Color image forming apparatus and color misalignment adjusting

Color image forming apparatus and color misalignment adjusting
US 20130039680A1
(19) United States
(12) Patent Application Publication (10) Pub. N0.: US 2013/0039680 A1
KUMAGAI et al.
(54)
(43) Pub. Date:
COLOR IMAGE FORMING APPARATUS AND
(52)
Feb. 14, 2013
US. Cl. ..................................................... .. 399/301
COLOR MISALIGNMENT ADJUSTING
METHOD
(57)
(76) Inventors? Yuji KUMAGAI, Osalfa (JP); Norio
ABSTRACT
According to a color image forming apparatus, a plurality of
Tomlta: Osaka (JP); Klyoshl sasohs
detection patterns respectively corresponding to a plurality of
Osaka (JP)
colors are formed from a plurality of photosensitive body
(21)
_
Appl' NO" 13/554’478
units respectively corresponding to the plurality of colors
onto a transfer member in a sub-scanning direction of the
(22)
Flled'
.
(
30
_
transfer member, intervals between detection patterns adja
Jul‘ 20’ 2012
F
)
.
A
1
.
cent to each other in the sub-scanning direction among the
t
.
P
.
.
Aug. 12 2011
’
P lurality of formed detection patterns are detected ’ and
t D t
orelgn PP lea Ion non y
a a
adjustment of color misalignment is performed based on the
(JP) ............................... .. 2011-177010
Publication Classi?cation
51
apparatus, the adjustment of color misalignment is performed
using at least tWo types of data of detection images having
Int. Cl.
G03G 15/01
detectedimervals-Theplurality ofdetectionpanemshavethe
same siZe and the same shape. In this color image forming
different intervals as data of detection imag es including the
(2006.01)
plurality of detection patterns.
81
Perform
rough adjustment
7
Perform ordinary
YES
operation
~87
Read patterns for rough
adjustment
S8
s3
Continue image formation
S4
Perform fine
89
adjustment?
85
YES
color misalignment
between colors
7
Read patterns for fine
adiustment
color misalignment
between colors
7
S14
Correct color misalignment
END
Patent Application Publication
FIG.1
Feb. 14, 2013 Sheet 1 0f 4
US 2013/0039680 A1
Patent Application Publication
Feb. 14, 2013 Sheet 2 0f 4
US 2013/0039680 A1
FIG.2
100
f 300
Main control portion
301 \
303 \
304\
Input portion
Display portion
Storage portion
Optical unit
Image Pmcessfng
Facsimile portion
operation portion
306
Network I/F
‘
f 302
f 90
Image forming f
portion
102
\ 309
305
307 f
Patent Application Publication
Feb. 14, 2013 Sheet 3 0f 4
US 2013/0039680 A1
FIGJS
310
Subfscalnning
Patterns for rough adjustment 6%
D1
//
Mgain~sc ing
dI'ECtO?
u:
3 Blocks
310
E;
I PB
PB '
FWBKHLT
——>P1_/"l(l(| HI llllllllllllllll
/
\
P2 3 P4
P3
FIGA
310
Eé—->
Patterns forfine adjustment
Subl-scalnning
<_______>d'rectlon
lllllllllllIHHIHIIIIIIHIIIIllllllll
5%
5 Blocks
310
E4
PB
'0 -u
}-u
,1 AVE/E
m
CD
*ildigglwll IIIIH IIIIHHIHIIHIHIHIIHI
PM 3 >4
D2
/
f\/ 61
Main-sc gdirecton
Patent Application Publication
Feb. 14, 2013 Sheet 4 0f 4
US 2013/0039680 A1
FIG.5
S1
Perform
NO
rough my
?
YES
Perform ordinary x 87
operation
Read patterns for rough w 82
adjustment
S8
Form pattern images
N 83
Continue image formation
S9
Detect pattern images w 84
Perform fine
adjustment?
85
Detect
®____>
color misalignment
between colors
7
YES
Read patterns for fine w
YES
adjustment
f 36
Correct color misalignment
@
Form pattern images
_
S10
’» S11
Detect pattern images ’» S12
S13
Detect
color misalignment
betweeny
YES
/ S14
Correct color misalignment
END
NO
Feb. 14, 2013
US 2013/0039680 A1
COLOR IMAGE FORMING APPARATUS AND
COLOR MISALIGNMENT ADJUSTING
METHOD
BACKGROUND OF THE INVENTION
[0001]
This application claims priority under 35 U.S.C.
§ll9 (a) on Patent Application No. 2011-177010 ?led in
Japan on Aug. 12, 2011, the entire contents of Which are
herein incorporated by reference.
[0002]
The present invention relates to a color image form
ing apparatus and a color misalignment adjusting method that
correct color misalignment of images using a plurality of
colors.
[0003]
Conventionally, in a color image forming apparatus
(hereinafter, referred to as an “image forming apparatus”), an
electrostatic latent image is formed by irradiating a photosen
tern data as the siZe of the detection pattern data increases.
Thus, in order to reduce the amount of toner consumed, it is
desirable to reduce the area of the detection patterns.
[0009] HoWever, if the area of the detection patterns is
reduced in order to reduce the amount of toner consumed, the
outline of the toner images becomes blurred, and, as a result,
the detection precision decreases. In order to avoid a decrease
in the detection precision, it is necessary to increase the siZe
of the detection patterns, but this countermeasure is problem
atic in that the amount of toner consumed cannot be sup
pressed as described above.
[0010] In order to solve the above-described problems, it is
an object of the present invention to provide a color image
forming apparatus and a color misalignment adjusting
method that can improve the detection precision While sup
pressing the amount of toner consumed.
sitive body such as a photosensitive drum With laser beams
modulated according to image data, the electrostatic latent
image formed on the photosensitive body is developed With
SUMMARY OF THE INVENTION
toner, and the toner image is formed on a transfer member
such as an intermediate transfer belt (see JP 2003-149907A
[0011] In order to achieve the above-described object, the
present invention is directed to a color image forming appa
ratus, Wherein a plurality of detection patterns respectively
(Patent Document 1), for example).
