JP2006240158A - Liquid ejection method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form an ink meniscus at a proper position in an inkjet printer or the like. <P>SOLUTION: A liquid is sent from main tanks (1, 2, 3) to a sub tank (4) and stored in the sub tank. The liquid is sent from the sub tank to nozzle holes of an ejecting head (8). Liquid droplets are ejected towards a body to be applied (18) from a tip of the nozzle hole set upper than a level (17) of the sub tank. A pressure-feed means is set which pressure-feeds the liquid from the sub tank to the nozzle holes by sending a gas of a predetermined pressure into the sub tank. A meniscus of the liquid is formed at the tip of the nozzle hole by the pressure of the gas sent from the pressure-feed means. The meniscus of the liquid is formed at the tip of the nozzle hole by adjusting the pressure of the gas in the sub tank by the pressure-feed means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid ejection method and apparatus for ejecting an appropriate amount of liquid such as paint or ink.

  2. Description of the Related Art Conventionally, large-sized inkjet printers that are liquid ejection devices send liquid ink from a main tank to a sub-tank, send it from the sub-tank to an ink ejection head, and ink from a nozzle hole of the ink ejection head toward a coated object such as paper. The fine droplets are discharged. A main tank, a sub tank, and an ink discharge head are prepared for each printing color. The ink that has reached the nozzle holes of the ink discharge heads of the respective colors is ejected as fine droplets from the nozzle holes toward the coated body by a desired ejection method. By repeating the discharge of each droplet for each color, the ink is printed or applied as a desired pattern, pattern, or the like on the object (see, for example, Patent Documents 1, 2, 3, and 4).

  In an ink jet printer, in order to perform stable printing, coating, etc., it is necessary to supply ink from a sub tank to an ejection head so that an ink meniscus is formed at an appropriate position of the nozzle hole. Ink is supplied to the nozzle holes by so-called self-supply of ink using force (see, for example, Patent Documents 1 and 2).

  Some inkjet printers have an ink tank disposed in the vicinity of the ink discharge head, and the ink discharge head and the ink tank are integrated in a case. In this case, a negative pressure is generated in the ink supplied to the ink discharge head by providing a drop between the ink discharge head and the ink tank so that the ink does not flow out from the ink discharge head when recording is not performed by the ink discharge head. (For example, refer to Patent Document 3).

  In addition, according to the ink jet printer, it is possible to print on various materials such as paper, but recently it has been proposed to use an ink jet method for manufacturing a color filter used in a liquid crystal display device or the like (for example, (See Patent Document 4).

JP-A-7-52398 Japanese Patent Laid-Open No. 10-6521 JP-A-8-142342 JP 2000-221320 A

  According to the conventional ink jet printer, the ink is merely supplied from the sub tank to the tip of the nozzle hole by utilizing the capillary force of the nozzle hole, so that the ink is supplied when applying ink at a high speed (high frequency). However, there is a problem that productivity cannot be reduced because the coating cannot be performed at a low speed. This is particularly noticeable for large inkjet printers. It is conceivable to deal with such a problem by making the capillary tube thicker, but in this case, there arises a problem that the ink discharge head is enlarged. In addition, it is conceivable to increase the ink supply by installing an ink tank in the vicinity of the ink discharge head, but in this case, the replacement and maintenance of the ink tank deteriorates. Further, when patterning is performed by moving the ink ejection head, the ink level in the ink tank fluctuates, ink ejection becomes unstable, and patterning quality is degraded.

  Accordingly, an object of the present invention is to provide a liquid ejection method and apparatus that can solve the above-described problems.

  In order to solve the above-mentioned problem, the invention according to claim 1 is configured such that liquid is sent from the main tank (1, 2, 3) to the sub tank (4, 5, 6) and stored in the sub tank (4, 5, 6). Then, the liquid is sent from the sub tank (4, 5, 6) to the nozzle hole (7) of the discharge head (8), and the nozzle set above the liquid level (17) of the sub tank (4, 5, 6). In the liquid ejection device that ejects liquid droplets from the tip of the hole (7) toward the coated body (18), by sending a gas of a predetermined pressure into the sub tank (4, 5, 6), the sub tank (4, 5 , 6) is provided with a pumping means (28) for pumping liquid to the nozzle hole (7), and a liquid meniscus (23a) is provided at the tip of the nozzle hole (7) by the pressure of the gas sent from the pumping means (28). A liquid discharge device that is formed is employed.

