JP4016868B2 - Developing roll and electrophotographic apparatus using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a copying machine, the present invention relates to an electrophotographic apparatus using the developing roll and it is used in an electrophotographic apparatus such as a printer.
[0002]
[Prior art]
In the non-contact developing type electrophotographic apparatus, since the developing roll and the photosensitive drum are not in contact with each other, it is easy to increase the developing speed and to cope with high speed copying. During the development, toner is caused to fly from the surface of the developing roll to the surface of the photosensitive drum. For this reason, in order to obtain the uniformity of the image, it is necessary to make the flying property of the toner uniform. For that purpose, the gap between the developing roll and the photosensitive drum (the surface and the surface of both in the toner flying portion) is required. Is required to be uniform along the axial direction.
[0003]
However, since the layer forming blade and the toner supply roll are usually in pressure contact with the developing roll, the developing roll B is bent as shown in FIG. 4, and the gap G with the photosensitive drum D is narrow at the center. It gradually spreads toward both ends. In FIG. 4, the layer forming blade and the toner supply roll are not shown. Thus, the bending of the developing roll B is a factor that causes the gap G to vary in the axial direction.
[0004]
By the way, the applicant of the present application has proposed and already filed a magnetic developing roll that makes the gap G uniform along the axial direction (see, for example, Patent Document 1). As shown in FIG. 5, the magnetic developing roll C has a cylindrical resin sleeve 12 provided coaxially and rotatably on the outer periphery of a rod-shaped magnet 11 while maintaining a certain space. Although the layer forming blade S is in pressure contact with the outer peripheral surface, the toner supply roll is not in pressure contact (no toner supply roll is required). Then, by forming the resin sleeve 12 into a continuous shape gradually decreasing in diameter from both end portions toward the center portion, the resin sleeve 12 is bent by the pressure contact with the layer forming blade S, The gap G (see FIG. 4) is set to be uniform along the axial direction.
[0005]
[Patent Document 1]
Japanese Utility Model Publication No. 2-89455 [0006]
[Problems to be solved by the invention]
However, since the layer forming blade S is in pressure contact with the magnetic developing roll C of Patent Document 1 above, but the toner supply roll is not in pressure contact, the deflection of the magnetic developing roll C is a force (layer) becomes deflection due to pressure contact force F _S) from the forming blade S, magnetic developer of large leaves and deflection becomes which was (flexed state from the virtual plane P containing the axes of rotation and the photosensitive drum D of the magnetic developing roller C indicated by broken lines C ₁ a central portion of the roll C in FIG. 5). For this reason, the uniformity of the gap G is still insufficient and there is room for improvement.
[0007]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a developing roll capable of improving the uniformity of the gap with the photosensitive drum and an electrophotographic apparatus using the developing roll.
[0008]
[Means for Solving the Problems]
To achieve the above object, the present onset Ming, a core metal, and a base rubber layer formed on the outer peripheral surface of the metal core, is formed directly or via another layer on the outer circumferential surface of the base rubber layer The outermost layer of the outermost layer is arranged in a non-contact state with respect to the outer circumferential surface of the photosensitive drum , and is vertically moved by a virtual plane including the rotating shaft of the photosensitive drum and the rotating shaft of the photosensitive drum. A developing roll in which the layer forming blade is in pressure contact in one of the divided spaces and the toner supply roll is in pressure contact in the other space, and the base rubber layer gradually decreases in diameter from both axial ends toward the center. The developing roll in which the outermost layer is formed to have a constant thickness and the outermost layer is formed to have a constant thickness, and the outer peripheral surface of the outermost layer itself is not in contact with the outer peripheral surface of the photosensitive drum. A developing roll arranged in a state, and the photosensitive drum A layer forming blade that presses against the developing roll in one space that is vertically divided into two by an imaginary plane that includes the rotation axis and the rotation axis of the roller, and a toner supply roll that presses against the developing roll in the other space. An electrophotographic apparatus comprising the photosensitive drum, wherein the developing roll is the developing roll according to the first aspect, and the distance between the outermost layer of the developing roll and the photosensitive drum is in the axial direction. It shall be the electrophotographic apparatus a second aspect which is uniform along.
