Electrophotography – Control of electrophotography process – Control of developing
Reexamination Certificate
2000-09-15
2003-02-18
Ngo, Hoang (Department: 2852)
Electrophotography
Control of electrophotography process
Control of developing
C399S149000, C399S281000, C399S284000
Reexamination Certificate
active
06522842
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a developing apparatus which forms a developer image by making developer adhere to an electrostatic latent image formed on an image bearing body, and an image forming apparatus such as a copying machine, a printer, or facsimile equipment that performs image formation by an electrographic system and has the above-described developing apparatus.
2. Related Background Art
Various kinds of developing apparatuses are proposed as a developing apparatus used for an image forming apparatus in each electrographic system. For example, recently, an apparatus performing developing in the configuration of pushing a semiconductive roller or a developing roller, having a dielectric layer on its surface, to a surface layer of a photosensitive body, that is, a contact-one-component-type developing apparatus is proposed.
FIG. 16
is a schematic structural diagram showing an image forming apparatus having a conventional contact-one-component-type developing apparatus (hereinafter, this is simply called a developing apparatus) (this image forming apparatus is an electrographic laser beam printer).
A present image forming apparatus has a drum-type electrographic photosensitive body (hereinafter, a photosensitive drum)
1
as an image bearing body. Around the photosensitive drum
1
, a charging roller
2
, a developing apparatus
3
, a transfer roller
4
, and a cleaning blade
5
are arranged, and an exposure device
6
is located outside between the developing device
3
and cleaning blade
5
. Furthermore, in the downstream in a transferring material conveying direction of a transferring nip between the photosensitive drum
1
and transfer roller
4
, a fixing device
7
is located.
In this embodiment, the photosensitive drum
1
is an organic photosensitive body negatively charged and has a photosensitive body layer (not shown) on an aluminum drum base (not shown), is rotatably driven in predetermined peripheral speed in the direction shown by an arrow A (clockwise), and is uniformly charged in a negative polarity by the charging roller
2
contacting in the rotational process.
The charging roller
2
as charging means rotatably contacts to a surface of the photosensitive drum
1
, and uniformly charges the photosensitive drum
1
in predetermined polarity and electric potential by a charging bias applied from a charging bias supply (not shown).
The developing apparatus
3
is a contact-one-component-type developing apparatus performing developing with non-magnetic toner t as one-component developer. The developing apparatus
3
includes a developing roller
11
as a developer bearing body which is located in an opening section of a developing container
10
with facing the photosensitive drum
1
and can be rotate in the direction shown by an arrow (counterclockwise), an elastic roller
12
that can rotate and contacts to the developing roller
11
with pressing the developing roller
11
, a control blade
13
that has elasticity and contacts to the developing roller
11
, and an agitating member
14
agitating the toner t. The control blade
13
contacts to the developing roller
11
for a press-contacting section of the developing roller
11
and elastic roller
12
in the downstream in a rotational direction of the developing roller
11
. The elastic roller
12
rotates in the direction shown by an arrow (clockwise).
The toner t agitated by the agitating member
14
is supplied to a surface of the developing roller
11
by the elastic roller
12
rotating with pressing the developing roller
11
. The toner supplied to the surface of the developing roller
11
is conveyed in connection with the rotation of the developing roller
11
, is charged by friction in a contacting section of the control blade
13
and developing roller
11
, and is laminated on a surface of the developing roller
11
. The toner laminated is conveyed by the rotation of the developing roller
11
, and manifests an electro static latent image with adhering to the electro static latent image formed on the photosensitive drum
1
in the contacting section with the photosensitive drum
1
(developing section). In addition, toner which does not contribute to the developing on the developing roller
11
is scraped off by the elastic roller
12
.
The transferring roller
4
as transferring means forms a transferring nip with contacting to the surface of the photosensitive drum
1
in predetermined pressure, and transfers a toner image on the surface of the photosensitive drum
1
to a transferring material P in the transferring nip between the photosensitive drum
1
and transferring roller
4
with a transferring bias applied from a transferring bias supply (not shown). The transferring roller
4
is rotated in the direction shown by an arrow (counterclockwise).
The cleaning blade
5
removes waste toner that is left on the surface of the photosensitive drum
1
after transferring.
The exposure device
6
includes a laser driver, a laser diode, a polygon mirror, and the like that are not shown. The exposure device
6
forms an electro static latent image corresponding to image information by outputting from the laser diode a laser beam modulated corresponding to a time series electric digital image signal of the image information inputted into the laser driver, scanning the above-described laser beam with the polygon mirror rotating in high speed, and performing image exposure L of the surface of the photosensitive drum
1
through a reflecting mirror (not shown).
The fixing device
7
has a fixing roller
7
a
and a pressure roller
7
b
which can freely rotate, and thermally fixes the toner image transferred on a surface of the transferring material P in the fixing nip between the fixing roller
7
a
and pressure roller
7
b
by heating and pressurizing the toner image with sandwiching and conveying the transferring material P.
Next, image-forming operation by the above-described image forming apparatus will be described.
In image formation, the photosensitive drum
1
is rotationally driven in predetermined peripheral speed in the direction shown by an arrow A by driving means (not shown), and its surface is uniformly charged by the charging roller
2
.
In addition, image exposure L is given by the exposure device
6
on the photosensitive drum
1
that is charged, and an electro static latent image according to image information that is inputted is formed.
Furthermore, as described above, the electro static latent image formed on the photosensitive drum
1
is manifested as a toner image by bonding toner charged in the same polarity as the charged polarity of the photosensitive drum
1
(negative polarity) by the developing roller
11
of the developing apparatus
3
where a developing bias in the same charged polarity as the charged polarity of the photosensitive drum
1
(negative polarity) is applied in a developing section.
Moreover, when the toner image on the photosensitive drum
1
arrives at the transferring nip between the photosensitive drum
1
and transferring roller
4
, the transferring materials P such as paper in a cassette
15
is fed every sheet by a pickup roller
16
in accordance with this timing, and is conveyed in the transferring nip by a resist roller (not shown) and the like.
In addition, the toner image on the photosensitive drum
1
is transferred on the transferring material P, which is conveyed to the transferring nip by the transferring roller
4
where the transferring bias in the polarity reverse (positive polarity) to the polarity of the above-described toner is applied, by an electrostatic force occurring between the photosensitive drum
1
and transferring roller
4
. Furthermore, the transferring material P where the toner image is transferred is conveyed to the fixing device
7
, and is ejected to the outside through a paper output roller
17
after the toner image is thermally fixed by being heated and pressurized on the transferring material P in the fixing nip between the fixing roller
7
a
an
Ishii Yasuyuki
Kakeshita Tomomi
Uehara Shinji
Fitzpatrick ,Cella, Harper & Scinto
Ngo Hoang
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