JP2016161908A - Charging brush, charging unit, toner cartridge, developing device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging brush that can optimize functions according to an installation place and an installation condition, a charging unit, a toner cartridge, a developing device, and an image forming apparatus.SOLUTION: A charging brush 10 of the present invention is a sheet-like brush that charges the surface of a latent image carrier used in an electrophotographic process, and comprises a base material 11, an adhesive layer 12 provided on the base material 11, and a brush part 14 formed of a plurality of brush bristles 13 implanted on the adhesive layer 12; the brush part 14 is provided such that the electric resistance value of the brush bristles 13 is reduced from the upstream side toward the downstream side in a direction of rotation of the latent image carrier.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a charging brush, a charging unit, a toner cartridge, a developing device, and an image display device that can be applied to, for example, an electrophotographic image forming apparatus.

  In general, in an image forming apparatus employing an electrophotographic system, a charging brush or the like is provided in order to uniformly charge the surface of a latent image carrier. A charging brush is known (see Patent Document 1 below). In recent years, the size of image forming apparatuses has been reduced, and accordingly, the size of charging brushes has been desired to be reduced. However, in the case of a roll-type charging brush, it is difficult to save space by downsizing, and in the case of a rubber-roll charging brush, a cleaner member is also required. Therefore, in the conventional roll-shaped charging brush, the installation location and the installation conditions are limited, but it is difficult to exert the required charging brush performance without being affected by the installation location. ing.

  As a conventional charging brush, a sheet-like charging brush is also known. As a sheet-like charging brush, for example, there is a charging brush in which pile yarns are woven into a base fabric by W weaving, and fibers constituting the pile yarns are spread and brushed to form brush hairs (Patent Document 2 below). . However, even with a sheet-like charging brush, it is difficult to exert the required charging brush performance regardless of the installation location and installation conditions.

JP-A-8-101559 JP-A-5-173402

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a charging brush, a charging unit, a toner cartridge, and a developing device capable of optimizing functions according to an installation location and installation conditions. An apparatus and an image forming apparatus are provided.

  In order to solve the above problems, the charging brush of the present invention is a sheet-like charging brush for charging the surface of a latent image carrier used in an electrophotographic process, and is provided on a base material and the base material. And an electric resistance value of the brush bristles in the brush portion changes continuously or stepwise in a plane. It is characterized by that.

  According to the above configuration, since the electric resistance value of the brush hair in the brush portion is changed continuously or stepwise in the surface, the function can be optimized according to the installation location and conditions. Can be provided.

  For example, in a region where the electrical resistance value is increased, it is possible to improve the performance of collecting and storing untransferred residual toner attached to the surface of the latent image carrier, external additives to the toner, and the like. On the other hand, in the region where the electrical resistance value is reduced, the performance of charge injection with respect to the remaining toner or the like can be improved.

  Further, the charging brush of the present invention is in the form of a sheet, can be provided in accordance with the surface of the latent image carrier, and there is no restriction on the installation location, so that space saving can be achieved compared to a roll-shaped charging brush. . Furthermore, since the charging brush of the present invention has a configuration in which a plurality of brush hairs are planted in the adhesive layer on the base material, the brush that is brought into contact with the surface of the latent image carrier even if the length of the brush hair is shortened. The hair density is not substantially reduced. As a result, the cleaning performance and charging performance can be maintained even when the length of the bristle is shortened as compared with, for example, a charging brush having a pile woven fabric structure. Thereby, further space saving becomes possible.

  In the brush portion, it is preferable that the electrical resistance value of the brush hair in the upstream region in the rotation direction of the latent image carrier is smaller than the electrical resistance value of the brush hair in the downstream region. By reducing the electric resistance value of the brush bristles in the region on the upstream side in the rotation direction of the latent image carrier, it is possible to improve the charge injection performance for the residual toner and the external additive in the region. Here, the residual toner into which the electric charge has been injected has the same charge polarity as that of the brush portion, so that the amount of the residual toner etc. attached can be suppressed in the downstream area. As a result, reduction in charging performance of the brush portion can be prevented.

  In the brush portion, it is preferable that the electric resistance value of the brush hair in the upstream area in the rotation direction of the latent image carrier is larger than the electric resistance value of the brush hair in the downstream area. By increasing the electric resistance value of the brush bristles in the region upstream of the rotation direction of the latent image carrier, it is possible to improve the performance of collecting and storing residual toner and external additives in the region. The cleaning function can be improved. As a result, the cleanliness of the latent image carrier is improved, and contamination of the region on the downstream side of the brush portion can be reduced.

  In the above configuration, a pressing member that presses the base material is provided below the base material, and the pressing member varies the pressing force in the plane to the base material. The pressing force applied to the latent image carrier by the brush bristles is preferably changed continuously or stepwise in the plane. In the above configuration, a pressing member is provided below the base material to apply a pressing force, whereby the bristles are configured to press against the latent image carrier. In addition, since the pressing force of the pressing member is varied continuously or stepwise in the plane with respect to the base material, the pressing of the brush hair against the latent image carrier is also varied continuously or stepwise in the plane. be able to. As a result, the function of the brush part can be varied in the plane.

