JP4743857B2 - Developer transport device and image forming apparatus - Google Patents

Description

  The present invention relates to a developer transport device for transporting a developer to a predetermined transport destination in an image forming apparatus using an electrophotographic system such as a copying machine, a printer, a facsimile machine, or a composite machine thereof, and an image forming apparatus including the developer transport device. More particularly, the present invention relates to a developer conveying device and an image forming apparatus for transferring a new carrier and toner toward the developing device.

  2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic system such as a copying machine or a printer, a developing unit that contains a two-component developer composed of toner and a carrier (including cases where an additive or the like is added) A technique (referred to as trickle development method) in which a new carrier is appropriately replenished and the developer is replaced is known (for example, see Patent Document 1).

  In the developing unit using the two-component developer, toner is appropriately supplied into the developing unit from a toner supply port provided in a part of the developing unit in accordance with toner consumption in the developing unit. The replenished toner is stirred and mixed by a stirring member such as a transport screw together with the developer in the developing unit. Part of the stirred and mixed developer is supplied to the developing roller. After the developer carried on the developing roller is regulated to an appropriate amount by the doctor blade, the toner in the two-component developer adheres to the latent image on the photosensitive drum at a position facing the photosensitive drum.

  As described above, the carrier in the two-component developer accommodated in the developing unit in the normal developing process remains in the developing unit without being consumed, and thus the carrier deteriorates with time. Specifically, the carrier is agitated and mixed for a long time in the developing part, and the coating layer of the carrier wears or peels off, resulting in a “film scraping phenomenon” in which the charging ability of the carrier is reduced, or a toner component on the surface of the carrier. In addition, the “spent phenomenon” in which the charging ability of the carrier is reduced due to the adhesion of additives.

The trickle development method is for preventing the deterioration of the image quality of the output image due to such deterioration of the carrier over time. That is, a new carrier (or a new two-component developer) is appropriately replenished in the developing unit, and a part of the two-component developer accommodated in the developing unit is appropriately discharged to the outside of the developing unit. The amount of deteriorated carriers is reduced to maintain the amount of carriers accommodated in the developing unit and the charging ability.
An image forming apparatus using such a trickle development method is more time-consuming than an apparatus in which the developing unit and the carrier need to be replaced with new ones when the deterioration of the carrier over time becomes unacceptable. Also, the image quality of the output image will be stabilized.

  Japanese Patent Application Laid-Open No. H11-133959 discloses an image forming apparatus using a trickle developing method, in which toner is stored in a toner storage unit (toner storage container) and carrier stored in a carrier storage unit (carrier storage container). And a developer conveying device that conveys the toner to a developing unit using a screw pump (Mono pump). Such a developer transport device includes a flexible transport pipe (tube) in a developer transport path between a toner container and carrier container serving as a developer transport source, and a developer serving as a developer transport destination. ), The stress applied to the developer during transport is less, and the degree of freedom in the layout of the entire image forming apparatus is also improved, compared to a device that forms a developer transport path with a hollow pipe having a coil screw. It is known.

JP 2005-195659 A

The technology disclosed in Patent Document 1 described above transports carrier and toner in the transport pipe by sending (or feeding) gas in the transport pipe by a screw pump to generate negative pressure (or positive pressure) in the transport pipe. It is something to be made.
However, the technique disclosed in Patent Document 1 has a problem that the carrier is deposited on the bottom of the transport pipe with time. This is because the carrier and toner are transported through the transport tube in a state where the carrier and toner are not sufficiently dispersed and mixed, so that the carrier having a high specific gravity separates from the toner and moves to the bottom of the transport tube.

  When the carrier is thus deposited on the bottom of the transport pipe, the negative pressure (or positive pressure) generated by the screw pump causes toner with a low specific gravity to be mainly transferred to the developing unit, which prevents the carrier from being supplied to the developing unit. It will be enough. Further, in the transport path against gravity (such as an inclined path from a low position to a high position), carrier deposition is particularly likely to occur, and the transport pipe may be blocked. Further, such a problem cannot be ignored particularly when the transport route by the transport pipe is set long.

  In order to solve such a problem, a measure for increasing the pressure generated in the conveying pipe by the screw pump is also conceivable. However, in this case, new problems such as an increase in the size and cost of the apparatus and an increase in the internal pressure of the developing unit occur.

  Such a problem is not limited to the developer conveying device that conveys the carrier accommodated in the carrier accommodating portion and the toner accommodated in the toner accommodating portion, and the two-component developer accommodated in the two-component developer accommodating portion. This is also common to the developer conveying device that conveys the toner and the developer conveying device that conveys only the carrier accommodated in the carrier accommodating portion. In addition, this problem is also common to some extent in the developer transport device that transports only the toner stored in the toner storage unit.

  The present invention has been made to solve the above-described problems, and without causing damage to the developer, the degree of freedom in layout is relatively high, and the transport pipe is blocked with a relatively simple configuration. It is another object of the present invention to provide a developer conveying device and an image forming apparatus that efficiently and reliably convey the developer.

A developer conveying device according to a first aspect of the present invention is a developer conveying device that conveys a developer composed of toner and a carrier, and the developer is supplied together with a gas fed or delivered by a pump. A transport pipe to be transported, a porous member arranged in a single or plural manner so as to cover a part or all of the outer periphery of the transport pipe in the path of the transport pipe, and the transport pipe via the porous member An air supply means for supplying gas into the interior of the printer , wherein the transport pipe supplies a toner discharge port for discharging the toner stored in the toner storage portion and a carrier supply for supplying the carrier stored in the carrier storage portion And at least one of the porous members disposed in the vicinity of the carrier supply port .

According to a second aspect of the present invention, there is provided the developer conveying device according to the first aspect, wherein the toner containing portion is interposed via a second porous member disposed in the vicinity of the toner discharge port. Is provided with a second air feeding means for feeding gas into the interior.

According to a third aspect of the present invention, in the developer conveying device according to the second aspect, the conveying tube is provided with the toner discharge port and is detachably inserted into the toner accommodating portion. The nozzle is provided, and the second air feeding means is configured to feed gas into the nozzle through the second porous member.

Further, the developer conveying device according to a fourth aspect of the invention, in the invention according to claim 2, wherein the second porous member, distribution at a position embedded in the toner accommodated in the toner accommodating portion It was established.

