Developing device that removes toner accumulated on top surface of regulating blade with simple configuration, and image forming apparatus including the same

A developing device includes a developing roller, a toner supply roller, a regulating blade, a casing, and a cleaning member. The developing roller supplies a toner to the image carrier in a region opposed to an image carrier. The toner supply roller is located opposed to the developing roller. The toner supply roller forms a magnetic brush made of a two-component developer including a magnetic carrier and a toner on an outer peripheral surface to supply a toner to the developing roller in a region opposed to the developing roller. The regulating blade is located opposed to the toner supply roller at a predetermined interval. The casing houses the developing roller, the toner supply roller, and the regulating blade. The cleaning member reciprocates along a longitudinal direction of the regulating blade so as to remove a toner accumulated on a top surface of the regulating blade.

INCORPORATION BY REFERENCE

This application is based upon, and claims the benefit of priority from, corresponding Japanese Patent Application No. 2016-133226 filed in the Japan Patent Office on Jul. 5, 2016, the entire contents of which are incorporated herein by reference.

BACKGROUND

A typical electrophotographic-method image forming apparatus irradiates a circumference surface of an image carrier (a photoreceptor drum) with a light based on image information read from a document image, or image information that is, for example, transmitted from an external device, such as a computer, to form a electrostatic latent image. After a toner is supplied to this electrostatic latent image from a developing device to form a toner image, this toner image is transferred on a paper sheet. The paper sheet after the transfer process is discharged to outside after a fixing process of the toner image is performed.

Recently, in association with progress of achieving color printing and high-speed processing, an image forming apparatus has become to have a complicated device configuration, while a toner stirring member needs to rotate at high speed in a developing device to meet the high-speed processing. Especially, in a development method that uses: a magnetic roller (toner supply roller) that uses a two-component developer including a magnetic carrier and a toner to carry the developer; and a developing roller that carries only the toner, a magnetic brush formed on the magnetic roller carries only the toner on the developing roller and, further, removes the toner, which has not been used for a development, from the developing roller in an opposing portion of the developing roller and the magnetic roller. Thus, in the proximity of the opposing portion of the developing roller and the magnetic roller, a toner float easily occurs, and then the floated toner is accumulated at the periphery of a trimming blade (regulating blade). When the accumulated toner condenses and attaches on the developing roller, a toner dropping occurs, and this may cause an image failure.

Here, for example, in a developing device that uses: a magnetic roller that uses a two-component developer including a magnetic carrier and a toner to carry the developer; and a developing roller that carries only the toner, there is proposed a developing device that includes a toner reception supporting member, a toner reception member, and vibration generating means. The toner reception supporting member is opposed to the developing roller or the magnetic roller. The toner reception member is located along a longitudinal direction of the toner reception supporting member and receives a toner that is dropped from the developing roller. The vibration generating means vibrates the toner reception member.

There is also proposed a developing device that includes a sheet-shaped vibration adjusting member located in both end portions of a toner reception supporting member in a longitudinal direction at a predetermined interval with a toner reception member. In this developing device, the toner reception member contacts the vibration adjusting member when the toner reception member vibrates. This causes the toner reception member to vibrate and wave while bending such that its free end of the toner reception member draws an arc, thus moving the toner accumulated on the free end side of the toner reception member to its fulcrum side.

SUMMARY

A developing device according to one aspect of the disclosure includes a developing roller, a toner supply roller, a regulating blade, a casing, and a cleaning member. The developing roller is located opposed to an image carrier on which an electrostatic latent image is formed. The developing roller supplies a toner to the image carrier in a region opposed to the image carrier. The toner supply roller is located opposed to the developing roller. The toner supply roller forms a magnetic brush made of a two-component developer including a magnetic carrier and a toner on an outer peripheral surface of the toner supply roller to supply a toner to the developing roller in a region opposed to the developing roller. The regulating blade is located opposed to the toner supply roller at a predetermined interval. The casing houses the developing roller, the toner supply roller, and the regulating blade. The cleaning member reciprocates along a longitudinal direction of the regulating blade so as to remove a toner accumulated on a top surface of the regulating blade.