  According to a second aspect of the present invention, in the liquid ejecting apparatus according to the first aspect, the position of the sub tank (4, 5, 6) is adjusted in a direction perpendicular to the liquid level (17), whereby the pressure feeding means ( A liquid ejection apparatus including a height adjusting means (48) for forming a liquid meniscus (23a) sent by (28) at the tip of the nozzle hole (7) is employed.

  According to a third aspect of the present invention, in the liquid ejection device according to the first or second aspect, the liquid is supplied from the main tank (1, 2, 3) to the sub tank (4, 5, 6). A liquid ejection apparatus including a liquid height holding means (16) for holding the liquid height in the sub tanks (4, 5, 6) constant is employed.

  According to a fourth aspect of the present invention, in the liquid ejection device according to any one of the first to third aspects, either one of filtration and deaeration is performed while circulating the liquid in the sub tank (4, 5, 6). A liquid ejection device provided with a circulation means (10) for performing both is employed.

  According to a fifth aspect of the present invention, in the liquid ejection device according to any one of the first to fourth aspects, the liquid is supplied from one sub tank (4, 5 or 6) to the plurality of ejection heads (8). A liquid ejecting apparatus adapted to be supplied is adopted.

  According to a sixth aspect of the invention, in the liquid ejection device according to any one of the first to fifth aspects, the display means (45) for observing the tip of the nozzle hole (7) of the ejection head (8). The provided liquid discharge apparatus is employed.

  According to a seventh aspect of the invention, the discharge head (8) of the liquid discharge apparatus according to any one of the first to sixth aspects is mounted on an XY plotter, and the discharge head (8) is driven by driving the XY plotter. A liquid ejection apparatus is employed in which a predetermined pattern is formed on the surface of the coated body (18) by ejecting the liquid from the nozzle hole (7) toward the coated body (18).

  In the invention according to claim 8, the liquid is sent from the main tank (1, 2, 3) to the sub tank (4, 5, 6) and stored in the sub tank (4, 5, 6). 5, 6) liquid is sent to the nozzle hole (7) of the discharge head (8), and the tip of the nozzle hole (7) set above the liquid level (17) of the sub tank (4, 5, 6). In the liquid discharge method for discharging liquid droplets from the sub tank (4, 5, 6) to the coated body (18), a nozzle hole is formed from the sub tank (4, 5, 6) by sending a gas of a predetermined pressure into the sub tank (4, 5, 6). A liquid discharge method is adopted in which liquid is pumped to (7) and a meniscus (23a) of this liquid is formed at the tip of the nozzle hole (7).

  According to a ninth aspect of the present invention, in the liquid ejection method according to the eighth aspect, the position of the sub tanks (4, 5, 6) is adjusted in a direction perpendicular to the liquid surface (17), whereby a liquid meniscus ( A liquid discharge method is adopted in which 23a) is formed at the tip of the nozzle hole (7).

  The invention according to claim 10 is the liquid discharge method according to claim 8 or claim 9, wherein the liquid is supplied from the main tank (1, 2, 3) to the sub tank (4, 5, 6). A liquid discharge method is used in which the liquid height in the sub tanks (4, 5, 6) is kept constant.

  The invention according to claim 11 is the liquid ejection method according to any one of claims 8 to 10, wherein one of filtration and deaeration is performed while circulating the liquid in the sub tank (4, 5, 6). A liquid discharge method that performs both is adopted.

  According to a twelfth aspect of the present invention, in the liquid discharge method according to any one of the eighth to eleventh aspects, liquid is supplied from one sub tank (4, 5 or 6) to a plurality of discharge heads (8). A liquid discharging method to be supplied is adopted.

  According to the first or eighth aspect of the invention, the pressure of the gas in the sub-tank (4, 5, 6) is adjusted by the pressure feeding means (28), so that the liquid meniscus is formed at the tip of the nozzle hole (7). (23a) can be formed. Accordingly, the liquid supplied to the discharge head (8) by the capillary force is always accurately distributed to the tip of the nozzle hole (7), and an appropriate amount of liquid is always directed to the coated body (18) without involving air. It is possible to form a coated film uniformly and accurately on the substrate (18) by discharging, and even when applying and printing a liquid at high speed (high frequency), it also has a large area Even in the case of coating and printing, it is possible to reliably follow the supply of the liquid without increasing the size of the discharge head, and thus the productivity can be improved. Further, since the liquid can be supplied to the discharge head without installing a liquid tank in the vicinity of the discharge head, the discharge of the liquid is stabilized and the deterioration of the quality of the coating film is prevented.

