Liquid jet head and liquid jet recording device

Abstract

This liquid jet head comprises: a jet unit including a plurality of nozzles, a plurality of pressure chambers, and a common liquid flow path that extends along the arrangement direction of the plurality of pressure chambers and communicates with each of the plurality of pressure chambers; and a drive unit that drives the jet unit on the basis of a drive signal having one or more pulses within a predetermined printing cycle to jet from the nozzles the liquid with which the pressure chambers are filled. At a discharge timing in which the plurality of nozzles include both a discharging nozzle Hnj from which the liquid is discharged and a non-discharging nozzle Hnn from which the liquid is not discharged, the drive unit performs non-discharging drive for the non-discharging nozzle Hnn so that only a non-discharging pulse Pb, which has a pulse width Wb within a range that the liquid is not discharged from the non-discharging nozzle Hnn and which micro-vibrates a meniscus in a pressure chamber communicating with the non-discharging nozzle Hnn, is included in the drive signal.

Description

Liquid ejection head and liquid ejection recording apparatus

[0001] The present disclosure relates to a liquid ejection head and a liquid ejection recording apparatus.

[0002] Liquid ejection recording apparatuses equipped with liquid ejection heads are used in various fields, and various types of liquid ejection heads have been developed (see, for example, Patent Document 1).

[0003] Japanese Patent No. 4104277

[0004] In such liquid ejection heads, generally, it is required to improve the ejection stability of the liquid. It is desirable to provide a liquid ejection head and a liquid ejection recording apparatus capable of improving the ejection stability of the liquid.

[0005] A liquid ejection head according to an embodiment of the present disclosure includes an ejection unit having a plurality of nozzles that eject liquid, a plurality of pressure chambers that communicate individually with the plurality of nozzles and are filled with liquid respectively, and a common flow path of the liquid that extends along the arrangement direction of the plurality of pressure chambers and communicates with the plurality of pressure chambers respectively, and a drive unit that drives the ejection unit based on a drive signal having one or more pulses within a predetermined printing cycle, thereby ejecting the liquid filled in the pressure chamber from the nozzle. The drive unit performs non-ejection driving for non-ejection nozzles such that only non-ejection pulses, which have a pulse width within a range where no liquid is ejected from the non-ejection nozzles and that cause minute vibration of the meniscus in the pressure chamber communicating with the non-ejection nozzles, are included in the drive signal at the ejection timing when both ejection nozzles where liquid is ejected and non-ejection nozzles where no liquid is ejected are included among the plurality of nozzles.

[0006] A liquid ejection recording apparatus according to an embodiment of the present disclosure includes the liquid ejection head according to an embodiment of the present disclosure.

[0007] According to the liquid ejection head and the liquid ejection recording apparatus according to an embodiment of the present disclosure, it is possible to improve the ejection stability of the liquid.

[0008] This is a schematic perspective view showing a schematic configuration example of a liquid jet recording device according to one embodiment of the present disclosure. This is a schematic diagram showing a schematic configuration example of an inkjet head and ink circulation mechanism according to the embodiment. This is an exploded perspective view showing a configuration example of a head chip according to the embodiment. This is a cross-sectional view corresponding to the line IV-IV in Figure 3. This is a cross-sectional view corresponding to the line V-V in Figure 3. This is a cross-sectional view corresponding to the line VI-VI in Figure 4. This is a cross-sectional view corresponding to the line VII-VII in Figure 4. This is a schematic diagram showing an example of the supply path of each potential supplied from the drive unit to the drive electrode. This is a timing diagram schematically showing an example of the waveform of a drive signal. This is a timing diagram schematically showing various waveform examples in the drive signal. This is a schematic diagram showing an example of the ink ejection pattern from multiple nozzle holes. This is a schematic diagram showing another example of the ink ejection pattern from multiple nozzle holes. This is a schematic diagram for explaining the mixing of air bubbles into the inside of a non-ejecting nozzle. This is a schematic diagram for explaining minute vibrations of the meniscus inside a non-ejecting nozzle. This is a diagram showing an example of ejection drive and non-ejecting drive according to the embodiment. This is a timing diagram schematically showing an example of the drive signal during ejection drive and non-ejecting drive shown in Figure 15. This timing diagram schematically shows examples of pressure waves corresponding to discharge nozzles and non-discharge nozzles.

[0009] The embodiments of this disclosure will be described in detail below with reference to the drawings. The description will be in the following order: 1. Embodiment (Example when applied to a circulating liquid injection head) 2. Modified examples

[0010] <1. Embodiments> [A. Overall Configuration of Printer 1] Figure 1 is a schematic perspective view showing an example of the general configuration of printer 1 as a liquid jet recording device according to one embodiment of the present disclosure. Printer 1 is an inkjet printer that uses ink 9, which will be described later, to record (print) images, characters, etc., on recording paper P, which is the recording medium. Note that the recording medium is not limited to paper, but includes other recordable materials such as ceramics and glass.

[0011] As shown in Figure 1, the printer 1 comprises a pair of transport mechanisms 2a and 2b, an ink tank 3, an inkjet head 4, an ink circulation mechanism 8 (flexible hose 50), and a scanning mechanism 6. Each of these components is housed in a housing 10 having a predetermined shape. In this embodiment, although the details will be described later, a circulating inkjet head that circulates and utilizes ink 9 between the ink tank 3 and the inkjet head 4 will be used as an example.

[0012] In addition, the scale of each component in the drawings used in this specification has been appropriately changed to make each component recognizable.

[0013] Here, printer 1 corresponds to one specific example of the "liquid jet recording device" in this disclosure, and inkjet head 4 (inkjet heads 4Y, 4M, 4C, 4K described later) corresponds to one specific example of the "liquid jet head" in this disclosure. In addition, ink 9 corresponds to one specific example of the "liquid" in this disclosure. Note that the "liquid" in this disclosure is not limited to ink 9 ("general image forming ink") described in this embodiment.

[0014] The transport mechanisms 2a and 2b, as shown in Figure 1, are mechanisms for transporting the recording paper P along the transport direction d (X-axis direction). These transport mechanisms 2a and 2b each have grid rollers 211 and 221, pinch rollers 212 and 222, and a drive mechanism (not shown). This drive mechanism rotates the grid rollers 211 and 221 around their axes (rotates them in the Z-X plane) and is composed of, for example, a motor.

[0015] (Ink Tank 3) The ink tank 3 is a tank that houses the ink 9. In this example, as shown in Figure 1, there are four types of ink tanks, each individually housing the four colors of ink 9: yellow (Y), magenta (M), cyan (C), and black (K). Specifically, there is an ink tank 3Y for the yellow ink 9, an ink tank 3M for the magenta ink 9, an ink tank 3C for the cyan ink 9, and an ink tank 3K for the black ink 9. These ink tanks 3Y, 3M, 3C, and 3K are arranged in a line along the X-axis within the housing 10.

[0016] Since ink tanks 3Y, 3M, 3C, and 3K have the same configuration except for the color of the ink 9 they contain, they will be collectively referred to as ink tank 3 below.

[0017] Figure 2 schematically shows an example of the general configuration of the inkjet head 4 and ink circulation mechanism 8 shown in Figure 1. As shown in Figures 1 and 2, the ink circulation mechanism 8 is a mechanism that circulates ink between the ink tank 3 and the inkjet head 4. Specifically, the ink circulation mechanism 8 includes a circulation channel 23 having an ink supply pipe 21 and an ink discharge pipe 22, a pressure pump 24 connected to the ink supply pipe 21, and a suction pump 25 connected to the ink discharge pipe 22.

[0018] The pressurizing pump 24 pressurizes the ink supply pipe 21 and sends ink 9 to the inkjet head 4 through the ink supply pipe 21. As a result, the ink supply pipe 21 side is under positive pressure relative to the inkjet head 4. The suction pump 25 reduces the pressure inside the ink discharge pipe 22 and sucks ink 9 from the inkjet head 4 through the ink discharge pipe 22. As a result, the ink discharge pipe 22 side is under negative pressure relative to the inkjet head 4. Driven by the pressurizing pump 24 and the suction pump 25, the ink 9 can circulate between the inkjet head 4 and the ink tank 3 through the circulation channel 23.

