Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-10-22
2002-04-23
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06375303
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording head and an ink jet recording apparatus which perform recording by ejecting (discharging) an ink toward a record material. The invention is applicable to systems such as a word processor having a facsimile and printer section equipped with a printer, a copying machine and a communication system, which conducts the recording on record mediums such as paper, yarns, fibers, dishcloth, leather, metals, plastics, glasses and ceramics, and additionally applicable to an industrial recording apparatus involving a composite combination thereof with various types of processing units. In the invention, the “recording” signifies not only that meaningful images such as letters and figures are recorded on a record medium, but also that unmeaningful images such as patterns are recorded thereon.
2. Description of the Related Art
An ink jet recording apparatus is made to form an image of an ink dot pattern by supplying an ink to an ink jet recording head (which will be referred to hereinafter as a head) and by driving an ink droplet ejecting means such as a piezo device or an electrothermal converter, situated on the head, in accordance with image data.
In the case of color printing, a head is provided, for example, for each of yellow, Magenta, cyanogen and block inks, and in the case of a scanning type recording apparatus, these heads are mounted on a carriage which reciprocates along a record medium in predetermined directions. In a color recording apparatus, the heads for the respective colors are disposed in carriage moving directions (main scanning directions).
There is a problem which arises with the above-mentioned construction, however, in that the number of heads for the color recording increases so that the cost of the head unit increases and, additionally, so that the recording apparatus tends to increase in size.
FIG. 11
is a perspective view showing, as one example, a group of heads of a conventional ink jet color recording apparatus using inks different in density or consistency.
In this recording apparatus, a black (BK) ink head
311
BK, a first cyanogen (C
1
) ink head
311
C
1
, a second cyanogen (C
2
) ink head
311
C
2
, a first Magenta (M
1
) ink head
311
M
1
, a second Magenta (M
2
) ink head
311
M
2
and a yellow (Y) ink head
311
Y are arranged in parallel.
In the case of a head group having such a construction, since there is a need for the positional accuracy of adjacent nozzles of the heads to be set up on the order of microns, its manufacturing process becomes complicated, and additionally, installation of a head for each of ink colors leads to a relatively high head cost and makes difficult the size reduction of the head unit itself. Accordingly, the recording apparatus itself tends to increase in size and additionally to become costly.
In addition, since the plurality of heads are in a separated condition, there is a need to prepare, for each of the heads, an ink suction/pressurization receiving means for removing bubbles in the interiors of the nozzles or for recovering the ink from the increasing viscosity due to its being left for a long time.
One possible solution to these problems may be that a plurality of ink jet recording heads are formed integrally on the same substrate and disposed along the main scanning directions for conducting multivalued printing.
However, the point to be improved in the recording apparatus in which each of four color inks, namely, yellow, Magenta, cyanogen and block inks, existing in the main scanning directions has different densities is that four colors×two heads, namely, inks of eight colors., are necessary.
Meanwhile, it was found that yellow and block images are sufficiently expressible in color appearance through printing density or the like, and do not require variation of the ink density. On the other hand, the ink density has relatively great influence on color images based on Magenta and cyanogen in color appearance. Hence, a multivalued color recording apparatus using the needed minimum number of inks is desirable.
Accordingly, a recording apparatus can be designed such that one type is used as each of yellow and black inks and two types are taken as each of Magenta and cyanogen inks, that is, six color inks are put to use.
FIG. 12
is an illustration of one example in which nozzles for six colors are disposed separately in two heads.
In
FIG. 12
, a group of nozzles comprising a nozzle group
400
Y for ejecting an yellow ink, a nozzle group
400
M
1
for ejecting a first Magenta ink and a nozzle group
400
C
1
for ejecting a first cyanogen ink is formed in a recess section
357
made in a face
356
of an orifice plate
403
attached to a head
301
A.
In addition, a group of nozzles comprising a nozzle group
400
BK for ejecting a black ink, a nozzle group
400
M
2
for ejecting a second Magenta ink and a nozzle group
400
C
2
for ejecting a second cyanogen ink is formed in a recess section
357
made in a face
356
of an orifice plate
403
attached to a head
301
B. Still additionally, in the case of an apparatus employing different ink densities, since the dot formation order or time lag has influence when different inks are mixed to produce a secondary color, it is preferable that the different inks to be mixed are adjacent to each other in the main scanning directions of printing.
The disposition shown in
FIG. 12
, however, creates the following problems if two heads are disposed in the main scanning directions of printing.
That is, if the two heads are disposed in parallel as shown in
FIG. 12
, the yellow nozzle group and the black nozzle group assume an adjacent condition, and the two-color printing are required to be conduct simultaneously.
At this time, it was found that two types of inks interfere with each other on the record material to come to the boundary portion between images, that is, the so-called bleeding occurs, which degrades the print quality. Particularly, it can occur remarkably between yellow and black between which a great color difference exists.
Therefore, it is considered that nozzle groups discharging two different inks are disposed so as not to be adjacent to each other in the main scanning directions. That is, as shown in
FIG. 13
, a first nozzle of a nozzle group
200
M
1
of a head
301
A and a first nozzle of a nozzle group
200
M
2
thereof are placed on a line A—A.
However, in this case, a wasteful space
340
comes about in the head section so that the head itself increases in size to cause the size increase of the recording apparatus itself.
One possible solution to these problems would be that the wasteful space is removed from the head in
FIG. 13
as disclosed in Japanese Unexamined Patent Publication No. (HEI) 7-132619. That is, as shown in
FIG. 14
, the head
301
A and the head
301
B are disposed and density-different inks are used to enable high-quality multivalued color recording, and additionally, the nozzles of adjacent nozzle groups are disposed in a state shifted substantially by ½ of a nozzle pitch from each other in directions different from the main scanning directions to double the resolution for formation of a color image with a high gradation.
Furthermore, as shown in
FIG. 15
, the employment of a head
391
B having a nozzle group holding only a black ink can accomplish higher-speed printing of a black image. Additionally, in this case, by using a B section of a nozzle group of a head
391
for ejecting a black ink, a nozzle group
490
Y of a head
391
A for ejecting an yellow ink, a nozzle group
490
M thereof for ejecting a Magenta ink and a nozzle group
490
C thereof for ejecting a cyanogen ink, a color image is also printable.
Secondly, a description will be given hereinbelow of an orifice plate
403
with nozzle groups in the aforesaid heads.
FIG. 16
is a perspective view showing a conventional orifice plate
403
,
FIG. 17
is a cross-sectional view showing the orifice plate
403
, taken along a line B—B, and
FIG. 18
is a cr
Fukui Shigeki
Ishimatsu Shin
Sugimoto Hitoshi
Takenouchi Masanori
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Hsieh Shih-wen
Le N.
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