Patent Application
20090201352
This application claims benefit of priority under 35 USC 119 based on Japanese Patent Application P2008-27526, filed Feb. 7, 2008,the entire contents of which are incorporated by reference herein.
1. Field of the Invention
The present invention relates to an ink jet system and a method for removing an air bubble from the inside of an ink jet nozzle.
2. Description of the Related Art
An ink jet printing method is used for spraying fine droplets of ink directly onto a printing medium, so as to print indicia thereon. The ink can be sprayed onto the print medium by use of a simple mechanism, and therefore, the method can be utilized in various fields. For example, in the field of semiconductor technology, an ink jet print system has become a focus of attention as a technique for forming a pattern on a liquid crystal.
In the case where a pattern is formed on a liquid crystal by the resist, many processes are required, including mounting a cap on the liquid crystal, followed by etching, and the like. In contrast, when ink is applied by an ink jet device, the pattern can be formed directly on a liquid crystal substrate without either a cap mounting process or an etching process. As a consequence, the processes can be simplified and the amount of organic solvent can be reduced. Thus, a method of applying ink using an ink jet device has becomes a focus of attention in the field of semiconductor technology.
In this case, in order to form a high density pattern, ink needs to be sprayed in a fine pitch. However, if an air bubble adheres to a nozzle side surface of a nozzle plate in the ink jet device, the ink cannot flow straight, thereby making it difficult to apply the ink in a fine pitch.
One way of solving the above-described problem, for example, is to introduce gas to flow into an ink supply tank containing the ink before use of the ink, followed by degassing, so as to inhibit the gas from intruding into the nozzle. However, gas contained in the ink as an air bubble could not be completely prevented from flowing into the nozzle. As a result, the ink jet device was disassembled, and then, the inside of the nozzle of the nozzle plate was cleaned to wash out the air bubble. Therefore, problems arose as to complicated work processing and degradation of continuous operation of the device.
Hence, a method for removing an air bubble from inside the ink jet nozzle has been demanded.
A first aspect of the present invention relates to an ink jet system having : an air bubble removing unit including: an ink jet body having a plurality of ink supply path; a nozzle plate connected to an end of the ink jet body and having a plurality of spaced nozzle holes therein; and a cap configured to cover the nozzle holes formed in the nozzle plate wherein a first ink channel space is formed continuous to the nozzle holes and the plurality of ink supply path, and a second ink channel space is formed between a recess of the cap and a surface of the nozzle plate, so that the second ink channel space and the first ink channel space are continuous through the nozzle holes.
A second aspect of the present invention relates to a method for removing air bubbles in an ink jet comprising an ink jet body having a plurality of ink supply path and a nozzle plate connected to an end of the ink jet body and having a plurality of spaced nozzle holes therein, a first ink channel space is formed continuous to the nozzle holes and a second ink channel space is formed between a recess of a cap covering the nozzle plate and a surface of the nozzle plate, the second ink channel space and the first ink channel space are continuous through the nozzle holes; the method comprising: filling ink into the first ink channel space and the second ink channel space; and applying a pressure to the ink, so as to dissolve air bubbles in the ink in accordance with Henry's law.
A description will be given below by way of embodiments according to the present invention, which is not limited thereto. Here, constituent components having the same or similar functions are designated by the same or similar reference numerals, and therefore, their explanation will be omitted below.
An object of the present invention is to increase the solubility of an air bubble dispersed in ink, so as to remove the air bubble from inside of an ink jet nozzle. According to the present invention, the air bubble inside of the ink jet nozzle can be removed by increasing the solubility of the air bubble dispersed in the ink.
An ink jet system 1 for use in a first embodiment shown in
The bubble removing unit 30 shown in
When the nozzle plate 82 is attached to the ink jet body 81, a first ink channel space 85 is formed continuous to the plurality of nozzle holes 82a to 82f and the plurality of ink supply path 86a and 86b, and a second ink channel space 95 is formed between a recess of the cap 9 and the surface of the nozzle plate 82, so that the second ink channel space 95 and the first ink channel space 85 are continuous through the nozzle holes 82a to 82f. The cap 9 is attached to the surface of the nozzle plate 82 via packings 12a and 12b so as to cover the nozzle holes 82a to 82f of the nozzle plate 82.
The plunger pump 20 includes a suction tank 3, a vertically movable piston 31, valves 5a and 5b, and the inert gas unit 6. After the valve Sa is opened, the piston 31 is moved toward a bottom dead center shown in
Although
(a) The ink jet system 1 shown in
(b) The first ink channel space 85 and the second ink channel space 95, which are connected to each other via the nozzle holes 82a to 82f, are closed. Specifically, the valve 5c shown in
(c) The first ink channel space 85 and the second ink channel space 95 are filled with ink. Specifically, the plunger pump 20 is actuated, as shown in
(d) A pressure is applied to the ink 4, and air bubbles are dissolved in the ink 4 in accordance with Henry's law. Specifically, a pressure is applied to the ink 4 flowing in either one of the first ink channel space 85 and the second ink channel space 95. Here, the piston 31 in the plunger pump 20 is moved, as shown in
(e) The pressure applied to the ink is moderately decreased at about 1 KPa/min. to about 100 KPa/min. If the pressure is rapidly decreased, the pressure will lose uniformity. Here, the pressure is applied to the ink 4 flowing in the first ink channel space 85, so that the pressure of the ink 4 is uniform everywhere inside the closed space.
(f) When the pressure applied to the ink reaches about 98 KPa or less, the cap 9 is detached. In the above-described procedures, the air bubbles inside the ink jet 8 can be removed.
In accordance with “Henry's law”, in the case of gas having low solubility and does not react with a solvent, the mass of the gas to be dissolved in a defined amount of solvent at a given temperature is proportional to a pressure of the gas in contact with the solvent. Air bubbles contained in the ink 4 have a low solubility with respect to the ink 4. Therefore, the air bubbles do not react with the ink 4. Therefore, the air bubbles are dissolved in proportion to the pressure applied to the ink 4 in accordance with Henry's law. As a consequence, the air bubbles in the ink 4 are dissolved and removed from the ink 4, adhered to the nozzle side surface 82anw of a nozzle 82an shown in an enlargement view of the nozzle hole 82a inside of the ink jet 8 in
An ink was prepared so as to have air bubbles therein. The air bubble removing method in the first embodiment was implemented with respect to 60 ink jets for 60 seconds. As a result, the air bubbles inside the nozzle could be removed in all of the ink jets. In contrast, air bubbles inside the nozzle could be removed in only 3 out of all of the 60 ink jets in the case where the ink is only degassed.
Explanation will be made on mainly a difference between a second embodiment and the first embodiment. An ink jet system 51 for use in the second embodiment illustrated in
With the method for removing air bubbles from inside an ink jet nozzle in the second embodiment using the ink jet system 51 configured inside the ink jet nozzle, a pressure is applied to the ink 4 of the second ink channel space 95 and a first ink channel space 85 from a surface side of a nozzle plate 82. The pressure applying method is identical to that of the method for removing the air bubbles inside the ink jet nozzle of the first embodiment. In the second embodiment, the air bubbles inside of the ink jet nozzle can be removed in the same manner as in the first embodiment. The first embodiment and the second embodiment may be used in combination.
As described above, although the present invention has been described by way of the embodiments, it is to be understood that the description and the drawings composing a part of the disclosure should not limit the present invention. From this disclosure, various alternative modes, examples, and operational techniques are obvious for one skilled in the art. For example, although the ink 4 is supplied to the first ink channel space 85 and the second ink channel space 95 to increase the pressure in the embodiments, an inert gas may be fed into the first ink channel space 85 and the second ink channel space 95, to thus apply a pressure to the ink 4.
In this manner, it is, of course, to be understood that the present invention should include various embodiments, although they are not described herein. As a consequence, a technical range according to the present invention shall be determined only by an invention specifying matter encompassed within a scope of claims which seems proper from the above description.
| Number | Date | Country | Kind |
|---|---|---|---|
| P2008-027526 | Feb 2008 | JP | national |
