JP2013137398A - Image forming apparatus and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of forming a favorable image.SOLUTION: An image forming apparatus includes: an image carrier on which an electrostatic latent image is formed; and a charging device for charging the image carrier. The charging device is an endless electrically charged belt that includes a conductive adhesive layer on which fibers are flocked by electrostatic flocking, and is endless and flexible. The endless electrically charged belt is formed by the steps of: forming sequentially an elastic release member and the conductive adhesive layer on an outer surface of a cylindrical base material; flocking the fibers on the conductive adhesive layer by the electrostatic flocking; and releasing the conductive adhesive layer on which the fibers are flocked by the electrostatic flocking from the release member. Further, the endless electrically charged belt is brought into surface contact with the image carrier to charge it.

Description

  The present invention relates to an electrophotographic image forming apparatus.

  Currently, image forming apparatuses such as electrophotographic copying machines and printers are widely used. For example, an image forming apparatus including a photosensitive drum and a charging device that comes into contact with the photosensitive drum is widely used. In this image forming apparatus, the charging device uniformly charges the photosensitive drum, and the charged photosensitive drum is irradiated with light (for example, laser light) to form an electrostatic latent image on the surface thereof. The electrostatic latent image is visualized by a developer and transferred to a recording material to form an image.

As the charging device described above, for example, a charging brush is known that includes a cylindrical shaft formed of metal or resin and a cloth having a brush layer wound around the shaft. Since the charging brush itself is cylindrical, and the photosensitive drum is also cylindrical, the contact width between the charging brush and the photosensitive drum (hereinafter referred to as nip width) tends to be small. For this reason, when a conventional charging brush is used, a charging failure may occur.
From such a background, a belt-shaped charging device has been proposed instead of the charging brush (see, for example, Patent Document 1).

JP 10-31344 A

However, the conventional belt-shaped charging device is composed of a magnetic brush layer and a brush support body in which the magnetic brush layer is implanted, and adheres the magnetic brush of the magnetic brush layer to the brush support body with an adhesive, A base material such as a polyimide resin is usually used for the brush support. Since such a base material lacks flexibility, even a belt-shaped charging device has a small nip width with respect to the photosensitive drum, which may cause charging failure.
Further, in the case of a conventional charging brush using a cylindrical shaft, a step is generated at the joint between the shaft and the cloth depending on the manufacturing method, and as a result, the charging may be uneven. For example, image spots may be formed in a halftone image.
From such a background, there is a demand for an image forming apparatus that can prevent the need for charging and can form a good image.

  The present invention has been made in view of such circumstances, and provides an image forming apparatus that prevents the occurrence of unnecessary charging and forms a good image.

  According to the present invention, at least an image carrier on which an electrostatic latent image is formed and a charging device that charges the image carrier are provided, and the charging device includes fibers that are electrostatically implanted in a conductive adhesive layer. An endless charging belt having endless flexibility, and the endless charging belt is formed by sequentially providing an elastic release member and a conductive adhesive layer on the outer surface of a cylindrical base material, The belt is obtained by electrostatically flocking the fiber on the adhesive layer, and further releasing the conductive adhesive layer on which the fiber is electrostatically flocked from the release member, and the image carrying An image forming apparatus is provided in which the image carrier is charged by contacting the body in a surface contact state.

  Further, in the image forming apparatus according to the present invention, the endless charging belt is formed by sequentially providing an elastic release member, a first adhesive layer, and a second adhesive layer on the outer surface of the cylindrical base material, The second adhesive layer is obtained by electrostatically flocking fibers, and further releasing the first adhesive layer and the second adhesive layer in which the fibers are electrostatically flocked from the release member. The first adhesive layer is a conductive adhesive layer containing an acrylic or rubber-based adhesive, and the second adhesive layer is a conductive adhesive layer containing a urethane-based adhesive It may be.

  According to such a configuration, since the first adhesive layer is excellent in adhesiveness, a uniform layer can be formed on the release member, while the second adhesive layer holds the fiber with sufficient strength. The charging device is in surface contact with the image carrier with a stable nip width, and its performance is stable even when used for a long time. For this reason, an image forming apparatus is provided in which the operation is stable for a long time and a good image can be formed over a long time.

  The endless charging belt is installed in a state where tension is applied by at least a pair of rotating shafts, and the pair of rotating shafts has a surface portion between the pair of rotating shafts in the endless charging belt, It may be provided so as to come into contact with the image carrier in a surface contact state.

  According to such a configuration, the nip width between the surface portion between the rotation shafts of the endless charging belt and the image carrier can be increased and the contact is stabilized. For example, the nip width between the charging device and the image carrier can be made larger than when the charging device is cylindrical. Further, when the charging device has a cylindrical shape, the position adjustment between the charging device and the image carrier has been complicated, but according to this configuration, not only the position adjustment is easy, but also the positional relationship fluctuates. However, the fluctuation can be easily absorbed. Therefore, an image forming apparatus in which the contact between the charging device and the image carrier is stable is provided.

  In the image forming apparatus according to the present invention, the release member may be made of a rubber-based resin layer.

  According to such a structure, since the said release member has the outstanding elastic characteristic, even if there exists a level | step difference in a cylindrical base material, the said release member can deform | transform and can absorb the level | step difference. For this reason, unevenness does not occur on the surface of the release member, and as a result, an endless charging belt having a smooth surface can be obtained. Therefore, the charging device employing this endless charging belt can provide an image forming apparatus capable of uniformly charging the image carrier and forming a good image.

  In addition, according to the present invention, at least an image carrier on which an electrostatic latent image is formed and a charging device that charges the image carrier are provided, and the charging device includes fibers that are electrostatically bonded to the conductive adhesive layer. A method of manufacturing an image forming apparatus having an endless flexible endless charging belt that has been planted, and a step of sequentially providing a release member having elasticity and a conductive adhesive layer on the outer surface of a cylindrical base material; A step of electrostatically flocking the fibers on the conductive adhesive layer, and a step of releasing the conductive adhesive layer on which the fibers are electrostatically flocked from the release member, An image forming apparatus manufacturing method for obtaining an endless charging belt is provided.

