Method for adjusting ejection characteristics of a liquid jet head, liquid jet head, and liquid jet recording apparatus

Abstract

A method for adjusting the ejection characteristics of a liquid jet head, which can easily improve print quality, is provided. [Solution] A method for adjusting the ejection characteristics of a liquid ejection head according to one embodiment of the present disclosure is a method for adjusting the ejection characteristics of liquid in a liquid ejection head equipped with an ejection section having a plurality of nozzles that eject liquid and a piezoelectric substrate that includes a plurality of pressure chambers that are individually connected to the plurality of nozzles and are each filled with liquid, and when a voltage waveform is applied to the piezoelectric substrate on a pressure chamber basis, a predetermined correction process is performed on the voltage waveform, thereby individually adjusting the tilt of the polarization direction within the piezoelectric substrate from the initial state on a pressure chamber basis.

Description

[Technical Field]

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

[0002] Liquid jet recording apparatuses equipped with liquid jet heads are used in a variety of fields, and various methods have been developed for liquid jet heads and methods for adjusting their characteristics (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-160823 Summary of the Invention [Problem to be solved by the invention]

[0004] In such liquid jet heads, it is generally required to easily achieve improved print quality. It is desirable to provide a method for adjusting the ejection characteristics of a liquid jet head, a liquid jet head, and a liquid jet recording apparatus that can easily achieve improved print quality. [Means for solving the problem]

[0005] A method for adjusting ejection characteristics of a liquid jet head according to an embodiment of the present disclosure is a method for adjusting ejection characteristics of a liquid in a liquid jet head including an ejection unit having a plurality of nozzles that eject liquid and a piezoelectric substrate including a plurality of pressure chambers that are individually connected to the plurality of nozzles and are each filled with liquid, the method comprising: For characteristic adjustment Voltage waveform By pressure chamber When applying the voltage, a predetermined correction process is performed on the voltage waveform to change the polarization direction in the piezoelectric substrate. of itself The tilt from the initial state is Before the ejection operation in which the pressure chamber is deformed to eject the liquid from the nozzle, Individual pressure chamber units advanceIt is designed to be adjustable.

[0006] A liquid jet head according to an embodiment of the present disclosure includes an ejection unit having a plurality of nozzles that eject liquid and a piezoelectric substrate including a plurality of pressure chambers that are individually connected to the plurality of nozzles and are each filled with liquid; For characteristic adjustment Voltage waveform By pressure chamber The voltage application unit applies a predetermined correction process to the voltage waveform to correct the polarization direction in the piezoelectric substrate. of itself The tilt from the initial state is Before the ejection operation in which the pressure chamber is deformed to eject the liquid from the nozzle, Individual pressure chamber units advance Adjust.

[0007] 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. [Effects of the Invention]

[0008] According to the method for adjusting the ejection characteristics of a liquid jet head, the liquid jet head, and the liquid jet recording apparatus according to an embodiment of the present disclosure, it is possible to easily achieve an improvement in print quality. [Brief explanation 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. [Figure 2] 2 is a schematic diagram illustrating an example of a schematic configuration of the liquid jet head illustrated in FIG. 1. [Figure 3] 2 is an exploded perspective view illustrating an example of a detailed configuration of the liquid jet head illustrated in FIG. 1. 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. [Figure 5] 5 is a schematic diagram illustrating an example of a cross-sectional configuration taken along line VV shown in FIG. 4. [Figure 6] 6 is a schematic diagram illustrating an example of a cross-sectional configuration taken along line VI-VI shown in FIG. 4. [Figure 7]FIG. 6 is an enlarged schematic cross-sectional view of part VII shown in FIG. 5. [Figure 8] 5A and 5B are schematic diagrams illustrating examples of supply paths for potentials supplied from a driving section to a driving electrode. [Figure 9] 5A and 5B are timing diagrams schematically illustrating examples of waveforms of drive signals during a printing operation. [Figure 10] FIG. 10 is a timing diagram schematically illustrating an example of a voltage waveform applied when adjusting the polarization direction. [Figure 11] FIG. 1 is a schematic cross-sectional view illustrating an example of the schematic configuration of an inkjet head according to a comparative example. [Figure 12] 5A to 5C are schematic cross-sectional views illustrating an example of operation during a printing operation of the inkjet head according to the embodiment. [Figure 13] 10 is a flowchart illustrating an example of a process for adjusting a polarization direction according to an embodiment. [Figure 14] 14 is a schematic cross-sectional view illustrating an example of operation when adjusting the polarization direction shown in FIG. 13. FIG. [Figure 15] 14 is a schematic cross-sectional view illustrating another example of the operation when adjusting the polarization direction shown in FIG. 13. FIG. [Figure 16] FIG. 14 is a characteristic diagram illustrating an example of the relationship between nozzle position and ejection characteristics before the polarization direction is adjusted as shown in FIG. [Figure 17] FIG. 14 is a characteristic diagram illustrating an example of the relationship between nozzle position and ejection characteristics after the polarization direction is adjusted as shown in FIG. [Figure 18] FIG. 10 is a schematic cross-sectional view illustrating an example of the general configuration of an inkjet head according to a modified example. [Figure 19] 19A and 19B are schematic cross-sectional views illustrating an example of operation during a printing operation of the inkjet head illustrated in FIG. 18. [Figure 20] 19A and 19B are schematic cross-sectional views illustrating an example of operation when adjusting the polarization direction of the ink-jet head shown in FIG. 18. [Figure 21] 19A and 19B are schematic cross-sectional views illustrating another example of operation when adjusting the polarization direction in the ink-jet head shown in FIG. 18. DETAILED DESCRIPTION OF THE INVENTION

[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 Cantilever Type Liquid Jet Head) 2. Modification (Example of a Chevron-Type Liquid Jet Head) 3. Other Modifications

[0011] <1. 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 apparatus according to an embodiment of the present disclosure. The printer 1 is an inkjet printer that records (prints) images, characters, etc. on recording paper P as a recording medium using ink 9, which will be described later. Note that this recording medium is not limited to paper, and may include other recordable materials, such as ceramic and glass.

[0012] As shown in FIG. 1, the printer 1 includes 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. These components are housed in a housing 10 having a predetermined shape. In this embodiment, a circulation-type inkjet head that circulates ink 9 between the ink tank 3 and the inkjet head 4 will be described as an example, as will be described in detail later. Note that in the drawings used in the description of this specification, the scale of each component has been appropriately changed so that each component is large enough to be easily recognized. In addition, in this embodiment, a control method for 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 these transport mechanisms 2a and 2b has a grid roller 21, a pinch roller 22, and a drive mechanism (not shown). This 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 tanks 3 are tanks that contain ink 9. In this example, as shown in FIG. 1, four types of ink tanks 3 are provided, each containing 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] The ink tanks 3Y, 3M, 3C, and 3K have the same configuration except for the color of the ink 9 they contain, and therefore will be collectively referred to as 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 onto recording paper P from a plurality of nozzles (nozzle holes Hn) described below to record (print) images, characters, etc. In this example, as shown in FIG. 1, the inkjet head 4 is provided with four types of heads that individually eject the four colors of ink 9 contained in the ink tanks 3Y, 3M, 3C, and 3K. That is, the inkjet head 4Y ejects yellow ink 9, the inkjet head 4M ejects magenta ink 9, the inkjet head 4C ejects cyan ink 9, and the inkjet head 4K ejects black ink 9. These inkjet heads 4Y, 4M, 4C, and 4K are arranged side by side along the X-axis direction within the housing 10.

