Droplet ejecting apparatus, control method of the same, and program

Abstract

To increase speed and resolution and improve gradation.SOLUTION: A CPU of a printer, in a discharge treatment on the basis of one recording command, controls an actuator from a driver IC to selectively supply a drive signal for middle droplet D2, a drive signal for large droplet D3, and a drive signal for small droplet D1 of which resolution is higher than the resolution of the drive signal for middle droplet and the drive signal for large droplet.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a droplet ejection device that ejects droplets onto a recording medium, a control method thereof, and a program. [Background technology]

[0002] Patent Document 1 shows that in conventional technology, the carriage movement speed is sometimes slowed down to increase the resolution in the carriage movement direction, and that it is necessary to increase the number of movement speeds in order to achieve multiple resolutions. Patent Document 1 also shows that in order to achieve multiple resolutions without increasing the number of movement speeds, the movement speed is made the same and the drive waveform is made different in multiple print modes that perform printing at each resolution with different droplet volumes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-019100 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology in Patent Document 1 eliminates the need to slow down the movement speed, allowing for faster recording and higher resolution. However, the resolution and droplet volume differ for each print mode, making it impossible to mix two or more different resolutions in a single print mode. This makes it impossible to improve gradation.

[0005] An object of the present invention is to provide a droplet ejection device that can achieve higher speeds, higher resolutions, and improved gradation, as well as a control method and program for the same. [Means for solving the problem]

[0006] The droplet ejection device of the present invention comprises a head having a nozzle, a flow path connected to the nozzle, and an actuator that applies pressure to the liquid in the flow path; a drive circuit that supplies a drive signal to the actuator; a movement mechanism that moves the head and the recording medium relatively along a movement direction; and a control unit, wherein the control unit is capable of executing a movement process that moves the head and the recording medium relatively using the movement mechanism, and an ejection process that supplies the drive signal from the drive circuit to the actuator to eject droplets from the nozzle, wherein the drive signals include a first drive signal that ejects droplets of a first volume, and a second drive signal that ejects droplets of a second volume different from the first volume, the second drive signal having a higher resolution in the movement direction than the first drive signal, and wherein the control unit selectively supplies the first drive signal and the second drive signal from the drive circuit to the actuator in the ejection process based on one recording command.

[0007] The control method of the present invention is a control method for a droplet ejection device comprising a head having a nozzle, a flow path connected to the nozzle, and an actuator that applies pressure to the liquid in the flow path, a drive circuit that supplies a drive signal to the actuator, and a movement mechanism that moves the head and a recording medium relatively along a movement direction, and is capable of executing a movement process in which the movement mechanism moves the head and the recording medium relatively, and an ejection process in which the drive circuit supplies the drive signal to the actuator to eject droplets from the nozzle, wherein the drive signals include a first drive signal that ejects droplets of a first volume, and a second drive signal that ejects droplets of a second volume different from the first volume, the second drive signal having a higher resolution in the movement direction than the first drive signal, and is characterized in that in the ejection process based on one recording command, the drive circuit selectively supplies the first drive signal and the second drive signal to the actuator.

[0008] The program of the present invention causes a control unit used in a droplet ejection device comprising a head having a nozzle, a flow path connected to the nozzle, and an actuator that applies pressure to the liquid in the flow path, a drive circuit that supplies a drive signal to the actuator, and a movement mechanism that moves the head and the recording medium relatively along a movement direction, to function as a means capable of executing a movement process in which the movement mechanism moves the head and the recording medium relatively, and an ejection process in which the drive circuit supplies the drive signal to the actuator to eject droplets from the nozzle, wherein the drive signals include a first drive signal that ejects droplets of a first volume, and a second drive signal that ejects droplets of a second volume different from the first volume, the second drive signal having a higher resolution in the movement direction than the first drive signal, and wherein the ejection process based on one recording command causes the drive circuit to selectively supply the first drive signal and the second drive signal to the actuator. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a plan view of a printer 10 according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view of a head 1 included in a printer 10. FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. 2 is a block diagram showing the electrical configuration of the printer 10. [Figure 5] 10 is a flowchart showing a program executed by a CPU 71 of the printer 10. FIG. [Figure 6] FIG. 10 is a schematic diagram for explaining a scanning process. [Figure 7] 1 is a schematic diagram showing a small droplet D1, a medium droplet D2, and a large droplet D3 of ink ejected from a nozzle. [Figure 8] 10 is a graph showing a first waveform signal X of the small droplet drive signal and a change in the position of the meniscus resulting from the supply of the signal. [Figure 9]10 is a graph showing a second waveform signal Y of the small droplet drive signal and a change in the position of the meniscus resulting from the supply of this signal. [Figure 10] 10 is a graph showing a third waveform signal Z of the small droplet drive signal and a change in the position of the meniscus resulting from the supply of this signal. DETAILED DESCRIPTION OF THE INVENTION

