JP2009297951A - Liquid discharging head cleaning apparatus and liquid discharging apparatus equipped with cleaning apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid discharging head cleaning apparatus using ultrasonic waves which regulates the flow of a cleaning liquid and improves the cleaning effect by preventing re-sticking. <P>SOLUTION: A cleaning liquid is fed into a cleaning tank 8 equipped with an ultrasonic oscillator 9, and an excess cleaning liquid is made to over-flow from a predetermined part 13 on the upper part of the tank wall of the cleaning tank to regulate the flow of the cleaning liquid in one direction. An ultrasonic oscillation is applied to the cleaning liquid, and a face 12a to be cleaned of a liquid discharging head 2 being an object to be cleaned is immersed in the cleaning liquid, to perform an effective cleaning while re-sticking of a contamination component is suppressed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus for cleaning a liquid discharge head and a liquid discharge apparatus including the head cleaning apparatus.

  As a technique for ejecting minute droplets and depositing the minute droplets on a desired region, for example, an inkjet technique in which minute droplets are ejected from a minute nozzle using a piezoelectric material is known. In recent years, it has attracted attention as an industrial application.

  In this inkjet technology, for example, in a manufacturing process of a liquid crystal display device, a process in which a manufacturing cost can be reduced by eliminating a photolithography process, for example, a process of applying red, blue, and green color inks of a color filter for each minute region In addition, it is expected to be applied to a process of applying a liquid containing beads for the purpose of arranging a spacer that regulates the thickness of the liquid crystal layer to be constant. In addition, in a manufacturing process of an organic EL (electroluminescence) device that is attracting attention as a next-generation display technology, a process of forming a polymer-type light emitting layer or the like by a liquid discharge technique has been proposed.

  As described above, liquid ejecting apparatuses for industrial use, for example, inkjet apparatuses, are required to use liquids having various properties according to the field of use. In the following description, the term ink is used as a representative of the liquid, but it is not intended to limit the use of so-called ink.

  Among the various inks, a problem that occurs remarkably in the fast-drying ink type is that a part of the ejected ink adheres to the nozzle plate and dries and solidifies when repeated ejection operations are performed by the inkjet head. . If ink droplets are ejected from the nozzle while the ink is solidified near the nozzle, the ejection direction of the microdroplets will be affected by the solidified ink and the ink landing accuracy will deteriorate, or the worst case As a result, problems such as solidified ink blocking the nozzle opening and the ink itself not being fired occur.

  For this reason, it is required that the nozzle plate of the inkjet head be kept as clean as possible, and the maintenance operation of performing water-repellent treatment on the surface of the nozzle plate or rubbing the ink adhering regularly with a wiper is required. Has been granted.

  Patent Document 1 discloses an apparatus in which an ultrasonic cleaning means is provided in a head portion withdrawal area of a droplet discharge device, and a nozzle plate of an inkjet head is cleaned by ultrasonic cleaning.

  In Patent Document 2, the nozzle plate on which the nozzles of the ink jet head are formed is brought into contact with the open end of the cup, and a cleaning liquid supply port and a discharge port are provided at the bottom of the cup so that the cleaning liquid is supplied to the cavity inside the cup. A technique is disclosed in which ultrasonic cleaning is performed by filling the cleaning liquid and forming a flow of the cleaning liquid and simultaneously applying ultrasonic vibration to the cleaning liquid. As still another embodiment, a technique is shown in which a partition is provided inside the cup in order to form a flow of cleaning liquid along the nozzle plate surface.

In this way, the nozzle plate can be effectively cleaned by performing ultrasonic cleaning on the nozzle plate which has become dirty due to the solidification of the ink.
JP 2003-266719 A (publication date September 24, 2003) JP 2000-117996 A (publication date April 25, 2000)

  The ultrasonic cleaning means described in Patent Document 1 includes a container that can store a cleaning liquid, an ultrasonic generator that can apply ultrasonic waves to the cleaning liquid stored in the container, and the like. In use, an inkjet head as an object to be cleaned is immersed in a container filled with a cleaning liquid such as ethanol, and an ultrasonic wave of, for example, about 28 kHz is applied to the cleaning liquid.

  This is a so-called immersion type ultrasonic cleaning apparatus, and does not create a flow of cleaning liquid in the cleaning tank. In such an immersion type cleaning apparatus, for example, if ultrasonic cleaning is performed in a state where the cleaning liquid is stored, the once removed dirt component may adhere (reattach) to the nozzle plate again, which is desired. There is a problem that the cleaning effect cannot be obtained. Therefore, not only ultrasonic cleaning is performed, but in order to effectively remove dirt components, it is necessary to somehow to prevent reattachment during ultrasonic cleaning, for example, to form a flow of cleaning liquid.

  In Patent Document 2, in order to form a flow of cleaning liquid along the surface of the nozzle plate in the vicinity of the nozzle of the nozzle plate, a cleaning liquid supply port is formed at one end below the cup serving as a cleaning tank, and a discharge port is formed at the other end. A technique for performing ultrasonic cleaning while flowing a cleaning solution is shown. However, in such a structure, the flow of the cleaning liquid is mainly formed near the bottom surface of the lower part in the cleaning tank, and the flow in the upper part of the cleaning tank in which the nozzle plate is arranged cannot be sufficiently formed.

