Liquid spraying device

Abstract

To improve printing accuracy.SOLUTION: A liquid jet device includes a liquid jet head 10 which has a jet surface F1 having a first nozzle array NLA for jetting first ink, and a second nozzle array NLB for jetting second ink, and can hold the liquid jet head 10 in a first posture in which the jet surface F1 inclines with respect to a horizontal plane F0. Dynamic surface tension of the second ink is higher than dynamic surface tension of the first ink. The first nozzle array NLA is positioned above the second nozzle array NLB in a gravity direction G1 in the first posture.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection apparatus and a liquid ejection head. [Background technology]

[0002] In a recording head that ejects a plurality of types of ink, the ejection surface that ejects the ink may be inclined relative to the horizontal plane (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-34170 Summary of the Invention [Problem to be solved by the invention]

[0004] The dynamic surface tension of ink may differ depending on the type of ink. Conventional techniques do not take into consideration the relationship between the combined effect of the different dynamic surface tensions of multiple inks and the effect of an inclined ejection surface. [Means for solving the problem]

[0005] A liquid ejection device according to one aspect of the present invention includes a liquid ejection head having an ejection surface including a first nozzle row that ejects a first ink and a second nozzle row that ejects a second ink, and is capable of holding the liquid ejection head in a first position in which the ejection surface is inclined with respect to a horizontal plane. The dynamic surface tension of the second ink is greater than the dynamic surface tension of the first ink. In the first position, the first nozzle row is positioned higher than the second nozzle row in the direction of gravity.

[0006] A liquid ejection device according to one aspect of the present invention includes a first liquid ejection head having a first ejection surface including first nozzles for ejecting a first ink, and a second liquid ejection head having a second ejection surface including second nozzles for ejecting a second ink. The dynamic surface tension of the second ink is greater than the dynamic surface tension of the first ink. The first ejection surface is arranged so that the ejection direction of the first ink ejected from the first nozzles forms a first angle with the direction of gravity. The second ejection surface is arranged so that the ejection direction of the second ink ejected from the second nozzles forms a second angle that is greater than the first angle with the direction of gravity.

[0007] A liquid jet head according to one aspect of the present invention includes a first nozzle row that ejects a first ink, a second nozzle row that ejects a second ink, and a third nozzle row that ejects a third ink. The dynamic surface tension of the third ink is greater than the dynamic surface tension of the first ink and less than the dynamic surface tension of the second ink. The third nozzle row is located between the first nozzle row and the second nozzle row in the direction of gravity. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating a liquid ejecting apparatus according to a first embodiment. [Figure 2] FIG. 2 is a block diagram showing an ink flow path. [Figure 3] FIG. 2 is a bottom view showing a nozzle plate in which a nozzle row is formed. [Figure 4] 1 is a schematic diagram illustrating a liquid ejection head in an inclined position in which an ejection surface is inclined with respect to a horizontal plane. [Figure 5] FIG. 10 is a cross-sectional view showing a nozzle plate according to Comparative Example 1, illustrating a state in which droplets are jetted from the nozzles. [Figure 6] FIG. 10 is a cross-sectional view showing a nozzle plate according to Comparative Example 1, illustrating a state in which satellite droplets separated from a droplet are rising. [Figure 7] FIG. 2 is a cross-sectional view showing the nozzle plate according to the first embodiment, illustrating a state in which droplets are jetted from the nozzles. [Figure 8]FIG. 10 is a schematic diagram illustrating a liquid jet head of a liquid jet apparatus according to a second embodiment. [Figure 9] FIG. 10 is a schematic diagram illustrating a liquid jet head of a liquid jet apparatus according to a third embodiment. [Figure 10] FIG. 10 is a schematic diagram illustrating a liquid jet head of a liquid jet apparatus according to a fourth embodiment. [Figure 11] FIG. 10 is a schematic diagram illustrating a liquid ejecting apparatus according to a fifth embodiment. [Figure 12] 1 is a table showing ink components. [Figure 13] 10 is a bottom view illustrating an ejection surface of a liquid jet head according to a first modified example. FIG. [Figure 14] 10 is a bottom view illustrating an ejection surface of a liquid jet head according to a second modification. FIG. [Figure 15] 11 is a bottom view illustrating an ejection surface of a liquid jet head according to a third modification. FIG. [Figure 16] 10 is a bottom view illustrating an ejection surface of a liquid jet head according to a fourth modification. FIG. [Figure 17] FIG. 10 is a schematic diagram illustrating a liquid ejecting apparatus according to a second embodiment. [Figure 18] FIG. 2 is a schematic diagram illustrating the arrangement of a liquid jet head. [Figure 19] FIG. 2 is a schematic diagram illustrating the arrangement of a liquid jet head. [Figure 20] FIG. 2 is a schematic diagram illustrating the arrangement of a liquid jet head. [Figure 21] FIG. 2 is a schematic diagram illustrating the arrangement of a liquid jet head. [Figure 22] FIG. 2 is a schematic diagram illustrating the arrangement of a liquid jet head. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, in each drawing, the dimensions and scale of each part are appropriately different from those of the actual parts. Furthermore, since the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are applied, but the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description to the effect that the present invention is limited.

[0010] In the following description, the three mutually intersecting directions may be referred to as the X-axis direction, the Y-axis direction, and the Z-axis direction. The X-axis direction includes the X1 direction and the X2 direction, which are opposite directions. The X-axis direction is an example of a first direction. The Y-axis direction includes the Y1 direction and the Y2 direction, which are opposite directions. The Y-axis direction is an example of a second direction. The Z-axis direction includes the Z1 direction and the Z2 direction, which are opposite directions. The X-axis direction, the Y-axis direction, and the Z-axis direction are perpendicular to each other. Note that the X-axis direction, the Y-axis direction, and the Z-axis direction are directions based on the ejection surface F1 described later.

[0011] In addition, the downward direction of the gravity direction will be referred to as the gravity direction G1, and the direction perpendicular to both the gravity direction G1 and the X-axis direction will be referred to as the K-axis direction. Furthermore, the direction opposite to the gravity direction G1 will be referred to as the upward direction G2. The K-axis direction includes the K1 direction and the K2 direction, which are opposite to each other. The K-axis direction is an example of a third direction. The K-axis direction is an example of a horizontal direction. The horizontal direction is a direction perpendicular to the gravity direction G1. The third direction is a direction perpendicular to both the first direction and the gravity direction G1.

[0012] FIG. 1 is a schematic diagram showing a liquid ejection device 1 according to a first embodiment. FIG. 2 is a block diagram showing an ink flow path. The liquid ejection device 1 is an inkjet printing device that ejects ink, an example of a "liquid," as droplets onto a medium PA. The liquid ejection device 1 is a so-called line-type printing device in which multiple nozzles that eject ink are distributed across the entire range in the width direction of the medium PA. The medium PA is typically printing paper. Note that the medium PA is not limited to printing paper and may be a printing target made of any material, such as a resin film or fabric.

[0013] The liquid ejection device 1 includes a liquid ejection head 10 having an ejection surface F1 that is inclined with respect to a horizontal plane F0. The liquid ejection device 1 includes a plurality of liquid containers 2, a control unit 3, a medium transport mechanism 4, an ink supply unit 5, and the liquid ejection heads 10. The liquid ejection device 1 may include one liquid ejection head 10 or multiple liquid ejection heads 10. The liquid ejection device 1 of this embodiment includes one liquid ejection head 10. When multiple liquid ejection heads 10 are included, the multiple liquid ejection heads 10 are arranged in the X-axis direction to form a line head.

[0014] The control unit 3 controls the operation of each element of the liquid ejection device 1. The control unit 3 includes, for example, a processing circuit such as a CPU or FPGA, and a storage circuit such as a semiconductor memory. Various programs and data are stored in the storage circuit. The processing circuit executes the programs and uses the data as appropriate to realize various controls. CPU is an abbreviation for Central Processing Unit. FPGA is an abbreviation for Field Programmable Gate Array.

[0015] The medium transport mechanism 4 is controlled by the control unit 3 and transports the medium PA in a transport direction DM. The transport direction DM is the transport direction of the medium PA at a position facing the ejection surface F1, and is parallel or approximately parallel to the Y-axis direction. The medium transport mechanism 4 includes a transport roller that is long along the width direction of the medium PA and a motor that rotates the transport roller. Note that the medium transport mechanism 4 is not limited to a configuration that uses a transport roller, and may be configured, for example, to use a drum or endless belt that transports the medium PA while adsorbed to its outer peripheral surface by electrostatic force or the like.

[0016] The liquid ejecting device 1 is formed with a medium transport path 4a for transporting the medium PA. The medium transport path 4a is a path that leads from the paper feed unit 4b to the paper discharge unit 4c. The medium transport mechanism 4 transports the medium PA along the medium transport path 4a. The paper feed unit 4b and the paper discharge unit 4c include trays that can store the medium PA.

[0017] The liquid container 2 stores ink. Specific examples of the liquid container 2 include a cartridge that is detachable from the liquid ejecting device 1, a bag-shaped ink pack made of flexible film, and an ink tank that can be refilled with ink. The type of ink stored in the liquid container 2 is arbitrary.

[0018] The liquid container 2 includes liquid containers 2A, 2B, 2C, and 2D. The liquid container 2A stores a first ink. The liquid container 2B stores a second ink. The liquid container 2C stores a third ink. The liquid container 2D stores a fourth ink. For example, the first ink, second ink, third ink, and fourth ink are inks of different colors. The first ink, second ink, third ink, and fourth ink each have a different dynamic surface tension. The dynamic surface tension of the second ink is greater than that of the first ink. The dynamic surface tension of the third ink is greater than that of the first ink and less than that of the second ink. The dynamic surface tension of the fourth ink is less than that of the second ink and greater than that of the third ink. The components of each type of ink and the measurement of dynamic surface tension will be described later.

[0019] The difference between the dynamic surface tension of the first ink and the dynamic surface tension of the second ink is 1.0 mN / m or more. In the dynamic surface tension measurements described below, when the lifetime is set to 10 msec, the dynamic surface tension of the second ink is greater than that of the first ink. When the lifetime is set to 10 msec, the dynamic surface tensions of the first to fourth inks are arranged in order from highest to lowest, in the order of the dynamic surface tension of the second ink, the dynamic surface tension of the fourth ink, the dynamic surface tension of the third ink, and the dynamic surface tension of the first ink.

[0020] The ink supply unit 5 has ink flow paths 6 and 7 that supply ink from the liquid container 2 to the liquid jet head 10, and a pressure adjustment unit 8 that adjusts the pressure of the ink inside the liquid jet head 10. The ink flow path 6 includes a flow path from the liquid container 2 to the pressure adjustment unit 8. The ink flow path 7 includes a flow path from the pressure adjustment unit 8 to the liquid jet head 10. The ink flow path 7 includes a flow path formed inside the liquid jet head 10. The ink flow paths 6 and 7 are formed by, for example, piping or tubes. The ink flow paths 6 and 7 include, for example, flow path members in which grooves, recesses, through holes, etc. are formed, as well as piping, tubes, etc.

