Liquid ejection head, liquid ejection recording device, and method for adjusting flow rate of liquid

Abstract

A liquid ejection head according to one embodiment of the present disclosure comprises: an ejection unit including a plurality of nozzles for ejecting a liquid, a plurality of pressure chambers individually communicating with the plurality of nozzles and each filled with the liquid, a liquid supply flow path for supplying the liquid into the pressure chambers, and a liquid recovery flow path for recovering the liquid from within the pressure chambers; and a drive unit that drives the ejection unit on the basis of a drive signal having one or a plurality of pulses within a predetermined printing cycle, to eject the liquid filled in the pressure chambers from the nozzles. When a predetermined liquid which is a thixotropic or pseudoplastic liquid is used, the drive unit performs micro-vibration drive on the predetermined liquid such that a micro-vibration pulse is included in the drive signal, the micro-vibration pulse having a pulse width within such a range that the predetermined liquid is not discharged from the nozzle and which causes micro-vibration of the predetermined liquid.

Description

Liquid ejection head, liquid ejection recording apparatus, and method for adjusting liquid flow rate

[0001] The present disclosure relates to a liquid ejection head, a liquid ejection recording apparatus, and a method for adjusting the flow rate of a liquid.

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

[0003] Japanese Patent Application Laid-Open No. 2006-62223

[0004] In such a liquid ejection head, generally, it is required to improve the ejection stability of the liquid. It is desirable to provide a liquid ejection head, a liquid ejection recording apparatus, and a method for adjusting the flow rate of a liquid that can improve the ejection stability of the liquid.

[0005] The liquid ejection head according to an embodiment of the present disclosure includes a plurality of nozzles that eject a liquid, a plurality of pressure chambers that communicate individually with the plurality of nozzles and are filled with the liquid respectively, a liquid supply channel that supplies the liquid into the pressure chambers, a liquid recovery channel that recovers the liquid from the pressure chambers, and an ejection unit having these. The driving unit drives the ejection unit based on a driving signal having one or a plurality of pulses within a predetermined printing cycle, thereby ejecting the liquid filled in the pressure chambers from the nozzles. When using a predetermined liquid that is a thixotropic or pseudoplastic liquid, the driving unit performs micro-vibration driving on the predetermined liquid by including, in the driving signal, a micro-vibration pulse having a pulse width within a range where the predetermined liquid is not ejected from the nozzle and being a pulse that micro-vibrates the predetermined liquid.

[0006] The 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] A liquid flow rate adjustment method according to one embodiment of the present disclosure involves driving a spray unit, which has a plurality of nozzles for spraying liquid, a plurality of pressure chambers that communicate individually with the plurality of nozzles and are each filled with liquid, a liquid supply channel for supplying liquid into the pressure chambers, a liquid recovery channel for recovering liquid from the pressure chambers, and a common liquid channel that extends along the direction of arrangement of the plurality of pressure chambers and communicates with each of the plurality of pressure chambers, based on a drive signal having one or more pulses within a predetermined printing cycle. When a predetermined liquid that is thixotropic or pseudoplastic is used to spray the liquid filled in the pressure chambers from the nozzles, the drive signal includes a micro-vibration pulse, which has a pulse width that does not cause the predetermined liquid to be discharged from the nozzles and is a pulse that causes the predetermined liquid to vibrate slightly, thereby performing micro-vibration driving on the predetermined liquid for some of the plurality of pressure chambers along the common channel.

[0008] According to one embodiment of the liquid injection head, liquid injection recording device, and liquid flow rate adjustment method of this disclosure, it is possible to improve the liquid discharge stability.

[0009] This is a schematic perspective view showing a schematic configuration example of a liquid injection recording device according to one embodiment of the present disclosure. This is a schematic diagram showing a schematic configuration example of the liquid injection head shown in Figure 1. This is an exploded perspective view showing a detailed configuration example of the liquid injection head shown in Figure 1. This is a schematic diagram showing a planar configuration example of an actuator plate, etc., shown in Figure 3. This is a schematic diagram showing a cross-sectional configuration example along the line V-V shown in Figure 4. This is a schematic diagram showing a cross-sectional configuration example along the line VI-VI shown in Figure 4. This is a schematic cross-sectional view showing an enlarged view of section VII shown in Figure 5. This is a schematic diagram showing an example of a supply path for each potential supplied from the drive unit to the drive electrode. This is a timing diagram schematically showing an example of a drive signal waveform. This is a timing diagram schematically showing various waveform examples in the drive signal. This is a characteristic diagram showing an example of the shear rate dependence of the viscosity of a liquid. This is a characteristic diagram showing an example of the time dependence of the viscosity of a liquid. This is a diagram showing an example of micro-vibration driving according to an embodiment. This is a timing diagram schematically showing an example of various pulses in the drive signal according to Comparative Examples 1 and 2 and Example 1. This is a diagram showing an example of various conditions according to Comparative Examples 1 and 2 and Example 1. This is a schematic timing diagram showing an example of various pulses in the drive signal according to Example 2. This is a schematic plan view illustrating an example of a micro-vibration drive method according to Example 3-1. This is a schematic plan view illustrating an example of a micro-vibration drive method according to Example 3-2.

[0010] 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 liquid injection head having a common flow path) 2. Modified examples

[0011] <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.

[0012] 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 supply pipe 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 ink 9 between the ink tank 3 and the inkjet head 4 will be used as an example. Note that in the drawings used in this specification, the scale of each component 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 a grid roller 21, a pinch roller 22, and a drive mechanism (not shown). This drive mechanism rotates the grid roller 21 around its axis (rotates it 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] (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.

[0018] 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 2 to 7).

[0019] The ink supply pipe 50 is a pipe through which ink 9 is supplied from the ink tank 3 to the inkjet head 4. This ink supply pipe 50 is made of a flexible hose that has enough flexibility to follow the operation of the scanning mechanism 6, which will be described below.

[0020] (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.

[0021] 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.

[0022] 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.

[0023] [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 2 to 7.

