JP2009265358A - Developing unit and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably and optimally regulate layer thickness of two-component developer by suppressing the used amount of high permeability material in a developer regulating member for regulating the layer thickness of the two-component developer on developer carrier as well as having sufficient magnetic force work between the developer carrier and the developer regulating member. <P>SOLUTION: The developing unit 18 is provided with: the developer containing a non-magnetic toner and magnetic carrier; a housing 20 for storing the developer; a developer carrier 39 for carrying the developer on an outer periphery surface thereof; and a developer regulating member 29 which is arranged facing an outer periphery surface of the developer carrier 39 with a prescribed gap kept therebetween for regulating the layer thickness of the developer which is carried on the developer carrier 39. In this case, the developer regulating member 29 is composed of a substrate 51 which is attached directly or through another member to the housing 20 and a high permeability layer 52 covering at least a chip of the developer carrier 39 in the substrate 51 and the relative permeability of the high permeability material composing the high permeability layer 52 is made higher than that of the substrate 51. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developing device using a so-called two-component developer, and an electrophotographic image forming apparatus including the developing device.

  An electrophotographic image forming apparatus includes an electrostatic latent image carrier that carries an electrostatic latent image on an outer peripheral surface, and a developing device that develops toner by attaching toner to the electrostatic latent image on the electrostatic latent image carrier And have.

  As a developing device, a type using a so-called two-component developer composed of a non-magnetic toner and a magnetic carrier has been proposed. As in the conventional example shown in FIG. 3, this type of developing device 118 is housed inside a housing 120 containing a two-component developer, a rotatable cylindrical sleeve (developer carrier) 139 and a cylindrical sleeve 139. A developing roller 128 including a cylindrical fixed magnet 138 and a plate-like developer regulating member 129 disposed to face the developing roller 128 with a regulating region 172 interposed therebetween.

  When the developing device 118 shown in FIG. 3 is driven, the developer in the housing 120 is agitated by the agitating members 122 and 124 in the agitating chamber 178 and then attracted to the outer peripheral surface of the cylindrical sleeve 139 by the magnetic force of the fixed magnet 138. Is done. The developer thus carried on the sleeve 139 is conveyed to the regulation region 172 based on the rotation of the sleeve 139, and the developer layer thickness is regulated in the regulation region 172. The developer on the sleeve 39 that has passed through the restriction region 172 is conveyed to a region (development region) 174 facing the electrostatic latent image carrier 104, and in the development region 174, the toner in the developer is electrostatic latent image. The electrostatic latent image is electrically supplied to the electrostatic latent image portion of the carrier 104, whereby the electrostatic latent image is visualized (developed).

  With respect to this type of developing device, techniques using a magnetic member as a developer regulating member have been proposed (see Patent Documents 1 to 4). According to this technique, the layer thickness of the two-component developer on the developer carrying member is not only regulated by mechanical scraping by the developer regulating member, but also between the developer carrying member and the regulating member. It is also regulated by the acting magnetic force. Therefore, it is possible to set a relatively wide gap between the developer carrier and the regulating member, which makes it difficult for foreign matter or toner aggregates to be caught in the gap between the developer carrier and the regulating member. The developer transportability is improved.

JP-A-8-202153 JP 2002-229337 A Japanese Patent Laid-Open No. 11-24407 JP-A-11-190942

  However, since magnetic members such as iron and stainless steel that have been conventionally used as a developer regulating member do not necessarily have sufficiently strong magnetism, the developer can be set with a wide gap between the regulating member and the developer carrier. The layer thickness regulation may become unstable.

  In addition, it is conceivable to use a material having a very high permeability (high permeability material) such as an alloy such as permalloy or supermalloy, or a permanent magnet as a material for the developer regulating member. When used as a whole, there are various problems such as a significant increase in cost and difficulty in securing strength.

  Therefore, the present invention provides a developer regulating member that regulates the layer thickness of the two-component developer on the developer carrying member while suppressing the amount of the high magnetic permeability material used, and between the developer carrying member and the developer regulating member. An object of the present invention is to provide a developing device capable of stably and satisfactorily regulating the layer thickness of a two-component developer by applying a sufficiently strong magnetic force therebetween, and an image forming apparatus including the developing device. And

In order to solve the above problems, a developing device according to the present invention provides:
A developer comprising a non-magnetic toner and a magnetic carrier;
A housing containing the developer;
A developer carrying member carrying the developer on the outer peripheral surface;
In order to regulate the layer thickness of the developer carried on the developer carrier, a developer regulating member disposed opposite to the outer peripheral surface of the developer carrier with a predetermined interval,
The developer regulating member includes a base material attached to the housing directly or via another member, and a high permeability layer that covers at least a tip of the base material on the developer carrier side,
The high magnetic permeability material constituting the high magnetic permeability layer has a relative magnetic permeability higher than that of the base material.

