Liquid ejection head

Abstract

A liquid ejector head is provided that can suppress the turbulence of the meniscus shape even when multiple droplets are ejected. It includes a nozzle plate, a pressure chamber, an actuator, and a drive circuit. The nozzle plate has a nozzle for ejecting liquid. The pressure chamber is connected to the nozzle. The actuator changes the volume of the pressure chamber according to a drive signal. The drive circuit generates a drive signal to drive the actuator. The drive signal includes multiple ejection waveforms that eject multiple droplets from the nozzle, and a waveform input midway through the multiple ejection waveforms to suppress residual vibrations caused by ejection waveforms input before this input. The ejection waveform input immediately after the waveform suppressing residual vibrations is timed to reinforce the vibrations generated by the waveform suppressing residual vibrations. The velocity of the droplets ejected by the ejection waveform input immediately after the waveform suppressing residual vibrations is greater than the velocity of the droplets ejected by the ejection waveforms input before the input of the waveform suppressing residual vibrations.

Description

Technical Field

[0001] Embodiments of the present invention relate to liquid ejection heads. Background Technology

[0002] Previously, liquid ejector heads were known to eject droplets of ink and other liquids. By continuously ejecting multiple droplets, the droplet diameter when the droplets fall onto the medium is increased, thus achieving the representation of varying ink density on the medium.

[0003] However, when the sprayed liquid is of low viscosity, during the continuous spraying of multiple droplets, droplets may not be sprayed due to the disordered shape of the curved surface and the entrapment of air bubbles, which becomes the main reason for the deterioration of the printing quality.

[0004] Furthermore, when there is a deviation in the main acoustic vibration period of multiple pressure chambers, if the same driving waveform (the driving waveforms of the first drop and the last drop have different ejection waveform widths) is input to multiple pressure chambers and multiple droplets are ejected continuously, the continuously ejected droplets will not merge, which will become the cause of the deterioration of the printing quality.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Patent No. 6820704 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] The purpose of this invention is to provide a liquid ejector head that can suppress the disorder of the shape of the curved surface even when multiple droplets are ejected.

[0010] Solution for solving the problem

[0011] The liquid ejector head according to the embodiment includes a nozzle plate, a pressure chamber, an actuator, and a drive circuit. The nozzle plate has a nozzle for ejecting liquid. The pressure chamber is in communication with the nozzle. The actuator makes the volume of the pressure chamber variable according to a drive signal. The drive circuit generates a drive signal to drive the actuator. The drive signal includes multiple ejection waveforms that eject multiple droplets from the nozzle, and a waveform input midway through the multiple ejection waveforms to suppress residual vibrations caused by ejection waveforms input before this input. The ejection waveform input immediately after the waveform that suppresses the residual vibrations is input at a timing that reinforces the vibrations generated by the waveform that suppresses the residual vibrations. The velocity of the droplets ejected by the ejection waveform input immediately after the waveform that suppresses the residual vibrations is greater than the velocity of the droplets ejected by the ejection waveforms before the input of the waveform that suppresses the residual vibrations. Attached Figure Description

[0012] Figure 1 This is a cross-sectional view showing the liquid nozzle configuration according to the embodiment with a portion omitted.

[0013] Figure 2 This is a cross-sectional view showing the liquid nozzle configuration according to the embodiment with a portion omitted.

[0014] Figure 3 This is a block diagram schematically illustrating the configuration of the drive circuit of the liquid ejector head according to the embodiment.

[0015] Figure 4 This is a block diagram illustrating an example of the configuration of a liquid ejection device according to an embodiment.

[0016] Figure 5 This is an explanatory diagram showing an example of a driving waveform of the liquid ejector head according to the embodiment, including the ejection waveform of ejecting three droplets and the boost waveform.

[0017] Figure 6 This is an explanatory diagram showing an example of a driving waveform of the liquid ejector head according to the embodiment, including the ejection waveform of ejecting three droplets and the boost waveform.

[0018] Figure 7 This is an explanatory diagram showing an example of a driving waveform of the liquid ejector head according to the embodiment, including an ejection waveform of ejecting two droplets, a boost waveform, and a cancel waveform.

[0019] Figure 8 This is an explanatory diagram showing an example of a driving waveform of the liquid ejector head according to the embodiment, including an ejection waveform of ejecting two droplets, a boost waveform, and a cancel waveform.

[0020] Figure 9 This is an explanatory diagram showing an example of a driving waveform of a liquid ejector head according to an embodiment, including an ejection waveform of ejecting one droplet and a cancellation waveform.

[0021] Figure 10 This is an explanatory diagram showing an example of a driving waveform of the liquid ejector head according to the embodiment, including the ejection waveform of ejecting three droplets and the boost waveform.

[0022] Figure 11 This is an explanatory diagram showing an example of a driving waveform of the liquid ejector head according to the embodiment, including an ejection waveform of ejecting two droplets, a boost waveform, and a cancel waveform.

[0023] Figure 12This is an explanatory diagram showing an example of a driving waveform of a liquid ejector head according to an embodiment, including an ejection waveform of ejecting one droplet and a cancellation waveform.

[0024] Figure 13 This is an illustrative diagram showing an example of the relationship between the waveform width of the ejection waveform and the boost waveform and the amplitude of the pressure vibration generated in the pressure chamber.

[0025] Figure 14 This is an illustrative diagram showing an example of the relationship between the waveform width of the ejection waveform and the boost waveform and the amplitude of the pressure vibration generated in the pressure chamber.

[0026] Figure 15 This is an illustrative diagram showing an example of the relationship between the waveform width of the ejection waveform and the boost waveform and the amplitude of the pressure vibration generated in the pressure chamber.

[0027] Figure 16 This is an illustrative diagram showing an example of the relationship between the waveform width of the ejection waveform and the boost waveform and the amplitude of the pressure vibration generated in the pressure chamber.

[0028] Figure 17 This is an illustrative diagram showing an example of the drive waveform and acoustic vibration of the liquid ejector head according to the embodiment. Detailed Implementation

[0029] The following is for reference Figures 1 to 4 The configuration of the liquid ejector head 1 according to the embodiment will be explained. Figure 1 This is a cross-sectional view showing the liquid ejector head 1 according to the embodiment with a portion of its structure omitted. Figure 2 This is a cross-sectional view showing the liquid ejector head 1 with a portion of its structure omitted. Figure 3 This is a block diagram schematically showing the configuration of the drive circuit 70 of the liquid ejector head 1. Figure 4 This is a block diagram showing an example of the configuration of the liquid ejection device 100. Furthermore, the configuration is shown in appropriate enlargements, reductions, or omissions for the purpose of illustration in the various figures.

[0030] The liquid ejector head 1 involved in this embodiment is, for example, an inkjet head that ejects ink as a liquid. Figure 1 and Figure 2 As shown, the liquid ejector head 1 includes a base 10, an actuator 20, a vibrating plate 30, a flow path plate 40, a nozzle plate 50 having multiple nozzles 51, and a drive circuit 70.

[0031] The base 10 is formed, for example, in the shape of a rectangular plate. The actuator 20 is engaged in the base 10.

[0032] The actuator 20 is, for example, a piezoelectric member having a plurality of piezoelectric pillars 21 and non-driven piezoelectric pillars 22 arranged alternately with the plurality of piezoelectric pillars 21. The actuator 20 is formed in a comb-like shape by arranging the plurality of piezoelectric pillars 21 and the plurality of non-driven piezoelectric pillars 22 at predetermined intervals in one direction. For example, in such an actuator 20, grooves are machined from the end face of the stacked piezoelectric member that is joined to the base 10 by cutting, and a plurality of piezoelectric elements formed in a rectangular columnar shape are formed at predetermined intervals relative to one piezoelectric member. Then, the plurality of piezoelectric elements formed are configured as a plurality of piezoelectric pillars 21 and a plurality of non-driven piezoelectric pillars 22 arranged alternately as piezoelectric elements by setting electrodes or the like. That is, the actuator 20 divides one end side (vibrating plate 30 side) into a plurality of sections by the plurality of grooves formed, and connects the other end side (base 10 side).

[0033] For example, the laminated piezoelectric component constituting actuator 20 is formed by laminating and sintering sheet-like piezoelectric materials. As a specific example, such as... Figure 1 and Figure 2 As shown, the piezoelectric pillar 21 and the non-driven piezoelectric pillar 22 are, for example, stacked piezoelectric elements serving as driving elements. The piezoelectric pillar 21 and the non-driven piezoelectric pillar 22 include multiple stacked piezoelectric layers, multiple internal electrodes formed on the main surface of each piezoelectric layer, and multiple external electrodes. Furthermore, as an example, the piezoelectric pillar 21 and the non-driven piezoelectric pillar 22 have the same configuration.

[0034] The piezoelectric layer is formed into a thin plate shape, for example, from a PZT (lead zirconate titanate) based material or a lead-free KNN (sodium potassium niobate) based material. Multiple piezoelectric layers are bonded together by stacking them in the thickness direction and then sintering them. Furthermore, the stacking direction of the multiple piezoelectric layers is orthogonal to the arrangement direction of the multiple piezoelectric pillars 21 and the multiple non-driven piezoelectric pillars 22.

[0035] The internal electrodes are conductive films of a predetermined shape, made of conductive materials such as silver and palladium that can be sintered. The internal electrodes are formed in predetermined regions on the main surface of each piezoelectric layer. Multiple internal electrodes are arranged alternately in a staggered manner to form different poles.

[0036] External electrodes are formed on the surfaces of multiple piezoelectric pillars 21 and multiple non-driven piezoelectric pillars 22, and are constructed by converging the ends of the internal electrodes. The external electrodes are formed from Ni, Cr, Au, or other materials using known methods such as electroplating or sputtering. The multiple external electrodes are respectively disposed on different side portions of the multiple piezoelectric pillars 21 and multiple non-driven piezoelectric pillars 22, constituting different electrodes. Furthermore, external electrodes of different electrodes can also be arranged in different regions of the same side portion of the multiple piezoelectric pillars 21 and multiple non-driven piezoelectric pillars 22.

[0037] In this embodiment, as an example, the plurality of external electrodes have: individual electrodes formed on each of the plurality of piezoelectric pillars 21 and the plurality of non-driven piezoelectric pillars 22; and a common electrode formed continuously with the plurality of piezoelectric pillars 21 and the plurality of non-driven piezoelectric pillars 22. The plurality of individual electrodes formed on each of the plurality of piezoelectric pillars 21 and the plurality of non-driven piezoelectric pillars 22 are arranged independently of each other. The common electrode is grounded, for example.

