JP2011081428A - Image forming apparatus, image forming unit, and cleaning member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and image forming unit, capable of properly cleaning even a photoreceptor having a surface layer with high mechanical strength, and capable of obtaining an image with high image quality over long periods of time. <P>SOLUTION: The image forming apparatus includes: a photoreceptor drum 11 having a photoreceptor layer having a protective layer, which contains a siloxane-based resin having a crosslinked structure on the outermost surface, formed; and a cleaning device 30 removing toner left on the photoreceptor drum 11 after transfer. The cleaning device 30 includes a cleaning blade 33 provided by having a tip of the cleaning blade 33 brought into contact with the surface of the photoreceptor drum 11. A surface coat layer 33A, which is obtained by binding particulates together with a binder of room temperature cured type resin, is formed on the region in which the cleaning blade 33 is brought into contact with the photoreceptor drum 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus, an image forming unit, and a cleaning member used for a printer, a copying machine, a facsimile, and the like.

In electrophotographic image forming apparatuses used in printers, copiers, facsimiles, etc., electrostatic latent images formed on the surface of a photosensitive drum as an image carrier are visualized (toner images) by toner development. Further, this toner image is transferred to a recording paper or the like to obtain an image.
Such an image forming apparatus includes a cleaning device that removes toner remaining on the surface of the photosensitive drum after the toner image is transferred to a recording sheet or the like or an intermediate transfer member.
As a cleaning device, a blade system having excellent cleaning performance and reliability is often used. In the blade system, a cleaning blade formed of an elastic material such as rubber is pressed against the surface of the photosensitive drum and the remaining toner is scraped off (see Patent Documents 1 to 3 as a cleaning blade).

Meanwhile, in the field of electrophotographic image forming apparatuses, in recent years, there has been a great demand for speeding up of image forming processes, high image quality, and long life. However, particularly when speeding up, the image quality and the life of the photosensitive drum are often impaired. Specifically, by speeding up the image forming process, a functional member that is in contact with the surface of the photosensitive drum, such as a charging member of a contact charging device or a cleaning member (blade) of a cleaning device, Causes the photoreceptor to be scratched or worn. These scratches and wear cause image quality defects and shorten the life of the photosensitive drum.
In order to suppress the occurrence of such scratches and wear and to increase the speed, it has been proposed to use a resin having high mechanical strength for the photoreceptor. For example, Patent Document 4 discloses a photoreceptor in which a cured film containing a charge transporting organosilicon compound is formed on the outermost surface layer. According to this, the heat resistance and mechanical strength of the surface of the photoreceptor are improved, and generation of scratches and wear can be suppressed as compared with the conventional photoreceptor. As a result, high image quality can be maintained for a longer period, and the life can be extended.

JP-A-5-46056 JP 2001-166657 A JP2003-103686A JP 2001-249478 A

However, in the photoconductor having the resin film with high mechanical strength formed on the outermost surface layer as described above, the generation of scratches and wear can be suppressed, but the discharge product generated in the charging process or the like adheres firmly to the surface. For this reason, there is a problem that it is difficult to apply a blade-type cleaning device having excellent cleaning performance and reliability.
That is, the scraping ability of the blade is lowered due to the high mechanical strength of the surface layer, and the discharge product firmly adhered to the surface of the photoreceptor cannot be removed well by the blade. The residual discharge product causes the coefficient of friction on the surface of the photoreceptor to be extremely high and damages the cleaning blade. In particular, in the doctor blade system in which the cleaning blade is provided toward the upstream side in the rotation direction of the photosensitive member, there arises a problem that the cleaning blade is dragged by the photosensitive member and turned up.
Another problem is that the discharge product causes image defects called white spots under high temperature and high humidity.

The present invention has been made to solve such technical problems, and the object of the present invention is to be able to clean well a photoreceptor having a surface layer with high mechanical strength, An object of the present invention is to provide an image forming apparatus and an image forming unit capable of obtaining a high-quality image over a long period of time.
Another object of the present invention is to provide a cleaning member that can satisfactorily clean a photoreceptor having a surface layer with high mechanical strength.

For this purpose, the image forming apparatus of the present invention has an image carrier having a coating layer containing a crosslinked resin on the outermost surface, and a transfer on the image carrier by bringing a cleaning member into pressure contact with the surface of the image carrier. A cleaning device that removes residual toner, and the cleaning member includes a cleaning blade whose tip is pressed against the surface of the image carrier, and a surface coat layer formed at least on the tip of the cleaning blade, The tip of the cleaning blade is provided with a first surface pressed against the surface of the image carrier and a side extending from the surface of the image carrier and on the side where the image carrier is provided. And a second surface that is connected to the first surface and forms an edge portion together with the first surface, and the surface coat layer is formed on both the first surface and the second surface. This The features.
Here, the surface coat layer is formed of a room temperature curable resin, and the surface coat layer contains fine particles. The room temperature curable resin is a silicon resin. Furthermore, the fine particles have a volume average particle diameter of 0.05 to 1 μm. Further, the fine particles are characterized by being graphite. Further, the cleaning blade is formed in a plate shape by an elastic material. The elastic material is urethane rubber.

