Information
-
Patent Grant
-
6826378
-
Patent Number
6,826,378
-
Date Filed
Monday, February 24, 200321 years ago
-
Date Issued
Tuesday, November 30, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 399 102
- 399 103
- 399 105
- 399 222
- 399 264
- 399 265
- 399 119
- 399 120
-
International Classifications
-
Abstract
The image forming apparatus is equipped with developer containers for housing developers and a developer carrier that is arranged at the opening of the developer container that is rotatable for supplying developer to an electrostatic latent image on an image carrier. A developing device comprising a narrow portion with an inner wall of the developer container and the developer carrier arranged closely at a point near the opening of the developer container in order to prevent leakage of the developer from the developer container is provided with a developer recovery sheet. One end of the developer recovery sheet is attached to the end of the opening of the developer container and the free end is extending in the direction of the narrow portion in the developer container and is floated up from the developer carrier when the developer carrier is turned.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to developing device and developing method that are used in image forming apparatus such as printers, copying machines, etc.
2. Description of the Related Art
For developing devices of image forming apparatus such as printers, copying machines, etc. to obtain images according to an electro-photographic system, there is so far available an image forming apparatus provided with a narrow portion comprising developer containers and developing rollers arranged closely at a point near the opening of a developing container so as to prevent a developer in a developing container from leaking to the outside during the development or when moving a developing device and this narrow portion is blocked up by a napping of a developer formed on the surface of the developing roller. Particularly, in the case of developing devices available in recent years, that are installed to a revolver and arranged positions of them are changed by rotating them en block to supply different color developers, there is a merit to effectively prevent leakage of developers from developer containers when turning a revolver by providing the above-mentioned narrow portion.
Or, a revolver is provided with a sealing member to block up a clearance between a developing container and a developing roller at the opening of the developer container in order to prevent leakage of developer caused when turning a revolver as disclosed in Japanese Patent Publication No. 2000-75592.
However, the above-mentioned conventional developing devices so far available have not a function to recover toner scattered from carriers in a developer container when toner is separated from carrier and scattered as a result of rotation of developing roller during the developing operation. In a conventional developing device with the above-mentioned narrow portion provided, as the opening of the developer container is not blocked up by a sealing member, scattering toner is once directed to the inside of a developer container from the opening on the air flow caused from the rotation of the developing roller but bounced by the napping portion blocking the narrow portion and scatters again to the outside of the developing container. On the other hand, in a conventional developing device with a sealing member provided at the opening, scattering toner scatters in the periphery without solely taking in a developing container and contaminates periphery equipment or adversely affecting images.
Accordingly, it is desired so far to obtain a developing device that is capable of certainly recovering scattering toner generated when turning a developing roller in a developer container, preventing toner to scatter in the periphery of developing device, obtaining clear images without contaminating peripheral equipment and images by attaching scattering toner to them and reducing frequency of maintenance.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a developing device and a developing method without generating contamination of the periphery by scattering toner by recovering scattering toner generated during the developing operation in developing containers and preventing scattering of toner in the periphery.
According to an embodiment of the present invention, in the image forming devices comprising developer containers for housing developers, rotatable image carriers for supplying developers to electrostatic latent images formed on an image carrier and a narrow portion provided with an inner wall of the developer container and the developer carrier arranged closely at a point near the opening of the developer container, a developer recovery sheet that floats from the developer carrier when turning the carrier is provided, of which one end is attached to the end of the opening of the developer container and the free end is extended in the direction of the narrow portion in the developer container.
Further, according to the embodiment of the present invention, in a developing method using the developing devices provided with the narrow portion comprising the inner wall of the developer container and a rotatable developer carrier closely arranged at a point near the opening of the developer container, the developer recover sheet of which one end is attached to the end of the opening of the developer container and the free end is extended in the direction of the narrow portion in the developer container floats from the developer carrier.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic diagram showing an image forming unit of an image forming apparatus in an embodiment of the present invention;
FIG. 2
is a schematic diagram showing developing devices of an embodiment of this present invention; and
FIG. 3
is a construction diagram showing a urethane sheet of the developing device of an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below in detail referring to attached drawings.