[0021] The pressure adjustment unit 8 adjusts the pressure of the ink supplied to the liquid jet head 10 so that a predetermined pressure acts on the nozzles N. The pressure adjustment unit 8 may also adjust the pressure of the ink supplied to the liquid jet head 10 using a sub-tank that temporarily stores ink. The pressure adjustment unit 8 may adjust the pressure of the ink in the liquid jet head 10 by keeping the amount of ink stored in the sub-tank constant.

[0022] The pressure adjustment unit 8 includes pressure adjustment units 8A, 8B, 8C, and 8D. The pressure adjustment unit 8A is connected to the liquid container 2A and adjusts the pressure of the first ink. The pressure adjustment unit 8B is connected to the liquid container 2B and adjusts the pressure of the second ink. The pressure adjustment unit 8C is connected to the liquid container 2C and adjusts the pressure of the third ink. The pressure adjustment unit 8D is connected to the liquid container 2D and adjusts the pressure of the fourth ink.

[0023] 3 is a bottom view showing a nozzle plate 11 in which a nozzle row NL is formed. The liquid ejection head 10 includes the nozzle plate 11 having a plurality of nozzle rows NL. The nozzle row NL includes a plurality of nozzles N that eject ink. Of the surfaces of the nozzle plate 11, the surface that faces the medium PA is the ejection surface F1 that ejects ink. A plurality of nozzles N are formed in the ejection surface F1. The ejection surface F1 is disposed at a distance from the medium PA.

[0024] The multiple nozzle arrays NL include nozzle arrays NLA, NLB, NLC, and NLD. The nozzle array NLA includes multiple nozzles N that eject a first ink. The nozzle array NLB includes multiple nozzles N that eject a second ink. The nozzle array NLC includes multiple nozzles N that eject a third ink. The nozzle array NLD includes multiple nozzles N that eject a fourth ink. Note that when there is no need to distinguish between the nozzle arrays NLA, NLB, NLC, and NLD, they may be referred to as the nozzle array NL.

[0025] The nozzle row NL includes a plurality of nozzles N lined up in the X-axis direction. The nozzles N are through-holes that penetrate the nozzle plate 11 in the thickness direction. The thickness direction of the nozzle plate 11 is along the Z-axis direction. The nozzle rows NLA, NLB, NLC, and NLD are arranged at different positions from each other in the Y-axis direction.

[0026] The nozzle arrays NLA, NLC, NLD, and NLB are arranged in this order in the Y1 direction. The nozzle arrays NLA, NLC, NLD, and NLB are spaced apart from one another in the Y-axis direction. The nozzle array NLC is arranged between the nozzle arrays NLA and NLB in the Y-axis direction. The nozzle array NLD is arranged between the nozzle arrays NLC and NLB in the Y-axis direction.

[0027] When viewed in the Y-axis direction, the nozzle arrays NLA, NLC, NLD, and NLB at least partially overlap. In this embodiment, when viewed in the Y-axis direction, the nozzle arrays NLA, NLC, NLD, and NLB completely overlap.

[0028] 1, the liquid jet head 10 is held, for example, in an inclined position relative to the housing 1a of the liquid jet device 1. Note that "the liquid jet head 10 is held relative to the housing 1a of the liquid jet device 1" includes both a case where the liquid jet head 10 is directly fixed and held relative to the housing 1a, and a case where the liquid jet head 10 is indirectly held relative to the housing 1a via a member different from the housing 1a. The liquid jet device 1 can hold the liquid jet head 10 in an inclined position in which the ejection surface F1 is inclined relative to a horizontal plane F0.

[0029] FIG. 4 is a schematic diagram showing the liquid jet head 10 in an inclined posture in which the ejection surface F1 is inclined with respect to the horizontal plane F0. As shown in FIG. 4, the ejection surface F1 of the liquid jet head 10 is inclined with respect to the horizontal plane F0 at an inclination angle θ1. The inclination angle θ1 is, for example, an acute angle less than 90 degrees. The inclination angle θ1 may also be an obtuse angle greater than 90 degrees. The inclination angle θ1 may also be 90 degrees. The inclination referred to here includes 90 degrees. The inclined posture of the liquid jet head 10 in which the ejection surface F1 is inclined with respect to the horizontal plane F0 at an inclination angle θ1 is an example of a first posture.

[0030] 4, the multiple nozzle arrays NL are arranged at different heights in the direction of gravity G1. The nozzle array NLA is arranged at a height position HA, and the nozzle array NLB is arranged at a height position HB. The height position HA is located higher than the height position HB. In other words, the nozzle array NLA, which ejects the first ink having a smaller dynamic surface tension, is located higher than the nozzle array NLB, which ejects the second ink having a larger dynamic surface tension.

[0031] The nozzle row NLC is disposed at a height position HC. The height position HC is lower than the height position HA and higher than the height position HB. When the liquid ejecting head 10 is in an inclined position, the nozzle row NLC is located lower than the nozzle row NLA and higher than the nozzle row NLB. In other words, the nozzle row NLC, which ejects the third ink, which has the second smallest dynamic surface tension among the first ink, second ink, and third ink, is disposed between the nozzle row NLA and the nozzle row NLB in the direction of gravity G1.

[0032] The nozzle row NLD is disposed at a height position HD. The height position HD is lower than the height position HC and higher than the height position HB. When the liquid ejecting head 10 is in an inclined position, the nozzle row NLD is located lower than the nozzle row NLC and higher than the nozzle row NLB. In other words, the nozzle row NLD, which ejects the fourth ink, which has the second smallest dynamic surface tension among the second ink, the third ink, and the fourth ink, is disposed between the nozzle row NLC and the nozzle row NLB in the direction of gravity G1.

[0033] As shown in FIG. 4, when viewed in the X-axis direction, the nozzle arrays NLA, NLC, NLD, and NLB are arranged at intervals from one another.

[0034] When a plurality of nozzle rows NL are compared, the nozzle row NL that ejects ink with a smaller dynamic surface tension is positioned above the nozzle row NL that ejects ink with a larger dynamic surface tension.

[0035] Next, the behavior of droplets 101, 102 ejected from nozzle N and satellite droplets 101a separated from the droplet 101 will be described with reference to FIGS. 5 to 7. Here, nozzle plates 11, 111 that eject two types of ink with different dynamic surface tensions will be described as examples. FIGS. 5 and 6 show the nozzle plate 111 according to Comparative Example 1, and FIG. 7 shows the nozzle plate 11 according to Example 1. In the nozzle plate 111 according to Comparative Example 1, the nozzle row NLB that ejects the second ink, which has a higher dynamic surface tension, is positioned above the nozzle row NLA that ejects the first ink, which has a lower dynamic surface tension. In the nozzle plate 11 according to Example 1, the nozzle row NLA that ejects the first ink is positioned above the nozzle row NLB that ejects the second ink, which is the opposite of Comparative Example 1.

[0036] FIG. 5 is a cross-sectional view of a nozzle plate 111 according to Comparative Example 1, showing a state in which droplets are ejected from a nozzle. A droplet 102 of the second ink is ejected from a nozzle NB. A droplet 101 of the first ink is ejected from a nozzle NA. The dynamic surface tension of the first ink is smaller than that of the second ink, and satellite droplets 101a are more likely to be generated than with the second ink. The volume of the satellite droplet 101a is smaller than the volume of the droplet 101. The mass of the satellite droplet 101a is smaller than the mass of the droplet 101. Studies by the present inventors have found that the satellite droplet 101a rises in the upward direction G2 after being ejected from the nozzle N.

[0037] FIG. 6 is a cross-sectional view of a nozzle plate 111 according to Comparative Example 1, illustrating a state in which satellite droplets separated from a droplet 101 are rising. As shown in FIG. 6, when the satellite droplets 101a rise, they may adhere to the nozzles NB of the ejection surface F1. If the satellite droplets 101a adhere to the nozzles NB, the second ink in the nozzles NB and the first ink, which are the satellite droplets 101a, may mix together, potentially degrading print quality. Furthermore, as the satellite droplets 101a rise, they may adhere to the ejection surface F1 around the nozzles NB, causing an abnormality in the meniscus of the second ink formed in the nozzles NB, potentially resulting in ejection failure.

[0038] FIG. 7 is a cross-sectional view showing the nozzle plate 11 according to the first embodiment, illustrating a state in which droplets 101 and 102 are ejected from the nozzles NA and NB. In the state shown in FIG. 7, a satellite droplet 101a separated from the droplet 101 is positioned above the droplet 101. The nozzle NB and the droplet 102 are not present above the satellite droplet 101a. Therefore, there is no risk of the satellite droplet 101a adhering to the droplet 102. In this way, the nozzle array NLA, which ejects the first ink having a smaller dynamic surface tension, is positioned above the nozzle array NLB in the direction of gravity G1, and therefore, in the first embodiment, the risk of color mixing between the first ink and the second ink and abnormalities occurring in the meniscus of the first ink in the nozzle N of the nozzle array NLA is reduced.

[0039] 4, the nozzle arrays NLA, NLB, NLC, and NLD are arranged according to the dynamic surface tension of the ink. The nozzle array NLA, which ejects the first ink, which has the smallest dynamic surface tension, is arranged at a higher position in the direction of gravity G1 than the other nozzle arrays NLB, NLC, and NLD. In this way, because the nozzle array NLA, which ejects the first ink, which is most likely to produce satellite droplets, is arranged at a higher position, it is possible to prevent the first ink from mixing with the other second, third, and fourth inks and to prevent abnormalities from occurring in the meniscus of the first ink in the nozzles N of the nozzle array NLA.

[0040] In the liquid ejection head 10, the nozzle row NLB that ejects the second ink, which has the highest dynamic surface tension, is disposed at a lower position in the direction of gravity G1 than the other nozzle rows NLA, NLC, and NLD. In this way, because the nozzle row NLB that ejects the second ink, which is least likely to produce satellite droplets, is disposed at a lower position, the second ink is prevented from mixing with the other first ink, third ink, and fourth ink, and abnormalities are prevented from occurring in the meniscus of the first ink, third ink, and fourth ink in the nozzles N of the nozzle rows NLA, NLC, and NLD.

[0041] In the liquid ejection head 10, the nozzle row NL that ejects the first ink, which has a smaller dynamic surface tension, is positioned higher in the direction of gravity G1 than the nozzle row NL that ejects the second ink, which has a larger dynamic surface tension, and therefore mixing of different types of ink and abnormalities in the meniscus in the nozzles N are suppressed. As a result, it is possible to improve the printing accuracy of the liquid ejection device 1. Compared to the configuration of Comparative Example 1, in which the nozzle row NL that ejects the second ink, which has a larger dynamic surface tension, is positioned higher than the nozzle row NL that ejects the first ink, which has a smaller dynamic surface tension, the liquid ejection head 10 is less likely to cause mixing of multiple inks and abnormalities in the meniscus of the ink in the nozzles N.

