JP2007072347A - Developing device, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device designed such that supplied toner can be efficiently dispersed in a developer by a relatively simple configuration without increasing stress applied to the developer, and scattering of toner and image quality deterioration such as background dirtying are steadily restrained despite the elapse of time, and to provide a process cartridge and an image forming apparatus. <P>SOLUTION: The developing device includes: a second conveying member 23c that conveys a developer in a direction opposite to the conveying direction of a first conveying member 23b and forms a circulation passage for the developer together with the first conveying member 23b; and a supply port 23f disposed above the second conveying member 23c in order to supply toner into the developer circulating in the circulation passage. The second conveying means 23c conveys the developer such that the height of the developer passing through the lower part M of the supply port 23f is at least lower than the height of the developer passing downstream of the lower part M. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine, a printer, a facsimile, or a complex machine thereof, and a developing device and a process cartridge installed therein, and particularly includes a toner and a carrier The present invention relates to a developing device, a process cartridge, and an image forming apparatus using a two-component developer.

Conventionally, in an image forming apparatus using an electrophotographic system such as a copying machine, a printer, a facsimile, or a composite machine thereof, a two-component developer (added with an external additive or the like) composed of a non-magnetic toner and a magnetic carrier is added. In many cases, a developing device containing the same is used.
In such a two-component developing type developing device, a technique for supplying the developer to the developing roller while circulating the developer in the longitudinal direction of the developing device by a conveying screw is known for the purpose of downsizing the device. (For example, refer to Patent Document 1).

Specifically, the developing device includes a developing roller (developer carrying member), two transport screws (first transport member and second transport member), and the like.
Then, according to toner consumption in the developing device, toner is appropriately replenished into the device from a toner replenishing port (replenishing port) provided above the developing device. The replenished toner is mixed with the developer in the developing device while being circulated in the device in the longitudinal direction (the same direction as the rotation axis of the developing roller) by two transport screws. A part of the mixed developer is supplied to the developing roller by a conveying screw facing 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 developer adheres to the latent image on the photosensitive drum at a position facing the photosensitive drum (image carrier). .

  Since the developing device equipped with such a conveying screw actively circulates and conveys the developer in the longitudinal direction of the device, the deviation of the developer in the longitudinal direction is unlikely to occur. As a result, the toner replenishing port can be provided in a part of the longitudinal direction rather than being provided in the whole area in the longitudinal direction. Further, the conveying screw does not require much installation space in the short direction (the direction perpendicular to the longitudinal direction). Therefore, the developing device and the image forming apparatus can be reduced in size.

  On the other hand, since the specific gravity of the toner replenished from the toner replenishing port is smaller than that of the developer, the toner floats on the upper surface side of the developer circulating in the apparatus immediately after replenishment and enters the developer. There is a known problem that it is difficult to be dispersed (mixed) (for example, see Patent Document 1). Thus, if the replenishment toner (fresh toner) is not dispersed in the developer, the replenishment toner is not sufficiently charged due to friction with the carrier, and image quality deterioration such as background stain (fogging) and toner scattering occur. .

On the other hand, Japanese Patent Application Laid-Open No. H10-260260 discloses a technique for installing a magnetic field generating means downstream of the toner supply port in the circulation path and on the side or lower side of the second conveying screw.
That is, developer spikes are formed in the circulation path of the developer and the replenishment toner by the magnetic field generating means. Then, the replenishment toner is dispersed in the developer by colliding the replenishment toner with the spikes of the developer.

  Patent Document 2 and the like disclose a technique in which a plurality of projecting members are provided on a rotation shaft portion of a conveying member (developer stirring and conveying member) for the purpose of suppressing an insufficient charge amount of the developer and the like. .

JP 2000-89550 A JP 2000-19823 A

  The conventional developing device has a complicated configuration or an increased stress applied to the developer, and the replenishment toner cannot be efficiently dispersed in the developer.

In the technique of Patent Document 1 or the like, it is necessary to provide a magnetic field generating means in order to disperse the replenishment toner in the developer, and the developing device is complicated and expensive.
In addition, since the magnetic field generating means is installed on the side or lower side of the second conveying screw, it is necessary to considerably increase the strength of the magnetic field generated by the magnetic field generating means when trying to improve the dispersibility of the replenishing toner. It was. For this reason, there is a possibility that a strong developer ear is formed on the side or the lower side of the second conveying screw and the developer conveyance is stagnated. When the developer transport is stagnant, the amount of developer supplied from the first transport screw to the developing roller decreases, resulting in a decrease in density or density deviation of the output image, or a heavy load on the second transport screw. It will be.