  According to the invention of claim 2 or claim 9, a predetermined amount of liquid is pumped into the nozzle hole (7) of the discharge head (8) by the pumping means (28), and then the height adjusting means (48). The sub tanks (4, 5, 6) can be moved in a direction perpendicular to the liquid surface to form a liquid meniscus (23a) at the tip of the nozzle hole (7). Therefore, the position of the meniscus (23a) can be adjusted more easily. In the case of discharging a plurality of types of liquids, the gas pressure-adjusted by one pressure-feeding means (28) is sent to all the liquid sub-tanks (4, 5, 6), and the meniscus resulting from the difference in liquid viscosity and the like. The displacement of the position (23a) is eliminated by adjusting the liquid height by the height adjusting means (48), whereby all the meniscus (23a) of the liquid can be formed at the tip of the nozzle hole (7). Therefore, when discharging a plurality of types of liquids, it is sufficient to provide only one expensive pressure adjusting device, and the liquid discharging apparatus can be simplified and reduced in price.

  According to the invention which concerns on Claim 3 or Claim 10, regardless of the consumption of the liquid in a subtank (4,5,6), a liquid height can always be kept constant. Therefore, the liquid meniscus (23a) can be appropriately formed at the tip of the nozzle hole (7) of the discharge head (8).

  According to the invention of claim 4 or claim 11, foreign matter such as dust in the liquid can be removed to prevent clogging of the nozzle hole (7), and bubbles in the liquid can be removed. It is possible to prevent the liquid discharge amount from the nozzle hole (7) from fluctuating.

  According to the invention which concerns on Claim 5 or Claim 12, even when it is a case where the same kind of liquid is apply | coated over a wide range with respect to a to-be-coated body (18), several discharge head (8) is used. Thus, the same amount of liquid can be discharged simultaneously from these.

  According to the invention of claim 6, while observing the position and state of the liquid meniscus (23a) formed at the tip of the nozzle hole (7), the pressure adjustment of the pumping means (28) or the sub tanks (4, 5) , 6) can be adjusted appropriately.

  According to the invention which concerns on Claim 7, a desired pattern can be accurately formed in the surface of to-be-coated bodies (18), such as paper and a board, by pattern formation apparatuses, such as an inkjet printer.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  An apparatus for carrying out this liquid ejection method is used, for example, for manufacturing a color filter of a liquid crystal display device. As shown in FIGS. 1 to 3, liquid red (R), green (G), blue ( B) main tanks 1, 2, 3 storing ink of each color, sub-tanks 4, 5, 6 for each color storing ink sent from the main tanks 1, 2, 3, and sub-tanks 4, 5, 5, respectively. 6 and an ejection head 8 having a nozzle hole 7 for ejecting ink sent from 6.

  The main tanks 1, 2, and 3 are filled with liquid color inks. A liquid level sensor 9 for detecting the lower limit of the liquid level is detachably attached to each main tank 1, 2 and 3. When the liquid level sensor 9 detects the lower limit of the liquid level in the main tanks 1, 2, 3, ink is replenished in the main tanks 1, 2, 3, or other main tanks 1, 2, 2 filled with ink. Exchanged for 3. The liquid level sensor may be fixed and the main tank may be moved up and down.

  A circulation path 10 that constantly circulates ink in the sub tanks 4, 5, 6 is connected to each of the sub tanks 4, 5, 6. The circulation path 10 is formed by a tube, for example.

  In FIG. 1, only the circulation path for R ink, the sub tank, and the like are shown, but other G and B inks are also provided in the same manner.

