U.S. patent number RE45,063 [Application Number 13/559,550] was granted by the patent office on 2014-08-05 for apparatus and method for controlling recording and sheet conveying based on recording scans and sheet position.
This patent grant is currently assigned to Canon Kabushiki Kaisha. The grantee listed for this patent is Tetsuya Ishikawa, Kentaro Onuma, Minoru Teshigawara, Haruyuki Yanagi. Invention is credited to Tetsuya Ishikawa, Kentaro Onuma, Minoru Teshigawara, Haruyuki Yanagi.
United States Patent |
RE45,063 |
Onuma , et al. |
August 5, 2014 |
Apparatus and method for controlling recording and sheet conveying
based on recording scans and sheet position
Abstract
A recording apparatus for forming images using a recording head
includes a feeding roller, a conveying roller, a conveyance control
unit, and a recording control unit. The conveyance control unit
performs a conveying operation a number of times after the trailing
end of a sheet reaches a predetermined position defined between the
feeding roller and the conveying roller such that the trailing end
of the sheet is disposed in a predetermined range upstream of the
conveying roller in a sheet conveying direction after the conveying
operations. At least one of the conveying operations performed a
number of times is performed based on a distance from the position
of the trailing end of the sheet to the position of the conveying
roller.
Inventors: |
Onuma; Kentaro (Yokohama,
JP), Yanagi; Haruyuki (Machida, JP),
Ishikawa; Tetsuya (Yokohama, JP), Teshigawara;
Minoru (Yokohama, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Onuma; Kentaro
Yanagi; Haruyuki
Ishikawa; Tetsuya
Teshigawara; Minoru |
Yokohama
Machida
Yokohama
Yokohama |
N/A
N/A
N/A
N/A |
JP
JP
JP
JP |
|
|
Assignee: |
Canon Kabushiki Kaisha (Tokyo,
JP)
|
Family
ID: |
39113109 |
Appl.
No.: |
13/559,550 |
Filed: |
July 26, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
11837377 |
Aug 10, 2007 |
7764389 |
Jul 27, 2010 |
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Foreign Application Priority Data
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Aug 23, 2006 [JP] |
|
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2006-226701 |
|
Current U.S.
Class: |
358/1.12; 347/16;
347/104 |
Current CPC
Class: |
B41J
13/0027 (20130101); H04N 1/1215 (20130101); B41J
11/0095 (20130101); H04N 1/0062 (20130101); H04N
1/128 (20130101); H04N 2201/0082 (20130101); H04N
1/1912 (20130101) |
Current International
Class: |
G06K
15/16 (20060101); B41J 13/03 (20060101) |
Field of
Search: |
;358/1.12,502,504,406,488,498,296 ;347/12,14,16,101,104 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Rogers; Scott A
Attorney, Agent or Firm: Canon U.S.A., Inc. IP Division
Claims
What is claimed is:
.[.1. A recording apparatus for forming images using a recording
head scanning over a predetermined area on a sheet N times, the
recording apparatus comprising: a feeding roller configured to
convey the sheet disposed on a stacking unit; a conveying roller
configured to further convey the sheet fed by the feeding roller; a
conveyance control unit configured to control drive of the
conveying roller each time scanning is performed by the recording
head; and a recording control unit configured to control a first
recording in which the scanning is performed N times by selecting
recording elements of the recording head until a trailing end of
the sheet reaches a predetermined position defined between the
feeding roller and the conveying roller, and configured to control
a second recording in which the scanning is performed N times using
a part of the recording elements of the recording head after the
trailing end of the sheet reaches the predetermined position,
wherein the conveyance control unit performs a conveying operation
a number of times based on the value of N after the trailing end of
the sheet reaches the predetermined position such that the trailing
end of the sheet is disposed in a first range remote from and
upstream of the conveying roller in a direction in which the sheet
is conveyed after the conveying operations, and wherein at least
one of the conveying operations performed a number of times based
on the value of N is performed based on a distance from a position
of the trailing end of the sheet to the position of the conveying
roller..].
.[.2. The recording apparatus according to claim 1, further
comprising a detection unit disposed between the feeding roller and
the conveying roller on a conveying path and configured to detect
the trailing end of the sheet..].
