Droplet ejection device, and method for manufacturing printed matter

Abstract

The present invention provides: a droplet ejection device, which maintains good ejection performance even if a low-density gas is used; and a method for manufacturing printed matter. This droplet ejection device comprises: a droplet ejection head for ejecting a liquid; a relative moving mechanism for moving the droplet ejection head and a substrate relative to one another; and a control device that prints an image on the substrate by causing the droplet ejection head and the substrate to move relative to one another and causing the droplet ejection head to eject droplets. A low-density gas having a lower density than air is provided between the droplet ejection head and the substrate. The droplet ejection head comprises a circulation flow path along which the liquid circulates. The control device causes the liquid to circulate, at least during printing.

Description

Droplet ejection device and method for manufacturing printed matter

[0001] The present invention relates to a droplet ejection device and a method for producing a printed matter, and more particularly to a technique for stabilizing the ejection state.

[0002] As inkjet droplets become smaller (for example, 3 pL or less per droplet), they are more susceptible to the air resistance between the inkjet head and the substrate. As a result, when the distance between the inkjet head and the substrate is large, the droplets may not land on the substrate, or even if they do land, they may not land in the correct location due to external disturbances such as wind.

[0003] As a technique for reducing the air resistance between the inkjet head and the substrate, Patent Documents 1 and 2 describe replacing the air in the printing section with helium.

[0004] Japanese Patent No. 7068846 Japanese Patent Application Laid-Open No. 2018-12343

[0005] However, the techniques described in Patent Documents 1 and 2 have the problem that the solvent component in the ink evaporates, deteriorating the ejection state.

[0006] The present invention has been made in view of the above circumstances, and has as its object to provide a droplet ejection device that maintains a good ejection state even in a low-density gas environment, and a method for producing a printed matter.

[0007] To achieve the above object, a droplet ejection device according to a first aspect of the present disclosure includes a droplet ejection head that ejects liquid, a relative movement mechanism that moves a substrate and the droplet ejection head relative to each other, and a control device that prints an image on the substrate by moving the substrate and the droplet ejection head relative to each other and ejecting liquid from the droplet ejection head, wherein a low-density gas having a density lower than that of air is contained between the droplet ejection head and the substrate, the droplet ejection head has a circulation flow path therein, and the control device circulates the liquid through the circulation flow path at least during printing. According to this aspect, a good ejection state can be maintained.

[0008] A droplet ejection device according to a second aspect of the present disclosure is a droplet ejection device according to the first aspect, wherein the droplet ejection head has an ejection element including a nozzle, a pressure chamber, and an ejection energy generating element, and the circulation flow path preferably includes a supply flow path that supplies liquid to the ejection element and a recovery flow path that recovers liquid from the ejection element.

[0009] A droplet ejection device according to a third aspect of the present disclosure is a droplet ejection device according to the first or second aspect, wherein the control device preferably makes the amount of liquid circulated during printing greater than the amount of liquid circulated during non-printing.

[0010] A droplet ejection device according to a fourth aspect of the present disclosure is the droplet ejection device according to any one of the first to third aspects, wherein the control device preferably stops circulation of the liquid when printing is not being performed.

[0011] A droplet ejection device according to a fifth aspect of the present disclosure is a droplet ejection device according to any one of the first to fourth aspects, wherein the control device preferably applies vibration to non-ejecting nozzles during printing to an extent that droplets are not ejected.

[0012] A droplet ejection device according to a sixth aspect of the present disclosure is a droplet ejection device according to any one of the first to fifth aspects, which is provided with a supply mechanism that supplies low-density gas between the droplet ejection head and the substrate, and it is preferable that the supply mechanism stops supplying the low-density gas during printing.

[0013] A droplet ejection device according to a seventh aspect of the present disclosure is a droplet ejection device according to any one of the first to sixth aspects, which comprises a chamber that houses a droplet ejection head and a relative movement mechanism therein, and the chamber preferably has an inlet slit through which the substrate is transported and an outlet slit through which the substrate is transported, and the inlet slit and the outlet slit each preferably have a shutter that can be opened and closed.

[0014] A droplet ejection device according to an eighth aspect of the present disclosure is the droplet ejection device according to the seventh aspect, wherein the liquid preferably contains a solvent, and the solvent is disposed in an open state inside the chamber.

[0015] A droplet ejection device according to a ninth aspect of the present disclosure is a droplet ejection device according to any one of the first to sixth aspects, wherein the liquid contains a solvent, and the supply mechanism preferably supplies a low-density gas containing a solvent vapor.

[0016] A droplet ejection device according to a tenth aspect of the present disclosure is the droplet ejection device according to any one of the first to ninth aspects, wherein the liquid is preferably an aqueous ink containing water as a solvent.

