JP4691943B2 - Bubble discharging method and droplet discharging method - Google Patents

Description

  The present invention relates to a droplet discharge device, a method for discharging bubbles in a liquid channel in the droplet discharge device, and a droplet discharge method in the droplet discharge device.

2. Description of the Related Art In recent years, droplet discharge devices such as inkjet printers that perform drawing by discharging various liquid materials as droplets onto a substrate have been widely used for paper printing and industrial pattern formation. The discharge head that discharges droplets has a fine channel (liquid material channel), one end of the channel leads to a supply device that supplies the liquid, and the other end of the channel is connected to a nozzle. Thus, a droplet is ejected from the nozzle by pressure generating means (for example, a piezoelectric actuator) formed in the vicinity of the nozzle.
Bubbles often flow into the flow path of the discharge head from the supply device, but if bubbles exist in the flow path, the bubbles absorb pressure or block the flow path. There is a risk of causing ejection failure. Therefore, a technique for removing the mixed bubbles in the droplet discharge device is very important.

The most common technique for removing the mixed bubbles is to seal the nozzle surface with a cap, etc., and use a suction pump connected to the cap to decompress the inside of the cap. It discharges (for example, patent document 1). In addition, there is one that pressurizes from the liquid material tank side and sucks the liquid material from the nozzle side to discharge bubbles (for example, Patent Document 2).
These techniques are for discharging bubbles, and in particular, the technique according to Patent Document 2 is capable of simultaneously applying pressure from the liquid tank side and suction from the head side. It is possible to increase the flow rate of the body.

JP-A-5-201027 JP 2000-313123 A

  However, some of the bubbles in the liquid channel are difficult to discharge. For example, the liquid flow path is configured by a liquid chamber provided for a specific function and a communication pipe communicating with the liquid chamber, but depending on the shape of the liquid chamber and the positional relationship with the communication port, There is also a place where the flow of the liquid material stagnates in the liquid chamber. The bubbles staying in such a place cannot be easily removed even if the flow rate of the liquid to be sucked is increased. In addition, a filter member is provided in the middle of the liquid material channel for the purpose of removing dust mixed in the liquid material, but bubbles cannot stay through the filter eyes. There is also a case.

With the technology according to the above-mentioned literature, it is difficult to reliably discharge such bubbles. Even so, if the bubbles are to be discharged, the flow rate of the discharged liquid must be very large, and the amount of the liquid discharged with the bubbles and discarded increases, which is uneconomical.
Therefore, there is a need for a technique that enhances the discharge of bubbles without depending on the flow rate of the discharged liquid, or that makes it difficult to cause a discharge failure even if bubbles remain in the liquid channel. .

  The present invention has been made in order to solve the above-described problems, and can control statically (without accompanying the flow of the liquid material) the discharge property of the bubbles and the influence of the discharge in the liquid material flow channel. Liquid droplet discharge device, bubble discharge method in the liquid droplet discharge device capable of easily discharging bubbles in the liquid material flow path, and liquid capable of making it difficult to cause defective discharge due to bubbles It aims at providing the droplet discharge method in a droplet discharge device.

  The present invention provides a discharge head in which nozzles are formed, a liquid flow path for supplying a liquid material from a liquid container to the discharge head, and a pressure control means capable of controlling the pressure of the atmosphere facing the nozzle opening. And back pressure control means capable of controlling the back pressure in the liquid material flow path, and controlling the atmospheric pressure so as to maintain an appropriate pressure difference with respect to the back pressure, It is characterized by a higher or lower pressure than that.

The liquid material flow path described here is, for example, a series of from the main flow path in the liquid material type section to the reservoir (temporary capacity chamber) in the nozzle row section, the supply path in the nozzle section, the pressure chamber, and the nozzle. It refers to the flow path.
When a liquid material is filled in such a series of flow paths, an interface between the liquid material and air, that is, a meniscus is formed in the opening of the nozzle. The state of the meniscus in the steady state is determined by the atmospheric pressure facing the nozzle opening, the back pressure at the meniscus position, the surface tension of the liquid material, the wettability between the liquid material and the nozzle inner surface, and the like. Here, the back pressure refers to the pressure (hydrostatic head) of the liquid material in the liquid material flow path. Usually, the back pressure is set slightly lower (on the negative side) than the atmospheric pressure (normally atmospheric pressure) facing the nozzle opening, and such a state is called a negative pressure state. By setting an appropriate negative pressure state, the meniscus is drawn into the deeper side of the nozzle (one end of the liquid material flow path), and an appropriate surface tension acts on the meniscus to achieve stable droplet ejection. That is why.

As described above, an appropriate negative pressure state is a prerequisite for stable droplet discharge. Even if droplets are not ejected, in order to keep the liquid material in a steady state in the liquid material flow path, the atmospheric pressure facing the nozzle opening and the back pressure in the liquid flow path are maintained at an appropriate pressure difference. There is a need. However, in the conventional droplet discharge device, since the atmospheric pressure facing the nozzle opening is fixed at atmospheric pressure, the back pressure can only be set based on the atmospheric pressure, and the back pressure as an absolute value can be freely set. It was equal to no degree.
In the droplet discharge device of the present invention, the atmospheric pressure facing the nozzle opening is controlled so as to maintain an appropriate pressure difference with respect to the back pressure, so that the liquid material does not flow or is appropriately negative. The absolute value of the back pressure can be changed while maintaining the pressure state. Then, the state (size) of the bubbles in the liquid channel can be changed by changing the absolute value of the back pressure. For example, by increasing the bubble size, it is possible to increase the bubble movement force associated with the flow of the liquid, or to reduce the bubble size, thereby reducing the bubble movement resistance or reducing the influence on the meniscus. . Thus, it is possible to statically change the bubble discharging property and the ejection influence degree without depending on the flow of the liquid. In the present invention, an appropriate pressure difference includes a state where there is no pressure difference.

The droplet discharge device includes an airtight container that accommodates the discharge head, and the atmospheric pressure control means is a means for controlling the atmospheric pressure in the airtight container.
According to the droplet discharge device of the present invention, it is possible to simply configure the atmospheric pressure control means by accommodating the discharge head in the airtight container.

  The droplet discharge device is characterized in that the liquid material in the liquid material channel is discharged from the nozzle following a state in which the back pressure is higher or lower than atmospheric pressure.

  According to the droplet discharge device of the present invention, the state (size) of bubbles in the liquid material flow path is controlled by changing the absolute value of the back pressure, and subsequently, the liquid material is discharged from the nozzle. The bubbles can be removed. For example, if the back pressure is increased to reduce the bubbles, the bubbles can be easily separated from the channel wall, or can easily pass through a fine filter and the like, and the bubbles can be easily discharged. Further, if the back pressure is lowered and the bubbles are enlarged, a large moving force is exerted by the flow of the liquid material, so that even the bubbles in the portion where the flow is stagnated are easily discharged. Thus, it is possible to reliably discharge bubbles without increasing the amount of the liquid material to be discarded.

  The droplet discharge device that discharges the liquid material from the nozzle includes a suction unit that sucks the liquid material in the liquid material channel from the nozzle via a cap member that can be in close contact with the opening surface of the nozzle. In the state where the back pressure is higher or lower than atmospheric pressure, the liquid material is discharged from the nozzle by the suction means.

As a method for discharging the liquid material from the nozzle, for example, a waste liquid receiving container is arranged facing the opening surface of the nozzle, and the air pressure of the airtight container is lowered with respect to the back pressure by the air pressure control means, or A method of increasing the back pressure with respect to the air pressure of the airtight container by the back pressure control means is conceivable. However, since the airtight container has a large capacity, it is not suitable for rapidly changing the pressure, and there are various back pressure control means, but this is also for the purpose of rapidly changing the pressure. Is unsuitable.
According to the droplet discharge device of the present invention, the capacity of the liquid material is sucked down by the cap member by reducing the pressure in the small-capacity space facing the nozzle opening surface. It is possible to control. Thus, it is possible to reduce the liquid discharge amount (waste liquid amount) required to discharge the bubbles.

