JP2006163238A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of suppressing a deterioration in image quality at low cost. <P>SOLUTION: The developing device includes a developer carrier which circulates through a supply region where magnetic toner is supplied to the surface, a toner layer formation region where the magnetic toner supplied to the surface is formed into a toner layer with a designated thickness, and a development region where an electrostatic latent image formed on an image carrier is developed with magnetic toner of the toner layer, a fixed magnet which has a plurality of magnetic poles fixedly arranged on the reverse surface side of a developer carrier in the moving direction of the developer carrier and magnetically attracts the magnetic toner, a storage chamber which is arranged nearby the supply region and contains the magnetic toner to be sent in the supply region, and a magnet member which faces a specific magnetic pole arranged in the region between the development region and toner layer formation region in the moving direction of the developer carrier among the plurality of magnetic pole from the side of the developer carrier surface and produces a repulsing magnetic field, restricting entry of magnetic toner sent in from the storage chamber into the supply region, with the specific magnetic pole. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is provided with a developing device that is arranged to face an image carrier on which an electrostatic latent image is formed and develops the electrostatic latent image formed on the image carrier with magnetic toner, and the developing device. The present invention relates to an image forming apparatus.

  Conventionally, as a developing device used in an image forming apparatus such as a printer or a copying machine, it is provided opposite to a photoreceptor roll on which an electrostatic latent image is formed, and is made of aluminum or stainless steel on the surface as required. Magnetic toner carried on the surface of a cylindrical sleeve having irregularities on its surface by means such as sandblasting is conveyed by rotating the sleeve to a development area formed between the photosensitive roll and the toner electrostatically. In particular, it is known to develop an electrostatic latent image formed on the surface of the photoreceptor roll by transferring it to the photoreceptor roll side.

  However, in the developing device having such a sleeve, the toner on the lowermost layer portion of the sleeve surface cannot properly charge the toner on the upper layer, for example, by a layer thickness regulating member, and the density is reduced. There is a problem that image defects such as so-called development ghosts are likely to occur.

  The toner adhering to the sleeve surface is caused by overcharging due to contact with the charging member many times by rotation of the sleeve, and firmly adhering to the sleeve surface by electrostatic force. It has been reported that many particles have a small particle size.

  In view of this, a proposal has been made to suppress the residual of small-diameter toner by forming the sleeve surface with a resin film containing conductive fine powder (see Patent Document 1).

  According to this proposal, the support of the toner particles is ensured by using a resin coating, and the toner particles adhering to the sleeve are excessively discharged by discharging electric charges to the sleeve side by the conductive fine powder contained in the resin. Charging is suppressed.

However, in this case, the leakage of electric charge becomes severe under high temperature and high humidity, and on the contrary, the charge imparting property to the toner is lowered, and image defects such as density reduction due to the toner being too low are likely to occur. There's a problem.
JP-A-1-276174

  Therefore, it is conceivable to use a toner having a small proportion of small toner particles in the toner particle size distribution.

  However, there is a problem that the manufacturing cost of the toner becomes enormous.

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a developing device and an image forming apparatus that can suppress a decrease in image quality at low cost.

In order to achieve the above object, the developing device of the present invention comprises:
In a developing device that is arranged to face an image carrier on which an electrostatic latent image is formed and develops the electrostatic latent image formed on the image carrier with magnetic toner,
A supply area where magnetic toner is supplied to the surface, a toner layer formation area where the magnetic toner supplied to the surface is formed on a toner layer of a predetermined thickness, and an electrostatic latent image formed on the image carrier are A developer carrying member that circulates through a developing region that is developed by magnetic toner in the toner layer;
A fixed magnet that magnetically attracts magnetic toner by a plurality of magnetic poles fixedly arranged on the back side of the developer carrier in the moving direction of the developer carrier;
A storage chamber that is disposed in the vicinity of the supply region and stores magnetic toner to be fed to the supply region, and of the plurality of magnetic poles, the developing region and the toner layer forming region are viewed in the moving direction of the developer carrier. It faces the predetermined magnetic pole arranged in the area between them from the developer carrier surface side, and restricts the magnetic toner sent from the storage chamber from entering the supply area between the predetermined magnetic pole and the predetermined magnetic pole. A magnet member for forming a repulsive magnetic field is provided.

