Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1997-07-10
2001-02-06
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06183068
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 generation of bubble with application of thermal energy to the liquid, and to a head cartridge and a liquid discharging device incorporating the liquid discharging head. More particularly, the present invention relates to a liquid discharging head having movable members arranged to be displaced by utilizing generation of bubble, and to a head cartridge and a liquid discharging device incorporating the liquid discharging head.
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 bulletin of U.S. Pat. No. 4,723,129 etc., 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 path, Japanese Patent Application Laid-open No. 63-199972, for example, describes the flow path structure as shown in
FIGS. 38A and 38B
. The flow path structure and the head producing method described in the application 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
1012
). This back wave is known as loss energy, because it is not energy directed in the discharge direction.
The invention shown in
FIGS. 38A and 38B
discloses a valve
1010
located apart from a generation region of a bubble formed by a heat generating element
1002
and on the opposite side to the discharge opening
1011
with respect to the heat generating element
1002
.
In
FIG. 38B
, this valve
1010
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
1003
, and dropping into the flow path
1003
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
1010
.
However, as apparent from investigation on the case where a bubble is generated inside the flow path
1003
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
1010
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
1003
, as shown in
FIG. 38B
, the pressure directly related to discharge out of the bubble is already ready to discharge the liquid from the flow path
1003
. 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 discharge 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 discharge the discharge liquid thereby, for example as disclosed in Japanese Patent Application 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.
In the case of the head having the valve mechanism for preventing the back wave upon formation of bubble as in the conventional example shown in
FIGS. 38A and 38B
, however, while the discharge efficiency of liquid can be increased by the degree of prevention of the back wave transmitted to the upstream side, this structure prevents only escape of upstream-escaping components of the discharge force generated upon generation of bubble to the utmost, so that it is not always sufficient to achieve still larger increases of the discharge efficiency and the disch
Asakawa Yoshie
Ishinaga Hiroyuki
Kashino Toshio
Okazaki Takeshi
Barlow John
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Stephens Juanita
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