According to a fifth aspect of the present invention, there is provided the developer conveying device according to any one of the first to fourth aspects, wherein the carrier replenishing port is closed when the air supply means is operating. To do.

According to a sixth aspect of the present invention, in the developer conveying device according to the first to fifth aspects, the pump is operated after the operation of the air supply means is completed. Is.

According to a seventh aspect of the present invention, there is provided the developer transport device according to any one of the first to sixth aspects, wherein the pump is a screw pump that sends the developer together with the gas from the transport pipe. It is what.

According to an eighth aspect of the present invention, there is provided the developer conveying device according to any one of the first to seventh aspects, wherein the conveying tube accommodates toner and a carrier and an image carrier. The developer is conveyed toward a developing unit that develops the latent image formed thereon.

According to a ninth aspect of the present invention, there is provided the developer conveying device according to the eighth aspect , wherein the developing section discharges the toner and a part of the carrier contained therein. It is equipped with.

Further, in the developer conveying device according to the invention of claim 10, in the invention of any one of claims 1 to 9, the porous member has an opening ratio of 5 to 40%. It is formed.

The developer conveying device according to the invention of claim 11 is the invention according to any one of claims 1 to 10 , wherein the porous member has an average opening diameter of 0.3 to 20 μm. It is formed as follows.

The developer conveying device according to a twelfth aspect of the present invention is the developer conveying device according to any one of the first to eleventh aspects, wherein the porous member has an average pore diameter of a toner volume. It is formed so as to be 0.1 to 5 times the average particle size.

According to a thirteenth aspect of the present invention, an image forming apparatus includes the developer conveying device according to any one of the first to thirteenth aspects.

  In this application, “developer” is an agent used in the development process, and is a general term for all of “carrier”, “toner”, “two-component developer composed of carrier and toner”, and the like. Define that there is.

  In the present invention, the gas is fed into the inside of the transport pipe through one or more porous members disposed in the path of the transport pipe. As a result, the developer transport device can transport the developer efficiently and reliably without damaging the developer, having a relatively high degree of freedom in layout, and having a relatively simple configuration without blocking the transport pipe. In addition, an image forming apparatus can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

Embodiment 1 FIG.
A first embodiment of the present invention will be described in detail with reference to FIGS.
First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.
In FIG. 1, 1 is an apparatus main body of a color copying machine as an image forming apparatus, 2 is a writing unit that emits laser light based on input image information, and 20Y, 20M, 20C, and 20BK are colors (yellow, magenta, cyan, black). ), A photosensitive drum as an image carrier accommodated in each of the process cartridges 20Y, 20M, 20C, and 20BK, 22 is a charging unit that charges the photosensitive drum 21, and 23Y, 23M, Reference numerals 23C and 23BK denote developing units (developing devices) for developing the electrostatic latent image formed on the photosensitive drum 21, and reference numeral 24 denotes a transfer bias for transferring the toner image formed on the photosensitive drum 21 to the intermediate transfer belt 27. A roller 25 indicates a cleaning unit that collects untransferred toner on the photosensitive drum 21.

  In addition, 27 is an intermediate transfer belt on which toner images of a plurality of colors are transferred in an overlapping manner, 28 is a second transfer bias roller for transferring the toner image formed on the intermediate transfer belt 27 to the recording medium P, and 29 is an intermediate transfer belt. 27 is an intermediate transfer belt cleaning unit that collects untransferred toner, 30 is a conveyance belt that conveys a recording medium P on which a four-color toner image is transferred, and 32Y, 32M, 32C, and 32BK are developing units 23Y and 23M. , 23C and 23BK, a toner replenishing unit for replenishing each color toner, 47Y, 47M, 47C and 47BK are carrier replenishing units for newly replenishing each developing unit 23Y, 23M, 23C and 23BK, and 51 is a document D A document conveying unit that conveys the document to the reading unit 55, 55 a document reading unit (scanner) that reads image information of the document D, and 61 a recording medium P such as transfer paper. A paper feeding unit to be accommodated, 66 a fixing unit for fixing an unfixed image on the recording medium P, and 85 a toner container holding unit in which toner cartridges of the toner replenishing units 32Y, 32M, 32C, and 32BK are detachably installed. , 86 indicates a carrier container holding portion in which the carrier cartridges of the carrier replenishing portions 47Y, 47M, 47C, 47BK are detachably installed.

Here, each of the process cartridges 20Y, 20M, 20C, and 20BK is obtained by integrating the photosensitive drum 21, the charging unit 22, and the cleaning unit 25, respectively.
Image formation of each color (yellow, magenta, cyan, black) is performed on the photosensitive drum 21 in each of the process cartridges 20Y, 20M, 20C, and 20BK.

Hereinafter, an operation during normal color image formation in the image forming apparatus will be described.
First, the document D is transported from the document table in the direction of the arrow in the drawing by the transport roller of the document transport unit 51 and placed on the contact glass 53 of the document reading unit 55. Then, the document reading unit 55 optically reads the image information of the document D placed on the contact glass 53.

  Specifically, the document reading unit 55 scans the image of the document D on the contact glass 53 while irradiating light emitted from the illumination lamp. Then, the light reflected by the document D is imaged on the color sensor via the mirror group and the lens. The color image information of the document D is read for each RGB (red, green, blue) color separation light by the color sensor, and then converted into an electrical image signal. Further, an image processing unit (not shown) performs color conversion processing, color correction processing, spatial frequency correction processing, and the like on the basis of RGB color separation image signals, so that yellow, magenta, cyan, and black are processed. Get color image information.

  Then, the image information of each color of yellow, magenta, cyan, and black is transmitted to the writing unit 2. Then, laser light (exposure light) based on the image information of each color is emitted from the writing unit 2 toward the photosensitive drums 21 of the corresponding process cartridges 20Y, 20M, 20C, and 20BK.

On the other hand, the four photosensitive drums 21 rotate in the clockwise direction in FIG. First, the surface of the photosensitive drum 21 is uniformly charged at a position facing the charging unit 22 (a charging process). Thus, a charged potential is formed on the photosensitive drum 21. Thereafter, the surface of the charged photosensitive drum 21 reaches the irradiation position of each laser beam.
In the writing unit 2, laser light corresponding to the image signal is emitted from the light source corresponding to each color. The laser light is incident on the polygon mirror 3 and reflected, and then passes through the lenses 4 and 5. The laser light after passing through the lenses 4 and 5 passes through different optical paths for each of the yellow, magenta, cyan, and black color components (this is an exposure process).