[0024] Figure 2 schematically shows an example of the general configuration of the inkjet head 4. For convenience, the cover plate 43, which will be described later, is not shown in Figure 2. Figure 3 is an exploded perspective view showing a detailed example of the inkjet head 4 shown in Figure 1. Figure 4 schematically shows an example of the planar configuration (X-Y planar configuration) of the actuator plate 42 etc. shown in Figure 3. For convenience, the actuator plate 42 of the inkjet head 4 is selectively shown in Figure 4. Figure 5 schematically shows an example of the cross-sectional configuration (Z-X cross-sectional configuration) along the V-V line shown in Figure 4, and Figure 6 schematically shows an example of the cross-sectional configuration (Z-Y cross-sectional configuration) along the VI-VI line shown in Figure 4. Figure 7 is an enlarged schematic cross-sectional view (Z-X cross-sectional view) of section VII shown in Figure 5.

[0025] The inkjet head 4 of this embodiment is a so-called side-chute type inkjet head that ejects ink 9 from the central part in the extending direction (Y-axis direction) of a plurality of channels (channels C1, C2) described later. Furthermore, as shown in Figures 2 to 7, this inkjet head 4 has a nozzle plate 41, an actuator plate 42, a cover plate 43, and a drive unit 49.

[0026] The nozzle plate 41, actuator plate 42, and cover plate 43 correspond to one specific example of the "injection unit" in this disclosure.

[0027] These nozzle plates 41, actuator plates 42, and cover plates 43 are bonded together, for example, using an adhesive, and are stacked in this order along the Z-axis. A flow path plate (not shown) having a predetermined flow path may also be provided on the upper surface of the cover plate 43. In the following description, the side with the cover plate 43 will be referred to as "upper" and the side with the nozzle plate 41 as "lower."

[0028] (B-1. Nozzle Plate 41) The nozzle plate 41 is a plate made of a film material such as polyimide or a metal material, and has a plurality of nozzle holes Hn (H1, H2) for ejecting ink 9 (see Figures 2 to 7). These nozzle holes Hn are each formed in a straight line at a predetermined interval (along the X-axis direction in this example). In addition, as shown in Figures 3 and 4, the nozzle plate 41 is provided with two rows of nozzles (nozzle rows 411, 412) that extend along the X-axis direction. These nozzle rows 411, 412 are arranged at a predetermined interval along the Y-axis direction. Thus, this inkjet head 4 is a two-row type inkjet head.

[0029] The nozzle row 411 has a plurality of nozzle holes H1 that are arranged in a straight line at predetermined intervals along the X-axis. Each of these nozzle holes H1 penetrates the nozzle plate 41 along its thickness direction (Z-axis direction) and communicates with the discharge channel C1e in the actuator plate 42, which will be described later. Specifically, as shown in Figure 4, each nozzle hole H1 is formed to be located in the central part along the Y-axis direction on the discharge channel C1e. Furthermore, the formation pitch of the nozzle holes H1 along the X-axis direction is the same as the formation pitch along the X-axis direction on the discharge channel C1e (same pitch). Ink 9 supplied from within the discharge channel C1e is discharged (jet) from the nozzle holes H1 in the nozzle row 411, as will be described in detail later.

[0030] Similarly, the nozzle row 412 has a plurality of nozzle holes H2 that are formed in a straight line at predetermined intervals along the X-axis. Each of these nozzle holes H2 also penetrates the nozzle plate 41 along its thickness and communicates with the discharge channel C2e in the actuator plate 42, which will be described later. Specifically, as shown in Figure 4, each nozzle hole H2 is formed to be located in the central part along the Y-axis on the discharge channel C2e. Furthermore, the formation pitch of the nozzle holes H2 along the X-axis is the same as the formation pitch along the X-axis on the discharge channel C2e. Ink 9 supplied from within the discharge channel C2e is also discharged from these nozzle holes H2 in the nozzle row 412, as will be described in detail later.

[0031] These nozzle holes Hn (H1, H2) are tapered through holes that gradually decrease in diameter as they extend downwards (see Figures 2, 5 to 7), and correspond to one specific example of a "nozzle" in this disclosure.

[0032] (B-2. Actuator Plate 42) The actuator plate 42 is a plate made of a piezoelectric material such as PZT (lead zirconate titanate), and although details will be described later, it is designed to change the volume in the discharge channels C1e and C2e, which will be described later. This actuator plate 42 is made of a single piezoelectric substrate whose polarization direction is set in one direction along the thickness direction (Z-axis direction) (a so-called cantilever type). However, the configuration of the actuator plate 42 is not limited to this cantilever type. That is, for example, the actuator plate 42 may be made by stacking two piezoelectric substrates with different polarization directions along the thickness direction (Z-axis direction) (a so-called chevron type).

[0033] Furthermore, as shown in Figures 3 and 4, the actuator plate 42 is provided with two rows of channel columns (channel columns 421 and 422) that extend along the X-axis direction. These channel columns 421 and 422 are arranged at a predetermined distance from each other along the Y-axis direction.

[0034] In such an actuator plate 42, as shown in Figure 4, the central part along the X-axis (the area where channel rows 421 and 422 are formed) is the ink ejection area (injection area) for the ink 9. On the other hand, both ends of the actuator plate 42 along the X-axis (the areas where channel rows 421 and 422 are not formed) are non-ejection areas (non-injection areas) for the ink 9. These non-ejection areas are located outside the ejection area along the X-axis. The ends of the actuator plate 42 along the Y-axis each constitute a tail portion 420 (see Figure 4).

[0035] As shown in Figures 3 and 4, the channel row 421 described above has a plurality of channels C1 extending along the Y-axis. These channels C1 are arranged in a line parallel to each other at predetermined intervals along the X-axis. As shown in Figures 3, 5, and 7, each channel C1 is defined by a drive wall Wd made of a piezoelectric material (actuator plate 42), and in cross-sectional view, it has a concave groove.

[0036] Similarly, channel row 422 has a plurality of channels C2 extending along the Y-axis direction, as shown in Figures 3 and 4. These channels C2 are arranged parallel to each other at predetermined intervals along the X-axis direction. Each channel C2 is also defined by the aforementioned drive wall Wd, as shown in Figure 3, and forms a concave groove in cross-section. Each drive wall Wd functions as an element (piezoelectric element) for individually pressurizing each channel C1, C2 (each discharge channel C1e, C2e, described later), as will be explained in detail later.