[0019] (Inkjet head 4) The inkjet head 4 is a head that records (prints) images, characters, etc. by spraying (discharging) droplet-shaped ink 9 onto the recording paper P from a plurality of nozzles (nozzle holes Hn), which will be described later. In this example, as shown in Figure 1, there are four types of inkjet heads, each spraying one of the four colors of ink 9 contained in the ink tanks 3Y, 3M, 3C, and 3K described above. Specifically, there is an inkjet head 4Y that sprays yellow ink 9, an inkjet head 4M that sprays magenta ink 9, an inkjet head 4C that sprays cyan ink 9, and an inkjet head 4K that sprays black ink 9. These inkjet heads 4Y, 4M, 4C, and 4K are arranged in a line along the Y-axis within the housing 10.

[0020] Note that inkjet heads 4Y, 4M, 4C, and 4K have the same configuration except for the color of the ink 9 they use, and therefore will be collectively referred to as inkjet head 4 below. A detailed example of the configuration of this inkjet head 4 will be described later (Figures 3 to 7).

[0021] The flexible hose 50 is a pipe (a pipe that constitutes the circulation channel 23 described above) for circulating and supplying ink 9 between the ink tank 3 and the inkjet head 4. This flexible hose 50 has, for example, a degree of flexibility that can follow the operation of the scanning mechanism 6 described below.

[0022] (Scanning mechanism 6) The scanning mechanism 6 is a mechanism that scans the inkjet head 4 along the width direction (Y-axis direction) of the recording paper P. As shown in Figure 1, the scanning mechanism 6 has a pair of guide rails 61a and 61b extending along the Y-axis direction, a carriage 62 movably supported on these guide rails 61a and 61b, and a drive mechanism 63 that moves the carriage 62 along the Y-axis direction.

[0023] The drive mechanism 63 includes a pair of pulleys 631a and 631b positioned between guide rails 61a and 61b, an endless belt 632 wound between these pulleys 631a and 631b, and a drive motor 633 that rotates the pulley 631a. Furthermore, the four types of inkjet heads 4Y, 4M, 4C, and 4K mentioned above are arranged in a line along the Y-axis direction on the carriage 62.

[0024] Furthermore, the scanning mechanism 6 and the transport mechanisms 2a and 2b described above constitute a moving mechanism that moves the inkjet head 4 and the recording paper P relative to each other. However, the moving mechanism is not limited to this type; for example, a method in which the inkjet head 4 is fixed while only the recording medium (recording paper P) is moved, thereby moving the inkjet head 4 and the recording medium relative to each other (a so-called "single-pass method") may also be used.

[0025] [B. Detailed Configuration of Inkjet Head 4] Next, a detailed example of the configuration of the inkjet head 4 will be described with reference to Figures 3 to 7, along with Figure 2 mentioned above.

[0026] Figure 3 is an exploded perspective view showing an example of the configuration of a head chip (head chip 40, described later) according to this embodiment. Figure 4 is a cross-sectional view corresponding to the line IV-IV in Figure 3, and Figure 5 is a cross-sectional view corresponding to the line V-V in Figure 3. Furthermore, Figure 6 is a cross-sectional view corresponding to the line VI-VI in Figure 4, and Figure 7 is a cross-sectional view corresponding to the line VII-VII in Figure 4.

[0027] (Head Chip 40) As shown in Figures 2 and 3, the inkjet head 4 comprises a head chip 40, an ink supply unit (not shown) connecting the ink circulation mechanism 8 and the head chip 40, and a drive unit 49. Furthermore, as shown in Figures 3 to 5, the head chip 40 is a so-called edge chute type that ejects ink 9 from the tip of the channel extending direction (Z-axis direction) of the ejection channel Ce, which will be described later, and is a circulating type (vertical circulation type) that circulates ink 9 with the ink tank 3. Note that this head chip 40 corresponds to one specific example of the "ejection unit" in this disclosure.

[0028] The head chip 40 comprises a first chip module 41A, a second chip module 41B, a return plate 42, and a nozzle plate (injection hole plate) 43. In the following description, the configurations of the first chip module 41A and the second chip module 41B will be described using the first chip module 41A as an example. Therefore, for components of the second chip module 41B that are the same as those of the first chip module 41A, the same reference numerals will be used as for the first chip module 41A, and their description may be omitted.

[0029] (First Chip Module 41A) The first chip module 41A comprises a first actuator plate 51, a first cover plate 52, and a first back plate 53. In the following description, the first chip module 41A will be described with the +Y axis side as the front side and the -Y axis side as the back side.

[0030] The first actuator plate 51 is a laminated substrate formed by stacking two piezoelectric substrates whose polarization directions differ in the thickness direction (Y-axis direction) (a so-called chevron type). The piezoelectric substrate is preferably a ceramic substrate made of, for example, PZT (lead zirconate titanate). However, the first actuator plate 51 may also be formed from a single piezoelectric substrate with a polarization direction set in one direction (a so-called monopole type).

[0031] The first actuator plate 51 has an ejection channel Ce for ejecting ink 9 (filled with ink 9) and a dummy channel (non-ejection channel) Cd that does not eject ink 9 (not filled with ink 9). The ejection channel Ce and the dummy channel Cd are arranged alternately on the first actuator plate 51 with spacing in the X-axis direction, thereby constituting a channel row 70. In this embodiment, a configuration in which the channel extension direction coincides with the Z-axis direction is described, but the channel extension direction may intersect with the Z-axis direction.

[0032] As shown in Figures 3 and 4, the discharge channel Ce terminates at its upper end within the first actuator plate 51, and its lower end opens at the lower end surface of the first actuator plate 51. The upper part of the discharge channel Ce gradually decreases in depth in the Y-axis direction as it extends upward. On the other hand, the lower part of the discharge channel Ce penetrates the first actuator plate 51 in the Y-axis direction. As shown in Figures 3 and 5, the dummy channel Cd penetrates the first actuator plate 51 in both the Y-axis direction and the Z-axis direction. The depth of the dummy channel Cd in the Y-axis direction is uniform over its entire length in the Z-axis direction. Such a discharge channel Ce corresponds to one specific example of a "pressure chamber" in this disclosure.

[0033] The portion of the first actuator plate 51 located between the discharge channel Ce and the dummy channel Cd each constitutes a drive wall Wd. Therefore, the discharge channel Ce is surrounded on both sides in the X-axis direction by the pair of drive walls Wd. The portion of the first actuator plate 51 located above the discharge channel Ce constitutes a tail portion 76.

[0034] As shown in Figure 3, the first actuator plate 51 has common wiring 81 and individual wiring 82 formed on it. The common wiring 81 and individual wiring 82 are formed by depositing electrode materials such as Ti / Au and Ni / Au into a film, for example, by vapor deposition, sputtering, or plating.

[0035] As shown in Figures 3 and 4, the common wiring 81 includes a common electrode Edc and a common terminal 85. The common electrode Edc is formed on the inner surfaces of the discharge channel Ce that face each other in the X-axis direction. In the illustrated example, the common electrode Edc is formed over the entire Y-axis direction on the inner surface of the discharge channel Ce.

[0036] The common terminals 85 are formed on the surface of the tail portion 76. The common terminals 85 are provided on the surface of the tail portion 76, corresponding to each discharge channel Ce. Each common terminal 85 extends linearly in the Z-axis direction above the corresponding discharge channel Ce. The lower end of the common terminal 85 is connected to the common electrode Edc.

[0037] As shown in Figures 3 and 5, the individual wiring 82 comprises individual electrodes Eda and individual terminals 88. The individual electrodes Eda are formed on the inner surfaces of each dummy channel Cd that face each other in the X-axis direction. In the illustrated example, the individual electrodes Eda are formed over the entire Y-axis direction on the inner surface of the dummy channel Cd.

[0038] The individual terminals 88 are formed on the surface of the tail portion 76 in a portion located above the common terminal 85. The individual terminals 88 are formed in a strip shape extending in the X-axis direction. The individual terminals 88 connect individual electrodes Eda that face each other in the X-axis direction with the discharge channel Ce in between, at the surface-side opening edge of dummy channels Cd that face each other in the X-axis direction with the discharge channel Ce in between. A partition groove 79 is formed in the tail portion 76 in a portion located between the common terminal 85 and the individual terminals 88. The partition groove 79 extends in the X-axis direction on the tail portion 76. The partition groove 79 separates the common terminal 85 and the individual terminals 88.

