JP2017024217A - Printing system, printing device, printing method and ink supply method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform supply of ink to an ink jet head more properly.SOLUTION: A printing system comprises: an ink jet head 102; an ink container; a first ink flow channel 122; and a second ink flow channel 124. The first ink flow channel 122 includes: a liquid feeding pump 302 being liquid feeding means; a deaeration module 304 being deaeration means; a sub-tank 310; and a pressure damper 312 being a pressure adjustment part. The sub-tank 310 feeds ink to the pressure damper 312 with the liquid head difference. One end of the second ink flow channel 124 is connected to the sub-tank 310, any position on the downstream side with respect to the sub-tank 310 in the first ink flow channel 122 or the ink jet head 102, and the other end is connected to any position between the ink container and the deaeration module 304 or the ink container. The second ink flow channel 124 flows the ink from the one end side to the other end side.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a printing system, a printing apparatus, a printing method, and an ink supply method.

  Conventionally, an ink jet printer that performs printing by an ink jet method has been widely used (see, for example, Patent Document 1). As a configuration of an inkjet printer, a configuration in which ink is supplied from an ink container to an inkjet head is known. For example, an ink bottle is used as such an ink container.

Japanese Patent No. 5400463

  When printing by the inkjet method, various conditions are desired for the flow path of the ink sent to the inkjet head. For example, when printing is performed by an ink jet method, if there is a large amount of air (oxygen or the like) dissolved in the ink, ejection failure or the like may occur. Therefore, it is desirable to degas the ink supplied to the inkjet head in advance. In addition, it is desired to appropriately supply ink according to the progress of the printing operation so as not to cause a shortage of ink during the printing operation. Further, in order to prevent unnecessary ink from leaking from the nozzles of the ink jet head, it is desirable to adjust the pressure of the ink chamber in front of the nozzles to a negative pressure lower than atmospheric pressure. Moreover, it is desirable to realize these conditions without significantly increasing the cost.

  For this reason, conventionally, it has been desired to more appropriately supply ink to the inkjet head with respect to a configuration in which printing is performed by the inkjet method. SUMMARY An advantage of some aspects of the invention is that it provides a printing system, a printing apparatus, a printing method, and an ink supply method that can solve the above-described problems.

  In addition, as a result of an investigation after the completion of the present invention, the above-mentioned Patent Document 1 that is similar in structure to the present invention was found. Patent Document 1 discloses a configuration in which an ink circulation path is provided for the purpose of preventing precipitation of ink coloring material. However, as is apparent from the features of the present invention described below, the present invention and Patent Document 1 have completely different purposes. As a result, the specific configuration also differs in various ways.

  The inventor of the present application has earnestly studied the configuration for supplying ink to the inkjet head. More specifically, an ink container provided outside the ink jet head is used, and in the ink flow path from the ink container to the ink jet head, the ink is deaerated using a deaeration means such as a deaeration module. We have conducted earnest research on the cases to be performed. If comprised in this way, it can deaerate appropriately about the ink supplied to an inkjet head. In addition, for example, for the ink stored in the ink container, ink that has not been degassed can be used. Further earnest research has led to the present invention that can appropriately supply ink to the inkjet head while suppressing the cost of the apparatus. In order to solve the above problems, the present invention has the following configuration.

  (Configuration 1) A printing system that performs printing by an inkjet method, an inkjet head that ejects ink droplets, an ink container that stores ink, and an ink flow path that connects the ink container and the inkjet head. A first ink flow path for flowing ink from the container toward the ink jet head, and a second ink flow that is a flow path of ink for flowing ink from either position in the first ink flow path or the ink jet head closer to the ink container The first ink flow path includes a liquid feeding means for sending ink in a direction from the ink container toward the ink jet head, a deaeration means for degassing the ink flowing through the first ink flow path, and a deaeration means. A sub-tank that is a reservoir for storing degassed ink, and is disposed between the sub-tank and the inkjet head. A pressure adjusting unit that adjusts a supply pressure at which ink is supplied to the ink jet head, and the sub tank, the pressure adjusting unit, and the ink jet head are connected to the ink jet head from the upstream side that is the ink container side in the first ink flow path. The pressure adjusting units are arranged in this order toward the downstream side, and are arranged below the sub tank in the gravitational direction so that at least a part of the stored ink is in contact with the atmosphere. In addition, at least a part is open to the atmosphere, and the ink is sent to the pressure adjusting unit due to a water head difference, and one end of the second ink flow path is one of the sub tank and the downstream side of the sub tank in the first ink flow path. Or the other end of the second ink flow path is located at any position between the ink container and the deaeration module, or It is connected to the ink container, the second ink flow path to flow the ink from the side of the one end toward the other end.

  In this configuration, the ink container is, for example, a container that stores ink at the most upstream part of the ink flow path. As the ink container, it is preferable to use a replaceable container. More specifically, as the ink container, for example, an ink bottle or an ink tank (main tank) can be suitably used. In this configuration, the ink is deaerated by the deaeration means. Therefore, the ink container may be a container in which the ink inside is in contact with the atmosphere. In addition, in this configuration, the sub tank is an ink storage portion provided separately from an ink container for storing ink in an upstream portion of the ink flow path, for example.

  Moreover, as a liquid feeding means, a pump can be used suitably, for example. As the deaeration means, for example, a replaceable deaeration module can be suitably used. The deaeration means is provided in the first ink channel, for example, to remove dissolved oxygen in the ink channel. In the first ink flow path, either the liquid feeding unit or the deaeration unit may be provided on the upstream side.

  In such a configuration, the degassed ink can be appropriately supplied to the inkjet head by degassing the ink in the first ink flow path. In addition, by providing the pressure adjustment unit in the front stage of the inkjet head, the supply pressure at which ink is supplied to the inkjet head can be appropriately adjusted. Therefore, if comprised in this way, discharge of an ink drop can be stably performed appropriately by an inkjet head, for example.

  Further, in this configuration, by providing a sub-tank in front of the pressure adjustment unit, it is possible to quickly and surely supply ink to the inkjet head when ink droplets are ejected by the inkjet head. This also makes it possible to stably and appropriately supply ink to the inkjet head.

  In addition, the ink supply from the sub tank to the pressure adjusting unit is performed using the ink head difference, thereby simplifying the configuration of the apparatus and appropriately reducing the cost of the apparatus. Therefore, with this configuration, for example, stable supply of deaerated ink and stable ejection of ink droplets by the ink jet head can be appropriately realized while suppressing the cost of the apparatus.