  For example, in a region where the pressing force of the pressing member is increased and the pressing force of the brush hair against the latent image carrier is increased, untransferred residual toner adhering to the surface of the latent image carrier or external addition to the toner The function of scraping and removing the agent, that is, the cleaning function can be improved. In addition, the charge injection performance for the remaining toner can be improved. On the other hand, in a region where the pressing force by the pressing member is reduced and the pressing force of the brush hair against the latent image carrier is reduced, the performance of collecting and storing the residual toner and the external additive can be improved.

  In addition, in a low humidity environment, brush bristles tend to concentrate an electric field from the tip of the hair, which may cause abnormal discharge. As a result, there is a problem that white spots and white stripes are generated on the image. However, in the above-described configuration, the bristles are pressed by the elastic member and come into pressure contact with the latent image carrier, so that the tips of the bristles can be brought into contact with the surface of the latent image carrier. As a result, the occurrence of abnormal discharge can be reduced and the occurrence of white spots or white stripes in the printed image can be suppressed.

  In the above-described configuration, the pressing member includes a first elastic member that presses the brush bristles in an upstream region in the rotation direction of the latent image carrier in the brush portion against the latent image carrier, and the brush. And a second elastic member that presses the brush bristles in the downstream area in the rotation direction of the latent image carrier in the portion, and the brush bristles in the upstream area by the first elastic member. It is preferable that the pressing force to the brush is smaller than the pressing force to the brush bristles in the downstream area by the second elastic member. According to the above configuration, in the upstream area, the pressing force of the brush hair against the latent image carrier is lower than the pressing force of the brush hair on the latent image carrier in the downstream area. The performance of collecting and storing the residual toner and the external additive in the toner can be further improved, and contamination due to the residual toner and the like in the downstream region can be further reduced. Further, since the mechanical stress on the latent image carrier in the upstream region can be reduced, the life of the latent image carrier can be extended.

  In the above configuration, the height of the bristles is substantially uniform, the first elastic member and the second elastic member are made of the same sponge-like material extending in the longitudinal direction, and the first elastic member The height of the member is preferably lower than the height of the second elastic member. Thereby, the pressing force by the first elastic member can be made smaller than the pressing force by the second elastic member.

  In order to solve the above-described problems, a charging unit of the present invention is a charging unit including the above-described charging brush and is detachably provided in a toner cartridge, a developing device, or an image forming apparatus. .

  In order to solve the above-described problems, a toner cartridge according to the present invention is a toner cartridge that is integrally provided with the above-described charging brush and is detachably provided in an image forming apparatus.

  In order to solve the above-described problems, a developing device of the present invention is a developing device that is integrally provided with the above-described charging brush and is detachably provided in an image forming apparatus.

  In order to solve the above problems, an image forming apparatus of the present invention includes the above-described charging unit, the above-described toner cartridge, or the above-described developing device.

The present invention has the following effects by the configuration described above.
That is, according to the charging brush of the present invention, since the electric resistance value of the brush hair in the brush portion is changed continuously or stepwise in the surface, the function of the brush portion can be varied in the surface. Therefore, it is possible to provide a charging brush capable of optimizing functions according to the installation location and conditions.

  Further, since the charging brush of the present invention is in the form of a sheet, for example, space saving and size reduction can be achieved as compared with a roll-shaped charging brush. In addition, since the plurality of brush hairs are implanted in the adhesive layer on the base material, the density of the brush hairs brought into contact with the latent image carrier surface is substantially reduced even if the length of the brush hairs is shortened. There is no decline. Furthermore, the cleaning performance and the charging performance can be maintained even if the length of the bristle is shortened as compared with the sheet-like charging brush having a pile woven fabric structure. As a result, it is possible to provide a charging brush, a charging unit, a toner cartridge, a developing device, and an image forming apparatus that can further reduce space and size.

1 is a perspective view schematically illustrating a charging brush according to an embodiment of the present invention. FIG. 2A is a side view showing the charging brush, and FIG. 2B is a graph showing a distribution of electrical resistance values of the bristle of the charging brush. FIG. 3A is a side view showing another charging brush according to the present embodiment, and FIG. 3B is a graph showing a distribution of electrical resistance values of the bristle of the charging brush. FIG. 4A is a side view showing a charging brush according to another embodiment, and FIG. 4B is a graph showing a distribution of electrical resistance values in the bristles of the charging brush. It is a perspective view which represents typically the aspect in the case of mounting the charging brush which concerns on other embodiment of this invention in an image forming apparatus. FIG. 2 is a front view schematically showing the structure of an image forming unit in an image forming apparatus provided with the charging brush, where FIG. 1A shows a case where the charging brush is connected to a developing device, and FIG. ) Represents a case where the charging brush is connected to a toner cartridge provided in the developing device.