[0017] To achieve the above object, a method for producing a printed matter according to an eleventh aspect of the present disclosure is a method for producing a printed matter, which includes supplying a low-density gas having a density lower than that of air between a droplet ejection head and a substrate, printing an image on the substrate by ejecting liquid from the droplet ejection head while moving the substrate and the droplet ejection head relative to each other, and circulating the liquid through a circulation flow path of the droplet ejection head at least during printing. According to this aspect, a good ejection state can be maintained.

[0018] According to the present invention, a good ejection state can be maintained even in a low-density gas environment.

[0019] FIG. 1 is a side view showing an outline of a printing apparatus. FIG. 2 is a plan view showing an outline of a printing apparatus. FIG. 3 is a perspective view of a droplet ejection head. FIG. 4 is a plan perspective view showing an example of the structure of a silicon die. FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4. FIG. 6 is a cross-sectional view taken along line 5-5 of FIG. 4 according to a modified example. FIG. 7 is a schematic view showing an example of the configuration of a printing apparatus according to a second embodiment. FIG. 8 is a schematic view showing an example of the configuration of a printing apparatus according to a third embodiment. FIG. 9 is a schematic view showing an example of the configuration of a printing apparatus according to a fourth embodiment. FIG. 10 is a schematic view showing an example of the configuration of a printing apparatus according to a fifth embodiment. FIG. 11 is a schematic view showing an example of the configuration of a printing apparatus according to a sixth embodiment. FIG. 12 is a block diagram showing the electrical configuration of a printing apparatus.

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the description of each embodiment, illustration and description of parts common to other embodiments will be omitted as appropriate.

[0021] <Outline of Printing Apparatus: First Embodiment> Fig. 1 is a side view showing an outline of a printing apparatus 10, and Fig. 2 is a plan view showing an outline of the printing apparatus 10. The printing apparatus 10 is a droplet ejection device that prints an image on a substrate 1.

[0022] The printing device 10 includes a transport device 12, a droplet ejection head 14, and a helium supply mechanism 15. The transport device 12 is a relative movement mechanism that moves the substrate 1 relative to the droplet ejection head 14 by transporting the substrate 1 in the horizontal Y direction. The droplet ejection head 14 is an inkjet head that ejects droplets I of aqueous ink (an example of a "liquid") containing water as a solvent using an inkjet method.

[0023] The printing device 10 forms an image by ejecting ink droplets I from a droplet ejection head 14 onto a recording surface of a substrate 1 transported in the Y direction by a transport device 12. The substrate 1 is, for example, a printed circuit board, and the ink is, for example, a conductive ink containing a conductive material. The printing device 10 may also include a head carriage that moves the droplet ejection head 14 in the X direction.

[0024] The helium supply mechanism 15 includes a helium tank (not shown) that stores helium gas (hereinafter referred to as helium), which is an example of a low-density gas having a density lower than that of air. The helium supply mechanism 15 supplies helium from the helium tank to at least the space S between the droplet discharge head 14 and the substrate 1. As a result, helium is mainly contained in the space S. Of the gas present in the space S, it is preferable that 50% or more is low-density gas, more preferably 90% or more is low-density gas, and even more preferably 99% or more is low-density gas.

[0025] In this way, by changing the gas in the space S from air, which is mainly composed of nitrogen, to a low-density gas containing hydrogen and / or helium, the density ρ of the gas can be reduced and the Reynolds number Re can be made smaller. The smaller the Reynolds number Re, the laminar flow becomes, and at least the pressure resistance caused by separation can be reduced.

[0026] This reduces the air resistance of the droplets I, so that the printing device 10 can maintain a good ejection state and accurately land the droplets I on the substrate 1 even when the distance between the droplet ejection head 14 and the substrate 1 is relatively wide, such as 5 mm to 30 mm. In a typical printing device, the distance between the droplet ejection head and the substrate to accurately land the droplets I is about 0.5 mm to 2 mm.

[0027] Note that the printing device 10 stops the inflow (supply) of helium from the helium supply mechanism 15 when ink is being ejected from the droplet ejection head 14. This makes it possible to suppress ejection disturbances caused by gas flow. This is because ejection using the inkjet method is very sensitive to gas flow and is easily affected by it, causing the ejection direction of the droplets I to bend. The printing device 10 may supply helium from the helium supply mechanism 15 in an amount that does not affect the droplets I due to the helium flow.

[0028] The supply of helium from the helium supply mechanism 15 may be stopped during printing. The period during printing includes at least a state in which the droplet ejection head 14 and the substrate 1 face each other. The printing device 10 prints by applying ink using the droplet ejection head 14 while the substrate 1 is transported by the transport device 12. In this embodiment, the period during which the substrate 1 is printing is from when it reaches a position facing the droplet ejection head 14 until it has completely passed the position facing the droplet ejection head 14, and the remaining periods are non-printing periods.