  In addition, the technique disclosed in Patent Document 2 is to improve the dispersibility of the developer by preventing the charge amount from being insufficient by providing a plurality of projecting members separately from the screw portion on the rotating shaft portion of the conveying member. is there. However, providing the projecting member on the conveying member increases the stress applied to the developer (carrier). Therefore, the charging ability of the carrier is lowered relatively early, and the replenishment toner cannot be stably charged for a long time.

  The present invention has been made to solve the above-described problems, and can efficiently distribute replenishment toner in a developer with a relatively simple configuration and without increasing the stress applied to the developer. Therefore, it is an object of the present invention to provide a developing device, a process cartridge, and an image forming apparatus in which deterioration of image quality such as background stains and toner scattering are stably suppressed over time.

  A developing device according to a first aspect of the present invention is a developing device that contains a developer having toner and a carrier and that develops a latent image formed on the image carrier, and the image carrier. A developer carrying body that carries the developer, a first carrying member that faces the developer carrying body and carries the developer in the longitudinal direction, and the first member through the partition member. A second conveying member facing the one conveying member and conveying the developer in a direction opposite to the conveying direction of the first conveying member to form a circulation path of the developer together with the first conveying member; A replenishing port disposed above the second conveying member for replenishing toner into the developer that circulates in the circulation path, and the second conveying means has a position below the replenishing port. The height of the developer passing therethrough is small Kutomo is to convey the developer so as to be lower than the height of the developer that passes through the downstream side of the lower position.

  According to a second aspect of the present invention, there is provided the developing device according to the first aspect, wherein the height of the developer passing through the lower position of the replenishing port is the lower position. The developer is transported so as to be lower than the height of the developer passing through a position other than.

  According to a third aspect of the present invention, there is provided the developing device according to the first or second aspect, wherein the second conveying means is a conveying speed of the developer passing through a position below the replenishing port. The height of the developer at the lower position is lowered by speeding up the process.

  According to a fourth aspect of the present invention, in the developing device according to the third aspect, the second conveying means includes a shaft portion and a screw portion, and the shaft at a position below the supply port. The developer conveying speed at the lower position is increased by changing the screw angle formed by the screw portion and the screw portion.

  According to a fifth aspect of the present invention, in the developing device according to the fourth aspect, the second conveying means is configured such that the screw angle is not less than 40 degrees and less than 90 degrees. The screw angle at the lower position of the replenishing port is configured to be smaller than the screw angle at a position other than the lower position.

  According to a sixth aspect of the present invention, there is provided the developing device according to any one of the first to fifth aspects, wherein the second transporting unit occupies a small volume at a position below the replenishing port. By doing so, the height of the developer at the lower position is lowered.

  According to a seventh aspect of the present invention, in the developing device according to the sixth aspect, the second conveying means includes a shaft portion and a screw portion, and the shaft at a position below the supply port. The volume at the lower position is reduced by constituting the shaft diameter of the portion to be smaller.

  The developing device according to an eighth aspect of the present invention is the developing device according to any one of the first to seventh aspects, wherein the replenishing port is provided at the most upstream portion of the circulation path by the second conveying means. It is arranged above.

  According to a ninth aspect of the present invention, there is provided a developing device according to any one of the first to eighth aspects, wherein the replenishing device replenishes a carrier into the device, and is accommodated in the device. And a developer discharging means for discharging a part of the developer.

  According to a tenth aspect of the present invention, in the developing device according to the ninth aspect, the carrier replenishing means replenishes toner into the apparatus together with the carrier.

  A process cartridge according to an eleventh aspect of the present invention is a process cartridge that is detachably installed on the apparatus main body of the image forming apparatus, and the process cartridge according to any one of the first to tenth aspects. The developing device and the image carrier are integrated.

  An image forming apparatus according to a twelfth aspect of the present invention includes the developing device according to any one of the first to tenth aspects and the image carrier.

  In the present application, the “process cartridge” refers to a charging unit that charges the image carrier, a developing device (developing unit) that develops a latent image formed on the image carrier, and a cleaning on the image carrier. It is defined as a unit in which at least one of the cleaning units and the image carrier are integrated and configured to be detachable from the image forming apparatus main body.

