JP2020056950A - Developing device and image forming apparatus including the same - Google Patents

Abstract

To provide a developing device that can prevent a floating toner from being adhered by static electricity to a surface of a cover member on the opposite side of a casing, and an image forming apparatus including the same.SOLUTION: The developing devices 3a to 3d comprise: developing rollers 31 that supply toner to photoreceptor drums 1a to 1d; and developing containers 20 that accommodate the developing rollers 31. The developing containers 20 are each provided with a sheet-like cover member 50 covering at least part of the developing container 20. A top face 50a of the cover member 50 is applied with an anti-static agent, or the cover member 50 is formed of a conductive sheet.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a developing device and an image forming apparatus having the same, and more particularly, to a developing device having a developing roller for supplying toner to an image carrier and an image forming apparatus having the same.

  An electrophotographic image forming apparatus irradiates light based on image information read from a document image or image information transmitted from an external device such as a computer onto the peripheral surface of an image carrier (photosensitive drum). After forming an electrostatic latent image and supplying toner from the developing device to the electrostatic latent image to form a toner image, the toner image is transferred to paper. The sheet after the transfer process is discharged to the outside after the toner image is fixed.

  As an image forming apparatus using a two-component developer including a magnetic carrier and a toner, a developing roller disposed to face an image carrier, a magnetic roller (toner supply roller) for supplying toner to the developing roller, and a developer There is known an image forming apparatus including a stirring and conveying member for stirring and conveying, and a developing device for supplying only the toner from the magnetic roller to the developing roller after supplying the developer from the stirring and conveying member to the magnetic roller.

  In recent years, in an image forming apparatus, the configuration of the apparatus has become complicated with the progress of color printing and high-speed processing, and a high-speed rotation of a toner stirring member in a developing apparatus has been inevitable in order to cope with high-speed processing. . In particular, in a developing method using a two-component developer containing a magnetic carrier and a toner, and using a magnetic roller (toner supply roller) carrying the developer and a developing roller carrying only the toner, the developing roller, the magnetic roller, , Only the toner is carried on the developing roller by the magnetic brush formed on the magnetic roller, and the toner on the developing roller not used for development is peeled off and collected by the magnetic roller. For this reason, in the developing method using the developing roller and the magnetic roller, the amount of the floating toner is greatly increased.

  Therefore, for example, in Japanese Patent Application Laid-Open No. 2003-163, an image forming apparatus provided with a duct and a fan for sucking the floating toner in order to suppress the toner floating in the developing apparatus from scattering (leaking) outside the developing apparatus. Is disclosed.

JP 2011-197290 A

  However, even in the image forming apparatus provided with a duct and a fan for sucking the floating toner as in Patent Document 1, the toner floating in the developing device is scattered (leaked) outside the developing device. Cannot be completely prevented.

  Therefore, for example, when a cover member made of an insulating resin sheet is disposed so as to cover a part of the developing container, the floating toner adheres to the surface of the cover member opposite to the developing container due to static electricity. As a result, when the developing device is replaced, there is a problem that the hands and clothes of the worker become dirty, and the surroundings become dirty due to toner scattering.

  The present invention has been made in order to solve the above-described problem, and an object of the present invention is to suppress adhesion of floating toner due to static electricity to a surface of a cover member opposite to a casing. And an image forming apparatus including the same.

  In order to achieve the above object, a developing device according to a first configuration of the present invention is disposed so as to face an image carrier on which an electrostatic latent image is to be formed, and is provided on the image carrier in a region facing the image carrier. The image forming apparatus includes a developing roller that supplies the toner, and a casing that houses the developing roller. The casing is provided with a sheet-like cover member that covers at least a part of the casing. The first surface of the cover member opposite to the casing is coated with an antistatic agent, or the cover member is formed of a conductive sheet.

  According to the developing device of the first configuration of the present invention, the antistatic agent is applied to the first surface of the cover member opposite to the casing, or the cover member is formed of a conductive sheet. This can prevent the floating toner from adhering to the first surface of the cover member opposite to the casing due to static electricity. As a result, when replacing the developing device, it is possible to prevent the hands and clothes of the worker from being stained and the surroundings from being stained due to toner scattering.

