Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1997-07-09
2003-02-25
Fuller, Benjamin R. (Department: 2855)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06523941
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid discharging method to discharge the required amount of a liquid by the bubble generated by applying the thermal energy to the liquid as well as a liquid discharging head, a head cartridge and a liquid discharging device.
2. Related Background Art
A conventional ink jet recording method, so-called a bubble jet recording method is well known which causes the status change of ink with sudden volume change (bubble generation) by applying such pulse energy as heat pulse etc., to ink according to a signal to be recorded to discharge ink from an ink discharging port by a pressure caused by such status change in order to apply ink onto a record medium. As disclosed in U.S. Pat. No. 4,723,129, a recording device using the above-mentioned bubble jet recording method generally comprises an ink discharging port, an ink flow path connected with such ink discharging port, an electrothermal converting element as a means for generating energy to discharge ink provided in the ink flow path.
It is possible to record an image of high quality at a high speed with low noise by this recording method. At the same time, the ink discharging ports can be arranged in high density on a recording head for such recording method. Therefore, the bubble jet recording method has many advantages. For example, an image of high resolution and even a color image can be recorded by means of a compact equipment. For this reason, the bubble jet recording method has been recently applied not only to various kinds of office apparatus such as a printer, a copying machine, and a facsimile, but also to industrial systems such as a textile printing machine.
With the diffusion of bubble jet technology into various fields as described above, in recent years, the following developments have been made:
For example, a heat generating element has been optimized by adjusting the thickness of a protective film to improve energy efficiency. This improvement is effective to enhance the heat transfer efficiency to a liquid such as ink. On the other hand, a driving condition for discharging a liquid such as ink properly at a high speed with stable bubble generation to obtain a high quality image has been proposed. An improved flow path shape has also been proposed to obtain a liquid discharging head with high refilling speed to fill a liquid flow path with a liquid after a liquid discharging process in order to achieve high speed recording.
Various flow path shapes have been proposed, as described above. Japanese Patent Application Laid-Open No. 63-199972 discloses a flow path construction shown in
FIGS. 36A and 36B
. The invention disclosed in the patent is the flow path construction and head manufacturing process based on back wave due to bubble generation (a pressure in a direction opposite to a liquid discharging port, that is, a pressure toward a liquid chamber
12
). The back wave is known as an opposite energy because it is not the energy in the liquid discharging direction.
In the case of the flow path construction shown in
FIGS. 36A and 36B
, a valve
10
is installed at a location on a side opposite to the liquid discharging port
11
with respect to the heat generating element
2
, apart from the bubble generating region of the heat generating element. The valve
10
is manufactured from a plate, etc. As shown in
FIG. 36B
, it has an initial position on the ceiling of the flow path
3
. When the bubble generates, it droops into the flow path
3
. In the case of the invention shown
FIGS. 36A and 36B
, the valve
10
controls part of the back wave to check the movement of the back wave toward an upstream side. As a result, an energy loss is controlled. However, the careful examination of the bubble generating process reveals that the control of part of the back wave by the valve
10
installed in the flow path
3
containing a liquid to be discharged is not preferable for the liquid discharging process. That is, originally, the back wave itself does not have a direct influence on the liquid discharging process as described above. When the back wave generates in the flow path
3
, as shown in
FIG. 36A
, a pressure having a direct influence on the liquid discharging process can discharge a liquid from the flow path
3
. Therefore, the control of the back wave, especially the control of part of the back wave does not have a great influence on the liquid discharging process.
On the other hand, in the case of the bubble jet recording method, due to the repetition of the heating process under the condition that the heat generating element is in contact with ink, burned ink may accumulate on the surface of the heat generating element. Some kind of ink leaves much burned ink and results in unstable bubble generation. As a result, smooth ink discharge is not guaranteed. Therefore, the development of a process to discharge a liquid smoothly without denaturing it has been eagerly waited, even through a liquid to be discharged is apt to deteriorate and even though such liquid does not generate sufficient bubble.
Japanese Patent Application Laid-Open Nos. 61-69467, 55-81172 and U.S. Pat. No. 4,480,259, etc., disclose a process in which two kinds of liquid, namely, a bubble-generating liquid and a liquid to be discharged (a discharging liquid) are employed separately to discharge the latter by giving the bubble pressure to the latter. In the case of these inventions, ink, the liquid to be discharged is completely separated from the bubbling liquid by means of a flexible membrane made of silicone rubber, etc. so that the former does not come into contact with the latter, and at the same time the pressure due to bubble generation is transmitted to the liquid to be discharged by the displacement of the flexible membrane. By such configuration, the accumulation of burned liquid on the surface of the heat generating element can be prevented and the liquid to be discharged can be more freely selected.
However, in the case of the above-mentioned head configuration in which the liquid to be discharged is completely separated from the bubbling liquid, the pressure due to bubble generation is transmitted to the liquid to be discharged by the expansion/contraction and the displacement of the flexible membrane, so the considerable portion of such pressure is absorbed by such membrane. In addition, the flexible membrane does not displace much, so an advantage due to the separation of the liquid to be discharged from the bubbling liquid can be obtained, but the energy efficiency and the liquid discharging pressure may lower.
Some inventors of the present invention made the following analyses to provide a novel liquid discharging method using the bubble as well as a head, etc. for such method based on the principle of a liquid droplet discharging process: the first technical analysis to analyze the principle of the mechanism of a movable member in a flow path based on its behavior; the second analysis to analyze the principle of the droplet discharge by the bubble pressure; the third analysis to analyze the bubble generating region of a heat generating element. As a result, it becomes possible to improve the basic discharging properties of the liquid discharging method by the bubble (the bubble due to film boiling) generated in the flow path to such high level not expected from the conventional viewpoint.
The present applicant has established an entirely novel method for controlling the bubble actively by arranging the fulcrum of the movable member on the upstream side and its free end on the discharging port side, namely, on the downstream side, and at the same time by arranging the movable member itself in the heat generating element area or the bubble generating area based on the results of the above-mentioned analyses. The present applicant has applied such method to be patented. More particularly, it was found out that the bubble discharging properties could be greatly improved by the growing portion of the bubble generated in the downstream side, t
Asakawa Yoshie
Ishinaga Hiroyuki
Kashino Toshio
Kudo Kiyomitsu
Yoshihira Aya
Dickens C.
Fuller Benjamin R.
LandOfFree
Liquid discharging method and liquid discharging head does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Liquid discharging method and liquid discharging head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Liquid discharging method and liquid discharging head will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3162254