JP2007057896A - Developing method and developing device, and image forming apparatus using developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing method and a developing device with which stable removing performance can be attained for a long period of time by removing discharge products etc., formed on an image carrier by improving the flow of a developer, and an image forming apparatus using the developing device. <P>SOLUTION: In the developing method, a developer carrier 2 carries and conveys a two-component developer G containing toner and a magnetic carrier on its surface and an electrostatic latent image on an image carrier is visualized in a development area R opposed to the image carrier 1. The developer G is rubbed against the image carrier 1 in front of the development area and then development using the developer G is carried out in the development area R. Further, the developing device in which the developer carrier 2 carries and conveys the two-component developer G containing the toner and magnetic carrier on its surface and the electrostatic latent image on the image carrier is visualized in the development area R opposed to the image carrier 1 includes a developer flow passage restricting member 3 which rubs the developer G against the surface of the image carrier 1 disposed in front of the development area R for the image carrier 1 and developer carrier 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developing device used in an image forming apparatus such as a copying machine or a printer, and in particular, uses a two-component developer including a toner and a magnetic carrier to develop an electrostatic latent image on an image carrier with toner. The present invention relates to a developing method, a developing device for realizing the developing method, and an improvement of an image forming apparatus using the developing device.

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine or printer, as a method for effectively removing discharge products formed on a photoreceptor by various discharges, for example, a cleaning blade is directly applied to the photoreceptor to remove it. The method is known.
Certainly, the method using a cleaning blade is superior in terms of removing discharge products and residual toner on the photosensitive member, but the blade itself and the photosensitive member are easily damaged by contact with the cleaning blade. It also leads to image defects. Therefore, it becomes difficult to ensure the removal performance of discharge products and the like that are stable over a long period of time.
On the other hand, when the discharge product is removed with a cleaning brush instead of the cleaning blade, the cleaning brush has a long-term stability, but the rubbing force on the surface of the photoreceptor is small, and the discharge product From the point of view of removal, a sufficiently satisfactory result is difficult to obtain.

On the other hand, in order to increase the transfer efficiency of toner to the photoconductor, the photoconductor and the developing roll are rotated in an Against configuration (a configuration in which they move in directions opposite to each other at opposing portions).
Further, in this Against configuration, since the rubbing force to the photoconductor by the magnetic brush can be increased as compared with the With configuration (a configuration in which the opposite portions move in the same direction), the discharge generated on the photoconductor is generated. The removal performance of objects etc. is improved. Therefore, this Gainst configuration is convenient for a method in which cleaning on the photosensitive member is performed without a cleaner.
Furthermore, in the Against configuration, a toner cloud generated when the magnetic brush of the developer contacts the photoconductor is mainly generated on the upstream side of the development area (post-development side of the photoconductor). Therefore, an exposure apparatus that exposes the photoconductor Therefore, it is possible to suppress the toner cloud from adhering to the surface of the film, and to suppress the occurrence of exposure failure.
However, in such an Against configuration, since the magnetic brush having a long ear hits the surface of the photoconductor after development, the toner image formed on the photoconductor after the development is finished with a brush mark (streaks generated on the image). There is a possibility that image defects such as

JP-A-8-305168 (Embodiment of the Invention, FIG. 1) Japanese Patent Laid-Open No. 9-50186 (Embodiment of the Invention, FIG. 1)

Therefore, in order to suppress the occurrence of such brush marks, proposals have been made to reduce the rubbing force of the magnetic brush on the photoconductor by reducing the magnetization and magnetic field strength of the magnetic carrier (for example, Patent Documents). 1 and 2).
However, the method of reducing the rubbing force of the magnetic brush and suppressing the generation of the brush mark in this way cannot sufficiently obtain the removal performance by the magnetic brush of the discharge product formed on the photoreceptor, You can no longer build a cleanerless system.

  The present invention has been made in order to solve the above technical problems, and removes discharge products and the like formed on the image bearing member by devising the flow of the developer, over a long period of time. The present invention provides a developing method, a developing apparatus, and an image forming apparatus using the developing apparatus.