FIG. 1 is a cross-sectional view schematically illustrating a structure of an image forming apparatus including a developing device according to an embodiment of the present disclosure. FIG. 1 is a side cross-sectional view illustrating a structure of a developing device according to an embodiment of the present invention. FIG. 2 is a perspective view illustrating a structure of a developing device, a toner suction path, and a toner collection container according to the exemplary embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a structure of a cover member of the developing device according to the embodiment of the present disclosure. It is sectional drawing which shows the structure of the cover member of the modification of one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  An image forming apparatus 100 according to an embodiment of the present invention will be described with reference to FIGS. In the main body of the image forming apparatus 100 (here, a color printer), four image forming units Pa, Pb, Pc and Pd are arranged in order from the upstream side in the transport direction (the right side in FIG. 1). These image forming portions Pa to Pd are provided corresponding to images of four different colors (cyan, magenta, yellow, and black), and are formed by charging, exposing, developing, and transferring, respectively, cyan, magenta, and yellow. And black images are sequentially formed.

  Photosensitive drums (image carriers) 1a, 1b, 1c, and 1d each carrying a visible image (toner image) of each color are disposed in these image forming units Pa to Pd. (Not shown), an intermediate transfer belt (intermediate transfer member) 8 rotating clockwise in FIG. 1 is provided adjacent to each of the image forming units Pa to Pd. The toner images formed on the photoconductor drums 1a to 1d are sequentially primary-transferred and superimposed on the intermediate transfer belt 8 moving while contacting the photoconductor drums 1a to 1d. Thereafter, the toner image primarily transferred onto the intermediate transfer belt 8 is secondarily transferred onto a transfer sheet P as an example of a recording medium by the operation of the secondary transfer roller 9. Further, the transfer paper P on which the toner image is secondarily transferred is discharged from the main body of the image forming apparatus 100 after the toner image is fixed in the fixing unit 13. While rotating the photosensitive drums 1a to 1d counterclockwise in FIG. 1, an image forming process is performed on each of the photosensitive drums 1a to 1d.

  The transfer paper P on which the toner image is secondarily transferred is accommodated in a paper cassette 16 arranged at a lower portion of the main body of the image forming apparatus 100, and is transferred via a paper feed roller 12a and a registration roller pair 12b. The intermediate transfer belt 8 is conveyed to a nip portion between the intermediate transfer belt 8 and a driving roller 11. As the intermediate transfer belt 8, a sheet made of a dielectric resin is used, and a seamless (seamless) belt is mainly used. Further, a blade-shaped belt cleaner 19 for removing toner and the like remaining on the surface of the intermediate transfer belt 8 is disposed downstream of the secondary transfer roller 9.

  Next, the image forming units Pa to Pd will be described. Chargers 2a, 2b, 2c, and 2d for charging the photosensitive drums 1a to 1d are provided around and below the rotatable photosensitive drums 1a to 1d, and image information is stored in each of the photosensitive drums 1a to 1d. Exposure device 5, developing devices 3a, 3b, 3c and 3d for forming toner images on photosensitive drums 1a to 1d, and removing the developer (toner) remaining on photosensitive drums 1a to 1d Cleaning sections 7a, 7b, 7c and 7d are provided.

  When image data is input from a host device such as a personal computer, first, the surfaces of the photosensitive drums 1a to 1d are uniformly charged by the chargers 2a to 2d, and then the light is irradiated by the exposure device 5 in accordance with the image data. Then, an electrostatic latent image corresponding to the image data is formed on each of the photosensitive drums 1a to 1d. Each of the developing devices 3a to 3d is filled with a predetermined amount of a two-component developer containing toner of each color of cyan, magenta, yellow and black. When the ratio of the toner in the two-component developer filled in each of the developing devices 3a to 3d falls below a specified value due to the formation of a toner image described later, each of the developing devices 3a to 3d The toner is supplied to the devices 3a to 3d. The toner in the developer is supplied onto the photoconductor drums 1a to 1d by the developing devices 3a to 3d, and adheres electrostatically, whereby the toner according to the electrostatic latent image formed by exposure from the exposure device 5 is formed. A toner image is formed.