  As used herein, the term “high permeability material” refers to a material having a relative permeability higher than that of a general cold-rolled steel sheet. As a specific high permeability material, for example, And an alloy containing iron and nickel (permalloy, supermalloy, etc.), silicon steel, iron with a purity of 99% or more, or an amorphous alloy containing a ferromagnetic material.

  An image forming apparatus according to the present invention includes the above-described developing device.

  According to the present invention, since the tip of the developer regulating member on the developer carrier side of the base material is covered with the high magnetic permeability layer made of a high magnetic permeability material having a higher relative magnetic permeability than the base material, the developer Therefore, the permeability of the portion of the regulating member facing the developer carrying member, which is a particularly important part for regulating the layer thickness, can be increased. As a result, a sufficiently strong magnetic force can be applied between the developer carrying member and the developer regulating member, so that even if a wide gap between the developer carrying member and the regulating member is secured, the developer carrying The developer on the body can be stably and well regulated. Further, since a sufficient magnetic force can be obtained by the high magnetic permeability layer, a stronger magnetic force is not required for the base material of the regulating member and the magnet inside the developer carrier. Therefore, it is possible to reduce the size of the regulating member and the developer carrying member, and accordingly, it is possible to reduce the size of the developing device. Furthermore, according to the present invention, the amount of the high magnetic permeability material used can be suppressed as compared with the case where the entire regulating member is made of the high magnetic permeability material. Therefore, the cost can be suppressed even when an expensive high permeability material such as a magnet containing a rare earth element is used, and the strength of the entire regulating member can be reduced even when a high permeability material such as a ferrite magnet is used. It becomes easy to secure.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. In the following description, terms indicating a specific direction (for example, “up”, “down”, “left”, “right”, and other terms including them, “clockwise direction”, “counterclockwise” ”) Is used to facilitate understanding of the invention with reference to the drawings, and the present invention should not be construed as being limited by the meaning of these terms. In the image forming apparatus described below, the same reference numerals are used for the same or similar components.

  FIG. 1 shows a schematic configuration of an image forming apparatus 2 according to an embodiment of the present invention. The image forming apparatus 2 is an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multi-function machine having a combination of these functions. Currently, various types of electrophotographic image forming apparatuses have been proposed. The illustrated image forming apparatus is a so-called tandem color image forming apparatus. However, the present invention is not applied only to this type of image forming apparatus, and may be applied to, for example, a so-called four-cycle color image forming apparatus or a monochrome output image forming apparatus.

  The image forming apparatus 2 includes an endless intermediate transfer belt 30. Under the intermediate transfer belt 30, toners of corresponding colors using yellow (Y), magenta (M), cyan (C), and black (K) developers in order from the left side to the right side in the drawing. Four image forming units 3 (3Y, 3M, 3C, 3K) for generating an image are arranged along the intermediate transfer belt 30.

  Each image forming unit 3 includes a cylindrical photosensitive member 4 as an electrostatic latent image carrier. Around the photoconductor 4, in order along the rotation direction (clockwise direction in the drawing), a charging device 8 for charging the outer peripheral surface of the photoconductor 4 and an image are projected onto the photoconductor 4 to electrostatically charge each color. An exposure device 6 for forming a latent image; a developing device 18 for supplying each color toner to the photosensitive member 4 to make the electrostatic latent image visible; a primary transfer roller 14 for pressing the intermediate transfer belt 30 together with the photosensitive member 4; A photosensitive member cleaning member 16 for scraping off the toner on the photosensitive member 4 is disposed.

  On the intermediate transfer belt 30, toner cartridges 10 (10Y, 10M) containing yellow (Y), magenta (M), cyan (C), and black (K) toner in order from the left side to the right side in the drawing. , 10C, 10K) are arranged along the intermediate transfer belt 30. Each toner cartridge 10 is connected to a corresponding color developing device 18 via a connecting pipe 11.

