Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1997-06-09
2002-12-03
Brase, Sandra (Department: 2852)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06488365
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid discharging head for discharging desired liquid by generating a bubble formed by applying thermal energy to the liquid, and more particularly, it relates to a liquid discharging head having a movable member displaced by generating a bubble, a head cartridge having such a liquid discharging head, and a liquid discharging apparatus.
The present invention is applicable to recording apparatuses such as printers for effecting the recording on a recording medium such as a paper sheet, a thread sheet, a fiber sheet, a cloth, a leather sheet, a metal sheet, a plastic sheet, glass, wood, ceramic sheet and the like, copying machines, facsimiles having a communication system, and word processors having a printer portion, and to industrial recording apparatuses combined with various processing devices.
Incidentally, in this specification and claims, a term “recording” means not only application of a significant image such as a character or a figure onto a recording medium but also application of a meaningless image such as a pattern onto a recording medium.
2. Related Background Art
It is already known to provide an ink jet recording method, i.e., so-called bubble jet recording method in which change in state of ink including abrupt change in volume (generation of a bubble) is caused by applying energy such as heat to the ink and the ink is discharged from a discharge port by an acting force based on the change in state to adhere the ink onto a recording medium, thereby forming an image on the recording medium. As disclosed in U.S. Pat. No. 4,723,129, a recording apparatus using such a bubble jet recording method generally includes discharge ports for discharging ink, ink passages communicated with the discharge ports, and electrothermal converters as energy generating means disposed in the liquid passages and adapted to generate energy for discharging the ink.
According to such a recording method, a high quality image can be recorded at a high speed with less noise, and, in a head carrying out this method, since the discharge ports for discharging the ink can be arranged with high density, a recorded image having high resolving power and a color image can easily be obtained by a compact recording apparatus. Thus, recently, the bubble jet recording method has been applied to many office equipments such as printers, copying machines, facsimiles and the like, and is also applied to industrial systems such as print apparatuses.
As the application of the bubble jet technique to various field is increased, the following various requirements have recently been desired.
For example, regarding the requirement of improvement in energy efficiency, a heat generating element has been optimized by adjusting a thickness of a protection film. This method is effective in the point that transfer efficiency of generated heat to liquid is enhanced.
Further, in order to obtain a high quality image, there has been proposed a driving condition for providing a liquid discharging method capable of discharging the ink effectively at high speed due to stable bubble formation, and, in view of high speed recording, there has also been proposed the improvement in a liquid passage design to obtain a liquid discharging head in which liquid corresponding to discharged liquid can be refilled to the liquid passages quickly.
Among various liquid passage designs, a liquid passage structure as shown in
FIGS. 44A and 44B
is disclosed in the Japanese Patent Application Laid-Open No. 63-199972. The liquid passage structure and a head manufacturing method disclosed in the above Japanese Patent Application Laid-Open No. 63-199972 are inventions based on a back-wave (pressure directing toward a direction opposite to a direction to the discharge port, i.e., pressure directing toward a liquid chamber
12
) generated due to bubble generation. The back-wave is known as loss energy, since it is not directed toward the discharge port.
The invention shown in
FIGS. 44A and 44B
includes valves
10
spaced apart from bubble generating areas of heat generating elements
2
and disposed opposite to discharge ports
11
with respect to the heat generating elements
2
.
In
FIG. 44B
, the valve
10
has an initial position where a leaf of the valve is contacted with a ceiling of a liquid passage
3
, and, when the bubble is generated, the leaf of the valve is suspended into the liquid passage
3
. In this technique, the energy loss is suppressed by controlling a part of the back-wave by means of the valves
10
.
However, with the above-mentioned arrangement, as can be understood from the observation of the case where the bubble is generated in the liquid passage
3
containing the liquid to be discharged, suppression of the part of the back-wave is not practical to the discharging of the liquid.
As mentioned above, the back-wave itself does not relate to the liquid discharging directly. At the time when the back-wave is generated in the liquid passage
3
, as shown in
FIG. 44A
, a part of pressure of the bubble which directly relates to the liquid discharging already establishes a condition that the liquid can be discharged from the liquid passage
3
. Accordingly, it is apparent that, even when the part of the back-wave is suppressed, the suppression does not influence upon the liquid discharging greatly.
On the other hand, in the bubble jet recording method, since the heating of the heat generating element contacted with ink is repeated, ink deposit is accumulated on a surface of the heat generating element due to overheat of ink. Depending upon the kind of ink, a large amount of deposit is accumulated on the heat generating element, with the result that the generation of the bubble becomes unstable, thereby causing the poor ink discharging. Further, when the liquid to be discharged is easily deteriorated by heat or when liquid in which an adequate bubble is hard to be formed is used, it has been desired that the liquid to be discharged is not deteriorated and good liquid discharging is achieved.
In view of the above problems, there has been proposed a liquid discharging method wherein liquid (bubble liquid) in which a bubble is formed by heat is different from liquid (discharge liquid) which is to be discharged and the liquid is discharged by transmitting pressure generated by bubble formation to the discharge liquid, as disclosed in the Japanese Patent Application Laid-Open Nos. 61-69467 and 55-81172, and U.S. Pat. No. 4,480,259. In such a method, the discharge liquid (ink) is completely isolated from the bubble liquid by a flexible diaphragm made of silicone rubber and the like to prevent the discharge liquid from directly contacting with the heat generating elements and the pressure generated by the bubble formed in the bubble liquid is transmitted to the discharge liquid by deformation of the flexible diaphragm. With this arrangement, the deposit can be prevented from being accumulated on the heat generating elements and degree of freedom of selection of the discharge liquid can be increased.
However, in the arrangement in which the discharge liquid is completely isolated from the bubble liquid, since the pressure due to the formation of the bubble is transmitted to the discharge liquid by expansion/contraction deformation of the flexible diaphragm, the pressure of the bubble is greatly absorbed by flexible diaphragm. Further, since a deformation amount of the flexible diaphragm is not so great, although the advantage of separation between the discharge liquid and the bubble liquid can be obtained, energy efficiency and/or discharging ability may be worsened.
The present invention premises that fundamental discharging feature of a conventional method for discharging liquid by forming a bubble (particularly, bubble formed by film-boiling) in a liquid passage is improved to the extent that could not be considered by conventional techniques from the point of view which could not be supposed conventionally.
The premise is obtained by first t
Abe Tsutomu
Aono Kiyomi
Asakawa Yoshie
Ishinaga Hiroyuki
Karita Seiichiro
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