[0039] A flexible printed circuit board (not shown) is crimped onto the surface of the tail portion 76. The flexible printed circuit board is connected to a common terminal 85 and individual terminals 88 on the surface of the tail portion 76. The flexible printed circuit board connects the first chip module 41A and the drive unit 49, which will be described later.

[0040] (First cover plate 52) As shown in Figures 3 to 5, the first cover plate 52 is bonded to the surface of the first actuator plate 51. Specifically, the first cover plate 52 closes the surface openings of the discharge channel Ce and the dummy channel Cd, respectively, while exposing the surface of the tail portion 76. The lower end surface of the first cover plate 52 is positioned flush with the lower end surface of the first actuator plate 51.

[0041] In the first cover plate 52, a common ink chamber 90 is formed at a position that overlaps with the upper part of the discharge channel Ce when viewed from the Y-axis direction. The common ink chamber 90 extends in the X-axis direction with a length that spans, for example, the channel row 70, and opens on the surface of the first cover plate 52. In the common ink chamber 90, which is indirectly in contact with the ink supply pipe 21 through an inlet port (not shown), a slit 91 is formed at a position that overlaps with the discharge channel Ce when viewed from the Y-axis direction. The slit 91 communicates separately between the upper part of each discharge channel Ce and the inside of the common ink chamber 90. Therefore, the common ink chamber 90 communicates with each discharge channel Ce through each slit 91, but does not communicate with each dummy channel Cd.

[0042] (First backplate 53) The first backplate 53 is bonded to the back surface of the first actuator plate 51. The first backplate 53 has the same outer shape as the first actuator plate 51 when viewed from the Y-axis direction. The first backplate 53 is superimposed on the entire first actuator plate 51 when viewed from the Y-axis direction. That is, the first backplate 53 closes the back side openings of the discharge channel Ce and the dummy channel Cd, respectively.

[0043] (Second Chip Module 41B) The second chip module 41B includes a second actuator plate 101, a second cover plate 102, and a second back plate (flow channel plate) 103. In the second chip module 41B, the second back plate 103, the second actuator plate 101, and the second cover plate 102 are stacked in order from the +Y axis side to the -Y axis side. The second chip module 41B is stacked on the first chip module 41A with the surface side (-Y axis side) facing the opposite side to the first chip module 41A. Specifically, the first chip module 41A and the second chip module 41B are integrated by joining the back surfaces of the first back plate 53 and the second back plate 103 to each other. In this case, the lower end surfaces of the first chip module 41A and the second chip module 41B are arranged flush with each other.

[0044] The discharge channels Ce and dummy channels Cd of the second chip module 41B are each arranged with a half-pitch shift with respect to the arrangement pitch of the discharge channels Ce and dummy channels Cd of the first chip module 41A. That is, the discharge channels Ce and the dummy channels Cd of the first chip module 41A and the second chip module 41B are arranged in a staggered pattern. In this case, the discharge channel Ce of the first chip module 41A faces the dummy channel Cd of the second chip module 41B in the Y-axis direction, and the dummy channel Cd of the first chip module 41A faces the discharge channel Ce of the second chip module 41B in the Y-axis direction. Note that the pitches of the discharge channels Ce and the dummy channels Cd in the first chip module 41A and the second chip module 41B can be appropriately changed.

[0045] (Return plate 42) The return plate 42 is bonded together to the lower end faces of the first chip module 41A and the second chip module 41B. The return plate 42 closes the lower end openings of the discharge channel Ce and the dummy channel Cd, respectively. The return plate 42 is made of, for example, polyimide. Multiple first communication passages 110 and multiple second communication passages 111 are formed in the return plate 42.

[0046] As shown in Figures 4 to 6, the multiple first communication passages 110 are each formed separately at the same position in the X-axis direction as each ejection channel Ce in the first chip module 41A. In this embodiment, the multiple first communication passages 110 are formed at intervals in the X-axis direction corresponding to the arrangement pitch of the ejection channels Ce. Specifically, each first communication passage 110 penetrates the return plate 42 in the Z-axis direction and extends linearly in the Y-axis direction. The +Y-axis end of the first communication passage 110 overlaps with at least the ejection channel Ce when viewed from the Z-axis direction. That is, the first communication passage 110 communicates with the ejection channel Ce of the first chip module 41A. In the illustrated example, the first communication passage 110 overlaps with the entire Y-axis direction of the first actuator plate 51 when viewed from the Z-axis direction. The first communication passage 110 may also extend to a position where it overlaps with the first cover plate 52 when viewed from the Z-axis direction.

[0047] The -Y-axis end of the first connecting passage 110 overlaps with the first backplate 53 when viewed from the Z-axis direction. Specifically, the first connecting passage 110 extends over the entire Y-axis area of ​​the first backplate 53 when viewed from the Z-axis direction. However, the first connecting passage 110 may extend to a position where it overlaps with the second backplate 103 when viewed from the Z-axis direction.

[0048] The plurality of second communication passages 111 are respectively formed at positions equivalent in the X-axis direction to each discharge channel Ce in the second chip module 41B. In the present embodiment, a plurality of second communication passages 111 are formed at intervals in the X-axis direction corresponding to the arrangement pitch of the discharge channels Ce of the second chip module 41B. That is, the first communication passage 110 and the second communication passages 111 are alternately arranged at intervals in the X-axis direction. Each second communication passage 111 penetrates the feedback plate 42 in the Z-axis direction and extends linearly in the Y-axis direction. The -Y-axis side end portion in the second communication passage 111 overlaps at least the discharge channel Ce when viewed from the Z-axis direction. That is, the second communication passage 111 communicates with the discharge channel Ce of the second chip module 41B. In the illustrated example, the second communication passage 111 overlaps the entire Y-axis direction in the second actuator plate 101 when viewed from the Z-axis direction. Note that the second communication passage 111 may extend to a position overlapping the second cover plate 102 when viewed from the Z-axis direction.

[0049] The +Y-axis side end portion in the second communication passage 111 overlaps the second back plate 103 when viewed from the Z-axis direction. Specifically, the second communication passage 111 extends over the entire Y-axis direction in the second back plate 103 when viewed from the Z-axis direction. However, the second communication passage 111 may extend to a position overlapping the first back plate 53 when viewed from the Z-axis direction.

[0050] The dimensions in the X-axis direction of the first communication passage 110 and the second communication passages 111 are uniform over the entire Y-axis direction. The dimensions in the X-axis direction of the first communication passage 110 and the second communication passages 111 are smaller than the dimensions in the X-axis direction of the discharge channel Ce. However, the dimensions in the X-axis direction of the first communication passage 110 and the second communication passages 111 may be equal to or greater than the dimensions in the X-axis direction of the discharge channel Ce. Note that the dimensions in the X-axis direction of the first communication passage 110 may gradually change as going in the Y-axis direction.

[0051] (Nozzle Plate 43) As shown in Figures 3 to 5, the nozzle plate 43 is joined to the lower end surface of the return plate 42. The nozzle plate 43 has a plurality of nozzle holes Hn (nozzle holes Hn1 and nozzle holes Hn2) arranged in the direction of the Z axis. These nozzle holes Hn (Hn1, Hn2) each correspond to a specific example of a "nozzle" in this disclosure.

[0052] Multiple nozzle holes Hn1 are individually formed on the nozzle plate 43 at positions that overlap with each first communication passage 110 when viewed from the Z-axis direction. That is, the nozzle holes Hn1 are arranged at the same pitch as the first communication passages 110 and spaced apart in the X-axis direction. The nozzle holes Hn1 communicate with the corresponding discharge channel Ce of the first chip module 41A through the corresponding first communication passage 110. Specifically, each nozzle hole Hn1 is formed at the +Y-axis end of each first communication passage 110 at a position that overlaps with the discharge channel Ce and the first communication passage 110 when viewed from the Z-axis direction. Note that the nozzle holes Hn1 may also communicate with the first communication passage 110 at a position offset in the Y-axis direction from the discharge channel Ce of the first chip module 41A.