[0018] The inkjet heads 4Y, 4M, 4C, and 4K have the same configuration except for the color of ink 9 they use, and therefore will be hereinafter referred to collectively as the inkjet head 4. 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 the ink tank 3 to the inkjet head 4. The ink supply pipe 50 is made of, for example, a flexible hose that is flexible enough 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 Fig. 1, the scanning mechanism 6 has a pair of guide rails 61a, 61b that extend along the Y-axis direction, a carriage 62 that is movably supported on these guide rails 61a, 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, 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. The four types of inkjet heads 4Y, 4M, 4C, and 4K described above are arranged on the carriage 62 along the Y-axis.

[0022] The scanning mechanism 6 and the transport mechanisms 2a and 2b described above constitute a movement mechanism that moves the inkjet head 4 and the recording paper P relatively. The movement mechanism is not limited to this type, and may be, for example, a system in which the inkjet head 4 and the recording medium (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 system").

[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 illustrating an example of the overall configuration of the inkjet head 4. For convenience, a cover plate 43, which will be described later, is omitted from FIG. 2. FIG. 3 is an exploded perspective view illustrating an example of the detailed configuration of the inkjet head 4 illustrated in FIG. 1. FIG. 4 is a schematic diagram illustrating an example of the planar configuration (XY plane configuration) of the actuator plate 42 and other components illustrated in FIG. 3. For convenience, FIG. 4 selectively illustrates the actuator plate 42 of the inkjet head 4. FIG. 5 is a schematic diagram illustrating an example of a cross-sectional configuration (ZX cross-sectional configuration) taken along line VV in FIG. 4, and FIG. 6 is a schematic diagram illustrating an example of a cross-sectional configuration (ZY cross-sectional configuration) taken along line VI-VI in FIG. 4. FIG. 7 is a schematic cross-sectional view (ZX cross-sectional view) of an enlarged portion VII illustrated 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 Figures 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] Here, nozzle plate 41, actuator plate 42, and cover plate 43 correspond to a specific example of an "ejection unit" in the present disclosure, actuator plate 42 corresponds to a specific example of a "piezoelectric substrate" in the present disclosure, and drive unit 49 corresponds to a specific example of a "voltage application unit" in the present disclosure.

[0027] The nozzle plate 41, actuator plate 42, and cover plate 43 are attached to one another 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) that eject 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 predetermined intervals. As shown in FIGS. 3 and 4, the nozzle plate 41 is provided with two nozzle rows (nozzle rows 411, 412) that each extend 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 array 411 has a plurality of nozzle holes H1 arranged in a straight line at predetermined intervals along the X-axis direction. Each of these nozzle holes H1 penetrates the nozzle plate 41 in its thickness direction (Z-axis direction) and communicates with an ejection channel C1e in the actuator plate 42, which will be described later. Specifically, as shown in FIG. 4, each nozzle hole H1 is formed so as to be located at the center of the ejection channel C1e along the Y-axis direction. The nozzle holes H1 are formed at the same pitch along the X-axis direction as the ejection channels C1e along the X-axis direction. From the nozzle holes H1 in the nozzle array 411, ink 9 supplied from the ejection channel C1e is ejected (splashed), as will be described in detail later.

[0030] Similarly, the nozzle array 412 has a plurality of nozzle holes H2 arranged in a straight line at predetermined intervals along the X-axis direction. Each of these nozzle holes H2 also penetrates the nozzle plate 41 in 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 also formed at the same pitch along the X-axis direction as the ejection channels C2e. As will be described in detail later, ink 9 supplied from the ejection channel C2e is also ejected from the nozzle holes H2 in the nozzle array 412.

[0031] Each of these nozzle holes Hn (H1, H2) is a tapered through-hole whose diameter gradually decreases downward (see FIGS. 2, 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 (piezoelectric substrate) made of a piezoelectric material such as PZT (lead zirconate titanate), and is configured to change the volumes of the ejection channels C1e and C2e (described in detail below). The actuator plate 42 is configured of a single piezoelectric substrate (a so-called cantilever type) whose polarization direction dp is set in one direction along the thickness direction (Z-axis direction), as described in detail below (FIG. 12, etc.).

[0033] 3 and 4, two channel rows (channel rows 421 and 422) each extending along the X-axis direction are provided on the actuator plate 42. These channel rows 421 and 422 are arranged 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 (the region where the channel rows 421, 422 are formed) is the ejection region (jetting region) for the ink 9. Meanwhile, both end portions along the X-axis direction of the actuator plate 42 (regions where the channel rows 421, 422 are not formed) are non-ejection regions (non-jetting regions) for the ink 9. These non-ejection regions are located outside the above-mentioned ejection regions along the X-axis direction. Note that both end portions along the Y-axis direction of the actuator plate 42 each constitute a tail portion 420 (see FIG. 4).

[0035] As shown in Figures 3 and 4, the channel row 421 has a plurality of channels C1 extending along the Y-axis direction. These channels C1 are arranged parallel to one another at predetermined intervals 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 forms a concave groove in cross-sectional view.

[0036] Similarly, as shown in FIGS. 3 and 4, the channel array 422 has a plurality of channels C2 extending along the Y-axis direction. These channels C2 are arranged parallel to one another at predetermined intervals along the X-axis direction. As shown in FIG. 3, each channel C2 is also defined by the drive walls Wd and forms a concave groove in cross section. Each drive wall Wd functions as an element (piezoelectric element) for individually pressurizing the inside of each channel C1, C2 (each of the ejection channels C1e, C2e described below).

[0037] 3 to 5, the channel C1 includes ejection channels C1e for ejecting ink 9 (filled with ink 9) and dummy channels C1d that do not eject 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, with the drive walls Wd interposed therebetween. Each of the ejection channels C1e individually communicates with a corresponding one of the nozzle holes H1 in the nozzle plate 41, while each of the dummy channels C1d does not communicate with the corresponding nozzle hole 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 ejection channels C2e for ejecting ink 9 (filled with ink 9) and dummy channels C2d that do not eject ink 9 (not filled with ink 9). In the channel array 422, these ejection channels C2e and dummy channels C2d are alternately arranged along the X-axis direction, with the drive walls Wd interposed therebetween. Each of the ejection channels C2e individually communicates with a corresponding one of the nozzle holes H2 in the nozzle plate 41, while each of the dummy channels C2d does not communicate with the corresponding nozzle hole 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 channel C1 are arranged alternately with respect to the ejection channels C2e and dummy channels C2d in channel C2. Therefore, in the inkjet head 4, the ejection channels C1e in channel C1 and the ejection channels C2e in channel C2 are arranged in a staggered pattern. Note that, as shown in FIG. 3, shallow grooves Dd that communicate with the outer ends of the dummy channels C1d and C2d along the Y-axis direction are formed in the actuator plate 42 in portions corresponding to the dummy channels C1d and C2d.