  The droplet discharge device is characterized in that the droplet is discharged from the discharge head in a state where the back pressure is higher than atmospheric pressure.

  According to the droplet discharge device of the present invention, by increasing the absolute value of the back pressure, it is possible to discharge a droplet in a state where the bubbles in the liquid material channel are compressed to be small and perform desired drawing. Reducing the bubbles remaining in the liquid material flow path works favorably on factors that cause discharge failure such as absorption of pressure generated by the pressure generating means or blockage of the flow path. Generation can be reduced. Thus, high-definition drawing is possible.

  In the liquid droplet ejection apparatus, the back pressure control means is a means for controlling the atmospheric pressure of the atmosphere in direct contact with the liquid material in the liquid material container.

The pressure (hydrostatic head) of the liquid as back pressure includes an intrinsic component that depends on the expansion / compression of the liquid and a so-called position head that varies depending on the liquid level (depth) of the liquid. However, these components work equally as back pressure for both components. That is, as a method of changing the back pressure, the specific component may be changed or the position head component may be changed. In the former case, for example, a method of changing the liquid pressure in the liquid container is conceivable. In the latter case, for example, a method of changing the height (position with respect to the vertical direction) of the liquid container with respect to the nozzle opening surface is conceivable. It is done.
The back pressure control means in the droplet discharge device of the present invention is configured to change the atmospheric pressure of the atmosphere in direct or indirect contact with the liquid material in the liquid material container. Here, the atmosphere in direct contact refers to the atmosphere in direct contact with the liquid surface of the liquid in the liquid container. In addition, the indirectly contacting atmosphere refers to an atmosphere that is in contact with a liquid material and a flexible film so that pressure can be transmitted.
As the back pressure control means in the droplet discharge device of the present invention, specifically, for example, a configuration in which a liquid material container having an air communication port is accommodated in an airtight container and the internal pressure is changed is considered. It is done. Further, a configuration in which a liquid container in which a flexible sealed container is filled with a liquid material is accommodated in an airtight container and the atmospheric pressure in the container is changed is also conceivable.
According to the droplet discharge device of the present invention, both the atmospheric pressure control by the atmospheric pressure control means and the back pressure control by the back pressure control means are both controlled by the air pressure, and a part of the mechanism is shared. Therefore, a simple apparatus configuration can be obtained.

  In the droplet discharge device, the liquid in the liquid container and the atmosphere in the airtight container are in direct or indirect contact, and the back pressure control means and the atmospheric pressure control means are shared. It is characterized by.

  In the droplet discharge device of the present invention, the liquid in the liquid container and the atmosphere in the airtight container are in direct or indirect contact with each other, and the liquid pressure of the liquid is controlled by controlling the atmospheric pressure in the airtight container. That is, the back pressure can be controlled. That is, in this droplet discharge device, the atmospheric pressure control means and the back pressure control means are shared, and the configuration is very simple. In addition, since the atmospheric pressure and the back pressure can be controlled centrally, the control is also easy.

  The present invention relates to a method for discharging bubbles in a liquid material flow path that communicates a liquid material container with a discharge head in which a nozzle of a droplet discharge device is formed, and the atmospheric pressure and the liquid state facing the opening of the nozzle A static bubble control step that maintains a moderate pressure difference between the back pressure in the body flow path and sets the pressure to a state higher or lower than the atmospheric pressure, and a pressure difference between the pressure and the back pressure. And a dynamic bubble control step of generating and discharging the liquid material in the liquid material flow path from the nozzle.

  According to the bubble discharge method of the present invention, the atmospheric pressure facing the opening of the nozzle and the back pressure in the liquid channel are in a state where an appropriate pressure difference is maintained, and the absolute value thereof is higher than the atmospheric pressure. In addition, by setting the state of high pressure or low pressure, it is possible to control the state (size) of bubbles in the liquid channel without causing the liquid to flow. Furthermore, following this state, the liquid can be discharged from the nozzle to remove bubbles. Thus, it is possible to reliably discharge bubbles without increasing the amount of the liquid material to be discarded. In the present invention, an appropriate pressure difference includes a state where there is no pressure difference.

  In the static bubble control step, the bubble discharging method is configured such that after the atmospheric pressure and the back pressure are higher than the atmospheric pressure, the dynamic bubble control step is performed from the nozzle to the liquid channel. In the first step of discharging the liquid material and in the static bubble control step, the air pressure and the back pressure are lower than atmospheric pressure, and then in the dynamic bubble control step, the nozzle A second discharging step of discharging the liquid material in the liquid material flow path.

If bubbles remain in the liquid channel, increasing the back pressure to reduce the bubbles will make it easier for the bubbles to leave the channel wall or pass through a fine filter, etc. Is likely to be discharged. Further, if the back pressure is lowered and the bubbles are enlarged, a large moving force is exerted by the flow of the liquid material, so that even the bubbles in the portion where the flow is stagnated are easily discharged. Thus, depending on the position and original size of the bubbles, there are bubbles that are easily discharged when the back pressure is increased, and bubbles that are easily discharged when the back pressure is decreased.
In the bubble discharge method of the present invention, the former bubble can be discharged in the first discharge step, and the latter bubble can be discharged in the second discharge step, so that the bubbles in the liquid material channel can be discharged more reliably. Can do.

The bubble discharging method is characterized in that a plurality of times of the first discharging step and a plurality of times of the second discharging step are executed in combination.
In the bubble discharging method of the present invention, the bubbles are discharged by a combination of the first discharging step and the second discharging step a plurality of times, so that the bubbles in the liquid material channel can be discharged more reliably.

  According to the present invention, one end side of the liquid material channel formed in the discharge head communicates with the liquid material container, and the other end of the liquid material channel serves as a nozzle, and the liquid material is supplied from the liquid material container. A droplet discharge method in a droplet ejecting apparatus that discharges droplets from the nozzle, wherein the atmospheric pressure facing the opening of the nozzle and the back pressure in the liquid material flow path are in an appropriate negative pressure state. And a static bubble control step of maintaining a pressure higher than atmospheric pressure, and a discharge step of discharging the droplets from the nozzle after the static bubble control step. .

  According to the droplet ejection method of the present invention, by increasing the absolute value of the back pressure while maintaining a moderate negative pressure state, the droplets are ejected in a state where the bubbles in the liquid material channel are compressed to be small, Desired drawing can be performed. Reducing the bubbles remaining in the liquid material flow path works favorably on factors that cause discharge failure such as absorption of pressure generated by the pressure generating means or blockage of the flow path. Generation can be reduced. Thus, high-definition drawing is possible.

The bubble discharging method is performed in a recovery operation in the droplet discharge device.
In this way, a highly reliable recovery operation can be provided.

The droplet discharge method is performed in a drawing operation in the droplet discharge apparatus.
In this way, high-definition drawing is possible.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
The embodiment described below is a preferred specific example of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these forms.

(First embodiment)
(Main components of the droplet discharge device)
First, with reference to FIG. 1, FIG. 2, FIG. 3, FIG. 4, and FIG. FIG. 1 is a schematic perspective view showing a main part configuration of a droplet discharge device.
As shown in FIG. 1, the droplet discharge device includes a main body 101 and a liquid supply unit 104. The main body unit 101 includes a head mechanism unit 102 having a head unit 110 that ejects droplets, and a substrate mechanism unit 103 on which a substrate 120 that is an ejection target of droplets ejected from the head unit 110 is placed. .
As the substrate 120, a glass substrate, a metal substrate, a synthetic resin substrate, paper or the like can be used as long as it is a flat plate. Further, the substrate 120 does not need to be a strict flat plate shape, and a minute structure may be formed on the surface.