  In the present invention, the second conveying means conveys the developer so that the height of the developer passing through the lower position of the replenishing port is lower than the height of the developer passing downstream of the lower position. is there. This makes it possible to disperse the replenishment toner efficiently in the developer with a relatively simple configuration without increasing the stress on the developer, resulting in image quality deterioration such as background stains and toner scattering. It is possible to provide a developing device, a process cartridge, and an image forming apparatus that are stably suppressed even over time.

  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.
The 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, 23C and 23BK are developing devices (developing units) for developing the electrostatic latent image formed on the photosensitive drum 21, and 24 is 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 devices 23Y and 23M. , 23C and 23BK, a toner replenishing unit for replenishing each color toner, 51 a document conveying unit for conveying the document D to the document reading unit 55, 55 for a document reading unit (scanner) for reading image information of the document D, and 61 for transferring A paper feed unit 66 for storing a recording medium P such as paper, and a fixing unit 66 for fixing an unfixed image on the recording medium P are shown.

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 when a four-color full-color image is formed 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 color separation light of RGB (red, green, blue) by the color sensor, and then converted into an electrical image signal. Further, the image processing unit (not shown) performs color conversion processing, color correction processing, spatial frequency correction processing, and the like based on the RGB color separation image signals, and performs yellow, magenta, cyan, and black processing. 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 directed from the writing unit 2 onto the photosensitive drum 21 (image carrier) of the corresponding process cartridge 20Y, 20M, 20C, 20BK, respectively. Be emitted.

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 devices 23Y, 23M, 23C, and 23BK, respectively. Then, the respective color toners are supplied from the developing devices 23Y, 23M, 23C, and 23BK onto the photosensitive drum 21, and the latent image on the photosensitive drum 21 is developed (this is a developing step).
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.
The operation of the image forming apparatus at the time of monochrome image formation or three-color image formation is different only in the number of image forming portions on which the image is formed, and the basic operation is the same as the above-described four-color full color image formation. It is the same as that.

Next, the image forming unit of the image forming apparatus will be described in detail with reference to FIGS.
FIG. 2 is a cross-sectional view showing the image forming unit, and FIG. 3 is a cross-sectional view in the longitudinal direction (vertical direction in FIG. 2) showing the developing device.
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. Therefore, the alphabet of reference numerals in the process cartridge, the developing device, and the toner replenishing unit. (Y, M, C, BK) is omitted for illustration.

  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. In the first embodiment, the outer diameter of the photosensitive drum 21 is 30 mm, and the linear velocity on the outer peripheral surface is set to 240 mm / second.

  The developing device 23 mainly includes a developing roller 23a as a developer carrying member facing the photosensitive drum 21, a first conveying screw 23b as a first conveying member facing the developing roller 23a, and a partition member 23e. A second conveying screw 23c as a second conveying member facing the first conveying screw 23b and a doctor blade 23d (developer regulating member) facing the developing roller 23a are configured.

  Further, the developing device 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. In the first developer accommodating portion 23g, a developing roller 23a, a first conveying screw 23b, a doctor blade 23d, and the like are disposed. A second transport screw 23c, a magnetic sensor 40, and the like 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.

In the first embodiment, the developing roller 23a has an outer diameter of 18 mm, a gap (developing gap) with the photosensitive drum 21 is 0.3 mm, and the linear velocity on the outer peripheral surface of the developing roller 23a is It is set to 408 mm / sec.
Furthermore, the 1st conveyance screw 23b and the 2nd conveyance screw 23c are mainly comprised by the axial part and the screw part (it is a single thread screw). As for the 1st conveyance screw 23b and the 2nd conveyance screw 23c, the axial diameter of the shaft part is 6 mm, the outer diameter of the screw part is 12 mm, and the rotation speed is set to 400 rpm.

