Liquid ejecting head and liquid ejecting recording apparatus

Abstract

The invention provides a liquid ejecting head and the like which can easily improve the ejection stability of liquid. A liquid ejecting head according to one embodiment of the present disclosure includes: an ejecting section having a plurality of nozzles that eject a liquid and a plurality of pressure chambers that separately communicate with the plurality of nozzles and are filled with the liquid; and a drive unit that causes the liquid filled into the pressure chamber to be ejected from the nozzle by driving the ejection unit on the basis of a drive signal having a plurality of pulses in a predetermined printing cycle. The plurality of pulses in the drive signal include: one or more ejection pulses having a pulse width in a range in which the liquid is ejected from the nozzle; and one or a plurality of heat generation pulses that have a pulse width within a range in which the liquid is not discharged from the nozzle, and that adjust the amount of heat generated when the ejection unit is driven.

Description

Technical Field

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

[0002] Liquid ejection recording apparatuses equipped with a liquid ejection head are used in various fields, and various types of liquid ejection heads have been developed as the liquid ejection head (for example, refer to Patent Document 1). Prior Art Documents Patent Documents

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2012-214018. Summary of the Invention Problems to be Solved by the Invention

[0004] In such a liquid ejection head, it is generally required to easily improve the ejection stability of the liquid. Ideally, a liquid ejection head and a liquid ejection recording apparatus that can easily improve the ejection stability of the liquid are provided. Solutions to the Problems

[0005] The liquid ejection head according to one embodiment of the present disclosure includes: an ejection unit having a plurality of nozzles that eject liquid and a plurality of pressure chambers that communicate individually with the plurality of nozzles and are filled with liquid respectively; and a drive unit that drives the ejection unit based on a drive signal having a plurality of pulses within a predetermined printing cycle, causing the liquid filled in the pressure chambers to be ejected from the nozzles. The plurality of pulses in the drive signal include: one or more ejection pulses having a pulse width within a range where liquid is ejected from the nozzles; and one or more heating pulses having a pulse width within a range where liquid is not ejected from the nozzles and adjusting the amount of heat generated when driving the ejection unit.

[0006] The liquid ejection recording apparatus according to one embodiment of the present disclosure includes the liquid ejection head according to one embodiment of the present disclosure. Effects of the Invention

[0007] According to the liquid ejection head and the liquid ejection recording apparatus according to one embodiment of the present disclosure, the ejection stability of the liquid can be easily improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic perspective view showing a schematic configuration example of a liquid ejection recording apparatus according to one embodiment of the present disclosure. Figure 2 It shows Figure 1 a schematic configuration example of the liquid ejection head shown. Figure 3 It shows Figure 1Exploded perspective view of a detailed configuration example of the liquid ejection head shown. Figure 4 It shows Figure 3 Schematic diagram of a planar configuration example of an actuator plate or the like shown. Figure 5 It shows along Figure 4 Schematic diagram of a cross-sectional configuration example along the V-V line shown. Figure 6 It shows along Figure 4 Schematic diagram of a cross-sectional configuration example along the VI-VI line shown. Figure 7 It is a schematic cross-sectional view that magnifies part VII shown in Figure 5 Schematic cross-sectional view showing an enlarged view of part VII shown. Figure 8 Schematic diagram showing an example of the supply path of each potential supplied from the drive unit to the drive electrode. Figure 9 Timing chart schematically showing an example of the waveform of the drive signal. Figure 10 Timing chart schematically showing various waveform examples in the drive signal. Figure 11 Graph showing an example of the correspondence between the drive frequency corresponding to the viscosity of the liquid and the ejection speed of a general liquid ejection head. Figure 12 Graph showing an example of the analysis result of the importance of various parameters contributing to the temperature of the ejection unit. Figure 13 Timing chart schematically showing an example of various pulses in the drive signal related to Comparative Examples 1 and 2 and Example 1. Figure 14 Graph showing an example of the average ejection speed under various conditions related to Comparative Examples 1 and 2 and Example 1. Figure 15 Graph showing another example of the average ejection speed under various conditions related to Comparative Examples 1 and 2 and Example 1. Figure 16 Timing chart schematically showing an example of various pulses in the drive signal related to Example 2. Figure 17 It schematically shows Figure 3 Top view showing an example of the temperature measurement part of the common flow path shown, etc. Figure 18 It shows Figure 17 Graph showing an example of the time change of the temperature at each temperature measurement part shown. Figure 19This is a schematic top view for explaining an example of the method for adjusting the calorific value involved in Embodiment 3. Detailed implementation mode

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, the description will be carried out in the following order. 1. Embodiment (example applicable to the case of a cyclic liquid ejection head) 2. Modification example

[0010] <1. Embodiment> [A. Overall configuration of printer 1] Figure 1 A schematic perspective view shows a schematic configuration example of a printer 1 which is a liquid ejection recording apparatus according to an embodiment of the present disclosure. The printer 1 is an inkjet printer that records (prints) images, characters, etc. on a recording paper P as a recording medium using ink 9 described later. In addition, as this recording medium, it is not limited to paper, and includes materials that can be recorded such as ceramics or glass.

[0011] As Figure 1 shown, the printer 1 includes a pair of conveying mechanisms 2a, 2b, an ink tank 3, an inkjet head 4, an ink supply pipe 50, and a scanning mechanism 6. These components are accommodated in a housing 10 having a predetermined shape. In this embodiment, although the details will be described later, a cyclic inkjet head that circulates ink 9 between the ink tank 3 and the inkjet head 4 will be exemplified.

[0012] In addition, in each of the accompanying drawings used in the description of this specification, the scale of each component is appropriately changed so that each component can be recognized in size.

[0013] Here, the printer 1 corresponds to a specific example of the "liquid ejection recording apparatus" in the present disclosure, and the inkjet head 4 (the inkjet heads 4Y, 4M, 4C, 4K described later) corresponds to a specific example of the "liquid ejection head" in the present disclosure. In addition, the ink 9 corresponds to a specific example of the "liquid" in the present disclosure. In addition, as the "liquid" in the present disclosure, it is not limited to the ink 9 ("general ink for image formation") described in this embodiment.

[0014] As Figure 1 shown, the conveying mechanisms 2a, 2b are mechanisms that convey the recording paper P along the conveying direction d (X-axis direction). These conveying mechanisms 2a, 2b each have a grid roller 21, a pinch roller 22, and a driving mechanism (not shown). This driving mechanism is a mechanism that rotates the grid roller 21 around an axis (rotates in the Z-X plane), and is composed of, for example, a motor.

[0015] (Ink tank 3) The ink tank 3 is a tank that holds ink 9 inside. In this example, as the ink tank 3, Figure 1 shown, there are provided four types of tanks that separately hold the ink 9 of four colors: yellow (Y), magenta (M), cyan (C), and black (K). That is, there is provided an ink tank 3Y that holds the yellow ink 9, an ink tank 3M that holds the magenta ink 9, an ink tank 3C that holds the cyan ink 9, and an ink tank 3K that holds the black ink 9. These ink tanks 3Y, 3M, 3C, and 3K are arranged side by side in the frame 10 along the X-axis direction.

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

[0017] (Inkjet head 4) The inkjet head 4 is a head that ejects (spits out) droplet-shaped ink 9 from a plurality of nozzles (nozzle holes Hn) described later onto the recording paper P to record (print) images, characters, etc. In this example, as the inkjet head 4, Figure 1 shown, there are also provided four types of heads that separately eject the ink 9 of four colors held in the above-described ink tanks 3Y, 3M, 3C, and 3K. That is, there is provided an inkjet head 4Y that ejects the yellow ink 9, an inkjet head 4M that ejects the magenta ink 9, an inkjet head 4C that ejects the cyan ink 9, and an inkjet head 4K that ejects the black ink 9. These inkjet heads 4Y, 4M, 4C, and 4K are arranged side by side in the frame 10 along the Y-axis direction.