[0029] [Configuration of droplet ejection head] When the air in the space S is replaced with helium, there is a concern that the ink solvent may evaporate, resulting in a deterioration in ejection. In this embodiment, a droplet ejection head that circulates ink to the periphery of the nozzles is used to stabilize the ejection state even if the ink solvent evaporates.

[0030] 3 is a perspective view of the droplet ejection head 14. The droplet ejection head 14 includes an L-shaped bracket 16, a silicon die 24, an ink supply path 18, an ink recovery path 20, and a filter housing 22.

[0031] The L-shaped bracket 16 is a member for fixing the droplet ejection head 14 to a head support member (not shown).

[0032] The ink supply path 18 is connected to an upper ink tank 32 (see FIG. 8). The ink supply path 18 supplies ink from the upper ink tank 32 to the droplet ejection head 14. The ink recovery path 20 is connected to a lower ink tank 34 (see FIG. 8). The ink recovery path 20 recovers the ink supplied to the droplet ejection head 14 into the lower ink tank 34.

[0033] The filter housing 22 houses a filter for removing foreign matter and the like contained in the ink inside the droplet ejection head 14 .

[0034] The silicon die 24 has a nozzle surface 200 (see FIG. 5) that faces the substrate 1 transported by the transport device 12. Fig. 4 is a plan perspective view showing an example of the structure of the silicon die 24, and Fig. 5 is a cross-sectional view taken along line 5-5 in Fig. 4.

[0035] The silicon die 24 includes a nozzle plate 230 in which nozzles 202, which are ink droplet ejection ports, are formed, and a flow path plate 232 in which ink flow paths are formed. The nozzle plate 230 and the flow path plate 232 are laminated and bonded together. The flow path plate 232 has a structure in which one or more substrates are laminated. The nozzle plate 230 and the flow path plate 232 are made of silicon and can be processed into the required shape using a semiconductor manufacturing process.

[0036] The silicon die 24 has a plurality of nozzles 202 on its bottom surface, the nozzle surface 200. A plurality of ink chamber units 206, each consisting of a pressure chamber 204 and the like provided corresponding to each nozzle 202, are arranged two-dimensionally in a fixed array pattern. This achieves a high density of the effective nozzle spacing projected as being aligned along the X direction.

[0037] The pressure chambers 204 are connected to supply tributaries 210 via supply restrictors 208, and each supply tributary 210 is connected to a common flow path 212. In addition, a descender 214 connected to each pressure chamber 204 is connected to an ink circulation path 216 and a common circulation path 220 via a recovery tributary 218. The silicon die 24 is provided with an ink supply port 18A and an ink discharge port 20A. The ink supply path 18 (see FIG. 3) is connected to the ink supply port 18A. The ink discharge port 20A is connected to the ink recovery path 20 (see FIG. 3).

[0038] In this way, the ink supply port 18A and ink discharge port 20A of the silicon die 24 are connected via the common flow path 212, the supply tributary 210, the supply restrictor 208, the pressure chamber 204, the descender 214, the ink circulation path 216, the recovery tributary 218, and the circulation common flow path 220.

[0039] Therefore, the ink supplied from the ink supply path 18 to the ink supply port 18A flows through the common flow path 212, the supply tributary 210, the supply restrictor 208, the pressure chamber 204, and the descender 214, and a portion of the ink is ejected from each nozzle 202, while the remaining ink is discharged from the ink discharge port 20A to the ink recovery path 20 via the ink circulation path 216, the recovery tributary 218, and the circulation common flow path 220.

[0040] Furthermore, a piezoelectric actuator 228 equipped with an individual electrode (not shown) is joined to a vibration plate 226 that forms the top surface of the pressure chamber 204 and also serves as a common electrode. When a predetermined voltage is applied to the individual electrode, the piezoelectric actuator 228 deforms in a direction that contracts the pressure chamber 204. This causes ink to be ejected from the nozzle 202. The piezoelectric actuator 228 then deforms in a direction that expands the pressure chamber 204. This causes new ink to be supplied to the pressure chamber 204 from the common flow path 212 through the supply tributary 210 and the supply orifice 208.

[0041] Here, a piezo actuator 228 is used as the ejection energy generating element for ejecting ink from the nozzle 202, but it is also possible to apply a thermal method in which a heater is provided inside the pressure chamber 204 and ink is ejected using the pressure of film boiling caused by heating by the heater.

[0042] As such, the droplet ejection head 14 has an ejection element 222 that includes a nozzle 202, a pressure chamber 204, and a piezoelectric actuator 228. The droplet ejection head 14 also includes a supply tributary 210 (an example of a "supply flow path") that supplies ink to the ejection element 222, and a recovery tributary 218 (an example of a "recovery flow path") that recovers ink from the ejection element 222. The supply tributary 210 and the recovery tributary 218 together form a "circulation flow path."