  The main body 101 includes a plurality of support legs 106 installed on the floor and a surface plate 107 installed on the upper side of the support legs 106. On the upper side of the surface plate 107, the substrate mechanism unit 103 is disposed over the longitudinal direction (X-axis direction) of the surface plate 107, and above the substrate mechanism unit 103, two columns fixed to the surface plate 107 are provided. The head mechanism unit 102 that is supported at both ends is arranged in a direction (Y-axis direction) orthogonal to the substrate mechanism unit 103. A maintenance unit 80 and a waste liquid tank 90 are disposed at a position on the front side of the head mechanism unit 102.

  The head mechanism unit 102 follows the head unit 110 that discharges the liquid material, the carriage 111 on which the head unit 110 is mounted, the Y-axis guide 113 that guides the movement of the carriage 111 in the Y-axis direction, and the Y-axis guide 113. The Y-axis ball screw 115, the Y-axis motor 114 for rotating the Y-axis ball screw 115 forward and backward, and the lower part of the carriage 111 are screwed with the Y-axis ball screw 115 to move the carriage 111. And a carriage screwing portion 112 in which a female screw portion is formed.

  The movement mechanism of the substrate mechanism unit 103 is arranged in the X-axis direction with a configuration substantially the same as that of the head mechanism unit 102, and an X for guiding the movement of the mounting table 121 and the mounting table 121 on which the substrate 120 is mounted. An axis guide 123, an X axis ball screw 125 installed along the X axis guide 123, an X axis motor 124 for rotating the X axis ball screw 125 forward and backward, and a lower part of the mounting table 121, the X axis ball It is comprised from the mounting base screwing part 122 which screws the screw | thread 125 and moves the mounting base 121. As shown in FIG.

  Although not shown, the head mechanism unit 102 and the substrate mechanism unit 103 are respectively provided with position detection means for detecting the positions where the head unit 110 and the mounting table 121 have moved. Further, the carriage 111 and the mounting table 121 incorporate a mechanism for adjusting the rotation direction with the Z axis as the rotation axis direction, and the rotation direction of the head unit 110 and the rotation direction of the mounting table 121 can be adjusted. . Furthermore, the carriage 111 also incorporates a mechanism that enables the head unit 110 to translate in the Z-axis direction.

  With these configurations, the head unit 110 and the substrate 120 can relatively move reciprocally in the Y-axis direction and the X-axis direction, respectively. The movement of the head portion 110 will be described. The Y-axis ball screw 115 rotates forward and backward by forward and reverse rotation of the Y-axis motor 114, and the carriage screwing portion 112 screwed to the Y-axis ball screw 115 becomes the Y-axis guide. By moving along 113, the carriage 111 integral with the carriage screwing portion 112 moves to an arbitrary position. That is, by driving the Y-axis motor 114, the head unit 110 mounted on the carriage 111 freely moves in the Y-axis direction. Similarly, the substrate 120 mounted on the mounting table 121 also moves freely in the X-axis direction.

  In this manner, the drive of the X-axis motor 124 and the Y-axis motor 114 can control the relative movement of the head unit 110 with respect to the substrate 120, and droplets can be ejected to any position on the substrate 120. A predetermined pattern can be drawn.

  The liquid supply unit 104 includes supply tubes 131a to 131c that form flow paths that communicate with the head unit 110, and liquid containers 130a to 130c that communicate with the supply tubes 131a to 131c and store the liquid material. . The reason why the three sets of tubes and liquid containers are provided in this way is to discharge different types of liquid materials onto the substrate 120. As liquids, materials containing functional materials such as light emitting materials such as organic EL (electroluminescence), fluorescent materials, color materials (pigments), and conductive materials are prepared depending on the purpose of drawing. The

  FIG. 2 is a plan view showing the arrangement of the ejection heads in the head unit. As shown in FIG. 2, the head unit 110 holds a plurality of ejection heads 116 having the same structure. The ejection head 116 for ejecting the liquid material as droplets has two nozzle rows extending in the Y-axis direction, and one nozzle row has, for example, 180 nozzles 117. The ejection heads 116 are arranged such that the nozzle positions (coordinates) in the Y-axis direction are offset at a predetermined interval.

FIG. 3 is a schematic perspective view showing the main structure of the ejection head. As shown in FIG. 3, the ejection head 116 includes a plurality of cavities 140 that are partitioned by partition walls 141, and one nozzle 117 is provided for each cavity 140. The nozzle 117 is formed on a nozzle plate 144 that is bonded and fixed to the lower surface of a member that constitutes the partition wall 141. The liquid material is supplied from the reservoir 145 to the cavity 140 via a supply port 146 located between the pair of partition walls 141. The reservoir 145 serves as a liquid reservoir for storing a certain amount of liquid material, and the liquid material is supplied to the reservoir 145 through the hole 147. Although not shown in the figure, the hole 147 communicates with the filter chamber 30 (see FIG. 7) for trapping foreign substances contained in the liquid material, and the head portion 110 (see FIG. 1) from the filter chamber 30. The supply tube 131 communicates with the flow path formed in.
Here, the filter chamber will be described with reference to FIG. The filter chamber 30 has a filter 31 formed by braiding metal into a mesh shape. Since the liquid material receives a large pressure loss when passing through the filter 31, the filter 31 has a larger diameter than the liquid material flow path 12 at the communicating portion in order to reduce the loss. A series of channels formed in the ejection head 116 including the nozzle 117, the cavity 140, the supply port 146, the reservoir 145, the hole 147, and the filter chamber 30 are hereinafter referred to as a liquid channel.

3 again, the upper part of the cavities 140 is a diaphragm 143, and the vibrators 142 as pressure generating means are positioned on the diaphragm 143 corresponding to the cavities 140. The vibrator 142 includes a piezoelectric element and a pair of electrodes (not shown) that sandwich the piezoelectric element. By applying a driving voltage to the pair of electrodes, the diaphragm 143 corresponding to the vibrator 142 is deformed, the internal pressure of the cavity 140 is changed, and the liquid material is ejected from the nozzle 117 as a droplet 150. Is done.
The drive voltage applied to the vibrator 142 is generated by a discharge control unit (not shown), and can be controlled (discharge control) so that droplets are discharged at an arbitrary timing for each nozzle 117. As described above, a predetermined pattern is formed on the substrate 120 (see FIG. 1) by synchronizing the drive control of the X-axis motor 124 and the Y-axis motor 114 (see FIG. 1) and the discharge control. Can be drawn.

Returning to FIG. 1 again, the maintenance unit 80 restores the discharge performance, for example, when the liquid material is filled into the liquid material channel (initial filling operation) or by removing foreign substances and bubbles in the liquid material channel. It is used when making (recovery operation) When a command for a filling operation and a recovery operation is sent to the droplet discharge device, the head unit 110 is moved to a position facing the maintenance unit 80 by the driving of the head mechanism unit 102 to perform a predetermined operation. .
The maintenance unit 80 includes waste liquid receiving means and wiping means. The waste liquid receiving means is a means for receiving the liquid material when the liquid material in the liquid material flow path is discharged via the nozzle 117 (see FIG. 3) of the head unit 110. The wiping means is a means for wiping and removing the liquid adhered to the surface of the nozzle plate 144 (see FIG. 3) after discharging the liquid.

