JP5283874B2 - Discharge preparation method for ink jet coating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge preparation method for an inkjet type application apparatus which is prevented from wasting ink and has excellent workability in the discharge preparation of ink from each coating head at a waiting position. <P>SOLUTION: A cap 8 is fitted to a nozzle 32 end of the coating head 3, the pressure in an ink housing part 5 housing the ink used for application is opened to the atmosphere from a negative pressure state when the ink housing part 5 is positioned above each coating head, a space is provided between the tip part of each coating head and the cap to exude the ink from the space C. After the cap is removed, the ink housing part is evacuated again. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an ejection preparation method for an ink jet coating apparatus for forming a meniscus that can eject ink from a coating head.

  In order to directly form a fine conductive pattern or the like on the surface of a substrate without going through a photolithography process, it is known to use an in-jet coating apparatus. In recent years, in a thin film transistor substrate manufacturing process, a high definition of several μm is used. It is also used to form source / drain electrode patterns, or to form color filters and alignment films for flat panel displays.

  As an ink jet type coating device used for the above-mentioned application, since it is easy to adjust the amount of ink discharged from the coating head, it communicates with an ink tank (ink storage unit) serving as an ink supply source via an ink passage. It is known to use a drop-on-demand type apparatus in which a plurality of coating heads each including an ink chamber and a piezoelectric element (piezo element) provided in the ink chamber are arranged (for example, Patent Document 1).

  In this case, when the inside of the ink tank is held at a negative pressure and the ink is drawn into the ink tank side and then deformed by applying a predetermined driving pulse voltage to the piezoelectric element, for example, the volume in the ink chamber is increased. It increases and the pressure inside it decreases. At this time, ink is drawn into the ink chamber from the ink passage. When the voltage application is stopped, the piezoelectric element returns to the original state, the volume in the ink chamber is reduced and the pressure is increased, and the ink is pushed out from the nozzle end of the coating head and ejected.

  In such an ink jet coating apparatus, for example, after maintenance is performed, preparation for discharging ink is usually performed at a standby position apart from the substrate to be coated, prior to ink coating on the substrate. Here, when the ink is not applied to the substrate (when the application head is in the standby position), a cap is attached to the nozzle end of the application head for the purpose of preventing drying.

In the conventional ink discharge preparation, after removing the caps attached to the nozzle ends of the respective coating heads, the ink is forcibly pushed out from all the coating heads by pressurizing the ink tank. . Then, after the pressurization is stopped, the ink pool remaining at the nozzle end of the coating head is wiped with a wiper blade or the like, and the inside of the ink tank is again decompressed to regenerate a meniscus that can eject ink from the coating head.
JP 2002-207112 A

  However, when the inside of the ink tank is pressurized and the ink is forcibly pushed out from all the coating heads as in the above-described ejection preparation, a large amount of ink is ejected from each coating head, and the ink is wasted. There is a problem and a large amount of ink is wasted when the number of application heads is large. In addition, when the pressurization is stopped, a large amount of ink pool may remain around the nozzle end of the coating head. In this case, the ink cannot be wiped off efficiently by a wiper blade or the like, and it takes time to prepare for ink ejection.

  Therefore, in view of the above points, an object of the present invention is to discharge an inkjet coating apparatus with good workability so that ink is not consumed wastefully when preparing to discharge ink from each coating head at a standby position. It is to provide a preparation method.

In order to solve the above-described problem, the ink jet coating apparatus discharge preparation method of the present invention is configured such that a cap is attached to the nozzle end of the coating head, and an ink storage unit storing ink used for coating is positioned above the coating head. In this state, the inside of the ink storage unit is released from the negative pressure to the atmosphere, and by lowering the cap, a gap is provided between the tip of the coating head and the cap so that the ink oozes out and the cap is removed. Then, the ink container is decompressed.

According to the present invention, when the ink storage portion is released from the negative pressure state to the atmosphere, the ink is pushed out by its own weight toward the coating head positioned below the ink storage portion. When forming a gap between the coating fabric head and the cap, the ink from the nozzle end of the applicator head is spread exudes slowly. Next, when the cap is removed, a small amount of ink pool is formed at the nozzle end of the coating head, and then the ink storage portion is decompressed again. At this time, the ink in the coating head is drawn again in the direction of the ink storage portion, and a meniscus is formed (regenerated).

As described above, in the present invention, the ink is not forcedly pushed out from the coating head by pressurizing the inside of the ink tank, but the ink is gently pushed out by its own weight so that the ink is oozed out into the gap. Is prevented from being wasted. At that time, air bubbles and foreign matter generated or mixed in the ink passage leading to the coating head also its weight is easily discharged from the nozzle end by the ink acting, can prevent the coating fabric head becomes defective discharge state.