[0043] The ink circulation path 216 is preferably configured to be provided around the nozzle 202. Here, the ink circulation path 216 is provided in a region that communicates with the descender 214 and is in contact with the nozzle plate 230 of the flow path plate 232. This allows the ink to circulate near the nozzle 202, preventing the ink inside the nozzle 202 from thickening and enabling stable ejection.

[0044] Figure 6 is a cross-sectional view of a modified example taken along line 5-5 of Figure 4. In the modified example shown in Figure 6, the ink circulation path 216 is provided in an area that communicates with the descender 214 and is in contact with the vibration plate 226. Even with this configuration, the effect is less than that of the ink chamber unit 206 shown in Figure 5, but ink circulates near the nozzle 202, enabling stable ejection.

[0045] As described above, by using a droplet ejection head 14 in which ink is circulated, new ink is continuously supplied to the ink chamber unit 206, even when the ink solvent evaporates from the nozzles 202 in an environment where the partial pressure of the ink's main solvent is low. This makes it possible to maintain a stable ejection state even in a helium environment where the partial pressure of the solvent is 0 atmospheres. In particular, because water has a high vapor pressure and is prone to evaporation, water-based inks are difficult to use in printing devices that use helium, but ink circulation makes it possible to use water-based inks. Furthermore, to address the lack of heat dissipation in the droplet ejection head 14, ink circulation allows the heat generated by the droplet ejection head 14 to be extracted to the outside through the ink.

[0046] It is desirable to change the ink circulation volume when the printing device 10 is printing and when it is not printing. When printing, it is desirable to have fresh ink always flowing into the ink chamber unit 206, so the ink circulation volume should be increased as much as possible. When printing, the ink circulation volume is typically 1,000 pL / sec to 10,000 pL / sec per nozzle. For the same ink, it is desirable to circulate the ink at a volume at least twice as large, more preferably at least three times as large, and even more preferably at least five times as large.

[0047] On the other hand, since ink evaporation should be minimized when not printing, it is desirable to reduce the amount of ink circulated compared to when printing, to a level that prevents the nozzle 202 from solidifying due to ink evaporation. For example, since clogging of the nozzle 202 does not occur for several minutes even in a helium environment with aqueous ink, in this case, stopping ink circulation for only a short time can also be selected as a method for suppressing solvent evaporation. In other words, when not printing, the cycle of stopping circulation → a few minutes later → circulation → a few minutes later → stopping circulation... can be repeated. In this way, by stopping ink circulation at unnecessary times or reducing the amount of ink circulation, unnecessary ink evaporation can be reduced.

[0048] Furthermore, in order to suppress the adverse effects of ink solvent evaporation on ejection, it is desirable to apply vibrations (so-called meniscus shaking) from the piezo actuator 228 to non-ejecting nozzles that do not eject ink during printing, to the extent that they do not eject ink. By combining this with ink circulation, fresh ink can be sent to the nozzles 202, which further suppresses an increase in ink viscosity in the nozzles 202 and achieves more stable ejection.

[0049] 7 is a schematic diagram showing an example of the configuration of a printing apparatus 10A according to a second embodiment. The printing apparatus 10A includes a chamber 30 and an exhaust mechanism 31.

[0050] The chamber 30 accommodates the transport device 12 (not shown in FIG. 7) and the droplet ejection head 14 .

[0051] The chamber 30 also has an exhaust port and a helium supply port (not shown). The exhaust port is connected to an exhaust mechanism 31, and the helium supply port is connected to a helium supply mechanism 15. The exhaust mechanism 31 exhausts air from the interior of the chamber 30 through the exhaust port, creating a low vacuum (0.1 atmospheres or less) that is relatively lower than atmospheric pressure. The helium supply mechanism 15 supplies helium into the interior of the chamber 30 through the helium supply port, creating a helium atmosphere inside the chamber 30 at a pressure equal to atmospheric pressure (1 atmosphere). This replaces the air inside the chamber 30 with helium.

[0052] The configuration of the printing device 10A makes it easier to control the flow of helium. Note that when replacing the gas inside the chamber 30 with helium, care must be taken to prevent ink from being sprayed out of the nozzles 202 of the droplet ejection head 14 when the exhaust mechanism 31 exhausts the air inside the chamber 30 to create a low vacuum.

[0053] <Ink Tank Arrangement: Third Embodiment> The ink tank that stores ink to be circulated to the droplet ejection head 14 may be located inside the chamber 30 filled with helium, or may be located outside the chamber 30. Here, a case where the ink tank is located inside the chamber 30 will be described.

[0054] 8 is a schematic diagram showing an example of the configuration of a printing device 10B according to the third embodiment. The printing device 10B includes an upper ink tank 32, a lower ink tank 34, a return flow path 36, and an ink pump 38 inside a chamber 30.