[0010] The printer 10 shown in FIG. 1 is one embodiment of a "droplet ejection device" according to the present invention. The printer 10 includes a head 1 having a plurality of nozzles 11 on its underside, a carriage 2 that holds the head 1, a scanning mechanism 3 that moves the carriage 2 in a scanning direction, a platen 4 that supports paper 9 from below, a transport mechanism 5 that transports paper 9 in a transport direction, and a control device 7. The paper 9 corresponds to the "recording medium" of the present invention. The scanning mechanism 3 corresponds to the "moving mechanism" of the present invention. The scanning direction, transport direction, and vertical direction are perpendicular to one another.

[0011] The nozzles 11 form four nozzle rows 11C, 11M, 11Y, and 11K. Each of the four nozzle rows 11C, 11M, 11Y, and 11K is composed of a plurality of nozzles 11 aligned in the transport direction and aligned in the scanning direction. The nozzles 11 forming nozzle row 11C eject cyan ink, the nozzles 11 forming nozzle row 11M eject magenta ink, the nozzles 11 forming nozzle row 11Y eject yellow ink, and the nozzles 11 forming nozzle row 11K eject black ink.

[0012] Any one of cyan, magenta, yellow, and black corresponds to the "first color" of the present invention, and a color different from the first color corresponds to the "second color" of the present invention. Of the four nozzle rows 11C, 11M, 11Y, and 11K, the nozzles 11 constituting one of the rows correspond to the "first nozzles" of the present invention, and the nozzles 11 constituting a row other than the row of the first nozzles correspond to the "second nozzles" of the present invention. Also, with regard to pressure chambers 12P (see FIG. 2) described below, the pressure chamber 12P communicating with the first nozzle corresponds to the "first flow path" of the present invention, and the pressure chamber 12P communicating with the second nozzle corresponds to the "second flow path" of the present invention.

[0013] The scanning mechanism 3 includes a pair of guides 31 and 32 that support the carriage 2, and a belt 33 connected to the carriage 2. The guides 31 and 32 and the belt 33 extend in the scanning direction. When the scanning motor 3M (see FIG. 4) is driven under the control of the control device 7, the belt 33 runs, and the carriage 2 and head 1 move in the scanning direction along the guides 31 and 32. As a result, the head 1 moves relative to the paper 9 on the platen 4 in the scanning direction.

[0014] The platen 4 is disposed below the carriage 2 and the head 1. A paper sheet P9 is supported on the upper surface of the platen 4.

[0015] The transport mechanism 5 includes an upstream roller 51 arranged upstream in the transport direction from the head 1, and a downstream roller 52 arranged downstream in the transport direction from the head 1. The head 1, carriage 2, and platen 4 are arranged between the upstream roller 51 and the downstream roller 52 in the transport direction.

[0016] Each of the upstream roller 51 and the downstream roller 52 is composed of a set of rotating members. The set of rotating members includes an upper rotating member arranged above the transport path of the paper 9 and a lower rotating member arranged below the transport path of the paper 9. The upper rotating member and the lower rotating member are arranged so that their peripheral surfaces are in contact with each other.

[0017] When the conveying motor 5M (see FIG. 4) is driven under the control of the control device 7, the rotating members of the upstream roller 51 and the downstream roller 52 rotate. As the rotating members of the upstream roller 51 and the downstream roller 52 rotate while clamping the paper 9, the paper 9 is conveyed in the conveying direction.

[0018] As shown in FIG. 2, the head 1 includes a flow path unit 12 and an actuator unit 13.