  The laser beam corresponding to the yellow component is reflected by the mirrors 6 to 8 and then irradiated onto the surface of the photosensitive drum 21 of the first process cartridge 20Y from the left side of the drawing. At this time, the yellow component laser light is scanned in the rotation axis direction (main scanning direction) of the photosensitive drum 21 by the polygon mirror 3 that rotates at high speed. Thus, an electrostatic latent image corresponding to the yellow component is formed on the photosensitive drum 21 charged by the charging unit 22.

  Similarly, the laser beam corresponding to the magenta component is reflected by the mirrors 9 to 11 and then irradiated to the surface of the photosensitive drum 21 of the second process cartridge 20M from the left side of the paper, thereby causing an electrostatic latent image corresponding to the magenta component. An image is formed. The cyan component laser light is reflected by the mirrors 12 to 14 and then irradiated to the surface of the photosensitive drum 12 of the third process cartridge 20C from the left side of the drawing to form a cyan component electrostatic latent image. The black component laser light is reflected by the mirror 15 and then irradiated on the surface of the photosensitive drum 21 of the fourth process cartridge 20BK from the left side of the paper, thereby forming an electrostatic latent image of black component.

Thereafter, the surface of the photosensitive drum 21 on which the electrostatic latent images of the respective colors are formed reaches positions facing the developing units 23Y, 23M, 23C, and 23BK, respectively. Then, the respective color toners are supplied onto the photosensitive drum 21 from the developing units 23Y, 23M, 23C, and 23BK, and the latent image on the photosensitive drum 21 is developed (development process).
Thereafter, the surface of the photosensitive drum 21 after the development process reaches a position facing the intermediate transfer belt 27. Here, the transfer bias roller 24 is installed at each facing position so as to contact the inner peripheral surface of the intermediate transfer belt 27. Then, at the position of the transfer bias roller 24, the images of the respective colors formed on the photosensitive drum 21 are sequentially superimposed and transferred onto the intermediate transfer belt 27 (first transfer step).

Then, the surface of the photosensitive drum 21 after the first transfer process reaches a position facing the cleaning unit 25. The untransferred toner remaining on the photosensitive drum 21 is collected by the cleaning unit 25 (this is a cleaning process).
Thereafter, the surface of the photosensitive drum 21 passes through a static elimination unit (not shown), and a series of image forming processes on the photosensitive drum 21 is completed.

On the other hand, the surface of the intermediate transfer belt 27 on which the images of the respective colors on the photosensitive drum 21 are transferred in an overlapping manner travels in the direction of the arrow in the drawing and reaches the position of the second transfer bias roller 28. Then, the full-color image on the intermediate transfer belt 27 is secondarily transferred onto the recording medium P at the position of the second transfer bias roller 28 (second transfer step).
Thereafter, the surface of the intermediate transfer belt 27 reaches the position of the intermediate transfer belt cleaning unit 29. Then, the untransferred toner on the intermediate transfer belt 27 is collected by the intermediate transfer belt cleaning unit 29, and a series of transfer processes on the intermediate transfer belt 27 is completed.

Here, the recording medium P at the position of the second transfer bias roller 28 is transported from the paper feeding unit 61 via the transport guide 63, the registration roller 64, and the like.
Specifically, the transfer paper P fed by the paper feed roller 62 from the paper feed unit 61 that stores the recording medium P passes through the conveyance guide 63 and is guided to the registration roller 64. The recording medium P that has reached the registration roller 64 is conveyed toward the position of the second transfer bias roller 28 in synchronization with the toner image on the intermediate transfer belt 27.

Thereafter, the recording medium P on which the full-color image is transferred is guided to the fixing unit 66 by the conveyance belt 30. In the fixing unit 66, the color image is fixed on the recording medium P at the nip between the heating roller 67 and the pressure roller 68.
Then, the recording medium P after the fixing process is discharged as an output image by the paper discharge roller 69 to the outside of the apparatus main body 1, and a series of image forming processes is completed.

Next, the image forming unit of the image forming apparatus will be described in detail with reference to FIGS.
FIG. 2 is a schematic cross-sectional view showing the vicinity of the image forming portion, and FIG. 3 is a cross-sectional view in the longitudinal direction (the direction perpendicular to the paper in FIG. 2) showing the developing portion.
Since the four image forming units installed in the apparatus main body 1 have substantially the same structure except that the color of the toner T used in the image forming process is different, alphabets (Y, M) of reference numerals in the process cartridge and the developing unit are used. , C, BK) are not shown.

  As shown in FIG. 2, the process cartridge 20 mainly contains a photosensitive drum 21 as an image carrier, a charging unit 22, and a cleaning unit 25 integrally in a case 26. The cleaning unit 25 is provided with a cleaning blade 25 a and a cleaning roller 25 b that are in contact with the photosensitive drum 21.

  The developing unit 23 mainly includes a developing roller 23a facing the photosensitive drum 21, a first conveying screw 23b facing the developing roller 23a, and a second conveying screw facing the first conveying screw 23b via a partition member 23e. 23c and a doctor blade 23d facing the developing roller 23a.

  Further, the developing unit 23 is provided with a first developer containing portion 23g and a second developer containing portion 23h separated by a partition member 23e. Referring to FIG. 3, the first developer accommodating portion 23g and the second developer accommodating portion 23h communicate with each other at both ends in the longitudinal direction (the range in which the partition member 23e is not interposed), and the developer circulation path. Is forming. A developing roller 23a, a first conveying screw 23b, and a doctor blade 23d are disposed in the first developer accommodating portion 23g. A second transport screw 23c and a magnetic sensor 40 are disposed in the second developer accommodating portion 23h.

  Referring to FIG. 3, the developing roller 23a includes a magnet 23a1 fixed inside and forming a magnetic pole on the roller peripheral surface, and a sleeve 23a2 made of a nonmagnetic material and rotating around the magnet 23a1. . A plurality of magnetic poles (main pole, transport pole, pumping pole, agent cutting pole, etc.) are formed on the developing roller 23a (sleeve 23a2) by the magnet 23a1.