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

[0019] The ink supply pipe 50 is a pipe that supplies the ink 9 from inside the ink tank 3 into the inkjet head 4. The ink supply pipe 50 is, for example, composed of a flexible hose having a degree of flexibility that can follow the movement of the scanning mechanism 6 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 Figure 1 shown, the scanning mechanism 6 has: a pair of guide rails 61a and 61b that extend along the Y-axis direction, a carriage 62 that is supported movably by these guide rails 61a and 61b, and a drive mechanism 63 that moves the carriage 62 along the Y-axis direction.

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

[0022] In addition, the scanning mechanism 6 and the aforementioned conveying mechanisms 2a and 2b constitute a moving mechanism that relatively moves the inkjet head 4 and the recording paper P. However, the moving mechanism is not limited to such a configuration. For example, it may be the following configuration (so-called "single pass method"): by fixing the inkjet head 4 and moving only the recording medium (recording paper P) at the same time, the inkjet head 4 and the recording medium are relatively moved.

[0023] [B. Detailed Configuration of Inkjet Head 4] Next, with reference to Figures 2 to 7 a detailed configuration example of the inkjet head 4 will be described.

[0024] Figure 2 Schematically shows a schematic configuration example of the inkjet head 4. In addition, in this Figure 2 for convenience, the illustration of the cover plate 43 described later is omitted. Figure 3 Shows the detailed configuration example of the inkjet head 4 shown in Figure 1 exploded perspective view. Figure 4 Schematically shows Figure 3 a plan view configuration example (X-Y plane configuration example) of the actuator plate 42 and the like shown in Figure 4 For convenience, the actuator plate 42 in the inkjet head 4 is selectively shown. Figure 5 Schematically shows along Figure 4 a cross-sectional configuration example (Z-X cross-sectional example) of the V-V line shown in Figure 6 Schematically shows along Figure 4 a cross-sectional configuration example (Z-Y cross-sectional example) of the VI-VI line shown in Figure 7 The Figure 5 VII part shown in is enlarged and schematically shown in a cross-sectional view (Z-X cross-sectional view).

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

[0026] In addition, the nozzle plate 41, the actuator plate 42, and the cover plate 43 correspond to a specific example of the "jetting unit" in the present disclosure.

[0027] These nozzle plate 41, actuator plate 42, and cover plate 43 are, for example, bonded to each other using an adhesive or the like and laminated in this order along the Z-axis direction. Additionally, a flow path plate (not shown) having a predetermined flow path may be provided on the upper surface of the cover plate 43. Further, hereinafter, the cover plate 43 side will be appropriately referred to as the upper side and the nozzle plate 41 side will be referred to as the lower side along the Z-axis direction for explanation.

[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 jetting ink 9 (refer to Figures 2 to 7 ). These nozzle holes Hn are respectively formed side by side at a predetermined interval on a straight line (in this example, along the X-axis direction). Additionally, as Figure 3 , Figure 4 shows, in this nozzle plate 41, two nozzle rows (nozzle rows 411, 412) extending respectively along the X-axis direction are provided. These nozzle rows 411, 412 are arranged at a predetermined interval from each other along the Y-axis direction. In this way, this inkjet head 4 becomes a two-row type inkjet head.

[0029] The nozzle row 411 has a plurality of nozzle holes H1 formed side by side at a predetermined interval on a straight line along the X-axis direction. These nozzle holes H1 respectively penetrate the nozzle plate 41 along its thickness direction (Z-axis direction) and communicate with the discharge channel C1e of the actuator plate 42 described later. Specifically, as Figure 4 shows, each nozzle hole H1 is formed so as to be located at the central portion along the Y-axis direction on the discharge channel C1e. Additionally, the formation pitch of the nozzle holes H1 along the X-axis direction is the same as the formation pitch of the discharge channel C1e along the X-axis direction (same pitch). From the nozzle holes H1 in such a nozzle row 411, the ink 9 supplied from the discharge channel C1e is discharged (jetted), the details of which will be described later.

[0030] The nozzle row 412 similarly has a plurality of nozzle holes H2 formed side by side at a predetermined interval on a straight line along the X-axis direction. These nozzle holes H2 also respectively penetrate the nozzle plate 41 along its thickness direction and communicate with the discharge channel C2e of the actuator plate 42 described later. Specifically, as Figure 4As shown, each nozzle hole H2 is formed so as to be located at the central portion along the Y-axis direction in the discharge passage C2e. In addition, the formation pitch of the nozzle holes H2 along the X-axis direction is the same as the formation pitch of the discharge passage C2e along the X-axis direction. From the nozzle holes H2 in such a nozzle row 412 as well, as will be described in detail later, ink 9 supplied from within the discharge passage C2e is discharged.

[0031] In addition, these nozzle holes Hn (H1, H2) are each a tapered through-hole that gradually decreases in diameter toward the lower side (see Figure 2 , Figures 5 to 7 ), which corresponds to a specific example of the "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), for example. Although details will be described later, it changes the volumes within the discharge passages C1e and C2e described later. The actuator plate 42 is composed 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 can also be constituted by laminating two piezoelectric substrates having different polarization directions along the thickness direction (Z-axis direction) (so-called herringbone type).

[0033] In addition, as Figure 3 , Figure 4 shown, on the actuator plate 42, there are provided two rows of channels (channel rows 421, 422) extending respectively along the X-axis direction. These channel rows 421, 422 are arranged at a predetermined interval from each other along the Y-axis direction.

[0034] On such an actuator plate 42, as Figure 4 shown, the central portion along the X-axis direction (formation region of the channel rows 421, 422) becomes the discharge region (spray region) of the ink 9. On the other hand, on the actuator plate 42, the both end portions along the X-axis direction (non-formation region of the channel rows 421, 422) become the non-discharge region (non-spray region) of the ink 9. This non-discharge region is located outside along the X-axis direction with respect to the above-mentioned discharge region. In addition, both end portions of the actuator plate 42 along the Y-axis direction respectively constitute tails 420 (see Figure 4 ).

[0035] As Figure 3 , Figure 4 shown, the above-mentioned channel row 421 has a plurality of channels C1 extending along the Y-axis direction. These channels C1 are arranged side by side in parallel at a predetermined interval from each other along the X-axis direction. As Figure 3 ,Figure 5 , Figure 7 As shown in Figure 7 , each channel C1 is separately formed by being partitioned by a drive wall Wd made of a piezoelectric body (actuator plate 42), and becomes a concave groove portion in a cross-sectional view.

[0036] As Figure 3 , Figure 4 shown in Figure 4 , the channel row 422 also similarly has a plurality of channels C2 extending along the Y-axis direction. These channels C2 are arranged side by side in a manner parallel to each other at a predetermined interval along the X-axis direction. In addition, as Figure 3 shown in Figure 3 , each channel C2 is also separately formed by being partitioned by the above-described drive wall Wd, and becomes a concave groove portion in a cross-sectional view. Furthermore, although details will be described later, each drive wall Wd functions as an element (piezoelectric element) for individually pressurizing each of the channels C1, C2 (each discharge channel C1e, C2e described later).

