JP4802835B2 - Droplet discharge head cleaning device and droplet discharge device including the same - Google Patents

Description

  The present invention relates to a droplet discharge head cleaning device and a droplet discharge device including the same, and more particularly to a droplet discharge head cleaning device that discharges coating liquid in which solid fine particles are mixed and dispersed as droplets. .

  Since the ink jet method can eject droplets from the orifice when necessary, an arbitrary pattern can be easily formed, and since there are few solutions that are wasted and discharged, it is advantageous from the environmental viewpoint.

  As an application example of the ink jet type droplet discharge device, there is a color filter manufacturing technique for a liquid crystal display device. Since this color filter is generally manufactured by repeating many photolithography processes such as development, exposure, and etching for each of the three colors R, G, and B, many processes are required. On the other hand, when manufacturing a color filter by the ink jet method, each ink jet head is filled with inks of three colors R, G, and B, and only a necessary amount is ejected to a necessary position and cured. Can be manufactured.

  Further, in the liquid crystal display device, in order to keep the interval between the two liquid crystal substrates constant, a particulate spacer is disposed between the liquid crystal substrates. Conventionally, spacers were sprayed on the liquid crystal substrate using a spray-type spraying device, etc., but this method tends to spray the spacers non-uniformly, so that the distance between the liquid crystal substrates cannot be kept constant and the display quality deteriorates. Invite.

  In order to eliminate such disadvantages, a spacer is attached by discharging a coating liquid containing a spacer onto a liquid crystal substrate with an ink jet type droplet discharge device. According to this droplet discharge device, the spacer can be arranged at a predetermined position, and if a discharge head having a large number of orifices is used, the spacer can be landed at a large number of designated positions at the same time. It is good.

  There are two types of ink-jet methods: an on-demand ink-jet method and a continuous ink-jet method, and the former has features such that droplets can be landed with high definition and the system is simple. The on-demand ink jet method requires a discharge head cleaning device that cleans the vicinity of the orifice. With this cleaning device, it is necessary to remove the coating liquid having a high viscosity by drying or the like, the modified coating liquid, or the foreign matter adhering to the vicinity of the orifice to ensure the stability of droplet discharge.

  With regard to the discharge head cleaning device, there are proposals described in, for example, Patent Documents 1 and 2 below. In the cleaning device described in Patent Document 1, the tip opening of the suction nozzle is arranged with a slight gap with respect to the outer surface where the orifice of the ejection head is formed. By sucking air from the negative pressure generation source through the suction nozzle, a suction air flow is formed near the tip opening of the suction nozzle, and the ink in the orifice is sucked and discharged by this suction air flow.

  In the cleaning device described in Patent Document 2, a spacer plate is attached to the orifice forming surface on which the orifice of the ejection head is formed along the row of orifices, and a part of the suction opening of the suction nozzle is brought into contact with the spacer plate. Thereby, a gap corresponding to the thickness of the spacer plate is formed between the orifice forming surface and the suction opening of the suction nozzle.

The suction nozzle is provided with a cleaning liquid discharge opening around the suction opening, and the cleaning liquid is drawn out from the cleaning liquid discharge opening by sucking from the suction opening of the suction nozzle by a negative pressure generation source. The cleaning liquid is brought into contact with the periphery of the orifice, and the contact cleaning liquid is sucked and collected from the suction nozzle.
JP 2003-039710 A JP-A-2005-131969

  By the way, in the cleaning device described in Patent Document 1, the ink in the orifice tends to be dried and increased in viscosity by the air flow formed by suction, and the foreign matter fixed to the orifice forming surface of the ejection head by the simple air flow. It is difficult to remove completely. Further, in the case of a discharge head that discharges a coating liquid in which solid fine particles are dispersed, even though the liquid (dispersion liquid) can be sucked and removed by a suction nozzle, solid fine particles having a specific gravity larger than that remain in the orifice. Increase in viscosity is promoted in the orifice, and the droplet discharge amount of the discharge head varies after cleaning.