  As another example of Patent Document 2, there is described a structure in which a partition for defining the flow of the cleaning liquid is provided in the cleaning tank. According to this structure, the flow of the cleaning liquid can be formed along the surface of the nozzle plate. However, with this structure, it is expected that the distance from the ultrasonic transducer to the nozzle plate, which is the object to be cleaned, will be long, and the ultrasonic wave will be attenuated during the propagation and the cleaning efficiency will decrease. Furthermore, there is a problem that the entire structure including the partition wall must be vibrated with ultrasonic waves, and the incident energy of the ultrasonic waves to the object to be cleaned is reduced, so that sufficient ultrasonic waves are incident on the cleaning liquid. Has the problem that high power must be applied to the ultrasonic transducer.

Further, as another problem related to Patent Document 2, when an ultrasonic vibrator is vibrated with sufficient strength to allow sufficient ultrasonic waves to enter the cleaning liquid, the inkjet head itself has a considerable strength through the sealing member from the wall of the cleaning tank. There is a problem that ultrasonic waves propagate. In this case, there is a risk that problems such as a loosening of the fixing member of the inkjet head gradually occur.
That is, in the configuration in which the open end of the cup that is a cleaning tank is brought into contact with the inkjet head, the ultrasonic transducer and the inkjet head are connected by a solid object through a short-distance path. There is a problem that vibration is propagated.

  Further, in the cleaning tank structure described in Patent Document 2, since a part of the nozzle plate comes into contact with the seal member provided at the upper end of the cleaning tank, the entire area of the nozzle plate cannot be cleaned, and ink or the like is applied to the seal member. There is a problem of accumulation of soil components.

Alternatively, in the cleaning tank structure described in Patent Document 2, when the cleaning liquid is poured from an empty state in the cleaning tank, the cleaning liquid inflow from the supply port must be larger than the cleaning liquid outflow from the discharge port. In order to keep the cleaning liquid immersed in the nozzle plate while maintaining the pressure in the cleaning tank in a sealed state, the inflow amount and the outflow amount of the cleaning liquid must be matched.
That is, in order to form a state in which the cleaning tank is filled with the cleaning liquid and an empty state, a function for accurately controlling the relationship between the inflow amount and the discharge amount of the cleaning liquid is required. Note that Patent Document 2 also shows a structure for circulating a cleaning liquid. However, the configuration in which the cleaning liquid is circulated in this way can completely match the inflow amount and the discharge amount of the cleaning liquid, but there are cases where the dirt component cannot be removed by a filter or the like due to re-dissolution of the dirt component. In many cases, it is required not to do this.

  Therefore, it is desirable to feed the cleaning liquid with a simple control function without using a method of circulating the cleaning liquid.

  Further, the cleaning liquid is often an organic solvent, and leaving the cleaning tank filled with the cleaning liquid has a problem of fire or diffusion of volatile vapor. For this reason, it is desirable to have a function of quickly discharging the cleaning liquid after cleaning in consideration of the situation at the manufacturing site.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is intended for liquid discharge while having a configuration in which a cleaning tank having an ultrasonic transducer and a liquid discharge head, for example, an inkjet head are not directly connected with a solid material. Provided is a liquid discharge head cleaning device that can form a cleaning liquid flow for effectively cleaning the entire nozzle plate of a head and that can quickly remove the cleaning liquid in the cleaning tank after cleaning. In addition, a liquid discharge apparatus including the liquid discharge head cleaning apparatus as described above is provided.

  In order to solve the above-described problems, in the invention according to the present application, a cleaning tank that stores a cleaning liquid, a cleaning liquid supply unit that supplies the cleaning liquid to the cleaning tank, a cleaning liquid discharge unit that discharges the cleaning liquid from the cleaning tank, and the cleaning A liquid discharge head cleaning device including an ultrasonic vibrator attached to a tank, wherein the cleaning tank is capable of immersing the liquid discharge head, and the cleaning liquid discharge unit is an upper part of a tank wall of the cleaning tank It is characterized in that the cleaning liquid overflows from a specific part of the.

  In this way, by causing the cleaning liquid to overflow from a specific portion at the upper part of the tank wall of the cleaning tank, a “flow substantially parallel to one direction” is formed near the water surface in the vicinity of the specific portion in the cleaning tank. be able to.

  By immersing the liquid discharge head in the “one-way flow in the substantially horizontal direction” of the cleaning liquid formed in the vicinity of the water surface, it is possible to perform effective cleaning without reattachment of dirt components. That is, when the surface to be cleaned of a liquid discharge head such as an inkjet head facing downward is immersed near the water surface of the cleaning tank, the surface of the head to be cleaned flows the cleaning liquid substantially parallel to the surface to be cleaned. It will be placed in. Therefore, the cleaning liquid flows away in one direction while removing the dirt component on the surface to be cleaned of the head, and the effect of suppressing the reattachment of the dirt component is enhanced.