[0055] The upper ink tank 32 is a container for storing ink to be supplied to the droplet ejection head 14. The upper ink tank 32 is in communication with the droplet ejection head 14 via the ink supply path 18. The interior of the upper ink tank 32 is open to the atmosphere inside the chamber 30. The upper ink tank 32 is supported by a first up-and-down movement mechanism 72 (see FIG. 12) that is movable in the vertical direction (Z direction), and is positioned at a height that provides the desired head difference.

[0056] The lower ink tank 34 is a container for storing ink recovered from the droplet ejection head 14. The lower ink tank 34 is in communication with the droplet ejection head 14 via the ink recovery path 20. The interior of the lower ink tank 34 is open to the atmosphere inside the chamber 30. The lower ink tank 34 is supported by a second up-and-down movement mechanism 74 (see FIG. 12) that is movable in the vertical direction, and is positioned at a height that provides the desired head difference.

[0057] The return flow path 36 connects the upper ink tank 32 and the lower ink tank 34. An ink pump 38, which is a liquid delivery mechanism, is provided in the return flow path 36 and delivers ink from the lower ink tank 34 to the upper ink tank 32.

[0058] In this way, the printing device 10B has the droplet ejection head 14 disposed between the upper ink tank 32 and the lower ink tank 34. The upper ink tank 32 and the lower ink tank 34 have a mechanism for causing ink to flow to the droplet ejection head 14 by a head difference using gravity with the pressure inside the chamber 30 as the reference. This results in a simple ink circulation configuration.

[0059] The amount of circulated ink can be controlled by the first vertical movement mechanism 72 and the second vertical movement mechanism 74. To minimize the effect on ejection, it is desirable to move the upper ink tank 32 and the lower ink tank 34 up and down when ink is not being ejected from the droplet ejection head 14.

[0060] In the printing device 10B, when the air inside the chamber 30 is evacuated to create a low vacuum, ink spurts out from the open areas of the upper ink tank 32 and the lower ink tank 34. Ink also spurts out from the nozzles 202 of the droplet ejection head 14. For this reason, before evacuating the air, it is necessary to close the valves (not shown) connected to the droplet ejection head 14 and also to close the valves (not shown) at the open parts of the upper ink tank 32 and the lower ink tank 34. These valves can be opened again after helium is supplied into the chamber 30.

[0061] In a low vacuum state, pressure is applied to the ink supply path 18, the ink recovery path 20, the tubes of the return flow path 36, the upper ink tank 32, and the lower ink tank 34 to expand them, so it is desirable not to use materials that stretch easily, such as rubber or soft tubes.

[0062] <Prevention of Solvent Evaporation: Fourth Embodiment> In order to prevent evaporation of the ink solvent from the liquid surface of the upper ink tank 32 and the lower ink tank 34, a film or beads may be floated on the liquid surface to reduce the exposed surface area.

[0063] Furthermore, the upper ink tank 32 and the lower ink tank 34 may be closed with a soft material such as a damper membrane that can follow changes in external pressure, rather than being open to the atmosphere inside the chamber 30. The upper ink tank 32 and the lower ink tank 34 may be configured as a pouch or other material that can be deformed as a whole.

[0064] Furthermore, to prevent solvent evaporation from the nozzles 202 of the droplet ejection head 14, only the solvent may be added to the chamber 30 in advance. FIG. 9 is a schematic diagram showing an example configuration of a printing apparatus 10C according to a fourth embodiment. The printing apparatus 10C includes a container 50 inside the chamber 30. The container 50 is positioned vertically below the droplet ejection head 14. The container 50 contains the ink solvent (water in this case), and the solvent is open to the space inside the chamber 30. Therefore, the solvent inside the container 50 evaporates naturally. This increases the partial pressure of the solvent, preventing ink evaporation from the nozzles 202. While this naturally affects air resistance, this is not a problem because gases other than the main solvent are unlikely to be generated.

[0065] The helium supply mechanism 15 may supply helium containing a gas that is the main solvent of the ink to the inside of the chamber 30. Alternatively, a mechanism for supplying a gas that is the main solvent of the ink may be provided separately from the helium supply mechanism 15. In these cases, the container 50 is not required, so the printing device 10C can be made compact, and evaporation of the ink solvent from the nozzles 202 can be prevented.

[0066] Since the air collected through the exhaust mechanism 31 contains helium, it is desirable to separate the helium from the collected air and reuse the separated helium.

[0067] <Loading and Unloading of Substrate: Fifth Embodiment> In order to minimize the loss of helium when loading and unloading the substrate 1, it is desirable to load and unload the substrate 1 through a relatively narrow slit that can be opened and closed. Figure 10 is a schematic diagram showing an example configuration of a printing device 10D according to the fifth embodiment. The chamber 30 of the printing device 10D includes an inlet slit 60A, an outlet slit 60B, and an inlet shutter 62A and an outlet shutter 62B that can be opened and closed, respectively.