  Then, an electric field is applied at a predetermined transfer voltage between the primary transfer rollers 6a to 6d and the photosensitive drums 1a to 1d by the primary transfer rollers 6a to 6d, and cyan, magenta, yellow and yellow on the photosensitive drums 1a to 1d are applied. The black toner image is primarily transferred onto the intermediate transfer belt 8. These four-color images are formed with a predetermined positional relationship predetermined for forming a predetermined full-color image. Thereafter, in preparation for the subsequent formation of a new electrostatic latent image, the toner and the like remaining on the surfaces of the photosensitive drums 1a to 1d after the primary transfer are removed by the cleaning units 7a to 7d.

  The intermediate transfer belt 8 is stretched around a driven roller 10 on the upstream side and a drive roller 11 on the downstream side, and the intermediate transfer belt 8 rotates clockwise with the rotation of the drive roller 11 by a drive motor (not shown). When the rotation starts, the transfer paper P is conveyed from the pair of registration rollers 12b to the nip portion (secondary transfer nip portion) between the drive roller 11 and the secondary transfer roller 9 provided adjacent thereto at a predetermined timing. Then, the full-color image on the intermediate transfer belt 8 is secondarily transferred onto the transfer paper P. The transfer paper P on which the toner image has been secondarily transferred is conveyed to the fixing unit 13.

  The transfer paper P conveyed to the fixing unit 13 is heated and pressed by the fixing roller pair 13a, so that the toner image is fixed on the surface of the transfer paper P, and a predetermined full-color image is formed. The transfer direction of the transfer paper P on which the full-color image has been formed is divided by the branch portion 14 branched in a plurality of directions, and the transfer paper P is directly sent (or after being sent to the double-sided conveyance path 18 and subjected to double-sided copying) by the discharge roller pair 15. The sheet is discharged to a discharge tray 17.

  Next, a detailed structure of the developing device 3a will be described with reference to FIG. Note that FIG. 2 shows a state viewed from the back side of the paper of FIG. 1, and the arrangement of each member in the developing device 3 a is reversed left and right from FIG. 1. In the following description, the developing device 3a arranged in the image forming unit Pa in FIG. 1 is exemplified, but the configuration of the developing devices 3b to 3d arranged in the image forming units Pb to Pd is basically the same. Therefore, the description is omitted.

  As shown in FIG. 2, the developing device 3a includes a developing container (casing) 20 in which a two-component developer (hereinafter, simply referred to as a developer) containing a magnetic carrier and a toner is stored. Is divided into a stirring and transporting chamber 21 and a supply and transporting chamber 22 by a partition wall 20a. The stirring and transporting chamber 21 and the supply and transporting chamber 22 are provided with a stirring and transporting screw 25a and a supply and transporting screw 25b for mixing and agitating and charging the toner supplied from the toner container 4a (see FIG. 1) with the magnetic carrier. It is arranged rotatably.

  The developer is conveyed in the axial direction (a direction perpendicular to the paper surface of FIG. 2) while being stirred by the stirring and conveying screw 25a and the supply and conveying screw 25b, and passes through a developer (not shown) formed at both ends of the partition wall 20a. It circulates between the agitation transfer chamber 21 and the supply transfer chamber 22 via a path. That is, a developer circulation path is formed in the developing container 20 by the agitation transfer chamber 21, the supply transfer chamber 22, and the developer passage.

  The developing container 20 extends obliquely to the upper right of FIG. 2, and a magnetic roller (toner supply roller) 30 is disposed above the supply / conveyance screw 25 b in the developing container 20 and obliquely to the upper right of the magnetic roller 30. Has a developing roller 31 opposed thereto. A part of the outer peripheral surface of the developing roller 31 is exposed from the opening 20b of the developing container 20, and faces the photosensitive drum 1a. The magnetic roller 30 and the developing roller 31 rotate counterclockwise in FIG.

  The magnetic roller 30 includes a nonmagnetic rotating sleeve that rotates counterclockwise in FIG. 2 and a fixed magnet body having a plurality of magnetic poles included in the rotating sleeve.