[0038] These external electrodes are connected to the drive circuit 70, for example. For example, each external electrode is connected to the control unit 150, which is the drive unit, via wiring and the driver 723 described later in the drive circuit 70, and is configured to be driven and controlled by the processor 151.

[0039] The piezoelectric column 21 and the non-driven piezoelectric column 22 vibrate longitudinally along the stacking direction of the piezoelectric layers by applying a voltage to the internal electrodes via the external electrodes. The longitudinal vibration referred to here means, for example, "vibration in the thickness direction as defined by the piezoelectric constant d33". For example, as... Figure 2 As shown, multiple piezoelectric columns 21, arranged every other one, sandwich a vibrating plate 30 and are correspondingly arranged with the pressure chamber 46, while the remaining non-driven piezoelectric columns 22, sandwiching the vibrating plate 30, are arranged in a position opposite to the partition wall 42.

[0040] The piezoelectric column 21 vibrates longitudinally when a voltage is applied, causing the vibrating plate 30 to displace. That is, the piezoelectric column 21 deforms the pressure chamber 46. The non-driven piezoelectric column 22 is positioned opposite the partition wall 42. No voltage is applied to the non-driven piezoelectric column 22. That is, each piezoelectric column 21 acts as an actuator to deform the pressure chamber 46 by being driven, and each non-driven piezoelectric column 22 forms a support. In other words, the piezoelectric column 21 expands and contracts the pressure chamber 46, making the volume of the pressure chamber variable.

[0041] The vibrating plate 30 is engaged with one side of the piezoelectric layer of the plurality of piezoelectric pillars 21, 22, i.e., the side of the nozzle plate 50. The vibrating plate 30 is deformed, for example, by driving the piezoelectric pillars 21. The vibrating plate 30 is engaged with the piezoelectric pillars 21 and the non-driven piezoelectric pillars 22 of the actuator 20.

[0042] The vibrating plate 30 is, for example, a flat plate arranged in a manner where the thickness direction is the stacking direction of the piezoelectric layers. The surface direction of the vibrating plate 30 extends in the arrangement direction of the plurality of piezoelectric pillars 21 and the plurality of non-driven piezoelectric pillars 22. The vibrating plate 30 is, for example, a metal plate. The vibrating plate 30 has a plurality of vibrating parts 301 that are opposite to each pressure chamber 46 and can be independently displaced. The vibrating plate 30 is formed by integrally connecting the plurality of vibrating parts 301.

[0043] For example, the vibrating plate 30 is configured as a flat plate, and the regions that are connected to the piezoelectric post 21 can be displaced independently. The vibrating plate 30 is, for example, made of SUS plate. The vibrating plate 30 may also have creases or steps formed in the regions adjacent to the vibrating parts 301 or between adjacent vibrating parts 301 to facilitate the displacement of multiple vibrating parts 301.

[0044] The vibrating plate 30 is displaced at the part opposite to the piezoelectric column 21 by the elongation and compression of the piezoelectric column 21 caused by the longitudinal vibration of the piezoelectric column 21, thereby expanding and shrinking the pressure chamber 46 to make the volume of the pressure chamber 46 variable.

[0045] One side of the vibrating plate 30 is engaged with the actuator 20, and the other side is engaged with the flow path plate 40. A pressure chamber 46 for containing ink is formed between the vibrating plate 30 and the flow path plate 40.

[0046] The main surface of one side of the vibrating plate 30 faces the piezoelectric columns 21 and 22 respectively, and the main surface of the other side faces the pressure chamber 46 and the partition wall 42 respectively.

[0047] The flow path plate 40 is joined to the vibrating plate 30. The flow path plate 40 is disposed between the nozzle plate 50 and the vibrating plate 30. The flow path plate 40 has a plurality of partition portions 42. In addition, the flow path plate 40 forms a predetermined flow path 45. The flow path plate 40 forms the plurality of partition portions 42 and the predetermined flow path 45, for example, by stacking a plurality of plates 401 with partial openings.

[0048] The partition wall 42 is arranged in a plurality of directions along which the plurality of piezoelectric columns 21, 22 are arranged, and is positioned opposite the non-driven piezoelectric columns 22 via the vibrating plate 30. The partition wall 42 separates the plurality of pressure chambers 46 of the defined flow path 45 (described later) and the plurality of independent flow paths 47.

[0049] The defined flow path 45 includes: a plurality of pressure chambers 46 separated by partitions 42 of the flow path plate 40; a plurality of independent flow paths 47 separated by partitions 42; and a common flow path 48 connected to the plurality of independent flow paths 47.

[0050] Multiple pressure chambers 46 are arranged in the direction of the arrangement of multiple piezoelectric columns 21 and multiple non-driven piezoelectric columns 22, and are opposed to the multiple piezoelectric columns 21 via a vibrating plate 30. The multiple pressure chambers 46 arranged in one direction are separated by partition walls 42. Multiple partition walls 42 disposed between the multiple pressure chambers 46 are opposed to the multiple non-driven piezoelectric columns 22 via the vibrating plate 30. The multiple pressure chambers 46 are formed by a flow path plate 40 being closed on one side by the vibrating plate 30 and on the other side by a nozzle plate 50 in the piezoelectric layer stacking direction. Furthermore, nozzles 51 formed on the nozzle plate 50 are disposed in the pressure chambers 46.

[0051] Multiple pressure chambers 46 are connected to a common flow path 48 via independent flow paths 47. Each pressure chamber 46 holds liquid supplied from the common flow path 48 through the independent flow paths 47 and is deformed by the vibration of a vibrating plate 30 forming part of the pressure chamber 46, thereby ejecting the liquid from a nozzle 51. Independent flow paths 47 connect the common flow path 48 and the pressure chambers 46. The number of independent flow paths 47 is the same as the number of pressure chambers 46. The cross-sectional shape of the independent flow paths 47 differs from that of the pressure chambers 46. The cross-sectional area of ​​the independent flow paths 47 is smaller than that of the pressure chambers 46. The common flow path 48 is fluidly connected to the multiple independent flow paths 47 and communicates with the pressure chambers 46 through each independent flow path 47.

[0052] The nozzle plate 50 is formed, for example, of a metal such as SUS / Ni or a resin material such as polyimide. The nozzle plate 50 is joined to the flow path plate 40 and covers a plurality of pressure chambers 46. The nozzle plate 50 has a plurality of nozzles 51 formed at positions opposite to the plurality of pressure chambers 46 and extending through in the thickness direction. The plurality of nozzles 51 form a nozzle array.

[0053] like Figure 4 As shown, the drive circuit 70 includes a data buffer 721, a decoder 722, and a driver 723. The data buffer 721 stores the printed data in a time sequence for each piezoelectric post 21, 22. The decoder 722 controls the driver 723 for each piezoelectric post 21, 22 and based on the printed data stored in the data buffer 721. The driver 723 outputs a drive signal that actuates each piezoelectric post 21, 22 based on the control of the decoder 722. The drive signal is the voltage applied to each piezoelectric post 21, 22.

[0054] As a specific example, such as Figure 1 As shown, the driving circuit 70 includes: a wiring film 71, one end of which is connected to an external electrode; a driver IC 72 mounted on the wiring film 71; and a printed wiring substrate mounted on the other end of the wiring film 71. For example, the driver IC 72 includes a data buffer 721, a decoder 722, and a driver 723. Alternatively, the driver IC 72 may have a portion of the data buffer 721, decoder 722, driver 723, and a remaining portion of the printed wiring substrate, etc.

[0055] The drive circuit 70 applies a drive voltage to the external electrode through the driver IC 72, thereby driving the piezoelectric column 21, making the volume of the pressure chamber 46 variable, and causing the droplets to be ejected from the nozzle 51.

[0056] Wiring film 71 is connected to multiple individual electrodes and a common electrode. For example, wiring film 71 is fixed to the connection portion of an external electrode by means of thermoforming or the like. Wiring film 71 is, for example, a COF (Chip on Film) on which a driver IC 72 is mounted.

[0057] The driver IC72 is connected to the external electrode via the wiring film 71. Alternatively, the driver IC72 may be connected to the external electrode via other means such as ACP (anisotropic conductive paste), NCF (non-conductive film), and NCP (non-conductive paste) instead of the wiring film 71.

[0058] The driver IC 72 generates control signals and drive signals applied to each piezoelectric post 21, 22 to actuate the piezoelectric posts 21. Based on the image signal input from the control unit 150 of the liquid ejection device 100, the driver IC 72 generates control signals for timing the selection of ejected ink and controlling the piezoelectric posts 21. Additionally, the driver IC 72 generates a voltage, i.e., a drive signal (electrical signal), applied to the piezoelectric posts 21 according to the control signals. When the driver IC 72 applies a drive signal to the piezoelectric posts 21, the piezoelectric posts 21 displace the vibrating plate 30 and drive the volume of the pressure chamber 46 to expand and contract. This causes pressure vibration in the ink filled into the pressure chamber 46. Through this pressure vibration, ink is ejected from the nozzle 51 disposed in the pressure chamber 46. Furthermore, the liquid ejection head 1 can also be configured to achieve density representation by changing the amount of ink droplets falling onto one pixel. Additionally, the liquid ejection head 1 can also be configured to change the amount of ink droplets falling onto one pixel by changing the number of ink ejections. Thus, the driver IC72 is an example of applying a drive signal to the application part of the piezoelectric column 21.

[0059] Next, as Figure 3 The diagram illustrates an example of a drive circuit 70. The drive circuit 70, for example, includes a voltage control unit 724 and a voltage switching unit 725, the same number as the pressure chambers 46, within the driver IC 72. However, in... Figure 3 The diagram shows two voltage switching units 725; other voltage switching units 725 are omitted.

[0060] The drive circuit 70 is connected to a first voltage source 81, a second voltage source 82, a third voltage source 83, a fourth voltage source 84, and a fifth voltage source 85. The drive circuit 70 provides the voltage supplied from the first voltage source 81 to each wiring electrode 726. Furthermore, the drive circuit 70 selectively provides the voltages supplied from the first voltage source 81, the second voltage source 82, the third voltage source 83, the fourth voltage source 84, and the fifth voltage source 85 to each wiring electrode 727. Here, in the case where the actuator 20 is a stacked PZT, there is a tendency for degradation when applying voltages of two polarities; therefore, the voltages supplied by the first voltage source 81, the second voltage source 82, the third voltage source 83, the fourth voltage source 84, and the fifth voltage source 85 are preferably ground voltage and have one polarity (positive or negative) relative to the ground voltage.

