Liquid jet head, liquid jet recording device and control method of liquid jet head

Abstract

To provide a liquid jet head and the others which can improve reliability on discharging.SOLUTION: A liquid jet head according to one embodiment described in the disclosure comprises: a jetting part which has a plurality of nozzles, a plurality of pressure chambers communicated with the plurality of nozzles respectively, which are respectively filled with liquid, a liquid supply chamber that supplies liquid into the pressure chambers, and a liquid recovery chamber that recovers liquid from the pressure chambers; and a driving part that drives the jetting part on the basis of a driving signal to make the nozzles jet liquid filled into the pressure chambers. During operation of performing printing on a medium to be recorded, the driving part drives the jetting part so that discharging strength is smaller than meniscus breaking strength for breaking meniscus in the jetting part, on the basis of a first driving signal as the driving signal. During flushing operation as non-printing operation, which makes the nozzles dummy-discharge liquid, the driving part drives the jetting part so that the discharging strength is larger than the meniscus breaking strength, on the basis of a second driving signal as the driving signal.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present disclosure relates to a liquid jet head, a liquid jet recording apparatus, and a method for controlling a liquid jet head. [Background technology]

[0002] 2. Description of the Related Art Liquid jet recording apparatuses equipped with liquid jet heads are used in a variety of fields, and various types of liquid jet heads have been developed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-138554 A Summary of the Invention [Problem to be solved by the invention]

[0004] In such liquid jet heads, there is generally a demand for improving the reliability (ejection reliability) of liquid ejection. It is desirable to provide a liquid jet head, a liquid jet recording apparatus, and a method for controlling a liquid jet head that are capable of improving the ejection reliability. [Means for solving the problem]

[0005] A liquid jet head according to an embodiment of the present disclosure includes an ejection unit having a plurality of nozzles for ejecting liquid, a plurality of pressure chambers individually communicating with the plurality of nozzles and each filled with liquid, a liquid supply chamber for supplying liquid into the pressure chambers, and a liquid recovery chamber for recovering liquid from the pressure chambers, and a drive unit for driving the ejection unit based on a drive signal to eject the liquid filled in the pressure chambers from the nozzles. The drive unit drives the ejection unit based on a first drive signal as a drive signal during a printing operation on a recording medium so as to have an ejection strength smaller than a meniscus breakdown strength that breaks a meniscus in the ejection unit, and drives the ejection unit based on a second drive signal as a drive signal during a flushing operation as a non-printing operation in which liquid is dummy ejected from the nozzles so as to have an ejection strength larger than the meniscus breakdown strength. In this disclosure, "meniscus rupture strength" refers to the ejection strength at which the meniscus in the ejection part is ruptured and air bubbles are drawn from the nozzle into the ejection part, forming a gas-liquid two-phase flow of air and air bubbles supplied by circulating between the liquid ejection head and the outside. In addition, in this disclosure, "ejection strength" refers to the "magnitude of energy applied to the ejection part (actuator)".

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

[0007] The control method of the liquid jet head disclosed herein is a method for controlling a liquid jet head including an ejection unit having a plurality of nozzles for ejecting liquid, a plurality of pressure chambers that are individually connected to the plurality of nozzles and filled with liquid, a liquid supply chamber that supplies liquid into the pressure chambers, and a liquid recovery chamber that recovers liquid from the pressure chambers, the method including driving the ejection unit based on a drive signal to eject the liquid filled in the pressure chambers from the nozzles. Ejecting liquid from the nozzles includes driving the ejection unit based on a first drive signal as a drive signal during a printing operation on a recording medium to have an ejection strength smaller than a meniscus destruction strength that destroys a meniscus in the ejection unit, and driving the ejection unit based on a second drive signal as a drive signal during a flushing operation as a non-printing operation in which liquid is dummy ejected from the nozzles to have an ejection strength larger than the meniscus destruction strength. Effect of the Invention

[0008] According to the liquid jet head, the liquid jet recording apparatus, and the method for controlling the liquid jet head according to an embodiment of the present disclosure, it is possible to improve the ejection reliability. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic perspective view illustrating an example of a schematic configuration of a liquid jet recording apparatus according to an embodiment of the present disclosure. [Diagram 2] 2 is a schematic diagram illustrating an example of a schematic configuration of the liquid jet head illustrated in FIG. [Diagram 3] 2 is an exploded perspective view illustrating an example of a detailed configuration of the liquid jet head illustrated in FIG. [Figure 4] 4 is a schematic diagram illustrating an example of a planar configuration of the actuator plate and the like illustrated in FIG. 3. [Diagram 5] 5 is a schematic diagram illustrating an example of a cross-sectional configuration taken along line VV illustrated in FIG. 4. [Figure 6] 6 is a schematic diagram illustrating an example of a cross-sectional configuration taken along line VI-VI illustrated in FIG. 4. [Figure 7]FIG. 6 is an enlarged schematic cross-sectional view of part VII shown in FIG. 5. [Figure 8] 5A to 5C are schematic diagrams illustrating examples of supply paths for potentials supplied from a driving section to a driving electrode. [Figure 9] 5A to 5C are timing charts illustrating examples of waveforms of drive signals during a printing operation and a flushing operation. [Figure 10] 5A to 5C are timing diagrams illustrating examples of various waveforms of a drive signal. [Figure 11] 11A to 11C are diagrams illustrating examples of various methods used during a flushing operation. [Figure 12] 5A and 5B are cross-sectional views illustrating an example of a state of the liquid ejecting head during a flushing operation. [Figure 13] 11 is an exploded perspective view illustrating an example of a detailed configuration of a liquid jet head according to a modified example. [Figure 14] 14 is a schematic diagram illustrating an example of a cross-sectional configuration of the liquid jet head illustrated in FIG. 13. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be made in the following order. 1. Embodiment (Example of a method for setting the ejection strength greater than the meniscus rupture strength during flushing operation) 2. Modification (Example in which a bypass flow path is provided to communicate between the liquid supply chamber and the liquid recovery chamber) 3. Other Modifications

[0011] <1. Preferred embodiment> [A. Overall configuration of Printer 1] 1 is a schematic perspective view showing an example of the general configuration of a printer 1 as a liquid jet recording device according to an embodiment of the present disclosure. The printer 1 is an inkjet printer that uses ink 9, which will be described later, to record (print) images, characters, and the like on recording paper P as a recording medium. Note that this recording medium is not limited to paper, and includes materials capable of being recorded on, such as ceramics and glass.