[0004] The image forming apparatus according to Patent
plurality of photosensitive body units respectively corre
Document 1 includes a plurality of image forming portions
respectively corresponding to a plurality of colors, Wherein
corresponding to a plurality of colors are formed from a
posed manner from the plurality of image forming portions to
an endless belt (transfer member), and then, the images trans
sponding to the plurality of colors onto a transfer member in
a sub-scanning direction of the transfer member, intervals
betWeen detection patterns adjacent to each other in the sub
scanning direction among the plurality of formed detection
patterns are detected, and adjustment of color misalignment is
ferred in a superimposed manner are transferred in a batch to
performed based on the detected intervals, the plurality of
images of the respective colors are transferred in a superim
a recording paper, forming a color image on the recording
detection patterns have the same siZe and the same shape, and
paper.
the adjustment of color misalignment is performed using at
[0005]
In the image forming apparatus as described in
Patent Document 1, due to factors such as misalignment
betWeen installation positions of a plurality of image forming
least tWo types of data of detection images having different
intervals as data of detection images including the plurality of
detection patterns.
portions occurring When installing the plurality of image
[0012] According to the present invention, since the adjust
forming portions, errors in the optical path length of a laser
beam, changes in the optical path, Warping of an LED func
perature, or the like, misalignment betWeen the positions of
images of the respective colors formed on the photosensitive
ment of color misalignment is performed using at least tWo
types of data of detection images having different intervals, a
plurality of adjustment choices can be provided for the adjust
ment of color misalignment. As a result, the adjustment of
color misalignment can be performed With a given level of
bodies may occur. Due to this misalignment, When transfer
precision depending on occasions such as those When per
tioning as a light source caused by the environmental tem
ring the respective colors from the plurality of photosensitive
forming initial settings or When performing maintenance
bodies in a superimposed manner, the respective colors can
not be transferred to desired positions on the endless belt, and,
therefore, color misalignment occurs on the endless belt.
[0006] In order to correct this color misalignment, conven
ment means for adjusting positional misalignment.
[0007] According to this adjustment means, detection pat
after use of the color image forming apparatus. That is to say,
the detection can be performed With an optimal level of pre
cision depending on the conditions. Furthermore, the amount
of toner consumed can be suppressed Whichever type of data
of detection images is used to perform the adjustment of color
misalignment. In a speci?c embodiment of the present inven
tion, since a plurality of types of data of detection images are
terns respectively corresponding to a plurality of colors are
used, the adjustment of color misalignment can be performed
formed on an endless belt in a sub-scanning direction by a
in a sequential or stepWise manner from rough adjustment to
?ne adjustment, and the correction of color misalignment can
tional image forming apparatuses are provided With adjust
plurality of image forming portions (speci?cally, photosen
sitive bodies). Then, the intervals betWeen detection patterns
adjacent to each other in the sub-scanning direction among
be precisely performed.
the detection patterns formed on the endless belt are detected
using light from an optical sensor such as a CCD, color
the data of detection images include tWo types of data com
misalignment at the time of development is detected using the
detected data, and the optical path length is automatically
corrected according to the color misalignment amount.
[0008] In the conventional correction of color misalign
ment as described in Patent Document 1, since toner images
for detection are formed on the transfer member (endless
belt), toner is consumed for the detection. The amount of
toner consumed increases in proportion to the detection pat
[0013]
The above-described con?guration may be such that
posed of ?rst data of detection images and second data of
detection images having an interval smaller than that of the
?rst data, and that, after the adjustment of color misalignment
using the ?rst data is performed, the adjustment of color
misalignment using the second data is performed.
[0014] According to the present invention, since the rough
adjustment of color misalignment is performed based on the
?rst data having a large interval, after Which the ?ne adjust
ment of color misalignment is performed based on the second
Feb. 14, 2013
US 2013/0039680 A1
data having a small interval, the correction of color misalign
ment can be precisely performed.
[0015] The above-described con?guration may be such that
the adjustment of color misalignment is performed based on
a preset condition using the ?rst data and the second data.
[0016]
In this case, the rough adjustment of color misalign
ment using the ?rst data can be performed based on a preset
condition (e.g., at the time of initial settings) Where the color
misalignment amount may be signi?cant, and the ?ne adjust
ment of color misalignment using the second data can be
periodically performed based on a preset condition in ordi
nary use (e.g., the time). As a result, since the rough adjust
ment of color misalignment using the ?rst data has been
adjustment to ?ne adjustment. In this case, the correction of
color misalignment can be precisely performed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019]
FIG. 1 is a schematic cross-sectional front vieW
shoWing the overall con?guration an image forming appara
tus according to an embodiment.
[0020]
FIG. 2 is a schematic block diagram shoWing essen
tial constituent components of the image forming apparatus
according to this embodiment.
[0021] FIG. 3 is a diagram shoWing detection patterns for
rough adjustment used in the adjustment of color misalign
ment according to this embodiment.
performed in advance, misalignment in the ?ne adjustment of
color misalignment using the second data is slight, and the
[0022] FIG. 4 is a diagram shoWing detection patterns for
?ne adjustment used in the adjustment of color misalignment
adjustment of color misalignment can be more precisely per
formed. On the other hand, if the adjustment of color mis
according to this embodiment.