  The developing roller 23a (sleeve 23a2) is connected to a drive motor (not shown) installed in the apparatus main body 1 and is rotationally driven by the drive motor. Although not shown, the developing roller 23a, the first transport screw 23b, and the second transport screw 23c are drivingly connected by a gear train. Thereby, as the developing roller 23a is rotationally driven by the drive motor, the first transport screw 23b and the second transport screw 23c are also rotationally driven following the development roller 23a.

A two-component developer G composed of toner T and carrier C is accommodated in the developing unit 23.
The toner T in the first embodiment (the toner in the developer G and the toner in the toner cartridge 33) contains toner base particles and additives composed of a resin and a colorant.
In addition, the toner T according to the first exemplary embodiment is synthesized by a polymerization reaction such as emulsion polymerization or suspension polymerization using a monomer, or by a method in which the resin itself is melted and sprayed to form fine particles. Alternatively, it can be produced by a method in which an additive is mixed and adhered to a base particle obtained by dispersing in water or the like to a predetermined particle size using a Henschel mixer or the like.

  As the resin contained in the toner T, styrene such as polystyrene, polychlorostyrene, polyvinyltoluene, and the like, and a substituted polymer thereof; styrene / p-chlorostyrene copolymer, styrene / propylene copolymer, styrene / vinyl Toluene copolymer, styrene / vinyl naphthalene copolymer, styrene / methyl acrylate copolymer, styrene / ethyl acrylate copolymer, styrene / butyl acrylate copolymer, styrene / octyl acrylate copolymer, styrene / Methyl methacrylate copolymer, styrene / ethyl methacrylate copolymer, styrene / butyl methacrylate copolymer, styrene / α-chloromethyl methacrylate copolymer, styrene / acrylonitrile copolymer, styrene / vinyl methyl ether Copolymer, styrene / vinyl ethyl Ether copolymer, styrene / vinyl methyl ketone copolymer, styrene / butadiene copolymer, styrene / isoprene copolymer, styrene / acrylonitrile / indene copolymer, styrene / maleic acid copolymer, styrene / maleic acid ester Styrene copolymers such as copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyvinyl butyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, A phenol resin, an aliphatic or alicyclic hydrocarbon resin, an aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like can be used alone or in combination of two or more.

  As the black colorant used for the toner T, carbon black, aniline black, furnace black, lamp black, and the like are used. Examples of cyan colorants include phthalocyanine blue, methyllene blue, Victoria blue, methyl violet, aniline blue, and ultramarine blue. As the magenta colorant, rhodamine 6G lake, dimethylquinacridone, watching red, rose bengal, rhodamine B, alizarin lake and the like are used. As the yellow colorant, chrome yellow, benzidine yellow, hansa yellow, naphthol yellow, molybdenum orange, quinoline yellow, tartrazine and the like are used.

  These toners T can contain a small amount of a charge imparting agent (for example, a dye or pigment, a polarity control agent, etc.) in order to impart the charge efficiently. As the polarity control agent, metal complex salts of monoazo dyes, nitrohumic acid and salts thereof, salicylic acid, naphthoic acid, metal complexes of dicarboxylic acid such as Co, Cr or Fe, organic dyes, quaternary ammonium salts and the like can be used.

  Examples of inorganic fine particles used as additives include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, iron oxide, copper oxide, zinc oxide, tin oxide, silica sand, clay, Mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, pengala, antimony trioxide, magnesium oxide, zirconium oxide, parium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride, and the like can be used. Among these, when two types of silica and titanium oxide are used, the effect of suppressing the burying of the additive in the toner and the effect of stabilizing the charging of the toner are particularly exhibited.

Further, the carrier C (the carrier C in the two-component developer G and the carrier C in the carrier cartridge 48) in the first embodiment is one in which a coating layer is formed on magnetic core particles. is there.
As the core particles of the carrier C, ferromagnetic metals such as iron, cobalt and nickel, alloys such as magnetite, hematite and ferrite, or compounds thereof are used.

  Examples of the resin for forming the coating layer of the carrier C include polyolefin resins such as polyethylene, polypropylene, chlorinated polyethylene, and chlorosulfonated polyethylene; polyvinyl and polyvinylidene resins such as polystyrene, acrylic resin (eg, polymethyl methacrylate), Polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether and polyvinyl ketone; vinyl chloride / vinyl acetate copolymer; styrene / acrylic acid copolymer; straight silicone resin composed of organosiloxane bond Or modified products thereof (for example, modified products by alkyd resin, polyester, epoxy resin, polyurethane, etc.); fluorine resin, For example, polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene; polyamide; polyester such as polyethylene terephthalate; polyurethane; polycarbonate; amino resin such as urea / formaldehyde resin; it can. Among these resins, acrylic resin, silicone resin or a modified product thereof, and fluorine resin are preferable from the viewpoint of preventing toner spent (particularly silicone resin or modified product thereof is preferable). As a method for forming the coating layer, a method in which a resin is applied to the surface of the carrier core particles by a spraying method, a dipping method or the like is used.

  In addition, a fine powder can be added to the coating layer to the carrier C in order to adjust the carrier resistance. The fine powder dispersed in the coating layer preferably has a particle size of about 0.01 to 5.0 μm. Moreover, it is preferable that 2-30 weight part (especially 5-20 weight part) is added with respect to 100 weight part of coating resin. As the fine powder, metal oxides such as silica, alumina and titania, and pigments such as carbon black can be used.

The above-described image forming process will be described in more detail with a focus on the developing process.
The developing roller 23a rotates in the direction of the arrow in FIG. As shown in FIG. 3, the developer G in the developing unit 23 is generated by the rotation of the first conveying screw 23 b and the second conveying screw 23 c arranged so as to interpose the partition member 23 e therebetween in the arrow direction. The toner T (new toner) supplied from the supply unit 32 through the developer supply port 23f is circulated in the longitudinal direction while being agitated and mixed (circulation in the direction of the broken line arrow in FIG. 3). The first transport screw 23b transports the developer G to the left side in FIG. 3, and the second transport screw 23c transports the developer G to the right side in FIG. 3 (in a direction opposite to the transport direction of the first transport screw 23b). Is transported to.