[0037] Here, as Figures 3 to 5 shown in Figures 3 to 5 , in the channel C1, there are a discharge channel C1e for discharging (filling) the ink 9 and a dummy channel C1d for not discharging (not filling) the ink 9. In the channel row 421, these discharge channels C1e and dummy channels C1d are alternately arranged along the X-axis direction via the above-described drive wall Wd. The plurality of discharge channels C1e are individually connected to the plurality of nozzle holes H1 of the nozzle plate 41, while on the other hand, the plurality of dummy channels C1d are not connected to these nozzle holes H1 and are covered from below by the upper surface of the nozzle plate 41 (see Figure 5 ).

[0038] Similarly, as Figure 3 , Figure 4 shown in Figure 4 , in the channel C2, there are a discharge channel C2e for discharging (filling) the ink 9 and a dummy channel C2d for not discharging (not filling) the ink 9. In the channel row 422, these discharge channels C2e and dummy channels C2d are alternately arranged along the X-axis direction via the above-described drive wall Wd. The plurality of discharge channels C2e are individually connected to the plurality of nozzle holes H2 of the nozzle plate 41, while on the other hand, the plurality of dummy channels C2d are not connected to these nozzle holes H2 and are covered from below by the upper surface of the nozzle plate 41.

[0039] In addition, such discharge channels C1e, C2e respectively correspond to a specific example of the "pressure chamber" in the present disclosure.

[0040] As Figure 3 , Figure 4As shown, the discharge channel C1e and the dummy channel C1d of channel C1 are arranged in a manner different from the discharge channel C2e and the dummy channel C2d of channel C2. Therefore, in the inkjet head 4, the discharge channel C1e of channel C1 and the discharge channel C2e of channel C2 are arranged in a staggered manner. In addition, as Figure 3 shown, in the actuator plate 42, shallow groove portions Dd communicating with the outer ends in the Y-axis direction of the dummy channels C1d and C2d are formed in portions corresponding to the dummy channels C1d and C2d.

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

[0042] Here, as Figure 3 , Figure 5 , Figure 7 shown, drive electrodes Ed extending in the Y-axis direction are respectively provided on the opposing inner side surfaces of the above-described drive walls Wd. That is, a pair of drive electrodes Ed are arranged to oppose each other with each drive wall Wd interposed therebetween. In this drive electrode Ed, there are a common electrode Edc (common electrode) provided on the inner side surface facing the discharge channels C1e and C2e and a separate electrode Eda (active electrode) provided on the inner side surface facing the dummy channels C1d and C2d. In addition, as Figure 3 , Figure 5 , Figure 7 shown, such drive electrodes Ed (common electrode Edc and separate electrode Eda) are formed only up to an intermediate position in the depth direction (Z-axis direction) on the inner side surface of the drive wall Wd.

[0043] A pair of common electrodes Edc opposing each other within the same discharge channel C1e (or discharge channel C2e) are electrically connected to each other at a common terminal (not shown). In addition, a pair of separate electrodes Eda opposing each other within the same dummy channel C1d (or dummy channel C2d) are electrically separated from each other. On the other hand, a pair of separate electrodes Eda opposing each other via the discharge channel C1e (or discharge channel C2e) are electrically connected to each other at a separate terminal (not shown).

[0044] Here, in the aforementioned tail portion 420, as Figure 3As shown, a flexible printed circuit board 493 is installed for electrically connecting the drive electrode Ed and the drive unit 49. A wiring pattern (not shown) formed on the flexible printed circuit board 493 is electrically connected to the above-mentioned common terminal and individual terminal. Thus, a drive voltage Vd (drive signal Sd) etc. described later is applied to each drive electrode Ed from the drive unit 49 described later via the flexible printed circuit board 493 (refer to Figure 2 ).

[0045] (B-3. Cover plate 43) As Figure 3 , Figures 5 to 7 shown, the cover plate 43 is arranged so as to block each channel C1, C2 (each channel row 421, 422) of 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] In the cover plate 43, as Figure 3 , Figure 6 shown, a pair of supply-side common flow paths Rin1, Rin2 and a pair of recovery-side common flow paths Rout1, Rout2 are respectively formed. In addition, as Figure 6 shown, wall portions W1, W2 are formed in the cover plate 43.

[0047] The wall portion W1 is arranged so as to cover the upper part of the discharge channel C1e and the dummy channel C1d, and the wall portion W2 is arranged so as to cover the upper part of the discharge channel C2e and the dummy channel C2d (refer to Figure 6 ).

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

[0049] The supply-side common flow path Rin1 is formed near the end portion on the inner side (the side of the wall portion W1) along the Y-axis direction of each channel C1 and becomes a concave groove portion (refer to Figure 3 , Figure 6)。In the supply - side common flow path Rin1, in the region corresponding to each discharge channel C1e, a supply slit Sin1 that penetrates the cover plate 43 in its thickness direction (Z - axis direction) is formed (refer to Figure 3 , Figure 6 ). Similarly, the supply - side common flow path Rin2 is formed near the end of each channel C2 on the inner side (the side of the wall portion W2) along the Y - axis direction, and becomes a concave groove portion (refer to Figure 3 , Figure 6 ). In this supply - side common flow path Rin2, in the region corresponding to each discharge channel C2e, a supply slit Sin2 that penetrates the cover plate 43 in its thickness direction is also formed (refer to Figure 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 becomes a concave groove portion (refer to Figure 3 , Figure 6 ). In this recovery - side common flow path Rout1, in the region corresponding to each discharge channel C1e, a recovery slit Sout1 that penetrates the cover plate 43 in its thickness direction is formed (refer to Figure 3 , Figure 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 becomes a concave groove portion (refer to Figure 3 , Figure 6 ). In this recovery - side common flow path Rout2, in the region corresponding to each discharge channel C2e, a recovery slit Sout2 that penetrates the cover plate 43 in its thickness direction is also formed (refer to Figure 3 ).

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

[0052] In this way, the supply - side common flow path Rin1 and the recovery - side common flow path Rout1 are respectively connected to each discharge channel C1e via the supply slit Sin1 and the recovery slit Sout1 (refer to Figure 3 , Figure 6)。In addition, the supply slit Sin1 and the recovery slit Sout1 respectively serve as through-holes through which the ink 9 flows between the ejection channels C1e. Specifically, the supply-side common flow path Rin1 supplies the ink 9 into the ejection channel C1e via the supply slit Sin1, and the recovery-side common flow path Rout1 recovers the ink 9 from within the ejection channel C1e via the recovery slit Sout1 (refer to the dotted arrows in Figure 6 ). On the other hand, in each dummy channel C1d, neither the supply-side common flow path Rin1 nor the recovery-side common flow path Rout1 is connected. Specifically, each dummy channel C1d is blocked by the bottoms of these supply-side common flow path Rin1 and recovery-side common flow path Rout1.

[0053] Similarly, the supply-side common flow path Rin2 and the recovery-side common flow path Rout2 are respectively connected to the respective ejection channels C2e via the supply slit Sin2 and the recovery slit Sout2 (refer to Figure 3 ). In addition, the supply slit Sin2 and the recovery slit Sout2 respectively serve as through-holes through which the ink 9 flows between the ejection channels C2e. Specifically, the supply-side common flow path Rin2 supplies the ink 9 into the ejection channel C2e via the supply slit Sin2, and the recovery-side common flow path Rout2 recovers the ink 9 from within the ejection channel C2e via the recovery slit Sout2. On the other hand, in each dummy channel C2d, neither the supply-side common flow path Rin2 nor the recovery-side common flow path Rout2 is connected (refer to Figure 6 ). Specifically, each dummy channel C2d is blocked by the bottoms of these supply-side common flow path Rin2 and recovery-side common flow path Rout2 (refer to Figure 6 ).