[0012] As shown in FIG. 1, the printer 1 includes a pair of transport mechanisms 2a, 2b, an ink tank 3, an inkjet head 4, an ink supply pipe 50, and a scanning mechanism 6. These components are housed in a housing 10 having a predetermined shape. In this embodiment, the inkjet head is of a circulation type, in which ink 9 is circulated between the ink tank 3 and the inkjet head 4, as described in detail below. In each drawing used in the description of this specification, the scale of each component is appropriately changed so that each component is of a recognizable size. In addition, in this embodiment, a method for controlling the inkjet head 4 will also be described below.

[0013] Here, the printer 1 corresponds to a specific example of a "liquid jet recording apparatus" in the present disclosure, the inkjet heads 4 (inkjet heads 4Y, 4M, 4C, and 4K described below) correspond to a specific example of a "liquid jet head" in the present disclosure, and the ink 9 corresponds to a specific example of a "liquid" in the present disclosure.

[0014] As shown in Fig. 1, the transport mechanisms 2a and 2b are mechanisms that transport the recording paper P along the transport direction d (X-axis direction). Each of the transport mechanisms 2a and 2b has a grid roller 21, a pinch roller 22, and a drive mechanism (not shown). The drive mechanism is a mechanism that rotates the grid roller 21 around its axis (rotates it in the ZX plane), and is composed of, for example, a motor.

[0015] (Ink Tank 3) The ink tank 3 is a tank that contains ink 9. In this example, as shown in Fig. 1, four types of ink tanks are provided, each of which contains four colors of ink 9: yellow (Y), magenta (M), cyan (C), and black (K). That is, an ink tank 3Y that contains yellow ink 9, an ink tank 3M that contains magenta ink 9, an ink tank 3C that contains cyan ink 9, and an ink tank 3K that contains black ink 9 are provided. These ink tanks 3Y, 3M, 3C, and 3K are arranged side by side in the X-axis direction within the housing 10.

[0016] In addition, the ink tanks 3Y, 3M, 3C, and 3K have the same configuration except for the color of the ink 9 they contain, so they will be collectively referred to as the ink tank 3 in the following description.

[0017] (Inkjet head 4) The inkjet head 4 is a head that ejects (discharges) droplets of ink 9 from a plurality of nozzles (nozzle holes Hn) to be described later onto the recording paper P to record (print) images, characters, and the like. In this example, as shown in FIG. 1, the inkjet head 4 is provided with four types of heads that eject the four colors of ink 9 contained in the ink tanks 3Y, 3M, 3C, and 3K, respectively. That is, the inkjet head 4Y ejects the yellow ink 9, the inkjet head 4M ejects the magenta ink 9, the inkjet head 4C ejects the cyan ink 9, and the inkjet head 4K ejects the black ink 9. These inkjet heads 4Y, 4M, 4C, and 4K are arranged side by side along the Y-axis direction within the housing 10.

[0018] In addition, the inkjet heads 4Y, 4M, 4C, and 4K have the same configuration except for the color of the ink 9 that they use, and therefore will be collectively referred to as the inkjet head 4 below. An example of the detailed configuration of the inkjet head 4 will be described later (FIGS. 2 to 7).

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

[0020] (Scanning mechanism 6) The scanning mechanism 6 is a mechanism for scanning the inkjet head 4 along the width direction (Y-axis direction) of the recording paper P. As shown in Fig. 1, the scanning mechanism 6 has a pair of guide rails 61a, 61b extending along the Y-axis direction, a carriage 62 movably supported on these guide rails 61a, 61b, and a drive mechanism 63 for moving the carriage 62 along the Y-axis direction.

[0021] The drive mechanism 63 has a pair of pulleys 631a, 631b arranged between the guide rails 61a, 61b, an endless belt 632 wound between the pulleys 631a, 631b, and a drive motor 633 that rotates the pulley 631a. In addition, the four types of inkjet heads 4Y, 4M, 4C, and 4K described above are arranged on the carriage 62 in the Y-axis direction.

[0022] The scanning mechanism 6 and the transport mechanisms 2a and 2b described above form a movement mechanism that relatively moves the inkjet head 4 and the recording paper P. The movement mechanism is not limited to this type, and may be, for example, a type in which the inkjet head 4 and the recording medium (the recording paper P) are moved while the inkjet head 4 is fixed, thereby moving the inkjet head 4 and the recording medium separately (a so-called "single pass method").

[0023] [B. Detailed configuration of inkjet head 4] Next, a detailed configuration example of the inkjet head 4 will be described with reference to FIGS.

[0024] FIG. 2 is a schematic diagram showing an example of the outline configuration of the inkjet head 4. For convenience, a cover plate 43, which will be described later, is omitted in FIG. 2. FIG. 3 is an exploded perspective view showing an example of the detailed configuration of the inkjet head 4 shown in FIG. 1. FIG. 4 is a schematic diagram showing a planar configuration example (XY planar configuration example) of the actuator plate 42 and the like shown in FIG. 3. For convenience, FIG. 4 selectively shows the actuator plate 42 of the inkjet head 4. FIG. 5 is a schematic diagram showing a cross-sectional configuration example (ZX cross-sectional configuration example) taken along line VV shown in FIG. 4, and FIG. 6 is a schematic diagram showing a cross-sectional configuration example (ZY cross-sectional configuration example) taken along line VI-VI shown in FIG. 4. FIG. 7 is a schematic cross-sectional view (ZX cross-sectional view) of an enlarged VII portion shown in FIG. 5.

[0025] The inkjet head 4 of this embodiment is a so-called side shoot type inkjet head that ejects ink 9 from the center of a plurality of channels (channels C1 and C2) described below in the extension direction (Y-axis direction). As shown in Figs. 2 to 7, the 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, the actuator plate 42, and the cover plate 43 correspond to a specific example of an "ejection portion" in the present disclosure.

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

[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 the ink 9 (see Figs. 2 to 7). These nozzle holes Hn are arranged in a straight line (along the X-axis direction in this example) at a predetermined interval. As shown in Figs. 3 and 4, the nozzle plate 41 is provided with two nozzle rows (nozzle rows 411, 412) each extending along the X-axis direction. These nozzle rows 411, 412 are arranged at a predetermined interval from each other along the Y-axis direction. In this way, the inkjet head 4 is a two-row type inkjet head.