.[.3. The recording apparatus according to claim 1, wherein the
trailing end of the sheet is conveyed to a second range downstream
of the conveying roller in the direction in which the sheet is
conveyed by a conveying operation performed after the trailing end
of the sheet is disposed in the first range..].
.[.4. A method for controlling a recording apparatus for forming
images using a recording head scanning over a predetermined area on
a sheet N times, the recording apparatus including a feeding roller
configured to convey the sheet disposed on a stacking unit and a
conveying roller configured to further convey the sheet fed by the
feeding roller, the method comprising: controlling drive of the
conveying roller each time scanning is performed by the recording
head; and controlling a first recording in which the scanning is
performed N times by selecting recording elements of the recording
head until a trailing end of the sheet reaches a predetermined
position defined between the feeding roller and the conveying
roller, and controlling a second recording in which the scanning is
performed N times using a part of the recording elements of the
recording head after the trailing end of the sheet reaches the
predetermined position, wherein the drive of the conveying roller
is controlled so as to perform a conveying operation a number of
times based on the value of N after the trailing end of the sheet
reaches the predetermined position such that the trailing end of
the sheet is disposed in a first range including the position of
the conveying roller and upstream of the conveying roller in a
direction in which the sheet is conveyed after the conveying
operations, and wherein at least one of the conveying operations
performed a number of times based on the value of N is performed
based on a distance from a position of the trailing end of the
sheet to the position of the conveying roller..].
.Iadd.5. A recording apparatus comprising: a recording head
configured to record an image on a sheet; a conveying roller,
disposed upstream of the recording head in a conveying direction,
configured to convey the sheet; a pinch roller configured to pinch
the sheet, together with the conveying roller, at a nip portion; a
driving unit configured to drive the conveying roller by a first
conveying amount, and by a second conveying amount when the
trailing end of the sheet passes through the nip portion; and an
adjustment conveying unit configured to convey the sheet by an
adjustment conveying amount, based on information on a position of
a trailing end of the sheet such that the trailing end of the sheet
stops in a predetermined area located upstream of the nip
portion..Iaddend.
.Iadd.6. The recording apparatus according to claim 5, wherein the
adjustment conveying amount is larger than the first conveying
amount..Iaddend.
.Iadd.7. The recording apparatus according to claim 5, wherein the
driving unit conveys the sheet whose trailing end is in the
predetermined area by the second conveying amount..Iaddend.
.Iadd.8. The recording apparatus according to claim 7, wherein the
second conveying amount is larger than the first conveying
amount..Iaddend.
.Iadd.9. The recording apparatus according to claim 7, wherein the
driving unit drives the conveying roller such that the trailing end
of the sheet does not stop in an unstable stop area including the
nip portion..Iaddend.
.Iadd.10. The recording apparatus according to claim 5, further
comprising: a detection unit disposed upstream of the conveying
roller in the conveying direction and configured to detect the
trailing end of the sheet..Iaddend.
.Iadd.11. The recording apparatus according to claim 10, wherein
the adjustment conveying unit determines the adjustment conveying
amount based on the information on the position of the trailing end
of the sheet detected by the detection unit..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to recording apparatuses (e.g.,
ink-jet recording apparatuses) for recording (e.g., forming images)
using recording heads, and relates to methods for controlling the
apparatuses.
2. Description of the Related Art
Mechanisms such as ink-jet recording apparatuses that convey sheets
usually include line feed (LF) rollers (conveying rollers) and
eject rollers. When the mechanisms convey sheets, the LF rollers
are used as main conveying units and the eject rollers are used as
auxiliary conveying units.
The LF rollers are disposed upstream in a direction in which sheets
are conveyed (conveying direction), and the eject rollers are
disposed downstream in the conveying direction. Recording heads
scan over areas between the LF rollers and the eject rollers.
Therefore, areas corresponding to areas scanned by the recording
heads while the sheets are engaged by the LF rollers and the eject
rollers are referred to as "recording areas".