  On the circulation path 10, a pump 11 such as a tube pump that sends ink in one direction, a filter 12 that removes foreign matters in the ink, a deaeration filter 13 a that removes bubbles in the ink, and the like are arranged. A conduit 14 drawn from the main tanks 1, 2, 3 is connected to the upstream side of the pump 11 in the circulation path 10. The conduit 14 is also formed of a tube similar to the circulation path 10. Valves 15 a, 15 b, 15 c such as electromagnetic valves are provided on each tube of the three-way road by connecting the conduit 14 to the circulation path 10. When the first and second valves 15a, 15b on the circulation path 10 are opened, the third valve 15c on the conduit 14 is closed, and the pump 11 is driven, the ink in each sub-tank 4, 5, 6 is transferred to each circulation path. The inside of the ink 10 flows in the direction of the arrow and continuously circulates, whereby foreign matter in the ink is removed by the filter 12, and bubbles in the ink are removed by the deaeration filter 13a. As a result, the nozzle holes 7 of the ejection head 8 are prevented from being clogged with foreign matter, and bubbles are prevented from being mixed into the nozzle holes 7.

  As shown in FIG. 1, the liquid ejection apparatus includes a liquid height holding unit that keeps the liquid height in the sub tanks 4, 5, and 6 constant. The liquid height holding means has a liquid level sensor 16 attached to each of the sub tanks 4, 5, 6. When the ink in the sub tank 4 is ejected and consumed from the ejection head 8 and the liquid level 17 falls in the sub tank 4, the first valve 15a on the circulation path 10 is closed by the signal from the liquid level sensor 16, and the second and second The third valves 15b and 15c are opened, and the ink in the main tank 1 is replenished into the sub tank 4 by the pump 11. When the ink level 17 in the sub-tank 4 reaches a predetermined height, a signal from the level sensor 16 opens the first valve 15a on the circulation path 10, closes the third valve 15c, and the main tank 1 The ink flow from is blocked. Thus, whenever the ink level 17 drops from the main tank 1 to the sub tank 4, the ink is replenished and the liquid level in the sub tank 4 is kept constant. The other sub tanks 5 and 6 are operated in the same manner, and the ink liquid height in each of the sub tanks 5 and 6 is kept constant.

  Although only one discharge head 8 can be provided for each sub-tank 4, in this embodiment, a plurality, specifically five, are provided. The five discharge heads 8 are arranged so as to cross the glass substrate 18 of the color filter. From the sub tank 4, a conduit 19 made of a tube extends toward each discharge head 8. As a result, the same type of liquid is applied over the entire surface of the substrate having a large area such as the glass substrate 18 of the color filter. An electromagnetic valve 20 is provided on each conduit 19 extending from the sub tank 4 toward each discharge head. By opening these solenoid valves 20, ink is supplied from the sub tank 4 to the nozzle holes 7 of the ejection head 8. The discharge heads are similarly assigned to the other sub tanks 5 and 6.

  As shown in FIG. 3A, each discharge head 8 includes a tunnel-shaped liquid reservoir chamber 21, an injection port 22 that communicates with the liquid reservoir chamber 21, and a number of nozzle holes 7 that also communicate with the liquid reservoir chamber 21. Is formed. A conduit 19 extending from the sub-tank 4 is connected to the injection port 22, and ink that has passed from the sub-tank 4 through the conduit 19 fills the liquid reservoir chamber 21. For example, 128 nozzle holes 7 are formed for each ejection head 8, and as shown in FIG. 3B, the ink 23 is accumulated in the nozzle holes 7, and a meniscus 23 a is formed at the tip of the nozzle holes 7. FIG. 3B shows the position and shape of a normal meniscus 23a. When the meniscus 23a protrudes in a spherical shape from the tip of the nozzle hole 7, the discharge amount of the ink 23 becomes excessive and deepens from the tip of the nozzle hole 7. When it is formed at a location, the discharge amount is insufficient. The ink 23 accumulated in the nozzle hole 7 is ejected as a fine droplet from the tip of the nozzle hole 7 by a signal from a control unit (not shown) of the liquid ejection device. As a means for firing the ink 23, there are a piezo method, a thermal ink jet method, and the like, and a desired firing method is adopted.

  As shown in FIG. 1, the discharge head 8 has its nozzle hole 7 at the tip from the ink liquid level 17 in the sub tank 4 so that the meniscus 23 a of the ink 23 is formed at the position and shape shown in FIG. A pressure feeding means is provided that is disposed so as to be at the position of the height H and that sends air, which is a gas of a predetermined pressure, into the sub tank 4 to eliminate the head (water head) difference of the height H. In this case, the height H is made uniform for all color inks.

