Electrophotography – Internal machine environment – Particle or contaminant control
Reexamination Certificate
2002-06-07
2004-02-03
Lee, Susan S.Y. (Department: 2852)
Electrophotography
Internal machine environment
Particle or contaminant control
C399S259000, C399S260000
Reexamination Certificate
active
06687474
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Japanese application serial no. 2001-174776, filed on Jun. 8, 2001.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to an image formation apparatus, such as a copy machine, a printer or a FAX machine, and a developing apparatus and a process cartridge that are used in the image formation apparatus. More specifically, the invention relates to a developing apparatus, and an image formation apparatus and a process cartridge having the developing apparatus, wherein the developing apparatus has a self toner concentration controlling machine capable of controlling the toner concentration in the developer on a developer carrier within a preset range, by using a two-component developer containing toner and magnetic carrier, and without using a complicated toner supply device.
2. Description of Related Art
One of the conventional developing apparatuses is disclosed by Japanese Laid Open H09-22179. In the developing apparatus, the amount of the developer is regulated by a developer-regulating unit, wherein the developer is carried on a developer carrier having a magnetic field generating device therein. The developer collected by the developer-regulating unit is contained in a developer container. From the toner supply gate, that is opposite to the developer carrier and is adjacent to the upstream side of the developer transfer direction in the developer container, the toner in the toner container is supplied to the developer on the developer carrier. In the developing apparatus, the toner, in contact with the developer that is carried and transferred on the developer carrier at the toner supply gate, is taken into the developer from an interface between the transferred developer and the developer contained in the developer container. As the toner concentration of the developer in the developer increases, because the volume of the developer increases, the developer contained in the developer container extends so as to cover the toner supply gate, thereby the feeding of the developer from the toner container at the toner supply gate to the developer can be suppressed. In this way, the toner concentration of the developer in the developer carrier can be controlled within a preset range. In addition, Japanese Laid Open H09-197833 discloses a developing apparatus, in which a second developer-regulating unit with a preset gap with respect to the surface of the developer carrier is set between the developer container and the toner supply gate of the toner container. In the developing apparatus, as the toner concentration of the developer in the developer carrier increases, the thickness of the developer increases. The passing of the increased developer is regulated by the second developer-regulating unit. The regulated developer covers the toner supply gate that is adjacent to the upstream side of the developer transfer direction with respect to the second developer-regulating unit, so that the feeding of the toner from the toner container to the developer carried and transferred on the developer carrier can be suppressed. Thereby, the toner concentration of the developer in the developer carrier can be controlled within a preset range.
According to the above developing apparatus to control the toner concentration of the developer in the developer carrier within a preset range (self toner concentration control), because the toner concentration sensor is not required and the stirring device such as a paddle screw etc can be omitted, the toner supply device can be simplified. Furthermore, in comparison with the conventional two-component developing method, the magnetic carrier can be reduced and the torque of the developing apparatus can be significantly reduced. As a result, the device can become smaller and more compact, and the cost can be reduced. Moreover, because the toner in the toner container can be directly supplied to the developer in the developer carrier passing through the developing area, the toner can be quickly supplied to a portion of the developer where the toner concentration decreases. Therefore, the forming ability for the black solid image is excellent.
In comparison with the conventional two-component developing method, in the developing apparatus that performs the self toner concentration control by only a few magnetic carriers, because the initial developer has to be uniformly set in the developer carrier, an initial developer container is installed in the vicinity of the developer container, and at the beginning of use, the user strips off a sealing material that separates the initial developer container from the developer container, so that the initial developer is filled into the initial developer container. In addition, in order to prevent the toner from acuminating in the toner supply unit with a toner supply gate near the developer carrier and to prevent the toner from scattering out of the toner container, a sealing material is installed for separating the toner container from the toner supply unit. This sealing material will be also stripped off by the user at the beginning of use. After the sealing material is stripped off, the developing apparatus is set into the printer, and then the toner supply unit installed in the developer carrier and the toner container rotates via gears at the same time. Then, it begins to send the initial developer to the developer carrier or begins to supply the toner to the toner supply unit.
However, at the location to strip off the sealing materials, in order to maintain a working space for stripping off the sealing materials in the longitudinal direction of the developing apparatus, i.e., the central axis line of the developer carrier, it happens that the sealing materials are stripped off under a condition that the developing apparatus is tilt. When the sealing materials are stripped off under a condition that the developing apparatus is tilt, the initial developer in the initial developer container moves to one end along the central axis line of the developer carrier, which causes the initial developer to be not uniformly set on the developer carrier along the central axis line of the developer carrier. Therefore, the toner will be over supplied to the insufficient developer area having little developer, and therefore as the toner concentration increases, abnormal image due to contamination occurs. In contrast, the developer will be scattered in the developer area having much developer. In addition, in the developing apparatus, because no stirring mechanism is provided to cycle the developer along the central axis line of the developer carrier and to stir the developer, once the initial developer is not uniformly set, the non-uniform developer problem cannot be solved, so that the abnormal image due to contamination or the developer scatter continuously occurs.
SUMMARY OF THE INVENTION
According to the foregoing description, an object of this invention is to provide a developing apparatus, an image formation apparatus and a process cartridge, by which even though the sealing material is installed on the initial developer throwing opening of the initial developer container under a condition where the developing apparatus is tilt, the initial developer can be uniformly supplied along the central axis line of the developer carrier.
According to the object(s) mentioned above, the invention provides a developing apparatus, comprising a developer carrier, a developer regulating unit, a developer container, a toner container, an initial developer container, and a sealing material. The developer carrier has a magnetic field generating device therein, for carrying a developer containing a toner and a magnetic carrier and transferring the developer to move on a surface of the developer carrier. The developer regulating unit is used for regulating an amount of the developer that is carried on the developer carrier and transferred towards a developing area. The developer container is used for containing the devel
Matsumoto Kentaroh
Nagashima Hiroyuki
Ohjimi Tokuya
Yamada Masahiko
Gleitz Ryan
Lee Susan S.Y.
Oblon, Spivak, McClelland, Maier & Neustadt PC
Ricoh & Company, Ltd.
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