In the developing device 23, a two-component developer G composed of toner T and carrier C is accommodated.
The toner T (the toner in the developer G and the toner in the toner replenishing unit 32) in the first embodiment contains toner base particles and additives made of a resin and a colorant. The particle size of the toner T is 5.5 μm.
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 in the developer G in the first embodiment is one in which a coating layer is formed on magnetic core particles. The particle size of the carrier C is 35 μm.
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 device 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. It circulates in the longitudinal direction while being agitated and mixed with the toner T (new toner) replenished from the replenishing part 32 through the replenishing port 23f (circulation in the direction of the broken arrow in FIG. 3). The first transport screw 23b (first transport member) transports the developer G to the left side in FIG. 3, and the second transport screw 23c (second transport member) transports the developer G to the right side in FIG. It is conveyed in the direction opposite to the conveying direction of the conveying screw 23b.

  In the first embodiment, the replenishing port 23f is the most upstream part (the left end in FIG. 3 and the first developer accommodating part 23g) of the developer circulation path (conveyance path) by the second conveyance screw 23c. In the vicinity of the position where the developer is transferred to the second developer accommodating portion 23h. Accordingly, it is possible to ensure the maximum time for the toner T after replenishment to be dispersed in the developer G before reaching the first developer accommodating portion 23g. Therefore, the tribocharging of the replenishment toner accompanying the dispersion in the developer is sufficiently performed, and image quality deterioration such as background contamination and toner scattering are suppressed.

  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, the toner replenishing unit 32 provided in the apparatus main body 1 is a toner replenishing path that guides the toner cartridge 33 configured to be replaceable and a new toner (supplementary toner) T discharged from the toner cartridge 33 to the developing device 23. 34. In addition, a new toner T (any of yellow, magenta, cyan, and black) is accommodated in the toner cartridge 33.

The toner T in the toner cartridge 33 is appropriately supplied into the developing device 23 from the supply port 23f as the toner T in the developing device 23 is consumed. The toner T in the developing device 23 is consumed by a magnetic sensor 40 (toner concentration detecting means) installed below the second conveying screw 23c of the developing device 23 or a photo sensor (not shown) facing the photosensitive drum 21. Is detected). Then, the toner supply unit 32 supplies the supply port 23f 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). Then, the toner is supplied to the developing device 23.
Although illustration is omitted, adjustment of the amount of toner replenished to the developing device 23 is performed by controlling the amount of rotation of the screw disposed in the toner replenishment path 34 by a pulse drive motor (toner transport motor). In addition to the screw mechanism described above, a powder pump mechanism can also be used as the conveying means in the toner supply path 34.

Hereinafter, a characteristic configuration and operation of the developing device 23 according to the first embodiment will be described.
Referring to FIG. 3, in the second transport screw 23c, the transport speed of the developer passing through the lower position M of the supply port 23f is higher than the transport speed of the developer passing through a position other than the lower position M. It is configured.
Specifically, the second transport screw 23c is configured such that the screw angle α2 at the lower position M of the supply port 23f is smaller than the screw angle α1 at other positions than the lower position M (α2 <α1). ). Further, both screw angles α1, α2 are configured to be 40 degrees or more and less than 90 degrees. Specifically, the screw angle α2 at the lower position M of the supply port 23f is 40 degrees, and the screw angle α1 at positions other than the lower position M is 72 degrees.
The “screw angle” is defined as an angle formed by the shaft portion (axial line) and the screw portion (periphery line) in the second conveying screw 23c in the conveying direction.

Here, the speed at which the developer is transported (developer transport speed) is mainly determined by the rotational speed of the transport screw (second transport screw 23c) and the screw angle α. That is, if the rotation speed is constant, the developer conveyance speed at that position can be varied by changing the screw angle α at the specific position.
FIG. 4 is a graph schematically showing the relationship between the screw angle α and the developer conveyance speed. As shown in FIG. 4, when the screw angle α is decreased, the developer conveyance speed is increased. However, when the screw angle α is equal to or smaller than a predetermined value (40 degrees in the first embodiment), the conveyance speed is decreased. . This is because when the screw angle α is equal to or smaller than a predetermined value, the force of stirring in the vertical direction exceeds the force of the conveying screw sending in the horizontal direction.

  Due to such characteristics of the conveying screw, in the first embodiment, the developer conveying speed at that position is increased by reducing the screw angle α2 at the lower position M of the supply port 23f within a range of 40 degrees or more. . As a result, the height (agent surface) of the developer at the lower position M of the supply port 23f is lower than the height (agent surface) of the developer at a position other than the lower position M (see FIG. 5). .