  Then, the toner T that is frictionally charged and adsorbed on the carrier C is carried on the developing roller 23 a together with the carrier C. The developer G carried on the developing roller 23a then reaches the position of the doctor blade 23d. The developer G on the developing roller 23a is adjusted to an appropriate amount at the position of the doctor blade 23d, and then reaches a position facing the photosensitive drum 21 (developing area).

  Thereafter, in the development area, the toner T in the developer G adheres to the electrostatic latent image formed on the surface of the photosensitive drum 21. Specifically, the toner T is latently exposed by the electric field formed by the potential difference (development potential) between the latent image potential (exposure potential) of the image area irradiated with the laser light L and the development bias applied to the development roller 23a. Adhere to the image.

  Thereafter, most of the toner T adhering to the photosensitive drum 21 in the developing process is transferred onto the intermediate transfer belt 27. The untransferred toner T remaining on the photosensitive drum 21 is collected in the cleaning unit 25 by the cleaning blade 25a and the cleaning roller 25b.

  Here, in the toner replenishing section 32 provided in the apparatus main body 1, a toner cartridge 33 containing a new toner T (any one of yellow, magenta, cyan, and black) is installed in a replaceable manner. (See FIG. 4). The new toner T accommodated in the toner cartridge 33 is guided to the developing unit 23 by the developer conveying device. The developer conveying device includes a tube 95 as a conveying tube, a screw pump 100 that generates a negative pressure in the tube 95, an air pump 90 that sends air into the toner cartridge 33, an air pump 91 as an air feeding means, and the like. Consists of. In addition, a carrier replenishing unit 47 is also connected to the developer conveying device in the first embodiment. The configuration and operation of the developer transport device will be described in detail later.

The toner T in the toner cartridge 33 is appropriately supplied into the developing unit 23 from the developer supply port 23f as the toner T in the developing unit 23 is consumed. The toner T in the developing unit 23 is consumed by a magnetic sensor 40 (toner density detecting means) installed below the second conveying screw 23c of the developing unit 23 or a photo sensor (not shown) facing the photosensitive drum 21. Is detected). Then, the developer replenishment unit 32 supplies the developer so that the detection result of the magnetic sensor 40 or the photo sensor becomes an output value corresponding to the target toner density (the ratio of the toner T in the developer G). Toner is replenished to the developing unit 23 through the opening 23f.
Adjustment of the amount of toner replenished to the developing unit 23 is performed by controlling the drive time of the screw pump 100.

Further, the developing unit 23 according to the first embodiment uses a trickle developing system.
The image forming apparatus according to the first embodiment includes a discharge unit 23k (see FIG. 2) that discharges a part of the developer G accommodated in the developing unit 23 to the outside of the developing unit 23, and the developing unit 23. A carrier replenishing unit 47 (which can be referred to FIG. 4) for newly replenishing the carrier C is provided.

  Specifically, a carrier replenishing unit 47 is connected to the developer conveying device in addition to the toner replenishing unit 32. A carrier cartridge 48 in which a new carrier C is accommodated is replaceably installed in the carrier replenishment section 47 (see FIG. 4). The new carrier C accommodated in the carrier cartridge 48 is guided to the developing unit 23 via the developer supply port 23f by the developer conveying device.

On the other hand, a developer discharge port 23k as discharge means is provided above the wall surface of the second developer accommodating portion 23h.
When the new carrier C is replenished from the carrier replenishing unit 47 into the developing unit 23 and the amount of developer in the developing unit 23 exceeds a predetermined amount, the excess developer G is discharged from the developer discharge port 23k. 23 is discharged outside. The developer G discharged from the developer discharge port 23k is conveyed to the developer recovery unit 44 via the developer recovery path 43.
In this way, as the new carrier C is replenished, the developer surface rises, and the developer G exceeding the height of the developer discharge port 23k is discharged out of the developing unit 23, so the agent in the developing unit 23 The surface (developer amount) is always kept constant.

That is, in the first embodiment, a new carrier (new developer) is appropriately supplied into the developing unit 23, and a part of the developer stored in the developing unit 23 is appropriately discharged out of the developing unit 23. Therefore, the amount of the developer stored in the developing unit 23 and the charging ability can be maintained by reducing the deteriorated carriers in the developing unit 23.
In the first embodiment, the overflow method is used as the discharging means for discharging the developer from the developing unit 23. However, an openable / closable shutter is provided at the developer discharge port 23k, and the developer is discharged by opening and closing the shutter. Can also be done.

Hereinafter, with reference to FIG. 4, the configuration and operation of the developer conveying device, which is characteristic of the first embodiment, will be described in detail.
Referring to FIG. 4, the developer conveying device includes a tube 95 as a conveying tube, a screw pump 100 that sends air in the tube 95 to generate negative pressure, and an air pump that sends air into the toner cartridge 33. 90 (second air supply means), an air pump 91 as an air supply means, and the like.

Here, the screw pump 100 according to the first embodiment is a suction pump including a rotor 101 and a stator 102, and generates a suction force at the suction port 103 by operating the rotor 101 (from the inside of the tube 95). Air is sent out to generate negative pressure.)
The main part of the screw pump is composed of a stator 102 and a rotor 101. The stator 102 is a female threaded member made of an elastic material such as rubber, and a double pitch spiral groove is formed therein. The rotor 101 is a male screw-shaped member made of metal, resin, or the like, and is rotatably inserted into the stator 102. The rotor 101 is connected to the drive shaft 104 via a spring pin, and is driven to rotate when the drive shaft 104 is rotated. Here, since the rotational motion by the drive shaft 104 is eccentric motion, the screw pump is also referred to as a uniaxial eccentric screw pump. As the rotor 101 rotates, a suction pressure is generated at the suction port 103, and the developer sucked from the suction port 103 is discharged to the discharge unit 105. The developer discharged to the discharge unit 105 is replenished into the developing unit 23 through the developer supply port 23f after the transport pipe 106 is dropped by its own weight.

