JP2007229608A - Liquid drop injection coating apparatus and liquid drop injection coating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent non-injection or injection failure of a liquid drop from a nozzle caused by bubbles existing in a liquid in a liquid drop injection coating head. <P>SOLUTION: The liquid drop injection coating apparatus 1 is provided with the liquid drop injection coating head 19 having a liquid chamber for storing the liquid and a plurality of nozzles communicated with the liquid chamber and a liquid drop injecting and caoting head 19 injecting the liquid drop from the nozzles, a temperature sensor for detecting a temperature of the liquid in the liquid drop injection coating head 19, a cooling unit 9 for cooling the liquid in the liquid drop injection coating head 19, and a movement means for moving the liquid drop injection coating head 19 to a cooling position by the cooling unit 9 based on the detection result of the temperature sensor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a droplet spray coating apparatus and a droplet spray coating method, and more particularly to a droplet spray coating apparatus for spraying droplets of ink or the like from a nozzle and a droplet spray coating method using the droplet spray coating apparatus. .

  As described in Patent Document 1 below, an inkjet recording apparatus is known as an example of a droplet spray coating apparatus that ejects droplets of ink or the like from a nozzle.

  Such an ink droplet spray coating apparatus has an ink spray coating head having a plurality of nozzles, an ink chamber communicated with these nozzles, and a piezoelectric element corresponding to each nozzle, and by driving the piezoelectric elements. Ink in the ink chamber is ejected from the nozzles as ink droplets.

  In some cases, air bubbles may be included in the ink in the ink chamber, and when these air bubbles enter the nozzle, non-ejection of ink droplets from the nozzle or poor ejection of ink droplets occurs. Specific examples of ink droplet ejection failure include variations in the ejection speed of ink droplets and a decrease in ink droplet landing accuracy.

Therefore, in the ink jet recording apparatus described in Patent Document 1, when a non-ejection or ejection failure of an ink droplet from a nozzle occurs, the nozzle portion is covered with a capping unit, and a negative pressure is applied to an area covered with the capping unit. The air bubbles that have entered the nozzle are sucked together with the ink to be removed.
JP 2001-18414 A

  However, the above-described inkjet recording apparatus does not consider the following points.

  Depending on the size of the bubble and the location where the bubble stays, the bubble that has entered the nozzle may not be removed even if a negative pressure is applied from the tip side of the nozzle.

  Moreover, even if the bubbles that have entered the nozzles can be removed by applying a negative pressure, the bubbles that adhere to the wall surface of the ink chamber cannot be removed. For this reason, even if the air bubbles in the nozzle can be removed, the air bubbles adhering to the wall surface of the ink liquid chamber enter the nozzle again, and ink droplets from the nozzles are not easily ejected and ejection defects are likely to occur again.

  Therefore, when bubbles are clogged in the nozzle, the bubbles are often not only present in the nozzle but also attached to the wall surface of the ink chamber. Therefore, in order to discharge the bubbles, the ink in the ink chamber is forced from the nozzle. In some cases, bubbles that are laminarly flowed out and flow out vigorously are discharged (also referred to as purge) together with the ink. However, bubbles that are large enough to clog the nozzles often adhere strongly to the wall surface of the ink chamber, and in order to discharge the bubbles, it is necessary to drain a large amount of ink, which is expensive. There is a problem that a large amount of ink is wasted.

  The present invention has been made to solve such problems, and its purpose is to prevent non-ejection and ejection failure of droplets from nozzles caused by bubbles present in the liquid in the droplet ejection application head. A droplet spray coating apparatus and a droplet spray coating method that can be prevented.

  A first feature according to an embodiment of the present invention is a droplet spray coating apparatus, which includes a liquid chamber that stores a liquid and a plurality of nozzles that communicate with the liquid chamber, and ejects droplets from the nozzle. Based on the detection result of the temperature sensor, the temperature sensor for detecting the temperature of the liquid in the droplet spray coating head, the cooling unit for cooling the liquid in the droplet spray coating head, and the temperature sensor. Moving means for moving the droplet spray coating head to a cooling position by the cooling unit.

  According to a second aspect of the present invention, in the droplet spray coating method, the step of detecting the temperature of the liquid in the droplet spray coating head, and the temperature of the liquid in the droplet spray coating head is A step of cooling the liquid when it is equal to or higher than a set value, and a step of discharging the cooled liquid from the nozzle of the droplet spraying application head.