[0029] The nozzle row 411 has a plurality of nozzle holes H1 formed in a straight line at a predetermined interval along the X-axis direction. Each of these nozzle holes H1 penetrates the nozzle plate 41 along its thickness direction (Z-axis direction) and communicates with an ejection channel C1e in the actuator plate 42 described later. Specifically, as shown in FIG. 4, each nozzle hole H1 is formed so as to be located at the center along the Y-axis direction on the ejection channel C1e. The nozzle holes H1 are formed at the same pitch along the X-axis direction as the ejection channel C1e. From the nozzle holes H1 in the nozzle row 411, ink 9 supplied from the ejection channel C1e is ejected (sprayed), as will be described in detail later.

[0030] Similarly, the nozzle row 412 has a plurality of nozzle holes H2 arranged in a straight line at a predetermined interval along the X-axis direction. Each of these nozzle holes H2 also penetrates the nozzle plate 41 along its thickness direction, and communicates with an ejection channel C2e in the actuator plate 42, which will be described later. Specifically, as shown in FIG. 4, each nozzle hole H2 is formed so as to be located at the center of the ejection channel C2e along the Y-axis direction. The nozzle holes H2 are formed at the same pitch along the X-axis direction as the ejection channel C2e. The ink 9 supplied from the ejection channel C2e is also ejected from the nozzle holes H2 in the nozzle row 412, as will be described later in detail.

[0031] Each of these nozzle holes Hn (H1, H2) is a tapered through hole whose diameter gradually decreases downward (see FIGS. 2, and 5 to 7), and corresponds to a specific example of a "nozzle" in the present 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 is adapted to change the volumes of the discharge channels C1e and C2e, which will be described in detail later. The actuator plate 42 is made of one (single) piezoelectric substrate whose polarization direction is set in one direction along the thickness direction (Z-axis direction) (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 constructed by stacking two piezoelectric substrates having different polarization directions along the thickness direction (Z-axis direction) (so-called chevron type).

[0033] 3 and 4, the actuator plate 42 is provided with two channel rows (channel rows 421 and 422) each extending along the X-axis direction. These channel rows 421 and 422 are disposed at a predetermined interval along the Y-axis direction.

[0034] In such an actuator plate 42, as shown in Fig. 4, the central portion along the X-axis direction (region where the channel rows 421, 422 are formed) serves as the ejection region (jetting region) for the ink 9. Meanwhile, in the actuator plate 42, both ends along the X-axis direction (regions where the channel rows 421, 422 are not formed) serve as non-ejection regions (non-jetting regions) for the ink 9. These non-ejection regions are located on the outer side along the X-axis direction with respect to the above-mentioned ejection regions. Note that both ends along the Y-axis direction of the actuator plate 42 each constitute a tail portion 420 (see Fig. 4).

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

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

[0037] 3 to 5, the channel C1 includes ejection channels C1e for ejecting ink 9 (filled with ink 9) and dummy channels C1d for not ejecting ink 9 (not filled with ink 9). In the channel row 421, these ejection channels C1e and dummy channels C1d are alternately arranged along the X-axis direction via the driving walls Wd described above. Each of the ejection channels C1e individually communicates with each of the nozzle holes H1 in the nozzle plate 41, while each of the dummy channels C1d does not communicate with each of the nozzle holes H1 and is covered from below by the upper surface of the nozzle plate 41 (see FIG. 5).

[0038] 3 and 4, the channel C2 includes an ejection channel C2e for ejecting ink 9 (filled with ink 9) and a dummy channel C2d for not ejecting ink 9 (not filled with ink 9). In the channel row 422, these ejection channels C2e and dummy channels C2d are alternately arranged along the X-axis direction via the driving wall Wd described above. Each of the ejection channels C2e individually communicates with each of the nozzle holes H2 in the nozzle plate 41, while each of the dummy channels C2d does not communicate with each of the nozzle holes H2 and is covered from below by the upper surface of the nozzle plate 41.

[0039] Each of these ejection channels C1e and C2e corresponds to a specific example of a "pressure chamber" in the present disclosure.

[0040] 3 and 4, the ejection channels C1e and dummy channels C1d in the channel C1 are arranged in a staggered manner with respect to the ejection channels C2e and dummy channels C2d in the channel C2. Therefore, in the inkjet head 4, the ejection channels C1e in the channel C1 and the ejection channels C2e in the channel C2 are arranged in a staggered manner. Note that, as shown in FIG. 3, in the actuator plate 42, in the portions corresponding to the dummy channels C1d and C2d, shallow grooves Dd are formed which communicate with the outer ends of the dummy channels C1d and C2d along the Y-axis direction.

[0041] 3 and 6, each ejection channel C1e has an arc-shaped side surface in which the cross-sectional area of ​​each ejection channel C1e gradually decreases from the cover plate 43 side (upper side) toward the nozzle plate 41 side (lower side). Similarly, as shown in Fig. 3, each ejection channel C2e has an arc-shaped side surface in which the cross-sectional area of ​​each ejection channel C2e gradually decreases from the cover plate 43 side toward the nozzle plate 41 side. Note that the arc-shaped side surfaces of the ejection channels C1e and C2e are each formed by, for example, cutting processing using a dicer.

[0042] Here, as shown in Figures 3, 5, and 7, the driving electrodes Ed extending along the Y-axis direction are provided on the opposing inner surfaces of the driving walls Wd. That is, a pair of driving electrodes Ed are arranged facing each other across each driving wall Wd. The driving electrodes Ed include a common electrode Edc (common electrode) provided on the inner surface facing the ejection channels C1e and C2e, and an individual electrode Eda (active electrode) provided on the inner surface facing the dummy channels C1d and C2d. Note that, as shown in Figures 3, 5, and 7, such driving electrodes Ed (common electrode Edc and individual electrode Eda) are formed only up to a middle position in the depth direction (Z-axis direction) on the inner surface of the driving wall Wd.

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

[0044] Here, in the tail portion 420 described above, as shown in Fig. 3, a flexible printed circuit board 493 is mounted for electrically connecting between the driving electrodes Ed and the control unit 49. A wiring pattern (not shown) formed on this flexible printed circuit board 493 is electrically connected to the above-mentioned common terminal and individual terminals. This allows a driving voltage Vd (driving signal Sd) and the like to be applied from the control unit 49 described below to each driving electrode Ed via the flexible printed circuit board 493 (see Fig. 2).

[0045] (B-3. Cover plate 43) 3 and 5 to 7, the cover plate 43 is disposed so as to close the channels C1, C2 (the channel rows 421, 422) in the actuator plate 42. Specifically, the cover plate 43 is bonded to the upper surface of the actuator plate 42 and has a plate-like structure.

[0046] 3 and 6, a pair of supply-side common flow paths Rin1, Rin2 and a pair of recovery-side common flow paths Rout1, Rout2 are formed in the cover plate 43. In addition, as shown in FIG. 6, the cover plate 43 is formed with wall portions W1, W2.