Furthermore, areas corresponding to areas scanned by the recording
heads while the sheets are engaged by only the eject rollers are
also referred to as "recording areas". That is, a recording is also
made in areas adjacent to the trailing ends of the sheets.
In order to make up for a reduction in conveying accuracy during
recording of the trailing ends of the sheets, a technology
described in Japanese Patent Laid-Open No. 2004-230817 reduces the
number of nozzles of a recording head to be used and the conveying
amount of a sheet per scan when a recording is made in areas
adjacent to the trailing ends of the sheet.
FIG. 9 illustrates the positional relationship among a conveying
roller 136, a pinch roller 137, and the trailing end of a sheet. In
FIG. 9, the sheet is fed from right to left. Each arrow indicates a
conveying operation. The end points of the arrows indicate the
positions of the trailing end of the sheet after the conveying
operations, and the start points of the arrows indicate the
positions of the trailing end of the sheet before the conveying
operations. An area between A and B shown in FIG. 9 is referred to
as an "unstable stop area" where the position of the trailing end
of a sheet that has stopped in this area is not stabilized. FIG. 9
illustrates two types of conveying sequences. In Sequence (1), the
sheet is conveyed by a conveying amount of P/8 in areas other than
the unstable stop area. Furthermore, in Sequence (1), the sheet is
conveyed by a conveying amount of 3P/8 such that the trailing end
of the sheet does not stop in the unstable stop area. In Sequence
(2), the sheet is conveyed by a conveying amount of P/8 in all
areas. In this case, the trailing end of the sheet stops in the
unstable stop area two times.
In Sequence (1), the conveying amount per conveying operation is
small. This leads to increases in the number of times scanning is
performed by the recording head and in the number of conveying
operations, resulting in a reduction in throughput in recording
operations.
In Sequence (2), the trailing end of the sheet stops in the
unstable stop area two times. Therefore, the conveying amount in
the unstable stop area becomes different from that in areas other
than the unstable stop area, resulting in a reduction in image
quality.
SUMMARY OF THE INVENTION
An embodiment of the present invention is directed to a recording
apparatus capable of stopping the trailing end of a sheet in a
predetermined range when the trailing end of the sheet passes
through a conveying roller during recording.
According to an aspect of the present invention, an embodiment is
directed to a recording apparatus for forming images using a
recording head scanning over a predetermined area on a sheet N
times. The recording apparatus includes a feeding roller configured
to convey the sheet disposed on a stacking unit; a conveying roller
configured to further convey the sheet fed by the feeding roller; a
conveyance control unit configured to control drive of the
conveying roller each time scanning is performed by the recording
head; and a recording control unit configured to control a first
recording in which the scanning is performed N times by selecting
recording elements of the recording head until a trailing end of
the sheet reaches a predetermined position defined between the
feeding roller and the conveying roller, and configured to control
a second recording in which the scanning is performed N times using
a part of the recording elements of the recording head after the
trailing end of the sheet reaches the predetermined position. The
conveyance control unit performs a conveying operation a number of
times based on the value of N after the trailing end of the sheet
reaches the predetermined position such that the trailing end of
the sheet is disposed in a first range remote from and upstream of
the conveying roller in a direction in which the sheet is conveyed
after the conveying operations. At least one of the conveying
operations performed a number of times based on the value of N is
performed based on a distance from a position of the trailing end
of the sheet to the position of the conveying roller.
According to another aspect of the present invention, an embodiment
is directed to a method for controlling a recording apparatus for
forming images using a recording head scanning over a predetermined
area on a sheet N times. The recording apparatus includes a feeding
roller configured to convey the sheet disposed on a stacking unit
and a conveying roller configured to further convey the sheet fed
by the feeding roller. The method includes controlling drive of the
conveying roller each time scanning is performed by the recording
head; and controlling a first recording in which the scanning is
performed N times by selecting recording elements of the recording
head until a trailing end of the sheet reaches a predetermined
position defined between the feeding roller and the conveying
roller, and controlling a second recording in which the scanning is
performed N times using a part of the recording elements of the
recording head after the trailing end of the sheet reaches the
predetermined position. The drive of the conveying roller is
controlled so as to perform a conveying operation a number of times
based on the value of N after the trailing end of the sheet reaches
the predetermined position such that the trailing end of the sheet
is disposed in a first range including the position of the
conveying roller and upstream of the conveying roller in a
direction in which the sheet is conveyed after the conveying
operations. At least one of the conveying operations performed a
number of times based on the value of N is performed based on a
distance from a position of the trailing end of the sheet to the
position of the conveying roller.
