JP2013210436A - Developing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device.SOLUTION: A developing device 4 having such a configuration that a developer is made into a cloud by the application of a bias voltage from alternately different drive power sources includes a seal member 45 preventing the developer from being scattered from a developer storage part. The seal member 45 is provided in such a state that a predetermined gap G is set with respect to the surface of a flare roller 40 and the seal member 45 is separated from the surface of the flare roller 40. It is constituted so that in the seal material, a ventilation part 45A is provided in a part of a wall surface facing the flare roller 40 and a supply roller 41 supplying the developer to the flare roller 40, to avoid pressure resistance to the developer entering from a facing gap entrance side and pressure rise in the developer storage part.

Description

  The present invention relates to a developing device and an image forming apparatus, and more particularly to a mechanism for preventing toner scattering from the developing device.

As is well known, in an image forming apparatus such as a copying machine, a printer, or a printing machine, an electrostatic latent image formed on a photosensitive member, which is a latent image carrier, is visualized by a developer supplied from a developing device. It is processed.
The visible image-processed toner image is transferred to a transfer material, and is then fixed by heating and pressurizing with a fixing device so that the toner melts and permeates to form a copy image.

  Some image forming apparatuses are configured to form not only a single color but also a plurality of colors such as full colors. In this case, images of different colors formed in a plurality of image forming units are belted. In some cases, a superimposed image is transferred onto a recording medium such as a recording sheet (secondary transfer) after being sequentially transferred (primary transfer) to an intermediate transfer body such as the above.

On the other hand, in a developing device used for image formation, a configuration using a one-component developer not containing a carrier in addition to a two-component developer containing a carrier and a toner is known. There is a configuration using a non-magnetic toner as the agent.
As one development method using non-magnetic toner, the toner layer is transported while hopping the toner by an alternating electric field applied to the surface of the developer carrier without directly contacting the electrostatic latent image carrier such as a photoreceptor. In addition, there is a non-contact developing method in which toner in this state is attached to an electrostatic latent image by electrostatic attraction using an electrostatic latent image on the latent image carrier side (for example, Patent Document 1).

  On the other hand, as a configuration for transporting toner while hopping, a plurality of electrodes connected to different electric paths at predetermined intervals are arranged on the surface of the toner carrier so that the electric field between the electrodes changes with time. There has been proposed a configuration in which bias means for applying a bias is provided, and toner is ejected in a cloud shape by an alternating electric field formed by a bias applied between the electrodes and conveyed toward a developing area that is a position facing the photoconductor. (For example, Patent Documents 2 and 3).

  In the method in which the toner in the hopping state as described above is attracted to the electrostatic latent image by the electrostatic attraction of the electrostatic latent image, the electrostatic charge from the carrier, the toner, and the electrostatic latent image, such as a two-component developer, is used. Since the relationship is based on the direct action of the electrostatic attraction of the electrostatic latent image on the toner, not the relationship with the attraction, it is possible to attach the toner to the electrostatic latent image at a low potential. The reproducibility at the boundary with the part can be exhibited well.

In the non-contact development method using toner hopping, the binding force of the toner on the developer carrying member is very weak unlike the case of using a magnetic brush.
For this reason, when the toner that has not been developed is collected in the developer container of the developing device, as disclosed in, for example, JP-A-2002-207355 (reference document), a developer carrier If it collides with a blocking member such as a seal member that contacts the surface and prevents the toner from flowing out from the inside of the developing device, it may leak toward the developing region when it rebounds at that position.

The seal member is a member for preventing leakage of the developer from the developer accommodating portion. When the pressure in the developer accommodating portion reaches the atmospheric pressure or higher, the seal member is moved from the contact position with the developer carrying member to the outside. Not only the collected developer blows out from the developer container, but also the weakly binding toner that is in the state of being collected by the blown air is blown off from the periphery of the developing device. May leak and scatter.
When toner scatters around the developing device, it may adhere to the recording medium passing through the developing area. If it adheres to the background of the recording medium, it will cause not only background staining but also the peripheral portion of the developing device. The equipment installed in the factory will be soiled.

  For this reason, it is important to reduce the amount of toner leakage as much as possible. For example, when the developing device alone is operated, if the image forming apparatus is a medium / low speed type office specification, the amount of developer leakage scattering is approximately every minute. It has been confirmed that the above-described problems do not occur if the amount is 1 mg or less per unit.