[0053] Multiple nozzle holes Hn2 are individually formed on the nozzle plate 43 at positions that overlap with each second communication passage 111 when viewed from the Z-axis direction. That is, the nozzle holes Hn2 are arranged at the same pitch as the second communication passages 111 and spaced apart in the X-axis direction. The nozzle holes Hn2 communicate with the corresponding discharge channel Ce of the second chip module 41B through the corresponding second communication passage 111. Specifically, each nozzle hole Hn2 is formed at the -Y-axis end of each second communication passage 111 at a position that overlaps with the discharge channel Ce and the second communication passage 111 when viewed from the Z-axis direction. Note that the nozzle holes Hn2 may also communicate with the second communication passage 111 at a position offset in the Y-axis direction from the discharge channel Ce of the second chip module 41B.

[0054] Here, as shown in Figures 4, 5, and 7, the first backplate 53 and the second backplate 103 constitute the flow path plate 120 of this embodiment. The flow path plate 120 has a plurality of first connection passages 121, a plurality of second connection passages 122, and a manifold 123 formed therein.

[0055] Multiple first connection passages 121, together with their corresponding first connecting passages 110, constitute a first return passage. Each of the multiple first connection passages 121 is formed separately at a position that overlaps with the -Y-axis end of the corresponding first connecting passage 110 when viewed from the Z-axis direction. The first connection passages 121 are arranged at the same pitch as the first connecting passages 110, with spacing in the X-axis direction. The first connection passages 121 communicate with their corresponding first connecting passages 110. Specifically, the first connection passages 121 open on the back surface of the first back plate 53. The back surface opening of the first connection passage 121 is closed by the second back plate 103.

[0056] The first connecting passage 121 extends linearly in the Z-axis direction when viewed from the Y-axis direction. The lower end of the first connecting passage 121 opens on the lower end surface of the first back plate 53. As a result, the lower end opening of the first connecting passage 121 communicates with the first connecting passage 110. On the other hand, the upper end of the first connecting passage 121 terminates within the first back plate 53. The upper end of the first connecting passage 121 is preferably located below the upper end of the discharge channel Ce, and in the illustrated example, it is located at the same height as the lower end edge of the slit 91. In this embodiment, the Z-axis dimension T1 of the first connecting passage 121 (see Figure 4) is greater than the Y-axis dimension T2 of the first connecting passage 110. In this embodiment, the dimension T2 of the first connecting passage 110 is the distance between the lower end opening of the discharge channel Ce and the lower end opening of the first connecting passage 121. However, the dimension T1 in the Z-axis direction of the first connecting passage 121 may be less than or equal to the dimension T2 in the Y-axis direction of the first connecting passage 110. The first connecting passage 121 may extend in a direction that intersects the Z-axis direction when viewed from the X-axis direction, or it may extend in a curved shape.

[0057] The lower end opening of the first connecting passage 121 has a different dimension in the X-axis direction compared to the connection portion with the first connecting passage 121 at the -Y-axis end of the first connecting passage 110 (hereinafter referred to as the downstream connecting opening). As shown in Figure 6, the dimension Q1 in the X-axis direction at the lower end opening of the first connecting passage 121 is larger than the dimension Q2 in the X-axis direction at the downstream connecting opening of the first connecting passage 110. In this case, it is preferable that the downstream connecting opening of the first connecting passage 110 is located inward in the Y-axis direction relative to the lower end opening of the first connecting passage 121 when viewed from the Z-axis direction. However, the X dimension of the lower end opening of the first connecting passage 121 may be smaller than that of the downstream connecting opening of the first connecting passage 110. In the illustrated example, the dimension Q2 of the downstream connecting opening is equivalent to the dimension in the X-axis direction of the first connecting passage 110.

[0058] Furthermore, the first connecting passage 121 has a gradually decreasing flow path cross-sectional area (cross-sectional area perpendicular to the Z-axis direction) as it moves from the lower end opening (upstream opening) to the upper end opening (downstream opening). Specifically, the dimensions of the first connecting passage 121 in the Y-axis direction gradually decrease as it moves from bottom to top. However, the dimensions of the first connecting passage 121 in the X-axis direction may also decrease as it moves from bottom to top. In addition, the flow path cross-sectional area of ​​the first connecting passage 121 may be uniform throughout the entire Z-axis direction.

[0059] Multiple second connection paths 122, together with their corresponding second connecting passages 111, constitute a second return path. Each of the multiple second connection paths 122 is formed separately at a position that overlaps with the +Y-axis end of each second connecting passage 111 when viewed from the Z-axis direction. The second connection paths 122 are arranged at the same pitch as the second connecting passages 111, with spacing in the X-axis direction. That is, the first connection paths 121 and the second connection paths 122 are arranged alternately in the X-axis direction.

[0060] Each second connecting passage 122 communicates with the corresponding second connecting passage 111. Specifically, the second connecting passage 122 opens on the back surface (the surface facing the +Y axis) of the second back plate 103. The back surface opening of the second connecting passage 122 is closed by the first back plate 53. The second connecting passage 122 extends in the Z-axis direction. The lower end of the second connecting passage 122 opens on the lower end surface of the second back plate 103. As a result, the lower end opening of the second connecting passage 122 communicates with the second connecting passage 111. On the other hand, the upper end of the second connecting passage 122 terminates within the second back plate 103. The dimensions of the second connecting passage 122 can be set in the same way as the first connecting passage 121.

[0061] The manifold 123 is formed in the flow path plate 120 in the portion located above the first connection passage 121 and the second connection passage 122. The manifold 123 is formed by overlapping a first recess 123a formed in the first back plate 53 and a second recess 123b formed in the second back plate 103. The first recess 123a is a recess that opens on the back surface of the first back plate 53 and extends in the Z-axis direction and the Y-axis direction. The second recess 123b is a recess that opens on the back surface of the second back plate 103 and extends in the Z-axis direction and the Y-axis direction. The manifold 123 is formed by the back-side openings of the first recess 123a and the second recess 123b communicating with each other. In the illustrated example, the dimensions of the first recess 123a and the second recess 123b are the same. However, the dimensions of the first recess 123a and the second recess 123b may be different. Furthermore, the manifold 123 may be configured such that a recess formed on only one of the back plates, the first back plate 53 or the second back plate 103, is closed by the back surface of the other back plate.

[0062] The manifold 123 has both a first connection passage 121 and a second connection passage 122 connected to it. Specifically, the upper end opening of each first connection passage 121 opens on the lower end surface of the first recess 123a. The upper end opening of each second connection passage 122 opens on the lower end surface of the second recess 123b. The manifold 123 is indirectly connected to the ink discharge pipe 22 through an outlet port (not shown).

[0063] Here, the aforementioned common ink chamber 90 (supply-side common flow path Rin) corresponds to one specific example of the "liquid supply flow path" in this disclosure. On the other hand, the manifold 123 (recovery-side common flow path Rout) described above corresponds to one specific example of the "liquid recovery flow path" in this disclosure. Furthermore, these supply-side common flow path Rin and recovery-side common flow path Rout each correspond to one specific example of the "common flow path" in this disclosure. As will be described in detail later, in the inkjet head 4 of this embodiment, the pressure loss on the recovery-side common flow path Rout is greater than the pressure loss on the supply-side common flow path Rin.

[0064] (Drive Unit 49) As shown in Figure 2, the drive unit 49 drives the ejection of ink 9 using a drive signal Sd (drive voltage Vd). In this case, the drive unit 49 outputs such a drive signal Sd (drive voltage Vd) based on various data (signals) supplied from the print control unit (not shown) inside the printer 1 (inside the inkjet head 4).

[0065] Furthermore, the drive unit 49 drives the actuator plates (the first actuator plate 51 and the second actuator plate 101 described above) to perform ejection so that the ink 9 filled in the ejection channel Ce is ejected from the nozzle holes Hn (see Figure 2). Specifically, the drive unit 49 applies the above-mentioned drive voltage Vd (drive signal Sd) to the actuator plates to expand and contract the ejection channel Ce, thereby causing the ink 9 to be ejected from each nozzle hole Hn (performing an ejection operation).

[0066] [C. Detailed Configuration of Drive Voltage Vd and Drive Signal Sd] Next, with reference to Figures 8 to 10, a detailed configuration example of the drive voltage Vd and drive signal Sd described above will be explained.

