JP2007011086A - Developing device, process cartridge with developing means and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of density unevenness due to insufficiency of pumping by increasing volume of a developer within a developing container. <P>SOLUTION: The developing device is equipped with a developer carrier 4-2 which conveys the developer containing a toner and a carrier and develops the latent images formed on image carriers 1a to 1d, the developing container 4-1 which houses the developer for being supplied to the developer carriers, a developer supply member 4-6 which agitates the replenished toner and developer and supplies the developer in the developing container to the developer carriers, a preset case 4-9 which houses an unused initial developer charged into the developing container, and a sealing member 4-11 which seals an aperture for charging the initial developer disposed on the developing container side of the preset case and is demountably attached in the longitudinal direction of the developer carriers at the commencement of use of the developing device, in which the preset case 4-9 is provided with at least one of magnetic field generating means 4-12 to generate the magnetic fields and is configured to enable attachment and detachment of the initial developer 4-10 adsorbed by the magnetic field generating means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a developing device that supplies toner into a developer container that contains a developer, a process cartridge including the developing means, and an image forming apparatus.
About.

  Generally, in an image forming apparatus equipped with a developing device that contains a two-component developer containing toner and a carrier, if the image is continuously output, the toner in the developer is consumed in the developing area, so that the shortage is compensated. Thus, the replenishment toner is configured to be supplied to the developing device. At this time, the replenished toner and the developer are mixed, but when this process is repeated, the toner additive adheres to the surface of the carrier, and the toner charge amount decreases, so that the toner supply is reduced. In some cases, the toner density may be reduced. As a result, the bulk of the developer is reduced, and density unevenness due to insufficient pumping may occur. Patent Document 1 describes that the initial developer is increased in advance in anticipation of a decrease in toner density over time.

JP 2003-6049 A

However, it is possible to increase the initial developer in advance in anticipation of a decrease in toner concentration over time, but if the developer concentration in the developer container exceeds the allowable amount of developer due to fluctuations in the toner concentration due to the environment, the developer dispersion This may cause a defect, fail to ensure a sufficient amount of toner charge, and may cause toner scattering or background contamination.
An object of the present invention is to increase the bulk of the developer in the developing container and suppress the occurrence of density unevenness due to insufficient pumping.

  In the developing device according to the present invention, initially, the developer capacity to be charged from the preset case is determined in consideration of the toner density fluctuation, and a part of the initial developer is adsorbed by the magnetic field generating means existing in the preset case. The initial developer adsorbed by the magnetic field generating means is released at a certain timing and the developer volume is reduced due to the decrease in toner concentration over time, increasing the developer volume in the developer container and insufficient pumping. It is possible to suppress the occurrence of density unevenness due to. That is, by providing at least one magnetic field generating means for generating a magnetic field in the preset case so that the initial developer adsorbed by the magnetic field generating means can be detached, the initial developer can be charged into the developing container over time. .

  In the developing device according to the present invention, the magnetic field generating unit is provided with a magnetically permeable member disposed between the magnetic field generating unit and the initial developer so that the initial developer is not directly adsorbed to the magnetic field generating unit. By moving it away from the magnetically permeable member, the initial developer adsorbed on the magnetically permeable member by the magnetic field generating means can be removed.

  The developing device according to the present invention includes a magnetic flux shielding member that is movably disposed between the magnetic field generating means and the initial developer and shields the magnetic field, and shields the magnetic flux between the magnetic field generating means and the initial developer. By moving the member, the initial developer adsorbed by the magnetic field generating means can be removed.

  In the developing device according to the present invention, the preset case has two rooms, one of which is provided with magnetic field generating means, and only the carrier, not the initial developer, is accommodated in the room. In addition to the developer added at the start of use, the developer and carrier are prevented from being mixed when only the carrier is added over time.

A process cartridge according to the present invention includes a developing unit having any one of the above magnetic field generating units.
An image forming apparatus according to the present invention includes a developing device or a process cartridge having any one of the above magnetic field generating means.