  In the developing device of the present invention, the predetermined magnetic pole disposed in the region between the developing region and the toner layer forming region, as viewed in the moving direction of the developer carrying member, and the predetermined magnetic pole facing the developer carrying member from the surface side. The repulsive magnetic field generated between the predetermined magnetic pole and the magnet member having the same polarity restricts the magnetic toner sent from the storage chamber from entering the supply area. As a result, the toner in the storage chamber is suppressed from being excessively fed into the supply region. When the toner is excessively fed to the supply area, new toner is always sent to the area between the development area and the supply area (area D in FIG. 2) in the moving direction of the developer carrier. It becomes. On the other hand, on the developer carrier, the developer having a relatively small particle size in the toner particle size distribution adheres firmly to the surface of the developer carrier (the lower layer in the developer layer) by rotating. However, when new toner is always supplied to the developer carrier as described above, the small particle size toner that easily adheres to the surface of the developer carrier is always carried by the developer. As a result, the particle size reduction on the surface of the developer carrying member is further accelerated. As a result, problems such as image density reduction and development ghost are caused. Therefore, according to the developing device of the present invention, it is possible to suppress the strong adhesion of the magnetic toner having a small particle diameter to the surface of the developer carrying member by providing the magnet member. A reduction in image quality can be suppressed at a low cost.

Here, the agitator that feeds the magnetic toner contained in the accommodation chamber toward the supply area by rotating, and the magnetic toner that is fed by the rotation of the agitator connected to the supply area passes therethrough. With an opening,
Preferably, the magnet member generates a repulsive magnetic field in the vicinity of the opening that restricts the magnetic toner sent from the storage chamber through the opening to the supply area and entering the supply area. Alternatively, it is also a preferable aspect that the magnet member is opposed to the magnetic pole disposed in the region adjacent to the toner layer forming region on the upstream side in the moving direction from the surface of the developer carrying member. .

  In this way, it is possible to prevent the toner in the storage chamber from entering the excessive supply region, thereby effectively suppressing the strong adhesion of the small particle size toner to the surface of the developer carrying member. it can.

In order to achieve the above object, an image forming apparatus of the present invention comprises:
A developing device is provided opposite to the image carrier on which the electrostatic latent image is formed, and develops the electrostatic latent image formed on the image carrier with magnetic toner. The electrostatic latent image is developed using the developing device to form a toner image on the image carrier, and the toner image is finally transferred and fixed on a predetermined recording medium. In an image forming apparatus for forming an image composed of a fixed toner image,
The developing device is
A supply area where magnetic toner is supplied to the surface, a toner layer formation area where the magnetic toner supplied to the surface is formed on a toner layer of a predetermined thickness, and an electrostatic latent image formed on the image carrier are A developer carrying member that circulates through a developing region that is developed by magnetic toner in the toner layer;
A fixed magnet that magnetically attracts magnetic toner by a plurality of magnetic poles fixedly arranged on the back side of the developer carrier in the moving direction of the developer carrier;
A storage chamber that is disposed in the vicinity of the supply region and stores magnetic toner to be fed to the supply region, and of the plurality of magnetic poles, the developing region and the toner layer forming region are viewed in the moving direction of the developer carrier. A repulsive magnetic field that opposes the predetermined magnetic pole disposed between the developer carrier surface side and restricts the magnetic toner fed from the storage chamber from entering the supply region between the predetermined magnetic pole and the predetermined magnetic pole. It is provided with the magnet member which forms.

  According to the developing device and the image forming apparatus of the present invention, it is possible to suppress image quality degradation such as image density degradation and development ghost at low cost.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention including an embodiment of a developing device according to the present invention.

  The printer 1 shown in FIG. 1 is an electrophotographic image forming apparatus for monochrome images that is covered with a housing 10.