  That is, according to the present invention, as shown in FIG. 1, a two-component developer G containing toner and a magnetic carrier is carried and conveyed on the surface of the developer carrying member 2, and in a developing zone R facing the image carrying member 1 A developing method for visualizing an electrostatic latent image on the image carrier 1, wherein the developer G is rubbed against the image carrier 1 before the development area, and then the developer is developed in the development area R. G development is performed.

In such technical means, the developing method according to the present application is a type using a two-component developer (developer) G, and therefore, toner having various color components can be used. Of course, the present invention can be applied to a developing method used in a monochrome image forming apparatus using the above developing device, and can also be applied to a developing method used in, for example, a full-color image forming apparatus using a plurality of developing devices. Is possible.
If the image carrier 1 and the developer carrier 2 are spaced from each other, the movement direction thereof is the Against direction (moving in a direction opposite to each other), the With direction (at each other). Move in the same direction).
Further, the developer carrier 2 may be any material as long as it can carry and transport the developer G. As a typical aspect, the developer carrier 2 includes a rotatable nonmagnetic sleeve and a magnet body fixedly disposed therein.

  In the present invention, by rubbing the surface of the image carrier 1 with the developer G before the development zone R, it is possible to remove stains such as discharge products formed on the surface of the image carrier 1. Become. Further, since development with the developer G is performed in the subsequent development region R, an image defect such as a brush mark occurs on the toner image surface on the image carrier 1 formed by development. It becomes possible to prevent. Further, by removing the discharge products on the image carrier 1 with the developer G, so-called cleaner-less without a dedicated cleaning member becomes possible.

  In the present invention, in order to realize the above-described developing method, the following may be performed. That is, as shown in FIG. 1, a two-component developer G containing toner and a magnetic carrier is carried and conveyed on the surface of the developer carrier 2, and the image carrier 1 is developed in a development zone R facing the image carrier 1. In the developing device that visualizes the electrostatic latent image on the upper side, the developer G is rubbed against the surface of the image carrier 1 positioned in front of the developing region R between the image carrier 1 and the developer carrier 2. The developer flow path regulating member 3 may be provided.

At this time, the developer flow path regulating member 3 may be configured such that a developer flow path that allows the developer G to rub the image carrier 1 before the development area R is formed. Is not particularly limited.
Further, from the viewpoint of surely rubbing the surface of the image carrier 1 with the developer G by the developer flow path regulating member 3, the image carrier 1 and the developer carrier 2 are preferably in an Against configuration. According to this configuration, the developer G regulated by the developer flow path regulating member 3 can surely rub against the surface of the image carrier 1, and the effect of removing discharge products and the like is further improved.

  Then, from the viewpoint of improving the rubbing force by the developer G, the developer flow path regulating member 3 temporarily accumulates the developer G so that the developer G is rubbed against the image carrier 1, and then the image carrier 1. It is preferable that it is set to be pressed. In this way, by forming the developer reservoir P and pressing the developer G against the surface of the image carrier 1, the rubbing force is improved.

Further, the developer flow path regulating member 3 in the present invention is preferably a roll member. In this case, the flow of the developer G is stabilized by the rotation of the roll member, and the developer pool P is formed in a stable shape. Will be able to. At this time, if a magnetic pole fixedly arranged at a position facing the image carrier 1 inside the roll member is provided, the developer reservoir P can be reliably formed at a position facing the image carrier 1 side. Further, it is possible to effectively utilize the rising of the developer G, and the sliding force of the developer G on the surface of the image carrier 1 can be ensured to be constant. Needless to say, the arrangement of the magnetic poles does not affect the flow of the developer G in the development zone R.
Further, it is preferable that the developer flow path regulating member 3 is rotated by the rotational force of the developer carrying body 2, whereby the rotation of the developer flow path regulating member 3 becomes equal to that of the developer carrying body 2, and development is performed. The conveyance stability of the developer G on the agent carrier 2 can be maintained. Here, “following” means that the developer flow path regulating member 3 and the developer carrier 2 rotate with the developer layer interposed therebetween.
Furthermore, the developer flow path regulating member 3 is preferably locked with the developer carrier 2 by a spring. For example, the developer flow path regulating member 3 is biased between the rotation center axes of each other. Even if the amount of developer between the developer carrying member 2 and the developer carrying member 2 changes, the rotation of the developer flow path regulating member 3 can be further stabilized.