FIG. 4 is a schematic sectional view showing a part of the maintenance unit, and particularly shows the structure of a cap unit as a waste liquid receiving means.
As shown in FIG. 4, a plurality of cap units 81 are arranged on the unit base 83 in accordance with the arrangement of the ejection heads 116 in the head portion 110 (see FIG. 2). The cap unit 81 includes a cap member 87 for sealing the space 92 facing the nozzle opening surface 118 of the ejection head 116, a receiver 88 for reinforcing the cap member 87, a spring 86 for pressing the receiver 88, Cap guides 85 and 89 that define the degree of freedom of movement of the receiver 88 are provided. When the head unit 110 is moved downward (Z-axis negative direction) by a translation mechanism (not shown in FIG. 1) provided in the carriage 111 (see FIG. 1), as shown in FIG. Further, the nozzle opening surface 118 is brought into contact with the cap member 87.
The cap member 87 is formed by molding an elastic body such as an elastomer so as to ensure adhesion with the nozzle opening surface 118. A communication port is formed at the bottom of the cap member 87, and one end of the waste liquid tube 84 is inserted into the communication port, and the other end side of the waste liquid tube 84 communicates with the waste liquid tank 90 (see FIG. 1). Thus, the liquid discharged from the nozzles of the ejection head 116 into the space 92 is accommodated in the waste liquid tank 90 via the waste liquid tube 84. A method of discharging the liquid material from the nozzles of the discharge head 116 will be described later.

(Overall configuration of droplet discharge device)
FIG. 5 is a schematic configuration diagram showing the overall configuration of the droplet discharge device. In the following description, the liquid supply section 104 is represented by the liquid container 130a and the supply tube 131a, and the liquid flow path 12 is branched corresponding to the plurality of ejection heads 116 and the plurality of nozzles 117. The flow path is not considered, and it is handled by being represented by one flow path formed corresponding to one nozzle.
As shown in FIG. 5, the droplet discharge device 1 stores the main body 101 and the liquid supply unit 104 shown in FIG. 1, the first chamber 13 and the second chamber 14 as airtight containers, and compressed air. The high-pressure tank 17, a vacuum tank 18 as a vacuum source, and vent pipes 21 a to 21 f for these pipes are configured.

In FIG. 5, the main body 101 is accommodated in the first chamber 13, and the liquid material container 130 a is accommodated in the second chamber 14. The liquid material flow path 12 formed in the discharge head 116 of the main body 101 is communicated with the outlet 24 provided near the bottom of the liquid material container 130a accommodated in the second chamber 14 via the supply tube 131a. ing.
The high-pressure tank 17 is communicated with the compressor 15 and the vent pipe 21 f and stores compressed air generated by the compressor 15. The compressor 15 is connected to a pressure control device 23 and controlled so that the high-pressure tank 17 always maintains a constant high-pressure state. The vacuum chamber 18 is communicated with the vacuum pump 16 by a communication pipe 21e, and the internal air is exhausted by the vacuum pump 16 to serve as a vacuum source. The vacuum pump 16 is connected to the pressure controller 23 and controlled so that the vacuum chamber 18 always maintains a constant vacuum state (depressurized state).

  The first chamber 13 is communicated with the high-pressure tank 17 by a vent pipe 21a, and an open / close valve 22a is provided in the middle of the vent pipe 21a. The first chamber 13 is communicated with the vacuum chamber 18 by a vent pipe 21b, and an open / close valve 22b is provided in the middle of the vent pipe 21b. Further, the first chamber 13 is provided with an atmospheric pressure sensor 19 for detecting the internal atmospheric pressure. The atmospheric pressure sensor 19, the opening / closing valve 22 a, and the opening / closing valve 22 b are connected to the pressure control device 23, and the opening / closing control of the opening / closing valve 22 a and the opening / closing valve 22 b is performed with reference to the detection value of the atmospheric pressure sensor 19, thereby The atmospheric pressure inside can be freely controlled. That is, the above-described configuration including the first chamber 13, the high pressure tank 17, the vacuum tank 18, the atmospheric pressure sensor 19, the opening / closing valve 22 a, the opening / closing valve 22 b, and the pressure control device 23 is an atmospheric pressure control unit.

  The second chamber 14 communicates with the high-pressure tank 17 by a vent pipe 21c, and an open / close valve 22c is provided in the middle of the vent pipe 21c. The second chamber 14 is communicated with the vacuum chamber 18 by a vent pipe 21d, and an open / close valve 22d is provided in the middle of the vent pipe 21d. Further, the second chamber 14 is provided with an atmospheric pressure sensor 20 for detecting the internal atmospheric pressure. The atmospheric pressure sensor 20, the on-off valve 22c, and the on-off valve 22d are connected to the pressure control device 23, and the second chamber 14 is controlled by opening / closing the on-off valve 22c and the on-off valve 22d with reference to the detection value of the atmospheric pressure sensor 20. The atmospheric pressure inside can be freely controlled.

Here, the dynamics of the liquid 11 in the flow path from the liquid flow path 12 to the liquid container 130a will be described.
As shown in FIG. 5, when the liquid material 11 is filled in a series of flow channels from the liquid material flow channel 12 to the liquid material container 130a, the opening of the nozzle 117 has an interface between the liquid material 11 and the air, that is, A meniscus 10 is formed. The state of the meniscus 10 at this time is the pressure P1 of the atmosphere (air in the first chamber 13 in this embodiment) facing the nozzle opening surface 118, the back pressure P4 in the meniscus 10, and the surface tension of the liquid 11 It is determined by the physical relationship such as wettability between the liquid 11 and the nozzle inner wall. Here, the back pressure refers to the pressure (hydrostatic head) of the liquid material in the liquid material flow path 12.
The back pressure P4 in the meniscus 10 is determined by the liquid pressure P3 at the position of the liquid level 28 of the liquid 11 in the liquid container 130a and the liquid level difference h of the liquid level 28 with respect to the nozzle opening surface 118. That is, the back pressure P4 is given by the following equation (1).
P4 = P3-hρg (1)
Here, ρ represents the density of the liquid material 11, and g represents the acceleration of gravity. As shown in the equation (1), the back pressure P4 includes an intrinsic component (P3) that depends on expansion / compression of the liquid 11 and a so-called position head component (hρg) that depends on the liquid level (depth) of the liquid 11. ).

In the case of the present embodiment, as shown in FIG. 5, an atmosphere communication port 25 is provided in the upper part of the liquid material container 130a, and the liquid level 28 is in direct contact with the air inside the second chamber 14. It has become. For this reason, the hydraulic pressure P3 is equal to the atmospheric pressure P2 in the second chamber 14, and the back pressure P4 can be further expressed by the following equation (2).
P4 = P2-hρg (2)
As shown in Expression (2), the back pressure P4 in the meniscus 10 can be controlled by the atmospheric pressure P2 in the second chamber 14. The atmospheric pressure P2 in the second chamber 14 can be controlled by the above-described configuration including the high-pressure tank 17, the vacuum tank 18, the atmospheric pressure sensor 20, the opening / closing valve 22c, the opening / closing valve 22d, and the pressure control device 23. That is, these configurations including the second chamber 14, the atmosphere communication port 25, the high pressure tank 17, the vacuum tank 18, the atmospheric pressure sensor 20, the opening / closing valve 22 c, the opening / closing valve 22 d, and the pressure control device 23 serve as back pressure control means. Fulfills the function.

