JP2003084558A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of restraining fogging by reducing the variation of electrification. SOLUTION: A developing roller 9, a toner carrying roller 10, a developing blade 11, a toner electrifying roller 12, a 2nd toner carrying roller 13 and a 2nd developing blade 14 are provided inside the developing device 5. The roller 12 comes into contact with the roller 10 and rotates in the same direction as the roller 10, and has the same constitution as the roller 9. The roller 13 is provided to come into contact with the roller 12 and rotate in the same direction as the roller 12, and is constituted of material equivalent to that of the roller 10. Negative voltage is applied to the rollers 12 and 13. The blade 14 is constituted of the same material as the blade 11, and its pressing force is set to be weaker than that of the blade 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for developing an electrostatic latent image on an electrostatic latent image carrier used in an electrophotographic copying machine, a printer to which an electrophotographic method is applied, or the like.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic copying machine, a printer to which an electrophotographic method is applied, or the like has a built-in developing device for carrying toner as a developer to an electrostatic latent image carrier for development. The developing device is internally in contact with a toner transport roller for transporting toner, and is in contact with the toner transport roller on the one hand, and is in contact with the electrostatic latent image carrier, that is, a photosensitive drum on the other hand And a developing roller that sends the generated toner to the photosensitive drum. By supplying toner from the developing roller to the photosensitive drum on which the electrostatic latent image is formed, the electrostatic latent image is developed and a visible image by the toner is obtained.

On the surface of the developing roller, a developing blade that frictionally charges the toner and regulates the layer thickness of the toner is in pressure contact. The toner is negatively charged by the frictional charging by the developing blade. The surface of the photosensitive drum is first uniformly negatively charged, and then an electrostatic latent image area is formed by LED light or laser light according to image information. The negatively charged toner is attracted to the area of the electrostatic latent image, so that the development is performed.

[0004]

In the above-described conventional developing device, since the toner is charged only by the toner conveying roller and the developing blade that are in pressure contact with the developing roller, the variation in charging is relatively large, that is, the charging distribution is small. There is a problem that the toner becomes wider and adheres to an area other than the area of the electrostatic latent image when the toner is attracted to the photosensitive drum, causing so-called fogging.

[0005]

In order to solve the above problems, the present invention provides a developing roller for supplying a developer to an electrostatic latent image bearing member for development, and a developing roller for supplying a developer to the developing roller. A developing device having a developer carrying roller is characterized in that a developer charging means for charging the developer is provided before the developer carrying roller. As a developer charging means,
A first charging roller that rotates in contact with the developer transport roller and a second charging roller that rotates in contact with the first charging roller may be provided. Further, as the developer charging means, a charge bar which is in frictional contact with the developer conveying roller at its lower portion may be provided.

With the above arrangement, the frictional charge of the developer is increased by the first charging roller and the second charging roller, or the charging bar, and the variation in charging is reduced. As a result, it can be expected that fogging will be reduced.

Further, as the developer charging means, a plurality of net-like members each composed of a conductive or semi-conductive member and treated with a coupling agent having a functional group may be provided. In that case, the plurality of mesh members may be configured in layers or may be configured to be concentrically rotatable. Then, a voltage may be applied to the plurality of mesh members to vibrate the plurality of mesh members.

According to the above construction, the developer is frictionally charged by contacting the plurality of net-like members, and as a result, it is expected that the variation in charging is reduced and the fogging is reduced.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Note that elements common to the drawings are given the same reference numerals. FIG. 1 is a schematic configuration diagram showing an image forming apparatus equipped with the developing device of the first embodiment, and FIG.
FIG. 3 is a schematic configuration diagram showing the developing device of the embodiment. First, an image forming apparatus equipped with the developing device of the present invention will be described.

In FIG. 1, an image forming apparatus 1 has a photosensitive drum 2 as an electrostatic latent image carrier, around which a charging device 3, an exposure device 4, a developing device 5, a transfer roller 6 and a cleaning device. 7 are arranged respectively. The photoconductor drum 2 is made of an organic photoconductor (OPC) type photoconductive material and has a recording surface smaller than the area of an image to be recorded.
Rotate in the direction of arrow A.