  According to the present invention, it is possible to prevent non-ejection and ejection failure of droplets from a nozzle caused by bubbles present in the liquid in the droplet ejection coating head.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a droplet spray coating apparatus 1 according to an embodiment of the present invention includes a gantry 2, an ink coating box 3, and an ink supply box 4, and the ink coating box 3 and the ink supply box 4. Are fixed adjacent to each other on the gantry 2.

  Inside the ink application box 3, three inkjet head units 5, a substrate 6, a unit moving mechanism 7 that integrally moves the three inkjet head units 5 in the X-axis direction, and the substrate 6 in the X-axis direction and Y A substrate moving mechanism 8 that moves in the axial direction, a cooling unit 9, and three ink tanks 10 are housed.

  The unit moving mechanism 7 has a pair of support columns 11 erected on the upper surface of the gantry 2 and a guide plate 12 connected to the upper ends of the pair of support columns 11 and extending in the X-axis direction. A base plate 13 is attached to the guide plate 12 so as to be movable in the X-axis direction. The base plate 13 is provided so as to be movable along the X-axis direction by a feed mechanism (not shown) using a feed screw and a drive motor. An ink jet head unit 5 is attached to the guide plate 12.

  The substrate moving mechanism 8 includes a Y-axis direction guide plate 14, a Y-axis direction moving table 15, an X-axis direction moving table 16, and a substrate holding table 17.

  The Y-axis direction guide plate 14 is fixed to the upper surface of the gantry 2. A guide groove 14 a extending in the Y-axis direction is formed on the upper surface of the Y-axis direction guide plate 14.

  The Y-axis direction moving table 15 is disposed on the Y-axis direction moving plate 14, and a lower surface of the Y-axis direction moving table 15 is formed with a convex portion (not shown) that is movably engaged with the guide groove 14a. Yes. The Y-axis direction moving table 15 is provided so as to be movable in the Y-axis direction along the guide groove 14a by a feed mechanism (not shown) using a feed screw and a drive motor. A guide groove 15 a extending in the X-axis direction is formed on the upper surface of the Y-axis direction moving table 15.

  The X-axis direction moving table 16 is disposed on the Y-axis direction moving table 15, and a convex portion (not shown) that is movably engaged with the guide groove 15 a is formed on the lower surface of the X-axis direction moving table 16. ing. The X-axis direction moving table 16 is provided so as to be movable in the X-axis direction along the guide groove 15a by a feed mechanism (not shown) using a feed screw and a drive motor.

  The substrate holding table 17 is fixed to the upper surface of the X-axis direction moving table 16. The substrate 6 is placed on the upper surface of the substrate holding table 17. The substrate holding table 17 is provided with a substrate gripping mechanism 18 for gripping the placed substrate 6. As the substrate gripping mechanism 18, for example, a U-shaped sandwiching metal that sandwiches the four corners of the substrate 6 can be used. Instead of the substrate gripping mechanism 18, for example, a substrate suction mechanism that sucks the substrate 6 may be provided. As the substrate suction mechanism, for example, a rubber sucker or a suction pump can be used.

  The inkjet head unit 5 includes an ink droplet ejection coating head 19 that is a droplet ejection coating head, and a Z axis direction moving mechanism that moves the ink droplet ejection coating head 19 in a direction perpendicular to the upper surface of the substrate 6 (Z axis direction). 5a, a Y-axis direction moving mechanism 5b that moves the ink droplet ejection coating head 19 in the Y-axis direction, and a θ-direction rotation mechanism 5c that rotates the ink droplet ejection coating head 19 in the θ direction around the Z axis. Have. By these mechanisms 5a to 5c, the ink droplet ejection coating head 19 is movable in the Z-axis direction, the Y-axis direction, and the θ direction.