  Here, in the first ink flow path, the sub tank is provided on the downstream side of the deaeration means. Thereby, the sub tank stores the ink deaerated by the deaeration means as described above. Then, the stored ink is supplied to the pressure adjusting unit using the water head difference of the ink. If comprised in this way, even when the pressure loss which arises in a deaeration means is large, for example, the supply of the ink to an inkjet head can be performed stably, without being influenced by pressure loss.

  Further, in this configuration, at least a part of the sub tank is opened to the atmosphere in order to supply ink by a water head difference. Therefore, in the first ink flow path, the ink comes into contact with the atmosphere again after being deaerated by the deaeration means. In this case, for example, if ink is merely stored in the sub tank, air (oxygen or the like) may be dissolved in the ink if the ink is stored in the sub tank for a long time. As a result, the ejection of ink droplets by the ink jet head may become unstable.

  On the other hand, in this configuration, not only the ink is stored in the sub tank, but also the second ink flow path is used to circulate the ink from the position below the sub tank to the position upstream of the deaeration means. I am letting. According to this configuration, for example, by providing an ink circulation path via the deaeration unit, even when air is dissolved again in the ink in the sub tank, the ink can be passed through the deaeration unit again. . This also makes it possible to degas the ink more appropriately.

  Therefore, with this configuration, for example, the ink is deaerated by the deaeration means, the ink supply pressure to the inkjet head is adjusted by the pressure adjustment unit, and the pressure adjustment from the sub tank by the ink head difference Supplying ink to the section can be performed in an appropriate combination. Accordingly, as described above, for example, stable supply of deaerated ink and stable discharge of ink droplets by the ink jet head can be appropriately realized while suppressing the cost of the apparatus.

  In this configuration, the printing system may perform printing using, for example, a plurality of types of inks having different colors. In this case, the printing system includes, for example, a plurality of ink containers that store different colors of ink. In addition, the ink jet head, the first ink flow path, the second ink flow path, and the like are provided for each ink color with ink supply and ink discharge configurations.

  (Configuration 2) The inkjet head has a nozzle that ejects ink droplets and an ink chamber that stores ink at a position adjacent to the nozzle, and the pressure adjustment unit is a pressure at which ink is supplied to the ink chamber in the inkjet head The ink supply pressure to the inkjet head is adjusted so that the pressure becomes lower than the atmospheric pressure. If comprised in this way, the supply pressure of an ink can be adjusted appropriately, for example.

  (Configuration 3) The pressure adjusting unit is a mechanical pressure damper. The mechanical pressure damper is, for example, a configuration that adjusts the pressure mechanically without using a pressure adjusting pump or the like. As the mechanical pressure damper, for example, a configuration in which a thin film disposed so as to be in contact with the ink path is biased by a biasing member such as a spring may be used. If comprised in this way, adjustment of the supply pressure of an ink can be performed appropriately at low cost, for example.

  (Configuration 4) The inkjet head is disposed below the pressure adjusting unit in the direction of gravity. If comprised in this way, the supply of the ink from a pressure adjustment part to an inkjet head can be performed more appropriately, for example.

  (Structure 5) Main scanning that discharges ink droplets while moving in the main scanning direction by moving the carriage in the main scanning direction set in advance by moving the carriage in the main scanning direction by facing the medium to be printed and holding the inkjet head A main scanning drive unit that causes the ink jet head to perform an operation, and the sub tank and the pressure adjusting unit are held together with the ink jet head by the carriage. During the main scanning operation, the sub tank and the pressure adjusting unit are operated together with the ink jet head. Move in the scanning direction.

  With this configuration, for example, in the case of performing printing by a serial method that causes the ink jet head to perform a main scanning operation, the sub tank, the pressure adjusting unit, and the ink jet head can be installed close to each other. In addition, this makes it possible to more stably supply ink to the inkjet head. Furthermore, in this case, for example, since the ink is supplied from the sub tank to the pressure adjusting unit using the water head difference, the configuration arranged on the carriage is prevented from being complicated and the weight from being excessively increased. You can also.

  (Configuration 6) The liquid feeding means and the deaeration means are disposed outside the carriage. In this case, for example, the liquid feeding unit and the deaeration unit are installed at a predetermined fixed position so as not to move during the main scanning operation.

  If comprised in this way, the complication of the structure arrange | positioned on a carriage, the excessive increase in a weight, etc. can be prevented more appropriately, for example. Also, in this case, by using a configuration in which the ink is circulated in the second ink flow path, the degassing means is disposed outside the carriage, so that the ink can be removed even if the degassing means and the inkjet head are separated. You can do it properly. Therefore, with this configuration, for example, when printing is performed in a serial system, it is possible to more appropriately supply ink to the inkjet head.

  (Configuration 7) The liquid feeding means is a tubing pump, and the deaeration means is disposed downstream of the liquid feeding means in the first ink path. In such a configuration, for example, by performing deaeration at a position closer to the inkjet head, the degassed ink can be more appropriately supplied to the inkjet head. Further, for example, when air is dissolved in the ink at the time of liquid feeding by the liquid feeding means, it can be appropriately deaerated by the degassing means on the downstream side. Therefore, if comprised in this way, deaeration of ink can be performed more reliably, for example.

  Here, the tubing pump is, for example, a pump configured to perform liquid feeding by squeezing a tube. Therefore, the tubing pump is usually configured to pass ink through a flexible tube. However, permeability to air such as oxygen using a flexible tube is high, and it is difficult to provide sufficient gas barrier properties. For this reason, when a tubing pump is disposed on the downstream side of the deaeration means, oxygen or the like is easily dissolved again in the degassed ink. On the other hand, if comprised in this way, even if it uses a flexible tube with low gas barrier property in a tubing pump, it can deaerate appropriately by a deaeration means after that. Thereby, as described above, for example, ink can be deaerated more reliably.

  (Configuration 8) The volume of the sub tank is smaller than that of the ink container, and the other end of the second ink channel is connected to the downstream side of the ink container in the first ink channel. In such a configuration, for example, the position where the ink is circulated using the second ink flow path is not returned to the ink container but is positioned downstream of the ink container so that the ink is circulated and removed. Time to worry about can be shortened appropriately. Further, in this case, by further reducing the capacity of the sub tank, for example, the amount of ink (ink in the sub tank) that needs to be circulated using the second ink flow path can be appropriately reduced. Therefore, also in this respect, the time required for ink circulation and deaeration can be appropriately shortened.

  (Configuration 9) The second ink flow path has a valve that opens and closes the ink flow path, and the valve is in an open state during a standby time when the printing operation by the inkjet head is not performed. 2 Ink flows in the ink flow path. With this configuration, for example, ink can be appropriately circulated during the standby time. In addition, this allows the ink in the sub tank to be appropriately deaerated before starting the next printing operation.