(Embodiment 1)
The charging brush according to the present embodiment will be described below with reference to FIG. FIG. 1 is a perspective view schematically showing a charging brush according to an embodiment of the present invention. FIG. 2A is a side view showing the charging brush as viewed from the longitudinal direction, and FIG. 2B is a graph showing a distribution of electrical resistance values in the bristles of the charging brush. FIG. 3A is a side view showing another charging brush according to the present embodiment as viewed from the longitudinal direction, and FIG. 3B is a graph showing a distribution of electric resistance values on the bristles of the charging brush.

  As shown in FIG. 1, the charging brush 10 of the present embodiment includes an adhesive layer 12 provided on a base material 11, and a brush portion 14 in which a plurality of brush hairs 13 are planted on the adhesive layer 12. It is a sheet-like brush provided with.

  Since the charging brush 10 has a sheet shape, the area where the brush bristles 13 come into contact with a latent image carrier to be described later can be increased as compared with a conventional roll-shaped charging brush. Therefore, the cleaning function and the charging function of the charging brush 10 of the present embodiment can be improved. The length of the charging brush 10 in the longitudinal direction is not particularly limited, and can be appropriately set according to the size of the latent image carrier. Further, the width of the charging brush 10 in the short direction is set according to the contact area where the brush hairs 13 are desired to contact the surface of the latent image carrier. Usually, it is preferably within a range of 5 mm to 100 mm, more preferably within a range of 10 mm to 50 mm, and particularly preferably within a range of 20 mm to 30 mm.

  The substrate 11 is not particularly limited, and examples thereof include polypropylene, ABS (acrylonitrile-butadiene-styrene) resin, polystyrene, polyethylene, melamine resin, phenol resin, silicone resin, nylon resin and other polyamide resins, polybutylene terephthalate, Examples thereof include polyphenylene ether, polyphenylene sulfide, polyethersulfone, polycarbonate, polyimide, polyamideimide, polyetherimide, polysulfone, polyetheretherketone, polyethylene terephthalate, polyarylate, metal and the like.

  The length in the longitudinal direction and the width in the short direction of the substrate 11 can be appropriately set according to the size of the latent image carrier, the charging brush 10 and the like. Moreover, although the thickness of the base material 11 is not specifically limited, Usually, it exists in the range of 10 micrometers-300 micrometers, Preferably it is 30 micrometers-200 micrometers, More preferably, they are 50 micrometers-150 micrometers.

  The constituent material of the adhesive layer 12 is not particularly limited. For example, the adhesive layer 12 is composed of an adhesive mainly composed of acrylic resin, vinyl acetate, polyurethane, synthetic rubber, natural rubber, or the like.

  Further, the adhesive layer 12 may contain an arbitrary conductive material for imparting conductivity to the adhesive layer 12 to form a conductive adhesive layer. It does not specifically limit as said electroconductive material, For example, electroconductive powder, such as a metal and carbon (carbon), is mentioned. Furthermore, the conductive powder of the metal is not particularly limited. For example, a powder of a noble metal such as Ag, Pt, or Au, a metal such as Cu, Ni, Fe, Cr, Co, Al, Sb, or Mo, or these An alloy or an oxide powder may be used. The conductive carbon powder is not particularly limited, and examples thereof include carbon black, carbon fiber, and graphite particles. These conductive materials may be used alone or in combination of two or more. In addition, it does not specifically limit as an addition amount in the case of adding an electroconductive material to the adhesive bond layer 12, It can set suitably as needed.

  The thickness of the adhesive layer 12 is not particularly limited, and is usually in the range of 50 μm to 600 μm, preferably 100 μm to 500 μm, more preferably 150 μm to 300 μm. By setting the thickness of the adhesive layer 12 to 50 μm or more, good shape stability of the charging brush 10 can be achieved. Moreover, when the thickness of the adhesive layer 12 is set to 600 μm or less, when the bristles 13 are planted, so-called bleeding of the adhesive can be prevented. If the thickness of the adhesive layer 12 is too large, when the brush bristles 13 are implanted in the adhesive layer 12, the adhesive in the planted part rises due to capillary action, and the adhesive layer in the peripheral area of the planted part May become thinner. However, by setting the thickness of the adhesive layer 12 to 600 μm or less, it is possible to prevent the brushed hair 13 from seeping up and the adhesive layer is formed after the applied adhesive is dried. It is possible to prevent the occurrence of no part.

  As shown in FIGS. 2 (a) and 2 (b), the brush portion 14 has a continuous electric resistance value of the brush bristles 13 from the upstream side to the downstream side in the rotation direction of the latent image carrier described later. It is provided to be smaller. By increasing the electrical resistance value of the brush bristles 13 in the upstream region, the performance of collecting and storing residual toner in the region can be improved, and the cleaning function is improved. As a result, the cleanliness of the latent image carrier can be maintained. In addition, the contamination of the downstream region of the charging brush 10 can be reduced, and the reduction in charging performance can be suppressed.