[0041] 3 and 6, each ejection channel C1e has an arc-shaped side surface in which the cross-sectional area of ​​the 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 ​​the 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 cutting using a dicer, for example.

[0042] As shown in FIGS. 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. As shown in FIGS. 3, 5, and 7, the driving electrodes Ed (common electrode Edc and individual electrode Eda) are formed only to a midpoint 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] 3, a flexible printed circuit board 493 is mounted on the tail portion 420 to electrically connect the drive electrodes Ed and the drive unit 49. A wiring pattern (not shown) formed on the flexible printed circuit board 493 is electrically connected to the common terminal and the individual terminals. This allows a drive voltage Vd (drive signal Sd) (to be described later) and the like to be applied to each drive electrode Ed from the drive unit 49 (to be described later) 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 and C2 (the channel rows 421 and 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 and Rin2 and a pair of recovery-side common flow paths Rout1 and Rout2 are formed in the cover plate 43. Also, as shown in Fig. 6, the cover plate 43 is formed with wall portions W1 and W2.

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

[0048] As shown in Fig. 3, the supply-side common flow channels Rin1 and Rin2 and the recovery-side common flow channels Rout1 and 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 channel Rin1 and the recovery-side common flow channel Rout1 are each formed in an area of ​​the actuator plate 42 corresponding to the channel row 421 (plurality of channels C1) (see Figs. 3 and 6). On the other hand, the supply-side common flow channel Rin2 and the recovery-side common flow channel Rout2 are each formed in an area of ​​the actuator plate 42 corresponding to the channel row 422 (plurality of channels C2) (see Figs. 3 and 6).

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

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

[0051] 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). The supply slit Sin1 and the recovery slit Sout1 each serve as a through-hole through which ink 9 flows between the ejection channel C1e and the supply-side common flow channel Rin1. Specifically, the supply-side common flow channel Rin1 supplies ink 9 to the ejection channel C1e via the supply slit Sin1, and the recovery-side common flow channel Rout1 recovers ink 9 from the ejection channel C1e via the recovery slit Sout1 (see the dashed arrows in FIG. 6). On the other hand, neither the supply-side common flow channel Rin1 nor the recovery-side common flow channel Rout1 are connected to each dummy channel C1d. Specifically, each dummy channel C1d is blocked by the bottoms of the supply-side common flow channel Rin1 and the recovery-side common flow channel Rout1.

[0052] Similarly, the supply-side common flow path Rin2 and the recovery-side common flow path Rout2 are connected to each ejection channel C2e via a supply slit Sin2 and a recovery slit Sout2, respectively (see FIG. 3). The supply slit Sin2 and the recovery slit Sout2 each serve as a through-hole through which ink 9 flows between the ejection channel C2e and the supply-side common flow path Rin2. Specifically, the supply-side common flow path Rin2 supplies ink 9 to the ejection channel C2e via the supply slit Sin2, and the recovery-side common flow path Rout2 recovers ink 9 from the ejection channel C2e via the recovery slit Sout2. Meanwhile, neither the supply-side common flow path Rin2 nor the recovery-side common flow path Rout2 is connected to each dummy channel C2d (see FIG. 6). Specifically, each dummy channel C2d is blocked by the bottoms of the supply-side common flow path Rin2 and the recovery-side common flow path Rout2 (see FIG. 6).

[0053] (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). In this case, 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).

[0054] Furthermore, the drive unit 49 drives the actuator plate 42 to eject the ink 9 filled in the ejection channels C1e and C2e from the nozzle holes Hn (H1 and H2) (see FIGS. 2, 5 to 7). Specifically, the drive unit 49 applies the drive voltage Vd (drive signal Sd) to the actuator plate 42 to expand and contract the ejection channels C1e and C2e, thereby ejecting the ink 9 from each nozzle hole Hn (performing an ejection operation).

[0055] As will be described in detail below, the drive unit 49 also functions as a voltage application unit that adjusts the polarization direction within the actuator plate 42. Specifically, the drive unit 49 adjusts the polarization direction by applying a voltage (a voltage waveform Wv, which will be described later) to the actuator plate 42 for each of the ejection channels C1e and C2e. As a result, the ejection characteristics of the ink 9 in the inkjet head 4 are adjusted (the variation in the ejection characteristics of the ink 9 among the plurality of nozzle holes Hn is suppressed), as will be described in detail below.

[0056] [C. Detailed Configuration of Drive Voltage Vd, Drive Signal Sd, and Voltage Waveform Wv] Next, detailed configuration examples of the drive voltage Vd, drive signal Sd, and voltage waveform Wv will be described with reference to FIGS.

[0057] 8 is a schematic diagram showing an example of a supply path for each potential supplied from the drive unit 49 to the drive electrodes Ed (individual electrodes Eda and common electrode Edc). Specifically, FIG. 8 shows an example of a supply path for the potential supplied to the individual electrode Eda (individual potential Vda) and the potential supplied to the common electrode Edc (common potential Vdc) for channel C1. Although not shown in FIG. 8 for convenience, the same applies to an example of a supply path for channel C2 (example of a supply path for the individual potential Vda and common potential Vdc).

[0058] Fig. 9 is a timing diagram showing an example of the waveform of the drive signal Sd during the printing operation. Fig. 10 (Fig. 10(A) and Fig. 10(B)) is a timing diagram showing an example of the voltage waveform Wv applied during the polarization direction adjustment.

[0059] 9 and 10, the vertical axis represents the driving voltage Vd or the applied voltage Vp (both of which correspond to the potential difference between the individual potential Vda and the common potential Vdc described above: Vd, Vp = Vda - Vdc), and the horizontal axis represents time t. The magnitudes (voltage values) of the driving voltage Vd and the applied voltage Vp correspond to the volumes of the ejection channels C1e and C2e described above. When the driving voltage Vd is positive (+) or negative (-), it indicates that the volume is expanded or contracted relative to the reference value, respectively (see FIG. 9).

[0060] 9 and 10, the common potential Vdc is set to a predetermined positive potential (Vdc>0), thereby setting the drive voltage Vd and the applied voltage Vp (the potential difference between the individual potential Vda and the common potential Vdc) to a negative value (Vd<0). However, this is not limiting. 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), thereby directly setting the drive voltage Vd and the applied voltage Vp to a negative value (Vd<0). Even in such a case, it is possible to perform the same control (pressure fluctuation in the actuator plate 42) as in the example shown in FIGS. 9 and 10.

[0061] 9, the drive signal Sd is a signal having multiple pulses (pulses p1 and p2) within one cycle (a drive cycle Td described below) (a signal to which the so-called "multi-pulse method" is applied). Pulse p1 is a pulse (expansion pulse) for expanding the volumes of the ejection channels C1e and C2e, and pulse p2 is a pulse (contraction pulse) for contracting the volumes of the ejection channels C1e and C2e.