  In the image forming apparatus according to the present invention, the charging device is an endless flexible endless charging belt in which fibers are electrostatically implanted in a conductive adhesive layer, and the endless charging belt is formed of a cylindrical base material. After an elastic release member and a conductive adhesive layer are sequentially provided on the outer surface, the fibers are electrostatically flocked to the conductive adhesive layer, and the fibers are electrostatically flocked from the release member. Since the belt is obtained by releasing the conductive adhesive layer, the image carrier can be charged by a smooth (so-called seamless) belt with a smooth surface of the charging device. Therefore, the image forming apparatus according to the present invention can uniformly charge the image carrier.

Further, the endless charging belt is composed of the fibers and the conductive adhesive layer in which the fibers are electrostatically implanted, and does not use a so-called base material. It is easy to ensure the nip width of the body (that is, it is possible to sufficiently ensure the contact width between the charging device and the image carrier).
Furthermore, in the charging device of the image forming apparatus according to the present invention, the endless charging belt contacts the image carrier in a surface contact state to charge the image carrier, and the charging device and the image carrier are also included. And the endless charging belt uniformly contacts the image carrier to charge the image carrier. For this reason, the image carrier is stably charged.
Therefore, since the image forming apparatus according to the present invention can uniformly and stably charge the image carrier, according to the present invention, an image forming apparatus that can prevent the need for charging and can form a good image is provided. The
In addition, according to the present invention, there is provided a method for manufacturing an image forming apparatus capable of preventing the need for charging and forming a good image.

1 is a cross-sectional view for explaining a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view for explaining a configuration of a charging belt used in the image forming apparatus of FIG. 1. (A) shows an embodiment in which the adhesive layer is one layer, and (b) shows an embodiment in which the adhesive layer is two layers. FIG. 6 is a cross-sectional view for explaining a configuration of a charging device of an image forming apparatus according to a comparative example.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view for explaining the configuration of an image forming apparatus according to an embodiment of the present invention.

(First embodiment)
As shown in FIG. 1, an image forming apparatus according to an embodiment of the present invention includes a photosensitive drum 10 that is an image carrier for an electrostatic latent image, and a charging belt 20 that uniformly charges the surface of the photosensitive drum 10. At least.

  The photoconductor drum 10 is a drum-like (columnar shape) electrophotographic photoconductor, and is arranged to be rotatable in the direction of the arrow shown in FIG. The surface of the photosensitive drum 10 is uniformly charged by the charging belt 20, and an electrostatic latent image is formed on the surface of the photosensitive drum 10 by being irradiated with light by an exposure device 30 described later.

The charging belt 20 is an endless charging belt having endless flexibility, and is formed by electrostatically flocking fibers on a conductive adhesive layer. FIG. 2 shows the configuration of the charging belt 20 of the present embodiment.
FIG. 2 is a cross-sectional view for explaining the configuration of the charging belt used in the image forming apparatus of the present embodiment. 2A shows an embodiment in which the adhesive layer is one layer, and FIG. 2B shows an embodiment in which the adhesive layer is two layers. Here, FIG. 2 shows the charging belt 20 in a state where no tension is applied, and is a view showing the charging belt 20 manufactured using a cylindrical base material to be described later. It has a cylindrical shape.

  As shown in FIG. 2A, the charging belt 20 includes a brush layer 21 composed of brush bristles and a conductive adhesive layer 22 in which the brush bristles are electrostatically implanted.

  The brush layer 21 is composed of a large number of brush hairs that are implanted substantially perpendicularly to the surface of the conductive adhesive layer 22. The brush bristles are made of a conductive yarn having a uniform dispersion structure in which a conductive material such as carbon is uniformly dispersed in a material such as nylon, polyester, vinylon, or aramid (aromatic (aromatic) polyamide). The configuration of the brush bristles is not limited to such a configuration. In addition, the brush bristles are conductive yarns of a composite structure in which the yarn surface of a material such as nylon or polyester is covered with the same conductive material, and carbon in acrylic fibers. May be a conductive yarn having a carbon array fiber structure in which is arranged. The material is selected in consideration of whether it is a positive side material or a negative side material in the charging system, according to the specifications of the charging device such as the magnitude and uniformity of charging.

  Moreover, the length of a bristle is not specifically limited, For example, Preferably it is 0.3-3.5 mm, More preferably, it is 0.5-2.5 mm. Within such a range, the contact width (hereinafter referred to as “nip width”) between the charging belt 20 and the photosensitive drum 10 is stable, and the surface contact with the photosensitive drum 10 is good.

  Further, the shape of the bristles is not particularly limited. In this embodiment, the cross-sectional shape of the brush bristles is a circular shape, but may be a flat shape, a boomerang shape, or a star shape (for example, a shape in which convex portions extend radially from the center toward six vertices). .

The resistance value of the bristles is not particularly limited, but in order to keep the charging performance of the charging device good, for example, the volume resistance value of the bristles is preferably 1 × 10 ⁴ to 1 × 10 ⁶ Ω · cm.
Here, the volume resistance value is measured, for example, by bundling 100 brush hairs having a length of 10 cm and bonding both ends thereof to a metal terminal with a conductive adhesive to produce a measurement sample. By measuring the electrical resistance of the sample.

  On the other hand, the conductive adhesive layer 22 is a layer for fixing the end portion (bottom surface) of the bristles and contains a conductive material and an adhesive. The conductive adhesive layer 22 is formed using, for example, a material containing an adhesive mainly composed of acrylic resin, vinyl acetate, polyurethane, synthetic rubber, natural rubber, and the like, and a conductive filler.

  The adhesive contained in the conductive adhesive layer 22 is not particularly limited, and includes, for example, at least one of acrylic resin, vinyl acetate, polyurethane, synthetic rubber, natural rubber, and the like as a main component. Preferably, acrylic resin, urethane resin, and rubber are the main components, and more preferably, urethane resin and rubber are the main components. For example, an adhesive containing 30 to 60% by mass of any one of acrylic resin, urethane resin, and rubber with respect to the entire adhesive is used.