[0061] The output voltage of the first voltage source 81 is, for example, a ground voltage, and its value is set to V0 (V0 > 0 [V] or V0 < 0 [V]). Alternatively, the ground voltage value V0 can also be 0 [V]. The output voltage of the second voltage source 82 is set to V1. Furthermore, V1 is set to a voltage higher than V0. The output voltage of the third voltage source 83 is set to, for example, V2. For example, V2 is set to a voltage higher than V0 and lower than V1. The output voltage of the fourth voltage source 84 is set to V3. Furthermore, V3 is set to a voltage lower than V0. The output voltage of the fifth voltage source 85 is set to, for example, V4. For example, V4 is set to a voltage lower than V0 and higher than V3.

[0062] Wiring electrode 726 is connected to a common electrode that serves as the ground electrode of actuator 20. Multiple wiring electrodes 727 are each connected to an independent electrode that serves as the non-ground electrode of actuator 20.

[0063] The voltage control unit 724 is connected to each of the plurality of voltage switching units 725. The voltage control unit 724 outputs a command indicating which voltage source among the first voltage source 81, the second voltage source 82, and the third voltage source 83 to be selected to each voltage switching unit 725. For example, the voltage control unit 724 receives an image signal from the control unit 150 and determines the switching timing of the voltage sources in each voltage switching unit 725. Then, the voltage control unit 724 outputs a command to the voltage switching unit 725 according to the determined switching timing to select which voltage source among the first voltage source 81, the second voltage source 82, and the third voltage source 83. The voltage switching unit 725 switches the voltage source connected to the wiring electrode 727 according to the command from the voltage control unit 724.

[0064] The voltage switching unit 725 is, for example, composed of a semiconductor switch. The voltage switching unit 725, under the control of the voltage control unit 724, connects any one of the first voltage source 81, the second voltage source 82, the third voltage source 83, the fourth voltage source 84, and the fifth voltage source 85 to the wiring electrode 727. Therefore, the internal electrodes of different poles of the piezoelectric post 21 are connected to the wiring electrode 726 and the wiring electrode 727 via external electrodes (a common electrode and individual electrodes).

[0065] In this drive circuit 70, the drive circuit switches the connection wiring between voltage sources 81-85 and actuator 20 using a switching circuit composed of a voltage control unit 724 and multiple voltage switching units 725, thereby inputting drive waveforms with at least five potential differences as drive signals to the electrode space of actuator 20. Here, the drive waveform includes an ejection waveform that ejects droplets by driving the actuator 20. Furthermore, in this embodiment, potential differences other than the largest and smallest potential differences are referred to as intermediate potential differences. As an example, in Figure 6 , Figure 8 , Figures 10 to 12 The example shown is a driving waveform containing an intermediate potential difference. Furthermore, as described later... Figure 5 , Figure 7 as well as Figure 9 In the example of the driving waveform, since it is a driving waveform that does not include an intermediate potential difference and has three potential differences, there can be three voltage sources. Therefore, in order to input such a driving waveform to the electrodes of the actuator 20, for example, the driving circuit 70 can be configured to connect the first voltage source 81, the second voltage source 82 and the fourth voltage source 84 to the driving circuit 70.

[0066] The printed wiring board is a PWA (Printing Wiring Assembly) that houses various electronic components or connectors. The printed wiring board is connected to the control unit 150 of the liquid ejection device 100.

[0067] Next, refer to Figure 4 An example of a liquid ejection device 100 equipped with a liquid ejection head 1 will be described. The liquid ejection device 100 is, for example, an inkjet recording device. The liquid ejection device 100 is, for example, a liquid ejection device that performs image forming processing on paper by ejecting liquid such as ink while conveying paper, such as paper, as the ejection target medium (i.e., printing medium) from a media supply unit. The liquid ejection device 100 includes, for example, a head unit 130, a control unit 150, a drive motor 161 that drives a paper conveying device, an operation unit 162 that inputs commands from the outside, and various sensors 163.

[0068] The head unit 130 includes: a liquid ejector head 1; an ink tank, which serves as a liquid reservoir, mounted on the liquid ejector head 1; a connecting flow path connecting the liquid ejector head 1 and the ink tank; and a supply pump for supplying ink to the liquid ejector head 1.

[0069] In this embodiment, multiple head units 130 are provided. Each head unit 130 can, for example, use ink of different colors. In each head unit 130, a negative pressure control device such as a pump is connected to the ink tank. Furthermore, the negative pressure control device controls the negative pressure inside the ink tank in a manner corresponding to the head value of the liquid ejector head 1 and the ink tank, thereby forming the ink supplied to each nozzle 51 of the liquid ejector head 1 into a curved surface of a predetermined shape. The supply pump is a liquid delivery pump, such as a piezoelectric pump, and is controlled by the control unit 150.

[0070] The control unit 150 is, for example, a control board. The control unit 150 is equipped with a processor 151, a ROM (Read Only Memory) 152, a RAM (Random Access Memory) 153, an I / O port 154 as an input / output port, and an image memory 155.

[0071] The processor 151 is a processing circuit, including a CPU (Central Processing Unit), which acts as a controller. The processor 151 controls the head unit 130, drive motor 161, operation unit 162, and various sensors 163 installed in the liquid dispensing device 100 via I / O port 154. The processor 151 sends the printed data stored in the image memory 155 to the drive circuit 70 in the order of drawing.

[0072] ROM 152 stores various programs, etc. RAM 153 temporarily stores various variable data or image data, etc. Furthermore, ROM 152 and RAM 153 are examples of storage media; other storage media could be used if they can store various programs or data, etc. I / O port 154 is an interface section for external connection devices such as 200 to input data from and output data to external devices. Printed data from external connection devices 200 is sent to the control unit 150 through I / O port 154 and saved to the image memory 155.

[0073] The characteristics of the liquid nozzle 1 according to the embodiment and the driving waveform (ejection waveform of the driving signal) of the liquid nozzle 1 will be described below. The driving waveform of the liquid nozzle 1 according to the embodiment is composed of a rectangular waveform that includes an expansion potential difference that expands the volume of the pressure chamber 46 and a contraction potential difference that reduces the volume of the pressure chamber 46, and / or a stepped waveform that includes an expansion potential difference, a contraction potential difference, and one or more intermediate potential differences provided between the potential differences.

[0074] Figure 5 One example shown is an explanatory diagram illustrating an example of a driving waveform (3-drop waveform) that includes a rectangular ejection waveform that ejects 3 droplets and a rectangular boost waveform. Figure 6 One example shown is an illustrative diagram illustrating an example of a drive waveform (3-drop waveform) that includes a stepped ejection waveform that ejects three droplets and a rectangular boost waveform.

[0075] Here, a rectangular waveform refers to a waveform that has a decreasing and increasing potential difference with respect to the ground voltage. A stepped waveform refers to a waveform that has a decreasing and increasing potential difference with respect to the ground voltage on the same polarity side with respect to the ground voltage, and that passes through a predetermined time (intermediate voltage time) within the intermediate voltage between the two potential differences. Furthermore, the ejection waveform and the boost waveform have different polarities with respect to the ground voltage. Additionally, the boost waveform refers to a waveform that, by inputting an ejection waveform before the boost waveform input, counteracts the residual vibration at the main acoustic vibration frequency generated in the pressure chamber 46, and increases the amplitude (droplet ejection force) of the pressure vibration in the pressure chamber 46 caused by the ejection waveform input after the boost waveform input.

[0076] Figure 7 One example shown is an illustrative diagram illustrating a driving waveform (2-droplet waveform) comprising a rectangular ejection waveform of two droplets, a rectangular boost waveform, and a rectangular cancellation waveform. Here, the cancellation waveform refers to the waveform that cancels the residual vibrations generated at the main acoustic frequency of the pressure chamber 46 by the ejection waveform of the ejected droplets. Figure 8 This is an illustrative diagram showing an example of a drive waveform (2-droplet waveform) that includes a stepped and rectangular ejection waveform that ejects two droplets, a rectangular boost waveform, and a stepped cancellation waveform.

[0077] Figure 9 This is an illustrative diagram showing an example of a drive waveform (1-drop waveform) that includes a rectangular ejection waveform of one droplet and a rectangular cancellation waveform. Figure 10This is an illustrative diagram showing an example of a drive waveform (3-droplet waveform) that includes a stepped ejection waveform of three droplets and a stepped boost waveform. Figure 11 This is an illustrative diagram showing an example of a drive waveform (2-drop waveform) that includes a stepped ejection waveform that ejects two droplets, a stepped boost waveform, and a stepped cancellation waveform. Figure 12 This is an illustrative diagram showing an example of a drive waveform (1-droplet waveform) comprising a stepped ejection waveform of one droplet and a stepped cancellation waveform. Additionally, in Figure 5 , Figure 6 , Figure 10 In the example of the drive waveform, the cancellation waveform is shown omitting the actual cancellation waveform, but it could also be a drive waveform that includes the cancellation waveform. Furthermore, for example, the waveform width Cp of the cancellation waveform is smaller than AL. Additionally, the waveform width Cp of the cancellation waveform differs from the waveform width Dp of the ejection waveform and the waveform width Bst of the boost waveform.

[0078] Figures 13 to 16 The graph shows the amplitude characteristics of the pressure vibration in pressure chamber 46, with the horizontal axis representing the waveform width and the vertical axis representing the waveform width relative to the condition without residual vibration. It is schematically illustrated with dashed lines. Figures 13 to 16 The diagram schematically illustrates the relationship between the vibrational characteristics of pressure chamber 46 relative to the waveform width and the amplitude of the pressure vibration provided to pressure chamber 46 by the respective waveforms of the ejection waveform with waveform width Dp and the boost waveform with waveform width Bst. Figures 13 to 16 In the following description, avrAL (average AL) is the average AL of multiple pressure chambers 46 with the same input drive waveform. minAL is the minimum AL of multiple pressure chambers 46 with the same input drive waveform. maxAL is the maximum AL of multiple pressure chambers 46 with the same input drive waveform.

[0079] in addition, Figure 13 (a) to (d) show the vibration characteristics of pressure chamber 46 in the half-cycle AL=avrAL of the main acoustic vibration frequency of pressure chamber 46, and respectively show examples where the waveform width Dp of the main acoustic vibration ejection waveform is different from the waveform width Bst of the boost waveform (Dp≠Bst). Figure 14 (a) to (d) show the vibration characteristics of pressure chamber 46 in AL=minAL and AL=maxAL, and show examples where Dp is different from Bst (Dp≠Bst) and Dp has a larger amplitude than Bst. Figure 15 (a) and (b) show the vibration characteristics of pressure chamber 46 in AL=avrAL, and respectively show examples where Dp and Bst are approximately the same (Dp≈Bst). Figure 16(a) to (d) show the vibration characteristics of pressure chamber 46 in AL=minAL and AL=maxAL, and respectively show examples where Dp and Bst are approximately the same (Dp≈Bst).