  As shown in FIG. 2, the ink droplet ejection coating head 19 includes a plurality of ink chambers 20 that are liquid chambers that store ink that is liquid supplied from the ink tank 10, and a part of the wall of each ink chamber 20. A diaphragm 21 to be formed, a plurality of piezoelectric elements 22 provided at positions in contact with the diaphragm 21 corresponding to the ink chambers 20, and a nozzle plate 23 that forms a part of the wall of each ink chamber 20. Yes. The nozzle plate 23 is formed with a plurality of nozzles 24 that communicate with the ink chambers 20. A temperature sensor 25 that detects the temperature of the ink in the ink droplet ejection coating head 19 is attached to the outer surface of the ink droplet ejection coating head 19. In the ink droplet ejection coating head 19, the piezoelectric element 22 is deformed in a contracting direction when a voltage is applied to the piezoelectric element 22, and this deformation causes the diaphragm 21 to bend in a direction of increasing the volume of the ink chamber 20, thereby increasing the volume. The amount of ink stored in the ink chamber 20 is increased. Subsequently, the piezoelectric element 22 that has shrunk is restored by cutting off the application of voltage, thereby restoring the volume of the ink chamber 20 and ejecting a portion of the ink in the ink chamber 20 as an ink droplet E from the nozzle 24. The ink droplet E ejected from the nozzle 24 is applied to a target position on the substrate 6. Each ink tank 10 contains inks of different colors (R (red), G (green), B (blue)), and three types of ink are supplied from the nozzles 24 of the ink droplet ejection application heads 19. Any one of the inks is ejected.

  The cooling unit 9 is disposed at a position on the extension line of the X axis that is the moving direction of the inkjet head unit 5 and away from the substrate holding table 17. Inside the cooling unit 9, a cooling mechanism using a Peltier element is housed. On the upper surface of the cooling unit 9, there are a cooling plate 26 that is cooled by a cooling mechanism, and an intermediate plate 27 that is provided on the upper surface of the cooling plate 26 and has a concave portion 27 a formed in the center.

  Inside the gantry 2, a control box 28 for controlling each part of the droplet spray coating apparatus 1 is provided. The control from the control box 28 causes the inkjet head unit 5 to move in the X-axis direction, the Y-axis direction moving table 15 to move in the Y-axis direction, and the X-axis direction moving table 16 to move in the X-axis direction. Further, by driving the Z-axis direction moving mechanism 5a, the Y-axis direction moving mechanism 5b, and the θ-direction rotating mechanism 5c, each ink droplet ejection coating head 19 moves in the Z-axis direction, the Y-axis direction, and the θ-direction. To do. Further, the ink jet head unit 5 is moved above the cooling unit 9 according to the detection result of the temperature sensor 25, the individual ink droplet ejection coating heads 19 are lowered in the Z-axis direction, and the nozzle plate 23 is brought into contact with the cooling plate 26. The cooling unit 9 is driven. Here, the detection result of the temperature sensor 25 is obtained by the control box 28, the mechanism for moving the inkjet head unit 5 above the cooling unit 9, and the mechanism for lowering the individual ink droplet ejection coating heads 19 in the Z-axis direction. Based on this, moving means for moving the ink droplet jet coating head 19 to a cooling position by the cooling unit 9 is formed.

  A plurality of ink supply tanks 29 are detachably attached inside the ink supply box 4. The individual ink supply tanks 29 store inks of different colors, and the individual ink supply tanks 29 are connected to the ink tanks 10 storing the same color inks through the supply pipes 30. When the ink in the ink replenishing tank 29 runs out, or when the amount is less than the set amount, the ink is replaced with a new ink replenishing tank 29.

  In such a configuration, control for preventing the nozzles 24 of the ink droplet ejection coating head 19 from being clogged with bubbles will be described with reference to the flowchart of FIG.

  The temperature sensor 25 constantly detects the temperature of the ink droplet ejection coating head 19, that is, the temperature of the ink in the ink droplet ejection coating head 19, and the detection result of the temperature sensor 25 is output to the control box 28 to eject the ink droplets. It is determined whether the temperature of the ink in the coating head 19 is equal to or higher than a set value (S1). Here, the step of detecting the temperature of the ink in the ink droplet jet application head 19 is executed.

  When it is determined that the measurement result of the temperature sensor 25 is equal to or greater than the set value (YES in S1), a step of cooling the ink in the ink droplet ejection coating head 19 is executed (S2). In this step, the cooling unit 9 is driven, the inkjet head unit 5 is moved above the cooling unit 9 along the guide plate 12, the ink droplet ejection coating head 19 is lowered in the Z-axis direction, and the nozzle plate 23 is recessed. 27a is inserted. When the nozzle plate 23 is inserted into the recess 27a and comes into contact with the cooling plate 26, the ink droplet ejection coating head 19 and the ink in the ink droplet ejection coating head 19 are cooled.