However, as described above, since the leakage of the toner is likely to occur under the condition where the binding force on the developer carrying member is weak, the inventor conducted an experiment, but depending on the conditions such as the pressure of the jet airflow, In some cases, a scattering amount of 600 mg or more was confirmed.
In order to solve such problems, it may be possible to change the mechanical characteristics such as pressure resistance of the seal member or to suppress internal pressure in the developer container, but when the pressure resistance of the seal member is increased, The pressure in the developer accommodating portion is considerably increased, and the pressure of the jet airflow is increased, so that toner leakage and scattering also occur strongly.

  An object of the present invention is to provide a developing device and an image forming apparatus having a configuration capable of reliably preventing the scattering and leakage of a developer used under a condition where the binding force to the developer carrying member is weak in view of the problems in the conventional developing device. Is to provide.

  In order to achieve this object, the present invention comprises a first electrode and a second electrode provided via an insulator with respect to the first electrode, the first electrode and the second electrode A developing device including a developer carrying member that forms a cloud by developing a bias voltage by applying a bias voltage that reverses a potential difference between them in time, and conveys the developer to a developing region in conjunction with the movement of the electrode, A development upper seal member that seals the inside and outside of the developer container by setting a gap at a predetermined interval with respect to the developer carrier at a position where the developer after passing through the development region enters the developer container. The seal member is provided with an inner and outer portions of the developer accommodating portion at an arbitrary position on a surface extending from a region facing the developer carrying member with the gap set to a region sealing the inside and outside of the developer accommodating portion. Ventilation part that can communicate with In the developing device, characterized in that.

  According to the present invention, the seal member that seals the inside and outside of the developer container is provided with a predetermined gap between the seal member and the developer carrier in the region facing the developer carrier. Since the clouded developer that has passed through and remains on the developer carrier can pass through the gap and enter the developer container, it is scattered to the periphery due to rebounding when it collides with the seal member Can be suppressed.

In addition, even when the pressure increase in the gap occurs and the movement of the developer is inhibited, the increased pressure can be released to the outside from the ventilation portion, so that the developer blows out due to the pressure increase in the gap. It is possible to prevent the abnormal situation from occurring.
As a result, it is possible to prevent the recording material from being contaminated by the developer leakage and the peripheral device from being damaged.

1 is a schematic diagram for explaining an example of an image forming apparatus using a developing device according to an embodiment of the present invention. It is a schematic diagram for demonstrating the structure of the image development apparatus concerning embodiment of this invention. FIG. 3 is a schematic diagram for explaining a configuration of a developer carrier used in the developing device illustrated in FIG. 2. FIG. 4 is a connection diagram for explaining an electrode structure in the developer carrying member shown in FIG. 3. FIG. 3 is a schematic view corresponding to FIG. 2 for explaining a main configuration of the developing device according to the embodiment of the present invention. It is a schematic diagram for demonstrating the principal part structure of the image development apparatus concerning another embodiment of this invention. It is a schematic diagram for demonstrating the modification of the principal part structure shown in FIG. It is a schematic diagram for demonstrating the modification of the principal part structure shown in FIG. It is a schematic diagram for demonstrating the modification of the principal part structure shown in FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
In FIG. 1, an image forming apparatus 100 includes a plurality of image forming units Y (yellow), M (magenta), C (cyan), and K (black) along the extending direction of an intermediate transfer belt 1 used in a primary transfer apparatus. A tandem type image forming apparatus.
The intermediate transfer belt 1 is wound around a plurality of rollers 1A and 1B so that one of the extended surfaces faces each of the image forming units described above.

The image forming units Y, M, C, and K have the same configuration. Now, the configuration of the Y (yellow) image forming unit will be described as follows.
The image forming unit Y is rotatably provided with a drum-shaped photoconductor (hereinafter referred to as a photoconductor) 2 that is used as a latent image carrier, and the peripheral portion will be described in detail with reference to FIG. 3. A writing unit (not shown), a developing device 4 and a cleaning device 5 are each composed of a process cartridge accommodated in a unit.
An intermediate transfer roller 6 used as a primary transfer device is disposed at a position facing the photoconductor 2 with the intermediate transfer belt 1 interposed therebetween.

