside of the image forming operation) is significantly shortened. Changed to equation 2). Other than that, examination similar to Example 1 mentioned above was performed. When the polishing time of the polishing roller is used, the cleaning roller becomes less polished, the cleaning roller hole is clogged, and the cleaning ability is lowered. As a result, the cleaning ability of the charging roller was lowered, and an image defect due to uneven cleaning occurred.

[Comparative Example 5]
In Comparative Example 5, Y = 10X + 0.001C (Equation 3) so that the polishing time of the polishing roller when power is turned on (outside of the image forming operation) is significantly increased. ). Other than that, examination similar to Example 1 mentioned above was performed. When this polishing roller is used for the polishing time, the cleaning roller has a high degree of polishing, and the thickness of the elastic layer (collecting layer) of the cleaning roller is greatly reduced. descend. As a result, the cleaning ability of the charging roller was lowered, and an image defect due to uneven cleaning occurred.

  As described above, by polishing the collection layer of the cleaning roller with the polishing roller, the surface layer of the cleaning roller having a reduced ability to collect deposits is scraped, and a new surface layer having the original collection ability is produced. The cleaning ability can be recovered. As a result, a stable cleaning ability can be maintained over a long period of time, and image defects due to a reduction in cleaning ability can be prevented.

[Other Embodiments]
In the above-described embodiment, the cleaning device that removes the adhering matter attached to the surface of the charging roller by contacting the surface is exemplified. However, the present invention is not limited to this. For example, an image of a photosensitive member or an intermediate transfer member. It may be a cleaning device that contacts the surface of the carrier and removes deposits adhered to the surface. Even if the present invention is applied to this cleaning device, the same effect can be obtained.

  In the above-described embodiment, the longer the number of durable sheets from the previous polishing operation, and the higher the temperature and humidity detected by the environmental sensor, the longer the time for the polishing roller to polish the collection layer of the cleaning roller. Although illustrated, it is not limited to this. For example, the configuration may be such that the longer the number of durable sheets from the previous polishing operation, the longer the time for the polishing roller to polish the collection layer of the cleaning roller. Alternatively, the higher the temperature and humidity detected by the environmental sensor, the longer the time for the polishing roller to polish the collection layer of the cleaning roller may be. The same effect can be obtained by this configuration.

  The image forming apparatus in which the above-described cleaning device is used may be another image forming apparatus such as a printer, a copying machine, or a facsimile machine, or another image forming apparatus such as a multi-function machine combining these functions. Good. Alternatively, an image forming apparatus that uses a recording material carrier and sequentially superimposes and transfers the toner images of the respective colors on the recording material carried on the recording material carrier. Alternatively, an image forming apparatus that uses an intermediate transfer member, sequentially transfers toner images of respective colors on the intermediate transfer member, and transfers the toner images carried on the intermediate transfer member collectively onto a recording material. Also good. The same effect can be obtained by applying the present invention to a cleaning device used in these image forming apparatuses.

DESCRIPTION OF SYMBOLS S ... Recording material 1 ... Photoconductor drum 2 ... Charging roller 20 ... Cleaning device 21 ... Cleaning roller 21a ... Shaft 21b ... Elastic body layer 22 ... Polishing roller 22a ... Shaft 22b ... Polishing layer 31 ... Polishing waste collection blade 32 ... Polishing waste Recovery container 51 ... control circuit 52 ... drive unit 53 ... environmental sensor

Claims (6)

A cleaning device that contacts the surface of an image carrier or the surface of a charging roller that charges the surface of the image carrier and removes deposits attached to the surface,
A cleaning member that contacts the surface of the image carrier or the charging roller and collects deposits attached to the surface; and a cleaning member that removes the deposits while rotating in contact with the surface;
A polishing member that contacts the collection layer of the cleaning member and polishes the collection layer;
A cleaning device comprising: In an image forming apparatus that forms an image using toner on the surface of an image carrier charged by a charging roller, and transfers the formed toner image to a transfer target.
A cleaning device that contacts the surface of the image carrier or the surface of a charging roller that charges the surface of the image carrier and removes deposits adhered to the surface, the surface of the image carrier or the charging roller A cleaning layer that contacts the surface and collects the adhering matter, and a cleaning member that contacts the surface and removes the adhering matter while rotating. A cleaning device having a polishing member that polishes the layer and rotates by receiving a driving force from a driving unit;
A control unit for controlling the rotational speed of the polishing member,
The control unit rotates the polishing member at a speed faster than the rotation speed of the cleaning member when polishing the collection layer.   The image forming apparatus according to claim 2, wherein the control unit rotates the polishing member at the same speed as a rotation speed of the cleaning member when the collection layer is not polished.   The polishing member rotates after the power is turned on and is rotated at a speed faster than the rotation speed of the cleaning member at a time other than the image forming operation, and polishes the collection layer. The image forming apparatus according to claim 3, wherein the image forming apparatus rotates at the same speed as the rotation speed of the cleaning member so as not to polish the layer.   The control unit counts the number of image formations from the previous polishing operation, and increases the time for the polishing member to polish the collection layer of the cleaning member as the number of image formations increases. Item 5. The image forming apparatus according to Item 4. A temperature / humidity detection means for detecting temperature / humidity, and a control unit for controlling the operation of the polishing member based on detection information of the temperature / humidity detection means,
6. The control unit according to claim 4, wherein the controller increases the time for the polishing member to polish the collection layer of the cleaning member as the temperature and humidity detected by the temperature and humidity detection unit increases. The image forming apparatus described.

Images