In the case where is detached the previous Kiki cap preferably further comprises the step of wiping the ink reservoirs are formed in the nozzle end of the coating head. In this case, since a small amount of ink remains at the nozzle end of the coating head after the cap is removed, the workability of wiping off ink around the nozzle is good.

  Further, in the case where a plurality of the coating heads are arranged in a row so that the nozzle ends thereof are positioned on the same plane, the nozzles of the coating heads are used in order to facilitate control of the ejection preparation. What is necessary is just to employ | adopt the structure using one cap which seals an end simultaneously.

  If it demonstrates with reference to FIG.1 and FIG.2, 1 is the inkjet type coating device of this Embodiment. The ink jet coating apparatus 1 is placed on a substrate stage 2 on which a substrate (object) S to be processed such as a glass substrate or a silicon wafer is positioned and placed, and on the substrate stage 2 above the substrate stage 2. A plurality of coating heads 3 for discharging and coating ink on the substrate S are provided.

  The coating heads 3 are arranged at equal intervals so that nozzle ends, which will be described later, are positioned on the same plane, and are held by holders 4 connected to driving means (not shown). Then, under the control of a control means (not shown), each coating head 3 moves integrally on the substrate S in the XY direction and applies ink in a predetermined pattern.

  As shown in FIG. 3, each coating head 3 having the same structure has a head body 31, and a nozzle 32 is formed at the lower end of the head body 31 so as to face the substrate S. The nozzle 32 communicates with an ink chamber 34 having a predetermined volume via an ink passage 33. The ink chamber 34 is provided with a piezoelectric element (piezo element) 35 having a known structure in order to change the volume in the ink chamber 34, and the upstream side of the ink chamber 34 (upper side in FIG. 3) The ink passage 36 is in communication. An ink supply pipe 37 is connected to the end portion of the ink passage 36 that communicates with the upper surface of the nozzle body 31, and the other end of the ink supply pipe 37 is positioned above the coating head 3 to store predetermined ink. Connected to the ink tank 5 (ink storage portion).

  Here, the ink stored in the ink tank 5 is appropriately selected according to what is to be formed on the surface of the substrate S. For example, if it is for an alignment film, an ink made of polyamic acid is used. . In the ink jet coating apparatus for this application, one to three coating heads 3 are used. The capacity of the ink tank 5 in this case is 20 ml, and the ink application to the substrate S is started. The ink is stored in the ink tank 5 in the same amount, and at this time, the discharge amount from the coating head 3 is about 45 pl.

  The ink tank 5 is provided with suction means such as a vacuum pump (not shown). By operating the suction means to make the ink tank 5 have a pressure (negative pressure) lower than atmospheric pressure, the ink in the coating head 3 is removed. Is drawn toward the ink tank 5 so that ink is not ejected from the nozzles 32. When a predetermined pulse voltage is applied to the piezoelectric element 35 and deformed, for example, the volume in the ink chamber 34 increases and the pressure in the ink chamber 34 decreases, so that the ink is supplied from the ink supply pipe 37 through the ink passage 36. Is drawn into the ink chamber 34. Next, when the voltage application is stopped, the piezoelectric element 35 returns to the original state, the volume in the ink chamber 34 decreases, the pressure increases, and the ink is pushed out from the nozzle 32 and ejected.

  In addition, a substantially box-shaped ink receiving portion 6 having an upper surface opened is provided on one side of the substrate stage 2, and the space above the ink receiving portion 6 allows each coating head 3 from the substrate stage 2 and eventually the substrate S. Separated standby positions are formed (see FIGS. 1 and 2). A nut member 71 is provided on the outer wall of the ink receiving portion 6, and a feed screw 72 having a driving means such as a motor is screwed into the nut member 71, whereby the ink receiving portion 6 is attached to the coating head 3. It can move up and down.

  An integrated cap 8 is provided on the bottom surface of the ink receiving portion 6 to seal the ends of the nozzles 32 of the coating heads 3 arranged in a row. Then, after moving each coating head 3 to the standby position, when the ink receiving portion 6 is raised, the cap 8 is attached to the end of the nozzle 32 of each coating head 3.