Here, the state of the meniscus 10 (liquid body 11) when the pressure difference between the atmospheric pressure P1 and the back pressure P4 is small will be considered. For example, when the pressure P1 of the first chamber and the pressure P2 of the second chamber are in the atmospheric pressure state, for example, the back pressure P4 in the meniscus 10 is equal to the pressure of the first chamber by the position head component (hρg). It becomes lower than P1. At this time, the meniscus 10 has a curved surface as shown in FIG. 5 due to the surface tension of the liquid 11 and the wettability with the inner wall of the nozzle 117, and the meniscus 10 has an appropriate surface tension. Balance with pressure difference (hρg) and maintain steady state. Creating such a meniscus state is important for realizing stable droplet ejection.
In the meniscus 10, the fact that the back pressure P4 is smaller than the atmospheric pressure P1 is called a negative pressure state because the back pressure P4 is smaller than the atmospheric pressure P1, that is, a negative state. In order to discharge droplets stably, it is necessary to be in an appropriate negative pressure state, and for example, a range of P4-P1 = −300 Pa to −600 Pa is preferable. In this embodiment, the position head component (hρg) is set to be within this range, and when P1 = P2, P4-P1 = −hρg = −400 Pa, and the optimum negative pressure state Become. The range of the negative pressure state indicates a preferable condition for stably discharging droplets, and indicates a condition for maintaining the meniscus 10 and the liquid material 11 in a steady state. is not. Even if the back pressure P4 is a positive pressure (P4-P1> 0), the steady state can be maintained as long as the pressure difference is small. Further, the back pressure P4 changes with a decrease in the remaining amount of the liquid material 11 accommodated in the liquid material container 130a. At this time, by changing the pressure P2 in the second chamber 14, the amount of the change is reduced. Can be compensated.

In the droplet discharge device 1 according to the present embodiment, the pressure P1 and the back pressure P4 can be freely controlled by the pressure control device 23. In the range where the difference between the atmospheric pressure P1 and the back pressure P4 is small, the meniscus 10 and the liquid material 11 maintain the steady state as described above, but the range where the difference between the atmospheric pressure P1 and the back pressure P4 can maintain the steady state. When it becomes larger than this, the meniscus 10 can no longer maintain a stable shape, and the liquid 11 flows.
Such a flow of the liquid 11 is actively used, for example, when performing a recovery operation. That is, in FIG. 5, when the cap member 87 is brought into close contact with the nozzle opening surface 118 of the discharge head 116 and the pressure control device 23 controls the back pressure P4 to be higher than the atmospheric pressure P1, the pressure difference causes a liquid state. The body 11 is discharged from the nozzle 117 toward the inside of the cap member 87. At this time, bubbles and foreign matter in the liquid channel 12 are discharged together with the discharge of the liquid 11, and the discharge head 116 can perform normal discharge again. The discharged liquid 11 is stored as the waste liquid 29 in the waste liquid tank 90 through the waste liquid tube 84.

  Thus, whether the liquid 11 in the liquid flow path 12 is in a steady state or a fluid state is determined by the pressure difference between the atmospheric pressure P1 and the back pressure P4. It does not depend on the value. On the contrary, what is closely related to the absolute values of the atmospheric pressure P1 and the back pressure P4 is the state of the bubbles in the liquid material flow path 12 described below.

(Recovery action)
FIG. 6 is a schematic cross-sectional view showing the state of bubbles in the liquid material flow path, and shows the bubbles remaining around the cavity of the ejection head. FIG. 7 is a schematic cross-sectional view showing the state of bubbles in the liquid channel, and shows the bubbles remaining in the filter chamber of the ejection head. FIG. 8 is a diagram illustrating changes in the atmospheric pressure in the first chamber and the back pressure in the liquid material flow path during the recovery operation, where the solid line indicates the change in the atmospheric pressure P1 and the broken line indicates the change in the back pressure P4.
Hereinafter, the recovery operation will be described along the time axis in FIG. 8 with reference to FIGS. 5, 6, and 7. As described above, the recovery operation is an operation for removing the foreign matters and bubbles in the liquid material flow path to recover the discharge performance, and is performed using the maintenance unit 80 of FIG.

In FIG. 5, in the initial state (step S0 in FIG. 8), the pressure P1 in the first chamber 13 and the pressure P2 in the second chamber 14 are set to atmospheric pressure. As already described, the back pressure P4 at the position of the meniscus 10 is controlled via the atmospheric pressure P2, and the back pressure P4 at this time is a value lower by hρg than the atmospheric pressure P1. .
In step S <b> 0, as shown in FIGS. 6 and 7, the bubbles 32, 34, and 35 stay in the liquid material channel 12. The bubbles 32, 34, and 35 shown here indicate bubbles that are difficult to be removed by discharging the liquid material among the bubbles in the liquid material flow path 12. For example, the bubbles 32 stick to the side wall of the reservoir 145. It is difficult to move because it is in a state. Further, the bubbles 34 and 35 are located at the outer edge of the filter chamber 30, and it is difficult to pass through the filter 31 because the flow rate of the liquid material is small.

  When the recovery operation is started, the atmospheric pressure P1 and the back pressure P4 are lowered while maintaining the pressure difference = hρg, and are eventually maintained in the vicinity of PSL1 (step S1 in FIG. 8). In this step S1, the liquid 11 is maintained in a steady state (non-flowing state), but there is a change in the bubbles in the liquid flow path 12, and in FIG. The state shown in 34 ′ is obtained. In this way, by changing the pressure P1 and the back pressure P4 while maintaining an appropriate pressure difference, it is possible to change the state of the bubbles while maintaining the liquid material 11 in a steady state. In other words, the bubbles are statically controlled without the liquid material 11 flowing. For this reason, this step is called a static bubble control step. In the static bubble control step of the recovery operation, an appropriate pressure difference between the atmospheric pressure P1 and the back pressure P4 refers to a pressure difference within a range where the liquid material 11 maintains a steady state (non-flowing state). It also includes a state where there is no pressure difference.

After the static bubble control step S1, the back pressure P4 is increased to near atmospheric pressure while the pressure P1 is maintained at PSL1, and the liquid 11 flows due to the pressure difference and is discharged from the nozzle 117 (FIG. 8). Step S2). At this time, since the bubbles 34 ′ in FIG. 7 are blocked with a large area on the surface of the filter 31, a large pressure difference is generated between the upstream side and the downstream side of the filter 31. Due to this pressure difference, the bubble 34 ′ can pass through the filter 31. In this way, the step of trying to move the bubbles on the flow of the liquid 11 is referred to as a dynamic bubble control step with respect to the previous static bubble control step.
Eventually, the atmospheric pressure P1 is also increased to atmospheric pressure, and when the pressure difference between the atmospheric pressure P1 and the back pressure P4 decreases, the flow of the liquid 11 stops and becomes a steady state again. The atmospheric pressure P1 and the back pressure P4 are maintained near the atmospheric pressure while maintaining the pressure difference of hρg (waiting step S3 in FIG. 8).
Depending on the discharge amount in the dynamic bubble control step S <b> 2, the above-described bubble 34 ′ may not reach the outside of the nozzle 117 after passing through the filter 31. However, even in such a case, the bubbles 34 ′ are surely discharged from the nozzle 117 by a plurality of subsequent discharge steps.

Next, the atmospheric pressure P1 and the back pressure P4 are increased while substantially maintaining the pressure difference = hρg, and are eventually maintained in the vicinity of PSH1 (step S4 in FIG. 8). In this step S4, the liquid material 11 is maintained in a steady state, but there is a change in the bubbles in the liquid material flow path 12, and in FIG. 6, the bubbles 32 are contracted and shown in 32 '. It becomes. In FIG. 7, the bubble 35 contracts to a state indicated by a bubble 35 ′. That is, this step S4 is also a static bubble control step. The difference from the static bubble control step S1 is the difference in whether the back pressure P4 (atmospheric pressure P1) is smaller or larger than the atmospheric pressure, and the difference in whether the bubbles in the liquid flow channel 12 expand or contract.
In the static bubble control step S 4, the bubble 32 ′ in FIG. 6 can be easily moved away from the side wall of the reservoir 145. Further, the bubbles 35 ′ in FIG. 7 are contracted very small so that the eyes of the filter 31 can pass through with a slight force.