  Furthermore, in the above configuration, if the discharge capacity is higher than the supply capacity of the cleaning liquid, only the excess cleaning liquid can be discharged. Therefore, the cleaning liquid always needs to be cleaned without requiring complicated control on the inflow and discharge of the cleaning liquid. Can be set at a constant liquid level. Therefore, it is possible to easily perform a desired cleaning process by immersing the surface to be cleaned of a liquid discharge head such as an ink jet head in the vicinity of the liquid surface of the cleaning liquid.

  In order to solve the above-mentioned problem, in another invention according to the present application, in the liquid discharge head cleaning device, a part of the upper end of the tank wall of the cleaning tank is configured to be lower than the other part. It is characterized by.

According to the present invention, when the supply of the cleaning liquid into the cleaning tank is continued, the cleaning liquid selectively overflows from the lower part than the other part at the upper end of the tank wall. That is, a specific portion can be formed on the wall portion to be overflowed according to the first aspect, and the flow of the cleaning liquid in the cleaning tank can be defined with a simple configuration.
In order to solve the above-mentioned problem, in another invention according to the present application, in the liquid discharge head cleaning device, a part of the upper end of the tank wall of the cleaning tank has a property of being more lyophilic with respect to the cleaning liquid than the other part. It is characterized by doing so.

  According to this invention, since a part of the upper end portion of the tank wall of the cleaning layer is more lyophilic than the other part, when the supply of the cleaning liquid into the cleaning tank is continued, the lyophilic property is high. The cleaning liquid selectively overflows from the part. More specifically, water repellent treatment may be applied to the upper end portion other than the portion to be overflowed. Further, as in the invention according to claim 2, it is more effective to lower the portion to be overflowed and further subject the other cleaning layer upper end portion to water repellent treatment.

  In order to solve the above-described problem, in another invention according to the present application, in a liquid discharge head cleaning apparatus, a supply port for supplying a cleaning liquid into the cleaning tank is a specific part of an upper part of the tank wall that causes the cleaning liquid to overflow. It is characterized by being arranged in the facing part.

  According to this invention, the flow of the cleaning liquid in the cleaning tank can be more strongly defined in the horizontal direction, and the flow of the cleaning liquid can be formed predominantly in one direction. Further, since the flow of the cleaning liquid can be formed along the surface to be cleaned of the ink jet head, effective cleaning can be performed.

  In order to solve the above-mentioned problem, in another invention according to the present application, in the liquid discharge head cleaning device, a supply port for supplying a cleaning liquid into the cleaning tank is disposed near the bottom surface of the cleaning tank. It is a feature.

  According to the present invention, since the cleaning liquid flowing in from the supply port forms a flow in the height direction, there is an effect of preventing the cleaning liquid from staying in the bottom surface portion of the cleaning tank.

  In order to solve the above-mentioned problem, in another invention according to the present application, in the liquid discharge head cleaning device, the width dimension of the bottom surface of the cleaning tank with respect to the height of the cleaning tank wall surface of the cleaning tank is configured to be twice or more. It is characterized by that.

According to the present invention, since the height of the cleaning tank is designed to be lower than the width of the bottom surface, the flow of the cleaning liquid is mainly in the horizontal direction, and the cleaning liquid at the bottom surface portion is maintained while maintaining a high cleaning effect. It is possible to suppress stagnation.
In order to solve the above-mentioned problem, in another invention according to the present application, in the liquid discharge head cleaning apparatus, a cleaning liquid supply line for supplying a cleaning liquid into the cleaning tank is connected to a waste liquid line via an openable / closable valve. It is characterized by being made.

  According to this invention, after the cleaning process is completed, the cleaning valve in the cleaning tank is supplied from the supply port provided near the bottom of the cleaning tank from the cleaning liquid supply line to the waste liquid line by opening the openable / closable valve. Can be discharged. With this function, the cleaning liquid can be quickly discharged after the cleaning process.

  In order to solve the above-mentioned problem, in another invention according to the present application, in the liquid discharge head cleaning apparatus, an ultrasonic vibrator is attached to the back surface of the bottom surface of the cleaning tank, and the liquid discharge head is cleaned from the surface of the bottom surface. The cleaning operation is performed by setting the distance to the surface to “approximately half of the wavelength in the cleaning liquid” of the ultrasonic wave to be input.

  According to the present invention, when the reflectance of the ultrasonic wave is high at the bottom surface of the cleaning tank and the surface to be cleaned of the liquid discharge head such as an inkjet, it is efficient by strengthening the vibration of the ultrasonic wave in the cleaning liquid. Cleaning is possible. That is, the acoustic impedance of the cleaning tank and the liquid discharge head is made sufficiently larger than the acoustic impedance of the cleaning liquid, and the distance from the bottom surface of the cleaning tank to the surface to be cleaned of the liquid discharge head is input. If it is set to be “an integral multiple of approximately ½ of the wavelength”, the ultrasonic vibration in the cleaning liquid can be strongly retained.

  Moreover, in order to make the flow of the cleaning liquid “mainly in the horizontal direction”, it is desirable that the height is low with respect to the cleaning tank having a certain width. By setting the position of the surface to be cleaned at the above-mentioned “integer multiple of half of the wavelength in the cleaning liquid”, as a result, the height of the cleaning tank itself can be designed low. Therefore, according to the present invention, the flow of the cleaning liquid can be defined in the horizontal direction, and the ultrasonic vibration of the cleaning liquid in the cleaning tank can be effectively enhanced.