[0062] Here, the above-mentioned "one cycle (= drive cycle Td)" refers to the time interval required to form one pixel (dot) on the recording paper P (recording medium). The drive frequency fd of the drive signal Sd 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).

[0063] 10(A) and 10(B), the voltage waveform Wv applied during the above-described polarization direction adjustment is, for example, a rectangular wave having a voltage value ΔVp (amplitude) and a voltage application time Tv. In detail, the voltage waveform Wv shown in Fig. 10(A) has a positive polarity (positive voltage value ΔVp), while the voltage waveform Wv shown in Fig. 10(B) has a negative polarity (negative voltage value ΔVp).

[0064] [Operation, Actions and Effects] (A. Basic operation of Printer 1) In this printer 1, the operation of recording (printing) images, characters, etc. onto 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 assumed to be fully filled with ink 9 of the corresponding color (four colors). The ink 9 in the ink tanks 3 is also filled into the inkjet head 4 via the ink supply pipe 50.

[0065] When the printer 1 is operated in this initial state, the grid rollers 21 in the transport mechanisms 2a and 2b rotate, transporting the recording paper P 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, thereby operating the endless belt 632. As a result, the carriage 62 moves back and forth along the width direction (Y-axis direction) of the recording paper P while being 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. on the recording paper P.

[0066] (B. Detailed Operation of Inkjet Head 4) Next, detailed operations (operations by ejection driving) of the inkjet head 4 will be described.

[0067] 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, causing the ink 9 filled in the ejection channels C1e and C2e to be ejected from the nozzle holes Hn.

[0068] During this ejection drive, 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 dummy channels C1d and C2d adjacent to the ejection channels C1e and C2e.

[0069] As described above, the polarization direction dp of the actuator plate 42 is set to one direction, and the drive electrode Ed is formed only up to the middle 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 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 da shown in FIG. 7).

[0070] In this way, the volume of the ejection channels C1e and C2e increases due to the bending deformation caused by the piezoelectric thickness shear effect at the pair of drive walls Wd. As the volume of the ejection channels C1e and C2e increases, the ink 9 stored in the supply-side common flow paths Rin1 and Rin2 is guided into the ejection channels C1e and C2e via the supply slits Sin1 and Sin2 (see, for example, the dashed arrows in Figure 6).

[0071] Next, the ink 9 guided into the ejection channels C1e and C2e in this manner becomes a pressure wave that propagates inside the ejection channels C1e and C2e. When this pressure wave reaches the nozzle hole Hn of the nozzle plate 41 (or at a timing close to this), the drive voltage Vd applied to the drive electrode Ed becomes 0 (zero) V. This causes the drive wall Wd to return to its original state from the bent and deformed state described above, and the volume of the ejection channels C1e and C2e, which had temporarily increased, returns to its original volume (see, for example, the contraction direction db shown in FIG. 7).

[0072] In this way, as the volumes of the ejection channels C1e, C2e return to their original state, the pressure inside the ejection channels C1e, C2e increases, and the ink 9 inside 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 inkjet head 4 performs a jetting 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.

[0073] A portion of the ink 9 filled in the ejection channels C1e and C2e is recovered into the recovery-side common flow paths Rout1 and Rout2 through the recovery slits Sout1 and Sout2 (see, for example, the dashed arrows in FIG. 6). The ink 9 recovered into these recovery-side common flow paths Rout1 and Rout2 is returned from the inkjet head 4 to the ink tank 3 through the ink supply pipe 50. In this way, the ink 9 is circulated.

[0074] (C. Comparative Examples) In recent years, conventional inkjet heads have been increasingly applied to fields requiring high resolution and precision, such as semiconductor manufacturing equipment and electronic circuit board manufacturing, and improvements in print quality are being demanded. To improve print quality in inkjet heads, it is necessary, for example, to reduce the variation (non-uniformity) in ink ejection characteristics (ejection speed, etc.) among multiple nozzle holes and make them as uniform as possible. Achieving uniformity in such ink ejection characteristics requires, for example, high-definition, high-precision material processing and assembly technologies in the inkjet head manufacturing process.

[0075] However, this manufacturing process requires high costs and strict quality control, and there are naturally limits to what can be achieved by pursuing processing technology alone. Furthermore, because ejection inspection is carried out at a later stage in the inkjet head manufacturing process, any defective products will incur significant disposal costs.

[0076] Therefore, in the inkjet head 104 of the comparative example shown in Fig. 11, the magnitude of polarization in the piezoelectric body 102 is adjusted to suppress variations in the ejection characteristics (ejection speed, etc.) of the ink 9 among the multiple nozzle holes Hn. Fig. 11 is a schematic cross-sectional view (ZX cross-sectional view) of an example of the general configuration of the inkjet head 104 of the comparative example. Fig. 11 also shows the polarization state (positive polarization state: "+" and negative polarization state: "-") in the piezoelectric body 102, the polarization direction dp in the piezoelectric body 102, and the voltage application direction dv for each ejection channel Ce.

[0077] The inkjet head 104 of this comparative example differs from the inkjet head 4 of this embodiment (see FIGS. 5 to 7, etc.) in that it has the following configuration. Specifically, as shown in FIG. 11, in this inkjet head 104, a pair of drive electrodes Ed1 and Ed2 are arranged on either side of a piezoelectric body 102 provided on a cover plate 43, rather than on a member 101 between the ejection channels Ce. Also, in this inkjet head 104, the polarization direction dp in the piezoelectric body 102 and the voltage application direction dv for each ejection channel Ce are both the direction between these drive electrodes Ed1 and Ed2 (Z-axis direction) (see FIG. 11).

[0078] In this comparative example, the magnitude of polarization in the piezoelectric body 102 is adjusted by changing the value of the applied voltage in the voltage application direction dv in accordance with the measured value of the electrostatic capacitance of the piezoelectric body 102. However, in the inkjet head 104 of this comparative example, as described above, the voltage application direction dv for each ejection channel Ce and the polarization direction dp in the piezoelectric body 102 are the same direction. Therefore, in this comparative example, since only the magnitude of polarization in the piezoelectric body 102 is adjusted, it is difficult to fine-tune the polarization state, and it can be said that it is also difficult to suppress variations in the ejection characteristics of the ink 9 among the multiple nozzle holes Hn.

[0079] For these reasons, it is desirable to propose a method that makes it easy to suppress variations in ink ejection characteristics between multiple nozzle holes and also makes it easy to improve the print quality of inkjet heads.

[0080] (D. Adjustment of polarization direction in this embodiment) Therefore, in the inkjet head 4 of this embodiment, the ejection characteristics of the ink 9 are adjusted by adjusting the polarization direction dp within the actuator plate 42. Specifically, the driving unit 49 applies the voltage waveform Wv described above to the actuator plate 42 for each of the ejection channels C1e and C2e, thereby adjusting the polarization direction dp. As will be described in detail later, this allows the ejection characteristics of the ink 9 in the inkjet head 4 to be adjusted (reducing variations in the ejection characteristics of the ink 9 among the multiple nozzle holes Hn).