DETAILED DESCRIPTION

The following describes embodiments of the disclosure with reference to the drawings.FIG. 1illustrates a schematic cross-sectional view illustrating an image forming apparatus (which is also referred to as color printer)100including developing devices3ato3dof the disclosure and illustrates a tandem type color printer here. The color printer100includes four image forming units Pa, Pb, Pc, and Pd in this order from an upstream side in a conveyance direction (a right side inFIG. 1) in its main body. These image forming units Pa to Pd are located corresponding to images of four different colors (cyan, magenta, yellow, and black), and sequentially form the images of cyan, magenta, yellow, and black through respective processes of charging, exposure, development, and transfer.

These image forming units Pa to Pd include photoreceptor drums1a,1b,1c,and1d,which carry visible images (toner images) of respective colors. Additionally, an intermediate transfer belt8, which rotates in a clockwise direction inFIG. 1, is located adjacent to the respective image forming units Pa to Pd.

When image data is input from a host apparatus such as a personal computer, first, chargers2ato2devenly charge the surfaces of the photoreceptor drums1ato1d,and then an exposure apparatus5irradiates the photoreceptor drums1ato1dwith light in accordance with the image data to form electrostatic latent images corresponding to the image data on the photoreceptor drums1ato1d.Toner containers4ato4dfill the developing devices3ato3dwith predetermined amounts of two-component developers (hereinafter also simply referred to as a developer) including toners of respective colors of cyan, magenta, yellow, and black. The toners in the developers are supplied and electrostatically attached onto the photoreceptor drums1ato1dby the developing devices3ato3d.This forms the toner images corresponding to the electrostatic latent images formed by the exposure by the exposure apparatus5.

Then, primary transfer rollers6ato6dapply electric fields at predetermined transfer voltages between the primary transfer rollers6ato6dand the photoreceptor drums1ato1d,and the toner images of cyan, magenta, yellow, and black on the photoreceptor drums1ato1dare primarily transferred on the intermediate transfer belt8. Cleaning units7ato7dremove a remnant toner or similar matter on a surface of the photoreceptor drums1ato1dafter the primary transfer.

Paper sheets P, on which toner images are to be transferred, are housed in a paper sheet cassette16located in a lower portion in the image forming apparatus100. The paper sheet P is conveyed to a nip portion (secondary transfer nip portion), which is formed between a secondary transfer roller9located adjacent to the intermediate transfer belt8and the intermediate transfer belt8, via a feed roller12aand a registration roller pair12bat a predetermined timing. The transferred paper P on which the toner images have been secondarily transferred is conveyed to a fixing unit13.

The transferred paper P conveyed to the fixing unit13is heated and pressured by a fixing roller pair13a.Then the toner image is fixed on a surface of the paper sheet P, thus forming a predetermined full-color image. The transferred paper P, on which the full-color image is formed, is discharged to a discharge tray17by a discharge roller pair15.

FIG. 2illustrates a cross-sectional side view illustrating the developing device3aaccording to a first embodiment of the disclosure, andFIG. 3illustrates a front view when the developing device3aof the first embodiment is viewed from a right direction inFIG. 2.FIG. 2illustrates a state viewed from a back side inFIG. 1, and locations of respective members, which are in the developing device3a,are reversed with respect to a right and a left inFIG. 1. While the following describes the developing device3alocated in the image forming unit Pa ofFIG. 1as an example, configurations of the developing device3bto3dlocated in the image forming units Pb to Pd are basically identical, and thus their description will be omitted.

As illustrated inFIG. 2, the developing device3aincludes a developing container (which is also referred to as casing)20that houses the two-component developer (hereinafter also simply referred to as a developer). The developing container20is partitioned into a stir conveyance chamber (which is also referred to as first conveyance chamber)21and a supply conveyance chamber (which is also referred to as second conveyance chamber)22by a partition wall20a.In the stir conveyance chamber21and the supply conveyance chamber22, a stir conveyance screw (which is also referred to as first stirring member)25aand a supply conveyance screw (which is also referred to as second stirring member)25bare each rotatably arranged. The stir conveyance screw25aand the supply conveyance screw25bmix the toner (a positively charged toner) supplied from the toner container4a(seeFIG. 1) with a carrier, and stir and charge the toner.