  In order to solve the above-described problems, another invention according to the present application is characterized in that the liquid ejection apparatus includes the liquid ejection head cleaning apparatus according to the present invention.

  According to the present invention, in the liquid ejecting apparatus, the liquid ejecting head can be cleaned very easily and efficiently, and whenever necessary, so that the usage efficiency of the liquid ejecting apparatus itself can be improved. it can.

  In the present invention, in the liquid discharge head cleaning device, a cleaning tank for storing the cleaning liquid, a cleaning liquid supply unit for supplying the cleaning liquid to the cleaning tank, a cleaning liquid discharge unit for discharging the cleaning liquid from the cleaning tank, and the cleaning tank A liquid discharge head cleaning device including an ultrasonic vibrator attached to the cleaning tank, wherein the cleaning tank is capable of immersing the liquid discharge head, and the cleaning liquid discharge unit is disposed on an upper part of the tank wall of the cleaning tank. It is characterized by overflowing the cleaning liquid from a specific part.

  As a result, a horizontal flow of the cleaning liquid to which ultrasonic vibration is applied can be formed in the cleaning tank. In this flow, the surface to be cleaned of the liquid discharge head such as an ink jet head is held horizontally downward in the vertical direction, whereby the surface to be cleaned can be efficiently cleaned. That is, since the cleaning liquid flows in the horizontal direction, the reattachment of dirt components to the surface to be cleaned is suppressed, and the cleaning effect can be improved. Furthermore, it is possible to make the predetermined amount of the cleaning liquid with simple control, and the cleaning liquid in the cleaning tank can be quickly discharged, so that it can be operated safely.

Embodiments of the present invention will be described below with reference to the drawings. However, this embodiment is illustrative in all respects and is not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and includes all modifications within the scope and meaning equivalent to the terms of the claims.
[Embodiment 1]
First, an ink jet apparatus equipped with the ink jet head cleaning apparatus according to the first embodiment of the present invention will be described. In this embodiment, the inkjet head cleaning apparatus is described as an example, but the invention of the present application is not particularly limited to the inkjet head cleaning apparatus.

  FIG. 1 is a perspective view showing an overall configuration of an ink jet apparatus according to the present invention. In FIG. 1, reference numeral 7 denotes the entire inkjet apparatus according to the present invention. The stage 1 is for placing a non-processed object 6, the inkjet head 2 is for ejecting ink to the object 6 to be processed, Ink supply unit 4 to be supplied, drive unit 3a for moving inkjet head 2 and ink supply unit 4 in the x-axis direction, drive unit 3b for moving inkjet head 2 and ink supply unit 4 in the y-axis direction, and inkjet head 2 is provided with a maintenance unit 5 for periodically cleaning 2.

  The inkjet head 2, the ink supply unit 4, the drive unit 3a, and the drive unit 3b are connected to a control unit such as a computer (not shown). This control unit controls ink ejection by the ink jet head 2, supply of ink to the ink jet head 2 of the ink supply unit 4, and drive of the drive units 3a and 3b. The drive units 3a and 3b are driven based on a control signal from the control unit, and the inkjet head 2 is moved to a position facing a desired position of the object 6 to be processed.

  Further, a desired amount of ink is ejected from the inkjet head 2 to the object 9 based on a control signal from the control unit. In this way, the ink jet device 7 forms a desired pattern on the workpiece 6.

  The maintenance unit 5 is provided mainly for cleaning dirt on the nozzle surface of the ink jet head 2, and an ink jet head cleaning device equipped with the ultrasonic transducer of the present invention is mounted on the maintenance unit 5.

  2A, 2B, and 2C are views for explaining a cleaning tank structure in the inkjet head cleaning apparatus according to the present invention, in which FIG. 2A is a side sectional view, and FIG. (C) is a perspective view of the cleaning tank.

  In FIG. 2, reference numeral 8 denotes the entire cleaning tank, and an ultrasonic transducer 9 is attached to the bottom of the cleaning tank 8. In this embodiment, the cleaning tank 8 includes an inner tank 8b in which an inkjet head as an object to be cleaned is immersed, and an outer tank 8a for temporarily storing the cleaning liquid discharged from the inner tank 8b. A supply port 10 for supplying a cleaning liquid is provided near the bottom of the side wall of the inner tank 8b, and a pipe 12 is connected by a joint 11. In this embodiment, the opening direction of the supply port 10 is set in a parallel direction (horizontal direction) to the nozzle plate of the inkjet head that is the object to be cleaned. Although it is advantageous for the horizontal direction of the opening to form the horizontal component of the cleaning liquid, it is not an essential requirement.

  A notch 13 for overflowing the cleaning liquid is provided on the upper wall surface of the inner tank 8 b facing the supply port 10, and the outer tank 8 a is integrated as a part of the cleaning tank 8 outside the notch 13. Is formed. A discharge port 14 for discharging the cleaning liquid is provided on the wall surface of the outer tub 8a, and the cleaning liquid is discharged to the outside through the joint 11 and the pipe 12.

