JP2013114090A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively eliminate an image quality defect of afterimage associated with the phenomenon of transition of an external additive to an image carrier due to continuous production of frame images.SOLUTION: An image forming apparatus comprises, as external-additive temporary collection means 10: a charged collection member 11 whose facing part facing at least the image carrier 1 is composed of a material whose triboelectric series is positioned at a positive side than those of an external additive W and an image carrier 1; a contact part 12 that is provided so as to contact a portion of the charged collection member 11 and a surface of the image carrier 1 and that triboelectrically charges the charged collection member 11 due to contact with the image carrier 1 when the image carrier 1 rotates; and a gap part 13 that has a portion changing so as to gradually become larger as a gap between the facing part of the charged collection member 11 and the image carrier 1 separates from the contact part 12 and that causes an electric field E, based on electric charges generated by triboelectric charging when the charged collection member 11 is triboelectrically charged by the contact part 12, to affect the external additive W on the image carrier 1 to be electrostatically attracted.

Description

  The present invention relates to an image forming apparatus.

For example, those disclosed in Patent Documents 1 and 2 are already known as conventional image forming apparatuses.
Japanese Patent Application Laid-Open No. H10-228688 includes an embodiment provided with a cleaning blade that presses against an image carrier, and externally adds toner to the toner by frictional charging with the image carrier at a position after a cleaning portion by the cleaning blade and before a primary charging portion. A cleaning device for an image forming apparatus is disclosed in which an adsorbing member (scraper or brush roller) charged to a polarity opposite to that of the silica particles is disposed.
In Patent Document 2, a cleaning member that is positively charged and a cleaning member that is negatively charged are placed in contact with a charging roller that is disposed in contact with a photosensitive member, and electrostatic foreign matter recovery is performed along with mechanical recovery. A cleaning device is disclosed.

Japanese Laid-Open Patent Publication No. 3-45779 (Description of Examples, FIG. 2) Japanese Patent Laid-Open No. 6-230657 (Example, FIG. 1)

  The technical problem to be solved by the present invention is an image that can effectively eliminate the afterimage quality defect due to the phenomenon of transition of the external additive to the image carrier caused by continuously producing the surface image. It is to provide a forming apparatus.

  According to a first aspect of the present invention, there is provided a rotatable image holding member for holding an electrostatic latent image, a latent image forming means for forming an electrostatic latent image based on an image signal on the image holding member, toner, A developer holding body that holds and conveys a developer containing an external additive of the same polarity as the carrier and toner is rubbed against the image holding body by the developer held and conveyed by the developer holding body. A developing unit that develops the electrostatic latent image formed on the image holding member by the latent image forming unit, and a transfer that transfers the toner image on the image holding member developed by the developing unit to a transfer medium. And a cleaning member provided on the downstream side in the rotation direction of the image carrier from the transfer portion by the transfer unit and cleaning the post-transfer residue on the image carrier with a cleaning member that contacts the image carrier. And the rotation direction of the image carrier rather than the cleaning part by the cleaning means An external additive temporary recovery means that is provided on the flow side and temporarily recovers the external additive on the image holding body that has passed through the cleaning site, and the external additive temporary recovery means includes the image holding body And at least a portion facing the image carrier is located on the plus side of the external additive and the image carrier with respect to the positive column. Due to contact with the image holding member during rotation of the image holding member, provided to be in contact with the surface of the image holding member. The charge collection member is provided between a contact portion that frictionally charges the member to be charged and an image holding member excluding the contact portion of the member to be charged and the image holding member. The distance between the facing portion of the member and the image carrier is separated from the contact portion. Therefore, when the member to be charged is frictionally charged by the contact portion, an electric field based on the electric charge generated by the frictional charging causes the external additive on the image carrier to move. An image forming apparatus having a gap portion that is allowed to act so as to be capable of electrostatic attraction.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the gap portion is at least downstream of the contact portion in the moving direction of the image holding member and the opposed portion of the charged collection member and the image. An image forming apparatus comprising: a portion that gradually increases as the distance from a holding body increases from the contact portion.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the contact portion of the external additive temporary collecting means extends linearly in a direction crossing the moving direction of the image carrier. The image forming apparatus is characterized in that at least the surface of the image carrier is continuously in contact with the image forming region.
According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, a discharge voltage having a polarity different from the triboelectric charge polarity of the charged collection member is applied to the charged collection member. An external additive discharge means that causes an electric discharge electric field based on the discharge voltage to act between the charged collection member and the image holding member, and discharges the external additive temporarily collected on the charged collection member to the image holding member side. And rotating the image holding body to which the external additive discharged by the external additive discharging means is reattached, and rotating the developer holding body in the developing area of the developing means. And an external additive re-collecting means for returning the external additive reattached by the developer that rubs to the developing means to the developing means.
According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the external additive discharging means is disposed in the non-image forming area interposed between the image forming areas in the moving direction of the image carrier. An image forming apparatus that discharges a collected external additive.
According to a sixth aspect of the present invention, in the image forming apparatus according to the fourth or fifth aspect, the charged collection member of the external additive temporary collection unit includes a collection base material made of a conductive member, and an image of the collection base material. A covering member which is provided so as to cover the surface facing the holding body and is made of a material in which a charged column is positioned on the plus side of the external additive and the image holding body, and discharges the external additive The image forming apparatus is characterized in that a discharge voltage is applied to the recovery substrate.

According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the charge collection member is disposed at a predetermined position via a support member, and the support member is charged. An image forming apparatus comprising an elastic member that elastically presses the collection member toward the image holding member.
According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, the external additive temporary collection means is constituted by a plate-like member extending in a direction crossing the moving direction of the image carrier. And a portion of the plate-like member that faces the image holding member has a flat or curved facing surface, and a portion of the plate-like member that is upstream and downstream in the moving direction of the image holding member. The contact portion that contacts the surface of the image carrier at a position facing away from the end, and the gap formed on the upstream side and the downstream side in the moving direction of the image carrier with the contact portion as a boundary. An image forming apparatus including the image forming apparatus.
According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, the external additive temporary collection means is constituted by a plate-like member extending in a direction crossing the moving direction of the image carrier. And formed on the plate-like member and the charged member having a plurality of convex portions whose heights change in the moving direction of the image carrier at a portion of the plate-like member facing the image carrier. The projecting ends of the plurality of convex portions are provided in contact with the surface of the image holding body, and are provided adjacent to the contact portion, and are formed between the plurality of convex portions and the image holding body. An image forming apparatus comprising the gap portion.

According to the first aspect of the present invention, it is possible to effectively eliminate afterimage quality defects associated with the phenomenon of transfer of the external additive to the image carrier caused by continuously producing the surface image.
According to the second aspect of the present invention, the external additive can be used more efficiently in a state where the electrostatic adhesion force of the external additive on the image holding body to the image holding body is reduced as compared with the aspect without this configuration. Can be temporarily recovered.
According to the third aspect of the present invention, the external additive remaining in the image forming area on the image holding member can be efficiently and temporarily recovered as compared with the aspect without this configuration.
According to the invention of claim 4, the external additive temporarily recovered by the external additive temporary recovery means can be easily recovered again by the developing means, and the external additive can be reused without being wasted. Can do.
According to the fifth aspect of the present invention, the temporarily collected external additive can be efficiently supplied to the developing means via the image carrier without affecting the image forming process, as compared with the aspect without this configuration. The external additive can be quickly recycled for reuse.
According to the sixth aspect of the present invention, compared with the aspect without this configuration, the process of temporarily collecting the external additive and the process of discharging the temporarily collected external additive to the image carrier side are easily realized. Can do.
According to the seventh aspect of the present invention, the contact state of the contact portion between the charged recovery member and the image holding member is kept good with a simple configuration as compared with the aspect without this configuration, and the charged recovery member It is possible to stabilize the triboelectric charging property and improve the temporary recovery performance of the external additive.
According to the invention of claim 8, compared to the aspect without this configuration, the external additive temporary recovery means can be configured with a simple configuration and a wide area for temporarily recovering the external additive can be secured. .
According to the ninth aspect of the present invention, the region for temporarily collecting the external additive can be obtained by devising the shape of the portion of the charged collection member facing the image holding member as compared with the embodiment without this configuration. The external additive temporary recovery means can be easily configured while ensuring a wide range.

(A) is explanatory drawing which shows the outline | summary of embodiment of the image forming apparatus to which this invention was applied, (b) is explanatory drawing which shows the principal part of the external additive temporary collection | recovery means in (a). (A) is explanatory drawing which shows the operation example at the time of external additive temporary collection | recovery in the aspect shown in FIG. 1, (b) is explanatory drawing which shows the operation example at the time of external additive re-recovery in the same aspect. (A) is explanatory drawing which shows an example of the initial image which produces a surface image continuously, (b) is the ghost generation | occurrence | production image produced when producing a surface image continuously using the initial image of (a). It is explanatory drawing which shows an example. It is explanatory drawing which shows typically the factor which the ghost generation | occurrence | production image of FIG.3 (b) produces. FIG. 2 is an explanatory diagram schematically showing an image forming process by the image forming apparatus shown in FIG. 1. 1 is an explanatory diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment. 3 is an explanatory diagram illustrating a configuration of a peripheral portion of the cleaning device of the image forming apparatus used in Embodiment 1. FIG. (A) is explanatory drawing which shows the principal part of the external additive temporary collection | recovery apparatus used in Embodiment 1, (b) is the arrow line view seen from B direction in (a). FIG. 6 is an explanatory diagram illustrating an operation example of the external additive temporary recovery device used in Embodiment 1 during temporary external additive recovery. FIG. 6 is an explanatory diagram illustrating an operation example of the external additive temporary recovery device used in Embodiment 1 when an external additive is discharged. (A) is an explanatory view showing an example of timing for carrying out the external additive discharge process of the external additive temporary recovery device of FIG. 10, and (b) is a re-recovery of the external additive discharged on the photoreceptor to the developing device. It is explanatory drawing which shows operation | movement typically. FIG. 4 is an explanatory diagram illustrating a main part of an image forming apparatus according to a second embodiment. FIG. 10 is an explanatory diagram showing a main part of an external additive temporary recovery device used in a second embodiment. FIG. 10 is an explanatory diagram illustrating an operation example of the external additive temporary recovery device used in the second embodiment during external additive temporary recovery. It is explanatory drawing which shows the ghost level in Example 1 and Comparative Example 1. It is explanatory drawing which shows the relationship between the ghost level in Example 1, and the number of running cycles.