Further features of the present invention will become apparent from
the following description of exemplary embodiments with reference
to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a recording apparatus according to
an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the recording apparatus
according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view of conveying mechanisms of the
recording apparatus according to an embodiment of the present
invention.
FIG. 4 illustrates a sequence of conveyance control according to an
embodiment of the present invention.
FIG. 5 is a control flow of a recording operation according to an
embodiment of the present invention.
FIG. 6 is a control flow of a conveying operation according to an
embodiment of the present invention.
FIG. 7 illustrates areas of nozzles of a recording head used for
recording and conveying amounts of a sheet according to an
embodiment of the present invention.
FIG. 8 illustrates the areas of nozzles of the recording head used
for recording and the conveying amounts of the sheet according to
an embodiment of the present invention.
FIG. 9 illustrates sequences of conveyance control according to a
known technology.
FIG. 10 is a control block diagram of the recording apparatus
according to an embodiment of the present invention.
FIG. 11 illustrates a state where a conveying operation is stopped
according to an embodiment of the present invention.
FIG. 12 illustrates another sequence of the conveyance control
according to an embodiment of the present invention.
DESCRIPTION OF THE EMBODIMENTS
An exemplary embodiment of the present invention will now be
described in detail with reference to the drawings.
FIG. 1 is a perspective view of a recording apparatus (ink-jet
recording apparatus) for making a recording (e.g., forming images)
on sheets (recording media) by using a recording head 71 in a main
scanning direction. The recording head 71 is installed in a
carriage 50. A carriage motor 54 drives the carriage 50 to scan.
The recording apparatus also includes conveying mechanisms for
conveying the sheets in a sub scanning direction (described
below).
The recording apparatus forms images on sheets by, for example,
repeating conveyance of the sheets by a predetermined conveying
amount and scanning performed by the carriage having the recording
head installed therein.
FIG. 2 is a cross-sectional view of the recording apparatus. The
recording apparatus includes a conveying roller 36, eject rollers
40 and 41, and a feeding roller 80. The feeding roller 80 picks up
a sheet from a paper feeding tray disposed in a lower portion of
the apparatus. The sheet picked up by the feeding roller 80 is
conveyed to the conveying roller 36 via a first intermediate roller
81 and a second intermediate roller 82. The conveying path during
these operations is U-shaped when viewed in section as shown in
FIG. 2. The sheet is further conveyed by the conveying roller 36
and the eject rollers. An image is formed on the sheet in an area
between the conveying roller 36 and the eject roller 40.
FIG. 3 is a cross-sectional view of the conveying mechanisms of the
recording apparatus. The driving force of a DC motor 35 is
transmitted to a pulley 361 disposed on the shaft of the conveying
roller 36 via a timing belt 39 so as to drive the conveying roller
36.
Moreover, a code wheel 362 used for detecting the conveying amount
by the conveying roller 36 is disposed on the shaft of the
conveying roller 36. An encoder sensor 363 for reading out marks on
the code wheel 362 is disposed on a chassis adjacent to the code
wheel 362. In FIG. 3, the sheet is conveyed from left to right.
The drive of the conveying roller 36 is transmitted to the eject
roller 40 via an idler gear 45. A code wheel 402 used for detecting
the conveying amount by the eject roller 40 is disposed on the
shaft of the eject roller 40, and an encoder sensor 403 for reading
out marks on the code wheel 402 is disposed on the chassis adjacent
to the code wheel 402.
As shown in FIG. 11, the conveying roller 36 and a pinch roller 37
form a nip line N. A position A is located upstream of the nip line
in the conveying direction, and is separated from the nip line by a
distance L1. A position B is located downstream of the nip line in
the conveying direction, and separated from the nip line by a
distance L2. The distances L1 and L2 are determined in accordance
with the diameters, materials, and positions of the conveying
roller 36 and the pinch roller 37, the thickness of the sheet, and
the like. Herein, the position A is a downstream boundary of an
area where the sheet can stably stop when the trailing end of the
sheet stops in this area. On the other hand, the position B is a
downstream boundary of an area where the sheet cannot stably
stop.