  The developing roller 31 includes a cylindrical developing sleeve that rotates counterclockwise in FIG. 2 and a developing roller-side magnetic pole fixed inside the developing sleeve. The magnetic roller 30 and the developing roller 31 face each other. They face each other with a predetermined gap at the position. The developing roller-side magnetic pole has a polarity different from that of the opposite magnetic pole of the fixed magnet body.

  A regulating blade 35 is attached to the developing container 20 along the longitudinal direction of the magnetic roller 30 (perpendicular to the plane of FIG. 2). With respect to the clockwise direction), it is positioned upstream of the facing region R between the developing roller 31 and the magnetic roller 30. A slight gap is formed between the tip of the regulating blade 35 and the surface of the magnetic roller 30.

  A DC voltage (hereinafter also referred to as Vslv (DC)) and an AC voltage (hereinafter also referred to as Vslv (AC)) are applied to the developing roller 31, and a DC voltage (hereinafter referred to as Vmag (DC)) is applied to the magnetic roller 30. ) And an AC voltage (hereinafter, also referred to as Vmag (AC)). These DC voltage and AC voltage are applied to each sleeve of the developing roller 31 and the magnetic roller 30 from a developing bias power supply via a bias control circuit (both not shown).

  As described above, while the developer is being stirred by the stirring and conveying screw 25a and the supply and conveying screw 25b, the toner is circulated through the stirring and conveying chamber 21 and the supply and conveying chamber 22 in the developing container 20, and the toner is charged. The developer is transported to the magnetic roller 30. Then, a magnetic brush (not shown) is formed from the developer on the magnetic roller 30, and after the thickness of the magnetic brush on the magnetic roller 30 is regulated by the regulating blade 35, the magnetic brush 30 faces the developing roller 31. A thin toner layer is formed on the developing roller 31 by the electric field difference ΔV between Vmag (DC) applied to the magnetic roller 30 and Vslv (DC) applied to the developing roller 31 and the magnetic field.

  The thickness of the toner layer on the developing roller 31 varies depending on the resistance of the developer, the difference in the rotation speed between the magnetic roller 30 and the developing roller 31, and the like. However, the thickness is controlled by the potential difference ΔV between the magnetic roller 30 and the developing roller 31. Can be. When the potential difference ΔV is increased, the toner layer on the developing roller 31 becomes thicker, and when the potential difference ΔV is reduced, the toner layer becomes thinner.

  The toner thin layer formed on the developing roller 31 by the magnetic brush is conveyed to a region (developing region) where the photosensitive drum 1 a and the developing roller 31 are opposed to each other by the rotation of the developing roller 31. Since a predetermined bias (Vslv (DC) and Vslv (AC)) is applied to the developing roller 31, the toner flies from the developing roller 31 to the photosensitive drum 1a due to a potential difference between the developing roller 31 and the photosensitive drum 1a. The electrostatic latent image on the photosensitive drum 1a is developed.

  The toner remaining on the developing roller 31 without being used for development is transported again to the region R between the developing roller 31 and the magnetic roller 30 by the rotation of the developing roller 31, and is collected by the magnetic brush on the magnetic roller 30. Then, the magnetic brush is peeled off from the magnetic roller 30 at the same polar portion of the fixed magnet body of the magnetic roller 30, and then falls into the supply transfer chamber 22. In the collection operation using the magnetic brush, since the toner on the developing roller 31 is not completely collected, a later-described toner collection operation is performed at a predetermined timing.

  In addition, in the vicinity of the developing roller 31 (here, a portion on the upstream side in the rotation direction of the developing roller 31 with respect to the facing region R), a suction port (through hole) for sucking air and floating toner around the facing region R. ) 40 are provided. A first duct 42 is connected to the suction port 40. As shown in FIG. 3, a second duct 44 is connected to a first duct 42 of each of the developing devices 3 a to 3 d via a connecting portion 43. The first duct 42, the connecting portion 43, and the second duct 44 constitute the toner suction path 41. The first duct 42 is an example of the “duct” of the present invention.

  The suction port 40 (see FIG. 2) and the first duct 42 are formed so as to extend along the longitudinal direction of the developing devices 3a to 3d, and are formed by the developing container 20. The detailed structure of the first duct 42 will be described later. The connecting portion 43 gathers the plurality of first ducts 42 and connects to the second ducts 44.

