TWI625248B - Inkjet coating liquid controlling device - Google Patents

Abstract

The inkjet coating liquid control device 1A of the present invention includes a supply flow path 5A and a return flow path 7A of the coating liquid to the inkjet head IJ, and a control groove 3A for storing the coating liquids connected to the flow paths. The circulation path of the coating liquid for the inkjet head IJ is included, and includes a negative pressure generating member 20A that generates a negative pressure corresponding to the meniscus pressure at the nozzle NZ of the inkjet head IJ, and the equivalent The sum of the pressures of the heads of the grooves 3A is controlled, and this negative pressure is applied to the control grooves 3A.

Description

Inkjet coating liquid control device

The present invention relates to an inkjet coating liquid control device, and more particularly to an inkjet coating liquid control device which is connected to a flow path leading to an inkjet head and is connected to the flow path and stored. The control tank of the coating liquid constitutes a circulation path or a non-circulation path of the coating liquid for the inkjet head.

As is well known, an inkjet coating device typified by an ink jet printer is provided with an inkjet coating liquid control device that supplies a coating liquid to an inkjet head and uses the inkjet coating device. To control its supply pattern. In the inkjet coating liquid control device, a flow path that communicates with the inkjet head and a groove that supplies the coating liquid to the inkjet head through the flow path are mainly used as the main components, and A circulation path or a non-circulating path of the coating liquid of the ink head.

As an example, Patent Document 1 discloses an inkjet coating liquid control device that provides a single ink tank (1) when a plurality of inkjet heads (4) are supplied as a coating liquid as a liquid material. And the recovery tank (8), the two tanks (1) and the tanks (8) are connected by a common liquid supply line (2), and the plurality of independent liquid supply lines (3) are connected from the common liquid supply line ( 2) branch and connect the separate liquid supply lines (3) For each inkjet head (4). This device constitutes a non-circulating path for the inkjet head (4).

In the acyclic path in the apparatus, a coating liquid that is sufficiently deaerated is supplied to the inkjet head as a main problem. Therefore, while the inkjet head (4) is supplied to the coating liquid while the coating tank (8) is supplied from the ink tank (1), the nozzles of the inkjet heads (4) are not invaded. Gas or air bubbles for sufficient degassing.

Prior art literature

Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2005-193618

However, in the configuration of the inkjet coating liquid control device disclosed in Patent Document 1, since the inside of the inkjet head can be sufficiently deaerated, the meniscus of the nozzle of the inkjet head is used. There is no problem with the fine-tuning of pressure. Therefore, it is impossible to prevent the ink from dripping from the nozzle of the ink jet head and the ejection is not optimal.

On the other hand, the inventors of the present invention attempted to use the inkjet coating liquid control device shown below by finely adjusting the pressure of the meniscus of the nozzle for inkjet.

Fig. 5 shows an example of the apparatus, and constitutes a circulation path of the coating liquid for the ink jet head IJ. As shown in the figure, in the inkjet coating liquid control device 1X, the control tank includes a supply tank 2X and a return tank 3X, and the two tanks 2X and 3X communicate with each other via the communication passage 4X. The supply tank 2X supplies the coating liquid to the inkjet head IJ via the supply flow path 5X. Further, the return tank 3X returns the coating liquid from the inkjet head IJ via the return flow path 6X. Further, the supply tank 2X communicates with the replenishing tank 8X via the replenishing passage 7X.

Next, the operation of the inkjet coating liquid control device 1X will be briefly described. The replenishing tank 8X replenishes the supply tank 2X with the replenishing flow path 7X of the supply pump 9X and the supply valve 10X, and the liquid level of the coating liquid in the supply tank 2X is always at the upper limit position 2L1 and the lower limit position 2L2. The way between the liquid level control. In the state where the liquid level control is performed, by opening the atmosphere opening valve 11X and opening the head supply valve 12X and the head circulation valve 13X, the coating liquid in the supply tank 2X passes through the ink jet head IJ, and by The lift naturally falls to the return slot 3X. The natural falling speed of the coating liquid in this case is determined by the position of the return groove 3X in the vertical direction.

Further, in Fig. 7, as shown in a partial longitudinal enlarged view with the symbol A attached thereto, the shape of the meniscus MK at the nozzle NZ is determined by the magnitude of the back pressure when the coating liquid passes through the ink jet head IJ. In this case, if it is the shape of the meniscus MK shown in FIG. 7, the coating liquid can be appropriately dripped from the nozzle NZ. Further, in order to set the shape of the meniscus MK to an optimum shape, the return groove 3X is moved up and down to adjust the position. Further, by the position adjustment, the discharge amount or the discharge frequency when the coating liquid is ejected from the ink jet head IJ is also optimal. Here, the size of the symbol P2 attached in FIG. 5 corresponds to the meniscus pressure, and the size of the symbol P1 is attached to correspond to the pressure corresponding to the head.

When the liquid level of the coating liquid in the return tank 3X rises, the liquid level sensor (not shown) detects that the liquid surface has reached the upper limit position 3L1, and is provided in the communication flow path 4X. Circulating pump 14X drives and circulates the valve 15X is opened, and the coating liquid is returned from the return tank 3X to the supply tank 2X. When the liquid level of the coating liquid in the return tank 3X reaches the lower limit position 3L2, the circulation valve 15X is closed, the driving of the circulation pump 14X is stopped, and the coating liquid in the return tank 3X is increased. Therefore, by repeating the driving and stopping of the circulation pump 14X, the liquid level control is performed such that the liquid level of the coating liquid in the return tank 3X is always between the upper limit position 3L1 and the lower limit position 3L2.

Fig. 6 is a view showing another example of the inkjet coating liquid control device which the inventors tried to use, and which constitutes a non-circulating path of the coating liquid for the ink jet head. As shown in the figure, the inkjet coating liquid control device 1Y includes a single control tank 2Y that supplies a coating liquid to the inkjet head IJ via the supply flow path 3Y. The supply flow path 3Y branches into two branch passages 4Y so as to pass to both end portions of the ink jet head IJ in the longitudinal direction. Further, the control tank 2Y communicates with the replenishing tank 6Y via the replenishing flow path 5Y.

Next, the operation of the inkjet coating liquid control device 1Y will be briefly described. The replenishing tank 6Y replenishes the coating tank 2Y via the replenishing passage 5Y of the supply pump 7Y and the supply valve 8Y, and controls the liquid level of the coating liquid in the tank 2Y to always be at the upper limit position 2L1 and the lower limit position 2L2. The way between the liquid level control. In the state where the liquid level control is performed, the two head supply valves 9Y are opened, and the head pressurizing valve 10Y is opened to pressurize the inside of the control tank 2Y, thereby filling the coating liquid in the control tank 2Y to The inside of the ink jet head IJ.

Then, the head pressurizing valve 10Y is closed, and the atmosphere opening valve 11Y is opened, whereby the coating liquid is ejected from the nozzle NZ by the action of the piezoelectric element in the ink jet head IJ, so that the ink can be ejected from the control groove 2Y. The head IJ supplies a coating liquid. In this state, The liquid level of the coating liquid in the control groove 2Y is lower than the front end portion of the nozzle NZ on the lower surface of the ink jet head IJ, and thus a meniscus corresponding to the size indicated by the symbol P2 in Fig. 6 is generated. The surface pressure is determined, and the shape of the meniscus MK at the nozzle NZ shown in Fig. 7 is determined.

As described above, there are still problems to be solved according to the two types of inkjet coating liquid control device 1X and inkjet coating liquid control device 1Y which the present inventors attempted to use.

In the apparatus 1X and the apparatus 1Y, the control tank 3X and the control tank 2Y are both disposed below the inkjet head IJ, the object to be coated 16X, and the object to be coated 12Y, so that the ink is ejected. When the head IJ or the object to be coated 16X and the object to be coated 12Y are moved in the horizontal direction, there is a possibility that interference occurs between the control groove 3X and the control groove 2Y. Therefore, there is a problem in that the layout of each unit of the device 1X and the device 1Y is restricted, and the degree of freedom in design is reduced.

Further, when the shape of the meniscus is variably controlled to have an optimum shape, it is necessary to finely adjust the position of the control groove in the vertical direction, and it is necessary to provide a position adjustment mechanism to the control groove. Therefore, it also causes a significant problem that it is difficult to easily control the shape of the meniscus.

In view of the above, it is a technical object of the present invention to provide an inkjet coating liquid control device which can increase the degree of freedom of design and can easily change the shape of a meniscus easily.