[0009]
In the developing roll of the present invention, the outer peripheral surface of the outermost layer is formed in a continuous shape with a gradually decreasing diameter from both end portions toward the central portion, so that it is pressed and bent by the layer forming blade and the toner supply roll. However, the gap between the developing roll and the photosensitive drum can be made uniform along the axial direction. That is, in the present invention, the pressure contact positions by the layer forming blade and the toner supply roll are located in respective spaces that are divided into two vertically by a virtual plane including the rotation axis of the developing roll itself and the rotation axis of the photosensitive drum. It is like that. For this reason, the components perpendicular to the imaginary plane of the pressure contact forces act in directions (opposite directions) that cancel each other. As a result, the bending due to the two pressure contacts is a bending close to the virtual plane or a bending along the virtual plane as compared with a state where the toner supply roll is not pressed (in the case of a conventional magnetic developing roll). . Therefore, the uniformity of the gap is improved to such an extent that it can sufficiently cope with the high functionality of the electrophotographic apparatus. In addition, the developing roll of the present invention can make the gap uniform along the axial direction even if it is bent, so that it is not necessary to increase the diameter of the core metal or make it hollow to prevent the bending. For this reason, a solid core with a reduced diameter can be used as the core metal. Therefore, since it becomes possible to use a commercially available small-diameter cored bar as it is or almost without processing, cost can be reduced.
[0010]
In addition, the above-mentioned “stitched shape” includes not only the shape that starts from both ends, but also the outer diameter is constant in the axial direction within a certain range at both the left and right ends, and from the left and right ends to the center. Among those in which the spelling shape starts and those in the whole spelling shape, those whose outer diameter is constant in the axial direction only within a certain range of the central portion are included.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings.
[0012]
FIG. 1 shows an embodiment of the developing roll of the present invention. The developing roll A is composed of a core metal 1, a base rubber layer 2 formed on the outer peripheral surface of the core metal 1, and a surface layer (outermost layer) 3 formed on the outer peripheral surface of the base rubber layer 2. The outer peripheral surface of the base rubber layer 2 is formed in a continuous shape gradually decreasing in diameter from both end portions toward the central portion, and the surface layer 3 is formed with a constant thickness. Further, as shown in FIG. 2, the developing roll A is used in a non-contact developing type electrophotographic apparatus, and is arranged in a non-contact state with the photosensitive drum D. The layer forming blade S and the toner supply roll T are in pressure contact with the developing roll A. The layer forming blade S and the toner supply roll T rotate between the rotating shaft of the developing roll A and the photosensitive drum D. It is positioned in each space that is divided into two vertically by a virtual plane P including an axis. The gap between the developing roll A and the photosensitive drum D even if the developing roll A is bent by the pressing force F _S by the layer forming blade _S and the pressing force F _T by the toner supply roll T due to the collapsing shape of the developing roll A. G can be made uniform along the axial direction.
[0013]
That is, the above-described spelling shape is appropriately set according to the pressure contact conditions (the pressure contact forces F _{S and} F _T , the pressure contact position and the pressure contact direction) by the layer forming blade S and the toner supply roll T. As the setting method, for example, in the developing roll A, first, the shape of the outer peripheral surface of the base rubber layer 2 is a straight shape aligned with the outer diameters of both ends, and the surface layer 3 is formed with a constant thickness on the outer peripheral surface. A rolled body is prepared, and pressure contact similar to the pressure contact conditions of the layer forming blade S and the toner supply roll T is applied to the roll body. Next, the roll body bent by the press contact is rotated, and in the rotated state, a virtual photosensitive drum D with respect to the layer forming blade S and the toner supply roll T is assumed, and the outer periphery of the roll body in the rotated state is assumed. Of the surface, the portion facing the virtual photosensitive drum D (toner flying portion) is polished in parallel with the rotational axis of the photosensitive drum D so that the gap G with the photosensitive drum D is uniform along the axial direction. . And after grinding | polishing is complete | finished, when the pressure-contact with respect to the said roll body is cancelled | released and the said roll body is returned to the original state, the outer peripheral surface of the surface layer 3 will become a continuous shape. In this way, a desired spelling shape can be set.
