JP2011033748A - Developing device and image forming apparatus including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of simultaneously eliminating toner scattering due to charging failure and sweeping unevenness by a magnetic brush with simple constitution, and an image forming apparatus including the same. <P>SOLUTION: Non-magnetic carrier C covered with magnetic toner T is conveyed to the vicinity of a regulation blade 36 by magnetism of the magnetic toner T and magnetic force of an S2 pole. The magnetic toner T with which the non-magnetic carrier C is covered adheres to the surface of a developing roller 35 by a potential difference between the regulation blade 36 and the developing roller 35 and the magnetic force of the S2 pole. Since a minimum particle size of the non-magnetic carrier C is larger than the interval of a regulation part 50, the non-magnetic carrier C is not conveyed to the outside (downstream side) of the regulation blade 36 but is accumulated while rotating on the inside (upstream side) of the regulation blade 36 by rotation of the developing roller 35, whereby the magnetic toner T is supplied to the surface of the developing roller 35. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a developing device mounted on an image forming apparatus such as a copying machine, a printer, and a facsimile using an electrophotographic method, and an image forming apparatus including the developing device, and more particularly, to hold only charged toner on a toner carrier. The present invention relates to a developing device that develops an electrostatic latent image on an image carrier in a non-contact manner.

  Conventionally, as a developing method using dry toner in an image forming apparatus using an electrophotographic process, a one-component developing method using no carrier and a two-component developer charging a non-magnetic toner using a magnetic carrier are used. There is known a two-component development system in which an electrostatic latent image on a photosensitive member is developed by a magnetic brush composed of toner and a magnetic carrier formed on a developing roller.

  As the one-component development method, for example, there are a magnetic one-component development method using a magnetic toner as disclosed in Patent Document 1 and a non-magnetic one-component development method using a non-magnetic toner. In the magnetic one-component development system, the toner in the developing device is controlled by magnetic force, and the toner is gently charged between a regulating blade installed in a non-contact manner with the developing roller and a magnet in the developing roller. Therefore, there is an advantage that the image quality can be maintained over a long period of time with little toner deterioration. On the other hand, the frictional charging performance with respect to the toner is insufficient, and it is difficult to obtain high toner charging. For this reason, during jumping development in which toner is allowed to fly to the photoreceptor, toner scattering occurs during transfer onto the recording medium, or moisture in the recording medium evaporates due to heat during fixing, resulting in a so-called tailing phenomenon. There is a problem that occurs.

  On the other hand, in the non-magnetic one-component development method, the toner is strongly frictionally charged between the developing roller and the elastic regulating blade that contacts the developing roller, so that toner scattering and tailing phenomenon hardly occur, and a good initial image is obtained. There is an advantage that it can be obtained. On the other hand, the deterioration of the toner is likely to be promoted by physical stress from the elastic regulating blade, and it is difficult to maintain the image quality for a long period of time.

  On the other hand, in the two-component development system, the toner is charged while being mixed with the magnetic carrier in the developing device, so that a stable charge amount can be maintained for a long period of time, and the life of the toner can be extended. Is suitable. However, because the above-described magnetic brush is used for development while being in physical contact with the surface of the photoreceptor, image disturbance due to the magnetic brush, which is called sweeping unevenness, tends to occur, which is disadvantageous in terms of image quality.

  Further, in Patent Document 2, magnetic development is performed so that the development pole has a plurality of peaks and valleys between the peaks, and development is performed using any one of the magnetic force peaks, so that the unevenness of sweeping by the magnetic brush and the carrier can be obtained. Although a method for suppressing adhesion has been proposed, it has not been sufficient.

  As one means for solving the above-mentioned problem, for example, as shown in Patent Document 3, development is performed by using a magnetic roller (toner supply member) so that the developer is placed in non-contact with the photoreceptor (image carrier). When transferring onto the roller (toner carrier), only the non-magnetic toner is transferred onto the developing roller while leaving the magnetic carrier on the magnetic roller to form a thin toner layer, and the static electricity on the photosensitive member is generated by an AC electric field. A developing method for attaching toner to an electrostatic latent image has been proposed.