[0042] In the liquid ejection head 10, the nozzle row NLC is located between the nozzle row NLA and the nozzle row NLB in the direction of gravity G1. The dynamic surface tension of the third ink ejected from the nozzle row NLC is greater than the dynamic surface tension of the first ink and less than the dynamic surface tension of the second ink. Satellite droplets separated from the first ink are unlikely to adhere to the third ink below. Because there is little risk of satellite droplets being generated from the second ink, there is little chance that the second ink will adhere to the third ink or that abnormalities will occur in the meniscus of the third ink in the nozzles N of the nozzle row NLC.

[0043] In the liquid ejection head 10, the nozzle row NLD is located between the nozzle row NLC and the nozzle row NLB in the direction of gravity G1. The dynamic surface tension of the fourth ink ejected from the nozzle row NLD is greater than the dynamic surface tension of the third ink and less than the dynamic surface tension of the second ink. Satellite droplets separated from the second ink are unlikely to adhere to the fourth ink above. Because there is little risk of satellite droplets being generated from the second ink, there is little chance that the second ink will adhere to the fourth ink or that an abnormality will occur in the meniscus inside the nozzle N of the nozzle row NLD.

[0044] Next, a description will be given of a change in posture of the liquid jet head 10 according to the second embodiment with reference to Fig. 8. Fig. 8 is a schematic diagram showing the liquid jet head 10 according to the second embodiment. In Fig. 8, the liquid jet head 10 in a first posture P1 in which the ejection surface F1 is inclined with respect to the horizontal plane F0 is shown by a solid line, and the liquid jet head 10 in a second posture P2 in which the ejection surface F1 is disposed along the horizontal plane F0 is shown by a dashed line. The liquid jet head 10 can rotate about a rotation axis S1 extending in the X-axis direction.

[0045] The attitude of the liquid jet head 10 is changeable to a plurality of attitudes including a first attitude P1 and a second attitude P2. The liquid jet device 1 according to the second embodiment has an attitude change mechanism 13 that changes the attitude of the liquid jet head 10. The attitude change mechanism 13 includes a bearing 14 that holds a rotation shaft S1 that extends in the X-axis direction, and a drive mechanism 15 that rotates the rotation shaft S1. The bearing 14 rotatably supports the rotation shaft S1. The drive mechanism 15 includes, for example, a motor.

[0046] In FIG. 8, the imaginary lines L1 and L2 are indicated by two-dot chain lines. The imaginary line L1 is an imaginary straight line that passes through the center C1 between the nozzle row NLA and the nozzle row NLB and extends in a direction perpendicular to the ejection surface F1 in the first posture P1. The imaginary line L1 is an example of a "first imaginary line." The imaginary line L1 extends in the Z-axis direction when viewed in the X-axis direction. When the liquid jet head 10 is in the first posture P1, the rotation axis S1 is located closer to the nozzle row NLA than the imaginary line L1. In other words, when the liquid jet head 10 is in the first posture P1, the rotation axis S1 is located closer to the nozzle row NLA in the Y-axis direction than the imaginary line L1.

[0047] The imaginary line L2 is an imaginary straight line that passes through the center C1 between the nozzle row NLA and the nozzle row NLB and extends in a direction perpendicular to the ejection surface F1 in the second attitude P2. The imaginary line L2 extends in the Z-axis direction when viewed in the X-axis direction. In FIG. 8, arrows indicating the X-axis, Y-axis, and Z-axis directions in the second attitude P2 are indicated by dashed lines. The first attitude P1 and the second attitude P2 are shifted by an inclination angle θ1 when viewed in the X-axis direction. When the liquid jet head 10 is in the second attitude P2, the rotation axis S1 is located closer to the nozzle row NLB when viewed from the imaginary line L2. In other words, when the liquid jet head 10 is in the second attitude P2, the rotation axis S1 is located closer to the nozzle row NLA in the Y-axis direction than the imaginary line L2.

[0048] In addition, in the first posture P1 and the second posture P2, the rotation axis S1 may be located at the same position or at different positions. When the posture of the liquid jet head 10 changes from the first posture P1 to the second posture P2, the liquid jet head 10 may move linearly. The liquid jet device 1 can linearly move the bearing 14 that holds the rotation axis S1. For example, linear movement can be achieved by a rack and pinion. The liquid jet head 10 can also be linearly moved by using other mechanisms such as a ball screw, a guide groove, an actuator, or a belt mechanism.

[0049] Next, the centrifugal force acting on the meniscus when the liquid jet head 10 is rotated will be described. When the liquid jet head 10 is rotated about the rotation axis S1, a centrifugal force acts on the meniscus in the multiple nozzle arrays NL. The rotation radius RB from the rotation axis S1 to the nozzle array NLB is larger than the rotation radius RA from the rotation axis S1 to the nozzle array NLA. When the liquid jet head 10 is rotated, the magnitude of the centrifugal force acting on the meniscus of the nozzle array NLA is different from the magnitude of the centrifugal force acting on the meniscus of the nozzle array NLB. When the liquid jet head 10 is rotated, the magnitude of the centrifugal force acting on the meniscus of the nozzle array NLB is larger than the magnitude of the centrifugal force acting on the meniscus of the nozzle array NLA.

[0050] The centrifugal force acting immediately after the liquid ejection head 10 starts to rotate acts to move the meniscus inside the nozzle N out of the nozzle. In other words, this centrifugal force acts to move the meniscus in a direction away from the rotation axis S1. The inertial force caused by this centrifugal force is a force that moves the meniscus into the nozzle N. In other words, the inertial force caused by the centrifugal force is a force that acts on the meniscus in a direction approaching the rotation axis S1. Such centrifugal force and the inertial force caused by the centrifugal force may cause the meniscus to fly out of the nozzle N or the meniscus to recess, drawing air bubbles into the nozzle N.

[0051] When the dynamic surface tensions of the inks are the same, the meniscus is more likely to collapse in the nozzle row NLB, which has a greater centrifugal force, than in the nozzle row NLA, which has a smaller centrifugal force. In the liquid ejection head 10, a first ink, which has a smaller dynamic surface tension, is supplied to the nozzle row NLA, and a second ink, which has a larger dynamic surface tension, is supplied to the nozzle row NLB. The first ink is supplied to the nozzle row NLA, which has a smaller centrifugal force, and the second ink is supplied to the nozzle row NLB, which has a larger rotational moment. As a result, the second ink, which has a larger dynamic surface tension, is supplied to the nozzle, which has a larger centrifugal force, thereby preventing the meniscus from collapsing.

[0052] In the liquid ejection head 10, of the multiple types of ink, the ink with the higher dynamic surface tension is supplied to the nozzle row NL with the higher centrifugal force, and the ink with the lower dynamic surface tension is supplied to the nozzle row NL with the lower centrifugal force, thereby suppressing the collapse of the ink meniscus in the nozzle N.

[0053] In the liquid ejecting head 10, by suppressing the collapse of the meniscus, it is possible to suppress the intrusion of air bubbles into the nozzles N of the nozzle array NLA, or to suppress the leakage of ink from the nozzles N of the nozzle array NLA.

[0054] Note that the liquid jet head 10 according to the second embodiment includes a plurality of nozzle rows NL each extending in the X-axis direction, but may also include a nozzle row NL extending in a direction intersecting the X-axis when the ejection surface F1 is viewed in a plan view toward the Z-axis direction. In this case, the rotation radius from the rotation axis S1 to the nozzle row NL may be the distance between the rotation axis S1 and the nozzle N that is farthest from the rotation axis S1 among the plurality of nozzles N that constitute the nozzle row NL when viewed in the X-axis direction.

[0055] Next, a liquid jet head 10 according to a third embodiment will be described with reference to FIG. 9. FIG. 9 is a schematic diagram showing the liquid jet head 10 of the liquid jet device 1 according to the third embodiment and a cap 22 that covers the ejection surface F1 of the liquid jet head 10. The liquid jet device 1 is capable of performing a maintenance operation. The liquid jet device 1 performs the maintenance operation when the liquid jet head 10 is in the second attitude P2. The liquid jet device 1 performs a printing operation (recording operation) when the liquid jet head 10 is in the first attitude P1 shown in FIG. 8, and performs the maintenance operation when the liquid jet device 1 is in the second attitude P2 shown in FIG. 9. In other words, the first attitude P1 is an example of a "recording attitude," and the second attitude P2 is an example of a "maintenance attitude." The printing operation is an example of a recording operation. The "recording operation" refers to ejecting ink from the nozzles N and depositing the ink on a medium to record characters, images, etc.

[0056] The liquid ejecting device 1 includes a cap 22, a pipe 23, and a pump 24 that are used for maintenance operations. The cap 22 covers the ejection surface F1 of the liquid ejecting head 10. The cap 22 is arranged to cover the openings of the nozzles N of the multiple nozzle rows NL. The cap 22 is formed with a space 22a that receives ink ejected from the nozzles N.

[0057] A pipe 23 is connected to the cap 22. The pipe 23 is a pipe that discharges ink present in the space 22a of the cap 22. A pump 24 is connected to the pipe 23. By driving the pump 24, the ink inside the cap 22 can be sucked and discharged outside the cap 22.

[0058] Maintenance operations for the liquid ejection device 1 include a flushing process, a suction cleaning process, and a pressure cleaning process. These maintenance operations are performed when the liquid ejection head 10 is in the second attitude P2. In the flushing process, an actuator of the liquid ejection head 10 is used to apply pressure fluctuations to pressure chambers communicating with the nozzles N, thereby ejecting ink that does not contribute to the recording operation from the nozzles N. In the suction cleaning process, for example, a pump 24 is used to suction ink from the nozzles N. In addition, in the pressure cleaning process, a pump (not shown) or the like may be used to pressurize the ink flow paths in the liquid ejection head 10 from upstream of the pressure chambers, thereby discharging ink from the nozzles N.

[0059] In this way, in the liquid ejection device 1, unnecessary ink in the nozzles N can be discharged to the outside of the liquid ejection head 10 by performing a maintenance process. When the liquid ejection head 10 is in the second attitude P2, the ejection surface F1 is parallel to the horizontal plane F0. In the liquid ejection device 1, a maintenance operation can be performed in this second attitude P2, so that the amount of ink remaining in the cap 22 can be reduced during idle suction, in which the pump 24 is driven with the space inside the cap 22 in communication with the atmosphere. For example, when the liquid ejection head 10 is in the first attitude P1, the cap 22 is tilted, so ink remains in the corner portions 22c inside the cap 22. On the other hand, in this embodiment, the maintenance operation is performed with the bottom surface 22b of the cap 22 positioned along the horizontal plane F0, so that the amount of ink remaining in the cap 22 can be reduced.

[0060] In the liquid ejection device 1, the attitude of the liquid ejection head 10 can be changed from a first attitude P1 to a second attitude P2. As described above, when the liquid ejection head 10 rotates around the rotation axis S1, centrifugal force and the inertial force resulting from this centrifugal force act on the meniscus of the ink in the nozzle row NL, which may cause the meniscus to collapse. In the liquid ejection device 1, the second ink, which has the greatest dynamic surface tension among the multiple types of ink, is supplied to the nozzle row NLB, where the centrifugal force and the inertial force resulting from this centrifugal force are greatest, thereby reducing the possibility of the meniscus collapsing. By preventing the meniscus from collapsing, the intrusion of air bubbles into the nozzles N of the liquid ejection head 10 is prevented, or the leakage of ink from the nozzles N of the nozzle row NLA is prevented.