  However, the present invention is not limited to this embodiment. For example, an embodiment in which the electric resistance value of the brush bristles 13 continuously increases as it goes from the upstream side to the downstream side in the rotation direction of the latent image carrier. It may be. In this case, the charge injection performance for the remaining toner and the like can be improved in the upstream region, so that the remaining toner and the like can be charged uniformly and effectively. Since the charge polarity of the charged residual toner and the charge polarity of the charging brush are the same, the adhesion amount of the residual toner or the like on the brush hair can be reduced in the downstream region. As a result, also in this aspect, reduction in charging performance can be suppressed.

  Furthermore, the present invention can adopt a mode in which the electric resistance value of the brush bristles 13 gradually decreases as shown in FIGS. 3 (a) and 3 (b). The first region 14a, the second region 14b, and the third region 14c shown in the figure are provided so as to extend in the longitudinal direction of the charging brush and be parallel to each other. Furthermore, although the first area 14a, the second area 14b, and the third area 14c have the same area, the present invention is not limited to this, and the areas of the respective areas may be varied as necessary. Good.

  As a method of changing the electrical resistance value of the brush hair 13 in the brush portion 14 in the plane, in addition to the method of sequentially planting the brush hairs 13 having different electrical resistance values in the adhesive layer 12, for example, the brush hair 13 It is also possible to vary the electric resistance value of the adhesive layer 12 in which the hair is implanted. Specifically, an adhesive layer with a small amount of conductive material added is provided on the upstream side in the rotation direction of the latent image carrier, and an adhesive layer with a large amount of conductive material is sequentially formed toward the downstream side. The method of doing is mentioned. Further, in order to charge the surface of the latent image carrier to a predetermined potential, when applying a DC voltage, an AC voltage, or a superimposed voltage composed of a DC voltage and an AC voltage to the charging brush 10, a position to apply these voltages. The electrical resistance value of the brush bristles 13 can be changed in the plane also by changing. Specifically, in the charging brush 10, by applying a voltage to the leading end of the sheet positioned downstream in the rotation direction of the latent image carrier, the electrical resistance value of the brush bristles 13 is changed to the rotation direction of the latent image carrier. The size can be reduced from the upstream side to the downstream side.

  The brush hair 13 is not particularly limited as long as it has conductivity. The method for imparting conductivity is not particularly limited, and examples thereof include a method in which conductive particles are dispersed and contained in a synthetic fiber. The synthetic fibers are not particularly limited, and examples thereof include polyamide fibers such as nylon (registered trademark) fibers and aramid fibers, polyester fibers such as polyethylene terephthalate fibers and polyarylate fibers, acrylic fibers such as polyacrylonitrile fibers, polyethylene fibers, and polypropylene. Examples thereof include synthetic fibers such as polyolefin fibers such as fibers and fluorine fibers such as polytetrafluoroethylene fibers. Also included are regenerated fibers such as rayon fibers and cupra fibers, and semi-synthetic fibers such as cellulose acetate fibers such as acetate fibers and triacetate fibers. Furthermore, natural fibers, such as hemp, cotton, wool, etc. are also mentioned. Further, the brush bristles 13 may be used alone or in combination of at least two of the synthetic fibers, regenerated fibers, semi-synthetic fibers or natural fibers exemplified above. From the viewpoint of easy availability and easy performance imparted to various applications, it is preferable to use at least one selected from the synthetic fibers, specifically, nylon (registered trademark) resin, etc. Is mentioned. The conductive particles are not particularly limited, and examples thereof include tin oxide, titanium oxide, molybdenum silicide, tungsten carbide, carbon black, carbon short fibers, and graphite particles.

  Further, as another method for imparting conductivity, for example, a method of adhering the conductive particles to the surface of the synthetic fiber or the like via an adhesive can be mentioned. In this case, the adhesive is not particularly limited, and examples thereof include an adhesive mainly composed of acrylic resin, polyvinyl acetate, polyurethane, synthetic rubber, natural rubber, and the like. Moreover, the method etc. which provide the polymer resin layer in which the said electroconductive particle was disperse | distributed on the surface of the said synthetic fiber etc. are mentioned. In this case, examples of the polymer resin layer include those containing the adhesive as a main component. Furthermore, the method of providing a metal plating layer in at least one part of surfaces, such as the said synthetic fiber, is mentioned. In this case, the metal plating layer is not particularly limited, and examples thereof include a copper plating layer, a nickel plating layer, a gold plating layer, and a silver plating layer.

  In the case of the above-described embodiment using conductive particles, the electrical resistance value can be controlled by changing the blending amount of the conductive particles. Moreover, in the case of the said aspect using a metal plating layer, control of an electrical resistance value is possible by changing the kind, thickness, etc. of the material which comprises the said metal plating layer.

Flocking density of the brush bristles 13 is preferably from 5,000 to 30,000 present / cm ^2, and more preferably 7,000 to 20,000 present / cm ^2. By setting the flocking density to 5,000 / cm ² or more, it is possible to secure a cleaning function for the brush portion 14 to collect residual toner and the like. In addition, by setting the flocking density to 30,000 / cm ² or less, it is easy to discharge residual toner from the charging brush 10, and the charging brush 10 can be easily refreshed. As a result, the durability of the charging brush 10 can be improved.