[0067] Figure 8 schematically illustrates an example of the supply path for each potential supplied from the drive unit 49 to the drive electrode Ed (the individual electrode Eda and common electrode Edc mentioned above). Specifically, Figure 8 shows an example of the supply path for the potential supplied to the individual electrode Eda (individual potential Vda) and the potential supplied to the common electrode Edc (common potential Vdc) with respect to the channel array 70 (discharge channel Ce and dummy channel Cd).

[0068] Figure 9 schematically represents an example waveform of the drive signal Sd using a timing diagram. Figure 10 schematically represents various waveform examples of the drive signal Sd using timing diagrams.

[0069] In both Figures 9 and 10, the vertical axis represents the voltage value of the drive voltage Vd (corresponding to the potential difference between the individual potential Vda and the common potential Vdc: Vd = Vda - Vdc), and the horizontal axis represents time t. The magnitude of this drive voltage Vd corresponds to the volume of the discharge channel Ce described above. A positive (+) value for the drive voltage Vd and a negative (-) value indicate that the volume is expanded or contracted beyond the reference value, respectively (see Figure 9).

[0070] Incidentally, in the example shown in Figure 9, the common potential Vdc is set to a predetermined positive potential (Vdc > 0) so that the drive voltage Vd (the potential difference between the individual potential Vda and the common potential Vdc) is set to a negative value (Vd < 0), but this example is not the only one. That is, for example, the common potential Vdc can be set to 0 (ground potential), and the individual potential Vda can be set to a predetermined negative potential (Vda < 0) so that the drive voltage Vd is directly set to a negative value (Vd < 0). Even in such a case, it is possible to perform the same drive as in the example shown in Figure 9. Note that in the example shown in Figure 9, the drive voltage Vd is set to both a positive and a negative value, but for example, the drive voltage Vd can be set to only a positive or negative value.

[0071] In the examples shown in Figures 9 and 10(A) to 10(D), the drive signal Sd is a signal having multiple pulses (pulses p1, p2) within one cycle (printing cycle Tp, which will be described below) (a signal to which the so-called "multi-pulse method" is applied). Pulse p1 is a pulse for expanding the volume of the ejection channel Ce (expansion pulse), and pulse p2 is a pulse for contracting the volume of the ejection channel Ce (contraction pulse). In the examples shown in Figures 10(A) to 10(D), among the multiple pulses within one cycle (printing cycle Tp), the first pulse is pulse p1 and the last pulse is pulse p2. However, the first pulse within the printing cycle Tp may be either pulse p1 (expansion pulse) or pulse p2 (contraction pulse). Furthermore, the drive signal Sd may be configured so that only one pulse (pulses p1, p2) is provided within the printing cycle Tp.

[0072] The "one cycle (=printing cycle Tp)" mentioned above refers to the time interval required to form one pixel (dot) on the recording paper P (recording medium). Furthermore, the printing frequency fp in the drive signal Sd shown in Figures 10(A) to 10(D) is the reciprocal of this printing cycle Tp (fp = 1 / Tp). In other words, this printing frequency fp corresponds to the number of pixels (dots) formed per second on the recording paper P (recording medium).

[0073] In this embodiment, as will be described in detail later, the following are included as multiple pulses in the drive signal Sd described above. Specifically, the drive signal Sd includes one or more ejection pulses Pj having a pulse width Wj that corresponds to the range (degree) in which ink 9 is ejected from the nozzle hole Hn. This ejection pulse Pj corresponds to the collection of pulses p1 and p2 described above, as will be described in detail later. Furthermore, in a predetermined case described later, the drive signal Sd includes one or more non-ejection pulses (micro-vibration pulses) Pb that have a pulse width Wb that corresponds to the range (degree) in which ink 9 is not ejected from the nozzle hole Hn, and that cause the meniscus to vibrate slightly, as will be described later.

[0074] Incidentally, the pulse width Wb in the range where ink 9 is not ejected from the nozzle hole Hn is, for example, about 1 / 6 to 1 / 3 of the resonant period (AP: Acoustic Period). In other words, a range for the pulse width Wb is, for example, (AP / 6) ≤ Wb ≤ (AP / 3). On the other hand, the pulse width Wj in the range where ink 9 is ejected from the nozzle hole Hn is, for example, a range that is larger than the pulse width Wb mentioned above. In other words, a range for the pulse width Wj is, for example, (AP / 3) < Wj.

[0075] The AP mentioned above corresponds to a period of half the natural vibration period of the ink 9 within the ejection channel Ce (1 AP = (natural vibration period of ink 9) / 2). When the pulse width of a certain pulse is set to AP, the ejection speed (ejection efficiency) of the ink 9 is maximized when ejecting a normal single drop of ink 9 (single drop ejection). Furthermore, this AP is determined by, for example, the shape of the ejection channel Ce and the physical properties of the ink 9 (specific gravity, etc.).

[0076] Details of these discharge pulses Pj and non-discharge pulses Pb will be described later (Figures 15 and 16).

[0077] [Operation and Effects] (A. Basic Operation of Printer 1) In this printer 1, the recording operation (printing operation) of images, characters, etc. on the recording paper P is performed as follows. Initially, the four types of ink tanks 3 (3Y, 3M, 3C, 3K) shown in Figure 1 are each sufficiently filled with the corresponding color (four colors) of ink 9. The ink 9 in the ink tanks 3 is filled into the inkjet head 4 via the flexible hose 50.

[0078] In this initial state, when the printer 1 is activated, the grid rollers 211 and 221 in the transport mechanisms 2a and 2b rotate, respectively, and the recording paper P is transported between the grid rollers 211 and 221 and the pinch rollers 212 and 222 along the transport direction d (X-axis direction). Simultaneously with this transport operation, the drive motor 633 in the drive mechanism 63 rotates the pulleys 631a and 631b respectively, thereby operating the endless belt 632. As a result, the carriage 62 moves back and forth along the width direction (Y-axis direction) of the recording paper P, guided by the guide rails 61a and 61b. At this time, the inkjet heads 4 (4Y, 4M, 4C, 4K) appropriately eject four colors of ink 9 onto the recording paper P, thereby recording images, characters, etc., onto the recording paper P.

[0079] (B. Detailed operation of inkjet head 4) Next, we will explain the detailed operation of inkjet head 4.

[0080] In this inkjet head 4, in the aforementioned vertically circulating head chip 40, the pressurizing pump 24 and suction pump 25 shown in Figure 2 are first activated to circulate ink 9 in the circulation channel 23. In this case, the ink 9 circulating in the ink supply pipe 21 flows through the inlet port into the common ink chambers 90 of the first chip module 41A and the second chip module 41B. The ink 9 that has flowed into each common ink chamber 90 is supplied to each ejection channel Ce through the slit 91. The ink 9 that has flowed into each ejection channel Ce is collected in the manifold 123 through the first communication passage 110 and the second communication passage 111, and the first connection passage 121 and the second connection passage 122, and then discharged to the ink discharge pipe 22 through the outlet port. The ink 9 discharged to the ink discharge pipe 22 is returned to the ink tank 3 and then supplied again to the ink supply pipe 21. This circulates the ink 9 between the inkjet head 4 and the ink tank 3.

[0081] Then, when the carriage 62 starts reciprocating, the aforementioned drive voltage Vd is applied to the drive electrodes Ed (individual electrodes Eda and common electrode Edc) via the flexible substrate. As a result, thickness sliding deformation occurs in the two drive walls Wd that define the discharge channel Ce, and these two drive walls Wd deform so that they protrude toward the dummy channel Cd. In other words, in the actuator plates of this embodiment (first actuator plate 51 and second actuator plate 101), two piezoelectric substrates that have been polarized in the thickness direction (Y-axis direction) are stacked. Therefore, when the drive voltage Vd is applied, the drive walls Wd bend in a V-shape around an intermediate position in the Y-axis direction. As a result, the discharge channel Ce deforms as if it were bulging.

[0082] As the volume of the ejection channel Ce increases due to the deformation of the two drive walls Wd, the ink 9 in the common ink chamber 90 is guided into the ejection channel Ce through the slit 91. The ink 9 guided into the ejection channel Ce then propagates as a pressure wave, and when this pressure wave reaches the nozzle holes Hn (Hn1, Hn2), the drive voltage Vd applied to each drive electrode Ed is set to 0 (zero). As a result, the drive walls Wd return to their original state, and the volume of the ejection channel Ce, which had increased, returns to its original volume. This operation increases the pressure inside the ejection channel Ce, pressurizing the ink 9. As a result, the ink 9 can be ejected from the nozzle holes Hn. At this time, as the ink 9 passes through the nozzle holes Hn, it is ejected as droplet-shaped ink droplets. This allows characters, images, etc. to be recorded on the recording paper P as described above. In other words, in the head chip 40 of this embodiment, a portion of the ink 9 flowing through the first communication passage 110 and the second communication passage 111 is ejected through the nozzle hole Hn. Meanwhile, the remaining ink 9 is returned to the manifold 123 through the first connection passage 121 and the second connection passage 122.