  Here, the material of the cleaning tank 8 is preferably a metal such as stainless steel that is resistant to the long-term operation of the ultrasonic vibrator 9. Further, the thinner the bottom surface to which the ultrasonic transducer 9 is attached, the better the transmission of the ultrasonic wave, and it may be set to about 1 to 5 mm from the balance with the strength.

  It is desirable that the height of the wall of the cleaning tank 8 (inner tank 8b) is appropriately set according to the cleaning liquid to be used and the frequency of the ultrasonic wave, and is set to be several mm higher than ½ of the wavelength in the ultrasonic cleaning liquid to be input. Just keep it. For example, when the ultrasonic frequency is 120 kHz and the cleaning liquid is ethanol, the liquid wavelength is 9.5 mm and the wall height is about 5 to 6 mm.

  The cleaning liquid overflows from the inner tank 8b at such a wall surface height. Thus, by causing the cleaning liquid to overflow from a specific portion of the upper portion of the tank wall of the cleaning tank, a substantially horizontal flow in one direction can be formed near the water surface in the vicinity of the specific portion in the cleaning tank. it can.

  If the inkjet head 2 is immersed in the cleaning liquid held in the inner tank 8b in this state by about several millimeters, the distance from the bottom surface of the inner tank 8b of the cleaning tank 8 to the surface to be cleaned of the inkjet head 2 is It can arrange | position so that it may become substantially 1/2 of the wavelength in the washing | cleaning liquid of the ultrasonic wave thrown in, and it becomes possible to perform ultrasonic cleaning in this state.

  The inputted ultrasonic wave propagates from the bottom surface of the cleaning tank 8 and reaches the inkjet head 2 immersed in the cleaning liquid. In such a configuration, the cleaning tank 8 and the surface to be cleaned of the inkjet head 2 serve as a boundary surface in ultrasonic propagation. The acoustic impedance of the cleaning tank 8 and the inkjet head 2 is sufficiently high and the reflectance is high with respect to the acoustic impedance of a liquid such as an organic solvent. In this situation, if the distance between the cleaning tank 8 and the inkjet head 2 is set to approximately ½ of the wavelength in the liquid, a resonance state is established, and the ultrasonic intensity in the cleaning liquid can be strongly maintained.

The ink-jet head 2 is manufactured using various materials, but a metal or a thin organic film is often used for the nozzle plate which is a surface to be cleaned. Acoustic impedance stainless steel 46N · s / ^{m 3} of metal, aluminum was 17N · s / ^{m 3,} for sufficiently larger than the organic cleaning fluid of about 1N · s / ^{m 3,} is understood to strongly reflected at the interface . In addition, although the organic film has a high transmittance because its acoustic impedance is relatively close to that of an organic cleaning solution, it is strongly reflected by the PZT because the base material that bonds the film is made of PZT (lead zirconate titanate), for example. To do. Therefore, it is understood that the ultrasonic wave incident on the inkjet head 2 is also strongly reflected. As a result, by appropriately controlling the arrangement position of the inkjet head 2 as described above, the ultrasonic intensity in the cleaning liquid can be strongly maintained, and the cleaning effect can be improved.

  The type of the ultrasonic transducer 9 to be attached is not particularly specified. A bolt-clamped Langevin type vibrator generally used for an ultrasonic cleaning tank may be used.

  Hereinafter, the cleaning of the inkjet head 2 by supplying the cleaning liquid to the cleaning tank 8 shown in FIG. 2 will be described with reference to FIG.

  First, the cleaning liquid is introduced from the pipe 12 connected to the supply port 10 by the joint 11, and the inner tank 8b is filled with the cleaning liquid. Further, by continuing to introduce the cleaning liquid, the cleaning liquid overflows from the notch 13 to the outer tub 8a and is further discharged from the discharge port 14. In this way, by causing the cleaning liquid to overflow from the notch 13 which is a specific part of the upper part of the tank wall of the cleaning tank, a substantially horizontal direction around the water surface in the region near the notch 13 which is the specific part in the cleaning tank. A flow directed in the direction can be formed.

  In this state, the inkjet head 2 is moved above the cleaning tank 8 so that the nozzle plate 2a faces downward, and then is lowered, so that the inkjet head 2 is immersed in the cleaning liquid in the inner tank 8b of the cleaning tank 8. By operating the ultrasonic vibrator 9, ultrasonic waves are introduced into the cleaning liquid in the cleaning tank 8, and ultrasonic cleaning can be performed on the inkjet head 2. This makes it possible to clean the nozzle plate 2a of the inkjet head 2 that is particularly desired to be cleaned.

  Here, since the notch 13 is provided in the upper wall surface of the inner tub 8b facing the supply port 10, a flow of the cleaning liquid is formed linearly from the supply port 10 toward the notch 13, There is an effect of reducing the components in which the cleaning liquid stays in the horizontal direction.

That is, the surface to be cleaned of a liquid discharge head such as an ink jet head facing downward is placed in a flow of cleaning liquid substantially parallel to the surface to be cleaned. It will flow away in one direction while removing the soil components. Therefore, effective cleaning can be performed while suppressing the reattachment of the dirt components removed by ultrasonic cleaning.
Further, the supply port 10 is formed near the bottom surface of the inner tank 8b. On the other hand, the notch 13 is provided at the upper end of the wall surface of the cleaning tank 8, so that there is an effect of reducing the retention of the cleaning liquid near the bottom surface. . The flow of the cleaning liquid is preferably set in a direction parallel to the nozzle plate 2a that is the surface to be cleaned of the inkjet head 2, that is, in the horizontal direction, from the viewpoint of preventing the reattachment of dirt components. For this reason, it is desirable to set the height of the cleaning tank 8 as low as about 10 mm or less, for example.