  In each image forming unit 3, the toner image formed on the photoconductor 4 is transferred (primary transfer) from the photoconductor 4 to the belt 30 at a nip portion (primary transfer region) between the photoconductor 4 and the belt 30. During the primary transfer, yellow, magenta, cyan, and black toner images are superimposed on the belt 30 to form a full-color toner image.

  A secondary transfer roller 42 that clamps the recording sheet 36 together with the belt 30 is provided outside the belt portion supported by the roller 32 arranged on the right side in the drawing. The recording sheet 36 is conveyed from the paper supply unit 44 to the nip portion (secondary transfer region 41) between the secondary transfer roller 42 and the belt 30. In the secondary transfer area 41, the toner image on the belt 30 is transferred (secondary transfer) to the recording sheet 36.

  After the secondary transfer, the recording sheet 36 is conveyed to the fixing unit 40 where the toner image is fixed on the recording sheet 36. After fixing, the recording sheet 36 is conveyed to a paper discharge unit 46 provided, for example, at the top of the image forming apparatus 2. On the other hand, after the secondary transfer, the untransferred toner remaining on the belt 30 is transported to the nip portion (cleaning region 13) between the belt 30 and the cleaning member 12 by the rotation of the belt 30, and in the cleaning region 13 by the cleaning member 12. It is scraped off.

  For example, a control unit 48 that controls various operations of the image forming apparatus 2 is provided in the upper left part of the image forming apparatus 2. However, the control unit 48 can be provided at an arbitrary position of the image forming apparatus 2.

  The configuration of the developing device 18 will be specifically described with reference to FIG.

  As shown in FIG. 2, the developing device 18 includes a housing 20 that houses a two-component developer containing nonmagnetic toner and a magnetic carrier and various members described below. In order to facilitate understanding of the invention by simplifying the drawing, a part of the housing 20 is omitted in FIG.

  The housing 20 includes an opening 70 opened toward the photosensitive member 4, and a developing roller 28 is provided in a space near the opening 70. The developing roller 28 is disposed in parallel to the photosensitive member 4 and opposed to the outer peripheral surface of the photosensitive member 4 via a predetermined developing gap 74. The developing roller 28 includes a columnar fixed magnet 38 and a rotatable cylindrical sleeve (developer carrier) 39 provided so as to surround the fixed magnet 38. The sleeve 39 is connected to a power source (not shown) as a bias applying device, and a predetermined developing bias is applied to the sleeve 39 by turning on the power source. For example, the developing bias is constituted by a voltage obtained by superimposing an AC voltage and a DC voltage. In this case, an oscillating electric field is formed between the sleeve 39 and the photosensitive member 4.

  A developer returning member 50 fixed to the housing 20 is disposed opposite to the side of the sleeve 39. The developer return member 50 is made of, for example, metal, but various materials can be used for the developer return member 50, and a plating layer may be provided on the surface of the developer return member 50 as necessary. .

  A plate-like developer regulating member 29 fixed to the housing 20 via a developer return member 50 is disposed oppositely with a predetermined regulating gap 72 diagonally above the sleeve 39. A specific configuration of the developer regulating member 29 will be described later. In the inner portion of the sleeve 39 portion facing the developer regulating member 29, the fixed magnet 38 is provided with an N-pole or S-pole magnetic pole.

  Note that a power supply (not shown) may be connected to the developer return member 50 and / or the developer regulating member 29. In this case, the developer return member 50 and / or the developer is turned on by turning on the power supply. A bias for making it difficult for the developer to adhere to the sleeve 39 of the agent regulating member 29 can be applied.

  A developer stirring chamber 78 is formed in the space behind the developing roller 28, specifically in the space below the developing roller 28. The stirring chamber 78 has a front chamber 80 formed in the vicinity of the developing roller 28 and a rear chamber 82 separated from the developing roller 28. A front screw 24, which is a pre-stirring conveyance member that conveys the developer while stirring the developer from the front surface to the back surface of the drawing, is rotatably disposed in the front chamber 80, and the rear chamber 82 is rotated from the back surface to the front surface of the drawing. A rear screw 22 that is a rear stirring member transporting member that transports the developer while stirring is disposed rotatably. The front chamber 80 and the rear chamber 82 are separated by a partition wall 84 provided therebetween. The partition portions in the vicinity of both ends of the front chamber 80 and the rear chamber 82 are removed to form a communication passage, and the developer that has reached the downstream end of the front chamber 80 is sent to the rear chamber 82 through the communication passage. In addition, the developer that has reached the downstream end of the rear chamber 82 is fed into the front chamber 80 via a communication passage. In the rear chamber 82 of the stirring chamber 78, for example, a toner concentration sensor (not shown) is attached to the housing 20.