Then, the developer is conveyed in an axial direction (a direction orthogonal to a paper surface ofFIG. 2) while being stirred by the stir conveyance screw25aand the supply conveyance screw25b.The developer is circulated between the stir conveyance chamber21and the supply conveyance chamber22via developer passing portions20eand20f(seeFIG. 10) that are formed on both end portions of the partition wall20a.That is, the stir conveyance chamber21, the supply conveyance chamber22, and the developer passing portions20eand20fform a circulation route of the developer in the developing container20.

The developing container20obliquely extends toward an upper right inFIG. 2. A toner supply roller30(developer carrier) is located above the supply conveyance screw25bin the developing container20. A developing roller31is obliquely located above an upper right of the toner supply roller30and opposed to the toner supply roller30. Then, the developing roller31is opposed to the photoreceptor drum1a(seeFIG. 1) on an opening side (a right side inFIG. 2) of the developing container20, and the toner supply roller30and the developing roller31rotate about respective rotation axes in an anticlockwise direction inFIG. 2.

The stir conveyance chamber21includes a toner density sensor (not illustrated) opposed to the stir conveyance screw25a.The toner density sensor detects a proportion (T/C) of the toner to the carrier in the developer. The stir conveyance chamber21is replenished with the toner from the toner container4avia a toner replenishment port20con the basis of a detection result of the toner density sensor. As the toner density sensor, for example, a magnetic permeability sensor that detects magnetic permeability of the two-component developer, which is constituted of the toner and a magnetic carrier, in the developing container20is employed.

The toner supply roller30is constituted of a non-magnetic rotation sleeve and a fixed magnet body. The rotation sleeve rotates in the anticlockwise direction inFIG. 2. The fixed magnet body has a plurality of magnetic poles internally included in the rotation sleeve.

The developing roller31is constituted of a cylindrically-shaped development sleeve and a developing-roller-side-magnetic pole. The development sleeve rotates in the anticlockwise direction inFIG. 2. The developing-roller-side-magnetic pole is secured into the development sleeve. The toner supply roller30and the developing roller31are opposed to one another at their facing positions (opposing positions) at a predetermined clearance. The developing-roller-side-magnetic pole has a polarity different from a magnetic pole (main pole) opposed to the fixed magnet body.

In the developing container20, a trimming blade33(regulating blade) is mounted along a longitudinal direction (the direction orthogonal to the paper surface ofFIG. 2) of the toner supply roller30. The trimming blade33is located on an upstream side with respect to the opposing position of the developing roller31and the toner supply roller30in a rotation direction (the anticlockwise direction inFIG. 2) of the toner supply roller30. Then, a slight gap is formed between a distal end portion of the trimming blade33and a surface of the toner supply roller30.

A DC voltage (hereinafter referred to as Vslv (DC)) and an AC voltage (hereinafter referred to as Vslv (AC)) are applied to the developing roller31. A DC voltage (hereinafter referred to as Vmag (DC)) and an AC voltage (hereinafter referred to as Vmag (AC)) are applied to the toner supply roller30. These DC voltages and AC voltages are applied to the developing roller31and the toner supply roller30via a bias control circuit from a developing bias power source (each of components is not illustrated).

As described above, the developer is circulated in the stir conveyance chamber21and the supply conveyance chamber22, which are in the developing container20, while being stirred by the stir conveyance screw25aand the supply conveyance screw25b.Then, the toners in the developer are charged, and the developer is conveyed to the toner supply roller30by the supply conveyance screw25b.Then, a magnetic brush (not illustrated) is formed on the toner supply roller30. The trimming blade33regulates a layer thickness of the magnetic brush on the toner supply roller30. After that, the rotation of the toner supply roller30conveys the magnetic brush to an opposing portion of the toner supply roller30and the developing roller31. Then, an electric potential difference ΔV between Vmag (DC) applied to the toner supply roller30and Vslv (DC) applied to the developing roller31, and a magnetic field form a thin toner layer on the developing roller31.