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

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

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

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

[0051] Each of the supply-side common flow paths Rin1 and Rin2 corresponds to a specific example of a "liquid supply chamber" in the present disclosure. Each of the recovery-side common flow paths Rout1 and Rout2 corresponds to a specific example of a "liquid recovery chamber" in the present disclosure.

[0052] In this way, the supply side common flow channel Rin1 and the recovery side common flow channel Rout1 are connected to each ejection channel C1e via the supply slit Sin1 and the recovery slit Sout1, respectively (see Figs. 3 and 6). Also, the supply slit Sin1 and the recovery slit Sout1 are each a through hole through which the ink 9 flows between the ejection channel C1e and the supply side common flow channel Rin1. In detail, the supply side common flow channel Rin1 supplies the ink 9 into the ejection channel C1e via the supply slit Sin1, and the recovery side common flow channel Rout1 recovers the ink 9 from the ejection channel C1e via the recovery slit Sout1 (see the dashed arrow in Fig. 6). On the other hand, neither the supply side common flow channel Rin1 nor the recovery side common flow channel Rout1 is connected to each dummy channel C1d. Specifically, each dummy channel C1d is closed by the bottom of the supply side common flow channel Rin1 and the recovery side common flow channel Rout1.

[0053] Similarly, the supply side common flow channel Rin2 and the recovery side common flow channel Rout2 are connected to each ejection channel C2e via the supply slit Sin2 and the recovery slit Sout2, respectively (see FIG. 3). Also, the supply slit Sin2 and the recovery slit Sout2 are each a through hole through which the ink 9 flows between the ejection channel C2e and the supply side common flow channel Rin2. In detail, the supply side common flow channel Rin2 supplies the ink 9 into the ejection channel C2e via the supply slit Sin2, and the recovery side common flow channel Rout2 recovers the ink 9 from the ejection channel C2e via the recovery slit Sout2. On the other hand, neither the supply side common flow channel Rin2 nor the recovery side common flow channel Rout2 are connected to each dummy channel C2d (see FIG. 6). Specifically, each dummy channel C2d is closed by the bottom of the supply side common flow channel Rin2 and the recovery side common flow channel Rout2 (see FIG. 6).

[0054] (B-4. Drive unit 49) 2, the drive unit 49 drives the ejection of the ink 9 using a drive signal Sd (drive voltage Vd). At this time, the drive unit 49 outputs the drive signal Sd (drive voltage Vd) based on various data (signals) supplied from a print control unit (not shown) in the printer 1 (inside the inkjet head 4).

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

[0056] Although details will be described later, the drive unit 49 drives the actuator plate 42 based on a first drive signal Sd1 as the drive signal Sd during a printing operation on the recording paper P (recording medium). On the other hand, the drive unit 49 drives the actuator plate 42 based on a second drive signal Sd2 as the drive signal Sd during a flushing operation (non-printing operation) in which ink 9 is dummy-ejected from the nozzle holes Hn.

[0057] [C. Detailed configuration of drive voltage Vd and drive signal Sd] Next, a detailed configuration example of the above-mentioned drive voltage Vd and drive signal Sd (Sd1, Sd2) will be described with reference to FIGS.

[0058] Fig. 8 is a schematic diagram showing an example of a supply path of each potential supplied from the driving unit 49 to the driving electrode Ed (individual electrode Eda and common electrode Edc). Specifically, Fig. 8 shows an example of a supply path for the 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). Although not shown in Fig. 8 for convenience, the same applies to an example of a supply path for the channel C2 (example of the supply path for the individual potential Vda and common potential Vdc).

[0059] Fig. 9 is a schematic timing diagram showing an example of the waveform of the drive signal Sd during the printing operation and the flushing operation. Specifically, Fig. 9(A) shows an example of the waveform of the drive signal Sd (the above-mentioned first drive signal Sd1) during the printing operation, and Fig. 9(B) shows an example of the waveform of the drive signal Sd (the above-mentioned second drive signal Sd2) during the flushing operation. Fig. 10 is a schematic timing diagram showing various examples of the waveform of the drive signal Sd.

[0060] In both Figures 9 and 10, the vertical axis represents the voltage value of the driving voltage Vd (corresponding to the potential difference between the individual potential Vda and the common potential Vdc described above: Vd=Vda-Vdc), and the horizontal axis represents time t. The magnitude of the driving voltage Vd corresponds to the volume of the ejection channels C1e and C2e described above. When the driving voltage Vd is a positive (+) value, or a negative (-) value, it indicates that the volume is expanded or contracted relative to the reference value, respectively (see Figure 9).

[0061] Incidentally, in the example shown in Fig. 9, the common potential Vdc is set to a predetermined positive potential (Vdc>0) so that the drive voltage Vd (potential difference between the individual potential Vda and the common potential Vdc) is set to a negative value (Vd<0), but this is not limiting. 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 driving case, it is possible to perform driving (pressure fluctuation in the actuator plate 42) similar to the driving example shown in Fig. 9.

[0062] In each example shown in FIG. 9(A), FIG. 9(B), and FIG. 10(A) to FIG. 10(D), the driving signal Sd (Sd1, Sd2) is a signal having multiple pulses (pulses p1, p2) in one cycle (driving cycle Td described below) (a signal to which the so-called "multi-pulse method" is applied). The pulse p1 is a pulse (expansion pulse) for expanding the volume of the ejection channels C1e, C2e, and the pulse p2 is a pulse (contraction pulse) for contracting the volume of the ejection channels C1e, C2e. In each example shown in FIG. 10(A) to FIG. 10(D), among the multiple pulses in one cycle (driving cycle Td), the first pulse is the pulse p1, and the last pulse is the pulse p2. However, the first pulse in the driving cycle Td may be either the pulse p1 (expansion pulse) or the pulse p2 (contraction pulse). In addition, in Figures 10(A) to 10(D), the last pulse p1 in the drive period Td is shown as a pulse p1e (final expansion pulse), and the last pulse p2 in the drive period Td is shown as a pulse p2e (final contraction pulse).

[0063] Here, the above-mentioned "one cycle (= drive cycle Td)" means the time interval for forming one pixel (dot) on the recording paper P (recording medium). The drive frequency fd in the drive signal Sd shown in Fig. 10(A) to Fig. 10(D) is the reciprocal of this drive cycle Td (fd=1 / Td). In other words, this drive frequency fd corresponds to the number of pixels (dots) formed per second on the recording paper P (recording medium).