[0080] Figure 17 This is an illustrative diagram showing an example of the relationship between the stepped ejection waveform of the driving waveform and the main acoustic vibration caused by the rising waveform (3) (4).

[0081] Furthermore, in the driving waveform of this embodiment, examples are described that differentiate between a 1-drop waveform (ejecting one droplet), a 2-drop waveform (ejecting two droplets), and a 3-drop waveform (ejecting three droplets) to represent the density of ink on the medium. The 1-drop waveform is as follows: Figure 9 The waveform shown is a simple injection waveform. Alternatively, a 1-drop waveform can also be set to... Figure 9 Different waveform shapes.

[0082] Next, in an example of the ejection waveform of this embodiment, regarding such... Figure 17 The waveform width of the stepped waveform with intermediate voltage time Tma or Tmb, as shown, is described below. First, consider the composite wave of the two main acoustic vibrations caused by the rising waveforms (3) and (4). Furthermore, in the following description, the half-cycle of the main acoustic vibration frequency of the pressure chamber 46 is set as AL, and the input time of the falling and rising waveforms is set as tin. First, the rising waveform (3) is input according to the timing of tin3, and the pressure chamber 46 is input with a positive pressure of zero phase and amplitude A3. The pressure vibration caused by the rising waveform (3) advances only Tmb in phase at the time point after Tmb. (π / AL). Additionally, the amplitude of the pressure vibration after Tmb is set to A3′. A rising waveform (4) is input at the timing of tin4 after Tmb from tin3, and a positive pressure with zero phase and amplitude A4 is input to pressure chamber 46. The rising waveform (3) at time point tin4 (amplitude A3′ and phase Tmb) is... The composite wave of (π / AL) and the rising waveform (4) (amplitude A4 and phase zero) can be calculated using the formula for the composition of a single vibration. Here, the amplitude of the composite wave of the rising waveform (3) and (4) at time tin4 is set to A(3+4), and the phase of the composite wave is set to (3+4). When the pressure vibration of the rising waveform (3) at time point tin4 is schematically shown, it becomes A3′cos((tin4-tin3)). (π / AL)), when the pressure vibration at time point (4) of tin4 is schematically shown, becomes A4cos((tin4-tin4)). (π / AL) = A4cos0 = A4.

[0083] Therefore, the tin4 time point (3+4) becomes (3+4)=arctan((A3′sin((tin4-tin3)) (π / AL))+A4sin0) / (A3′cos((tin4-tin3) (π / AL) + A4cos0)). When the phase in the main acoustic vibration When the quantity (3+4) is converted into time, it becomes (3+4) AL / π. Here, the observation time point of the composite wave of the rising waveforms (3) and (4) is set to t0(3+4) and it is assumed that the composite wave of the rising waveforms (3) and (4) before tin4 is the composite wave.

[0084] The observation time point t0(3+4) at which the phase of the composite wave of the assumed rising waveforms (3) and (4) becomes zero is the time point from which the phase is traced back from tin4. (3+4) time point tin4- (3+4) AL / π.

[0085] Next, consider the composite wave of the two main acoustic vibrations caused by the falling waveforms (1) and (2). At the timing of tin1, the falling waveform (1) is input, and the pressure chamber 46 is input with a phase of -π and an amplitude of A3. In addition, a negative pressure is generated in the pressure chamber 46 by the falling waveform (1), so the phase is set to -π here. The pressure vibration caused by the falling waveform (1) advances only Tma in phase at the time point Tma. (π / AL). In addition, the amplitude of the pressure vibration after Tma is set as A1′.

[0086] The falling waveforms (1) and (2) are the result of negative pressure being applied to pressure chamber 46 at the input time point. Otherwise, they can be considered as composite waves in the same way as the rising waveforms (3) and (4).

[0087] Here, the amplitude of the composite wave of the rising waveforms (1) and (2) at time point tin2 is set to A(1+2), and the phase of the composite wave is set to... (1+2). When the pressure vibration of the rising waveform (1) at time point tin2 is schematically shown, it becomes A1′cos((tin2-tin1)). (π / AL) - π). Additionally, when the pressure vibration of the rising waveform (2) at time point tin2 is schematically shown, it becomes A2cos((tin2-tin2). (π / AL)-π)=A2cos(-π)=-A2.

[0088] Therefore, the tin2 time point (1+2) becomes (1+2)=arctan((A1′sin((tin2-tin1)) (π / AL)-π)+A2sin(-π)) / (A1′cos((tin2-tin1) (π / AL)-π)+A2cos(-π)). Set the observation time point of the composite wave of the falling waveforms (1) and (2) to t0(1+2), and assume that the composite wave of the falling waveforms (1) and (2) before tin2 is the composite wave.

[0089] The phase of the composite wave of the hypothetical descending waveforms (1) and (2) is the observation time point t0(1+2) of -π, which is the phase of the composite wave traced back from tin2. (1+2) time point tin2- (1+2) AL / π.

[0090] Furthermore, when rising or falling waveforms of the same phase as the primary acoustic vibrations generated during input are continuously input, and the time interval between the first and last inputs is shorter than AL, there is only one observation point t0 within the time interval where the phase of the composite wave of the primary acoustic vibrations generated by the continuous inputs is a multiple of π (e.g., -π, 0, +π). Since Tma and Tmb are shorter than 0.5AL, there is only one observation point t0 where the phase of the composite wave of the primary acoustic vibrations generated by the continuous input of rising or falling waveforms is a multiple of π (e.g., -π, 0, +π).

[0091] The waveform width of the ejection waveform or the boost (Bst) waveform described later in this embodiment is defined as the time point from the point in time when the phase of the synthesized wave of the first primary acoustic vibration that is initially input or when the phase of the input is the same as that of the first primary acoustic vibration and is continuously input, is a multiple of π, to the point in time when the phase of the next primary acoustic vibration that is input, or when the phase of the input is different from that of the first primary acoustic vibration and is continuously input, is a multiple of π.

[0092] Specifically, having Figure 17The waveform width of the ejection waveform at such intermediate voltage time Tma or Tmb is: the time interval between the observation time point t0(1+2) where the phase of the composite wave of the falling waveform (1) and (2) is -π, as assumed above, and the observation time point t0(3+4) where the phase of the composite wave of the rising waveform (3) and (4) is zero, i.e., Dp.

[0093] also, Figure 10 The waveform width of the Bst waveform in such a 3-drop waveform is: the time interval between the observation point t0(b31+b32) where the phase of the composite wave of the rising waveform (b31) and (b32) is zero, and the observation point t0(b33+b34) where the phase of the composite wave of the falling waveform (b33) and (b34) is -π, i.e., Bst33.

[0094] In addition, Figure 17 In the case where the amplitude at time tin4 is A3′≈A4, the observation time point at which the phase of the composite wave of the assumed rising waveforms (3) and (4) becomes zero is the midpoint between tin3 and tin4. Similarly, for the falling waveforms (1) and (2), where the amplitude at time tin2 is A1′≈A2, the observation time point at which the phase of the composite wave of the assumed falling waveforms (1) and (2) becomes -π is the midpoint between tin1 and tin2. For example, when the voltage levels of the falling waveforms (1) and (2) are the same, the flow resistance of the pressure chamber, etc. is small, or the time interval between the falling waveforms (1) and (2) is smaller than the period of the main acoustic vibration, the amplitude A1′≈A2 can be considered. Similarly, when the voltage levels of the rising waveforms (3) and (4) are the same, the flow resistance of the pressure chamber, etc. is small, or the time interval between the rising waveforms (3) and (4) is smaller than the period of the main acoustic vibration, the amplitude A3′≈A4 can be considered.

[0095] Furthermore, when the voltage heights of the rising waveforms (3) and (4) are the same and the flow resistance of the pressure chamber is large, the amplitude becomes A3′<A4 at time tin4, and the observation time point at which the phase of the composite wave of the assumed rising waveforms (3) and (4) becomes zero moves from the midpoint of tin3 and tin4 towards tin4. Similarly, when the voltage heights of the falling waveforms (1) and (2) are the same and the flow resistance of the pressure chamber is large, the amplitude becomes A1′<A2 at time tin2, and the observation time point at which the phase of the assumed falling waveforms (1) and (2) becomes -π moves from the midpoint of tin1 and tin2 towards tin2.

[0096] Therefore, it can be assumed that the time interval between the observation time point t0(1+2) where the phase of the composite wave of the hypothetical falling waveform (1) and (2) becomes -π and the observation time point t0(3+4) where the phase of the composite wave of the hypothetical rising waveform (3) and (4) becomes zero is equivalent to the time interval from the midpoint of tin1 and tin2 to the midpoint of tin3 and tin4.

[0097] Furthermore, the smaller the intermediate voltage time Tma or Tmb, the larger the amplitude of the synthesized wave described above. Additionally, when Tmb is zero, it can be considered equivalent to inputting a stepped waveform with a rise time tr equal to the sum of the voltage heights of rising waveforms (3) and (4) once. Similarly, when Tma is zero, it can also be considered equivalent to inputting a stepped waveform with a fall time tf equal to the sum of the voltage heights of falling waveforms (1) and (2) once.

[0098] For example, it can be considered that Figure 10 The waveform shape when the time difference between the rising waveform (b31) and (b32) is zero, the time difference between the falling waveform (b33) and (b34) is zero, the time difference between the falling waveform (31) and (32) is zero, and the time difference between the rising waveform (33) and (34) is zero becomes Figure 6 That way.

[0099] Similarly, Figure 11 The waveform shape when the time difference between the rising waveform (b21) and (b22) is zero, the time difference between the falling waveform (b23) and (b24) is zero, the time difference between the falling waveform (21) and (22) is zero, and the time difference between the rising waveform (23) and (24) is zero can be considered as Figure 8 That way.

[0100] Furthermore, when multiple drops are continuously ejected to improve printing quality, it is preferable to merge the continuously ejected droplets. Additionally, it is preferable that the speeds of the droplets ejected in 1-drop, 2-drop, and 3-drop waveforms, or the combined speeds, are approximately the same.

[0101] Furthermore, when the liquid ejector head 1 is driven at a high frequency to increase printing speed, the waveform length of the 3-drop waveform is usually longer than that of the 2-drop waveform. Therefore, the limitations on adjusting the speed of each droplet are usually more stringent for the 3-drop waveform. Thus, the waveform adjustment order for the 3-drop waveform is recorded first, followed by the waveform adjustment order for the 2-drop waveform.