According to a first aspect of the invention, the inkjet coating liquid control device is provided with a supply flow path and a return flow path of a coating liquid to an inkjet head, and A circulation path for the coating liquid for the inkjet head is formed by connecting the flow channels and the control tank for storing the coating liquid, and the inkjet coating liquid control device is characterized in that the control tank includes: a supply channel for supplying a coating liquid to the inkjet head, and a return groove that communicates with the supply groove and returns to the coating liquid from the inkjet head via the return flow path, and the inkjet coating liquid control device And a negative pressure generating member that generates a negative pressure corresponding to a sum of a meniscus pressure at a nozzle of the inkjet head and a pressure corresponding to a head of the return tank, the negative pressure generating member It is configured to cause a negative pressure to act on the return groove.

According to this configuration, since the control tank has the supply tank and the return tank, the coating liquid that has reached the inkjet head from the supply tank through the supply flow path passes through the inkjet head, and then returns to the return tank through the return flow path. Then, the coating liquid returned to the return tank is sent to the supply tank, thereby constituting a circulation path for the coating liquid of the ink jet head. In this case, the shape of the meniscus at the nozzle is determined by the magnitude of the back pressure when the coating liquid passes through the inkjet head. Therefore, the first invention includes a negative pressure generating member that generates a negative pressure corresponding to the sum of the meniscus pressure and the pressure corresponding to the head of the return groove (added pressure), and The resulting negative pressure acts on the return tank. Thereby, the magnitude of the back pressure when the coating liquid passes through the ink jet head can be made optimal, and the shape of the meniscus can also be an optimum shape. Further, in order to variably control the shape of the meniscus, it is only necessary to variably control the magnitude of the negative pressure generated by the negative pressure generating member, so that the shape of the meniscus can be easily fine-tuned. Further, in the circulation path of the above configuration, the air bubbles inside the inkjet head are returned to the returning groove via the return flow path, so that the air bubbles are not ejected from the nozzle. Moreover, if it is the above composition, the supply is The position of the groove or the return groove in the up and down direction is not restricted, and thus the degree of freedom for designing the set positions is increased.

In this configuration, it is preferable that the negative pressure generating member has a structure that suppresses pulsation generated in the negative pressure.

According to this, since the pulsation of the negative pressure of the coating liquid acting on the return tank can be eliminated, pulsation can be prevented from occurring in the coating liquid passing through the inkjet head. Thereby, it is also possible to prevent the occurrence of pulsation in the shape of the meniscus, so that a meniscus having an optimum shape which is always stable can be produced.

In this case, as the negative pressure generating member that can suppress the pulsation generated in the negative pressure, a negative pressure generating device having a regulator and an ejector type can be cited. Further, even if the negative pressure generating member other than the negative pressure generating member having a structure capable of suppressing the pulsation generated in the negative pressure is used, the same advantages as those described above can be obtained.

According to a second aspect of the present invention, in an inkjet coating liquid control device, a supply flow path and a return flow path of a coating liquid to an inkjet head are connected to the flow paths and stored. a control tank for the coating liquid to constitute a circulation path of the coating liquid for the inkjet head, the inkjet coating liquid control device characterized in that the control tank is a single tank, and the single tank doubles as a supply a supply channel for supplying a coating liquid to the inkjet head, and a returning groove for returning the coating liquid from the inkjet head via the return flow path, and the inkjet coating liquid control device includes a negative pressure for generating a negative pressure Generating a component, the negative pressure corresponding to a sum of a meniscus pressure at a nozzle of the inkjet head and a pressure corresponding to a head of the control tank, the negative pressure generating member being disposed in the slave The ink jet head leads to the middle of the return flow path of the control groove.

According to this configuration, since the control groove is a single groove that serves as both the supply groove and the return groove, the coating liquid that has reached the inkjet head from the single control groove via the supply flow path passes through the inkjet head and passes through the return flow. Return to the single slot. Thereby, a circulation path of the coating liquid for the inkjet head is formed. In this case, the shape of the meniscus at the nozzle is determined by the magnitude of the back pressure when the coating liquid passes through the inkjet head. Therefore, the second invention includes a negative pressure generating member that generates a negative pressure corresponding to the sum of the meniscus pressure and the pressure corresponding to the head of the control tank (added pressure), and The generated negative pressure acts on the middle of the return flow path. Thereby, the magnitude of the back pressure when the coating liquid passes through the ink jet head can be made optimal, and the shape of the meniscus can also be an optimum shape. Further, in order to variably control the shape of the meniscus, it is only necessary to variably control the magnitude of the negative pressure generated by the negative pressure generating member, so that the shape of the meniscus can be easily fine-tuned. Further, in the circulation path of the above configuration, the air bubbles in the ink jet head are returned to the control groove via the return flow path, so that the air bubbles are not ejected from the nozzle. Further, according to the above configuration, since the position of the supply groove or the return groove in the vertical direction is not restricted, the degree of freedom for designing the installation positions is increased.

In this configuration, it is also preferable that the negative pressure generating member has a structure for suppressing pulsation generated in the negative pressure.

According to this, since the pulsation of the negative pressure acting on the coating liquid flowing through the return flow path can be eliminated, as a result of the above, a meniscus having an optimum shape which is always stable can be produced.

The negative pressure generating member that can suppress the pulsation generated in the negative pressure in this case is an impeller type negative pressure pump, and is well-known as long as it has a structure capable of suppressing pulsation generated in the negative pressure. Negative pressure generating parts can be used in other forms.

According to a third aspect of the present invention, in an inkjet coating liquid control device, a supply flow path of a coating liquid to an inkjet head is coupled to the supply flow path and stored and coated. a control tank for the liquid to constitute a non-circulating path of the coating liquid for the inkjet head, the inkjet coating liquid control device being characterized in that the control tank is a single tank, and the inkjet coating liquid The control device includes a negative pressure generating member that generates a negative pressure corresponding to a sum of a meniscus pressure at a nozzle of the inkjet head and a pressure corresponding to a head of the control tank, the negative pressure The generating member is configured to cause a negative pressure to act on the control groove, and the inkjet coating liquid control device is configured to selectively switch an operation of causing a negative pressure by the negative pressure generating member and cancel the negative pressure The action of the action.

According to this configuration, the control groove is a single groove, and the control groove is connected only to the supply flow path to the inkjet head, so that the flow of the coating liquid becomes the supply flow path from the control groove toward the inkjet head. one direction. Thereby, a non-circulating path of the coating liquid for the inkjet head is formed. In this case, the shape of the meniscus at the nozzle is determined by the magnitude of the back pressure when the coating liquid passes through the inkjet head. Therefore, the third invention includes a negative pressure generating member that generates a negative pressure corresponding to the sum of the meniscus pressure and the pressure corresponding to the head of the control tank (added pressure), and The generated negative pressure acts on the control tank. Thereby, when the coating liquid can pass through the inkjet head The size of the back pressure is the optimum size, and the shape of the meniscus can also be an optimum shape. Further, in order to variably control the shape of the meniscus, the magnitude of the negative pressure generated by the negative pressure generating member can be variably controlled, so that the shape of the meniscus can be easily fine-tuned. Further, when the negative pressure is caused by the negative pressure generating member as described above, the meniscus is generated as described above, and when the state is switched from the state to the state in which the negative pressure is released, The nozzle of the inkjet head forcibly ejects the coating liquid to discharge the air bubbles inside the inkjet head. Therefore, air bubbles do not remain inside the ink jet head. Further, according to the above configuration, the position of the control groove in the vertical direction is not restricted, and thus the degree of freedom for designing the installation position is increased.

In this configuration, it is also preferable that the negative pressure generating member has a structure for suppressing pulsation generated in the negative pressure.

According to this, it is possible to eliminate the pulsation of the negative pressure of the coating liquid acting on the control tank, and as a result, it is possible to generate a meniscus having an optimum shape which is always stable as in the case described above.

In this case, the negative pressure generating member having a structure that can suppress the pulsation generated in the negative pressure includes a ejector-type negative pressure generating device having a regulator, and has a structure capable of suppressing pulsation generated in the negative pressure. Known negative pressure generating components can also be used in other forms.

According to a fourth aspect of the present invention, in an inkjet coating liquid control device, a supply flow path of a coating liquid to an inkjet head is connected to the supply flow path, and a coating liquid is stored. a groove for constituting a non-circulating path of a coating liquid for an inkjet head, the inkjet coating liquid control device being characterized in that the control groove is a single a groove, and the inkjet coating liquid control device includes a negative pressure generating member that generates a negative pressure corresponding to a meniscus pressure at a nozzle of the inkjet head, and is equivalent to the control The sum of the pressures of the lifts of the grooves, wherein the negative pressure generating member is configured to cause a negative pressure to act in the middle of the supply flow path from the control groove to the ink jet head, and the ink jet coating liquid control device is configured The operation of the negative pressure generating member to selectively actuate the negative pressure and the action of releasing the negative pressure are selectively switched.