  In the case of the development method of Patent Document 3, a high-quality image without toner scattering and unevenness in sweeping with a magnetic brush can be obtained. However, since a magnetic roller is required in addition to the development roller, the manufacturing cost increases and the development device There was a problem that led to an increase in size and complexity.

Japanese Patent Laid-Open No. 5-66680 JP 2000-338783 A JP 2004-318092 A

  In view of the above problems, an object of the present invention is to provide a developing device and an image forming apparatus including the same that can simultaneously eliminate toner scattering due to charging failure and sweeping unevenness due to a magnetic brush with a simple configuration.

  To achieve the above object, the present invention provides a housing for storing a two-component developer composed of a magnetic toner and a non-magnetic carrier, and an image carrier that carries the magnetic toner in the housing and is arranged in a non-contact manner. A toner carrier to be supplied to the body, and a fixed magnet body having a plurality of magnetic poles disposed in the toner carrier and including a main pole disposed in the vicinity of a developing region where the image carrier and the toner carrier face each other A regulating blade disposed at a predetermined interval smaller than the minimum particle diameter of the non-magnetic carrier with respect to the toner carrier, and voltage applying means for applying a DC voltage and an AC voltage to the toner carrier. The developing device provided.

  According to the present invention, in the developing device configured as described above, a potential difference in a direction in which the magnetic toner moves toward the toner carrier is provided between the regulating blade and the toner carrier.

  According to the present invention, in the developing device configured as described above, the minimum particle diameter of the nonmagnetic carrier is at least twice the interval between the regulating blade and the toner carrier.

  The present invention also provides an image forming apparatus including the developing device having the above-described configuration.

  According to the first configuration of the present invention, by disposing the regulating blade at a predetermined interval smaller than the minimum particle diameter of the non-magnetic carrier with respect to the toner carrier, only the magnetic toner can be separated from the toner carrier and the regulating blade. The non-magnetic carrier is blocked on the upstream side of the regulating blade, and thus a highly charged and uniform thin toner layer can be formed on the toner carrier with a simple configuration, resulting in poor charging of the toner. Toner scattering can be suppressed. Further, unlike the conventional two-component development system, a magnetic brush is not formed on the toner carrier, and good magnetic jumping development is performed in the development region, so that unevenness in sweeping with the magnetic brush can be eliminated.

  According to the second configuration of the present invention, in the developing device having the first configuration, a potential difference in a direction in which the magnetic toner moves toward the toner carrier is provided between the regulating blade and the toner carrier. Since the magnetic toner is forcibly attached onto the toner carrier, a uniform toner thin layer can be formed smoothly and stably.

  According to the third configuration of the present invention, in the developing device having the first or second configuration, the minimum particle diameter of the nonmagnetic carrier is set to be twice or more the interval between the regulating blade and the toner carrier. This makes it possible to efficiently sort (separate) the magnetic toner and the non-magnetic carrier by the regulating blade.

  Further, according to the fourth configuration of the present invention, by mounting the developing device having any one of the first to third configurations, toner scattering due to charging failure and sweeping by a magnetic brush can be performed with a simple and low-cost configuration. An image forming apparatus that can eliminate unevenness at the same time and stably output high-quality images.