  During the standby time, for example, the valve may be opened every time a fixed time elapses, and ink may flow through the second ink flow path. If comprised in this way, deaeration can be performed for every fixed time with respect to the ink in a sub tank, for example.

  For example, it is preferable that the valve is in a closed state at least at the timing when the ink jet head ejects ink droplets. If comprised in this way, it can prevent that the ink in a sub tank reduces by the outflow to a 2nd ink flow path during printing operation. Thereby, for example, ink can be more appropriately supplied to the inkjet head.

  (Configuration 10) A printing apparatus that performs ink jet printing using ink supplied from an ink container, and includes an ink jet head that ejects ink droplets, and an ink flow path that connects the ink container and the ink jet head. A first ink flow path for flowing ink from the ink container toward the ink jet head, and a second ink flow path for flowing ink from a position in the first ink flow path or the ink jet head closer to the ink container. An ink flow path, and the first ink flow path includes a liquid feeding means for sending ink in a direction from the ink container toward the ink jet head, a deaeration means for degassing the ink flowing through the first ink flow path, and a deaeration. Between the sub tank and the ink jet head, which is a storage section for storing the ink deaerated by the means. A sub-tank, a pressure adjusting unit, and an ink-jet head that perform ink jet from an upstream side that is the ink container side in the first ink flow path. The pressure adjusting units are arranged in this order toward the downstream side, which is the head side, and the pressure adjusting unit is disposed below the sub tank in the gravitational direction, and the sub tank has at least a part of the stored ink as the atmosphere. At least a part is open to the atmosphere so as to come into contact, and the ink is sent to the pressure adjusting unit due to a water head difference, and one end of the second ink channel is located on either the sub tank or the downstream side of the sub tank in the first ink channel. Or the other end of the second ink flow path is located between the ink container and the deaeration module. , Or it is connected to the ink container, the second ink flow path to flow the ink from the side of the one end toward the other end. If comprised in this way, the effect similar to the structure 1 can be acquired, for example.

  (Configuration 11) A printing method for performing printing by an ink jet method using ink supplied from an ink container, wherein the ink is supplied to the ink jet head that ejects ink droplets, and the ink that connects the ink container and the ink jet head A first ink flow path for flowing ink from the ink container toward the ink jet head, and an ink flow for flowing ink from either position in the first ink flow path or the ink jet head closer to the ink container The first ink channel degasses the ink flowing in the first ink channel and the liquid feeding means for sending the ink in the direction from the ink container to the inkjet head. A deaeration unit, a sub tank which is a storage unit for storing the ink deaerated by the deaeration unit, and the sub tank and the ink tank. A sub-tank, a pressure adjusting unit, and an ink-jet head are arranged between the ink head and the ink-jet head. Are arranged in this order from the upstream side, which is the ink jet head side, to the downstream side, which is the ink jet head side, and the pressure adjusting unit is disposed below the sub tank in the gravitational direction. At least a part of the second ink channel is opened to the atmosphere so that at least a part of the second ink channel is in contact with the atmosphere. Connected to any position downstream of the sub tank or to the inkjet head, the other end of the second ink flow path is connected to the ink container and the deaeration module. Any position between the, or connected to an ink container, the second ink flow path to flow the ink from the side of the one end toward the other end. If comprised in this way, the effect similar to the structure 1 can be acquired, for example.

  (Configuration 12) An ink supply method for supplying ink from an ink container that stores ink to an inkjet head that ejects ink droplets by an inkjet method, wherein the ink flow path connects the ink container and the inkjet head. A first ink channel that causes ink to flow from the ink container toward the inkjet head, and a second ink that is an ink channel that causes ink to flow from either position in the first ink channel or the inkjet head to a side closer to the ink container. The first ink channel includes a liquid feeding unit that sends ink in a direction from the ink container toward the ink jet head, a deaeration unit that degass the ink flowing through the first ink channel, and a deaeration unit. Between the subtank and the inkjet head, which is a reservoir for storing the ink degassed by the A sub-tank, a pressure adjusting unit, and an ink jet head, which are upstream of the ink container in the first ink flow path, and a pressure adjusting unit that adjusts a supply pressure for supplying ink to the ink jet head. Are arranged in this order from the inkjet head toward the downstream side, and the pressure adjustment unit is disposed below the sub tank in the direction of gravity, and the sub tank contains at least a part of the stored ink. At least a part is opened to the atmosphere so as to be in contact with the atmosphere, and the ink is sent to the pressure adjusting unit due to a water head difference. One end of the second ink channel is downstream of the sub tank and the sub tank in the first ink channel. Or the other end of the second ink flow path is either between the ink container and the deaeration module. Position, or connected to an ink container, the second ink flow path to flow the ink from the side of the one end toward the other end. If comprised in this way, the effect similar to the structure 1 can be acquired, for example.

  According to the present invention, for example, it is possible to more appropriately supply ink to an inkjet head.

1 is a diagram illustrating an example of a configuration of a printing system 10 according to an embodiment of the present invention. 2 is a diagram illustrating an example of the configuration of an ink supply path 114 together with an inkjet head 102 and a carriage 104. FIG. It is a figure which shows an example of control of a valve | bulb. FIG. 10 is a diagram illustrating a modified example of the configuration of the ink supply path 114.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. FIG. 1 shows an example of the configuration of a printing system 10 according to an embodiment of the present invention. The printing system 10 is a printing system that performs printing on the medium 50 by an inkjet method, and includes a main body unit 12 and an ink supply unit 14.

  The main body 12 is a main body of a printing apparatus that performs ink jet printing, and includes an ink jet head 102, a carriage 104, a guide rail 106, a medium support 108, a main scanning driving unit 110, a sub scanning driving unit 112, and an ink supply path. 114 and a control unit 116.

  The ink jet head 102 is a print head that ejects ink droplets by an ink jet method. In this example, the ink jet head 102 includes, for example, a nozzle that ejects ink droplets and an ink chamber that stores ink at the front stage of the nozzle. The ink jet head 102 may have a plurality of nozzles. In this case, the inkjet head 102 has an ink chamber corresponding to each nozzle at a position adjacent to each nozzle.

  The carriage 104 is a holding member that holds the inkjet head 102 so as to face the medium 50 to be printed. In this example, the carriage 104 holds a part of the configuration of the ink supply path 114 together with the inkjet head 102. The configuration held by the carriage 104 will be described in more detail later.

  The guide rail 106 is a rail that guides the movement of the carriage 104 in a preset main scanning direction (Y direction in the drawing). The medium support unit 108 is a support member that supports the medium 50 by placing the medium 50 on the upper surface. The medium support unit 108 may be a plate-like member such as a platen.