[0019] A plurality of nozzles 11 (see FIG. 1) open to the bottom surface of the flow path unit 12. A common flow path 12A and a plurality of individual flow paths 12B communicating with the common flow path 12A are formed inside the flow path unit 12. The common flow path 12A communicates with an ink tank (not shown). The individual flow paths 12B are individual flow paths for each nozzle 11, running from the outlet of the common flow path 12A through pressure chambers 12P to the nozzles 11. A plurality of pressure chambers 12P open to the top surface of the flow path unit 12. The pressure chambers 12P correspond to the "flow paths" of the present invention.

[0020] The actuator unit 13 includes three piezoelectric layers 13A, 13B, and 13C arranged on the upper surface of the flow channel unit 12 so as to cover the multiple pressure chambers 12P, a low potential electrode 13D arranged on the upper surface of the piezoelectric layer 13A, a high potential electrode 13E arranged on the upper surface of the piezoelectric layer 13B, and a drive electrode 13F arranged on the upper surface of the piezoelectric layer 13C. The low potential electrode 13D and the high potential electrode 13E are provided in common to the multiple pressure chambers 12P. The drive electrode 13F is provided for each pressure chamber 12P.

[0021] The low potential electrode 13D, the high potential electrode 13E, and the drive electrode 13F are electrically connected to a driver IC 14 (see FIG. 4). The driver IC 14 corresponds to the "drive circuit" of the present invention, and maintains the potential of the low potential electrode 13D at ground potential (0V) and the potential of the high potential electrode 13E at drive potential (VDD), while varying the potential of the drive electrode 13F between ground potential (0V) and drive potential (VDD). Specifically, the driver IC 14 generates a drive signal based on a control signal from the control device 7 and supplies the drive signal to the drive electrode 13F. This causes the potential of the drive electrode 13F to vary between the drive potential (VDD) and ground potential (0V).

[0022] 3, a portion of the piezoelectric layer 13C sandwiched between the driving electrode 13F and the high-potential electrode 13E in the vertical direction is referred to as a first active portion 13X1. A portion of the piezoelectric layers 13B and 13C sandwiched between the driving electrode 13F and the low-potential electrode 13D in the vertical direction is referred to as a second active portion 13X2. The first active portion 13X1 is mainly polarized upward, and the second active portion 13X2 is mainly polarized downward. The actuator unit 13 has an actuator 13X for each pressure chamber 12P, which is composed of one first active portion 13X1 and two second active portions 13X2.

[0023] 3(a), when the ground potential (0V) is applied to the driving electrode 13F, the potential difference between the driving electrode 13F and the high-potential electrode 13E generates an upward electric field in the first active portion 13X1 that is equal to the polarization direction of the first active portion 13X1, causing the first active portion 13X1 to contract in a direction perpendicular to the vertical direction. As a result, the stack of piezoelectric layers 13A, 13B, and 13C bends so as to convexly protrude toward the pressure chamber 12P.

[0024] When the potential of the drive electrode 13F is switched from ground potential (0V) to drive potential (VDD), the potential difference between the drive electrode 13F and the high-potential electrode 13E disappears, as shown in FIG. 3(b), and the contraction of the first active portion 13X1 is eliminated. Meanwhile, a potential difference between the drive electrode 13F and the low-potential electrode 13D is generated, generating a downward electric field in the second active portion 13X2 that is equal to its polarization direction, causing the second active portion 13X2 to contract in a direction perpendicular to the vertical direction. However, the second active portion 13X2 has the function of suppressing crosstalk and contributes little to the deformation of the laminate. Therefore, at this time, the laminate does not bend convexly in the direction away from the pressure chamber 12P, but remains flat. This increases the volume of the pressure chamber 12P compared to FIG. 3(a).

[0025] Subsequently, when the potential of the drive electrode 13F is switched from the drive potential (VDD) to the ground potential (0V), the potential difference between the drive electrode 13F and the low-potential electrode 13D disappears, and the contraction of the second active section 13X2 is eliminated, as shown in FIG. 3(a). Meanwhile, a potential difference is generated between the drive electrode 13F and the high-potential electrode 13E, which generates an upward electric field in the first active section 13X1 that is equal to the polarization direction of the first active section 13X1, causing the first active section 13X1 to contract in a direction perpendicular to the vertical direction. This causes the laminate to bend convexly toward the pressure chamber 12P. At this time, the volume of the pressure chamber 12P decreases, applying pressure to the ink in the pressure chamber 12P and causing an ink droplet to be ejected from the nozzle 11.