[0083] (C. Non-discharge drive using non-discharge pulse Pb) Next, the non-discharge drive using the non-discharge pulse Pb described above in this embodiment (a non-discharge drive that causes minute vibrations of the meniscus, which will be described later) will be explained in detail.

[0084] (C-1. Challenges in Inkjet Heads) First, inkjet heads with a common flow path generally have the following challenges. That is, at the ejection timing that includes both nozzle holes Hn from which ink 9 is ejected (ejection nozzle Hnj) and nozzle holes Hn from which ink 9 is not ejected (non-ejection nozzle Hnn) among multiple nozzle holes Hn, the ejection stability of ink 9 may decrease as follows.

[0085] Figures 11 and 12 schematically illustrate examples of ink 9 discharge patterns from multiple nozzle holes Hn, respectively. Figure 13 is a schematic diagram illustrating the incorporation of air bubbles Ab into the non-discharge nozzle Hnn described above. For convenience, in Figures 11 to 13 (and Figure 14 described later), the supply-side common flow path Rin and the recovery-side common flow path Rout are shown together.

[0086] First, as shown in Figure 11, for example, in an inkjet head 4 having a common flow path (supply-side common flow path Rin and recovery-side common flow path Rout), when all of the multiple nozzle holes Hn are ejection nozzles Hnj at the ejection timing, the following occurs. That is, droplets of ink 9 are ejected from each ejection nozzle Hnj at the same timing, and the positions of the droplets at a given time are aligned among the ejection nozzles Hnj, thus ensuring the ejection stability of the ink 9.

[0087] On the other hand, as shown in Figure 12, for example, when some of the multiple nozzle holes Hn are non-eject nozzles Hnn (both eject nozzles Hnj and non-eject nozzles Hnn exist), the following problems may occur if a conventional drive method is used. Specifically, firstly, as in the inkjet head 4 of this embodiment, if the pressure loss on the recovery side common channel Rout is greater than the pressure loss on the supply side common channel Rin, it is necessary to increase the suction pressure from the output side (recovery side). In that case, the discharge pressure of the ink 9 by the eject nozzle Hnj increases, causing the pressure in the ejection channel Ce, which communicates with the non-eject nozzle Hnn via the common channel, to become a negative pressure exceeding the meniscus resistance (pressure value Pmb, described later), and the meniscus is destroyed. When the meniscus is destroyed in this way, for example, as shown in Figure 12, air bubbles Ab are mixed into the common channel from the location of the non-eject nozzle Hnn, causing fluctuations in the liquid ejection speed and droplet volume. Specifically, as shown by the symbol P9 in Figure 12, for example, in multiple ejection nozzles Hnj and non-ejection nozzles Hnn, the ejected ink droplets 9 change position in a wavy manner, resulting in a decrease in the ejection stability of the ink 9.

[0088] Furthermore, such meniscus disruption and the inclusion of air bubbles Ab are more likely to occur, for example, when, along the arrangement direction (X-axis direction) of the multiple ejection channels Ce, a non-ejection nozzle Hnn and at least an adjacent nozzle hole Hn become an ejection nozzle Hnj, as shown in Figure 13. This is because, when ink 9 is being ejected at an ejection nozzle Hnj adjacent to a non-ejection nozzle Hnn, air bubbles Ab are more easily drawn into that non-ejection nozzle Hnn (see the location indicated by the symbol Pn1 in Figure 13).

[0089] (C-2. Driving method of this embodiment) In this embodiment, as described above, when the ejection timing includes both the ejection nozzle Hnj and the non-ejection nozzle Hnn in the multiple nozzle holes Hn, a non-ejection drive is performed using the non-ejection pulse Pb described above. Specifically, only this non-ejection pulse Pb (a pulse having a pulse width Wb in the range in which ink 9 is not ejected from the nozzle hole Hn, and a pulse that causes the meniscus described above to vibrate slightly) is included in the drive signal Sd, and a non-ejection drive is performed for the non-ejection nozzle Hnn.

[0090] Figure 14 is a schematic diagram illustrating the minute vibrations caused by non-ejection drive according to this embodiment (the minute vibrations to the meniscus described above). In this embodiment, for example, as shown in Figure 14, a drive signal Sd containing only the non-ejection pulse Pb described above is used to cause minute vibrations in the meniscus in the ejection channel Ce, which communicates with the non-ejection nozzle Hnn via a common flow path (see the solid arrow in the area indicated by the reference numeral Pn2 in Figure 14). When the meniscus is vibrating minutely in this way, it becomes less likely to be damaged even when the pressure on the meniscus is higher than in the static state. As a result, even at ejection timings that include the non-ejection nozzle Hnn, droplets of ink 9 are ejected at the same timing from multiple ejection nozzles Hnj and non-ejection nozzles Hnn, respectively, as in the case of Figure 11 described above, and the ejection stability of ink 9 is ensured.

[0091] Here, Figure 15 shows an example of discharge drive and non-discharge drive according to this embodiment. Figure 16 schematically shows an example of the drive signal Sd during discharge drive for the discharge nozzle Hnj shown in Figure 15 (Figure 16(A)) and non-discharge drive for the non-discharge nozzle Hnn (Figure 16(B)), as shown in timing diagrams. Figure 17 schematically shows an example of the pressure waves Pwj and Pwn corresponding to the discharge nozzle Hnj and non-discharge nozzle Hnn, as shown in timing diagrams.

[0092] In Figures 16(A) and (B), the vertical axis represents the voltage value of the drive voltage Vd, and the horizontal axis represents time t. In Figure 17, the vertical axis represents pressure, and the horizontal axis represents time t. Also, in the example of the discharge pulse Pj shown in Figure 16(A), for convenience, multiple pulses (the aforementioned pulses p1 and p2) are shown together.

[0093] First, as shown in Figure 15, in this embodiment, discharge driving for the discharge nozzle Hnj and non-discharge driving for the non-discharge nozzle Hnn are performed as follows. That is, as described above, the drive unit 49 performs such discharge driving and non-discharge driving when the discharge timing includes both the discharge nozzle Hnj and the non-discharge nozzle Hnn in the plurality of nozzle holes Hn.

[0094] Specifically, as shown in Figure 16(A), for example, when driving the ejection nozzle Hnj, the drive signal Sd includes one or more ejection pulses Pj having the aforementioned pulse width Wj (pulse width of the range in which ink 9 is ejected) within the printing cycle Tp. In the example of Figure 16(A), one ejection pulse Pj is included within the printing cycle Tp in the drive signal Sd.

[0095] On the other hand, as shown in Figure 16(B), for example, when driving a non-eject nozzle Hnn without ejecting, the drive signal Sd contains only one or more non-eject pulses Pb having the aforementioned pulse width Wb (pulse width in the range where ink 9 is not ejected) within the printing cycle Tp. In this example of Figure 16(B), multiple eject pulses Pj are included within the printing cycle Tp in the drive signal Sd.

[0096] Furthermore, as shown in Figure 15, the drive unit 49 performs a non-discharge drive for the non-discharge nozzles Hnn when the number of discharge nozzles Hnj is greater than the number of non-discharge nozzles Hnn. This is because the meniscus rupture and the inclusion of air bubbles Ab mentioned above are more likely to occur as the number of non-discharge nozzles Hnn approaches zero, so it is desirable to perform such a non-discharge drive when the number of non-discharge nozzles Hnn is relatively small.

[0097] Furthermore, it is desirable that the drive unit 49 perform a non-discharge drive on the non-discharge nozzle Hnn when, along the arrangement direction of the multiple discharge channels Ce, at least the nozzle holes Hn adjacent to the non-discharge nozzle Hnn become discharge nozzles Hnj (see the examples in Figures 13 and 14 mentioned above). This is because, as mentioned above, meniscus rupture and the incorporation of air bubbles Ab are more likely to occur when such discharge timings occur.