FIG. 5 is a cross-sectional view of the second developer accommodating portion 23h as viewed from the rear of the developing device 23 in the longitudinal direction.
Referring to FIG. 5, a developer step F is formed on the downstream side of the lower position M due to the difference in developer conveyance speed. As a result, even if the replenishment toner T1 replenished from the replenishing port 23f floats on the upper surface side of the recirculating developers T and C, the replenishment toner T1 subsequently collides with the stepped portion F on the downstream side of the lower position M and has its path Directed downward. Further, the replenishing toner T1 replenished from the replenishing port 23f is taken into the developer that is immediately recirculated by the second conveying screw 23c whose surface is lowered and a part of the screw portion is exposed. Thus, the replenishing toner T1 replenished from the replenishing port 23f is efficiently dispersed and mixed in the developers T and C in a short time, and sufficient frictional charging with the carrier C is performed. As a result, it is possible to reduce image quality deterioration such as background stains and toner scattering.

More specifically, when the agent surface at the lower position M is high (conventional configuration), the toner T1 replenished on the agent surface exerts a downward force by the screw portion (blade) of the second conveying screw 23c. Since the toner is less likely to be received, the replenishment toner T1 is less likely to sink into the developer. As a result, the replenishment toner T1 slides above the second transport screw 23c and is transported without being mixed with the developer.
On the other hand, in the first embodiment, since the surface of the lower position M is low, the replenishment toner T1 receives a large amount of downward force from the second transport screw 23c and enters the developer. It will easily sink. As a result, the mixing of the replenishment toner T1 and the developer is promoted. Further, if the developer surface of the developer contained in the developing unit 23 is lowered as a whole, the developer capacity is reduced. Therefore, the developer surface is partially lowered only in the lower position M. The configuration of the form 1 achieves both a reduction in the size of the developing unit and an increase in the developer capacity.

In the first embodiment, in order to form a difference in screw angle, the screw pitch N2 at the lower position M of the supply port 23f of the second transport screw 23c is larger than the screw pitch N1 at other positions than the lower position M. It is comprised so that it may become.
Further, the average developer conveyance speed by the two conveyance screws 23b and 23c is set to be equal so that the developer amount between the two developer accommodating portions 23g and 23h in the developing device is balanced.

Hereinafter, the relationship between the replenishment toner, the toner scattering, and the background stain will be described in detail.
The newly replenished toner from the replenishing port 32f is sufficiently dispersed in the developer and brought into contact with the carrier until it is pumped onto the developing roller 23a, and has a charge amount of a certain value or more opposite to the carrier. Need to be. When the replenishment toner is not sufficiently charged, the toner easily detaches from the carrier immediately after being pumped up by the developing roller 23a, which causes toner scattering and background contamination.

FIG. 6 shows the charge amount distribution of the toner in the developer. For the toner charge amount distribution measurement, a toner particle charge amount distribution measuring apparatus “E-Spart Analyzer” (manufactured by Hosokawa Micron) using a laser Doppler velocimeter was used. Since the toner used in Embodiment 1 is a negative polarity toner, the toner is sufficiently charged as it is on the minus side. Here, the weakly charged toner having a low charge amount is a toner of −1fc / 10 μm or more (the toner in the shaded area).
FIG. 7 is a graph showing the relationship between the ratio of the weakly charged toner and the toner scattering amount. In FIG. 7, the horizontal axis indicates the ratio of the weakly charged toner, and the vertical axis indicates the amount of toner scattering. The ratio of the weakly charged toner is the percentage of the number of weakly charged toners determined in FIG. 6 as a ratio to the total number. FIG. 7 shows that the amount of toner scattering increases as the amount of weakly charged toner in the developer increases.

  FIG. 8 is a graph showing the relationship between the driving time of the developing device after toner replenishment and the ratio of weakly charged toner (charge amount distribution) in the developer carried on the developing roller. From FIG. 8, the replenished toner replenished from the replenishing port 23f moves along the circulation path and reaches the developing roller 23a about 8 seconds later, and at the same time, the amount of weakly charged toner peaks (dotted circle in FIG. 8). It is understood that Therefore, if the value of this peak is suppressed within the toner scattering allowable range in FIG. 7 (the range of the arrow marked “OK” in FIG. 7), the occurrence of toner scattering associated with toner replenishment can be reduced. Is possible.