Outline of Embodiment FIG. 1A is a schematic diagram showing an outline of an embodiment of an image forming apparatus to which the present invention is applied.
In the figure, an image forming apparatus includes a rotatable image carrier 1 on which an electrostatic latent image is held, and a latent image forming unit 2 that forms an electrostatic latent image on the image carrier 1 based on an image signal. A developer holding body 3b that holds and conveys the toner, the carrier, and the developer G containing the external additive having the same polarity as the toner, and the developer G held and conveyed by the developer holding body 3b A developing means 3 for developing the electrostatic latent image formed on the image holding body 1 by the latent image forming means 2 by rubbing against the image holding body 1 and the image developed by the developing means 3 A transfer unit 4 that transfers the toner image on the holding body 1 to the transfer medium 5, and is provided on the downstream side in the rotation direction of the image holding body 1 with respect to a transfer portion by the transfer means 4, and contacts the image holding body 1. A cleaning unit 6a for cleaning the post-transfer residue on the image carrier 1 with a cleaning member 6a; Temporary external additive collection that is provided on the downstream side in the rotational direction of the image carrier 1 with respect to the cleaning part by the cleaning means 6 and temporarily collects the external additive W on the image carrier 1 that has passed through the cleaning part. Means 10.
In the present embodiment, the external additive temporary recovery means 10 faces the image carrier 1 and intersects the rotation direction of the image carrier 1 as shown in FIG. A charged collection member 11 that is arranged to extend and at least a facing portion that faces the image carrier 1 is made of the external additive W and a material in which a charged column is positioned on the plus side of the image carrier 1; A part of the charged member 11 is provided so as to come into contact with the surface of the image carrier 1, and the charged member 11 is brought into contact with the image carrier 1 when the image carrier 1 rotates. Between the contact portion 12 that frictionally charges and the image holding body 1 excluding the contact portion 12 of the charged collection member 11 and the image holding body 1, and the charged collection member 11. The distance between the opposing portion of the image carrier 1 and the image carrier 1 is separated from the contact portion 12. Has a portion changing gradually increases As the, the contact portion field E ₁ to be charged collecting member 11 by 12 based on the electric charges generated by the triboelectric charging when it is triboelectrically charged _(see FIG. 2 (a) ) Has a gap portion 13 that allows the external additive W on the image carrier 1 to act to an extent capable of electrostatic attraction.

In such technical means, the image carrier 1 is not limited to a mode in which an electrostatic latent image can be formed by light or ions, such as a photoconductor or a dielectric, but also a latent image corresponding to an electrostatic latent image for each pixel unit. Examples include an image electrode that provides an image potential.
Further, the latent image forming unit 2 may be appropriately selected according to the type of the image carrier 1. For example, if the image carrier 1 is a photoconductor or a dielectric, it may be anything that forms a latent image by light or ions. In an embodiment using pixel electrodes, a latent image potential corresponding to the electrostatic latent image is supplied. Any device that generates a signal may be used. Here, as a representative aspect of the latent image forming means 2 of the former aspect, a charging means 2a for charging the image holding body 1, and light or ions on the image holding body 1 charged by the charging means 2a. And a latent image writing means 2b for writing a latent image.
Further, the developing unit 3 uses a two-component developer to which an external additive (typically silica) having the same polarity as the toner is added as the developer G, and the developer with respect to the image carrier 1. Any developer holding member 3b for rubbing G may be used. However, the developer holder 3b itself may be arranged in contact with the image carrier 1 or may be arranged in a non-contact manner.
Here, as a typical mode of this type of developing means 3, a developing container 3a is provided that contains developer G and opens to face the image carrier 1, and faces the opening of the developing container 3a. The developer holding body 3b is disposed, and the developer container 3a is provided with an agitating and conveying member 3e (for example, a spiral blade member around a rotatable shaft member) in which the developer G can be agitated and conveyed. ) Is provided. The developer holder 3b is typically a rotatable hollow developing rotator 3c, and a magnet member fixedly included in the developing rotator 3c and having a plurality of magnetic poles arranged around it. 3d is used.
Further, the transfer means 4 includes a wide variety of transfer means for transferring the toner image on the image holding member 1 to the transfer medium 5. The transfer system is typically an electrostatic transfer system, but other systems may be used. . The transfer medium 5 here includes not only the recording material which is the final transfer medium, but also includes an intermediate transfer body that holds the toner image intermediately before the recording material.
Further, the cleaning means 6 may be any means that cleans the post-transfer residue on the image carrier 1 with a cleaning member 6a that contacts the surface of the image carrier 1, and as a typical aspect of the cleaning member 6a. Is a plate-like member or brush-like member that scrapes off the residue.

Further, as the external additive temporary recovery means 10, as shown in FIG. 1B, it is only necessary to use a member to be charged 11, a contact portion 12, and a gap portion 13 as constituent elements.
In this example, as the electrified collection member 11, at least the portion facing the image carrier 1 may be made of an external additive W and a material whose charged column is located on the plus side of the image carrier 1. For this reason, the aspect which comprises not only the aspect which comprises the material to which the to-be-charged collection | recovery member 11 is located in a desired charge row | line | column but the material located in the desired charge row | line | column only to the surface layer and coating layer corresponding to the said opposing part Is also included.
Further, the contact portion 12 is provided on a part of the charged collection member 11, and the image holding member 1 is charged so as to charge the charged collection member 11 to a desired polarity (polarity with which the external additive W can be electrostatically attracted). As long as the member to be charged is frictionally charged by bringing it into contact, it may be appropriately selected.
Further, although the gap 13 is provided in a portion excluding the contact portion 12, it is sufficient that the gap 13 has a portion that changes so as to gradually increase as the gap 13 moves away from the contact portion 12. Here, the electric field generated in the gap 13 is divided into the distance between the charged collection member 11 and the image carrier 1 that are frictionally charged, and the charge generated in the charged collection member 11 due to frictional charging. Therefore, the electric field strength may be selected so that the external additive W on the image holding member 1 is electrostatically attracted to the charged collection member 11 side.
In particular, in this example, the gap portion 13 has a portion that gradually increases as the distance from the contact portion 12 increases, so that a narrow gap portion 13 is secured in the vicinity of the contact portion 12. Thus, the electric field strength in the gap portion 13 is not uniform, and the electric field strength acts strongly in the vicinity of the contact portion 12. For this reason, the external additive W on the image carrier 1 is temporarily collected in a concentrated manner on the opposite portion of the charged collection member 11 corresponding to the gap portion 13 in the vicinity of the contact portion 12.

Here, before describing the operation of the image forming apparatus according to the embodiment shown in FIGS. 1A and 1B, an image forming apparatus according to a comparative embodiment (a mode in which the external additive temporary collecting means 10 is not provided). Will be described.
-Outline of operation of image forming apparatus according to comparative mode-
For example, in an image forming apparatus according to a comparative embodiment, for example, a continuous surface image (typically, a so-called solid image with an image density of 100% is mentioned, but the present invention is not limited to this, and the image density is determined in advance. When a high image density (for example, 80% or more) is formed for each turn of the image carrier 1 for a predetermined number of times or more, the image including the area where the surface image is formed is formed. For example, when a halftone image is formed in an image region, a phenomenon in which a continuous surface image appears as an afterimage (ghost) can occur with a relatively high probability. Such an afterimage phenomenon appears remarkably in a halftone image, but may also appear in the background (non-image portion).
For example, as shown in FIG. 3A, an example in which a part of the area of the continuous surface image IM ₁ is deleted as the initial image and a halftone image IM ₂ is present instead of this is shown. When the plane image IM ₁ is repeated a predetermined number of times or more, as shown in FIG. 3B, in the region of the halftone image IM ₂ that overlaps the continuous plane image IM ₁ , the original image of high continuous residual image (ghost image) of the surface image IM ₁ possibly IMg appears.
Such a situation occurs when, for example, the circumference of the image carrier 1 is shorter than the length along the moving direction of the image carrier 1 of the initial image (see FIG. 3A) or vice versa. When the initial image (IM ₁ + IM ₂ ) is continuously formed through a predetermined inter-image area instead of the circulation unit of the body 1, the continuous surface image IM ₁ during one rotation of the image carrier _1. situation in which the imaged region of overlap with the imaged region of the halftone image IM ₂ is likely to occur remarkably.