According to this configuration, the control groove is a single groove, and the control flow path is only connected to the supply flow path to the inkjet head, so that the flow of the coating liquid becomes the supply flow path from the control groove toward the inkjet head. one direction. Thereby, a non-circulating path of the coating liquid for the inkjet head is formed. In this case, the shape of the meniscus at the nozzle is determined by the magnitude of the back pressure when the coating liquid passes through the inkjet head. Therefore, the third invention includes a negative pressure generating member that generates a negative pressure corresponding to the sum of the meniscus pressure and the pressure corresponding to the head of the control tank (added pressure), and This generated negative pressure acts on the middle of the supply flow path. Thereby, the magnitude of the back pressure when the coating liquid passes through the ink jet head can be made optimal, and the shape of the meniscus can also be an optimum shape. Further, in order to variably control the shape of the meniscus, it is only necessary to variably control the magnitude of the negative pressure generated by the negative pressure generating member, so that the shape of the meniscus can be easily fine-tuned. In the state in which the negative pressure is exerted by the negative pressure generating member as described above, the meniscus is generated as described above, and when the state is switched from the state to the state in which the negative pressure is released, The nozzle of the inkjet head forcibly ejects the coating liquid, thereby discharging the air bubbles inside the inkjet head. Therefore, air bubbles do not remain inside the ink jet head. Further, in the above configuration, the vertical direction of the control groove The position is not constrained, and thus the degree of freedom for designing the set position is increased.

In this configuration, it is also preferable that the negative pressure generating member has a structure for suppressing pulsation generated in the negative pressure.

According to this, since the pulsation of the negative pressure acting on the coating liquid flowing through the supply flow path can be eliminated, as a result of the above, a meniscus having a stable optimum shape can be produced.

The negative pressure generating member which is a structure that can suppress the pulsation generated in the negative pressure in this case is an impeller type negative pressure pump, and is a well-known negative pressure generating structure having a structure capable of suppressing pulsation generated in the negative pressure. For parts, it is fine to use other forms.

In the above configuration, it is preferable that the control groove is disposed above the ink jet head.

According to this, even in the case where the ink jet head or the object to be coated is moved in the lateral direction, regardless of the directivity of the lateral movement, it is possible to avoid such a situation in which interference with the control groove occurs.

As described above, according to the first invention, the second invention, the third invention, and the fourth invention, it is possible to realize inkjet coating which can increase the degree of freedom of design and can easily change the shape of the meniscus. Liquid control device.

1A, 1B, 1C, 1D, 1X, 1Y‧‧‧ inkjet coating liquid control device

2A‧‧‧Control slot (supply slot)

2Aa, 2Ba, 2Ca, 2Da, 3Aa‧‧‧ upper space

2B, 2C, 2D, 2Y‧‧‧ control slots

2L1, 3L1‧‧‧ upper limit position

2L2, 3L2‧‧‧ lower limit position

2X‧‧‧ supply slot

3A‧‧‧Control slot (return slot)

3B, 3C, 3D, 3Y, 5A, 5X‧‧‧ supply flow paths

3Ca‧‧‧Base supply flow path

3Cb‧‧‧ branch supply flow path

3Da, 5Ba‧‧‧ upstream side part

3Db, 5Bb‧‧‧ downstream side section

3Dc‧‧‧backstream supply flow path

3Dd‧‧‧ branch downstream supply flow path

3X‧‧‧ return slot

4B, 4C, 4D, 6A, 9Y, 12X‧‧‧ head supply valves

4X, 9A‧‧‧ connected flow path

4Y‧‧‧ branch access

5B, 6X, 7A‧‧‧ return flow path

5C, 5D, 6Y, 7B, 8X, 12A‧‧ ‧ supplementary slots

5Y, 6C, 6D, 7X, 8B, 13A‧‧‧ supplementary flow paths

6B, 8A, 13X‧‧‧ head circulation valve

7C, 7D, 8Y, 10B, 10X, 14A‧‧‧ supply valves

7Y, 8C, 8D, 9B, 9X, 15A‧‧‧ supply pumps

9C, 11X, 11Y, 16A‧‧‧ atmosphere open valve

9D, 11B‧‧‧1st atmospheric open valve

10A, 15X‧‧‧ cycle valve

10C, 10D, 12B, 17A, 18D, 22B‧‧‧ atmospheric circulation flow path

10Y, 18C, 25D‧‧‧ head pressure valve

11A, 14X‧‧ Circulating pump

11C, 18A‧‧‧ Negative pressure valve

11D, 13B‧‧‧ negative pressure pump unit

12C, 19A‧‧‧ Negative pressure circulation flow path

12D, 14B‧‧‧ unit housing

12Y, 16X, 19C, 24A, 26D, 28B‧‧‧ coated objects

13C, 20A‧‧‧ Negative pressure generating parts (negative pressure generating device)

13D, 15B‧‧‧ motor

14C, 20D, 21A, 24B‧‧‧ control flow path

14D, 16B‧‧‧ axis

15C, 22A‧‧‧Auxiliary negative pressure valve

15D, 17B‧‧‧ impeller

16C, 22D, 23A, 26B‧‧‧ pressure gauge

16D, 18B‧‧‧ Negative pressure generating parts (negative pressure pump)

16S, 22S, 23S, 26S, 27S‧‧‧ electrical signals

17C, 24D‧‧‧ pressurized flow path

17D, 19B‧‧‧ internal flow path

19D, 23B‧‧‧2nd atmospheric open valve

20B‧‧‧ bypass flow path

21B‧‧‧ Bypass valve

21D, 25B‧‧‧ pressure valve

23D, 27B‧‧‧ Negative Pressure Pump Control Department

P1‧‧‧ is equivalent to the pressure of the head

P2‧‧‧ meniscus pressure

IJ‧‧‧ inkjet head

NZ‧‧‧ nozzle

MK‧‧‧ meniscus

Fig. 1 is a view showing an inkjet coating liquid control device according to a first embodiment of the present invention. A schematic diagram.

FIG. 2 is a schematic configuration diagram of an inkjet coating liquid control device according to a second embodiment of the present invention.

3 is a schematic configuration diagram of an inkjet coating liquid control device according to a third embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of an inkjet coating liquid control device according to a fourth embodiment of the present invention.

Fig. 5 is a schematic configuration diagram showing an inkjet coating liquid control device according to a basic concept of the present invention.

Fig. 6 is a schematic configuration diagram showing an inkjet coating liquid control device according to a basic concept of the present invention.

FIG. 7 is a schematic view showing a shape of a meniscus generated by a nozzle of the inkjet coating liquid control device of the present invention.

Hereinafter, an inkjet coating liquid control device according to an embodiment of the present invention will be described with reference to the drawings.

Fig. 1 shows a schematic configuration of an inkjet coating liquid control device 1A according to the first embodiment of the present invention. As shown in the figure, in the inkjet coating liquid control device 1A, the control tank includes two slots of the supply tank 2A and the return tank 3A, and the supply tank 2A and the inside of the inkjet head IJ are connected via the supply flow path 5A, and A head supply valve 6A, which is an opening and closing valve, is provided in the supply flow path 5A. Further, the return groove 3A is connected to the inside of the ink jet head IJ via the return flow path 7A, and the head of the return flow path 7A is provided as an opening and closing valve. Circulation valve 8A. Further, the supply tank 2A and the return tank 3A are connected via the communication flow path 9A, and the circulation valve 10A and the circulation pump 11A which are the opening and closing valves are provided in the communication flow path 9A. Further, in the present embodiment, the supply groove 2A and the return groove 3A are provided at the same height position above the ink jet head IJ. Further, at the lower end portion of the ink jet head IJ, a plurality of nozzles NZ are arranged at a fixed pitch in the lateral direction (the horizontal direction in the drawing).

Therefore, the coating liquid supplied from the supply tank 2A to the inkjet head IJ via the supply flow path 5A passes through the inside of the inkjet head IJ, and then returns to the return tank 3A via the return flow path 7A, and further passes through the return tank 3A via the return tank 3A. The flow path 9A is connected to the supply tank 2A, thereby constituting a circulation path of the coating liquid for the inkjet head IJ. In this case, when the coating liquid passes through the inside of the inkjet head IJ, a back pressure is generated on the back side of the nozzle NZ as shown in FIG. 7, whereby a meniscus MK is generated at the front end portion of the nozzle NZ, and in this state A part of the coating liquid is ejected from the nozzle NZ by the operation of the piezoelectric element, and the meniscus MK is again generated after the ejection.

Further, the replenishing tank 12A is provided on the upstream side of the supply tank 2A, the replenishing tank 12A and the supply tank 2A are connected via the replenishing passage 13A, and the supply valve 14A and the supply pump 15A which are the opening and closing valves are provided in the replenishing passage 13A. In the upper space 2Aa of the liquid surface of the coating liquid in the supply tank 2A, one end portion (lower end portion) of the atmospheric air flow passage 17A in which the atmosphere opening valve 16A is provided is provided, and the other end of the atmospheric circulation flow path 17A is provided. The upper part (upper end) leads to the atmosphere.

