JP2008276089A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device using two-component developer, which achieves high-quality image formation over a long term by suppressing toner deterioration and carrier deterioration, and to provide an image forming apparatus. <P>SOLUTION: The developing device is equipped with a partition member arranged proximately to a developer carrier and partitioning between the developer carrier and space on a side to supply the developer to the developer carrier, and an opening/closing member controlling the supply amount of developer to the developer carrier by opening/closing a developer supply path to the developer carrier from the space partitioned by the partition member. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, or a multifunction machine using the electrophotographic system, and a developing device used therefor. In particular, the present invention relates to a developing device and an image forming apparatus that use a two-component developer composed of a carrier and a toner to develop an electrostatic latent image.

  Conventionally, in an image forming apparatus using an electrophotographic method, as a developing method of an electrostatic latent image formed on an image carrier, a one-component developing method using only toner as a developer and a two-component using a toner and a carrier Development methods are known.

  In the one-component development system, the toner is generally charged by passing the toner through a regulating portion formed by a toner carrier and a regulation plate pressed against the toner carrier, and a desired toner thin layer is formed. Develop the electrostatic latent image. The one-component development method does not cause image unevenness due to the magnetic brush, and has excellent dot reproducibility and image uniformity, does not cause carrier consumption to the image carrier, simplifies the device, reduces size, and reduces costs It is advantageous in terms of However, on the other hand, the toner is easily deteriorated by the strong stress of the restricting portion, and the charge acceptability of the toner tends to be lowered. Further, the toner regulating member and the surface of the toner carrying member are contaminated with the toner and the external additive, so that the charge imparting property to the toner is lowered and causes problems such as fogging. As a result, the life of the developing device is shortened. End up. Compared to such a one-component development method, in the two-component development method, the toner is charged by frictional charging by mixing with the carrier, so that the stress is small and it is advantageous for the deterioration of the toner. Further, since the carrier as a charge imparting member to the toner has a large surface area, it is relatively resistant to contamination by the toner and external additives, and is advantageous in terms of extending the life of the developer.

  However, even in the two-component development method, it is necessary to form a developer layer on the magnet roller, and stress is applied to the developer at the layer thickness regulating portion that forms the developer layer. This is a stress generated when the developer carried and conveyed on the surface of the magnet roller by the magnetic force is scraped off by the layer thickness regulating member. Although this stress is small as compared with the restriction part of the one-component development system, it cannot be said that the stress is sufficiently small because the developer that generates cohesive force by the magnetic force is forcibly worn out. In fact, even in the two-component development system, when printing with a small image area ratio is performed continuously, this stress is the main factor, causing external additives to be buried in the toner surface, toner cracking, etc. cause. Further, when the carrier is used for a long period of time, the carrier deteriorates due to wear of the surface coat resin of the carrier or adhesion of toner fine powder or external additives. Such deterioration of the developer causes a decrease in toner charge amount, generation of reverse polarity toner, generation of uncharged toner, and the like, and fogging of the background portion and dirt due to dusty toner appear as image defects. As described above, even with the two-component development method, problems due to the stress on the developer remain, and further reduction in stress is desired in order to extend the life of the developer.

  As a method for extending the life of a two-component developer, Patent Document 1 discloses that a carrier is supplied by supplying a small amount of carrier together with toner or by itself and discharging a deteriorated developer having reduced chargeability accordingly. Has been disclosed to suppress the increase in the deteriorated carrier ratio. In this apparatus, since the carrier is replaced, it is possible to suppress a decrease in toner charge amount due to carrier deterioration at a certain level, which is advantageous in extending the service life.

  Further, Patent Document 2 discloses a developing device having a concept of delivering a developer whose amount is already regulated to a developer carrying member. A second Mag roller for developing the image carrier and a first Mag roller for supplying the developer to the second Mag roller are provided, and the developer is quantified by the developer layer thickness regulating member on the first Mag roller. The developer is transferred to the second Mag roll.