Further, another image forming apparatus of the present invention includes an image carrier having a coating layer containing a crosslinked resin on the outermost surface, and a cleaning device that removes transfer residual toner on the image carrier. The cleaning device includes a cleaning blade whose tip is pressed against the surface of the image carrier, a surface coat layer formed at least on the tip of the cleaning blade, and a blocking unit that forms a toner reservoir at the tip of the cleaning blade. The cleaning blade is provided with a first surface pressed against the surface of the image carrier, and extending in a direction away from the surface of the image carrier and an image carrier. And a second surface that is connected to the first surface and forms an edge portion together with the first surface, and the surface coat layer includes both the first surface and the second surface. Characterized in that it is formed in.
Here, the blocking means is a blocking member provided on the back side of the cleaning blade so as to press and bias the toner in the toner reservoir toward the image carrier. Further, the blocking member is characterized in that an opening of a predetermined size is formed at a position corresponding to the toner reservoir.

The image forming unit of the present invention is formed at least on the front end portion of an image carrier having a coating layer containing a resin having a crosslinked structure on the outermost surface , a cleaning blade whose tip is pressed against the surface of the image carrier. And a cleaning device that removes transfer residual toner on the image carrier, and is configured to be detachable from the main body of the image forming apparatus . A first surface pressed against the surface of the image carrier, and a first surface that extends in a direction away from the surface of the image carrier and is connected to the first surface on the side where the image carrier is provided. And a second surface that forms an edge portion together with the first surface, and the surface coat layer is formed on both the first surface and the second surface .

In addition, another image forming unit of the present invention includes an image carrier having a coating layer containing a cross-linked resin on the outermost surface, and a cleaning device that removes transfer residual toner on the image carrier. The cleaning device is configured to be detachable from the forming apparatus main body. The cleaning device includes a cleaning blade whose tip is pressed against the surface of the image carrier, a surface coat layer formed at least on the tip of the cleaning blade , and a cleaning blade . A blocking means for forming a toner reservoir at the tip, a first surface pressed against the surface of the image carrier at the tip of the cleaning blade, and a direction away from the surface of the image carrier And a second surface that is connected to the first surface on the side on which the image carrier is provided and forms an edge portion together with the first surface. Surface coating layer is characterized by being formed on both the first and second surfaces.

The cleaning member of the present invention includes a cleaning blade whose tip is pressed against the surface of the image carrier, and a surface coat layer formed at least on the tip of the cleaning blade. A first surface pressed against the surface of the carrier, and provided to extend in a direction away from the surface of the image carrier and connected to the first surface on the side where the image carrier is provided; And a second surface that forms an edge portion together with the first surface, and the surface coat layer is formed on both the first surface and the second surface.

According to the image forming apparatus of the present invention, it is possible to satisfactorily clean even a photosensitive drum having a surface layer with high mechanical strength, and it is possible to configure a highly durable image forming apparatus.
Further, according to the image forming unit of the present invention, it is possible to satisfactorily clean the photosensitive drum having the surface layer with high mechanical strength, and it is possible to configure a highly durable image forming unit.
Furthermore, according to the cleaning member of the present invention, it is possible to satisfactorily clean a photosensitive drum having a surface layer with high mechanical strength.

1 is a schematic configuration diagram of an image forming apparatus to which the exemplary embodiment is applied. It is sectional drawing which shows the conceptual structure of a cleaning apparatus. FIG. 3 is an enlarged view of the periphery of the cleaning blade in FIG. 2. It is sectional drawing which shows the conceptual structure of the cleaning apparatus of other embodiment. FIG. 5 is an enlarged view of the periphery of the cleaning blade in FIG. 4. It is a figure which shows a blocking plate.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram of a color image forming apparatus to which the exemplary embodiment is applied.
The image forming apparatus 10 has a drum-shaped photosensitive drum 11 as an image carrier having a photosensitive layer on the surface, a charger 12 that uniformly charges the photosensitive drum 11, and a uniformly charged body. A laser exposure device 13 as an image writing device that irradiates the photosensitive drum 11 with image light to form an electrostatic latent image, a developing unit 14 including four color developing devices 14a, 14b, 14c, and 14d, and a photosensitive member. An endless belt-shaped intermediate transfer belt 20 stretched around a path in contact with the drum 11, a primary transfer roll 15 that transfers a toner image formed on the photosensitive drum 11 to the intermediate transfer belt 20, and a transfer And a cleaning device 30 for removing toner remaining on the photosensitive drum 11 later. Further, a recording paper transport mechanism 40 that transports the recording paper P stored in the paper tray 41 and a fixing device 16 that fixes the toner image on the recording paper P are provided.

  The developing unit 14 contains black, yellow, magenta, and cyan color component toners, and develops the electrostatic latent image on the photosensitive drum 11 with a toner (a black developing device 14a, a yellow developing device). 14b, a magenta developing unit 14c, and a cyan developing unit 14d). These four developing units 14a, 14b, 14c, and 14d are provided on one base 14e that is rotationally driven, and sequentially approach and face the photosensitive drum 11. Then, the toner is transferred to a latent image corresponding to each color formed on the photosensitive drum 11 to obtain a toner image.