  In order to immerse the inkjet head 2, the horizontal size of the cleaning tank 8 needs to be approximately 20 mm or more. If the height of the cleaning tank 8 is defined as 10 mm or less as described above, The value of (bottom surface) / (wall height) is 2 or more, and the main component of the flow of the cleaning liquid can be defined in the horizontal direction.

  If the frequency of the ultrasonic wave input here is 100 kHz or more, the wall surface height of the inner tank 8b can be lowered to about 5 or 6 mm while realizing the resonance state as described above, and the flow of the cleaning liquid can be set in the horizontal direction. Desirable in defining.

  When a flammable liquid is used as the cleaning liquid, a cover 15 is provided so as to cover the ultrasonic vibrator 9 attached to the lower part of the cleaning tank 8 as shown in FIG. It is desirable to provide and electrically connect to the ultrasonic oscillator 16 to isolate the electrical connection from the flammable liquid.

  FIG. 5 shows a cleaning liquid supply line and a waste liquid line to the cleaning tank 8. In FIG. 5, 17 is a cleaning liquid tank that stores the cleaning liquid, and 18 is a waste liquid tank that stores the waste liquid after the inkjet head is cleaned in the cleaning tank 8.

  A pipe is connected from the cleaning liquid tank 17 to the supply port 10 of the cleaning tank 8 through a cleaning liquid pump 19 and an openable / closable electromagnetic valve 21, thereby forming a cleaning liquid supply line. The discharge port 14 of the cleaning tank 8 is connected to a waste liquid tank 18 via an openable / closable electromagnetic valve 22 and a waste liquid pump 20, thereby forming a waste liquid line.

  The cleaning liquid in the cleaning liquid tank 17 can be supplied to the cleaning tank 8 by opening the electromagnetic valve 21 and operating the cleaning liquid pump 19. Further, by opening the electromagnetic valve 22 and operating the waste liquid pump 20, the cleaning liquid overflowing from the notch 13 of the inner tank 8 b to the outer tank 8 a can be discharged to the waste liquid tank 18.

  If the liquid feeding capacity of the waste liquid pump 20 is set higher than the liquid feeding capacity of the cleaning liquid pump 19, the cleaning liquid does not overflow from the cleaning tank 8 to the outside. In addition, since the cleaning liquid is once overflowed from the notch 13 to the outer tank 8a, the inner tank 8b for immersing the inkjet head 2 can continue to satisfy the liquid amount defined by the wall surface height. In other words, the cleaning liquid overflowed from the notch 13 of the inner tank 8b of the cleaning tank 8 to the outer tank 8a is discharged to the waste liquid tank 18 without complicated control of the supply amount and the discharge amount of the cleaning liquid. It is possible to simply fill the cleaning liquid with a desired amount for cleaning, and the cleaning liquid does not overflow.

  Further, in the present invention, the cleaning liquid supply line is branched and connected to the waste liquid line via the electromagnetic valve 23. By providing such a bypass line, the operation of the cleaning liquid pump 19 is stopped and the electromagnetic valve 21 is closed and the electromagnetic valve 22 is opened after the cleaning operation of the inkjet head cleaning device is completed, so that the inner tank 8b is filled. The cleaned cleaning liquid can be quickly discharged to the waste liquid tank. In the illustrated embodiment, the supply port 10 is disposed near the bottom surface of the inner tank 8b, so that the cleaning liquid remaining in the inner tank 8b can be effectively discharged.

This operation may be performed by closing the electromagnetic valve 22 after the cleaning liquid in the outer tub 8a is discharged, or by opening both the electromagnetic valves 22 and 23 and cleaning liquid from the outer tub 8a and the inner tub 8b of the cleaning tub 8. May be discharged at the same time.
The pump for cleaning liquid and the pump for waste liquid should use materials that satisfy the chemical resistance to the cleaning liquid used in the wetted part. For example, if a diaphragm pump made of Teflon (registered trademark) is used, it can be used in various organic solvents. It is also desirable because it can be used.

  The cleaning liquid is not particularly defined. If mixing with the solvent of the ink used in the inkjet head 2 becomes a problem, the solvent of the ink may be selected as the cleaning liquid. Further, for the purpose of increasing the cleaning ability, a material having a low surface energy that can easily penetrate into the gap between the adhered dirt components may be selected. It may be determined in consideration of the type of ink used in the inkjet head 2 and the cleaning ability.

  Further, in the structure of the cleaning tank 8 shown in FIG. 2, one inkjet head 2 is cleaned, but the present invention is not limited thereto.

  FIG. 6 shows a configuration of a cleaning tank 8 for simultaneously cleaning two inkjet heads 2. 6A shows a top view of the cleaning tank 8, and FIG. 6B shows a cross-sectional view taken along the line AA in FIG. 6A.