  The printer 1 includes a paper feeding unit 20, a paper transport unit 30, an image forming unit 40, and a fixing unit 50. The image forming unit 40 includes an exposure device 41, a transfer roll 42, a photoconductor roll 43, a charging unit. A roll 44, a developing roll 45, and a toner cartridge 46 are included.

  The paper feed unit 20 includes a paper feed tray 21 and a pickup roll 22, and the paper transport unit 30 includes a transport path 31, a feed roll 32, a transport roll 33, and a discharge roll 34. The fixing unit 50 includes a heating roll 51 and a pressure roll 52, which are not related to the present invention, and thus detailed description thereof is omitted.

  FIG. 2 is an enlarged view of the toner cartridge.

  In the toner cartridge 46 shown in FIG. 2, a magnetic toner 50 agitated by an agitator 49 that rotates in the direction of the arrow Z is fed into the toner storage chamber 461 through the opening 462 toward the developing roll 45, and the toner storage chamber 461. A toner supply chamber 463 that accommodates the magnetic toner 50 to be supplied, and a layer thickness regulating member 47 that applies a charge due to frictional charging to the magnetic toner carried on the surface of the developing roll 45 and regulates the layer thickness. .

  2 is provided with a developing roll 45 that carries the magnetic toner 50 on the surface thereof. The developing roll 451 has a sleeve 451 that is rotatable while carrying the magnetic toner 50 on the surface. The magnet sleeve 452 is fixed to the toner cartridge 46 inside the rotatable sleeve 451.

  The sleeve 451 rotates in a direction indicated by an arrow Y, a supply area A where the magnetic toner 50 is supplied to the surface, a toner layer formation area B where the magnetic toner 50 supplied to the surface is formed in a toner layer having a predetermined thickness. The electrostatic latent image formed on the surface of the photoreceptor roll 43 that rotates is rotated in the direction of arrow X via the developing area C where the magnetic toner 50 of the toner layer is developed.

  The magnet roll 452 magnetically attracts the magnetic toner 50 having four magnetic poles 453a, 453b, 453c, and 453d fixedly arranged.

  Further, in the toner cartridge 46 shown in FIG. 2, a repulsive magnetic field that restricts the magnetic toner 50 fed from the toner storage chamber 461 through the opening 462 to the supply area A to enter the supply area A is provided in the opening 462. The polarity of the magnetic pole 453d from the surface side of the sleeve 451 (S pole) is the same as that of the magnetic pole 453d arranged in the toner supply area A that is adjacent to the toner layer forming area B on the upstream side in the rotation direction. There is provided a magnet member 48 arranged to face a magnetic pole (S pole) having a polarity.

  In the printer 1 of the present embodiment, as described above, of the four magnetic poles arranged on the magnet roll 452, the magnetic pole 453d disposed in the supply region A adjacent to the toner layer forming region B on the upstream side in the rotation direction. The repulsive magnetic field formed in the vicinity of the opening 462 by the magnet member 48 limits the amount of toner supplied from the toner storage chamber 461 to the developer carrier 45 by the rotation of the agitator 49. Thereby, it is suppressed that the small particle size toner that easily adheres firmly to the developer carrier 45 is supplied indefinitely. Therefore, according to the printer 1 of the present embodiment, the image quality deterioration caused by the small particle size toner firmly adhering to the surface of the sleeve 451 is used, such as the toner from which the small particle size is removed. That is, it can be suppressed at low cost.

  In the embodiment described above, the repulsive magnetic field that restricts the entry of the magnetic toner 50 fed from the toner storage chamber 461 through the opening 462 into the supply area A into the supply area A is used as the toner supply area A. The magnetic member 48 disposed opposite to the magnetic pole 453d is provided to be generated in the vicinity of the opening 462. However, in the present invention, the developing region is viewed in the rotational direction of the sleeve 451. Supply region of the magnetic toner 50 that is opposed to the predetermined magnetic pole disposed in the region between C and the toner layer forming region B from the surface side of the sleeve and is fed from the toner storage chamber 461 between the predetermined magnetic pole. Any magnet member that forms a repulsive magnetic field that restricts entry into A may be used, and the magnetic pole 453d disposed in the toner supply region A may also be closer to the upstream side in the rotation direction of the sleeve 451. Or it may be provided with a magnet member which faces the location pole 453c.

