JP2007322721A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of improving electrostatic charging property of a developer by carrying a developer for replenishment and an existent developer while mixing and agitating them, and a process cartridge and an image forming apparatus including the developing device. <P>SOLUTION: The developing device 1 having a screw member which is provided in a development container 2 and has a spiral rotating blade 15b formed on a rotating shaft 15a driven to rotate and carries the developer toward a developer carrier 3 is characterized in that the rotating blade 15b of the screw member has a magnetic field producing member 11 on a spiral surface on a downstream side in the developer carrying direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention generally relates to a developing device that develops an electrostatic image formed on an image carrier by an electrophotographic system, an electrostatic recording system, or the like to form a visible image. Further, the present invention relates to a process cartridge in which such a developing device is integrated into a cartridge with an image carrier, and an image forming apparatus such as a copying machine, a printer, and a facsimile provided with such a developing device.

  Two-component development method that uses non-magnetic toner and magnetic carrier as a developer is widely used in conventional electrophotographic image forming devices, especially color image forming devices that form chromatic images. Has been. The two-component development system has advantages such as image quality stability and apparatus durability compared to other currently proposed development systems.

  In a developing device using a two-component developing system, when toner is supplied to an image carrier and development is performed, the toner concentration in the developer gradually decreases. In order to prevent this decrease in toner density, it is necessary to replenish new toner.

  11 and 12 show a schematic configuration of a conventional general two-component developing apparatus 1A.

  The developing device 1 </ b> A includes a developing container 2 including a developing sleeve 3 that supplies a developer to the image carrier 28. The developing container 2 is disposed along the axial direction of the developing sleeve 3, and develops the developer while mixing and stirring the developer supply unit 12 that supplies the developer to the developing sleeve 3 and the replenishment toner and the developer. The developer supply unit 12 includes a developer stirring unit 13 that conveys in the opposite direction. The developer supply unit 12 and the developer stirring unit 13 are communicated with each other through the first and second communication openings 16 and 17.

  The developer supply unit 12 and the developer agitation unit 13 are provided with developer agitation and conveyance members 14 and 15 for conveying and agitating the developer, respectively. 12 and the developer stirring unit 13.

  The developer agitating and conveying members 14 and 15 are generally provided with spiral agitating members 14b and 15b on the circumferential surfaces of the cylindrical shafts 14a and 15a.

  The amount of toner consumed by image formation passes through the supply port 6 from the toner cartridge 5 and is conveyed to the supply screw 8 provided in the developing container 2. Next, as the supply screw 8 rotates, the developer container 2 is supplied through the toner supply opening 9.

  The replenished toner comes into contact with the magnetic carrier and is triboelectrically charged when mixed and stirred with the two-component developer in the developer stirring unit 13.

  However, if the stirring in the developer stirring unit 13 is insufficient, the replenished toner is conveyed to the developer supply unit 12 from the first communication opening 16 without being sufficiently charged. As a result, since toner that is not sufficiently charged is used for the developing operation, fogging due to the developer, that is, toner fogging, occurs on the white background portion of the image, resulting in deterioration of image quality.

  Such toner fog is more likely to occur as the developer surface height (h) of the developer agitating unit 13 increases. This is because when the developer surface height (h) is higher than that of the agitating / conveying member 15, the replenished toner becomes difficult to be taken into the developer, so that the developer cannot be brought into contact with the magnetic carrier and a sufficient charge amount is obtained. This is because the toner is conveyed to the developer supply unit 12 without being obtained.

Patent Document 1 describes a technique for improving the charging property of toner. According to the developing device of Patent Document 1,
(1) A configuration in which the thickness (F) of the root of the spiral blade portion of the stirring screw and the pitch (p) of the stirring screw are 0.6 ≦ F / p ≦ 1,
(2) A configuration in which the thickness (F) of the root of the spiral blade portion of the stirring screw and the pitch (p) of the stirring screw are 0.4 ≦ F / p ≦ 1, 6 mm ≦ p, and
(3) A configuration in which the spiral angle θ in the axial direction of the blade portion is 30 to 75 degrees,
Has been proposed.
JP-A-10-171251

  However, in the developing device described in Patent Document 1 as well, if the developer height is higher than that of the stirring screw, the toner fog is generated.

