JP2005266406A - Developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device having simple structure, reducing the cost of components and production and capable of maintaining fine picture quality by suppressing the variation of toner density by autonomously correcting the deviation of developer distribution even when the developing device or an image forming apparatus on which the developing device is mounted is arranged obliquely from a horizontal direction. <P>SOLUTION: A developer stirring member has a plurality of blade parts arranged in parallel along the axial direction of a developer carrier and aperture parts arranged in the vicinity of the roots of the blade parts and connected to a hollow part in the developer stirring member are formed at least on both end parts along the axial direction of the developer stirring member. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as a copying machine, a printer, a facsimile, or a multifunction machine having these functions, to which an electrophotographic system is applied, and in particular, a two component having a magnetic carrier and a toner. The present invention relates to an improvement of a developing device that uses a developer and can autonomously control the toner density without using a toner density detecting means.

Japanese Patent Publication No. 5-67233 JP-A-5-119625 Japanese Patent Laid-Open No. 9-22178 JP 2000-352877 A JP-A-9-197833 JP-A-61-212864 Japanese Patent Laid-Open No. 2001-42615 Japanese Patent Laid-Open No. 2001-42616

  Conventionally, as a developing device used in an image forming apparatus such as a copying machine, a printer, a facsimile, or a multifunction machine having these functions to which this kind of electrophotographic method is applied, it is formed on an image carrier such as a photosensitive drum. It is known that the electrostatic latent image formed is visualized with a developer. As a developing method used in such a developing apparatus, a one-component developing method using only toner that is colored particles as a developer, and a two-component method using a mixture of magnetic particles and toner that is colored particles as a developer. Roughly divided into development methods.

  The above two-component developing system has many excellent points such as image quality, cost, and stability. Therefore, there is a wide range of magnetic brush developing systems that develop a toner mixed with a magnetic carrier while conveying the developer by magnetic force. It has been adopted. In this magnetic brush development system, the toner is carried on the surface of the magnetic carrier by the electrostatic force generated by the friction between the toner and the magnetic carrier. When this toner approaches the electrostatic latent image on the image carrier, By flying on the electrostatic latent image by the electric field formed by the electrostatic latent image, the electrostatic latent image is visualized. Further, the developer is repeatedly used while replenishing the toner consumed by the development.

  However, in such a magnetic brush development system, if the toner density (mixing ratio of toner and magnetic carrier) is not controlled to be within a certain range, toner scattering and fogging occur when the toner density increases. On the other hand, when the toner density is lowered, density spots and image omissions occur. Therefore, in order to obtain a stable image, it is necessary to keep the toner density constant.

  Therefore, in the conventional magnetic brush developing system, in order to obtain a stable image, a toner density sensor and a toner replenishing member are mounted on the developing device and control is performed to keep the toner density constant. For example, the toner density is detected by the toner density sensor, and after determining that the toner density has decreased based on the detection information, the toner supply is performed by the toner supply member.

  However, in this type of magnetic brush developing system, a toner density sensor and a toner replenishing member are indispensable, and an increase in the size and cost of the developing device cannot be avoided. In addition, there is a problem that the toner density detection system is troublesome, such as creating a density patch to be detected.

  As a prior art for avoiding such difficulties, there has already been proposed a developing device that keeps the toner density constant without using a toner density sensor or a toner replenishing member. The developing device includes a developer accommodating portion that accommodates a two-component developer, and a toner accommodating portion that communicates with the developer accommodating portion and accommodates toner, and the amount of the two-component developer on the developer carrier is set. It is configured to regulate the toner concentration by regulating the toner by autonomously controlling the toner intake of the two-component developer according to the change in the toner concentration of the two-component developer on the developer carrying member. is there.

  This autonomous toner density control method generates a developer moving layer carried and conveyed by a developer carrying member and a developer circulating layer in which the developer circulates in the developer containing portion. The toner is taken in from the communicating toner container. In other words, when the toner is consumed in the developing process, the volume of the developer stored in the developer container is reduced, and the reduced amount of toner is supplied from the toner container to the developer container. In other words, the developer in the developer container holds the toner concentration.

  As an example of the developing device, in the technique disclosed in Japanese Patent Publication No. 5-67233, a magnetic particle layer is formed on a developing sleeve, and toner is supplied so as to come into contact with the magnetic particle layer in a toner supply unit in a container. A developer in which toner and magnetic particles are mixed by the toner supply unit taking in toner from the outer toner layer into the magnetic particle layer by movement of the magnetic particles in the magnetic particle layer accompanying rotation of the developing sleeve By regulating the layer thickness with a regulating member and transporting it to the developing unit, insufficient charging due to excessive supply of toner is prevented.

  In the technique disclosed in Japanese Patent Application Laid-Open No. 5-119625, in a developing sleeve rotating magnetic brush developing device having an internal magnetic pole, an insulating layer is provided on the surface of the developing sleeve and a toner supply roll is disposed near the developing sleeve. And an alternating voltage is applied between the toner supply roll and the developing sleeve to stabilize the toner concentration and toner charging.

  Further, in the technique disclosed in Japanese Patent Laid-Open No. 9-22178, magnetic toner is used as the toner constituting the developer, thereby stabilizing toner charging and preventing toner scattering. Further, in the technique disclosed in Japanese Patent Application Laid-Open No. 2000-352877, when the transport speed of the developer carrying member is the fastest, the toner concentration is not more than the limit toner concentration at which the surface of one carrier is completely covered. By configuring the toner concentration so as to achieve this, background contamination and toner scattering are prevented.