  At a position facing one of the rollers 1B around which the intermediate transfer belt 1 is wound, an image superimposed and transferred to the intermediate transfer belt 1 onto a recording sheet as a recording material fed out from a paper feeding device (not shown). A secondary transfer device 7 for batch transfer is disposed.

In FIG. 2, the image forming unit Y performs visible image processing on the electrostatic latent image formed by light writing on the surface of the photoreceptor 2 with toner supplied from the developing device 4.
The image after the visible image processing is electrostatically transferred to the intermediate transfer belt 1, and the toner 2 after the transfer is removed of the residual toner in the cleaning device 5, but the cleaning device 5 in this embodiment is a photoconductor. 2 is configured to include a scraping blade 5A that comes into contact with 2 to remove residual toner, a lubricant 5B1 for reducing the frictional resistance of the photoreceptor 2, an application roller 5B2 for applying the lubricant 5B2 to the photoreceptor 2, and a leveling blade 5B3. Is used. In FIG. 2, for the sake of convenience, the developing device is displayed as the developing unit 4, and an area where the photosensitive member 2 and other devices than the developing device 4 are arranged is displayed as the photosensitive member unit.

On the other hand, the developing device 4 that performs visible image processing of an electrostatic latent image uses non-magnetic one-component toner, and without using a magnetic carrier such as a two-component developer, A configuration in which the image is attached to the electrostatic latent image by van der Waals force between the latent image and the latent image is used.
The developing device 4 includes a flare roller 40 that is a developer carrying member facing the photosensitive member 2, and frictionally charges the developer when rotating in the opposite direction to the flare roller 40 while being in contact with the flare roller 40 and the flare roller 40. A layer thickness regulating blade 44 that contacts the supply roller 41, the stirring paddle 42, the replenishing screw 43, and the flare roller 40 that can collect the developer remaining in the developer and regulates the layer thickness of the developer is housed in the developing unit. Is provided. In FIG. 2, reference sign SL indicates writing light for forming an electrostatic latent image.

The flare roller 40 employs a non-contact developing method in which the developer developer clouded by flying on the surface of the photoreceptor 2 on the surface of the photoreceptor 2 is caused to fly toward the photoreceptor 2. A predetermined gap is set with respect to 2 and separated.
The predetermined gap is set to a gap that does not hinder the progress of the clouded developer.

The configuration of the flare roller 40 is shown in FIGS.
In FIG. 3, on the surface of the flare roller 40, the first electrode 40A and the second electrode 40B are alternately arranged in parallel on the support substrate at a predetermined interval. The upper surface of each of the electrodes 40A and 40B is inorganic or organic. A surface protective layer made of an insulating material is provided.
As shown in FIG. 4, the first and second electrodes 40 </ b> A and 40 </ b> B are connected to different electric circuits, and each electric circuit has two different driving power sources on the main body side (in FIG. 3, A phase and B The drive voltage from (indicated as phase) is applied.
In the flare roller 40 having the above-described configuration, when the phase difference is 180 degrees from the driving power source of the two layers and a time-periodic potential difference occurs, unlike the case where a magnetic brush is used, the magnetic carrier is not restrained. The agent itself is made into a cloud by hopping the developer between the electrodes.

  The clouded developer is transported toward the development area facing the photoreceptor 2 by the movement of the electrode in conjunction with the movement of the flare roller surface, and the electrostatic latent image formed on the photoreceptor 2 in the development area. The electrostatic latent image is electrostatically attracted by van der Waals force generated between the image and the image. The first electrode group used for the flare roller in this embodiment is used as an odd-numbered electrode group, the second electrode group is used as an even-numbered electrode, and these odd-numbered electrodes and even-numbered electrodes are as described above. It is connected to different two-phase drive electrodes (A phase, B phase).

The flare roller 40 is configured by using an insulating material such as resin or a conductive material such as SUS as a support substrate, and an insulating film such as SiO ₂ is formed on the substrate.
As the first and second electrodes, a conductive material such as Al (aluminum), Cu, or Ni—Cr is formed on the support substrate to a thickness of 0.1 to 10 μm, preferably 0.5 to 2.0 μm. The film is formed and patterned into a desired electrode shape by a photolithographic process or the like.