Further, in Patent Document 3, a supply roller having a plurality of recesses arranged around is provided as a member for supplying a constant amount of developer to the developing roller, and the developer roller scoops up the developer scooped by the supply roller with a magnetic force. A method of adsorbing by the above has been proposed. By using this method, a regulating member that regulates the layer thickness of the developer on the developing roller becomes unnecessary, and stress on the developer can be reduced.
JP 59-1000047 A JP 2007-3851 A JP 2001-125366 A

  However, in Patent Document 1, there is a problem in terms of cost, environment, and the like because a mechanism for collecting the discharged carrier is necessary and the carrier becomes a consumable item. In addition, it is necessary to repeat a predetermined amount of printing until the new / old ratio of the carrier is stabilized, and there is a problem that the initial image characteristics change. Further, in this configuration, although a certain effect can be obtained with respect to carrier deterioration, no effect is obtained with respect to toner deterioration as compared with the conventional case, and printing with a small image portion ratio is continuously performed. In such a case, there is a problem that the toner is deteriorated and the image quality is lowered. In the configuration of Patent Document 2, the developer that is restrained by the magnetic force on the first Mag roll is controlled by the regulating member, and the carrier deterioration and toner are caused by the stress applied to the developer. The problem of deterioration arises. Further, in the configuration of Patent Document 3, when the flowability of the developer in the developer tank changes due to environmental changes or the like, the amount of developer scooped by the supply member changes, and a stable developer layer is formed on the developer carrier. There is a problem that it cannot be formed. Further, when used in a high-speed image forming apparatus, there is a problem that the developer scooped up by the supply member is detached from the supply member by a centrifugal force and cannot be stably supplied, and can only be used in a low-speed image forming apparatus. Furthermore, since the developer is scooped up from the developer tank, it is necessary that the developer in the developer tank comes below the upper part of the supply member. For this reason, the freedom degree of arrangement | positioning of a developing device is restrict | limited and an apparatus becomes large sized.

  An object of the present invention is to provide a developing device and an image forming apparatus capable of suppressing toner deterioration and carrier deterioration and realizing high-quality image formation over a long period of time.

  In order to solve the above problems, the present invention has the following features.

1.
In a developing device including a developer carrying member that carries and conveys a developer containing toner and a carrier on the surface by magnetic force,
A partition member disposed in the vicinity of the developer carrier, and partitioning the developer carrier and a space on the side where the developer is supplied to the developer carrier;
An opening / closing member that controls the amount of developer supplied to the developer carrier by opening and closing a developer supply path from the space partitioned by the partition member to the developer carrier. Developing device.

2.
2. The developing device according to 1, wherein the developer carrying member is a magnet roller having a magnetic pole therein.

3.
3. The developing device according to 2, wherein the magnet roller has a homopolar magnetized portion so that the developer conveyed by the magnet roller is separated from the partition member on the upstream side in the developer conveying direction. .

4).
The opening / closing member is a valve having one end fixed and a free end that can be swung at the other end, and swings the valve to control the supply of the developer from the developer tank to the developer carrier. The developing device according to any one of claims 1 to 3, further comprising an opening / closing control member.

5.
5. The developing device according to claim 4, wherein the opening / closing control member is a rotating body having a polygonal cross section.

6).
5. The developing device according to claim 4, wherein the opening / closing control member is a rotating body having a cross section of a circular arc and a straight line.

7).
The developing device according to any one of claims 1 to 3, wherein the opening / closing member is a shutter member that controls a communication state between the developer carrying member and the developer tank by moving in parallel.

8).
The developing device according to any one of claims 1 to 3, wherein the opening / closing member is a rotary body having a polygonal cross section for switching a communication state by rotation.

9.
1. The device according to claim 1, further comprising a toner carrier that is disposed to face the developer carrier, separates the toner from the developer on the developer carrier, and carries the toner on the surface. The developing device according to 1.

10.
An image carrier, means for forming an electrostatic latent image on the image carrier, and the developing device according to any one of 1 to 9 for developing the electrostatic latent image on the image carrier. An image forming apparatus comprising:

  According to the developing device of the present invention, the partition member that is disposed in the vicinity of the image carrier and partitions the developer carrier and the space on the developer supply side with respect to the developer carrier, and the partition member An opening / closing member that controls the amount of the developer supplied to the developer carrier by opening and closing the developer supply path to the developer carrier from the partitioned space is provided. By adopting such a configuration, the opening / closing member can be intermittently controlled, and a predetermined amount of developer can be stably supplied to the developer carrying member. Therefore, it is not necessary to regulate the layer thickness on the developer carrying member in a state where the developer is subjected to the magnetic binding force as in the conventional case, the stress applied to the carrier and toner is reduced, and carrier deterioration and toner deterioration are suppressed. be able to. As a result, it is possible to provide a developing device having excellent image stability and a long life, and an image forming apparatus using the developing device.