  The length of the brush bristles 13 is not particularly limited, and can be appropriately set in consideration of the nip width with the latent image carrier. However, since the charging brush 10 has a configuration in which a plurality of brush hairs 13 are planted in the adhesive layer 12 on the base material 11, for example, the length of the brush hair 13 is longer than that of a charging brush having a pile woven fabric structure. Even if the length is shortened, the density of the bristles 13 brought into contact with the surface of the latent image carrier is not substantially lowered. Even if the length of the brush bristles 13 is shortened and the nip width is reduced, the cleaning performance and charging performance of the charging brush 10 can be maintained. As a result, further space saving can be achieved. The length of the brush bristles 13 is preferably within the range of 0.1 mm to 5 mm, more preferably within the range of 0.5 mm to 3 mm, from the root portion that is normally planted in the adhesive layer 12. Moreover, the thickness (diameter, fiber diameter) of the said bristle 13 is not specifically limited, According to a use etc., it can set suitably. For example, the diameter of the brush bristles 13 is preferably about 5 μm to 100 μm, and more preferably 10 μm to 70 μm.

  The cross-sectional shape of the brush bristles 13 in a plan view is not particularly limited, and examples thereof include a circular shape, an elliptical shape, and a polygonal shape with rounded corners.

  The brush bristles 13 may be planted in a straight hair state so as to be perpendicular to the adhesive layer 12, or may be planted in a slanted state so as to incline at an arbitrary angle. When the hair bristles 13 are planted in a slanted state, the number of bristles with the hair tips facing the latent image carrier can be reduced, thereby making it possible to suppress the occurrence of abnormal discharge. Become.

  A method for manufacturing the charging brush 10 is not particularly limited, and a known method can be adopted. Specifically, first, an adhesive is applied onto the substrate 11 to form an adhesive application layer. Next, the bristles 13 are implanted in the adhesive application layer. The method of flocking is not particularly limited, and examples thereof include electrostatic flocking and mechanical flocking found in toothbrushes. In the case of electrostatic flocking, for example, a high DC voltage is applied between a pair of flat electrodes, and the brush hairs 13 are placed on one electrode to be charged. The substrate 11 is grounded between a pair of electrodes and is electrically grounded. Thereby, the bristle 13 is made to fly along the direction of the electric lines of force in the electric field generated between the electrodes, and the bristle 13 is planted in an upright state on the adhesive coating layer. Thereafter, the adhesive application layer is dried under arbitrary drying conditions to form the adhesive layer 12. Furthermore, the method for changing the electrical resistance value of the brush bristles 13 in the brush section 14 in the plane is as described above. Thereby, the charging brush 10 of this Embodiment can be produced.

(Embodiment 2)
The charging brush according to the second embodiment will be described below with reference to FIG. FIG. 4A is a side view showing a charging brush according to another embodiment as viewed from the longitudinal direction, and FIG. 4B is a graph showing a distribution of electric resistance values on the bristles of the charging brush.

  As shown in FIG. 4A, the brush portion 19 of the charging brush 20 is adjacent to the first charging area 19a located on the upstream side in the rotation direction of the latent image carrier and the first charging area 19a. It comprises a second charging area 19b located downstream in the rotation direction of the image carrier. The bristles 13 in the first charging area 19a have a smaller electrical resistance value than the bristles 13 in the second charging area 19b. However, the electric resistance values of the brush bristles 13 in the first charging area 19a and the second charging area 19b are substantially uniform in the respective areas.

  The first charging area 19a and the second charging area 19b are provided so as to extend in the longitudinal direction of the charging brush 10 and to be parallel to each other. The first charging area 19a and the second charging area 19b have the same area. However, the present invention is not limited to this, and the areas of the first charging area 19a and the second charging area 19b may be made different as appropriate. For example, the cleaning function of the charging brush 10 is improved by making the first charging area 19a wider than the second charging area 19b, or charging is performed by making the second charging area 19b wider than the first charging area 19a. The function may be improved.

  A first elastic member 16 for pressing the bristles 13 corresponding to the first charging regions 19a against the latent image carrier is provided on the surface of the base 11 opposite to the surface on which the adhesive layer 12 is provided. Is provided. A second elastic member for pressing the bristles 13 corresponding to the second charging region 19b against the latent image carrier on the surface opposite to the surface on which the adhesive layer 12 of the substrate 11 is provided. 17 is provided.

  As shown in FIG. 4A, the first elastic member 16 and the second elastic member 17 are fixedly provided on the support member 15. The first elastic member 16 corresponds to the first charging area 19 a of the brush portion 19, and the second elastic member 17 corresponds to the second charging area 19 b of the brush portion 19. The method for fixing the first elastic member 16 and the second elastic member 17 to the support member 15 is not particularly limited, and for example, the above-described adhesive layer can be used. Furthermore, the end portion in the longitudinal direction of the support member 15 is folded back in the opposite direction and connected to the end portion in the longitudinal direction on the upstream side of the base material 11. It does not specifically limit as a connection method, For example, it can connect to an adhesive agent etc.