FIG. 1
is a schematic diagram showing an image forming unit
10
of an image forming apparatus of an embodiment of the present invention. Around a photosensitive drum
11
that is an image carrier of the image forming unit
10
, there are arranged a charger
12
for uniformly charging the photosensitive drum
11
in order with the rotation of the photosensitive drum
11
in the arrow direction s, a laser beam applying position
14
to apply a laser beam
13
a
from a laser writing unit
13
from a latent image forming unit for forming a latent image on the charged photosensitive drum
11
, a revolver
19
that is provided with yellow (Y), magenta (M) and cyan (C) developing devices
16
,
17
,
18
and turns in the arrow direction t, an intermediate transferring unit
21
that has an intermediate transferring belt
21
a
that rotates in the arrow u direction, a cleaner
22
and a charge elimination lamp
23
.
The laser writing unit
13
forms an electrostatic latent image on the photosensitive drum
11
by applying laser beams corresponding to writing signals for respective colors according to image data that are input through an external computer terminal or others. As shown in
FIG. 2
, the developing devices
16
,
17
and
18
house developers
26
,
27
and
28
comprising 3 color toners of yellow (Y), magenta (N) and cyan (C) and carrier in developer containers
20
,
21
and
22
, respectively. The revolver
19
turns the yellow (Y), magenta (M) and cyan (C) developing devices
16
to
18
all together by its rotation and arranges desired developing devices
16
to
18
at positions opposing to the photosensitive drum
11
.
The yellow (Y), magenta (M) and cyan (C) developing devices
16
to
18
have magnet rollers
160
a
to
180
a
, developing rollers
160
to
180
comprising developing sleeves
160
b
to
180
b
which turn around the magnet rollers
160
a
to
180
a
, and conveying augers
16
c
to
180
c
which supply yellow (Y), magenta (M) and cyan (C) toners in the developer containers
20
to
22
, respectively. The developing sleeves
160
b
to
180
b
of the developing rollers
160
to
180
turn at a speed of 340 mm/sec. in the arrow direction during the developing operation.
At the mounting ends
20
a
,
21
a
and
22
a
that are the openings of the developer containers
20
,
21
and
22
at the downstream side in the arrow direction v of the developing rollers
160
to
180
, one end of a urethane sheet
24
that is a developer recovering sheet in 0.1 mm thickness and JIS A90 hardness is mounted. The mounting ends
20
a
,
21
a
and
22
a
of the developer containers
20
,
21
and
22
form an angle of 30° with a horizontal line passing through the center of rotation of the developing rollers
160
to
180
.
The urethane sheet
24
is attached to the mounting ends
20
a
,
21
a
and
22
a
up to the point A shown in FIG.
3
and the portion from the point A is in the free state. The point A is at the position 2.8 mm in the vertical direction and 13 mm in the horizontal direction from the center of rotation of the developing rollers
160
to
180
. The free length of the free portion from the point A of the urethane sheet
24
to the free end point B is set at 8.5 mm. Further, the urethane sheet
24
is in contact with the developing rollers
160
to
180
in the somewhat bent state when the developing rollers
160
to
180
are kept stopped. The bent amount of the urethane sheet
24
is so designed that the mounting ends
20
a
,
21
a
and
22
a
thrusts by into the tangent line of the developing rollers
160
to
180
shown by one-dot chain line in
FIG. 3
by about 0.2 mm.
