Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-07-24
2002-11-26
Nguyen, Lamson (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S016000, C347S043000
Reexamination Certificate
active
06485125
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording method, and more particularly to the recording method by which while the recording head, having the dot forming element array in which N (N is a positive integer) dot forming elements are aligned at intervals of an even multiple of the distance d between dots in the recording resolution R in the secondary scanning direction which is the direction of conveyance of a recording material, is reciprocally moved in the primary scanning direction perpendicular to the secondary scanning direction, dots are formed on the recording material by the dot forming element array in accordance with recording data, and also the recording material is conveyed in the secondary direction and relatively to the recording head, thus performing recording. Also, the invention relates to a recording apparatus.
The present application is based on Japanese Patent Applications No. 2000-221965 and 2001-210857, which are incorporated herein by reference.
2. Description of the Related Art
In a recording apparatus, e.g., the ink jet printer for performing color printing, the recording head including a plurality of nozzles (dot forming elements) from which ink droplets are ejected, while being reciprocally moved in a primary scanning direction, ejects ink droplets, and also printing paper (a recording material) is conveyed relatively to the recording head and in the secondary scanning direction perpendicular to the primary scanning direction, whereby printing (recording) is performed.
On the recording head, the nozzle (dot forming element) arrays which eject the respective inks of black, dark cyan, light cyan, dark magenta, light magenta, and yellow are disposed in this order in the primary scanning direction.
As the recording method aimed at improving the recording quality of such a color ink jet printer, there is a recording method called the interlacing method described in U.S. Pat. No. 4,198,642 and Unexamined Japanese Patent Publication No. Sho. 53-2040.
In the printing by this “interlacing method”, while rasters are formed (i.e. printed) intermittently in the secondary scanning direction, an image is recorded. Then, adjacent rasters are bound to be formed by different nozzles.
However, when the conventional interlacing method is used for the bidirectional printing in which printing is performed on both the forward and backward trips in the primary scanning direction, after a certain raster is formed, the printing paper (recording material) is conveyed in the secondary scanning direction and relatively to the recording head, and thereafter the next raster is formed, whereupon the directions of movement of the recording head in both rasters are reversed to each other. Namely, a certain raster is formed on the forward trip in the primary scanning direction, whereas the next raster is formed on the backward trip in the primary scanning direction.
Therefore, in both rasters, the order of the nozzles from which ink droplets are ejected is reversed. Namely, for example, on the forward trip, ink droplets are ejected in the order of black, dark cyan, light cyan, dark magenta, light magenta, and yellow, whereas on the backward trip, ink droplets are ejected in the reverse order thereto of yellow, light magenta, dark magenta, light cyan, dark cyan, and black. Consequently, in every conveyance unit in the secondary scanning direction, striping (a kind of so-called banding) tends to be visibly generated.
In order to prevent such generation of striping, there is proposed the full-overlap recording method by which a plurality of dots constituting one raster are formed intermittently on each of the forward and backward trips. However, in this recording method, there is a problem that the respective rasters are formed on the forward and backward trips, so that printing speed (throughput) is reduced.
On the other hand, in the ink jet printer in which pigment is used as ink, the dot diameter formed by ink droplets tends to be smaller than that in case of using dye as ink. Consequently, the width (so-called line width) of the raster formed by aligning a plurality of dots in the primary scanning direction also tends to be narrower. Also, each nozzle normally has the deflection (so-called flying curve) peculiar to the nozzle, and ink droplets are not always ejected perpendicularly with respect to the recording head surface on which nozzles are disposed. In this flying curve, there are a flying curve in the secondary scanning direction and a flying curve in the primary scanning direction.
As in the interlacing method, when the adjacent rasters are printed by different nozzles, depending upon the degree of the flying curve in the secondary scanning direction of the nozzles, the gap (i.e. the so-called white stripe in which the ground of printing paper remains unprinted) which is not filled with ink droplets is sometimes produced between both rasters. For example, when a certain raster and the raster adjacent thereto are formed by the nozzles having the flying curves in the directions backing away from each other, the space between both rasters becomes wider than an ideal space, so that a white stripe is generated between both rasters.
Theoretically, if the dot diameter is set to the value (hereinafter referred to as a “theoretical value of dot diameter”) obtained by multiplying the interval d between dots by a square root of two, printing can be performed without a white stripe generated. On the other hand, in the actual ink jet printer, since the flying curve in the secondary scanning direction is present, in consideration thereof, the dot diameter is set to the order of twice as large as the interval d between dots, thereby preventing the generation of a white stripe.
In the conventional ink using dye, since the dot diameter becomes in the order of twice as large as the interval d between dots, even if any flying curve in the secondary scanning direction is present, there is no possibility that a white stripe is generated. On the other hand, in the pigment ink, although the dot diameter is larger than the theoretical value of dot diameter, it is smaller than twice the interval d between dots, so that depending upon the degree of the flying curve in the secondary scanning direction, there is a possibility that a white stripe is generated.
SUMMARY OF THE INVENTION
The invention is made in light of these circumstances, and its first object is to provide the recording method and the recording apparatus in which by improving the interlacing method, in the bidirectional recording, no striping is generated, and further, recording is possible at a higher speed than in the conventional full-overlap recording method.
Also, the invention has for its second object the arrangement that even in case the dot diameter becomes smaller as in the pigment ink, a so-called white stripe is not generated.
In order to attain the first object and a portion of the second object, the recording method according to a first aspect of the invention, in the recording method by which, while the recording head, having the dot forming element array in which N (N is a positive integer) dot forming elements are aligned at constant intervals D in the secondary scanning direction which is the direction of conveyance of a recording material, is reciprocally moved in the primary scanning direction perpendicular to the secondary scanning direction, dots are formed on the recording material by the dot forming element array in accordance with recording data, and the recording material is conveyed in the secondary direction and relatively to the recording head, is characterized in that the interval D is the value obtained by multiplying the interval d between dots in the recording resolution in the secondary scanning direction by an even number k, and also the even number k and the dot forming element number N are in prime relation to each other, that there are included a first step of forming dots on the recording material by the dot forming element array while moving the
Fujioka Satoshi
Hayashi Toshihiro
Nguyen Lamson
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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