  In the structure of the cleaning tank 8 shown in FIG. 6A, the cleaning liquid supply line is branched into two in the cleaning tank 8, two supply ports 10 are arranged, and the cleaning liquid is supplied to the inner tank 8b. It is a configuration. And the outer tank 8a is arrange | positioned around the inner tank 8b, and it prevents that the overflowing washing | cleaning liquid overflows outside from the washing tank 8. FIG. A discharge port 14 is provided in the outer tank 8a, and the overflowing cleaning liquid can be quickly discharged from the cleaning tank 8. As described above, the cleaning tank 8 of the present invention does not limit the number of ink jet heads 2, and a plurality of ink jet heads can be simultaneously cleaned using the individual inner tanks 8b.

  In FIG. 6 (a), of the two inner tanks 8b, one notch 13 is arranged at three locations on one side of the wall of the inner tank 8b. The other notch 13 is formed over substantially the entire area of one side of the wall. Thus, by providing a plurality of notch widths or widening the notch width, the flow of the cleaning liquid when overflowing can be formed more evenly in the horizontal direction. According to this configuration, since the cleaning liquid can flow more uniformly in the horizontal direction with respect to the nozzle plate 2a of the inkjet head 2, it is possible to perform cleaning evenly over the entire area of the nozzle plate 2a.

  Moreover, although the supply port with respect to the inner tank 8b of the washing tank 8 is made into one with respect to each washing tank in the thing of illustration, it may be an opening of 2 or more places or a shape wide in a horizontal direction. Further, in the embodiment, as a structure for overflowing the cleaning liquid, a notch structure provided on the upper surface of the wall of the cleaning tank is used, but instead of such a notch structure, for example, provided on the upper surface of the wall surface of the cleaning tank. Opening (hole) may be used.

In addition, in the structure shown to Fig.6 (a), the circumference | surroundings of the inner tank 8b in which the inkjet head 2 is immersed are enclosed as the outer tank 8a. In such a configuration, the bottom surface of the cleaning tank 8 can be made thin in the area of the inner tank 8b and the outer tank 8a. The effect of this configuration will be described below.
The inner tank 8b in which the ink jet head 2 is immersed does not need to be unnecessarily large, and may have a size that allows the ink jet head 2 to be immersed therein. When the size increases, the amount of cleaning liquid supplied to the inner tank 8b increases unnecessarily. For this reason, it is desirable that the inner tank 8b has a minimum size that allows the inkjet head 2 to be immersed therein.

  However, the attachment surface of the ultrasonic transducer 9 with the cleaning tank 8 is not necessarily smaller than the inner tank 8b. In the case of the bolted Langevin type vibrator, the mounting surface with the cleaning tank 8 is a circle having a diameter of about 40 mm or more. When the inner tub 8b may be smaller than that, the outer tub 8a is arranged around the inner tub 8b, so that the bottom surface of the entire surface to which the ultrasonic transducer 9 is attached is removed except for the region of the wall of the cleaning tub. Can be thin. Therefore, it becomes the structure which can propagate an ultrasonic wave efficiently.

  FIG. 7 shows the attachment position of the ultrasonic transducer 9 in the cleaning tank structure shown in FIG. FIG. 7 shows a case where the attachment surface area of the ultrasonic transducer 9 is larger than the area of the inner tank 8b. In such a case, the outer tub 8a is provided around the inner tub 8b, and the bottom surface of the outer tub 8a is designed to be thin so that the ultrasonic waves generated by the ultrasonic transducer 9 can be efficiently generated inside the inner tub 8b. It can be propagated to the cleaning liquid.

[Embodiment 2]
In the second embodiment, in the structure of the cleaning tank 8, the method of overflowing from the specific part of the cleaning tank is different from that of the first embodiment, and other than that is the same as in the first embodiment. Therefore, description of overlapping structures, configurations, and means is omitted.
As shown in FIGS. 8A and 8B, the configuration of the cleaning tank 8 shown in the second embodiment includes a liquid repellent treatment surface 24 in which the upper end of the cleaning tank 8 is partially liquid repellent, The other unprocessed surface 25 is provided separately. That is, the untreated surface 25 has a higher lyophilic property with respect to the cleaning liquid than the liquid repellent treated surface 24.

  When the cleaning liquid supplied from the supply port 10 overflows, the liquid repellent treatment surface 24 has higher liquid repellency than the untreated surface 25, so that the cleaning liquid is blocked on the liquid repellent treatment surface 24. Therefore, the cleaning liquid overflows from the untreated surface 25 as the specific portion, and the cleaning liquid flows to the outer tank 8a.

  That is, in this embodiment, not a notch but a surface having a contrast between lyophilic and liquid repellent is provided to realize overflow from the specific portion.

  As described above, the cleaning tank 8 is preferably made of metal such as stainless steel. Since metals are generally excellent in lyophilicity, liquid repellent treatment may be applied to the upper end portion other than the specific portion to be overflowed. Although the liquid repellent treatment method is not particularly specified, the water repellent treatment liquid may be applied to a necessary portion. As the water repellent treatment liquid, an amorphous fluororesin-based one or a fluorine-based silane coupling agent is known. For example, Cytop (registered trademark) manufactured by Asahi Glass Co., Ltd., OPTOOL (registered trademark) manufactured by Daikin, etc. A commercially available product may be used.