  Further, in the technique disclosed in Japanese Patent Application Laid-Open No. Hei 9-197833, the developer carrying member is more developed than the first regulating member that regulates the amount of developer carried and conveyed by the developer carrying member in the developer containing portion. By providing the second regulating member on the upstream side in the agent transport direction, the toner density adjustment is facilitated.

  However, in each of the above prior arts, the toner concentration is controlled by the change in the developer volume corresponding to the change in the toner concentration and the movement of the developer. The movement needs to be noticeable.

  Under such a demand, it is necessary to increase the developer density in the developer container around the developer carrier with a small amount of developer as compared with the normal two-component development method. The circulation is poor, and there are portions where the developer moves actively and portions where the movement of the developer is not active, so that the toner is not uniformly taken in. In addition, since the amount of developer is small, the absolute amount of toner contained in the developer is small, and because the developer density is high, the volume fluctuation of the developer is gradual even if the toner concentration is reduced, and the toner intake speed is increased. Due to the slowness, the toner is not sufficiently supplied onto the developer carrying member when continuously outputting high-density images with high toner consumption, and a desired density cannot be obtained.

  Furthermore, since the developer amount must be set small in advance, the stress applied to one magnetic carrier is increased and the life of the magnetic carrier is shortened. That is, the running cost increases and the response is slow, which causes a problem that the density of the high-density image cannot be secured.

  Therefore, the present applicant has already proposed a developing device as shown in FIG. 12 in order to solve the above problems (Japanese Patent Application No. 2003-280354).

  As shown in FIG. 12, a developing device 100 according to Japanese Patent Application No. 2003-280354 includes a magnetic field generating means 102 inside and a developer that carries and carries a two-component developer G containing toner and a magnetic carrier. A developer carrier 101, a developer container 103 for accommodating the two-component developer G adjacent to the developer carrier 101, and a part of the developer container 103 near the developer carrier 101. Adjacent to the developer carrying member 101, the developer agitating member 104 provided, a toner containing unit 105 that is provided in communication with the developer carrying member 101 via the developer containing unit 103, and that accommodates toner so as to be supplied. A developer retracting portion 106 that is provided downstream of the developer carrying member 101 in the developer transport direction with respect to the developer containing portion 103 and communicates with the developer containing portion 103, and the developer collecting portion. A part of the two-component developer G provided on the downstream side of the developer carrying member 101 in the developer carrying direction with respect to the portion 103 and the developer retracting unit 106 and carried and carried by the developer carrying member 101 is used as an excess developer. The two-component developer G separated into the developer retracting section 106 is provided with a developer separating means 107 for separating the surplus developer in the developer accommodating section 103 or the developer retracting section 106 according to the damming and toner density. Is configured to flow out to the developer accommodating portion 103.

  However, the conventional technique has the following problems. That is, in the case of the developing device 100 according to the above Japanese Patent Application No. 2003-280354, the developing device 100 and the image forming apparatus on which the developing device 100 is mounted in the horizontal direction due to an initial installation state, maintenance replacement, or a change in installation location. If the developer distribution is biased along the longitudinal direction of the developer accommodating portion 103 for some reason, such as being arranged in an inclined state with respect to the developer distribution unit 103, the developer distribution 100 is displaced in the longitudinal direction along with the bias of the developer distribution. A change in development density tends to appear along the structure.

  That is, in the developing device 100, as shown in FIG. 12, in addition to the tendency that a large amount of toner is supplied to a portion where the developer distribution is small along the axial direction of the stirring member 104, the stirring member 104 The developer G is hardly moved or exchanged along the axial direction. Therefore, in the developing device 100, when the developer distribution is biased, a difference in toner concentration occurs along the axial direction of the agitating member 104, and the developer G having the toner concentration difference remains as it is. As a result, it is conveyed to the carrier 103, and as a result, there is a problem that an image defect such as a gradient of image density occurs.

  To solve this problem, for example, Japanese Patent Application Laid-Open No. 61-212864 and Japanese Patent Application Laid-Open No. 2001-42615 can be used as techniques for making the developer distribution in the developing device appropriate and making the toner density distribution uniform. It is conceivable to apply the technique disclosed in Japanese Patent Laid-Open No. 2001-42616 or the like.

  As shown in FIG. 13, the developing device according to the above-mentioned Japanese Patent Application Laid-Open No. 61-212864 has an opening 110 through which developer G communicates, and stirring means provided with double augers 111 and 112 inside and outside. By transporting the developer G to one end side in the axial direction using 113, the developer density is circulated also in the axial direction to reduce the toner density difference.

  Further, in the developing devices according to the above-mentioned JP-A-2001-42615 and JP-A-2001-42616, as shown in FIG. 14, augers 121 and 122 having a reverse winding pitch inside and outside the stirring member 104 are provided. The developer is circulated by the agitating member 104 by providing the developer in the opposite directions and causing the developer to circulate, thereby reducing the deviation of the developer G and the toner density difference.

