U.S. patent number RE38,978 [Application Number 09/956,214] was granted by the patent office on 2006-02-14 for toner transporting method and mechanism employing a belt conveyor.
This patent grant is currently assigned to Oki Data Corporation. Invention is credited to Atsushi Kobayashi, Shigeki Nakajima.
United States Patent |
RE38,978 |
Nakajima , et al. |
February 14, 2006 |
Toner transporting method and mechanism employing a belt
conveyor
Abstract
An electrophotographic printer has a toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism with a belt conveyor that
transports toner from a toner collection chamber, in which toner
removed from the photosensitive drum of the printer is collected,
to a toner delivery chamber.[., from which toner is returned to the
developing unit of the printer.]. . The belt conveyor is disposed
in a channel that loops around the ends of roller shafts in the
printer, and does not increase the width of the printer. The toner
.[.recycling.]. .Iadd.transporting .Iaddend.mechanism is easily
assembled, and can be driven without motion irregularities.
Inventors: |
Nakajima; Shigeki (Tokyo,
JP), Kobayashi; Atsushi (Tokyo, JP) |
Assignee: |
Oki Data Corporation (Tokyo,
JP)
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Family
ID: |
26365544 |
Appl.
No.: |
09/956,214 |
Filed: |
September 19, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
09094938 |
Jun 15, 1998 |
05956556 |
Sep 21, 1999 |
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Foreign Application Priority Data
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Jun 19, 1997 [JP] |
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9-162759 |
Feb 9, 1998 [JP] |
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10-027601 |
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Current U.S.
Class: |
399/359;
399/358 |
Current CPC
Class: |
G03G
21/105 (20130101) |
Current International
Class: |
G03G
21/10 (20060101) |
Field of
Search: |
;399/343,352,358,359 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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5-181397 |
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Jul 1993 |
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JP |
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9-062166 |
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Mar 1997 |
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JP |
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9-106235 |
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Apr 1997 |
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JP |
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9-120207 |
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May 1997 |
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JP |
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Primary Examiner: Lee; Susan
Attorney, Agent or Firm: Akin Gump Strauss Hauer & Feld,
LLP
Claims
What is claimed is:
1. A method of .[.recycling.]. .Iadd.transporting .Iaddend.toner in
an electrophotographic printer having a photosensitive drum on
which a latent image is formed, a developing unit for developing
the latent image by application of toner, and a transfer unit for
transferring the developed image from the photosensitive drum to a
printing medium, comprising the steps of: removing toner from said
photosensitive drum after transfer of said image to said printing
medium; collecting the toner thus removed in a toner collection
chamber; using a belt conveyor to transport the toner from said
toner collection chamber to a toner delivery chamber; .[.returning
the toner from said toner delivery chamber to said developing
unit;.]. using an idle rotatable element turning on a shaft to move
said belt conveyor, said rotatable element rotating in relation to
said shaft; and allowing foreign matter that becomes caught between
said idle rotatable element and said shaft to escape through a
groove formed in one of an outer surface of said shaft and an inner
surface of said idle rotatable element.
2. A method of .[.recycling.]. .Iadd.transporting .Iaddend.toner in
an electrophotographic printer having a photosensitive drum on
which a latent image is formed, a developing unit for developing
the latent image by application of toner, and a transfer unit for
transferring the developed image from the photosensitive drum to a
printing medium, comprising the steps of: removing toner from said
photosensitive drum after transfer of said image to said printing
medium; collecting the toner thus removed in a toner collection
chamber; using a belt conveyor to transport the toner from said
toner collection chamber to a toner delivery chamber; .[.returning
the toner from said toner delivery chamber to said developing
unit;.]. driving said belt conveyor by rotating a toothed wheel
engaging said belt conveyor; and allowing toner that is picked up
by said toothed wheel from said belt conveyor to drop through a
passage and return to said belt conveyor.
3. A method of .[.recycling.]. .Iadd.transporting .Iaddend.toner in
an electrophotographic printer having a photosensitive drum on
which a latent image is formed, a developing unit for developing
the latent image by application of toner, and a transfer unit for
transferring the developed image from the photosensitive drum to a
printing medium, comprising the steps of: removing toner from said
photosensitive drum after transfer to said image to said printing
medium; collecting the toner thus removed in a toner collection
chamber; using a belt conveyor to transport the toner from said
toner collection chamber to a toner delivery chamber; .[.returning
the toner from said toner delivery chamber to said developing
unit;.]. and driving a screw conveyor having a toothed end, said
screw conveyor conveying said toner from one end of said toner
delivery chamber toward a more central part of said toner delivery
chamber, the toothed end of said screw conveyor simultaneously
driving said belt conveyor.
4. A toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
for an electrophotographic printer having a photosensitive drum on
which a latent image is formed, a developing unit for developing
said latent image by application of toner, and a transfer unit for
transferring the developed image to a printing medium, comprising:
a toner .[.recycling.]. .Iadd.transporting .Iaddend.portion, having
a channel forming a loop, with a pick-up station at a first
position in said loop and a discharging station at a second
position in said loop; a cleaning unit attached to said toner
.[.recycling.]. .Iadd.transporting .Iaddend.portion, for removing
said toner from said photosensitive drum after transfer of said
image to said printing medium.Iadd., said cleaning unit
.Iaddend.having a toner collection chamber opening into said
channel at said pick-up station for holding the toner thus removed,
and a first conveyor for conveying the toner in said toner
collection chamber to said pick-up station; a toner delivery
chamber attached to said toner .[.recycling.]. .Iadd.transporting
.Iaddend.portion, opening into said chamber at said discharging
station; and a .Iadd.second conveyor in the form of a .Iaddend.belt
conveyor disposed in .Iadd.and guided by .Iaddend.said channel, for
conveying said toner from said pick-up station to said discharging
station.
5. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 4, wherein said photosensitive drum, said developing unit,
and said toner .[.recycling.]. .Iadd.transporting .Iaddend.portion
form part of a changeable cartridge in said electrophotographic
printer.
6. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 4, further comprising a pulley disposed inside said loop,
in contact with said belt conveyor for driving said belt
conveyor.
7. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 4, further comprising a toothed wheel disposed outside
said loop, in contact with said belt conveyor, for driving said
belt conveyor.
8. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 7, wherein said toner .[.recycling.]. .Iadd.transporting
.Iaddend.portion has a passage disposed below said toothed wheel
and communicating with said channel, for receiving toner that is
picked up by said toothed wheel from said belt conveyor and then
dropped, and returning said toner to said belt conveyor.
9. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 4, .[.wherein said second conveyor is.]. .Iadd.further
comprising a third conveyor which is in the form of .Iaddend.a
screw conveyor with teeth at one end, said teeth engaging and
driving said .[.belt.]. .Iadd.second .Iaddend.conveyor.
10. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 4, wherein said belt conveyor has an outer surface with
lateral ribs for carrying said toner.
11. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 4, wherein said belt conveyor has an outer surface with
depressed pockets for carrying said toner.
12. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 4, wherein said belt conveyor has cut-out holes for
carrying said toner.
13. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 4, wherein said belt conveyor has an outer surface with
teeth for carrying said toner.
14. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 13, wherein said teeth are set at an angle toward a
direction of travel of said belt conveyor.
15. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 4, wherein said belt conveyor has a longitudinal rib, and
said channel has a groove accommodating said longitudinal rib,
thereby preventing said belt conveyor from being installed in an
incorrect orientation in said channel.
16. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 4, further comprising: a shaft attached to said toner
.[.recycling.]. .Iadd.transporting .Iaddend.portion, having a
grooved cylindrical surface; and an idle rotatable element mounted
on said shaft, for moving said belt conveyor, said rotatable
element rotating in relation to said shaft; the grooved cylindrical
surface of said shaft providing an escape route for foreign matter
that becomes caught between said shaft and said idle rotatable
element.
17. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 16, wherein the grooved cylindrical surface of said shaft
has at least one longitudinal wedge-shaped groove.
18. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 16, wherein the grooved cylindrical surface of said shaft
has a helical groove.
19. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 16, wherein said idle rotatable element is an idle gear
transmitting torque to said belt conveyor.
20. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 4, further comprising: a shaft attached to said toner
.[.recycling.]. .Iadd.transporting .Iaddend.portion; and an idle
rotatable element mounted on said shaft, for moving said belt
conveyor, said rotatable element rotating in relation to said
shaft, said idle rotatable element having a grooved inner surface
in contact with said shaft, the grooved inner surface of said idle
rotatable element providing an escape route for foreign matter that
becomes caught between said shaft and said idle rotatable
element.
21. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 20, wherein the grooved inner surface of said idle
rotatable element has a helical groove.
22. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 21, wherein said idle rotatable element is an idle gear
transmitting torque to said belt conveyor.
23. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 20, wherein said idle rotatable element is an idle gear
transmitting torque to said belt conveyor.
24. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 4, further comprising an interfering member making contact
with said belt conveyor at said discharging station, thereby
loosening said toner from said belt conveyor.
25. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 24, wherein said interfering member comprises a projection
in an outer wall of said channel.
26. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 24, wherein said interfering member comprises a flexible
blade attached to said toner .[.recycling.]. .Iadd.transporting
.Iaddend.portion and extending into said channel.
27. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 4, wherein: said developing unit has a roller turning on a
shaft; and said toner .[.recycling.]. .Iadd.transporting
.Iaddend.portion forms a side frame supporting one end of said
shaft.
28. The toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
of claim 27, wherein said channel forms a loop around said one end
of said shaft.
.Iadd.29. The toner transporting mechanism of claim 4, wherein said
toner transporting portion forms a side frame supporting one end of
a shaft of said photosensitive drum. .Iaddend.
.Iadd.30. The toner transporting mechanism of claim 29, wherein
said channel forms a loop around said one end of said shaft.
.Iaddend.
.Iadd.31. A method of transporting toner in an electrophotographic
printer having a photosensitive drum on which a latent image is
formed, a developing unit for developing the latent image by
application of toner, and a transfer unit for transferring the
developed image from the photosensitive drum to a printing medium,
comprising the steps of: removing toner from said photosensitive
drum after transfer of said image to said printing medium;
collecting the toner thus removed in a toner collection chamber;
and slidably guiding a belt conveyor along a channel connecting the
tone collection chamber to a toner delivery chamber to transport
toner from the toner collection chamber to the toner delivery
chamber. .Iaddend.
.Iadd.32. A toner transporting mechanism for an electrophotographic
printer having a photosensitive drum on which a latent image is
formed, a developing unit for developing said latent image by
application of toner, and a transfer unit for transferring the
developed image to a printing medium, comprising: a toner
transporting portion, having a channel with a pick-up station at a
first position along said channel and a discharge station at a
second position along said channel; a cleaning unit attached to
said toner transporting portion for removing said toner from said
photosensitive drum after transfer of said image to said printing
medium, a toner collection chamber opening into said channel at
said pick-up station for holding the toner thus removed, and a
first conveyor for conveying the toner in said toner collection
chamber to said pick-up station; a toner delivery chamber attached
to said toner transporting portion, opening into said channel at
said discharging station; and a second conveyor in the form of a
belt conveyor disposed in and slidably guided by said channel, for
conveying said toner from said pick-up station to said discharging
station. .Iaddend.