While a toner layer thickness on the developing roller31changes due to, for example, a resistance of the developer, and a rotation speed difference between the toner supply roller30and the developing roller31, the toner layer thickness is controlled by ΔV. When ΔV is increased, the toner layer on the developing roller31becomes thick. When ΔV is reduced, the toner layer becomes thin. An appropriate range of ΔV during the development is, typically, around 100 V to 350 V.

The rotation of the developing roller31conveys the thin toner layer formed on the developing roller31by a contact with the magnetic brush on the toner supply roller30to the opposing portion (an opposing region) of the photoreceptor drum1aand the developing roller31. Vslv (DC) and Vslv (AC) are applied to the developing roller31, and thus an electric potential difference between the photoreceptor drum1aflies the toner to develop an electrostatic latent image on the photoreceptor drum1a.

The toner left on the developing roller31, which has not been used in the development, is conveyed to the opposing portion of the developing roller31and the toner supply roller30again by the rotation of the developing roller31, and then is recovered by the magnetic brush on the toner supply roller30. Then, the magnetic brush is dropped into the supply conveyance chamber22after being removed from the toner supply roller30at an identical pole portion of the fixed magnet body.

After that, a toner in a predetermined amount is replenished on the basis of a detection result of the toner density sensor (not illustrated) from a toner replenishment port (not illustrated), so as to generate the two-component developer, which is uniformly charged at an appropriate toner density again, while circulating in the supply conveyance chamber22and the stir conveyance chamber21. This developer is supplied onto the toner supply roller30by the supply conveyance screw25bagain to form the magnetic brush, so as to be conveyed to the trimming blade33.

A cleaning member35that removes the toner accumulated on a top surface of the trimming blade33is located at a proximity of the developing roller31on a right side wall of the developing container20inFIG. 2. As illustrated inFIG. 2, the cleaning member35is located inside a wall portion37inclining downward toward the toner supply roller30direction from the developing roller31in the developing container20. The cleaning member35enables the reciprocation along a longitudinal direction (the direction orthogonal to the paper surface ofFIG. 2) of the trimming blade33. The cleaning member35is located at a reference position on one end side of (a far-side of the paper surface ofFIG. 2) of the longitudinal direction of the trimming blade33in a standby state.

As illustrated inFIG. 3, a connecting portion20b,which is connected to a toner conveyance path38, is formed in one end portion of a longitudinal direction of the developing container20. The connecting portion20bis formed in an end portion of a downstream side (a left side inFIG. 3) with respect to a movement direction from the reference position of the cleaning member35, and the toner removed from the trimming blade33by the cleaning member35is conveyed to a toner recovery container39via the toner conveyance path38.

FIGS. 4 and 5obliquely illustrate a driving mechanism of the cleaning member35employed in the developing device3aof the first embodiment.FIG. 4illustrates a state where the cleaning member35is located on one end side (the reference position) of the trimming blade33.FIG. 5illustrates a state where the cleaning member35has been moved to the other end side.FIG. 6illustrates a side view illustrating the trimming blade33and the cleaning member35viewed from a downstream side (a left side inFIG. 5) of the movement direction of the cleaning member35.FIG. 7schematically illustrates a perspective view illustrating a state where the cleaning member35recovers the toner accumulated on the top surface of the trimming blade33.

As illustrated inFIG. 4, the cleaning member35includes a cylindrically-shaped supporting portion35a,a cleaning portion35b,and a regulating portion35c.The supporting portion35ais externally inserted into a shaft40. The cleaning portion35bextends along the top surface of the trimming blade33from the supporting portion35a.The regulating portion35cprojects in a direction opposite to the cleaning portion35bfrom the supporting portion35a.

While a material of the cleaning member35is not specifically limited, it is necessary that a material having a small friction coefficient with respect to the metallic trimming blade33be employed in order to smoothly slide the cleaning member35along the top surface of the trimming blade33. Specifically, a common resin material, such as polyethylene resin and polypropylene resin, can be employed.

When the cleaning portion35bis extended up to a distal end of the trimming blade33so as to remove the toner accumulated on an edge portion of the distal end of the trimming blade33, the cleaning portion35bhaving a high rigidity may strip the magnetic brush formed on an outer peripheral surface of the toner supply roller30or damage the toner supply roller30. Thus, in a distal end of the cleaning portion35b,a flexibility sheet member41is provided. This configuration ensures removing the toner accumulated on the edge portion of the distal end of the trimming blade33without generating the striped magnetic brush or the damaged toner supply roller30.