  Further, the phenomenon that the developer surface height is increased in the developer agitation unit 13 as described above is caused by the development device, that is, the process so that the developer agitation unit 13 is vertically lower than the developer supply unit 12. This occurs remarkably when the cartridge or the image forming apparatus is used at an angle.

  Accordingly, a main object of the present invention is to provide a developing device capable of transporting a developer for replenishment and an existing developer while mixing and stirring, and to improve the chargeability of the developer, and such a developing device. A process cartridge and an image forming apparatus are provided.

The above object is achieved by a developing device, a process cartridge, and an image forming apparatus according to the present invention. In summary, according to the first aspect of the present invention, a developer container containing a magnetic developer;
A developer carrying member provided in the developing container, carrying and transporting the developer, and developing an electrostatic image formed on the image carrying member;
A screw member that is provided in the developer container and has a spiral rotary blade formed on a rotary shaft that is driven to rotate; and a screw member that conveys the developer toward the developer carrier;
Developer replenishing means for replenishing the developer container with replenishment developer;
In a developing device comprising:
A developing device is provided in which the rotating blade of the screw member has a magnetic field generating member on a spiral surface on the downstream side in the developer conveying direction.

  According to a second aspect of the present invention, there is provided a process cartridge in which at least the image carrier and the developing device are integrated, and the developing device is the developing device having the above-described configuration. Is done.

  According to a third aspect of the present invention, in the image forming apparatus in which the process cartridge is detachable from the main body of the image forming apparatus, the process cartridge is the process cartridge having the above-described configuration. Is provided.

  According to a fourth aspect of the present invention, an image carrier, a developing device that develops an electrostatic image on the image carrier using a developer to form a visible image, and a replenishment developer to the developing device. An image forming apparatus having a developer replenishing means for replenishing the image forming apparatus is provided, wherein the developing apparatus is a developing apparatus having the above-described configuration.

  According to the present invention, it is possible to improve the chargeability of the developer in the conveyance path in which the replenishment developer and the developer are conveyed while being mixed and stirred.

  Hereinafter, a developing device according to the present invention, and a process cartridge and an image forming apparatus including such a developing device will be described in more detail with reference to the drawings.

Example 1
FIG. 1 shows a schematic configuration of an image forming apparatus according to the present invention. In this embodiment, the image forming apparatus is an inline type color electrophotographic image forming apparatus, but the image forming apparatus of the present invention is not limited to this.

  First, a schematic configuration of the image forming apparatus of this embodiment will be described.

(Overall configuration and operation of image forming apparatus)
In FIG. 1, the image forming apparatus has four image forming stations P (Pa, Pb, Pc, Pd). In this embodiment, the four image forming stations P are a yellow image forming station Pa, a magenta image forming station Pb, a cyan image forming station Pc, and a black image forming station Pd.

  Each image forming station P includes a drum-shaped electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) 28 (28Y, 28M, 28C, 28K) as an image carrier. Around the photosensitive drum 28, a primary charger 21 (21Y, 21M, 21C, 21K) as primary charging means for forming an electrostatic image on the photosensitive drum 28, and a laser beam scanner device as exposure means. 22 (22Y, 22M, 22C, 22K) are arranged. Further, around the photosensitive drum 28, a developing device 1 (1Y, 1M, 1C, 1K) as a developing unit for developing the electrostatic image on the photosensitive drum 28 into a visible image (that is, a toner image). Is placed. Below each photosensitive drum 28, a transfer belt 24 as a transfer material carrier for carrying and transporting a transfer paper 27 as a recording material to each image forming station P is disposed. Further, primary transfer rollers 23 (23Y, 23M, 23C, 23K) as transfer means are arranged at positions facing the respective photosensitive drums 28. Further, in order to remove the transfer residual toner on the photosensitive drum 28, a cleaning device 26 (26Y, 26M, 26C, 26K) as a cleaning unit is provided to face the photosensitive drum 28.