  In the cleaning device described in Patent Document 2, since the spacer plate is attached in the vicinity of the orifice row, a corner is formed between the orifice forming surface and the edge of the spacer plate. For this reason, the fixed particles accumulate at the corners during the suction operation and remain as they are, and the droplet ejection direction may change due to the influence.

  An object of the present invention is to provide a cleaning device for a droplet discharge head having a high cleaning effect and a droplet discharge device including the same.

In order to achieve the above object, the present invention comprises a cleaning nozzle,
Cleaning liquid supply means for supplying a cleaning liquid to the periphery of the front end opening of the cleaning nozzle;
A suction means for sucking the waste liquid circulation space inside the cleaning nozzle,
The front end opening of the cleaning nozzle is opposed to the orifice forming surface of the liquid droplet discharge head in which the orifice for discharging liquid droplets is formed, and the cleaning liquid is supplied around the front end opening of the cleaning nozzle by the cleaning liquid supply means. However, a cleaning device for a droplet discharge head that sucks the waste liquid circulation space of the cleaning nozzle by the suction means, cleans the orifice forming surface of the droplet discharge head, and discharges the waste liquid through the waste liquid circulation space. To do.

And the first means of the present invention is :
A plurality of grooves inclined in a fixed direction with respect to the central direction of the cleaning nozzle are formed in the circumferential direction of the tip of the cleaning nozzle.

According to a second means of the present invention, in the first means,
The cleaning nozzle has a double tube structure of an inner tube and an outer tube,
A cleaning liquid circulation space is formed between the inner pipe and the outer pipe, and the cleaning liquid supply means is connected to the cleaning liquid circulation space,
The waste liquid circulation space is formed inside the inner pipe,
The groove is formed at least at the tip of the inner tube.

A third means of the present invention is the first or second means,
The droplet discharge head is a droplet discharge head that discharges droplets in which solid fine particles are mixed and dispersed.

The fourth means of the present invention is:
A droplet discharge head in which an orifice for discharging droplets is formed;
A moving means for relatively moving an adherend for landing a droplet discharged from the droplet discharge head and the droplet discharge head;
In a droplet discharge device provided with a cleaning device provided at a standby position of the droplet discharge head,
The cleaning device is a cleaning device of the first to third means.

  The present invention is configured as described above and can provide a cleaning device for a droplet discharge head having a high cleaning effect and a droplet discharge device including the same.

  Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 9 is a schematic configuration diagram of the entire droplet discharge apparatus according to the embodiment of the present invention, and FIG. 10 is a partially enlarged cross-sectional view of a discharge head mounted on the apparatus.

  As shown in FIG. 9, in the droplet discharge device, a substrate holder 2 holding the mother substrate 1 is installed so as to be able to reciprocate in the Y direction, and an ejection head 3 is installed above the mother substrate 1 so as to be able to reciprocate in the Z direction. Has been.

  The discharge head 3 is supported by the movement guide 4 in the X direction via the movement guide 5 in the Z direction, and is connected to a solution tank (not shown) via a flexible solution supply pipe 6. A head cleaning device 7 is provided at the standby position of the ejection head 3.

  The discharge head 3 has a cross-sectional structure as shown in FIG. In the figure, 11 is an orifice, 12 is a pressurizing chamber, 13 is a diaphragm, 14 is a piezoelectric element, 15a and 15b are signal input terminals, 16 is a piezoelectric element fixing plate, 17 is a common coating liquid supply pipe 18 and a pressurizing chamber. 12 is a restrictor that controls the flow of the coating liquid into the pressurizing chamber 12, 18 is a common coating liquid supply pipe, 19 is a filter, 20 is an adhesive that bonds the diaphragm 13 and the piezoelectric element 14, and 21 is The restrictor plate, 22 is a pressurizing chamber plate, 23 is an orifice plate, 24 is a support plate for reinforcing the diaphragm 13, 25 is a housing, and 26 is a filter plate.

  The coating liquid in which the spacer fine particles are mixed and dispersed flows from the upstream side to the downstream side of the ejection head 3, passes through the filter 19 in the middle of the common coating liquid supply pipe 18, and then the restrictor 17, the pressure chamber 12, and the orifice. It flows in order of 11. The piezoelectric element 14 expands and contracts when a voltage is applied between the signal input terminals 15a and 15b, and returns to its original state when no voltage is applied. Due to the deformation of the piezoelectric element 14, pressure is applied to the coating liquid in the pressurizing chamber 12, and droplets containing spacer fine particles are discharged from the orifice 11.