  The pumping means has an air circuit device 24 shown in FIG. The air circuit device 24 depressurizes compressed air sent from a compressed air source 25 such as a compressor and filtered by a filter 26 within a predetermined range by a regulator 27, finely adjusts the pressure by a pressure controller 28, and further depressurizes all the sub tanks 4. 5 and 6 are sent. The pressure controller 28 includes a servo valve or the like. According to this pressure controller 28, pressure adjustment is possible with an accuracy within 0.1 kPa (10 mm water column) in the range of 0 to 20 kPa. The pressure controller 28 can be provided for each of the ink sub-tanks 4, 5, 6 of each color (R, G, B), but in this embodiment, only one is provided, and this one pressure controller 28 is provided. The conduits 29, 30, and 31 branch to the sub-tanks 4, 5, and 6. A buffer tank 32 and electromagnetic valves 33 and 34 are provided on the conduits 29, 30 and 31 from the pressure controller 28 to the sub-tanks 4, 5 and 6.

  In addition, in the air circuit device 24, as shown in FIG. 2, detour conduits 35 and 36 that bypass the pressure controller 28, the buffer tank 32, and the like from the upstream side of the pressure controller 28 to the sub tanks 4, 5, and 6, respectively. 37, an electropneumatic converter 38 is provided on the upstream side before the bypass conduits 35, 36, and 37 are branched, and electromagnetic valves 39 and 40 are provided on the bypass conduits 35, 36, and 37, respectively. The bypass conduits 35, 36, and 37 are used when initially filling ink from the sub-tanks 4, 5, and 6 into the nozzle holes 7 of the ejection head 8. In the air circuit device 24, a vacuum pump 41 for degassing the degassing filters 13a, 13b, 13c is provided. A regulator 43, a trap 44, and the like are provided on the suction pipe 42 extending from the degassing filters 13a, 13b, and 13c to the vacuum pump 41. The degassing filters 13b and 13c are for degassing G ink and B ink, respectively.

  In the air circuit device 24 shown in FIG. 2, the solenoid valve 39 on the bypass conduits 35, 36, and 37 is opened, the solenoid valve 33 on the conduits 29, 30, and 31 from the pressure controller 28 is closed, and the solenoid valve 34 is opened. When high-pressure compressed air flows from the compressed air source 25 into the sub tanks 4, 5, 6 through the electropneumatic converter 38, ink rapidly flows from the sub tanks 4, 5, 6 to the discharge heads 8, At the same time as it flows into the nozzle hole 7, the air in the nozzle hole 7 is discharged from the tip of the nozzle hole 7. Next, the solenoid valve 39 on the bypass conduits 35, 36, and 37 is closed, the solenoid valve 40 is opened, and the high-pressure air in the bypass conduits 35, 36, and 37 is exhausted to the atmosphere. The electromagnetic valves 33 on the 30 and 31 are opened, and relatively low pressure air whose pressure is adjusted by the pressure controller 28 is sent into the sub tanks 4, 5 and 6. The low-pressure air causes the ink in the sub-tanks 4, 5 and 6 to rise by the height H shown in FIG. 1, flows into the nozzle hole 7 of the discharge head 8, and reaches the tip of the nozzle hole 7 as shown in FIG. A meniscus 23a is formed.

  In order to form the meniscus 23a at the tip of the nozzle hole 7 as shown in FIG. 3B, this liquid discharge device has a display device 45 for observing the tip of the nozzle hole 7 of the discharge head 8 as shown in FIG. Provided. The display device 45 includes a camera 46 and a monitor 47 for photographing a part or the entire tip of the nozzle hole 7 in the ejection head 8. The operator adjusts the pressure with the pressure controller 28 while observing the tip of the nozzle hole 7 on the monitor 47, and the pressure adjustment is completed when the meniscus 23a as shown in FIG. 3B is formed.

  It may be difficult to form the meniscus 23a at the tip of the nozzle hole 7 only by the pressure feeding means. In particular, when the compressed air obtained by one pressure controller 28 is supplied to all the sub-tanks 4, 5, 6, the ink of a certain color can form the meniscus 23 a at the tip of the nozzle hole 7. In the case of the ink of the color, the meniscus 23a may be formed in the deep part of the nozzle hole 7. Such a phenomenon is considered to occur due to differences in ink viscosity and density. As shown in FIG. 1, this liquid ejection device is a means for allowing the meniscus 23 a to move to the tip of the nozzle hole 7 when the meniscus 23 a cannot be formed at an appropriate position by the pressure feeding means. A height adjusting device 48 is provided.