  In addition, since the cleaning liquid is discharged before the upper end of the wall corresponding to the outer tub 8a particularly overflows, the liquid repellent treatment is not particularly required.

  Further, in combination with the first embodiment, a notch 13 for overflowing the cleaning tank 8 may be provided, and a liquid repellent treatment may be applied to the upper end portion other than the notch 13.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and technical means disclosed in different embodiments are appropriately combined. Embodiments obtained in this manner are also included in the technical scope of the present invention.

  According to the present invention, it can be used as an inkjet head cleaning device for effectively cleaning nozzle plate contamination caused by the operation of the inkjet head device using ultrasonic waves. And since the flow of the cleaning liquid is regulated, it is possible to prevent the re-adhesion of dirt components and to fully demonstrate the cleaning effect, and after the ultrasonic cleaning operation is completed, the cleaning liquid in the cleaning tank can be discharged quickly, so that the device manufacturing It can be safely operated even in such facilities.

It is a figure for demonstrating the structural example of the inkjet apparatus incorporating the inkjet head cleaning apparatus which concerns on this invention. It is a figure for demonstrating the washing tank structure shown in Embodiment 1 in the inkjet head cleaning apparatus which concerns on this invention. FIG. 3 is a diagram for explaining an operation of supplying the cleaning liquid and cleaning the inkjet head in the cleaning tank shown in FIG. 2. It is a figure for demonstrating the structure which covered the ultrasonic transducer | vibrator attached to the lower surface of the washing tank shown in FIG. 2 with the cover. It is a figure for demonstrating the washing | cleaning liquid supply line and waste liquid line of the inkjet head cleaning apparatus which concerns on this invention. It is a figure for demonstrating the structure of the washing tank which immerses and wash | cleans several inkjet heads separately in several internal tanks in the inkjet head cleaning apparatus which concerns on this invention. It is a figure for demonstrating the structure in case the inner tank size of the washing tank in the inkjet head cleaning apparatus which concerns on this invention is larger than the attachment surface of an ultrasonic transducer | vibrator, The structure which provided the outer tank around the inner tank Show. It is a figure for demonstrating the washing tank structure shown in Embodiment 2 in the inkjet head cleaning apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stage 2 Inkjet head 3a Drive part moved to x-axis direction 3b Drive part moved to y-axis direction 4 Ink supply unit 5 Maintenance unit 6 Non-processed object 7 Inkjet apparatus 8 Cleaning tank 8a Outer tank 8b Inner tank 9 Ultrasonic vibration Child 10 Supply port 11 Joint 12 Piping 13 Notch 14 Discharge port 15 Cover 16 Ultrasonic oscillator 17 Cleaning liquid tank 18 Waste liquid tank 19 Cleaning liquid pump 20 Waste liquid pump 21 Electromagnetic valve 22 Electromagnetic valve 23 Electromagnetic valve 24 Liquid repellent surface 25 Not yet used Processing surface

Claims (9)

A liquid comprising: a cleaning tank that contains a cleaning liquid; a cleaning liquid supply unit that supplies the cleaning liquid to the cleaning tank; a cleaning liquid discharge unit that discharges the cleaning liquid from the cleaning tank; and an ultrasonic transducer attached to the cleaning tank. A discharge head cleaning device,
2. The liquid discharge head cleaning apparatus according to claim 1, wherein the cleaning tank is capable of immersing the liquid discharge head, and the cleaning liquid discharger causes the cleaning liquid to overflow from a specific portion at an upper portion of the tank wall of the cleaning tank.   The liquid cleaning head cleaning apparatus according to claim 1, wherein a part of the upper end of the tank wall of the cleaning tank has a lower structure than the other part.   3. The liquid discharge head cleaning apparatus according to claim 1, wherein a part of the upper end portion of the tank wall of the cleaning tank is more lyophilic with respect to the cleaning liquid than the other part.   The liquid discharge according to any one of claims 1 to 3, wherein a supply port for supplying a cleaning liquid into the cleaning tank is arranged at a facing portion of a specific portion of an upper part of the tank wall where the cleaning liquid overflows. Head cleaning device.   5. The liquid discharge head cleaning apparatus according to claim 1, wherein a supply port for supplying a cleaning liquid into the cleaning tank is disposed near a bottom surface of the cleaning tank.   6. The liquid discharge head cleaning apparatus according to claim 1, wherein the width of the bottom surface of the cleaning tank with respect to the height of the cleaning tank wall surface of the cleaning tank is twice or more.   7. The liquid discharge head cleaning according to claim 5, wherein a cleaning liquid supply line for supplying a cleaning liquid into the cleaning tank is connected to a waste liquid line via an openable / closable valve. apparatus.   The ultrasonic transducer was attached to the back surface of the bottom surface of the cleaning tank, and the distance from the surface of the bottom surface to the surface to be cleaned of the liquid discharge head was set to approximately ½ of the wavelength in the ultrasonic cleaning liquid to be input. The liquid discharge head cleaning apparatus according to claim 1, wherein:   A liquid ejection apparatus comprising the liquid ejection head cleaning apparatus according to claim 1.

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