As the charging device 3, there are currently three types of devices. First, 10 ³ to 10 ⁹ Ωcm
It has an electric resistance of 2 to 10 mm and a thickness of 2 to
400 to 5 conductive fibers made by dispersing conductive carbon in 15 denier rayon or nylon fibers.
A charging device using a plate-shaped brush bundled with a conductive support plate such as aluminum or stainless at a density of 00 / cm, and the charging system is called a brush charging system.

In the second charging device, a high voltage of about 5 KV is applied to a thin metal wire having a diameter of about 50 μm to cause corona discharge, and the generated ions are applied to the surface of the photosensitive drum 2 to charge it. This is called corona discharge method. This method is the most general, and uniform charging can be obtained at low cost, but it has a drawback that it requires a large space as the speed increases.

The third charging method is called a roller charging method, in which conductive carbon is dispersed in epichlorohydrin rubber or urethane rubber and a roller having an electric resistance of 10 ³ to 10 ⁹ Ωcm is attached to the photosensitive drum 2. Contact
By applying a voltage of several KV to this, discharge is generated in the vicinity of the contact point to perform charging.
This method has been widely used in recent years mainly for low-end equipment because it generates less ozone and saves space, but problems such as roller cost and charging unevenness (unevenness) due to roller contamination are problems. Has been done.

The exposure device 4 irradiates the surface of the charged photosensitive drum 2 with issuing diode (LED) light or laser light according to the image information to be recorded, and forms an electrostatic latent image in the charged area. .

The transfer roller 6 is substantially the photosensitive drum 2.
Is provided below the surface of the photosensitive drum 2 so as to face the peripheral surface thereof, and the surface layer has an electric resistance of 10 ⁵ to 10 ¹⁰ Ωcm. The transfer roller 6 adds a plus 800 to the back surface of the sheet conveyed between the photosensitive drum 2 and the transfer roller 6.
A voltage of ˜2200 V is applied to electrostatically attract the toner on the surface of the photoconductor drum 2 and transfer the toner onto the paper. Since such a contact type transfer means exhibits stable transfer characteristics even under high humidity, the photosensitive drum 2 after transfer is performed.
Since the amount of toner remaining on the top can be reduced, it has the effect of reducing the burden of cleaning, and also has the effect of removing paper dust during transfer, preventing the mixture of paper dust into the toner. can do.

The cleaning device 7 is composed of a semi-conductive roller, and when a positive voltage is applied, the toner remaining on the photosensitive drum 2 after transfer is sucked to clean the photosensitive drum 2. I do.

1 and 2, the developing device 5 contains a so-called one-component developer (toner) 8 having a triboelectric chargeability (volume average particle diameter, 6 to 15 μm). Developing device 5
Inside, a developing roller 9, a toner carrying roller 10, a developing blade 11, a toner charging roller 12, a second toner carrying roller 13 and a second developing blade 14 are provided, respectively.

The developing roller 9 conveys the toner 8 to a position facing the photoconductor drum 2 to develop the electrostatic latent image on the surface of the photoconductor drum 2, and at the same time, the toner remaining on the photoconductor drum 2 is conveyed. Are collected and returned into the developing device 5. The developing roller 9 has a conductive surface layer having an electric resistance of 10 ² to 10 ⁸ Ωcm, and the conductive surface layer is made of urethane, silicone rubber, diene rubber (EPDM: ethylene propylene trimer, etc.) or the like. It is configured by dispersing conductive fillers (conductive carbon, metal powder, etc.).

The developing blade 11 frictionally charges the toner 8 by pressing it against the developing roller 9 and forms a thin layer of the toner 8 on the surface of the developing roller 9, and is made of phosphor bronze, urethane, silicone resin, or these. Composed of composite materials. The toner 8 passing between the developing blade 11 and the developing roller 9 is triboelectrically charged with the same polarity (minus) as the charged surface of the photosensitive drum 2, and
Layers-3 layers (6-45 micron thick) of toner layers are formed.

Considering the triboelectrification of the toner 8, it is necessary to select the material of the surface layer of the developing roller 9 that has appropriate elasticity and friction. For example, as the material of the surface layer of the developing roller 9, 10 to 3 conductive carbon is added to urethane resin.
The one formed by applying a mixture of 0 weight percent is used.