  The height adjusting device 48 includes an arm 49 fixed substantially horizontally to each of the sub-tanks 4, 5, 6, and a feed screw rod 50 extending in the vertical direction and screwed into a female screw (not shown) of the arm 49. To do. The feed screw rod 50 is rotatably held by a frame (not shown) of the liquid ejecting apparatus. When the feed screw rod 50 is rotated in either direction, the sub tank 4 rises or falls in a direction perpendicular to the liquid surface 17, and the ink meniscus 23 a sent by the pressure feeding means moves in the nozzle hole 7. To do. The operator turns the feed screw rod 50 while observing the tip of the nozzle hole 7 on the monitor 46 and adjusts the height of the sub tank 4 so that the meniscus 23a reaches the tip of the nozzle hole 7 as shown in FIG. Then the pressure adjustment is completed. Such height adjustment is performed for the sub tanks 4, 5, and 6 of all the inks in which the position defect has occurred in the meniscus 23a.

  Next, the operation of the liquid ejection apparatus having the above configuration will be described.

  (1) In manufacturing the color filter, first, in the air circuit device 24 shown in FIG. 2, the electromagnetic valve 39 on the bypass conduits 35, 36, and 37 is opened, and the high pressure is supplied from the pressurized air source 25 via the electropneumatic converter 38. Compressed air is supplied into all the sub tanks 4, 5, 6. By this compressed air, ink rapidly flows from each of the sub tanks 4, 5, 6 to each discharge head 8 shown in FIG. The ink flows from the injection port 22 into the liquid reservoir chamber 21 in each discharge head 8 and then into a large number of nozzle holes 7, and simultaneously removes air from the nozzle holes 7.

  (2) The solenoid valve 39 on the bypass conduits 35, 36, and 37 is closed, the solenoid valve 40 is opened to release high-pressure compressed air into the atmosphere, and then the solenoids on the conduits 29, 30, and 31 on the pressure controller 28 side. The valve 33 is opened, and relatively low pressure air whose pressure is adjusted by the pressure controller 28 is sent into all the sub tanks 4, 5, 6. The low-pressure air causes the ink in the sub-tanks 4, 5 and 6 to rise by the height H shown in FIG. 1, flows into the nozzle hole 7 of the discharge head 8, and reaches the tip of the nozzle hole 7 as shown in FIG. A meniscus 23a is formed.

  When the meniscus 23a is formed at the tip of the nozzle hole 7, the tip of the nozzle hole 7 of the discharge head 8 is observed by the display device 45 as shown in FIG. At this time, the glass substrate 18 of the color filter has not been supplied yet. The operator adjusts the pressure with the pressure controller 28 shown in FIG. 2 while observing the tip of the nozzle hole 7 on the monitor 47, and adjusts the pressure when the meniscus 23a is formed at the tip of the nozzle 7 as shown in FIG. Complete.

  (3) The meniscus 23 a may not be formed at the tip of the nozzle hole 7 only by the air adjusted by the pressure controller 28, and a certain color of ink can form the meniscus 23 a at the tip of the nozzle hole 7. However, for other color inks, the meniscus 23 a may be formed in the deep part of the nozzle hole 7. In that case, the meniscus 23a is moved to the tip of the nozzle hole 7 by operating the height adjusting device 50 shown in FIG.

  That is, the operator turns the feed screw rod 50 while observing the tip of the nozzle hole 7 on the monitor 47 to adjust the heights of the sub tanks 4, 5, and 6, and the meniscus 23a is moved to the nozzle hole as shown in FIG. When the tip of 7 is reached, rotation of the feed screw rod 50 is stopped and pressure adjustment is completed. Such height adjustment is performed for the sub-tanks 4, 5, and 6 of all the inks in which the position defect has occurred in the meniscus 23a.

  Thus, the preparation for printing or applying each ink on the glass substrate 18 of the color filter is completed.

  (4) As shown in FIG. 1, the glass substrate 18 of the color filter is directly opposed to the nozzle hole 7 of the ejection head 8 and the ejection head 8 and the glass substrate 18 are moved relative to each other, while the fineness of ink from the ejection head 8 is achieved. Droplets are fired onto the glass substrate 18. In each nozzle hole 7 of the ejection head 8, the ink is supplied so as to form a meniscus 23 a at the tip of the nozzle hole 7, so that the ink becomes an appropriate amount of liquid droplets without entraining air from the tip of the nozzle hole 7. Then, it is discharged toward the glass substrate 18 which is an object to be coated. As a result, a coating film made of R, G, B ink is uniformly and accurately formed on the glass substrate 18.