[0026] As described above, in this embodiment, the actuator 13X is driven by a "pull-fire method" in which the volume of the pressure chamber 12P is increased from a predetermined volume and then decreased to a volume equal to or less than the predetermined volume, thereby ejecting ink droplets from the nozzle 11.

[0027] As shown in Fig. 4, the control device 7 includes a CPU 71, a ROM 72, and a RAM 73. The ROM 72 stores programs and data for the CPU 71 to control various operations. The RAM 73 temporarily stores data used when the CPU 71 executes a program. The CPU 71 executes processing in accordance with the programs and data stored in the ROM 72 and RAM 73, based on data input from the PC 20. The CPU 71 corresponds to the "control unit" of the present invention.

[0028] Next, the program executed by the CPU 71 will be described with reference to FIG.

[0029] The CPU 71 first determines (S1) whether or not a recording command has been received from the PC 20. If it determines that a recording command has not been received (S1: NO), the CPU 71 repeats the process of S1.

[0030] If it is determined that a recording command has been received (S1: YES), the CPU 71 sets n=1 (S2).

[0031] After S2, the CPU 71 executes the nth (=1)th scanning process based on the recording command (S3). The scanning process includes a movement process in which the scanning mechanism 3 moves the head 1 in the scanning direction, and a discharge process in which the driver 14 supplies a drive signal to the actuator 13X to cause ink droplets to be discharged from the nozzles 11. In one scanning process, the head 1 discharges ink droplets onto a recording region R on the paper 9. The recording region R is a partial area of ​​the paper P, and is a rectangular area extending in the scanning direction that corresponds to one scanning process (see FIG. 6).

[0032] After S3, the CPU 71 executes a transport process to transport the paper 9 a predetermined distance in the transport direction (S4).

[0033] After S4, the CPU 71 sets n=n+1 (S5).

[0034] After S5, the CPU 71 executes the nth (=2 to Nth) scanning process based on the recording command (S6).

[0035] After S6, the CPU 71 determines whether n=N (S7).

[0036] If it is determined that n=N is not true (S7: NO), the CPU 71 returns the process to S4. Through this process, scanning is sequentially performed on each of the multiple recording areas R (see FIG. 6) aligned in the transport direction on the paper 9.

[0037] If it is determined that n=N (S7: YES), the CPU 71 executes a paper discharge process to transport the paper 9 to a paper discharge tray (not shown) of the printer 10 (S8), and ends the program.

[0038] Next, the drive signal supplied to the actuator 13X in the ejection process will be described with reference to FIGS.

[0039] 7, the drive signals include a small droplet drive signal that ejects small droplets D1, a medium droplet drive signal that ejects medium droplets D2, and a large droplet drive signal that ejects large droplets D3. The small droplets D1, medium droplets D2, and large droplets D3 are each ink droplets with different volumes. The volume of the small droplets D1 is smaller than the volume of the medium droplets D2, which is smaller than the volume of the large droplets D3. The drive signals also include a non-ejection drive signal that prevents the ejection of any ink droplets.

[0040] The medium droplets D2 and large droplets D3 are ejected one drop at a reference timing for each recording cycle T corresponding to the unit distance L, whereas the small droplets D1 are ejected one drop at a first timing before the reference timing for each recording cycle T (see the solid black dots), one drop at a second timing after the reference timing (see the hatched dots), or a total of two drops at both the first timing and the second timing (see the solid black dots and the hatched dots).

[0041] The small droplet drive signal includes a first waveform signal X (see Figure 8) that ejects a small droplet D1 at a first timing, a second waveform signal Y (see Figure 9) that ejects a small droplet D1 at a second timing, and a third waveform signal Z (see Figure 10) that ejects a small droplet D1 at both the first timing and the second timing.