  Further, a wiper blade 9 having a known structure is erected on one side in the longitudinal direction of the cap 8, and the ink receiving portion 6 is lowered to a position where the tip of the wiper blade 9 contacts the end of each nozzle 32. Thereafter, when each coating head 3 is moved in the X direction, the wiper blade 9 slides along the end of the nozzle 32 of each coating head 3, and ink droplets around the nozzle 3 can be wiped off. In the present embodiment, the ink receiving section 6 has a strobe light emitting device 61 having a known structure and the positions of ink droplets ejected from the nozzle 32 end of each coating head 3 by each strobe light emission of the strobe light emitting device 61. An observation device 62 such as a CCD camera for detection is provided. A control means (not shown) can detect the ink droplet ejection speed and the ink flying angle with respect to the extended line from the nozzle 32 from the ink droplet moving distance within the strobe emission interval.

  Next, for example, a method for preparing for discharge in the ink jet coating apparatus of the present invention, which is performed at the standby position prior to the application of ink to the substrate S after performing maintenance, will be described. At the standby position of each coating head 3, the cap 8 is attached to the end of the nozzle 32 of each coating head 3 by moving the ink receiving portion 6 to the raised position (see FIG. 4A). In this state, the ink tank 5 has a negative pressure.

  Next, the inside of the ink tank 5 located above each coating head 3 is released to the atmosphere. When the ink tank 5 is released to the atmosphere, the ink in the ink tank 5 is pushed out toward the nozzle 32 through the ink supply pipe 37 and the ink chamber 34 and the ink passages 33 and 36 in the head body 31 by its own weight. Ink is supplied to the end of the nozzle 3. Then, the ink receiving portion 6 is slightly lowered to form a predetermined gap C between the nozzle 32 end of each coating head and the cap 8. At this time, ink gradually oozes from the end of the nozzle 32 and spreads into the gap C (see FIG. 4B).

  Next, when the cap 8 is further lowered to form a predetermined space (detachment of the cap 8), a small amount of ink reservoir I is formed at the end of the nozzle 32 of the coating head 3 (FIG. 4 (FIG. 4). c)). Then, in a state where the ink receiving portion 6 is lowered to a position where the tip of the wiper blade 9 comes into contact with the end of each nozzle 32, each coating head 3 is moved integrally in the X direction. Thereby, the ink reservoir I around the nozzle 32 of each coating head 3 is wiped off (see FIG. 4D).

  Finally, when the pressure of the ink tank 5 is reduced again, the ink in the head main body 31 is drawn again toward the ink tank 5 and the meniscus is regenerated (see FIG. 4E). As described above, in the ejection preparation method of the present embodiment, the ink is not forcedly pushed out from the coating head 3 by pressurizing the inside of the ink tank 5, but the ink is pushed out by its own weight, and the ink is gently put into the gap. Since the ink is oozed out, ink is prevented from being wasted. At that time, bubbles and foreign matters generated or mixed in the ink passages 33 and 36 leading to the application head 3 are easily discharged from the end of the nozzle 32 by the ink acting on the self-weight, and each application head 3 is in a defective discharge state. Can be suppressed. Furthermore, since a small amount of ink remains at the nozzle end of the coating head 3 after the cap 8 is detached, workability for wiping off ink around the nozzle is good.

  In the present embodiment, the application nozzle using a piezoelectric element is used to supply ink from the ink tank to each application head. However, the form of the application head and the ink to the application head are described. For example, the present invention can be applied to a thermal-type coating head.

The typical principal part enlarged plan view of the inkjet type coating device which can implement the discharge preparation method of this invention. The typical front view of the coating device shown in FIG. Sectional drawing explaining an application | coating head. (A) thru | or (d) is a figure explaining the coating head explaining the discharge preparation of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet type coating apparatus 2 Substrate stage 3 Coating head 32 Nozzle 33, 36 Ink passage 34 Ink chamber 35 Piezoelectric element 5 Ink tank (ink storage section)
6 Ink receiving part 8 Cap 9 Wiper blade

Claims (3)

A cap is attached to the nozzle end of the application head, and the ink storage part containing ink used for application is located above the application head, the inside of the ink storage part is released from the negative pressure state to the atmosphere, and the cap is lowered. ink is ooze into the gap by providing a gap between the tip and the cap of the coating head by, after detaching the cap, ink-jet, characterized in that for reducing the pressure of the ink containing portion Dispensing preparation method for coating apparatus.   2. The method of preparing for ejection of an ink jet coating apparatus according to claim 1, further comprising a step of wiping off an ink reservoir formed at a nozzle end of the coating head when the cap is detached.   When a plurality of the coating heads are arranged in a row so that the nozzle ends thereof are positioned on the same plane, one cap is used to seal the nozzle ends of the coating heads at the same time. The discharge preparation method of the ink jet type coating apparatus according to claim 1 or 2.

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