  The main scanning drive unit 110 is a driving unit that causes the inkjet head 102 to perform a main scanning operation of ejecting ink droplets while moving in the main scanning direction. In this example, the main scanning driving unit 110 moves the carriage 104 in the main scanning direction along the guide rail 106, thereby moving the inkjet head 102 and the like held by the carriage 104 in the main scanning direction. Further, the ink jet head 102 is caused to perform a main scanning operation by ejecting ink droplets onto the moving ink jet head 102. Accordingly, the main scanning drive unit 110 causes the main body unit 12 to execute a serial printing operation.

  The sub-scanning drive unit 112 is a drive unit that causes the inkjet head 102 to perform a sub-scanning operation. In this case, causing the inkjet head 102 to perform the sub-scanning operation means, for example, moving the inkjet head 102 relative to the medium 50 in the sub-scanning direction (X direction in the drawing) orthogonal to the main scanning operation. It is. In this example, the sub-scan driving unit 112 moves the inkjet head 102 relative to the medium 50 by, for example, conveying the medium 50 by a roller (not shown). Further, in a modification of the configuration of the main body unit 12, for example, the position of the medium 50 may be fixed and the ink jet head 102 may be moved by moving the ink jet head 102 side. In this case, the sub-scan driving unit 112 moves the inkjet head 102 together with the guide rail 106 and the carriage 104 by moving the guide rail 106, for example.

  The ink supply path 114 is an ink path for sending the ink supplied from the ink supply unit 14 to the inkjet head 102. The configuration of the ink supply path 114 will be described in more detail later.

  The control unit 116 is, for example, a CPU of the main body unit 12, and controls the operation of each unit of the main body unit 12 to cause the main body unit 12 to perform a printing operation. In this case, more specifically, as an example of the control of the operation of each unit, the control unit 116 controls the ink supply operation through the ink supply path 114, for example. The control of the ink supply path 114 will be described in more detail later together with the configuration of the ink supply path 114.

  The ink supply unit 14 is an ink supply device that supplies ink to the main body unit 12. In this example, the ink supply unit 14 includes an ink container 202, a filter 204, and a valve 206. The ink container 202 is a container that stores ink at the most upstream part of the ink flow path in the printing system 10. More specifically, the ink container 202 is, for example, an ink bottle or an ink tank (main tank). As the ink container 202, a replaceable container is preferably used. Further, as will be described in detail later, in this example, the ink is deaerated in the middle of the ink supply path 114. Therefore, the ink container 202 may store ink in which air (oxygen or the like) is dissolved. Further, the ink container 202 may be, for example, a container in which the internal ink comes into contact with the atmosphere.

  Further, it is preferable to use a container having a sufficiently large volume as the ink container 202 so that the ink can be continuously supplied to the main body 12 for a long time. More specifically, as the ink container 202, it is preferable to use a container having a volume of 2L or more (for example, 2 to 3L), preferably 3L or more.

  The filter 204 is a filter that removes impurities in the ink in the ink flow path in the ink supply unit 14. In this case, the ink flow path in the ink supply unit 14 is, for example, an ink flow path that connects the ink supply path 114 in the main body 12 and the ink container 202. The valve 206 is a valve that opens and closes the ink flow path in the ink supply unit 14. According to this example, for example, the main body 12 can appropriately perform printing using the ink supplied from the ink supply unit 14.

  In this example, the main body unit 12 and the ink supply unit 14 are configured as separate devices, for example. Further, in the modified example of the configuration of the printing system 10, the main body 12 and the ink supply unit 14 may be separated by a portion different from the configuration illustrated in FIG. Each of the main body 12 and the ink supply unit 14 may be a part of one apparatus. Further, except for the points described above and below, the printing system 10, the main body unit 12, and the ink supply unit 14 are the same as or similar to known printing systems, printing devices, and ink supply devices that perform printing by an inkjet method. It may have the following features.

  Further, in this example, as the ink used for printing, for example, various known inks can be suitably used. In this case, the main body 12 preferably further has a configuration corresponding to the type of ink to be used. For example, when an ultraviolet curable ink (UV ink) or a solvent UV ink that is an ink that is cured by irradiation with ultraviolet rays is used, the main body 12 preferably further includes an ultraviolet light source. When using ink that requires heating of the medium 50, such as solvent ink, latex ink, or solvent UV ink, the main body 12 preferably further includes a heater that heats the medium 50.

  In FIG. 1, only the configuration necessary when using one color ink is illustrated for convenience of explanation. However, in the printing system 10, printing may be performed using a plurality of types of inks having different colors. In this case, for example, the printing system 10 includes a configuration that needs to be provided for each color according to the maximum number of colors used for printing. More specifically, in this case, the main body unit 12 includes, for example, a plurality of ink supply paths 114 and the inkjet head 102. The ink supply unit 14 includes a plurality of ink containers 202, filters 204, and valves 206.

  Next, a more specific configuration of the ink supply path 114 will be described. FIG. 2 shows an example of the configuration of the ink supply path 114 together with the inkjet head 102 and the carriage 104. In this example, the ink supply channel 114 includes a first ink channel 122, a second ink channel 124, a module suction unit 306, an overflow detection unit 314, and a valve 316.

  The first ink flow path 122 is an ink flow path for flowing ink in a direction from the ink supply unit 14 toward the inkjet head 102, and includes a liquid feed pump 302, a deaeration module 304, a valve 308, a sub tank 310, and a pressure damper 312. Have In the first ink flow path 122, these components are arranged in this order from the upstream side to the downstream side as shown in the figure. In this case, the upstream side is the ink container 202 side in the path through which ink flows from the ink supply unit 14 toward the inkjet head 102. Further, the downstream side is the ink jet head 102 side.

  In addition, the above-described components in the first ink flow path 122 are connected by an ink transport path such as a tube. As a result, the first ink flow path 122 connects the ink container 202 (see FIG. 1) in the ink supply unit 14 and the inkjet head 102, and causes ink to flow from the ink container 202 toward the inkjet head 102.

  In the first ink flow path 122, the liquid feed pump 302 is an example of a liquid feed unit, and sends ink in a direction from the ink container 202 in the ink supply unit 14 toward the inkjet head 102. As the liquid feeding pump 302, for example, a tubing pump (tube pump) or the like can be suitably used. In addition to the tubing pump, for example, a diaphragm pump or a positive displacement pump may be used as the liquid feed pump 302.

  The deaeration module 304 is an example of a deaeration unit, and degass the ink flowing through the first ink flow path 122. As the deaeration module 304, for example, a configuration for performing deaeration using a hollow fiber membrane can be suitably used. Further, in this example, the deaeration module 304 causes the ink (air) to flow from the ink flowing along the ink flow path 122 by flowing ink along the first ink flow path 122 while being sucked by the module suction portion 306. Remove dissolved oxygen). The deaeration module 304 is a replaceable part, and is replaced every time it is used for a certain period, for example.