After the static bubble control step S4, the back pressure P4 is maintained in the vicinity of PSH1, while the pressure P1 exceeds the atmospheric pressure and is lowered to PSL1, and the liquid 11 flows due to the pressure difference and is discharged from the nozzle 117. (Dynamic bubble control step S5 in FIG. 8). In the static bubble control step S <b> 4, the bubbles 32 ′ and the bubbles 35 ′ that are easily moved can be easily moved on the flow of the liquid 11.
After a predetermined time has passed, the back pressure P4 is lowered this time, and when the pressure difference between the pressure P1 and the back pressure P4 becomes small, the flow of the liquid 11 stops, and the pressure P1 and the back pressure P4 maintain the pressure difference of hρg. It is maintained near PSL1 (static bubble control step S6 in FIG. 8).

  In this embodiment, following the static bubble control step S6 near PSL1, dynamic bubble control step S7, standby step S8 near atmospheric pressure, static bubble control step S9 near PSH2, dynamic bubble The control step S10, the standby step S11 in the vicinity of the atmospheric pressure is executed. Thereafter, the liquid material adhering to the surface of the nozzle plate 144 (see FIG. 3) is wiped away by the wiping means (step S12 in FIG. 8), and a series of recovery operations is completed.

  As described above, by executing the static bubble control step and the dynamic bubble control step in combination, bubbles that are difficult to be discharged only by the dynamic bubble control step (discharge of the liquid material) (for example, the bubbles 32 and 34). , 35) can be easily discharged. In the static bubble control step, it is better to expand or contract the bubbles, that is, whether it is better to lower or increase the back pressure. Therefore, it is preferable to use these in combination. That is, after the atmospheric pressure P1 and the back pressure P4 are made higher than the atmospheric pressure in the static bubble control step, the first discharge step of discharging the liquid material 11 in the dynamic bubble control step, and the atmospheric pressure P1 and After the back pressure P4 is made lower than the atmospheric pressure, the bubbles are more reliably discharged by executing in combination with the second discharge step of discharging the liquid material 11 from the nozzle in the dynamic bubble control step. Become. More preferably, bubbles can be discharged more reliably by combining a plurality of first discharge steps and a plurality of second discharge steps as in this embodiment.

  For example, in the technique according to Patent Document 2, the liquid material can be sucked from the nozzle side, the liquid material can be supplied under pressure, and the liquid material is discharged in a state where the back pressure is higher than the atmospheric pressure. Then, it can be said that it is not different from this embodiment. However, in such a technique, the pressure loss in the liquid material flow path is generated by the flow of the liquid material, so that the back pressure around the bubbles cannot be sufficiently increased. Moreover, since discharge | emission of a liquid body is necessarily accompanied, a liquid body will be discarded uselessly. On the other hand, in the present embodiment, the back pressure in the liquid material flow path 12 can be changed while maintaining the steady state, that is, without the flow of the liquid material 11, so that the state of the bubbles is surely maintained. It can be controlled, and the liquid material is not discarded unnecessarily. And, in this way, if the bubble discharge property is enhanced by the static bubble control step, the bubbles can be discharged at a slight flow rate. Can be reduced.

  Note that the values of the atmospheric pressure P1 and the back pressure P4 controlled in the static bubble control step (for example, PSH1, PSH2, PSL1) and the combinations thereof are not restricted by the aspect of the present embodiment, and the liquid material channel The structure can be optimally designed according to the structure of the liquid material supply unit 104 (see FIG. 1). Further, the pressure difference between the atmospheric pressure P1 and the back pressure P4 generated in the dynamic bubble control step and the time for generating the pressure difference (these are related to the discharge amount of the liquid material) are also restricted by the aspect of this embodiment. Instead, it can be optimally designed depending on the structure of the liquid material flow path and the structure of the liquid material supply unit 104 (see FIG. 1). The same applies to the order and combination of the first discharge step and the second discharge step. Furthermore, in the initial state (step S0) and the wiping operation (step S12) in the recovery operation, the atmospheric pressure P1 does not necessarily need to be atmospheric pressure.

(Drawing operation)
FIG. 9 is a diagram showing changes in the atmospheric pressure in the first chamber and the back pressure in the liquid material flow path in the drawing operation, where the solid line shows the change in the atmospheric pressure P1, and the broken line shows the change in the back pressure P4. Hereinafter, the drawing operation of the droplet discharge device will be described along the time axis of FIG. 9 with reference to FIG.
In FIG. 9, in the initial state (step S20 in FIG. 9), the atmospheric pressure P1 is lower than the atmospheric pressure, and the back pressure P4 is lower than the atmospheric pressure by hρg. This step S20 is a state in which the liquid material 11 is filled in the liquid material flow path 12 of the ejection head 116 in FIG. 5, and may be continued to the recovery operation (FIG. 8) described above or not at all. It may be in an independent state.

  From this state, the atmospheric pressure P1 and the back pressure P4 are increased while maintaining the pressure difference = hρg, and are eventually maintained in the vicinity of PSH3 (step S21 in FIG. 9). In step S <b> 21, the liquid body 11 maintains a steady state. However, when the bubbles in the liquid body channel 12 are changed, and bubbles remain in the liquid body channel 12, such bubbles are Compressed. That is, it can be said that this step S21 is a static bubble control step.

After the static bubble control step S21, drawing is performed by discharging droplets from the discharge head 116 while moving the discharge head 116 relative to the substrate 120 (see FIG. 1) (step S22 in FIG. 9).
At this time, the back pressure P4 is maintained in an appropriate negative pressure state (pressure difference between the pressure P1 and the back pressure P4 = hρg) under the control of the pressure control device 23, so that stable droplet discharge is possible. It is. That is, in the static bubble control step S21 of this drawing operation, the appropriate pressure difference between the atmospheric pressure P1 and the back pressure P4 refers to the range of the appropriate back pressure that allows stable ejection. In addition, when the liquid droplet is discharged, the bubbles remaining in the liquid channel 12 usually absorb the pressure generated in the cavity 140 by the vibrator 142 (see FIG. 3), or the liquid channel 12 However, in the present embodiment, the bubbles in the liquid material flow path 12 are compressed and made into a small state, and thus a discharge failure occurs. Hard to do.
As can be seen from the above description, after the bubbles in the liquid material flow path 12 are compressed by the static bubble control step, the liquid droplets are discharged from the nozzle 117 and drawn, thereby generating a discharge failure. Can be reduced and high-definition drawing can be performed. In addition, since the first chamber 13 that accommodates the substrate is maintained at a high pressure, minute bubbles contained in the liquid droplets do not have an adverse effect even after landing on the substrate.

(Second Embodiment)
FIG. 10 is a schematic configuration diagram illustrating the overall configuration of the droplet discharge device according to the second embodiment. Hereinafter, the description of the same parts as those in the first embodiment (FIG. 5) will be omitted, and the second embodiment will be described focusing on the differences.