.Iadd.33. The toner transporting mechanism of claim 32, wherein
said photosensitive drum, said developing unit, and said toner
transporting portion form part of a changeable cartridge in said
electrophotographic printer. .Iaddend.
.Iadd.34. The toner transporting mechanism of claim 32, further
comprising a third conveyor which is in the form of a screw
conveyor with teeth at one end, said teeth engaging and driving
said second conveyor. .Iaddend.
.Iadd.35. The toner transporting mechanism of claim 32, wherein
said developing unit has a roller turning on a shaft; and said
toner transporting portion forms a side frame supporting one end of
said shaft. .Iaddend.
.Iadd.36. The toner transporting mechanism of claim 32, wherein
said toner transporting portion forms a side frame supporting one
end of a shaft of said photosensitive drum. .Iaddend.
.Iadd.37. The toner transporting mechanism of claim 32, wherein
said second conveyor has a surface with lateral ribs for carrying
said toner. .Iaddend.
.Iadd.38. The toner transporting mechanism of claim 32, wherein
said second conveyor has a surface with depressed pockets for
carrying said toner. .Iaddend.
.Iadd.39. The toner transporting mechanism of claim 32, wherein
said second conveyor has cut-out holes for carrying said toner.
.Iaddend.
.Iadd.40. The toner transporting mechanism of claim 32, wherein
said second conveyor has a surface with teeth for carrying said
toner. .Iaddend.
.Iadd.41. The toner transporting mechanism of claim 40, wherein
said teeth are set at an angle toward a direction of travel of said
second conveyor. .Iaddend.
.Iadd.42. The toner transporting mechanism of claim 32, wherein
said channel is formed in a side frame. .Iaddend.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a method and a mechanism for
.[.recycling.]. .Iadd.transporting .Iaddend.toner in an
electrophotographic printer.
An electrophotographic printer forms a lateral electrostatic image
on a photosensitive drum, develops the image by application of
toner, then transfers the toner from the drum to a printing medium
such as a sheet of paper. In many electrophotographic printers, the
photosensitive drum and developing unit are part of a replaceable
cartridge that also includes a cleaning unit for cleaning the
photosensitive drum by removing toner that fails to be transferred
to the printing medium.
Many electrophotographic printers have a recycling mechanism that
returns toner form the cleaning unit to the developing unit, so
that toner recovered by the cleaning unit can be reused. Such
recycling of toner has several advantages: more pages can be
printed before the toner supply has to be replenished; no tank is
needed to store toner removed by the cleaning unit; and the toner
removed by the cleaning unit does not have to be disposed of.
The toner recycling mechanism is part of the replaceable cartridge.
A conventional toner recycling mechanism comprises three helical
screw conveyors. The first screw conveyor conveys toner to one end
of the cleaning unit. The second screw conveyor conveys toner from
this end of the cleaning unit to the corresponding end of the
developing unit. The third screw conveyor conveys toner into the
developing unit.
The replaceable cartridge also includes various rollers, such as a
developing roller for applying toner to the photosensitive drum and
a supply roller for supplying toner to the developing roller. The
first and third screw conveyors of the toner recycling mechanism
are oriented parallel to these rollers, but the second screw
conveyor is oriented at a right angle to the rollers. To avoid
interference with the rollers, the second screw conveyor must be
disposed at one side of the cartridge, beyond the ends of the
roller shafts. The cartridge must accordingly be widened to
accommodate the second screw conveyor, but this undesirably
increase the dimensions of the printer.
Another disadvantage of the conventional toner recycling mechanism
is that the second screw conveyor must be driven by a gear train
including a worm gear. This type of gear train produces a thrust
force that places an extra load on the driving motor, leading to
uneven motion and irregular printing. The existence of the worm
gear train also makes the replaceable cartridge more difficult to
assemble.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide a
toner .[.recycling.]. .Iadd.transporting .Iaddend.method and
mechanism that do not increase the dimensions of an
electrophotographic printer.
Another object of the invention is to provide a toner
.[.recycling.]. .Iadd.transporting .Iaddend.method and mechanism
that do not cause printing irregularities.
Another object is to provide a toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism that is easy to assemble.
The invented toner .[.recycling.]. .Iadd.transporting
.Iaddend.method uses a belt conveyor to transport toner from a
toner collection chamber, in which toner removed from the
photosensitive drum of an electrophotographic printer is collected,
to a toner delivery chamber.[., from which the toner is returned to
the developing unit of the printer.]. .
The invented toner .[.recycling.]. .Iadd.transporting
.Iaddend.mechanism comprises a side frame supporting one end of the
shaft of a roller in the developing unit of the printer. The side
frame has a channel forming a loop around the end of the shaft. A
pick-up station is disposed at one end of the loop, and a
discharging station at another end of the loop.
A cleaning unit removes toner from the photosensitive drum. The
toner removed by the cleaning unit is held in a toner collection
chamber that opens into the channel at the pick-up station. A
conveyor in the toner collection chamber carries the toner to the
pick-up station.
A belt conveyor disposed in the channel carries the toner from the
pick-up station to the discharging station. At the discharging
station, the toner is discharged into a toner delivery chamber.[.,
from which another conveyor returns the toner to the developing
unit.]. .