[0042] The medium droplet D2 or the large droplet D3 corresponds to the "droplet of first volume" of the present invention, and the small droplet D1 corresponds to the "droplet of second volume" of the present invention. The drive signal for a medium droplet or the drive signal for a large droplet corresponds to the "first drive signal" of the present invention, and the drive signal for a small droplet corresponds to the "second drive signal" of the present invention.

[0043] In the ejection process based on one recording command, the CPU 71 causes the driver IC 14 to supply to the actuator 13X a drive signal selected from the drive signals based on the image data included in the recording command for each recording period T. The recording period T is the time required for the head 1 to move relative to the paper 9 by a unit distance L.

[0044] In addition, when the CPU 71 causes the driver IC 14 to supply a small droplet drive signal to the actuator 13X in an ejection process based on a recording command 1, it causes any one of the first waveform signal X, the second waveform signal Y, and the third waveform signal Z to be supplied as the small droplet drive signal.

[0045] By selectively using, as the small droplet drive signal, a first waveform signal X that ejects small droplets D1 at a first timing, a second waveform signal X that ejects small droplets D1 at a second timing, and a third waveform signal Z that ejects small droplets D1 at both the first and second timings, the resolution in the scanning direction of small droplets D1 can be doubled that of medium droplets D2 or large droplets D3. In other words, in this case, the resolution in the scanning direction of the small droplet drive signal is higher than that of the medium droplet drive signal or the large droplet drive signal. For example, in a head with a nozzle pitch in the scanning direction of 300 dpi, a resolution of 600 dpi can be achieved in the scanning direction for small droplets D1 alone.

[0046] 8 and 9, the first waveform signal X and the second waveform signal Y each include, within one recording period T, a main pulse wave Pm for ejecting an ink droplet, and a cancel pulse wave Pc that is applied after the main pulse wave Pm and that cancels the pressure wave in the pressure chamber 12P that is generated by the application of the main pulse wave Pm. The width Wc of the cancel pulse wave Pc is smaller than the width Wm of the main pulse wave Pm.

[0047] In the first waveform signal X and the second waveform signal Y, the width Wm of the main pulse wave Pm is the same, the width Wc of the cancel pulse wave Pc is the same, and the time Wx from the falling edge of the main pulse wave Pm to the rising edge of the cancel pulse wave Pc is also the same. That is, in the first waveform signal X and the second waveform signal Y, the width of at least one voltage change timing due to the pulse wave is the same.

[0048] 8, the first waveform signal X further includes an additional pulse wave Pn that is applied after the cancel pulse wave Pc. The width of the additional pulse wave Pn is smaller than the width Wc of the cancel pulse wave Pc. The additional pulse wave Pn amplifies the residual vibration in the pressure chamber 12P.

[0049] The main pulse wave Pm corresponds to the "first pulse wave" of the present invention, and the additional pulse wave Pn corresponds to the "second pulse wave" of the present invention.

[0050] As shown in FIG. 10, the third waveform signal Z includes, within one recording period T, two main pulse waves Pm, Pm' and two cancel pulse waves P that are applied after the main pulse waves Pm, Pm', respectively.

[0051] In the third waveform signal Z, the width Wm of the main pulse wave Pm associated with the ejection at the first timing and the width Wc of each cancel pulse wave Pc associated with the ejection at the first and second timings are the same as the widths Wm and Wc in the first waveform signal X and the second waveform signal Y, respectively. In the third waveform signal Z, the width Wm' of the main pulse wave Pm' associated with the ejection at the second timing is greater than the width Wm. The time Wx from the falling edge of the main pulse waves Pm and Pm' to the rising edge of the cancel pulse wave Pc is the same as the time Wx in the first waveform signal X and the second waveform signal Y.

[0052] The third waveform signal Z (see FIG. 10) is a combination of the first waveform signal X (see FIG. 8) and the second waveform signal Y (see FIG. 9), but at least some of the pulse waves constituting each signal are different. Specifically, the main pulse wave Pm' of the third waveform signal Z has a different width from the main pulse wave Pm of the second waveform signal Y. Furthermore, the third waveform signal Z does not include the additional pulse wave Pn that the first waveform signal X has.