The sheet member41is located such that the sheet member41contacts the magnetic brush formed on the outer peripheral surface of the toner supply roller30. Urethane or PET (polyethylene terephthalate) is preferred as a material of the sheet member41in order that the sheet member41lightly contacts to the extent that the magnetic brush of the toner supply roller30is not stripped. While the sheet member41may be located such that a distal end of the sheet member41contacts the toner supply roller30, in this case, it is necessary that the material and a thickness of the sheet member41be adjusted such that the toner supply roller30is not damaged. It is preferred that the thickness of the sheet member41be 50 μm to 300 μm in the case of a urethane sheet and be around 50 μm to 200 μm in the case of a PET sheet.

The shaft40, which is internally inserted into the supporting portion35aof the cleaning member35, has an outer peripheral surface on which a spiral groove portion40ais formed. An inner circumference surface of the supporting portion35aincludes a spiral protrusion (not illustrated) that engages the groove portion40a.A driving input gear43is secured to one end of the shaft40, and the driving input gear43receives a driving power of a motor51(seeFIG. 8) via gears45and47.

Next, the following describes a clean operation where the cleaning member35removes the toner accumulated on the top surface of the trimming blade33. As described above, the toner, which has not been used for the development and is on the developing roller31, is removed at the opposing portion of the toner supply roller30and the developing roller31from the developing roller31, and then is recovered by the magnetic brush on the toner supply roller30. At this time, a part of the toner removed from the developing roller31is dropped without being recovered by the magnetic brush. The dropped toner slides off along an incline of the wall portion37(seeFIG. 2) to be accumulated near a distal end portion of the top surface of the trimming blade33.

Thus, as illustrated inFIG. 5, when an image is not formed and when the motor51is driven to rotate the gear47in an anticlockwise direction, the gear45connected to the gear47rotates in a clockwise direction, causing the driving input gear43connected to the gear45to rotate in the anticlockwise direction. This rotates also the shaft40to which the driving input gear43is secured in an anticlockwise direction inFIG. 5, causing a phase of the spiral groove portion40a,which is formed on the shaft40, to move in an arrow-A direction. Consequently, in association with the moved phase of the groove portion40a,the cleaning member35, which engages the groove portion40ain the supporting portion35a,moves from the reference position (a right end inFIG. 3) up to the other end side of the trimming blade33(a left end inFIG. 3) in the arrow-A direction. At this time, as illustrated inFIG. 6, the cleaning member35is held in a posture where the anticlockwise rotation of the shaft40presses the cleaning portion35bto the top surface of the trimming blade33.

As illustrated inFIG. 7, the movement of the cleaning member35causes the cleaning portion35band the sheet member41to scrape a toner T accumulated on the top surface of the trimming blade33. The scraped toner moves in the longitudinal direction of the trimming blade33to convey outside the developing container20from an end portion of the trimming blade33via the toner conveyance path38, so as to be recovered by the toner recovery container39.

After that, when the inverted driving of the motor51rotates the gear47in the clockwise direction, the gear45connected to the gear47rotates in the anticlockwise direction, causing the driving input gear43connected to the gear45rotate in the clockwise direction. This rotates also the shaft40, to which the driving input gear43is secured, in the clockwise direction inFIG. 5, causing the phase of the spiral groove portion40a,which is formed on the shaft40, to move in an arrow-A′ direction.

As illustrated inFIG. 6, on an inner surface of the developing container20, a stepped portion48is formed along the longitudinal direction of the trimming blade33. The clockwise rotation of the shaft40causes the regulating portion35cof the cleaning member35to abut on the stepped portion48. This holds the cleaning member35in a posture where the cleaning portion35bcontacts the trimming blade33as illustrated inFIG. 6without corotation along with the shaft40in the clockwise direction. As a result, in association with the moved phase of the groove portion40a,the cleaning member35moves up to the reference position (the position inFIG. 4) from the position inFIG. 5in the arrow-A′ direction to be returned into the standby state.