[0014]
The developing roll A can be produced, for example, as follows. That is, first, the inner peripheral surface of the cylindrical mold is formed in accordance with the stitch shape set as described above. Next, the core metal 1 is coaxially installed in the hollow portion of the cylindrical mold, and the gap between the core metal 1 and the cylindrical mold is filled with the material for forming the base rubber layer 2. Vulcanization is performed by oven vulcanization or the like, and the above-described base rubber layer 2 is formed on the outer peripheral surface of the cored bar 1. Then, after removing the mold, the surface layer 3 is applied to the outer peripheral surface of the base rubber layer 2 by a roll coating method at a constant thickness, and then dried or heat-treated to form the surface layer 3. In this way, the developing roll A can be produced.
[0015]
When the developing roll A obtained in this way is incorporated into an actual machine, as shown in FIG. 3, the layer forming blade S (see FIG. 2) and the toner supply roll T (see FIG. 2) are pressed and bent. The gap G with the drum D becomes uniform along the axial direction. That is, as shown in FIG. 2, each of the press contact positions is located in each space divided into two by a virtual plane P including the rotation axis of the developing roll A itself and the rotation axis of the photosensitive drum D. The components perpendicular to the imaginary plane P of the pressure contact forces F _{S and} F _T act in directions (reverse directions) that cancel each other. For this reason, the bending due to the two pressure contact forces F _{S and} F _{T is} a bending in the state of approaching the virtual plane P or a bending along the virtual plane P (the central portion of the developing roll A in the bent state is illustrated. shown by broken lines a ₁ to 2). Therefore, the gap G between the developing roll A and the photosensitive drum D becomes uniform in the axial direction, and can sufficiently cope with the high functionality of the actual machine.
[0016]
As described above, even when the developing roll A is bent, the gap G can be made uniform along the axial direction. Therefore, it is not necessary to increase the diameter of the core metal 1 or to make it hollow to prevent the bending. For this reason, a solid commercial product with a reduced diameter (outside diameter of about 8 to 10 mm) can be used as the core metal 1, and the cost can be reduced by the amount that processing such as welding is unnecessary.
[0017]
More specifically, the material of the metal core 1 is not particularly limited, and examples thereof include iron, iron plated, stainless steel, and aluminum. Moreover, you may apply | coat an adhesive agent, a primer, etc. to the surface of the said metal core 1 as needed. Further, the adhesive, primer, etc. may be made conductive as necessary.
[0018]
The material for forming the base rubber layer 2 is not particularly limited. For example, silicone rubber, ethylene-propylene-diene rubber (EPDM), styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber ( IR), acrylonitrile-butadiene rubber (NBR), polyurethane elastomer and the like. Among these, it is preferable to use silicone rubber from the viewpoint of low hardness and less sag.
[0019]
A crosslinking agent, a vulcanizing agent, a foaming agent, a plasticizer, a softening agent, a tackifier, a release agent, a conductive agent, and the like may be appropriately added to the forming material of the base rubber layer 2 as necessary. .