  As an adhesive mainly composed of an acrylic resin, an adhesive activated by redox (oxidation reduction) and a cyanoacrylate adhesive are known, and any of these adhesives may be used (or These may be used in combination). For example, the main component of the adhesive activated by redox (oxidation reduction) is an elastomer (chlorosulfonated polyethylene, polyurethane, NBR, SBR, or the like), and includes methyl methacrylate as a monomer. The cyanoacrylate adhesive is, for example, a cyanoacrylate monomer as a main component, and includes a stabilizer, a thickener, a plasticizer, and the like. Examples of the cyanoacrylate monomer include methyl cyanoacrylate, ethyl, isobutyl and the like, and methyl cyanoacrylate and ethyl are generally used. A cyanoacrylate monomer may be used alone or in combination of two or more of these materials.

As adhesives mainly composed of urethane resin, polyurethane adhesives such as polyisocyanate adhesives, prepolymer adhesives, thermoplastic polymer adhesives and the like are known, and any of these adhesives may be used (or These may be used in combination). For example, polyisocyanate includes triphenylmethane-p, p ', p "-triisocyanate, hexamethylene diisocyanate, diphenylmethane-4,4'-diisocyanate, toluene diisocyanate, etc. In addition to these polyisocyanates, resins such as polyacrylates, epoxies, xylenes, and polyamides may be used as the polymer alone or in combination of two or more. The prepolymer is a urethane prepolymer that is a partial product of a polyisocyanate and a polyhydroxy compound, and the prepolymer adhesive is based on this (for example, used alone) and is used together with a curing agent. The thermoplastic polymer is This is a linear polymer of terminal OH group produced by reaction of diisocyanate with bi- or higher functional polyester and polyether, and is called diisocyanate-modified polymer.The main component of thermoplastic polymer adhesive is diisocyanate-modified polymer. Used as
In order to improve workability (for example, to reduce viscosity and improve applicability), adhesives mainly composed of a urethane resin include methylene chloride, methyl ethyl ketone, carbon tetrachloride, trichloroethylene, acetone and the like. A solvent may be included and a filler may be included. Examples of the filler include asbestine, carbon black, titanium dioxide, chalk, and clay.

  The adhesive mainly composed of rubber includes, for example, chloroprene rubber, nitrile rubber, styrene / butadiene rubber, styrene block rubber, urethane rubber or butyl rubber as a main component, a synthetic resin for improving adhesiveness, Fillers and stabilizers are included. To further illustrate, an adhesive containing chloroprene rubber as a main component is chloroprene rubber, magnesium oxide, activated zinc white, alkylphenol resin, adhesive resin (e.g., toluene, MEK, ethyl acetate, n-hexane, etc.). A terpene resin) and, if necessary, a filler (eg, calcium carbonate) is dissolved and dispersed. Adhesives mainly composed of nitrile rubber dissolve and disperse nitrile rubber, sulfur, zinc white, phenol resin, chlorinated rubber, if necessary, in solvents (acetone, MEK, ethyl acetate, etc.) Is produced. There is no particular limitation as long as it is an adhesive mainly composed of such a rubber, and any adhesive may be used as long as it is an adhesive listed here (or a combination thereof may be used). ).

  Moreover, at least 1 or more types of electroconductive powders, such as a metal and carbon (carbon), are used for an electroconductive filler, for example. The conductive powder is not particularly limited as long as it is a conductive powder, for example, a metal powder such as Ag, Pt, Au noble metal powder, Cu, Ni, Fe, Cr, Co, Al, Sb, Mo or the like Alloy powders and oxide powders. Examples of carbon powder include carbon black, carbon fiber, and graphite particles. In addition, since the conductive powder may be a fiber or the like, a non-conductive powder (glass beads, titanium oxide powder, etc.) whose surface is coated by sputtering, vapor deposition, plating, etc. is used. May be. In addition, a conductive polymer material such as polyaniline or polypyrrole may be used. You may use the powder of the material quoted here individually or in combination of 2 or more types.

  The conductive filler is preferably contained in the adhesive described above in an amount of 0.5 to 5.0 mass%, more preferably 3.0 to 4.0 mass%. For example, when the conductive filler is carbon, urethane resin or rubber is contained in the main component adhesive in an amount of 0.5% by mass or more. (Here, the content is a numerical value when the total of the adhesive and the conductive filler is 100 parts by mass.)

For example, the conductive adhesive layer 22 has a thickness of 100 to 250 μm in a dry state. The thickness of the conductive adhesive layer 22 is preferably 100 to 250 μm, more preferably 150 to 200 μm. If it is such thickness, while being excellent in a softness | flexibility, the charging belt excellent also in the mold release property between the mold release members 23 mentioned later is obtained.
The above thickness is a value when the adhesive is dried and cured to form the conductive adhesive layer 22.

  The conductive adhesive layer 22 preferably has a volume resistance value of 0.1 to 10 Ω · cm by adopting the above-described conductive filler content and layer thickness. Here, the volume resistance value is measured, for example, by preparing a film-like sample and using a four-terminal method.

  Since the charging belt 20 is formed of the material as described above, it has flexibility. For example, the obtained charging belt 20 can be bent without being bent even when a 90-degree bending test is performed on a cylinder having a diameter of 5 to 10 mm. Thus, the charging belt 20 is rich in flexibility and suitable for the belt.

  The charging belt 20 is endless and so-called seamless. That is, the charging belt 20 is a belt without a seam. More specifically, the charging belt 20 has substantially the same structure (thickness and layer structure) at any cylindrical portion.

  The charging belt 20 having such a configuration is obtained by the following manufacturing method. Hereinafter, a description will be given with reference to FIG. Here, in FIG. 2, elements constituting the charging belt 20 are indicated by solid lines, and elements used in the manufacturing process are indicated by dotted lines.

First, the cylindrical member 24 is prepared as a base material. As the cylindrical member 24, for example, a cardboard is used in which cardboard is rolled into a cylinder and the front surface and the back surface are joined at the end of the cardboard (the joint has a step). The cross-sectional shape is a circle or an ellipse, for example, a circle having a diameter of 30 to 130 mm. In the present embodiment, a hollow example is described, but a solid cylindrical member 24 may be used. For example, a solid cylindrical rod formed of a metal material such as SUS may be used.
In addition, since the work efficiency is good when an electrostatic field is applied to the cylindrical member 24 in the electrostatic flocking process described later, the material of the cylindrical member 24 is preferably a conductive material.