[0037] As shown in Figures 3 to 5, channel C1 contains an ejection channel C1e for ejecting ink 9 (filled with ink 9) and a dummy channel C1d that does not eject ink 9 (not filled with ink 9). In the channel row 421, these ejection channels C1e and dummy channels C1d are arranged alternately along the X-axis direction via the drive wall Wd described above. Each of the multiple ejection channels C1e communicates individually with a plurality of nozzle holes H1 in the nozzle plate 41, while each of the multiple dummy channels C1d does not communicate with these nozzle holes H1 and is covered from below by the upper surface of the nozzle plate 41 (see Figure 5).

[0038] Similarly, as shown in Figures 3 and 4, channel C2 contains an ejection channel C2e for ejecting ink 9 (filled with ink 9) and a dummy channel C2d that does not eject ink 9 (not filled with ink 9). In the channel row 422, these ejection channels C2e and dummy channels C2d are arranged alternately along the X-axis direction via the drive wall Wd described above. Each of the multiple ejection channels C2e is individually connected to a plurality of nozzle holes H2 in the nozzle plate 41, while each of the multiple dummy channels C2d is not connected to these nozzle holes H2 and is covered from below by the upper surface of the nozzle plate 41.

[0039] These discharge channels C1e and C2e correspond to specific examples of "pressure chambers" in this disclosure.

[0040] As shown in Figures 3 and 4, the ejection channel C1e and dummy channel C1d in channel C1 are arranged in an alternating pattern with respect to the ejection channel C2e and dummy channel C2d in channel C2. Therefore, in the inkjet head 4, the ejection channel C1e in channel C1 and the ejection channel C2e in channel C2 are arranged in a staggered pattern. Furthermore, as shown in Figure 3, in the actuator plate 42, shallow grooves Dd are formed in the portions corresponding to the dummy channels C1d and C2d, communicating with the outer ends of the dummy channels C1d and C2d along the Y-axis direction.

[0041] Furthermore, as shown in Figures 3 and 6, each discharge channel C1e has an arc-shaped side surface in which the cross-sectional area of ​​each discharge channel C1e gradually decreases from the cover plate 43 side (upper) to the nozzle plate 41 side (lower). Similarly, as shown in Figure 3, each discharge channel C2e has an arc-shaped side surface in which the cross-sectional area of ​​each discharge channel C2e gradually decreases from the cover plate 43 side to the nozzle plate 41 side. These arc-shaped side surfaces of discharge channels C1e and C2e are formed, for example, by cutting with a dicing machine.

[0042] Here, as shown in Figures 3, 5, and 7, drive electrodes Ed extending along the Y-axis are provided on the opposing inner surfaces of the drive wall Wd described above. In other words, a pair of drive electrodes Ed are arranged facing each other, with each drive wall Wd in between. These drive electrodes Ed include a common electrode Edc provided on the inner surface facing the discharge channels C1e and C2e, and individual electrodes Eda (active electrodes) provided on the inner surface facing the dummy channels C1d and C2d. Note that, as shown in Figures 3, 5, and 7, these drive electrodes Ed (common electrode Edc and individual electrode Eda) are formed only up to an intermediate position in the depth direction (Z-axis direction) on the inner surface of the drive wall Wd.

[0043] Within the same ejection channel C1e (or ejection channel C2e), a pair of common electrodes Edc facing each other are electrically connected to each other at a common terminal (not shown). Also, within the same dummy channel C1d (or dummy channel C2d), a pair of individual electrodes Eda facing each other are electrically separated from each other. On the other hand, a pair of individual electrodes Eda facing each other through the ejection channel C1e (or ejection channel C2e) are electrically connected to each other at an individual terminal (not shown).

[0044] Here, in the aforementioned tail portion 420, as shown in FIG. 3, a flexible printed circuit board 493 for electrically connecting between the drive electrode Ed and the drive unit 49 is mounted. The wiring pattern (not shown) formed on this flexible printed circuit board 493 is electrically connected to the above-described common terminal and individual terminal. Thereby, a drive voltage Vd (drive signal Sd) or the like described later is applied to each drive electrode Ed from the drive unit 49 described later via the flexible printed circuit board 493 (see FIG. 2).

[0045] (B - 3. Cover plate 43) The cover plate 43 is arranged to block each channel C1, C2 (each channel row 421, 422) in the actuator plate 42, as shown in FIGS. 3, 5 to 7. Specifically, this cover plate 43 is adhered to the upper surface of the actuator plate 42 and has a plate-like structure.

[0046] As shown in FIGS. 3 and 6, a pair of supply-side common channels Rin1, Rin2 and a pair of recovery-side common channels Rout1, Rout2 are respectively formed in the cover plate 43. Also, as shown in FIG. 6, wall portions W1, W2 are formed in this cover plate 43.

[0047] The wall portion W1 is arranged to cover the upper sides of the ejection channel C1e and the dummy channel C1d, and the wall portion W2 is arranged to cover the upper sides of the ejection channel C2e and the dummy channel C2d (see FIG. 6).

[0048] The supply-side common flow paths Rin1 and Rin2 and the recovery-side common flow paths Rout1 and Rout2 each extend along the X-axis direction and are arranged parallel to each other at a predetermined interval along the Y-axis direction, as shown in Figure 3. The supply-side common flow path Rin1 and the recovery-side common flow path Rout1 are each formed in the region corresponding to the channel row 421 (multiple channels C1) in the actuator plate 42 (see Figures 3 and 6). On the other hand, the supply-side common flow path Rin2 and the recovery-side common flow path Rout2 are each formed in the region corresponding to the channel row 422 (multiple channels C2) in the actuator plate 42 (see Figures 3 and 6).

[0049] The supply-side common flow path Rin1 is formed near the inner end (one side of the wall W1) along the Y-axis direction in each channel C1, and is a concave groove (see Figures 3 and 6). In this supply-side common flow path Rin1, a supply slit Sin1 is formed in the region corresponding to each discharge channel C1e, penetrating the cover plate 43 along its thickness direction (Z-axis direction) (see Figures 3 and 6). Similarly, the supply-side common flow path Rin2 is formed near the inner end (one side of the wall W2) along the Y-axis direction in each channel C2, and is a concave groove (see Figures 3 and 6). In this supply-side common flow path Rin2, a supply slit Sin2 is also formed in the region corresponding to each discharge channel C2e, penetrating the cover plate 43 along its thickness direction (see Figure 3).