[0102] In addition, such as Figure 5 , Figure 6 as well as Figure 10 As shown, the 3-drop waveform becomes the waveform of the initial input 2-stage ejection waveform. First, Figure 5The three droplet waveforms eject the first droplet with a width of Dp31 and the second droplet with a width of Dp32. At this time, Dp31 = Dp32, and the center-to-center distance between the ejection waveforms of Dp31 and Dp32 is 2UL = 2AL. In addition, the half-cycle AL of the main acoustic vibration frequency of the multiple pressure chambers 46 is different due to manufacturing deviation. Here, the maximum value of the half-cycle AL of the main acoustic vibration frequency of the multiple pressure chambers 46 is set as maxAL, and the minimum value is set as minAL. In this case, the value when 1.5AL is the maximum in the multiple pressure chambers 46 is 1.5maxAL, and the value when 2.5AL is the minimum is 2.5minAL. Therefore, it is sufficient to set 2UL, where 1.5AL≤1.5maxAL<2UL<2.5minAL≤2.5AL, as the time difference (center-to-center distance) between the center (0) and (0)′′ of the waveform.

[0103] That is, the interval 2UL between the consecutive ejection waveforms input after the second drop ejection waveform and before the input waveform of width Bst33 (boost waveform) coincides with the period of amplification of the residual vibration of the liquid in pressure chamber 46 generated by the first drop ejection waveform and the vibration of the liquid in pressure chamber 46 generated by the subsequent second drop ejection waveform. Furthermore, the center of the waveform refers to, for example, the center of the waveform width (time) from the input of the descending or ascending waveform to the input of the ascending or descending waveform in each waveform, such as the ejection waveform and the boost waveform; the distance between the centers of the waveforms refers to the time between the centers of adjacent waveforms.

[0104] Furthermore, the residual vibrations generated in the pressure chamber 46 by the input of a waveform of width Bst33 (boost waveform) following the ejection waveform of the second drop are canceled out by the input of the boost waveform to the previous ejection waveform. Here, the boost waveform has a different polarity relative to the ejection waveform and the ground voltage. For example, Dp31, Dp32, and Dp33 expand and contract with voltages lower than the reference ground voltage, and Bst33 contracts and expands with voltages higher than the ground voltage. Thus, the disturbance of the meniscus shape caused by the residual vibrations generated by the ejection waveforms of the first and second drops is suppressed, and air bubbles are prevented from being entrained. Moreover, the ejection waveform of width Dp33 is input immediately after the waveform of width Bst33, and the third drop is ejected. Here, Dp33 = Dp31.

[0105] Furthermore, in order to use a waveform of width Bst33 to counteract the residual vibrations generated by the ejection waveform of width Dp32, Figure 5 The time interval 2UL between the center (0)′′ and (0)b of the waveform is preferably (k-1 / 6)2AL to (k+1 / 6)2AL, and more preferably k 2AL. Furthermore, when AL is scattered from minAL to maxAL, the time interval between the center (0)′′ and (0)b is preferably from (k-1 / 6)2. maxAL to (k+1 / 6)2 minAL. Furthermore, k is a natural number.

[0106] In addition, in order to increase the ejection force of the ejection waveform with a width of Bst33 (i.e., the amplitude of the pressure vibration of the pressure chamber 46 caused by the ejection waveform). Figure 5 The time interval between (0)b and (0)′′′ is preferably (k / 2-1 / 4)2AL to (k / 2+1 / 4)2AL, and more preferably k AL. Furthermore, when AL is scattered from minAL to maxAL, the time interval between (0)b and (0)′′′ is preferably from (k / 2-1 / 4)2. maxAL to (k / 2 + 1 / 4)2 minAL. Furthermore, k is an odd number greater than 1. And in order to increase the ejection force of the ejection waveform with a width of Dp33 using a waveform with a width of Bst33, Figure 5 The time interval between (0)b and (0)′′′ is preferably short, and k=1 is more suitable.

[0107] exist Figure 7 In the two-drop waveform, the first drop is ejected using a Dp21-width ejection waveform, and a Bst22-width waveform (boost waveform) is used to counteract the residual vibration generated in the pressure chamber 46 by the previous ejection before the Bst22-width waveform input. This suppresses turbulence in the meniscus shape and prevents air bubble entrainment. Then, immediately following the Bst22-width waveform, a Dp22-width ejection waveform is input to eject the second drop.

[0108] Furthermore, in order to use a waveform of width Bst22 to counteract the residual vibrations generated by the ejection waveform of width Dp21, Figure 7 The time interval between (0) and (0)b is preferably from (k-1 / 6)2AL to (k+1 / 6)2AL, and more preferably k 2AL. Furthermore, when AL is scattered from minAL to maxAL, the time interval between (0) and (0)b is preferably from (k-1 / 6)2. maxAL to (k+1 / 6)2 minAL. Furthermore, k is a natural number.

[0109] In addition, in order to increase the ejection force of the ejection waveform with a width of Dp22 using a waveform with a width of Bst22, Figure 7the time interval between (0)b and (0)'' is preferably from (k / 2-1 / 4)2AL to (k / 2+1 / 4)2AL, more preferably k AL. In addition, when AL is scattered from minAL to maxAL, the time interval between (0)b and (0)'' is preferably from (k / 2-1 / 4)2 maxAL to (k / 2+1 / 4)2 minAL. Furthermore, k is an odd number of 1 or greater. Moreover, in order to increase the ejection force of the ejection waveform of Dp22 width using the waveform of Bst22 width, Figure 7 the time interval between (0)b and (0)'' is preferably short, and k=1 is more suitable.

[0110] Next, consider the case where the ejection waveform width Dp21 of the first droplet in the two-droplet waveform is different from the waveform width of the Bst width. Figures 13 to 16 it schematically shows the relationship between the vibration characteristics of the waveform width relative to the pressure chamber, the waveform widths of Dp21 and Bst22, and the amplitude of pressure vibration applied to the pressure chamber by each waveform. The amplitude of the pressure vibration applied to the pressure chamber by each waveform varies not only according to the waveform width, but also according to the voltage height of each waveform, rise time such as tf or tr, and intermediate voltage time such as Tma or Tmb. However, in Figures 13 to 16 , it schematically shows the change in amplitude of pressure vibration applied to the pressure chamber 46 caused mainly by the difference between the ejection waveform width Dp21 of the first droplet and the waveform width Bst22 of the Bst width, under the condition that the voltage height of each waveform is set to be the same, and the rise time such as tf or tr and the intermediate voltage time such as Tma or Tmb are also set to be smaller than AL.

[0111] For example, in Figure 14 as shown in (c), when Dp21 is average AL (avrAL) and Bst22 is a waveform smaller than average AL (Dp21=avrAL, Bst22<avrAL), driving a pressure chamber 46 whose half period of main acoustic vibration is maxAL, the decrease in the amplitude of pressure vibration of Bst22 is larger than that caused by Dp21, and there is a concern that the residual vibration generated by Dp21 cannot be completely canceled by Bst22. In this case, the residual vibration caused by Dp21 weakens the ejection force of Dp22 in accordance with the timing when Dp22 is input, so affected by Dp21, the ejection force of the droplet based on Dp22 becomes insufficient, and the ejection speed of the second droplet may be lower than the ejection speed of the first droplet.

[0112] In addition, in Figure 14As shown in (a), when the pressure chamber 46 with a half main acoustic vibration period of minAL is driven by the waveform of Dp21 < avrAL and Bst22 = avrAL (Dp21<avrAL, Bst22=avrAL), the amplitude of pressure vibration caused by Dp21 increases, while on the other hand, the amplitude of pressure vibration caused by Bst22 decreases. Therefore, there is a concern that the residual vibration generated by Dp21 cannot be completely canceled by Bst22. In this case, the residual vibration caused by Dp21 weakens the ejection force of Dp22 according to the timing of input Dp22, so that the ejection force of the droplet based on Dp22 affected by Dp21 becomes insufficient, and the ejection speed of the second droplet may be lower than that of the first droplet.

[0113] Although the above description relates to the waveform widths of Dp21 and Bst22 in the two-droplet waveform, the same concern also arises for the waveform widths of Dp32 and Bst33 in the three-droplet waveform according to the liquid viscosity in the pressure chamber or the flow path resistance of the head.

[0114] Next, consider the situation where the ejection waveform width Dp21 of the first droplet is equal to the Bst width waveform width Bst22 in the two-droplet waveform. For example, as shown in Figure 16 (c), when the pressure chamber with a half main acoustic vibration period of maxAL is driven by the waveform where Dp21 = Bst22, the amplitude decrease of the pressure vibration caused by Dp21 is at the same level as the amplitude decrease of the pressure vibration caused by Bst22.

[0115] Here, when tr or tf of Bst22 is smaller than tf or tr of Dp21, the pressure vibration generated by Bst22 is larger than the pressure vibration generated by Dp21, so the residual vibration of Dp21 is canceled. In addition, when the Bst voltage level of Bst22 is higher than the ejection voltage level of Dp21, the pressure vibration generated by Bst22 is larger than the pressure vibration generated by Dp21, and the residual vibration of Dp21 is canceled.

[0116] In addition, when the intermediate voltage time of Bst22 is shorter than the intermediate voltage time Tm21a or Tm21b of Dp21, the pressure vibration generated by Bst22 is larger than the pressure vibration generated by Dp21, and the residual vibration of Dp21 is canceled. As described above, when the pressure vibration generated by Bst22 is larger than the pressure vibration generated by Dp21, the residual vibration generated by Bst22 strengthens the pressure vibration of the ejection waveform Dp22 input after the time BD22.

[0117] Furthermore, when the velocity of the droplet ejected by the drive waveform consisting solely of the ejection waveform of the Dp22 unit is lower than the ejection velocity of the second droplet ejected by the ejection waveform of the Dp22 unit with a 2-droplet waveform, it can be assumed that the pressure vibration generated by the corresponding 2-droplet waveform Bst22 is greater than the residual vibration generated by Dp21. The residual vibration generated after Bst22 will amplify the pressure vibration of the ejection waveform Dp22 input after the time BD22. Additionally, the waveform width or ejection voltage height tf, tr, intermediate voltage time, etc., of the ejection waveform of the Dp22 unit are equivalent to the following values ​​relative to the 1-droplet waveform in terms of ejection force. In this case, if the droplets ejected through Dp22 or the combined droplets ejected through Dp21 and Dp22 have the same velocity as the droplets ejected through the 1-drop waveform, it can be assumed that the pressure vibration generated by Bst22 is greater than the residual vibration generated by Dp21. The residual vibration generated after Bst22 will strengthen the pressure vibration of the ejection waveform Dp22 input after the time of BD22.