  Note that the first ink flow path 122 may include a plurality of deaeration modules 304. In this case, the plurality of deaeration modules 304 are connected in parallel in the ink flow path, for example. If comprised in this way, the influence of the pressure loss which arises in the deaeration module 304 can be reduced appropriately, for example.

  The valve 308 is a valve that opens and closes the first ink flow path 122. In this example, the valve 308 is disposed between the deaeration module 304 and the sub tank 310, and opens the first ink flow path 122 when printing is performed by the main body 12. Further, the first ink flow path 122 is closed when the main body 12 is turned off. Further, when performing operations such as ink filling and cleaning, the first ink flow path 122 is opened and closed as necessary.

  The sub tank 310 is a small storage unit that stores ink in the vicinity of the inkjet head 102, and stores the ink deaerated by the deaeration module 304 by being disposed downstream of the deaeration module 304. To do. In this case, the sub tank is, for example, a small tank having a smaller volume than the ink container 202. In this example, the sub tank 310 is much smaller than the ink container 202 and is disposed on the carriage 104. The volume of the sub tank 310 is preferably about 40 cc (for example, about 20 to 100 cc, preferably about 30 to 50 cc).

  In this example, at least a part of the sub tank 310 is open to the atmosphere so that at least a part of the stored ink is in contact with the atmosphere. More specifically, in this example, when the valve 316 is open, a part of the sub tank 310 is opened to the atmosphere via the overflow detection unit 314 and the valve 316. Accordingly, the sub tank 310 sends ink to the pressure damper 312 on the downstream side due to the ink head difference. The sub tank 310 preferably includes a float sensor that detects the amount of ink inside.

  The pressure damper 312 is an example of a pressure adjusting unit, and is disposed between the sub tank 310 and the inkjet head 102 below the sub tank 310 in the direction of gravity. Accordingly, the pressure damper 312 is disposed on the carriage 104 together with the sub tank 310. In this example, the pressure damper 312 is a mechanical pressure damper, and mechanically adjusts the supply pressure at which ink is supplied to the inkjet head 102. In this case, the mechanical pressure damper is a configuration that adjusts the pressure mechanically without using, for example, a pressure adjusting pump. More specifically, as the mechanical pressure damper, for example, a configuration in which a thin film disposed so as to be in contact with the ink path is biased by a biasing member such as a spring can be used.

  As the pressure damper 312, for example, a known pressure damper used in an ink jet printer can be suitably used. As such a known pressure damper, for example, a pressure regulating damper described in JP 2011-46070 A can be used. In this example, the pressure damper 312 adjusts the supply pressure of ink to the inkjet head 102 so that the pressure at which ink is supplied to the ink chamber in the inkjet head becomes a pressure (negative pressure) lower than atmospheric pressure. To do.

  As the pressure damper 312, for example, a pressure damper having a volume of about 5 cc (for example, about 2 to 15 cc, preferably about 3 to 10 cc) is preferably used. If comprised in this way, the pressure of the ink chamber in the inkjet head 102 can be adjusted appropriately, for example.

  If configured as described above, the first ink flow path 122 can appropriately supply ink from the ink container 202 to the inkjet head 102, for example. Further, as described above, in this example, the ink supply path 114 further includes the second ink flow path 124 in addition to the first ink flow path 122. The second ink flow path 124 is a flow path for circulating ink by flowing ink in a direction opposite to the first ink flow path 122, and either of the first ink flow path 122 or the ink jet head 102 is used. Ink is allowed to flow from the position closer to the ink container 202.

  More specifically, in this example, one end of the second ink flow path 124 is connected to the sub tank 310. The other end is connected between the ink supply unit 14 and the liquid feed pump 302. Accordingly, the second ink flow path 124 causes the ink in the sub tank 310 to circulate to a position closer to the ink supply unit 14 than the deaeration module 304. With this configuration, for example, the ink in the sub tank 310 can be returned to the upstream side through the deaeration module 304 again by the second ink flow path 124. In addition, for example, the ink once supplied to the vicinity of the inkjet head 102 can be deaerated again as necessary.

  In this example, the second ink channel 124 has a valve 318 that opens and closes the ink channel. For example, the valve 318 is opened during a standby time when the printing operation by the inkjet head 102 is not performed, and causes the ink to flow through the second ink flow path 124. With this configuration, for example, ink can be appropriately circulated during the standby time. In addition, this allows the ink in the sub tank 310 to be appropriately degassed before starting the next printing operation.

  Note that during the standby time, the valve 318 may be opened each time a certain time elapses, for example, and ink may flow through the second ink flow path 124. If comprised in this way, deaeration can be performed for every fixed time with respect to the ink in the sub tank 310, for example.

  Further, for example, it is preferable that the valve 318 is in a closed state at least at the timing when the ink jet head 102 ejects ink droplets (during printing). With this configuration, it is possible to prevent the ink in the sub tank 310 from being reduced due to the outflow to the second ink flow path 124 during the printing operation. This also makes it possible to more appropriately supply ink to the inkjet head 102, for example.

  Further, as described above, in this example, the ink supply path 114 includes the module suction unit 306, the overflow detection unit 314, and the valve in addition to the first ink channel 122 and the second ink channel 124. 316 is further included. The module suction unit 306 is configured to suck the deaeration module 304. More specifically, the module suction unit 306 has a configuration including, for example, a vacuum pump that sucks the deaeration module 304. The module suction unit 306 may further include, for example, a chamber provided between the deaeration module 304 and the vacuum pump, a leak sensor that detects leakage of liquid from the vacuum pump, and the like.

  The overflow detection unit 314 is a detection unit that detects that the ink overflows from the sub tank 310. For example, when the ink in the sub tank 310 overflows due to an operation abnormality of the main body 12, the abnormality is detected. The overflow detection unit 314 may be, for example, a part having an overflow detection sub-tank different from the sub-tank 310, a backflow prevention filter, and the like. In this case, the sub tank for detecting overflow is a small tank into which ink flows when ink overflows from the sub tank. The sub tank for detecting overflow has a float sensor that detects the amount of ink inside, and detects that ink flows from the sub tank 310. The backflow prevention sensor is disposed between the overflow detection subtank and the valve 316, and prevents backflow of ink when, for example, the ink in the subtank 310 is sucked.

  The valve 316 is a valve that opens and closes between the overflow detection unit 314 and the atmosphere. In this example, the sub tank 310 is connected to the outside atmosphere via the overflow detection unit 314 and the valve 316. Therefore, the sub tank 310 can be opened to the atmosphere by opening the valve 316.