In the first embodiment, as described above, the height of the developer at the lower position M of the supply port 23f is at least lower than the height of the developer at the downstream side of the lower position M (step F). In other words, the dispersibility of the replenishing toner is enhanced and sufficient frictional charging with the carrier is performed. That is, since the peak of the weakly charged toner rate in FIG. 8 becomes small, the amount of toner scattering caused by toner replenishment can be surely reduced.
Since the background contamination increases with an increase in the weakly charged toner rate, as in the case of toner scattering, the amount of generation of background contamination due to toner replenishment is reliably reduced by the configuration of the first embodiment. be able to.

  As described above, according to the configuration of the first embodiment, the height of the developer G passing through the lower position M of the supply port 23f is higher than the height of the developer G passing through the downstream side of the lower position M. The second conveying screw 23c conveys the developer G so as to be lower. This makes it possible to disperse the replenishing toner efficiently in the developer with a relatively simple configuration without increasing the stress applied to the developer, and to prevent image deterioration such as background stains and toner scattering. Stable deterrence is possible even over time.

  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 device 23Y, 23M, 23C, 23BK is configured as a single unit. On the other hand, the developing devices 23Y, 23M, 23C, and 23BK can be integrated with the process cartridges 20Y, 20M, 20C, and 20BK. In other words, the process cartridge 20 can be configured by the photosensitive drum 21, the charging unit 22, the developing device 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.

In the first embodiment, the developer transport speed at the lower position M is increased by increasing the transport speed of the developer passing through the lower position M of the supply port 23f in the transport path formed by the second transport screw 23c. The dispersibility of the replenishing toner was increased by reducing the thickness.
On the other hand, in the transport path formed by the second transport screw 23c, the volume occupied by the second transport screw 23c at the position M below the supply port 23f can be reduced. For example, by configuring the shaft diameter of the second conveyance screw 23c to be small at the lower position M, the occupied volume of the second conveyance screw 23c at the lower position M is reduced. Also in this case, since the height of the developer at the lower position M can be lowered, the same effect as in the first embodiment can be obtained.

Embodiment 2. FIG.
A second embodiment of the present invention will be described in detail with reference to FIG.
FIG. 9 is a cross-sectional view showing the developing device and its vicinity in the second embodiment, and corresponds to FIG. 2 in the first embodiment. The image forming apparatus according to the second embodiment includes a carrier supply unit 47 that newly supplies a carrier into the developing device 23 and a developer discharge unit 23k that discharges a part of the developer stored in the developing device 23. The installed point is different from that of the first embodiment.

The developing device 23 in the second embodiment uses a trickle developing system.
As shown in FIG. 9, the image forming apparatus according to the second embodiment includes a developer discharging unit 23k that discharges a part of the developer G stored in the developing device 23 to the outside of the developing device 23, and the developing device. 23, a carrier replenishing unit 47 as a carrier replenishing means for newly replenishing the carrier C is provided.

Specifically, a carrier replenishing portion 47 as a carrier replenishing unit is provided above the second developer accommodating portion 23 h separately from the toner replenishing portion 32. The carrier supply unit 47 includes a carrier cartridge 48 configured to be replaceable, and a carrier supply path 49 that guides the new carrier C discharged from the carrier cartridge 48 to the developing device 23 through the supply port 23f. . A new carrier C is accommodated in the carrier cartridge 48. Then, the carrier is appropriately supplied from the carrier supply unit 47 into the developing device 23 at a predetermined timing.
Although illustration is omitted, adjustment of the carrier replenishment amount to be replenished to the developing device 23 is performed by controlling the operation time or the operation frequency of the screw disposed in the carrier replenishment path 49 with a pulse drive motor. In addition to the screw mechanism described above, a powder pump mechanism can also be used as the conveying means in the carrier supply path 49.

On the other hand, a developer discharge port 23k as a developer discharge means is provided in the vicinity of the upper end of the wall surface of the second developer storage portion 23h and downstream of the supply port 23f.
When the new carrier C is supplied from the carrier supply unit 47 into the developing device 23 and the amount of developer in the developing device 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 (height) rises, and the developer G exceeding the height of the developer discharge port 23k is discharged out of the developing device 23. The amount of developer in the developing device 23 is always kept constant.
In the second embodiment, the overflow method is used as the developer discharging means for discharging the developer from the developing device 23. However, the developer discharge port 23k is provided with an openable / closable shutter, and the developer is opened and closed by opening and closing the shutter. Can also be discharged.