  The intermediate transfer belt 20 is wound around a primary transfer roll 15, a drive roll 21 that is rotationally driven, tension rolls 22 and 23 that adjust tension, and a backup roll 24. A secondary transfer roll 25 for transferring the toner image on the intermediate transfer belt 20 onto the recording paper P conveyed by the recording paper conveyance mechanism 40 is provided at a position facing the backup roll 24 across the intermediate transfer belt 20. ing. In addition, a toner removing device 18 that removes the toner remaining on the intermediate transfer belt 20 after the toner image is transferred onto the recording paper P by the secondary transfer roll 25 is provided.

  The recording paper transport mechanism 40 includes transport rolls 42, 43, and 44, paper guides 45 and 46 that guide the transport movement path, a discharge roll 47, a discharge tray 48, and the like. Then, the recording paper P stored in the paper tray 41 is moved from the secondary transfer position to the fixing device 16 to the secondary transfer position where the secondary transfer roll 25 and the backup roll 24 face each other with the intermediate transfer belt 20 interposed therebetween. It is transported from the fixing device 16 to the paper tray 41.

The image forming apparatus 10 forms a color image by operating as follows.
An electrostatic latent image corresponding to the image is written by the laser exposure unit 13 on the surface of the photosensitive drum 11 charged to a predetermined potential by the charger 12, and developed (toner) by the corresponding developing units 14a, 14b, 14c, and 14d. Imaged). The toner image is primarily transferred from the photosensitive drum 11 to the intermediate transfer belt 20 by a primary transfer bias applied to the primary transfer roll 15 at a primary transfer position where the photosensitive drum 11 and the intermediate transfer belt 20 are in contact with each other. The toner remaining on the photosensitive drum 11 after the primary transfer is removed by the cleaning device 30.
The toner image formation on the photosensitive drum 11 and the primary transfer process of the toner image are repeated by the number of colors, and the toner images of the respective colors are superimposed on the intermediate transfer belt 20 to form a color image.
The toner image primarily transferred to the intermediate transfer belt 20 in this way is transferred to the secondary transfer position where the secondary transfer roll 25 and the backup roll 24 face each other with the intermediate transfer belt 20 sandwiched by the rotation of the intermediate transfer belt 20. It is conveyed to. On the other hand, in synchronization with this, the recording paper P is transported to the secondary transfer position by the recording paper transport mechanism 40.
At the secondary transfer position, the toner image carried on the intermediate transfer belt 20 is electrostatically transferred onto the recording paper P by the action of a secondary transfer electric field formed between the secondary transfer roll 25 and the backup roll 24 (secondary transfer). Next transfer).
The recording paper P onto which the toner image has been transferred at the secondary transfer position is conveyed to the fixing device 16 by the recording paper conveyance mechanism 40, and the toner image is heated and pressed and fixed and discharged to the paper discharge tray 48. On the other hand, the residual toner remaining on the intermediate transfer belt 20 that has passed the secondary transfer position is removed by the toner removing device 18.

Hereinafter, the configuration of each part of the image forming apparatus 10 will be described in detail.
The photosensitive drum 11 has a photosensitive layer formed on the peripheral surface of a metal support (drum) such as aluminum. The photosensitive layer is a function separation type photoreceptor in which a charge generation layer and a charge transport layer are sequentially laminated, and a protective layer having excellent mechanical strength is formed on the outermost surface.

  The charge generation layer includes a charge generation material or a charge generation material and a binder resin. Charge generation materials include azo pigments such as bisazo and trisazo, condensed aromatic pigments such as dibromoanthanthrone, organic pigments such as perylene pigments, pyrrolopyrrole pigments, and phthalocyanine pigments, and inorganic pigments such as trigonal selenium and zinc oxide. All known ones can be used. As the charge generation material, an inorganic pigment is preferable when a light source with an exposure wavelength of 380 nm to 500 nm is used, and a metal and a metal-free phthalocyanine pigment are preferable when a light source with an exposure wavelength of 700 nm to 800 nm is used. Among these, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, or titanyl phthalocyanine is particularly preferable.

The binder resin for the charge generation layer can be selected from a wide range of insulating resins. It can also be selected from organic photoconductive polymers such as poly-N-vinyl carbazole, polyvinyl anthracene, polyvinyl pyrene and polysilane. Preferred binder resins include polyvinyl butyral resin / polyarylate resin (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin Insulating resins such as polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, polyvinyl pyrrolidone resin can be mentioned, but are not limited thereto. These binder resins can be used individually by 1 type or in mixture of 2 or more types.
The charge generation layer is formed by vapor deposition using the charge generation material or using a charge generation layer forming coating solution containing the charge generation material and a binder resin. The film thickness is preferably 0.1 to 5 μm, more preferably 0.2 to 2.0 μm.