  Next, various effects obtained by the configuration of this example will be described. According to this example, for example, by degassing ink in the first ink flow path 122, the degassed ink can be appropriately supplied to the inkjet head 102. Further, by providing the pressure damper 312 in front of the inkjet head 102, the ink supply pressure to the inkjet head 102 can be appropriately adjusted. Accordingly, for example, ink droplets can be ejected stably and appropriately by the inkjet head 102.

  As described above, as the pressure damper 312, it is conceivable to use a pressure damper having a very small volume, for example, a volume of about 5 cc. For this reason, simply using the pressure damper 312 may cause the pressure damper 312 to be emptied when a large amount of ink is ejected from the inkjet head 102, resulting in ejection failure.

  On the other hand, in this example, a sub-tank 310 having a larger volume than the pressure damper 312 is disposed on the carriage 104 in front of the pressure damper 312. Accordingly, for example, when ink droplets are ejected by the ink jet head 102, ink can be supplied to the ink jet head 102 quickly and reliably. Therefore, according to this example, for example, even when the amount of ink ejected by the ink jet head 102 is large, the pressure damper 312 is appropriately prevented from being emptied, and the ink jet head 102 is appropriately prevented from causing ejection failure. Can be prevented. This also makes it possible to stably and appropriately supply ink to the inkjet head 102.

  Further, the ink supply from the sub tank 310 to the pressure damper 312 is performed using the ink head difference, thereby simplifying the configuration of the apparatus and appropriately reducing the cost of the apparatus. Therefore, according to this example, for example, stable supply of deaerated ink and stable ejection of ink droplets by the inkjet head 102 can be appropriately realized while suppressing the cost of the apparatus.

  In order to adjust the ink chamber of the inkjet head 102 to a negative pressure, for example, instead of using the pressure damper 312 as in this example, the sealed sub tank 310 is used, and the pressure in the 301 is adjusted by a pump or the like. It is also conceivable to do so. However, when such a method is used, the apparatus becomes complicated and the cost may increase significantly.

  In the first ink flow path 122 of this example, the sub tank 310 is provided on the downstream side of the deaeration module 304. With this configuration, for example, even when the pressure loss generated in the deaeration module 304 is large, ink can be stably supplied to the inkjet head 102 without being affected by the pressure loss.

  Further, as described above, in this example, at least a part of the sub tank 310 is open to the atmosphere. For this reason, in the first ink flow path 122, the ink comes into contact with the atmosphere again after being deaerated by the deaeration module 304. In this case, for example, if the time for storing ink in the sub tank 310 becomes long, it is conceivable that air (oxygen or the like) is dissolved again in the ink.

  On the other hand, in this example, the ink is circulated from the sub tank 310 to the position upstream of the deaeration module 304 using the second ink flow path 124. In such a configuration, for example, in a configuration in which ink is supplied from the sub tank 310 to the pressure damper 312 using a water head difference, the air is dissolved again in the ink stored in the sub tank 310. The ink can be passed again through the air module 304. In addition, for example, it is possible to appropriately degas the ink and appropriately prevent ejection failure due to the influence of dissolved oxygen or the like.

  As described above, in this example, by using the second ink flow path 124 in addition to the first ink flow path 122, the deaeration module 304 performs the deaeration of the ink, and the ink supply pressure to the inkjet head. The pressure damper 312 can be adjusted, and the ink can be supplied from the sub tank 310 to the pressure damper 312 by an ink head difference. Accordingly, for example, in addition to stable supply of deaerated ink, stable ejection of ink droplets by the inkjet head is further realized while suppressing the cost of the apparatus.

  In this example, the sub tank 310, the pressure damper 312, the overflow detection unit 314, and the valve 316 in the configuration of the ink supply path 114 are held by the carriage 104 together with the inkjet head 102. In this case, during the main scanning operation, the sub tank 310, the pressure damper 312 and the like move together with the inkjet head 102 in the main scanning direction.

  According to the present example, for example, in a configuration in which printing is performed in a serial system, the sub tank 310, the pressure damper 312 and the like and the inkjet head 102 can be installed close to each other. This also makes it possible to supply ink to the inkjet head 102 more stably. In addition, by appropriately using a configuration for supplying ink with a water head difference, it is possible to prevent complication of the configuration arranged on the carriage 104, an excessive increase in weight, and the like.

  In this case, the inkjet head 102 is preferably disposed below the pressure damper 312 in the gravitational direction. With this configuration, for example, ink can be more appropriately supplied from the pressure damper 312 to the inkjet head 102.

  Of the configuration of the ink supply path 114, the liquid feed pump 302, the deaeration module 304, the module suction unit 306, and the valve 308 are disposed outside the carriage 104. In this case, for example, these components are installed at predetermined fixed positions so as not to move during the main scanning operation. More specifically, these configurations are disposed in, for example, a maintenance unit near the side surface of the main body unit 12 adjacent to the ink supply unit 14.

  With this configuration, it is possible to appropriately prevent, for example, a complicated configuration arranged on the carriage 104 and an excessive increase in weight. In this example, since the configuration in which the ink is circulated in the second ink flow path 124 is used, the deaeration module 304 and the inkjet head 102 are separated by disposing the deaeration module 304 outside the carriage 104. Even so, the ink can be appropriately deaerated. Therefore, according to this example, for example, in a configuration in which printing is performed in a serial system, it is possible to more appropriately supply ink to the inkjet head 102.

  Further, as described above, the deaeration module 304 is disposed on the downstream side of the liquid feed pump 302 in the first ink flow path 122 of this example. Therefore, according to this example, the deaerated ink can be more appropriately supplied to the inkjet head 102 by performing deaeration at a position closer to the inkjet head 102, for example. Further, for example, when air is dissolved in the ink when the liquid is fed by the liquid feed pump 302, the deaeration module 304 on the downstream side can appropriately deaerate. Therefore, according to this example, for example, ink can be deaerated more reliably.

  Next, an example of the operation of each valve in the ink supply path 114 will be described regarding the control of the ink supply path 114. FIG. 3 shows an example of valve control performed in this example.

  In FIG. 3, V <b> 1 indicates the valve 206 (see FIG. 1) in the ink supply unit 14. Each of V2, V3, and V4 indicates the valve 318, the valve 308, and the valve 316 (see FIG. 2) in the ink supply path 114, respectively.

  As shown in the figure, in this example, the state of each valve is made different according to each operation such as power OFF state, local state, printing, flushing, cleaning, ink filling, sub tank circulation, etc. . Of these states, the power-off state is a state in which the printing system 10 is turned off. In this case, the control unit 116 (see FIG. 1) closes all the valves. The local state is a state in which a local mode for directly controlling the printing system 10 during maintenance or the like is set. In this case, the control unit 116 opens only V4 and closes the other valves.