  In the present invention, the developer flow path regulating member 3 can also be a plate-like member. In this case, the developer G can be slid on the surface of the image carrier 1 in front of the development area R by the plate-like member. It is sufficient that the flow path of the developer G is regulated, so that an effective developer pool P can be formed.

In the present invention, the gap between the developer flow path regulating member 3 and the image carrier 1 is preferably set narrower than the gap between the developer carrier 2 and the image carrier 1, and is set in this way. As a result, the developer G, the flow of which has been suppressed by the developer flow path regulating member 3, reliably hits the image carrier 1, and discharge products and the like can be removed from the surface of the image carrier 1.
Further, the gap between the developer flow path regulating member 3 and the developer carrier 2 is set narrower than the gap between the developer carrier 2 and the layer regulating member that regulates the amount of developer on the developer carrier 2. It is preferable that the developer regulated by the layer regulating member does not easily flow out from the gap between the developer flow path regulating member 3 and the developer carrier 2, and the developer pool P is effectively formed. The developer G can be pressed against the image carrier 1.

Furthermore, in the present invention, from the viewpoint of preventing development of the latent image on the image carrier 1 by the developer G pressed against the image carrier 1 by the developer passage restriction member 3, the developer flow passage restriction is performed. It is preferable to apply a non-developable bias to the member 3.
At this time, as the development impossible bias, as shown in FIG. 2, the potential difference Vba between the image portion potential of the electrostatic latent image on the image carrier 1 and the potential of the developer flow path regulating member 3, the image portion potential, If the potential difference Vbd with the developing potential of the developer carrier 2 is set so as to satisfy the relationship of Vba <Vbd, the electrostatic latent image on the image carrier 1 is developed by the developer G in the developer reservoir P. Development can be prevented.
Further, instead of applying the non-developable bias, the developer flow path regulating member 3 may be maintained in a floated state (maintained in an electrically insulated state). It is possible to prevent the image from being developed.

  Furthermore, the present invention is also intended for an image forming apparatus including the developing device described above. Furthermore, the present invention provides a so-called cleaner-less image forming apparatus that includes the developing device described above and an image carrier that carries an electrostatic latent image, and that does not require a dedicated cleaning member on the image carrier 1. The present invention is also intended for image forming apparatuses.

  According to the present invention, in a developing method in which a two-component developer containing a toner and a magnetic carrier is brought into contact with an image carrier and developed, the developer is slid on the image carrier before the development zone. Thereafter, development with a developer is performed in the development area, so that stains such as discharge products formed on the image carrier can be effectively removed and the toner on the image carrier after development can be removed. Image defects on the image surface can be prevented.

In order to embody the above-described developing method, a developer flow path regulating member that slides the developer against the surface of the image carrier positioned in front of the development area between the image carrier and the developer carrier is provided. As a result, stains such as discharge products on the surface of the image carrier can be effectively removed without causing scratches such as brush marks on the developed toner image. Therefore, it is possible to provide a developing device having a stable development performance over a long period of time.
Further, by using this developing device, it is possible to provide an image forming apparatus having a stable developing performance.
Furthermore, a dedicated cleaning member on the image carrier can be eliminated, and a cleanerless image forming apparatus can be provided.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 3 shows Embodiment 1 of an image forming apparatus to which the present invention is applied.
In the figure, the image forming apparatus in the present embodiment is a so-called tandem color image forming apparatus, and each color component (for example, yellow (Y), magenta (M), The photosensitive drums 11 (11a to 11d) on which the cyan (C) and black (K) toner images are formed and supported are arranged on the intermediate transfer belt 20 in parallel.