  Next, a release member 23 having elasticity is provided on the outer peripheral surface of the cylindrical member 24. The method is not particularly limited. For example, the release member 23 formed of a film-like (layer) and cylindrical bag having a thickness of 0.1 to 0.5 mm and made of synthetic rubber is used as the outer peripheral surface of the cylindrical member 24. The release member 23 is provided on the outer peripheral surface of the cylindrical member 24 by covering the surface.

The material of the release member 23 is preferably rubber (natural rubber or synthetic rubber), more preferably silicon rubber or polyurethane rubber. Here, the rubber includes, for example, natural rubber and synthetic rubber, and the synthetic rubber includes, for example, chloroprene rubber, nitrile rubber, ethylene propylene rubber, chlorosulfonated polyethylene rubber, polyurethane rubber, fluorine rubber, silicone rubber, styrene.・ Butadiene rubber, butadiene rubber, isoprene rubber, butyl rubber, acrylonitrile butadiene rubber, polysulfide rubber, phosphazene rubber, acrylic rubber, epichlorohydrin rubber, etc. are applicable. 23 materials may be used.
Since such a material has elasticity, even if there is a step on the surface of the cylindrical member 24, the step can be absorbed and the surface of the release member 23 can be made smooth.
Since the release member 23 may be a material having elasticity, it is not limited to rubber, and may be formed of an elastomer other than rubber (a polymer material exhibiting elasticity). For example, the release member 23 may be formed of a thermoplastic elastomer (a thermoplastic elastomer such as polystyrene, polyolefin, polyester, polyurethane, polyvinyl chloride, or polyamide). In addition to the elastomer, the release member 63 may be formed of a polyester resin.

  The release member 23 is preferably a film having a thickness of 0.05 to 1.0 mm. When the release member 23 having such a thickness is used, even if the cylindrical member 24 has a step, the unevenness can be absorbed. Moreover, the release member 23 is more preferably 0.05 to 0.5 mm in thickness, and still more preferably 0.05 to 0.3 mm. With the release member 23 having such a thickness, for example, even if the step is 0.05 to 0.1 mm, the step can be absorbed and the surface can be smoothed. The layer having such a thickness may be formed by applying the material of the release member 23 on the surface of the cylindrical member 24.

Here, the “release” property of the release member 23 is also for the cylindrical member 24. In order to have such a “release” property, the cylindrical member 24 may be provided with a silicon coat or a fluororesin coat.
Further, since the conductive adhesive layer 22 is finally released from the release member 23, the “release” property of the release member 23 is also for the conductive adhesive layer 22. When the conductive adhesive layer 22 is an acrylic resin, rubber can be mentioned as a material having this “releasing” property.

  Next, the conductive adhesive layer 22 is provided on the release member 23. A method of providing the conductive adhesive layer 22 is not particularly limited, but for example, a conductive adhesive is applied on the release member 23 by a screen printing method or an inkjet method.

  The conductive adhesive layer 22 is applied so as to have the thickness described above. The thickness of the conductive adhesive layer 22 is adjusted by adjusting the coating speed and the viscosity of the adhesive.

  Next, fibers that become brush hairs are electrostatically implanted in the conductive adhesive layer 22. Specifically, a group of bristles having a predetermined raised length is arranged at a position facing the conductive adhesive layer 22, and a high-voltage electrostatic field is applied (for example, the cylindrical member 24 is on the positive electrode side). Voltage is applied to the brush to charge the bristles to the negative electrode side). Then, the bristle is attracted to the cylindrical member 24 by electrostatic attraction force, and the bristle sticks perpendicularly to the surface of the conductive adhesive layer 22 that is the surface of the cylindrical member 24. As a result, the brush hair is electrostatically implanted in the conductive adhesive layer 22. Thereby, the brush layer 21 is formed on the conductive adhesive layer 22.

  Next, after the conductive adhesive layer 22 is cured, the conductive adhesive layer 22 in which fibers that are brush hairs are electrostatically implanted is released from the release member 23. For example, when the cylindrical member 24 is pulled out from the release member 23 in the axial direction, the release member 23 made of rubber resin contracts, and therefore, the conductive adhesive in which brush hairs are electrostatically implanted from the release member 23. Layer 22 releases. Thereby, the charging belt 20 shown in FIG. 2A is obtained.

  Since the charging belt 20 obtained by the above steps electrostatically implants fibers in the conductive adhesive layer 22 via the release member 23, even if there is a step in the cylindrical member 24, it is affected by the step. Therefore, the conductive adhesive layer 22 having a smooth surface is provided. Furthermore, since a base material is not used, it is rich in flexibility as compared with a conventional charging device.

For example, although the manufacturing method of the conventional charging belt is not clear from Patent Document 1, among the manufacturing methods of the following (1) to (4), which is a manufacturing method of a tubular flocked product such as a lens hood for a camera, It is assumed that the charging belt is manufactured in (1) to (3).
(1) A release film is wound around a molding cylinder such as cardboard, and a liquid hot melt is applied to the release film to form a heat-sensitive adhesive layer.
(2) Furthermore, by forming a short fiber flocking layer by flocking short fibers in the heat-sensitive adhesive layer, a cylindrical flocking sheet comprising a heat-sensitive adhesive layer and a short fiber flocking layer is formed,
(3) Next, the cylindrical flocking sheet is released from the release film,
(4) Next, the cylindrical flocking sheet is extrapolated so as to contact the outer surface of the cylindrical member, the thermal adhesive layer of the cylindrical flocking sheet is heated to weld the thermal adhesive layer to the cylindrical member, and the cylindrical flocking sheet is It is made to adhere to a cylindrical member.

  However, when a charging belt is manufactured using the manufacturing methods (1) to (3) described above, a step may occur in the cylindrical flocking sheet due to the surface shape of the molding cylinder. For example, when the molding cylinder is formed of cardboard, a step is generated at the joint, and a step may also be generated in the cylindrical flocking sheet. Therefore, when an image is formed by an image forming apparatus using this cylindrical flocking sheet, Charging may be uneven at the level difference, and for example, image spots may be formed in a halftone image.