[0064] [D. Example of operation during printing and flushing] Next, examples of driving during the above-mentioned printing operation and flushing operation will be described in detail with reference to Fig. 11 in addition to Fig. 8 to Fig. 10. Fig. 11 shows, in a table, various examples of methods (examples of methods A to D described later) during the flushing operation shown in Fig. 9(B).

[0065] 9A, the drive unit 49 performs the ejection drive (the drive operation for the actuator plate 42) as follows based on the first drive signal Sd1 described above. That is, during this printing operation, the drive unit 49 performs the ejection drive based on the first drive signal Sd1 so as to achieve an ejection intensity Pj1 that is smaller than the meniscus destruction intensity Pmb that destroys the meniscus in the ejection channels C1e and C2e (Pj1 <Pmb)。

[0066] 9B, the drive unit 49 performs the ejection drive based on the second drive signal Sd2 described above as follows: That is, during the flushing operation, the drive unit 49 performs the ejection drive based on the second drive signal Sd2 so as to achieve the ejection strength Pj2 that is greater than the meniscus destruction strength Pmb described above (Pj2>Pmb).

[0067] In this embodiment, the term "meniscus rupture strength" refers to the ejection strength at which the meniscus in the ejection channels C1e, C2e is broken and air bubbles are drawn from the nozzle holes Hn into the ejection channels C1e, C2e, forming a gas-liquid two-phase flow (see FIG. 12, described later) between the ink 9 circulated between the inkjet head 4 and the outside (ink tank 3) and the air bubbles. In this embodiment, the term "ejection strength" refers to the "magnitude of energy applied to the actuator (actuator plate 42)". The definitions of "meniscus rupture strength" and "ejection strength" are the same in each of the modified examples, described later.

[0068] Here, as a method for achieving (ejection strength Pj2>meniscus rupture strength Pmb) during such a flushing operation, for example, each of the methods (methods A to D) shown in FIG. 11 can be mentioned.

[0069] First, in method A, as in the example of FIG. 9B described above, the drive unit 49 increases the number of pulses Np2 (the number of pulses p1, p2 included in the drive period Td) in the second drive signal Sd2 to be greater than the number of pulses in the first drive signal Sd1 during the printing operation. Specifically, the drive unit 49 increases the number of pulses Np2 in the second drive signal Sd2 during the flushing operation to be greater than the threshold number of pulses Nth corresponding to the meniscus breakdown strength Pmb (Np2>Nth). In method A, the number of pulses Np2 is set in this manner, so that the ejection strength Pj2 during the flushing operation is set to be greater than the meniscus breakdown strength Pmb, as described above.

[0070] In method B, the drive unit 49 increases the drive voltage Vd=Vd2 in the second drive signal Sd2 to be greater than the drive voltage Vd in the first drive signal Sd1 during the printing operation. Specifically, the drive unit 49 increases the drive voltage Vd2 in the second drive signal Sd2 during the flushing operation to be greater than the threshold voltage Vth corresponding to the meniscus rupture strength Pmb (Vd2>Vth). In method B, the drive voltage Vd2 is set in this manner, so that the ejection strength Pj2 during the flushing operation is set to be greater than the meniscus rupture strength Pmb, as described above.

[0071] In method C, the drive unit 49 increases the drive frequency fd=fd2 of the second drive signal Sd2 to be higher than the drive frequency fd of the first drive signal Sd1 during the printing operation. Specifically, the drive unit 49 increases the drive frequency fd2 of the second drive signal Sd2 during the flushing operation to be higher than the threshold frequency fth corresponding to the meniscus rupture strength Pmb (fd2>fth). In method C, the drive frequency Vf2 is set in this manner, so that the ejection strength Pj2 during the flushing operation is set to be higher than the meniscus rupture strength Pmb, as described above.

[0072] In method D, the driving unit 49 sets the pulse width Wp2 of the pulses (pulses p1, p2) included in the second driving signal Sd2 during the flushing operation to the resonance period (AP: Acoustic Period) (Wp2=AP). In method D, by setting the pulse width Wp2 in this manner, the ejection strength Pj2 during the flushing operation is set to be greater than the meniscus breakdown strength Pmb, as described above.

[0073] Incidentally, this AP corresponds to half the period of the natural vibration period of the ink 9 in the ejection channels C1, C2e (1AP = (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 becomes maximum when ejecting one normal drop of ink 9 (ejecting one drop). Furthermore, this AP is determined, for example, by the shape of the ejection channels C1e, C2e and the physical properties of the ink 9 (specific gravity, etc.).

[0074] The above threshold voltage Vth corresponds to a specific example of a "first threshold" in the present disclosure. The above threshold frequency fth corresponds to a specific example of a "second threshold" in the present disclosure. The above threshold pulse number Nth corresponds to a specific example of a "third threshold" in the present disclosure.

[0075] [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. Note that, in the initial state, each of the four types of ink tanks 3 (3Y, 3M, 3C, 3K) shown in Fig. 1 is fully filled with ink 9 of the corresponding color (four colors). The ink 9 in the ink tanks 3 is filled in the inkjet head 4 via the ink supply pipe 50.

[0076] In this initial state, when the printer 1 is operated, the grid rollers 21 in the transport mechanisms 2a and 2b rotate, and the recording paper P is transported between the grid rollers 21 and the pinch rollers 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 reciprocates along the width direction (Y-axis direction) of the recording paper P while being 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, and the like onto the recording paper P.

[0077] (B. Detailed Operation of Inkjet Head 4) Next, a detailed operation (operation by ejection driving) of the inkjet head 4 will be described.

[0078] First, in the inkjet head 4, the ink 9 is ejected using the shear mode as follows. In other words, the drive unit 49 drives the actuator plate 42 to eject ink using the drive signal Sd described above, so that the ink 9 filled in the ejection channels C1e and C2e is ejected from the nozzle holes Hn.

[0079] During such ejection driving, the drive unit 49 applies a drive voltage Vd (drive signal Sd) to the drive electrodes Ed (common electrode Edc and individual electrodes Eda) in the actuator plate 42. Specifically, the drive unit 49 applies the drive voltage Vd to each of the drive electrodes Ed (common electrode Edc and individual electrodes Eda) arranged on a pair of drive walls Wd that define the ejection channels C1e and C2e. This causes the pair of drive walls Wd to deform so as to protrude toward the non-ejection channels C1d and C2d adjacent to the ejection channels C1e and C2e.