  Further, around the photosensitive drum 11, a charging device 13 such as a charging roll for charging the photosensitive drum 11, an exposure device 14 including an LED array for forming an electrostatic latent image on the charged photosensitive drum 11, A developing device 12 (12a to 12d) that visualizes the latent image formed on the photoconductive drum 11 with toner, and is provided at a position facing the photoconductive drum 11 and the intermediate transfer belt 20, with the photoconductive body interposed therebetween. A primary transfer device 15 such as a transfer roll for transferring the toner image on the drum 11 onto the intermediate transfer belt 20 is provided.

  The intermediate transfer belt 20 is stretched around three stretching rolls 21 to 23, and circulates and moves in the direction of the arrow in the figure, using the stretching roll 22 as a driving roll, for example. In addition, a belt cleaner 24 for cleaning residual toner on the intermediate transfer belt 20 is disposed on the intermediate transfer belt 20 at a position facing the stretching roll 21 positioned on the upstream side of the photosensitive drum 11 a of the intermediate transfer belt 20. It is provided so that it can be touched and separated.

  Further, in the apparatus main body 10, toner replenishing bottles 16 (16a to 16d) for replenishing the respective color toners to the developing devices 12 (12a to 12d) are provided, and the respective developing devices are connected via communication paths (not shown). 12 can supply toner. For example, in a mode provided with a mechanism for collecting and discharging surplus developer from the developing device 12, a developer including a carrier as appropriate may be used instead of the toner in the toner supply bottle 16. .

In the present embodiment, a paper feed cassette 25 that can supply paper S as a recording material is provided below the apparatus main body 10 so as to be able to be drawn out from the apparatus main body 10. Further, in the vicinity of the paper feed cassette 25, there are provided a pickup roll 26 for picking up the paper S from the paper feed cassette 25, a feed roll 27 and a retard roll 28 which are arranged opposite to the downstream side of the pickup roll 26, Only the uppermost sheet S is picked up by the picked up paper S and is conveyed to a predetermined paper conveyance path.
In addition, on the downstream side thereof, a registration roll 29 is provided that regulates the positioning of the sheet S that has been rolled and conveyed, and on the further downstream side, the toner image that has been primarily transferred onto the intermediate transfer belt 20 is disposed. A secondary transfer device 30 such as a secondary transfer roll that performs batch transfer onto the paper S is provided with the stretching roll 23 as a backup roll.
Further, on the downstream side of the secondary transfer device 30, a fixing device 32 for fixing the toner image transferred onto the paper S is provided, and is constituted by a heating roll 32a and a pressure roll 32b, for example. ing. A discharge roll 31 is provided at the end of the apparatus main body 10 on the downstream side of the fixing device 32 to discharge the fixed sheet S to a discharge tray 10a provided on the casing surface of the apparatus main body 10. Yes.

As shown in FIG. 4, the developing device 12 in the present embodiment stores a two-component developer containing toner and a magnetic carrier in a developing housing 41, and the photosensitive drum 11 is opened in an opening of the developing housing 41. There is provided a mag roll 42 which carries the developer oppositely.
The mag roll 42 of the present embodiment includes a rotatable non-magnetic developing sleeve 42a and a magnet body 42b fixedly disposed inside the developing sleeve 42a and having a plurality of magnetic poles. The developing sleeve 42a is a photosensitive member. The body drum 11 is rotated in the Against direction. The magnet body 42b of the mag roll 42 includes a plurality of magnetic poles (S2, N3, S1, N1, and N2) on the outer peripheral portion thereof, and the magnetic pole S1 is provided at a position facing the photosensitive drum 11, while the magnetic pole 42 A trimmer 43 that regulates the amount of developer on the mag roll 42 is provided at a position facing S2.
Thus, in this embodiment, the magnetic pole N2 of the magnet body 42b is the pickup magnetic pole, the magnetic pole S2 is the trimming magnetic pole, the magnetic pole N3 is the transport magnetic pole, the magnetic pole S1 is the developing magnetic pole, and the magnetic pole N1 and the magnetic pole N2 are repulsive magnetic poles (pick-off magnetic poles). ). In the present embodiment, the arrangement and number of magnetic poles are not limited to this embodiment, and may be appropriately selected.