In the droplet discharge device 1 of FIG. 10, the main body 101 is accommodated in the first chamber 13 and the liquid container 39 is accommodated in the second chamber 14, as in the first embodiment (FIG. 5). The first chamber 13 and the second chamber 14 are communicated with each other by a vent pipe 36a, and the vent pipe 36a has a vent pipe 36b and a vent pipe 36c which are branched pipes. An air pressure sensor 37 is provided inside the ventilation pipe 36a. The vent pipe 36b is in communication with the high-pressure tank 17 through an open / close valve 38a, and the vent pipe 36c is in communication with the vacuum tank 18 through an open / close valve 38b. The atmospheric pressure sensor 37, the open / close valve 38a, and the open / close valve 38b are connected to the pressure control device 23, and the open / close valve 38a and the open / close valve 38b are controlled to open / close with reference to the detection value of the atmospheric pressure sensor 37, thereby allowing the first chamber 13 to open / close. The internal pressure P1 and the internal pressure P2 in the second chamber 14 can be freely controlled.
As described above, the pressure P1 and the pressure P2 can always be controlled to be equal to each other by connecting the first chamber 13 and the second chamber 14 with the vent pipe 36a. The same pressure control is possible even if the main body 101 and the liquid material container 39 are accommodated in one airtight container without being accommodated in the first chamber 13 and the second chamber 14 separately. is there.

The liquid container 39 is formed by forming a flexible plastic film into a flat bag shape and attached with a lead-out port 42, and the liquid body 11 is accommodated therein. That is, the hydraulic pressure P3 of the liquid container 39 is kept in equilibrium with the atmospheric pressure P2 in the second chamber 14 through the flexible film. Further, the liquid container 39 is installed in the second chamber 14 so that the liquid level on the upper surface 40 is lower than the nozzle opening surface 118 of the ejection head 116 by h.
In this configuration, the back pressure P4 at the meniscus 10 is given by equation (3).
P4 = P3-hρg = P2-hρg = P1-hρg (3)
As shown in the equation (3), the back pressure P4 is controlled by the control of the atmospheric pressure P1, and the back pressure P4 always maintains a state lower by hρg than the atmospheric pressure P1 regardless of its absolute value. That is, in the second embodiment, the atmospheric pressure control means for the atmospheric pressure P1 and the back pressure control means for the back pressure P4 are shared, and the control of the atmospheric pressure P1 and the back pressure P4 is unified. It is simple and pressure control can be easily performed.

In the maintenance unit 80 of the main body 101, a tube pump 41 as a suction unit is provided in the middle of the waste liquid tube 84 so that air or a liquid material in the cap member 87 can be sucked. The tube pump 41 is also connected to the pressure control device 23 and can control its driving.
In a state where the cap member 87 is brought into close contact with the nozzle opening surface 118 and the space 92 facing the nozzle opening surface 118 is sealed (see FIG. 4) (see FIG. 4), the state of the meniscus 10 is the pressure P1 in the first chamber 13. Instead, it depends on the pressure P5 in the cap member 87. In this state, when the tube pump 41 is driven, the atmospheric pressure P5 is reduced with respect to the atmospheric pressure P1 in the first chamber 13, and when the atmospheric pressure P5 is sufficiently lower than the back pressure P4, the liquid material in the liquid material flow path 12 is obtained. 11 is discharged from the nozzle 117.
That is, the maintenance unit 80 according to the second embodiment has a configuration in which the cap member 87 decompresses the inside of the small-capacity space 92 (see FIG. 4) facing the nozzle opening surface 118 and sucks the liquid material. ing. Therefore, compared to the first embodiment (FIG. 5) in which the liquid material 11 is discharged by controlling the atmospheric pressure of the large-capacity first chamber 13 or the second chamber 14, the discharge amount and discharge speed of the liquid material are controlled more sensitively. Is possible. Thus, it is possible to reduce the liquid discharge amount (waste liquid amount) required to discharge the bubbles.

FIG. 11 is a diagram illustrating the process of the recovery operation in the second embodiment, where the solid line indicates the change in the atmospheric pressure P1, the broken line indicates the change in the back pressure P4, and the dotted line indicates the change in the atmospheric pressure P5. Hereinafter, the recovery operation in the second embodiment will be described along the time axis of FIG. 11 with reference to FIG. In FIG. 11, the change in the atmospheric pressure P5 is shown only in the sections of step S32 and step S34.
In the initial state (step S30 in FIG. 11), the atmospheric pressure P1 in the first chamber 13 is set to atmospheric pressure, and the back pressure P4 at the position of the meniscus 10 is a value lower by hρg than the atmospheric pressure P1. Yes. As derived from the equation (3), the pressure difference between the atmospheric pressure P1 and the back pressure P4 = hρg is always maintained in the subsequent pressure control.

When the recovery operation is started, the atmospheric pressure P1 is lowered to PSL2 (step S31 in FIG. 11). This process corresponds to a static bubble control step, and the bubbles in the liquid channel 12 expand.
After the static bubble control step S31, the cap member 87 is brought into close contact with the nozzle opening surface 118 of the ejection head 116, and the tube pump 41 is driven. Then, the pressure P5 in the cap member 87 falls below the back pressure P4 to PSC1 as shown in FIG. 11 (step S32 in FIG. 11). At this time, due to the pressure difference between the atmospheric pressure P5 and the back pressure P4, the liquid material 11 is discharged from the nozzle 117 into the cap member 87, and the discharged liquid material 11 is stored in the waste liquid tank 90 through the waste liquid tube 84. Is done. This process corresponds to a dynamic bubble control step, and the bubbles remaining in the liquid material flow path 12 are discharged together with the discharge of the liquid material 11.
When the driving of the tube pump 41 is stopped after a predetermined time, the atmospheric pressure P5 rises and eventually reaches the same PSL2 as the atmospheric pressure P1. Then, the cap member 87 is separated from the nozzle opening surface 118.

  After step S32, a series of recovery is performed through static bubble control step S33, dynamic bubble control step S34, step S35 in the process of returning the pressure P1 to atmospheric pressure, and step S36 in which the nozzle opening surface 118 is wiped by the wiping means. The operation ends.

(Third embodiment)
FIG. 12 is a schematic configuration diagram illustrating the overall configuration of the droplet discharge device according to the third embodiment. Hereinafter, the description of the same portions as those in the first embodiment (FIG. 5) and the second embodiment (FIG. 10) will be omitted, and the third embodiment will be described focusing on the differences.

In the droplet discharge device 1 of FIG. 12, the main body 101 and the liquid supply unit 104 are installed in the atmosphere. The liquid material container 39 of the liquid material supply unit 104 is a container formed of a flexible film as in the second embodiment.
The droplet discharge device 1 includes a pressurizing device 59 as a back pressure control means. The pressurizing device 59 includes a drive unit 57, an arm unit 56 that is connected to the drive unit 57 and can be moved in the vertical direction in the drawing, a spring 55 provided on one end side of the arm unit 56, and the liquid container 39. A pressing plate 54 that contacts the upper surface 40 and presses the liquid container 39 via a spring 55 is provided. The drive unit 57 is connected to the pressure control device 23 and can control the amount of movement of the arm unit 56. With this configuration, a pressing force (pressure) P <b> 6 is generated at the contact surface between the pressing plate 54 and the upper surface 40, and the hydraulic pressure P <b> 3 in the liquid container 39 can be changed by the amount of movement of the arm portion 56.
The liquid container 39 is installed such that the liquid level on the upper surface 40 is lower than the nozzle opening surface 118 of the ejection head 116 by k, where k is a liquid level difference in the second embodiment = h. It is a sufficiently large value. The back pressure P4 at the meniscus 10 at this time is given by the following equation (4).
P4 = P3-kρg (4)
Although the hydraulic pressure P3 cannot be made lower than the atmospheric pressure, it is possible to control the back pressure P4 even in a range smaller than the atmospheric pressure by giving a negative position head component = −kρg initially. It is.

  Like this 3rd Embodiment, the back pressure control means in this invention is not limited to the aspect via air using the airtight container (chamber). As another aspect of the back pressure control means, a configuration in which the liquid level of the liquid container 39 can be changed to change the position head component is also conceivable.

