EP1814302A2
Active / In Force
EP
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Printer, dither matrix generation method, and recording medium
Assignee: Dainippon Screen Manufacturing Co Ltd
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Filing: 2006-12-27
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Granted: —
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Expires: 2026-12-27
Abstract
Abstract A printer has a head where outlets are arranged in a width direction perpendicular to a predetermined scan direction, and a printing paper moves under the head in the scan direction. In a basic dither matrix which is an array where element values are arranged in a column direction corresponding to the scan direction and a row direction corresponding to the width direction and positions in the row direction are associated with the outlets in the head, respectively, the element values are modified on the basis of variation in print densities with respect to the width direction caused by ejection from the outlets. In the printer, printing is performed with the modified dither matrix, it is therefore possible to print an image at high speed and easily, where unevenness caused by variation in ejection amounts of droplets from the outlets or the like is suppressed.
Inventors
- 👤 Osamu c/o Dainippon Screen Mfg. Co. Ltd. Kitagawa
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 12:47
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/401; H04N1/4015; H04N1/405
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
235 words
An inkjet printer (1) for printing a halftone image generated by comparing a grayscale original image with a dither matrix, comprising: a head (21) having a plurality of outlets (611) arranged in a width direction perpendicular to a predetermined scan direction each of which ejects droplets of ink onto a printing medium (9); and a scanning mechanism (3) for moving said printing medium relatively to said head in said scan direction, and said printer characterized by a matrix memory (42) for storing a modified dither matrix (81) which is a two-dimensional array where a plurality of element values are arranged in a column direction corresponding to said scan direction and a row direction corresponding to said width direction, a plurality of positions in said row direction as many as said plurality of outlets are associated with said plurality of outlets, respectively, and said plurality of element values are modified on the basis of variation in print densities with respect to said width direction caused by ejection from said plurality of outlets; and an ejection controller (43) for controlling ejection of ink from said plurality of outlets, in accordance with comparison results between pixel values of said original image at positions of said plurality of outlets relative to said printing medium and element values of said modified dither matrix corresponding to said pixel values, in synchronization with movement of said printing medium relative to said head.
Claim 2
Dependent Claim
34 words
The printer according to claim 1, wherein said plurality of outlets in said head are arranged so as to cover an entire printing area on said printing medium with respect to said width direction.
Claim 3
Dependent Claim
77 words
The printer according to claim 1 or 2, further comprising: a density measurement part (24) for measuring densities of regions corresponding to said plurality of outlets in a predetermined pattern (5, 5 a) on said printing medium which is printed by said head with using an unmodified dither matrix; and an operation part (111) for obtaining said modified dither matrix on the basis of said unmodified dither matrix and measurement results acquired by said density measurement part.
Claim 4
Dependent Claim
44 words
The printer according to claim 3, wherein said predetermined pattern includes a plurality of pattern elements (51) corresponding to a plurality of density levels, respectively, and said measurement results are acquired through measurement of said plurality of pattern elements by said density measurement part.
Claim 5
Dependent Claim
71 words
The printer according to claim 1 or 2, wherein said head comprises a plurality of ejection modules (231) in each of which outlets are arranged at a regular ejection pitch in said width direction, and a center-to-center distance in said width direction of adjacent outlets (611a) between each combination of adjacent two of said plurality of ejection modules is equal to or longer than 0 and shorter than said ejection pitch.
Claim 6
Dependent Claim
74 words
The printer according to claim 5, further comprising: a density measurement part (24) for measuring densities of regions corresponding to said plurality of outlets in a predetermined pattern (5, 5a) on said printing medium which is printed by said head with using an unmodified dither matrix; and an operation part (111) for obtaining said modified dither matrix on the basis of said unmodified dither matrix and measurement results acquired by said density measurement part.
Claim 7
Dependent Claim
41 words
The printer according to claim 6, wherein said predetermined pattern includes position indicating parts (52) each of which is located away in said scan direction from a portion used for measurement of densities and associated with positions of said adjacent outlets.
Claim 8
Dependent Claim
40 words
The printer according to claim 7, wherein said density measurement part detects said position indicating parts, whereby a level of smoothing of measurement results is reduced in measuring densities of regions corresponding to said adjacent outlets in said predetermined pattern.
Claim 9
Dependent Claim
73 words
The printer according to claim 5, further comprising: a density measurement part (24) for measuring densities of regions corresponding to said adjacent outlets in a predetermined pattern (5, 5a) on said printing medium which is printed by said head with using an unmodified dither matrix; and an operation part (111) for obtaining said modified dither matrix on the basis of said unmodified dither matrix and measurement results acquired by said density measurement part.
Claim 10
Dependent Claim
57 words
The printer according to any one of claims 1 to 9, wherein each of said plurality of outlets can form a plurality of dots having different sizes by ejecting different amounts of droplets, and each element value of said modified dither matrix is a set of sub-element values used for determination of a size of a dot.
