Electrophotography – Having particular structure – Modular or displaceable
Reexamination Certificate
2001-11-15
2003-05-20
Grainger, Quana M. (Department: 2852)
Electrophotography
Having particular structure
Modular or displaceable
C399S359000
Reexamination Certificate
active
06567631
ABSTRACT:
This nonprovisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 2000-358247 filed in Japan on Nov. 24, 2000, which is herein incorporated by reference.
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a toner cartridge for storing fresh toner for development therein, and attached to, and used for, a developing unit of an image forming apparatus such as a copier, printer, facsimile machine and the like. More detailedly, the invention is directed to a toner cartridge wherein a collecting chamber for collecting untransferred toner left over on the photoconductor surface after transfer of toner images is arranged on one side of the storage chamber of the fresh toner, as well as relating to an image forming apparatus using this toner cartridge.
(2) Description of the Prior Art
Image forming apparatus such as a copier, printer, facsimile machine and the like form images by an exposure step where exposing the surface of a photoconductor such as a photoconductor drum, photoconductor belt or the like, to light forms a desired electrostatic latent image, a development step for making the thus formed static latent image visible with toner, a transfer step for transferring the formed toner image to the predetermined paper and a fixing step for fixing the transferred toner image on the paper with heat. The exposure, development and transfer steps are sequentially performed by the exposure unit, developing unit and transfer unit, respectively, all being arranged around the photoconductor.
The developing unit has a developer roller which is closely opposed to the photoconductor surface and rotates about an axis parallel to that surface. The toner for development is adapted to uniformly adhere to the whole surface of the developer roller on the side opposite to the photoconductor, is conveyed by the rotation of the developer roller and attracted to the latent image on the photoconductor surface by the function of static electricity. In such a developing unit, the toner is consumed by its adherence to the photoconductor so that the toner needs to be supplied. This supply is performed by fitting a toner cartridge that stores an appropriate amount of toner to the mount adaptively designed to the developing unit.
Part of toner attracted to the photoconductor surface from the developing unit is untransferred to the paper at the subsequent, transfer unit and remains thereon. Such untransferred toner needs to be removed from the photoconductor surface and collected before the next cycle of exposure and development. For this purpose, use of a toner cartridge for toner supply has been conventionally made in which a toner storage chamber for storing fresh toner and a toner collecting chamber arranged on one side of the toner storage chamber with a partitioning wall in between so that the untransferred toner collected from the photoconductor is kept in the toner collecting chamber and the collected untransferred toner can be disposed of when the toner cartridge is replaced for supplying the toner.
In a toner cartridge of this type, the volume of the toner collecting chamber is determined based on the expected amount of untransferred toner to arise during transfer. However, the actual amount of untransferred toner to be collected varies depending on usage and environmental conditions such as variations in toner charge performance, print paper types and the like. In addition, when, for example, jamming of print paper (paper jam) occurs, the toner adhering on the photoconductor surface at that point is collected in its entirety as the untransferred toner. Thus, there is a risk that the actual amount may markedly increase due to occurrence of inevitable malfunctions.
Under these circumstances, the volume of the toner collecting chamber needs to be designed to be large enough so as to be on the safe side of the expected amount of untransferred toner generated, giving priority to prevention of the collected untransferred toner leaking outside. This therefore results in a large configuration of toner cartridge, giving rise to a problem of constraint on the design flexibility of the image forming apparatus due to reservation of the attachment space of the toner cartridge.
Various proposals have been made in order to solve this problem.
FIG. 1
is a perspective view showing an image forming apparatus configuration disclosed in Japanese Patent Application Laid-Open Hei 4 No.237079. This image forming apparatus includes a toner cartridge comprised of a toner storage chamber (toner container)
101
for storing fresh toner, a toner collecting chamber (waste toner container)
102
for collecting untransferred toner on one side of the toner storage container, a partitioning wall
103
for separating these chambers and a toner passage window
104
formed on the wall and sealed by a shutter which is opened by the force acting from the toner collecting chamber
102
side.
In the drawing,
105
designates a photoconductor drum and
106
designates a cleaning unit for removing untransferred toner left over on the peripheral side of photoconductor drum
105
after transfer. This cleaning unit
106
is connected to toner collecting chamber
102
by way of a collecting pipe
107
incorporating a coil wire as a conveyer means. The untransferred toner removed by cleaning unit
106
is conveyed into toner collecting chamber
102
passing through the collecting pipe
107
and kept in the toner collecting chamber
102
.
According to this configuration, if the collected amount of untransferred toner increases and toner collecting chamber
102
has become full of toner, the shutter that seals the toner passage window
104
as an opening of partitioning wall
103
is released by the pressure of the untransferred toner, applied from the toner collecting chamber side
102
so that part of the untransferred toner in toner collecting chamber
102
returns to toner storage chamber
101
via toner passage window
104
. Accordingly, it is possible to prevent untransferred toner from leaking outside while keeping the volume of toner collecting chamber
102
small, thus alleviating the aforementioned problem.
The untransferred toner returned to toner storage chamber
101
is mixed with the fresh toner and reused. In this case, the untransferred toner is unstable with regard to its charge characteristics and may cause degradation of image quality due to its reuse, but the influence on the image quality is small when the amount of return is trivial.
As already stated above, in this configuration, the shutter that seals toner passage window
104
is adapted to be released by the pressure of the untransferred toner collected in toner collecting chamber
102
. In order to assure this opening action and make the untransferred toner move smoothly, it is necessary to provide optimal design of the shutter opening and closing mechanism and optimal arrangement of the opening position of toner passage window
104
. When an insufficient amount of untransferred toner is returned, there is a possibility of the untransferred toner in toner collecting chamber
102
leaking outside. In contrast, when an excessive amount of untransferred toner is returned, there is the aforesaid problem that degradation of image quality due to the reuse is inevitable.
FIG. 2
is a perspective view showing a configuration of an image forming apparatus disclosed in Japanese Patent Application Laid-Open Hei 8 No.44179. This image forming apparatus includes a toner cartridge comprised of a toner storage chamber (supply toner reservoir)
111
for storing fresh toner, a toner collecting chamber (waste toner reservoir)
112
for collecting untransferred toner on one side of the toner storage chamber, a partitioning wall
113
for partitioning these chambers and a conveyer auger
114
extending across these two chambers, penetrating through the partitioning wall
113
.
When this toner cartridge is attached to the predetermined position of the image forming apparatus, toner collecting chamber
112
is connected t
Funayama Naotaka
Kimura Takahiko
Nagata Tsutomu
Sanada Yoshiaki
Yamaguchi Jun
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