In the droplet discharge device 1 of FIG. 12, the waste liquid tube 84 of the maintenance unit 80 is communicated with the waste liquid chamber 53. The waste liquid chamber 53 is an airtight container and communicates with the high-pressure tank 17 and the vacuum tank 18 through the vent pipe 51a and the vent pipe 51b and the vent pipe 51c branched from the vent pipe 51a, respectively. Further, the vent pipe 51b is provided with an open / close valve 50b, and the vent pipe 51c is provided with an open / close valve 50c. An atmospheric pressure sensor 52 is provided inside the waste liquid chamber 53. The atmospheric pressure sensor 52, the opening / closing valve 50b, and the opening / closing valve 50c are connected to the pressure control device 23, and the opening / closing control of the opening / closing valve 50b and the opening / closing valve 50c can be performed with reference to the detection value of the atmospheric pressure sensor 52.
When the cap member 87 is away from the nozzle opening surface 118, the pressure P5 in the cap member is equal to the atmospheric pressure. On the other hand, when the cap member 87 is brought into close contact with the nozzle opening surface 118 and the space 92 facing the nozzle opening surface 118 is sealed (see FIG. 4), the opening / closing control of the opening / closing valves 50b and 50c described above is performed. The pressure P5 can be freely controlled. In such a state, the atmospheric pressure P5 is the atmospheric pressure facing the opening of the nozzle 117. That is, the above-described configuration including the high pressure tank 17, the vacuum tank 18, the atmospheric pressure sensor 52, the cap member 87, the waste liquid tube 84, the waste liquid chamber 53, the opening / closing valve 50b, the opening / closing valve 50c, and the pressure control device 23 is It has become.

  Like this 3rd Embodiment, the atmospheric | air pressure control means in this invention is not limited to the aspect which accommodated the main-body part 101 in the airtight container (chamber) at least in the range of recovery operation | movement.

  The present invention is not limited to the above-described embodiment. For example, in the static bubble control step of the recovery operation, it is possible to adopt a configuration that can only perform an operation to make the pressure higher than the atmospheric pressure (no vacuum chamber), or conversely, a configuration that only allows the operation to make the pressure lower than the atmospheric pressure ( There may be no high pressure tank). Further, only a recovery operation may be possible, or only a drawing operation may be possible. Moreover, each structure of each embodiment can combine these suitably, can be abbreviate | omitted, or can combine with the other structure which is not shown in figure.

The schematic perspective view which shows the principal part structure of a droplet discharge apparatus. FIG. 3 is a plan view showing an arrangement of ejection heads in a head unit. FIG. 2 is a schematic perspective view showing a main part structure of a discharge head. The schematic sectional drawing which shows a part of maintenance unit. The schematic block diagram which shows the whole structure of a droplet discharge apparatus. The schematic sectional drawing which shows the state of the bubble in a liquid body flow path. The schematic sectional drawing which shows the state of the bubble in a liquid body flow path. The figure which shows the change of the atmospheric | air pressure in a 1st chamber, and the back pressure in a liquid material flow path in recovery operation | movement. The figure which shows the change of the atmospheric | air pressure in a 1st chamber, and the back pressure in a liquid material flow path in drawing operation | movement. The schematic block diagram which shows the whole structure of the droplet discharge apparatus in 2nd Embodiment. The figure which shows the process of the recovery operation | movement in 2nd Embodiment. The schematic block diagram which shows the whole structure of the droplet discharge apparatus in 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Droplet discharge apparatus, 10 ... Meniscus, 11 ... Liquid body, 12 ... Liquid body flow path, 13 ... 1st chamber which comprises an airtight container and atmospheric pressure control means, 14 ... 2nd chamber which comprises back pressure control means , 15... Compressor, 16... Vacuum pump, 17... High pressure tank constituting atmospheric pressure control means and back pressure control means, 18... Vacuum tank constituting atmospheric pressure control means and back pressure control means, 19, 20. Barometric pressure sensors constituting back pressure control means, 21a to 21f ... vent pipes constituting barometric pressure control means and back pressure control means, 22a to 22d ... Opening / closing valves constituting barometric pressure control means and back pressure control means, 23 ... barometric pressure control Pressure control device constituting the means and back pressure control means, 24... Outlet, 25 .. atmosphere communication port, 28... Liquid level, 29 .. waste liquid, 30. , 35... Air bubbles, 36a to 36c... Ventilation pipe constituting the atmospheric pressure control means and back pressure control means, 37... Air pressure sensor constituting the atmospheric pressure control means and back pressure control means, 38a and 38b. Open / close valve constituting means, 39 ... liquid container, 40 ... upper surface, 41 ... tube pump as suction means, 42 ... outlet, 50b, 50c ... open / close valve constituting atmospheric pressure control means, 51a to 51c ... atmospheric pressure control Ventilation pipe constituting means, 52 ... atmospheric pressure sensor constituting atmospheric pressure control means, 53 ... waste liquid chamber constituting atmospheric pressure control means, 54 ... pressing plate, 55 ... spring, 56 ... arm part, 57 ... drive part, 59 ... Pressure device as back pressure control means, 80 ... maintenance section, 81 ... cap unit, 83 ... unit base, 84 ... waste liquid tube, 85, 89 ... cap gas 86 ... Spring 87 ... Cap member 88 ... Receiver 90 ... Waste liquid tank 92 ... Space 101 ... Main body part 102 ... Head mechanism part 103 ... Substrate mechanism part 104 ... Liquid material supply part 110 DESCRIPTION OF SYMBOLS ... Head part, 116 ... Discharge head, 117 ... Nozzle, 118 ... Nozzle opening surface, 120 ... Substrate, 130a-130c ... Liquid container, 131a-131c ... Supply tube, 140 ... Cavity, 141 ... Septum, 142 ... Vibrator 143, vibration plate, 144, nozzle plate, 145, reservoir, 146, supply port, 147, hole, 150, droplet.

Claims (4)

A method for discharging bubbles in a liquid channel that communicates a liquid container with a discharge head in which a nozzle of a droplet discharge device is formed,
While maintaining the pressure difference between the atmospheric pressure facing the nozzle opening surface and the back pressure in the liquid channel, the meniscus formed in the nozzle opening can maintain a non-flowing state,
A high-pressure static bubble control step for bringing the atmospheric pressure to a state higher than atmospheric pressure;
And a dynamic bubble control step of generating a pressure difference between the atmospheric pressure and the back pressure and discharging the liquid material in the liquid material flow path from the nozzle. . After the high-pressure static bubble control step, a first discharge step of discharging the liquid material in the liquid material channel from the nozzle in the dynamic bubble control step;
While maintaining the pressure difference that the atmospheric pressure and the back pressure can maintain a non-flow state meniscus formed in the opening of the nozzle ,
A second discharge step of discharging the liquid material in the liquid channel from the nozzle in the dynamic bubble control step after the low pressure static bubble control step of setting the atmospheric pressure to a state lower than the atmospheric pressure; The bubble discharging method according to claim 1, comprising: The method for discharging bubbles according to claim 2 , wherein the plurality of first discharging steps and the plurality of second discharging steps are executed in combination. One end side of the liquid material channel formed in the discharge head communicates with the liquid material container, and the other end of the liquid material channel serves as a nozzle, and the supply of the liquid material from the liquid material container receives the nozzle. A droplet discharge method in a droplet ejecting apparatus that discharges droplets from
While maintaining the pressure difference between the atmospheric pressure facing the nozzle opening surface and the back pressure in the liquid channel, the meniscus formed in the nozzle opening can maintain a non-flowing state,
A high-pressure static bubble control step for bringing the atmospheric pressure to a state higher than atmospheric pressure;
A droplet discharge method comprising: a discharge step of discharging the droplet from the nozzle after the high-pressure static bubble control step.

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