In the upper space 3Aa of the liquid surface of the coating liquid in the return tank 3A, one end portion (lower end portion) of the negative pressure flow passage 19A of the negative pressure valve 18A is provided in the middle, and the negative pressure flow passage 19A is provided. The other end (upper end) and negative pressure generation Device 20A is connected. In the present embodiment, the negative pressure generating device 20A is an ejector-type negative pressure generating device having a regulator having a structure for suppressing pulsation generated in the negative pressure. Further, a control flow path 21A for controlling the magnitude of the negative pressure is connected to the lower side than the negative pressure valve 18A in the negative pressure flow path 19A, and an auxiliary negative pressure valve which is an open/close valve is provided in the control flow path 21A. 22A and the pressure gauge 23A, the front end (upper end) of the control flow path 21A is closed. Moreover, the electric signal 23S from the pressure gauge 23A is sent to the negative pressure generating device 20A. Therefore, the magnitude of the negative pressure generated by the negative pressure generating device 20A is measured by the pressure gauge 23A, and control for setting the negative pressure to the target value is performed based on the measured value. Further, in order to control such a negative pressure, the pressure gauge 23A may be built in the negative pressure generating device 20A.

Further, the pressure value of the negative pressure introduced into the upper space 3Aa of the return tank 3A from the negative pressure generating passage 20A via the negative pressure flow passage 19A is set to a pressure value of a negative pressure, that is, the pressure value of the negative pressure corresponds to The sum of the pressure (the meniscus pressure) required to generate the meniscus MK at the nozzle NZ of the ink jet head IJ and the pressure (head pressure) corresponding to the head of the return tank 3A (the pressure added by both) . That is, the absolute value of the pressure value of the former is the same as the absolute value of the pressure value of the latter. Further, the head of the return groove 3A corresponds to the size indicated by the symbol P1 in the figure, that is, the height from the liquid surface of the return groove 3A to the tip end portion of the nozzle NZ of the inkjet head IJ, and the meniscus pressure and the The height dimension indicated by the symbol P2 in the figure corresponds. Further, the head is preferably from 300 mm to 500 mm, and the meniscus pressure is preferably based on atmospheric pressure and the negative pressure side is over -50 Pa.

Further, a semiconductor substrate and a glass are arranged directly under the inkjet head IJ. The object to be coated 24A such as a substrate, a resin substrate, or a metal substrate. In this case, the inkjet head IJ can be moved in the lateral direction, or the object to be coated 24A can be moved in the lateral direction.

Next, the operation of the inkjet coating liquid control device 1A of the first embodiment will be described.

The replenishing tank 12A is a large-capacity tank for replenishing the coating liquid to the supply tank 2A, and is supplied from the replenishing tank 12A via the replenishing flow path 13A to the supply tank 2A by the supply pump 15A being driven when the supply valve 14A is opened. Coating solution. When the liquid level of the coating liquid in the supply tank 2A reaches the upper limit position 2L1, the supply valve 14A is closed and the driving of the supply pump 15A is stopped, and the supply of the coating liquid from the replenishing tank 12A to the supply tank 2A is stopped. In this state, the coating liquid in the supply tank 2A is used in the inkjet head IJ, and when the liquid level of the coating liquid in the supply tank 2A reaches the lower limit position 2L2, the supply valve 14A is opened again. The supply pump 15A is driven to replenish the coating liquid from the replenishing tank 12A to the supply tank 2A. By repeating such an operation, the liquid level of the coating liquid in the supply tank 2A is maintained between the upper limit position 2L1 and the lower limit position 2L2.

Moreover, the negative pressure generating device 20A is set to generate a negative pressure corresponding to the sum of the meniscus pressure and the head pressure. Further, the following operations are performed by opening the negative pressure valve 18A, the head circulation valve 8A, the head supply valve 6A, and the atmosphere opening valve 16A from the state in which all the valves except the supply valve 14A and the auxiliary negative pressure valve 22A are closed. action.

The coating liquid in the supply tank 2A is supplied to the inkjet head IJ through the supply flow path 5A by its own weight, passes through the inside of the inkjet head IJ, and then passes through the return flow path 7A. It flows into the return slot 3A. The reason for this operation is that the upper space 3Aa of the liquid surface of the coating liquid in the return tank 3A is in communication with the negative pressure generating device 20A via the negative pressure flow passage 19A, and the pressure of the upper space 3Aa becomes A negative pressure corresponding to the sum of the meniscus pressure and the head pressure. Further, the negative pressure generating device 20A is configured to suppress (or completely eliminate) the pulsation generated in the generated negative pressure, and thus the pulsation does not occur in the coating liquid in the ink jet head IJ. During this operation, a meniscus MK having a shape as shown in FIG. 7 is formed at the tip end portion of the nozzle NZ of the inkjet head IJ. Thereby, the problem of dropping the coating liquid from the tip end portion of the nozzle NZ is avoided. Further, the coating liquid is appropriately discharged from the tip end portion of the nozzle NZ to the object 24A by the operation of the piezoelectric element, and is maintained at the tip end portion of the nozzle NZ before and after the discharge of the coating liquid. The state of the meniscus MK of the shape shown in FIG.

When a suitable amount of the coating liquid is ejected from the nozzle NZ, the coating liquid is continuously returned from the supply tank 2A to the return tank 3A, whereby the liquid level of the coating liquid in the return tank 3A reaches the upper limit position 3L1. When the circulation valve 10A is opened and the circulation pump 11A is driven, the liquid level of the coating liquid returned to the tank 3A is lowered. When the liquid level of the coating liquid in the return tank 3A reaches the lower limit position 3L2, the circulation valve 10A is closed and the driving of the circulation pump 11A is stopped. By repeating such an operation, the liquid level of the coating liquid in the return tank 3A is maintained between the upper limit position 3L1 and the lower limit position 3L2.

By performing the above operation, when the coating liquid passes through the inside of the inkjet head IJ, the meniscus MK is generated at the tip end portion of the nozzle NZ. In this case, negative pressure is generated The apparatus 20A generates a negative pressure corresponding to the sum of the meniscus pressure and the head pressure in the upper space 3Aa of the liquid level of the coating liquid in the return tank 3A, so that the shape of the meniscus MK is satisfied to block the nozzle NZ The front end drops the optimum shape of the coating liquid. In other words, the shape of the meniscus MK is defined as an optimum shape depending on the viscosity of the coating liquid, the flow path area of the nozzle NZ, and the height position of the return groove 3A, and the negative pressure generated by the negative pressure generating device 20A can be used. The variable control is performed based on the magnitude of the negative pressure measured by the pressure gauge 23A. Therefore, even when the viscosity of the coating liquid is changed, the flow path area of the nozzle NZ is changed, or the height position of the return groove 3A is changed, the meniscus MK which is always in the optimum shape can be generated.

Further, in the process of transporting the coating liquid from the supply tank 2A to the return tank 3A, the coating liquid passes through the ink jet head IJ in a circulating manner, so that the gas in the ink jet head IJ is always accompanied by the passing coating liquid. It is discharged to the outside. Thereby, the problem of ejecting from the nozzle NZ in a state where a gas is mixed in the coating liquid is avoided. Further, in the ink jet head IJ, the coating liquid passes through the vicinity of the nozzle NZ in a circulated manner, thereby preventing the bubble from adhering to the vicinity of the nozzle NZ, whereby the ejection failure of the nozzle NZ does not occur. In addition, as the coating liquid, 6 mPa can be used. s~50mPa. s, preferably 20mPa. s~50mPa. s high viscosity coating solution.

Further, in the first embodiment, the supply groove 2A and the return groove 3A are disposed at the same height position, but the height positions of the two grooves 2A and 3A may be different. Further, in the first embodiment, the return groove 3A is disposed above the inkjet head IJ, but the return groove 3A may be disposed below the inkjet head IJ.

Further, in the first embodiment, as the negative pressure generating device 20A, Although a negative pressure generating device having a regulator and an ejector type is used, any other negative pressure generating device having a structure for suppressing pulsation generated in the negative pressure may be used.

Further, in the first embodiment, the present invention is applied to the case where one ink jet head IJ is provided, but the present invention may be applied to a case where a plurality of ink jet heads IJ are provided.

Fig. 2 is a view showing a schematic configuration of an inkjet coating liquid control device 1B according to a second embodiment of the present invention. As shown in the figure, the inkjet coating liquid control device 1B has a single control groove 2B, and the control groove 2B and the inside of the inkjet head IJ are connected via the supply flow path 3B, and the writing flow path 3B is provided with an opening and closing function. The head of the valve is supplied to the valve 4B. Further, the control groove 2B is connected to the inside of the ink jet head IJ via the return flow path 5B, and the head circulation valve 6B which is an open/close valve is provided in the return flow path 5B. Further, at the lower end portion of the ink jet head IJ, a plurality of nozzles NZ are arranged at a fixed pitch in the lateral direction (the horizontal direction in the drawing).