[0118] Here, when a pressure chamber with a main acoustic vibration half-cycle of maxAL is driven by a waveform whose waveform width of Dp22 is smaller than that of Dp21 or Bst22, the decrease in amplitude of the pressure vibration caused by Dp22 is greater than the decrease in amplitude of the pressure vibration caused by Dp21 or Bst22, and the ejection velocity of the second drop may be smaller than that of the first drop. Therefore, it is more preferable to set Dp22=Dp21=Bst22.

[0119] Thus, the decrease in amplitude of the pressure vibration caused by Dp22 becomes the same as the decrease in amplitude of the pressure vibration caused by Dp21 or Bst22, and in the driving of the pressure chamber 46 with a half-cycle of the main acoustic vibration of maxAL, the ejection velocity of the second drop can be maintained to be greater than that of the first drop.

[0120] In the driving of pressure chamber 46, where the half-cycle of the main acoustic vibration is minAL, Dp21 is also set to Bst22. Thus, the decrease in amplitude of the pressure vibration caused by Dp21 becomes the same as the decrease in amplitude of the pressure vibration caused by Bst22, and the residual vibration of Dp21 is canceled out by the pressure vibration of Bst22. Furthermore, if the pressure vibration generated by Bst22 is larger than the pressure vibration generated by Dp21, the residual vibration generated by Bst22 will amplify the pressure vibration of the ejection waveform Dp22 input after time BD22.

[0121] When a pressure chamber with a main acoustic vibration half-cycle of minAL is driven by a waveform whose waveform width of Dp22 is larger than that of Dp21 or Bst22, the amplitude decrease of the pressure vibration caused by Dp22 is greater than the amplitude decrease of the pressure vibration caused by Dp21 or Bst22, and the ejection velocity of the second drop may be smaller than that of the first drop. Therefore, it is more preferable to set Dp22=Dp21=Bst22.

[0122] Furthermore, when droplets are ejected based on Dp22, pressure vibration can be enhanced by Bst22. Therefore, even if the pressure vibration caused by Dp22 is weaker than that caused by Dp21, the ejection velocity of the second droplet is greater than that of the first droplet. However, in order to more reliably maintain the state that the ejection velocity of the second droplet is greater than that of the first droplet, the tr or tf of Dp22 can be made smaller than the tf or tr of Dp21, or the ejection voltage height of Dp22 can be made larger than the ejection voltage height of Dp21, or the intermediate voltage time Tm22a or Tm22b of Dp22 can be made smaller than the intermediate voltage time Tm21a or Tm21b of Dp21.

[0123] Similarly, regarding the waveform widths of Dp31, Dp32, Bst33, and Dp33 of the three-drop waveform, it is preferable to set the waveform widths to Dp31=Dp32=Bst33=Dp33, so that the decrease in amplitude of pressure vibration caused by the change in the half-cycle of the main acoustic vibration is the same in the waveforms of Dp31, Dp32, Bst33, and Dp33.

[0124] Next, consider the ejection velocities of the 2-drop and 1-drop waveforms when the values ​​of Dp22=Dp21=Bst22 are greater than minAL and less than maxAL. Figure 9 or Figure 12 In the pressure vibration of the ejection waveform with only Dp11, the ejection velocity of such a 1-drop waveform needs to be set to be the same as that of the ejection droplet of the 2-drop waveform, so it is set to Dp11 = average AL.

[0125] In a pressure chamber where the dominant acoustic vibration is minAL, the velocity of two droplets ejected with a waveform equal to minAL (Dp22=Dp21=Bst22) may be greater than the velocity of one droplet ejected with a waveform equal to average AL (Dp11=average AL). Similarly, in a pressure chamber where the dominant acoustic vibration is maxAL, the velocity of two droplets ejected with a waveform equal to maxAL (Dp22=Dp21=Bst22) may also be greater than the velocity of one droplet ejected with a waveform equal to average AL (Dp11=average AL). The same concern arises in any of the pressure chambers where the dominant acoustic vibrations are minAL to maxAL, provided that Dp22=Dp21=Bst22 is greater than minAL and less than maxAL.

[0126] Therefore, considering the reduction of the droplet velocity difference between the 2-drop waveform and the 1-drop waveform, it is preferable that the value of Dp22=Dp21=Bst22 is smaller than minAL or larger than maxAL.

[0127] Similarly, in the case of a 3-drop waveform, considering the reduction of the droplet velocity difference between the 3-drop waveform and the 1-drop waveform, the values ​​of Dp31=Dp32=Bst33=Dp33 are preferably smaller than minAL or larger than maxAL.

[0128] Next, in Figure 5 and Figure 7 The example illustrates specific examples of adjusting the waveform width or ejection voltage height and Bst voltage height for 3-drop and 2-drop waveforms. First, the head is driven with a 1-drop waveform, and the ejection speed is measured relative to the voltage change of the falling waveforms (1) and (2). The voltage change (e.g., 14V) of the falling waveforms (1) and (2) that will become the desired ejection speed (e.g., 7 m / s) is set as the ejection voltage height, and then the 3-drop and 2-drop waveforms are adjusted with the same ejection voltage height.

[0129] Next, the waveform width of Dp31 (=Dp32=Bst33=Dp33) of the 3-drop waveform is tentatively set in the range of 0.5AL to 1AL. Here, 0.75AL is set as the waveform width of Dp31 (=Dp32=Bst33=Dp33). Here, the Bst voltage height is tentatively set to the same voltage as the ejection voltage height, and the relationship between the ejection velocity of each droplet ejected through the 3-drop waveform and the Bst voltage height is measured. Here, the Bst voltage height for the third drop, which has a greater ejection velocity than the first or second drop, is studied in the 3-drop waveform, and this voltage is set as the Bst voltage height (e.g., 14V).

[0130] Next, the relationship between the ejection velocity of each droplet ejected by the 3-drop waveform and the waveform width of Dp31 (=Dp32=Bst33=Dp33) is determined. Here, the waveform width of Dp31 (=Dp32=Bst33=Dp33) is studied, where the ejection velocity of any one of the first, second, or third drops of the 3-drop waveform, or the combined ejection velocity of the first, second, and third drops, is approximately the same as the velocity of a droplet ejected with a 1-drop waveform (e.g., 7 m / s). This waveform width is set as the waveform width of Dp31 (=Dp32=Bst33=Dp33) of the 3-drop waveform (e.g., 0.65AL). With the voltage height and waveform width determined, a cancellation waveform can be added after the ejection waveform of the third drop to suppress residual vibrations remaining in the pressure chamber after the third drop.

[0131] Next, in Figure 7 In the example, the adjustment of the 2-drop waveform is described. The ejection voltage height and Bst voltage height of the 2-drop waveform are set to the same voltage heights as those of the 3-drop waveform. First, the relationship between the ejection velocity of each droplet ejected through the 2-drop waveform and the waveform width of Dp21 (=Bst22=Dp22) is measured. Here, the waveform width of Dp21 (=Bst22=Dp22), which is approximately the same as the ejection velocity of either the first or second droplet of the 2-drop waveform, or the ejection velocity of the combined droplet of the first and second drops, and the velocity of the droplet ejected with the 1-drop waveform (e.g., 7 m / s), is studied, and this waveform width is set to the waveform width of Dp21 (=Bst22=Dp22) of the 2-drop waveform (e.g., 0.72AL). At this point, the voltage heights and waveform widths have been determined, so it is only necessary to adjust the cancellation waveform after the ejection waveform of the second drop to suppress the residual vibration remaining in the pressure chamber after the second drop.

[0132] In addition, in Figure 5 When a low-viscosity liquid is ejected in a 3-drop waveform, a large residual vibration occurs after the second droplet is ejected. To counteract this, the Bst voltage height is sometimes increased. Here, an ejection waveform of Dp33 width is input immediately after a Bst33 width waveform, but with a large Bst voltage height, a large negative pressure is generated in the pressure chamber, which may cause air bubble entrainment. In this case, it is sufficient to reduce the residual vibration caused by the ejection waveforms of the first and second drops.

[0133] For example, in the drive circuit 70, a voltage source (e.g., a fifth voltage source 85) having an intermediate voltage with an ejection voltage height is set to the voltage height of the ejection waveforms of the first and second drops. Or, as Figure 6In this way, by setting the ejection waveforms of the first and second drops to a stepped waveform that changes to the next voltage after a fixed waiting time at an intermediate voltage, and adjusting the waiting time, the amplitude of the pressure vibration applied to the pressure chamber 46 can be adjusted by the ejection waveforms of the first and second drops, thereby suppressing residual vibrations after the ejection of the first and second drops. Alternatively, the fall time tf and rise time tr of the ejection waveforms of the first and second drops can be set to be longer than the width of the Bst waveform, or the fall time tf and rise time tr of the ejection waveform of the third drop. Furthermore, for example, when the actuator 20 is a capacitor and the wiring circuit connecting the voltage source and the actuator is considered a CR series circuit, the voltage rise or voltage fall time constant can be changed by changing the resistance R in the circuit wiring. Furthermore, since the waveform width Dp31 of the first drop is set to be approximately the same as the waveform width Dp32 of the second drop, the decrease in the amplitude of the pressure vibration caused by Dp31 in the pressure chamber, which has a different half-cycle from AL, is also the same as that of Dp32. This can suppress the change in the magnitude relationship between the ejection velocities of the first and second drops of the three-drop waveform.

[0134] In the future, if Figure 6 The following is an example illustrating the adjustment of the 3-drop and 2-drop waveforms when the ejection waveforms of the first and second drops are stepped. The 1-drop waveform is set to the same height regardless of the desired ejection velocity (e.g., 7 m / s) or the voltage changes of the falling waveforms (1) and (2) and the rising waveforms (3) and (4) (e.g., 14V). Furthermore, the intermediate voltage times of the 3-drop and 2-drop waveforms are all set to be the same (e.g., Tm31a=Tm31b=Tm32a=Tm32b=Tm21a=Tm21b=0.3AL).

[0135] First, the waveform width of Dp31 (=Dp32=Bst33=Dp33) of the 3-drop waveform is tentatively set in the range of 0.5AL to 1AL. Here, 0.75AL is set as the waveform width of Dp31 (=Dp32=Bst33=Dp33). Here, the Bst voltage height is tentatively set to the same voltage as the ejection voltage height, and the relationship between the ejection velocity of each droplet ejected through the 3-drop waveform and the Bst voltage height is measured. Here, the Bst voltage height where the ejection velocity of the third drop is greater than that of the first or second drop in the 3-drop waveform is investigated, and this voltage is set as the Bst voltage height (e.g., 10.5V).

