Patent US5576706A successfully refreshed from Google Patents.
Patent EP0895869A2 successfully refreshed from Google Patents.
EP0895869A2
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Method of printing test pattern and printing apparatus for the same
Assignee: Seiko Epson Corp
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Filing: 1998-07-31
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Granted: —
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Expires: 2018-07-31
Abstract
Abstract In a printer that allows dual-way printing, a test pattern is formed to adjust the print timing with high accuracy, i.e. to eliminate a deviation of dots created in the course of a main scan in both a backward and forward direction. The test pattern is based on a normal dither matrix, and includes a plurality of dots regularly arranged both in a main scanning direction and in a sub-scanning direction. When the test pattern is printed at an appropriate timing, it is seen as a substantially homogeneous state without unevenness of density (Fig.8). Where dot print timing is deviated, on the other hand, a deviation in dot interval causes unevenness of density (Fig. 9). The deviation of the dot print timing is accurately detected based on the presence or the non-presence of such unevenness. When the interval of the dots is set equal to an interval that realizes a spatial frequency giving a high visual sensitivity, unevenness of the density is more prominently observable. The deviation of the dot print timing may alternatively be detected by taking advantage of a moire pattern, which is caused by an overlap of an inspection pattern, e.g. parallel lines or a normal dither matrix, with reference lines, e.g. oblique or vertical parallel lines.
Inventors
- 👤 Kazumichi Shimada
- 👤 Sa Ryu
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 14:02
CPC Classifications
B; B41; B41J; B41J19/00; B41J19/14; B41J19/142; B41J19/145; B41J29/00; B41J29/38; B41J29/393
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
238 words
A method of printing a test pattern on a printing medium by
driving a print head to create dots while carrying out a main scan, which
moves said print head forward and backward relative to said printing
medium in a main scanning direction, said method comprising the steps of: (a) creating dots at a first timing that forms a first pattern in the
course of the main scan in the forward direction, wherein said first pattern
comprises a dark portion having a certain area and a light portion having
an area greater than the area of said dark portion that alternately appear
at a first cycle in the main scanning direction in a predetermined first
section of said printing medium; and (b) creating dots at a second timing that are supposed to form a
second pattern in the course of the main scan in the backward direction,
wherein said second pattern comprises a dark portion having a certain area
and a light portion having an area greater than the area of said dark
portion that alternately appear at a second cycle in the main scanning
direction in a predetermined second section of said printing medium, said
predetermined second section at least partly overlapping said
predetermined first section, and wherein said dark portion of said first
pattern and said dark portion of said second pattern appear at a fixed
interval in the main scanning direction in said overlapped area.
Claim 2
Dependent Claim
125 words
A method in accordance with claim 1, wherein said step (a)
creates a plurality of dots that are apart from each other by a
predetermined first interval in the main scanning direction and apart from
each other by a predetermined second interval in a sub-scanning direction,
and wherein said step (b) creates a plurality of dots at positions that are
to satisfy at least either one of a position that is apart from each of said
plurality of dots created in said step (a) by approximately half the
predetermined first interval in the main scanning direction and a position
that is apart from each of said plurality of dots created in said step (a) by
approximately half the predetermined second interval in the sub-scanning
direction.
Claim 3
Dependent Claim
65 words
A method in accordance with claim 1 or 2, wherein either one of said
step (a) and said step (b) forms a third pattern superposed upon said first
pattern and said second pattern, said third pattern enabling a relative
deviation of a printing position of said second pattern from a printing
position of said first pattern to be observed as the appearance of light-dark
stripes.
Claim 4
Dependent Claim
279 words
A printing apparatus that drives a print head to create dots while
carrying out a main scan, which moves said print head forward and
backward relative to said printing medium in a main scanning direction,
said printing apparatus carrying out a sub-scan that moves said printing
medium relative to said print head in a sub-scanning direction, which is
perpendicular to the main scanning direction, thereby printing an image on
said printing medium, said printing apparatus comprising: a forward-course pattern formation unit that drives said print head
at a first timing that forms a first pattern in the course of the main scan in
the forward direction, wherein said first pattern comprises a dark portion
having a certain area and a light portion having an area greater than the
area of said dark portion that alternately appear at a first cycle in the main
scanning direction in a predetermined first section of said printing medium;
and a backward-course pattern formation unit that drives said print
head at a second timing that is supposed to form a second pattern in the
course of the main scan in the backward direction, wherein said second
pattern comprises a dark portion having a certain area and a light portion
having an area greater than the area of said dark portion that alternately
appear at a second cycle in the main scanning direction in a predetermined
second section of said printing medium, said predetermined second section
at least partly overlapping said predetermined first section, and wherein
said dark portion of said first pattern and said dark portion of said second
pattern appear at a fixed interval in the main scanning direction in said
overlapped area.
Claim 5
Dependent Claim
144 words
A printing apparatus in accordance with claim 4, wherein said
forward-course pattern formation unit drives said print head to create a
plurality of dots that are apart from each other by a predetermined first
interval in the main scanning direction and apart from each other by a
predetermined second interval in a sub-scanning direction, and wherein said backward-course pattern formation unit drives said
print head to create a plurality of dots at positions that are to satisfy at
least either one of a position that is apart from each of said plurality of dots
created by said forward-course pattern formation unit by approximately
half the predetermined first interval in the main scanning direction and a
position that is apart from each of said plurality of dots created by said
forward-course pattern formation unit by approximately half the
predetermined second interval in the sub-scanning direction.