  However, in the case of the developing device disclosed in the above-mentioned JP-A-61-212864, JP-A-2001-42615, or JP-A-2001-42616, there is a certain amount of developer bias or toner density difference. Although the reduction can be achieved, it is necessary to use a stirring means having a complicated shape and structure, so that the structure is complicated and the cost of parts and manufacturing is excessive.

  Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and the object is to have a simple structure, which does not require parts and manufacturing costs, and is also developed. Even when the image forming apparatus and the image forming apparatus on which the developing device is mounted are inclined with respect to the horizontal direction, the deviation of the toner density is suppressed by autonomously correcting the deviation of the developer distribution. An object of the present invention is to provide a developing device capable of maintaining good image quality.

In order to solve the above-described problems, the invention described in claim 1 includes a developer carrying member that includes a magnetic field generating unit therein and conveys and carries a two-component developer including a toner and a magnetic carrier, A developer accommodating portion for accommodating a two-component developer adjacent to the developer bearing member; a developer agitating member disposed in a portion of the developer accommodating portion adjacent to the developer bearing member; and the developer accommodating portion. A toner container which is provided in communication with the developer carrier through which the toner is accommodated so that toner can be supplied; and adjacent to the developer carrier, the developer carrier is downstream in the developer transport direction with respect to the developer container. A developer retracting portion provided on a side of the developer containing portion and communicating with the developer accommodating portion; and a developer carrying member provided downstream of the developer accommodating portion with respect to the developer accommodating portion and the developer retracting portion. Of the two-component developer carried and conveyed by the body Damming the part as excess developer, and a developer separating means for separating the surplus developer in the developer accommodating portion or the developer saving unit according to the toner density,
In the developing device configured such that the two-component developer separated into the developer retracting portion flows out to the developer accommodating portion or the toner supply portion.
The developer stirring member has a plurality of blade portions arranged in parallel along the axial direction of the developer carrier, and is in the vicinity of the root of the blade portion and a hollow portion in the developer stirring member. The developing device is characterized in that openings communicating with each other are provided at least at both ends along the axial direction of the developer stirring member.

  Further, in the invention described in claim 2, the blade portion of the developer agitating member is inclined so that the upstream side along the rotation direction of the developer agitating member is located on the inner circumference and the downstream side is located on the outer circumference. The developing device according to claim 1, wherein the developing device is installed at an angle.

  Further, the invention described in claim 3 is characterized in that a protrusion-like member for loosening the developer introduced into the developer stirring member is provided in the developer stirring member. The developing device according to 1 or 2.

  The invention described in claim 4 is the developing device according to claim 3, wherein the protruding member provided on the developer stirring member is formed in a columnar shape or a conical shape. .

  Furthermore, the invention described in claim 5 is characterized in that the protruding members are provided so as to be scattered along the circumferential direction of the developer stirring member. It is a developing device.

  The invention described in claim 6 is characterized in that when the developer stirring member rotates, the blade portion of the developer stirring member and the protruding member have a relative speed difference. Item 6. The developing device according to any one of Items 3 to 5.

  Furthermore, in the invention described in claim 7, a plurality of partition members perpendicular to the axial direction of the developer stirring member are provided on the blade portion of the developer stirring member along the axial direction of the developer stirring member. The developing device according to claim 1, wherein

  According to the present invention, the structure is simple, the cost of parts and manufacturing is not required, and the developing device and the image forming apparatus on which the developing device is mounted are arranged to be inclined with respect to the horizontal direction. Even in such a case, it is possible to provide a developing device capable of maintaining a good image quality by autonomously correcting the deviation of the developer distribution and suppressing the fluctuation of the toner density.

  Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1
FIG. 2 shows an image forming apparatus to which the developing device according to Embodiment 1 of the present invention is applied.

  In FIG. 2, reference numeral 21 denotes an electrostatic latent image carrier made of an OPC photosensitive member that is rotationally driven along the direction of the arrow. The surface of the electrostatic latent image carrier 21 has a scorotron or a charging surface. It is charged by a charging device 22 such as a roll, and an electrostatic latent image is written by an exposure device 23 having a laser writing device or an LED array. This electrostatic latent image is formed as a potential image based on the contrast with a high potential portion not exposed to light because the surface potential of the electrostatic latent image carrier 21 exposed to light is lowered.

  The developing device 24 accommodates a two-component developer comprising a toner and a carrier is colored particles in the developing housing 31, it is supported with the two-component developer to the developer carrying member 32, the developer carrying member 32 a by applying a developing bias from a bias power source 25, to hold the developer carrying member 32 to an intermediate potential between the high potential portion and a low-potential portion of an electrostatic latent image, it is charged image portions of the electrostatic latent image The toner is developed with toner.

  Further, the transfer device 26 is constituted by, for example, a transfer roll disposed in contact with the electrostatic latent image carrier 21, and a transfer bias in a direction in which the toner image on the electrostatic latent image carrier 21 is attracted by the bias power source 27. Is applied so that the toner image on the electrostatic latent image carrier 21 is transferred to the recording material 28. The toner remaining on the electrostatic latent image carrier 21 is removed by, for example, a doctor blade type cleaning device 29.

  Further, the recording material 28 onto which the toner image is transferred from the electrostatic latent image carrier 21 is conveyed to a fixing device 50, and the toner image is fixed to the recording material 28 by the fixing device 50. The fixing device 50 includes a heat roll method for example, a heating roller 51 and the pressure roll 52, a recording material a toner image by passing the recording material 28 between the heating roll 51 and pressure roll 52 28 is fixed.