In such a situation, the cause of the above-mentioned afterimage phenomenon is estimated as follows.
That is, as shown in FIG. 4, if an external additive W of toner T adheres to the image carrier 1 when a continuous surface image is produced, the normal image carrier 1 has a cleaning means. 6 is often provided. Here, although the cleaning member 6a (for example, a plate-like cleaning member) of the cleaning means 6 is excellent in the ability to clean the toner T, it can be said that it is not necessarily excellent in the ability to remove the external additive W of the toner T. Absent. Since the external additive W added to the surface of the toner T has a small particle size, the cleaning member 6a may slip through the cleaning member 6a when the scraping force of the cleaning member 6a is low.
Silica is often used as a representative of this type of external additive W, and since it has excellent functions as an external additive W such as chargeability and transferability, almost all of the products currently used in products are used. Externally added to the toner T. However, the silica detached from the toner T and the silica originally released from the toner T while being agitated and conveyed by the agitating / conveying member 3e in the developing container 3a of the developing means 3 migrates to the surface of the image carrier 1. Easy to adhere.
Since the silica as the external additive W transferred to the image carrier 1 has a small particle size and is relatively firmly attached, it cannot be scraped off by the scraping force of the cleaning member 6a, and the cleaning member 6a. Passes through the cleaning area due to the above, and as the image carrier 1 circulates, it again reaches the developing area of the developing means 3.
At this time, the image carrier 1 is charged to a predetermined charging potential Vh by the latent image forming means 2 (in this example, charging means 2a + latent image writing means 2b) (e in the figure is a negative charged charge). ), An electrostatic latent image Z is formed, so that the silica as the external additive W that has passed through the cleaning member 6a is given a negative charge e when passing through the charging means 2a of the latent image forming means 2. However, since the silica charged by the charge application is removed by the rubbing force (scavenging force) by the developer G in the developing region of the developing unit 3, the surface potential of the image carrier 1 changes. A phenomenon occurs. Specifically, the latent image potential Vz relating to the site where the silica has been scraped is likely to be in a state where the absolute value of the latent image potential Vz is further lowered by ΔV.
In this state, when a developing operation is performed by applying a developing voltage Vbias (| Vh |> | Vbias |> | Vz |) to the developer holding body 3b of the developing unit 3, the electrostatic latent image Z More toner T than the surroundings is developed in the portion where the silica has been scraped off, resulting in a ghost image IMg (FIG. 3B), which is an afterimage having a different density from the other portions.
In particular, in the case where the surface images are continuously formed, since the images are repeatedly formed on the same portion of the image carrier 1, the charged silica accumulates, and the generation of the ghost image IMg is remarkable. .
Further, in a mode in which a charging member that is in contact with the image carrier 1 is used as the charging unit 2a, the silica that has passed through the cleaning member 6a adheres to the charging member of the charging unit 2a and causes a charging failure. There is also a concern that image quality is likely to deteriorate.
The afterimage (ghost) phenomenon described above is mainly caused by an increase in the amount of silica transferred to the image carrier 1 with a large development amount when a high-density image is continuously formed. However, if the total amount of charges of the slipped silica is large, an afterimage (ghost) phenomenon may appear even if it is not a high-density image.

-Outline of operation of image forming apparatus according to embodiment-
In contrast, in the image forming apparatus according to the embodiment shown in FIGS. 1A and 1B, as shown in FIGS. 2A and 5, the external additive W (attached to the image carrier 1 ( For example, if silica) passes through the cleaning member 6 a of the cleaning unit 6, the external additive W that has passed through the cleaning member 6 a passes through the external additive temporary recovery unit 10 before passing through the latent image forming unit 2.
At this time, the external additive temporary recovery means 10 arranges the charged recovery member 11 with respect to the image carrier 1 via the contact portion 12 (corresponding to the area A in FIG. 2A), and the contact portion 12. A gap 13 is provided between the opposite surface of the image carrier 1 of the charged collection member 11 and the image carrier 1, and in particular, the gap 13 has a gap between the charged collection member 11 and the image carrier 1. It has a portion (corresponding to a region B in FIG. 2A) that gradually increases as the distance from the contact portion 12 increases.
In such a configuration, when the charged collection member 11 comes into contact with the image carrier 1 through the contact portion 12, the charged collection member 11 is charged due to the relationship between the image carrier 1, the external additive W, and the charged collection member 11. The collection member 11 is frictionally charged. As a result, a charge having a predetermined polarity is generated in the charged collection member 11, and the external additive W on the image carrier 1 is applied to the gap 13 by the generated charge. An electric field E ₁ that can be electrostatically attracted acts.
In particular, in the vicinity of the contact portion 12 in the gap portion 13, a portion (corresponding to a region B in FIG. 2A) is provided so that the interval gradually increases as the distance from the contact portion 12 increases. The electric field strength in the region B is strong, and the external additive W adhering to the image carrier 1 is electrostatically directed toward the charged member 11 by the action of the electric field E _{1 in} the region B described above in the gap portion 13. Sucked and temporarily collected by the charged collection member 11.
As a result, the external additive W that has passed through the cleaning member 6a hardly passes through the charging unit 2a of the latent image forming unit 2, and a negative charge e is applied to the external additive W, so that the developing region of the developing unit 3 is exposed. Never reach. For this reason, there is almost no phenomenon that the external additive W charged by the charge application is removed by the rubbing force (scavenging force) by the developer G in the developing region of the developing means 3, and accompanying the removal of the charged external additive W. There is almost no phenomenon that the surface potential of the image carrier 1 changes. Therefore, for example, the latent image potential Vz of the electrostatic latent image Z corresponding to the halftone image is hardly lowered, and the electrostatic latent image Z is developed as a substantially uniform halftone image.
In the present embodiment, even when the charging member 2a uses a charging member that contacts the image carrier 1, the external additive W attached to the image carrier 1 adheres to the charging member. Hardly occurs.

Next, a typical aspect or a preferable aspect in the present embodiment will be described.
First, as a preferable aspect of the gap portion 13 of the external additive temporary recovery means 10, at least the downstream side in the moving direction of the image carrier 1 with respect to the contact portion 12, the opposing portion of the charged collection member 11 and the image carrier 1. And having a portion that gradually increases as the distance from the contact portion 12 increases.
In this embodiment, after the external additive W on the image carrier 1 passes through the contact portion 12, it passes through the gap portion 13 where the interval gradually increases as the distance from the contact portion 12 increases. At this time, the external additive W on the image carrier 1 receives a force acting in the shearing direction when passing through the contact portion 12, and the external additive W slightly moves. It is presumed that the adhesive force with the agent W is weakened, and it is likely to be electrostatically attracted to the charged collection member 11 at the gap portion 13 having a high electric field strength immediately after passing through the contact portion 12.
Further, as a typical mode of the contact portion 12, the contact portion 12 extends linearly in a direction crossing the moving direction of the image carrier 1, and continuously at least within the range of the image forming region on the surface of the image carrier 1. The aspect which is contacting is mentioned.
In this embodiment, a narrow gap 13 is continuously secured in the vicinity of the contact 12 that continuously extends at least within the range of the image forming area of the image carrier 1, and an electric field based on electric charge is generated in the narrow gap 13. Since a strong electric field acts, it is preferable in that the external additive W mainly remaining in the image forming region on the image carrier 1 is efficiently and temporarily collected on the charged collection member 11 side.

Further, as a typical mode of reusing the external additive W temporarily collected in the external additive temporary collection means 10, as shown in FIGS. A discharge voltage Vt (see FIG. 2B) having a polarity different from the frictional charging polarity of the charged collection member 11 is applied to the collection member 11, and the discharge voltage between the charged collection member 11 and the image carrier 1 is applied. by the action of the discharge electric field E ₂ based on vt, the external additive ejection means 15 for ejecting the external additive W which is temporarily collected in the charging recovery member 11 to the image carrier 1 side, the external additive discharge means The image carrier 1 to which the external additive W ejected in 15 is reattached is rotated, and the developer carrier 3b is rotated in the developing area of the developing means 3 so that the image carrier 1 is rubbed. And an external additive re-recovery means 16 for returning the external additive W reattached by the developing agent G to the developing means 3. Can be mentioned.
Here, the external additive discharging means 15 may be any device that applies a discharge electric field between the member to be charged 11 and the image carrier 1 and discharges the temporarily collected external additive W to the image carrier 1 side. Good.
Further, the external additive re-collecting means 16 rotates the image carrier 1 to convey the external additive W reattached to the image carrier 1 to the development area of the developing means 3 and holds the developer in the developing means 3. If the image carrier 1 is rubbed with the developer G held on the developer holding body 3b by rotating the body 3b, the external additive W reattached to the image holding body 1 is scraped with the developer G. Then, it is collected again in the developing container 3a.
In this embodiment, a preferred embodiment of the external additive discharge means 15 is an embodiment in which the external additive W temporarily recovered is discharged to a non-image forming area interposed between the image forming areas with respect to the moving direction of the image carrier 1. Can be mentioned.
In this aspect, the discharge area of the external additive W is a non-image forming area, and the discharge process of the external additive W can be performed in parallel with the image forming process. Here, it can be realized even if the discharge region of the external additive W is an arbitrary region of the image carrier 1, but in this case, the external additive temporarily collected by the external additive temporary collection means 10 After the additive W is discharged onto the image carrier 1, the image carrier 1 cannot be subjected to image forming processing while the external additive W is moved to the development area of the developing means 3. .