[0061] Next, a maintenance operation performed when the liquid jet head 10 according to the fourth embodiment is in a tilted state will be described with reference to Fig. 10. As shown in Fig. 10, the maintenance operation may be performed when the liquid jet head 10 is in a first posture P1 in which it is tilted.

[0062] The liquid ejection device 1 equipped with the liquid ejection head 10, in the first attitude P1, executes a cleaning operation in which the nozzle array NLA ejects a first ink onto the ejection surface F1, and the second nozzle array NLB ejects a second ink onto the ejection surface F1. The cleaning operation is one of the maintenance operations. Discharging ink onto the ejection surface F1 means, for example, breaking down the ink meniscus in the nozzle N, causing the ink to leak from the nozzle N. The ink leaking from the nozzle N flows along the ejection surface F1.

[0063] Here, when ink with high dynamic surface tension is ejected onto the ejection surface F1, the ink tends to remain on the ejection surface F1, while when ink with low dynamic surface tension is ejected onto the ejection surface F1, the ink tends to move along the ejection surface F1. The first ink, which has low dynamic surface tension, leaks from the nozzle row NLA, which is located at the highest position among the multiple nozzle rows NL. This allows the ink adhering to the ejection surface F1 to be washed away. Because the first ink, which flows most easily along the ejection surface F1, is ejected from a higher position, the second ink, which is ejected from a lower position and tends to remain on the ejection surface F1, can be washed away. As a result, the ink remaining on the ejection surface F1 can be reduced. If ink remains on the ejection surface F1, the ink adhering to the ejection surface F1 may flow downward and mix with the ink ejected from the nozzle N below. However, in the liquid ejection device 1, the ink remaining on the ejection surface F1 is reduced, thereby suppressing a deterioration in print quality.

[0064] In this cleaning operation, a pressure cleaning process or a suction cleaning process may be performed.

[0065] Next, a liquid ejection device 1 according to a fifth embodiment will be described with reference to FIG. 11. In the fifth embodiment, the influence of centrifugal force acting on the nozzle row NL of the liquid ejection head 10 when the liquid ejection device 1 is placed on a floor surface 26 will be described. The liquid ejection head 10 of the liquid ejection device 1 is disposed at an angle with respect to a horizontal plane F0. The liquid ejection device 1 includes a housing 1a that accommodates the liquid ejection head 10. The liquid ejection head 10 is held relative to the housing 1a. Legs 1c and 1d are provided on the bottom of the housing 1a. The legs 1c and 1d are disposed on the floor surface 26. The floor surface 26 is, for example, along the horizontal plane F0.

[0066] In FIG. 11, the K-axis direction, which is perpendicular to the direction of gravity G1 when viewed in the X-axis direction, is indicated by an arrow. The K-axis direction is along the left-right direction in FIG. 11. The legs 1c and 1d are spaced apart in the K-axis direction. For example, the K-axis direction is along the longitudinal direction of the housing 1a when the liquid ejecting device 1 is viewed in the direction of gravity G1. Note that the legs 1c and 1d may also be spaced apart in other directions.

[0067] Leg 1c includes contact Q1, and leg 1d includes contact Q2. Contact Q1 is an example of a first contact, and contact Q2 is an example of a second contact. Contacts Q1 and Q2 are portions that come into contact with floor surface 26 when housing 1a is placed on floor surface 26. Contact Q1 is located closer to one end 1e of housing 1a in the K-axis direction. Contact Q2 is located closer to the other end 1f of housing 1a in the K-axis direction. One end 1e of housing 1a is the end of housing 1a in the K1 direction. The other end 1f of housing 1a is the end of housing 1a in the K2 direction.

[0068] The center of gravity G of the liquid ejection device 1 is located between the tangent point Q1 and the tangent point Q2 in the K-axis direction, closer to the tangent point Q1 than the tangent point Q2. When viewed in the X-axis direction, the distance DR between the tangent point Q1 and the nozzle row NLB is longer than the distance UR between the tangent point Q1 and the nozzle row NLA. When viewed in the X-axis direction, the distance UL between the tangent point Q2 and the nozzle row NLA is longer than the distance DL between the tangent point Q2 and the nozzle row NLB. The position of the nozzle row NL is, for example, the center position of the opening of the nozzle N on the ejection surface F1.

[0069] 11, the distance DR is longer than the distance UR. In the first posture of the liquid jet head 10, the distance UL is longer than the distance DR.

[0070] For example, when moving the liquid ejection device 1, it is assumed that multiple workers carry the liquid ejection device 1 and eventually place the liquid ejection device 1 on the floor surface 26. For example, two workers separated in the K-axis direction can hold the liquid ejection device 1 from both sides. When placing the liquid ejection device 1 on the floor surface 26, one worker closer to the one end 1e first touches the leg 1c to the floor surface 26, and then the other worker closer to the other end 1f touches the leg 1d to the floor surface 26. When the leg 1c first touches the floor surface 26, the liquid ejection device 1 rotates counterclockwise R1 as viewed in the X-axis direction, with the contact point Q1 as the fulcrum. In this case, because the distance DR is longer than the distance UR, a greater centrifugal force acts on the nozzle row NLB than on the nozzle row NLA.

[0071] As described above, when the liquid ejection device 1 is placed on the floor surface 26, centrifugal forces and inertial forces resulting from these centrifugal forces are generated in the nozzle arrays NLA and NLB of different magnitudes depending on the distances UR and DR from the contact point Q1. In the liquid ejection device 1, the first ink is supplied to the nozzle array NLA, and the second ink is supplied to the nozzle array NLB. The second ink, which has a higher dynamic surface tension, is supplied to the nozzle array NLB, which experiences a larger centrifugal force and inertial force, and the first ink, which has a lower dynamic surface tension, is supplied to the nozzle array NLA, which experiences a smaller centrifugal force and inertial force. This reduces the risk of the meniscus of the second ink in the nozzle array NLB collapsing in the liquid ejection head 10. In other words, the risk of the meniscus collapsing is lower when the second ink is supplied to the nozzle array NLB than when the first ink is supplied to the nozzle array NLB.

[0072] In the case of the liquid ejecting device 1, the center of gravity G of the liquid ejecting device 1 is located closer to leg 1c than to leg 1d in the K-axis direction, so there is a high possibility that the worker will bring leg 1c into contact with the floor surface 26 before leg 1d. In the liquid ejecting device 1, as described above, the first ink is supplied to the nozzle array NLA, so the risk of the meniscus in the nozzle array NLA collapsing is reduced.

[0073] When moving the liquid ejection device 1, multiple workers may hold the liquid ejection device 1 at intervals in the X-axis direction. Because the nozzle array NLA is located higher than the nozzle array NLB in the direction of gravity G1, the distance between the nozzle array NLB and the point of contact between the housing 1a and the floor surface 26 that is closest to the X1 direction is longer than the distance between the nozzle array NLA. Similarly, the distance between the nozzle array NLB and the point of contact between the housing 1a and the floor surface 26 that is closest to the X2 direction is longer than the distance between the nozzle array NLA and the point of contact. Therefore, whether the end of the housing 1a in the X1 direction or the end of the housing 1a in the X2 direction is lowered first, collapse of the meniscus can be suppressed because the first ink is assigned to the nozzle array NLA.

[0074] Note that the liquid jet head 10 according to the fifth embodiment includes a plurality of nozzle rows NL each extending in the X-axis direction, but may also include a nozzle row NL extending in a direction intersecting the X-axis when the ejection surface F1 is viewed in a plan view in the Z-axis direction. In this case, the distance from the tangent point to the nozzle row NL may be the distance between the tangent point and the nozzle N farthest from the tangent point among the plurality of nozzles N constituting the nozzle row NL when viewed in the X-axis direction.

[0075] Next, a method for measuring the dynamic surface tension of ink and the properties of the ink will be described. The dynamic surface tension of ink can be determined, for example, by the maximum bubble pressure method. Other methods for measuring dynamic surface tension may also be used, such as the hanging drop method, the Wilhelmy method, and the ring method. In the maximum bubble pressure method, the tip of a capillary tube is immersed in ink, and the maximum pressure required to release bubbles from the capillary tube is measured. In this maximum bubble pressure method, bubbles are continuously generated at the tip of the capillary tube, and the maximum pressure is measured.

[0076] In this maximum bubble pressure method, the lifetime is the time from when a new bubble appears at the tip of the capillary tube during measurement of the maximum pressure until the maximum bubble pressure is reached. The maximum bubble pressure is reached when the radius of curvature of the bubble is equal to the radius of the capillary tube. The dynamic surface tension of the ink is the surface tension of the ink when the ink is in motion. The dynamic surface tension of the ink can be adjusted, for example, by changing the type and content of surfactants, water-soluble organic solvents, resins, etc. contained in the ink.

[0077] The properties of the ink will be explained below, but unless otherwise specified, the amounts of components are expressed as "parts" and "%" by weight. Figure 12 is a table showing the components of the ink.

[0078] Pigment Dispersion Liquid 1 will be described. A styrene-ethyl acrylate-acrylic acid copolymer (resin dispersant) with an acid value of 150 mgKOH / g and a weight-average molecular weight of 8,000 was prepared. The prepared resin dispersant was neutralized with potassium hydroxide in an amount equimolar to its acid value and then dissolved in ion-exchange water to prepare an aqueous solution of resin dispersant with a resin (solids) content of 20.0%. A mixture was obtained by mixing 20.0 parts of pigment (CI Pigment Blue 15:3), 30.0 parts of the aqueous solution of resin dispersant, and 50.0 parts of ion-exchange water.

[0079] The resulting mixture and 200 parts of 0.3 mm diameter zirconia beads were placed in a batch-type vertical sand mill (manufactured by Imex) and dispersed for 5 hours while cooling with water. Afterwards, the mixture was centrifuged to remove coarse particles. The mixture was pressure-filtered through a 3.0 μm pore size microfilter (manufactured by Fujifilm), and then an appropriate amount of ion-exchanged water was added to obtain Pigment Dispersion 1. The resulting Pigment Dispersion 1 had a pigment content of 20.0% and a resin dispersant content of 6.0%. Pigment Dispersion 1 was used to prepare the first ink, which has a cyan hue.

[0080] Pigment Dispersion 2 will be described. A solution of 5.0 g of concentrated hydrochloric acid dissolved in 5.5 g of water was cooled to 5°C, and 1.6 g of 4-aminophthalic acid was added to this solution. The container containing this solution was placed in an ice bath and stirred to maintain the solution temperature below 10°C. A solution of 1.8 g of sodium nitrite dissolved in 9.0 g of ion-exchanged water at 5°C was added. After stirring for 15 minutes, 6.0 g of pigment was added under stirring and stirred for another 15 minutes to obtain a slurry. The pigment added under stirring was carbon black with a specific surface area of ​​220 m2 / g and a DBP oil absorption of 105 mL / 100 g. The resulting slurry was filtered through filter paper, the particles thoroughly washed with water, and dried in an oven at 110°C. The filter paper used was Advantec's "Standard Filter Paper No. 2." After replacing the counter ions from sodium ions with potassium ions using an ion exchange method, an appropriate amount of ion-exchanged water was added to adjust the pigment content, yielding Pigment Dispersion Liquid 2 with a pigment content of 20.0%. Pigment Dispersion Liquid 2 was used to prepare a second ink with a black hue.