[0050] The recovery-side common channel Rout1 is formed near the outer end (the other side of the wall W1) along the Y-axis direction in each channel C1, and is a concave groove (see Figures 3 and 6). In this recovery-side common channel Rout1, a recovery slit Sout1 is formed in the region corresponding to each discharge channel C1e, penetrating the cover plate 43 along its thickness direction (see Figures 3 and 6). Similarly, the recovery-side common channel Rout2 is formed near the outer end (the other side of the wall W2) along the Y-axis direction in each channel C2, and is a concave groove (see Figures 3 and 6). In this recovery-side common channel Rout2, a recovery slit Sout2 is also formed in the region corresponding to each discharge channel C2e, penetrating the cover plate 43 along its thickness direction (see Figure 3).

[0051] Here, the supply-side common flow paths Rin1 and Rin2 each correspond to a specific example of the "liquid supply flow path" in this disclosure. On the other hand, the recovery-side common flow paths Rout1 and Rout2 each correspond to a specific example of the "liquid recovery flow path" in this disclosure. Furthermore, these supply-side common flow paths Rin1 and Rin2 and the recovery-side common flow paths Rout1 and Rout2 each correspond to a specific example of the "common flow path" in this disclosure.

[0052] In this manner, the supply-side common flow path Rin1 and the recovery-side common flow path Rout1 are connected to each discharge channel C1e via the supply slit Sin1 and the recovery slit Sout1, respectively (see Figures 3 and 6). The supply slit Sin1 and the recovery slit Sout1 are also through-holes through which ink 9 flows to and from the discharge channel C1e. Specifically, the supply-side common flow path Rin1 supplies ink 9 into the discharge channel C1e via the supply slit Sin1, while the recovery-side common flow path Rout1 recovers ink 9 from within the discharge channel C1e via the recovery slit Sout1 (see the dashed arrow in Figure 6). On the other hand, neither the supply-side common flow path Rin1 nor the recovery-side common flow path Rout1 are connected to each dummy channel C1d. Specifically, each dummy channel C1d is blocked by the bottom of the supply-side common flow path Rin1 and the recovery-side common flow path Rout1.

[0053] Similarly, the supply-side common channel Rin2 and the recovery-side common channel Rout2 are connected to each discharge channel C2e via the supply slit Sin2 and the recovery slit Sout2, respectively (see Figure 3). The supply slit Sin2 and the recovery slit Sout2 are also through-holes through which ink 9 flows to and from the discharge channel C2e. Specifically, the supply-side common channel Rin2 supplies ink 9 into the discharge channel C2e via the supply slit Sin2, while the recovery-side common channel Rout2 recovers ink 9 from within the discharge channel C2e via the recovery slit Sout2. On the other hand, neither the supply-side common channel Rin2 nor the recovery-side common channel Rout2 are connected to each dummy channel C2d (see Figure 6). Specifically, each dummy channel C2d is blocked by the bottom of these supply-side common channel Rin2 and recovery-side common channel Rout2 (see Figure 6).

[0054] (B-4. 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).

[0055] Furthermore, the drive unit 49 drives the actuator plate 42 to perform ejection so that the ink 9 filled in the aforementioned ejection channels C1e and C2e is ejected from the nozzle holes Hn (H1, H2) (see Figures 2, 5 to 7). Specifically, the drive unit 49 applies the above-mentioned drive voltage Vd (drive signal Sd) to the actuator plate 42, causing the ejection channels C1e and C2e to expand and contract, thereby ejecting the ink 9 from each nozzle hole Hn (performing an ejection operation).

[0056] [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.

[0057] Figure 8 schematically illustrates an example of the supply path for each potential supplied from the drive unit 49 to the drive electrode Ed (individual electrode Eda and common electrode Edc). Specifically, Figure 8 shows examples of the supply paths for channel C1 for the potential supplied to the individual electrode Eda (individual potential Vda) and the potential supplied to the common electrode Edc (common potential Vdc).

[0058] For convenience, the same applies to the example supply path for channel C2 (example supply path for individual potential Vda and common potential Vdc), although it is omitted from Figure 8.

[0059] 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.

[0060] 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 channels C1e and C2e 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).

[0061] 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 (potential difference between individual potential Vda and common potential Vdc) is set to a negative value (Vd < 0), but this example is not limited to this. That is, for example, the common potential Vdc may be set to 0 (ground potential) and the individual potential Vda may 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 of drive, it is possible to perform the same drive (pressure fluctuation at the actuator plate 42) as in the drive 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 may be set to only a positive or negative value.

[0062] 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 channels C1e and C2e (expansion pulse), and pulse p2 is a pulse for contracting the volume of the ejection channels C1e and C2e (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.

[0063] 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).

[0064] 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 micro-vibration pulses Pb that have a pulse width (pulse widths Wb1 and Wb2 described later) that corresponds to the range (degree) in which ink 9 is not ejected from the nozzle hole Hn, and that cause the ink 9 (the predetermined ink 90 described later) itself to vibrate slightly.

[0065] Incidentally, the pulse widths Wb1 and Wb2 in the range where ink 9 is not ejected from the nozzle hole Hn are, for example, about 1 / 6 to 1 / 3 of the resonant period (AP: Acoustic Period). In other words, the range of pulse widths Wb1 and Wb2 is, for example, (AP / 6) ≤ (Wb1, Wb2) ≤ (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 larger than the pulse widths Wb1 and Wb2 described above. In other words, the range of pulse width Wj is, for example, (AP / 3) < Wj.

[0066] The AP mentioned above corresponds to a period of half the natural vibration period of the ink 9 within the ejection channels C1e and C2e (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 channels C1e and C2e and the physical properties of the ink 9 (specific gravity, etc.).

[0067] Details of these discharge pulses Pj and micro-vibration pulses Pb will be described later (Figures 13 to 18).

[0068] [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 ink supply pipe 50.