[0020]
As a material for forming the surface layer 3, the following main material containing a conductive agent is used. That is, the main material is not particularly limited. For example, hydrogenated acrylonitrile-butadiene rubber (hydrogenated nitrile rubber: H-NBR), acrylonitrile-butadiene rubber (nitrile rubber: NBR), polyurethane-based elastomer, Chloroprene rubber (CR), natural rubber, butadiene rubber (BR), acrylic rubber (ACM), isoprene rubber (IR), styrene-butadiene rubber (SBR), hydrin rubber (ECO, CO), urethane rubber, fluorine rubber, etc. It is done. Among these, H-NBR is particularly preferable from the viewpoint of adhesiveness and coating solution stability.
[0021]
Examples of the conductive agent include an ionic conductive agent and an electronic conductive agent, and these are preferably used in combination because the surface potential of the surface layer 3 can be easily uniformed. Examples of the ionic conductive agent include quaternary ammonium compounds such as trimethyloctadecyl ammonium chloride, and perchlorates, benzoates, nitrites, sulfates, and hydrochlorides of these quaternary ammonium compounds. Examples of the electronic conductive agent include carbon black, graphite, potassium titanate, iron oxide, c-TiO ₂ , c-ZnO, and c-SnO ₂ . In addition, the above “c−” means having conductivity.
[0022]
In addition to the conductive agent, the material for forming the surface layer 3 includes a stabilizer, an ultraviolet absorber, an antistatic agent, a reinforcing agent, a charge control agent, a lubricant, a release agent, a dye, a pigment, a flame retardant, and oil. You may add suitably as needed.
[0023]
In the above embodiment, the case, between the base Sugomu layer 2 and the surface layer 3, an intermediate layer may be formed. As the material for forming the intermediate layer, the same material as that for the surface layer 3 can be used.
[0024]
Next, examples will be described together with comparative examples.
[0025]
[Example 1]
As a developing roll, a base rubber layer having a continuous shape was formed on the outer peripheral surface of the core metal, and a surface layer having a constant thickness (0.03 mm) was formed on the outer peripheral surface of the base rubber layer. The axial length of the base rubber layer and the surface layer was 240 mm. The outer diameter of the surface layer is set to 16.00 mm at both ends, 15.97 mm from the center of both ends to 15.97 mm, and 120 mm from the both ends (center) to 15.96 mm. A spelled shape was formed. As the core metal, a solid iron column having a diameter of 10 mm was used.
[0026]
[Preparation of base rubber layer forming material]
Conductive silicone rubber (KE1357 A / B, manufactured by Shin-Etsu Chemical Co., Ltd.) was kneaded using a kneader to prepare a base rubber layer forming material (compound).
[0027]
[Preparation of surface layer forming material]
100 parts of H-NBR (Zetpol 0020, manufactured by Nippon Zeon Co., Ltd.), 0.01 part of γ-mercaptopropyltrimethoxysilane (A189, manufactured by Nippon Unicar Co., Ltd.), 0.5 part of stearic acid, and zinc white (ZnO) ) 5 parts, 30 parts of ketjen black, 0.5 part of vulcanization accelerator (tetramethylthiuram disulfide), 1 part of vulcanization accelerator (ortho-tolyl-biguanidine), and vulcanizing agent (sulfur) 0 5 parts were mixed and dispersed to prepare a surface layer forming material (coating solution).
[0028]
[Comparative Example 1]
As the developing roll, a straight roll whose outer diameter (16.00 mm) was constant in the axial direction was produced. The cored bar has a hollow structure, and the outer diameter is increased to 14 mm to prevent bending. This metal core was produced by resistance-welding shaft end members to both ends of a cylindrical member having an outer diameter of 14 mm and a thickness of 1 mm. Other than that, it was the same as in Example 1 above.
[0029]
The costs of the developing rolls of Example 1 and Comparative Example 1 thus obtained were compared as follows. Each of the developing rolls was incorporated into a laser beam printer (manufactured by Epson, LP-3000), the layer forming blade and the toner supply roll were brought into pressure contact, and the deflection was measured.