In the configuration of the embodiment, the cleaning member35scrapes the toner accumulated on the top surface of the trimming blade33to ensure the reduction of the toner accumulated on the top surface of the distal end of the trimming blade33. Consequently, this ensures the effectively reduced generation of toner drop due to an attachment of the toner accumulated on the top surface of the distal end of the trimming blade33on the magnetic brush of the toner supply roller30during the image formation, and an additional attachment on the developing roller31.

The cleaning member35waits at the reference position (the position inFIG. 4) that is not opposed to the outer peripheral surface of the toner supply roller30except when removing the toner accumulated on the top surface of the trimming blade33. This eliminates the possibility that the image is adversely affected because the sheet member41of the cleaning member35contacts the magnetic brush of the toner supply roller30during the image formation.

As a timing of moving the cleaning member35, the movement may be performed at a predetermined timing, such as each time a printing operation is terminated, a time point when the number of printed sheets reaches the predetermined number of printed sheets, and a time point when a temperature in the developing device3ais equal to or more than a predetermined temperature. The cleaning member35is moved every time the number of printed sheets reaches the predetermined number, causing the cleaning member35to automatically perform cleaning in accordance with the number of printed sheet. Thus, it is not necessary for the user to perform manual setting for cleaning by the cleaning member35by himself/herself. This ensures the reduction of setting error, forgetting the setting, or performing unnecessary cleaning.

The toner removed from the top surface of the trimming blade33by the cleaning member35is recovered by the toner recovery container39via the toner conveyance path38without being returned into the supply conveyance chamber22. Thus, this ensures the effectively reduced generation of scattered toner particles or a fog image due to reuse of a toner having a low charge amount or a reversely charged toner, which is accumulated on the top surface of the trimming blade33, for a development.

FIG. 8obliquely illustrates a transmission mechanism of a driving power from the motor51to the shaft40.FIG. 8illustrates the transmission mechanism of the driving power to the shaft40(a left side inFIG. 8) of the developing device3aand a shaft40(a right side inFIG. 8) of the developing device3b.Driving input gears43of respective shafts40are connected to spur portions50aof worm gears50via the gears45and47.

A pinion gear53secured to an output shaft of the motor51is connected to one of the worm gears50. Thus, a rotary drive power of the motor51has a transmission direction perpendicularly converted via the worm gear50to be transmitted to the shaft40(a left side inFIG. 8) of the developing device3avia the gears47and45and the driving input gear43.

The respective worm gears50connect to drive transmission gears55where the respective worm gears50and rotation axis are orthogonal. The respective drive transmission gears55are secured to a common rotation shaft60. The developing devices3cand3dalso include transmission mechanisms (not illustrated here) of the driving power to the shafts40having an identical configuration, and the rotary drive power of the motor51is transmitted to the worm gears50via the drive transmission gears55secured to the rotation shaft60.

The configuration illustrated inFIG. 8ensures the simultaneous operation of cleaning members35in the developing devices3ato3dusing the one motor51. This eliminates the need for separately disposing a motor for moving the cleaning members35in the respective developing devices3ato3d,thus ensuring the simplified control path.

FIG. 9illustrates a cross-sectional side view near the toner replenishment port20cof the developing device3aaccording to a second embodiment of the disclosure.FIG. 10illustrates a cross-sectional plan view (a cross-sectional view taken along the line X-X inFIG. 9) illustrating a stirring portion in the developing device3aof the second embodiment. The developing device3aof the embodiment includes a conveyance spiral70and a toner recovery path71. The conveyance spiral70conveys the toner removed from the top surface of the trimming blade33by the cleaning member35. The toner recovery path71returns the toner removed by the conveyance spiral70to the stir conveyance chamber21. Configurations of the other portions of the developing device3a,such as the cleaning member35and the driving mechanism of the cleaning member35, are similar to the first embodiment.