[0069] In this initial state, when the printer 1 is activated, the grid rollers 21 in the transport mechanisms 2a and 2b rotate, causing the recording paper P to be transported between the grid rollers 21 and the pinch roller 22 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, to operate 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) eject four colors of ink 9 onto the recording paper P as appropriate, thereby recording images, characters, etc., onto the recording paper P.

[0070] (B. Detailed operation of inkjet head 4) Next, we will explain the detailed operation of inkjet head 4.

[0071] First, the inkjet head 4 performs the ink ejection operation using the shear mode as follows. In other words, the drive unit 49 performs ejection drive on the actuator plate 42 using the aforementioned drive signal Sd, causing the ink 9 filled in the ejection channels C1e and C2e to be ejected from the nozzle holes Hn.

[0072] During such discharge driving, the drive unit 49 applies a drive voltage Vd (drive signal Sd) to the drive electrodes Ed (common electrode Edc and individual electrode Eda) in the actuator plate 42. Specifically, the drive unit 49 applies a drive voltage Vd to each drive electrode Ed (common electrode Edc and individual electrode Eda) located on a pair of drive walls Wd that define the discharge channels C1e and C2e. As a result, these pairs of drive walls Wd deform so that they protrude toward the dummy channels C1d and C2d adjacent to their respective discharge channels C1e and C2e.

[0073] As mentioned above, in the actuator plate 42, the polarization direction is set to one direction, and the drive electrode Ed is formed only up to an intermediate position in the depth direction on the inner surface of the drive wall Wd. Therefore, when the drive voltage Vd is applied by the drive unit 49, the drive wall Wd bends and deforms in a V-shape around the intermediate position in the depth direction of the drive wall Wd. As a result of this bending deformation of the drive wall Wd, the discharge channels C1e and C2e deform as if they are expanding (see the expansion direction d11 shown in Figure 7).

[0074] Incidentally, if the actuator plate 42 is of the chevron type described above, rather than the cantilever type, the drive wall Wd will bend and deform in a V-shape as follows. That is, in the case of this chevron type, the polarization direction of the actuator plate 42 is different along the thickness direction (the two piezoelectric substrates described above are stacked), and the drive electrode Ed is formed over the entire depth direction on the inner surface of the drive wall Wd. Therefore, when the drive voltage Vd is applied by the drive unit 49 described above, the drive wall Wd will bend and deform in a V-shape, centered on the intermediate position in the depth direction of the drive wall Wd. As a result, even in this case, the discharge channels C1e and C2e will deform as if they were expanding due to this bending deformation of the drive wall Wd (see the expansion direction d11 shown in Figure 7).

[0075] In this way, the volume of the discharge channels C1e and C2e increases due to the bending deformation caused by the piezoelectric thickness sliding effect at the pair of drive walls Wd. As a result of the increased volume of the discharge channels C1e and C2e, the ink 9 stored in the supply-side common flow paths Rin1 and Rin2 is guided into the discharge channels C1e and C2e via the supply slits Sin1 and Sin2 (see, for example, the dashed arrows in Figure 6).

[0076] Next, the ink 9, which has been guided into the ejection channels C1e and C2e in this manner, propagates as a pressure wave inside the ejection channels C1e and C2e. At the moment when this pressure wave reaches (or near the moment) the nozzle hole Hn of the nozzle plate 41, the drive voltage Vd applied to the drive electrode Ed becomes 0 V. As a result, the drive wall Wd recovers from the bent deformation state described above, and the volume of the ejection channels C1e and C2e, which had increased, returns to its original size (see, for example, the contraction direction db shown in Figure 7).

[0077] In this way, as the volumes of the ejection channels C1e and C2e return to their original state, the pressure inside the ejection channels C1e and C2e increases, and the ink 9 inside the ejection channels C1e and C2e is pressurized. As a result, droplet-shaped ink 9 is ejected to the outside (towards the recording paper P, etc.) through the nozzle hole Hn (see Figures 2, 5 to 7). In this way, the ink jetting operation (ejection operation) of the ink 9 in the inkjet head 4 is performed, and as a result, the recording operation (printing operation) of images, characters, etc. is performed on the recording paper P.

[0078] Furthermore, a portion of the ink 9 filling the ejection channels C1e and C2e is recovered into the common recovery channels Rout1 and Rout2 via the recovery slits Sout1 and Sout2 (see, for example, the dashed arrows in Figure 6). The ink 9 recovered into these common recovery channels Rout1 and Rout2 is then returned to the ink tank 3 from within the inkjet head 4 via the ink supply pipe 50. In this way, the ink 9 is circulated.

[0079] (C. Micro-vibration drive using micro-vibration pulse Pb) Next, the micro-vibration drive using the aforementioned micro-vibration pulse Pb in this embodiment (micro-vibration drive that causes the predetermined ink 90, described later, to vibrate minutely) will be explained in detail.

[0080] (C-1. Challenges in Inkjet Heads) First, in conventional inkjet heads, when using high-viscosity inks, the upper limit of viscosity for stable ink ejection is generally around 20 mPa·s. When using inks with higher viscosity than that, a mechanism is needed to heat the ink tank or the inkjet head itself to reduce the viscosity of the ink. As a result, conventional methods have led to challenges such as increased complexity of the configuration, higher equipment costs, and increased power consumption, making it difficult to improve the stability of ink ejection. Furthermore, there is a preconceived notion that liquids with a static viscosity exceeding, for example, 1000 mPa·s, cannot be ejected at all, and currently, such applications are not being implemented.

[0081] Here, Figure 11 shows an example of the shear rate dependence of a liquid viscosity as a characteristic diagram. Specifically, Figure 11 shows an example of the relationship between viscosity and shear rate for both water-based metallic base coatings and solvent-based metallic base coatings, which are thixotropic or pseudoplastic liquids. Figure 12 shows an example of the time dependence of a liquid viscosity as a characteristic diagram. The characteristic data shown in Figures 11 and 12 are quoted from non-patent literature (Kazuyuki Tate: Journal of the Color Materials Association, Rheology and Appearance Quality of Automotive Topcoats, 76[8], 307-312 (2003)).