[0080] As described above, the actuator plate 42 has a polarization direction set in one direction, and the drive electrode Ed is formed only up to a middle position in the depth direction on the inner surface of the drive wall Wd. Therefore, when the control unit 49 applies the drive voltage Vd, the drive wall Wd is bent and deformed into a V shape around the middle position in the depth direction of the drive wall Wd. This bending and deformation of the drive wall Wd causes the ejection channels C1e and C2e to deform as if they are expanding (see the expansion direction d11 shown in FIG. 7).

[0081] Incidentally, when the actuator plate 42 is not of the cantilever type but of the chevron type, the driving wall Wd is bent and deformed in a V shape as follows. That is, in the case of the chevron type, the polarization direction of the actuator plate 42 is different along the thickness direction (the two piezoelectric substrates are laminated), and the driving electrode Ed is formed on the inner surface of the driving wall Wd over the entire depth direction. Therefore, when the driving voltage Vd is applied by the control unit 49, the driving wall Wd is bent and deformed in a V shape around the middle position of the driving wall Wd in the depth direction. As a result, even in this case, the ejection channels C1e and C2e are deformed as if they are expanding due to the bending and deformation of the driving wall Wd (see the expansion direction d11 shown in FIG. 7).

[0082] In this way, the volume of the ejection channels C1e, C2e increases due to bending deformation caused by the piezoelectric thickness slip effect at the pair of driving walls Wd. As the volume of the ejection channels C1e, C2e increases, the ink 9 stored in the supply-side common ink chambers Rin1, Rin2 is guided into the ejection channels C1e, C2e through the supply slits Sin1, Sin2 (see, for example, the dashed arrows in FIG. 6).

[0083] Next, the ink 9 guided into the ejection channels C1e, C2e in this manner becomes a pressure wave and propagates inside the ejection channels C1e, C2e. Then, at the timing when this pressure wave reaches the nozzle hole Hn of the nozzle plate 41 (or at a timing close to that), the drive voltage Vd applied to the drive electrode Ed becomes 0 (zero) V. As a result, the drive wall Wd returns to its original state from the bent and deformed state described above, and the volume of the ejection channels C1e, C2e that had temporarily increased returns to its original volume (for example, see the contraction direction db shown in FIG. 7).

[0084] In this way, in the process of the volumes of the ejection channels C1e, C2e returning to their original values, the pressure inside the ejection channels C1e, C2e increases, and the ink 9 in the ejection channels C1e, C2e is pressurized. As a result, droplets of ink 9 are ejected through the nozzle holes Hn to the outside (toward the recording paper P, etc.) (see FIGS. 2, 5 to 7). In this way, the ink jet head 4 performs an ejection operation (ejection operation) of the ink 9, and as a result, a recording operation (printing operation) of images, characters, etc. on the recording paper P is performed.

[0085] A part of the ink 9 filled in the ejection channels C1e, C2e is recovered into the recovery side common ink chambers Rout1, Rout2 through the recovery slits Sout1, Sout2 (see, for example, the dashed arrows in FIG. 6). The ink 9 recovered into these recovery side common ink chambers Rout1, Rout2 is returned from the inkjet head 4 into the ink tank 3 through the ink supply pipe 50. In this way, the ink 9 is circulated.

[0086] (C. Regarding poor discharge caused by air bubbles or foreign matter) In general, in inkjet heads, in order to recover from ejection failures caused by foreign matter such as air bubbles or dust in the filled ink, an operation of ejecting ink from the nozzle holes (flushing operation as a non-printing operation) is performed separately from the printing operation. During such a flushing operation, the ejection strength of the ink is increased to increase the pressure fluctuation and oscillation in the ejection channel (ink chamber), thereby increasing the effect of removing air bubbles, foreign matter, etc.

[0087] However, if the ejection strength is too strong, the meniscus will be destroyed inside the inkjet head. Once the meniscus is destroyed, it will not return to its original state in a non-circulation type inkjet head, and ink will not be ejected even if the drive waveform for printing is applied. In other words, in such a case, ejection failure will occur due to nozzle missing. For this reason, in a non-circulation type inkjet head, for example, a separate operation such as refilling the ink is generally required to recover from the ejection failure.

[0088] For these reasons, it is desirable to propose a method that can effectively suppress ejection defects caused by air bubbles or foreign matter remaining in the ink and improve the ejection reliability of inkjet heads.

[0089] (D. Driving Operation, Actions and Effects of the Present Embodiment) Therefore, in the inkjet head 4 of the present embodiment, during the flushing operation, the drive unit 49 performs the ejection drive based on the second drive signal Sd2 as the drive signal Sd so as to achieve the ejection intensity Pj2 greater than the meniscus rupture strength Pmb described above. Specifically, the drive unit 49 performs the ejection drive using, for example, each of the methods shown in FIG. 11 described above so as to achieve the ejection intensity Pj2 greater than the meniscus rupture strength Pmb.

[0090] FIG. 12 is a schematic cross-sectional view (YZ cross-sectional view) illustrating an example of the state of the ink-jet head 4 during such a flushing operation.

[0091] In this embodiment, as described above, the meniscus in the ejection channels C1e and C2e is destroyed during the flushing operation, which results in the following: That is, for example, as shown by the dashed arrow Pa in Fig. 12, the air bubbles Ab are drawn from the nozzle holes Hn into the ejection channels C1e and C2e, and a gas-liquid two-phase flow is formed by the ink 9 and the air bubbles Ab. In this embodiment, the formation of such a gas-liquid two-phase flow increases pressure fluctuations and oscillations in the ejection channels C1e and C2e, and fluctuations in the liquid level of the ink 9, and therefore the effect of removing air bubbles, foreign matter, and the like that remain in the ink 9 is increased.

[0092] As described above, in this embodiment, the ink 9 is circulated using the supply-side common flow paths Rin1, Rin2 and the recovery-side common flow paths Rout1, Rout2, which results in the following: Even if the meniscus is destroyed during the flushing operation, unlike the configuration in which the ink 9 does not circulate as described above, no refilling operation of the ink 9 is performed, and ejection defects due to missing nozzles and the like are avoided.

[0093] For these reasons, in this embodiment, ejection defects caused by air bubbles Ab or foreign matter remaining in the ink 9 during printing operation are effectively suppressed, thereby making it possible to improve the ejection reliability of the inkjet head 4.

[0094] Furthermore, in this embodiment, it is possible to effectively remove air bubbles Ab, foreign matter, and the like, without changing various parameters (such as back pressure and head value) related to the circulation of the ink 9.