1 is a schematic configuration diagram showing an overall configuration of an image forming apparatus including a developing device of the present invention. Side sectional view of the developing device of the present invention Top view of the developing device as seen from above Partial enlarged view around the developing roller in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram illustrating an overall configuration of an image forming apparatus including a developing device of the present invention, and the right side is illustrated as a front side of the image forming apparatus. As shown in FIG. 1, the image forming apparatus 100 includes a paper feed cassette 2 that stores sheets stacked on the lower part of the main body. Above this paper feed cassette 2 is formed a paper transport path 4 that extends substantially horizontally from the front of the main body to the rear of the main body and further extends upward to reach the paper discharge section 3 formed on the upper surface of the main body. A pickup roller 5, a feed roller 6, an intermediate conveyance roller 7, a registration roller pair 8, an image forming unit 9, a fixing unit 10, and a discharge roller pair 11 are arranged in this order from the upstream side along the conveyance path.

  The paper feed cassette 2 is provided with a paper stacking plate 12 that is rotatably supported with respect to the paper feed cassette 2 by a rotation fulcrum 12a provided at the rear end in the paper transport direction. The paper stacked on the paper 12 is pressed against the pickup roller 5. A retard roller 13 is disposed on the front side of the paper feed cassette 2 so as to be in pressure contact with the feed roller 6. When a plurality of sheets are fed simultaneously by the pickup roller 5, these feed rollers 6 are fed. A sheet is rolled by the roller 6 and the retard roller 13, and only the uppermost sheet is conveyed.

  Then, the sheet fed by the feed roller 6 and the retard roller 13 is conveyed to the registration roller pair 8 by changing the conveyance direction to the rear of the apparatus by the intermediate conveyance roller 7, and the timing is adjusted by the registration roller pair 8. Are supplied to the image forming unit 9.

  The image forming unit 9 forms a predetermined toner image on a sheet by an electrophotographic process. The photosensitive drum 14 is an image carrier that is pivotally supported in a clockwise direction in FIG. Above the charging device 15, the developing device 16, the cleaning device 17, the transfer roller 18 disposed so as to face the photosensitive drum 14 across the paper conveyance path 4, and the photosensitive drum 14. An exposure unit (LSU) 19 is arranged, and a toner container 20 for supplying toner to the developing device 16 is arranged above the developing device 16.

  The charging device 15 is provided with a conductive rubber roller 15 a connected to a power source (not shown), and the conductive rubber roller 15 a is disposed so as to contact the photosensitive drum 14. Then, when the photosensitive drum 14 rotates, the conductive rubber roller 15a comes into contact with the surface of the photosensitive drum 14 and is driven to rotate. At this time, a predetermined voltage is applied to the conductive rubber roller 15a, whereby the photosensitive drum 14 is rotated. The surface of the film is uniformly charged.

  Next, an electrostatic latent image based on the image data input on the photosensitive drum 14 is formed by the laser beam from the exposure unit (LSU) 19, and toner is attached to the electrostatic latent image by the developing device 16, and the photosensitive member. A toner image is formed on the surface of the drum 14, and the transfer roller 18 transfers the toner image on the surface of the photosensitive drum 14 to the sheet supplied to the transfer position formed in the nip portion between the photosensitive drum 14 and the transfer roller 18. It is transcribed.

  The sheet on which the toner image has been transferred is separated from the photosensitive drum 14 and conveyed toward the fixing unit 10. The fixing unit 10 is disposed on the downstream side of the image forming unit 9 in the sheet conveyance direction, and the sheet on which the toner image is transferred in the image forming unit 9 includes a heating roller 21 provided in the fixing unit 10 and the heating roller 21. The toner image heated and pressed by the pressure roller 22 pressed against the heating roller 21 is fixed on the toner image transferred to the paper.

  The paper on which the image is formed in the image forming unit 9 and the fixing unit 10 is discharged to the paper discharge unit 3 by the discharge roller pair 11. On the other hand, the toner remaining on the surface of the photosensitive drum 14 after the transfer is removed by the cleaning device 17. The photosensitive drum 14 is charged again by the charging device 15 and image formation is performed in the same manner.