At the end portion of the opening opposing to the mounting ends
20
a
,
21
a
and
22
a
, a doctor blade
30
is provided to control developers
26
to
28
on the developing rollers
160
to
180
. The magnet rollers
160
a
to
180
a
have a developing pole N
1
opposing to the photosensitive drum
11
at the developing position, a conveying pole S
1
to convey the used developers
16
to
28
into the developer containers
20
to
22
, a separation pole N
2
to separate the developers
26
to
28
from the developing rollers
160
to
280
, a grasping pole N
3
to grasp new developers
26
to
28
supplied from the conveying augers
16
c
to
18
c
at the sides of the developing rollers
160
to
180
, and a layer forming pole S
2
opposing to the doctor blade
30
.
Near the mounting ends
20
a
,
21
a
and
22
a
of the developer containers
20
to
22
, a wide clearance is formed between the developing rollers
160
to
180
to make it easy to take in the developers
26
to
28
after used for development. Further, at the upper stream side of the separation pole N
2
of the developer containers
20
to
22
, narrow portions
20
b
to
22
b
having a narrow clearance from the developing rollers
160
to
180
is formed. The narrow portions
20
b
to
22
b
are blocked by the rise of developers
26
to
28
formed on the developing rollers
160
to
180
in order to prevent scattering of the developers
16
to
18
from the developer containers
20
to
22
.
Next, the color image forming process by the image forming unit
10
will be explained. In this image forming unit
10
, a full color image is formed by superposing yellow (Y), magenta (M) and cyan (C) toner images in this order. When starting the image formation, the developing roller
160
of the yellow (Y) developing device
16
mounted to the revolver
19
is arranged opposing to the developing position of the photosensitive drum
11
.
When the image forming process starts, the photosensitive drum
11
turns in the arrow direction s and uniformly charged by the charger
12
with its rotation, applied with laser beam corresponding to an yellow image signal by the laser writing unit
13
at a laser beam apply position
14
. Then, an electrostatic latent image of a yellow image is formed on the photosensitive drum
11
and the drum reaches the revolver
19
. At the revolver
19
, the developing sleeve
160
b
of the developing roller
160
of the yellow developing device 16 turns in the arrow direction v at a velocity of 340 mm/sec.
With this rotation of the developing sleeve
160
b
, the developing roller
160
controls the rise of the developer
26
obtained by the grasping pole N
3
by the doctor blade
30
. And a yellow (Y) toner image is formed on the photosensitive drum
11
by giving a toner to an electrostatic latent image. Thereafter, the developer on the developing roller
160
is conveyed into the developer container
20
by the conveying pole S
1
and separated from the surface of the developer sleeve
160
b
by the separation pole N
2
through the narrow portion
20
b.
During the developing roller
170
in rotating, the free end point B of the urethane sheet
24
is floated from the surface of the developing roller
160
as shown by the dotted line in
FIG. 3
by the wind pressure caused from the rotation of the developing roller
160
. In the clearance between the developing roller
160
and the urethane sheet
24
, the air flow is generated in the arrow direction w, and when toner
26
a
is separated from carrier and scattered when the developing roller
160
is rotating, the scattering toner
26
a
is taken in the developer container by the air flow in the arrow direction w.
The scattering toner
26
a
taken into the developer container
20
is bounced by the developer
26
blocking the narrow portion
20
b
in the direction reverse to the arrow direction w. This bounced scattering toner
26
a
, however, is carried to the urethane sheet side along the inner all of the developer container
20
as shown by the arrow mark x without being scattered to the outside of the developer container
20
. The scattering toner carried to the urethane sheet
24
side is bounced by the urethane sheet
24
in the developer container
20
, carried in the arrow direction y and then, carried again to the narrow portion
20
b
of the developer container together with the scattering toner
26
a
that is newly taken into the developer container on the air flow in the arrow direction w. Meanwhile, the scattering toner
26
a
is conveyed in the direction of the separation pole N
2
jointly with the toner at the narrow portion
20
b
along the rotation of the developing roller
160
.