Next, FIG. 4 illustrates a flow of a conveying sequence before and
after a sheet passes through the conveying roller. FIG. 4
illustrates a one-pass recording mode in which the recording head
scans over a predetermined area on a sheet only one time so as to
form an image in the predetermined area.
FIG. 4 shows positions of the trailing end of the sheet on a
conveying path and conveying amounts of the sheet during conveying
operations. As in FIG. 9, each arrow indicates one conveying
operation. Marks F.sub.1, F.sub.2, and F.sub.3 indicate conveying
operations by predetermined conveying amounts. In FIG. 4, a control
unit changes the conveying amount for every conveying operation
such that the trailing end of the sheet stops in areas other than
the unstable stop area (between the positions A and B).
In FIG. 4, the conveying operation F.sub.1 is performed in a normal
feed area. When the conveying operation F.sub.1 is performed two
more times after a page end (PE) sensor detects the trailing end of
the sheet, the trailing end of the sheet reaches a position C. The
position C is a predetermined position on the conveying path. When
the trailing end of the sheet reaches the position C or a position
downstream of the position C in the conveying direction, the
control unit performs the conveying operation F.sub.v on the basis
of the distance between the position A and the position of the
trailing end of the sheet.
This conveying operation F.sub.v allows the trailing end of the
sheet to reliably stop in a predetermined area (predetermined
range) on the conveying path having a width .alpha. located
upstream of the position A in the conveying direction after the
subsequent conveying operation F.sub.2 is performed four times
(FIG. 4).
When the trailing end of the sheet stops in this predetermined area
(predetermined range), the trailing end of the sheet can pass
through the unstable stop area and can stop in a stable stop area
located downstream of the position B by conveying the sheet by a
conveying amount corresponding to the distance AB+.alpha..
Thus, the conveying operation is controlled by, for example,
controlling the distance from the position of the trailing end of
the sheet to the position A using the information of the encoder
after the PE sensor detects the trailing end of the sheet.
The conveying sequence is not limited to that shown in FIG. 4.
Another conveying sequence will now be described with reference to
FIG. 12. FIG. 12 illustrates a three-pass recording mode in which
the recording head scans over a predetermined area on a sheet three
times so as to form an image in the predetermined area. Conveying
operations performed in the three-pass mode are represented as
F.sub.1a, F.sub.2a, and F.sub.va so as to be distinguishable from
those in the one-pass mode.
When the trailing end of the sheet that has been conveyed during
the conveying operations F.sub.1a reaches the position C (or a
position downstream of the position C in the conveying direction
(left side)), the conveying operation F.sub.2a is performed three
times, and then the conveying operation F.sub.va is performed one
time. The number of executions of the conveying operation F.sub.2a
corresponds to the number of times scanning is performed by the
recording head in the recording mode, i.e., three herein.
Therefore, the number of executions of the conveying operation in
this area becomes four in a four-pass recording mode.
The number of nozzles used for a scan (or the number of times
scanning is performed over a predetermined area on the sheet) and
the above-described information on the conveying amount by which
the sheet is conveyed during one conveying operation for each
recording mode are retained in a memory of the recording apparatus.
A CPU 100 controls the recording operation and the conveying
operation on the basis of the recording mode. Thus, the trailing
end of the sheet can pass through the unstable stop area regardless
of the recording mode.
FIG. 5 is a control flow of recording on a sheet in the recording
apparatus. A sheet is fed in Step S1, and the recording head scans
over the sheet in Step S2. The sheet is conveyed in Step S3. In
Step S4, it is determined whether or not a recording of one page is
finished. For example, it is determined whether or not all the data
sent from a host is recorded. When it is determined that the
recording of one page is finished, the process proceeds to Step S5.
On the other hand, when it is determined that the recording is not
finished, the process returns to Step S2. The sheet is ejected in
Step S5.