The toner conveying roller 10 plays a role of preventing aggregation of the toner 8, feeding and supplying, and scraping the developing roller 9 so that the toner 8 does not excessively adhere to the developing roller 9. The toner conveying roller 10 is a conductive roller having an electric resistance of 10 ² to 10 ⁶ Ωcm, and urethane or silicon rubber, diene rubber (EPDM, etc.), etc., is filled with a conductive filler (conductive carbon, metal powder, etc.). It is composed of dispersed elements.

Bias voltages are applied to the developing roller 9 and the toner conveying roller 10, and are about −150 to −350 V and −400 to −600 V, respectively.

The toner charging roller 12 is in contact with the toner conveying roller 10, rotates counterclockwise, and has the same structure as the developing roller 9. That is, the toner charging roller 12 has a conductive surface layer having an electric resistance of 10 ² to 10 ⁸ Ωcm, and the conductive surface layer is conductive to urethane, silicone rubber, diene rubber (EPDM, etc.) or the like. It is configured by dispersing fillers (conductive carbon, metal powder, etc.). Toner charging roller 1
A voltage of −500 V to −700 V is applied to the line 2.

The second toner carrying roller 13 is provided so as to come into contact with the toner charging roller 12 and rotate in the same direction as the toner charging roller 12, and is made of the same material as the toner carrying roller 10. That is, 10 ² to 10 ⁶ Ωcm
Is a conductive roller having electric resistance, and is made of urethane, silicon rubber, diene rubber (EPDM, etc.), etc., in which conductive fillers (conductive carbon, metal powder, etc.) are dispersed. A voltage of −550V to −1000V is applied to the second toner transport roller 13.

The second developing blade 14 is the developing blade 1.
Like No. 1, it is composed of phosphor bronze, urethane, silicon resin, or a composite material thereof. The second developing blade 14 is arranged so as to press the toner charging roller 12 by pressing means (not shown), but the pressing force is set to be weaker than that of the developing blade 11. That is, the second developing blade 14 is attached to the toner charging roller 12 by 5 to 5.
The pressure contact force is set so as to form 10 toner layers (thickness of 30 to 150 μm).

Next, the operation of the developing device of the first embodiment will be described. In FIG. 2, the developing roller 9, the toner carrying roller 10, the toner charging roller 12, and the second toner carrying roller 13 all rotate in the same phase in the arrow B direction.
The relative speed at the contact portion of each roller is the sum of the rotation speeds of the rollers in contact with each other. First, the second toner carrying roller 13
While negatively frictionally charging the toner 8 at the contact portion with the toner charging roller 12, the toner charging roller 12
To the side. Then, the second developing blade 14 negatively frictionally charges the toner 8 on the toner charging roller 12 and forms a layer of the toner 8 on the toner charging roller 12. The toner charging roller 12 sends the toner 8 formed in layers on its surface to the toner carrying roller 10 side while further negatively frictionally charging the toner 8 at the contact portion with the toner carrying roller 10.

The toner carrying roller 10 carries the sent toner 8 to the developing roller 9 side while negatively frictionally charging the toner 8 at the contact portion with the developing roller 9. Then, the developing blade 11 negatively frictionally charges the toner 8 on the developing roller 9 and forms a layer of the toner 8 on the developing roller 9. The layer thickness in this case is 1 to 3 layers (6
˜45 μm thickness).

In FIG. 1, the toner 8 adhering to the surface of the developing roller 9 is attracted to the area of the electrostatic latent image on the surface of the photoconductor drum 2 at the contact portion with the photoconductor drum 2 for developing. Be served. The toner 8 attached to the surface of the photoconductor drum 2 moves to the transfer portion by the rotation of the photoconductor drum 2 and is transferred to a sheet (not shown) by the transfer roller 6. Toner remaining on the photosensitive drum 2 without being transferred
Are removed by the cleaning device 7.

In the above-described embodiment, the toner charging roller 12, the second toner carrying roller 13 and the second developing roller 14 are provided. However, these three members are set as one set and another set is provided in the developing device 5. It may be provided in the.
Then, the triboelectrification of the toner 8 is sufficiently performed.

As described above, according to the first embodiment,
Since the toner charging roller 12, the second toner conveying roller 13 and the second developing roller 14 are provided, the frictional charging of the toner can be sufficiently performed until the toner reaches almost saturation, and the variation in charging is reduced. As a result, it is possible to reduce the occurrence of fogging during development.