  The first elastic member 16 and the second elastic member 17 are provided apart from each other. Thereby, the effect of the elasticity and height of the member can be clarified. However, the present invention is not limited to this mode, and the first elastic member 16 and the second elastic member 17 may be disposed in regions corresponding to the first charging region 19a and the second charging region 19b, respectively. Good. Moreover, both may be adjacent. Thereby, further space saving can be achieved. Further, the first elastic member 16 and the second elastic member 17 are provided so as to be parallel to each other.

  Since the first charging area 19a is pressed by the first elastic member 16 having a pressing force smaller than that of the second elastic member 17, the remaining toner in the first charging area and the external additive to the toner are collected. The housing performance can be further improved, and contamination due to residual toner or the like in the second charged region can be further reduced. Further, since the pressing force by the first elastic member 16 is small, the mechanical stress on the latent image carrier can also be reduced and the life can be extended.

  In addition, by providing the first elastic member 16 and the second elastic member 17, the first elastic member 16 and the second elastic member 17 correspond to areas corresponding to the respective areas (that is, the first charging area 19a and the second charging area 19b). ) Of the bristles 13 are pressed, so that the tips of the bristles 13 can be inclined and brought into contact with the surface of the latent image carrier. Thereby, even in a low humidity environment, it is possible to reduce the occurrence of abnormal discharge due to the concentration of the electric field from the hair tip. As a result, it is possible to suppress the occurrence of white spots or white stripes on the image due to abnormal discharge. The abnormal discharge described in the present embodiment is different from the discharge according to the normal Paschen's law, and the discharge stop voltage is lower than that according to the Paschen's law. It means a phenomenon that causes such discharge.

  The first elastic member 16 and the second elastic member 17 are made of the same sponge-like material having a rectangular parallelepiped shape. The widths of the first elastic member 16 and the second elastic member 17 in the short direction are substantially the same, and are appropriately set according to the width of the charging brush 20 and the widths of the first charging area 19a and the second charging area 19b. The On the other hand, the height of the first elastic member 16 is set to be lower than the height of the second elastic member 17. Thereby, the pressing force by the first elastic member 16 can be made smaller than the pressing force by the second elastic member 17. Note that the shape of the sponge-like material is not particularly limited, and may be a cylindrical shape or the like. Moreover, although the shape and material of the 1st elastic member 16 and the 2nd elastic member 17 are the same, they may differ. The 1st elastic member 16 and the 2nd elastic member 17 are not limited to what consists of sponge-like materials, You may use what consists of elastic bodies, such as rubber | gum and a synthetic resin. Furthermore, although the height of the 1st elastic member 16 and the 2nd elastic member 17 is based also on the elastic force which each has, Preferably it exists in the range of 1 mm-10 mm, More preferably, it exists in the range of 2 mm-8 mm. Especially preferably, it is in the range of 4 mm to 7 mm.

  The upper surfaces of the first elastic member 16 and the second elastic member 17 are not fixed to the surface of the end portion 18a opposite to the side on which the adhesive layer 12 is provided, and are free ends. This is because the height of the first elastic member 16 is lower than that of the second elastic member 17. By making the height of the first elastic member 16 lower than that of the second elastic member 17, the pressing force with which the bristle 13 in the first charging area 19 a presses the latent image carrier is changed to the brush bristle in the second charging area 19 b. 13 can be made smaller than the pressing force for pressing the latent image carrier. In the base material 18, a member (not shown) for pressing the brush portion 19 is provided on the surface opposite to the surface on which the first elastic member 16 and the second elastic member 17 are provided. ing.

  It does not specifically limit as the supporting member 15, The thing which consists of the same material as the above-mentioned base material 11 and a different material can be used.

  Furthermore, when the charging brush of the present embodiment is provided in the image forming apparatus, for example, it is possible to provide it with a configuration as shown in FIG. FIG. 5 is a perspective view illustrating a schematic configuration of the charging brush 20.

  In the charging brush 20 shown in the figure, an end 18a in the longitudinal direction of the substrate 18 is folded back in the opposite direction by a folded portion 18b, and the brush portion 14 is provided on the end 18a via the adhesive layer 12. ing. The adhesive layer 12 may be provided on the entire surface of the base material 18, but is preferably formed only on the end portion 18 a of the base material 18. Further, the first elastic member 16 and the second elastic member 17 are fixedly provided so as to extend in the longitudinal direction on the base material 18 positioned below the end portion 18a folded in the opposite direction. Yes.

  The method for manufacturing the charging brush 20 is not particularly limited, and the charging brush 20 can be manufactured by the same method as that for the charging brush 10 of the first embodiment.