  According to the present invention, the preset case has at least one magnetic field generating means for generating a magnetic field, and the initial developer adsorbed by the magnetic field generating means is configured to be detachable. When it is not desired, it can be adsorbed by the magnetic field generating means, and when it is desired to be charged, it can be removed from the magnetic field generating means. Therefore, the initial developer charging timing can be adjusted, and the developer in the developing container can be adjusted. It can increase the bulk and suppress the occurrence of density unevenness due to insufficient pumping.

  According to the present invention, the initial developer accommodated in the preset case is removed from the developing container at the start of use of the developing device, so that the initial developer that is not affected by the magnetic field generating means is put into the developing container, and the magnetic field is Since the initial developer affected by the generating means remains in the preset case without being charged into the developing container, it is possible to add some initial developer over time rather than at the start of use of the developing device. Become.

  According to the present invention, the initial developer adsorbed by the magnetic field generating means is released when the bulk of the developer in the developer container is reduced due to the toner concentration reduction. By adding it, it is possible to increase the bulk of the developer and suppress the occurrence of density unevenness due to insufficient pumping.

  According to the present invention, the magnetic field generating means is provided with a magnetically permeable member disposed between the magnetic field generating means and the initial developer so that the initial developer is not directly adsorbed to the magnetic field generating means. Since the initial developer adsorbed on the magnetically permeable member by the magnetic field generating means is released by moving it away from the position, the initial developer that cannot be removed while being adsorbed on the magnetic field generating means when the initial developer is charged is eliminated. Is possible.

  According to the present invention, a magnetic flux shielding member that is movably disposed between the magnetic field generating means and the initial developer and shields the magnetic field is provided, and the magnetic flux shielding member is provided between the magnetic field generating means and the initial developer. By moving, the initial developer adsorbed by the magnetic field generating means is released, so if you do not want to put the initial developer, it is adsorbed by the magnetic field generating means, and when you want to put it, you can remove it. The initial developer charging time can be adjusted, the developer in the developer container can be increased in volume, and density unevenness due to insufficient pumping can be suppressed.

  According to the present invention, since the preset case is partitioned into two rooms by one wall, the initial developer and the carrier can be individually accommodated, and mixing of the two can be prevented.

  According to the present invention, since the magnetic field generating means is provided in one room of the preset case, and not the initial developer but only the carrier is accommodated in the room, the initial developer is charged at the start of use of the developing device, It becomes possible to introduce a carrier.

  According to the present invention, at least one unit selected from the developing unit, the image carrier, the charging unit, the developing unit, and the cleaning unit is integrally supported and is detachable from the main body of the image forming apparatus. Similarly to the case of the developing device alone, the initial developer charging timing can be adjusted, the developer in the developing container can be increased in volume, and density unevenness due to insufficient pumping can be suppressed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an example in which an endless transfer belt is used as an intermediate transfer member, and each of the photosensitive members serving as a plurality of image carriers is provided with a developing device, and a single color toner image is formed on each of the photosensitive members. Production of a color copying machine, which is an example of a so-called tandem type image forming apparatus, which sequentially transfers a single color toner image to a transfer belt and then transfers the image to a sheet as a recording material by secondary transfer and records a composite color image. The image part is shown. The image forming apparatus is not limited to a color copying machine, but may be a laser printer, a facsimile machine, or a complex machine thereof, and is not limited to a color machine.

  An image forming process of the color copying machine and an outline of its configuration will be described. In the color copying machine shown in FIG. 1, reference numeral 100 denotes an image forming apparatus main body. Inside the image forming apparatus main body 100, the photosensitive drums 1a, 1b, 1c, and 1d, which are drum-shaped image carriers on which electrostatic latent images are formed on the outer peripheral surface, and the outer peripheral surfaces of the photosensitive drums 1a to 1d are defined. Charge rollers 2a, 2b, 2c, 2d as charging means for charging to a potential, and light emitting elements 3a, 3b, 3c that serve as light sources for forming an electrostatic latent image on the outer peripheral surface charged to a specified potential by exposure. , 3d, and developing devices 4a, 4b, 4c, 4d for converting the electrostatic latent image into a visible image of toner constituting the current agent, and an intermediate transfer member that temporarily transfers the visible image formed on the outer peripheral surface. A transfer belt 5, a paper transfer belt 7 for transferring a visible image of the intermediate transfer belt 5 to a transfer paper P as a recording material, and a fixing device 8 are provided. In this embodiment, the photosensitive member, the charging unit, the developing unit, and the cleaning unit are integrally supported, and process cartridges 100a, 100b, 100c, and 100d that are detachable from the image forming apparatus main body 100 are configured. .