After completing the developing, the toner image on the photosensitive drum
11
reaches the contacting position with the intermediate transferring belt
21
a
that is rotating in the arrow direction u and is electrostatically transferred primarily on the intermediate transferring belt
21
a
. After completing the primary transfer, the photosensitive drum
11
is cleaned to remove residual toner by the cleaner
22
and the surface charge is eliminated by the charge elimination lamp
23
. Then, the magenta and cyan toner image forming process is repeated on the photosensitive drum
11
in the same manner as the above-mentioned yellow toner image forming process, and yellow (Y), magenta (M) and cyan (C) toner images are transferred intermediately on the intermediate transferring belt
21
a
from the photosensitive drum
11
. Thus, a color toner image with 3 color toner images superposed is formed on the intermediate transferring belt
21
a.
Meanwhile, the revolver
19
turns sequentially in the arrow direction t and arranges the developing rollers
160
to
180
corresponding to a color of a toner image that is formed on the photosensitive drum
11
opposing to the photosensitive drum
11
. When the revolver
19
is turning, the developing rollers
160
to
180
are kept stopped to turn. Yellow (Y), magenta (M) and cyan (C) color toner images superposed on the intermediate transferring belt
21
a
are secondarily transferred in block on a recording paper, etc. and a color image is completed.
While the image forming process is thus repeated, scattering toner generated when the developing rollers
160
to
180
are turning is recovered in the developer container
20
through the clearance between the urethane sheet
24
closing the opening of the developer container and the developing rollers
160
to
180
without scattering in the periphery of the developing devices
16
to
18
.
Further, as a comparison example, the image forming process was executed by changing the urethane sheet
24
in this embodiment with a 0.2 mm thick urethane sheet. As a result, the free end of the urethane sheet was not floated by the wind pressure at the time of rotation but kept in contact with the developing rollers
160
to
180
, and the opening of the developer container
20
was closed by the urethane sheet and the toner is scattered in the periphery without being recovered in the developing container.
According to this embodiment, toners
26
a
to
28
a
scattered from the developing roller
160
to
180
at the time of development are taken into the developer container
20
through the clearance between the urethane sheet
24
and the developing rollers
160
to
180
and further, the scattering of toner again to the outside from the developing container
20
is prevented by the urethane sheet
24
. Accordingly, high grade images are obtained without contaminating peripheral equipment and images by the scattering toners
26
a
to
28
a
and further, frequencies of maintenance for removing scattering toner can be reduced.
Further, the present invention is not restricted to the embodiment described above but can be modified variously within the spirit and scope of the present invention. For example, the developing devices are not limited to those attached to a revolver but a stationary developing device is usable provided that recovery of scattering toner is required using a developer recovery sheet. In addition, the shape of the developer container is not limited but the rotating velocity of the developer carrier is also optional. Material, thickness, shape or mounting angle, etc. of a developer recovery sheet is not limited provided that it is floated by the wind pressure generated when a developer carrier is turning.
Further, when images are developed by installing plural developing devices to the revolver, using toner colors are not limited and the number of developing devices that are installed to the revolver can be four with a black toner developing device added.
According to the present invention as described above, a developer recovery sheet that floats when turning the developer carriers is provided, scattering toner is taken into the developer container by the air flow when turning developer carriers and taken scattering toner is prevented to scatter again from the developer container by the developer recovery sheet. Accordingly, high grade formed images are obtained without contaminating peripheral equipment and images when developing and frequency of maintenance for removing scattered toner adhered to peripheral equipment can be reduced.
Claims
- 1. A developing device comprising:a developer containers to contain developer; a rotatable developer carrier arranged at an opening of the developer container to supply the developer to an electrostatic image on an image carrier; a narrow portion formed by arranging the developer container and the developer carrier closely at a point near the opening of the developer container to prevent leakage of the developer from the developer container; and a developer recovery sheet of which one end is attached to the end of the opening of the developer container and a free end is extending in the narrow portion in the developer container and being floated from the developer carrier when the developer carrier is rotated, wherein the developer recovery sheet is attached to the end of the opening of the developer container at the upper stream than the free end in the revolving direction of the developer carrier and the free end is floated from the developer carrier by the wind pressure generated when the developer carrier is turned.