  FIG. 1 shows a developing apparatus according to Embodiment 1 of the present invention.

  The developing device includes a developer carrier having a magnetic field generating means therein and carrying and carrying a two-component developer containing toner and a magnetic carrier, and a two-component developer adjacent to the developer carrier. A developer accommodating portion to be accommodated; a developer agitating member disposed in a portion of the developer accommodating portion close to the developer carrying member; and a developer carrying member provided in communication with the developer accommodating portion. A toner storage unit that stores toner in a supplyable manner, and is provided adjacent to the developer carrier and downstream of the developer carrier in the developer transport direction with respect to the developer carrier, and communicates with the developer storage unit. A part of the two-component developer that is provided on the downstream side in the developer transport direction of the developer carrier relative to the developer retracting part and the developer accommodating part and the developer retracting part and is carried and transported by the developer carrier. Dampen as excess developer, toner And a developer separating means for separating the excess developer in the developer accommodating portion or the developer retracting portion according to the degree, and the two-component developer separated into the developer retracting portion is the developer accommodating portion or the toner. It is comprised so that it may flow out to a supply part.

  That is, as shown in FIG. 1, the developing device 24 includes a developing housing 31 having an opening at a position facing the electrostatic latent image carrier 21, and faces the opening of the developing housing 31. A developer carrying member 32 is disposed, and a developer containing portion 33 for containing the two-component developer G and a developer carrying member 32 are disposed in a portion of the developing housing 31 adjacent to the developer carrying member 32. Adjacent to the developer container 33 and communicated with the developer carrier 32 via the developer container 33 and a developer retracting part 34 provided downstream of the developer carrier 32 in the developer transport direction. In addition, a toner storage portion 35 that stores the toner T is formed.

  The two-component developer G is a developer composed of a toner T and a magnetic carrier. As the toner T, for example, a non-magnetic toner is used. If the magnetic property is different from that of the magnetic carrier, a magnetic toner is used. It may be used.

  The developer carrying member 32 includes a rotatable rotating sleeve 321 disposed on the outer periphery and a magnetic pole roll 322 disposed in a fixed state inside the rotating sleeve 321. The rotating sleeve 321 is formed in a thin cylindrical shape from nonmagnetic stainless steel or the like. In addition, the magnetic pole roll 322 has, for example, a conveyance magnetic pole (S2 in this example) aligned with the right side of the horizontal plane passing through the roll body center O, and the conveyance magnetic pole with respect to the rotation direction (counterclockwise) of the rotating sleeve 321. A conveying magnetic pole (N2 in this example) and a developing magnetic pole (S1 in this example) are arranged at an interval of approximately 30 ° from (S2) to the downstream side, while an approximately 30 ° interval from the conveying magnetic pole (S2) to the upstream side. The pickup magnetic pole (N1 in this example), the transport magnetic pole (S3 in this example), and the transport magnetic pole (N3 in this example) are arranged.

  As shown in FIG. 1, the developing magnetic pole (S1) faces the electrostatic latent image carrier 21, and the pickup magnetic pole (N1) captures the two-component developer G in the developer containing portion 33. However, the arrangement and number of the respective magnetic poles may be appropriately selected, while the rotating sleeve 321 rotates counterclockwise and the developing magnetic pole (S1) of the magnetic pole roll 322 is provided. In the developing unit, it faces the electrostatic latent image carrier 21.

  Further, the developer accommodating portion 33 has a space for accommodating the two-component developer G, and a developer agitating member in a portion of the developer accommodating portion 33 that is close to (or in contact with) the developer carrier 32. 36 is rotatably arranged along the clockwise direction. Further, the bottom shape of the developer container 33 has a curved shape along the developer carrier 32 and the developer agitating member 36, and a predetermined interval is provided between the developer carrier 32 and the developer agitating member 36. The developer transport path is secured.

  Further, as the developer stirring member 36, a member having a special configuration is used as will be described later. The two-component developer G stirred by the developer stirring member 36 is captured in the vicinity of the pickup magnetic pole (N1) of the developer carrier 32 and is carried and conveyed by the rotation of the rotating sleeve 321 of the developer carrier 32. It has become.

  Further, as shown in FIG. 1, the toner storage portion 35 has a toner stirring member 351 for stirring and transporting the stored toner T. The toner stirring member 351 is, for example, attached to the rotating body 352. An elastic film 353 is attached, and the toner T is swept out along the bottom wall surface of the toner storage portion 35. Further, the bottom shape of the toner accommodating portion 35 has a curved shape along the movement rotation locus of the toner agitating member 351, and the connecting portion between the developer accommodating portion 33 and the toner accommodating portion 35 is provided with toner. A supply port 37 is provided, and the lower end edge of the toner supply port 37 is set slightly higher than the center position of the toner stirring member 351. On the other hand, a protrusion 38 is formed at the upper edge of the toner supply port 37 so as to protrude from the upper edge toward the developer stirring member 36. The protrusion 38 extends from the toner container 35. A passage for guiding the toner T to the developer accommodating portion 33 is formed.