Claim 6
Dependent Claim
58 words
A printing apparatus in accordance with claim 4 or 5, wherein said
print head comprises a plurality of nozzles that are disposed at a
predetermined nozzle interval, which is greater than a printing pitch of dots
in the sub-scanning direction, one of the predetermined second interval and the predetermined
nozzle interval being an integral multiple of the other.
Claim 7
Dependent Claim
34 words
A printing apparatus according to claim 4, 5 or 6, wherein said
first pattern and said section pattern comprise a plurality of parallel lines
arranged at an equal interval in the main scanning direction.
Claim 8
Dependent Claim
50 words
A printing apparatus in accordance with any of claims 4 to 7, wherein said
dark portion of said first pattern and said dark portion of said second
pattern alternately appear in the main scanning direction at a spatial
frequency of 0.4 to 2.0 cycles / mm in said overlapped area.
Claim 9
Dependent Claim
77 words
A printing apparatus in accordance with any of claims 4 to 8, wherein either
one of said forward-course pattern formation unit and said backward-course
pattern formation unit drives said print head to form a third pattern
superposed upon said first pattern and said second pattern, said third
pattern enabling a relative deviation of a printing position of said second
pattern from a printing position of said first pattern to be observed as
the appearance of light-dark stripes.
Claim 10
Dependent Claim
23 words
A printing apparatus in accordance with claim 9, wherein said
third pattern comprises a plurality of parallel lines arranged at a fixed
interval.
Claim 11
Dependent Claim
31 words
A printing apparatus in accordance with claim 9 or 10, wherein
each of said first pattern and said second pattern comprises a plurality of
parallel lines arranged at a predetermined interval.
Claim 12
Dependent Claim
38 words
A printing apparatus in accordance with claim 9, wherein said
third pattern comprises a plurality of parallel lines that obliquely intersect
a plurality of parallel lines constituting said first pattern and said second
pattern at a predetermined angle.
Claim 13
Dependent Claim
28 words
A printing apparatus in accordance with claim 12, wherein said
predetermined angle is in a range of not less than 2 degrees and not greater
than 10 degrees.
Claim 14
Dependent Claim
67 words
A printing apparatus in accordance with any of claims 9 to 13, said
printing apparatus further comprising: a camera with which a pattern printed on said printing medium is
shot; and a detection unit that detects the relative deviation of the printing
position of said second pattern from the printing position of said first
pattern based on light-dark stripes appearing in said pattern shot with said
camera.
Claim 15
Dependent Claim
109 words
A printing apparatus in accordance with claim 4, said printing
apparatus further comprising: a single-way pattern formation unit that drives said print head
during the main scan only either in the forward direction or in the
backward direction to print a pattern that is to be formed by both said
forward-course pattern formation unit and said backward-course pattern
formation unit in a specific area on said printing medium, said specific area
being different from said predetermined first section in which said first
pattern is formed by said forward-course pattern formation unit and said
predeterniined second section in which said second pattern is formed by
said backward-course pattern formation unit.
Claim 16
Dependent Claim
96 words
A printing medium used in a method of printing a test pattern in
accordance with claim 1, wherein a test pattern to be formed in said step (a)
and in said step (b) is printed in advance in a specified area at an optimum
dot formation timing during the main scan in the backward direction,
wherein said specified area at least partly does not overlap said
predetermined first section in which said first pattern is formed in said step
(a) or said predetermined second section in which said second pattern is
formed in said step (b).
Claim 17
Dependent Claim
112 words
An inspection printing medium used in a method of printing a
test pattern in accordance with claim 1, said inspection printing medium
having a third pattern that is printed in advance in a specified area of said
inspection printing medium, wherein said specified area at least partly
overlaps said predetermined first section in which said first pattern is
formed in said step (a) and said predetermined second section in which said
second pattern is formed in said step (b), and wherein said third pattern
enables a relative deviation of a printing position of said second pattern
from a printing position of said first pattern to be observed as appearance of
light-dark stripes.
Claim 18
Independent Claim
121 words
A method of designing a test pattern for a printer that creates dots
while carrying out a main scan and moves a print head forward and backward
relative to a printing medium, the pattern being formed by the main scan both
in the forward direction and in the backward direction, wherein said test pattern comprises a plurality of dots created at a
predetermined interval in a predetermined area, and said method comprising the steps of: specifying a spatial frequency that gives a maximum visual
sensitivity of a human's eye with respect to lightness; and determining said predetermined interval of said dots, in order to
cause a spatial frequency of said test pattern to be substantially equal to
said specified spatial frequency.
Claim 19
Independent Claim
119 words
A method of printing a test pattern on a print medium by
driving a print head to create dots while carrying out a main scan in forward
and backward scanning directions, the method comprising the steps of: creating a first pattern during a forward scan comprising alternating
dark and light portions, the light portions being greater in area than the dark
portions; and creating a second pattern during a backward scan comprising
alternating dark and light portions, the light portions being greater in area
than the dark portions and the second pattern overlapping the first pattern,
the dark portions of the first and second patterns, when print timing is
appropriate, being regularly spaced apart in the main scanning direction.
References Cited (Backward Citations)
JPH0781190A
Cited
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