- 2. The developing device according to claim 1, wherein plural developer containers are attached to a revolver that changes the arranged positions of the plural developer containers by turning the plural developer containers.
- 3. The developing device according to claim 1, wherein the developer recovery sheet is an about 0.1 mm thick urethane sheet.
- 4. The developing device according to claim 1, wherein the developer is magnetic developer, the developer carrier is magnet roller, and the narrow portion is blocked up by the napping of the magnetic developer formed on the magnet roller surface.
- 5. The developing device according to claim 4, wherein the napping of the magnetic developer is formed on the surface of the magnetic roller after passing the narrow portion and is separated from the surface of the magnetic roller at a position above a horizontal line passing a revolving center of the magnetic roller.
- 6. A developing method using a developing device comprising a narrow portion with an inner wall of a developer container and a rotatable developer carrier arranged closely at a position near an opening of the developer container, characterized in that one end of the developer recovery sheet is attached to the end of the opening of the developer container and the free end is extending in the direction of narrow portion in the developer container is floated from the developer carrier when the developer is supplied to an electrostatic latent image on the image carrier by rotating the image carrier, wherein the free end of the developer recovery sheet is floated from the developer carrier by the wind flow generated when the developer carrier is rotated.
- 7. The developing method according to claim 6, wherein plural developer containers are attached to a revolver that changes the arranged positions of the plural developer containers by turning the plural developer containers.
- 8. The developing method according to claim 6, wherein the developer recovery sheet is made of an about 0.1 mm thick urethane sheet.
- 9. The developing method according to claim 6, wherein the developer is a magnetic developer, the developer carrier is a magnetic roller, and the narrow portion is blocked up by a napping of the magnetic developer formed on the surface of the magnetic roller.
- 10. The developing method according to claim 9, wherein the magnetic developer that forms the napping on the surface of the magnetic roller after passing the narrow portion is separated from the surface of the magnetic roller at a position above the horizontal line passing a revolving center of the magnetic roller.
- 11. A developing device for use with an image forming apparatus having an image carrier, the developing device comprising:at least one developer container that contains developer, the developer container having an opening; a rotatable developer carrier positioned arranged adjacent the opening of the developer container, for supplying the developer to an electrostatic image on an image carrier; a narrow portion in the developer container, formed between the developer container and the developer carrier adjacent the opening of the developer container; and a developer recovery sheet having a first end attached to the developer container, and a second end freely extending in the narrow portion in the developer container, wherein the free end of the developer recovery sheet is floated from the developer carrier by wind pressure generated when the developer carrier is rotated.
- 12. The developing device according to claim 11, comprising a plurality of developer containers attached to a revolver, wherein the revolver rotates to change the arranged positions of the plural developer containers relative to the image carrier.
- 13. The developing device according to claim 11, wherein the developer recovery sheet is an about 0.1 mm thick urethane sheet.
- 14. The developing device according to claim 11, wherein the developer is magnetic developer, the developer carrier is a magnet roller, and the narrow portion is blocked by the napping of the magnetic developer formed on the magnet roller surface.
- 15. The developing device according to claim 14, wherein the napping of the magnetic developer is formed on the surface of the magnetic roller after passing the narrow portion and is separated from the surface of the magnetic roller at a position above a horizontal line passing a revolving center of the magnetic roller.
- 16. The developing device according to claim 11, wherein, in a stopped position of the developer carrier, the developer recovery sheet is bent radially outward by the developer carrier.
- 17. The developing device according to claim 16, wherein the developer recovery sheet is bent radially outward by about 0.2 mm.
US Referenced Citations (1)
| Number |
Name |
Date |
Kind |
|
6181897 |
Kawai |
Jan 2001 |
B1 |
Foreign Referenced Citations (1)
| Number |
Date |
Country |
| 2000-075592 |
Mar 2000 |
JP |