Further, in the present embodiment, on the front side of the developing area where the mag roll 42 and the photosensitive drum 11 face each other (the side close to the magnetic pole N1 of the mag roll 42), a developer flow path that forms a developer pool at this portion. An auxiliary roll 44 as a regulating member is disposed so as to sandwich the mag roll 42 and the developer.
Furthermore, behind the mag roll 42, a pair of augers 45 (45a, 45b) for agitating and conveying the developer and supplying the developer to the mag roll 42 include, for example, an auger 45a as a supply auger and an auger 45b as an admix auger. It is provided as.

Next, the periphery of the auxiliary roll 44 in the present embodiment will be described in detail with reference to FIG.
In the present embodiment, the auxiliary roll 44 is constituted by a rotatable nonmagnetic sleeve 44a and a magnet body 44b fixedly disposed therein, like the mag roll 42. The magnet body 44b is provided with a magnetic pole on the surface of the photosensitive drum 11, and the counter magnetic pole has no magnetic influence on the magnet body 42b of the mag roll 42.
Further, the central axis of the auxiliary roll 44 and the central axis of the mag roll 42 are locked by a spring (not shown), and even if the developer amount between the mag roll 42 and the auxiliary roll 44 changes, the auxiliary roll 44 can be surely obtained. Is driven to rotate in accordance with the rotation of the mag roll 42.

Further, as shown in FIG. 5, a bias power supply 48 is connected to the auxiliary roll 44, while a bias power supply 47 is connected to the mag roll 42 so that a predetermined developing bias is applied. The bias power sources 47 and 48 make the potential difference between the image portion potential of the photosensitive drum 11 and the bias power source 48 smaller than the potential difference between the image portion potential and the bias power source 47 (applying a development bias). The latent image on the photosensitive drum 11 can be prevented from being visualized by the developer near the auxiliary roll 44.
Furthermore, in the present embodiment, the gap D1 between the photosensitive drum 11 and the mag roll 42 is made wider than the gap D2 between the auxiliary roll 44 and the photosensitive drum 11, so that the developer pool near the auxiliary roll 44 is reduced. It can be formed reliably.

Next, the operation of the developing device 12 in the present embodiment will be described with reference to FIGS. 4 to 6, particularly focusing on the behavior of the developer on the mag roll 42. FIG. 6 is a partially enlarged view of FIG.
The developer G supplied onto the mag roll 42 by the pickup magnetic pole N2 is attracted to the developing sleeve 42a of the mag roll 42 and conveyed. Then, the developer G that has passed through the trimmer 43 is adjusted to a predetermined amount, and reaches the developing area facing the photosensitive drum 11. The toner in the developer G adheres to the latent image on the photosensitive drum 11 and is visualized (developed) as a toner image by the developing bias from the bias power source 47.
The developer G that has passed through the development zone has a small gap D2 between the auxiliary roll 44 and the mag roll 42, and is attracted to the magnetic pole of the auxiliary roll 44, thereby forming a reservoir of the developer G therein. (Α region).

In this α region, the developer G directly hits the photosensitive drum 11 and rubs the surface, and also the rise of the developer due to the magnetic force of the magnetic body 44b of the auxiliary roll 44 helps to discharge the surface of the photosensitive drum 11. Dirt such as products can be more effectively removed. At this time, since the bias power supply 48 applies a non-developable bias to the auxiliary roll 44, the latent image on the photosensitive drum 11 is not unnecessarily developed.
Further, the developer G that has finished removing the discharge products and the like in the α region proceeds to the β region as the auxiliary roll 44 rotates, and is adsorbed again to the mag roll 42 side. The developer G adsorbed by the mag roll 42 is conveyed to the δ region in a state where the bulk density is higher than usual in the gap D2 between the auxiliary roll 44 and the mag roll 42.
On the other hand, a part of the developer G may reach the γ region in the direction opposite to the rotation direction of the auxiliary roll 44, but then is attracted again to the magnetic pole of the mag roll 42 in the δ region.