FIG. 6 is a control flow of a conveying operation performed by the
recording apparatus. This flow is conducted for every conveying
operation. Herein, the conveying operation F.sub.1 is performed at
the beginning. In order to simplify explanation, the process of
scanning performed by the recording head is omitted. The sheet is
conveyed in Step S11. When FIG. 4 is taken for instance, the
conveying operation performed in Step S11 can be selected from any
of F.sub.2, F.sub.3, and F.sub.v instead of F.sub.1. In Step S12,
it is determined whether or not the trailing end of the sheet has
passed through the position of the PE sensor lever. When it is
determined that the trailing end of the sheet has passed through
the position of the PE sensor lever in Step S12, the process
proceeds to Step S13. The conveying operation F.sub.1 is performed
until it is determined that the trailing end of the sheet has
passed through the position of the PE sensor lever in Step S12, and
the process ends without performing Step S13 or later. When it is
necessary to acquire the position of the trailing end of the sheet
on the conveying path, the encoder provided for the conveying
roller can be used.
In Step S13, it is determined whether or not the trailing end of
the sheet has passed through the position C by the conducted
conveying operation as shown in FIG. 4 on the basis of the
information on the position of the trailing end of the sheet. When
it is determined that the trailing end of the sheet has passed
through the position C, the process proceeds to Step S14. In Step
S14, the conveying amount during the conveying operation F.sub.v is
acquired. The process in Step S14 is performed only one time while
a sheet is conveyed. After the conveying operation F.sub.v is
performed one time, the process proceeds to Step S15 regardless of
the position of the trailing end of the sheet. In Step S13, it can
be further determined whether or not the conveying operation
F.sub.v has been performed.
On the other hand, when it is determined that the trailing end of
the sheet has not passed through the position C or the conveying
operation F.sub.v has been performed in Step S13, the process
proceeds to Step S15. In Step S15, the conveying amount is acquired
on the basis of the information on the position of the trailing end
of the sheet.
In Step S14, the distance from the position of the trailing end of
the sheet to the position A is divided by a line feed amount Q, and
the conveying amount during the conveying operation F.sub.v is
determined on the basis of the remainder. Instead of the
above-described method in which arithmetic processing is performed,
a table of information on conveying amounts can be prepared in
advance. Specifically, a table of conveying amounts during the
conveying operation F.sub.v based on the distances from the
positions of the trailing end of the sheet to the position A and
the line feed amount Q is retained in the memory in advance. The
value of the conveying amount can be acquired from this table on
the basis of the information on the distance from the position of
the trailing end of the sheet to the position A.
As described above, the CPU 100 controls the conveying amount and
the nozzles of the recording head to be used on the basis of the
information on the position of the trailing end of the sheet or on
the distance from the position of the trailing end of the sheet to
the position A. In order to realize the above-described control, a
table of conveying amounts during the conveying operations F.sub.1,
F.sub.2, F.sub.3, and F.sub.v corresponding to the information on
the positions of the trailing end of the sheet and a table of
information on the number and positions of the nozzles used for
recording, for example, can be prepared.
FIG. 7 is a conceptual diagram illustrating the relationship among
the position of the trailing end of the sheet on the conveying
path, the conveying amount during a conveying operation, which are
described with reference to FIGS. 4 and 12, and the number of
nozzles of the recording head (nozzle row) to be used when a
multi-pass recording is performed. FIG. 7 illustrates the relative
positional relationship between the sheet and the recording head.
In the actual apparatus, the sheet is moved in the conveying
direction, i.e., the recording head is not moved in the conveying
direction. However, it is assumed that the position of the
recording head is changed in the conveying direction in FIG. 7 for
ease of explanation.
In FIG. 7, the length of the nozzle row of the recording head (or
the number of nozzles in the nozzle row) is defined as P. The
slender rectangles each indicate a nozzle row. Herein, the
rectangles are sectioned into three or four blocks. The shaded
areas indicate areas in use, and unshaded areas indicate unused
areas. Lower portions of the rectangles are located downstream in
the conveying direction, and upper portions of the rectangles are
located upstream in the conveying direction.