[0053] In each of the waveform signals X, Y, and Z, at the start of the recording period T, the potential of the drive electrode 13F is ground potential (0V). At this time, the laminate of the piezoelectric layers 13A, 13B, and 13C is bent so as to convex toward the pressure chamber 12P (see FIG. 3(a)). When the potential of the drive electrode 13F is switched from ground potential (0V) to drive potential (VDD) at the rising edge of the main pulse wave Pm, the laminate becomes flat and the volume of the pressure chamber 12P increases (see FIG. 3(b)). At this time, ink is drawn from the common flow path 12A to the individual flow path 12B. Thereafter, when the potential of the drive electrode 13F is switched from drive potential (VDD) to ground potential (0V) at the falling edge of the main pulse wave Pm, the laminate is bent so as to convex toward the pressure chamber 12P (see FIG. 3(a)). As a result, the volume of the pressure chamber 12P decreases, increasing the ink pressure, and an ink droplet is ejected from the nozzle 11.

[0054] 8 to 10 show changes in the position of the meniscus formed in the nozzle 11 in accordance with changes in the potential of the drive electrode 13F. The vertical axis in each diagram indicates the position of the meniscus, with the positive side being the side facing upward from the nozzle 11 and the negative side being the side facing downward from the nozzle 11.

[0055] It can be seen from each diagram that as the main pulse waves Pm and Pm' are applied, the meniscus retreats toward the pressure chamber 12P, and as the main pulse waves Pm and Pm' subsequently fall, the meniscus protrudes downward from the nozzle 11 and flies as an ink droplet. Furthermore, as the cancel pulse wave Pc is applied, the meniscus retreats toward the pressure chamber 12P, causing the ink droplets that were flown in response to the application of the main pulse waves Pm and Pm' to separate from the meniscus.

[0056] After the cancel pulse wave Pc is applied, the meniscus moves gradually downward. In the first waveform signal X (see FIG. 8), after the cancel pulse wave Pc is applied, the additional pulse wave Pn is further applied, amplifying the residual vibration in the pressure chamber 12P, causing the meniscus to retreat again toward the pressure chamber 12P. After the additional pulse wave Pn is applied, the meniscus moves gradually downward. As a result, the positions of the meniscus at the end of the recording period T are substantially the same for the first waveform signal X, the second waveform signal Y, and the third waveform signal Z.

[0057] As described above, according to this embodiment, in the ejection process based on one print command, the CPU 71 selectively supplies a medium droplet drive signal, a large droplet drive signal, and a small droplet drive signal with a higher resolution than the medium droplet drive signal and the large droplet drive signal from the driver IC 14 to the actuator 13X (see FIG. 7). In this case, there is no need to slow down the movement speed of the carriage 2 to increase the resolution, so higher speeds can be achieved. Furthermore, by using the small droplet drive signal, higher resolution can be achieved. Furthermore, in the ejection process based on one print command, selectively using the low-resolution medium droplet drive signal and large droplet drive signal and the high-resolution small droplet drive signal can improve gradation.

[0058] The volume of an ink droplet (small droplet D1) corresponding to a high-resolution drive signal is smaller than the volume of an ink droplet (medium droplet D2 or large droplet D3) corresponding to a low-resolution drive signal. In this case, increasing the resolution of the small droplet D1 improves image quality.

[0059] Of the small droplet drive signals, the first waveform signal X (see FIG. 8) includes a main pulse wave Pm for ejecting ink droplets at a first timing, and an additional pulse wave Pn that amplifies the residual vibration in the pressure chamber 12P after the main pulse wave Pm. This ensures that the residual vibration in the pressure chamber 12P at the end of the recording period T is equivalent when ink droplets are ejected at the first timing using the first waveform signal X (see FIG. 8) and when ink droplets are ejected at the second timing using the second waveform signal Y (see FIG. 9). Therefore, regardless of whether the first waveform signal X or the second waveform signal Y is selected, the pressure in the pressure chamber 12P at the start of application of the next drive signal is equivalent, enabling continuous, stable ejection.

[0060] The width of at least one voltage change timing caused by the pulse wave is the same in the first waveform signal X and the second waveform signal Y (see FIGS. 8 and 9). This makes it possible to make the volume and flight speed of the ink droplets equivalent when the ink droplets are ejected at a first timing using the first waveform signal X (see FIG. 8) and when the ink droplets are ejected at a second timing using the second waveform signal Y (see FIG. 9).