The belt conveyor preferably has ribs, pockets, cut-out holes, or
teeth for carrying the toner. The belt conveyor may also have a
longitudinal rib that fits into a groove in the channel, to prevent
the belt conveyor from being installed in the wrong orientation.
The belt conveyor maybe driven by a pulley disposed inside the loop
of the channel, by a toothed wheel disposed outside the loop, or by
a toothed end of the conveyor in the toner delivery chamber. Torque
may be transmitted to the belt conveyor by an idle gear turning on
a stationary shaft, in which case a groove is preferably provided
on the outer surface of the stationary shaft, or the inner surface
of the idle gear, to permit the escape of toner or other foreign
matter that becomes caught between the idle gear and stationary
shaft. Vibration may be imparted to the belt conveyor by an
interfering member to promote the release of toner at the
discharging station.
The channel that houses the belt conveyor is disposed inboard of
the end of the shaft of the roller in the developing unit, so the
invented toner .[.recycling.]. .Iadd.transporting
.Iaddend.mechanism does not increase the dimensions of the
printer.
No worm gear is required to drive the belt conveyor, so printing
irregularities due to the thrust produced by a worm gear are
avoided.
The invented toner .[.recycling.]. .Iadd.transporting
.Iaddend.mechanism is easy to assemble because it has relatively
few parts.
BRIEF DESCRIPTION OF THE DRAWINGS
In the attached drawings:
FIG. 1 shows a sectional view of an electrophotographic
printer;
FIG. 2 shows a side view of a conventional toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism;
FIG. 3 shows a plan view of the conventional toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism;
FIG. 4 shows a side view of a toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism according to a first
embodiment of the invention;
FIG. 5 shows a perspective view of the toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism in FIG. 4;
FIG. 6 is a partly cutaway perspective view showing the conveyor in
the toner collection chamber in FIG. 4;
FIG. 7 is a perspective view showing one possible configuration of
the belt conveyor in the first embodiment;
FIG. 8 is a perspective view showing another possible configuration
of the belt conveyor in the first embodiment;
FIG. 9 is a perspective view showing another possible configuration
of the belt conveyor in the first embodiment;
FIG. 10A, FIG. 10B, and FIG. 10C are side views of the first
embodiment, illustrating the transport of toner by the belt
conveyor;
FIG. 11 shows a side view of a toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism according to a second
embodiment of the invention;
FIG. 12 is a perspective view illustrating the gear train by which
the toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism is
driven in the second embodiment;
FIG. 13 is a perspective view of the belt conveyor in the second
embodiment;
FIG. 14 is a side view illustrating the efficient vertical
transport of toner by the belt conveyor in the second
embodiment;
FIG. 15 is a side view illustrating less efficient vertical
transport of toner by a belt conveyor with symmetrical teeth;
FIG. 16 is a schematic view comparing the scooping action of the
belt conveyor in the second embodiment with the scooping action of
a belt conveyor having symmetrical teeth;
FIG. 17 shows a side view of a toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism according to a third
embodiment of the invention;
FIG. 18 shows a perspective view of the belt conveyor in the third
embodiment;
FIG. 19 is a sectional view through line X--X in FIG. 17,
illustrating correct installation of the belt conveyor in the third
embodiment;
FIG. 20 is a similar sectional view illustrating incorrect
installation of the belt conveyor in the third embodiment;
FIG. 21 is a perspective view showing the side frame in a toner
.[.recycling.]. .Iadd.transporting .Iaddend.mechanism according to
a fourth embodiment of the invention;
FIG. 22 is an exploded perspective view of the idle gear and its
stationary shaft in the fourth embodiment;
FIG. 23 is a perspective view of the stationary shaft of the idle
gear in a toner .[.recycling.]. .Iadd.transporting
.Iaddend.mechanism according to a fifth embodiment of the
invention;
FIG. 24 is a perspective view of the idle gear in a toner
.[.recycling.]. .Iadd.transporting .Iaddend.mechanism according to
a sixth embodiment of the invention;
FIG. 25 is a side view showing a toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism according to a seventh
embodiment of the invention;
FIG. 26 is a side view showing a toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism according to an eighth
embodiment of the invention;
FIG. 27 is a perspective view of the toothed screw conveyor in the
eighth embodiment;
FIG. 28 is a side view showing a toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism according to a ninth
embodiment of the invention; and
FIG. 29 is a side view showing a toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism according to a tenth
embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the invention will be described to reference to the
attached illustrative drawings. As an illustration of the type of
printer in which the invention can be employed, and of the type of
toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism that
the invention replaces, a brief description of an
electrophotographic printer with a conventional toner
.[.recycling.]. .Iadd.transporting .Iaddend.mechanism will be given
first.
FIG. 1 shows the main parts of this printer. A paper cassette 2
holds sheets of paper 4, which are fed by hopping roller 6 and a
pair of transport rollers 8 on a paper path because a replaceable
cartridge, referred to below as the printing process cartridge 10,
and a transfer unit 12. An optical printing head 14 creates an
image that is developed in the printing process cartridge 10 and
transferred by the transfer unit 12 to a sheet of paper 4. The
transferred image is fused onto the paper by a fusing unit 16. A
pair of delivery rollers 18 feeds the resulting printed pages to a
face-down delivery tray 20 or a face-up delivery tray 22.