Also in the second embodiment, as in the first embodiment, the transport speed of the developer passing through the lower position M of the supply port 23f is increased in the transport path formed by the second transport screw 23c. Yes. As a result, the dispersibility of the replenishing toner is enhanced, and the amount of weakly charged toner generated can be reduced.
Further, since the replenishment toner has improved dispersibility (because it is difficult to float on the upper surface of the developer), the problem that the toner immediately after replenishment overflows and is discharged from the developer discharge port 23k is suppressed.
Further, in the second embodiment, the trickle developing method is used, and the deteriorated carrier whose charging ability is reduced is appropriately discharged from the developing device 23. Therefore, the generation of weakly charged toner due to the deterioration of the carrier with time is generated. The amount can be reduced.

  As described above, according to the configuration of the second embodiment, as in the first embodiment, the replenishment toner is contained in the developer with a relatively simple configuration and without increasing the stress applied to the developer. Can be efficiently dispersed, and deterioration of image quality such as background stains and toner scattering can be stably suppressed over time.

  In the second embodiment, the new carrier C is supplied from the carrier supply unit 47. However, a new developer G may be supplied from the carrier supply unit 47. Also in this case, the same effects as those of the second embodiment are obtained.

Example.
With reference to FIGS. 10 and 11, experiments (Examples and Comparative Examples) for confirming the effects of the above-described embodiments will be described.
FIG. 10 is a schematic cross-sectional view showing the configuration of the experimental machine, and is a view of the second developer accommodating portion 23h as seen from the rear of the developing device 23 in the longitudinal direction. FIG. 11 is a table showing the experimental results.

FIG. 10A is a diagram illustrating an experimental machine according to a comparative example. In the comparative example, the one in which the screw angle of the second conveying screw 23c in the developing device of Embodiment 1 is uniformized to 72 degrees is used (the configuration of the conventional developing device).
FIG. 10B is a diagram illustrating an experimental machine according to the first embodiment. In Example 1, the screw angle α2 (the screw angle at the lower position M) of the second conveying screw 23c in the developing device of Embodiment 1 is set to 50 degrees, and the position of the supply port 23f is set from the most upstream part. Is also used on the downstream side.
FIG. 10C is a diagram illustrating an experimental machine according to the second embodiment. In the second embodiment, the shaft diameter D2 of the shaft portion at the lower position M of the second conveying screw 23c in the developing device of the first embodiment is 4 mm. The shaft diameter D1 of the shaft portion at a position other than the lower position M is 6 mm.
FIG. 10D is a diagram illustrating an experimental machine according to the third embodiment. In the third embodiment, the screw angle α2 (the screw angle at the lower position M) of the second transport screw 23c in the developing device of the second embodiment is set to 40 degrees, and the position of the supply port 23f is provided at the most upstream portion. (The only difference is the shaft diameter D2 with respect to the developing device of the first embodiment).
Although illustration is omitted, in Example 4, the developing device of Example 3 provided with a carrier replenishing unit and a developer discharging unit (shaft diameter D2 with respect to the developing device of Embodiment 2) is used. Only different.).

  FIG. 11 shows the results of measurement of toner charge amount distribution before and after the continuous output of 100,000 images with an image area ratio of 5% using the experimental devices of the comparative example and examples 1 to 4, respectively. It is a thing. Specifically, the peak value of the weakly charged toner amount before and after toner replenishment before the running test (initial) (the value at the dotted circle in FIG. 8) and the weakly charged toner before and after toner replenishment after the running test (timed). The peak value of the toner amount was measured. It is known that toner scattering does not occur when the amount of weakly charged toner is 15% by number or less.

From FIG. 11, it can be seen that the amount of weakly charged toner is reduced to a level at which toner scattering does not occur in Examples 1 to 4, compared to the comparative example in which toner scattering occurs. In addition, it can be seen that the amount of weakly charged toner is gradually reduced in Examples 1 to 4. These results are due to the reasons described in the respective embodiments.
When the developer height at the lower position M of the supply port 23f in each experimental machine was visually confirmed, the developer height at the lower position M in the comparative example was the same as that at other positions. In Example 1, the developer height at the lower position M was lower than those at other positions, and in Example 2, the developer height at the lower position M was even lower than that in Example 1. .