  The charge transport layer includes a charge transport material and a binder resin, or includes a polymer charge transport material. Charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanyl, anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, xanthone compounds, benzophenone compounds , Electron transport compounds such as cyanovinyl compounds and ethylene compounds, triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, etc. Examples thereof include pore transporting compounds. These charge transport materials can be used singly or in combination of two or more, but are not limited thereto. The thickness of the charge transport layer is preferably 5 to 50 μm, more preferably 10 to 30 μm.

  The binder resin for the charge transport layer includes polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile. Copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinyl Carpazole, polysilane, polyester-based polymer charge transport material and the like can also be used. These binder resins can be used individually by 1 type or in mixture of 2 or more types. The blending ratio (mass ratio) of the charge transport material and the binder resin is preferably 10: 1 to 1: 5.

The protective layer contains a siloxane resin having a cross-linked structure with excellent mechanical strength. The resin for forming the protective layer is not limited to a siloxane resin, and any resin that can form a crosslinked structure may be used. Although various materials can be used, phenol resin, urethane resin, melamine resin, curable acrylic resin, siloxane resin, and the like are preferable. Among these, a siloxane resin is particularly preferable.
In addition, in order to give the protective layer resistance to abrasion, scratches, etc., conductive particles are dispersed, lubricating fine particles such as fluorine atom-containing resin and acrylic resin are dispersed, or a hard coat such as silicon or acrylic Agents can be used. Furthermore, the protective layer preferably contains a charge transport material in order to improve its electrical characteristics. In addition, as a charge transport material, what was mentioned as a constituent material of the said charge transport layer can be used, for example.

Thus, by using a resin having a crosslinked structure for the protective layer on the outermost surface of the photoconductor, the heat resistance and mechanical strength of the photoconductor surface are improved, and high image quality can be maintained over a longer period of time. Become. In the present embodiment, a siloxane-based resin is used, and a photoreceptor having this protective layer is hereinafter referred to as an SOC (Silicon Over Coat) photoreceptor.
Note that the photosensitive layer is not limited to the protective layer provided on the outermost layer of the function-separated type photoreceptor in which the charge generation layer and the charge transport layer are sequentially laminated as described above. For example, the functional separation type may be one in which a charge transport layer is used as the outermost layer without providing a protective layer and a resin having a crosslinked structure is contained therein. Even a single photosensitive layer having the charge generation layer and the charge transport layer as the same layer is itself the outermost layer if it contains a resin having a crosslinked structure.

The charger 12 forms an elastic layer made of SBR (styrene-butadiene rubber) containing carbon on a metal core, and an ECO (epichlorohydride) containing an ionic conductive material as a resistance layer on the elastic layer. A charging roll having a surface layer made of polyamide containing carbon black and SnO ₂ (conductive filler) formed thereon. The thickness of the elastic layer is 2.8 mm, the thickness of the resistance layer is 150 μm, the thickness of the surface layer is 10 μm, and the resistance value of the entire layer including the surface layer is adjusted in the range of 10 ⁷ to 10 ⁸ Ω. The charger 12 applies a DC voltage to the cored bar to uniformly charge the surface of the photosensitive drum 11. In addition to the contact type charging roll, a non-contact type charger such as a scorotron or a solid discharger may be used as the charger 12.
The laser exposure unit 13 repeatedly scans the laser beam of the light emitting element (LD) substantially perpendicularly to the rotation direction of the photosensitive drum 11 (arrow A in the figure), and the light emitting element is turned on / off based on the image signal. Thus, image exposure is performed on the photosensitive drum 11 that is driven to rotate.

The toner used in each developing unit 14a, 14b, 14c, 14d of the developing unit 14 is manufactured by an emulsion polymerization method, and has an average particle diameter of 6.5 μm and a shape factor of 132 ± 2. The shape factor is a value obtained by image analysis of an enlarged image of an optical microscope using an image analyzer Luzex III manufactured by Nireco Corporation, and is represented by the following equation.
Shape factor = (absolute maximum diameter of toner) ² / (projected area of toner) × π / 4 × 100

Here, the particle size of the toner greatly affects the image quality, and the larger the particle size, the rougher the image. Even if the toner has an average particle diameter of about 20 μm, there is no practical problem, but in order to increase the resolution of fine lines, it is desirable to use a toner having an average particle diameter of 10 μm or less. However, when the toner diameter is reduced, the physical adhesive force acting between the toner and the carrier is dominant and the developability is lowered. In addition, when the toner diameter is reduced, toner aggregation is likely to occur, resulting in handling problems. From such a point of view, the toner in the present exemplary embodiment preferably has an average particle size of 5 μm or more and 10 μm or less.
Further, an appropriate amount of fine particles (external additive) such as silica and titania having an average particle diameter of about 10 to 150 nm is externally added to the toner as a charge control agent and a transfer aid.
The toner is not limited to this production method, and may be produced by, for example, suspension polymerization, suspension granulation, dissolution suspension, kneading and pulverization.