[0081] Fig. 12 is a schematic cross-sectional view (ZX cross-sectional view) showing an example of operation during printing in the inkjet head 4 of this embodiment. Similar to Fig. 11, Fig. 12 shows the polarization state (positive polarization state: "+", negative polarization state: "-") in the actuator plate 42, as well as the polarization direction dp in the actuator plate 42 and the voltage application direction dv1 for each of the ejection channels Ce1 and Ce2.

[0082] First, as described above, the inkjet head 4 of this embodiment ejects the ink 9 using the shear mode. Therefore, during the printing operation shown in FIG. 12 and during polarization direction adjustment (see FIGS. 14 and 15), which will be described later, the voltage application direction for each of the ejection channels Ce1 and Ce2 is configured to be different from the polarization direction dp in the initial state within the actuator plate 42. Specifically, in the example of FIG. 12 (and FIGS. 14 and 15, which will be described later), the voltage application direction for each of the ejection channels Ce1 and Ce2 is configured to be perpendicular to the polarization direction dp in the initial state within the actuator plate 42.

[0083] Specifically, during the printing operation shown in FIG. 12, for example, as shown in FIG. 12A, the voltage application direction dv1 (X-axis direction) for each ejection channel Ce1, Ce2 and the polarization direction dp (Z-axis direction) in the initial state within the actuator plate 42 are perpendicular to each other. As a result, in the inkjet head 4, the drive wall Wd of the actuator plate 42 is displaced, for example, as indicated by the solid arrow in FIG. 12B. As described in detail below, this embodiment, unlike the comparative example, allows adjustment of the slope (polarization component) from the initial state in the polarization direction dp, thereby enabling fine adjustment of the polarization state. Furthermore, in this embodiment, as described in detail below, this adjustment of the slope from the initial state in the polarization direction dp is achieved by performing a predetermined correction process on the voltage waveform Wv described above.

[0084] FIG. 13 is a flow chart illustrating an example of a process for adjusting the polarization direction (adjusting the polarization direction dp) according to this embodiment. FIGS. 14 and 15 are schematic cross-sectional views (ZX cross-sectional views) illustrating an example of the operation during polarization direction adjustment shown in FIG. 13, with (A) illustrating the initial state and (B) illustrating the state after the polarization direction dp has been adjusted. FIG. 16 is a characteristic diagram illustrating an example of the relationship between the nozzle positions (of the multiple nozzle holes Hn) and the ejection characteristics of the ink 9 before the polarization direction dp is adjusted as shown in FIG. 13. Meanwhile, FIG. 17 is a characteristic diagram illustrating an example of the relationship between the nozzle positions and the ejection characteristics of the ink 9 after the polarization direction dp is adjusted as shown in FIG. 13.

[0085] 13, first, an initial characteristic value Vci of the ejection characteristics of the ink 9 is measured in advance for each of the ejection channels C1e and C2e in the inkjet head 4 (step S11). Note that such ejection characteristics of the ink 9 include, for example, at least one of the ejection speed Ve of the ink 9, the droplet volume DV of the ink 9, and the concentration distribution Dc of the ink 9 on the recording paper P (recording medium).

[0086] Next, the drive unit 49 (voltage application unit) derives a correction amount ΔVc for each of the ejection channels C1e and C2e based on the comparison result between the initial characteristic value Vci and the target characteristic value Vct of the ejection characteristics of the ink 9 (step S12). Specifically, the drive unit 49 derives the correction amount ΔVc for the correction process on the voltage waveform Wv described above so that the ejection characteristics of the ink 9 become the target characteristic value Vct. Note that the correction target for the voltage waveform Wv in such a correction process includes, for example, at least one of the voltage application time Tv, voltage value ΔVp (DC voltage value), polarity of the applied voltage Vp, and duty ratio.

[0087] Here, for example, a predetermined upper limit value ΔVcth may be set for the correction amount ΔVc for each of the ejection channels C1e and C2e in this correction process (ΔVc≦ΔVcth). Note that this upper limit value ΔVcth is determined using, for example, the voltage application time Tv and the magnitude of the voltage value ΔVp that can be set as the voltage waveform Wv, a predicted value of the magnitude of the drive voltage Vc, and the like.

[0088] Furthermore, during such correction processing, the driving unit 49 may derive the correction amount ΔVc for each of the ejection channels C1e and C2e by using, for example, a moving average related to the arrangement distribution of the ejection channels C1e and C2e in the ejection characteristics of the ink 9. When the correction amount ΔVc is derived using such a moving average, it is possible to suppress reproducibility errors (noise) in the measurement system while equalizing continuous distortion in the ejection characteristics of the ink 9. Note that when deriving such a moving average, for example, an average may be derived within a range of 10 nozzles (10 nozzle holes Hn), and the moving average may also be derived between, for example, multiple nozzle rows 411 and 412 or multiple inkjet heads 4.

[0089] Next, the drive unit 49 determines a voltage waveform Wv for each of the ejection channels C1e and C2e based on the correction amount ΔVc for each of the ejection channels C1e and C2e and the rate of change in the characteristic value of the ink 9 with respect to the application of voltage to the ejection channels C1e and C2e (characteristic value change rate Rc) (step S13).The drive unit 49 then applies a voltage to the actuator plate 42 for each of the ejection channels C1e and C2e based on the determined voltage waveform Wv, thereby adjusting the polarization direction dp for each of the ejection channels C1e and C2e (step S14).Specifically, as described above, the drive unit 49 adjusts the tilt of the polarization direction dp in the actuator plate 42 from the initial state for each of the ejection channels C1e and C2e, thereby suppressing variations in the ejection characteristics of the ink 9 among the multiple nozzle holes Hn.

[0090] 14A and 14B, if the voltage application direction dv2 during the adjustment of the polarization direction dp is set to the same direction as the voltage application direction dv1 during the printing operation (see FIG. 12A), the following occurs: In this case, the tilt of the polarization direction dp from the initial state is adjusted, and when the drive wall Wd is displaced as described above, the amount of deformation of the drive wall Wd becomes relatively small, and as a result, the ejection characteristics of the ink 9 (such as the ejection velocity Ve) become relatively small.

[0091] 15(A) and 15(B), if the voltage application direction dv2 during the adjustment of the polarization direction dp is set opposite to the voltage application direction dv1 during the printing operation (see FIG. 12(A)), the following occurs: In this case, the tilt of the polarization direction dp from the initial state is adjusted, and when the drive wall Wd is displaced as described above, the amount of deformation of the drive wall Wd becomes relatively large, and as a result, the ejection characteristics of the ink 9 (ejection velocity Ve, etc.) become relatively large.