[0082] In the example of the water-based metallic paint shown in Figure 12, when the shear rate is relatively low, it exhibits a very high viscosity of about 20,000 to 30,000 (mPa·s). On the other hand, when the shear rate is relatively high (for example, 10 ４ (s －１ In cases such as ( ), the viscosity can be reduced to about 30-50 (mPa·s). In other words, as will be described later, it is possible to reduce the viscosity of a liquid (reduce viscosity) by causing it to vibrate slightly and increasing its shear rate. Furthermore, as shown in Figure 13, for example, the viscosity of a liquid is time-dependent, and it can be seen that the viscosity recovery operation occurs on the order of time, which is longer than the time interval of a typical drive frequency (around a few kHz) in an inkjet head.

[0083] Therefore, even when dispensing the thixotropic or pseudoplastic ink 9 (predetermined ink 90) described above, it is desirable to propose a method that can reduce the viscosity of the predetermined ink 90 and improve dispensing stability. This predetermined ink 90 corresponds to one specific example of the "predetermined liquid" in this disclosure.

[0084] (C-2. Driving Method of This Embodiment) In this embodiment, when using a predetermined ink 90 having the thixotropic or pseudoplastic properties described above, micro-vibration driving is performed using the micro-vibration pulse Pb described above. Specifically, this micro-vibration pulse Pb (a pulse having pulse widths Wb1, Wb2 in a range in which the predetermined ink 90 is not ejected from the nozzle hole Hn, and a pulse that causes the predetermined ink 90 to vibrate slightly) is included in the driving signal Sd, and micro-vibration driving is performed on the predetermined ink 90. ​​This makes it possible to effectively bring out the viscosity-shear rate dependence of the predetermined ink 90 (see Figure 11 described above), and the viscosity of the predetermined ink 90 is reduced.

[0085] Here, Figure 13 shows an example of micro-vibration driving according to this embodiment (micro-vibration driving using the micro-vibration pulse Pb described above). Figure 14 schematically shows examples of various pulses in the drive signal Sd for Comparative Examples 1 and 2 (when the drive signal Sd does not contain the micro-vibration pulse Pb) and Example 1 of this embodiment (when the drive signal Sd contains the micro-vibration pulse Pb) as timing diagrams. Specifically, Figures 14(A) to (C) show the drive signals Sd for Comparative Example 1, Example 1, and Comparative Example 2, respectively. Figure 15 is a table showing examples of various conditions for Comparative Examples 1 and 2 and Example 1. Figure 16 schematically shows examples of various pulses in the drive signal Sd for Example 2 of this embodiment as timing diagrams. Figures 17 and 18 are schematic plan views for explaining examples of micro-vibration driving methods according to Examples 3-1 and 3-2 of this embodiment, respectively. In both Figures 14 and 16, the vertical axis represents the voltage value of the drive voltage Vd, and the horizontal axis represents time t. Also, in the example of the discharge pulse Pj shown in Figures 14(A) to (C), for convenience, multiple pulses (the aforementioned pulses p1 and p2) are shown together.

[0086] First, as shown in Figure 13, in this embodiment, when using the predetermined ink 90 having the thixotropic or pseudoplastic properties described above, the aforementioned micro-vibration pulse Pb is included in the drive signal Sd, and micro-vibration driving is performed on the predetermined ink 90, as will be described in detail below.

[0087] Furthermore, as shown in Figure 13, the drive unit 49 performs micro-vibration driving as follows when, for example, a plurality of nozzle holes Hn include both ejection nozzles Hnj from which the predetermined ink 90 is ejected and non-ejection nozzles Hnn from which the predetermined ink 90 is not ejected. That is, the drive unit 49 performs micro-vibration driving on the predetermined ink 90, for example, targeting the non-ejection nozzles Hnn among these ejection nozzles Hnj and non-ejection nozzles Hnn. Alternatively, the drive unit 49 performs micro-vibration driving on the predetermined ink 90, for example, targeting both ejection nozzles Hnj and non-ejection nozzles Hnn.

[0088] In Comparative Example 1 shown in Figure 14(A), only the ejection pulse Pj that defines the printing cycle Tp (= ejection cycle Tj, drive cycle Td) is provided continuously along the time axis. Similarly, in Comparative Example 2 shown in Figure 14(C), only the ejection pulse Pj that defines the printing cycle Tp (= ejection cycle Tj, drive cycle Td) is provided continuously along the time axis. However, the printing cycle Tp in Comparative Example 1 (for example, 12 [kHz]) is several times (6 times in this example) the printing cycle Tp in Comparative Example 2 (for example, 2 [kHz]).

[0089] On the other hand, in Embodiment 1 shown in Figure 14(B), one or more micro-vibration pulses Pb1 (in this example, five micro-vibration pulses Pb1) are provided between ejection pulses Pj that define the printing cycle Tp (= ejection cycle Tj, ≠ drive cycle Td). Incidentally, in Embodiment 1, multiple drive cycles Td are provided within the printing cycle Tp, defined by the ejection pulses Pj and the micro-vibration pulses Pb1. Furthermore, in Embodiment 2 shown in Figure 16, one or more micro-vibration pulses Pb2 (in this example, multiple micro-vibration pulses Pb2) are further provided within at least one of the multiple drive cycles Td in the drive signal Sd. In Embodiment 2, the addition of such micro-vibration pulses Pb2 makes it easier to fine-tune the viscosity when achieving the aforementioned low viscosity in the predetermined ink 90. Furthermore, the pulse widths Wb1 and Wb2 of these micro-vibration pulses Pb1 and Pb2 are, as mentioned above, for example, (AP / 6) ≤ Wb1 ≤ (AP / 3) and (AP / 6) ≤ Wb2 ≤ (AP / 3).

[0090] Here, for example, as shown in Figure 13, the drive unit 49 may perform the above-described micro-vibration drive so that the viscosity Vi of the predetermined ink 90 approaches a predetermined target viscosity Vit, as follows: That is, the drive unit 49 may adjust, for example, the number of pulses Nb of the micro-vibration pulses Pb (=Pb1, Pb2) included in the printing cycle Tp.

[0091] Furthermore, in the example of various conditions shown in Figure 15, in Comparative Example 2, the high-viscosity predetermined ink 90 cannot be ejected due to the low ejection frequency fj. On the other hand, in Example 1, by providing a micro-vibration pulse Pb in the drive signal Sd, even if the ejection frequency fj changes from that of Comparative Example 1, the aforementioned shear rate can be kept at the same level as in Comparative Example 1, and an average ejection speed equivalent to that of Comparative Example 1 can be achieved.