  Next, an image forming operation in the image forming apparatus having the above configuration will be described.

  First, in the yellow image forming station Pa, the surface of the photosensitive drum 28Y charged by the primary charger 21Y is exposed by the laser beam scanner device 22Y, thereby forming an electrostatic image on the photosensitive drum 28Y. This latent image is developed by the developing device 1Y to form a toner image on the photosensitive drum 28Y.

  This toner image is transferred onto the transfer paper 27 on the transfer belt 24 by the transfer bias by the primary transfer roller 23Y.

  A similar image forming operation is performed at the magenta image forming station Pb, the cyan image forming station Pc, and the black image forming station Pd, and the toner images on the photosensitive drum 28 are sequentially transferred onto the transfer paper 27. As a result, a desired full-color image is formed on the transfer paper 27.

  The transfer paper 27 is peeled off from the transfer belt 24 and pressed / heated by the fixing device 25 to obtain a permanent image. Further, the residual toner remaining on the photosensitive drum 28 after the transfer is removed by the cleaning device 26 to prepare for the next image formation.

  Next, an example of a developing device used in the image forming apparatus will be described.

(Developer)
In the following description, the developing device 1 is a general term for the yellow developing device 1Y, the magenta developing device 1M, the cyan developing device 1C, and the black developing device 1K.

  With reference to FIGS. 2 and 3, the developing device according to the present embodiment will be described. FIG. 2 is a schematic sectional view of the developing device, and FIG. 3 is a top view of the developing device.

  The developing device 1 includes a developing container 2 in which a two-component developer T composed of a nonmagnetic toner and a magnetic carrier is accommodated. The toner concentration in the developer in the initial state is 7 wt%. This value should be appropriately adjusted depending on the charge amount of the toner, the carrier particle size, the configuration of the image forming apparatus, and the like, and does not necessarily have to follow this value.

  The developing container 2 of the developing device 1 includes an opening 2A that opens in a developing area A that faces a photosensitive drum 28 as an image carrier. A developing sleeve 3 as a developer carrying member is rotatably arranged so as to be partially exposed to the opening 2A. The developing sleeve 3 is made of a non-magnetic material, and includes a fixed magnet roll 4 serving as a magnetic field generating means.

  The developing container 2 is divided into two chambers, a developing chamber 12 as a developer supply unit nearer to the developing sleeve 3 and a stirring chamber 13 as a developer stirring unit farther from the developing sleeve 3 by the partition wall 2B. Yes. First and second openings 16 and 17 are formed at both ends of the partition wall 2B, that is, the front side and the back side in FIG. 12 and the stirring chamber 13 communicate with each other.

  Further, the developing chamber 12 and the stirring chamber 13 are respectively provided with a first conveying member 14 and a second conveying member 15, and the developer is mixed and circulated in the developing container 2 by these conveying members 14 and 15. Stir. In other words, in the present embodiment, the developing chamber 12 and the stirring chamber 14 form first and second transport paths that are developer transport paths by the first and second transport members 14 and 15, respectively.

  In the developing device 1 of this embodiment, the developer circulation direction is the direction from the back side to the near side in FIG. 2 in the developing chamber 12, and from the near side to the far side in FIG. It is the direction to go.

  The developing sleeve 3 rotates in the direction of the arrow in FIG. 2 during the developing operation, is regulated by the developer regulating member 18, holds the two-component developer in the developing container 2 in a layered manner, and faces the photosensitive drum 28. A two-component developer is supplied to A. As a result, the electrostatic image formed on the surface of the photosensitive drum 28 is developed into a visible image (that is, a toner image).

  The developer after developing the electrostatic image is conveyed according to the rotation of the developing sleeve 3 and collected in the developing chamber 12 in the developing container 2.