[0136] Next, the relationship between the ejection velocity of each droplet ejected by the 3-drop waveform and the waveform width of Dp31 (=Dp32=Bst33=Dp33) is determined. Here, the waveform width of Dp31 (=Dp32=Bst33=Dp33) is studied, where the ejection velocity of any one of the first, second, or third drops of the 3-drop waveform, or the combined ejection velocity of the first, second, and third drops, is approximately the same as the velocity of the droplet ejected by the 1-drop waveform (e.g., 7 m / s). This waveform width is set as the waveform width of Dp31 (=Dp32=Bst33=Dp33) of the 3-drop waveform (e.g., 0.75AL). With the voltage height and waveform width determined, a cancellation waveform can be added after the ejection waveform of the third drop to suppress residual vibrations remaining in the pressure chamber after the third drop.

[0137] Next, as Figure 8 The adjustment is recorded in the case where the first drop in the 2-drop waveform is stepped. The ejection voltage height and Bst voltage height of the 2-drop waveform are set to the same voltage heights as those of the 3-drop waveform. First, the relationship between the ejection velocity of each droplet ejected through the 2-drop waveform and the waveform width of Dp21 (=Bst22=Dp22) is measured. Here, the waveform width of Dp21 (=Bst22=Dp22), which is approximately the same as the ejection velocity of either the first or second drop in the 2-drop waveform, or the ejection velocity of the combined droplet of the first and second drops, and the velocity of the droplet ejected with the 1-drop waveform (e.g., 7 m / s), is studied, and this waveform width is set to the waveform width of Dp21 (=Bst22=Dp22) of the 2-drop waveform (e.g., 0.78AL). Since the voltage heights and waveform widths have been determined, it is only necessary to adjust the cancellation waveform after the ejection waveform of the second drop to suppress the residual vibration remaining in the pressure chamber after the second drop.

[0138] In the examples described above, as Figure 6 The waveforms of the three drops show that the first and second drops ejected in a stepped pattern, but it can also be like... Figure 10 The waveform with a width of Bst, like the three-drop waveform, or the ejection waveform of the third drop, can also be set in a stepped shape. However, it is preferable that the intermediate voltage time of the waveform with a width of Bst or the ejection waveform of the third drop is shorter than the intermediate voltage time of the ejection waveforms of the first and second drops, and that the amplitude of the pressure vibration provided to the pressure chamber 46 by the waveform with a width of Bst or the ejection waveform of the third drop is larger than the amplitude of the pressure vibration provided to the pressure chamber 46 by the ejection waveforms of the first and second drops.

[0139] The same applies to the 2-drop waveform. Figure 11Similar to the two-drop waveform, the Bst-width waveform or the ejection waveform of the second drop can also be stepped. However, it is preferable that the intermediate voltage time of the Bst-width waveform or the ejection waveform of the second drop is shorter than the intermediate voltage time of the ejection waveform of the first drop, and that the amplitude of the pressure vibration provided to the pressure chamber 46 by the Bst-width waveform or the ejection waveform of the second drop is larger than the amplitude of the pressure vibration provided to the pressure chamber 46 by the ejection waveform of the first drop.

[0140] Furthermore, when it is desirable to set Dp21, Bst22, and Dp22 to different values ​​in order to fine-tune the droplet velocities of the two droplet waveforms, it is preferable to set Dp21, Bst22, and Dp22 to values ​​as close as possible, so that the pressure of the liquid in the pressure chamber 46 based on Dp21, Bst22, and Dp22 is similar. For example, the time difference between Dp21, Bst22, and Dp22 is preferably the smallest time difference other than zero that can be set in the drive circuit 70 that generates the corresponding drive waveform.

[0141] For example, when the waveform of 2 drops is set to Dp21=Bst22=Dp22=2.34μs and UL=3.0μs, the velocity of the merged droplet formed by the waveform of 2 drops is set to be greater than the velocity of the ejected droplet of the waveform of 1 drop. When the waveform of 3 drops is set to Dp31=Dp32=Dp33=2.32μs and UL=3.0μs, the velocity of the merged droplet formed by the waveform of 2 drops is set to be less than the velocity of the ejected droplet of the waveform of 1 drop.

[0142] In the drive circuit 70 of the corresponding liquid nozzle 1, if it is not possible to set the value of Dp21 or Bst22 to a value between 2.34μs and 2.32μs, for example, it can be set to Dp21=Bst22=2.32μs, Dp22=2.34μs, UL=3.0μs. Alternatively, it can be set to Dp21=2.34μs, Bst22=Dp22=2.32μs, UL=3.0μs.

[0143] Furthermore, when it is desirable to set Dp31, Dp32, Bst33, and Dp33 to different values ​​in order to fine-tune the droplet velocity of the three-drop waveform, it is also preferable to set Dp31, Dp32, Bst33, and Dp33 to values ​​as close as possible, so that the pressure of the liquid in the pressure chamber 46 based on Dp31, Dp32, Bst33, and Dp33 is similar. For example, the time difference between Dp31, Dp32, Bst33, and Dp33 is preferably the smallest time difference other than zero that can be set in the drive circuit 70 that generates the corresponding drive waveform.

[0144] For example, when the 3-drop waveform is set to Dp31=Dp32=Bst33=Dp33=2.26μs and UL=3.0μs, it is assumed that the velocity of the merged droplet formed by the 3-drop waveform is greater than the velocity of the ejected droplet of the 1-drop waveform. When the 3-drop waveform is set to Dp31=Dp32=Bst33=Dp33=2.24μs and UL=3.0μs, it is assumed that the velocity of the merged droplet formed by the 3-drop waveform is less than the velocity of the ejected droplet of the 1-drop waveform.

[0145] In the drive circuit 70 of the corresponding liquid nozzle 1, if it is not possible to set the values ​​of Dp31 or Dp32, Bst33, and Dp33 to values ​​between 2.26μs and 2.24μs, for example, it can be set to Dp31=Dp32=Bst33=2.24μs, Dp33=2.26μs, UL=3.0μs. Alternatively, it can be set to Dp31=Dp32=2.26μs, Bst33=Dp33=2.24μs, UL=3.0μs.

[0146] Next, refer to Figure 11 The conditions for using a waveform of width Bst22 to counteract the residual vibrations generated by an ejection waveform of width Dp21 are explained.

[0147] When the period of the acoustic resonant frequency of the pressure chamber is 2AL, the vibration period generated by the ejection waveform, such as Dp21, which generates positive pressure after negative pressure, is also 2AL. Furthermore, the phase of the composite wave of the negative and positive pressures is -π / 2 at the midpoint between the time points of negative and positive pressure generation. Similarly, in the case of a waveform like Bst22, which generates negative pressure after positive pressure, the phase of the composite wave of the positive and negative pressures is π / 2 at the midpoint between the time points of positive and negative pressure generation. If the distance between the center of the waveform width of Dp21 and the center of the waveform width of Bst22 is set to 2UL, and made consistent with 2AL, the pressure vibrations generated by both weaken each other.

[0148] Furthermore, when the width of Dp21 is the same as the width of Bst22, the time interval between the midpoints of (1) and (2) and the midpoints of (b21) and (b22) also becomes 2UL. Similarly, the time interval between the midpoints of (3) and (4) and the midpoints of (b23) and (b24) also becomes 2UL.

[0149] Here, the amplitude of the composite wave vector Da′′ of the falling waveforms (1) and (2) at the midpoint of time (b21) and (b22) is set to |Da′′|, and the phase is set to Da′′.

[0150] Next, let's assume the composite wave vector Ba′′ of the rising waveforms (b21) and (b22) at the midpoint of time (b21) and (b22), set its amplitude to |Ba′′|, and its phase to... When Ba′′, it becomes

[0151] Da′′=|Da′′|(cos Da′′,sin Da′′), becomes Ba′′=|Ba′′|(cos Ba′′,sin Ba′′).

[0152] Here, we consider the condition that the absolute value of the composite vector of Da′′ and Ba′′ is less than or equal to the larger of the absolute values ​​of Da′′ and Ba′′ (or less than or equal to the larger of the absolute values ​​of Da′′ and Ba′′ if they are the same).

[0153] In this case, the absolute value of the resultant vector of Da′′ and Ba′′ becomes, according to the formula for the composition of a single vibration or the addition theorem. (Mathematical formula 1).

[0154] When |Da′′|≤|Ba′′|, |Ba′′|≥ the phase difference between Da′′ and Ba′′ for which mathematical expression 1 holds. Da′′- Ba′′ becomes the condition that the periodic 2AL oscillations generated by Da′′ and Ba′′ mutually weaken each other. When |Ba′′|≥ the square of both sides of mathematical equation 1 and is transformed, it becomes

[0155] 0≥|Da′′|+2 |Ba′′| cos( Da′′- Ba′′) (Mathematical formula 2).

[0156] Based on the above, if the phase difference between Da′′ and Ba′′ is ( Da′′- If Ba′′ is within the range of 180 degrees ± 60 degrees, then mathematical expression 2 holds true.

[0157] Furthermore, when |Da′′|≥|Ba′′|, by squaring both sides of mathematical expression 1 and transforming it, we get:

[0158] 0≥|Ba′′|+2 |Da′′| cos( Da′′- Ba′′) (Mathematical formula 3).

[0159] Based on the above, if the phase difference between Da′′ and Ba′′ is ( Da′′- If Ba′′ is within the range of 180 degrees ± 60 degrees, then mathematical expression 3 holds true.

[0160] The phases of the pressure vibrations generated by the rising waveforms (b21) and (b22) are both zero. When the amplitudes of (b21) and (b22) are also set to be almost the same, the phases are zero. Ba′′ becomes zero.

[0161] The phase of the pressure vibration generated by the falling waveforms (1) and (2) is -π. When the amplitudes of (1) and (2) are also set to be almost the same, the phase of the composite wave vector of (1) and (2) at the midpoint of (1) and (2) becomes -π. The phase of Da′′ after 2UL time from that point is... Da′′ becomes -π+2UL (π / AL).

[0162] Therefore, the phase difference ( Da′′- Ba′′) becomes the range of 180 degrees ± 60 degrees for 2UL, which becomes the range from (k-1 / 6)2AL to (k+1 / 6)2AL. Furthermore, k is a natural number.

[0163] Furthermore, when considering the use of residual vibrations generated by Bst22 to enhance the pressure vibration of the ejection waveform Dp22 input after the time of BD22, it is preferable that |Da′′|≤|Ba′′|.

