Electrophotography – Image formation – Development
Reexamination Certificate
2000-09-15
2002-05-14
Royer, William J. (Department: 2852)
Electrophotography
Image formation
Development
C399S263000
Reexamination Certificate
active
06389257
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a developing cartridge used in an image forming apparatus such as a printer apparatus, a copying machine, a facsimile machine or the like to which an electrophotographic system is applied, and more particularly to a developer cartridge having a spirally-formed feeding member mounted in a cylindrical member.
2. Description of the Related Art
In a conventional image forming apparatus, such as a full color printer apparatus or the like, to which an electrophotographic system is applied, normally three developers for developing electrostatic latent images with three primary color developers of Y (yellow), M (magenta) and C (cyan), preferably four developers containing the above three developers and a black color developer for developing an electrostatic latent image with black (K) developer are mounted so that one of these plural color developers is selectively disposed in the neighborhood of an electrostatic latent image carrier or each of these plural developers is disposed in the neighborhood of each of plural electrostatic latent image carriers corresponding to the respective color developers, and an electrostatic latent image formed on the single electrostatic latent image carrier or electrostatic latent images formed on the plural electrostatic latent image carrier are successively visualized by the corresponding color developers, thereby forming a full color image.
When attributing importance to the compact size of the apparatus or reduction of the cost of the apparatus in the above full color image forming apparatus, though an image forming speed slows down a little, the method of selectively disposing one of the plural developers in the neighborhood of the single electrostatic latent image carrier is adopted. The inventors of this application have tackled to implement such an image forming apparatus that a rotator having four developers disposed along the peripheral direction thereof is rotatably disposed, and when an electrostatic latent image formed on an electrostatic latent image carrier is developed by each developer, the rotator is rotated so that a desired color developer is disposed so as to confront the electrostatic latent image carrier.
In a full color image forming apparatus being considered by the inventors, a system using a toner cartridge is adopted to supplement toner to each developer. The toner cartridge is detachably mounted in the developer, and it is designed so that an operator of the image forming apparatus replaces a toner cartridge with a new one when all the toner in the toner cartridge concerned is consumed.
As the toner cartridge as described above is proposed a toner cartridge using a so-called “trickle developing system” which is called by the inventors of this application and in which developer containing at least toner is supplied from the toner cartridge concerned to the developer and deteriorated developer is withdrawn from the developer into the toner cartridge little by little. This type toner cartridge using the trickle developing system has been introduced into actual machines.
In the toner cartridge using the “trickle developing system”, a withdrawing unit for stocking old developer thus withdrawn is disposed at the end portion of the toner cartridge concerned. This toner cartridge is generally designed so that a rotational fixing portion of an agitator for supplying new developer is provided at a toner cap side in order to minimize the volume of the withdrawing portion for the old developer and increase the volume of the stock portion for the new developer.
However, the above conventional technique has the following problems. That is, in the case of the conventional toner cartridge as described above, the rotational fixing portion of the agitator for supplying new developer is provided at the toner cap side, and thus after developer containing at least toner is filled into the toner cartridge, the agitator which has been mounted in the toner cartridge must be fitted to the driving portion of the toner cap at the same time when the toner cap is mounted into the main body of the toner cartridge, so that it is very difficult to perform a toner cap mount work.
Furthermore, in the case of the above conventional toner cartridge, when toner is filled into the toner cartridge in such a state that the agitator is disposed in the toner cartridge, air is contaminated into toner to reduce the apparent density of the toner and thus reduce the substantial toner fill amount per unit time, so that the working efficiency of filling the toner into the toner cartridge is reduced.
Still furthermore, in the case of the above conventional toner cartridge, a so-called one-side supported type toner cartridge in which an agitator for feeding toner is supported only at the toner cap side is used. In this case, in connection with recent requirements of enhancing image quality and designing the apparatus in compact size, the toner particle size is reduced and toner containing wax which enables elimination of oil as separating agent in the fixer is used. In this case, there may occur such a problem that the toner particles aggregate together to form lumps of toner due to the slight rubbing between the agitator and the inner wall of the toner cartridge, and these lumps of toner are developed to induce degradation of image quality.
In addition, in the case of a toner cartridge using a so-called one-side supported type agitator, the rotational torque for rotating the agitator is increased due to the rubbing between the agitator and the inner wall of the toner cartridge, the eccentric rotation of the agitator or the like, so that a driving device for rotating the agitator must be designed in large size.
Therefore, in order to solve the above problems, it may be considered that a so-called double-side supported type agitator in which both the end portions of an agitator are supported is used in place of the so-called one-side supported type agitator.
However, even when the double-side supported type agitator is used, there is still such a problem that the center portion of the agitator may interfere in the inner wall of the toner cartridge due to warp caused by the agitator's own weight, warp caused by the press force of the toner particles, or warp caused by centrifugal force occurring during rotation or at acceleration occurring at the stop time of the rotation in the case of a rotational type developing apparatus.
Furthermore, in order to enhance the fill efficiency of the toner, it is necessary to mount an agitator in a toner cartridge after toner is filled in the toner cartridge. However, in this case, it is required that the agitator is mounted in the toner cartridge after the toner is filled in the toner cartridge, and also the tip portion of the agitator is fitted into the bearing portion. According, there is such a problem that the tip portion of the agitator may not be surely fitted into the bearing portion due to a failure of fitting, and thus a defective toner cartridge is liable to be produced.
In addition, when the agitator is mounted after the toner is filled in the toner cartridge, there occurs such a new problem that the toner is trapped at the bearing portion in the toner cartridge and thus the agitator cannot be inserted into the bearing portion.
Furthermore, in order to avoid the trap of the toner at the bearing portion, it is considered that a toner escaping hole is provided to the bearing portion. However, if the position of the toner escaping hole is improper, the toner rather invades into the bearing portion, and lumps of toner are formed in the bearing portion by rotation of the agitator shaft. The lumps of toner thus formed in the bearing portion leak from the escaping hole, and induce defects in image quality.
Still furthermore, in the case of the so-called double-side supported type agitator, when the agitator is mounted after the toner is filled in the toner cartridge, there occurs such a new problem that it cannot be judged by a visual check or
Harumoto Katsumi
Masubuchi Toshio
Fuji 'Xerox Co., Ltd.
Morgan & Lewis & Bockius, LLP
Royer William J.
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