Claim 11
Dependent Claim
195 words
A dither matrix generation method for generating a dither matrix compared with a grayscale original image when generating a halftone image from said original image in printing in an inkjet printer (1) which comprises a head (21) having a plurality of outlets (611) arranged in a width direction perpendicular to a predetermined scan direction each of which ejects droplets of ink onto a printing medium (9), and a scanning mechanism (3) for moving said printing medium relatively to said head in said scan direction, said method characterized by a) a step (S4) of preparing a basic dither matrix (83) which is a two-dimensional array where a plurality of element values are arranged in a column direction corresponding to said scan direction and a row direction corresponding to said width direction, and a plurality of positions in said row direction as many as said plurality of outlets are associated with said plurality of outlets, respectively; and b) a step (S8) of acquiring a modified dither matrix (81) by modifying said plurality of element values on the basis of variation in print densities with respect to said width direction caused by ejection from said plurality of outlets.
Claim 12
Dependent Claim
37 words
The dither matrix generation method according to claim 11, wherein said plurality of outlets in said head are arranged so as to cover an entire printing area on said printing medium with respect to said width direction.
Claim 13
Dependent Claim
80 words
The dither matrix generation method according to claim 11 or 12, wherein said step b) comprises: b1) a step (S6) of measuring densities of regions corresponding to said plurality of outlets in a predetermined pattern (5, 5a) on said printing medium which is printed by said head with using said basic dither matrix; and b2) a step (S8) of obtaining said modified dither matrix on the basis of said basic dither matrix and measurement results acquired in said step b1).
Claim 14
Dependent Claim
46 words
The dither matrix generation method according to claim 13, wherein said predetermined pattern includes a plurality of pattern elements (51) corresponding to a plurality of density levels, respectively, and said measurement results are acquired through measurement of said plurality of pattern elements in said step b1).
Claim 15
Dependent Claim
74 words
The dither matrix generation method according to claim 11 or 12, wherein said head comprises a plurality of ejection modules (231) in each of which outlets are arranged at a regular ejection pitch in said width direction, and a center-to-center distance in said width direction of adjacent outlets (611a) between each combination of adjacent two of said plurality of ejection modules is equal to or longer than 0 and shorter than said ejection pitch.
Claim 16
Dependent Claim
78 words
The dither matrix generation method according to claim 15, wherein said step b) comprises: b1) a step (S6) of measuring densities of regions corresponding to said plurality of outlets in a predetermined pattern (5, 5a) on said printing medium which is printed by said head with using said basic dither matrix; and b2) a step (S8) of obtaining said modified dither matrix on the basis of said basic dither matrix and measurement results acquired in said step b1).
Claim 17
Dependent Claim
44 words
The dither matrix generation method according to claim 16, wherein said predetermined pattern includes position indicating parts (52) each of which is located away in said scan direction from a portion used for measurement of densities and associated with positions of said adjacent outlets.
Claim 18
Dependent Claim
44 words
The dither matrix generation method according to claim 17, wherein in said step b1), said position indicating parts are detected, whereby a level of smoothing of measurement results is reduced in measuring densities of regions corresponding to said adjacent outlets in said predetermined pattern.
Claim 19
Dependent Claim
77 words
The dither matrix generation method according to claim 15, wherein said step b) comprises: b1) a step (S6) of measuring densities of regions corresponding to said adjacent outlets in a predetermined pattern (5, 5a) on said printing medium which is printed by said head with using said basic dither matrix; and b2) a step (S8) of obtaining said modified dither matrix on the basis of said basic dither matrix and measurement results acquired in said step b1).
Claim 20
Dependent Claim
60 words
The dither matrix generation method according to any one of claims 11 to 19, wherein each of said plurality of outlets can form a plurality of dots having different sizes by ejecting different amounts of droplets, and each element value of said modified dither matrix is a set of sub-element values used for determination of a size of a dot.
Claim 21
Dependent Claim
31 words
An electronic apparatus-readable recording medium (8) characterized by recording data of a dither matrix (81) generated by the dither matrix generation method according to any one of claims 11 to 20.
Claim 22
Dependent Claim
216 words
An electronic apparatus-readable recording medium (8) in which data of a dither matrix (81) is recorded, said dither matrix being a two-dimensional array where a plurality of element values are arranged in a column direction and a row direction and being compared with a grayscale original image when generating a halftone image from said original image in recording dots in a dot recording apparatus (1) which comprises a head (21) having a plurality of dot output elements (611) for recording dots in a plurality of writing element regions, respectively, arranged in a width direction perpendicular to a predetermined scan direction on an object (9), said width direction corresponding to said row direction and said scan direction corresponding to said column direction, and a scanning mechanism (3) for moving said plurality of writing element regions on said object relatively to said object in said scan direction, said recording medium characterized in that in said dither matrix, a plurality of positions in said row direction as many as said plurality of dot output elements are associated with said plurality of dot output elements, respectively, said plurality of element values have a directional property in said column direction by modifying said plurality of element values on the basis of variation in outputs of said plurality of dot output elements.
References Cited (Backward Citations)
JP2004106248A
Cited
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