  In FIG. 4, when the arrangement pitch (P) between the electrodes 40A and 40B is the electrode width (L) in the roller axis direction and the interval between adjacent electrodes, so-called electrode interval (R), P = L + R The electrode width (L) and the electrode spacing (R) affect the hopping characteristics of the developer, so the electrode width (L) is 1 to 20 times the average particle size of the toner powder that falls into the developer. The electrode spacing (R) is set to 1 to 20 times or less the average particle size of the powder.

The above-described electrode length (L) and adjacent interval (R) are set for the following reason.
That is, the toner between the electrodes moves to the adjacent electrode on the substrate surface by a substantially horizontal electric field. On the other hand, since the toner on the electrode is given an initial velocity having at least a component in the vertical direction, most of the toner flies away from the substrate surface.

  In particular, since the toner near the electrode end face moves over the adjacent electrode, when the electrode width L is wide, the number of toners on the electrode increases, and the toner having a large moving distance increases. Conveyance efficiency increases. However, if the electrode width L is too wide, the electric field strength in the vicinity of the center of the electrode is lowered, so that the toner adheres to the electrode and the transport efficiency is lowered. As a result of intensive studies, the present inventors have found that there is an appropriate electrode width for efficiently conveying and hopping powder at a low voltage.

  The electrode interval R determines the electric field strength between the electrodes from the relationship between the distance and the applied voltage. The narrower the interval R, the stronger the electric field strength, and the easier the initial speed of conveyance and hopping. However, for toner that moves from electrode to electrode, the distance traveled once is shortened, and the movement efficiency cannot be increased unless the drive frequency is increased. In this regard, as a result of intensive studies, the present inventors have found that there is an appropriate electrode interval for efficiently conveying and hopping powder at a low voltage.

  Further, the present inventors have also found that the thickness of the surface protective layer covering the electrode surface also affects the electric field strength on the electrode surface, in particular, the influence of the vertical component on the electric field lines is large, and determines the hopping efficiency.

  Therefore, by appropriately setting the relationship between the electrode width of the transport substrate, the electrode interval, and the surface protective layer thickness, the toner adsorption problem on the electrode surface can be solved, and efficient movement can be performed at a low voltage.

  More specifically, first, the electrode width L is a width dimension for carrying and hopping at least one toner when the electrode width L is set to one time the toner diameter (powder diameter). On the other hand, if it is narrower than this, the electric field acting on the toner is reduced, and the conveying force and the flying force are lowered, which is not sufficient for practical use.

  Further, as the electrode width L is increased, the electric field lines are inclined in the traveling direction (horizontal direction) particularly near the center of the upper surface of the electrode, a region having a weak vertical electric field is generated, and the hopping generation force is reduced. . When the electrode width L is too wide, in an extreme case, the image force according to the charged charge of the toner, the van der Waals force, the adsorbing force due to moisture, etc. may be superior, and toner deposition may occur.

  From the efficiency of conveyance and hopping, if the width is such that about 20 toners are placed on the electrode, adsorption is unlikely to occur, and the conveyance and hopping operations can be efficiently performed with a low voltage drive waveform of about 100V. If it is wider than that, a region where adsorption occurs partially occurs. For example, when the average particle diameter of the toner is 5 μm, it corresponds to a range from 5 μm to 100 μm.

  Regarding the electrode width L, a more preferable range is 2 times to 10 times the average particle diameter of the powder in order to drive the applied voltage by the drive waveform more efficiently at a low voltage of 100 V or less. By setting the electrode width L within this range, the decrease in electric field strength near the center of the electrode surface can be suppressed to 1/3 or less, and the decrease in hopping efficiency is 10% or less, resulting in a significant decrease in efficiency. Disappears. For example, this corresponds to a range of 10 μm to 50 μm when the average particle diameter of the toner is 5 μm.

  More preferably, the electrode width L is in the range of 2 to 6 times the average particle size of the powder. For example, this is a range corresponding to 10 μm to 30 μm when the average particle diameter of the toner is 5 μm. It has been found that efficiency within this range is very good.

The surface protective layer described _{above, SiO 2, BaTiO 2, TiO} 2, TiO 4, SiON, BN, TiN, can apply _Ta 2 _{O 5} or the like, the thickness is set to 0.5 to 30 m.
In addition, as a configuration of the surface protective layer, an organic material such as polycarbonate may be coated on SiO ₂ or the like. Note that zirconia or a material generally used as a coating material for a carrier of a two-component developer, such as a silicone resin, can also be selected. As described above, the surface protective layer is appropriately selected from the relationship between the insulating properties, durability, the production method of the flare roller itself, and the charge train with the developer to be used.

