Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2002-02-05
2004-07-20
Nguyen, Lamson (Department: 2861)
Incremental printing of symbolic information
Ink jet
Controller
C347S041000, C347S037000
Reexamination Certificate
active
06764154
ABSTRACT:
This application is based on Patent Application No. 2001-30186 filed Feb. 6, 2001 in Japan, the content of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink-jet printing apparatus of a so-called serial scan type and a method for performing ink-jet printing using such an apparatus.
2. Description of the Related Art
An ink-jet printing apparatus prints an image on a printing medium such as a sheet of paper or a thin plastic sheet by ejecting ink from an ink-jet printing head onto the surface of the printing medium, fixing the ink, and imparting color thereto. A multi-color image can be obtained using a plurality of color inks, such as cyan (C), magenta (M), yellow (Y), and black (Bk). In this case, for example, a typical ink-jet printing head has a plurality of nozzle rows corresponding to their respective color inks, so that the multi-color image can be printed on the printing medium by ejecting ink for each of colors from the nozzle rows (hereinafter, also referred to as nozzle array) onto the printing medium as needed.
For preventing ink from blotting on the image printed on the printing medium (e.g., a sheet of paper), ink with a comparatively high permeability is often used as ink of each color except black. Also, ink with comparatively low permeability is often used as a black ink for the printing of a character image because it is capable of printing the edge of the character image sharply. If the black ink with a high permeability is used, on the other hand, the edge of the character becomes jagged. In other words, when the black ink touches on the surface of the paper, the black ink may move along fibers of the paper such that it sinks into the paper quickly compared with other color inks.
For an ink-jet printing system, from above point of view, it is usual to use an ink composition with comparatively low permeability as a black ink and an ink composition with comparatively high permeability as each of color inks. In such an ink-jet printing system, the blotting of ink may be caused on the boundary between a black image (i.e., an image formed by ink of black) and the color image (i.e., an image formed by at least one color ink except black) when the black ink and the other color inks make contact with each other on the printing medium. Hereinafter, such a blotting of ink will be referred to as “a black-color blotting”.
For avoiding or relieving the problem to be caused by the blotting of ink on the printing medium, as shown in
FIG. 7
, there is a method of arranging nozzle rows of a printing head in a serial scan type ink-jet printing apparatus. Such a printing apparatus sequentially performs the image formation on a printing medium by repeating a scanning of the printing head in the main-scan direction and a transfer of the printing medium in the sub-scan direction perpendicular to the main-scan direction. When the printing head is scanning, ink is ejected from nozzles arranged on the printing head.
Referring now to
FIG. 7
, there is shown an ink-jet printing head H provided with the ink-jet printing apparatus. The printing head H has several nozzle rows arranged in parallel on the surface thereof. Each nozzle row consists of a series of nozzles and extends in the direction Y for transferring a printing medium P (i.e., the sub-scan direction Y). These nozzle rows include: a nozzle row Bk for ejecting ink of black; a set of nozzle rows C
1
and C
2
for ejecting ink of cyan; a set of nozzle rows M
1
and M
2
for ejecting ink of magenta, and a set of nozzle rows Y
1
and Y
2
for ejecting ink of yellow. In the figure, the arrow X
1
indicates the forward movement of the printing head H in the main-scan direction, while the arrow X
2
indicates the backward movement thereof. In this conventional example, the printing head H is able to perform printing movements in both directions X
1
, X
2
(i.e., bi-directional printing movement). If the printing head H scans in the forward direction X
1
, for example, it is allowed to perform the printing movement by ejecting ink from nozzle rows C
1
, M
1
, and Y
1
, respectively (i.e., the forward printing movement). If the printing head H scans in the backward direction X
2
, on the other hand, it is allowed to perform the printing movement by ejecting ink from nozzle rows C
2
, M
2
, and Y
2
, respectively (i.e., the backward printing movement). In these forward and backward printing movements, it is possible to eject black ink from the nozzle rows Bk as needed.
In the case of printing an image using only black ink, nozzles arranged on the entire length “A” of the black nozzle row Bk can be used. As shown in
FIG. 7
, the nozzle row Bk is designed to be longer than other nozzle rows C
1
, C
2
, M
1
, M
2
, Y
1
, and Y
2
, so that an area of the printing medium on which an image can be printed by the nozzle row Bk per one scanning movement of the printing head H (hereinafter, such an area is referred to as a printing area) can be larger than a printing area on which an image is printed by at least one of other nozzle rows C
1
, C
2
, M
1
, M
2
, Y
1
, and Y
2
. Therefore, a high-speed printing of a mono-color image only with black ink can be realized.
In the case of printing a multi-color image, a part “a” of the nozzle row Bk is used. In this case, in addition, a part “b” (with a length equal to the part “a”) of each of the nozzle rows C
1
, C
2
, M
1
, M
2
, Y
1
, and Y
2
is also used. First, the printing medium P is moved to the position [
1
] and then the printing head H is moved in the direction X
1
while ejecting black ink from the part “a” of the nozzle row Bk depending on an image to be printed (hereinafter, referred to as a printing image). As a result, the image is printed on an area S
1
on the printing medium P. Subsequently, the printing medium P is moved from the position [
1
] to the position [
2
]. In this case, the position [
2
] is apart from the position [
1
] at a distance corresponding to the length of the part “a” in the sub-scan direction Y. Then, the printing head H is moved in the direction X
2
while ejecting cyan ink, magenta ink, and yellow ink from the respective parts “b” of the nozzle rows C
2
, M
2
, and Y
2
(hereinafter, these inks are collectively referred to as “color inks”) to complete the formation of a multi-color image on the area S
1
on the printing medium P. During the period of moving the printing head H in the direction X
2
, an additional image formation is performed on a next area S
2
on the printing medium P by ejecting black ink from the part “a” of the nozzle row Bk depending on the printing image. Subsequently, the location of the printing medium P is shifted to the position [
3
] apart from the position [
2
] by the length of the part “a” in the sub-scan direction Y. Then, the printing head H is moved in the direction X
1
while ejecting color inks from the respective parts “b” of the nozzle rows C
2
, M
2
, and Y
2
to complete the formation of a multi-color image on the area S
2
on the printing medium P. During the period of moving the printing head H in the direction X
1
, an additional image formation is performed on a next area S
3
on the printing medium P by ejecting black ink from the part “a” of the nozzle row Bk depending on the printing image.
In such a printing method, the black ink is applied on the predetermined area of the printing medium P at first and then the color inks are applied on the same area during the next scanning movement of the printing head H. Therefore, a pass time between a performing time of the printing by the black ink and a performing time of the printing by the color inks is long. Consequently, it is preferable to prevent ink from blotting on the printing medium P, compared with the case of applying black and color inks on the printing medium P during the same scanning movement of the printing head H. In other words, the above method allows the decrease in the black-color blotting
Chikuma Toshiyuki
Iwasaki Osamu
Nishikori Hitoshi
Otsuka Naoji
Sugimoto Hitoshi
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