Next, a second embodiment of the present invention will be described. FIG. 3 is a schematic configuration diagram showing the developing device according to the second embodiment. The developing device of the second embodiment is provided with a charging bar instead of the roller member.

In FIG. 3, the developing device 20 according to the second embodiment is provided with charging bars 21 and 22 in addition to the developing roller 9, the toner conveying roller 10 and the developing blade 11. The charging bars 21 and 22 have the same configuration and both are in contact with the toner carrying roller 10. Charging bar 2
Nos. 1 and 22 have a conductive surface layer having an electric resistance of 10 ² to 10 ⁸ Ωcm, and the conductive surface layer is made of urethane or silicon rubber, diene rubber (EPDM, etc.), etc. with a conductive filler (conductive material). Carbon, metal powder, etc.) are dispersed. Charging bar 21, 2
A voltage of −500 V to −700 V may be applied to each of the two.

Next, the operation of the second embodiment will be described.
Since the charging bars 21 and 22 are in contact with the toner conveying roller 10, the toner 8 is negatively frictionally charged at the contact portion by the rotation of the toner conveying roller 10. The toner 8 that has been triboelectrically charged is conveyed to the developing roller 9 side by the toner conveying roller 10, and further negatively frictionally charged at the contact portion between the toner conveying roller 10 and the developing roller 9. The toner 8 supplied to the developing roller 9 is triboelectrically negatively charged by the developing blade 11, and a layer thereof is formed on the developing roller 9.

As described above, according to the second embodiment,
Since the process of frictionally charging the toner 8 is increased, the variation in charging is reduced, and the occurrence of fogging during development can be reduced. In general, the charge of the toner 8 decreases with time and is greatly affected by the usage environment. Although a strong charging ability is required to cope with such a change, each embodiment of the present invention can sufficiently meet such a requirement.

Next, a third embodiment of the present invention will be described. FIG. 4 is a schematic configuration diagram showing the developing device of the third embodiment, and FIG. 5 is a perspective view showing the charging mechanism in the third embodiment.

4 and 5, the developing device 30 of the third embodiment includes a developing roller 9 and a toner conveying roller 1.
0, the developing blade 11, and the charging mechanism 31 is provided on the opposite side of the developing roller 9 with respect to the toner conveying roller 10. The charging mechanism 31 is composed of a plurality of meshes 32 which are arranged in a step-like manner and are spaced apart from each other, and actuators 33 and 34 which are provided at both ends of each mesh 32.

The mesh 32 is composed of a conductive or semi-conductive fiber such as a metal wire or a carbon fiber having a high tension, and the surface of the fiber is treated with a coupling agent having a basic functional group such as aminosilane. ing. The meshes 32 all have the same configuration. The fineness of the mesh 32 is about 50 to 1000 μm, and the interval between the meshes 32 is about 1 to 10 mm.
About 0 meshes 32 are stacked.

To each mesh 32, a bias voltage of up to about -5 KV is applied. The actuators 33 and 34 are composed of piezoelectric elements or the like and have a function of giving vibration to the mesh 32.

Next, the operation of the third embodiment will be described.
When an AC voltage of about 100 Hz to 10 KHz is applied to the actuators 33, 34, the actuators 33, 3
4 vibrates, and this vibration is transmitted to the mesh 32. Due to the vibration of the mesh 32, the toner 8 existing between the mesh 32 vibrates. The vibration amplitude of the toner 8 is about 50 μm at the maximum when the vibration frequency is low.

The toner 8 passes through the fine meshes of the mesh 32 to suppress aggregation. Further, the vibration facilitates contact with the mesh 32, but repeated contact with the mesh 32 causes triboelectrification due to the basic functional group of the fiber. Generally, the electrostatic charge due to friction of powder increases as the impulse of contact increases. Although a large amount of fluid is required to charge the entire toner in the developing device, the volume of the developing device is limited, and sufficient friction cannot be obtained only by friction between the developing roller 9 and the toner conveying roller 10. However, by disposing a plurality of meshes 32 and vibrating the meshes 32, the fluidity of the toner 8 and the uniformity of charging can be improved.