[0092] In this manner, in this embodiment, as shown in Figures 16 and 17, for example, the variation in the ejection characteristics (ejection speed Ve, etc.) of the ink 9 among the multiple nozzle holes Hn is suppressed before and after the adjustment of the polarization direction dp. Specifically, first, in the example of the relationship between the nozzle position and the ejection characteristics of the ink 9 before the adjustment of the polarization direction dp shown in Figure 16, the variation (non-uniformity) in the ejection characteristics depending on the nozzle position is large. In contrast, in the example of the relationship between the nozzle position and the ejection characteristics of the ink 9 after the adjustment of the polarization direction dp shown in Figure 17, the variation (non-uniformity) in the ejection characteristics depending on the nozzle position is smaller (suppressed) than in the case before the adjustment shown in Figure 16.

[0093] Note that, when adjusting the polarization direction dp in this manner, the above-described correction process may be performed, for example, to match the ejection characteristics of the nozzle holes Hn (e.g., in a nozzle row) with the ejection characteristics (e.g., ejection velocity Ve) of the nozzle hole Hn with the smallest ejection characteristics. This is because such correction process facilitates control of the ejection characteristics. Furthermore, as shown by the dashed arrows in FIG. 17, a further correction process may be performed to uniformly inflate the ejection characteristics of each nozzle hole Hn, thereby matching the average value of the ejection characteristics across the nozzle holes Hn with the adjustment of the polarization direction dp. This maintains the average value of the ejection characteristics across the nozzle holes Hn before and after the adjustment of the polarization direction dp.

[0094] Here, when applying the above-described voltage waveform Wv (step S14), for example, the temperature of the actuator plate 42 may be set to a higher temperature (for example, about 30°C to 80°C) than room temperature (for example, about 20°C to 30°C). This is because the processing time required for adjusting the polarization direction dp is shortened. Note that, for example, by superimposing a predetermined rectangular waveform on the voltage waveform Wv, the adjustment of the polarization direction dp and the heating of the actuator plate 42 may be performed simultaneously (in parallel).

[0095] Next, the drive unit 49 determines whether the variation in the ejection characteristics of the ink 9 described above is within a predetermined target range (step S15). If it is determined that the variation in the ejection characteristics is not within the predetermined target range (step S15: N), the process returns to step S11. On the other hand, if it is determined that the variation in the ejection characteristics is within the predetermined target range (step S15: Y), an aging process is then performed (step S16). This aging process is a process for stabilizing the polarization state within the actuator plate 42, and is a process in which the actuator plate 42 is stored under constant temperature conditions (without voltage application). However, for example, such an aging process may not be performed.

[0096] This completes the processing example for adjusting the polarization direction shown in FIG.

[0097] (E. Actions and Effects) In this manner, in this embodiment, when the voltage waveform Wv is applied to the actuator plate 42 (piezoelectric substrate) of the inkjet head 4 for each of the ejection channels C1e and C2e, the polarization direction is adjusted as follows. That is, in this embodiment, a predetermined correction process is performed on the voltage waveform Wv, and unlike the comparative example described above, the tilt from the initial state in the polarization direction dp in the actuator plate 42 is adjusted individually for each of the ejection channels C1e and C2e.

[0098] As a result, in this embodiment, the suppression of variations in the ejection characteristics of the ink 9 among the multiple nozzle holes Hn is achieved simply by correcting the voltage waveform Wv. In other words, the suppression of variations in the ejection characteristics of the ink 9 described above is achieved without requiring any changes to the structure of the inkjet head 4 itself (without adding a new electric circuit or the like within the inkjet head 4 or receiving control from a new control device or the like provided outside the inkjet head 4). Therefore, in this embodiment, it is possible to easily achieve an improvement in the print image quality using the inkjet head 4.

[0099] It is also possible to suppress variations in the ejection characteristics of the ink 9 between the channel rows 421 and 422 in the inkjet head 4. Furthermore, for example, if a plurality of inkjet heads 4 are provided in the printer 1, it is also possible to suppress variations in the ejection characteristics of the ink 9 between the plurality of inkjet heads 4.

[0100] Furthermore, in this embodiment, the voltage waveform Wc for each of the ejection channels C1e and C2e is determined based on the correction amount ΔVc for each of the ejection channels C1e and C2e and the characteristic value change rate Rc described above, resulting in the following: That is, the characteristic value change rate Rc obtained by pre-measurement is used to determine the voltage waveform Wc for obtaining the desired ejection characteristics, improving the accuracy of polarization direction adjustment and enabling the process to be stabilized.

[0101] Furthermore, in this embodiment, after the above-described adjustment of the polarization direction dp, an aging process is further performed to stabilize the polarization state within the actuator plate 42, resulting in the following: Immediately after voltage application, the polarization state is unstable, and a rebound in the ejection characteristics occurs over a long period of time. However, by performing such an aging process, it becomes possible to stabilize the polarization state. The voltage waveform Wv may be determined taking into account the amount of such a rebound in the ejection characteristics. In this case, it becomes possible to improve the accuracy of setting the ejection characteristics.

[0102] Additionally, in this embodiment, when individually adjusting the gradient of the polarization direction dp, the application direction of the voltage waveform Wv (voltage application direction dv2) for each of the ejection channels C1e and C2e is made different from the polarization direction dp of the initial state within the actuator plate 42. This allows for fine adjustment of the polarization state, unlike the comparative example described above. Furthermore, for example, as described above, if the voltage application direction dv2 is made perpendicular to the polarization direction dp of the initial state within the actuator plate 42, it becomes possible to easily adjust the polarization state in accordance with the actual deformation mode of the drive wall Wd.

[0103] <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.

[0104] (composition) Fig. 18 is a schematic cross-sectional view (ZX cross-sectional view) illustrating an example of the overall configuration of an inkjet head 4a according to a modified example. Fig. 19 is a schematic cross-sectional view (ZX cross-sectional view) illustrating an example of operation during printing in the inkjet head 4a shown in Fig. 18. Figs. 20 and 21 are each a schematic cross-sectional view (ZX cross-sectional view) illustrating an example of operation during polarization direction adjustment in the inkjet head 4a shown in Fig. 18.

[0105] The inkjet head 4a of this modified example differs from the inkjet head 4 (cantilever type configuration example) of the embodiment in that it is a chevron type configuration example, as will be described below. Specifically, as described above, the actuator plate 42 of the inkjet head 4 is configured using a single piezoelectric substrate. In contrast, as shown in FIG. 18, the actuator plate 42 of the inkjet head 4a is configured using multiple (two) piezoelectric substrates 42a, 42b stacked along the thickness direction (Z-axis direction). Furthermore, in this inkjet head 4a, the common electrode Edc and the individual electrodes Eda are each formed on the inner surface of the drive wall Wd, extending downward in the depth direction (Z-axis direction), as shown in FIG. 18, for example.

[0106] Furthermore, in this inkjet head 4a, the polarization direction dpa in the piezoelectric substrate 42a and the polarization direction dpb in the piezoelectric substrate 42b are set to be opposite to each other (see FIG. 18). On the other hand, the voltage application directions to these piezoelectric substrates 42a and 42b (voltage application direction dv1 during printing operation shown in FIG. 18 and voltage application direction dv2 during polarization direction adjustment shown in FIGS. 20 and 21, which will be described later) are set to be the same.