[0061] The pulse wave of third waveform signal Z (see FIG. 10) is at least partially different from the pulse wave obtained by combining the pulse wave of first waveform signal X (see FIG. 8) and the pulse wave of second waveform signal Y (see FIG. 9). In this way, by not making the pulse wave of third waveform signal Z (see FIG. 10) a waveform obtained by simply combining the pulse wave of first waveform signal X (see FIG. 8) and the pulse wave of second waveform signal Y (see FIG. 9), the positions of the meniscus at the end of recording period T can be made substantially the same for first waveform signal X, second waveform signal Y, and third waveform signal Z. Consequently, continuous ejection can be stably performed.

[0062] The head 1 has nozzles 11 that eject ink droplets of four colors: cyan, magenta, yellow, and black (see FIG. 1). By using small droplet drive signals for each of these four colors, the gradation of each color is improved.

[0063] <Modification> Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design modifications are possible within the scope of the claims.

[0064] For example, in the above-described embodiment, the resolution of the small droplet drive signal is higher than the resolution of the medium droplet drive signal or the large droplet drive signal, but the resolution of the medium droplet drive signal or the large droplet drive signal may be higher than the resolution of the small droplet drive signal.

[0065] In the above-described embodiment, the head ejects liquids of multiple colors, but it may also be configured to eject liquid of only one color, for example, black ink.

[0066] The type of head is not limited to a serial type, and may be a line type. When the head is a line type, the transport mechanism 5 corresponds to the "moving mechanism" of the present invention, and may move the head and the recording medium relatively in the transport direction.

[0067] The droplet ejection device may include multiple heads.

[0068] The recording medium is not limited to paper, but may be, for example, cloth, a substrate, a plastic member, or the like.

[0069] In the above-described embodiment, the actuator has a three-layer structure including a drive electrode to which a high potential or a low potential is selectively applied, a high-potential electrode that is maintained at a high potential, and a low-potential electrode that is maintained at a low potential, but is not limited to this. For example, the actuator may have a two-layer structure including a drive electrode to which a high potential or a low potential is selectively applied, and a low-potential electrode that is maintained at a low potential.

[0070] The liquid ejected from the nozzles is not limited to ink, but may be any liquid (for example, a treatment liquid that aggregates or precipitates components in the ink, etc.).

[0071] The present invention is not limited to printers, but can also be applied to facsimiles, copiers, multifunction machines, etc. The present invention can also be applied to droplet ejection devices used for purposes other than image recording (for example, droplet ejection devices that eject conductive droplets onto a substrate to form a conductive pattern).

[0072] The program according to the present invention can be distributed by recording it on a removable recording medium such as a flexible disk or a fixed recording medium such as a hard disk, or can be distributed via a communication line. [Explanation of symbols]

[0073] 1 head 3. Scanning mechanism (moving mechanism) 71 CPU (control unit) 9. Paper (recording media) 10 Printer (droplet ejection device) 11 nozzles 12P pressure chamber (flow path) 13X Actuator 14 Driver IC (drive circuit) D1 droplets (droplets of second volume) D2 Medium Droplet (First Volume Droplet) D3 Large droplets (first volume droplets) Pm Main pulse wave (first pulse wave) Pn Additional pulse wave (second pulse wave) X First waveform signal (second drive signal) Y Second waveform signal (second drive signal) Z 3rd waveform signal (2nd drive signal)

Claims

1. a head having a nozzle, a flow path communicating with the nozzle, and an actuator that applies pressure to liquid in the flow path; a drive circuit for supplying a drive signal to the actuator; a movement mechanism that moves the head and the recording medium relatively in a movement direction; a control unit, the control unit is capable of executing a movement process of moving the head and the recording medium relatively by the movement mechanism, and a discharge process of supplying the drive signal from the drive circuit to the actuator to discharge droplets from the nozzle, the drive signals include a first drive signal that causes droplets of a first volume to be ejected, and a second drive signal that causes droplets of a second volume that is different from the first volume, the second drive signal having a higher resolution in the movement direction than the first drive signal; The droplet ejection device is characterized in that the control unit selectively supplies the first drive signal and the second drive signal from the drive circuit to the actuator in the ejection process based on one recording command.