Therefore, the coating liquid supplied from the control tank 2B to the inkjet head IJ via the supply flow path 3B passes through the inside of the inkjet head IJ, and then returns to the control groove 2B via the return flow path 5B, thereby constituting the inkjet. The circulation path of the coating liquid of the head IJ.

Further, a supplemental tank 7B is provided on the upstream side of the control tank 2B, the supplementary tank 7B and the control tank 2B are connected via the supplementary flow passage 8B, and the supply valve 10B and the supply pump 9B which are the opening and closing valves are provided in the supplementary flow passage 8B. In the upper space 2Ba of the liquid level of the coating liquid in the control tank 2B, one end portion (lower end portion) of the air circulation flow path 12B of the first air opening valve 11B is provided in the middle, and the atmospheric circulation flow path 12B is provided. The other end (upper end) leads to the atmosphere.

In this case, when the coating liquid passes through the inside of the inkjet head IJ, a back pressure is generated on the back side of the nozzle NZ as shown in FIG. 7, whereby a meniscus MK is generated at the front end portion of the nozzle NZ, and in this state A part of the coating liquid is ejected from the nozzle NZ by the operation of the piezoelectric element, and the meniscus MK is again generated after the ejection.

Further, a negative pressure pump unit 13B, which is a negative pressure member, is provided on the downstream side of the return flow path 5B than the head circulation valve 6B. The negative pressure pump unit 13B includes a unit case 14B, a motor 15B fixed to the downstream end portion of the unit case 14B, a shaft 16B inserted into the unit case 14B and rotated by the rotational driving force of the motor 15B, and The negative pressure pump 18B is disposed at the upstream end of the unit casing 14B and has an impeller 17B fixed to the upstream end of the shaft 16B. Further, in the unit casing 14B, an internal flow path 19B constituting a part of the return flow path 5B is provided, and the upstream end of the internal flow path 19B communicates with the upstream side portion 5Ba of the return flow path 5B, and the downstream of the internal flow path 19B The end communicates with the downstream side portion 5Bb of the return flow path 5B. In the above description, the "upstream side" means the lower side in the legend and the "downstream side" means the upper side in the illustration.

The upstream side portion 5Ba of the return flow path 5B communicates with the supply flow path 3B via the bypass flow path 20B, and the bypass flow path 20B is provided with a bypass valve 21B which is an open/close valve. In addition, the air flow channel 22B is connected to the communication portion between the upstream side portion 5Ba of the return flow path 5B and the bypass flow path 20B, and one end portion (the end portion on the air opening side) of the air flow channel 22B passes through the opening and closing valve. The second atmosphere opens the valve 23B and opens to the atmosphere. Further, one end of the control flow path 24B is connected to the lower side of the second atmosphere opening valve 23B in the atmospheric flow channel 22B, and is provided in the control flow path 24B. The pressure valve 25B and the pressure gauge 26B which are the opening and closing valves are placed, and the other end (upper end) of the control flow path 24B is closed. Further, the electric signal 26S from the pressure gauge 26B is sent to the negative pressure pump control unit 27B. Therefore, the negative pressure pump 18B measures the magnitude of the negative pressure of the coating liquid from the upstream side portion 5Ba of the return flow path 5B by the pressure gauge 26B, and the negative pressure pump control unit 27B performs the negative value based on the measured value. The pressure is set to the control of the target value.

Further, the pressure value of the negative pressure pump 18B for sucking the negative pressure of the coating liquid from the upstream side portion 5Ba of the return flow path 5B is a pressure value corresponding to the nozzle for the ink jet head IJ. The sum of the pressure (meniscus pressure) required by the NZ to generate the meniscus MK and the pressure (head pressure) corresponding to the head of the control tank 2B. That is, the absolute value of the pressure value of the former is the same as the absolute value of the pressure value of the latter. Further, the head of the control groove 2B corresponds to the size indicated by the symbol P1 in the figure, that is, the height from the liquid surface of the control groove 2B to the tip end portion of the nozzle of the inkjet head IJ, and the meniscus pressure and the figure The height dimension indicated by the symbol P2 corresponds. Further, the head is preferably from 300 mm to 500 mm, and the meniscus pressure is preferably based on atmospheric pressure and the negative pressure side is over -50 Pa.

Further, an object 28B such as a semiconductor substrate, a glass substrate, a resin substrate, or a metal substrate is arranged directly under the inkjet head IJ. In this case, the inkjet head IJ can be moved in the lateral direction, or the object to be coated 28B can be moved in the lateral direction.

Next, the operation of the inkjet coating liquid control device 1B of the second embodiment will be described.

The replenishing tank 7B is a large-capacity for replenishing the coating liquid to the control tank 2B. The tank is driven by the supply pump 9B when the supply valve 10B is opened, whereby the coating liquid is replenished from the replenishing tank 7B to the control tank 2B via the replenishing passage 8B. When the liquid level of the coating liquid in the control tank 2B reaches the upper limit position 2L1, the supply valve 10B is closed and the driving of the supply pump 9B is stopped, and the supply of the coating liquid from the replenishing tank 7B to the control tank 2B is stopped. In this state, the coating liquid in the control tank 2B is used in the inkjet head IJ, and when the liquid level of the coating liquid in the control tank 2B reaches the lower limit position 2L2, the supply valve 10B is opened again. The supply pump 9B is driven to replenish the coating liquid from the replenishing tank 7B to the control tank 2B. By repeating such an operation, the liquid level of the coating liquid in the control tank 2B is maintained between the upper limit position 2L1 and the lower limit position 2L2.

First, the first air opening valve 11B, the bypass valve 21B, the pressure valve 25B, and the second air opening valve 23B are controlled by opening the first valve except for the supply valve 10B and the pressure valve 25B. The coating liquid in the tank 2B rises from the middle of the supply flow path 3B through the bypass flow path 20B to the middle of the atmospheric circulation flow path 22B by its own weight. At this time, the height position of the coating liquid rising in the atmospheric flow channel 22B is the same height position as the liquid surface of the coating liquid in the control tank 2B, and also the height position of the coating liquid in the unit casing 14B. the same.

In this state, when the second air-opening valve 23B is closed and the negative pressure pump control unit 27B transmits the electric signal 27S to the motor 15B to drive the negative pressure pump 18B, the coating liquid in the control tank 2B is self-weighted from the supply flow path 3B. In the middle, the bypass flow path 20B is sucked into the negative pressure pump 18B from the upstream side portion 5Ba of the return flow path 5B. Then, the coating liquid sucked into the negative pressure pump 18B is ejected to the downstream side portion 5Bb of the return flow path 5B via the internal flow path 19B of the unit casing 14B, and returned to the control tank 2B. in. Thereby, the circulation of the coating liquid is started, that is, the internal flow path from the control tank 2B via the supply flow path 3B, the bypass flow path 20B, the upstream side portion 5Ba of the return flow path 5B, and the unit case 14B. 19B and the downstream side portion 5Bb of the return flow path 5B are returned to the control groove 2B. When the circulation of the coating liquid is started as described above, the negative pressure is gradually increased by the pressure gauge 26B. Further, when the value of the measured negative pressure becomes a value corresponding to the sum of the meniscus pressure and the head pressure, the negative pressure pump control unit 27B transmits an electric signal to the motor 15B based on the electric signal 26S from the pressure gauge 26B. 27S, whereby the number of revolutions of the impeller 17B of the negative pressure pump 18B is an optimum value. Thereby, the negative pressure pump 18B is configured to take a value of the negative pressure of the coating liquid from the upstream side portion 5Ba of the return flow path 5B to a set value.

At this point of time, the following operation is performed by closing the bypass valve 21B and opening the head supply valve 4B and the head circulation valve 6B. In other words, the coating liquid in the control tank 2B is supplied to the inkjet head IJ via the supply flow path 3B by its own weight, passes through the inside of the inkjet head IJ, and then returns to the control tank 2B via the return flow path 5B. In this case, the negative pressure pump 18B is configured to suppress (or completely eliminate) the pulsation generated in the negative pressure for drawing the coating liquid from the upstream side portion 5Ba of the return flow path 5B, and thus passes through the ink jet head IJ. No pulsation occurs in the coating liquid. During this operation, a meniscus MK having a shape as shown in FIG. 7 is formed at the tip end portion of the nozzle NZ of the inkjet head IJ. Thereby, the problem of dropping the coating liquid from the tip end portion of the nozzle NZ is avoided. Further, the coating liquid is appropriately discharged from the tip end portion of the nozzle NZ to the object to be coated 28B by the operation of the piezoelectric element, and is maintained at the tip end portion of the nozzle NZ before and after the discharge of the coating liquid. The state of the meniscus MK of the shape shown in FIG.

