EP0863479A2
Expired / Lapsed
EP
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Method and apparatus for multipass colour ink jet printing
Assignee: HP Inc
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Filing: 1998-03-03
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Granted: —
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Expires: 2018-03-03
Abstract
Abstract Bidirectional scanning printheads (20, 20', 23-26) discharge color-ink drops (18, 19) at ultrahigh resolution while scanning in each direction (16, 17), to form color swaths (Fig. 12) on a print medium (4A). The heads are at least partially aligned with respect to the longitudinal axis (85) of the medium, so that the swaths at least partly overlap (86) in that direction. An advance mechanism (31, 35) intermittently steps (42A) the print medium longitudinally, to enable displacement of successive swaths. A control system (15) alternates one full reciprocation (18, 19) of the heads, to discharge drops while scanning each way across the medium, with each step (42A) of the advance mechanism. Preferably the heads print, while scanning each way, a respective generally fixed nonzero fraction of the total amount of each secondary color (23 plus 24, or 23 plus 25, or 24 plus 25) to be printed. In this way the overall appearance of each secondary is essentially consistent and partway between two appearances respectively produced by scanning two ways. This invention avoids the long-print-zone drawbacks associated with full-height-staggered heads. Preferably the fractions for all the swaths are about equal, so that the consistent appearance for each secondary is essentially the average of two appearances respectively produced by scanning two ways. Various printmasks complete each swath in eight passes with four print-medium advances (Fig. 16), or four passes and two advances (Fig. 21), or two and one (Fig. 22) - in each case printing in every pass.
Inventors
- 👤 Josep Maria Serra
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 15:06
CPC Classifications
G; G06; G06K; G06K15/00; G06K15/02; G06K15/10; G06K15/102; G06K15/105; B; B41; B41J; B41J19/00; B41J19/14; B41J2/00; B41J2/005; B41J2/01; B41J2/21; B41J2/2132; H; H04; H04N; H04N1/00; H04N1/46; H04N1/50; H04N1/502; G06K2215/00; G06K2215/0082; G06K2215/0094
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
220 words
Apparatus for printing a color image on a printing
medium (4A); said apparatus comprising: bidirectional scanning printhead means (20, 20', 31,
35) for scanning bidirectionally across such printing
medium, to discharge color-ink droplets (18, 19) at ultrahigh
resolution while scanning in each direction (16, 17),
and thereby form swaths (Fig. 12) of such color image on
such printing medium in rows and columns (Fig. 15), said
rows being spaced apart by a pixel-row spacing (28); said printhead means including plural inkjet printheads
(20, 20', 23-26) to print plural colors respectively,
which plural printheads are mutually at least partially
aligned with respect to the longitudinal direction of
the printing medium; whereby the plural printheads print
respective color swaths (Fig. 12) which at least partially
overlap (79) in that longitudinal direction, and wherein
each printhead has nozzles (#1-#300) spaced apart at the
same spacing (28) as the pixel rows; printing-medium advance means (42) for intermittent
operation (42A) to move such printing medium longitudinally
to enable displacement, when desired, of successive
swaths (Fig. 12) along such medium; and control means (15) for alternating (A) one full
reciprocation (16-17) of the scanning printhead means, to
discharge color-ink droplets (18, 19) while scanning in
each direction (16,, 17) across such printing medium and
back, with (B) each operation (42A) of the printing-medium
advance means (42).
Claim 2
Dependent Claim
128 words
The apparatus of claim 1, wherein: the control means comprise means (20B) for operating
the printhead means (20, 20') to print, while scanning in
each direction (16, 17), a respective generally fixed
nonzero fraction of the amount of each secondary color (23
plus 24, or 23 plus 25, or 24 plus 25) to be printed in a
corresponding part of such image; and the overall color appearance for each secondary color
is substantially a consistent color appearance partway
between two color appearances respectively produced by
scanning in two directions; and preferably the respective generally fixed nonzero
fractions for all the swaths are generally equal, and said
consistent color appearance for each secondary color is
substantially an average of two color appearances respectively
produced by scanning in two directions.
Claim 3
Dependent Claim
172 words
The apparatus of claim 1, wherein: the control means (15) impose a constraint, as stated
below, in terms of a triad of control colors, said triad
being either: three color secondaries (23 plus 24, or 23 plus
25, or 24 plus 25), or three color primaries (23, 24, 25); the control means comprise means for operating the
printhead means to print: while scanning in a first direction (16) generally
all spots of two colors (for primaries
23, 24 or 23, 25 or 24, 25) of said triad
to be printed in each swath ( ), and while scanning in a second, opposite direction
(17), generally all spots of a third color
(for primaries 25, 24 or 23 respectively)
of said triad, and of black (26), to be
printed in each swath ( ); and each color of the triad is generally always deposited
during scanning in a respective fixed, consistent direction
( e. g. , 16 for 23); and the overall color appearance for each color of the
triad is substantially consistent.
Claim 4
Dependent Claim
59 words
The apparatus of claim 1, wherein: the control means comprise means for operating the
printhead means to complete each swath in eight passes,
with printing in each pass, and with four printing-medium
advances; and preferably the operating means provide best quality
of printing on vinyl, in which case preferably the operating
means impose an eight-by-eight "knight"-pattern (Fig.
16) printmask.
Claim 5
Dependent Claim
78 words
The apparatus of claim 1, wherein: the control means comprise means for operating the
printhead means to complete each swath in four passes,
with printing in each pass, and with two printing-medium
advances; and preferably the operating means provide normal quality
of printing on matte stock, in which case preferably the
operating means impose a four-by-four printmask (Fig. 21)
with the pattern: 2 1 4 3 4 3 2 1 1 2 3 4 3 4 1 2.
Claim 6
Dependent Claim
76 words
The apparatus of claim 1, wherein: the control means comprise means for operating the
printhead means to complete each swath in two passes,
with printing in each pass, and with one printing-medium
advance; and preferably the operating means provide fast printing
on matte stock, in which case preferably the operating
means impose a four-by-four printmask (Fig. 22) with the
pattern: 1 2 1 2 1 2 1 2 2 1 2 1 2 1 2 1.
Claim 7
Independent Claim
160 words
A method for printing a color image on a printing
medium (4A), using bidirectional scanning printhead means
(20, 20') comprising plural printheads (23-26) each with
nozzles (#1-#300) spaced apart at a nozzle spacing (28),
printing-medium advance means (31, 35), and control means
(15); said method comprising the steps of: scanning the printhead means bidirectionally (16, 17)
across the printing medium, to discharge (18, 19) color-ink
droplets at ultrahigh resolution while scanning in
each direction, and thereby form swaths (Fig. 12) of the
color image on the printing medium in a pixel grid of rows
and columns (Fig. 15), said rows being spaced apart by a
pixel-row spacing equal to said nozzle spacing (28); wherein said scanning step includes printing plural
bands of plural colors respectively, which plural bands
are mutually at least partially overlapping (Fig. 12) with
respect to the longitudinal direction (85) of the printing
medium; and intermittent operation (42A) of the printing-medium
advance means to semistagger the swaths.
Claim 8
Dependent Claim
91 words
The method of claim 7, wherein: the scanning step comprises operating (20B) the
printhead means (20, 20') to print, while scanning in each
direction (16, 17), a respective generally fixed nonzero
fraction of each secondary color (23 plus 24, or 23 plus
25, or 24 plus 25) to be printed in a corresponding part
of such image; and the overall color appearance for each pair of generally
adjacent spots of each secondary color is substantially
a consistent color appearance partway between two
color appearances respectively produced by scanning in two
directions.
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