The printing process cartridge 10 comprises a photosensitive drum
24, a charging unit 26 that charges the photosensitive drum 24 to a
uniform potential preparatory to image formation, a developing unit
28 that develops the image by applying toner, a toner cartridge 30
from which the toner is supplied, and a cleaning unit 32 that
removes remaining toner from the photosensitive drum 24 after
transfer of the image to the paper 4. The developing unit 28
comprises a developing roller 34 that applies toner to the surface
of the photosensitive drum 24, and a supply roller 36 that supplies
toner to the developing roller 34.
FIG. 2 is an enlarged view of the printing process cartridge 10 as
seen from the opposite side, showing the cleaning blade 38 of the
cleaning unit 32, and the three screw conveyors 40, 42, and 44 of
the conventional toner .[.recycling.]. .Iadd.transporting
.Iaddend.mechanism. The first screw conveyor 40 brings toner from
the cleaning unit 32 to the base of the second screw conveyor 42,
which carries the toner upward through an inclined passage 46 to
the third screw conveyor 44, as indicated by the arrow. The second
screw conveyor is driven by a gear train comprising gears 48, 50,
and 52.
FIG. 3 shows how the three screw conveyors 40, 42, and 44 are
disposed in relation to the photosensitive drum 24, developing
roller 34, and supply roller 36, illustrating the fact that the
printing process cartridge 10 must be widened to accommodate the
second screw conveyor 42. FIG. 3 also shows two additional gears 54
and 56 by which the first screw conveyor 40 is driven. The rotation
of the photosensitive drum 24 is transmitted by gears 54 and 56 to
the first screw conveyor 40, then by gear 48, 50, and 52 to the
second screw conveyor 42. Gear 50 is a worm gear.
The rotation of the photosensitive drum 24 is also transmitted by
gears (not shown) to the rollers 34 and 36 and the third screw
conveyor 44. The photosensitive drum 24 is driven by a motor (not
visible).
FIG. 4 shows a side view of a printing process cartridge 58 having
a toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism
according to a first embodiment of the invention. The
photosensitive drum 24 and the developing unit 28 with its
developing roller 34 and supply roller 36 are similar to the
corresponding elements in FIG. 1. Whereas FIG. 1 showed a charging
unit 26, FIG. 4 shows a charging roller 60, which makes contact
with the surface of the photosensitive drum 24 to apply a uniform
electrostatic charge. The printing process cartridge 58 also has a
toner cartridge (not visible) similar to the one in FIG. 1.
The cleaning unit 62 in FIG. 4 has a cleaning blade 64 that scrapes
toner from the surface of the photosensitive drum 24, allowing the
toner to fall into a toner collection chamber 66. A screw conveyor
68 brings the collected toner to one end of the toner collection
chamber 66.
The side frame or toner .[.recycling.]. .Iadd.transporting
.Iaddend.portion 70 on the illustrated side of the printing process
cartridge 58 has a channel 72 that loops around the ends of the
shafts of the photosensitive drum 24 and the rollers 34 and 36 in
the developing unit 28. The channel 72 is occupied by a belt
conveyor 74. A pulley 76 at one end of the channel 72, disposed
inside the loop of the channel 72, turns in the decision of arrow
A, moving the belt conveyor 74 in the direction of arrow B. At the
other end, the channel 72 opens into the toner collection chamber
66 of the cleaning unit 62. The pick-up station 78 of the belt
conveyor 74 is disposed in the region where the channel 72 meets
the toner collection chamber 66 i.e., a first portion; the
discharge station 80 of the belt conveyor 74 is disposed beneath
the pulley 76 i.e., second portion. The belt conveyor 74 discharges
into a toner delivery chamber 82, from which a screw conveyor 84
carries toner to the developing unit 28.
FIG. 5 is a perspective view of the side frame or toner
.[.recycling.]. .Iadd.transporting .Iaddend.portion 70, showing
that the ends of the shafts of the photosensitive drum 24,
developing roller 34, supply roller 36, and charging roller 60
extend outboard from the surface of the side frame or toner
.[.recycling.]. .Iadd.transporting .Iaddend.portion 70, while the
channel 72 extends inboard from this surface. The channel 72 and
belt conveyor 74 accordingly do not increase the width of the
printing process cartridge 58. Nor is the width increased by the
screw conveyors 68 and 84 and pulley 74, since the ends of their
shafts extend less far outboard than do the ends of the shafts of
the photosensitive drum 24, developing roller 34, supply roller 36,
and charging roller 60.
FIG. 6 is a partially cutaway perspective view showing the screw
conveyor 68 in the toner collection chamber 66. The side frame or
toner .[.recycling.]. .Iadd.transporting .Iaddend.portion 70 has a
side cover that prevents toner from escaping from the channel 72.
This cover is also partially cut away in FIG. 6, to show the
pick-up station 78 where toner brought by the screw conveyor 68 is
transferred to the belt conveyor 74. To facilitate transport of the
toner, the belt conveyor 74 may have raised lateral ribs 86 as
shown in FIG. 7, or depressed pockets 88 as shown in FIG. 8.
Alternatively, the belt conveyor 74 maybe a mesh belt with cut-out
holes 89 as shown in FIG. 9.
