Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-02-13
2002-08-20
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S067000
Reexamination Certificate
active
06435670
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid discharge head to discharge a liquid by generating a bubble by acting a thermal energy to the liquid, a liquid discharge method using the liquid discharge head, a recovery method, a liquid discharge apparatus, and a fluid structure body.
The present invention is applicable to an apparatus such as a printer to carry out recording to a recording medium such as a paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, and ceramic, copier, facsimile having a communication system, and word processor having a printer part and an industrial recording apparatus in composite combination with various processing apparatus.
For reference, “recording” in the present invention means not only attaching an image such as a character and a figure having a meaning to the recording medium, but also attaching the image such as a pattern without any meaning.
2. Related Background Art
Conventionally, in a recording apparatus such as printer, an ink jet recording method, namely, so-called bubble jet recording method, in which such energy as heat is applied to a liquid ink in a flow path to generate the bubble and the ink is discharged from a discharge port by an action force caused by an acute volume change according to generation of the bubble to form the image by attaching this to the recording medium, has been known. In the recording apparatus using the bubble jet recording method, as disclosed in U.S. Pat. No. 4,723,129, the discharge port to discharge the ink, the flow path communicating with the discharge port, and an electrothermal converting element as energy generating means to discharge the ink flown in the flow path is generally arranged.
According to such recording method, a high quality image can be recorded in a high speed and with a low noise and also in the head to do this recording method, the discharge port to discharge the ink can be arranged in a high density and thus, there are many advantageous points in which a small apparatus can easily yield the recorded image of a high resolution and a color image. Therefore, the bubble jet recording method is recently applied to many office instruments such as printer, copier, and facsimile and besides, applied to the industrial systems such as textile printing apparatus.
As described above, as the bubble jet technology is increasingly applied to products of many fields, various kinds of requirements have increased. For example, in order to obtain the high quality image, a driving condition was proposed to present the liquid discharge method capable of better ink discharge with a high speed ink discharge and a stable bubble generation and in view of high speed recording, an improved shape of flow path was proposed to realize the liquid discharge head with the high speed to refill the discharged liquid in the liquid flow path.
Among them, in the head to generate the bubble in a nozzle to discharge the liquid according to growth of the bubble, bubble growth toward an opposite direction of the discharge port and a liquid flow caused thereby have been known as factors to lower a discharge energy efficiency and a refilling characteristic. An invention of a structure to improve such discharge energy efficiency and refilling characteristic was proposed in European Patent Application Laid-Open No. EP0436047A1.
In the invention described in the publication, a first valve put between an area around the discharge port and a bubble generating part to shut these and a second valve put between the bubble generating part and an ink supply part to shut these completely are alternately opened and closed (
FIG. 4
to
FIG. 9
of EP436047A1). For example, in
FIG. 7
of the publication, as shown in
FIG. 133
, a heat generating body
110
is installed in almost center of the ink flow path
112
between an ink vessel
116
on a substrate
125
forming an internal wall of the ink flow path
112
and a nozzle
115
. The heat generating body
110
is located in a section
120
, of which circumference is all closed, inside the ink flow path
112
. The ink flow path
112
is configured by the substrate
125
, thin films
123
and
126
, directly layered on the substrate
125
, and tongue piece
113
and
130
as closing bodies. Tongue piece released are shown by a broken line in FIG.
133
. Another thin film
123
extending in a plane parallel to the substrate
125
and ending at a stopper
124
covers over the ink flow path
112
. When the bubble occurs in the ink, a free end of the tongue piece
130
, in the area of the nozzle, closely contacting with the stopper
126
in a static status is displaced upward and an ink liquid is ejected from the section
120
to the ink flow path
112
subsequently through the nozzle
115
. Here, the tongue piece
113
installed in the area of the ink vessel
116
closely contacts with the stopper
124
in the static status and thus, the ink liquid in the section
120
does not go to an ink layer
116
. When the bubble in the ink disappears, the tongue piece
130
is displaced downward to contact closely again with the stopper
126
. And, the tongue piece
113
falls down in the section
120
and hence, the ink liquid flows in the section
120
.
SUMMARY OF THE INVENTION
However, in the invention described in EP436047A1, three chambers of the area around the discharge port, the bubble generating part, and the ink supply part are divided in two parts and therefore, in discharge, the ink following a liquid droplet largely tails resulting in a considerable amount of a satellite dots in comparison with a normal discharge system, in which growing, shrinking, and disappearing of a bubble take place (it is presumed that an effect of retreat of a meniscus caused by disappearance of the bubble cannot be employed). On the other hand, a valve in the discharge port side for the bubble causes a great loss of discharge energy. In addition, in replenishment (refilling the ink in the nozzle), the liquid is supplied to the bubble generating part in accordance with disappearance of the bubble. However, the liquid cannot be supplied to the area around the discharge port until the next bubbling occurs and hence, not only a size variation of the liquid droplets discharged is large, but also a frequency responding to discharge is very high and therefore it is not practical.
The present invention proposes the invention to improve a suppressing efficiency of a component to grow a bubble toward a direction opposite to the discharge port and also, on the contrary thereto, improve a discharge efficiency on the basis of a new idea to find out an innovative method and head constitution to realize a high efficiency of the refilling characteristic.
The present inventors, as a result of an intensive research, found that in a nozzle structure of the liquid discharge head, by which a bubble is generated in the nozzle formed linearly and the liquid is discharged according to growth of the bubble, a function of a special check valve allows suppressing bubble growth in the direction opposite (backward) to the discharge port and an effective use of the backward discharge energy for the discharge port side. Furthermore, the present inventors also found that the function of the special check valve allows suppressing a backward bubble growth component and realizing an effective refilling characteristic to make the frequency responding to discharge very high.
Consequently, an object of the present invention is to realize both improvement of a discharge power and improvement of discharge frequency by the nozzle structure and the discharge method using a new valve function and to establish a new discharge system (structure) to achieve the head of the high speed and high image quality of a level, which has not been achieved so far.
To achieve the above described object, the liquid discharge head according to the present invention is characterized by having a plurality of discharge ports to discharge a liquid, a plurality of liquid flow paths, in which an end part is pe
Inoue Ryoji
Kubota Masahiko
Kudo Kiyomitsu
Takenouchi Masanori
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