The carrier is a resin-coated carrier having a resin coating layer in which a conductive material such as carbon black is dispersed on the surface of a ferrite core material, and has an average particle diameter of 45 μm.
As the developer in which the toner and the carrier are mixed, for example, a toner concentration (TC: Toner Concentration) of 8 wt% and a toner charge amount in the developer of 20 to 30 μC / g can be used. Here, TC is expressed by the following equation.
TC = (weight of toner contained in developer) / (total weight of developer) × 100
If the charge amount of the toner when the toner and the carrier are mixed to form a developer is too high, the adhesion force of the toner to the carrier becomes too high and the phenomenon that the toner is not developed is generated. On the other hand, if the charge amount is too low, the adhesion of the toner to the carrier is weakened, and toner cloud due to the free toner is generated, causing fogging in printing. From the viewpoint of good development by transferring the toner, it is desirable that the charge amount of the toner in the developer is in the range of 5 to 50 μC / g, preferably 10 to 40 μC / g in absolute value. The toner charge amount in this embodiment is 30 μC / g.

The intermediate transfer belt 20 is an endless belt having a thickness of 80 μm in which carbon black is dispersed in a polyimide resin. For example, the volume resistivity of the belt is 10 ⁹ Ωcm, and the surface resistivity is 10 ¹² Ω / □.
The primary transfer roll 15 is formed by forming a urethane foam layer on a metal core, and the resistance value of the roll is adjusted to 10 ⁸ Ω. Moreover, the outer diameter of the primary transfer roll 15 is 18.5 mm, for example.
The roll resistance value in the image forming apparatus 10 including the primary transfer roll 15 is set such that each roll is placed on a metal plate connected to the ground, a load of 500 g in total is applied to both ends of the roll, and the core metal and the metal plate of the roll. And a DC voltage of 1 kV is applied between the two and converted from the measured current value.
The secondary transfer roll 25 has a two-layer structure with an outer diameter of 28 mm, and has a thin surface layer with high resistance and an elastic layer having elasticity with resistance lower than that of the surface layer inside thereof. The surface layer has a volume resistivity in the range of 10 ⁸ to 10 ¹³ Ωcm, the resistance of the elastic layer is lower than the resistance of the surface layer, and the resistance value of the entire roll is adjusted to be in the range of 10 ⁸ to 10 ⁹ Ω. It is.

The fixing device 16 includes a heat roll that heats the toner image transferred onto the recording paper P, and a pressure roll provided to face the heat roll. Then, the recording paper P is pressed against the heat roll heated by the pressure roll, and the toner image is fixed on the recording paper P by heating and pressing.
The toner removing device 18 is a brush formed by winding a woven fabric in which a nylon fiber is woven around a metal core, for example, an outer diameter of 17.5 mm, a fiber thickness of 0.67 tex (6 denier), The pile length is 5.5 mm, and the amount of biting into the intermediate transfer member is set to about 1 mm. Then, the intermediate transfer belt 20 is rotationally driven in the direction opposite to the rotation direction (arrow B in the figure) to remove toner and paper dust. A flicker bar 19 is in contact with the brush so as to scrape off toner adhering to the brush fibers. The flicker bar 19 is coated with a fluororesin to prevent toner and the like from adhering to and accumulating on the surface.

Next, the cleaning device 30 which is a main part of the present embodiment will be described.
FIG. 2 is a cross-sectional view showing a conceptual configuration of the cleaning device 30. FIG. 3 is an enlarged view showing the periphery of the cleaning blade 33.
The cleaning device 30 includes a cleaner housing 31 that is disposed in the vicinity of the photosensitive drum 11 and opens to the side facing the photosensitive drum 11.
A seal member 32 is fixed to the lower opening end of the cleaner housing 31. The seal member 32 substantially closes the gap between the photosensitive drum 11 and the cleaner housing 31, and prevents waste toner and the like stored in the cleaning device 30 from leaking to the outside. For the sealing member 32, for example, a thermoplastic polyurethane film having a thickness of 0.2 mm is used.

In the cleaner housing 31, a cleaning blade 33 as a cleaning member is disposed downstream of the seal member 32 in the rotation direction of the photosensitive drum 11 (indicated by an arrow in the drawing). In addition, an auger 39 is disposed in the lower portion of the cleaner housing 31.
The cleaning blade 33 is fixed to the cleaner housing 31 via a support fitting 34, and is provided with its tip end in contact with the surface of the photosensitive drum 11.
The support fitting 34 has an L-shaped cross section and is fixed to the cleaner housing 31 by a set screw 35.

  In the cleaning device 30 having such a configuration, as shown in FIG. 2, the transfer residual toner T remaining on the surface of the photosensitive drum 11 is directly passed in front of the seal member 32 and scraped off by the cleaning blade 33. The transfer residual toner T thus scraped off is temporarily accommodated in the cleaner housing 31, and conveyed and discharged to the outside of the side of the cleaning device 30 by the auger 39. The cleaning device 30 is configured as at least a unit (process cartridge) integrated with the photosensitive drum 11 and is detachable from the image forming apparatus 10 in the unit state.