[0068] The loading slit 60A is a slit-shaped opening for loading the substrate 1 from the outside to the inside of the chamber 30. The unloading slit 60B is a slit-shaped opening for unloading the substrate 1 from the inside to the outside of the chamber 30.

[0069] The carry-in shutter 62A and the carry-out shutter 62B are each disposed on a transport path of the substrate 1 by the transport device 12. The carry-in shutter 62A is disposed in the carry-in slit 60A and opens and closes the carry-in slit 60A. The carry-out shutter 62B is disposed in the carry-out slit 60B and opens and closes the carry-out slit 60B.

[0070] When the substrate 1 outside the chamber 30 is to be transported into the chamber 30, the transport device 12 opens the transport shutter 62A, transports the substrate 1 into the chamber 30, and then closes the transport shutter 62A.

[0071] When the substrate 1 inside the chamber 30 is to be transported to the outside of the chamber 30, the transport shutter 62B is opened, the substrate 1 is transported to the outside of the chamber 30 by the transport device 12, and the transport shutter 62B is closed.

[0072] By transporting the substrate 1 in the above manner, it is possible to reduce the loss of helium when the substrate 1 is carried in and out.

[0073] 11 is a schematic diagram showing an example of the configuration of a printing apparatus 10E according to a sixth embodiment. The chamber 30 of the printing apparatus 10E includes a first shutter 64A, a second shutter 64B, a third shutter 64C, and a fourth shutter 64D, each of which can be opened and closed.

[0074] The first shutter 64A, the second shutter 64B, the third shutter 64C, and the fourth shutter 64D are each disposed on a transport path of the substrate 1 by the transport device 12. The first shutter 64A is disposed in the carry-in slit 60A and opens and closes the carry-in slit 60A. The fourth shutter 64D is disposed in the carry-out slit 60B and opens and closes the carry-out slit 60B.

[0075] The chamber 30 has a first adjustment chamber 66A between the first shutter 64A and the second shutter 64B, which is a space that is relatively narrower than the helium space inside the chamber 30 in which the droplet ejection head 14 and the like are disposed. The chamber 30 also has a second adjustment chamber 66B between the third shutter 64C and the fourth shutter 64D, which is a space that is relatively narrower than the helium space inside the chamber 30. The first adjustment chamber 66A and the second adjustment chamber 66B each include a vacuum pump (not shown).

[0076] The second shutter 64B switches between opening and closing the first adjustment chamber 66A and the helium space, and the third shutter 64C switches between opening and closing the helium space and the second adjustment chamber 66B.

[0077] When the substrate 1 outside the chamber 30 is transported into the chamber 30, the first shutter 64A is first opened, the substrate 1 is transported into the first adjustment chamber 66A by the transport device 12, and the first shutter 64A is closed. Next, the second shutter 64B is opened, the substrate 1 is transported into the helium space of the chamber 30 by the transport device 12, and the second shutter 64B is closed.

[0078] Furthermore, when the substrate 1 inside the chamber 30 is to be transported to the outside of the chamber 30, the third shutter 64C is opened, the substrate 1 is transported into the second adjustment chamber 66B by the transport device 12, and the third shutter 64C is closed. Next, the fourth shutter 64D is opened, the substrate 1 is transported to the outside of the chamber 30 by the transport device 12, and the fourth shutter 64D is closed.

[0079] By transporting the substrate 1 in the above manner, the substrate 1 can be carried into the helium space where the droplet discharge head 14 is located without introducing a large amount of air into the helium space.

[0080] 12 is a block diagram showing the electrical configuration of the printing devices 10, 10A, 10B, 10C, 10D, and 10E. The printing devices 10, 10A, 10B, 10C, 10D, and 10E each include a control device 70. The control device 70 includes a processor 70A and a memory 70B.

[0081] The processor 70A executes instructions stored in the memory 70B. The hardware configuration of the processor 70A is the following various processors. The various processors include a CPU (Central Processing Unit), which is a general-purpose processor that executes software (programs) and functions as various functional units, a GPU (Graphics Processing Unit), which is a processor specialized for image processing, a PLD (Programmable Logic Device), which is a processor whose circuit configuration can be changed after manufacture such as an FPGA (Field Programmable Gate Array), and a dedicated electrical circuit, such as an ASIC (Application Specific Integrated Circuit), which is a processor having a circuit configuration designed specifically for executing specific processing.

[0082] A single processing unit may be configured with one of these various processors, or may be configured with two or more processors of the same or different types (e.g., multiple FPGAs, a combination of a CPU and an FPGA, or a combination of a CPU and a GPU). Multiple functional units may also be configured with a single processor. Examples of multiple functional units configured with a single processor include: a first configuration, as typified by a client or server computer, in which a single processor is configured with a combination of one or more CPUs and software, and this processor operates as multiple functional units; and a second configuration, as typified by a SoC (System on Chip), in which a processor is used to realize the functions of an entire system including multiple functional units on a single IC (Integrated Circuit) chip. In this way, the various functional units are configured with one or more of the above-mentioned various processors as a hardware structure.