[0054] (B-4. Driving Unit 49) As shown in Figure 2 , the driving unit 49 performs ejection driving of the ink 9 using the driving signal Sd (driving voltage Vd). At this time, the driving unit 49 outputs such a driving signal Sd (driving voltage Vd) based on various data (signals) supplied from a printing control unit (not shown) inside the printer 1 (inside the inkjet head 4).

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

[0056] [C. Details of Driving Voltage Vd and Driving Signal Sd] Next, with reference to Figures 8 to 10 examples of the detailed configurations of the above driving voltage Vd and driving signal Sd will be described.

[0057] Figure 8 Schematically shows an example of the supply path of each potential supplied from the driving unit 49 to the driving electrodes Ed (individual electrode Eda and common electrode Edc). Specifically, in this Figure 8 example, examples of the supply paths related to the channel C1 are shown for the potential supplied to the individual electrode Eda (individual potential Vda) and the potential supplied to the common electrode Edc (common potential Vdc), respectively.

[0058] In addition, for convenience, in Figure 8 the illustration is omitted, but the same applies to the example of the supply path related to the channel C2 (examples of the supply paths of the individual potential Vda and the common potential Vdc).

[0059] In addition, Figure 9 schematically shows an example of the waveform of the driving signal Sd in a timing diagram. Figure 10 Schematically shows various waveform examples in the driving signal Sd in a timing diagram.

[0060] In addition, in Figure 9 , Figure 10 the vertical axis represents the voltage value of the driving voltage Vd (equivalent to the potential difference between the above individual potential Vda and common potential Vdc: Vd = Vda - Vdc), and the horizontal axis represents time t. In addition, the magnitude of such a driving voltage Vd corresponds to the volumes of the above discharge channels C1e and C2e. Moreover, the cases where the driving voltage Vd is a positive (+) value, a negative (-) value, the states where their volumes are more expanded than the reference value, and the states where they are more contracted than the reference value are shown respectively (refer to Figure 9 ).

[0061] Incidentally, in the example shown in Figure 9 , by setting the common potential Vdc to a predetermined positive potential (Vdc > 0), the driving voltage Vd (the potential difference between the individual potential Vda and the common potential Vdc) is set to a negative value (Vd < 0), but it is not limited to this example. That is, for example, the driving voltage Vd can also be directly set to a negative value (Vd < 0) by setting the common potential Vdc = 0 (ground potential) and setting the individual potential Vda to a predetermined negative potential (Vda < 0). In such a driving case, the same driving (pressure change of the actuator plate 42) as the driving example shown in Figure 9 can also be performed.

[0062] In Figure 9, Figure 10 (A) to Figure 10 In each of the examples shown in (D), the drive signal Sd becomes a signal having a plurality of pulses (pulses p1, p2) within one cycle (printing cycle Tp described below) (a signal to which the so-called "multi-pulse method" is applied). Pulse p1 is a pulse (expansion pulse) for expanding the volume of the discharge channels C1e, C2e, and pulse p2 is a pulse (contraction pulse) for contracting the volume of the discharge channels C1e, C2e. In addition, in Figure 10 (A) to Figure 10 In each of the examples shown in (D), among the plurality of pulses within one cycle (printing cycle Tp), the first pulse becomes pulse p1, and the last pulse becomes pulse p2. However, the first pulse within the printing cycle Tp may be either pulse p1 (expansion pulse) or pulse p2 (contraction pulse).

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

[0064] Here, in the present embodiment, although the details will be described later, as the plurality of pulses in the above-mentioned drive signal Sd, the following pulses are included. That is, first, in the drive signal Sd, one or more discharge pulses Pj having a pulse width Wj within the range (degree) of discharging the ink 9 from the nozzle hole Hn are included. In addition, although the details will be described later, this discharge pulse Pj corresponds to the aggregate of the above-mentioned pulses p1, p2. In addition, in the drive signal Sd, one or more heating pulses Ph are included: having a pulse width Wh within the range (degree) where the ink 9 is not discharged from the nozzle hole Hn (corresponding to the pulse widths Wh1, Wh2 described later), and adjusting the calorific value Δh generated during the above-mentioned driving by the driving unit 49.

[0065] Incidentally, the pulse width Wh within the range where the ink 9 is not discharged from the nozzle hole Hn is, for example, about 1 / 6 to 1 / 3 of the resonance period (AP: Acoustic Period). That is, as the range of the pulse width Wh, for example, (AP / 6) ≦ Wh ≦ (AP / 3) can be cited. On the other hand, the pulse width Wj within the range where the ink 9 is discharged from the nozzle hole Hn is, for example, a range larger than the above-mentioned pulse width Wh. That is, as the range of the pulse width Wj, for example, (AP / 3) < Wj can be cited.

[0066] In addition, the above-mentioned AP corresponds to a period that is 1 / 2 of the natural vibration period of the ink 9 in the ejection channels C1e and C2e (1AP = (natural vibration period of the ink 9) / 2). Moreover, when the pulse width of a certain pulse is set to AP, when ejecting a normal one-drop amount of the ink 9 (ejecting one drop), the ejection speed (ejection efficiency) of the ink 9 is the maximum. Additionally, this AP is defined, for example, based on the shapes of the ejection channels C1e and C2e, the physical property values (specific gravity, etc.) of the ink 9, and the like.

[0067] In addition, the details of such ejection pulses Pj and heating pulses Ph will be described later ( Figures 13 to 19 ).

[0068] [Operation and Function / Effect] (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. In addition, as the initial state, in Figure 1 the four types of ink cartridges 3 (3Y, 3M, 3C, 3K) shown, the corresponding colors (four colors) of the ink 9 are sufficiently sealed respectively. Additionally, the ink 9 in the ink cartridge 3 is in a state of being filled into the inkjet head 4 via the ink supply pipe 50.

[0069] In such an initial state, if the printer 1 is operated, the grid rollers 21 of the conveying mechanisms 2a and 2b rotate respectively, so that between the grid roller 21 and the pinch roller 22, the recording paper P is conveyed along the conveying direction d (X-axis direction). Additionally, simultaneously with such a conveying operation, the drive motor 633 of the drive mechanism 63 rotates the pulleys 631a and 631b respectively, so that the endless belt 632 operates. Thereby, the carriage 62 is guided by the guide rails 61a and 61b and simultaneously reciprocates along the width direction (Y-axis direction) of the recording paper P. Moreover, at this time, by appropriately ejecting the four-color ink 9 onto the recording paper P using each inkjet head 4 (4Y, 4M, 4C, 4K), the recording operation of images, characters, etc. on the recording paper P is performed.

[0070] (B. Detailed Operation of Inkjet Head 4) Next, the detailed operation of the inkjet head 4 will be described.

[0071] First, in this inkjet head 4, the ejection operation of the ink 9 using the shear mode is performed as follows. In other words, by performing the ejection drive of the actuator plate 42 from the drive unit 49 using the aforementioned drive signal Sd, the ink 9 filled into the ejection channels C1e and C2e is ejected from the nozzle holes Hn.

[0072] During such ejection driving, the driving unit 49 applies a driving voltage Vd (driving signal Sd) to the driving electrodes Ed (common electrode Edc and individual electrode Eda) in the actuator plate 42. Specifically, the driving unit 49 applies the driving voltage Vd to the driving electrodes Ed (common electrode Edc and individual electrode Eda) provided on each of the pair of driving walls Wd that define the ejection channels C1e and C2e. As a result, the pair of driving walls Wd are deformed so as to protrude toward the dummy channels C1d and C2d adjacent to the ejection channels C1e and C2e, respectively.