[0081] Pigment Dispersion Liquid 3 will now be described. Pigment Dispersion Liquid 3, with a pigment content of 20.0% and a resin dispersant content of 4.0%, was obtained using the same procedure as for Pigment Dispersion Liquid 2 described above, except that the ingredients were changed to 20.0 parts of pigment (CI Pigment Magenta 122), 20.0 parts of an aqueous solution of resin dispersant, and 60.0 parts of ion-exchanged water. Pigment Dispersion Liquid 3 was used to prepare a third ink with a magenta hue.

[0082] Pigment Dispersion Liquid 4 will now be described. Pigment Dispersion Liquid 4 with a pigment content of 20.0% and a resin dispersant content of 6.0% was obtained using the same procedure as for Pigment Dispersion Liquid 2 described above, except that the pigment was changed to CI Pigment Yellow 74. Pigment Dispersion Liquid 4 was used to prepare a fourth ink with a yellow hue.

[0083] The ink preparation will now be described. The components (unit: %) shown in Table 1 were mixed, thoroughly stirred, and then pressure-filtered through a 0.8 μm pore size cellulose acetate filter (manufactured by Advantec) to prepare each ink. In Table 1, "Acetylenol E100" and "Acetylenol E60" are the trade names of surfactants manufactured by Kawaken Fine Chemicals. The bottom row of Table 1 shows the dynamic surface tension γ at a lifetime of 10 milliseconds. The dynamic surface tension γ was measured using a dynamic surface tensiometer using the maximum bubble pressure method at 25°C. The dynamic surface tensiometer used was a "Bubble Pressure Tensiometer BP-2" manufactured by Kruss.

[0084] Next, the arrangement of the nozzle arrays NL of the liquid jet head 10B according to Modification 1 will be described with reference to FIG. 13. FIG. 13 is a bottom view showing the ejection surface F2 of the liquid jet head 10B according to Modification 1. The liquid jet head 10B has a plurality of nozzle arrays NL. The nozzle arrays NL include nozzle arrays NLA1, NLA2, and NLA3 that eject a first ink, nozzle arrays NLB1, NLB2, and NLB3 that eject a second ink, nozzle arrays NLC1, NLC2, and NLC3 that eject a third ink, and nozzle arrays NLD1, NLD2, and NLD3 that eject a fourth ink. Note that when there is no need to distinguish between the nozzle arrays NLA1, NLA2, NLA3, NLB1, NLB2, NLB3, NLC1, NLC2, NLC3, NLD1, NLD2, and NLD3, they may be referred to as the nozzle array NL.

[0085] The liquid jet head 10B has a plurality of head chips 12. The head chip 12 is provided with a nozzle plate in which nozzles N are formed. The head chip 12 is provided with a nozzle row NL that ejects one type of ink. The head chip 12 has a pressure chamber and an actuator (not shown). The actuator increases the pressure of the ink in the pressure chamber, causing the ink to be ejected from the nozzle N.

[0086] The nozzle rows NLA1, NLA2, and NLA3 are arranged at different positions in the X-axis direction. The nozzle rows NLA1, NLA3 and the nozzle row NLA2 are arranged at different positions in the Y-axis direction. The nozzle row NLA2 is positioned higher in the Y2 direction than the nozzle rows NLA1 and NLA3. In the first attitude P1 of the liquid jet head 10B, the nozzle row NLA2 is positioned higher in the gravity direction G1 than the nozzle rows NLA1 and NLA3. In the first attitude P1, the ejection surface F2 is inclined with respect to the horizontal plane.

[0087] The nozzle rows NLB1, NLB2, and NLB3 are arranged in the same manner as the nozzle rows NLA1, NLA2, and NLA3. The nozzle rows NLB1, NLB2, and NLB3 and the nozzle rows NLA1, NLA2, and NLA3 are spaced apart from each other in the Y-axis direction.

[0088] The nozzle arrays NLC1, NLC2, and NLC3 are arranged in the same manner as the nozzle arrays NLA1, NLA2, and NLA3. The nozzle arrays NLC1, NLC2, and NLC3 are located between the nozzle arrays NLA1, NLA2, and NLA3 and the nozzle arrays NLB1, NLB2, and NLB3 in the Y-axis direction.

[0089] The nozzle arrays NLD1, NLD2, and NLD3 are arranged in the same manner as the nozzle arrays NLA1, NLA2, and NLA3. The nozzle arrays NLD1, NLD2, and NLD3 are located between the nozzle arrays NLC1, NLC2, and NLC3 and the nozzle arrays NLB1, NLB2, and NLB3 in the Y-axis direction.

[0090] The liquid jet device 1 may include a liquid jet head 10B instead of the liquid jet head 10. The liquid jet device 1 including the liquid jet head 10B achieves the same effects as the liquid jet device 1 including the liquid jet head 10 described above.

[0091] Next, the arrangement of the nozzle rows NL of the liquid jet head 10C according to Modification 2 will be described with reference to FIG. 14. FIG. 14 is a bottom view showing the ejection surface F3 of the liquid jet head 10C according to Modification 2. The liquid jet head 10C has a plurality of nozzle rows NL. The nozzle rows NL include a nozzle row NLA that ejects a first ink, a nozzle row NLB that ejects a second ink, a nozzle row NLC that ejects a third ink, and a nozzle row NLD that ejects a fourth ink. Note that when there is no need to distinguish between the nozzle rows NLA, NLB, NLC, and NLD, they may be referred to as the nozzle row NL.

[0092] The liquid jet head 10C has a plurality of head chips 12C. The head chip 12C is provided with a nozzle plate 11C in which nozzles N are formed. The head chip 12C is provided with nozzle rows NLA, NLB, NLC, and NLD.

[0093] Figure 14 shows the V-axis direction and the W-axis direction, which are perpendicular to each other. The V-axis direction and the W-axis direction are perpendicular to the Z-axis direction. The V-axis direction and the W-axis direction are directions based on the ejection surface F3. The V-axis direction includes the V1 direction and the V2 direction. The W-axis direction includes the W1 direction and the W2 direction. The V-axis direction intersects with the X-axis direction at an inclination angle α.

[0094] Multiple nozzle arrays NL extend along the V-axis direction. The nozzles N included in each nozzle array NL are aligned in the V-axis direction. The nozzle arrays NLA and NLD are aligned in the V-axis direction. The nozzle arrays NLA and NLD are spaced apart in the V-axis direction. The nozzle arrays NLA and NLD are spaced apart in the Y-axis direction. In FIG. 14, imaginary lines L3 and L4 are shown by two-dot chain lines. The imaginary lines L3 and L4 are spaced apart from each other in the Y-axis direction and are straight lines extending along the X-axis direction. The imaginary line L3 is located in the Y2 direction from the imaginary line L4. The nozzle arrays NLA and NLC are located in the Y2 direction from the imaginary line L3, and the nozzle arrays NLB and NLD are located in the Y1 direction from the imaginary line L4.

[0095] The nozzle rows NLC and NLB are aligned in the V-axis direction. The nozzle rows NLC and NLB are spaced apart in the V-axis direction. The nozzle rows NLC and NLB are spaced apart in the Y-axis direction. In the liquid jet head 10C, the nozzle rows NLA and NLC are an example of a first nozzle row, and the nozzle rows NLD and NLB are an example of a second nozzle row.

[0096] When viewed in the Y-axis direction, the nozzle row NLA at least partially overlaps with the nozzle rows NLD and NLB. For example, of two head chips 12C adjacent in the X-axis direction, the one arranged in the X1 direction is head chip 12C1, and the one arranged in the X2 direction from head chip 12C1 is head chip 12C2. When viewed in the Y-axis direction, the nozzle row NLA of head chip 12C1 and the nozzle rows NLD and NLB of head chip 12C2 at least partially overlap. Note that the nozzle row NLA and the nozzle rows NLD and NLB within the same head chip 12 may at least partially overlap in the Y-axis direction.

[0097] Similarly, when viewed in the Y-axis direction, nozzle row NLC at least partially overlaps with nozzle rows NLD and NLB. Nozzle row NLC of head chip 12C1 and nozzle rows NLD and NLB of head chip 12C2 at least partially overlap with each other when viewed in the Y-axis direction. Note that nozzle row NLC and nozzle rows NLD and NLB within the same head chip 12 may at least partially overlap with each other in the Y-axis direction.

[0098] When viewed in the X-axis direction, the nozzle row NLA and the nozzle rows NLD and NLB are arranged at intervals in the Y-axis direction. When viewed in the X-axis direction, the nozzle row NLC and the nozzle rows NLD and NLB are arranged at intervals in the Y-axis direction.

[0099] In the Y-axis direction, the distance between nozzle rows NLA and NLC provided on the same head chip 12C is narrower than the distance between nozzle rows NLC provided on head chip 12C1 and nozzle rows NLA provided on head chip 12C2.

[0100] Nozzle NA1 located at the bottom end of nozzle row NLA in the direction of gravity G1 is located higher than nozzle ND1 located at the bottom end of nozzle row NLD and nozzle NB1 located at the bottom end of nozzle row NLB in the direction of gravity G1.

[0101] Nozzle NC1 located at the bottom end of nozzle row NLC in the direction of gravity G1 is located higher than nozzle ND1 located at the bottom end of nozzle row NLD and nozzle NB1 located at the bottom end of nozzle row NLB in the direction of gravity G1.

[0102] The liquid ejecting apparatus 1 including such a liquid ejecting head 10C has the same effects as the liquid ejecting apparatus 1 including the liquid ejecting head 10 described above.

[0103] In a liquid ejection head 10C including nozzle rows NL that at least partially overlap with each other in the direction of gravity G1, when the problem of satellite droplets adhering to the upper nozzles N as described above is considered, it is desirable to determine the height relationship between the nozzle rows NL that at least partially overlap with each other by comparing the nozzles N that are located at the same position on the X-axis, which is the extension direction of the intersection line between the ejection surface F3 and the horizontal plane F0 when the nozzle rows NL are in the inclined position. This is because, when the intersection line between the ejection surface F3 and the horizontal plane F0 when the nozzle rows NL are in the inclined position is along the X-axis, satellite droplets that are separated from ink ejected from a nozzle N are likely to rise at the same position as the nozzle N on the X-axis and adhere to a nozzle N further above. Here, the X-axis along the extension direction of the intersection line between the ejection surface F3 and the horizontal plane F0 when the nozzle rows NL are in the inclined position is an example of a "virtual axis along the extension direction of the intersection line between the ejection surface and the horizontal plane when the nozzle rows NL are in the first position."

[0104] Furthermore, the problem of satellite droplets adhering to nozzle rows is likely to occur within the same head chip 12C. In this modified example, within the same head chip 12C, the nozzle rows NLA and NLC at least partially overlap with each other in the direction of gravity G1, and the nozzle rows NLB and NLD at least partially overlap with each other in the direction of gravity G1.