[0098] Furthermore, regarding the pressure wave Pwj in the discharge channel Ce that communicates with the discharge nozzle Hnj via a common flow path, and the pressure wave Pwn in the discharge channel Ce that communicates with the non-discharge nozzle Hnn via a common flow path, as shown in Figure 17, it is desirable that the non-discharge drive be performed after setting them as follows, for example. That is, as shown in the example in Figure 17, it is desirable that the drive unit 49 perform a non-discharge drive for the non-discharge nozzle Hnn such that the phases of these pressure waves Pwj and Pwn do not coincide with each other. This makes it even less likely for the meniscus to break and for air bubbles Ab to be mixed in as described above. The pressure value Pmb shown in Figure 17 is the pressure value corresponding to the meniscus resistance mentioned above.

[0099] (D. Operation and Effects) In this embodiment, when a discharge timing occurs in which both a discharge nozzle Hnj and a non-discharge nozzle Hnn are included in a plurality of nozzle holes Hn (nozzles), only the aforementioned non-discharge pulse Pb is included in the drive signal Sd, thereby performing a non-discharge drive for the non-discharge nozzle Hnn.

[0100] As a result, the meniscus in the ejection channel Ce, which communicates with the non-ejection nozzle Hnn via a common channel, vibrates slightly. This prevents the pressure in the ejection channel Ce from exceeding the meniscus's resistance and causing the meniscus to break. Therefore, in a configuration including a common channel (supply-side common channel Rin and recovery-side common channel Rout), the incorporation of air bubbles Ab from the non-ejection nozzle Hnn into the common channel is prevented, and fluctuations in the ink ejection speed and droplet volume are reduced. As a result, in this embodiment, it is possible to improve the ejection stability of the ink 9.

[0101] Furthermore, in this embodiment, if non-discharge driving is performed for non-discharge nozzles Hnn at a discharge timing when the number of discharge nozzles Hnj is greater than the number of non-discharge nozzles Hnn, the following occurs. Specifically, as mentioned above, the destruction of the meniscus and the inclusion of air bubbles Ab become more likely to occur as the number of non-discharge nozzles Hnn approaches zero. Therefore, by performing the non-discharge driving described above when the number of non-discharge nozzles Hnn is relatively small, the destruction of the meniscus and the inclusion of air bubbles Ab become even less likely to occur. As a result, fluctuations in the discharge speed and droplet volume of ink 9 are further reduced, making it possible to further improve the discharge stability of ink 9.

[0102] Furthermore, in this embodiment, if, along the arrangement direction (X-axis direction) of the multiple ejection channels Ce, at least the nozzle holes Hn adjacent to the non-ejection nozzle Hnn become ejection nozzles Hnj at the ejection timing, then the following occurs. That is, when such an ejection timing occurs, as mentioned above, meniscus destruction and the incorporation of air bubbles Ab are likely to occur. Therefore, by performing the non-ejection drive described above at that ejection timing, meniscus destruction and the incorporation of air bubbles Ab become even less likely to occur. As a result, fluctuations in the ejection speed and droplet volume of the ink 9 are further reduced, and the ejection stability of the ink 9 can be further improved.

[0103] In addition, in this embodiment, if non-discharge driving is performed for the non-discharge nozzle Hnn such that the phases of the aforementioned pressure waves Pwj and Pwn do not coincide in the discharge channel Ce that communicates with the discharge nozzle Hnj via a common flow path and in the discharge channel Ce that communicates with the non-discharge nozzle Hnn via a common flow path, the following occurs. That is, as described above, meniscus destruction and the mixing of air bubbles Ab become even less likely to occur, resulting in further reduction of fluctuations in the discharge speed and droplet volume of the ink 9, and thus further improvement in the discharge stability of the ink 9.

[0104] <2. Modifications> The present disclosure has been described above with reference to embodiments, but the present disclosure is not limited to these embodiments, and various modifications are possible.

[0105] For example, in the above embodiment, specific examples of the configuration (shape, arrangement, number, etc.) of each component in the printer and inkjet head were given and explained, but the configuration is not limited to those described in the above embodiment, and other shapes, arrangements, numbers, etc. may be used. Also, the values, ranges, and magnitude relationships of the various parameters described in the above embodiment are not limited to those described in the above embodiment, and other values, ranges, and magnitude relationships may be used.

[0106] Specifically, in the above embodiment, for example, examples of the types and number of pulses included in the drive signal Sd, the magnitude of the drive voltage Vd and various frequencies, and the pulse width setting values ​​were specifically described, but the embodiment is not limited to those described above.

[0107] Furthermore, various types of inkjet head structures can be applied. That is, in the above embodiment, for example, an edge-chute type inkjet head, which ejects ink 9 along the extending direction of each ejection channel in the actuator plate, was described as an example. However, it is not limited to this example, and for example, a side-chute type inkjet head, which ejects ink 9 from the central part in the extending direction of each ejection channel, may also be used. Also, in the above embodiment, a circulating type inkjet head, which circulates and utilizes ink 9 between the ink tank 3 and the inkjet head 4, was described as an example, but it is not limited to this example. That is, for example, this disclosure may be applied to a non-circulating type inkjet head, in which ink 9 is not circulated between the ink tank 3 and the inkjet head 4. Also, in the above embodiment, the case in which the pressure loss in the recovery side common flow path Rout is greater than the pressure loss in the supply side common flow path Rin was described as an example, but it is not limited to this example. In other words, for example, the pressure loss on the supply side common channel Rin may be about the same as, or greater than, the pressure loss on the recovery side common channel Rout.

[0108] Furthermore, the above embodiment describes a configuration in which ink is ejected by deforming the actuator plate in a direction that expands the volume of the ejection channel by applying a voltage, and then restoring the actuator plate (so-called pull-and-shoot). However, the head chip is not limited to this configuration. The head chip according to this disclosure may also have a configuration in which ink is ejected by deforming the actuator plate in a direction that reduces the volume of the ejection channel by applying a voltage (so-called push-and-shoot). When push-and-shoot is performed, the actuator plate deforms so as to bulge outwards into the ejection channel when a drive voltage is applied. As a result, the volume inside the ejection channel decreases, the pressure inside the ejection channel increases, and the ink inside the ejection channel is ejected to the outside through the nozzle hole. When the drive voltage is reduced to zero, the actuator plate returns to its original state. As a result, the volume inside the ejection channel returns to its original state.

[0109] In addition, although the above embodiment describes a configuration in which the flow resistance of the first connecting passage 121 and the second connecting passage 122 is adjusted by adjusting the dimensions of the first connecting passage 121 and the second connecting passage 122 in the Z-axis direction, the configuration is not limited to this. The flow resistance of the first connecting passage 121 and the second connecting passage 122 may be adjusted, for example, by adjusting the dimensions of the first connecting passage 121 and the second connecting passage 122 in the X-axis direction or the Y-axis direction during the cover plate manufacturing process. Furthermore, although the above embodiment describes a case in which the first connecting passage 110 and the second connecting passage 111 each extend linearly in the Y-axis direction, the configuration is not limited to this. The first connecting passage 110 and the second connecting passage 111 each extend in a direction that intersects the Y-axis direction when viewed from the Z-axis direction. Also, the first connecting passage 110 and the second connecting passage 111 each may be formed in a curved shape or the like when viewed from the Z-axis direction. Furthermore, although the above embodiment describes a configuration in which the first communication passage 110 and the second communication passage 111 each penetrate the return plate 42 in the Z-axis direction over their entire length in the Y-axis direction, the configuration is not limited to this. As long as the first communication passage 110 and the second communication passage 111 each connect at least the discharge channel Ce, the nozzle hole Hn, and the first connecting passage 121 and the second connecting passage 122, it is sufficient if a portion of them penetrates in the Z-axis direction.