As described above, in the present embodiment, the developer G can be rubbed against the surface of the photosensitive drum 11 before the developing area of the photosensitive drum 11, and the developer G is strongly applied to this portion. In this case, the developed toner image is not affected because it is a stage before development. Therefore, dirt such as discharge products can be easily removed, and image defects such as brush marks do not occur.
Therefore, a new cleaning member such as a blade is not required, and a stable discharge product removal effect can be maintained even during long-term use. This method is particularly effective in an image forming apparatus oriented to the cleanerless method. Obviously, it may be possible to provide a separate cleaning member such as a cleaning brush on the photosensitive drum 11 instead of being cleanerless.

  In the present embodiment, the rotation direction of the auxiliary roll 44 is the direction that rotates around the mag roll 42. In this case, both the auxiliary roll 44 and the photosensitive drum 11 have an Against configuration, and the sliding force of the developer G in the vicinity of the auxiliary roll 44 is further improved.

  Further, in the present embodiment, an aspect in which a magnetic pole is provided as the auxiliary roll 44 has been described. However, the present invention is not limited to the magnetic pole, and for example, the same applies even if the developer G is electrically attracted and conveyed by connecting a bias power source. It is clear that there is an effect. In this case, it is needless to say that the bias applied by the bias power source is set such that the latent image on the photosensitive drum 11 before the development area is not developed.

  Further, in the present embodiment, the photosensitive drum 11 and the mag roll 42 have an Against configuration. However, for example, both of them have a With configuration (a configuration in which the photosensitive drum 11 and the mag roll 42 move in the same direction at mutually facing portions). By arranging a thin auxiliary roll or the like so that the developer G is applied to the photosensitive drum 11 side, dirt such as discharge products can be removed.

Embodiment 2
FIG. 7 shows a second embodiment of the developing device 12 used in the image forming apparatus to which the present invention is applied. In this figure, the present embodiment is configured in substantially the same manner as the developing device 12 in the first embodiment, except that a plate-like auxiliary member 49 is used instead of the auxiliary roll used in the first embodiment. Different. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and the detailed description is abbreviate | omitted.

In the present embodiment, developer is brought into contact with the photosensitive drum 11 in front of the development area of the photosensitive drum 11 and the mag roll 42 by an auxiliary member 49 that is fixedly arranged.
The periphery of the auxiliary member 49 in the present embodiment will be described in detail with reference to FIG.
In the present embodiment, the auxiliary member 49 is made of a plate-like member having conductivity, such as metal, and is arranged in an arc shape so as to protrude toward the developing area between the photosensitive drum 11 and the mag roll 42. ing. Also in the present embodiment, as in the first embodiment, a bias power supply 48 is connected to the auxiliary member 49, while a bias power supply 47 is connected to the mag roll 42 so that a predetermined developing bias is applied. Yes. These bias power sources 47 and 48 make the potential difference between the image portion potential of the photosensitive drum 11 and the bias power source 48 smaller than the potential difference between the image portion potential and the bias power source 47 (development bias). It is possible to prevent the latent image on 11 from being visualized by the developer in the vicinity of the auxiliary member 49.

  Further, in the present embodiment, the gap D3 between the mag roll 42 and the trimmer 43 is made wider than the gap D4 between the mag roll 42 and the auxiliary member 49, so that a developer reservoir in the vicinity of the auxiliary member 49 is formed reliably. Will be able to.