  In addition, during printing, flushing, cleaning, and ink filling, the state of the valve is different depending on whether ink is not supplied (supply Off) and when it is supplied (supply On). In this case, the time of printing is the time of executing a printing operation by the inkjet head 102 (see FIG. 1). The flushing is an operation of ejecting ink droplets from the nozzles of the inkjet head 102 in order to clean the inkjet head 102 or the like.

  During printing and flushing, for example, when ink supply is temporarily stopped to adjust the ink supply amount, or when ink supply is stopped at the start or end of operation, etc. When ink is not supplied from the unit 14 to the inkjet head 102 (when supply is OFF), the control unit 116 opens only V4 and closes the other valves. When ink is supplied from the ink supply unit 14 to the inkjet head 102 (in the case of supply On), the control unit 116 closes only V2 and opens the other valves.

  The term “cleaning” refers to an operation for cleaning the inkjet head 102. The ink filling time is an operation for filling the ink supply path 114 with ink. When ink is not supplied from the ink supply unit 14 to the inkjet head 102 during cleaning and ink filling (when supply is OFF), the control unit 116 closes all the valves. As such a case, for example, a case where vacuuming is performed for a certain period in order to remove air in the ink supply path 114 during ink filling can be considered. When ink is supplied from the ink supply unit 14 to the inkjet head 102 (in the case of supply On), the control unit 116 closes only V2 and opens the other valves.

  The sub-tank circulation is an operation in which ink is circulated using the second ink flow path 124. In this case, the control unit 116 closes only V1 and opens the other valves. If comprised in this way, the ink in the ink supply path 114 can be circulated appropriately, for example. Accordingly, it is possible to appropriately deaerate again the ink in the ink supply path 114 by the deaeration module 304. If configured as described above, for example, various operations can be appropriately performed by the printing system 10.

  Next, a modified example of the configuration of the ink supply path 114 will be described. The specific configuration of the ink supply path 114 can be variously modified in addition to the configuration shown in FIG. For example, in FIG. 2, as an example of the configuration of the ink supply path 114, one end of the second ink flow path 124 is connected to the sub tank 310 and the other end is connected between the ink supply unit 14 and the liquid feed pump 302. I explained the case. However, if the configuration allows the ink stored in the sub-tank 310 to pass through the deaeration module 304 again, the position at which one end and the other end of the second ink flow path 124 are connected is different from the configuration in FIG. Is also possible. In this case, one end of the second ink flow path 124 may be connected to the inkjet head 102, for example, in addition to being directly connected to the sub tank 310 as shown in FIG. Further, for example, a connection between the sub tank 310 and the inkjet head 102 may be considered. Further, in a more generalized manner, one end of the second ink flow path 124 is connected to, for example, the sub tank 310, a position downstream of the sub tank 310 in the first ink flow path 122, or the inkjet head 102. It is possible to do.

  The other end of the second ink flow path 124 may be connected to any position between the ink container 202 and the deaeration module 304 in the ink supply unit 14 or to the ink container 202, for example. In this case, it is desirable that the other end of the second ink flow path 124 is not connected directly to the deaeration module 304 but connected to the upstream side of the deaeration module 304.

  Further, as described with reference to FIG. 1, in the printing system 10 (see FIG. 1) of this example, printing may be performed using a plurality of types of inks having different colors. In this case, for example, the printing system 10 includes a plurality of configurations that need to be provided for each color in accordance with the maximum number of colors used for printing. More specifically, in this case, the printing system 10 may include a plurality of ink supply paths 114 and inkjet heads 102 in accordance with the number of inks used.

  Further, for example, FIG. 2 shows a configuration in which the liquid feed pump 302 is disposed upstream of the deaeration module 304 with respect to the positional relationship between the liquid feed pump 302 and the deaeration module 304 in the ink supply path 114. . However, the positional relationship between the liquid feed pump 302 and the deaeration module 304 may be reversed from that in FIG.

  FIG. 4 shows a modification of the configuration of the ink supply path 114. Except as described below, in FIG. 4, the configurations denoted by the same reference numerals as those in FIGS. 1 and 2 have the same or similar features as the configurations in FIGS.

  In the first ink flow path 122 of this modification, the deaeration module 304 is disposed upstream of the liquid feed pump 302. If comprised in this way, ink can be sent more stably, for example by sending ink with a liquid feeding means in the position near the inkjet head 102. FIG. Also in this case, for example, as in the configuration described with reference to FIGS. 1 to 3, stable supply of degassed ink and stable ejection of ink droplets by the inkjet head are achieved while suppressing the cost of the apparatus. It can be realized appropriately.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the description of the scope of claims that embodiments with such changes or improvements can be included in the technical scope of the present invention.

  The present invention can be suitably used for a printing system, for example.

DESCRIPTION OF SYMBOLS 10 ... Printing system, 12 ... Main part, 14 ... Ink supply part, 50 ... Medium, 102 ... Inkjet head, 104 ... Carriage, 106 ... Guide rail, 108. ..Media support unit, 110... Main scanning drive unit, 112 .. sub-scanning drive unit, 114... Ink supply path, 116... Control unit, 122. 2nd ink flow path, 202 ... Ink container, 204 ... Filter, 206 ... Valve, 302 ... Liquid feed pump (liquid feed means), 304 ... Deaeration module (degassing) 306 ... module suction unit, 308 ... valve, 310 ... subtank, 312 ... pressure damper (pressure adjustment unit), 314 ... overflow detection unit, 316 ... valve, 318 ... Ba Breakfast

Claims (12)