  In this embodiment, the developer accommodating portion 33 and the developer retracting portion 34 are separated by the developer separating member 39. For example, as shown in FIG. 3, the developer separating member 39 is a plate-like member formed with a width substantially the same as that of the developer carrier 32. The developer separating member 39 is composed of a developer carrier. It is inclined and arranged obliquely downward so that the 32 side is the upper side and the opposite side is the lower side. The developer separating member 39 includes an inclined portion 391 disposed in an inclined state, and a lower end portion 392 integrally formed on the lower end portion of the inclined portion 391 downward in the vertical direction. . The upper end 393 of the developer separating member 39 located on the developer carrier 32 side is directly above the carrier magnetic pole (N2) in the developer carrier 32 or the carrier magnetic pole (N2) as shown in FIG. ) To the upstream side of the developer conveyance direction (clockwise direction side), the surface of the developer carrying member 32 is opposed at a position of several hundred μm to several mm. On the other hand, a lower end 394 opposite to the upper end 393 protrudes downward in the vertical direction in the vicinity of the protrusion 38 described above. Note that the inclination angle of the inclined portion 391 may be arbitrarily set. Further, the end surface of the upper end 393 of the developer separating member 39 is formed to have an end surface along the horizontal direction H0, and the end surface of the lower end 394 is inclined substantially parallel to the left side surface of the protruding portion 38. It is formed to have an end face.

  Further, between the lower end portion 392 and the protruding portion 38 of the developer separating member 39 and between the upper end 393 of the developer separating member 39 and the developer carrier 32, the developer retracting portion 34 and the developer accommodating portion are provided. A circulation path 40 communicating with the portion 33 is formed. In this circulation path 40, for example, the two-component developer G in the developer accommodating portion 33 flows into the developer retracting portion 34 from the inclined portion 391 side, and the inflowed two-component developer G is developed from the lower end portion 392 side. This is a path that flows out to the medicine container 33.

  Further, in this embodiment, the conveyance magnetic pole (N2) and the development magnetic pole (S1) are located at the downstream side (counterclockwise direction side) in the developer conveyance direction from the conveyance magnetic pole (N2) in the developer carrier 32. Between them, a damming portion 41 is disposed so as to face the developer carrier 32. This damming portion 41 has substantially the same width as the developer carrier 32, one end is supported by the development housing 31, and the tip end is connected to the developer carrier 32 with a gap of about several tens to several hundreds of μm. It is close.

  In this embodiment, since a large amount of the two-component developer G is supplied to the damming portion 41, the gap between the upper end portion 39b of the developer separating member 39 and the developer carrier 32 is different from that of the damming portion 41. It is set wider than the gap with the developer carrier 32.

  In this embodiment, the damming portion 41 also functions as a layer thickness regulating function that regulates the layer thickness of the two-component developer G carried and conveyed by the developer carrier 32. What is the layer thickness regulating function? You may make another. In this case, for example, a mode in which the layer thickness regulating member 42 is provided between the damming portion 41 and the developing magnetic pole (Sl) can be mentioned.

  By the way, in this embodiment, the developer stirring member has a plurality of blade portions arranged in parallel along the axial direction of the developer carrier, and is near the root of the blade portion, and Openings communicating with the hollow portion in the developer stirring member are configured to be provided at at least both end portions along the axial direction of the developer stirring member.

  That is, in the developing device according to this embodiment, as shown in FIG. 1, the developer stirring member 36 disposed in the developer containing portion 33 is replaced with the developer as shown in FIGS. A plurality of (six in the illustrated example) blade portions 361 are arranged in parallel along the axial direction of the carrier 32. As shown in FIG. 6, the plurality of blade portions 361 are formed in a thin flat plate shape, and a developer is formed with respect to an arc set concentrically around the rotation shaft 362 of the developer stirring member 36. The agitating member 36 is installed in an inclined state with the same inclination angle θ such that the upstream side along the rotation direction is located on the inner circumference and the downstream side is located on the outer circumference. The plurality of blade portions 361 are arranged at equal angles along the circumferential direction of the developer stirring member 36, and the inner peripheral end 361a of the blade portion 361 abuts near the middle of the adjacent blade portions. These are arranged so that there is no gap between them. Furthermore, a hexagonal mounting plate 363 for mounting the plurality of blade portions in a fixed state is disposed at both axial ends of the plurality of blade portions 361, and the mounting plate 363 has a rotational axis. The inside 364 of the developer stirring member 36 is hollow.

  Further, as shown in FIGS. 5 and 6, the developer agitating member 36 communicates with the hollow portion 364 in the vicinity of the root (inner peripheral end) of each blade portion 361 and in the developer agitating member 36. Opening portions 365 are provided at both end portions along the axial direction of the developer stirring member 36 over a predetermined length. The opening 365 provided in the vicinity of the root of each blade 361 is disposed in a state where the developing device 24 is inclined, and the two-component developer G in the developer containing portion 33 extends along the longitudinal direction of the developing device 24. When the bias occurs, the lower side of the developing device 24, that is, the side where the amount of the two-component developer G in the developer containing portion 33 is increased, and the higher side of the developing device 24, that is, the developer containing portion 33. Due to the pressure difference of the two-component developer G from the side where the amount of the two-component developer G is reduced, the two-component developer G is removed from the side where the amount of the two-component developer G is large and the pressure is increased. This is for generating a transport force for transporting toward the side where the amount of the two-component developer G is small and the pressure is low.