Next, the flare roller 40 manufacturing method will be described as follows.
In the present embodiment, considering that the flare roller 40 is used for a recording material having a long and large area of at least A4 vertical width of 21 cm and a horizontal width of 30 cm or more, the pattern of each electrode in such a large area is used. Formation is required.

Therefore, first, a case where a flexible electrode pattern is formed and wound around a support drum to form a flare roller will be described.
As an example of a substrate having a flexible fine pitch thin layer electrode, a polyimide base film (thickness 20 to 100 μm) is used as a base material (supporting substrate), and a 0.1 to 0.3 μm Cu film is formed thereon by vapor deposition. , Al, Ni—Cr and the like are formed. If it is 30-60 cm in width, it can be manufactured by a roll-to-roll apparatus, and mass productivity is greatly increased. The common bus line simultaneously forms electrodes having a width of about 1 to 5 mm.

  As a specific means of the vapor deposition method, a sputtering method, an ion plating method, a CVD method, an ion beam method, or the like can be used. For example, when an electrode is formed by sputtering, a Cr film may be interposed in order to improve adhesion with polyimide, and adhesion can also be improved by plasma treatment or primer treatment.

Further, as a method other than the vapor deposition method, a thin layer electrode can be formed also by an electrodeposition method.
In this case, an electrode is first formed on the polyimide substrate by electroless plating. It is possible to manufacture Ni films 1 to 3 um in a roll-to-roll manner by forming a base electrode by sequentially immersing in Sn chloride, Pd, and Ni chloride, followed by electrolytic plating in a Ni electrolyte.

  Then, electrodes are formed on these thin film electrodes by resist coating, patterning, and etching. In this case, if it is a thin layer electrode having a thickness of 0.1 to 3 μm, a fine pattern electrode having a width of 5 μm to several tens of μm or a space can be formed with high accuracy by photolithography and etching.

  Next, SiO2, BaTiO2, TiO2 or the like is formed as a surface protective layer to a thickness of 0.5 to 2 um by sputtering or the like. Alternatively, PI (polyimide) as a surface protective layer is applied to a thickness of 2 to 5 μm with a roll coater or other coating apparatus, and baked to finish. When troubles occur with PI, it is sufficient to form SiO2 on the outermost surface and other inorganic films to a thickness of 0.1 to 0.5 μm by sputtering or the like. Further, an organic material such as polycarbonate may be coated on SiO 2 or the like. It is also possible to select zirconia or a material generally used as a coating material for a carrier of a two-component developer, for example, a silicone resin.

 By configuring such a flexible substrate, it can be easily attached to a cylindrical drum, or partially curved.

 As another example, a polyimide base film (thickness 20 to 100 μm) is used as a base material (supporting substrate), and an electrode material is used thereon, such as Cu or SUS having a thickness 10 to 20 μm. Is possible. In this case, conversely, polyimide is applied on a metal material by a roll coater for 20 to 100 μm and baked. After that, the metal material is patterned into the shape of an electrode by photolithography and etching, and polyimide is coated on the electrode surface as a protective layer, and if there are irregularities according to the thickness of the metal material electrode, it is flattened and completed. To do.

  For example, when a polyimide material or polyurethane material having a viscosity of 50 to 10,000 cps, more preferably 100 to 300 cps is spin-coated and left standing, the unevenness of the substrate is smoothed by the surface tension of the material, and the outermost surface of the conveying member is Flattened.

  As yet another example of increasing the strength of the flexible substrate, an SUS or Al base material having a thickness of 20 to 30 μm is used as the base material, and an insulating layer (insulation between the electrode and the base material) is formed on the surface. A diluted polyimide material of about 5 μm is coated with a roll coater. Then, this polyimide is pre-baked, for example, at 150 ° C. for 30 minutes, and post-baked at 350 ° C. for 60 minutes to form a thin-layer polyimide film, which is used as a support substrate.