During the above-described operation, the negative pressure pump 18B applies a negative pressure corresponding to the sum of the meniscus pressure and the head pressure to the coating liquid sucked from the upstream side portion 5Ba of the return flow path 5B, and thus the meniscus MK The shape is an optimum shape that satisfies the condition for preventing the coating liquid from dripping from the tip end of the nozzle NZ. That is, the shape of the meniscus MK is defined as an optimum shape according to the viscosity of the coating liquid or the flow path area of the nozzle NZ, and further, the height position of the groove 2B, and the negative pressure generated by the negative pressure pump 18B can be The magnitude of the negative pressure measured by the pressure gauge 26B is variably controlled. Therefore, even when the viscosity of the coating liquid is changed, the flow path area of the nozzle NZ is changed, or the height position of the control groove 2B is changed, the meniscus MK which is always in the optimum shape can be generated.

Further, in the process in which the coating liquid circulates from the control tank 2B through the supply flow path 3B and the return flow path 5B, the coating liquid passes through the ink jet head IJ in a circulating manner, and thus the gas in the ink jet head IJ is supplied The passed coating liquid is discharged to the outside as it is. Thereby, the problem of ejecting from the nozzle NZ in a state where a gas is mixed in the coating liquid is avoided. Further, in the ink jet head IJ, the coating liquid passes through the vicinity of the nozzle NZ in a circulated manner, thereby preventing the bubble from adhering to the vicinity of the nozzle NZ, whereby the ejection failure of the nozzle NZ does not occur. In addition, as the coating liquid, 6 mPa can be used. s~50mPa. s, preferably 20mPa. s~50mPa. s high viscosity coating solution.

Further, in the second embodiment, the control groove 2B is disposed above the inkjet head IJ, but the control groove 2B may be disposed below the inkjet head IJ.

Further, in the second embodiment, the impeller type negative pressure pump is used as the negative pressure pump 18B, but it is configured to suppress the pulsation generated in the negative pressure. Negative pressure pumps can also be used for others.

Further, in the second embodiment, the present invention is applied to the case where one ink jet head IJ is provided, but the present invention may be applied to a case where a plurality of ink jet heads IJ are provided.

Fig. 3 is a view showing a schematic configuration of an inkjet coating liquid control device 1C according to a third embodiment of the present invention. As shown in the figure, the inkjet coating liquid control device 1C has a single control tank 2C, and has a supply flow path 3C for supplying the coating liquid to the inside of the inkjet head IJ from the control tank 2C. Further, at the lower end portion of the ink jet head IJ, a plurality of nozzles NZ are arranged at a fixed pitch in the lateral direction (the horizontal direction in the drawing). The supply flow path 3C includes one base supply flow path 3Ca that is connected to the control groove 2C at the upstream end, and branches from the base supply flow path 3Ca and leads to both end portions of the nozzle array direction (left-right direction) of the inkjet head IJ. Two branches are supplied to the flow path 3Cb. Further, a head supply valve 4C which is an opening and closing valve is provided in each of the two branch supply passages 3Cb.

Therefore, the coating liquid supplied to the inkjet head IJ from the control tank 2C via the base supply flow path 3Ca and the branch supply flow path 3Cb is supplied unilaterally to the plurality of nozzles NZ inside the inkjet head IJ, and thus the spray is formed. A non-circulating path of the coating liquid of the ink head IJ.

Further, the replenishing tank 5C is provided on the upstream side of the control tank 2C, the replenishing tank 5C and the control tank 2C are connected via the replenishing passage 6C, and the supply valve 7C and the supply pump 8C which are the opening and closing valves are provided in the replenishing passage 6C. In the upper space 2Ca of the liquid surface of the coating liquid in the control tank 2C, one end portion (lower end portion) of the atmospheric air flow passage 10C in which the atmosphere opening valve 9C is provided is provided, and the atmospheric circulation flow path 10C is provided. The other end (upper end) leads to the atmosphere.

Further, the upper space 2Ca of the liquid surface of the coating liquid in the control tank 2C is provided with one end portion (lower end portion) of the negative pressure flow passage 12C in which the negative pressure valve 11C is provided, and the negative pressure circulation flow path 12C The other end (upper end) is connected to the negative pressure generating device 13C. In the present embodiment, the negative pressure generating device 13C is an ejector-type negative pressure generating device having a regulator having a structure for suppressing pulsation generated in the negative pressure. Further, a control flow path 14C for controlling the magnitude of the negative pressure is connected to the lower side than the negative pressure valve 11C in the negative pressure flow path 12C, and an auxiliary negative pressure valve which is an open/close valve is provided in the control flow path 14C. 15C and the pressure gauge 16C, the front end (upper end) of the control flow path 14C is closed. Moreover, the electric signal 16S from the pressure gauge 16C is sent to the negative pressure generating device 13C. Therefore, the magnitude of the negative pressure generated by the negative pressure generating device 13C is measured by the pressure gauge 16C, and control for setting the negative pressure to the target value is performed based on the measured value. Further, in order to control such a negative pressure, the pressure gauge 16C may be built in the negative pressure generating device 13C.

The pressure value of the negative pressure introduced into the upper space 2Ca of the control tank 2C from the negative pressure generating passage 13C via the negative pressure flow passage 12C is set to a pressure value corresponding to that used for the ink jet. The nozzle NZ of the head IJ generates the sum of the pressure (meniscus pressure) required for the meniscus MK and the pressure (head pressure) corresponding to the head of the control tank 2C, that is, the added value. That is, the absolute value of the pressure value of the former is the same as the absolute value of the pressure value of the latter. Further, the head of the control groove 2C corresponds to the size indicated by the symbol P1 in the figure, that is, the height from the liquid surface of the control groove 2C to the tip end portion of the nozzle NZ of the inkjet head IJ, and the meniscus pressure and the In the picture The height dimension indicated by the symbol P2 corresponds. Further, the head is preferably from 300 mm to 500 mm, and the meniscus pressure is preferably from -50 Pa on the negative side with respect to the atmospheric pressure.

Therefore, the meniscus MK is generated at the tip end portion of the nozzle NZ of the inkjet head IJ by the operation of the negative pressure generating device 13C, and in this state, the coating liquid is ejected from the nozzle NZ by the operation of the piezoelectric element. After the ejection, the meniscus MK is again generated.

Further, the upper space 2Ca of the liquid surface of the coating liquid in the control tank 2C is opened to one end portion (lower end portion) of the pressurizing flow path 17C to which the pressing force acts on the upper space 2Ca, and the other of the pressurizing flow path 17C One end portion (upper end portion) is connected to a pressurizing device outside the drawing. Further, a head pressurizing valve 18C is provided in the pressurizing flow path 17C.

Therefore, in addition to the operation of the negative pressure generating device 13C, the meniscus is generated at the tip end portion of the nozzle NZ of the inkjet head IJ and the coating liquid is ejected from the nozzle NZ, and the pressure flow path is passed. 17C, the pressing force acts on the upper space 2Ca of the liquid surface of the coating liquid in the control tank 2C, whereby the discharge liquid is forcibly ejected from the nozzle NZ of the inkjet head IJ, and the bubbles inside the inkjet head IJ are passed through The nozzle NZ is discharged.

In addition, an object to be coated 19C such as a semiconductor substrate, a glass substrate, a resin substrate, or a metal substrate is arranged directly under the inkjet head IJ. In this case, the inkjet head IJ can be moved in the lateral direction, or the object to be coated The 19C can be moved in the lateral direction.

Next, the operation of the inkjet coating liquid control device 1C of the third embodiment will be described.

The replenishing tank 5C is a large-capacity tank for replenishing the coating liquid to the control tank 2C, and is driven by the supply pump 8C when the supply valve 7C is opened, thereby passing from the replenishing tank 5C to the control tank 2C via the replenishing flow path 6C. Replenish the coating solution. Moreover, in the control slot 2C When the liquid level of the inside coating liquid reaches the upper limit position 2L1, the supply valve 7C is closed and the driving of the supply pump 8C is stopped, and the supply of the coating liquid from the replenishing tank 5C to the control tank 2C is stopped. In this state, the coating liquid in the control tank 2C is used in the inkjet head IJ, whereby the supply valve 7C is opened again and supplied when the liquid level of the coating liquid in the control tank 2C reaches the lower limit position 2L2. The pump 8C is driven to replenish the coating liquid from the replenishing tank 5C to the control tank 2C. By repeating such an operation, the liquid level of the coating liquid in the control tank 2C is maintained between the upper limit position 2L1 and the lower limit position 2L2.

In addition, first, all the valves except the supply valve 7C and the auxiliary negative pressure valve 15C are closed, and the head supply valve 4C provided in each of the two branch flow paths 3Cb of the supply flow path 3C is opened and will be installed. When the head pressurizing valve 18C of the pressurizing flow path 17C is opened for a fixed period of time, the coating liquid is forcibly ejected from the nozzle NZ of the ink jet head IJ, and the air bubbles inside the ink jet head IJ are discharged through the nozzle NZ.