  As understood with reference to FIG. 4, the toner cartridge 5 as the developer replenishing means is substantially cylindrical in this embodiment, and can be easily detached from the image forming apparatus main body. The toner cartridge 5 can be inserted from the front side in FIG. 2 and attached to the image forming apparatus. The toner cartridge 5 is rotated by twisting the handle 5a on the front side to the right, and the supply port 6 is opened.

  When the toner cartridge 5 is detached from the image forming apparatus, the replenishing port 6 is closed by twisting the handle 5a to the left, and the contained powder (that is, replenishment developer) does not leak to the outside.

  Further, the toner cartridge 5 incorporates a conveying screw 7 for conveying a replenishing developer (hereinafter referred to as “replenishing toner”). FIG. 4 shows a part of the inside of the toner cartridge 5. As shown in FIG. 4, the conveying screw 7 is configured such that a resin film or the like spirally driven by a rigid shaft 7 a is rotated. Is done. With this configuration, by rotating the shaft 7a as appropriate, the toner in the toner cartridge 5 is conveyed and replenishment is assisted.

  The developer concentration in the developing device 1 is detected by the developer concentration detecting device 10, and the toner consumed by the image formation is supplied from the toner cartridge 5. The replenishment toner in the toner cartridge 5 is conveyed from the toner cartridge 5 through the replenishment port 6 to the replenishment screw 8 disposed in the developing container 2 by the rotational force and gravity of the conveyance screw 7. Next, as the supply screw 8 rotates, the developer container 2 is supplied through the toner supply opening 9.

  Next, the two-component developer T used in this embodiment will be described.

  The non-magnetic toner constituting the two-component developer T includes a binder resin, a colorant, and, if necessary, colored resin particles containing other additives and an external additive such as colloidal silica fine powder. A negatively chargeable polyester resin produced by a pulverization method. The volume average particle size is preferably 5 μm or more and 9 μm or less. In this example, it was 7.2 μm.

As the magnetic carrier, for example, surface oxidized or unoxidized iron, nickel, cobalt, manganese, chromium, rare earth and other metals and their alloys, or oxide ferrite can be preferably used. The method for producing these magnetic particles is not particularly limited. The carrier has a weight average particle diameter of 20 to 50 μm, preferably 30 to 40 μm, and a resistivity of 10 ⁷ Ωcm or more, preferably 10 ⁸ Ωcm or more. In this example, a 10 ⁸ Ωcm one was used.

  Incidentally, the volume average particle diameter of the toner used in this example was measured by the following apparatus and method.

  As a measuring device, a Coulter counter TA-II type (manufactured by Coulter), an interface for outputting number average distribution and volume average distribution (manufactured by Nikka), and a CX-I personal computer (manufactured by Canon) are used. A 1% NaCl aqueous solution prepared using primary sodium chloride was used as the electrolytic aqueous solution. The measuring method is as follows.

  That is, 0.1 ml of a surfactant, preferably alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the above electrolytic aqueous solution, and 0.5 to 50 mg of a measurement sample is added. The aqueous solution of the electric field in which the sample is suspended is dispersed for about 1 to 3 minutes with an ultrasonic disperser, and the particle size distribution of 2 to 40 μm particles is measured using the above Coulter Counter TA-II with a 100 μm aperture as the aperture. To obtain a volume average distribution. The volume average particle diameter is obtained from the volume average distribution thus obtained.

  The resistivity of the carrier used in this example was measured by the following method.

  That is, using a sandwich type cell having a measurement electrode area of 4 cm and an interelectrode spacing of 0.4 cm, an applied voltage E (V / cm) between both electrodes is applied to one electrode under a pressure of 1 kg. Measured by a method of obtaining the carrier resistivity from the current flowing in the circuit.

(Conveying member of stirring chamber)
Next, the conveyance member of the stirring chamber 13 as the second conveyance path, that is, the second conveyance member 15, which is a characteristic part of the present embodiment, will be described.

  Referring to FIG. 3, the first transport member 14 and the second transport member 15 both have shafts 14 a and 15 a having a shaft diameter (d) of 6 mm and a spiral shape (that is, a spiral) having a diameter (D) of 16 mm. ) Rotating blades 14b and 15b. In addition, the rotary blades 14b and 15b are arranged on the shaft circumferential surface at a pitch interval (P) of 15 mm in this embodiment.