  The second duct 44 is arranged to extend in a direction perpendicular to the first duct 42. The second duct 44 is provided with a toner collecting container 45. On the downstream side of the toner collecting container 45, a fan 46 for generating an air flow in the toner suction path 41 is provided. The air in the developing container 20 (see FIG. 2) is sucked into the first duct 42 from the suction port 40 by the fan 46, and is externally provided to the outside of the image forming apparatus 100 via the connecting portion 43, the second duct 44, and the toner collecting container 45. Is discharged.

  The toner collecting container 45 is provided with filters 47a and 47b. The toner sucked together with the air by the fan 46 is collected by the filters 47a and 47b. This toner collection container 45 is replaced with a new one at the time of maintenance. Note that, depending on the size of the toner collecting container 45, the toner collecting container 45 may not be replaced at the time of maintenance, and one toner collecting container 45 may be used until the life of the image forming apparatus 100. It is also possible to replace only the filters 47a and 47b without replacing the entire toner collecting container 45.

  During the developing operation and the non-developing operation, the fan 46 is rotated at a predetermined rotational speed. As a result, an air flow F as shown in FIG. 2 is generated in the developing device 3a. That is, an airflow F flowing from the opening 20b to the suction port 40 is generated. For this reason, the floating toner in the developing device 3a is suppressed from scattering outside through the opening 20b.

  At the time of the developing operation, as described above, the toner remaining on the developing roller 31 without being used for the development is collected by the magnetic brush on the magnetic roller 30.

  On the other hand, during a non-development operation, the toner on the developing roller 31 is collected by the magnetic roller 30 at a predetermined timing by an electric force in addition to the scraping force of the magnetic brush. Specifically, in this toner collecting operation, a bias smaller than that during the developing operation or a bias in a direction opposite to that during the developing operation is applied between the developing roller 31 and the magnetic roller 30, and the toner on the developing roller 31 is removed. It jumps to the magnetic roller 30 and is collected. Note that the amount of floating toner in the developing devices 3a to 3d during the toner collecting operation increases compared to the amount of floating toner during the developing operation.

  The timing of performing the toner collecting operation may be performed each time the developing operation is completed (each sheet), or may be performed when the number of developed sheets reaches a predetermined number. Further, the toner collecting operation may be performed when the operation shifts from the developing operation to the standby operation. The operations of the fan 46, the developing devices 3a to 3d, and the like are controlled by a CPU (control unit) (not shown) that controls the entire image forming apparatus 100.

  Next, the structure of the first duct 42 will be described in detail.

  As shown in FIG. 2, the suction port 40 is formed in the upper surface 23 of the developing container 20 and communicates the inside and the outside of the developing container 20. On the upper surface portion 23, a side surface portion 24 is provided upright so as to surround the periphery of the suction port 40. A sheet-like cover member 50 is adhesively fixed to the upper end of the side surface portion 24. The first duct 42 is configured by the developing container 20 (the upper surface portion 23 and the side surface portion 24) and the cover member 50. The cover member 50 covers the upper surface of the developing container 20 and constitutes the upper surface of the first duct 42. The cover member 50 is a seal member for preventing toner from leaking from the inside of the first duct 42 to the outside.

  Here, the cover member 50 is configured to suppress the toner from adhering due to the action of static electricity. In the present embodiment, as shown in FIG. 4, the cover member 50 is formed of an insulating resin sheet such as a PET film, and the upper surface (first surface) 50a and the lower surface (second surface) 50b of the cover member 50. , A surfactant (antistatic agent) 55 is applied. Since the surfactant 55 absorbs moisture in the air, the accumulation of static electricity in the cover member 50 can be suppressed.

  As the surfactant 55, a surfactant having the same polarity as the charged polarity of the toner is used. Here, since the toner is a positively charged toner, a cationic surfactant is used as the surfactant 55.

  Further, as shown in FIG. 5, the cover member 50 may be formed of a conductive sheet made of a PET film or the like containing carbon. When a conductive sheet is used as the cover member 50, compared to when an insulating resin sheet is used, accumulation of static electricity on the cover member 50 can be suppressed, so that toner adheres to the cover member 50 due to the action of static electricity. Can be suppressed. When the cover member 50 is formed of a conductive sheet, it is not necessary to apply the surfactant 55 to the upper surface 50a and the lower surface 50b of the cover member 50.