  As the base material 18, a material made of the same material as the above-described base material 11 or a material made of a different material can be used, but it is more preferable to use a material made of an elastic material such as rubber or synthetic resin. This is because the base material 18 becomes a foundation for flocking the bristles 13.

Here, when the charging brush 20 of the present embodiment is applied to an electrophotographic image forming apparatus, it can be used as follows.
FIG. 6 is a front view schematically showing the structure of the image forming unit in the image forming apparatus provided with the charging brush 20, and FIG. 6A shows the case where the charging brush 20 is connected to the developing device. FIG. 4B shows a case where the charging brush 20 is connected to a toner cartridge provided in the developing device. The image forming apparatus outputs data read by a scanner included in the image forming apparatus or data from an external device (for example, an image processing apparatus such as a personal computer) connected to the image forming apparatus as an image. Is.

  As shown in FIG. 6A, the image forming unit 40 includes a photosensitive drum 21 as a latent image carrier, a charging brush 20, an exposure device 22, a developing device 23, a transfer roll 24, and a conveyance belt. 25 and a charging control device 26. Around the photosensitive drum 21, along the rotation direction indicated by the arrows in FIG. 4A, there are a charging brush 20, an exposure device 22, a developing device 23, a transfer roll 24, a transport belt 25, and a charging control device 26. The configuration is arranged in order.

  The photosensitive drum 21 serves as an electrostatic latent image carrier and a photosensitive member in the image forming apparatus, and has a cylindrical shape.

  The exposure device 22 exposes the surface of the photosensitive drum 21 charged by the charging brush 20 with a laser beam or the like based on data from an image processing device such as a personal computer, for example, so that the surface of the photosensitive drum 21 is statically exposed. This is for forming an electrostatic latent image. As the exposure device 22, for example, a semiconductor laser or a light emitting diode can be used.

  The developing device 23 supplies toner to the surface of the photosensitive drum 21, and develops and develops the electrostatic latent image formed on the surface of the photosensitive drum 21 as a toner image. In the developing device 23, toner is supplied to the developing roll 23 b with a constant thickness from a toner supply roll 23 a provided in the housing 23 c, and the developing roll 23 b comes into contact with the photosensitive drum 21, thereby causing the photosensitive drum 21. Toner is supplied to the surface of the toner.

  The conveyance belt 25 conveys the recording medium 27 to the photosensitive drum 21 after the toner image is formed on the surface of the photosensitive drum 21.

  The transfer roll 24 is for transferring the toner image on the surface of the photosensitive drum 21 to the recording medium 27 that is a transfer material, and transports the sheet metal in parallel with the surface direction of the recording medium 27. The belt 25 is disposed so as to face the photosensitive drum 21 with the belt 25 interposed therebetween. Note that the recording medium 27 is, for example, paper, OHP, or the like. The transfer roll 24 is made of, for example, a urethane rubber roll.

  The charge control device 26 controls the charge of the remaining positive and negative toners remaining on the photosensitive drum 21 after transfer, for example, so as to be all negative. The charging controller 26 can be omitted.

  The charging brush 20 is provided so as to be connected to the developing device 23 with the bristles 13 of the brush portion 19 in contact with the surface of the photosensitive drum 21. More specifically, the base 18 in the charging brush 20 is provided integrally connected to the housing 23c of the developing device 23. However, since the charging brush 20 can be manufactured at low cost, the charging brush 20 may be configured as a charging unit that is detachable from the developing device 23. Further, the charging brush 20 may be configured to be integrated with the housing 23c. In this case, the developing device 23 itself can be detachable from the image forming apparatus.

  In the present embodiment, since the charging brush 20 includes the first charging area 19a having a function of collecting residual toner and the like, so-called untransferred toner particles remaining on the surface of the photosensitive drum 21 and the toner are removed. There is no need to separately provide a cleaning member for removing additives and the like. Therefore, it is possible to reduce the mechanical stress on the latent image bearing member and to extend the life, and also to deteriorate the sensitivity due to image defects and abrasion due to scratching the photosensitive drum 21, the deterioration of charging property, and the image due to charge leakage. It is also possible to reduce abnormal images such as density reduction and background contamination. Further, since the installation of the cleaning member is unnecessary, the electrophotographic process can be executed by a cleaner-less method.

  Here, the cleanerless system includes, for example, a scattering passing type, a temporary capturing type, and a combined type. However, the charging brush 20 of the present embodiment can be applied to any method. In the case of the scattering passing type, the brush toner 13 of the first charging area 19a is used as a scattering member to scratch the residual toner on the photosensitive drum 21, thereby reducing the adhesive force between the residual toner and the photosensitive drum 21. Thereafter, in the developing region where the developing roll 23b and the photosensitive drum 21 face each other, residual toner or the like on the photosensitive drum 21 is electrostatically transferred to the developing roll 23b to be collected in the developing device 23. it can.