  Next, the developing device 16 of the present invention will be described in detail with reference to FIGS. FIG. 2 is a side sectional view of the developing device, and FIG. 3 is a plan view of the developing device as viewed from above. 2 corresponds to a cross-sectional view taken along the line XX ′ in FIG. 3, and FIG. 3 shows a state where the cover 31b is removed for convenience of explanation.

  As shown in FIGS. 2 and 3, the developing device 16 includes a housing 31a that contains a two-component developer composed of a magnetic toner and a non-magnetic carrier, and a seal that prevents the toner contained in the housing 31a from leaking outside. A first spiral member 32, a second spiral member 33, a developing roller 35, and a regulation blade 36 are provided in a housing 31 that is configured from a cover 31 b that stops.

  The interior of the housing 31a is partitioned into a first storage chamber 38 and a second storage chamber 39 by a partition plate 37 extending in the longitudinal direction. The first spiral member 32 is provided in the first storage chamber 38 with a second spiral. A second spiral member 33 is disposed in each storage chamber 39. Further, as shown in FIG. 3, the partition plate 37 is not provided at the left and right ends of the housing 31 a, and this part is a passage through which the developer moves between the first storage chamber 38 and the second storage chamber 39. (Developer delivery unit) 40.

  The first spiral member 32 and the second spiral member 33 are constituted by rotating shafts 32a and 33a and spiral blades 32b and 33b integrally formed on the outer peripheral surface thereof, and are arranged in the housing 31a so as to be substantially parallel to each other. It is pivotally supported by the shaft. Then, the first spiral member 32 and the second spiral member 33 rotate in a predetermined direction so that the developer in the first storage chamber 38 is conveyed in the direction of arrow A, and the developer in the second storage chamber 39 is transferred to arrow B. It is comprised so that it may convey in a direction. Further, a toner supply port 34 through which toner is supplied from the toner container 20 (see FIG. 1) to the cover 31b so that toner can be supplied into the housing 31a according to the detection result of a toner amount detection sensor (not shown). Is provided.

  A motor (not shown) is connected to the rotation shafts 32a and 33a of the first spiral member 32 and the second spiral member 33 through a gear train, and the first and second spiral members 32 and 33 are rotated in a predetermined direction. By driving, the developer is transported through the first storage chamber 38 and the second storage chamber 39, and also passes through the passages 40 provided at the left and right end portions of the housing 31a as described above, so that the first storage chamber is stored. The chamber 38 and the second storage chamber 39 are circulated.

  The developing roller 35 is rotatably supported in the first storage chamber 38 so as to be substantially parallel to the first spiral member 32 and the second spiral member 33, and the first and second spiral members 32 are interposed via a gear train. , 33 is connected to a common motor. A fixed magnet body 35a (see FIG. 4) made of a permanent magnet having a plurality of magnetic poles is fixed inside the developing roller 35. When the developing roller 35 rotates in accordance with the rotation of the photosensitive drum 14, this fixing roller 35a is fixed. Toner adheres (carries) to the surface of the developing roller 35 by the magnetic force of the magnet body 35a to form a toner layer.

  In the developing region D where the photosensitive drum 14 and the developing roller 35 face each other, the toner adhering to the developing roller 35 has a surface potential of the photosensitive drum 14 and a developing bias (described later) applied to the developing roller 35. Due to the potential difference, it flies to the photosensitive drum 14 and adheres to the photosensitive layer, and a toner image is formed on the surface of the photosensitive drum 14. A motor separate from the first spiral member 32 and the second spiral member 33 may be connected to the developing roller 35 so that the developing roller 35 is driven independently.

  The regulating blade 36 regulates the amount of toner supplied to the photosensitive drum 14, that is, the amount of toner adhering to the developing roller 35. For example, a magnetic material such as SUS (stainless steel) is used. The regulating blade 36 is disposed so that a predetermined interval (hereinafter referred to as a regulating portion) is formed between the tip of the regulating blade 36 and the developing roller 35. The amount of toner adhering to the developing roller 35 is regulated by the magnetic field and potential difference, and a thin toner layer of several tens of microns is formed on the surface of the developing roller 35.