Further, as an aspect effective in adding the external additive discharge means 15, the charged collection member 11 of the external additive temporary collection means 10 includes a collection substrate 11a made of a conductive member, and this collection substrate 11a. A covering member 11b which is provided so as to cover the surface facing the image carrier 1 and is made of a material in which the charged column is located on the plus side of the external additive W and the image carrier 1; The external additive discharge means 15 may include a mode in which the discharge voltage Vt is applied to the recovery base material 11a.
In this embodiment, the charged collection member 11 is frictionally charged by contact with the image carrier 1 and the discharge voltage Vt having the opposite polarity to the frictional charge polarity is applied from the external additive discharge means 15. In order to satisfy both requirements, the recovery base 11a made of a conductive member and the covering member 11b capable of friction charging are functionally separated.
Further, as a preferable support structure of the charged collection member 11, the charged collection member 11 is disposed at a predetermined position via a support member (not shown), and the support member holds the image of the charged collection member 11. The aspect comprised by the elastic member elastically pressed to the body 1 side is mentioned.
Here, since the to-be-charged recovery member 11 needs to be placed in contact with the image carrier 1 via the contact portion 12, it is preferably pressed to the image carrier 1 side by a pressing member. In this case, the to-be-charged recovery member 11 may be supported in a floatable manner and pressed by a dedicated pressing member. However, from the viewpoint of simplifying the support structure, the support member is elastic as in this embodiment. The aspect which can be supported simultaneously in the state comprised by the member and pressed is preferable.

Moreover, the following are mentioned as a typical aspect of the external additive temporary collection | recovery means 10. FIG.
As shown in FIG. 1 (b), the first representative embodiment is composed of a plate-like member extending in a direction intersecting the moving direction of the image carrier 1, and the image carrier 1 of the plate-like member. An image of the charged recovery member 11 having a flat or curved opposing surface at the opposing portion, and the opposing surfaces at positions away from the upstream and downstream ends of the image carrier 1 in the movement direction of the plate member. A contact portion 12 that is brought into contact with the surface of the holding body 1 and a gap portion 13 that is formed on the upstream side and the downstream side in the moving direction of the image holding body 1 with the contact portion 12 as a boundary.
In this embodiment, a plate-shaped member having a simple shape is used as the charged collection member 11, and the gap portions 13 are secured on the upstream side and the downstream side in the moving direction of the image carrier 1 with the contact portion 12 as a boundary.
Unlike the first representative embodiment shown in FIG. 1B, the second representative embodiment is composed of a plate-like member extending in a direction crossing the moving direction of the image carrier 1, and the plate-like member. Formed on the plate-like member, and a member to be charged 11 having a plurality of convex portions (not shown) whose height changes in the moving direction of the image carrier 1 at a portion facing the image carrier 1. Further, a contact portion 12 that makes the protruding ends of the plurality of convex portions come into contact with the surface of the image holding body 1, and a plurality of protrusions that are provided adjacent to the contact portion 12 and formed between the plurality of convex portions and the image holding body 1 And a gap portion 13.
In this aspect, as the member to be charged 11, a plate-like member having a plurality of convex portions at a portion facing the image carrier 1 is used. The contact portion 12 is obtained by bringing the protruding ends of the plurality of convex portions into contact with the surface of the image carrier 1. Further, the plurality of gap portions 13 are obtained between the plurality of convex portions and the image carrier 1.

Hereinafter, the present invention will be described in more detail based on embodiments shown in the accompanying drawings.
Embodiment 1
-Overall configuration of image forming apparatus-
FIG. 6 is an overall configuration diagram of Embodiment 1 of the image forming apparatus to which the present invention is applied.
In this figure, this image forming apparatus 20 is a quadruple tandem full-color image forming apparatus, and has a plurality of color components (in this example, yellow (Y), magenta (M), cyan (C), black (K)). The image forming units 30 (specifically, 30Y, 30M, 30C, and 30K) as image forming units capable of outputting the images are arranged side by side at predetermined intervals in the order of image formation, and face each image forming unit 30. An intermediate transfer body 40 capable of temporarily holding an image formed by each image forming unit 30 is disposed at the site, and the image held on the intermediate transfer body 40 is recorded by a batch transfer device 50. After batch transfer to P, the fixing device 60 fixes the image transferred onto the recording material P. Reference numeral 70 denotes a recording material conveyance system for conveying the recording material P to the batch transfer portion.

<Image forming unit>
Each of the image forming units 30 (30Y to 30K) includes a drum-shaped photoreceptor 31 as an image carrier having a photoreceptor layer on the surface, a charging device 32 that uniformly charges the photoreceptor 31, and a uniform An exposure device 33 that forms an electrostatic latent image by irradiating the charged photoreceptor 31 with image light, and a toner image (image) by transferring toner to the electrostatic latent image formed on the photoreceptor 31. A developing device 34, a cleaning device 36 for cleaning toner remaining on the photoconductor 31 after primary transfer of the toner image on the photoconductor 31 to the intermediate transfer body 40, and a rotation direction of the photoconductor 31 relative to the cleaning device 36. An external additive temporary recovery device 37 that is provided on the downstream side and recovers the external additive remaining on the photosensitive member 31 that has passed through the cleaning device 36;
In this example, in the image forming unit 30, the photosensitive member 31, the charging device 32, the developing device 34, the cleaning device 36, and the external additive temporary recovery device 37 are configured as a process cartridge that is integrated in advance. The process cartridge is detachably attached to the housing of the image forming apparatus in order to be replaceable for each color component.
Here, the photoreceptor 31 is obtained by laminating and forming a photosensitive layer on a conductive metal base having a diameter of about 20 to 100 mm, for example. This photosensitive layer is a function-separated type in which a charge generation layer and a charge transport layer are sequentially laminated. Usually, it has a high resistance, but its specific resistance is changed by light irradiation (specifically, it has a low resistance by light irradiation). And has the property of becoming conductive).
As the charging device 32, for example, a scorotron is used, but is not limited to this, and a device using contact or non-contact type charging members such as corotron, various other dischargers, roll shape / blade shape, etc. You can select as appropriate.
As the exposure device 33, a laser scanning device, an LED array, or the like is used.
The developing device 34 has a developing container 34a that opens opposite to the photoreceptor 31 and accommodates a two-component developer, and faces the opening of the developing container 34a, and a developing roll that can hold and convey the developer 34b is disposed. In the developing container 34a, an agitating / conveying member (not shown) capable of agitating and conveying the two-component developer and a layer regulating member (not shown) in which the layer thickness of the developer held on the developing roll 34b is regulated. )) And other functional members are incorporated.
As the developer toner used in this example, for example, toner produced by an emulsion polymerization method can be used, but not limited to this production method, for example, suspension polymerization method, suspension granulation method, It may be produced by a dissolution suspension method, a kneading pulverization method, or the like. Here, the particle size of the toner has a large influence on the image quality, and the smaller the particle size, the better the image quality. However, if the particle size is small, the developability deteriorates and the handling becomes difficult. Is desirable. Further, an appropriate amount of silica or titania having an average particle diameter of about 10 to 150 nm is externally added to the toner as a charge control agent or a transfer aid. In this example, silica having a relatively large particle diameter is externally added in order to ensure particularly cleanability and transfer maintenance. Specifically, silica having a number average particle diameter of about 100 to 150 nm is externally added. The “number average particle diameter” here is determined by a circle equivalent diameter (Heywood diameter) by a microscope method based on JIS Z 8901, and a scanning electron microscope (SEM) was used as the microscope.
The details of the cleaning device 36 and its peripheral configuration will be described later.

<Intermediate transfer member and its peripheral configuration>
The intermediate transfer member 40 is composed of an endless belt member that is circulated and rotated by a plurality of (three in this example) stretching rolls 41 to 43. For example, the intermediate transfer body 40 is a driving roll that can be driven to rotate. Driven, a predetermined tension is applied using the tension roll 42 as a tension adjustment roll.
In this example, the intermediate transfer member 40 has a surface resistivity of 10 by dispersing a substance for imparting conductivity such as carbon or an ion conductive substance in a resin material such as polyimide, polyamideimide, polycarbonate, or fluorine resin. It is formed by adjusting to about ¹⁰ to 10 ¹² Ω / □ (measurement voltage: 100 V).
Also, a primary transfer device 45 is disposed on the back surface of the intermediate transfer body 40 facing the photoconductor 31 of each image forming unit 30. The primary transfer device 45 applies, for example, a predetermined primary transfer voltage. The toner image on each photoconductor 31 is primarily transferred to the intermediate transfer body 40.
Further, an intermediate transfer body cleaning device 46 is disposed in a portion of the intermediate transfer body 40 that faces the stretching roll 41. The intermediate transfer body cleaning device 46 is, for example, a plate-like shape that contacts the surface of the intermediate transfer body 40. The residual toner on the intermediate transfer body 40 is cleaned.

<Batch transfer device>
The batch transfer device 50 has a secondary transfer roll 51 on the surface of the intermediate transfer body 40 facing the stretch roll 43 of the intermediate transfer body 40, and the stretch roll 43 facing the secondary transfer roll 51 is connected to the counter electrode. Also used as a roll, by applying a secondary transfer voltage to the stretching roll 43 or the secondary transfer roll 51, a transfer electric field is generated in the transfer area between both rolls, and the recording material P conveyed by the transfer electric field is applied to the recording material P On the other hand, the toner image on the intermediate transfer body 40 is transferred collectively (secondary transfer).
<Fixing device>
The fixing device 60 may be appropriately selected as long as it can transfer an unfixed toner image on the recording material P. For example, a heating fixing roll 61 including a heating source and the recording material between the heating fixing roll 61 and the fixing device 60 may be selected. An embodiment having a pressure fixing roll 62 that is arranged to press and convey P and rolls together with the heat fixing roll 61 is exemplified.
<Recording material conveyance system>
The recording material conveyance system 70 includes a recording material accommodation device 71 in which the recording material P is accommodated so that it can be sent out for each sheet. The recording material P delivered from the recording material accommodation device 71 is conveyed along the conveyance path 72. In the transport path 72, an alignment roll 73 for aligning the supply timing of the recording material P to the batch transfer site is disposed before the batch transfer site, and from the batch transfer site in the transport path 72. In addition, by disposing a conveyance belt 74 on the downstream side in the conveyance direction of the recording material P, the recording material P after batch transfer is conveyed toward the fixing device 60, and a discharge roll 75 is disposed immediately after the fixing device 60. Thus, the recording material P is discharged toward a recording material discharge receiver (not shown).