  By cooling the ink in the ink droplet ejection coating head 19, bubbles existing in the ink in the ink droplet ejection coating head 19 are melted in the ink or the bubbles in the ink are reduced.

  Therefore, by cooling the ink in the ink droplet ejection coating head 19 using the cooling unit 9, the bubbles in the ink can be eliminated or the large bubbles can be reduced. For this reason, bubbles are generated in the ink due to a rise in the temperature of the ink, and it is possible to prevent the non-ejection and ejection failure of the ink droplets E from the nozzle 24, which are caused by the generated bubbles clogging the nozzle 24.

  After the ink cooling by the cooling unit 9 is completed, the ink jet head unit 5 is moved to an ink discharge position (not shown), and so-called ink purge is performed in which the ink in the ink jet coating head 19 is discharged from the nozzle 24 (S3). ). This purging operation is performed by applying pressure to the ink supply path communicating with the ink chamber 20 and causing the ink in the ink droplet ejection coating head 19, particularly the ink in the ink chamber 20, to flow out from the nozzles 24. Due to this purge operation, the ink in the ink droplet ejection coating head 19 whose amount of melting of bubbles has increased due to cooling is discharged, and the bubbles that have melted in the ink return to the bubbles again as the temperature of the ink rises. Occurrence is prevented. Here, the step of discharging the cooled ink from the nozzles 24 of the ink droplet jet application head 19 is executed. When the ink is discharged, the bubbles in the ink are small, so that the bubbles can be discharged smoothly, and the amount of ink to be discharged can be reduced.

  After the step of discharging the ink in the ink jet coating head 19 is executed, the inkjet head unit 5 returns to the position for jetting ink droplets and stands by in preparation for jetting ink droplets from the nozzles 24.

  According to the present embodiment, the temperature of the ink in the ink droplet ejection coating head 19 can be maintained below the set temperature, thereby eliminating the bubbles in the ink in the ink droplet ejection coating head 19 or In addition, the bubbles in the ink in the ink droplet ejection coating head 19 can be reduced, and the non-ejection and ejection failure of the ink droplet E from the nozzle 24 caused by the bubbles present in the ink can be prevented.

  For cooling the ink in the ink droplet ejection coating head 19 and the ink in the ink droplet ejection coating head 19, heat transfer by contact with the cooled cooling unit 9 is used instead of heat transport by air blowing. As a result, it is possible to perform cooling while suppressing drying in the vicinity of the nozzle 24, and it is possible to prevent clogging of the nozzle 24 caused by drying.

1 is a perspective view showing a schematic configuration of a droplet spray coating apparatus according to an embodiment of the present invention. It is sectional drawing which shows schematic structure of the ink droplet spray application head with which the droplet spray application apparatus shown in FIG. 1 is provided. FIG. 2 is a front view showing a positional relationship during a cooling operation of a cooling unit and an ink droplet spray coating head provided in the droplet spray coating device shown in FIG. 1. It is a flowchart explaining the control which prevents that the nozzle of an ink droplet jet application head is blocked by air bubbles.

Explanation of symbols

DESCRIPTION OF SYMBOLS 9 ... Cooling unit, 19 ... Droplet spray coating head, 20 ... Liquid chamber, 24 ... Nozzle, 25 ... Temperature sensor

Claims (2)

A liquid droplet ejection coating head having a liquid chamber for storing liquid and a plurality of nozzles communicating with the liquid chamber, and ejecting liquid droplets from the nozzle;
A temperature sensor for detecting the temperature of the liquid in the droplet spraying application head;
A cooling unit for cooling the liquid in the droplet spraying application head;
Moving means for moving the droplet spraying application head to a cooling position by the cooling unit based on a detection result of the temperature sensor;
A droplet spray coating apparatus comprising: Detecting the temperature of the liquid in the droplet spraying application head;
Cooling the liquid when the temperature of the liquid in the droplet spraying application head is equal to or higher than a set value;
Discharging the cooled liquid from the nozzle of the droplet spraying application head;
A droplet spray coating method comprising:

Images