  The ejection head 3 can move in the X direction and the Z direction along the X direction movement guide 4 and the Z direction movement guide 5 as shown in FIG. 9, and the mother substrate 1 on the substrate holder 2 can move in the Y direction. Based on a signal from a head drive control unit (not shown), a coating liquid containing spacer fine particles can be discharged to an arbitrary position on the mother substrate 1. The movement of the ejection head 3 in the X direction and the Z direction and the movement of the mother substrate 1 in the Y direction are each performed by a motor (not shown) with an encoder.

  FIG. 11 is a plan view showing the relationship between the ejection head 3 and the color filter substrate 27 for liquid crystal to which spacers are attached. The substrate 27 is formed in a plurality of sections at a predetermined interval on a large mother substrate 1 (see FIG. 9) made of a glass plate. As shown in the figure, R, G, B pixel cells 28 are regularly formed on the surface of the substrate 27. A light shielding film 29 is formed in a mesh shape so as to divide each pixel cell 28, and a spacer aggregate 30 composed of a plurality (for example, 3 to 5) of spacer fine particles is attached to the intersection of the light shielding film 29.

  While a large number of orifices 11 are formed on the discharge head 3 in a straight line with a pitch of P1, the pitch P2 of the spacer aggregate 30 attached on the substrate 27 depends on the type of liquid crystal display device. 11 pitch P1 may be different. In that case, the inclination angle θ of the ejection head 3 is adjusted to match the pitch P2 of the spacer assembly 30.

  FIG. 1 is a schematic configuration diagram of the head cleaning device 7. The head cleaning device 7 includes a cleaning nozzle 31, a cleaning liquid tank 33 that contains a cleaning liquid 32 made of an organic solvent such as isopropyl alcohol, a cleaning liquid pump 34 that supplies the cleaning liquid 32 from the cleaning liquid tank 33 to the cleaning nozzle 31, and a cleaning nozzle. A waste liquid tank 33 for storing the waste liquid collected from 31, a suction means 36 for sucking the cleaning nozzle 31, an internal pressure measuring means 37 comprising a pressure sensor for measuring the internal pressure of the waste liquid tank 33, and cleaning of the discharge head 3 The operations of the separation distance adjusting means 38 for adjusting the separation distance of the nozzles 31, the nozzle moving means 39 for moving the cleaning nozzle 31 in the horizontal direction along the ejection head 3, and the operations of the separation distance adjusting means 38 and the nozzle moving means 39 are as follows. And control means 40 for controlling.

  In the figure, reference numeral 41 denotes a coating liquid tank that contains the coating liquid and is connected to the discharge head 3, and 42 is an internal pressure adjusting means that adjusts the internal pressure of the coating liquid tank 41.

  The cleaning nozzle 31 has a double tube structure of an inner tube 43 and an outer tube 44, a cleaning liquid circulation space 45 is formed between the inner tube 43 and the outer tube 44, and a waste liquid circulation space 46 is formed inside the inner tube 43. Is formed.

  FIG. 2 is an enlarged plan view showing the tip of the cleaning nozzle 31. As shown in the figure, a plurality of grooves 47 are formed at equal intervals along the circumferential direction of the inner tube 43 from the outer periphery of the inner tube 43 toward the inner waste liquid circulation space 46. The groove 47 does not extend radially from the outer periphery of the cleaning nozzle 31 toward the center O, but is inclined by an angle α with respect to a virtual line extending from the starting point A of the outer peripheral portion of the inner tube 43 toward the center O. It extends to do. That is, the grooves 47 are provided so as to be inclined in a certain direction with respect to the middle direction of the inner tube 43. By setting the angle α within a range of, for example, 10 degrees to 30 degrees, the groove 47 extends substantially in the tangential direction with respect to the inner peripheral surface of the inner tube 43.