The tube 95 as a transport tube is made of a material excellent in flexibility and toner resistance, and has an inner diameter of 2 to 8 mm. As the material of the tube 95, rubber materials such as polyurethane, nitrile, EPDM, silicon, and elastomer resin can be used.
By using such a flexible tube 95 and air conveyance of the carrier and the toner, the degree of freedom in the layout of the developer conveyance path is increased and the image forming apparatus is downsized. Since the developer conveying device in the first embodiment transfers the carrier and the toner by generating pressure in the tube 95 by the screw pump 100, the carrier cartridge 48 and the toner cartridge 33 are removed from the developing unit 23. It can also be arranged at a lower position.

One end of the tube 95 serving as a transport pipe is connected to the suction port 103 of the screw pump 100, and the other end is connected to the toner cartridge (toner accommodating portion) 33 via the nozzle 80.
A toner cartridge 33 as a toner storage unit is detachably installed in the nozzle 80. Then, the toner T in the toner cartridge 33 is transferred into the tube 95 via the toner discharge port 81 provided at the tip of the nozzle 80.

  An air pump 90 (second air supply means) is connected to the nozzle 80 via a porous tube 82 as a second porous member. Specifically, an air pump 90 is connected to the porous tube 82 of the nozzle 51 via a tube 93. The porous tube 82 is made of a porous material such as porous sintered glass. As the porous material, pores smaller than the average volume particle diameter of the toner T, for example, glass, metal or resin sintered porous plates or meshes having an average pore diameter of about 10 μm can be used.

When air is supplied from the air pump 90 into the nozzle 80, the gas is sent into the toner cartridge 33 through the toner discharge port 81, and the toner transportability in the nozzle 80 and in the vicinity of the toner discharge port 81 is improved. Will be enhanced.
Specifically, the air fed into the toner cartridge 33 through the porous tube 82 branches into many directions after entering the innumerable fine holes existing in the porous tube 82. Then, the air sent from the porous tube 82 through the infinite number of fine holes is mixed with the toner in the vicinity of the toner discharge port 81 in the state of infinitely branched bubbles. The mixture of toner and air formed in this way has a low bulk density and very high fluidity, and therefore has a transportability (toner discharge property) of the toner T discharged from the toner discharge port 81. Will improve.

Here, the toner cartridge 33 is a bottle-shaped (or bag-shaped) container made of a resin material. A cap member 33b to which the nozzle 80 is detachably attached is welded (or bonded) to the tip of the toner cartridge 33. Further, the base member 33b is provided with a seal member 33a made of polyurethane foam, rubber or the like. The nozzle 80 is inserted and removed while being in close contact with the seal member 33a, so that the leakage of the toner T from the toner cartridge 33 is suppressed.
Further, an opening is formed in the upper surface of the toner cartridge 33, and a filter 33c is covered over the opening. Thereby, even if air is sent into the toner cartridge 33 through the porous tube 82 by the air pump 90 as the second air supply means, the toner leakage from the toner cartridge 33 to the outside is suppressed and the toner is prevented. It is possible to prevent the internal pressure in the cartridge 33 from increasing. In addition, as the filter 33c, "Gore-Tex (registered trademark)" (manufactured by Japan Gore-Tex) or the like, which is a continuous porous structure made of a fluororesin, can be used.

In addition, a carrier cartridge (carrier accommodating portion) 48 is connected to the path of the tube 95 serving as a conveyance tube via a carrier feeder 70 and a nozzle 75.
A carrier discharge port 76 is provided at the tip of the nozzle 75, and the carrier C in the carrier cartridge 48 falls by its own weight into the nozzle 75 through the carrier discharge port 76. The carrier that has fallen into the nozzle 75 is held in the hole 72 provided in the rotating portion 71 of the carrier feeder 70. The rotating unit 71 is rotationally driven in the direction of the arrow by a motor (not shown). As a result, the carrier held in the hole 72 falls by its own weight into the tube 95 (the position where the porous tube 92c is installed). Thus, a certain amount of carrier is supplied into the tube 95 by the carrier feeder 70 functioning as a carrier supply port. The carrier is transported in the tube 95 together with air and toner T by the negative pressure generated by the screw pump 100.

  The carrier feeder 70 functioning as a carrier replenishing port is a tube when an air pump 91 as an air supply means described later is operating (when air is being fed into the tube 95). 95 is controlled so as not to replenish the carrier into 95 (the carrier replenishment port is closed). In other words, the air supply operation into the tube 95 by the air pump 91 and the carrier supply operation from the carrier supply unit 47 are not performed at the same time. This prevents air from being fed into the carrier cartridge 48 by the air feeding operation into the tube 95 by the air pump 91 and preventing the carrier replenishment (self-weight drop) from the carrier feeder 70 from being hindered. Because.

  Here, the carrier cartridge 48 is a bottle-shaped (or bag-shaped) container made of a resin material. A cap member 48b to which the nozzle 75 is detachably attached is welded (or bonded) to the tip of the carrier cartridge 48. Further, the base member 48b is provided with a seal member 48a made of foamed polyurethane, rubber or the like. The nozzle 75 is inserted and removed while being in close contact with the seal member 48a, so that leakage of the carrier C from the carrier cartridge 48 is suppressed.

Here, as a characteristic configuration of the first embodiment, porous tubes 92a to 92d as a plurality of porous members are installed in a path of a tube 95 as a transport tube. And the air pump 91 as an air supply means is connected to those porous pipes 92a-92d via the tubes 98 and 98a-98d.
The tubes 98, 98a to 98d connected to the air pump 91 serving as the air feeding means can be formed of the same material as the tube 95 serving as the transport pipe. And the air sent out from the air pump 91 is sent to each porous pipe | tube 92a-92d via each tube 98a-98d as a branch pipe from the tube 98 as a main pipe.

  The porous tubes 92a to 92d as the porous members are made of a fine porous material that allows air to pass therethrough, and the opening ratio is 5 to 40% (preferably 10 to 20%). The average opening diameter is 0.3 to 20 μm (preferably 5 to 15 μm), and the average pore diameter of the hole is 0.1 to 5 times the volume average particle diameter of the toner T. It is formed so as to have a size of (preferably 0.5 to 3 times). Examples of the porous material include porous resin materials such as glass, a sintered body of resin particles, a photo-etched resin, a thermally perforated resin; a metal sintered body, and a perforated metal plate By heating the copper plate prepared by depositing metallic copper around the surrounding material, net laminate, and easily fusible metal yarn bundle by an electrochemical method and through which the easily fusible metal yarn bundle is implanted, A metal material having a selective melt trace hole having a trace hole part from which the easily meltable metal yarn part has been selectively removed can be used.