In FIG. 7, a three-pass recording is performed. At first, all the
nozzles are used for recording. However, the number of unused
nozzles is increased to P/8, 3P/16, or P/4 as the recording
operation proceeds. This is because the positions of the nozzles to
be used are shifted when a recording is made on the trailing end
portion of the sheet.
Numbers 71 to 77 each indicate a conveying operation, and the
conveying operations 71 to 77 are performed in order. Moreover, the
conveying amounts during the conveying operations 71 to 73 are set
to 6P/16 or 5P/16. That is, when the conveying amounts during the
three conveying operations 71 to 73 are 6P/16, 5P/16, and 5P/16,
respectively, the total conveying amount becomes equal to the
length P of the nozzle row.
As described above, after the trailing end of the sheet is detected
by the PE sensor, the number of nozzles used for recording is
reduced in accordance with the progress of the sheet.
In an exemplary embodiment, the number of nozzles in the nozzle row
is 512, for example. When the number of nozzles to be used is
limited to 3/4, the number of nozzles to be used becomes 384.
In the three-pass recording, the conveying amount during one
conveying operation in an area where the number of nozzles is
limited (nozzle limited area) becomes P/4 (=128 nozzles).
The conveying amounts during the conveying operations 71 to 73 each
correspond to that during the conveying operation F.sub.1a shown in
FIG. 12. The conveying amount of P/4 during the conveying
operations 74 to 77 corresponds to that during the conveying
operation F.sub.2a shown in FIG. 12. In this manner, the conveying
amounts in an exemplary embodiment can be increased as compared
with that of P/8 during the conveying operation in the known
technology described above. In FIG. 7, the conveying amount during
the conveying operation F.sub.va (described below) is set to
P/4.
FIG. 8 illustrates the conveying amounts before and after the
trailing end of the sheet passes through the unstable stop area and
the nozzles of the recording head to be used in the one-pass
recording mode.
The processes shown in FIG. 8 proceed from top to bottom. The
recording operation on the sheet will be described from the middle
of the flow for ease of explanation. Herein, for example, processes
after the trailing end of the sheet reaches the position C on the
conveying path shown in FIG. 4 will be described. A sequence of the
recording operations and the conveying operations is described.
This sequence is performed from Process R1 in order.
First, a recording operation using the first to three hundred
eighty-fourth nozzles in the nozzle row downstream in the conveying
direction is performed (Process R1). A mark P.sub.N indicates Nth
scanning by the recording head over the sheet. Next, a conveying
operation by a conveying amount of Q+q is performed (Process R2).
This conveying operation corresponds to the conveying operation
F.sub.v shown in FIG. 4, and the conveying amount during this
conveying operation corresponds to the length of 416 nozzles. Next,
a recording operation using 384 nozzles from the thirty-third
nozzle in the nozzle row downstream in the conveying direction is
performed (Process R3). The number of nozzles to be used is not
changed. However, the nozzles to be used are changed. A mark
P.sub.N+1 indicates (N+1)th scanning by the recording head.
Next, a conveying operation by a conveying amount of Q is performed
(Process R4). This conveying operation corresponds to the conveying
operation F.sub.2 shown in FIG. 4, and the conveying amount during
this conveying operation corresponds to the length of 384 nozzles.
After this, the recording operation using the 384 nozzles from the
thirty-third nozzle and the conveying operation by the conveying
amount of Q are repeated. Subsequently, the recording operation
using the 384 nozzles from the thirty-third nozzle is performed
((N+m)th scanning; Process R5). Next, a conveying operation by a
conveying amount of R is performed (Process R6). This conveying
operation corresponds to the conveying operation F.sub.3 shown in
FIG. 4. Next, a recording operation using 384 nozzles from the
sixty-fifth nozzle in the nozzle row downstream in the conveying
direction is performed (Process R7). Since the conveying amount of
R is larger than that during the conveying operation F.sub.2, the
difference is adjusted by changing the nozzles to be used for
recording.
As a postscript, the position of the trailing end of the sheet is
detected and the information on the distance from the position of
the trailing end of the sheet to the position of the conveying
roller 36 is acquired every conveying operation. The subsequent
conveying operation is performed using the conveying amount based
on the acquired information on the distance.