  Then, after performing plasma treatment and primer treatment for improving adhesion, Ni—Cr is deposited as a thin electrode layer to a thickness of 0.1 to 0.2 μm, and the fine pattern electrode of several tens of μm is formed by photolithography and etching. Form. Furthermore, a flexible transport member can be obtained by forming a surface protective layer such as SiO2, BaTiO2, or TiO2 on the surface to a thickness of about 0.5 to 1 [mu] m. Further, an organic material such as polycarbonate may be coated on SiO 2 or the like. It is also possible to select zirconia or a material generally used as a coating material for a carrier of a two-component developer, for example, a silicone resin.

The characteristics of the present embodiment will be described below for the developing device having the above-described configuration.
FIG. 5 is a schematic diagram for explaining the configuration of a developing device to which one of the features of this embodiment is applied.
In the drawing, the developing device 4 includes a seal member 45 for preventing the developer from scattering from the developer accommodating portion at a position where the developer that has passed through the developing region enters the developing device 4 forming the developer accommodating portion. Is provided. That is, the seal member 45 has a function of sealing the inside and outside of the developing device 4 provided with the developer accommodating portion.

In the embodiment shown in FIG. 5, the seal member 45 is not in contact with the surface of the flare roller 40 used as a developer carrier, but is set with a facing gap G having a predetermined dimension.
The facing gap G is set on condition that the developer in the cloud state is not hindered from moving.
As shown in FIG. 6, the seal member 45 has a wall surface that can be set as a seal range H from the region facing the flare roller 40 to the region facing the supply roller 41 with the above-described facing gap G.
In this case, the facing gap G is set to 0.5 to 3.0 mm when the target flying height of the developer to be hopped on the flare roller 40 is 0.2 mm, and is constant within the above-described seal range H. It is said that. Hereinafter, the opposing gap may be referred to as a gap.

  A first feature of the developing device 4 is that, as shown in FIG. 6, a ventilation portion 45 </ b> A capable of communicating the inside and outside of the developer accommodating portion is provided in a part of the wall surface constituting the above-described seal range H. .

In FIG. 6A, the ventilation portion 45A has an opening on the rear side from the position where the developer that has passed through the developing region on the wall surface facing the gap facing the flare roller 40 enters the gap, and A vent hole having an opening at a position facing the outside and communicating between both openings is used.
As shown in FIG. 6 (B), the ventilation portion 45A is a venting portion having a slit-like opening that faces almost the entire axial direction of the developer carrying surface of the flare roller 40 (shown by an arrow F in the figure). Indicating the air direction). The opening width of the ventilation portion 45A along the rotation direction of the flare roller 40 is set to a size according to the setting of the ventilation capability.

The ventilation portion 45A is for maintaining a pressure in the gap that does not inhibit the developer after development from moving toward the developer accommodating portion. Specifically, after passing through the development area, when the developer moving with the rotation of the flare roller 40 moves, a laminar air flow generated on the upstream side in the movement direction of the developer is caused by the pressure in the gap, particularly In this case, the developer is prevented from being scattered by preventing it from being disturbed by a repulsive force when a pressure that hinders movement is generated.
As a result, the developer that has passed through the development region can smoothly move into the gap without receiving an inadvertent repulsive force when entering the gap.

  That is, the developer that tries to enter the developer accommodating portion after passing through the developing region is in a state where the binding force is weak with respect to the flare roller 40. For this reason, when the pressure in the gap is high, or when the pressure of the repellent airflow generated upstream in the entering direction is strong, there is a possibility that it will be pushed back due to the resistance force when entering. When the developer is pushed back, the developer may be blown out and scattered around the developing region, which may damage the peripheral device.

  Therefore, in the present embodiment, an increase in pressure in the developer accommodating portion is suppressed by evacuation through the ventilation portion 45A, so that inadvertent pressure is not applied to the developer trying to enter the developer accommodating portion. Yes. As a matter of course, the pressure increase in the gap caused by the pressure increase in the developer accommodating portion is also reduced by the exhaust from the ventilation portion 45A to prevent the developer from being ejected. It has become.