  The first conveying member (hereinafter referred to as “first screw”) 14 and the second conveying member (hereinafter referred to as “second screw”) 15 are spirally formed at the downstream ends of the respective developer conveying directions. It has return rotary blades 14c and 15c. The return rotary blades 14c and 15c are twisted in the direction opposite to the twist direction of the corresponding first screw 14 and second screw 15, and push back the developer in the direction opposite to the developer transport direction. This facilitates the delivery of the developer at the first and second communication openings 16 and 17.

  According to the present embodiment, the magnetic field generating member 11 that is a magnet is provided on the downstream side surface of the rotary blade 15 b of the second screw 15.

  FIG. 5A is a schematic configuration perspective view illustrating the second screw 15.

  In the second screw 15, the magnet 11 is provided in a spiral shape along the outer peripheral end of the downstream surface of the spiral rotating blade 15 b in the developer conveying direction.

  That is, in this embodiment, the magnet 11 is an elongated thin plate-like magnet, and is arranged in a spiral shape near the outside in the radial direction on the downstream spiral surface of the rotating blade 15b of the second screw 15 in the developer conveying direction. In the present embodiment, as shown in FIG. 5B, the magnet 11 has a width (w) of 2 mm and a thickness (t) of 1 mm, and an adhesive or welding is provided on the spiral surface of the rotary blade 15b. Fixed integrally.

  For the developer circulation performance, the magnet 11 is not provided on the return rotary blade 15c that transports the developer in the direction opposite to the developer transport direction.

  The magnet 11 only needs to have a magnetic flux density of 100 mT or more, such as an Sm—Co magnet, an Nd—Fe—B magnet, or a ferrite magnet. In this example, a ferrite magnet was used. The magnetic flux density of the magnet 11 was 200 mT.

  As shown in FIG. 5C, the magnet 11 can form different magnetic poles on both side surfaces in the thickness (t) direction. That is, a large number of same poles (for example, S poles) can be formed on the first surface of the spiral surface, and a large number of poles (for example, N poles) different from the first surface can be formed on the second surface on the opposite side. Further, as shown in FIG. 5D, different magnetic poles (S pole and N pole) may be arranged alternately along the spiral surface.

  Further, in the developing device 1 of this embodiment, as shown in FIG. 3, the substantially central position of the toner supply opening 9, that is, the toner supply position from the toner cartridge 5 to the second screw 15 is the second opening 17. Therefore, it is set to the downstream side in the developer conveyance direction. In the present embodiment, the toner replenishment position Tp, that is, the distance (Lt) in the downstream direction from the end 2Ba of the partition wall 2B that forms the second communication opening 17 on the upstream side in the developer conveyance direction of the stirring chamber 13 is 10 mm. It is said.

(Chargeability)
Hereinafter, experimental results on the charge imparting property to the replenishment toner in the developing device 1 of the present embodiment will be described.

[Experiment]
In this experiment, 1 g of toner was replenished at the toner replenishment opening 9, and the charge amount of the replenished toner at the first communication opening 16 was measured.

  6 and 7 show the results of toner chargeability in this experiment. The toner chargeability is determined by changing the charge amount of 3000 toners to HOSOKAWA MICRON Corp. It measured by E-Spart Analyzer made from a company.

  As is well known, the toner fogged on the white background of the image is a toner having a polarity opposite to the normal polarity (positive polarity in the case of the toner of the present embodiment) or a charge amount of 0.

  Therefore, if all of the toner replenished upstream of the second screw 15 in the developer conveyance direction is negative in the first communication opening 16 downstream of the second screw 15 in the developer conveyance direction, the toner fogs. There is no.

  Further, the angle θ shown in FIGS. 6 and 7 is inclined from the position of the developing device 1 shown in FIG. 2 to the developing chamber 12 vertically upward and the stirring chamber 13 vertically downward as shown in FIG. Angle (hereinafter referred to as “inclination angle θ”).