1 is a schematic configuration diagram of an embodiment of an image forming apparatus of the present invention including an embodiment of a developing device of the present invention. FIG. 3 is an enlarged view of a toner cartridge.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printer 20 Paper feed part 30 Paper conveyance part 40 Image formation part 41 Exposure device 42 Transfer roll 43 Photoconductor roll 44 Charging roll 45 Development roll 451 Sleeve 452 Magnet roll 453a, 453b, 453c, 453d Magnetic pole 46 Toner cartridge 461 Toner storage chamber 462 Opening 463 Toner supply chamber 47 Layer thickness regulating member 48 Magnet member 49 Agitator

Claims (4)

In a developing device that is arranged to face an image carrier on which an electrostatic latent image is formed and develops the electrostatic latent image formed on the image carrier with magnetic toner,
A supply area where magnetic toner is supplied to the surface, a toner layer formation area where the magnetic toner supplied to the surface is formed on a toner layer of a predetermined thickness, and an electrostatic latent image formed on the image carrier A developer carrying member that circulates through a developing region that is developed by magnetic toner in the toner layer;
A fixed magnet that magnetically attracts magnetic toner with a plurality of magnetic poles fixedly arranged on the back surface side of the developer carrier in the moving direction of the developer carrier;
A storage chamber that is disposed in the vicinity of the supply region and that stores magnetic toner to be fed to the supply region; and, among the plurality of magnetic poles, the developing region and the toner layer forming region as viewed in the moving direction of the developer carrier. It faces the predetermined magnetic pole arranged in the area between them from the developer carrier surface side, and restricts the magnetic toner sent from the storage chamber to the supply area between the predetermined magnetic pole and the predetermined magnetic pole. A developing device comprising a magnet member for forming a repulsive magnetic field. An agitator that feeds the magnetic toner contained in the storage chamber toward the supply region by rotating, and an opening that is connected to the supply region and through which the magnetic toner sent out by rotation of the agitator passes. Have
The magnet member generates a repulsive magnetic field in the vicinity of the opening for restricting the magnetic toner sent from the storage chamber through the opening to the supply area to enter the supply area. The developing device according to claim 1.   2. The developer carrying member surface side, wherein the magnet member is opposed to a magnetic pole disposed in a region adjacent to the toner layer forming region on the upstream side in the moving direction. Development device. A developing device is provided opposite to the image carrier on which the electrostatic latent image is formed, and develops the electrostatic latent image formed on the image carrier with magnetic toner, and the static image formed on the image carrier. The electrostatic latent image is developed using the developing device to form a toner image on the image carrier, and the toner image is finally transferred and fixed on a predetermined recording medium to thereby form the toner image on the recording medium. In an image forming apparatus for forming an image composed of a fixed toner image,
The developing device is
A supply area where magnetic toner is supplied to the surface, a toner layer formation area where the magnetic toner supplied to the surface is formed on a toner layer of a predetermined thickness, and an electrostatic latent image formed on the image carrier A developer carrying member that circulates through a developing region that is developed by magnetic toner in the toner layer;
A fixed magnet that magnetically attracts magnetic toner with a plurality of magnetic poles fixedly arranged on the back surface side of the developer carrier in the moving direction of the developer carrier;
A storage chamber that is disposed in the vicinity of the supply region and that stores magnetic toner to be fed to the supply region; and, among the plurality of magnetic poles, the developing region and the toner layer forming region as viewed in the moving direction of the developer carrier. A repulsive magnetic field that opposes the predetermined magnetic pole disposed between the developer carrier surface side and restricts the magnetic toner fed from the storage chamber from entering the supply region between the predetermined magnetic pole and the predetermined magnetic pole. An image forming apparatus comprising a magnet member for forming a film.

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