  On the other hand, the charging belt of the image forming apparatus according to the present embodiment is provided with the release member 23 having elasticity on the outer peripheral surface of the cylindrical member 24, and the conductive adhesive layer 22 is provided on the release member 23. After the fibers that become brush hairs are electrostatically implanted in the conductive adhesive layer 22 and the conductive adhesive layer 22 is cured, the conductive adhesive layer 22 in which the brush hairs are electrostatically implanted is released from the release member 23. Therefore, the surface is smooth and has no step (or almost no step). For this reason, the image forming apparatus according to the present embodiment can uniformly charge the photosensitive drum.

In addition, as a method for producing a conventional charging brush, there is a method of winding a flocked sheet consisting of a base material and brush hair in which fibers are planted on an adhesive layer on the base material in a cylindrical shape, and joining the end portions thereof, It is conceivable to apply this to a charging belt.
However, even in this manufacturing method, a level difference may occur at the joint portion of the flocked sheet, and image spots may be formed in the formed image in the same manner as in the manufacturing methods (1) to (3) above. .
On the other hand, the charging belt of the image forming apparatus according to the present embodiment forms a cylindrical belt using the shape of the cylindrical member 24 without joining the end portions of the sheet, so there is no seam. It becomes an endless belt. Moreover, since it is obtained by the manufacturing method described above, the endless belt has a smooth surface and no steps (or almost no steps). Furthermore, since no base material is used, the cost can be reduced and the flexibility is higher than that of a conventional charging device.

  Thus, according to the manufacturing method described in this embodiment, an endless charging belt having a smooth surface and high flexibility can be obtained.

The charging belt 20 is installed in a state where tension is applied by at least a pair of rotating shafts.
More specifically, as shown in FIG. 1, the charging belt 20 is installed in a state where tension is applied by a pair of rollers 26 and 27. Here, the rollers 26 and 27 are so-called shafts and rotating shafts (the charging belt 20 has a flat belt shape, and may be called a belt wheel).

  The rollers 26 and 27 are disposed so that the outer periphery thereof is substantially in contact with the tangent line of the outer periphery of the photosensitive drum 10, and are rotatably supported so as to function as a rotation shaft. As shown in FIG. 1, since the charging belt 20 is hung on the rollers 26 and 27 by the open belt, when the charging belt 20 moves, the rollers 26 and 27 rotate in the same direction. When the charged belt 20 to which tension is applied contacts the rotating photosensitive drum 10, the charging belt 20 and the rollers 26 and 27 rotate in accordance with the rotation.

  Since the outer periphery of the rollers 26 and 27 is substantially in contact with the tangent line of the outer periphery of the photosensitive drum 10, the surface portion between the pair of rollers 26 and 27 in the charging belt 20, that is, the surface of the charging belt 20 between the rollers 26 and 27 is photosensitive. It comes into contact with the body drum 10 in a surface contact state. As described above, the charging belt 20 is flexible and does not use a base material (configuration consisting of the brush layer 21 and the conductive adhesive layer 22). It is possible to make close contact according to the surface shape of the photosensitive drum 10. Therefore, for example, even if the positional relationship between the charging belt 20 and the photosensitive drum 10 is slightly inclined toward the axial direction of the photosensitive drum 10, the charging belt 20 is in a state where the photosensitive drum 10 is in surface contact. Will abut.

  Here, the nip width between the charging belt 20 and the photosensitive drum 10 is preferably in the range of 5 to 100 mm, and more preferably in the range of 10 to 20 mm. In order to realize such a nip width, for example, the outer periphery of the rollers 26 and 27 may be disposed closer to the photosensitive drum than the tangent to the outer periphery of the photosensitive drum 10.

  In addition, one or both of the rollers 26 and 27 are electrically connected to a voltage applying device 25 (for example, a power source that applies a DC voltage). For this reason, a voltage is applied to the brush layer 21 of the charging belt 20. As described above, since the charging belt 20 comes into contact with the photosensitive drum 10 in a surface contact state, the surface of the photosensitive drum 10 is uniformly charged by the brush layer 21 to which a voltage is applied.

  The charging belt 20 having the above-described configuration has a smooth surface, no level difference, is highly flexible, and further contacts the photosensitive drum 10 in a surface contact state. The nip width with the charging belt 20 is increased, and the photosensitive drum 10 is uniformly and stably charged. For this reason, the image forming apparatus according to the present embodiment provides an image forming apparatus in which image defects (for example, image spots) are unlikely to occur.

The photosensitive drum 10 and the charging belt 20 have been described with respect to the configuration of the image forming apparatus according to the present embodiment. However, as a matter of course, a configuration well known in the image forming apparatus field may be further included. That is, the image forming apparatus of the present embodiment further includes an exposure device 30 that irradiates light on the photosensitive drum 10 to form an electrostatic latent image corresponding to the image signal on the surface of the photosensitive drum 10, and the photosensitive drum. A developing device 40 that visualizes the electrostatic latent image formed on the toner 10 as a developer image (toner image), a transfer brush 50 that transfers the developer image on the photosensitive drum 10 to a recording sheet, and a photosensitive member. A cleaning device 60 that removes developer, paper dust, and the like remaining on the drum 10 and a conveyance belt 7 that conveys recording paper for transferring a developer image are provided. The cleaning device 60 includes a cleaning brush 61, a solid A lubricant supply device 62 and a cleaning blade 63 may be provided.
These devices (configurations) are arranged in the order of the charging belt 20, the exposure device 30, the developing device 40, the transfer brush 50, the transfer brush 50 and the conveying belt 7, and the cleaning device 60 along the outer periphery of the photosensitive drum 10. The photosensitive drum 10 is arranged in the rotation direction.

(Second Embodiment)
Although the case where the charging belt in the image forming apparatus has one conductive adhesive layer has been described in the first embodiment, this conductive adhesive layer may be configured by a plurality of adhesive layers. Next, the case where the conductive adhesive layer is formed of two layers will be described with reference to FIG. FIG. 2B shows an embodiment in which the adhesive layer has two layers.