  FIG. 6 shows the toner chargeability when no magnet is attached to the second screw 15. In this case, when the inclination angle is larger than 5 °, toner having a positive polarity or a charge amount of 0 exists in the first communication opening 16. The reason for this will be described below.

  As shown in FIG. 9A, as the inclination angle θ increases, the relationship between the gravity direction of the developer T and the developer transport direction changes, and the developer T becomes difficult to be transported to the developing chamber 12. As a result, the amount of developer stored in the stirring chamber 13 increases, and when the inclination angle becomes 5 ° or more, the rotary blade 15b of the second screw 15 is covered with the developer (see FIG. 8). It becomes impossible to take the toner Ts into the existing developer T. Therefore, the replenishment toner Ts is conveyed to the first communication opening 16 without being sufficiently charged with the carrier by friction.

  Next, FIG. 7 shows toner chargeability when the magnet 11 is attached to the downstream surface side of the second screw 15.

  In the case of the developing device 1 of the present embodiment, when the inclination angle is 10 ° or less, there is no toner having positive polarity or no charge amount in the first opening portion 16. The reason for this will be described below.

  As described above, the developer amount accommodated in the stirring chamber 13 increases as the inclination angle θ increases, but the magnetic force and rotation of the magnet 11 attached to the second screw 15 as shown in FIG. By operation, the replenishment toner Ts floating on the developer T is taken into the developer T together with the developer around the magnet. Therefore, the replenishment toner Ts can be sufficiently charged by friction with the carrier.

  As described above, by adopting the configuration of the developing device 1 of the present embodiment, the replenishment toner Ts and the existing developer T are mixed and agitated, and the developer is conveyed to the developer in the agitating chamber. Chargeability can be improved. For this reason, even when the developing device, that is, the image forming apparatus is used at an angle, it is possible to prevent toner fogging on the white background portion of the image.

  Further, the function and effect of the developing device of the present embodiment having the above configuration will be described in more detail.

In general, in order to sufficiently frictionally charge the replenished toner with the carrier, the following three performances are required for the developer agitation unit.
(1) Capability to take in the replenishment toner into the developer (2) Dispersibility to release the replenishment toner (3) Mixability to mix the replenishment toner with the carrier in the developer. The above items will be described below.

  In general, toner replenishment to the developing device is often a system in which the toner is freely dropped onto the developer circulating in the developer circulation path. In this system, the replenishment toner tends to float on the developer.

  In order to mix the replenishment toner with the carrier in the developer, it is necessary to first take in the replenishment toner floating on the developer into the developer. Therefore, in a general developing device, the replenishing toner is taken into the developer by a so-called screw having a spiral-shaped member provided on the circumferential surface of the cylindrical shaft. In order to further improve the uptake performance, a quadrangular or trapezoidal member may be additionally provided on the circumferential surface of the cylindrical shaft.

  In general, in order to stabilize the toner replenishment accuracy, a certain amount of pressure is applied to the toner immediately before being replenished to the developing device, and the toner is replenished in a certain degree of aggregation. Therefore, in order to uniformly mix the replenishment toner with the carrier in the developer, it is necessary to release and disperse the toner in a certain degree of aggregation. For this reason, in a general developing device, the toner replenished by the above-described screw is released and dispersed.

  In order to sufficiently charge the toner, it is necessary to actively perform a mixing operation in which the toner and the carrier are brought into contact with each other. For this reason, in a general developing device, the toner replenished by the screw and the carrier are mixed.

  In order to sufficiently charge the replenished toner, it is necessary to satisfy these three performances with a screw. However, in the conventional developing device configuration, since the replenishment toner intake performance is low, toner fog occurs. It was.

  It is the stirring member that substantially transports and stirs the two-component developer. For this reason, in the developer stirring section, the height of the developer surface in the vicinity of the upper surface on the downstream side of the developer conveying direction of the stirring member (hereinafter referred to as the “downstream side surface”) is the highest, so that the replenishment toner intake performance is reduced. It occurred.