[0023] FIG. 5 is a ?owchart for the adjustment of color
alignment using the second data is performed under, for
misalignment according to this embodiment.
example, the conditions at the time of initial settings, since the
range in Which the adjustment of color misalignment can be
performed is narroW, misalignment betWeen installation po si
tions When installing the image forming portion such as a
plurality of photosensitive body units has to be substantially
eliminated. Thus, With the technique at the time of the present
application, it is dif?cult to perform adjustment of color mis
alignment using the second data When the color misalignment
amount may be signi?cant, for example, at the time of initial
settings.
[0017]
In order to achieve the above-described object, the
present invention is further directed to a color misalignment
adjusting method of a color image forming apparatus, includ
ing: a formation step of forming a plurality of detection pat
terns respectively corresponding to a plurality of colors from
a plurality of photosensitive body units respectively corre
sponding to the plurality of colors onto a transfer member in
a sub-scanning direction of the transfer member; and an
adjustment step of detecting intervals betWeen detection pat
terns adjacent to each other in the sub-scanning direction
among the plurality of detection patterns formed in the for
DESCRIPTION OF REFERENCE NUMERALS
[0024]
[0025]
1 Light exposure unit
2 Development unit
[0026]
[0027]
[0028]
3 Photosensitive drum
4 Photosensitive body unit
5 Charging unit
[0029]
6 Intermediate transfer belt unit
[0030]
[0031]
[0032]
[0033]
[0034]
[0035]
[0036]
7 Fixing unit
8 Pre-transfer charging unit
10 Transfer roller
11a, 11b Pickup roller
12a, 12b, 12c, 12d Transport roller
13 Registration roller
21 Toner cartridge unit
[0037]
[0038]
[0039]
[0040]
61
62
63
64
Intermediate transfer belt
Drive roller
Idler roller
Intermediate transfer roller
[0041]
65 Cleaning unit
ment based on the detected intervals; Wherein the plurality of
detection patterns have the same siZe and the same shape, and
[0042]
[0043]
71 Heat roller
71a Heater
[0044]
71b Temperature detector
the adjustment of color misalignment is performed in the
adjustment step using at least tWo types of data of detection
images having different intervals as data of detection images
including the plurality of detection patterns.
[0018] According to the present invention, since the
method includes the formation step and the adjustment step,
and the adjustment of color misalignment is performed using
[0045]
72 Pressure roller
[0046]
[0047]
[0048]
[0049]
73 External heating belt
81 Paper feed tray
82 Manual paper feed tray
90 Optical unit
[0050]
[0051]
[0052]
[0053]
[0054]
91 Paper discharge tray
92 Document placement platen
100 Image forming apparatus
mation step, and performing adjustment of color misalign
at least tWo types of data of detection images having different
intervals, a plurality of adjustment choices can be provided
for the adjustment of color misalignment. As a result, the
adjustment of color misalignment can be performed With a
given level of precision depending on occasions such as those
When performing initial settings or When performing mainte
nance after use of the color image forming apparatus. That is
to say, the detection can be performed With an optimal level of
precision depending on the conditions. Furthermore, the
amount of toner consumed can be suppressed Whichever type
of data of detection images is used to perform adjustment of
color misalignment. In a speci?c embodiment of the present
invention, since a plurality of types of data of detection
images are used, the adjustment of color misalignment can be
performed in a sequential or stepWise manner from rough
102 Image forming portion
103 Paper transport system
[0055]
108 Document reading device
[0056]
[0057]
[0058]
[0059]
[0060]
[0061]
110 Apparatus main body
200 Image forming unit
300 Main control portion
301 Input portion
302 Display portion
303 Storage portion
[0062] 304 Image processing operation portion
[0063]
[0064]
305 NetWork
306 NetWork interface
[0065]
[0066]
307 Telephone line
308 Facsimile portion
Feb. 14, 2013
US 2013/0039680 A1
[0067]
309 Bus
[0083]
[0068]
310 Sensor portion
[0069]
[0070]
D1 First data
D2 Second data
are charging means for uniformly charging the surfaces of
photosensitive drums 3 to a predetermined potential, and, as
the charging units 5, charging units of contact type such as
[0071] P1, P2, P3, P4 Detection pattern
[0072]
PB Detection pattern block
[0073] S Paper transport path
In the photosensitive body units 4, charging units 5
rollers or brushes can be used as Well as those of charger type
as shoWn in FIG. 1.
[0084]
The light exposure unit 1 is con?gured as a laser
scanning unit (LSU) including a laser emitting portion and
DESCRIPTION OF THE EMBODIMENT
[0074] Hereinafter, an embodiment according to the
present invention Will be described With reference to the
drawings.
[0075]
<Description of the Overall Con?guration of the
Image Forming Apparatus>
[0076]
FIG. 1 is a schematic cross-sectional front vieW
shoWing the overall con?guration of an image forming appa
ratus 100 according to this embodiment.
[0077] The image forming apparatus 100 shoWn in FIG. 1 is
a color image forming apparatus that forms an image using at
least one color (a plurality of colors or a single color) on a
sheet such as a recording paper (hereinafter, referred to as a
re?ective mirrors. The light exposure unit 1 is provided With
a polygon mirror scanned by a laser beam, and optical ele
ments such as lenses and mirrors for guiding the laser beam
re?ected by the polygon mirror to the photosensitive drums 3.
Furthermore, for the light exposure unit 1, other concepts can
be used, such as a concept employing a Writing head in Which
light-emitting elements such as EL (electroluminescence)
elements or LEDs (light-emitting diodes) are arranged in an
array.
[0085] The light exposure unit 1 irradiates the photosensi
tive drums 3 that are charged according to input image data,
thereby forming electrostatic latent images according to the
image data on the respective surfaces of the photosensitive
“recording paper”) according to image data transmitted from
drums 3.
the outside.
[0086] The toner cartridge units 21 are units containing
toner, and are con?gured such that the toner is supplied to
development baths of the development units 2. In the appa
[0078] The image forming apparatus 100 includes a docu
ment reading device 108 and an apparatus main body 110.