  The operation of the developing device 18 configured as described above will be described. During image formation, the sleeve 39 of the developing roller 28 rotates in the clockwise direction in the drawing based on the driving of a motor (not shown). Further, the front screw 24 and the rear screw 22 rotate counterclockwise in the drawing. As a result, the developer contained in the developer stirring chamber 78 is stirred while being circulated and conveyed through the front chamber 80 and the rear chamber 82. As a result, the toner and the carrier contained in the developer come into frictional contact with each other and are charged with opposite polarities. In the embodiment, it is assumed that the carrier is positively charged and the toner is negatively charged. Further, the toner newly supplied from the toner cartridge 10 is mixed with the existing developer by stirring in the stirring chamber 78.

  The charged developer is supplied to the developing roller 28 in the process of being conveyed through the front chamber 80 by the front screw 24 and is carried on the outer peripheral surface of the developing roller 28. Specifically, the developer is attracted to the outer peripheral surface of the sleeve 39 by the magnetic force of the fixed magnet 38 of the developing roller 28. Thus, the developer carried on the sleeve 39 of the developing roller 28 is conveyed in the clockwise direction in the drawing based on the rotation of the sleeve 39. When the developer on the sleeve 39 is transported to a region facing the developer return member 50, the developer exceeding the appropriate transport amount is pushed back to the stirring chamber 78 by the developer return member 50, thereby The developer conveyance amount is adjusted. When the developer on the sleeve 39 whose transport amount has been adjusted in this manner is transported to a region facing the restricting member 29 (a restricting region 72), the layer thickness of the developer passing through the restricting region 72 is a predetermined amount. Regulated by When the developer that has passed through the regulation region 72 reaches the region (development region 74) facing the photosensitive member 4 based on the rotation of the sleeve 39, the presence of an electric field formed between the sleeve 39 and the photosensitive member 4 exists. Thus, the toner adhering to the carrier is electrically supplied to the electrostatic latent image portion on the photoreceptor 4.

  When the toner is consumed by the development performed in this manner, it is preferable that a toner corresponding to the consumed amount is supplied to the developer. Therefore, the toner concentration (mixing ratio of toner and carrier) in the housing 20 of the developing device 18 is detected by the toner concentration sensor, and controlled by the control unit 48 so that a predetermined toner replenishing operation is performed based on the detection result. . When a toner replenishing operation is performed under the control of the control unit 48, a toner replenishing mechanism (not shown) is activated, and the toner accommodated in the toner cartridge 10 is replenished appropriately into the housing 20 of the developing device 18 via the connection pipe 11. Is done.

  Hereinafter, the configuration of the developer regulating member 29 will be specifically described.

  The developer regulating member 29 is a long plate-like member that extends along the axial direction of the sleeve 39. In the present embodiment, the cross-sectional shape of the developer regulating member 29 is substantially rectangular. However, the cross-sectional shape of the developer regulating member 29 is not particularly limited. For example, the developer regulating member 29 has a quadrilateral shape other than a rectangular shape, a triangular shape, or a pentagonal shape. It may be a square or a shape including an arc in a part of the outline.

  The developer regulating member 29 includes a base 51 attached to the housing 20 via a developer return member 50 and a high permeability layer 52 that covers the tip of the base 51 on the sleeve 39 side.

  Various materials different from the material of the high magnetic permeability layer 52 can be used for the base material 51. The base material 51 is preferably made of a magnetic material such as iron or stainless steel, but a nonmagnetic material such as a resin may be used as long as a sufficient magnetic force can be obtained by the high permeability layer 52.

  The thickness of the high magnetic permeability layer 52 in the portion covering the tip of the base material 51 is preferably 0.1 μm or more, whereby the disappearance of the high magnetic permeability layer 52 due to wear can be prevented. In addition, since the high magnetic permeability layer 52 is partially provided on the regulating member 29, the amount of the high magnetic permeability material used can be suppressed as compared with the case where the entire regulating member 29 is made of a high magnetic permeability material. Can do. Therefore, even when an expensive high permeability material is used, the cost of the regulation member 29 can be suppressed, and even when a high permeability material having a low strength is used, it is easy to ensure the strength of the regulation member 29 as a whole.

