Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2001-11-07
2003-09-30
Nguyen, Judy (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S093000
Reexamination Certificate
active
06626528
ABSTRACT:
This application is based on Patent Application No. 2000-348643 filed Nov. 15, 2000 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 print head and an ink jet printing apparatus using the same ink jet print head.
2. Description of the Related Art
There are various types of ink jet printing apparatus for performing printing on a printing medium by ejecting ink from an ink ejection opening and an ink jet print head used in the ink jet printing apparatus. Among these, typical examples of ink supply method to the ink jet print head include the following.
First, as a first type, there is a type in which using a tube from an ink vessel containing the ink, ink is supplied to the ink jet print head through a filter for preventing fine dust from coming in the ink jet print head, in this type, when ink in the ink vessel is exhausted, the ink vessel is replaced, and in this case, for preventing bubbles from mixing in the ink jet print head, it is general that ink is suction recovered or pressure recovered from the ink jet print head. Such an ink jet printing apparatus is often used in a large-sized ink jet printing apparatus.
Further, as a second other type, there is an ink jet printing apparatus using an on-carriage type ink jet cartridge of a structure integrally including an ink vessel and an ink jet print head. Such a type is often used in a relatively small-sized ink jet printing apparatus, which is widely used because replacement or the like of the ink jet print cartridge is simple. However, in such type of ink jet cartridge, when the ink vessel is replaced at the time the ink in the ink vessel is exhausted, because ink jet print head is wasted at the same time, recently, in view of running cost and environmental problems, various kinds of on-carriage type ink jet print cartridges are often proposed which allow replacement of only the ink vessel when the ink is exhausted.
The ink cartridge used in the second type ink jet printing apparatus is generally divided into an energy generation substrate for ejecting the ink, an ink jet print chip provided with an ink ejection opening corresponding to an energy generation element incorporated in the substrate, an ink jet print head portion provided with a filter for supplying ink not containing fine dust to the ink jet print chip, and an ink vessel portion for storing the ink, when the ink vessel is replaced, it is general that a suction recovery is performed for preventing air bubbles from coming into the ink jet print head which disturb stable printing.
However, even though the suction recovery is necessary when the ink vessel is replaced, if the suction recovery is performed many times, ink consumption other than for printing is increased which greatly increases the running cost. Further, for example, as one of general-purpose ones used as energy generation means for ejecting ink of the ink print head, an electrothermal converter (heater) is used. This is one which by energizing the heater, film boiling is generated in the ink so that the ink is ejected by the force. In this ink ejection process, dissolved air contained in the ink is generated as a gas even in small amount. If such a bubble builds up to a large amount, since it has an adverse effect on printing, before the bubble present in the ink jet print head becomes a size to have an adverse effect on printing, it is necessary to perform suction recovery of the ink jet print head. Also in this case, since ink consumption not used for printing occurs, there is a problem of an increased running cost.
In an ordinary ink jet print head, for example, as shown in
FIG. 6
, an ink jet print head
100
has a casing
102
integral with an ink vessel like an ink tank, this casing
102
forms an ink liquid chamber
103
, and a filter
104
is provided between the ink vessel. Further, in the casing
102
, at the opposite side to this filter
104
, an ink jet print chip portion
105
for ejecting ink to make printing is provided. The filter
104
is to remove impurities such as dust contained in the ink supplied from the ink vessel so that a clean ink is supplied into the ink liquid chamber
103
. Further, in the ink liquid chamber
103
, a sheet of plate member
106
is inclinedly provided, and a gap S is formed between the lower side end of the plate member
106
and the casing
102
. Therefore, as shown in the figure, the ink supplied into the ink liquid chamber
103
passes through the gap S between the end of the plate member
106
and the casing
102
to be supplied to the energy generation means for ejecting the ink and the ink jet print chip portion
105
provided with an ink ejection opening for ejecting the ink, so that the ink is ejected to a printing medium to perform printing.
Further, in such an ink jet print head
100
, a bubble collecting portion
108
is formed at the upper side end of the inclined plate member
106
, a ventilation hole
109
is provided in the casing
102
in the vicinity of the bubble collecting portion
108
, and the ventilation hole
109
is in general provided thereon with a hydrophobic film
110
of a porous material which has a property that air is passed but the ink is not passed so that the ink liquid chamber
103
and outer air are communicated through the hydrophobic film
110
with each other. However, if the ink liquid chamber
103
and outer air are only in a communication state, since ink in the ink liquid chamber evaporates, a bubble discharge portion
111
is provided which is constructed in a closed state that it is normally closed other than when bubbles accumulated in the bubble collecting portion
108
. Further, as the hydrophobic film
110
, a porous material such as “GOATEX” (tradename) or the like is used.
As shown in the figure, the bubble discharge portion
111
is formed of an enclosure
112
having an opening
113
, a lid for closing the opening
113
of the enclosure
112
, and a spring
115
for pressing the lid
114
. It is constructed so that bubble accumulated in such a bubble collecting portion
108
flows through the hydrophobic film
110
to the bubble discharge portion
111
to be accumulated in the bubble discharge portion
111
, bubble accumulated in the bubble discharge portion
111
, that is, air, is discharged to the outside.
As described above, in the prior art ink jet print head
100
constructed as shown in
FIG. 6
, the ink is supplied through the gap S towards the ink jet print chip portion
105
, and ejected from the ink jet print chip portion
105
to the printing medium to perform printing. In the ink jet print chip portion
105
in this case, a bubble B is generated by ink ejection, part of the generated bubble B moves through the gap S towards the filter
104
to be adhered to the filter
104
. Moreover, such a bubble B adhered to the filter
104
will never pass through the filter
104
due to a meniscus force of the filter
104
.
Therefore, in such a state, when bubble B further adheres to the filter
104
, bubble B accumulates at the lower side of the filter
104
, finally a malfunction occurs in ink supply from the ink vessel to the ink jet print chip portion
105
, making stable printing impossible.
It is therefore an object of the present invention, in order to solve such problems in the prior art, to provide a reliable ink jet print head and an ink jet printing apparatus using the ink jet print head which is possible to remove bubbles accumulated in the ink jet print head without unnecessary ink consumption by suction recovery and at a low running cost.
SUMMARY OF THE INVENTION
In accordance with the present invention which attains the above object, there is provided an ink jet print head for ejecting ink to make printing, wherein an ink liquid chamber between a filter and an ink ejection opening for ejecting the ink has means for collecting bubbles, means for moving bubbles to the bubble collecting means, and means for discharging bubbles accumulated in the bubble collecting means to t
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