The apparatus main body 110 is provided With an image
forming portion 102 and a paper transport system 103.
[0079] The image forming portion 102 includes a light
exposure unit 1, a plurality of development units 2, a plurality
of photosensitive body units 4, an intermediate transfer belt
unit 6, a pre-transfer charging unit 8, a plurality of toner
cartridge units 21, and a ?xing unit 7. In this embodiment, the
light exposure unit 1, the development units 2, the photosen
sitive body units 4, the intermediate transfer belt unit 6, and
the toner cartridge units 21 function as a plurality of freely
detachable image forming units 200 that perform different
image forming operations. Here, it is assumed that the pho
ratus main body 110 of the image forming apparatus 100, the
toner supplied from the toner cartridge units 21 to the devel
opment baths of the development units 2 is controlled such
that the toner concentration of a developer in the development
baths is constant.
[0087] The development units 2 make the electrostatic
latent images formed on the respective photo sensitive drums
3 visible With toner of the four colors (Y, M, C, and K).
Furthermore, the photosensitive body units 4 further have a
cleaning function of removing and recovering toner that has
remained on the surfaces of the photosensitive drums 3 after
development and image transfer.
tosensitive body units 4 are units each formed by combining
[0088]
a unit for photosensitive operations, a unit for charging, and a
unit for cleaning into one unit.
the photosensitive drums 3 includes an intermediate transfer
[0080]
drive roller 62, an idler roller 63, a plurality of intermediate
transfer rollers 64, and a cleaning unit 65.
[0089] Four intermediate transfer rollers 64 are provided
Furthermore, the paper transport system 103
includes a paper feed tray 81, a manual paper feed tray 82, and
a paper discharge tray 91.
[0081]
A document placement platen 92 made of transpar
ent glass on Which a sheet such as a document (hereinafter,
referred to as a “document”) is to be placed is provided above
the apparatus main body 110, and an optical unit 90 for
reading a document is provided beloW the document place
ment platen 92. Furthermore, the document reading device
108 is provided above the document placement platen 92.
[0082] Image data processed in the image forming appara
tus 100 corresponds to a color image using a plurality of
colors (colors consisting of black (K), cyan (C), magenta (M),
and yelloW (Y), in this example). Accordingly, for each unit
group of the development units 2, the photosensitive body
units 4 (including photosensitive bodies in the present inven
tion), and the toner cartridge units 21, a plurality of units (four
units, respectively corresponding to black, cyan, magenta,
The intermediate transfer belt unit 6 disposed above
belt 61 functioning as an intermediate transfer member, a
respectively corresponding to colors Y, M, C, and K. The
drive roller 62 supports the intermediate transfer belt 61 in a
tensioned state in cooperation With the idler roller 63 and the
intermediate transfer rollers 64. When the drive roller 62 is
driven to rotate, the intermediate transferbelt 61 is revolved in
the movement direction (direction indicated by arroW M in
FIG. 1), Which causes the idler roller 63 and the intermediate
transfer rollers 64 to be idly rotated.
[0090] The intermediate transfer rollers 64 are supplied
With a transfer bias for transferring toner images formed on
the photosensitive drums 3 to the intermediate transfer belt
61.
[0091] The intermediate transfer belt 61 is provided so as to
be in contact With each of the photosensitive drums 3. Toner
and yelloW, in this example) are provided in order to form a
images of the respective colors formed on the photosensitive
plurality of types (four types in this example) of images
drums 3 are sequentially transferred to the intermediate trans
fer belt 61 so as to be superimposed one after another, so that
a color toner image (multicolor toner image) can be formed
on the surface of the intermediate transfer belt 61. The inter
corresponding to the respective colors, and these units form
image stations for the respective colors (four colors, in this
example).
Feb. 14, 2013
US 2013/0039680 A1
mediate transfer belt 61 is, for example, formed in the form of
an endless belt made of a ?lm having a thickness of approxi
mately 100 um to 150 pm.
[0092]
Toner images are transferred from the photosensi
tive drums 3 to the intermediate transfer belt 61 by means of
the intermediate transfer rollers 64 that are in contact With the
back face of the intermediate transfer belt 61. The intermedi
ate transfer rollers 64 are supplied With a high voltage transfer
bias (high voltage having a polarity (+) opposite the polarity
(—) of the charged toner) for transferring toner images. The
intermediate transfer rollers 64 are each made by forming its
core With a metal (e. g., stainless steel) shaft having a diameter
of 8 mm to 10 mm and covering the surface of the core With
a conductive elastic material (e.g., EPDM (ethylene propy
lene diene rubber) or resin material such as foamed urethane).
The intermediate transfer rollers 64 function as transfer elec
trodes that apply a high voltage uniformly to the intermediate
transferbelt 61 With the conductive elastic material.Although
roller-like transfer electrodes are used as the transfer elec
trodes in this embodiment, other transfer electrodes such as
brush-like transfer electrodes can be used.
[0093] As described above, toner images that are made
visible according to the color phases on the respective pho
tosensitive drums 3 are superimposed on the intermediate
transfer belt 61. When the intermediate transfer belt 61 is
revolved, the toner images superimposed on the intermediate
transfer belt 61 are transferred to a recording paper by a
transfer roller 10 that forms a second transfer mechanism
portion disposed in a contact position Where the recording
fer belt 61 and on the doWnstream side of the photosensitive
body units 4 in the movement direction M of the intermediate
transfer belt 61.
[0097] Incidentally, the toner images that are transferred
from the photosensitive drums 3 to the intermediate transfer
belt 61 include halftone areas or solid areas, or include areas
having different numbers of toner layers, and, therefore, the
charge level may vary from area to area. Furthermore, the
charge level Within a toner image on the intermediate transfer
belt 61 after the primary transfer may vary due to exfoliation
discharges generated in a gap on the doWnstream side adja
cent to the primary transfer portion in the movement direction
M of the intermediate transfer belt 61. Such variations in the
charge level in the same toner image decrease the transfer
margin When transferring a toner image on the intermediate
transfer belt 61 to a sheet.