  As shown in FIG. 2B, the charging belt in the image forming apparatus of the second embodiment is an endless charging belt having endless flexibility as in the case of the first embodiment. Unlike the case of the first embodiment, the conductive adhesive layer is formed of the first conductive adhesive layer 22A and the second conductive adhesive layer 22B, and the fibers are electrostatically flocked to the second conductive adhesive layer 22B. Yes. Since the configuration of the second embodiment is substantially the same as that of the first embodiment, the description of the same configuration is omitted, and the configuration different from the first embodiment will be described below.

  The first conductive adhesive layer 62A is formed of a conductive adhesive containing an acrylic adhesive. The material of the first conductive adhesive layer 62A is not particularly limited, but may include a rubber adhesive instead of the acrylic adhesive, or may be formed of an adhesive other than these. Specifically, for example, the first conductive adhesive layer 62A is formed of a material containing an adhesive mainly composed of butadiene resin and a conductive filler. Among such adhesives, an adhesive including an acrylic or rubber adhesive is particularly preferable, and an adhesive including a rubber adhesive is more preferable. If it is such an adhesive agent, it will be excellent in adhesiveness and it will be easy to form a layer on a mold release member. For example, an adhesive containing 50% by mass of butadiene resin is used. (Here, the content is a numerical value when the total of the adhesive and the conductive filler is 100 parts by mass.)

  As in the first embodiment, at least one or more kinds of conductive powders such as metal and carbon are used for the conductive filler contained in the first conductive adhesive layer 22A (for example, carbon is used). The content of the conductive filler is also the same as in the first embodiment.

The first conductive adhesive layer 22A preferably has a thickness of 50 to 100 μm, more preferably 50 to 75 μm. With such a thickness, a charging belt excellent in flexibility can be obtained.
The thickness of the first conductive adhesive layer 22A is also a value when the adhesive is dried and cured to form the conductive adhesive layer 22 as in the first embodiment.

The second conductive adhesive layer 22B is formed of a conductive adhesive layer containing a urethane-based adhesive. More specifically, for example, the second conductive adhesive layer 22B is formed of an adhesive containing a urethane resin emulsion as a main component and a material containing a conductive filler as in the first embodiment. The second conductive adhesive layer 22B may be formed of an adhesive other than the urethane-based adhesive. However, when a urethane-based resin is used as a base material, the ends of the brush hairs are sufficiently bonded and the brush hairs are not easily removed. Since a charging belt can be obtained, the second conductive adhesive layer 22B is preferably an adhesive containing a urethane-based adhesive.
As described in the first embodiment, polyurethane adhesives such as polyisocyanate adhesives, prepolymer adhesives, and thermoplastic polymer adhesives are known as urethane adhesives. Any of these adhesives may be used. In the present embodiment, a urethane resin emulsion adhesive may be used. Urethane resin emulsion adhesives include, for example, an adhesive obtained by emulsifying a urethane resin in the presence of an emulsifier to emulsify, and an adhesive produced by emulsifying and dispersing simultaneously with a chain extension reaction of a urethane polymer. A urethane resin emulsion is more preferable from the viewpoint that the brush hair is difficult to come off. More specifically, for example, an adhesive containing 40% by mass of a urethane resin emulsion is used. (Here, the content is a numerical value when the total of the adhesive and the conductive filler is 100 parts by mass.)

  The conductive filler contained in the second conductive adhesive layer 22B is the same as that in the first embodiment and the first conductive adhesive layer 22A, and the content thereof is also the same.

  The thickness of the first conductive adhesive layer 22A is preferably 100 to 250 μm, more preferably 150 to 200 μm in a dry state. If it is such thickness, while ensuring a softness | flexibility, sufficient intensity | strength can be maintained to hold | maintain the edge part of a bristle.

  The charging belt of the image forming apparatus according to the second embodiment can be obtained by substantially the same manufacturing method as in the first embodiment. However, the process of providing a conductive adhesive layer on the release member 23, etc. as in the first embodiment. Is different. Hereinafter, description of the same process as 1st Embodiment is abbreviate | omitted, and a process different from 1st Embodiment is demonstrated.

First, the first conductive adhesive layer 22A is provided on the release member 23. The method for providing the first conductive adhesive layer 22A is not particularly limited as in the “providing the conductive adhesive layer 22” step of the first embodiment. Similar to the first embodiment, for example, it is provided by coating by a screen printing method or an inkjet method. The material and thickness are as described above.
Here, the adhesive of the first conductive adhesive layer 22A is preferably dried after application. Drying is preferably performed until a film is formed on the surface.

  Next, after drying (curing) the conductive adhesive for the first conductive adhesive layer, the second conductive adhesive layer 22B is provided on the first conductive adhesive layer 22A. The method is the same as that of the first conductive adhesive layer 22A. The material and thickness are as described above.

  Next, electrostatic flocking is performed on the fibers that become the brush hairs in the second conductive adhesive layer 22B. The electrostatic flocking is performed on the second conductive adhesive layer 22B. When electrostatic flocking is performed in the same manner as in the first embodiment, the adhesive layer of the first conductive adhesive layer 22A is cured, and as a result, the fibers are electrostatically flocked to the second conductive adhesive layer 22B.

  The process after electrostatic flocking is the same as in the first embodiment. That is, the first conductive adhesive layer 22 </ b> A and the second conductive adhesive layer 22 </ b> B in which brush hair fibers are electrostatically implanted are released from the release member 23. Thereby, the charging belt of the second embodiment is obtained.

  The charging belt 20 obtained by such a process has substantially the same characteristics as the first embodiment. However, according to this embodiment, the conductive adhesive layer is formed of two layers. The conductive adhesive layer is excellent in both adhesiveness to the release member and adhesiveness to the brush. That is, the conductive adhesive layer of the charging belt 20 is excellent in adhesiveness, easily forms a layer on the release member, and brush hair is not easily removed.

Note that the charging belt 20 of the second embodiment is also used while being tensioned by a pair of rollers 26 and 27 as in the first embodiment. That is, the relationship between the charging belt 20 and the rollers 26 and 27 in the second embodiment and the relationship between these and the photosensitive drum 10 are the same as those in the first embodiment.
Here, in the second embodiment, the nip width between the charging belt 20 and the photosensitive drum 10 is preferably in the range of 5 to 100 mm, and more preferably in the range of 10 to 20 mm.