[0095] Furthermore, in this embodiment, the methods (methods A to D) shown in Fig. 11 are used as methods for achieving the above-mentioned (ejection intensity Pj2>meniscus rupture strength Pmb) during the flushing operation, so that the following is true: It becomes possible to easily adjust the ejection intensity Pj2 using general ejection parameters (the number of pulses Np2 included in the drive cycle Td, the drive voltage Vd, the drive frequency fd, and the pulse width Wp2 of the pulses p1, p2 included in the second drive signal Sd2).

[0096] <2. Modifications> Next, a modification of the above embodiment will be described. Note that the same components as those in the embodiment will be given the same reference numerals, and the description will be omitted as appropriate.

[0097] (composition) Fig. 13 is an exploded perspective view showing a detailed configuration example of an inkjet head 4a according to a modified example, and Fig. 14 is a schematic diagram showing a cross-sectional configuration example (YZ cross-sectional configuration example) of the inkjet head 4a shown in Fig. 13.

[0098] As shown in Figures 13 and 14, the inkjet head 4a of this modified example corresponds to the inkjet head 4 of the embodiment in which a cover plate 43a, which will be described below, is provided instead of the cover plate 43, and the other configurations are similar.

[0099] The inkjet head 4a corresponds to a specific example of a "liquid jet head" in the present disclosure, and a printer including the inkjet head 4a corresponds to a specific example of a "liquid jet recording device" in the present disclosure. The nozzle plate 41, the actuator plate 42, and the cover plate 43a correspond to a specific example of an "ejection unit" in the present disclosure.

[0100] A cover plate 43a of this modification corresponds to the cover plate 43 of the embodiment further provided with bypass flow paths Rb1, Rb2, which will be described below, and the other configurations are similar.

[0101] As shown in Figs. 13 and 14, the bypass flow path Rb1 is a flow path that communicates the supply side common ink chamber Rin1 and the recovery side common ink chamber Rout1. Similarly, the bypass flow path Rb2 is a flow path that communicates the supply side common ink chamber Rin2 and the recovery side common ink chamber Rout2, as shown in Fig. 13. Such bypass flow paths Rb1 are provided near both ends of the supply side common ink chamber Rin1 and the recovery side common ink chamber Rout1 in the extension direction (X-axis direction) (see Fig. 13). Similarly, the bypass flow paths Rb2 are provided near both ends of the supply side common ink chamber Rin2 and the recovery side common ink chamber Rout2 in the extension direction (X-axis direction) (see Fig. 13).

[0102] (Action and effect) In this modified configuration, in addition to the effects of the embodiment, the following effects can be obtained, for example.

[0103] That is, in the inkjet head 4a of this modified example, since the above-mentioned bypass flow paths Rb1 and Rb2 are provided, the air bubbles Ab drawn into the ejection channels C1e and C2e during the flushing operation can pass through these bypass flow paths Rb1 and Rb2 (see, for example, the dashed arrows in FIG. 14). Therefore, it is easy to prevent the air bubbles Ab drawn into the ejection channels C1e and C2e from invading other ejection channels C1e and C2e via, for example, the supply-side common ink chambers Rin1 and Rin2. As a result, ejection failures due to air bubbles Ab or foreign matter remaining in the ink 9 are more effectively suppressed, and the ejection reliability of the inkjet head 4a can be further improved.

[0104] <3. Other Modifications> While the present disclosure has been described above by way of embodiments and modified examples, the present disclosure is not limited to these embodiments and can be modified in various ways.

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

[0106] Specifically, for example, in the above-mentioned embodiments, specific examples of the type and number of pulses contained in the drive signal Sd, the magnitude of the drive voltage Vd and drive frequency fd, the setting value of the pulse width, etc. are given and described, but are not limited to those described in the above-mentioned embodiments.

[0107] In addition, various types of inkjet head structures can be applied. That is, for example, in the above embodiment and the like, a so-called side shoot type inkjet head that ejects ink 9 from the center of the actuator plate in the extension direction of each ejection channel has been described as an example. However, the present invention is not limited to this example, and may be, for example, a so-called edge shoot type inkjet head that ejects ink 9 along the extension direction of each ejection channel.

[0108] Furthermore, the printer system is not limited to the systems described in the above embodiments, and various systems, such as a MEMS (Micro Electro Mechanical Systems) system, can be applied.

[0109] In addition, in the above embodiment, etc., a specific example is given of a method for achieving (ejection strength Pj2>meniscus rupture strength Pmb) during the flushing operation, but the method is not limited to the methods given in the above embodiment, etc., and other methods may be used. Also, for example, two or more of the methods given in the embodiment, etc. may be used in appropriate combination.

[0110] Furthermore, the series of processes described in the above embodiments may be performed by hardware (circuits) or software (programs). When performed by software, the software is composed of a group of programs for causing a computer to execute each function. Each program may be, for example, pre-installed in the computer and used, or may be installed in the computer from a network or a recording medium and used.

[0111] Furthermore, in the above embodiment, the printer 1 (inkjet printer) has been described as a specific example of the "liquid jet recording apparatus" of the present disclosure, but the present disclosure is not limited to this example and can be applied to other apparatuses other than inkjet printers. In other words, the "liquid jet head" (inkjet head) of the present disclosure may be applied to other apparatuses other than inkjet printers. Specifically, for example, the "liquid jet head" of the present disclosure may be applied to apparatuses such as facsimiles and on-demand printers.

[0112] In addition, the various examples described above may be applied in any combination.

[0113] It should be noted that the effects described in this specification are merely examples and are not limiting, and other effects may also be obtained.