[0083] Furthermore, the hardware structure of these various processors is, more specifically, an electric circuit made up of a combination of circuit elements such as semiconductor elements.

[0084] The memory 70B stores instructions to be executed by the processor 70A. The memory 70B includes a random access memory (RAM) and a read-only memory (ROM). The processor 70A uses the RAM as a working area, executes software using various programs and parameters stored in the ROM, and executes various processes for controlling the printing devices 10, 10A, 10B, 10C, 10D, and 10E by using parameters stored in the ROM, etc.

[0085] The control device 70 controls the helium supply mechanism 15 and the exhaust mechanism 31. That is, the control device 70 reduces the pressure inside the chamber 30 using the exhaust mechanism 31, creating a low vacuum state of, for example, 0.1 atmospheres inside the chamber 30. The control device 70 also supplies helium to the space S between the droplet discharge head 14 and the substrate 1 using the helium supply mechanism 15. Furthermore, the control device 70 supplies helium using the helium supply mechanism 15 when printing is not being performed, and stops the supply of helium by the helium supply mechanism 15 when printing is being performed.

[0086] The control device 70 controls the droplet ejection head 14. That is, the control device 70 ejects ink droplets I from the nozzles 202 of the droplet ejection head 14 to form an image on the substrate 1. Furthermore, during printing, the control device 70 vibrates the meniscus of the non-ejecting nozzles 202 by applying vibrations to the piezoelectric actuators 228 of the non-ejecting nozzles 202 to an extent that does not eject ink.

[0087] The control device 70 controls the transport device 12, the carry-in shutter 62A, and the carry-out shutter 62B. That is, the control device 70 transports the substrate 1 in the Y direction using the transport device 12. Furthermore, when the substrate 1 is carried into the chamber 30, the control device 70 opens and closes the carry-in shutter 62A to prevent a large amount of air from entering the helium space inside the chamber 30. Furthermore, when the substrate 1 is carried out of the chamber 30, the control device 70 opens and closes the carry-out shutter 62B to prevent a large amount of air from entering the helium space inside the chamber 30.

[0088] The control device 70 controls the transport device 12, the first shutter 64A, the second shutter 64B, the third shutter 64C, and the fourth shutter 64D. That is, the control device 70 transports the substrate 1 in the Y direction using the transport device 12. Furthermore, when the substrate 1 is transported into the chamber 30, the control device 70 opens and closes the first shutter 64A and the second shutter 64B in sequence to prevent a large amount of air from entering the helium space inside the chamber 30. Furthermore, when the substrate 1 is transported out of the chamber 30, the control device 70 opens and closes the third shutter 64C and the fourth shutter 64D in sequence to prevent a large amount of air from entering the helium space inside the chamber 30.

[0089] The control device 70 controls the ink pump 38. That is, the control device 70 causes the ink pump 38 to pump ink from the lower ink tank 34 to the upper ink tank 32.

[0090] The control device 70 controls the first up-down movement mechanism 72 and the second up-down movement mechanism 74. That is, the control device 70 adjusts the vertical position of the upper ink tank 32 using the first up-down movement mechanism 72 to adjust the head difference between the upper ink tank 32 and the droplet ejection head 14, and adjusts the vertical position of the lower ink tank 34 using the second up-down movement mechanism 74 to adjust the head difference between the droplet ejection head 14 and the lower ink tank 34, thereby controlling the circulation of ink in the droplet ejection head 14.

[0091] The control device 70 makes the amount of ink circulated during printing by the droplet ejection head 14 greater than the amount of ink circulated during non-printing. The control device 70 stops the circulation of ink during non-printing.

[0092] The printing devices 10, 10A, 10B, 10C, 10D, and 10E configured as described above can implement a method for manufacturing a printed matter, which includes supplying helium to the space S between the droplet ejection head 14 and the substrate 1, circulating ink through the droplet ejection head 14, and printing on the substrate 1 by moving the substrate 1 and the droplet ejection head 14 relative to each other using the conveying device 12 and ejecting ink from the droplet ejection head 14.

[0093] According to the printing devices 10, 10A, 10B, 10C, 10D, and 10E, helium is mainly contained in the space S between the droplet ejection head 14 and the substrate 1, which reduces air resistance to the droplets I. Furthermore, by circulating ink through the droplet ejection head 14, the ejection state can be stabilized even if the solvent evaporates from the ink.

[0094] <Others> Here, a printing device that applies conductive ink to a printed circuit board has been described as the droplet ejection device, but the substrate and ink are not limited to this. The droplet ejection device can be applied to substrates with uneven surfaces, such as paper, cloth, leather, metal, resin, glass, and wood. The substrate is not limited to one that fits entirely within the chamber, but may be a long piece that extends inside and outside the chamber.