  Therefore, the developing device of the present embodiment is provided with a magnetic field generating member on the downstream side surface of the spiral stirring member of the developer stirring / conveying member in the developer stirring chamber. As a result, a magnetic spike is formed by the two-component developer on the downstream side surface of the spiral stirring member, and the replenishment toner uptake performance is improved by the magnetic spike.

  Therefore, compared with the conventional developing device, the developing device according to the present embodiment has remarkably high replenishment toner capturing performance. That is, the chargeability of the toner in the developer stirring chamber is extremely high. For this reason, even when the image forming apparatus, that is, the developing device is used at an angle, the replenishment toner can be sufficiently charged, thereby preventing the toner fog on the white background portion of the image.

  Furthermore, the magnetic field generating member need not be provided on the entire downstream side surface of the stirring member, and may be provided in the vicinity of the radial end of the stirring member. In other words, it is only necessary to prevent a decrease in uptake property when the developer surface height is substantially the same as the conveying member or higher than the stirring member.

  As can be understood from the description of the above embodiments, the chargeability of the toner in the stirring chamber for conveying the developer to the developing chamber can be improved while mixing and stirring the replenishment developer and the developer. As a result, even when the image forming apparatus is used at an angle, it is possible to prevent the toner fog on the white background portion of the image.

(Process cartridge)
In the image forming apparatus of the present embodiment, the developing device 1 can be a process cartridge 30 formed into a cartridge together with the photosensitive drum 28, the primary charger 21, and the cleaning device 26, as shown in FIG. In this case, it is needless to say that the same effect as that of the present embodiment is obtained.

  In FIG. 10, the toner cartridge 5 is not shown. The process cartridge 30 is operatively connected to the toner cartridge 5 mounted on the apparatus main body in a state where the process cartridge 30 is mounted on the image forming apparatus main body, and can receive replenishment toner from the toner cartridge 5. It is configured.

  In general, when the photosensitive drum reaches the end of its life or the developer in the developing device is significantly deteriorated, the entire process cartridge can be taken out from the main body of the image forming apparatus and a new process cartridge can be mounted. As a result, the image forming apparatus can be restored, so that it is possible to improve the maintainability.

  In addition, because of this high maintainability, the user can do it without relying on a service person who has expertise in equipment replacement, so that the running cost of the image forming apparatus can be reduced by reducing the labor cost. .

  Also in the case of a process cartridge, since the developing device 1 is used, the movement of the developer in the stirring chamber 13 is the same as the developing device described with reference to FIGS. Further, the charge imparting property of the replenishment toner in the stirring chamber 13 has the same characteristics as the developing device shown in FIGS.

  That is, even when the inclination angle θ of the process cartridge 30, that is, the developing device 1 is increased and the amount of developer stored in the stirring chamber 13 is increased, the following effects can be obtained. That is, due to the magnetic force and rotation of the magnet 11 attached to the second screw 15, the replenishment toner floating on the developer is taken into the developer together with the developer around the magnet, and the replenishment toner is sufficiently charged by friction with the carrier. can do.

  In this embodiment, the process cartridge 30 is a unit in which the photosensitive drum 28, the primary charger 21, the cleaning device 26, and the developing device 1 are integrated. However, the process cartridge 30 is not particularly limited to this configuration. That is, the configuration of the process cartridge may be determined as appropriate in consideration of the user's maintainability, the lifetime of each element, and the like. For example, at least the photosensitive drum 28 and the developing device 1 may be integrated. Furthermore, it is also possible to make only the developing device into a cartridge and make it detachable from the image forming apparatus main body.

  In this embodiment, the image forming apparatus is described as an inline type color image forming apparatus. However, the present invention is not limited to this, and the inline type color image forming apparatus is an image forming apparatus according to the present invention. This is just an example. It goes without saying that the developing device having the characteristics of this embodiment has the same effects as those of this embodiment in any configuration of the image forming apparatus.

  For example, the image forming apparatus of the above embodiment is a direct transfer type color image forming apparatus that directly transfers an image of each image forming station to a recording material, but is not limited thereto. For example, an intermediate transfer type color image forming apparatus in which an image of each image forming station is once transferred to an intermediate transfer member and then transferred from the intermediate transfer member to a recording material can be obtained. Of course, the image forming apparatus is not limited to a color image forming apparatus, and may be a monochrome image forming apparatus.

  As described above, the developing device, the process cartridge, and the image forming apparatus of the present invention have been described by the above-described embodiments. However, the configuration is not limited to the above-described configuration, and various modifications can be made.

1 is a schematic configuration diagram illustrating an embodiment of an image forming apparatus according to the present invention. 1 is a cross-sectional view illustrating a schematic configuration of an embodiment of a developing device according to the present invention. 1 is a top view showing a schematic configuration of an embodiment of a developing device according to the present invention. FIG. 6 is a perspective view illustrating a toner cartridge. FIG. 5A is a schematic diagram of the conveying member, and FIG. 5B is a partially enlarged view of the conveying member. 5C and 5D are perspective views showing a magnetic pole configuration in the spiral magnet. It is a figure explaining the toner charge provision property in the conventional developing device. It is a figure explaining the toner charge provision property in the developing device of the structure according to this invention. It is a schematic block diagram explaining the state which the image development apparatus inclined. It is a figure explaining the motion of the developer in the stirring chamber in the developing device of the present invention. FIG. 2 is a schematic configuration diagram illustrating an example of a process cartridge using a developing device according to the present invention. It is sectional drawing which shows schematic structure of the conventional image development apparatus. It is a top view which shows schematic structure of the conventional image development apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developer 2 Developer container 2B Partition 3 Developer sleeve (developer carrier)
4 Magnet roll (magnetic field generating means)
5 Toner Cartridge 6 Toner Supply Port 8 Supply Screw 10 Developer Concentration Detection Device 11 Magnetic Field Generating Member 12 Developing Chamber (First Transport Path)
13 Stirring chamber (second transport path)
14 First screw (first conveying member)
15 Second screw (second conveying member)
14a, 15a Rotating shaft 14b, 15b Rotating blade 16 First opening 17 Second opening 21 Primary charger 25 Fixing device 26 Cleaning device 28 Photosensitive drum (image carrier)
29 Transfer paper 30 Process cartridge 100 Image forming apparatus

Claims (6)

A developer container containing a magnetic developer;
A developer carrying member provided in the developing container, carrying and transporting the developer, and developing an electrostatic image formed on the image carrying member;
A screw member that is provided in the developer container and has a spiral rotary blade formed on a rotary shaft that is driven to rotate; and a screw member that conveys the developer toward the developer carrier;
Developer replenishing means for replenishing the developer container with replenishment developer;
In a developing device comprising:
The developing device according to claim 1, wherein the rotating blade of the screw member has a magnetic field generating member on a spiral surface on the downstream side in the developer conveying direction.   The developing device according to claim 1, wherein the magnetic field generating member is disposed in the vicinity of an outer end portion in the radial direction on the spiral surface.   The magnetic field generating member is an elongated thin plate-like magnet formed in a spiral shape, and different magnetic poles are alternately formed along the spiral surface, or a plurality of same poles are formed on the first surface of the spiral surface. The developing device according to claim 2, wherein a number of poles different from the first surface are formed on the second surface. At least in the process cartridge in which the image carrier and the developing device are integrated,
The process cartridge according to claim 1, wherein the developing device is the developing device according to claim 1. In the image forming apparatus in which the process cartridge is detachable from the image forming apparatus main body,
The image forming apparatus according to claim 4, wherein the process cartridge is a process cartridge according to claim 4. An image bearing member; a developing device that develops an electrostatic image on the image bearing member with a developer to form a visible image; and a developer replenishing unit that replenishes the developing device with a replenishing developer. In the image forming apparatus,
The image forming apparatus according to claim 1, wherein the developing device is the developing device according to claim 1.

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