  As mentioned above, although embodiment of this invention was described, these are only illustrations, and structures other than said description are employable. For example, in the first and second embodiments, an example in which the tension is applied to the charging belt by a pair of rollers has been described. For example, a configuration in which another roller is provided and tension is applied by three rollers is employed. May be. In this case, two of the three rollers form a pair, and the surface of the charging belt between the pair of rollers contacts the photosensitive drum in a surface contact state.

Example 1
As a cylindrical member, a stainless steel plate (metal plate) rolled into a cylindrical shape with a diameter of 60 mm (joined at both ends) is prepared, and this cylindrical member has a thickness of 0.3 mm and a cylindrical silicon rubber material. A cylindrical member surface covered with a mold member (manufactured by Tigers Polymer Co., Ltd.), a urethane emulsion adhesive (manufactured by DIC: trade name HYDRAN, product number HW-311) and a filler (carbon black Fuji). A conductive adhesive with the addition of trade name SPBLACK, product number 8338) was applied. The conductive adhesive was prepared by adding 500 grams of adhesive at a ratio of 250 grams of filler, and this conductive adhesive was applied by spraying so as to have a film thickness of 150 μm (hereinafter, Examples and Comparative Examples). The thickness of the adhesive layer refers to the thickness of the dried layer). As a result, one conductive adhesive layer was produced, and electrostatic flocking was carried out on the produced conductive adhesive layer so that the fibers shown in Table 1 satisfy the fiber conditions shown in the same table. Next, the electrostatically-planted conductive adhesive layer (one layer) is released from the release member, and the obtained cylindrical belt is installed on the roller of Embodiment 1 to form the image of Example 1. A device was made. (The image forming apparatus was assembled by setting the charging device obtained in the existing color laser printer (Oki Data Corporation, product number: B431dn). Examples 2 to 8 and Comparative Examples 1 to 8 are similarly described below. The image forming apparatus was assembled.)

(Example 2)
A belt composed of two conductive adhesive layers was also produced instead of the one conductive adhesive layer, and an image forming apparatus produced with this belt was designated as Example 2. The conductive adhesive layer of Example 2 is composed of an acrylic emulsion adhesive (manufactured by DIC: trade name Bonecoat product number S5) and a conductive adhesive obtained by adding a filler (carbon black manufactured by Fuji Dye Co., Ltd .: trade name: SPBLACK, product number 8338). The first adhesive layer (adhesive layer 1 shown in Table 1) is prepared by applying and drying the agent, and a urethane emulsion adhesive (manufactured by DIC: trade name Hydran, product number HW-311) is filled on the surface thereof. A conductive adhesive added with (carbon black manufactured by Fuji Dye Co., Ltd .: trade name SPBLACK, product number 8338) was applied to produce a second adhesive layer (adhesive layer 2 shown in Table 1). The conductive adhesive of the first adhesive layer was prepared by adding 500 grams of adhesive at a ratio of 250 grams of filler, and this conductive adhesive was applied by a spray method so as to have a film thickness of 50 μm. The conductive adhesive of the second adhesive layer is prepared by adding filler to the adhesive in the same proportion as the first adhesive layer, and this conductive adhesive is applied in the same manner as the first adhesive layer, 1 A second adhesive layer having a thickness of 150 μm was produced on the surface of the adhesive layer.

(Comparative Example 1)
Further, an image forming apparatus using the belt manufactured by the method for manufacturing a tubular flocked product such as a lens hood for a camera described above was used as Comparative Example 1. In detail, a molding cylinder having the same diameter as in Examples 1 and 2 was prepared using cardboard, and a polyethylene release film (manufactured by Nitto Denko Corporation: product number No. 440) having a thickness of 0.1 mm was wound around, and the surface was liquid. A hot melt (manufactured by Toagosei Co., Ltd .: trade name Aron Melt PPET, product number 1401SG) is applied to prepare an adhesive layer with a film thickness of 150 μm, and the fibers shown in Table 1 in the prepared adhesive layer have the fiber conditions shown in the same table. As such, electrostatic flocking was performed. Next, the electrostatic flocked adhesive layer was released from the release film to obtain a belt of Comparative Example 1. In the same manner as in Examples 1 and 2, the obtained cylindrical belt was installed on the roller of Embodiment 1 to produce an image forming apparatus.

(Comparative Example 2)
Furthermore, as a comparative example, a belt having a base film (base material) was also produced, and an image forming apparatus using the belt having the base film was defined as comparative example 2. The belt of Comparative Example 2 has a film thickness of 150 μm made of a conductive adhesive (same conductive adhesive as in Example 1) obtained by adding a filler to a base film having a rectangular shape of 32 × 230 mm, a material polyester, and a thickness of 0.1 mm. Then, electrostatically flocked the fibers shown in Table 1 to the applied conductive adhesive layer so as to satisfy the fiber conditions shown in the same table, and then the base film on which the fibers were electrostatically flocked And both ends thereof were joined to prepare a cylindrical belt having a base film. In Comparative Example 2, similarly to Examples 1 and 2, the obtained cylindrical belt was mounted on the roller of Embodiment 1 to produce an image forming apparatus (the cross-sectional shape is shown in FIG. 3).

(Examples 3 and 4 and Comparative Examples 3 and 4)
Regarding Examples 1 and 2 and Comparative Examples 1 and 2, the fiber length of the fibers to be electrostatically implanted was changed to further produce Examples and Comparative Examples. Specifically, the fiber length was changed from 1.0 mm to 1.5 mm, and Examples 3 and 4 corresponding to Examples 1 and 2 and Comparative Examples 3 and 4 corresponding to Comparative Examples 1 and 2 were respectively produced. (Other raw materials and conditions are the same as in Examples 1 and 2 and Comparative Examples 1 and 2, respectively).

(Examples 5 and 6 and Comparative Examples 5 and 6)
Moreover, the resistance value (electrical resistance value) of the fiber to be electrostatically implanted was changed, and examples and comparative examples were further produced. Specifically, the resistance value of the fiber is changed from 10 ⁴ to 10 ⁵ Ω · cm to 10 ⁵ to 10 ⁶ Ω · cm, and Examples 5 and 6 corresponding to Examples 1 and 2 and Comparative Examples 1 and 2 are changed. Corresponding Comparative Examples 5 and 6 were respectively produced (other raw materials and conditions were the same as in Examples 1 and 2 and Comparative Examples 1 and 2, respectively).

