Electrophotography – Diagnostics – Consumable
Reexamination Certificate
1999-10-20
2001-05-01
Pendegrass, Joan (Department: 2852)
Electrophotography
Diagnostics
Consumable
C399S254000
Reexamination Certificate
active
06226464
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a developing apparatus which is applicable to an image forming apparatus such as an electrophotographic apparatus.
2. Related Background Art
FIG. 9
shows an example of a conventional image forming apparatus having a developing apparatus.
FIG. 9
is a vertical cross-sectional view showing the schematic structure of the image forming apparatus, and referring to the figure, the outline of the conventional image forming apparatus will be described.
A photosensitive drum (image bearing member)
111
is rotationally driven in a direction indicated by an arrow RI so that after a surface of the photosensitive drum
111
is uniformly charged by a charging roller (charging device)
103
, it is subject to exposure by an exposing device
102
to thereby form an electrostatic latent image on the surface of the photosensitive drum
111
. The electrostatic latent image is developed as a toner image by a developing apparatus
208
. The toner image on the photosensitive drum
111
is transferred to a transfer material
114
by a transfer roller (transfer device)
110
. The transfer material
114
which has been received in a sheet feed cassette
117
is supplied by a sheet feed roller
116
and so on. Toner which is not transferred and remains on the surface of the photosensitive drum
111
from which the toner image has been transferred is removed by a cleaning blade
113
of a cleaning device
112
for succeeding image formation. On the other hand, the toner image which has been transferred to the transfer material
114
is fixed onto the surface of the transfer material
114
by a fixing device
115
and thereafter discharged to the exterior of an image forming apparatus main body
101
. With the above operation, image formation is completed.
FIG. 10
shows an example of a conventional developing apparatus.
FIG. 10
is an enlarged diagram of the developing apparatus
208
shown in FIG.
9
. Referring to the figure, the outline of the conventional developing apparatus will be described.
The developing apparatus
208
shown in the figure is comprised of a developing apparatus using one-magnetic-component toner. A developing sleeve (developer bearing member)
105
is comprised of a non-magnetic sleeve which is formed of a pipe made of aluminum or stainless steel and rotatably supported in a direction indicated by an arrow R
2
. Inside of the developing sleeve
105
is fixedly disposed a magnet
106
having a plurality of N-poles and S-poles which are alternately formed. A surface of the developing sleeve
105
is so processed as to provide an appropriate surface roughness so that a desired amount of toner can be carried. The surface of the developing sleeve
105
abuts against one end of an elastic blade (developer regulation member)
107
a
under a given pressure. The elastic blade
107
a
is made of, for example, urethane rubber, silicon rubber or the like and the end of the elastic blade
107
a
is fixed to a support plate
107
b
. Toner
109
which has been attracted to the surface of the developing sleeve
105
due to a magnetic force of the magnet
106
is supplied with an appropriate amount of charges by a frictional charge caused by bearing and carrying the toner
109
on the developing sleeve
105
and a frictional charge caused by sliding friction between the developing sleeve
105
and the elastic blade
107
a
at the time where the toner
109
is regulated to an appropriate amount by the elastic blade
107
a
. The toner
109
is then carried to a developing region.
Also, the developing apparatus
208
is designed in such a manner that, as shown in
FIG. 15
, rollers
209
are disposed at both end portions of the developing sleeve
105
, and the rollers
209
are allowed to abut against the photosensitive drum
111
so that a given interval is provided between the surface of the developing sleeve
105
and the surface of the photosensitive drum
111
. A developing sleeve gear
212
is fixed onto one end of the developing sleeve
105
so that the developing sleeve
105
is rotationally driven by a drive force which is transmitted to the developing sleeve gear
212
from a photosensitive drum gear
211
integral with the photosensitive drum
111
.
As means for detecting the remaining amount of toner in the developing apparatus
208
thus structured, there has been known, up to now, a technique in which a variation in current which is induced by an a.c. developing bias supply power source
118
is detected by an antenna member
108
disposed in parallel with the developing sleeve
105
, using a variation in impedance which is accompanied by a variation in the amount of toner between the developing sleeve and the antenna as shown in
FIG. 10
, to thereby estimate the remaining amount of toner (hereinafter referred to as “induced current detecting means). The power source for supplying the developing bias includes not only the above-described a.c. developing bias supply power source
118
but also a d.c. developing bias supply power source
119
, by which a developing bias where a.c. voltage and d.c. voltage are superposed on each other is supplied to the above-described developing sleeve
105
.
The induced current detecting means is made up of the respective members
120
to
123
in FIG.
10
. Reference numeral
120
denotes a capacitor having an electrostatic capacitance equal to that in a state where no toner exists. The electrostatic capacitance of the capacitor
120
and an electrostatic capacitance detected by the antenna member
108
are compared with each other after they pass through diodes
121
and
122
, respectively, to thereby judge whether the toner exists or not.
In the case of detecting the remaining amount of toner, the antenna member
108
disposed inside of a developing container
104
in the longitudinal direction may prevent the movement of toner. In particular, because a toner wall is liable to be formed between the lower portion of the developing container
104
and the antenna member
108
, a method has been conventionally applied in which an agitating member
130
is disposed at the lower portion of the antenna member
108
so that the supply of toner to the developing sleeve
105
is smoothed while toner is being unraveled.
As the agitating member
130
, there is used a crank-shaped bar member as shown in
FIG. 11
, which is rotated in a direction indicated by an arrow R
3
with both end portions thereof as a rotating center. This is a conventional method.
Also, an agitating member
7
is so disposed as to unravel the toner within the developing container
104
and deliver the toner to the agitating member
130
. The agitating member
7
is formed of a crank-shaped bar member as in the agitating member
130
as shown in
FIG. 12
, which is rotated in a direction indicated by an arrow R
4
in
FIG. 10
with both end portions thereof as a rotating center. In general, a driving force that permits the agitating member
130
and the agitating member
7
to rotate is obtained, for example, by lowering the driving force transmitted from the above-described developing sleeve gear
212
(refer to
FIG. 15
) to an appropriate rotating speed through a gear train.
However, for example, in the image forming apparatus of the digital system which performs exposure by a laser beam, with the decreased diameter of the toner for the purpose of improving the reproducibility of one dot, a tendency is given to lower the density of an image for some time after the developing apparatus
208
structured in the above manner starts to operate.
FIG. 13
is a graph representative of an initial image density transition with respect to a difference in toner average (center) particle diameters. Although the initial density is low in both of cases where the average particle diameters are 6 and 8 &mgr;m, the case where the average particle diameter is smaller, that is, 6 &mgr;m is more remarkable for the initial lower density. The level of the initial low density in the case where the average particle di
Matsumoto Hideki
Okano Keiji
Sunahara Satoshi
Suwa Koichi
Yoshida Masahiro
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Pendegrass Joan
LandOfFree
Developer apparatus featuring a developer container... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Developer apparatus featuring a developer container..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Developer apparatus featuring a developer container... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2448058