[0164] Furthermore, the phase difference between the pressure vibrations generated by the rising waveforms (3) and (4) and the pressure vibrations caused by the falling waveforms (b23) and (b24) is also ±π, and the time interval between the midpoints of (3) and (4) and the midpoints of (b23) and (b24) is also 2UL. If 2UL is set to the range from (k-1 / 6)2AL to (k+1 / 6)2AL, then the pressure vibrations with a 2AL period generated by (3) and (4) and the pressure vibrations with a 2AL period generated by (b23) and (b24) weaken each other. In addition, k is a natural number. Furthermore, the amplitude of the composite wave vector Db′′ of the rising waveforms (3) and (4) at the midpoint time point of (b23) and (b24) is set to |Db′′|, and the amplitude of the composite wave vector Bb′′ of the rising waveforms (b23) and (b24) at the midpoint time point of (b23) and (b24) is set to |Bb′′|. When considering using the residual vibration generated by Bst22 to enhance the pressure vibration of the ejection waveform Dp22 input after the time of BD22, it is preferable that |Db′′|≤|Bb′′|.

[0165] Furthermore, if we consider that the phase of the composite wave of the pressure vibration generated by Dp21 is -π / 2 at the center of the width of Dp21, and the phase of the composite wave of the pressure vibration generated by Bst22 is π / 2 at the center of the width of Bst22, then the phase difference between the two pressure vibrations is also ±π, and the interval between the center of the waveform width of Dp21 and the center of the waveform width of Bst22 is 2UL. If 2UL is set to the range from (k-1 / 6)2AL to (k+1 / 6)2AL, then the pressure vibration with a 2AL period generated by Dp21 and the pressure vibration with a 2AL period generated by Bst22 mutually weaken each other. In addition, when considering using the residual vibration generated by Bst22 to enhance the pressure vibration of the ejection waveform Dp22 input after BD22, it is necessary to make the amplitude of the pressure vibration with a 2AL period generated by Bst22 greater than the amplitude of the pressure vibration with a 2AL period generated by Dp21 at the Bst22 input time point.

[0166] Additionally, regarding using a waveform with a Bst33 width to cancel out the signal... Figure 10The conditions for residual vibration generated by the ejection waveform of width Dp32 are the same. The interval between the center of the Dp32 waveform width and the center of the Bst33 waveform width is 2UL. If 2UL is set to the range from (k-1 / 6)2AL to (k+1 / 6)2AL, the pressure vibration of the 2AL period generated by Dp32 and the pressure vibration of the 2AL period generated by Bst33 will mutually weaken each other. Furthermore, when considering using the residual vibration generated by Bst33 to enhance the pressure vibration of the ejection waveform Dp33 input after time BD33, it is necessary to make the amplitude of the pressure vibration of the 2AL period generated by Bst33 greater than the amplitude of the pressure vibration of the 2AL period generated by Dp32 at the Bst33 input time point.

[0167] As described above, the driving waveform of the liquid ejector head 1 according to the embodiment is configured to eject multiple droplets by setting multiple ejection waveforms. Midway through ejecting all the droplets, a waveform that cancels the residual vibration of the main acoustic vibration is input to suppress the disorder of the meniscus shape, and the remaining droplets are ejected based on this. Specifically, immediately before the last ejection waveform among the multiple droplets, the driving waveform of the liquid ejector head 1 inputs a waveform (boost waveform) that cancels the residual vibration of the main acoustic vibration of one or more ejection waveforms input earlier than the last ejection waveform, suppressing the disorder of the meniscus shape, and the remaining droplets are ejected based on this. Furthermore, immediately after the boost waveform that cancels the residual vibration of the main acoustic vibration, the driving waveform inputs an ejection waveform for ejecting the last droplet at a timing that mutually reinforces the boost waveform that cancels the residual vibration and the vibration within the pressure chamber 46.

[0168] The boost waveform for canceling residual vibration is designed to generate a waveform in the pressure chamber 46 that produces a vibration greater than the residual vibration of the main acoustic vibration generated in the pressure chamber 46 due to the input of the ejection waveform prior to the input of the boost waveform. Thus, the boost waveform for canceling residual vibration functions as a waveform that increases the ejection force of the ejection waveform that is input immediately after the input boost waveform and which performs the ejection of the remaining droplets.

[0169] In other words, existing technologies, as a means of adjusting the intensity of vibration applied to the pressure chamber by ejecting a waveform, a waveform to counteract residual vibration, or a boosted waveform, employ a method of independently adjusting the waveform width by ensuring each droplet reaches a desired speed during continuous ejection, for example, by gradually increasing the speed. However, when there are deviations in the main acoustic vibration periods of multiple pressure chambers, the ratio of the main acoustic vibration period of each pressure chamber to the width of the ejection waveform of each droplet varies for each pressure chamber. Therefore, depending on the different main acoustic vibration periods of the pressure chambers, the continuously ejected droplets may not merge, leading to a deterioration in print quality.

[0170] In this embodiment, the driving waveform of the liquid ejector head 1 is the same as the driving waveform input to multiple pressure chambers 46 and continuously ejecting multiple droplets, with the waveform widths of the ejection waveform and the pressurization waveform being set to be the same. Therefore, even if there is a deviation in the main acoustic vibration period of the multiple pressure chambers 46, it is possible to suppress changes in the magnitude relationship of the velocity of the continuously ejected droplets.

[0171] Furthermore, the magnitude of the vibration generated in the pressure chamber 46 is adjusted by a waveform that cancels out the residual vibration of the main acoustic vibration generated by the input of a mid-stage ejection waveform among multiple ejection waveforms; in other words, by a boosting waveform that increases the ejection force of the ejection waveform that subsequently ejects the remaining droplets among multiple droplets. The magnitude of the vibration generated in the pressure chamber 46 by the boosting waveform is adjusted, for example, by the ratio of the voltage height of the boosting waveform to that of the ejection waveform input before it (before the boosting waveform input). Additionally, the magnitude of the vibration generated in the pressure chamber 46 by the boosting waveform is adjusted, for example, by the difference in the intermediate voltage time between the boosting waveform and the ejection waveform input before the boosting waveform. Furthermore, the magnitude of the vibration generated in the pressure chamber 46 by the boosting waveform is adjusted, for example, by the difference in the rise time and fall time when the voltage of the boosting waveform and the ejection waveform input before the boosting waveform changes.

[0172] Thus, according to the liquid ejector head 1 of the embodiment, in the drive waveform that ejects multiple droplets, a waveform (boost waveform) is input midway through the multiple ejection waveforms. This waveform causes the pressure chamber 46 to generate a vibration larger than the residual vibration caused by the ejection waveforms input up to this point. Furthermore, the ejection force (amplitude) of the ejection waveform input after the waveform that cancels the residual vibration is increased by the waveform that cancels the residual vibration. Therefore, the velocity of the droplets ejected by the ejection waveform immediately following the waveform that suppresses residual vibration (boost waveform) is greater than the velocity of the droplets ejected by the ejection waveforms before the boost waveform input. Thus, by inputting the boost waveform midway through the drive waveform that ejects multiple droplets, the liquid ejector head 1 can suppress the disorder of the meniscus shape even when ejecting multiple droplets. Therefore, even if the viscosity of the ejected liquid is low, the liquid ejector head 1 can suppress the deterioration of printing quality.

[0173] According to at least one embodiment of the liquid ejector described above, by inputting a boosted waveform midway through multiple ejection waveforms, residual vibrations generated by the ejection waveforms can be counteracted, and by increasing the ejection force of the ejection waveform after the boosted waveform, disturbances in the shape of the meniscus can be suppressed even when multiple droplets are ejected.

[0174] While several embodiments of the invention have been described, these embodiments are given by way of example and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments or variations thereof are included in the scope or spirit of the invention and are included within the scope of the invention as set forth in the claims and its equivalents.

[0175] Explanation of reference numerals in the attached figures

[0176] 1…Liquid nozzle, 10…Base, 20…Actuator, 21…Piezoelectric column, 22…Non-driven piezoelectric column, 30…Vibrating plate, 40…Flow path plate, 42…Blocking section, 45…Flow path, 46…Pressure chamber, 47…Independent flow path, 48…Common flow path, 50…Nozzle plate, 51…Nozzle, 70…Driver circuit, 71…Wire diaphragm, 72…Driver IC, 81…First voltage source, 82…Second voltage source, 83…Third voltage source, 84…Fourth voltage source, 85…Fifth voltage source, 1 00…Liquid ejection device, 130…Head unit, 150…Control unit (control board), 151…Processor, 154…I / O port, 155…Image memory, 161…Drive motor, 162…Operating unit, 163…Various sensors, 200…External connection device, 301…Vibration part, 721…Data buffer, 722…Decoder, 723…Driver, 724…Voltage control unit, 725…Voltage switching unit, 726…Wired electrode, 727…Wired electrode.

Claims

1. A liquid ejector head, characterized in that, have: Nozzle plate, equipped with nozzles for spraying liquid; The pressure chamber is connected to the nozzle; An actuator that makes the volume of the pressure chamber variable according to a drive signal; as well as The drive circuit generates the drive signal that drives the actuator. The drive signal includes: Multiple ejection waveforms that cause multiple droplets to be ejected from the nozzle; as well as A waveform input midway through the plurality of ejection waveforms to suppress residual vibrations caused by ejection waveforms input prior to this input. The ejection waveform, which is input immediately after the waveform that suppresses the residual vibration, is input at a timing that reinforces the vibration generated by the waveform that suppresses the residual vibration. The velocity of the droplets ejected by the ejection waveform immediately following the waveform that suppresses the residual vibration is greater than the velocity of the droplets ejected by the ejection waveform preceding the input of the waveform that suppresses the residual vibration.

2. The liquid ejector head according to claim 1, wherein, The waveform width of the waveform that suppresses the residual vibration is approximately the same as the waveform width of the ejection waveform prior to the waveform that suppresses the residual vibration.

3. The liquid ejector head according to claim 1, wherein, The intervals between consecutive ejection waveforms input before the waveform that suppresses the residual vibration are consistent with the period that amplifies the residual vibration of the liquid in the pressure chamber generated by the previously input ejection waveform and the vibration of the liquid in the pressure chamber generated by the subsequent ejection waveform.

4. The liquid ejector head according to claim 1, wherein, The waveform widths of the waveform that suppresses the residual vibration and the waveform width of the ejection waveform are smaller than the minimum value of the half-cycle of the main acoustic vibration of the pressure chamber, or larger than the maximum value of the half-cycle of the main acoustic vibration of the pressure chamber.

5. The liquid ejector head according to claim 1, wherein, The intermediate voltage time of the waveform that suppresses the residual vibration is shorter than the intermediate voltage time of the ejected waveform that was input before the input of the waveform that suppresses the residual vibration.

6. The liquid ejector head according to claim 1, wherein, The rise time and fall time of the waveform that suppresses the residual vibration are smaller than the rise time and fall time of the ejection waveform that was input before the input of the waveform that suppresses the residual vibration.

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