[0092] Furthermore, as shown in embodiments 3-1 and 3-2 in Figures 17 and 18, for example, micro-vibration driving for a predetermined ink 90 may be performed with respect to a plurality of channels C2 along a common flow path (supply-side common flow path Rin2 and recovery-side common flow path Rout2) as described below. Note that in Figures 17 and 18, for convenience, a plurality of channels C2 along the supply-side common flow path Rin2 and the recovery-side common flow path Rout2 are shown, but the same applies to a plurality of channels C1 along the supply-side common flow path Rin1 and the recovery-side common flow path Rout1, which are also common flow paths.

[0093] First, in the embodiment 3-1 shown in Figure 17, all of the multiple channels C2 along the common flow path described above are set as channels C2a that are targeted for micro-vibration driving, and then micro-vibration driving is performed on the predetermined ink 90. ​​In this case, the shear rate of the predetermined ink 90 is made uniform in all channels C2 (=C2a) along the common flow path, and the viscosity of the predetermined ink 90 is also made uniform.

[0094] On the other hand, in the embodiment 3-2 shown in Figure 18, some of the multiple channels C2 along the common flow path described above are set as channels C2a that are subject to micro-vibration driving, and then micro-vibration driving is performed on the predetermined ink 90. ​​Therefore, of the multiple channels C2 along the common flow path, the remaining channels C2 other than the channel C2a described above are set as channels C2n that are not subject to micro-vibration driving. In this case, the shear rate of the predetermined ink 90 can be made different between the multiple channels C2 along the common flow path (between channels C2a and C2n described above), and the viscosity of the predetermined ink 90 can also be made different. Therefore, the ease of flow of the predetermined ink 90 can be controlled (made variable) between the multiple channels C along the common flow path, making it possible to perform a pseudo-variable valve-like operation. In other words, even in this case, the ease of flow of the predetermined ink 90 can be arbitrarily adjusted, making it possible to improve the discharge stability of the predetermined ink 90. In the examples shown in Figures 17 and 18, the method is applied to multiple channels C2 along a common flow path. However, it may also be applied to any multiple channels C2 (and any multiple channels C1) within the inkjet head 4.

[0095] Furthermore, as shown in Figure 13, for example, the drive unit 49 may perform micro-vibration driving on the predetermined ink 90 when filling the inkjet head 4 with the predetermined ink 90, as described above. This is because when using a high-viscosity predetermined ink 90 as described above, it may be difficult to fill the ink 90 into the very narrow space inside the inkjet head 4. In particular, residual air bubbles inside the inkjet head 4 can lead to failure to eject the predetermined ink 90, so such a situation must be avoided. Therefore, it is desirable to reduce the viscosity of the predetermined ink 90 even during filling by performing micro-vibration driving on the predetermined ink 90.

[0096] (D. Function and Effects) In this embodiment, when using thixotropic or pseudoplastic ink 9 (predetermined ink 90), the above-mentioned micro-vibration pulse Pb is included in the drive signal Sd, thereby performing micro-vibration driving on the predetermined ink 90. ​​By causing the predetermined ink 90 to vibrate micro-vibration in this manner, the viscosity of the predetermined ink 90 is reduced as described above. Therefore, stable ejection of the predetermined ink 90 becomes easier in the inkjet head 4 of the circulating type (structure including supply-side common flow paths Rin1, Rin2 and recovery-side common flow paths Rout1, Rout2) described above. As a result, in this embodiment, it is possible to improve the ejection stability of the ink 9 (predetermined ink 90).

[0097] Furthermore, in this embodiment, if micro-vibration driving is performed on a portion of the multiple channels C1 and C2 along the common flow path described above for the predetermined ink 90, the following occurs. That is, it becomes possible to stabilize the circulation flow rate of the predetermined ink 90 within the inkjet head 4, and it also becomes possible to control the circulation flow rate of the predetermined ink 90.

[0098] Furthermore, in this embodiment, if the number of pulses of the micro-vibration pulses Pb included in the printing cycle Tp is adjusted during the micro-vibration drive described above so that the viscosity Vi of the predetermined ink 90 approaches a predetermined target viscosity Vit, the following occurs. That is, it becomes possible to stabilize the circulation flow rate of the predetermined ink 90 within the inkjet head 4, and it also becomes possible to control the circulation flow rate of the predetermined ink 90.

[0099] In addition, in this embodiment, if the above-described micro-vibration drive is performed when filling the inkjet head 4 with the predetermined ink 90, the following occurs. That is, even when filling the predetermined ink 90 in this manner, by performing a micro-vibration drive on the predetermined ink 90, it is possible to reduce the viscosity of the predetermined ink 90 even during filling, and to improve the filling performance of the predetermined ink 90.

[0100] <2. Modifications> The present disclosure has been described above with reference to embodiments and examples, but the present disclosure is not limited to these embodiments, and various modifications are possible.

[0101] For example, in the above embodiments, 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 embodiments, and other shapes, arrangements, numbers, etc., may be used. Also, the values, ranges, and magnitude relationships of the various parameters described in the above embodiments are not limited to those described in the above embodiments, and other values, ranges, and magnitude relationships may be used.

[0102] Specifically, in the above embodiments, 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 invention is not limited to those described in the above embodiments.

[0103] Furthermore, various types of inkjet head structures can be applied. That is, in the above embodiment, for example, a so-called side-chute type inkjet head, which ejects ink 9 from the center of the extending direction of each ejection channel in the actuator plate, was used as an example. However, it is not limited to this example, and for example, an edge-chute type inkjet head, which ejects ink 9 along the extending direction of each ejection channel, may also be used.

[0104] Furthermore, the printer method is not limited to the methods described in the above embodiments, etc., and various other methods can be applied, such as the MEMS (Micro Electro Mechanical Systems) method.

[0105] In addition, while the above embodiments have described specific examples of methods for driving micro-vibrations using micro-vibration 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.

[0106] Furthermore, the series of processes described in the above embodiments 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.

