Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1998-05-05
2001-06-05
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S092000
Reexamination Certificate
active
06241350
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to an ink jet printing head and a printing apparatus using the same for effecting recording by ejecting ink onto a printing or recording material such as paper, cloth or the like. More particularly, it relates to an ink jet printing head and a printing apparatus using the same which is provided with a structure for suppressing vibration of ink generated during ink ejecting operation.
Heretofore, in a printing apparatus such as a printer, a copying machine, a facsimile machine or the like, an image comprising dot pattern is printed onto a recording material such as paper, plastic thin sheet or the like in accordance with image information.
The printing apparatus may be classified on the basis of the printing system into an ink jet type, a wire dot type, a thermal type, a laser beam type or the like. Among them, the ink jet type (ink jet printing apparatus) is such that ink (recording liquid) droplets are ejected through ejection outlets onto a printing material to effect the printing or recording.
Recently, a large number of printing apparatuses are used, to which high speed recording, high resolution, high image quality, low noise or the like are required. As a printing apparatus satisfying these requirements, the ink jet printing apparatus is noted. In the ink jet printing apparatus, the ink is ejected from the printing head, and therefore, the printing operation is carried out without contact to the printing material, and therefore, the print images are significantly stabilized.
However, because the ink jet type printing system uses ink which is liquid, it involves various hydrodynamical problems when the printing head is operated at a speed at or higher than the print limit speed. In addition, since the ink is liquid, the physical nature thereof such as viscosity or surface tension or the like, significantly changes due to the ambient temperature and the period in which it is not used, with the result that even if the printing operation is possible under a certain state, the printing operation is in some cases difficult due to the increase of the vacuum due to the reduction of the remaining amount of the ink in the ink container or due to the reduction of the ambient temperature.
As for the recording method, in many cases, an attempt is made to eject the ink through all of the ejection nozzles for as short period as possible to print a vertical line as rectilinearly as possible. In order to accomplish this, in most cases, several nozzles to 10 nozzles approx. of the several tens nozzles, are simultaneously actuated. If this is done, and if the operation is at the limit ejection frequency, the refilling of the ink into the ink passage delays with the result of the start of the next ink ejection operation before the refilling is completed. If this occurs, the improper ejection occurs. Or, the ejection amount extremely decreases. Particularly when a great number of nozzles are operated for a short period of time, the vacuum in a common liquid chamber is significantly increased tempolarily with the result of the delayed refilling action, or with the result of significant ink vibration due to resonance. If this occurs, the next ejecting operation might start while the ink is partly projected beyond the nozzle surface, with the result of the ink splashed.
SUMMARY OF THE INVENTION
Referring to
FIGS. 22-24
, the description will be made as to the problems resulting from such ink vibration on the basis of the investigations and findings of the inventors.
FIG. 22
illustrates a mechanism of generation of the ink vibration attributable to the ejection reaction pressure in the recording head. Designated by reference numerals
5
and
9
are an ink passage and a common liquid chamber communicating with the individual ink passages, respectively. Designated by
85
is an ink droplet ejected;
87
designates ejection reaction pressure produced by the ejecting action;
88
is the flow of the ink in the common liquid chamber toward the ink passages after ink ejection;
90
designates the ink flow toward the common liquid chamber.
In
FIG. 23
, a state of a meniscus
84
a
upon the start of the ink ejection is shown. In this Figure, a reference numeral
9
is a common liquid chamber;
83
a
is an ejection side surface;
81
is an ink passage;
3
is ejection energy generating element (heat generating resistor). In
FIG. 23
, (A). the meniscus is in good order. In
FIG. 23
, (B) shows the retracted meniscus immediately before the ink ejection timing. In
FIG. 14
, (C), the meniscus is projected due to the vibration. With (B) and (C) of
FIG. 23
, desirable ejections are not obtainable.
The consideration will be made as to the case in which all of the ejection nozzles are continuously actuated by the ejection heater
3
being actuated. The ink is first static in all of the portions in the ink jet cartridge. Then, the ejecting operations are started sequentially by block driving. At this time, the ink in the common liquid chamber
9
starts to refill into the nozzle
81
from the static state. Simultaneously, in the actuated nozzles, reverse flow indicated by
87
in
FIG. 22
is produced due to the reaction of the ejection with the complicated flow and vibrations. As a result, a relationship shown in
24
results between the meniscus retraction distance and the refilling period. Among all of the actuated nozzles, in the first half nozzles, the pressure level is high in the common liquid chamber due to the influence of the ejection reaction pressure wave, and therefore, the meniscus retraction is within a tolerable range. However, in the second half block, the first half nozzles start the refilling action with the result of high vacuum level, and therefore, a large meniscus retraction. Therefore, the refilling is delayed. The vibration acts as a trigger to produce vibration in the common liquid chamber. The cause of the vibration will be further analyzed.
There are three vibration generating mechanisms in the common liquid chamber. The first is the vibration due to the refilling motion for the individual nozzles, which mainly occurs in the common liquid chamber. The second is a high frequency vibration attributable to the crows talk between ink passages due to the phase difference in the ejection reaction pressure waves in the liquid passages when the nozzles are block-actuated. The third is low frequency vibration in the large inertia system including the supplying passage and the ink container. Actually, the three vibrations are overlaid, and appear as the meniscus position vibration.
The vibration in the common liquid chamber is determined by the refilling characteristic of the nozzle, as shown in FIG.
22
. This is a vibration determined on the basis of the inertia force when the ink is refilled into the nozzle, and is actually produced due to the ink motion between the nozzle and the ink in the liquid common chamber. The second vibration in the common liquid chamber is attributable to the block-drive. The wiring for driving the ejection energy generating element comprises segment wiring (seg) and common wiring (com), which are arranged in a matrix. As shown in
FIG. 24
, (A), the energy generating elements are supplied with the driving signals at the driving frequency (
1
/T) to effect the block drive. By the ejection reaction pressure wave in this case, the pressure in the common liquid chamber becomes temporarily positive. When the ejecting operation is carried out to the final block (com
8
), the negative pressure suddenly increases with the result of the delayed refilling speed for the respective nozzles. In
FIG. 24
, (B), the meniscus retraction (distance or amount) of the nozzle for each of the nozzles at the time of such a block drive, is shown relative to time.
In this Figure, a, b and c, represent the meniscus retractions of the nozzles driven in the first half in the ejection period T of all the blocks, in response to the signals com
1
,
2
and
3
. In this Figure, d shows the meniscus retraction in the fin
Arai Atsushi
Iwasaki Osamu
Nishikori Hitoshi
Otsuka Naoji
Takahashi Kiichiro
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Le N.
Nguyen Lamson D.
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