Next, a fourth embodiment will be described. FIG. 6 is an exploded perspective view showing the charging mechanism of the fourth embodiment.
The fourth embodiment is a modification of the charging mechanism shown in the third embodiment.

In FIG. 6, a charging mechanism 41 according to the fourth embodiment has a plurality of meshes 32 arranged in a step-like manner with a space between each other, and actuators 33 provided at both ends of each mesh 32. 34, and meshes 42 and 43 provided on both sides of each mesh 32. Further, charge carriers 44 are introduced into the mesh 32 group.

Like the mesh 32, the meshes 42 and 43 on both sides are made of conductive or semi-conductive fibers such as metal wires and carbon fibers having high tensile strength, and the surface of the fibers is a base such as aminosilane. It is treated with a coupling agent having a functional group. Mesh 4
The fineness of the meshes of Nos. 2 and 43 is the same, and is about 50 to 1000 μm. In addition, the mesh 42, 43 minus 5KV
A bias voltage is applied to which a direct current or an alternating current, or a direct current plus an alternating current is applied.

The particle size of the carrier 44 is the mesh 32,
The size larger than the size of the eyes of 42 and 43 is used. As the carrier 44, it is advantageous in terms of cost to use a carrier for electrostatic latent image development in which inorganic oxide fine particles are dispersed in a magnetic core particle resin which is generally used in a non-magnetic two-component developing method. However, in the present embodiment, it is not necessary to collect the carrier 44 with a magnet, and it is possible to use a carrier for electrostatic latent image development in which inorganic oxide fine particles are dispersed in a resin having no magnetic core particles. Is.

Next, the operation of the fourth embodiment will be described.
When an AC voltage of about 100 Hz to 10 KHz is applied to the actuators 33, 34, the actuators 33, 34
Vibrates, and this vibration is transmitted to the mesh 32. Due to the vibration of the mesh 32, the toner 8 existing between the mesh 32
And the carrier 44 vibrates. The vibration amplitude of the toner 8 and the carrier 44 is about 50 μm at the maximum when the vibration frequency is low.

The toner 8 passes through the fine meshes of the meshes 32, 42 and 43 to suppress aggregation. Further, by vibrating, the mesh 32, 42, 43 and the carrier 44 are repeatedly contacted and frictionally charged. As described above, in the fourth embodiment, as compared with the third embodiment, the charging due to the contact of the toner 8 with the carrier 44 is increased, and the charging uniformity is further improved.

Next, a fifth embodiment will be described. FIG. 7 is a perspective view showing the charging mechanism of the fifth embodiment. Fifth
In this embodiment, the charging mechanism has a rotatable structure.

Referring to FIG. 7, the charging mechanism 51 of the fifth embodiment has a cylindrical mesh 52 arranged concentrically.
And side plates 53, 54 provided at both ends of the mesh 52.
Composed of and. The mesh 52 is composed of a conductive or semi-conductive fiber such as a metal wire or a carbon fiber having a high tension, and the surface of the fiber is treated with a coupling agent having a basic functional group such as aminosilane. The meshes 52 all have the same configuration.

The fineness of the mesh 52 is 50 to 10
The mesh 52 has a distance of 1 to 10 μm.
About 10 meshes 52 are arranged concentrically in a size of about mm. To each mesh 52, a DC voltage or an AC voltage of up to about -5 KV, or a bias voltage obtained by adding an AC voltage to a DC voltage is applied.

The side plates 53 and 54 have meshes 5 from both ends.
2, which is made of stainless steel (such as SUS304) and has a shaft 5 at the center.
5, 56 are provided. A gear is attached to either one of the shafts 55 and 56 so that the rotational force is transmitted. The charging mechanism 51 is arranged in the developing device at substantially the same position as the charging mechanism 31 of the third embodiment shown in FIG.

Next, the operation of the fifth embodiment will be described.
When the rotational force is transmitted to a gear (not shown) attached to one of the shafts 55 and 56, the charging mechanism 51 rotates. The toner contacts the mesh 52 of the charging mechanism 51 and is frictionally charged. At the same time, the mesh 52 group is rotated and stirred.

Although the toner is vibrated by using the actuator in the third and fourth embodiments,
Since the charging mechanism 51 is rotated in the fifth embodiment, it can be rotated by utilizing the rotational force of a motor or the like, which is advantageous in terms of cost for vibrating the toner.