Here, the cleaning blade 33 is formed in a plate shape having a predetermined thickness by an elastic material. A surface coat layer 33 </ b> A is formed at least at a portion that contacts the photosensitive drum 11. In the present embodiment, the surface coat layer 33 </ b> A is formed on the tip portion of the cleaning blade 33 that contacts the photosensitive drum 11 and the tip surface continuous with the tip portion.
As the elastic material, for example, thermosetting urethane rubber having excellent mechanical properties such as wear resistance, chipping resistance, and creep resistance is used.
The surface coat layer 33A is obtained by binding fine particles with a binder of a room temperature curable resin (in other words, fine particles are encapsulated in a binder of a room temperature curable resin). The surface coat layer 33A is formed by applying a coating agent in which a binder of a room temperature curable resin and fine particles are mixed to a predetermined portion of the cleaning blade 33 and curing the binder.
The reason why the room temperature curable resin is used as the binder is that urethane rubber having low heat resistance is used for the cleaning blade 33. Urethane rubber is excellent in functionality, reliability, and processability, but has low heat resistance. Also, the room temperature curable resin is suitable as a surface coating material because it is excellent in flexibility and durability. As the room temperature curable resin, either a one-component room temperature curable resin or a two-component room temperature curable resin can be used.

Here, when the photoreceptor to be cleaned is an SOC photoreceptor, it is particularly preferable to use a silicon resin as the binder. Silicon resin has good compatibility with the SOC photoconductor which is the same material system, and good slidability can be obtained. However, the material is not limited to silicon, and may be a binder resin other than a silicon resin as long as the material is excellent in slidability such as fluorine.
Further, as fine particles mixed with the binder, for example, graphite is used. As a result, the lubricity of graphite allows sliding with the surface of the SOC photoconductor with low friction, and the graphite grinds the surface of the SOC photoconductor to remove the discharge products adhering to the surface of the photoconductor. Good cleaning properties can be maintained over a long period of time. The shape of the graphite is preferably scaly from the viewpoint of reducing the friction coefficient. Moreover, it is preferable that the volume average particle diameter is 0.05-1 micrometer. The reason for this will be described in detail in the section of test results of specific examples. The fine particles are not limited to graphite, but can be replaced as long as they have slidability and abrasiveness. For example, cerium oxide, silicon oxide, titanium oxide, aluminum oxide, etc. can be used.

The blending ratio of the fine particles is preferably 10 to 150 parts by weight with respect to 100 parts by weight of the binder resin. If the amount is less than 10 parts by weight, the effect of reducing the friction cannot be obtained. If the amount exceeds 150 parts by weight, the adhesion of the cleaning blade may be lowered, resulting in poor cleaning or sliding durability. It depends.
Further, the thickness of the surface coat layer 33A is preferably 0.5 to 5 μm. If the thickness is less than 0.5 μm, the strength may be insufficient and may be peeled off by sliding. On the other hand, if the thickness exceeds 5 μm, the flexibility is lowered, and the deformation followability as the cleaning blade 33 is deteriorated. It is because there is a possibility of producing.

Note that the blade pressurization method in the present embodiment employs a constant displacement method with a simple structure and low cost. For example, the applied pressure is set to 19.6 N / m (2 gf / mm). However, the blade pressing method is not limited to the constant displacement method, and a constant load method in which the contact pressure hardly changes with time may be used.
The cleaning blade 33 in this embodiment is a urethane rubber blade provided with a surface coat layer 33A. The blade material is a metal having elasticity such as a phosphor bronze plate or a SUS (stainless alloy) plate. A plate may be provided, and a surface coat layer may be provided on the surface. Even with such a configuration, since the slidability by the surface coat layer is good, the same cleaning performance can be obtained. According to this, the strength is higher than that of the rubber material, and the deterioration with time is small, so that the durability is superior.

Next, the results of tests conducted using specific examples will be described. In addition, refer to FIG. 1 and FIG.
Table 1 shows the results of cleaning performance evaluation by attaching the cleaning blade 33 according to the embodiment of the present invention to the photosensitive drum 11 having an outer diameter of 84 mm provided with the SOC photosensitive member.
The material of the cleaning blade 33 used was a 2 mm thick material made of thermosetting polyurethane rubber. A 2 μm-thick surface coat layer 33A containing graphite fine particles with different diameters was formed using a room temperature curable silicone resin as a binder, and the difference in effect due to the particle size of the fine particles was observed. The mixing ratio of the room temperature curable silicone resin and the graphite fine particles is 50 parts by weight of graphite fine particles with respect to 100 parts by weight of the room temperature curable silicone resin.
The volume average particle size of the fine particles is 0.012 μm, 0.04 μm, 0.05 μm, 0.06 μm, 0.1 μm, 0.4 μm, 1.0 μm, 1.2 μm, 1.5 μm, and 2.0 μm. It is.
The evaluation scale was initial cleanability. Specifically, three sheets of A3 paper were continuously passed to evaluate the presence or absence of toner slippage, and the presence or absence of turning-up when 1000 sheets of A3 paper were printed was confirmed.