[0073] Here, as described above, in the actuator plate 42, the polarization direction is set in one direction, and the driving electrodes Ed are formed only at an intermediate position in the depth direction on the inner side surface of the driving wall Wd. Therefore, by applying the driving voltage Vd by the driving unit 49, the driving wall Wd is bent and deformed in a V shape with the intermediate position in the depth direction of the driving wall Wd as the center. Moreover, by such bending deformation of the driving wall Wd, the ejection channels C1e and C2e are deformed as if bulging (refer to the expansion direction d11 shown in Figure 7 .

[0074] Incidentally, when the configuration of the actuator plate 42 is not such a cantilever type but the herringbone type described above, the driving wall Wd is bent and deformed in a V shape as follows. That is, in the case of the herringbone type, the polarization direction of the actuator plate 42 is different along the thickness direction (the two piezoelectric substrate layers are laminated), and the driving electrodes Ed are formed over the entire depth direction on the inner side surface of the driving wall Wd. Therefore, by applying the driving voltage Vd by the above-described driving unit 49, the driving wall Wd is bent and deformed in a V shape with the intermediate position in the depth direction of the driving wall Wd as the center. As a result, in this case, by such bending deformation of the driving wall Wd, the ejection channels C1e and C2e are also deformed as if bulging (refer to the expansion direction d11 shown in Figure 7 .

[0075] In this way, the volume of the ejection channels C1e and C2e is increased by the bending deformation caused by the piezoelectric thickness sliding effect at the pair of driving walls Wd. Moreover, since the volume of the ejection channels C1e and C2e is increased, the ink 9 stored in the supply side common flow paths Rin1 and Rin2 is guided into the ejection channels C1e and C2e through the supply slits Sin1 and Sin2 (for example, refer to the dotted arrows in Figure 6 ).

[0076] Next, the ink 9 guided into the ejection channels C1e and C2e in this way becomes a pressure wave and propagates inside the ejection channels C1e and C2e. Moreover, at the moment when this pressure wave reaches the nozzle holes Hn of the nozzle plate 41 (or at a moment before or after that), the drive voltage Vd applied to the drive electrode Ed becomes 0 (zero) V. As a result, the drive wall Wd returns from the above-described bent and deformed state, and as a result, the volumes of the ejection channels C1e and C2e that have temporarily increased return to their original state again (for example, refer to Figure 7 the contraction direction db shown in

[0077] ). In this way, during the process in which the volumes of the ejection channels C1e and C2e return to their original state, the pressure inside the ejection channels C1e and C2e increases, and the ink 9 inside the ejection channels C1e and C2e is pressurized. As a result, the droplet-shaped ink 9 is ejected to the outside (toward the recording paper P, etc.) through the nozzle holes Hn (refer to Figure 2 、 Figures 5 to 7 ). In this way, the ejection operation (ejection operation) of the ink 9 of the inkjet head 4 is performed, and as a result, the recording operation (printing operation) of an image, characters, etc. on the recording paper P is performed.

[0078] In addition, a part of the ink 9 filled in the ejection channels C1e and C2e is recovered into the common recovery channels Rout1 and Rout2 on the recovery side through the recovery slits Sout1 and Sout2 (for example, refer to the dotted arrows in Figure 6 ). In addition, the ink 9 recovered into these common recovery channels Rout1 and Rout2 returns from inside the inkjet head 4 to the ink tank 3 through the ink supply pipe 50. In this way, the circulation operation of the ink 9 is performed.

[0079] (C. Regarding the adjustment of the calorific value using the heating pulse Ph) Next, the adjustment of the calorific value using the aforementioned heating pulse Ph in the present embodiment (the adjustment of the calorific value Δh generated when the actuator plate 42, etc. is driven by the drive unit 49) will be described in detail.

[0080] (C-1. Conventional method) First, in conventional inkjet heads, generally, in the case of using ink with a high viscosity, around 20 (mPa·s) becomes the upper limit value of the viscosity at which ink can be stably ejected. Moreover, in the case of using ink with a higher viscosity than this, a mechanism for heating the ink tank or the inkjet head itself to reduce the viscosity of the ink is required. Therefore, in the conventional method, problems such as complication of the configuration, increase in the device price, and increase in power consumption occur, and it is difficult to improve the ejection stability of the ink. Additionally, for example, although by increasing the displacement amount at the actuator plate, ink with a high viscosity exceeding the above-mentioned 20 (mPa·s) can be ejected, due to the influence of heat generated when the actuator plate or the like is driven, there is also a problem that the ejection speed of the ink varies corresponding to the drive frequency and ejection ratio.

[0081] Here, Figure 11 An example (in the case where the drive voltage Vd is constant) showing the correspondence between the drive frequency fd during ejection drive and the ejection speed Vj of ink 9 corresponding to the viscosity Vi of conventional general inkjet heads is presented. In addition, in this Figure 11 the vertical axis shows the difference value ΔVj of the ejection speed Vj based on the ejection speed Vj when the drive frequency fd = 2 (kHz). Additionally, in this Figure 11 the ejection speed Vj in this is transformed by calculation with the drive voltage Vd required to obtain this speed as the vertical axis when the speed is constant, and thus becomes a value representing the ejection speed Vj. In the example shown in this Figure 11 it can be seen that if ejection drive is performed, the temperature of the ink rises due to heat generation in the actuator plate or the like, resulting in low viscosity of the ink. Therefore, at the same drive voltage Vd, as the drive frequency fd increases, the ejection speed Vj increases and the ejection speed Vj varies. Additionally, it can be seen that at the same drive frequency fd, as the viscosity Vi increases, the ejection speed Vj increases and the ejection speed Vj varies (refer to the arrow of the dashed line in Figure 11 ).

[0082] Due to these, it is desired to propose the following method: Even in the case of ejecting ink 9 with a high viscosity, it is easy to suppress deviations in the ejection characteristics of ink 9 (such as deviations in the ejection speed Vj), and it is possible to easily improve the ejection stability (uniformity, suitability) of ink 9.

[0083] (C-2. Method of this Embodiment) Thus, in the inkjet head 4 of the present embodiment, as multiple pulses in the drive signal Sd, in addition to the aforementioned ejection pulse Pj, it further includes a heating pulse Ph for adjusting the calorific value Δh generated during the above-described driving by the drive unit 49. Moreover, by including such a heating pulse Ph in the drive signal Sd, the actuator plate 42 itself and the like are heated, and the ink 9 in the ejection channels C1e and C2e is heated, thereby reducing the viscosity of the ink 9 to a viscosity capable of ejection (performing preliminary heating). In addition, the detailed situation will be described later (refer to Figure 18 ), but before the temperature of the ink 9 rises and converges, some time is required. Therefore, by driving the actuator plate 42 and the like to perform the above-described preliminary heating, the viscosity of the ink 9 is reduced to a viscosity that is easy to eject.

[0084] In addition, as a method for adjusting the calorific value Δh using such a heating pulse Ph, in the present embodiment, as an example, the calorific value Δh is adjusted corresponding to the number of pulses Np of the heating pulse Ph included in the printing cycle Tp. In addition, as other methods, for example, the drive voltage Vd, the pulse width Wh of the heating pulse Ph, etc. can be cited.

[0085] Figure 12 An example of the analysis result of the importance degree of various parameters contributing to the temperature of the actuator plate 42 and the like is shown. In this Figure 12 shown analysis result of the importance degree, it can be seen that the contribution rate of the drive frequency fd is the highest. Next, in the order of the number of pulses Np of the heating pulse Ph and the drive voltage Vd, the contribution rate becomes higher. However, in the case of using the drive frequency fd to adjust the calorific value, the degree of freedom of the head performance of the inkjet head 4 becomes lower. Therefore, it can be seen that it is meaningful to use the number of pulses Np of the heating pulse Ph to adjust the calorific value. That is, it can be said that it is easier to adjust the calorific value Δh using the number of pulses Np compared to the cases of using the drive frequency fd, the drive voltage Vd, the pulse width Wh, etc.