In the above-described embodiment, the developer having a weak binding force is attracted to the surface of the flare roller 40 by attracting the developer after passing through the development area in the cloud state to the surface of the flare roller 40. Thus, a configuration is provided to facilitate introduction into the gap described above.
That is, a developer cloud suppressing member made of a conductive member is provided on the side of the seal member 45 where the developer enters, although details are not described.
The developer cloud suppressing member is arranged to face the flare roller 40 from the downstream side of the developing region on the developer inlet side of the seal member 45, and can bias the clouded developer back to the flare roller side. Is applied.
Regarding the bias, an AC bias that is small in the case of a negatively charged developer and large in the case of a positively charged developer with respect to the average potential applied to the internal electrode of the flare roller 40 is suppressed to suppress developer hopping. The developer can be pushed back onto the flare roller surface.

Next, another embodiment of the present invention will be described.
The embodiment shown in FIG. 7 is characterized in that a filter 46 capable of collecting the developer is provided in the ventilation portion 45A shown in FIG.
The filter 46 is loaded in the ventilation part 45A for the entire surface or part of the ventilation part 45A in the opening on the gap side in the ventilation part 45A, and collects the developer that has entered the ventilation part 45A. .

Since the present embodiment is configured as described above, when the developer tries to enter the ventilation portion 45A in accordance with the airflow generated when the developer after passing through the development region enters the gap, By being collected by the filter 46, it is not rebounded in the ventilation part 45A. Thereby, the splashed developer does not blow out from the gap side toward the development area, and it is possible to prevent the peripheral portion from being damaged when it is scattered in the development area.
Further, when there is a developer that has been bounced off and floated without being collected by the filter 46, it is recaptured by the electric field on the flare roller 40 side in a floating state and is recovered by entering the gap again. Thus, the above-described blowing out to the development area is suppressed.

  The above-described filter 46 can be installed in a different manner depending on the vent structure in the vent hole used as the vent portion 45A. For example, when an exhaust duct (not shown) is connected to the vent hole. The filter 46 may be provided not in the ventilation part 45A but in a part of the exhaust duct.

Next, a modified example related to the main configuration of the embodiment shown in FIG. 6 will be described.
FIG. 8 is a view corresponding to FIG. 7 showing a modified example of the configuration of the main part. In FIG. 8, with respect to the gap facing the surface of the flare roller 40 in the seal member 45, the developer after passing through the development region is the developer containing portion. It is characterized by being different between the upstream side and the downstream side in the direction of entering.

That is, the above-described facing gap is set such that the facing gap G1 at the position where the developer begins to enter the gap portion of the seal member 45 facing the flare roller 40 is larger than the facing gap G on the developer accommodating portion side. .
In other words, the developer after passing through the developing region is gradually narrowed from the upstream side toward the downstream side in the moving direction when moving toward the developer accommodating portion, and the opposing gap G at the narrowest position is The size is set so as not to hinder the movement of the developer that is restricted by being clouded.
The opposing gap G at the narrowest position described above is the same as the opposing gap G in the configuration shown in FIG.

  As described above, the gap portion where the flare roller 40 and the seal member 45 face each other is in the range from the position where the developer starts to enter to the facing gap indicated by the reference symbol G1 (the range indicated by the reference symbol H1 in FIG. 7). The opposing gap gradually decreases, and the range of the opposing gap indicated by reference numeral G (the range indicated by reference numeral H in FIG. 7) is set to a constant range.

In the present embodiment, the developer moving through the developing region with the rotation of the flare roller 40 has a large space size of the developer moving path on the seal member 45 side at a position where the developer starts to enter the developer containing portion. Therefore, the developer moving while flying (hopping) can easily enter a space larger than the flying height.
In addition, in the range where the facing gap is large (the range indicated by reference numeral H1), once the developer contacts the surface of the seal member 45, the facing gap gradually decreases, so that the flare roller 40 is brought closer to the flare roller 40 side. Therefore, even if the amount of charge is small and the restraining force is weak, the restrained state is strengthened and the inadvertent scattering to the outside is prevented.

On the other hand, the gap between the seal member 45 and the flare roller 40 is gradually narrowed, that is, made smaller from the entrance side, and the minimum space size is set so as not to hinder the movement of the hopping developer. On the side, collision with the seal member 45 is avoided as described above.
On the other hand, the developer that has passed through the inlet increases in pressure on the downstream side in the movement direction because it is condensed due to a reduction in the space size of the movement path, but the pressure increase causes the pressure to escape from the vent portion 45A. As a result, the rise can be prevented, and the pressure rise on the developer accommodating portion side is suppressed, and the ejection is prevented.
As a result, the developer moving in the facing gap of the seal member 45 does not scatter toward the developing area side, and the occurrence of scumming on the recording material and the contamination of peripheral devices when it scatters can be prevented. become.