[0107] The inkjet head 4a corresponds to a specific example of a "liquid jet head" in the present disclosure, and a printer equipped with this inkjet head 4a corresponds to a specific example of a "liquid jet recording apparatus" in the present disclosure.

[0108] In the inkjet head 4a of this modified example, as in the inkjet head 4 of the embodiment, the printing operation shown in FIGS. 18 and 19 is as follows. That is, the voltage application direction dv1 (X-axis direction) for each ejection channel Ce1, Ce2 and the initial polarization directions dpa, dpb (Z-axis direction) within the actuator plate 42 (piezoelectric substrates 42a, 42b) are perpendicular to each other. As a result, in the inkjet head 4a, the drive walls Wd (drive walls Wda, Wdb corresponding to the piezoelectric substrates 42a, 42b) of the actuator plate 42 are displaced, as indicated by the solid arrows in FIG. 19. As a result, the amount of deformation of the drive walls Wd in the inkjet head 4a is greater than the amount of deformation of the drive walls Wd in the inkjet head 4.

[0109] In addition, in the inkjet head 4a of this modified example, the polarization directions dpa and dpb are adjusted by carrying out correction processing and the like in the same manner as in the inkjet head 4 of the embodiment.

[0110] Specifically, as shown in Figure 20, if the voltage application direction dv2 during the polarization direction adjustment is set to the same direction as the voltage application direction dv1 during the printing operation (see Figure 18), the following occurs: In this case, the inclinations of the polarization directions dpa and dpb from the initial state are adjusted, and when the drive wall Wd (Wda, Wdb) is displaced as described above, the amount of deformation of the drive wall Wd becomes relatively small, and as a result, the ejection characteristics (ejection velocity Ve, etc.) of the ink 9 become relatively small.

[0111] On the other hand, as shown in Figure 21, if the voltage application direction dv2 during the polarization direction adjustment is set to the opposite direction to the voltage application direction dv1 during the printing operation (see Figure 18), the following occurs: In this case, the tilt from the initial state in the polarization directions dpa and dpb is adjusted, and when the driving wall Wd (Wda, Wdb) is displaced as described above, the amount of deformation of the driving wall Wd becomes relatively large, and as a result, the ejection characteristics (ejection velocity Ve, etc.) of the ink 9 become relatively large.

[0112] (Actions and Effects) Even in this modified configuration, it is possible to obtain the same effects as in the embodiment by basically operating in the same manner, i.e., it is possible to easily achieve an improvement in the print quality of the inkjet head 4a.

[0113] <3. Other Modifications> The present disclosure has been described above by giving embodiments and modifications, but the present disclosure is not limited to these embodiments and can be modified in various ways.

[0114] For example, in the above embodiments, specific configuration examples (shape, arrangement, number, etc.) of each component in the printer and inkjet head are given and described, but they are not limited to those described in the above embodiments, etc., and other shapes, arrangements, numbers, etc. are also possible. Furthermore, the values, ranges, magnitude relationships, etc. of the various parameters described in the above embodiments, etc. are not limited to those described in the above embodiments, etc., and other values, ranges, magnitude relationships, etc. are also possible.

[0115] Specifically, for example, in the above-described embodiment, specific examples of the waveforms of the drive signal Sd and the voltage waveform Wv are given and explained, but they are not limited to those explained in the above-described embodiment.

[0116] Furthermore, various types of inkjet head structures can be applied. For example, in the above-described embodiments, a so-called side-chute type inkjet head that ejects ink 9 from the center of the actuator plate in the direction in which each ejection channel extends has been described as an example. However, the present invention is not limited to this example, and may also be, for example, a so-called edge-chute type inkjet head that ejects ink 9 along the direction in which each ejection channel extends.

[0117] 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.

[0118] In addition, in the above-mentioned embodiments, etc., specific examples of processing examples for adjusting the polarization direction have been described, but the processing examples are not limited to those given in the above-mentioned embodiments, etc., and other processing examples may be used. Furthermore, for example, two or more of the processing examples given in the above-mentioned embodiments, etc. may be used in appropriate combination.

[0119] 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, or may be installed in the computer from a network or a recording medium.

[0120] Furthermore, in the above-described 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 devices other than inkjet printers. In other words, the "liquid jet head" (inkjet head) of the present disclosure may be applied to devices other than inkjet printers. Specifically, the "liquid jet head" of the present disclosure may be applied to devices such as facsimiles and on-demand printers, for example.

[0121] Additionally, the various examples described above may be applied in any combination.

[0122] The effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0123] The present disclosure can also be configured as follows. (1) A method for adjusting ejection characteristics of a liquid in a liquid ejection head including an ejection unit having a plurality of nozzles that eject a liquid, and a piezoelectric substrate including a plurality of pressure chambers that individually communicate with the plurality of nozzles and are each filled with the liquid, the method comprising: When a voltage waveform is applied to the piezoelectric substrate for each pressure chamber, By performing a predetermined correction process on the voltage waveform, the tilt of the polarization direction in the piezoelectric substrate from the initial state is adjusted individually for each pressure chamber. A method for adjusting ejection characteristics of a liquid ejection head. (2) During the correction process, Based on a comparison result between an initial characteristic value and a target characteristic value of the liquid ejection characteristics, Derive a correction amount for each pressure chamber. The method for adjusting the ejection characteristics of the liquid jet head according to (1) above. (3) The voltage waveform for each pressure chamber is determined based on the correction amount for each pressure chamber and the rate of change in the characteristic value of the liquid with respect to the application of a voltage to the pressure chamber. The method for adjusting the ejection characteristics of the liquid jet head according to (2) above. (4) The tilt in the polarization direction is adjusted individually for each pressure chamber, The variation in the ejection characteristics of the liquid among the plurality of nozzles is suppressed. The method for adjusting the ejection characteristics of a liquid jet head according to any one of (1) to (3) above. (5) After the inclination in the polarization direction is adjusted individually for each pressure chamber, An aging process is further performed to stabilize the polarization state within the piezoelectric substrate. The method for adjusting the ejection characteristics of a liquid jet head according to any one of (1) to (4) above. (6) When the voltage waveform is applied to the piezoelectric substrate, the piezoelectric substrate is set to a temperature higher than room temperature. The method for adjusting the ejection characteristics of a liquid jet head according to any one of (1) to (5) above. (7) During the correction process, a moving average relating to the arrangement distribution of the pressure chambers in the ejection characteristics of the liquid is used to derive a correction amount for each of the pressure chambers. The method for adjusting the ejection characteristics of a liquid jet head according to any one of (1) to (6) above. (8) A predetermined upper limit value is set for the correction amount for each pressure chamber in the correction process. The method for adjusting the ejection characteristics of a liquid jet head according to any one of (1) to (7) above. (9) The ejection characteristics include at least one of the ejection speed of the liquid, the droplet volume of the liquid, and the concentration distribution of the liquid on the recording medium. The method for adjusting the ejection characteristics of a liquid jet head according to any one of (1) to (8) above. (10) The voltage waveform to be corrected in the correction process includes at least one of a voltage application time, a voltage value, and a voltage polarity. The method for adjusting the ejection characteristics of a liquid jet head according to any one of (1) to (9) above. (11) When the inclination in the polarization direction is individually adjusted, the direction of application of the voltage waveform in each pressure chamber is made different from the polarization direction in the initial state within the piezoelectric substrate. The method for adjusting the ejection characteristics of a liquid jet head according to any one of (1) to (10) above. (12) When the inclination in the polarization direction is individually adjusted, the direction of application of the voltage waveform in each pressure chamber is made perpendicular to the polarization direction in the initial state within the piezoelectric substrate. The method for adjusting the ejection characteristics of a liquid jet head according to (11) above. (13) an ejection unit having a plurality of nozzles for ejecting liquid and a piezoelectric substrate including a plurality of pressure chambers that are individually connected to the plurality of nozzles and are filled with the liquid; a voltage application unit that applies a voltage waveform to the piezoelectric substrate for each pressure chamber; Equipped with The voltage application unit By performing a predetermined correction process on the voltage waveform, the tilt of the polarization direction in the piezoelectric substrate from the initial state is adjusted individually for each pressure chamber. Liquid injection head. (14) A liquid jet head according to (13) above is provided. Liquid jet recording device. [Explanation of symbols]