Next, a sixth embodiment will be described. FIG. 8 is a perspective view showing a charging mechanism of the sixth exemplary embodiment. Sixth
The embodiment is a modification of the charging mechanism of the fifth embodiment.

In FIG. 8, the charging mechanism 61 of the sixth embodiment has a carrier 62 introduced into the charging mechanism of the fifth embodiment in which a plurality of meshes are concentrically formed. The particle size of the carrier 62 is larger than the size of the mesh 63 of the charging mechanism 61. As the carrier 62, it is advantageous in terms of cost to use a carrier for developing an electrostatic latent image in which inorganic oxide fine particles are dispersed in a resin in the form of magnetic core particles, which is generally used in a non-magnetic two-component developing system. However, in the present embodiment, it is not necessary to collect the carrier 62 with a magnet, and it is possible to use a carrier for electrostatic latent image development in which inorganic oxide fine particles are dispersed in a resin having no magnetic core particles. Is.

Shaft 6 provided on side plates 64 and 65
When the rotational force is transmitted to a gear (not shown) attached to either one of 6, 6 or 67, the charging mechanism 61 rotates. The toner is the mesh 63 of the charging mechanism 61 and the carrier 6.
2 is contacted and frictionally charged. At the same time, the toner rotates together with the mesh 63 group and is agitated.

Further, in the sixth embodiment, since the charging mechanism 61 is rotated, it can be rotated by utilizing the rotating force of a motor or the like, which is advantageous in terms of cost for vibrating the toner. . That is, the sixth embodiment can achieve both the effects of the fourth embodiment and the effects of the fifth embodiment.

[0057]

As described in detail above, according to the present invention, since the developer charging means for charging the developer is provided in the preceding stage of the developer conveying roller, the triboelectric charge of the developer is increased,
The variation in charging becomes small. As a result, it can be expected that fogging will be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus including a developing device according to a first embodiment.

FIG. 2 is a schematic configuration diagram illustrating a developing device according to a first embodiment.

FIG. 3 is a schematic configuration diagram showing a developing device according to a second embodiment.

FIG. 4 is a schematic configuration diagram showing a developing device according to a third embodiment.

FIG. 5 is a perspective view showing a charging mechanism according to a third embodiment.

FIG. 6 is an exploded perspective view showing a charging mechanism according to a fourth embodiment.

FIG. 7 is a perspective view showing a charging mechanism of a fifth embodiment.

FIG. 8 is a perspective view showing a charging mechanism of a sixth exemplary embodiment.

[Explanation of symbols]

5 Development device 8 toner 9 Development roller 10 Toner transport roller 11 Development blade 12 Toner charging roller 13 Second toner transport roller 14 Second developing blade

Claims (12)

[Claims] 1. A developing device having a developing roller for supplying a developer to an electrostatic latent image carrier to perform development, and a developer conveying roller for supplying the developer to the developing roller, wherein the developer conveying roller is provided. And a developer charging means for charging the developer in the preceding stage. 2. The developer charging means includes a first charging roller that rotates in contact with the developer carrying roller, and the first charging roller.
2. The developing device according to claim 1, further comprising a second charging roller that rotates in contact with the charging roller. 3. The developing device according to claim 2, wherein a voltage is applied to the first and second charging rollers. 4. The developing device according to claim 1, wherein the developer charging unit is a charging bar that is in frictional contact with the developer transport roller at a lower portion thereof. 5. The developing device according to claim 4, wherein a plurality of the charging bars are provided, and a voltage is applied to the charging bars. 6. The developing device according to claim 1, wherein the developer charging unit is composed of a conductive or semi-conductive member, and is composed of a plurality of mesh members treated with a coupling agent having a functional group. . 7. The developing device according to claim 6, wherein the plurality of mesh members are formed in layers. 8. The developing device according to claim 6, wherein the mesh member is configured to be rotatable in a cylindrical shape. 9. The developing device according to claim 6, wherein a voltage is applied to the mesh member. 10. The developing device according to claim 6, further comprising an actuator that vibrates the mesh member. 11. The developing device according to claim 10, wherein the developer charging unit has a function of stirring the developer. 12. The developing device according to claim 7, wherein a carrier is introduced between the plurality of mesh members.