  In the present embodiment, as described above, an antistatic agent (surfactant 55) is applied to the upper surface 50a of the cover member 50. Accordingly, it is possible to prevent the floating toner from adhering to the upper surface 50a of the cover member 50 due to static electricity. As a result, when the developing devices 3a to 3d are replaced, it is possible to suppress the worker's hands and clothes from being stained and the surroundings from being soiled due to toner scattering. Even when the cover member 50 is formed of a conductive sheet, it is possible to suppress the floating toner from adhering to the upper surface 50a of the cover member 50 due to static electricity. Therefore, when the developing devices 3a to 3d are replaced, It is possible to suppress the worker's hands and clothes from being stained and the surroundings from being stained due to toner scattering.

  Further, as described above, the outer surface of the developing container 20 and the cover member 50 constitute the first duct 42 communicating with the suction port 40, and the cover member 50 is configured to transfer the toner from the inside of the first duct 42 to the outside. This is a seal member for preventing leakage of water. Thus, the first duct 42 can be easily formed using the cover member 50, and the adhesion of the toner to the upper surface of the first duct 42 (the upper surface of the cover member 50) can be suppressed.

  Further, as described above, an antistatic agent (surfactant 55) is applied to the lower surface 50b of the cover member 50. Accordingly, it is possible to suppress the toner from adhering to the inner surface of the first duct 42 (the lower surface 50b of the cover member 50), so that it is possible to suppress the cross-sectional area of the first duct 42 from decreasing. . For this reason, since the toner suction force by the fan 46 can be suppressed from being reduced, the floating toner in the developing container 20 can be prevented from scattering (leaking) outside the developing container 20. Even when the cover member 50 is formed of a conductive sheet, the adhesion of the floating toner due to static electricity to the lower surface 50b of the cover member 50 can be suppressed. Can be suppressed from becoming smaller.

  Also, as described above, even when the cover member 50 is formed of an insulating resin sheet that is easily charged, the surfactant 55 as an antistatic agent is applied to the upper surface 50a of the cover member 50. By doing so, it is possible to easily prevent the surfactant 55 from absorbing moisture in the air and accumulating static electricity in the cover member 50.

  Further, as described above, the surfactant 55 is a cationic surfactant having the same polarity as the charged polarity of the toner. Thereby, the adhesion of the toner to the cover member 50 can be more effectively suppressed.

  Next, a confirmation experiment performed to confirm the effect of the present embodiment will be described. This confirmation experiment was performed on Examples 1 and 2 corresponding to the above embodiment and a comparative example not corresponding to the above embodiment.

[Example 1]
An image in which the cover member 50 is formed of an insulating PET film and the developing devices 3a to 3d in which the cationic surfactant 55 is applied to the upper surface 50a and the lower surface 50b of the cover member 50 by several μm (about 1 to 2 μm) respectively are mounted. The forming apparatus 100 was a first embodiment.

[Example 2]
The cover member 50 was formed of a conductive sheet made of a PET film containing carbon, and the developing devices 3a to 3d in which the surface resistance value of the cover member 50 was 1 × 10 ⁶ Ω to 1 × 10 ⁷ Ω were mounted. The image forming apparatus 100 is a second embodiment. The surfactant 55 was not applied to the upper surface 50a and the lower surface 50b of the cover member 50.

[Comparative example]
An image forming apparatus 100 in which the cover member 50 is formed of an insulating PET film and the developing devices 3a to 3d in which the upper surface 50a and the lower surface 50b of the cover member 50 are not coated with the surfactant 55 is used as a comparative example. .

  Then, for Examples 1 and 2 and Comparative Example, the amount of toner adhering to the upper surface 50a and the lower surface 50b of the cover member 50 after the printing operation of 20,000 sheets was measured. Table 1 shows the results.

