U.S. patent application number 12/466241 was filed with the patent office on 2009-11-19 for image forming apparatus.
This patent application is currently assigned to KONICA MINOLTA BUSINESS TECHNOLOGIES, INC.. Invention is credited to Kunihiro KAWACHI, Kyoichi MIZUNO.
Application Number | 20090283955 12/466241 |
Document ID | / |
Family ID | 41315424 |
Filed Date | 2009-11-19 |
United States Patent
Application |
20090283955 |
Kind Code |
A1 |
KAWACHI; Kunihiro ; et
al. |
November 19, 2009 |
IMAGE FORMING APPARATUS
Abstract
An image forming apparatus includes: an image forming section
that forms a toner image on a sheet; a fixing section that fixes
the toner image on the sheet; a sheet conveyance path that branches
into a first sheet conveyance path and a second sheet conveyance
path downstream of the fixing section; a blowing section that
guides the sheet to the first sheet conveyance path or to the
second sheet conveyance path by blowing air to the sheet; and a
controller that controls the blowing air of the blowing
section.
Inventors: |
KAWACHI; Kunihiro; (Tokyo,
JP) ; MIZUNO; Kyoichi; (Tokyo, JP) |
Correspondence
Address: |
CANTOR COLBURN, LLP
20 Church Street, 22nd Floor
Hartford
CT
06103
US
|
Assignee: |
KONICA MINOLTA BUSINESS
TECHNOLOGIES, INC.
Tokyo
JP
|
Family ID: |
41315424 |
Appl. No.: |
12/466241 |
Filed: |
May 14, 2009 |
Current U.S.
Class: |
271/3.23 ;
271/3.14 |
Current CPC
Class: |
B65H 2515/342 20130101;
B65H 2406/122 20130101; B65H 2513/42 20130101; B65H 2513/42
20130101; B65H 2515/342 20130101; B65H 2801/06 20130101; B65H 29/58
20130101; B65H 2220/01 20130101; B65H 2220/02 20130101 |
Class at
Publication: |
271/3.23 ;
271/3.14 |
International
Class: |
B65H 5/22 20060101
B65H005/22 |
Foreign Application Data
Date |
Code |
Application Number |
May 19, 2008 |
JP |
2008-130550 |
Claims
1. An image forming apparatus comprising: (a) an image forming
section that forms a toner image on a sheet; (b) a fixing section
that fixes the toner image on the sheet; (c) a sheet conveyance
path that branches into a first sheet conveyance path and a second
sheet conveyance path downstream of the fixing section; (d) a
blowing section that guides the sheet to the first sheet conveyance
path or to the second sheet conveyance path by blowing air to the
sheet; and (e) a controller that controls the blowing air of the
blowing section.
2. The image forming apparatus of claim 1, wherein the blowing
section comprises a first blowing member and a second blowing
member which blow air of the blowing section, wherein the first and
second blowing members are arranged to face each other.
3. The image forming apparatus of claim 2, wherein each of the
first and second blowing members comprises a slit-shaped air
blowing outlet.
4. The image forming apparatus of claim 2, wherein the first and
second blowing members are arranged so that blown air blowing out
each of of the first blowing member and the second blowing member
advances toward a leading edge of the sheet after hitting a surface
of the advancing sheet.
5. The image forming apparatus of claim 2, wherein the first
blowing member comprises a first air amount changing section which
changes an amount of blown air blowing out of the first blowing
member, and the second blowing member comprises a second air amount
changing section which changes an amount of blown air blowing out
of the second blowing member.
6. The image forming apparatus of claim 5, wherein each of the
first and second air amount changing sections comprises an opening
area adjusting member which changes an opening area at the air
blowing outlet, and changes the amount of the blown air blowing out
of the air blowing outlet by moving the opening area adjusting
member.
7. The image forming apparatus of claim 2, wherein the blowing
section comprises a first air valve which sends or intercepts air
blowing from the first blowing member, and a second air valve which
sends or intercepts air blowing from the second blowing member.
8. The image forming apparatus of claim 7, wherein the controller
calculates positional information of a leading edge of the conveyed
sheet on the basis of a signal sent from a sheet detection sensor
that detects the leading edge of the sheet, determines a timing of
the sending air or the intercepting air on the basis of the
calculated positional information, and changes the amount of the
air blowing out of each of the first and second air amount changing
sections.
9. The image forming apparatus of claim 1, further comprising: a
sheet ejection tray which receives the sheet ejected from the
apparatus; and a re-feeding section through which the sheet having
an image on a front side thereof is re-fed for forming an image on
a rear side, wherein the first sheet conveyance path is a
conveyance path through which the sheet is conveyed to the sheet
ejection tray, and the second sheet conveyance path is a conveyance
path through which the sheet is conveyed to the re-feeding
section.
10. The image forming apparatus of claim 1, further comprising: a
sheet ejection tray which receives the sheet ejected from the
apparatus; and a sheet reversing section by which a front and rear
sides of the sheet are reversed, wherein the first sheet conveyance
path is a conveyance path through which the sheet is conveyed to
the sheet ejection tray, and the second sheet conveyance path is a
conveyance path through which the sheet is conveyed to the sheet
reversing section.
Description
[0001] This application is based on Japanese Patent Application No.
2008-130550 filed on May 19, 2008, which is incorporated hereinto
by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to an advancing direction
switching section for a sheet that is in a sheet conveyance path of
an image forming apparatus.
[0003] In general, an image forming apparatus of an
electrophotographic type transfers a toner image visualized through
toner development onto a sheet, and fixes the toner image on a
sheet by pressing and heating the sheet onto which the toner image
has been transferred with a fixing section.
[0004] The aforesaid sheet which has been subjected to fixing
processing by the aforesaid fixing section is guided to the first
sheet conveyance path or to the second sheet conveyance path, by a
sheet conveyance path switching section that switches advancing
directions for a sheet.
[0005] The aforesaid first sheet conveyance path is, for example, a
sheet conveyance path through which the aforesaid sheet is sent to
a sheet ejection tray of the image forming apparatus, or to a sheet
finisher that is connected to the downstream side, while, the
aforesaid second sheet conveyance path is, for example, a sheet
conveyance path through which the aforesaid sheet is sent to a
sheet reversing device, or to a sheet re-feeding device that is for
forming an image on the reverse side of the aforesaid sheet.
[0006] Many of the aforesaid sheet conveyance path switching
sections are constructed so that the aforesaid sheet may be guided
to the prescribed sheet conveyance path by moving the sheet guide
member on which a leading edge portion of the sheet rubs, and
therefore by regulating the advancing direction of the sheet (for
example, see Unexamined Japanese Patent Application Publication No.
2006-330250).
[0007] The sheet conveyance path switching section of this kind can
be realized in a simple structure, and it is characterized to be
low in cost, but it gives strong stress to the sheet, because the
sheet immediately after fixing processing comes in pressure contact
with a guide member to be bent.
[0008] Further, there are sometimes caused problems wherein toner
and wax on the sheet surface stick to the aforesaid sheet guide
member, and the sticking toner and wax stick again to the sheet
because an image surface of the sheet heated by fixing processing
rubs against the sheet guide member.
SUMMARY OF THE INVENTION
[0009] The invention has been achieved in view of the situations
mentioned above, and its object is to realize an image forming
apparatus having a sheet conveyance path that branches into the
first sheet conveyance path and the second sheet conveyance path at
the downstream side of a fixing unit, wherein there is provided an
air sending section that switches the sheet conveyance path for the
sheet to the first conveyance path or to the second conveyance
path, by blowing air against the sheet.
[0010] An aspect for attaining the aforesaid object is as
follows.
[0011] An image forming apparatus characterized in that an image
forming section that forms a toner image on a sheet, a fixing
section that fixes the toner image on the sheet, a sheet conveyance
path that branches into the first sheet conveyance path and the
second sheet conveyance path at the downstream side of the
aforesaid fixing section, a blowing section that guides the
aforesaid sheet to the first sheet conveyance path or to the second
sheet conveyance path by blowing air to the sheet and a controller
that controls blowing of the blowing section, are provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a conceptual diagram of a conventional image
forming apparatus.
[0013] FIG. 2 is a conceptual diagram of an image forming apparatus
in the present embodiment.
[0014] FIG. 3 is a block diagram showing relationship for
controlling an image forming apparatus.
[0015] FIG. 4 is a diagram illustrating relationship of arrangement
for a sheet conveyance path and a blowing member.
[0016] FIG. 5 is a block diagram illustrating the structure of the
blowing section.
[0017] Each of FIGS. 6(a)-6(d) shows an example of an air amount
changing section.
[0018] FIG. 7 is a flow chart showing a flow of blowing
control.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] An example of the embodiment of the invention will be
explained as follows based on drawings. Incidentally, the invention
is not limited to the present example.
[0020] FIG. 1 is a conceptual diagram of a conventional color image
forming apparatus G.
[0021] The color image forming apparatus G exemplified in the
drawing is one that is called a tandem type color image forming
apparatus wherein a plurality of photoconductors 31Y, 31M, 31C and
31K are arranged in tandem to face a single intermediate transfer
belt 41, and a full-color image is formed.
[0022] This color image forming apparatus G is equipped, on its
upper portion, with automatic document feeder ADF.
[0023] Documents D placed on document table 103 of the automatic
document feeder ADF are separated to be a single sheet to be sent
out to a document conveyance path, and is conveyed by conveyance
drum 108.
[0024] An image of the documents D during conveyance is read by
document reading section 1 at document image reading position RP.
The document D which has been finished in terms of image reading is
ejected to document ejection tray 107 by a plurality of conveyance
guides and by document ejection roller 105.
[0025] Image forming apparatus G is composed of document reading
section 1, exposure sections 2Y, 2M, 2C and 2K, image forming
sections 3Y, 3M, 3C and 3K, intermediate transfer section 4, fixing
section 5, reversing sheet ejection section 6, sheet re-feeding
section 7, sheet feeding section 8 and control section C which are
housed in a single casing.
[0026] The document reading section 1 illuminates a document image
with lamp L at document image reading position RP, and guides its
reflected light with first mirror unit 11, second mirror units 12,
and lens 13, to cause the reflected light to form an image on a
light-receiving surface of charge coupled device image sensor
CCD.
[0027] Image signals obtained through photoelectric conversion by
charge coupled device image sensor CCD undergo processes including
A/D conversion by image reading control section 14, shading
correction, and compression, which are stored in a memory of
control section C as image data.
[0028] The aforesaid image data stored in the memory undergo
appropriate image processing based on conditions established by a
user, and output image data are created.
[0029] Each of exposure sections 2Y, 2M, 2C and 2K is composed of a
laser light source, a polygon mirror and a plurality of lenses, and
it creates a laser beam.
[0030] Each of exposure sections 2Y, 2M, 2C and 2K conducts
scanning exposure by a laser beam on the surface of each of
photoconductors 31Y, 31M, 31C and 31K representing constituent
elements for image forming sections 3Y, 3M, 3C and 3K,
corresponding to output information outputted based on the
aforesaid output image data.
[0031] A latent image is formed on each of the photoconductors 31Y,
31M, 31C and 31K through the aforesaid scanning exposure by a laser
beam.
[0032] Image forming section 3Y is composed of photoconductor 31Y,
and of main charging section 32Y, developing section 33Y, first
transfer roller 34Y and cleaning section 35Y which are arranged
around the photoconductor 31Y. The same is equally true of the
photoconductors 31M, 31C and 31K.
[0033] Latent images on the photoconductors 31Y, 31M, 31C and 31K
are developed by respective developing sections 33Y, 33M, 33C and
33K which correspond to the aforesaid photoconductors, whereby,
each toner image is formed on each photoconductor.
[0034] The aforesaid toner images formed respectively on
photoconductors 31Y, 31M, 31C and 31K are transferred one after
another at prescribed positions on intermediate transfer belt 41
representing an intermediate transfer body, by first transfer
rollers 34Y, 34M, 34C and 34K of intermediate transfer device
4.
[0035] Toner remaining on a surface of the photoconductor from
which a toner image has been transferred is removed by each of
cleaning sections 35Y, 35M, 35C and 35K.
[0036] On the other hand, the aforesaid toner image transferred
onto the aforesaid intermediate transfer belt 41 is conveyed by
second transfer roller 42 from each of trays PG1, PG2 and PG3 of
sheet feeding section 8, or from sheet feeding device S1, and is
transferred onto sheet P that is fed out after its timing is
controlled by sheet feeding roller 81.
[0037] A surface of the intermediate transfer belt 41 on which the
transfer of a toner image onto sheet P has been finished is cleaned
by belt cleaning section 43, to be ready for the succeeding image
transfer.
[0038] On the other hand, sheet P carrying a toner image is
conveyed to fixing section 5 where the toner image is fixed on the
sheet P when it is pressed and heated.
[0039] Sheet P that has been finished in terms of fixing processing
by fixing section 5 is guided by sheet conveyance path switching
section 6 in terms of its advance path, and is ejected to sheet
ejection tray 61.
[0040] When ejecting sheet P after reversing inside out, the sheet
P is guided downward temporarily by sheet ejection guide 62, then,
the sheet P is reversed after causing sheet ejection reversing
roller 63 to interpose a trailing edge of sheet P, and the sheet is
guided to sheet ejection roller 64 by sheet ejection guide 62 to be
ejected.
[0041] Incidentally, when forming an image also on the reverse of
sheet P, sheet P that is finished in terms of image fixing on the
obverse is conveyed to sheet re-feeding section 7 located below by
sheet guide member 62, and the sheet P is reversed by sending it
reversely after causing re-feed reversing roller 71 to interpose a
trailing edge, thus, the sheet P is fed out to sheet re-feeding
conveyance path 72 to be ready for image forming on the
reverse.
[0042] FIG. 2 is a conceptual diagram of image forming apparatus G1
in the present embodiment.
[0043] Though the image forming apparatus G1 is different from
color image forming apparatus G in terms of a structure of sheet
conveyance switching section 6 at downstream side of a fixing
section, other points are the same. Thus, the overall explanation
will be omitted.
[0044] FIG. 3 is a block diagram showing relationship for
controlling image forming apparatus G1.
[0045] Control section C1 of image forming apparatus G1 is a
computer system having therein CPU, memory M1, an operation unit,
I/O port, an interface for communication and drive circuit.
[0046] The control by the control section C1 is carried out by
performing the prescribed programs stored in memory M1.
[0047] Further, the control section C1 is connected to a network to
be capable of exchanging information with other information
exchange equipment.
[0048] In the present drawing, meanwhile, descriptions of blocks
which are not related directly to the explanation of the present
embodiment are omitted.
[0049] FIG. 4 is a diagram illustrating relationship of arrangement
for sheet conveyance path 100 and blowing members 210 and 220.
[0050] The sheet conveyance path 100 is one arranged at the
downstream side of fixing section 5, and it is a sheet conveyance
path through which sheet P that has been finished in terms of
fixing processing and has been detected by sheet detection sensor
SP in terms of its leading edge is guided to the first sheet
conveyance path 101 or to the second sheet conveyance path 102.
[0051] At a point where the aforesaid sheet conveyance path 100 is
branched into the first sheet conveyance path 101 and to the second
sheet conveyance path 102, there are arranged first blowing member
210 and second blowing member 220 both representing a blowing
nozzle that blows air against sheet P, in a way to face each
other.
[0052] Meanwhile, in an example shown in FIG. 2, a conveyance path
for conveying sheet P toward sheet ejection tray 61 corresponds to
the first sheet conveyance path, and a conveyance path for
conveying sheet P toward sheet ejection reversing roller (also
referred to as sheet reversing section) 63 or toward sheet
re-feeding section 7 corresponds to the second sheet conveyance
path.
[0053] Furthers with respect to a direction of the blowing nozzle,
it is not perpendicular to a plane of sheet P, but it is oblique so
that a tip of the nozzle may be in the advancing direction of sheet
P as shown in the drawing. By providing the inclination of this
kind, air can flow in the advancing direction of sheet P, and
conveyance of the sheet is stabilized.
[0054] Further, the first blowing member and the second blowing
member are arranged so that blown air blowing out of the first
blowing member and the second blowing member may advance in the
direction toward the leading edge of the sheet after hitting the
surface of the advancing sheet.
[0055] FIG. 5 is a block diagram illustrating the structure of
blowing section 200.
[0056] The blowing section 200 is composed of first blowing member
210, air valve 211, second blowing member 220, air valve 221, air
tank 230, air pump 240 and air duct 260.
[0057] The air pump 240 sends air so that air pressure in the air
tank 230 may keep prescribed pressure.
[0058] Air in the aforesaid air tank is sent to the first blowing
member 210 or to the second blowing member 220, when air valve 211
or air valve 212 which is opened or closed by instruction signals
219 or 229 of control section C1 is opened. Further, air sending to
the first blowing member 210 or to the second blowing member 220 is
intercepted, when the air valve 211 or the air valve 212 is
closed.
[0059] Owing to the structure mentioned above, timing of the start
of air blowing from the first blowing member 210 or the second
blowing member 220, or timing of interception, is controlled by
control section C1.
[0060] On apical portions respectively of the first blowing member
210 and the second blowing member 220, there are respectively
provided the first air amount changing section 251 whose position
is changed by instruction signal 218 of control section C1 and the
second air amount changing section 252 whose position is changed by
instruction signal 228 of control section C1.
[0061] Namely, an amount of air blowing against sheet P from
forefronts of the first blowing member 210 and the second blowing
member 220 per unit time is controlled when the control section C1
controls the first air amount changing section 251 and the second
air amount changing section 252.
[0062] Each of FIGS. 6(a)-6(d) shows an example of an air amount
changing section. Meanwhile, the structure of the first air amount
changing section 251 is the same as that of the second air amount
changing section 252.
[0063] FIG. 6(a) is a conceptual diagram of the first blowing
member 210, and air that is conveyed through air duct 260 blows out
in the direction of arrow "f" from slit-shaped air blowing outlet
259 of the first blowing member 210.
[0064] The first air amount changing section 251 is provided on the
blowing outlet of the first blowing member 210. Each of FIGS. 6(b),
6(c) and 6(d) is an example of the first are amount changing
section 251.
[0065] FIG. 6(b) is an example wherein an amount of air that hits
sheet P is changed when member 255 having small holes formed in a
staggered pattern is moved to a blowing outlet of the first blowing
member 210.
[0066] Further, FIG. 6(c) is an example wherein an amount of air
that hits sheet P is changed when indented member 256 is moved at a
blowing outlet of the first blowing member 210.
[0067] Further, FIG. 6(d) is an example wherein an amount of air
that hits sheet P is changed when member 257 that is opened and
closed symmetrically is caused to open and close at a blowing
outlet of the first blowing member 210.
[0068] Each of the aforesaid members 255, 256 and 257 is called an
opening area adjusting member.
[0069] FIG. 7 is a flow chart showing a flow of blowing
control.
[0070] Control of blowing is one wherein sheet P advancing to sheet
conveyance path 100 is guided to the first sheet conveyance path
101 or to the second sheet conveyance path 102 by spraying air
against sheet P following specifications of a job established in
advance, and sheet P that advances further receives blowing to cool
an image plane.
[0071] After the leading edge of sheet P is detected by sheet
detection sensor SP (step S1: Y), sheet conveyance path selection
information that is determined by specifications of the job
established on image forming apparatus G1 is acquired. Further,
sheet leading edge position information that is a distance by which
the leading edge of sheet P advances from a position of the sheet
detection sensor SP is calculated one after another from a
conveyance speed of sheet P (step S2).
[0072] After it becomes clear that the leading edge of sheet P has
arrived at the position established in advance by the aforesaid
calculated sheet leading edge position information (step S3: Y),
the sheet P is judged whether it is sheet P to be sent to the first
sheet conveyance path 101 or not, referring to the aforesaid
acquired sheet conveyance path selection information (step S4).
[0073] If the sheet P is one to be sent to the first sheet
conveyance path, second air valve 212 is opened so that air may
blow out of second blowing member 220 positioned below the sheet P
(step S5). An amount of air blowing out per unit time is determined
by the second air amount changing section 252.
[0074] When a leading edge portion of sheet P is guided to the
first sheet conveyance path 101 by air blowing out of the second
blowing member 220 and the leading edge of sheet P arrives at an
air amount changing position established in advance (step 6: Y), an
amount of air blowing out of the second blowing member 220 is
reduced (step S7).
[0075] A change of an amount of air blowing out of the second
blowing member 220 of this kind reduces problems that contact
between an image surface of sheet P and a sheet guide member of the
first sheet conveyance path is weakened, toner and wax on the sheet
surface stick to the aforesaid sheet guide member.
[0076] Meanwhile, in the example stated above, a leading edge
portion of sheet P is guided by air blowing out of the second
blowing member 220 to the first sheet conveyance path 101, for easy
understanding of the explanation. However, it is preferable to
construct so that air may blow out of both the first blowing member
210 and the second blowing member 220, and a leading edge portion
of sheet P may be guided to the first sheet conveyance path 101 by
the difference between an amount of air from the first blowing
member 210 and that of air from the second blowing member 220.
[0077] By constituting as stated above so that both sides of sheet
P are constantly hit by air, air flows constantly on an image
surface of sheet P, thus, a toner image heated in fixing device 5
is cooled rapidly, rubbing between sheet P and a sheet guide member
is reduced, and a problem that toner and wax on the surface of the
sheet stick to the sheet guide member is further reduced.
[0078] After the trailing edge of sheet P is detected by sheet
detection sensor SP (step S8: Y), or after the passage of
prescribed time since the detection, an air valve that has been
opened is closed (step 12) to finish the routine.
[0079] On the other hand, in step S4, when sending sheet P to
second sheet conveyance path 102 (step S4: N), the first air valve
211 is opened (step S9) so that air may blow out of the first
blowing member 210 that is located above the sheet P. Meanwhile, an
amount of air emitted per unit of time is determined by the first
air amount changing section 251.
[0080] When a leading edge portion of sheet P is guided to the
second sheet conveyance path 102 by air blowing out of the first
blowing member 210 and the leading edge arrives at a position for
changing an amount of air established in advance (step S10: Y), an
amount of air blowing out of the first blowing member 210 is
reduced (step S11).
[0081] In the example stated above again, a leading edge portion of
sheet P is guided by air blowing out of the second blowing member
210 to the second sheet conveyance path 102, for easy understanding
of the explanation. However, it is preferable to construct so that
air may blow out of both the first blowing member 210 and the
second blowing member 220, and a leading edge portion of sheet P is
guided to the second sheet conveyance path 102 by the difference
between an amount of air from the first blowing member 210 and that
of air from the second blowing member 220.
[0082] By constituting, as stated earlier, so that both sides of
sheet P may be constantly hit by air, air flows constantly on an
image surface of sheet P, thus, a toner image heated in fixing
device 5 and sheet P are cooled rapidly, and rubbing between sheet
P and a sheet guide member is reduced.
[0083] As a result, a problem that toner and wax on a surface of
the sheet stick to the sheet guide member, and a problem of
occurrence of curls which are caused when strong stress is applied
on overheated sheet P, are reduced.
[0084] After the trailing edge of sheet P is detected by sheet
detection sensor SP (step S8: Y), or after the passage of
prescribed time since the detection, an air valve that has been
opened is closed (step 12) to finish the routine.
[0085] In the case of switching of sheet conveyance paths in the
present embodiment in the image forming apparatus having a sheet
conveyance path that is branched into the first sheet conveyance
path and the second sheet conveyance path, at the downstream side
of the fixing device, occurrence of curls of sheets can be
suppressed, because strong stress is not applied on the sheet
immediately after fixing processing, which is different from sheet
conveyance path switching in which a sheet conveyance path is
switched by a sheet guide member.
[0086] Further, it is possible to prevent a problem that toner and
wax stick to the sheet guide member and to stick again to the
sheet, because an image surface of the sheet heated by fixing
processing does not rub strongly against the aforesaid sheet guide
member, and is further cooled by air.
* * * * *