  For the high magnetic permeability layer 52, various high magnetic permeability materials can be used. The relative magnetic permeability of the high magnetic permeability material constituting the high magnetic permeability layer 52 is preferably 2000 or more, and more preferably 4000 or more. The relative permeability is higher than that of a general cold-rolled steel sheet. By using such a material having a high relative permeability for the high permeability layer 52, the layer thickness of the developer is particularly restricted. It is possible to increase the permeability of the portion of the regulating member 29 facing the sleeve 39, which is an important part, so that the gap between the regulating member 29 and the sleeve 39 is sufficient regardless of the type of material of the substrate 51. Can exert a strong magnetic force. Therefore, even if the gap between the regulating member 29 and the sleeve 39 is set to be relatively wide, the developer layer thickness on the sleeve 39 can be regulated stably and satisfactorily. Further, since a sufficiently strong magnetic force can be obtained by the high magnetic permeability layer 52, the base member 51 of the restricting member 29 and the fixed magnet 38 of the developing roller 28 are not required to have a strong magnetic force as in the related art. The roller 28 can be reduced in size, and accordingly, the developing device 18 can be reduced in size.

  As the high permeability material constituting the high permeability layer 52, a material having a higher relative permeability than a general cold rolled steel sheet is used. Specifically, for example, silicon steel, iron having a purity of 99% or more is used. An alloy containing iron and nickel, an amorphous alloy containing a ferromagnetic material, or the like is used. When silicon steel is used as the high magnetic permeability material, the silicon content is preferably about 3 to 4%, whereby the magnetic properties of the high magnetic permeability material can be made sufficiently strong. When iron is used as the high magnetic permeability material, specifically, for example, iron having a purity of about 99.95% (so-called pure iron) is used. High-purity iron not only has high magnetic permeability, but also has an advantage of excellent corrosion resistance. Specific examples of the alloy containing iron and nickel include, for example, permalloy (an iron alloy having a nickel content of about 79%) and supermalloy (a molybdenum content of about 5% and a nickel content of about 79% iron alloy), or Mu-Metal (an alloy made of iron, nickel, molybdenum and copper). As an amorphous alloy containing a ferromagnetic material, for example, Finemet (registered trademark) manufactured by Hitachi Metals, Ltd. is used.

  The method of forming the high magnetic permeability layer 52 is not particularly limited. For example, a method of fixing a high magnetic permeability material to the base 51 using a fixing tool such as a screw or a pin, at least a sleeve of the base 51 A method of plating the surface including the tip side on the 39 side, a method of directly bonding a high magnetic permeability material to the base material 51 (high temperature bonding, friction bonding, bonding by laser irradiation method, etc.), adhesive or minimum For example, a method of bonding a high magnetic permeability material to the base material 51 using a brazing material, or a method of forming a film on the surface of the base material 51 including at least the tip surface on the sleeve 39 side by vacuum deposition, or the like. A specific method for forming the high magnetic permeability layer 52 by plating includes a method of applying an alloy plating made of iron, cobalt, and nickel. This method is known as a method for producing a magnetic disk head. is there.

  Hereinafter, as a second embodiment, an embodiment in which the high permeability layer 52 is configured such that the portion near the sleeve 39 has a higher permeability will be described. Other configurations in the second embodiment are the same as those in the above-described embodiment, and the structure of the developing device 18 and its constituent members is as shown in FIG.

  In the second embodiment, it is preferable that the portion of the high permeability layer 52 having a specific permeability of a predetermined value or more has a thickness of 0.1 μm or more, and thereby, the high permeability layer 52 on the sleeve 39 side. Even when the tip portion is worn, it is possible to prevent the portion having a relative magnetic permeability greater than or equal to the predetermined value in the high magnetic permeability layer 52 from being lost. Note that the relative magnetic permeability of the portion is preferably 2000 or more, and more preferably 4000 or more.

  Various methods can be adopted as a method of forming the high magnetic permeability layer 52 so that the magnetic permeability of the portion closer to the sleeve 39 is higher. For example, only the end surface of the high magnetic permeability layer 52 on the sleeve 39 side can be used. A method of changing the crystallinity of the high-permeability layer 52 by performing a heat treatment by contacting a heat source can be used. In this case, since the portion near the sleeve 39 is strongly affected by the heat treatment, the high permeability layer 52 changes its crystallinity so that the portion near the sleeve 39 has a higher permeability. According to this method, since it is not necessary to heat treat the entire material constituting the high magnetic permeability layer 52, the processing time can be shortened and the processing temperature can be reduced, thereby increasing the productivity of the regulating member 29. It can be improved. When this method is employed, the high permeability layer 52 may be formed of a material different from the base material 51, or the entire regulating member 29 is formed of one material, and the heat treatment applied to the material. The portion may be the high permeability layer 52. In the former case, since the bonded portion between the base material 51 and the high magnetic permeability layer 52 is away from the heat treatment portion, it is possible to avoid problems such as easy peeling due to the influence of the heat treatment.