  (5) In addition, while the ink is ejected from each ejection head 8, the ink in the sub tanks 4, 5 and 6 flows in the direction of the arrow by the drive of the pump 11 on the circulation path 10 shown in FIG. During the circulation, foreign matter in the ink is removed by the filter 12, and bubbles in the ink are removed by the degassing filters 13a, 13b, and 13c. Thereby, clogging of the nozzle hole 7 of the ejection head 8 is prevented, and mixing of bubbles into the nozzle hole 7 is prevented.

  (6) Also, by ejecting ink from each ejection head 8, the ink in the sub-tanks 4, 5, 6 is consumed and the liquid level 17 falls, but the liquid level sensor 16 detects this drop in the liquid level 17. To do. The signal from the liquid level sensor 16 closes the first valve 15 a on the circulation path 10, opens the second and third valves 15 b, 15 c, and supplies the ink in the main tanks 1, 2, 3 to the sub tank by the pump 11. Refill in 4, 5 and 6. When the ink level 17 in the sub-tanks 4, 5 and 6 reaches a predetermined height, a signal from the level sensor 16 opens the first valve 15a on the circulation path 10 and closes the third valve 15c. The flow of ink from the main tanks 1, 2, 3 is blocked. Thereby, the liquid height in the sub tanks 4, 5, 6 is always kept constant, and the meniscus 23 a is always formed in a normal position in the ejection head 8.

  The ejection head 8 is mounted on an ink jet printer type XY plotter shown in FIG. 4 which is a pattern forming apparatus, for example, while scanning on the glass substrate 18 which is an object to be coated arranged in the XY plotter in the XY direction. Ink is ejected from the nozzle holes 7 shown in FIG. 7 toward the glass substrate 18 to form a pattern such as a color filter on the surface of the glass substrate 18.

  This ink jet printer type XY plotter is a color filter manufacturing apparatus. As shown in FIG. 4, two X-axis rails 53 are provided with a surface plate 52 on a base portion 51 and extend parallel to each other on the surface plate 52. , 53 are provided. A moving table 54 is mounted on the X-axis rails 53 and 53, and the moving table 54 is configured to be capable of reciprocating along the X-axis rails 53 and 53 by driving a stage drive mechanism (not shown).

  A rotating table 55 and a stage 56 are sequentially stacked on the moving table 54, and the stage 56 can be rotated with respect to the moving table 54 by rotating the rotating table 55 by driving a rotation driving mechanism (not shown). . On the stage 56, for example, a 2 m square glass substrate 18 is placed. The stage 56 includes a vacuum mechanism (not shown) and can suck the glass substrate 18 placed thereon.

  Therefore, the glass substrate 18 can be reciprocated along the X-axis rails 53 and 53 by driving the stage driving mechanism, and the moving table is driven by rotating the rotary table 55 by driving a rotary driving mechanism (not shown). 54 can be rotated.

  A gate-shaped support arm 57 is installed on the surface plate 52 so as to straddle the X-axis rails 53, 53, the moving table 54, the rotary table 55, the stage 56, and the glass substrate 18. Two Y-axis rails 58 extending in a direction orthogonal to the X-axis rails 53 are fixed to the horizontal portion 57 a at the upper end of the support arm 57.

  A Y-direction stage drive mechanism 59 is attached to the Y-axis rail 58, and the R, G, and B color ink ejection heads 8 are supported under the Y-direction stage drive mechanism 59 via a rotating unit 60. The ejection head 8 can be moved in the Y-axis direction by the Y-direction stage drive mechanism 59 and can be rotated on the horizontal plane by driving the rotating unit 60.

  One end of a conduit 19 that is an ink supply tube for supplying R, G, and B3 inks is connected to the ejection head 8, and the other end of the conduit 19 stores R, G, and B3 inks, respectively. Connected to sub tanks 4, 5, 6. The ejection head 8 is, for example, a piezo drive type, and the ink supplied from the sub tanks 4, 5, 6 through the conduit 19 is ejected from the ejection head 8.

  An X direction stage drive mechanism and various sensors are provided in the moving table 54, and the moving table 54 is connected to the control unit 62 through a signal line 61.