  In this figure, the thick portions of the inner tube 43 and the outer tube 44 are hatched in order to visually distinguish the thick portions of the inner tube 43 and the outer tube 44 from the cleaning liquid circulation space 45, the waste liquid circulation space 46 and the groove 47. Is attached.

  FIG. 3 is a diagram illustrating a state in which the vicinity of the orifice 11 is cleaned. As shown in the figure, the discharge head 3 is filled with a coating liquid 8 by a coating liquid supply means (configured by a coating liquid tank 41, an internal pressure adjusting means 42, a solution supply pipe 6 and the like). In the coating solution 8, solid fine particles 9 such as spacer fine particles (beads) are mixed and dispersed.

  The particle size of the solid fine particles 9 varies depending on the type of the liquid crystal display device, such as the VA method or the TN method, but usually has a particle size of about 2 μm to 5 μm. The solid fine particles 9 are dispersed at a concentration of, for example, about 0.5 wt% to 20 wt% in a dispersion liquid composed of an organic liquid, water, or a mixed liquid of organic liquid and water. If necessary, a dispersant for maintaining good dispersibility of the solid fine particles 9 or an adhesive for adhering the solid fine particles 9 to the substrate surface may be added.

  In this embodiment, a dispersion liquid in which water and ethylene glycol are mixed and the viscosity is adjusted to about 10 mPa · s so as to enable stable discharge is used, and 1.2% by weight of plastic beads having a diameter of 3.5 μm are used. The dispersed liquid was used as the coating liquid 8.

  As shown in FIG. 1 and FIG. 3, the coating liquid 8 may adhere to the outer surface of the ejection head 3 as droplets due to the filling of the coating liquid 8 into the ejection head 3 described above. 10 etc. are removed by a cleaning device.

  In this cleaning operation, first, the tip of the cleaning nozzle 31 is brought close to the outer surface of the orifice plate 23 in which a large number of orifices 11 are arranged, and the distance between the orifice plate 23 and the cleaning nozzle 31 is adjusted by the separation distance adjusting means 38. To do. The separation distance adjusting means 38 is composed of, for example, a stepping motor and a moving guide, and the cleaning nozzle 31 is used to feed back the pressure value in the waste liquid tank 33 detected by the internal pressure measuring means 37 to an appropriate pressure range in the present invention. The distance between the orifice plate 23 and the cleaning nozzle 31 can be adjusted by driving the mounted movement guide. The distance between the two will be described later.

  Then, the cleaning liquid pump 34 is driven to supply the cleaning liquid 32 to the cleaning liquid circulation space 45 and the suction means 36 is operated to suck the waste liquid circulation space 46. By this suction, the inside of the waste liquid circulation space 46 becomes a negative pressure, and the cleaning liquid 32 is drawn out from the opening of the cleaning liquid circulation space 45 to form a cleaning liquid flow 48 (see FIG. 3) to strongly wash the orifice 11 and its surroundings. Can do. The cleaning liquid after cleaning becomes waste liquid and immediately passes through the waste liquid circulation space 46 and is introduced into the waste liquid tank 35.

  Since a plurality of grooves 47 (see FIG. 2) are formed at the tip of the cleaning nozzle 31, the cleaning liquid flow 48 is mainly concentrated in the grooves 47, and the grooves 47 are in the center direction of the cleaning nozzle 31. Therefore, as shown in FIG. 2, the waste liquid is given swirl energy in the waste liquid circulation space 46 to form a vortex as shown in FIG. The concentration of the cleaning liquid flow 48 and the formation of a vortex flow facilitate the separation of the solid matter adhering to the surface of the orifice plate 23 as well as the liquid droplets 10 adhering to the surface of the orifice plate 23. The solid fine particles 9 contained therein are sucked and removed while rolling.

  Since the cleaning nozzle 31 moves on the orifice plate 23 by the nozzle moving means 39, when the tip opening of the cleaning nozzle 31 reaches a position facing the orifice 11, the coating liquid 8 having increased viscosity by drying in the orifice 11 is formed. The solid fine particles 9 are sucked out and removed, and the purge operation is performed simultaneously.