  Next, the operation of the entire known image forming apparatus will be described with reference to FIG. In the color copying machine, the outer peripheral surfaces of the photosensitive drums 1a to 1d, which are image carriers provided rotatably, are uniformly charged by the charging rollers 2a to 2d, and exposed to light by the light emitting elements 3a to 3d. An electrostatic latent image is formed. The electrostatic latent image is visualized as a toner image by applying non-magnetic toner constituting the current agent by the developing devices 4a to 4d. Next, the visible image is temporarily transferred (primary transfer) to the intermediate transfer belt 5 by the intermediate transfer belt means 12a, 12b, 12c, and 12d, and then transferred through the registration roller pair 6 disposed in the paper transport system. The visible image on the intermediate transfer belt 5 is transferred onto the paper P by the paper transfer belt 7. The visible image transferred to the transfer paper is conveyed by the paper transfer belt 7 and the toner image is fixed to the recording paper P by the fixing device 8 with heat and pressure to obtain a permanent image. Transfer residual toner on the photosensitive drums 1a to 1d is removed by the cleaning means 9a, 9b, 9c, and 9d. Further, the residual toner on the intermediate transfer belt 5 is removed by the intermediate transfer cleaning blade 12.

  The new toner filled in the toner bottle is replenished to the toner hopper portions 11a, 11b, 11c, and 11d disposed on the back side of the machine body by the toner replenishing devices 10a, 10b, 10c, and 10d. The toner stored in each toner hopper section is supplied with an appropriate amount of toner from the hopper to the developing device when the toner concentration detecting means (not shown) in each developing device determines that the toner concentration in each developing device is low. It is configured to be.

  FIG. 2 is a schematic cross-sectional view showing a schematic configuration of the developing device 4. Each developing device has the same configuration except that the color of the supplied toner and the color of the stored toner are different. Therefore, the developing devices will be collectively referred to as the developing device 4 here. As shown in FIG. 2, the developing device 4 is disposed to face the photosensitive drum 1, and includes a developing container 4-1, a developing sleeve 4-2 carrying a developer in the developing container 4-1, and a developing device. A blade 4-3 is provided for regulating the height of the developer carried on the sleeve 4-2.

  The developing container 4-1 is divided into a developing chamber 4-4 positioned closer to the developing sleeve 4-2 partitioned in the vertical direction, and a stirring chamber 4-5 positioned far from the developing sleeve 4-2. Yes. In the developing chamber 4-4 and the stirring chamber 4-5, a developer (two-component developer) containing a non-magnetic toner (hereinafter referred to as toner) and a magnetic carrier (hereinafter referred to as carrier) is accommodated. The developer in the developing chamber 4-4 and the stirring chamber 4-5 is circulated.

  The developing chamber 4-4 and the agitating chamber 4-5 are respectively parallel to the developing sleeve 4-2 for agitating and conveying the developer and toner in the developer container and supplying the developer to the developing roller. , A rotatable developer agitating / conveying means 4-6 (hereinafter referred to as a first screw 4-6) and a developer agitating / conveying in a direction parallel to the first screw 4-6 and opposed thereto. A rotatable second developer agitating / conveying means 4-7 (hereinafter referred to as a second screw 4-7) for circulating the developer is disposed.