Next, in this state, the head pressurizing valve 18C is closed and the negative pressure valve 11C is opened, thereby performing the operation shown below. In other words, the coating liquid in the control tank 2C is supplied to the inkjet head IJ via the supply flow path 3C by its own weight, and the upper space 2Ca of the liquid surface of the coating liquid in the control tank 2C is passed through the negative pressure flow path 12C. The negative pressure generating device 13C is in a state of communication, and therefore the pressure of the upper space 2Ca becomes a negative pressure corresponding to the sum of the meniscus pressure and the head pressure. Further, the negative pressure generating device 13C is configured to suppress (or completely eliminate) the pulsation generated in the generated negative pressure, and therefore does not cause pulsation in the coating liquid supplied into the inkjet head IJ. In the period in which the operation is performed, the meniscus MK having the shape shown in FIG. 7 is formed at the tip end portion of the nozzle NZ of the inkjet head IJ, thereby avoiding the drop of the coating liquid from the tip end portion of the nozzle NZ. Happening. Further, the coating liquid is appropriately discharged from the tip end portion of the nozzle NZ to the object to be coated 19C by the operation of the piezoelectric element, and is maintained at the tip end portion of the nozzle NZ before and after the discharge of the coating liquid. The state of the meniscus MK of the shape shown in FIG.

By performing the above operation, when the coating liquid passes through the inside of the inkjet head IJ, a meniscus MK is formed at the tip end portion of the nozzle NZ, and the shape of the meniscus MK is satisfied to prevent the nozzle NZ from being blocked. The optimum shape of the conditions at which the coating liquid is dropped at the front end. In other words, the shape of the meniscus MK is defined as an optimum shape depending on the viscosity of the coating liquid, the flow path area of the nozzle NZ, and the height position of the groove 2C, and the negative pressure generated by the negative pressure generating device 13C can be used. The variable control is performed based on the magnitude of the negative pressure measured by the pressure gauge 16C. Therefore, even when the viscosity of the coating liquid is changed, the flow path area of the nozzle NZ is changed, or the height position of the control groove 2C is changed, the meniscus MK which is always in the optimum shape can be generated.

Further, in a fixed time period when the operation is not performed, the air bubbles inside the inkjet head IJ are discharged together with the coating liquid through the nozzle NZ by the action of the pressurized fluid from the pressure flow path 17C. external. Thereby, it is possible to avoid the problem of ejecting from the nozzle NZ in a state where air bubbles are mixed in the coating liquid. In addition, as the coating liquid, 6 mPa can be used. s~50mPa. s, preferably 20mPa. s~50mPa. s high viscosity coating solution.

Further, in the third embodiment, the control groove 2C is disposed above the inkjet head IJ, but the control groove 2C may be disposed below the inkjet head IJ.

Further, in the third embodiment, the negative pressure generating device 13C uses an ejector-type negative pressure generating device having a regulator, but The negative pressure generating device for the pulsating structure generated in the negative pressure may be other.

Further, in the third embodiment, the present invention is applied to the case where one ink jet head IJ is provided, but the present invention may be applied to a case where a plurality of ink jet heads IJ are provided.

Fig. 4 is a view showing a schematic configuration of an inkjet coating liquid control device 1D according to a fourth embodiment of the present invention. As shown in the figure, the inkjet coating liquid control device 1D has a single control tank 2D, and has a supply flow path 3D for supplying the coating liquid unidirectionally from the control tank 2D to the inside of the inkjet head IJ. Further, at the lower end portion of the ink jet head IJ, a plurality of nozzles NZ are arranged at a fixed pitch in the lateral direction (the horizontal direction in the drawing). The upstream side portion 3Da of the supply flow path 3D is a single flow path that is connected to the control groove 2D at the upstream end. On the other hand, the downstream side portion 3Db of the supply flow path 3D includes one base downstream side supply flow path 3Dc whose upstream end is connected to a negative pressure pump 16D to be described later, and branches from the base downstream side supply flow path 3Dc and respectively flow to the spray The two branch downstream side supply flow paths 3Dd at both ends of the nozzle array direction (left-right direction) of the ink head IJ. Further, a head supply valve 4D which is an opening and closing valve is provided in each of the two branch downstream side supply flow paths 3Dd.

Therefore, the coating liquid supplied to the inkjet head IJ from the control groove 2D via the upstream side portion 3Da and the downstream side portion 3Db of the supply flow path 3D is supplied to the inside of the inkjet head IJ unilaterally, and thus constitutes an inkjet A non-circulating path of the coating liquid of the head IJ.

Further, the replenishing tank 5D is provided on the upstream side of the control tank 2D, the replenishing tank 5D and the control tank 2D are connected via the replenishing passage 6D, and the supply valve 7D and the supply pump 8D which are the opening and closing valves are provided in the replenishing passage 6D. Further, the first atmosphere is opened in the middle of the upper space 2Da of the liquid surface of the coating liquid in the control tank 2D. One end portion (lower end portion) of the atmospheric circulation flow path 10D of the valve 9D, and the other end portion (upper end portion) of the atmospheric circulation flow path 10D is open to the atmosphere.

Further, between the upstream side portion 3Da and the downstream side portion 3Db in the supply flow path 3D, a negative pressure pump unit 11D which is a negative pressure member is provided. The negative pressure pump unit 11D includes a unit casing 12D, a motor 13D fixed to an upstream end portion of the unit casing 12D, a shaft 14D inserted into the unit casing 12D and rotated by a rotational driving force of the motor 13D, and The negative pressure pump 16D is disposed at the downstream end of the unit casing 12D and has an impeller 15D fixed to the downstream end of the shaft 14D. Further, in the unit casing 12D, an internal flow path 17D constituting a part of the supply flow path 3D is provided, and the upstream end of the internal flow path 17D communicates with the upstream side portion 3Da of the supply flow path 3D, and the downstream of the internal flow path 17D The end communicates with the trunk downstream side supply flow path 3Dc of the downstream side portion 3Db of the supply flow path 3D. In addition, in the above description, the "upstream side" means the upper side in the illustration, and the "downstream side" means the lower side in the illustration.

The lower end portion of the downstream side supply flow path 3Dc of the downstream side portion 3Db of the supply flow path 3D is connected to the atmospheric flow flow path 18D, and one end portion (end portion on the air opening side) of the atmospheric flow flow path 18D is used as an opening and closing valve. The second atmospheric opening valve 19D is open to the atmosphere. Further, one end of the control flow path 20D is connected to the lower side of the second air-opening valve 19D in the atmospheric flow channel 18D, and a pressure valve 21D and a pressure gauge 22D which are open-and-close valves are provided in the control flow path 20D. And the other end (upper end) of the control flow path 20D is closed. Further, the electric signal 22S from the pressure gauge 22D is sent to the negative pressure pump control unit 23D. Therefore, the negative pressure pump 16D is used by the pressure gauge 22D to draw the negative pressure of the coating liquid from the downstream side portion 3Db of the supply flow path 3D. The size of the negative pressure pump control unit 23D performs control for setting the negative pressure to the target value based on the measured value.

Further, the negative pressure pump 16D is for sucking the pressure value of the negative pressure of the coating liquid from the downstream side portion 3Db of the supply flow path 3D, and is set to a pressure value corresponding to that for the ink jet head IJ. The pressure (the meniscus pressure) required for the nozzle NZ to generate the meniscus MK is the sum of the pressure (head pressure) corresponding to the head of the control tank 2D. That is, the absolute value of the pressure value of the former is the same as the absolute value of the pressure value of the latter. Further, the head of the control groove 2D corresponds to the size indicated by the symbol P1 in the figure, that is, the height from the liquid surface of the control groove 2D to the tip end portion of the nozzle NZ of the inkjet head IJ, and the meniscus pressure and the The height dimension indicated by the symbol P2 in the figure corresponds. Further, the head is preferably from 300 mm to 500 mm, and the meniscus pressure is preferably based on atmospheric pressure and the negative pressure side is over -50 Pa.

Therefore, the meniscus MK is generated at the tip end portion of the nozzle NZ of the inkjet head IJ by the operation of the negative pressure pump 16D, and in this state, the coating liquid is ejected from the nozzle NZ by the operation of the piezoelectric element. The meniscus MK is again generated after the ejection.

Further, the upper space 2Da of the liquid surface of the coating liquid in the control tank 2D is opened to one end portion (lower end portion) of the pressurizing flow path 24D to which the pressing force acts on the upper space 2Da, and the other of the pressurizing flow path 24D One end portion (upper end portion) is connected to a pressurizing device outside the drawing. Further, a head pressure valve 25D is provided in the pressure flow path 24D.