[0098]
Therefore, the pre-transfer charging unit 8 is used to
uniformly charge a toner image before transfer to a sheet, so
that the variations in the charge level in the same toner image
are cancelled, Which makes it possible to improve the transfer
margin in the secondary transfer.
[0099] Furthermore, the apparatus main body 110 is pro
vided With a paper transport path S such that a recording paper
from the paper feed tray 81 and the manual paper feed tray 82
is transported via the transfer roller 10 and the ?xing unit 7 to
the paper discharge tray 91. Arranged in the vicinity of the
paper transport path S are pickup rollers 11a and 11b, a
plurality of transport rollers 12a to 12d, registration rollers
13, the transfer roller 10, and a heat roller 71 and a pressure
paper is in contact With the intermediate transfer belt 61. Note
that, as the con?guration of the second transfer mechanism
portion, not only transfer rollers but also other transfer con
roller 72 in the ?xing unit 7.
[0100] The registration rollers 13 temporarily hold a
recording paper that is being transported on the paper trans
?gurations such as those employing corona chargers or trans
fer belts can be used.
recording paper to the transfer roller 10 at a timing Where the
[0094]
At this time, the transfer roller 10 is supplied With a
voltage (high voltage having a polarity (+) opposite the polar
ity (—) of the charged toner) for transferring toner to the
recording paper in a state Where a transfer nip is formed
betWeen the transfer roller 10 and the intermediate transfer
belt 61. The transfer nip is formed betWeen the transfer roller
10 and the intermediate transfer belt 61 by the transfer roller
10 and the drive roller 62 pressing against each other. In order
to maintain the transfer nip steadily, either one of the transfer
roller 10 and the drive roller 62 is a hard roller made of a hard
material (e.g., metal), and the other is an elastic roller made of
a soft material (e.g., elastic rubber or resin material such as
foamed resin).
[0095]
When transferring a toner image from the interme
diate transfer belt 61 to a recording paper With the transfer
roller 10, toner may remain on the intermediate transfer belt
61 Without being transferred to the recording paper. The toner
that has remained on the intermediate transfer belt 61 Will
cause mixture of toner colors in subsequent processes. There
fore, the toner that has remained on the intermediate transfer
belt 61 is removed and recovered by the cleaning unit 65.
Speci?cally, the cleaning unit 65 includes a cleaning member
(e. g., a cleaning blade) that is in contact With the intermediate
transfer belt 61. The idler roller 63 supports the intermediate
transfer belt 61 from the inside (back face side), and the
cleaning member is in contact With the intermediate transfer
belt 61 so as to press the intermediate transfer belt 61 toWard
the idler roller 63 from the outside.
[0096]
The pre-transfer charging unit 8 in this example has
a pre-transfer charger (PTC), and is provided near the inter
mediate transfer belt 61 on the upstream side of the transfer
nip betWeen the transfer roller 10 and the intermediate trans
port path S. Then, the registration rollers 13 transport the
leading edge of the toner image on the photosensitive drums
3 is aligned With the leading edge of the recording paper.
[0101] The ?xing unit 7 ?xes an un?xed toner image onto
the recording paper, and includes the heat roller 71 and the
pressure roller 72 that function as ?xing rollers. The heat
roller 71 is heated With a heater 71a provided inside it, and is
kept at a predetermined ?xing temperature based on a signal
from a temperature detector 71b. The ?xing unit 7 is further
provided With an external heating belt 73 for heating the heat
roller 71 from the outside.
[0102] In the thus con?gured image forming apparatus 100,
When there is a request for simplex printing on a recording
paper, a recording paper fed from the paper feed tray 81 or the
manual paper feed tray 82 is transported to the registration
rollers 13 With the transport rollers 12a arranged along the
paper transport path S, and is transported by the transfer roller
10 at a timing Where the leading edge of the recording paper
is aligned With the leading edge of the toner image on the
intermediate transfer belt 61, and then the toner image is
transferred to the recording paper. Subsequently, the record
ing paper passes through the ?xing unit 7, so that un?xed
toner on the recording paper is melted by heat and adheres to
the recording paper, and then the recording paper is dis
charged to the paper discharge tray 91 through the transport
rollers 12b.
[0103] When there is a request for duplex printing on a
recording paper, in a state Where the simplex printing as
described above is completed and the trailing edge of the
recording paper that has passed through the ?xing unit 7 is
positioned betWeen the last transport rollers 12b and a
branching portion Sa on the paper transport path S, the trans
port rollers 12b are rotated in reverse, and, therefore, the
recording paper is guided to the transport rollers 12c and 12d.
Feb. 14, 2013
US 2013/0039680 A1
transfer nip through the registration rollers 13 undergoes
scanning and irradiating the imaging device, and, if color
misalignment has occurred, the optical path length in the LSU
printing on its back face, and then is discharged onto the paper
is corrected.
discharge tray 91.
[0104] The thus con?gured image forming apparatus 100
ment using the adjustment means Will be described in more
Then, the recording paper that has been transported to the
according to this embodiment includes essential constituent
components shoWn in FIG. 2. Speci?cally, the image forming
[0108] Hereinafter, the adjustment of positional misalign
detail. First, the detection patterns P1, P2, P3, and P4 respec
tively corresponding to the four respective colors, Which
apparatus 1 00 is provided With a main control portion 3 00 that
function as references, are set. It is assumed that the detection
controls various operations of the image forming apparatus
patterns P1, P2, P3, and P4 are arranged at constant intervals.