The developer 95 is prevented from leaking out from the tube 95 by dividing the plurality of portions into the path of the tube 95 (conveyance tube) through the plurality of porous tubes 92 a to 92 d configured as described above and feeding air. However, the fluidity of the developer throughout the tube 95 can be improved.
Specifically, the air fed into the tube 95 through the porous tubes 92a to 92d branches in many directions after entering the innumerable fine holes existing in the porous tubes 92a to 92d. The gas sent from the porous tubes 92a to 92d through the infinite number of fine holes is uniformly stirred and mixed with the toner and the carrier in the tube 95 in the state of infinitely branched bubbles. To disperse. Since the toner and the carrier and carrier mixture uniformly dispersed in this way have a low bulk density and a very high fluidity, the developer transportability over the entire area of the tube 95 is improved.

  Specifically, as shown in FIG. 5, even if the tube 95 is on an inclined path against the gravity (developer is conveyed in the direction of the arrow), the carrier C is deposited as shown in FIG. The carrier C is uniformly dispersed in the tube 95 as shown in FIG.

  In the first embodiment, among the plurality of porous tubes 92a to 92d installed in the tube 95, one porous tube 92c is disposed in the vicinity of the carrier supply port (carrier feeder 70). Thus, by operating the air pump 91, the toner and the carrier conveyed in the tube 95 can be efficiently dispersed and mixed without depositing the carrier at the bottom of the tube 95 just below the carrier supply port.

The developer conveying device configured as described above operates as follows when the carrier is replenished.
When carrier replenishment from the carrier replenishing unit 47 to the developing unit 23 is performed, first, the rotation of the rotating unit 71 of the carrier feeder 70 is driven by an electric signal from the control unit in a state where the air pump 91 as an air supply means is stopped. Is started, and a desired amount of carrier is supplied into the tube 95. Thereafter, the air pump 91 as an air supply means is operated. That is, air is sent into the tube 95 by the air pump 91 via the plurality of porous tubes 92a to 92d. At this time, since the operation of the screw pump 100 is stopped, the sealing performance by the stator 102 and the rotor 101 is maintained. Therefore, the stirring efficiency between the toner and the carrier in the tube 95 is further improved. The air pump 91 supplies air into the tube 95 not only by dispersing and mixing the toner and carrier newly supplied into the tube 95 but also by dispersing and mixing the toner and carrier remaining in the tube 95. To do.

  Further, at this time, air is fed into the toner cartridge 33 and the nozzle 80 through the porous tube 82 by the air pump 90 as the second air feeding means. Thereby, the toner fluidity in the vicinity of the toner discharge port 81 and in the nozzle 80 is enhanced.

  Then, after the operation of the air pump 91 (dispersing and mixing the developer) is completed, the operation of the screw pump 100 is started and the developer is supplied to the developing unit 23. At this time, the developer passing between the stator 102 and the rotor 101 of the screw pump 100 has a stable toner / carrier ratio and a good dispersibility. As compared with the case where the ratio of the carrier having higher hardness is increased, the load applied to the stator 102 and the rotor 101 can be reduced. That is, wear between the stator 102 and the rotor 101 is reduced, and the durability of the screw pump 100 is also improved.

  As described above, according to the developer conveying device in the first embodiment, the gas is fed into the tube 95 via the porous tubes 92a to 92d arranged in the path of the tube 95. ing. As a result, the developers C and T can be efficiently and reliably conveyed without damaging the tubes 95 without damaging the developers C and T, with a relatively high layout freedom and with a relatively simple configuration. can do.

  In the first embodiment, the carrier cartridge 48 (carrier accommodating portion) that accommodates the carrier and the toner cartridge 33 (toner accommodating portion) that accommodates the toner are separated, and the development for conveying the carrier and the toner is performed. The present invention was applied to the agent transport device. On the other hand, a developer conveying device that conveys a two-component developer (toner and carrier) accommodated in a two-component developer accommodating portion, or a developer conveying device that conveys only a carrier accommodated in a carrier accommodating portion. The present invention can also be applied to this. Furthermore, the present invention can also be applied to a developer conveying device that conveys only the toner accommodated in the toner accommodating portion. In these cases, the developer (without the clogging of the conveying pipe) can be obtained by feeding the gas into the conveying pipe through one or more porous members disposed in the path of the conveying pipe. Toner and / or carrier) can be conveyed efficiently and reliably.

  In the first embodiment, the process cartridges 20Y, 20M, 20C, and 20BK are configured by integrating the photosensitive drum 21, the charging unit 22, and the cleaning unit 25, respectively. Further, each developing unit 23Y, 23M, 23C, 23BK is configured as a single unit. On the other hand, the developing units 23Y, 23M, 23C, and 23BK can be integrated with the process cartridges 20Y, 20M, 20C, and 20BK. That is, the process cartridge 20 can also be configured by the photosensitive drum 21, the charging unit 22, the developing unit 23, and the cleaning unit 25. Also in this case, the same effect as in the first embodiment is obtained. Furthermore, the maintainability of the image forming unit is improved.

Embodiment 2. FIG.
A second embodiment of the present invention will be described in detail with reference to FIG.
FIG. 6 is an overall configuration diagram illustrating the developer transport device according to the second embodiment. The developer conveying device according to the second exemplary embodiment is that the gas is fed into the toner accommodating portion 33 via the second porous member 112 installed on the inclined wall surface of the toner accommodating portion 33. It is different from that of Form 1.

As shown in FIG. 6, the developer conveying device in the second embodiment is similar to that in the first embodiment. An air pump 90 (second air supply means) is configured. In addition, a plurality of porous tubes (porous members) 92a to 92c are arranged in the tube 95 at substantially equal intervals. Then, air is sent into the tube 95 via the porous tubes 92 a to 92 c by the air pump 91, and the dispersibility of the developer in the tube 95 is improved.
In the second embodiment, the electromagnetic valve 111 is installed in the path of the tube 98 connected to the air pump 91, and the air supply operation to the tube 95 is controlled by opening / closing control of the electromagnetic valve 111. .