Therefore, the time other than when the meniscus is generated at the tip end portion of the nozzle NZ of the ink jet head IJ and the coating liquid is ejected from the nozzle NZ by the operation of the negative pressure pump 16D is passed through the pressurizing flow path 24D. Applying pressure to the coating in the control tank 2D The upper space 2Da of the liquid level of the liquid is forcibly ejected from the nozzle NZ of the inkjet head IJ, and the air bubbles inside the inkjet head IJ are discharged through the nozzle NZ.

In addition, an object to be coated 26D such as a semiconductor substrate, a glass substrate, a resin substrate, or a metal substrate is arranged directly under the inkjet head IJ. In this case, the inkjet head IJ can be moved in the lateral direction, or the object to be coated The 26D can be moved in the lateral direction.

Next, the operation of the inkjet coating liquid control device 1D of the fourth embodiment will be described.

The replenishing tank 5D is a large-capacity tank for replenishing the coating liquid to the control tank 2D, and is supplied to the pump 8D when the supply valve 7D is opened, thereby passing from the replenishing tank 5D to the control tank 2D via the replenishing flow path 6D. Replenish the coating solution. When the liquid level of the coating liquid in the control tank 2D reaches the upper limit position 2L1, the supply valve 7D is closed and the driving of the supply pump 8D is stopped, thereby stopping the replenishment of the coating liquid from the replenishing tank 5D to the control tank 2D. In this state, the coating liquid in the control tank 2D is used in the inkjet head IJ, whereby the supply valve 7D is opened again and supplied when the liquid level of the coating liquid in the control tank 2D reaches the lower limit position 2L2. The pump 8D is driven to replenish the coating liquid from the replenishing tank 5D to the control tank 2D. By repeating such an operation, the liquid level of the coating liquid in the control tank 2D is maintained between the upper limit position 2L1 and the lower limit position 2L2.

In addition, first, when the valves other than the supply valve 7D and the pressure valve 21D are closed, the second atmospheric open valve 19D is opened, and the coating liquid rises from the control tank 2D to the atmosphere via the negative pressure pump 16D. The position of the rising end is the same height as the liquid surface in the control groove 2D (the upper end position of the head) from the lower position of the second atmosphere opening valve 19D in the flow path 18D, and is also related to the unit housing. The height of the coating liquid in 12D is the same.

In this state, the second air opening valve 19D is closed, the two head supply valves 4D are opened, and the head pressure valve 25D is opened for a fixed time, whereby the coating liquid is forcibly discharged from the nozzle NZ of the inkjet head IJ. Air bubbles inside the inkjet head IJ are discharged through the nozzle NZ.

When the head pressurizing valve 25D is closed from this state and the negative pressure pump control unit 23D transmits the electric signal 23S to the motor 13D to drive the negative pressure pump 16D, the following operation is performed. In other words, the coating liquid in the control tank 2D reaches the negative pressure pump 16D from the upstream side portion 3Da of the supply flow path 3D via the internal flow path 17D of the unit casing 12D, and further passes from the negative pressure pump 16D via the supply flow path 3D. The downstream side portion 3Db (the base downstream side supply flow path 3Dc and the branch downstream side supply flow path 3Dd) is supplied to the inkjet head IJ and ejected from the tip end portion of the nozzle NZ. In this case, the negative pressure pump 16D is configured to suppress (or completely eliminate) the pulsation generated in the negative pressure for drawing the coating liquid from the downstream side portion 3Db of the supply flow path 3D, and thus is supplied to the inkjet head IJ. No pulsation occurs in the coating liquid. During the operation, the coating liquid is appropriately discharged from the tip end portion of the nozzle NZ to the object to be coated 26D by the operation of the piezoelectric element, and is maintained before and after the discharge of the coating liquid. The tip end portion of the nozzle NZ is in a state in which the meniscus MK having the shape shown in Fig. 7 is generated. Thereby, the problem of dropping the coating liquid from the tip end portion of the nozzle NZ is avoided.

During the above-described operation, the negative pressure pump 16D applies a negative pressure corresponding to the sum of the meniscus pressure and the head pressure to the coating liquid sucked from the downstream side portion 3Db of the supply flow path 3D, and thus the meniscus MK Shape becomes satisfied to block The optimum shape of the conditions for dropping the coating liquid from the tip end of the nozzle NZ. That is, the shape of the meniscus MK is defined as an optimum shape according to the viscosity of the coating liquid or the flow path area of the nozzle NZ, and thus the height position of the groove 2D, and the negative pressure generated by the negative pressure pump 16D can be The magnitude of the negative pressure measured by the pressure gauge 22D is variably controlled. Therefore, even when the viscosity of the coating liquid is changed, the flow path area of the nozzle NZ is changed, or the height position of the control groove 2D is changed, the meniscus MK which is always in the optimum shape can be generated.

Further, in a fixed time period when the operation is not performed, the bubble inside the inkjet head IJ is discharged together with the coating liquid through the nozzle NZ by the action of the pressurized fluid from the pressure flow path 24D. external. Thereby, it is possible to avoid the problem of ejecting from the nozzle NZ in a state where air bubbles are mixed in the coating liquid. In addition, as the coating liquid, 6 mPa can be used. s~50mPa. s, preferably 20mPa. s~50mPa. s high viscosity coating solution.

Further, in the fourth embodiment, the control groove 2D is disposed above the inkjet head IJ, but the control groove 2D may be disposed below the inkjet head IJ.

Further, in the fourth embodiment, the impeller type negative pressure pump is used as the negative pressure pump 16D. However, any negative pressure pump having a structure for suppressing pulsation generated in the negative pressure may be used. .

Further, in the fourth embodiment, the present invention is applied to the case where one ink jet head IJ is provided, but the present invention may be applied to a case where a plurality of ink jet heads IJ are provided.

As described above, the spray according to the first to fourth embodiments In order to variably control the shape of the meniscus, the ink coating liquid control device can variably control the magnitude of the negative pressure generated by the negative pressure generating member, so that the shape of the meniscus can be easily performed. Fine-tuning and creating a meniscus that is always in the best shape.

Further, according to the specificity of the structure of the negative pressure generating member, the pulsation of the negative pressure acting on the coating liquid can be eliminated, so that the meniscus of the optimum shape can be produced in a stable state.

Claims (6)

An inkjet coating liquid control device comprising a supply flow path and a return flow path of a coating liquid to an inkjet head, and a control groove for connecting the flow paths and storing the coating liquid The circulation path of the coating liquid of the ink head, wherein the control tank includes: a supply tank that supplies a coating liquid to the inkjet head via a supply flow path, and the The supply tank is in communication and returns to the return tank of the coating liquid from the inkjet head via the return flow path, and the inkjet coating liquid control device includes a negative pressure generating member that generates a negative pressure corresponding to the spray a sum of a meniscus pressure at a nozzle of the ink head and a pressure corresponding to a head of the return tank, wherein the negative pressure generating member is configured to cause a negative pressure to act on the return tank, and the coating liquid is supplied After the supply tank reaches the inkjet head through the supply flow path, it passes through the inside of the inkjet head, then passes through the return flow path to reach the returning groove, and then passes back through the communication flow path. The supply tank, thereby constituting the circulation path, the inkjet The cloth liquid control device is configured to return air bubbles inside the ink jet head to the return groove via the return flow path while the coating liquid flows while circulating in the circulation path. The shape of the meniscus at the nozzle of the ink jet head is stabilized. The inkjet coating liquid control device according to the first aspect of the invention, wherein the negative pressure generating member is configured to suppress pulsation generated in a negative pressure. The inkjet coating liquid control device according to claim 1, wherein the negative pressure generating member is an ejector type negative pressure generating device having a regulator. An inkjet coating liquid control device comprising a supply flow path and a return flow path of a coating liquid to an inkjet head, and a control groove for connecting the flow paths and storing the coating liquid The circulation path of the coating liquid of the ink head, wherein the control tank is characterized in that the control tank is a single tank, and the single tank also serves to coat the inkjet head via the supply flow path. a liquid supply tank and a return tank returning from the inkjet head to the coating liquid via the return flow path, and the inkjet coating liquid control device includes a negative pressure generating member that generates a negative pressure corresponding to the a sum of a meniscus pressure at a nozzle of the inkjet head and a pressure corresponding to a head of the control tank, the coating liquid reaching the inkjet head from the control tank through the supply flow path Thereafter, passing through the inside of the inkjet head and then returning to the control groove through the return flow path, thereby forming the circulation path, and the negative pressure generating member is disposed in the middle of the return flow path The inkjet coating liquid control device is configured to be in the coating liquid During a period in which the circulation path flows while flowing, the air bubbles inside the inkjet head are returned to the control groove via the return flow path and the shape of the meniscus at the nozzle of the inkjet head is made. stable. The inkjet coating liquid control device according to Item 4, wherein the negative pressure generating member is configured to suppress pulsation generated in a negative pressure. The inkjet coating liquid control device according to Item 4, wherein the negative pressure generating member is an impeller type negative pressure pump.