[0086] Here, Figure 13 An example of various pulses in the drive signal Sd related to Comparative Example 1, 2 and Example 1 of the present embodiment is schematically shown in a timing chart. Specifically, Figure 13 (A) to (C) respectively show the drive signals Sd related to Comparative Example 1, Example 1 and Comparative Example 2. In addition, Figure 14 、 Figure 15 An example of the average ejection speed Vj(ave) of the ink 9 under various conditions related to these Comparative Example 1, 2 and Example 1 is respectively shown in a table. In addition, Figure 16 An example of various pulses in the drive signal Sd related to Example 2 of the present embodiment is schematically shown in a timing chart. In addition, in Figure 13 、Figure 16 In all of them, the voltage value of the driving voltage Vd is represented on the vertical axis and the time t is represented on the horizontal axis. Additionally, in Figure 13 the examples of the ejection pulses Pj shown in (A) to (C), for convenience, a plurality of pulses (the aforementioned pulses p1, p2) are illustrated together.

[0087] First, in Figure 13 Comparative Example 1 shown in (A), only the ejection pulses Pj having a specified printing period Tp (= ejection period Tj, driving period Td) are continuously arranged along the time axis. Additionally, in Figure 13 Comparative Example 2 shown in (C), only the ejection pulses Pj having a specified printing period Tp (= ejection period Tj, driving period Td) are continuously arranged along the time axis. However, the printing period Tp in Comparative Example 1 (for example, 12 [kHz]) becomes several times (in this example, 6 times) the value of the printing period Tp in Comparative Example 2 (for example, 2 [kHz]).

[0088] On the other hand, in Figure 13 Example 1 shown in (B), between the ejection pulses Pj having a specified printing period Tp (= ejection period Tj, ≠ driving period Td), one or more heating pulses Ph1 (in this example, 5 heating pulses Ph1) serving as heating pulses Ph are provided. Incidentally, in this Example 1, within the printing period Tp, a plurality of driving periods Td defined by the ejection pulses Pj and the heating pulses Ph1 are provided. Additionally, in Figure 16 Example 2 shown, within at least one driving period Td among the plurality of driving periods Td in the driving signal Sd, one or more heating pulses Ph2 (in this example, a plurality of heating pulses Ph2) serving as heating pulses Ph are further provided. Furthermore, the pulse widths Wh1, Wh2 of such heating pulses Ph1, Ph2 respectively fall within the same range as the aforementioned pulse width Wh (for example, (AP / 6) ≤ Wh1 ≤ (AP / 3), (AP / 6) ≤ Wh2 ≤ (AP / 3)).

[0089] Additionally, in Figure 14 an example of the average ejection speed Vj(ave) of the ink 9 under various conditions shown, first, in Comparative Example 2, due to the low ejection frequency fj and small heat generation amount Δh, the high-viscosity ink 9 cannot be ejected (the same applies to Comparative Example 2 in the following Figure 15 description). On the other hand, in Example 1, by providing the heating pulse Ph1, even if the ejection frequency fj changes from the case in Comparative Example 1, the heat generation amount Δh can be maintained to be the same as that in Comparative Example 1, showing the same average ejection speed Vj(ave) as in the case of Comparative Example 1.

[0090] Additionally, inFigure 15 In an example of the average ejection speed Vj(ave) of the ink 9 under various conditions shown below. That is, in this Figure 15 In the shown Embodiment 1, when the printing rate Rp in the direction (X-axis direction) along the aforementioned nozzle rows 411 and 412 is not 100%, the drive signal Sd corresponding to the nozzle hole Hn corresponding to the non-ejection period also includes the heating pulse Ph. That is, it is set in the following manner: in the drive signal Sd corresponding to the nozzle hole Hn corresponding to the non-ejection period corresponding to the printing content on the recording medium (recording paper P), the heating pulse Ph is also included. Thus, even when the printing rate Rp changes between this Embodiment 1 and Comparative Example 1, the same average ejection speed Vj(ave) can be maintained. In addition, even when the ejection frequency fj changes between this Embodiment 1 and Comparative Example 1, the same average ejection speed Vj(ave) can be maintained. In this way, in this Embodiment 1, the calorific value Δh based on the heating pulse Ph is adjusted so that even when at least one of the ejection frequency fj and the printing rate Rp changes, the variation in the ejection speed Vj of the ink 9 is suppressed.

[0091] In addition, the above-mentioned heating pulse Ph1 corresponds to a specific example of the "first heating pulse" in the present disclosure. Further, the above-mentioned heating pulse Ph2 corresponds to a specific example of the "second heating pulse" in the present disclosure.

[0092] In addition, Figure 17 Schematically shown in a top view (X-Y top view) Figure 3 such as the common flow path (in the Figure 17 example shown, the supply-side common flow path Rin2 and the recovery-side common flow path Rout2) of an example of the temperature measurement site. Figure 18 Indicates Figure 17 an example of the time change of the temperature at each of the temperature measurement sites Pr1 to Pr5 shown. Figure 19 Schematically shown in a top view (X-Y top view) is an example of the method for adjusting the calorific value related to Embodiment 3 of the present embodiment.

[0093] First, for example, as Figure 18 shown, in a plurality of channels C1, C2 along the common flow path (in the Figure 17 example, channel C2), there is a tendency that the longer the time in contact with the actuator plate 42 etc. relative to the flow direction (X-axis direction) of the ink 9, the higher the temperature of the ink 9. That is, in this Figure 18 example, in the order of the temperature measurement sites Pr5, Pr4, Pr3, Pr2, Pr1 (from the upstream side to the downstream side of the ink 9 in the common flow path), the temperature of the ink 9 gradually increases (refer toFigure 18 (the arrow of the dashed line shown in)

[0094] Therefore, for example, in Figure 19 Example 3 shown, the adjustment of the calorific value Δh based on the heating pulse Ph is performed so that the gradient in the heat distribution among the plurality of channels C2 along such a common flow path (the temperature gradient with the temperature rising from the upstream side toward the downstream side) is reduced. Specifically, for example, as Figure 19 shown, the adjustment of the calorific value Δh based on the heating pulse Ph (for example, the adjustment of the pulse number Np of the aforementioned heating pulse Ph) is performed so that the calorific value Δh gradually increases from the downstream side of the ink 9 in the common flow path toward the upstream side. Thereby, the non-uniformity of the temperature of the ink 9 can be suppressed among the plurality of channels C2 along the common flow path, and the non-uniformity of the viscosity of the ink 9 can also be suppressed. As a result, the ejection stability of the ink 9 can be pursued.

[0095] Incidentally, in the cyclic inkjet head 4 as in the present embodiment, there is a tendency that if the flow rate of the ink 9 becomes high (in the case of a high flow rate), the actuator plate 42 and the like are difficult to be thermally saturated due to being cooled by the ink 9, and the temperature gradient in the direction of the nozzle rows 411, 412 becomes large. In this case, it is difficult for the temperature of the ink 9 to rise, and it is also difficult to lower the viscosity of the ink 9. Thus, there is a problem that it is necessary to increase the drive voltage Vd and the like. Therefore, in the cyclic inkjet head 4, by setting the flow rate of the circulating ink 9 to be less than 50 (mL / min), for example, the ejection stability of the ink 9 can be pursued, and the reduction of the drive voltage Vd can also be pursued. In addition, for example, as the flow rate of the ink 9 flowing through each of the channels C1, C2, it can be said that, for example, ideally, it is set to be less than 0.2 (mL / min) on average, and more ideally, it is set to be around 0.13 (mL / min).