  FIG. 4 is a characteristic diagram showing the relationship between the suction pressure (negative pressure) and the solid matter adhesion rate when the supply flow rate of isopropyl alcohol (IPA), which is a cleaning liquid, is variously changed. As for the solid matter adhesion rate, the vicinity of the center of the orifice on the head surface is captured by a KEYENCE microscope VH-5910, the image is changed to 1200 dpi, and the white portion (solid matter adhering portion) is binarized and extracted. To obtain the number of pixels with solid matter attached. Then, the ratio of the number of solid matter adhesion pixels to the number of pixels of the image captured as described above is obtained as the solid matter adhesion rate.

  As is apparent from this figure, the solid adhesion rate is high regardless of whether the suction pressure is lower than -9 kPa or higher than -10 kPa, and the solid adhesion rate differs depending on the IPA supply flow rate. On the other hand, if the suction pressure is regulated within the range of −9 kPa to −10 kPa, preferably within the range of −9 kPa to −9.5 kPa, it can be seen that the solid matter adhesion rate is low at any IPA supply flow rate.

  FIG. 5 is a characteristic diagram showing the relationship between the distance D between the surface of the orifice plate and the suction nozzle and the solid matter adhesion rate. As is apparent from this figure, when the separation distance D is 0.06 mm or more, the solid matter adhesion rate is high at any IPA supply flow rate. On the other hand, those in which the separation distance D is regulated in the range of 0.01 mm to 0.05 mm, preferably in the range of 0.02 mm to 0.05 mm, has a low solid matter adhesion rate. Among them, those having an IPA supply flow rate of less than 1.6 ml / min, that is, those in which the IPA supply flow rate is regulated within the range of 0.2 ml / min to 1.0 ml / min have a particularly low solid matter adhesion rate.

  FIG. 6 is a characteristic diagram showing the relationship between the suction distance and the separation distance D between the surface of the orifice plate and the suction nozzle at each IPA supply flow rate, and the optimum suction pressure is plotted against the separation distance D. As is apparent from this figure, there is a correlation between the separation distance D and the suction pressure at each IPA supply flow rate.

  FIG. 7 is a characteristic diagram showing the relationship between the suction pressure and the solid matter adhesion rate when IPA is not supplied (IPA supply flow rate = 0 ml / min black rhombus). As is apparent from this figure, when IPA is not supplied, the solid matter adhesion rate is as high as 2% to 10%, and the effect of using the cleaning agent is remarkable.

  FIG. 8 is an enlarged plan view showing a modification of the tip of the cleaning nozzle 31. A difference from the cleaning nozzle 31 shown in FIG. 2 is that a plurality of grooves 47 are formed from the outer periphery of the outer tube 44 through the inner tube 43 toward the inner waste liquid circulation space 46.

  According to this configuration, outside air is sucked into the waste liquid circulation space 46 from the outside of the outer tube 44, and this outside air flows into the inner tube 43 as an air flow. And the cleaning efficiency of the orifice plate 23 is improved. However, in order to make the inside of the pipe have a negative pressure, the load on the suction means 36 becomes large.

  In the embodiment, isopropyl alcohol is used as the cleaning liquid, but other liquids such as methanol and ethanol can also be used as the cleaning liquid.

  In the embodiment, the case where the coating liquid in which the solid fine particles are mixed and dispersed is described. However, the present invention is not limited to this, and the present invention is also applicable to the case where the coating liquid containing no solid fine particles is discharged.

  In the above-described embodiment, the case of manufacturing a liquid crystal display device has been described. However, the present invention is not limited to this, and can be applied to other technical fields such as the manufacture of electroluminescence.