The invented toner .[.recycling.]. .Iadd.transporting
.Iaddend.mechanism operates as follows. The motor (not shown) that
drives the photosensitive drum 24 also drives the pulley 76 and the
screw conveyors 68 and 84. As the photosensitive drum 24 turns past
the cleaning blade 64, remaining toner is removed and drops into
the toner collection chamber 66. Screw conveyor 68 brings this
toner to the pick-up station 78 at the lower end of the channel 72,
as shown in FIG. 10A. The belt conveyor 74 carries the toner upward
toward the pulley 76 as shown in FIG. 10B. At the discharge station
80, the toner carried by the belt conveyor 74 drops into the toner
delivery chamber 82 as shown in FIG. 10C, and is fed by screw
conveyor 84 to a more central part of the toner delivery chamber
82. From there, the toner falls back into the developing unit 28,
to be picked up by the supply roller 36 and supplied again to the
developing roller 34.
As pointed out above, the invented toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism does not require the width of
the printing process cartridge 58 to be increased. The toner
.[.recycling.]. .Iadd.transporting .Iaddend.mechanism in the first
embodiment is also easier to assemble than the conventional toner
.[.recycling.]. .Iadd.transporting .Iaddend.mechanism, because the
belt conveyor 74 is driven by a single pulley 76 instead of a worm
gear train. The problem of thrust that was present in the worm gear
train is also eliminated, so printing is more regular.
Next, a second embodiment will be described.
Referring to FIG. 11, the belt conveyor 74 in the second embodiment
has teeth 90 that project at an angle in the direction of motion
(arrow B) of the belt conveyor 34. These teeth 90 engage the teeth
of a belt driving gear 92 which turns in the direction of arrow D
and drives the belt conveyor 74 around the channel 72. By pushing
against the teeth 90 of the belt conveyor 74, the belt driving gear
92 pulls the belt conveyor 74 downward in the drawing. The natural
stiffness of the belt conveyor 74 also transmits the pushing force
of the belt driving gear 92 forward, so that the belt conveyor 74
is both pushed and pulled around the channel 72.
The belt driving gear 92 also drives an idle gear 94, which drives
a gear 96 that turns the screw conveyor 84. The pulley 98 at the
top of the channel 72 turns freely. The purpose of the pulley 98 in
the second embodiment is not to drive the belt conveyor 74, but to
enable the belt conveyor 74 to negotiate the sharp turn at the top
of the channel 72 without friction.
FIG. 12 shows how the belt driving gear 92 is driven. The
photosensitive drum 24 is turned by a motor (not visible) as in the
first embodiment. A gear 100 at one end of the shaft of the
photosensitive drum 24, opposite from the end at which the toner
.[.recycling.]. .Iadd.transporting .Iaddend.mechanism is disposed,
engages a similar gear 102 at the end of the shaft of the
developing roller 34, so that the rotation of the photosensitive
drum 24 also turns the developing roller 34. The driving torque is
transmitted through the shaft of the developing roller 34 to
another gear 104. Gear 104 drives an idle gear 106, which drive a
gear 108 attached to the shaft of the supply roller 36. The
photosensitive drum 24, developing roller 34, and supply roller 36
turn in the directions indicated by arrows E, F, and G.
The gear 108 attached to the shaft of the supply roller 36 also
drives a gear 110 attached to the shaft 112 of the belt driving
gear 92 in the toner .[.recycling.]. .Iadd.transporting
.Iaddend.mechanism. An idle gear 113 is provided between the gears
108 and 110, and the rotation of gear 108 is transmitted to gear
110 through idle gear 113, so that gear 110 turns in the direction
of arrow H. The belt driving gear 92 is thereby driven in the
direction of arrow D.
FIG. 13 is an enlarged view of the belt conveyor 74, showing the
shape of the teeth 90. The outer face 114 of the teeth preferably
has a convex involute shape against which the teeth of the belt
driving gear 92 can press without friction. The inner face 116 has
a concave involute shape, generally following the contour of the
outer face 114.
Referring to FIG. 14, the shape of the teeth 90 of the belt
conveyor 74, angled in the forward direction, enables toner to be
efficiently transported vertically upward. If the teeth of the belt
conveyor 74 were to have a symmetrical shape, vertical transport
would be less efficient; toner would fall back, as illustrated in
FIG. 15.
Referring to FIG. 16, the shape of the inner face 116 of the teeth
90 is also suitable for scooping up toner in the toner collection
chamber 66. As the belt conveyor 74 turns within the channel 72,
scooping action begins when the inner end of a booth 90 is lower
than the outer end. The sloping inner face 116 of the teeth 90
permits scooping to being earlier than would be possible with a
symmetrically shaped tooth 118.
Referring again to FIGS. 11 and 13, the sloping outer surface 114
of the teeth 90 is also an advantage at the discharging station 80.
This surface 114 slopes downward at the discharge station 80,
allowing toner to fall freely into the toner delivery chamber
82.
By enabling the belt conveyor 74 to transport and discharge toner
efficiently, without friction between the belt conveyor 74 and belt
driving gear 92, the second embodiment reduces the torque load on
the motor, contributing to quieter operation of the printer, more
uniform driving of the photosensitive drum 24, and thus more
uniform printed output.
The belt driving gear 92 need not be a gear with involute teeth; a
sprocket wheel of the type used to drive an automotive timing belt
can be used, or any other type of toothed wheel can be used, with
suitable modification to the shape of the teeth 90 of the belt
conveyor 74.
Next, a third embodiment will be described.
Referring to FIG. 17, the channel 72 in the third embodiment has an
interior groove 120. The groove 120 is disposed in the floor of the
channel 72, and extends around the entire length of the channel 72,
adjacent the inner wall of the channel 72.