1 00, an input portion 3 01 on Which a user directly performs an
Furthermore, four detection patterns P1, P2, P3, and P4 form
input operation, a display portion 302 that displays informa
one detection pattern block (symbol PB shoWn in FIGS. 3 and
4), and such a detection pattern block PB is repeatedly formed
a plurality of times in the sub-scanning direction of the sensor
portions 310 (imaging devices) (hereinafter, referred to as a
tion such as an image, a storage portion 303 that stores image
data and the like, an image processing operation portion 304
that performs an image processing operation, a netWork inter
face 306 (network I/F) that is connected to the outside via a
netWork 305, the optical unit 90 that scans a document, the
image forming portion 102 that forms an image of a document
on a recording paper, and a facsimile portion 308 that is
connected to the outside (that transmits a FAX) via a tele
phone line 307. These constituent components are connected
to each other via a bus 309 such that image data (signals) can
be transmitted and received.
[0105]
The main control portion 300 controls the input
portion 301, the display portion 302, the storage portion 303,
the image processing operation portion 304, the netWork
interface 306, the optical unit 90, the image forming portion
102, and the facsimile portion 308. For example, the main
control portion 300 causes the image forming portion 102 to
perform a printing process (image forming process) based on
image data received via the netWork interface 306. Further
more, the main control portion 300 causes the facsimile por
tion 308 to perform a facsimile transmitting process that dials
a designated destination phone number and transmits image
data that is a transmission target. Furthermore, the main con
trol portion 300 causes the optical unit 90 to perform a scan
ning process that reads an image formed on a document. In
this manner, the main control portion 300 causes these con
stituent components of the image forming apparatus 100 to
perform various operations based on input from the input
portion 301, input from the outside via the netWork interface
306, input from the outside via the facsimile portion 308, and
the like.
[0106] The image forming portion 102 is a so-called imag
ing engine that is controlled by the main control portion 300,
and refers to a group consisting of a device that forms (out
puts) an image on a recording paper at an image formation
position based on document image data, printing image data,
and the like, and a constituent component such as an MPU
that controls the device.
[0107] Incidentally, the image forming apparatus 100
according to this embodiment is provided With an adjustment
means for adjusting positional misalignment in order to cor
rect color misalignment of an image. The adjustment means
includes sensor portions 310 that are provided in the image
forming portion 102 (see FIGS. 3 and 4). The main control
portion 300 controls the image forming portion 102 to per
“sub-scanning direction”), thereby forming a plurality of
detection pattern blocks PB. The storage portion 303 stores
data of detection images of four detection patterns P1, P2, P3,
and P4 and a plurality of detectionpattem blocks PB that have
been formed in this manner and intervals betWeen the detec
tion patterns P1, P2, P3, and P4 (hereinafter, referred to as
“reference intervals”) as data of reference detection images.
[0109] At the time of detection in the adjustment of color
misalignment, four image stations sequentially form the
detection patterns P1, P2, P3, and P4 (see FIGS. 3 and 4)
respectively corresponding to the four respective colors in the
sub-scanning direction on the intermediate transfer belt 61.
[0110]
The intervals betWeen the detection patterns P1, P2,
P3, and P4 formed on the intermediate transfer belt 61 are
detected by the sensor portions 310, the detected data and the
reference interval data are compared With each other to detect
color misalignment, and the optical path length is corrected
according to the color misalignment amount.
[0111] Regarding the adjustment of color misalignment
using the above-described adjustment means, in this embodi
ment, data of detection images having tWo different intervals
(see FIGS. 3 and 4) is stored in the storage portion 303 as
reference intervals. Speci?cally, data of detection images
having a reference interval of 6.3 mm as shoWn in FIG. 3
(hereinafter, referred to as “?rst data D1”) and data of detec
tion images having a reference interval of 3.8 mm, Which is
smaller than that of the ?rst data D1, as shoWn in FIG. 4
(hereinafter, referred to as “second data D2”) are stored.
[0112] The ?rst data D1 of detection images is used as
reference interval data for rough adjustment of color mis
alignment. As shoWn in FIG. 3, the detection images are
respectively formed at portions corresponding to both sides in
the Width direction (upper and loWer sides in the draWing) on
the intermediate transfer belt 61, the detection patterns P1,
P2, P3, and P4 are formed as rectangles having the same siZe
and the same shape, and the longitudinal direction of the
patterns matches the main-scanning direction. According to
the ?rst data D1 of the detection images having an interval of
6.3 mm, three detection pattern blocks PB can be formed With
respect to one revolution of the photosensitive drums 3.
[0113] The second data D2 of detection images is used as
form adjustment of positional misalignment using the adjust
reference interval data for ?ne adjustment of color misalign
ment means, so that detection patterns respectively corre
ment. As shoWn in FIG. 4, the detection image are respec
sponding to the four respective colors (see P1, P2, P3, and P4
tively formed at portions corresponding to both sides in the
Width direction (upper and loWer sides in the draWing) on the
shoWn in FIGS. 3 and 4) are formed on the intermediate
transfer belt 61, the sensor portions 310 are used to detect
intermediate transfer belt 61, the detection patterns P1, P2,
Whether or not there is positional misalignment betWeen the
P3, and P4 are formed as rectangles having the same siZe and
detection patterns P1, P2, P3, and P4, and, if there is posi
tional misalignment, the optical path length in the LSU is
the same shape, and the longitudinal direction of the patterns
matches the main-scanning direction. According to the sec
ond data D2 of the detection images having an interval of 3.8
corrected. As the sensor portions 310 in this example, an
imaging device such as a CCD is used. The detection patterns
formed on the intermediate transfer belt 61 are detected by
mm, ?ve detection pattern blocks PB can be formed With
respect to one revolution of the photosensitive drums 3.