Referring to Table 1, the amount of toner adhered to the cover member 50 of Examples 1 and 2 was about 0.5 g / m ² , and the amount of toner adhered to the cover member 50 of the comparative example was about 3 g / m ² . there were. As described above, in Examples 1 and 2, it was found that the adhesion of the toner to the upper surface 50a and the lower surface 50b of the cover member 50 can be suppressed as compared with the comparative example.

  This is considered to be due to the following reasons. That is, by applying the surfactant 55 to the upper surface 50a and the lower surface 50b of the cover member 50, or by forming the cover member 50 with a conductive sheet, it is possible to suppress accumulation of static electricity in the cover member 50. Thus, the electrostatic force acting on the floating toner could be reduced. As a result, it is considered that the adhesion of the toner to the upper surface 50a and the lower surface 50b of the cover member 50 could be suppressed.

  It should be understood that the embodiments disclosed this time are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description of the embodiments and examples, and includes all modifications within the scope and meaning equivalent to the terms of the claims and examples.

  For example, an example in which the present invention is applied to a color printer has been described, but the present invention is not limited to this. Needless to say, the present invention can be applied to various image forming apparatuses including a developing device having a developing roller, such as a monochrome printer, a monochrome copying machine, a digital multifunction peripheral, and a facsimile.

  Further, in the above embodiment, the example in which the antistatic agent (the surfactant 55) is applied to both the upper surface 50a and the lower surface 50b of the cover member 50 has been described, but the present invention is not limited to this, and the upper surface of the cover member 50 is not limited thereto. An antistatic agent (surfactant 55) may be applied only to 50a.

  Further, in the above-described embodiment, an example is described in which a surfactant (here, a cationic surfactant) having the same polarity as the charged polarity of the toner is used. However, the present invention is not limited to this, and the polarity is opposite to the charged polarity of the toner. May be used. Further, an antistatic agent other than the surfactant may be used as the antistatic agent.

  Further, in the above embodiment, the example in which the first duct 42 is provided in the developing container 20 and the cover member 50 is provided so as to configure the upper surface of the first duct 42 has been described, but the present invention is not limited thereto. For example, a cover member 50 that covers at least a part of the developing container 20 may be provided without providing the first duct 42 in the developing container 20.

  Further, in the above-described embodiment, the example in which the cover member 50 is provided on the upper surface portion 23 of the developing container 20 has been described. You may.

  Further, in the above-described embodiment, the example in which the developing roller 31 and the magnetic roller (toner supply roller) 30 are provided in the developing container 20 has been described. However, the present invention is not limited thereto, and the developing container 20 may be provided with a magnetic roller (toner supply roller). ) 30 may not be provided.

1a to 1d Photoconductive drum (image carrier)
3a to 3d Developing device 20 Developing container (casing)
30 Magnetic roller (toner supply roller)
31 developing roller 35 regulating blade 40 suction port (through hole)
42 1st duct (duct)
50 cover member 50a upper surface (first surface)
50b lower surface (second surface)
55 surfactant (antistatic agent)
100 Image forming apparatus

Claims (6)

A developing roller that is arranged to face the image carrier on which an electrostatic latent image is formed, and supplies toner to the image carrier in a region facing the image carrier;
A casing accommodating the developing roller;
With
The casing is provided with a sheet-like cover member that covers at least a part of the casing,
A developing device, wherein an antistatic agent is applied to a first surface of the cover member opposite to the casing, or the cover member is formed of a conductive sheet. A toner supply roller disposed to face the developing roller and supplying toner to the developing roller in a region facing the developing roller;
A regulating blade that is disposed opposite to the toner supply roller at a predetermined interval,
Further comprising
In the casing, a through-hole communicating the inside and the outside of the casing is formed,
A duct communicating with the through hole is configured by the outer surface of the casing and the cover member,
The developing device according to claim 1, wherein the cover member is a seal member that prevents the toner from leaking from the inside of the duct to the outside.   The developing device according to claim 2, wherein the antistatic agent is applied to a second surface of the cover member facing the casing. The cover member is formed of an insulating resin sheet,
The developing device according to claim 1, wherein at least the first surface of the cover member is coated with a surfactant serving as the antistatic agent.   The developing device according to claim 4, wherein the surfactant is a surfactant having the same polarity as the charged polarity of the toner.   An image forming apparatus comprising the developing device according to claim 1.

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