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

  FIG. 1 shows a main part of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus is a printer that performs image formation by transferring a toner image formed on an image carrier (photoconductor) 1 to a transfer medium P such as paper by an electrophotographic method. This image forming apparatus has an image carrier 1 for carrying an image, and a charging member 3 as a charging unit for charging the image carrier 1 and an image carrier around the image carrier 1. A developing device 2a for developing the electrostatic latent image on the image 1, a transfer roller 4 for transferring the toner image on the image carrier 1, and a cleaning blade 5 for removing residual toner on the image carrier 1 It arranges in order along the rotation direction A of the body 1.

  The image carrier 1 is charged by the charging member 3 and then exposed by an exposure device equipped with a laser emitter or the like at the position E in the figure, and an electrostatic latent image is formed on the surface thereof. The developing device 2a develops the electrostatic latent image into a toner image. The transfer roller 4 transfers the toner image on the image carrier 1 to the transfer medium P, and then discharges it in the direction of arrow C in the figure. The cleaning blade 5 removes the residual toner on the image carrier 1 after the transfer with its mechanical force. The image carrier 1, the charging member 3, the exposure device, the transfer roller 4, the cleaning blade 5 and the like used in the image forming apparatus may arbitrarily use a known electrophotographic technique. For example, although a charging roller is shown in the drawing as the charging means, a charging device that is not in contact with the image carrier 1 may be used. Further, for example, there may be no cleaning blade.

  In the present embodiment, the developing device 2 a carries a developer tank 24 containing the developer 23, the developer 23 supplied from the developer tank 24 in the developer taking-in area 7 on the surface, and transported to the developing area 6. The developer carrying member 11 is provided, and the developer after passing through the developing region 6 is separated in the developer separating region 8 and returned to the developer tank 24.

  The developer 23 includes toner and a carrier for charging the toner.

  The toner is not particularly limited, and a commonly used known toner can be used. The binder resin contains a colorant or, if necessary, a charge control agent or a release agent, and is added externally. What processed the agent can be used. The toner particle diameter is not limited to this, but is preferably about 3 to 15 μm.

  In manufacturing such a toner, it can be manufactured by a publicly known method, for example, a pulverization method, an emulsion polymerization method, a suspension polymerization method, or the like.

  The binder resin used in the toner is not limited to this. For example, styrene resin (monopolymer or copolymer containing styrene or a styrene-substituted product), polyester resin, epoxy resin, vinyl chloride Resins, phenol resins, polyethylene resins, polypropylene resins, polyurethane resins, silicone resins and the like can be mentioned. It is preferable to use those having a softening temperature in the range of 80 to 160 ° C. and those having a glass transition point in the range of 50 to 75 ° C., depending on the resin alone or the composite.

  Moreover, as a coloring agent, the publicly known well-known thing can be used, for example, carbon black, aniline black, activated carbon, magnetite, benzine yellow, permanent yellow, naphthol yellow, phthalocyanine blue, first sky blue, ultra Marine blue, rose bengal, lake red, or the like can be used, and it is generally preferable to use 2 to 20 parts by mass with respect to 100 parts by mass of the binder resin.

  As the charge control agent, known ones can be used. Examples of the charge control agent for positively chargeable toners include nigrosine dyes, quaternary ammonium salt compounds, triphenylmethane compounds, imidazoles. System compounds and polyamine resins. Examples of the charge control agent for negatively chargeable toners include metal-containing azo dyes such as Cr, Co, Al, and Fe, salicylic acid metal compounds, alkyl salicylic acid metal compounds, and curlyx arene compounds. In general, the charge control agent is preferably used at a ratio of 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

  In addition, as the above-mentioned mold release agent, known ones that are generally used can be used. For example, polyethylene, polypropylene, carnauba wax, sazol wax and the like can be used alone or in combination of two or more. In general, it is preferably used at a ratio of 0.1 to 10 parts by mass with respect to 100 parts by mass of the binder resin.

  Also, as the above external additives, publicly known ones can be used, and fluidity improvement, for example, inorganic fine particles such as silica, titanium oxide, aluminum oxide, acrylic resin, styrene resin, silicone resin In addition, resin fine particles such as a fluororesin can be used, and it is particularly preferable to use one that has been hydrophobized with a silane coupling agent, a titanium coupling agent, silicone oil or the like. Such a fluidizing agent is added at a ratio of 0.1 to 5 parts by mass with respect to 100 parts by mass of the toner. The number average primary particle size of the external additive is preferably 10 to 100 nm.