[0114] The present disclosure can also be configured as follows. (1) an ejection unit including a plurality of nozzles for ejecting liquid, a plurality of pressure chambers each in communication with the plurality of nozzles and filled with the liquid, a liquid supply chamber for supplying the liquid into the pressure chamber, and a liquid recovery chamber for recovering the liquid from the pressure chamber; a drive unit that drives the ejection unit based on a drive signal to eject the liquid filled in the pressure chamber from the nozzle; Equipped with The drive unit is During a printing operation on a recording medium, the ejection unit is driven based on a first drive signal as the drive signal so that the ejection strength is smaller than a meniscus destruction strength that destroys a meniscus in the ejection unit, and During a flushing operation as a non-printing operation in which the liquid is dummy-ejected from the nozzle, the ejection unit is driven based on a second drive signal as the drive signal so as to have an ejection strength greater than the meniscus rupture strength. Liquid injection head. (2) The drive unit is By increasing the drive voltage of the second drive signal above a first threshold value corresponding to the meniscus rupture strength, The ejection strength is set to be greater than the meniscus rupture strength. The liquid jet head according to (1) above. (3) The drive unit is By increasing the drive frequency of the second drive signal above a second threshold value corresponding to the meniscus rupture strength, The ejection strength is set to be greater than the meniscus rupture strength. The liquid jet head according to (1) or (2) above. (4) The drive unit is By increasing the number of pulses included in one period of the second drive signal to be greater than a third threshold value corresponding to the meniscus rupture strength, The ejection strength is set to be greater than the meniscus rupture strength. The liquid jet head according to any one of (1) to (3) above. (5) The drive unit is By setting the pulse width of the pulse included in the second drive signal to the resonance period (AP), The ejection strength is set to be greater than the meniscus rupture strength. The liquid jet head according to any one of (1) to (4) above. (6) The ejection section further includes a bypass flow path that communicates the liquid supply chamber with the liquid recovery chamber. The liquid jet head according to any one of (1) to (5) above. (7) A liquid jet head according to any one of (1) to (6) above is provided. Liquid jet recording device. (8) A method for controlling a liquid ejection head including an ejection unit having a plurality of nozzles that eject liquid, a plurality of pressure chambers that are individually connected to the plurality of nozzles and are filled with the liquid, a liquid supply chamber that supplies the liquid into the pressure chambers, and a liquid recovery chamber that recovers the liquid from the pressure chambers, the method comprising the steps of: the ejection unit is driven based on a drive signal to eject the liquid filled in the pressure chamber from the nozzle; The ejection of the liquid from the nozzle includes: driving the ejection unit with a discharge intensity smaller than a meniscus breakdown intensity that breaks a meniscus in the ejection unit, based on a first drive signal as the drive signal, during a printing operation on a recording medium; during a flushing operation as a non-printing operation in which the liquid is dummy-ejected from the nozzle, driving the ejection unit so as to have an ejection strength greater than the meniscus rupture strength based on a second drive signal as the drive signal; A method for controlling a liquid ejection head, comprising: [Explanation of symbols]

[0115] 1... printer, 10... housing, 2a, 2b... transport mechanism, 21... grid roller, 22... pinch roller, 3 (3Y, 3M, 3C, 3K)... ink tank, 4 (4Y, 4M, 4C, 4K), 4a... inkjet head, 41... nozzle plate, 411, 412... nozzle row, 42... actuator plate, 420... tail, 421, 422... channel row, 43, 43a... cover plate, 49... drive unit, 493... head Flexible printed circuit board, 50... ink supply pipe, 6... scanning mechanism, 61a, 61b... guide rails, 62... carriage, 63... drive mechanism, 631a, 631b... pulleys, 632... endless belt, 633... drive motor, 9... ink, P... recording paper, d... conveyance direction, Hn, H1, H2... nozzle holes, Dd... shallow groove portion, Rin1, Rin2... supply side common flow path, Rout1, Rout2... recovery side common flow path, Rb1, Rb2... biaxially extending portion, Path flow path, Sin1, Sin2...supply slit, Sout1, Sout2...recovery slit, W1, W2...wall, Sd...drive signal, Sd1...first drive signal, Sd2...second drive signal, Vd, Vd2...drive voltage, Vda...individual potential (active potential), Vdc...common potential (common potential), Vth...threshold voltage, C1, C2...channel, C1e, C2e...ejection channel, C1d, C2d...dummy channel (non-ejection channel) 1, Wd...driving wall, Ed...driving electrode, Eda...individual electrode (active electrode), Edc...common electrode (common electrode), da...direction of expansion, db...direction of contraction, Ab...bubble, Pj1, Pj2...ejection strength, Pmb...meniscus rupture strength, p1, p2, p1e, p2e...pulse, Wp2...pulse width, Td...driving period, fd, fd2...driving frequency, fth...threshold frequency, Np2...number of pulses, Nth...threshold number of pulses, t...time.

Claims

1. an ejection unit including a plurality of nozzles for ejecting liquid, a plurality of pressure chambers each in communication with the plurality of nozzles and filled with the liquid, a liquid supply chamber for supplying the liquid into the pressure chamber, and a liquid recovery chamber for recovering the liquid from the pressure chamber; a drive unit that drives the ejection unit based on a drive signal to eject the liquid filled in the pressure chamber from the nozzle; Equipped with The drive unit is During a printing operation on a recording medium, the ejection unit is driven based on a first drive signal as the drive signal so that the ejection strength is smaller than a meniscus destruction strength that destroys a meniscus in the ejection unit, and During a flushing operation as a non-printing operation in which the liquid is dummy-ejected from the nozzle, the ejection unit is driven based on a second drive signal as the drive signal so as to have an ejection strength greater than the meniscus destruction strength. Liquid injection head.

2. The drive unit is Increasing the drive voltage of the second drive signal above a first threshold value corresponding to the meniscus rupture strength; The ejection strength is set to be greater than the meniscus rupture strength. The liquid jet head according to claim 1 .

3. The drive unit is By increasing the drive frequency of the second drive signal above a second threshold value corresponding to the meniscus rupture strength, The ejection strength is set to be greater than the meniscus rupture strength. The liquid jet head according to claim 1 .

4. The drive unit is By increasing the number of pulses included in one period of the second drive signal to be greater than a third threshold value corresponding to the meniscus rupture strength, The ejection strength is set to be greater than the meniscus rupture strength. The liquid jet head according to claim 1 .

5. The drive unit is By setting the pulse width of the pulse included in the second drive signal to the resonance period (AP), The ejection strength is set to be greater than the meniscus rupture strength. The liquid jet head according to claim 1 .

6. The ejection section further includes a bypass flow path that communicates the liquid supply chamber with the liquid recovery chamber. The liquid jet head according to claim 1 .

7. The liquid jet head according to claim 1 is provided Liquid jet recording device.

8. A method for controlling a liquid ejection head including an ejection unit having a plurality of nozzles that eject liquid, a plurality of pressure chambers that are individually connected to the plurality of nozzles and are filled with the liquid, a liquid supply chamber that supplies the liquid into the pressure chambers, and a liquid recovery chamber that recovers the liquid from the pressure chambers, the method comprising the steps of: the ejection unit is driven based on a drive signal to eject the liquid filled in the pressure chamber from the nozzle; The ejection of the liquid from the nozzle includes: driving the ejection unit with a discharge intensity smaller than a meniscus destruction intensity for destroying a meniscus in the ejection unit based on a first drive signal as the drive signal during a printing operation on a recording medium; during a flushing operation as a non-printing operation in which the liquid is dummy-ejected from the nozzle, driving the ejection unit so as to have an ejection strength greater than the meniscus rupture strength based on a second drive signal as the drive signal; A method for controlling a liquid ejection head, comprising:

Images