[0096] (D. Function / Effect) In this way, in the present embodiment, within the printing cycle Tp in the drive signal Sd, the ejection pulse Pj and the heating pulse Ph are respectively included, and thus as follows. That is, the calorific value Δh generated when driving the actuator plate 42 and the like is adjusted by the heating pulse Ph, and thus the adjustment of such a calorific value Δh becomes easy. Therefore, for example, as described above, even in the case of ejecting a highly viscous ink 9, it is easy to suppress the deviation of the ejection characteristics (ejection speed Vj, etc.) of the ink 9. As a result, in the present embodiment, it is possible to easily improve the ejection stability of the ink 9.

[0097] In addition, in the present embodiment, for example, by applying a heat generation pulse Ph to generate a calorific value Δh that is the same as the temperature at which convergence occurs during continuous driving based on the ejection pulse Pj, the ejection stability of the ink 9 can be further improved. Further, in the present embodiment, the heat generation pulse Ph is always used at the maximum ejection frequency fj in the ejection requirements, and the ejection pulse Pj is used during required ejection, thereby enabling stabilization of the ejection speed Vj. In addition, in the present embodiment, for example, stable ejection of the ink 9 with a high viscosity exceeding 20 (mPa·s) can be performed. Further, within the range that can be actually measured, as an example, it has been confirmed that stable ejection can be performed even when using the ink 9 with a high viscosity of up to about 127 (mPa·s).

[0098] In addition, in the present embodiment, in a case where, in addition to providing the heat generation pulse Ph1 between the ejection pulses Pj within the specified printing cycle Tp, the heat generation pulse Ph2 is also provided within at least one driving cycle Td among a plurality of driving cycles Td, it is as follows. That is, for example, in the driving signals Sd corresponding to the respective nozzle holes Hn, adjustment (fine adjustment, etc.) of the calorific value Δh becomes easy, and thus the ejection stability of the ink 9 can be further improved.

[0099] Further, in the present embodiment, the calorific value Δh is adjusted corresponding to the number of pulses Np of the heat generation pulse Ph included within the printing cycle Tp, and thus it is as follows. That is, for example, compared with the case of adjusting the calorific value using the aforementioned other parameters (driving voltage Vd and / or pulse widths Wh1, Wh2, driving frequency fd, etc.), it is easier to adjust the calorific value Δh, and thus the ejection stability of the ink 9 can be further improved.

[0100] In addition, in the present embodiment, in a case where at least one of the aforementioned ejection frequency fj and printing rate Rp changes, and the calorific value Δh based on the heat generation pulse Ph is adjusted to suppress fluctuations in the ejection speed Vj of the ink 9, it is as follows. That is, even in such a case of parameter change, fluctuations in the ejection speed Vj can be suppressed, and thus the ejection stability of the ink 9 can be further improved.

[0101] In addition, in the present embodiment, when adjusting the calorific value Δh based on the heating pulse Ph so as to reduce the gradient (temperature gradient) in the heat distribution among a plurality of channels C1, C2 along the common flow paths (supply-side common flow paths Rin1, Rin2 and recovery-side common flow paths Rout1, Rout2), it is as follows. That is, the calorific value adjustment is performed so as to reduce the thermal gradient among such a plurality of channels C1, C2, and thus the deviation in the ejection characteristics (ejection speed Vj, etc.) of the ink 9 among the plurality of channels C1, C2 can be further suppressed. As a result, the ejection stability of the ink 9 can be further improved.

[0102] Furthermore, in the present embodiment, in the above-described cyclic inkjet head 4, the calorific value adjustment using the heating pulse Ph as described above is performed, and thus it is as follows. That is, first, in a non-cyclic (a mode in which the ink 9 does not circulate between the ink tank 3 and the inkjet head 4) inkjet head, there is generally a problem that heat accumulates in the inkjet head. Specifically, in the ejection channel, heat is dissipated by the ejection of the ink 9. On the other hand, in the non-ejection channel, such heat dissipation is not performed, and thus a difference in heat accumulation occurs between the channels. In contrast, in the cyclic inkjet head, the ink 9 circulates, and thus the difference in heat accumulation between the channels is prevented, and thus the ejection stability of the ink 9 can be further improved.

[0103] <2. Modification Example> As described above, the present disclosure has been described by way of embodiments and examples, but the present disclosure is not limited to these embodiments and the like, and various modifications can be made.

[0104] For example, in the above-described embodiments and the like, the configuration examples (shape, arrangement, number, etc.) of the respective components of the printer and the inkjet head have been specifically described, but it is not limited to those described in the above-described embodiments and the like, and other shapes, arrangements, numbers, etc. may also be possible. In addition, regarding the values, ranges, magnitude relationships, etc. of various parameters described in the above-described embodiments and the like, it is not limited to those described in the above-described embodiments and the like, and other values, ranges, magnitude relationships, etc. may also be possible.

[0105] Specifically, for example, in the above-described embodiments and the like, examples of the type, number, driving voltage Vd, magnitudes of various frequencies, set values of the pulse width, etc. of the pulses included in the driving signal Sd have been specifically described, but it is not limited to those described in the above-described embodiments and the like.

[0106] In addition, as the structure of the inkjet head, various types of structures can be applied. That is, for example, in the above-described embodiments, etc., a so-called side jet type inkjet head that ejects ink 9 from the central portion in the extending direction of each ejection channel of the actuator plate is exemplified. However, it is not limited to this example. For example, it can also be a so-called edge jet type inkjet head that ejects ink 9 along the extending direction of each ejection channel. In addition, in the above-described embodiments, etc., a circulating type inkjet head that circulates ink 9 between the ink tank 3 and the inkjet head 4 and is utilized is exemplified, but it is not limited to this example. That is, for example, a non-circulating type inkjet head that does not circulate ink 9 between the ink tank 3 and the inkjet head 4 can also apply the present disclosure.

[0107] Furthermore, as the mode of the printer, it is not limited to the mode described in the above-described embodiments, etc. For example, various modes such as the MEMS (Micro Electro Mechanical Systems) mode can be applied.

[0108] In addition, in the above-described embodiments, etc., methods for adjusting the calorific value using heat pulses are described by listing specific examples, but it is not limited to the various methods listed in the above-described embodiments, etc., and other methods can also be used. In addition, for example, two or more of the methods listed in the embodiments, etc., can be appropriately combined and used.

[0109] In addition, the series of processes described in the above-described embodiments, etc., can be performed by hardware (circuit) or by software (program). In the case of being performed by software, the software is composed of a set of programs for executing each function by a computer. Each program can, for example, be pre-loaded into the above computer for use, or can be installed from a network or a recording medium into the above computer for use.

[0110] Furthermore, in the above-described embodiments, etc., as a specific example of the "liquid jet recording device" in the present disclosure, the printer 1 (inkjet printer) is exemplified and described, but it is not limited to this example, and the present disclosure can also be applied to other devices other than inkjet printers. In other words, the "liquid jet head" (inkjet head) of the present disclosure can also be applied to other devices other than inkjet printers. Specifically, for example, the "liquid jet head" of the present disclosure can be applied to a facsimile machine, a printing-on-demand machine, a 3D printed object, an adhesive coating, a device for forming a biological material by ejecting a biological polymer, etc.