  Further, as the external additive, particles having a chargeability opposite to that of the toner may be used. The reverse polarity particles preferably used are appropriately selected depending on the charging polarity of the toner. When a negatively chargeable toner is used as the toner, fine particles having positive chargeability are used as the reverse polarity particles. For example, inorganic fine particles such as strontium titanate, barium titanate, and alumina, acrylic resin, benzoguanamine resin, and nylon resin are used. Fine particles composed of thermoplastic resin such as polyimide resin and polyamide resin or thermosetting resin can be used, and a positive charge control agent imparting positive charge property can be contained in the resin, or a nitrogen-containing monomer You may make it comprise the copolymer of these. Here, as said positive charge control agent, nigrosine dye, a quaternary ammonium salt, etc. can be used, for example, As said nitrogen-containing monomer, 2-dimethylaminoethyl acrylate, acrylic acid 2- Diethylaminoethyl, 2-dimethylaminoethyl methacrylate, 2-diethylaminoethyl methacrylate, vinylpyridine, N-vinylcarbazole, vinylimidazole, and the like can be used.

  On the other hand, in the case of using a positively chargeable toner, fine particles having negative chargeability are used as the reverse polarity particles. For example, in addition to inorganic fine particles such as silica and titanium oxide, fluorine resin, polyolefin resin, silicone resin, polyester resin Fine particles composed of thermoplastic resins such as thermoplastic resins or thermosetting resins can be used, and a negative charge control agent that imparts negative chargeability to the resin can be contained, or fluorine-containing acrylic monomers and fluorine-containing methacrylates can be used. You may make it comprise the copolymer of a system monomer. Here, as said negative charge control agent, a salicylic acid type, a naphthol type chromium complex, an aluminum complex, an iron complex, a zinc complex etc. can be used, for example.

  In order to control the chargeability and hydrophobicity of the reverse polarity particles, the surface of the inorganic fine particles may be surface-treated with a silane coupling agent, a titanium coupling agent, silicone oil, etc. When imparting positive chargeability, surface treatment with an amino group-containing coupling agent is preferred, and when imparting negative chargeability, surface treatment with a fluorine group-containing coupling agent is preferred.

  The number average particle diameter of the reverse polarity particles is preferably 100 to 1000 nm. It is used by adding 0.1 to 10 parts by mass with respect to 100 parts by mass of toner.

  The carrier is not particularly limited, and a commonly used carrier can be used, and a binder type carrier, a coat type carrier, and the like can be used. Although it is not limited to this as a carrier particle size, 15-100 micrometers is preferable.

  The binder type carrier is obtained by dispersing magnetic fine particles in a binder resin, and positive or negative chargeable fine particles can be fixed to the carrier surface or a surface coating layer can be provided. Charging characteristics such as polarity of the binder type carrier can be controlled by the material of the binder resin, the chargeable fine particles, and the type of the surface coating layer.

  Examples of the binder resin used for the binder-type carrier include thermoplastic resins such as vinyl resins, polyester resins, nylon resins, polyolefin resins, and the like typified by polystyrene resins, and curable resins such as phenol resins. .

  Magnetic fine particles of the binder type carrier include spinel ferrite such as magnetite and gamma iron oxide, and magnets such as spinel ferrite and barium ferrite containing one or more metals other than iron (Mn, Ni, Mg, Cu, etc.). Plumbite type ferrite, iron or alloy particles having an oxide layer on the surface can be used. The shape may be granular, spherical, or needle-shaped. In particular, when high magnetization is required, it is preferable to use iron-based ferromagnetic fine particles. In consideration of chemical stability, it is preferable to use ferromagnetic fine particles of magnetoplumbite type ferrite such as spinel ferrite and barium ferrite containing magnetite and gamma iron oxide. A magnetic resin carrier having a desired magnetization can be obtained by appropriately selecting the type and content of the ferromagnetic fine particles. The magnetic fine particles are suitably added in an amount of 50 to 90% by mass in the magnetic resin carrier.

  Silicone resin, acrylic resin, epoxy resin, fluorine resin, etc. are used as the surface coating material of the binder type carrier, and these resins are coated on the surface and cured to form a coating layer, thereby providing a charge imparting ability. Can be improved.