  As a result, when the volume average particle size of the fine particles was less than 0.05 μm, blade turning occurred. This is presumably because the effect of reducing friction is reduced by reducing the state in which the fine particles themselves are in direct contact with the surface of the image carrier. Further, when the thickness exceeds 1 μm, the occurrence of defective cleaning was confirmed. This is considered to be caused by a decrease in toner blocking force by the cleaning blade 33. From these results, it was found that the volume average particle diameter of the fine particles is preferably 0.05 to 1 μm.

Next, another embodiment of the present invention will be described.
FIG. 4 is a cross-sectional view showing a conceptual configuration of the cleaning device 30 ′. FIG. 5 is an enlarged view of the periphery of the cleaning blade 33. Note that parts having the same functions as those in the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.
In the illustrated embodiment, a blocking plate 36 as a blocking member is provided on the back side of the cleaning blade 33 (the side opposite to the photosensitive drum 11).

6A and 6B are views showing the blocking plate 36. FIG.
As shown in FIG. 6A, the blocking plate 36 is formed in a thin plate shape having elasticity, for example, by a resin material such as polyurethane or PET, and the lower end portion is provided by being bonded to the seal member 32. . The tip part is elastically deformed in contact with the back surface of the cleaning blade 33 and is polymerized by about 2 to 10 mm. The longitudinal width of the blocking plate 36 (the length in the axial direction of the photosensitive drum 11) is substantially the same as the longitudinal width of the cleaning blade 33.
The blocking plate 36 forms a toner reservoir 37 surrounded by the surface of the photosensitive drum 11, the cleaning blade 33, and the seal member 32 at the tip of the cleaning blade 33.

  In such a cleaning device 30 ′, the untransferred toner T remaining on the surface of the photosensitive drum 11 passes through the seal member 32 as it is and is scraped off by the cleaning blade 33. The transfer residual toner T scraped off is blocked by the blocking plate 36 and stays in the toner reservoir 37 at the tip of the cleaning blade 33. When the residual toner T is filled in the toner reservoir 37 as the cleaning progresses, the blocking plate 36 presses the residual transfer toner T toward the photosensitive drum 11 by its elasticity, and the residual transfer toner T is applied to the tip of the cleaning blade 33. The external additive contained in is always supplied. Thus, the discharge product adhering to the surface of the photosensitive drum 11 is mechanically scraped and removed by the rubbing force of the external additive contained in the transfer residual toner T, and at the tip of the cleaning blade 33. Improves slidability. For this reason, it is possible to prevent the occurrence of white spots due to the discharge products and to perform good cleaning.

Table 2 shows the results of comparative evaluation by running tests with different configurations prepared in order to confirm the effect of maintainability according to the present embodiment.
The sample structure is as follows.
Type A: Conventional photoconductor + cleaning blade without surface coat layer TypeB: Conventional photoconductor + cleaning blade without surface coat layer + toner reservoir TypeC: SOC photoconductor + cleaning blade without surface coat layer TypeD: SOC photoconductor + Cleaning blade without surface coat layer + toner reservoir Type E: SOC photoreceptor + cleaning blade with surface coat layer Type F: SOC photoreceptor + cleaning blade with surface coat layer + toner reservoir Cleaning blade 33 is a thermosetting polyurethane. A 2 mm thick one made of rubber was used. The surface coat layer 33A was formed to have a thickness of 2 μm by using a room temperature curable silicone resin as a binder and containing graphite fine particles having a volume average particle size of 0.2 μm.

As a result, Type F (SOC photoconductor + cleaning blade with surface coat layer + toner reservoir) maintained good cleaning performance even after printing 400k sheets. In contrast, Type C (SOC photoconductor + cleaning blade without surface coat layer) and Type D (SOC photoconductor + cleaning blade without surface coat layer + toner reservoir) are bent when several tens to several thousand sheets are printed. Because of this, running was stopped.
In addition, Type B (conventional photoconductor + cleaning blade without surface coating layer + toner reservoir) in which Type A, which is the conventional structure itself, is provided with a toner reservoir, has 40 to 100k sheets although the maintainability is extended by about twice. In the meantime, cleaning failure occurred due to blade wear or blade chipping.
Therefore, it has been confirmed that the cleaning blade 33 according to the present embodiment can maintain the sustainability that is four times or more that of the conventional one.
Note that Type E (SOC photoconductor + cleaning blade having a surface coat layer) has the configuration of the above-described embodiment, but good cleaning performance was maintained even after printing 200 to 300 k sheets. As a result, it was confirmed that the cleaning blade 33 having the surface coat layer 33A can maintain more than twice the conventional maintainability even when no toner reservoir is provided.

  Here, as shown in FIG. 6B, an opening 36a may be formed in the blocking member 36 at a position corresponding to the toner reservoir. By thus providing the opening 36a, the toner accumulated in the toner reservoir 37 (see FIG. 5) can be replaced smoothly. If the toner flow stagnates in the toner reservoir 37, the toner and external additives aggregate to impair the function of the toner reservoir. Therefore, it is more preferable to provide the opening 36a. Further, by providing the opening 36a, even when a carrier or foreign matter enters the toner reservoir 37, it can be smoothly discharged.

  In the above-described embodiment, the present invention is applied to a color image forming apparatus using a rotary developing device. However, the target image forming apparatus is not limited to this. For example, the present invention may be applied to a monochrome copying machine or a tandem color image forming apparatus.

DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus, 11 ... Photosensitive drum (image carrier), 30, 30 '... Cleaning device, 33 ... Cleaning blade (cleaning member), 33A ... Surface coat layer, 36 ... Blocking plate (blocking) Member), 36a ... opening, 37 ... toner reservoir

Claims (18)

An image carrier having a coating layer containing a crosslinked resin on the outermost surface;
A cleaning device that presses a cleaning member against the surface of the image carrier to remove residual toner on the image carrier; and
The cleaning member is
A cleaning blade whose tip is pressed against the surface of the image carrier;
A surface coat layer formed at least on the tip of the cleaning blade;
With
At the tip of the cleaning blade,
A first surface pressed against the surface of the image carrier;
The image carrier is provided so as to extend away from the surface, and is connected to the first surface on the side where the image carrier is provided, and forms an edge portion together with the first surface. A second surface to be provided,
The image forming apparatus, wherein the surface coat layer is formed on both the first surface and the second surface. The image forming apparatus according to claim 1, wherein the surface coat layer is formed of a room temperature curable resin, and the surface coat layer includes fine particles. The image forming apparatus according to claim 2 , wherein the room temperature curable resin is a silicon-based resin. The image forming apparatus according to claim 2 , wherein the fine particles have a volume average particle diameter of 0.05 to 1 μm. The image forming apparatus according to claim 2 , wherein the fine particles are graphite. The cleaning blade, the image forming apparatus according to claim 1 to 5, characterized in that it is formed into a plate shape by an elastic material. The image forming apparatus according to claim 6 , wherein the elastic material is urethane rubber. An image carrier having a coating layer containing a crosslinked resin on the outermost surface;
A cleaning device for removing the transfer residual toner on the image carrier,
The cleaning device includes:
A cleaning blade whose tip is pressed against the surface of the image carrier;
A surface coat layer formed at least on the tip of the cleaning blade;
A blocking means for forming a toner reservoir at the tip of the cleaning blade;
With
At the tip of the cleaning blade,
A first surface pressed against the surface of the image carrier;
The image carrier is provided so as to extend away from the surface, and is connected to the first surface on the side where the image carrier is provided, and forms an edge portion together with the first surface. A second surface to be provided,
The image forming apparatus, wherein the surface coat layer is formed on both the first surface and the second surface. The blocking means is a blocking member provided on the back side of the cleaning blade so as to press and urge toner in the toner reservoir toward the image carrier. The image forming apparatus according to 8 . The image forming apparatus according to claim 9 , wherein the blocking member has an opening having a predetermined size at a position corresponding to the toner reservoir. An image carrier having a coating layer containing a crosslinked resin on the outermost surface;
Cleaning that has a cleaning blade whose tip is pressed against the surface of the image carrier and a surface coat layer formed at least on the tip of the cleaning blade, and removes transfer residual toner on the image carrier An image forming apparatus main body, and is configured to be detachable from the image forming apparatus main body.
At the tip of the cleaning blade,
A first surface pressed against the surface of the image carrier;
The image carrier is provided so as to extend away from the surface, and is connected to the first surface on the side where the image carrier is provided, and forms an edge portion together with the first surface. A second surface to be provided,
The image forming unit , wherein the surface coat layer is formed on both the first surface and the second surface . An image carrier having a coating layer containing a crosslinked resin on the outermost surface;
A cleaning device that removes the transfer residual toner on the image carrier, and is configured to be detachable from the image forming apparatus main body.
The cleaning device includes:
A cleaning blade whose tip is pressed against the surface of the image carrier;
A surface coat layer formed at least on the tip of the cleaning blade;
And blocked means to form a toner reservoir to the tip of the cleaning blade,
Equipped with a,
At the tip of the cleaning blade,
A first surface pressed against the surface of the image carrier;
The image carrier is provided so as to extend away from the surface, and is connected to the first surface on the side where the image carrier is provided, and forms an edge portion together with the first surface. A second surface to be provided,
The image forming unit , wherein the surface coat layer is formed on both the first surface and the second surface . A cleaning blade whose tip is pressed against the surface of the image carrier;
A surface coat layer formed at least on the tip of the cleaning blade;
With
At the tip of the cleaning blade,
A first surface pressed against the surface of the image carrier;
The image carrier is provided so as to extend away from the surface, and is connected to the first surface on the side where the image carrier is provided, and forms an edge portion together with the first surface. A second surface to be provided,
The cleaning member, wherein the surface coat layer is formed on both the first surface and the second surface. The cleaning member according to claim 13, wherein the surface coat layer is formed of a room temperature curable resin, and the surface coat layer contains fine particles. The cleaning member according to claim 14 , wherein the room temperature curable resin is a silicon-based resin. The cleaning member according to claim 14 , wherein the fine particles have a volume average particle diameter of 0.05 to 1 μm. The cleaning member according to claim 14 , wherein the fine particles are graphite. The cleaning blade, a cleaning member according to claim 13 to 17, characterized in that it is formed by urethane rubber.

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