2. The droplet ejection device according to claim 1 , wherein the second volume is smaller than the first volume.

3. the second drive signal includes a first waveform signal that causes droplets to be ejected at a first timing, and a second waveform signal that causes droplets to be ejected at a second timing that is later than the first timing; when the control unit controls the drive circuit to supply the second drive signal to the actuator in the ejection process based on one recording command, the control unit controls the drive circuit to supply one of the first waveform signal and the second waveform signal as the second drive signal; 2. The droplet ejection device according to claim 1, wherein the first waveform signal includes a first pulse wave for ejecting droplets at the first timing, and a second pulse wave for amplifying residual vibrations in the flow path after the first pulse wave.

4. the second drive signal includes a first waveform signal that causes droplets to be ejected at a first timing, and a second waveform signal that causes droplets to be ejected at a second timing that is later than the first timing; the control unit, when selectively supplying the second drive signal from the drive circuit to the actuator in the ejection process based on one recording command, supplies one of the first waveform signal and the second waveform signal as the second drive signal; the first waveform signal and the second waveform signal include one or more pulse waves; 2. The droplet ejection device according to claim 1, wherein the width of at least one voltage change timing caused by the pulse wave in the first waveform signal and the second waveform signal is the same.

5. the second drive signal includes a first waveform signal that causes droplets to be ejected at a first timing, a second waveform signal that causes droplets to be ejected at a second timing that is later than the first timing, and a third waveform signal that causes droplets to be ejected at both the first timing and the second timing; when the control unit selectively supplies the second drive signal from the drive circuit to the actuator in the ejection process based on one recording command, the control unit supplies any one of the first waveform signal, the second waveform signal, and the third waveform signal as the second drive signal; the control unit, when causing the drive circuit to supply the second drive signal to the actuator in the ejection process based on one recording command, causes any one of the first waveform signal, the second waveform signal, and the third waveform signal to be supplied as the second drive signal; The droplet ejection device according to claim 1 , wherein the pulse wave of the third waveform signal is at least partially different from the pulse wave obtained by combining the pulse wave of the first waveform signal and the pulse wave of the second waveform signal.

6. the flow paths include a first flow path through which a liquid of a first color flows and a second flow path through which a liquid of a second color different from the first color flows; 6. The droplet ejection device according to claim 1, wherein the nozzles include a first nozzle communicating with the first flow path and a second nozzle communicating with the second flow path.

7. A method for controlling a droplet ejection device comprising: a head having nozzles, flow paths communicating with the nozzles, and an actuator for applying pressure to liquid in the flow paths; a drive circuit for supplying a drive signal to the actuator; and a movement mechanism for relatively moving the head and a recording medium along a movement direction, the method comprising: a movement process in which the movement mechanism moves the head and the recording medium relative to each other, and a discharge process in which the drive circuit supplies the drive signal to the actuator to discharge droplets from the nozzle, the drive signals include a first drive signal that causes droplets of a first volume to be ejected, and a second drive signal that causes droplets of a second volume that is different from the first volume, the second drive signal having a higher resolution in the movement direction than the first drive signal; a control method for selectively supplying the first drive signal and the second drive signal from the drive circuit to the actuator in the ejection process based on one recording command.

8. a control unit used in a droplet ejection device, the control unit including a head having a nozzle, a flow path communicating with the nozzle, and an actuator for applying pressure to the liquid in the flow path, a drive circuit for supplying a drive signal to the actuator, and a movement mechanism for relatively moving the head and a recording medium along a movement direction; a program that functions as a means capable of executing a movement process in which the movement mechanism moves the head and the recording medium relatively, and a discharge process in which the drive circuit supplies the drive signal to the actuator to discharge droplets from the nozzle, the drive signals include a first drive signal that causes droplets of a first volume to be ejected, and a second drive signal that causes droplets of a second volume that is different from the first volume, the second drive signal having a higher resolution in the movement direction than the first drive signal; a recording command for selectively supplying the first drive signal and the second drive signal from the drive circuit to the actuator in the ejection process based on the recording command;

Images