  The length and the opening width of the opening 365 of the developer stirring member 36 are appropriately set so as to effectively generate the developer G conveying action.

  In the above configuration, the developing device according to this embodiment has a simple structure as described below, does not require parts and manufacturing costs, and is equipped with the developing device and the developing device. Even when the image forming apparatus is arranged with an inclination with respect to the horizontal direction, it is possible to maintain a good image quality by autonomously correcting the deviation of the developer distribution and suppressing the fluctuation of the toner density. It has become.

  That is, in the developing device 24 according to this embodiment, as shown in FIG. 1, the two-component developer G accommodated in the developer accommodating portion 33 is agitated by the developer agitating member 36, and the developer carrier 32. It is captured by the pickup magnetic pole (Nl) inside. After that, the captured two-component developer G is separated from the developer carrier 32 (rotating sleeve 321) by the magnetic attraction force of the pickup magnetic pole (N1) and the transport magnetic pole (S2) and the frictional force between the surface of the developer carrier 32. ) In the rotation direction. The transported two-component developer G, when it reaches the vicinity of the stop part 41, to form the bristles by the conveying pole (N2). Further, the rising of the two-component developer G is regulated by the damming portion 41, so that the developer layer is formed on the developer carrier 32, and the developer layer is formed on the electrostatic latent image carrier. 21 is conveyed to a developing area facing 21. Further, the developer layer of the two-component developer G transported to the development area forms a magnetic brush by the magnetic attraction force of the developing magnetic pole (S1), and the toner T in the two-component developer G forming this magnetic brush is The electrostatic latent image on the electrostatic latent image carrier 21 is visualized by a developing electric field formed between the electrostatic latent image carrier 21 and the developer carrier 32.

  Next, the behavior of the two-component developer G in the vicinity of the damming portion 41 will be described.

  First, in FIG. 1, it is assumed that the toner density of the two-component developer G carried and conveyed by the developer carrier 32 is low. Since the two-component developer G has a small amount of toner covering the surface of the magnetic carrier, a relatively large surface of the magnetic carrier is exposed.

  That is, since the large magnetic attraction force experienced by the two-component developer G from (N2 in this example) the external magnetic field, the two-component developer G low toner concentration is reliably conveyed to the vicinity of stop part 41. The two-component developer G reliably transported to the damming portion 41 pushes out the staying developer staying in the vicinity of the damming portion 41 by the damming force of the damming portion 41 and the magnetic restraining force of the conveying magnetic pole (N2). As shown in FIG. 7, the pushed-out staying developer becomes a falling developer and falls onto the developer separation member 39, passes through the developer retracting portion 34, and then returns to the developer accommodating portion 33 again. .

  At this time, when the two-component developer G having a low toner concentration is led to the developer retracting portion 34 as described above, a space is made in the developer accommodating portion 33 accordingly. As a result, the two-component developer G that has been in the toner supply path 43 from the toner supply port 37 to the developer accommodating portion 33 is caused by the conveying force of the developer agitating member 36 and the weight of the two-component developer G. Get quickly into the space. As a result, the toner supply port 37 receives the toner T from the toner storage unit 35, and the toner T is quickly supplied to the developer storage unit 33 via the toner supply path 43.

  On the other hand, assuming that the toner density of the two-component developer G carried and conveyed by the developer carrier 32 is high, the two-component developer G has a large amount of toner covering the surface of the magnetic carrier. There is little surface exposure of the magnetic carrier. That is, since the magnetic attractive force received by the two-component developer G from the external magnetic field (N2 in this example) is small, most of the two-component developer G having a high toner concentration is developed with respect to the rotation direction of the developer carrier 32. It will fall at a position upstream of the tip of the agent separating member 39. As a result, the two-component developer G does not reach the staying developer staying in the vicinity of the damming portion 41 and does not fall on the developer separating member 39.

  Therefore, the two-component developer G does not fall on the developer separation member 39 but falls at a position upstream of the upper end portion 39b of the developer separation member 39 with respect to the rotation direction of the developer carrier 32. Then, the process returns directly to the developer container 33. At this time, unlike the case where the toner concentration is low, the toner supply port 37 is blocked by the two-component developer G without creating a space in the developer accommodating portion 33, so that the toner The toner T is not supplied from the storage unit 35.

  As described above, the toner replenishment mechanism according to the present embodiment uses the change in magnetic attraction force in addition to the change in fluidity and bulk of the two-component developer G according to the toner concentration. The toner is supplied to the low two-component developer G, and the toner is not supplied to the two-component developer G having a high toner concentration. When the toner density is low, the two-component developer G is temporarily guided to the developer retracting portion 34, and the bulk change of the two-component developer G in the developer containing portion 33 is emphasized. Accordingly, the two-component developer G in the developer container 33 can quickly take in the toner T in the toner container 35, and can cope with continuous output of high-density images.

  By the way, the developing device 24 according to this embodiment is used with the image forming apparatus on which the developing device 24 is mounted being inclined along the longitudinal direction of the developing device 24 with respect to the horizontal direction. There is a case. Then, the two-component developer G in the developing device 24 is also accommodated in the developer accommodating portion 33 in a state of being inclined with the inclination of the image forming apparatus.