Feb. 14, 2013
US 2013/0039680 A1
[0114] The ?rst data D1 and the second data D2 are differ
ent from each other only in terms of the interval in the sub
scanning direction, and are the same in terms of the Width (the
length in the sub-scanning direction), the length (the length in
[0124]
The data actually detected in Step S12 and the sec
ond data D2 are compared With each other to detect color
misalignment (Step S13).
the main-scanning direction), and the color arrangement
order of the detection patterns of the respective colors. Thus,
[0125] lfthere is color misalignment in Step S13 (YES in
Step S13), the optical path length is corrected according to the
color misalignment amount (Step S14, Which corresponds to
the amount of toner consumed in ?ne adjustment using the
second data D2 is only 5/3 of the amount of toner consumed
the adjustment step in the present invention), and the ?ne
in rough adjustment using the ?rst data D1. Accordingly, it is
possible to improve the detection precision While suppressing
the amount of toner consumed in correction of color mis
adjustment of color misalignment ends, thereby ending the
adjustment of color misalignment.
[0126]
Furthermore, if there is no color misalignment in
alignment.
Step S13 (NO in Step S13), the ?ne adjustment of color
misalignment ends, thereby ending the adjustment of color
[0115] Next, the color misalignment adjusting method
misalignment.
using the above-described adjustment means (the ?rst data
D1 and the second data D2) Will be described in detail With
settings of the image forming apparatus 100, for example,
reference to FIG. 5.
[0127]
Furthermore, if there is no request to perform initial
If there is a request to perform initial settings of the
When performing inspection in the plant or When installing
the image forming apparatus 100 (NO in Step S1), the ordi
image forming apparatus 100, for example, When performing
inspection in the plant, When installing the image forming
nary image forming operation (image forming process) is
performed (Step S7), and the image forming operation (image
apparatus 100, or When performing correction of color mis
forming process) is performed based on a preset condition
(Step S8). The preset condition in this example may be a
condition relating to the image forming process or may be a
[0116]
alignment as designated by the user (manual operation), these
occasions being conditions preset by the user (YES in Step
S1), the ?rst data D1 (the patterns for rough adjustment) is
read from the storage portion 303 (Step S2).
[0117] After the ?rst data D1 is read in Step S2, the image
forming portion 102 uses the photosensitive body units 4
corresponding to the four respective colors to form the detec
tion patterns P1, P2, P3, and P4 on the intermediate transfer
belt 61 based on the ?rst data D1 and its related data (refer
ence interval, etc.) (Step S3, Which corresponds to the forma
tion step in the present invention).
[0118] After the detection patterns P1, P2, P3, and P4 are
formed on the intermediate transfer belt 61 as shoWn in FIG.
3 in Step S3, actual intervals betWeen adjacent detection
patterns P1, P2, P3, and P4 are detected by the sensor portions
condition relating to the image forming time. Speci?cally, the
preset condition may be the number of recording papers that
have undergone image formation or may be the time at Which
image formation Was performed.
[0128] If the preset condition is not satis?ed in Step S8 (NO
in Step S9), the image forming operation (image forming
process) is continuously performed (Step S8).
[0129]
Furthermore, if the preset condition is satis?ed in
Step S8 (YES in Step S9), the main control portion 300
automatically (periodically) or forcibly performs ?ne adjust
ment of color misalignment (YES in Step S9), and the second
data D2 (the patterns for ?ne adjustment) is read from the
storage portion 303 (Step S10).
310 (Step S4).
[0130]
[0119]
image forming portion 102 uses the photosensitive body units
The data actually detected in Step S4 and the ?rst
data D1 are compared With each other to detect color mis
alignment (Step S5).
[0120] If there is color misalignment in Step S5 (YES in
Step S5), the optical path length is corrected according to the
color misalignment amount (Step S6, Which corresponds to
the adjustment step in the present invention), and the rough
adjustment of color misalignment ends. Next, in order to
perform ?ne adjustment using the second data D2, the second
data D2 (the patterns for ?ne adjustment) is read from the
storage portion 303 (Step S10).
[0121]
Furthermore, if there is no color misalignment in
Step S5 (NO in Step S5), the rough adjustment of color
misalignment ends. Next, in order to perform ?ne adjustment
using the second data D2 (the patterns for ?ne adjustment),
After the second data D2 is read in Step S10, the
4 corresponding to the four respective colors to form the
detection patterns P1, P2, P3, and P4 on the intermediate
transfer belt 61 based on the second data D2 and its related
data (reference interval, etc.) (Step S11, Which corresponds to
the formation step in the present invention).
[0131] After the detection patterns P1, P2, P3, and P4 are
formed on the intermediate transferbelt 61 in Step S11, actual
intervals betWeen adjacent detection patterns P1, P2, P3, and
P4 are detected by the sensor portions 310 (Step S12).
[0132] The data actually detected in Step S12 and the sec
ond data D2 are compared With each other to detect color
misalignment (Step S13).
the second data D2 is read from the storage portion 303 (Step
[0133] lfthere is color misalignment in Step S13 (YES in
Step S13), the optical path length is corrected according to the
color misalignment amount (Step S14, Which corresponds to
S10).
the adjustment step in the present invention), and the ?ne
[0122]
After the second data D2 is read in Step S10, the
image forming portion 102 uses the photosensitive body units
4 corresponding to the four respective colors to form the
detection patterns P1, P2, P3, and P4 on the intermediate
adjustment of color misalignment ends, thereby ending the
adjustment of color misalignment.
[0134]
Furthermore, if there is no color misalignment in
transfer belt 61 based on the second data D2 and its related
Step S13 (NO in Step S13), the ?ne adjustment of color
misalignment ends, thereby ending the adjustment of color
data (reference interval, etc.) (Step S11, Which corresponds to
misalignment.
the formation step in the present invention).