  As another method of forming the high magnetic permeability layer 52 so that the magnetic permeability of the portion closer to the sleeve 39 becomes higher, the high magnetic permeability layer 52 is composed of a plurality of high magnetic permeability materials, and these high magnetic permeability materials are used as the sleeve. A method of arranging them so that the magnetic permeability is closer to 39 and joining them together is conceivable. In this method, if the bonding between the materials is a high-temperature bonding or a friction bonding, an intermetallic compound may be generated on the bonding surface between the materials. In this case, in a state where the regulating member 29 is completed, a high magnetic permeability is obtained. Since the magnetic permeability of the joint between the materials is intermediate between the magnetic permeability of the high magnetic permeability materials on both sides of the joint, as a result, the magnetic permeability is increased so that the permeability becomes higher as the sleeve 39 is closer. A magnetic layer 52 is formed.

  While the present invention has been described with reference to the above-described embodiments, the present invention is not limited to the above-described embodiments.

  For example, in the above-described embodiment, the configuration in which the base member 51 of the regulating member 29 is attached to the housing 20 via the developer return member 50 has been described. However, in the present invention, the base member 51 is other than the developer return member 50. You may make it attach to the housing 20 via the member of this, or may attach to the housing 20 directly.

  Moreover, in the above-mentioned embodiment, although the structure which the surface part of the base material 51 other than the part covered with the high magnetic permeability layer 52 was exposed was demonstrated, it covered with the high magnetic permeability layer 52 in this invention. You may make it cover the surface part of the base materials 51 other than a part with the coating layer aiming at protecting the base material 51 or providing electroconductivity to the control member 29. FIG.

  Further, in the above-described embodiment, the case where the high magnetic permeability layer 52 is configured to cover only the tip of the base member 51 on the sleeve 39 side has been described. However, in the present invention, the high magnetic permeability layer 52 is a base layer. What is necessary is just to comprise so that the front-end | tip at the side of the sleeve 39 of the material 51 may be covered, for example, you may comprise so that the whole surface of the base material 51 may be covered.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to the present invention. It is sectional drawing which shows the developing device based on this invention. It is sectional drawing which shows the prior art example of a developing device.

Explanation of symbols

2: image forming apparatus, 3: image forming unit, 4: photoconductor (electrostatic latent image carrier), 10: toner cartridge, 18: developing device, 20: housing of developing device, 22: rear screw, 24: front Screw 26: supply roller 28: developing roller 29: regulating member 30: intermediate transfer belt 36: recording sheet 38: fixed magnet 39: sleeve (developer carrier) 48: control unit 50: Developer return member, 51: base material, 52: high permeability layer, 72: restriction region, 74: development region, 78: developer stirring chamber, 80: front chamber, 82: rear chamber.

Claims (6)

A developer comprising a non-magnetic toner and a magnetic carrier;
A housing containing the developer;
A developer carrying member carrying the developer on the outer peripheral surface;
In order to regulate the layer thickness of the developer carried on the developer carrier, a developer regulating member disposed opposite to the outer peripheral surface of the developer carrier with a predetermined interval,
The developer regulating member includes a base material attached to the housing directly or via another member, and a high permeability layer that covers at least a tip of the base material on the developer carrier side,
A developing device characterized in that a relative permeability of a high permeability material constituting the high permeability layer is higher than a relative permeability of the substrate.   The developing device according to claim 1, wherein the high permeability material has a relative permeability of 2000 or more.   The developing device according to claim 2, wherein the high magnetic permeability material has a relative magnetic permeability of 4000 or more.   The developing device according to claim 1, wherein a thickness of the high permeability layer in a portion covering the tip of the base material is 0.1 μm or more.   The high magnetic permeability material is any one of an alloy containing iron and nickel, silicon steel, iron with a purity of 99% or more, or an amorphous alloy containing a ferromagnetic material. The developing device according to claim 1.   An image forming apparatus comprising the developing device according to claim 1.

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