  Now, in FIG. 1, consider a case where the front side of the developing device 24 is high and the back side of the developing device 24 is low. When the toner concentration in the developer accommodating portion 33 decreases, the two-component developer G flows on the developer separating member 39 and falls into the developer accommodating portion 33. In this case, the two-component developer G flowing on the developer separating member 39 is biased to the relatively low back side of the developing device 24.

  At that time, as shown in FIG. 1, a developer agitating member is rotatably disposed inside the developer accommodating portion of the developing device 24, and the developer agitating member is accommodated in the developer accommodating portion. The component developer G is conveyed to the developer carrying member while being stirred by the developer stirring member, and is used in the developing process.

  In the state where the developing device is installed horizontally, the developer agitating member stirs the two-component developer G along with the rotation of the developer agitating member. It occurs only along the circumferential direction of the developer stirring member, and the stirring and conveying action along the axial direction of the developer stirring member does not occur.

  On the other hand, the developer agitating member is agitated along with the rotation of the developer agitating member in a state where the developing device is installed to be inclined along the longitudinal direction of the developing device with respect to the horizontal direction. The two-component developer G is conveyed from the side where the amount of the two-component developer G is large and the pressure is increased toward the side where the amount of the two-component developer G is small and the pressure is low. Become.

  The reason is that the developer agitating member has openings at both ends in the axial direction, and therefore the two-component developer G located near both ends in the axial direction of the developer agitating member is: It flows into the inside of the developer stirring member formed in a hollow shape through the opening, and the inside of the developer stirring member is filled with the two-component developer G.

  In this state, when the developer stirring member is rotated in the counterclockwise direction in FIG. 6, the two-component development from the opening is started from the side where the pressure of the two-component developer G of the developer stirring member is increased. Although the agent G continues to flow in, the two-component developer G hardly flows from the side of the developer stirring member where the pressure of the two-component developer G is low due to the pressure difference with the other end. As a result, as a result of the lowering of the developing device, the two-component developer G continues to flow into the hollow portion in the developer stirring member from the side where the pressure of the two-component developer G increases, and this developer stirring member The two-component developer G that has flowed into the hollow portion is gradually conveyed to the low pressure side due to the pressure difference from the low pressure side, and is discharged into the developer containing portion from the opening on the low pressure side. Will be.

  Thus, in the developing device 24 according to the above-described embodiment, even when the developing device 24 is used in an inclined state, the developer stirring member 36 configured as shown in FIGS. 5 and 6 is used. The two-component developer G is conveyed while being stirred from the side where the two-component developer G is present in the developer accommodating portion 33 to the end portion where the two-component developer G is small. Even if the image forming apparatus on which the developing device is mounted is inclined with respect to the horizontal direction, the structure is simple, the cost of parts and manufacturing is not required, and the developing device is mounted. In addition, it is possible to maintain a good image quality by autonomously correcting the deviation of the developer distribution and suppressing the fluctuation of the toner density.

Embodiment 2
FIG. 8 shows a second embodiment of the present invention. The same parts as those in the first embodiment will be described with the same reference numerals. In the second embodiment, the inside of the developer agitating member is shown in FIG. In this configuration, a protruding member for loosening the developer introduced into the developer stirring member is provided.

  In the second embodiment, the protruding member provided on the developer stirring member is formed in a columnar shape or a conical shape.

  Furthermore, in the second embodiment, the protruding members are provided so as to be scattered along the circumferential direction of the developer stirring member.

  In the second embodiment, when the developer stirring member rotates, the blade portion of the developer stirring member and the protruding member have a relative speed difference.

  That is, in the second embodiment, as shown in FIG. 8, a protruding member 42 for loosening a lump of the developer G introduced into the developer stirring member 36 is provided inside the developer stirring member 36. It has been. The protruding member 42 is formed in a conical shape having a sharp tip, and a plurality of protruding members 42 are provided at regular intervals along the circumferential direction with the outer periphery of the hollow shaft 43 facing radially outward. The protruding member 42 may be formed in a thin cylindrical shape. The protruding member 42 is provided at a position corresponding to the opening 365 of the developer agitating member 36, and collects the developer G introduced into the developer agitating member 36 from the opening 365. It is supposed to be crushed. The protruding member 42 may be provided over the entire length of the hollow shaft 43 as long as it does not adversely affect the transportability of the developer G. Further, the hollow shaft 43 on which the protruding member 42 is formed is disposed in a state of being fixed to the developing housing 31 of the developing device 24, and is relative to the blade portion 361 of the developer stirring member 36 that is rotationally driven. It is configured to have a typical speed difference.

  According to the second embodiment, the two-component developer G aggregated in the developer accommodating portion 33 is introduced into the interior from the opening 365 of the developer agitating member 36 due to the pressure in the developer accommodating portion 33. Even in this case, it is loosened by the plurality of protruding members 42 provided in the developer stirring member 36, and the fluidity is increased.

  Therefore, as described in the first embodiment, the two-component developer G is transported from the side where the amount of the two-component developer G is large to the side where the amount of the two-component developer G is small due to the transport action of the developer stirring member 36. It is possible to maintain good image quality by correcting the bias autonomously and suppressing fluctuations in toner density.

  Since other configurations and operations are the same as those of the first embodiment, description thereof is omitted.

