JP2009300924A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration of the image quality due to inversely charged developer from being supplied to an image carrier. <P>SOLUTION: A developing device 34 comprises: a developing roller 341 which is composed of a roller member 341a having a first pole 341c disposed on a position opposite to a photoreceptor drum 31 and a second pole 341d disposed side by side with the first pole 341c in the circumferential direction, having a magnetic pole reverse to the magnetic pole of the first pole 341c and a sleeve 341b for covering the roller member 341a and conveying the developer to a position opposite to the photoreceptor drum 31; a developing container 342 capable of storing the developer therein; and a regulation member 345 for regulating the thickness of a layer of the developer to be conveyed to a position of the sleeve 341b corresponding to the second pole 341d. A collection member 351 is arranged so as to face the second pole 341d and collects inversely charged material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus capable of forming an image using a two-component developer.

  An image forming apparatus capable of forming an image using a two-component developer has an image forming unit capable of forming an image based on image information. The image forming unit includes an image carrier capable of carrying an electrostatic latent image on the surface, and a developing device capable of supplying a developer to the image carrier. The developing device is disposed so as to face the image bearing member, and includes a developing roller having a roller member having a plurality of magnetic poles and a sleeve covering the roller member, and a thickness of a developer layer adhered to the surface of the developing roller. And a developing container that supports the regulating member and can store the developer therein.

  In this image forming apparatus, the developer stored in the developing container is attracted to the magnetic pole and attached to the sleeve surface. Then, the sleeve is rotated with the developer attached to the surface. At this time, the thickness of the developer layer adhered to the surface of the sleeve is regulated by the regulating member. Thereafter, the sleeve further rotates, the developer is conveyed to the vicinity of the image carrier, and toner is supplied to the electrostatic latent image carried on the image carrier. In this way, an image by the developer is formed on the image carrier (see Patent Document 1).

JP-A-5-241437

  In an apparatus for forming an image using a two-component developer such as the image forming apparatus described in Patent Document 1, the toner is charged by the friction between the carrier and the toner when the image forming operation is performed. When the toner is charged, the external additive attached to the toner may be peeled off. In addition, wear of the carrier may occur. As described above, when the external additive is peeled off from the toner or the carrier is depleted, the toner is charged by the toner from which the external additive has been peeled off or the carrier that has been depleted. In this case, the toner may be charged to a polarity opposite to the normal charging polarity. When the toner is reversely charged in this way, the reversely charged toner is supplied to a position other than the position where the electrostatic latent image on the image carrier is carried, and fogging or the like occurs. For this reason, the image quality is degraded.

  An object of the present invention is to prevent deterioration in image quality caused by supplying a reversely charged developer to an image carrier.

  An image forming apparatus according to a first aspect is an image forming apparatus that forms an image using a two-component developer, and includes an image carrier, a developing device, and a collecting member. The developing device includes a roller member having a first pole provided at a position facing the image carrier, and a second pole that is arranged side by side with the first pole in the circumferential direction and is opposite to the first pole. A developing roller having a sleeve for covering the roller member and conveying the developer to a position facing the image carrier, a developing container capable of storing the developer therein, and a sleeve corresponding to the second pole And a regulating member that regulates the thickness of the developer layer conveyed to the position. The collecting member is disposed so as to face the second pole, and collects reversely charged objects that are reversely charged.

  In this image forming apparatus, the developer stored inside the developing container adheres to the sleeve. Then, the developer is conveyed along with the rotation of the sleeve. At this time, the thickness of the developer layer attached to the sleeve is regulated by the regulating member. Then, the charged material reversely charged by the collecting member is collected. Thereafter, the developer is supplied to the image carrier from the first pole side.

  Here, after the thickness of the developer layer adhering to the sleeve is regulated by the regulating member and before the toner is supplied to the image carrier, the reversely charged reversely charged material is collected by the collecting member. can do. For this reason, it is difficult for the reversely charged developer to be supplied to the image carrier, and it is possible to prevent the image quality from being deteriorated.