  For example, the charging fine particles or the conductive fine particles can be fixed to the surface of the binder type carrier by, for example, mixing the magnetic resin carrier and the fine particles uniformly and adhering the fine particles to the surface of the magnetic resin carrier. By applying a strong impact force and fixing the fine particles so as to be driven into the magnetic resin carrier. In this case, the fine particles are not completely embedded in the magnetic resin carrier, but are fixed so that a part thereof protrudes from the surface of the magnetic resin carrier. As the chargeable fine particles, organic or inorganic insulating materials are used. Specifically, organic insulating fine particles such as polystyrene, styrene copolymers, acrylic resins, various acrylic copolymers, nylon, polyethylene, polypropylene, fluororesin, and cross-linked products thereof may be used as the organic type. Regarding the charge level and polarity, a desired level of charge and polarity can be obtained by a material, a polymerization catalyst, a surface treatment or the like. Further, as the inorganic type, negatively charged inorganic fine particles such as silica and titanium dioxide, and positively charged inorganic fine particles such as strontium titanate and alumina are used.

  On the other hand, a coated carrier is a carrier in which a carrier core particle made of a magnetic material is coated with a resin, and in a coated carrier, similarly to a binder-type carrier, positive or negatively chargeable fine particles are fixed to the carrier surface. it can. Charging characteristics such as polarity of the coat type carrier can be controlled by the type of the surface coating layer and the chargeable fine particles, and the same material as the binder type carrier can be used. In particular, the coating resin can be the same resin as the binder resin of the binder type carrier.

  The mixing ratio of the toner and the carrier may be adjusted so as to obtain a desired toner charge amount. The toner ratio is 3 to 50% by mass, preferably 6 to 30% by mass with respect to the total amount of the toner and the carrier. ing.

  In the developing device 2a shown in FIG. 1, the developer tank 24 is formed by a casing 19, and accommodates mixing stirring members 17 and 18 for circulating the developer while mixing and stirring. An ATDC (Automatic Toner Density Control) sensor 20 for detecting the toner concentration is preferably disposed at a position of the casing 19 facing the mixing and agitating member 18.

  The developing device 2 a has a toner replenishment unit 21 for replenishing toner in the developer tank 24 for the amount of toner consumed in the development region 6. In the toner supply unit 21, supply toner sent from a hopper (not shown) that stores supply toner is supplied into the developer tank 24.

  The developing device 2 a has a developer carrier 11 that faces the image carrier 1. The developer carrying member 11 includes a magnet roller 13 that is fixedly arranged and a rotatable sleeve roller 12 that includes the magnet roller 13. A developing bias for developing an electrostatic latent image is applied by a power source 51. The The magnet roller 13 has five magnetic poles N1, S1, N2, N3, and S2 along the rotation direction B of the sleeve roller 12. Of these magnetic poles, the main magnetic pole N1 is arranged at the position of the developing area 6 facing the image carrier 1, and the developer taking-in pole N3 is arranged in the vicinity of the developer taking-in area 7. Further, the same-polarity portions N <b> 2 and N <b> 3 that generate a repulsive magnetic field for peeling off the developer on the sleeve roller 27 are disposed at positions facing the inside of the developer tank 24.

  The developing device 2 a is disposed in the vicinity of the developer carrier 11, a partition member 14 that partitions the developer carrier 11 and a space on the developer supply side to which the developer is supplied, and the partition member 14. And an opening / closing member 15 that controls the amount of developer supplied to the developer carrier 11 by opening and closing the developer supply path to the developer carrier 11 from the space partitioned by.

  The partition member 14 and the opening / closing member 15 can intermittently change the communication state between the space portion stirred by the mixing stirring member 17 of the developer tank 24 and the developer carrier 11 side. By opening / closing the opening / closing member 15, the amount of developer supplied to the developer carrier 11 from the space stirred by the mixing stirring member 17 in the developer intake region 7 is controlled. In this way, by supplying the amount of developer necessary for the development region 6 to the surface of the developer carrier 11 by opening and closing the opening and closing member 15, the head height is conventionally regulated on the developer carrier and necessary. A regulating member for forming the developer layer thickness is not necessary. Therefore, the high stress on the developer that has conventionally occurred in the restricting portion is eliminated, and toner deterioration and carrier deterioration can be reduced.

  In this embodiment, in order to peel off the developer on the sleeve roller 12 on the upstream side in the developer transport direction from the partition member 14, a repulsive magnetic field is formed by the homopolar magnetic poles N 2 and N 3, and the development used in the development region 6. The developer is returned to the stirring region of the developer tank 24 (the space portion stirred by the stirring members 17 and 18). Instead of using such a homopolar magnetic pole, a scraping member such as a scraper may be provided so that the developer on the developer carrier 11 is peeled off and returned to the developer tank 24.