  In the case of the temporary capture type, the brush bristles 13 in the first charging area 19a temporarily capture residual toner and the like on the photosensitive drum 21 as a capture member. Then, after the end of the print job or at the inter-sheet timing between print jobs, the captured residual toner or the like is discharged and retransferred to the photosensitive drum 21, and then electrostatically transferred to the developing roll 23 b to develop the developing device 23. Collect in. In the above-mentioned scattering passing type, when a large amount of residual toner is generated, for example, when a solid image is formed or after a jam occurs, there is a possibility that the image may be deteriorated by exceeding the collection ability to the developing device 23. However, when the charging brush 20 of the present embodiment is applied to the temporary capturing type, the residual toner or the like captured by the brush hair in the first charging area 19a is gradually collected in the developing device 23, thereby causing image degradation. Can be suppressed.

  In the combined type, the scattered passing type and the temporary capture type are used in combination. Specifically, the functions of the scattering member and the capturing member are used in combination with the brush bristles 13 of the first charging region 19a. In other words, by applying only a DC voltage to the first charging area 19a, the brush bristles 13 in the first charging area 19a function as a scattering member, while switching the bias from a DC voltage to a superimposed voltage as necessary. The bristles 13 of the first charging area 19a are caused to function as a capturing member.

  Further, as shown in FIG. 6B, the charging brush 20 of the present embodiment may be provided integrally with a toner cartridge 43 that is detachably provided on the cartridge mounting portion of the developing device 23. In this case, the charging brush 20 may be configured as a charging unit that is detachable from the toner cartridge 43.

(Other matters)
In the second embodiment, the case where the first elastic member 16 as the pressing member is made to correspond to the first charging region 19a and the second elastic member 17 is made to correspond to the second charging region 19b has been described as an example. The present invention is not limited to this embodiment.
For example, a mode in which the second elastic member 17 is made to correspond to the first charging area 19a and the first elastic member 16 is made to correspond to the second charging area 19b can be adopted. In this case, since the first charging region 19a is pressed by the second elastic member 17 having a pressing force larger than that of the first elastic member 16, it adheres to the surface of the latent image carrier. A cleaning function for removing the remaining toner and the like, and a charge injection function for the remaining toner and the like are also provided. As a result, the contamination of the second charged region 19b can be further reduced.

DESCRIPTION OF SYMBOLS 10, 20 Charge brush 11 Base material 12 Adhesive layer 13 Brush bristle 14 Brush part 16 1st elastic member 17 2nd elastic member 18 Base material 18a End part 18b Folding part 19 Brush part 19a 1st charging area 19b 2nd charging area 21 Photosensitive drum (latent image carrier)
22 Exposure Device 23 Developing Device 23a Toner Supply Roll 23b Developing Roll 23c Housing 24 Transfer Roll 25 Conveying Belt 26 Charging Control Device 27 Recording Medium 40 Image Forming Unit 43 Toner Cartridge

Claims (10)

A sheet-like charging brush for charging the surface of a latent image carrier used in an electrophotographic process,
A substrate;
An adhesive layer provided on the substrate;
A brush portion comprising a plurality of brush hairs planted in the adhesive layer,
The charging brush in which the electric resistance value of the bristle in the brush portion changes continuously or stepwise in a plane.   2. The charging brush according to claim 1, wherein, in the brush portion, the electric resistance value of the brush bristle in the upstream region in the rotation direction of the latent image carrier is smaller than the electric resistance value of the brush bristle in the downstream region.   2. The charging brush according to claim 1, wherein, in the brush portion, the electric resistance value of the bristle in the upstream region in the rotation direction of the latent image carrier is larger than the electric resistance value of the bristle in the downstream region. A pressing member that presses the base material is provided below the base material,
The pressing member changes the pressing force to the latent image carrier by the brush bristles continuously or stepwise in the surface by changing the pressing force in the surface to the base material. The charging brush according to any one of claims 1 to 3. The pressing member is
A first elastic member for causing the latent image carrier to press the bristles in the upstream region in the rotation direction of the latent image carrier in the brush portion;
The brush portion comprises a second elastic member that presses the brush bristles in a region downstream of the latent image carrier in the rotation direction of the latent image carrier,
5. The charging brush according to claim 4, wherein a pressing force of the first elastic member to the brush hair in the upstream region is smaller than a pressing force of the second elastic member to the brush hair in the downstream region. The height of the brush bristles is substantially uniform,
The charging brush according to claim 5, wherein the first elastic member and the second elastic member are made of the same sponge-like material extending in the longitudinal direction, and the height of the first elastic member is lower than the height of the second elastic member. .   A charging unit comprising the charging brush according to claim 1, wherein the charging unit is detachably provided in a toner cartridge, a developing device, or an image forming apparatus.   A toner cartridge integrally including the charging brush according to claim 1, wherein the toner cartridge is detachably provided in the image forming apparatus.   A developing device integrally comprising the charging brush according to claim 1, wherein the developing device is detachably provided on the image forming apparatus. An image forming apparatus comprising the charging unit according to claim 7, the toner cartridge according to claim 8, or the developing device according to claim 9.

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