  The developing device according to the present invention also has a function of sorting (separating) a small-diameter magnetic toner and a large-diameter non-magnetic carrier according to the interval between the restricting portions and attaching only the magnetic toner onto the developing roller 35. The interval between the restricting portions is set to about 0.1 mm, for example.

  Next, the two-component developer used in the developing device of the present invention will be described. The two-component developer contains a magnetic toner and a nonmagnetic carrier. The weight ratio (T / C) between the magnetic toner and the non-magnetic carrier in the two-component developer is preferably 5 to 20 parts by weight, more preferably 8 to 15 parts by weight with respect to 100 parts by weight of the carrier.

  The magnetic toner is obtained by adding an external additive to toner base particles. The toner base particles contain a binder resin colorant and magnetic powder. The toner base particles may contain a release agent, a charge control agent and the like as necessary. The weight average particle diameter of the toner base particles is preferably 5 to 12 μm, and more preferably 6 to 10 μm. The weight average particle diameter of the toner base particles is measured by a particle size distribution measuring device (for example, Multisizer II type manufactured by Coulter, Inc.). The toner base particles are produced by a known method such as a pulverization classification method, a melt granulation method, a spray granulation method, or a polymerization method.

  Examples of the external additive include inorganic oxides such as silica, titanium oxide, and alumina, and metal soaps such as calcium stearate. The amount of the external additive is usually 0.1 to 5 parts by weight with respect to 100 parts by weight of the toner base particles.

  Examples of nonmagnetic carriers include resin particles made of glass particles, styrene-acrylic copolymers, and the like. The nonmagnetic carrier may contain a conductive agent such as carbon, or may have a coating layer made of a coating resin on the surface. The non-magnetic carrier can be produced, for example, by melt-kneading a resin material with a biaxial kneader and pulverizing and classifying the resin material to a desired particle size. The smaller the particle size of the nonmagnetic carrier, the larger the surface area per unit weight, which is advantageous for frictional charging of the magnetic toner, but it is difficult to select the nonmagnetic carrier C by the regulating blade 36. The minimum particle diameter of the nonmagnetic carrier is preferably about 0.2 mm to 1 mm, more preferably about 0.5 mm.

  4 is a partially enlarged view of the periphery of the developing roller in FIG. A method for forming a toner thin layer on the developing roller 35 in the developing device of the present invention will be described in detail with reference to FIG. As shown in FIG. 4, the fixed magnet body 35 a has three magnetic poles including an N1 pole (main pole) facing the photosensitive drum 14, an S1 pole (separation pole), and an S2 pole (regulation pole). Yes. Since the S2 pole of the fixed magnet body 35a faces the restriction blade 36, a magnetic field attracting the restriction portion 50 is generated by using a magnetic body as the restriction blade 36.

  As described above, the first spiral member 32 and the second spiral member 33 circulate in the developing container 31a while the developer is agitated to sufficiently frictionally charge the magnetic toner T and the nonmagnetic carrier C. The magnetic toner T obtains a high positive charge. At the same time, the non-magnetic carrier C is negatively charged and is thus electrostatically coupled to the magnetic toner T. The non-magnetic carrier C covered with the magnetic toner T is conveyed to the vicinity of the regulating blade 36 by the magnetism of the magnetic toner T and the magnetic force of the S2 pole.

  A DC bias (Vdc = 230 V) and an AC bias (Vpp = 1.5 kV, frequency 2.8 kHz, Duty 50%) are applied to the regulation blade 36 by the regulation bias circuit 51, and the development bias circuit 53 is applied to the development roller 35. Thus, a DC bias (Vdc = 150 V) and an AC bias (Vpp = 1.5 kV, frequency 2.8 kHz, Duty 50%) are applied. Here, since the DC bias applied to the regulating blade 36 is higher on the plus side than the DC bias applied to the developing roller 35, the regulating blade 36 and the developing roller are included in the magnetic toner T covering the nonmagnetic carrier C. A force that moves toward the developing roller 35 acts due to the potential difference from the magnetic field 35 and the magnetic force of the S2 pole.