  The operation of the developing device 2a shown in FIG. 1 will be described in detail. The developer 23 in the developer tank 24 is mixed and stirred by the rotation of the mixing and stirring members 17 and 18, and is frictionally charged and simultaneously circulated and conveyed in the developer tank 24. The developer 23 that has been frictionally charged in the developer tank 24 is controlled to move toward the developer carrier 11 by the partition member 14 and the opening / closing member 15 provided in the developer intake region 7. When the opening / closing member 15 is open, a communication state between the stirring region of the developer tank 24 and the developer carrier 11 is ensured, and the stirring region in the developer tank 24 is generated by the magnetic attraction force of the developer intake pole N3. The developer is supplied to the sleeve roller 12 on the surface of the developer carrier 11. When the opening / closing member 15 is closed, the agitation region of the developer tank 24 and the developer carrier 11 are separated from each other in the developer intake region 7, and supply of the developer to the developer carrier 11 is blocked. It is done. When the open / close state of the open / close member 15 changes, the developer is intermittently supplied, and the developer amount necessary for the developer carrier 11 to develop the electrostatic latent image on the image carrier 1 is the developer carrier. It is supplied to the body 11. The developer supplied intermittently is held on the surface side of the sleeve roller 12 by the magnetic force of the magnet roller 13 inside the developer carrier 11 and rotates together with the sleeve roller 12 so as to face the image carrier 1. It is conveyed to area 6. In the process of transporting the developer, the developer supplied intermittently by receiving the history of developer rising by the magnetic pole S2 provided on the magnet roller 13 is homogenized on the developing sleeve. In the development region 6, developer spikes are formed by the magnetic force of the main magnetic pole N 1 of the magnet roller 13, and an electric field formed by the development bias applied to the developer carrier 11 and the latent image potential on the image carrier 1. Due to the force applied to the toner, the toner in the developer is supplied to the image carrier 1 and the electrostatic latent image is developed into a toner image. The development method may be a reversal development method or a regular development method. The developer that has consumed toner in the developing region 6 is conveyed to the developer separating region 8 as the sleeve roller 12 rotates while being held on the surface of the sleeve roller 12 by the magnetic force of the magnet roller 13, The developer is peeled off from the developer carrier 11 by the repulsive magnetic fields of the same pole portions N2 and N3 and collected into the stirring region of the developer tank 24. Here, since the space between the stirring area of the developer tank 24 and the developer carrier 11 is partitioned by the partition member 14 and the opening / closing member 15, the developer peeled off in the developer peeling area is surely developed. The collected developer is recovered to the stirring region of the tank 24, and the used developer that has developed the electrostatic latent image is removed from the surface of the developer carrier 11. When a toner supply control unit (not shown) provided in the toner supply unit 21 detects from the output value of the ATDC sensor 20 that the toner concentration in the developer 23 has become equal to or lower than the minimum toner concentration for ensuring image density, Replenished toner 22 stored in the hopper by a toner replenishing means (not shown) is supplied into the developer tank 24 via the toner replenishing portion 21.

  Here, the operation of the opening / closing member 15 will be described with reference to FIG. 2, the opening / closing member 15 has a so-called valve configuration in which one end is fixed to the casing 19 and the other end is a free end, and the free end can swing around the fixed end. Further, in FIG. 2, an opening / closing control member 16 having a polygonal cross section (hexagonal in the figure) is provided in contact with the opening / closing member 15.

  When the opening / closing control member 16 rotates, the opening / closing member 15 is pressed at the polygonal apex. In other words, the opening / closing member can be changed from the state of FIG. 2A to the state of FIG. 2B by the rotation of the opening / closing control member 16. Here, the partition member 14 provided between the developer carrier 11 and the stirring region of the developer tank 24 is provided so as to contact the opening / closing member 15 in the state of FIG.

  In the state of FIG. 2A, the developer carrier 11 and the stirring area of the stirring tank 24 are separated from each other with the apex of the polygon of the opening / closing control member 16 pushing the opening / closing member 15, and the developer supply is performed. Blocked.

  On the other hand, in the state of FIG. 2B, the polygonal linear portion of the opening / closing control member 16 is in contact with the opening / closing member 15, and the opening / closing member 15 moves in a direction to tilt toward the developer carrier 11. Therefore, a state in which the developer carrier 11 and the stirring region of the stirring tank 24 communicate with each other is formed, and the developer in the stirring region of the developer tank 24 is loaded with the developer by the magnetic force of the developer intake pole N3 of the magnet roller 13. It is sucked into the body 11.

