Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1997-07-07
2004-08-10
Lee, Susan S. Y. (Department: 2852)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S063000
Reexamination Certificate
active
06773092
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid discharging head for discharging a desired liquid by a novel discharge principle and, more particularly, to a liquid discharging head and a liquid discharging device having the structure for displacing a movable member by making use of generation of bubble.
The liquid discharging head of the present invention is the invention applicable to equipment such as a printer, a copying machine, a facsimile machine having a communication system, a word processor having a printer portion or the like, and an industrial recording device combined with one or more of various processing devices, with which recording is effected on a recording medium such as paper, thread, fiber, textile, leather, metal, plastic material, glass, wood, ceramic material, and so on.
It is noted here that “recording” in the present invention means not only provision of an image having meaning, such as characters or graphics, on a recorded medium, but also provision of an image having no meaning, such as patterns, on the medium.
2. Related Background Art
One of the conventionally known recording methods is an ink jet recording method for imparting energy of heat or the like to ink so as to cause a state change accompanied by a quick volume change of ink (generation of bubble), thereby discharging the ink through a discharge opening by acting force based on this state change, and depositing the ink on a recorded medium, thereby forming an image, which is so called as a bubble jet recording method. A recording apparatus using this bubble jet recording method is normally provided, as disclosed in the specification of U.S. Pat. No. 4,723,129, with discharge openings for discharging the ink, ink flow paths in communication with the respective discharge openings, and electrothermal transducers as energy generating means for discharging the ink located in the ink flow path.
The above recording method permits high-quality images to be recorded at high speed and with low noise and in addition, because a head for carrying out this recording method can have the discharge openings for discharging the ink as disposed in high density, it has many advantages; for example, high-resolution recorded images or even color images can be obtained readily by compact apparatus. Therefore, this bubble jet recording method is used in many office devices including printers, copiers, facsimile machines, and so on in recent years and further is becoming to be used for industrial systems such as textile printing apparatus.
With spread of use of the bubble jet technology in products in wide fields, a variety of demands described below are increasing these years.
For example, an example of investigation to meet the demand to improve the energy use efficiency is optimization of the heat generating member such as adjustment of the thickness of a protecting film. This technique is effective to an improvement in transfer efficiency of generated heat into the liquid.
In order to provide high-quality images, proposed were driving conditions for realizing the liquid discharge method or the like capable of performing good ink discharge based on high-speed discharge of ink and stable generation of bubble. From the standpoint of high-speed recording, proposed was an improvement in a configuration of flow path in order to obtain a liquid discharging head with high filling (refilling) speed into the liquid flow path of the liquid discharged.
Among this configuration of liquid passage, the publication of Japanese Patent Application Laid-open No. 63-199972, for example, describes the flow passage structure as shown in
FIGS. 22A and 22B
. The flow passage structure and the head producing method described in this publication are of the invention accomplished noting the back wave occurring with generation of bubble (i.e., the pressure directed in the opposite direction to the direction toward the discharge opening, which is the pressure directed to a liquid chamber
12
). This back wave is known as loss energy, because it is not energy directed in the discharge direction.
The invention shown in
FIGS. 22A and 22B
discloses a valve
10
located apart from a generation region of a bubble formed by a heat generating member
2
and on the opposite side to the discharge opening
11
with respect to the heat generating member
2
.
In
FIG. 22B
, this valve
10
is illustrated as being produced by the producing method making use of a plate material or the like, having an initial position where it is stuck to the ceiling of the flow path
3
, and dropping into the flow path
3
with generation of bubble. This invention is disclosed as the one for suppressing the energy losses by controlling a part of the aforementioned back wave by the valve
10
.
However, as apparent from investigation on the case where a bubble is generated inside the flow path
3
as retaining the liquid to be discharged in this structure, it is seen that to regulate the part of the back wave by the valve
10
is not practical for discharge of liquid.
The back wave itself originally has no direct relation with discharge, as discussed previously. At the point when the back wave appears in the flow path
3
, as shown in
FIG. 22B
, the pressure directly related to discharge out of the bubble is already ready to eject the liquid from the flow path
3
. It is thus clear that to regulate the back wave, more accurately, to regulate the part thereof, cannot give a great effect on discharge.
In the bubble jet recording method, on the other hand, heating is repeated while the heat generating member is in contact with the ink, which forms deposits due to scorching of ink on the surface of the heat generating member. A large amount of the deposits could be formed depending upon the type of ink, which could result in unstable generation of bubble and which could make it difficult to eject the ink in good order. It has been desired to achieve a method for well discharging the liquid without changing the property of the liquid to be discharged even if the liquid to be discharged is the one easily deteriorated by heat or even if the liquid is the one not easy to achieve adequate generation of bubble.
From this viewpoint, another proposal was made to provide a method to employ different types of liquids, a liquid (bubble generation liquid) for generating a bubble by heat and a liquid (discharge liquid) to be discharged, arranged to transmit the pressure upon generation of bubble to the discharge liquid and to eject the discharge liquid thereby, for example as disclosed in Japanese Patent Applications Laid-open No. 61-69467 and No. 55-81172, U.S. Pat. No. 4,480,259, and so on. In these publications, the ink as the discharge liquid is perfectly separated from the bubble generation liquid by a flexible film of silicone rubber or the like so as to keep the discharge liquid from directly contacting the heat generating member, and the pressure upon generation of bubble in the bubble generation liquid is transferred to the discharge liquid through deformation of the flexible film. By this structure, the method achieved prevention of the deposits on the surface of the heat generating member, an improvement in freedom of selection of the discharge liquid, and so on.
However, with the head of this structure in which the discharge liquid and the bubble generation liquid are completely separated from each other as described above, since the pressure upon bubble generation is transferred to the discharge liquid through the expansion/contraction deformation of the flexible film, the pressure by generation of bubble is absorbed to a quite high degree by the flexible film. In addition, the deformation of the flexible film is not so large, and therefore, the energy use efficiency and the discharge force could be degraded, though it is possible to achieve the effect by the separation of the discharge liquid from the bubble generation liquid.
The major subject of the present invention is to enhance the fundamental discharge characteristi
Asakawa Yoshie
Ishinaga Hiroyuki
Kashino Toshio
Kudo Kiyomitsu
Yoshihira Aya
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