[0105] Here, when comparing nozzles NA of nozzle array NLA and nozzles NC of nozzle array NLC, which are located in the same head chip 12C and at the same position on the X-axis, it is preferable to interpret nozzle array NLA as a nozzle array above nozzle array NLC, since nozzle NA is located above nozzle NC. Similarly, when comparing nozzles ND of nozzle array NLD and nozzles NB of nozzle array NLB, which are located in the same head chip 12C and at the same position on the X-axis, it is preferable to interpret nozzle array NLD as a nozzle array above nozzle array NLB, since nozzle ND of nozzle array NLD is located above nozzle NB of nozzle array NLB. In this way, nozzle array NLA may be an example of a first nozzle array, nozzle array NLB an example of a second nozzle array, nozzle array NLC an example of a third nozzle array, and nozzle array NLD an example of a fourth nozzle array.

[0106] Next, the arrangement of the nozzle rows NL of the liquid jet head 10D according to Modification 3 will be described with reference to FIG. 15. FIG. 15 is a bottom view showing the ejection surface F4 of the liquid jet head 10D according to Modification 3. The liquid jet head 10D has a plurality of nozzle rows NL. The nozzle rows NL include a nozzle row NLA that ejects a first ink and a nozzle row NLB that ejects a second ink. Note that when there is no need to distinguish between the nozzle rows NLA and NLB, they may be referred to as the nozzle row NL.

[0107] The liquid jet head 10D has a plurality of head chips 12D. The head chip 12D is provided with a nozzle plate 11D in which nozzles N are formed. The head chip 12D is provided with nozzle rows NLA and NLB.

[0108] Multiple nozzle arrays NL extend along the V-axis direction. The nozzles N included in each nozzle array NL are aligned in the V-axis direction. The nozzle arrays NLA and NLB are arranged at different positions in the W-axis direction. When viewed in the W-axis direction, the nozzle arrays NLA and NLB at least partially overlap. When viewed in the Y-axis direction, the nozzle arrays NLA and NLB at least partially overlap. When viewed in the X-axis direction, the nozzle arrays NLA and NLB at least partially overlap.

[0109] When viewed in the X-axis direction, the nozzle row NLA and the nozzle row NLB at least partially overlap, that is, the nozzle row NLA and the nozzle row NLB at least partially overlap with respect to the direction of gravity G1. The nozzle NA1 located at the bottom end of the nozzle row NLA with respect to the direction of gravity G1 is located higher than the nozzle NB1 located at the bottom end of the nozzle row NLB with respect to the direction of gravity G1.

[0110] Furthermore, when comparing nozzles NA of nozzle array NLA and nozzle NB of nozzle array NLB, which are located at the same position on the X-axis within the same head chip 12D, the nozzle NA of nozzle array NLA is located higher than the nozzle NB of nozzle array NLB. Therefore, when considering the issue of satellite droplets that separate from ink droplets adhering to the upper nozzle N, in the liquid ejection head 10D, similar to the above-described second modification, the nozzle array NLA can be considered an example of a first nozzle array, and the nozzle array NLB can be considered an example of a second nozzle array.

[0111] The liquid ejecting apparatus 1 including such a liquid ejecting head 10D has the same effects as the liquid ejecting apparatus 1 including the liquid ejecting head 10 described above.

[0112] Next, the arrangement of the nozzle rows NL of the liquid jet heads 10G, 10H according to Modification 4 will be described with reference to FIG. 16. FIG. 16 is a bottom view showing the ejection surfaces of the liquid jet heads 10G, 10H according to Modification 4. The liquid jet device 1 shown in FIG. 1 may include a head unit 20 having a plurality of liquid jet heads 10G, 10H, instead of the liquid jet head 10. The head unit 20 has a plurality of liquid jet heads 10G, 10H arranged alternately in the X-axis direction. FIG. 16 illustrates a plurality of liquid jet heads 10G and a liquid jet head 10H arranged between the plurality of liquid jet heads 10G.

[0113] The liquid ejection head 10G includes a plurality of nozzle arrays NL, including a nozzle array NLA1 that ejects a first ink, a nozzle array NLB1 that ejects a second ink, a nozzle array NLC1 that ejects a third ink, and a nozzle array NLD1 that ejects a fourth ink.

[0114] The liquid jet head 10G has a plurality of head chips 12G1, 12G2, 12G3, and 12G4. The head chip 12G1 is provided with a nozzle array NLA1, the head chip 12G2 is provided with a nozzle array NLB1, the head chip 12G3 is provided with a nozzle array NLC1, and the head chip 12G4 is provided with a nozzle array NLD1.

[0115] In the liquid jet head 10G, the nozzle array NLA1 is an example of a first nozzle array, the nozzle array NLB1 is an example of a second nozzle array, the nozzle array NLC1 is an example of a third nozzle array, and the nozzle array NLD1 is an example of a fourth nozzle array. The multiple nozzle arrays NLA1, NLB1, NLC1, and NLD1 extend in the X-axis direction. In the Y1 direction, the nozzle arrays are arranged in the following order: nozzle array NLA1, nozzle array NLC1, nozzle array NLD1, and nozzle array NLB1. When arranged in order from longest to shortest in the X-axis direction, the order is: nozzle array NLB1, nozzle array NLD1, nozzle array NLC1, and nozzle array NLA1. The nozzle array NLB1 is longer than the nozzle array NLA1 in the X-axis direction. When arranged in order from highest to lowest in an inclined posture of the head unit 20, the order is: nozzle array NLA1, nozzle array NLC1, nozzle array NLD1, and nozzle array NLB1.

[0116] The liquid ejection head 10H includes a plurality of nozzle arrays NL, including a nozzle array NLA2 that ejects a first ink, a nozzle array NLB2 that ejects a second ink, a nozzle array NLC2 that ejects a third ink, and a nozzle array NLD2 that ejects a fourth ink.

[0117] The liquid jet head 10H has a plurality of head chips 12H1, 12H2, 12H3, and 12H4. The head chip 12H1 is provided with a nozzle array NLA2, the head chip 12H2 is provided with a nozzle array NLB2, the head chip 12H3 is provided with a nozzle array NLC2, and the head chip 12H4 is provided with a nozzle array NLD2.

[0118] In the liquid jet head 10H, the nozzle array NLA2 is an example of a first nozzle array, the nozzle array NLB2 is an example of a second nozzle array, the nozzle array NLC2 is an example of a third nozzle array, and the nozzle array NLD2 is an example of a fourth nozzle array. The multiple nozzle arrays NLA2, NLB2, NLC2, and NLD2 extend in the X-axis direction. In the Y1 direction, the nozzle arrays are arranged in the following order: nozzle array NLA2, nozzle array NLC2, nozzle array NLD2, and nozzle array NLB2. When arranged in order from longest to shortest in the X-axis direction, the order is: nozzle array NLA2, nozzle array NLC2, nozzle array NLD2, and nozzle array NLB2. The nozzle array NLA2 is longer than the nozzle array NLB2 in the X-axis direction. When arranged in order from highest to lowest in an inclined posture of the head unit 20, the order is: nozzle array NLA2, nozzle array NLC2, nozzle array NLD2, and nozzle array NLB2.

[0119] The liquid ejecting apparatus 1 including such liquid ejecting heads 10G, 10H has the same effects as the liquid ejecting apparatus 1 including the liquid ejecting head 10 described above.

[0120] Next, a liquid ejecting apparatus 1B according to a second embodiment will be described with reference to FIG. 17. FIG. 17 is a schematic diagram showing the liquid ejecting apparatus 1B according to the second embodiment. The liquid ejecting apparatus 1B includes a plurality of liquid ejecting heads 30A to 30E, a drum 35 that transports a medium PA, and pressure adjusting units 38A to 38E. Note that, in the description of the second embodiment, descriptions that are the same as those of the first embodiment will be omitted. The X-axis direction, Y-axis direction, and Z-axis direction shown in each figure differ depending on the posture of the liquid ejecting heads 30A to 30E. Note that the drum 35 may be an intermediate transfer body on which ink ejected from the liquid ejecting heads 30A to 30E lands.

[0121] The drum 35 rotates around a rotation axis 35a extending in the X-axis direction. The medium PA is transported in accordance with the rotation of the drum 35. The medium PA passes through positions corresponding to the liquid jet heads 30A to 30E. Ink is ejected from the liquid jet heads 30A to 30E onto the moving medium PA.

[0122] The liquid jet heads 30A to 30E are arranged at different positions in the circumferential direction of the drum 35. The ejection surfaces F31 to F35 of the liquid jet heads 30A to 30E are arranged at different angles. The ejection surfaces F31 to F35 are surfaces of nozzle plates. The liquid jet heads 30A to 30E have a common structure.

[0123] 18 is a schematic diagram showing the attitude of the liquid jet head 30A. The liquid jet head 30A has a nozzle array NLA that ejects a first ink. The nozzle array NLA is formed on an ejection surface F31 of the liquid jet head 30A. The multiple nozzles NA included in the nozzle array NLA are aligned in the X-axis direction. The LA direction, which is perpendicular to the ejection surface F31, is aligned with the direction of gravity G1. Ink ejected from the nozzles NA of the liquid jet head 30A flies downward in the direction of gravity G1.

[0124] FIG. 19 is a schematic diagram showing the attitude of the liquid jet head 30B. The liquid jet head 30B has a nozzle row NLB that ejects the second ink. The nozzle row NLB is formed on the ejection surface F32 of the liquid jet head 30B. The multiple nozzles NB included in the nozzle row NLB are aligned in the X-axis direction. The LB direction perpendicular to the ejection surface F32 is aligned with the direction of gravity G1. FIG. 19 also shows an upward direction G2 that is the opposite direction to the direction of gravity G1. Ink ejected from the nozzle NB of the liquid jet head 30B flies in the upward direction G2.

[0125] The liquid jet head 30A is an example of a first liquid jet head, and the liquid jet head 30B is an example of a second liquid jet head. The ejection surface F31 is an example of a first ejection surface, and the ejection surface F32 is an example of a second ejection surface. The nozzle NA is an example of a first nozzle that ejects the first ink, and the nozzle NB is an example of a second nozzle that ejects the second ink. The dynamic surface tension of the first ink is lower than the dynamic surface tension of the second ink.

[0126] In the liquid jet head 30A shown in FIG. 18, the angle β1 formed between the ejection direction of the first ink ejected from the nozzle row NLA and the direction of gravity G1 is 0 degrees. The angle β1 is an example of a first angle. In the liquid jet head 30B shown in FIG. 19, the angle β2 formed between the ejection direction of the second ink ejected from the nozzle row NLB and the direction of gravity G1 is 180 degrees. The angle β2 is an example of a second angle. The angle β2 is greater than the angle β1.