Here, in the second embodiment, the porous plate 112 as the second porous member is installed at a position buried in the toner accommodated in the toner cartridge 33 as the toner accommodating portion.
Specifically, the porous plate 112 is disposed on the inclined wall surface of the toner cartridge 33 in the vicinity of the toner discharge port 81 and surrounding the toner discharge port 81 in a state where the toner cartridge 33 is set. Here, the wall surface of the toner cartridge 33 surrounding the toner discharge port 81 is for efficiently sliding the toner in the toner cartridge 33 toward the toner discharge port 81, and has a funnel structure as its structure. A reverse truncated conical structure, a structure in which a cone, an elliptical cone, a triangular pyramid, or the like is reversed, a polygonal structure having a multi-sided wall having at least one surface as an inclined wall surface, and the like can be used.

Further, the porous plate 112 as the second porous member is connected to the air pump 90 as the second air supply means via the tube 93a, the electromagnetic valve 110, and the tube 93 in a state where the toner cartridge 33 is set. Configured to be connected. Furthermore, the air pump 90 is also connected to the porous tube 82 of the nozzle 80 via the tube 93, the electromagnetic valve 110, and the tube 93b.
The porous plate 112 and the porous tubes 82 and 92a to 92c are made of the same material as the porous tubes 82 and 92a to 92d in the first embodiment.

By sending air directly into the vicinity of the toner discharge port 81 through the porous plate 112 configured in this way, leakage of toner from the porous plate 112 is suppressed and the vicinity of the toner discharge port 81 is suppressed. The bulk density of the toner can be constantly reduced.
In other words, the air sent into the toner cartridge 33 through the porous plate 112 enters innumerable fine holes existing in the porous plate 112 and then branches in multiple directions. Then, the air sent from the porous plate 112 through the infinite number of fine holes is mixed with the toner in the vicinity of the toner discharge port 81 in the state of infinitely branched bubbles. Since the mixture of toner and air formed in this manner has a low bulk density and a very high fluidity, the transportability of the toner discharged from the toner discharge port 81 is improved.

  As described above, according to the developer transport device in the second embodiment, the gas is fed into the tube 95 via the porous tubes 92a to 92c arranged in the path of the tube 95. ing. As a result, the developers C and T can be efficiently and reliably conveyed without damaging the tubes 95 without damaging the developers C and T, with a relatively high layout freedom and with a relatively simple configuration. can do.

  It should be noted that the present invention is not limited to the above-described embodiments, and within the scope of the technical idea of the present invention, the embodiments can be modified as appropriate in addition to those suggested in the embodiments. Is clear. In addition, the number, position, shape, and the like of the constituent members are not limited to the above embodiments, and can be set to a number, position, shape, and the like that are suitable for carrying out the present invention.

1 is an overall configuration diagram illustrating an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is a schematic diagram illustrating the vicinity of an image forming unit in the image forming apparatus of FIG. 1. It is sectional drawing which looked at the image development part to the longitudinal direction. It is a whole block diagram which shows a developing agent conveyance apparatus. It is sectional drawing which shows the inclination path | route of a conveyance pipe. It is a whole block diagram which shows the developer conveying apparatus in Embodiment 2 of this invention.

Explanation of symbols

1 image forming apparatus body (apparatus body),
23, 23Y, 23M, 23C, 23BK Developing unit (developing device),
23f Developer supply port,
23k developer outlet (discharge means),
32, 32Y, 32M, 32C, 32BK toner supply unit,
33 toner cartridge (toner container),
43 developer collection path, 44 developer collection section,
47, 47Y, 47M, 47C, 47BK Carrier supply part,
48 carrier cartridge (carrier accommodating part),
70 Carrier feeder (carrier supply port),
75 nozzles, 76 carrier outlets,
80 nozzles, 81 toner outlet,
82 porous tube (second porous member),
90 Air pump (second air supply means),
91 Air pump (air supply means),
92a to 92d porous tube (porous member),
95 tubes (conveying tubes), 98 tubes,
100 Screw pump (pump),
112 porous plate (second porous member),
G Two-component developer, C carrier, T toner.

Claims (13)

A developer transport device for transporting a developer composed of toner and a carrier ,
A transport pipe through which the developer is transported together with a gas sent or delivered by a pump;
A porous member disposed singly or plurally so as to cover part or all of the outer periphery of the transport pipe in the path of the transport pipe;
An air feeding means for feeding gas into the transport pipe through the porous member;
Equipped with a,
The transport pipe communicates with a toner discharge port for discharging the toner stored in the toner storage unit and a carrier supply port for supplying the carrier stored in the carrier storage unit,
At least one of the porous members is disposed in the vicinity of the carrier supply port . The apparatus according to claim 1, further comprising a second air supply unit configured to supply gas into the toner storage portion via a second porous member disposed in the vicinity of the toner discharge port. The developer conveying device according to the description. The transport pipe includes a nozzle that is provided with the toner discharge port and is detachably installed in the toner storage unit,
The developer conveying apparatus according to claim 2, wherein the second air feeding unit is configured to feed gas into the nozzle via the second porous member. The developer conveying apparatus according to claim 2, wherein the second porous member is disposed at a position where the second porous member is buried in the toner accommodated in the toner accommodating portion. 5. The developer conveying device according to claim 1, wherein the carrier supply port is closed when the air supply unit is in operation. The developer transport device according to claim 1, wherein the pump is operated after the operation of the air supply unit is completed. The developer transport device according to claim 1, wherein the pump is a screw pump that delivers the developer together with gas from the transport pipe. 8. The conveying pipe accommodates toner and carrier and conveys the developer toward a developing unit that develops a latent image formed on an image carrier. The developer conveying device according to any one of the above. The developer conveying apparatus according to claim 8, wherein the developing unit includes a discharging unit that discharges a part of the toner and the carrier contained therein. The developer conveying apparatus according to claim 1, wherein the porous member is formed so that an opening ratio thereof is 5 to 40%. The developer conveying apparatus according to claim 1, wherein the porous member is formed so that an average opening diameter thereof is 0.3 to 20 μm. 12. The porous member according to claim 1, wherein the porous member is formed so that an average pore diameter of the pores is 0.1 to 5 times a volume average particle diameter of the toner. The developer conveying apparatus in any one. An image forming apparatus comprising the developer conveying device according to claim 1.

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