(Examples 7 and 8 and Comparative Examples 7 and 8)
Furthermore, the Example and comparative example which changed both the fiber length and the resistance value (electrical resistance value) of the fiber which carries out electrostatic flocking were also produced. Specifically, the fiber condition is changed from “fiber length 1.0 mm, resistance value 10 ⁴ to 10 ⁵ Ω · cm” to “fiber length 1.5 mm, resistance value 10 ⁵ to 10 ⁶ Ω · cm”. Examples 7 and 8 corresponding to Examples 1 and 2 and Comparative Examples 7 and 8 corresponding to Comparative Examples 1 and 2 were produced, respectively (the other raw materials and conditions were the same as in Examples 1 and 2 and Comparative Example 1, respectively. , 2).

Next, for the image forming apparatuses according to these examples and comparative examples, a print test for evaluating printed images was performed. Specifically, halftone images were printed, and image quality, particularly image spots, was visually evaluated on a five-point scale. The best one here was taken as 5. The deterioration of the charging brush with the passage of time is caused by the contamination of the brush belt, so that the difference is less likely to appear. Therefore, here, the evaluation was made based only on the quality of the initial image. The charging brush was evaluated in the case of (ii) rotating in the width direction with respect to the rotating direction of the member to be charged (photosensitive member) (peripheral speed is 1.1 times the peripheral speed of the photosensitive member).
The results are shown in Table 1. Table 1 is a table showing the conditions of the examples and comparative examples and the results of the print test. In Table 1, “brush streaks” and “black spots” indicate the types of image spots, and “total” indicates overall judgment regarding these image spots.

  Table 2 shows the evaluation criteria for “brush streaks” and “black spots” in Table 1. The scores of “brush streaks” and “black spots” 1 to 5 in Table 1 were determined according to the evaluation criteria shown in Table 2.

  Referring to Table 1, it can be seen that image spots are less likely to occur in Examples 1 and 2 than in Comparative Examples 1 and 2, and the quality of the printed image is higher. Further, referring to Table 1, it can be seen that the image quality of Comparative Example 2 is higher than that of Comparative Example 1. This result is considered due to the smoothness and flexibility of the surface shape of the belt. That is, the belt of Comparative Example 1 was confirmed to have a level difference on the surface due to the seam of the molding cylinder (the joint of the cardboard joints). No such step was confirmed, and the surface was smooth. It is considered that the difference in surface shape causes a difference in the uniformity of charging by the charging device, resulting in a difference in the printed images. Further, Comparative Example 2 is less flexible than Comparative Example 1 and Examples 1 and 2, and is not sufficiently flexible. Therefore, the nip width between the photosensitive drum and the belt is reduced, and as a result, the printed image is printed. It is thought that there was a difference in

  In general, the occurrence of image spots depends on the fiber length and the resistance value of the fiber, and the above results were the same even when the fiber length and the resistance value of the fiber were changed (Examples 3 to 8 in Table 1). And Comparative Examples 3 to 8). From this result, it was confirmed that the uniformity of charging by the charging device is caused by the smoothness and flexibility of the surface shape of the belt, and as a result, the printed image is different.

  From the results shown in Table 1, it can be seen that Examples 1 and 2 can form a good image even if the number of members (base film) is reduced, and can be reduced in cost compared to Comparative Example 2. In the case of Examples 1 and 2, since there is no electrical resistance element called a base film, the charging device can be designed more easily than Comparative Example 2. (This also applies to Examples 3 to 8)

DESCRIPTION OF SYMBOLS 10 Photosensitive drum 20 Charging belt 21 Brush layer 22 Conductive adhesive layer 22A 1st conductive adhesive layer 22B 2nd conductive adhesive layer 23 Release member 24 Cylindrical member 30 Exposure apparatus 40 Developing apparatus 50 Transfer brush 60 Cleaning apparatus 7 Conveyor belt 101 Fiber layer (brush layer)
102 Conductive adhesive (adhesive layer)
105 Base film (base material)

Claims (5)

An image carrier on which an electrostatic latent image is formed, and a charging device for charging the image carrier,
The charging device is an endless charging belt having endless flexibility in which fibers are electrostatically implanted in a conductive adhesive layer;
The endless charging belt is
After the release member having elasticity and the conductive adhesive layer are sequentially provided on the outer surface of the cylindrical base material, the fibers are electrostatically flocked to the conductive adhesive layer,
Further, the belt is obtained by releasing the conductive adhesive layer in which the fibers are electrostatically implanted from the release member, and is in contact with the image carrier in a surface contact state. An image forming apparatus for charging the image carrier. The endless charging belt is
After the release member having elasticity, the first adhesive layer and the second adhesive layer are sequentially provided on the outer surface of the cylindrical base material, fibers are electrostatically flocked to the second adhesive layer,
Furthermore, the belt obtained by releasing the first adhesive layer and the second adhesive layer in which the fibers are electrostatically flocked from the release member,
The first adhesive layer is a conductive adhesive layer containing an acrylic or rubber adhesive,
The image forming apparatus according to claim 1, wherein the second adhesive layer is a conductive adhesive layer including a urethane-based adhesive. The endless charging belt is installed in a state where tension is applied by at least a pair of rotating shafts;
The pair of rotating shafts is
The image forming apparatus according to claim 1, wherein a surface portion between the pair of rotating shafts of the endless charging belt is provided so as to contact the image carrier in a surface contact state.   The image forming apparatus according to claim 1, wherein the release member is made of a rubber-based resin layer. An image carrier on which an electrostatic latent image is formed, and a charging device for charging the image carrier,
The charging device is a method of manufacturing an image forming apparatus having an endless flexible endless charging belt in which fibers are electrostatically implanted in a conductive adhesive layer,
A step of sequentially providing a release member having elasticity and a conductive adhesive layer on the outer surface of the cylindrical substrate;
Electrostatically flocking the fibers to the conductive adhesive layer;
And a step of releasing the conductive adhesive layer in which the fibers are electrostatically flocked from the release member, and an image forming apparatus manufacturing method for obtaining an endless charging belt by the step.

Images