[0127] FIG. 20 is a schematic diagram showing the attitude of the liquid jet head 30C. The liquid jet head 30C has a nozzle row NLC that ejects a third ink. The nozzle row NLC is formed on the ejection surface F33 of the liquid jet head 30C. The multiple nozzles NC included in the nozzle row NLC are aligned in the X-axis direction. The LC direction perpendicular to the ejection surface F33 is aligned along the K1 direction, which is perpendicular to the direction of gravity G1. FIG. 20 shows the K1 direction, which is perpendicular to the direction of gravity G1. Ink ejected from the nozzles NC of the liquid jet head 30C flies along the K1 direction, which is perpendicular to the direction of gravity G1.

[0128] The liquid jet head 30C is an example of a third liquid jet head. The jetting surface F33 is an example of a third jetting surface. The nozzle NC is an example of a third nozzle that jets a third ink. The dynamic surface tension of the third ink is greater than the dynamic surface tension of the first ink and less than the dynamic surface tension of the second ink.

[0129] The angle β3 formed between the direction K1, which is the ejection direction of the third ink ejected from the nozzle NC, and the direction of gravity G1 is 90 degrees. The angle β3 is an example of a third angle. The angle β3 is larger than the angle β1 and smaller than the angle β2.

[0130] FIG. 21 is a schematic diagram showing the attitude of the liquid jet head 30D. The liquid jet head 30D has a nozzle array NLD that ejects a fourth ink. The nozzle array NLD is formed on the ejection surface F34 of the liquid jet head 30D. The multiple nozzles ND included in the nozzle array NLD are aligned in the X-axis direction. The LD direction, which is perpendicular to the ejection surface F34, is aligned with the direction Z1 that intersects with the direction of gravity G1 and the K-axis direction. FIG. 21 also shows the direction K1 that is perpendicular to the direction of gravity G1. Ink ejected from the nozzles ND of the liquid jet head 30D flies obliquely upward along the direction Z1 that intersects with the direction of gravity G1.

[0131] The liquid jet head 30D is an example of a fourth liquid jet head. The jetting surface F34 is an example of a fourth jetting surface. The nozzle ND is an example of a fourth nozzle that jets a fourth ink. The dynamic surface tension of the fourth ink is greater than the dynamic surface tension of the third ink and less than the dynamic surface tension of the second ink.

[0132] The angle β4 formed by the ejection direction of the fourth ink ejected from the nozzle ND, i.e., the Z1 direction in FIG. 21 and the gravity direction G1, is 135 degrees. The angle β4 is an example of a fourth angle. The angle β4 is larger than the angle β3 and smaller than the angle β2.

[0133] FIG. 22 is a schematic diagram showing the attitude of the liquid jet head 30E. The liquid jet head 30E has a nozzle array NLE that ejects a fifth ink. The nozzle array NLE is formed on the ejection surface F35 of the liquid jet head 30E. The multiple nozzles NE included in the nozzle array NLE are aligned in the X-axis direction. The LE direction, which is perpendicular to the ejection surface F35, is along a direction that intersects with the direction of gravity G1 and the K-axis direction. FIG. 22 also shows a direction K1 that is perpendicular to the direction of gravity G1. Ink ejected from the nozzle NE of the liquid jet head 30E flies diagonally downward in a direction that intersects with the direction of gravity G1 and the K-axis direction, that is, along the Z1 direction in FIG. 22.

[0134] The liquid jet head 30E is an example of a fifth liquid jet head. The jet surface F35 is an example of a fifth jet surface. The nozzle NE is an example of a fifth nozzle that jets a fifth ink. The dynamic surface tension of the fifth ink is greater than the dynamic surface tension of the first ink and less than the dynamic surface tension of the third ink.

[0135] The angle β5 formed by the ejection direction of the fifth ink ejected from the nozzle NE, i.e., the Z1 direction in FIG. 22 and the gravity direction G1, is 45 degrees. The angle β5 is an example of a fifth angle. The angle β5 is larger than the angle β1 and smaller than the angle β3.

[0136] Next, the head differences H1 to H5 in the nozzle rows NLA to NLE will be described with reference to FIG. 17. The liquid jet head 30A is provided with a pressure adjustment unit 38A. The liquid jet head 30B is provided with a pressure adjustment unit 38B. The liquid jet head 30C is provided with a pressure adjustment unit 38C. The liquid jet head 30D is provided with a pressure adjustment unit 38D. The liquid jet head 30E is provided with a pressure adjustment unit 38E. The pressure adjustment unit 38A is connected to the nozzle row NLA. The pressure adjustment unit 38B is connected to the nozzle row NLB. The pressure adjustment unit 38C is connected to the nozzle row NLC. The pressure adjustment unit 38D is connected to the nozzle row NLD. The pressure adjustment unit 38E is connected to the nozzle row NLE.

[0137] The pressure adjustment units 38A to 38E adjust the pressure of ink supplied to the liquid ejection heads 30A to 30E so that a predetermined pressure acts on the nozzles NA to NE. The pressure adjustment units 38A to 38E are, for example, negative pressure generating units including pressure adjustment valves. These negative pressure generating units may have, for example, a pressure adjustment valve that opens and closes the ink flow path, and a flexible member that bends based on the differential pressure between the pressure in the ink flow path downstream of the pressure adjustment valve and atmospheric pressure, and may be configured to control the opening and closing of the pressure adjustment valve by moving the pressure adjustment valve through the bending of this flexible member so that a predetermined range of negative pressure acts on the nozzles N. The pressure adjustment units 38A to 38E have a common structure.

[0138] The pressure adjusting units 38A-38E may also adjust the pressure of ink supplied to the liquid jet heads 30A-30E using a sub-tank that temporarily stores ink. Specifically, the pressure adjusting units 38A-38E may have a sub-tank and any sensor capable of detecting the amount of ink stored in the sub-tank, and when the amount of ink stored in the sub-tank detected by the sensor falls below a threshold, the pressure adjusting units 38A-38E may replenish the ink from the liquid container 2 to maintain the amount of ink stored in the sub-tank at a substantially constant level, i.e., maintain the liquid level of the ink stored in the sub-tank at a substantially constant level, thereby adjusting the pressure of the ink in the liquid jet heads 30A-30E based on the head difference between the liquid level in the sub-tank and the liquid jet heads 30A-30E. The pressure in the sub-tank may also be adjusted to a predetermined pressure using a compressor, thereby adjusting the pressure of the ink supplied to the liquid jet heads 30A-30E.

[0139] The pressure adjustment section 38A adjusts the pressure of the first ink. The pressure adjustment section 38B adjusts the pressure of the second ink. The pressure adjustment section 38C adjusts the pressure of the third ink. The pressure adjustment section 38D adjusts the pressure of the fourth ink. The pressure adjustment section 38E adjusts the pressure of the fifth ink. The head units 40A to 40E include pressure adjustment sections 38A to 38E and liquid ejection heads 30A to 30E.

[0140] As described above, the liquid jet heads 30A to 30E have a common structure, and the pressure adjustment units 38A to 38E also have a common structure. Therefore, the head unit 40A, head unit 40B, head unit 40C, head unit 40D, and head unit 40E have a common structure. Therefore, the resistance of the ink flow path in each of the liquid jet heads 30A to 30E is the same. Specifically, the flow path resistance from the pressure adjustment unit 38A to the nozzle NA of the nozzle row NLA is the same as the flow path resistance from the pressure adjustment unit 38B to the nozzle NB of the nozzle row NLB.

[0141] Similarly, the flow path resistance from the pressure adjustment unit 38A to the nozzle NA of the nozzle row NLA is the same as the flow path resistance from the pressure adjustment unit 38C to the nozzle NC of the nozzle row NLC. The flow path resistance from the pressure adjustment unit 38A to the nozzle NA of the nozzle row NLA is the same as the flow path resistance from the pressure adjustment unit 38D to the nozzle ND of the nozzle row NLD. The flow path resistance from the pressure adjustment unit 38A to the nozzle NA of the nozzle row NLA is the same as the flow path resistance from the pressure adjustment unit 38E to the nozzle NE of the nozzle row NLE.

[0142] The liquid ejecting device 1B also includes a support portion that supports the head units 40A to 40E. The support portion is not shown. The support portion may have any structure as long as it can support the head units 40A to 40E. The support portion may support the head units 40A to 40E separately, or may support the head units 40A to 40E collectively.

[0143] The liquid jet head 30A having the ejection surface F31 and the pressure adjustment unit 38A can be attached to and detached from the support unit as a single unit. Similarly, the liquid jet heads 30B to 30E having the ejection surfaces F32 to F35 and the pressure adjustment units 38B to 38E can be attached to and detached from the support unit as a single unit.

[0144] Furthermore, since the head units 40A to 40E have the same structure, the relative positional relationship between the ejection surface F31 and the pressure adjustment unit 38A, the relative positional relationship between the ejection surface F32 and the pressure adjustment unit 38B, the relative positional relationship between the ejection surface F33 and the pressure adjustment unit 38C, the relative positional relationship between the ejection surface F34 and the pressure adjustment unit 38D, and the relative positional relationship between the ejection surface F35 and the pressure adjustment unit 38E are all the same.

[0145] FIG. 17 shows the height positions HA, HB, HC, HD, and HE of the nozzle rows NLA, NLB, NLC, NLD, and NLE. When arranged in order from highest to lowest, the height positions are HA, HE, HC, HD, and HB. Pressure adjustment unit 38A is located above height position HA. Pressure adjustment unit 38B is located below height position HB. Pressure adjustment unit 38C is at the same height as height position HC. Pressure adjustment unit 38D is located below height position HD. Pressure adjustment unit 38E is located above height position HE.

[0146] The head difference H1 between the pressure adjustment unit 38A and the nozzle row NLA is greater than the head difference H5 between the pressure adjustment unit 38E and the nozzle row NLE. The head difference H5 is greater than the head difference H3 between the pressure adjustment unit 38C and the nozzle row NLC. Note that the head difference H3 is not shown. The head difference H3 is greater than the head difference H4 between the pressure adjustment unit 38D and the nozzle row NLD. The head difference H4 is greater than the head difference H2 between the pressure adjustment unit 38B and the nozzle row NLB.

[0147] The head differences H1 to H5 in this specification are based on the nozzle row NL of each liquid jet head 30A to 30E. When the pressure adjustment units 38A to 38E are positioned higher in the upward direction G2 than the nozzle row NL, the head differences H1 to H5 have positive values. When the pressure adjustment units 38A to 38E are positioned higher in the gravity direction G1 than the nozzle row NL, the head differences H1 to H5 have negative values. Based on this premise, the head differences are arranged in order from largest to smallest as follows: H1, H5, H3, H4, H2.

[0148] The liquid ejecting device 1B according to the second embodiment also achieves the same effects as the liquid ejecting device 1 according to the first embodiment.

[0149] In the liquid ejection device 1B, the positions of the nozzle arrays NLA, NLB, NLC, NLD, and NLE differ depending on the dynamic surface tension of the ink. The nozzle array NLA, which ejects the first ink, which has the smallest dynamic surface tension, is positioned higher in the direction of gravity G1 than the other nozzle arrays NLB, NLC, NLD, and NLE. The first ink, which has the smallest dynamic surface tension, is supplied to the nozzle array NLA, which has the largest head difference H1.