  The glass substrate 18 is transported in the XY direction by the ink jet printer type XY plotter having the above configuration, and ink is ejected from the ejection head 8 to the surface of the transported glass substrate 18, and a predetermined color filter or the like is applied to the surface of the glass substrate 18. Pattern is formed.

  The present invention is not limited to the above-described embodiment. In the above-described embodiment, the case where three color liquid inks are applied to the substrate of the color filter has been described. However, the present invention is not limited to one color or four colors or more. The present invention can also be applied to the case of applying and printing ink, the case of applying and printing a liquid other than ink, and the case of applying and printing on an applied material other than the substrate of the color filter.

It is a schematic block diagram which shows an example of the liquid discharge apparatus which concerns on this invention. It is a block diagram which shows an example of the air circuit in the pressure sending means of the liquid discharge apparatus shown in FIG. Fig. (A) is a schematic longitudinal sectional view of the ejection head, and Fig. (B) is an enlarged view of portion B in Fig. (A). The state in which the meniscus is formed in an appropriate position and shape in one nozzle hole is shown. Show. It is a perspective view of the pattern formation apparatus provided with the liquid discharge apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2, 3 ... Main tank 4, 5, 6 ... Sub tank 7 ... Nozzle hole 8 ... Discharge head 10 ... Circulation path 16 ... Liquid level sensor 17 ... Liquid level 18 ... Glass substrate 23a ... Meniscus 28 ... Pressure controller 45 ... Display Device 48 ... Height adjustment device

Claims (12)

  Liquid is sent from the main tank to the sub tank and stored in the sub tank, and the liquid is sent from the sub tank to the nozzle hole of the discharge head, from the tip of the nozzle hole set above the liquid level of the sub tank toward the object to be coated. In a liquid ejection apparatus that ejects liquid droplets, by supplying a gas of a predetermined pressure into a sub tank, a pressure feeding means for pumping liquid from the sub tank to the nozzle hole is provided, and the tip of the nozzle hole is formed by the pressure of the gas sent from the pressure feeding means A liquid discharge apparatus characterized in that a liquid meniscus is formed.   2. The liquid ejection apparatus according to claim 1, further comprising: height adjusting means for forming a meniscus of the liquid sent by the pressure feeding means at a tip of the nozzle hole by adjusting the position of the sub tank in a direction perpendicular to the liquid surface. A liquid ejecting apparatus comprising the liquid ejecting apparatus.   3. The liquid discharge apparatus according to claim 1, further comprising a liquid height holding means for replenishing liquid from the main tank to the sub tank and holding the liquid level in the sub tank constant. apparatus.   4. The liquid discharge apparatus according to claim 1, further comprising a circulation unit that performs one or both of filtration and deaeration while circulating the liquid in the sub tank. .   5. The liquid discharge apparatus according to claim 1, wherein the liquid is supplied to a plurality of discharge heads from one sub tank.   6. The liquid ejection apparatus according to claim 1, further comprising display means for observing the tip of the nozzle hole of the ejection head.   The discharge head of the liquid discharge apparatus according to any one of claims 1 to 6 is mounted on an XY plotter, and discharges liquid from a nozzle hole of the discharge head toward an object to be coated as the XY plotter is driven. A liquid ejection apparatus characterized in that a predetermined pattern is formed on the surface of an object to be coated.   Liquid is sent from the main tank to the sub tank and stored in the sub tank, and the liquid is sent from the sub tank to the nozzle hole of the discharge head, from the tip of the nozzle hole set above the liquid level of the sub tank toward the object to be coated. In the liquid discharge method for discharging liquid droplets, a liquid of a predetermined pressure is sent into the sub tank so that the liquid is pumped from the sub tank to the nozzle hole, and a meniscus of this liquid is formed at the tip of the nozzle hole. A liquid discharge method.   9. The liquid ejection method according to claim 8, wherein a liquid meniscus is formed at the tip of the nozzle hole by adjusting the position of the sub tank in a direction perpendicular to the liquid surface.   10. The liquid discharge method according to claim 8, wherein the liquid is replenished from the main tank to the sub tank to keep the liquid height in the sub tank constant.   11. The liquid discharge method according to claim 8, wherein one or both of filtration and deaeration is performed while circulating the liquid in the sub tank.   12. The liquid discharge method according to claim 8, wherein the liquid is supplied from a single sub tank to a plurality of discharge heads.

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