Next, another embodiment of the present invention will be described.
FIG. 9 is a view corresponding to FIG. 8 for explaining the present embodiment. In FIG. 9, a plurality of comb teeth are arranged on the surface of the seal member 45 facing the flare roller 40 along the developer moving direction. A groove 45B is provided. The comb-shaped groove 45B has an opening on the flare roller 40 side, and can take in an air flow corresponding to a pressure increase generated in the facing gap.

In the present embodiment, by providing the comb-like groove 45B, the developer movement path corresponding to the facing gap has a labyrinth shape. As a result, air that causes a pressure increase in the opposing gap is taken into the groove 45B, thereby suppressing the pressure increase in the opposing gap.
As a result, it is possible to suppress the developer blow-out and the repulsive pressure on the inlet side of the counter gap caused by the pressure increase caused by the pressure loss in the counter gap.

As described above, in each of the embodiments, since it is configured to suppress the pressure increase in the facing gap provided at the position where the seal member and the flare roller surface face each other, the development at the facing gap entrance side is performed. The influence of the repulsive pressure on the developer and the pressure increase from the inside of the developer container does not affect the movement of the developer.
As a result, the developer after passing through the development area is not scattered to the development area side, and it is possible to reliably prevent the background material from being soiled or the peripheral equipment from being damaged due to this phenomenon.

2 Photosensitive member 4 Developing device 40 Flare roller 41 Supply roller 45 Seal member 45A Ventilation portion 45B Comb-like groove portion G, G1 Opposing gap

Japanese Patent Laid-Open No. 03-21967

Claims (9)

A bias comprising a first electrode and a second electrode provided via an insulator with respect to the first electrode, wherein the potential difference between the first electrode and the second electrode is reversed in time A developing device including a developer carrier that applies a voltage to cloud the developer and conveys the developer to the development area in conjunction with the movement of the electrode,
A development upper seal that seals the inside and outside of the developer container by setting a gap at a predetermined interval with respect to the developer carrier at a position where the developer after passing through the development region enters the developer container. Members are provided,
In the seal member, the gap portion and other positions are arranged at arbitrary positions on the surface from the region where the gap is set and facing the developer carrying member to the region where the inside and outside of the developer container are sealed. A developing device characterized in that a communicating ventilation portion is provided. The developing device according to claim 1,
The ventilation portion is configured by a ventilation hole having one opening on the rear side from the position where the developer that has passed through the developing region enters toward the development upper seal member, and the other opening is located outside the developer containing portion. A developing device. The developing device according to claim 1 or 2,
The developing device according to claim 1, wherein a filter capable of collecting the developer is disposed in a part or the entire area of the ventilation portion. The developing device according to any one of claims 1 to 3,
The seal member has a size as a size of a gap between the developer carrying member and a developer that is constrained by being clouded on the surface of the developer carrying member and does not prevent the developer from moving to the developing region. A developing device characterized by being set to. The developing device according to claim 1,
The seal member has a narrow gap from the upstream side to the downstream side in the moving direction of the developer that moves toward the developer container after passing through the developing region, as the size of the gap between the seal member and the developer carrier. The developing device is characterized in that the gap at the position having the smallest narrowness is set to a size that does not hinder the movement of the developer restrained by being clouded on the surface of the developer carrying member. The developing device according to any one of claims 1 to 5,
2. A developing device according to claim 1, wherein a part of or all of the surface of the seal member facing the developer carrying member is provided with a comb-like groove portion separately from the ventilation portion. An image forming apparatus using the developing device according to claim 1,
2. The image forming apparatus according to claim 1, wherein the developer is charged by friction with a charge imparting member in contact with the developer carrying member. The image forming apparatus according to claim 7.
The developer is visualized by adhering to the electrostatic latent image by electrostatic attraction of the electrostatic latent image formed on the latent image carrier in a clouded state on the surface of the developer carrier. And an image forming apparatus comprising a step of transferring a visible image to a recording material. The image forming apparatus according to claim 7 or 8,
The image forming apparatus, wherein the visible image is sequentially superimposed in an image forming unit capable of forming images of a plurality of colors, and the superimposed image is collectively transferred to the recording material.

Images