As illustrated inFIG. 9, the toner replenished via the toner replenishment port20cfrom the toner container4a(seeFIG. 1) passes through an inside of a toner replenishment path20dto reach a replenished-toner conveyance screw25c.As illustrated inFIG. 10, the replenished-toner conveyance screw25cis formed coaxially with a rotation axis of the stir conveyance screw25aon an upstream side (a right side inFIG. 10) of a conveyance direction of the stir conveyance screw25a.The replenished toner is handed over to the stir conveyance screw25aby the replenished-toner conveyance screw25cto be conveyed to an inside of the stir conveyance chamber21in an arrow-X direction while being mixed with the carrier in the stir conveyance chamber21, so as to be charged at a predetermined charge amount.

The conveyance spiral70and the toner recovery path71are located on the downstream side (a paper-surface-front side inFIG. 9) of the movement direction of the cleaning member35. A lower end portion of the toner recovery path71communicates with the toner replenishment path20d.A rotation of the conveyance spiral70moves the toner removed from the top surface of the trimming blade33by the cleaning member35inside the toner recovery path71to be conveyed to the inside of the toner replenishment path20d.Then, this toner reaches the replenished-toner conveyance (stirring) screw25cafter being joined to the replenished toner, which passes through the inside of the toner replenishment path20d.

According to the configuration of the embodiment, the toner removed from the top surface of the trimming blade33passes through the toner recovery path71, and then is recovered at an end portion (a right edge inFIG. 10) of an upstream side with respect to a developer conveyance direction in the stir conveyance chamber21. Thus, the toner having a low charge amount or the reversely charged toner, which is accumulated on the top surface of the trimming blade33, is sufficiently mixed with the carrier while being stirred and conveyed from one end side (the right edge inFIG. 10) of a longitudinal direction of the stir conveyance chamber21to the other end side (a left side inFIG. 10). Then, the toner passes through the developer passing portion20eto be conveyed to the supply conveyance chamber22after a uniform charge. After that, in the supply conveyance chamber22, the toner is supplied to the toner supply roller30to be used for a development again.

Thus, this ensures the effectively reduced generation of scattered toner particles or a fog image due to use of the toner having a low charge amount or the reversely charged toner for a development after the supply to the toner supply roller30. Additionally, the reusability of the toner removed from the top surface of the trimming blade33for a development ensures the reduced waste toner and eliminates the need for disposing the toner recovery container39that recovers the waste toner.

The disclosure is not limited to the above-described respective embodiments and can be variously modified without departing from the spirit of the disclosure. For example, the shape and the configuration of the cleaning member35, which are described in the above-described respective embodiments, are examples, are not particularly limited to the above-described embodiments, and these are appropriately determined corresponding to, for example, a device configuration.

For example, while the above-described respective embodiments include a configuration where the rotation of the shaft40having the outer peripheral surface on which the spiral groove portion40ais formed reciprocates the cleaning member35, a rack-and-pinion mechanism that is constituted of a rack gear and a pinion gear that meshes with the rack gear instead of the shaft40may be employed so as to reciprocate the cleaning member35.

While in the above-described respective embodiments the disclosure is applied to the developing devices3ato3d,which use the two-component developers, form the magnetic brush on the toner supply roller30, move only toners to the developing roller31from the toner supply roller30, and then supply the toners to the photoreceptor drums1ato1dfrom the developing roller31, in addition, as illustrated inFIG. 11, the disclosure is also applicable to a developing device where the developing roller31and the toner supply roller30are positioned reversely to the above-described embodiments. In this developing device, the magnetic brush made of the two-component developer that is held on a surface of the developing roller31(that is a magnetic roller having the configuration similar to the toner supply roller30of the above-described embodiments in the configuration) supplies toners to the photoreceptor drums1ato1d.Then, the toner held on the surface of the toner supply roller30(that has the configuration similar to the developing roller31of the above-described embodiments in the configuration) is supplied to the developing roller31, and a surplus toner, which is on the surface of the developing roller31, is recovered using the toner supply roller30. Even this configuration ensures the effective reduction of the toner dropped from the developing roller31is accumulated on the periphery of the trimming blade33, which is opposed to the toner supply roller30.

The disclosure is applicable to a developing device that includes a wall portion opposed to a developing roller between an opposing region of an image carrier and the developing roller, and a regulating blade. Use of the disclosure ensures providing that includes: a developing device that removes the toner accumulated on a top surface of a regulating blade regardless of fluidity of a toner with a simple constitution; and an image forming apparatus including the same.