[0107] Furthermore, while the above embodiments 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 besides inkjet printers. In other words, the "liquid jet head" (inkjet head) of this disclosure may be applied to other devices besides 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.

[0108] In addition, the various examples described so far may be applied in any combination.

[0109] Furthermore, the effects described herein are merely illustrative and not limiting, and other effects may also occur.

[0110] Furthermore, the present disclosure may also take the following configuration: (1) A spray unit having a plurality of nozzles for spraying liquid, a plurality of pressure chambers communicating individually with the plurality of nozzles and each filled with the liquid, a liquid supply channel for supplying the liquid into the pressure chambers, and a liquid recovery channel for recovering the liquid from the pressure chambers; and a drive unit that drives the spray 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, when using a predetermined liquid which is thixotropic or pseudoplastic, has a pulse width in a range in which the predetermined liquid is not discharged from the nozzles, and the drive signal includes a micro-vibration pulse which is the pulse that causes the predetermined liquid to vibrate slightly, thereby performing micro-vibration drive on the predetermined liquid. (2) The liquid spray head according to (1) above, wherein the drive unit performs the micro-vibration drive on the non-discharge nozzles among the plurality of nozzles at a discharge timing that includes both a discharge nozzle from which the predetermined liquid is discharged and a non-discharge nozzle from which the predetermined liquid is not discharged. (3) The liquid spray head according to (1) above, wherein the drive unit performs the micro-vibration drive on both the discharge nozzles and the non-discharge nozzles among the plurality of nozzles at a discharge timing that includes both a discharge nozzle from which the predetermined liquid is discharged and a non-discharge nozzle from which the predetermined liquid is not discharged. (4) The liquid spray head according to any one of (1) to (3) above, wherein the drive unit adjusts the number of micro-vibration pulses included in the printing cycle during the micro-vibration drive so that the viscosity of the predetermined liquid approaches a predetermined target viscosity. (5) The liquid spray head according to any one of (1) to (4) above, wherein the drive unit performs the micro-vibration drive when filling the liquid spray head with the predetermined liquid. (6) The liquid injection head according to any one of (1) to (5) above, wherein the injection section further has a common flow path for the liquid that extends along the direction of arrangement of the plurality of pressure chambers and communicates with each of the plurality of pressure chambers.(7) A liquid spray recording device equipped with a liquid spray head as described in any of (1) to (6) above. (8) A method for adjusting the flow rate of a liquid spray unit, which has a plurality of nozzles for spraying liquid, a plurality of pressure chambers that communicate individually with the plurality of nozzles and are each filled with the liquid, a liquid supply channel for supplying the liquid into the pressure chambers, a liquid recovery channel for recovering the liquid from the pressure chambers, and a common channel for the liquid that extends along the direction in which the plurality of pressure chambers are arranged and communicates with each of the plurality of pressure chambers, and which sprays the liquid filled in the pressure chambers from the nozzles by driving the spray unit based on a drive signal having one or more pulses within a predetermined printing cycle, wherein when a predetermined liquid that is thixotropic or pseudoplastic is used, the drive signal includes a micro-vibration pulse which has a pulse width in a range in which the predetermined liquid is not discharged from the nozzle and is a pulse that causes the predetermined liquid to vibrate slightly, and the micro-vibration drive for the predetermined liquid is performed on a portion of the pressure chambers of the plurality of pressure chambers along the common channel.

[0111] This application claims priority based on Japanese Patent Application No. 2024-207552, filed with the Japan Patent Office on 28 November 2024, and all contents of that application are incorporated herein by reference.

[0112] 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: a spray 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; a liquid supply channel for supplying the liquid into the pressure chambers; and a liquid recovery channel for recovering the liquid from the pressure chambers; and a drive unit that drives the spray 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, when using a predetermined liquid which is thixotropic or pseudoplastic, the drive unit includes a micro-vibration pulse in the drive signal that has a pulse width within a range in which the predetermined liquid is not discharged from the nozzles, and that causes the predetermined liquid to vibrate minutely, thereby performing micro-vibration driving on the predetermined liquid.

2. The liquid spray head according to claim 1, wherein the drive unit performs the micro-vibration drive on the non-discharge nozzles among the plurality of nozzles at a discharge timing that includes both a discharge nozzle from which the predetermined liquid is discharged and a non-discharge nozzle from which the predetermined liquid is not discharged.

3. The liquid spray head according to claim 1, wherein the drive unit performs the micro-vibration drive on both the discharge nozzles and the non-discharge nozzles at a discharge timing that includes both a discharge nozzle from which the predetermined liquid is discharged and a non-discharge nozzle from which the predetermined liquid is not discharged.

4. The liquid spray head according to any one of claims 1 to 3, wherein the drive unit adjusts the number of pulses of the micro-vibration pulses included in the printing cycle during the micro-vibration drive so that the viscosity of the predetermined liquid approaches a predetermined target viscosity.

5. The liquid spray head according to any one of claims 1 to 3, wherein the drive unit performs the micro-vibration drive when filling the liquid spray head with the predetermined liquid.

6. The liquid injection head according to any one of claims 1 to 3, wherein the injection section further has a common flow path for the liquid that extends along the direction of arrangement of the plurality of pressure chambers and communicates with each of the plurality of pressure chambers.

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

8. A method for adjusting the flow rate of a liquid, wherein when a predetermined liquid is used, which is a liquid having thixotropy or pseudoplastic properties, the method involves driving a spray unit, which has a plurality of nozzles for spraying liquid, a plurality of pressure chambers that communicate individually with the plurality of nozzles and are each filled with the liquid, a liquid supply channel for supplying the liquid into the pressure chambers, a liquid recovery channel for recovering the liquid from the pressure chambers, and a common channel for the liquid that extends along the direction in which the plurality of pressure chambers are arranged and communicates with each of the plurality of pressure chambers, based on a drive signal having one or more pulses within a predetermined printing cycle, to spray the liquid filled in the pressure chambers from the nozzles, the method involves including a micro-vibration pulse in the drive signal, which has a pulse width in a range in which the predetermined liquid is not discharged from the nozzles and is a pulse that causes the predetermined liquid to vibrate slightly, and performing micro-vibration driving on the predetermined liquid for some of the pressure chambers among the plurality of pressure chambers along the common channel.

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