  Here, the AC blade synchronized with the AC bias applied to the developing roller 35 is also applied to the regulating blade 36 because a certain potential difference based only on the DC component is generated between the regulating blade 36 and the developing roller 35. This is to stabilize the movement of the magnetic toner T in the restricting portion 50. Note that it is not always necessary to apply an AC bias to the regulation blade 36, and only a DC bias may be applied to the regulation blade 36 to generate a potential difference with the developing roller 35.

  As a result, although the magnetic toner T adheres to the surface of the developing roller 35, the minimum particle diameter (0.5 mm) of the nonmagnetic carrier C is larger than the interval (0.1 mm) of the restricting portion 50. It is blocked by the regulating blade 36. That is, the non-magnetic carrier C is not conveyed to the outside (downstream side) of the regulating blade 36, and stays while rolling on the inside (upstream side) of the regulating blade 36 due to the rotation of the developing roller 35, and onto the surface of the developing roller 35. T is supplied. Since the non-magnetic carrier C loses its magnetism as the magnetic toner T is removed from the surface, the non-magnetic carrier C leaves the S2 pole, falls again into the developer, and is agitated by the first and second spiral members 32 and 33.

  On the other hand, the toner thin layer formed on the developing roller 35 passes through the regulating portion 50 by the rotation of the developing roller 35 and is conveyed to the developing region D. Since a developing bias composed of a DC bias and an AC bias is applied to the developing roller 35, the magnetic toner T on the developing roller 35 jumps to the photosensitive drum 14 side due to a potential difference with the photosensitive drum 14, so The electrostatic latent image on the body drum 14 is developed.

  When the developing roller 35 further rotates counterclockwise, a magnetic field attracted by the S1 pole is applied this time, and the magnetic toner T that has not been used to form a toner image is collected in the housing 31a. Further, since the magnetic field repelled by the S1 pole and the S2 pole is applied, the magnetic toner T is detached from the developing roller 35 in the housing 31a. Then, the first spiral member 32 is frictionally charged together with the nonmagnetic carrier C, covers the nonmagnetic carrier C, and is conveyed again to the vicinity of the regulating blade 36 by the magnetic field of the S2 pole.

  According to the configuration of the present invention, the nonmagnetic carrier C can be reliably prevented from flowing to the downstream side of the regulating blade 36 with a simple configuration, and a highly charged and uniform toner thin layer can be formed on the developing roller 35. Therefore, it is possible to suppress toner scattering due to toner charging failure. Further, unlike the conventional two-component development method, a magnetic brush is not formed on the developing roller 35 and good magnetic jumping development is performed in the development region, so that unevenness in sweeping with the magnetic brush can be eliminated.

  Further, when the particle diameter of the nonmagnetic carrier C is less than twice the interval of the restricting portion 50, the tip of the restricting blade 36 is more than the center of the nonmagnetic carrier C when the nonmagnetic carrier C is conveyed to the restricting portion 50. Touch up. Therefore, the non-magnetic carrier C may be sandwiched between the restricting portions 50 to prevent the magnetic toner T from passing therethrough, and vertical stripes may occur in the toner thin layer formed on the developing roller 35. Therefore, by setting the minimum particle diameter of the nonmagnetic carrier C to be twice or more the interval between the restricting portions 50, there is no possibility that the nonmagnetic carrier C is caught between the restricting portions 50, and the magnetic toner T and the nonmagnetic carrier in the restricting portion 50 are eliminated. C can be selected (separated) efficiently.