[0030]
〔Cost Comparison〕
The developing roll of Example 1 did not require welding for the core metal, whereas the developing roll of Comparative Example 1 required welding for the core metal. And since the axial displacement occurred in the shaft end members at both ends due to the welding, the centering operation was performed. For this reason, the developing roll of Comparative Example 1 was more expensive than the developing roll of Example 1 in terms of welding and centering to the core metal.
[0031]
[Measure deflection]
In addition, the gap with the surface of the photosensitive drum was measured from one edge of the surface layer to the other edge along the axial direction in a state where each developing roll was incorporated in the copying machine. As a result, in the developing roll of Example 1, the gap was uniform along the axial direction, and the variation was 8 μm. On the other hand, in the developing roll of Comparative Example 1, the gap was large at both end portions and gradually decreased toward the center portion, and the variation was 100 μm.
[0032]
【The invention's effect】
As described above, according to the developing roll of the present invention, the outer peripheral surface is formed in a continuous shape with a gradually decreasing diameter from both end portions toward the central portion. Even if it is bent, the gap between the developing roll and the photosensitive drum can be made uniform along the axial direction. That is, the pressure contact positions by the layer forming blade and the toner supply roll are positioned in respective spaces that are divided into two vertically by a virtual plane including the rotation axis of the developing roll itself and the rotation axis of the photosensitive drum. For this reason, the components perpendicular to the virtual plane of each pressure contact force act in directions (opposite directions) that cancel each other, so that the gap between the developing roll and the photosensitive drum can be made uniform along the axial direction. It becomes possible. As a result, it becomes possible to sufficiently cope with the high functionality of the electrophotographic apparatus.
[0033]
Further, in the developing roller of the present invention, when the outermost layer on the conductive layer can be made uniform surface potential of the outermost layer, the flying of the toner can be stabilized. In addition, it is possible to expect an effect of preventing deflection or the like in the layer below the outermost layer, and it is possible to realize further improvement in the uniformity of the gap.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a developing roll of the present invention.
FIG. 2 is an explanatory view showing a state in which the developing roll is incorporated in an actual machine.
FIG. 3 is an explanatory view showing a state in which the developing roll is incorporated in an actual machine.
FIG. 4 is an explanatory view showing a state in which a conventional developing roll is incorporated in an actual machine.
FIG. 5 is an explanatory view showing a state in which a conventional magnetic developing roll is incorporated in an actual machine.
[Explanation of symbols]
A Development roll 1 Core 2 Base rubber 3 Surface layer

Claims (4)

A metal core, a base rubber layer formed on the outer peripheral surface of the metal core, and an outermost layer formed directly or via another layer on the outer peripheral surface of the base rubber layer, the outer periphery of the outermost layer The surface of the photosensitive drum is arranged in a non-contact state with respect to the outer peripheral surface of the photosensitive drum, and the layer forming blade is pressed into contact with one of the upper and lower spaces by a virtual plane including the rotational axis of the photosensitive drum and its own rotational axis. A developing roll in which the toner supply roll is in pressure contact with the other space, wherein the base rubber layer is formed in a continuous shape gradually decreasing in diameter from both axial end portions toward the central portion, and the outermost layer Is a developing roll having a constant thickness . The developing roll according to claim 1, wherein the outermost layer is a conductive layer. The developing roll according to claim 1, wherein an intermediate layer is formed between the base rubber layer and the outermost layer. The outermost surface of the outermost layer of itself is divided into two vertically by a virtual plane including a developing roll arranged in a non-contact state with respect to the outer peripheral surface of the photosensitive drum, and the rotating shaft of the photosensitive drum and the rotating shaft of the photosensitive drum. An electrophotographic apparatus comprising: a layer forming blade that is in pressure contact with the developing roll in one space; a toner supply roll that is in pressure contact with the developing roll in the other space; and the photosensitive drum. The developing roll according to any one of claims 1 to 3, wherein the distance between the outermost layer of the developing roll and the photosensitive drum is uniform along the axial direction. Photo equipment.

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