Next, the operation of the developing device 12 in the present embodiment will be described with reference to FIGS. 7 to 9, particularly focusing on the behavior of the developer on the mag roll 42. FIG. 9 is a partially enlarged view of FIG.
The developer G supplied onto the mag roll 42 by the pickup magnetic pole N2 is attracted to the developing sleeve 42a of the mag roll 42 and conveyed. Then, the developer G that has passed through the trimmer 43 is adjusted to a predetermined amount, and reaches the developing area facing the photosensitive drum 11. The toner in the developer G adheres to the latent image on the photosensitive drum 11 and is visualized (developed) as a toner image by the developing bias from the bias power source 47.
Since the gap D4 between the mag roll 42 and the auxiliary member 49 is smaller than the gap D3 between the mag roll 42 and the trimmer 43, the developer G that has passed through the development zone can be conveyed while adsorbed on the mag roll 42. Instead, the developer G gradually accumulates on the developing region side (β region) of the auxiliary member 49. When this pool gradually expands along the auxiliary member 49 and reaches the α region, the surface of the photosensitive drum 11 is rubbed.

As described above, also in the present embodiment, in the α region, the developer G directly hits the photosensitive drum 11 and rubs the surface, so that dirt such as discharge products on the surface of the photosensitive drum 11 can be removed. At the same time, the latent image on the photosensitive drum 11 is not unnecessarily developed.
Further, the developer G that has rubbed the surface of the photosensitive drum 11 overflows from the auxiliary member 49 and is again adsorbed by the mag roll 42 in the δ region, or from the α region through the gap D 4 between the mag roll 42 and the auxiliary member 49. To reach the area.
As described above, also in the present embodiment, the same developer G pool as that in the first embodiment can be formed, and thus the same effect can be obtained.

In this example, in the configuration of the above-described first and second embodiments, the brush mark generation state and the discharge product removal effect are evaluated and confirmed. In this example, the following four examples were confirmed.
Example 1
In the configuration of Embodiment 1 (using an auxiliary roll), a developer containing a magnetic carrier having a relative permeability of 4.5 was used.
Example 2
In the configuration of the second embodiment (using an auxiliary member), a developer containing a magnetic carrier having a relative permeability of 4.5 was used.
◎ Comparative Example 1
As a conventional example, in order to obtain a normal magnetic brush capable of removing discharge products in an Against configuration and a rubbing force, a developer containing a magnetic carrier having a relative permeability of 4.5 was used.
◎ Comparative Example 2
As another conventional example, a developer containing a magnetic carrier having a relative permeability of 2.9 was used in the same configuration as that of Comparative Example 1 from the viewpoint of further suppressing the generation of brush marks.

In this embodiment, the strength of the magnetic brush is changed by changing the relative permeability of the magnetic carrier. This is due to the following reason.
The rubbing force of the magnetic brush against the photosensitive drum increases as the magnetic translation force of the magnetic brush increases. Further, since this magnetic translation force is proportional to the magnetic dipole moment and the external magnetic field, the external magnetic field may be changed to change the rubbing force, but the external magnetic field is specifically changed. If this is the case, it is necessary to partially change the magnetization of the magnetic poles of the mag roll, and this may affect the flow of the developer itself.
Therefore, in this embodiment, the magnetic dipole moment is changed. Therefore, when the relative permeability is μ, the magnetic dipole moment m is proportional to (μ−1) / (μ + 2). Therefore, in this embodiment, by changing the relative permeability, the rubbing force of the magnetic brush is increased. I changed it.

The evaluation in this example was performed as follows.
For the brush mark, the state of occurrence of scratches on the surface of the solid image (solid image) was visually confirmed and evaluated as the sensor value of the brush mark in the following five stages.
G1: No scratches G2: There are scratches but cannot be confirmed visually G3: There are scratches, but there is no problem in practical use G4: Scratches are visually confirmed and anxious G5: Scratches are very worrisome Become

On the other hand, the discharge product removal amount was evaluated in the following three stages by visually confirming image defects caused by the charging performance of the photosensitive drum.
○: Image defect due to charging performance is not confirmed. Δ: Image defect is confirmed, but there is no practical problem. ×: Image defect occurs at a problem level.