[0111] In addition, the various examples described above can be applied in any combination.

[0112] In addition, the effects described in this specification are only examples and are not limited effects, and there may be other effects.

[0113] In addition, the present disclosure can also adopt the following configuration. (1) A liquid ejection head, comprising: An ejection unit having a plurality of nozzles for ejecting a liquid and a plurality of pressure chambers that are individually communicated with the plurality of nozzles and filled with the liquid respectively; and A drive unit that drives the ejection unit based on a drive signal having a plurality of pulses within a predetermined printing cycle, causing the liquid filled in the pressure chamber to be ejected from the nozzle, The plurality of pulses in the drive signal include: One or more ejection pulses having a pulse width within a range where the liquid is ejected from the nozzle; and One or more heating pulses having a pulse width within a range where the liquid is not ejected from the nozzle and adjusting the amount of heat generated when driving the ejection unit. (2) The liquid ejection head according to (1) above, wherein Between the ejection pulses that define the printing cycle, one or more first heating pulses as the heating pulses are provided. (3) The liquid ejection head according to (2) above, wherein The printing cycle has a plurality of drive cycles defined by the ejection pulses and the first heating pulses, Within at least one of the plurality of drive cycles, one or more second heating pulses as the heating pulses are further provided. (4) The liquid ejection head according to any one of (1) to (3) above, wherein The amount of heat generated is adjusted corresponding to the number of pulses of the heating pulses included in the printing cycle. (5) The liquid ejection head according to any one of (1) to (4) above, wherein It is set such that the heating pulses are also included in the drive signal corresponding to the nozzle during the non-ejection period corresponding to the printing content on the recording medium. (6) The liquid ejection head according to any one of (1) to (5) above, wherein When at least one of the ejection frequency when the liquid is ejected from the nozzle and the printing rate on the recording medium changes, The amount of heat generated based on the heating pulses is adjusted to suppress fluctuations in the ejection speed of the liquid. (7) The liquid ejection head according to any one of (1) to (6) above, wherein The aforementioned ejection unit further has a common flow path of the aforementioned liquid that extends along the arrangement direction of the plurality of aforementioned pressure chambers and is respectively communicated with the plurality of aforementioned pressure chambers. Adjust the aforementioned calorific value based on the aforementioned heating pulse so as to reduce the gradient in the heat distribution among the plurality of aforementioned pressure chambers along the aforementioned common flow path. (8) The liquid ejection head according to the above (7), wherein Adjust the aforementioned calorific value based on the aforementioned heating pulse so that the aforementioned calorific value gradually increases from the downstream side to the upstream side of the aforementioned liquid in the aforementioned common flow path. (9) The liquid ejection head according to the above (7) or (8), wherein The aforementioned ejection unit further has: A liquid supply flow path that supplies the aforementioned liquid into the aforementioned pressure chamber; and A liquid recovery flow path that recovers the aforementioned liquid from the aforementioned pressure chamber. (10) A liquid ejection recording apparatus Comprising the liquid ejection head according to any one of the above (1) to (9). Description of reference numerals

[0114] 1... Printer, 10... Frame, 2a, 2b... Conveyor mechanism, 21... Grille roller, 22... Pinch roller, 3(3Y, 3M, 3C, 3K)... Ink tank, 4(4Y, 4M, 4C, 4K)... Inkjet head, 41... Nozzle plate, 411, 412... Nozzle rows, 42... Actuator plate, 420... Tail, 421, 422... Channel rows, 43... Cover plate, 49... Driving unit, 493... Flexible printed circuit board, 50... Ink supply tube, 6... Scanning mechanism, 61a, 61b... Guide rails, 62... Carriage, 63... Driving mechanism, 631a, 631b... Pulleys, 632... Endless belt, 633... Driving motor, 9... Ink, P... Recording paper, d... Conveying direction, Hn, H1, H2... Nozzle holes, Dd... Shallow groove portion, Rin1, Rin2... Supply side common flow path, Rout1, Rout2... Recovery side common flow path, Sin1, Sin2... Supply slits, Sout1, Sout2... Recovery slits, W1, W2... Wall portions, Sd... Driving signal, Vd... Driving voltage, Vda... Individual potential (active potential), Vdc... Common potential (common potential), C1, C2... Channels, C1e, C2e... Discharge channels, C1d, C2d... dummy channels (non-discharge channels), Wd... Driving wall, Ed... Driving electrode, Eda... Individual electrode (active electrode), Edc... Common electrode (common electrode), da... Expansion direction, db... Contraction direction, p1, p2... Pulses, Pj... Discharge pulse, Ph, Ph1, Ph2... Heating pulses, Wj, Wh1, Wh2... Pulse widths, Tp... Printing cycle, Tj... Discharge cycle, Td... Driving cycle, fp... Printing frequency, fj... Discharge frequency, fd... Driving frequency, Vi... Viscosity, Vj... Discharge speed, Vj(ave)... Average discharge speed, ΔVj... Difference value of discharge speed Vj, Np... Number of pulses, Rp... Printing rate, Pr1 to Pr5... Temperature measurement sites, Δh... Heat generation amount, t... Time.

Claims

1. A liquid ejecting head comprising: a jetting portion having a plurality of nozzles for jetting a liquid and a plurality of pressure chambers which are individually communicated with the plurality of nozzles and are respectively filled with the liquid; as well as a driving unit that drives the ejection unit based on a driving signal having a plurality of pulses in a predetermined printing cycle, so that the liquid filled in the pressure chamber is ejected from the nozzle, The plurality of pulses in the drive signal include: one or more discharge pulses having a pulse width within a range for discharging the liquid from the nozzle; as well as One or more heat pulses have a pulse width within a range where the liquid is not ejected from the nozzle and adjust a heat amount generated when the ejection unit is driven.

2. The liquid ejecting head according to claim 1, wherein: One or more first heating pulses are provided as the heating pulses between the ejection pulses defining the printing cycle.

3. The liquid ejecting head according to claim 2, wherein: The printing cycle has a plurality of driving cycles defined by the ejection pulse and the first heating pulse. In at least one drive cycle among the plurality of drive cycles, one or more second heat generation pulses are further provided as the heat generation pulses.

4. The liquid ejecting head according to any one of claims 1 to 3, wherein: The heating amount is adjusted according to the number of the heating pulses included in the printing cycle.

5. The liquid ejecting head according to any one of claims 1 to 3, wherein: The drive signal corresponding to the nozzle in a non-discharge period according to the printing content on the recording medium is set to include the heating pulse.

6. The liquid ejecting head according to any one of claims 1 to 3, wherein: When at least one of the ejection frequency when the liquid is ejected from the nozzle and the printing rate on the recording medium changes, The heat amount generated by the heat pulse is adjusted so as to suppress a variation in a discharge speed of the liquid.

7. The liquid ejecting head according to any one of claims 1 to 3, wherein: The ejection unit further includes a common flow path for the liquid extending along the arrangement direction of the plurality of pressure chambers and communicating with the plurality of pressure chambers respectively. The heat amount based on the heat pulse is adjusted so that a gradient in heat distribution between the plurality of pressure chambers along the common flow path is reduced.

8. The liquid ejecting head according to claim 7, wherein: The heat amount generated by the heat pulse is adjusted so that the heat amount gradually increases from the downstream side toward the upstream side of the liquid in the common flow path.

9. The liquid ejecting head according to claim 7, wherein: The injection unit also has: a liquid supply flow path that supplies the liquid into the pressure chamber; and A liquid recovery flow path recovers the liquid from the pressure chamber. 10 . A liquid jet recording apparatus comprising the liquid jet head according to claim 1 .

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