  The developing sleeve 4-2 is made of a non-magnetic material, and a magnet 4-8 that generates a magnetic field is fixedly disposed therein. A developing sleeve 4-2 having a built-in magnet 4-8 carries and conveys a layer of a two-component developer whose layer thickness is regulated by a blade 4-3 to the developing area and sensitizes toner in the developing area facing the photosensitive drum 1. The electrostatic latent image formed on the photosensitive drum 1 is developed by being supplied to the drum 1.

  Further, the developing device 4 is provided with a preset case 4-9 for storing an unused initial developer 4-10 to be put into the developing container 4-1, and when the developing device 4 starts to be used, The initial developer 4-10 is removed from the developing container by removing the seal member 4-11, which closes the opening for introducing the initial developer provided on the developing container side, in the longitudinal direction of the developing device 4 as shown in FIG. 4-1.

  Next, a schematic configuration of a preset case 4-9 provided with magnetic field generation means 4-12 such as a permanent magnet that generates a characteristic magnetic field of the present embodiment will be described with reference to FIGS. As shown in FIGS. 3 and 4 above the stirring chamber 4-5 in FIG. 2, the magnetic field generating means 4-12 is disposed at the end of the preset case 4-9.

  With this configuration, the initial developer 4-10 accommodated in the preset case 4-9 can be removed from the magnetic field generating unit 4-12 by removing the seal member 4-11 at the start of use of the developing device 4. The initial developer 4-10-1 that is not affected is charged into the developing container 4-1, and the initial developer 4-10-2 that is affected by the magnetic field generating means 4-12 is charged into the developing container 4-1. Without staying in the preset case 4-9. Then, when the volume of the developer in the developer container 4-1 is reduced due to the decrease in the toner concentration over time, the initial developer 4-10-2 adsorbed by the magnetic field generating unit 4-12 is released, Occurrence of density unevenness due to insufficient pumping caused by a decrease in the bulk of the developer over time can be suppressed.

  Another embodiment will be described with reference to FIGS. A partition plate 4-13 serving as a wall is provided in the preset case 4-9 to divide it into two chambers, and a magnetic field generating means 4-12 is provided only in one of the chambers. -14 is accommodated, and the magnetic field generating means 4-12 is not provided in another room, and the initial developer 4-10 is accommodated before the start of use of the developing device 4 by accommodating the initial developer 4-10. 4-14 is not mixed. Further, by removing the seal member 4-11 at the start of use of the developing device 4, the initial developer 4-10 in the room without the magnetic field generating unit 4-12 is charged into the developing container 4-1, and the magnetic field generating unit 4- The carrier 4-14 in the room in which the housing 12 is provided is not put into the developing container 4-1, but remains in the preset case 4-9.

  Next, means for detaching the initial developer 4-10-2 adsorbed by the magnetic field generating means 4-12 or the carrier 4-14 will be briefly described with reference to FIGS. As shown in FIGS. 7 to 12, a magnetically permeable member 4-15 is provided between the magnetic field generating means 4-12 and the initial developer 4-10-2 so that they are not directly adsorbed. Then, in order to release the adsorbed initial developer 4-10-2, the magnetic field generating means 4-12 is moved upward as indicated by arrow A as shown in FIG. 8, or as shown in FIGS. Thus, the magnetic field generating means 4-12 is supported by a shaft so that it can be rotated or turned in the direction of arrow B, or a magnetic flux shielding member 4-16 is placed on the magnetically permeable member 4-15 as shown in FIGS. The magnetic flux shielding member 4-16 may be moved in the arrow C direction as appropriate.

  With this configuration, when the initial developer 4-10-2 is not desired to be charged, it can be adsorbed by the magnetic field generating means 4-12, and when it is desired to be charged, the magnetic field generating means 12 can be rotated. What is necessary is just to detach | leave by moving the magnetic flux shielding member 4-16. These magnetic field generating means 4-12 rotate and rotate, and the magnetic flux shielding member 4-16 moves by operating a known drive source such as a motor or electromagnetic solenoid by operating a control switch (not shown) provided on the operation panel of the color copying machine. It may be arbitrarily driven, or may be appropriately driven according to the output from the toner density sensor.