-Basic image forming operation of image forming device-
A basic image forming operation of the image forming apparatus according to the present embodiment will be described.
In each image forming unit 30 (30Y to 30K), each color component image is formed on the photoreceptor 31.
Hereinafter, an operation of forming a yellow image in the image forming unit 30Y will be described.
First, prior to the operation, the surface of the photoreceptor 31 is charged to a predetermined potential (for example, a potential of about −600 V to −800 V) by the charging device 32. Thereafter, a light beam such as a laser beam is output from the exposure device 33 to the surface of the charged photoreceptor 31 according to the yellow image data sent from a control unit (not shown). This light beam is applied to the photosensitive layer on the surface of the photoconductor 31, whereby an electrostatic latent image of a yellow print pattern is formed on the surface of the photoconductor 31. The electrostatic latent image here is an image formed on the surface of the charged photoconductor 31, and the specific resistance of the irradiated portion of the photosensitive layer is lowered by the light beam, and the charged charge on the surface of the photoconductor 31. On the other hand, it is a so-called negative latent image formed by the charge remaining in the portion not irradiated with the light beam.
The electrostatic latent image formed on the photoconductor 31 in this way is rotated to a predetermined development position by the rotation of the photoconductor 31. At this development position, the electrostatic latent image on the photoconductor 31 is converted into a visible image (toner image) by the developing device 34. In the developing device 34, for example, yellow toner having an average particle diameter of 3 to 8 [mu] m manufactured by an emulsion polymerization method is accommodated. The yellow toner is frictionally charged by being agitated inside the developing device 34 and has the same polarity (−) as the charged charge on the surface of the photoreceptor 31. As the surface of the photosensitive member 31 passes through the developing device 34, the yellow toner is electrostatically attached only to the latent image portion on the surface of the photosensitive member 31, and the electrostatic latent image is developed by the yellow toner. The The photoconductor 31 continues to rotate, and the yellow toner image developed on the surface of the photoconductor 31 is conveyed to a predetermined primary transfer position. When the yellow toner image on the surface of the photoconductor 31 is conveyed to the primary transfer position, a predetermined primary transfer voltage is applied to the primary transfer device 45 (primary transfer roll in this example), and the photoconductor 31 moves toward the primary transfer device 45. The electrostatic force acts on the toner image, and the toner image on the surface of the photoreceptor 31 is transferred to the surface of the intermediate transfer member 40.
At this time, the applied primary transfer voltage is a (+) polarity opposite to the polarity (−) of the toner. For example, in the image forming unit 30Y, a constant current control is performed to about +20 to 30 μA by a control unit (not shown). Has been. On the other hand, the transfer residual toner on the surface of the photoreceptor 31 is cleaned by the cleaning device 36.

Further, the primary transfer voltage applied to the primary transfer device 45 subsequent to the second image forming unit 30M after the first image forming unit 30Y is controlled in the same manner as described above. Thus, the intermediate transfer body 40 to which the yellow toner image has been transferred by the first image forming unit 30Y is sequentially conveyed through the second to fourth image forming units 30M, 30C, and 30K, and the toner images of the respective colors are similarly formed. Overlaid and multiple transferred. The intermediate transfer member 40 on which the toner images of all colors are transferred in multiple numbers through the first to fourth image forming units 30 (30Y to 30K) is conveyed in the direction of the arrow and is opposed to the inner surface of the intermediate transfer member 40. 43 and a secondary transfer roll 51 arranged on the image holding surface side of the intermediate transfer body 40.
On the other hand, the recording material P is supplied at a predetermined timing after the recording material P is aligned to the batch transfer portion by the alignment roller 73 via the recording material conveyance system 70, and a predetermined secondary transfer voltage is applied to the secondary transfer roll, for example. 51 is applied. The secondary transfer voltage applied at this time is a (+) polarity opposite to the polarity (−) of the toner, and an electrostatic force from the intermediate transfer body 40 toward the recording material P acts on the toner image, and the intermediate transfer body. The toner image on the surface 40 is transferred to the surface of the recording material P. In this example, the secondary transfer voltage is determined according to the resistance detected by a resistance detection means (not shown) for detecting the resistance of the batch transfer site, and is controlled by a constant voltage.
Thereafter, the recording material P is sent to the fixing device 60, the toner image is heated and pressurized, and the color-superposed toner image is melted and fixed on the surface of the recording material P. Thus, the recording material P on which the fixing of the color image has been completed is carried out toward a recording material discharge receiver (not shown), and a series of color image forming operations is completed. The residual toner on the intermediate transfer member 40 is cleaned by the intermediate transfer member cleaning device 46.

Next, the cleaning device 36 and its peripheral configuration will be described in detail.
-Cleaning device and its peripheral configuration-
FIG. 7 is an explanatory view showing the cleaning device 36 and its peripheral configuration.
<Cleaning device>
In the figure, the cleaning device 36 has a cleaning container 81 that is disposed in the vicinity of the photoconductor 31 and opens on the side facing the photoconductor 31, and the rotation of the photoconductor 31 out of the opening edge of the cleaning container 81. A cleaning blade 82 is provided at a position (on the upper edge of the opening in FIG. 7) located on the downstream side in the direction.
Here, the cleaning blade 82 is a cleaning member formed in a plate shape with a predetermined thickness by an elastic material, and the material of the cleaning blade 82 is excellent in mechanical properties such as wear resistance, chipping resistance, and creep resistance. For example, thermosetting polyurethane rubber is used, but is not limited thereto, and functional rubber materials such as silicone rubber, fluorine rubber, ethylene / propylene / diene rubber may be widely used. In addition, as a mounting structure of the cleaning blade 82, a support bracket 83 made of a sheet metal having a substantially L-shaped cross section is fixed to the upper edge of the opening of the cleaning container 81 with a stopper 84 such as a screw. The base of the cleaning blade 82 is bonded to the surface facing the body 31, and the protruding portion protruding from the bonded portion of the cleaning blade 82 is extended in a direction against the rotation direction of the photosensitive member 31, and the leading edge of the protruding portion For example, the contact portion may be in contact with the surface of the photoreceptor 31. In this example, the pressing method of the cleaning blade 82 employs a constant displacement method (a method of displacing the tip edge portion of the cleaning blade 82 by a predetermined amount) with a simple structure and low cost. A predetermined pressure is obtained based on the elastic coefficient of the blade 82 and the amount of displacement thereof. However, the pressurization method of the cleaning blade 82 is not limited to the constant displacement method, and for example, a constant load method in which the contact pressure hardly changes with time may be used.
Further, a seal member 85 is fixed to a portion (the lower edge of the opening in FIG. 6) of the opening edge of the cleaning container 81 located on the upstream side in the rotation direction of the photosensitive member 31. The seal member 85 is made of a resin film having flexibility (for example, a thermoplastic polyurethane film having a thickness of 0.1 mm) or the like, and the protruding portion that protrudes from the fixed portion extends along the rotation direction of the photoreceptor 31. In this state, it is brought into contact with the photosensitive member 31 in a state of extending in the direction, and the gap between the photosensitive member 31 and the cleaning container 81 is almost closed, and waste toner or the like accommodated in the cleaning container 81 is prevented from leaking outside. .
Further, inside the cleaning container 81, a conveying member 86 for conveying the waste toner accommodated along the axial direction of the photosensitive member 31 is disposed.

In the cleaning device 36 having such a configuration, as shown in FIG. 7, the transfer residual toner T remaining on the surface of the photoconductor 31 passes through the contact portion between the seal member 85 and the photoconductor 31 as it is, and then is cleaned. Scraped by 82. The toner T scraped off by the cleaning blade 82 is once stored in the cleaning container 81, and is finally transported and discharged to the outside of the cleaning container 81 by the transport member 86.
However, in such a cleaning device 36, when the tip of the cleaning blade 82 is worn by rubbing against the photoreceptor 31, or when the coefficient of friction of the surface of the photoreceptor 31 is high, the tip of the cleaning blade 82 is When the blocking force of the toner T is reduced due to irregular deformation, the external additive W having a small particle size is likely to slip through the cleaning blade 82. In particular, the silica used as the external additive W has a small particle size and is firmly attached to the surface of the photoreceptor 31 by van der Waals force or the like, so that it can be completely cleaned with the scraping force by the cleaning blade 82. Therefore, it is easy to slip through the contact portion between the cleaning blade 82 and the photosensitive member 31.

<External additive temporary recovery device>
Among such slipping-out phenomena of the external additive W, especially silica has a relatively large particle size, and as described above, there is a concern that a ghost image is generated during continuous printing or that the image quality is likely to be deteriorated. There is an external additive temporary recovery device 37 from the viewpoint of avoiding this.
As shown in FIGS. 7 and 8A and 8B, the external additive temporary recovery device 37 has a support base 110 having a substantially J-shaped cross section disposed along the axial direction of the photosensitive member 31, for example. The support portion 111 which is a curved arm portion of the support base 110 is disposed so as to face the photoconductor 31, and the plate-shaped charged collection member 100 is bonded to the support portion 111 of the support base 110. It is fixed.
In this example, the support base 110 is made of, for example, a leaf spring material made of a conductive material, and is linearly connected to a housing (not shown) of a process cartridge via a stopper (not shown) such as a screw. It is fixed by fixing the attachment part 112 which is an arm part. The support base 110 is not limited to a leaf spring material, and may be appropriately selected from metal, resin, and the like.

In this example, the charge collection member 100 is a long plate-like member extending in the axial direction of the photoconductor 31 and has a curvature corresponding to the support portion 111 which is a curved arm portion of the support base 110. It has a recovery base material 101 made of a curved conductive member, and a covering layer 102 as a covering member that covers the opposing surface of the recovery base material 101 facing the photoreceptor 31.
Here, for example, a conductive rubber material is used as the recovery base material 101, but is not limited thereto, and other conductive materials can be used. For example, a conductive sponge, a conductive fiber, a conductive material can be used. Resin, conductive metal, etc. can be used. In this example, the recovery base material 101 is provided as a separate member from the support base material 110, but it goes without saying that the support base material 110 itself may also be used as the recovery base material 101.
Further, as shown in FIG. 8 (a), the covering layer 102 is made of a material having a charged column on the positive side of silica as the external additive W, and in particular, on the positive side in the charged column. Material is preferred. Furthermore, in this example, the coating layer 102 needs to be made of a material that is on the positive side of the charged column with respect to the surface material of the photoreceptor 31.
That is, if the charged column of silica as the external additive W is Cw, the charged column of the photosensitive member 31 is Cp, and the charged column of the coating layer 102 of the charged collection member 100 is Ck, the following relationship is satisfied.
+ ← Ck> Cw →-
+ ← Ck> Cp →-
For example, if the surface material of the photoreceptor 31 is polycarbonate, a material having a positive charge column on the covering layer 102 may be selected for the covering layer 102. In particular, Nylon (registered trademark), for example, is selected as a preferable material if a material on the positive side in the charging train is selected, and a material having excellent wear resistance and a low surface friction coefficient is selected. The Of course, any material other than nylon (registered trademark) can be used as long as it is on the plus side of the polycarbonate. In addition, when a material other than polycarbonate is used, such as when an overcoat layer is provided on the outermost surface of the photoconductor 31 or when an a-Si photoconductor is used, the charged column is more positive than the outermost material. Any material can be used.
Further, the coating layer 102 is preferably a thin layer, and in this embodiment, a coating layer having a thickness of 5 to 10 μm is used. As a method for forming the coating layer 102, for example, an electrostatic coating method can be used.

Furthermore, in the present embodiment, as shown in FIGS. 7 and 8A and 8B, the charged collection member 100 has a contact portion 105 in the vicinity of the center of the covering layer 102 in the moving direction of the photoreceptor 31. Is arranged in contact with the surface of the photoreceptor 31.
The contact portion 105 continuously extends linearly corresponding to the length of the recovery substrate 101 and is in contact with the photoconductor 31. In this example, the image forming area m and the axial direction of the photoconductor 31 A part of the non-image forming area located on both sides is also provided.
In particular, in this example, since the support portion 111 of the support base 110 is made of a leaf spring material and presses the charged collection member 100 toward the photoconductor 31, the charged collection member 100 is in contact with the contact portion 105. The state of contact with the surface of the body 31 is stably maintained. Further, since a conductive rubber material is used as the recovery base material 101, it is preferable to uniformly contact the photoconductor 31 and reduce the pressure of the contact portion 105 to suppress wear of the photoconductor 31 due to rubbing.
In this example, the charged member 100 has a gap 120 between the contact portion 105 and the surface of the photoconductor 31 in the upstream and downstream regions of the photoconductor 31 in the moving direction. .
The gap 120 has a wedge-shaped portion 121 that changes so that the distance between the charged member 100 and the photosensitive member 31 gradually increases as the distance from the contact portion 105 increases.
The gap dimension of the gap 120 is necessary for electrostatically collecting silica as the external additive W remaining on the photosensitive member 31 when the member to be charged 100 is frictionally charged by the photosensitive member 31. required to be selected, such as an electric field E ₁ is formed.
Therefore, it is preferable that the gap dimension of the gap portion 120 is narrow in that the electrostatic force acts on silica more strongly. Preferably, the upper limit is set to 1 mm or less, more preferably 0.5 mm or less.

<Refresh cycle>
Since silica recovered in the external additive temporary recovery device 37 accumulates, the recovery capability decreases. Therefore, in this example, the external additive W temporarily recovered in the external additive temporary recovery device 37 is used in the refresh cycle. This silica is removed from the external additive temporary recovery device 37.
Specifically, as shown in FIG. 7, an external additive discharge device 130 is added to the external additive temporary recovery device 37.
This external additive discharge device 130 is charged via a support substrate 110 with a discharge voltage Vt having a polarity (negative in this example) opposite to the polarity of the charge to which the coating layer 102 of the charged collection member 100 is frictionally charged. A discharge voltage power supply 131 to be applied to the recovery base material 101 of the recovery member 100 and a selection switch 132 that is connected in series to the discharge voltage power supply 131 and selects the application time of the discharge voltage Vt.
Here, the discharge voltage Vt, when applied to the charged collection member 100, the charged collection member by the action of the discharge electric field E ₂ is generated in the gap 120 between the photoconductor 31 and the charging recovery member 100 The silica as the external additive W temporarily collected in 100 may be appropriately selected as long as it is selected to such an extent that it can be discharged to the photoreceptor 31 side by electrostatic attraction.
The selection switch 132 is connected to, for example, the control device 140. The control device 140 rotates the photosensitive member 31 and the developing device 34 in a predetermined refresh cycle as shown in FIG. selection at the timing of passing through the developing roller 34b is rotated, for example, the non-image forming region R _N corresponding to inter-image area external additive temporary recovery position between the image forming region R _I to the moving direction of the photoconductor 31 switch 132 is turned on, and the discharge voltage Vt is applied to the charged collection member 100.
In particular, in this example, since the member to be charged 100 has the recovery base material 101 made of a conductive material, the discharge voltage Vt can be reliably applied to the coating layer 102, and the coating layer If 102 is a thin layer, it is effective in generating dielectric polarization in the whole coating layer 102 by the applied discharge voltage Vt.
Here, the refresh cycle may be performed at the start or end of the print job or for each predetermined number of prints separately from the normal image forming process, but in this example, the normal image forming process is performed. in parallel with, and to be carried out in consideration of the moving position of the non-image forming region R _N on the photoreceptor 31.

The external additive temporary recovery device 37 according to the present embodiment operates on the following operation principle.
<Temporary external additive recovery process>
First, when each image forming unit 30 performs an image forming operation, the photoreceptor 31 rotates at a predetermined process speed vp as shown in FIGS.
In this state, as shown in FIG. 9A, the contact portion 105 of the charged collection member 100 is frictionally charged to (+) by rubbing against the photoreceptor 31, and the coating layer 102 of the charged collection member 100 is charged. The whole is triboelectrically charged to (+). As a result, a charge (positive polarity) is generated in the coating layer 102 of the charged collection member 100 that is triboelectrically charged, and the gap 120 between the coating layer 102 of the charged collection member 100 and the photoreceptor 31 is generated by this charge. electric field E ₁ is generated on.
In particular, as shown by B ₁ or B ₂ in FIG. 9, a wedge-shaped portion 121 having a narrow interval is present in the vicinity of the contact portion 105 in the gap portion 120, and the electric field strength of the electric field E ₁ is high. ing.
On the other hand, the silica as the external additive W has a strong tendency to be negatively charged, and the silica as the external additive W that has passed through the cleaning blade 82 of the cleaning device 36 is charged to (−).

In this state, when the silica on the photoconductor 31 reaches the gap 120 of the member to be charged 100 as the photoconductor 31 rotates, the silica on the photoconductor 31 is statically caused by the electric field E ₁ in the gap 120. Move while receiving electro-suction force.
At this time, the wedge-shaped portion 121 shown in FIG. 9 in B _1, the silica on the photoconductor 31 for receiving the electrostatic attraction force field strength is intensified gradually as it moves, weak adhesion of silica on the photoreceptor 31 Silica is electrostatically attracted to and collected by the charged collection member 100.
The silica on the photoconductor 31 passes through the contact portion 105 indicated by A in FIG. 9. In this contact portion 105, the silica on the photoconductor 31 slides between the charged member 100 and the photoconductor 31. Because of the rubbing, it is presumed that the shear force F acts on the silica on the photoconductor 31 to reduce the silica adhesion, and the silica charge increases due to frictional charging. Therefore, silica that has passed through the contact portion 105 reaches the wedge portion 121 shown in FIG. 9 B ₂ located downstream side in the movement direction of the photoconductor 31, the charged collection member by the electrostatic attraction force by the electric field E ₁ It is electrostatically attracted to 100 and collected intensively. In this example, among the gaps 120, in particular, it is intensively collected in wedge-shaped portion 121 located downstream side in the movement direction of the photoconductor 31 that has passed through the contact portion 105 (in FIG. 9 B ₂ side).

Further, since a large amount of untransferred toner T remaining on the surface of the photoconductor 31 is present in the image forming area m of the photoconductor 31, silica as an external additive W that passes through the cleaning device 36 is also an image of the photoconductor 31. Although there are many in the formation region m, almost all of the silica on the photoconductor 31 is temporarily collected by the charged collection member 100 in the region of the gap 120 of the charged collection member 100 as described above.
For this reason, in the present embodiment, silica as the external additive W hardly reaches the portion charged by the charging device 32 to the photoconductor 31, so that the silica charged by the charging device 32 is used as the developing device 34. The development area is hardly reached, and as described above, there is no concern that a ghost image is generated during continuous printing. Further, for example, silica on the photoconductor 31 adheres to the discharge wires 321 and the grids 322 with the discharge action of the scorotron as the charging device 32, and there is no fear of causing a charging failure. For example, even if the charging device 32 uses a charging roll in contact with the photoreceptor 31, silica on the photoreceptor 31 hardly adheres to the charging roll, so silica adheres to the charging roll. There is no concern about charging failure.

<Refresh processing>
The external additive temporary collection device 37 is refreshed in a refresh cycle that is periodically performed.
In this example, as shown in FIGS. 7, 10, and 11 (a), the control device 140 controls the image forming area with respect to the timing at which the refresh cycle is determined in advance, specifically, the moving direction of the photoconductor 31. when non-image forming region R _N corresponding to inter-image area between the R _I is passed through the external additive temporary recovery position corresponding to the installation position of the external additive temporary recovery device 37, thereby turned on the selection switch 132.
At this time, the discharge voltage Vt (negative polarity in this example) is applied to the charge collection member 100 via the support base 110 from the discharge voltage power supply 131 to the charge collection member 100.
Then, in the charged member 100, the discharge voltage Vt is applied to the entire coating layer 102 through the recovery base material 101 made of a conductive material, dielectric polarization occurs in the coating layer 102, and the surface potential of the coating layer 102 becomes the discharge voltage Vt. become. Therefore, it acts discharge electric field E ₂ based on the discharge voltage Vt in the gap 120 between the photosensitive member 31 and the charging recovery member 100.

The discharge electric field E ₂ is an electric field having a polarity opposite to that of the electric field E ₁ based on the electric charge during the temporary collection of the external additive, and the silica as the external additive W that has been temporarily collected in the charged collection member 100 is negative. It is charged and is discharged to the photoconductor 31 side by the electrostatic attraction force by the discharge electric field E _2. Particularly, in the wedge-shaped portion 121 (see B ₁ and B _{2 in} FIG. 10) located in the vicinity of the contact portion 105 (see A in FIG. 10) in the gap 120, the electric field strength of the discharge electric field E ₂ is strong. The silica temporarily recovered by the charged member 100 corresponding to the wedge-shaped portion 121 is reliably discharged to the photoreceptor 31 side.
As a result, the silica as the external additive W is electrostatically attached to the photoconductor 31 by the Coulomb force, and passes through the external additive temporary recovery device 37 as the photoconductor 31 moves. At this time, silica that has been temporarily recovered in the moving direction of the photosensitive member 31 relative to the contact portion 105 in the electrified collection member 100 is ejected to the photosensitive member 31 and then passes through the contact portion 105. , by the Coulomb effect electrostatic adhesion force and by the discharge electric field E ₂ by the image force from being held on the photosensitive member 31, passing through the contact portion 105 without adhering to the contact portion 105 of the charging recovery member 100 .
Then, the silica as the external additive W reattached to the surface of the photoreceptor 31 passes through the charging device 32 and reaches the developing area of the developing device 34 as shown in FIGS. 7 and 11B. However, in the developing area of the developing device 34, the developer G held on the developing roll 34b rubs the surface of the photosensitive member 31, so the photosensitive member is rubbed by the sliding force (scavenging force) of the developer G. Silica on 31 is collected in the developing container 34 a of the developing device 34.
As a result, the silica as the external additive W temporarily recovered in the external additive temporary recovery device 37 is recovered again in the developing device 34 and reused.

Embodiment 2
FIG. 12 is an explanatory diagram showing a main part of the image forming apparatus according to the second embodiment.
In the figure, the basic configuration of the image forming apparatus is substantially the same as that of the first embodiment, but includes an external additive temporary recovery device 37 different from that of the first embodiment. Components similar to those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof is omitted here.
In FIG. 13, the external additive temporary recovery device 37 has a configuration in which the charged recovery member 100 is supported on the support base 110, as in the first embodiment, as shown in FIG. A support base 110 and a charged collection member 100 different from those in Embodiment 1 are used.
In the present embodiment, the support base 110 is made of a conductive member having a substantially L-shaped cross section extending along the axial direction of the photoconductor 31, and the support portion 113, which is one arm portion, faces the photoconductor 31. The plate-like charged recovery member 100 is bonded and fixed to the support portion 113 of the support base 110, and a stopper (not shown) such as a screw is attached to the housing (not shown) of the process cartridge. It is fixed by fixing the attachment part 114 which is the other arm part via.
In this example, the support base 110 is made of, for example, a leaf spring material made of a conductive material, but is not limited thereto, and may be appropriately selected from metal, resin, and the like.
Further, the charged member 100 covers the periphery of the recovery substrate 151 other than the plate-like recovery substrate 151 whose one side is bonded and fixed to the support substrate 110 and the surface of the recovery substrate 151 fixed to the support substrate 110. And a covering layer 152 as a covering member.

In this example, the recovery base material 151 has a plate-like member having a substantially rectangular cross section made of, for example, a conductive rubber material, and faces the moving direction of the photoconductor 31 at a portion of the plate-like member facing the photoconductor 31. Thus, a plurality of (for example, five in this example) convex portions 161 to 165 whose height changes are integrally formed.
The plurality of convex portions 161 to 165 are formed in a triangular or quadrangular cross section. In this example, the convex portions 161 to 164 are formed in a triangular shape having a protruding end corner on the upstream side in the moving direction of the photoconductor 31, and the convex portion 165 has a protruding end corner on the upstream side in the moving direction of the photoconductor 31. It is formed in a quadrangular cross section whose height is lower than the protruding end corner on the downstream side.
Each position (P _{1 to} P _{5 in the} figure) of the protruding end corners of the convex portions 161 to 164 and the protruding end corner portion of the convex portion 165 located on the downstream side in the moving direction of the photoconductor 31 is a drum-shaped photoconductor. It is arranged at a position along the curvature of the surface of 31.
The surface of the recovery base material 151 having such a shape other than the fixed surface is covered with the above-described coating layer 152, and the convex portions 161 to 165 of the recovery base material 151 are also covered with the coating layer 152. The material of the covering layer 152 is substantially the same as that of the first embodiment, and a material in which the charge train is positioned on the plus side compared to the silica as the external additive W and the photoreceptor 31 is selected. .

The to-be-charged recovery member 100 having such a configuration is supported by the support base 110 and pressed against the surface of the photoconductor 31 by a predetermined constant pressure by the elastic action of the leaf spring material of the support base 110.
In this state, in the charged member 100, the portion corresponding to the protruding end corner along the curvature of the surface of the photoreceptor 31 of each of the convex portions 161 to 165 is disposed in contact with the surface of the photoreceptor 31 as the contact portion 170. ing.
Further, in this example, the portions adjacent to the contact portions 170 of the respective convex portions 161 to 165 of the charged collection member 100 are located between the respective convex portions 161 to 165 of the charged collection member 100 and the surface of the photoreceptor 31. A plurality of gaps 180 are formed.
In this example, each gap portion 180 is provided on the downstream side of each of the convex portions 161 to 165 in the movement direction of the photosensitive member 31, and the interval between the charged collection member 100 and the photosensitive member 31 is separated from the contact portion 170. It has the wedge-shaped part 181 which changes so that it may become large gradually.
Further, in this example, the external additive temporary recovery device 37 is added with an external additive discharge device 130 (discharge voltage power supply 131, selection switch 132) similar to that of the first embodiment, and refreshed by the control device 140. A cycle is to be implemented.

Next, the operation of the external additive temporary recovery device 37 in the present embodiment will be described.
Now, when each image forming unit 30 performs an image forming operation, the photoreceptor 31 rotates at a predetermined process speed vp, as shown in FIG.
In this state, the contact portions 170 corresponding to the convex portions 161 to 165 of the charged collection member 100 are frictionally charged to (+) by rubbing against the photosensitive member 31, and the coating layer 152 of the charged collection member 100 is charged. The whole is triboelectrically charged to (+). As a result, a charge (positive polarity) is generated in the coating layer 152 of the charged collection member 100 that is frictionally charged, and a plurality of gaps between the coating layer 152 of the charged collection member 100 and the photoconductor 31 are generated by this charge. An electric field E ₁ is generated in the part 180.
In particular, the plurality of gap portions 180 are all secured on the downstream side of the contact portion 170 in the moving direction of the photosensitive member 31 and have wedge-shaped portions 181 with a narrow interval, and the electric field intensity of the electric field E ₁ is high. It has become.
On the other hand, the silica as the external additive W has a strong tendency to be negatively charged, and the silica as the external additive W that has passed through the cleaning blade 82 of the cleaning device 36 is charged to (−).

In this state, when the silica on the photoconductor 31 passes through the first contact portion 170 (P _{1 in} FIG. 14) of the convex portion 161 of the charged collection member 100 as the photoconductor 31 rotates, the contact portion. In 170, since the silica on the photoconductor 31 is rubbed between the charged member 100 and the photoconductor 31, a force in the shear direction acts on the silica on the photoconductor 31 and the silica adhesion force is increased. It is presumed that the charge of silica increases due to reduction and frictional charging. Therefore, silica that has passed through the first contact portion 170 reaches the first wedge-shaped portion 181 of the gap 180 illustrated in FIG. 14 in B ₁ located in the moving direction downstream side of the photosensitive member 31, the electric field E ₁ It is electrostatically attracted to the charged collection member 100 by the electrostatic attraction force by and collected in a concentrated manner.
At this time, the silica on the photoconductor 31 that has not been temporarily collected by the charged member 100 when passing through the first gap portion 180 becomes the second and subsequent contact portions 170 (P _{2 to} P _{5 in} FIG. 14). ) And the second and subsequent gaps 180 alternately. In this state, silica on the photoreceptor 31, the silica was low charged since frictional charging each passing through the second and subsequent contact portion 170 is also assumed to be steadily charged, the electrostatic attraction due to the electric field E ₁ force by, when passing through the downstream side of the gap 180 illustrated in FIG. 14 _{B 2} (fourth gap section 180 in FIG. 14), it is collected in the charged collection member 100.
In the case where silica is intensively and temporarily collected on the member to be charged 100 at a portion corresponding to the gap portion 180 located on the upstream side in the moving direction of the photoreceptor 31 among the plurality of gap portions 180, the gap Although the silica recovery performance in the portion 180 is reduced, the silica is temporarily recovered in the gap portion 180 located on the downstream side. Therefore, in the aspect having the plurality of contact portions 170 and the plurality of gap portions 180, the external additive W It is possible to separate and maintain the recovery performance of silica as a relatively long time.
Also in the present embodiment, when the refresh cycle similar to that of the first embodiment is performed and the external additive discharge device 130 operates on the external additive temporary recovery device 37, the temporary recovery is performed on the charged recovery member 100. silica as an external additive W is discharged in the non-image forming region R _N of the photosensitive member 31 side, brought to the developing zone of the developing device 34 with the movement of the photosensitive member 31, held to the developing roller 34b the developer G And is collected again in the developing container 34a.