  In this way, the closed state in FIG. 2A and the open state in FIG. 2B are alternately changed by the rotation of the opening / closing control member 16, and intermittently from the stirring region of the developer tank 24 to the developer carrier 11. Developer supply can be performed.

  The opening area and the opening time of the opening / closing member 15 may be set as appropriate so that the developer carrier 11 carries a developer amount necessary for development. Since the developer supply to the developer carrier 11 is intermittently performed, the developer on the developer carrier 11 immediately after the supply may be uneven. However, the developer is accompanied by the rotation of the sleeve roller 12. In the process of being conveyed, the effect of leveling by the spikes at the conveying pole S2 is obtained. Further, the conveyance unevenness can be suppressed by shortening the opening / closing cycle of the opening / closing member 15.

  Further, in FIG. 2, the opening / closing control member 16 is configured to be closed when the apex of the polygonal cross section of the opening / closing control member 16 comes into contact with the opening / closing member 15. It is also possible to change the ratio between the closed state and the open state (for example, by arranging as shown in FIG. 2C and FIG. 2D), the vertex of the cross-sectional polygon of the opening / closing control member 16 is changed to the opening / closing member 15. The opening / closing member 15 is bent when it comes into contact).

  The opening / closing member 15 is not particularly limited, and metal, resin, rubber, or the like can be used as long as it has elasticity and functions as a leaf spring.

  In FIG. 2, a member having a polygonal cross section is used as the opening / closing control member 16. However, the member is not limited to this, and for example, a member having a cross sectional shape composed of an arc and a straight line as shown in FIG. Is possible. In this configuration, when the arc of the opening / closing control member 16 comes into contact with the opening / closing member, the closed state (FIG. 3A), and when the side (straight line portion) comes into contact, the open state (FIG. 3B) is obtained. . Further, the opening / closing control member 16 is not limited to a rotating body, and any member may be used as long as the opening / closing member 15 can be controlled to be closed.

  Further, the opening / closing member 15 is not limited to the valve, and may be a shutter member 26 that switches the opening / closing state by parallel movement as shown in FIG. 4, for example. In this configuration, the shutter member 26 is in the closed state in the state of FIG. 4A, and the shutter member 26 is in the open state in the state of FIG. 4B in which the shutter member 26 is translated to the stirring region side of the developer tank 24. Further, it may be a rotating body as shown in FIG. The state of FIG. 5A shows a closed state in which the vertex of the rotating body 27 having a polygonal cross section is in contact with the partition member 14, and FIG. An open state is shown with an opening formed between the member 14 and the member 14.

  In the present invention, since the developer supply to the developer carrier 11 is intermittently performed, the developer layer may be uneven depending on conditions. In such a case, a leveling member 28 may be provided between the developer taking-in area 7 and the developing area 6 as shown in FIG. The leveling member 28 is not intended to block and regulate the developer, but to average the developer supplied intermittently, and does not give excessive stress to the developer. The leveling member 26 may be a fixed member or a rotating member.

  FIG. 7 shows another embodiment according to the present invention. In FIG. 7, the developing device 2 b includes a toner carrier 30 that is disposed to face the developer carrier 11, separates the toner from the developer on the developer carrier 11, and carries the toner on the surface. A power source 52 for applying a developing bias for developing the electrostatic latent image on the image carrier 1 is connected to the toner carrier 30, and toner is applied to the toner carrier 30 to the developer carrier 11. A power supply 53 is connected so as to apply a toner supply bias for supply.

  With such a configuration, the developer leveling effect by the magnetic pole N1 can be obtained in the toner supply region 9, and the electrostatic latent image is developed once the toner layer is formed. The effect which further reduces is acquired.