It is a schematic block diagram of the head cleaning apparatus which concerns on embodiment of this invention. It is an enlarged plan view which shows the front-end | tip part of the washing nozzle in the head cleaning apparatus. It is a figure which shows the state which cleans the vicinity of an orifice with the head cleaning apparatus. It is a characteristic view which shows the relationship between the suction pressure at the time of changing various supply flow rates of IPA, and a solid substance adhesion rate. It is a characteristic view which shows the relationship between the separation distance of the surface of an orifice plate and a suction nozzle, and a solid substance adhesion rate. It is a characteristic view showing the relationship between the distance between the surface of the orifice plate and the suction nozzle and the suction pressure at each IPA supply flow rate. It is a characteristic view which shows the relationship between the suction pressure which described the case where IPA is not supplied, and the solid substance adhesion rate. It is an enlarged plan view which shows the modification of the front-end | tip part of a washing nozzle. 1 is an overall schematic configuration diagram of a droplet discharge device according to an embodiment of the present invention. It is a partial expanded sectional view of the discharge head mounted in the droplet discharge apparatus. It is a top view which shows the relationship between the discharge head which concerns on embodiment of this invention, and the color filter substrate for liquid crystals which adheres a spacer.

Explanation of symbols

  1: Mother substrate, 2: Substrate holder, 3: Discharge head, 4: X direction moving guide, 5: Z direction moving guide, 6: Solution supply pipe, 7: Head cleaning device, 8: Coating liquid, 9: Solid fine particles 10: Adhering droplet, 11: Orifice, 12: Pressurizing chamber, 13: Vibration plate, 14: Piezoelectric element, 15: Signal input terminal, 16: Piezoelectric element fixing plate, 17: Restrictor, 18: Common coating solution Supply pipe, 19: filter, 20: adhesive, 21: restrictor plate, 22: pressurization chamber plate, 23: orifice plate, 24: support plate, 25: housing, 26: filter plate, 27: color filter for liquid crystal Substrate, 28: pixel cell, 29: light shielding film, 30: spacer assembly, 31: cleaning nozzle, 32: cleaning liquid, 33: cleaning liquid tank, 34: cleaning liquid pump, 35: waste liquid tank, 36 Suction means, 37: internal pressure measuring means, 38: distance between distance adjustment means, 39: nozzle moving means, 40: control means, 41: coating liquid tank, 42: internal pressure adjustment means, 43: inner pipe, 44: outer pipe, 45: Cleaning liquid distribution space, 46: Waste liquid distribution space, 47: Groove, 48: Cleaning liquid flow, O: Center of the cleaning nozzle, A: Origin of outer periphery of groove.

Claims (4)

A cleaning nozzle;
Cleaning liquid supply means for supplying a cleaning liquid to the periphery of the front end opening of the cleaning nozzle;
A suction means for sucking the waste liquid circulation space inside the cleaning nozzle,
The front end opening of the cleaning nozzle is opposed to the orifice forming surface of the liquid droplet discharge head in which the orifice for discharging liquid droplets is formed, and the cleaning liquid is supplied around the front end opening of the cleaning nozzle by the cleaning liquid supply means. However, in the cleaning device of the droplet discharge head for sucking the waste liquid circulation space of the cleaning nozzle by the suction means, cleaning the orifice forming surface of the droplet discharge head, and discharging the waste liquid through the waste liquid circulation space,
A cleaning apparatus for a droplet discharge head, wherein a plurality of grooves inclined in a fixed direction with respect to a central direction of the cleaning nozzle are formed in a circumferential direction of a tip portion of the cleaning nozzle . The apparatus for cleaning a droplet discharge head according to claim 1,
The cleaning nozzle has a double tube structure of an inner tube and an outer tube,
A cleaning liquid circulation space is formed between the inner pipe and the outer pipe, and the cleaning liquid supply means is connected to the cleaning liquid circulation space,
The waste liquid circulation space is formed inside the inner pipe,
A cleaning apparatus for a droplet discharge head , wherein the groove is formed at least at the tip of the inner tube . In the cleaning device of the droplet discharge head according to claim 1 or 2,
An apparatus for cleaning a droplet discharge head, wherein the droplet discharge head is a droplet discharge head for discharging a droplet in which solid fine particles are mixed and dispersed . A droplet discharge head in which an orifice for discharging droplets is formed;
A moving means for relatively moving an adherend for landing a droplet discharged from the droplet discharge head and the droplet discharge head;
In a droplet discharge device provided with a cleaning device provided at a standby position of the droplet discharge head,
4. The droplet discharge device according to claim 1, wherein the cleaning device is the cleaning device according to any one of claims 1 to 3.

Images