[0110] Furthermore, although the above embodiment describes a configuration in which the dimensions in the Z-axis direction of the first connecting passage 121 and the second connecting passage 122 are larger than the dimensions in the Y-axis direction of the first connecting passage 110 and the second connecting passage 111, the configuration is not limited to this. The dimensions in the Z-axis direction of the first connecting passage 121 may be less than or equal to the dimensions in the Y-axis direction of the first connecting passage 110 and the second connecting passage 111. Moreover, although the above embodiment describes a configuration in which the flow path cross-sectional area of ​​the first connecting passage 121 and the second connecting passage 122 gradually decreases from bottom to top, the configuration is not limited to this. The flow path cross-sectional area of ​​the first connecting passage 121 and the second connecting passage 122 may be configured to gradually increase from bottom to top, or it may be uniform over its entire length. In addition, although the above embodiment describes a configuration in which the dimensions in the X-axis direction of the communication downstream opening, which is the connection portion of the first connecting passage 110 to the first connecting passage 121, and the connection upstream opening, which is the connection portion of the first connecting passage 121 to the first connecting passage 110, are different, the configuration is not limited to this. The dimensions in the X-axis direction of the communication downstream opening, which is the connection portion of the first connecting passage 110 to the first connecting passage 121, and the connection upstream opening, which is the connection portion of the first connecting passage 121 to the first connecting passage 110, may be equal.

[0111] Furthermore, although the above embodiment describes a configuration in which the first chip module 41A and the second chip module 41B are superimposed, the configuration is not limited to this. For example, the head chip 40 may be composed of only the first chip module 41A. Moreover, although the above embodiment describes a configuration in which a plurality of first connecting passages 110 and a plurality of second connecting passages 111, and a plurality of first connecting paths 121 and a plurality of second connecting paths 122 are formed alternately in the X-axis direction, the configuration is not limited to this. The plurality of first connecting passages 110 and a plurality of second connecting passages 111, and a plurality of first connecting paths 121 and a plurality of second connecting paths 122 may be configured not to overlap when viewed from the X-axis direction (configuration spaced apart in the Y-axis direction). In this case, it is easier to adjust the dimensions of the plurality of first connecting passages 110 and a plurality of second connecting passages 111, and a plurality of first connecting paths 121 and a plurality of second connecting paths 122.

[0112] Furthermore, the printer method is not limited to the method described in the above embodiment; various other methods, such as the MEMS (Micro Electro Mechanical Systems) method, can be applied.

[0113] In addition, while the above embodiments have described specific examples of non-discharge driving methods using non-discharge pulses Pb, the methods are not limited to those listed in the above embodiments, and other methods may be used. Furthermore, for example, two or more of the methods listed in the embodiments may be used in appropriate combinations.

[0114] Furthermore, the series of processes described in the above embodiment may be performed by hardware (circuits) or by software (programs). If performed by software, the software consists of a group of programs that cause the computer to execute each function. Each program may, for example, be pre-installed in the computer or installed on the computer from a network or recording medium.

[0115] Furthermore, although the above embodiment described a printer 1 (inkjet printer) as a specific example of the "liquid jet recording device" in this disclosure, the invention is not limited to this example, and the disclosure can be applied to other devices other than inkjet printers. In other words, the "liquid jet head" (inkjet head) of this disclosure may be applied to other devices other than inkjet printers. Specifically, for example, the "liquid jet head" of this disclosure may be applied to devices such as facsimile machines, on-demand printers, 3D printing machines, adhesive application machines, and biomaterial formation machines that extrude biopolymers.

[0116] In addition, the various examples described so far may be applied in any combination.

[0117] Furthermore, the effects described herein are merely illustrative and not limiting, and other effects may also occur.

[0118] Furthermore, the present disclosure may also take the following configuration: (1) A liquid spray head comprising: an injection unit having a plurality of nozzles for spraying liquid; a plurality of pressure chambers individually communicating with the plurality of nozzles and each filled with the liquid; and a common flow path for the liquid extending along the direction of arrangement of the plurality of pressure chambers and communicating with each of the plurality of pressure chambers; and a drive unit that drives the injection unit based on a drive signal having one or more pulses within a predetermined printing cycle, thereby spraying the liquid filled in the pressure chambers from the nozzles, wherein the drive unit performs non-discharge driving to the non-discharge nozzles by including only non-discharge pulses in the drive signal, which have a pulse width in a range in which the liquid is not discharged from the non-discharge nozzles and are pulses that cause a minute vibration of the meniscus in the pressure chamber communicating with the non-discharge nozzles, at a discharge timing that includes both discharge nozzles from which the liquid is discharged and non-discharge nozzles from which the liquid is not discharged in the plurality of nozzles. (2) The liquid spray head according to (1) above, wherein the drive unit performs the non-discharge drive on the non-discharge nozzles at the discharge timing when the number of discharge nozzles is greater than the number of non-discharge nozzles. (3) The liquid spray head according to (1) or (2) above, wherein the drive unit performs the non-discharge drive on the non-discharge nozzles at the discharge timing when at least the nozzles adjacent to the non-discharge nozzles along the arrangement direction of the plurality of pressure chambers become discharge nozzles. (4) The liquid spray head according to any one of (1) to (3) above, wherein the drive unit performs the non-discharge drive on the non-discharge nozzles such that the phases of the pressure waves in the pressure chamber communicating with the discharge nozzles and the pressure chamber communicating with the non-discharge nozzles do not coincide. (5) The liquid spray head according to any one of (1) to (4) above, wherein the drive unit performs the non-discharge drive on the non-discharge nozzles such that a plurality of non-discharge pulses are included in the printing cycle.(6) The liquid injection head according to any one of (1) to (5), wherein the injection unit further comprises a liquid supply channel for supplying the liquid into the pressure chamber and a liquid recovery channel for recovering the liquid from the pressure chamber. (7) The liquid injection head according to (6), wherein the pressure loss on the liquid recovery channel side is greater than the pressure loss on the liquid supply channel side. (8) A liquid injection recording device equipped with the liquid injection head according to any one of (1) to (7).

[0119] This application claims priority based on Japanese Patent Application No. 2024-207550, filed with the Japan Patent Office on 28 November 2024, and all contents of that application are incorporated herein by reference.

[0120] Those skilled in the art will understand that various modifications, combinations, subcombinations, and changes can be conceived depending on design requirements and other factors, and that these fall within the scope of the attached claims and their equivalents.

Claims

1. A liquid spray head comprising: an injection unit having a plurality of nozzles for spraying liquid; a plurality of pressure chambers individually communicating with the plurality of nozzles and each filled with the liquid; and a common flow path for the liquid extending along the direction of arrangement of the plurality of pressure chambers and communicating with each of the plurality of pressure chambers; and a drive unit that drives the injection unit based on a drive signal having one or more pulses within a predetermined printing cycle, thereby spraying the liquid filled in the pressure chambers from the nozzles, wherein the drive unit performs non-discharge driving to the non-discharge nozzles by including only non-discharge pulses in the drive signal, which have a pulse width in a range in which the liquid is not discharged from the non-discharge nozzles and are pulses that cause minute vibrations of the meniscus in the pressure chamber communicating with the non-discharge nozzles, at a discharge timing that includes both discharge nozzles from which the liquid is discharged and non-discharge nozzles from which the liquid is not discharged in the plurality of nozzles.

2. The liquid spray head according to claim 1, wherein the drive unit performs the non-discharge drive on the non-discharge nozzles at the discharge timing when the number of discharge nozzles is greater than the number of non-discharge nozzles.

3. The liquid spray head according to claim 1, wherein the drive unit performs the non-discharge drive on the non-discharge nozzle when at least one of the nozzles adjacent to the non-discharge nozzle along the arrangement direction of the plurality of pressure chambers becomes a discharge nozzle at the discharge timing.

4. The liquid spray head according to any one of claims 1 to 3, wherein the drive unit performs the non-discharge drive on the non-discharge nozzle such that the phases of the pressure waves in the pressure chamber communicating with the discharge nozzle and the pressure chamber communicating with the non-discharge nozzle do not coincide.

5. The liquid spray head according to any one of claims 1 to 3, wherein the drive unit performs the non-ejection drive to the non-ejection nozzle such that a plurality of non-ejection pulses are included within the printing cycle.

6. The liquid injection head according to any one of claims 1 to 3, further comprising: a liquid supply channel for supplying the liquid into the pressure chamber; and a liquid recovery channel for recovering the liquid from the pressure chamber.

7. The liquid injection head according to claim 6, wherein the pressure loss on the liquid recovery channel side is greater than the pressure loss on the liquid supply channel side.

8. A liquid injection recording device comprising a liquid injection head according to any one of claims 1 to 3.

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