1 is an enlarged view showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view showing a schematic configuration of a developing device. It is a perspective view which shows schematic structure of the preset case which is the 1st characteristic part of this invention. It is a perspective view which shows the state which removed the sealing member from the preset case shown in FIG. It is a perspective view which shows schematic structure of the preset case partitioned off by the wall which is the 2nd characteristic part of this invention. It is a perspective view which shows the state which removed the sealing member from the preset case shown in FIG. It is the schematic which shows schematic structure of the preset case provided with the magnetic permeability member which is the 3rd characteristic part of this invention. It is the schematic which shows one form of a movement of the magnetism generation member in the preset case shown in FIG. It is the schematic which shows schematic structure of the preset case which supported the magnetism generating member which is the 4th characteristic part of this invention rotatably. FIG. 10 is a schematic view when the magnetism generating member is rotated in the preset case shown in FIG. 9. It is the schematic which shows schematic structure of the preset case provided with the magnetism generating member and magnetic flux shielding member which are the 5th characteristic parts of this invention. It is a schematic block diagram when a magnetic flux shielding member is moved in the preset case shown in FIG.

Explanation of symbols

Developer containing toner and carrier 1a to 1d Image carrier 4, 4a to 4d Developing device 4-1 Developer container 4-2 Developer carrier 4-7 Developer supply member 4-9 Preset case 4-10 Initial development Agent 4-11 Seal member 4-12 Magnetic field generating means 4-13 Wall 4-14 Carrier 4-15 Magnetic permeable member 4-16 Magnetic flux shielding member 2a to 2d Charging means 9a to 9d Cleaning means 100a to 100d Process cartridge

Claims (11)

A developer carrying member that transports a developer containing toner and a carrier to develop a latent image formed on the image carrying member; a developer container that contains a developer to be supplied to the developer carrying member; A developer supply member that stirs the replenished toner and developer and supplies the developer in the developer container to the developer carrier, and a preset that stores unused initial developer to be charged into the developer container A case, and a seal member that seals an opening for initial developer charging provided on the developer container side of the preset case and is detachably attached in the longitudinal direction of the developer carrier when starting to use the developing device. In the developing device provided,
2. A developing apparatus comprising: at least one magnetic field generating means for generating a magnetic field in the preset case, wherein the initial developer adsorbed by the magnetic field generating means can be detached.   The initial developer housed in the preset case is removed from the seal member at the start of use of the apparatus, so that the initial developer that is not affected by the magnetic field generating means is put into the developing container, and the magnetic field generating means The developing device according to claim 1, wherein the affected initial developer remains in the preset case without being charged into the developing container.   3. The developing device according to claim 1, wherein when the volume of the developer in the developer container is reduced due to a decrease in toner concentration, the initial developer adsorbed by the magnetic field generating unit is released. A magnetically permeable member disposed between the magnetic field generator and the initial developer so that the initial developer is not directly adsorbed to the magnetic field generator;
4. The initial developer adsorbed on the magnetically permeable member by the magnetic field generating means is released by moving the magnetic field generating means to a position away from the magnetically permeable member. The developing device described. A magnetic flux shielding member that is movably disposed between the magnetic field generating means and the initial developer and shields the magnetic field;
5. The initial developer adsorbed by the magnetic field generating means is released by moving the magnetic flux shielding member between the magnetic field generating means and the initial developer. The developing device described.   6. The developing device according to claim 1, wherein the magnetic field generating unit is a permanent magnet.   The developing device according to claim 1, wherein the preset case has one wall and has two rooms partitioned by the wall.   8. The developing device according to claim 7, wherein the magnetic field generating unit is provided in one room of the preset case, and only the carrier is accommodated in the room.   A process cartridge that integrally supports at least one unit selected from a developing device, an image carrier, a charging unit, a developing unit, and a cleaning unit and is detachable from the main body of the image forming apparatus as the developing unit. 9. A process cartridge on which the developing device according to claim 8 is mounted.   An image forming apparatus comprising the process cartridge according to claim 9.   An image forming apparatus comprising the developing device according to claim 1.

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