Incremental printing of symbolic information – Ink jet – Controller
Reexamination Certificate
2001-07-09
2002-10-29
Nghiem, Michael (Department: 2853)
Incremental printing of symbolic information
Ink jet
Controller
Reexamination Certificate
active
06471326
ABSTRACT:
This application is based on patent application Ser. No. 239,773/1997 filed on Sep. 4, 1997 in Japan and No. 246,890/1997 filed on Sep. 11, 1997 in Japan, the content of which is incorporated by reference.
BACKGROUND OF THE INVENTION
1. Filed of the Invention
The present invention relates to an ink-jet head and an ink-jet printing apparatus performing printing by ejecting an ink droplet toward a printing medium.
2. Description of the Related Art
As an ink-jet head, there is a head which instantly causes bubbling in ink by thermal energy supplied from a heater to perform printing by ejecting the ink with growth of the bubble. Such head is particularly superior in high speed printing and high density printing. In such head, the head employing a system, in which the bubble of the ink generated on the heater is communicated with the atmosphere, has been known (Japanese Patent Application Laid-open No. 10940/1992, Japanese Patent Application Laid-open No. 10941/1992, Japanese Patent Application Laid-open No. 10942/1992 and so on). The first feature of the head of this type is high ink ejection speed and high reliability. The second feature of the head of this type is that substantially all of the ink between the heater and the ejection opening can be ejected to make volumes of the ejected ink through all ejection openings substantially constant to make density fluctuation small.
According to progress of printing technology, it has been required to print smaller ink droplets with higher density. However, to make the ink droplet smaller, an ink passage becomes thinner which tends to cause lowering of ejection efficiency namely lowering of ejection speed. Therefore, problems of the reliability, such as unstability of the direction of ink ejection, unstability of ink ejection caused by increasing of the viscosity of the ink due to evaporating of the volatile component in the ink during the head resting, are caused. In this respect, the head of the type set forth above, namely the head, in which the bubble is communicated with the atmosphere, is difficult to cause the foregoing problems and can be adapted to demand for high quality printing in the future.
However, in the head of the type set forth above, the following problems are encountered. Namely, since the bubble is communicated to the atmosphere during growth of the bubble, the bubble becomes large meniscus upon communication with the atmosphere to make a re-fill time of the ink long. When next bubbling is caused without waiting for completion of re-filling, in certain case, the ink cannot form normal droplet and to cause so-called mist phenomena, in which the ink becomes a mist state, and the ink may fly in various direction to stain the printing medium.
On the other hand, conventionally, as an output means of a personal computer and so on, printers of various printing types are employed. According to speeding up of process speed of the personal computer, spreading of internet, demand for speeding up of a color image printing is increasing. Therefore, an ink-jet printer which can perform high speed printing comparable with a laser printer, can be easily adapted for color printing, and is low cost, has been widely used.
One of typical printing system of the ink-jet printers is a bubble-jet printing system which is a system heating and evaporating the ink by a thermal energy generating means and ejecting the ink droplet through the ejection opening by a pressure of the bubble generated. After ejection of the ink droplet, the vapor of the ink within the bubble is condensed to return into a liquid state to finally extinguish the bubble. While the ink in the ink passage is reduced by ejection of the ink, the ink is filled through an ink supply passage.
FIG. 15
is an explanatory illustration showing a construction of a head of a bubble-jet printing system associated with the background art. A plurality of ink passages
22
are branched from the ink supply passage
21
. Thus, the ink passages
22
and the ink supply passage
21
are communicated with each other. On a tip end of each ink passage
22
, an ejection opening
23
for the ink droplet is provided. In opposition to each ejection opening
23
, a heater
24
(see
FIG. 17
) as a thermal energy generating means is provided. On the other hand, by slightly differentiating lengths of respective ink passages
22
(distance from the branching position
25
from the ink supply passage
21
to the ejection opening
23
) instead of making them uniform, the positions of the ejection openings
23
are offset to permit high density printing. Since the center of the ejection opening
23
and the center of the heater
24
are located in opposition, the distance from the branching position
25
from to the ejection opening
23
is consistent with a distance (hereinafter referred to as “distance C-H”) from the branching position
25
to the heater
24
.
In the shown example, two hundreds fifty-six ink passages
22
are provided, in total. However, in
FIG. 15
, only thirty-two ink passages
22
are shown. These ink passages
22
are divided into two sets, i.e. even number passages located on the left side in the drawing and odd number passages located on the right side. In each set, the ink passages are grouped per eight into sixteen groups. The heaters
24
of eight ink passages
22
in the same group are driven simultaneously in time division so that sixteen times driving in total of heaters is set at one cycle. It should be noted that lengths of the ink passages
22
(distances from the branching position
25
to the ejection opening
23
) are divided into five kinds.
Discussing this example, concerning the passages in the even number order in sequence (hereinafter referred to as “even number passages”), eight passages Seg
0
,
32
,
64
,
96
,
128
, . . .
224
constitute a first group. Eight passages Seg
10
,
42
,
74
, . . .
234
constitute a second group. Eight passages Seg
20
,
52
, . . .
244
constitute a third group. Eight passages Seg
30
,
62
, . . .
254
constitute a fourth group. Eight passages Seg
8
,
40
, . . .
232
constitute a fifth group. Eight passages Seg
18
,
50
, . . .
242
constitute a sixth group. Eight passages Seg
28
,
60
, . . .
252
constitute a seventh group. Eight passages Seg
6
,
38
, . . .
230
constitute a eighth group. Eight passages Seg
16
,
48
, . . .
240
constitute a ninth group. Eight passages Seg
26
,
58
, . . .
250
constitute a tenth group. Eight passages Seg
4
,
36
, . . .
228
constitute a eleventh group. Eight passages Seg
14
,
46
. . .
238
constitute a twelfth group. Eight passages Seg
24
,
56
, . . .
248
constitute a thirteenth group. Eight passages Seg
2
,
34
, . . .
226
constitute a fourteenth group. Eight passages Seg
12
,
44
,
236
constitute a fifteenth group. Eight passages Seg
22
,
54
, . . .
246
constitute a sixteenth group. As can be seen from the above, grouping of the ink passages are done by grouping every sixteen passages.
Also, the passages in the odd number order in sequence (hereinafter referred to as “odd number passages”), similarly to the even number passages, the passages are grouped into sixteen groups, such that eight passages Seg
1
,
33
,
65
,
97
,
129
, . . .
225
constitute a first group, eight passages Seg
11
,
43
,
75
, . . .
235
constitute a second group, eight passages Seg
21
,
53
, . . .
245
constitute a third group, . . . eight passages Seg
23
,
55
, . . .
247
constitute a sixteenth group. Accordingly, each group is consisted of eight even number passages and eight odd number passages and thus is consisted of sixteen passages in total.
Upon printing, the first group to the sixteenth group are driven per group in sequential order. An interval after driving one group to drive the next group is 5.9 &mgr;sec.
In case of
FIG. 15
, the even number passages are driven to eject the ink droplet in a sequential order from the passage having short distance C-H, and the odd number passages are driven to eject the ink droplet in a sequential order from the passage having long di
Mizutani Michinari
Tachihara Masayoshi
Nghiem Michael
Stewart Jr. Charles W.
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