As shown in FIG. 10, in Example 1 and Example 2, good results were obtained in both the brush mark sensory value and the discharge product removal amount.
However, as in Comparative Example 1, when a magnetic brush having a large rubbing force was applied to the surface of the photosensitive drum after the development area, the discharge product could be removed, but the generation of brush marks could not be suppressed. . On the other hand, when the rubbing force was reduced as in Comparative Example 2, although the generation of brush marks was suppressed, it was difficult to remove the discharge products.
From the above, the effectiveness of this case was confirmed.

It is explanatory drawing which shows the outline | summary of the image development apparatus concerning this invention. It is explanatory drawing which shows the electric potential of the developer flow path control member which concerns on this invention. 1 is an explanatory diagram showing Embodiment 1 of an image forming apparatus to which the present invention is applied. FIG. 2 is an explanatory diagram illustrating a developing device according to the first embodiment. FIG. 3 is an explanatory diagram showing a periphery of a development area according to the first embodiment. FIG. 2 is an enlarged view of a main part of the first embodiment. FIG. 10 is an explanatory diagram illustrating a developing device according to a second embodiment. FIG. 10 is an explanatory diagram showing a periphery of a development area according to a second embodiment. FIG. 6 is an enlarged view of a main part of the second embodiment. It is explanatory drawing which shows the result of an Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image carrier, 2 ... Developer carrier, 3 ... Developer flow path regulating member, G ... Developer (two-component developer), R ... Development area, P ... Developer reservoir

Claims (15)

A developing method for carrying and transporting a two-component developer containing toner and a magnetic carrier on the surface of a developer carrying member and visualizing an electrostatic latent image on the image carrying member in a developing area facing the image carrying member Because
A developing method characterized in that a developer is rubbed against an image carrier in front of the developing area, and thereafter development with the developer is performed in the developing area. A developing device that carries and conveys a two-component developer containing toner and a magnetic carrier on the surface of the developer carrying member, and visualizes the electrostatic latent image on the image carrying member in a developing area facing the image carrying member. In
A developing device comprising: a developer flow path regulating member that slidably rubs a developer against the surface of an image carrier positioned in front of a development area between the image carrier and the developer carrier. The developing device according to claim 2, wherein
The developing device, wherein the image carrier and the developer carrier are set to rotate in opposite directions in the development area. The developing device according to claim 2, wherein
The developing device, wherein the developer flow path regulating member is set to temporarily accumulate the developer and press it against the image carrier so that the developer is rubbed against the image carrier. The developing device according to claim 4, wherein the developer flow path regulating member is a roll member. The developing device according to claim 5, wherein
The developing device, wherein the roll member includes at least one magnetic pole fixedly disposed at a position facing the image carrier. The developing device according to claim 4.
The developing device, wherein the developer flow path regulating member is a plate-like member. The developing device according to claim 2, wherein
A developer non-developable bias is applied to the developer flow path regulating member, the potential difference Vba between the image portion of the electrostatic latent image on the image carrier and the bias of the developer flow path regulating member, and the image portion and the developer carrying body A developing device characterized in that a potential difference Vbd from a bias is set so as to satisfy a relationship of Vba <Vbd. The developing device according to claim 2, wherein
The developing device, wherein the developer flow path regulating member is set in a float state without applying a bias. The developing device according to claim 2, wherein
A developing device characterized in that a gap between the developer flow path regulating member and the image carrier is set narrower than a gap between the developer carrier and the image carrier. The developing device according to claim 5, wherein
The developing device, wherein the developer flow path regulating member is rotated by the rotational force of the developer carrying member. The developing device according to claim 5, wherein
The developing device, wherein the developer flow path regulating member is locked by a developer carrier and a spring. The developing device according to claim 7.
The gap between the developer flow path regulating member and the developer carrier is set narrower than the gap between the developer carrier and the layer regulating member that regulates the amount of developer on the developer carrier. Development device. An image carrier for carrying an electrostatic latent image;
An image forming apparatus comprising: the developing device according to claim 2, which develops an electrostatic latent image on the image carrier.   A dedicated cleaning member on an image carrier, comprising: an image carrier that carries an electrostatic latent image; and the developing device according to claim 2 that develops the electrostatic latent image on the image carrier. Forming apparatus that eliminates the need for

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