A printing system that performs printing by an inkjet method,
An inkjet head that ejects ink drops;
An ink container for storing ink;
A flow path for ink connecting the ink container and the inkjet head; a first ink flow path for flowing ink from the ink container toward the inkjet head;
A second ink channel that is an ink channel for flowing ink from either position in the first ink channel or the inkjet head to a side closer to the ink container;
The first ink flow path includes:
Liquid feeding means for sending ink in a direction from the ink container toward the inkjet head;
Degassing means for degassing the ink flowing through the first ink flow path;
A sub-tank that is a reservoir for storing ink deaerated by the deaerator;
A pressure adjusting unit that is disposed between the sub tank and the inkjet head and adjusts a supply pressure at which ink is supplied to the inkjet head;
The sub tank, the pressure adjusting unit, and the inkjet head are arranged in this order from the upstream side, which is the ink container side, to the downstream side, which is the inkjet head side, in the first ink flow path, and The pressure adjusting unit is disposed below the sub tank in the direction of gravity,
The sub-tank is at least partially open to the atmosphere so that at least a portion of the stored ink is in contact with the atmosphere, and sends the ink to the pressure adjustment unit due to a water head difference,
One end of the second ink flow path is connected to the sub tank, any position on the downstream side of the sub tank in the first ink flow path, or the inkjet head,
The other end of the second ink flow path is connected to any position between the ink container and the deaeration module, or to the ink container,
The printing system, wherein the second ink flow path causes ink to flow from the one end side to the other end side. The inkjet head is
Nozzles that eject ink drops;
An ink chamber for storing ink at a position adjacent to the nozzle;
The pressure adjusting unit adjusts the supply pressure of the ink to the ink jet head so that the pressure at which the ink is supplied to the ink chamber in the ink jet head is lower than atmospheric pressure. The printing system according to claim 1.   The printing system according to claim 1, wherein the pressure adjusting unit is a mechanical pressure damper.   The printing system according to claim 1, wherein the inkjet head is disposed below the pressure adjusting unit in a gravity direction. A carriage that holds the inkjet head facing a medium to be printed;
A main scanning drive unit that causes the inkjet head to perform a main scanning operation of ejecting ink droplets while moving in the main scanning direction by moving the carriage in a preset main scanning direction;
The sub tank and the pressure adjusting unit are held by the carriage together with the inkjet head,
5. The printing system according to claim 1, wherein during the main scanning operation, the sub tank and the pressure adjusting unit move in the main scanning direction together with the inkjet head.   The printing system according to claim 5, wherein the liquid feeding unit and the deaeration unit are disposed outside the carriage. The liquid feeding means is a tubing pump,
The printing system according to claim 1, wherein in the first ink path, the deaeration unit is disposed on the downstream side of the liquid feeding unit. The sub tank has a smaller volume than the ink container,
The printing system according to claim 1, wherein the other end of the second ink flow path is connected to a downstream side of the ink container in the first ink flow path. The second ink flow path has a valve for opening and closing the ink flow path,
9. The apparatus according to claim 1, wherein the valve is opened during a standby time when the printing operation by the inkjet head is not performed, and ink is allowed to flow through the second ink flow path. A printing system according to the above. A printing apparatus that performs printing by an ink jet method using ink supplied from an ink container,
An inkjet head that ejects ink drops;
A flow path for ink connecting the ink container and the inkjet head; a first ink flow path for flowing ink from the ink container toward the inkjet head;
A second ink channel that is an ink channel for flowing ink from either position in the first ink channel or the inkjet head to a side closer to the ink container;
The first ink flow path includes:
Liquid feeding means for sending ink in a direction from the ink container toward the inkjet head;
Degassing means for degassing the ink flowing through the first ink flow path;
A sub-tank that is a reservoir for storing ink deaerated by the deaerator;
A pressure adjusting unit that is disposed between the sub tank and the inkjet head and adjusts a supply pressure at which ink is supplied to the inkjet head;
The sub tank, the pressure adjusting unit, and the inkjet head are arranged in this order from the upstream side, which is the ink container side, to the downstream side, which is the inkjet head side, in the first ink flow path, and The pressure adjusting unit is disposed below the sub tank in the direction of gravity,
The sub-tank is at least partially open to the atmosphere so that at least a portion of the stored ink is in contact with the atmosphere, and sends the ink to the pressure adjustment unit due to a water head difference,
One end of the second ink flow path is connected to the sub tank, any position on the downstream side of the sub tank in the first ink flow path, or the inkjet head,
The other end of the second ink flow path is connected to any position between the ink container and the deaeration module, or to the ink container,
The printing apparatus, wherein the second ink flow path causes ink to flow from the one end side to the other end side. A printing method for performing printing by an inkjet method using ink supplied from an ink container,
Ink supply to the inkjet head that ejects ink droplets
A flow path for ink connecting the ink container and the inkjet head; a first ink flow path for flowing ink from the ink container toward the inkjet head;
Using a second ink channel, which is an ink channel for flowing ink from either position in the first ink channel or the inkjet head to a side closer to the ink container,
The first ink flow path includes:
Liquid feeding means for sending ink in a direction from the ink container toward the inkjet head;
Degassing means for degassing the ink flowing through the first ink flow path;
A sub-tank that is a reservoir for storing ink deaerated by the deaerator;
A pressure adjusting unit that is disposed between the sub tank and the inkjet head and adjusts a supply pressure at which ink is supplied to the inkjet head;
The sub tank, the pressure adjusting unit, and the inkjet head are arranged in this order from the upstream side, which is the ink container side, to the downstream side, which is the inkjet head side, in the first ink flow path, and The pressure adjusting unit is disposed below the sub tank in the direction of gravity,
The sub-tank is at least partially open to the atmosphere so that at least a portion of the stored ink is in contact with the atmosphere, and sends the ink to the pressure adjustment unit due to a water head difference,
One end of the second ink flow path is connected to the sub tank, any position on the downstream side of the sub tank in the first ink flow path, or the inkjet head,
The other end of the second ink flow path is connected to any position between the ink container and the deaeration module, or to the ink container,
The printing method, wherein the second ink flow path causes ink to flow from the one end side to the other end side. An ink supply method for supplying ink from an ink container that stores ink to an inkjet head that ejects ink droplets by an inkjet method,
A flow path for ink connecting the ink container and the inkjet head; a first ink flow path for flowing ink from the ink container toward the inkjet head;
Using a second ink flow path that is a flow path of ink that flows ink from either position in the first ink flow path or the inkjet head to a side closer to the ink container,
The first ink flow path includes:
Liquid feeding means for sending ink in a direction from the ink container toward the inkjet head;
Degassing means for degassing the ink flowing through the first ink flow path;
A sub-tank that is a reservoir for storing ink deaerated by the deaerator;
A pressure adjusting unit that is disposed between the sub tank and the inkjet head and adjusts a supply pressure at which ink is supplied to the inkjet head;
The sub tank, the pressure adjusting unit, and the inkjet head are arranged in this order from the upstream side, which is the ink container side, to the downstream side, which is the inkjet head side, in the first ink flow path, and The pressure adjusting unit is disposed below the sub tank in the direction of gravity,
The sub-tank is at least partially open to the atmosphere so that at least a portion of the stored ink is in contact with the atmosphere, and sends the ink to the pressure adjustment unit due to a water head difference,
One end of the second ink flow path is connected to the sub tank, any position on the downstream side of the sub tank in the first ink flow path, or the inkjet head,
The other end of the second ink flow path is connected to any position between the ink container and the deaeration module, or to the ink container,
The ink supply method, wherein the second ink flow path causes ink to flow from the one end side to the other end side.

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