[0123] After the detection patterns P1, P2, P3, and P4 are
apparatus 100 according to this embodiment or the color
formed on the intermediate transferbelt 61 in Step S11, actual
misalignment adjusting method using the image forming
intervals betWeen adjacent detection patterns P1, P2, P3, and
apparatus 100, since the ?rst data D1 and the second data D2
having different intervals are used to perform adjustment of
P4 are detected by the sensor portions 310 (Step S12).
[0135]
In this manner, according to the image forming
Feb. 14, 2013
US 2013/0039680 A1
example is applicable also to other image forming appara
color misalignment, tWo adjustment choices can be provided
for the adjustment of color misalignment. As a result, the
adjustment of color misalignment can be performed With a
given level of precision depending on occasions such as those
When performing initial settings or When performing mainte
tuses such as copiers, printers, and facsimile machines.
[0141] The present invention may be embodied in various
other forms Without departing from the spirit, gist, or essen
tial characteristics thereof. The embodiments disclosed in this
nance after use of the image forming apparatus 100. That is to
say, the detection can be performed With an optimal level of
and not limiting. The scope of the invention is indicated by the
precision depending on the conditions. Furthermore, the
amount of toner consumed can be suppressed Whichever type
of data of detection images is used to perform adjustment of
color misalignment. In this embodiment, since the ?rst data
D1 and the second data D2 are used, the adjustment of color
misalignment can be sequentially performed from rough
adjustment to ?ne adjustment. In this case, the correction of
color misalignment can be precisely performed.
[0136] Furthermore, since the main control portion 300
performs rough adjustment of color misalignment based on
the ?rst data D1 having an interval larger than that of the
second data D2, and then performs ?ne adjustment of color
misalignment based on the second data D2 having an interval
smaller than that of the ?rst data D1, the correction of color
misalignment can be precisely performed.
[0137] Furthermore, since the ?rst data D1 and the second
data D2 are used to perform adjustment of color misalign
ment based on the preset conditions, rough adjustment of
color misalignment using the ?rst data D1 can be performed
based on a preset condition (e.g., at the time of initial settings)
Where the color misalignment amount may be signi?cant, and
?ne adjustment of color misalignment using the second data
D2 can be periodically performed based on a preset condition
in ordinary use (e.g., the time). As a result, since the rough
adjustment of color misalignment using the ?rst data D1 has
been performed in advance, misalignment in the ?ne adjust
ment of color misalignment using the second data D2 is
slight, and the adjustment of color misalignment can be more
precisely performed. On the other hand, if the adjustment of
color misalignment using the second data D2 is performed
under, for example, the conditions at the time of initial set
tings, since the range in Which the adjustment of color mis
alignment can be performed is narroW, misalignment betWeen
installation positions When installing the image forming por
tion 102 such as the plurality of photosensitive body units 4
has to be substantially eliminated. Thus, With the technique at
the time of the present application, it is dif?cult to perform
adjustment of color misalignment using the second data D2
When the color misalignment amount may be signi?cant, for
example, at the time of initial settings.
[0138] In this embodiment, although the adjustment of
color misalignment is performed With respect to four colors,
the number of colors is not limited to this. For example, any
number is possible as long as it is a plural.
[0139]
Furthermore, in this embodiment, although the ?rst
data D1 and the second data D2 are used to perform adjust
ment of color misalignment, the number of data types of
detection images is not limited to this. For example, three or
more data types of detection images may be used. In this case,
the adjustment of color misalignment can be performed in a
stepWise manner from rough adjustment to ?ne adjustment,
and, therefore, the correction of color misalignment can be
more precisely performed.
[0140] Note that the color image forming apparatus accord
ing to the present invention shoWing this embodiment as an
application are to be considered in all respects as illustrative
appended claims rather than by the foregoing description. All
variations and modi?cations falling Within the meaning and
range of equivalency of the appended claims are intended to
be embraced therein.
[0142]
Furthermore, the present invention is effective for
color image forming apparatuses.
What is claimed is:
1. A color image forming apparatus,
Wherein a plurality of detection patterns respectively cor
responding to a plurality of colors are formed from a
plurality of photosensitive body units respectively cor
responding to the plurality of colors onto a transfer
member in a sub-scanning direction of the transfer mem
ber, intervals betWeen detection patterns adjacent to
each other in the sub-scanning direction among the plu
rality of formed detection patterns are detected, and
adj ustment of color misalignment is performed based on
the detected intervals,
the plurality of detection patterns have the same siZe and
the same shape, and
the adjustment of color misalignment is performed using at
least tWo types of data of detection images having dif
ferent intervals as data of detection images including the
plurality of detection patterns.
2. The color image forming apparatus according to claim 1,
Wherein the data of detection images includes tWo types of
data composed of ?rst data of detection images and
second data of detection images having an interval
smaller than that of the ?rst data, and
after the adjustment of color misalignment using the ?rst
data is performed, the adjustment of color misalignment
using the second data is performed.
3. The color image forming apparatus according to claim 2,
Wherein the adjustment of color misalignment is performed
based on a preset condition using the ?rst data and the second
data.
4. A color misalignment adjusting method of a color image
forming apparatus, comprising:
a formation step of forming a plurality of detection patterns
respectively corresponding to a plurality of colors from
a plurality of photosensitive body units respectively cor
responding to the plurality of colors onto a transfer
member in a sub-scanning direction of the transfer mem
ber; and
an adjustment step of detecting intervals betWeen detection
patterns adjacent to each other in the sub-scanning direc
tion among the plurality of detection patterns formed in
the formation step, and performing adjustment of color
misalignment based on the detected intervals;
Wherein the plurality of detection patterns have the same
siZe and the same shape, and
the adjustment of color misalignment is performed in the
adjustment step using at least tWo types of data of detec
tion images having different intervals as data of detec
tion images including the plurality of detection patterns.
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