  The toner carrier 30 may be made of any material as long as the voltage can be applied. For example, an aluminum roller subjected to a surface treatment may be used. In addition, on a conductive substrate such as aluminum, for example, polyester resin, polycarbonate resin, acrylic resin, polyethylene resin, polypropylene resin, urethane resin, polyamide resin, polyimide resin, porsulfone resin, polyether ketone resin, vinyl chloride resin, vinyl acetate You may use what gave resin coatings, such as resin, a silicone resin, a fluororesin, and rubber coatings, such as silicone rubber, urethane rubber, nitrile rubber, natural rubber, and isoprene rubber. The coating material is not limited to this. Further, a conductive agent may be added to the bulk or surface of the coating. Examples of the conductive agent include an electronic conductive agent or an ionic conductive agent. Examples of the electronic conductive agent include carbon black such as kettin black, acetylene black, and furnace black, metal powder, and metal oxide fine particles, but are not limited thereto. Examples of the ionic conductive agent include cationic compounds such as quaternary ammonium salts, amphoteric compounds, and other ionic polymer materials. Furthermore, a conductive roller made of a metal material such as aluminum may be used.

  As described above, according to the configuration of the present invention, the developer necessary for the developer carrying member can be supplied with low stress, and the development that has been the main cause of developer deterioration in the conventional two-component development method. Restriction of head height on the agent carrier is not required. Therefore, it is possible to provide a developing device and an image forming apparatus that can obtain a high-quality image over a long period of time without applying high stress to the developer.

1 is a schematic configuration diagram illustrating a main part of an image forming apparatus and a developing device according to an embodiment of the present invention. FIG. 3 is a schematic configuration diagram in which a developer taking-in area for supplying a developer to a developer carrying member is enlarged. FIG. 3 is a schematic configuration diagram in which a developer taking-in region for supplying a developer to a current developer carrying member is enlarged. FIG. 3 is a schematic configuration diagram in which a developer taking-in area for supplying a developer to a developer carrying member is enlarged. FIG. 3 is a schematic configuration diagram in which a developer taking-in area for supplying a developer to a developer carrying member is enlarged. FIG. 3 is a schematic configuration diagram showing that a leveling member is provided between a developer intake area and a development area. It is a schematic block diagram which shows the principal part of the image forming apparatus by another embodiment which concerns on this invention, and a developing device.

Explanation of symbols

1 Image carrier (photoreceptor)
2a, 2b Developing device 3 Charging member 4 Transfer roller 5 Cleaner 6 Development area 7 Developer intake area 8 Developer separation area 9 Toner supply area 11 Developer carrier 12 Sleeve roller 13 Magnet roller 14 Partition member 15 Open / close member 16 Open / close control Member 17 Mixing and stirring member 18 Mixing and stirring member 19 Casing 20 ATDC sensor 21 Toner supply part 22 Supply toner 23 Developer 24 Developer tank 26 Shutter member 27 Rotating body 28 Leveling member 30 Toner carrier 51, 52, 53 Power source A image Carrier rotation direction B Sleeve roller rotation direction C Paper feeding direction D Toner carrier rotation direction E Exposure position P Transfer medium

Claims (10)

In a developing device including a developer carrying member that carries and conveys a developer containing toner and a carrier on the surface by magnetic force,
A partition member disposed in the vicinity of the developer carrier, and partitioning the developer carrier and a space on the side where the developer is supplied to the developer carrier;
An opening / closing member that controls the amount of developer supplied to the developer carrier by opening and closing a developer supply path from the space partitioned by the partition member to the developer carrier. Developing device. The developing device according to claim 1, wherein the developer carrying member is a magnet roller having a magnetic pole therein. 3. The magnetic magnet according to claim 2, wherein the magnet roller has a homopolar magnetized portion so that the developer conveyed by the magnet roller is separated from the partition member on the upstream side in the developer conveying direction. Development device. The opening / closing member is a valve having one end fixed and a free end that can be swung at the other end, and swings the valve to control the supply of the developer from the developer tank to the developer carrier. The developing device according to claim 1, further comprising an opening / closing control member. The developing device according to claim 4, wherein the opening / closing control member is a rotating body having a polygonal cross section. The developing device according to claim 4, wherein the opening / closing control member is a rotating body having a cross section of an arc and a straight line. 4. The development according to claim 1, wherein the opening / closing member is a shutter member that controls a communication state between the developer carrying member and the developer tank by moving in parallel. 5. apparatus. The developing device according to claim 1, wherein the opening / closing member is a rotating body having a polygonal cross section for switching a communication state by rotation. 9. The toner carrier according to claim 1, further comprising a toner carrier that is disposed to face the developer carrier, separates the toner from the developer on the developer carrier, and carries the toner on the surface. 2. The developing device according to item 1. The development according to any one of claims 1 to 9, wherein the image carrier, means for forming an electrostatic latent image on the image carrier, and the electrostatic latent image on the image carrier are developed. And an image forming apparatus.

Images