[0095] The droplet ejection device can use inks such as color inks containing coloring materials, ultraviolet curable inks that are cured by ultraviolet irradiation, insulating inks that have insulating properties, etc. The droplet ejection device can use the number of droplet ejection heads according to the type of ink, and multiple droplet ejection heads may be arranged in one chamber, or a chamber may be provided for each droplet ejection head.

[0096] The technical scope of the present invention is not limited to the scope described in the above embodiments. The configurations and the like in each embodiment can be appropriately combined with each other within the scope that does not deviate from the spirit of the present invention.

[0097] DESCRIPTION OF SYMBOLS 1...Substrate 10...Printing device 10A...Printing device 10B...Printing device 10C...Printing device 10D...Printing device 10E...Printing device 12...Transportation device 14...Droplet ejection head 15...Helium supply mechanism 16...L-shaped bracket 18...Ink supply path 18A...Ink supply port 20...Ink recovery path 20A...Ink discharge port 22...Filter housing 24...Silicon die 30...Chamber 31...Exhaust mechanism 32...Upper ink tank 34...Lower ink tank 36...Return flow path 38...Ink pump 38A...First ink pump 40...First valve 42...Refill ink tank 44...Refill flow path 46...Second ink pump 48...Second valve 50...Container 52...Control board 54...ASIC 56...Flexible cable 60A...Inlet slit 60B...Exit slit 62A...Inlet shutter 62B...Exit shutter 64A...First shutter 64B...Second shutter 64C...Third shutter 64D...Fourth shutter 66A...First adjustment chamber 66B...Second adjustment chamber 70...Control device 70A...Processor 70B...Memory 72...First up-and-down movement mechanism 74...Second up-and-down movement mechanism 76...First liquid level sensor 78...Second liquid level sensor 80...Concentration sensor 82...Solvent addition device 84...Ink cooling mechanism 200...Nozzle surface 202...Nozzle 204...Pressure chamber 206...Ink chamber unit 210...Supply branch 212...Common flow path 214...Descender 216...Ink circulation path 218...Recovery branch 220...Circulation common flow path 222...Ejection element 226...Vibration plate 228... Piezoelectric actuator 230... Nozzle plate 232... Flow path plate I... Droplet S... Space

Claims

1. A droplet ejection head that ejects liquid; a relative movement mechanism for moving the substrate and the droplet discharge head relative to each other; a control device that prints an image on the substrate by moving the substrate and the droplet ejection head relative to each other and ejecting liquid from the droplet ejection head; Equipped with a low-density gas having a density lower than that of air is contained between the droplet discharge head and the substrate; the droplet discharge head includes a circulation flow path therein, The control device circulates liquid through the circulation flow path at least during printing. Droplet ejection device.

2. the droplet ejection head has an ejection element including a nozzle, a pressure chamber, and an ejection energy generating element; the circulation flow path includes a supply flow path that supplies liquid to the ejection element, and a recovery flow path that recovers liquid from the ejection element. The droplet ejection device according to claim 1 .

3. the control device makes the amount of circulation of the liquid during printing greater than the amount of circulation of the liquid during non-printing; The droplet ejection device according to claim 1 .

4. The control device stops the circulation of the liquid when printing is not being performed. The droplet ejection device according to claim 1 .

5. the control device applies vibration to non-ejecting nozzles during printing to a degree that prevents droplets from being ejected; The droplet ejection device according to claim 1 .

6. a supply mechanism for supplying the low-density gas between the droplet discharge head and the substrate, the supply mechanism stops supplying the low-density gas during printing; The droplet ejection device according to claim 1 .

7. a chamber that accommodates the droplet ejection head and the relative movement mechanism therein; The chamber has an inlet slit through which the substrate is carried in and an outlet slit through which the substrate is discharged, and the inlet slit and the outlet slit are each provided with a shutter that can be opened and closed. The droplet ejection device according to claim 1 .

8. A chamber that accommodates the droplet ejection head and the relative movement mechanism therein, the liquid comprises a solvent; placing the solvent in an open state within the chamber; The droplet ejection device according to claim 1 .

9. A supply mechanism for supplying the low-density gas between the droplet discharge head and the substrate, the liquid comprises a solvent; The supply mechanism supplies the low density gas containing the solvent gas. The droplet ejection device according to claim 1 .

10. The liquid is an aqueous ink containing water as a solvent. The droplet ejection device according to claim 1 .

11. Supplying a low-density gas having a density lower than that of air between the droplet ejection head and the substrate; printing an image on the substrate by discharging liquid from the droplet discharge head while moving the substrate and the droplet discharge head relative to each other; circulating liquid through a circulation flow path of the droplet ejection head at least during printing; A method for producing a printed matter comprising the steps of: