KR20090098688A - Coating machine and its ink filling method - Google Patents

Abstract

A coating machine and an ink filling method are provided to eject bubble staying at the place where the ink is jammed. A sub tank(6) fills the main tank(4) with ink. The ink of the main tank is charged to the whole fluid connection to the nozzle of the inkjet head(1) from the feeding line(3). The high pressure about 80-150KPa is assigned to the main tank by the manipulation of 3 way valve. A supply electronic valve(10) is closed and the main tank is opened by the manipulation of 3 way valve(7B). The high pressure about 80-150KPa is assigned to the main tank for several minutes by the manipulation of 3 way valve. The low pressure about 15-30KPa is given by the manipulation of 3 way valve. The standby state capable of the discharging of the ink is made and the action for the preparation of the printing is completed.

Description

Coating device and ink filling method {COATING MACHINE AND ITS INK FILLING METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a coating apparatus and an ink filling method by an inkjet system which are essential for improving the operation rate of the apparatus in a large coating apparatus employing an ink-jet system.

The printing or coating apparatus employing the inkjet method has been developed as a compact printing apparatus for business or consumer use, and can be used as a printing apparatus for home or business, as well as for applications in industrial printing processes or large outdoor areas. It is widely applied as a large-format printing apparatus in advertising media. Among these, in recent years, the apparatus which employ | adopted the inkjet system for the manufacture of the color filter as a key device of display apparatuses, such as a liquid crystal television, is introduced.

Application of the coating device in the production of color filters is based on a color filter substrate having a fine lattice-shaped light shielding portion called a "black matrix" on a surface of thin glass. (Iii), it is used as an apparatus for discharging ink to the fine section (pixel) formed by the lattice of a light shielding part.

As the size of the color filter increases in size, the effective area of the color filter is increasing in response to the increase in size of the video device, which is a factor in the price increase of the color filter as a member. Increasing demand has led to a reduction in manufacturing costs. As a result, the demand for the coating device is increasing not only at the price of the device but also at high speed, stability, and reliability, which can contribute to manufacturing cost, such as the production of a high-speed color filter and the improvement of the machine operation rate as much as possible.

As a coating apparatus capable of meeting such a demand, a large coating apparatus capable of applying a large coating area at one time is naturally required from the above market demand as a use for manufacturing a large color filter.

On the other hand, in order to improve the productivity of the member produced by application | coating of ink, such as a color filter, it is necessary to ensure the operation continuity of the ink discharge of an application apparatus. As a method of realizing such continuous operation of the coating device, conventionally, a simple method is to clean the tip of the nozzle by wiping the tip of the nozzle directly with an absorbent material to wipe off excess ink. You can repeat this at an appropriate frequency.

In the conventional simple cleaning method of the nozzle, it is not a big problem in the application device having a low frequency of use because it is a small size for home use, but the frequency of use is high in a large apparatus used for industrial purposes, and the cleaning of the tip of the nozzle has a high frequency accordingly. In addition, since the total number of nozzles becomes enormous, the amount of ink to be wiped out also becomes a considerable amount, requiring a large amount of the absorbent to absorb this, and the space occupied by the installation becomes large. In the coating device of the present invention, there is a problem in practicality, and it is not suitable as a method corresponding to the problem of poor discharge of ink due to bubbles inside the nozzle.

As a method for improving the discharge failure of ink from a nozzle due to bubbles or the like remaining inside the nozzle, in a conventional coating apparatus, a filter is provided in a flow path to a nozzle for discharging ink. It is provided by the method (patent document 1) which carries out the 1st charge process of ink below the pressure which ink passes through a filter, and performs a 2nd charge process above the pressure which passes through a filter (patent document 1).

According to the method of Patent Literature 1, due to poor printing, that is, poor filling of ink, air remains in a place close to an orifice of the ink ejection portion, resulting in poor sealing, and air flows into the ink, thereby inhibiting the flow of ink. It is disclosed that printing defects that occur intermittently due to the ejection of the ink do not occur.

In addition, a recovery system of an inkjet recording apparatus is a generic term for a secondary mechanism that eliminates clogging caused by adhesion of ink to a nozzle or an ink passage. In the cited example, a suction pump, a cap, and the like are used. A cleaning method comprising: a first printing operation involving at least a first preliminary ejection operation of a predetermined amount before printing start or after printing is finished, and at least more than the predetermined amount before printing start or after printing is finished; And a second printing operation involving a second preliminary ejection operation of a second predetermined amount by a method of switching and executing the second printing operation based on the determination criteria (Patent Document 2).

By the method of this Patent Document 2, it is possible to prevent the ink from adhering to the ink flow path, and to maintain a state in which normal normal discharge is possible, for example, "suction" and "preliminary discharge". It is disclosed that an operation such as this is performed properly, so that a long time operation and good printing are maintained.

Patent Document 1: Japanese Unexamined Patent Publication No. 2004-114658

Patent Document 2: Japanese Unexamined Patent Publication No. 2002-52740

In the method of avoiding mixing of air and the like into the ink flow path of the ink entering the nozzle according to Patent Document 1, a stable operation can be expected so that there is no problem in practical use in a relatively small coating apparatus, and in the method of Patent Document 2, the ink is fixed The effect as a countermeasure which pays attention to a problem, such as a congestion or almost sticking and the flow around a nozzle discharge port, is stagnant can be expected.

However, in the method of Patent Literature 1 or Patent Literature 2, the ink in the vicinity of the nozzle is stagnant in all of the heads in the coating apparatus having a large number of heads that discharge ink, such as a commercial coating apparatus. It is not enough to remove air bubbles attached to the wall of the place.

For this reason, by compressing a bubble in which an impact (rapid pressure rise) for ejecting ink from the nozzles is compressed, considerable energy is absorbed and ink is not ejected properly. There was a problem that adjustment and the like were necessary and the coating device could not be used immediately.

The inventors have once again considered a method of filling ink that enables proper ink ejection from all nozzles from the start of production in a coating apparatus having a plurality of nozzles for industrial use, and the like. Filling by application of a single pressure to the ink supply pipe, for example, ink applied to the ink supply passage, 1) filling ink at a pressure as low as 15-30 KPa (hereinafter referred to as low pressure) or 2 1) filling at a medium pressure of 30 to 80 kPa (hereinafter referred to as medium pressure) or 3) filling at a high pressure of 80 to 150 kPa (hereinafter referred to as high pressure). Supply operation in a coating apparatus requiring a very large number of nozzles, such as industrial ink jets, In the process, it was confirmed that it is not feasible to sufficiently remove the bubbles remaining in the place where the ink is stagnated just before the nozzle.

An object of the present invention is to provide an ink filling method and a device for reliably discharging bubbles remaining in a place where ink is stagnated just before a nozzle in such an ink supply path.

The present invention is a coating apparatus devised in view of the above problems and a filling method of the ink, the coating apparatus having an ink-jet head, a negative pressure applying means for applying a negative pressure, low pressure A low pressure applying means for applying a high pressure, a high pressure applying means for applying a high pressure and a control means, and a plurality of on / off valves and a switching valve controlled by the control means for an ink tank. And a low pressure applied to the tank to fill the ink from the tank to the nozzle discharging tip through the pipe passage as a filling step of the ink, and at least one of the tank is provided in the pipeline. Applying high pressure at a time and continuing, printing the pressure to the tank at least once from high pressure to low pressure as a process immediately before printing Each process is controlled and executed by a control means before printing.

Moreover, the pressure difference between high pressure application and low pressure application in the process immediately before printing is made 50 KPa or more. In addition, the upper limit of the low pressure application immediately before printing is set to 30 KPa.

According to the ink filling method of the inkjet coating apparatus of the present invention, as an ink filling step, a low pressure is applied to the tank to fill ink from the tank to a nozzle discharge tip portion through a pipe line, and then at least one high pressure is applied to the tank. When applied, it is possible to reliably remove the microbubbles present in the pipe wall and the connection portion of the piping system, and then, as a step immediately before printing, by switching the pressure applied to the tank one or more times from high pressure to low pressure. By applying the first high pressure, the micro bubbles adhering to the inside of the head nozzle and the nozzle inner wall are compressed, and the contact area with the nozzle inner wall is reduced due to the volume shrinkage of the bubbles, and the shape of the bubbles is closer to the spherical shape. It becomes the state that it is easy to flow, and from high pressure to low pressure The microbubbles in the nozzle were reliably discharged from the nozzle due to the sudden fluctuations in the pressure of the pressure (pressure swing).

As a result, the ink filling from the ink tank to the pipe or the discharge operation of bubbles in the nozzles of the entirety of the nozzles or the entire nozzles can be reliably performed in a short time as preparation for the start of printing of the inkjet coating device. It is possible to shorten the start-up of the apparatus or to reduce unnecessary waste of unnecessary ink in filling the ink, thereby making the most of the advantages of the inkjet coating technique, thereby greatly contributing to the improvement of productivity.

EMBODIMENT OF THE INVENTION Hereinafter, the best form for implementation of this invention is demonstrated using drawing.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a system configuration diagram showing the concept of a system that enables ink filling to an ink-jet head in an ink-jet coating apparatus according to the present invention. 2 is a block diagram of a system main part of a pressure air source for applying pressure to a main tank 4, and FIG. 3 is a process flowchart of the system. In the inkjet head 1 in which the nozzle (not shown) is formed, the ejection operation and the stop of the ink from the nozzle of the inkjet head 1 are controlled by a command from the head control board 2. do. The inkjet head 1 is connected to a main tank 4 through an ink supply pipe 3 to supply ink. As the main tank 4, the ink is replenished by being directly connected to the sub tank 6 through the ink replenishment pipe 5.

The main tank 4 is connected with a vacuum pump 8 and a pressure air source 9 which are "negative pressure application means for applying a minus pressure" through a plurality of three-way selector valves 7A and 7B. . The ink supply pipe (3) and the ink refill pipe (5) are provided with a supply solenoid valve (10) and a supplementary solenoid valve (11), and the valves are supplied by a command from the system control means (not shown) of the entire apparatus. Opening and closing operation is made. Fig. 2 is a block diagram showing the inside of the pressure air source 9 for applying the pressure to the main tank 4, and shows "low pressure applying means for applying low pressure" for generating a low pressure of about 15 to 30 KPa. Two pressure sources: 9L phosphorus low pressure source (9L) and high pressure source (9H) which is a "high pressure application means for applying high pressure" that generates a high pressure of about 80 to 150 KPa. The low pressure and the high pressure in the source are appropriately applied to the main tank 4 by the three-way selector valve 7C through the pressure regulator.

EMBODIMENT OF THE INVENTION Below, the ink filling method of this invention is demonstrated in detail, referring drawings of the process flow of FIG. In the first step, first, as a refilling step of ink from the sub tank 6 to the main tank 4, the supply solenoid valve 10 is closed and the replenishing solenoid valve 11 is opened in a vacuum state. The pump 8 is started to operate the three-way selector valve 7A to bring the main tank to negative pressure. Ink is replenished from the sub tank 6 to the main tank 4 by keeping the main tank 4 at a negative pressure. After this inflow amount reaches the appropriate amount, the 1st process is complete | finished with the supplemental solenoid valve 11 being "closed."

In the second process, the supply solenoid valve 10 is set to "open" and 15-30 KPa through the pressure regulator from the low pressure source 9L of the pressure air source 9 by operation of the 3-way selector valve 7C. The low pressure of the degree is applied to the main tank 4, and the ink of the main tank 4 is filled in the whole piping part from the supply piping 3 to the nozzle of the inkjet head 1. FIG.

In the third process, immediately after the completion of the second process, by operation of the three-way selector valves 7A, 7B, and 7C, about 80 to 150 KPa from the high pressure source 9H of the pressure air source 9 through the pressure regulator. After the high pressure was applied to the main tank 4 to confirm the ejection of the ink from all the nozzles, the supply solenoid valve 10 was "closed" and the main tank was awaited by operation of the three-way selector valve 7B. Open with). As a result, minute "bubbles" remaining in the ink supply pipe, such as the pipe bent portion or the pipe connection portion from the main tank 4 to the nozzle of the ink jet head 1 or scattered in the ink, are discharged from the nozzle of the ink jet head 1. . The third step may be repeated.