  Here, a potential difference in the direction in which the magnetic toner T moves toward the developing roller 35 is provided between the regulating blade 36 and the developing roller 35, but the non-magnetic carrier C is located on the inner side (upstream side) of the regulating blade 36. When staying while rolling, the magnetic toner T moves away from the non-magnetic carrier C and moves to the surface of the developing roller 35 by intermolecular force. Therefore, it is not always necessary to apply a DC bias to the regulation blade 36 by the regulation bias circuit 51.

  However, in order to smoothly adhere the toner to the surface of the developing roller 35, it is preferable to provide a potential difference between the regulating blade 36 and the developing roller 35 as in the present embodiment. In the above embodiment, the direct current bias and the alternating current bias applied to the developing roller 35 and the regulating blade 36 are examples, and are appropriately determined according to the composition of the nonmagnetic carrier C and the magnetic toner T, the particle diameter, the interval between the regulating portions 50, and the like. Set it.

  In addition, this invention is not limited to the said embodiment, Embodiment which is obtained by combining each embodiment suitably is also included in this invention, and various changes are possible in the range which does not deviate from the meaning of this invention. For example, in the above embodiment, the developing device using positively charged toner whose charging direction is positive (plus side) has been described as an example. However, the developing device using negatively charged toner whose charging direction is negative (minus side) is described. Is equally applicable. In this case, since the toner moves from a low potential (higher to the negative side) to a higher side (lower to the negative side), the relationship between the potential difference between the regulating blade 36 and the developing roller 35 and between the developing roller 35 and the photosensitive drum 14. Is the opposite of using positively charged toner.

  In addition, the arrangement (peak position) and magnetic strength of each of the magnetic poles N1, S1, and S2 of the fixed magnet body 35a may be set as appropriate according to the specifications of the developing device, the characteristics of the developer, and the like. In addition to the three-pole structure, a fixed magnet body 35a having a five-pole structure or a seven-pole structure, for example, may be used.

  Further, the image forming apparatus on which the developing device of the present invention is mounted is not limited to the monochrome printer as shown in FIG. 1, but other image forming apparatuses such as monochrome and color copiers, color printers, and facsimiles. Also good.

  INDUSTRIAL APPLICABILITY The present invention is applicable to a developing device using a two-component developer composed of a magnetic toner and a non-magnetic carrier. Thus, it is possible to provide a developing device that can simultaneously solve the unevenness of sweeping by the magnetic brush with a simple configuration.

14 Photosensitive drum (image carrier)
16 Developing Device 17 Cleaning Device 31 Housing 32 First Spiral Member 33 Second Spiral Member 35 Developing Roller (Toner Carrier)
35a Fixed magnet body 36 Restriction blade 37 Partition plate 38 First storage chamber 39 Second storage chamber 50 Restriction portion 51 Restriction bias circuit 53 Development bias circuit (voltage application means)
100 Image forming apparatus T Magnetic toner C Non-magnetic carrier D Development area

Claims (4)

A housing that contains a two-component developer comprising a magnetic toner and a non-magnetic carrier;
A toner carrier that carries the magnetic toner in the housing and supplies the magnetic toner to an image carrier that is arranged in a non-contact manner and opposed thereto;
A fixed magnet body having a plurality of magnetic poles including a main pole disposed in the vicinity of a developing region disposed in the toner bearing body, the image bearing body and the toner bearing body facing each other;
A regulating blade disposed at a predetermined interval smaller than the minimum particle diameter of the non-magnetic carrier with respect to the toner carrier;
Voltage application means for applying a DC voltage and an AC voltage to the toner carrier;
A developing device comprising:   The developing device according to claim 1, wherein a potential difference in a direction in which the magnetic toner moves toward the toner carrier is provided between the regulation blade and the toner carrier.   3. The developing device according to claim 1, wherein a minimum particle diameter of the non-magnetic carrier is at least twice an interval between the regulating blade and the toner carrier.   An image forming apparatus comprising the developing device according to claim 1.

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