[0124] 1...printer, 10...casing, 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 array, 42...actuator plate, 42a, 42b...piezoelectric substrate, 420...tail, 421, 422...channel array, 43...cover plate, 49...drive section (voltage application section), 493...flexible printed circuit board, 50...ink supply pipe, 6...scanning mechanism, 61a, 61b...guide rail, 62...carriage, 63...driving mechanism, 631a, 631b...pulley, 632...endless belt, 633...driving motor, 9...ink, P...recording paper, d...conveying direction, Hn, H1, H2...nozzle hole, Dd...shallow groove section, Rin1, Rin2...supply side common flow path, Rout1, R2...recovery side common flow path , Sin1, Sin2... supply slit, Sout1, Sout2... recovery slit, W1, W2... wall, Sd... drive signal, Vd... drive voltage, Vda... individual potential (active potential), Vdc... common potential (common potential), Vp... applied voltage, ΔVp... voltage value, Wv... voltage waveform, Vci... initial characteristic value, Vct... target characteristic value, ΔVc... correction amount, ΔVcth... upper limit value, Rc... characteristic value change rate, Ve... discharge speed, DV... droplet volume, Dc ...concentration distribution, C1, C2...channel, C1e, C2e...ejection channel, C1d, C2d...dummy channel (non-ejection channel), Wd, Wda, Wdb...driving wall, Ed...driving electrode, Eda...individual electrode (active electrode), Edc...common electrode (common electrode), da...expansion direction, db...contraction direction, dp, dpa, dpb...polarization direction, dv1, dv2...voltage application direction, p1, p2...pulse, t...time, Tv...voltage application time.

Claims

1. A method for adjusting ejection characteristics of a liquid in a liquid ejection head including an ejection unit having a plurality of nozzles that eject a liquid, and a piezoelectric substrate including a plurality of pressure chambers that individually communicate with the plurality of nozzles and are each filled with the liquid, the method comprising: When applying a voltage waveform for adjusting characteristics to the piezoelectric substrate for each pressure chamber, By performing a predetermined correction process on the voltage waveform, the tilt of the polarization direction itself in the piezoelectric substrate from the initial state is individually adjusted in advance for each pressure chamber before the ejection operation of deforming the pressure chamber and ejecting the liquid from the nozzle. A method for adjusting ejection characteristics of a liquid ejection head.

2. During the correction process, Based on a comparison result between an initial characteristic value and a target characteristic value of the liquid ejection characteristics, Derive a correction amount for each pressure chamber. The method for adjusting the ejection characteristics of a liquid jet head according to claim 1 .

3. The voltage waveform for each pressure chamber is determined based on the correction amount for each pressure chamber and the rate of change in the characteristic value of the liquid with respect to the application of a voltage to the pressure chamber. The method for adjusting the ejection characteristics of a liquid jet head according to claim 2 .

4. The inclination of the polarization direction itself from the initial state is individually adjusted in advance for each pressure chamber. The variation in the ejection characteristics of the liquid among the plurality of nozzles is suppressed. The method for adjusting the ejection characteristics of a liquid jet head according to any one of claims 1 to 3.

5. After individually pre-adjusting the inclination of the polarization direction itself from the initial state for each pressure chamber, An aging process is further performed to stabilize the polarization state within the piezoelectric substrate. The method for adjusting the ejection characteristics of a liquid jet head according to any one of claims 1 to 3.

6. When the voltage waveform is applied to the piezoelectric substrate, the piezoelectric substrate is set to a temperature higher than room temperature. The method for adjusting the ejection characteristics of a liquid jet head according to any one of claims 1 to 3.

7. During the correction process, a moving average relating to the arrangement distribution of the pressure chambers in the ejection characteristics of the liquid is used to derive a correction amount for each of the pressure chambers. The method for adjusting the ejection characteristics of a liquid jet head according to any one of claims 1 to 3.

8. A predetermined upper limit value is set for the correction amount for each pressure chamber in the correction process. The method for adjusting the ejection characteristics of a liquid jet head according to any one of claims 1 to 3.

9. The ejection characteristics include at least one of the ejection speed of the liquid, the droplet volume of the liquid, and the concentration distribution of the liquid on the recording medium. The method for adjusting the ejection characteristics of a liquid jet head according to any one of claims 1 to 3.

10. The voltage waveform to be corrected in the correction process includes at least one of a voltage application time, a voltage value, and a voltage polarity. The method for adjusting the ejection characteristics of a liquid jet head according to any one of claims 1 to 3.

11. When individually pre-adjusting the inclination of the polarization direction itself from the initial state, the application direction of the voltage waveform for each pressure chamber is made different from the polarization direction in the initial state within the piezoelectric substrate. The method for adjusting the ejection characteristics of a liquid jet head according to any one of claims 1 to 3.

12. When individually pre-adjusting the tilt of the polarization direction itself from the initial state, the application direction of the voltage waveform for each pressure chamber is made perpendicular to the polarization direction in the initial state within the piezoelectric substrate. The method for adjusting the ejection characteristics of a liquid jet head according to claim 11.

13. an ejection unit having a plurality of nozzles for ejecting liquid and a piezoelectric substrate including a plurality of pressure chambers that are individually connected to the plurality of nozzles and are filled with the liquid; a voltage application unit that applies a voltage waveform for adjusting characteristics to the piezoelectric substrate for each pressure chamber; Equipped with The voltage application unit By performing a predetermined correction process on the voltage waveform, the tilt of the polarization direction itself in the piezoelectric substrate from the initial state is individually adjusted in advance for each pressure chamber before the ejection operation of deforming the pressure chamber and ejecting the liquid from the nozzle. Liquid injection head.

14. A liquid jet head according to claim 13 is provided. Liquid jet recording device.

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