In FIG. 8, the one-pass recording mode is described, and the number
of nozzles to be used is 384. In a three-pass recording mode, one
third of 384 nozzles, i.e., 128 nozzles are used for recording.
Moreover, the conveying amount during the conveying operation
F.sub.2a becomes the length corresponding to 128 nozzles, and the
conveying amount during the conveying operation F.sub.va becomes
the length corresponding to 160 nozzles (=128+32).
In this exemplary embodiment, the conveying amounts are selected
from any of Q, Q+q, Q+2q, and Q+3q on the basis of the distance to
the conveying roller 36 (or distance to the position A shown in
FIG. 4). As described with reference to FIG. 6, the distance is
divided by the line feed amount Q so as to determine the remainder.
The conveying amount during the conveying operation F.sub.v is
determined from this remainder in units of q=Q/4, for example. The
conveying amounts can be determined from a table of conveying
amounts corresponding to the distances from the positions where
(the trailing end of) a recording sheet stops to the position of
the conveying roller 36.
The position of the trailing end of the recording sheet when the
conveying operation F.sub.3 is started can be controlled by
adjusting the conveying amount during the conveying operation
F.sub.v. With this, the trailing end of the recording sheet can be
reliably prevented from stopping in the unstable stop area.
Next, the above-described control flow will be briefly described.
First, when the trailing end of a sheet that is being conveyed is
detected by the PE sensor, the number of nozzles to be used is
gradually reduced for every recording operation while the recording
operations and the conveying operations are performed (for example,
the number of nozzles to be used is gradually reduced to 384).
After the number of nozzles is reduced to a desired value, a
conveying amount during an adjustment feed is acquired on the basis
of the distance from the position where (the trailing end of) the
recording sheet stops to the position of the conveying roller 36.
Subsequently, the conveying operation F.sub.v (adjustment feed by
the conveying amount of Q+q; see Process R2 in FIG. 8) is performed
on the basis of the acquired conveying amount (for example, one
time). After this, the conveying operation F.sub.2 by a conveying
amount corresponding to the number of nozzles to be used (384;
conveying amount of Q; see Process R4 in FIG. 8) is performed.
However, when the conveying operation for passing through the nip
formed by the conveying roller 36 is required, the conveying
operation F.sub.3 (conveying amount of R; see Process R6 in FIG. 8)
is performed. The recording operation after the conveying operation
F.sub.3 is performed by changing the positions of nozzles to be
used (see Process R7 in FIG. 8). After this, the conveying
operation F.sub.2 (conveying amount of Q; see Process R8 in FIG. 8)
by the conveying amount corresponding to the number of nozzles to
be used (384) and the recording operation using the nozzles shown
in Process R7 in FIG. 8 are performed. In this manner, the control
of the conveying amount and the selection of the nozzles to be used
are performed after the trailing end of the sheet is detected by
the PE sensor.
FIG. 10 is a control block diagram of the recording apparatus
according to this exemplary embodiment. The CPU 100 executes
control programs stored in a ROM 101, and performs the programs in
accordance with, for example, the control flows shown in FIGS. 5
and 6. Moreover, the ROM 101 also stores the above-described data
of the conveying amounts. A RAM 102 is a working memory. A motor
driver 104 drives the DC motor 35. A motor driver 105 drives a DC
motor 54. An ASIC 103 processes information output from the encoder
sensors 363 and 403. The conveying operations are performed by
controlling the DC motor 35.
According to the above-described structure, it is not necessary to
reduce the conveying amount of a sheet in the nozzle limited area
and the number of nozzles to be used beyond necessity. Therefore,
throughput during the recording operations can be increased.
While the present invention has been described with reference to
exemplary embodiments, it is to be understood that the invention is
not limited to the disclosed exemplary embodiments. The scope of
the following claims is to be accorded the broadest interpretation
so as to encompass all modifications, equivalent structures and
functions.
This application claims the priority of Japanese Application No.
2006-226701 filed Aug. 23, 2006, which is hereby incorporated by
reference herein in its entirety.
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