Referring to FIG. 18, the belt conveyor 74 in the third embodiment
is similar to the belt conveyor 74 in the second embodiment, with
teeth 90 angled toward the intended direction of motion of the belt
conveyor 74, but has an additional longitudinal rib 122 on one
side. The longitudinal rib 122 extends for the entire length of the
belt conveyor 74. The longitudinal rib 122 may be thinner than the
body 124 of the belt conveyor 74, as shown in FIG. 18.
Alternatively, the longitudinal rib 122 may have the same thickness
as the body 124 of the belt conveyor 74.
Referring to the sectional view in FIG. 19, when the belt conveyor
74 is correctly oriented in the channel 72, the longitudinal rib
122 fits into the groove 120. The side frame or toner
.[.recycling.]. .Iadd.transporting .Iaddend.portion 70 has a side
cover 126 that fits snugly against the side frame or toner
.[.recycling.]. .Iadd.transporting .Iaddend.portion 70 when the
belt conveyor 74 is installed in the correct orientation.
Referring to FIG. 20, if the belt conveyor 74 is installed in the
wrong orientation, the longitudinal rib 122 projects above the
surface of the side frame or toner .[.recycling.].
.Iadd.transporting .Iaddend.portion 70, so that a gap C is left
between the side cover 126 and the side frame or toner
.[.recycling.]. .Iadd.transporting .Iaddend.portion 70. When the
printing process cartridge 58 is assembled, if the belt conveyor 74
is mistakenly installed in the wrong orientation, the gap C makes
the mistake obvious. The side cover 126 cannot be attached to the
side frame or toner .[.recycling.]. .Iadd.transporting
.Iaddend.portion 70 until the mistake is corrected. Assembly errors
are thus avoided. The third embodiment assures that when the
printing process cartridge 58 is assembled, the teeth 90 of the
belt conveyor 74 are correctly oriented for scooping and
transporting toner, and are not oriented in the reverse direction,
which would render the belt conveyor 74 ineffective for the
scooping and transport of toner.
Next, a fourth embodiment will be described. The fourth embodiment
is similar to the third embodiment, except for the stationary shaft
of the idle gear 94.
Referring to FIG. 21, the stationary shaft 128 of the idle gear is
made of the same material as the side frame or toner
.[.recycling.]. .Iadd.transporting .Iaddend.portion 70, and forms
one part of the side frame or toner .[.recycling.].
.Iadd.transporting .Iaddend.portion 70. The idle gear 94 itself may
also be made of the same material.
The stationary shaft 128 fits into a central hole of the idle gear
94, as indicated by the dotted line in FIG. 22, permitting the idle
gear 94 to turn freely, as indicated by arrow J. The sides of the
stationary shaft 128 have a plurality of wedge-shaped grooves 132
(two grooves in the drawing), which are comparatively wide at the
end 134 not attached to the side frame or toner .[.recycling.].
.Iadd.transporting .Iaddend.portion 70, and are narrower at the
attached end.
During printing, grains of toner or other foreign matter may find
their way into the space between the idle gear 94 and its
stationary shaft 128. The rotary motion of the idle gear 94 in
direction J rolls these grains of foreign matter around the
stationary shaft 128 in the direction of arrow K in FIG. 22, so
that in a short time they drop into the grooves 132 in the shaft
128. As foreign matter collects in these grooves 132, the rotation
of the idle gear 94 forces the foreign matter against the slanted
side faces 136 of the grooves, thereby causing the foreign matter
to slide in the direction of arrow L toward the free end 134 of the
shaft 128. Foreign matter reaching the end 134 of a groove 132 can
drop out into, for example, a passage provided in the side frame or
toner .[.recycling.]. .Iadd.transporting .Iaddend.portion 70, which
will be described in a later embodiment.
By providing an escape route for foreign matter caught between the
idle gear 94 and its stationary shaft 128, the grooves 132 prevent
foreign matter from accumulating and causing friction between the
idle gear 94 and shaft 128. The torque load on the motor that
drives the photosensitive drum 24 and the toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism is accordingly not increased
due to such friction, and printing irregularities that might be
caused by such friction are avoided.
Next, a fifth embodiment will be described. The fifth embodiment is
similar to the fourth embodiment, except for the groove pattern on
the stationary shaft 128 of the idle gear 94.
Referring to FIG. 23, in the fifth embodiment, the stationary shaft
128 in the fifth embodiment has a groove 138 that follows a
counterclockwise helical path toward the end 140 of the shaft that
is not attached to the side frame 70. This helical groove 138
serves the same purpose as the grooves in the fourth embodiment. If
particles of toner or other foreign matter enter the space between
the idle gear 94 and stationary shaft 128, they are carried in the
direction of arrow K by the rotation of the idle gear 94 until they
drop into the helical groove 138. Contact with the rear side wall
142 of the helical groove 138 then pushes the foreign matter toward
the free end 140 of the shaft, to be discharged into an appropriate
passage.
The effect of the fifth embodiment is similar to the effect of the
fourth embodiment: friction between the idle gear 94 and its
stationary shaft 128 is avoided, a steady torque load is maintained
on the driving motor, and printing irregularities are
prevented.
Next, a sixth embodiment will be described. The sixth embodiment is
similar to the fifth embodiment, but locates the helical groove on
the inner surface of the idle gear 94 instead of the outer surface
of its shaft.
Referring to FIG. 24, the idle gear 94 in the sixth embodiment has
a helical groove 144 that follows a clockwise helical path around
the inner surface 146 of the idle gear 94, from the end of the idle
gear 94 adjacent the side frame 70 to the opposite end 148. The
outer surface of the stationary shaft 128 is smooth. If particles
of foreign matter enter the space between the idle gear 94 and
shaft 128, they are carried into the helical groove 144, then
carried toward the end 148 of the idle gear 94 by contact with the
rear side wall 150 of the helical groove 144, and thus discharged
into an appropriate passage.