[0150] In the liquid ejecting device 1B, the nozzle row NLB that ejects the second ink having the highest dynamic surface tension is positioned lower in the direction of gravity G1 than the other nozzle rows NLA, NLC, NLD, and NLE. The second ink having the highest dynamic surface tension is supplied to the nozzle row NLB that has the smallest head difference H2.

[0151] In the liquid ejection device 1B, the nozzles NA of the nozzle array NLA that ejects the first ink, which has a smaller dynamic surface tension, are positioned higher in the direction of gravity G1 than the nozzles NB of the nozzle array NLB that ejects the second ink, which has a larger dynamic surface tension, so that the variation in the ink supply characteristics to the multiple nozzle arrays NL that eject different types of ink can be reduced, thereby suppressing the variation in the ink ejection characteristics of the multiple nozzle arrays NL, thereby improving the printing accuracy of the liquid ejection device 1B.

[0152] In the liquid ejection device 1B, the nozzles NC of the nozzle array NLC that eject the third ink are positioned between the nozzles NA of the nozzle array NLA and the nozzles NB of the nozzle array NLB in the direction of gravity G1. The third ink, which has a dynamic surface tension greater than that of the first ink, is supplied to the nozzles NC of the nozzle array NLC for which the head difference H3 is smaller than the head difference H1. The third ink, which has a dynamic surface tension less than that of the second ink, is supplied to the nozzles of the nozzle array NLC for which the head difference H3 is larger than the head difference H2.

[0153] In the liquid ejection device 1B, the nozzles ND of the nozzle array NLD that eject the fourth ink are positioned between the nozzles NC of the nozzle array NLC and the nozzles NB of the nozzle array NLB in the direction of gravity G1. The fourth ink, which has a dynamic surface tension greater than that of the third ink, is supplied to the nozzles ND of the nozzle array NLD whose head difference H4 is smaller than the head difference H3. The fourth ink, which has a dynamic surface tension less than that of the second ink, is supplied to the nozzles ND of the nozzle array NLD whose head difference H4 is greater than the head difference H2.

[0154] In the liquid ejection device 1B, the nozzles NE of the nozzle array NLE that eject the fifth ink are positioned between the nozzles NA of the nozzle array NLA and the nozzles NC of the nozzle array NLC in the direction of gravity G1. The fifth ink, which has a dynamic surface tension greater than that of the first ink, is supplied to the nozzles of the nozzle array NLE whose head difference H5 is smaller than the head difference H1. The fifth ink, which has a dynamic surface tension less than that of the third ink, is supplied to the nozzles NE of the nozzle array NLE whose head difference H5 is greater than the head difference H3.

[0155] In this liquid ejection device 1B, the height positions of the nozzles NA to NE vary depending on the dynamic surface tension of the ink, which reduces the variation in ink supply characteristics to the multiple nozzles NA to NE that eject different types of ink, thereby suppressing the variation in ink ejection characteristics of the multiple nozzles NA to NE, thereby improving the printing accuracy of the liquid ejection device 1B.

[0156] It should be noted that the above-described embodiment merely shows a typical form of the present invention, and the present invention is not limited to the above-described embodiment, and various modifications and additions are possible within the scope that does not deviate from the gist of the present invention.

[0157] In the above embodiment, a plurality of inks of different colors are illustrated, but this is not limiting. For example, the first ink and the second ink may have different dynamic surface tensions and may be the same color.

[0158] In the above-described embodiment, a line-type liquid ejection device 1 equipped with a line head is exemplified, but the present invention may also be applied to a serial-type liquid ejection device in which a carriage carrying a liquid ejection head 10 is moved back and forth in the width direction of the medium PA.

[0159] The liquid ejection device 1 illustrated in the above-described embodiment can be employed in various devices such as facsimile machines and copiers, as well as devices dedicated to printing. However, the use of the liquid ejection device of the present invention is not limited to printing. For example, a liquid ejection device that ejects a solution of a color material is used as a manufacturing device for forming color filters for display devices such as liquid crystal display panels. Furthermore, a liquid ejection device that ejects a solution of a conductive material is used as a manufacturing device for forming wiring and electrodes on a wiring board. Furthermore, a liquid ejection device that ejects a solution of an organic substance related to a living organism is used as a manufacturing device for manufacturing biochips, for example. [Explanation of symbols]

[0160] 1, 1B...liquid ejection device, 1a...housing, 10, 10B to 10D, 10G, 10H...liquid ejection head, 11...nozzle plate, 30A...liquid ejection head, 30B...liquid ejection head, 30C to 30E...liquid ejection head, 38A...pressure adjustment unit, 38B...pressure adjustment unit, F0...horizontal plane, F1...ejection surface, F31...ejection surface, F32...ejection surface, G1...direction of gravity, L1...first imaginary line, N...nozzle, NL...nozzle row, NLA...nozzle row, NLB...nozzle row, NLC...nozzle row, NLD...nozzle row, Q1...first contact, Q2...second contact, S1...rotation axis, X...X-axis direction, Y...Y-axis direction, Z...Z-axis direction.

Claims

1. A nozzle array including a first nozzle array for ejecting a first ink and a second nozzle array for ejecting a second ink. a liquid ejection head having a projection surface, The liquid ejection head can be held in a first position in which the ejection surface is inclined with respect to a horizontal plane. 、 the dynamic surface tension of the second ink is greater than the dynamic surface tension of the first ink; In the first attitude, the first nozzle row is closer to the second nozzle row in the gravity direction. A liquid injection device located above.

2. The difference between the dynamic surface tension of the first ink and the dynamic surface tension of the second ink is 1.0 mN.

2. The liquid ejecting apparatus according to claim 1, wherein the thickness is 1 / m or more.

3. The dynamic surface tension of the second ink at a life time of 10 msec is The liquid ejecting apparatus according to claim 1 , wherein the dynamic surface tension of the first ink is greater than the dynamic surface tension of the second ink.

4. The first nozzle row and the second nozzle row are formed in a common nozzle plate. The liquid ejection device according to any one of claims 1 to 3.

5. a direction in which an intersection line between the ejection surface and a horizontal plane in the first attitude extends is defined as a first direction; When a direction perpendicular to the first direction in the ejection surface is defined as a second direction, When viewed in the second direction, the first nozzle row and the second nozzle row at least partially overlap each other. The liquid ejecting apparatus according to claim 4 .

6. a direction in which an intersection line between the ejection surface and a horizontal plane in the first attitude extends is defined as a first direction; When viewed in the first direction, the first nozzle row and the second nozzle row are arranged with a gap therebetween. The liquid ejecting apparatus according to any one of claims 1 to 5,

7. At the same position on a virtual axis along an extension direction of a line of intersection between the ejection surface and a horizontal plane in the first attitude. The nozzles of the first nozzle row located at the same position on the virtual axis are the nozzles of the second nozzle row located at the same position on the virtual axis. The nozzles of any one of claims 1 to 6 are positioned above the nozzles of the nozzle row in the direction of gravity. The liquid ejection apparatus described herein.

8. the ejection surface further includes a third nozzle row that ejects a third ink, The dynamic surface tension of the third ink is greater than the dynamic surface tension of the first ink, 2. The dynamic surface tension of the ink is smaller than that of the ink. In the first attitude, the third nozzle row is closer to the first nozzle row in the gravity direction.

8. The method according to claim 1, wherein the nozzles are arranged below the first nozzle row and above the second nozzle row. Liquid injection device.

9. the ejection surface further includes a fourth nozzle row that ejects a fourth ink, The dynamic surface tension of the fourth ink is smaller than the dynamic surface tension of the second ink, 3. The dynamic surface tension of the ink is greater than that of the ink. In the first attitude, the fourth nozzle row is closer to the third nozzle row in the gravitational direction. The liquid ejecting apparatus according to claim 8 , wherein the nozzle row is located below and above the second nozzle row.

10. The liquid ejection head has a first posture and a second posture different from the first posture. It can be changed into multiple positions, including The liquid ejection head is in a direction along which an intersection line between the ejection surface and a horizontal plane in the first attitude is extended. The movable member is rotatable about a rotation axis along a first direction, When viewed in the first direction, the centers of the first nozzle row and the second nozzle row in the first attitude are When a line passing through the ejection surface and extending in a direction perpendicular to the ejection surface in the first attitude is defined as a first virtual line, , the rotation axis is located on the first nozzle row side as viewed from the first virtual line, 2. The liquid ejection apparatus according to claim 1 .

11. The first attitude is a recording operation by ejecting the first ink and the second ink onto a medium. This is the recording posture for the second posture is a maintenance posture for performing maintenance of the liquid jet head; The liquid ejection apparatus according to claim 10.

12. 12. The method according to claim 10, wherein in the second attitude, the ejection surface is parallel to a horizontal plane. Liquid injection device.

13. a housing that houses the liquid jet head, The housing has a first orientation that is an extension direction of an intersection line between the ejection surface and a horizontal plane in the first orientation. a portion that contacts a floor surface when the housing is placed on the floor surface, as viewed in the first direction; a first tangent located at one end of a third direction perpendicular to both the first direction and the direction of gravity, points, In the first attitude, the distance between the first contact point and the second nozzle row is The liquid jet nozzle according to any one of claims 1 to 12, wherein the distance between the first nozzle row and the second nozzle row is greater than the distance between the first nozzle row and the second nozzle row. shooting device.

14. When viewed in the first direction, the housing has a portion that contacts the floor surface when placed on the floor surface. a second contact located at the other end in the third direction, When viewed in the first direction, the center of gravity of the liquid ejection device is located at a position parallel to the second contact point with respect to the third direction. The liquid ejection device of claim 13 , wherein the first contact point is closer to the first contact point than the second contact point.

15. In the first attitude, the first ink is discharged from the first nozzle row onto the ejection surface. and a cleaning operation for discharging the second ink from the second nozzle row onto the ejection surface. The liquid ejecting apparatus according to claim 1 , further comprising:

16. a first liquid ejection head having a first ejection surface including a first nozzle that ejects a first ink; a second liquid ejection head having a second ejection surface including a second nozzle for ejecting a second ink; Preparation, the dynamic surface tension of the second ink is greater than the dynamic surface tension of the first ink; The angle between the ejection direction of the first ink ejected from the first nozzle and the direction of gravity is The first ejection surface is disposed so as to be at an angle; The angle between the ejection direction of the second ink ejected from the second nozzle and the direction of gravity is The second ejection surface is disposed at a second angle greater than the first angle. Device.

17. a first pressure adjusting unit that adjusts a pressure of the first ink supplied to the first nozzle; a second pressure adjusting unit that adjusts the pressure of the second ink supplied to the second nozzles. 、 The relative position of the first pressure adjustment unit with respect to the first ejection surface is The liquid ejecting apparatus according to claim 16 , wherein the relative position of the first pressure adjusting portion is the same as that of the second pressure adjusting portion.

18. The difference between the dynamic surface tension of the first ink and the dynamic surface tension of the third ink is 1.0 mN / m or more, The difference between the dynamic surface tension of the second ink and the dynamic surface tension of the third ink is 1.0 mN. The liquid ejecting apparatus according to claim 8 , wherein the ratio of the thickness of the ink droplets to the thickness of the ink droplets is equal to or greater than 1 / m.

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