An image forming apparatus according to a second aspect is the image forming apparatus according to the first aspect, wherein the second pole is disposed adjacent to the first pole.
Here, in a state where the developer is located at a position corresponding to the second pole of the sleeve, the charged material that is normally charged is moved to a position far from the sleeve by the collecting member. For this reason, when the developer is transported from the position corresponding to the second pole of the sleeve to the position corresponding to the first pole, the normally charged charged substance remaining on the sleeve moves to the vicinity of the sleeve surface. Therefore, it is possible to make it difficult to supply a reversely charged object that is reversely charged to the image carrier. For this reason, it is possible to prevent deterioration in image quality.

  An image forming apparatus according to a third aspect is the image forming apparatus according to the first or second aspect, wherein the roller member is disposed adjacent to the second pole, and is the same as the first pole at a position facing the regulating member. It has a third pole of the magnetic pole.

  Here, the magnetic brush is formed at a position corresponding to the sleeve of the third pole, and the height of the magnetic brush (the thickness of the developer layer) is restricted by the restriction member. Therefore, the distance between the image carrier and the tip of the magnetic brush can be kept constant, and the toner can be stably supplied to the image carrier. Here, the magnetic brush means a state in which the carrier and the toner contained in the two-component developer are continuously arranged like a chain, and is sometimes called a developer ear.

  An image forming apparatus according to a fourth aspect is the image forming apparatus according to any one of the first to third aspects, wherein the collecting member has a conductive film member. The collecting member further includes a voltage applying device capable of applying a voltage to the conductive film member. The voltage application device applies a voltage to the conductive film member so that the conductive film member attracts the reversely charged material during the image forming operation.

  Here, the oppositely charged substance is electrically attracted to the collecting member.

  An image forming apparatus according to a fifth aspect is the image forming apparatus according to the fourth aspect, wherein the voltage applying device applies a voltage to the conductive film member so that the charged substance separates from the conductive film member during the non-image forming operation. Apply.

  Here, it is possible to prevent the reversely charged substance from accumulating on the collecting member.

  An image forming apparatus according to a sixth aspect is the image forming apparatus according to the fifth aspect, wherein the sleeve is a member capable of forming a magnetic brush on the surface. The conductive film member is disposed at a position where it can contact the tip of a magnetic brush formed on the surface of the sleeve.

  Here, since the conductive film member is disposed at a position where the tip of the magnetic brush can come into contact, the charged matter attached to the conductive film member can be removed by the magnetic brush as the sleeve rotates. Moreover, it becomes easy to adhere the charged substance adhering to the tip of the magnetic brush to the conductive film member. Here, since the charged material is collected at the tip of the magnetic brush by the second pole, the charged material can be collected efficiently.

  An image forming apparatus according to a seventh aspect of the present invention is the image forming apparatus according to the fifth or sixth aspect, further comprising a removal mechanism capable of removing charged substances on the conductive film member.

  Here, it is possible to prevent the charged material from accumulating on the conductive film member.

  An image forming apparatus according to an eighth aspect of the present invention is the image forming apparatus according to the seventh aspect, wherein the removing mechanism has a discharge duct capable of discharging the charged substance out of the developing device.

  An image forming apparatus according to a ninth aspect is the image forming apparatus according to the third aspect, wherein the roller member is disposed adjacent to the third pole, and the developer stored in the developing container is adsorbed to the surface of the sleeve. And a fourth pole for making them.

  Here, the developer in the developing container is easily attached to the sleeve.

  An image forming apparatus according to a tenth aspect is the image forming apparatus according to the third or ninth aspect, wherein the roller member is disposed so as to be adjacent to the first pole, and further has a fifth pole having the same magnetic pole as the second pole. Have.

  An image forming apparatus according to an eleventh aspect is the image forming apparatus according to the third aspect, wherein the roller member has only the second pole between the first pole and the third pole.

  In the present invention, it is possible to prevent the image quality from being deteriorated due to the reversely charged developer being supplied to the image carrier.

[overall structure]
An MFP 1 as an image forming apparatus according to the present invention will be described below with reference to FIG. Here, FIG. 1 shows an overall outline of the multifunction machine 1 according to the present invention. The multifunction device 1 is connected to an external computer or the like, and can form an image on a sheet using a two-component developer based on image information read from a document or image information sent from a computer.

  The multifunction device 1 has various functions such as a function of copying a document and a function of transmitting image information of the document. As shown in FIG. 1, the multifunction device 1 includes a document reading unit 2, an image forming unit 3, a transfer unit 4, a sheet storage unit 5, a sheet transport unit 6, a fixing unit 7, and a discharge unit 8. It has. The configuration of each functional unit will be described below.

{Original reading section}
The document reading unit 2 is a part for reading image information of a document. The document reading unit 2 is disposed at the top of the multifunction device 1.

{Image forming part}
The image forming unit 3 is a part for forming an image on a sheet based on image information. The image forming unit 3 is disposed between the paper storage unit 5 and the document reading unit 2. Further, the image forming unit 3 includes a photosensitive drum 31, a charging device 32, a laser unit 33, a developing device 34, a collection / removal mechanism 35 (see FIG. 2), and a drum cleaning device 36. The developing device 34 and the collection / removal mechanism 35 will be described in detail later.

  The photosensitive drum 31 is a member capable of carrying an electrostatic latent image on the surface. Further, the photosensitive drum 31 is rotatable around a rotation axis extending perpendicularly to the paper surface of FIG. Further, the photosensitive drum 31 is a member that rotates in the direction of arrow A in FIG.

  The charging device 32 is a device for uniformly charging the surface of the photosensitive drum 31. The charging device 32 is disposed on the upper side of the photosensitive drum 31. Specifically, the charging device 32 uniformly charges the surface of the photosensitive drum 31 positively.

  The laser unit 33 is a device for irradiating the surface of the photosensitive drum 31 with laser light based on image information. The laser unit 33 is disposed on the upper side of the photosensitive drum 31.

  The drum cleaning device 36 is a device for cleaning developer remaining on the photosensitive drum 31 without being used for the developing operation.

{Transcription part}
The transfer unit 4 is a part for transferring the image formed by the image forming unit 3 to a sheet. The transfer unit 4 includes a transfer roller 41. The transfer roller 41 is disposed so as to face the photosensitive drum 31. The transfer roller 41 is a roller having a smaller diameter than the photosensitive drum 31. The transfer roller 41 has a rotation shaft provided in parallel with the rotation shaft of the photosensitive drum 31. A voltage applying device (not shown) is connected to the transfer roller 41. A voltage is applied to the transfer roller 41 from a voltage application device (not shown).

{Paper storage}
The paper storage unit 5 is a part for storing paper. The paper storage unit 5 is disposed at the lower part of the multifunction machine 1. Further, the paper storage unit 5 has a plurality of paper feed cassettes 51. Each paper cassette 51 stores different types (sizes, etc.) of paper. A plurality of paper feed cassettes 51 are stacked.

{Paper transport section}
The paper transport unit 6 is a part for transporting paper to each functional unit. The paper transport unit 6 has a paper transport path for transporting paper in the order of the paper storage unit 5, the image forming unit 4, the fixing unit 7, and the discharge unit 8.

{Fixing part}
The fixing unit 7 is a part for fixing an image on a sheet. The fixing unit 7 is disposed between the transfer unit 4 and the discharge unit 8. The fixing unit 7 includes a heating roller 71 for heating the paper image and a pressure roller 72 for pressing the paper image.

{Discharge unit}
The discharge unit 8 is a part for discharging the sheet to the outside of the multifunction device 1. As shown in FIG. 1, the discharge unit 8 is disposed downstream of the fixing unit 7 in the sheet conveyance direction. The discharge unit 8 has a discharge roller 81.
[Developer]
The developing device 34 is a device for supplying toner to the photosensitive drum 31. Further, the developing device 34 is disposed in the vicinity of the photosensitive drum 31. As illustrated in FIG. 2, the developing device 34 includes a developing roller 341, a developing container 342, a first stirring screw 343, a second stirring screw 344, and a regulating member 345. Here, FIG. 2 is a diagram showing the configuration of the developing device 34 and the configuration of the collection and removal mechanism 35.

  The developing roller 341 is a member for supplying toner to the photosensitive drum 31. The developing roller 341 is disposed so as to face the photosensitive drum 31. The developing roller 341 is a roller having a smaller diameter than the photosensitive drum 31. The developing roller 341 includes a roller member 341a and a sleeve 341b.

  The roller member 341a has a first pole 341c, a second pole 341d, a third pole 341e, a fourth pole 341f, and a fifth pole 341g.

  The first pole 341 c is a magnetic pole for forming a magnetic brush at a position facing the photosensitive drum 31. The first pole 341 c is disposed at a position facing the photosensitive drum 31. The first pole 341c is an N pole.

The second pole 341d is a magnetic pole for forming developer on the sleeve 341b at a position corresponding to the first pole 341c of the sleeve 341b. The second pole 341d is arranged side by side with the first pole 341c in the circumferential direction. The second pole 341d is adjacent to the first pole 341c. The second pole 341d is disposed at a position facing the collecting member 351. The second pole 341d is an S pole opposite to the magnetic pole of the first pole 341c.
The third pole 341e is disposed such that the second pole 341d is disposed between the third pole 341e and the first pole 341c. That is, the third pole 341e is disposed at a position adjacent to the second pole 341d and facing the regulating member 345. The third pole 341e is an N pole like the first pole 341c.

  The fourth pole 341f is adjacent to the third pole 341e. The fourth pole 341f is disposed in the vicinity of the first stirring screw 343. The fourth pole 341f is a magnetic pole for attaching the developer stored in the developing container 342 to the surface of the sleeve 341b. The fourth pole 341f is the S pole.

  The fifth pole 341g is a magnetic pole for separating the developer from the sleeve 341b with the fourth pole 341f. That is, since the fifth pole 341g has the same magnetic pole as the fourth pole 341f, a repulsive force is generated between the fourth pole 341f and the fifth pole 341g. The developer attached to the sleeve 341b is separated from the sleeve 341b by the repulsive force. The fifth pole 341g is a magnetic pole for preventing the developer from spilling from the inside of the developing container 342 to the outside. That is, the developer in the developing container 342 is prevented from spilling outside due to the magnetic field of the fifth pole 341g. The fifth pole 341g is disposed between the fourth pole 341f and the first pole 341c. The fifth pole 341g is the S pole.

  The sleeve 341 b is a member for transporting the developer to a position facing the photosensitive drum 31. The sleeve 341b is a member arranged so as to cover the surface of the roller member 341a. The sleeve 341b is a cylindrical member. The sleeve 341 b is a member that can rotate around a rotation axis parallel to the rotation axis of the photosensitive drum 31. The sleeve 341b is a member that can carry a developer on its surface. The sleeve 341b is a member that rotates in the direction of arrow B in FIG.

  The developing container 342 is a member that can store a two-component developer therein. As shown in FIG. 3, the two-component developer mainly includes a toner 91 and a carrier 92. The developing container 342 has an opening on the photosensitive drum 31 side. A developing roller 341 is supported in this opening. Further, the developing container 342 has a partition plate 342a inside. The partition plate 342a is disposed so as to extend in a direction orthogonal to the paper surface of FIG.

  The first stirring screw 343 is a member for stirring the developer in the developing container 342. Further, the first stirring screw 343 is disposed inside the developing container 342. The first stirring screw 343 is disposed in the vicinity of the developing roller 341. The first stirring screw 343 is arranged in parallel with the developing roller 341. The first stirring screw 343 rotates in the direction of arrow C in FIG.

  The second stirring screw 344 is a member for stirring the developer in the developing container 342. Further, the second stirring screw 344 is arranged side by side with the first stirring screw 343. And the 2nd stirring screw 344 is a member which can rotate in the arrow D direction of FIG.

  The regulating member 345 is a member for regulating the amount of developer attached to the sleeve 341b. That is, it is a member for regulating the height of the magnetic brush on the sleeve 341b. Further, the regulating member 345 is a plate-like member. The regulating member 345 extends in a direction perpendicular to the paper surface of FIG. The regulating member 345 is supported by the developing container 342. The end of the regulating member 345 facing the developing roller 341 is located in the vicinity of the developing roller 341.

[Collecting and removing mechanism]
The collection / removal mechanism 35 is a mechanism for collecting and removing positively charged toner, paper dust, and the like. The collection / removal mechanism 35 includes a collection member 351, a voltage application device 352, and a suction duct 353, as shown in FIG.

  The collecting member 351 has a conductive film-like member. Further, the collecting member 351 is arranged so as to extend in a direction perpendicular to the paper surface of FIG. Further, the collecting member 351 is disposed at a position facing the second pole 341d. In other words, it is disposed between the regulating member 345 and the photosensitive drum 31 in the circumferential direction. In other words, it is disposed below the photosensitive drum 31 and in the vicinity of the developing roller 341. The collecting member 351 has the same curvature as that of the sleeve 341b. For this reason, the distance between the collection member 351 and the sleeve 341b is constant in the circumferential direction. And the collection member 351 is arrange | positioned in the position which the front-end | tip of the magnetic brush formed on the sleeve 341b can contact as shown in FIG.

The voltage applying device 352 is a member that can apply a voltage to the collecting member 351. The voltage application device 352 is connected to the collecting member 351. The voltage application device 352 includes a positive power source 352a, a negative power source 352b, and a switch 352c that switches the power source connected to the collection member 351. Here, in the voltage application device 352, the collecting member 351 is connected to the minus power source 352b during the collection of positively charged toner or paper dust, that is, during the image forming operation, and the collecting member 351 is connected to the plus power source 352a during the removing operation. The switch 352c is switched so as to be connected.
The suction duct 353 is a part for sucking the collected toner and discharging it to the outside of the apparatus. The suction duct 353 is provided in the vicinity of the developing device 34. The suction duct 353 has a suction passage 353b formed between the outer surface of the developing container 342 and a plate-like member 353a disposed at a predetermined interval from the outer surface of the developing container 342. The suction duct 353 has a suction filter 353c disposed in the suction passage 353b. The suction filter 353c is a member to which toner can adhere. A suction device (fan) (not shown) is disposed at one end of the suction duct 353. The toner on the other end side of the suction duct 353 is sucked into the suction duct 353 by a suction device (not shown). The toner sucked into the suction duct 353 by a suction device (not shown) is attached to the suction filter 353c.
The collection member 351, the positive power source 352a, and the suction duct 353 constitute a removal mechanism. In this removing mechanism, a positive voltage is applied to the collecting member 351 from the positive power source 352a, and the magnetic brush sweeps out the toner collected on the collecting member 351 as the sleeve 341b rotates. Then, the toner swept out by the suction duct 353 is sucked. By this operation, the positively charged toner collected on the collecting member 351 is removed.

[Operation]
Next, the operation of the multifunction device 1 will be described.

  When image information of an original is read by the original reading unit 2 or image information is sent from a computer connected to the outside of the multifunction machine 1, an electrostatic latent image is formed on the photosensitive drum 31 based on the image information. . Specifically, the surface of the photosensitive drum 31 is charged by the charging device 32, and laser light is irradiated from the laser unit 33 to the photosensitive drum 31 based on the image information. When the electrostatic latent image is formed on the photosensitive drum 31 in this way, toner is supplied from the developing device 34 to the electrostatic latent image. When toner is supplied from the developing device 34, a toner image is formed on the photosensitive drum 31.

Then, the toner images on the respective photosensitive drums 31 are transferred to the paper by the transfer unit 4. The sheet on which the toner image is transferred is conveyed to the fixing unit 7 by the sheet conveying unit 6. After the toner image is fixed on the sheet by the fixing unit 7, the toner image is conveyed to the discharge unit 8. The sheet conveyed to the discharge unit 8 is discharged out of the multifunction machine 1.
The operation of supplying toner from the developing device 34 to the photosensitive drum 31 and the operation of collecting the reversely charged materials performed during the image forming operation will be described in detail below.
[Operation for supplying toner from developing device to photosensitive drum]
When supplying toner from the developing device 34 to the photosensitive drum 31, first, the second stirring screw 344 and the first stirring screw 343 rotate to stir the developer in the developing container 342. At this time, the carrier and the toner rub against each other, so that the toner is negatively charged (regularly charged toner). Here, the toner from which the external additive has been peeled off may be charged with a polarity (positive polarity) opposite to that of the normally charged toner (reversely charged toner). Also, the toner may be reversely charged by the depleted carrier.
The stirred developer is adsorbed to the sleeve 341b by the fourth pole 341f. At this time, a magnetic brush is formed on the sleeve 341b. The developer attached to the surface of the sleeve 341b of the developing roller 341 is transported to a position facing the photosensitive drum 31 as the sleeve 341b rotates.
Specifically, first, the developer attached to a position corresponding to the fourth pole 341f of the sleeve 341b is conveyed to a position corresponding to the third pole 341e of the sleeve 341b. At this time, the layer thickness of the developer on the sleeve 341b is regulated by the regulating member 345. That is, the length of the magnetic brush on the sleeve 341b is regulated. Then, the sleeve 341b further rotates, and the magnetic brush is conveyed to a position corresponding to the second pole 341d of the sleeve 341b. When the magnetic brush is transported to a position corresponding to the second pole 341d of the sleeve 341b, toner and paper powder that are reversely charged from the developer are collected by a collecting operation described in detail later.
Thereafter, the sleeve 341b further rotates, and the developer is conveyed from a position corresponding to the second pole 341d of the sleeve 341b to a position corresponding to the first pole 341c of the sleeve 341b. At this time, the state of FIG. 4A gradually changes to the state of (E). That is, at the position corresponding to the second pole 341d of the sleeve 341b, the reversely charged toner 91a is located farthest from the sleeve 341b (FIG. 4A) and gradually reversely charged as the sleeve 341b rotates. The toner 91a approaches the sleeve 341b (FIG. 4B). Then, the reversely charged toner 91a contacts the sleeve 341b ((C) in FIG. 4). Thereafter, the regular charged toner 91b that has been in contact with the sleeve 341b is separated from the sleeve 341b (FIG. 4D), and the regular charged toner 91b that has been in contact with the sleeve 341b is moved to the vicinity of the photosensitive drum 31 (see FIG. 4). 4 (E)). FIG. 4 schematically shows the position of the normally charged toner and the position of the reversely charged toner accompanying toner conveyance. In FIG. 4, the sleeve 341b is expressed in a flat plate shape in order to show how the magnetic brush moves as the sleeve 341b rotates. The position corresponding to the second pole 341d and the like of the sleeve 341b means a portion in contact with the second pole 341d and the like of the sleeve 341b.
Before the magnetic brush is conveyed to the position corresponding to the first pole 341c, the surface of the photosensitive drum 31 is negatively charged by the charging device 32. Then, the regular charged toner 91 b at the tip of the magnetic brush located at the position corresponding to the first pole 341 c of the sleeve 341 b moves to the photosensitive drum 31. In this way, the toner is supplied from the developing device 34 to the photosensitive drum 31.
After the toner on the sleeve 341b moves to the photosensitive drum 31, the sleeve 341b is further rotated. With the rotation of the sleeve 341b, the developer is conveyed to a position corresponding to the fifth pole 341g. Thereafter, the developer is conveyed into the developing container 342 as the sleeve 341b further rotates. Here, since the fourth pole 341f and the fifth pole 341g are the same magnetic pole, a repulsive force is generated between the fifth pole 341g and the fourth pole 341f. Therefore, the developer moves away from the sleeve 341b when the sleeve moves from a position corresponding to the fifth pole 341g of the sleeve to a position corresponding to the fourth pole 341f of the sleeve 341b.
[Operation for collecting reversely charged toner and paper powder and operation for removing reversely charged toner from the collecting member]
When the developer is transported to a position corresponding to the second pole 341d of the sleeve 341b as the sleeve 341b rotates, an operation of collecting reversely charged (plus charged) toner, paper dust, and the like is performed. Specifically, a switch is connected to the negative power source, and a negative voltage is applied to the collecting member 351. For this reason, reversely charged toner or paper dust is attracted to the collecting member 351.

  When the image forming operation is completed, the reversely charged toner collected by the collecting member 351 is removed from the collecting member 351. Specifically, the switch 352c is first connected to the positive power source 352a. A positive voltage is applied to the collecting member 351, and the toner and paper dust attached to the collecting member 35 are separated from the collecting member 351. Along with the rotation of the sleeve 341b, the magnetic brush formed on the sleeve 341b sweeps the toner and paper powder adsorbed on the collecting member 351 to the other end side of the suction duct 353. Then, toner, paper dust, and the like are sucked into the suction duct 353 by a suction device (not shown) and are attached to the suction filter 353c.

[effect]
Here, since the reversely charged toner and paper dust are collected before the developer is transported to the position facing the photosensitive drum 31, the reversely charged toner and paper dust are supplied to the photosensitive drum 31. Therefore, deterioration of image quality can be prevented.
Further, since the second pole 341d is disposed adjacent to the first pole 341c, the sleeve is not collected by the collecting member 351 when the developer is conveyed to a position corresponding to the second pole of the sleeve 341b. Even when a reversely charged toner or the like remains on 341b, it is positioned farthest from the photosensitive drum 31, that is, on the surface of the sleeve 341b when transported to the first pole 341c. The supply of reversely charged toner or the like can be further prevented.

  Here, as shown in FIG. 5, since the multifunction machine 1 includes the collecting member 351, the normally charged toner is easily located at the tip of the magnetic brush located at a position facing the photosensitive drum 31. For this reason, it is possible to prevent deterioration in image quality. The solid line in FIG. 5 indicates the charge distribution of the toner attached to the tip of the magnetic brush located at a position facing the photosensitive drum 31 disposed in the multi-function device 1 including the collecting member 351. 5 indicates the charge distribution of the toner attached to the tip of the magnetic brush located at a position facing the photosensitive drum 31 disposed in the multi-function peripheral that does not include the collecting member 351. The horizontal axis in FIG. 5 represents the charge amount around 100 μm, and the vertical axis represents the ratio (%).

  Since the collecting member 351 is disposed at a position where it can come into contact with the tip of the magnetic brush, the reversely charged toner or the like located at the tip of the magnetic brush can be easily attached to the collecting member 351. Further, reversely charged toner or the like attached to the surface of the collecting member 351 can be easily swept out.

  In addition, the said embodiment was used in order to demonstrate this invention, and unless it deviates from the range of invention, it shall accept | permit any design change, material change, etc.

[Other Embodiments]
(A) In the above-described embodiment, the apparatus using the toner is not described. However, the present invention is not limited to this, and the apparatus using the toner may be used. Specifically, the toner on the photosensitive drum 31 is cleaned by the drum cleaning device 36, and the cleaned toner is returned to the developing device 34 again. Further, a device that is charged again by the developing device 34 and reused for development may be used.
In this case, since the toner is charged more times than the apparatus that does not reuse the toner, the developer is easily deteriorated and effective.

  (B) In the above embodiment, the roller member 341a having five magnetic poles is used. However, the present invention is not limited to this, and a roller member 341a having more magnetic poles may be used. For example, an S pole and an N pole may be disposed between the second pole 341d and the third pole 341e.

  (C) Furthermore, in the above-described embodiment, the multifunction device 1 has been described. However, the present invention is not limited to this, and may be a copying machine, a printer, or the like.

  (D) In the above embodiment, the operation of removing the toner and the like from the collecting member 351 is performed after the end of the image forming operation. For example, it may be performed between jobs, in a state of waiting for a job, or during an image stabilization operation.

  (E) In the above embodiment, the apparatus provided with the removal mechanism has been described. However, the present invention is not limited to this, and the apparatus may not be provided with a mechanism for removing the reversely charged toner from the collecting member.

  (F) In the above embodiment, a configuration is adopted in which the normal charge is negative charge and the reverse charge is positive charge. However, the present invention is not limited to this, and the normal charge is positive charge and the reverse charge is negative charge. You may apply to the structure which becomes.

1 is an overall schematic cross-sectional view of a multifunction machine according to an embodiment of the present invention. The figure which shows the structure of a developing device and a collection mechanism. The figure which shows the state in which the spike of the developer is formed on the surface of the sleeve. The figure which shows the state of the magnetic brush from which a developer moves to the position corresponding to the 2nd pole of a sleeve from the position corresponding to the 1st pole of a sleeve. FIG. 4 is a diagram illustrating a ratio of toner supplied to a photosensitive drum.

Explanation of symbols

1 MFP (image forming device)
31 Photosensitive drum (image carrier)
34 Developing device 35 Collecting / removing mechanism 341 Developing roller 341a Roller member 341b Sleeve 341c 1st pole 341d 2nd pole 341e 3rd pole 341f 4th pole 341g 5th pole 342 Developing container 345 Restricting member 351 Collecting member 352 Voltage applying device 353 Suction Duct (discharge duct)

Claims (11)

An image forming apparatus that forms an image using a two-component developer,
An image carrier capable of carrying an electrostatic latent image on the surface;
A roller member having a first pole provided at a position facing the image carrier, and a second pole that is arranged side by side with the first pole in the circumferential direction and is opposite to the magnetic pole of the first pole; A developing roller having a sleeve that covers the roller member and conveys the developer to a position facing the image carrier, a developing container in which the developer can be stored, and the second electrode A regulating member that regulates the thickness of the developer layer conveyed to the position of the sleeve;
A collecting member that is disposed so as to face the second pole and collects a reversely charged reversely charged material;
An image forming apparatus.   The image forming apparatus according to claim 1, wherein the second pole is disposed adjacent to the first pole. The roller member is disposed adjacent to the second pole, and has a third pole having the same magnetic pole as the first pole at a position facing the regulating member.
The image forming apparatus according to claim 1. The collecting member has a conductive film member;
A voltage application device capable of applying a voltage to the conductive film member;
The voltage application device applies a voltage to the conductive film member so that the conductive film member attracts the reversely charged material during an image forming operation.
The image forming apparatus according to claim 1. The voltage application device applies a voltage to the conductive film member so that the reversely charged material is separated from the conductive film member during a non-image forming operation;
The image forming apparatus according to claim 4. The sleeve is a member capable of forming a magnetic brush on the surface,
The conductive film member is disposed at a position where it can contact the tip of a magnetic brush formed on the surface of the sleeve.
The image forming apparatus according to claim 5. It further has a removal mechanism capable of removing the reversely charged substance attached to the conductive film member,
The image forming apparatus according to claim 5. The removal mechanism includes a discharge duct capable of discharging the charged object to the outside of the developing device.
The image forming apparatus according to claim 7. The roller member is disposed adjacent to the third pole, and further includes a fourth pole for adsorbing the developer stored in the developer container to the surface of the sleeve;
The image forming apparatus according to claim 3. The roller member is disposed adjacent to the first pole, and further includes a fifth pole having the same magnetic pole as the second pole.
The image forming apparatus according to claim 3.   The image forming apparatus according to claim 3, wherein the roller member has only the second pole between the first pole and the third pole.

Images