The sixth embodiment has the same effects as the fourth and fifth
embodiments in reducing friction between the idle gear 94 and the
shaft 128, maintaining a steady torque load on the driving motor,
and preventing printing irregularities.
Next, a seventh embodiment will be described. The seventh
embodiment provides for the return of toner from the belt driving
gear 92 to the belt conveyor 74. The seventh embodiment also
provides a passage for toner discharged from between the idler gear
94 and its stationary shaft in the fourth, fifth, and sixth
embodiments.
Referring to FIG. 25, this passage 152 starts below the belt
driving gear 92, extends generally parallel to the channel 72 for a
distance, then joins the channel 72 at a point from which the
channel 72 slopes downward toward the toner collection chamber
66.
As described in the preceding embodiment, the belt conveyor 74
scoops up toner from the toner collection chamber 66 at the pick-up
station 78, carries the toner to the discharging station 80, and
discharges the toner into the toner delivery chamber 82. Some of
the toner, however, adheres to the belt conveyor 74 and fails to be
discharged. Some of this adhering toner is picked up by the teeth
of the belt driving gear 92 when they engage the teeth of the belt
conveyor 74, and adheres to the teeth of the belt driving gear 92.
This adhering toner then falls from the belt driving gear 92 into
the passage 152, is returned to the channel 72, is picked up again
by the belt conveyor 74, and is carried into the toner collection
chamber 66.
The passage 152 in the seventh embodiment prevents toner from
accumulating in the space around the belt driving gear 92, where
such toner might clog the teeth of the belt driving gear 92 and
generally interfere with the rotation of this gear 92. By
preventing such accumulation of toner, the seventh embodiment
contributes to the maintenance of a steady torque load on the
driving motor and the prevention of printing irregularities.
Next, an eighth embodiment of the invention will be described.
Referring to FIG. 26, in place of the pulley 76 and screw conveyor
84 of the first embodiment, the eighth embodiment has a toothed
screw conveyor 154 extending into the toner delivery chamber 82 in
substantially the same position as the screw conveyor 84 of the
first embodiment. The toothed screw conveyor 154 comprises a shaft
156 and a helical screw 158, with teeth 160 extending from the
outer edges of the helical screw 158 at one end. These teeth 160
engage lateral ribs 162 on the belt conveyor 74.
FIG. 27 shows a perspective view of the toothed screw conveyor 154.
The teeth 160 are disposed at the end of the helical screw 158,
where the helical screw 158 meets the belt conveyor 74.
During printing, the shaft 156 of the toothed screw conveyor 154 is
driven in the direction of arrow M in FIG. 26 by a gear train not
shown in the drawing. The teeth 160 mesh with the lateral ribs 162
and the belt conveyor 74 is driven in the direction of arrow B,
carrying toner from the toner collection chamber 66 to the toner
delivery chamber 82. The helical screw 158 then carries the toner
to the appropriate position in the toner delivery chamber 82 for
delivery to the developing unit 28.
By replacing the pulley 76 and screw conveyor 84 of the first
embodiment with a single toothed screw conveyor 154, the eighth
embodiment reduces number of parts and hence the cost of the
printing process cartridge 58. The cartridge 58 also becomes easier
and thus less expensive to assemble.
Next, a ninth embodiment will be described. Referring to FIG. 28,
the ninth embodiment has the same configuration as the first
embodiment, but with an additional projection 164 on the outer wall
of the channel 72 just above the discharging station 80. This
projection 164 interferes slightly with the belt conveyor 74, by
brushing against the lateral ribs of the belt conveyor 74, for
example, thereby causing vibrations that loosen toner from the belt
conveyor 74, so that the toner does not adhere to the belt conveyor
74 but falls into the toner delivery chamber 82. By reducing the
amount of toner that fails to be released at the discharging
station 80, the ninth embodiment enables the toner .[.recycling.].
.Iadd.transporting .Iaddend.mechanism to operate more
efficiently.
Next, a tenth embodiment will be described. Referring to FIG. 29,
the tenth embodiment has the same configuration as the first
embodiment, but with the addition of a flexible-blade 166 that
extends into the channel 72 just above the discharging station 80.
This flexible blade 166 serves the same purpose as the projection
in the ninth embodiment, slightly interfering with the belt
conveyor 74 and thereby causing vibrations that loosen toner from
the belt conveyor 74, so that more of the toner falls into the
toner delivery chamber 82 and less toner adheres to the belt
conveyor 74.
The preceding embodiments can be combined in various ways not
explicitly mentioned above. For example, the projection 164 of the
ninth embodiment or the flexible blade 166 of the tenth embodiment,
can be combined with any of the preceding embodiments.
All of the embodiments described above have the advantages
mentioned in the first embodiment. The width of the printing
process cartridge 58 is reduced because the belt conveyor 74 is
disposed in a channel 72 that loops around the ends of the shafts
of existing rollers in the printing process cartridge 58, without
extending beyond the ends of these shafts. No worm gear is
required, so the load on the driving motor is reduced, and motion
irregularities are avoided. In addition, the number of parts in the
toner .[.recycling.]. .Iadd.transporting .Iaddend.mechanism is
reduced, so the cost of the printing process cartridge 58 is
reduced, including both the materials cost and the cost of
assembly.
Those skilled in the art will recognize that other embodiments are
possible within the scope claimed below.
* * * * *