  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 cross-sectional view illustrating an image forming unit in the image forming apparatus of FIG. 1. It is sectional drawing which looked at the developing device to the longitudinal direction. It is a graph which shows the relationship between the screw angle in a 2nd conveyance member, and a developer conveyance speed. FIG. 6 is a cross-sectional view of a second developer accommodating portion as viewed from the rear of the developing device in the longitudinal direction. FIG. 6 is a distribution diagram showing a charge amount distribution of toner in a developer. 6 is a graph showing a relationship between a ratio of weakly charged toner and a toner scattering amount. 6 is a graph showing a relationship between a driving time after toner replenishment and a ratio of weakly charged toner in a developer carried on a developer carrying member. It is sectional drawing which shows the developing device in Embodiment 2 of this invention. It is a schematic sectional drawing which shows the structure of the 2nd developer accommodating part in an experimental machine. It is a table | surface figure which shows an experimental result.

Explanation of symbols

1 image forming apparatus body (apparatus body),
20, 20Y, 20M, 20C, 20BK Process cartridge,
21 photosensitive drum (image carrier), 22 charging unit,
23, 23Y, 23M, 23C, 23BK Developing device (developing unit),
23a Development roller (developer carrier),
23b 1st conveyance screw (1st conveyance member),
23c 2nd conveyance screw (2nd conveyance member),
23d doctor blade, 23f supply port (toner supply port),
23g first developer accommodating portion, 23h second developer accommodating portion,
23k developer discharge port (developer discharge means),
32, 32Y, 32M, 32C, 32BK toner supply unit,
33 toner cartridge, 34 toner supply path,
43 developer collection path, 44 developer collection section,
47 Carrier supply part (carrier supply means),
48 carrier cartridge, 49 carrier supply route,
G Two-component developer (developer), C carrier, T toner.

Claims (12)

A developing device for containing a developer having toner and a carrier and developing a latent image formed on an image carrier,
A developer carrying body facing the image carrying body and carrying the developer;
A first conveying member facing the developer carrying member and conveying the developer in the longitudinal direction;
Opposite the first conveying member via a partition member, convey the developer in a direction opposite to the conveying direction of the first conveying member, and form a circulation path for the developer together with the first conveying member A second conveying member that
A replenishing port disposed above the second conveying member for replenishing toner into the developer circulating in the circulation path,
The second transport unit transports the developer so that the height of the developer passing through a position below the replenishing port is at least lower than the height of the developer passing through the downstream side of the lower position. A developing device. The second transport unit transports the developer such that a height of the developer passing through a position below the replenishing port is lower than a height of the developer passing through a position other than the lower position. The developing device according to claim 1. 2. The second transport unit reduces the height of the developer at the lower position by increasing the transport speed of the developer passing through the lower position of the replenishing port. 2. The developing device according to 2. The second conveying means includes a shaft portion and a screw portion, and changes the screw angle formed by the shaft portion and the screw portion at a position below the replenishing port, thereby conveying the developer at the lower position. The developing device according to claim 3, wherein the developing device is accelerated. The second conveying means is configured so that the screw angle is not less than 40 degrees and less than 90 degrees, and the screw angle at a position below the supply port is smaller than the screw angle at a position other than the lower position. The developing device according to claim 4, wherein the developing device is configured as follows. The said 2nd conveyance means makes the height of the said developer in the said lower position low by making small the volume occupied in the lower position of the said supply port, The any one of Claims 1-5 characterized by the above-mentioned. The developing device according to 1. The second conveying means includes a shaft portion and a screw portion, and is configured such that the shaft diameter of the shaft portion at a lower position of the replenishing port is reduced to reduce the volume at the lower position. The developing device according to claim 6, wherein: The developing device according to claim 1, wherein the replenishing port is disposed above the most upstream portion of the circulation path by the second transport unit. A carrier replenishing means for replenishing a new carrier in the apparatus;
Developer discharging means for discharging a part of the developer accommodated in the apparatus;
The developing device according to claim 1, further comprising: The developing device according to claim 9, wherein the carrier replenishing unit replenishes toner into the apparatus together with the carrier. A process cartridge that is detachably installed on the main body of the image forming apparatus,
11. A process cartridge in which the developing device according to claim 1 and the image carrier are integrated. An image forming apparatus comprising the developing device according to claim 1 and the image carrier.

Images