Embodiment 3
FIG. 9 shows a third embodiment of the present invention. The same reference numerals are given to the same parts as those in the first embodiment. In the third embodiment, the developer agitating member is shown in FIG. A plurality of partition members orthogonal to the axial direction of the developer stirring member are provided on the blade portion along the axial direction of the developer stirring member.

  That is, in the third embodiment, as shown in FIGS. 9 and 10, the blade portion 361 of the developer stirring member 36 is provided with a plurality of partition members 44 that are orthogonal to the axial direction of the developer stirring member 36. The plurality of partition members 44 are formed integrally with the developer agitating member 36 and are provided so as to be orthogonal to the longitudinal direction of the developer carrier 32. As the partition member 44, one formed in a triangular shape as shown in FIG. 10 or one formed in a fan shape as shown in FIG. 11 is used. In consideration of the effect of preventing the movement of the two-component developer G, it is preferable that the partition member 44 is formed in a fan shape having a large area. However, the shape and number of the partition members 44 and the space between the partition members 44 are not limited. The pitch can be arbitrarily set.

  As described above, according to the third embodiment, even when the front side of the developing device 24 is high and the back side of the developing device 24 is set low, the developer carrying member is being stirred while being stirred by the developer stirring member 36. The two-component developer G supplied to the body 32 tends to move obliquely, but is blocked by the partition member 44 provided in the developer stirring member 36 and moves in a biased manner over the interval of the partition member 44. To be prevented.

  Therefore, in the developing device 24, even when the developing device 24 is disposed in a state of being inclined along the longitudinal direction, the two-component developer G is not allowed to move toward the one end side of the developing device 24. In combination with the conveying action of the developer stirring member 36 described in the first embodiment, the toner concentration in the two-component developer G can be made more constant along the longitudinal direction of the developing device 24. Can be maintained.

  Since other configurations and operations are the same as those of the first embodiment, description thereof is omitted.

1 is a block diagram showing a developing device according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing an image forming apparatus to which the developing device according to Embodiment 1 of the present invention is applied. FIG. 3 is a perspective view showing the developer separating member. FIG. 4 is an enlarged configuration diagram showing the vicinity of the developer carrying member and the developer separating member. FIG. 5 is a perspective configuration diagram showing the developer stirring member. FIG. 6 is a cross-sectional configuration diagram illustrating the developer stirring member. FIG. 7 is a schematic view showing the movement of the developer in the vicinity of the damming portion. FIG. 8 is a sectional view showing a developer stirring member of a developing device according to Embodiment 2 of the present invention. FIG. 9 is a block diagram showing a developing device according to Embodiment 3 of the present invention. FIG. 10 is a perspective configuration diagram showing the developer stirring member. FIG. 11 is a perspective configuration diagram illustrating the developer stirring member. FIG. 12 is a block diagram showing a conventional developing device. FIG. 13 is a block diagram showing another conventional developing apparatus. FIG. 14 is a block diagram showing a conventional developer stirring member.

Explanation of symbols

  24: developing device, 32: developer carrier, 33: developer accommodating portion, 34: developer retracting portion, 35: toner accommodating portion, 36: developer stirring member, 361: blade portion, 365: opening portion, 39 : Developer separating member (developer separating means), 42: protruding member, G: two-component developer.

Claims (7)

A developer carrying body having a magnetic field generating means therein and carrying and carrying a two-component developer containing toner and magnetic carrier, and a developer containing a two-component developer adjacent to the developer carrying body A developer agitating member disposed in a portion of the developer accommodating portion adjacent to the developer carrying member, and a developer carrying member provided through the developer containing portion to supply toner. A toner accommodating portion to be accommodated, and a developer retracting portion which is provided on the downstream side in the developer transport direction of the developer bearing member with respect to the developer accommodating portion adjacent to the developer bearing member and communicates with the developer accommodating portion. A part of the two-component developer that is provided downstream of the developer carrying member in the developer carrying direction with respect to the developer containing portion and the developer retracting portion and carried by the developer carrying member is used as an excess developer. Development based on coughing and toner density Accommodating portion or a developer separating means for separating the surplus developer to the developer saving unit,
In the developing device configured such that the two-component developer separated into the developer retracting portion flows out to the developer accommodating portion or the toner supply portion.
The developer stirring member has a plurality of blade portions arranged in parallel along the axial direction of the developer carrier, and is in the vicinity of the root of the blade portion and a hollow portion in the developer stirring member. A developing device comprising openings at least at both ends along the axial direction of the developer stirring member. The blade portion of the developer agitating member is installed with an inclination angle so that the upstream side along the rotation direction of the developer agitating member is located on the inner periphery and the downstream side is located on the outer periphery. The developing device according to claim 1. The developing device according to claim 1, wherein a protrusion-like member for loosening a developer introduced into the developer agitating member is provided inside the developer agitating member. 4. The developing device according to claim 3, wherein the protruding member provided on the developer stirring member is formed in a columnar shape or a conical shape. The developing device according to claim 3, wherein the protruding members are provided so as to be scattered along a circumferential direction of the developer stirring member. 6. The developing device according to claim 3, wherein when the developer stirring member rotates, a blade portion of the developer stirring member and a protruding member have a relative speed difference. . The blade portion of the developer agitating member is provided with a plurality of partition members orthogonal to the axial direction of the developer agitating member along the axial direction of the developer agitating member. The developing device according to any one of the above.

Images