EP0835025A2
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EP
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Printing system and image recording method
Assignee: Seiko Epson Corp
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Filing: 1997-10-01
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Granted: —
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Expires: 2017-10-01
Abstract
Abstract In a printer for printing an image by a distribution of dots having different densities per unit area or dots having different hues, the structure of the present invention accurately determines the on/off state of the different dots and ensures high quality printing. Recording ratios Rn and Rt of deep dots and light dots corresponding to input tone data DS in a target pixel are read from a map representing the relationship between the recording ratios and the tone data. The systematic dither method is adopted to determine formation or non-formation of a deep dot in the target pixel. This method compares the recording radio Rn of deep dots with a threshold value Dref corresponding to the target pixel and read from a threshold matrix TM. In the case where a deep dot is not formed, the recording ratio Rt of light dots is corrected by adding the recording ratio Rn of deep dots and subsequently compared with the same threshold value Dref to determine formation or non-formation of a light dot in the target pixel. The structure of the present invention uses only one threshold matrix to realize desired recording ratios without causing any overlap of deep dots with light dots. This structure is also applicable to dots having different hues. In this case, one threshold matrix is used to determine the on/off state of dots having different hues without causing any interference of the different hues.
Inventors
- 👤 Toshiaki Kakutani
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-10 02:37
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/40087; H04N1/46; H04N1/52
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
271 words
A printing system having a head, from which inks are
dischargeable to record at least two different dots having
different characteristics on an object, and recording a multi-tone
image by a distribution of said at least two different dots, said
printing system comprising: input means for successively receiving a tone signal of each
pixel included in an image to be printed; recording ratio setting means for specifying recording ratios
of said at least two different dots having different
characteristics with respect to said each pixel, based on said
input tone signal; first dot formation determination means for comparing the
recording ratio specified for a first dot among said at least two
different dots having different characteristics with a threshold
value corresponding to said each pixel and read from a threshold
matrix, which corresponds to a dither pattern provided in advance,
in order to determine whether or not said first dot is to be formed
at a position corresponding to said each pixel; second dot formation determination means for comparing the
recording ratio specified for a second dot among said at least
two different dots having different characteristics with the
threshold value of said threshold matrix, in order to determine
whether or not said second dot is to be formed at a position
corresponding to said each pixel, except positions corresponding
to the pixels where formation of said first dot has been determined;
and head driving means for driving said head to form said at least
two different dots having different characteristics, based on the
results of determination by said first dot formation determination
means and said second dot formation determination means.
Claim 2
Dependent Claim
93 words
A printing system in accordance with claim 1, wherein said
second dot formation determination means corrects the recording
ratio of said second dot with the recording ratio of said first
dot used for the comparison in said first dot formation
determination means, and compares the corrected recording ratio
with the threshold value of said threshold matrix, in order to
determine whether or not said second dot is to be formed at a
position corresponding to said each pixel, except positions
corresponding to the pixels where formation of said first dot has
been determined.
Claim 3
Dependent Claim
51 words
A printing system in accordance with claim 2, wherein said
second dot formation determination means corrects the recording
ratio of said second dot by adding the recording ratio of said
first dot used for the comparison in said first dot formation
determination means to the recording ratio of said second dot.
Claim 4
Dependent Claim
109 words
A printing system in accordance with claim 1, wherein said
second dot formation determination means subtracts a value
corresponding to the recording ratio of said first dot used for
the comparison in said first dot formation determination means
from the corresponding threshold value of said threshold matrix
to give a corrected threshold matrix, and compares the recording
ratio of said second dot with the corrected threshold value of
said corrected threshold matrix, in order to determine whether
or not said second dot is to be formed at a position corresponding
to said each pixel, except positions corresponding to the pixels
where formation of said first dot has been determined.
Claim 5
Dependent Claim
88 words
A printing system in accordance with claim 1, wherein said
second dot formation determination means reverses the magnitude
of the threshold values in said threshold matrix to give a reverse
threshold matrix, and compares the recording ratio of said second
dot with the reverse threshold value of said reverse threshold
matrix, in order to determine whether or not said second dot is
to be formed at a position corresponding to said each pixel, except
positions corresponding to the pixels where formation of said first
dot has been determined.
Claim 6
Dependent Claim
113 words
A printing system in accordance with claim 5, wherein said
second dot formation determination means comprises total recording ratio judgement means for determining whether
or not a sum of the recording ratio of said first dot used for
the determination by said first dot formation determination means
and the recording ratio of said second dot used for the
determination by said second dot formation determination means
exceeds 100[%], wherein the recording ratio of said second dot is compared
with the reverse threshold value of said reverse threshold matrix,
when said total recording ratio judgement means determines that
the sum of the recording ratios of said first dot and said second
dot exceeds 100[%].
Claim 7
Dependent Claim
49 words
A printing system in accordance with any of claims 1 to 6,
wherein said at least two different dots having different
characteristics are at least two different dots having different
densities per unit area, said head forming said at least two different dots having
different densities per unit area.
Claim 8
Dependent Claim
54 words
A printing system in accordance with any of claims 1 to 6,
wherein said at least two different dots having different
characteristics are at least two different dots having different hues, at least two inks of different hues being dischargeable from
said head to form said at least two different dots having different
hues.