However, in the filling method up to this stage, in the coating apparatus having a large number of industrial nozzles, it is not sufficient to remove the bubbles remaining immediately before the whole nozzles, especially where the ink inside the head is stagnant. Therefore, even if it moves to a printing operation by giving a predetermined negative pressure from this state, the nozzle which does not discharge ink will generate | occur | produce.

Effective use of the device for a limited time (ie, improvement of operation rate) is a proposition above ground for both the enterprise and the device developer, where the ink just before the nozzle in the ink supply path is stagnated. In order to reliably remove the bubbles adhering to and staying on the wall surface of the supply path, the fourth to sixth steps are described below.

In the fourth step, the supply solenoid valve 10 is " opened " and stays in the ink supply pipe such as a pipe bent portion or a pipe connection portion from the main tank 4 to the nozzle of the inkjet head 1 or is scattered in the ink. In order to discharge a minute "bubble" from the nozzle of the inkjet head 1, 80 to 80 through the pressure regulator from the high pressure source 9H of the pressure air source 9 again by operation of the three-way selector valve 7B. A high pressure of about 150 KPa is applied to the main tank 4 for a few seconds and immediately moves to the fifth process.

At this time, in the ink supply path close to the nozzle, such as where the ink is stagnant, if there are bubbles adhering to the wall surface, the volume decreases in inverse proportion to the pressure increase due to the pressure increase, and the contact area with the wall surface in the supply path. Since this decreases, the shape of the bubbles also becomes closer to the spherical shape, and the flow becomes easy. Therefore, the pressure at this time is high, so that the volume change of the air bubbles staying in this way becomes large and the contact area with the wall surface is reduced, which is preferable because the fluidity of the bubbles becomes higher, but when the fluidity of the bubbles is too high and the time becomes too long, it flows out of the nozzle. The amount of ink to be increased is undesirable.

In the fifth step, after the ink is discharged by applying the high pressure in the fourth step, the low pressure source 9L of the pressure air source 9 is supplied to the main tank 4 by the operation of the three-way selector valve 7C. Apply a low pressure of 15 ~ 30KPa through the pressure regulator. As a result, through the fourth step, the fluidity is increased and bubbles adhered to the wall surface of the portion close to the nozzle, such as where the ink is stagnant, are discharged out of the nozzle together with the ink, thereby eliminating bubbles in the ink supply path near the nozzle. After the fourth step and the fifth step, the fourth step and the fifth step may be repeated as necessary.

In addition, the difference in pressure (differential pressure) between the fourth step and the fifth step is 50 KPa, and preferably, a pressure difference higher than that, thereby making it possible to more reliably remove the bubbles remaining on the wall surface.

In addition, if it is possible to simultaneously close all the nozzles in the sealed state in the fourth process, a pressure of about 80 to 150 KPa is applied to the main tank 4 from the high pressure source 9H of the pressure air source 9 through the pressure regulator. After applying for a few seconds, the membrane can similarly exhibit the abnormal state of the fifth process from the fourth process by opening the nozzle, so that it is expected to discharge the airborne bubbles, such as adhered to the wall, near the nozzle. have.

In the above-described second, third, fourth, and fifth steps, when the fourth and fifth steps are performed without the second and third steps, piping from the tank to the head is carried out. The air bubbles initially present in the part suddenly flow into the head and fill the place where the filter part or the ink inside the head is stagnant, thereby obstructing the flow of ink due to an air lock phenomenon or discharging air. Since the inflow of the ink cannot be made smoothly, and the inflow of the ink is difficult for a short time, the ink can be consumed more than necessary to replace the inflow of the ink, so that the efficient ink filling operation cannot be performed.

In the sixth step, the vacuum pump 8 is started and a predetermined negative pressure is applied to the main tank 4 by operating the three-way selector valve 7A (in this example, a variation of 0.5 KPa around -1 KPa). By providing the ink jet nozzles, all the ink jet nozzles of the ink jet head 1 form an appropriate meniscus (gas-liquid interface of the nozzle discharge port), and the ink jet head 1 becomes a standby state where ink can be discharged. The preparation for the operation before printing is completed.

From this state, by giving a control command (signal) to the head control board 2 from the system control means (not shown in the figure), the ink jet is continuously or discharged in accordance with the timing at which the ink droplets should be discharged in accordance with the control command. The normal coating (printing) operation of discharging ink from the nozzle of the head 1 can be performed.

Next, the method of confirming the quality of the ink filling method to the inkjet head 1 will be described in detail. This time, it confirmed with the coating apparatus which mounted the inkjet head in the following procedure.

First, the twelve inkjet heads each independently check the ejection operation of the ink, and confirm that the continuous ejection operation of the ink is performed without abnormality in the independent operation.

Next, in the coating apparatus equipped with these 12 inkjet heads (four colors of red, green, and blue, the total number of nozzles: 6144 holes), the coating apparatus is not filled with the fourth and fifth steps. (Hereinafter, referred to as a conventional method), that is, after the filling step of the ink which performs the sixth step after the first step to the third step, the normal coating operation was performed. As a result, although the single head had 12 heads in which the continuous discharge operation of the ink could be confirmed, the continuous discharge operation of the ink was simultaneously performed in the coating apparatus equipped with 12, so that the droplets from some nozzles could be removed from the beginning. It was confirmed that there was a lack of impact. This means that there are a considerable number of nozzles in which bubbles remain in the supply path close to the nozzle.

In the inkjet head coating apparatus of the inkjet head of 12 heads (four colors of red, green, and blue, and 4,144 nozzles each), which have confirmed the continuous ejection operation without any abnormality, the inkjet according to the present invention is provided. The ink filling method to the head, that is, the ink filling method from the first step to the sixth step, was carried out, and normal application | coating operation | movement was performed and the state of the ink continuous discharge operation | movement from all the nozzles was confirmed. As a result, in the method of this invention, the impact of the droplet of all the nozzles of 12 inkjet heads was confirmed from the beginning.

In addition, in order to confirm that such an ink filling method is effective even when the number increases, the ink filling method is applied to 72 inkjet heads (24 colors of red, green, and blue, and total number of nozzles: 36864 holes). It confirmed by the coating apparatus mounted. As a result, even when the number of nozzles was increased by 6 times, it was confirmed that continuous ejection operation was possible from the beginning, so that no ink deficiency occurred at all.

Experimental Example

As a specific example, the comparative experiment regarding the determination of the quantity of ink ejection when the device is started by filling the inkjet head by the ink filling method according to the conventional method and the present invention will be described in detail.

For the comparative experiments, the process immediately before the confirmation of the ink ejection / absence as a condition before the test was commonized as follows to obtain objectivity of the results as follows.

1) The cleaning liquid (organic solvent such as PMA) in the head is discharged.

2) Ink is filled into the inkjet head by the respective methods of comparison.

3) Cleaning: Wiping around the nozzle with nonwoven fabric.

4) flushing: ejecting ink from the entire nozzle.

5) Test print (Check for lack of ink)

In addition, the process after the test,

1) Forced discharge of all ink from the main tank to the nozzle

2) It was common to fill the cleaning liquid (filling from the main tank to the nozzle).

(Experimental result of the conventional method)

The ink ejection results from the nozzles after the ink filling by the conventional method will be described below. As a first step, the supply solenoid valve and the supplementary solenoid valve 11 are "closed" together, the vacuum pump 8 is started, and the negative pressure is applied to the main tank 4 by operating the three-way selector valve 7A. The first step of supplying an appropriate amount of ink from the subtank 6 to the main tank 4 by applying the supplementary solenoid valve 11 to "open", and closing the supplementary solenoid valve 11 "closed." It was made.

As a second process, a low pressure of 15 to 30 KPa is applied to the main tank 4 from the low pressure source 9L of the pressure air source 9 through the pressure regulator by the operation of the three-way selector valves 7A, 7B, and 7C. Then, the ink was filled in the nozzle of the inkjet head 1 from the main tank 4 through the ink supply pipe with the supply solenoid valve "open". As a result, air in the supply pipe is discharged, and ink is finally discharged from the nozzle.

Subsequently, as a third process, 140 KPa high pressure is applied to the main tank 4 from the high pressure source 9H of the pressure air source 9 through the pressure regulator by the operation of the three-way selector valve 7C. After confirming the ejection of the ink, the supply solenoid valve 10 is "closed" and the main tank is opened to the atmosphere by the operation of the three-way selector valve 7B. In this way, the ink was filled by discharging and removing the retained bubbles at the same time as the discharge of the ink. As a result, fine bubbles in the supply pipe not discharged at low pressure are discharged.

Thereafter, as the fourth step, the supply solenoid valve 10 is " opened ", the vacuum pump 8 is started, and a predetermined negative pressure is applied to the main tank 4 by the operation of the three-way selector valve 7A. (In this example, a fluctuation range of 0.5 KPa around-1 KPa), the sixth step was completed in which all the ink jet nozzles of the ink jet head 1 made an appropriate meniscus.

And it confirmed in the application | coating operation (test printing) which discharges ink from the inkjet nozzle of an application apparatus.

As a result of counting the number of ink droplets which landed on the glass substrate for color filters by this coating operation, as shown in Table 1, the number of nozzles (the number of nozzle defects) that could not confirm droplet landing was 20 to 20. 29 cases occurred.

Table 1

Red green blue Nozzle total number 12288 12288 12288 Nozzle Defects 20 22 29 Discharge rate (%) 99.84 99.82 99.76

(Experimental result of the method of the present invention)

The result by the ink filling method to the inkjet head 1 of this invention is demonstrated below.

As in the conventional method, as the first step, the supply solenoid valve and the supplementary solenoid valve 11 are "closed" together, the vacuum pump 8 is started, and the main tank 4 is operated by operating the three-way switching valve 7A. ), A negative pressure was applied, and ink was supplied from the sub tank 6 to the main tank 4 with the supplemental solenoid valve 11 "opened."

As a second process, a low pressure of 15 to 30 KPa is applied to the main tank 4 from the low pressure source 9L of the pressure air source 9 through the pressure regulator by the operation of the three-way selector valves 7A, 7B, and 7C. With the supply solenoid valve set to "open", ink was filled into the nozzle of the inkjet head 1 from the main tank 4 through the ink supply piping.

Subsequently, as a third process, 140 KPa high pressure is applied to the main tank 4 from the high pressure source 9H of the pressure air source 9 through the pressure regulator by the operation of the three-way selector valve 7C. After confirming the ejection of the ink, the supply solenoid valve 10 is "closed" and the main tank is opened to the atmosphere by the operation of the three-way selector valve 7B. As a result, the ink was discharged and the ink was filled by the discharge and removal of the retained bubbles.

Subsequently, as the fourth step, the supply solenoid valve 10 is " opened, " and again 140 KPa from the high pressure source 9H of the pressure air source 9 by the operation of the three-way selector valve 7B. A high pressure of was applied to the main tank 4 for several seconds.

Immediately thereafter, as a fifth process, a low pressure of 15 to 30 KPa is supplied to the main tank 4 for several seconds from the low pressure source 9L of the pressure air source 9 through the pressure regulator by operating the three-way selector valve 7C. Authorized.

Then, as in Comparative Example 1, as a sixth step, a predetermined negative pressure (from -1 KPa in this example-0.5 KPa) was applied from the vacuum pump 8 to the main tank 4 by operating the three-way selector valve 7A. Fluctuation range), and the sixth step of making the meniscus appropriate for all the ink jet nozzles of the ink jet head 1 was completed.

Thereafter, it confirmed in the application | coating operation (test printing) which discharges ink from the inkjet nozzle of an application apparatus. As a result, as shown in Table 2, the number of "nozzle defects" dropped to zero or one.

Table 2

Red green blue Nozzle total number 12288 12288 12288 Nozzle Defects 0 One 0 Discharge rate (%) 100 99.99 100

From the results of this comparative experiment, it was confirmed that in the conventional ink filling method, the removal of bubbles remaining in the ink supply paths for all the nozzles is not sufficient, and a great effect on the ink filling method of the present invention.

Regarding this difference, in the present invention, in the fourth step, by applying high pressure to the main tank 4 to reduce the volume of the bubble, the contact area with the wall surface is reduced, and the shape of the bubble is more concrete ( It is deformed close to a sphere so as to be easily moved. After that, by applying a low pressure to the main tank 4 at a low pressure in the fifth step without space therebetween, bubbles close to the spherical shape are easily increased in volume and moved more easily to the outside of the nozzle together with the surrounding ink. You can think of it as being exhausted.

As a result, reliable ink ejection operation can be continuously performed, and proper ejection of ink from all nozzles can be performed from the start of use of the coating apparatus, thereby making it possible to contribute to production activities in a short time.

As described above, according to the present invention, as an ink filling step, a low pressure is applied to the main tank, the ink is filled from the tank to the nozzle discharge tip via a pipe line, and then at least one high pressure is applied to the tank so that the pipe wall of the piping system is connected. The pressure supply source to switch the pressure applied to the tank one or more times from high pressure to low pressure immediately before printing after making a suitable meniscus on all the ink jet nozzles of the ink jet head 1 after removing the minute bubbles present in the connection portion And control of the opening and closing valves, etc., can significantly reduce the nozzle discharge and, as a result, an inkjet head having a plurality of nozzles, such as an industrial inkjet coating apparatus, can be applied without a nozzle defect number. Original features of inkjet coating Improving the quality of Lin coated products, it can contribute significantly to the cost of the product down.

INDUSTRIAL APPLICABILITY The present invention can be applied to a large apparatus such as a coating apparatus comprising a plurality of inkjet heads among coating apparatuses by an inkjet method.

1 is a system configuration diagram of an application apparatus.

2 is a block diagram of a low pressure and high pressure pressure source.

3 is a process flow diagram of the system of the applicator.

Explanation of symbols on the main parts of the drawings

1: inkjet head 2; Head control board

4 main tank 8 vacuum pump

9: pressure air source

Claims (6)

An applicator having an ink-jet head, comprising: a negative pressure applying means for applying a minus pressure, a low pressure applying means for applying a low pressure, and a high pressure for applying a high pressure A high pressure applying means and a control means, and a plurality of on / off valves and switching valves controlled by the control means in a conduit to an ink tank, In the ink filling step, a low pressure is applied to the tank to fill ink from the tank to the nozzle discharge tip through the pipe line, and then at least one high pressure is applied to the tank. , An ink filling method of an inkjet coating apparatus, comprising a step of switching the application of pressure to a tank from a high pressure application to a low pressure application one or more times immediately before printing. The method of claim 1, An ink filling method wherein a pressure difference between high pressure application and low pressure application in a step immediately before printing is 50 KPa or more. The method according to claim 1 or 2, An ink filling method, wherein the upper limit of low pressure application immediately before printing is 30 KPa. An applicator having an inkjet head, comprising: a negative pressure applying means for applying a negative pressure, a low pressure applying means for applying a low pressure, a high pressure applying means for applying a high pressure and a control means, and a pipe line of the ink tank to the control means. A plurality of on-off valves and switching valves controlled by An ink filling process controlled by the control means for applying low pressure to the tank to fill ink from the tank to the nozzle discharge tip portion through the pipe line, and then applying at least one high pressure to the tank; An inkjet coating device, characterized in that it comprises a process immediately before printing controlled by the control means for switching the application of pressure to the tank from the high pressure application to the low pressure application one or more times. The method of claim 4, wherein An inkjet coating apparatus, wherein a pressure difference between high pressure application and low pressure application in a step immediately before printing is 50 KPa or more. The method according to claim 4 or 5, An inkjet coating device characterized in that the upper limit of low pressure application immediately before printing is 30 KPa.

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