Example 1
The image forming apparatus according to Embodiment 1 was used as Example 1, and an experiment for verifying the effect of the external additive temporary recovery device 37 was performed. A mode in which the external additive temporary recovery device 37 is not provided is referred to as Comparative Example 1.
The experimental conditions are as follows.
In the verification experiment, an on-demand printer DocuColor 8000 manufactured by Fuji Xerox was used, and an external additive temporary recovery device 37 was incorporated between the cleaning device 36 and the charging device 32.
-Toner used: Toner having an average particle diameter of 5.8 μm produced by an emulsion polymerization method (silica having a number average particle diameter of 100 to 150 nm is externally added)
Cleaning blade: Urethane rubber blade with a pressure of 39.2 N / m Seal member: Thermoplastic polyurethane film with a thickness of 0.1 mm
A conductive rubber having a length of 20 mm and a thickness of 2 mm was used as the recovery substrate 101.
A nylon coating having a thickness of 5 to 10 μm was used as the covering layer 102.
In the evaluation method, a ghost evaluation chart (for example, see FIG. 3A) was continuously printed 50 sheets, and the ghost level of the 50th sheet was evaluated by ΔL *. Here, ΔL * means, for example, the brightness difference between the area where the ghost image IMg exists in FIG. 3B and the area of the halftone image IM ₂ other than this area.
The evaluation results are shown in FIG.
According to the figure, the smaller the value of ΔL *, the better the ghost level.
In Comparative Example 1, the value of ΔL * was 2.0 and the occurrence of continuous print ghost was observed, whereas in Example 1, the value of ΔL * was reduced to 0.1 and the continuous print ghost was recognized. It is understood that it will improve to a level that is not done.
Moreover, regarding the improvement effect of the external additive temporary recovery device 37 in Example 1, a running test was performed in order to confirm its maintainability.
The total number of running cycles (total number of rotations of the photoreceptor) is 100,000 cycles. As a result of ghost evaluation performed every 10,000 cycles in the same manner as described above, the value of ΔL * changes from 0.1 to 0.2 as shown in FIG. 16, and it is determined that there is no change taking measurement variation into consideration. The sustainability of Example 1 was confirmed.

Example 2
When the image forming apparatus having the same configuration as that of the first embodiment is set to the second embodiment and the refresh cycle is performed with the discharge voltage Vt being −400 V, the surface of the charged collection member 100 of the external additive temporary collection device 37 after the refresh cycle is obtained. As a result of examining the degree of silica adhesion, it was confirmed that the silica temporarily collected on the charged collection member 100 was substantially removed and the charged collection member 100 was refreshed.
The image forming apparatus according to the second embodiment is defined as Example 3, and similarly to Example 1, a verification experiment was conducted using DocuColor 8000 with a total cycle number of 100,000 cycles.
As a result, the value of ΔL * was changed from 0.1 to 0.15, and it was confirmed that continuous print ghosts could be prevented from occurring for a long time.

DESCRIPTION OF SYMBOLS 1 ... Image holding body, 2 ... Latent image formation means, 2a ... Charging means, 2b ... Latent image writing means, 3 ... Development means, 3a ... Developing container, 3b ... Developer holding body, 3c ... Development rotating body, 3d DESCRIPTION OF SYMBOLS ... Magnet member, 3e ... Agitation conveyance member, 4 ... Transfer means, 5 ... Transfer medium, 6 ... Cleaning means, 6a ... Cleaning member, 10 ... External additive temporary collection means, 11 ... Charged collection member, 11a ... Collection base wood, 11b ... cover member, 12 ... contact portion, 13 ... gap, 15 ... external additive discharge means, 16 ... external additive recollection unit, E 1 _... electric field based on the electric charges generated by triboelectric charging, _{E 2} ... Ejecting electric field, G ... Developer, W ... External additive

Claims (9)

A rotatable image carrier that holds the electrostatic latent image;
A latent image forming means for forming an electrostatic latent image based on an image signal on the image carrier;
A developer holder that holds and conveys the toner, the carrier, and a developer containing an external additive having the same polarity as the toner; and the developer held and conveyed by the developer holder is slid against the image carrier. Developing means for developing the electrostatic latent image formed on the image carrier by the latent image forming means;
Transfer means for transferring the toner image on the image carrier developed by the developing means to a transfer medium;
A cleaning unit that is provided on the downstream side in the rotation direction of the image carrier from the transfer site by the transfer unit, and that cleans the post-transfer residue on the image carrier with a cleaning member that contacts the image carrier;
An external additive temporary recovery means that is provided on the downstream side in the rotation direction of the image holding member with respect to the cleaning portion by the cleaning means and temporarily recovers the external additive on the image holding member that has passed through the cleaning portion; Prepared,
The external additive temporary recovery means includes:
It is arranged so as to face the image carrier and extend in a direction intersecting with the rotation direction of the image carrier, and at least the opposite part facing the image carrier has a charged column more than the external additive and the image carrier. A charged collection member made of a material located on the plus side;
Contact that is provided on a part of the charged member to be in contact with the surface of the image carrier and frictionally charges the charged member due to contact with the image carrier when the image carrier rotates. And
The charge collection member is provided between a portion facing the image carrier excluding the contact portion and the image carrier, and an interval between the opposite portion of the charge collection member and the image carrier is A portion that gradually increases as the distance from the contact portion increases, and when the member to be charged is frictionally charged by the contact portion, an electric field based on the charge generated by the frictional charging is externally applied on the image carrier. A gap that allows the additive to act to an electrostatic capacity; and
An image forming apparatus comprising: The image forming apparatus according to claim 1.
The gap portion has a portion that gradually increases as the distance between the opposed portion of the charge collection member and the image carrier increases from the contact portion, at least on the downstream side of the contact portion in the moving direction of the image carrier. An image forming apparatus. The image forming apparatus according to claim 1, wherein
The contact portion of the external additive temporary recovery means extends linearly in a direction crossing the moving direction of the image carrier, and continuously contacts at least within the image forming area of the surface of the image carrier. An image forming apparatus. The image forming apparatus according to claim 1,
Further, a discharge voltage having a polarity different from the triboelectric charge polarity of the charged collection member is applied to the charged collection member, and a discharge electric field based on the discharge voltage is applied between the charged collection member and the image carrier. An external additive ejecting means for ejecting the external additive temporarily collected on the charged collection member to the image carrier side;
The image holding body on which the external additive discharged by the external additive discharging means is reattached is rotated, and the developer holding body is rotated in the developing area of the developing means to slide on the image holding body. An external additive recollecting means for returning the external additive reattached by the rubbing developer to the developing means;
An image forming apparatus comprising: The image forming apparatus according to claim 4.
The external additive discharging means discharges the temporarily collected external additive to a non-image forming area interposed between image forming areas in the moving direction of the image carrier. The image forming apparatus according to claim 4 or 5,
The charged recovery member of the external additive temporary recovery means is provided so as to cover a surface of the recovery base made of a conductive member and the surface of the recovery base facing the image carrier, and the external additive and image A covering member made of a material in which the charged column is positioned on the plus side of the holding body,
The image forming apparatus according to claim 1, wherein the external additive discharge means applies a discharge voltage to the recovery substrate. The image forming apparatus according to claim 1,
The charge collection member is disposed at a predetermined position via a support member, and the support member is formed of an elastic member that elastically presses the charge collection member toward the image carrier. An image forming apparatus. The image forming apparatus according to claim 1,
The external additive temporary recovery means includes:
The charged member having a planar or curved opposing surface, which is configured by a plate-like member extending in a direction intersecting the moving direction of the image carrier, and a portion of the plate-like member facing the image carrier is planar or curved. ,
The contact portion for bringing the opposing surface of the plate-shaped member away from the upstream and downstream ends in the moving direction of the image carrier into contact with the surface of the image carrier;
The gap formed on the upstream side and the downstream side in the moving direction of the image carrier with the contact part as a boundary;
An image forming apparatus comprising: The image forming apparatus according to claim 1,
The external additive temporary recovery means includes:
The plate-shaped member extends in a direction crossing the moving direction of the image holding body, and the height of the plate-like member changes in the moving direction of the image holding body at a portion facing the image holding body. The charged collection member having a plurality of convex portions;
The contact portion for bringing the protruding ends of a plurality of convex portions formed on the plate-like member into contact with the surface of the image carrier;
The gap portion provided adjacent to the contact portion and formed in a plurality between the plurality of convex portions and the image holding body,
An image forming apparatus comprising:

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