Claim 9
Dependent Claim
33 words
A printing system in accordance with any preceding claim,
wherein said threshold matrix used by said first dot formation
determination means and said second dot formation determination means
is a discrete threshold matrix.
Claim 10
Dependent Claim
45 words
A printing system in accordance with any preceding claim,
wherein said head comprises a mechanism for discharging ink particles
under a pressure applied to each ink running through an ink conduit
by application of a voltage to a piezoelectric element arranged in
said ink conduit.
Claim 11
Dependent Claim
54 words
A printing system in accordance with any of claims 1 to 9,
wherein said head comprises a mechanism for discharging ink particles
under a pressure applied to each ink running through an ink conduit
by air bubbles that are produced by a supply of electricity to a
heating body arranged in said ink conduit.
Claim 12
Dependent Claim
42 words
A printing system in accordance with claim 7, wherein said
first dot formation determination mean carries out the
determination for a dot having a higher density per unit area among
said at least two different dots having different densities per
unit area.
Claim 13
Dependent Claim
42 words
A printing system in accordance with claim 7, wherein said
first dot formation determination means carries out the
determination for a dot having a lower density per unit area among
said at least two different dots having different densities per
unit area.
Claim 14
Dependent Claim
70 words
A printing system in accordance with claim 7, 12 or 13,
wherein said at least two different dots having different densities
per unit area are recorded by at least two inks of different
densities, said at least two inks of different densities comprising
a high-density ink and a low density ink and a dye density of said
low-density ink being approximately one quarter a dye density of said
high-density ink.
Claim 15
Dependent Claim
28 words
A printing system in accordance with claim 14, wherein
said head discharges said high-density ink and said low-density
ink for at least either one of cyan and magenta.
Claim 16
Dependent Claim
23 words
A printing system in accordance with claim 7, 12 or 13,
wherein said head forms at least two different dots having different
diameters.
Claim 17
Dependent Claim
39 words
A printing system in accordance with claim 8, wherein said
first dot formation determination means carries out the
determination for a dot having a hue of greater visual effect among
said at least two different dots having different hues.
Claim 18
Dependent Claim
79 words
A printing system in accordance with claim 8, wherein said
head records an image by dots in at least cyan, magenta, yellow,
and black inks, said first dot formation determination means carrying out the
determination for a dot of said black ink among said at least two
different dots having different hues, said second dot formation determination means carrying out
the determination for a dot of said yellow ink among said at least
two different dots having different hues.
Claim 19
Dependent Claim
83 words
A printing system in accordance with claim 8, wherein said
head records an image by dots in at least cyan, magenta, yellow,
and black inks, said first dot formation determination means carrying out the
determination for a dot of said black ink among said at least two
different dots having different hues, said second dot formation determination means carrying out
the determination for a dot of said magenta ink or said cyan ink
among said at least two different dots having different hues.
Claim 20
Dependent Claim
117 words
A printing system in accordance with claim 19, said
printing system further comprising: third dot formation determination means for determining
whether or not third dots are to be formed by an ink of another
hue after the determination by said second dot formation
determination means, said another hue being different from the
hue of said ink that is subjected to the determination by said
second dot formation determination means; and dot position determination means for, when said third dot
formation determination means determines formation of said third
dots by said ink of another hue, reading the threshold values from
said threshold matrix in a reverse order of magnitude, so as to
determine positions of said third dots.
Claim 21
Dependent Claim
91 words
A printing system in accordance with claim 20, said
printing system further comprising: yellow dot formation determination means for determining
whether or not yellow dots are to be formed by said yellow ink;
and yellow dot position determination means for, when said yellow
dot formation determination means determines formation of said
yellow dots by said yellow ink, determining positions of said
yellow dots, in order to avoid an overlap with positions of black
dots by said black ink that are subjected to the determination
by said first dot formation determination means.
Claim 22
Dependent Claim
256 words
An image recording method for recording a multi-tone image
by a distribution of at least two different dots having different
characteristics in a printing system with a head, from which inks
are dischargeable to record said at least two different dots having
different characteristics on an object, said method comprising
the steps of: (a) successively receiving a tone signal of each pixel
included in an image to be printed; (b) specifying recording ratios of said at least two different
dots having different characteristics with respect to said each
pixel, based on said input tone signal; (c) comparing the recording ratio specified for a first dot
among said at least two different dots having different
characteristics with a threshold value corresponding to said each
pixel and read from a threshold matrix, which corresponds to a
dither pattern provided in advance, in order to determine whether
or not said first dot is to be formed at a position corresponding
to said each pixel; (d) comparing the recording ratio specified for a second dot
among said at least two different dots having different
characteristics with the threshold value of said threshold matrix,
in order to determine whether or not said second dot is to be formed
at a position corresponding to said each pixel, except positions
corresponding to the pixels where formation of said first dot has
been determined; and (e) driving said head to form said at least two different dots
having different characteristics, based on the results of
determination in said step (c) and said step (d).
Claim 23
Dependent Claim
88 words
An image recording method in accordance with claim 22,
wherein said step (d) corrects the recording ratio of said second
dot with the recording ratio of said first dot used for the
comparison in said step (c), and compares the corrected recording
ratio with the threshold value of said threshold matrix, in order
to determine whether or not said second dot is to be formed at
a position corresponding to said each pixel, except positions
corresponding to the pixels where formation of said first dot has
been determined.
References Cited (Backward Citations)
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